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Large-throughput parallel optical interconnection for a distributed parallel computing system

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Large-throughput parallel optical interconnection for a dist...

Pacific Rim Conference on Lasers and Electro-Optics (CLEO/Pacific Rim)

作者： S. Nishimura K. Harasawa N. Matsudairn S. Akutsu S. Sasaki T. Kudoh RWCP Optical Interconnection Hitachi Laboratory c/o Central Research Lab Hitachi and Limited Kokubunji Tokyo Japan Hitachi Communication Systems Inc. Yokohama Japan Parallel and Distributed System Architecture Laboratory RWCP Tsukuba Ibaraki Japan

We produced a large-throughput optical interconnection for a distributed parallel computing system. It transmits optical data at a rate of over 800-Mbit/s/spl times/10-bit through a 50-m single-mode fiber, using a CMO... 详细信息

关键词： Optical interconnections parallel processing Optical receivers High speed optical techniques Optical transmitters Optical network units Data communication Throughput Optical fiber networks Optical crosstalk

Fast variable density node generation on parametric surfaces with application to mesh-free methods

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arXiv 2020年

作者： Duh, Urban Kosec, Gregor Slak, Jure "Joef Stefan" Institute Department E6 Parallel and Distributed Systems Laboratory Jamova cesta 39 Ljubljana1000 Slovenia Faculty of Mathematics and Physics University of Ljubljana Jadranska 19 Ljubljana1000 Slovenia

Domain discretization is considered a dominant part of solution procedures for solving partial differential equations. It is widely accepted that mesh generation is among the most cumbersome parts of the FEM analysis and often requires human assistance, especially in complex 3D geometries. When using alternative mesh-free approaches, the problem of mesh generation is simplified to the problem of positioning nodes, a much simpler task, though still not trivial. In this paper we present an algorithm for generation of nodes on arbitrary d-dimensional surfaces. This algorithm complements a recently published algorithm for generation of nodes in domain interiors, and represents another step towards a fully automated dimension-independent solution procedure for solving partial differential equations. The proposed algorithm generates nodes with variable density on surfaces parameterized over arbitrary parametric domains in a dimension-independent way in O(N log N) time. It is also compared with existing algorithms for generation of surface nodes for mesh-free methods in terms of quality and execution *** Codes 65D99, 65N99, 65Y20, 68Q25 Copyright © 2020, The Authors. All rights reserved.

关键词： Mesh generation

Vision-Language Navigation: A Survey and Taxonomy

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arXiv 2021年

作者： Wu, Wansen Chang, Tao Li, Xinmeng Yin, Quanjun Zhu, Jiancheng The College of Systems Engineering National University of Defense Technology Hunan Changsha410073 China National Key Laboratory of Parallel and Distributed Processing College of Computer Science and Technology National University of Defence Technology Changsha410073 China

Vision-Language Navigation (VLN) tasks require an agent to follow human language instructions to navigate in previously unseen environments. This challenging field involving problems in natural language processing, computer vision, robotics, etc., has spawn many excellent works focusing on various VLN tasks. This paper provides a comprehensive survey and an insightful taxonomy of these tasks based on the different characteristics of language instructions in these tasks. Depending on whether the navigation instructions are given for once or multiple times, this paper divides the tasks into two categories, i.e., single-turn and multi-turn tasks. For single-turn tasks, we further subdivide them into goal-oriented and route-oriented based on whether the instructions designate a single goal location or specify a sequence of multiple locations. For multi-turn tasks, we subdivide them into passive and interactive tasks based on whether the agent is allowed to question the instruction or not. These tasks require different capabilities of the agent and entail various model designs. We identify progress made on the tasks and look into the limitations of existing VLN models and task settings. Finally, we discuss several open issues of VLN and point out some opportunities in the future, i.e., incorporating knowledge with VLN models and implementing them in the real physical world. © 2021, CC BY.

关键词： Taxonomies

Meshless Interface Tracking for the Simulation of Dendrite Envelope Growth

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SSRN

SSRN 2023年

作者： Jančič, Mitja Založnik, Miha Kosec, Gregor Institute Jožef Stefan Parallel and Distributed Systems Laboratory Jamova cesta 39 Ljubljana1000 Slovenia Universite de Lorraine CNRS IJL NancyF-54000 France Laboratory of Excellence DAMAS Universite de Lorraine Nancy/Metz France

