Showing papers by "University of Macau published in 1998"
TL;DR: In this article, the probability density function (PDF) and the mean up-crossing rate (MCR) of the stationary responses of nonlinear stochastic systems excited by white noise are analyzed based on the assumption that the PDF of the responses is approximated with an exponential function of a polynomial in the state variables.
Abstract: The probability density function (PDF) and the mean up-crossing rate (MCR) of the stationary responses of nonlinear stochastic systems excited by white noise is analyzed based on the assumption that the PDF of the responses is approximated with an exponential function of a polynomial in the state variables. Based upon the approximate PDF, a new technique is developed for the approximate PDF solution of Fokker–Planck–Kolmogorov equation, and consequently, the MCR of the system responses is analyzed. Numerical results showed that the approximate PDFs and MCRs approach to the exact ones as the degree of the polynomial increases.
65 citations
TL;DR: In this article, the probability density function (PDF) of the response of a non-linear stochastic system excited by white noise is assumed to be a linear superposition of basic functions.
Abstract: The probability density function (PDF) of the response of a non-linear stochastic system excited by white noise is assumed to be a linear superposition of basic functions. The Gaussian PDFs are used as the basic functions which coefficients are the reciprocal of the number of the basic functions. Gaussian closure method is a special case of the proposed method. Examples are given to show the application of the method to the systems with additive random excitations and those with both additive and multiplicative random excitations. The PDFs and moments obtained with the proposed method and conventional Gaussian closure method are compared with the exact ones. Numerical results showed some advantages of the proposed method over Gaussian closure method.
31 citations
TL;DR: In this paper, the probability distribution function (PDF) of a random variable Z is approximated with c·eQ(z), where Q(z) is a polynomial function and c is normalizing constant.
30 citations
Posted Content•
TL;DR: In this paper, the authors used experimental methods to examine client acceptance, auditor pricing and effort decisions for clients of varying risk under two legal rules, joint and several liability, and proportionate liability.
Abstract: This study uses experimental methods to examine client acceptance, auditor pricing and effort decisions for clients of varying risk under two legal rules, joint and several liability, and proportionate liability. We predict greater availability of audit services for high-risk clients, lower audit prices, and lower audit effort under proportionate liability relative to joint and several liability. Our experimental evidence does not strongly support predicted prices due to underpricing behavior, but prices do reflect risk differences across client groups for both liability regimes. The results also exhibit some support for the predictions that auditors select low effort for the lowest-risk clients, and a lower effort level under proportionate liability relative to joint and several liability for moderate risk clients. As predicted for the highest-risk clients, high effort is selected under proportionate liability, and there is some evidence of a substantial reduction in contracting under joint and several liability.
29 citations
TL;DR: In this paper, the effect of rare-earth La2O3 on laser-clad coatings has been studied and compared with those for coatings without the additive element.
Abstract: The effect of rare-earth La2O3 on laser-clad coatings has been studied. For this purpose, nickel-based alloy powders with different contents of La2O3 were laser-clad on to a steel substrate. The clad coatings were examined and tested for microstructural features, microhardness, inclusions and phase composition. The results are compared with those for coatings without La2O3. The comparison indicates that additions of La2O3 refine the microstructure of the clad, and the coating increases its microhardness. Moreover, the wear resistance and corrosion resistance of the clad coatings are also enhanced.
22 citations
TL;DR: In this article, the authors make the case for a "mixed economy" of public and private providers of schooling as a public good in Macau, thereby building on the existing extensive private provision, with attention still needing to be given to quality control and increased governmental support.
Abstract: For centuries Macau has experienced extended market principles for schooling, with very limited state intervention in education, and only a recent history of regarding schooling as a public good. This paper suggests that laissez‐faire market principles have failed to provide high quality schooling in Macau and that considerable state intervention is required to ensure that education develops as a public good in Macau. The case is made for a ‘mixed economy’ of public and private providers of schooling as a public good in Macau, thereby building on the existing extensive private provision that exists there, with attention still needing to be given to quality control and increased governmental support. A state‐regulated market might be more effective than a genuinely open market. The case of Macau is used to demonstrate that public goods and private services are neither polar opposites nor mutually exclusive. The greater involvement of the state in education in Macau, with the impending handback of ...
