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Research Collection School Of Computing and Information Systems

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Full-Text Articles in Computer Sciences

A Survey Of Expert Systems In Singapore And The Integration Of Multimedia Technology And Expert Systems, Arcot Desai Narasimhalu Aug 1993

A Survey Of Expert Systems In Singapore And The Integration Of Multimedia Technology And Expert Systems, Arcot Desai Narasimhalu

Research Collection School Of Computing and Information Systems

Expert systems technologies have been widely adopted by different industries form the early 1980s. There have been examples of expert systems embedded in applications developed for the financial and banking sector, manufacturing, services and government. In section 2 of this paper, we present a scan of expert systems used in different sectors. Section 3 will cover the expert system tools and applications developed in the decade of the 1980s. Section 4 will present some of the ongoing expert systems related activities. Section 5 will extrapolate the present work to forecast the future types of expert systems that might be developed …


Memory-Adaptive External Sorting, Hwee Hwa Pang, Michael J. Carey, Miron Livny Aug 1993

Memory-Adaptive External Sorting, Hwee Hwa Pang, Michael J. Carey, Miron Livny

Research Collection School Of Computing and Information Systems

In real-time and goal-oriented database systems, the amount of memory assigned to queries that sort or join large relations may fluctuate due to contention from other higher priority transactions. This study focuses on techniques that enable external sorts both to reduce their buffer usage when they lose memory, and to effectively utilize any additional buffers that are given to them. We also show how these techniques can be extended to work with sort-merge joins. A series of experiments confirms that our proposed techniques are useful for sorting and joining large relations in the face of memory fluctuations.


Performance Analysis Of Interconnected Lans With Server/Client Configuration, Jiangling Du, Robert H. Deng, Chi Chung Ko Jul 1993

Performance Analysis Of Interconnected Lans With Server/Client Configuration, Jiangling Du, Robert H. Deng, Chi Chung Ko

Research Collection School Of Computing and Information Systems

In this paper, we study the end-to-end performance of interconnected local area networks (LAN) with server/client configuration. The system uses bridges to connect two token-ring LANs through a high-speed communication link. A server station located on one LAN receives requests from client-stations on the same LAN as well as on the remote LAN, processes the requests, and returns responses to the client-stations. The end-to-end connections of the interconnected network are modelled as single-chain and multiple-chain closed queueing systems, which are solved by an iterative algorithm based on the MVA (mean value analysis) method. The performance examples are shown in terms …


Performance Of A Token-Passing System With Batch Arrivals And Its Application To File Transfers, Robert H. Deng, Xuanyu Zhang, Kuan Tase Huang Jul 1993

Performance Of A Token-Passing System With Batch Arrivals And Its Application To File Transfers, Robert H. Deng, Xuanyu Zhang, Kuan Tase Huang

Research Collection School Of Computing and Information Systems

This paper investigates the performance of token-passing systems with limited service and Poisson arrivals. For pure Poisson arrivals, the Laplace-Stieltjes Transform (LST) of an approximate customer/packet waiting time distribution is derived and expressed as a functional equation, from which the approximate mean and variance of waiting time are obtained; for batch Poisson arrivals, an approximate mean of waiting time is derived. Mean waiting time approximations are compared against both simulation results and other results presented in the literature; the variance approximation is evaluated by comparing it to simulation results only, since no other results on variance have been reported so …


Partially Preemptible Hash Joins, Hwee Hwa Pang, Michael J. Carey, Miron Livny May 1993

Partially Preemptible Hash Joins, Hwee Hwa Pang, Michael J. Carey, Miron Livny

Research Collection School Of Computing and Information Systems

With the advent of real-time and goal-oriented database systems, priority scheduling is likely to be an important feature in future database management systems. A consequence of priority scheduling is that a transaction may lose its buffers to higher-priority transactions, and may be given additional memory when transactions leave the system. Due to their heavy reliance on main memory, hash joins are especially vulnerable to fluctuations in memory availability. Previous studies have proposed modifications to the hash join algorithm to cope with these fluctuations, but the proposed algorithms have not been extensively evaluated or compared with each other. This paper contains …


