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Data Flow (data + flow)

Distribution by Scientific Domains
Engineering40%

Selected Abstracts

Structural testing criteria for message-passing parallel programs

CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 16 2008
S. R. S. Souza
Abstract Parallel programs present some features such as concurrency, communication and synchronization that make the test a challenging activity. Because of these characteristics, the direct application of traditional testing is not always possible and adequate testing criteria and tools are necessary. In this paper we investigate the challenges of validating message-passing parallel programs and present a set of specific testing criteria. We introduce a family of structural testing criteria based on a test model. The model captures control and data flow of the message-passing programs, by considering their sequential and parallel aspects. The criteria provide a coverage measure that can be used for evaluating the progress of the testing activity and also provide guidelines for the generation of test data. We also describe a tool, called ValiPar, which supports the application of the proposed testing criteria. Currently, ValiPar is configured for parallel virtual machine (PVM) and message-passing interface (MPI). Results of the application of the proposed criteria to MPI programs are also presented and analyzed. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Competitive flow control in general multi-node multi-link communication networks

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 2 2008
Ismet Sahin
Abstract In this paper, we consider the flow control in a general multi-node multi-link communication network with competing users. Each user has a source node, a destination node, and an existing route for its data flow over any set of links in the network from its source to its destination node. The flow rate for each user is a control variable that is determined by optimizing a user-specific utility function which combines maximizing the flow rate and minimizing the network congestion for that user. A preference parameter in the utility function allows each user to adjust the trade-off between these two objectives. Since all users share the same network resources and are only interested in optimizing their own utility functions, the Nash equilibrium of game theory represents a reasonable solution concept for this multi-user general network. The existence and uniqueness of such an equilibrium is therefore very important for the network to admit an enforceable flow configuration. In this paper, we derive an expression for the Nash equilibrium and prove its uniqueness. We illustrate the results with an example and discuss some properties and observations related to the network performance when in the Nash equilibrium. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Content-aware full search scheme for motion estimation

INTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY, Issue 6 2004
Shih-Yu Huang
Abstract Taking into consideration computational complexity and design regularity, this article proposes a content-aware full search (CAFS) block matching scheme for motion estimation. Full search (FS) is widely employed in hardware design of block matching because of its regular data flow. But the huge computational complexity of FS makes it infeasible especially in low-power environments. To reduce the required computational complexity, CAFS using a content-aware computation allocation mechanism dynamically distributes computation to blocks with distinct motion content based on center-biased distribution characteristics of motion vectors. Because all operations of CAFS can be performed by a series of ±2 FSs, the hardware of CAFS can be easily extended by the design of FS. Experimental results indicates that CAFS can achieve about 0.5,1.4 dB quality improvement over original FS in football and table tennis sequences under the same computation. © 2005 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 14, 246,252, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.20028 [source]

Underwater SLAM in man-made structured environments

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 11-12 2008
David Ribas
This paper describes a navigation system for autonomous underwater vehicles (AUVs) in partially structured environments, such as dams, harbors, marinas, and marine platforms. A mechanically scanned imaging sonar is used to obtain information about the location of vertical planar structures present in such environments. A robust voting algorithm has been developed to extract line features, together with their uncertainty, from the continuous sonar data flow. The obtained information is incorporated into a feature-based simultaneous localization and mapping (SLAM) algorithm running an extended Kalman filter. Simultaneously, the AUV's position estimate is provided to the feature extraction algorithm to correct the distortions that the vehicle motion produces in the acoustic images. Moreover, a procedure to build and maintain a sequence of local maps and to posteriorly recover the full global map has been adapted for the application presented. Experiments carried out in a marina located in the Costa Brava (Spain) with the Ictineu AUV show the viability of the proposed approach. © 2008 Wiley Periodicals, Inc. [source]

Scientific infrastructure design: Information environments and knowledge provinces

PROCEEDINGS OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE & TECHNOLOGY (ELECTRONIC), Issue 1 2007
Karen S. Baker
Conceptual models and design processes shape the practice of information infrastructure building in the sciences. We consider two distinct perspectives: (i) a cyber view of disintermediation where information technology enables data flow from the ,field' and on to the digital doorstep of the general end-user, and (ii) an intermediated view with bidirectional communications where local participants act as mediators within an information environment. Drawing from the literatures of information systems and science studies, we argue that differences in conceptual models have critical implications for users and their working environments. While the cyber view is receiving a lot of attention in current scientific efforts, highlighting the multiplicity of knowledge provinces with their respective worldviews opens up understandings of sociotechnical design processes and of knowledge work. The concept of a range of knowledge provinces enables description of dynamic configurations with shifting boundaries and supports planning for a diversity of arrangements across the digital landscape. [source]