Nanjing, China

Nanjing University of Science and Technology or NUST is one of the national key universities under the Ministry of Industry and Information Technology of China. The university was derived from the Institute of Military Engineering of the PLA, which was the highest institution of military technology in China established in 1953. The institute was successively called Artillery Engineering Institute, Engineering Institute of Eastern China, and East China Institute of Technology, and finally to its current name in 1993. It is a science-oriented university located in Xuanwu District in the east suburban area of Nanjing, China. The university places emphasis on both education and research, and is listed in the national 211 Project. The main campus is located in 200 Xiaolingwei, Xuanwu district, Nanjing, Jiangsu Province, China. Wikipedia.


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Li J.,Nanjing University of Science and Technology | Li J.,Utah State University | Ren W.,University of California at Riverside | Xu S.,Nanjing University of Science and Technology
IEEE Transactions on Automatic Control | Year: 2012

This note studies the distributed containment control problem for a group of autonomous vehicles modeled by double-integrator dynamics with multiple dynamic leaders. The objective is to drive the followers into the convex hull spanned by the dynamic leaders under the constraints that the velocities and the accelerations of both the leaders and the followers are not available, the leaders are neighbors of only a subset of the followers, and the followers have only local interaction. Two containment control algorithms via only position measurements of the agents are proposed. Theoretical analysis shows that the followers will move into the convex hull spanned by the dynamic leaders if the network topology among the followers is undirected, for each follower there exists at least one leader that has a directed path to the follower, and the parameters in the algorithm are properly chosen. Numerical results are provided to illustrate the theoretical results. © 2011 IEEE.


van Hees H.,Frankfurt Institute for Advanced Studies | van Hees H.,Institute for Theoretical Physics | He M.,Nanjing University of Science and Technology | Rapp R.,Texas A&M University
Nuclear Physics A | Year: 2015

We compute the spectra and elliptic flow of thermal photons emitted in ultrarelativistic heavy-ion collisions (URHICs) at RHIC and LHC. The thermal emission rates are taken from complete leading-order rates for the QGP and hadronic many-body calculations including baryons and antibaryons, as well as meson-exchange reactions (including Bremsstrahlung). We first update previous thermal fireball calculations by implementing a lattice-QCD based equation of state and extend them to compare to recent LHC data. We then scrutinize the space-time evolution of Au-Au collisions at RHIC by employing an ideal hydrodynamic model constrained by bulk- and multistrange-hadron spectra and elliptic flow, including a non-vanishing initial flow. We systematically compare the evolutions of temperature, radial flow, azimuthal anisotropy and four-volume, and exhibit the temperature profile of thermal photon radiation. Based on these insights, we put forward a scenario with a "pseudo-critical enhancement" of thermal emission rates, and investigate its impact on RHIC and LHC direct photon data. © 2014 Elsevier B.V.


Zuo C.,Nanjing University of Science and Technology | Zuo C.,Nanyang Technological University | Zuo C.,Beijing Institute of Technology | Chen Q.,Nanjing University of Science and Technology | And 3 more authors.
Optics Express | Year: 2013

Several existing strategies for estimating the axial intensity derivative in the transport-of-intensity equation (TIE) from multiple intensity measurements have been unified by the Savitzky-Golay differentiation filter - an equivalent convolution solution for differentiation estimation by least-squares polynomial fitting. The different viewpoint from the digital filter in signal processing not only provides great insight into the behaviors, the shortcomings, and the performance of these existing intensity derivative estimation algorithms, but more important, it also suggests a new way of improving solution strategies by extending the applications of Savitzky-Golay differentiation filter in TIE. Two novel methods for phase retrieval based on TIE are presented - the first by introducing adaptivedegree strategy in spatial domain and the second by selecting optimal spatial frequencies in Fourier domain. Numerical simulations and experiments verify that the second method outperforms the existing methods significantly, showing reliable retrieved phase with both overall contrast and fine phase variations well preserved. © 2013 Optical Society of America.


Wang L.,Nanjing University of Science and Technology | Wang L.,National University of Singapore | Guo Y.-X.,National University of Singapore | Sheng W.-X.,Nanjing University of Science and Technology
IEEE Transactions on Antennas and Propagation | Year: 2013

A 4× 4 L-probe patch antenna array using multilayer low temperature co-fired ceramic (LTCC) technology is presented for 60-GHz band applications. The proposed antenna array is designed with a high gain in the impedance bandwidth by introducing a novel soft-surface structure. The soft-surface structure comprised of metal strips and via fences reduces the losses caused by severe surface waves and mutual coupling between adjacent elements to improve the radiation performance. The proposed antenna array is convenient for integrated applications. The fabricated antenna array excluding the measurement transition has dimension of 14.4× 14.4× 1 mm3. The simulated and measured impedance and radiation performance are studied and compared. Good agreement is achieved between simulation and measurement. The proposed antenna array shows a wide simulated impedance of 29% from 53 GHz to 71 GHz for S11<-10 dB, measured broadband 3-dB gain bandwidth of 18.3% from 54.5 GHz to 65.5 GHz and the gain up to 17.5 dBi at 60 GHz, respectively. © 1963-2012 IEEE.


Cao X.,Nanjing University of Science and Technology | Jiang S.,Nanjing University of Science and Technology | Yu C.,Nanjing University of Science and Technology | Wang Y.,Nanjing University of Science and Technology | And 3 more authors.
Optics Express | Year: 2014

We present a theoretical investigation of high-order harmonic generation in spatially inhomogeneous two-color laser fields by solving three dimensional time dependent Schrödinger equation. The cutoff in the harmonic spectra can be significantly extended by means of our proposed method (i.e., from helium interacting with the plasmon-enhanced two-color laser fields), and an ultrabroad supercontinuum up to 1.5 keV is generated by selecting proper carrier-envelope phase of the controlling field. Moreover, classical trajectory extraction, time-dependent ionization and recombination rates, and time-frequency analyses are used to explain the generation of this ultrabroadband supercontinuum. As a result, an isolated 8.8 attosecond pulse can be generated directly by the superposition of the supercontinuum harmonics. © 2014 Optical Society of America.


Kan E.,Nanjing University of Science and Technology | Wu F.,Nanjing Forestry University | Xiang H.,Fudan University | Yang J.,Anhui University of Science and Technology | Whangbo M.-H.,North Carolina State University
Journal of Physical Chemistry C | Year: 2011

The BN zigzag nanoribbons (BNZNRs) were examined by first-principles density functional calculations, including structural relaxation. The quantum confinement and edge effects of the BNZNRs produce a magnetic ground state. When the B-edge is hydrogenated, the BNZNRs possess a new state with a spin-resloved Dirac point Fermi surface, which paves a way to realizing spin-polarized massless carriers. © 2011 American Chemical Society.


Xu W.,University of New South Wales | Birbilis N.,Monash University | Sha G.,Nanjing University of Science and Technology | Wang Y.,University of New South Wales | And 3 more authors.
Nature Materials | Year: 2015

Ultra-lightweight alloys with high strength, ductility and corrosion resistance are desirable for applications in the automotive, aerospace, defence, biomedical, sporting and electronic goods sectors. Ductility and corrosion resistance are generally inversely correlated with strength, making it difficult to optimize all three simultaneously. Here we design an ultralow density (1.4gcm-3) Mg-Li-based alloy that is strong, ductile, and more corrosion resistant than Mg-based alloys reported so far. The alloy is Li-rich and a solute nanostructure within a body-centred cubic matrix is achieved by a series of extrusion, heat-treatment and rolling processes. Corrosion resistance from the environment is believed to occur by a uniform lithium carbonate film in which surface coverage is much greater than in traditional hexagonal close-packed Mg-based alloys, explaining the superior corrosion resistance of the alloy. © 2015 Macmillan Publishers Limited. All rights reserved.


Ren R.,Nanjing University of Science and Technology | Ren R.,National University of Singapore | Guo Y.,National University of Singapore | Zhu R.,Nanjing University of Science and Technology
Optics Letters | Year: 2012

This Letter presents a crystalline silicon thin film solar cell model with Si nanowire arrays surface decoration and metallic nanostructure patterns on the back reflector. The nanostructured Ag back reflector can significantly enhance the absorption in the near-infrared spectrum. Furthermore, by inserting a ZnO:Al layer between the silicon substrate and nanostructured Ag back reflector, the absorption loss in the Ag back reflector can be clearly depressed, contributing to a maximum Jsc of 28.4 mA/cm2. A photocurrent enhancement of 22% is achieved compared with a SiNW solar cell with a planar Ag back reflector. © 2012 Optical Society of America.


Zhou Q.,Nanjing University of Science and Technology | Shi P.,University of Adelaide | Shi P.,Victoria University of Melbourne | Xu S.,Nanjing University of Science and Technology | Li H.,Bohai University
IEEE Transactions on Neural Networks and Learning Systems | Year: 2013

This paper considers the problem of observer-based adaptive neural network (NN) control for a class of single-input single-output strict-feedback nonlinear stochastic systems with unknown time delays. Dynamic surface control is used to avoid the so-called explosion of complexity in the backstepping design process. Radial basis function NNs are directly utilized to approximate the unknown and desired control input signals instead of the unknown nonlinear functions. The proposed adaptive NN output feedback controller can guarantee all the signals in the closed-loop system to be mean square semi-globally uniformly ultimately bounded. Simulation results are provided to demonstrate the effectiveness of the proposed methods. © 2012 IEEE.


Sheng C.,Nanjing University of Science and Technology | Sheng C.,University of Utah | Zhang C.,University of Utah | Zhai Y.,University of Utah | And 5 more authors.
Physical Review Letters | Year: 2015

We studied the ultrafast transient response of photoexcitations in two hybrid organic-inorganic perovskite films used for high efficiency photovoltaic cells, namely, CH3NH3PbI3 and CH3NH3PbI1.1Br1.9 using polarized broadband pump-probe spectroscopy in the spectral range of 0.3-2.7 eV with 300 fs time resolution. For CH3NH3PbI3 with above-gap excitation we found both photogenerated carriers and excitons, but only carriers are photogenerated with below-gap excitation. In contrast, mainly excitons are photogenerated in CH3NH3PbI1.1Br1.9. Surprisingly, we also discovered in CH3NH3PbI3, but not in CH3NH3PbI1.1Br1.9, transient photoinduced polarization memory for both excitons and photocarriers, which is also reflected in the steady state photoluminescence. From the polarization memory dynamics we obtained the excitons diffusion constant in CH3NH3PbI3, D≈0.01cm2s-1. © 2015 American Physical Society.


Rahman G.,Quaid-i-Azam University | Din N.U.,Quaid-i-Azam University | Garcia-Suarez V.M.,University of Oviedo | Garcia-Suarez V.M.,Nanomaterials and Nanotechnology Research Center | And 2 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

The magnetism and electronic structure of Li-doped SnO2 are investigated using first-principles LDA/LDA+U calculations. We find that Li induces magnetism in SnO2 when doped at the Sn site but becomes nonmagnetic when doped at the O and interstitial sites. The calculated formation energies show that Li prefers the Sn site as compared with the O site, in agreement with previous experimental works. The interaction of Li with native defects (Sn VSn and O VO vacancies) is also studied, and we find that Li not only behaves as a spin polarizer, but also a vacancy stabilizer, i.e., Li significantly reduces the defect formation energies of the native defects and helps the stabilization of magnetic oxygen vacancies. The electronic densities of states reveals that these systems, where the Fermi level touches the conduction (valence) band, are nonmagnetic (magnetic). © 2013 American Physical Society.


Xu L.-J.,Nanjing University of Science and Technology | Xu L.-J.,National University of Singapore | Guo Y.-X.,Nanjing University of Science and Technology | Wu W.,Nanjing University of Science and Technology
IEEE Antennas and Wireless Propagation Letters | Year: 2012

We present a dual-band implantable planar inverted-F antenna. Besides the resonance at 2.45-GHz Industrial, Scientific, and Medical (ISM) band, three closely spaced resonant frequencies are created at the lower band by adding open-end slots in the ground plane, resulting in a broad bandwidth covering Medical Implant Communication Services (MICS) band at 402 MHz and ISM band at 433 MHz. The measured frequencies range from 356 to 610 MHz (52.6%) at the lower band and from 2.42 to 2.53 GHz (4.4%) at the upper band for vert S11 less than-10 dB. The antenna occupies a compact size of 487.8 mm3 (19 mm×19.4 mm×1.27 mm). © 2002-2011 IEEE.


Zeng Z.,Nanjing University of Science and Technology | Ai Y.,Singapore University of Technology and Design | Qian S.,Old Dominion University
Physical Chemistry Chemical Physics | Year: 2014

Mimicking biological ion channels capable of pH-regulated ionic transport, synthetic nanopores functionalized with pH-tunable polyelectrolyte (PE) brushes have been considered as versatile tools for active transport control of ions, fluids, and bioparticles on the nanoscale. The ionic current rectification (ICR) phenomenon through a conical nanopore functionalized with PE brushes whose charge highly depends upon the local solution properties (i.e., pH and background salt concentration) is studied theoretically for the first time. The results show that the rectification magnitude, as well as the preferential rectification direction, is sensitive to the pH stimulus. The bulk concentration of the background salt can also significantly influence the charge of the PE brushes and accordingly affect the ICR phenomenon. The obtained results provide an insightful understanding of the pH-regulated ICR and guidelines for designing nanopores functionalized with PE brushes for pH-tunable applications. © 2014 the Owner Societies.


Chen W.,Nanjing University of Science and Technology | Wang L.,Nanjing University of Posts and Telecommunications
Neurocomputing | Year: 2013

In this paper, the problem of stochastic stability of neutral-type neural networks with Markovian jumping parameters is considered. By choosing an mode-dependent Lyapunov-Krasovskii functional, novel delay-dependent stochastically stable conditions are derived in terms of linear matrix inequalities. Numerical examples are given to illustrate the effectiveness of the proposed approach. © 2013 Elsevier B.V.


Lu C.,National University of Singapore | Tang J.,Nanjing University of Science and Technology | Yan S.,National University of Singapore | Lin Z.,Peking University
Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition | Year: 2014

As surrogate functions of 0-norm, many nonconvex penalty functions have been proposed to enhance the sparse vector recovery. It is easy to extend these nonconvex penalty functions on singular values of a matrix to enhance low-rank matrix recovery. However, different from convex optimization, solving the nonconvex low-rank minimization problem is much more challenging than the nonconvex sparse minimization problem. We observe that all the existing nonconvex penalty functions are concave and monotonically increasing on [0, ∞). Thus their gradients are decreasing functions. Based on this property, we propose an Iteratively Reweighted Nuclear Norm (IRNN) algorithm to solve the nonconvex nonsmooth low-rank minimization problem. IRNN iteratively solves a Weighted Singular Value Thresholding (WSVT) problem. By setting the weight vector as the gradient of the concave penalty function, the WSVT problem has a closed form solution. In theory, we prove that IRNN decreases the objective function value monotonically, and any limit point is a stationary point. Extensive experiments on both synthetic data and real images demonstrate that IRNN enhances the low-rank matrix recovery compared with state-of-the-art convex algorithms. © 2014 IEEE.


Chu H.,National University of Singapore | Chu H.,Nanjing University of Science and Technology | Guo Y.-X.,National University of Singapore | Wang Z.,Nanjing Electronic Devices Institute
IEEE Transactions on Antennas and Propagation | Year: 2013

Wideband 60-GHz vertical off-center dipole antenna and its arrays on low-temperature cofired ceramic substrate are presented in this paper. The dipole antenna is designed using the off-center-fed technology to cover all the four channels defined in 60-GHz standards from 57 to 66 GHz. A 4 \times 4 planar array is optimized to achieve a maximum gain of 15.6 dBi at 60 GHz and above 10.2 dBi in the passband, while a beam-steering array is optimized to give a 5-dB measured beamwidth wider than 80\circ at 60 GHz. Measured results indicate our designs meet the above requirements well and satisfy 60-GHz applications. © 1963-2012 IEEE.


Chen W.,Nanjing University of Science and Technology | Wang L.,Nanjing University of Posts and Telecommunications
Journal of the Franklin Institute | Year: 2014

In this paper, the problem of H∞ filtering of uncertain time-delay systems with Markovian jumping parameters is considered. Firstly, by utilizing the delay-partitioning idea, an augmented mode-dependent Lyapunov functional is employed to analyze the stochastic stability and H∞ performance of the resulting filtering error systems. It is noted that the derived performance analysis results are less conservative than the recent ones in the literature. Secondly, based on the criteria obtained, a desired filter can be constructed by introducing a given nonsingular matrix and a scalar. Numerical examples are given to illustrate the effectiveness of the proposed approach. © 2013 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.


Yeh L.-H.,National Yunlin University of Science and Technology | Hughes C.,Old Dominion University | Zeng Z.,Nanjing University of Science and Technology | Qian S.,Old Dominion University
Analytical Chemistry | Year: 2014

Inspired by ion channels in biological cells where the intracellular and extracellular ionic concentrations are typically different, a salt concentration gradient through a charged nanopore is proposed to actively regulate its ion transport and selectivity. Results obtained show that, in addition to the ion current rectification phenomenon, a reversed ion selectivity of the nanopore occurs when the concentration gradient is sufficiently large. In addition, if the directions of the applied concentration gradient and electric field are identical, a reversed magnified electric field occurs near the cathode side of the nanopore. This induced field can be used to enhance the capture rate of biomolecules and is therefore capable of improving the performance of single biomolecule sensing using nanopores. © 2014 American Chemical Society.


Ai Y.,Singapore University of Technology and Design | Zeng Z.,Nanjing University of Science and Technology | Qian S.,Old Dominion University
Journal of Colloid and Interface Science | Year: 2014

Under an AC electric field, individual particles in close proximity induce spatially non-uniform electric field around each other, accordingly resulting in mutual dielectrophoretic (DEP) forces on these particles. The resulting attractive DEP particle-particle interaction could assemble individual colloidal particles or biological cells into regular patterns, which has become a promising bottom-up fabrication technique for bio-composite materials and microscopic functional structures. In this study, we developed a transient multiphysics model under the thin electric double layer (EDL) assumption, in which the fluid flow field, AC electric field and motion of finite-size particles are simultaneously solved using an Arbitrary Lagrangian-Eulerian (ALE) numerical approach. Numerical simulations show that negative DEP particle-particle interaction always tends to attract particles and form a chain parallel to the applied electric field. Particles usually accelerate at the first stage of the attractive motion due to an increase in the DEP interactive force, however, decelerate until stationary at the second stage due to a faster increase in the repulsive hydrodynamic force. Identical particles move at the same speed during the interactive motion. In contrast, smaller particles move faster than bigger particles during the attractive motion. The developed model explains the basic mechanism of AC DEP-based particle assembly technique and provides a versatile tool to design microfluidic devices for AC DEP-based particle or cell manipulation. © 2013 Elsevier Inc.


Xia H.,Nanjing University of Science and Technology | Luo Z.,National University of Singapore | Xie J.,National University of Singapore
Nanotechnology Reviews | Year: 2014

Lithium-ion (Li-ion) batteries with high energy and power are promising power sources for electric vehicles (including hybrid electric vehicles). One of the challenges is to develop advanced anode materials with high safety, good cycling stability, and fast charge/discharge capabilities. The Li4Ti5O12 spinel is a state-of-the-art Li-ion battery anode material owing to its outstanding safety and excellent structural stability during cycling. However, Li4Ti5O12 large particles still suffer from low ionic conductivity and electronic conductivity, which result in poor rate performance and inhibit its wide practical application. Developing nanostructured electrode materials is one of the most attractive strategies to dramatically enhance the electrochemical performance, including capacity, rate capability, and cycling life. Currently, extensive efforts have been devoted to developing nanostructured Li4Ti5O12 and Li4Ti5O12/carbon nanocomposites to improve their rate performance for high-power Li-ion batteries. In this article, we review the recent progress in developing nanostructured Li4Ti5O12 and Li4Ti5O12/carbon nanocomposites and discuss the benefits of nanostructure and carbon incorporation for the electrochemical performance of Li4Ti5O12-based anodes.


Chen G.,Nanjing University of Science and Technology | Chen G.,Jiangsu Institute of Advanced Materials | Cheng J.L.,Nanjing University of Science and Technology | Cheng J.L.,Jiangsu Institute of Advanced Materials | Liu C.T.,City University of Hong Kong
Intermetallics | Year: 2012

A large-sized Zr-based BMG composite containing coarse and spherical β-Zr precipitates was produced using the semi-solid progressive solidification (SSPS) method. Specimens with a 6-mm-diameter gauge section fabricated from 11-mm-diameter cast rods, which are at least twice larger than those reported previously, have been used for mechanical-property evaluation. Our results show that the composite exhibits both excellent work hardening and plasticity. Both the microstructure evolution as a function of isothermal temperature & holding time and its influence on the mechanical properties were investigated. The mechanical properties of the composite are found to be closely related to microstructural features, and the tensile plasticity can be enhanced significantly with increasing the size scale of β-Zr precipitates. It's evidenced that β-Zr precipitates yield firstly and the plastic deformation with a significant work hardening follows as the stress exceeds the maximum elastic stress. Shear bands are found to be essentially nucleated at the interface between the β-Zr particle and the glassy matrix. With further loading, the strain softening induced by the plastic deformation of the glass matrix increases. When the capacity of the strain softening by the matrix offsets the contribution of the work-hardening by the β-Zr precipitates, the stress will reach the maximum value and then the necking occurs. The mechanistic understanding of the deformation mechanism in the large-sized BMG composite sheds light on the design of BMG composites with enhanced mechanical properties. © 2012 Elsevier Ltd. All rights reserved.


Zhu D.,Nanjing University of Science and Technology | Yuan G.,Nanjing University of Science and Technology | Xia H.,Nanjing University of Science and Technology
Chemical Communications | Year: 2014

Ti nanowire arrays (NAs) prepared by a facile and template-free hydrothermal method were used as three-dimensional (3D) current collectors for the electrodeposition of MnO2. The resulting Ti@MnO2 NAs exhibit remarkable electrochemical behavior with high specific capacitance, good rate performance and desired cycling stability. © 2014 The Royal Society of Chemistry.


Chu H.,Nanjing University of Science and Technology | Shi X.Q.,Nanjing University of Science and Technology | Guo Y.X.,National University of Singapore
Journal of Electromagnetic Waves and Applications | Year: 2011

A novel ultra-wideband (UWB) bandpass filter (BPF) with a notch band is proposed and implemented. The filter is realized by using a high pass filter (HPF) and an array of multiband electromagnetic bandgap (EBG) cells etched on the ground of a 50 Ω microstrip line. The first and third stopband of the designed EBG array generate the edges at each side of the passband of the UWB BPF, while the second stopband creates a very sharp notch response. Since it is the passband of the designed EBG array at lower frequency, a HPF is involved. To the authors' knowledge, we present for the first time a sharp notch band generated by using an EBG array in UWB BPF. The proposed filter was successfully designed, simulated and fabricated. The measured results show that the proposed BPF has a wide bandwidth from 3.8 GHz to 10.1 GHz with a notch response centered at 5.1 GHz. Both simulated and measured results are described. © 2011 VSP.


Shen F.,University of Adelaide | Shen F.,Nanjing University of Science and Technology | Shen C.,University of Adelaide | Shi Q.,University of Adelaide | And 2 more authors.
Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition | Year: 2013

Learning based hashing methods have attracted considerable attention due to their ability to greatly increase the scale at which existing algorithms may operate. Most of these methods are designed to generate binary codes that preserve the Euclidean distance in the original space. Manifold learning techniques, in contrast, are better able to model the intrinsic structure embedded in the original high-dimensional data. The complexity of these models, and the problems with out-of-sample data, have previously rendered them unsuitable for application to large-scale embedding, however. In this work, we consider how to learn compact binary embeddings on their intrinsic manifolds. In order to address the above-mentioned difficulties, we describe an efficient, inductive solution to the out-of-sample data problem, and a process by which non-parametric manifold learning may be used as the basis of a hashing method. Our proposed approach thus allows the development of a range of new hashing techniques exploiting the flexibility of the wide variety of manifold learning approaches available. We particularly show that hashing on the basis of t-SNE [29] outperforms state-of-the-art hashing methods on large-scale benchmark datasets, and is very effective for image classification with very short code lengths. © 2013 IEEE.


Xia H.,Nanjing University of Science and Technology | Xiong W.,Nanjing University of Science and Technology | Yao Q.,National University of Singapore | Xie J.,National University of Singapore
Nano Research | Year: 2014

This paper reports a simple yet efficient method for the synthesis of hierarchical TiO2-B nanowire@α-Fe2O3 nanothorn core-branch arrays based on a stepwise hydrothermal approach. The as-fabricated hybrid arrays show impressive performance as a high-capacity anode for lithium-ion batteries. The key design in this study is a core-branch hybrid architecture, which not only provides large surface active sites for lithium ion insertion/extraction, but also enables fast charge transport owing to the reduced diffusion paths for both electrons and lithium ions. The peculiar combination of attributes of TiO2 (good structural stability) and Fe2O3 (large specific capacity) provides the hybrid array electrodes with several desirable electrochemical features: large reversible capacity (∼800 mA·h·g−1 for specific mass capacity and ∼750 μA·h·cm−2 for specific areal capacity), good cycling stability, and high rate capability. The impressive electrochemical performance, together with the facile synthesis procedure, may provide an efficient platform to integrate the TiO2 nanowire@Fe2O3 nanothorn core-branch arrays as a three-dimensional thin film electrode for lithium-ion microbatteries.[Figure not available: see fulltext.]. © 2014, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.


Xia J.,University of Oklahoma | Chen J.,Nanjing University of Science and Technology | Chen J.,University of Toledo | Piao S.,Peking University | And 4 more authors.
Nature Geoscience | Year: 2014

Feedbacks between the terrestrial carbon cycle and climate change could affect many ecosystem functions and services, such as food production, carbon sequestration and climate regulation. The rate of climate warming varies on diurnal and seasonal timescales. A synthesis of global air temperature data reveals a greater rate of warming in winter than in summer in northern mid and high latitudes, and the inverse pattern in some tropical regions. The data also reveal a decline in the diurnal temperature range over 51% of the global land area and an increase over only 13%, because night-time temperatures in most locations have risen faster than daytime temperatures. Analyses of satellite data, model simulations and in situ observations suggest that the impact of seasonal warming varies between regions. For example, spring warming has largely stimulated ecosystem productivity at latitudes between 30and 90N, but suppressed productivity in other regions. Contrasting impacts of day- and night-time warming on plant carbon gain and loss are apparent in many regions. We argue that ascertaining the effects of non-uniform climate warming on terrestrial ecosystems is a key challenge in carbon cycle research. © 2014 Macmillan Publishers Limited.


Zhang C.,University of Utah | Sun D.,University of Utah | Sheng C.-X.,University of Utah | Sheng C.-X.,Nanjing University of Science and Technology | And 4 more authors.
Nature Physics | Year: 2015

Magnetic field effects have been a successful tool for studying carrier dynamics in organic semiconductors as the weak spin-orbit coupling in these materials gives rise to long spin relaxation times. As the spin-orbit coupling is strong in organic-inorganic hybrid perovskites, which are promising materials for photovoltaic and light-emitting applications, magnetic field effects are expected to be negligible in these optoelectronic devices. We measured significant magneto-photocurrent, magneto-electroluminescence and magneto-photoluminescence responses in hybrid perovskite devices and thin films, where the amplitude and shape are correlated to each other through the electron-hole lifetime, which depends on the perovskite film morphology. We attribute these responses to magnetic-field-induced spin-mixing of the photogenerated electron-hole pairs with different g-factors - the Δg model. We validate this model by measuring large Δg (∼ 0.65) using field-induced circularly polarized photoluminescence, and electron-hole pair lifetime using picosecond pump-probe spectroscopy.


Xia R.,Nanjing University of Science and Technology | Zong C.,Chinese Academy of Sciences | Hu X.,Nanjing University of Science and Technology | Cambria E.,National University of Singapore
IEEE Intelligent Systems | Year: 2013

Domain adaptation problems often arise often in the field of sentiment classification. Here, the feature ensemble plus sample selection (SS-FE) approach is proposed, which takes labeling and instance adaptation into account. A feature ensemble (FE) model is first proposed to learn a new labeling function in a feature reweighting manner. Furthermore, a PCA-based sample selection (PCA-SS) method is proposed as an aid to FE. Experimental results show that the proposed SS-FE approach could gain significant improvements, compared to FE or PCA-SS, because of its comprehensive consideration of both labeling adaptation and instance adaptation. © 2013 IEEE.


Xia H.,Nanjing University of Science and Technology | Wang Y.,Institute of Chemical and Engineering Sciences, Singapore | Lin J.,Institute of Chemical and Engineering Sciences, Singapore | Lu L.,National University of Singapore
Nanoscale Research Letters | Year: 2012

MnO 2/carbon nanotube [CNT] nanocomposites with a CNT core/porous MnO 2 sheath hierarchy architecture are synthesized by a simple hydrothermal treatment. X-ray diffraction and Raman spectroscopy analyses reveal that birnessite-type MnO 2 is produced through the hydrothermal synthesis. Morphological characterization reveals that three-dimensional hierarchy architecture is built with a highly porous layer consisting of interconnected MnO 2 nanoflakes uniformly coated on the CNT surface. The nanocomposite with a composition of 72 wt.% (K 0.2MnO 2·0.33H 2O)/28 wt.% CNT has a large specific surface area of 237.8 m 2/g. Electrochemical properties of the CNT, the pure MnO 2, and the MnO 2/CNT nanocomposite electrodes are investigated by cyclic voltammetry and electrochemical impedance spectroscopy measurements. The MnO 2/CNT nanocomposite electrode exhibits much larger specific capacitance compared with both the CNT electrode and the pure MnO 2 electrode and significantly improves rate capability compared to the pure MnO 2 electrode. The superior supercapacitive performance of the MnO 2/CNT nancomposite electrode is due to its high specific surface area and unique hierarchy architecture which facilitate fast electron and ion transport. © 2012 Xia et al.


Ge L.,Nanjing University of Science and Technology | Wang J.P.,Nanjing University of Science and Technology | Guo Y.-X.,National University of Singapore
Electronics Letters | Year: 2010

A compact microstrip lowpass filter with an ultra-wide stopband is proposed. To achieve wide stopband suppression and compact size, both symmetrically loaded resonant patches and meander transmission line are adopted. A demonstration filter with 3dB cutoff frequency at 1.3GHz has been designed, fabricated and measured. The proposed filter also exhibits a very wide stopband of 152, and is able to suppress the eleventh-harmonic response together with a small size of 0.12λg × 0.071λg, where λg is the guided wavelength at 1.3GHz. © 2010 The Institution of Engineering and Technology.


Yang J.,Nanjing University of Science and Technology | Chu D.,National University of Singapore | Zhang L.,Hong Kong Polytechnic University | Xu Y.,Harbin Institute of Technology
IEEE Transactions on Neural Networks and Learning Systems | Year: 2013

A sparse representation-based classifier (SRC) is developed and shows great potential for real-world face recognition. This paper presents a dimensionality reduction method that fits SRC well. SRC adopts a class reconstruction residual-based decision rule, we use it as a criterion to steer the design of a feature extraction method. The method is thus called the SRC steered discriminative projection (SRC-DP). SRC-DP maximizes the ratio of between-class reconstruction residual to within-class reconstruction residual in the projected space and thus enables SRC to achieve better performance. SRC-DP provides low-dimensional representation of human faces to make the SRC-based face recognition system more efficient. Experiments are done on the AR, the extended Yale B, and PIE face image databases, and results demonstrate the proposed method is more effective than other feature extraction methods based on the SRC. © 2012 IEEE.


Xia H.,Nanjing University of Science and Technology | Li B.,Nanjing University of Science and Technology | Lu L.,National University of Singapore
RSC Advances | Year: 2014

Nanocrystalline Ru film is deposited on Ni foam by a chemical replacement reaction. The deposited Ru film exhibits a mesoporous structure comprising nanocrystallites and nanopores of 2-3 nm in diameter. A 1.8 V symmetric supercapacitor is developed using nanocrystalline Ru films as both negative and positive electrodes. © 2014 The Royal Society of Chemistry.


Jin Z.,Nanjing University of Posts and Telecommunications | Jin Z.,Nanjing University of Science and Technology | Yang X.,Nanjing University of Science and Technology
Journal of Mathematical Imaging and Vision | Year: 2011

In this paper we study a variational model to deal with the speckle noise in ultrasound images. We prove the existence and uniqueness of the minimizer for the variational problem, and derive the existence and uniqueness of weak solutions for the associated evolution equation. Furthermore, we show that the solution of the evolution equation converges weakly in BV and strongly in L 2 to the minimizer as t→∞. Finally, some numerical results illustrate the effectiveness of the proposed model for multiplicative noise removal. © 2010 Springer Science+Business Media, LLC.


Xia H.,Nanjing University of Science and Technology | Ragavendran K.R.,Bar - Ilan University | Xie J.,National University of Singapore | Lu L.,National University of Singapore
Journal of Power Sources | Year: 2012

Ultrafine LiMn 2O 4/carbon nanotube (CNT) nanocomposite is synthesized by a one-step hydrothermal treatment. In the nanocomposite, LiMn 2O 4 nanoparticles of 10-20 nm in diameters are well crystallized and uniformly distributed in the CNT matrix. The CNTs not only provide a conductive matrix, facilitating fast electron transport, but also effectively reduce agglomeration of LiMn 2O 4 nanoparticles. The nano-LiMn 2O 4/CNT nanocomposite exhibits superior rate capability and cycling stability compared with the sol-gel synthesized LiMn 2O 4, making it promising for high-power applications. © 2012 Elsevier B.V. All rights reserved.


Tang G.,Nanjing University of Science and Technology | Shi X.,Nanjing University of Science and Technology | Huo C.,China Institute of Metrology | Wang Z.,Nanjing University
Ceramics International | Year: 2013

The fabrication and magnetic characteristics of Ni and Cu co-doped ZnO nanorods are reported. The Ni and Cu co-doped ZnO nanorods are synthesized by a facile hydrothermal method. Structural characterizations reveal that Ni and Cu ions enter into ZnO lattices without any secondary phases. SEM images show that they are regular nanorods. Magnetic measurements indicate that the obtained rod arrays exhibit room-temperature ferromagnetic behaviors. The exchange interaction between free delocalized carriers (holes from valence band) and the localized d spins of Ni and Cu ions is considered as the cause of the room-temperature ferromagnetism. © 2012 Elsevier Ltd and Techna Group S.r.l.


Ye J.,Nanjing University of Science and Technology | Ye J.,Nanjing University of Posts and Telecommunications | Jin Z.,Nanjing University of Science and Technology
Neurocomputing | Year: 2014

In past decades, tremendous growths in the amount of text documents and images have become omnipresent, and it is very important to group them into clusters upon desired. Recently, matrix factorization based techniques, such as Non-negative Matrix Factorization (NMF) and Concept Factorization (CF), have yielded impressive results for clustering. However, both of them effectively see only the global Euclidean geometry, whereas the local manifold geometry is not fully considered. Recent research has shown that not only the observed data are found to lie on a nonlinear low dimensional manifold, namely data manifold, but also the features lie on a manifold, namely feature manifold. In this paper, we propose a novel algorithm, called dual-graph regularized concept factorization for clustering (GCF), which simultaneously considers the geometric structures of both the data manifold and the feature manifold. As an extension of GCF, we extend that our proposed method can also be apply to the negative dataset. Moreover, we develop the iterative updating optimization schemes for GCF, and provide the convergence proof of our optimization scheme. Experimental results on TDT2 and Reuters document datasets, COIL20 and PIE image datasets demonstrate the effectiveness of our proposed method. © 2014 Elsevier B.V.


Wu F.,Nanjing Forestry University | Liu Y.,Nanjing Forestry University | Yu G.,Nanjing Forestry University | Shen D.,Nanjing Forestry University | And 2 more authors.
Journal of Physical Chemistry Letters | Year: 2012

Although graphitic C3N4 (g-C3N 4) has been demonstrated to be a potential candidate for solar cell absorber and photovoltaic materials, the application has been limited by the low photoconversion efficiency in the visible range. Here, we explored that a g-C3N4 bilayer has much better visible-light adsorption than a single layer via first-principles calculations, and the calculated optical adsorption threshold of bilayer significantly shifts downward by 0.8 eV, which is induced by the interlayer coupling. Additionally, we also found that the optical energy gap of bilayer can be engineered by the external electric field. The insights obtained in this study are general and will be helpful for future studies of two-dimensional solar cell absorber and photovoltaic materials. © 2012 American Chemical Society.


Zhou Q.,Nanjing University of Science and Technology | Zhou Q.,University of Portsmouth | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | And 3 more authors.
IEEE Transactions on Fuzzy Systems | Year: 2013

In this paper, the problem of adaptive fuzzy tracking control via output feedback for a class of uncertain single-input single-output (SISO) strict-feedback nonlinear systems with unknown time-delay functions is investigated. Dynamic surface control technique is used to avoid the problem of 'explosion of complexity,' which is caused by repeated differentiation of certain nonlinear functions in the backstepping design process. In addition, the fuzzy logic systems are utilized to approximate the unknown and desired control input signals directly instead of the unknown nonlinear functions. The designed controller can guarantee all the signals in the closed-loop system to be semiglobally uniformly ultimately bounded and the tracking error to converge to a small neighborhood of the origin. Simulations results are provided to demonstrate the effectiveness of the proposed methods. © 1993-2012 IEEE.


