Virginia Tech

Displaying 1-40 of 70 results

  • White Papers // Sep 2011

    An Anti-Jamming Strategy for Channel Access in Cognitive Radio Networks

    The authors address an anti-jamming strategy of channel access for secondary user in a cognitive radio network when some idle channels of the primary user are being jammed in each time slot. Given the secondary does not know what idle bands are under attack, using their method it tries to...

    Provided By Virginia Tech

  • White Papers // Jul 2011

    K2C: Cryptographic Cloud Storage With Lazy Revocation and Anonymous Access

    Security and privacy concerns hinder the adoption of cloud storage and computing in sensitive environments. The authors present a user-centric privacy-preserving cryptographic access control protocol called K2C (Key To Cloud) that enables end-users to securely store, share, and manage their sensitive data in untrusted cloud storage anonymously. K2C is scalable...

    Provided By Virginia Tech

  • White Papers // Jun 2011

    Preemption, Fairness, and Security Dynamics in Heterogeneous DSA Environments

    In this paper, the authors study how key dynamic spectrum access operating parameters impact radios' ability to fairly access wireless spectrum. Additionally they investigate intentional spectrum access policies that allow priority radios (e.g. public safety or defense) to preempt access to the spectrum by lower priority (e.g. commercial) radio networks....

    Provided By Virginia Tech

  • White Papers // Jun 2011

    Space-Time Network Coding With Optimal Node Selection for Amplify-and-Forward Cooperative Networks

    In a wireless network with multiple Amplify-and-Forward (AF) nodes, the many-to-many cooperative communication is achieved through the novel concept of Space-Time Network Coding with Optimal Node Selection (STNC-ONS). The communication under the STNC-ONS scheme is split into two phases: the Broadcasting Phase (BP) in which each node in its allocated...

    Provided By Virginia Tech

  • White Papers // May 2011

    Completely Distributed Particle Filters for Target Tracking in Sensor Networks

    Particle Filters (or PFs) are widely used for the tracking problem in dynamic systems. Despite their remarkable tracking performance and flexibility, PFs require intensive computation and communication, which are strictly constrained in Wireless Sensor Networks (or WSNs). Thus, Distributed Particle Filters (or DPFs) have been studied to distribute the computational...

    Provided By Virginia Tech

  • White Papers // Mar 2011

    Optimal Power Control for Multi-Hop Software Defined Radio Networks

    Software Defined Radio (SDR) is a revolution in radio technology that promises unprecedented flexibility in radio communications and is viewed as an enabling technology for dynamic spectrum access. This paper investigates how to support user communication sessions by jointly considering power control, scheduling, and flow routing for an SDR-based multi-hop...

    Provided By Virginia Tech

  • White Papers // Mar 2011

    CATCH: A Cloud-Based Adaptive Data Transfer Service for HPC

    Modern High Performance Computing (HPC) applications process very large amounts of data. A critical research challenge lies in transporting input data to the HPC center from a number of distributed sources, e.g., scientific experiments and web repositories, etc., and offloading the result data to geographically distributed, intermittently available end-users, often...

    Provided By Virginia Tech

  • White Papers // Mar 2011

    Timing-And Termination-Sensitive Secure Information Flow: Exploring a New Approach

    Secure information flow guarantees the secrecy and integrity of data, preventing an attacker from learning secret information (secrecy) or injecting untrusted information (integrity). Covert channels can be used to subvert these security guarantees; for example, timing and termination channels can, either intentionally or inadvertently, violate these guarantees by modifying the...

    Provided By Virginia Tech

  • White Papers // Feb 2011

    Verification and Validation of Smartphone Sensor Networks

    This paper introduces a subset of mobile wireless sensor networks, called smartphone sensor networks, where large numbers of smartphone devices cooperate to perform sensing tasks. While these emerging networks show high potential, little work has been done on design-time verification and validation to ensure that a designed system will meet...

    Provided By Virginia Tech

  • White Papers // Feb 2011

    Multitouch Tables for Collaborative Object-Based Learning

    Multitouch technology on tabletop displays allows children to interact with digital objects in collaborative activities. This paper explores both evolutions in hardware and opportunities in software toward supporting the engagement of children, with consideration of impact on user interfaces. The authors outline a demonstration of the Multitouch Education Table (MET),...