Entity Identification In Database Integration, Ee Peng Lim, Jaideep Srivastava, Satya Prabhakar, James Richardson Apr 1993

Entity Identification In Database Integration, Ee Peng Lim, Jaideep Srivastava, Satya Prabhakar, James Richardson

Research Collection School Of Computing and Information Systems

The objective of entity identification is to determine the correspondence between object instances from more than one database. Entity identification at the instance level, assuming that schema level heterogeneity has been resolved a priori, is examined. Soundness and completeness are defined as the desired properties of any entity identification technique. To achieve soundness, a set of identity and distinctness rules are established for entities in the integrated world. The use of extended key, which is the union of keys, and possibly other attributes, from the relations to be matched, and its corresponding identify rule are proposed to determine the equivalence …


Federated Autonomous Databases: Project Overview, Satya Prabhakar, Jiandong Huang, James Richardson, Jaideep Srivastava, Ee Peng Lim, Sham Navathe, Ashok Savarase, Mark Foresti Apr 1993

Federated Autonomous Databases: Project Overview, Satya Prabhakar, Jiandong Huang, James Richardson, Jaideep Srivastava, Ee Peng Lim, Sham Navathe, Ashok Savarase, Mark Foresti

Research Collection School Of Computing and Information Systems

The paper presents an overview of an ongoing research program, Federated Autonomous Databases, sponsored by Rome Laboratory (US Air Force) and conducted by Honeywell in collaboration with the University of Minnesota and Georgia Institute of Technology. This program is exploratory in nature and is aimed at understanding and solving, within the scope of the program definition, the problem of providing integrated access to distributed, heterogeneous and autonomous databases.


Observation Of B0 Decay To Two Charmless Mesons, M. Battle, Manoj Thulasidas Jan 1993

Observation Of B0 Decay To Two Charmless Mesons, M. Battle, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

We report results from a search for the decays B0→π+π-, B0→K+π-, and B0→K+K-. We find 90% confidence level upper limits on the branching fractions, Bππ


Repository Evaluation Of Software Reuse: An Empirical Study, R. D. Banker, Robert J. Kauffman, D. Zweig Jan 1993

Repository Evaluation Of Software Reuse: An Empirical Study, R. D. Banker, Robert J. Kauffman, D. Zweig

Research Collection School Of Computing and Information Systems

The use and benefits of repository evaluation of software reuse are illustrated through an analysis of the evolving repositories of two large firms that recently implemented integrated CASE development tools. The analysis shows that these tools have supported high levels of software reuse, but it also suggests that there remains considerable unexploited reuse potential. The findings indicate that organizational changes will be required before the full potential of the new technology can be realized.


Measurement Of Charmless Semileptonic Decays Of B Mesons, Bartelt; J.; Et Al., M. Thulasidas Jan 1993

Measurement Of Charmless Semileptonic Decays Of B Mesons, Bartelt; J.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.


Evidence For Penguin-Diagram Decays: First Observation Of B→K*(892)Γ, R. Ammar, M. Thulasidas Jan 1993

Evidence For Penguin-Diagram Decays: First Observation Of B→K*(892)Γ, R. Ammar, M. Thulasidas

Research Collection School Of Computing and Information Systems

We have observed the decays B0→K*(892)0γ and B−→K*(892)−γ, which are evidence for the quark-level process b→sγ. The average branching fraction is (4.5±1.5±0.9)×10−5. This value is consistent with standard model predictions from electromagnetic penguin diagrams.