Gao Y.,Tsinghua National Laboratory for Information Sciences and Technology | Tang J.,Nanjing University of Science and Technology | Hong R.,Hefei University of Technology | Yan S.,National University of Singapore | And 3 more authors.
IEEE Transactions on Image Processing | Year: 2012

Recently, extensive research efforts have been dedicated to view-based methods for 3-D object retrieval due to the highly discriminative property of multiviews for 3-D object representation. However, most of state-of-the-art approaches highly depend on their own camera array settings for capturing views of 3-D objects. In order to move toward a general framework for 3-D object retrieval without the limitation of camera array restriction, a camera constraint-free view-based (CCFV) 3-D object retrieval algorithm is proposed in this paper. In this framework, each object is represented by a free set of views, which means that these views can be captured from any direction without camera constraint. For each query object, we first cluster all query views to generate the view clusters, which are then used to build the query models. For a more accurate 3-D object comparison, a positive matching model and a negative matching model are individually trained using positive and negative matched samples, respectively. The CCFV model is generated on the basis of the query Gaussian models by combining the positive matching model and the negative matching model. The CCFV removes the constraint of static camera array settings for view capturing and can be applied to any view-based 3-D object database. We conduct experiments on the National Taiwan University 3-D model database and the ETH 3-D object database. Experimental results show that the proposed scheme can achieve better performance than state-of-the-art methods. © 2011 IEEE.


Shen C.,University of Adelaide | Wang P.,Beihang University | Shen F.,Nanjing University of Science and Technology | Wang H.,Xiamen University | Wang H.,University of Adelaide
IEEE Transactions on Pattern Analysis and Machine Intelligence | Year: 2012

It has been shown that the Universum data, which do not belong to either class of the classification problem of interest, may contain useful prior domain knowledge for training a classifier [1], [2]. In this work, we design a novel boosting algorithm that takes advantage of the available Universum data, hence the name UBoost. UBoost is a boosting implementation of Vapnik's alternative capacity concept to the large margin approach. In addition to the standard regularization term, UBoost also controls the learned model's capacity by maximizing the number of observed contradictions. Our experiments demonstrate that UBoost can deliver improved classification accuracy over standard boosting algorithms that use labeled data alone. © 2012 IEEE.


Li Z.C.,Nanjing University of Science and Technology | Li Z.C.,Nanjing Forestry University | Wang J.,Nanjing University of Science and Technology
Smart Materials and Structures | Year: 2012

This research aims to design and control a full scale gun recoil buffering system which works under real firing impact loading conditions. A conventional gun recoil absorber is replaced with a controllable magnetorheological (MR) fluid damper. Through dynamic analysis of the gun recoil system, a theoretical model for optimal design and control of the MR fluid damper for impact loadings is derived. The optimal displacement, velocity and optimal design rules are obtained. By applying the optimal design theory to protect against impact loadings, an MR fluid damper for a full scale gun recoil system is designed and manufactured. An experimental study is carried out on a firing test rig which consists of a 30mm caliber, multi-action automatic gun with an MR damper mounted to the fixed base through a sliding guide. Experimental buffering results under passive control and optimal control are obtained. By comparison, optimal control is better than passive control, because it produces smaller variation in the recoil force while achieving less displacement of the recoil body. The optimal control strategy presented in this paper is open-loop with no feedback system needed. This means that the control process is sensor-free. This is a great benefit for a buffering system under impact loading, especially for a gun recoil system which usually works in a harsh environment. © 2012 IOP Publishing Ltd.


Tang J.,Nanjing University of Science and Technology | Zha Z.-J.,National University of Singapore | Tao D.,Intelligent Systems Technology, Inc. | Chua T.-S.,National University of Singapore
IEEE Transactions on Image Processing | Year: 2012

User interaction is an effective way to handle the semantic gap problem in image annotation. To minimize user effort in the interactions, many active learning methods were proposed. These methods treat the semantic concepts individually or correlatively. However, they still neglect the key motivation of user feedback: to tackle the semantic gap. The size of the semantic gap of each concept is an important factor that affects the performance of user feedback. User should pay more efforts to the concepts with large semantic gaps, and vice versa. In this paper, we propose a semantic-gap-oriented active learning method, which incorporates the semantic gap measure into the information-minimization- based sample selection strategy. The basic learning model used in the active learning framework is an extended multilabel version of the sparse-graph-based semisupervised learning method that incorporates the semantic correlation. Extensive experiments conducted on two benchmark image data sets demonstrated the importance of bringing the semantic gap measure into the active learning process. © 2011 IEEE.


Xia H.,Nanjing University of Science and Technology | Shirley Meng Y.,University of California at San Diego | Yuan G.,Nanjing University of Science and Technology | Cui C.,Nanjing University of Science and Technology | Lu L.,National University of Singapore
Electrochemical and Solid-State Letters | Year: 2012

A novel symmetric RuO 2RuO 2 supercapacitor with a high operating voltage of 1.6 V is built using the nanocrystalline hydrous RuO 2. The symmetric supercapacitor exhibits an energy density of 18.77 Wh kg -1 at a power density of 500 W kg -1 based on the total mass of active electrode material and excellent cycling stability and power capability. These results demonstrate the potentialities of using RuO 2 for symmetric supercapacitor or using RuO 2 as negative electrode for asymmetric supercapacitor with high energy density. © 2012 The Electrochemical Society.


Camarillo-Cisneros J.,Fritz Haber Institute | Camarillo-Cisneros J.,CIMAV | Liu W.,Fritz Haber Institute | Liu W.,Nanjing University of Science and Technology | Tkatchenko A.,Fritz Haber Institute
Physical Review Letters | Year: 2015

The study of how molecules adsorb, diffuse, interact, and desorb from imperfect surfaces is essential for a complete understanding of elementary surface processes under relevant pressure and temperature conditions. Here we use first-principles calculations to study the adsorption of benzene and naphthalene on a vicinal Cu(443) surface with the aim to gain insight into the behavior of aromatic hydrocarbons on realistic surfaces at a finite temperature. Upon strong adsorption at step edges at a low temperature, the molecules then migrate from the step to the (111) terraces, where they can freely diffuse parallel to the step edge. This migration happens at temperatures well below the onset of desorption, suggesting a more complex dynamical picture than previously proposed from temperature-programed desorption studies. The increase of the adsorption strength observed in experiments for Cu(443) when compared to Cu(111) is explained by a stronger long-range van der Waals attraction between the hydrocarbons and the step edges of the Cu(443) surface. Our calculations highlight the need for time-resolved experimental studies to fully understand the dynamics of molecular layers on surfaces. © 2015 American Physical Society.


Zhao H.,Huaiyin Institute of Technology | Ren W.,University of California at Riverside | Yuan D.,Nanjing University of Science and Technology | Chen J.,Beijing Institute of Technology
Systems and Control Letters | Year: 2012

This paper deals with the distributed discrete-time coordinated tracking problem for multi-agent systems with Markovian switching topologies. In the multi-agent team, only some of the agents can obtain the leader's state directly. The leader's state considered is time varying. We present necessary and sufficient conditions for boundedness of the tracking error system and show the ultimate bound of the tracking errors. A linear matrix inequality approach is developed to determine the allowable sampling period and the feasible control gain. A simulation example is given to illustrate the effectiveness of the results. © 2012 Elsevier Ltd. All rights reserved.


Shen H.,Nanjing University of Science and Technology | Xu S.,Nanjing University of Science and Technology | Zhou J.,Nanjing University of Science and Technology | Lu J.,Nantong University
International Journal of Systems Science | Year: 2011

This article is concerned with the problem of H∞ filter design for nonlinear Markovian jump neutral systems through the Takagi-Sugeno fuzzy model approach. By using a novel Markovian switched Lyapunov functional, a delay-dependent bounded real lemma (BRL) is presented in terms of linear matrix inequalities. Based on the derived BRL, both normal H∞ filters and non-fragile H∞ filters are designed, which guarantee that the corresponding filtering error systems are stochastically stable with a specified H∞ performance level. A numerical example is given to demonstrate the effectiveness of the proposed approach. © 2011 Taylor & Francis.


Xu L.,Nanjing University of Information Science and Technology | Li X.,Nanjing University of Science and Technology | Chen Y.,Nanjing University of Information Science and Technology | Xu F.,Nanjing University of Information Science and Technology
Applied Surface Science | Year: 2011

In this work, ZnO thin films with different thickness were prepared by sol-gel method on glass substrates and the structural and optical properties of these films were studied by X-ray diffractometer, atomic force microscope, UV-visible spectrophotometer, ellipsometer and fluorophotometer, respectively. The structural analyses show that all the samples have a wurtzite structure and are preferentially oriented along the c-axis perpendicular to the substrate surface. The growth process of highly c-axis oriented ZnO thin films derived from sol-gel method is a self-template process. With the increase of film thickness, the structural disorder decreases and the crystalline quality of the films is gradually improved. A transition of crystal growth mode from vertical growth to lateral growth is observed and the transition point is found between 270 and 360 nm thickness. The optical analyses show that with the increase of film thickness, both the refractive index and ultraviolet emission intensity are improved. However, the transmittance in the visible range is hardly influenced by the film thickness, and the averages are all above 80%. © 2010 Elsevier B.V.


Huang X.,Nanjing University of Information Science and Technology | Zhang J.,Nanjing Center | Xiao S.,Nanjing University of Information Science and Technology | Sang T.,Nanjing University of Science and Technology | Chen G.,Nanjing University of Information Science and Technology
Materials Letters | Year: 2014

The ZnFe2O4 ferrite nanoparticle and nanofiber were synthesized by electrospinning method. The phase composition, morphology, magnetic and electromagnetic properties were analyzed. The results showed that both the samples exhibited a pure phase of spinel type ferrite. The ZnFe 2O4 ferrite nanoparticle was aggregated, while the ZnFe2O4 ferrite nanofiber performed the homogeneous nano-fibrous shape as well as single-particle-chain structure. The magnetic analysis indicated that the ZnFe2O4 ferrite nanofiber showed ferromagnetic behaviour. Moreover, the dielectric loss and magnetic loss properties of ZnFe2O4 ferrite nanofiber were both enhanced due to its better dipole polarization, interfacial polarization and shape anisotropy. © 2014 Elsevier B.V.


Chen Y.-Y.,Nanjing University of Information Science and Technology | Wang J.,Nanjing University of Science and Technology | Wang Q.-H.,Nanjing University of Science and Technology | Li Z.-H.,Nanjing University of Science and Technology
Optics Letters | Year: 2012

In this Letter, moiré and emission tomography are integrated to visualize and diagnose high-temperature flow fields, and a jet flame is chosen as a practical example for experiment. The refractive index and intensity distributions are simultaneously obtained by moiré and emission tomography, respectively. Based on the intensity distribution, the structure of the jet flame is well visualized, so that the spatial distribution of species composition can be considered in the temperature reconstruction process. Finally, the refractive index and intensity distributions are matched, and a partition model is adopted to reconstruct the temperature distribution of the jet flame. © 2012 Optical Society of America.


Kowalczyk P.J.,MacDiarmid Institute for Advanced Materials and Nanotechnology | Kowalczyk P.J.,University of Lodz | Mahapatra O.,MacDiarmid Institute for Advanced Materials and Nanotechnology | Brown S.A.,MacDiarmid Institute for Advanced Materials and Nanotechnology | And 4 more authors.
Nano Letters | Year: 2013

We show that bismuth nanostructures form three-dimensional patterns governed by two-dimensional electronic effects. Scanning tunneling microscopy reveals that both the vertical and the lateral dimensions of the structures strongly favor certain values and that the preferred widths are substantially different for each preferred height. First-principles calculations demonstrate that this vertical-lateral correlation is governed by the Fermi surface topology and that this is itself sensitively dependent on the dimensions of the structure. © 2012 American Chemical Society.


Zuo C.,Nanjing University of Science and Technology | Zuo C.,Nanyang Technological University | Chen Q.,Nanjing University of Science and Technology | Huang L.,Brookhaven National Laboratory | Asundi A.,Nanyang Technological University
Optics Express | Year: 2014

The transport of intensity equation (TIE) has long been recognized as a quantitative method for phase retrieval and phase contrast imaging. However, it is shown that the most widely accepted fast Fourier transform (FFT) based solutions do not provide an exact solution to the TIE in general. The root of the problem lies in the so-called "Teague's assumption" that the transverse flux is considered to be a conservative field, which cannot be satisfied for a general object. In this work, we present the theoretical analysis of the phase discrepancy owing to the Teague's assumption, and derive the necessary and sufficient conditions for the FFT-based solution to coincide with the exact phase. An iterative algorithm is then proposed aiming to compensate such phase discrepancy in a simple yet effective manner. © 2014 Optical Society of America.


Cong S.,Heilongjiang University | Zou Y.,Nanjing University of Science and Technology
International Journal of Systems Science | Year: 2010

On the basis of the Lyapunov-Krasovskii method, the exponential stability in the mean square sense is investigated for Ito stochastic systems with Markovian switching and time-varying delay. The statistic properties of the Markov process and Brownian motion are employed to compute the constructed Lyapunov-Krasovskii functional of a rather general form. This enables us to make sense of the challenging problems in the stochastic framework, and then find a way to extend the techniques developed in the deterministic framework. Therefore, the stability conditions are established with the aid of some slack matrices and the boundary conditions on time-varying delay. Numerical examples are given to demonstrate the reduced conservatism. © 2010 Taylor & Francis.


Chen M.Z.Q.,University of Hong Kong | Hu Y.,Nanjing University of Science and Technology | Huang L.,University of Hong Kong | Huang L.,Zhejiang Institute of Research and Innovation | Chen G.,City University of Hong Kong
Journal of Sound and Vibration | Year: 2014

This paper investigates the influence of inerter on the natural frequencies of vibration systems. First of all, the natural frequencies of a single-degree-of-freedom (SDOF) system and a two-degree-of-freedom (TDOF) system are derived algebraically and the fact that the inerter can reduce the natural frequencies of these systems is demonstrated. Then, to further investigate the influence of inerter in a general vibration system, a multi-degree-of-freedom system (MDOF) is considered. Sensitivity analysis is performed on the natural frequencies and mode shapes to demonstrate that the natural frequencies of the MDOF system can always be reduced by increasing the inertance of any inerter. The condition for a general MDOF system of which the natural frequencies can be reduced by an inerter is also derived. Finally, the influence of the inerter position on the natural frequencies is investigated and the efficiency of inerter in reducing the largest natural frequencies is verified by simulating a six-degree-of-freedom system, where a reduction of more than 47 percent is obtained by employing only five inerters. © 2013 Elsevier Ltd.


Xu L.,Nanjing University of Information Science and Technology | Li X.,Nanjing University of Science and Technology
Journal of Crystal Growth | Year: 2010

In this work, Fe-doped ZnO thin films were prepared by sol-gel method on Si and glass substrates and influence of Fe-doping concentration on the structural and optical properties of the films was studied. The X-ray diffraction (XRD) analyses show that all the ZnO thin films prepared in this work have a hexagonal wurtzite structure and are preferentially oriented along the c-axis perpendicular to the substrate surface. After 1 at% Fe is doped, the crystalline quality and the preferential orientation of ZnO thin film are improved. However, when Fe-doping concentration is above 1 at%, the crystalline quality and the preferential orientation of ZnO thin film is weakened in turn. The surface morphology analyses of the samples show that the ZnO grain sizes tend to decrease with the increase of Fe-doping concentration. Fe-incorporation hardly influences the transmittance in the visible range, but the optical band-gaps of ZnO thin films gradually increase with the improved Fe-doping concentration. The photoluminescence spectra display that all the samples have an ultraviolet emission peak centered at 381 nm and the 1 at% Fe-doped ZnO thin film has the strongest ultraviolet emission peak. The above results suggest that 1 at% Fe-incorporation can improve the crystalline quality and enhance the ultraviolet emission of ZnO thin film. © 2009 Elsevier B.V. All rights reserved.


Xu L.,Nanjing University of Information Science and Technology | Zheng G.,Nanjing University of Information Science and Technology | Miao J.,Nanjing University of Information Science and Technology | Xian F.,Nanjing University of Science and Technology
Applied Surface Science | Year: 2012

In this work, ZnO thin films were prepared by sol-gel method and the dependence of structural and optical properties of these films on sol concentrations was deeply investigated. Unlike the previous studies, the ZnO thin films deposited in this study have approximately equal thickness, which excludes the influence of film thickness on the physical properties. The results show that low sol concentration is favorable for obtaining high c-axis oriented ZnO thin films with good crystalline quality. When the sol concentration is above 0.7 mol/L, the degree of c-axis orientation of ZnO thin films decreases and the optical quality is also degraded. Photoluminescence spectra indicate that the defect-related blue emission is increased with the enhancement of sol concentration. The mechanism of the blue emission is analyzed. The reason why high sol concentration is unfavorable for formation of high c-axis oriented ZnO thin films and obtaining high optical quality is also discussed. © 2012 Elsevier B.V. All rights reserved.


Ma Q.,Nanjing University of Science and Technology | Wang Z.,Shandong University of Science and Technology | Miao G.,Nanjing University of Information Science and Technology
Journal of the Franklin Institute | Year: 2014

This paper addresses the group consensus problem of second-order nonlinear multi-agent systems through leader-following approach and pinning control. The network topology is assumed to be directed and weakly connected. The pinning consensus protocol is designed according to the agent property, that is, the inter-act agent and the intra-act agent. Some consensus criteria are proposed to guarantee that the agents asymptotically follow the virtual leader in each group, while agents in different groups behave independently. Numerical example is also provided to demonstrate the effectiveness of the theoretical analysis. © 2013 The Franklin Institute. Published by Elsevier Ltd. All right sreserved.


Wang X.,Nanjing University of Science and Technology | Wang X.,University of Illinois at Urbana - Champaign | Bian G.,University of Illinois at Urbana - Champaign | Miller T.,University of Illinois at Urbana - Champaign | Chiang T.-C.,University of Illinois at Urbana - Champaign
Physical Review Letters | Year: 2012

Topological surface states are protected against local perturbations, but this protection does not extend to chemical reaction over the whole surface, as demonstrated by theoretical studies of the oxidation of Bi 2Se 3 and its effects on the surface spin polarization and current. While chemisorption of O 2 largely preserves the topological surface states, reaction with atomic O removes the original surface states and yields two new sets of surface states. One set forms a regular Dirac cone but is topologically trivial. The other set, while topologically relevant, forms an unusual rounded Dirac cone. The details are governed by the hybridization interaction at the interface. © 2012 American Physical Society.


Bian G.,University of Illinois at Urbana - Champaign | Wang X.,University of Illinois at Urbana - Champaign | Wang X.,Nanjing University of Science and Technology | Liu Y.,University of Illinois at Urbana - Champaign | And 2 more authors.
Physical Review Letters | Year: 2012

Spin-polarized gapless surface states in topological insulators form chiral Dirac cones. When such materials are reduced to thin films, the Dirac states on the two faces of the film can overlap and couple by quantum tunneling, resulting in a thickness-dependent insulating gap at the Dirac point. Calculations for a freestanding Sb film with a thickness of four atomic bilayers yield a gap of 36 meV, yet angle-resolved photoemission measurements of a film grown on Si(111) reveal no gap formation. The surprisingly robust Dirac cone is explained by calculations in terms of interfacial interaction. © 2012 American Physical Society.


Xie Y.,Shanghai Dianji University | Feng Y.,Nanjing University of Science and Technology | Qiu Y.,Nanjing University of Science and Technology
Renewable Energy | Year: 2013

Wind energy has been identified in China as an important alternative energy source to balance its energy mix. By the end of 2012, wind power (2%) has surpassed nuclear power to become China's 3rd largest energy resource of electricity, only behind thermal power and hydropower. The rapid growth of China wind power industry in recent years has made China become the biggest market in the world. Meanwhile, it has created a big market for educational institutions to provide wind energy related education and training. The main objective of this study is to review current wind energy education and training in Chinese universities and training centers. Most of wind energy courses are provided by public universities because they have been accredited by Ministry of Education of China to offer students different options, including full-time and part-time degrees in Bachelor, Master or Ph.D. On-the-job training also has tremendous demand from the professionals who prefer short-term courses or on-site courses. Generally, the development of wind energy education and training lags behind the growth of wind power industry. Our study highlights the major opportunities and future challenges in China wind energy education and training. © 2013 Elsevier Ltd.


Zhang S.,Japan National Institute of Materials Science | Zhang S.,Nanjing University of Science and Technology | Yang X.,Japan National Institute of Materials Science | Qin C.,Japan National Institute of Materials Science | And 3 more authors.
Journal of Materials Chemistry A | Year: 2014

Dye-sensitized solar cells as "low-cost" alternatives to traditional silicon-based solar cells are promising for clean electricity generation. The key processes in practical devices, such as generation, collection, and recombination of charges that greatly affect the cell performance, occur at interfaces and are influenced by properties of the interfacial materials. In this article, we summarize recent progress of materials and technologies associated with the functionalization of interfaces to significantly improve DSCs' performance, emphasizing greatly the most important semiconductor/dye/electrolyte interface where major energy conversion and charge transfer processes occur. Finally, the prospects of interfacial engineering for highly efficient dye-sensitized solar cells are highlighted in the outlook. © 2014 the Partner Organisations.


Xu Z.,Shanghai JiaoTong University | Xu Z.,Nanjing University of Science and Technology | Yager R.R.,The College of New Rochelle
IEEE Transactions on Fuzzy Systems | Year: 2010

The power-average (PA) operator and the power-ordered-weighted-average (POWA) operator are the two nonlinear weighted-average aggregation tools whose weighting vectors depend on the input arguments. In this paper, we develop a power-geometric (PG) operator and its weighted form, which are on the basis of the PA operator and the geometric mean, and develop a power-ordered-geometric (POG) operator and a power-ordered-weighted-geometric (POWG) operator, which are on the basis of the POWA operator and the geometric mean, and study some of their properties. We also discuss the relationship between the PA and PG operators and the relationship between the POWA and POWG operators. Then, we extend the PG and POWG operators to uncertain environments, i.e., develop an uncertain PG (UPG) operator and its weighted form, and an uncertain power-ordered-weighted-geometric (UPOWG) operator to aggregate the input arguments taking the form of interval of numerical values. Furthermore, we utilize the weighted PG and POWG operators, respectively, to develop an approach to group decision making based on multiplicative preference relations and utilize the weighted UPG and UPOWG operators, respectively, to develop an approach to group decision making based on uncertain multiplicative preference relations. Finally, we apply both the developed approaches to broadband Internet-service selection. © 2006 IEEE.


Chambers S.A.,Pacific Northwest National Laboratory | Droubay T.C.,Pacific Northwest National Laboratory | Capan C.,Washington State University | Sun G.Y.,Nanjing University of Science and Technology
Surface Science | Year: 2012

We show that the HF acid etch commonly used to prepare SrTiO 3(001) for heteroepitaxial growth of complex oxides results in a non-negligible level of F doping within the terminal surface layer of TiO 2. Using a combination of x-ray photoelectron spectroscopy and scanned angle x-ray photoelectron diffraction, we determine that on average ∼ 13% of the O anions in the surface layer are replaced by F, but that F does not occupy O sites in deeper layers. Despite this perturbation to the surface, the Fermi level remains unpinned, and the surface-state density, which determines the amount of band bending, is driven by factors other than F doping. The presence of F at the STO surface is expected to result in lower electron mobilities at complex oxide heterojunctions involving STO substrates because of impurity scattering. Unintentional F doping can be substantially reduced by replacing the HF-etch step with a boil in deionized water, which in conjunction with an oxygen tube furnace anneal, leaves the surface flat and TiO 2 terminated. © 2011 Elsevier B.V. All rights reserved.


Ma Q.,Nanjing University of Science and Technology | Miao G.,Nanjing University of Information Science and Technology
Neurocomputing | Year: 2014

This paper investigates the distributed containment control problem for linear multi-agent systems. Distributed dynamic output feedback controllers on the basis of the relative outputs of neighboring agents are proposed. Necessary and sufficient containment control conditions are presented which are less conservative than those in the literature. These conditions depend on the spectral properties of the topology matrix. Effective algorithms are proposed to obtain control gain matrices based on H∞ type Riccati design. Then, distributed static output feedback control method is also discussed. Simulation examples are provided finally to demonstrate the effectiveness of the proposed design methods. © 2014 Elsevier B.V.


Xu L.,Nanjing University of Science and Technology | Nallanathan A.,King's College London
IEEE Journal on Selected Areas in Communications | Year: 2016

In this paper, an energy-efficient resource allocation problem is modeled as a chance-constrained programming for multicast cognitive orthogonal frequency division multiplexing (OFDM) network. The resource allocation is subject to constraints in service quality requirements, total power, and probabilistic interference constraint. The statistic channel state information (CSI) between cognitive-based station (CBS) and primary user (PU) is adopted to compute the interference power at the receiver of PU, and we develop an energy-efficient chance-constrained subcarrier and power allocation algorithm. Support vector machine (SVM) is employed to compute the probabilistic interference constraint. Then, the chance-constrained resource allocation problem is transformed into a deterministic resource allocation problem, and Zoutendijk's method of feasible direction is utilized to solve it. Simulation results demonstrate that the proposed algorithm not only achieves a tradeoff between energy efficiency and satisfaction index, but also guarantees the probabilistic interference constraint very well. © 2016 IEEE.


Ge W.,Nanjing University of Science and Technology | Zhu X.,Nanjing University of Science and Technology | Zhu X.,Yancheng Institute of Technology | Wei Y.,Nanjing University of Science and Technology
European Journal of Organic Chemistry | Year: 2013

An aerobic CeCl3·7H2O/NaI-catalyzed C-H functionalization reaction was developed for the synthesis of 3-sulfenylimidazo[1,2-a]pyridines from easily available ketones, 2-aminopyridines, and disulfides without DMSO or peroxide as an oxidant. This three-component tandem reaction process involves the formation of imidazo[1,2-a]pyridines followed by Friedel-Crafts sulfenylation in one pot under mild conditions. Both aryl and alkyl ketones afforded the desired products in good to excellent yields without the presence of other additives. Aerobic oxidative three-component tandem formation of C-N and C-S bonds in one-pot! A CeCl3·7H2O/NaI system is efficient for the synthesis of 3-sulfenylimidazo[1,2-a]pyridines through a C-H functionalization strategy. Without the use of disulfides, a variety of imidazo[1,2-a]pyridines are obtained in good yields by using this protocol. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Feng Y.,Nanjing University of Science and Technology | Qiu Y.,Nanjing University of Science and Technology | Crabtree C.J.,Durham University | Long H.,University of Sheffield | Tavner P.J.,Durham University
Wind Energy | Year: 2013

Concerns amongst wind turbine (WT) operators about gearbox reliability arise from complex repair procedures, high replacement costs and long downtimes leading to revenue losses. Therefore, reliable monitoring for the detection, diagnosis and prediction of such faults are of great concerns to the wind industry. Monitoring of WT gearboxes has gained importance as WTs become larger and move to more inaccessible locations. This paper summarizes typical WT gearbox failure modes and reviews supervisory control and data acquisition (SCADA) and condition monitoring system (CMS) approaches for monitoring them. It then presents two up-to-date monitoring case studies, from different manufacturers and types of WT, using SCADA and CMS signals.The first case study, applied to SCADA data, starts from basic laws of physics applied to the gearbox to derive robust relationships between temperature, efficiency, rotational speed and power output. The case study then applies an analysis, based on these simple principles, to working WTs using SCADA oil temperature rises to predict gearbox failure.The second case study focuses on CMS data and derives diagnostic information from gearbox vibration amplitudes and oil debris particle counts against energy production from working WTs.The results from the two case studies show how detection, diagnosis and prediction of incipient gearbox failures can be carried out using SCADA and CMS signals for monitoring although each technique has its particular strengths. It is proposed that in the future, the wind industry should consider integrating WT SCADA and CMS data to detect, diagnose and predict gearbox failures.Copyright © 2012 John Wiley & Sons, Ltd. Copyright © 2012 John Wiley & Sons, Ltd.


Yu D.-J.,Nanjing University of Science and Technology | Shen H.-B.,Shanghai JiaoTong University | Yang J.-Y.,Nanjing University of Science and Technology
Amino Acids | Year: 2012

Accurately predicting the transmembrane helices (TMH) in a helical membrane protein is an important but challenging task. Recent researches have demonstrated that statistics-based methods are promising routes to improve the TMH prediction accuracy. However, most of existing TMH predictors are parametric models and they have to make assumptions of several or even hundreds of adjustable parameters based on the underlying probability distribution, which is difficult when no a priori knowledge is available. Besides the performances of these parametric predictors significantly depend on the estimated parameters, some of them need to exploit the entire training dataset in the prediction stage, which will lead to low prediction efficiency and this problem will become even worse when dealing with large-scale dataset. In this paper, we propose a novel SOMPNN model for prediction of TMH that features by minimal parameter assumptions requirement and high computational efficiency. In the SOMPNN model, a self-organizing map (SOM) is used to adaptively learn the helices distribution knowledge hidden in the training data, and then a probabilistic neural network (PNN) is adopted to predict TMH segments based on the knowledge learned by SOM. Experimental results on two benchmark datasets show that the proposed SOMPNN outperforms most existing popular TMH predictors and is promising to be extended to deal with other complicated biological problems. The datasets and the source codes of SOMPNN are available at http://www.csbio.sjtu.edu.cn/bioinf/SOMPNN/ . © 2011 Springer-Verlag.


Song G.,Nanjing University of Science and Technology | Wang Z.,Shandong University of Science and Technology | Wang Z.,Nanjing University
Nonlinear Dynamics | Year: 2013

This paper is concerned with the problems of output feedback control for uncertain discrete time-delay systems with input saturation. The delay partitioning approach is proposed to obtain new stability criteria. The dynamic output feedback controller is designed based on a linear matrix inequality framework. A sufficient condition is developed, which guarantees the existence of dynamic output feedback controllers such that all trajectories of the closed-loop system starting from an admissible initial condition domain converge to a smaller ellipsoid. Simulation examples are provided to show the potential of the proposed techniques. © 2013 Springer Science+Business Media Dordrecht.


Hu J.,Zhejiang Ocean University | Li N.,Donghua University | Liu X.,Nanjing University of Science and Technology | Zhang G.,Nanjing University of Science and Technology
Nonlinear Dynamics | Year: 2013

This paper is concerned with the sampled-data state estimation problem for a class of delayed neural networks with Markovian jumping parameters. Unlike the classical state estimation problem, in our state estimation scheme, the sampled measurements are adopted to estimate the concerned neuron states. The neural network under consideration is assumed to have multiple modes that switch from one to another according to a given Markovian chain. By utilizing the input delay approach, the sampling period is converted into a time-varying yet bounded delay. Then a sufficient condition is given under which the resulting error dynamics of the neural networks is exponentially stable in the mean square. Based on that, a set of sampled-data estimators is designed in terms of the solution to a set of linear matrix inequalities (LMIs) which can be solved by using the available software. Finally, a numerical example is used to show the effectiveness of the estimation approach proposed in this paper. © 2013 Springer Science+Business Media Dordrecht.


Li X.-W.,Nanjing Southeast University | Li X.-W.,Nanjing University of Science and Technology | Zhang X.-S.,Nanjing Southeast University | Quan S.,China Wuzhou Engineering Corporation Ltd.
Applied Energy | Year: 2011

Liquid desiccant cooling system (LDCS) is a novel air-conditioning system with good energy saving potential. However, the present LDCS has a poor performance, mainly because the conventional thermal regeneration method wastes too much energy during the regeneration process. To improve that, photovoltaic-electrodialysis (PV-ED) regeneration method is introduced: it has a higher performance by using solar photovoltaic panels to drive an electrodialysis regeneration process. To further explore the PV-ED method, both single-stage and double-stage photovoltaic-electrodialysis regeneration systems are presented in this paper. Analysis is made on these two systems and some influential factors are investigated. It reveals that the concentration difference between the desiccant solution before and after regeneration has a strong impact on system performance. Moreover, comparison is conducted between the single-stage and the double-stage systems, the results show that the double-stage system is more energy-efficient and it can save more than 50% energy under optimized working conditions. © 2011 Elsevier Ltd.


Zhang D.,Linyi Normal University | Zhang D.,Nanjing University of Science and Technology | Yang H.,Linyi Normal University
Journal of Molecular Structure | Year: 2014

In this work, polyvinylpyrrolidone(PVP)-capped silver nanoparticles were synthesized using ethylene glycol as solvent and reducing agent through a simple, one-pot solvothermal method at 160 C. UV-vis spectroscopy, TEM and Raman spectra are used to characterize the PVP-capped silver nanoparticles. The results show that the formed silver nanoparticles are anisotropy with different size and morphology such as triangle, hexagon and pentagon. Moreover, the formation process of silver nanoparticles was discussed in detail. Furthermore, the formed silver nanoparticles displayed high surface-enhanced Raman scattering effects. © 2013 Elsevier B.V. All rights reserved.


Ma Q.,Nanjing University of Science and Technology | Wang Z.,Shandong University of Science and Technology | Lu J.,Nanjing Normal University
Nonlinear Dynamics | Year: 2012

The finite-time synchronization problem of a class of complex dynamical networks with time-varying delays is addressed in this paper. The network topology is assumed to be directed and weakly connected. By introducing a special zero row-sum matrix and combining the Lyapunov-Krasovskii functional method and the Kronecker product technique, a sufficient condition is presented, which consist of two simple low-dimensional matrix inequalities. Illustrative example is given to show the feasibility of the proposed method. © 2012 Springer Science+Business Media B.V.


Wang Z.,Nanjing University of Science and Technology | Wang Z.,Shandong University of Science and Technology | Huang X.,Shandong University of Science and Technology | Shen H.,Anhui University of Technology
Neurocomputing | Year: 2012

This paper addresses the design of sliding mode controller (SMC) for an uncertain chaotic fractional order economic system. A new fraction-integer integral switching surface is constructed to facilitate stability analysis of the closed-loop system. A sliding mode controller is developed to guarantee that sliding mode motion exists on every point of the switching surface and any state outside the surface is driven to reach the surface in a finite time. Moreover, an adaptive SMC is designed in the case that the upper bound of the uncertainties is unknown. Numerical simulations are performed to verify the feasibility and effectiveness of the proposed controllers. © 2011 Elsevier B.V.


Cheng Q.,Nanjing Southeast University | Zhang X.-S.,Nanjing Southeast University | Li X.-W.,Nanjing Southeast University | Li X.-W.,Nanjing University of Science and Technology
Energy and Buildings | Year: 2012

Photovoltaic-electrodialysis (PV-ED) regeneration is a novel method for liquid desiccant cooling system (LDCS), which has a higher performance than the conventional thermal regeneration method by using solar photovoltaic components to drive an electrodialysis regeneration process. However, there are many defects in the previous proposed single-stage PV-ED system. In this paper, a new double-stage photovoltaic/thermal ED regeneration system is presented. Analysis of the performances of the single-stage and double-stage regeneration system is made and the influential factors are investigated. It reveals that the double-stage PVT-ED regeneration system is more applicable than the single-stage PV-ED regeneration system for liquid desiccant cooling system. Moreover, comparisons between the single-stage system and the double-stage system show that the double-stage system is more energy efficient than the single-stage system under the optimized working conditions. © 2012.


Yin J.,Nanjing University of Science and Technology | Liu Z.,Nanjing University of Science and Technology | Jin Z.,Nanjing University of Science and Technology | Yang W.,Nanjing Southeast University
Neurocomputing | Year: 2012

Sparse representation has attracted great attention in the past few years. Sparse representation based classification (SRC) algorithm was developed and successfully used for classification. In this paper, a kernel sparse representation based classification (KSRC) algorithm is proposed. Samples are mapped into a high dimensional feature space first and then SRC is performed in this new feature space by utilizing kernel trick. Since samples in the high dimensional feature space are unknown, we cannot perform KSRC directly. In order to overcome this difficulty, we give the method to solve the problem of sparse representation in the high dimensional feature space. If an appropriate kernel is selected, in the high dimensional feature space, a test sample is probably represented as the linear combination of training samples of the same class more accurately. Therefore, KSRC has more powerful classification ability than SRC. Experiments of face recognition, palmprint recognition and finger-knuckle-print recognition demonstrate the effectiveness of KSRC. © 2011 Elsevier B.V.


Zuo X.-B.,Nanjing University of Science and Technology | Li A.-Q.,Nanjing Southeast University
Structural Control and Health Monitoring | Year: 2011

This paper estimates the effectiveness of shape memory alloy (SMA) damper on cable vibration mitigation by numerical simulation and experimental investigation. First, a simplified constitutive law of superelastic SMA and the structure of the SMA damper developed by superelastic SMA wires are presented. Second, based on Hamilton principle and Galerkin method, the vibration equations for a cable-SMA damper system are established, and numerical solutions of which are adopted to obtain the dynamic responses of the system without and with SMA damper using the Newmark-β method. Finally, numerical simulation associated with a practical cable and experiments on a scaled test cable are, respectively, carried out to investigate the effectiveness of SMA damper on the vibration mitigation of the cable subjected to the free and forced vibration. Numerical simulations indicate that the SMA damper developed can clearly shorten the free vibration decay time of the cable and increase the equivalent damping ratios of the cable with the reasonable parameter and location of SMA damper, and that it can decrease the displacement response amplitude when the cable is subjected to white-noise excitations. The experimental results show that the SMA damper can reduce the acceleration response of the test cable under free vibration and forced vibration induced by the deck motion. As a result, the SMA damper developed is very effective for mitigating cable vibration. Copyright © 2009 John Wiley & Sons, Ltd.


