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Articles 1 - 19 of 19
Full-Text Articles in Physical Sciences and Mathematics
Feedback Thermal Control Of Real-Time Systems On Multicore Processors, Yong Fu, Nicholas Kottenstette, Chenyang Lu, Xenofon D. Koutsoukos
Feedback Thermal Control Of Real-Time Systems On Multicore Processors, Yong Fu, Nicholas Kottenstette, Chenyang Lu, Xenofon D. Koutsoukos
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Real-time systems face significant challenges in thermal management with their adoption of modern multicore processors. While earlier research on feedback thermal control has shown promise in dealing with the uncertainties in the thermal characteristics, multicore processors introduce new challenges that cannot be handled by previous solutions designed for single-core processors. Multicore processors require the temperatures and real-time performance of multiple cores to be controlled simultaneously, leading to multi-input-multi-output (MIMO) control problems with inter-core thermal coupling. Furthermore, current Dynamic Voltage and Frequency Scaling (DVFS) mechanisms only support a finite set of states, leading to discrete control variables that cannot be handled …
Webcam Image Alignment, Matthew Klein
Webcam Image Alignment, Matthew Klein
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No abstract provided.
Efficient Deadlock Avoidance For Streaming Computation With Filtering, Jeremy Buhler, Kunal Agrawal, Peng Li, Roger D. Chamberlain
Efficient Deadlock Avoidance For Streaming Computation With Filtering, Jeremy Buhler, Kunal Agrawal, Peng Li, Roger D. Chamberlain
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In this report, we show that deadlock avoidance for streaming computations with filtering can be performed efficiently for a large class of DAG topologies. We first give efficient algorithms for dummy interval computation in series-parallel DAGs, then generalize our results to a larger graph family, the CS4DAGs, in which every undirected cycle has exactly one source and one sink. Our results show that, for a large set of application topologies that are both intuitively useful and formalizable, the streaming model with filtering can be implemented safely with reasonable compilation overhead.
Implementation And Evaluation Of Mixed-Criticality Scheduling Approaches For Periodic Tasks, Huang-Ming Huang, Christopher Gill, Chenyang Lu
Implementation And Evaluation Of Mixed-Criticality Scheduling Approaches For Periodic Tasks, Huang-Ming Huang, Christopher Gill, Chenyang Lu
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Traditional fixed-priority scheduling analysis for periodic task sets is based on the assumption that all tasks are equally critical to the correct operation of the system. Therefore, every task has to be schedulable under the scheduling policy, and estimates of tasks’ worst case execution times must be conservative in case a task runs longer than is usual. To address the significant under-utilization of a system’s resources under normal operating conditions that can arise from these assumptions, three main approaches have been proposed: priority assignment, period transformation, and zero-slack scheduling. However, to date there has been no quantitative comparison of system …
Multi-Core Real-Time Scheduling For Generalized Parallel Task Models, Abusayeed Saifullah, Kunal Agrawal, Chenyang Lu, Christopher Gill
Multi-Core Real-Time Scheduling For Generalized Parallel Task Models, Abusayeed Saifullah, Kunal Agrawal, Chenyang Lu, Christopher Gill
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Multi-core processors over a significant performance increase over single-core processors. Therefore, they have the potential to enable computation-intensive real-time applications with stringent timing constraints that cannot be met on traditional single-core processors. However, most results in traditional multiprocessor real-time scheduling are limited to sequential programming models and ignore intra-task parallelism. In this paper, we address the problem of scheduling periodic parallel tasks with implicit deadlines on multi-core processors. We first consider a synchronous task model where each task consists of segments, each segment having an arbitrary number of parallel threads that synchronize at the end of the segment. We propose …
Flux Balance Analysis Of Dynamic Metabolism In Shewanella Oneidensis Mr-1 Using A Static Optimization Approach, Xueyang Feng, You Xu, Yixin Chen, Yinjie Tang
Flux Balance Analysis Of Dynamic Metabolism In Shewanella Oneidensis Mr-1 Using A Static Optimization Approach, Xueyang Feng, You Xu, Yixin Chen, Yinjie Tang
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Shewanella bacteria are facultative anaerobes isolated from aquatic and sedimentary environments (Hau and Gralnick 2007) with a broad capacity for reduction of multiple electron receptors (Pinchuk et al. 2009; Serres and Riley 2006), including Fe(III), Mn(IV), sulfur, nitrate, and fumarate. With the accomplishment of complete genome sequencing of several Shewanella bacteria, the general pictures of the carbon metabolism have been revealed (Serres and Riley 2006). metabolism. One of the most physiological methods to decipher the time-variant metabolic regulation is to determine the dynamic distribution of intracellular metabolic fluxes since it reveals the final response of cellular metabolism to genomic, transcriptional …
