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Showing papers by "Nanjing University of Science and Technology published in 2011"


Proceedings ArticleDOI
20 Jun 2011
TL;DR: The robust sparse coding (RSC) scheme is proposed, which 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.
Abstract: 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 l 2 -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.

601 citations


Journal ArticleDOI
TL;DR: A magnetically separable ZnFe2O4-graphene nanocomposite photocatalyst with different graphene content was prepared by a facile one-step hydrothermal method as discussed by the authors.
Abstract: A magnetically separable ZnFe2O4–graphene nanocomposite photocatalyst with different graphene content was prepared by a facile one-step hydrothermal method. The graphene sheets in this nanocomposite photocatalyst are exfoliated and decorated with ZnFe2O4 nanocrystals. It was found that in the presence of H2O2, the photodegradation rate of methylene blue (MB) was 88% after visible light irradiation for only 5 min and reached up to 99% after irradiation for 90 min. In comparison with pure ZnFe2O4 catalyst, ZnFe2O4–graphene serves a dual function as the catalyst for photoelectrochemical degradation of MB and the generator of a strong oxidant hydroxyl radical (·OH) via photoelectrochemical decomposition of H2O2 under visible light irradiation. ZnFe2O4 nanoparticles themselves have a magnetic property, which makes the ZnFe2O4–graphene composite magnetically separable in a suspension system, and therefore it does not require additional magnetic components as is the usual case.

509 citations


Journal ArticleDOI
TL;DR: A two-phase test sample representation method for face recognition using the representation ability of each training sample to determine M “nearest neighbors” for the test sample and uses the representation result to perform classification.
Abstract: 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.

498 citations


Journal ArticleDOI
TL;DR: 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.
Abstract: 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.

320 citations


Journal ArticleDOI
TL;DR: In this article, a general method of describing the spin-lattice interactions in magnetic solids is proposed in terms of first-principles calculations, and the ground-state structure of a representative spin-frustrated spinel is tetragonally distorted, in agreement with experiments.
Abstract: 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${}_{2}$O${}_{4}$, 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.

245 citations


Journal ArticleDOI
TL;DR: It is found that the electrode surface decorated with an aptamer probe-pendant tetrahedral DNA nanostructure greatly facilitates cocaine-induced fusion of the split anticocaine aptamer, leading to a sensitive cocaine sensor with a remarkably low detection limit of 33 nM.
Abstract: The sensitivity of aptamer-based electrochemical sensors is often limited by restricted target accessibility and surface-induced perturbation of the aptamer structure, which arise from imperfect packing of probes on the heterogeneous and locally crowded surface. In this study, we have developed an ultrasensitive and highly selective electrochemical aptamer-based cocaine sensor (EACS), based on a DNA nanotechnology-based sensing platform. We have found that the electrode surface decorated with an aptamer probe-pendant tetrahedral DNA nanostructure greatly facilitates cocaine-induced fusion of the split anticocaine aptamer. This novel design leads to a sensitive cocaine sensor with a remarkably low detection limit of 33 nM. It is also important that the tetrahedra-decorated surface is protein-resistant, which not only suits the enzyme-based signal amplification scheme employed in this work, but ensures high selectivity of this sensor when deployed in sera or other adulterated samples.

224 citations


Journal ArticleDOI
TL;DR: In this paper, the inverted configuration OSCs with high work function metal as top cathode could improve OSC's lifetime, i.e., protecting cells from the damage by oxygen and moisture in air.

212 citations


Journal ArticleDOI
01 Dec 2011
TL;DR: A distributed algorithm is proposed, named the distributed primal-dual subgradient method, to provide approximate saddle points of the Lagrangian function, based on the distributed average consensus algorithms, and bounds on the convergence properties of the proposed method are obtained.
Abstract: 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.

210 citations


Journal ArticleDOI
TL;DR: 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 oximine and subsequent functionalization with alkynes.
Abstract: 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.

