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Research Collection School Of Computing and Information Systems

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Full-Text Articles in Software Engineering

The Window Distribution Of Multiple Tcps With Random Loss Queues, Archan Misra, Teunis Ott, John Baras Dec 1999

The Window Distribution Of Multiple Tcps With Random Loss Queues, Archan Misra, Teunis Ott, John Baras

Research Collection School Of Computing and Information Systems

Two approximate techniques for analyzing the window size distribution of TCP flows sharing a RED-like bottleneck queue are presented. Both methods presented first use a fixed point algorithm to obtain the mean window sizes of the flows, and the mean queue length in the bottleneck buffer. The simpler of the two methods then uses the ‘square root formula’ for TCP; the other method is more complicated. More often than not, the simpler method is slightly more accurate; this is probably due to the fact that window sizes of the different flows are negatively correlated.


Mpeg-4 Systems And Applications, Hari Kalva, Lai-Tee Cheok, Alexandros Eleftheriadis Nov 1999

Mpeg-4 Systems And Applications, Hari Kalva, Lai-Tee Cheok, Alexandros Eleftheriadis

Research Collection School Of Computing and Information Systems

MPEG-4, under the auspices of the ISO, is specifying tools to enable object-based audio-visual presentations [3]. These include tools to encode individual objects, compose presentations with objects, store these object-based presentations and access these presentations in a distributed manner over networks. The main distinguishing feature of object-based audio-visual presentations is the scene composition at the user terminal. The objects that are part of a scene are composed and displayed at the user end as opposed to encoding the composed scenes as is done in the case of MPEG-2. Such object-based representation and presentation has several benefits including compression efficiency and …


Design Approaches To Model-Based Simulation In Intelligent Computer Assisted Instruction, Bjoern Helfesrieder, Venky Shankararaman Sep 1999

Design Approaches To Model-Based Simulation In Intelligent Computer Assisted Instruction, Bjoern Helfesrieder, Venky Shankararaman

Research Collection School Of Computing and Information Systems

Model-based simulation systems have been created in various fields of engineering to train personnel or students in operation, maintenance and troubleshooting of complex devices and systems. A review of literature indicates a lack of good overviews of the approaches to system design of model-based training simulations in Intelligent Computer Assisted Instruction (ICAI). Though single systems have to some extent been evaluated with regard to their performance, an organised evaluation, especially a comparative evaluation of the systems that have been created within the field is lacking. To be able to successfully conduct an in-depth review under these conditions, we concentrate and …


Xcert Software, Inc., Keng Siau Sep 1999

Xcert Software, Inc., Keng Siau

Research Collection School Of Computing and Information Systems

Xcert’s business is in developing Internet and Intranet security enhancement technology. Xcert was founded in April 1996 by Andrew Csinger and Pat Richard and was headquartered in Vancouver, Canada. Xcert’s solution to Internet security was a public key infrastructure (PKI). PKI is a system of digital certi® cates, certi® cate authorities (CAs) and other registration authorities that verify and authenticate the validity of each party involved in an Internet transaction. Xcert’s PKI technology allows organizations of any size to issue digital certi® cates to their members. These organizations become their own CA and are empowered to issue digital certi® cates …


Notepals: Lightweight Note Sharing By The Group, For The Group, Richard C. Davis, James A. Landay, Victor Chen, Jonathan Huang, Rebecca B. Lee, Francis Li, James Lin, Charles B. Morrey, Morgan N. Price, Bill N. Schilit May 1999

Notepals: Lightweight Note Sharing By The Group, For The Group, Richard C. Davis, James A. Landay, Victor Chen, Jonathan Huang, Rebecca B. Lee, Francis Li, James Lin, Charles B. Morrey, Morgan N. Price, Bill N. Schilit

Research Collection School Of Computing and Information Systems

NotePals is a lightweight note sharing system that gives group members easy access to each others experiences through their personal notes. The system allows notes taken by group members in any context to be uploaded to a shared repository. Group members view these notes with browsers that allow them to retrieve all notes taken in a given context or to access notes from other related notes or documents. This is possible because NotePals records the context in which each note is created (e.g., its author, subject, and creation time). The system is lightweight because it fits easily into group members …


The Window Distribution Of Idealized Tcp Congestion Avoidance With Variable Packet Loss, Archan Misra, Teunis J. Ott Mar 1999

The Window Distribution Of Idealized Tcp Congestion Avoidance With Variable Packet Loss, Archan Misra, Teunis J. Ott

Research Collection School Of Computing and Information Systems

This paper analyzes the stationary behavior of the TCP congestion window performing ideal congestion avoidance when the packet loss probability is not constant, but varies as a function of the window size. By neglecting the detailed window behavior during fast recovery, we are able to derive a Markov process that is then approximated by a continuous-time, continuous state space process. The stationary distribution of this process is analyzed and derived numerically and then extrapolated to obtain the stationary distribution of the TCP window. This numerical analysis enables us to predict the behavior of the TCP congestion window when interacting with …


Making Sharing Pervasive: Ubiquitous Computing For Shared Note Taking, James A. Landay, Richard C. Davis Jan 1999

Making Sharing Pervasive: Ubiquitous Computing For Shared Note Taking, James A. Landay, Richard C. Davis

Research Collection School Of Computing and Information Systems

As a variety of low-cost note-taking devices becomes pervasive, shared notes can help work groups better communicate ideas and information. To explore this idea further, we carried out three related case studies of how members of a large research group shared meeting notes. The group found value in combining personal notes and presentation slides with a single, unifying document, such as regular meeting minutes. The minutes provided structure when there were too many sources of notes. We used this insight in our design of NotePals, a note-sharing system with a lightweight process, an interface, and hardware that distinguish it from …


Xcert Software, Inc., Keng Siau Dec 1998

Xcert Software, Inc., Keng Siau

Research Collection School Of Computing and Information Systems

The case on Xcert Software, Inc., illustrates the operational and strategic issues encountered by a startup IT company in the Internet security business. Xcert faces difficulty in a number of areas: (1) finances, (2) future direction and leadership, (3) organizational structure, experience and size, and (4) marketing. This is a discussion case that introduces students to the competitive world of Internet business and provides them an opportunity to discuss and debate the myriad issues facing the founders of Xcert.


