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Research Collection School Of Computing and Information Systems

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Articles 6811 - 6840 of 6884

Full-Text Articles in Physical Sciences and Mathematics

A Measurement Of B(D+S → Φl+Ν) B(D+S → Φπ+), Cleo Collaboration, F. Butler, Manoj Thulasidas Mar 1994

A Measurement Of B(D+S → Φl+Ν) B(D+S → Φπ+), Cleo Collaboration, F. Butler, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

Using the CLEO II detector at CESR, we have measured the ratio of branching fractions B(D → φlν) B(D → φπ) = 0.54 ± 0.05 ± 0.04. We use this measurement to obtain a model dependent estimate of B(D → φπ). © 1994.


A Semantic Framework For Understanding The Behavior Of Modules And Classes In Programming Languages, Mahesh Dodani, Benjamin Kok Siew Gan Jan 1994

A Semantic Framework For Understanding The Behavior Of Modules And Classes In Programming Languages, Mahesh Dodani, Benjamin Kok Siew Gan

Research Collection School Of Computing and Information Systems

Recent trends in programming language design and implementation are aimed at integrating the two most important constructs to combat complexity: modules and classes. Both constructs provide encapsulation, a cornerstone of reliable programming. These constructs differ in their approach to building hierarchies: modules define visibility of components while classes define visibility of functionality. How can modules and classes be effectively integrated within a simple programming language? This question captures the essence of developing semantics of these constructs to ensure that they interact in a meaningful way. This paper develops a formal denotational semantic framework for understanding the interaction between classes and …


Measurement Of The Cross Section For Γγ→Pp̄, Artuso, M.; Et Al., M. Thulasidas Jan 1994

Measurement Of The Cross Section For Γγ→Pp̄, Artuso, M.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.


Resolving Attribute Incompatibility In Database Integration: An Evidential Reasoning Approach, Ee-Peng Lim, Shashi Shekhar Jan 1994

Resolving Attribute Incompatibility In Database Integration: An Evidential Reasoning Approach, Ee-Peng Lim, Shashi Shekhar

Research Collection School Of Computing and Information Systems

Resolving domain incompatibility among independently developed databases often involves uncertain information. DeMichiel (1989) showed that uncertain information can be generated by the mapping of conflicting attributes to a common domain, based on some domain knowledge. The authors show that uncertain information can also arise when the database integration process requires information not directly represented in the component databases, but can be obtained through some summary of data. They therefore propose an extended relational model based on Dempster-Shafer theory of evidence (1976) to incorporate such uncertain knowledge about the source databases. They also develop a full set of extended relational operations …


Exclusive Hadronic B Decays To Charm And Charmonium Final States, Alam, M.; Et Al., M. Thulasidas Jan 1994

Exclusive Hadronic B Decays To Charm And Charmonium Final States, Alam, M.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

We have fully reconstructed decays of both B¯0 and B− mesons into final states containing either D, D*, D**, ψ, ψ’, or χc1 mesons. This allows us to obtain new results on many physics topics including branching ratios, tests of the factorization hypothesis, color suppression, resonant substructure, and the B−−B¯0 mass difference.


Measurement Of Cabibbo-Suppressed Decays Of The Τ Lepton, Battle, M.; Et Al., M. Thulasidas Jan 1994

Measurement Of Cabibbo-Suppressed Decays Of The Τ Lepton, Battle, M.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.


Measurement Of The Branching Fraction For D+K-++, Balest, R.; Et Al., M. Thulasidas Jan 1994

Measurement Of The Branching Fraction For D+K-++, Balest, R.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

Using the CLEO II detector at the Cornell Electron Storage Ring we have measured the ratio of branching fractions, B(D+K-++)/(D0K-+)=2.350.160.16. Our recent measurement of scrB(D0K-+) then gives scrB(D+K-++)=(9.30.60.8)%.