18 citations
TL;DR: In this paper, a three-layered feed-forward artificial neural network was used to predict the daily SO 2 concentration 5 days in advance, and the accuracy of the ANN model is within 14.45% and 13.71% for two testing periods, respectively.
17 citations
TL;DR: In this article, a program of theoretical and experimental investigations of the granular sulfur/lime packed bed autotrophic denitrification system was planned and completed, which evaluated the stoichiometric, kinetic and physical characteristics of the process.
16 citations
TL;DR: In this article, the authors argue that there are few theories in software engineering that can really be qualified scientific and they try to demonstrate it from an epistemology viewpoint, and they conclude that those who develop software are akin to artisans rather than engineers.
Abstract: In a recent conference, there was a panel session on whether Software Engineering is really engineering. The debate was interesting but inconclusive, not because the panelists disagreed on the state of the arts of software engineering, but on the definition of what is called engineering. Some thought that the aim of engineering is to build useful machines, and as far as we build machines we are engineers using engineering knowledge. So the question of the panel session was somehow ill-posed. For others, an engineering needs a scientific theory to help building machines, and when the theory cannot well guide practice, the engineering is still at the craft stage [1].I believe on the last definition: an engineering must have a scientific theory as foundation and this theory can be applied to build products. If we examine other engineering disciplines such as mechanical, electrical, or civil engineering in a modern sense, all these engineering disciplines have their theoretic foundation [2]. Therefore, anyone who builds products without theoretic knowledge, whatever the expertise he may have, can only be called craftsman or artist, not engineer.In this sense I feel that, with the current knowledge on software "engineering", those who develop software are akin to artisans rather than engineers. Many people will disagree with my assertion, by mentioning a great variety of tools, languages, environments, etc. It is true that software development practices have achieved a lot of progress. However, as an engineering discipline and therefore from its scientific aspect, I think we are progressing very slowly. The reason is that there are few theories in software engineering that can really be qualified scientific and I will try to demonstrate it from epistemology viewpoint. Comments will be welcome.
10 citations
08 Jun 1998
TL;DR: A link from implementation properties to the requirement and design properties is given by interpreting a DC formula in a model of the executions of a TTS and then providing rules for lifting properties proved by structural induction for a T TS to DC formulas.
Abstract: This paper proposes a method for formal real-time systems development: Requirements and high level design decisions are time interval properties and are therefore specified in the Duration Calculus (DC), while implementations are described by timed transition systems (TTS). A link from implementation properties to the requirement and design properties is given by interpreting a DC formula in a model of the executions of a TTS and then providing rules for lifting properties proved by structural induction for a TTS to DC formulas. The method is illustrated by the Gas Burner case study.
8 citations
02 Dec 1998
TL;DR: A component model for software tools is presented in which tool components are characterized by the services they provide, require and optionally can use and the use of component-based systems to achieve a high degree of customizability is suggested.
Abstract: The recent interest in carrying out software engineering in a distributed manner could lead to a future increase in the contracting of software engineers, grouped into flexible, distributed software teams. One of the implications will be a requirement for more customizable software engineering environments to meet the diverse requirements of different projects. This paper examines customizability issues and suggests the use of component-based systems to achieve a high degree of customizability. A component model for software tools is presented in which tool components are characterized by the services they provide, require and optionally can use. Implementations of early prototypes, using JavaBeans components and employing the JavaBeans Activation Framework, are presented. The integration of legacy tools into the model is explored, and two mechanisms are presented: adapters encapsulate access to tools implemented in Java, and wrappers integrate other external tools.
07 Sep 1998
TL;DR: Novel Switched-Capacitor architectures for sampled-data analog half-band impulse sampled interpolations whose system responses are also immune to the input sample-and-hold filtering effect distortion are proposed.
Abstract: The half-band filtering technique is an efficient approach especially for 2-fold sampling rate alterations. This paper proposes novel Switched-Capacitor (SC) architectures for sampled-data analog half-band impulse sampled interpolations whose system responses are also immune to the input sample-and-hold filtering effect distortion. Three alternative architectures are investigated with their corresponding comparative superiority from the viewpoints of required number of amplifiers and passive SC branches as well as clock phases. An effective multistage implementation of SC interpolation based on the newly proposed half-band interpolators is also described with further comparison among traditional designs.