    Provided By Virginia Tech

  • White Papers // Jan 2011

    Theoretical Results on Base Station Movement Problem for Sensor Networks

    The benefits of using mobile base station to prolong sensor network lifetime have been well recognized. However, due to the complexity of the problem (time-dependent network topology and traffic routing), theoretical performance limit and provably optimal algorithms remain difficult to develop. This paper fills this important gap by contributing theoretical...

    Provided By Virginia Tech

  • White Papers // Jan 2011

    Compositional Specification and Realization of Mixed-Initiative Web Dialogs

    The authors present DialogXML a markup language approach to specifying and realizing mixed-initiative web dialogs on mobile devices. By capturing the functional structure of the dialog independent of the modalities used to realize it, DialogXML facilitates the implementation of web interfaces that integrate hyperlink and speech modes of interaction. It...

    Provided By Virginia Tech

  • White Papers // Jan 2011

    Formalizing the Interference Temperature Model

    To combat recent spectral overcrowding in unlicensed bands, the FCC has been investigating new ways to manage RF resources. The idea is to let people use licensed frequencies, provided they can guarantee interference perceived by the primary license holders will be minimal. With advances in software and cognitive radio, practical...

    Provided By Virginia Tech

  • White Papers // Jan 2011

    MeshTest: Laboratory-Based Wireless Testbed for Large Topologies

    Mobile, ad-hoc, wireless networks offer an interesting paradigm for ubiquitous connectivity. They have many proposed applications, and with every application come new protocols. To test such protocols, one has two basic options: simulators and testbeds. The authors describe a novel wireless networks testbed called MeshTest, supporting mobile, ad-hoc, and mesh...

    Provided By Virginia Tech

  • White Papers // Jan 2011

    Securing RFID With Ultra-Wideband Modulation

    Current implementations of secure RFID rely on digital cryptographic primitives in the form of hashes and block ciphers. The presence of these blocks is motivated by privacy requirements, but they increase the overall processing latency, the power consumption, and the silicon area budget of the RFID tag. In addition, existing...

    Provided By Virginia Tech

  • White Papers // Jan 2011

    Process Isolation for Reconfigurable Hardware

    One of the pillars of trustworthy computing is process isolation, the ability to keep process data private from other processes running on the same device. While embedded operating systems provide isolation for the software part of these processes, there is no commonly accepted isolation mechanism for the hardware resources. As...

    Provided By Virginia Tech

  • White Papers // Jan 2011

    Offline HW/SW Authentication for Reconfigurable Platforms

    Many Field-Programmable Gate Array (FPGA) based systems utilize third-party Intellectual Property (IP) in their development. When they are deployed in non-networked environments, the question raises how this IP can be protected against non-authorized use. The authors describe an offline authentication scheme for IP modules. The scheme implements mutual authentication of...

    Provided By Virginia Tech

  • White Papers // Jan 2011

    Design With Race-Free Hardware Semantics

    Most hardware description languages do not enforce determinacy, meaning that they may yield races. Race conditions pose a problem for the implementation, verification, and validation of hardware. Enforcing determinacy at the modeling level provides a solution to this problem. In this paper, the authors consider a common model of computation...

    Provided By Virginia Tech

  • White Papers // Dec 2010

    Maintainable and Reusable Scientific Software Adaptation

    Scienti c software must be adapted for different execution environments, problem sets, and available resources to ensure its efficiency and reliability. Although adaptation patterns can be found in a sizable percentage of recent scientific applications, the traditional scientific software stack lacks the adequate adaptation abstractions and tools. As a result,...

    Provided By Virginia Tech

  • White Papers // Nov 2010

    Enabling Renewed Innovation in TCP by Establishing an Isolation Boundary

    The growth of the Internet has ushered in and established the "Information Age". However, its success has also arguably increased the difficulty of incorporating innovative changes that are needed to develop further functionality for next-generation networked applications. From the transport perspective, the desired functionality includes supporting multiple network paths, providing...

    Provided By Virginia Tech

  • White Papers // Nov 2010

    Enhancing MapReduce Via Asynchronous Data Processing

    The MapReduce programming model simplifies large-scale data processing on commodity clusters by having users specify a map function that processes input key/value pairs to generate intermediate key/value pairs, and a reduce function that merges and converts intermediate key/value pairs into final results. Typical MapReduce implementations such as Hadoop enforce barrier...