Study Of The Five-Charged-Pion Decay Of The Τ Lepton, D. Gibaut, Manoj Thulasidas Jan 1994

Study Of The Five-Charged-Pion Decay Of The Τ Lepton, D. Gibaut, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

The branching fractions for the five-charged-particle decays of the τ lepton have been measured in e+e− annihilations using the CLEO II detector at the Cornell Electron Storage Ring. Assuming all charged particles to be pions, the results are B(3π−2π+≥0 neutrals ντ)=(0.097±0.005±0.011)%, B(3π−2π+ντ)=(0.077±0.005 ±0.009)%, B(3π−2π+π0ντ)=(0.019±0.004±0.004)%, and B(3π−2π+2π0ντ)B(3π−2π−π0ντ) is measured for the first time by exclusive π0 reconstruction. The results are compared with the predictions from the partially conserved-axial-current and conserved-vector-current hypotheses assuming isospin invariance.


Observation Of A New Charmed Strange Meson, Kubota, Y.; Et Al., M. Thulasidas Jan 1994

Observation Of A New Charmed Strange Meson, Kubota, Y.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.


Precision Measurement Of The Ds*+-Ds+ Mass Difference, Brown, D.; Et Al., M. Thulasidas Jan 1994

Precision Measurement Of The Ds*+-Ds+ Mass Difference, Brown, D.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

We have measured the vector-pseudoscalar mass splitting M(D*+s)-M(D+s)=144.22±0.47±0.37 MeV significantly more precisely than the previous world average. We minimize the systematic errors by also measuring the vector-pseudoscalar mass difference M(D*0)-M(D0) using the radiative decay D*0→D0γ, obtaining [M(D*+s)-M(D+s)]-[M(D*0)-M(D0)] =2.09±0.47±0.37 MeV. This is then combined with our previous high-precision measurement of M(D*0)-M(D0), which used the decay D*0→D0π0. We also measure the mass difference M(D+s)-M(D+)=99.5±0.6±0.3 MeV, using the φπ+ decay modes of the D+s and D+ mesons.


On The Equivalence Of Mceliece's And Niederreiter's Public-Key Cryptosystems, Y. X. Li, Robert H. Deng, X. M. Wang Jan 1994

On The Equivalence Of Mceliece's And Niederreiter's Public-Key Cryptosystems, Y. X. Li, Robert H. Deng, X. M. Wang

Research Collection School Of Computing and Information Systems

It is shown that McEliece's and Niederreiter's public-key cryptosystems are equivalent when set up for corresponding choices of parameters. A security analysis for the two systems based on this equivalence observation, is presented


Identifying Faces Using Multiple Retrievals, Jian Kang Wu, Arcot Desai Narasimhalu Jan 1994

Identifying Faces Using Multiple Retrievals, Jian Kang Wu, Arcot Desai Narasimhalu

Research Collection School Of Computing and Information Systems

During a police investigation, officers often have to sort through hundreds of photographs to identify a suspect. To aid this task, we at the Institute of Systems Science developed and implemented a flexible database system that can retrieve faces using personal information, fuzzy and free-text descriptors, and classification trees.


Observation Of Inclusive B Decays To The Charmed Baryons C++ And C0, Procario, M.; Te Al., M. Thulasidas Jan 1994

Observation Of Inclusive B Decays To The Charmed Baryons C++ And C0, Procario, M.; Te Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.


A Probabilistic Approach To Fault Diagnosis In Linear Lightwave Networks, Robert H. Deng, A. A. Lazar, W. Wang Dec 1993

A Probabilistic Approach To Fault Diagnosis In Linear Lightwave Networks, Robert H. Deng, A. A. Lazar, W. Wang

Research Collection School Of Computing and Information Systems

The application of probabilistic reasoning to fault diagnosis in linear lightwave networks (LLNs) is investigated. The LLN inference model is represented by a Bayesian network (or causal network). An inference algorithm is proposed that is capable of conducting fault diagnosis (inference) with incomplete evidence and on an interactive basis. Two belief updating algorithms are presented which are used by the inference algorithm for performing fault diagnosis. The first belief updating algorithm is a simplified version of the one proposed by Pearl (1988) for singly connected inference models. The second belief updating algorithm applies to multiply connected inference models and is …


