Showing papers by "Hong Kong University of Science and Technology published in 1993"

A New Approach to Country Segmentation Utilizing Multinational Diffusion Patterns

Abstract: Country segmentation has been proposed to assist in marketing strategy decisions for international marketing managers. Such schemes typically consist of grouping or clustering a set of specified countries on the basis of a wide array of macroeconomic variables. The authors focus on the merits of such country classification schemes in gaining an understanding about multinational diffusion patterns. More specifically, they analyze the extent to which countries belonging to the same (different) grouping reveal similar (dissimilar) diffusion patterns. To that end, they compare the results of traditional segmentation approaches with diffusion-based country segments derived for three different consumer durable goods. For the latter, they rely on a recently developed latent-structure methodology, here modified to accommodate the Bass diffusion model, which simultaneously determines the segments and segment-level estimates of the diffusion parameters. They find that the market segments derived from these two approaches differ dramatically and that macro-level variables do not fully explain differences in diffusion patterns across countries. In addition, country segments formed on the basis of diffusion patterns often differ by product. Finally, they discuss some managerial implications and directions for future research.

Genetic motion search algorithm for video compression

Abstract: A new approach to block-based motion estimation for video compression, called the genetic motion search (GMS) algorithm, is introduced. It makes use of a natural processing concept called genetic algorithm (GA). In contrast to existing fast algorithms, which rely on the assumption that the matching error decreases monotonically as the search point moves closer to the global optimum, the GMS algorithm is not fundamentally limited by this restriction. Experimental results demonstrate that GMS is more robust than other algorithms in locating the global optimum and is computationally simpler than the full search algorithm. GMS is also suitable for VLSI implementation because of its regularity and high architectural parallelism. >

The World Price of Foreign Exchange Risk

Abstract: We consider a world capital market in which the investor population is heterogenous. Investors of different countries differ in the prices of goods at which they consume the income from their investments. In such a setting, the international CAPM incorporates rewards for exchange rate risk, in addition to the traditional reward for market-covariance risk. The aim of the paper is to determine whether these additional risk premia empirically playa significant role in the pricing of securities. The test being conducted is a test of a conditional version of the CAPM. It builds on the recent empirical literature which points out that stock market returns may, to some extent, be predicted on the basis of a number of instrumental variables, such as interest rates and dividend yields. All previous tests of the international CAPM with exchange risk premia have been tests of the unconditional version and have been inconclusive.

An Exploration of the Expertness of Outside Informants

Abstract: This study reviews the use of outside informants—individuals not employed in the firm being studied—in strategy research reported in major journals. We empirically explored the expertness of these ...

Numerical studies of a 36-site kagomé antiferromagnet

Abstract: The ground-state wave function for the spin-1/2 quantum antiferromagnet on a 36-site kagome$iaa--- structure is found by numerical diagonalization. Spin-spin correlations and spin gaps indicate that the ground state of this system does not possess magnetic order. The spin-Peierls order is studied using a four-spin correlation function. The short-range structure in this correlation function is found to be consistent with a simple dimer-liquid model. The spin-Peierls order, if it exists, must be quite small.

Time-resolved optical tomography

Abstract: We have obtained transaxial slice images of a cylindrical object containing a highly scattering, low-absorbing solution by using picosecond pulses of visible light. Embedded in the solution was an assortment of six glass tubes containing different concentrations of absorbing dye. We reconstructed images tomographically from projections generated by using light transmitted through the object with the shortest flight times.

From Postmodern Anthropology to Deconstructive Ethnography

Abstract: The social sciences have recently exhibited renewed interest in ethnography while traditional anthropology has been struggling with the challenges of postmodernism. This paper considers the theoretical implications of the potential convergence of these strands, with particular reference to the ethnography of organizations. Postmodernism is seen to affect ethnography by problematizing the processes of description, reference, and the establishment of authority in ethnographic texts. It offers, rather than a "scientific" model, a "literary" model of such texts in which description is an active construction rather than a neutral recording of the other's world. Ostensive reference becomes displaced by evocation, the single authorial voice by the "heteroglossia" of many contributing voices. Unfortunately, there is a tendency for the processes of interpretation to be abandoned to a free play of unlimited signification in which any and all meanings are possible, which jettisons rigor and with it critical acerbity...

