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Articles 22801 - 22830 of 25652

Full-Text Articles in Engineering

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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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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A Comprehensive Analysis Of The Effect Of Microarray Data, Monika Ray, Johannes Freudenberg, Weixiong Zhang Jan 2006

A Comprehensive Analysis Of The Effect Of Microarray Data, Monika Ray, Johannes Freudenberg, Weixiong Zhang

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Background: Microarray data preprocessing, such as differentially expressed (DE) genes selection, is performed prior to higher level statistical analysis in order to account for technical variability. Preprocessing for the Affymetrix GeneChip includes background correction, normalisation and summarisation. Numerous preprocessing methods have been proposed with little consensus as to which is the most suitable. Furthermore, due to poor concordance among results from cross-platform analyses, protocols are being developed to enable cross-platform reproducibility. However, the effect of data analysis on a single platform is still unknown. The objective of our study is two-fold: first to determine whether there is consistency in the …

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Three Dimensional Panoramic Fast Flourescence Imaging Of Cardiac Arryhtymias In The Rabbit Heart, Fujian Qu, Vladimir P. Nikolski, Cindy Grimm, Igor R. Efimov Jan 2006

Three Dimensional Panoramic Fast Flourescence Imaging Of Cardiac Arryhtymias In The Rabbit Heart, Fujian Qu, Vladimir P. Nikolski, Cindy Grimm, Igor R. Efimov

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Cardiac high spatio-temporal optical mapping provides a unique opportunity to investigate the dynamics of propagating waves of excitation during ventricular arrhythmia and defibrillation. However, studies using single camera imaging systems are hampered by the inability to monitor electrical activity from the entire surface of the heart. We have developed a three dimensional panoramic imaging system which allows high-resolution and high-dynamic-range optical mapping from the entire surface of the heart. Rabbit hearts (n=4) were Langendorff perfused and imaged by the system during sinus rhythm, epicardial pacing, and arrhythmias. The reconstructed 3D electrical activity provides us with a powerful tool to investigate …

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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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A View-Based Deformation Tool-Kit, Master's Thesis, August 2006, Nisha Sudarsanam Jan 2006

A View-Based Deformation Tool-Kit, Master's Thesis, August 2006, Nisha Sudarsanam

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Camera manipulation is a hard problem since a graphics camera is defined by specifying 11 independent parameters. Manipulating such a high-dimensional space to accomplish specific tasks is difficult and requires a certain amount of expertise. We present an intuitive interface that allows novice users to perform camera operations in terms of the change they want see in the image. In addition to developing a natural means for camera interaction, our system also includes a novel interface for viewing and organizing previously saved views. When exploring complex 3D data-sets a single view is not sufficient. Instead, a composite view built from …

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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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Design And Analysis Of An Accelerated Seed Generation Stage For Blastp On The Mercury System - Master's Thesis, August 2006, Arpith Jacob Jan 2006

Design And Analysis Of An Accelerated Seed Generation Stage For Blastp On The Mercury System - Master's Thesis, August 2006, Arpith Jacob

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NCBI BLASTP is a popular sequence analysis tool used to study the evolutionary relationship between two protein sequences. Protein databases continue to grow exponentially as entire genomes of organisms are sequenced, making sequence analysis a computationally demanding task. For example, a search of the E. coli. k12 proteome against the GenBank Non-Redundant database takes 36 hours on a standard workstation. In this thesis, we look to address the problem by accelerating protein searching using Field Programmable Gate Arrays. We focus our attention on the BLASTP heuristic, building on work done earlier to accelerate DNA searching on the Mercury platform. We …

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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

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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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Preserving Performance Of Byzantine Fault Tolerant Replica Groups In The Presence Of Malicious Clients, Sajeeva L. Pallemulle, Haraldur D. Thorvaldsson, Kenneth J. Goldman Jan 2006

Preserving Performance Of Byzantine Fault Tolerant Replica Groups In The Presence Of Malicious Clients, Sajeeva L. Pallemulle, Haraldur D. Thorvaldsson, Kenneth J. Goldman

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The Castro and Liskov Byzantine Fault Tolerance protocol for replicated state machines (CLBFT) provides a practical means of tolerating arbitrary replica failures in replicated passive data servers. For better performance, CLBFT uses Message Authentication Codes (MAC) instead of public Key cryptography to authenticate messages and preserves replica consistency even in the presence of malicious clients. However, CLBFT is susceptible to potential attacks by malicious clients using corrupted MACs to force replica groups into expensive configuration changes repeatedly. While not affecting correctness, this vulnerability can seriously impair the performance of the replica group. We propose modifications to CLBFT that address this …

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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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Manifold Learning For Natural Image Sets, Doctoral Dissertation August 2006, Richard Souvenir Jan 2006

Manifold Learning For Natural Image Sets, Doctoral Dissertation August 2006, Richard Souvenir

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The field of manifold learning provides powerful tools for parameterizing high-dimensional data points with a small number of parameters when this data lies on or near some manifold. Images can be thought of as points in some high-dimensional image space where each coordinate represents the intensity value of a single pixel. These manifold learning techniques have been successfully applied to simple image sets, such as handwriting data and a statue in a tightly controlled environment. However, they fail in the case of natural image sets, even those that only vary due to a single degree of freedom, such as a …

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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

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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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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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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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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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Use Of Gene Expression Profiling And Machine Learning To Understand And Predict Primary Graft Dysfunction, Monika Ray, Sekhar Dharmarajan, Johannes Freudenberg, Weixiong Zhang, Alexander G. Patterson Jan 2006

Use Of Gene Expression Profiling And Machine Learning To Understand And Predict Primary Graft Dysfunction, Monika Ray, Sekhar Dharmarajan, Johannes Freudenberg, Weixiong Zhang, Alexander G. Patterson

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No abstract provided.

