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Computer Engineering Commons™

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2006

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Articles 331 - 360 of 508

Full-Text Articles in Computer Engineering

Design Of A Diversified Network Substrate, Jonathan Turner Jan 2006

Design Of A Diversified Network Substrate, Jonathan Turner

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A diversified network substrate enables multiple end-to-end metanetworks to co-exist within a shared physical infrastructure. Metanetworks are implemented by metarouters, hosted by substrate routers, and metarouters are connected by metalinks. The substrate allocates resources (both link bandwidth and processing resources) to metarouters based on advance reservations received from metanetwork planning systems. It also enables dynamic creation of access metalinks, connecting end systems to metarouters, and supports mobility of end systems under the control of their metanetworks. This report defines a model for a diversified internet and presents a detailed design of the substrate that enables metanetworks to co-exist. The design …

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Discovering Functional Modules By Clustering Gene Co-Expression Networks, Jianhua Ruan, Weixiong Zhang Jan 2006

Discovering Functional Modules By Clustering Gene Co-Expression Networks, Jianhua Ruan, Weixiong Zhang

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Identification of groups of functionally related genes from high throughput gene expression data is an important step towards elucidating gene functions at a global scale. Most existing approaches treat gene expression data as points in a metric space, and apply conventional clustering algorithms to identify sets of genes that are close to each other in the metric space. However, they usually ignore the topology of the underlying biological networks. In this paper, we propose a network-based clustering method that is biologically more realistic. Given a gene expression data set, we apply a rank-based transformation to obtain a sparse co-expression network, …

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Fast Packet Classification Using Bloom Filters, Sarang Dharmapurikar, Haoyu Song, Jonathan Turner, John Lockwood Jan 2006

Fast Packet Classification Using Bloom Filters, Sarang Dharmapurikar, Haoyu Song, Jonathan Turner, John Lockwood

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While the problem of general packet classification has received a great deal of attention from researchers over the last ten years, there is still no really satisfactory solution. Ternary Content Addressable Memory (TCAM), although widely used in practice, is both expensive and consumes a lot of power. Algorithmic solutions, which rely on commodity memory chips, are relatively inexpensive and power-efficient, but have not been able to match the generality and performance of TCAMs. In this paper we propose a new approach to packet classification, which combines architectural and algorithmic techniques. Our starting point is the well-known crossproducting algorithm, which is …

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Acceleration Of Gapped Alignment In Blastp Using The Mercury System, Brandon B. Harris Jan 2006

Acceleration Of Gapped Alignment In Blastp Using The Mercury System, Brandon B. Harris

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Protein databases have grown exponentially over the last decade. This exponential growth has made extracting valuable information from these databases increasingly time consuming. This project presents a new method of accelerating a commonly used program for performing similarity searching on protein databases, BLASTP. This project describes the design and implementation of Mercury BLASTP, a customized hardware accelerated variant of BLASTP. This project focuses on the gapped alignment stage of Mercury BLASTP and provides design details and implementation results.

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A Unified Architecture For Flexible Radio Power Management In Wireless Sensor Networks, Kevin Klues, Guoliang Xing, Chenyang Lu Jan 2006

A Unified Architecture For Flexible Radio Power Management In Wireless Sensor Networks, Kevin Klues, Guoliang Xing, Chenyang Lu

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A challenge for many wireless sensor networks is to remain operational for long periods of time on a very limited power supply. While many power management protocols have been proposed, a solution does not yet exist that allows them to be seamlessly integrated into the existing systems. In this paper we study the architectural support required to resolve this issue. We propose a framework that separates sleep scheduling from the basic MAC layer functionality and provide a set of unified interfaces between them. This framework enables different sleep scheduling policies to be easily implemented on top of multiple MAC layers. …

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Flexible Maximum Urgency First Scheduling For Distributed Real-Time Systems, Yingming Chen, Chenyang Lu Jan 2006

Flexible Maximum Urgency First Scheduling For Distributed Real-Time Systems, Yingming Chen, Chenyang Lu

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No abstract provided.

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A Thesis On Sketch-Based Techniques For Mesh Deformation And Editing, Raquel Bujans Jan 2006

A Thesis On Sketch-Based Techniques For Mesh Deformation And Editing, Raquel Bujans

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The goal of this research is to develop new and more intuitive ways for editing a mesh from a static camera angle. I present two ways to edit a mesh via a simple sketching system. The first method is a gray-scale editor which allows the user to specify a fall off function for the region being deformed. The second method is a profile editor in which the user can re-sketch a mesh’s profile. Lastly, the types of edits possible will be discussed and our results will be presented.

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Design And Evaluation Of Packet Classification Systems, Doctoral Dissertation, December 2006, Haoyu Song Jan 2006

Design And Evaluation Of Packet Classification Systems, Doctoral Dissertation, December 2006, Haoyu Song

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Although many algorithms and architectures have been proposed, the design of efficient packet classification systems remains a challenging problem. The diversity of filter specifications, the scale of filter sets, and the throughput requirements of high speed networks all contribute to the difficulty. We need to review the algorithms from a high-level point-of-view in order to advance the study. This level of understanding can lead to significant performance improvements. In this dissertation, we evaluate several existing algorithms and present several new algorithms as well. The previous evaluation results for existing algorithms are not convincing because they have not been done in …

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Hail: An Algorithm For The Hardware Accelerated Identification Of Languages, Master's Thesis, May 2006, Charles M. Kastner Jan 2006

Hail: An Algorithm For The Hardware Accelerated Identification Of Languages, Master's Thesis, May 2006, Charles M. Kastner

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This thesis examines in detail the Hardware-Accelerated Identification of Languages (HAIL) project. The goal of HAIL is to provide an accurate means to identify the language and encoding used in streaming content, such as documents passed over a high-speed network. HAIL has been implemented on the Field-programmable Port eXtender (FPX), an open hardware platform developed at Washington University in St. Louis. HAIL can accurately identify the primary languages and encodings used in text at rates much higher than what can be achieved by software algorithms running on microprocessors.

