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Articles 151 - 180 of 683
Full-Text Articles in Computer Engineering
Reliable Data Collection From Mobile Users For Real-Time Clinical Monitoring, Octav Chipara, Christopher Brooks, Sangeeta Bhattacharya, Chenyang Lu
Reliable Data Collection From Mobile Users For Real-Time Clinical Monitoring, Octav Chipara, Christopher Brooks, Sangeeta Bhattacharya, Chenyang Lu
All Computer Science and Engineering Research
Real-time patient monitoring is critical to early detection of clinical patient deterioration in general hospital wards. A key challenge in such applications is to reliably deliver sensor data from mobile patients. We present an empirical analysis on the reliability of data collection from wireless pulse oximeters attached to users. We observe that most packet loss occur from mobile users to their first-hop relays. Based on this insight we developed the Dynamic Relay Association Protocol (DRAP), a simple and effective mechanism for dynamically discovering the right relays for wireless sensors attached to mobile users. DRAP enables highly reliable data collection from …
Real-Time Performance And Middleware On Multicore Linux Platforms, Yuanfang Zhang, Christopher Gill, Chenyang Lu
Real-Time Performance And Middleware On Multicore Linux Platforms, Yuanfang Zhang, Christopher Gill, Chenyang Lu
All Computer Science and Engineering Research
An increasing number of distributed real-time applications are running on multicore platforms. However, existing real-time middleware (e.g., Real-Time CORBA) lacks support for scheduling soft real-time tasks on multicore platforms while guaranteeing their time constraints will be satisfied. This paper makes three contributions to the state of the art in real-time system software for multicore platforms. First, it offers what is to our knowledge the first experimental analysis of real-time performance for vanilla Linux primitives on multicore platforms. Second, it presents MC-ORB, the first real-time object request broker (ORB), designed to exploit the features of multicore platforms, with admission control and …
Verification Of Component-Based Distributed Real-Time Systems, Huang-Ming Huang, Christopher Gill
Verification Of Component-Based Distributed Real-Time Systems, Huang-Ming Huang, Christopher Gill
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Component-based software architectures enable reuse by separating application-specific concerns into modular components that are shielded from each other and from common concerns addressed by underlying services. Even so, concerns such as invocation rates, execution latencies, deadlines, and concurrency and scheduling semantics still cross-cut component boundaries in many real-time systems. Verification of these systems therefore must consider how composition of components relates to timing, resource utilization, and other properties. However, existing approaches only address a sub-set of the concerns that must be modeled in component-based distributed real-time systems, and a new more comprehensive approach is thus needed. To address that need, …
Animal Microrna Target Prediction By Incorporating Diverse Sequence-Specific Determinants, Yun Zheng, Weixiong Zhang
Animal Microrna Target Prediction By Incorporating Diverse Sequence-Specific Determinants, Yun Zheng, Weixiong Zhang
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More recent evidence has shown that access of animal microRNAs (miRNAs) to their complementary sites in target mRNAs is determined by more sequence-specific determinants than the seed regions in the 5' end of miRNAs. Although these factors have been shown to be related to the repressive power of miRNAs and used, in separate programs, to predict the efficacy of miRNA complementary sites, it remains unclear whether these factors can help to improve miRNA target prediction. We develop a new miRNA target prediction algorithm, called Hitsensor, by incorporating more sequence-specific features that determine complementarities between miRNAs and their targets, in addition …
Multi-Application Deployment In Integrated Sensing Systems Based On Quality Of Monitoring, Sangeeta Bhattacharya, Abusayeed Saifullah, Chenyang Lu, Gruia-Catalin Roman
Multi-Application Deployment In Integrated Sensing Systems Based On Quality Of Monitoring, Sangeeta Bhattacharya, Abusayeed Saifullah, Chenyang Lu, Gruia-Catalin Roman
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No abstract provided.
