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arXiv 2021年

作者： Zhu, Wenqing Li, Zhi Shu, Hua Gao, Huajian Wei, Xiaoding State Key Laboratory for Turbulence and Complex System Department of Mechanics and Engineering Science College of Engineering Peking University Beijing100871 China School of Mechanical and Aerospace Engineering College of Engineering Nanyang Technological University 70 Nanyang Drive 637457 Singapore Shanghai Institute of Laser Plasma China Academy of Engineering Physics Shanghai201102 China Institute of High Performance Computing A*STAR 138632 Singapore Beijing Innovation Center for Engineering Science and Advanced Technology Peking University Beijing100871 China Peking University Nanchang Innovation Institute Nanchang330000 China

Theoretical predictions of the ideal strength of materials range from E/30 to E/10 (E is Young’s modulus). However, despite intense interest over the last decade, the value of the ideal strength that can be attained experimentally for metals remains a mystery (1-5). In this study, we demonstrated the unprecedented strength of an amorphous Cu-Zr alloy that surpassed the E/10 limit. Laser-induced shock experiments were conducted on Cu50Zr50 to explore its strength and failure mechanisms at ultrahigh strain rates. The material demonstrated a high spall strength of 9.8 GPa, approximately 1/13 of its P-wave modulus (~ E/6), at strain rates greater than 107 s−1, which sets a new record for the elastic limit of metallic materials. Electron microscopy and large-scale molecular dynamics simulations revealed that void nucleation and growth, not shear-banding, comprised the major failure mechanism for metallic glasses at extremely fast strain rates. A new model for void formation under the control of surface energy explained the rate dependence of the material strength. The results of this study reveal new possible ways to use the amorphous phase in nanostructured metals in future applications under demanding mechanical conditions. Copyright © 2021, The Authors. All rights reserved.

关键词： Copper alloys

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A Holistic Stream Partitioning Algorithm for Distributed Stream Processing systems

A Holistic Stream Partitioning Algorithm for Distributed Str...

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IEEE International Conference on Parallel and Distributed computing, Applications and Technologies (PDCAT)

作者： Kejian Li Gang Liu Minhua Lu Guangdong Province Key Laboratory of Popular High Performance Computers Guangdong Province Engineering Center of China-made High Performance Data Computing System College of Computer Science and Software Engineering Shenzhen University Shenzhen China School of biomedical engineering Shenzhen University Shenzhen China

ISBN: (数字)9781728126166

ISBN: (纸本)9781728126173

The performances of modern distributed stream processing systems are critically affected by the distribution of the load across workers. Skewed data streams in real world are very common and pose a great challenge to these systems, especially for stateful applications. Key splitting, which allows a single key to be routed to multiple workers, is a great idea to achieve good balance of load in the cluster. However, it comes with the cost of increased memory consumption and computation overhead as well as network communication. In this paper, we present a new definition of metric to model the cost of key splitting for intra-operator parallelism in stream processing systems and provide a novel perspective to reduce replication factor while keeping both overall load imbalance and processing latency low. Similar to previous work, our approach treats the head and the tail of the distribution differently in order to reduce memory requirements. For the head, it uses our proposed notion of regional load imbalance to decide dynamically whether to make one more worker responsible for the heavy hitter or not. For the tail, it simply uses hash partitioning to keep the size of the routing table for the head as small as possible. Extensive experimental evaluation demonstrates that our approach provides superior performance compared to the state-of-the-art partitioning algorithms in terms of load imbalance, replication factor and latency over different levels of skewed stream distributions.

关键词： Partitioning algorithms Memory management Measurement Parallel processing Microsoft Windows Load modeling Throughput

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The Library for Hadoop Deflate Compression Based on FPGA Accelerator with Load Balance

The Library for Hadoop Deflate Compression Based on FPGA Acc...

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IEEE International Conference on Parallel and Distributed computing, Applications and Technologies (PDCAT)

作者： Haixin Du Jiankui Zhang Shihao Sha Cai Ye Qiuming Luo College of Computer Science and Software Engineering Shenzhen University NHPCC/Guangdong Key Laboratory of popular HPC and Guangdong Province Engineering Center of China-made High Performance Data Computing System Shenzhen China

ISBN: (数字)9781728126166

ISBN: (纸本)9781728126173

Hadoop application will produce lots of intermediate results in the map/reduce process that requires disk I/O and network transmission. By compressing the large-scale data of intermediate result, it will greatly improve disk access efficiently and reduce program run time. Hardware-accelerated solutions have become more desirable. This paper design a multi-FPGA compression accelerator on the Hadoop platform, and the system performance analysis compared with a software-only solution that mainly uses CPU to processing. The testing programs are zpipe, TestDFSIO and Terasort. In contrast with the software-only solution. The max speedup of zpipe is 6.55X (single FPGA) and 10.24X (dual FPGA), the max speedup of TestDFSIO is 6.28X (single FPGA) and 6.28X (dual FPGA), and the max speedup of Terasort application is up to 3.25X(single FPGA) and 3.35X(dual FPGA).