207 citations


Journal ArticleDOI
TL;DR: In this paper, a BiVO4-graphene photocatalyst was prepared by a facile one-step hydrothermal method and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman Spectroscopy, XPS, and transmission electron microscopy (TEM) techniques.

187 citations


Journal ArticleDOI
TL;DR: QSAR study revealed that the presence of electron-withdrawing groups in B-ring and electron-donating groups in A-ring of chalcones was important for inhibition of LPS-induced IL-6 expression, and showed a series of anti-inflammatory chalcone derivatives with potential therapeutic effects in inflammatory diseases.
Abstract: Major anti-inflammatory agents, steroids and cyclooxygenase, were proved to have serious side effects. Here, a series of chalcone derivatives were synthesized and screened for anti-inflammatory activities. QSAR study revealed that the presence of electron-withdrawing groups in B-ring and electron-donating groups in A-ring of chalcones was important for inhibition of LPS-induced IL-6 expression. Further, compounds 22, 23, 26, 40, and 47 inhibited TNF-α and IL-6 release in a dose-dependent manner and decreased LPS-induced TNF-α, IL-1β, IL-6, IL-12, and COX-2 mRNA production. Mechanistically, compounds 23 and 26 interfered with JNK/NF-κB signaling and dose-dependently prevented ERK and p38 activation. In addition, 23 and 26 exhibited a significant protection against LPS-induced death and were able to block high glucose-activated cytokine profiles in macrophages. Together, these data show a series of anti-inflammatory chalcones with potential therapeutic effects in inflammatory diseases.

Journal ArticleDOI
TL;DR: In this paper, the structural and optical properties of ZnO thin films with different thickness were studied by X-ray diffractometer, atomic force microscope, UV-visible spectrophotometer, ellipsometer and fluorophotometer.

Journal ArticleDOI
TL;DR: A novel binary classifier coined projection twin support vector machine (PTSVM) is proposed to seek two projection directions, one for each class, such that the projected samples of one class are well separated from those of the other class in its respective subspace.

Journal ArticleDOI
TL;DR: In this article, the carbon-supported Pd-Au/C catalysts with different alloying degree are prepared in the aqueous solution with and without tetrahydrofuran (THF) by a chemical reduction method.
Abstract: The carbon-supported Pd–Au catalysts (Pd–Au/C) with different alloying degree are prepared in the aqueous solution with and without tetrahydrofuran (THF) by a chemical reduction method. The studies of X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) measurements show that the alloying degree of the Pd–Au/C catalyst prepared in the aqueous solution is much lower than that of Pd–Au/C catalyst prepared in the H 2 O/tetrahydrofuran (THF) mixture solution, indicating the presence of THF can obviously enhance the alloying degree of Pd–Au nanoparticles during the preparation of Pd–Au/C catalyst. The electrochemical measurements illustrate the electrocatalytic activity of Pd–Au/C catalyst for the formic acid electrooxidation is strongly dependent on alloying degree of Pd–Au nanoparticles. The Pd–Au/C catalyst with high alloying degree shows a higher electrocatalytic activity and stability for the formic acid electrooxidation compared to the Pd–Au/C catalyst with low alloying degree, which can be ascribed to enhancement of CO tolerance and possible suppression of dehydration pathway in the course of formic acid electrooxidation.

Journal ArticleDOI
TL;DR: Experimental results demonstrate that the proposed modification achieves better results in terms of both peak signal-to-noise ratio and subjective visual quality than the original method for strong noise.
Abstract: In order to resolve the problem that the denoising performance has a sharp drop when noise standard deviation reaches 40, proposed to replace the wavelet transform by the DCT. In this comment, we argue that this replacement is unnecessary, and that the problem can be solved by adjusting some numerical parameters. We also present this parameter modification approach here. Experimental results demonstrate that the proposed modification achieves better results in terms of both peak signal-to-noise ratio and subjective visual quality than the original method for strong noise.

