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AIAA SciTech Forum

作者： Dzanic, Tarik Martinelli, Luigi Lawrence Livermore Natl Lab Ctr Appl Sci Comp Livermore CA 94550 USA Princeton Univ Dept Mech & Aerosp Engn Princeton NJ 08544 USA

ISBN: (数字)9781624107115

ISBN: (纸本)9781624107115

This work explores the feasibility of performing three-dimensional molecular gas dynamics simulations of hypersonic flows such as re-entry vehicles through directly solving the six-dimensional nonlinear Boltzmann equation closed with the BGK (Bhatnagar-Gross-Krook) collision model. Through the combination of high-order unstructured spatial discretizations and conservative discrete velocity models as well as their efficient implementation on large-scale GPU computing architectures, we demonstrate the ability to simulate unsteady and non-equilibrium three-dimensional high-speed flows at a feasible computational cost through a unified numerical framework. We present the results of high-order simulations of the Apollo capsule at realistic re-entry conditions from the AS-202 mission flight path, including the steady non-equilibrium flow in the high-altitude regime at a Mach number of 22.7 and a Reynolds number of 43,000 as well as the unsteady turbulent flow in the low-altitude regime at a Mach number of 8 and a Reynolds number of 550,000. The results show the validity of the approach over the entire range of a typical re-entry trajectory from the rarefied to the continuum limit, the ability to directly resolve strong shocks profiles without numerical shock capturing techniques, and the ability of resolving small-scale unsteady flow structures in the inertial range.

关键词： Boltzmann Equation Re Entry Vehicle Knudsen Number Freestream Velocity Three Dimensional Turbulent Flow Computational Fluid Dynamics computing architecture Re Entry Trajectories Discontinuous Spectral Element Method Shock Layers

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Parallel simulation of high-speed trains controlled by radio block centers using Spark cloud

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ADVANCES IN MECHANICAL ENGINEERING 2023年第7期15卷

作者： Tao, Xin Zhou, Yonghua Mei, Yiduo Fujita, Hamido Beijing Jiaotong Univ Sch Elect & Informat Engn Beijing Peoples R China Zhongguancun Smart City Co Ltd Beijing Peoples R China Iwate Prefectural Univ Fac Software & Informat Sci Iwate Japan Beijing Jiaotong Univ Sch Elect & Informat Engn Beijing 100044 Peoples R China Zhongguancun Smart City Co Ltd Beijing 100081 Peoples R China

Train movement prediction simulation is an effective method of enhancing operation safety and efficiency of railway transportation. Train movement data generated by the trains running in a railway network are huge, and on the other hand, the data quantity generated from data processing is also explosively increased for the analysis and decision such as conflict recognition and scheduling optimization, which greatly increases the time cost of prediction simulation. This paper attempts to propose a train movement model driven by the movement authorities (MAs) issued from radio block centers (RBCs) and its parallel simulation algorithm realized on Spark cloud. This paper provides a solution of iterative computing of dynamic process simulation based on cloud. Different from the general big data processing of independent datasets, the resilient distributed datasets are expandable along iterative computing processes. The Dataframe of SparkSQL modules on Apache Spark is employed to handle the problems of usage interdependency of datasets. The parallel simulation is realized by Scala language that is used to build the Spark platform. The simulation results on a high-speed railway network demonstrates that the proposed train movement model and parallel algorithm can achieve theoretical rationality and decrease the time cost to satisfy real-time performance.

关键词： Parallel iterative computing big data processing Spark cloud computing architecture modeling and simulation high-speed train movement

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Implementation of NVMe over TCP using SPDK and Its Performance Measurement

Implementation of NVMe over TCP using SPDK and Its Performan...

