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- Performance evaluation (2)
- Bridge (1)
- CSMA/CD (1)
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- Distinctness rules (1)
- Distributed databases (1)
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- Extended key (1)
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- Federated Autonomous Databases (1)
- File transfer (1)
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Articles 1 - 25 of 25
Full-Text Articles in Physical Sciences and Mathematics
A Probabilistic Approach To Fault Diagnosis In Linear Lightwave Networks, Robert H. Deng, A. A. Lazar, W. Wang
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
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
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 …
Multiple Query Optimization With Depth-First Branch-And-Bound, Ahmet Cosar, Ee Peng Lim, Jaideep Srivastava
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, …
An Adaptive Coding Scheme With Code Combining For Mobile Radio Systems, Robert H. Deng, Huafei Zhou
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 …
Query Optimization And Processing In Federated Database Systems, Ee Peng Lim, Jaideep Srivastava
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
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
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 …
A Survey Of Expert Systems In Singapore And The Integration Of Multimedia Technology And Expert Systems, Arcot Desai Narasimhalu
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
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 …
Memory-Adaptive External Sorting, Hwee Hwa Pang, Michael J. Carey, Miron Livny
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.
Facial Image Retrieval, Identification, And Inference System, Jian Kang Wu, Yew Hock Ang, Chiam Prong Lam, S. K. Moorthy, Arcot Desai Narasimhalu
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 Analysis Of Interconnected Lans With Server/Client Configuration, Jiangling Du, Robert H. Deng, Chi Chung Ko
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
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
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 …
Federated Autonomous Databases: Project Overview, Satya Prabhakar, Jiandong Huang, James Richardson, Jaideep Srivastava, Ee Peng Lim, Sham Navathe, Ashok Savarase, Mark Foresti
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.
Entity Identification In Database Integration, Ee Peng Lim, Jaideep Srivastava, Satya Prabhakar, James Richardson
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 …
Repository Evaluation Of Software Reuse: An Empirical Study, R. D. Banker, Robert J. Kauffman, D. Zweig
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.
Search For Τ-→Γμ-: A Test Of Lepton Number Conservation, A. Bean, M. Thulasidas
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−)
Tau Decays With One Charged Particle Plus Multiple Π0'S, M. Procario, Manoj Thulasidas
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.
Measurement Of Charmless Semileptonic Decays Of B Mesons, Bartelt; J.; Et Al., M. Thulasidas
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.
Observation Of The Charmed Baryon C+ And Measurement Of The Isospin Mass Splittings Of The C, Crawford, G.; Et Al., M. Thulasidas
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.
Observation Of B0 Decay To Two Charmless Mesons, M. Battle, Manoj Thulasidas
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
Evidence For Penguin-Diagram Decays: First Observation Of B→K*(892)Γ, R. Ammar, M. Thulasidas
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.
Study Of D0 Decays Into K̄0 And K̄*0, M. Procario, M. Thulasidas
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.