Transcriptome Analysis Of Alzheimer's Disease Identifies Links To Cardiovascular Disease, Monika Ray, Jianhua Ruan, Weixiong Zhang
Transcriptome Analysis Of Alzheimer's Disease Identifies Links To Cardiovascular Disease, Monika Ray, Jianhua Ruan, Weixiong Zhang
All Computer Science and Engineering Research
No abstract provided.
Reconfigurable Real-Time Middleware For Distributed Cyber-Physical Systems With Aperiodic Events, Yuanfang Zhang, Christopher Gill, Chenyang Lu
Reconfigurable Real-Time Middleware For Distributed Cyber-Physical Systems With Aperiodic Events, Yuanfang Zhang, Christopher Gill, Chenyang Lu
All Computer Science and Engineering Research
Different distributed cyber-physical systems must handle aperiodic and periodic events with diverse requirements. While existing real-time middleware such as Real-Time CORBA has shown promise as a platform for distributed systems with time constraints, it lacks flexible configuration mechanisms needed to manage end-to-end timing easily for a wide range of different cyber-physical systems with both aperiodic and periodic events. 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 event handling in distributed cyber-physical systems. Empirical results demonstrate the need for, …
Software And Hardware Acceleration Of The Genomic Motif Finding Tool Phylonet, Justin Brown
Software And Hardware Acceleration Of The Genomic Motif Finding Tool Phylonet, Justin Brown
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No abstract provided.
Deciding Joinability Modulo Ground Equations In Operational Type Theory, Adam Petcher, Aaron Stump
Deciding Joinability Modulo Ground Equations In Operational Type Theory, Adam Petcher, Aaron Stump
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Operational Type Theory (OpTT) can be used to construct and check proofs related to programs, but the development of these proofs can be somewhat tedious. An algorithm is presented that can be used to automatically generate proofs of equality in OpTT. The algorithm takes as input a set of ground equations and two terms that should be tested for joinability modulo the supplied ground equations. The algorithm will equate the terms if and only if there exists an OpTT proof that can equate the two terms using only the proof rules related to evaluation under the operational semantics, symmetry, transitivity, …
A Holistic Approach To Decentralized Structural Damage Localization Using Wireless Sensor Networks, Gregory Hackmann, Fei Sun, Nestor Castaneda, Chenyang Lu, Shirley Dyke
A Holistic Approach To Decentralized Structural Damage Localization Using Wireless Sensor Networks, Gregory Hackmann, Fei Sun, Nestor Castaneda, Chenyang Lu, Shirley Dyke
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Wireless sensor networks (WSNs) have become an increasingly compelling platform for Structural Health Monitoring (SHM) applications, since they can be installed relatively inexpensively onto existing infrastructure. Existing approaches to SHM in WSNs typically address computing system issues or structural engineering techniques, but not both in conjunction. In this paper, we propose a holistic approach to SHM that integrates a decentralized computing architecture with the Damage Localization Assurance Criterion algorithm. In contrast to centralized approaches that require transporting large amounts of sensor data to a base station, our system pushes the execution of portions of the damage localization algorithm onto the …
Flexible Service Provisioning For Heterogeneous Sensor Networks, Chien-Liang Fok, Gruia-Catalin Roman, Chenyang Lu
Flexible Service Provisioning For Heterogeneous Sensor Networks, Chien-Liang Fok, Gruia-Catalin Roman, Chenyang Lu
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This paper presents Servilla, a highly flexible service provisioning framework for heterogeneous wireless sensor networks. Its service-oriented programming model and middleware enable developers to construct platform-independent applications over a dynamic set of devices with diverse computational resources and sensors. A salient feature of Servilla is its support for dynamic discovery and binding to local and remote services, which enables flexible and energy-efficient in-network collaboration among heterogeneous devices. Furthermore, Servilla provides a modular middleware architecture that can be easily tailored for devices with a wide range of resources, allowing even resource-limited devices to provide services and leverage resource-rich devices for in-network …
Scheduling Design And Verification For Open Soft Real-Time Systems, Robert Glaubius, Terry Tidwell, William D. Smart, Christopher Gill