    Provided By Virginia Tech

  • White Papers // Oct 2010

    Power Efficient Coded 4-PAM OFDM for High Rate Data Links

    Orthogonal Frequency Division Multiplexing (OFDM) is one of the best solutions for wideband communication applications. M-ary PAM - OFDM achieves comparable power and bandwidth efficiencies with less system complexity to ordinary OFDM systems that use M-ary QAM or M-ary PSK. Basically, OFDM is sensitive to Carrier Frequency Offset (CFO) and...

    Provided By Virginia Tech

  • White Papers // Oct 2010

    User-Behavior Based Detection of Infection Onset

    A major vector of computer infection is through exploiting software or design flaws in networked applications such as the browser. Malicious code can be fetched and executed on a victim's machine without the user's permission, as in Drive-By Download (DBD) attacks. In this paper, the authors describe a new tool...

    Provided By Virginia Tech

  • White Papers // Oct 2010

    CampProf: A Visual Performance Analysis Tool for Memory Bound GPU Kernels

    Current GPU tools and performance models provide some common architectural insights that guide the programmers to write optimal code. The authors challenge these performance models, by modeling and analyzing a lesser known, but very severe performance pitfall, called 'Partition Camping', in NVIDIA GPUs. Partition Camping is caused by memory accesses...

    Provided By Virginia Tech

  • White Papers // Sep 2010

    Reusable Software Components for Accelerator-Based Clusters

    The emerging accelerator-based heterogeneous clusters, comprising specialized processors such as the IBM Cell and GPUs, have exhibited excellent price to performance ratio as well as high energy-efficiency. However, developing and maintaining software for such systems is fraught with challenges, especially for modern High-Performance Computing (HPC) applications that can benefit the...

    Provided By Virginia Tech

  • White Papers // Sep 2010

    Early and Often: Bringing More Parallelism Into Undergraduate Computer Science Curricula

    In view of recent industry shifts towards both multi-core processors and applications of distributed computing through techniques such as map-reduce, the question naturally arises: how can Computer Science (CS) undergraduate programs respond with curricular changes to prepare their students for the future of computation, in which parallelism and concurrency will...

    Provided By Virginia Tech

  • White Papers // Aug 2010

    Strategies for Preparing Computer Science Students for the Multicore World

    The authors are motivated to teach more parallelism and concurrency in CS courses because of the necessary shift by hardware manufacturers towards multi-core computer design. For over four decades, hardware performance has improved at an exponential rate, a remarkable feat that derives from ever increasing miniaturization of transistor components. Since...

    Provided By Virginia Tech

  • White Papers // Jul 2010

    Dynamic Software Updates for Parallel High Performance Applications

    Despite using multiple concurrent processors, a typical high performance parallel application is long-running, taking hours, even days to arrive at a solution. To modify a running high performance parallel application, the programmer has to stop the computation, change the code, redeploy, and enqueue the updated version to be scheduled to...

    Provided By Virginia Tech

  • White Papers // Jul 2010

    A First Look at Integrated GPUs for Green High-Performance Computing

    The Graphics Processing Unit (GPU) has evolved from a single-purpose graphics accelerator to a tool that can greatly accelerate the performance of High-Performance Computing (HPC) applications. Previous work evaluated the energy efficiency of discrete GPUs for compute-intensive scientific computing and found them to be energy efficient but very high power....

    Provided By Virginia Tech

  • White Papers // Jun 2010

    Detecting the Onset of Infection for Secure Hosts

    Software flaws in applications such as a browser may be exploited by attackers to launch Drive-By-Download (DBD), which has be-come the major vector of malware infection. The authors describe a host-based detection approach against DBDs by correlating the behaviors of human-user related to file systems. The approach involves capturing keyboard...

    Provided By Virginia Tech

  • White Papers // May 2010

    On the Goodput of TCP NewReno in Mobile Networks

    Next-generation wireless networks such as LTE and WiMax can achieve throughputs of several Mbps with TCP. These higher throughputs, however, can easily be destroyed by frequent handoffs, which occur in urban environments due to shadowing. A primary reason for the throughput drop during handoffs is the out of order arrival...

