Hsinchu, Taiwan

National Chiao Tung University , is a renowned public research university with international reputation located in Hsinchu City, Taiwan. NCTU was originally founded in Shanghai in 1896 and re-established in Taiwan by former Chiao Tung University faculty and alumni members in 1958, following the government of the Republic of China's forced relocation to Taiwan after the Chinese Civil War. The university's main campus is located close to the Hsinchu Science Park, Taiwan's national research center. The area is referred to as the Silicon Valley of Asia. More than 400 technology companies have been established in the park. The NCTU campus is also one of top tourist attractions in Hsinchu area. Wikipedia.

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National Chiao Tung University | Date: 2016-09-16

A system for detecting a core body temperature includes a detection unit, an ECG wave-filter, a body-temperature detection unit, a processing unit, a breath computing and processing unit, a heart-beat computing and processing unit, and a core body temperature computing and processing unit. The detection unit senses the body, and then the ECG wave-filter and body-temperature detection unit measures the electrical cardiac signal and the shell temperature, respectively. The processing unit collects the signals generated by the ECG wave-filter and body-temperature detection unit and transmits the collected signals to the breath computing and processing unit and the heart-beat computing and processing unit, which generate the core body temperature according to the received signals. Accordingly, it is possible to increase the physical parameters for monitoring the vital signs comprehensively. In addition, a method for detecting a core body temperature is also disclosed.

The present invention provides a system and method for blood pressure measurement, a computer program product using the method, and a computer-readable recording medium thereof. The present invention uses a sensor to measure an electrophysiological signal and establishes a personalized cardiovascular model through a numerical method, and re-establishes the personalized cardiovascular model through an optimization algorithm. Thus, a human physiological parameter generated from the re-established personal cardiovascular model matches the electrophysiological signal. Therefore, the present invention can provide accurate measurement results with the advantage of a small size, and can be applied to telemedicine field.

National Chiao Tung University | Date: 2016-09-16

A device of drowsiness detection and alarm includes a headrest, at least one brainwave sensor, a computing unit, a controlling unit and an accessory unit. The brainwave sensor is disposed on the headrest and configured to contact with a users head and detect a brainwave signal. The computing unit receives the brainwave signal from the brainwave sensor and calculates according to the brainwave signal to obtain a fatigue index. The controlling unit controls the accessory unit to activate according to the fatigue index. Therefore, when the user is drowsy and gradually loses consciousness, the accessory unit can immediately alarm the user and allow the user stay awake to avoid the occurrence of accidents. A method of drowsiness detection and alarm is also disclosed.

National Chiao Tung University | Date: 2015-11-06

The present invention provides a method for preparing a drug composition, which includes steps of dispersing an amphiphilic chitosan derivative, at least a hydrophobic drug, and at least a hydrophilic drug into a solvent to form a mixture solution, and the pH value of the mixture solution is adjusted to a range without precipitating the hydrophilic drug(s) and the hydrophobic drug(s), wherein the amphiphilic chitosan derivative is modified by a plurality of hydrophilic group(s) and a plurality of hydrophobic group(s); and after stirring the mixture solution for at least 12 hours, receiving the drug composition when the pH value of the mixture solution is between pH 6 to 7. The hydrophilic drug(s) and the hydrophobic drug(s) are encapsulated simultaneously by one-pot synthesis, and the protein could be modified by one-pot synthesis to provide a drug composition with multiple functions.

National Chiao Tung University | Date: 2016-07-12

A composite water purification apparatus and method thereof are provided. The composite water purification apparatus includes a container, a sacrificial anode, a photocatalyst anode and a cathode. The container is employed for receiving liquid including water and gas. The photocatalyst anode includes a photocatalyst for conducting a photocatalytic reaction. The cathode is electrolyzed with the sacrificial anode and the photocatalyst anode. The cathode, the sacrificial anode, and the photocatalyst anode are immersed in the container to contact the liquid. The present invention enhances the purity of the water, while prolonging the service life of the sacrificial anode.

National Chiao Tung University | Date: 2015-12-03

A photodetecting device and method of using the same are provided. The photodetecting device includes a transistor, a silicon nano-channel and a filter dye layer. The transistor includes a source, a drain and a gate. The silicon nano-channel connects the source and the drain, and is configured to receive light. The filter dye layer is over a light-receiving surface of the silicon nano-channel.

National Taiwan University, National Chiao Tung University and National Health Research Institute | Date: 2015-04-30

The invention utilizes virtual screening strategy to seek for current market drugs as anti-schizophrenia therapy drug repurposing. Drug repurposing strategy finds new uses other than the original medical indications of existing drugs. Finding new indications for such drugs will benefit patients who are in needs for a potential new therapy sooner since known drugs are usually with acceptable safety and pharmacokinetic profiles. In this study, repurposing marketed drugs for DAAO inhibitor as new schizophrenia therapy was performed with virtual screening on marketed drugs and its metabolites. The identified and available drugs and compounds were further confirmed with in vitro DAAO enzymatic inhibitory assay.

National Chiao Tung University | Date: 2016-02-04

An automatic probe construction system and the method thereof are provided. The automatic probe construction system includes a data dereference analysis module, a probe selection module, and a probe verification module. The data dereference analysis module dereferences a plurality of target data of an electronic apparatus according to a plurality of pointers, and constructs a plurality of candidate probes. The probe selection module constructs a control flow graph according to the candidate probes and an instruction code of an executable image file, to select via the control flow graph from the candidate probes at least one dedicated probe. The probe verification module searches the executable image file for an instruction code corresponding to the dedicated probe, to verify the dedicated probe. Therefore, the dedicated probe can be constructed automatically, and the number of the dedicated probes is thus limited.

National Chiao Tung University | Date: 2015-12-10

A dispersive element is incorporated with an optical sensor as a spectrometer. The dispersive element includes a guided-mode resonance filter having a plurality of resonance regions. The resonance regions respectively have different filter characteristics, each reflecting a first light beam of a tested light source or transmitting a second light beam of the tested light source light source to the optical sensor, wherein the wavelength of the first light beam is different from that of the second light beam. In one embodiment, the dispersive element is incorporated with an optical sensor to form a miniature, high-resolution and low-cost spectrometer. The spectrometer makes use of the transmission efficiencies of the resonance regions of the guided-mode resonance filter and the light intensity distribution detected by the photosensitive regions of the optical sensor to acquire the spectral data of the tested light source.

National Chiao Tung University | Date: 2016-01-19

A light-emitting device packaging structure is provided. The light-emitting device packaging structure includes a substrate, an array of light-emitting devices, an encapsulating layer, scattering particles, and a fluorescent material layer. The array of light-emitting devices is on the substrate. The encapsulating layer covers the array of light-emitting devices. The scattering particles are dispersed in the encapsulating layer. The fluorescent material layer is on the encapsulating layer.

National Chiao Tung University | Date: 2016-07-29

This disclosure proposed one kind of one-time programming and repeatably random read integrated circuit memory. The storage device of this memory programs the information by using dielectric-fuse mechanism. The main characteristics of dielectric fuse mechanisms is that by applying an electric field on the dielectrics, the ions or atoms in the dielectrics are drifted-out, or the dielectrics are burned-out, that create damage of the dielectric structure in a form of porosity, and the conductivity (resistivity) of tunneling current through the dielectrics changes the state from high conductivity (resistivity) to low conductivity (resistivity). The dielectric fuse mechanism has been integrated in VLSI circuits, completed the validation, and implemented by the fabrication of CMOS process.

National Chiao Tung University and Himax Technologies | Date: 2016-11-03

A silicon-controlled rectifier (SCR) includes a first-type field, a second-type first field and a second-type second field disconnectedly formed in a first-type well; an entire first-type doped region formed within the first-type field; a segmented second-type doped region formed within the second-type first field; and a segmented first-type doped region formed within the second-type second field.

National Chiao Tung University | Date: 2016-01-06

A heat conducting module includes a main body. The main body includes a first surface and a second surface. The first surface is thermally connected to a heat absorbing body. The second surface is opposite to the first surface and is fluidly connected to a channel. The second surface has a plurality of grooves disposed along a direction. The channel allows a fluid to flow a long the direction. Each of the grooves includes a first sub-groove and at least one second sub-groove. The first sub-groove at least has a third surface close to the first surface. The first sub-groove at least partially communicates with the second sub-groove, and the second sub-groove is at least partially fluidly connected with the third surface.

National Chiao Tung University | Date: 2017-02-01

The present invention provides a method for preparing a drug composition, which includes steps of dispersing an amphiphilic chitosan derivative, at least a hydrophobic drug, and at least a hydrophilic drug into a solvent to form a mixture solution, and the pH value of the mixture solution is adjusted to a range without precipitating the hydrophilic drug(s) and the hydrophobic drug(s), wherein the amphiphilic chitosan derivative is modified by a plurality of hydrophilic group(s) and a plurality of hydrophobic group(s); and after stirring the mixture solution for at least 12 hours, receiving the drug composition when the pH value of the mixture solution is between pH 6 to 7. The hydrophilic drug(s) and the hydrophobic drug(s) are encapsulated simultaneously by one-pot synthesis, and the protein could be modified by one-pot synthesis to provide a drug composition with multiple functions.

Liu C.-H.,National Chiao Tung University
2016 IEEE Global Communications Conference, GLOBECOM 2016 - Proceedings | Year: 2016

This paper studies the energy efficiency of a dense heterogeneous cellular network (HetNet) consisting of K independent Poisson point processes (PPPs) of base stations (BSs) and what the maximum limit on the energy efficiency can be achieved by cell association. The cell load statistics is first derived for power-law cell association functions and it can characterize the accurate void cell probability of a BS in each tier of the HetNet. A green cell association (GCA) scheme is proposed based on the downlink spectrum efficiency per unit power consumption of a BS and its GCA function is derived in a very simple and feasible form. The energy efficiency of a BS is defined as the mean downlink spectrum efficiency per unit power consumption and its tight lower bounds and limits for the GCA, maximum received power association (MRPA) and nearest base station association (NBA) schemes are all found. We show that the energy efficiency achieved by the GCA scheme is the maximum energy efficiency limit that is not surmounted by other non-green cell association schemes such as MRPA and NBA and the cell loads between different tiers are also balanced by the GCA scheme very well. © 2016 IEEE.

Amer M.,National Chiao Tung University | Wang C.-C.,National Chiao Tung University
Renewable and Sustainable Energy Reviews | Year: 2017

This study reviewed the defrosting techniques applicable for the heating, ventilation, air-conditioning, and refrigeration industry, including passive, active, and system techniques. The passive methods normally use treated surfaces by changing the surface morphology through micro-grooved, anti-frost coating, hydrophilic, hydrophilic, or superhydropholic coating. For passive defrosting techniques, the microgrooved surfaces can improve the drainage of the frost melt effectively. It is generally agreed that the superhydropholic coating can delay the initialization of frosting and provides less water adhesion during defrosting. Yet defrosting performance for hydrophobic surfaces outperforms hydrophilic and uncoated surfaces. Active and system techniques, including electrohydrodynamic (EHD), low-frequency oscillation, and ultrasonic vibration methods, hot gas reverse cycle, electric heater, desiccant dehumidifiers and controlling strategies are reviewed. The EHD defrosting method is proved to be comparatively effective in natural or laminar flow operation. Test results also indicate that utilization of alternative current source is superior to the direct current source. The electrode with negative polarity is better than positive polarity as far as frost accumulation is concerned. The low-frequency oscillation is ineffective in defrosting while ultrasonic vibration provides effective frost removal and can delay the frost growth appreciably. Test results indicate that the ultrasonic oscillation poses considerable positive influence on defrosting either operated continuously or intermittently, in direct contact or not. For system defrosting, the hot gas reverse cycle is comparatively expensive to install but the efficiency, COP, and energy consumption are superior to the other system methods. Desiccants, either solid or liquid, can be employed in association with the system defrosting methods to lower energy consumption. There were various controlling strategies to detect the frost formation and to decide the best time to initiate defrosting. However, many of them were applicable to some specific systems and environments and require further investigations to test the relevant reliability, stability, and repeatability. © 2017 Elsevier Ltd

OBJECTIVE:: To evaluate the risk of subsequent primary ovarian insufficiency (POI) amongst patients with a history of polycystic ovarian syndrome (PCOS). METHODS:: This nationwide, population-based study is an inspection and review of data from the 1998 to 2012 Taiwan National Health Insurance Research Database. In a sample of 1,000,000 randomly sampled individuals, women with PCOS (exposure group; n?=?7,049) and women without PCOS (contrast group; n?=?70,490) were compared. Women initially diagnosed with PCOS at less than 15 or more than 35 years of age were excluded. Each woman with PCOS was age-matched to 10 women without PCOS. The diagnoses of PCOS and POI (coded using International Classification of Diseases, 9th Revision, Clinical Modification) were further confirmed with blood test results and ultrasonographic findings to ensure the accuracy of the diagnoses. RESULTS:: POI occurred more among women with PCOS compared with women without PCOS (3.73% vs 0.44%; P?

Lin Y.-P.,National Chiao Tung University
IEEE Transactions on Signal Processing | Year: 2017

Hybrid precoding that combines analog RF processing and digital baseband processing has been shown to be a promising technique for transceivers with limited number of RF chains. The RF processing, due to power and complexity issue, is typically done by using phase shifters. A recent study shows that hybrid precoding is no loss of generality if each coefficient of the analog precoder is implemented by using two phase shifters. In this paper, we consider two possible implementation structures that use Two pHase shIfters for each Coefficient (THIC). These two structures, having the same performance when the phases can take on continuum values, behave differently upon quantization, as the analysis shows. For a small number of quantization bits, the precoder implemented using THIC is a good approximation of the unquantized one. With 3-bit phase shifters, the performance is close to that of the unquantized system in multiuser communications, where the performance is more sensitive to quantization errors. While the analysis in this paper is done assuming high-resolution quantization, simulations show that the result is accurate even for coarse quantization. © 2017 IEEE.

Lo C.-W.,National Chiao Tung University | Sahoo V.,National Chiao Tung University | Lu M.-C.,National Chiao Tung University
ACS Nano | Year: 2017

Ice formation is a catastrophic problem affecting our daily life in a number of ways. At present, deicing methods are costly, inefficient, and environmentally unfriendly. Recently, the use of superhydrophobic surfaces has been suggested as a potential passive anti-icing method. However, no surface is able to repel frost formation at a very cold temperature. In this work, we demonstrated the abilities of spatial control of ice formation and confinement of the ice-stacking direction. The control and confinement were achieved by manipulating the local free energy barrier for frosting. The V-shaped microgroove patterned surface, which possessed these abilities, exhibited the best anti-icing and deicing performances among the studied surfaces. The insight of this study can be applied to alleviate the impact of icing on our daily life and in many industrial systems. © 2017 American Chemical Society.

Shen Y.-A.,National Chiao Tung University | Chen C.,National Chiao Tung University
Scripta Materialia | Year: 2017

The effects of Sn orientation and grain boundary misorientation on formation of Cu-Sn intermetallic compounds (IMCs) during electromigration were investigated. Significant anisotropic diffusion of Cu in Sn grains was observed. Interfacial Cu-Sn IMCs may grow rapidly, dissolve, or remain intact, depending on the angle of c-axis of Sn grains with the electron flow. In addition, grain boundaries did not play an important role in Cu diffusion because they are mostly cyclic twins. © 2016 Acta Materialia Inc.

Su J.-J.,National Chiao Tung University | Macdonald A.H.,University of Texas at Austin
Physical Review B - Condensed Matter and Materials Physics | Year: 2017

We present a theory of spatially indirect exciton condensate states in systems composed of a pair of electrically isolated Bernal graphene bilayers. The ground-state phase diagram in a two-dimensional displacement-field/inter-bilayer-bias space includes layer-polarized semiconductors, spin-density-wave states, exciton condensates, and states with mixed excitonic and spin order. We find that two different condensate states, distinguished by a chirality index, are stable under different electrical control conditions. © 2017 American Physical Society.

Hou W.-Y.,National Chiao Tung University | Wu Y.-K.,National Chiao Tung University
Organic Letters | Year: 2017

Described is a method for the formal γ-arylation of cyclohexenones allowing synthesis of a remote all-carbon quaternary center. The process involves the palladium-catalyzed α-arylation of a α-substituted cyclic vinylogous ester followed by the Stork-Danheiser transposition. The synthetic utility of this protocol is featured in the total syntheses of (±)-12-hydroxy-13-methylpodocarpa-8,11,13-trien-3-one, (±)-3β,12-dihydroxy-13-methylpodocarpane-8,11,13-triene, and (±)-O-methyl nimbinone. © 2017 American Chemical Society.

Lu H.-F.F.,National Chiao Tung University
Proceedings of 2016 International Symposium on Information Theory and Its Applications, ISITA 2016 | Year: 2016

A two-phase, rate-split, static nonorthogonal decode- and-forward protocol for the cooperative relay network consisting of a source, multiple half-duplex relays and a destination, all having single antenna, is proposed in this paper. In the proposed protocol, the desired transmission rate R is split into rates R1 and R2; then the source sends rate R1 during the first phase and rate R2 during the second. Explicit expressions for R1 and R2 are also given. It is shown that the proposed protocol achieves the optimal cooperative diversity derived from the information theoretic cut-set bound in high SNR regime. Compared to the compress- and-forward protocol, the proposed protocol is much simpler for practical implementation, holds the same for any number of relays and requires only local channel-state-information at each node, except for a small feedback of rate R1 as well as a selection index of relays. © 2016 IEICE.

Wang H.,National Chiao Tung University
Frontiers in Bioscience - Landmark | Year: 2016

Treatments for anti-N-methyl-D-aspartate (NMDA) receptor encephalitis include immunotherapy with steroids, intravenous immunoglobulin, plasma exchange, or plasmapheresis as first-line treatments, immunotherapy with rituximab or cyclophosphamide as second-line treatments, and tumor removal. In this systematic review, we evaluated previous studies and examined the association between certain microRNAs and anti-NMDA receptor encephalitis to investigate the performance of different treatment combinations. The efficacies of different combinations of treatments classified into the following four categories were compared: (I) intravenous immunoglobulin administration, (II) plasmapheresis or plasma exchange, (III) treatment with rituximab or cyclophosphamide and (IV) tumor removal. Statistical analyses showed that treatment combinations including at least two of these categories resulted in higher efficacy rates than treatment with a single form of therapy. These findings suggest that if a patient is not recovering, converting to other therapies is more likely to result in early recovery than continuing on the original therapy.

Huang A.B.,National Chiao Tung University
Proceedings of the 5th International Conference on Geotechnical and Geophysical Site Characterisation, ISC 2016 | Year: 2016

The term silt/sand or M/S is proposed as an inclusive abbreviation of soils that can span from sand with very little silt, silty sand to pure silt. It is generally believed that sands with fines (particles passing #200 sieve) tend to be more compressible. Because of their low permeability, cone penetration tests (CPT) in sands with fines can be partially drained. High compressibility makes the soil more contractive and thus showing lower resistance in undrained shearing. Significant ground subsidence can also be associated with the high compressibility of M/S/ soils. For CPT in granular soils with similar density and stress states, the high compressibility and partial drainage can both contribute to lower cone tip resistance. Natural granular soils are likely to contain fines than being clean (fines content < 5%). Studies on M/S soils are far less than those on clean sands. Because of the unique geological setting, the author had the opportunity to work with a local M/S deposit in Central Western Taiwan in the past 25 years. Procedures for laboratory soil element tests as well as CPT calibration tests using reconstituted specimens have been developed and a series of tests performed. Practical undisturbed sampling techniques in M/S soils were experimented and applied. Methods to correlate cyclic strength, fines contents and cone tip resistance in M/S deposit were proposed. The concepts of equivalent granular void ratio and state parameter were experimented in compiling the test data. The paper describes the new characterization techniques developed and lessons learned in the interpretation of test data for the studied M/S soils. © 2016 Australian Geomechanics Society.

Hang H.-M.,National Chiao Tung University
2016 Asia-Pacific Signal and Information Processing Association Annual Summit and Conference, APSIPA 2016 | Year: 2016

To achieve the goal of frontal vehicle detection in night-driving condition, we propose an effective method to detect the red taillights of vehicles. The challenge is that the taillight images captured with automatic exposure typically are overexposed, which makes red color segmentation often erroneous. Instead of customizing the camera hardware to tackle this problem, we combine morphological and logical operations to extract the overexposed region in taillights, which leads to a much more reliable taillight detection scheme. Then, we develop a robust pairing process that clusters two taillight candidates into a pair that represents a vehicle. Several criteria are considered in the pairing process, including the similarities of area, shape, and height of a pair of lights. In addition, we include the temporal consistency criterion; that is, a pair of taillights should be continually detected for a certain duration of time. An energy function is used to aggregate these criteria together. Our experiments show that both the missing and false detection rates are lower than 1.5%. © 2016 Asia Pacific Signal and Information Processing Association.

Hang H.-M.,National Chiao Tung University
2016 Asia-Pacific Signal and Information Processing Association Annual Summit and Conference, APSIPA 2016 | Year: 2016

To meet a wide range of needs for video applications such as remote desktop, video conference, distance education, and cloud gaming, the ISO/ITU Joint Collaborative Team on Video Coding (JCT-VC) committee is recently specifying the Screen Content Coding (SCC) standard, as one of the extensions of High Efficiency Video Coding (HEVC). In this paper, the hash search method of the standard adopted Intra Block Copy (IBC) coding tool for SCC is investigated. We collect the coded data using the current hash table and examine their efficiency and explore possible ways for further improvement. A low complexity scheme of selecting effective hash nodes and a modified hash key generation method are presented. Experimental results show that the proposed method reduces on the average 37% or at most 70% hash table memory usage but it preserves the similar BD-rate savings and encoding complexity when integrated into the SCM-3.0 test model. © 2016 Asia Pacific Signal and Information Processing Association.

Chen T.,National Chiao Tung University
International Journal of Intelligent Systems | Year: 2017

Ubiquitous hotel recommendation is a highly popular type of location-aware service. However, existing recommendation systems have several problems. This paper proposes a fuzzy-weighted-average (FWA) and backpropagation-network (BPN) approach for overcoming the hindrances of ubiquitous hotel recommendation and improving its effectiveness, whereby FWA is applied to evaluate the overall performance of a hotel. A BPN was constructed to defuzzify the overall performance. In addition, the personally preferred index is proposed for addressing the traveler choices of a dominated hotel. The effectiveness of the proposed methodology was tested using a field study in a small region in Seatwen, Taichung City, Taiwan. © 2016 Wiley Periodicals, Inc.

Shieh G.,National Chiao Tung University
Multivariate Behavioral Research | Year: 2016

Analysis of covariance (ANCOVA) is commonly used in behavioral and educational research to reduce the error variance and improve the power of analysis of variance by adjusting the covariate effects. For planning and evaluating randomized ANCOVA designs, a simple sample-size formula has been proposed to account for the variance deflation factor in the comparison of two treatment groups. The objective of this article is to highlight an overlooked and potential problem of the exiting approximation and to provide an alternative and exact solution of power and sample size assessments for testing treatment contrasts. Numerical investigations are conducted to reveal the relative performance of the two procedures as a reliable technique to accommodate the covariate features that make ANCOVA design particularly distinctive. The described approach has important advantages over the current method in general applicability, methodological justification, and overall accuracy. To enhance the practical usefulness, computer algorithms are presented to implement the recommended power calculations and sample-size determinations. © 2016 Taylor & Francis Group, LLC

« Proterra delivers 100th electric bus | Main | Lucid Air debuts in New York; completes first high speed stability test at 217 mph » Researchers at KAUST have developed and used a novel way of increasing the chemical reactivity of a two-dimensional molybdenum disulfide material to produce a cheap and effective catalyst for water splitting to produce hydrogen. This technique may also have potential benefits for other manufacturing industries. One route to hydrogen generation is by electrolysis: passing an electrical current through water via two electrodes to cause a chemical reaction that breaks the water molecule into its component hydrogen and oxygen atoms. The speed of this hydrogen evolution reaction can be increased using a catalyst on the electrodes. Platinum is a perfect material for the job, but is it very expensive. Two-dimensional layered transition metal dichalcogenide (TMD) materials such as Molybdenum disulfide (MoS ) have been recognized as one of the low-cost and efficient electrocatalysts for hydrogen evolution reaction (HER). The crystal edges that account for a small percentage of the surface area, rather than the basal planes, of MoS monolayer have been confirmed as their active catalytic sites. As a result, extensive efforts have been developing in activating the basal planes of MoS for enhancing their HER activity. Here, we report a simple and efficient approach—using a remote hydrogen-plasma process—to creating S-vacancies on the basal plane of monolayer crystalline MoS ; this process can generate high density of S-vacancies while mainly maintaining the morphology and structure of MoS monolayer. The density of S-vacancies (defects) on MoS monolayers resulted from the remote hydrogen-plasma process can be tuned and play a critical role in HER, as evidenced in the results of our spectroscopic and electrical measurements. Molybdenum disulfide is a two-dimensional material very similar to graphene. Previous experimental and theoretical results have verified its excellent catalytic potential and indicated that the hydrogen evolution reaction takes place at its jagged edges, while its flat surface planes remain chemically inert. Lain-Jong Li, Professor of Material Science and Engineering at KAUST, with colleagues from the National Chiao Tung University (Taiwan) and the National Applied Research Laboratories in Taiwan created their molybdenum disulfide using a process called chemical vapor deposition. A sample was then transferred to a graphite substrate and placed in a vacuum chamber in which the researchers created a hydrogen plasma. This process removed some of the sulfur atoms from the surface of the sample. By adjusting the sample’s time in the plasma, the team could control the density of these sulfur vacancies. The researchers confirmed the changes in catalytic activity and also found a useful offshoot of this process. Controlling the atomic composition of molybdenum disulfide could also lead to the development of electrical, optical and magnetic devices.

News Article | April 17, 2017
Site: news.mit.edu

A single cell can contain a wealth of information about the health of an individual. Now, a new method developed at MIT and National Chiao Tung University could make it possible to capture and analyze individual cells from a small sample of blood, potentially leading to very low-cost diagnostic systems that could be used almost anywhere. The new system, based on specially treated sheets of graphene oxide, could ultimately lead to a variety of simple devices that could be produced for as little as $5 apiece and perform a variety of sensitive diagnostic tests even in places far from typical medical facilities. The material used in this research is an oxidized version of the two-dimensional form of pure carbon known as graphene, which has been the subject of widespread research for over a decade because of its unique mechanical and electrical characteristics. The key to the new process is heating the graphene oxide at relatively mild temperatures. This low-temperature annealing, as it is known, makes it possible to bond particular compounds to the material’s surface. These compounds in turn select and bond with specific molecules of interest, including DNA and proteins, or even whole cells. Once captured, those molecules or cells can then be subjected to a variety of tests. The findings are reported in the journal ACS Nano, in a paper co-authored by Neelkanth Bardhan, an MIT postdoc, and Priyank Kumar PhD ’15, now a postdoc at ETH Zurich; Angela Belcher, the James Mason Crafts Professor in biological engineering and materials science and engineering at MIT and a member of the Koch Institute for Integrative Cancer Research; Jeffrey Grossman, the Morton and Claire Goulder and Family Professor in Environmental Systems at MIT; Hidde L. Ploegh, a professor of biology and member of the Whitehead Institute for Biomedical Research; Guan-Yu Chen, an assistant professor in biomedical engineering at National Chiao Tung University in Taiwan; and Zeyang Li, a doctoral student at the Whitehead Institute. Other researchers have been trying to develop diagnostic systems using a graphene oxide substrate to capture specific cells or molecules, but these approaches used just the raw, untreated material. Despite a decade of research, other attempts to improve such devices’ efficiency have relied on external modifications, such as surface patterning through lithographic fabrication techniques, or adding microfluidic channels, which add to the cost and complexity. The new finding offers a mass-producible, low-cost approach to achieving such improvements in efficiency. The heating process changes the material’s surface properties, causing oxygen atoms to cluster together, leaving spaces of bare graphene between them. This makes it relatively easy to attach other chemicals to the surface, which can interact with specific molecules of interest. The new research demonstrates how that basic process could potentially enable a suite of low-cost diagnostic systems, for example for cancer screening or treatment follow-up. For this proof-of-concept test, the team used molecules that can quickly and efficiently capture specific immune cells that are markers for certain cancers. They were able to demonstrate that their treated graphene oxide surfaces were almost twice as effective at capturing such cells from whole blood, compared to devices fabricated using ordinary, untreated graphene oxide, says Bardhan, the paper’s lead author. The system has other advantages as well, Bardhan says. It allows for rapid capture and assessment of cells or biomolecules under ambient conditions within about 10 minutes and without the need for refrigeration of samples or incubators for precise temperature control. And the whole system is compatible with existing large-scale manufacturing methods, making it possible to produce diagnostic devices for less than $5 apiece, the team estimates. Such devices could be used in point-of-care testing or resource-constrained settings. Existing methods for treating graphene oxide to allow functionalization of the surface require high temperature treatments or the use of harsh chemicals, but the new system, which the group has patented, requires no chemical pretreatment and an annealing temperature of just 50 to 80 degrees Celsius (122 to 176 F). While the team’s basic processing method could make possible a wide variety of applications, including solar cells and light-emitting devices, for this work the researchers focused on improving the efficiency of capturing cells and biomolecules that can then be subjected to a suite of tests. They did this by enzymatically coating the treated graphene oxide surface with peptides called nanobodies — subunits of antibodies, which can be cheaply and easily produced in large quantities in bioreactors and are highly selective for particular biomolecules. The researchers found that increasing the annealing time steadily increased the efficiency of cell capture: After nine days of annealing, the efficiency of capturing cells from whole blood went from 54 percent, for untreated graphene oxide, to 92 percent for the treated material. The team then performed molecular dynamics simulations to understand the fundamental changes in the reactivity of the graphene oxide base material. The simulation results, which the team also verified experimentally, suggested that upon annealing, the relative fraction of one type of oxygen (carbonyl) increases at the expense of the other types of oxygen functional groups (epoxy and hydroxyl) as a result of the oxygen clustering. This change makes the material more reactive, which explains the higher density of cell capture agents and increased efficiency of cell capture. “Efficiency is especially important if you’re trying to detect a rare event,” Belcher says. “The goal of this was to show a high efficiency of capture.” The next step after this basic proof of concept, she says, is to try to make a working detector for a specific disease model. In principle, Bardhan says, many different tests could be incorporated on a single device, all of which could be placed on a small glass slide like those used for microscopy. “I think the most interesting aspect of this work is the claimed clustering of oxygen species on graphene sheets and its enhanced performance in surface functionalization and cell capture,” says Younan Xia, a professor of chemistry and biochemistry at Georgia Institute of Technology who was not involved in this work. “It is an interesting idea.” The work was supported by the Army Research Office Institute for Collaborative Biotechnologies and MIT’s Tata Center and Solar Frontiers Center.

Shellaiah M.,National Chiao Tung University | Rajan Y.C.,National Chiao Tung University | Lin H.-C.,National Chiao Tung University
Journal of Materials Chemistry | Year: 2012

Two novel highly soluble triarylamine dendrimers TPAD1 and TPAD2 with N 4,N 6-dibutyl-1,3,5-triazine-4,6-diamine probe were synthesized via normal synthetic routes. Both dendrimers (TPAD1 and TPAD2) form H-bonded donor-acceptor-donor (D-A-D) supramolecular triads TPAD1-PBI-TPAD1 and TPAD2-PBI-TPAD2 with 3,4,9,10-perylene tetra carboxylic diimide derivative (PBI). The presence of multiple H-bonds in the solution state was elucidated by 1H NMR titrations and IR spectral studies. J-aggregations and electron/energy transfers provided by both dendrimers were verified by UV-Vis and photoluminescence (PL) titrations with PBI and the particle sizes of supramolecular triads were calculated by X-ray diffraction (XRD) analysis. Similarly, both dendrimers also showed sensitivities towards Cu 2+ in comparison with 19 interfering metal ions, which were evidenced via UV-Vis and PL titraions in both single and dual metal systems. The maximum detection limit of Cu 2+ ions was determined to be 20 ppm from PL titrations for both dendrimers, and the 1:2 stoichiometry of the complexes formed by both dendrimers (TPAD1-Cu 2+ and TPAD2-Cu 2+) were calculated by Job plots based on UV-Vis absorption titrations. More importantly, the binding mechanism of the 1,3,5-triazine-4,6-diamine probe of both dendrimers was well characterized by 1H and 13C NMR titrations ([D 8]THF:D 2O = 2:1 in vol.) and supported by the fluorescence reversibility by adding metal ions and PMDTA sequentially. © 2012 The Royal Society of Chemistry.

Lin H.-C.,National Chiao Tung University | Lin Y.-H.,National Chiao Tung University
Applied Physics Letters | Year: 2010

We demonstrated a fast response and large tunable focusing imaging system consisting of a lens module and a liquid crystal (LC) lens based on the switching of two modes of a LC lens: the negative LC lens and positive LC lens. By discarding the conventional operation of a positive LC lens only in the imaging system, large tunable focusing range can be achieve from 300 to 10 cm owning to the phase change between the positive and the negative LC lens; meanwhile, the response time is fast (∼433ms). The potential applications are autofocused cell phones, and cameras. © 2010 American Institute of Physics.

Teo T.-A.,National Chiao Tung University
Photogrammetric Engineering and Remote Sensing | Year: 2011

This paper presents three bias-compensated models for the geometric correction of high-resolution satellite images. The proposed models include the bias-compensated rigorous sensor model (RSM) in the orbital space, the bias-compensated RSM in the image space, and the bias-compensated rational function model (RFM) in the image space. The RSM and RFM use the on-board data and sensor-oriented rational polynomial coefficients (RPCs) provided in imagery metadata, respectively. Test images include QuickBird, WorldView-1, and WorldView-2 Basic images. Experimental results indicate that the bias-compensated RSM using the zero order polynomials function in the orbital space provides higher accuracy. A comparison of the bias-compensated RSM and RFM in the image space shows that these models behave similarly, and the maximum difference in root-mean-square error is less than 0.1 m. These results show that all the proposed methods obtain accuracy of better than 1 pixel, except for the translation in the image space. © 2011 American Society for Photogrammetry and Remote Sensing.

Huang H.-T.,National Chiao Tung University | Tsai C.-C.,National Chiao Tung University | Huang Y.-P.,National Chiao Tung University
Optics Express | Year: 2010

This work presents a novel "pulsed spray (PS)" process for the coating of yellow YAG:Ce3+ phosphor on blue InGaN-based light emitting diodes (LEDs). To coat a phosphor layer of high quality on an LED chip surface, the PS approach is used and studied because of the uniform color distribution, providing a wide range of color temperatures. This PS coating approach applies phosphor by exploiting mechanical principles without risk of chemical pollution. Additionally, it can be applied to wire-bonded LEDs and an array of LED chips on a substrate to fabricate a large-area, planar illumination system of high optical quality, which is easy to manufacture. © 2010 Optical Society of America.

Wu J.-S.,National Chiao Tung University | Cheng S.-W.,National Chiao Tung University | Cheng Y.-J.,National Chiao Tung University | Hsu C.-S.,National Chiao Tung University
Chemical Society Reviews | Year: 2015

Harvesting solar energy from sunlight to generate electricity is considered as one of the most important technologies to address the future sustainability of humans. Polymer solar cells (PSCs) have attracted tremendous interest and attention over the past two decades due to their potential advantage to be fabricated onto large area and light-weight flexible substrates by solution processing at a lower cost. PSCs based on the concept of bulk heterojunction (BHJ) configuration where an active layer comprises a composite of a p-type (donor) and an n-type (acceptor) material represents the most useful strategy to maximize the internal donor-acceptor interfacial area allowing for efficient charge separation. Fullerene derivatives such as [6,6]-phenyl-C61or71-butyric acid methyl ester (PCBM) are the ideal n-type materials ubiquitously used for BHJ solar cells. The major effort to develop photoactive materials is numerously focused on the p-type conjugated polymers which are generally synthesized by polymerization of electron-rich donor and electron-deficient acceptor monomers. Compared to the development of electron-deficient comonomers (acceptor segments), the development of electron-rich donor materials is considerably flourishing. Forced planarization by covalently fastening adjacent aromatic and heteroaromatic subunits leads to the formation of ladder-type conjugated structures which are capable of elongating effective conjugation, reducing the optical bandgap, promoting intermolecular π-π interactions and enhancing intrinsic charge mobility. In this review, we will summarize the recent progress on the development of various well-defined new ladder-type conjugated materials. These materials serve as the superb donor monomers to prepare a range of donor-acceptor semi-ladder copolymers with sufficient solution-processability for solar cell applications. This journal is © The Royal Society of Chemistry.

Kuo T.-W.,National Chiao Tung University | Liu W.-R.,Industrial Technology Research Institute of Taiwan | Chen T.-M.,National Chiao Tung University
Optics Express | Year: 2010

A red phosphor CaZnOS:Eu2+ was synthesized by solid state reaction and has been evaluated as a candidate for white LEDs. For this material, the XRD, PL, PL excitation (PLE) and diffuse reflection spectra have also been investigated. CaZnOS:Eu2+ reveals a broad absorption band and good color purity. By utilizing a mixture of red-emitting CaZnOS:Eu 2+, green-emitting (Ba,Sr)2SiO4:Eu2+ and yellow-emitting Y3Al5O12:Ce3+ as light converters, an intense white InGaN-based blue-LED (∼460 nm) was fabricated to exhibit a high color-rendering index Ra of 85 at a correlated color temperature of 4870 K. Based on the results, we are currently evaluating the potential application of CaZnOS:Eu2+ as a red-emitting bluechip convertible phosphor. © 2010 Optical Society of America.