Financial Ratios and Corporate Endurance: A Case of the Oil and Gas Industry*

Abstract: . A major function of financial statement analysis is to assess the risk of financial distress. Since Beaver's (1966) and Altaian's (1968) pioneering works, voluminous studies have been devoted to exploring the use of accounting information in predicting business failure. We apply survival analysis to study a class of financial distress when a financial analyst can identify an event that sets off the dynamic process of business adversity and would like to find out how long a firm can endure the adversity. We use the case of the oil and gas industry during the turmoil of the early 1980s and apply survival analysis to study how long a firm can endure this drastic oil price decline before facing financial distress. Our results indicate that the liquidity ratio, leverage ratio, operating cash flows, success in exploration, age, and size are significant factors affecting corporate endurance. Resume. Une fonction majeure de l'analyse des etats financiers consiste a evaluer le risque de difficultes financieres. Depuis les travaux d'amorce de Beaver et Altman, de volumineuses etudes ont ete consacrees a l'analyse approfondie de l'utilisation de l'information comptable dans la prediction des faillites d'entreprises. Les auteurs appliquent l'analyse de survie a l'etude d'une categorie de difficultes financieres pour laquelle l'analyste financier parvient a determiner un evenement qui declenche le processus dynamique des difficultes de l'entreprise et aimerait determiner pendant combien de temps cette derniere pourra resister a ces difficultes. Les auteurs evoquent le cas du secteur petrolier et gazier au cours de la periode tumultueuse du debut des annees 80 et appliquent l'analyse de survie a l'etude du temps pendant lequel une entreprise pouvait resister a un declin radical du prix du petrole avant d'eprouver des difficultes financieres. Les resultats de l'etude demontrent que le ratio de liquidite, le ratio de levier, les flux monetaires provenant de l'exploitation, le succes des activites d'exploration, l'âge et la taille de l'entreprise sont des facteurs importants qui influent sur sa resistance.

Learning transformation rules for semantic query optimization: a data-driven approach

Abstract: An approach to learning query-transformation rules based on analyzing the existing data in the database is proposed. A framework and a closure algorithm for learning rules from a given data distribution are described. The correctness, completeness, and complexity of the proposed algorithm are characterized and a detailed example is provided to illustrate the framework. >

Modeling correlation in software recovery blocks

Abstract: The authors examine the problem of accurately modeling the software fault-tolerance technique based on recovery blocks. Analysis of some systems have investigated the correlation between software modules, which may be due to a portion of the functional specification that is common to all software modules, or to the inherent hardness of some problems. Three types of dependence which can be captured using measurements are considered. These are correlation between software modules for a single input, correlation between successive acceptance tests on correct module outputs and incorrect module outputs, and correlation between subsequent inputs. The authors' technique is quite general and can be applied to other types of correlation. In accounting for dependence, they use the intensity distribution introduced by D.E. Eckhardt and L.D. Lee (1985). A method of generating the intensity distribution that is based on the pairwise correlation between modules is discussed. This method is contrasted with the assumption of independent modules as well as the use of the beta-binomial density introduced by V.F. Nicola and A. Goyai (1990). The effects of dependencies were studied using a Stochastic Reward Network (SRN) that incorporates all of the above dependencies and a modeling tool called Stochastic Petri Net Package (SPNP). >

Enhancement of the third-order nonlinear optical susceptibility in Si quantum wires.

