Since multicore processors are now the architectural standard and parallel computing is in the core CS curriculum, CS educators must create pedagogical materials and tools to help their students master parallel abstra...
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Since multicore processors are now the architectural standard and parallel computing is in the core CS curriculum, CS educators must create pedagogical materials and tools to help their students master parallel abstractions and concepts. This paper describes the thread safe graphics library (TSGL), a tool by which an educator can add graphics calls to a working multithreaded program in order to make visible the underlying parallel behavior. Using TSGL, an instructor (or student) can create parallel visualizations that clearly show the parallel patterns or techniques a given program is using, allowing students to see the parallel behavior in near real-time as the program is running. TSGL includes many examples that illustrate its use;this paper presents a representative sample, that can be used either in a lecture or a self-paced lab format. We also present evidence that such visualizations improve student understanding of abstract parallel concepts. (C) 2018 Elsevier Inc. All rights reserved.
The Finite Pointset Method (FPM) is a meshfree method for simulations in the field of fluid dynamics and continuum mechanics (Tiwari and Kuhnert, Finite pointset method based on the projection method for simulations o...
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ISBN:
(纸本)9783030151195;9783030151188
The Finite Pointset Method (FPM) is a meshfree method for simulations in the field of fluid dynamics and continuum mechanics (Tiwari and Kuhnert, Finite pointset method based on the projection method for simulations of the incompressible Navier-Stokes equations. Springer, Berlin, 2003). The key idea in FPM is to discretize the necessary differential operators by using stencils generated by a least squares approach on a pointcloud that is moving in every time step. Applying Algebraic Multigrid Methods (AMG) to the linear systems arising in FPM comes with various challenges, see our previous work Metsch et al. (Comput Vis Sci, reviewed) and Nick et al. (Linear solvers for the finite pointset method. In: Schafer, M., Behr, M., Mehl, M., Wohlmuth, B. (eds.) Recent advances in computational engineering. Springer, Cham, 2018). In Nick et al. (Linear solvers for the finite pointset method. In: Schafer, M., Behr, M., Mehl, M., Wohlmuth, B. (eds.) Recent advances in computational engineering. Springer, Cham, 2018) we limited ourselves to essentially irreducible matrices, saying that if a matrix arising from FPM is not essentially irreducible, we can employ a parallel algorithm in order to detect those subsystems that are essentially irreducible. This paper introduces the algorithm that we use in order to detect independent parts of the FPM pointcloud, which we call components. The algorithm that we propose has a theoretical complexity of O(vertical bar V vertical bar) in the average case, where vertical bar V vertical bar is the number of points in the pointcloud. Our experiments with a real world model however show that in practice the complexity is much better. The experiments also show that in order to guarantee a stable convergence of the arising linear systems, detecting components is essential, as singular components can occur in certain situations.
Industrial embedded systems are cost sensitive, and hardware cost of industrial production should be reduced for high profit. The functional safety requirement must be satisfied according to industrial functional safe...
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Industrial embedded systems are cost sensitive, and hardware cost of industrial production should be reduced for high profit. The functional safety requirement must be satisfied according to industrial functional safety standards. This study proposes three hardware cost optimization algorithms for functional safety-critical parallel applications on heterogeneous distributed embedded systems during the design phase. The explorative hardware cost optimization (EHCO), enhanced EHCO (EEHCO), and simplified EEHCO (SEEHCO) algorithms are proposed step by step. Experimental results reveal that EEHCO can obtain minimum hardware cost, whereas SEEHCO is efficient for large-scale parallel applications compared with the existing algorithms.
Virtual interconnection of laboratories is a novel methodology for realization of large-scale simulation and testing infrastructures based on connection of hardware and software resources at geographically dispersed l...
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ISBN:
(纸本)9781538655412
Virtual interconnection of laboratories is a novel methodology for realization of large-scale simulation and testing infrastructures based on connection of hardware and software resources at geographically dispersed laboratories. The underlying concept of virtual interconnection of laboratories is Geographically distributedreal-time Simulation (GD-RTS). This paper focuses on GD-RTS of a High Voltage direct current (HVdc) link with a partitioning point at a dc cable. A co-simulation Interface Algorithm (IA) and a start-up procedure that together preserve simulation stability are introduced. Proposed guidelines are verified for GD-RTS of an HVdc link that interconnects transmission system benchmark model proposed by Council on Large Electric systems (CIGRE) and a simplified representation of an offshore wind farm.