Wei C.C.,National Chi Nan University | Chen J.,National Chiao Tung University
Optics Express | Year: 2010

While coherency between an RF-tone and OFDM signals in RoF systems at 60 GHz is de-correlated by fiber dispersion, both phase rotation term (PRT) on each subcarrier and inter-carrier interference (ICI) between subcarriers are induced at a receiver. We analytically calculate the powers of PRT and ICI under different parameters, such as subcarrier number, modulation format, laser linewidth and transmission distance. Moreover, dispersion-induced ICI is shown to be non-Gaussian distributed by its kurtosis, and its distribution depends on system parameters. Therefore, using only the power of ICI cannot predict accurate bit error rate (BER) and corresponding power penalty. We propose to use t-distribution to fit the distribution of ICI, and it can be used to compute BER precisely. © 2010 Optical Society of America.

Hung C.-H.,National Chiao Tung University | Tien C.-H.,National Chiao Tung University
Optics Express | Year: 2010

For the phosphor-converted light-emitting diodes (pcLEDs), the interaction of the illuminating energy with the phosphor would not just behave as a simple wavelength-converting phenomenon, but also a function of various combinations of illumination and viewing geometries. This paper presents a methodology to characterize the converting and scattering mechanisms of the phosphor layer in the pcLEDs by the measured bidirectional scattering distribution functions (BSDFs). A commercially available pcLED with conformal phosphor coating was used to examine the validity of the proposed model. The close agreement with the measurement illustrates that the proposed characterization opens new perspectives for phosphor-based conversion and scattering feature for white lighting uses. © 2010 Optical Society of America.

Huang C.-H.,National Chiao Tung University | Chen T.-M.,National Chiao Tung University
Optics Express | Year: 2010

We have synthesized a series of single-composition emissiontunable Ca 9La(PO4)7:Eu2+,Mn2+ (CLP:Eu 2+,Mn2+) phosphors by solid state reactions. Through an effective resonance-type energy transfer, the CLP:Eu2+,Mn 2+ phosphors exhibit a systematically varied hues from green, yellow, and eventually to red and the relative intensity of green and red emissions can be tuned by adjusting the concentration OfMn2+, respectively. The energy transfer from Eu2+ to Mn2+ in CLP:Eu2+,.Mn 2+ has been studied and demonstrated to be a resonant type via a dipole-quadrupole mechanism based on the decay lifetime data and the energy transfer critical distance was estimated to be 11.36 Å by using the spectral overlap methods. A warm white light emitting diode (WLED) with CIE chromaticity coordinates of (0.35, 0.31), superior color-rendering index (Ra) of 91.5 and lower correlated color temperature (CCT) of 4,496 K was fabricated by combining a 365 nm UV-InGaN chip and a phosphor blend of yellow-emitting (Ca0.98Eu0.005Mn0.015)9La(PO 4)7 and blue-emitting BaMgAl10O 17:Eu2+. © 2010 Optical Society of America.

Kuo T.-W.,National Chiao Tung University | Liu W.-R.,Industrial Technology Research Institute of Taiwan | Chen T.-M.,National Chiao Tung University
Optics Express | Year: 2010

A series of alkaline earth borophosphate phosphors, (Ba,Sr) 3BP3O12 doped with Eu2+ ions, were synthesized by a solid state reaction. Two emission bands at 465 nm and 520 nm were attributed to the f-d transitions of doped Eu2+ ions occupying in two different cation sites in host lattices and emission color variation was observed by substituting the M2+ sites, which was rationalized in terms of two competing factors of the crystal field strength and bond covalence. Green and bluish-white pc-LEDs were fabricated by combination of a 370 nm near-UV chip and composition-optimized Ba3BP3O 12:Eu2+ and (Ba,Sr)3BP3O 12:Eu2+ phosphors, respectively. The series of phosphors may serve as a promising green and bluish-white luminescent materials used in fabrication of near UV-based white pc-LEDs. © 2010 Optical Society of America.

Yu J.-C.,National Chiao Tung University | Yu P.,National Chiao Tung University
Optics Express | Year: 2010

For advanced CMOS processes, inverse lithography promises better patterning fidelity than conventional mask correction techniques due to a more complete exploration of the solution space. However, the success of inverse lithography relies highly on customized cost functions whose design and know-how have rarely been discussed. In this paper, we investigate the impacts of various objective functions and their superposition for inverse lithography patterning using a generic gradient descent approach. We investigate the most commonly used objective functions, which are the resist and aerial images, and also present a derivation for the aerial image contrast. We then discuss the resulting pattern fidelity and final mask characteristics for simple layouts with a single isolated contact and two nested contacts. We show that a cost function composed of a dominant resist-image component and a minor aerial-image or image-contrast component can achieve a good mask correction and contour targets when using inverse lithography patterning. © 2010 Optical Society of America.

Su H.-C.,National Chiao Tung University | Hsu J.-H.,National Chiao Tung University
Dalton Transactions | Year: 2015

Recently, solid-state light-emitting electrochemical cells (LECs) based on ionic transition metal complexes (iTMCs) have attracted much research interest since they have the advantages of a simple device structure, a low operation voltage and compatibility with air-stable electrodes. These properties enable LECs to be cost-effective, versatile and power-efficient organic light-emitting sources. However, it is generally not easy to modify the molecular structure to achieve balanced carrier mobilities without altering the photoluminescence quantum yield of the iTMC. Furthermore, the carrier balance and the consequent device efficiency of single-layered LECs would not be easy to optimize since no carrier injection and transport layers can be used. In this perspective, some reported techniques to improve carrier balance of LECs based on iTMCs are described and reviewed. The importance and impact of these studies are highlighted. The effects on device lifetime and turn-on time because of employing these techniques to improve the carrier balance are also discussed. This perspective concludes that even with electrochemically doped layers, improving the carrier balance of LECs would be required for realizing efficient electroluminescent emission from simple-structure organic light-emitting sources. © 2015 The Royal Society of Chemistry.

Liu Z.-H.,National Tsing Hua University | Chen J.-C.,National Chiao Tung University
IEEE Transactions on Mobile Computing | Year: 2012

The WiMAX Forum has defined a two-tiered mobility management to minimize handover delay and packet loss. However, it leads to another problem: When to perform ASN GW relocation? The standards only define the ASN GW relocation procedures without specifying when the ASN GW relocation should be performed. It is left for vendors and operators to develop their own proprietary solutions. In this paper, we propose an algorithm, which incorporates traditional Admission Control (AC) and Wiener Process (WP)-based prediction algorithms to determine when to carry out ASN GW relocation. We further develop an analytical model to analyze the proposed algorithm. Simulations are also conducted to evaluate the performance of the proposed algorithm. The results show that the proposed algorithm can improve the performance significantly in terms of blocking probability, dropping probability, average serving rate, and average signaling overhead. © 2006 IEEE.

Lin P.-H.,National Chiao Tung University | Tsai S.-H.,National Chiao Tung University
IEEE Transactions on Vehicular Technology | Year: 2012

This paper investigates transmit antenna selection for linearly precoded multiuser multiple-input-multiple-output (MU-MIMO) systems. First, in some precoded single-user MIMO systems, using all transmit antennas does not always lead to the best performance due to ill-conditioned channel matrices. This condition motivates us to investigate whether a similar result can be obtained in MU-MIMO systems. Based on the derived analytical results, we found that, for a given number of transmit antennas, decreasing the number of active transmit antennas [number of radio frequency (RF) units] always degrades system performance in the linearly precoded MU-MIMO systems. However, in practical systems, RF units are expensive. To reduce the hardware cost, antenna selection is usually used to reduce the number of RF units. Thus, we further analyze the performance loss due to transmit antenna selection (TAS). These analytical results provide good design references for using TAS in practical systems. Moreover, based on the analytical results, we proposed several simple TAS algorithms for linearly precoded MU-MIMO systems. Complexity analysis and simulation results show that the computational complexity of the proposed algorithms can significantly be reduced, whereas the performance is still comparable with the optimal selection scheme. As a result, the analyzed results enable us to better understand how TAS affects the MU-MIMO systems. In addition, the proposed algorithms make TAS more feasible to be used in practical systems. © 2012 IEEE.

Chung Y.-H.,National Chiao Tung University | Chang C.-J.,National Chiao Tung University
IEEE Transactions on Vehicular Technology | Year: 2012

This paper proposes a new balanced resource scheduling (BRS) scheme with adaptive priority thresholds for orthogonal frequency-division multiple-access (OFDMA) downlink systems. The BRS scheme achieves an excellent balance between quality-of-service (QoS) requirement guarantee and system throughput enhancement, whereas conventional schemes cannot explicitly and accurately control this tradeoff. Based on the adaptive priority threshold of each user, the BRS scheme first performs a priority-based resource allocation (RA) algorithm for users whose priority value is larger than its priority threshold to fulfill the QoS requirement. The BRS scheme then performs a channel-state-information (CSI)-based RA algorithm for the remaining users to enhance system throughput. To achieve balance between QoS guarantee and throughput enhancement, a fuzzy inference priority threshold generator adaptively and intelligently adjusts the priority threshold of each user. Simulation results show that the proposed BRS scheme with adaptive priority threshold enhances the system throughput by 16%, 8.5%, 8.2%, and 46.8% at traffic load of 0.93, compared with conventional adaptive radio RA (RRA), utility-based RRA, utility-based throughput maximization and complexity reduction scheduling, and fairness and QoS guarantee scheduling with fuzzy controls schemes, respectively, under a QoS requirement guarantee. This approach also outperforms the BRS scheme with fixed priority thresholds in both throughput enhancement and QoS guarantee. © 2006 IEEE.

Pao H.-T.,National Chiao Tung University | Fu H.-C.,Huaqiao University
Energy Policy | Year: 2013

This study investigates the causal relationship between clean and non-clean energy consumption and economic growth in Brazil over the period of 1980-2009. Clean energy consumption at aggregated level of total renewable energy consumption and disaggregated levels of hydroelectric, new renewables, and nuclear energy consumption are tested within a production function framework. A cointegration test reveals a long-term equilibrium relationship between real output, capital, labor, and renewable and non-renewable energy consumption at aggregated level, and a long-term equilibrium relationship between real output, capital, labor, and hydroelectric/new renewables/nuclear and fossil fuel energy consumption at disaggregated level. The capital, labor, and new renewables elasticities of real output are positive and statistically significant, other energy consumption item's elasticities are insignificant. The results from error correction model reveal the interdependencies between new renewables, nuclear, fossil fuel, and total non-renewable energy consumption and economic growth, the unidirectional causality from hydroelectric/total renewable consumption to economic growth, the substitutability between new renewables and fossil fuel consumption, and the substitutability between new renewables and nuclear energy consumption. Additionally, nuclear and new renewables energy consumption responds to bring the system back to equilibrium. Overall, aggregated analysis may obscure the relationship between different types of clean energy consumption and economic growth. © 2013 Elsevier Ltd.

Chiu C.-H.,National Tsing Hua University | Chiu C.-H.,National Chiao Tung University | Jost L.,EcoMinga Foundation | Chao A.,National Tsing Hua University
Ecological Monographs | Year: 2014

Until now, decomposition of abundance-sensitive gamma (regional) phylogenetic diversity measures into alpha and beta (within- and between-group) components has been based on an additive partitioning of phylogenetic generalized entropies, especially Rao's quadratic entropy. This additive approach led to a phylogenetic measure of differentiation between assemblages: (gamma alpha)/gamma. We show both empirically and theoretically that this approach inherits all of the problems recently identified in the additive partitioning of non-phylogenetic generalized entropies. When within-assemblage (alpha) quadratic entropy is high, the additive beta and the differentiation measure (gammaalpha)/gamma always tend to zero (implying no differentiation) regardless of phylogenetic structures and differences in species abundances across assemblages. Likewise, the differentiation measure based on the phylogenetic generalization of Shannon entropy always approaches zero whenever gamma phylogenetic entropy is high. Such critical flaws, inherited from their non-phylogenetic parent measures (Gini-Simpson index and Shannon entropy respectively), have caused interpretational problems. These flaws arise because phylogenetic generalized entropies do not obey the replication principle, which ensures that the diversity measures are linear with respect to species addition or group pooling. Furthermore, their complete partitioning into independent components is not additive (except for phylogenetic entropy). Just as in the non-phylogenetic case, these interpretational problems are resolved by using phylogenetic Hill numbers that obey the replication principle. Here we show how to partition the phylogenetic gamma diversity based on Hill numbers into independent alpha and beta components, which turn out to be multiplicative. The resulting phylogenetic beta diversity (ratio of gamma to alpha) measures the effective number of completely phylogenetically distinct assemblages. This beta component measures pure differentiation among assemblages and thus can be used to construct several classes of similarity or differentiation measures normalized onto the range [0, 1]. We also propose a normalization to fix the traditional additive phylogenetic similarity and differentiation measures, and we show that this yields the same similarity and differentiation measures we derived from multiplicative phylogenetic diversity partitioning. We thus can achieve a consensus on phylogenetic similarity and differentiation measures, including N-assemblage phylogenetic generalizations of the classic Jaccard, Sørensen, Horn, and Morisita-Horn measures. Hypothetical and real examples are used for illustration. © 2014 by the Ecological Society of America.

Lin T.-Y.,National Chiao Tung University
Molecular BioSystems | Year: 2010

Thiol-disulfide exchange reactions between thiol-disulfide oxidoreductases (e.g. thioredoxin or Trx) and client proteins can obtain a rate several orders faster than those between chemical reagents (e.g. dithiothreitol) and client proteins. The active sites of these oxidoreductases are characterized by a CXXC motif. The XX dipeptide of Trx is GP. By altering the C-terminal X to A, K and D, it is shown that the P → K mutation confers the largest effect on the redox potential, which it elevated by 28 mV, while the P → D mutation displays the smallest variation. The change in pK a of the nucleophilic thiol also follows this trend. However, GK and GA react faster with thioredoxin reductase, exhibiting a rate rank of GK > GA > GP > GD, while the rates toward insulin and PDI follow the order GP > GA > GK > GD. The rate change spans two to three orders of magnitude. This work demonstrates that redox reactivity does not correlate simply with pK a and redox potential, but instead supports the important role of interaction between proteins in determining the fast reactivity and rate order of Trx. A reaction mechanism involving the transient formation of a Trx-protein binding complex is proposed for the oxidoreduction of protein thiols-disulfides. Furthermore, studies on insulin reduction show that Trx acts as an enzyme rather than a redox couple. These results provide explanations for the observed variations of the CXXC motif in PDI-like proteins as well as the conservation of the CXXC motif in Trx. © The Royal Society of Chemistry 2010.

Chen W.-C.,National Chiao Tung University | Johnson A.L.,Texas A&M University
Computers and Operations Research | Year: 2010

Data envelopment analysis (DEA) uses extreme observations to identify superior performance, making it vulnerable to outliers. This paper develops a unified model to identify both efficient and inefficient outliers in DEA. Finding both types is important since many post analyses, after measuring efficiency, depend on the entire distribution of efficiency estimates. Thus, outliers that are distinguished by poor performance can significantly alter the results. Besides allowing the identification of outliers, the method described is consistent with a relaxed set of DEA axioms. Several examples demonstrate the need for identifying both efficient and inefficient outliers and the effectiveness of the proposed method. Applications of the model reveal that observations with low efficiency estimates are not necessarily outliers. In addition, a strategy to accelerate the computation is proposed that can apply to influential observation detection. © 2009 Elsevier Ltd.

Hsu C.-H.,National Chiao Tung University | Fan Y.-S.,National Chiao Tung University | Liu P.-T.,National Chiao Tung University
Applied Physics Letters | Year: 2013

Multi-level storage capability of resistive random access memory (RRAM) using amorphous indium-gallium-zinc-oxide (InGaZnO) thin film is demonstrated by the TiN/Ti/InGaZnO/Pt device structure under different operation modes. The distinct four-level resistance states can be obtained by varying either the trigger voltage pulse or the compliance current. In addition, the RRAM devices exhibit superior characteristics of programming/erasing endurance and data retention for the application of multi-level nonvolatile memory technology. Physical transport mechanisms for the multi-level resistive switching characteristics are also deduced in this study. © 2013 American Institute of Physics.

Chen W.-Y.,National Chiao Tung University | Chen Y.-C.,National Chiao Tung University
Analytical and Bioanalytical Chemistry | Year: 2010

Saliva contains various proteins, particularly abundant are phosphoproteins, that may be related to disease occurrences and that play significant roles in a biological system. Thus, medical diagnostics will benefit tremendously if disease-related protein biomarkers are discovered from saliva. In this paper, we propose and demonstrate an approach using functional zinc oxide coated iron oxide magnetic nanoparticles (Fe3O4@ZnO MNPs) as affinity probes to selectively enrich phosphoproteins from complex saliva samples and as microwave absorbers to assist the enrichment and subsequent tryptic digestion of trapped proteins under microwave heating. The target species trapped by MNPs were characterized by matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) combined with protein database search. Entire analysis time was shortened to less than 20 min. The detection limit of this approach for a monophosphopeptide was as low as 250 pM (10 μL). © 2010 Springer-Verlag.

Yang S.-H.,National Chiao Tung University | Chen Y.-P.,National Chiao Tung University
Neurocomputing | Year: 2012

We propose a method for designing artificial neural networks (ANNs) for prediction problems based on an evolutionary constructive and pruning algorithm (ECPA). The proposed ECPA begins with a set of ANNs with the simplest possible structure, one hidden neuron connected to an input node, and employs crossover and mutation operators to increase the complexity of an ANN population. Additionally, cluster-based pruning (CBP) and age-based survival selection (ABSS) are proposed as two new operators for ANN pruning. The CBP operator retains significant neurons and prunes insignificant neurons on a probability basis and therefore prevents the exponential growth of an ANN. The ABSS operator can delete old ANNs with potentially complex structures and then introduce new ANNs with simple structures; thus, the ANNs are less likely to be trapped in a fully connected topology. The ECPA framework incorporates constructive and pruning approaches in an attempt to efficiently evolve compact ANNs. As a demonstration of the method, ECPA is applied to three prediction problems: the Mackey-Glass time series, the number of sunspots, and traffic flow. The numerical results show that ECPA makes the design of ANNs more feasible and practical for real-world applications. © 2012.

Lu C.-H.,National Chiao Tung University | Chang F.-C.,National Chiao Tung University
ACS Catalysis | Year: 2011

Palladium nanoparticles (Pd NPs) capped with a certain protective group possessing stable reactivity of Pd-catalyzed reactions has been quickly and easily synthesized. The thiol-Pd2+ complexes of C12- Pd2+ and POSS-Pd2+ are prepared by the ligand exchange of acetate groups on Pd(OAc)2 with 1-dodecanthiol and SH-POSS (polyhedral oligomeric silsesquioxane), respectively. After thermal treatment at 120 °C for 30 min, the C12-Pd2+ and POSS-Pd 2+ turn into C12-Pd(0) and POSS-Pd(0) NPs through the reduction of palladium cations with thiol groups. Unlike the well-known metallic Pd NPs with constituent Pd atoms arranged in an orderly repeating pattern, the cores of these thial-Pd(0) NPs are composed of a disordered (amorphous) aggregation of Pd atoms due to the steric hindrance caused by the affinity between in situ Pd atoms and thial groups. The relatively larger gaps between two adjacent POSS moieties, formed by solvent permeation when one isobutyl group approaches another, can be employed as transportation channels for reactants such as iodobenzene (IB). Thus, methyl trans-cinnamate is produced as soon as the reactants of IB and methyl acrylate are added in the POSS-Pd(0) NP-catalyzed Heck coupling. In contrast, an activation time of ∼1 h is needed for C 12-Pd(0) NPs to replace these long-alkyl protective groups with iodobenzene. © 2011 American Chemical Society.

Chiou Y.-D.,National Chiao Tung University | Hsu Y.-J.,National Chiao Tung University
Applied Catalysis B: Environmental | Year: 2011

We demonstrated for the first time that single-crystalline Se nanorods (NRs), prepared with a facile chemical reduction approach at room temperature, may display noticeable catalytic activities toward methylene blue degradation in dark environment after subjected to a short period of irradiation. Such capability of photocatalysis in the dark for Se NRs was attributed to the memory effect related to pre-irradiation treatment. The result of spin-trapping electron paramagnetic resonance measurement suggests that a sustained supply of OH radicals could be attained for Se NRs upon the cease of irradiation, which is accountable for the memory photocatalytic effect as revealed in the dark. As compared to the commercial P-25 TiO 2 powder and Se nanoparticles, the as-synthesized Se NRs exhibited superior photocatalytic performance under UV illumination, demonstrating their potential as active photocatalysts in relevant redox reactions. Furthermore, the recycling test reveals that Se NRs could be promisingly utilized in the long-term course of photocatalysis. The present Se NRs may find potential use for unique photocatalytic applications, in which typical photocatalysis prevails under light illumination, while memory photocatalytic effect takes over when irradiation is interrupted. © 2011 Elsevier B.V.

Chang S.-M.,National Chiao Tung University | Liu W.-S.,National Chiao Tung University
Applied Catalysis B: Environmental | Year: 2011

In this study, we examined the effects of surface and bulk doping on the photocatalytic activity of vanadium (V)-doped TiO2 on the basis of charge trapping, separation, and interfacial transfer. Moreover, we characterized the microstructures and electronic structures of the two types of doped TiO2 and the chemical states of the doped V ions to elucidate the causes of the different physicochemical properties. The photocatalytic activity of the doped TiO2 was enhanced by 1.9 times when the V ions were doped only in the surface lattice at a surface V/Ti molar ratio of 3.0×10-1, in contrast, bulk doping caused detrimental effects. Reduced species, including V3+ and V4+ ions, were formed in the interstitial anatase lattice. These impurities introduced occupied and unoccupied energy levels, which were close to and in the conduction band of TiO2, respectively. The V3+/V4+ ions within the TiO2 lattice inhibited charge diffusion to the surface through deep trapping. In contrast, the impurities present only in the surface lattice increased the number of surface trapped holes and facilitated the interfacial charge transfer from the photoactivated TiO2 to adsorbates. Heavy doping at the surface resulted in the formation of V2O5. The p-n junction between the TiO2 and V2O5 separated charge carriers and additionally promoted the photocatalytic activity of the surface-doped TiO2. © 2010 Elsevier B.V.

Wu P.-C.,National Chiao Tung University | Lee W.,National Chiao Tung University
Applied Physics Letters | Year: 2013

We report on the phase behavior and dielectric properties of the liquid crystal (LC) 4′-n-octyloxy-4-cyanobiphenyl dispersed with graphene nanoplatelets (GNPs). The temperature-dependent dielectric permittivity at 104 Hz and its derivative with respect to the temperature reveal that the incorporation of GNPs in a LC cell leads to the modification of crystalline polymorphism and shift in phase transition temperature owing to the enhanced positional and orientational order. Additionally, the dielectric data between 1 and 103 Hz show that the dopant reduces the ionic concentration and alters the diffusivity in the LC mesophases. © 2013 AIP Publishing LLC.

Tsui B.-Y.,National Chiao Tung University | Kao M.-H.,National Chiao Tung University
Applied Physics Letters | Year: 2013

Although high channel electron mobility has been reported after some passivation techniques, the performance of n-channel Ge metal-oxide- semiconductor field-effect transistor is still limited by the high Schottky barrier height at the metal/n-Ge contact interface, which comes from the Fermi level pinning effect. Recent experiments demonstrated that the Schottky barrier height can be reduced by inserting a thin dielectric layer between metal and Ge. However, the mechanism has not been well clarified. In this paper, the metal induced gap state model, the dipole layer model, and the fixed charge model are verified by varying contact metals, dielectric thicknesses, as well as the annealing temperatures. The pinning factor is improved slightly by dielectric insertion but its value is independent of the dielectric thickness and is still much lower than the ideal value of the non-pinning case. This pinning effect is consistent with the Fermi level pinning at the metal/TiO2 interface. After thermal process, no interfacial layer forms at the TiO2/Ge interface and the TiO2 crystallizes gradually after annealing but the Schottky barrier height increases. Since the amount of fixed charges in the thin dielectric layer estimated from a metal-insulator-semiconductor structure is about 2 × 1011 cm-2 and is insufficient to produce the observed 0.5 eV Schottky barrier height reduction, it is thus recommended that the main mechanism comes from the change of interface dipoles and the annealing effect is attributed to the short-range ordering of the TiO2 layer. Furthermore, dielectric with low conduction band offset which has good thermal stability should be explored. © 2013 AIP Publishing LLC.

Hu S.-H.,University of Washington | Hu S.-H.,National Chiao Tung University | Gao X.,University of Washington
Journal of the American Chemical Society | Year: 2010

Compact nanostructures with highly integrated functionalities are of considerable current interest to drug delivery, multimodality imaging, and electronic devices. A key challenge, however, is how to combine individual components together without interfering or sacrificing their original electronic and optical properties. Here, we demonstrate a new class of nanocomposites with spatially separated functionalities. We further demonstrate magnetic field modulated imaging and an innovative application of this technology in cancer cell treatment, magnetolytic therapy, based on magnetically controlled mechanical damage to cell membranes.

Martin L.W.,University of Illinois at Urbana - Champaign | Chu Y.-H.,National Chiao Tung University | Ramesh R.,University of California at Berkeley | Ramesh R.,Lawrence Berkeley National Laboratory
Materials Science and Engineering R: Reports | Year: 2010

The growth and characterization of functional oxide thin films that are ferroelectric, magnetic, or both at the same time are reviewed. The evolution of synthesis techniques and how advances in in situ characterization have enabled significant acceleration in improvements to these materials are described. Methods for enhancing the properties of functional materials or creating entirely new functionality at interfaces are covered, including strain engineering and layering control at the atomic-layer level. Emerging applications of these functional oxides such as achieving electrical control of ferromagnetism and the future of these complex functional oxides is discussed. © 2010 Elsevier B.V. All rights reserved.

A class of thermal stable of green-emitting phosphors Ba(3)Y(PO(4))(3):Ce(3+),Tb(3+) (BYP:Ce(3+),Tb(3+)) and red-emitting phosphors Ca(3)Y(AlO)(3)(BO(3))(4):Eu(3+) (CYAB:Eu(3+)) for white-light fluorescent lamps were synthesized by high temperature solid-state reaction. We observed a decay of only 3% at 150 °C for BYP:0.25Ce3+,0.25Tb3+ (3% for LaPO4:Ce(3+),Tb(3+)), and a decay of 4% for CYAB:0.5Eu(3+) (7% for Y(2)O(3):Eu(3+), 24% for Y(2)O(2)S:Eu(3+)). The emission intensity of composition-optimized Ba(3)(Y(0.5)Ce(0.25)Tb(0.25))(PO(4))(3) is 70% of that of commercial LaPO(4):Ce(3+),Tb(3+) phosphors, and the CIE chromaticity coordinates are found to be (0.323, 0.534). The emission intensity of Ca(3)(Y(0.5)Eu(0.5))(AlO)(3)(BO(3))(4) is 70% and 83% of those of Y(2)O(3):Eu(3+) and Y(2)O(2)S:Eu(3+) phosphors, respectively, and the CIE chromaticity coordinates are redder (0.652, 0.342) than those of Y(2)O(3):Eu(3+) (0.645, 0.347) and Y(2)O(2)S:Eu(3+) (0.647, 0.343). A white-light fluorescent lamp is fabricated using composition-optimized Ba(3)(Y(0.5)Ce(0.25)Tb(0.25))(PO(4))(3) and Ca(3)(Y(0.5)Eu(0.5))(AlO)(3)(BO(3))(4) phosphors and matching blue-emitting phosphors. The results indicate that the quality of the brightness and color reproduction is suitable for application in shortwave UV fluorescent lamps. The white-light fluorescent lamp displays CIE chromaticity coordinates of x = 0.33, y = 0.35, a warm white light with a correlated color temperature of 5646 K, and a color-rendering index of Ra = 70.

Li Y.-M.,National Chiao Tung University
Decision Support Systems | Year: 2010

The paper considers the pricing and allocation issues of distributing digital contents via Web and P2P channels. Utilizing a game theoretic model, the allocation equilibrium with respect to various business goals is examined. We find that the P2P channel is always under-utilized in an organization, and present an incentive scheme to achieve an efficient channel configuration. Under a market structure with sequential moves, both channels set higher price and collect higher profit. Particularly, the second mover enjoys higher price and market share. A provider with integrated channels will charge a higher price on the Web channel and the Web channel becomes under-utilized. © 2010 Elsevier B.V. All rights reserved.

Pao H.-T.,National Chiao Tung University | Tsai C.-M.,National Chiao Tung University
Energy Policy | Year: 2010

This paper examines dynamic causal relationships between pollutant emissions, energy consumption and output for a panel of BRIC countries over the period 1971-2005, except for Russia (1990-2005). In long-run equilibrium energy consumption has a positive and statistically significant impact on emissions, while real output exhibits the inverted U-shape pattern associated with the Environmental Kuznets Curve (EKC) hypothesis with the threshold income of 5.393 (in logarithms). In the short term, changes in emissions are driven mostly by the error correction term and short term energy consumption shocks, as opposed to short term output shocks for each country. Short-term deviations from the long term equilibrium take from 0.770 years (Russia) to 5.848 years (Brazil) to correct. The panel causality results indicate there are energy consumption-emissions bidirectional strong causality and energy consumption-output bidirectional long-run causality, along with unidirectional both strong and short-run causalities from emissions and energy consumption, respectively, to output. Overall, in order to reduce emissions and not to adversely affect economic growth, increasing both energy supply investment and energy efficiency, and stepping up energy conservation policies to reduce unnecessary wastage of energy can be initiated for energy-dependent BRIC countries. © 2010 Elsevier Ltd.

Ou-Yang M.,National Chiao Tung University | Jeng W.-D.,National Chiao Tung University
Optics Express | Year: 2011

In this study, a radial imaging capsule endoscope (RICE) system is designed, which differs from a conventional front imaging capsule endoscope (FICE) system. To observe the wrinkled intima of the intestine, which spreads without folding around the circumference of the capsule when a capsule endoscope with a diameter that slightly exceeds that of the intestine passes through it, the RICE uses a cone mirror, a radial window shell, and a focus optical module that comprise the radial imaging system. This concept was demonstrated in a packaged optical simulator. The RICE optical model also has been established and verified by many simulations and experiments. In minimizing the sagittal and tangential aberrations, the optical module of the RICE has achieved an F-number of 4.2, a viewing angle of 65.08°, and an RMS radius of the 4th to 6th fields of less than 17 um. A comparison of these characteristics with those of the focus optical module that is used in FICE lenses reveals that the spot size is 50% larger for each field, and the modulation transfer function (MTF) is remarkably improved from 7% to 36% at 100 lp/mm on the 5th field of the sagittal plane. © 2011 Optical Society of America.

Lin Y.-H.,National Chiao Tung University | Chen M.-S.,National Chiao Tung University | Lin H.-C.,National Chiao Tung University
Optics Express | Year: 2011

An electrically tunable-focusing optical zoom system using two composite LC lenses with a large zoom ratio is demonstrated. The optical principle is investigated. To enhance the electrically tunable focusing range of the negative lens power of the LC lens for a large zoom ratio, we adopted two composite LC lenses. Each composite LC lens consists of a sub-LC lens and a planar polymeric lens. The zoom ratio of the optical zooming system reaches ∼7.9:1 and the object can be zoomed in or zoomed out continuously at the objective distance of infinity to 10 cm. The potential applications are cell phones, cameras, telescope and pico projectors. © 2011 Optical Society of America.

Vedamalai M.,National Chiao Tung University | Wu S.-P.,National Chiao Tung University
Organic and Biomolecular Chemistry | Year: 2012

A new monostyryl boron dipyrromethene derivative (MS1) appended with two triazole units indicates the presence of Hg2+ among other metal ions with high selectivity by color change and red emission. Upon Hg2+ binding, the absorption band of MS1 is blue-shifted by 29 nm due to the inhibition of the intramolecular charge transfer from the nitrogen to the BODIPY, resulting in a color change from blue to purple. Significant fluorescence enhancement is observed with MS1 in the presence of Hg 2+; the metal ions Ag+, Ca2+, Cd2+, Co2+, Cu2+, Fe2+, Fe3+, K +, Mg2+, Mn2+, Ni2+, Pb 2+, and Zn2+ cause only minor changes in the fluorescence of the system. The apparent association constant (Ka) of Hg 2+ binding in MS1 is found to be 1.864 × 105 M -1. In addition, fluorescence microscopy experiments show that MS1 can be used as a fluorescent probe for detecting Hg2+ in living cells. © 2012 The Royal Society of Chemistry.

Pan J.-W.,National Chiao Tung University | Fan C.-W.,National Chiao Tung University
Optics Express | Year: 2011

We introduce a hybrid backlight module, which consists of a hybrid light guide plate (HLGP) and a brightness enhancement film (BEF). The HLGP comprises functions of a conventional light guide plate, a reflector, and a BEF. The HLGP allows one-dimensional rays to be collimated. We add a BEF above the HLGP, and let the crossed-dimension rays to be collimated. Comparing with the conventional edge-lit backlight module, the optical efficiency improves to 1.3-times and the on-axis luminance improves to 3.7-times by using the hybrid backlight module. © 2011 Optical Society of America.

Yeh C.H.,Industrial Technology Research Institute of Taiwan | Chow C.W.,National Chiao Tung University
Optics Express | Year: 2011

We propose and experimentally demonstrate a hybrid radio-over-fiber (ROF) wavelength division multiplexed and time division multiplexed passive optical network (WDM-TDM PON) architecture to mitigate Rayleigh backscattering (RB) interferometric beat noises. Here, only a single wavelength is needed at the central office (CO) to generate the downstream baseband data for optical wired application and optical millimeter-wave (mm-wave) signal for wireless application. The upstream signal is produced by remodulating the downstream signal. No optical filter is required at the optical network unit/remote antenna unit (ONU/RAU) to separate the optical wired and optical mm-wave signals. In the proposed network, 10 Gb/s differential phase shift keying (DPSK) signal is used for the downstream optical wired application and 2.5 Gb/s on-off keying (OOK) signal on 20 GHz carrier is used for the optical mm-wave signal. In each ONU, a reflective optical semiconductor amplifier (RSOA) is used to remodulate and produce a 2.5 Gb/s OOK format for upstream traffic. As the back-refection produced by the downstream DPSK signal and the upstream OOK signal is traveling in different fiber path, RB noise at the CO can be completely mitigated. © 2011 Optical Society of America.

Lo C.-W.,National Chiao Tung University | Wang C.-C.,National Chiao Tung University | Lu M.-C.,National Chiao Tung University
Advanced Functional Materials | Year: 2014

Condensation is a common phenomenon and is widely exploited in power generation and refrigeration devices. Although drop-wise condensation offers high heat and mass transfer rates, it is extremely difficult to maintain and control. In this study, the ability to spatially control heterogeneous nucleation on a superhydrophobic surface by manipulating the free energy barrier to nucleation through parameterizing regional roughness scale on the Si nanowire array-coated surface is reported. Water vapor preferentially condenses on the designed microgrooves on the Si nanowire surface and continuous shedding of the drop-wise condensate is observed on the surface. The nucleation site density can also be manipulated by tailoring the density of the microgroove on the surface. Moreover, the cycle time on the Si nanowire array with microgrooves is approximately ten times smaller than that on a plain Si surface. This suggests that potentially high heat and mass transfer rates can be achieved on the surface. The insight from this study has implications in enhancing energy efficiency in a wide range of thermal energy conversion systems. Spatial control of heterogeneous nucleation on superhydrophobic silicon nanowire array-coated surfaces is achieved by manipulating free energy barriers to nucleation through parameterizing regional roughness scale on the surface. Water droplets with a large contact angle preferentially nucleate on the designed microgrooves on the Si nanowire surface, whereas nucleation sites on an ordinary surface are randomly distributed. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kuo S.-W.,National Sun Yat - sen University | Chang F.-C.,National Chiao Tung University
Progress in Polymer Science (Oxford) | Year: 2011

This review describes the syntheses of polyhedral oligomeric silsesquioxane (T8-POSS) compounds, the miscibility of POSS derivatives and polymers, the preparation of both multifunctional and monofunctional monomers and polymers containing POSS including styryl-POSS, methacrylate-POSS, norbornyl-POSS, vinyl-POSS, epoxy-POSS, phenolic-POSS, benzoxazine-POSS, amine-POSS, and hydroxyl-POSS. The thermal, dynamic mechanical, electrical, and surface properties of POSS-related polymeric nanocomposites prepared from both monofunctional and multifunctional POSS monomers are discussed. In addition, we describe the applications of several high-performance POSS nanocomposites in such systems as light emitting diodes, liquid crystals, photo-resist materials, low-dielectric constant materials, self-assembled block copolymers, and nanoparticles. © 2011 Elsevier Ltd. All rights reserved.

Pao H.-T.,National Chiao Tung University | Tsai C.-M.,National Chiao Tung University
Energy | Year: 2011

This paper examines the dynamic relationships between pollutant emissions, energy consumption, and the output for Brazil during 1980-2007. The Grey prediction model (GM) is applied to predict three variables during 2008-2013. In the long-run equilibrium emissions appear to be both energy consumption and output inelastic, but energy is a more important determinant of emissions than output. This may be because Brazilian unsustainable land use and forestry contribute most to the country's greenhouse gas emissions. The findings of the inverted U-shaped relationships of both emissions-income and energy consumption-income imply that both environmental damage and energy consumption firstly increase with income, then stabilize, and eventually decline. The causality results indicate that there is a bidirectional strong causality running between income, energy consumption and emissions. In order to reduce emissions and to avoid a negative effect on the economic growth, Brazil should adopt the dual strategy of increasing investment in energy infrastructure and stepping up energy conservation policies to increase energy efficiency and reduce wastage of energy. The forecasting ability of GM is compared with the autoregressive integrated moving average (ARIMA) model over the out-of-sample period between 2002 and 2007. All of the optimal GMs and ARIMAs have a strong forecasting performance with MAPEs of less than 3%. © 2011 Elsevier Ltd.

