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Articles 22771 - 22800 of 25630

Full-Text Articles in Computer Engineering

Fair Efficiency, Or Low Average Delay Without Starvation, Christoph Jechlitschek, Sergey Gorinksky Jan 2006

Fair Efficiency, Or Low Average Delay Without Starvation, Christoph Jechlitschek, Sergey Gorinksky

All Computer Science and Engineering Research

Elastic applications are primarily interested in minimal delay achievable for their messages under current network load. In this paper, we investigate how to transmit such messages over a bottleneck link efficiently and fairly.

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Virtualizing Network Processors, Ben Wun, Jonathan Turner, Patrick Crowley Jan 2006

Virtualizing Network Processors, Ben Wun, Jonathan Turner, Patrick Crowley

All Computer Science and Engineering Research

This paper considers the problem of virtualizing the resources of a network processor (NP) in order to allow multiple third-parties to execute their own virtual router software on a single physical router at the same time. Our broad interest is in designing such a router capable of supporting virtual networking. We discuss the issues and challenges involved in this virtualization, and then describe specific techniques for virtualizing both the control and data-plane processors on NPs. For Intel IXP NPs in particular, we present a dynamic, macro-based technique for virtualization that allows multiple virtual routers to run on multiple data plane …

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An Improved Analysis For A Greedy Remote-Clique Algorithm Using Factor-Revealing Lps, Benjamin E. Birnbaum, Kenneth J. Goldman Jan 2006

An Improved Analysis For A Greedy Remote-Clique Algorithm Using Factor-Revealing Lps, Benjamin E. Birnbaum, Kenneth J. Goldman

All Computer Science and Engineering Research

Given a complete graph with nonnegative edge weights satisfying the triangle inequality and a positive integer p, the remote-clique problem is to find a subset of p vertices having a maximum-weight induced subgraph. A simple greedy algorithm for the problem has been shown to have an approximation ratio of 4, but a tight example has not been provided. In this paper, we use the technique of factor revealing linear programs to prove that this algorithm actually achieves an approximation ratio of 2, matching the best-known ratio for the problem. The greedy algorithm's running time of O(pn) makes it the fastest …

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Agilla: A Mobile Agent Middleware For Sensor Networks, Chien-Liang Fok, Gruia-Catalin Roman, Chenyang Lu Jan 2006

Agilla: A Mobile Agent Middleware For Sensor Networks, Chien-Liang Fok, Gruia-Catalin Roman, Chenyang Lu

All Computer Science and Engineering Research

Agilla is a mobile agent middleware for sensor networks. Mobile agents are special processes that can migrate across sensors. They increase network flexibility by enabling active in-network reprogramming. Neighbor lists and tuple spaces are used for agent coordination. Agilla was originally implemented on Mica2 motes, but has been ported to other platforms. Its Mica2 implementation consumes 41.6KB of code and 3.59KB of data memory. Agents can move five hops in less than 1.1s with over 92% success. Agilla was used to develop multiple applications related to fire detection and tracking, cargo container monitoring, and robot navigation.

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Feature Detection Using Curvature Maps And The Min-Cut/Max-Flow Graph Cut Algorithm, Timothy Gatzke, Cindy Grimm Jan 2006

Feature Detection Using Curvature Maps And The Min-Cut/Max-Flow Graph Cut Algorithm, Timothy Gatzke, Cindy Grimm

All Computer Science and Engineering Research

Automatic detection of features in three-dimensional objects is a critical part of shape matching tasks such as object registration and recognition. Previous approaches to local surface matching have either focused on man-made objects, where features are generally well-defined, or required some type of user interaction to select features. Manual selection of corresponding features and subjective determination of the difference between objects are time consuming processes requiring a high level of expertise. Curvature is a useful property of a surface, but curvature calculation on a discrete mesh is often noisy and not always accurate. However, the em Curvature Map, which represents …

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Distributed Utilization Control For Real-Time Clusters With Load Balancing, Yong Fu, Hongan Wang, Chenyang Lu, Ramu S. Chandra Jan 2006

