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Articles 22291 - 22320 of 25653

Full-Text Articles in Engineering

Distributed Allocation Of Workflow Tasks In Manets, Rohan Sen, Gruia-Catalin Roman, Christopher Gill Jan 2007

Distributed Allocation Of Workflow Tasks In Manets, Rohan Sen, Gruia-Catalin Roman, Christopher Gill

All Computer Science and Engineering Research

When multiple participants work on a workflow that represents a large, collaborative activity, it is important to have a well defined process to determine the portions of the workflow that each participant is responsible for executing. In this paper, we describe a process and related algorithms required to assign tasks in a workflow, to hosts that are willing to carry out the execution of these tasks, and thereby contributing to the completion of the activity. This problem is a stylized form of the multi-processor scheduling algorithm which has been shown to be NP-Hard. Further complicating the issue is that we …

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Lower Bounds On Queuing And Loss At Highly Multiplexed Links, Maxim Podlesny, Sergey Gorinsky Jan 2007

Lower Bounds On Queuing And Loss At Highly Multiplexed Links, Maxim Podlesny, Sergey Gorinsky

All Computer Science and Engineering Research

Explicit and delay-driven congestion control protocols strive to preclude overflow of link buffers by reducing transmission upon incipient congestion. In this paper, we explore fundamental limitations of any congestion control with respect to minimum queuing and loss achievable at highly multiplexed links. We present and evaluate an idealized protocol where all flows always transmit at equal rates. The ideally smooth congestion control causes link queuing only due to asynchrony of flow arrivals, which is intrinsic to computer networks. With overprovisioned buffers, our analysis and simulations for different smooth distributions of flow interarrival times agree that minimum queuing at a fully …

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Roadmap Analysis Of Protein-Protein Interactions. Master's Thesis, August 2007, Brian C. Haynes Jan 2007

Roadmap Analysis Of Protein-Protein Interactions. Master's Thesis, August 2007, Brian C. Haynes

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The ability to effectively model the interaction between proteins is an important and open problem. In molecular biology it is well accepted that from sequence arises form and from form arises function but relating structure to function remains a challenge. The function of a given protein is defined by its interactions. Likewise a malfunction or a change in protein-protein interactions is a hallmark of many diseases. Many researchers are studying the mechanisms of protein-protein interactions and one of the overarching goals of the community is to predict whether two proteins will bind, and if so what the final conformation will …

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Perpetual: Byzantine Fault Tolerance For Federated Distributed Applications, Sajeeva L. Pallemulle, Haraldur D. Thorvaldsson, Kenneth J. Goldman Jan 2007

Perpetual: Byzantine Fault Tolerance For Federated Distributed Applications, Sajeeva L. Pallemulle, Haraldur D. Thorvaldsson, Kenneth J. Goldman

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Modern distributed applications rely upon the functionality of services from multiple providers. Mission-critical services, possibly shared by multiple applications, must be replicated to guarantee correct execution and availability in spite of arbitrary (Byzantine) faults. Furthermore, shared services must enforce strict fault isolation policies to prevent cascading failures across organizational and application boundaries. Most existing protocols for Byzantine fault-tolerant execution do not support interoperability between replicated services while others provide poor fault isolation. Moreover, existing protocols place impractical limitations on application development by disallowing long-running threads of computation, asynchronous operation invocation, and asynchronous request processing. We present Perpetual, a protocol that …

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Experimental Evaluation Of A Coarse-Grained Switch Scheduler, Charlie Wiseman, Jon Turner, Ken Wong, Brandon Heller Jan 2007

Experimental Evaluation Of A Coarse-Grained Switch Scheduler, Charlie Wiseman, Jon Turner, Ken Wong, Brandon Heller

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Modern high performance routers rely on sophisticated interconnection networks to meet ever increasing demands on capacity. Regulating the flow of packets through these interconnects is critical to providing good performance, particularly in the presence of extreme traffic patterns that result in sustained overload at output ports. Previous studies have used a combination of analysis and idealized simulations to show that coarse-grained scheduling of traffic flows can be effective in preventing congestion, while ensuring high utilization. In this paper, we study the performance of a coarse-grained scheduler in a real router with a scalable architecture similar to those found in high …