Wei L.-Y.,National Chiao Tung University | Zheng Y.,Microsoft | Peng W.-C.,National Chiao Tung University
Proceedings of the ACM SIGKDD International Conference on Knowledge Discovery and Data Mining | Year: 2012

The advances in location-acquisition technologies have led to a myriad of spatial trajectories. These trajectories are usually generated at a low or an irregular frequency due to applications' characteristics or energy saving, leaving the routes between two consecutive points of a single trajectory uncertain (called an uncertain trajectory). In this paper, we present a Route Inference framework based on Collective Knowledge (abbreviated as RICK) to construct the popular routes from uncertain trajectories. Explicitly, given a location sequence and a time span, the RICK is able to construct the top-k routes which sequentially pass through the locations within the specified time span, by aggregating such uncertain trajectories in a mutual reinforcement way (i.e., uncertain + uncertain → certain). Our work can benefit trip planning, traffic management, and animal movement studies. The RICK comprises two components: routable graph construction and route inference. First, we explore the spatial and temporal characteristics of uncertain trajectories and construct a routable graph by collaborative learning among the uncertain trajectories. Second, in light of the routable graph, we propose a routing algorithm to construct the top-k routes according to a user-specified query. We have conducted extensive experiments on two real datasets, consisting of Foursquare check-in datasets and taxi trajectories. The results show that RICK is both effective and efficient. © 2012 ACM.

This paper addresses the impact of both economic growth and financial development on environmental degradation using a panel cointegration technique for the period between 1980 and 2007, except for Russia (1992-2007). In long-run equilibrium, CO2 emissions appear to be energy consumption elastic and FDI inelastic, and the results seem to support the Environmental Kuznets Curve (EKC) hypothesis. The causality results indicate that there exists strong bidirectional causality between emissions and FDI and unidirectional strong causality running from output to FDI. The evidence seems to support the pollution haven and both the halo and scale effects. Therefore, in attracting FDI, developing countries should strictly examine the qualifications for foreign investment or to promote environmental protection through the coordinated know-how and technological transfer with foreign companies to avoid environmental damage. Additionally, there exists strong output-emissions and output-energy consumption bidirectional causality, while there is unidirectional strong causality running from energy consumption to emissions. Overall, the method of managing both energy demand and FDI and increasing both investment in the energy supply and energy efficiency to reduce CO2 emissions and without compromising the country's competitiveness can be adopted by energy-dependent BRIC countries. © 2010 Elsevier Ltd.

Huang C.-H.,National Chiao Tung University | Chen T.-M.,National Chiao Tung University
Journal of Physical Chemistry C | Year: 2011

A novel single-composition white-emitting phosphor Ca 3Y(GaO) 3(BO 3) 4:Ce 3+,Mn 2+,Tb 3+ has been synthesized by a high-temperature solid-state reaction. The spectral overlap between the emission band of Ce 3+ and the excitation band of Mn 2+, which supports the occurrence of the energy transfer from Ce 3+ to Mn 2+, has been studied and demonstrated to be a resonant type via a dipole-quadrupole mechanism. Because there was no spectral overlap between the emission spectra of Ce 3+ and excitation band of Tb 3+ in our study, no energy transfer from Ce 3+ to Tb 3+ was observed, indicating that Ce 3+ and Tb 3+ were coexcited. Through effective resonance-type energy transfer and coexcitation, the chromaticity coordinates of Ca 3Y(GaO) 3(BO 3) 4:Ce 3+,Mn 2+,Tb 3+ phosphors can be tuned from (0.152, 0.061) for Ca 3Y(GaO) 3(BO 3) 4:Ce 3+ to (0.562, 0.408) for Ca 3Y(GaO) 3(BO 3) 4:Mn 2+, and eventually reaching (0.314, 0.573) for Ca 3Y(GaO) 3(BO 3) 4:Tb 3+. A white light-emitting diode (LED) was fabricated by using the white-emitting single-composition (Ca 0.97) 3(Y 0.92)(GaO) 3(BO 3) 4:0.01Ce 3+,0.03Mn 2+,0.07Tb 3+ pumped by a 365 nm UV-chip. Our results indicated that the CIE chromaticity coordinates and correlated color temperature (CCT) for white UV-LEDs were (0.31, 0.33) and 6524 K, respectively. Therefore, our novel white Ca 3Y(GaO) 3(BO 3) 4:Ce 3+,Mn 2+,Tb 3+ can serve as a key material for phosphor-converted white-light UV-LEDs. © 2011 American Chemical Society.

Wang C.-C.,National Chiao Tung University
Energy Conversion and Management | Year: 2011

The present study examines the heat transfer coefficients applicable for membrane distillation. In the available literatures, researchers often adopt some existing correlations and claim the suitability of these correlations to their test data or models. Unfortunately this approach is quite limited and questionable. This is subject to the influences of boundary conditions, geometrical configurations, entry flow conditions, as well as some influences from spacer or support. The simple way is to obtain the heat transfer coefficients from experimentation. However there is no direct experimental data for heat transfer coefficients being reported directly from the measurements. The main reasons are from the uncertainty of permeate side and of the comparatively large magnitude of membrane resistance. Additional minor influence is the effect of mass transfer on the heat transfer performance. In practice, the mass transfer effect is negligible provided the feed side temperature is low. To increase the accuracy of the measured feed side heat transfer coefficient, it is proposed in this study to exploit a modified Wilson plot technique. Through this approach, one can eliminate the uncertainty from permeate side and reduce the uncertainty in membrane to obtain a more reliable heat transfer coefficients at feed side from the experimentation. © 2010 Elsevier Ltd. All rights reserved.

Hsieh E.R.,National Chiao Tung University | Chung S.S.,National Chiao Tung University
Applied Physics Letters | Year: 2010

The source/drain in an n-channel metal-oxide-semiconductor field-effect transistor (nMOSFET) with solid phase epitaxial (SPE) implanted Si:C before the spacer formation is proposed. Compared to the conventional nMOSFET with SPE implanted Si:C after the spacer formation, it brings in proximity to the device channel and shows great improvement of electron mobility via the stronger tensile strain effect. Experimental measurements showed that the electron mobility in the proposed process is increased by 105% over that of the control devices. At a gate length of 40 nm, an increase of more than 67% for the drain current, comparing to those of the conventional Si:C source/drain nMOSFET, has been achieved. © 2010 American Institute of Physics.

Tsai Y.-D.,National Tsing Hua University | Wu X.N.,CAS Academy of Mathematics and Systems Science | Yang Y.,National Chiao Tung University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

We study the critical phenomena of Kerr-AdS black hole. Phase structures are observed at different temperatures, T L, T c1 and T c2 with various features. We discuss the thermal stability considering the isothermal compressibility and how phase transitions related to each other. The asymptotic value of the angular momentum also has an implication on separating stable and unstable part. Near critical temperature T c1, the order parameter is determined to calculate the critical exponents. All the critical exponents (α,β,γ,δ)=(0,12,1, 3) are identical to that of mean field systems. We plot the phase diagram near this critical point, and discuss the scaling symmetry of the free energy. © 2012 American Physical Society.

Lai H.-Y.,National Chiao Tung University | Chen C.-H.,National Chiao Tung University
Journal of Materials Chemistry | Year: 2012

We discovered a promising room-temperature CO sensing capability of Pt or Pd nanoparticle-functionalized In 2O 3 flower-like nanobundles (NBs) composed of parallel nanoparticle-chains. The highly branched In 2O 3 flower-like NBs synthesized through the process of hydrolysis of InCl 3 in NaBH 4 aqueous solution and the subsequent heat treatment provided an extremely porous matrix required for high-performance gas sensors. The Pt and Pd nanoparticles uniformly deposited on the In 2O 3 NBs evidently play a key role in enhancing the sensitivity and response, and most importantly lowering the operating temperature to 25 °C for the detection of CO gas. The present innovative hybrid nanostructures offer a potential platform for room-temperature oxide-based gas nanosensors. Moreover, the resulting sensing behaviours lead to a better understanding of using and designing such nanosensors for a number of gas sensory applications. © 2012 The Royal Society of Chemistry.

Wu S.-Y.,National Chiao Tung University
Journal of Superconductivity and Novel Magnetism | Year: 2016

A single static vortex in a holographic two-band superconductor is constructed. We investigate the effect of the interband coupling to the condensate profile. We estimate the first critical magnetic field, and compute characteristic lengths like penetration and coherence lengths and conclude both bands in our superconductor behave type II. © 2015, Springer Science+Business Media New York.

Huang K.Y.,Yuan Ze University | Huang K.Y.,Academia Sinica, Taiwan | Huang K.Y.,National Chiao Tung University
Database : the journal of biological databases and curation | Year: 2014

Protein phosphorylation catalyzed by kinases plays crucial roles in regulating a variety of intracellular processes. Owing to an increasing number of in vivo phosphorylation sites that have been identified by mass spectrometry (MS)-based proteomics, the RegPhos, available online at http://csb.cse.yzu.edu.tw/RegPhos2/, was developed to explore protein phosphorylation networks in human. In this update, we not only enhance the data content in human but also investigate kinase-substrate phosphorylation networks in mouse and rat. The experimentally validated phosphorylation sites as well as their catalytic kinases were extracted from public resources, and MS/MS phosphopeptides were manually curated from research articles. RegPhos 2.0 aims to provide a more comprehensive view of intracellular signaling networks by integrating the information of metabolic pathways and protein-protein interactions. A case study shows that analyzing the phosphoproteome profile of time-dependent cell activation obtained from Liquid chromatography-mass spectrometry (LC-MS/MS) analysis, the RegPhos deciphered not only the consistent scheme in B cell receptor (BCR) signaling pathway but also novel regulatory molecules that may involve in it. With an attempt to help users efficiently identify the candidate biomarkers in cancers, 30 microarray experiments, including 39 cancerous versus normal cells, were analyzed for detecting cancer-specific expressed genes coding for kinases and their substrates. Furthermore, this update features an improved web interface to facilitate convenient access to the exploration of phosphorylation networks for a group of genes/proteins. Database URL: http://csb.cse.yzu.edu.tw/RegPhos2/

Chen C.-T.,National Chiao Tung University | Chen Y.-C.,National Chiao Tung University
Chemical Communications | Year: 2010

A label free fluorescence method for rapid detection of the presence of phosphorylated peptides/proteins in sample solutions using functional magnetic nanoparticles (MNPs) as the detection probes is demonstrated. © 2010 The Royal Society of Chemistry.

Tiwari J.N.,Pohang University of Science and Technology | Tiwari R.N.,Toyota Technological Institute | Singh G.,National Chiao Tung University | Kim K.S.,Pohang University of Science and Technology
Nano Energy | Year: 2013

Continuous growth in global energy demand has sparked concerns about energy security and environmental sustainability. In the past two decades, attempts have been made in the development of innovative energy technologies. The direct methanol fuel cell (DMFC) is among the most promising alternative energy sources for the near future. Simple construction, compact design, high energy density and relatively high energy-conversion efficiency give the DMFC an advantage over other promising power sources in terms of portability. However, the translation of DMFCs into commercially successful products is precluded due to poor performance. In addition, low activity, poor durability and reliability and an expensive anode and cathode further discourage the application of DMFCs. In this regard, the present review article focuses on recent progress in the development of anode and cathode catalysts for DMFCs. The first part of the review discusses the recent developments in the synthesis of single-, double-, and multiple-component catalysts and new catalyst supports for anode electrodes. The section is followed by the chemical approaches employed to make alloys and composite catalysts, aiming to enhance their activity, reliability and durability for the methanol oxidation reaction. Finally, exciting new research that pushes the development of single-, double-, and multiple-component catalysts and new catalyst supports for cathode electrodes is introduced. In addition, size-, shape- and composition-dependent electrocatalysts that are advocated for methanol oxidation at the anode and oxygen reduction at the cathode are highlighted to illustrate the potential of the newly developed electrocatalysts for DMFC applications. Moreover, this article provides a comprehensive review of the experimental work that is devoted to understanding the fundamental problems and recent progress in the development of anode and cathode catalysts for DMFCs.© 2013 Elsevier Ltd.

Chiou Y.-C.,National Chiao Tung University | Fu C.,National Chiao Tung University
Accident Analysis and Prevention | Year: 2013

Since the factors contributing to crash frequency and severity usually differ, an integrated model under the multinomial generalized Poisson (MGP) architecture is proposed to analyze simultaneously crash frequency and severity - making estimation results increasingly efficient and useful. Considering the substitution pattern among severity levels and the shared error structure, four models are proposed and compared - the MGP model with or without error components (EMGP and MGP models, respectively) and two nested generalized Poisson models (NGP model). A case study based on accident data for Taiwan's No. 1 Freeway is conducted. The results show that the EMGP model has the best goodness-of-fit and prediction accuracy indices. Additionally, estimation results show that factors contributing to crash frequency and severity differ markedly. Safety improvement strategies are proposed accordingly. © 2012 Elsevier Ltd.

Sugiyama T.,Instrument Technology Research Center | Yuyama K.-I.,National Chiao Tung University | Masuhara H.,National Chiao Tung University
Accounts of Chemical Research | Year: 2012

Laser trapping has served as a useful tool in physics and biology, but, before our work, chemists had not paid much attention to this technique because molecules are too small to be trapped in solution at room temperature. In late 1980s, we demonstrated laser trapping of micrometer-sized particles, developed various methodologies for their manipulation, ablation, and patterning in solution, and elucidated their dynamics and mechanism. In the 1990s, we started laser trapping studies on polymers, micelles, dendrimers, and gold, as well as polymer nanoparticles. Many groups also reported laser trapping studies of nanoclusters, DNA, colloidal suspensions, etc. Following these research streams, we have explored new molecular phenomena induced by laser trapping. Gradient force leading to trapping, mass transfer by local heating, and molecular reorientation following laser polarization are intimately coupled with molecular cluster and aggregate formation due to their intermolecular interactions, which depend on whether the trapping position is at the interface/surface or in solution.In this Account, we summarize our systematic studies on laser trapping chemistry and present some new advances and our future perspectives. We describe the laser trapping of nanoparticles, polymers, and amino acid clusters in solution by focusing a continuous wave 1064 nm laser beam on the molecules of interest and consider their dynamics and mechanism. In dilute solution, nanoparticles with weak mutual interactions are individually trapped at the focal point, while laser trapping of nanoparticles in concentrated solution assembles and confines numerous particles at the focal spot. The assembly of polymers during their laser trapping extends out from the focal point because of the interpolymer interactions, heat transfer, and solvent flow. When the trapping laser is focused at an interface between a thin heavy water solution film of glycine and a glass substrate, the assembled molecules nucleate and evolve to a liquid-liquid phase separation, or they will crystallize if the trapping laser is focused on the solution surface. Laser trapping can induce spatiotemporally the liquid and solid nucleation of glycine, and the dense liquid droplet or crystal formed can grow to a bulk scale. We can control the polymorph of the formed glycine crystal selectively by tuning trapping laser polarization and power. These results provide a new approach to elucidate dynamics and mechanism of crystallization and are the fundamental basis for studying not only enantioselective crystallization but also confined polymerization, trapping dynamics by ultrashort laser pulses, and resonance effect in laser trapping. © 2012 American Chemical Society.

Su H.-C.,National Chiao Tung University | Cheng C.-Y.,National Chiao Tung University
Israel Journal of Chemistry | Year: 2014

Compared to organic light-emitting diodes, solid-state light-emitting electrochemical cells (LECs) exhibit advantages of simple device structures, low operation voltages, and compatibility with air-stable metal electrodes. Since the first demonstration of white LECs in 1997, the cells have been studied extensively, due to their potential applications in solid-state lighting. This article reviews the development of white LECs based on conjugated polymers and cationic transition metal complexes. Important achievements of each work on white LECs are highlighted. Finally, the outlook for future development of white LECs is discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tsai J.-L.,National Chiao Tung University | Tu J.-F.,National Chiao Tung University
Materials and Design | Year: 2010

The mechanical properties of graphite in the forms of single graphene layer and graphite flakes (containing several graphene layers) were investigated using molecular dynamics (MD) simulation. The in-plane properties, Young's modulus, Poisson's ratio, and shear modulus, were measured, respectively, by applying axial tensile stress and in-plane shear stress on the simulation box through the modified NPT ensemble. In order to validate the results, the conventional NVT ensemble with the applied uniform strain filed in the simulation box was adopted in the MD simulation. Results indicated that the modified NPT ensemble is capable of characterizing the material properties of atomistic structures with accuracy. In addition, it was found the graphene layers exhibit higher moduli than the graphite flakes; thus, it was suggested that the graphite flakes have to be expanded and exfoliated into numbers of single graphene layers in order to provide better reinforcement effect in nanocomposites. © 2009 Elsevier Ltd. All rights reserved.

Lee C.-M.,National Chiao Tung University | Tsui B.-Y.,National Chiao Tung University
IEEE Electron Device Letters | Year: 2010

A novel 30-nm gate-all-around (GAA) polycrystalline-silicon (poly-Si) nanowire (NW) thin-film transistor (TFT) is reported for the first time. Owing to the NW and GAA structure, the channel electric potential is well controlled by the gate electrode. After NH3 plasma treatment for defects passivation, the values of 0.97 V, 224 mV/dec., and 0.895 V/V of threshold voltage, subthreshold swing, and drain-induced barrier lowering are achieved, respectively. A high driving current of 459 μA/μm and an on-state/off-state current ratio of 5 ×107 are also obtained. These excellent characteristics indicate that the ultrasmall GAA NW poly-Si TFT would have the potential to be applied in the 3-D integrated-circuit or system-on-panel field. © 2010 IEEE.

Watanabe H.,National Chiao Tung University
IEEE Transactions on Electron Devices | Year: 2010

The single-electron general-purpose device simulator is improved to carry out a wide-range transient analysis from 1 ps to 10 years. We apply this simulator to a floating gate (FG) nonvolatile memory cell in order to simulate a degradation mode of data retention owing to the direct tunneling enhanced by the fixed charge stored by a local trap in an interpoly dielectric. The scaling impact of ideal high-K interpoly dielectric FG nonvolatile memory cell is also investigated. © 2006 IEEE.

Chen C.,National Chiao Tung University | Tong H.M.,Advanced Semiconductor Engineering Inc. | Tu K.N.,University of California at Los Angeles
Annual Review of Materials Research | Year: 2010

Pb-free solders have replaced Pb-containing SnPb solders in the electronic packaging industry due to environmental concerns. Both electromigration (EM) and thermomigration (TM) have serious reliability issues for fine-pitch Pb-free solder bumps in the flip-chip technology used in consumer electronic products. We review the unique features of EM and TM in flip-chip solder bumps, emphasizing the effects of current crowding and Joule heating. In addition, the challenges to a better understanding of EM and TM in Pb-free solders are discussed. For example, the anisotropic nature of Sn microstructure in Pb-free solders can enhance the dissolution rates of Ni and Cu in solders driven by EM and TM. © 2010 by Annual Reviews. All rights reserved.

Wang T.-W.,National Chiao Tung University | Su H.-C.,National Chiao Tung University
Organic Electronics: physics, materials, applications | Year: 2013

Techniques of probing for time-dependent evolution of recombination zone position in sandwiched light-emitting electrochemical cells (LECs) would be highly desired since they can provide direct experimental evidence to confirm altered carrier balance when device parameters are adjusted. However, direct imaging of recombination zones in thin emissive layers of sandwiched LECs could not be obtained easily. In this work, we propose an alternative way to extract evolution of recombination zone position in sandwiched LECs by utilizing microcavity effect. Recombination zone positions can be estimated by fitting the measured electroluminescence spectra to simulated output spectra based on microcavity effect and properly adjusted emissive zone positions. With this tool, effects of modified carrier transport and carrier injection on performance of LECs are studied and significantly altered carrier balance can be measured, revealing that microcavity effect is useful in tracing evolution of recombination zone position in sandwiched LECs. © 2013 Elsevier B.V.

Huang H.-C.,National University of Kaohsiung | Fang W.-C.,National Chiao Tung University
Simulation Modelling Practice and Theory | Year: 2010

In this paper, we propose a practical application for copyright protection of images with watermarking. The EXIF metadata of images and error-control codes are integrated into our algorithm and corresponding applications. Application for robust watermarking is one of the major branches in digital rights management (DRM) systems and digital forensics. Here, we focus on the copyright protection for images taken by ordinary cameras. By use of robust watermarking, it generally alters selected coefficients of the contents to accomplish the embedding process. Should the received image be in question, the watermark embedded beforehand can be extracted to indicate the copyright owner of such an image. We consider not only the image contents itself, but we also employ the EXIF metadata, which serves as the role of watermark, to be integrated into our scheme to make copyright protection possible. Moreover, for enhancing the performance for copyright protection, channel coding is employed and better protection capability can be expected. Taking the manufacturer, camera model, date and time stamp, and other important information in the EXIF metadata into account, conventional watermarking techniques can be applied to ordinary pictures taken by ourselves, and watermarked images with good quality can be produced. Even when the marked image has been intentionally modified, the original EXIF with selected information can mostly be recovered from the channel decoding process. Simulation results present the effectiveness of such an implementation. © 2009 Elsevier B.V. All rights reserved.

Lu H.-F.F.,National Chiao Tung University
IEEE Transactions on Information Theory | Year: 2016

A novel transmission scheme for cooperative relay networks is presented in this paper. The proposed scheme is based on the non-orthogonal selection decode-and-forward protocol with an additional assumption of having a low rate feedback channel from the destination to relays. Benefited from the feedback information, an optimal distributed code that has an extremely short delay equal to four is constructed, and the same code is applicable to networks with the arbitrary number of relays to yield optimal cooperative diversity. The proposed code is sphere decodable with a decoding complexity again independent of the number of relays in high SNR regime. In particular, when operating at multiplexing gain ≥(1/2), the lattice decoder at the destination has a zero complexity exponent, meaning a constant decoding complexity and independent of transmission rate. Analyses for the decoding complexity of other existing diversity-optimal distributed codes are also provided. It is shown that these codes have a linear growth in delay and an exponential growth in decoding complexity as the number of relays increases. © 2016 IEEE.

Chang L.-P.,National Chiao Tung University
IEEE Transactions on Computers | Year: 2010

Replacing power-hungry disks with NAND-flash-based solid-state disks (SSDs) is a recently emerging trend in flash-memory applications. One important SSD design issue is achieving a good balance between cost, performance, and lifetime. This study introduces a hybrid approach to large SSDs that combines MLC NAND flash and SLC NAND flash. Each of these flash architectures has its own drawbacks and benefits, and this study proposes that the two can complement each other. However, there are technical challenges pertaining to data placement, data migration, and wear leveling in heterogeneous NAND flash. The experimental results of our study show that combining 256 MB SLC flash with 20 GB MLC flash produces a hybrid SSD. This hybrid SSD is 1.8 times faster than a purely MLC-flash-based SSD in terms of average response time and improves energy consumption by 46 percent. The proposed hybrid SSD costs only four percent more than a purely MLC-flash-based SSD. The extra cost of a hybrid SSD is very limited and rewarding. © 2006 IEEE.

Pan J.-W.,National Chiao Tung University | Pan J.-W.,Chi Mei Medical Center | Shih C.-H.,National Chiao Tung University
Optics Express | Year: 2014

We proposed a design for a LASER pico-projector with a low speckle contrast value and high contrast ratio that maintains system efficiency. The method for speckle contrast reduction utilizes two diffusers and a Voice Coil Motor (VCM) oscillator. The two different diffusers for a high contrast ratio and high system efficiency can be divided into two categories. In Category 1, the speckle contrast value can be decreased to 2.80% by using a circular symmetric diffuser. At the same time, the fullon/ full-off (FO:FO) contrast ratio can be maintained within 1200:1-1300:1, but the system efficiency decreases 1.50%. In Category 2, the speckle contrast value can be reduced to 6.50% by using an elliptically scattering diffuser. At the same time, the FO:FO contrast ratio can be maintained within 1300:1-1400:1, and the system efficiency decreases by only 1.00%. © 2014 Optical Society of America.

Sung J.-Y.,National Chiao Tung University | Chow C.-W.,National Chiao Tung University | Yeh C.-H.,Feng Chia University
Optics Express | Year: 2014

Optical blue filter is usually regarded as a critical optical component for high speed phosphor-based white light emitting diode (LED) visible-light- communication (VLC). However, the optical blue filter plays different roles in VLC when using modulations of on-off keying (OOK) or discrete multi-tone (DMT). We show that in the DMT VLC system, the blue optical filter may be unnecessary, and even degrade the transmission performance (by reducing the optical signal-to-noise ratio (SNR)). Analyses and verifications by experiments are performed. To the best of our knowledge, this is the first time the function of blue filters in VLC is explicitly analyzed. © 2014 Optical Society of America.

Chen S.-H.,National Chiao Tung University | Chow C.-W.,National Chiao Tung University
Optics Express | Year: 2014

A novel color-filter-free visible-light communication (VLC) system using red-green-blue (RGB) light emitting diode (LED) and mobilephone camera is proposed and demonstrated for the first time. A feature matching method, which is based on the scale-invariant feature transform (SIFT) algorithm for the received grayscale image is used instead of the chromatic information decoding method. The proposed method is simple and saves the computation complexity. The signal processing is based on the grayscale image computation; hence neither color-filter nor chromatic channel information is required. A proof-of-concept experiment is performed and high performance channel recognition is achieved. © 2014 Optical Society of America.

Chen C.-P.,Industrial Technology Research Institute of Taiwan | Chen Y.-D.,Industrial Technology Research Institute of Taiwan | Chuang S.-C.,National Chiao Tung University
Advanced Materials | Year: 2011

Inverted OPV devices based on sol-gel derived vanadium oxides (VO x) as an interfacial layer are demonstrated. The VOx shows excellent characteristics as a hole-transporting and protecting layer. The constructed devices exhibit enhanced performance with the studied polymers and are highly durable under accelerated conditions for long time periods. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sung J.-Y.,National Chiao Tung University | Chow C.-W.,National Chiao Tung University | Yeh C.-H.,Industrial Technology Research Institute of Taiwan | Yeh C.-H.,Fu Jen Catholic University
Optics Express | Year: 2014

Visible light communication (VLC) using LEDs has attracted significant attention recently for the future secure, license-free and electromagnetic- interference (EMI)-free optical wireless communication. Dimming technique in LED lamp is advantageous for energy efficiency. Color control can be performed in the red-green-blue (RGB) LEDs by using dimming technique. It is highly desirable to employ dimming technique to provide simultaneous color and dimming control and high speed VLC. Here, we proposed and demonstrated a LED dimming control using dimming-discrete-multi-tone (DMT) modulation. High speed DMT-based VLC with simultaneous color and dimming control is demonstrated for the first time to the best of our knowledge. Demonstration and analyses for several modulation conditions and transmission distances are performed, for instance, demonstrating the data rate of 103.5 Mb/s (using RGB LED) with fast Fourier transform (FFT) size of 512. © 2014 Optical Society of America.

Panda D.,National Chiao Tung University | Huang C.-Y.,National Chiao Tung University | Tseng T.-Y.,National Chiao Tung University
Applied Physics Letters | Year: 2012

Resistive switching behavior of the Ti/HfO 2:NiSi:HfO 2/Pt memory structure is investigated. Auger electron spectroscopy analysis indicates no metal diffusion from the electrodes and silicide layer on high-k film. Cross-sectional transmission electron microscopic micrographs revealed the thicknesses of the HfO 2 and silicide layer. Significant decrease of forming voltage is observed for the 550 C, 1 min annealed device embedded with nickel silicide (NiSi) layers. Entire device shows bipolar switching properties with very low set/reset voltage. The optimized annealed device with NiSi embedded layer exhibits improved memory performances such as good on/off ratio (>10 2), long retention more than 10 4s, and reasonable endurance (>10 3 cycles). A conducting filament model based on two stacks structure is employed to well explain the switching behaviors. © 2012 American Institute of Physics.

Chen Y.-L.,National Chiao Tung University | Chang C.-Y.,National Chiao Tung University | Cheng Y.-J.,National Chiao Tung University | Hsu C.-S.,National Chiao Tung University
Chemistry of Materials | Year: 2012

We have developed a new heptacyclic benzodi(cyclopentadithiophene) (BDCPDT) unit, where 3,7-positions of the central benzo[1,2-b:4,5-b′]dithiophenes (BDT) subunit are covalently rigidified with 3-positons of the two external thiophenes by two carbon bridges, forming two external CPDT rings that share two thiophene rings with the central BDT core. The distannyl-BDCPDT building block was copolymerized with 1,3-dibromo-thieno[3,4-c]pyrrole-4,6-dione (TPD) by Stille polymerization to afford a new alternating donor-acceptor copolymer PBDCPDT-TPD. The implementation of forced planarization greatly suppresses the interannular twisting to extend the effective conjugated length and preserve the interactions between the donor and acceptor segments. The device using the PBDCPDT-TPD/PC 71BM (1:3 in wt%) blend processed with dimethyl sulfoxide as an additive delivered a marked PCE of 6.6% which represents a significant enhancement compared to the device using the corresponding nonfused polymer analogue with a PCE of 0.2%. © 2012 American Chemical Society.

Lin J.-Y.,National Chiao Tung University | Chen Y.-P.,National Chiao Tung University
IEEE Transactions on Evolutionary Computation | Year: 2011

The synergy between exploration and exploitation has been a prominent issue in optimization. The rise of memetic algorithms, a category of optimization techniques which feature the explicit exploration-exploitation coordination, much accentuates this issue. While memetic algorithms have achieved remarkable success in a wide range of real-world applications, the key to successful exploration-exploitation synergies still remains obscure as conclusions drawn from empirical results or theoretical derivations are usually quite algorithm specific and/or problem dependent. This paper aims to provide a theoretical model that can depict the collaboration between global search and local search in memetic computation on a broad class of objective functions. In the proposed model, the interaction between global search and local search creates a set of local search zones, in which the global optimal points reside, within the search space. Based on such a concept, the quasi-basin class (QBC) which categorizes problems according to the distribution of their local search zones is adopted. The subthreshold seeker, taken as a representative archetype of memetic algorithms, is analyzed on various QBCs to develop a general model for memetic algorithms. As the proposed model not only well describes the expected time for a simple memetic algorithm to find the optimal point on different QBCs but also consists with the observations made in previous studies in the literature, the proposed model may reveal important insights to the design of memetic algorithms in general. © 2011 IEEE.

Chiao M.-L.,National Chiao Tung University | Chang D.-W.,National Cheng Kung University
IEEE Transactions on Computers | Year: 2011

A Flash Translation Layer (FTL) provides a block device interface on top of flash memory to support disk-based file systems. Due to the erase-before-write feature of flash memory, an FTL usually performs out-of-place updates and uses a cleaning procedure to reclaim stale data. A hybrid address translation (HAT)-based FTL combines coarse-grained and fine-grained address translation to achieve good performance while keeping the size of the mapping information small. In this paper, we propose a new HAT-based FTL, called ROSE, which includes three novel techniques for reducing the cleaning cost. First, it reduces high-cost reclamation by preventing data in an entire-block sequential write from being placed into multiple physical blocks while eliminating the cleaning cost resulting from mispredicting random or semisequential writes as sequential ones. Second, it uses a merge-aware cleaning policy that considers both the block age and the merge cost in a HAT-based FTL for improving the cleaning efficiency. Third, it delays the erasure of obsolete blocks and reuses their free pages for buffering more writes. Simulation results show that the proposed FTL outperforms existing HAT-based FTLs in terms of both cleaning cost and flash write time by up to 47 times and 1.6 times, respectively. © 2011 IEEE.

Lin C.-C.,National Chiao Tung University | Yang C.-H.,National Cheng Kung University | Shyua J.Z.,National Chiao Tung University
Energy Policy | Year: 2013

Utilities are increasing their investment in smart grid technologies because of the rising demand for electricity, the aging transmission and distribution infrastructure in developed countries and the need for real-time visibility of energy supply and demand to optimize service reliability and cost. Government policies are contributing to this rising investment in the smart grid in many countries around the globe. Using Rothwell and Zegveld's innovation policy framework as a starting point, this paper compares innovation policy in smart grids across the Pacific; specifically, China and the USA. This research describes the policy tools used by both countries and presents results that indicate national preferences for innovation policy that differ in the ways in which they are linked with the state of the power system. China has preferred to use "supply-side policy," which focuses on "public enterprise, scientific and technical development and legal regulation." The USA has preferred to use "environmental-side policy," which focuses on "scientific and technical development, financial, political and public enterprise." This paper also describes in detail a number of innovation policies being pursued in the smart grid industry in both China and the USA. © 2013 Elsevier Ltd.

Wang H.-F.,National Chiao Tung University | Wu S.-P.,National Chiao Tung University
Tetrahedron | Year: 2013

Three new pyrene derivatives (MS1, MS2, and MS3) containing two triazole units exhibited fluorescence quenching in the presence of Hg2+ ions. Other metal ions Ag+, Ca2+, Cd2+, Co 2+, Cu2+, Fe2+, Fe3+, K+, Mg2+, Mn2+, Na+, Ni2+, Pb 2+, Rb+, and Zn2+ produced only minor changes in the fluorescence of MS1, MS2, and MS3. The binding ratio of the chemosensor-Hg2+ complexes was found to be 1:1 according to Job plot experiments. The association constants (Ka) of chemosensor-Hg 2+ complexes were found to be 1.68×103 M -1 (MS1), 1.57×103 M-1 (MS2), and 1.52×103 M-1 (MS3), respectively. Moreover, fluorescence microscopy experiments showed that MS1 could be used as a fluorescent probe for detecting Hg2+ in living cells. © 2013 Elsevier Ltd. All rights reserved.

Chang Y.-C.,National Chiao Tung University | Jen T.-H.,National Chiao Tung University | Ting C.-H.,National Chiao Tung University | Huang Y.-P.,National Chiao Tung University
Optics Express | Year: 2014

A 2D/3D switchable and rotatable autostereoscopic display using a high-resistance liquid-crystal (Hi-R LC) lens array is investigated in this paper. Using high-resistance layers in an LC cell, a gradient electric-field distribution can be formed, which can provide a better lens-like shape of the refractive-index distribution. The advantages of the Hi-R LC lens array are its 2D/3D switchability, rotatability (in the horizontal and vertical directions), low driving voltage (∼2 volts) and fast response (∼0.6 second). In addition, the Hi-R LC lens array requires only a very simple fabrication process. © 2014 Optical Society of America.

Lin S.-S.,National Chiao Tung University | Hwang S.-K.,National Cheng Kung University | Liu J.-M.,National Chiao Tung University | Liu J.-M.,University of California at Los Angeles
Optics Express | Year: 2014

Supercontinuum generation in a highly nonlinear fiber pumped by noise-like pulses from an erbium-doped fiber ring laser is investigated. To generate ultrabroad spectra, a fiber amplifier is used to boost the power launched into the highly nonlinear fiber. After amplification, not only the average power of the noise-like pulses is enhanced but the spectrum of the pulses is also broadened due to nonlinear effects in the fiber amplifier. This leads to a reduction of the peak duration in their autocorrelation trace, suggesting a similar extent of pulse compression; by contrast, the pedestal duration increases only slightly, suggesting that the noise-like characteristic is maintained. By controlling the pump power of the fiber amplifier, the compression ratio of the noise-like pulse duration can be adjusted. Due to the pulse compression, supercontinuum generation with a broader spectrum is therefore feasible at a given average power level of the noise-like pulses launched into the highly nonlinear fiber. As a result, supercontinuum generation with an optical spectrum spanning from 1208 to 2111 nm is achieved using a 1-m nonlinear fiber pumped by amplified noise-like pulses of 15.5 MHz repetition rate at an average power of 202 mW. © 2014 Optical Society of America.

Hsiao Y.-C.,National Chiao Tung University | Wang H.-T.,National Chiao Tung University | Lee W.,National Chiao Tung University
Optics Express | Year: 2014

Photonic defect modes induced by in situ formation of an ill-defined defect layer is demonstrated in a cholesteric liquid crystal (CLC). The local deformation of the one-dimensionally periodic helical structure is achieved by means of the thermodielectric effect, which alters the pitch in the middle of the cholesteric structure. The defect-mode peak in the photonic band gap appears in the transmission spectrum only when the incident circularly polarized light has the same handedness as that of the CLC structure. The wavelength of the deformation-induced defect mode can be tuned upon varying the dielectric heating power by simply applying a frequency-modulated voltage. © 2014 Optical Society of America.

Pei T.-H.,National Chiao Tung University | Thiyagu S.,National Chung Hsing University | Pei Z.,National Chung Hsing University
Applied Physics Letters | Year: 2011

We fabricated large-area, vertically aligned silicon nanowire (SiNW) arrays on Si substrates employing catalytic etching on a polystyrene nanosphere template. The density of SiNWs was as high as 1010/cm2, and the bottom radii of SiNWs ranged between 30 and 60 nm. The reflection from the SiNW layer was approximately 0.1 over the spectral range of 300-800 nm for SiNWs longer than 750 nm. Effective medium theory was applied to explain this extremely low reflection, and it was confirmed that the incident light scatters randomly inside cone-like SiNWs, which lengthens the actual traveling path of light. © 2011 American Institute of Physics.

Satapathy R.,National Chiao Tung University | Wu Y.-H.,National Chiao Tung University | Lin H.-C.,National Chiao Tung University
Organic Letters | Year: 2012

Novel thieno-imidazole based polymer P showed both colorimetric and ratiometric detections of Hg2+ as well as fluorometric detection of Zn2+ via fluorescence turn-on response with augmented lifetime. Its model polymer M did not show any such sensing capability under similar conditions, which further confirmed the unique sensitivity of P toward Hg 2+ and Zn2+ via the chelation of metal ions to both "S" and "N" heteroatoms. © 2012 American Chemical Society.