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IEEE International Workshop on Technical Committee on Communications Quality and Reliability (IEEE CQR)

作者： Oyama, Tatsuki Shiomoto, Kohei Tokyo City Univ Fac Informat Technol Dept Intelligent Syst Tokyo Japan

ISBN: (纸本)9798331540739;9798331540722

In data centers, massive GPGPUs and SSDs are employed to implement massively parallel computing and high-speed huge data storage. To meet the demand for such computing facilities, we believe that disaggregated computer architecture are effective, i.e., provisioning GPGPU clusters and SSD clusters separately and interconnecting these clusters based on NVMe over Fabrics (NVMe-oF) standard. In this paper, we report an implementation of NVMe over TCP, an architecture based on NVMe over Fabrics standard, using the Storage Performance Development Kit (SPDK) and performance measurement.

关键词： deep learning computing architecture storage SSD NVMe over Fabrics

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PIT: Processing-In-Transmission With Fine-Grained Data Manipulation Networks

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IEEE TRANSACTIONS ON COMPUTERS 2021年第6期70卷 877-891页

作者： Zong, Pengchen Xia, Tian Zhao, Haoran Tong, Jianming Li, Zehua Zhao, Wenzhe Zheng, Nanning Ren, Pengju Xi An Jiao Tong Univ Sch Elect Sci & Engn Xian 710049 Shaanxi Peoples R China

In the domain of data parallel computation, most works focus on data flow optimization inside the PE array and favorable memory hierarchy to pursue the maximum parallelism and efficiency, while the importance of data contents has been overlooked for a long time. As we observe, for structured data, insights on the contents (i.e., their values and locations within a structured form) can greatly benefit the computation performance, as fine-grained data manipulation can be performed. In this paper, we claim that by providing a flexible and adaptive data path, an efficient architecture with capability of fine-grained data manipulation can be built. Specifically, we design SOM, a portable and highly-adaptive data transmission network, with the capability of operand sorting, non-blocking self-route ordering and multicasting. Based on SOM, we propose the processing-in-transmission architecture (PITA), which extends the traditional SIMD architecture to perform some fundamental data processing during its transmission, by embedding multiple levels of SOM networks on the data path. We evaluate the performance of PITA in two irregular computation problems. We first map the matrix inversion task onto PITA and show considerable performance gain can be achieved, resulting in 3x-20x speedup against Intel MKL, and 20x-40x against cuBLAS. Then we evaluate our PITA on sparse CNNs. The results indicate that PITA can greatly improve computation efficiency and reduce memory bandwidth pressure. We achieved 2x-9x speedup against several state-of-art accelerators on sparse CNN, where nearly 100 percent PE efficiency is maintained under high sparsity. We believe the concept of PIT is a promising computing paradigm that can enlarge the capability of traditional parallel architecture.

关键词： Sorting Switches Topology Network topology Computer architecture Sparse matrices Task analysis computing architecture transmission network irregular computation hiph-performance computing

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Mixed-Precision Variational Multiscale Modeling with Discontinuous Subscales for Scalar Transport

Mixed-Precision Variational Multiscale Modeling with Discont...

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AIAA Aviation Forum and Exposition

作者： Coley, Christopher US Air Force Acad Dept Aeronaut Colorado Springs CO 80840 USA

ISBN: (数字)9781624106101

ISBN: (纸本)9781624106101

We present a mixed-precision variational multiscale method with discontinuous subscales in which the fine-scales are represented in reduced-precision floating-point format while the coarse-scales are represented in double-precision floating-point format. We show that the memory overhead of the variational multiscale method can be reduced by 75% and that the total memory requirements are reduced by 56% in the case of standard finite element discretizations and 58% in the case of isogeometric NURBS discretizations by representing the fine-scales in half-precision floating-point format. We apply the mixed-precision variational multiscale method to unsteady scalar transport problems, and demonstrate that the method is stable and accurate in the advection limit.