Distributed Utilization Control For Real-Time Clusters With Load Balancing, Yong Fu, Hongan Wang, Chenyang Lu, Ramu S. Chandra

All Computer Science and Engineering Research

Recent years have seen rapid growth of online services that rely on large-scale server clusters to handle high volume of requests. Such clusters must adaptively control the CPU utilizations of many processors in order to maintain desired soft real-time performance and prevent system overload in face of unpredictable workloads. This paper presents DUC-LB, a novel distributed utilization control algorithm for cluster-based soft real-time applications. Compared to earlier works on utilization control, a distinguishing feature of DUC-LB is its capability to handle system dynamics caused by load balancing, which is a common and essential component of most clusters today. Simulation results …

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Mobiwork: Mobile Workflow For Manets, Gregory Hackmann, Rohan Sen, Mart Haitjema, Gruia-Catalin Roman, Gill Jan 2006

Mobiwork: Mobile Workflow For Manets, Gregory Hackmann, Rohan Sen, Mart Haitjema, Gruia-Catalin Roman, Gill

All Computer Science and Engineering Research

The workflow model is well suited for scenarios where many entities work collaboratively towards a common goal, and is used widely today to model complex business processes. However, the fundamental workflow model is very powerful and can be applied to a wider variety of application domains. This paper represents an initial investigation into the possibility of using workflows to model collaboration in an ad hoc mobile environment. Moving to a mobile setting introduces many challenges as the mobility of the participants in a workflow imposes constraints on allocation of workflow tasks, coordination among participants, and marshaling of results. We present …

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Efficient Mapping Of Virtual Networks Onto A Shared Substrate, Jing Lu, Jonathan Turner Jan 2006

Efficient Mapping Of Virtual Networks Onto A Shared Substrate, Jing Lu, Jonathan Turner

All Computer Science and Engineering Research

Virtualization has been proposed as a vehicle for overcoming the growing problem of internet ossification [1]. This paper studies the problem of mapping diverse virtual networks onto a common physical substrate. In particular, we develop a method for mapping a virtual network onto a substrate network in a cost-efficient way, while allocating sufficient capacity to virtual network links to ensure that the virtual network can handle any traffic pattern allowed by a general set of traffic constraints. Our approach attempts to find the best topology in a family of backbone-star topologies, in which a subset of nodes constitute the backbone, …

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Adaptive Embedded Roadmaps For Sensor Networks, Gazihan Alankus, Nuzhet Atay, Chenyang Lu, Burchan Bayazit Jan 2006

Adaptive Embedded Roadmaps For Sensor Networks, Gazihan Alankus, Nuzhet Atay, Chenyang Lu, Burchan Bayazit

All Computer Science and Engineering Research

In this paper, we propose a new approach to wireless sensor network assisted navigation while avoiding moving dangers. Our approach relies on an embedded roadmap in the sensor network that always contains safe paths. The roadmap is adaptive, i.e., it adapts its topology to changing dangers. The mobile robots in the environment uses the roadmap to reach their destinations. We evaluated the performance of embedded roadmap both in simulations using realistic conditions and with real hardware. Our results show that the proposed navigation algorithm is better suited for sensor networks than traditional navigation field based algorithms. Our observations suggest that …

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Control Of Decoherence In Open Quantum Systems, Narayan Ganesan Jan 2006

Control Of Decoherence In Open Quantum Systems, Narayan Ganesan

All Computer Science and Engineering Research

No abstract provided.