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Customizing Component Middleware For Distributed Real-Time Systems With Aperiodic And Periodic Tasks, Yuanfang Zhang, Christopher Gill, Chenyang Lu Jan 2007

Customizing Component Middleware For Distributed Real-Time Systems With Aperiodic And Periodic Tasks, Yuanfang Zhang, Christopher Gill, Chenyang Lu

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Many distributed real-time applications must handle mixed aperiodic and periodic tasks with diverse requirements. However, existing middleware lacks flexible configuration mechanisms needed to manage end-to-end timing easily for a wide range of different applications with both aperiodic and periodic tasks. The primary contribution of this work is the design, implementation and performance evaluation of the first configurable component middleware services for admission control and load balancing of aperiodic and periodic tasks in distributed real-time systems. Empirical results demonstrate the need for, and the effectiveness of, our configurable component middleware approach in supporting different applications with aperiodic and periodic tasks.

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Context-Aware Publish Subscribe In Mobile Ad Hoc Networks, Davide Frey, Gruia-Catalin Roman Jan 2007

Context-Aware Publish Subscribe In Mobile Ad Hoc Networks, Davide Frey, Gruia-Catalin Roman

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The publish-subscribe communication paradigm is enjoying increasing popularity thanks to its ability to simplify the development of complex distributed applications. However, existing solutions in the publish-subscribe domain address only part of the challenges associated with the development of applications in dynamic scenarios such as mobile ad hoc networks. Mobile applications must be able to assist users in a variety of situations, responding not only to their inputs but also to the characteristics of the environment in which they operate. In this paper, we address these challenges by extending the publish-subscribe paradigm with the ability to manage and exploit context information …

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Terahertz Data Processing For Standoff Detection Of Improvised Explosive Devices, Amit Bipin Shah Jan 2007

Terahertz Data Processing For Standoff Detection Of Improvised Explosive Devices, Amit Bipin Shah

Masters Theses

"Improvised Explosive Devices (IEDs) are homemade, non-conventional explosive devices, which are used to destruct and incapacitate individuals and property. IEDs are becoming a popular weapon of attack among terrorists and insurgents due to their easy of making and capability to cause major damage. Hence, is has become necessary to develop efficient systems for detecting and disarming these devices. The Terahertz technology which uses electromagnetic radiations between 0.3 THz to 10 THz for imaging is one of the most recently developed detection techniques and is ideally suitable for detection of IEDs and similar devices. Although a lot of work has been …

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A Simulation Environment Modeling The Use Of Wireless Sensor Networks For The Detection And Mapping Of Wildfires, Matthew Gann Jan 2007

A Simulation Environment Modeling The Use Of Wireless Sensor Networks For The Detection And Mapping Of Wildfires, Matthew Gann

Masters Theses

"Over the past 5 years, billions of dollars have been spent fighting wildfires which consume thousands of acres. Currently, satellites are the primary source of information regarding the location of large scale wildfires. The satellites in use are capable of reporting the location of the wildfire, but these reports are generated infrequently and have a low spatial resolution, where the reported location of the fire can be off by 500 meters. Timely detection (latency) and frequent report (throughput) are needed to help prevent the destruction caused by wildfires. This thesis, a system is described based on an ad-hoc wireless sensor …

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Delay-Insensitive Ternary Logic (Ditl), Ravi Sankar Parameswaran Nair Jan 2007

Delay-Insensitive Ternary Logic (Ditl), Ravi Sankar Parameswaran Nair

Masters Theses

"This thesis focuses on development of a Single Rail Ternary Voltage Delay-Insensitive paradigm called Delay-Insensitive Ternary Logic (DITL), which is based on NULL Convention Logic (NCL). Single rail asynchronous logic has potential advantages over Dual-Rail logic such as reduction of Power and Interconnect as well as Logic Area. The DITL concept is developed in steps of individual circuit components. These components are designed at the transistor level and are connected together to form a registered pipeline system. Some variations in pipeline design are also investigated"--Abstract, page iii.

