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arXiv 2019年

作者： Slak, J. Kosec, G. "Jožef Stefan" Institute Parallel and Distributed systems Laboratory Jamova 39 Ljubljana1000 Slovenia

This paper considers a numerical solution of a linear elasticity problem, namely the Cauchy-Navier equation, using a strong form method based on a local Weighted Least Squares (WLS) approximation. The main advantage of the employed numerical approach, also referred to as a Meshless Local Strong Form method, is its generality in terms of approximation setup and positions of computational nodes. In this paper, flexibility regarding the nodal position is demonstrated through two numerical examples, i.e. a drilled cantilever beam, where an irregular domain is treated with a relatively simple nodal positioning algorithm, and a Hertzian contact problem, where again, a relatively simple h-refinement algorithm is used to extensively refine discretization under the contact area. The results are presented in terms of accuracy and convergence rates, using different approximations and refinement setups, namely Gaussian and monomial based approximations, and a comparison of execution time for each block of the solution *** Codes 65N99, 74B05 Copyright © 2019, The Authors. All rights reserved.

关键词： Cantilever beams

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parallel computing for large-scale author name disambiguation in medline 21

Parallel computing for large-scale author name disambiguatio...

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21st IEEE International Conference on High Performance Computing and Communications, 17th IEEE International Conference on Smart City and 5th IEEE International Conference on Data Science and systems, HPCC/SmartCity/DSS 2019

作者： Tang, Anyao Wu, Chengkun Liu, Jie Wang, Wei Yang, Xi Xing, Yuting Science and Technology on Parallel and Distributed Processing Laboratory Laboratory of Software Engineering for Complex Systems National University of Defense Technology Changsha410073 China State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology Changsha410073 China College of Computer National University of Defense Technology Changsha 410073 China

ISBN: (纸本)9781728120584

Author name disambiguation (AND) is an important task in the field of scientific data mining. It has become a great challenge with the rapid growth of academic digital libraries. The task of AND for a large number of authors is computationally intensive. In particular, an author's name in MEDLINE is represented by full last name and initials, like 'Zhang S', which leads to a lot of identical strings that actually represent different names. In this paper, we proposed an efficient algorithm for parallel AND computation. The proposed algorithm mainly addresses the load balancing issue across many computing nodes. It involves the following strategies:(1) Author-based load balancing, which splits the computation load for each core by author name labels. (2) Matrix-based strategy, which calculates the pairwise similarity between publications and saves them in a matrix globally shared by all processes. Then group them by width-first search. We combine the above two strategies, the second of which is used to calculate authors with a large number of documents, and the other authors apply the first. We constructed a publications database written by Chinese authors from MEDLINE, the biggest public database for biomedical literature (abstracts). For benchmark testing, we experimented our algorithm with a dataset of 1 million publications on the Tianhe-2A supercomputer. Firstly, we trained an AND classifier that can achieve 98.1% of F1. The serial computation time is estimated to be approximately 246 hours, while the parallel execution time is approximately 66 hours in the case of four cores on a single node (with a speedup of 3.7x). Finally, we reduced the total parallel computing time of 1 million documents to about 2 hours and achieved 65.8% of parallelism efficiency using 200 cores on 90 nodes. © 2019 IEEE.

关键词： Matrix algebra

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A modified low cycle fatigue Chaboche model for irradiation hardening behaviour of EUROFER97 at elevated temperatures

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European Journal of Mechanics - A/Solids 2025年 114卷

作者： Jianxin Liu Xiaowei Wang Aleksandr Zinovev Dmitry Terentyev Lihua Wang Magd Abdel Wahab Soete Laboratory Department of Electrical Energy Metals Mechanical Constructions and Systems Faculty of Engineering and Architecture Ghent University 9000 Ghent Belgium School of Mechanical and Power Engineering Nanjing Tech University Nanjing 211816 China Reliability Centered Manufacturing Research Institute Nanjing Tech University Nanjing 211816 China Structural Materials Group Institute for Nuclear Energy Technology Belgian Nuclear Research Centre SCK CEN 2400 Mol Belgium School of Aerospace Engineering and Applied Mechanics Tongji University Shanghai 200092 China Parallel and Distributed Systems Laboratory Jožef Stefan Institute Jamova cesta 39 SI-1000 Ljubljana Slovenia College of Engineering Yuan Ze University Taiwan Republic of China