Tseng W.-H.,National Chiao Tung University | Fan C.-W.,National Chiao Tung University | Wu J.-T.,National Chiao Tung University
Digest of Technical Papers - IEEE International Solid-State Circuits Conference | Year: 2011

The current-steering DACs are commonly used in generating high-frequency signals [1-4]. A current-steering DAC comprises current cells of various sizes. Each of them contains a current source and a current switch. The DAC static linearity, specified as differential nonlinearity (DNL) and integral nonlinearity (INL), is mainly determined by the mutual matching and the output resistance of the current sources. The DAC also exhibits dynamic distortion. It is manifested as spurious-free dynamic range (SFDR) degradation. The SFDR decreases rapidly with increasing input frequency. There are two major sources of dynamic distortion, code-dependent switching transients (CDST) and code-dependent output-loading variation (CDLV). Switching transients are temporal disturbances in DAC output when the current switches in current cells make transitions. The output loading of a DAC varies when the output impedances of current cells change due to the transposition of their current switches. This DAC applies a digital random return-to-zero (DRRZ) technique to mitigate the CDST effect. Compact current cells are designed to minimize the CDLV effect. The current mismatches of the current cells are corrected by background calibration. © 2011 IEEE.

Cheng C.H.,National Tsing Hua University | Chin A.,National Chiao Tung University | Yeh F.S.,National Tsing Hua University
Applied Physics Letters | Year: 2011

We report a high performance and low-power operated resistive memory. Using stacked covalent-bond-dielectric GeOx on metal-oxide SrTiO x to form the cost-effective Ni/ GeOx / SrTiOx /TaN resistive random access memory, ultralow set power of small 1 μW (0.9 μA at 1.2 V), reset power of 13 pW (0.13 nA at 0.1 V), fast 50 ns switching time and good 106 cycling endurance are realized. © 2011 American Institute of Physics.

Lin H.-C.,National Chiao Tung University | Lin Y.-H.,National Chiao Tung University
Applied Physics Letters | Year: 2011

An electrically tunable focusing liquid crystal (LC) lens with a built-in planar polymeric lens with a short focal length (∼4.41 to 8.82 cm) is demonstrated. The focal length of the LC lens is contributed by two parts: one is the LC layer and the other is planar polymeric layer. In the image system, the object can be continuously imaged by the LC lens when the object is at the objective distance from 360 to 17 cm as the voltage is switched from 0 to 35Vrms. The image performance is also demonstrated. The applications are cell phones, and cameras © 2011 American Institute of Physics.

Lin Y.-F.,National Chiao Tung University | Hsu Y.-J.,National Chiao Tung University
Applied Catalysis B: Environmental | Year: 2013

Semiconductor nanoheterostructures with type-II band offset have exhibited unique optoelectronic properties that are beneficial to photoconversion applications. Debatable arguments however exist in the literature for interpreting the most enhanced photocatalytic performance of type-II semiconductor nanoheterostructures when an optimal content of the constituents is employed. In this work, time-resolved photoluminescence is used to investigate the interfacial charge carrier dynamics for CdSnO3-decorated CdS nanowires, a prototype type-II nanoheterostructures system, with varying CdSnO3 contents. Our results show that the CdSnO3 content of 2.5at% rendered CdS-CdSnO3 NWs the most significant charge carrier separation, above which electron-hole recombination across CdS/CdSnO3 interface mediated carrier transfer to compromise the overall charge separation efficiency. The carrier dynamics results are in good accordance with that of photoconversion performance evaluation in dye photodegradation, which assists in resolving the very critical but still controversial issue as to the factors causing the depressed photocatalytic efficiency of type-II nanoheterostructures when the constituent content exceeds the optimal value. © 2012 Elsevier B.V.

Chow C.W.,National Chiao Tung University | Lin Y.H.,National Chiao Tung University
Optics Express | Year: 2012

To provide broadband services in a single and low cost perform, the convergent optical wired and wireless access network is promising. Here, we propose and demonstrate a convergent optical wired and wireless long-reach access networks based on orthogonal wavelength division multiplexing (WDM). Both the baseband signal and the radio-over-fiber (ROF) signal are multiplexed and de-multiplexed in optical domain, hence it is simple and the operation speed is not limited by the electronic bottleneck caused by the digital signal processing (DSP). Error-free demultiplexing and down-conversion can be achieved for all the signals after 60 km (long-reach) fiber transmission. The scalability of the system for higher bit-rate (60 GHz) is also simulated and discussed. © 2012 Optical Society of America.

Kuo H.-Y.,National Chiao Tung University
Smart Materials and Structures | Year: 2013

This paper studies the effective behavior of piezoelectric and piezomagnetic circular fibrous composites with imperfect interfaces under longitudinal shear with in-plane electromagnetic fields. Two kinds of imperfect contact are investigated: mechanically stiff and dielectrically/magnetically highly conducting interfaces, and mechanically compliant and dielectrically/magnetically weakly conducting interfaces. For the former case, the potential field is continuous, while the normal component of the flux undergoes a discontinuity across the interface. For the latter case, the normal component of the flux is continuous, while there is a jump of potential field at such a contact. The classic work of Rayleigh (1892 Phil. Mag. 34 481-502) in a periodic conductive perfect composite is generalized to the current coupled magnetoelectroelastic composites with imperfect interfaces. It is shown that the expression of the effective property has exactly the same form as that in the ideal coupling composite. Finally, this method is used to study BaTiO 3-CoFe2O4 composites and provide insights into enhancing the effective magnetoelectric voltage coefficient by properly choosing the interface. © 2013 IOP Publishing Ltd.

Chien M.-C.,National Chiao Tung University | Tien C.-H.,National Chiao Tung University
Optics Express | Year: 2012

LEDs have changed the concept of illumination not only in an expectation of the highest electroluminance efficiency but also in tremendous chances for smart lighting applications. With a cluster mixing, many studies were addressed to strategically manipulate the chromaticity point, system efficiency and color rendering performance according to different operational purposes. In this paper, we add an additional thermal function to extend the operational thermal window of a pentachromatic R/G/B/A/CW light engine over a chromaticity from 2800K to 8000K. The proposed model is experimentally validated to offer a full operable range in ambient temperature (Ta = 10° to 100°C) associated with high color quality scale (above 85 points) as well as high luminous efficiency (above 100 lm/watt). © 2012 Optical Society of America.

Liu K.K.,National Chiao Tung University
Nanotechnology | Year: 2010

A nanoparticle-conjugated cancer drug provides a novel strategy for cancer therapy. In this study, we manipulated nanodiamond (ND), a carbon nanomaterial, to covalently link paclitaxel for cancer drug delivery and therapy. Paclitaxel was bound to the surface of 3-5 nm sized ND through a succession of chemical modifications. The ND-paclitaxel conjugation was measured by atomic force microscope and nuclear magnetic resonance spectroscopy, and confirmed with infrared spectroscopy by the detection of deuterated paclitaxel. Treatment with 0.1-50 microg ml(-1) ND-paclitaxel for 48 h significantly reduced the cell viability in the A549 human lung carcinoma cells. ND-paclitaxel induced both mitotic arrest and apoptosis in A549 cells. However, ND alone or denatured ND-paclitaxel (after treatment with strong alkaline solution, 1 M NaOH) did not induce the damage effects on A549 cells. ND-paclitaxel was taken into lung cancer cells in a concentration-dependent manner using flow cytometer analysis. The ND-paclitaxel particles were located in the microtubules and cytoplasm of A549 cells observed by confocal microscopy. Furthermore, ND-paclitaxel markedly blocked the tumor growth and formation of lung cancer cells in xenograft SCID mice. Together, we provide a functional covalent conjugation of ND-paclitaxel, which can be delivered into lung carcinoma cells and preserves the anticancer activities on the induction of mitotic blockage, apoptosis and anti-tumorigenesis.

Liu Y.L.,National Chiao Tung University | Sun K.W.,National Chiao Tung University
Applied Physics Letters | Year: 2011

In this letter, we coupled nanodiamonds (NDs) with gold nanoparticles of different sizes using two complementary DNA sequences. After hybridizing the gold nanoparticles on the NDs, we observed the enhancement of the photoluminescence (PL) signals originating from the nitrogen-vacancy (N-V) center of the ND. The enhancement was attributed to the plasmon field created by the gold nanoparticles. The line shape of the enhanced PL spectra was also affected by the sizes of the attached nanoparticles due to their different resonant plasma frequencies. The signal enhancement can be used as an indexing tool for biosensing applications. © 2011 American Institute of Physics.

Chen C.-H.,National Chiao Tung University
Optics Letters | Year: 2014

We theoretically present the analysis and design of a nanoplasmonic bandpass filter with flat-top spectral characteristics by cascading a series of directly connected rectangular ring resonators based on metal-insulator-metal waveguides. Analyzed by the equivalent lumped circuit model of the transmission line to plasmonic waveguides, the transmission properties of a symmetric rectangular ring resonator with the directly connected input and output waveguides are approximately the same as that of a Fabry-Perot resonator. Then the thin-film design methodology is applied to realize a plasmonic bandpass filter with the squared passband. An example of cascaded tworectangular ring resonator structure is numerically demonstrated by using the transmission line model and 2D finite difference time domain method. © 2014 Optical Society of America.

Chen W.-H.,National Ilan University | Chen Y.-C.,National Chiao Tung University | Lin J.-G.,National Chiao Tung University
Bioresource Technology | Year: 2013

The study aims to investigate a cost-effective approach to convert non-pretreated rice straw hydrolysate into biobutanol. The influences of the initial cell concentration and incubation temperature on biobutanol production were evaluated under both sterile and non-sterile conditions. Results indicate that 100% glucose utilization could be achieved for initial cell concentrations greater than 2100. mg/L under both sterile and non-sterile conditions. Regression analyses resolve that under the sterile condition, the maximum butanol productivity of 1.45. g/L/d was projected at 1.96. g/L of cells and 32.3. °C, while the maximum butanol yield of 0.22. g/g was predicted at 2.01. g/L of cells and 26.3. °C. These two maximum values could not be projected by the regression analyses for the non-sterile condition. However, this study confirms that a high initial cell concentration of Clostridium saccharoperbutylacetonicum N1-4 can minimize interference from other microbes so that non-sterile biobutanol production is comparable to sterile biobutanol production. © 2012 Elsevier Ltd.

Tsai M.-T.,Chang Gung University | Chan M.-C.,National Chiao Tung University | Chan M.-C.,Chi Mei Medical Center
Optics Letters | Year: 2014

Simultaneous multispectral generation in 0.8, 1.0, and 1.3 μm wavelength ranges by efficient energy conversions of 1.0 μm wavelength femtosecond pulses through a nonlinear fiber was reported. The output spectral range of this multispectral light source was composed of 0.6-0.9 μm blue-shifted Cherenkov radiation (CR), 1.0 μm residual pump, and 1.1-1.7 μm red-shifted soliton self-frequency shift (SSFS) with more than 1 mW/nm power-spectral densities. Output characteristics of the multispectral light source were then quantitatively analyzed and the central wavelengths of CR and SSFS emissions can be further easily adjusted by changing the input power into wavelength conversion fiber. Example spectral-domain optical coherence tomography (OCT) images of an IR card and finger skin were also performed with the demonstrated source. Due to the advantages of its simplicity, easily operated, and wavelength tunability, the reported multispectral source could be widely applicable for various spectroscopic OCT applications. © 2014 Optical Society of America.

Tsao S.-L.,National Chiao Tung University | Cheng C.-M.,National Chiao Tung University
IEEE Communications Magazine | Year: 2011

Decentralized traffic information systems realize real-time traffic information services without the need for a server infrastructure. However, existing systems rely on either the vehicular ad hoc network or application-layer peer-to-peer protocols over a broadband wireless network suffering from low lookup success rate, high lookup latency, and maintenance overhead of the P2P network. This article proposes a two-tier VANET/P2P architecture that exploits both VANET and P2P technology. In the low tier, vehicles form a VANET via intervehicle communication to exchange traffic information. On top of the VANET, a portion of the vehicles further establish a P2P overlay through a broadband wireless infrastructure to mitigate the disconnectivity problems of the VANET. Simulation results demonstrate that the two-tier architecture can significantly improve the lookup success rate compared to the single-tier VANET systems while reducing lookup latency and maintenance overhead compared to the single-tier P2P systems. © 2010 IEEE.

Ramirez H.Y.,National Chiao Tung University | Cheng S.-J.,National Chiao Tung University
Physical Review Letters | Year: 2010

We theoretically study the effects of bias-controlled interdot tunneling in vertically coupled quantum dots on the emission properties of spin excitons in various bias-controlled tunneling regimes. As a main result, we predict substantial reduction of optical fine-structure splitting without any drop in the optical oscillator strength for the coupled dots with high tunneling rates. This special reduction diminishes the distinguishability of polarized decay paths in cascade emission processes suggesting the use of stacked quantum-dot molecules as entangled photon-pair sources. © 2010 The American Physical Society.

Tsai S.-H.,National Chiao Tung University
IEEE Transactions on Wireless Communications | Year: 2011

The beamforming vectors of an equal gain transmission (EGT) contains phase information only and thereby enjoys several implementational advantages when compared to the optimal scheme, i.e. maximum ratio transmission (MRT). The implementational advantages make EGT a promising solution for simple transceiver design while offering a performance comparable to that of MRT. This solution motivates us to explore how close the performance can be between EGT and MRT. The maximum SNR loss between EGT and MRT is known to be 1.05 dB in MISO channels. However, little is known about the SNR loss in MIMO channels, since no closed-form solution is available for the best EGT in MIMO channels. In this work, a suboptimal closed-form EGT design for MIMO channels is proposed and its performance is analyzed. Interestingly, the maximum SNR loss between the proposed EGT and the MRT (both employing MRC in receiver) in MIMO channels is shown to be approximately 1.05 dB as well. Moreover, instead of applying conventional all transmit antennas, this study proposes to adopt antenna selection, to further improve the performance of EGT. Two antenna selection algorithms are proposed and the corresponding performance is analyzed. When the proposed antenna selection algorithms are applied to EGT, the SNR loss between EGT and MRT can be reduced to as low as 0.45-0.65 dB, with the numbers of transmit antennas ranging from 4 to 8. One of the proposals with fixed number of transmit antennas not only outperforms conventional EGT but also requires fewer number of RF (radio frequency) components; also, it employs constant power in each transmit antenna like EGT does. As a result, hardware complexity can be reduced by this proposal. Furthermore, design strategies to apply the proposed EGT and antenna selection algorithms in systems with limited feedback are also suggested. © 2011 IEEE.

Li S.-Y.,National Chiao Tung University | Ge Z.-M.,National Chiao Tung University
Expert Systems with Applications | Year: 2011

The fuzzy logic constant controller (FLCC) is introduced in this paper. Unlike traditional method, a simplest controller is proposed via fuzzy logic design and Lyapunov direct method. Controllers in traditional method by Lyapunov direct method are always complicated or the functions of errors. We propose a new idea to design constant numbers as controllers, while the constant numbers are decided by the upper bound and the lower bound of the error derivatives. Via fuzzy logic rules, the strength of controllers in our new approach can be adjusted according to the error derivatives. Consequently, the slave system becomes exactly and efficiently synchronized to the trajectory of master system through FLCC. Two examples, Lorenz system and four order Chen-Lee system, are presented to illustrate the effectiveness of the new controllers in chaos generalized synchronization. © 2010 Elsevier Ltd. All rights reserved.

Hu J.-S.,National Chiao Tung University | Yang C.-H.,National Chiao Tung University
IEEE Transactions on Signal Processing | Year: 2011

In this paper, the second-order extended (SOE) H∞ filter for nonlinear discrete-time systems is derived based on an approximation to the quadratic error matrix. The solution is obtained by the game theory approach. It is shown that the result bears a strong resemblance to the SOE Kalman filter when the performance bound goes to infinity. An example of vehicle state tracking is simulated to compare the performances of the SOE Kalman filter, the first order extended and the SOE H∞ filter. Noises with unknown bias are injected into both process dynamics and measurements. The results show that the SOE H∞ filter has the smallest state tracking error. © 2011 IEEE.

Wang L.-C.,National Chiao Tung University | Yeh C.-J.,National Chiao Tung University
IEEE Journal on Selected Areas in Communications | Year: 2011

In this paper, we present a 3-cell network multipleinput multiple-output (MIMO) architecture with fractional frequency frequency (FFR) and a novel tri-sector frequency partition scheme. One fundamental question to apply the network MIMO technique in such a high interference environment is: how many base stations should be coordinated together to provide sufficient performance? We will demonstrate that the FFR-based 3-cell network MIMO architecture with the proposed tri-sector frequency partition can not only effectively overcome the intergroup interference, but can avoid executing the complex multibase- station joint processing for a huge number of cluster of cells at all locations. It will be shown that the proposed 3- cell network MIMO with the rearranged tri-sector frequency partition strategy can outperform the 7-cell network MIMO with omni-directional antennas. Various sector antenna architectures and the method for determining the inner region of the FFR cell planning are also discussed and analyzed on top of the network MIMO system. We hope that this study can provide important insights into the design of the network MIMO systems from the perspectives of architecture and deployment. © 2011 IEEE.

Su M.-S.,National Chiao Tung University | Kuo C.-Y.,National Chiao Tung University | Yuan M.-C.,National Chiao Tung University | Jeng U.-S.,National Synchrotron Radiation Research Center | And 2 more authors.
Advanced Materials | Year: 2011

The power conversion efficiency of a device incorporating a crystalline polymer/fullerene thin film improves from 5% to 7.3% - a relative increase of 45% - when an additive, diiodohexane (DIH), is present during processing. The DIH-processed active layer exhibits substantially enhanced polymer crystallinity and smaller fractal-like fullerene clusters. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zan H.-W.,National Chiao Tung University | Hsu T.-Y.,National Chiao Tung University
IEEE Electron Device Letters | Year: 2011

The influences of encapsulation on the hysteresis and the gate-bias-stress effects (both positive and negative gate bias stresses) of pentacene organic thin-film transistors (OTFTs) with poly(4-vinylphenol) and poly(4-vinylphenol- co-methyl methacrylate) (PVP-PMMA) gate dielectrics are investigated. The encapsulation and the use of less polar gate dielectrics like PVP-PMMA copolymers are both important to suppress moisture adsorption and to obtain a stable pentacene OTFT. Compared to the air-stable OTFT with a fluoropolymer dielectric, the stable encapsulated OTFT with a PVP-PMMA dielectric is a low-cost promising candidate for mass production consideration. © 2011 IEEE.

Chen C.-H.,National Chiao Tung University
2012 21st Annual Wireless and Optical Communications Conference, WOCC 2012 | Year: 2012

A compact waveguide crossing constructed by three cascaded multimode tapers on each branch is numerically analyzed by finite difference time domain method, which possesses the size of 3920 nmx3920 nm, the insertion loss of 0.187 dB and the crosstalk of -47.58 dB at the wavelength of 1550 nm and broad transmission spectrum ranging from 1500 to 1600 nm. © 2012 IEEE.

Wu C.-H.,National Chiao Tung University | Tseng Y.-C.,National Chiao Tung University
IEEE Transactions on Mobile Computing | Year: 2011

We consider a body-area sensor network (BSN) consisting of multiple small, wearable sensor nodes deployed on a human body to track body motions. Concerning that human bodies are relatively small and wireless packets are subject to more serious contention and collision, this paper addresses the data compression problem in a BSN. We observe that, when body parts move, although sensor nodes in vicinity may compete strongly with each other, the transmitted data usually exist some levels of redundancy and even strong temporal and spatial correlations. Unlike traditional data compression approaches for large-scale and multihop sensor networks, our scheme is specifically designed for BSNs, where nodes are likely fully connected and overhearing among sensor nodes is possible. In our scheme, an offline phase is conducted in advance to learn the temporal and spatial correlations of sensing data. Then, a partial ordering of sensor nodes is determined to represent their transmission priorities so as to facilitate data compression during the online phase. We present algorithms to determine such partial ordering and discuss the design of the underlying MAC protocol to support our compression model. An experimental case study in Pilates exercises for patient rehabilitation is reported. The results show that our schemes reduce more than 70 percent of overall transmitted data compared with previous approaches. © 2011 IEEE.

Chen C.-L.,National Chiao Tung University | Stark W.E.,University of Michigan | Chen S.-G.,National Chiao Tung University
IEEE Journal on Selected Areas in Communications | Year: 2011

This paper considers a MIMO multi-hop network and analyzes the relationship between its energy consumption and bandwidth efficiency. Its minimum energy consumption is formulated as an optimization problem. By taking both transmit antennas (TAs) and receive antennas (RAs) into consideration, the energy-bandwidth efficiency tradeoff in the networks is investigated. Moreover, the minimum energy of an equally-spaced relaying strategy is investigated for various numbers of antennas. In addition, the minimum energy over all possible antenna pairs is derived. Finally, the effect of the number of hops on the energy-bandwidth efficiency tradeoff is considered. For a fixed antenna pair, the minimum energy over all possible rates and hop numbers are obtained. Generally, the routes with more hops minimize the energy consumption in the low effective rate region. On the other hand, in the high effective rate region, the routes with fewer hops minimize the energy consumption. © 2006 IEEE.

Tseng F.-S.,National Chiao Tung University | Wu W.-R.,National Chiao Tung University
IEEE Transactions on Vehicular Technology | Year: 2011

Various linear transceiver design methods have been developed in three-node amplify-and-forward (AF) multiple-inputmultiple-output (MIMO) relay systems. Nonlinear designs in such systems, however, have yet to be investigated. In this paper, we propose nonlinear transceiver designs for a linear source and relay precoded system with the QR successive-interference-cancellation (SIC) receiver and another linear source and relay precoded system with the minimum-mean-squared-error (MMSE) SIC receiver. Our designs minimize the criterion of the block error rate, which is a complicated function of the source and relay precoders. Solving the two precoders simultaneously is not feasible. To overcome the difficulties, we first resort to the primal decomposition approach, i.e., transferring the original optimization to a subproblem and a master problem and solving the two precoders individually. However, since two power constraints are mutually coupled, the decomposition cannot actually be conducted. We then propose a unitary structure for the source precoder and show that the power constraints can be decoupled. As a result, the source precoder can be solved as a function of the relay precoder in the subproblem. With a proposed relay precoder structure, the master problem can further be transferred to a scalar-valued concave optimization problem. A closed-form solution can finally be derived by the KaruchKuhnTucker (KKT) conditions. Simulations show that the proposed transceivers can significantly outperform the existing linear transceivers. © 2006 IEEE.

Hsieh H.-T.,National Chiao Tung University | Wu W.R.,National Chiao Tung University
IEEE Transactions on Vehicular Technology | Year: 2011

Blind maximum-likelihood (ML) carrier-frequency-offset (CFO) estimation is considered to be difficult in interleaved orthogonal frequency-division multiple-access (OFDMA) uplink systems. This is because multiple CFOs have to be simultaneously estimated (each corresponding to a user's carrier), and an exhaustive multidimensional search is required. The computational complexity of the search may be prohibitively high. Methods such as the multiple signal classification and the estimation of signal parameters via the rotational invariance technique have been proposed as alternatives. However, these methods cannot maximize the likelihood function, and the performance is not optimal. In this paper, we propose a new method to solve the problem. With our formulation, the likelihood function can be maximized, and the optimum solution can be obtained by solving a polynomial function. Compared with the exhausted search, the computational complexity can be reduced dramatically. Simulations show that the performance of the proposed method can approach that of the Cramér-Rao lower bound. © 2010 IEEE.

Zan H.-W.,National Chiao Tung University | Tsai W.-W.,National Chiao Tung University | Chen C.-H.,National Chiao Tung University | Tsai C.-C.,National Chiao Tung University
Advanced Materials | Year: 2011

Applying nanometer dot-like doping to the channel region causes the intrinsic and effective mobilities of amorphous indium gallium zinc oxide (a-IGZO) thin-film transistor to increase. The nanodot doping reduces the effective channel length and lowers the energy barrier to facilitate electron transport in the a-IGZO film. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cheng C.-H.,National Tsing Hua University | Yeh F.-S.,National Tsing Hua University | Chin A.,National Chiao Tung University
Advanced Materials | Year: 2011

Very high performance Ni/GeOx/HfON/TaN non-volatile resistive memory is fabricated using the covalently bonded dielectric GeOx and metal oxynitride HfON as well as low cost electrodes. The device shows low set and reset powers, good 85 °C retention, and 105 endurance, which are near to the characteristics of existing commercial flash memory. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lee C.-M.,National Chiao Tung University | Tsui B.-Y.,National Chiao Tung University
IEEE Electron Device Letters | Year: 2011

High-performance polycrystalline-silicon (poly-Si) nanowire (NW) thin-film transistors (TFTs) using hafnium dioxide HfO2 as gate dielectric is successfully fabricated for the first time. The excellent short-channel characteristics are attributed to the high- κ gate dielectric, ultrathin poly-Si NW channel thickness, and omega-shaped gate structure. The record high driving capability of 549 μAm results from the ultrashort gate length LG, thin equivalent oxide thickness, and Ni silicide metal source/drain. This letter reveals the opportunity of high-performance poly-Si TFT circuits for system-on-panel and 3-D integrated circuit (3-D IC) applications. © 2006 IEEE.

Wang T.,National Chiao Tung University
IEEE Transactions on Fuzzy Systems | Year: 2011

This paper presents the algorithms and experimental results for template-based shell clustering when the datasets are represented by line segments. Compared with point datasets, such representations have several advantages, which include better scalability and noise immunity, as well as the availability of orientation information. Using both synthetic and real-world image datasets, we have experimentally demonstrated that line-segment-based representations result in both better accuracy and better efficiency in shell clustering. © 2011 IEEE.

Lu T.-C.,National Chiao Tung University | Tsai J.-L.,National Chiao Tung University
Composites Part B: Engineering | Year: 2013

Load transfer efficiency from matrix to carbon nanotubes (CNTs) plays an important role in the mechanical response of CNTs nanocomposites as it may affect the effectiveness of the nano-reinforcements. For double-walled carbon nanotubes (DWCNTs), the outer graphene layer as well as the inner layer may be responsible for the load bearing capacity. In this study, the load transfer efficiency within DWCNTs was investigated using a multiscale simulation scheme. The multiscale simulation consists of two steps. First, the atomistic behaviors between the adjacent graphite layers in DWCNTs were characterized using molecular dynamic (MD) simulation, from which a cylindrical equivalent continuum solid of DWCNTs with embedded spring elements was proposed to describe the interactions of neighboring graphene layers. Two kinds of interatomistic properties in DWCNTs, i.e., van der Walls (vdW) interactions and artificial build-up covalent bonds, were considered in the equivalent solid. Subsequently, the equivalent solid was implemented as reinforcement in the micromechanical model of CNTs nanocomposites for evaluating the load transfer efficiency. Results indicated that the DWCNTs with covalent bonds exhibit superior load transfer efficiency than those with only vdW interactions. In addition, when the DWCNTs get long, the load transfer efficiency of DWCNTs increases accordingly. © 2012 Published by Elsevier Ltd.

Huang Y.-C.,National Chiao Tung University | Ker M.-D.,National Chiao Tung University
IEEE Electron Device Letters | Year: 2013

Based on good electrostatic discharge (ESD) robustness, silicon-controlled rectifier (SCR) device is used for on-chip ESD protection. The major concern of SCR is the latch-up issue, because of its low holding voltage. Previous papers tried to design latchup-immune SCR devices; however, those devices would cause lower ESD robustness. In this letter, a new latchup-immune and robust SCR device for ESD protection is proposed and verified in a 0.25-μ m 5-V CMOS process. Through inserting one additional parasitic bipolar junction transistor into SCR device structure, this new proposed SCR can increase the holding voltage without causing degradation on its ESD robustness. © 1980-2012 IEEE.

Li W.-M.,National Chiao Tung University | Chen S.-Y.,National Chiao Tung University | Liu D.-M.,National Chiao Tung University
Acta Biomaterialia | Year: 2013

An amphiphilic gelatin-iron oxide core/calcium phosphate shell (AGIO@CaP-DOX) nanoparticle was successfully synthesized as an efficient anti-cancer drug delivery system, where doxorubicin (DOX) as a model molecule was encapsulated by electrolytic co-deposition during CaP shell formation. The shell of CaP precipitate played a pivotal role, not only in acting as a drug depot, but also in rendering the drug release rate in a highly pH-dependent controlled manner. Together with MR imaging, highly biocompatible drug-carrying CaP shell and efficient cellular internalization, the AGIO@CaP-DOX nanoparticles developed in this study area promising multifunctional nanodevice for nanotherapeutic approaches. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Hung J.-C.,National Chin - Yi University of Technology | Lin C.-C.,National Chiao Tung University
Materials and Design | Year: 2013

Numerous studies have shown the benefit of ultrasonic-vibration assisted metal forming. This benefit include a reduction in forming forces, which might be attributed to the superposition of stress, increased temperatures, the effects of interface friction, and energy absorption of dislocation. This study conducts a series of experiments and analyses to investigate the main mechanisms of a reduction in forming forces during ultrasonic-vibration assisted A6061-T6 aluminum alloy upsetting.The findings of this research confirm that, under frictionless conditions, ultrasonic vibration still reduced forming forces, and ultrasonic vibration can increase the temperature of specimens and soften specimen surface during upsetting. From metallographic analyses and micro-hardness tests, the results reveal that energy absorption of dislocation was occurred during upsetting, which also contribute to the reduction of forming force.This research concludes that the mechanisms of increased temperatures and energy absorption of dislocation can affect the material property and make a reduction in forming forces; however, the interface friction effect has nothing to do with a reduction in forming forces. © 2012.

Jheng J.-F.,National Chiao Tung University | Lai Y.-Y.,National Chiao Tung University | Wu J.-S.,National Chiao Tung University | Chao Y.-H.,National Chiao Tung University | And 2 more authors.
Advanced Materials | Year: 2013

A high organic field-effect transistor mobility (0.29 cm2V -1s-1) and bulk-heterojunction polymer solar cell performance (PCE of 6.82%) have been achieved in a low bandgap alternating copolymer consisting of axisymmetrical structural units, 5,6-difluorobenzo-2,1, 3-thiadiazole. Introducing the fluorine substituents enhanced intermolecular interaction and improved the solid-state order, which consequently resulted in the highest device performances among the 2,1,3-thiadiazole-quarterthiophene based alternating copolymers. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hsu H.-H.,National Chiao Tung University | Chang C.-Y.,National Chiao Tung University | Cheng C.-H.,National Taiwan Normal University
IEEE Electron Device Letters | Year: 2013

This letter demonstrates the feasibility of full room temperature InGaZnO thin-film transistor (TFT) using trilayer gate dielectric on flexible substrate. Through integrating high-κ SiO2/TiO2/SiO 2 (STS) gate-stack as well as InGaZnO channel thickness modulation, the resulting flexible indium-gallium-zinc oxide (IGZO)/STS TFTs show low threshold voltage of 0.5 V, small subthreshold swing of 0.129 V/decade, high field effect mobility of 76 cm2/Vs, and good ION/I OFF ratio of 6.7× 105, which have the potential for the application of high-resolution flexible display. © 1980-2012 IEEE.

Wong K.I.,National Chiao Tung University
International Journal of Sustainable Transportation | Year: 2013

Reducing automobile dependency is one of the key challenges in the development of a sustainable transportation system. However, to evaluate the effectiveness of a policy, it is necessary to understand the factors that would influence the choice behavior of travelers. In this paper, the impacts of urban characteristics to the household vehicle ownership level for cars and motorcycles in Macao are investigated. A discrete choice approach is used to estimate the number of vehicles that a household would own using disaggregate household survey data. The result reveals that whereas income has positive effect on both car and motorcycle ownerships, the demographic attributes of the residential locations have different effects to the ownerships of the two vehicle types. We also propose that the motorcycle ownership should be represented at a personal decision level instead of a household level. © 2013 Copyright Taylor and Francis Group, LLC.

Wang C.-H.,National Chiao Tung University | Chen J.-N.,National Chiao Tung University
Computers and Industrial Engineering | Year: 2012

In response to fast-growing and rapidly-changing markets, launching new products faster than competitors cannot only assist firms in acquiring larger market share but also reducing development lead time, significantly. However, owing to its intrinsically uncertain properties of managing NPD (new product development), manufacturing companies often struggle with the dilemma of increasing product variety or controlling manufacturing complexity. In this study, a fuzzy MCDM (multi-criteria decision making) based QFD (quality function deployment) which integrates fuzzy Delphi, fuzzy DEMATEL (decision making trial and evaluation laboratory), with LIP (linear integer programming) is proposed to assist an enterprise in fulfilling collaborative product design and optimal selection of module mix when aiming at multi-segments. In particular, Fuzzy Delphi is adopted to gather marketing information from invited customers and their assessments of marketing requirements are pooled to reach a consensus; fuzzy DEMATEL is utilized to derive the priorities of technical attributes in a market-oriented manner; and LIP is used to maximize product capability with consideration of supplier's budget constraints of manufacturing resources. Furthermore, a real case study on developing various types of sport and water digital cameras is demonstrated to validate the proposed approach. © 2012 Elsevier Ltd. All rights reserved.

Chen L.J.,National Tsing Hua University | Wu W.W.,National Chiao Tung University
Materials Science and Engineering R: Reports | Year: 2010

In situ investigation of the temperature induced phase transformation, structural and chemical evolution of nanocrystals is important for understanding the structure and stability of nanomaterials. Transmission electron microscopy (TEM), one of the most powerful tools for characterizing nanostructured materials, is essential for the development of nanotechnology. In situ TEM is a technique that allows a direct observation of dynamic properties in nanoscale. Recent development of ultra-high vacuum TEM (UHV-TEM) further enables the investigation on atomic-scale materials systems in a clean environment. The appropriate utilization of the UHV-TEM will be beneficial in studying the fundamental mechanisms of dynamic reactions, formation of transient phase, solid-state amorphization, epitaxial growth, growth kinetics and evolution of defects. In this paper, we present the most recent progress in observing dynamic processes in nanoscale by in situ UHV-TEM. © 2010 Elsevier B.V. All rights reserved.

Li L.-L.,National Chiao Tung University | Diau E.W.-G.,National Chiao Tung University
Chemical Society Reviews | Year: 2013

Nature has chosen chlorophylls in plants as antennae to harvest light for the conversion of solar energy in complicated photosynthetic processes. Inspired by natural photosynthesis, scientists utilized artificial chlorophylls - the porphyrins - as efficient centres to harvest light for solar cells sensitized with a porphyrin (PSSC). After the first example appeared in 1993 of a porphyrin of type copper chlorophyll as a photosensitizer for PSSC that achieved a power conversion efficiency of 2.6%, no significant advance of PSSC was reported until 2005; beta-linked zinc porphyrins were then reported to show promising device performances with a benchmark efficiency of 7.1% reported in 2007. Meso-linked zinc porphyrin sensitizers in the first series with a push-pull framework appeared in 2009; the best cell performed comparably to that of a N3-based device, and a benchmark 11% was reported for a porphyrin sensitizer of this type in 2010. With a structural design involving long alkoxyl chains to envelop the porphyrin core to suppress the dye aggregation for a push-pull zinc porphyrin, the PSSC achieved a record 12.3% in 2011 with co-sensitization of an organic dye and a cobalt-based electrolyte. The best PSSC system exhibited a panchromatic feature for light harvesting covering the visible spectral region to 700 nm, giving opportunities to many other porphyrins, such as fused and dimeric porphyrins, with near-infrared absorption spectral features, together with the approach of molecular co-sensitization, to enhance the device performance of PSSC. According to this historical trend for the development of prospective porphyrin sensitizers used in PSSC, we review systematically the progress of porphyrins of varied kinds, and their derivatives, applied in PSSC with a focus on reports during 2007-2012 from the point of view of molecular design correlated with photovoltaic performance.

Huang C.-H.,National Chiao Tung University | Liu W.-R.,Material and Chemical Research Laboratories | Chen T.-M.,National Chiao Tung University
Journal of Physical Chemistry C | Year: 2010

Single-phased white-light-emitting phosphors Ca9Gd(PO 4)7:Eu2+, Mn2+ were synthesized by solid state reactions. Tuning the Eu2+/Mn2+ ratio via the energy transfer varied the emission hue of Ca9Gd(PO4) 7:0.007Eu2+, Mn2+ from blue-greenish (0.219, 0.371) to white-light (0.326, 0.328) and eventually to red (0.625, 0.307). The mechanism of transferring energy from a sensitizer Eu2+ to an activator Mn2+ in Ca9Gd(PO4) 7:Eu2+, Mn2+ phosphors was demonstrated to be an electric dipole-quadrupole interaction. Combining a near-UV 380 nm chip and a white-emitting Ca9Gd(PO4)7:0.007Eu 2+, 0.02 Mn2+ phosphor produced a white-light near-UV LED, demonstrating CIE chromaticity coordinates of (0.312, 0.327) and a color temperature of 6569 K. © 2010 American Chemical Society.

Cheng H.-M.,National Chiao Tung University | Hsieh W.-F.,National Chiao Tung University
Energy and Environmental Science | Year: 2010

Self-assembled ZnO secondary nanoparticles have been fabricated as an effective photoelectrode for dye-sensitized solar cells (DSCs). The hierarchical architecture, which manifested the significant light-scattering, can provide more photon harvesting. In addition, dye-molecule adsorption was sufficient due to enough internal surface area provided by the primary single nanocrystallites. Two indoline dyes, coded D149 and D205, were used as the sensitizers of ZnO DSCs with the optimal energy conversion efficiencies of 4.95% and 5.34%, respectively, under AM 1.5 full sunlight illumination (100 mW cm-2). The enhancement of the open-circuit photovoltage (Voc) and the short-circuit photocurrent density (Jsc) for D205-sensitized ZnO DSCs was ascribed to the effective suppression of electron recombination by extending the alkyl chain on the terminal rhodanine moiety from ethyl to octyl. Further evidence is obtained from the electrochemical impedance spectroscopy (EIS) which exhibits a longer electron lifetime for D205-sensitized ZnO DSC in comparison with the D149-sensitized one. © 2010 The Royal Society of Chemistry.