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A Network Infrastructure For Real-Time Monitoring Of Campus Energy Consumption, Sandeep Kunchum Jan 2007

A Network Infrastructure For Real-Time Monitoring Of Campus Energy Consumption, Sandeep Kunchum

Masters Theses

"Pressing environmental concerns and rising energy costs have led many organizations to carefully review their energy consumption. Conservation requires that energy use be monitored accurately and continuously, to identify areas with higher energy consumption. Lighting has repeatedly been identified as such an area. A simple, yet effective method for reducing lighting energy consumption is retrofitting existing light fixtures with modern energy-efficient versions. The University of Missouri-Rolla is currently carrying out a lighting retrofit of all fixtures on campus. The pilot building for this project is McNutt Hall, as it has the single highest consumption of lighting energy. The results of …

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Security Analysis Of A Cyber-Physical System, Han Tang Jan 2007

Security Analysis Of A Cyber-Physical System, Han Tang

Masters Theses

"Cyber-Physical Systems (CPSs) are an integration of computing and physical processes. Information flow is an inherent property of CPSs and is of particular interest at their cyber-physical boundaries. This thesis focuses on discovering information flow properties and proposes a process to model the information flow in CPSs. A Cooperating FACTS Power System serves as a tangible example to illustrate modeling information flow using the proposed process. The proposed process can be used to model the information flow security, help analyze current information flow security requirements, and aid in the design of further security policies in CPS"--Abstract, page iii.

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Mlds: A Flexible Location Directory Service For Tiered Sensor Networks, Sangeeta Bhattacharya, Chien-Liang Fok, Chenyang Lu, Gruia-Catalin Roman Jan 2007

Mlds: A Flexible Location Directory Service For Tiered Sensor Networks, Sangeeta Bhattacharya, Chien-Liang Fok, Chenyang Lu, Gruia-Catalin Roman

All Computer Science and Engineering Research

Many emergent distributed sensing applications need to keep track of mobile entities across multiple sensor networks connected via an IP network. To simplify the realization of such applications, we present MLDS, a Multi-resolution Location Directory Service for tiered sensor networks. MLDS provides a rich set of spatial query services ranging from simple queries about entity location, to complex nearest neighbor queries. Furthermore, MLDS supports multiple query granularities which allow an application to achieve the desired tradeoff between query accuracy and communication cost. We implemented MLDS on Agimone, a unified middleware for sensor and IP networks. We then deployed and evaluated …

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Real-Time Query Scheduling For Wireless Sensor Networks, Octav Chipara, Chenyang Lu, Gruia-Catalin Roman Jan 2007

Real-Time Query Scheduling For Wireless Sensor Networks, Octav Chipara, Chenyang Lu, Gruia-Catalin Roman

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Recent years have seen the emergence of wireless sensor network (WSN) systems that require high data rate real-time communication. This paper proposes Real-Time Query Scheduling (RTQS), a novel approach to conflict-free transmission scheduling for real-time queries in WSNs. We show that there is an inherent trade-off between prioritization and throughput in conflict-free query scheduling. RTQS provides three new real-time scheduling algorithms. The non-preemptive query scheduling algorithm achieves high throughput while introducing priority inversions. The preemptive query scheduling algorithm eliminates priority inversion at the cost of reduced throughput. The slack stealing query scheduling algorithm combines the benefits of preemptive and non-preemptive …

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Extending Bpel For Interoperable Pervasive Computing, Gregory Hackmann, Christopher Gill, Christopher Gill, Gruia-Catalin Roman Jan 2007

Extending Bpel For Interoperable Pervasive Computing, Gregory Hackmann, Christopher Gill, Christopher Gill, Gruia-Catalin Roman