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Knuth-Bendix Completion With Modern Termination Checking, Master's Thesis, August 2006, Ian Wehrman Jan 2006

Knuth-Bendix Completion With Modern Termination Checking, Master's Thesis, August 2006, Ian Wehrman

All Computer Science and Engineering Research

Knuth-Bendix completion is a technique for equational automated theorem proving based on term rewriting. This classic procedure is parametrized by an equational theory and a (well-founded) reduction order used at runtime to ensure termination of intermediate rewriting systems. Any reduction order can be used in principle, but modern completion tools typically implement only a few classes of such orders (e.g., recursive path orders and polynomial orders). Consequently, the theories for which completion can possibly succeed are limited to those compatible with an instance of an implemented class of orders. Finding and specifying a compatible order, even among a small number …

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Sliver: A Bpel Workflow Process Execution Engine For Mobile Devices, Gregory Hackmann, Mart Haitjema, Christopher Gill, Catalin-Gruia Roman Jan 2006

Sliver: A Bpel Workflow Process Execution Engine For Mobile Devices, Gregory Hackmann, Mart Haitjema, Christopher Gill, Catalin-Gruia Roman

All Computer Science and Engineering Research

The Business Process Execution Language (BPEL) has become the dominant means for expressing traditional business processes as workflows. The widespread deployment of mobile devices like PDAs and mobile phones has created a vast computational and communication resource for these workflows to exploit. However, BPEL so far has been deployed only on relatively heavyweight server platforms such as Apache Tomcat, leaving the potential created by these lower-end devices untapped. This paper presents Sliver, a BPEL workflow process execution engine that supports a wide variety of devices ranging from mobile phones to desktop PCs. We discuss the design decisions that allow Sliver …

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Reusable Models For Timing And Liveness Analysis Of Middleware For Distributed Real-Time And Embedded Systems, Venkita Subramonian, Christopher Gill, Cesar Sanchez, Henny Sipma Jan 2006

Reusable Models For Timing And Liveness Analysis Of Middleware For Distributed Real-Time And Embedded Systems, Venkita Subramonian, Christopher Gill, Cesar Sanchez, Henny Sipma

All Computer Science and Engineering Research

Distributed real-time and embedded (DRE) systems have stringent constraints on timeliness and other properties whose assurance is crucial to correct system behavior. Formal tools and techniques play a key role in verifying and validating system properties. However, many DRE systems are built using middleware frameworks that have grown increasingly complex to address the diverse requirements of a wide range of applications. How to apply formal tools and techniques effectively to these systems, given the range of middleware configuration options available, is therefore an important research problem. This paper makes three contributions to research on formal verification and validation of middleware-based …

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Multimodal Congestion Control For Low Stable-State Queuing, Maxim Podlesny, Sergey Gorinsky Jan 2006

Multimodal Congestion Control For Low Stable-State Queuing, Maxim Podlesny, Sergey Gorinsky

All Computer Science and Engineering Research

To discover an efficient fair sending rate for a flow, Transmission Control Protocol (TCP) saturates the bottleneck link and its buffer until the router discards a packet. Such TCP-caused queuing is detrimental for interactive and other delay-sensitive applications. In this paper, we present Multimodal Control Protocol (MCP) which strives to maintain low queues and avoid congestion losses at network links. The multimodal MCP engages routers and hosts in limited explicit communication. A distinguishing property of MCP is stable transmission after converging to efficient fair states. To ensure convergence to fairness, MCP incorporates an innovative mechanism that enables a flow to …

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Dynamic Resource Management In A Static Network Operating System, Kevin Klues, Vlado Handziski, David Culler, David Gay, Phillip Levis Levis, Chenyang Lu, Adam Wolisz Jan 2006

Dynamic Resource Management In A Static Network Operating System, Kevin Klues, Vlado Handziski, David Culler, David Gay, Phillip Levis Levis, Chenyang Lu, Adam Wolisz

All Computer Science and Engineering Research

We present novel approaches to managing three key resources in an event-driven sensornet OS: memory, energy, and peripherals. We describe the factors that necessitate using these new approaches rather than existing ones. A combination of static allocation and compile-time virtualization isolates resources from one another, while dynamic management provides the flexibility and sharing needed to minimize worst-case overheads. We evaluate the effectiveness and efficiency of these management policies in comparison to those of TinyOS 1.x, SOS, MOS, and Contiki. We show that by making memory, energy, and peripherals first-class abstractions, an OS can quickly, efficiently, and accurately adjust itself to …