Huang H.,Rice University | Huang H.,Nanjing University of Science and Technology | Yang S.,Rice University | Yang S.,Beihang University | And 3 more authors.
Advanced Materials | Year: 2014

Homogeneous dispersion of ultrafine Pt nanoparticles on 3D architectures constructed of graphene and exfoliated graphitic carbon nitride results in hybrids with 3D porous structures, large surface area, high nitrogen content, and good electrical conductivity. This leads to excellent electrocatalytic activity, unusually high poison tolerance, and reliable stability for methanol oxidation, making them of interest as catalysts in direct methanol fuel cells. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Ding S.-N.,Nanjing Southeast University | Gao B.-H.,Nanjing Southeast University | Shan D.,Nanjing University of Science and Technology | Sun Y.-M.,Nanjing Southeast University | Cosnier S.,CNRS Molecular Chemistry Department
Biosensors and Bioelectronics | Year: 2013

Electrochemiluminescence (ECL) of TiO 2 nanocrystals with different crystal styles modified fluorine-doped tin oxide (FTO) electrode was investigated in H 2O 2 solution. The amorphous TiO 2 nanospheres were facilely synthesized by the hydrothermal and condensation method. Crystal TiO 2, namely anatase and rutile, were prepared by calcination of the amorphous TiO 2 nanospheres at 450 and 800°C, respectively. The transmission electron microscope (TEM) and electron diffraction pattern were used to characterize the obtained TiO 2 nanoparticles morphology and the corresponding crystal styles. The electrochemical and ECL behaviors were investigated by cyclic voltammetry. The ECL quenching was observed by introduction of gold nanoparticles. Based on the quenching effect, a sensitive glucose ECL biosensor as a model was fabricated by in-situ growing-up gold seeds in AuCl 4 - solution induced by biologically generated H 2O 2. The linear range to detect glucose is from 5.0×10 -7M to 4.0×10 -3M with the limit of detection of 2.5×10 -7M. © 2012 Elsevier B.V..


Chen G.,Nanjing University of Science and Technology | Zhang W.,Nanjing Southeast University
IEEE Transactions on Industrial Electronics | Year: 2016

The paper describes application of unmanned robot applied to automotive test (URAT) to save time, costs, and to improve accuracy of tests. A hierarchical coordinated control method based on fuzzy logic theory is proposed for URAT, to realize the coordinated control and the accurate speed tracking of driving test cycle during all kinds of conditions. The system structure is briefly described in the paper. Similar to a skilled human driver, a control method based on Saridis hierarchical architecture to coordinate multiple robot manipulators systems for the automotive test system is presented. The coordinated movements for throttle mechanical leg, clutch mechanical leg, brake mechanical leg are designed. On top of that, the fuzzy speed controller for URAT is used to accurately track the desired vehicle velocity under different test conditions. Experiments have been conducted by using a Ford FOCUS car. The proposed control method of URAT is experimentally proved and compared with other control methods and with human driver performances. © 1982-2012 IEEE.


Gleiter H.,Karlsruhe Institute of Technology | Gleiter H.,Nanjing University of Science and Technology
Beilstein Journal of Nanotechnology | Year: 2013

Nanoglasses are a new class of noncrystalline solids. They differ from today's glasses due to their microstructure that resembles the microstructure of polycrystals. They consist of regions with a melt-quenched glassy structure connected by interfacial regions, the structure of which is characterized (in comparison to the corresponding melt-quenched glass) by (1) a reduced (up to about 10%) density, (2) a reduced (up to about 20%) number of nearest-neighbor atoms and (3) a different electronic structure. Due to their new kind of atomic and electronic structure, the properties of nanoglasses may be modified by (1) controlling the size of the glassy regions (i.e., the volume fraction of the interfacial regions) and/or (2) by varying their chemical composition. Nanoglasses exhibit new properties, e.g., a Fe90Sc10 nanoglass is (at 300 K) a strong ferromagnet whereas the corresponding melt-quenched glass is paramagnetic. Moreover, nanoglasses were noted to be more ductile, more biocompatible, and catalytically more active than the corresponding melt-quenched glasses. Hence, this new class of noncrystalline materials may open the way to technologies utilizing the new properties. © 2013 Gleiter; licensee Beilstein-Institut.


Zhang D.,Linyi Normal University | Zhang D.,Nanjing University of Science and Technology | Zou W.,Nanjing University of Science and Technology
Current Applied Physics | Year: 2013

In this paper, a composite of reduced graphene oxide decorated by Co 3O4 hollow spheres (Co3O4/RGO composite) has been synthesized by a one-pot solvothermal method. The samples are characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR), Raman spectra and so on. The results demonstrate that the Co3O4 hollow spheres with good purity and homogenous size are absorbed onto the reduced graphene oxide sheets as spacers to prevent the aggregation of the graphene oxide sheets. Furthermore, the well electrochemical properties demonstrate that the Co3O 4/RGO composite might have potential applications as electrode materials for supercapacitors. © 2013 Elsevier Ltd. All rights reserved.


Lin X.,Nanjing Agricultural University | Lin X.,Nanjing University of Science and Technology | Du H.,Nanjing Southeast University | Li S.,Nanjing Southeast University | Zou Y.,Nanjing University of Science and Technology
IET Control Theory and Applications | Year: 2013

Finite-time stability and finite-time boundedness for a class of switched linear systems with time-varying delay are studied. Sufficient conditions which guarantee switched linear systems with time-varying delay finite-time stable or finite-time bounded are presented. These conditions are delay-dependent and are given in terms of linear matrix inequalities. Average dwell time of switching signals is also given such that switched linear systems are finite-time stable or finite-time bounded. Moreover, finite-time weighted L2-gain of switched linear systems with time-varying delay are also given to measure its disturbance tolerance capability in the fixed time interval. Detail proofs are accomplished by using multiple Lyapunov-like functions. An example is employed to verify the efficiency of the proposed method. © 2013 The Institution of Engineering and Technology.


Xu J.,Northwestern Polytechnical University | Xu J.,Nanjing University of Science and Technology | Xu J.,Nanjing Southeast University
IEEE Transactions on Circuits and Systems for Video Technology | Year: 2016

This later firstly presents a quasi-elliptic bandpass filter (QE-BPF) which consists of a pair of shorted stepped-impedance resonator (SSIR) and a dual-mode resonator (DMR). Then, a 900 MHz switchable bandpass filter (SW-BPF) and a 1250 MHz SW-BPF are designed by loading p-i-n diodes at two open ends of DMR or SSIRs. Finally, a common-T junction constructed by two T-networks is used to combine the above designed 900 and 1250 MHz SW-BPFs to constitute a switchable diplexer. The fabricated QE-BPF, two SW-BPFs and switchable diplexer exhibit wide bandwidth, low insertion loss, sharp passband selectivity, high port isolation and compact size. © 2015 IEEE.


Yao J.,Nanjing University of Science and Technology | Deng W.,Beihang University | Jiao Z.,Beihang University
IEEE Transactions on Industrial Electronics | Year: 2015

This paper concerns high-accuracy tracking control for hydraulic actuators with nonlinear friction compensation. Typically, LuGre model-based friction compensation has been widely employed in sundry industrial servomechanisms. However, due to the piecewise continuous property, it is difficult to be integrated with backstepping design, which needs the time derivation of the employed friction model. Hence, nonlinear model-based hydraulic control rarely sets foot in friction compensation with nondifferentiable friction models, such as LuGre model, Stribeck effects, although they can give excellent friction description and prediction. In this paper, a novel continuously differentiable nonlinear friction model is first derived by modifying the traditional piecewise continuous LuGre model, then an adaptive backstepping controller is proposed for precise tracking control of hydraulic systems to handle parametric uncertainties along with nonlinear friction compensation. In the formulated nonlinear hydraulic system model, friction parameters, servovalve null shift, and orifice-type internal leakage are all uniformly considered in the proposed controller. The controller theoretically guarantees asymptotic tracking performance in the presence of parametric uncertainties, and the robustness against unconsidered dynamics, as well as external disturbances, is also ensured via Lyapunov analysis. The effectiveness of the proposed controller is demonstrated via comparative experimental results. © 1982-2012 IEEE.


Chen G.,Nanjing University of Science and Technology | Zhang W.-G.,Nanjing Southeast University
Robotics and Computer-Integrated Manufacturing | Year: 2015

The digital prototyping design of electromagnetic unmanned robot applied to automotive test (URAT) is presented in this paper. The electromagnetic URAT adopts electromagnetic linear motor (EMLM) as its drive mechanism. The three-dimensional simulation model of electromagnetic URAT is established. And the kinematics simulation and dynamics simulation of electromagnetic URAT is conducted. The displacement, speed and force of shift mechanical arm, throttle mechanical leg, brake mechanical leg and clutch mechanical leg are obtained. Using the finite element method (FEM), the structure and material of key components of electromagnetic URAT are checked. The automatic driving simulation of electromagnetic URAT is conducted. Experiments are performed using a Ford FOCUS car. Simulation and experiment results demonstrate the effectiveness of the proposed prototyping of electromagnetic URAT system. © 2014 Elsevier Ltd. All rights reserved.


Wang W.,Nanjing University of Science and Technology | Cao Y.,Tianjin Normal University
International Journal of Energy Research | Year: 2013

Chemical-looping ethanol reforming with carbon dioxide capture is proposed. It combines chemical-looping reforming and carbon dioxide capture for pure hydrogen generation from ethanol with inherent separation of carbon dioxide. A thermal analysis of the process using NiO oxygen carrier is performed by simulating reactions using the Gibbs energy minimization method. The promising systems are investigated further with respect to temperature, NiO/C2H5OH molar ratio, CaO/C2H5OH molar ratio and pressure changes as well as possible carbon formation in the reformer. Favorable operation conditions in the presence of CaO are: pressures around 3 atm, reactor temperatures around 850 K, NiO/C2H5OH molar ratio=3 and CaO/C2H5OH=3. The H2 yield and thermal efficiency with CaO addition are higher than that without CaO addition, showing that the addition of a CO2 sorbent in the process increases the H2 production. © 2012 John Wiley & Sons, Ltd.


Yao J.,Nanjing University of Science and Technology | Jiao Z.,Beihang University | Ma D.,Nanjing University of Science and Technology | Yan L.,Beihang University
IEEE/ASME Transactions on Mechatronics | Year: 2014

Structured and unstructured uncertainties are the main obstacles in the development of advanced controllers for high-accuracy tracking control of hydraulic servo systems. For the structured uncertainties, nonlinear adaptive control can be employed to achieve asymptotic tracking performance. But modeling errors, such as nonlinear frictions, always exist in physical hydraulic systems and degrade the tracking accuracy. In this paper, a robust integral of the sign of the error controller and an adaptive controller are synthesized via backstepping method for motion control of a hydraulic rotary actuator. In addition, an experimental internal leakage model of the actuator is built for precise model compensation. The proposed controller accounts for not only the structured uncertainties (i.e., parametric uncertainties), but also the unstructured uncertainties (i.e., nonlinear frictions). Furthermore, the controller theoretically guarantees asymptotic tracking performance in the presence of various uncertainties, which is very important for high-accuracy tracking control of hydraulic servo systems. Extensive comparative experimental results are obtained to verify the high-accuracy tracking performance of the proposed control strategy. © 2013 IEEE.


Yao J.,Nanjing University of Science and Technology | Jiao Z.,Beihang University | Ma D.,Nanjing University of Science and Technology
IEEE Transactions on Industrial Electronics | Year: 2014

In this paper, an output feedback nonlinear control is proposed for a hydraulic system with mismatched modeling uncertainties in which an extended state observer (ESO) and a nonlinear robust controller are synthesized via the backstepping method. The ESO is designed to estimate not only the unmeasured system states but also the modeling uncertainties. The nonlinear robust controller is designed to stabilize the closed-loop system. The proposed controller accounts for not only the nonlinearities (e.g., nonlinear flow features of servovalve), but also the modeling uncertainties (e.g., parameter derivations and unmodeled dynamics). Furthermore, the controller theoretically guarantees a prescribed tracking transient performance and final tracking accuracy, while achieving asymptotic tracking performance in the absence of time-varying uncertainties, which is very important for high-accuracy tracking control of hydraulic servo systems. Extensive comparative experimental results are obtained to verify the high-performance nature of the proposed control strategy. © 1982-2012 IEEE.


Zuo X.-B.,Nanjing University of Science and Technology | Sun W.,Nanjing Southeast University | Yu C.,Nanjing Southeast University
Construction and Building Materials | Year: 2012

In order to evaluate numerically the volumetric expansion of concrete under sulfate attack, models are proposed to calculate the expansive volume strain of concrete exposed to sulfate solutions. Firstly, a one-dimensional differential equation related to the diffusion-reaction behavior of sulfate ions in concrete is presented; secondly, based on chemical reactions between sulfate and calcium aluminates in concrete, the expansive volume strain caused by ettringite growth is obtained; thirdly, numerical analysis is carried out to investigate the volume expansion of concrete when it is exposed in sulfate solutions. Numerical results provide the evolution response of concrete volume expansion with the diffusion time, sulfate concentration, and calcium aluminates dissipation. © 2012 Elsevier Ltd. All rights reserved.


Yao J.,Nanjing University of Science and Technology | Jiao Z.,Beihang University | Ma D.,Nanjing University of Science and Technology
IEEE Transactions on Industrial Electronics | Year: 2014

Structured and unstructured uncertainties always exist in physical servo systems and degrade their tracking accuracy. In this paper, a practical method named adaptive robust control with extended state observer (ESO) is synthesized for high-accuracy motion control of a dc motor. The proposed controller accounts for not only the structured uncertainties (i.e., parametric uncertainties) but also the unstructured uncertainties (i.e., nonlinear friction, external disturbances, and/or unmodeled dynamics). Adaptive control for the structured uncertainty and ESO for the unstructured uncertainty are designed for compensating them respectively and integrated together via a feedforward cancellation technique. The global robustness of the controller is guaranteed by a feedback robust law. Furthermore, the controller theoretically guarantees a prescribed tracking performance in the presence of various uncertainties, which is very important for high-accuracy control of motion systems. Extensive comparative experimental results are obtained to verify the high-performance nature of the proposed control strategy. © 1982-2012 IEEE.


Yao J.,Nanjing University of Science and Technology | Jiao Z.,Beihang University | Ma D.,Nanjing University of Science and Technology
IEEE Transactions on Industrial Electronics | Year: 2014

Continuous friction compensation along with other modeling uncertainties is concerned in this paper, to result in a continuous control input, which is more suitable for controller implementation. To accomplish this control task, a practical method, named as robust integral of the sign of the error controller, is synthesized with a continuous differentiable friction model for high-accuracy motion control of a dc motor. To reduce the noise sensitivity and further improve the tracking accuracy, a desired compensation technique is employed in the proposed controller, in which the model compensation term depends on the reference trajectory only, and its global stability is guaranteed by a proper robust feedback law. Furthermore, the proposed controller theoretically guarantees an asymptotic output tracking performance even in the presence of modeling uncertainties, which is very important for high-accuracy control of motion systems. Comparative experimental results are obtained for the motion control of a dc motor drive system to verify the high-performance nature of the proposed control strategy. © 2014 IEEE.


Wang Z.,Nanjing University of Science and Technology | Wang Z.,Shandong University of Science and Technology | Huang X.,Shandong University of Science and Technology | Shi G.,Changzhou University
Computers and Mathematics with Applications | Year: 2011

In this paper, a delayed fractional order financial system is proposed and the complex dynamical behaviors of such a system are discussed by numerical simulations. A great variety of interesting dynamical behaviors of such a system including single-periodic, multiple-periodic, and chaotic motions are displayed. In particular, the effect of time delay on the chaotic behavior is investigated, it is found that an approximate time delay can enhance or suppress the emergence of chaos. Meanwhile, corresponding to different values of delay, the lowest orders for chaos to exist in the delayed fractional order financial systems are determined, respectively. © 2011 Elsevier Ltd. All rights reserved.


Chen S.,Nanjing University of Science and Technology | Zhu J.,Nanjing University of Science and Technology | Qiu L.,Monash University | Li D.,Monash University | Wang X.,Nanjing University of Science and Technology
Chemistry - A European Journal | Year: 2013

The development of novel nanostructured electrode materials with high performance and based on abundant elements is a key element in the societal pursuit of sustainable energy. Graphene-based structures with rich macroporosity and high conductive networks are promising components to develop novel electrode materials. Herein, we described a facile procedure to confine Ni(OH)2 particles in a graphene film, leading to a new sandwich-like hybrid structure. The hybrid film offers simultaneously ordered ion diffusion channels and high electrical conductivity, which facilitate the improvement of both electrode kinetics and electrochemical stability, thus leading to high capacitance, fast rate capability, and stable cycle life as supercapacitor materials. This work provides a facile pathway for optimized structures for electrode materials, and represents a benefit for the global issues of energy shortage and environmental pollution. Sandwich-like structures: Confinement of Ni(OH)2 particles in a graphene film has resulted in a new sandwich-like structure with excellent electrode kinetics and electrochemical stability. This system is a promising candidate for supercapacitor materials (see figure). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Xu Z.,Nanjing Southeast University | Xu Z.,Nanjing University of Science and Technology
IEEE Transactions on Fuzzy Systems | Year: 2012

We investigate multiattribute decision-making problems, where the attribute values are intuitionistic fuzzy values, and the weight information on attributes cannot be known completely. We first define the concepts of the overall attribute ideal solution and the overall attribute negative ideal solution of alternatives. Based on these two solutions, we define the satisfaction degree of each alternative. After that, we establish a multiobjective optimization model and then transform it into a single-objective optimization model. Furthermore, we establish an interactive method for multiattribute decision making with intuitionistic fuzzy information. A numerical example is also given to illustrate the solution processes of our methods. Finally, the extended results in interval-valued intuitionistic fuzzy situations are also pointed out. © 2012 IEEE.


Zheng L.,Nanjing University of Science and Technology | Zheng S.,Zhejiang University of Finance and Economics | Zhai Q.,Chaohu University
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2015

In this paper a lattice Boltzmann equation (LBE) method is designed that is different from the previous LBE for the Cahn-Hilliard equation (CHE). The starting point of the present CHE LBE model is from the kinetic theory and the work of Lee and Liu [T. Lee and L. Liu, J. Comput. Phys. 229, 8045 (2010)JCTPAH0021-999110.1016/j.jcp.2010.07.007]; however, because the CHE does not conserve the mass locally, a modified equilibrium density distribution function is introduced to treat the diffusion term in the CHE. Numerical simulations including layered Poiseuille flow, static droplet, and Rayleigh-Taylor instability have been conducted to validate the model. The results show that the predictions of the present LBE agree well with the analytical solution and other numerical results. © 2015 American Physical Society.


Li X.-W.,Nanjing University of Science and Technology | Li X.-W.,Nanjing Southeast University | Zhang X.-S.,Nanjing Southeast University
Energy Conversion and Management | Year: 2012

Absorption air-conditioning system has many priorities over vapor compression air-conditioning system as absorption system is more environment-friendly, capable of utilizing low grade heat and less dependent on the electric power. However, because of the low efficiency of energy usage, the performance of absorption system is not yet as competitive as vapor compression system. To improve that, a novel membrane absorption system is proposed in this paper: a regenerator consists of stacks with ion-exchange membranes, takes the places of the generator and the condenser; the electric energy gained from solar or wind power is utilized to drive this system. Primary analysis has been made, and the results show that this proposed membrane absorption air-conditioning system can raise its coefficient of performance as high as, or even higher than that of vapor compression system when the absorbent is LiBr solution, of which the mass concentration is below 52%, and the applied voltage is no more than 100 V. © 2011 Elsevier Ltd. All rights reserved.


Yao J.,Nanjing University of Science and Technology | Jiao Z.,Beihang University | Han S.,Beihang University
Chinese Journal of Aeronautics | Year: 2013

Low-velocity tracking capability is a key performance of flight motion simulator (FMS), which is mainly affected by the nonlinear friction force. Though many compensation schemes with ad hoc friction models have been proposed, this paper deals with low-velocity control without friction model, since it is easy to be implemented in practice. Firstly, a nonlinear model of the FMS middle frame, which is driven by a hydraulic rotary actuator, is built. Noting that in the low velocity region, the unmodeled friction force is mainly characterized by a changing-slowly part, thus a simple adaptive law can be employed to learn this changing-slowly part and compensate it. To guarantee the boundedness of adaptation process, a discontinuous projection is utilized and then a robust scheme is proposed. The controller achieves a prescribed output tracking transient performance and final tracking accuracy in general while obtaining asymptotic output tracking in the absence of modeling errors. In addition, a saturated projection adaptive scheme is proposed to improve the globally learning capability when the velocity becomes large, which might make the previous proposed projection-based adaptive law be unstable. Theoretical and extensive experimental results are obtained to verify the high-performance nature of the proposed adaptive robust control strategy. © 2013 Production and hosting by Elsevier Ltd. on behalf of CSAA & BUAA.


Li X.-W.,Nanjing University of Science and Technology | Li X.-W.,Nanjing Southeast University | Zhang X.-S.,Nanjing Southeast University | Wang F.,Nanjing University of Science and Technology
Energy and Buildings | Year: 2013

Liquid desiccant cooling system (LDCS) is an alternative air-conditioning system with promising energy-saving potential. To further explore the potential of LDCS, it is important to reveal the mass transfer mechanism of dehumidification process. The classical mass transfer model does well in theoretical analysis, but failed to explain the dehumidification reverse phenomenon in experiments. Therefore, this paper proposes a mass transfer model based on the kinetic theory for improvement. Through theoretical and experimental research, it proves the new model clearly describes the dehumidification mechanism and did better in predicting the dehumidification reverse phenomenon. This paper also gives a method through which we can get some important parameters of the new model from the mass transfer coefficient of the classical model. © 2013 Elsevier B.V.


Ding S.-N.,Nanjing Southeast University | Shan D.,Nanjing University of Science and Technology | Cosnier S.,CNRS Molecular Chemistry Department | Le Goff A.,CNRS Molecular Chemistry Department
Chemistry - A European Journal | Year: 2012

Ru being served: A pyrene-Ru/SWCNT nanohybrid was formed through noncovalent π-π stacking interactions (see figure). After oxidative treatment, the pyrene-Ru/SWCNT-functionalized Pt electrode achieved a highly reversible redox process and exhibited excellent electrogenerated chemiluminescence behavior. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Ding S.-N.,Nanjing Southeast University | Gao B.-H.,Nanjing Southeast University | Shan D.,Nanjing University of Science and Technology | Sun Y.-M.,Nanjing Southeast University | Cosnier S.,CNRS Molecular Chemistry Department
Chemistry - A European Journal | Year: 2012

Shining brightly: Several tens to hundreds of times enhanced solid-state electrochemiluminescence (ECL) of CdTe quantum dots (CdTe-QDs) was realized by combining them with TiO 2 nanoparticles. The mechanism was due to the synergetic effect between titania and CdTe-QDs during the ECL process in H 2O 2 solution (see scheme). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Xiong G.,Nanjing University of Science and Technology | Zhang S.,Nanjing University of Science and Technology | Liu Q.,Air Defense Forces Academy
Physica A: Statistical Mechanics and its Applications | Year: 2012

Although the multifractal singularity spectrum revealed the distribution of singularity exponent, it failed to consider the temporal information, therefore it is hard to describe the dynamic evolving process of non-stationary and nonlinear systems. In this paper, we aim for a multifractal analysis and propose a time-singularity multifractal spectrum distribution (TS-MFSD), which will hopefully reveal the spatial dynamic character of fractal systems. Similar to the Wigner-Ville time-frequency distribution, the time-delayed conjugation of fractal signals is selected as the windows function. Furthermore, the time-varying Holder exponent and the time-varying wavelet singularity exponent are deduced based on the instantaneous self-correlation fractal signal. The time-singularity exponent distribution i.e. TS-MFSD is proposed, which involves time-varying Hausdorff singularity spectrum distribution, time-varying large deviation multifractal spectrum and time-varying Legendre spectrum distribution, which exhibit the singularity exponent distribution of fractal signal at arbitrary time. Finally, we studied the algorithm of the TS-MFSD based on the wavelet transform module maxima method, analyzed and discussed the characteristic of TS-MFSD based on Devil Staircase signal, stochastic fractional motion and real sea clutter. © 2012 Elsevier B.V. All rights reserved.


News Article | February 15, 2017
Site: phys.org

Ellipsoid plot of (N5)6(H3O)3(NH4)4Cl at the 50% probability level. The occupancies of H3O+ (O1), H3O+ (O2), Clˉ, N5ˉ, and NH4+ are 1/12, 1/24, 1/24, 1/4, and 1/6, respectively. Credit: (c) Science (2017). DOI: 10.1126/science.aah3840 (Phys.org)—The pentazole molecule and its anion, cyclo-N - has proven elusive to researchers for almost a century. The pentazole anion is highly unstable and cannot be made in bulk. Researchers from Nanjing University of Science and Technology and the University of Science and Technology Liaoning have devised a synthesis of a salt containing the pentazole anion that is stable up to 117oC. Their report appears in Science. The pentazole and its anion have a sordid history, at least for molecules. Pentazole was thought to be isolated as an arylpentazole in 1915, but was disproven several years later. Then, in the 1950s, a group of researchers managed to identify pentazole as an intermediate for another reaction. Later researchers became interested in combining N + and N - as a possible alternative to hydrazine as rocket fuel. Many attempts have been made to isolate the pentazole anion by cleaving the carbon-nitrogen bond in an arylpentazole. However, these have proven unsuccessful because of the difficulties in selectively cleaving the carbon-nitrogen bond. The addition of electron donating groups at the ortho and para positions of the arene helped with selective cleavage. In the current study, Zhang et al. were able to selectively cleave the carbon-nitrogen bond of 3,5-dimethyl-4-hydroxyphenylpentazole and stabilize the resulting pentazole anion using ferrous bisglycinate, Fe(Gly) . The anion was isolated as part of a salt, (N ) (H O) (NH ) Cl (19% yield). The Fe(Gly) stabilizer also served as a mediator for m-chloroperbenzoic acid. The molecular conformation of the salt ions was determined using single-crystal x-ray diffraction analysis where the five nitrogen atoms in cylco-N - are co-planar and aromatic. The structure was confirmed using 1H and 15N NMR as well as infrared and Raman spectroscopy. Additional studies showed that the salt is remarkably thermally stable up to 117oC, which is attributed to the salt's hydrogen bonding arrangement. All of the ions in the salt apparently play a role in stabilizing the pentazole anion. When Zhang et al. removed Cl- or when they removed NH +, cyclo-N - decomposed. This research allows for the isolation and characterization of an elusive aromatic azole molecule, one that has been out of reach for chemists for many years, and according to the authors this ends the search for this elusive molecule. More information: Chong Zhang et al. Synthesis and characterization of the pentazolate anion-Nˉ in (N)(HO)(NH)Cl, Science (2017). DOI: 10.1126/science.aah3840 Abstract Pentazole (HN5), an unstable molecular ring comprising five nitrogen atoms, has been of great interest to researchers for the better part of a century. We report the synthesis and characterization of the pentazolate anion stabilized in a (N5)6(H3O)3(NH4)4Cl salt. The anion was generated by direct cleavage of the C–N bond in a multisubstituted arylpentazole using m-chloroperbenzoic acid and ferrous bisglycinate. The structure was confirmed by single-crystal x-ray diffraction analysis, which highlighted stabilization of the cyclo-N5ˉ ring by chloride, ammonium, and hydronium. Thermal analysis indicated the stability of the salt below 117°C on the basis of thermogravimetry-measured onset decomposition temperature.


Huang H.W.,CAS Shenyang Institute of Metal Research | Wang Z.B.,CAS Shenyang Institute of Metal Research | Lu J.,City University of Hong Kong | Lu K.,CAS Shenyang Institute of Metal Research | Lu K.,Nanjing University of Science and Technology
Acta Materialia | Year: 2015

By means of surface mechanical rolling treatment (SMRT), a gradient nanostructured (GNS) surface layer was formed on AISI 316L stainless steel. The mean grain size is ∼30 nm in the topmost surface layer and increases with depth. Tension-compression fatigue measurements were performed on the SMRT sample under the stress-controlled mode. In comparison with the coarse-grained sample, the fatigue strength of the SMRT sample is significantly enhanced in both the low- and high- cycling fatigue regimes. Meanwhile, the fatigue ratio is evidently elevated with an increasing tensile strength in the SMRT sample. The initiation and growth of cracks, the cyclic deformation behaviors, as well as effects of strength and residual stresses, have been investigated to clarify the fatigue mechanism of the SMRT sample. The results emphasized the GNS surface layer enhances the fatigue property by suppressing the initiation of cracks and accommodating a remarkable cyclic plastic strain amplitude. © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Wang D.,Nanjing University of Science and Technology | Che W.,Nanjing University of Science and Technology | Chang Y.,Nanjing University of Science and Technology | Chin K.-S.,Chang Gung University | Chow Y.L.,University of Waterloo
IEEE Antennas and Wireless Propagation Letters | Year: 2013

A novel compact low-profile frequency selective surface (FSS) with controllable triband characteristics is presented. The proposed FSS consists of a stacked periodic array of square loops and complementary apertures, respectively centered within a wire grid and an aperture grid, which can create three transmission poles and two transmission zeros. Controllable triband performance is achieved, allowing the FSS to transmit the signal at 4 GHz while reflecting the signals at 6 and 9.5 GHz. Due to the compact and low-profile structure, the designed FSS has a reduced sensitivity to the incident angle compared to traditional triband FSSs. An equivalent circuit model is proposed for predicting and analyzing the frequency characteristics of this structure. For demonstration, a prototype of the proposed FSS is fabricated and measured. Good agreement between the simulated and measured results is observed. © 2002-2011 IEEE.


Rong G.,Nanjing University of Science and Technology | Huang D.W.,Shenyang Ligong University | Yang M.C.,CAS Shenyang Institute of Metal Research
Theoretical and Applied Fracture Mechanics | Year: 2012

Ballistic tests are performed by shooting both tungsten fiber/bulk metallic glass W/Zr 58Ti 13Cu 17Ni 12 composite rods (composite rod) and tungsten heavy alloy rods (95W rod) into 30CrMnMo target. The composite rod exhibits self-sharpening behaviors, and its matrix damages and fibers break are limited in a thin, narrow area, which is defined as " edge layer" Penetrating depth of composite rods is 50% deeper than the depth of 95W rods with same dimension size. © 2012 Elsevier Ltd.


Zhou Q.,University of Portsmouth | Zhou Q.,Nanjing University of Science and Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | And 2 more authors.
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2012

This paper focuses on the problem of neural-network-based decentralized adaptive output-feedback control for a class of nonlinear strict-feedback large-scale stochastic systems. The dynamic surface control technique is used to avoid the explosion of computational complexity in the backstepping design process. A novel direct adaptive neural network approximation method is proposed to approximate the unknown and desired control input signals instead of the unknown nonlinear functions. It is shown that the designed controller can guarantee all the signals in the closed-loop system to be semiglobally uniformly ultimately bounded in a mean square. Simulation results are provided to demonstrate the effectiveness of the developed control design approach. © 1996-2012 IEEE.


Liu M.,Qingdao University of Science and Technology | Zhang J.,Qingdao University of Science and Technology | Liu J.,Nanjing University of Science and Technology | Yu W.W.,Jilin University
Journal of Catalysis | Year: 2011

Stable poly(N-vinyl-2-pyrrolidone)-stabilized Pt/Ru colloidal nanoparticles (PVP-Pt/Ru) were prepared via ethanol reduction of H2PtCl 66H2O and RuCl3nH2O. The average diameters of the nanoparticles with different molar ratio of Pt/Ru were in a range of 2.1-2.8 nm with narrow size distributions. X-ray photoelectron spectroscopy verified that both Pt and Ru were in the metallic state and Ru was rich on the surface. These nanoparticles were employed to selectively hydrogenate ortho-chloronitrobenzene at 298 K and 0.1 MPa hydrogen pressure. They showed high activity [TOF was in the range of 0.8-5.3 × 10 -2 molo-CNB/(molM,surface atom) s] and high selectivity (93-99%) to ortho-chloroaniline (o-CAN) for the reaction, which were composition-dependent. The selectivity to o-CAN monotonously increased, but the activity of the catalyst decreased with the increasing proportion of Ru in Pt/Ru colloidal catalysts. PVP-1Pt/4Ru nanoparticles exhibited the highest selectivity of 99.0% to o-CAN at a complete conversion. © 2010 Elsevier Inc. All rights reserved.


Zhou Q.,Nanjing University of Science and Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne
International Journal of Robust and Nonlinear Control | Year: 2012

This paper deals with the problem of network-based H ∞ control for a class of uncertain stochastic systems with both network-induced delays and packet dropouts. The networked control system under consideration is represented by a stochastic model, which consists of two successive delay components in the state. The uncertainties are assumed to be time varying and norm bounded. Sufficient conditions for the existence of H ∞ controller are proposed to ensure exponentially stable in mean square of the closed-loop system that also satisfies a prescribed performance. The conditions are expressed in the frame of linear matrix inequalities (LMIs), which can be verified easily by means of standard software. Two practical examples are provided to show the effectiveness of the proposed techniques. Copyright © 2011 John Wiley & Sons, Ltd.


Zhang P.,Nanjing University of Science and Technology | Zhang P.,Guilin University of Electronic Technology | Li Q.,Nanjing University of Science and Technology | Xuan Y.,Nanjing University of Science and Technology
Composites Part A: Applied Science and Manufacturing | Year: 2014

To enhance heat transfer performance of epoxy resin as a thermal interface material (TIM), multi-walled carbon nanotubes (MWCNTs) and nano-copper particles are incorporated into an epoxy resin to form hybrid composites. The total thermal contact resistance (TCR) between the heated and cooled surfaces as well as its components such as the bulk resistance (RBLT) of the TIM, and the boundary resistance (RB) between the TIM and the joint surfaces above and below the TIM of the composites are measured. The influence of the compound in different proportions of MWCNTs and nano-copper particles on R BLT and RB is discussed in detail. The results indicate that the total TCR is related not only to the thermal conductivity of the TIM, but also to the other factors such as the property of the filler, the microstructural characterization, and the surface morphology of the TIM.© 2013 Elsevier Ltd. All rights reserved.


Greenbaum A.,University of California at Los Angeles | Luo W.,University of California at Los Angeles | Su T.-W.,University of California at Los Angeles | Gorocs Z.,University of California at Los Angeles | And 6 more authors.
Nature Methods | Year: 2012

We discuss unique features of lens-free computational imaging tools and report some of their emerging results for wide-field on-chip microscopy, such as the achievement of a numerical aperture (NA) of ∼0.8-0.9 across a field of view (FOV) of more than 20 mm2 or an NA of ∼0.1 across a FOV of ∼18 cm2, which corresponds to an image with more than 1.5 gigapixels. We also discuss the current challenges that these computational on-chip microscopes face, shedding light on their future directions and applications. © 2012 Nature America, Inc. All rights reserved.


Che Y.,Nanjing University of Science and Technology | Benson B.L.,Florida State University
Journal of Drug Issues | Year: 2014

Decision making in the face of risk from law enforcement is considered from the perspective provided by theoretical models of interdependent decisions of potential drug smugglers regarding entry and the use of violence following entry. Implications of three different models of decision making under risk are examined: expected value, expected utility, and prospect theory. The theoretical results help explain many observed characteristics of drug-smuggling operations and allow clarification of some implications drawn from studies of smuggling behavior that were not considered in the context of such models. © The Author(s) 2013.


Li Z.,Nanjing University of Science and Technology | Liu J.,CAS Institute of Automation | Yang Y.,Queensland University of Technology | Zhou X.,CAS Institute of Automation | Lu H.,CAS Institute of Automation
IEEE Transactions on Knowledge and Data Engineering | Year: 2014

Many pattern analysis and data mining problems have witnessed high-dimensional data represented by a large number of features, which are often redundant and noisy. Feature selection is one main technique for dimensionality reduction that involves identifying a subset of the most useful features. In this paper, a novel unsupervised feature selection algorithm, named clustering-guided sparse structural learning (CGSSL), is proposed by integrating cluster analysis and sparse structural analysis into a joint framework and experimentally evaluated. Nonnegative spectral clustering is developed to learn more accurate cluster labels of the input samples, which guide feature selection simultaneously. Meanwhile, the cluster labels are also predicted by exploiting the hidden structure shared by different features, which can uncover feature correlations to make the results more reliable. Row-wise sparse models are leveraged to make the proposed model suitable for feature selection. To optimize the proposed formulation, we propose an efficient iterative algorithm. Finally, extensive experiments are conducted on 12 diverse benchmarks, including face data, handwritten digit data, document data, and biomedical data. The encouraging experimental results in comparison with several representative algorithms and the theoretical analysis demonstrate the efficiency and effectiveness of the proposed algorithm for feature selection. © 1989-2012 IEEE.