All Computer Science and Engineering Research

The widespread deployment of mobile devices like PDAs and mobile phones has created a vast computation and communication platform for pervasive computing applications. However, these devices feature an array of incompatible hardware and software architectures, discouraging ad-hoc interactions among devices. The Business Process Execution Language (BPEL) allows users in wired computing settings to model applications of significant complexity, leveraging Web standards to guarantee interoperability. However, BPEL's inflexible communication model effectively prohibits its deployment on the kinds of dynamic wireless networks used by most pervasive computing devices. This paper presents extensions to BPEL that address these restrictions, transforming BPEL into a …

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The Effect Of Object Color On Depth Ordering, Reynold Bailey, Cindy Grimm, Christopher Davoli, Richard Abrams Jan 2007

The Effect Of Object Color On Depth Ordering, Reynold Bailey, Cindy Grimm, Christopher Davoli, Richard Abrams

All Computer Science and Engineering Research

The relationship between color and perceived depth for realistic, colored objects with varying shading was explored. Background: Studies have shown that warm-colored stimuli tend to appear nearer in depth than cool-colored stimuli. The majority of these studies 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 were typically highly saturated. Although such stimuli are useful for isolating and studying depth cues in certain contexts, they leave …

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Emergent Task Allocation For Mobile Robots Through Intentions And Directives, Nuzhet Atay, Burchan Bayazit Jan 2007

Emergent Task Allocation For Mobile Robots Through Intentions And Directives, 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. However, algorithms that find the optimal solution are usually computationally expensive and may require a large number of messages between the robots as the robots need to be aware of the global spatiotemporal information. In this paper, we introduce an emergent task allocation approach for mobile robots. Each robot uses only the information obtained from its immediate neighbors in its decision. Our technique is general enough to be applicable to any task allocation scheme as long as a utilization criteria is given. We demonstrate that our approach …

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Splice: A Standardized Peripheral Logic And Interface Creation Engine, Justin Thiel Jan 2007

Splice: A Standardized Peripheral Logic And Interface Creation Engine, Justin Thiel

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Recent advancements in FPGA technology have allowed manufacturers to place general-purpose processors alongside user-configurable logic gates on a single chip. At first glance, these integrated devices would seem to be the ideal deployment platform for hardware-software co-designed systems, but some issues, such as incompatibility across vendors and confusion over which bus interfaces to support, have impeded adoption of these platforms. This thesis describes the design and operation of Splice, a software-based code generation tool intended to address these types of issues by providing a bus-independent structure that allows end-users to easily integrate their customized peripheral logic into embedded systems. To …

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Splice: A Standardized Peripheral Logic And Interface Creation Engine, Master's Thesis, May 2007, Justin Thiel Jan 2007

Splice: A Standardized Peripheral Logic And Interface Creation Engine, Master's Thesis, May 2007, Justin Thiel

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Recent advancements in FPGA technology have allowed manufacturers to place general-purpose processors alongside user-configurable logic gates on a single chip. At first glance, these integrated devices would seem to be the ideal deployment platform for hardware-software co-designed systems, but some issues, such as incompatibility across vendors and confusion over which bus interfaces to support, have impeded adoption of these platforms. This thesis describes the design and operation of Splice, a software-based code generation tool intended to address these types of issues by providing a bus-independent structure that allows end-users to easily integrate their customized peripheral logic into embedded systems. To …

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Price Of Asynchrony: Queuing Under Ideally Smooth Congestion Control, Maxim Podlesny, Sergey Gorinsky Jan 2007

Price Of Asynchrony: Queuing Under Ideally Smooth Congestion Control, Maxim Podlesny, Sergey Gorinsky

All Computer Science and Engineering Research

The ability of TCP (Transmission Control Protocol) or alternative congestion control algorithms to operate successfully in networks with small link buffers has recently become a subject of intensive research. In this paper, we investigate fundamental limitations on minimum buffer requirements for any congestion control. We present an idealized protocol where all flows always transmit at their fair rates. The ideally smooth congestion control causes link queuing only due to asynchrony of flow arrivals, which is intrinsic to computer networks. Our analysis and simulations for different distributions of flow interarrival times agree that the buffer size needed for a fixed loss …