This study investigates the irradiation hardening mechanical behaviour of EUROFER97, a Reduced Activation Ferritic/Martensitic (RAFM) steel, using a modified Chaboche model within the temperature range of 250–350 °C. Structural materials for nuclear fusion reactors must maintain their performance under neutron irradiation. However, EUROFER97 faces challenges such as irradiation-induced hardening and embrittlement at irradiation temperatures below 350 °C, which lead to reduced ductility and toughness. This research incorporates an irradiation hardening factor into a modified Chaboche constitutive model to accurately simulate EUROFER97's behaviour under irradiation. A unified viscoplastic model is employed for finite element analysis, with variable parameters used to better represent the material's stress-strain evolution during cyclic loading and irradiation-induced hardening. Simulations are conducted using ABAQUS, with a UMAT subroutine developed to simulate fatigue, and a hybrid acceleration strategy is adopted to accelerate the calculation of different stages of Low Cycle Fatigue (LCF). Key findings demonstrate that the modified Chaboche model effectively predicts the irradiation hardening and cyclic softening behaviour of EUROFER97 under various irradiation doses and strain amplitudes. The model's predictions are in good agreement with experimental data, capturing the stress-strain hysteresis loops and irradiation-induced changes in mechanical properties, thereby validating its applicability not only to EUROFER97 but also to other nuclear structural materials, such as F82H ferritic/martensitic steel. The contribution of this study lies in refining the Chaboche model by incorporating irradiation effects, providing a robust tool for predicting the mechanical behaviour of structural materials under irradiation, which is crucial for the safety and design of fusion reactor components.

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RBF-FD analysis of 2D time-domain acoustic wave propagation in heterogeneous media

arXiv

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arXiv 2020年

作者： Berljavac, Jure Močnik Mishra, Pankaj K. Slak, Jure Kosec, Gregor Faculty of Mathematics and Physics University of Ljubljana Jadranska 19 Ljubljana1000 Slovenia "Jožef Stefan" Institute Department E6 Parallel and Distributed Systems Laboratory Jamova cesta 39 Ljubljana1000 Slovenia Institute for Geophysics University of Texas at Austin 10100 Burnet Road AustinTX United States

Radial Basis Function-generated Finite Differences (RBF-FD) is a popular variant of local strong-form meshless methods that do not require a predefined connection between the nodes, making it easier to adapt node-distribution to the problem under consideration. This paper investigates an RBF-FD solution of time-domain acoustic wave propagation in the context of seismic modeling in the Earth’s subsurface. Through a number of numerical tests, ranging from homogeneous to highly-heterogeneous velocity models including non-smooth irregular topography, we demonstrate that the present approach can be further generalized to solve large-scale seismic modeling and full waveform inversion problems in arbitrarily complex models enabling more robust interpretations of geophysical observations. Copyright © 2020, The Authors. All rights reserved.

关键词： Radial basis function networks

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Performance of interpolating approximation schemes in MLPG meshless solver

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AIP Conference Proceedings 2020年第1期2293卷

作者： Roman Trobec Rituraj Singh 1“Jožef Stefan” Institute Parallel and Distributed Systems Laboratory Jamova cesta 39 1000 Ljubljana Slovenia

An interpolating moving least square (MLS) approximation was applied in the Meshless Petrov Galerkin method for a solution of Laplace equation. Accuracy and calculation complexity have been analyzed. Results show that original and interpolating MLS schemes are comparable in accuracy, with a small advantage for MLS. The interpolating MLS supports the direct imposition of essential boundary conditions, like in FEM.

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VButton: Practical attestation of user-driven operations in mobile apps 18

VButton: Practical attestation of user-driven operations in ...

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16th ACM International Conference on Mobile systems, Applications, and Services,MobiSys 2018

作者： Li, Wenhao Luo, Shiyu Sun, Zhichuang Xia, Yubin Lu, Long Chen, Haibo Zang, Binyu Guan, Haibing Institute of Parallel and Distributed Systems Shanghai Jiao Tong University China Shanghai Key Laboratory of Scalable Computing and Systems Shanghai Jiao Tong University China Northeastern University United States

ISBN: (纸本)9781450357203

More and more malicious apps and mobile rootkits are found to perform sensitive operations on behalf of legitimate users without their awareness. Malware does so by either forging user inputs or tricking users into making unintended requests to online service providers. Such malware is hard to detect and generates large revenues for cybercriminals, which is often used for committing ad/click frauds, faking reviews/ratings, promoting people or business on social networks, etc. We find that this class of malware is possible due to the lack of practical and robust means for service providers to verify the authenticity of user-driven operations (i.e., operations supposed to be performed, or explicitly confirmed, by a user). We design and build the VButton system to fill this void. Our system introduces a class of attestation-enabled app UI widgets (called VButton UI). Developers can easily integrate VButton UI in their apps to allow service providers to verify that a user-driven operation triggered by a VButton UI is indeed initiated and intended by a real user. Our system contains an on-device Manager, and a server-side Verifier. Leveraging ARM TrustZone, our system can attest operation authenticity even in the presence of a compromised OS. We have implemented the VButton system on an ARM development board as well as a commercial off-the-shelf smartphone. The evaluation results show that the system incurs negligible overhead. © 2018 Association for Computing Machinery.