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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

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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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Extending Byzantine Fault Tolerance To Replicated Clients, Ian Wehrman, Sajeeva L. Pallemulle, Kenneth J. Goldman Jan 2006

Extending Byzantine Fault Tolerance To Replicated Clients, Ian Wehrman, Sajeeva L. Pallemulle, Kenneth J. Goldman

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Byzantine agreement protocols for replicated deterministic state machines guarantee that externally requested operations continue to execute correctly even if a bounded number of replicas fail in arbitrary ways. The state machines are passive, with clients responsible for any active ongoing application behavior. However, the clients are unreplicated and outside the fault-tolerance boundary. Consequently, agreement protocols for replicated state machines do not guarantee continued correct execution of long-running client applications. Building on the Castro and Liskov Byzantine Fault Tolerance protocol for unreplicated clients (CLBFT), we present a practical algorithm for Byzantine fault-tolerant execution of long-running distributed applications in which replicated deterministic …

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Supporting Collaborative Behavior In Manets Using Workflows, Rohan Sen, Gregory Hackmann, Mart Haitjema, Gruia-Catalin Roman, Gill Jan 2006

Supporting Collaborative Behavior In Manets Using Workflows, Rohan Sen, Gregory Hackmann, Mart Haitjema, Gruia-Catalin Roman, Gill

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Groupware activities provide a powerful representation for many collaborative tasks. Today, the technologies that support typical groupware applications often assume a stable wired network infrastructure. The potential for collaboration in scenarios that lack this fixed infrastructure remains largely untapped. Such scenarios include activities on construction sites, wilderness exploration, disaster recovery, and rapid intervention teams. Communication in these scenarios can be supported using wireless ad hoc networks, an emerging technology whose full potential is yet to be understood and realized. In this paper, we consider the fundamental technical issues that need to be addressed in order to introduce groupware concepts into …

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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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Automatic Application-Specific Customization Of Softcore Processor Microarchitecture, Masters Thesis, May 2006, Shobana Padmanabhan Jan 2006

Automatic Application-Specific Customization Of Softcore Processor Microarchitecture, Masters Thesis, May 2006, Shobana Padmanabhan

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Applications for constrained embedded systems are subject to strict runtime and resource utilization bounds. With soft core processors, application developers can customize the processor for their application, constrained by available hardware resources but aimed at high application performance. The more reconfigurable the processor is, the more options the application developers will have for customization and hence increased potential for improving application performance. However, such customization entails developing in-depth familiarity with all the parameters, in order to configure them effectively. This is typically infeasible, given the tight time-to-market pressure on the developers. Alternatively, developers could explore all possible configurations, but being …

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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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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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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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Acceleration Of Profile-Hmm Search For Protein Sequences In Reconfigurable Hardware - Master's Thesis, May 2006 , Rahul Pratap Maddimsetty Jan 2006

Acceleration Of Profile-Hmm Search For Protein Sequences In Reconfigurable Hardware - Master's Thesis, May 2006 , Rahul Pratap Maddimsetty

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Profile Hidden Markov models are highly expressive representations of functional units, or motifs, conserved across protein sequences. Profile-HMM search is a powerful computational technique that is used to annotate new sequences by identifying occurrences of known motifs in them. With the exponential growth of protein databases, there is an increasing demand for acceleration of such techniques. We describe an accelerator for the Viterbi algorithm using a two-stage pipelined design in which the first stage is implemented in parallel reconfigurable hardware for greater speedup. To this end, we identify algorithmic modifications that expose a high level of parallelism and characterize their …

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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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The Meta-Theory Of Q_0 In The Calculus Of Inductive Constructions, Master's Thesis, May 2006, Li-Yang Tan Jan 2006

The Meta-Theory Of Q_0 In The Calculus Of Inductive Constructions, Master's Thesis, May 2006, Li-Yang Tan

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The notion of a proof is central to all of mathematics. In the language of formal logic, a proof is a finite sequence of inferences from a set of axioms, and any statement one yields from such a finitistic procedure is called a theorem. For better or for worse, this is far from the form a traditional mathematical proof takes. Mathematicians write proofs that omit routine logical steps, and details deemed tangential to the central result are often elided. These proofs are fuzzy and human-centric, and a great amount of context is assumed on the part of the reader. While …

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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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Dynamic Conflict-Free Query Scheduling For Wireless Sensor Networks, Octav Chipara, Chenyang Lu, John Stankovic Jan 2006

Dynamic Conflict-Free Query Scheduling For Wireless Sensor Networks, Octav Chipara, Chenyang Lu, John Stankovic

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With the emergence of high data rate sensor network applications, there is an increasing demand for high-performance query services in such networks. To meet this challenge, we present Dynamic Conflict-free Query Scheduling (DCQS), a novel scheduling technique for queries in wireless sensor networks. In contrast to earlier TDMA protocols designed for general-purpose networks and workloads, DCQS is specifically designed for query services supporting in-network data aggregation. DCQS has several important features. First, it optimizes the query performance and energy efficiency by exploiting the temporal properties and precedence constraints introduced by data aggregation. Second, it can efficiently adapt to dynamic workloads …

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