Search For Τ-→Γμ-: A Test Of Lepton Number Conservation, A. Bean, M. Thulasidas Jan 1993

Search For Τ-→Γμ-: A Test Of Lepton Number Conservation, A. Bean, M. Thulasidas

Research Collection School Of Computing and Information Systems

A search for the lepton mumber violating decay of the τ lepton to the γμ final state has been performed with the CLEO II detector at the Cornell e+e− storage ring CESR. In a data sample that corresponds to an integrated luminosity of 1.55 fb−1, we observe no candidates in the signal region. We thus determine an upper limit of B(τ−→γμ−)


Study Of D0 Decays Into K̄0 And K̄*0, M. Procario, M. Thulasidas Jan 1993

Study Of D0 Decays Into K̄0 And K̄*0, M. Procario, M. Thulasidas

Research Collection School Of Computing and Information Systems

Using the CLEO II detector at CESR we have studied D0 decays into final states with a ¯K0 or ¯K*0, and have measured branching ratios for the decay modes D0→(¯K0¯K*0)π0, η, η′. These results are compared with predictions of various charm decay models, and contributions of final-state interactions are discussed.


A Rule-Based System For Query Feedback, Hock C. Chan, Kwok-Kee Wei, Keng Siau Jan 1993

A Rule-Based System For Query Feedback, Hock C. Chan, Kwok-Kee Wei, Keng Siau

Research Collection School Of Computing and Information Systems

The authors propose a rule-based system which provides feedback in order to give the user a better understanding of the user's queries. This technique improves query accuracy and confidence. A rule-based expert system that pinpoints syntax errors is described. It suggests possible semantics errors and provides possible solutions, as well as the English translation for the queries. The system can be used for computer-aided training and in actual operations. The system was experimentally tested with a group of students.


Tau Decays With One Charged Particle Plus Multiple Π0'S, M. Procario, Manoj Thulasidas Jan 1993

Tau Decays With One Charged Particle Plus Multiple Π0'S, M. Procario, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

With the CLEO-II detector at the Cornell Electron Storage Ring, we have measured branching fractions for tau lepton decay into one-prong final states with multiple π0’s B0hnπ, normalized to the branching fraction for tau decay into one charged particle and a single π0. We find B0h2π/B0hπ=0.345±0.006±0.016, B0h3π/B0hπ=0.041 ±0.003±0.005, and B0h4π/B0hπ=0.006±0.002±0.002.


Observation Of The Charmed Baryon C+ And Measurement Of The Isospin Mass Splittings Of The C, Crawford, G.; Et Al., M. Thulasidas Jan 1993

Observation Of The Charmed Baryon C+ And Measurement Of The Isospin Mass Splittings Of The C, Crawford, G.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.


A Case Tool For Conceptual Database Design, Keng Siau, Kok Phuang Tan, Hock Chuan Chan Dec 1992

A Case Tool For Conceptual Database Design, Keng Siau, Kok Phuang Tan, Hock Chuan Chan

Research Collection School Of Computing and Information Systems

The paper describes a Computer Aided Software Engineering (CASE) tool to support conceptual database modelling. One popular approach for conceptual database modelling is use of the Entity-Relationship (ER) model. The paper proposes the use of an Enhanced Entity-Relationship (EER) model for conceptual database modelling. This Enhanced Entity-Relationship model extends the Entity-Relationship model by incorporating the generalization/specialization, aggregation and categorization abstractions. The CASE tool, which is based on the Enhanced Entity-Relationship model, is known as the Enhanced Entity-Relationship Diagrammer (EERD). In addition, the CASE tool supports direct visual query and update based on the EERM.


A Participants' Dss For A Management Game With A Dss Generator, G. K. Yeo, Fiona Fui-Hoon Nah Sep 1992

A Participants' Dss For A Management Game With A Dss Generator, G. K. Yeo, Fiona Fui-Hoon Nah

Research Collection School Of Computing and Information Systems

A decision support system for a management game has been built with emphasis on total model integration, easy database access, and efficient model building by participants themselves. A decision-support-system generator has been used to provide a wide range of modeling capabilities. This article describes its design principles and major features.


