Showing papers by "University of Macau published in 1996"
25 Aug 1996
TL;DR: Based on the types and abundances of biomarkers in the aliphatic and aromatic fractions of the extracts, as well as contaminant assemblages, a brief discussion has been made on the sources of organic compounds in air as discussed by the authors.
Abstract: Preliminary investigations were carried out on the extractable organic matter in aerosols and volatile organic compounds (VOCs) in ambient air of Guangzhou, Hongkong and Macao. Based on the types and abundances of biomarkers in the aliphatic and aromatic fractions of the extracts, as well as contaminant assemblages, a brief discussion has been made on the sources of organic compounds in air. Our studies reveal that organic compounds from incomplete combustion of fossil fuels, especially from vehicular exhaust, predominated both in aerosols and among VOCs in these samples. However, geological dust and modern living plants also contributed to the organics in ambient air.
30 citations
04 Dec 1996
TL;DR: The author demonstrates that the coupling model coincides with the empirical knowledge of software design and the metric developed can be used efficiently to guide software design.
Abstract: The author points out certain conceptual problems concerning module coupling and then presents a theoretical model of module coupling which offers a better understanding of the concept. The solution is based essentially on the evaluation of the complexity of each inter-module connection and for all connections the complexity of an inter-module connection is determined by the complexity of data relying on a recently developed data complexity method. Couplings for program logic control and assignment are compared and their ratio is determined. A formula to compute the coupling complexity of modules in a system is proposed. The author demonstrates that the coupling model coincides with the empirical knowledge of software design. Therefore, they believe that their coupling model has a clarified theoretical basis and the metric developed can be used efficiently to guide software design.
13 citations
TL;DR: It is shown that the spectrum of the preconditioned matrix is clustered around one and when the PCG method is applied to solve the system, the authors can expect a fast convergence rate.
Abstract: We study methods for solving the constrained and weighted least squares problem minx\(\min _x \tfrac{1}{2}\left( {b - Ax} \right)^T W\left( {b - Ax} \right)\) by the preconditioned conjugate gradient (PCG) method. HereW = diag (ω1, ⋯, ωm) with ω1 ≥ ⋯ ≥ ωm ≥ 0, andAT = [T1T, ⋯,TkT] with Toeplitz blocksTl eRn × n,l = 1, ⋯,k. It is well-known that this problem can be solved by solving anaugmented linear 2 × 2 block linear systemMλ +Ax =b, AT λ = 0, whereM =W−1. We will use the PCG method with circulant-like preconditioner for solving the system. We show that the spectrum of the preconditioned matrix is clustered around one. When the PCG method is applied to solve the system, we can expect a fast convergence rate.
11 citations
TL;DR: It is proved that the condition number of the preconditioned system is O(1), and an a priori bound on the number of iterations for convergence is obtained.
11 citations
TL;DR: A brief survey and unify the analysis of all these preconditioners for solving a large family of Toeplitz systems Tnx = b, which requires only O(n log n) operations by using these precONDitioners.
9 citations
TL;DR: In this paper, the authors proposed new switched-capacitor interpolators whose frequency responses are no longer affected by the input sample-and-hold filtering effect which occurred in previous circuits.
Abstract: The authors propose new switched-capacitor (SC) interpolators whose frequency responses are no longer affected by the input sample-and-hold filtering effect which occurred in previous circuits. Two different types of architectures are discussed, one for input sampled-and-held signals, and the other for arbitrary input signal formats. Examples are given to illustrate both types of SC interpolator circuits.
9 citations
13 Oct 1996
TL;DR: In this paper, Switched-Capacitor (SC) Infinite Impulse Response (IIR) Interpolators employing an efficient combination of active-delayed blocks (ADB) polyphase structures and recursive direct-form II structures with frequency responses no longer affected by the input sample-and-hold filtering effect are presented.
Abstract: This paper presents new Switched-Capacitor (SC) Infinite Impulse Response (IIR) Interpolators employing an efficient combination of Active-Delayed Blocks (ADB) polyphase structures and recursive direct-form II structures with frequency responses no longer affected by the input sample-and-hold filtering effect. Two different architectures are analysed: the first requires slower Operational Amplifiers (OAs) while the second allows the reduction of the number of clock phases and ADBs (1 OA per ADB). Examples are given to illustrate the behaviour of both types of SC interpolators with arbitrary input signal formats.
5 citations
01 Jan 1996
TL;DR: This paper applies Mean Value Calculus to specify and verify the steam-boiler control problem for Dagstuhl seminar and presents a fault-tolerant optimal design to make the system run as long as possible while the water sensor is broken down.