Zhang L.,Nanjing University of Science and Technology | Sun K.,Tsinghua University | Xing Y.,Nanjing University of Science and Technology | Feng L.,Nanjing University of Science and Technology | Ge H.,Nanjing University of Science and Technology
IEEE Transactions on Power Electronics | Year: 2011

In order to enhance the efficiency and reliability for distributed microgeneration, a modular grid-connected photovoltaic (PV) generation system is proposed. It consists of modular dc-dc converters and modular dc-ac inverters. The outputs of dcdc converter and the inputs of dc-ac inverter share a dc bus. AC current coupling between the parallel-operated inverters, which is the key issue in this generation system, has been investigated. A current-decoupling method is proposed and implemented by regulating the currents of split-filter inductors, respectively. An optimal control strategy for the efficiency enhancement of PV generation system is proposed by utilizing the dispersion of control parameters. During power generation, only one modular dc-ac inverter is operating with nonfull load, and the other modular dc-ac inverters are operating with full load or at standby mode. A prototype of this modularized grid-connected PV generation system is implemented. The steady state and dynamic experimental results show that the fundamental components of two split-filter inductor currents in one inverter module are equivalent, which are decoupled completely, and only one inverter module operates with nonfull load among the parallel-operated inverter modules. The feasibility of the proposed system and the effectiveness of the control strategies have been verified by experimental results. © 2006 IEEE.


Zhou Q.,Nanjing University of Science and Technology | Zhou Q.,Victoria University of Melbourne | Shi P.,Victoria University of Melbourne | Shi P.,University of South Wales | And 2 more authors.
IEEE Transactions on Fuzzy Systems | Year: 2011

This paper is concerned with the problem of adaptive fuzzy tracking control via output feedback for a class of uncertain single-input single-output (SISO) strict-feedback nonlinear systems. The dynamic feedback strategy begins with an input-driven filter. By utilizing fuzzy logic systems to approximate unknown and desired control input signals directly instead of the unknown nonlinear functions, an output-feedback fuzzy tracking controller is designed via a backstepping approach. It is shown that the proposed fuzzy adaptive output controller can guarantee that all the signals remain bounded and that the tracking error converges to a small neighborhood of the origin. Simulations results are presented to demonstrate the effectiveness of the proposed methods. © 2011 IEEE.


Ren Y.-M.,Anhui Polytechnic University | Cai C.,Nanjing University of Science and Technology | Yang R.-C.,Anhui Polytechnic University
RSC Advances | Year: 2013

The multicomponent reactions (MCRs) consist of two or more synthetic steps which are carried out without isolation of any intermediate thus reducing time, saving money, energy and raw materials. The development of MCRs in the presence of molecular iodine is an efficient approach that meets with the requirements of sustainable chemistry. The aim of this review is to highlight the synergistic effect of the combined use of MCRs and molecular iodine for the development of new eco-compatible methodologies for organic chemistry. © The Royal Society of Chemistry 2013.


Fang T.H.,CAS Shenyang Institute of Metal Research | Tao N.R.,CAS Shenyang Institute of Metal Research | Lu K.,CAS Shenyang Institute of Metal Research | Lu K.,Nanjing University of Science and Technology
Scripta Materialia | Year: 2014

With surface mechanical grinding treatment, a gradient nanograined (GNG) surface layer is produced on a bulk coarse-grained (CG) pure Cu, where the grain size increases gradually from 20 nm (topmost surface) to micrometer scale. Microhardness measurements of the GNG/CG sample after tension revealed that tension induces softening for grains smaller than 165 nm and induces hardening above this size. This critical size agrees with the strain-induced saturation grain size of Cu subjected to severe plastic deformation. © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Cao J.,Nanjing University of Finance and Economics | Wu Z.,Nanjing University of Finance and Economics | Wang Y.,Nanjing University of Science and Technology | Zhuang Y.,Zhejiang GongShang University
Knowledge and Information Systems | Year: 2013

Web service recommendation has become a hot yet fundamental research topic in service computing. The most popular technique is the Collaborative Filtering (CF) based on a user-item matrix. However, it cannot well capture the relationship between Web services and providers. To address this issue, we first design a cube model to explicitly describe the relationship among providers, consumers and Web services. And then, we present a Standard Deviation based Hybrid Collaborative Filtering (SD-HCF) for Web Service Recommendation (WSRec) and an Inverse consumer Frequency based User Collaborative Filtering (IF-UCF) for Potential Consumers Recommendation (PCRec). Finally, the decision-making process of bidirectional recommendation is provided for both providers and consumers. Sets of experiments are conducted on real-world data provided by Planet-Lab. In the experiment phase, we show how the parameters of SD-HCF impact on the prediction quality as well as demonstrate that the SD-HCF is much better than extant methods on recommendation quality, including the CF based on user, the CF based on item and general HCF. Experimental comparison between IF-UCF and UCF indicates the effectiveness of adding inverse consumer frequency to UCF. © 2012 Springer-Verlag London.


Xu D.,Nanjing University of Science and Technology | Ugrinovskii V.,Tech Force
Systems and Control Letters | Year: 2013

This paper studies the problem of decentralized measurement feedback stabilization of nonlinear interconnected systems. As a natural extension of the recent development on control vector Lyapunov functions, the notion of output control vector Lyapunov function (OCVLF) is introduced for investigating decentralized measurement feedback stabilization problems. Sufficient conditions on (local) stabilizability are discussed which are based on the proposed notion of OCVLF. It is shown that a decentralized controller for a nonlinear interconnected system can be constructed using these conditions under an additional vector dissipation-like condition. To illustrate the proposed method, two examples are given. © 2013 Elsevier B.V. All rights reserved.


Zhang J.-K.,McMaster University | Huang F.,Nanjing University of Science and Technology | Ma S.,University of Jinan
IEEE Transactions on Information Theory | Year: 2011

In this paper, the systematic design of a space-time block code is considered for a wireless communication system with multiple transmitter-receiver antennas and flat fading, in which channel state information is completely unknown. From the viewpoint of blind signal processing, a necessary and sufficient condition is given for the unique identification of the multi-input multi-output flat fading channel and transmitted signal. Then, some novel unique factorizations for a pair of coprime P-ary and Q-ary phase shift keying (PSK) constellations are established. With this and currently available coherent space-time block code designs, a method is developed to systematically construct full diversity blind nonunitary space-time block codes as well as unitary codes by just performing the QR decomposition of the nonunitary codes. It is proved that under a noise-free environment, the code design proposed in this paper can guarantee that the transmitted signals and the channel coefficients are uniquely identified, and that under a complex Gaussian noise environment in which Pth-order and Q th-order statistics (P and Q are co-prime) of the received signals are available, the channel coefficients can be still uniquely identified. In addition, a closed-form solution to determine the channel coefficients is obtained. © 2011 IEEE.


Li H.,Harbin Institute of Technology | Li H.,University of Portsmouth | Zhou Q.,Nanjing University of Science and Technology | Chen B.,Qingdao University | Liu H.,University of Portsmouth
Journal of the Franklin Institute | Year: 2011

In this paper, the problem of parameter-dependent robust stability analysis is addressed for uncertain Markovian jump linear systems (MJLSs) with polytopic parameter uncertainties and time-varying delay. By constructing parameter-dependent Lyapunov functional, some sufficient conditions are developed to enable robust exponential mean square stability for the systems. New parameter-dependent robust stability criteria for MJLSs are established in the form of linear matrix inequalities (LMIs), which can be solved efficiently by the interior-point algorithm. Finally, a numerical example is given to demonstrate the effectiveness of the proposed approach. © 2011 The Franklin Institute © 2011 Published by Elsevier Ltd. on behalf of The Franklin Institute.


Mao J.-R.,Nanjing University of Science and Technology | Mao J.-R.,Aviation Industry Corporation of China | Choi W.-W.,Macau University of Science and Technology | Tam K.-W.,Macau University of Science and Technology | And 2 more authors.
IEEE Transactions on Microwave Theory and Techniques | Year: 2013

In this paper, a tunable bandpass filter using crossshaped multiple mode resonators (MMRs) and transformer based external quality factor tuning structures is proposed. The use of a cross-shaped MMR simplifies inter-resonators control while two tuning structures are investigated and incorporated with theMMR to implement simultaneous center frequency agility and narrow and wide bandwidth tuning. Compared with traditional tunable filters, the proposed architecture requires less tuning elements and is easier to realize wideband and high-order tunable filters. Two examples (Filter I and II) are presented to validate the design. Both filters use a single MMR and six tuning elements to achieve a third-order wideband tunable filter. Filter I reports 58% center frequency tuning with constant bandwidth and 14%-64.4% fractional bandwidth (FBW) tuning when center frequency locates at 1 GHz. Filter II achieves larger frequency agility and wider FBW tuning of 82.9% and 95%, respectively, for the same bandwidth and center frequency of Filter I. © 2013 IEEE.


Zhao Y.,City College of New York | Zhao Y.,Nanjing University of Science and Technology | Seredych M.,City College of New York | Zhong Q.,Nanjing University of Science and Technology | Bandosz T.J.,City College of New York
ACS Applied Materials and Interfaces | Year: 2013

New composites Cu-BTC MOF and graphite oxide modified with urea (GO-U) are developed and tested as CO2 adsorbents at room temperature. The composite containing GO-U with the highest nitrogen content exhibits an excellent CO2 uptake (4.23 mmol/g) at dynamic conditions. The incorporation of GO-U into MOF changes the chemistry and microstructure of the parent MOF and results in synergistic features beneficial for CO2 retention on the surface. To identify these features the initial and exhausted materials were extensively characterized from the points of view of their porosity and chemistry. Although the adsorption forces are relatively strong, the results indicate that CO2 is mainly physisorbed on the composites at dry dynamic conditions at ambient temperature and pressure. The primary adsorption sites include small micropores specific for the composites, open Cu sites, and cage window sites. © 2013 American Chemical Society.


Lu G.-F.,Nanjing University of Science and Technology | Lu G.-F.,Anhui Science and Technology University | Lin Z.,Nanjing University of Science and Technology | Jin Z.,Nanjing University of Science and Technology
Pattern Recognition | Year: 2010

In this paper, we propose a new discriminant locality preserving projections based on maximum margin criterion (DLPP/MMC). DLPP/MMC seeks to maximize the difference, rather than the ratio, between the locality preserving between-class scatter and locality preserving within-class scatter. DLPP/MMC is theoretically elegant and can derive its discriminant vectors from both the range of the locality preserving between-class scatter and the range space of locality preserving within-class scatter. DLPP/MMC can also derive its discriminant vectors from the null space of locality preserving within-class scatter when the parameter of DLPP/MMC approaches +∞. Experiments on the ORL, Yale, FERET, and PIE face databases show the effectiveness of the proposed DLPP/MMC. © 2010 Elsevier Ltd. All rights reserved.


Xu X.,Nanjing University of Science and Technology | Wang J.,Nanjing University of Science and Technology | Zhu L.,Macau University of Science and Technology
IEEE Microwave and Wireless Components Letters | Year: 2013

A new approach to design differential-mode (DM) bandpass filters is proposed and implemented based on the substrate integrated waveguide (SIW) technology. By properly constructing the topologies of SIW resonant cavities, the balanced section of the proposed filter achieves an attractive capacity in simultaneously realizing the desired DM transmission and expected common-mode (CM) suppression in a certain band. In design, the specified DM frequency response is achieved with an equivalent two-port circuit model. To illustrate the possibilities of the new approach, a fourth-order Ku-band prototype is designed and fabricated on a single-layer substrate. Measured results agree well with the predicted counterparts. © 2013 IEEE.


Qiu J.,Harbin Institute of Technology | Feng G.,City University of Hong Kong | Feng G.,Nanjing University of Science and Technology | Gao H.,Harbin Institute of Technology
IEEE Transactions on Fuzzy Systems | Year: 2012

This paper is concerned with the problem of robust ${\mathscr H}infty output feedback control for a class of continuous-time Takagi-Sugeno (T-S) fuzzy affine dynamic systems using quantized measurements. The objective is to design a suitable observer-based dynamic output feedback controller that guarantees the global stability of the resulting closed-loop fuzzy system with a prescribed ${\mathscr H}\infty disturbance attenuation level. Based on common/piecewise quadratic Lyapunov functions combined with S-procedure and some matrix inequality convexification techniques, some new results are developed to the controller synthesis for the underlying continuous-time T-S fuzzy affine systems with unmeasurable premise variables. All the solutions to the problem are formulated in the form of linear matrix inequalities (LMIs). Finally, two simulation examples are provided to illustrate the advantages of the proposed approaches. © 1993-2012 IEEE.


Xu Y.,Harbin Institute of Technology | Zhang D.,Harbin Institute of Technology | Zhang D.,Hong Kong Polytechnic University | Yang J.-Y.,Nanjing University of Science and Technology
Pattern Recognition | Year: 2010

Bimodal biometrics has been found to outperform single biometrics and are usually implemented using the matching score level or decision level fusion, though this fusion will enable less information of bimodal biometric traits to be exploited for personal authentication than fusion at the feature level. This paper proposes matrix-based complex PCA (MCPCA), a feature level fusion method for bimodal biometrics that uses a complex matrix to denote two biometric traits from one subject. The method respectively takes the two images from two biometric traits of a subject as the real part and imaginary part of a complex matrix. MCPCA applies a novel and mathematically tractable algorithm for extracting features directly from complex matrices. We also show that MCPCA has a sound theoretical foundation and the previous matrix-based PCA technique, two-dimensional PCA (2DPCA), is only one special form of the proposed method. On the other hand, the features extracted by the developed method may have a large number of data items (each real number in the obtained features is called one data item). In order to obtain features with a small number of data items, we have devised a two-step feature extraction scheme. Our experiments show that the proposed two-step feature extraction scheme can achieve a higher classification accuracy than the 2DPCA and PCA techniques. © 2009 Elsevier Ltd. All rights reserved.


Xu Y.,Harbin Institute of Technology | Zhong A.,Harbin Institute of Technology | Yang J.,Nanjing University of Science and Technology | Zhang D.,Hong Kong Polytechnic University
Pattern Recognition | Year: 2010

Locality preserving projection (LPP) is a manifold learning method widely used in pattern recognition and computer vision. The face recognition application of LPP is known to suffer from a number of problems including the small sample size (SSS) problem, the fact that it might produce statistically identical transform results for neighboring samples, and that its classification performance seems to be heavily influenced by its parameters. In this paper, we propose three novel solution schemes for LPP. Experimental results also show that the proposed LPP solution scheme is able to classify much more accurately than conventional LPP and to obtain a classification performance that is only little influenced by the definition of neighbor samples. © 2010 Elsevier Ltd. ALL rights reserved.


Yong X.,Harbin Institute of Technology | Zhang D.,Hong Kong Polytechnic University | Yang J.,Nanjing University of Science and Technology | Zhong J.,Nanjing University of Science and Technology
International Journal of Information Technology and Decision Making | Year: 2011

Since in the feature space the eigenvector is a linear combination of all the samples from the training sample set, the computational efficiency of KPCA-based feature extraction falls as the training sample set grows. In this paper, we propose a novel KPCA-based feature extraction method that assumes that an eigenvector can be expressed approximately as a linear combination of a subset of the training sample set ("nodes"). The new method selects maximally dissimilar samples as nodes. This allows the eigenvector to contain the maximum amount of information of the training sample set. By using the distance metric of training samples in the feature space to evaluate their dissimilarity, we devised a very simple and quite efficient algorithm to identify the nodes and to produce the sparse KPCA. The experimental result shows that the proposed method also obtains a high classification accuracy. © 2011 World Scientific Publishing Company.


Pu C.,Nanjing University of Science and Technology | Li S.,Nanjing University of Science and Technology | Michaelson A.,State University of New York at Stony Brook | Yang J.,Nanjing University of Science and Technology
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2015

We investigate a path-attack process on model networks and real-world networks. Based on the local topological structure of a path, we propose an attack centrality measure with a control parameter α for quantifying the influence of a path. In the path-attack process, we iteratively remove the path with the largest attack centrality from a network. Results demonstrate that, for a specific network, there is an optimal α which results in maximum attack efficiency. The denser and more homogeneous the networks, the more robust the networks are against iterative path attacks. Our work helps to explain the vulnerability of networks and provides some clues about the protection and design of real complex systems. © 2015 Elsevier B.V. All rights reserved.


Zhang C.,City University of Hong Kong | Feng G.,City University of Hong Kong | Feng G.,Nanjing University of Science and Technology | Qiu J.,City University of Hong Kong | And 2 more authors.
IEEE Transactions on Industrial Electronics | Year: 2013

This paper investigates the controller design for a class of linear network-based systems with communication constraints on both uplink and downlink channels, where the network-induced transmission time delay, packet dropouts, and signal quantization are considered simultaneously. To deal with the phenomenon of quantization, a novel approach is adopted, which converts the quantized state and control signal into a kind of actuator saturation with bounded disturbances. Based on a proposed Lyapunov-Krasovskii functional, the existence conditions of a linear memory-less state feedback controller are derived, and an estimation method for the domain of admissible initial conditions is proposed from which all solutions of the systems under study converge exponentially to an ellipsoid with a prescribed convergence rate. Finally, a simulation example is provided to show the effectiveness of the developed approach. © 1982-2012 IEEE.


Song J.,Nanjing University of Science and Technology | Song J.,Nanjing University of Aeronautics and Astronautics | Kulinich S.A.,Tokai University | Kulinich S.A.,Aston University | And 4 more authors.
Angewandte Chemie - International Edition | Year: 2015

For all-solution-processed (ASP) devices, transparent conducting oxide (TCO) nanocrystal (NC) inks are anticipated as the next-generation electrodes to replace both those synthesized by sputtering techniques and those consisting of rare metals, but a universal and one-pot method to prepare these inks is still lacking. A universal one-pot strategy is now described; through simply heating a mixture of metal-organic precursors a wide range of TCO NC inks, which can be assembled into high-performance electrodes for use in ASP optoelectronics, were synthesized. This method can be used for various oxide NC inks with yields as high as 10 g. The formed NCs are of high crystallinity, uniform morphology, monodispersity, and high ink stability and feature effective doping. Therefore, the inks can be readily assembled into films with a surface roughness of 1.6 nm. Typically, a sheet resistance of 110 Ω sq-1 can be achieved with a transmittance of 88%, which is the best performance for TCO NC ink-based electrodes described to date. These electrodes can thus drive a polymer light-emitting diode (PLED) with a luminance of 2200 cdm-2 at 100 mA cm-2. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA.


Liu Y.,CAS Institute of Automation | Liu J.,CAS Institute of Automation | Li Z.,CAS Institute of Automation | Tang J.,Nanjing University of Science and Technology | Lu H.,CAS Institute of Automation
Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition | Year: 2013

In this paper, we propose a novel Weakly-Supervised Dual Clustering (WSDC) approach for image semantic segmentation with image-level labels, i.e., collaboratively performing image segmentation and tag alignment with those regions. The proposed approach is motivated from the observation that super pixels belonging to an object class usually exist across multiple images and hence can be gathered via the idea of clustering. In WSDC, spectral clustering is adopted to cluster the super pixels obtained from a set of over-segmented images. At the same time, a linear transformation between features and labels as a kind of discriminative clustering is learned to select the discriminative features among different classes. The both clustering outputs should be consistent as much as possible. Besides, weakly-supervised constraints from image-level labels are imposed to restrict the labeling of super pixels. Finally, the non-convex and non-smooth objective function are efficiently optimized using an iterative CCCP procedure. Extensive experiments conducted on MSRC and Label Me datasets demonstrate the encouraging performance of our method in comparison with some state-of-the-arts. © 2013 IEEE.


Gao Q.,Hefei University of Technology | Gao Q.,City University of Hong Kong | Feng G.,City University of Hong Kong | Feng G.,Nanjing University of Science and Technology | And 2 more authors.
IEEE Transactions on Fuzzy Systems | Year: 2013

This paper investigates the universal fuzzy model and universal fuzzy controller problems for stochastic nonaffine nonlinear systems. The underlying mechanism of stochastic fuzzy logic is first discussed, and a stochastic generalized fuzzy model with new stochastic fuzzy rule base is then given. Based on their function approximation capability, these kinds of stochastic generalized fuzzy models are shown to be universal fuzzy models for stochastic nonaffine nonlinear systems under some sufficient conditions. An approach to stabilization controller design for stochastic nonaffine nonlinear systems is then developed through their stochastic generalized Takagi-Sugeno (T-S) fuzzy approximation models. Then, the results of universal fuzzy controllers for two classes of stochastic nonlinear systems, along with constructive procedures to obtain the universal fuzzy controllers, are also provided, respectively. Finally, a numerical example is presented to illustrate the effectiveness of the proposed approach. © 1993-2012 IEEE.


Qiu J.,Harbin Institute of Technology | Feng G.,City University of Hong Kong | Feng G.,Nanjing University of Science and Technology | Gao H.,Harbin Institute of Technology
IEEE Transactions on Fuzzy Systems | Year: 2013

This paper investigates the problem of robust H∞ output feedback control for a class of continuous-time Takagi-Sugeno (T-S) fuzzy affine dynamic systems with parametric uncertainties and input constraints. The objective is to design a suitable constrained piecewise affine static output feedback controller, guaranteeing the asymptotic stability of the resulting closed-loop fuzzy control system with a prescribed H∞ disturbance attenuation level. Based on a smooth piecewise quadratic Lyapunov function combined with S-procedure and some matrix inequality convexification techniques, some new results are developed for static output feedback controller synthesis of the underlying continuous-time T-S fuzzy affine systems. It is shown that the controller gains can be obtained by solving a set of linear matrix inequalities (LMIs). Finally, three examples are provided to illustrate the effectiveness of the proposed methods. © 1993-2012 IEEE.


Qiu J.,Harbin Institute of Technology | Feng G.,City University of Hong Kong | Feng G.,Nanjing University of Science and Technology | Gao H.,Harbin Institute of Technology
IEEE Transactions on Fuzzy Systems | Year: 2011

This paper investigates the problem of robust ℋ∞ output-feedback control for a class of networked nonlinear systems with multiple packet dropouts. The nonlinear plant is represented by Takagi-Sugeno (T-S) fuzzy affine dynamic models with norm-bounded uncertainties, and stochastic variables that satisfy the Bernoulli random binary distribution are adopted to characterize the data-missing phenomenon. The objective is to design an admissible output-feedback controller that guarantees the stochastic stability of the resulting closed-loop system with a prescribed ℋ∞ disturbance attenuation level. It is assumed that the plant premise variables, which are often the state variables or their functions, are not measurable so that the controller implementation with state-space partition may not be synchronous with the state trajectories of the plant. Based on a piecewise quadratic Lyapunov function combined with an S-procedure and some matrix inequality convexifying techniques, two different approaches to robust output-feedback controller design are developed for the underlying T-S fuzzy affine systems with unreliable communication links. The solutions to the problem are formulated in the form of linear matrix inequalities (LMIs). Finally, simulation examples are provided to illustrate the effectiveness of the proposed approaches. © 2011 IEEE.


Zhang C.,City University of Hong Kong | Feng G.,City University of Hong Kong | Feng G.,Nanjing University of Science and Technology | Gao H.,Harbin Institute of Technology | And 2 more authors.
IEEE Transactions on Fuzzy Systems | Year: 2011

This paper investigates the problem of H∞ filtering for a class of nonlinear discrete-time systems with measurement quantization and packet dropouts. Each output is transmitted via an independent communication channel, and the phenomenon of packet dropouts in transmission is governed by an individual random binary distribution, while the quantization errors are treated as sector-bound uncertainties. Based on a piecewise-Lyapunov function, an approach to the design of H∞-piecewise filter is proposed such that the filtering-error system is stochastically stable with a guaranteed H∞ performance. Some slack matrices are introduced to facilitate the filter design procedure by eliminating the coupling between the Lyapunov matrices and the system matrices. The filter parameters can be obtained by solving a set of linear-matrix inequalities (LMIs), which are numerically tractable with commercially available software. Finally, two illustrative examples are provided to show the effectiveness of the proposed method. © 2011 IEEE.


Qiu J.,Harbin Institute of Technology | Qiu J.,City University of Hong Kong | Feng G.,City University of Hong Kong | Feng G.,Nanjing University of Science and Technology | Gao H.,Harbin Institute of Technology
IEEE Transactions on Fuzzy Systems | Year: 2011

This paper investigates the problem of robust ℋ∞state estimation for a class of multichannel networked nonlinear systems with multiple packet dropouts. The nonlinear plant is represented by TakagiSugeno (TS) fuzzy-affine dynamic models with norm-bounded uncertainties, and stochastic variables with general probability distributions are adopted to characterize the data missing phenomenon in output channels. The objective is to design an admissible state estimator guaranteeing the stochastic stability of the resulting estimation-error system with a prescribed ℋ ∞disturbance attenuation level. It is assumed that the plant premise variables, which are often the state variables or their functions, are not measurable so that the estimator implementation with state-space partition may not be synchronized with the state trajectories of the plant. Based on a piecewise-quadratic Lyapunov function combined with S -procedure and some matrix-inequality-convexifying techniques, two different approaches are developed to robust filtering design for the underlying TS fuzzy-affine systems with unreliable communication links. All the solutions to the problem are formulated in the form of linear-matrix inequalities (LMIs). Finally, simulation examples are provided to illustrate the effectiveness of the proposed approaches. © 2006 IEEE.


Wang J.,Nanjing University of Science and Technology | Song Y.,Nanjing University of Science and Technology | Li Z.-H.,Nanjing University of Science and Technology | Kempf A.,University of Duisburg - Essen | He A.-Z.,Nanjing University of Science and Technology
Optics Letters | Year: 2015

Flame chemiluminescence tomography (FCT) has been widely used in flame diagnostics for three-dimensional (3D), spatially resolved measurements of instantaneous flame geometry and, to some extent, of species concentrations. However, in most studies, tomographic reconstructions are based on a traditional parallel projection model. Due to the light collection characteristics of a lens, a parallel projection model is not appropriate for the practical optical setups that are used for emission imaging, particularly at small F-numbers. Taking the light collection effect of the lens into account, this Letter establishes a complete and novel tomographic theory for a multi-directional tomography system consisting of a lens and CCD cameras. A modified camera calibration method is presented first. It determines the exact spatial locations and intrinsic parameters of the cameras. A 3D projection model based on the lens imaging theory is then proposed and integrated into the multiplicative algebraic reconstruction technique (MART). The new approach is demonstrated with a 12-camera system that is used to reconstruct the emission field of a propane flame, thereby resolving space and time. © 2015 Optical Society of America.


Yang J.,Nanjing University of Science and Technology | Yang J.,California Institute of Technology | Zhang L.,Hong Kong Polytechnic University | Xu Y.,Harbin Institute of Technology | Yang J.-Y.,Nanjing University of Science and Technology
Pattern Recognition | Year: 2012

The newly-emerging sparse representation-based classifier (SRC) shows great potential for pattern classification but lacks theoretical justification. This paper gives an insight into SRC and seeks reasonable supports for its effectiveness. SRC uses L1-optimizer instead of L0- optimizer on account of computational convenience and efficiency. We re-examine the role of L1-optimizer and find that for pattern recognition tasks, L1-optimizer provides more classification meaningful information than L0-optimizer does. L0-optimizer can achieve sparsity only, whereas L1-optimizer can achieve closeness as well as sparsity. Sparsity determines a small number of nonzero representation coefficients, while closeness makes the nonzero representation coefficients concentrate on the training samples with the same class label as the given test sample. Thus, it is closeness that guarantees the effectiveness of the L1-optimizer based SRC. Based on the closeness prior, we further propose two kinds of class L1-optimizer classifiers (CL1C), the closeness rule based CL1C (C-CL1C) and its improved version: the Lasso rule based CL1C (L-CL1C). The proposed classifiers are evaluated on five databases and the experimental results demonstrate advantages of the proposed classifiers over SRC in classification performance and computational efficiency for large sample size problems. © 2011 Elsevier Ltd. All rights reserved.


Song C.-J.,Nanjing University of Science and Technology | Zhang Y.,Suzhou University of Science and Technology
International Journal of Theoretical Physics | Year: 2015

Based on El-Nabulsi-Birkhoff fractional equations, Lie symmetry and the Hojman conserved quantity, the Noether conserved quantity deduced indirectly by the Lie symmetry and adiabatic invariants of Lie symmetrical perturbation are studied under the framework of El-Nabulsi’s fractional model. Firstly, Lie symmetry and the Hojman conserved quantity are obtained, including the equations of motion of EI-Nabulsi’s fractional Birkhoff system, the determining equations of Lie symmetry for the system and the generalization of the Hojman theorem. Secondly, the Noether conserved quantity deduced indirectly by the Lie symmetry is obtained. Thirdly, the adiabatic invariants of Lie symmetrical perturbation for disturbed EI-Nabulsi’s fractional Birkhoff system is achieved, including the disturbed El-Nabulsi-Birkhoff fractional equations, the determining equations of Lie symmetrical perturbation and adiabatic invariants for disturbed El-Nabulsi’s fractional Birkhoff system. Fourthly, adiabatic invariants and exact invariants under the special ifinitesimal transformations are presented. Finally, the Hojman-Urrutia problem is discussed to illustrate the application of these methods and results. © 2014, Springer Science+Business Media New York.


Shi S.,Nanjing University of Science and Technology | Choi W.-W.,Macau University of Science and Technology | Che W.,Nanjing University of Science and Technology | Tam K.-W.,Macau University of Science and Technology | Xue Q.,City University of Hong Kong
IEEE Microwave and Wireless Components Letters | Year: 2012

A novel microstrip ultra-wideband (UWB) differential filter with narrow notched band based on the transversal signal- interference concept is presented. In order to enhance the interference immunity from undesired signals efficiently, the notched band is implemented by coupling with quarter wavelength shorted-line at input and output ports. By taking advantage of the bandgap characteristic of defected ground structure (DGS), a slot-line DGS is used for improving the common-mode rejection. In this work, at the center frequency of the notched band which is 2.45 GHz, about 7.3% bandwidth (2.35-2.53 GHz) is realized by full-wave simulator. Agreement between experiment and simulation is observed. © 2012 IEEE.


Lai Z.,Harbin Institute of Technology | Xu Y.,Harbin Institute of Technology | Yang J.,Nanjing University of Science and Technology | Tang J.,Nanjing University of Science and Technology | Zhang D.,Hong Kong Polytechnic University
IEEE Transactions on Image Processing | Year: 2013

The classical linear discriminant analysis has undergone great development and has recently been extended to different cases. In this paper, a novel discriminant subspace learning method called sparse tensor discriminant analysis (STDA) is proposed, which further extends the recently presented multilinear discriminant analysis to a sparse case. Through introducing the L1 and L2 norms into the objective function of STDA, we can obtain multiple interrelated sparse discriminant subspaces for feature extraction. As there are no closed-form solutions, k-mode optimization technique and the L 1 norm sparse regression are combined to iteratively learn the optimal sparse discriminant subspace along different modes of the tensors. Moreover, each non-zero element in each subspace is selected from the most important variables/factors, and thus STDA has the potential to perform better than other discriminant subspace methods. Extensive experiments on face databases (Yale, FERET, and CMU PIE face databases) and the Weizmann action database show that the proposed STDA algorithm demonstrates the most competitive performance against the compared tensor-based methods, particularly in small sample sizes. © 1992-2012 IEEE.


Qian J.,Nanjing University of Science and Technology | Yang J.,Nanjing University of Science and Technology | Yang J.,California Institute of Technology | Xu Y.,Harbin Institute of Technology
IEEE Transactions on Image Processing | Year: 2013

This paper presents a robust but simple image feature extraction method, called image decomposition based on local structure (IDLS). It is assumed that in the local window of an image, the macro-pixel (patch) of the central pixel, and those of its neighbors, are locally linear. IDLS captures the local structural information by describing the relationship between the central macro-pixel and its neighbors. This relationship is represented with the linear representation coefficients determined using ridge regression. One image is actually decomposed into a series of sub-images (also called structure images) according to a local structure feature vector. All the structure images, after being down-sampled for dimensionality reduction, are concatenated into one super-vector. Fisher linear discriminant analysis is then used to provide a low-dimensional, compact, and discriminative representation for each super-vector. The proposed method is applied to face recognition and examined using our real-world face image database, NUST-RWFR, and five popular, publicly available, benchmark face image databases (AR, Extended Yale B, PIE, FERET, and LFW). Experimental results show the performance advantages of IDLS over state-of-the-art algorithms. © 2013 IEEE.


Xu Y.,Harbin Institute of Technology | Zhang D.,Hong Kong Polytechnic University | Yang J.,Nanjing University of Science and Technology | Yang J.-Y.,Nanjing University of Science and Technology
IEEE Transactions on Circuits and Systems for Video Technology | Year: 2011

In this paper, we propose a two-phase test sample representation method for face recognition. The first phase of the proposed method seeks to represent the test sample as a linear combination of all the training samples and exploits the representation ability of each training sample to determine M nearest neighbors for the test sample. The second phase represents the test sample as a linear combination of the determined M nearest neighbors and uses the representation result to perform classification. We propose this method with the following assumption: the test sample and its some neighbors are probably from the same class. Thus, we use the first phase to detect the training samples that are far from the test sample and assume that these samples have no effects on the ultimate classification decision. This is helpful to accurately classify the test sample. We will also show the probability explanation of the proposed method. A number of face recognition experiments show that our method performs very well. © 2011 IEEE.


Li Z.,Nanjing University of Science and Technology | Liu J.,CAS Institute of Automation | Tang J.,Nanjing University of Science and Technology | Lu H.,CAS Institute of Automation
IEEE Transactions on Pattern Analysis and Machine Intelligence | Year: 2015

To uncover an appropriate latent subspace for data representation, in this paper we propose a novel Robust Structured Subspace Learning (RSSL) algorithm by integrating image understanding and feature learning into a joint learning framework. The learned subspace is adopted as an intermediate space to reduce the semantic gap between the low-level visual features and the high-level semantics. To guarantee the subspace to be compact and discriminative, the intrinsic geometric structure of data, and the local and global structural consistencies over labels are exploited simultaneously in the proposed algorithm. Besides, we adopt the ℓ2,1 -norm for the formulations of loss function and regularization respectively to make our algorithm robust to the outliers and noise. An efficient algorithm is designed to solve the proposed optimization problem. It is noted that the proposed framework is a general one which can leverage several well-known algorithms as special cases and elucidate their intrinsic relationships. To validate the effectiveness of the proposed method, extensive experiments are conducted on diversity datasets for different image understanding tasks, i.e., image tagging, clustering, and classification, and the more encouraging results are achieved compared with some state-of-the-art approaches. © 1979-2012 IEEE.


Ren Y.-M.,Anhui Science and Technology University | Cai C.,Nanjing University of Science and Technology
Journal of Chemical Research | Year: 2010

An efficient method for the synthesis of 1,2,4,5-tetrasubstituted imidazoles by three-component condensation of benzil, benzonitrile derivatives and primary amines under solvent-free conditions using molecular iodine as catalyst is described with high product yields. The significant features of the iodine-catalysed condensation are operational simplicity, inexpensive reagents, high yield of products and use of non-toxic reagents.


Xu J.,Nanjing University of Science and Technology | Xu J.,Shaoguan University | Yang J.,Nanjing University of Science and Technology | Lai Z.,Harbin Institute of Technology
Information Sciences | Year: 2013

K-local hyperplane distance nearest neighbor (HKNN) classifier is an improved K-nearest neighbor (KNN) algorithm that has been successfully applied to pattern classification. This paper embeds the decision rule of HKNN classifier into the discriminant analysis model to develop a new feature extractor. The obtained feature extractor is called K-local hyperplane distance nearest neighbor classifier oriented local discriminant analysis (HOLDA), in which a regularization item is imposed on the original HKNN algorithm to obtain a more reliable distance metric. Based on this distance metric, the homo-class and hetero-class local scatters are characterized in HOLDA. By maximizing the ratio of the hetero-class local scatter to the homo-class local scatter, we obtain a subspace which is suitable for feature extraction and classification. In general, this paper provides a framework for building a feature extractor from the decision rule of a classifier. By this means, the feature extractor and classifier can be seamlessly integrated. Experimental results on four databases demonstrate that the integrated pattern recognition system is effective. © 2013 Elsevier Inc. All rights reserved.


Yuan Y.-H.,Jiangnan University | Sun Q.-S.,Nanjing University of Science and Technology
Pattern Recognition | Year: 2014

Multiset canonical correlation analysis (MCCA) is a powerful technique for analyzing linear correlations among multiple representation data. However, it usually fails to discover the intrinsic geometrical and discriminating structure of multiple data spaces in real-world applications. In this paper, we thus propose a novel algorithm, called graph regularized multiset canonical correlations (GrMCCs), which explicitly considers both discriminative and intrinsic geometrical structure in multiple representation data. GrMCC not only maximizes between-set cumulative correlations, but also minimizes local intraclass scatter and simultaneously maximizes local interclass separability by using the nearest neighbor graphs on within-set data. Thus, it can leverage the power of both MCCA and discriminative graph Laplacian regularization. Extensive experimental results on the AR, CMU PIE, Yale-B, AT&T, and ETH-80 datasets show that GrMCC has more discriminating power and can provide encouraging recognition results in contrast with the state-of-the-art algorithms. © 2014 Elsevier Ltd.


