Showing papers by "Southeast University published in 2009"
TL;DR: An experimental realization of a cloak design that conceals a perturbation on a flat conducting plane, under which an object can be hidden, and results indicate that this type of cloak should scale well toward optical wavelengths.
Abstract: The possibility of cloaking an object from detection by electromagnetic waves has recently become a topic of considerable interest. The design of a cloak uses transformation optics, in which a conformal coordinate transformation is applied to Maxwell's equations to obtain a spatially distributed set of constitutive parameters that define the cloak. Here, we present an experimental realization of a cloak design that conceals a perturbation on a flat conducting plane, under which an object can be hidden. To match the complex spatial distribution of the required constitutive parameters, we constructed a metamaterial consisting of thousands of elements, the geometry of each element determined by an automated design process. The ground-plane cloak can be realized with the use of nonresonant metamaterial elements, resulting in a structure having a broad operational bandwidth (covering the range of 13 to 16 gigahertz in our experiment) and exhibiting extremely low loss. Our experimental results indicate that this type of cloak should scale well toward optical wavelengths.
1,405 citations
TL;DR: This work proposes a new algorithm called PCA based conditional GCM, which achieves greater accuracy in detecting network connectivity than the commonly used pairwise Granger causality method and greatly reduces the computational cost relative to the use of individual voxel time series.
Abstract: Identifying directional influences in anatomical and functional circuits presents one of the greatest challenges for understanding neural computations in the brain. Granger causality mapping (GCM) derived from vector autoregressive models of data has been employed for this purpose, revealing complex temporal and spatial dynamics underlying cognitive processes. However, the traditional GCM methods are computationally expensive, as signals from thousands of voxels within selected regions of interest (ROIs) are individually processed, and being based on pairwise Granger causality, they lack the ability to distinguish direct from indirect connectivity among brain regions. In this work a new algorithm called PCA based conditional GCM is proposed to overcome these problems. The algorithm implements the following two procedures: (i) dimensionality reduction in ROIs of interest with principle component analysis (PCA), and (ii) estimation of the direct causal influences in local brain networks, using conditional Granger causality. Our results show that the proposed method achieves greater accuracy in detecting network connectivity than the commonly used pairwise Granger causality method. Furthermore, the use of PCA components in conjunction with conditional GCM greatly reduces the computational cost relative to the use of individual voxel time series.
960 citations
TL;DR: A comprehensive assessment on oxyfuel combustion in a pilot-scale oxyfuel furnace, modifying the design criterion for an oxy retrofit by matching heat transfer, a new 4-grey gas model which accurately predicts emissivity of the gases in oxy-fired furnaces has been developed for furnace modelling, the first measurements of coal reactivity comparisons in air and oxyfuel at laboratory and pilot scale; and predictions of observed delays in flame ignition in oxyfiring as discussed by the authors.
Abstract: Oxyfuel combustion is seen as one of the major options for CO2 capture for future clean coal technologies. The paper provides an overview on research activities and technology development through a fundamental research underpinning the Australia/Japan Oxyfuel Feasibility Project. Studies on oxyfuel combustion on a pilot-scale furnace and a laboratory scale drop tube furnace are presented and compared with computational fluid dynamics (CFD) predictions. The research has made several contributions to current knowledge, including; comprehensive assessment on oxyfuel combustion in a pilot-scale oxyfuel furnace, modifying the design criterion for an oxy retrofit by matching heat transfer, a new 4-grey gas model which accurately predicts emissivity of the gases in oxy-fired furnaces has been developed for furnace modelling, the first measurements of coal reactivity comparisons in air and oxyfuel at laboratory and pilot-scale; and predictions of observed delays in flame ignition in oxy-firing.
760 citations
TL;DR: Immunohistochemical analysis of 303 clinical specimens from three independent cohorts of lung cancer patients and controls show that expression of ALDH1 is positively correlated with the stage and grade of lung tumors and related to a poor prognosis for the patients with early-stage lung cancer.