The growth of dendritic grains during solidification is often modelled using the Grain Envelope Model (GEM), in which the envelope of the dendrite is an interface tracked by the Phase Field Interface Capturing (PFIC) method. In the PFIC method, an phase-field equation is solved on a fixed mesh to track the position of the envelope. While being versatile and robust, PFIC introduces certain numerical artefacts. In this work, we present an alternative approach for the solution of the GEM that employs a Meshless (sharp) Interface Tracking (MIT) formulation, which uses direct, artefact-free interface tracking. In the MIT, the envelope (interface) is defined as a moving domain boundary and the interface-tracking nodes are boundary nodes for the diffusion problem solved in the domain. To increase the accuracy of the method for the diffusion-controlled moving-boundary problem, an [[EQUATION]] -adaptive spatial discretization is used, thus, the node spacing is refined in the vicinity of the envelope. MIT combines a parametric surface reconstruction, a mesh-free discretization of the parametric surfaces and the space enclosed by them, and a high-order approximation of the partial differential operators and of the solute concentration field using radial basis functions augmented with monomials. The proposed method is demonstrated on a two-dimensional [[EQUATION]] -adaptive solution of the diffusive growth of dendrite and evaluated by comparing the results to the PFIC approach. It is shown that MIT can reproduce the results calculated with PFIC, that it is convergent and that it can capture more details in the envelope shape than PFIC with a similar spatial discretization. © 2023, The Authors. All rights reserved.

关键词： Surface reconstruction

Meshless interface tracking for the simulation of dendrite envelope growth

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arXiv 2023年

作者： Jančič, Mitja Založnik, Miha Kosec, Gregor Institute Jožef Stefan Parallel and Distributed Systems Laboratory Jamova cesta 39 Ljubljana1000 Slovenia Université de Lorraine CNRS IJL NancyF-54000 France Laboratory of Excellence DAMAS Université de Lorraine Metz Nancy France

The growth of dendritic grains during solidification is often modelled using the Grain Envelope Model (GEM), in which the envelope of the dendrite is an interface tracked by the Phase Field Interface Capturing (PFIC) method. In the PFIC method, an phase-field equation is solved on a fixed mesh to track the position of the envelope. While being versatile and robust, PFIC introduces certain numerical artefacts. In this work, we present an alternative approach for the solution of the GEM that employs a Meshless (sharp) Interface Tracking (MIT) formulation, which uses direct, artefact-free interface tracking. In the MIT, the envelope (interface) is defined as a moving domain boundary and the interface-tracking nodes are boundary nodes for the diffusion problem solved in the domain. To increase the accuracy of the method for the diffusion-controlled moving-boundary problem, an h-adaptive spatial discretization is used, thus, the node spacing is refined in the vicinity of the envelope. MIT combines a parametric surface reconstruction, a mesh-free discretization of the parametric surfaces and the space enclosed by them, and a high-order approximation of the partial differential operators and of the solute concentration field using radial basis functions augmented with monomials. The proposed method is demonstrated on a two-dimensional h-adaptive solution of the diffusive growth of dendrite and evaluated by comparing the results to the PFIC approach. It is shown that MIT can reproduce the results calculated with PFIC, that it is convergent and that it can capture more details in the envelope shape than PFIC with a similar spatial discretization. © 2023, CC0.

关键词： Surface reconstruction

Adaptive Radial Basis Function-generated Finite Differences method for contact problems

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arXiv 2018年

作者： Slak, Jure Kosec, Gregor Department E6 "Jožef Stefan" Institu Jamova ulica 39 Ljubljana1000 Slovenia Parallel and Distributed Systems Laboratory "Jožef Stefan" Institute Slovenia Faculty of Mathematics and Physics University of Ljubljana Slovenia

This paper proposes an original adaptive refinement framework using Radial Basis Functions-generated Finite Differences method. Node distributions are generated with a Poisson Disk Sampling-based algorithm from a given continuous density function, which is altered during the refinement process based on the error indicator. All elements of the proposed adaptive strategy rely only on meshless concepts, which leads to great flexibility and generality of the solution procedure. The proposed framework is tested on four gradually more complex contact problems, governed by the Cauchy-Navier equations. First, a disk under pressure is considered and the computed stress field is compared to the closed form solution of the problem to assess the basic behaviour of the algorithm and the influence of free parameters. Second, a Hertzian contact problem, also with known closed form solution, is studied to analyse the proposed algorithm with an ad-hoc error indicator and to test both refinement and derefinement. A contact problem, typical for fretting fatigue, with no known closed form solution is considered and solved next. It is demonstrated that the proposed methodology can be used in practical application and produces results comparable with FEM without the need for manual refinement or any human intervention. In the last case, generality of the proposed approach is demonstrated by solving a 3-D Boussinesq’s problem of the concentrated normal traction acting on an isotropic *** Codes 65N65, 74B05 Copyright © 2018, The Authors. All rights reserved.