Zhao Y.,City College of New York | Zhao Y.,Nanjing University of Science and Technology | Seredych M.,City College of New York | Zhong Q.,Nanjing University of Science and Technology | Bandosz T.J.,City College of New York
RSC Advances | Year: 2013

New composites of a copper-based metal-organic framework and graphite oxide modified by urea (GO-U) were synthesized. The materials and the parent composite components were characterized using X-ray diffraction, FT-IR spectroscopy, potentiometric titration, sorption of nitrogen, thermal analysis, elemental analysis, Raman spectroscopy, UV-Vis spectroscopy, and scanning electron microscopy. The introduction of GO-U does not prevent the formation of MOF crystal structure. The synergistic effect of the composite formation is clearly seen in the surface features. The new materials exhibit a unique texture, high porosity and nitrogen enriched surface chemistry. Incorporation of amino groups in the specific chemical and structural environment enhances CO2 adsorption. Therefore, this kind of composites has a potential application in CO2 capture technologies to remit global warming. © 2013 The Royal Society of Chemistry.


Gao Q.,Hefei University of Technology | Gao Q.,City University of Hong Kong | Feng G.,City University of Hong Kong | Feng G.,Nanjing University of Science and Technology | And 2 more authors.
Fuzzy Sets and Systems | Year: 2012

This paper investigates the universal fuzzy control problem based on generalized T-S fuzzy models. The universal approximation capability of the generalized T-S fuzzy models is shown and an approach to robust controller design for general nonlinear systems based on this kind of generalized T-S fuzzy models is developed. The results of universal fuzzy controllers for two classes of nonlinear systems are then given, and constructive procedures to obtain the universal fuzzy controllers are also provided. An example is finally presented to show the effectiveness of our approach. © 2012 Elsevier B.V. All rights reserved.


Li J.,Zhejiang University of Technology | Chen Y.,Nanjing University of Science and Technology
Optics and Laser Technology | Year: 2012

Based on the theory of paraxial electromagnetic beams in anisotropic medium, propagation properties of a linearly polarized confluent hypergeometric (HyG) beam through uniaxial crystals orthogonal to the optical axis are investigated. Analytical expressions are derived for the resultant optical field components. Effects of separate beam parameters together with the ratio of refractive indices of crystals on transversal intensity distributions are revealed by numerical calculations, respectively. It is shown that the beam profile finally converts into an elliptical shape due to influences of anisotropic crystals. Moreover, it is also indicated that through suitable selection of parameters, types of the optical vortices of resultant field would change from a central dark spot to a slight dark ring or an axial shadow during the propagation. These numerical results may provide alternative advantages to the trapping of tiny particles by utilizing HyG beams in practical experiments. © 2011 Elsevier Ltd. All rights reserved.


Wang J.-T.,Huaibei Normal University | Chen D.-B.,Huaibei Normal University | Chen H.-Y.,Nanjing University of Science and Technology | Yang J.-Y.,Nanjing University of Science and Technology
Pattern Recognition Letters | Year: 2012

This article presents an approach for pedestrian detection and tracking from infrared imagery. The GMM background model is first deployed to separate the foreground candidates from background, then a shape describer is introduced to construct the feature vector for pedestrian candidates, and a SVM classifier is trained based on datasets generated from infrared images or manually. After detecting the pedestrian based on the SVM classifier, a multi-cues fusing algorithm is provided to facilitate the task of pedestrian tracking using both edge feature and intensity feature under the particle filter framework. Experimental results with various Infrared Video Database are reported to demonstrate the accuracy and robustness of our algorithm. © 2011 Elsevier B.V. All rights reserved.


Xiang Z.,Nanjing University of Science and Technology | Qiao C.,Nanjing University of Science and Technology | Mahmoud M.S.,King Fahd University of Petroleum and Minerals
Journal of the Franklin Institute | Year: 2012

This paper investigates the problem of robust H ∞ filtering for switched stochastic systems under asynchronous switching. The so-called asynchronous switching means that the switching between the filters and system modes is asynchronous. The aim is to design a filter ensuring robust exponential mean square stability and a prescribed H ∞ performance level for the filtering error systems. Based on the average dwell time approach and piecewise Lyapunov functional technique, sufficient conditions for the existence of the robust H ∞ filter are derived, and the proposed filter can be obtained by solving a set of LMIs(linear matrix inequalities). Finally, a numerical example is given to show the effectiveness of the proposed approach. © 2012 The Franklin Institute.


Li P.,University of Aizu | Guo S.,University of Aizu | Zhuang W.,University of Waterloo | Ye B.,Nanjing University of Science and Technology
IEEE Journal on Selected Areas in Communications | Year: 2014

Cooperative communication (CC) can offer high channel capacity and reliability in an efficient and low-cost way by forming a virtual antenna array among single-antenna nodes that cooperatively share their antennas. It has been well recognized that the selection of relay nodes plays a critical role in the performance of multiple source-destination pairs. Unfortunately, all prior work has made an unrealistic assumption that spectrum resources are unlimited and each source-destination pair can communicate over a dedicated channel with no mutual interference. In this paper, we study the problem of maximizing the minimum transmission rate among multiple source-destination pairs using CC in a cognitive radio network (CRN). We jointly consider the relay assignment and channel allocation under a finite set of available channels, where the interference must be considered. In order to improve the spectrum efficiency, we exploit the network coding opportunities existing in CC that can further increase the capacity. Such max-min rate problems for cognitive and cooperative communications are proved to be NP-hard and the corresponding MINLP (Mixed-Integer Nonlinear Programming) formulations are developed. Moreover, we apply the reformulation and linearization techniques to the original optimization problems with nonlinear and nonconvex objective functions such that our proposed algorithms can produce high competitive solutions in a timely manner. Extensive simulations are conducted to show that the proposed algorithms can achieve high spectrum efficiency in terms of providing a much improved max-min transmission rate under various network settings. © 1983-2012 IEEE.


Yan S.,University of Maryland University College | Yan S.,Nanjing University of Science and Technology | Jian G.,University of Maryland University College | Zachariah M.R.,University of Maryland University College
ACS Applied Materials and Interfaces | Year: 2012

In this work, we present a first time fabrication of thermite-based nanofiber mats with a nitrocellulose composite energetic binder to create a new class of energetic 1D nanocomposite. The as prepared thermite based nanofibrous mats were characterized and tested for their burning behavior, and compared with the pure nitrocellulose and nanoaluminum incorporated nanofibers for their combustion performances. Thermite-based nanofibers show enhanced burning rates in combustion tests, which correlate to the mass loading of nanothermite relative to binder in nanofibers. The electrospinning method demonstrates the possibility of avoiding some of the problems associated with melt casting nanometalized propellants. © 2012 American Chemical Society.


Xiang Z.,Nanjing University of Science and Technology | Qiao C.,Nanjing University of Science and Technology | Mahmoud M.S.,King Fahd University of Petroleum and Minerals
Journal of the Franklin Institute | Year: 2012

This paper is concerned with the finite-time stability, boundedness and H ∞ control problems for a class of switched stochastic systems. Using the average dwell time method and the multiple Lyapunov-like function technique, some sufficient conditions are proposed to guarantee the finite-time properties for the switched stochastic systems in the form of matrix inequalities. Also, a state feedback controller for the finite-time H ∞ control problem is obtained. An example is employed to verify the effectiveness of the proposed method. © 2011 The Franklin Institute.


Che W.,Nanjing University of Science and Technology | Gu L.,Nanjing University of Science and Technology | Chow Y.L.,University of Waterloo
IEEE Microwave and Wireless Components Letters | Year: 2010

Double-sided parallel strip line (DSPSL) is a versatile microwave transmission line. With an offset, it allows for large variations of the characteristic impedance and therefore flexibility for the design of novel microwave devices. In this letter, a formula for the characteristic impedance of DSPSL is derived by the fuzzy EM method and verified by commercial software. Very good agreement is observed. © 2010 IEEE.


Chen H.,Texas State University | Liu Y.,Nanjing University of Science and Technology
Robotics and Computer-Integrated Manufacturing | Year: 2013

Industrial robots used to perform assembly applications are still a small portion of total robot sales each year. One of the main reasons is that it is difficult for conventional industrial robots to adapt to any sort of change. This paper proposes a robust control strategy to perform an assembly task of inserting a printed circuit board (PCB) into an edge connector socket using a SCARA robot. The task is very challenging because it involves compliant manipulation in which a substantial force is needed to accomplish the insertion operation and there are some dynamic constraints from the environment. Therefore, a robust control algorithm is developed and used to perform the assembly process. The dynamic model of the robotic system is developed and the dynamic parameters are identified. Experiments were performed to validate the proposed method. Experimental results show that the robust control algorithm can deal with parameter uncertainties in the dynamic model, thus achieve better performance than the model based control method. An abnormal case is also investigated to demonstrate that the robust compliant control method can deal with the abnormal situation without damaging the system and assembly parts, while pure position control method may cause damages. This strategy can also be used in other similar assembly processes with compliant applications. © 2012 Elsevier Ltd. All rights reserved.


Yoshimura A.,University of Minnesota | Middleton K.R.,University of Minnesota | Zhu C.,Nanjing University of Science and Technology | Nemykin V.N.,University of Minnesota | Zhdankin V.V.,University of Minnesota
Angewandte Chemie - International Edition | Year: 2012

Look, no metal: A metal-free catalytic procedure for aziridination of alkenes using tetrabutylammonium iodide as the catalyst, m-chloroperoxybenzoic acid (mCPBA) as the terminal oxidant, and N-aminophthalimide as the nitrenium precursor has been developed (see scheme; right: X-ray structure of one of the products). Control experiments suggests that the active oxidant is in situ generated hypoiodous acid (HIO). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Ding J.,Nanjing University of Science and Technology | Zhong Q.,Nanjing University of Science and Technology | Zhang S.,Nanjing AIREP Environmental Protection Technology Co.
Fuel Processing Technology | Year: 2014

A novel oxidation-removal process for simultaneous removal of NO X and SO2 was developed, which utilized the catalytic ozonation over Ce-Ti catalyst and assisted with a glass made ammonia-based washing tower. Compared with conventional flue gas treatment, the present method acquires non-secondary pollution, minimal waste production and low operating costs. The main byproducts, ammonia sulfate and nitrate, are important fertilizers and industrially raw materials. A maximum removal of 95% for NO X and nearly complete SO2 removal were obtained with the assistance of washing tower under the following experimental conditions: O 3 concentration, 8.5 mg·L- 1; flow of oxidant mixtures, 100 mL·min- 1; simulated flue gas temperature, 120 °C; H2O flow, 2.4 mL·min- 1; and total gas flow, 400 mL·min- 1. The reaction mechanisms are discussed, and the final oxidation products are characterized. The experimental results show that the OH radicals from catalytic ozonation have an oxidation-removal effect of NOX and SO2. The multipollutant capacity of the washing tower is largely enhanced with the Ce-Ti catalyst. And the present method performs better stability with the assistance of the washing tower. © 2014 Published by Elsevier B.V.


He C.,East China Jiaotong University | He C.,Nanjing University of Science and Technology
International Journal of Machine Learning and Cybernetics | Year: 2014

Approximation capabilities are important and primary properties of neural networks and fuzzy neural networks (FNNs). Neural networks have been successfully applied in many fields since they can work as approximators in nature. Many scholars research FNNs' approximation abilities for continuous fuzzy functions. It is concluded that FNNs can work as approximators for continuous fuzzy functions if the fuzzy functions satisfy some specified conditions. However, the problem whether FNNs can work as approximators for discontinuous fuzzy functions is not solved completely until now. In this work, we focus on the approximation of polygonal FNN for discontinuous fuzzy functions in sense of Choquet integral norms. We first introduce the Choquet integral norms in sub-additive fuzzy measure. Then the universal approximation of polygonal FNNs for fuzzy valued functions in sense of Choquet integral norms is analyzed in this paper. It is proved that the polygonal FNNs can work as approximators for fuzzy valued functions in the sense of Choquet integral norms with respect to sub-additive fuzzy measure. © 2013 Springer-Verlag Berlin Heidelberg.


Zhang C.,Nanjing University of Science and Technology | Wu D.,Wuhan University
Electronic Library | Year: 2012

Purpose - Terminology is the set of technical words or expressions used in specific contexts, which denotes the core concept in a formal discipline and is usually applied in the fields of machine translation, information retrieval, information extraction and text categorization, etc. Bilingual terminology extraction plays an important role in the application of bilingual dictionary compilation, bilingual ontology construction, machine translation and cross-language information retrieval etc. This paper aims to address the issues of monolingual terminology extraction and bilingual term alignment based on multi-level termhood. Design/methodology/approach - A method based on multi-level termhood is proposed. The new method computes the termhood of the terminology candidate as well as the sentence that includes the terminology by the comparison of the corpus. Since terminologies and general words usually have different distribution in the corpus, termhood can also be used to constrain and enhance the performance of term alignment when aligning bilingual terms on the parallel corpus. In this paper, bilingual term alignment based on termhood constraints is presented. Findings - Experimental results show multi-level termhood can get better performance than the existing method for terminology extraction. If termhood is used as a constraining factor, the performance of bilingual term alignment can be improved. Originality/value - The termhood of the candidate terminology and the sentence that includes the terminology is used for terminology extraction, which is called multi-level termhood. Multi-level termhood is computed by the comparison of the corpus. Bilingual term alignment method based on termhood constraint is put forward and termhood is used in the task of bilingual terminology extraction. Experimental results show that termhood constraints can improve the performance of terminology alignment to some extent. © Emerald Group Publishing Limited.


Bao B.C.,Jiangsu Teachers University of Technology | Liu Z.,Nanjing University of Science and Technology | Xu J.P.,Southwest Jiaotong University
Electronics Letters | Year: 2010

By replacing Chua's diode in the canonical Chua's oscillator with a smooth flux-controlled memristor, a memristor based oscillator is presented. The memristor oscillator generates a steady periodic orbit and has a transition from transient chaotic to steady periodic behaviour. The complicated dynamical behaviour is extremely dependent on the initial condition of the memristor. © 2010 The Institution of Engineering and Technology.


Li X.,Nanjing University of Aeronautics and Astronautics | Li X.,Nanjing University of Science and Technology | Liu Y.,Nanjing University of Aeronautics and Astronautics | Liu Y.,Nanjing University of Science and Technology | And 6 more authors.
Angewandte Chemie - International Edition | Year: 2015

As an important energy-saving technique, white-light- emitting diodes (W-LEDs) have been seeking for lowcost and environment-friendly substitutes for rare-earth-based expensive phosphors or Pd2+/Cd2+-based toxic quantum dots (QDs). In this work, precursors and chemical processes were elaborately designed to synthesize intercrossed carbon nanorings (IC-CNRs) with relatively pure hydroxy surface states for the first time, which enable them to overcome the aggregationinduced quenching (AIQ) effect, and to emit stable yelloworange luminescence in both colloidal and solid states. As a direct benefit of such scarce solid luminescence from carbon nanomaterials, W-LEDs with color coordinate at (0.28, 0.27), which is close to pure white light (0.33, 0.33), were achieved through using these low-temperature-synthesized and toxic ion-free IC-CNRs as solid phosphors on blue LED chips. This work demonstrates that the design of surface states plays a crucial role in exploring new functions of fluorescent carbon nanomaterials. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.


Ding Y.,Nanjing University of Science and Technology | Wang P.,China First Metallurgical Construction Co. | Yu S.,Nanjing University of Science and Technology
Measurement: Journal of the International Measurement Confederation | Year: 2015

This paper introduces a new monitoring technology which is characterized by the use of distributed sensing optical fiber to monitor the deformation state of the SMW pile under the stress. With distributed sensing optical fiber attached to the surface inside it, the H-pile is transformed into a pile that has self-sensing capacity. The transformation enables the H-pile to automatically acquire force deformation data such as H-pile flange strain, bending moment, and horizontal displacement. Through the analysis of the H-pile's force structure, a certain method of continuously calculating the pile bending moment, is proposed, with no need to determine the neutral axis' place, and thus achieving temperature self-compensation in the pile measurement. This kind of technology referred to above has been applied in some foundation pit engineering and achieved great success. © 2015 Elsevier Ltd. All rights reserved.


Hu K.,University of New Brunswick | Chen Z.,University of New Brunswick | Fu J.,University of New Brunswick | Fu J.,Nanjing University of Science and Technology
Composite Structures | Year: 2014

The dynamic response of an interface crack between magnetoelectroelastic and functionally graded elastic layers under anti-plane shear and in-plane electric and magnetic impacts is investigated by the integral transform method. Fourier and Laplace transforms are applied to reduce the mixed boundary value problem of the interface crack to dual integral equations, which are expressed in terms of a Fredholm integral equation of the second kind. The singular stress, electric displacement and magnetic induction fields near the crack tip are obtained asymptotically, and the stress intensity factors (SIFs), electric displacement intensity factors (EDIFs) and magnetic induction intensity factors (MIIFs) are determined accordingly. Laplace inverse transform is applied to get the field intensities in time domain. Numerical results show how the dynamic SIF is influenced by the magnetoelectric interactions, the material properties, the electric and magnetic loadings, and the geometric size ratios and the functionally graded parameter. © 2013 Elsevier Ltd.


Fang D.,Jiangsu Provincial Key Laboratory of Coast Wetland Bioresources and Environment Protection | Zhang H.-B.,Jiangsu Provincial Key Laboratory of Coast Wetland Bioresources and Environment Protection | Liu Z.-L.,Nanjing University of Science and Technology
Journal of Heterocyclic Chemistry | Year: 2010

(Chemical Equation Presented) Some halogen-free acyclic task-specific ionic liquids (TSILs) were synthesized as novel and recyclable catalysts for the synthesis of 5-oxo-5,6,7,8-tetrahydro-4H-benzo[b]pyrans by one-pot three-component condensation of aromatic aldehyde, malononitrile (or ethyl cyanoacetate), and dimedone (or 1,3-cyclohexanedione) in water. The condensation accomplished successfully with good yields ranged from 86 to 94%. After the reaction, the products could simply be separated from the catalyst/water, and the catalyst could be reused at least 10 times without noticeably decreasing the catalytic activity. © 2009 HeteroCorporation.


He C.,East China Jiaotong University | Ye Y.,Nanjing University of Science and Technology
International Journal of Intelligent Systems | Year: 2011

We present two fuzzy conjugate gradient learning algorithms based on evolutionary algorithms for polygonal fuzzy neural networks (PFNN). First, we design a new algorithm, fuzzy conjugate algorithm based on genetic algorithm (GA). In the algorithm, we obtain an optimal learning constant η by GA and the experiment indicates the new algorithm always converges. Because the algorithm based on GA is a little slow in every iteration step, we propose to get the learning constant η by quantum genetic algorithm (QGA) in place of GA to decrease time spent in every iteration step. The PFNN tuned by the proposed learning algorithm is applied to approximation realization of fuzzy inference rules, and some experiments demonstrate the whole process. © 2011 Wiley Periodicals, Inc.


Zhu C.,University of Minnesota | Zhu C.,Nanjing University of Science and Technology | Yoshimura A.,University of Minnesota | Ji L.,University of Minnesota | And 3 more authors.
Organic Letters | Year: 2012

The preparation, X-ray structure, and reactivity of new, highly soluble, and reactive iodonium ylides derived from malonate methyl ester and bearing an ortho substituent on the phenyl ring are reported. These new reagents show higher reactivity than common phenyliodonium ylides in the Rh-catalyzed cyclopropanation, C-H insertion, and transylidation reactions under homogeneous conditions. © 2012 American Chemical Society.


Bao B.,Changzhou University | Zhou G.,Southwest Jiaotong University | Xu J.,Southwest Jiaotong University | Liu Z.,Nanjing University of Science and Technology
IEEE Transactions on Power Electronics | Year: 2011

With the variation of circuit parameters, the operation-state regions of current-mode-controlled switching dc-dc converters can shift among stable period region, robust chaos region in continuous conduction mode, and intermittent chaos region in discontinuous conduction mode. This paper presents a unified approach to the operation-states analysis of switching dc-dc converters with ramp compensation. The piecewise map model of the converters is first derived. With the bifurcation analyses, two boundary classification equations of the orbit state shifting are then obtained. Finally, the operation-state regions are well classified. To verify the theoretical analysis results, 2-D bifurcation diagrams are simulated and experimentations with current-mode-controlled buck converter are conducted. It is revealed that regular and irregular (chaotic or intermittent) operation states can be generated depending on circuit parameters or control of ramp-compensation current. © 2011 IEEE.


Ding H.-X.,Nanjing University of Science and Technology | Ding H.-X.,Lianyungang Teachers College | Shen Z.-H.,Nanjing University of Science and Technology | Ni X.-W.,Nanjing University of Science and Technology | Zhu X.-F.,Huazhong University of Science and Technology
Applied Physics Letters | Year: 2012

The authors have demonstrated the multi-splitting and self-similarity of the band gap structures in quasi-periodic plates of Cantor series. The splitting peaks give the regularity of tri-branching. A semi-quantitative explanation is proposed in which the inherent cavity-like structure is proven to play the essential role in the phenomena of multi-splitting and self-similarity, which gives a reliable way to predict where and how the band gap is splitting in the quasi-periodic systems. Possible applications are discussed. © 2012 American Institute of Physics.


Shi X.,Nanjing University of Science and Technology | Shi X.,Nanjing Institute of Technology | Chang S.,Nanjing University of Science and Technology
Mechatronics | Year: 2013

An extended state observer-based time-optimal control is proposed in this paper to achieve fast and precise point-to-point motions driven by a novel electromagnetic linear actuator. Working principle and characteristics of the actuator are analyzed. Total disturbance is estimated by an extended state observer, and the nonlinear system is compensated as a linear one. Time-optimal control is used to realize accurate point-to-point motions with minimal time. Comparative simulations and experimental results demonstrate the effectiveness of the proposed method, especially for non-repetitive point-to-point motions, and good positioning performance has been achieved in the presence of both model uncertainties and external disturbances. © 2013 Elsevier Ltd. All rights reserved.


Bao B.-C.,Jiangsu Teachers University of Technology | Xu J.-P.,Southwest Jiaotong University | Liu Z.,Nanjing University of Science and Technology
Chinese Physics Letters | Year: 2010

Unlike conventional chaotic systems, a memristor based chaotic circuit has an equilibrium set, whose stability is dependent on the initial state of the memristor. The initial state dependent dynamical behaviors of the memristor based chaotic circuit are investigated both theoretically and numerically. © 2010 Chinese Physical Society and IOP Publishing Ltd.


Zhu W.,Nanjing University of Science and Technology | Zhu W.,Beijing Institute of Technology | Xiao H.,Nanjing University of Science and Technology
Journal of Physical Chemistry C | Year: 2011

Ab initio molecular dynamics simulations have been performed to study the effects of different temperatures on the structure and stability of energetic solid silver azide. The results indicate that the N-N bond fission takes place at 523 K. The azide sublattice structure broke down prior to the silver sublattice. The initiation decomposition of silver azide is triggered by the N-N bond breaking. This will initiate many decomposition reactions and produce many nitrogen radicals, N2, and silver clusters. Silver azide has metallic properties at 573 K. As the temperature increases, its sensitivity becomes more and more sensitive. The calculated power spectra of the velocity autocorrelation function show that the low-frequency vibrational modes become more prominent than the high-frequency ones with increasing temperature. This would allow low-frequency vibrations and rotations to occur more freely than in the solid. © 2011 American Chemical Society.


Wang K.,Nanjing University of Science and Technology | Chen M.Z.Q.,University of Hong Kong | Hu Y.,Nanjing University of Science and Technology
Journal of the Franklin Institute | Year: 2014

In this paper, we consider the passive network synthesis problem of biquadratic impedances with at most four elements, motivated by the passive mechanical control. In order to solve this problem, a necessary and sufficient realizability condition for no more than three elements is obtained by some topological properties derived previously. Furthermore, the constraints on the possible realizations are used to derive the networks which can cover all the cases, and they are classified as several quartets. Through investigating one of the networks in each quartet, we obtain a necessary and sufficient condition for any biquadratic impedance to be realizable with at most four elements. Finally, the interlocking conditions are illustrated graphically, and numerical examples are given. © 2013 The Franklin Institute. Published by The Franklin Institute. All rights reserved.


Lu J.,University of Iowa | Yang G.,Nanjing University of Science and Technology | Ge J.,Nanjing University of Science and Technology
Computer Methods in Applied Mechanics and Engineering | Year: 2013

This article introduces a method for blending NURBS with Lagrangian representations in isogeometric analysis. In the blended representation, selected boundary edges or surfaces of a multivariate NURBS patch are parameterized in (rational) Lagrangian form. Lagrangian parameters are obtained by transforming the NURBS representation. The transformation, by construction, exactly preserves the original geometry. The transformation method is described in detail. In analysis, the blended form is useful for interfacing NURBS domains to finite element domains, or for imposing essential boundary conditions. The application is demonstrated using numerical examples. © 2013 Elsevier B.V..


Chen M.Z.Q.,University of Hong Kong | Wang K.,Nanjing University of Science and Technology | Shu Z.,University of Southampton | Li C.,CAS Academy of Mathematics and Systems Science
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2013

This paper investigates the simplified realization problem of a special class of positive-real admittances similar to biquadratic functions but with an extra pole at the origin, which is widely used in the analysis of suspension systems. The results in this paper are motivated by passive mechanical control with the inerter. The concept of strictly lower complexity is first defined, whose indices in this paper are the total number of elements, the number of resistors (dampers), and the number of capacitors (inerters). We then derive a necessary and sufficient condition for this class of admittance to be realized by the networks that are of strictly lower complexity than the canonical realization by the Foster Preamble method. To solve this problem, it is shown that it suffices to consider the following: 1) networks with at most four elements, 2) irreducible five-element resistor-inductor (RL) networks, and 3) irreducible five-element resisitor-inductor-capacitor (RLC) networks. Other cases are shown to be impossible. By finding their corresponding network configurations through a series of constraints and deriving the corresponding realizability conditions, the final condition can be obtained. Finally, the U-V plane and numerical examples are provided to illustrate the theoretical results. © 2004-2012 IEEE.


Wang K.,Nanjing University of Science and Technology | Chen M.Z.Q.,University of Hong Kong
IEEE Transactions on Circuits and Systems II: Express Briefs | Year: 2012

This brief is concerned with the realization problem of biquadratic impedances, motivated by the recent development in passive mechanical control. This brief generalizes a realization procedure of a special class of biquadratic impedances to a more general form, and the resulting series-parallel RLC networks whose elements are no more than those in Bott-Duffin's networks are obtained without minimization. The realizability condition is proven by providing a constructive synthesis procedure. The series-parallel network obtained contains elements no more than those of Bott-Duffin's network when the impedance is nonregular. © 2004-2012 IEEE.


Xiong P.,University of Texas at Austin | Xiong P.,Nanjing University of Science and Technology | Liu B.,University of Texas at Austin | Teran V.,University of Texas at Austin | And 4 more authors.
ACS Nano | Year: 2014

Hybrid inorganic/graphene two-dimensional (2D) nanostructures can offer vastly open large surface areas for ion transport and storage and enhanced electron transport, representing a promising material platform for next-generation energy storage. Here we report chemically integrated hybrid ZnMn2O4/graphene nanosheets synthesized via a facile two-step method for greatly enhanced lithium storage capability. The hybrid 2D nanosheets are composed of ultrafine ZnMn2O4 nanocrystals with a mean diameter of ∼4 nm attached to and well dispersed on the surface of reduced graphene oxide sheets. The hybrid nanosheets based anode offers a high capacity of ∼800 mAh g-1 at a current rate of 500 mA g -1, excellent rate capability, and long-term cyclability with reversible capacity of ∼650 mAh g-1 over 1500 cycles at a current density of 2000 mA g-1. Moreover, when tested in a temperature range of ∼0-60 °C, the designed anode can maintain high discharge capacities from 570 to 820 mAh g-1. © 2014 American Chemical Society.


Xu J.,Nanjing University of Science and Technology | Xu J.,Shaoguan University | Yang J.,Nanjing University of Science and Technology
Neurocomputing | Year: 2013

This paper presents a new classification technique by combining the well-known Sparse Representation based algorithm with the theory of Fuzzy Set. The basic idea of this work is that samples with the same class-labels should be more similar to each other than those with different class-labels. Based on this similarity rule, we first impose the nonnegative coefficient constraints on the sparse representation based algorithm and obtain the desirable similar neighbors. Then by introducing the theory of Fuzzy Set into our work, we construct the fuzzy class membership matrix and then assign the decision membership of the query sample to each class. The class assigned with the dominant decision membership is wanted. The proposed approach is called the Nonnegative Sparse Representation based Fuzzy Similar Neighbor Classification (FSNC). FSNC has the following properties: (a) the neighbor parameter K is not needed to be set in advance, and K is adaptively set by the algorithm itself; (b) similar neighbors are also generated adaptively and contain much more similar properties of the query sample; (c) the degree of similarity of data is clearly recorded in the sparse nonnegative coefficient vector; (d) the fuzzy decision rule is effective and the proposed classifier FSNC is simple. Experimental results conducted on the Wine database from UCI, the AR face database, the CENPARMI handwritten numeral database, and the PolyU palmprint database show that the new proposed classification technique outperforms some other state-of-the-art classifiers. © 2012 Elsevier B.V.


Du B.,Nanjing University of Science and Technology | Lam J.,University of Hong Kong | Shu Z.,University of Southampton
IET Control Theory and Applications | Year: 2012

This study addresses the strong stabilisation problem for continuous-time linear systems with an unknown input delay via dynamic output feedback controllers. A new criterion for dynamic output feedback stabilisability is proposed in terms of matrix inequalities with the separation of the controller gain with the Lyapunov matrix and the system matrices. Based on these new characterisations, an iterative algorithm is given to design the dynamic output feedback controllers with the initial values obtained by some proposed state feedback stabilisation methods. The effectiveness and merits of the proposed approach are shown through several examples. © 2012 The Institution of Engineering and Technology.


Zuo C.,Nanjing University of Science and Technology | Zuo C.,Nanyang Technological University | Zuo C.,Beijing Institute of Technology | Chen Q.,Nanjing University of Science and Technology | And 3 more authors.
Optics Express | Year: 2013

We present a high-speed transport-of-intensity equation (TIE) quantitative phase microscopy technique, named TL-TIE, by combining an electrically tunable lens with a conventional transmission microscope. This permits the specimen at different focus position to be imaged in rapid succession, with constant magnification and no physically moving parts. The simplified image stack collection significantly reduces the acquisition time, allows for the diffraction-limited through-focus intensity stack collection at 15 frames per second, making dynamic TIE phase imaging possible. The technique is demonstrated by profiling of microlens array using optimal frequency selection scheme, and time-lapse imaging of live breast cancer cells by inversion the defocused phase optical transfer function to correct the phase blurring in traditional TIE. Experimental results illustrate its outstanding capability of the technique for quantitative phase imaging, through a simple, non-interferometric, high-speed, high-resolution, and unwrapping-free approach with prosperous applications in micro-optics, life sciences and bio-photonics. ©2013 Optical Society of America.


Zhang B.,Nanjing University of Science and Technology | Lam J.,University of Hong Kong | Xu S.,Nanjing University of Science and Technology
Journal of the Franklin Institute | Year: 2014

This paper is concerned with the problems of reachable set estimation and state-feedback controller design for linear systems with distributed delays and bounded disturbance inputs. The disturbance inputs are assumed to be either unit-energy bounded or unit-peak bounded. First, based on the Lyapunov-Krasovskii functional approach and the delay-partitioning technique, delay-dependent conditions for estimating the reachable set of the considered system are derived. These conditions guarantee the existence of an ellipsoid that contains the system state under zero initial conditions. Second, the reachable set estimation is taken into account in the controller design. Here, the purpose is to determine an ellipsoid and find a state-feedback controller such that the determined ellipsoid contains the reachable set of the resulting closed-loop system. Sufficient conditions for the solvability of the control synthesis problem are obtained. Based on these results, the problem of how to design a controller such that the state of the resulting closed-loop system is contained in a prescribed ellipsoid is studied. Finally, numerical examples and simulation results are provided to show the effectiveness of the proposed analysis and design methods. © 2014 The Franklin Institute.


Du B.,Nanjing University of Science and Technology | Lam J.,University of Hong Kong | Zou Y.,Nanjing University of Science and Technology | Shu Z.,University of Southampton
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2013

This paper focuses on the stability analysis and controller synthesis of continuous-time Markovian jump time-delay systems with incomplete transition rate descriptions. A general stability criterion is formulated first for state-and input-delay Markovian jump time-delay systems with fully known transition rates. On the basis of the proposed condition, an equivalent condition is given under the assumption of partly known/unknown transition rates. A new design technique based on a projection inequality has been applied to design both state feedback and static output feedback controllers. All conditions can be readily verified by efficient algorithms. Finally, illustrative examples are provided to show the effectiveness of the proposed approach. © 2004-2012 IEEE.


Xia Y.,Beijing Institute of Technology | Pu F.,Beijing Institute of Technology | Fu M.,Nanjing University of Science and Technology | Ye L.,Beijing Institute of Technology
IEEE Transactions on Industrial Electronics | Year: 2016

In this paper, the modeling and tracking control problem of unmanned turret system (UTS) is addressed. To guarantee the feasibility of modeling and control, three-axis stabilization is analyzed. A complete mathematical model for UTS is then established based on robotic analysis technique. The coupling model also takes inner parameters perturbation and external disturbances into consideration. To achieve rapid response and high tracking precision, a fast nonsingular terminal sliding mode control scheme is designed compounding with extended state observer (ESO). Owing to the estimating ability of ESO, this control scheme can reduce the chattering phenomena remarkably. Finally, simulation results are presented to illustrate effectiveness of the control strategies. © 1982-2012 IEEE.


Xu C.,Fuzhou University | Wang X.,Nanjing University of Science and Technology
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2012

Graphene oxide sheets have been used as a kind of plane stabilizing agent to prepare Ag nanoparticle colloids. The utilization of graphene oxide has effects on the size of Ag nanoparticles and can enhance the stability of the as-prepared colloids. These graphene oxide stabilized Ag nanoparticles possess relatively uncapped surface, which behave good catalysis activity. Furthermore, we also prepared graphene oxide-mediated Au and Pt nanoparticle colloids through galvanic replacement reactions using graphene oxide-Ag nanoparticles as templates. © 2012 Elsevier B.V.


Dou L.,Nanjing University of Science and Technology | Dou J.,China Academy of Space Technology
IEEE Transactions on Advanced Packaging | Year: 2010

This paper applies the LaxFriedrichs technique, usually used in fluid dynamics, to transmission line sensitivity analysis. The LaxFriedrichs difference scheme for sensitivity analysis of both uniform and nonuniform transmission lines is derived. Based on this scheme, a method for analyzing multiconductor transmission line sensitivity, which does not need to be decoupled, is presented by combining with matrix operations. Using numerical experiments, the proposed method is compared with the characteristic method and the fast Fourier transform approach. With the presented method, the sensitivity of a nonlinear circuit including nonuniform multiconductor transmission lines is analyzed and the results are verified by the HSPICE perturbation method. The proposed method can be applied to either linear or nonlinear circuits, which include lossy nonuniform multiconductor transmission lines, and is proved to be efficient. © 2006 IEEE.


Hu Y.,Nanjing University of Science and Technology | Chen M.Z.Q.,University of Hong Kong | Shu Z.,University of Southampton
Journal of Sound and Vibration | Year: 2014

This paper investigates passive vehicle suspensions with inerters by considering multiple performance requirements including ride comfort, suspension deflection and tyre grip, where suspension deflection performance is novelly considered which is formulated as a part of objective functions and a constraint separately. Six suspension configurations are analyzed and the analytical solutions for each performance measure are derived. The conditions for each configuration to be strictly better than the simpler ones are obtained by presenting the analytical solutions of each configuration based on those of the simpler ones. Then, two stages of comparisons are given to show the performance limitations of suspension deflection for passive suspensions with inerters. In the first stage, it is shown that although the configurations with inerters can improve the mixed performance of ride comfort and tyre grip, the suspension deflection performance is significantly decreased simultaneously. In the second stage, it is shown that for passive suspensions with inerters, suspension deflection is the more basic limitation for both ride comfort and tyre grip performance by doing comparisons among mixed ride comfort and suspension deflection optimization, mixed ride comfort and tyre grip optimization, and mixed suspension deflection and tyre grip optimization. Finally, the problem of mixed ride comfort and tyre grip performance optimization with equal suspension deflection is investigated. The limitations of suspension deflection for each configuration are further highlighted. © 2013 Elsevier Ltd. All rights reserved.