Scheduling Design And Verification For Open Soft Real-Time Systems, Robert Glaubius, Terry Tidwell, William D. Smart, Christopher Gill
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Open soft real-time systems, such as mobile robots, experience unpredictable interactions with their environments and yet must respond both adaptively and with reasonable temporal predictability. New scheduling approaches are needed to address the demands of such systems, in which many of the assumptions made by traditional real-time scheduling theory do not hold. In previous work we established foundations for a scheduling policy design and verification approach for open soft real-time systems, that can use different decision models, e.g., a Markov Decision Process (MDP), to capture the nuances of their scheduling semantics. However, several important refinements to the preliminary techniques developed …
Faster Optimal State-Space Search With Graph Decomposition And Reduced Expansion, Yixin Chen
Faster Optimal State-Space Search With Graph Decomposition And Reduced Expansion, Yixin Chen
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Traditional AI search methods, such as BFS, DFS, and A*, look for a path from a starting state to the goal in a state space most typically modelled as a directed graph. Prohibitively large sizes of the state space graphs make optimal search difficult. A key observation, as manifested by the SAS+ formalism for planning, is that most commonly a state-space graph is well structured as the Cartesian product of several small subgraphs. This paper proposes novel search algorithms that exploit such structure. The results reveal that standard search algorithms may explore many redundant paths. Our algorithms provide an automatic …
Exploration Of Dynamic Memory, Delvin Curvin Defoe
Exploration Of Dynamic Memory, Delvin Curvin Defoe
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Since the advent of the Java programming language and the development of real-time garbage collection, Java has become an option for implementing real-time applications. The memory management choices provided by real-time garbage collection allow for real-time eJava developers to spend more of their time implementing real-time solutions. Unfortunately, the real-time community is not convinced that real-time garbage collection works in managing memory for Java applications deployed in a real-time context. Consequently, the Real-Time for Java Expert Group formulated the Real-Time Specification for Java (RTSJ) standards to make Java a real-time programming language. In lieu of garbage collection, the RTSJ proposed …
Comparing Features Of Three-Dimensional Object Models Using Registration Based On Surface Curvature Signatures, Timothy David Gatzke, Cindy M. Grimm
Comparing Features Of Three-Dimensional Object Models Using Registration Based On Surface Curvature Signatures, Timothy David Gatzke, Cindy M. Grimm
All Computer Science and Engineering Research
This dissertation presents a technique for comparing local shape properties for similar three-dimensional objects represented by meshes. Our novel shape representation, the curvature map, describes shape as a function of surface curvature in the region around a point. A multi-pass approach is applied to the curvature map to detect features at different scales. The feature detection step does not require user input or parameter tuning. We use features ordered by strength, the similarity of pairs of features, and pruning based on geometric consistency to efficiently determine key corresponding locations on the objects. For genus zero objects, the corresponding locations are …
Unwoven Aspect Analysis, Morgan G. Deters
Unwoven Aspect Analysis, Morgan G. Deters
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Various languages and tools supporting advanced separation of concerns (such as aspect-oriented programming) provide a software developer with the ability to separate functional and non-functional programmatic intentions. Once these separate pieces of the software have been specified, the tools automatically handle interaction points between separate modules, relieving the developer of this chore and permitting more understandable, maintainable code. Many approaches have left traditional compiler analysis and optimization until after the composition has been performed; unfortunately, analyses performed after composition cannot make use of the logical separation present in the original program. Further, for modular systems that can be configured with …
Performance Evaluation For Hybrid Architectures, Praveen Krishnamurthy