Abstract: Tumor contains small population of cancer stem cells (CSC) that are responsible for its maintenance and relapse. Analysis of these CSCs may lead to effective prognostic and therapeutic strategies for the treatment of cancer patients. We report here the identification of CSCs from human lung cancer cells using Aldefluor assay followed by fluorescence-activated cell sorting analysis. Isolated cancer cells with relatively high aldehyde dehydrogenase 1 (ALDH1) activity display in vitro features of CSCs, including capacities for proliferation, self-renewal, and differentiation, resistance to chemotherapy, and expressing CSC surface marker CD133. In vivo experiments show that the ALDH1-positive cells could generate tumors that recapitulate the heterogeneity of the parental cancer cells. Immunohistochemical analysis of 303 clinical specimens from three independent cohorts of lung cancer patients and controls show that expression of ALDH1 is positively correlated with the stage and grade of lung tumors and related to a poor prognosis for the patients with early-stage lung cancer. ALDH1 is therefore a lung tumor stem cell-associated marker. These findings offer an important new tool for the study of lung CSCs and provide a potential prognostic factor and therapeutic target for treatment of the patients with lung cancer. (Mol Cancer Res 2009;7(3):330–8)
743 citations
TL;DR: Silver-impregnated chitosan films with silver showed both fast and long-lasting antibacterial effectiveness against Escherichia coli.
582 citations
TL;DR: Simulation and experimental results show that the proposed adaptive control scheme for the permanent-magnet synchronous motor speed-regulation system achieves a better speed response in the presence of inertia variations.
Abstract: Considering the variations of inertia in real applications, an adaptive control scheme for the permanent-magnet synchronous motor speed-regulation system is proposed in this paper. First, a composite control method, i.e., the extended-state-observer (ESO)-based control method, is employed to ensure the performance of the closed-loop system. The ESO can estimate both the states and the disturbances simultaneously so that the composite speed controller can have a corresponding part to compensate for the disturbances. Then, considering the case of variations of load inertia, an adaptive control scheme is developed by analyzing the control performance relationship between the feedforward compensation gain and the system inertia. By using inertia identification techniques, a fuzzy-inferencer-based supervisor is designed to automatically tune the feedforward compensation gain according to the identified inertia. Simulation and experimental results both show that the proposed method achieves a better speed response in the presence of inertia variations.
566 citations
TL;DR: It was indicated that the collected liquid in the second condenser with HZSM-5 had high qualities and might be used as transport oil.
429 citations
TL;DR: While the FRN may function as a general mechanism that evaluates whether the outcome is consistent or inconsistent with expectation, the P300 is sensitive to a later, top-down controlled process of outcome evaluation, into which factors related to the allocation of attentional resources come to play.
417 citations
TL;DR: An improved bacterial chemotaxis optimization (IBCO) is proposed, which is then integrated into the back propagation (BP) artificial neural network to develop an efficient forecasting model for prediction of various stock indices.
Abstract: The paper proposed an improved bacterial chemotaxis optimization (IBCO), which is then integrated into the back propagation (BP) artificial neural network to develop an efficient forecasting model for prediction of various stock indices. Experiments show its better performance than other methods in learning ability and generalization.
414 citations
TL;DR: In this paper, the impact of supply disruption risks on the choice between the famous single and dual sourcing methods in a two-stage supply chain with a non-stationary and price-sensitive demand is evaluated.
Abstract: The focus of this paper is placed on evaluating the impacts of supply disruption risks on the choice between the famous single and dual sourcing methods in a two-stage supply chain with a non-stationary and price-sensitive demand. The expected profit functions of the two sourcing modes in the presence of supply chain disruption risks are first obtained, and then compared so that the critical values of the key factors affecting the final choice are identified. Finally, the sensitivity of the buyer's expected profit to various input factors is examined through numerical examples, which provide guidelines for how to use each sourcing method.
369 citations
TL;DR: It is proved that in Markov-switching topologies, the network is mean square consentable under linear consensus protocol if and only if the union of graphs in the switching topology set has globally reachable nodes.
TL;DR: A unified LMI approach is developed to solve the stability analysis and synchronization problems of the class of neural networks under investigation, where the LMIs can be easily solved by using the available Matlab LMI toolbox.
Abstract: In this paper, we introduce a new class of discrete-time neural networks (DNNs) with Markovian jumping parameters as well as mode-dependent mixed time delays (both discrete and distributed time delays). Specifically, the parameters of the DNNs are subject to the switching from one to another at different times according to a Markov chain, and the mixed time delays consist of both discrete and distributed delays that are dependent on the Markovian jumping mode. We first deal with the stability analysis problem of the addressed neural networks. A special inequality is developed to account for the mixed time delays in the discrete-time setting, and a novel Lyapunov-Krasovskii functional is put forward to reflect the mode-dependent time delays. Sufficient conditions are established in terms of linear matrix inequalities (LMIs) that guarantee the stochastic stability. We then turn to the synchronization problem among an array of identical coupled Markovian jumping neural networks with mixed mode-dependent time delays. By utilizing the Lyapunov stability theory and the Kronecker product, it is shown that the addressed synchronization problem is solvable if several LMIs are feasible. Hence, different from the commonly used matrix norm theories (such as the M-matrix method), a unified LMI approach is developed to solve the stability analysis and synchronization problems of the class of neural networks under investigation, where the LMIs can be easily solved by using the available Matlab LMI toolbox. Two numerical examples are presented to illustrate the usefulness and effectiveness of the main results obtained.
