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Proximity-based service discovery for distributed digital twin systems

Discover Internet of Things 2025年第1期5卷 1-24页

作者： Rothermel, Kurt Herzog, Otthein Zhiqiang, Siegfried Wu Institute Of Parallel and Distributed Systems University of Stuttgart Universitaetsstr. 38 Stuttgart70569 Germany College of Architecture and Urban Planning Tongji University 1239 Siping Road Shanghai200092 China Department of Mathematics and Computer Science University of Bremen Bibliothekstrasse 5 Bremen23884 Germany

Over the past decade, there has been a significant increase in interest in digital twin (DT) technology in a variety of domains. While research on DTs of single assets was initially prevalent, there has been a notable shift towards distributed systems of DTs, which connect to each other to collaborate. Typically, collaboration is enabled by DTs providing services that can be consumed by other DTs. In service-oriented systems, a service is typically identified by type information. However, this is not sufficient in distributed DT systems, where DTs associated with different physical entities may provide the same type of service. Consequently, selecting the appropriate service depends not only on the service type, but also on the associated physical entity. However, requiring DTs to know the mapping of services to their physical environment is not feasible for large dynamic systems. This paper presents a novel proximity-based service discovery method that allows DTs to select services based on service type and their proximity to other objects. That is, service specifications are fully abstracted from the mapping of services to physical objects, relieving DTs from maintaining information about this mapping. Furthermore, service discovery is robust to changes in the physical environment and service population. The proposed service discovery method has been implemented on top of a spatial DBMS. We argue that this implementation is optimal in terms of network utilization and latency, and perform comprehensive evaluations to show the performance of discovery queries as a function of their complexity. © The Author(s) 2025.

关键词： Location based services

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Telemetry for Quantum systems in HPC Centers

Telemetry for Quantum Systems in HPC Centers

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ISC High Performance 2025 Research Paper Proceedings (40th International Conference)

作者： Hossam Ahmed Burak Mete Helmut Heller Matthew Tovey Xiaolong Deng Asim Zulfiqar Muhammad Nufail Farooqi Mahmoud Abuzayed Martin Schulz Laura Schulz QCT Department Leibniz Supercomputing Centre of the Bavarian Academy of Science and Humanities (LRZ) Garching b. München Germany Chair for Computer Architecture and Parallel Systems (CAPS) Technical University of Munich (TUM) Garching b. München Germany

ISBN: (数字)9783982633619

Quantum systems have traditionally operated within highly controlled laboratory environments to minimize internal noise and maximize stability. However, when these systems are integrated into High Performance Computing (HPC) environments and setup for continuous operation, they encounter significantly higher levels of external noise and instability coupled with higher demands. This paper introduces a comprehensive framework to counter the challenges of maintaining the stability of operational quantum computers in such noisy HPC settings. We propose a novel system architecture that monitors and manages the environmental conditions of quantum computing systems using a broad set of sensors, enhancing their robustness and reliability. Our architecture is open and can be extended to other setups. It can serve as a blueprint for other sites as it spans quantum technologies and offers broad coverage. Ultimately, this data will be essential to facilitate advancements in machine learning to drive real-time error mitigation.

关键词： computers Quantum system Trapped ions Quantum computing Working environment noise systems architecture Machine learning Stability analysis Telemetry Monitoring

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DIPOLAR UNIT SIZE IN COUPLED-DIPOLE CALCULATIONS OF THE SCATTERING MATRIX-ELEMENTS

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OPTICS LETTERS 1993年第15期18卷 1211-1213页

作者： HOEKSTRA, AG SLOOT, PMA Parallel Scientific Computing Group department of Computer Systems Faculty of Mathematics and Computer Science University of Amsterdam

The coupled-dipole method is widely used to calculate the light-scattering matrix S from arbitrary particles. An important parameter in the model is the size of the dipolar subunits. Usually a size of approximately 1/10 to approximately 1/20 of the wavelength of the incident light is sufficient for accurate calculations. However, it was noted that accurate S-34 calculations require much smaller dipolar subunits. We show that this conclusion is too pessimistic, by examining the sensitivity of the S-34 elements on surface roughness of spherical particles. Furthermore we give an example of an accurate S-34 calculation with dipolar subunits as large as 1/10 of the wavelength.