Chen J.Y.,National Chiao Tung University | Sun K.W.,National Chiao Tung University
Solar Energy Materials and Solar Cells | Year: 2010

In this work we investigated the effects of growth time, spin-coating rates, and solution concentration on the reflection properties of the solution-grown ZnO nanorod arrays. The vertically aligned nanorod arrays were deposited on the surface of the Si solar cells as the antireflection (AR) layer. We found that the nanorod morphology, controlled through synthetic chemistry, has a great effect on the AR layer performance. We also demonstrated that the light harvest efficiency of the solar cells was greatly improved from 10.4% to 12.8% by using the vertically aligned ZnO nanorod arrays as the AR layer on poly-Si solar cells. © 2010 Elsevier B.V. All rights reserved.

Chen J.Y.,National Chiao Tung University | Sun K.W.,National Chiao Tung University
Solar Energy Materials and Solar Cells | Year: 2010

In this report, the results of the fabrication of nanostructured Si molds by e-beam lithography and chemical wet etching are presented. A home-made pneumatic nanoimprint system was used to transfer the mold patterns to a PMMA layer on a Si template using the spin-coating replication/hot-embossing techniques. The patterned PMMA layer was peeled off from the Si template and directly transferred onto the surface of a poly-Si P-N junction solar cell device to serve as the anti-reflection (AR) layer. It provides a simple and low-cost means for large-scale use in the production of AR layers for improving solar cell performance. A drastic reduction in reflectivity of the AR layer over a broad spectral range was demonstrated. In addition, the great improvement on the light harvest efficiency of the solar cells from 10.4% to 13.5% using the nanostructured PMMA layer as the AR layer was validated. © 2009 Elsevier B.V. All rights reserved.

Chiang Y.-J.,National Chiao Tung University | Pan F.-M.,National Chiao Tung University
Journal of Physical Chemistry C | Year: 2013

We prepared PdO nanoflake thin films by reactive sputter deposition and studied their gas-sensing response to CO at temperatures below 250 C. The PdO thin film, which has a large open surface area allowing for rapid and extensive CO adsorption, exhibits a complicated CO sensing behavior. At temperatures below 150 C, the electrical conductance of the thin film drops upon the exposure of the CO/dry air gas mixture. The CO sensing mechanism in this temperature range is described by the oxygen ionosorption model. At 150 C, oscillatory response occurs when the CO concentration is larger than 2000 ppm. The oscillatory response is due to the reactivity switching between the PdO reduction and reoxidation reactions. In addition, the PdO thin film shows a rapid increase in the conductance before and after the oscillatory response regime. The conductance increase is ascribed to the positive charge accumulation at the interface between the PdO thin film and metal Pd nanoislands, which are formed during the PdO reduction. At temperatures higher than 150 C, the conductance drops when the PdO thin film is exposed to CO. Besides the ionosorption model, the oxygen vacancy model is used to account for the CO sensing response of the thin film in the high-temperature range. On the basis of the inverse change in the CO sensing sensitivity at 150 C, a CO sensor of high selectivity, which integrates two PdO sensing elements operating independently at 150 C and a lower temperature, is proposed. © 2013 American Chemical Society.

Huang H.L.,National Chiao Tung University
BMC bioinformatics | Year: 2012

Existing methods for predicting protein solubility on overexpression in Escherichia coli advance performance by using ensemble classifiers such as two-stage support vector machine (SVM) based classifiers and a number of feature types such as physicochemical properties, amino acid and dipeptide composition, accompanied with feature selection. It is desirable to develop a simple and easily interpretable method for predicting protein solubility, compared to existing complex SVM-based methods. This study proposes a novel scoring card method (SCM) by using dipeptide composition only to estimate solubility scores of sequences for predicting protein solubility. SCM calculates the propensities of 400 individual dipeptides to be soluble using statistic discrimination between soluble and insoluble proteins of a training data set. Consequently, the propensity scores of all dipeptides are further optimized using an intelligent genetic algorithm. The solubility score of a sequence is determined by the weighted sum of all propensity scores and dipeptide composition. To evaluate SCM by performance comparisons, four data sets with different sizes and variation degrees of experimental conditions were used. The results show that the simple method SCM with interpretable propensities of dipeptides has promising performance, compared with existing SVM-based ensemble methods with a number of feature types. Furthermore, the propensities of dipeptides and solubility scores of sequences can provide insights to protein solubility. For example, the analysis of dipeptide scores shows high propensity of α-helix structure and thermophilic proteins to be soluble. The propensities of individual dipeptides to be soluble are varied for proteins under altered experimental conditions. For accurately predicting protein solubility using SCM, it is better to customize the score card of dipeptide propensities by using a training data set under the same specified experimental conditions. The proposed method SCM with solubility scores and dipeptide propensities can be easily applied to the protein function prediction problems that dipeptide composition features play an important role. The used datasets, source codes of SCM, and supplementary files are available at http://iclab.life.nctu.edu.tw/SCM/.

Ramakrishnam Raju M.V.,National Chiao Tung University | Lin H.-C.,National Chiao Tung University
Organic Letters | Year: 2014

A novel [2]catenane 2-C based on the tetraphenylethene (TPE) and orthogonal H-bonded cleft was successfully constructed. VT-NMR and TEM measurements demonstrate that 2-C could be self-assembled to induce an enabled aggregation-induced emission (AIE) in aqueous solution and solid state owing to its TPE unit as well as present unique acid-base controllable and reversible supramolecular self-assembled nanosuperstructures by interplay of a wide range of noncovalent interactions. © 2014 American Chemical Society.

Chow C.W.,National Chiao Tung University | Yeh C.H.,Industrial Technology Research Institute of Taiwan
Optics Express | Year: 2010

As different high speed signal-remodulation wavelength division multiplexed - passive optical network (WDM-PON) solutions up to 10 Gb/s have been proposed, researchers are going to further increase the data rate of PON towards 40 Gb/s or higher. However, scaling up from 10 Gb/s/wavelength to 40 Gb/s/wavelength PON is very challenging. Although many studies have been performed on upgrading the exiting 10 Gb/s network to 40 Gb/s, the study of the 40 Gb/s signal-remodulation network is very little. In this work, we will first study the chromatic dispersion effect on the signal-remodulation PON. Then, we will propose and demonstrate a signal-remodulation PON using 40-Gb/s downstream differential-phase shift keying (DPSK) and 40-Gb/s upstream on-off keying (OOK) signals. By using the reduced modulation index (RMI) of the downstream DPSK signal, the tolerance to the residual chromatic dispersion of the whole system can be greatly enhanced. Due to the reduced impact of the accumulated chromatic dispersion, the quality of the upstream remodulated OOK signal can be significantly improved. Besides, by detecting the downstream demodulated DPSK signal at the destructive output port of the demodulator, good quality of the demodulated DPSK signal can still be achieved. © 2010 Optical Society of America.

Kandiah M.,National Chiao Tung University | Urban P.L.,National Chiao Tung University
Chemical Society Reviews | Year: 2013

Ultrasensitive mass spectrometric analysis of organic molecules is important for various branches of chemistry, and other fields including physics, earth and environmental sciences, archaeology, biomedicine, and materials science. It finds applications-as an enabling tool-in systems biology, biological imaging, clinical analysis, and forensics. Although there are a number of technical obstacles associated with the analysis of samples by mass spectrometry at ultratrace level (for example analyte losses during sample preparation, insufficient sensitivity, ion suppression), several noteworthy developments have been made over the years. They include: sensitive ion sources, loss-free interfaces, ion optics components, efficient mass analyzers and detectors, as well as "smart" sample preparation strategies. Some of the mass spectrometric methods published to date can achieve sensitivity which is by several orders of magnitude higher than that of alternative approaches. Femto- and attomole level limits of detection are nowadays common, while zepto- and yoctomole level limits of detection have also been reported. We envision that the ultrasensitive mass spectrometric assays will soon contribute to new discoveries in bioscience and other areas. © 2013 The Royal Society of Chemistry.

Chuang C.-C.,National Chiao Tung University | Sun C.-W.,National Chiao Tung University
Biomedical Optics Express | Year: 2014

The prefrontal cortex (PFC) is thought to play an important role in "higher" brain functions such as personality and emotion that may associated with several gender-related mental disorders. In this study, the gender effects of functional connectivity, cortical lateralization and significantly differences in the PFC were investigated by using resting-state functional optical tomography (fOT) measurement. A total of forty subjects including twenty healthy male and twenty healthy female adults were recruited for this study. In the results, the hemoglobin responses are higher in the male group. Additionally, male group exhibited the stronger connectivity in the PFC regions. In the result of lateralization, leftward dominant was observed in the male group but bilateral dominance in the female group. Finally, the 11 channels of the inferior PFC regions (corresponding to the region of Brodmann area 45) are significant different with spectrum analysis. Our findings suggest that the resting-state fOT method can provide high potential to apply to clinical neuroscience for several gender-related mental disorders diagnosis. © 2014 Optical Society of America.

Ko C.-T.,National Chiao Tung University | Chen K.-N.,National Chiao Tung University
Microelectronics Reliability | Year: 2012

3D integration provides a promising solution to achieve system level integration with high function density, small form factor, enhanced transmission speed and low power consumption. Stacked bonding is the key technology to enable the communication between different strata of the 3D integration system. Low temperature bonding approaches are explored in industry to solve the performance degradation issue of the integrated devices. In this paper, various low temperature bonding technologies are reviewed and introduced, as well as the latest developments in world-wide companies and research institutes. The outlook for industrial application is also addressed in the paper. © 2011 Elsevier Ltd. All rights reserved.

Kuo T.-W.,National Chiao Tung University | Chen T.-M.,National Chiao Tung University
Journal of the Electrochemical Society | Year: 2010

Green-emitting phosphors of Sr3 La (PO4)3: Ce3+, Tb3+ have been synthesized by a solid-state reaction. The energy transfer from Ce3+ to Tb3+ is a resonant type via a dipole-dipole mechanism with an energy-transfer critical distance of 7.6 Å. By utilizing the principle of energy transfer and appropriate tuning of activator contents, we have also made an attempt to observe a strong green emission performance displayed by this phosphor for use as a coating material on compact fluorescent lamps (CFLs). The results clearly indicate that the luminous efficiency based on Sr3 (La0.67 Ce0.08 Tb0.25) (PO4)3 was found to be 69 lm/W. The good luminous efficiency and lumen maintenance (2000 h, 91.8%) of the green-emitting CFL demonstrate that this phosphor can be suitable for application on a short UV fluorescent lamp. Additionally, the Sr3 (La0.67 Ce0.08 Tb0.25) (PO4)3 green phosphor has advantages of environmental friendliness and low cost. © 2010 The Electrochemical Society.

Chang T.-P.,National Chiao Tung University | Hu J.-L.,National Chiao Tung University
Applied Energy | Year: 2010

This article introduces total-factor energy productivity change index (TFEPI) based on the concept of total-factor energy efficiency and the Luenberger productivity index to evaluate the energy productivity change of regions in China with a total-factor framework. Moreover, the TFEPI can be decomposed into change in energy efficiency and shift in the energy use technology. According to the computation results, China's energy productivity was decreasing by 1.4% per year during 2000-2004. The average total-factor energy efficiency improves about 0.6% per year, while total-factor energy technical change declines progressively 2% annually. The factors affecting TFEPI are also examined: (1) The east area has a higher TFEPI than the central and west area; (2) increasing the development status and electricity share of energy consumption will improve the region's TFEPI performance, while increasing the proportion of GDP generated by the secondary industry deteriorates TFEPI of a region. © 2010 Elsevier Ltd. All rights reserved.

Urban P.L.,National Chiao Tung University
New Journal of Chemistry | Year: 2014

The origin of life on Earth has been the subject of inquiry since the early days of philosophical thought. The main questions are centred around the formation of protocells capable of metabolism and replication. Research studies have been carried out to simulate the conditions on early Earth. They have led to a proposal that the first cells could have emerged through self-assembly of molecules such as phospholipids. When such structures split pre-metabolic mixtures into small-volume aliquots, biochemical reactions could be "digitised" giving rise to self-sustaining entities. Since then compartmentalisation has remained instrumental to biology and biochemistry. It prevents dispersion of metabolic intermediates, and facilitates molecular interactions by means of confinement. Eukaryotic organisms are highly compartmentalised on various levels (subcellular, cellular, and organ levels). Apart from cell-level compartmentalisation, metabolism relies on the separation of biochemical pathways into subcellular organelles. Whilst in vitro studies in chemical and synthetic biology generally use homogeneous mixtures of reactants and biocatalysts, a faithful mimicry of biochemical systems requires introduction of metabolic compartments. In fact, the compartmentalised structure of biological tissues can serve as a blueprint in applied research (e.g. biochemical engineering). Three-dimensional arrays of interconnected microdroplet compartments can already be engineered. It is envisioned that compartmentalisation will play a key role in emerging biotechnologies, including those related to in vitro growth of tissues and organs, offering new possibilities in regenerative medicine, as well as the construction of intelligent and miniaturised systems for multi-step biosyntheses and biocomputing. This journal is © the Partner Organisations 2014.

Chen Y.F.,National Chiao Tung University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

The geometry of classical dynamics in coupled oscillators with SU(2) transformations is explored and found to be relevant to a family of continuous-transformation orbits between Lissajous and trochoidal curves. The quantum wave-packet coherent states are derived analytically to correspond exactly to the transformation geometry of classical dynamics. By using the quantum wave-packet coherent states derived herein, stationary coherent states are constructed and are shown to possess spatial patterns identical to the transformation geometry between Lissajous and trochoidal orbits. © 2011 American Physical Society.

Lu T.-W.,National Chiao Tung University | Lee P.-T.,National Chiao Tung University
Optics Letters | Year: 2013

We propose a photonic crystal (PhC) nanofishbone (NFB) nanocavity, which confines an ultrahigh Q (∼1.8 × 107) transverse-magnetic (TM) mode. With thin slab thickness and only few PhC periods, the TM mode in NFB nanocavity shows higher Q, larger confinement factor and smaller mode volume than that in PhC nanobeam nanocavity while the total etched-surface area is also significantly reduced. This PhC NFB nanocavity with very compact device size will be very beneficial for quantum cascade lasers, plasmonic nanolasers, and other applications needing high Q TM modes. © 2013 Optical Society of America.

Herein we demonstrate a tricyclohexylphosphine-catalyzed cycloaddition of (E)- or (Z)-alkyl 5-substituted phenylpent-2-en-4-ynoates with [60]fullerene to give cyclopentenofullerenes in good to excellent yields, through initial chemo- and regioselective 1,4-addition of phosphines at the b-carbon of the enyne substrates. The nucleophilic addition pattern of P (cHx)3 is found to be different from that of Gilman or Grignard reagents toward the studied enynes. The resulting cyclopentenofullerenes, characterized with spectrometric methods and single crystal X-ray diffraction analysis, exhibit comparable or higher LUMO energy levels than a typical n-type material, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). © 2013 Wiley-VCH Verlag GmbH&Co. KGaA, Weinheim.

Wu P.-C.,National Chiao Tung University | Lisetski L.N.,Ukrainian Academy of Sciences | Lee W.,National Chiao Tung University
Optics Express | Year: 2015

We focus on investigating the dielectric behaviors and the lowfrequency texture transitions in a cholesteric liquid crystal (CLC) doped with graphene nanoplatelets (GNPs) by means of dielectric spectroscopy and measurements of electro-optical responses. The experimental results indicate that incorporating GNPs at a content of 0.5 wt% into the CLC leads to significant suppression of ionic behaviors, as manifested by the reduction in ionic density, diffusivity, and relaxation frequency. In addition, the electro-optical properties of the GNP-doped CLC cell show the lowered operation voltage for the switching from the planar to focal conic state and the absence of the low-frequency focal-conic-to-uniform-lying-helix texture transition. Such results are attributable to the effects of GNPs as nuclei in the CLC medium, giving rise to the repression of the ionic and electrohydrodynamic effects. © 2015 Optical Society of America.

Yeh C.H.,Industrial Technology Research Institute of Taiwan | Chow C.W.,National Chiao Tung University
Laser Physics Letters | Year: 2010

In this paper, a broadband wavelength-tunable erbiumdoped fiber (EDF) ring laser with single longitudinal mode (SLM) output achieving 82.6 nm lasing bandwidth from 1481.0 to 1563.6 nm is proposed and experimentally demonstrated. For the proposed laser scheme, the S- and C-band erbium-doped fiber amplifiers (EDFAs) in parallel structure are used to serve as the gain medium for broadband wavelength tuning. Furthermore, we use a saturable-absorber filter (SAF) inside the fiber cavity to serve as a narrow band filter to guarantee a SLM operation. Besides, the performance of output power, wavelength, side-mode suppression ratio (SMSR) and stability are also analyzed and discussed. © 2010 by Astro Ltd.

Lin Y.-M.,Industrial Technology Research Institute of Taiwan | Tien P.-L.,National Chiao Tung University
IEEE Journal on Selected Areas in Communications | Year: 2010

In this paper, we propose a novel architecture for next-generation orthogonal frequency division multiple access (OFDMA)-based passive optical networks (PON's), referred to as ROFPON. Besides carrying local broadband OFDMA data, ROFPON seamlessly supports radio-over-fiber (RoF) transports between the central office and multiple remote antennas at end users without using costly WDM lasers. We analytically and experimentally study the receiver sensitivity to OFDMA signals and the radio frequency (RF) signal's performance. By corroborating simulation results with experimental results, we discuss the determination of crucial system parameters, such as the optimal broadband-to-radio power ratio, and the exploitation of a notch filter for removing RF interference. Experimental results show that the integrated 10 Gb/s OFDMA and three 20 MHz RF signals are successfully transported both downstream and upstream over a 20 km single-mode-fiber PON. Finally, experimental results demonstrate that QPSK-encoded WiMAXformat RF signals are transmitted/relayed upstream with E-O-E conversion at each optical network unit (ONU), and received error-free at the optical line terminal after cascading 32 ONU's. © 2010 IEEE.

Sun C.-C.,National Chiao Tung University
Expert Systems with Applications | Year: 2010

Multiple criteria decision-making (MCDM) research has developed rapidly and has become a main area of research for dealing with complex decision problems. The purpose of the paper is to explore the performance evaluation model. This paper develops an evaluation model based on the fuzzy analytic hierarchy process and the technique for order performance by similarity to ideal solution, fuzzy TOPSIS, to help the industrial practitioners for the performance evaluation in a fuzzy environment where the vagueness and subjectivity are handled with linguistic values parameterized by triangular fuzzy numbers. The proposed method enables decision analysts to better understand the complete evaluation process and provide a more accurate, effective, and systematic decision support tool. © 2010 Elsevier Ltd. All rights reserved.

Hsiao C.-W.,Alpha Image Technology Corporation | Tsai W.-J.,National Chiao Tung University
IEEE Transactions on Circuits and Systems for Video Technology | Year: 2010

Multiple description (MD) video coding is one of the approaches that can be used to reduce the detrimental effects caused by transmission over error-prone networks. A number of approaches have been proposed for MD coding, where each provides a different tradeoff between compression efficiency and error resilience. This paper first presents two basic MD coding methods; one segments the video in the spatial domain, while the other in the frequency domain. Then a hybrid MD coding method is proposed. The hybrid MD encoder segments the video in both the spatial and frequency domains. In the case of data loss, the hybrid MD decoder takes advantage of the residual-pixel correlations in the spatial domain, and the coefficient correlations in the frequency domain, for error concealment. As a result, better error resilience can be achieved at high compression efficiency. The advantages of the proposed hybrid MD method are demonstrated in the contexts of descriptor loss in ideal channels and in packet-loss networks. © 2010 IEEE.

Kuo H.-Y.,National Chiao Tung University
International Journal of Engineering Science | Year: 2010

We propose a theoretical framework for evaluation of electrostatic potentials in an unbounded isotropic matrix containing a number of arbitrarily dispersed elliptic cylinders subjected to a remotely prescribed potential field. The inclusions could be homogeneous or confocally multicoated, and may have different sizes, aspect ratios and different conductivities. The approach is based on a multipole expansion formalism, together with a construction of consistency conditions and translation operators. This procedure generalizes the approach of the classic work of Rayleigh [1] for a periodic array of circular disks or spheres to an arbitrarily dispersion of elliptic cylinders. We combine the methods of complex potentials with a re-expansion formulae and the generalized Rayleigh's formualtion to obtain a complete solution of the many-inclusion problem. We show that the coefficients of field expansions can be written in the form of an infinite set of linear algebraic equations. Numerical results are presented for several configuarions. We further apply the obtained field solutions to determine the effective conductivity of the composite. © 2009 Elsevier Ltd. All rights reserved.

Sha D.Y.,Chung Hua University | Lin H.-H.,National Chiao Tung University
Expert Systems with Applications | Year: 2010

Most previous research into the job-shop scheduling problem has concentrated on finding a single optimal solution (e.g., makespan), even though the actual requirement of most production systems requires multi-objective optimization. The aim of this paper is to construct a particle swarm optimization (PSO) for an elaborate multi-objective job-shop scheduling problem. The original PSO was used to solve continuous optimization problems. Due to the discrete solution spaces of scheduling optimization problems, the authors modified the particle position representation, particle movement, and particle velocity in this study. The modified PSO was used to solve various benchmark problems. Test results demonstrated that the modified PSO performed better in search quality and efficiency than traditional evolutionary heuristics. © 2009 Elsevier Ltd. All rights reserved.

Chen Y.-C.,Realtek Inc. | Su Yu.,National Chiao Tung University
IEEE Transactions on Wireless Communications | Year: 2010

This paper presents two analytic correlated multiple-input multiple-output (MIMO) block fading channel models and their time-variant extensions that encompass the popular Kronecker model and the more general Weichselberger model as special cases. Both static and time-variant models offer compact representations of spatial- and/or time-correlated channels. When the transmit antenna array is such that the associated MIMO channel has a small angle spread (AS), which occurs quite often in a cellular downlink, our models admit reduced-rank channel representations. They also provide compact channel state information (CSI) descriptions which are needed in feedback systems and in many post channel estimation applications. The latter has the important implication of reduced feedback channel bandwidth requirement and lower post-processing complexity. Based on one of the proposed channel models we present novel iterative algorithms for estimating static and time-variant MIMO channels. The proposed models make it natural to decompose each iteration of our algorithms into two successive stages that are responsible for estimating the correlation coefficients and the signal direction, respectively. Using popular industry-approved standard channel models, we verify through simulations that our algorithms yield good MSE performance which, in many practical cases, is better than that achievable by a conventional leastsquare estimator. The mean-squared error (MSE) performance of our estimators are analyzed and the resulting predictions are consistent with those estimated by simulations. © 2006 IEEE.

Peng W.-R.,National Chiao Tung University
Journal of Lightwave Technology | Year: 2010

In this paper, we characterize the impact of laser phase noise (PN) in direct-detection optical OFDM (DDO-OFDM) and identify its many differences from those in coherent optical OFDM (CO-OFDM). The analytical models for the diverse PN effects, including power degradation, phase rotation term (PRT), and inter-carrier interference (ICI), are given in terms of critical system parameters with or without the small PN assumption. In particular, the analytical upper-bound of the ICI power with a simple form is also provided. We also present a bit error rate (BER) estimation approach which is proven to be reliable for an optical signal-to-noise-ratio (OSNR) penalty lower than ∼2 dB. In addition, the PN tolerances, in terms of OSNR penalty, are also numerically analyzed and discussed with different QAM formats, data rates, laser linewdiths, and subcarrier numbers. © 2010 IEEE.

MicroRNAs (miRNAs) play a critical role in down-regulating gene expression. By coupling with Argonaute family proteins, miRNAs bind to target sites on mRNAs and employ translational repression. A large amount of miRNA-target interactions (MTIs) have been identified by the crosslinking and immunoprecipitation (CLIP) and the photoactivatable-ribonucleoside-enhanced CLIP (PAR-CLIP) along with the next-generation sequencing (NGS). PAR-CLIP shows high efficiency of RNA co-immunoprecipitation, but it also lead to T to C conversion in miRNA-RNA-protein crosslinking regions. This artificial error obviously reduces the mappability of reads. However, a specific tool to analyze CLIP and PAR-CLIP data that takes T to C conversion into account is still in need. We herein propose the first CLIP and PAR-CLIP sequencing analysis platform specifically for miRNA target analysis, namely miRTarCLIP. From scratch, it automatically removes adaptor sequences from raw reads, filters low quality reads, reverts C to T, aligns reads to 3'UTRs, scans for read clusters, identifies high confidence miRNA target sites, and provides annotations from external databases. With multi-threading techniques and our novel C to T reversion procedure, miRTarCLIP greatly reduces the running time comparing to conventional approaches. In addition, miRTarCLIP serves with a web-based interface to provide better user experiences in browsing and searching targets of interested miRNAs. To demonstrate the superior functionality of miRTarCLIP, we applied miRTarCLIP to two public available CLIP and PAR-CLIP sequencing datasets. miRTarCLIP not only shows comparable results to that of other existing tools in a much faster speed, but also reveals interesting features among these putative target sites. Specifically, we used miRTarCLIP to disclose that T to C conversion within position 1-7 and that within position 8-14 of miRNA target sites are significantly different (p value = 0.02), and even more significant when focusing on sites targeted by top 102 highly expressed miRNAs only (p value = 0.01). These results comply with previous findings and further suggest that combining miRNA expression and PAR-CLIP data can improve accuracy of the miRNA target prediction. To sum up, we devised a systematic approach for mining miRNA-target sites from CLIP-seq and PAR-CLIP sequencing data, and integrated the workflow with a graphical web-based browser, which provides a user friendly interface and detailed annotations of MTIs. We also showed through real-life examples that miRTarCLIP is a powerful tool for understanding miRNAs. Our integrated tool can be accessed online freely at http://miRTarCLIP.mbc.nctu.edu.tw.

Daraghmi E.Y.,National Chiao Tung University | Yuan S.-M.,National Chiao Tung University
Computers in Human Behavior | Year: 2014

Nowadays, the glory of social networking sites is unprecedented. Thus, we are so close; the world is even smaller than you thought; a friend of your friend probably knows a friend of others friend; Facebook shrunk the gap between us. The six degrees of separation theory proposed in 1967 stated that we are all just six degrees of separation apart. This paper addresses the research problem of identifying the degree of separation from a different viewpoint by considering not only the degree of separation between two normal-persons or famous-persons, but also between two persons with very rare-special features. We re-evaluate and extend the six degrees of separation theory by using a real social searching Facebook tool "We R So Close". Experiments were performed on Facebook platform; and the graph database was used to store the collected data. Results add a new phase to the research that cemented the phrase "six degrees of separation", it reported that the average number of acquaintances separating any two people no matter who they are even with rare-special features, i.e. those who work in rare jobs, is not six but 3.9. © 2013 Elsevier B.V. All rights reserved.

Huang C.-H.,National Chiao Tung University | Chen T.-M.,National Chiao Tung University
Inorganic Chemistry | Year: 2011

Eu 2+-activated Sr 8MgY(PO 4) 7 and Sr 8MgLa(PO 4) 7 yellow-emitting phosphors were successfully synthesized by solid-state reactions for applications in excellent color rendering index white light-emitting diodes (LEDs). The excitation and reflectance spectra of these phosphors show broad band excitation and absorption in the 250-450 nm near-ultraviolet region, which is ascribed to the 4f 7 → 4f 65d 1 transitions of Eu 2+. Therefore, these phosphors meet the application requirements for near-UV LED chips. Upon excitation at 400 nm, the Sr 8MgY(PO 4) 7:Eu 2+ and Sr 8MgLa(PO 4) 7:Eu 2+ phosphors exhibit strong yellow emissions centered at 518, 610, and 611 nm with better thermal stability than (Ba,Sr) 2SiO 4 (570 nm) commodity phosphors. The composition-optimized concentrations of Eu 2+ in Sr 8MgLa(PO 4) 7:Eu 2+ and Sr 8MgY(PO 4) 7:Eu 2+ phosphors were determined to be 0.01 and 0.03 mol, respectively. A warm white-light near-UV LED was fabricated using a near-UV 400 nm chip pumped by a phosphor blend of blue-emitting BaMgAl 10O 17:Eu 2+ and yellow-emitting Sr 8MgY(PO 4) 7:0.01Eu 2+ or Sr 8MgLa(PO 4) 7:0.03Eu 2+, driven by a 350 mA current. The Sr 8MgY(PO 4) 7:0.01Eu 2+ and Sr 8MgLa(PO 4) 7:0.03Eu 2+ containing LEDs produced a white light with Commission International de I'Eclairage (CIE) chromaticity coordinates of (0.348, 0.357) and (0.365, 0.328), warm correlated color temperatures of 4705 and 4100 K, and excellent color rendering indices of 95.375 and 91.75, respectively. © 2011 American Chemical Society.

Li S.-C.S.,National Chiao Tung University
Computers in Human Behavior | Year: 2014

Tablet PCs, netbooks, and smart phones are similar to one another in that they possess the basic functions of computers, but they differ in what functions they emphasize. Rogers' diffusion of innovation model has been widely recognized as a powerful model for predicting technology adoption. This study adopted Rogers' model to examine the adoption intentions of the three new types of computers. A telephone survey was conducted to collect data. This study made 1757 telephone calls, from which 1100 valid calls were obtained, representing a response rate of 62.61%. The data analysis demonstrates that the findings are generally congruent with the predictions of Rogers' model. However, this study's results also reveal one limitation of Rogers' model, its pro-innovation bias, which explains why the diffusion of netbooks was incongruent with Rogers' model. © 2014 Elsevier Ltd. All rights reserved.

This study employed Rogers' model to compare the diffusion of digital terrestrial television with the diffusion of digital cable in Taiwan. A telephone survey, which yielded 753 valid questionnaires, was conducted to collect data. The results of this study show that the factors affecting the intention to adopt digital terrestrial television differed widely from those affecting the intention to adopt digital cable. The diffusion of digital cable was discovered to be generally congruent with the prediction of Rogers' model, while the diffusion of digital terrestrial television was not. This second finding reveals a limitation in Rogers' model, namely, its alleged pro-innovation bias. It may be that the respondents in this study looked favorably on digital cable because they considered it, and not digital terrestrial television, to be an inevitable technology. Furthermore, this study found that awareness played an important role in respondents' adoption of digital television. This study therefore suggests that, to accelerate digital conversion, Taiwan's government should establish policies to educate people about digital television. © 2013 Elsevier Ltd. All rights reserved.

Chen C.-S.,National Chiao Tung University | Pan F.-M.,National Chiao Tung University
Journal of Power Sources | Year: 2012

We prepared PdO nanoflake thin films on carbon cloths by reactive sputtering deposition, and studied electrocatalytic performance of Pt nanoparticles electrodeposited on the PdO thin film in methanol oxidation reaction (MOR) in acidic media. The PdO nanoflake thin film exhibits a cyclic voltamperometric (CV) behavior similar to metallic Pd electrodes because a metallic Pd surface layer is formed on the PdO thin film electrode under the CV measurement condition. The nanoflake morphology of the PdO electrode provides a large surface area for Pt nanoparticle loading, resulting in a large electrochemical active surface area (ESA). The Pt/PdO electrode has a high electrocatalytic activity toward MOR, and the good electrocatalytic performance of the Pt/PdO electrode is ascribed to a high CO tolerance and the large ESA. We suggest that the high CO tolerance of the catalyst on the Pt/PdO electrode is a result of the synergism of the bifunctional mechanism and the electronic effect. XPS analyses indicate that negative charge transfer occurs from the PdO support to the Pt nanoparticles, indicating the presence of the electronic effect. Pt nanoparticles on the PdO support can greatly alleviate the nanoflake damage during the CV measurement, which results from anodic dissolution of metal Pd from the PdO support in acidic media. © 2011 Elsevier Ltd. All rights reserved. All rights reserved.

Lo C.-C.,National Chiao Tung University | Chen W.-J.,National Chiao Tung University
Expert Systems with Applications | Year: 2012

Risk assessment is the core process of information security risk management. Organizations use risk assessment to determine the risks within an information system and provide sufficient means to reduce these risks. In this paper, a hybrid procedure for evaluating risk levels of information security under various security controls is proposed. First, this procedure applies the Decision Making Trial and Evaluation Laboratory (DEMATEL) approach to construct interrelations among security control areas. Secondly, likelihood ratings are obtained through the Analytic Network Process (ANP) method; as a result, the proposed procedure can detect the interdependences and feedback between security control families and function in real world situations. Lastly, the Fuzzy Linguistic Quantifiers-guided Maximum Entropy Order-Weighted averaging (FLQ-MEOWA) operator is used to aggregate impact values assessed by experts, applied to diminish the influence of extreme evaluations such as personal views and drastic perspectives. A real world application in a branch office of the health insurance institute in Taiwan was examined to verify the proposed procedure. By analyzing the acquired data, we confirm the proposed procedure certainly detects the influential factors among security control areas. This procedure also evaluates risk levels more accurately by coping with the interdependencies among security control families and determines the information systems safeguards required for better security, therefore enabling organizations to accomplish their missions. © 2011 Elsevier Ltd. All rights reserved.

Hung J.-C.,National Chin - Yi University of Technology | Lin C.-C.,National Chiao Tung University
Journal of Power Sources | Year: 2012

High aspect-ratio micro-flow channels on bipolar plates have the advantage of improving fuel cell performance. This study forms micro-flow channels with a high aspect ratio by increasing the forming pressure during the hydroforming process. This study designs and constructs a mechanical apparatus to enable a two-stage pressure increase in the hydroforming process. A high-pressure container is designed with three-layered tapered cylinders to sustain 1230.17 MPa working pressures, and a special seal component is designed to seal the high-pressure fluid and maintain high pressure. The feasibility of this high-pressure hydroforming technique is verified in preliminary tests. The investigation indicates that the aspect ratio of micro-flow channels can reach 0.468 when a hydrostatic pressure of 250 MPa is applied. Compared with the maximum aspect ratio of 0.31 formed using the traditional hydroforming process, the aspect ratio of micro-flow channels in this study was 51% higher, which enables the fuel cells with metallic bipolar plates to meet both performance and manufacturing requirements. © 2012 Elsevier B.V. All rights reserved.

Lin J.-S.,National Chiao Tung University
Expert Systems with Applications | Year: 2012

As the wafer size increases, the clustering phenomenon of defects becomes significant. In addition to clustered defects, various clustering patterns also influence the wafer yield. In fact, the recognition of clustering pattern usually exists fuzziness. However, the wafer yield models in previous studies did not consider the fuzziness of clustering pattern belonging to which shape in recognition. Therefore, the objective of this study is to develop a new fuzzy variable of clustering pattern (FVCP) by using fuzzy logic control, and predict the wafer yield by using back-propagation neural network (BPNN) incorporating ant colony optimization (ACO). The proposed method utilizes defect counts, cluster index (CI), and FVCP as inputs for ACO-BPNN. A simulated study is utilized to demonstrate the effectiveness of the proposed model. © 2011 Elsevier Ltd. All rights reserved.

Hsu Y.-J.,National Chiao Tung University | Lai Y.,National Chiao Tung University
Optics Express | Year: 2015

Efficient wavelength-selective coupling of lights between sub-wavelength plasmonic waveguides and free space is theoretically investigated. The idea is based on a new type of vertical resonance coupling devices built on plasmonic metal/insulator/metal (MIM) waveguides. The device structure consists of a vertical grating coupler in a resonance cavity formed by two distributed Bragg reflectors (DBRs). With the metal loss included, maximum coupling efficiency around 50% can be obtained at the 1550 nm wavelength with a filtering 3dB bandwidth around 20 nm (7nm for the lossless case), demonstrating the feasibility of the idea for achieving high efficiency wavelength-selective vertical coupling through optical resonance. By utilizing this coupler, a plasmonic add-drop device is proposed and theoretically demonstrated. This kind of compact wavelength selective coupling devices shall have the potential to open up a new avenue of photonics circuitry at nanoscale. © 2015 Optical Society of America.

Tseng W.-H.,MediaTek Inc. | Fan C.-W.,MediaTek Inc. | Wu J.-T.,National Chiao Tung University
IEEE Journal of Solid-State Circuits | Year: 2011

A current-steering digital-to-analog converter (DAC) was fabricated using a 90 nm CMOS technology. Its dynamic performance is enhanced by adopting a digital random return-to-zero (DRRZ) operation and a compact current cell design. The DRRZ also facilitates a current-cell background calibration technique that ensures the DAC static linearity. The measured differential nonlinearity (DNL) is 0.5 LSB and the integral nonlinearity (INL) is 1.2 LSB. At 1.25 GS/s sampling rate, the DAC achieves a spurious-free dynamic range (SFDR) better than 70 dB up to 500 MHz input frequency. The DAC occupies an active area of 1100 × 750 μm2. It consumes a total of 128 mW from a 1.2 V and a 2.5 V supply. © 2011 IEEE.

Hassanfiroozi A.,National Chiao Tung University | Huang Y.-P.,National Chiao Tung University | Javidi B.,University of Connecticut | Shieh H.-P.D.,National Chiao Tung University
Optics Express | Year: 2015

A liquid crystal lens array with a hexagonal arrangement is investigated experimentally. The uniqueness of this study exists in the fact that using convex-ring electrode provides a smooth and controllable applied potential profile across the aperture to manage the phase profile. We observed considerable differences between flat electrode and convex-ring electrode; in particular the lens focal length is variable in a wider range from 2.5cm to infinity. This study presents several noteworthy characteristics such as low driving voltage; 30 μm cell gap and the lens is electrically switchable between 2D/3D modes. We demonstrate a hexagonal LC-lens array for capturing 3D images by using single sensor using integral imaging. © 2015 Optical Society of America.