Abstract: Recent observation of efficient light emission from porous silicon has attracted much attention and renewed interests in the study of nonlinear optical properties of nanometer-sized quantum systems. In this paper, we study the third-order nonlinear optical susceptibility of semiconductor quantum wires. The quantum wires are taken to be circular columns with a cross section size of \ensuremath{\sim}1 nm. The excitonic effects are taken to be the major electronic excitations. We find that the quantum confinement of the excitons greatly enhances the third-order optical nonlinear susceptibility in a quantum wire. The source of the enhancement is primarily the confinement-induced localization of excitons. The large enhancement of the third-order optical nonlinearity estimated here is consistent with the recent observation of the efficient infrared-up-conversion luminescence in porous silicon.

From Production Systems to Learning Systems: Lessons from Japan:

Abstract: The need to advance the conventional understanding of production systems as fixed flows of goods and services to dynamic systems based on learning is discussed. The theory advanced is based on research on the Japanese robot industry. The paper opens with a discussion of the meaning of flexibility in a dynamic economy to expose the social division of labour as the foundation of the creation and evolution of production systems. Production systems are established to obtain the scale and scope economies offered by the independent firms of the social division of labour. The necessity to organize production requires the creation of some type of an internal or external governance structure. The Japanese have developed a social technology that resolves the transaction cost trade-offs confronting North American industry between internal and external governance structures. Asanuma's relation-specific skill is discussed as the crux for comprehending the shift from production systems to learning systems.

Spin-1/2 quantum antiferromagnets on the triangular lattice.

Abstract: The spin-1/2 anisotropic Heisenberg antiferromagnet is studied at T=0 on the triangle lattice via numerical diagonalization for system sizes up to N=36 sites. Extrapolation to the thermodynamic limit suggests that the isotropic system possesses no, or very small, \ensuremath{\surd}3 \ifmmode\times\else\texttimes\fi{} \ensuremath{\surd}3 magnetic order; no helical or chiral order; and spin-spin correlations consistent with that of a critical phase. For XY-like anisotropy there is long-ranged \ensuremath{\surd}3 \ifmmode\times\else\texttimes\fi{} \ensuremath{\surd}3 magnetic order. In contrast to bipartite lattices, the standard first- and second-order spin-wave theories are not quantitatively accurate. Excitation energy gaps suggest that the lowest lying excitations for the isotropic point are not spin-flip excitations in the thermodynamic limit. The results for the isotropic point appear to agree with recent series expansion, large-N expansion, and the original resonating valence bond picture of Anderson, although they cannot be considered as conclusive evidence supporting any of these theories.

A JPEG-based interpolative image coding scheme

Abstract: The primary goal was to reduce the blocking artifacts that would be produced by using the standard JPEG when the bit rate is very low. In order to test the proposed scheme and compare it with the standard JPEG, extensive computer simulations have been performed. As compared with the standard JPEG, the efficiency of the proposed interpolative scheme has been enhanced and the blocking artifacts have been reduced significantly, thus yielding a much more pleasant visual result. >

A Comparative Analysis of Inductive-Learning Algorithms

Abstract: Recently there has been an increasing interest in applying inductive learning algorithms to generate rules/patterns from a given example set. While such approaches serve as an efficient way of resolving the knowledge-acquisition bottleneck, their predictive accuracy, which is the popular measure of performance, varies widely. This paper contrasts major inductive-learning algorithms and examines their performance with two performance measures: the predictive accuracy and the representation language. Experiments involved three inductive-learning algorithms and five different managerial tasks in construction project assessment and bankruptcy-prediction domains. The test results indicate that the model performance is dependent on tasks with an exception of the neural network model and that there is a an effect of group proportion in the example set used to construct the model. The neural network approach presents relatively stable predictive power across different task domains, although it is difficult to interpret its representation.

