45515179
Distributed real-time nested transactions
Abstract We present the concepts of real-time nested transactions and priority propagation for a distributed transaction processing environment. Real-time nested transactions incorporate the deadline requirements in the hierarchical structure of nested transactions. Priority propagation addresses issues related to transaction aborts in real-time nested transaction processing. The notion of priority ceiling has been used to avoid the priority inversion problem. The proposed protocols exhibit freedom from deadlock and have tightly bounded waiting periods. Both of these properties make them very suitable for distributed real-time transaction processing environments.
8543519
Design and Implementation of National Engineering Education Delivery System
5516778
Bridges for Interconnection of Ring Networks: A Simulation Study
17876052
Probabilistic constructive optimization techniques
We have developed a new optimization paradigm for solving computationally intractable combinatorial optimization and synthesis problems. The technique, named probabilistic constructive, combines the advantages of both constructive and probabilistic optimization mechanisms. Since it is a constructive approach, it has a relatively short runtime and is amenable for the inclusion of insights through heuristic rules. The probabilistic nature facilitates a flexible tradeoff between runtime and the quality of solution, suitability for the superimposition of a variety of control strategies, and simplicity of implementation. After presenting the generic technique, we apply it to a generic NP-complete problem (maximum independent set) and a synthesis and compilation problem (sequential code covering). Extensive experimentation indicates that the new approach provides very attractive tradeoffs between the quality of solution and runtime, often outperforming the best previously published approaches.
35883623
Supporting organizational knowledge management with agents
Organizations are looking at ways to manage their information resources. Both the capture and the use of data created by the organization have come under scrutiny. Part of the concern comes from their desire to enhance the business process and part comes from the explosion of data available to any organization. In this context, the role of committees is being examined both as consumers and producers of information. The present work is focused on making the vast amount of unstructured text more useful to committees. An agent environment has been designed and implemented.
8690187
Distributed Simulation Using a Network of Processors
Abstract Simulation, particulary of networks of queues, is an application with a high degree of inherent parallelism and is of great practical interest. We hope to exploit this parallelism by performing simulations using a network of cheap, but slow, micro-processors. We define a taxonomy by which we classify a number of parameters of a distributed simulation method, and seek solutions to problems of synchronization, deadlock prevention and inter-process communication arising with various methods in each class of the taxonomy. We concentrate in particular on the class (loose, event-driven) which seems to possess the greatest potential parallelism, and on the class (scaled, tight, time-driven) which allows mock-up studies of real systems. We give algorithms for deadlock prevention and detection, and briefly discuss the design of a distributed operating system to support the simulation application. This research forms part of a joint program with the Dept. of Computer Sciences, University of Texas at Austin, directed by Prof. K.M. Chandy.
10377978
Scheduling of soft real-time systems for context-aware applications
Context-aware applications pose new challenges, including a need for new computational models, uncertainty management, and efficient optimization under uncertainty. Uncertainty can arise at two levels: multiple and single tasks. When a mobile user changes environments, the context changes resulting in the possibility of the user requesting tasks which are specific for the new environment. However as the user moves these requested tasks may no longer be context relevant. Additionally, the runtime of each task is often highly dependent on the input data. We introduce an hierarchical multi-resolution statistical task model that captures relevant aspects at the task and intertask levels, and captures not only uncertainty, but also introduces the notion of utility for the user. We have developed a system of nonparametric statistical techniques for modeling the runtime of a specific task. This model is a framework where we define problems of design and optimization of statistical soft real-time systems (SSRTS). The main algorithmic novelty is a cumulative potential-based task scheduling heuristic for maximizing utility. The heuristic conducts global optimization and induces low runtime overhead. We demonstrate the effectiveness of the scheduling heuristic using a Trimaran-based evaluation platform.