Showing papers by "City University of Hong Kong published in 2006"
TL;DR: A survey on recent developments (or state of the art) of analysis and design of model based fuzzy control systems based on the so-called Takagi-Sugeno fuzzy models or fuzzy dynamic models.
Abstract: Fuzzy logic control was originally introduced and developed as a model free control design approach. However, it unfortunately suffers from criticism of lacking of systematic stability analysis and controller design though it has a great success in industry applications. In the past ten years or so, prevailing research efforts on fuzzy logic control have been devoted to model-based fuzzy control systems that guarantee not only stability but also performance of closed-loop fuzzy control systems. This paper presents a survey on recent developments (or state of the art) of analysis and design of model based fuzzy control systems. Attention will be focused on stability analysis and controller design based on the so-called Takagi-Sugeno fuzzy models or fuzzy dynamic models. Perspectives of model based fuzzy control in future are also discussed
1,575 citations
TL;DR: In this paper, a review of the processing, structure, and mechanical properties of polymer nanocomposites reinforced with respective layered silicates, ceramic nanoparticles and carbon nanotubes is presented.
Abstract: Recently, polymer nanocomposites reinforced with lower volume fraction of nanoceramics and carbon nanotubes have attracted steadily growing interest due to their peculiar and fascinating properties as well as their unique applications in commercial sectors. The incorporation of nanoceramics such as layered silicate clays, calcium carbonate or silica nanoparticles arranged on the nanometer scale with a high aspect ratio and/or an extremely large surface area into polymers improves their mechanical performances significantly. The properties of nanocomposites depend greatly on the chemistry of polymer matrices, nature of nanofillers, and the way in which they are prepared. The uniform dispersion of nanofillers in the polymer matrices is a general prerequisite for achieving desired mechanical and physical characteristics. In this review article, current development on the processing, structure, and mechanical properties of polymer nanocomposites reinforced with respective layered silicates, ceramic nanoparticles and carbon nanotubes will be addressed. Particular attention is paid on the structure–property relationship of such novel high-performance polymer nanocomposites.
1,346 citations
TL;DR: In this paper, the structures of various types of amorphous carbon films and common characterization techniques are described, which can be classified as polymer-like, diamond-like or graphite-like based on the main binding framework.
1,004 citations
15 Aug 2006
TL;DR: An online deterministic algorithm named BAR is presented and it is proved that it is 4.56-competitive, which improves the previous algorithm of Kim and Chwa which was shown to be 5-competitive by Chan et al.
Abstract: We study an on-line broadcast scheduling problem in which requests have deadlines, and the objective is to maximize the weighted throughput, i.e., the weighted total length of the satisfied requests. For the case where all requested pages have the same length, we present an online deterministic algorithm named BAR and prove that it is 4.56-competitive. This improves the previous algorithm of Kim and Chwa [11] which is shown to be 5-competitive by Chan et al. [4]. In the case that pages may have different lengths, we prove a lower bound of Ω(Δ/logΔ) on the competitive ratio where Δ is the ratio of maximum to minimum page lengths. This improves upon the previous $\sqrt{\Delta}$ lower bound in [11,4] and is much closer to the current upper bound of ($\Delta+2\sqrt{\Delta}+2$) in [7]. Furthermore, for small values of Δ we give better lower bounds.
669 citations
27 Jun 2006
TL;DR: Wang et al. as discussed by the authors presented a new generalization framework based on the concept of personalized anonymity, which performs the minimum generalization for satisfying everybody's requirements, and thus retains the largest amount of information from the microdata.
Abstract: We study generalization for preserving privacy in publication of sensitive data. The existing methods focus on a universal approach that exerts the same amount of preservation for all persons, with-out catering for their concrete needs. The consequence is that we may be offering insufficient protection to a subset of people, while applying excessive privacy control to another subset. Motivated by this, we present a new generalization framework based on the concept of personalized anonymity. Our technique performs the minimum generalization for satisfying everybody's requirements, and thus, retains the largest amount of information from the microdata. We carry out a careful theoretical study that leads to valuable insight into the behavior of alternative solutions. In particular, our analysis mathematically reveals the circumstances where the previous work fails to protect privacy, and establishes the superiority of the proposed solutions. The theoretical findings are verified with extensive experiments.