Asynchronous Transaction Commitment In Federated Database Systems, San-Yih Hwang, Ee Peng Lim, Jaideep Srivastava Dec 1993

Asynchronous Transaction Commitment In Federated Database Systems, San-Yih Hwang, Ee Peng Lim, Jaideep Srivastava

Research Collection School Of Computing and Information Systems

We propose a new (and restricted) model for global transactions which allows asynchronous commitment of subtransactions. Our model requires each global transaction to have a fixed structure with update to the data in at most one database. Based on this transaction model, we present two concurrency control algorithms, namely Asynchronous Site Graph and Asynchronous VirtGlobalSG, which employ asynchronous commitment and achieve global serializability. Compared to other proposed algorithms, our algorithms employ asynchronous commitment so as to increase transaction performance. Furthermore, our algorithms do not put restrictions on transaction data access or local histories.


Dynamic Decision Modeling In Medicine: A Critique Of Existing Formalisms, Tze-Yun Leong Dec 1993

Dynamic Decision Modeling In Medicine: A Critique Of Existing Formalisms, Tze-Yun Leong

Research Collection School Of Computing and Information Systems

Dynamic decision models are frameworks for modeling and solving decision problems that take into explicit account the effects of time. These formalisms are based on structural and semantical extensions of conventional decision models, e.g., decision trees and influence diagrams, with the mathematical definitions of finite-state semi-Markov processes. This paper identifies the common theoretical basis of existing dynamic decision modeling formalisms, and compares and contrasts their applicability and efficiency. It also argues that a subclass of such dynamic decision problems can be formulated and solved more effectively with non-graphical techniques. Some insights gained from this exercise on automating the dynamic decision …


An Adaptive Coding Scheme With Code Combining For Mobile Radio Systems, Robert H. Deng, Huafei Zhou Nov 1993

An Adaptive Coding Scheme With Code Combining For Mobile Radio Systems, Robert H. Deng, Huafei Zhou

Research Collection School Of Computing and Information Systems

The authors propose and study an adaptive error-control coding scheme for binary digital FM (BFM) mobile radio transmission. The scheme employs code combining through packet retransmissions. The number of transmissions of a packet is in proportion to the channel fading/noise levels, which is in contrast to time diversity techniques where a fixed number of repetitions of a data packet is performed even in the absence of channel errors. Furthermore, the receiver uses received signal envelopes as channel state information, which significantly improves the throughput and bit error rate (BER) performance. Performance of the proposed scheme is analyzed for frequency-flat Rayleigh …


Multiple Query Optimization With Depth-First Branch-And-Bound, Ahmet Cosar, Ee Peng Lim, Jaideep Srivastava Nov 1993

Multiple Query Optimization With Depth-First Branch-And-Bound, Ahmet Cosar, Ee Peng Lim, Jaideep Srivastava

Research Collection School Of Computing and Information Systems

In certain database applications such as deductive databases, batch query processing, and recursive query processing etc., a single query can be transformed into a set ofclosely related database queries. Great benefits can be obtained by executing a group of related queries all together in a single unijied multi-plan instead of executing each query separately. In order to achieve this, Multiple Query Optimization (MQO) identifies common task(s) (e.g. common subezpressions, joins, etc.) among a set of query plans and creates a single unified plan (multiplan) which can be executed to obtain the required outputs forall queries at once. In this paper, …


Query Optimization And Processing In Federated Database Systems, Ee Peng Lim, Jaideep Srivastava Nov 1993

Query Optimization And Processing In Federated Database Systems, Ee Peng Lim, Jaideep Srivastava

Research Collection School Of Computing and Information Systems

No abstract provided.