Deterministic Approximations To Co-Production Problems With Service Constraints And Random Yields, Gabriel R. Bitran, Thin Yin Leong May 1992

Deterministic Approximations To Co-Production Problems With Service Constraints And Random Yields, Gabriel R. Bitran, Thin Yin Leong

Research Collection School Of Computing and Information Systems

Production planning problems where multiple item categories are produced simultaneously are examined. The items have random yields and are used to satisfy the demands of many products. These products have specification requirements that overlap. An item originally targeted to satisfy the demand of one product may be used to satisfy the demand of other products when it conforms to their specifications. Customers' demand must be satisfied from inventory. The problem is formulated with service constraints and a near-optimal solution is provided to the problem with a fixed planning horizon. Simple heuristics are proposed for the problem solved with a rolling …


Measurement Of The Tau Lepton Electronic Branching Fraction, D. Akerib, M. Thulasidas Jan 1992

Measurement Of The Tau Lepton Electronic Branching Fraction, D. Akerib, M. Thulasidas

Research Collection School Of Computing and Information Systems

The tau lepton electron branching fraction has been measured with the CLEO II detector at the Cornell Electron Storage Ring as Be=0.1749±0.0014±0.0022, with the first error statistical and the second systematic. The measurement involves counting electron-positron annihilation events in which both taus decay to electrons, and normalizing to the number of tau-pair decays expected from the measured luminosity. Detected photons in these events constitute a definitive observation of tau decay radiation.


Isospin Mass Splittings From Precision Measurements Of D*-D Mass Differences, D. Bortoletto, Manoj Thulasidas Jan 1992

Isospin Mass Splittings From Precision Measurements Of D*-D Mass Differences, D. Bortoletto, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

Using the decay modes, D*+→D+π0 and D*0→D0π0, we have measured the D*+−D+ and D*0−D0 mass differences to be 140±0.08±0.06 and 142.12±0.05±0.05 MeV, respectively. Combining these measurements with the Particle Data Group average for the D*+−D0 mass difference, we obtain isospin mass splittings for D*+−Dusp*0 and D+−D0 of 3.32±0.08±0.05 and 4.80±0.10 ±0.06 MeV. We discuss the implications of these measurements for models of isospin mass differences and model-dependent estimates of fD.


Measurement Of Τ Decays Involving Η Mesons, M. Artuso, M. Thulasidas Jan 1992

Measurement Of Τ Decays Involving Η Mesons, M. Artuso, M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.


Electronic Branching Ratio Of The Lepton, R. Ammar, Manoj Thulasidas Jan 1992

Electronic Branching Ratio Of The Lepton, R. Ammar, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

Using data accumulated by the CLEO I detector operating at the Cornell Electron Storage Ring, we have measured the ratio R=Γ(τ→eν¯eντ)Γ1 where Γ1 is the τ decay rate to final states with one charged particle. We find R=0.2231±0.0044±0.0073 where the first error is statistical and the second is systematic. Together with the measured topological one-charged-particle branching fraction, this yields the branching fraction of the τ lepton to electrons, Be=0.192±0.004±0.006.


Query Optimization In Oodb, Hwee Hwa Pang, Hongjun Lu, Beng Chin Ooi Jan 1992

Query Optimization In Oodb, Hwee Hwa Pang, Hongjun Lu, Beng Chin Ooi

Research Collection School Of Computing and Information Systems

In object-oriented databases, relationships are generally maintained explicitly. The partial result of a retrieved object can be used to efficiently retrieve related objects. Instead of optimizing joins as in relational database systems, pointer chasing is optimized in object-oriented database systems. Further, semantics inherent in the object-oriented database, like superclass-subclass relationships and composite-component relationships between object classes, must be realised. In this paper, we describe our initial result in query optimization in an object-oriented database system. Semantic query transformation is used to preprocess the query. semantically optimized query is then translated into a query evaluation plan which comprises method invocations that …


Knowledge-Based Systems Approach For Offshore Safety Training, B. S. Lee, Venky Shankararaman Dec 1991

Knowledge-Based Systems Approach For Offshore Safety Training, B. S. Lee, Venky Shankararaman

Research Collection School Of Computing and Information Systems

A number of training methods has been used within the offshore industry to impart safety knowledge and safe operating skills. In this paper a Knowledge-Based Safety Training architecture is proposed. The architecture uses both expert system and hypertext methods and is also applicable to plants other than offshore platforms. Special attention is given to the types of knowledge dealt with in safety training and how to represent this knowledge and teach it using various teaching strategies.