662 citations
TL;DR: In this article, a novel strategy for preparing large-area oriented silicon nanowire arrays on silicon substrates at near room temperature by localized chemical etching is presented, which is based on metal-induced (either by Ag or Au) excessive local oxidation and dissolution of a silicon substrate in an aqueous fluoride solution.
Abstract: A novel strategy for preparing large-area, oriented silicon nanowire (SiNW) arrays on silicon substrates at near room temperature by localized chemical etching is presented. The strategy is based on metal-induced (either by Ag or Au) excessive local oxidation and dissolution of a silicon substrate in an aqueous fluoride solution. The density and size of the as-prepared SiNWs depend on the distribution of the patterned metal particles on the silicon surface. High-density metal particles facilitate the formation of silicon nanowires. Well-separated, straight nanoholes are dug along the Si block when metal particles are well dispersed with a large space between them. The etching technique is weakly dependent on the orientation and doping type of the silicon wafer. Therefore, SiNWs with desired axial crystallographic orientations and doping characteristics are readily obtained. Detailed scanning electron microscopy observations reveal the formation process of the silicon nanowires, and a reasonable mechanism is proposed on the basis of the electrochemistry of silicon and the experimental results.
650 citations
21 Oct 2006
TL;DR: In this article, it was shown that the problem of finding a Nash equilibrium in a two-player game is PPAD-complete, and it has been proven so for games among three or more players recently.
Abstract: Even though many people thought the problem of finding Nash equilibria is hard in general, and it has been proven so for games among three or more players recently, it's not clear whether the two-player case can be shown in the same class of PPAD-complete problems. We prove that the problem of finding a Nash equilibrium in a two-player game is PPAD-complete
633 citations
TL;DR: In this paper, the authors examine a sample of connected transactions between Hong Kong listed companies and their controlling shareholders and find limited evidence that firms undertaking connected transactions trade at discounted valuations prior to the expropriation.
606 citations
TL;DR: CdS nanoribbon has the response speed substantively faster than those ever reported for conventional film and bulk CdS materials and the size ofnanoribbons has a significant influence on the responsespeed with smaller Cd S nanorIBbons showing higher response speed.
Abstract: The photoconductive characteristics of CdS single nanoribbons were investigated. The device characteristics, including spectral response, light intensity response, and time response, were studied systematically. It is found that CdS nanoribbon has the response speed substantively faster than those ever reported for conventional film and bulk CdS materials and the size of nanoribbons has a significant influence on the response speed with smaller CdS nanoribbons showing higher response speed. The high photosensitivity and high photoresponse speed are attributable to the large surface-to-volume ratio and high single-crystal quality of CdS nanoribbons and the reduction of recombination barrier in nanostructures. Measurements in a different atmosphere demonstrate that the absorption of ambient gas (mainly oxygen) can significantly change the photosensitivity of CdS nanoribbons through trapping electrons from the nanoribbons.
547 citations
TL;DR: This article provides an in-depth review on the applications of microfluidic devices for cell-based assays in recent years, including micro cytometer, micro fluidic chemical cytometry, biochemical sensing chip, and whole cell sensing chip.
540 citations
TL;DR: A residual test (RT) is proposed that can simultaneously determine the number of line-of-sight (LOS) BS and identify them and then, localization can proceed with only those LOS BS.
Abstract: Three or more base stations (BS) making time-of-arrival measurements of a signal from a mobile station (MS) can locate the MS. However, when some of the measurements are from non-line-of-sight (NLOS) paths, the location errors can be very large. This paper proposes a residual test (RT) that can simultaneously determine the number of line-of-sight (LOS) BS and identify them. Then, localization can proceed with only those LOS BS. The RT works on the principle that when all measurements are LOS, the normalized residuals have a central Chi-Square distribution, versus a noncentral distribution when there is NLOS. The residuals are the squared differences between the estimates and the true position. Normalization by their variances gives a unity variance to the resultant random variables. In simulation studies, for the chosen geometry and NLOS and measurement noise errors, the RT can determine the correct number of LOS-BS over 90% of the time. For four or more BS, where there are at least three LOS-BS, the estimator has variances that are near the Cramer--Rao lower bound.
TL;DR: Investigation of the effectiveness of various trust-building strategies to influence actual buying behavior in online shopping environments shows that endorsements by similar (local, nonforeign) peers, but not by dissimilar (foreign) peer peers, were effective means of developing trust among first-time visitors to online stores.
