33039704
A circular skip-cluster scheme to support video-on-demand services
Abstract. The major drawback of the existing cluster placement scheme is the long response time caused by admission control if the number of clusters and the number of users are large. A circular skip-cluster placement scheme is proposed to reduce the size of the data buffer as well as the system response time. Furthermore, the popularity of each video is different in the real world. We propose a new popularity-based data allocation scheme to allocate data units within a cluster such that the corresponding data units of these popular videos are stored in those cylinders at one end of each cluster. Due to a higher spatial locality within these hot cylinders, some data units requested by the users are stored in the same cylinder such that one seek operation, one rotation, and one transfer operation are required to retrieve these data units. Therefore, the time required to retrieve data for these requests can be reduced, thus also reducing the system response time. Based on our results, the buffer size and the system response time can be reduced by half or more. These findings are essential for constructing video-on-demand systems that provide satisfactory performance.
10317156
A research on Collaboration Net
We present research on computer-supported cooperative work by introducing an approach to the multimedia based net-centric conference environment-Collaboration Net. Some basic definitions of the distributed Web-based meeting are provided, and the properties of this kind of collaboration are given. We explain problems associated with the well-known yet old-fashioned parliamentary procedure, Robert's Rules of Order, which must be formally modeled and adapted to the modern net-centric virtual conference where time synchronism is hard to enforce. A prototype of our Web-browser based approach to developing the Collaboration Net is also briefly presented. Finally, research challenges in this area are highlighted.
8941164
Supporting agent-based distributed software development through modeling and simulation
In today's software engineering environment, it is becoming increasingly commonplace for team members and stakeholders to be distributed in multiple locations and time zones. Under these circumstances, the coordination of software development activities becomes increasingly more complex. One solution uses mobile agent-based tools to support collaborative software engineering tasks, such as requirements management. Despite the fact that development and validation of such tools would be facilitated by the use of modeling and simulation, very little work relating formal methods to agent-based system development has been performed. This paper therefore presents a hierarchical colored Petri Net (CPN) model as a formal framework for agent-based distributed software development, and demonstrates its usefulness by applying the framework to the development of a requirements management system.
18643244
An Empirical Performance Study on PSIM
It is well known that errors caught in the early stages of system development life cycle greatly helped reduce the expense for later error fixing and mitigate risks and complications. Performance analysis is one of the methods to ensure satisfactory system performance that can avoid redesign and patch in the later stage of system development when performance problems emerge. Much work has been done to address such concerns collectively known as the 'performance engineering' problem. However, a comprehensive method is still needed to provide an end-to-end support for performance evaluation on software architecture design. Automated tools to support the method must be developed, and its validation must be carefully planned and conducted. In response to this need, we propose our approach, PSIM (performance simulation and modeling). PSIM is a performance simulation and modeling tool that integrated performance properties into software architecture specifications expressed in several major UML diagrams. PSIM models can be transformed into Colored GSPN (colored generalized stochastic Petri nets) via an automated tool. As a result, the Colored GSPN models can be simulated to perform model-based performance evaluation. In this paper PSIM is first briefly reviewed and illustrated through modeling a web-based electronic conferencing system, called M-Net, to derive performance metrics. We then conduct runtime performance testing to the implementation of M-Net and compare the simulation results against the runtime testing data. PSIM is shown to be effective in predicting system performance and in identifying system performance bottlenecks through this experimentation.
1871945
Specifications in software prototyping
Abstract We explore the use of software specifications for software prototyping. This paper describes a process model for software prototyping, and shows how specifications can be used to support such a process via a cellular mobile phone switch example.
15614662
Towards increasing web application productivity
In this paper we present and discuss a template/meta-data based partial code generation system supporting web application development. Seamlessly incorporating the recent top-notch technologies, the framework maximally exploits the capabilities of the underlying implementation technologies. Our approach primarily benefits the framework and code developers. In addition, the complete separation of data model, navigation model, and presentation model reflects on a more general conceptual process that would decouple the technique and methodology from its underlying technology choices. The decoupling between the generated code and the code that is necessarily added later on through other development pathways than the generator deals with the incremental changes and adaptations of the models in the face of an operational system, therefore further enhances the extensibility, maintainability, and reusability of the generated applications.