TL;DR: In this article, laser marking of stainless steel with a Q-switched Nd:YAG laser has been studied and the relationship between control factors and mark quality characteristics has been obtained.
Abstract: Laser marking of stainless steel with a Q-switched Nd:YAG laser has been studied in this paper. In experiments, three vital factors of a Q-switched Nd:YAG laser were chosen as control factors: electric current used for generating laser beam, pulse frequency and traverse speed of laser beam. Optical microscope and scanning electron microscope, surface profile instrument were used to measure effect of control factors on mark depth and width. An image-analysis system with a frame-grabber card and a charged-couple-device (CCD) was used to test mark contrast. The relationship between control factors and mark quality characteristics has been obtained.
TL;DR: In this article, the authors proposed new switched-capacitor (SC) active-delayed block (ADB) polyphase structures for analogue finite impulse response (FIR) interpolation.
Abstract: The authors propose new switched-capacitor (SC) active-delayed block (ADB) polyphase structures for analogue finite impulse response (FIR) interpolation. Their system functions are not distorted by the input sample-and-hold filtering effect at the lower input sampling rate. Both canonic and non-canonic ADB polyphase architectures which are superior in terms of a lower speed requirement for OAs, and fewer OAs, respectively, will be proposed for SC FIR interpolators.
02 Dec 1998
TL;DR: The differences between concept and measure are demonstrated, the risks to develop measures without clarifying concepts are shown, and the paramount importance of concept clarification and definition for the development of software measures are underlined.
Abstract: Defining concept before developing theory must be a fundamental requirement of any science. We show that this requirement, though seemingly trivial, is to a large extent not respected in software measurement research. Many basic software quality concepts are used ambiguously without a clear definition and consequently their measures, though growing in number, have no serious scientific foundation and risk being misleading in further research. We demonstrate the differences between concept and measure, show the risks to develop measures without clarifying concepts, and underline the paramount importance of concept clarification and definition for the development of software measures.
TL;DR: An experimental image-based VR system is introduced in which a set of panoramic images is used to compose the virtual environment and walking in the space is accomplished by “hopping” to differentPanoramic points.
Abstract: The most important goal of virtual reality is to create a virtual world by computers where users are allowed to view the environment and control the virtual objects interactively. Traditionally, virtual reality systems use 3D computer graphics to model and render a virtual environment in real time. However, this approach usually requires laborious modeling and expensive special-purpose rendering hardware. Image-based rendering is a new approach in composing a virtual environment in which a set of panoramic images is used to compose the virtual environment and walking in the space is accomplished by “hopping” to different panoramic points. This paper introduces an experimental image-based VR system. The techniques utilized in the system, in particular the authoring and interactive control tools of the system, are described in detail.
29 Oct 1998
TL;DR: In this paper, a few different methods, including low pass and Wiener adaptive beat sequenced filters, are applied and discussed to preserve beat to beat variance and late potentials as much as possible.
Abstract: Signal averaging is a general and effective method to reduce noise in ECG late potentials detection, but it may also extinguish the beat to beat variance. Other filters applied to the time sequence may destroy the late potentials when trying to filter out the noise. Filters, which are beat sequence originated, are proposed here to preserve beat to beat variance as well as late potentials as much as possible. A few different methods, including low pass and Wiener adaptive beat sequenced filters are applied and discussed.
18 May 1998
TL;DR: The integration of advanced telephone technologies, computer communication networks, data base technology, and electronically assisted detection of objects is studied and the developed solution offers several promising applications.
Abstract: The integration of advanced telephone technologies, computer communication networks, data base technology, and electronically assisted detection of objects is studied in the paper. The developed solution offers several promising applications. The system is in two parts: a detection module and an interactive voice response module.
Journal Article•
TL;DR: By using a given convergence result [Linear Algebra Appl. 232 (1996) 1], a superlinear convergence rate is obtained andumerical results are given to illustrate the rate of convergence.