Journal ArticleDOI
TL;DR: Some novel transient transition behaviors with different time scales are found in the memristor circuit, both theoretically and numerically.
Abstract: A simple memristor-based chaotic circuit with an active flux-controlled memristor characterized by a smooth continuous cubic nonlinearity is designed. The proposed chaotic circuit can generate a 2-scroll chaotic attractor on a finite time scale and has an equilibrium set with its stability dependent on the initial state of the memristor. The complex dynamics of the proposed chaotic circuit under different initial state of the memristor are investigated both theoretically and numerically. In particular, some novel transient transition behaviors with different time scales are found in the memristor circuit. Experimental observations based on a universal circuit implementation platform are conducted to partially verify the numerical simulation results.

Journal ArticleDOI
TL;DR: A modified possibilistic fuzzy c-means clustering algorithm is presented for fuzzy segmentation of magnetic resonance (MR) images that have been corrupted by intensity inhomogeneities and noise, capable of utilizing local contextual information to impose local spatial continuity, thus allowing the suppression of noise and helping to resolve classification ambiguity.

Journal ArticleDOI
TL;DR: The results indicate that the CdS/BCF hybrid nanofibers are promising candidate as robust visible light responsive photocatalysts.

Journal ArticleDOI
TL;DR: By using the SPCE array and the universal nanoprobe, the immunoassay system shows promising applications for in-field and point-of-care test in clinical diagnostics and demonstrates simultaneous detection of two protein biomarkers.

Journal ArticleDOI
TL;DR: A series of polyethylene glycol (PEG) functionalized graphene sheet hybrid materials (FGHMs) synthesized via ester linkages significantly improves the thermal stability of the bulk polymers and suggests their great potential as novel nanofillers in industry.
Abstract: A series of polyethylene glycol (PEG) functionalized graphene sheet hybrid materials (FGHMs) have been successfully synthesized via ester linkages. Interestingly, our products can be dispersed in both polar/protic solvents and nonpolar/nonprotic ones, which differ significantly from previously reported systems and are of great value in the wide-spread application of these "carbon nanosheet" based materials by solution-phase processing. Furthermore, the addition of PEG-modified carbon nanosheets as nanofillers significantly improves the thermal stability of the bulk polymers. In our case, an increase of 35 K in thermal stability can be obtained for PEG4000 after filling with as low as 1 wt % of the PEG modified carbon sheets, suggesting their great potential as novel nanofillers in industry.

Journal ArticleDOI
TL;DR: In this article, multiferroic BiFeO 3 nanoparticles were prepared by a sol-gel rapid calcination technique with average diameter of 35nm with narrow size distribution, indicating their potential application as visible-light-response photocatalyst.

Journal ArticleDOI
TL;DR: In this article, the effect of reduction ratio and rolling temperature on the microstructure, bonding strength and thickness ratio of a hot roll bonding method on the composite was studied. And the authors showed that the bonding strength of the composite decreased with reduction ratio, due to an increase in the grain size and diffusion layer width.
Abstract: In this study, 7075 Al/AZ31B Mg/7075 Al laminated composites were prepared by hot roll bonding method. Microstructure and bonding strength of the experimental laminated composites, and thickness ratio of the constituent layers after hot rolling were evaluated. Effects of reduction ratio and rolling temperature on the microstructure, bonding strength and thickness ratio were also studied. Dynamic recrystallization microstructures were observed in the composite. The bonding strength decreased with reduction ratio and rolling temperature due to the increase in the grain size and diffusion layer width with the reduction ratio and rolling temperature. The maximal bonding strength of the experimental laminated composite was 66 MPa. The thickness fraction of the Mg alloy plate after hot rolling decreased with the reduction ratio and rolling temperature.

Journal ArticleDOI
TL;DR: Compared with MnO(2) nanolamellas, the nanocomposite prepared with a reaction time of 3 h reveals better electrochemical properties as a supercapacitor electrode material.
Abstract: 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.

Journal ArticleDOI
TL;DR: An efficient and robust passive authentication method that uses the circle block and the Hu moments to detect and locate the duplicate regions with rotation that is robust not only to noise contamination, blurring and JPEG compression, but also to the rotation.