33610290
Biomimetic Robotics
6352215
Reconfigurable Web wrapper agents for biological information integration
A variety of biological data is transferred and exchanged in overwhelming volumes on the World Wide Web. How to rapidly capture, utilize, and integrate the information on the Internet to discover valuable biological knowledge is one of the most critical issues in bioinformatics. Many information integration systems have been proposed for integrating biological data. These systems usually rely on an intermediate software layer called wrappers to access connected information sources. Wrapper construction for Web data sources is often specially hand coded to accommodate the differences between each Web site. However, programming a Web wrapper requires substantial programming skill, and is time-consuming and hard to maintain. In this article we provide a solution for rapidly building software agents that can serve as Web wrappers for biological information integration. We define an eXtensible Markup Language (XML)-based language called Web Navigation Description Language (WNDL), to model a Web-browsing session. A WNDL script describes how to locate the data, extract the data, and combine the data. By executing different WNDL scripts, we can automate virtually all types of Web-browsing sessions. We also describe IEPAD (Information Extraction Based on Pattern Discovery), a data extractor based on pattern discovery techniques. IEPAD allows our software agents to automatically discover the extraction rules to extract the contents of a structurally formatted Web page. With a programming-by-example authoring tool, a user can generate a complete Web wrapper agent by browsing the target Web sites. We built a variety of biological applications to demonstrate the feasibility of our approach.
21116848
Optimal 1-edge fault-tolerant designs for ladders
A graph G* is 1-edge fault-tolerant with respect to a graph G, denoted by 1-EFT(G), if every graph obtained by removing any edge from G* contains G. A 1-EFT(G) graph is optimal if it contains the minimum number of edges among all 1-EFT(G) graphs. The kth ladder graph, Lk, is defined to be the cartesian product of the Pk and P2 where Pn is the n-vertex path graph. In this paper, we present several 1-edge fault-tolerant graphs with respect to ladders. Some of these graphs are proven to be optimal.
1786671
Light field compression using disparity-compensated lifting and shape adaptation
We propose disparity-compensated lifting for wavelet compression of light fields. With this approach, we obtain the benefits of wavelet coding, such as scalability in all dimensions, as well as superior compression performance. Additionally, the proposed approach solves the irreversibility limitations of previous light field wavelet coding approaches, using the lifting structure. Our scheme incorporates disparity compensation into the lifting structure for the transform across the views in the light field data set. Another transform is performed to exploit the coherence among neighboring pixels, followed by a modified SPIHT coder and rate-distortion optimized bitstream assembly. A view-sequencing algorithm is developed to organize the views for encoding. For light fields of an object, we propose to use shape adaptation to improve the compression efficiency and visual quality of the images. The necessary shape information is efficiently coded based on prediction from the existing geometry model. Experimental results show that the proposed scheme exhibits superior compression performance over existing light field compression techniques.
9268321
Online medical teaching case database
Case-based teaching allows for the study of medicine through records of patient encounters. These cases, used for teaching purposes, are variably collected by clinicians as hard copies of patient files and radiology films. Currently, a single repository of thorough, multi-disciplinary, medical teaching cases that can be uniformly accessed, shared, and searched comprehensively by all medical professionals does not exist. An Internet accessible database (iCORD) that focuses on graphical, audio-visual information along with text has been created. Users may create their own teaching case records to organize their files and share them with others. Case submissions are executed through a non-platform-specific application securely connected to the iCORD database. This submission tool and connector module, was developed using Java and XML-related technologies. The data storage medium, which is an extensible SQL database primarily used for storing patient case information, is exposed using IIS 5.0 and XML-based transformation tools to allow dynamic content delivery to PC's and handheld devices. Usage statistics, distributable teaching files, and user-centric information, which are compiled in the iCORD database, allow development of useful case search algorithms. The prototype database of 400 otolaryngology clinical cases is fully searchable using Boolean logic by parameters including age, gender, diagnosis, medical history, clinical keywords, pathology keywords, and more. The database can be used as a teaching tool during conferences and as a case authoring tool for physicians.