Abstract: Mean Value Calculus is a real-time interval logic which can be used to specify and reason about timing and logical constraints of real-time systems. In this paper, we apply it to specify and verify the steam-boiler control problem for Dagstuhl seminar. In addition to specifying safety requirement, emphasis is put on capturing non-functional requirements which reflect the qualities of designs, such as performance and optimization. Especially the fault-tolerant optimal design is presented to make the system run as long as possible while the water sensor is broken down.
5 citations
18 Aug 1996
TL;DR: In this article, two different types of polyphase architectures are discussed, one based on the Direct-Form (DF) and another employing Active-Delayed Blocks (ADB), with input sampled-and-held signals or with arbitrary input signal formats.
Abstract: This paper presents new Switched-Capacitor (SC) Finite Impulse Response (FIR) interpolators whose frequency responses are no longer affected by the input sample-and-hold filtering effect that occurred in previous circuits. Two different types of polyphase architectures are discussed, one based on the Direct-Form (DF) and another employing Active-Delayed Blocks (ADB). The DF polyphase structure is analysed either with input sampled-and-held signals or with arbitrary input signal formats, while the ADB structure is presented only with arbitrary input signal formats. Examples are given to illustrate both types of SC FIR interpolator circuits.
3 citations
Posted Content•
TL;DR: In this article, the authors proposed a contingency theory of organizations (CTO) framework to evaluate the impact of IT on financial information and corporate financial reporting (CFR) in a general, flexible and adaptive framework.
Abstract: Previous studies investigating IT impact on accounting suffer from a lack of theoretical guidance. An examination of the nature of information technology (IT), financial information and corporate financial reporting (CFR) indicates that the evaluation of IT impact on CFR requires a general, flexible and adaptive framework. Analogous to the contingency theory of organizations (CTO), this paper proposes such a framework. Its general assumptions are that the impact of IT on different aspects of CFR varies and the degree and pattern are contingent upon environmental, organizational, and managerial characteristics. Hypotheses have been developed to expand the framework. An evaluation of the framework against criticisms of CTO shows that it avoids several much criticized problems although care must be taken to ameliorate other pitfalls.
2 citations
25 Aug 1996
TL;DR: This work introduces topological invariants for distinguishing holes from external contours in digital images and demonstrates their relationship in Z/sup 2/ and indicates that the total curvature is an underlying concept for components.
Abstract: Recently, several topological invariants have been proposed for distinguishing holes from external contours in digital images. We first introduce these invariants and then demonstrate their relationship in Z/sup 2/. From the total curvature, all the other invariants can be deduced. It indicates that the total curvature is an underlying concept for components. As an application, an algorithm for labelling connected components based on these invariants is proposed. Comparing to existing methods, the approach using the contour invariants is simpler and more efficient.
14 Oct 1996
TL;DR: The presented hybrid environment represents a knowledge-based support of engineering computation that facilitates autonomous control of the computational process, providing not only a user-friendly environment, but also an active and predictive support of the user.
Abstract: The presented hybrid environment represents a knowledge-based support of engineering computation. The knowledge-based subsystem is partially realized in PROLOG, supporting an engineering software system written in a conventional programming language (typically in C). In an effort (i) to bring the latter component together with the PROLOG-oriented subsystem, and (ii) to increase the intelligence of the environment, selected PROLOG features are modelled in the environment of the chosen conventional programming language. The intrinsic intelligence of the environment can be increased particularly by registering whether or not variables are installed. This facilitates autonomous control of the computational process, providing not only a user-friendly environment, but also an active and predictive support of the user. Several practical applications were developed based on this concept.
TL;DR: In this article, it is proved mathematically that the strain-stress function F(ξ, φ) on the cylindrical shell theory suggested by Vlasov[5] will give out the general solution of the simultaneous partial differential equations of the CWS problem.
Abstract: It is proved mathematically in this paper that the strain-stress function F(ξ, φ) on the cylindrical shell theory suggested by Vlasov[5] will give out the general solution of the simultaneous partial differential equations of cylindrical shell problem. That is to say, there is no any solution of the simultaneous partial differential equations can be omitted due to Vllsov's suggestion. The conclusion suggested in this paper is helpful to the well-known Vlasov's method.
TL;DR: Les auteurs signalent pour la premiere fois la presence des phlebotomes a Macao, Territoire du Sud de the Chine sous administration portugaise.
Abstract: Les auteurs signalent pour la premiere fois la presence des phlebotomes a Macao, Territoire du Sud de la Chine sous administration portugaise Dix-neuf adultes (14 mâles et 5 femelles) ont ete captures dans une grotte artificielle en septembre 1994. Les caracteres observes sont conformes a la description de l'espece Sergentomyia barraudi (Sinton, 1929).