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Link Layer Support For Unified Radio Power Management In Wireless Sensor Networks, Kevin Klues, Guoliang Xing, Chenyang Lu Jan 2006

Link Layer Support For Unified Radio Power Management In Wireless Sensor Networks, Kevin Klues, Guoliang Xing, Chenyang Lu

All Computer Science and Engineering Research

Radio power management is of paramount concern in wireless sensor networks that must achieve long lifetimes on scarce amounts of energy. While a multitude of power management protocols have been proposed in the past, the lack of system support for flexibly integrating them with a diverse set of applications and network platforms has made them difficult to use. Instead of proposing yet another power management protocol, this paper focuses on providing link layer support towards realizing a Unified Power Management Architecture (UPMA) for flexible radio power management in wireless sensor networks. In contrast to the monolithic approaches adopted by existing …

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Cian: A Language And Middleware For Collaboration In Ad Hoc Networks, Rohan Sen, Gruia-Catalin Roman, Andrew Frank Jan 2006

Cian: A Language And Middleware For Collaboration In Ad Hoc Networks, Rohan Sen, Gruia-Catalin Roman, Andrew Frank

All Computer Science and Engineering Research

Designing software that supports collaboration among multiple users in mobile ad hoc networks is challenging due to the dynamic network topology and inherent unpredictability of the environment. However, as we increasingly migrate to using mobile computing platforms, there is a pertinent need for software that can support a wide range of collaborative activities anywhere and at any time without relying on any external infrastructure. In this paper, we adopt the workflow model to represent the structure of an activity that involves multiple tasks being performed in a structured, collaborative fashion by multiple users. Using the workflow model as a base, …

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Virtualization For A Network Processor Runtime System, Brandon Heller, Jonathan Turner, John Dehart, Patrick Crowley Jan 2006

Virtualization For A Network Processor Runtime System, Brandon Heller, Jonathan Turner, John Dehart, Patrick Crowley

All Computer Science and Engineering Research

The continuing ossification of the Internet is slowing the pace of network innovation. Network diversification presents one solution to this problem, by virtualizing the network at multiple layers. Diversified networks consist of a shared physical substrate, virtual routers (metarouters), and virtual links (metalinks). Virtualizing routers enables smooth and incremental upgrades to new network services. Our current priority for a diversified router prototype is to enable reserved slices of the network for researchers to perform repeatable, high-speed network experiments. General-purpose processors have well established techniques for virtualization, but do not scale efficiently to multi-gigabit speeds. To achieve these speeds, we employ …

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Auto-Pipe And The X Language: A Toolset And Language For The Simulation, Analysis, And Synthesis Of Heterogeneous Pipelined Architectures, Master's Thesis, August 2006, Eric J. Tyson Jan 2006

Auto-Pipe And The X Language: A Toolset And Language For The Simulation, Analysis, And Synthesis Of Heterogeneous Pipelined Architectures, Master's Thesis, August 2006, Eric J. Tyson

All Computer Science and Engineering Research

Pipelining an algorithmis a popularmethod of increasing the performance of many computation-intensive applications. Often, one wants to form pipelines composed mostly of commonly used simple building blocks such as DSP components, simple math operations, encryption, or pattern matching stages. Additionally, one may desire to map these processing tasks to different computational resources based on their relative performance attributes (e.g., DSP operations on an FPGA). Auto-Pipe is composed of the X Language, a flexible interface language that aids the description of complex dataflow topologies (including pipelines); X-Com, a compiler for the X Language; X-Sim, a tool for modeling pipelined architectures based …

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Ceg 490/690-01: Technology-Based Ventures, Forouzan Golshani, S. Narayanan Jan 2006

Ceg 490/690-01: Technology-Based Ventures, Forouzan Golshani, S. Narayanan

Computer Science & Engineering Syllabi

No abstract provided.