Yeh C.-H.,Feng Chia University | Chen H.-Y.,Industrial Technology Research Institute of Taiwan | Chow C.-W.,National Chiao Tung University | Liu Y.-L.,Industrial Technology Research Institute of Taiwan
Optics Express | Year: 2015

To increase the traffic rate in phosphor-LED visible light communication (VLC), a multi-band orthogonal frequency division multiplexed (OFDM) modulation is first proposed and demonstrated. In the measurement, we do not utilize optical blue filter to increase modulation bandwidth of phosphor-LED in the VLC system. In this proposed scheme, different bands of OFDM signals are applied to different LED chips in a LED lamp, this can avoid the power fading and nonlinearity issue by applying the same OFDM signal to all the LED chips in a LED lamp. Here, the maximum increase percentages of traffic rates are 41.1%, 17.8% and 17.8% under received illuminations of 200, 500 and 1000 Lux, respectively, when the proposed three-band OFDM modulation is used in the VLC system. In addition, the analysis and verification by experiments are also performed. © 2015 Optical Society of America.

Huang Y.-Y.,National Chiao Tung University | Chou C.,National Chiao Tung University
Computers in Human Behavior | Year: 2010

Cyberbullying, as a serious kind of repeated, intentional, and harmful aggressive behavior, cannot be ignored. In light of the limited studies and inconsistent findings on the matter, this study explores cyberbullying's frequency and other factors (gender, academic achievement, types of technologies used, and anonymity) relevant to both the issue itself and the East Asian context. The interrelationship of different roles (bullies, victims, and bystanders) in cyberbullying is also examined. A survey was conducted with 545 Taiwan junior high school students. The results indicate that male students were more likely to bully others in cyberspace and that cyberbullying was not affected by one's level of academic achievement. Regarding the various technologies and various country-specific cyberbullying forms pertinent to technology users, instant messenger (IM) users experienced significantly more cyberbullying than users of other technologies. The survey results also indicate that the anonymity of cyberbullying was not a pertinent factor. The study found that the dominant attitude toward cyberbullying was indifference, raising alarms about the lack of cyberbullying prevention. Peers, who were the people most teenagers would likely turn to when experiencing cyberbullying, usually took no action because of their tendency to avoid conflicts and to maintain group harmony. In its interpretation of the findings, this study emphasizes Taiwan's context, including Confucian philosophy. © 2010 Elsevier Ltd. All rights reserved.

Shieh M.-Z.,National Chiao Tung University | Tsai S.-C.,National Chiao Tung University
IEEE Transactions on Information Theory | Year: 2010

A frequency permutation array (FPA) of length n=mλ and distance d is a set of permutations on a multiset over m symbols, where each symbol appears exactly λ times and the distance between any two elements in the array is at least d. FPA generalizes the notion of permutation array. In this paper, under the Chebyshev distance, we first prove lower and upper bounds on the size of FPA. Then we give several constructions of FPAs, and some of them come with efficient encoding and decoding capabilities. Moreover, we show one of our designs is locally decodable, i.e., we can decode a message bit by reading at most λ + 1 symbols, which has an interesting application to private information retrieval. © 2006 IEEE.

Chen C.-h.,National Chiao Tung University
Computers and Education | Year: 2010

Recently, more and more researchers have been exploring uses of mobile technology that support new instructional strategies. Based on research findings related to peer and self assessment, this study developed a Mobile Assessment Participation System (MAPS) using Personal Digital Assistants (PDAs) as the platform. In addition, the study proposes an implementation model of the MAPS that should facilitate the effectiveness of self- and peer-assessment in classrooms. The researcher argues that teachers and students can benefit from MAPS in various regards including more flexible assessment arrangement, more efficient use of time, and more opportunities for student reflection on learning and assessment. Thirty-seven students taking teacher-education courses with the researcher participated in this study, and these students employed the MAPS to conduct two-round assessment activities that would help these students assess both their own and one another's final projects. Both the students' valid responses in a survey herein and scores obtained from the assessment activities confirmed the benefits of the MAPS and its implementation model. Yet, the students voiced such concerns as the objectivity of peer-assessment and the difficulty of providing constructive feedback, and the correlation analysis indicated a lack of consistency between teacher-grading and student-grading. © 2010 Elsevier Ltd. All rights reserved.

Li Y.-M.,National Chiao Tung University | Yeh Y.-S.,National Chiao Tung University
Computers in Human Behavior | Year: 2010

The growth of mobile commerce (m-commerce) has motivated a better understanding of how trust can be built on a mobile device. Researchers have previously examined design aesthetics (or visual aesthetics) of mobile website and incorporated a hedonic component of enjoyment in m-commerce domain, but the relationship between design aesthetics of mobile website design and customer trust in m-commerce has been rarely investigated. In this study, design aesthetics was enhanced to include a website characteristics component as important to trust development on the mobile Internet. This model was examined through an empirical study involving 200 subjects using structural equation modeling techniques. Our research found that design aesthetics did significantly impact website characteristics component, especially customization, perceived usefulness and ease of use, all of which were ultimately shown to have significant explanatory power in affecting customer trust. © 2009 Elsevier Ltd. All rights reserved.

Wang C.-C.,National Chiao Tung University | Liaw J.-S.,Industrial Technology Research Institute of Taiwan
International Journal of Heat and Mass Transfer | Year: 2012

This study examines the airside performance of the herringbone wavy fin-and-tube heat exchangers in dehumidifying condition having a larger diameter tube (D c = 16.59 mm) with the tube row ranging from 2 to 12. Test results are compared to that of dry conditions and plain fin geometry. Upon the influence of surface condition (dry or wet) on the heat transfer performance, the heat transfer performance in dehumidifying condition normally exceeds that in dry condition, and is more pronounced with the rise of tube row or reduction of fin pitch. By contrast, it is found that the heat transfer coefficient for plain fin geometry in dehumidifying condition is slightly lower than that in dry condition. The pressure drops in wet condition is much higher than that in dry condition. However, the difference in pressure drop amid dry and dehumidifying condition for wavy fin configuration is less profound as that of plain fin geometry. © 2012 Elsevier Ltd. All rights reserved.

Wang Y.-S.,National Chiao Tung University | Chi M.-T.,National Chengchi University
IEEE Transactions on Visualization and Computer Graphics | Year: 2011

We introduce a focus+context method to visualize a complicated metro map of a modern city on a small displaying area. The context of our work is with regard the popularity of mobile devices. The best route to the destination, which can be obtained from the arrival time of trains, is highlighted. The stations on the route enjoy larger spaces, whereas the other stations are rendered smaller and closer to fit the whole map into a screen. To simplify the navigation and route planning for visitors, we formulate various map characteristics such as octilinear transportation lines and regular station distances into energy terms. We then solve for the optimal layout in a least squares sense. In addition, we label the names of stations that are on the route of a passenger according to human preferences, occlusions, and consistencies of label positions using the graph cuts method. Our system achieves real-time performance by being able to report instant information because of the carefully designed energy terms. We apply our method to layout a number of metro maps and show the results and timing statistics to demonstrate the feasibility of our technique. © 2011 IEEE.

Kim Y.,Chung - Ang University | Lai M.-C.,National Chiao Tung University
Journal of Computational Physics | Year: 2010

In this paper, we develop an immersed boundary (IB) method to simulate the dynamics of inextensible vesicles interacting with an incompressible fluid. In order to take into account the inextensibility constraint of the vesicle, the penalty immersed boundary (pIB) method is used to virtually decouple the fluid and vesicle dynamics. As numerical tests of our current pIB method, the dynamics of single and multiple inextensible vesicles under shear flows have been extensively explored, and compared with the previous literature. The method is also validated by a series of convergence study, which confirms its consistent first-order accuracy on the velocity field, the vesicle configuration, the vesicle area and the perimeter errors. In addition, the method is also applied to study a binary-component vesicle problem. © 2010 Elsevier Inc.

Lin C.-P.,National Chiao Tung University
International Journal of Human-Computer Interaction | Year: 2010

Drawing upon social cognitive theory (SCT), this research postulates several personal and environmental factors as key drivers of virtual community loyalty behavior in online settings. An empirical testing of this model, by investigating undergraduate students' participation in communities of online games, reveals the applicability of SCT in virtual communities. The study's test results show that the influences of both affective commitment and social norms on community loyalty behavior are significant, whereas the influences of both exchange ideology and social support on community loyalty behavior are insignificant. This research contributes to the online community literature by assessing critical antecedent factors to the unexplored area of community loyalty behavior, by validating idiosyncratic drivers of community loyalty behavior and by performing an operationalization of affective commitment and social norms in a virtual world. Last, managerial implications and limitations of this research are provided. © Taylor & Francis Group, LLC.

Liu T.-Y.,National Chiao Tung University | Tsai W.-H.,National Chiao Tung University
IEEE Transactions on Image Processing | Year: 2010

A novel method for generic visible watermarking with a capability of lossless image recovery is proposed. The method is based on the use of deterministic one-to-one compound mappings of image pixel values for overlaying a variety of visible watermarks of arbitrary sizes on cover images. The compound mappings are proved to be reversible, which allows for lossless recovery of original images from watermarked images. The mappings may be adjusted to yield pixel values close to those of desired visible watermarks. Different types of visible watermarks, including opaque monochrome and translucent full color ones, are embedded as applications of the proposed generic approach. A two-fold monotonically increasing compound mapping is created and proved to yield more distinctive visible watermarks in the watermarked image. Security protection measures by parameter and mapping randomizations have also been proposed to deter attackers from illicit image recoveries. Experimental results demonstrating the effectiveness of the proposed approach are also included. © 2010 IEEE.

Chen Z.,National Chiao Tung University | Sun S.-K.,National Chiao Tung University
IEEE Transactions on Image Processing | Year: 2010

A local image descriptor robust to the common photometric transformations (blur, illumination, noise, and JPEG compression) and geometric transformations (rotation, scaling, translation, and viewpoint) is crucial to many image understanding and computer vision applications. In this paper, the representation and matching power of region descriptors are to be evaluated. A common set of elliptical interest regions is used to evaluate the performance. The elliptical regions are further normalized to be circular with a fixed size. The normalized circular regions will become affine invariant up to a rotational ambiguity. Here, a new distinctive image descriptor to represent the normalized region is proposed, which primarily comprises the Zernike moment (ZM) phase information. An accurate and robust estimation of the rotation angle between a pair of normalized regions is then described and used to measure the similarity between two matching regions. The discriminative power of the new ZM phase descriptor is compared with five major existing region descriptors (SIFT, GLOH, PCA-SIFT, complex moments, and steerable filters) based on the precision-recall criterion. The experimental results, involving more than 15 million region pairs, indicate the proposed ZM phase descriptor has, generally speaking, the best performance under the common photometric and geometric transformations. Both quantitative and qualitative analyses on the descriptor performances are given to account for the performance discrepancy. First, the key factor for its striking performance is due to the fact that the ZM phase has accurate estimation accuracy of the rotation angle between two matching regions. Second, the feature dimensionality and feature orthogonality also affect the descriptor performance. Third, the ZM phase is more robust under the nonuniform image intensity fluctuation. Finally, a time complexity analysis is provided. © 2009 IEEE.

Lu C.-C.,National Chiao Tung University | Lu C.-C.,National Taipei University of Technology | Sheu J.-B.,National Taiwan University
Computers and Operations Research | Year: 2013

This work locates urgent relief distribution centers (URDCs) on a given set of candidate sites using a robust vertex p-center (RVPC) model. This model addresses uncertain travel times, represented using fixed intervals or ranges instead of probability distributions, between URDCs and affected areas. The objective of locating a predetermined number (p) of URDCs is to minimize worst-case deviation in maximum travel time from the optimal solution. To reduce the complexity of solving the RVPC problem, this work proposes a property that facilitates identification of the worst-case scenario for a given set of URDC locations. Since the problem is NP-hard, a heuristic framework is developed to efficiently obtain robust solutions. Then, a specific implementation of the framework, based on simulated annealing, is developed to conduct computational experiments. Experimental results show that the proposed heuristic is effective and efficient in obtaining robust solutions of interest. This work examines the impact of the degree of data uncertainty on the selected performance measures and the tradeoff between solution quality and robustness. Additionally, this work demonstrates the applicability of the proposed model to natural disasters based on a real-world instance. The result is compared with that obtained by a scenario-based, two-stage stochastic model. This work contributes significantly to the growing body of literature applying robust optimization approaches to emergency logistics. © 2013 Elsevier Ltd.

Chen Y.-S.,National Chiao Tung University | Hong M.-Y.,National Chiao Tung University | Huang G.S.,National Chiao Tung University
Nature Nanotechnology | Year: 2012

A major challenge in molecular electronics is to attach electrodes to single molecules in a reproducible manner to make molecular junctions that can be operated as transistors. Several attempts have been made to attach electrodes to proteins, but these devices have been unstable. Here, we show that self-assembly can be used to fabricate, in a highly reproducible manner, molecular junctions in which an antibody molecule (immunoglobulin G) binds to two gold nanoparticles, which in turn are connected to source and drain electrodes. We also demonstrate effective gating of the devices with an applied voltage, and show that the charge transport characteristics of these protein transistors are caused by conformational changes in the antibody. Moreover, by attaching CdSe quantum dots to the antibody, we show that the protein transistor can also be gated by an applied optical field. This approach offers a versatile platform for investigations of single-molecule-based biological functions and might also lead to the large-scale manufacture of integrated bioelectronic circuits. © 2012 Macmillan Publishers Limited. All rights reserved.

Noothalapati Venkata H.N.,National Chiao Tung University | Shigeto S.,National Chiao Tung University
Chemistry and Biology | Year: 2012

Lipid droplets have been hypothesized to be intimately associated with intracellular proteins. However, there is little direct evidence for both spatiotemporal and functional relations between lipid droplets and proteins provided by molecular-level studies on intact cells. Here, we present in vivo time-lapse Raman imaging, coupled with stable-isotope (13C) labeling, of single living Schizosaccharomyces pombe cells. Using characteristic Raman bands of proteins and lipids, we dynamically visualized the process by which 13C-glucose in the medium was assimilated into those intracellular components. Our results show that the proteins newly synthesized from incorporated 13C-substrate are localized specifically to lipid droplets as the lipid concentration within the cell increases. We demonstrate that the present method offers a unique platform for proteome visualization without the need for tagging individual proteins with fluorescent probes. © 2012 Elsevier Ltd.

Hu Y.J.,National Chiao Tung University
BMC medical informatics and decision making | Year: 2012

Appropriate postoperative pain management contributes to earlier mobilization, shorter hospitalization, and reduced cost. The under treatment of pain may impede short-term recovery and have a detrimental long-term effect on health. This study focuses on Patient Controlled Analgesia (PCA), which is a delivery system for pain medication. This study proposes and demonstrates how to use machine learning and data mining techniques to predict analgesic requirements and PCA readjustment. The sample in this study included 1099 patients. Every patient was described by 280 attributes, including the class attribute. In addition to commonly studied demographic and physiological factors, this study emphasizes attributes related to PCA. We used decision tree-based learning algorithms to predict analgesic consumption and PCA control readjustment based on the first few hours of PCA medications. We also developed a nearest neighbor-based data cleaning method to alleviate the class-imbalance problem in PCA setting readjustment prediction. The prediction accuracies of total analgesic consumption (continuous dose and PCA dose) and PCA analgesic requirement (PCA dose only) by an ensemble of decision trees were 80.9% and 73.1%, respectively. Decision tree-based learning outperformed Artificial Neural Network, Support Vector Machine, Random Forest, Rotation Forest, and Naïve Bayesian classifiers in analgesic consumption prediction. The proposed data cleaning method improved the performance of every learning method in this study of PCA setting readjustment prediction. Comparative analysis identified the informative attributes from the data mining models and compared them with the correlates of analgesic requirement reported in previous works. This study presents a real-world application of data mining to anesthesiology. Unlike previous research, this study considers a wider variety of predictive factors, including PCA demands over time. We analyzed PCA patient data and conducted several experiments to evaluate the potential of applying machine-learning algorithms to assist anesthesiologists in PCA administration. Results demonstrate the feasibility of the proposed ensemble approach to postoperative pain management.

Vedamalai M.,National Chiao Tung University | Wu S.-P.,National Chiao Tung University
European Journal of Organic Chemistry | Year: 2012

A new boron-dipyrromethene (BODIPY) derivative (FS1) containing two triazole units exhibits an enhanced fluorescence in the presence of Hg 2+ ions and a high selectivity for Hg 2+ ions over competing metal ions in methanol: Ag +, Ca 2+, Cd 2+, Co 2+, Cu 2+, Fe 2+, Fe 3+, K +, Mg 2+, Mn 2+, Ni 2+, Pb 2+, and Zn 2+ produced only minor changes in the fluorescence of FS1. The apparent dissociation constant (K d) of FS1-Hg 2+ was found to be 62 μM. Moreover, fluorescence microscopy experiments showed that FS1 can be used as a fluorescent probe for detecting Hg 2+ ions in living cells. A new BODIPY-based fluorescence chemosensor FS1 shows high selectivity for Hg 2+ ions over other transition-metal ions. The fluorescence of FS1 was significantly enhanced in the presence of Hg 2+, with green emission, and the addition of other metal ions barely affected the fluorescence. This FS1 chemosensor is an effectivemethod for Hg 2+ sensing in living cellimaging. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lai C.-L.,National Chiao Tung University | Hsu P.-L.,National Chiao Tung University
IEEE Transactions on Industrial Informatics | Year: 2010

In real applications, a remote control system is generally an integration of different networks consisting of a commercial network for message transmission and an industrial network to control the remote hardware through a communication gateway. Since the induced time-delay in network control system (NCS) may cause system instability, this paper proposes a remote NCS structure by implementing the adaptive Smith predictor with an online time-delay estimator. As the delay in a commercial network Ethernet is significantly time-varying depending on the number of end-users, the delay is estimated in this paper by processing the online measurement of the round-trip time (RTT) between the application layers of the server and the client. The adaptive Smith predictor control scheme is developed by directly applying the estimated time-delay. To prove the feasibility of the proposed remote control system, the developed design has been applied to an AC 400 W servo motor tested from a 15 km distance. The experimental results indicate that the significantly improved stability and motion accuracy can be reliably achieved by applying the proposed approach. © 2009 IEEE.

Sang T.-H.,National Chiao Tung University
IEEE Transactions on Signal Processing | Year: 2010

The self-duality of short-time Fourier transform (STFT) is an elegant property and is useful in shedding light on the construction of STFT and its resolution capability. In this paper, the discrete version of self-duality is studied, and the property is interpreted in the context of resolution capabilities of time frequency distributions. In addition, two applications are provided as showcases of these insights obtained from the interpretation. In the first application, the problem of STFT synthesis is considered, and self-duality serves as an important indication of whether the synthesis problem at hands is properly formulated. In the second application, a new kind of high-resolution time-frequency distribution is constructed based on the understandings obtained by contrasting two of the most popular time-frequency analysis tools, namely, the STFT and the Wigner distribution. Copyright © 2010 IEEE.

Tseng F.-S.,National Chiao Tung University | Wu W.-R.,National Chiao Tung University
IEEE Transactions on Vehicular Technology | Year: 2010

We consider the precoding problem in an amplify-and-forward (AF) multiple-inputmultiple-output (MIMO) relay system in which multiple antennas are equipped at the source, the relay, and the destination. Most existing methods for this problem only consider the design of the relay precoder, and some even ignore the direct link. In this paper, we consider a joint source/relay precoder design problem, taking both the direct and the relay links into account. Using a minimum-mean-square-error (MMSE) criterion, we first formulate the problem as a constrained optimization problem. However, it is found that the mean square error (MSE) is a highly nonlinear function of the precoders, and a direct optimization is difficult to conduct. We then design the precoders to diagonalize the MSE matrix in the cost function. To do that, we pose certain structural constraints on the precoders and derive an MSE upper bound. It turns out that minimization with respect to this bound becomes simple and straightforward. Using the standard Lagrange technique, we can finally obtain the solution with an iterative water-filling method. Simulation results show that the proposed method, with an additional precoder, outperforms the existing methods, in terms of either the MSE or the bit error rate (BER). © 2010 IEEE.

Chen J.-K.,Tamkang University | Chen I.-S.,National Chiao Tung University
Expert Systems with Applications | Year: 2010

Increasing numbers of Taiwanese higher education institutes are pursuing innovation operation. However, these institutes generally rely greatly on academic research to evaluate innovation performance. Nevertheless, the performance of innovation may be affected by numerous factors that are often beyond the scope of a single academic study. Thus, to address this concern, this paper constructs an innovation support system (ISS) for Taiwanese higher education institutes to comprehensively evaluate their innovation performance. Previous research often evaluates performance by independently considering a number of criteria. However, this assumption of independence does not model the so-called "real world"; thus, we present a novel conjunctive multiple criteria decision-making (MCDM) approach that addresses dependent relationships among each measurement criteria. As such, we utilize a decision-making trial and evaluation laboratory (DEMATEL), a fuzzy analytical network process (FANP), and a technique for order preference by similarity to an ideal solution (TOPSIS) forming order to develop an innovation support system (ISS) that considers the interdependence and the relative weights of each measurement criterion. © 2009 Elsevier Ltd. All rights reserved.

Huang C.-C.,National Chiao Tung University | Wang S.-J.,National Chiao Tung University
IEEE Transactions on Circuits and Systems for Video Technology | Year: 2010

In this paper, from the viewpoint of scene understanding, a three-layer Bayesian hierarchical framework (BHF) is proposed for robust vacant parking space detection. In practice, the challenges of vacant parking space inference come from dramatic luminance variations, shadow effect, perspective distortion, and the inter-occlusion among vehicles. By using a hidden labeling layer between an observation layer and a scene layer, the BHF provides a systematic generative structure to model these variations. In the proposed BHF, the problem of luminance variations is treated as a color classification problem and is tackled via a classification process from the observation layer to the labeling layer, while the occlusion pattern, perspective distortion, and shadow effect are well modeled by the relationships between the scene layer and the labeling layer. With the BHF scheme, the detection of vacant parking spaces and the labeling of scene status are regarded as a unified Bayesian optimization problem subject to a shadow generation model, an occlusion generation model, and an object classification model. The system accuracy was evaluated by using outdoor parking lot videos captured from morning to evening. Experimental results showed that the proposed framework can systematically determine the vacant space number, efficiently label ground and car regions, precisely locate the shadowed regions, and effectively tackle the problem of luminance variations. © 2006 IEEE.

Chang K.-H.,The Academy of Management | Wen T.-C.,National Chiao Tung University
Expert Systems with Applications | Year: 2010

Design Failure Mode and Effect Analysis (DFMEA) is the application of the Failure Mode and Effects Analysis (FMEA) method specifically to product design. DFMEA is not only an important risk assessment technique but also a major task for enterprises in implementing production management. The purpose is to ensure that the product can achieve its designed functions under specific operating conditions. Most current DFMEA methods use the Risk Priority Number (RPN) value to evaluate the risk of failure. However, conventional RPN methodology has the serious problem of measurement scales and loses some valued information, which experts have to provide. In order to improve the method of RPN evaluation, this paper proposes a novel technique, combining 2-tuple and the Ordered Weighted Averaging (OWA) operator for prioritization of failures in a product DFMEA. A case of the Color Super Twisted Nematic (CSTN) that has been drawn from a midsized manufacturing factory is presented to further illustrate the proposed approach. After comparing the result that was obtained from the proposed method with the other two listed approaches, it was found that the proposed approach can effectively solve the problem of measurement scales and has not lost any expert to provide the useful information. As a result, stability of the product and process can be assured. © 2009 Elsevier Ltd. All rights reserved.

Wang C.-C.,National Chiao Tung University
Heat Transfer Engineering | Year: 2012

A new concept of heat transfer enhancement applicable for finned tube air-cooled heat exchangers is proposed. The concept called a 'partial bypass' arises from an effective usage of the ineffective air stream (bypass airflow). The concept is rather simple, focusing on increasing the Q max at the rear part of the heat exchanger. The concept can be implemented either with substantial increase of heat transfer rate without additional pressure drop penalty or with identical heat transfer rate but accompanies a much smaller pressure drop. Both the temperature difference amid inlet air and water and the mass flow rate into the second heat exchanger can be increased simultaneously. This eventually leads to an even higher Q max at the second heat exchanger and as a result a much larger heat transfer rate. The concept is especially helpful in the design of a deep tube bank and can be implemented with sufficient augmentation without additional penalty.

Sze S.M.,National Chiao Tung University
Journal of Nanoscience and Nanotechnology | Year: 2012

In the past 45 years (from 1967 to 2012), the non-volatile semiconductor memory (NVSM) has emerged from a floating-gate concept to the prime technology driver of the largest industry in the world\-the electronics industry. In this paper, we briefly review the historical development of NVSM and project its future trends to the year 2020. In addition, we consider NVSM's wide-range of applications from the digital cellular phone to tablet computer to digital television. As the device dimension is scaled down to the deca-nanometer regime, we expect that many innovations will be made to meet the scaling challenges, and NVSM-inspired technology will continue to enrich and improve our lives for decades to come. Copyright © 2012 American Scientific Publishers. All rights reserved.

Lai Y.-L.,National Chiao Tung University | Chen C.-C.,National Chiao Tung University | Hwang J.-K.,National Chiao Tung University
Nucleic Acids Research | Year: 2012

Knotted proteins have recently received lots of attention due to their interesting topological novelty as well as its puzzling folding mechanisms. We previously published a pKNOT server, which provides a structural database of knotted proteins, analysis tools for detecting and analyzing knotted regions from structures as well as a Java-based 3D graphics viewer for visualizing knotted structures. However, there lacks a convenient platform performing similar tasks directly from 'protein sequences'. In the current version of the web server, referred to as pKNOT v.2, we implement a homology modeling tool such that the server can now accept protein sequences in addition to 3D structures or Protein Data Bank (PDB) IDs and return knot analysis. In addition, we have updated the database of knotted proteins from the current PDB with a combination of automatic and manual procedure. We believe that the updated pKNOT server with its extended functionalities will provide better service to biologists interested in the research of knotted proteins. The pKNOT v.2 is available from http://pknot.life.nctu.edu.tw/. © 2012 The Author(s).

Chen Y.-C.,National Chiao Tung University | Pu Y.-C.,National Chiao Tung University | Hsu Y.-J.,National Chiao Tung University
Journal of Physical Chemistry C | Year: 2012

The interfacial charge carrier dynamics of the three-component semiconductor-semiconductor-metal heterojunction system were investigated and presented for the first time. The samples were prepared by selectively depositing Pt nanoparticles on the TiO 2 surface of In 2O 3-decorated TiO 2 nanobelts (In 2O 3-TiO 2 nanobelts (NBs)) using the typical photodeposition method. For In 2O 3-TiO 2 NBs, because of the difference in band structures between In 2O 3 and TiO 2, the photoexcited electrons of In 2O 3 nanocrystals would preferentially transfer to TiO 2 NBs to cause charge carrier separation. With the introduction of Pt on TiO 2 surface, a fluent electron transfer from In 2O 3, through TiO 2, and eventually to Pt was achieved, giving rise to the increasingly pronounced charge separation property for the as-prepared In 2O 3-TiO 2-Pt NBs. The remarkable charge separation of the samples was revealed with the corresponding photocurrent measurements. Time-resolved photoluminescence spectra were measured to quantitatively analyze the electron transfer event between In 2O 3 and TiO 2 for In 2O 3-TiO 2 NBs and its dependence on Pt deposition. Upon the deposition of Pt, In 2O 3-TiO 2 NBs showed an increased apparent electron-scavenging rate constant, fundamentally consistent with the result of their performance evaluation in photocatalysis. The current study provides a new paradigm for designing highly efficient three-component nanoheterojunction photocatalysts which can effectively produce chemical energy from absorbing light. © 2012 American Chemical Society.

Wang H.,National Chiao Tung University
Current Pharmaceutical Biotechnology | Year: 2014

MicroRNAs (miRNAs) are small, noncoding RNAs with important functions in development, cell differentiation, and regulation of cell cycle and apoptosis. Many studies have now shown that miRNAs are involved in the initiation and progression of cancers. In this study, procedures based on the relative R-squared method (RRSM) are proposed to investigate miRNA-mRNA regulatory relationships between 114 miRNAs and 16063 mRNAs for different organic tissues. These procedures are based on comparing the expression profiles in tumor tissue and those in normal tissues, or based on the expression profiles in tumor tissue only. The analyzed results are used to predict high-confident miRNAs for tumor development and their targets. This study predicts many high-confident miRNAs which are associated with colon cancer, prostate cancer, pancreatic cancer, lung cancer, breast cancer, bladder cancer and kidney cancer, respectively. © 2014 Bentham Science Publishers.

Huang C.-W.,National Chiao Tung University | Chen J.-Y.,National Chiao Tung University | Chiu C.-H.,National Chiao Tung University | Wu W.-W.,National Chiao Tung University
Nano Letters | Year: 2014

One dimensional metal oxide nanostructures have attracted much attention owing to their fascinating functional properties. Among them, piezoelectricity and photocatalysts along with their related materials have stirred significant interests and widespread studies in recent years. In this work, we successfully transformed piezoelectric ZnO into photocatalytic TiO2 and formed TiO2/ZnO axial heterostructure nanowires with flat interfaces by solid to solid cationic exchange reactions in high vacuum (approximately 10 -8 Torr) transmission electron microscope (TEM). Kinetic behavior of the single crystalline TiO2 was systematically analyzed. The nanoscale growth rate of TiO2 has been measured using in situ TEM videos. On the basis of the rate, we can control the dimensions of the axial-nanoheterostructure. In addition, the unique Pt/ ZnO / TiO2/ ZnO /Pt heterostructures with complementary resistive switching (CRS) characteristics were designed to solve the important issue of sneak-peak current. The resistive switching behavior was attributed to the migration of oxygen and TiO2 layer served as reservoir, which was confirmed by energy dispersive spectrometry (EDS) analysis. This study not only supplied a distinct method to explore the transformation mechanisms but also exhibited the potential application of ZnO/TiO2 heterostructure in nanoscale crossbar array resistive random-access memory (RRAM). © 2014 American Chemical Society.

Tsai W.-J.,National Chiao Tung University
IEEE Transactions on Circuits and Systems for Video Technology | Year: 2010

Transmission of compressed video signals over error-prone networks exposes the information to losses and errors. To reduce the effects of these losses and errors, this paper presents a joint spatial-temporal estimation method which takes advantages of data correlation in these two domains for better recovery of the lost information. The method is designed for the hybrid multiple description coding which splits video signals along spatial and temporal dimensions. In particular, the proposed method includes fixed and content-adaptive approaches for estimation method selection. The fixed approach selects the estimation method based on description loss cases, while the adaptive approach selects the method according to pixel gradients. The experimental results demonstrate that improved error resilience can be accomplished by the proposed estimation method. © 2006 IEEE.

Tsai S.-H.,National Chiao Tung University | Poor H.V.,Princeton University
IEEE Transactions on Signal Processing | Year: 2014

This paper investigates the power allocation problem for artificial noise (AN) secure precoding systems, and proposes closed-form solutions for maximizing the achievable secrecy rate. It is assumed that the transmitter knows the full channel information at the legitimate receiver, and knows only the statistics of the channel information at the eavesdropper. Lower bounds are derived for the secrecy rates in multiple-input single-output channels with single or multiple eavesdroppers and multiple-input multiple-output channels with multiple eavesdroppers. When the number of transmit antennas is sufficiently large, the bounds are tight, and closed-form solutions can be derived from these bounds. The analytical results suggest simple and yet informative solutions as follows: Let the numbers of receive antennas at the legitimate receiver and at the eavesdropper be Nr and Nr,e, respectively. The system should distribute Nr,e (Nr+Nr,e of the power to AN in the high SNR regime, and distribute zero power to AN in the low SNR regime; the rate loss due to the eavesdropper is -Nr log N r (Nr+Nr,e-Nr,e log Nr,e (Nr+Nr,e bits/sec/Hz in the high SNR regime and nearly negligible in the low SNR regime. The derived results also show that equal power and water-filling power allocations lead to similar solutions and rate loss. Simulation results corroborate the theoretical results. © 1991-2012 IEEE.

Hung Y.-C.,National Chiao Tung University | Tsai S.-H.L.,National Chiao Tung University
IEEE Transactions on Wireless Communications | Year: 2014

Beamforming (or precoding) techniques have been widely adopted in modern MIMO OFDM systems. Using beamforming can significantly improve the receive SNR of OFDM systems. However, the combination of transmit signals after beamforming deteriorates the peak-to-average power ratio (PAPR), which has long been considered a major issue of OFDM systems. High PAPR not only complicates the design of the power amplifier, but also increases power consumption. In this paper, we theoretically analyze the PAPR performance of MIMO OFDM systems that adopt either one of the two popular beamforming schemes, i.e. MRT (maximum ratio transmission) and EGT (equal gain transmission). The analysis considers different numbers of channel taps after sampling. The results may provide important reference for practical designs when evaluating the required power amplifiers and power consumption. Moreover, the theoretical results show that MRT OFDM systems generally perform much worse than EGT OFDM systems in terms of PAPR. Furthermore, motivated from the derived results, PAPR reduction algorithms are proposed for both MRT OFDM and EGT OFDM systems. It is worth to mention that for MRT OFDM systems, the proposed algorithm can improve both PAPR and bit error rate; for EGT OFDM systems, the proposed algorithm improves PAPR while it only slightly degrades bit error rate. © 2002-2012 IEEE.

Chen H.-C.,National Chiao Tung University
IEEE Transactions on Industrial Electronics | Year: 2014

Multiphase boost-type switch-mode rectifiers (SMRs) are often used to improve the efficiency of ac-dc conversion. In particular, the light-load efficiency can be increased by turning off some phases (i.e., phase-shedding operation). To keep the number of feedback signals fixed regardless of the topology phase number N, the interleaved current sensorless control (ICSC) with consideration of the phase-shedding operation is proposed in this paper. In ICSC, no current sensing is needed, and only input and output voltages are sensed. To demonstrate the proposed ICSC, a two-phase boost-type SMR is established for test, and the proposed ICSC is implemented in a field-programmable-gate-array-based system. The provided simulation and experimental results show good performance of the proposed ICSC. © 1982-2012 IEEE.

Jia W.-K.,National Chiao Tung University
IEEE Journal on Selected Areas in Communications | Year: 2014

This paper introduces a new scalable, efficient and stateless source routing scheme to ensure that unified unicast and multicast packets can be delivered in the Data Center Networks (DCNs). This scheme, called Code-Oriented eXplicit multicast (COXcast), is based on unicast and eXplicit multicast (Xcast). It constructs the unicast path and multicast tree by encoding the corresponding output port bitmap of each intermediate node. Using a common identifier and a node-specific key, so packets can be self-routed to multiple receivers without requiring header modification. In addition, intermediate switches/routers on the path/tree can be stateless. Compared to traditional source-based unicasting and explicit-based multicasting schemes, COXcast has lowered the processing cost, protocol overhead and delivery latency, while simplifying the deployment and management of a large number of medium-scale multicast groups, especially when applied to large-scale DCNs. © 2013 IEEE.

Liu S.-R.,National Chiao Tung University | Wu S.-P.,National Chiao Tung University
Sensors and Actuators, B: Chemical | Year: 2012

A new rhodamine-based chemosensor exhibits excellent selectivity for Fe 3+ ions over a wide range of tested metal ions Ag +, Al 3+, Ca 2+, Cd 2+, Co 2+, Cr 3+, Cu 2+, Fe 2+, Hg 2+, Mg 2+, Mn 2+, Ni 2+, Pb 2+, and Zn 2+ in an aqueous solution. The binding of Fe 3+ to chemosensor 1 produces an absorption band at 564 nm and an emission band at 588 nm because Fe 3+-binding induces ring-opening of the spirolactam in 1. The binding ratio of the 1-Fe 3+ complexes was determined to be 1:1 according to a Job plot. The association constant (K a) of Fe 3+ binding in chemosensor 1 was 6.9 × 10 3 M -1. The maximum fluorescence enhancement caused by Fe 3+ binding in chemosensor 1 occurred at a pH range of 6-7.5. The fluorescence microscopy experiments in this study demonstrated that chemosensor 1 can be used as a fluorescent probe for detecting Fe 3+ in living cells. © 2012 Elsevier B.V. All rights reserved.

Chiu C.-H.,National Chiao Tung University | Chu C.-S.,National Chiao Tung University
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

Pseudospin flipping is found to be the key process leading to the formation of an edge-potential-induced edge state at an armchair-graphene open boundary and nanoribbons. At an open boundary, the edge potential U 0 is shown to turn on pseudospin-flipped (intravalley) scattering even though U 0 does not post an apparent breaking of the AB site (basis atoms) symmetry. For a valley-polarized incident beam, the interference between the pseudospin-conserving (intervalley) and -nonconserving (intravalley) processes in the scattering state leads to a finite out-of-plane pseudospin density. This two-wave feature in the evanescent regime leads to the formation of the edge state. The physical origin of the edge state is different from that for the Tamm states in semiconductors. For an armchair-graphene nanoribbon with a gapless energy spectrum, applying U 0 to both edges opens up an energy gap. Both edge states and energy gap opening exhibit distinct features in nanoribbon conductance. © 2012 American Physical Society.

Kang C.-H.,National Chiao Tung University | Wu S.-J.,National Chiao Tung University | Tarng J.-H.,National Chiao Tung University
IEEE Transactions on Antennas and Propagation | Year: 2012

A novel folded ultrawideband antenna forWireless Body Area Network (WBAN) is proposed, which can effectively reduce the backward radiation and proximity effects of human bodies. The proposed antenna has a low-profile 3D structure that consists of a bevel-edge feed structure and a metal plate with folded strip. The bevel edge feed structure achieves broadband impedance matching and the metal plate acts as the main radiator. Moreover, the folded strip not only extends the lower frequency band but also provides additional resonant frequency around 6 GHz. The final bandwidth covers from 3.1 GHz to 12 GHz. The proposed antenna shows the directional patterns with low backward radiation due to the patchlike structure and the ground plane also prevents from the proximity effects of human bodies. Furthermore, the simulated SAR values of the proposed antenna are lower than the values of omnidirectional disc planar monopole. These features demonstrate that the proposed antenna is suitable for WBAN application. © 2011 IEEE.

