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Neutronic calculations of the China dual-functional lithium–lead test blanket module with the parallel discrete ordinates code Hydra

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Nuclear Science and Techniques 2020年第8期31卷 1-12页

作者： Guang-Chun Zhang Jie Liu Liang-Zhi Cao Hong-Chun Wu Xian-Bao Yuan Science and Technology on Parallel and Distributed Processing Laboratory National University of Defense TechnologyChangsha 410073China Laboratory of Software Engineering for Complex Systems National University of Defense TechnologyChangsha 410073China School of Nuclear Science and Technology Xi’an Jiaotong UniversityXi’an 710049China College of Mechanical and Power Engineering China Three Gorges UniversityYichang 443002China

The China dual-functional lithium–lead test blanket module(DFLL-TBM) is a liquid Li Pb blanket concept developed by the Institute of Nuclear Energy Safety Technology of the Chinese Academy of Sciences for testing in ITER to validate relevant tritium breeding and shielding technologies. In this study, neutronic calculations of DFLL-TBM were carried out using a massively parallel three-dimensional transport code, Hydra, with the Fusion Evaluated Nuclear Data Library/MG. Hydra was developed by the Nuclear Engineering Computational Physics Lab based on the discrete ordinates method and has been devoted to neutronic analysis and shielding evaluation for nuclear facilities. An in-house Monte Carlo code(MCX) was employed to verify the discretized calculation model used by Hydra for the DFLL-TBM calculations. The results showed two key aspects:(1) In most material zones,Hydra solutions are in good agreement with the reference MCX results within 1%, and the maximal relative difference of the neutron flux is merely 3%, demonstrating the correctness of the calculation model;(2) while the current DFLL-TBM design meets the operation shielding requirement of ITER for 4 years, it does not satisfy the tritium self-sufficiency requirement. Compared to the two-step approach, Hydra produces higher accuracies as it does not rely on the homogenization technique during the calculation process. The parallel efficiency tests of Hydra using the DFLL-TBM model also showed that this code maintains a high parallel efficiency on O(100) processors and, as a result, is able to significantly improve computing performance through parallelization. Parameter studies have been carried out by varying the thickness of the beryllium armor layer and the tritium breeding zone to understand the influence of the beryllium layer and breeding zone thickness on tritium breeding performance. This establishes a foundation for further improvement in the tritium production performance of DFLL-TBM.

关键词： Discrete ordinates method DFLL-TBM Neutronic analysis Tritium breeding performance

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Pillow talks: Bits over communications in WLAN 2

Pillow talks: Bits over communications in WLAN

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2nd Workshop for Mobile Sensing, Computing and Communication, MSCC 2015

作者： Dong, Xuan Zhu, Chunsheng Lv, Shaohe Wang, Lei Wang, Xiaodong Leung, Victor C.M. National Laboratory of Parallel and Distributed Processing National University of Defense Technology United States Department of Electrical and Computer Engineering University of British Columbia Canada Department of Network Engineering Dalian University of Technology China

ISBN: (纸本)9781450335188

Improving the channel utilization is a significant issue to enhance the performance in WLAN. This paper presents, Pillow Talks MAC (PT-MAC), a novel spectrum sharing mechanism to create an extra channel (pt-channel) for client- to-client transmission in WLAN. Obviously, The basic chal- lenge in our proposal is how pt-channel works concurrently and transparently with AP transmissions. To address the issue, in PT-MAC, selected clients are allowed to contend for pt-channel during uplink transmissions and talk freely under the ongoing downlink transmissions. Based on ad- vanced physical techniques, pt-channel transmitter receives and forwards the AP signals simultaneously within OFDM cyclic prefix, resulting in mixed signals are overheard by re- ceiver in pt-channel. However, the mixed message can be re- covered by pt-decoding system. Simulations and analytical results show that, PT-MAC reuses the spectrum in WLAN and achieves a throughput gain as large as 92% with similar fairness, when the ratio of downlink traffic is about 80%. © 2015 ACM.

关键词： Wireless local area networks (WLAN)

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Component model supporting trustworthiness-oriented software evolution

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Ruan Jian Xue Bao/Journal of Software 2011年第1期22卷 17-27页

作者： Ding, Bo Wang, Huai-Min Shi, Dian-Xi Li, Xiao School of Computer National University of Defense Technology Changsha 410073 China National Defense Laboratory for Parallel and Distributed Processing Changsha 410073 China

Environment-Driven adaptation is an important means ensuring software integrity. Confronted with scenarios not anticipated during the developmental stage, the predefined adaptability of the software should be adjusted to ensure that its behavior agree with the users' expectation. The premise of this kind of adjustment are efficient software engineering mechanisms. Based on the principles of the Separation of Concerns and the Dynamic Software Architecture (DSA) technology, this paper proposes a component model named ACOE (adaptive component model for open environment) that supports the online fine-grained adjustment to software adaptability. ACOE encapsulates adaptation concerns, such as sensing, decision, and execution into components, and connectors, and then supports their dynamic configuration with the DSA technology. As a result, a third-party can adjust the adaptability by selectively upgrading it when necessary. An ACOE container prototype and experimental applications are implemented to validate this approach. © Copyright 2011, Institute of Software, the Chinese Academy of Sciences. All rights reserved.