End-To-End Communication Delay Analysis In Wirelesshart Networks, Abusayeed Saifullah, You Xu, Chenyang Lu, Yixin Chen
End-To-End Communication Delay Analysis In Wirelesshart Networks, Abusayeed Saifullah, You Xu, Chenyang Lu, Yixin Chen
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WirelessHART is a new standard specifically designed for real-time and reliable communication between sensor and actuator devices for industrial process monitoring and control applications. End-to-end communication delay analysis for WirelessHART networks is required to determine the schedulability of real-time data flows from sensors to actuators for the purpose of acceptance test or workload adjustment in response to network dynamics. In this paper, we map the scheduling of real-time periodic data flows in a WirelessHART network to real-time multiprocessor scheduling. We then exploit the response time analysis for multiprocessor scheduling and propose a novel method for the delay analysis that establishes …
Real Time Baseball Augmented Reality, Adam Kraft
Real Time Baseball Augmented Reality, Adam Kraft
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As computer hardware becomes increasingly powerful, there is an ongoing trend towards integrating complex, legacy real-time systems using fewer hosts through virtualization. Especially in embedded systems domains such as avionics and automotive engineerin
Hierarchical Scheduling For Multicores With Multilevel Cache Hierarchies, Kunal Agrawal, Jim Sukha
Hierarchical Scheduling For Multicores With Multilevel Cache Hierarchies, Kunal Agrawal, Jim Sukha
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Cache-locality is an important consideration for the performance in multicore systems. In modern and future multicore systems with multilevel cache hierarchies, caches may be arranged in a tree of caches, where a level k cache is shared between Pk processors, called a processor group, and Pk increases with k. In order to get good performance, as much as possible, subcomputations that share more data should execute on processors which share a lower-level cache. Therefore, the number of cache misses in these systems depends on the scheduling decisions, and a scheduler is responsible for not just achieving good load-balance and low …
Generating Muscle Driven Arm Movements Using Reinforcement Learning, Alex S. Broad
Generating Muscle Driven Arm Movements Using Reinforcement Learning, Alex S. Broad
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This project focuses on using Reinforcement Learning to optimize arm dynamics through muscle control for desired trajectories. The goal of this project was to create a tool that can be used to gain a better understanding of the arm’s muscles and collect information that is useful in many other disciplines such as biomechanics, anthropology, medicine and robotics. I developed biologically realistic models of primate arm's using Stanford’s SimTK software, an open-source tool for modeling musculoskeletal structures. I then made use of Differential Dynamic Programming in order to generate novel movements from first principles and optimize motion over a specified trajectory. …
The Forest Overlay Network, Logan Stafman
The Forest Overlay Network, Logan Stafman
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Forest is an overlay network designed for large real-time distributed systems. In particular, we’re interested in virtual worlds that provide high-quality interaction over a constantly changing pattern of communication. Forest is suitable for applications in which many entities send data to a large set of constantly changing entities. By using tree-structured channels, we can create logically isolated private networks which support both unicast and multicast routing. In this paper, we will discuss the core components of Forest and measure the performance of the control elements of the network. We will also provide examples of control sequences and the roles played …
Results Of An Observational Study On Sketching, Cindy Grimm
Results Of An Observational Study On Sketching, Cindy Grimm
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We present the results of an observational study on sketching. Artists were asked to sketch a small number of objects and comment on how and why they made the marks they did. We summarize these findings, from low-level details on individual marks through the drawing construction order. Based on these observations we provide suggestions for future research directions in 3D sketching.
A Survey On Communication Networks In Emergency Warning Systems, Yan Li
A Survey On Communication Networks In Emergency Warning Systems, Yan Li
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No abstract provided.
Mercury Blastn Biosequence Similarity Search System: Technical Reference Guide, Jeremy Buhler
Mercury Blastn Biosequence Similarity Search System: Technical Reference Guide, Jeremy Buhler
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This guide documents the operation of the Mercury BLASTN system for hardware-accelerated DNA similarity search. It includes detailed information on the syntax and limitations of the system's component commands, as well as a description of the system's hardware platform suitable for administrators who need to maintain a Mercury BLASTN system. Mercury BLASTN is a product of the High Performance COmputational Biology Group at Washington University.