    Provided By Virginia Tech

  • White Papers // Apr 2010

    MOON: MapReduce on Opportunistic eNvironments

    MapReduce offers an ease-of-use programming paradigm for processing large data sets, making it an attractive model for distributed volunteer computing systems. However, unlike on dedicated resources, where MapReduce has mostly been deployed, such volunteer computing systems have significantly higher rates of node unavailability. Furthermore, nodes are not fully controlled by...

    Provided By Virginia Tech

  • White Papers // Apr 2010

    Knowing Where Your Input Is From: Kernel-Level Data-Provenance Verification

    This paper describes a cryptographic provenance verification approach for ensuring system properties and system-data integrity at kernel-level. Its two concrete applications are demonstrated in malware traffic detection and keystroke-based bot identification. Specifically, the authors first demonstrate the provenance verification approach by realizing a lightweight framework for blocking outbound malware traffic....

    Provided By Virginia Tech

  • White Papers // Apr 2010

    Emerging From the MIST: A Connector Tool for Supporting Programming by Non-Programmers

    Software development is an iterative process. As user requirements emerge software applications must be extended to support the new requirements. Typically, a programmer will add new code to an existing code base of an application to provide a new functionality. Previous research has shown that such extensions are easier when...

    Provided By Virginia Tech

  • White Papers // Mar 2010

    On Multihop Broadcast Over Adaptively Duty-Cycled Wireless Sensor Networks

    The authors consider the problem of multi-hop broadcast over adaptively duty-cycled Wireless Sensor Networks (WSNs) where neighborhood nodes are not simultaneously awake. They present Hybrid-cast, an asynchronous and multi-hop broadcasting protocol, which can be applied to low duty-cycling or quorum-based duty-cycling schedule where nodes send out a beacon message at...

    Provided By Virginia Tech

  • White Papers // Mar 2010

    Inter-Block GPU Communication Via Fast Barrier Synchronization

    While GPGPU stands for General-Purpose computation on Graphics Processing Units, the lack of explicit support for inter-block communication on the GPU arguably hampers its broader adoption as a general-purpose computing device. Inter-block communication on the GPU occurs via global memory and then requires barrier synchronization across the blocks, i.e., inter-block...

    Provided By Virginia Tech

  • White Papers // Mar 2010

    To GPU Synchronize or Not GPU Synchronize?

    The Graphics Processing Unit (GPU) has evolved from being a fixed-function processor with programmable stages into a programmable processor with many fixed-function components that deliver massive parallelism. By modifying the GPU's stream processor to support "General-purpose Computation" on the GPU (GPGPU), applications that perform massive vector operations can realize many...

    Provided By Virginia Tech

  • White Papers // Feb 2010

    Understanding the Tenets of Agile Software Engineering: Lecturing, Exploration and Critical Thinking

    The use of agile principles and practices in software development is becoming a powerful force in today's workplace. In the authors' quest to develop better products, therefore, it is imperative that they strive to learn and understand the application of Agile methods, principles and techniques to the software development enterprise....

    Provided By Virginia Tech

  • White Papers // Jan 2010

    Reusable Enterprise Metadata With Pattern-Based Structural Expressions

    An essential part of modern enterprise software development is metadata. Mainstream metadata formats, including XML deployment descriptors and Java 5 annotations, suffer from a number of limitations that complicate the development and maintenance of enterprise applications. Their key problem is that they make it impossible to reuse metadata specifications not...

    Provided By Virginia Tech

  • White Papers // Dec 2009

    Cooperative Communications in Multi-Hop Wireless Networks: Joint Flow Routing and Relay Node Assignment

    It has been shown that Cooperative Communications (CC) have the potential to significantly increase the capacity of wireless networks. However, most of the existing results are limited to single-hop wireless networks. To illustrate the benefits of CC in multi-hop wireless networks, the authors solve a joint optimization problem of relay...

    Provided By Virginia Tech

  • White Papers // May 2009

    Increasing the Sensitivity of On-Chip Digital Thermal Sensors With Pre-Filtering

    Thermal monitoring has been broadly used to protect high-end integrated circuits from over-heating and to identify hot-spots in complex circuits. In this paper, the authors present a method to increase the sensitivity of an on-chip digital thermal sensor. In contrast to the existing mechanisms that characterize the overall temperature profile...

