15495414
A tool based methodology for development of automatically scalable and reusable parallel code
Program performance may be improved by efficiently programming some key sections of the software. We present a methodology for converting selected portions of source code into automatically scalable multithreaded routines, without forcing programmers to concentrate on parallel programming issues. These developed routines can be reused across various projects, operating systems and system architectures. To support this methodology two separate but tightly coupled tools have been developed -PARSA/sup (TM)/ software development environment (SDE) and the ThreadMan/sup (TM)/ thread manager. The SDE addresses programming issues by allowing a graphical object based approach to develop multithreaded routines that abstracts the users from parallel programming. ThreadMan manages the software developed using SDE. ThreadMan is a user-level thread manager that automatically spawns and schedules threads at runtime. Two examples have been developed using this methodology to demonstrate that there is virtually no degradation in performance when compared to sequential code, in a single processor system and scalability is achieved as the number of processors is increased.
376625
Mobile Agents for Pervasive Computing Using a Novel Method of Message Passing
Pervasive computing is an emerging technology that brings new dimensions to distributed computing; it uses a wide variety of smart, ubiquitous devices throughout an individual’s working and living environment. Mobile agents are software entities that can migrate between servers or mobile agent environments of the network accomplishing various tasks on the behalf of their owners. The objective of this paper is to describe a test and prototyping environment for experimenting with mobile agents in pervasive environments. A prototype environment for a novel proactive infrastructure is described for mobile agent assisted pervasive computing. In addition, a new message passing algorithm is provided for mobile agent connection establishment and management (CEMA).
30423936
A scalable and self-adapting notification framework for healthcare information systems
There has been a great interest in publish/subscribe systems in recent years. This interest, coupled with the pervasiveness of lightweight electronic devices, such as cellular phones and PDAs, have opened a new arena in publish/subscribe networks. Currently, many broker overlay networks are static and never change in structure. Often, a network overlay structure is predefined or manually manipulated. We present a dynamic broker network in the context of disseminating critical labs and patient information in a Healthcare Information System (HIS). Our work builds upon previous network optimization research on ad-hoc publish/subscribe networks. Our framework utilizes user-defined heuristic cost functions to satisfy QoS constraints. We also address certain reliability issues by providing a scheduling algorithm to selectively retransmit information.
11624555
A Query Algebra for Fragmented XML Stream Data
The increased usage of mobile devices coupled with an unprecedented demand for information has pushed the scalability problem of pull-based data service to the focus. A broadcast model of streaming data over a wireless medium has been proposed as a viable alternative for information dissemination. In the streaming broadcast model, servers broadcast data in an asynchronous and unacknowledged mode while clients process personalized and complex queries locally, relieving the load on the server. We address the query processing of streamed XML data, which is fragmented into manageable chunks for easier synchronization. Although there has been some work done in defining algebras that model XQueries on XML documents, no work has been done in defining query algebras for fragmented XML stream data. We define a model for processing fragmented XML stream data, using the concept of holes and fillers. This model offers the flexibility required by the server to disseminate data in manageable fragments, whenever they become available, and to send repetitions, replacements and removal of fragments. We then present a query algebra for XQuery that operates on this streamed XML data model. The XML fragments are operated upon in a continuous pipelined fashion without the need of materializing the transmitted document at the client site.
13161865
On the Reliability and Additional Overhead of Reliable On-Demand Multicast Routing Protocol for Mobile Ad Hoc Networks
Multicasting is the transmission of datagrams to a group of hosts identified by a single destination address, providing simple and efficient communication for group-oriented applications. Many applications currently envisioned for mobile ad hoc networks require multicasting. Several multicasting protocols have been proposed for mobile ad hoc networks, one of the most popular being the On Demand Multicast Routing Protocol. This paper provides a review of ad hoc multicast routing protocols, focusing on MAODV, ODMRP and a variation of ODMRP called reliable-ODMRP. NS-2 simulations are used to compare the reliability and overhead of MAODV, ODMRP, and R-ODMRP.
36810175
A Multimedia Application using Mobile Agents for Establishing and Managing Streaming Audio Communications
Objective To be a part of an academic institution which has a strong and dedicated commitment to quality education and research.  Built a new UNIX Sun workstation network lab for the CS department. The lab is used for courses, mail and web service.
207225786
Genetic Algorithms: A Practitioner's View
The feature article by Colin Reeves provides a useful introduction to genetic algorithms (GAs) for the operations researcher. In this commentary, I will elaborate on several of Reeves' points and introduce some others. My experience with GAs is as a practitioner and software developer, and it is from this perspective that I will comment on Reeves' article.
29157947
Massively parallel computation of conservation laws
Abstract We present a new method for computing solutions of conservation laws based on the use of cellular automata with the method of characteristics. The method exploits the high degree of parallelism available with cellular automata and retains important features of the method of characteristics. It yields high numerical accuracy and extends naturally to adaptive meshes and domain decomposition methods for perturbed conservation laws. We describe the method and its implementation for a Dirichlet problem with a single conservation law for the one-dimensional case. Numerical results for the one-dimensional law with the classical Burgers nonlinearity or the Buckley-Leverett equation show good numerical accuracy outside the neighborhood of the shocks. The error in the area of the shocks is of the order of the mesh size. The algorithm is well suited for execution on both massively parallel computers and vector machines. We present timing results for an Alliant FX/8, Connection Machine Model 2, and CRAY X-MP.
16053840
Parallel computation of three-dimensional nonlinear magnetostatic problems
We describe a general-purpose parallel electromagnetic code for computing accurate solutions to large computationally demanding, 3D, nonlinear magnetostatic problems. The code, CORAL, is based on a volume integral equation formulation. Using an IBM SP parallel computer and iterative solution methods, we successfully solved the dense linear systems inherent in such formulations. A key component of our work was the use of the PETSc library, which provides parallel portability and access to the latest linear algebra solution technology.
206967153
Iterative Joint Source-Channel Decoding of H.264 Compressed Video
This paper proposes an iterative joint source-channel decoding (IJSCD) scheme for the transmission of H.264 compressed video over a noisy channel. It uses channel coding along with H.264 semantic verification. The structure, selection of design parameters, and performance of the proposed IJSCD based on a rate-% recursive systematic convolutional (RSC) code over an AWGN channel are described and discussed as an illustrative example. In the example, for the same PSNR, the proposed IJSCD scheme offers a significant saving of 2.1dB in required channel SNR as compared to a system using the same RSC code alone. Furthermore, the performance can be improved by iterative decoding at the cost of increased delay. Hence, a tradeoff can be made between performance improvement and delay
24464091
Contours of constructive hypertexts
Discussion of hypertext rhetoric and criticism has foeused on small, freed hypertext that am typically used by casual readers for comparatively short periods. Here we explo~ complex, constructive hypertext, intended to inform and to infIuence dedicated and thoughtful readers. Recurrence and multivalence, both deplored in small hypertext, prove from study of mom complex texts to be very valuable. While static, graph-theoretic measures facilitate understanding of Ioeal hypertext structure, the structures of meaning or contours we observe in current hypertext fiction and scholarship do not appear to reside in static structures, but rather in the complex and dynamic perceptions of the engagedreader.