In this paper, we present the design, implementation, and evaluation of an efficient data preparation and retrieval approach for cloud storage. The approach includes a deduplication subsystem that indexes the hash of ...
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Due to the increasing complexity of simulation models, the experiments conducted with these models become more complex as well. To date, software support for reproducible complex simulation experiments is constrained ...
Due to the increasing complexity of simulation models, the experiments conducted with these models become more complex as well. To date, software support for reproducible complex simulation experiments is constrained to specific application domains and experiment types. As a step towards a one-size-fits-all solution, we express simulation experiments as pure functions. With random number generation wrapped in the state monad, we achieve bit-level reproducibility of simulation results even for complex experiment setups. Additionally, we show how simulation runs can be executed in parallel without jeopardizing reproducibility. While the approach is independent of concrete simulation backends, we illustrate it by using NetLogo in various complex simulation experiments, utilizing design of experiments, simulation-based optimization, and statistical model checking.
In this paper, an hybrid distributed MPC strategy has been developed for teams of unmanned vehicle moving in uncertain and narrowed environments. The proposed solution does not require the exact knowledge of the obsta...
In this paper, an hybrid distributed MPC strategy has been developed for teams of unmanned vehicle moving in uncertain and narrowed environments. The proposed solution does not require the exact knowledge of the obstacle and /or corridor geometry. The resulting algorithm is conceived so that only the leader of the platoon within a corridor computes the admissible control actions that will be successively used by all the followers.
We present Accelerated Cyclic Reduction (ACR), a distributed-memory fast solver for rank-compressible block tridiagonal linear systems arising from the discretization of elliptic operators, developed here for three di...
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We present Accelerated Cyclic Reduction (ACR), a distributed-memory fast solver for rank-compressible block tridiagonal linear systems arising from the discretization of elliptic operators, developed here for three dimensions. Algorithmic synergies between Cyclic Reduction and hierarchical matrix arithmetic operations result in a solver that has O(k N logN (logN k(2))) arithmetic complexity and O(k NlogN) memory footprint, where N is the number of degrees of freedom and k is the rank of a block in the hierarchical approximation, and which exhibits substantial concurrency. We provide a baseline for performance and applicability by comparing with the multifrontal method with and without hierarchical semi-separable matrices, with algebraic multigrid and with the classic cyclic reduction method. Over a set of large-scale elliptic systems with features of nonsymmetry and indefiniteness, the robustness of the direct solvers extends beyond that of the multi grid solver, and relative to the multifrontal approach ACR has lower or comparable execution time and size of the factors, with substantially lower numerical ranks. ACR exhibits good strong and weak scaling in a distributed context and, as with any direct solver, is advantageous for problems that require the solution of multiple right-hand sides. Numerical experiments show that the rank k patterns are of O(1) for the Poisson equation and of O(n) for the indefinite Helmholtz equation. The solver is ideal in situations where low-accuracy solutions are sufficient, or otherwise as a preconditioner within an iterative method. (C) 2018 The Authors. Published by Elsevier B.V.
Most congestion control algorithms, like TCP, rely on a reactive control system that detects congestion, then marches carefully towards a desired operating point (e.g. by modifying the window size or adjusting a rate)...
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Priority heuristic policies have been developed for centralized and distributedrealtime database systems where cohorts or sub transaction executed in sequential manner, however, these heuristics may not fit well for...
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ISBN:
(纸本)9783319723440;9783319723433
Priority heuristic policies have been developed for centralized and distributedrealtime database systems where cohorts or sub transaction executed in sequential manner, however, these heuristics may not fit well for the mobile distributedrealtime database systems (MDRTDBS) where sub transactions are performing parallel execution and faces a lot of wireless challenges. In this paper, a MDRTDBS model has been introduced where sub-transaction executed parallel on different mobile sites and proposed a heuristic based on number of write locks. Proposed heuristic improves overall system performance by favoring sub transaction which demands lesser number of write locks. Further, a study has been done to evaluate impact of proposed heuristics with earliest deadline first and heuristic based on number of locks required using distributed high priority two phase locking protocol.
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