    Provided By Virginia Tech

  • White Papers // Nov 2008

    Comparing Gesture and Touch for Notification System Interactions

    The authors explore some of the characteristics of multimodal input interaction spaces for notification systems within a multi-tasking environment like a command and control center using two promising interaction methods: gestures and touch based input through a laboratory experiment comparing both techniques. Results of the study suggest that gestures are...

    Provided By Virginia Tech

  • White Papers // Feb 2011

    Multitouch Tables for Collaborative Object-Based Learning

    Multitouch technology on tabletop displays allows children to interact with digital objects in collaborative activities. This paper explores both evolutions in hardware and opportunities in software toward supporting the engagement of children, with consideration of impact on user interfaces. The authors outline a demonstration of the Multitouch Education Table (MET),...

    Provided By Virginia Tech

  • White Papers // Mar 2011

    Optimal Power Control for Multi-Hop Software Defined Radio Networks

    Software Defined Radio (SDR) is a revolution in radio technology that promises unprecedented flexibility in radio communications and is viewed as an enabling technology for dynamic spectrum access. This paper investigates how to support user communication sessions by jointly considering power control, scheduling, and flow routing for an SDR-based multi-hop...

    Provided By Virginia Tech

  • White Papers // May 2008

    Culturally Infused Social Network Analysis

    Social networks are an important way to represent and analyze social phenomena. One aspect that is critical in order to provide relevant and useful analyses is the capability to infuse culture systematically. Cultural elements are typically either lacking or implicitly (and sometimes unintentionally) embedded in social network construction. Thus, current...

    Provided By Virginia Tech

  • White Papers // Aug 2010

    Strategies for Preparing Computer Science Students for the Multicore World

    The authors are motivated to teach more parallelism and concurrency in CS courses because of the necessary shift by hardware manufacturers towards multi-core computer design. For over four decades, hardware performance has improved at an exponential rate, a remarkable feat that derives from ever increasing miniaturization of transistor components. Since...

    Provided By Virginia Tech

  • White Papers // Sep 2010

    Early and Often: Bringing More Parallelism Into Undergraduate Computer Science Curricula

    In view of recent industry shifts towards both multi-core processors and applications of distributed computing through techniques such as map-reduce, the question naturally arises: how can Computer Science (CS) undergraduate programs respond with curricular changes to prepare their students for the future of computation, in which parallelism and concurrency will...

    Provided By Virginia Tech

  • White Papers // May 2008

    On Scalable Synchronization for Distributed Embedded Real-Time Systems

    The authors consider the problem of programming distributed embedded real-time systems with distributed dependencies. They show that the de facto standard of using locks and condition variables in conjunction with threads can have significant overhead and semantic difficulty and suggest alternative programming abstractions to alleviate these problems. They also discuss...

    Provided By Virginia Tech

  • White Papers // Jan 2011

    Theoretical Results on Base Station Movement Problem for Sensor Networks

    The benefits of using mobile base station to prolong sensor network lifetime have been well recognized. However, due to the complexity of the problem (time-dependent network topology and traffic routing), theoretical performance limit and provably optimal algorithms remain difficult to develop. This paper fills this important gap by contributing theoretical...

    Provided By Virginia Tech

  • White Papers // Jul 2011

    K2C: Cryptographic Cloud Storage With Lazy Revocation and Anonymous Access

    Security and privacy concerns hinder the adoption of cloud storage and computing in sensitive environments. The authors present a user-centric privacy-preserving cryptographic access control protocol called K2C (Key To Cloud) that enables end-users to securely store, share, and manage their sensitive data in untrusted cloud storage anonymously. K2C is scalable...

    Provided By Virginia Tech

  • White Papers // Jun 2011

    Space-Time Network Coding With Optimal Node Selection for Amplify-and-Forward Cooperative Networks

    In a wireless network with multiple Amplify-and-Forward (AF) nodes, the many-to-many cooperative communication is achieved through the novel concept of Space-Time Network Coding with Optimal Node Selection (STNC-ONS). The communication under the STNC-ONS scheme is split into two phases: the Broadcasting Phase (BP) in which each node in its allocated...