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Architecture For Document Clustering In Reconfigurable Hardware, Master's Thesis, December 2006, Adam G. Covington Jan 2007

Architecture For Document Clustering In Reconfigurable Hardware, Master's Thesis, December 2006, Adam G. Covington

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High-performance document clustering systems enable similar documents to automatically self-organize into groups. In the past, the large amount of computational time needed to cluster documents prevented practical use of such systems with a large number of documents. A full hardware implementation of K-means clustering has been designed and implemented in reconfigurable hardware that rapidly clusters a half million documents. Documents and concepts are represented as vectors with 4000 dimensions. The circuit was implemented in Field Programmable Gate Array (FPGA) logic and uses four parallel cosine distance metrics to cluster document vectors together. An exploration of the effect of the integer …

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Hexa: Compact Data Structures For Faster Packet Processing, Sailesh Kumar, Jonathan Turner, Patrick Crowley, Michael Mitzenmacher Jan 2007

Hexa: Compact Data Structures For Faster Packet Processing, Sailesh Kumar, Jonathan Turner, Patrick Crowley, Michael Mitzenmacher

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Directed graphs with edge labels are used in packet processing algorithms for a variety of network applications. In this paper we present a novel representation for such graph that significantly reduces the memory required for such graphs. This approach called History-based Encoding, eXecution and Addressing (HEXA) challenges the conventional assumption that graph data structures must store pointers of log2n bits to identify successor nodes. HEXA takes advantage of implict information to reduce the information that must be stored explicitly. We demonstrate that the binary tries used for IP route lookup can be implemented using just two bytes per stored prefix …

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Improving Individual Flow Performance With Multiple Queue Fair Queuing, Manfred Georg, Christopher Jechlitschek, Sergey Gorinsky Jan 2007

Improving Individual Flow Performance With Multiple Queue Fair Queuing, Manfred Georg, Christopher Jechlitschek, Sergey Gorinsky

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Fair Queuing (FQ) algorithms provide isolation between packet flows, allowing max-min fair sharing of a link even when flows misbehave. However, fairness comes at the expense of per-flow state. To keep the memory requirement independent of the flow count, the router can isolate aggregates of flows, rather than individual flows. We investigate the feasibility of protecting individual flows under such aggregate isolation in the context of Multiple Queue Fair Queuing (MQFQ), where the router maintains a fixed number of queues and associates multiple queues with each flow. MQFQ places packets in the shortest queue associated with their flow. The redundancy …

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Single Cell Expression Profiling Reveals Major Disruption Of Dna Repair Capacity In Incipient Alzheimer's Disease, Monika Ray, Weixiong Zhang Jan 2007

Single Cell Expression Profiling Reveals Major Disruption Of Dna Repair Capacity In Incipient Alzheimer's Disease, Monika Ray, Weixiong Zhang

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Understanding the pathogenesis in the early stages of late-onset Alzheimer's disease (LOAD) can help in gaining important mechanistic insights into this devastating neurodegenerative disorder. Alzheimer's disease (AD) is characterised by extensive cell death with disease progression. In this paper laser capture microdissection (LCM) based gene expression profiling, which is able to profile gene expression in a single cell type, is employed to analyse the gene expression regulation of incipient AD. Our analysis shows that LCM based gene expression profiling of neurons has a critical advantage over the conventional gene expression profiling method which uses samples of mixed cell types and …

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Implementing Legba: Fine-Grained Memory Protection, Sheffield, Sowell, Wilson Jan 2007

Implementing Legba: Fine-Grained Memory Protection, Sheffield, Sowell, Wilson

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Fine-grained hardware protection could provide a powerful and effective means for isolating untrusted code. However, previous techniques for providing fine-grained protection in hardware have lead to poor performance. Legba has been proposed as a new caching architecture, designed to reduce the granularity of protection, without slowing down the processor. Unfortunately, the designers of Legba have not attempted an implementation. Instead, all of their analysis is based purely on simulations. We present an implementation of the Legba design on a MIPS Core Processor, along with an analysis of our observations and results.