Using statecharts to model hypertext

Abstract: This paper describes how to use statecharts to model hypertext. Statechart is a formal graphical model based on state transition diagram and hypergraph. The statechart model is compared with other models for hypertext based on simple node-and-link graph, first-order logic formulae, hypergraph, and petri net. The features of statecharts relevant to the modeling of hypertext are described. Statecharts for the common features in frame-based and scrolling-based hypertext are given. Then statecharts are used to model the various buttons supported in a real-life production hypertext system, Guide (both the Unix version and the version marketed by Owl International Inc.). These examples illustrate that statecharts can be used to abstract the structure from the content of hypertext, and to model the structure and the browsing semantics of hypertext clearly and vividly.

Interpolative BTC image coding with vector quantization

Abstract: The authors suggest two interpolative block truncation coding (BTC) image coding schemes with vector quantization and median filters as the interpolator. The first scheme is based on quincunx subsampling and the second one on every-other-row-and-every-other-column subsampling. It is shown that the schemes yield a significant reduction in bit rate at only a small performance degradation and, in general, better channel error resisting capabilities, as compared to the absolute moment BTC. The methods are further demonstrated to outperform the corresponding BTC schemes with pure vector quantization at the same bit rate and require minimal computations for the interpolation. >

Community Structure and Standing Crop Biomass of a Mangrove Forest in Futian Nature Reserve, Shenzhen, China

Abstract: The community structure and standing crop biomass of a mangrove forest in Futian Nature Reserve, Shenzhen, the People’s Republic of China was studied. This mangrove, located towards the northern latitudinal limit of the mangrove development (22°N), had relatively simple structure and low diversity (the Shannon-Wiener index was 0.78). The three dominant species, namely Aegiceras corniculatum, Kandelia candel and Avicennia marina, possess importance values of 72, 19 and 9%, respectively. The average height of the mangrove community was 4.5 m with no vertical stratification. The values of tree density of A. corniculatum and A. marina were found to be 5290 and 260 ha−1, respectively. The biomass of both A. corniculatum and K. candel was best estimated from regression equations using a combination of height and diameter at breast height as the independent variables. For Avicennia marina, there was no simple correlation between biomass and height or diameter. The regression models suggested by previous workers did not give satisfactory estimation of biomass of A. marina in this mangrove forest. The total biomass of this mangrove forest was 12.1 kg m−2, with 73% of such production contributed by A. corniculatum and 8% by A. marina. Because of its small percentage, the inaccuracy in estimating biomass of A. marina did not affect the overall determination of biomass of the whole community. Average above-ground biomass was 8.7 kg m−2 (72% of the total biomass) and the major components were aerial woody tissues, stems and branches. The rootshoot ratio of this plant community was 0.4:1.

A Bonhoeffer-van der Pol oscillator model of locked and non-locked behaviors of living pacemaker neurons

Abstract: A recent investigation of the influence of periodic inhibitory trains on a crayfish pacemaker neuron showed not only well-known locked periodic responses but also intermittent, messy, and hopping responses. This communication studies the responses of the Bonhoeffer-van der Pol (BVP) model with self-sustained oscillation when exposed to periodic pulse trains inputs. The analysis is similar to that used in crayfish and reveals interesting features, both comparable and complementary to those seen in the living preparation.

Database supported cooperative problem solving

Abstract: Cooperative problem solving can be viewed as a complex activity requiring harmonious and dynamic interaction between active agents and passive agents. This problem is currently being addressed by the research community at various levels of abstraction. Broadly, this paper analyzes the problem of cooperative problem solving from a database perspective and argues that recent advances in database technology facilitate development of a viable solution to the above problem. Specifically, in this paper, we first analyze the problem of cooperative problem solving to identify its underlying key characteristics. Based upon our analysis, we partition the problem space into classes along a spectrum and indicate the level of cooperation required. We propose near-term as well as long-term solutions for cooperative problem solving that progressively enhances the functionality of database systems by synthesizing appropriate abstractions and techniques. Furthermore, we identify problems, such as agent capability modeling that require further research to address the most general form of cooperative problem solving.