关键词： .dipoles surface roughness CD method Coupled Dipole Scattering Matrix dipolar subunits

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e-science and the VL-e approach

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1st Converging science conference, 2004

作者： Bob Hertzberger, L.O. Computer Architecture and Parallel Systems Group Department of Computer Science Universiteit van Amsterdam Netherlands

ISBN: (纸本)9783540332459

Now that the Internet and Web are abundantly present in every days live and net-working and computing speed are improving at an impressive rate, more and more attempts become visible to apply these developments towards science, in general often called: e-science. In order for e-science to work, an environment has to be created that should support the requirements of different scientific domains such as life sciences or high energy physics research. © Springer-Verlag Berlin Heidelberg 2006.

关键词： e-science

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Efficient Evolution of Variable Ordering for Binary Decision Diagram Optimization

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IEEE Transactions on Evolutionary Computation 2025年

作者： Krauss, Rune Drechsler, Rolf German Research Center for Artificial Intelligence Cyber-Physical Systems Department Bremen28359 Germany University of Bremen Group of Computer Architecture Institute of Computer Science Bremen28359 Germany

The hardware complexity related to the number of transistors in electronic devices used by today's society has grown considerably in the last decades because of technological progress. In order to guarantee the correct behavior of such devices and meet time-to-market constraints, there is a need to continuously develop more efficient data structures and algorithms in formal verification. The performance of verification algorithms depends in particular on the compactness of data structures. A reduced ordered binary decision diagram (BDD) is basically a suitable data structure to verify digital circuits, as it represents Boolean functions canonically respecting a variable ordering and allows direct manipulation of them. However, one of the main challenges with BDDs is to find a variable ordering so that the BDD size of a function is compact and does not become impractical due to a dramatically increasing number of BDD nodes. To address the aforementioned issue, this article presents a novel evolution strategy having an efficient evaluation of variable ordering in a divide-and-conquer manner for BDD optimization. Experiments on benchmarks of multilevel circuits show that using this strategy results in considerably smaller BDDs being found significantly faster compared to state-of-the-art optimization techniques. © 1997-2012 IEEE.

关键词： Evolutionary algorithms

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A high performance distributed database system for enhanced internet services

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International Conference and Exhibition on High-Performance Computing and Networking, HPCN 1998

作者： Peddemors, A. Hertzberger, L.O. University of Amsterdam Department of Computer Science Computer Architecture and Parallel Systems Group Kruislaan 403 1098 SJ Amsterdam Netherlands

ISBN: (纸本)3540644431

Using a distributed database system as part of a distributed web server architecture has obvious advantages. It is shown that a first phase distributed database system can be build by extending an existing object oriented database system with application specific additions. A web database is implemented, as part of a traditional HTTP based distributed web server, using this distributed database system. © Springer-Verlag Berlin Heidelberg 1998.

关键词： Distributed database systems

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A hierarchical particle swarm optimizer for noisy and dynamic environments

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Genetic Programming and Evolvable Machines 2006年第4期7卷 329-354页

作者： Janson, Stefan Middendorf, Martin Parallel Computing and Complex Systems Group Department of Computer Science University of Leipzig Augustusplatz 10/11 D-04109 Leipzig Germany

New Particle Swarm Optimization (PSO) methods for dynamic and noisy function optimization are studied in this paper. The new methods are based on the hierarchical PSO (H-PSO) and a new type of H-PSO algorithm, called Partitioned Hierarchical PSO (PH-PSO). PH-PSO maintains a hierarchy of particles that is partitioned into several sub-swarms for a limited number of generations after a change of the environment occurred. Different methods for determining the best time when to rejoin the sub-swarms and how to handle the topmost sub-swarm are discussed. A standard method for metaheuristics to cope with noise is to use function re-evaluations. To reduce the number of necessary re-evaluations a new method is proposed here which uses the hierarchy to find a subset of particles for which re-evaluations are particularly important. In addition, a new method to detect changes of the optimization function in the presence of noise is presented. It differs from conventional detection methods because it does not require additional function evaluations. Instead it relies on observations of changes that occur within the swarm hierarchy. The new algorithms are compared experimentally on different dynamic and noisy benchmark functions with a variant of standard PSO and H-PSO that are both provided with a change detection and response method. © Springer science+Business Media, LLC 2006.

