NTHU

Hsinchu, Taiwan
Hsinchu, Taiwan
SEARCH FILTERS
Time filter
Source Type

Kung P.-J.,NTHU | Lee A.-P.,High Brightness Injector Group | Leou K.-C.,NTHU | Lau W.-K.,High Brightness Injector Group
IPAC 2016 - Proceedings of the 7th International Particle Accelerator Conference | Year: 2016

Beam position monitors (BPM) have been widely used on linear colliders and free electron lasers for beam-based alignment and feedback systems. A laser driven photoinjector system has been constructed in NSRRC. This injector has the capability to deliver short relativistic electron beam at high peak current for novel light source R&D. A 2.5 GHz, BPM that can be used for high precision beam position measurement has been designed. The BPM were modified to separate frequency between the horizontal and vertical dipole signals, as well as a reduction of the monopole signal. The design has been simulated by CST. A prototype has been built for verification of theoretical predictions. Microwave bench measurement has been made to compare with the computer simulation results. The progress of our work will be presented in this paper. Copyright © 2016 CC-BY-3.0 and by the respective authors.


Chao A.,SLAC | Granados E.,SLAC | Huang X.,SLAC | Ratner D.,SLAC | Luo H.-W.,NTHU
IPAC 2016 - Proceedings of the 7th International Particle Accelerator Conference | Year: 2016

The mechanism of steady-state microbunching (SSMB) was proposed for providing high power coherent radiation using electron storage rings. The mechanism follows closely the RF bunching in conventional storage rings, with the RF system at a microwave wavelength replaced by a seeded laser in an undulator at an optical wavelength. No FEL mechanism, and thus no FEL energy heating, is invoked. The basic idea is firstly to make the beam microbunched so that its radiation becomes coherent, and secondly to make the microbunching a steady state so that the coherent radiation is maintained at every turn. The combination of the high repetition rate of a storage ring and the enhanced radiation power by a factor of Ncoh (the number of electrons in the microbunches within one coherence length) opens the possibility as well as challenges of very high power SSMB sources. To explore its potential reach, we apply SSMB to the infrared, deep ultraviolet and EUV regions and estimate their respective power levels. Several variants of the SSMB schemes are discussed. A proof-of-principle configuration without an identified testbed is also suggested. Copyright © 2016 CC-BY-3.0 and by the respective authors.


Hsu H.-L.,National Taiwan University | Teng L.-J.,National Chiao Tung University | Chen Y.-C.,Institute of Electronics Engineering | Hsu W.-L.,NTHU | And 6 more authors.
Advanced Materials | Year: 2010

Carbon nanotubes were grown on flexible polylmide substrates at temperatures below 400°C as electrodes for extracellularly neuronal recording. The electrical charge-transfer and electrochemical properties of such CNT electrodes were enhanced by UV-ozone exposure, which induced the formation of C-O, C=O, and O-C=O bonds and reduced the CNT/ electrolyte Interfacial Impedance while increasing the interfacial capacitance. Figure presented © 2010 WILEY-VCH Verlag GmbH & Co. KGaA.


Chen Y.-C.,National Tsing Hua University | Hsu H.-L.,NTHU | Lee Y.-T.,Institute of NanoEngineering and MicroSystems | Su H.-C.,NTHU | And 8 more authors.
Journal of Neural Engineering | Year: 2011

A variety of microelectrode arrays (MEAs) has been developed for monitoring intra-cortical neural activity at a high spatio-temporal resolution, opening a promising future for brain research and neural prostheses. However, most MEAs are based on metal electrodes on rigid substrates, and the intra-cortical implantation normally causes neural damage and immune responses that impede long-term recordings. This communication presents a flexible, carbon-nanotube MEA (CMEA) with integrated circuitry. The flexibility allows the electrodes to fit on the irregular surface of the brain to record electrocorticograms in a less invasive way. Carbon nanotubes (CNTs) further improve both the electrode impedance and the charge-transfer capacity by more than six times. Moreover, the CNTs are grown on the polyimide substrate directly to improve the adhesion to the substrate. With the integrated recording circuitry, the flexible CMEA is proved capable of recording the neural activity of crayfish in vitro, as well as the electrocorticogram of a rat cortex in vivo, with an improved signal-to-noise ratio. Therefore, the proposed CMEA can be employed as a less-invasive, biocompatible and reliable neuro-electronic interface for long-term usage. © 2011 IOP Publishing Ltd.


Huang C.W.,NTHU | Lee S.-Y.,IUCEEM | Hwang C.-S.,NSRRC
IPAC 2014: Proceedings of the 5th International Particle Accelerator Conference | Year: 2014

Robinson wiggler is a special insertion device that can be used to decrease natural emittance of the Taiwan Photon Source (TPS) storage ring. This Robinson wiggler can change damping partition number and then affect the emittance. This study will evaluate practicability of reducing the emittance of TPS storage ring by Multi-period Robinson Wiggler (MRW) in the 7 m long straight section. One period of the traditional Robinson Wiggler include four poles with different field polarity. In the same length, the multi-period Robinson Wiggler has been over four poles in one set of Robinson Wiggler that is different from the traditional Robinson wiggler. Due to the traditional Robinson wiggler cannot be effective to improve emittance in TPS storage ring (the efficiency is only 7% with 6 straight sections). So we adopt to use multi-period Robinson Wiggler, the efficiency can be up to 30% with 6 straight sections, and the linear matching result is better than traditional Robinson Wiggler. Copyright © 2014 CC-BY-3.0 and by the respective authors.