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Configuring Low Cost Metanetworks On A Shared Substrate, Jing Lu, Jonathan Turner Jan 2007

Configuring Low Cost Metanetworks On A Shared Substrate, Jing Lu, Jonathan Turner

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In a diversified internet, meta-networks (“metanets?for short) share a common substrate and offer value-added services to millions of users around the globe. Therefore, configuring low-cost metanets with links having enough bandwidth to accommodate all anticipated user traffic is critical to the success of the metanets. In this paper, we propose a novel pruning algorithm that configures metanets on any given substrate in a cost-efficient way. In contrast to other testbed configuration systems, we solve the metanet configuration problem from a higher level specification and produces a network that is dimensioned to handle the specified traffic. To the best of our …

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Mobile Wireless Sensor Network Connectivity Repair With K-Redundanc, Nuzhet Atay, Burchan Bayazit Jan 2007

Mobile Wireless Sensor Network Connectivity Repair With K-Redundanc, Nuzhet Atay, Burchan Bayazit

All Computer Science and Engineering Research

Connectivity is an important requirement for wireless sensor networks especially in real-time monitoring and data transfer applications. However, node movements and failures change the topology of the initial deployed network, which can result in partitioning of the communication graph. In this paper, we present a method for maintaining and repairing the communication network of a dynamic mobile wireless sensor network. We assume that we cannot control the motion of wireless sensor nodes, but there are robots whose motion can be controlled by the wireless sensor nodes to maintain and repair the connectivity of the network. At the heart of our …

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Leveraging Est Evidence To Automatically Predict Alternatively Spliced Genes, Master's Thesis, December 2006, Robert Zimmermann Jan 2007

Leveraging Est Evidence To Automatically Predict Alternatively Spliced Genes, Master's Thesis, December 2006, Robert Zimmermann

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Current methods for high-throughput automatic annotation of newly sequenced genomes are largely limited to tools which predict only one transcript per gene locus. Evidence suggests that 20-50% of genes in higher eukariotic organisms are alternatively spliced. This leaves the remainder of the transcripts to be annotated by hand, an expensive time-consuming process. Genomes are being sequenced at a much higher rate than they can be annotated. We present three methods for using the alignments of inexpensive Expressed Sequence Tags in combination with HMM-based gene prediction with N-SCAN EST to recreate the vast majority of hand annotations in the D.melanogaster genome. …

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Strong Performance Guarantees For Asynchronous Buffered Crossbar Schedulers, Jonathon Turner Jan 2007

Strong Performance Guarantees For Asynchronous Buffered Crossbar Schedulers, Jonathon Turner

All Computer Science and Engineering Research

Crossbar-based switches are commonly used to implement routers with throughputs up to about 1 Tb/s. The advent of crossbar scheduling algorithms that provide strong performance guarantees now makes it possible to engineer systems that perform well, even under extreme traffic conditions. Until recently, such performance guarantees have only been developed for crossbars that switch cells rather than variable length packets. Cell-based crossbars incur a worst-case bandwidth penalty of up to a factor of two, since they must fragment variable length packets into fixed length cells. In addition, schedulers for cell-based crossbars may fail to deliver the expected performance guarantees when …

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Gigabit Concept Mining: A Sensitivity Analysis, Masters Thesis, December 2006, Andrew Levine Jan 2007

Gigabit Concept Mining: A Sensitivity Analysis, Masters Thesis, December 2006, Andrew Levine

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Massive amounts of data are passed over public networks. There is a need for network administrators to analyze this traffic, but it was not previously possible to analyze live network data at high speed. It has been shown that streaming computation and deep packet analysis are possible at very high rates through the use of hardware acceleration. This work provides analysis for a larger project that involves digesting large amounts of network traffic. In this system, we process the traffic using hardware that has constraints. The workings of the system are first discussed. Tradeoffs in the design of hardware and …

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