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Cs 205-04,05,06: Computer Literacy And Office Automation, Terri Bauer Jan 2006

Cs 205-04,05,06: Computer Literacy And Office Automation, Terri Bauer

Computer Science & Engineering Syllabi

No abstract provided.

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Mimo Communications In Ad Hoc Networks, Biao Chen, Michael J. Gans Jan 2006

Mimo Communications In Ad Hoc Networks, Biao Chen, Michael J. Gans

Electrical Engineering and Computer Science - All Scholarship

We study in this paper the network spectral efficiency in terms of bits/s/Hz of a MIMO (multiple-input multiple output) ad hoc network with K simultaneous communicating transmitter-receiver pairs. Assume that each transmitter is equipped with t antennas and each receiver implements single user detection. We show that in the absence of channel state information (CSI) at the transmitters, the asymptotic network spectral efficiency is limited by r nats/s/Hz as K -> ∞ and is independent of t and the transmit power. With CSI corresponding to the desired receiver available at the transmitter, we demonstrate that the asymptotic spectral efficiency is …

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Cs 340-01: Programming Language Workshop In Java, Ronald F. Taylor Jan 2006

Cs 340-01: Programming Language Workshop In Java, Ronald F. Taylor

Computer Science & Engineering Syllabi

This course is designed as a self-study in Java. You are expected to work independently to learn the Java language and solve a set of programming problems assigned to you using latest Java SDK available at http://java.sun.com or other software as approved by the instructor. There are no exams. We officially meet only once in a quarter. However, I will be available in the posted office hours for clarifications and general discussion of the programming assignments. Do not expect support in debugging badly documented code.

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Cs 480/680-01: Comparative Programming Languages, Michael L. Raymer Jan 2006

Cs 480/680-01: Comparative Programming Languages, Michael L. Raymer

Computer Science & Engineering Syllabi

No abstract provided.

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Cs 740-01: Algorithms, Complexity And The Theory Of Computability, Thomas Sudkamp Jan 2006

Cs 740-01: Algorithms, Complexity And The Theory Of Computability, Thomas Sudkamp

Computer Science & Engineering Syllabi

No abstract provided.

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Cs 790-01: Introduction To Parallel Algorithms, Natsuhiko Futamura Jan 2006

Cs 790-01: Introduction To Parallel Algorithms, Natsuhiko Futamura

Computer Science & Engineering Syllabi

Low-cost parallel computers such as PC clusters are becoming available, and many previously unsolvable problems can be solved using such computers. However, designing algorithms that perform well on parallel computers is often challenging. The focus of this course is on learning how to design algorithms for parallel computers and how to evaluate them.

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Cs 142-01: Computer Programming Ii, Eric Maston Jan 2006

Cs 142-01: Computer Programming Ii, Eric Maston

Computer Science & Engineering Syllabi

This course provides a continuation to the general introduction of computer programming begun in CS 141. Examples from and applications to a broad range of problems are given. The concepts covered will be applied to the Java programming language. (Students must register for both lecture and one laboratory section.)

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Cs 240-01: Introduction To Computer Science I, L. Jane Lin Jan 2006

Cs 240-01: Introduction To Computer Science I, L. Jane Lin

Computer Science & Engineering Syllabi

This course is the first in the three course sequence "Introduction to Computer Science" offered by the Computer Science department at WSU. This course presents a general introduction to C++ programming language. It introduces the fundamental capabilities of C++ language as a problem solving tool. Topics include data representation, debugging and program verification.

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Cs 242-01: Introduction To Computer Science Iii, Eric Maston Jan 2006

Cs 242-01: Introduction To Computer Science Iii, Eric Maston

Computer Science & Engineering Syllabi

This is the third and final course in the Introduction to Computer Science series. This course focuses on data structures with abstract data types, such as trees, stacks, queues, and tables.

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Cs 302-01: Client Server Databases, Karen Meyer Jan 2006

Cs 302-01: Client Server Databases, Karen Meyer

Computer Science & Engineering Syllabi

No abstract provided.

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