关键词： Handheld computers Conferences Computer science Software engineering Distributed databases Indexes

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A plane wave study on the localized-extended transitions in the one-dimensional incommensurate systems

arXiv

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arXiv 2020年

作者： Chen, Huajie Zhou, Aihui Zhou, Yuzhi School of Mathematical Sciences Beijing Normal University Beijing100875 China LSEC Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing100190 China School of Mathematical Sciences University of Chinese Academy of Sciences Beijing100049 China Software Center for High Performance Numerical Simulation China Academy of Engineering Physics Beijing100088 China Institute of Applied Physics and Computational Mathematics Beijing100088 China

Based on our recently proposed plane wave framework, we theoretically study the localized-extended transition in the one dimensional incommensurate systems with cosine type of potentials, which are in close connection to many recent experiments in the ultracold atom and photonic crystal. We formulate a propagator based scattering picture for the transition at the ground state and single particle mobility edge, in which the deeper connection between the incommensurate potentials, eigenstate compositions and transition mechanism is revealed. We further show that there exists a upper limit of localization length for all localized eigenstates, leading to an fundamental difference to the Anderson localization. Numerical calculations are presented alongside the analysis to justify our statements. The theoretical analysis and numerical methods can also be generalized to systems in higher dimensions, with different potentials or beyond the single particle regime, which would benefit the future studies in the related fields. Copyright © 2020, The Authors. All rights reserved.

关键词： Elastic waves

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Implementing the Matrix Multiplication with DFC on Kunlun Small Scale Computer

Implementing the Matrix Multiplication with DFC on Kunlun Sm...

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IEEE International Conference on Parallel and Distributed computing, Applications and Technologies (PDCAT)

作者： Zheng Du Jing Zhang Shihao Sha Qiuming Luo Department of Computer Science and Technology Tsinghua University NHPCC/Guangdong Key Laboratory of popular UPC & Guangdong Province Engineering Center of China-made High Performance Data Computing System in College of Computer Science and Software Engineering Shenzhen University Shenzhen China

ISBN: (数字)9781728126166

ISBN: (纸本)9781728126173

In this paper, we demonstrate a new dataflow platform of DFC, which can handle the successive dataflow computing passes with tagged data. By implementing the matrix multiplication in DFC, we show that DFC can exploit the parallelism automatically with a much simple dataflow graph constructed by DF functions of DFC. Different from the other dataflow execution platform, DFC support multiple worker threads for one dataflow node of DF functions. By running the matrix multiplication program of DFC on Kunlun system, it was verified that DFC get a reasonable speedup for large scale computing for thread number up to 512.

关键词： Distributed computing Handheld computers

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In situ visualization infrastructure for large scale simulations with structured meshes 11

In situ visualization infrastructure for large scale simulat...

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11th International Conferences on Computer Graphics, Visualization, Computer Vision and Image Processing, CGVCVIP 2017 and International Conference on Big Data Analytics, Data Mining and Computational Intelligence, BigDaCI 2017

作者： Cao, Yi Mo, Zeyao Ai, Zhiwei Zhang, Aiqing Xiao, Li Wang, Huawei High Performance Computing Center Institute of Applied Physics and Computational Mathematics CAEP Software Center for High Performance Numerical Simulation Beijing China

ISBN: (纸本)9789898533661

To resolve complex multiscale, multiphysics problems at high resolution, modern large-scale parallel scientific and engineering simulations with structured meshes have exceeded the scale of tens of billions mesh elements. In situ visualization play an important role in avoiding the slowest component of post-processing workflow on exasale architectures: accessing the file system twice with input/output bottlenecks. Tightly coupling in situ visualization with simulations requires minimum modification to existing code. Most previous in situ work has focused on achieving in situ visualization with individual simulation code with less regard to the promising parallel programming frameworks that can guarantee quick adaptation to a batch of simulation applications. In this paper, we present an in situ visualization infrastructure based on the parallel programming framework, J Adaptive Structured Meshes applications Infrastructure (JASMIN), which supports large-scale simulations with structured meshes. We describe an approach that opens up new applications for in situ visualization, the key technologies on which it depends, and our experiences of integrating our infrastructure into two domain-specific simulations. © 2017.