Abstract: This research investigates the effectiveness of various trust-building strategies to influence actual buying behavior in online shopping environments, particularly for first-time visitors to an Internet store that does not have an established reputation. Drawing from the literature on trust, we developed a model of how trust-building strategies could affect trust and the consequences of trust. We investigated two trust-building strategies: portal association (based on reputation categorization and trust transference) and satisfied customer endorsements (based on unit grouping, reputation categorization, and trust transference).
A series of two studies was conducted at a large public university in Hong Kong. The first study employed a laboratory experiment to test the model in an online bookstore environment, using a real task that involves actual book purchases. Of the two strategies investigated, satisfied customer endorsement by similar peers, but not portal association, was found to increase consumers' trusting beliefs about the store. This, in turn, positively influenced consumers' attitudes toward the store and their willingness to buy from the store, which ultimately led to actual buying behaviors. To gather further insights on the two Web strategies investigated, a second study was conducted using a questionnaire survey approach. Overall, the findings corroborated those in the first study. Specifically, it shows that endorsements by similar (local, nonforeign) peers, but not by dissimilar (foreign) peers, were effective means of developing trust among first-time visitors to online stores.
TL;DR: Over the last two decades, theoretical design and circuit implementation of various chaos generators have been a focal subject of increasing interest due to their promising applications in various ...
Abstract: Over the last two decades, theoretical design and circuit implementation of various chaos generators have been a focal subject of increasing interest due to their promising applications in various ...
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22 Feb 2006TL;DR: In this paper, the authors consider the problem of defining an immersion defined on an open set in R3 with a prescribed metric tensor, and prove the existence and uniqueness of a surface as a function of its fundamental forms.
Abstract: Preface Chapter 1. Three-dimensional differential geometry: 1.1. Curvilinear coordinates, 1.2. Metric tensor, 1.3. Volume, areas, and lengths in curvilinear coordinates, 1.4. Covariant derivatives of a vector field, 1.5. Necessary conditions satisfied by the metric tensor the Riemann curvature tensor, 1.6. Existence of an immersion defined on an open set in R3 with a prescribed metric tensor, 1.7. Uniqueness up to isometries of immersions with the same metric tensor, 1.8. Continuity of an immersion as a function of its metric tensor Chapter 2. Differential geometry of surfaces: 2.1. Curvilinear coordinates on a surface, 2.2. First fundamental form, 2.3. Areas and lengths on a surface, 2.4. Second fundamental form curvature on a surface, 2.5. Principal curvatures Gaussian curvature, 2.6. Covariant derivatives of a vector field defined on a surface the Gauss and Weingarten formulas, 2.7. Necessary conditions satisfied by the first and second fundamental forms: the Gauss and Codazzi-Mainardi equations Gauss' theorema egregium, 2.8. Existence of a surface with prescribed first and second fundamental forms, 2.9. Uniqueness up to proper isometries of surfaces with the same fundamental forms, 2.10.Continuity of a surface as a function of its fundamental forms Chapter 3. Applications to three-dimensional elasticity in curvilinear coordinates: 3.1. The equations of nonlinear elasticity in Cartesian coordinates, 3.2. Principle of virtual work in curvilinear coordinates, 3.3. Equations of equilibrium in curvilinear coordinates covariant derivatives of a tensor field, 3.4. Constitutive equation in curvilinear coordinates, 3.5. The equations of nonlinear elasticity in curvilinear coordinates, 3.6. The equations of linearized elasticity in curvilinear coordinates, 3.7. A fundamental lemma of J.L. Lions, 3.8. Korn's inequalities in curvilinear coordinates, 3.9. Existence and uniqueness theorems in linearizedelasticity in curvilinear coordinates Chapter 4. Applications to shell theory: 4.1. The nonlinear Koiter shell equations, 4.2. The linear Koiter shell equations, 4.3. Korn's inequality on a surface, 4.4. Existence and uniqueness theorems for the linear Koiter shell equations covariant derivatives of a tensor field defined on a surface, 4.5. A brief review of linear shell theories References Index.
TL;DR: In this article, an adaptive neural control of a completely non-affine pure-feedback system using RBF neural networks is presented by combining adaptive neural design with the backstepping method, input-to-state stability (ISS) analysis and the small-gain theorem.