关键词： Memory architecture

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Algorithm for distributed Constraint Optimization Problems with low constraint density

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Ruan Jian Xue Bao/Journal of Software 2011年第4期22卷 625-639页

作者： Ding, Bo Wang, Huai-Min Shi, Dian-Xi Tang, Yang-Bin School of Computer National University of Defense Technology Changsha 410073 China National Key Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha 410073 China

Many challenges in multi-agent coordination can be modeled as distributed Constraint Optimization Problems (DCOPs). Aiming at DCOPs with low constraint density, this paper proposes a distributed algorithm based on the idea of greed and backjumping. In this algorithm, each agent makes decisions according to the greedy principle that the most assignment combinations in the problems with low constraint density occur at a zero cost, and the backjumping mechanism among the agents ensures the success of this algorithm, even when this greedy principle leads to a local optimum. In contrast with the existing mainstream DCOP algorithms, this algorithm can solve problems with low constraint density with fewer messages while keeping the polynomial message length and space complexity. The correctness of the key mechanisms in this algorithm has been proved, and those advantages in performance have been verified by experiments. © 2011 ISCAS.

关键词： Multi agent systems

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Weakly hard real-time scheduling algorithm for multimedia embedded system on multiprocessor platform

Weakly hard real-time scheduling algorithm for multimedia em...

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IEEE International Conference on Ubi-Media Computing

作者： Tong Wu Shiyao Jin NUDT Changsha Hunan National Laboratory for Parallel and Distributed Processing China

ISBN: (纸本)9781424418657

Multiprocessor architectures are becoming more attractive for embedded systems, and also for multimedia embedded systems. In multimedia embedded systems, there exist both hard real-time tasks and multimedia stream with QoS guarantee. In this context, researched on integrated schedule of both hard real-time tasks and streams are urgent affairs. This paper analyzes the shortcomings of the current approach - multimedia server, and then based on the DBP algorithm, proposes an algorithm which also considers the resource constraint. According to the different budget schemes, greedy algorithm and optimistic algorithm are brought up. Results show the performance of the algorithms.

关键词： Real time systems Scheduling algorithm Multimedia systems Embedded system Streaming media Processor scheduling Job shop scheduling Very large scale integration Computer architecture Laboratories

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Communication-Aware Task Partition and Voltage Scaling for Energy Minimization on Heterogeneous parallel Systems

Communication-Aware Task Partition and Voltage Scaling for E...

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IEEE International Conference on parallel and distributed Computing, Applications and Technologies (PDCAT)

作者： Guibin Wang Wei Song National Laboratory for Parallel and Distributed Processing National University of Defense Technology China

Heterogeneous parallel systems have become popular in general purpose computing and even high performance computing fields. There are many studies focused on harnessing heterogeneous parallel processing for better performance. However the energy optimization for heterogeneous system has not been well studied. Owing to the differences in performance and energy consumption, the energy optimization technique for heterogeneous system is different from the existing methods designed for homogeneous system. Besides typical voltage scaling method, reasonable task partitioning is also an essential method for optimizing energy consumption on heterogeneous systems. Through partitioning a data parallel task and mapping sub-tasks onto several processors, one could achieve better performance and reduced energy consumption. As the computation cost reduces with specific accelerators, the communication overhead becomes more prominent. Therefore, the task partition optimization should holistically consider the computation improvement and communication overhead to achieve higher energy efficiency. Typically, task partition and voltage scaling are not orthogonal and influence the effect of each other in the energy optimization problem. In order to harness both two knobs efficiently, this paper proposes an integer linear programming (ILP) based energy-optimal solution designed for heterogeneous system. We present a case study of optimizing MGRID benchmark on a typical CPU-GPU heterogeneous system. The experimental results demonstrate that the proposed method could exploit the heterogeneity in different processors and achieve improved energy efficiency.