关键词： Parallel programming

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Constraints on the two-dimensional pseudospin-12 Mott insulator description of Sr2IrO4

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Physical Review B 2022年第24期105卷 245130-245130页

作者： B. Zwartsenberg R. P. Day E. Razzoli M. Michiardi M. X. Na G. Zhang J. D. Denlinger I. Vobornik C. Bigi B. J. Kim I. S. Elfimov E. Pavarini A. Damascelli Quantum Matter Institute University of British Columbia Vancouver Canada BC V6T 1Z4 Department of Physics and Astronomy University of British Columbia Vancouver Canada BC V6T 1Z1 Max Planck Institute for Chemical Physics of Solids Nöthnitzer Straße 40 01187 Dresden Germany Key Laboratory of Materials Physics Institute of Solid State Physics HFIPS Chinese Academy of Sciences Hefei 230031 People's Republic of China Advanced Light Source Lawrence Berkeley National Laboratory Berkeley California 94720 USA Istituto Officina dei Materiali (IOM)-CNR Laboratorio TASC in Area Science Park S.S.14 Km 163.5 I-34149 Trieste Italy Dipartimento di Fisica Universit di Milano Via Celoria 16 I-20133 Milano Italy Department of Physics Pohang University of Science and Technology Pohang 790-784 South Korea Center for Artificial Low Dimensional Electronic Systems Institute for Basic Science (IBS) 77 Cheongam-Ro Pohang 790-784 Republic of Korea Max Planck Institute for Solid State Research Heisenbergstraße 1 D-70569 Stuttgart Germany Institute for Advanced Simulation Forschungszentrum Jülich D-52425 Jülich Germany JARA High-Performance Computing Forschungszentrum Jülich D-52425 Jülich Germany

Sr2IrO4 has often been described via a simple, one-band pseudospin-12 model subject to electron-electron interactions on a square lattice, fostering analogies with cuprate superconductors believed to be well described by a similar model. In this work we argue—based on a detailed study of the low-energy electronic structure by circularly polarized spin and angle-resolved photoemission spectroscopy combined with dynamical mean-field theory calculations—that a pseudospin-12 model fails to capture the full complexity of the system. We show instead that a realistic multiband Hubbard Hamiltonian, accounting for the full correlated t2g manifold, provides a detailed description of the interplay between spin-orbital entanglement and electron-electron interactions and yields quantitative agreement with experiments. Our analysis establishes that the j3/2 states make up a substantial percentage of the low-energy spectral weight, i.e., approximately 74% as determined from the integration of the j-resolved spectral function in the 0 to −1.64eV energy range. The results in our work are of relevance not only to Ir-based materials but also more generally to multiorbital materials with closely spaced energy scales.

关键词： Spin-orbit coupling high-temperature superconductors Mott insulators Angle-resolved photoemission spectroscopy Dynamical mean field theory Hubbard model Spin-resolved photoemission spectroscopy

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A Cache Enhanced Endorser Design for Mitigating performance Degradation in Hyperledger Fabric

A Cache Enhanced Endorser Design for Mitigating Performance ...

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IEEE/ACM Int'l Conference on & Int'l Conference on Cyber, Physical and Social computing (CPSCom) Green computing and Communications (GreenCom)

作者： Feng Lu Lu Gan Zhongli Dong Wei Li Hai Jin Albert Y. Zomaya Services Computing Technology and System Lab Huazhong University of Science and Technology China Center for Distributed and High Performance Computing University of Sydney NSW Australia

As a key technology that realises decentralised and highly trusted database management, Blockchain has recently attracted extensive attention. However, the high latency and low throughput in highly concurrent environments is the main performance bottleneck of Blockchain technology, and thus delays its deployment. Although multiple studies have been dedicated to solving the problem of low throughput in Blockchain, they only paid attention to the scenarios with large transactions volume while neglecting the issue of conflicting transactions. In this paper, we demonstrate that the conflict transactions will not only decrease the computing efficiency of Endorser but also slow down the performance of Hyperledger Fabric. Besides, we propose a Cache enhanced Endorser solution to tackle conflict transactions in Hyperledger Fabric vl.0. The experimental results show that our approach can reduce the workload of a node by up to 80%, shorten the turnaround time of transactions by 55%, and improve the computational performance of Endorser up to 1.9 times.