关键词： Radial basis function networks

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Matching matchings

Matching matchings

Eastern European Regional Conference on the Engineering of Computer Based systems

作者： Gábor Bacsó Anita Keszler Zsolt Tuza Laboratory of Parallel and Distributed Systems MTA SZTAKI Distributed Events Analysis Research Group MTA SZTAKI Rényi Institute Budapest

ISBN: (纸本)9781479908530

This paper presents the first steps toward a graph comparison method based on matching matchings, or in other words, comparison of independent edge sets in graphs. The novelty of our approach is to use matchings for calculating distance of graphs in case of edge-colored graphs. This idea can be used as a preprocessing step of graph querying applications, to speed up exact and inexact graph matching methods. We introduce the notion of colored matchings and prove some properties of them in edge colored complete graphs and complete bipartite graphs in case of two colors.

关键词： edge-colored graph inexact graph matching colored matching

Orthogonal Nonnegative Locally Linear Embedding

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Orthogonal Nonnegative Locally Linear Embedding

IEEE International Conference on systems, Man, and Cybernetics

作者： Lei Wei Naiyang Guan Xiang Zhang Zhigang Luo Dacheng Tao National Laboratory for Parallel and Distributed Processing School of Computer Science National University of Defense Technology Changsha 410073 P.R. China These authors contributed equally to this paper National Laboratory for Parallel and Distributed Processing School of Computer Science National University of Defense Technology Changsha 410073 P.R. China Centre for Quantum Computation and Intelligence Systems and Faculty of Engineering and Information Technology University of Technology Sydney Sydney NSW 2007 Australia

ISBN: (纸本)9781479906505

Nonnegative matrix factorization (NMF) decomposes a nonnegative dataset X into two low-rank nonnegative factor matrices, i.e., W and H, by minimizing either Kullback-Leibler (KL) divergence or Euclidean distance between X and WH. NMF has been widely used in pattern recognition, data mining and computer vision because the non-negativity constraints on both W and H usually yield intuitive parts-based representation. However, NMF suffers from two problems: 1) it ignores geometric structure of dataset, and 2) it does not explicitly guarantee partsbased representation on any datasets. In this paper, we propose an orthogonal nonnegative locally linear embedding (ONLLE) method to overcome aforementioned problems. ONLLE assumes that each example embeds in its nearest neighbors and keeps such relationship in the learned subspace to preserve geometric structure of a dataset. For the purpose of learning parts-based representation, ONLLE explicitly incorporates an orthogonality constraint on the learned basis to keep its spatial locality. To optimize ONLLE, we applied an efficient fast gradient descent (FGD) method on Stiefel manifold which accelerates the popular multiplicative update rule (MUR). The experimental results on real-world datasets show that FGD converges much faster than MUR. To evaluate the effectiveness of ONLLE, we conduct both face recognition and image clustering on real-world datasets by comparing with the representative NMF methods.

关键词： Nonnegative matrix factorization Locally linear embedding Fast gradient descent Stiefel manifold Dataset Nonnegative matrix decomposition geometrical construction NMF protocol images embedding Flue gas desulfurization Nearest neighbor Orthogonal

Eunomia: Scaling Concurrent Search Trees under Contention Using HTM

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ACM SIGPLAN Notices 2017年第8期52卷 385-399页

作者： Wang, Xin Zhang, Weihua Wang, Zhaoguo Wei, Ziyun Chen, Haibo Zhao, Wenyun Software School Fudan University China Shanghai Key Laboratory of Data Science Fudan University School of Computer Science Fudan University China Institute of Parallel and Distributed Systems Shanghai Jiao Tong University China Computer Science Department New York University United States

While hardware transactional memory (HTM) has recently been adopted to construct efficient concurrent search tree structures, such designs fail to deliver scalable performance under contention. In this paper, we first conduct a detailed analysis on an HTM-based concurrent B+Tree, which uncovers several reasons for excessive HTM aborts induced by both false and true conflicts under contention. Based on the analysis, we advocate Eunomia, a design pattern for search trees which contains several principles to reduce HTM aborts, including splitting HTM regions with version-based concurrency control to reduce HTM working sets, partitioned data layout to reduce false conflicts, proactively detecting and avoiding true conflicts, and adaptive concurrency control. To validate their effectiveness, we apply such designs to construct a scalable concurrent B+Tree using HTM. Evaluation using key-value store benchmarks on a 20-core HTM-capable multi-core machine shows that Eunomia leads to 5X-11X speedup under high contention, while incurring small overhead under low contention. © 2017 ACM.

关键词： Concurrency control