TL;DR: In this article, Riahi-Belkaoiu et al. investigated tax evasion on a cross-country basis and found that complexity is the most important determinant of tax evasion, followed by education, income source, fairness and tax morale.
TL;DR: In this paper, the viability of the technology on construction waste recycling and their viability is reviewed. And the viable technology of the construction material recycling should be provided an easy reference for future applications.
Abstract: Environmental problems have been considered as a serious situation in the construction. Waste management is pressing harder with the alarming signal warning the industry. Reuse, recycling and reduce the wastes consider as the only methods to recover those waste generated; however, the implementations still have much room for improvement. This paper reviews the technology on construction waste recycling and their viability. Ten material recycling practices are studied, including: (i) asphalt, (ii) brick, (iii) concrete, (iv) ferrous metal, (v) glass, (vi) masonry, (vii) non-ferrous metal, (viii) paper and cardboard, (ix) plastic and (x) timber. The viable technology of the construction material recycling should be provided an easy reference for future applications.
01 Jul 2006
TL;DR: In this paper, the authors summarize the recent achievements in Asian dust storm research with an emphasis on dust climatology, modeling and satellite monitoring, including new dust models and techniques in satellite remote sensing and system integration.
Abstract: In arid and semi-arid area of Asia, dust storms occur frequently. Asian dust storms have a major impact on the air quality of the densely populated areas of China, Korea and Japan, and are important to the global dust cycle. In extreme cases, they result in the loss of human lives and disruptions of social and economic activities. In recent years, systematic research on Asian dust storms has been carried out. Much progress has been made in the development of integrated dust storm monitoring and modeling systems by making use of advanced numerical models, satellite remote sensing and GIS data. In this paper, we summarize the recent achievements in Asian dust storm research with an emphasis on dust climatology, modeling and satellite monitoring. The concept of integrated dust storm monitoring and modeling system is described and a summary of the developments in key research areas is given, including new dust models and techniques in satellite remote sensing and system integration. We then discuss the current research frontiers and the challenges for future studies.
TL;DR: In this article, the elastic buckling analysis of micro- and nano-rods/tubes based on Eringen's nonlocal elasticity theory and the Timoshenko beam theory is concerned.
Abstract: This paper is concerned with the elastic buckling analysis of micro- and nano-rods/tubes based on Eringen's nonlocal elasticity theory and the Timoshenko beam theory. In the former theory, the small scale effect is taken into consideration while the effect of transverse shear deformation is accounted for in the latter theory. The governing equations and the boundary conditions are derived using the principle of virtual work. Explicit expressions for the critical buckling loads are derived for axially loaded rods/tubes with various end conditions. These expressions account for a better representation of the buckling behaviour of micro- and nano-rods/tubes where small scale effect and transverse shear deformation effect are significant. By comparing it with the classical beam theories, the sensitivity of the small scale effect on the buckling loads may be observed.
21 Aug 2006
TL;DR: A survey of corporate wiki users indicated that corporate wikis appear to be sustainable, and users acknowledged making a variety of contributions, which suggests that they could be categorized as "synthesizers" and "adders".
Abstract: A survey of 168 corporate wiki users was conducted. Findings indicate that corporate wikis appear to be sustainable. Users stated three main types of benefits from corporate wikis: enhanced reputation, work made easier, and helping the organization to improve its processes. These benefits were seen as more likely when the wiki was used for tasks requiring novel solutions and the information posted was from credible sources. Users acknowledged making a variety of contributions, which suggests that they could be categorized as "synthesizers" and "adders". Synthesizers" frequency of contribution was affected more by their impact on other wiki users, while adders" contribution frequency was affected more by being able to accomplish their immediate work.
TL;DR: In this article, a metaheuristic simulation-optimization approach was proposed for the effective energy management of HVAC system, which can effectively handle the discrete, non-linear and highly constrained optimization problems.
TL;DR: An algorithm for estimating the mixing matrix that can be viewed as an extension of the DUET and the TIFROM methods is first developed and a necessary and sufficient condition for recoverability of a source vector is obtained.