关键词： Graphics processing unit Energy consumption Power demand Optimization Kernel Schedules

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Fast query over encrypted data based on B+ tree

Fast query over encrypted data based on B+ tree

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2009 International Conference on Apperceiving Computing and Intelligence Analysis, ICACIA 2009

作者： Wang, Zheng-Fei Tang, Ai-Guo Wang, Wei Department of Computer Hunan Business College Changsha 410205 China National Key Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha 410073 China School of Computer Science Fudan University Shanghai 200433 China

ISBN: (纸本)9781424452040

There are a lot of important and sensitive data in databases, which need to be protected from attacks. To secure the data, Cryptography support is an effective mechanism. However, a tradeoff must be made between the performance and the security because encryption and decryption greatly degrade the query performance. In this paper, a framework is proposed that can quickly implement query over encrypted data based on B+ tree. When data are stored in the form of cipher, it not only stores the encrypted data themselves, but also creates a B+ tree index for the data before encrypting them. When querying the encrypted data, firstly, it locates the encrypted records related to the querying predicate based on the B+ tree index;secondly, it decrypts the encrypted records to accomplish the results. Meanwhile, it must encrypt the B+ tree itself to protect it from leaking confidential information. According to the structure of the B+ tree, it encrypts each node of the B+ tree separately. The results of experiments show that the query performance over the encrypted data decreases about 20 percent compared with the plaintext query performance, and validate the functionality and usability of our approach. ©2009 IEEE.

关键词： Cryptography

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Design of an Indoor Exploration and Multi-Objective Navigation System 37

Design of an Indoor Exploration and Multi-Objective Navigati...

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37th Chinese Control Conference, CCC 2018

作者： Zheng, Guoxian Zhang, Lei Zhang, Huaxi Yulin Ding, Bo State Key Laboratory of Synthetical Automation for Process Industries Northeastern University Shenyang110819 China MIS INSSET Universite de Picardie Jules Verne Amiens80039 France National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha410008 China

ISBN: (纸本)9789881563941

In this paper, we propose an indoor robot autonomous navigation system. The robot firstly explores in an unknown environment, and then navigates autonomously by using the explored map. The robot is equipped a 2D laser scanner as the main sensor. The laser scanner is used for path planning and frontier-based exploration. A 2D global occupancy map is built for path planning, frontier-based exploration and multi-objective autonomous navigation. Laser scans are transmitted into Simultaneous Localization and Mapping (SLAM) process in the exploration phase. In indoor environment, the exploration efficiency is improved by merging a heuristic algorithm. By using multi-threading technology and a 3D perception approach proposed in this paper, the robot equipped with a low-cost RGBD sensor can detect all kinds of obstacles to achieve highly reliable navigation in complicated 3D environment. Meanwhile, we develop a multi-objective navigation application to make human-robot interaction more convenient and satisfy multi-task deployment. Our approaches are demonstrated by experimental results. © 2018 Technical Committee on Control Theory, Chinese Association of Automation.

关键词： Motion planning

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Efficient Management and Intelligent Fault Tolerance for HPC Interconnect Networks

Efficient Management and Intelligent Fault Tolerance for HPC...

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International Conference on parallel and distributed Systems (ICPADS)

作者： Jijun Cao Mingche Lai Zhang Luo jiaqing Xu Zhengbin Pang College of Computer National Laboratory for Parallel and Distributed Processing ChangSha China

ISBN: (纸本)9781728125848

Interconnect Network is the key component in high performance computing system. With the incoming era of Exa-Scale (10 18 FLOPS) computing, designing large scale interconnect networks is facing with serious challenges in network management and fault tolerance. To construct higher performance and more reliable interconnect networks, we propose an efficient and intelligent network management architecture for indirect interconnect networks. This paper emphatically introduces the network management architecture, the in-band management channels in the Network Interface Chips (NIC) and Network Routing Chips (NRC) respectively, efficient centralized network management approach, distributed intelligent faulttolerant routing management, and so on. Based on the prototype system, the Control and Status Registers (CSR) accessing latency performance of in-band network management is evaluated. Also based on a customized simulation model for indirect interconnect networks, the typical distributed fault-tolerant scenes are tested. The experiment results show the in-band network management can averagely achieves 716 times improvements than the out of-band network management. Moreover, by running heuristic algorithms to automatically reconstruct routing tables for failure links or routers, the intellectual network management Engine can achieve fault-tolerant routing to maximizing network performance.

关键词： High performance computing system Interconnect network Network management Fault tolerate Network management Fault tolerance High Performance Computing unified network management architecture Network Network routing

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Towards building efficient content-based publish/subscribe systems over structured P2P overlays

Towards building efficient content-based publish/subscribe s...

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International Conference on parallel processing

作者： Zhang, Shengdong Wang, Ji Shen, Rui Xu, Jie National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China School of Computing University of Leeds Leeds LS2 9JT United Kingdom

ISBN: (纸本)9780769541563

In this paper, we introduce a generic model to deal with the event matching problem of content-based publish/ subscribe systems over structured P2P overlays. In this model, we claim that there are three methods (eventoriented, subscription-oriented and hybrid) to make all the matched pairs (event, subscription) meet in a system. By theoretically analyzing the inherent problem of both eventoriented and subscription-oriented methods, we propose PEM (Popularity-based Event Matching), a variant of hybrid method. PEM can achieve better trade-off between event processing load and subscription storage load of a system. PEM has been verified through both mathematical and simulation-based evaluation. © 2010 IEEE.

关键词： Message passing

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