Chi P.-L.,National Chiao Tung University
IEEE Microwave and Wireless Components Letters | Year: 2012

A novel and miniaturized ring coupler capable of presenting arbitrary power divisions is proposed using the composite right/left-handed (CRLH) transmission lines. The unbalanced CRLH transmission lines that can be easily tailored to implement transmission lines of high or low Bloch impedance are applied to enhance the coupler's capability of arbitrary power divisions. To support our idea, a ring coupler that offers a 6 dB power division ratio and occupies only 44% of the conventional footprint was experimentally realized. Experimental results agree well with the simulation data. The proposed CRLH configuration demonstrates an alternative for implementing a compact ring coupler with arbitrary power division ratios. © 2012 IEEE.

Chang S.-W.,Academia Sinica, Taiwan | Chang S.-W.,National Chiao Tung University
IEEE Journal on Selected Topics in Quantum Electronics | Year: 2012

We present a convenient and self-consistent approach to calculate confinement factors and modal volumes of micro- and nanocavities, which are important for ultrasmall lasers and cavity quantum electrodynamics. This scheme does not rely on the numerical integrations related to optical fields and can avoid the indefinite dependence of physical quantities on integration regions. As a result of this built-in invariance to integration regions, the field representation of the confinement factor, in additional to its conventional expression, contains counter terms of volume and surface integrals, which cancel the effect of arbitrary integration volumes. This procedure is useful for small open cavities or those without sharp boundaries that distinguish cavity regions from free spaces. The uncertainty from different choices of integration regions can be thus eliminated. © 1995-2012 IEEE.

Kuo Y.-T.,National Chiao Tung University | Chang C.-Y.,National Chiao Tung University
IEEE Transactions on Microwave Theory and Techniques | Year: 2012

This paper presents a novel analytical approach for designing two-mode dual-band bandpass filters using E-shaped resonators. Based on the dual-band coupling matrix, the dimensions of the filter configuration are extracted via even- and odd-mode analysis of E-shaped resonators. The back-to-back E-shaped resonators provide the out-of-phase property by coupling at specific edges, and it produces good selectivity for dual-band characteristics. The proposed filters have the advantage of compact size and satisfy various requirements of filter orders and coupling coefficients at both passbands. The transmission zeros are successfully introduced into each passband in both filters. To verify the proposed method, two filters are implemented using microstrip technology. The measured results exhibit two-mode dual-band bandpass responses and agree well with simulations. © 2006 IEEE.

Lin Y.-P.,National Chiao Tung University
IEEE Transactions on Signal Processing | Year: 2014

In this paper we consider variable-rate transmission for time-correlated MIMO (multi-input multi-output) channels with limited feedback. The number of bits loaded on each subchannel of the MIMO system is dynamically assigned according to the current channel condition and fed back to the transmitter. As the channel is time-correlated, bit loading is a vector signal that is also time-correlated. We propose to feedback bit loading using predictive coding, which is known to be a powerful quantization technique when the underlying signal is correlated in time. Assuming the channel is a first-order Gauss-Markov random process, we derive the predictor for the bit loading to be coded and analyze the corresponding prediction error variance when the channel is varying slowly. By exploiting the prediction error variance, we adapt the quantizer of the prediction error to have a smaller quantization error. Furthermore we show that the prediction error variance is proportional to a term that depends only on the time-correlation coefficient. This leads to the conclusion that, a codebook that is designed for a particular time correlation coefficient can be easily modified to a codebook for a different correlation coefficient without redesign. Simulations are presented to demonstrate that the proposed predictive coding can achieve a very good approximation of the desired transmission rate with a very low feedback rate. © 2014 IEEE.

Lin Y.-Y.,National Chiao Tung University | Chang J.-Y.,National Chiao Tung University | Lin C.-T.,National Chiao Tung University
IEEE Transactions on Industrial Electronics | Year: 2014

In this paper, a Takagi-Sugeno-Kang (TSK)-type-based self-evolving compensatory interval type-2 fuzzy neural network (FNN) (TSCIT2FNN) is proposed for system modeling and noise cancellation problems. A TSCIT2FNN uses type-2 fuzzy sets in an FNN in order to handle the uncertainties associated with information or data in the knowledge base. The antecedent part of each compensatory fuzzy rule is an interval type-2 fuzzy set in the TSCIT2FNN, where compensatory-based fuzzy reasoning uses adaptive fuzzy operation of a neural fuzzy system to make the fuzzy logic system effective and adaptive, and the consequent part is of the TSK type. The TSK-type consequent part is a linear combination of exogenous input variables. Initially, the rule base in the TSCIT2FNN is empty. All rules are derived according to online type-2 fuzzy clustering. For parameter learning, the consequent part parameters are tuned by a variable-expansive Kalman filter algorithm to the reinforce parameter learning ability. The antecedent type-2 fuzzy sets and compensatory weights are learned by a gradient descent algorithm to improve the learning performance. The performance of TSCIT2FNN for the identification is validated and compared with several type-1 and type-2 FNNs. Simulation results show that our approach produces smaller root-mean-square errors and converges more quickly. © 1982-2012 IEEE.

This study compared clicker technology against mobile polling and the Just-in-Time Teaching (JiTT) strategy to investigate how these methods may differently affect students' anxiety, self-efficacy, engagement, academic performance, and attention and relaxation as indicated by brainwave activity. The study utilized a quasi-experimental research design. To assess the differences between the effects of clickers and mobile polling, the study collected data from two courses at a large research university in Taiwan in which 69 students used either clickers or mobile polling. The results showed that mobile polling along with the JiTT strategy and in-class polls reduce graduate students' anxiety, improve student outcomes in an environment comprising both graduate and undergraduate students, and increase students' attention during polling. However, brainwave data revealed that during the polling activities, students' attention in the clicker and mobile polling groups respectively increased and decreased. Students nowadays do not find smartphones a novelty; however, incorporating them into class is still a potentially effective way to increase student attention and provide a direct way for instructors to observe the learning effects of lectures and improve their teaching approach on that basis. © 2013 Elsevier Ltd. All rights reserved.

Chang L.-H.,National Chiao Tung University | Wu J.-Y.,National Chiao Tung University
IEEE Transactions on Information Theory | Year: 2014

A sufficient condition reported very recently for perfect recovery of a K-sparse vector via orthogonal matching pursuit (OMP) in K iterations (when there is no noise) is that the restricted isometry constant (RIC) of the sensing matrix satisfies δK+1 <(1K+1). In the noisy case, this RIC upper bound along with a requirement on the minimal signal entry magnitude is known to guarantee exact support identification. In this paper, we show that, in the presence of noise, a relaxed RIC upper bound δK+1 < 4K+1-1/2K together with a relaxed requirement on the minimal signal entry magnitude suffices to achieve perfect support identification using OMP. In the noiseless case, our result asserts that such a relaxed RIC upper bound can ensure exact support recovery in K iterations: this narrows the gap between the so far best known bound δK+1 <(1K+1) and the ultimate performance guarantee δK+1=(1/K). Our approach relies on a newly established near orthogonality condition, characterized via the achievable angles between two orthogonal sparse vectors upon compression, and, thus, better exploits the knowledge about the geometry of the compressed space. The proposed near orthogonality condition can be also exploited to derive less restricted sufficient conditions for signal reconstruction in two other compressive sensing problems, namely, compressive domain interference cancellation and support identification via the subspace pursuit algorithm. © 1963-2012 IEEE.

Wu J.-Y.,National Chiao Tung University
Journal of Computer Assisted Learning | Year: 2014

This study examined how knowledge of metacognitive strategies and navigation skills mediate the relationship between online reading activities and printed reading assessment (PRA) and electronic reading assessment (ERA) across 19 countries using the PISA (Programme for International Student Assessment) 2009 database. Participants were 34104 fifteen-year-old students (female: 50.1%). The results showed that information-seeking activity, knowledge of metacognitive strategies and navigations skills positively predicted ERA and PRA. Social reading activities negatively predicted knowledge of metacognitive strategies and PRA but had no effect on ERA and the navigation skills in most countries. Increased information-seeking reading resulted in higher ERA and PRA as demonstrated by navigation skills and knowledge of metacognitive strategies. Gender differences in online reading engagement were not statistically significant in most countries. However, girls performed better in knowledge of metacognitive strategies, navigation skills and PRA but were not significantly better on ERA. Multiple group comparisons of gender indicated that the hypothesized model held for both boys and girls. Besides the infrastructure of information and communications technology as a tool to access the cyber informational space, students should be empowered to use appropriate strategies and navigation skills to achieve their goals. Implications for teaching and learning practices are discussed. © 2014 John Wiley & Sons Ltd.

Chen K.-Y.,National Chiao Tung University | Lai M.-C.,National Chiao Tung University
Journal of Computational Physics | Year: 2013

Many physical problems arising in biological or material sciences involve solving partial differential equations in deformable interfaces or complex domains. For instance, the surfactant (an amphiphilic molecular) which usually favors the presence in the fluid interface may couple with the surfactant soluble in one of bulk domains through adsorption and desorption processes. Thus, it is important to accurately solve coupled surface-bulk convection-diffusion equations especially when the interface is moving. In this paper, we first rewrite the original bulk concentration equation in an irregular domain (soluble region) into a regular computational domain via the usage of the indicator function so that the concentration flux across the interface due to adsorption and desorption processes can be termed as a singular source in the modified equation. Based on the immersed boundary formulation, we then develop a new conservative scheme for solving this coupled surface-bulk concentration equations which the total surfactant mass is conserved in discrete sense. A series of numerical tests has been conducted to validate the present scheme. As an application, we extend our previous work [M.-C. Lai, Y.-H. Tseng, H. Huang, An immersed boundary method for interfacial flows with insoluble surfactant, J. Comput. Phys. 227 (2008) 7279-7293] to the soluble case. The effects of solubility of surfactant on drop deformations in a quiescent and shear flow are investigated in detail. © 2013 Elsevier Inc.

Tsai K.-A.,National Chiao Tung University | Hsu Y.-J.,National Chiao Tung University
Applied Catalysis B: Environmental | Year: 2015

We demonstrated the use of CdSe/graphene quantum dot (QD) nanoheterostructures as the photoanode for remarkable photoelectrochemical hydrogen production. By employing a delicate hydrothermal cutting approach, reduced graphene oxide (RGO) sheets with the lateral size in a desirable range can be obtained, from micrometer size (micro-RGO), to 30-100. nm (nano-RGO), and to 2-4. nm (QD-RGO). Because of the significant zigzag edge effect, nano-RGO and QD-RGO possessed well-defined band structure which enabled efficient light absorption and distinctive photoluminescence emission. Time-resolved photoluminescence spectra showed that nano-RGO and QD-RGO surpassed micro-RGO in enhancing the charge separation efficiency of CdSe. According to the cyclic voltammetry data, a type-II vectorial charge transfer model was considered for CdSe/nano-RGO and CdSe/QD-RGO nanoheterostructures, fundamentally different from the unidirectional electron transfer mechanism of CdSe/micro-RGO. Among the three CdSe/RGO samples tested, CdSe/QD-RGO achieved the highest photocurrent generation in the photoelectrochemical cell, which exceeded 5 times the value of CdSe. The incident photon-to-electron conversion efficiency (IPCE) spectra suggested that the significantly enhanced photoactivity of CdSe/QD-RGO originated from the type-II vectorial charge transfer feature, which not only promoted charge carrier separation but also improved the overall light harvesting. Furthermore, no appreciable decay of photocurrent was found for CdSe/QD-RGO after continuously used in the photoelectrochemical cell for over 2. h, revealing its substantially high stability during the water reduction process. The demonstrations from this work may facilitate the use of graphene QDs in semiconductor-based photocatalysis, in which the efficient light harvesting and high chemical inertness of graphene QDs can be well employed. © 2014 Elsevier B.V.

Regulation of pre-mRNA splicing is achieved through the interaction of RNA sequence elements and a variety of RNA-splicing related proteins (splicing factors). The splicing machinery in humans is not yet fully elucidated, partly because splicing factors in humans have not been exhaustively identified. Furthermore, experimental methods for splicing factor identification are time-consuming and lab-intensive. Although many computational methods have been proposed for the identification of RNA-binding proteins, there exists no development that focuses on the identification of RNA-splicing related proteins so far. Therefore, we are motivated to design a method that focuses on the identification of human splicing factors using experimentally verified splicing factors. The investigation of amino acid composition reveals that there are remarkable differences between splicing factors and non-splicing proteins. A support vector machine (SVM) is utilized to construct a predictive model, and the five-fold cross-validation evaluation indicates that the SVM model trained with amino acid composition could provide a promising accuracy (80.22%). Another basic feature, amino acid dipeptide composition, is also examined to yield a similar predictive performance to amino acid composition. In addition, this work presents that the incorporation of evolutionary information and domain information could improve the predictive performance. The constructed models have been demonstrated to effectively classify (73.65% accuracy) an independent data set of human splicing factors. The result of independent testing indicates that in silico identification could be a feasible means of conducting preliminary analyses of splicing factors and significantly reducing the number of potential targets that require further in vivo or in vitro confirmation.

Cheng K.-H.,National Chiao Tung University | Tsai C.-C.,National Taiwan University of Science and Technology
Computers and Education | Year: 2014

Previous studies on augmented reality (AR) book learning have not provided an in-depth examination of the learning process, especially the interaction involved in child-parent shared book reading. Choosing an AR picture book to introduce its artistic work, this study aimed to explore how children and parents read the book through a series of analyses of behavioral patterns and cognitive attainment. A total of 33 child-parent pairs voluntarily participated in this study. Based on the indicators of the child-parent reading behaviors generated through content analysis, four behavioral patterns of AR picture book reading were identified: parent as dominator, child as dominator, communicative child-parent pair, and low communicative child-parent pair. The relationships between the child-parent reading behaviors and the children's cognitive attainment were further identified. Specifically, the child-parent behaviors of "parent as dominator" and "low communicative child-parent pair" were likely associated with simple description of the appearance of the artistic work by the children (low-level cognitive attainment). Conversely, the "child as dominator" and "communicative child-parent pair" behaviors resulted in the children explaining the artistic work they had seen or using their imagination to describe the content of the book (high-level cognitive attainment). © 2013 Elsevier Ltd. All rights reserved.

Chen C.-H.,National Chiao Tung University | Chiu C.-H.,National Chiao Tung University
IEEE Journal of Quantum Electronics | Year: 2010

We present a design technique for a compact waveguide crossing by using a 90° multimode-interference (MMI) based waveguide crossing sandwiched by four identical miniaturized tapers where the power of the input guided mode is coupled into even modes of the MMI section at a specific power ratio and with different phases, thereby reducing the dimension of this waveguide crossing with imperceptible loss and crosstalk. Using the finite difference time domain method, we demonstrate that the MMI-based waveguide crossing embedded in short Gaussian tapers has a size 5426 nm × 5426 nm, insertion loss 0.21 dB, and crosstalk -44.4 dB at the wavelength of 1550 nm and broad transmission spectrum ranging from 1500 to 1600 nm. © 2010 IEEE.

Su Y.-W.,National Chiao Tung University | Lan S.-C.,National Chiao Tung University | Wei K.-H.,National Chiao Tung University
Materials Today | Year: 2012

In the last ten years, the highest efficiency obtained from organic photovoltaics (OPVs), such as bulk heterojunction polymer:fullerene solar cells, has risen from 2.5 to 11 %. This rapid progress suggests that the commercialization of OPVs should be realized soon if we can solve some technical issues. The advances in the development of OPVs can be attributed to four fronts: (i) a better understanding of the mechanism of photon-to-electron conversion; (ii) new materials with tailored energy levels and solubility; (iii) new processing approaches to induce optimal microstructures in the active layer; and (iv) new device architectures with novel interfacial layers. Herein, we review the materials, the microstructures of the active layers, the device structures, the interfacial layers that have been developed recently for OPVs, and provide future perspectives for this promising technology. © 2012 Elsevier Ltd.

Sheu J.-B.,National Chiao Tung University
Transportmetrica A: Transport Science | Year: 2013

Incident-induced driver behaviour modelling is essential to analyse non-recurrent traffic congestion problems. However, such research is inadequate in such areas as traffic flow prediction, traffic simulation and incident management. This article presents microscopic lane traffic models to characterise incident-induced driver behaviour including car following and lane changing conducted under conditions of lane-blocking arterial incidents. To demonstrate the validity of the proposed models, a specific microscopic traffic simulation program embedded with the proposed incident-induced lane traffic behaviour models is tested by comparing simulation data with video-based incident data collected from five incident events. Preliminary test results indicate that the proposed microscopic traffic behaviour models permit not only reproducing incident-induced traffic behaviour but also characterising incident effects on lane traffic phenomena. © 2013 Copyright Hong Kong Society for Transportation Studies Limited.

Chen M.-F.,Tatung University | Huang C.-H.,National Chiao Tung University
Food Control | Year: 2013

This study aims to ascertain whether or not the Food Traceability System (FTS) can decrease an individual's perceived uncertainty and strengthen his/her purchase intention regarding fast foods. A website-based questionnaire study was conducted in Taiwan and a total of 435 valid subjects collected. The empirical results of structural equation modeling (SEM) analysis indicate that when a fast food store adopts FTS then consumers' perceived uncertainty can be reduced because both their perceived information asymmetry and fears of seller opportunism are also reduced, which in turn strengthen their purchase intentions regarding fast foods. In addition, with FTS, not only are both consumers' perceived product diagnosticity and informativeness are increased but consumers' trust in the farmer's records kept for this system is also increased, which in turn mitigate both consumers' perceived information asymmetry and fears of seller opportunism. Finally, the higher the degree of involvement an individual has and the more FTS mitigates his/her perceived uncertainty, the higher his/her purchase intention regarding fast foods than otherwise. Based on the findings from this study, attempts are made to provide some suggestions to the public health sector and the fast food marketers to promote FTS. © 2013 Elsevier Ltd.

Lin J.-S.,MediaTek | Feng K.-T.,National Chiao Tung University
IEEE Transactions on Wireless Communications | Year: 2014

In recent years, femtocell plays an important role in wireless networks not only for its spectrum reuse but also for its low power consumption. However, there exist several critical issues that need to be investigated, especially for the interferences between the macrocell BSs (mBSs) and femtocell BSs (fBSs). The level of interference mainly depends on the access strategies of fBSs. Two major access policies are considered in femtocell network, including the closed access mode and open access mode. The closed access mode only permits authorized subscribers to utilize the fBS; while all users are allowed to connect to the fBS by adopting the open access mode. Closed access will intuitively be advantageous to the femtocell subscribers, however, interference from the fBS to mBS's users can become severe in the closed access mode than in open access mode. System performance of the entire heterogeneous network (HetNet) can be improved if fBS is operated in the open access mode. In order to relax the inflexible access strategies, hybrid access policy is considered in this paper which allows nonsubscribers to possess limited connections to the fBS. Two cell selection games for distinct scenarios are theoretically modeled to formulate the behaviors of nonsubscribers, and the existences of pure strategy Nash equilibria are also proven under feasible utility functions. From the perspectives of subscribers, HetNet system, and operator, numerical results suggest the adoption of hybrid access mode to provide higher flexibility for the performance enhancement. © 2014 IEEE.

Chi T.S.,National Chiao Tung University
The Journal of the Acoustical Society of America | Year: 2012

Spectro-temporal modulations of speech encode speech structures and speaker characteristics. An algorithm which distinguishes speech from non-speech based on spectro-temporal modulation energies is proposed and evaluated in robust text-independent closed-set speaker identification simulations using the TIMIT and GRID corpora. Simulation results show the proposed method produces much higher speaker identification rates in all signal-to-noise ratio (SNR) conditions than the baseline system using mel-frequency cepstral coefficients. In addition, the proposed method also outperforms the system, which uses auditory-based nonnegative tensor cepstral coefficients [Q. Wu and L. Zhang, "Auditory sparse representation for robust speaker recognition based on tensor structure," EURASIP J. Audio, Speech, Music Process. 2008, 578612 (2008)], in low SNR (≤ 10 dB) conditions.

Hsu C.-C.,National Chiao Tung University
Expert Systems with Applications | Year: 2012

The purpose of this study is to find the key factors influencing blog design, and explore the causal relationships between the criteria for each factor. Since design is a multiple criteria decision-making (MCDM) problem, this study adopts a model which is a hybrid of factor analysis and the Decision Making Trial and Evaluation Laboratory method (DEMATEL). The DEMATEL method is used to simplify and visualize the interrelationships between criteria in making a decision. This study found five core factors that influence blog design: visual clarity, interface and usability, content and searchability, programming, and sociability. In addition, the key criteria for each factor were identified and the impact-relation maps obtained. The results of this study can provide useful guidance to blog designers for developing better blog platforms. © 2011 Elsevier Ltd. All rights reserved.

Lin C.-T.,National Chiao Tung University | Wei C.-C.,National Chi Nan University | Chao M.-I.,National Chiao Tung University
Optics Express | Year: 2011

The dispersion-induced phase noise (PN) in an OFDM RoF system at 60 GHz leads to not only subcarrier phase rotation (PRT) but also intercarrier interference (ICI) to severely degrade the transmission performance, when a commercial cost-effective DFB laser with the linewidth of several MHz is adopted. To mitigate both PRT and ICI, a post PN suppression algorithm is proposed, and it does not require any bandwidth-consuming pilot tone. For a 25.78-Gbps 16-QAM OFDM RoF signal using the laser with 1.8-MHz linewidth, employing the algorithm can extend the maximum transmission distance which corresponds to 3-dBm power penalty at the BER of 2 10-3 from 75 km to more than 115 km, i.e. 50% increment of transmission distance. © 2011 Optical Society of America.

Chao P.C.-P.,National Chiao Tung University
IEEE Sensors Journal | Year: 2011

Recent advances in energy harvesting have been intensified due to urgent needs of portable, wireless electronics with extensive life span. The idea of energy harvesting is applicable to sensors that are placed and operated on some entities for a long time, or embedded into structures or human bodies, in which it is troublesome or detrimental to replace the sensor module batteries. Such sensors are commonly called self-powered sensors. The energy harvester devices are capable of capturing environmental energy and supplanting the battery in a standalone module, or working along with the battery to extend substantially its life. Vibration is considered one of the most high power and efficient among other ambient energy sources, such as solar energy and temperature difference. Piezoelectric and electromagnetic devices are mostly used to convert vibration to ac electric power. For vibratory harvesting, a delicately designed power conditioning circuit is required to store as much as possible of the device-output power into a battery. The design for this power conditioning needs to be consistent with the electric characteristics of the device and battery to achieve maximum power transfer and efficiency. This study offers an overview on various power conditioning electronic circuits designed for vibratory harvester devices and their applications to self-powered sensors. Comparative comments are provided in terms of circuit topology differences, conversion efficiencies and applicability to a sensor module. © 2011 IEEE.

Chien M.-C.,National Chiao Tung University | Tien C.-H.,National Chiao Tung University
Optics Express | Year: 2011

This paper presents a methodology analogous to a general lens design rule to optimize step-by-step the spectral power distribution of a white-light LED cluster with the highest possible color rendering and efficiency in a defined range of color temperatures. By examining a platform composed of four single-color LEDs and a phosphor-converted cool-white (CW) LED, we successfully validate the proposed algorithm and suggest the optimal operation range (correlated color temperature = 2600-8500 K) accompanied by a high color quality scale (CQS > 80 points) as well as high luminous efficiency (97% of cluster's theoretical maximum value). © 2011 Optical Society of America.

Pan J.-W.,National Chiao Tung University | Lin S.-H.,National Chiao Tung University
Optics Express | Year: 2011

We provide a novel achromatic design in the illumination system for a mini projector with an LED light source. The lateral color aberration at the corners of the DMD active area can be reduced to 0.48 μm by our compact ATIR prism. The total prism size is 4091 mm3. The spot sizes at the corner and the edge are also controlled under 198 μm. Moreover, we use a light pipe for color uniformity at the center of the DMD active area. Under the two components for color uniformity, the Δu' v' is well controlled under 0.016 by a 20 mm length of light pipe. The illuminance uniformity at the active area of the DMD chip is higher than 92.8%. The optical efficiency of the light pipe is 94.1%. © 2011 Optical Society of America.

Chow C.W.,National Chiao Tung University | Yeh C.H.,Industrial Technology Research Institute of Taiwan
Optics Express | Year: 2011

Long-reach passive optical network (LR-PON) is considered as a promising technology towards higher capacity and extended coverage optical system. We propose and demonstrate a LR-PON with the capability of Rayleigh backscattering (RB) noise mitigation. By using the upstream signal wavelength-transition generated by a dual-parallel Mach-Zehnder modulator (DP-MZM) based colorless optical networking unit (ONU), the spectral overlap among the upstream signal and the RB noises can be minimized. Hence, due to the achievement of effective RB mitigation, a 100 km LR-PON with a high split-ratio of 512 is demonstrated using 10 Gb/s non-return-to-zero (NRZ) downstream and 2.5 Gb/s NRZ upstream signals. Detail analysis of the wavelength-transition generation is presented. © 2011 Optical Society of America.

Lin Y.-H.,National Chiao Tung University | Chen H.-S.,National Chiao Tung University
Optics Express | Year: 2013

An electrically tunable-focusing and polarizer-free liquid crystal (LC) lens for ophthalmic applications is demonstrated. The optical mechanism of a LC lens used in human eye system is introduced. The polarizer-free LC lens for myopia-presbyopia based on artificial accommodation is demonstrated. The continuously tunable-focusing properties of the LC lenses are more practical in applications for different visional conditions of people. The concept we proposed can also be applied to another types of lenses as long as the focusing properties are tunable. The concept in this paper can also be extensively applied to imaging systems, and projection systems, such as cameras in cell phones, pico projectors, and endoscopes. © 2013 Optical Society of America.

Chang Y.C.,National Chiao Tung University
Journal of the Air & Waste Management Association (1995) | Year: 2012

The mesostructured materials MCM-41 and SBA-15 were studied as possible supports of bromocresol green (BG) dye impregnation for the ammonia gas detection because of their large surface area, high regenerative property, and high thermal stability. X-ray diffraction, transmission electron microscopy, scanning electron microscope, and N2 adsorption analysis were used to characterize the prepared materials. These materials could sense ammonia via visible color change from yellowish-orange to blue color. The color change process of the nanostructured materials was fully reversible during 10 cyclic tests. The results indicated that the ammonia absorption responses of the two nanostructured materials were both very sensitive, and high linear correlation and high precision were achieved. As the gaseous ammonia concentrations were 50 and 5 ppmv, the response times for the SBA-15/BG were only 1 and 5 min, respectively. Moreover the BG dye-impregnated SBA-15 was less affected by the variation in the relative humidity. It also had faster response for the detection of NH3, as well as lower manufacturing price as compared to that of the dye-impregnated MCM-41. Such feature enables SBA-15/BG to be a very promising material for the detection of ammonia gas.

Chen H.-S.,National Chiao Tung University | Lin Y.-H.,National Chiao Tung University
Optics Express | Year: 2013

Conventional endoscopic systems consisting of several solid lenses suffer from a fixed and limited depth-of-field (DOF). For practical applications, conventional endoscopes mechanically change the distance between the solid lenses of a lens module in order to change the focusing plane and DOF to see clearly in a scene. In this paper, we demonstrate an electrically tunable endoscopic system adopting a liquid crystal lens. By means of tunable focusing properties of the LC lens as a positive lens and a negative lens, the object at different objective distances can be imaged to the image sensor clearly and the corresponding depth-of-field can also help to enlarge the total spatial depth perception in a scene. The optical mechanism is discussed. In the experiments, under adjustment of three discrete lens powers of the LC lens, the viewing range or total spatial depth perception of the endoscopic system is from 76.4 mm to 12.4 mm which is 2x improved compared to the conventional one without LC lens. We believe this study can be extended to the applications of industrial and medical endoscopes. © 2013 Optical Society of America.

Teo T.-A.,National Chiao Tung University
International Journal of Remote Sensing | Year: 2013

The object-to-image transformation of high-resolution satellite images often involves a rational functional model (RFM). Traditionally, RFM uses point features to obtain the transformation coefficients. Since control lines offer greater flexibility than control points, this study proposes a new RFM approach based on linear features. The proposed methods include direct RFM and bias-compensated RFM using control lines. The former obtains the rational polynomial coefficients (RPCs) directly from control lines, whereas the latter uses sensor-orientated RPCs and control lines to determine compensated coefficients. The line-based RFMs include vector and parametric line representations. The experiments in this study analysed the effects of line number, orientation, and length using simulation and real data. The real data combined three-dimensional building models and high-resolution satellite images, such as IKONOS and QuickBird images. Experimental results show that the proposed algorithms can achieve pixel-level accuracy. © 2013 Copyright Taylor and Francis Group, LLC.

Wang C.-H.,National Chiao Tung University
International Journal of Production Research | Year: 2015

Diverse customer desires coupled with technological advances have forced companies to manufacture products with ultimate performance, low cost, high quality and much shorter time-to-market. Recently, the popularity of smart phones has given rise to seriously declined product sales of digital cameras. In this paper, a two-phase framework is presented to offer decision supports on developing next-generation cameras. In the phase of market segmentation, Kansei engineering is employed to capture customer perceptions of affective features. Then, rough set theory is conducted to generate decision rules for partitioning the whole market into the consumer segment and the professional segment, respectively. In the phase of product customisation, conjoint analysis is applied to extract customer preferences for functional features. Furthermore, Grey relational analysis is conducted to select the top three varieties with regard to two distinct segments. In particular, this paper is capable to help brand companies or camera manufacturers better capture customer perceptions and preferences for digital cameras, effectively perform market segmentation (based on affective features) and efficiently conduct product customisation (based on functional features). © 2014 Taylor & Francis.

Chang S.-W.,Academia Sinica, Taiwan | Chang S.-W.,National Chiao Tung University
Optics Express | Year: 2011

We develop a frequency-domain formulation in the form of generalized eigenvalue problems for reciprocal microlasers and nanolasers. While the goal is to explore the resonance properties of dispersive cavities, the starting point of our approach is the mode expansion of arbitrary current sources inside the active regions of lasers. Due to the Lorentz reciprocity, a mode orthogonality relation is present and serves as the basis to distinguish various cavity modes. This scheme can also incorporate the asymmetric Fano lineshape into the emission spectra of cavities. We show how to obtain the important parameters of laser cavities based on this formulation. The proposed approach could be an alternative to other computation schemes such as the finite-difference-time- domain method for reciprocal cavities. © 2011 Optical Society of America.

Lee Y.-S.,National Chiao Tung University | Tong L.-I.,National Chiao Tung University
Energy Conversion and Management | Year: 2011

Energy consumption is an important economic index, which reflects the industrial development of a city or a country. Forecasting energy consumption by conventional statistical methods usually requires the making of assumptions such as the normal distribution of energy consumption data or on a large sample size. However, the data collected on energy consumption are often very few or non-normal. Since a grey forecasting model, based on grey theory, can be constructed for at least four data points or ambiguity data, it can be adopted to forecast energy consumption. In some cases, however, a grey forecasting model may yield large forecasting errors. To minimize such errors, this study develops an improved grey forecasting model, which combines residual modification with genetic programming sign estimation. Finally, a real case of Chinese energy consumption is considered to demonstrate the effectiveness of the proposed forecasting model. © 2010 Elsevier Ltd. All rights reserved.

Chen C.-H.,National Chiao Tung University | Liao K.-S.,National Chiao Tung University
Optics Express | Year: 2013

Novel plasmonic power splitters constructed from a rectangular ring resonator with direct-connected input and output waveguides are presented and numerically investigated. An analytical model and systematic approach for obtaining the appropriate design parameters are developed by designing an equivalent lumped circuit model for the transmission lines and applying it to plasmonic waveguides. This approach can dramatically reduce simulation times required for determining the desired locations of the output waveguides. Three examples are shown, the 1 × 3, 1 × 4, and 1 × 5 equal-power splitters, with the design method being easily extended to any number of output ports. © 2013 Optical Society of America.

Lee Y.-S.,National Chiao Tung University | Lin S.-D.,National Chiao Tung University
Optics Express | Year: 2014

We study the polarization properties of quantum dot (QD) emission coupled with the fundamental cavity modes. A rotation of polarization axis and a change of polarization degree are observed as the coupling is varied. To explain this observation, we derive an analytical model considering the polarization misalignment between QD dipole and cavity mode field. Our model also provides a new approach to extract the anisotropic Purcell factors by analyzing the polarization of detected quantum dot emission coupled to the cavity mode, which paves the way to develop high-efficiency polarized single photon sources.©2014 Optical Society of America.

Wang H.-F.,National Chiao Tung University | Wu S.-P.,National Chiao Tung University
Sensors and Actuators, B: Chemical | Year: 2013

A new pyrene derivative (1) containing a benzothiazolenhydrazone moiety exhibited high selectivity for Cu2+ detection. In the presence of Cu2+, chemosensor 1 provided significant fluorescence enhancement, while Ag+, Ca2+, Cd2+, Co2+, Fe 2+, Fe3+, Hg2+, K+, Mg2+, Mn2+, Ni2+, Pb2+, and Zn2+ metal ions produced only minor changes in fluorescence intensity. The association constant (Ka) for Cu2+ binding to 1 had a value of 5.00 × 108 M-2. The maximum fluorescence enhancement induced by Cu2+ binding to the chemosensor was observed over the range pH 2-8.5. Our fluorescence microscopy experiments demonstrate that chemosensor 1 may have application as a fluorescent probe for detecting Cu 2+ in living cells. © 2013 Elsevier B.V.

Hashimoto S.,Tokushima University | Werner D.,Tokushima University | Uwada T.,National Chiao Tung University
Journal of Photochemistry and Photobiology C: Photochemistry Reviews | Year: 2012

This review describes the fundamental aspects of laser-gold nanoparticle (Au NP) interaction that leads to nanoscale energy deposition to the surroundings through light amplification and heat generation. Besides the importance of the primary process in physics and chemistry, application of the light-NP interaction has attracted significant interest from various areas ranging from analytical chemistry to material chemistry and biomedicine. Here we consider both mechanistic and application aspects. Our attention is focused on pulsed-laser-induced fast processes that revealed the heating-cooling dynamics of electrons, lattice (particle), and particle's environment. On the application side, we focus on material fabrication and processing that beat diffraction-limited resolution. Together, we will shed a light on the essence of research activities carried out in the past 10 years. In addition to an abundance of latest information obtained from currently available literature, this review includes figures obtained by our own calculations to provide readers with a better understanding of the basics of the optical properties and energy and heat-transfer processes of Au NPs, which are not familiar to photochemists. © 2012 Elsevier B.V.

Kuo H.-Y.,National Chiao Tung University | Bhattacharya K.,California Institute of Technology
Mechanics of Materials | Year: 2013

We propose a theoretical framework for evaluation of magnetoelectroelastic potentials in a fibrous composite with piezoelectric and piezomagnetic phases, motivated by the technological desire for materials with large magnetoelectric coupling. We show that the problem with transversely isotropic phases can be decomposed into two independent problems, plane strain with transverse electromagnetic fields and anti-plane shear with in-plane electromagnetic fields. We then consider the second problem in detail, and generalize the classic work of Lord Rayleigh (1892) to obtain the electrostatic potential in an ordered conductive composite and its extension to a disordered system by Kuo and Chen (2008) to the current coupled magnetoelectroelastic problem. We use this method to study BaTiO3-CoFe2O4 composites and provide insights into obtaining large effective magnetoelectric coefficient. © 2012 Elsevier Ltd. All rights reserved.

Ko C.-T.,National Chiao Tung University | Chen K.-N.,National Chiao Tung University
Microelectronics Reliability | Year: 2013

3D IC packaging offers miniaturization, high performance, low power dissipation, high density and heterogeneous integration. Through-silicon via (TSV) and bonding technologies are the key technologies of 3D IC, and the corresponding reliability has to be well evaluated and qualified before real production applications. This paper reviews the emerging 3D interconnection technologies in worldwide 3D integration platforms with the latest reliability assessment results, including the reliability demonstration of Cu and oxide hybrid bonding in Ziptronix's platform, micro-bump and adhesive hybrid bonding in ITRI's platform, adhesive bonding followed by TSV formation in WOW alliance's platform, wide I/O interface TSV interposer in Xilinx's platform, and the active and passive TSV interposer in Samsung, TSMC and ASE's platforms. With low temperature bonding and TSV processes, optimized design and material selection to lower the induced stress and warpage, these platforms are successfully developed with enhanced reliability. The reliability of key technologies in 3D integration with these representative platforms are summarized in the paper to address the feasibility of 3D IC in mass production, which could be the guidelines for future development and applications of 3D integration technology. © 2012 Elsevier Ltd. All rights reserved.

Shen I.-S.,National Chiao Tung University | Jou C.F.,National Chiao Tung University
IEEE Transactions on Microwave Theory and Techniques | Year: 2012

This study introduces an X-band quadrature voltage-controlled oscillator (QVCO) based on two novel techniques: capacitor coupling and sinusoidal current biasing. The proposed QVCO achieves an excellent figure-of-merit (FOM) of 190.5 dBc/Hz. This study analyzes the properties of this QVCO, including its phase noise, oscillation frequency, and amplitude. To generate quadrature phase signals with low phase noise, the proposed design uses two capacitor-coupled LC-tank cores instead of active devicecoupled cores. Sinusoidal currents through these capacitors bias the oscillator, increasing oscillation amplitude and reducing the phase noise contribution from cross-coupled transistors compared to existing QVCOs or VCOs biased with a constant current. These two techniques allow the proposed QVCO to achieve at least a theoretical 3 dB phase noise improvement compared to conventional LC-QVCOs. Implemented in a standard 0.18 μm CMOS process, the proposed QVCO had a frequency tuning range of 9.2∼10.4 GHz and a phase noise of -115.7 dBc/Hz@1 MHz from a carrier of 10.4 GHz while consuming 3.6 mW with 1.5 V voltage supply. © 2006 IEEE.