Zhang Y.,Nanjing University of Science and Technology | Xu S.,Nanjing University of Science and Technology | Chu Y.,Huzhou Teachers College
International Journal of Robust and Nonlinear Control | Year: 2012

This paper proposes a sliding mode observer-controller design method for uncertain Markovian jump systems with time delays and uncertain switching probabilities. Both the structures of a sliding mode observer and a sliding mode controller are given. By the mode-dependent Lyapunov functional approach, a sufficient condition for the stochastic stability of the closed-loop system is given, which can be converted into a convex optimization problem. The reachability of the sliding surfaces in both the estimation error space and the state estimate space can be ensured by the presented control scheme. Finally, the effectiveness of the proposed design method is demonstrated by a simulation example. © 2011 John Wiley & Sons, Ltd.


Chen M.Z.Q.,University of Hong Kong | Wang K.,Nanjing University of Science and Technology | Zou Y.,Nanjing University of Science and Technology | Lam J.,University of Hong Kong | Lam J.,Nanjing University of Science and Technology
IEEE Transactions on Automatic Control | Year: 2013

In this note, we investigate the realization problem of a special class of positive-real admittances, which is common in vehicle suspension designs. The number of inerters and dampers is restricted to one in each case and the number of the springs is arbitrary. To solve the problem, we first convert a previous result by to a more direct form. A necessary and sufficient condition for realizability is then derived and explicit circuit arrangements are provided by assuming that the three-port network consisting of only springs after extracting the damper and the inerter has a well-defined impedance. To remove the assumption on the existence of a well-defined impedance, a condition is established on the topological property of the $n$-port network without a well-defined impedance to obtain an equivalent class of such networks so that the realizability condition is derived with realization. By combining the conditions with and without a well-defined impedance, the final realization result is obtained. © 1963-2012 IEEE.


Lam J.,University of Hong Kong | Zhang B.,Nanjing University of Science and Technology | Chen Y.,University of Hong Kong | Xu S.,Nanjing University of Science and Technology
International Journal of Robust and Nonlinear Control | Year: 2015

This paper is concerned with the reachable set estimation problem for discrete-time linear systems with multiple constant delays and bounded peak inputs. The objective is to check whether there exists a bounded set that contains all the system states under zero initial conditions. First, delay-dependent conditions for the solvability of the addressed problem are derived by employing a novel Lyapunov-Krasovskii functional. The obtained conditions are expressed in terms of matrix inequalities, which are linear when only one scalar variable is fixed. On the basis of these conditions, an ellipsoid containing the reachable set of the considered system is obtained. An approach for determining the smallest ellipsoid is also provided. Second, the approach and results developed in the first stage are generalized to the case of systems with polytopic parameter uncertainties, and delay-dependent conditions are given in the form of relaxed matrix inequalities. Finally, two numerical examples are provided to demonstrate the effectiveness of the proposed methods. Copyright © 2013 John Wiley & Sons, Ltd. Copyright © 2013 John Wiley & Sons, Ltd.


Zhang B.,Nanjing University of Science and Technology | Xu S.,Nanjing University of Science and Technology | Lam J.,University of Hong Kong
Neurocomputing | Year: 2014

This paper revisits the problem of passivity analysis for neural networks with time-varying delays. A new delay-dependent criterion is obtained in terms of linear matrix inequalities, guaranteeing that the input and output of the considered neural network satisfy a prescribed passivity-inequality constraint. This newly presented criterion does not require all the symmetric matrices involved in the employed quadratic Lyapunov-Krasovskii functional to be positive definite. This feature is remarkable since it sheds new light on the traditional ideas for constructing Lyapunov-Krasovskii functionals. More importantly, the conservatism of delay-dependent passivity conditions can be reduced due to the relaxation on the positive-definiteness of every Lyapunov matrix. It is shown both theoretically and numerically that the passivity criterion proposed in this paper is truly less conservative than some of the latest results in the literature. © 2014 Elsevier B.V.


Li L.,Nanjing University of Science and Technology | Yang J.,Yingyeda Electronics Company | Zhong Q.,Delta Electronics Inc
IEEE Transactions on Power Electronics | Year: 2011

The capacitor-clamped base cell is presented. Based on the base cell, a novel family of single-stage three-level (TL) ac choppers is proposed. The converters can directly transfer unsteady high ac voltage with distortion into regulated sinusoidal voltage with low THD. The circuit configuration is constituted of a TL converter, and input and output filters. The topological family includes buck, boost, buckboost, Cuk, Sepic, and Zeta modes. In order to achieve a reliable TL ac-ac conversion, a double transient voltage feedback control strategy of output voltage and the voltage across the clamp capacitor is introduced in this paper. A prototype of a 500 VA 220 V ± 10% 50 Hz ac/180-240 V 50 Hz ac converter is presented with the experimental results to prove that the converters have four improved advantages simultaneously, including the lower voltage stress of power switches, the bidirectional power flow, the low total harmonic distortion of output voltage, and the higher input power factor. © 2006 IEEE.


Zhang B.,Nanjing University of Science and Technology | Li Y.,Huzhou Teachers College
Signal Processing | Year: 2013

This paper is concerned with the problem of exponential L2- L∞ filter design for linear systems simultaneously with distributed delays, Markovian jumping parameters and norm-bounded parametric uncertainties. The purpose is to design full-order mode-dependent filters such that the filtering error system is not only mean-square robustly exponentially stable with a specified decay rate but also satisfies an L2- L∞ performance requirement. First, sufficient conditions for the stability and performance analysis of the filtering error system are derived based on a novel version of mode-dependent Lyapunov-Krasovskii functional. Then, delay-dependent and decay-rate-dependent conditions for the existence of desired filters are obtained in terms of linear matrix inequalities (LMIs). The filter coefficients can be computed by using feasible solutions of the presented LMIs. Finally, a numerical example is provided to demonstrate the effectiveness of the proposed design method. © 2012 Elsevier B.V.


Tang L.,Nanjing Pengtu Power Supply Co., Ltd | Wu J.,Nanjing University of Science and Technology
Dianwang Jishu/Power System Technology | Year: 2012

At present the phasor measurement unit (PMU) based on clock synchronization technology becomes an important technical means to observe dynamic behavior of power system directly. When power system is in the N-1 failure state, traditional configuration of PMU cannot meet the demand of "whole system observable". If the condition of N-1 failure state is taken into account during the configuration of PMU, more PMUs should be configured than traditional configuration and the cost for the configuration will evidently increase. In allusion to it, a new optimal scheme for PMU configuration is proposed. Firstly, the vulnerability of power system and its branches is analyzed by generalized Tellegen's theorem; then the PMU configuration of the whole system and the PMU configuration considering N-1 failure state are performed; finally through the sorting of vulnerability and analyzing economic index and robustness, the configuration of PMU is determined. The feasibility of the proposed method is verified by simulation results of IEEE 14-bus system.


Doan M.T.,Nanjing University of Science and Technology | Doan M.T.,Hanoi University | Che W.Q.,Nanjing University of Science and Technology | Feng W.J.,Nanjing University of Science and Technology
Electronics Letters | Year: 2012

A tri-band bandpass filter (BPF) using square ring short stub loaded resonators (SRSLR) is presented. The characteristics of the triple-mode resonator are investigated by using even/odd mode analysis. The centre frequencies of the first three passbands can be independently controlled by tuning the dimensions of the SRSLR. Moreover, the filter has been implemented with eight transmission zeros to improve the selectivity. A prototype of a tri-band BPF centred at 2.4, 3.5 and 5.2GHz has been designed and fabricated. Good agreement can be found between the measured and simulated results. © 2012 The Institution of Engineering and Technology.


Mao Y.,University of Electronic Science and Technology of China | Zhang H.,University of Electronic Science and Technology of China | Xu S.,Nanjing University of Science and Technology
IEEE Transactions on Fuzzy Systems | Year: 2014

In this paper, we investigate the problem of exponential stability and asynchronous stabilization for a class of switched nonlinear systems. The Takagi and Sugeno (T-S) fuzzy model is employed to approximate the subnonlinear dynamic systems. With two-level functions, namely, crisp switching functions and local fuzzy weighting functions, we introduce continuous-time switched fuzzy systems, which inherently contain the features of the switched hybrid systems and T-S fuzzy systems. By the use of delicately constructed piecewise Lyapunov-like functions (PLFs) and minimum dwell time method, we obtain the exponential stability of the switched fuzzy systems, which allows us to have stable and unstable nonlinear subsystems. In practice, for the control problem, it inevitably takes some time to identify the system modes and apply the matched controller, the asynchronous phenomena between the system modes switching and the controllers switching generally exists. Based on the result of stability, the fuzzy state feedback controller under asynchronous switching is proposed for switched fuzzy systems. In addition, the lower bound of minimum dwell time can be obtained using convex optimization such that the switched fuzzy system can be exponentially stabilized if its minimum dwell time is larger than the bound. The stability results and control laws of the switched fuzzy systems are formulated in the form of linear matrix inequalities that are numerically feasible. Finally, two illustrated numerical examples are presented to show the effectiveness of the obtained theoretical results. © 1993-2012 IEEE.


Xia H.,Nanjing University of Science and Technology | Meng Y.S.,University of California at San Diego | Li X.,Dalian University of Technology | Yuan G.,Nanjing University of Science and Technology | Cui C.,Nanjing University of Science and Technology
Journal of Materials Chemistry | Year: 2011

For manganese oxides with low manganese oxidation states, such as MnO or Mn3O4, the electrochemical oxidation during potential cycling is critical to achieve high supercapacitor performance. In this work, dense Mn3O4 thin films are prepared by pulsed laser deposition. An electrochemical lithiation/delithiation process is applied to the Mn3O4 thin film, which leads to a nanoporous structure of the film and greatly increases the porosity of the film. The nanoporous MnOx thin film electrode exhibits significantly improved supercapacitive performance compared to the as-prepared Mn3O 4 thin film electrode. After 1000 cyclic voltammetric scans in 1 M Na2SO4 electrolyte between 0 and 1 V, only part of the surface of the as-prepared Mn3O4 thin film transforms into a MnO2 porous structure while the complete film of the nanoporous MnOx transforms into a MnO2 porous structure. It is believed that the nanoporous structure, which facilitates the electrolyte penetration, leads to the completion of electrochemical oxidation through the film during the potential cycling, resulting in promising supercapacitive performance of the film. © 2011 The Royal Society of Chemistry.


Song J.,Nanjing University of Aeronautics and Astronautics | Song J.,Nanjing University of Science and Technology | Li J.,Nanjing University of Science and Technology | Xu J.,Shanghai Institute of Technology | And 2 more authors.
Nano Letters | Year: 2014

Low cost and high conductivity make copper (Cu) nanowire (NW) electrodes an attractive material to construct flexible and stretchable electronic skins, displays, organic light-emitting diodes (OLEDs), solar cells, and electrochromic windows. However, the vulnerabilities that Cu NW electrodes have to oxidation, bending, and stretching still present great challenges. This work demonstrates a new Cu@Cu4Ni NW conductive elastomer composite with ultrahigh stability for the first time. Cu@Cu4Ni NWs, facilely synthesized through a one-pot method, have highly crystalline alloyed shells, clear and abrupt interfaces, lengths more than 50 μm, and smooth surfaces. These virtues provide the NW-elastomer composites with a low resistance of 62.4 ohm/sq at 80% transparency, which is even better than the commercial ITO/PET flexible electrodes. In addition, the fluctuation amplitude of resistance is within 2 ohm/sq within 30 days, meaning that at ΔR/R0 = 1, the actual lifetime is estimated to be more than 1200 days. Neither the conductivity nor the performances of OLED with elastomers as conductive circuits show evident degradation during 600 cycles of bending, stretching, and twisting tests. These high-performance and extremely stable NW elastomeric electrodes could endow great chances for transparent, flexible, stretchable, and wearable electronic and optoelectronic devices. © 2014 American Chemical Society.


Pei H.,CAS Shanghai Institute of Applied Physics | Li F.,CAS Shanghai Institute of Applied Physics | Wan Y.,Nanjing University of Science and Technology | Wei M.,CAS Shanghai Institute of Applied Physics | And 5 more authors.
Journal of the American Chemical Society | Year: 2012

Conjugates of DNA and gold nanoparticles (AuNPs) typically exploit the strong Au-S chemistry to self-assemble thiolated oligonucleotides at AuNPs. However, it remains challenging to precisely control the orientation and conformation of surface-tethered oligonucleotides and finely tune the hybridization ability. We herein report a novel strategy for spatially controlled functionalization of AuNPs with designed diblock oligonucleotides that are free of modifications. We have demonstrated that poly adenine (polyA) can serve as an effective anchoring block for preferential binding with the AuNP surface, and the appended recognition block adopts an upright conformation that favors DNA hybridization. The lateral spacing and surface density of DNA on AuNPs can also be systematically modulated by adjusting the length of the polyA block. Significantly, this diblock oligonucleotide strategy results in DNA-AuNPs nanoconjugates with high and tunable hybridization ability, which form the basis of a rapid plasmonic DNA sensor. © 2012 American Chemical Society.


Yang X.,Jiangsu University of Science and Technology | Song X.,Jiangsu University of Science and Technology | Chen Z.,Taiyuan University of Technology | Yang J.,Nanjing University of Science and Technology
International Journal of Machine Learning and Cybernetics | Year: 2012

Multigranulation rough set is a new and interesting topic in the theory of rough set. In this paper, the multigranulation rough sets approach is introduced into the incomplete information system. The tolerance relation, the similarity relation and the limited tolerance relations are employed to construct the optimistic and the pessimistic multigranulation rough sets, respectively. Not only the properties about these multigranulation rough sets are discussed, but also the relationships among these multigranulation rough sets models are explored. It is shown that by the multigranulation rough sets theory, the limited tolerance relations based multigranulation lower approximations fall between the tolerance and the similarity relations based multigranulation lower approximations, the limited tolerance relations based multigranulation upper approximations fall between the similarity and the tolerance relations based multigranulation upper approximations. Such results are consistent to those in single-granulation based rough sets models. © 2011 Springer-Verlag.


Wan Y.,Nanjing University of Science and Technology | Su Y.,Nanjing University of Science and Technology | Zhu X.,Nanjing University of Science and Technology | Liu G.,Shanghai Institute of Technology | Fan C.,CAS Shanghai Institute of Applied Physics
Biosensors and Bioelectronics | Year: 2013

Electrochemical immunosensors (EI) has attracted numerous interests due to its inherent benefits over the other transduction schemes, such as a high sensitivity, ease of use, a possible automation and integration in compact analytical devices, mostly cheap and relatively simple technology of its production. Thus, EIs have great potential in point of care (POC) diagnostics for early detection of diseases. During last decades, numerous efforts have been put into EIs development. Firstly, different fabrication methods and amplification strategies have been employed to achieve high sensitivity. To be pointed, nanotechnology has been involved in the fabrication and signal amplification of EIs, which present great superiority. Secondly, EI arrays have been used for multiparametric analysis. Thirdly, several attempts have been made to construct integrated systems, which showed promising applications for POC test. Several of them are commercially available for POC use. Herein, we will review briefly the recent achievements and progress in developing EIs towards POC diagnostics. © 2013 Elsevier B.V.


Gleiter H.,Institute of Nanotechnology | Gleiter H.,Nanjing University of Science and Technology | Schimmel T.,Institute of Nanotechnology | Schimmel T.,Nanjing University of Science and Technology | And 2 more authors.
Nano Today | Year: 2014

It is the aim of this review to discuss the preparation, the atomic structure and the properties of nanometer structured solids that consist either totally or partially of amorphous components. We shall try to present evidence suggesting that it is the variation of the boundary conditions applied for preparing these nano-structures that open the way to a variety of materials with new atomic arrangements/new properties ranging from nano-glasses to switchable atomic quantum transistors. In order to discuss the basic ideas, we shall consider (in the first part of this review) solid materials that are assembled of nanometer-sized crystalline or amorphous building blocks connected by interfaces. The resulting materials are called nano-crystalline materials (nc) and nano-glasses (NG). Nano-crystalline materials and nano-glasses are solid materials composed of nanometer-sized crystalline or nanometer-sized glassy regions connected by crystal/crystal or glass/glass interfaces. As the atomic structures of these interfaces differ from the ones in the building blocks, the atomic and electronic structures of these interfaces differ from the ones in the building blocks. The atomic and the electronic structures (and hence the properties) of nano-crystalline materials and/or nano-glasses differ from the ones of single crystals or of glasses, respectively, that are available today with the same chemical compositions. In the second part of this review solid materials will be discussed the properties of which are controlled by nanometer spaced solid/liquid or solid/gas interfaces. The first group of materials of this kind to be discussed are nano-porous metals with electrolyte or gas filled interconnected nanometer-sized ligaments. The properties of the resulting numerous solid/liquid or solid/gas interfaces may be controlled reversibly by external variables e.g. by applying an external voltage between an aqueous electrolyte in the pores and the nano-porous metal or by varying the chemical composition of the gas in the pores. Due to the high density (∼1015 mm-3) of nano-scale ligaments, the entire nano-porous material reacts and becomes a solid of macroscopic dimensions with tunable mechanical, electric, magnetic, etc. properties. The other group of materials to be discussed in the second section of this review are nanometer-sized single crystals embedded in an aqueous electrolyte. By varying the boundary conditions for the formation of these nanometer-sized crystals, the size, the shape and the electronic structure of these nanometer-sized crystals can be switched reversibly so that switchable quantum transistors are obtained. All of these findings may also be interpreted in a more general context suggesting that in all the above mentioned cases, complex structures evolve if the following four conditions are met: (i) a substrate or nucleation site, on which the structures can organize, (ii) a free volume providing the sterical degrees of freedom for building the new structures, (iii) a reservoir of building blocks (molecules, atoms, ions, crystallites, glassy clusters) from which the structures can be (reversibly or irreversibly) formed and finally (iv) confined geometries preventing the return to thermal equilibrium by preventing the growth of macroscopic single crystals. This general approach seems to open the way for understanding and developing the guidelines for the growth of new self-organized complex material systems far from thermal equilibrium. © 2014 Elsevier Ltd.


Zhao F.,Nanjing Agricultural University | Xie Q.,Nanjing Agricultural University | Xu M.,Nanjing Agricultural University | Wang S.,Nanjing University of Science and Technology | And 2 more authors.
Biosensors and Bioelectronics | Year: 2015

Cyclic adenosine monophosphate (cAMP) is an important small biological molecule associated with the healthy state of living organism. In order to realize highly sensitive and specific detection of cAMP, here an RNA aptamer and electrochemical impedance spectroscopy (EIS) based biosensor enhanced by gold nanoparticles electrodeposited on the surface of gold electrode is designed. The designed aptasensor has a wide effective measuring range from 50. pM to 250. pM with a detection limit of 50. pM in PBS buffer, and an effective measuring range from 50. nM to 1. μM with a detection limit of 50. nM in serum. The designed biosensor is also able to detect cAMP with high sensitivity, specificity, and stability. Since the biosensor can be easily fabricated with low cost and repeatedly used for at least two times, it owns great potential in wide application fields such as clinical test and food inspection, etc. © 2014 Elsevier B.V.


Hao Q.,Nanjing University of Science and Technology | Xia X.,Nanjing University of Science and Technology | Lei W.,Nanjing University of Science and Technology | Wang W.,Nanjing University of Science and Technology | Qiu J.,Dalian University of Technology
Carbon | Year: 2015

The physicochemical property of chemically prepared graphene can be significantly changed due to the incorporating of heteroatoms into graphene. In this article, boron-doped graphene sheets are used as carbon substrates instead of graphene for loading polyaniline by in situ polymerization. Compared with the individual component and polyaniline/nondoped graphene, the sandwich-like polyaniline/boron-doped graphene exhibits remarkably enhanced electrochemical specific capacitance in both acid and alkaline electrolytes. In a three-electrode configuration, the hybrid has a specific capacitance about 406 F g-1 in 1 M H2SO4 and 318 F g-1 in 6 M KOH at 1 mV s-1. In the two-electrode system of a symmetric supercapacitor, this hybrid achieves a specific capacitance about 241 and 189 F g-1 at 0.5 A g-1 with a specific energy density around 19.9 and 30.1 Wh kg-1, in the acid and alkaline electrolytes, respectively. The as-obtained polyaniline/boron-doped graphene hybrid shows good rate performance. Notably, the obtained electrode materials exhibit long cycle stability in both acid and alkaline electrolytes (∼100% and 83% after 5000 cycles, respectively). The improved electrochemical performance of the hybrid is mainly attributed to the introduction of additional p-type carriers in carbon systems by boron-doping and the well combination of pseudocapacitive conducting polyaniline. © 2014 Elsevier Ltd. All rights reserved.


Shi Y.,Nanjing University of Science and Technology | Xia M.-Y.,University of Electronic Science and Technology of China | Chen R.-S.,Nanjing University of Science and Technology | Michielssen E.,University of Michigan | Lu M.,University of Texas at Arlington
IEEE Transactions on Antennas and Propagation | Year: 2011

Prior theoretical studies and experience confirm that the stability of marching-on-in-time (MOT) solvers pertinent to the analysis of scattering from free-standing three-dimensional perfect electrically conducting surfaces hinges on the accurate evaluation of MOT matrix elements resulting from a Galerkin discretization of the underlying time domain integral equation (TDIE). Unfortunately, the accurate evaluation of the four-dimensional spatial integrals involved in the expressions for these matrix elements is prohibitively expensive when performed by computational means. Here, a method that permits the quasi-exact evaluation of MOT matrix elements is presented. Specifically, the proposed method permits the analytical evaluation of three out of the four spatial integrations, leaving only one integral to be evaluated numerically. Since the latter has finite range and a piecewise smooth integrand, it can be evaluated to very high accuracy using standard quadrature rules. As a result, the proposed method permits the fast evaluation of MOT matrix elements with arbitrary (user-specified) accuracy. Extensive numerical experiments show that an MOT solver for the electric field TDIE that uses the proposed quasi-exact method is stable for a very wide range of time step sizes and yields solutions that decay exponentially after the excitation vanishes. © 2010 IEEE.


Zhao J.,Nanjing University of Science and Technology | Wang J.,Nanjing University of Science and Technology | Zhang G.,Nanjing University of Science and Technology | Li J.-L.,University of Electronic Science and Technology of China
IEEE Microwave and Wireless Components Letters | Year: 2013

A new microstrip ultra-wideband (UWB) bandpass filter (BPF) with two sharp notches using E-shaped resonator is proposed in this letter. The circuit topology and its corresponding electrical parameters of the initial microstrip UWB BPF are achieved by a variation of genetic algorithm (GA). Then, the resonance properties of the E-shaped resonator are studied. Results reveal that the multiple-mode property of the E-shaped resonator can be utilized in the UWB BPF design to achieve dual band-notched performance. To validate the design concept, a microstrip UWB BPF with two notched bands respectively centered at frequencies of 5.9 GHz and 8.0 GHz is designed and fabricated. Both simulation and experimental results are provided with good agreement. © 2013 IEEE.


Kuang F.,Nanjing University of Science and Technology | Kuang F.,Hunan Institute of Technology | Xu W.,Nanjing University of Science and Technology | Xu W.,Changsha University of Science and Technology | Zhang S.,Hunan Institute of Technology
Applied Soft Computing Journal | Year: 2014

A novel support vector machine (SVM) model combining kernel principal component analysis (KPCA) with genetic algorithm (GA) is proposed for intrusion detection. In the proposed model, a multi-layer SVM classifier is adopted to estimate whether the action is an attack, KPCA is used as a preprocessor of SVM to reduce the dimension of feature vectors and shorten training time. In order to reduce the noise caused by feature differences and improve the performance of SVM, an improved kernel function (N-RBF) is proposed by embedding the mean value and the mean square difference values of feature attributes in RBF kernel function. GA is employed to optimize the punishment factor C, kernel parameters σ and the tube size É of SVM. By comparison with other detection algorithms, the experimental results show that the proposed model performs higher predictive accuracy, faster convergence speed and better generalization. © 2014 Elsevier B.V.


Fang J.,Novartis | Zhou J.,Novartis | Fang Z.,Nanjing University of Science and Technology
RSC Advances | Year: 2013

An iridium-catalyzed hydrogen transfer reaction was successfully applied in the synthesis of 2-substituted quinazolines in moderate yields starting from aldehydes or alcohols with 2-aminobenzylamines. © 2013 The Royal Society of Chemistry.


Wei T.,Nanjing University of Science and Technology | Wei T.,Wenzhou Medical College | Zhu W.,Nanjing University of Science and Technology | Zhang J.,Wenzhou Medical College | Xiao H.,Nanjing University of Science and Technology
Journal of Hazardous Materials | Year: 2010

The heats of formation (HOFs) for a series of tetrazolo-[1,5-b]-1,2,4,5-tetrazine (TETZ) and 1,2,4-triazolo-[4,3-b]-1,2,4,5-tetrazine (TTZ) derivatives were studied by using density functional theory. The results show that the substitution of the -N3 or -N(NO2)2 group in the TETZ or TTZ ring extremely enhances its HOF values. For monosubstituted case, attachment of a substituent to position 8 in the TETZ or TTZ ring will increase its energy gaps except for the derivatives with the -NO2 group. It is also found that the energy gap of TTZ can be tuned by incorporating a substituent into different positions in the parent ring. The substitution of the -NH2 group in the TETZ ring is favorable for enhancing its thermal stability. For the TTZ ring, different substituted positions and number of the substituent might affect its thermal stability. The calculated detonation properties indicate that incorporating the -NO2, -NF2, -ONO2, or -N(NO2)2 group into the TETZ or TTZ ring is very helpful for enhancing its detonation performance. Considered the detonation performance and thermal stability, four derivatives may be regarded as the promising candidates of high-energy density materials (HEDMs). © 2010 Elsevier B.V.


He M.,Nanjing University of Science and Technology | Fries R.J.,Texas A&M University | Rapp R.,Texas A&M University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

Employing nonperturbative transport coefficients for heavy-flavor (HF) diffusion through quark-gluon plasma (QGP), hadronization and hadronic matter, we compute D- and B-meson observables in Pb+Pb (s=2.76TeV) collisions at the LHC. Elastic heavy-quark scattering in the QGP is evaluated within a thermodynamic T-matrix approach, generating resonances close to the critical temperature which are utilized for recombination into D and B mesons, followed by hadronic diffusion using effective hadronic scattering amplitudes. The transport coefficients are implemented via Fokker-Planck Langevin dynamics within hydrodynamic simulations of the bulk medium in nuclear collisions. The hydro expansion is quantitatively constrained by transverse-momentum spectra and elliptic flow of light hadrons. Our approach thus incorporates the paradigm of a strongly coupled medium in both bulk and HF dynamics throughout the thermal evolution of the system. At low and intermediate p T, HF observables at LHC are reasonably well accounted for, while discrepancies at high p T are indicative for radiative mechanisms not included in our approach. © 2014 The Authors.


Shi L.,Huaihai Institute of Technology | Li X.,Nanjing University of Science and Technology
Journal of Luminescence | Year: 2011

ZnO/SiO2 thin films were fabricated on Si substrates by E-beam evaporation with thermal retardation. The as-prepared films were annealed for 2 h every 100 °C in the temperature range 400800 °C under ambient air. The structural and optical properties were investigated by X-ray diffraction (XRD), atomic force microscopy (AFM) and photoluminescence (PL). The XRD analysis indicated that all ZnO thin films had a highly preferred orientation with the c-axis perpendicular to the substrate. From AFM images (AFM scan size is 1 μm×1 μm), the RMS roughnesses of the films were 3.82, 5.18, 3.65, 3.40 and 13.2 nm, respectively. PL measurements indicated that UV luminescence at only 374 nm was observed for all samples. The optical quality of the ZnO film was increased by thermal retardation and by using an amorphous SiO2 buffer layer. © 2010 Elsevier B.V. All rights reserved.


Ma L.,Nanjing University of Science and Technology | Wang Z.,Brunel University | Bo Y.,Nanjing University of Science and Technology | Guo Z.,Nanjing University of Science and Technology
Systems and Control Letters | Year: 2011

This paper is concerned with the mixed ℋ2/ ℋH∞ control problem for a class of stochastic time-varying systems with nonlinearities. The nonlinearities are described by statistical means and could cover several kinds of well-studied nonlinearities as special cases. The occurrence of the addressed nonlinearities is governed by two sequences of Bernoulli distributed white sequences with known probabilities. Such nonlinearities are named as randomly occurring nonlinearities (RONs) as they appear in a probabilistic way. The purpose of the problem under investigation is to design a controller such that the closed-loop system achieves the expected ℋ2 performance requirements with a guaranteed ℋH∞ disturbance attenuation level. A sufficient condition is given for the existence of the desired controller by means of solvability of certain coupled matrix equations. By resorting to the game theory approach, an algorithm is developed to obtain the controller gain at each sampling instant. A numerical example is presented to show the effectiveness and applicability of the proposed method. © 2011 Elsevier B.V. All rights reserved.


Ma L.,Nanjing University of Science and Technology | Wang Z.,Brunel University | Bo Y.,Nanjing University of Science and Technology | Guo Z.,Nanjing University of Science and Technology
International Journal of Robust and Nonlinear Control | Year: 2012

In this paper, an H ∞ sliding mode control (SMC) problem is studied for a class of discrete-time nonlinear stochastic systems with multiple data packet losses. The phenomenon of data packet losses, which is assumed to occur in a random way, is taken into consideration in the process of data transmission through both the state-feedback loop and the measurement output. The probability for the data packet loss for each individual state variable is governed by a corresponding individual random variable satisfying a certain probabilistic distribution over the interval [0 1]. The discrete-time system considered is also subject to norm-bounded parameter uncertainties and external nonlinear disturbances, which enter the system state equation in both matched and unmatched ways. A novel stochastic discrete-time switching function is proposed to facilitate the sliding mode controller design. Sufficient conditions are derived by means of the linear matrix inequality (LMI) approach. It is shown that the system dynamics in the specified sliding surface is exponentially stable in the mean square with a prescribed H ∞ noise attenuation level if an LMI with an equality constraint is feasible. A discrete-time SMC controller is designed capable of guaranteeing the discrete-time sliding mode reaching condition of the specified sliding surface with probability 1. Finally, a simulation example is given to show the effectiveness of the proposed method. © 2011 John Wiley & Sons, Ltd.


Xu S.,Nanjing University of Science and Technology | Feng G.,Nanjing University of Science and Technology | Feng G.,City University of Hong Kong | Zou Y.,Nanjing University of Science and Technology | And 2 more authors.
IEEE Transactions on Automatic Control | Year: 2012

This technical note deals with the problem of robust controller design of uncertain discrete time-delay systems subject to control input saturation and bounded external disturbances. A sufficient condition is obtained, which guarantees the existence of state feedback controllers and an admissible initial condition domain such that the resulting closed-loop system is uniformly exponentially convergent to a ball with certain exponential decay rate for every initial condition emanating from the admissible domain. An iterative linear matrix inequality relaxation scheme can be used to construct desired state feedback controllers. A simulation example is provided to demonstrate the effectiveness of the proposed method. © 1963-2012 IEEE.


Tao W.,Nanjing University of Science and Technology | Liu T.,Kochi University of Technology | Zheng R.,University of Tokyo | Feng H.,Nanjing University of Science and Technology
Sensors | Year: 2012

Gait analysis using wearable sensors is an inexpensive, convenient, and efficient manner of providing useful information for multiple health-related applications. As a clinical tool applied in the rehabilitation and diagnosis of medical conditions and sport activities, gait analysis using wearable sensors shows great prospects. The current paper reviews available wearable sensors and ambulatory gait analysis methods based on the various wearable sensors. After an introduction of the gait phases, the principles and features of wearable sensors used in gait analysis are provided. The gait analysis methods based on wearable sensors is divided into gait kinematics, gait kinetics, and electromyography. Studies on the current methods are reviewed, and applications in sports, rehabilitation, and clinical diagnosis are summarized separately. With the development of sensor technology and the analysis method, gait analysis using wearable sensors is expected to play an increasingly important role in clinical applications. © 2012 by the authors.


Xin Y.,Nanjing University of Science and Technology | He Y.,Guangdong University of Petrochemical Technology | Chen Y.,Nanjing University of Science and Technology | Li J.,Nanjing University of Science and Technology
Optics Letters | Year: 2010

The correlation between intensity fluctuations of light scattered from a quasi-homogeneous random media was analytically derived. We showed the correlation depends on spatial Fourier transforms of both the intensity and degree of spatial correlation of scattering potentials of the media, while the normalized correlation equals the squared modulus of the degree of spatial coherence of the scattered fields. © 2010 Optical Society of America.


He M.,Nanjing University of Science and Technology | Fries R.J.,Texas A&M University | Rapp R.,Texas A&M University
Physical Review C - Nuclear Physics | Year: 2015

We calculate open heavy-flavor (HF) production in Au+Au collisions at sNN=62.4 GeV utilizing a nonperturbative transport approach as previously applied in nuclear collisions at top Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies. The effects of hot QCD matter are treated in a strong-coupling framework, by implementing heavy-quark diffusion, hadronization, and heavy-flavor meson diffusion within a hydrodynamic background evolution. Since in our approach the heavy-flavor coupling to the medium is strongest in the pseudocritical region (including the effects of resonance recombination), it is of interest to test its consequences at lower collision energies where the sensitivity to this region should be enhanced relative to the initially hotter fireball temperatures reached at top RHIC and LHC energies. We find that the suppression and flow pattern of the nonphotonic electrons from heavy-flavor decays at 62.4 GeV emerges from an intricate interplay of thermalization and initial-state effects, in particular a Cronin enhancement which is known to become more pronounced toward lower collision energies. © 2015 American Physical Society.


Rapp R.,Texas A&M University | van Hees H.,FIAS | van Hees H.,Institute for Theoretical Physics | He M.,Nanjing University of Science and Technology
Nuclear Physics A | Year: 2014

We study the emission characteristics of thermal photons at RHIC and LHC as affected by both the space-time evolution of the bulk medium and the thermal emission rates. For the former we compare the results of two evolution models (expanding fireball and hydrodynamics). For the latter, we detail the influence of hadronic emission components and study a speculative scenario by upscaling the default QGP and hadronic rates around the pseudo-critical region. © 2014 Elsevier B.V.


Li L.,Nanjing University of Science and Technology | Zhong Q.,Delta Electronics Inc
IEEE Transactions on Industrial Electronics | Year: 2012

In this paper, a novel Zeta-mode three-level ac direct converter is proposed. The converter realizes three-level voltage waveforms before the output filter, which can get a better harmonic spectrum and reduce the bulk of the filter. Compared with two-level ac choppers, voltage stresses of the converter can be lowered. Compared with ac-dc-ac converters with no isolation and low- or middle-frequency isolation, the converter has single power stage and bidirectional power flow. Moreover, compared with buck-mode three-level ac choppers, it can realize buck and boost output voltage. The converter has four operation states in one period of input voltage and three different operation modes in one switching period. To ensure that the converter operates reliably, the noncomplementary control strategy is presented, which can make the converter switch smoothly between different modes in bidirectional power flow. Therefore, the converter is suitable to different kinds of loads. Principle analysis and experiment results of the prototype well verify the advantages of the proposed converter. © 2011 IEEE.


Zhang Z.,Qufu Normal University | Zhang Z.,Key Laboratory of System Control and Information Processing | Xu S.,Nanjing University of Science and Technology | Zhang B.,Nanjing University of Science and Technology
IEEE Transactions on Automatic Control | Year: 2014

This technical note is concerned with the problem of adaptive tracking control for a class of nonlinear systems with parametric uncertainty, unknown actuator nonlinearity and bounded external disturbance. Two type of actuator nonlinearities, that is, symmetric dead-zone and Bouc-Wen hysteresis, are considered, respectively. First, an adaptive control scheme with positive integrable time-varying function is presented to compensate for the dead-zone nonlinearity. Then, the actuator nonlinearity under consideration is modeled as Bouc-Wen hysteresis, and desired compensation controller is designed based on the backstepping technique and Nussbaum gain approach. In both of the two schemes, the asymptotic tracking is guaranteed with the tracking error converging to zero. Finally, an illustrative example is provided to show the effectiveness of the proposed design methods. © 1963-2012 IEEE.


Xiang H.J.,Fudan University | Xiang H.J.,National Renewable Energy Laboratory | Huang B.,National Renewable Energy Laboratory | Kan E.,Nanjing University of Science and Technology | And 2 more authors.
Physical Review Letters | Year: 2013

Diamond silicon (Si) is the leading material in the current solar cell market. However, diamond Si is an indirect band gap semiconductor with a large energy difference (2.3 eV) between the direct gap and the indirect gap, which makes it an inefficient absorber of light. In this work, we develop a novel inverse band structure design approach based on the particle swarming optimization algorithm to predict the metastable Si phases with better optical properties than diamond Si. Using our new method, we predict a cubic Si 20 phase with quasidirect gaps of 1.55 eV, which is a promising candidate for making thin-film solar cells. © 2013 American Physical Society.


Tan H.,Nanjing University of Science and Technology | Gao X.,Nanjing University of Science and Technology | Sun J.,Nanjing University of Science and Technology | Xiao C.,Nanjing University of Science and Technology | Hu X.,Jinling Institute of Technology
Chemical Communications | Year: 2013

A double stimulus-sensing platform based on a biopolymer hydrogel was developed for inducing stem cell aggregation and subsequent release. Our work will bring up a novel methodology to generate smart scaffolds with tailorable properties for biomedical applications. © 2013 The Royal Society of Chemistry.