Performance Evaluation For Hybrid Architectures, Praveen Krishnamurthy
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In this dissertation we discuss methologies for estimating the performance of applications on hybrid architectures, systems that include various types of computing resources (e.g. traditional general-purpose processors, chip multiprocessors, reconfigurable hardware). A common use of hybrid architectures will be to deploy coarse pipeline stages of application on "suitable" compute units with communication path for transferring data. The first problem we focus on relates to the sizing the data queues between the different processing elements of an hybrid system. Much of the discussion centers on our analytical models that can be used to derive performance metrics of interest such as, throughput …
Mercury Blast Dictionaries: Analysis And Performance Measurement, Jeremy Buhler
Mercury Blast Dictionaries: Analysis And Performance Measurement, Jeremy Buhler
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This report describes a hashing scheme for a dictionary of short bit strings. The scheme, which we call near-perfect hashing, was designed as part of the construction of Mercury BLAST, an FPGA-based accelerator for the BLAST family of biosequence comparison algorithms. Near-perfect hashing is a heuristic variant of the well-known displacement hashing approach to building perfect hash functions. It uses a family of hash functions composed from linear transformations on bit vectors and lookups in small precomputed tables, both of which are especially appropriate for implementation in ardware logic. We show empirically that for inputs derived from genomic DNA sequences, …
Network Access In A Diversified Internet, M. Wilson, F. Kuhns, J. Turner
Network Access In A Diversified Internet, M. Wilson, F. Kuhns, J. Turner
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There is a growing interest in virtualized network infrastructures as a means to enable experimental evaluation of new network architectures on a realistic scale. The National Science Foundation's GENI initiative seeks to develop a national experimental facility that would include virtualized network platforms that can support many concurrent experimental networks. Some researchers seek to make virtualization a central architectural component of a future Internet, so that new network architectures can be introduced at any time, without the barriers to entry that currently make this difficult. This paper focuses on how to extend the concept of virtualized networking through LAN-based access …
Extending Bpel For Interoperable Pervasive Computing, Gregory Hackmann, Christopher Gill, Christopher Gill, Gruia-Catalin Roman
Extending Bpel For Interoperable Pervasive Computing, Gregory Hackmann, Christopher Gill, Christopher Gill, Gruia-Catalin Roman
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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 …
Optimal Discrete Rate Adaptation For Distributed Real-Time Systems With End-To-End Tasks, Yingming Chen, Chenyang Lu, Xenofon Koutsoukos
Optimal Discrete Rate Adaptation For Distributed Real-Time Systems With End-To-End Tasks, Yingming Chen, Chenyang Lu, Xenofon Koutsoukos
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Many distributed real-time systems face the challenge of dynamically maximizing system utility in response to fluctuations in system workload. We present the MultiParametric Rate Adaptation (MPRA) algorithm for discrete rate adaptation in distributed real-time systems with end-to-end tasks. The key novelty and advantage of MPRA is that it can efficiently produce optimal solutions in response to workload changes such as dynamic task arrivals. Through oline preprocessing MPRA transforms a NP-hard utility optimization problem to a set of simple linear functions in different regions expressed in term of CPU utilization changes caused by workload variations. At run time MPRA produces optimal …
Configurable Component Middleware For Distributed Real-Time Systems With Aperiodic And Periodic Tasks, Yuanfang Zhang, Christopher Gill, Chenyang Lu
Configurable Component Middleware For Distributed Real-Time Systems With Aperiodic And Periodic Tasks, Yuanfang Zhang, Christopher Gill, Chenyang Lu
All Computer Science and Engineering Research
Many distributed real-time applications must handle mixed periodic and aperiodic 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 periodic and aperiodic 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 effectiveness of our configurable component middleware approach in supporting different applications with periodic and aperiodic tasks.