Journal ArticleDOI
TL;DR: It is shown that in the incomplete information system, the smaller upper approximations can be obtained by neighborhood system based rough sets than by the methods in [Y.Y. Leung], and a new knowledge operation is discussed in the neighborhood system, from which more knowledge can be derived from the initial neighborhood system.
Abstract: Neighborhood system formalized the ancient intuition, infinitesimals, which led to the invention of calculus, topology and non-standard analysis. In this paper, the neighborhood system is researched from the view point of knowledge engineering and then each neighborhood is considered as a basic unit with knowledge. By using these knowledge in neighborhood system, the rough approximations and the corresponding properties are discussed. It is shown that in the incomplete information system, the smaller upper approximations can be obtained by neighborhood system based rough sets than by the methods in [Y. Leung, D.Y. Li, Maximal consistent block technique for rule acquisition in incomplete information systems, Information Sciences 115 (2003) 85-106] and [Y. Leung, W.Z. Wu, W.X. Zhang, Knowledge acquisition in incomplete information systems: a rough set approach, European Journal of Operational Research 168 (2006) 164-180]. Furthermore, a new knowledge operation is discussed in the neighborhood system, from which more knowledge can be derived from the initial neighborhood system. By such operations, the regions of lower and upper approximations are further expanded and narrowed, respectively. Some numerical examples are employed to substantiate the conceptual arguments.

Journal ArticleDOI
TL;DR: In this article, the binding energies of 1-OH-BTA and 1-hydroxybenzotriazole with cuprous oxide (Cu 2 O) crystal have been simulated by molecular dynamics in water solution.

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a new space of functions of fractional-order bounded variation called the BV α space by using the Grunwald-Letnikov definition of fractiona-order derivative, which can improve the peak signal to noise ratio of image, preserve textures and eliminate the staircase effect.

Journal ArticleDOI
TL;DR: Hexaphenylbenzene-based porous organic polymers are prepared smoothly through palladium-catalyzed C-C coupling polymerization as mentioned in this paper, and the Brunauer-Emmett-Teller specific surface area for these polymers varies between 742 and 1148 m2 g-1.13 bar and 77 K.
Abstract: Hexaphenylbenzene-based porous organic polymers are prepared smoothly through palladium-catalyzed C–C coupling polymerization. According to the obtained nitrogen physisorption isotherms, the Brunauer–Emmett–Teller specific surface area for these polymers varies between 742 and 1148 m2 g–1. Gravimetric hydrogen adsorption isotherms show that the adsorption capacity for hydrogen is up to 1.5 wt % at 1.13 bar and 77 K. Thanks to the propeller-like structure, unique electronic feature, and efficient preparation, hexaphenylbenzene can be taken as a promising building block for designing porous polymers with special properties.

Journal ArticleDOI
TL;DR: This work provides a simple and "green" method for the synthesis of graphene oxide sheets decorated by silver nanoprisms in aqueous solution with promising antibacterial property.

Journal ArticleDOI
TL;DR: In this paper, a Lyapunov-Krasovskii formulation of scaled small gain problem for systems described by coupled differential-difference equations is presented, where a discretization may be applied to reduce the conditions into linear matrix inequalities.
Abstract: This article presents a Lyapunov–Krasovskii formulation of scaled small gain problem for systems described by coupled differential-difference equations. This problem includes H∞ problem with block-diagonal uncertainty as a special case. A discretization may be applied to reduce the conditions into linear matrix inequalities. As an application, the stability problem of systems with time-varying delays is transformed into the scaled small gain problem through a process of either one-term approximation or two-term approximation. The cases of time-varying delays with and without derivative upper-bound are compared. Finally, it is shown that similar conditions can also be obtained by a direct Lyapunov–Krasovskii functional method for coupled differential-functional equations. Numerical examples are presented to illustrate the effectiveness of the method in tackling systems with time-varying delays. Copyright © 2010 John Wiley & Sons, Ltd.