Notepals: Sharing And Synchronizing Handwritten Notes With Multimedia Documents, James A. Landay, Richard C. Davis, Victor Chen, Jonathan Huang, Rebecca B. Lee, Francis Li, James Lin, Charles B. Morrey, Ben Schleimer Nov 1998

Notepals: Sharing And Synchronizing Handwritten Notes With Multimedia Documents, James A. Landay, Richard C. Davis, Victor Chen, Jonathan Huang, Rebecca B. Lee, Francis Li, James Lin, Charles B. Morrey, Ben Schleimer

Research Collection School Of Computing and Information Systems

NotePals is an ink-based, collaborative note taking application that runs on personal digital assistants (PDAs). Meeting participants write notes in their own handwriting on a PDA. These notes are shared with other participants by synchronizing later with a shared note repository that can be viewed using a desktop-based web browser. NotePals is distinguished by its lightweight process, interface, and hardware. This demonstration illustrates the design of two different NotePals clients and our web-based note browser.


A Framework For Sharing Handwritten Notes, Richard C. Davis, James Lin, Jason A. Brotherton, James A. Landay, Morgan N. Price, Bill N. Schilit Nov 1998

A Framework For Sharing Handwritten Notes, Richard C. Davis, James Lin, Jason A. Brotherton, James A. Landay, Morgan N. Price, Bill N. Schilit

Research Collection School Of Computing and Information Systems

NotePals is an ink-based, collaborative note taking application that runs on personal digital assistants (PDAs). Meeting participants write notes in their own handwriting on a PDA. These notes are shared with other participants by synchronizing later with a shared note repository that can be viewed using a desktop-based web browser. NotePals is distinguished by its lightweight process, interface, and hardware. This demonstration illustrates the design of two different NotePals clients and our web-based note browser.


Multiple Representation For Understanding Data Structures, Biffah Hancies, Venky Shankararaman, Jose Munoz Aug 1997

Multiple Representation For Understanding Data Structures, Biffah Hancies, Venky Shankararaman, Jose Munoz

Research Collection School Of Computing and Information Systems

In this paper an approach to enhance the learning of abstract computing concepts by novice students is presented. This approach is based on effective use of multiple visual representations, and it was applied within the domain of linear data structures: array, stack, queue and linked list. A prototype computer-based instructional system called MRUDS (Multiple Representation for Understanding Data Structures) was developed and evaluated. It was found from the evaluation that the three presentation modules namely, analogy, representation and algorithm contributed to the students' learning process, each contributing to and reinforcing the effect of the others.


Report On The 5th Ifip International Workshop On Quality Of Service, Oguz Angin, Andrew T. Campbell, Lai Tee Cheok, Raymond Liao, Koon-Seng Lim, Klara Nahrstedt Jul 1997

Report On The 5th Ifip International Workshop On Quality Of Service, Oguz Angin, Andrew T. Campbell, Lai Tee Cheok, Raymond Liao, Koon-Seng Lim, Klara Nahrstedt

Research Collection School Of Computing and Information Systems

This paper presents a summary of the fifth International Workshop on Quality of Service (IWQOS) which was held at Columbia University in May 1997. The goal of this three-day meeting was to foster interaction between researchers active in the area of Quality of Service(QOS) research, to reflect on past experiences and lessons learnt, and to discuss future QOS challenges. To reflect this goal, this year's workshop included a hot program made up of (i) a keynote address on "Programming Telecommunications Networks"; (ii) panels addressing "QOS for Distributed Object Computing Middleware --- Fact or Fiction?" and "Reservations about Reservations"; (iii) a …


Object Interactions As First Class Objects: From Design To Implementation, Mahesh Dodani, Benjamin Kok Siew Gan, Lizette Velazquez Jan 1995

Object Interactions As First Class Objects: From Design To Implementation, Mahesh Dodani, Benjamin Kok Siew Gan, Lizette Velazquez

Research Collection School Of Computing and Information Systems

Collaborations between objects make up the dynamic behavior of OO software. These collaborations among objects require careful design and implementation. Treating the interactions as responsibilities that are integrated in the participating objects, results in tight coupling between objects. Tight coupling increases complexity and reduces reusability. Object interactions need to be first class objects from design to implementation. Our research provides a unified approach to model and implement these interactions as first class objects. During analysis and design, they are modeled using DynaSpecs. During implementation, they are coded with a new language construct called Compositions. DynaSpecs and Compositions provide a consistent …


Knowledge-Based Safety Training System (Kbsts): A Prototype Implementation, Venky Shankararaman, B. S. Lee Dec 1994

Knowledge-Based Safety Training System (Kbsts): A Prototype Implementation, Venky Shankararaman, B. S. Lee

Research Collection School Of Computing and Information Systems

A computer-based safety training system for process operators must be able to make effective presentation of textual material, test the trainee's understanding through quizzes and facilitate plant simulation. The general framework of such a system is presented in an earlier paper (Computers in Industry, Vol. 17, 1991, pp. 349–358). In this paper, we discuss the development and implementation of a prototype Knowledge-Based Safety Training System based on the framework. The design philosophy, system architecture and the plant modelling methodology are described.


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 …


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


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.


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.


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 …