    Provided By Virginia Tech

  • White Papers // Oct 2010

    Power Efficient Coded 4-PAM OFDM for High Rate Data Links

    Orthogonal Frequency Division Multiplexing (OFDM) is one of the best solutions for wideband communication applications. M-ary PAM - OFDM achieves comparable power and bandwidth efficiencies with less system complexity to ordinary OFDM systems that use M-ary QAM or M-ary PSK. Basically, OFDM is sensitive to Carrier Frequency Offset (CFO) and...

    Provided By Virginia Tech

  • White Papers // Mar 2011

    CATCH: A Cloud-Based Adaptive Data Transfer Service for HPC

    Modern High Performance Computing (HPC) applications process very large amounts of data. A critical research challenge lies in transporting input data to the HPC center from a number of distributed sources, e.g., scientific experiments and web repositories, etc., and offloading the result data to geographically distributed, intermittently available end-users, often...

    Provided By Virginia Tech

  • White Papers // Feb 2011

    Verification and Validation of Smartphone Sensor Networks

    This paper introduces a subset of mobile wireless sensor networks, called smartphone sensor networks, where large numbers of smartphone devices cooperate to perform sensing tasks. While these emerging networks show high potential, little work has been done on design-time verification and validation to ensure that a designed system will meet...

    Provided By Virginia Tech

  • White Papers // May 2011

    Completely Distributed Particle Filters for Target Tracking in Sensor Networks

    Particle Filters (or PFs) are widely used for the tracking problem in dynamic systems. Despite their remarkable tracking performance and flexibility, PFs require intensive computation and communication, which are strictly constrained in Wireless Sensor Networks (or WSNs). Thus, Distributed Particle Filters (or DPFs) have been studied to distribute the computational...

    Provided By Virginia Tech

  • White Papers // Mar 2010

    On Multihop Broadcast Over Adaptively Duty-Cycled Wireless Sensor Networks

    The authors consider the problem of multi-hop broadcast over adaptively duty-cycled Wireless Sensor Networks (WSNs) where neighborhood nodes are not simultaneously awake. They present Hybrid-cast, an asynchronous and multi-hop broadcasting protocol, which can be applied to low duty-cycling or quorum-based duty-cycling schedule where nodes send out a beacon message at...

    Provided By Virginia Tech

  • White Papers // Sep 2008

    CQS-Pair: Cyclic Quorum System Pair for Wakeup Scheduling in Wireless Sensor Networks

    Due to the heterogeneous power-saving requirement in wireless sensor networks, the authors propose the Cyclic Quorum System Pair (CQS-Pair) which can guarantee that two asynchronous nodes adopting different cyclic quorum systems can hear each other at least once in bounded time intervals. To quickly assemble a CQS-Pair, the authors present...

    Provided By Virginia Tech

  • White Papers // Jun 2008

    SOQ: A Service-Oriented Quorum-Based Protocol for Resilient Real-Time Communication in Partitionable Networks

    The authors consider efficient real-time communication mechanisms for applications in unreliable and partitionable networks, where network partitions can occur unpredictably and nodes can join and leave arbitrarily. Utilizing quorum systems, they present a quorum-based protocol called SOQ to let nodes update and query service information to a selected set of...

    Provided By Virginia Tech

  • White Papers // Jul 2008

    On a Self-Organizing MANET Event Routing Architecture With Causal Dependency Awareness

    Publish/Subscribe (P/S) is a communication paradigm of growing popularity for information dissemination in large-scale distributed systems. The strong decoupling between information producers and consumers in P/S systems is attractive for loosely coupled and dynamic network infrastructures such as Mobile Ad hoc NETworks (MANETs). However, achieving end-to-end timeliness and reliability properties...

    Provided By Virginia Tech

  • White Papers // May 2008

    Rate Allocation With Lifetime Maximization and Fairness for Data Aggregation in Sensor Networks

    The authors consider the rate allocation problem for data aggregation in wireless sensor networks with two objectives: maximizing the lifetime of a local aggregation cluster and achieving fairness among all data sources. The two objectives are generally correlated with each other and usually they cannot be maximized simultaneously. They adopt...