Abstract: This paper discusses underdetermined (i.e., with more sources than sensors) blind source separation (BSS) using a two-stage sparse representation approach. The first challenging task of this approach is to estimate precisely the unknown mixing matrix. In this paper, an algorithm for estimating the mixing matrix that can be viewed as an extension of the DUET and the TIFROM methods is first developed. Standard clustering algorithms (e.g., K-means method) also can be used for estimating the mixing matrix if the sources are sufficiently sparse. Compared with the DUET, the TIFROM methods, and standard clustering algorithms, with the authors' proposed method, a broader class of problems can be solved, because the required key condition on sparsity of the sources can be considerably relaxed. The second task of the two-stage approach is to estimate the source matrix using a standard linear programming algorithm. Another main contribution of the work described in this paper is the development of a recoverability analysis. After extending the results in , a necessary and sufficient condition for recoverability of a source vector is obtained. Based on this condition and various types of source sparsity, several probability inequalities and probability estimates for the recoverability issue are established. Finally, simulation results that illustrate the effectiveness of the theoretical results are presented.
TL;DR: This paper presents the correct centroid formulae for fuzzy numbers and justify them from the viewpoint of analytical geometry and a numerical example demonstrates that Cheng's formULae can significantly alter the result of the ranking procedure.
TL;DR: Interestingly, it is found that the frequency of cooperation of the MBSG on a scale-free network peaks at a specific value of the payoff parameter, indicating that properly encouraging selfish behaviors can optimally enhance the cooperation.
Abstract: We present a memory-based snowdrift game (MBSG) taking place on networks. We found that, when a lattice is taken to be the underlying structure, the transition of spatial patterns at some critical values of the payoff parameter is observable for both four- and eight-neighbor lattices. The transition points as well as the styles of spatial patterns can be explained by local stability analysis. In sharp contrast to previously reported results, cooperation is promoted by the spatial structure in the MBSG. Interestingly, we found that the frequency of cooperation of the MBSG on a scale-free network peaks at a specific value of the payoff parameter. This phenomenon indicates that properly encouraging selfish behaviors can optimally enhance the cooperation. The memory effects of individuals are discussed in detail and some non-monotonous phenomena are observed on both lattices and scale-free networks. Our work may shed some new light on the study of evolutionary games over networks.
TL;DR: In this article, the authors presented several delay-dependent conditions for a general complex dynamical network model with coupling delays, which guarantee the synchronized states to be asymptotically stable.
TL;DR: In this paper, an aluminum-alloy flat-box type PVT collector was constructed, with its fin efficiency approaching unity, for natural circulation and for domestic water heating purpose, and the test results showed that a high final hot water temperature in the collector system can be achieved after a one-day exposure.
TL;DR: In this article, the authors reviewed several critical issues of MOS gate dielectrics in the nanometer range and suggested that the conventional oxide can be scaled down, in principle, to two atomic layers of about 7 A, but this is not practically feasible because of the non-scalabilities of interface, trap capture cross-section, leakage current, and the statistical parameters of fabrication processes.
TL;DR: The chaotic behaviors of the fractional-order Chen system are investigated and it is found that the lowest order for this system to have chaos is 0.3, which is the lowest-order chaotic system among all the found chaotic systems to date.
Abstract: In this paper we numerically investigate the chaotic behaviors of the fractional-order Chen system. A striking finding is that the lowest order for this system to have chaos is 0.3, which is the lowest-order chaotic system among all the found chaotic systems to date.
TL;DR: In this article, a utility-based grade match method is proposed to transform both numerical data and qualitative (fuzzy) assessment information of various formats into the fuzzy belief structure, leading to a fuzzy belief decision matrix.
TL;DR: In this article, the authors provide an overview of CSR practices in Asia, evaluate the usefulness of codes of conduct, review the benefits of using CSR in supply chains, and review obstacles for companies wishing to adopt goodCSR practices.
Abstract: This research provides an overview of CSR practices in Asia, evaluates the usefulness of codes of conduct, reviews the benefits of CSR in supply chains and reviews obstacles for companies wishing to adopt good CSR practices. In order to achieve this, interviews were undertaken with CSR managers, factory managers and other experts, conducted in confidence and anonymously. Codes of conduct and associated inspections and audits are common practice but in most cases flawed. Labour issues and the rights of workers are generally seen as the most important aspect of CSR in the region. Benefits of CSR include risk reduction, staff recruitment and retention, cost savings and building good relationships with stakeholders. Obstacles include a lack of resources and skills, a lack of awareness of stakeholders' demands and inefficient production techniques. It is noted that larger firms are more able to overcome such obstacles, with clear adverse implications for smaller companies. Copyright © 2006 John Wiley & Sons, Ltd and ERP Environment.