Hybrid Arq Schemes For Point-To-Multipoint Communications Over Nonstationary Broadcast Channels, Robert H. Deng Sep 1993

Hybrid Arq Schemes For Point-To-Multipoint Communications Over Nonstationary Broadcast Channels, Robert H. Deng

Research Collection School Of Computing and Information Systems

Hybrid automatic-repeat-request (ARQ) error control schemes make use of both error detection and error correction in order to achieve high throughput and low undetected error probabilities on two way channels. Two hybrid ARQ schemes, termed hybrid go-back-N (HGB- N) and hybrid selective-repeat (HSR), are proposed for point-to-multipoint communications over broadcast channels. Both schemes incorporate a concatenated code for error correction and error detection. The performance study of the hybrid schemes is based on a two-state Markov model of a burst noise channel. An analytic solution is derived for the throughput efficiency of the HSR scheme, while approximations and computer simulation …


Entity Identification In Database Integration: An Evidential Reasoning Approach, Ee Peng Lim, Jaideep Srivastava Sep 1993

Entity Identification In Database Integration: An Evidential Reasoning Approach, Ee Peng Lim, Jaideep Srivastava

Research Collection School Of Computing and Information Systems

Entity identification is the problem of matching object instances from different databases which correspond to the same real-world entity. In this paper, we present a 2-step entity identification process in which attributes for matching tuples may be missing in certain tuples, and thus need to be derived prior to the matching. To match tuples, we require identity rules which specify the conditions to be satisfied by a pair of tuples, from different databases, before they can be considered as modeling the same real-world entity. We also introduce ILFD's (instance-level functional dependencies) as a form of inference rules which derive the …


Two Measurements Of B0 B-0 Mixing, J. Bartelt, Manoj Thulasidas Sep 1993

Two Measurements Of B0 B-0 Mixing, J. Bartelt, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

We have measured the B0B¯0 mixing probability, χd, using a sample of 965 000 BB¯ pairs from Υ(4S) decays. Counting dilepton events, we find χd=0.157±0.016±0.018+0.028−0.021. Using tagged B0 events, we find χd=0.149±0.023±0.019±0.010. The first (second) error is statistical (systematic). The third error reflects a ±15% uncertainty in the assumption, made in both cases, that charged and neutral B pairs contribute equally to dilepton events. We also obtain a limit on the CP impurity in the B0d system, ‖Re(ε0B)‖


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.


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 …


Performance Analysis Of Two Bridged Csma/Cd Networks, C. C. Ko, W. C. Wang, J. L. Du, Robert H. Deng, K. M. Lye Aug 1993

Performance Analysis Of Two Bridged Csma/Cd Networks, C. C. Ko, W. C. Wang, J. L. Du, Robert H. Deng, K. M. Lye

Research Collection School Of Computing and Information Systems

This paper analyses the performance of two non-persistent CSMA/CD LANs linked by a bridge. The main function of the bridge is to buffer all internet work packets and forward them across networks to their destinations. From establishing and solving the main equations governing the behaviour of the bridged networks, the effects of design parameters such as the bridge buffer size and re-transmission back off delay on the performance of the system are studied. It is shown that if these parameters are chosen properly, better throughput and delay performance can be obtained, when compared with an equivalent CSMA/CD network without using …


Facial Image Retrieval, Identification, And Inference System, Jian Kang Wu, Yew Hock Ang, Chiam Prong Lam, S. K. Moorthy, Arcot Desai Narasimhalu Aug 1993

Facial Image Retrieval, Identification, And Inference System, Jian Kang Wu, Yew Hock Ang, Chiam Prong Lam, S. K. Moorthy, Arcot Desai Narasimhalu

Research Collection School Of Computing and Information Systems

Recognition of a human face is very easy even to a child, but is extremely difficult for computers. Here we present a Computer Aided Facial Image Identification, Retrieval and Inference System (CAFIIRIS) for criminal identification. The system stores and manages facial images and criminal records, providing necessary image and text processing, and editing tools. Inference of facial images of different ages of a person is also possible. Access to facial images can be done via key words, fuzzy descriptions, and visual browsing.


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 …


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 …


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 …