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A Query-Centric Approach To Supporting The Development Of Context-Aware Applications For Mobile Ad Hoc Networks, Doctoral Dissertation, August 2006, Jamie Payton Jan 2006

A Query-Centric Approach To Supporting The Development Of Context-Aware Applications For Mobile Ad Hoc Networks, Doctoral Dissertation, August 2006, Jamie Payton

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The wide-spread use of mobile computing devices has led to an increased demand for applications that operate dependably in opportunistically formed networks. A promising approach to supporting software development for such dynamic settings is to rely on the context-aware computing paradigm, in which an application views the state of the surrounding ad hoc network as a valuable source of contextual information that can be used to adapt its behavior. Collecting context information distributed across a constantly changing network remains a significant technical challenge. This dissertation presents a query-centered approach to simplifying context interactions in mobile ad hoc networks. Using such …

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Unified Power Management In Wireless Sensor Networks, Doctoral Dissertation, August 2006, Guoliang Xing Jan 2006

Unified Power Management In Wireless Sensor Networks, Doctoral Dissertation, August 2006, Guoliang Xing

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Radio power management is of paramount concern in wireless sensor networks (WSNs) that must achieve long lifetimes on scarce amount of energy. Previous work has treated communication and sensing separately, which is insufficient for a common class of sensor networks that must satisfy both sensing and communication requirements. Furthermore, previous approaches focused on reducing energy consumption in individual radio states resulting in suboptimal solutions. Finally, existing power management protocols often assume simplistic models that cannot accurately reflect the sensing and communication properties of real-world WSNs. We develop a unified power management approach to address these issues. We first analyze the …

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Competent Program Evolution, Doctoral Dissertation, December 2006, Moshe Looks Jan 2006

Competent Program Evolution, Doctoral Dissertation, December 2006, Moshe Looks

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Heuristic optimization methods are adaptive when they sample problem solutions based on knowledge of the search space gathered from past sampling. Recently, competent evolutionary optimization methods have been developed that adapt via probabilistic modeling of the search space. However, their effectiveness requires the existence of a compact problem decomposition in terms of prespecified solution parameters. How can we use these techniques to effectively and reliably solve program learning problems, given that program spaces will rarely have compact decompositions? One method is to manually build a problem-specific representation that is more tractable than the general space. But can this process be …

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Limit Crossing For Decision Problems, Sharlee Climer, Weixiong Zhang Jan 2006

Limit Crossing For Decision Problems, Sharlee Climer, Weixiong Zhang

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Limit crossing is a methodology in which modified versions of a problem are solved and compared, yielding useful information about the original problem. Pruning rules that are used to exclude portions of search trees are excellent examples of the limit-crossing technique. In our previous work, we examined limit crossing for optimization problems. In this paper, we extend this methodology to decision problems. We demonstrate the use of limit crossing in our design of a tool for identifying K-SAT backbones. This tool is guaranteed to identify all of the backbone variables by solving at most n+1 formulae, where n is the …

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A Proposed Architecture For The Geni Backbone Platform, Jonathan Turner Jan 2006

A Proposed Architecture For The Geni Backbone Platform, Jonathan Turner

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The GENI Project (Global Environment for Network Innovation) is a major NSF-sponsored initiative that seeks to create a national research facility to enable experimental deployment of innovative new network architectures on a sufficient scale to enable realistic evaluation. One key component of the GENI system will be the GENI Backbone Platform (GBP) that provides the resources needed to allow multiple experimental networks to co-exist within the shared GENI infrastructure. This report reviews the objectives for the GBP, reviews the key issues that affect its design and develops a detailed reference architecture in order to provide a concrete example for how …

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The Real Effect Of Warm-Cool Colors, Reynold J. Bailey, Cindy M, Grimm, Chris Davoli Jan 2006

The Real Effect Of Warm-Cool Colors, Reynold J. Bailey, Cindy M, Grimm, Chris Davoli

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The phenomenon of warmer colors appearing nearer in depth to viewers than cooler colors has been studied extensively by psychologists and other vision researchers. The vast majority of these studies have asked human observers to view physically equidistant, colored stimuli and compare them for relative depth. However, in most cases, the stimuli presented were rather simple: straight colored lines, uniform color patches, point light sources, or symmetrical objects with uniform shading. Additionally, the colors used were typically highly saturated. Although such stimuli are useful in isolating and studying depth cues in certain contexts, they leave open the question of whether …

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Tuple Space Coordination Across Space & Time, Gruia-Catalin Roman, Radu Handorean, Chenyang Lu Jan 2006

Tuple Space Coordination Across Space & Time, Gruia-Catalin Roman, Radu Handorean, Chenyang Lu

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CAST is a coordination model designed to support interactions among agents executing on hosts that make up a mobile ad hoc network (MANET). From an application programmer’s point of view, CAST makes it possible for operations to be executed at arbitrary locations in space, at prescribed times which may be in the future, and on remote hosts even when no end-to-end connected route exists between the initiator and target(s) of the operation. To accomplish this, CAST assumes that each host moves in space in accordance with a motion profile which is accurate but which at any given time extends into …

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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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