45057698
The distributed program reliability analysis on star topologies
Abstract A distributed computing system consists of processing elements, communication links, memory units, data files, and programs. These resources are interconnected via a communication network and controlled by a distributed operating system. The distributed program reliability in a distributed computing system is the probability that a program which runs on multiple processing elements and needs to retrieve data files from other processing elements will be executed successfully. This reliability varies according to (1) the topology of the distributed computing system, (2) the reliability of the communication edges, (3) the data files and programs distribution among processing elements, and (4) the data files required to execute a program. In this paper, we show that computing the distributed program reliability on the star distributed computing systems is NP-hard. We also develop an efficiently solvable case to compute distributed program reliability when some additional file distribution is restricted on the star topology. Scope and purpose Recent advances in VLSI circuitry have a tremendous impact on the price-performance revolution in microelectronics. This development has led to an increased use of workstations connected in the form of a powerful distributed computing system. Potential benefits offered by such distributed computing systems include better cost performance, enhanced fault tolerance, increased system throughput, and efficient sharing of resources. Distributed program reliability is an important measure that should be examined for designing a high fault-tolerance distributed computing system. This reliability varies according to (1) the topology of the distributed computing system, (2) the reliability of the communication edges, (3) the data files and programs distribution among processing elements, and (4) the data files required to execute a program. This article is concerned with the analysis of distributed program reliability on star distributed computing systems.
5909240
The Computational Complexity of the Reliability Problem on Distributed Systems
Abstract The reliability of a distributed program in a distributed computing system is the probability that a program which runs on multiple processing elements and needs to communicate with other processing elements for remote data files will be executed successfully. This reliability varies according to 1. (1) the topology of the distributed computing system 2. (2) the reliability of the communication links 3. (3) the data files and program distribution among processing elements and 4. (4) the data files required to execute a program. This paper shows that solving this reliability problem is NP-hard even when the distributed computing system is restricted to a series-parallel, a 2-tree, a tree, or a star structure.
50312
The distributed program reliability analysis on ring-type topologies
Abstract Distributed computing system (DCS) has become very popular for its high fault-tolerance, potential for parallel processing, and better reliability performance. One of the important issues in the design of the DCS is the reliability performance. Distributed program reliability (DPR) is addressed to obtain this reliability measure. In this paper, we propose a polynomial-time algorithm for computing the DPR of ring topology and show that solving the DPR problem on a ring of trees topology is NP-hard. Scope and purpose The widespread use of distributed computing system is due to the price–performance revolution in microelectronics, the development of cost-effective and efficient communication subsets, the development of resource sharing software, and the increased user demands for communication, economical sharing of resources, and productivity. This article is concerned with the analysis of distributed program reliability on a ring-distributed computing system. The distributed program reliability is a useful measure for reliability evaluation of distributed computing system. The distributed program reliability analyses also give a good index for designing a high-reliability-performance-distributed computing system.
30294156
Cycle embedding in faulty wrapped butterfly graphs
In this paper, we study the maximal length of cycle embedding in a faulty wrapped butterfly graph BFn with at most two faults in vertices and/or edges. When there is one vertex fault and one edge fault, we prove that the maximum cycle length is n2n − 2 if n is even and n2n − 1 if n is odd. When there are two faulty vertices, the maximum cycle length is n2n − 2 for odd n. All these results are optimal because the wrapped butterfly graph is bipartite if and only if n is even. © 2003 Wiley Periodicals, Inc.
17862666
Virtual Interaction for Effective E-Learning
This research investigates whether information technologies, such as automated question answering (QA), can add interactivity into a multimedia-based e-learning system, as well as how this type of virtual interaction affects the effectiveness of e-learning. Based on a review of multiple learning theories and technologies, an exploratory model for studying the effectiveness of interactive e-learning, Learning with Virtual Mentors (LVM), is proposed and a prototype system is developed to implement the LVM model. A series of studies, including a controlled experiment and surveys, have been conducted to explore the relationships among the core constructs of the LVM model: learning phases, system interactivity, learning activity, and learning outcomes. Findings indicate that virtual interaction positively impacts student behaviors by encouraging students to interact more and increasing student satisfaction with the learning process; however, the correlation between virtual interaction and actual learning performance is limited. Consequently, the LVM model needs to be further explored and developed.
16043357
Six-degree-of-freedom haptic display using localized contact computations
We present a six-degree-of-freedom haptic rendering algorithm using localized contact computations. It takes advantage of high motion coherence due to fast force update and spatial locality near the contact regions. We first decompose the surface of each polyhedron into convex pieces and construct bounding volume hierarchies for fast proximity queries. Once the objects are intersecting, the penetration depth (PD) is estimated in the contact neighborhood between each pair of decomposed convex pieces, using a new incremental method based on local optimization. Given the computed PD values, multiple contacts near a local region are clustered together to further speed up contact force determination. We have implemented these algorithms and applied them to complex contact scenarios consisting of multiple contacts.
30756082
Sensation preserving simplification for haptic rendering
986758
The Interaction of Research Methods for System Evaluation and Theory Testing: A New Vision of the Benefits of Multi-Methodological Information Systems Research
A number of multi-methodological Information Systems research frameworks have been proposed to guide research in the IS field. In this paper, we describe a three-year program of research evaluating a computerbased training system for deception detection (Agent99 Trainer) using one such multi-methodological IS framework. The process and results of this research program clearly demonstrate the benefits of combining and triangulating multiple research methods. Moreover, through the experiences in the Agent99 Trainer study, we discover two different types of interactions between the research methods that were applied in this study. One of the interactions is between the results from different methods, while the other is between the results and the methods themselves. Hence, we propose an extended interpretation of multi-methodological IS research frameworks to incorporate these two types of interactions between research methods. We argue that this extended interpretation will provide a more specific explanation for why the triangulation among multiple research methods can provide benefits to IS research.