Chen Y.,CAS Dalian Institute of Chemical Physics | Chen Y.,Nanjing University of Science and Technology | Wang F.,CAS Dalian Institute of Chemical Physics | Zhen W.,CAS Dalian Institute of Chemical Physics | Li X.,CAS Dalian Institute of Chemical Physics
Advanced Synthesis and Catalysis | Year: 2013

The rhodium(III)-catalyzed coupling of azomethine ylides with alkynes via C-H activation has been developed for the synthesis of indenamines in moderate to high yields. The coupled products can be further oxidized to indenones and derivatives. © 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.


Xiang H.J.,Fudan University | Kan E.J.,Nanjing University of Science and Technology | Wei S.-H.,National Renewable Energy Laboratory | Whangbo M.-H.,North Carolina State University | Gong X.G.,Fudan University
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

A novel general method of describing the spin-lattice interactions in magnetic solids is proposed in terms of first-principles calculations. The spin exchange and Dzyaloshinskii-Moriya interactions, as well as their derivatives with respect to atomic displacements, can be evaluated efficiently on the basis of density-functional calculations for four ordered spin states. By taking into consideration the spin-spin interactions, the phonons, and the coupling between them, we show that the ground-state structure of a representative spin-frustrated spinel, MgCr 2O 4, is tetragonally distorted, in agreement with experiments. However, our calculations find the lowest energy for the collinear spin ground state, in contrast to previously suggested noncollinear models. © 2011 American Physical Society.


Kan E.,Nanjing University of Science and Technology | Li M.,Nanjing University of Science and Technology | Hu S.,Uppsala University | Xiao C.,Nanjing University of Science and Technology | And 2 more authors.
Journal of Physical Chemistry Letters | Year: 2013

Two-dimensional materials have been the hot subject of studies due to their great potential in applications. However, their applications in spintronics have been blocked by the difficulty in producing ordered spin structures in 2D structures. Here we demonstrated that the ultrathin films of recently experimentally realized wurtzite MnO can automatically transform into a stable graphitic structure with ordered spin arrangement via density functional calculation, and the stability of graphitic structure can be enhanced by external strain. Moreover, the antiferromagnetic ordering of graphitic MnO single layer can be switched into half-metallic ferromagnetism by small hole-doping, and the estimated Curie temperature is higher than 300 K. Thus, our results highlight a promising way toward 2D magnetic materials. © 2013 American Chemical Society.


Chen F.,Nanjing University of Science and Technology | Hu W.,Jiangsu Academy of Environmental Sciences | Zhong Q.,Nanjing University of Science and Technology
Atmospheric Research | Year: 2013

Real-world vehicle emission factors for PM10 (particulate matter with aerodynamic diameter smaller than 10μm) and particle-phase polycyclic aromatic hydrocarbons (PAHs) from mixed vehicles were quantified in the Fu Gui-shan Tunnel of Nanjing during summer and winter of 2010. Concentrations of PM10 and sixteen particle phase polycyclic aromatic hydrocarbons (PAHs) in the entrance and exit of the tunnel were studied. The results showed that the four most abundant particular phase polycyclic aromatic hydrocarbons (PAHs) of motor vehicle were benzo[ghi]perylene, benzo[k]fluoranthene, benz[a]anthracene and benzo[a]pyrene. The emission factors for PM10 and particle-phase PAHs were 687mgveh-1km-1 and 18.853mgveh-1km-1 in summer, 714mgveh-1km-1 and 20.374mgveh-1km-1 in winter. Higher particle-phase PAH emission factors were found to be associated with a high proportion of diesel-fueled vehicles (DV). The estimated PM10 emission factor of gasoline-fueled vehicles (GV) was 513mgveh-1km-1 and the value for DV was 914mgveh-1km-1, while EFDV of particulate PAH (31.290mgveh-1km-1) was nearly 4 times higher than EFGV (9.310mgveh-1km-1). The five highest emission factors of diesel-fueled vehicles (DV) were benzo[ghi]perylene, benzo[k]fluoranthene, Indeno[1,2,3-cd]pyrene, benz[a]anthracene and benzo[a]pyrene, which was similarly found in the gasoline-fueled vehicles (GV). The sum of these five emission factors accounted for ~69% of the total particle-phase PAH of DV and ~67% of GV. © 2013 Elsevier B.V.


Tan H.,Nanjing University of Science and Technology | Xiao C.,Nanjing University of Science and Technology | Sun J.,Nanjing University of Science and Technology | Xiong D.,Nanjing University of Science and Technology | Hu X.,Jinling Institute of Technology
Chemical Communications | Year: 2012

A biological hydrogel was self-assembled via Watson-Crick base pairing of thymine and adenine from functionalized star poly(ethylene glycol). Our work should provide a novel methodology to generate robust injectable scaffolds with tailorable properties for biomedical applications. © 2012 The Royal Society of Chemistry.


Xiong R.,PLA University of Science and Technology | Chen B.,PLA University of Science and Technology | Fang D.,Nanjing University of Science and Technology
IEEE Transactions on Antennas and Propagation | Year: 2014

A sub-cell algorithm for the finite-difference time-domain (FDTD) modeling of flat electrode in grounding systems is proposed. The electromagnetic field variation near a flat electrode is derived from the integral of the differential electric field which is radiated by the distributed charge on an electrostatic charged flat electrode. By fully incasing the field singularity into the coarse cells containing the electrode with the Faraday's Law, a sub-cell algorithm has been proposed to reduce computational resources when modeling the flat electrode. The accuracy of the derived field singularity is verified from comparison with the field given by the high-resolution standard FDTD simulation. The efficiency of the proposed algorithm has been approved by verifying the transient grounding resistance (TGR) of the grounding system using the proposed algorithm and the computational memory and time usage. © 2013 IEEE.


Xiang H.J.,Fudan University | Kan E.J.,Nanjing University of Science and Technology | Zhang Y.,North Carolina State University | Whangbo M.-H.,North Carolina State University | Gong X.G.,Fudan University
Physical Review Letters | Year: 2011

The ferroelectric polarization of triangular-lattice antiferromagnets induced by helical spin-spiral order is not explained by any existing model of magnetic-order-driven ferroelectricity. We resolve this problem by developing a general theory for the ferroelectric polarization induced by spin-spiral order and then by evaluating the coefficients needed to specify the general theory on the basis of density functional calculations. Our theory correctly describes the ferroelectricity of triangular-lattice antiferromagnets driven by helical spin-spiral order and incorporates known models of magnetic-order-driven ferroelectricity as special cases. © 2011 American Physical Society.


Tan H.,Nanjing University of Science and Technology | Hu X.,Jinling Institute of Technology
Journal of Applied Polymer Science | Year: 2012

An injectable and glucose-responsive hydrogel derived from dextran derivatives and lectin concanavalin A (ConA) was synthesized to deliver adipogenic factor for adipose tissue engineering. The gelation is attributed to the Schiff-base reaction cross-linking between aldehydic and aminated dextran. To enhance adipogenesis, the adipogenic factor of insulin was incorporated in the ConA immobilized hydrogels. The gelation time, compressive modulus, morphologies, weight loss, and swelling properties of the hydrogels were investigated. The ConA triggered a competitive displacement of dextran by glucose from the lectin receptor sites, and results in increasing swelling of the gel network. The swelling ratio (SR) of ConA immobilized hydrogel showed glucose dependent properties and linearly increased from 19.8 to 31.3 at 37°C in PBS at glucose concentrations between 0 and 1.0% (w/v). The in vitro release experiments showed that the insulin would be released from this dextran hydrogel into the local microenvironment in response to glucose, thus highlighting the potential of such a injectable and biodegradable hydrogel to be used as part of implantable scaffold to delivery adipogenic factor for adipose tissue engineering. © 2012 Wiley Periodicals, Inc.


An Q.,Beijing Jiaotong University | Zhang F.,Beijing Jiaotong University | Li L.,Beijing Jiaotong University | Wang J.,Beijing Jiaotong University | And 3 more authors.
ACS Applied Materials and Interfaces | Year: 2014

We present performance improved ternary bulk heterojunction polymer solar cells by doping a small molecule, 2,4-bis[4-(N,N-diisobutylamino)-2,6- dihydroxyphenyl] squaraine (DIB-SQ), into the common binary blend of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). The optimized power conversion efficiency (PCE) of P3HT:PC71BM-based cells was improved from 3.05% to 3.72% by doping 1.2 wt % DIB-SQ as the second electron donor, which corresponds to ∼22% PCE enhancement. The main contributions of doping DIB-SQ material on the improved performance of PSCs can be summarized as (i) harvesting more photons in the low-energy range, (ii) increased exciton dissociation, energy transfer, and charge carrier transport in the ternary blend films. The energy transfer process from P3HT to DIB-SQ is demonstrated by time-resolved transient photoluminescence spectra through monitoring the lifetime of 700 nm emission from neat P3HT, DIB-SQ and blended P3HT:DIB-SQ solutions. The lifetime of 700 nm emission is increased from 0.9 ns for neat P3HT solution, to 4.9 ns for neat DIB-SQ solution, to 6.2 ns for P3HT:DIB-SQ blend solution. © 2014 American Chemical Society.


Chen Y.,CAS Dalian Institute of Chemical Physics | Chen Y.,Nanjing University of Science and Technology | Wang F.,CAS Dalian Institute of Chemical Physics | Jia A.,Nanjing University of Science and Technology | Li X.,CAS Dalian Institute of Chemical Physics
Chemical Science | Year: 2012

Substrate-controlled selective oxidative olefination of N-protected 2-pyridones has been achieved under palladium catalysis. The 5-position selectivity was followed for N-protected simple pyridones. Introduction of substituents into the 4- or the 6-position switched the site selectivity to the 3-position. Diolefination can also be achieved with high efficiency. Oxidative arylation with polyfluorobenzenes followed a similar selectivity except that the system is more sterically and electronically demanding. © 2012 The Royal Society of Chemistry.


Xiang Z.,Nanjing University of Science and Technology | Wang R.,PLA University of Science and Technology
International Journal of Modelling, Identification and Control | Year: 2011

This paper investigates the observer design for non-linear switched systems with time delay under asynchronous switching. Firstly, when the switching instants between the observer and the system are asynchronous, the state observer for switched linear systems with time delay is developed; the proposed observer can guarantee exponentially convergence of the estimated state error. Then, the proposed approach is extended to design observer for switched systems with time delay and Lipschitz non-linearities under asynchronous switching. Furthermore, the problem of non-fragile observer design for switched non-linear systems with time delay under asynchronous switching is investigated. Finally, a numerical example is given to illustrate the effectiveness of the proposed method. Copyright © 2011 Inderscience Enterprises Ltd.


Zhang X.,Nanjing University | Zhang X.,CAS Dalian Institute of Chemical Physics | Chen D.,CAS Dalian Institute of Chemical Physics | Chen D.,Nanjing University of Science and Technology | And 4 more authors.
Advanced Synthesis and Catalysis | Year: 2011

Isoquinolines have been synthesized from the redox-neutral dehydrative C-N and C-C cross-coupling between oximines and alkynes using a catalytic amount of (pentamethylcyclopentadiene)rhodium dichloride dimer {[RhCp*Cl 2]2} and cesium acetate (CsOAc), a process that involves ortho C-H activation of oximines and subsequent functionalization with alkynes. This redox-neutral catalytic isoquinoline synthesis operates under mild conditions, and is insensitive to moisture or air. A broad scope of coupling partners has been established, and a likely mechanism has been suggested. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Xiang Z.,Nanjing University of Science and Technology | Wang R.,PLA University of Science and Technology
Transactions of the Institute of Measurement and Control | Year: 2010

This paper considers the problem of stability and robust H ∞ stabilization for a class of uncertain switched systems using the delta operator. Based on multiple Lyapunov function method, a sufficient condition for the existence of stability of the delta operator switched system is presented, and the design approach to robust H∞ state feedback controller is addressed. The proposed controller can robustly stabilize the uncertain delta operator switched system, and also guarantee H ∞ performance of the closed-loop system for all admissible parameter perturbations. The solution to the controller is formulated in the form of a set of linear matrix inequalities. A numerical example is provided to illustrate the effectiveness of the developed method. © 2010 The Institute of Measurement and Control.


Dai J.,Jiangsu University | Xu X.,Nanjing University of Science and Technology | Zhao D.,Jiangsu University
IEEE Antennas and Wireless Propagation Letters | Year: 2013

Sparse representation direction-of-arrival (DOA) estimation methods exhibit many advantages over other DOA estimation methods. However, they suffer from a high computational complexity. This letter describes a real-valued sparse representation method through utilizing a unitary transformation that can convert complex-valued manifold matrices of uniform linear arrays (ULAs) into real ones. Due to this transformation, the computational complexity is decreased by a factor of at least four. The letter also shows that the proposed method has a better noise suppression because of exploiting an additional real structure. Therefore, it outperforms the original method, especially when signal-to-noise ratio (SNR) is low. Simulation results verify the performance improvement of the proposed method. © 2002-2011 IEEE.


Cui L.,Nanjing University of Science and Technology | Wu W.,Nanjing University of Science and Technology | Fang D.-G.,Nanjing University of Science and Technology
IEEE Antennas and Wireless Propagation Letters | Year: 2013

A frequency beam-scanning antenna with backfire-to-endfire beam-steering capability is proposed and investigated. This antenna is with printed planar structure that consists of a low-loss slow-wave printed meander line based on the even-mode bilateral broadside-coupled suspended microstrip line (BSML). The propagation properties of the meander-line unit and its principles for frequency-scanning applications are studied extensively. This printed antenna achieves the measured beam scanning of-27.5° to 46° with the frequency sensitivity of 43.24°/GHz and a maximum gain of 15.5 dBi. The antenna exhibits flat gain of more than 13 dBi in the whole frequency range from 8.9 to 10.6 GHz. The sidelobe levels are near 20 dB. The design flexibility of this kind of antenna is shown. © 2002-2011 IEEE.


Huang H.,Nanjing University of Science and Technology | Wang X.,Nanjing University of Science and Technology
Nanoscale | Year: 2011

Graphene nanoplate-MnO2 composites have been synthesized by oxidising part of the carbon atoms in the framework of graphene nanoplates at ambient temperature. The composites were characterized by means of X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV). It was found that the oxidation extent of the carbon atoms in the graphene framework in these composites was dependent on the reaction time, which also influenced their microstructure, morphology and electrochemical properties. Compared with MnO2 nanolamellas, the nanocomposite prepared with a reaction time of 3 h reveals better electrochemical properties as a supercapacitor electrode material. © 2011 The Royal Society of Chemistry.


Shen Y.,Nanjing University of Science and Technology
Archive of Applied Mechanics | Year: 2015

Painlevé paradox is a well-known problem in non-smooth dynamics. Till now, all relevant researches only focus on the Painlevé paradox of a rigid rod sliding on a rough surface with large coefficient of friction $$\mu $$μ. However, if the compliance of the whole rod is considered, the Painlevé paradox problem will transform into a ‘bouncing phenomenon’ caused by jam (self-locking), which has not been studied. The aim of this paper was to analyze the relationship between the Painlevé paradox of the rigid rod and the dynamic jam behavior of the elastic rod. The full transient method is used to calculate the dynamic response of elastic rod. In comparison with the rigid rod, the compliance of the whole rod will bring a different critical value of coefficient of friction $$\mu _\mathrm{c}$$μc. The stress waves are excited by the abrupt change of the contact forces, and they propagate in the rod. A ‘quasi-stick’ state of the contact surface is found, which supports the feasibility of the single-point compliant contact model. In addition, the peak value of normal contact force $$F_{3}$$F3 and normal contact impulse $$P_{3}$$P3 is constant when the system parameters $$(\theta , \mu )$$(θ,μ) are located in the region of Painlevé paradox. © 2015, Springer-Verlag Berlin Heidelberg.


Fan Y.,Anhui University | Liu L.,City University of Hong Kong | Feng G.,City University of Hong Kong | Song C.,Nanjing University of Science and Technology | Wang Y.,Hefei University of Technology
Automatica | Year: 2013

In this work the connectivity preserving problem of multiple agents with limited communication ranges in the context of rendezvous tasks has been investigated. The communication among agents is considered to be unreliable and the control inputs of agents are required to be bounded. Based on the explicitly defined virtual neighbors, the proximity graph connectivity of the agent group has been preserved. Moreover, by using the constraint function approach, the control inputs are guaranteed to be bounded, which can be easily implemented in practice. It is proved that the proposed control law can not only ensure union connectivity of the underlying communication graph, but also drive the agents to rendezvous. The effectiveness of the control law is illustrated by numerical examples. © 2013 Elsevier Ltd. All rights reserved.


Yang W.,Nanjing University of Science and Technology | Wang H.,Nanjing University of Science and Technology | Che W.,Nanjing University of Science and Technology | Wang J.,Nanjing University of Science and Technology
IEEE Antennas and Wireless Propagation Letters | Year: 2013

In this letter, a new edge-fed patch antenna element using artificial magnetic conductor structures (AMCs) is proposed. The AMCs are employed as the antenna magnetic ground plane for bandwidth enhancement and radiation gain improvement of patch antenna. Meanwhile, the ground plane below the feedline is raised, the height of substrate is reduced, so the feedline width would be narrow to avoid the spurious radiation. In addition, it has been particularly found that the height and number of the AMCs have a specific impact on performances of antenna with AMCs. On the basis of antenna element design, a 2×2 array with AMC techniques is also proposed. Compared to the dual-thickness-substrate antenna and cavity-backed antenna in the previous literature, the antenna element and array with the AMCs have wider bandwidth and higher-gain performances. The simulated and measured results both demonstrate significant improvements. The antenna element exhibits 11.76% bandwidth and high gain of 9.36 dBi; the 2×2 array achieves 20.45% impedance bandwidth and high gain of 15.95 dBi. © 2002-2011 IEEE.


Zhang C.,Nanjing University of Science and Technology
Kongzhi Lilun Yu Yingyong/Control Theory and Applications | Year: 2013

Many approaches for trajectory tracking of nonholonomic mobile robots have been proposed. Most of them are designed based on the control of robot dynamics or adopt the complicated kinematics control, which are not suitable for real-time engineering applications without powerful computing devices. A real-time tracking controller based on PD controller is presented for nonholonomic mobile robot. This algorithm holds a time cost of only 1~2 ms for each control loop in a 40 MHz embedded controller. A nonlinear-PID based velocity controller for DC driving motors is integrated with the proposed tracking controller to fulfill the path tracking control of a wheeled mobile robot (WMR). To estimate the yaw angle of WMR, a low-cost micro electro-mechanical system (MEMS) measurement unit is employed in the experimental setup. The experimental results show the effectiveness of the proposed method.


Zhang Y.,Nanjing University of Science and Technology | Gu D.-W.,University of Leicester | Xu S.,Nanjing University of Science and Technology
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2013

This paper is on the design problem of global exponential adaptive synchronization for a class of stochastic complex dynamical networks. In the considered networks, the dynamics of each node are approximated by a neutral-type neural network. The stochastic disturbances are described in terms of Brownian motions. Different from the prior references, the coefficient matrix of the adaptive controller under consideration is an arbitrary matrix instead of an identity one. By using Lyapunov method and some properties of Kronecker product, a sufficient condition is proposed to ensure the dynamics of the considered network globally exponentially synchronize with the desired solution in the mean square sense. Some criteria for global exponential adaptive synchronization of complex dynamical networks with general nodes are further provided in forms of corollaries. In particular, the proposed criteria for network synchronization are in terms of linear matrix inequalities. Only two variables are used in each criterion and the variables are not inside of any Kronecker product. Hence, the conditions are easy to check. A numerical example is presented to show the effectiveness and applicability of the proposed approach. © 2013 IEEE.


Zhang B.,Nanjing University of Science and Technology | Zheng W.X.,University of Western Sydney | Xu S.,Nanjing University of Science and Technology
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2013

This paper is concerned with the design of mode-dependent and mode-independent filters for continuous-time linear Markovian jump systems (MJSs) with time-varying delays. Different from the existing studies in the literature, the purpose of this paper is to solve the H∞, L2-L∞, passive and dissipative filtering problems in a unified framework. This purpose is successfully realized by using a new performance index that is referred to as extended dissipativity. The extended dissipative inequality contains several weighting matrices. By tuning the weighting matrices, the extended dissipativity will reduce to the H ∞ performance, L2-L∞ performance, passivity and dissipativity, respectively. Delay-dependent conditions for the analysis of stochastic stability and extended dissipativity for MJSs with time-varying delays are obtained by using a mode-dependent Lyapunov-Krasovskii functional together with a novel integral inequality. Based on these conditions, the design methods for mode-dependent and mode-independent filters are developed based on linear matrix inequalities. The designed filters guarantee that the resulting filtering error system is stochastically stable and extended dissipative for any admissible delays. Finally, the effectiveness of the proposed methods is substantiated with three illustrative examples. © 2004-2012 IEEE.


Zhang Y.,Nanjing University of Science and Technology | Zhang Y.,Central Queensland University | Han Q.-L.,Central Queensland University
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2013

This paper focuses on network-based master-slave synchronization for delayed neural networks through a remote controller. The insertion of communication networks in a master-slave synchronization scheme inevitably induces network delays, packet dropouts and stochastic fluctuations. The data packets may be received with a different temporal order from that they are sent due to the fact that the network-induced delay is time-varying. A logic data processor and a logic zero order hold are proposed in the master-slave synchronization framework. Then an error system for the master system and the slave system is formulated. By combining a generalized Jensen integral inequality and a convex combination technique, some synchronization criteria are derived to ensure the mean-square global exponential synchronization of state trajectories for the master system and the slave system. The controller gain matrix is obtained by solving a minimization problem in terms of linear matrix inequalities using a cone complementary technique. As a special case in which only network-induced delays and packet dropouts are occurred in the signal transmission channels, some results are also presented. Finally, two illustrative examples are provided to show the effectiveness and applicability of the proposed scheme. © 2004-2012 IEEE.


Zhang X.B.,Nanjing University of Science and Technology
Journal of Engineering and Applied Science | Year: 2013

In this work the interior ballistic design for 76 mm naval medium caliber gun with guided projectile is discussed using a mixture propellant of granular sevenperforated propellant and tubular propellant. The guided projectile needs some requirements such as high muzzle velocity, low maximum pressure and projectile acceleration lower than 10000 g "g is the gravitational acceleration", The numerical approach for interior ballistic cycle simulation is carried out by using lumped-parameter model with a mixture propellant, the lumped-parameter model is widely used for the prediction of interior ballistic parameters such as peak pressure and muzzle velocity. Some of the design parameters are changed such as the charge mass and the web thickness for each propellant, the effect of these changes on the interior ballistic performance is analyzed to obtain the tactical requirements and safety firing for the guided projectile.


Simultaneous reconstruction of temperature field and radiative properties including scattering albedo and extinction coefficient is presented in a 2-D rectangular, absorbing, emitting, and isotropically scattering gray medium from the knowledge of the exit radiative intensities received by charge-coupled device cameras at boundary surfaces. The inverse problem is formulated as a non-linear optimization problem and solved by stochastic particle swarm optimization. The effects of particle swarm size, generation number, measurement errors, and optical thickness on the accuracy of the estimation, and computing time were investigated and the results show that the temperature field and radiative properties can be reconstructed well for the exact and noisy data, but radiative properties are harder to obtain than temperature field. Moreover, the extinction coefficient is more difficult to reconstruct than scattering albedo.


Sha Q.,Nanjing University of Science and Technology | Wei Y.,Nanjing University of Science and Technology
Synthesis (Germany) | Year: 2013

A simple, highly efficient, one-pot synthesis of 3,5-di-aryl-4- bromopyrazoles via 1,3-dipolar cycloaddition of diazo compounds and alkynyl bromides has been developed. The diazo compounds and alkynyl bromides were generated in situ from tosylhydrazones and gem-dibromoalkenes, respectively. When ketone-derived hydrazones were used, 3,5-diaryl-4-bromo-3H-pyrazoles were obtained and the isomerization products 3,5-diaryl-4-bromo-1H-pyrazoles were formed when using aldehyde-derived hydrazones. The reaction system exhibited high regioselectivity and good functional group tolerance. Both electron-rich and electron-deficient-substituents on the aromatic ring of the hydrazones or the gem-dibromoalkenes gave desired products in moderate to good yields (67-86%). © Georg Thieme Verlag Stuttgart - New York.


Zhang M.,Nanjing University of Science and Technology | Ma Y.,Nanjing University of Science and Technology | Zhu Y.,Nanjing Normal University | Che J.,Nanjing University of Science and Technology | Xiao Y.,Nanjing Normal University
Carbon | Year: 2013

Transparent hydrophobic coatings were prepared with graphene fluoride (GF), which was fabricated by a mild and controllable approach of liquid-phase ultrasonic exfoliation of graphite fluoride (GiF) with a selected solvent of ethanol. The structure of the resulting GF sheets with nanoscale thickness was confirmed by transmission electron microscope (TEM), atomic force microscopy (AFM), X-ray diffraction and Raman spectroscopy. Fourier transform infrared spectroscopy and energy dispersive analysis show that C-F bonds from GiF are well preserved in the resulting GF by the method of liquid-phase ultrasonic exfoliation, which are responsible for its excellent hydrophobicity and light transmission. The obtained GF coating has a contact angle of 123 and light transmittance of up to 92% when GF mass density is 0.6 μg cm-2. Water erosion experiments and ultraviolet aging tests suggest these coatings may possess extended service life outdoors. © 2013 Elsevier Ltd. All rights reserved.


Kong X.,Nanjing University of Science and Technology | Ding X.,Nanjing University of Science and Technology
International Journal of Hydrogen Energy | Year: 2011

A novel layered perovskite SmBaCu2O5+δ (SBCO) as a potential cathode for intermediate temperature solid oxide fuel cells (IT-SOFC) has been investigated in this paper. The SmBaCu2O 5+δ oxide was synthesized by EDTA- Citrate complexing sol-gel process. The crystal structure, the thermal expansion, the electrical conductivity and electrochemical properties have been characterized by X-ray diffraction (XRD), dilatometer, four-probe dc method, electrochemical impedance spectroscopy (EIS) and cathodic polarization examinations. The average thermal expansion coefficient (TEC) of SBCO was 14.6 × 10-6/ °C in the temperature range of 50-800 °C, which matched Sm-doped ceria (SDC) electrolytes. The electrode polarization resistance was 0.469 Ωcm 2. Considering low thermal expansions and good electrochemical properties, layered perovskite SBCO shows promising performance as cathode material for IT-SOFCs. © 2011 Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.


Liu Y.,Nanjing University of Science and Technology | Gong X.,Nanjing University of Science and Technology | Wang L.,Nanjing University of Science and Technology | Wang G.,Nanjing University of Science and Technology
Journal of Physical Chemistry C | Year: 2011

The effect of hydrostatic pressure on the geometrical, electronic, and thermodynamic properties of the energetic material 2-diazo-4,6-dinitrophenol (DDNP) has been investigated by density functional theory periodic calculations. The crystal structure optimized by the local density approximation with the Ceperley-Alder exchange-correlation potential parametrized by Perdew and Zunger compares well with the experimental results at the ambient pressure. When the hydrostatic compression is exerted upon the DDNP crystal, the interatomic distances, bond angles, and dihedral angles of DDNP molecule change regularly with the increase in pressure except at 10, 59, and 66 GPa where the structural transformations occur. The same is true for the unit cell lattice parameters, density, total energy, band gap, density of states, and thermodynamic functions. When the pressure is below 10 GPa, DDNP molecule exists in the quinoid form (I). As the pressure is between 10 and 58 GPa, it has the cyclic azoxy form (II). In the range of 0-58 GPa, DDNP crystal is anisotropic. © 2011 American Chemical Society.


Feng W.J.,Nanjing University of Science and Technology | Che W.Q.,Nanjing University of Science and Technology | Chang Y.M.,Nanjing University of Science and Technology | Shi S.Y.,Nanjing University of Science and Technology | Xue Q.,City University of Hong Kong
IEEE Transactions on Microwave Theory and Techniques | Year: 2013

Two high selectivity fifth-order wideband bandpass filters (BPFs) with multiple transmission zeros based on transversal signal-interaction concepts are proposed in this paper. Two transmission paths consisting of a shorted stub and two open coupled lines are used to realize signal transmission from Port 1 to Port 2. Two fifth-order wideband passbands with six and ten transmission zeros from 0 GHz to 2f0 (f0 is center frequency of the passband) can be achieved respectively due to the superposition of signals of the two transmission paths. Two prototypes with 3-dB fractional bandwidths of 61.7% (2.07-3.92 GHz) and 48.2% (2.3-3.76 GHz) are designed and fabricated for demonstration. Good agreement can be observed between simulated and measured performances. © 1963-2012 IEEE.


Yang M.,Hong Kong Polytechnic University | Zhang L.,Hong Kong Polytechnic University | Yang J.,Nanjing University of Science and Technology | Zhang D.,Hong Kong Polytechnic University
Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition | Year: 2011

Recently the sparse representation (or coding) based classification (SRC) has been successfully used in face recognition. In SRC, the testing image is represented as a sparse linear combination of the training samples, and the representation fidelity is measured by the l2-norm or l 1-norm of coding residual. Such a sparse coding model actually assumes that the coding residual follows Gaussian or Laplacian distribution, which may not be accurate enough to describe the coding errors in practice. In this paper, we propose a new scheme, namely the robust sparse coding (RSC), by modeling the sparse coding as a sparsity-constrained robust regression problem. The RSC seeks for the MLE (maximum likelihood estimation) solution of the sparse coding problem, and it is much more robust to outliers (e.g., occlusions, corruptions, etc.) than SRC. An efficient iteratively reweighted sparse coding algorithm is proposed to solve the RSC model. Extensive experiments on representative face databases demonstrate that the RSC scheme is much more effective than state-of-the-art methods in dealing with face occlusion, corruption, lighting and expression changes, etc. © 2011 IEEE.


Zhao W.,Nanjing University of Science and Technology | Zhong Q.,Nanjing University of Science and Technology
RSC Advances | Year: 2014

Oxygen vacancies are omnipresent on an oxide surface under ambient conditions. The addition of fluorine to V2O5/TiO 2 increases the number of oxygen vacancies which can react with O2 to form a superoxide species. The adsorption of NO and NH 3 on the surface of the F-doped V2O5/TiO 2 catalyst is investigated by electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). Active oxygen species formed on the surface of the catalyst are detected by EPR. At 513 K, the adsorption of NO and NH3 possibly lies in the vicinity of the surface superoxide radicals, and leads to a change in the nearby electronic structure of these sites. The present results show that F-doping can form more oxygen vacancies on the surface of the catalyst. The oxygen vacancies play an important role in the catalytic conversion of the nitrogen oxides, because they can improve the adsorption and activation of NO, NH3 and O2. Additionally, the results of NO-TPD and NH3-TPD demonstrate that there is a close correlation between the adsorption amounts of NO or NH3 and the oxygen vacancy concentrations of the catalysts. The stability and lifetime of the surface O2 - anions are directly correlated to the structure of the adsorption site on the catalyst surface and influence the catalytic ability of the catalyst to adsorb reaction gases under the NH3-SCR operating conditions. © 2014 The Royal Society of Chemistry.


Wang H.,Nanjing University of Science and Technology
Lecture Notes in Electrical Engineering | Year: 2016

Particle filter is an effective technique to deal with the state estimation of nonlinear and non Gauss dynamic systems. Aiming at the problem of moving target tracking under the condition of illumination and occlusion, a particle filter algorithm based on audio and video information fusion is studied. This algorithm overcomes the deficiency of the algorithms based on a single signal source by using the time—space relativity and the complementarity of the audio and video. Pedestrian tracking experiment based on audio and video information fusion shows that the fusion algorithm is more stable and accurate than the single video tracking algorithm. © Springer-Verlag Berlin Heidelberg 2016.


Xianming H.,Nanjing University of Science and Technology | Qin Z.,Nanjing University of Science and Technology
Energy Education Science and Technology Part A: Energy Science and Research | Year: 2011

This dissertation briefly introduces the project of the development of flue gas desulsurization (FGD) DCS simulation system on a 300MW thermal power unit in the country based on virtual technology. © Sila Science.


Shen X.,Nanjing University of Science and Technology | Sun Q.,Nanjing University of Science and Technology
Neural Processing Letters | Year: 2015

Multiset canonical correlation analysis (MCCA) can simultaneously reduce the dimensionality of multi-set data. Thus, MCCA is a very important method for multiple feature extraction. However, in small sample size problem, covariance matrix cannot be estimated accurately so that the projections in MCCA are usually not optimal in such case for recognition purpose. In order to address this problem, we propose a novel method called orthogonal MCCA based on fractional-order (FbOMCCA). Compared with MCCA, there are two improvements in FbOMCCA: firstly, orthogonality constraint, as a popular criterion used in feature extraction, is introduced. It makes multiset canonical projective vectors less affected by poor estimation of covariance matrix. Secondly, inspired with the idea of fractional order, we incorporate fractional-order within-set and between-set scatter matrices to further reduce the deviations of sample covariance matrices. Furthermore, a novel algorithm based on eigen decomposition is proposed to gradually obtain multiset canonical projective vectors. Experimental results on UCI multiple feature dataset, and CENPARMI handwritten Arabic numerals database show that FMOCCA has better recognition rates and robustness than existing MCCA-related methods. © 2014, Springer Science+Business Media New York.


Ge Q.,Nanjing University of Science and Technology | Xiao L.,Nanjing University of Science and Technology | Zhang J.,Nanjing University of Science and Technology | Wei Z.H.,Nanjing University of Science and Technology
Pattern Recognition | Year: 2012

In this paper, we propose a new region-based active contour model (ACM) for image segmentation. In particular, this model utilizes an improved region fitting term to partition the regions of interests in images depending on the local statistics regarding the intensity and the magnitude of gradient in the neighborhood of a contour. By this improved region fitting term, images with noise, intensity non-uniformity, and low-contrast boundaries can be well segmented. Integrated with the duality theory and the anisotropic diffusion process based on structure tensor, a new regularization term is defined through the duality formulation to penalize the length of active contour. By this new regularization term, the structural information of images is utilized to improve the ability of capturing the geometric features such as corners and cusps. From a numerical point of view, we minimize the energy function of our model by an efficient dual algorithm, which avoids the instability and the non-differentiability of traditional numerical solutions, e.g. the gradient descent method. Experiments on medical and natural images demonstrate the advantages of the proposed model over other segmentation models in terms of both efficiency and accuracy. © 2011 Elsevier Ltd All rights reserved.


Cui Y.,Nanjing University of Science and Technology | Cui Y.,Liaocheng University | Fan L.,Liaocheng University
Pattern Recognition | Year: 2012

In this paper, a novel supervised dimensionality reduction (DR) algorithm called graph- based Fisher analysis (GbFA) is proposed. More specifically, we redefine the intrinsic and penalty graph and trade off the importance degrees of the same-class points to the intrinsic graph and the importance degrees of the not-same-class points to the penalty graph by a strictly monotone decreasing function; then the novel feature extraction criterion based on the intrinsic and penalty graph is applied. For the non-linearly separable problems, we study the kernel extensions of GbFA with respect to positive definite kernels and indefinite kernels, respectively. In addition, experiments are provided for analyzing and illustrating our results. © 2011 Elsevier Ltd All rights reserved.


Cai W.,Nanjing University of Science and Technology | Zhong Q.,Nanjing University of Science and Technology | Zhao Y.,Nanjing University of Science and Technology
Catalysis Communications | Year: 2013

Ni/ceria-zirconia solid solution (Ni/CexZr1 - xO2) with Ce and Ni enriched on the surface of the catalysts are prepared via a simple, low-cost method. The aqueous phase reactions simplify the preparation process, save the cost and lead the Ce to enriching on the surface of products. The impregnation method makes the Ni enriching on the surface of products which enhances the efficiency of active component. These catalysts exhibit significantly high catalytic performance. The formation mechanism is also investigated. © 2013 Elsevier B.V. All rights reserved.


Jia X.,Nanjing University of Science and Technology | Tang Z.,Nanjing University of Science and Technology | Liao W.,Nanjing University of Science and Technology | Shang L.,Nanjing University
International Journal of Approximate Reasoning | Year: 2014

Decision-theoretic rough set model can derive several probabilistic rough set models by providing proper cost functions. Learning cost functions from data automatically is the key to improving the applicability of decision-theoretic rough set model. Many region-related attribute reductions are not appropriate for probabilistic rough set models as the monotonic property of regions does not always hold. In this paper, we propose an optimization representation of decision-theoretic rough set model. An optimization problem is proposed by considering the minimization of the decision cost. Two significant inferences can be drawn from the solution of the optimization problem. Firstly, cost functions and thresholds used in decision-theoretic rough set model can be learned from the given data automatically. An adaptive learning algorithm and a genetic algorithm are designed. Secondly, a minimum cost attribute reduction can be defined. The attribute reduction is interpreted as finding the minimal attribute set to make the decision cost minimum. A heuristic approach and a particle swarm optimization approach are also proposed. The optimization representation can bring some new insights into the research on decision-theoretic rough set model. © 2013 Elsevier Inc.