关键词： Variational Multiscale Method Advection Discontinuous Galerkin Method Peclet Number Large Eddy Simulation Dirichlet Boundary Condition Mathematical Analysis computing architecture Turbulence Models Turbulent Flow

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Future communication satellites: low cost reduction of technology obsolescence

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Aerospace Systems 2021年第4期4卷 301-314页

作者： Periola, Ayodele Feng, Louis Wei-Yu Computer and Telecommunications Engineering Bells University of Technology Ota Nigeria Feng Consulting International Somerset West Cape Town South Africa

Rapid technological advances cause the obsolescence of communication satellite payload at the launch epoch. The software defined radio (SDR) is reconfigurable and is suitable to address technological obsolescence in satellites. However, SDRs have a finite flexibility and reconfigurability. This paper proposes the use of high-altitude platforms (HAPs) with low launch costs to reduce technology obsolescence in satellites. The SDR on the HAP can be easily upgraded and does not need radiation hardening to survive in space. The HAP is a virtual extension of an in-orbit satellite and they are jointly referred to as cloud aided satellite (CAS). This paper proposes the use of open source hardware for the CAS to lower the payload acquisition costs and the use of neuromorphic hardware instead of Von Neumann hardware in satellite communications. Results show that the incorporation of CAS and neuromorphic hardware enhances system performance, where the data transmit power, downlink channel capacity are improved by an average of up to 45.7% and 34.2%, respectively. Lastly, the use of the HAPs in the proposed CAS also reduces the forwarding latency by 14.4% on average. © 2021, Shanghai Jiao Tong University.

关键词： Communication satellites computing architecture High-altitude platforms Software defined radios

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Edge-Based Viscous Method for Node-Centered Formulations

Edge-Based Viscous Method for Node-Centered Formulations

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AIAA Aviation Forum and Exposition

作者： Liu, Yi Disking, Boris Anderson, William K. Nielsen, Eric J. Wang, Li Natl Inst Aerosp Hampton VA 23666 USA NASA Langley Res Ctr Computat Aerosci Branch Hampton VA 23681 USA

ISBN: (数字)9781624106101

ISBN: (纸本)9781624106101

This paper presents a novel, efficient, conservative, edge-based method for evaluation of meanflow viscous fluxes and turbulence-model diffusion terms of the Reynolds-averaged Navier-Stokes equations on tetrahedral grids. The new method is implemented in a practical, node-centered, finite-volume computational fluid dynamics solver. The baseline finite-volume scheme that is equivalent to a second-order accurate finite-element Galerkin approximation of viscous stresses is reformulated. The order of operations to compute the cell-based Green-Gauss gradients is changed to combine the operations by edge, which leads to an equivalent formulation on tetrahedral grids, improves efficiency, and preserves the compact discretization stencil based on the nearest neighbors. The computational results presented in this paper verify the implementation of this edge-based method by comparing its accuracy and iterative convergence with those of the well verified and validated baseline formulation. Efficiency gains for residual and Jacobian evaluations result in significant reduction of time to solution. This novel edge-based formulation on tetrahedra can be seamlessly combined with the baseline formulation on cells of other types for computing solutions on mixed-element grids.

关键词： Computational Fluid Dynamics Reynolds Averaged Navier Stokes Turbulence Models computing architecture Finite Volume Method FUN3D Kinematic Viscosity Aerodynamic Coefficients Nonequilibrium Flows Lift Coefficient

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ENAS oriented layer adaptive data scheduling strategy for resource limited hardware

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NEUROcomputing 2020年第0期381卷 29-39页

作者： Li, Chuxi Fan, Xiaoya Geng, Yuling Yang, Zhao Wang, Danghui Zhang, Meng Northwestern Polytech Univ Minist Educ Sch Comp Sci Engn & Res Ctr Embedded Syst Integrat Xian 710129 Peoples R China

Efficient Neural architecture Search (ENAS) is an effective solution for building deep Convolutional Neural Network (CNN) models automatically. However, it is confronted with challenges when concerning deploying the searched networks on embedded platforms under limited resources. The key issue is the mismatch between the traditional data scheduling and the irregularity of layers from ENAS searched networks, which results in remarkable bandwidth pressure increment, and further leads to performance degradation and power consumption increase. In this paper, three alternative data scheduling patterns are constructed for different layers from ENAS searched networks, and a layer adaptive data scheduling strategy is proposed according to the constrained resources given by embedded platforms. Additionally, an adaptive architecture is also presented to deploy the searched networks efficiently, providing 4-10x performance speedup and 2.5-6x power consumption saving. (C) 2019 Elsevier B.V. All rights reserved.

