Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

2006

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 8461 - 8490 of 11490

Full-Text Articles in Entire DC Network

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

All Computer Science and Engineering Research

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 …

Go to article

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

All Computer Science and Engineering Research

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, …

Go to article

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

All Computer Science and Engineering Research

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 …

Go to article

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

All Computer Science and Engineering Research

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 …

Go to article

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

All Computer Science and Engineering Research

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 …

Go to article

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, …

Go to article

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

All Computer Science and Engineering Research

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 …

Go to article

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

All Computer Science and Engineering Research

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 …

Go to article

Smooth Surface Reconstruction Using Charts For Medical Data, Cindy Grimm, Tao Ju Jan 2006

Smooth Surface Reconstruction Using Charts For Medical Data, Cindy Grimm, Tao Ju

All Computer Science and Engineering Research

We present a surface reconstruction technique that constructs a smooth analytic surface from scattered data. The technique is robust to noise and both poorly and non-uniformly sampled data, making it well-suited for use in medical applications. In addition, the surface can be parameterized in multiple ways, making it possible to represent additional data, such as electromagnetic potential, in a different (but related) coordinate system to the geometric one. The parameterization technique also supports consistent parameterizations of multiple data sets.

Go to article

Design Issues Of Reserved Delivery Subnetworks, Doctoral Dissertation, May 2006, Ruibiao Qiu Jan 2006

Design Issues Of Reserved Delivery Subnetworks, Doctoral Dissertation, May 2006, Ruibiao Qiu

All Computer Science and Engineering Research

The lack of per-flow bandwidth reservation in today's Internet limits the quality of service that an information service provider can provide. This dissertation introduces the reserved delivery subnetwork (RDS), a mechanism that provides consistent quality of service by implementing aggregate bandwidth reservation. A number of design and deployment issues of RDSs are studied. First, the configuration problem of a single-server RDS is formulated as a minimum concave cost network flow problem, which properly reflects the economy of bandwidth aggregation, but is also an NP-hard problem. To make the RDS configuration problem tractable, an efficient approximation heuristic, largest demands first (LDF), …

Go to article

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 …

Go to article

Mixed-Integer Linear Programming Solution To Multi-Robot Task Allocation Problem, Nuzhet Atay, Burchan Bayazit Jan 2006

Mixed-Integer Linear Programming Solution To Multi-Robot Task Allocation Problem, Nuzhet Atay, Burchan Bayazit

All Computer Science and Engineering Research

Multi-robot systems require efficient and accurate planning in order to perform mission-critical tasks. This paper introduces a mixed-integer linear programming solution to coordinate multiple heterogenenous robots for detecting and controlling multiple regions of interest in an unknown environment. The objective function contains four basic requirements of a multi-robot system serving this purpose: control regions of interest, provide communication between robots, control maximum area and detect regions of interest. Our solution defines optimum locations of robots in order to maximize the objective function while efficiently satisfying some constraints such as avoiding obstacles and staying within the speed capabilities of the robots. …

Go to article

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

All Computer Science and Engineering Research

No abstract provided.

Go to article

A Theory Of Load Adjustments And Its Implications For Congestion Control, Sergey Gorinsky, Manfred Georg, Maxim Podlesny, Christoph Jechlitschek Jan 2006

A Theory Of Load Adjustments And Its Implications For Congestion Control, Sergey Gorinsky, Manfred Georg, Maxim Podlesny, Christoph Jechlitschek

All Computer Science and Engineering Research

Multiplicative Increase (MI), Additive Increase (AI), and Multiplicative Decrease (MD) are linear adjustments used extensively in networking. However, their properties are not fully understood. We analyze responsiveness (time for the total load to reach the target load), smoothness (maximal size of the total load oscillations after reaching the target load), fairing speed (speed of convergence to equal individual loads) and scalabilities of MAIMD algorithms, which generalize AIMD algorithms via optional inclusion of MI. We prove that an MAIMD can provide faster asymptotic fairing than a less smooth AIMD. Furthermore, we discover that loads under a specific MAIMD converge from any …

Go to article

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

All Computer Science and Engineering Research

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 …

Go to article

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

All Computer Science and Engineering Research

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 …

Go to article

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 …

Go to article

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

All Computer Science and Engineering Research

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.

Go to article

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

All Computer Science and Engineering Research

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. …

Go to article

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

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

All Computer Science and Engineering Research

In many wireless sensor networks, energy is an extremely limited resource. While many different power management strategies have been proposed to help reduce the amount of energy wasted, application developers still face two fundamental challenges when developing systems with stringent power constraints. First, existing power management strategies are usually tightly coupled with network protocols and other system functionality. This monolithic approach has led to standalone solutions that cannot easily be reused or extended to other applications or platforms. Second, different power management strategies make different and sometimes even conflicting assumptions about the rest of the system with which they need …

Go to article

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 …

Go to article

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

All Computer Science and Engineering Research

No abstract provided.

Go to article

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

All Computer Science and Engineering Research

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 …

Go to article

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

All Computer Science and Engineering Research

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 …

Go to article

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

All Computer Science and Engineering Research

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 …

Go to article

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, …

Go to article

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

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

All Computer Science and Engineering Research

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 …

Go to article

Design Of Routers For Diversified Networks, Jonathan Turner Jan 2006

Design Of Routers For Diversified Networks, Jonathan Turner

All Computer Science and Engineering Research

No abstract provided.

Go to article

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 …

Go to article

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

All Computer Science and Engineering Research

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.

Go to article

First Prev Next Last