Distributed Channel Allocation Algorithms For Wireless Sensor Networks, Abusayeed Saifullah, You Xu, Chenyang Lu, Yixin Chen
Distributed Channel Allocation Algorithms For Wireless Sensor Networks, Abusayeed Saifullah, You Xu, Chenyang Lu, Yixin Chen
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Interference between concurrent transmissions can cause severe performance degradation in wireless sensor networks (WSNs). While multiple channels available in WSN technology such as IEEE 802.15.4 can be exploited to mitigate interference, channel allocation can have a significant impact on the performance of multi-channel communication. This paper proposes a set of distributed algorithms for near-optimal channel allocation in WSNs with theoretical bounds. We first consider the problem of minimizing the number of channels needed to remove interference in a WSN, and propose both receiver-based and link-based distributed channel allocation protocols. For WSNs with an insufficient number of channels, we formulate a …
2-Edge-Connectivity And 2-Vertex-Connectivity With Fault Containment, Abusayeed Saifullah
2-Edge-Connectivity And 2-Vertex-Connectivity With Fault Containment, Abusayeed Saifullah
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Self-stabilization for non-masking fault-tolerant distributed system has received considerable research interest over the last decade. In this paper, we propose a self-stabilizing algorithm for 2-edge-connectivity and 2-vertex-connectivity of an asynchronous distributed computer network. It is based on a self-stabilizing depth-first search, and is not a composite algorithm in the sense that it is not composed of a number of self-stabilizing algorithms that run concurrently. The time and space complexities of the algorithm are the same as those of the underlying self-stabilizing depth-first search algorithm.
Optimization Of Gene Prediction Via More Accurate Phylogenetic Substitution Models, Ezekiel Maier, Randall H. Brown, Michael R. Brent
Optimization Of Gene Prediction Via More Accurate Phylogenetic Substitution Models, Ezekiel Maier, Randall H. Brown, Michael R. Brent
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Determining the beginning and end positions of each exon in each protein coding gene within a genome can be difficult because the DNA patterns that signal a gene’s presence have multiple weakly related alternate forms and the DNA fragments that comprise a gene are generally small in comparison to the size of the genome. In response to this challenge, automated gene predictors were created to generate putative gene structures. N SCAN identifies gene structures in a target DNA sequence and can use conservation patterns learned from alignments between a target and one or more informant DNA sequences. N SCAN uses …
Energy-Efficient Low Power Listening For Wireless Sensor Networks In Noisy Environments, Mo Sha, Gregory Hackmann, Chenyang Lu
Energy-Efficient Low Power Listening For Wireless Sensor Networks In Noisy Environments, Mo Sha, Gregory Hackmann, Chenyang Lu
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Low Power Listening (LPL) is a common MAC-layer technique for reducing energy consumption in wireless sensor networks, where nodes periodically wake up to sample the wireless channel to detect activity. However, LPL is highly susceptible to false wakeups caused by environmental noise being detected as activity on the channel, causing nodes to spuriously wake up in order to receive nonexistent transmissions. In empirical studies in residential environments, we observe that the false wakeup problem can significantly increase a node's duty cycle, compromising the benefit of LPL. We also find that the energy-level threshold used by the Clear Channel Assessment (CCA) …
Near Optimal Rate Selection For Wireless Control Systems, Abusayeed Saifullah, Chengjie Wu, Paras Babu Tiwari, You Xu, Yong Fu, Chenyang Lu, Yixin Chen
Near Optimal Rate Selection For Wireless Control Systems, Abusayeed Saifullah, Chengjie Wu, Paras Babu Tiwari, You Xu, Yong Fu, Chenyang Lu, Yixin Chen
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With the advent of industrial standards such as WirelessHART, process industries are now gravitating towards wireless control systems. Due to limited bandwidth in a wireless network shared by multiple control loops, it is critical to optimize the overall control performance. In this paper, we address the scheduling-control co-design problem of determining the optimal sampling rates of feedback control loops sharing a WirelessHART network. The objective is to minimize the overall control cost while ensuring that all data flows meet their end-to-end deadlines. The resulting constrained optimization based on existing delay bounds for WirelessHART networks is challenging since it is non-differentiable, …