关键词： Efficient neural architecture search Resource limited hardware Hardware deployment computing architecture Data scheduling strategy

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Control Software: Research Directions in the Intersection of Control Theory and Software Engineering

Control Software: Research Directions in the Intersection of...

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AIAA Science and Technology Forum and Exposition (AIAA SciTech)

作者： Bradley, Justin Bagheri, Hamid Univ Nebraska Lincoln Dept Comp Sci & Engn Lincoln NE 68508 USA

ISBN: (数字)9781624105951

ISBN: (纸本)9781624105951

Control theory and Software Engineering are well established research fields. Their intersection occurs in every computer-controlled system as control laws, sampling rates, derivatives, integrals, sensor readings, and control actuations are implemented in code and executed by the computer. The execution of controllers has received the bulk of attention from researchers in this intersection while their actual software implementation has received comparatively little. This intersection warrants increased attention from researchers for two main reasons: 1) control systems are distinct from much of the research in software engineering due to the focus on computing for the physical world (e.g., motor actuation, sensor readings, velocity calculations), need for deterministic timing, and safety-critical nature, and 2) correctness and performance guarantees are only meaningful if, in addition to the model, they also characterize the software implementation and its execution - something many in the control community take for granted. In this paper we identify the need for increased research at this intersection by focusing on control software - an area distinct from, but informed by both control theory and software engineering disciplines. This area is complementary to the verification community which focuses on models and testing but may not examine the development process or the software itself, its evolution, semantics, maintainability, or longevity. We identify two key areas in this domain worthy of increased attention. First, successful controllers, their models, and software evolve over their lifetime. Understanding how controllers evolve can help designers know what types of changes impact important controller properties such as margins of stability, rise time, settling time, etc. We discuss this challenge in detail and report on our recent research to characterize controller evolution, including the development of a tool to rapidly simulate it and characterize its im

关键词： Software Engineering Model Based Design Robust Control System computing architecture Sensors Software Development Ardupilot Unmanned Aircraft System Commercial Aircraft Safety Critical Software

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A Data-Handling Module for the Hermes Compiler

A Data-Handling Module for the Hermes Compiler

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AIAA Science and Technology Forum and Exposition (AIAA SciTech)

作者： Easterling, David R. Durscher, Ryan Univ Dayton Res Inst Dayton OH 45469 USA Air Force Res Lab Wright Patterson AFB OH 45433 USA

ISBN: (数字)9781624105951

ISBN: (纸本)9781624105951

This paper describes the Arachne expansion to the Hermes cross-language remote procedure call framework. The original Hermes framework is a powerful and flexible tool developed for an evolving software suite for multidisciplinary design as an intermediary between direct processor communications and larger distributed frameworks. Given the differences in processor utilization across disciplines, this creates an easily utilized way to decouple the client and server to preserve implementation agnosticism on either side. While this default configuration is easily incorporated for anyone wishing to decouple multiprocessor servers and clients, it lacks an easy way to map different numbers of processors together from one side of the connection to the other, relying on direct processor-to-processor communications. As a result, any attempt to reorder the domain for use by differing numbers of processors relies on the development of an additional application-dependent interface to handle this communication. Arachne adds additional functionality to allows agnostic requests that map client and server processors. This enables more efficient computing as the data environment shifts between disciplines. This paper demonstrates the utility of this approach with an application to an aeroelastic problem couplings independent aerodynamic and structural solvers.

关键词： computing architecture Computer Programs Aeroelastic Analysis Aircraft Wings FUN3D Sensitivity Analysis Structural Modeling Data Structures Mach Number Black Box

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