关键词： Malware

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Radial basis function-generated finite differences solution of natural convection problem in 3D

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AIP Conference Proceedings 2020年第1期2293卷

作者： Gregor Kosec Jure Slak 1“Jožef Stefan” Institute E6 Parallel and Distributed Systems Laboratory Jamova cesta 39 1000 Ljubljana Slovenia

The goal of the paper is to present the complete meshless solution procedure, i.e. without meshing or using the regular nodes in any part of the solution procedure, for a thermo-fluid problem governed by Navier-Stokes and heat equations. The core of the solution procedure is an approximation of differential operators with Radial basis function-generated finite differences (RBF- FD) meshless method, iterative pressure-velocity coupling, and implicit time stepping. The flexibility of the presented solution procedure and its implementation is demonstrated by solving a natural convection problem in 2D and 3D irregular domains on scattered nodes. The results, presented in terms of maximal cross-section velocities, are compared against available published data, with good agreement achieved.

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On the parallels between Paxos and Raft, and how to port optimizations (Extended Version)

arXiv

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arXiv 2019年

作者： Wang, Zhaoguo Zhao, Changgeng Mu, Shuai Chen, Haibo Li, Jinyang Shanghai Key Laboratory of Scalable Computing and Systems Shanghai Jiao Tong University Institute of Parallel and Distributed Systems Shanghai Jiao Tong University Department of Computer Science New York University Department of Computer Science Stony Brook University

In recent years, Raft has overtaken Paxos as the consensus algorithm of choice. [53] While many have pointed out similarities between the two protocols, no one has formally mapped out their relationships. In this paper, we show how Raft and Paxos are formally related despite their surface differences. Based on the formal mapping between the two protocols, we show how to automatically port a certain class of optimizations from Paxos to Raft with guaranteed correctness. As case studies, we port and evaluate two optimizations, Mencius and Paxos Quorum Lease to Raft. Copyright © 2019, The Authors. All rights reserved.

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Refined RBF-FD Solution of Linear Elasticity Problem

Refined RBF-FD Solution of Linear Elasticity Problem

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International Multidisciplinary Conference on Computer and Energy Science (SpliTech)

作者： Jure Slak Gregor Kosec “Jozef Stefan” Institute Parallel and Distributed Systems Laboratory Ljubljana Slovenia

ISBN: (纸本)9781538662960

Solving PDEs with Radial Basis Functions, especially using local approaches, has become a promising alternative to the Finite Element Method. This paper describes one such approach, a local RBF-FD method, analogous to Finite Difference Method, that can handle irregular geometries, varying discretization densities and is easy to implement. RBF - FD method is analysed by solving basic linear elasticity problems using uniform and refined discretizations. Finally, a linear elasticity problem arising from analysis of fretting fatigue is solved and RBF - FD solution is compared to existing solutions, obtained using commercial software.

关键词： Shape Stress Boundary conditions Elasticity Fatigue Structural beams Loading

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JCDTA: The Data Trading Archtecture Design in JointCloud Computing 24

JCDTA: The Data Trading Archtecture Design in JointCloud Com...

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24th IEEE International Conference on parallel and distributed systems, ICPADS 2018

作者： Yue, Xikun Wang, Huaimin Liu, Wei Li, Wei Shi, Peichang Ouyang, Xue Science and Technology on Parallel and Distributed Laboratory National University of Defense Technology Changsha China Laboratory of Software Engineering for Complex Systems National University of Defense Technology Changsha China Troops No.75835 PLA China China

ISBN: (纸本)9781538673089

JointCloud computing is a new generation cloud computing model based on collaboration among Cloud Service Providers, making resources from multiple clouds deeply integrated., and supporting customize cloud service. To achieve the data confirmation Right when doing data trading to prevent resell is one of the most important challenges faced by such JointCloud environment. In this paper, we propose the JointCloud Computing Data Trading Architecture (JCDTA), an optimized data trading architecture for cross-stakeholder. Firstly, the announced mechanism is used to extract the data resources summary and the owner information into blockchain. Secondly, the untampering of the blockchain is used to record the data resources information, such as data resources statement information, data resources transaction records and data resources operation records. Finally, the supervision mechanism confirms the declaration of the data sources while the encryption technology ensures the privacy of the data resources. JCDTA guarantees the security and the reliability of data trading in the JointCloud environment and ensures the value invariance of data resources. © 2018 IEEE.

关键词： Blockchain

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