    Provided By Virginia Tech

  • White Papers // May 2009

    Mergers With Innovation In Differentiated Product Industries: The Case Of The Supercomputers

    This paper studies the effects of mergers in the supercomputer market. The starting point is a discrete-choice demand model for differentiated products. The author incorporates the demand model into an estimable dynamic oligopoly model, in which multi product firms decide on entry, exit and innovation rate targets while making static...

    Provided By Virginia Tech

  • White Papers // Apr 2010

    MOON: MapReduce on Opportunistic eNvironments

    MapReduce offers an ease-of-use programming paradigm for processing large data sets, making it an attractive model for distributed volunteer computing systems. However, unlike on dedicated resources, where MapReduce has mostly been deployed, such volunteer computing systems have significantly higher rates of node unavailability. Furthermore, nodes are not fully controlled by...

    Provided By Virginia Tech

  • White Papers // Apr 2009

    Method of High-Speed Data Acquisition and Continuous Data Transfer Using Altera Stratix II EP2S60 DSP Development Board

    Ethernet has become a standard data transport paradigm for embedded systems in many applications since the transport technology is cheap, abundant, mature and reliable. This paper has implemented an Altera Nios II based system for data acquisition and transfer over Ethernet using User Datagram Protocol (UDP). The network client (The...

    Provided By Virginia Tech

  • White Papers // Mar 2010

    To GPU Synchronize or Not GPU Synchronize?

    The Graphics Processing Unit (GPU) has evolved from being a fixed-function processor with programmable stages into a programmable processor with many fixed-function components that deliver massive parallelism. By modifying the GPU's stream processor to support "General-purpose Computation" on the GPU (GPGPU), applications that perform massive vector operations can realize many...

    Provided By Virginia Tech

  • White Papers // Mar 2010

    Inter-Block GPU Communication Via Fast Barrier Synchronization

    While GPGPU stands for General-Purpose computation on Graphics Processing Units, the lack of explicit support for inter-block communication on the GPU arguably hampers its broader adoption as a general-purpose computing device. Inter-block communication on the GPU occurs via global memory and then requires barrier synchronization across the blocks, i.e., inter-block...

    Provided By Virginia Tech

  • White Papers // May 2010

    On the Goodput of TCP NewReno in Mobile Networks

    Next-generation wireless networks such as LTE and WiMax can achieve throughputs of several Mbps with TCP. These higher throughputs, however, can easily be destroyed by frequent handoffs, which occur in urban environments due to shadowing. A primary reason for the throughput drop during handoffs is the out of order arrival...

    Provided By Virginia Tech

  • White Papers // Jul 2010

    A First Look at Integrated GPUs for Green High-Performance Computing

    The Graphics Processing Unit (GPU) has evolved from a single-purpose graphics accelerator to a tool that can greatly accelerate the performance of High-Performance Computing (HPC) applications. Previous work evaluated the energy efficiency of discrete GPUs for compute-intensive scientific computing and found them to be energy efficient but very high power....

    Provided By Virginia Tech

  • White Papers // Dec 2009

    On the Robust Mapping of Dynamic Programming Onto a Graphics Processing Unit

    Graphics Processing Units (GPUs) have been widely used to accelerate algorithms that exhibit massive data parallelism or task parallelism. When such parallelism is not inherent in an algorithm, computational scientists resort to simply replicating the algorithm on every multiprocessor of a NVIDIA GPU, for example, to create such parallelism, resulting...

    Provided By Virginia Tech

  • White Papers // Apr 2010

    Knowing Where Your Input Is From: Kernel-Level Data-Provenance Verification

    This paper describes a cryptographic provenance verification approach for ensuring system properties and system-data integrity at kernel-level. Its two concrete applications are demonstrated in malware traffic detection and keystroke-based bot identification. Specifically, the authors first demonstrate the provenance verification approach by realizing a lightweight framework for blocking outbound malware traffic....

    Provided By Virginia Tech

  • White Papers // Jul 2009

    Accelerator-Oriented Algorithm Transformation for Temporal Data Mining

    Temporal data mining algorithms are becoming increasingly important in many application domains including computational neuroscience, especially the analysis of spike train data. While application scientists have been able to readily gather multi-neuronal datasets, analysis capabilities have lagged behind, due to both lack of the powerful algorithms and inaccessibility to powerful...