TL;DR: Results indicate that nonneutral convergent molecular evolution in mitochondria can occur at a scale and intensity far beyond what has been documented previously, and they highlight the vulnerability of standard phylogenetic methods to the presence of non neutral convergent sequence evolution.
Abstract: Documented cases of convergent molecular evolution due to selection are fairly unusual, and examples to date have involved only a few amino acid positions. However, because convergence mimics shared ancestry and is not accommodated by current phylogenetic methods, it can strongly mislead phylogenetic inference when it does occur. Here, we present a case of extensive convergent molecular evolution between snake and agamid lizard mitochondrial genomes that overcomes an otherwise strong phylogenetic signal. Evidence from morphology, nuclear genes, and most sites in the mitochondrial genome support one phylogenetic tree, but a subset of mostly amino acid-altering substitutions (primarily at the first and second codon positions) across multiple mitochondrial genes strongly supports a radically different phylogeny. The relevant sites generally evolved slowly but converged between ancient lineages of snakes and agamids. We estimate that approximately 44 of 113 predicted convergent changes distributed across all 13 mitochondrial protein-coding genes are expected to have arisen from nonneutral causes-a remarkably large number. Combined with strong previous evidence for adaptive evolution in snake mitochondrial proteins, it is likely that much of this convergent evolution was driven by adaptation. These results indicate that nonneutral convergent molecular evolution in mitochondria can occur at a scale and intensity far beyond what has been documented previously, and they highlight the vulnerability of standard phylogenetic methods to the presence of nonneutral convergent sequence evolution.
TL;DR: In this paper, the performance objectives and key performance indicators (KPIs) are identified to improve process and performance management in PPPs, and the relative significance and difference of performance objectives for different stakeholders are presented based on a structured questionnaire survey.
Abstract: Public–private partnerships (PPPs) have been applied widely in the global construction market. During the life cycle of PPP projects, their performance could be affected by a number of factors and their interactions, which might cause the inefficiency and ineffectiveness of the projects. Previous researches on PPPs mainly concentrated on the procurement, success measurement and risk management of PPPs, but paid little attention to the process factors that can strongly influence the performance of PPPs. In order to improve process and performance management in PPPs, the performance objectives and key performance indicators (KPIs) are identified to improve the partnership outcomes. Based on the goal‐setting theory, 15 performance objectives are selected. The relative significance and difference of performance objectives for different stakeholders are presented based on a structured questionnaire survey. The survey results show that all identified objectives are important. In spite of stakeholders' common op...
TL;DR: The structural blue color of a Morpho butterfly originates from the diffraction of light and interference effects due to the presence of the microstructures on the wing of the butterfly, and a useful technique to prepare structural color films in colloidal solution is a "lifting" method, which allows to quickly fabricate brilliant colloidal crystal films.
Abstract: The structural blue color of a Morpho butterfly originates from the diffraction of light and interference effects due to the presence of the microstructures on the wing of the butterfly. Structural color on the surface of a damselfish reversibly changes between green and blue. Inspired by these creatures, we have been trying to prepare high-quality and functional structural color films. We describe our efforts in this Account. A useful technique to prepare such structural color films in colloidal solution is a “lifting” method, which allows us to quickly fabricate brilliant colloidal crystal films. The thicknesses of the films can be controlled by precisely adjusting the particle concentration and the lifting speed. Moreover, in order to prepare a complicated structure, we have used template methods. Indeed, we have successfully prepared the inverse structure of the wing of a Morpho butterfly with this technique. Initially, however, our structural color films had a whitish appearance due to the scattering...
TL;DR: A similarity measure that takes into account not only a pure distance between intuitionistic fuzzy sets but also examines if the compared values are more similar or more dissimilar to each other is developed.
Abstract: Szmidt and Kacprzyk (Lecture Notes in Artificial Intelligence 3070:388---393, 2004a) introduced a similarity measure, which takes into account not only a pure distance between intuitionistic fuzzy sets but also examines if the compared values are more similar or more dissimilar to each other. By analyzing this similarity measure, we find it somewhat inconvenient in some cases, and thus we develop a new similarity measure between intuitionistic fuzzy sets. Then we apply the developed similarity measure for consensus analysis in group decision making based on intuitionistic fuzzy preference relations, and finally further extend it to the interval-valued intuitionistic fuzzy set theory.