Representation Requirements For Supporting Knowledge-Based Construction Of Decision-Models In Medicine, Tze-Yun Leong Nov 1991

Representation Requirements For Supporting Knowledge-Based Construction Of Decision-Models In Medicine, Tze-Yun Leong

Research Collection School Of Computing and Information Systems

This paper analyzes the medical knowledge required for formulating decision models in the domain of pulmonary infectious diseases (PIDs) with acquired immunodeficiency syndrome (AIDS). Aiming to support dynamic decision-modeling, the knowledge characterization focuses on the ontology of the clinical decision problem. Relevant inference patterns and knowledge types are identified.


Reuse And Productivity In Integrated Computer-Aided Software Engineering: An Empirical Study, Rajiv D. Banker, Robert J. Kauffman Sep 1991

Reuse And Productivity In Integrated Computer-Aided Software Engineering: An Empirical Study, Rajiv D. Banker, Robert J. Kauffman

Research Collection School Of Computing and Information Systems

Growing competition in the investment banking industry has given rise to increasing demand for high functionality software applications that can be developed in a short period of time. Yet delivering such applications creates a bottleneck in software development activities. This dilemma can be addressed when firms shift to development methods that emphasize software reusability. This article examines the productivity implications of object and repository-based integrated computer-aided software engineering (ICASE) software development in the context of a major investment bank's information systems strategy. The strategy emphasizes software reusability. Our empirical results, based on data from 20 projects that delivered software for …


Visual Knowledge Query Language As A Front-End To Relational Systems, Keng Siau, Kok Phuang Tan, Hock Chuan Chan Sep 1991

Visual Knowledge Query Language As A Front-End To Relational Systems, Keng Siau, Kok Phuang Tan, Hock Chuan Chan

Research Collection School Of Computing and Information Systems

Relational query languages like SQL and QUEL require the users to understand the complex database structure. This is a burden on end users, especially novice end users who access the database on a casual and infrequent basis. To alleviate the need to know the logical database organization, this paper proposes the use of a semantic data model, known as the Enhanced Entity-Relationship (EER) model, as a front-end to the relational systems. A formal, high-level Visual Knowledge Query Language (VKQL) has also been designed for this interface. This language provides for knowledge abstraction as the user communicates only domain knowledge with …


Visual Knowledge Query Language As A Front-End To Relational Systems, Keng Siau, Kok Phuang Tan, Hock Chuan Chan Sep 1991

Visual Knowledge Query Language As A Front-End To Relational Systems, Keng Siau, Kok Phuang Tan, Hock Chuan Chan

Research Collection School Of Computing and Information Systems

Relational query languages like SQL and QUEL require the users to understand the complex database structure. This is a burden on end users, especially novice end users who access the database on a casual and infrequent basis. To alleviate the need to know the logical database organization, this paper proposes the use of a semantic data model, known as the Enhanced Entity-Relationship (EER) model, as a front-end to the relational systems. A formal, high-level Visual Knowledge Query Language (VKQL) has also been designed for this interface. This language provides for knowledge abstraction as the user communicates only domain knowledge with …


Representation Requirements For Supporting Decision-Model Formulation, Tze-Yun Leong Jul 1991

Representation Requirements For Supporting Decision-Model Formulation, Tze-Yun Leong

Research Collection School Of Computing and Information Systems

This paper outlines a methodology for analyzing the representational support for knowledge-based decision-modeling in a broad domain. A relevant set of inference patterns and knowledge types are identified. By comparing the analysis results to existing representations, some insights are gained into a design approach for integrating categorical and uncertain knowledge in a context sensitive manner.