An effective diffusion model characterized by the technology-induced function diversification and cost reductions can be developed to reflect whether competition exists among multiple generations of technology and to interpret how price reductions stimulate consumption. New technology can enhance the production skill levels of LCD TV manufacturing, enabling successive generation of LCD TV to become larger-sized than the previous generation, reducing the overall cost in manufacturing process and resulting in the price reduction of LCD TVs. However, previous diffusive predictions of LCD TVs using conventional multi-generational models ignore the price effect on market potentials and generational substitutions, so a novel generation-specific multi-generational model for the first time incorporating heterogeneous price elasticity and consumer behaviors across various LCD TV sizes is constructed in this work. This study applies nonlinear least square method to simulate the parameters of our modified model and further compares the accuracy between our modified model and the existing models. Analytical results indicate that price reduction strongly correlates with LCD TV sales, implying that price reductions increase the market potential of each LCD TV generation. Our modified model performs superior to the conventional multi-generational model in terms of predicting future shipment orbits of 26-, 42-, and 46-in. LCD TVs. © 2013 Elsevier Ltd. All rights reserved.

Wang C.-H.,National Chiao Tung University | Wang J.,National Chung Hsing University
Applied Soft Computing Journal | Year: 2014

In an era of global customization, dominating the majority market with a single product has become increasingly difficult and almost impossible for most companies. In contrast, they must provide various product varieties that attract diverse customers, particularly when acquiring distinct market segments. In practice, however, most companies cannot effectively reduce the gap between customer requirements and design characteristics, although this impacts the profitability and future growth of companies. Meanwhile, companies often get stuck in the trade-offs between enhancing product varieties and controlling manufacturing costs. Accordingly, this paper proposes a hybrid framework that combines fuzzy analytical hierarchy process (AHP), fuzzy Kano model with zero-one integer programming (ZOIP) to incorporate customer preferences and customer perceptions into the decision-making process of product configuration. Specifically, fuzzy AHP is used to extract customer preferences for core attributes while fuzzy Kano model is utilized to elicit customer perceptions of optional attributes. Finally, by virtue of ZOIP, the optimal product varieties (smart cameras) for distinct segments are determined by maximizing overall customer utility (OCU) and taking a firm's pricing policy into account. © 2014 Elsevier B.V.

Choi H.,University of Notre Dame | Chen W.T.,University of Notre Dame | Chen W.T.,National Chiao Tung University | Kamat P.V.,University of Notre Dame
ACS Nano | Year: 2012

Neighboring metal nanoparticles influence photovoltaic and photocatalytic behavior of semiconductor nanostructures either through Fermi level equilibration by accepting electrons or inducing localized surface plasmon effects. By employing SiO 2- and TiO 2-capped Au nanoparticles we have identified the mechanism with which the performance of dye-sensitized solar cells (DSSC) is influenced by the neighboring metal nanoparticles. The efficiency of an N719 dye-sensitized solar cell (9.3%) increased to 10.2% upon incorporation of 0.7% Au@SiO 2 and to 9.8% upon loading of 0.7% Au@TiO 2 nanoparticles. The plasmonic effect as monitored by introducing Au@SiO 2 in DSSC produces higher photocurrent. However, Au nanoparticles undergo charge equilibration with TiO 2 nanoparticles and shift the apparent Fermi level of the composite to more negative potentials. As a result, Au@TiO 2 nanoparticle-embedded DSSC exhibit higher photovoltage. A better understanding of these two effects is crucial in exploiting the beneficial aspects of metal nanoparticles in photovoltaics. © 2012 American Chemical Society.

Raju M.V.R.,National Chiao Tung University | Lin H.-C.,National Chiao Tung University
Organic Letters | Year: 2013

A novel [2]rotaxane based on an orthogonal H-bonded motif and 3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (DPP) with controlled topicity was successfully constructed, displaying excellent stimulated responses toward anion and solvent polarity. The preorganized host selectively recognized F- with high optical sensitivity and reversibility via enhanced positive cooperativity and noncovalent interaction by evidence of a shorter fluorescence lifetime. © 2013 American Chemical Society.

Rajeshkumar V.,National Chiao Tung University | Lee T.-H.,National Chiao Tung University | Chuang S.-C.,National Chiao Tung University
Organic Letters | Year: 2013

Palladium-catalyzed oxidative carbonylation of N-sulfonyl-2-aminobiaryls through C-H bond activation and C-C, C-N bond formation under TFA-free and milder conditions has been developed. The reaction tolerates a variety of substrates and provides biologically important phenanthridinone derivatives in yields up to 94%. © 2013 American Chemical Society.

Liu S.-R.,National Chiao Tung University | Wu S.-P.,National Chiao Tung University
Organic Letters | Year: 2013

A BODIPY-based fluorescent probe, HCSe, has been successfully developed for the rapid detection of hypochlorous acid based on the specific HOCl-promoted oxidation of diphenyl selenide in response to the amount of HOCl. Confocal fluorescence microscopy imaging using RAW264.7 cells showed that the new probe HCSe could be used as an effective fluorescent probe for detecting HOCl in living cells. © 2013 American Chemical Society.

Lee F.-F.,National Chiao Tung University | Lin G.-L.,National Chiao Tung University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

The deployment of DeepCore array significantly lowers IceCube's energy threshold to about 10 GeV and enhances the sensitivity of detecting neutrinos from annihilations and decays of light dark matter. To match this experimental development, we calculate the track event rate in DeepCore array due to neutrino flux produced by annihilations and decays of galactic dark matter. We also calculate the background event rate due to the atmospheric neutrino flux for evaluating the sensitivity of DeepCore array to galactic dark matter signatures. Unlike previous approaches, which set the energy threshold for track events at around 50 GeV (this choice avoids the necessity of including the oscillation effect in the estimation of atmospheric background event rate), we have set the energy threshold at 10 GeV to take full advantage of DeepCore array. We compare our calculated sensitivity with those obtained by setting the threshold energy at 50 GeV. We conclude that our proposed threshold energy significantly improves the sensitivity of DeepCore array to the dark matter signature for m χ<100GeV in the annihilation scenario and m χ<300GeV in the decay scenario. © 2012 American Physical Society.

Pao H.-T.,National Chiao Tung University | Fu H.-C.,Huaqiao University
Renewable and Sustainable Energy Reviews | Year: 2013

This study employs Brazil's yearly statistics from 1980 to 2010 to explore the causal relationships between the real GDP and four types of energy consumption: non-hydroelectric renewable energy consumption (NHREC), total renewable energy consumption (TREC), non-renewable energy consumption (NREC), and the total primary energy consumption (TEC). The cointegration test reveals a long-run equilibrium among Brazil's real GDP, labour, capital, and each of the four types of consumption. The development of the Brazilian economy has close ties with capital formation and labour force. The influence of NHREC/TREC on real output is positive and significant, while the impacts by NREC/TEC are insignificant. The results from the vector error correction models reveal a unidirectional causality from NHREC to economic growth, a bidirectional causality between economic growth and TREC, and a unidirectional causality from economic growth to NREC or TEC without feedback in the long-run. These findings suggest that Brazil is an energy-independent economy and that economic growth is crucial in providing the necessary resources for sustainable development. Expanding renewable energy would not only enhance Brazil's economic growth and curb the deterioration of the environment but also create an opportunity for a leadership role in the international system and improve Brazil's competition with more developed countries. © 2013 Elsevier Ltd.

Chan P.-H.,National Chiao Tung University | Chen Y.-C.,National Chiao Tung University
Analytical Chemistry | Year: 2012

In this work, human serum albumin (HSA) stabilized gold nanoclusters (HSA-AuNCs) with reddish photoluminescence were used as sensing probes for pathogenic bacteria including Enterobacter cloacae, Escherichia coli J96, Pseudomonas aeruginosa, pandrug-resistant Acinetobacter baumannii (PDRAB), Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Streptococcus pyogenes, and vancomycin-resistant Enterococcus faecalis (VRE). We discovered that HSA-AuNCs have unique affinity with S. aureus and MRSA. In addition to demonstrating the selective sensing ability of HSA-AuNCs toward S. aureus and MRSA, the binding peptide motifs identified from HSA-AuNCs were characterized by mass spectrometry. The identified binding peptides were further used as the reducing and stabilizing agents for generation of peptide-bound AuNCs (Pep-AuNCs). The generated Pep-AuNCs were demonstrated to have the binding affinities with S. aureus and MRSA. © 2012 American Chemical Society.

Chen P.-S.,Indiana University | Chen L.S.,Indiana University | Fishbein M.C.,University of California at Los Angeles | Lin S.-F.,Indiana University | And 2 more authors.
Circulation Research | Year: 2014

Autonomic nervous system activation can induce significant and heterogeneous changes of atrial electrophysiology and induce atrial tachyarrhythmias, including atrial tachycardia and atrial fibrillation (AF). The importance of the autonomic nervous system in atrial arrhythmogenesis is also supported by circadian variation in the incidence of symptomatic AF in humans. Methods that reduce autonomic innervation or outflow have been shown to reduce the incidence of spontaneous or induced atrial arrhythmias, suggesting that neuromodulation may be helpful in controlling AF. In this review, we focus on the relationship between the autonomic nervous system and the pathophysiology of AF and the potential benefit and limitations of neuromodulation in the management of this arrhythmia. We conclude that autonomic nerve activity plays an important role in the initiation and maintenance of AF, and modulating autonomic nerve function may contribute to AF control. Potential therapeutic applications include ganglionated plexus ablation, renal sympathetic denervation, cervical vagal nerve stimulation, baroreflex stimulation, cutaneous stimulation, novel drug approaches, and biological therapies. Although the role of the autonomic nervous system has long been recognized, new science and new technologies promise exciting prospects for the future. © 2014 American Heart Association, Inc.

Peng W.,Michigan State University | Crouse J.C.,Michigan State University | Lin J.-H.,National Chiao Tung University
Health Education and Behavior | Year: 2013

This systematic review evaluates interventions using active video games (AVGs) to increase physical activity and summarizes laboratory studies quantifying intensity of AVG play among children and adults. Databases (Cochrane Library, PsychInfo, PubMed, SPORTDiscus, Web of Science) and forward citation and reference list searches were used to identify peer-reviewed journal articles in English through March 2011. Studies that used off-the-shelf AVGs to increase physical activity with quantitative outcomes or studies that quantified intensity of AVG play were included. Information on sample characteristics, AVGs employed, study design and conditions, outcome measures, results, and conclusions was extracted by two researchers. Intervention studies were ranked on design quality. Thirteen interventions and 28 laboratory studies were identified. All laboratory studies demonstrated that AVGs are capable of providing light-to-moderate intensity physical activity. However, only three interventions supported AVGs as an effective tool to significantly increase physical activity or exercise attendance. As AVGs are becoming more popular, additional research is needed to determine how to capitalize on the potential of AVGs to increase physical activity. © 2012 Society for Public Health Education.

Lin C.-Y.,National Chiao Tung University | Jones B.A.,IBM
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

The engineered spin structures recently built and measured in scanning tunneling microscope experiments are calculated using density functional theory. By determining the precise local structure around the surface impurities, we find that the Mn atoms can form molecular structures with the binding surface, behaving like surface molecular magnets. The spin structures are confirmed to be antiferromagnetic, and the exchange couplings are calculated within 8% of the experimental values simply by collinear-spin generalized gradient approximation +U calculations. We can also explain why the exchange couplings significantly change with different impurity binding sites from the determined local structure. The bond polarity is studied by calculating the atomic charges with and without the Mn adatoms. In addition, we study a second adatom, Co. We study the surface Kondo effect of Co by calculating the surrounding local density of states and the on-site Coulomb Uand compare and contrast the behavior of Co and Mn. Finally, our calculations confirm that the Mn and Co spins of these structures are 5/2 and 3/2, respectively, as also measured indirectly by scanning tunneling microscope. © 2011 American Physical Society.

Lai Y.-Y.,National Chiao Tung University | Lan Y.-P.,National Chiao Tung University | Lu T.-C.,National Chiao Tung University
Light: Science and Applications | Year: 2013

The strong light-matter interaction in ZnO-embedded microcavities has received great attention in recent years, due to its ability to generate the robust bosonic quasiparticles, exciton-polaritons, at or above room temperature. This review introduces the strong coupling effect in ZnO-based microcavities and describes the recent progress in this field. In addition, the report contains a systematic analysis of the room-temperature strong-coupling effects from relaxation to polariton lasing. The stable room temperature operation of polaritonic effects in a ZnO microcavity promises a wide range of practical applications in the future, such as ultra-low power consumption coherent light emitters in the ultraviolet region, polaritonic transport, and other fundamental of quantum optics in solid-state systems. © 2013 CIOMP. All rights reserved.

Lu T.-W.,National Chiao Tung University | Lin P.-T.,National Chiao Tung University | Lee P.-T.,National Chiao Tung University
Optics Letters | Year: 2012

We theoretically propose and investigate a TM-polarized one-dimensional photonic crystal nanocavity with a horizontal SiO2 slot on a suspended silicon nanobeam via the three-dimensional finite-element method. The ultrahigh quality factor and ultrasmall effective mode volume of 1.5 × 107 and 0.176 half-wavelength cubic of the horizontally SiO 2-slotted nanocavity show strong possibilities for realizing an erbium-doped SiO2 nanolaser. This horizontal SiO2 slot structure can be precisely formed via the sputtering process and further transformed into an air slot via selective wet etching for optical index and biomolecule sensing. © 2012 Optical Society of America.

Huang J.-H.,Academia Sinica, Taiwan | Fang J.-H.,Academia Sinica, Taiwan | Liu C.-C.,Academia Sinica, Taiwan | Chu C.-W.,Academia Sinica, Taiwan | Chu C.-W.,National Chiao Tung University
ACS Nano | Year: 2011

In this study, we found that the work functions (Φw) of solution-processable, functional graphene/carbon nanotube-based transparent conductors were readily manipulated, varying between 5.1 and 3.4 eV, depending on the nature of the doping alkali carbonate salt. We used the graphene-based electrodes possessing lower values of Φw as cathodes in inverted-architecture polymer photovoltaic devices to effectively collect electrons, giving rise to an optimal power conversion efficiency of 1.27%. © 2011 American Chemical Society.

Panda D.,National Chiao Tung University | Tseng T.-Y.,National Chiao Tung University
Thin Solid Films | Year: 2013

In the advancement of complementary metal-oxide-semiconductor device technology, SiO2 was used as an outstanding dielectric and has dominated the microelectronics industry for the last few decades. However, with the recent size downscaling, ultrathin SiO2 is no longer suitable. ZrO2 has been introduced as a high-k dielectric to replace SiO 2. This paper reviews recent progress of ZrO2 thin films as dielectric layers for volatile dynamic random access memory (DRAM) applications and as a gate dielectric for CMOS devices. Materials and electrical properties of ZrO2 films obtained by different deposition methods are compared. The effects of different top and bottom electrodes, and different doping elements, on ZrO2 dielectric properties are described. Applications discussed include the use of ZrO2 in Ge and SiGe nanocrystal-embedded nonvolatile flash memory devices. ZrO2 films as charge trapping layers in SOZOS (poly-Si/SiO2/ZrO2/ SiO2/Si) and TAZOS (TaN/Al2O3/ZrO 2/SiO2/Si) based nonvolatile flash memory stacks, and bipolar, unipolar, and nonpolar ZrO2-based resistive switching memory devices are also briefly discussed. The impact of electrode materials, metal nanocrystals, metal implantation, metal doping, metal layers, and oxide ion conductor buffer layer on resistive switching properties and switching parameters of emerging ZrO2-based resistive switching memory devices for high speed, low power, nanoscale, nonvolatile memory devices are briefly reviewed. A roadmap of the applications of ZrO2 thin film in future low power, nanoscale microelectronic device applications is realized from this review. © 2013 Elsevier B.V.

Lin C.-P.,National Chiao Tung University
Electronic Commerce Research and Applications | Year: 2011

This study validates a research model that examines usage of instant messaging (IM) from the aspect of online social support. Drawing on the social capital theory, this study postulates that IM usage is indirectly affected by social support via the mediation of the following six dimensions of social capital: commitment, reciprocity, shared codes and language, shared narratives, centrality, and network ties. The model tests data obtained from business organizations in Taiwan, and the results suggest that the indirect influence of social support on IM usage through shared codes and language is significant, and the indirect influence of social support on IM usage through centrality is also significant. Managerial implications and limitations of the empirical findings are provided. © 2010 Elsevier B.V. All rights reserved.

Yang C.-H.,National Chiao Tung University | Yu T.-H.,University of California at Los Angeles | Markoviae D.,University of California at Los Angeles
IEEE Journal of Solid-State Circuits | Year: 2012

This paper presents a design methodology for power and area minimization of flexible FFT processors. The methodology is based on the power-area tradeoff space obtained by adjusting algorithm, architecture, and circuit variables. Radix factorization is the main technique for achieving high energy efficiency with flexibility, followed by architecture parallelism and delay line circuits. The flexibility is provided by reconfigurable processing units that support radix-2/4/8/16 factorizations. As a proof of concept, a 128- to 2048-point FFT processor for 3GPP-LTE standard has been implemented in a 65-nm CMOS process. The processor designed forminimum power-area product is integrated in 1.25 × 1.1 mm 2 and dissipates 4.05 mW at 0.45 V for the 20 MHz LTE bandwidth. The energy dissipation ranging from 2.5 to 103.7 nJ/FFT for 128 to 2048 points makes it the lowest energy flexible FFT. © 2012 IEEE.

Chen P.-W.,National Chiao Tung University | Chen F.-C.,National Chiao Tung University
IEEE Antennas and Wireless Propagation Letters | Year: 2012

A novel low-profile zeroth-order (ZOR) antenna is presented. The feature of ZOR based on periodic structures is employed to reduce the antenna size, while these antennas generally suffer from narrow bandwidth. A single-layer asymmetric coplanar waveguide (ACPW) structure is proposed to realize a bandwidth-extended ZOR antenna, where the antenna bandwidth is characterized by an equivalent circuit model. The ACPW structure not only provides the design freedom, but also overcomes the design constraint of the traditional CPW. The ACPW ZOR antenna is verified by both full-wave simulations and experiments. As an advantage of the proposed method, the size of antenna is reduced, and the resonant frequency of zeroth-order mode is 1.94 GHz with radiation efficiency of 85%, measured 10-dB fractional bandwidth up to 10.3%, and omnidirectional peak gain of 2.3 dBi. © 2012 IEEE.

Tsai C.-C.,National Chiao Tung University | Chen J.-T.,National Chiao Tung University
Langmuir | Year: 2014

We study the Rayleigh instability of polystyrene (PS) thin films coated in the nanopores of anodic aluminum oxide (AAO) templates. After thermal annealing, the surface of the PS thin films undulates and the nanostructures transform from nanotubes to Rayleigh-instability-induced nanostructures (short nanorods with encapsulated air bubbles). With longer annealing times, the nanostructures further transform to nanorods with longer lengths. PS samples with two different molecular weights (24 and 100 kg/mol) are used, and their instability transformation processes are compared. The morphology diagrams of the nanostructures at different stages are also constructed to elucidate the mechanism of the morphology transformation. © 2013 American Chemical Society.

Chen M.-Y.,National Chiao Tung University | Hsu Y.-J.,National Chiao Tung University
Nanoscale | Year: 2013

A novel one-step cation exchange approach has been developed to prepare ZnO-decorated ZnSe nanorods (ZnSe-ZnO NRs), a prototype type-II semiconductor nanoheterostructure. Because of the staggered band offset which promoted effective charge separation, the as-synthesized ZnSe-ZnO NRs exhibited remarkable photocatalytic activities under visible light illumination, demonstrating their promising potentials in relevant photoconversion applications. © 2013 The Royal Society of Chemistry.

Hsiao Y.-C.,National Taiwan University | Lee W.,National Chiao Tung University
Optics Express | Year: 2013

Dual-frequency cholesteric liquid crystal (DFCLC) devices characteristically require high operation voltage, which hinders their further development in thin-film-transistor driving. Here we report on a lowervoltage switching method based on the thermodielectric effect. This technique entails applying a high-frequency voltage to occasion dielectric oscillation heating so to induce the increase in crossover frequency. The subsequent change in dielectric anisotropy of the DFCLC allows the switching, with a lower operation voltage, from the planar state to the focal conic or homeotropic state. The temperature rise incurred by the dielectric heating is described. © 2013 Optical Society of America.

McDonald M.J.,Academia Sinica, Taiwan | Wang W.-C.,National Chiao Tung University | Huang H.-D.,National Chiao Tung University | Leu J.-Y.,Academia Sinica, Taiwan
PLoS Biology | Year: 2011

The genome-sequencing gold rush has facilitated the use of comparative genomics to uncover patterns of genome evolution, although their causal mechanisms remain elusive. One such trend, ubiquitous to prokarya and eukarya, is the association of insertion/deletion mutations (indels) with increases in the nucleotide substitution rate extending over hundreds of base pairs. The prevailing hypothesis is that indels are themselves mutagenic agents. Here, we employ population genomics data from Escherichia coli, Saccharomyces paradoxus, and Drosophila to provide evidence suggesting that it is not the indels per se but the sequence in which indels occur that causes the accumulation of nucleotide substitutions. We found that about two-thirds of indels are closely associated with repeat sequences and that repeat sequence abundance could be used to identify regions of elevated sequence diversity, independently of indels. Moreover, the mutational signature of indel-proximal nucleotide substitutions matches that of error-prone DNA polymerases. We propose that repeat sequences promote an increased probability of replication fork arrest, causing the persistent recruitment of error-prone DNA polymerases to specific sequence regions over evolutionary time scales. Experimental measures of the mutation rates of engineered DNA sequences and analyses of experimentally obtained collections of spontaneous mutations provide molecular evidence supporting our hypothesis. This study uncovers a new role for repeat sequences in genome evolution and provides an explanation of how fine-scale sequence contextual effects influence mutation rates and thereby evolution. © 2011 McDonald et al.

Cheng Y.-J.,National Chiao Tung University | Hsieh C.-H.,National Chiao Tung University | He Y.,CAS Beijing National Laboratory for Molecular | Hsu C.-S.,National Chiao Tung University | Li Y.,CAS Beijing National Laboratory for Molecular
Journal of the American Chemical Society | Year: 2010

A poly(3-hexylthiophene) (P3HT)-based inverted solar cell using indene-C60 bis-adduct (ICBA) as the acceptor achieved a high open-circuit voltage of 0.82 V due to ICBA's higher-lying lowest unoccupied molecular orbital level, leading to an exceptional power-conversion efficiency (PCE) of 4.8%. By incorporating a cross-linked fullerene interlayer, C-PCBSD, to further modulate the interface characteristics, the ICBA:P3HT-based inverted device exhibited an improved short-circuit current and fill factor, yielding a record high PCE of 6.2%. © 2010 American Chemical Society.

Wang T.,National Chiao Tung University
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2011

Cluster ensembles have attracted a lot of research interests in recent years, and their applications continue to expand. Among the various algorithms for cluster ensembles, those based on coassociation matrices are probably the ones studied and used the most because coassociation matrices are easy to understand and implement. However, the main limitation of coassociation matrices as the data structure for combining multiple clusterings is the complexity that is at least quadratic to the number of patterns N. In this paper, we propose CA-tree, which is a dendogram-like hierarchical data structure, to facilitate efficient and scalable cluster ensembles for coassociation-matrix-based algorithms. All the properties of the CA-tree are derived from base cluster labels and do not require the access to the original data features. We then apply a threshold to the CA-tree to obtain a set of nodes, which are then used in place of the original patterns for ensemble-clustering algorithms. The experiments demonstrate that the complexity for coassociation-based cluster ensembles can be reduced to close to linear to N with minimal loss on clustering accuracy. © 2010 IEEE.

Gau R.-H.,National Chiao Tung University
IEEE Transactions on Wireless Communications | Year: 2011

In this paper, we propose the tree/stack splitting with remainder algorithm for distributed medium access control in a wireless network with multipacket reception. In order to reduce the length of a cycle and increase the network throughput, when the splitting with remainder algorithm is used, some nodes that attempt to transmit packets at the beginning of a cycle might have to postpone their packet retransmissions until the beginning of the next cycle. We demonstrate that the splitting with remainder algorithm outperforms the erasure algorithm and the probe algorithm. For the splitting with remainder algorithm, we analytically and accurately derive the network throughput and the average packet delay. We show that our analytical results are consistent with packet-based simulation results. © 2006 IEEE.

Li S.-Y.,National Chiao Tung University | Ge Z.-M.,National Chiao Tung University
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2011

In this paper, a new fuzzy model is presented to simulate and synchronize two totally different and complicated chaotic systems, namely, 1) quantum cellular neural networks nanosystem (Quantum-CNN system) and 2) Qi system. Through the new fuzzy model, the following three main advantages can be obtained: 1) only two linear subsystems are needed; 2) the numbers of fuzzy rules can be reduced from 2 N to 2 × N (comparing with the Takagi-Sugeno fuzzy model), where N is the number of nonlinear terms; 3) fuzzy synchronization of two different chaotic systems with different numbers of nonlinear terms can be achieved with only two sets of gain K. There are two examples in numerical simulation results to show the effectiveness and feasibility of our new model. © 2011 IEEE.

Sung Y.-M.,National Chiao Tung University | Wu S.-P.,National Chiao Tung University
Sensors and Actuators, B: Chemical | Year: 2014

A sensitive and selective colorimetric Cd2+ detection method was developed using di-(1H-pyrrol-2-yl)methanethione functionalized gold nanoparticles (DP-AuNPs). Aggregation of DP-AuNPs was induced immediately in the presence of Cd2+, yielding a color change from red to blue. This Cd2+-induced aggregation of DP-AuNPs was monitored using the naked eye and UV-vis spectroscopy. The SPR absorbance (635 nm) of the reaction between DP-AuNPs and Cd2+ shows a good linearity in the Cd2+ concentration range of 0.5-16 μM and a low detection limit 16.6 nM (S/N = 3). The DP-AuNPs showed excellent selectivity toward Cd2+ compared to other metal ions Ag+, Al3+, Ca2+, Cd 2+, Co2+, Cr3+, Cu2+, Fe 2+, Fe3+, Hg2+, Mg2+, Mn 2+, Ni2+, Pb2+, and Zn2+. Optimal detection of Cd2+ was achieved over a pH range from 4 to 9.5. Furthermore, DP-AuNPs were applied to detect Cd2+ in lake water, showing low interference. © 2014 Elsevier B.V. All rights reserved.

Sung Y.-M.,National Chiao Tung University | Wu S.-P.,National Chiao Tung University
Sensors and Actuators, B: Chemical | Year: 2014

A sensitive and selective colorimetric Ag+ detection method was developed by using N-1-(2-mercaptoethyl)adenine functionalized gold nanoparticles (MEA-AuNPs). The presence of Ag+ immediately induced aggregation of MEA-AuNPs, yielding a color change from red to blue. This Ag +-induced aggregation of MEA-AuNPs was monitored by bare eye and UV-vis spectroscopy with a detection limit of 3.3 nM. MEA-AuNPs showed excellent selectivity toward Ag+ compared with other metal ions through interaction between adenine and Ag+. The best detection of Ag + was achieved at pH 6-9. Furthermore, MEA-AuNPs were applied to detect Ag+ in lake water with low interference. © 2014 Elsevier B.V.

Yu S.-Y.,National Chiao Tung University | Wu S.-P.,National Chiao Tung University
Sensors and Actuators, B: Chemical | Year: 2014

A new coumarin derivative (MS1) containing an imine moiety and a hydroxyl moiety exhibits an enhanced fluorescence in the presence of Hg2+ ions. Other metal ions Al3+, Ca2+, Co2+, Cr3+, Cu2+, Fe2+, Fe3+, Hg 2+, K+, Mg2+, Mn2+, Ni2+, Pb2+, and Zn2+ produced only minor changes in the fluorescence values of MS1. The binding ratio of MS1-Hg2+ complexes was determined from the Job plot to be 1:1. The binding constant (Ka) of Hg2+ binding to MS1 was found to be 6.85 × 103 M-1. The maximum fluorescence enhancement caused by Hg2+ binding to MS1 was observed in the pH range of 6.5-9.0. Confocal fluorescence microscopy imaging using RAW 264.7 cells showed that MS1 could be used as an effective fluorescent probe for detecting Hg2+ in living cells. © 2014 Elsevier B.V. All rights reserved.

Laird D.A.,Iowa State University | Chang C.-W.,National Chiao Tung University
Soil and Tillage Research | Year: 2013

Here we evaluate the impact of 19 years of either zero or approximately 90% removal of above ground crop residue on soil quality. The 0-5, 5-15, and 15-30. cm soil depths of Waukegan silt loam (Typic Hapludoll) from east-central Minnesota were sampled from plots after 12 and 7 years of maize and soybean cropping, respectively. On average for the 0-5 and 5-15. cm depths, soil organic C was 12% less, total N was 12.6% less, N mineralization potential was 27.7% less, cation exchange capacity was 7.3% less, macro aggregation was 13.0% less, and total respiration was 12.3% less for plots with residue harvesting relative to plots where residue was not harvested. Minimal impacts of residue harvesting were apparent for the 15-30. cm soil samples, except N mineralization potential which was 28% lower for plots with residue harvesting. Declines in soil quality indicators due to residue harvesting were only slightly less severe for no-tillage plots relative to chisel and moldboard plow tillage plots. We conclude that harvesting 90% of above ground residue for 19 years resulted in substantial degradation of soil quality, and that the impact on N mineralization potential was substantially larger than the loss of total N, suggesting that labile organic N was selectively depleted. We also conclude that stover harvesting for bioenergy production could cause similar degradation of soil quality unless management practices that increase C inputs to soils are also implemented. © 2013 Elsevier B.V.

Bessho T.,Ecole Polytechnique Federale de Lausanne | Zakeeruddin S.M.,Ecole Polytechnique Federale de Lausanne | Yeh C.-Y.,National Chung Hsing University | Diau E.W.-G.,National Chiao Tung University | Gratzel M.,Ecole Polytechnique Federale de Lausanne
Angewandte Chemie - International Edition | Year: 2010

To dye for: A porphyrin chromophore, which is integrated into a donor-acceptor dye as a π-conjugated bridge (see picture), exhibits an unprecedented efficiency of 11 □ % when used as a photosensitizer in a double-layer TiO2 film. A greatly enhanced photovoltaic performance is observed when the porphyrin dye is cosensitized with a metal-free dye that has a complementary spectral response. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lin L.-Y.,National Chiao Tung University | Bai H.,National Chiao Tung University
Applied Catalysis B: Environmental | Year: 2014

A series of bimetallic Ce/Al catalysts supported on mesoporous silica catalysts were prepared through fast salt-templated aerosol process in this study. The source of sodium silicate precursor was from the alkali-extraction of the opto-electronic industrial waste. The inorganic salt formed during the silicate acidification process was served as an effective and low-cost template, which could be simply removed by water washing at room temperature. The Ce/Al-SiO2 catalysts were fabricated under various aerosol-spraying temperatures, and the temperature effects on the structural and surface properties were investigated by XRD, nitrogen physisorption measurement, SEM/TEM, ICP-MS, 27Al MAS-NMR, UV-vis spectra, H2-TPR and NH3-TPD analyses. The catalytic behavior was further evaluated in terms of acetone oxidation. The results revealed that the catalytic oxidation of acetone is mainly governed by the surface redox property, along with the acidity of the catalysts. The Ce/Al-SiO2-300, with high surface acidity and strong surface reducibility, appeared to have the best acetone catalytic performance at temperatures of 100-300°C and its T90 was at 165°C under acetone inlet concentration of 1000ppmv and GHSV of 15,000h-1. Furthermore, compared with literature data which catalysts were prepared using commercial silicon source and traditional organic surfactant templates, Ce/Al-SiO2-300 showed a comparable catalytic performance, indicating the great potential application of Ce/Al-SiO2 catalysts for the catalytic oxidation of acetone. © 2013 Elsevier B.V.

Hsiao Y.-C.,National Chiao Tung University | Lee W.,National Chiao Tung University
Optics Letters | Year: 2015

Cholesteric liquid-crystalline materials are abundant in nature such as condensed phases of DNA, plant cell walls, and chiral biopolymers. These self-organized helical structures produce unique optical properties, giving rise to the selective Bragg reflection of colorful light. In this Letter, we focus on the focal conic state of cholesteric liquid crystals and report on stable, tunable, and reversible color switching among red, green, and blue in polymer-stabilized cholesteric films. The experimental results indicate that, with appropriate voltage pulses, the electrically induced color switching of all six routes can be realized in a single cell reflecting green light. The scattered transmissive color persists at zero voltage due to the polymer stabilization. © 2015 Optical Society of America.

Chen S.-K.,National Chiao Tung University
Computers in Human Behavior | Year: 2012

Studies of correlations between Internet use and psychological well-being (PW) have produced mixed results. The present study used a latent profile analysis to distinguish among populations in terms of PW profiles, and then used a multinomial logistic regression to determine how online entertainment, social use, problematic Internet use (PIU), and gender predicted each latent PW profile. The initial sample consisted of 757 Taiwanese college freshmen. Four ordered latent groups were established as follows: good PW, normative, minor-disadvantageous, and severe-disadvantageous. No latent PW profile stability was found in subsequent years: three groups (normative, minor-disadvantageous and severe-disadvantageous) emerged in Year 2, and only one group emerged in Year 3. The results indicate (a) no relationship between PW and online entertainment or gender, (b) greater PIU increased the likelihood of disadvantageous PW and decreased the probability of good PW, and (c) greater use of online resources for social purposes was related to increased probability of a participant being in the good PW group, but not associated with fewer PW problems. © 2012 Elsevier Ltd. All rights reserved.

Rosenstein B.,National Chiao Tung University | Rosenstein B.,Ariel University | Lewkowicz M.,Ariel University
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

The response to an electric field (dc and ac) of electronic systems in which the Fermi "surface" consists of a number of three-dimensional (3D) Weyl points (such as some pyrochlore iridates) exhibits a peculiar combination of characteristics usually associated with insulating and conducting behavior. Generically a neutral plasma in clean materials can be described by a tight-binding model with a strong spin-orbit interaction. A system of that type has a vanishing dc conductivity; however the current response to the dc field is very slow: The current decays with time in a powerwise manner, different from an insulator. The ac conductivity, in addition to a finite real part σ′(Ω) which is linear in frequency, exhibits an imaginary part σ′′(Ω) that increases logarithmically as a function of the UV cutoff (atomic scale). This leads to a substantial dielectric response like a large dielectric constant at low frequencies. This is in contrast to a two-dimensional (2D) Weyl semimetal-like graphene at a neutrality point where the ac conductivity is purely pseudodissipative. The Coulomb interaction between electrons is long range and sufficiently strong to make a significant impact on transport. The interaction contribution to the ac conductivity is calculated within the tight-binding model. The result for the real part expressed via the renormalized (at frequency Ω̄) Fermi velocity v is Δσ ′(Ω)=e4Ω/(9π2âv)[2log(Ω/ Ω̄)-5]. © 2013 American Physical Society.

Chiu S.-P.,National Chiao Tung University | Lin J.-J.,National Chiao Tung University
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

We have studied the carrier transport in two topological insulator (TI) Bi2Te3 microflakes between 0.3 and 10 K and under applied backgate voltages (VBG). Logarithmic temperature dependent resistance corrections due to the two-dimensional electron-electron interaction effect in the presence of weak disorder were observed. The extracted Coulomb screening parameter is negative, which is in accord with the situation of strong spin-orbit scattering as is inherited in the TI materials. In particular, positive magnetoresistances (MRs) in the two-dimensional weak-antilocalization (WAL) effect were measured in low magnetic fields, which can be satisfactorily described by a multichannel-conduction model. Both at low temperatures of T<1 K and under high positive VBG, signatures of the presence of two coherent conduction channels were observed, as indicated by an increase by a factor of ≈2 in the prefactor which characterizes the WAL MR magnitude. Our results are discussed in terms of the (likely) existence of the Dirac fermion surface states, in addition to the bulk states, in the three-dimensional TI Bi2Te3 material. © 2013 American Physical Society.

Yeh H.-D.,National Chiao Tung University | Chang Y.-C.,National Chiao Tung University | Chang Y.-C.,Taiwan Typhoon and Flood Research Institute
Advances in Water Resources | Year: 2013

Well hydraulics is a discipline to understand the process of flow to the well in an aquifer which is regarded as a source of groundwater. A variety of analytical and numerical models have been developed over the last few decades to provide a framework for understanding and quantifying the flow behavior in aquifer systems. In this review, we first briefly introduce the background of the theory of well hydraulics and the concepts, methodologies, and applications of analytical, semi-analytical, numerical and approximate methods in solving the well-hydraulic problems. We then address the subjects of current interests such as the incorporation of effects of finite well radius, wellbore storage, well partial penetration, and the presence of skin into various practical problems of groundwater flow. Furthermore, we also summarize recent developments of flow modeling such as the flow in aquifers with horizontal wells or collector wells, the capture zone delineation, and the non-Darcian flow in porous media and fractured formations. Finally, we present a comprehensive review on the numerical calculations for five well functions frequently appearing in well-hydraulic literature and suggest some topics in groundwater flow for future research. © 2012 Elsevier Ltd.

Pu Y.-C.,National Chiao Tung University | Hsu Y.-J.,National Chiao Tung University
Nanoscale | Year: 2014

We developed a single-step hot-injection process to synthesize Cd 1-xZnxSe quantum dots (QDs) with tunable emission wavelengths. The multiple emission colors of the Cd1-xZn xSe QDs resulted from the variation in their compositions (x value) with the reaction time. Because of the higher reactivity of the Cd precursor, QDs whose composition was rich in CdSe were generated at