关键词： Blockchain Fabrics Throughput Peer-to-peer computing Security system performance Proposals

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Accumulative time-based ranking method to reputation evaluation in information networks

arXiv

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arXiv 2019年

作者： Liao, Hao Liu, Qi-Xin Huang, Ze-Cheng Yeung, Chi Ho Zhang, Yi-Cheng National Engineering Laboratory on Big Data System Computing Technology Guangdong Province Engineering Center of China-made High Performance Data Computing System College of Computer Science and Software Engineering Shenzhen University Shenzhen518060 China Institute of Big Data Intelligent Management and Decision Shenzhen University Shenzhen518060 China Department of Science and Environmental Studies The Education University of Hong Kong Hong Kong Hong Kong Department of Physics University of Fribourg Fribourg Switzerland

With the rapid development of modern technology, the Web has become an important platform for users to make friends and acquire information. However, since information on the Web is over-abundant, information filtering becomes a key task for online users to obtain relevant suggestions. As most Websites can be ranked according to users’ rating and preferences, relevance to queries, and recency, how to extract the most relevant item from the over-abundant information is always a key topic for researchers in various fields. In this paper, we adopt tools used to analyze complex networks to evaluate user reputation and item quality. In our proposed accumulative time-based ranking (ATR) algorithm, we incorporate two behavioral weighting factors which are updated when users select or rate items, to reflect the evolution of user reputation and item quality over time. We showed that our algorithm outperforms state-of-the-art ranking algorithms in terms of precision and robustness on empirical datasets from various online retailers and the citation datasets among research publications. Copyright © 2019, The Authors. All rights reserved.

关键词： Information filtering

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The effects of different travel modes and travel destinations on COVID-19 transmission in global cities

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Science Bulletin 2022年第6期67卷 588-592,M0003页

作者： Rui Zhu Luc Anselin Michael Batty Mei-Po Kwan Min Chen Wei Luo Tao Cheng Che Kang Lim Paolo Santi Cheng Cheng Qiushi Gu Man Sing Wong Kai Zhang Guonian Lü Carlo Ratti Department of Land Surveying and Geo-Informatics the Hong Kong Polytechnic UniversityHong KongChina Key Laboratory of Virtual Geographic Environment(Ministry of Education) Nanjing Normal UniversityNanjing 210023China Senseable City Laboratory Future Urban Mobility IRGSingapore-MIT Alliance for Research and TechnologySingapore 138602Singapore Center for Spatial Data Science Division of the Social SciencesUniversity of ChicagoChicago IL 60637USA School of Geography Science Nanjing Normal UniversityNanjing 210023China Centre for Advanced Spatial Analysis Faculty of the Built EnvironmentUniversity College LondonLondon WC1E 6BTUK Department of Geography and Resource Management the Chinese University of Hong KongHong KongChina Institute of Space and Earth Information Science the Chinese University of Hong KongHong KongChina Department of Human Geography and Spatial Planning Utrecht UniversityUtrecht 3584 CSNetherlands State Key Laboratory Cultivation Base of Geographical Environment Evolution Nanjing 210023China Department of Geography National University of SingaporeSingapore 117570Singapore SpaceTimeLab Department of CivilEnvironmental and Geomatic EngineeringUniversity College LondonLondon WC1E 6BTUK Department of Clinical Translational Research Singapore General HospitalSingapore 169856Singapore Division of Clinical Immunology and Transfusion Medicine Department of Laboratory MedicineKarolinska InstitutetStockholm 17177Sweden Senseable City Laboratory Department of Urban Studies and PlanningMassachusetts Institute of TechnologyCambridgeMA 02139USA Istituto di Informatica e Telematica del CNR Pisa 56124Italy Department of System Science Institute of High Performance Computing Agency for ScienceTechnology and ResearchSingapore 138632Singapore Department of Tourism Studies School of HumanitiesSoutheast UniversityNanjing 210096China

The international community has made significant efforts to flatten the COVID-19 curve,including predicting transmission[1,2],executing unprecedented global lockdowns and social distancing[3,4],promoting the wearing of facemasks and social distancing measures[5],and isolating confirmed cases and contacts[6].Because of the adverse consequences of these lockdown measures[7],many cities have reopened so they can rebuild their ***,as mobility has gradually returned towards normal,imported cases from unknown sources have disrupted the recovery situation,and cities are continually at high risk of new waves of infection[8,9]since airborne transmission is the dominant transmission route[10].

关键词：多变量时间序列疫情传播出行方式谷歌公司交通出行病毒传播出行行为大城市

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