关键词： Computational methods

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Design issues for high performance simulation

Design issues for high performance simulation

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作者： Sloot, P.M.A. Pimentel, A.D. Hertzberger, L.O. Parallel Scientific Computing and Simulation Group Department of Computer Science University of Amsterdam Kruislaan 403 1098 SJ Amsterdam Netherlands Computer Architecture and Parallel Systems Group Department of Computer Science University of Amsterdam Kruislaan 403 1098 SJ Amsterdam Netherlands

One of the key issues in designing new simulation models for parallel execution, or in the migration of existing models to parallel platforms, is the mapping of the application architecture to the parallel system architecture. In this mapping process, we can easily loose track of the inherent locality present in the different architecture layers. In this paper, we present an overview of these issues and examine, by means of several case-studies, the consequences of the design and implementation choices for the various mapping processes. We will show that the potential for high performance simulation comes from a holistic approach, taking into account all aspects from the application to the underlying hardware. © 1998 Elsevier science B. V. All rights reserved.

关键词： parallel processing systems

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Public and private BitTorrent communities: A measurement study 9

Public and private BitTorrent communities: A measurement stu...

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9th International Workshop on Peer-to-Peer systems, IPTPS 2010

作者： Meulpolder, M. D'Acunto, L. Capotă, M. Wojciechowski, M. Pouwelse, J.A. Epema, D.H.J. Sips, H.J. Parallel and Distributed Systems Group Department of Computer Science Delft University of Technology Netherlands

BitTorrent communities, both public and private, are immensely popular in the Internet, with tens of millions of users simultaneously active at any given moment. Public and private BitTorrent communities are managed in different ways - for instance, some private communities enforce sharing ratios, have strict rules for content management, have a certain level of community oversight, and maintain a strong sense of exclusiveness. In this paper, we present the results of extensive measurements of more than half a million peers in five communities, ranging from highly popular and well-known public communities to elite private communities that can only be joined by invitation. We observe that the performance experienced by downloaders in the private communities is by far superior to the performance in the public communities, and we observe significant differences in connectability, seeder/leecher ratio, and seeding duration. Based on our results, we conjecture that when effective ratio enforcement mechanisms are in place, BitTorrent's tit-for-tat mechanism is hardly influential anymore. Our multi-community, multi-swarm measurements are significantly broader and more extensive than any earlier measurement study on BitTorrent. © IPTPS *** right reserved.

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Improving accuracy and coverage in an internet-deployed reputation mechanism

Improving accuracy and coverage in an internet-deployed repu...

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2010 IEEE 10th International Conference on Peer-to-Peer Computing, P2P 2010

作者： Delaviz, Rahim Andrade, Nazareno Pouwelse, Johan A. Parallel and Distributed Systems Group Department of Computer Science Delft University of Technology Netherlands

ISBN: (纸本)9781424471416

P2P systems can benefit from reputation mechanisms to promote cooperation and help peers to identify good service providers. However, in spite of a large number of proposed reputation mechanisms, few have been investigated in real situations. BarterCast is a distributed reputation mechanism used by our Internet-deployed Bittorent-based file-sharing client Tribler. In BarterCast, each peer uses messages received from other peers to build a weighted, directed subjective graph that represents the upload and download activity in the system. A peer calculates the reputations of other peers by applying the maxflow algorithm to its subjective graph. For efficiency reasons, only paths of at most two hops are considered in this calculation. In this paper, we identify and assess three potential modifications to BarterCast for improving its accuracy and coverage (fraction of peers for which a reputation value can be computed). First, a peer executes maxflow from the perspective of the node with the highest betweenness centrality in its subjective graph instead of itself. Second, we assume a gossiping protocol that gives each peer complete information about upload and download activities in the system, and third, we lift the path length restriction in the maxflow algorithm. To assess these modifications, we crawl the Tribler network and collect the upload and download actions of the peers for three months. We apply BarterCast with and without the modifications on the collected data and measure accuracy and coverage. ©2010 IEEE.

关键词： Peer to peer networks

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