Fair Efficiency, Or Low Average Delay Without Starvation, Christoph Jechlitschek, Sergey Gorinsky
Fair Efficiency, Or Low Average Delay Without Starvation, Christoph Jechlitschek, Sergey Gorinsky
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Elastic applications are primarily interested in minimal delay achievable for their messages under current network load. In this paper, we investigate how to transmit such messages over a bottleneck link efficiently and fairly. While SRPT (Shortest Remaining Processing Time) is an optimally efficient algorithm that minimizes average delay of messages, large messages might starve under SRPT in heavy load conditions. PS (Processor Sharing) and ViFi (Virtual Finish Time First) are fair but yield higher average delays than under SRPT. We explore the class of fair algorithms further and prove that no online algorithm in this class is optimally efficient. Then, …
Scheduling Induced Bounds And The Verification Of Preemptive Real-Time Systems, Terry Tidwell, Christopher Gill, Venkita Subramonian
Scheduling Induced Bounds And The Verification Of Preemptive Real-Time Systems, Terry Tidwell, Christopher Gill, Venkita Subramonian
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Distributed real-time and embedded (DRE) systems have stringent constraints on timeliness and other properties whose assurance is crucial to correct system behavior. Our previous research has shown that detailed models of essential middleware mechanisms can be developed, composed, and for constrained examples verified tractably, using state of the art timed automata model checkers. However, to apply model checking to a wider range of real-time systems, particularly those involving more general forms of preemptive concurrency, new techniques are needed to address decidability and tractability concerns. This paper makes three contributions to research on formal verification and validation of DRE systems. First, …
Emergent Task Allocation For Mobile Robots Through Intentions And Directives, Nuzhet Atay, Burchan Bayazit
Emergent Task Allocation For Mobile Robots Through Intentions And Directives, Nuzhet Atay, Burchan Bayazit
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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 …
Perpetual: Byzantine Fault Tolerance For Federated Distributed Applications, Sajeeva L. Pallemulle, Haraldur D. Thorvaldsson, Kenneth J. Goldman
Perpetual: Byzantine Fault Tolerance For Federated Distributed Applications, Sajeeva L. Pallemulle, Haraldur D. Thorvaldsson, Kenneth J. Goldman
All Computer Science and Engineering Research
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 …
Expression Profiling Of Human Donor Lungs To Understand Primary Graft Dysfunction After Lung Transplantation, Monika Ray, Sekhar Dharmarajan, Johannes Freudenberg, Weixiong Zhang, Alexander G. Patterson
Expression Profiling Of Human Donor Lungs To Understand Primary Graft Dysfunction After Lung Transplantation, Monika Ray, Sekhar Dharmarajan, Johannes Freudenberg, Weixiong Zhang, Alexander G. Patterson
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Lung transplantation is the treatment of choice for end-stage pulmonary diseases. A limited donor supply has resulted in 4000 patients on the waiting list. Currently, 10-20% of donor organs offered for transplantation are deemed suitable under the selection criteria, of which 15-25% fails due to primary graft dysfunction (PGD). This has resulted in increased efforts to search for alternative donor lungs selection criteria. In this study, we attempt to further our understanding of PGD by observing the changes in gene expression across donor lungs that developed PGD versus those that did not. Our second goal is to use a machine …
Improving Individual Flow Performance With Multiple Queue Fair Queuing, Manfred Georg, Christopher Jechlitschek, Sergey Gorinsky
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 …
Splice: A Standardized Peripheral Logic And Interface Creation Engine, Justin Thiel
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 …
Byzantine Fault-Tolerant Web Services For N-Tier And Service Oriented Architectures, Sajeeva L. Pallemulle, Kenneth J. Goldman
Byzantine Fault-Tolerant Web Services For N-Tier And Service Oriented Architectures, Sajeeva L. Pallemulle, Kenneth J. Goldman
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Web Services that provide mission-critical functionality must be replicated to guarantee correct execution and high availability in spite of arbitrary (Byzantine) faults. Existing approaches for Byzantine fault-tolerant execution of Web Services are inadequate to guarantee correct execution due to several major limitations. Some approaches do not support interoperability between replicated Web Services. Other approaches do not provide fault isolation guarantees that are strong enough to prevent cascading failures across organizational and application boundaries. Moreover, existing approaches place impractical limitations on application development by not supporting long-running active threads of computation, fully asynchronous communication, and access to host specific information. We …