Shih P.-C.,NTHU | Huang K.-C.,NTCU | Lee C.-R.,NTHU | Chung I.-H.,IBM | Chung Y.-C.,NTHU
Proceedings - 11th IEEE/ACM International Symposium on Cluster, Cloud and Grid Computing, CCGrid 2011 | Year: 2011

This paper proposes a processor allocation technique named temporal look-ahead processor allocation (TLPA) that makes allocation decision by evaluating the allocation effects on subsequent jobs in the waiting queue. TLPA has two strengths. First, it takes multiple performance factors into account when making allocation decision. Second, it can be used to optimize different performance metrics. To evaluate the performance of TLPA, we compare TLPA with best-fit and fastest-first algorithms. Simulation results show that TLPA has up to 32.75 performance improvement over conventional processor allocation algorithms in terms of average turnaround time in various system configurations. © 2011 IEEE.


Wu Y.-C.,NTHU | Lin Y.-R.,NTHU | Chiang Y.-W.,NTHU | Wang W.-C.,NTHU
ASME 2016 Conference on Information Storage and Processing Systems, ISPS 2016 | Year: 2016

This work presents the structure Junctionless FinFET(JLFinFET) based on ultra-thin body (UTB) with double stacked Si3N4 charge trapping layer (NN-CTL) Si-SiO2-Si3N4-Si3N4-SiO2-Si (SONNOS) nonvolatile memory (NVM). The device shows excellent transistor performances including steep subthreshold swing (SS) of 76 mV/dec, favorable Vth, and high Ion/Ioff ratio (>107). For n-channel device, it shows excellent memory characteristics, high program/erase (P/E) performance, good endurance (>104 cycles) and an excellent 95-99% electron retention at 85°C for 10 years. © Copyright 2016 by ASME.


Yen S.-J.,National Tsing Hua University | Hsu W.-L.,NTHU | Chen Y.-C.,Institute of Electronics Engineering | Su H.-C.,National Tsing Hua University | And 4 more authors.
Biosensors and Bioelectronics | Year: 2011

This paper reports the success of amino-functionalization on multi-walled carbon nanotubes (MWCNTs) to promote neuronal cells growth on MWCNT electrode for extracellular recording, attributed to the formation of positive charge of NH2 molecules on their surfaces. Besides, the surface of MWCNT electrode becomes hydrophilic after amino-functionalization (AF-MWCNTs) which can enhance electrical conductivity because of lower MWCNT/electrolyte interfacial impedance and higher interfacial capacitance. Durability tests show that electrical characteristics of the MWCNTs treated by 2wt% 1,4-diaminobutane solution (2wt%-AF-MWCNTs) can last for at least six months in air ambient. The neural recording of crayfish shows that 2wt%-AF-MWCNTs can provide better capability on detecting action potentials of caudal photoreceptor (CPR) interneuron compared to suction glass pipette from the evidence of a higher S/N ratio (126 versus 23). The amino-functionalized MWCNT electrode is feasible for long-term recording application according to the results of biocompatibility tests. As the MWCNTs were directly synthesized on Si-based substrates by catalyst-assisted thermal chemical vapor deposition (CVD) at a low temperature (400°C), these self-aligned MWCNT electrodes could be friendly implemented in integrated circuits fabrications. © 2011.


Hsu Y.C.,NTHU | Sheu R.J.,NTHU
11th International Topical Meeting on Nuclear Applications of Accelerators, AccApp 2013 | Year: 2013

This study intends to predict the scope of neutron production and induced radioactivity for two therapy accelerators in Taiwan: 235 MeV proton and 400 MeV/A carbon ion accelerators. For radiation safety concern, much effort has been put into associated benchmark calculations to ensure the quality of predictions. Two Monte Carlo codes FLUKA and MCNPX were applied to calculate the neutron yield from beam bombardment. In addition, FLUKA was used to study the target activation by examining isotope inventory, residual activity, remnant dose rate, and their time behaviour. The calculated results were compared with experimental data published in literature. For the proton-induced neutron yield, FLUKA and MCNPX both well reproduce the measured results over the entire neutron energy range and for various emission angles. For the carbon-induced neutron yield, there exist larger discrepancies between calculations and measurements. Regarding activation related calculations, a factor of two or larger differences between calculations and measurements were observed due to some limitations of underlying nuclear models and uncertainties involved in comparisons. For practical considerations in radiation safety, this study can give us guidance and confidence in using these codes for shielding design and activation analysis of particle therapy accelerators.


Sathiaraj G.D.,Indian Institute of Technology Hyderabad | Lee C.,NTHU | Tsai C.W.,NTHU | Yeh J.W.,NTHU | Bhattacharjee P.P.,Indian Institute of Technology Hyderabad
IOP Conference Series: Materials Science and Engineering | Year: 2015

An equiatomic FCC CoCrFeMnNi high entropy alloy (HEA) was heavily cold rolled up to 90% reduction in thickness followed by isochronal annealing for 1 hour at temperatures ranging between 700°C to 1100°C. A strong brass texture was observed in the cold-rolled condition indicating the low stacking fault energy of the material. A fine stable microstructure was observed during annealing at low temperatures. The recrystallization texture was characterized by the presence of deformation texture components, in particular, the α-fiber (ND//<110>), S ({123} <634>) and the typical brass recrystallization texture component ({236} <385>). Annealing twins were shown to have important effect on the formation of annealing texture. © Published under licence by IOP Publishing Ltd.

Loading NTHU collaborators
Loading NTHU collaborators