    Provided By Virginia Tech

  • White Papers // Jan 2011

    Compositional Specification and Realization of Mixed-Initiative Web Dialogs

    The authors present DialogXML a markup language approach to specifying and realizing mixed-initiative web dialogs on mobile devices. By capturing the functional structure of the dialog independent of the modalities used to realize it, DialogXML facilitates the implementation of web interfaces that integrate hyperlink and speech modes of interaction. It...

    Provided By Virginia Tech

  • White Papers // Sep 2009

    Discovering Excitatory Networks From Discrete Event Streams With Applications to Neuronal Spike Train Analysis

    Mining temporal network models from discrete event streams is an important problem with applications in computational neuroscience, physical plant diagnostics, and human-computer interaction modeling. The authors focus in this paper on temporal models representable as excitatory networks where all connections are stimulative, rather than inhibitive. Through this emphasis on excitatory...

    Provided By Virginia Tech

  • White Papers // Dec 2008

    Optimizing Performance, Cost, and Sensitivity in Pairwise Sequence Search on a Cluster of PlayStations

    The Smith-Waterman algorithm is a dynamic programming method for determining optimal local alignments between nucleotide or protein sequences. However, it suffers from quadratic time and space complexity. As a result, many algorithmic and architectural enhancements have been proposed to solve this problem, but at the cost of reduced sensitivity in...

    Provided By Virginia Tech

  • White Papers // Dec 2010

    Maintainable and Reusable Scientific Software Adaptation

    Scienti c software must be adapted for different execution environments, problem sets, and available resources to ensure its efficiency and reliability. Although adaptation patterns can be found in a sizable percentage of recent scientific applications, the traditional scientific software stack lacks the adequate adaptation abstractions and tools. As a result,...

    Provided By Virginia Tech

  • White Papers // Sep 2008

    Overcoming JVM HotSwap Constraints Via Binary Rewriting

    Java HotSpot VM provides a facility for replacing classes at runtime called HotSwap. One design property of HotSwap is that the signature of a replaced class must remain the same between different versions, which significantly constrains the programmer modifying a class to be replaced. Specifically, the programmer is precluded from...

    Provided By Virginia Tech

  • White Papers // May 2009

    Enhancing Source-Level Programming Tools With an Awareness of Transparent Program Transformations

    Programs written in managed languages are compiled to a platform-independent intermediate representation, such as Java byte code. The relative high level of Java byte code has engendered a widespread practice of changing the byte code directly, without modifying the maintained version of the source code. This practice, called byte code...

    Provided By Virginia Tech

  • White Papers // Apr 2009

    Remote Batch Invocation for Compositional Object Services

    Because Remote Procedure Calls do not compose efficiently, designers of distributed object systems use Data Transfer and Remote Facade patterns to create large-granularity interfaces, hard-coded for particular client use cases. As an alternative to RPC-based distributed objects, this paper presents Remote Batch Invocation (RBI), language support for explicit client-defined batches....

    Provided By Virginia Tech

  • White Papers // Feb 2009

    Explicit Batching for Distributed Objects

    Although distributed object systems, for example RMI and CORBA, enable object-oriented programs to be easily distributed across a network, achieving acceptable performance usually requires client-specific optimization of server interfaces, making such systems difficult to maintain and evolve. Automatic optimization techniques, including Batched Futures and Communication Restructuring, do not work as...

    Provided By Virginia Tech

  • White Papers // Feb 2009

    Flexible and Efficient In-Vivo Enhancement for Grid Applications

    In a grid application, some requirements may change while the execution is in progress. This paper presents in vivo enhancement - updating running grid applications to facilitate their perfective maintenance. Because applications in this domain are not only typically long-running, but also time-consuming to deploy, the authors propose a dynamic...

    Provided By Virginia Tech

  • White Papers // Feb 2010

    Understanding the Tenets of Agile Software Engineering: Lecturing, Exploration and Critical Thinking

    The use of agile principles and practices in software development is becoming a powerful force in today's workplace. In the authors' quest to develop better products, therefore, it is imperative that they strive to learn and understand the application of Agile methods, principles and techniques to the software development enterprise....

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