TL;DR: This paper investigates the synchronization problem for a class of complex delayed dynamical networks by pinning periodically intermittent control using the Lyapunov stability theory and periodically intermittent Control method.
Abstract: This paper investigates the synchronization problem for a class of complex delayed dynamical networks by pinning periodically intermittent control. Based on a general model of complex delayed dynamical networks, using the Lyapunov stability theory and periodically intermittent control method, some simple criteria are derived for the synchronization of such dynamical networks. Furthermore, a Barabasi–Albert network consisting of coupled delayed Chua oscillators is finally given as an example to verify the effectiveness of the theoretical results.
TL;DR: Students' perceptions of teacher support and student-student support were positively associated with adolescents' self-esteem and grade point average but negatively associated with depressive symptoms for both Chinese and American adolescents.
Abstract: This study explored students' perceptions of 3 dimensions of school climate (teacher support, student-student support, and opportunities for autonomy in the classroom) and the associations between these dimensions and adolescent psychological and academic adjustment in China and the United States. Data were drawn from 2 studies involving 706 middle school students (M = 12.26) from Nanjing, China, and 709 middle school students (M = 12.36) from New York City. Findings revealed that students in China perceived higher levels of teacher support, student-student support, and opportunities for autonomy in the classroom than students in the United States. Furthermore, students' perceptions of teacher support and student-student support were positively associated with adolescents' self-esteem and grade point average but negatively associated with depressive symptoms for both Chinese and American adolescents.
TL;DR: The consensus problem of second-order multi-agent systems with diverse input delays is investigated, and a bound of the largest singular value of the perturbation matrix is obtained as the robust consensus condition.
TL;DR: In this paper, the self-healing behavior of a series of pre-cracked fiber reinforced strain hardening composites incorporating blast furnace slag and limestone powder with relatively high water/binder ratio is investigated, focusing on the recovery of its deflection capacity.
Abstract: The self-healing behavior of a series of pre-cracked fiber reinforced strain hardening cementitious composites incorporating blast furnace slag (BFS) and limestone powder (LP) with relatively high water/binder ratio is investigated in this paper, focusing on the recovery of its deflection capacity. Four-point bending tests are used to precrack the beam at 28 days. For specimens submerged in water the deflection capacity can recover about 65-105% from virgin specimens, which is significantly higher compared with specimens cured in air. Similar conclusion applies to the stiffness recovery in water cured specimens. The observations under ESEM and XEDS confirmed that the microcracks in the specimens submerged in water were healed with significant amount of calcium carbonate, very likely due to the continuous hydration of cementitious materials. The self-healing cementitious composites developed in this research can potentially reduce or even eliminate the maintenance needs of civil infrastructure, especially when repeatable high deformation capacity is desirable, e.g. bridge deck link slabs and jointless pavements. © 2009 Elsevier Ltd. All rights reserved.
TL;DR: The interaction between the SPIO-inclusion microbubbles and cells indicates that such microbubble construct can retain the acoustic property under the ultrasound exposure by controlling the SPio concentration in the shell.
TL;DR: It is suggested that the characteristics of resting-state functional connectivity could plausibly provide an early imaging biomarker for AD and the results of increased connectivity may support the compensatory-recruitment hypothesis.
TL;DR: In this paper, a hybrid excitation flux-switching (HEFS) motor is proposed, in which the airgap field can be easily controlled and is favorable for hybrid vehicles, and the preliminary topology, operation principle, design and static characteristics including phase flux-linkage, back-EMF waveforms under different excitations as well as cogging torque are evaluated based on finite element analysis.
Abstract: Flux-switching permanent magnet (FSPM) motor is a relatively novel brushless machine having magnets and concentrated windings in the stator instead of the conventional rotor-PM topology, which exhibits inherently sinusoidal PM flux-linkage, back-EMF waveforms and high torque capability. However, since the airgap field is produced by the stator-magnets alone, it is difficult to be regulated. Hence, a hybrid excitation method, i.e., by introducing a set of field windings into FSPM motor is employed. In this paper, a novel hybrid excitation flux-switching (HEFS) motor is proposed, in which the airgap field can be easily controlled and is favorable for hybrid vehicles. The preliminary topology, operation principle, design and static characteristics including phase flux-linkage, back-EMF waveforms under different excitations as well as cogging torque are evaluated based on finite element (FE) analysis. The results confirm the excellent field-regulation capability of a ldquoproof-of-principlerdquo HEFS motor.