Huang X.-Y.,Nanjing University of Science and Technology | Hu B.-C.,Nanjing University of Science and Technology | Xu S.-C.,Nanjing University of Science and Technology
Gaodeng Xuexiao Huaxue Xuebao/Chemical Journal of Chinese Universities | Year: 2013

A novel amino acid derivatised mesoporphyrin Co(II)-[2, 7, 12, 18-tetramethyl-3, 8-diethyl-13, 17-(propionylaminoethyl-dithio-ethyaminoformylethyl)-29, 34-bis-(methoxy-formyl)]-prophyrin[Co(II)MPDTEP, V] was prepared from hemin by a six-steps reaction including deferrization, esterification, cataly-tic hydrogenation, hydrolyzation, condensation and complexation. The target products were characterized. The effects of the reaction time and temperature on the yields of the product [2, 7, 12, 18-tetramethyl-3, 8-diethyl-13, 17-(propionylaminoethyl-dithio-ethyaminoformylethyl)-29, 34-bis-(methoxy-formyl)]-prophyrin(MPDTEP, IV) were investigated. A gold electrode modified by Co(II)MPDTEP was prepared by self-assembly of disulfide on gold. The properties of the modified electrode were investigated by FTIR as well as electrochemical methods. This modified electrode was successfully used for the electrocatalytic reduction of oxygen.


Wang J.,Nanjing University of Science and Technology | Song Y.,Nanjing University of Science and Technology | Li Z.-H.,Nanjing University of Science and Technology | He A.-Z.,Nanjing University of Science and Technology
Optics Letters | Year: 2013

This Letter presents a simple radial shearing interferometery with circular gratings to measure the radial first-order derivative of arbitrary wavefront phase. Two spatial phase-shifted radial shearing interferograms can be simultaneously obtained by the system, and a two-step phase-shifting algorithm with arbitrary phase-shift value is proposed for phase retrieval. The measurement for spherical wave has shown the feasibility and validity, and the optical system is used to measure the radial first-order derivative of projection wavefront phase of a propane flame with plane incident wave. © 2013 Optical Society of America.


Huang S.,Nanjing University of Science and Technology | Xiang Z.,Nanjing University of Science and Technology
Multidimensional Systems and Signal Processing | Year: 2014

This paper investigates the problem of robust H∞ control for a class of 2-D (two-dimensional) discrete state delayed systems with sector nonlinearity described by a model of Roesser type. Firstly, a delay-dependent sufficient condition of robust exponential stability for such 2-D discrete systems is derived in linear matrix inequalities (LMIs) form. Secondly, a delay-dependent exponential stability criterion with H∞ performance for the considered systems is also proposed. Then a state feedback H∞ controller is constructed based on the above results. Finally, numerical examples are given to illustrate the effectiveness of the proposed method. © 2013 Springer Science+Business Media New York.


Meng X.,Nanjing University of Science and Technology | Li J.,Nanjing University of Science and Technology | Liu D.,Nanjing University of Science and Technology | Zhu R.,Nanjing University of Science and Technology
Optics Letters | Year: 2013

We introduce a Fourier transform imaging spectropolarimeter composed of a simultaneous polarization modulator and a Fourier transform spectrometer without slit. The spectropolarimeter enables the generation of four sets of fringe patterns with different polarization states of light from an object point. Fourier transform of the fringe patterns provides four equations of Stokes parameters in various wavenumbers. And we can obtain the full-stokes vector from the equations. The most significant advantage of the method is that the four polarized fringe patterns are obtained simultaneously and separated without aliasing. Additionally, the advantages of the Fourier transform spectrometer are maintained, such as high radiative throughput. © 2013 Optical Society of America.


Lu G.-P.,Nanjing University of Science and Technology | Cai C.,Nanjing University of Science and Technology
Advanced Synthesis and Catalysis | Year: 2013

Thioesterification can be realized via an odorless, one-pot reaction through the in situ generation of S-alkylisothiouronium salts from organic halides and thiourea in aqueous Triton X-100 (TX100) micelles. The protocol is free of foul-smell thiols and organic solvents, and operates under mild conditions, thereby offering considerable potential for applications in organic synthesis. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Li F.,Nanjing University of Science and Technology | Sun C.,Nanjing University of Science and Technology | Shan H.,Nanjing University of Science and Technology | Zou X.,Nanjing University of Science and Technology | Xie J.,Nanjing University of Science and Technology
ChemCatChem | Year: 2013

A protocol for the synthesis of N,N′-alkyl aryl ureas and N,N′-dialkyl ureas by transition metal-catalyzed regioselective N3-alkylation of the N-monosubstituted ureas with alcohols was proposed and accomplished. In the presence of an iridium/base system, the desired N,N′-alkyl aryl ureas and N,N′-dialkyl ureas were obtained with 70-93% yields, and no isomeric N1-alkylated and N3-dialkylated products were formed in all cases. From both synthetic and environmental point of views, the reaction is highly attractive because of easily available starting materials, high atom efficiency and the formation of water as the only side product. Apparently, the research opens up the design of regioselective N-alkylation of amines with alcohols based on the regioselective condensation of amines with aldehydes, facilitating the progress of the "hydrogen autotransfer" (or "hydrogen-borrowing") process. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Huang S.,Nanjing University of Science and Technology | Xiang Z.,Nanjing University of Science and Technology | Karimi H.R.,University of Agder
Circuits, Systems, and Signal Processing | Year: 2014

This paper is concerned with the problem of input-output finite-time stability (IO-FTS) for discrete impulsive switched systems with state delays. Sufficient conditions are presented for the existence of IO-FTS for such systems under the cases of certain switching, arbitrary switching, and uncertain switching. All the obtained results are formulated in a set of linear matrix inequalities (LMIs). Two numerical examples are given to illustrate the effectiveness of the proposed results. © 2013 Springer Science+Business Media New York.


Zuo C.,Nanjing University of Science and Technology | Zuo C.,Nanyang Technological University | Chen Q.,Nanjing University of Science and Technology | Qu W.,Ngee Ann Polytechnic | Asundi A.,Nanyang Technological University
Optics Letters | Year: 2013

We present an effective, fast, and straightforward phase aberration compensation method in digital holographic microscopy based on principal component analysis. The proposed method decomposes the phase map into a set of values of uncorrelated variables called principal components, and then extracts the aberration terms from the first principal component obtained. It is effective, fully automatic, and does not require any prior knowledge of the object and the setup. The great performance and limited computational complexity make our approach a very attractive and promising technique for compensating phase aberration in digital holography under time-critical environments. © 2013 Optical Society of America.


Sha Q.,Nanjing University of Science and Technology | Ling Y.,Nanjing University of Science and Technology | Wang W.,Nanjing University of Science and Technology | Wei Y.,Nanjing University of Science and Technology
Advanced Synthesis and Catalysis | Year: 2013

Copper(II) acetylacetonate-catalyzed Wittig olefination reactions of aldehydes with ketone-derived N-tosylhydrazones are reported. A series of tosylhydrazones was investigated and our results showed that the carbon number of the alkyl chain influences the E-selecivity of the alkenes greatly. Alkenes could be obtained in moderate yields and excellent E-selectivity when the carbon numbers were up to two. Under metal-free conditions, triphenylphosphine was able to capture the in situ generated diazo compounds and the corresponding unsymmetrical azines were formed in good yields. © 2013 Wiley-VCH Verlag GmbH&Co. KGaA, Weinheim.


Zhang X.,Nanjing University of Science and Technology | Liu C.,Nanjing University of Science and Technology
Multidimensional Systems and Signal Processing | Year: 2014

This paper introduces a scale-invariant and contrast-invariant multi-scale differential edge detector. The method is a direct consequence of two key discoveries: (1) a precise scale normalization method and (2) a formula to verify scale-invariant detectors. The new scale normalization method provides differential operators with respect to scale, among them the scale-invariant edge detectors. To investigate these differential detectors quantitatively, mathematical functions were used to represent the edges and to solve for the parameters, including position, width, contrast, offset, and orientation, in closed form. Noise is filtered as a low-contrast feature. The method has been tested with various kinds of synthesized edge functions and can extract edge features accurately. It is suitable for real-world images of several kinds of degradation. © 2013 Springer Science+Business Media New York.


Zuo C.,Nanjing University of Science and Technology | Zuo C.,Nanyang Technological University | Chen Q.,Nanjing University of Science and Technology | Asundi A.,Nanyang Technological University
Optics Express | Year: 2014

The transport of intensity equation (TIE) is a two-dimensional second order elliptic partial differential equation that must be solved under appropriate boundary conditions. However, the boundary conditions are difficult to obtain in practice. The fast Fourier transform (FFT) based TIE solutions are widely adopted for its speed and simplicity. However, it implies periodic boundary conditions, which lead to significant boundary artifacts when the imposed assumption is violated. In this work, TIE phase retrieval is considered as an inhomogeneous Neumann boundary value problem with the boundary values experimentally measurable around a hard-edged aperture, without any assumption or prior knowledge about the test object and the setup. The analytic integral solution via Green's function is given, as well as a fast numerical implementation for a rectangular region using the discrete cosine transform. This approach is applicable for the case of non-uniform intensity distribution with no extra effort to extract the boundary values from the intensity derivative signals. Its efficiency and robustness have been verified by several numerical simulations even when the objects are complex and the intensity measurements are noisy. This method promises to be an effective fast TIE solver for quantitative phase imaging applications. © 2014 Optical Society of America.


Wang S.,Nanjing University of Science and Technology | Shen R.,Nanjing University of Science and Technology | Ye Y.,Nanjing University of Science and Technology | Hu Y.,Nanjing University of Science and Technology
Nanotechnology | Year: 2012

An investigation into the ignitions and combustions of porous silicon (PS) nanoenergetic material array chips (nECs) at different ignition voltages was performed. The PS nECs were fabricated by integrating PS nanoenergetic material (nEMs) matrices and Cr-microbridges (microigniters) on the surface of silicon substrates. The combustion of PS nECs was in ambient air. Its ignition and combustion were investigated by a testing system and an optical high-speed camera. Experimental results revealed that the combustion delay time of PS nEMs increased from 8.0×10 5s to 1.1×10 4s with the decrement of ignition voltages from 140 to 80V. The scope of ignition energy ranged from 0.153 to 0.287mJ by calculations. The reaction type was deflagration, from the analysis of the high-speed video of PS nECs. The comprehensive experimental results indicated that the combustion of PS nECs was ignited by the synergic effect of the heat and the plasma. The ignition experiments suggested that Cr-microbridges were reliable igniters to trigger the self-sustained combustion of PS nECs. The strong plume of flame emitted from the surface of PS nECs indicated that the PS nECs may be applied as micro/nano igniter chips and microthruster chips. © 2012 IOP Publishing Ltd.


Pan S.,Nanjing University of Science and Technology | Liu X.,Nanjing University of Science and Technology
New Journal of Chemistry | Year: 2012

We report an approach for preparation of CdS-graphene nanocomposite via a hydrothermal method. In this process, graphene oxide was reduced to graphene which assists in forming CdS nanoparticles. The adsorption kinetics data is in good agreement with pseudo-second-order kinetic model. Furthermore, the CdS-graphene reveals a high photodegradation rate under visible light irradiation. This journal is © 2012 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.


Zhang S.-P.,Nanjing University of Science and Technology | Song H.-O.,Nanjing University
New Journal of Chemistry | Year: 2012

Supramolecular hybrid materials of graphene oxide (GO) with octadecylamine or dodecylamine have been fabricated by a simple self-assembly technique at room temperature. Many characterization methods have been used to research the micelle-like nanostructures. Compared to unmodified GO, the alkyl-functionalized graphene hybrids could be easily dispersed in various nonpolar organic solvents, such as petroleum ether, n-heptane, isooctane, dimethylbenzene etc., rather than in polar solvents. It was found that alkylamine plays a key role during such preparation. Octadecanol (ODO) produced hardly any modification of GO under the conditions, because the so-called product (GO-ODO) exhibits a high degree of similarity to GO in solvent dispersion behaviour and the Fourier transform infrared spectroscopy. The addition of alkylamine significantly improves the thermal stability of the nanomaterials. The improved thermal degradation temperatures can be obtained for polyethylene glycol and polymethyl methacrylate after filling it with as little as 1 wt% of the hybrid, suggesting their great potential as novel nanofillers in industry. This journal is © 2012 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.


Wang A.,Nanjing University of Science and Technology | Long L.,Jiangsu University | Zhang C.,Nanjing University of Science and Technology
Journal of Inclusion Phenomena and Macrocyclic Chemistry | Year: 2011

Phthalocyanines (Pcs) can very well satisfy the different demands of photosensitizer in photodynamic therapy (PDT) such as absorption, amphiphilicity and most importantly, high photochemical reactivity, depending on the subtle interplay of structure-function relationships. They have been shown to be phototoxic against a number of tumor cells. Certain criteria of ideal photosensitizers for PDT were described. A brief summary of the synthesis and some properties of photo-activable Pcs have been presented and an outlook for future photocytotoxic Pcs given. These Pcs are classified into three groups: (1) Pcs with different peripheral and/or non-peripheral substitution; (2) Pcs with different axial substitution; (3) Pcs with different metal center. © 2011 Springer Science+Business Media B.V.


Zhang H.,Tongji University | Zhang H.,City University of Hong Kong | Feng G.,City University of Hong Kong | Feng G.,Nanjing University of Science and Technology | And 2 more authors.
IEEE Transactions on Industrial Electronics | Year: 2014

This paper studies the consensus problem of linear multi-agent systems via observer-based event-triggered control. Two novel observer-based event-triggered control schemes, one centralized and the other distributed, are developed. It is shown that under the proposed control protocols, consensus can be reached if the underlying communication graph of the MAS is connected. An example is finally presented to illustrate the effectiveness of the proposed control methods. © 1982-2012 IEEE.


Qi S.-S.,Nanjing University of Science and Technology | Wu W.,Nanjing University of Science and Technology | Fang D.-G.,Nanjing University of Science and Technology
IEEE Transactions on Antennas and Propagation | Year: 2013

A singly-fed circular aperture antenna radiating left-hand circularly polarized conical beam is proposed. The circularly polarized characteristic is realized by exciting TM01 and TE01 modes in a circular waveguide simultaneously. Through optimized design, the antenna provides an impedance bandwidth (|S11| <-10 dB) of 5%, from 12.15 to 12.8 GHz, and an axial ratio bandwidth (AR 3 dB) of 4.8%, from 12.2 to 12.8 GHz. At the central frequency 12.5 GHz, a flare angle of 28° of the radiation pattern and a measured gain of 7.5 dBic have been achieved. Good agreement has been observed between simulated results and measured ones. © 2013 IEEE.


Feng W.,Nanjing University of Science and Technology | Che W.,Nanjing University of Science and Technology | Ma Y.,Nanjing University of Science and Technology | Xue Q.,City University of Hong Kong
IEEE Microwave and Wireless Components Letters | Year: 2013

A new compact wideband differential bandpass filters with wideband common mode suppression using half-wavelength ring resonator is presented in this letter. Five-order passband for the wideband differential mode with two transmission zeros close to the passband is realized with four open stubs. A planar wideband differential filter (3 dB fractional bandwidth 79%) with wideband common mode suppression is designed and fabricated. The theoretical and measured results agree well and show good in-band filtering performances and high selectivity. © 2001-2012 IEEE.


Chen H.,Nanjing University of Science and Technology | Yan T.,Nanjing University of Science and Technology | Jiang F.,Nanjing University of Science and Technology
Journal of the Taiwan Institute of Chemical Engineers | Year: 2014

Mesoporous carbon nitride (MCN) was synthesized using mesoporous silica SBA-15 as the template and employed for the adsorption of Cr(VI) from aqueous solutions. Cr(VI) adsorption over MCN followed pseudo-second-order kinetic model and the Langmuir adsorption model. The maximum sorption capacity of MCN for Cr(VI) was 48.31. mg/g at pH 5.7, higher than activated carbon (AC) and ordered mesoporous carbon (CMK-3). An electrostatic interaction mechanism between Cr(VI) and surface pyridine groups on MCN was proposed by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) analysis. The coexisting anions, especially the carbonate, influenced the adsorption amount due to the competitive adsorption of Cr(VI) on the surface of MCN. The adsorbed Cr(VI) could be effectively desorbed by 0.5. mol/L NaOH solution, suggesting that MCN could be a promising adsorbent for Cr(VI) removal from waste effluents. © 2014 Taiwan Institute of Chemical Engineers.


Ji F.,Nanjing University of Science and Technology | Lv M.-F.,Nanjing University of Science and Technology | Yi W.-B.,Nanjing University of Science and Technology | Cai C.,Nanjing University of Science and Technology
Advanced Synthesis and Catalysis | Year: 2013

A novel and efficient domino process has been developed for the synthesis of 1,4-benzoxazepine derivatives from a range of readily accessible N-tosylaziridines, 2-iodophenols and isocyanides. This process involves the aziridine ring-opening reaction with 2-iodophenol, followed by a palladium-catalyzed isocyanide-insertion reaction. This regioselective and high-yielding transformation could be extended to its application for the synthesis of natural products and biologically interesting heterocycles. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Ge W.,Nanjing University of Science and Technology | Zhu X.,Yancheng Textile Vocational Technology College | Wei Y.,Nanjing University of Science and Technology
Advanced Synthesis and Catalysis | Year: 2013

Iodine-catalyzed intermolecular dehydrogenative aromatizations of six-membered cyclohexanones for the selective synthesis of 2-sulfanylphenols have been developed. Both aryl and alkyl disulfides can be used as sulfanylation reagents to give the desired products in good yields under the optimized reaction conditions. The catalytic reaction uses dimethyl sulfoxide or oxygen as the terminal oxidant and avoids the use of transition metal catalysts. In addition, a-sulfanyl enones could also be obtained via an iodine-catalyzed oxidative system from simple cyclic ketones using dimethyl sulfoxide as the oxidant. © 2013 Wiley-VCH Verlag GmbH&Co. KGaA, Weinheim.


Zhang L.,Nanjing University of Science and Technology
China International Conference on Electricity Distribution, CICED | Year: 2014

Ice-shedding occurs frequently on overhead transmission line in ice area, causing vibration on the line and making it jump up and down violently. In heavy icing areas and long-span cases, the effects of ice-shedding are especially serious. This paper reviewed the research status about t he type of the grid failure caused from ice-shedding, factors affecting the conductor's ice-shedding, the analysis model and other aspects of prevention and control measures. The research trends based on current research situation study are also proposed to provide a reference for our country's study on ice shedding. © 2014 IEEE.


Zhang J.-K.,McMaster University | Fei H.,Nanjing University of Science and Technology
IEEE Signal Processing Letters | Year: 2010

In this letter, a necessary and sufficient condition is developed to check whether a set of polynomial equations is solvable. Furthermore, under the sufficient condition, a closed-form solution is attained using linear Diophantine equation theory. With this, a novel signal design and a row-circular transmission scheme of phase shift keying (PSK) constellations for MIMO flat fading channels are proposed so that the channel coefficients can be uniquely identified. When certain high-order moments of the received signals are available, a closed-form solution to uniquely determine the channel coefficients is given. When only finite received data are available, a numerical algorithm is provided to efficiently and effectively estimate the channel. © 2006 IEEE.


Wang X.,Changshu Institute of Technology | Qian H.,Nanjing University of Science and Technology
International Journal of Communication Systems | Year: 2015

The paper proposes a dynamic and hierarchical IPv6 address configuration scheme for a mobile ad hoc network (MANET). The scheme proposes the hierarchical architecture and combines the distributed and centralized address configuration approaches. In the architecture, a central node assigns IPv6 addresses for cluster heads that are distributed around a MANET, and distributed cluster heads assign IPv6 addresses for cluster members. The generation algorithm of a cluster is proposed, and it uses the number of potential cluster members as a measurement unit and minimizes the number of cluster heads. Therefore, the address confi guration cost for cluster heads is reduced. A central node/cluster head uses the unicast communication mode to achieve the real-time address recovery in order to ensure that it has enough address resources for assignment. The paper also proposes the low-cost MANET merging/ partitioning algorithm that guarantees that no address collision happens during the MANET merging/ partitioning process. This paper analyzes the performance parameters of the proposed scheme, including the address configuration cost, the address configuration delay, and the number of MANET merging. The analytical results show that the proposed scheme effectively reduces the address configuration cost, shortens the address configuration delay, and decreases the number of MANET merging. Copyright © 2013 John Wiley & Sons, Ltd.


Xu H.,Nanjing University of Science and Technology | Zou Y.,Nanjing University of Science and Technology
International Journal of Systems Science | Year: 2011

This article considers the problem of H ∞ control for two-dimensional (2-D) singular delayed systems in Roesser models. The problem to be addressed is the design of a state feedback controller such that the acceptability, internal stability and causality of the resulting closed-loop system is guaranteed and a prescribed H ∞ performance level is ensured. In terms of a linear matrix inequality (LMI), a sufficient condition for the solvability of the problem is obtained. A desired state feedback controller can be designed by solving a certain LMI. A numerical example is provided to demonstrate the application of the proposed method. © 2011 Taylor & Francis.


Li Y.-Y.,Nanjing University of Science and Technology | Qi G.-Q.,Nanjing University of Science and Technology | Sheng A.-D.,Nanjing University of Science and Technology
Journal of Process Control | Year: 2011

Abstract: This paper focuses on a graphical approach to determine the region of proportional-integral-derivative (PID) controllers in the parameter space for which the closed-loop system is internally stable and the H ∞ optimization criteria are satisfied for a class of single-input single-output arbitrary order plant with or without dead time. Unlike conventional methods which the analytical models, such as transfer functions and state space models, are needed, the design information of the proposed approach is only the frequency response data, which are directly calculated from a single relay test for stable plants, or extracted from the closed-loop system frequency response data by dividing out the known stabilizing compensator for unstable plants using relay feedback methods. It is shown that the problem to be solved can be translated into simultaneous stabilization of the closed-loop characteristic function and a family of characteristic functions. Based on the technique of D-decomposition, the analytical boundaries of root invariant regions are derived and the admissible H∞ region in the parameter space is the intersection of the admissible sets, and it can be drawn and identified immediately, not to be computed mathematically. A practical algorithm of determining the H∞ region is proposed and two examples are used to illustrate the proposed method. © 2011 Elsevier Ltd. All rights reserved.


Huang S.,Nanjing University of Science and Technology | Xiang Z.,Nanjing University of Science and Technology
Automatica | Year: 2016

This paper investigates the finite-time stabilization of a class of switched stochastic nonlinear systems in p-normal form, where the power orders of the system are dependent upon the switching signal and the system structure is in non-triangular form. Compared with the existing results, some power orders of the system are allowed to be even. Under suitable assumptions, a state feedback control law with state-dependent switching is designed by using the convex combination method and the adding a power integrator technique. It is shown that the resulting closed-loop system is finite-time stable in probability. Simulation results of a continuously stirred tank reactor (CSTR) system are provided to show the effectiveness and applicability of the proposed method. © 2016 Elsevier Ltd


Cai M.,Nanjing University of Science and Technology | Xiang Z.,Nanjing University of Science and Technology
Neurocomputing | Year: 2015

This paper investigates the adaptive finite-time stabilization of a class of switched nonlinear systems with unknown nonlinear terms using neural networks. Under the assumption that all the growth conditions for the unknown nonlinear perturbation functions are partially known, the common finite-time controller and adaptive law are constructed by extending the adding-a-power-integrator technique and using the backstepping methodology. The unknown parts of the growth conditions are modeled by the neural networks and the known parts are exploited for the controller design. The bounds of neural network approximation errors are assumed to be unknown and are estimated online. It is shown that the state of the closed-loop system is finite-time stable and the parameter estimations are bounded under arbitrary switching. A simulation example is provided to show the effectiveness of the proposed method. © 2014 Elsevier B.V.


Li J.,Nanjing University of Science and Technology | Zhu J.,Nanjing University of Science and Technology | Liu X.,Nanjing University of Science and Technology
Dalton Transactions | Year: 2014

Ethylene glycol (EG) has been widely utilized to fabricate silver nanoparticles with uniform size and morphology. However, the majority of the work reported to date using EG routinely require not only heating, but also a surfactant. In the present paper, we report a surfactant-free and facile method for the synthesis of fairly monodisperse smaller silver nanoparticles (∼6 nm) through the reaction of silver ions with EG by using tungstates (such as potassium tungstate, sodium tungstate) as catalysts at room temperature. Particularly, in this method, tungstates as catalysts can dramatically speed up the reduction of silver ions, and EG acts as both a solvent and a reducing agent to reduce silver ions to Ag metal. Meantime, we have carried out a series of experiments to investigate the performance of the as-prepared silver nanoparticles. It was found that the silver nanoparticles show excellent catalytic activity for the reduction of 4-nitrophenol in the presence of NaBH4. © 2014 The Royal Society of Chemistry.


Zhu Y.,Nanjing University of Science and Technology
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2011

In the case that a system is affected by fuzzy factors, a fuzzy optimal-control problem is proposed. A fuzzy optimal-control problem for a multistage fuzzy system is considered to optimize the expected value of a fuzzy objective function subject to a multistage fuzzy system where, at every stage, the system is disturbed by a fuzzy variable. Based on Bellman's Principle of Optimality, a recurrence equation for the problem is presented. A linear quadratic fuzzy optimal-control problem is shown to have an exact solution by the recurrence equation if the system is affected by triangular fuzzy variables. For general cases, two methods, the hybrid intelligent algorithm and the finite-search method, are established to approximate the solutions of the problem. Finally, an example is used to show that these two methods are effective to solve a fuzzy optimal-control problem for a multistage fuzzy system. © 2011 IEEE.


Yuan D.,Nanjing University of Science and Technology | Xu S.,Nanjing University of Science and Technology | Zhao H.,Nanjing University of Science and Technology
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2011

This paper studies the problem of optimizing the sum of multiple agents' local convex objective functions, subject to global convex inequality constraints and a convex state constraint set over a network. Through characterizing the primal and dual optimal solutions as the saddle points of the Lagrangian function associated with the problem, we propose a distributed algorithm, named the distributed primal-dual subgradient method, to provide approximate saddle points of the Lagrangian function, based on the distributed average consensus algorithms. Under Slater's condition, we obtain bounds on the convergence properties of the proposed method for a constant step size. Simulation examples are provided to demonstrate the effectiveness of the proposed method. © 2006 IEEE.


Zhao Y.-P.,Nanjing University of Science and Technology | Sun J.-G.,Nanjing University of Aeronautics and Astronautics
Expert Systems with Applications | Year: 2011

In many real life realms, many unknown systems own different data trends in different regions, i.e.; some parts are steep variations while other parts are smooth variations. If we utilize the conventional kernel learning algorithm, viz. the single kernel linear programming support vector regression, to identify these systems, the identification results are usually not very good. Hence, we exploit the nonlinear mappings induced from the kernel functions as the admissible functions to construct a novel multikernel semiparametric predictor, called as MSLP-SVR, to improve the regression effectiveness. The experimental results on the synthetic and the real-world data sets corroborate the efficacy and validity of our proposed MSLP-SVR. Meantime, compared with other multikernel linear programming support vector algorithm, ours also takes advantages. In addition, although the MSLP-SVR is proposed in the regression domain, it can also be extended to classification problems. © 2010 Elsevier Ltd. All rights reserved.


Wang M.-X.,Nanjing University of Science and Technology
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2015

The primary nucleation and crystal growth of a single chain from different dilute solution are studied by Monte Carlo simulations. The interplay of crystallization and demixing/collapse is conveniently investigated in chain folding. We find the solvent qualities affect the nucleation mechanism, crystal morphology and the thickening process. In good solution the swollen coil allows the stems more extended and facilitates to form thicker crystalline stems. The poor solvent condition is helpful to perform fast nucleation and produce a dense crystal. But to get more reorganization the critical athermal solution is the best choice, where the longitudinal thickening and width contraction of the folded stem is well coupled. Our results may complement the kinetic mechanism of crystal growth beyond the point of lamellar thickening. © 2015 Elsevier B.V.


Chen G.,Nanjing University of Science and Technology | Fang G.L.,Nanjing University of Science and Technology | Tang G.D.,Nanjing University of Science and Technology
Materials Research Bulletin | Year: 2013

Nanostructured BiOCl and Bi24O31Cl10 have been synthesized by electrolytic corrosion of metal Bi. The photocatalysis and photoluminescence (PL) properties of BiOCl and Bi24O 31Cl10 nanostructures have been investigated. Nanosheets with a thickness of ∼10 nm and in-plane size of 30-60 nm were obtained in the as-synthesized BiOCl. The emission spectra excited at 360 nm consist of two broad emission bands: ultraviolet-blue and visible. The visible emission is responsible for the photocatalytic activity of BiOCl under visible light irradiation. The nanostructured Bi24O31Cl10, self-assembled by uniform nanosheets with a thickness of 10-20 nm, exhibits a broad and strong blue shift UV emission at room temperature. © 2012 Elsevier Ltd. All rights reserved.


Zhang J.,Nanjing University of Science and Technology | Wang H.,Nanjing University of Science and Technology | Zhu X.,Nanjing University of Science and Technology
IEEE Transactions on Signal Processing | Year: 2010

The colocated uniform linear array (ULA) multiple-input multiple-output (MIMO) radar has been demonstrated to provide enhanced performance in theory. Similar to a bistatic radar, performance of the separated transmit/receive (STR) ULA-MIMO radar is affected not only by the transmitted multiple orthogonal waveforms, but also by the position of the target. In this correspondence, the ambiguity function of the STR-ULA-MIMO radar is investigated and the corresponding range-velocity ambiguity function (RVAF) is deduced. The range and velocity resolution of RVAF for the STR-ULA-MIMO radar is discussed. Because the shape of RVAF for the STR-ULA-MIMO radar is related to the position of the target, a new algorithm for adaptively designing the orthogonal frequency-hopping waveforms according to the position of the target is proposed. This algorithm improves the range and velocity resolution and the integrated sidelobe level (ISL) of the matched filter output at the corresponding position. © 2006 IEEE.


Shi C.,Nanjing University of Science and Technology | Wang Y.,Harbin University of Science and Technology | Yang J.,Nanjing University of Science and Technology
Robotics and Autonomous Systems | Year: 2010

Local obstacle avoidance is a principle capability for mobile robots in unknown or partially known environment. A series of velocity space methods including the curvature velocity method (CVM), the lane curvature method (LCM) and the beam curvature method (BCM) formulate the local obstacle avoidance problem as one of constrained optimization in the velocity space by taking the physical constraints of the environment and the dynamics of the vehicle into account. We present a new local obstacle avoidance approach that combines the prediction model of collision with the improved BCM. Not only does this method inherit the quickness of BCM and the safety of LCM, but also the proposed prediction based BCM (PBCM) can be used to avoid moving obstacles in dynamic environments. © 2010 Elsevier B.V. All rights reserved.


Li J.,Nanjing University of Science and Technology | Liu X.,Nanjing University of Science and Technology
Materials Letters | Year: 2013

In this work, we introduce a simple approach to synthesize orthorhombic MoO3 (α-MoO3) nanobelts with dichloromethane (CH2Cl2). More importantly, dichloromethane acts as a reagent to slowly provide H+ through hydrolysis, which facilitates to manipulate the morphology of the as-obtained products. The electrochemical properties of the samples were analyzed using cyclic voltammetry and chronopotentiometry. The results show that the maximum specific capacitance of the α-MoO3 nanobelts is much higher than those of MoO 3 nanoplates with 280 F g-1, MoO3 nanowires with 110 F g-1 and MoO3 nanorods with 30 F g-1. Furthermore, the charge-discharge stability measurements indicate a retention of specific capacitance of about 90% after 500 cycles at a current density of 0.25 A g-1, demonstrating that the α-MoO3 nanobelts can serve as excellent electrode materials for supercapacitors. © 2013 Elsevier B.V.


Zhang L.,Nanjing University of Science and Technology | Han G.,Nanjing University of Science and Technology | Liu Y.,Nanjing University of Science and Technology | Tang J.,Nanjing University of Science and Technology | Tang W.,Nanjing University of Science and Technology
Sensors and Actuators, B: Chemical | Year: 2014

A method is reported for the preparation of novel electrode by layer-by-layer assembly of haemoglobin (Hb), gold (Au) nanoparticles, chitosan (CS) and graphene (GR) onto glassy carbon electrode (GCE). The Au/GR-CS substrate shows an obvious promotion for the direct electron transfer between Hb and GCE. The surface concentration.


Wang F.,Nanjing University of Science and Technology | Gu Z.,Nanjing University of Science and Technology | Lei W.,Nanjing University of Science and Technology | Wang W.,Nanjing University of Science and Technology | And 2 more authors.
Sensors and Actuators, B: Chemical | Year: 2014

Graphene quantum dots (GQDs) have been attractive due to their optical properties with the change of the size. The stable blue fluorescent GQDs are prepared via the hydrothermal method using reoxidized graphene oxide. Based on the quenching of as-prepared GQDs fluorescence by Cu(II) in water, a facile and direct fluorescence sensor for the detection of Cu2+ ions has been studied. It exhibits an extraordinarily high sensitivity and selectivity to Cu2+ ions compared to other metal ions in aqueous solution. The fluorescence intensity is inversely proportional to the concentration of Cu 2+ ions, and the calibration curve displays linear regions over the range of 0-15 μM, with a detection limit of 0.226 μM. These results indicate that GQDs, as a fluorescent sensing platform, could meet the selective requirements for biomedical and environmental application and be sensitive enough to detect Cu2+ ions in environmental water samples, even in drinking water, which has a limit of 20 μM defined by the U.S. Environmental Protection Agency. The possible mechanism of Cu(II)-induced fluorescence quenching of GQDs was also discussed. The fluorescence lifetime experimental result demonstrates that the quenching mechanism appears to be predominantly of the static (rather than dynamic) type.© 2013 Elsevier B.V. All rights reserved.


Zhu Y.,Nanjing University of Science and Technology | Gao W.,Nanjing University of Science and Technology
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2014

A novel full-field optical coherence tomography (FFOCT) system with low cost and high resolution is developed for imaging of cells and tissues. Different from other FFOCT systems illuminated with optical fiber bundle, the improved Köhler illumination arrangement with a halogen lamp is used in the proposed FFOCT system. High numerical aperture microscopic objectives are used for imaging and a piezoelectric ceramic transducer (PZT) is used for phase-shifting. En-face tomographic images can be obtained by applying the five-step phase-shifting algorithm to a series of interferometric images which are recorded by a smart charge coupled device (CCD) camera. Three-dimensional images can be generated from these tomographic images. Imaging of the chip of Intel Pentium 4 processor demonstrats the ultrahigh resolution of the system (lateral resolution 0.8 μm), approaching the theoretical resolution 0.7 μm×0.5 μm (lateral×axial). En-face images of cells of onion surface and potted plant leaves cells show the excellent performance of the system for generating en-face images of biological tissues. The system is characterized by its high resolution, low cost and simple arrangement for adjustment, providing a practical method of performing FFOCT imaging.


Yin J.,Nanjing University of Science and Technology | Chaitanya K.,Nanjing University of Science and Technology | Ju X.-H.,Nanjing University of Science and Technology
Journal of Materials Chemistry C | Year: 2015

A novel crystal structure of octaseleno[8]circulene (C16Se8, we named it "selflower") was predicted on the basis of a sym-tetraselenatetrathio[8]circulene crystal (C16S4Se4, selenosulflower). The charge transport properties of selenosulflower and its selenium analogue of selflower as potential ambipolar materials were investigated by the density functional theory (DFT) coupled with the incoherent charge-hopping model. Insights into their geometric and electronic structures, frontier molecular orbitals, reorganization energies and transfer integrals, anisotropic mobilities as well as band structures of the two novel materials are provided in detail. The gap of the frontier molecular orbitals decreases when all sulfur atoms of C16S4Se4 are substituted by selenium, which improves the charge transfer efficiency. The predicted hole and electron mobilities of C16Se8 are 1.03 and 1.26 cm2 V-1 s-1, respectively. C16S4Se4 has a hole mobility of 0.49 cm2 V-1 s-1 and an electron mobility of 0.74 cm2 V-1 s-1. Both circulenes exhibit electron-dominated ambipolar performance. The small reorganization energy and larger transfer integral originating from the face to face π-π stacking lead to large charge mobility for the novel compound C16Se8. From the viewpoint of transfer integral, the electron coupling among the dominant hopping pathways indicates that the charge transport processes take place in the parallel dimers with π-π interaction. The two materials exhibit a remarkable angular dependence of mobilities and anisotropic behaviors. The newly designed "selflower" C16Se8 is a novel organic semiconductor and worth synthesizing. This journal is © The Royal Society of Chemistry 2015.


Hui J.N.,Nanjing University of Science and Technology | Feng W.J.,Nanjing University of Science and Technology | Che W.Q.,Nanjing University of Science and Technology
Electronics Letters | Year: 2012

A compact multilayer substrate integrated waveguide (SIW) balun bandpass filter is proposed. A 180° reverse phase characteristic between the input/output ports can be easily achieved by the middle metal-ground of the SIW power divider. Four inductive posts are added to the multilayer SIW power divider to realise a passband. Good in-band balance performance (amplitude and phase imbalance are less than 0.35dB and 2°) over the passband are achieved for the balun bandpass filter. © 2012 The Institution of Engineering and Technology.