TL;DR: This paper investigates cluster synchronization in an array of hybrid coupled neural networks with delay by constructing a special coupling matrix based on Lyapunov stability theory and the linear matrix inequality (LMI) technique.
TL;DR: In this paper, the exponential stochastic synchronization problem for coupled neural networks with noise perturbations was studied and several sufficient conditions were obtained to ensure exponential synchronization with or without coupling delays.
TL;DR: In this article, the effects of combustion environment, oxygen concentration, particle size and heating rate were considered and the differences of pulverized coal pyrolysis, combustion and gaseous compounds release under two environments were analyzed.
TL;DR: This strategy was successfully demonstrated as a simple, cost-effective, specific, and potent method to detect AFP in practical samples and possessed high sensitivity and reproducibility.
Abstract: A novel strategy for sensitive detection of biomarkers using horseradish peroxidase (HRP)-functionalized silica nanoparticles as the label is presented. The enzyme-functionalized silica nanoparticles were fabricated by coimmobilization of HRP and α-fetoprotein antibody (anti-AFP, the secondary antibody, Ab2), a model protein, onto the surface of SiO2 nanoparticles using γ-glycidoxypropyltrimethoxysilane (GPMS) as the linkage. Through “sandwiched” immunoreaction, the enzyme-functionalized silica nanoparticle labels were brought close to the surface of gold substrates, as confirmed by the scanning electron microscopy (SEM) images. Enhanced detection sensitivity was achieved where the large surface area of SiO2 nanoparticle carriers increased the amount of HRP bound per sandwiched immunoreaction. The electrochemical and chemiluminescence measurement showed 29.5- and 61-fold increases in detection signals, respectively, in comparison with the traditional sandwich immunoassay. The improved particle synthesis u...
TL;DR: The results showed that cell-labeling efficiency of the nanoparticles was dependent on the incubation time and nanoparticles’ concentration, and these new magneto-fluorescent nanoagents have demonstrated the potential for future medical use.
Abstract: Labeling of cells with nanoparticles for living detection is of interest to various biomedical applications. In this study, novel fluorescent/magnetic nanoparticles were prepared and used in high-efficient cellular imaging. The nanoparticles coated with the modified chitosan possessed a magnetic oxide core and a covalently attached fluorescent dye. We evaluated the feasibility and efficiency in labeling cancer cells (SMMC-7721) with the nanoparticles. The nanoparticles exhibited a high affinity to cells, which was demonstrated by flow cytometry and magnetic resonance imaging. The results showed that cell-labeling efficiency of the nanoparticles was dependent on the incubation time and nanoparticles’ concentration. The minimum detected number of labeled cells was around 104by using a clinical 1.5-T MRI imager. Fluorescence and transmission electron microscopy instruments were used to monitor the localization patterns of the magnetic nanoparticles in cells. These new magneto-fluorescent nanoagents have demonstrated the potential for future medical use.
TL;DR: In this paper, the authors used bacteria induced calcium carbonate precipitation as a novel and environmentally friendly approach to produce a protective layer on the surface of cement-based materials in the study, where physical and chemical properties of the obtained layer were examined.
TL;DR: This paper aims to design a state estimator to estimate the network states such that, for all admissible parameter uncertainties and time-varying delays, the dynamics of the estimation error is guaranteed to be globally exponentially stable in the mean square.
Abstract: This paper is concerned with the problem of state estimation for a class of discrete-time coupled uncertain stochastic complex networks with missing measurements and time-varying delay. The parameter uncertainties are assumed to be norm-bounded and enter into both the network state and the network output. The stochastic Brownian motions affect not only the coupling term of the network but also the overall network dynamics. The nonlinear terms that satisfy the usual Lipschitz conditions exist in both the state and measurement equations. Through available output measurements described by a binary switching sequence that obeys a conditional probability distribution, we aim to design a state estimator to estimate the network states such that, for all admissible parameter uncertainties and time-varying delays, the dynamics of the estimation error is guaranteed to be globally exponentially stable in the mean square. By employing the Lyapunov functional method combined with the stochastic analysis approach, several delay-dependent criteria are established that ensure the existence of the desired estimator gains, and then the explicit expression of such estimator gains is characterized in terms of the solution to certain linear matrix inequalities (LMIs). Two numerical examples are exploited to illustrate the effectiveness of the proposed estimator design schemes.