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IEEE International Conference on Communication Workshop, ICCW 2015

作者： Nguyen, Dang Khoa Matthaiou, Michail Duong, Trung Q. Ochi, Hiroshi Graduate School of Computer Science and Systems Engineering Kyushu Institute of Technology Fukuoka Japan School of Electronics Electrical Engineering and Computer Science Queen's University Belfast Belfast United Kingdom Department of Signals and Systems Chalmers University of Technology Gothenburg Sweden

ISBN: (纸本)9781467363051

This paper analyzes the impact of transceiver impairments on outage probability (OP) and throughput of decode-and-forward two-way cognitive relay (TWCR) networks, where the relay is self-powered by harvesting energy from the transmitted signals. We consider two bidirectional relaying protocols namely, multiple access broadcast (MABC) protocol and time division broadcast (TDBC) protocol, as well as, two power transfer policies namely, dual-source (DS) energy transfer and single-fixed-source (SFS) energy transfer. Closed-form expressions for OP and throughput of the network are derived in the context of delay-limited transmission. Numerical results corroborate our analysis, thereby we can quantify the degradation of OP and throughput of TWCR networks due to transceiver hardware impairments. Under the specific parameters, our results indicate that the MABC protocol achieves asymptotically a higher throughput by 0.65 [bits/s/Hz] than the TDBC protocol, while the DS energy transfer scheme offers better performance than the SFS policy for both relaying protocols. © 2015 IEEE.

关键词： Energy transfer

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Studying the Relation between Anti-Patterns in Design Models and in Source Code

Studying the Relation between Anti-Patterns in Design Models...

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IEEE International Conference on Software Analysis, Evolution and Reengineering (SANER)

作者： Bilal Karasneh Michel R. V. Chaudron Foutse Khomh Yann-Gael Gueheneuc LIACS Leiden Institute of Advanced CS Leiden Netherlands Computer Science and Engineering Chalmers University of Technology Göteborg Sweden Génie Informatique et Génie Logiciel Ecole Polytechnique de Montréal Montréal Canada

There exists a large body of work on the specification and detection of anti-patterns in the source code of software systems. However, there are very few studies on the origins of the occurrences of anti-patterns in the source code: do the very design of the systems lead to the occurrences of anti-patterns or are anti-patterns introduced during implementation? Knowing when anti-patterns are introduced could help software designers and developers improve the quality of the source code, for example by eliminating fault-prone anti-patterns early during the design of the systems, even before their implementation. Therefore, we detect occurrences of anti-patterns in design models and in the source code of some systems, trace these occurrences between design and implementation, and study their relation and impact on the source code. First, we analyze both the UML design models and the source code of 10 open-source systems and show that antipatterns exist in design models. We observe that, on average, 37% of the classes in the design models that belong to anti-patterns also exist in the source code and also play roles in the same anti-patterns. Second, we investigate two open-source systems to assess the impact of the anti-patterns in their design models on the source code in terms of changes and faults. We show that classes that have anti-patterns in the design models have more changes and faults in the source code. Our results suggest that the design of the systems lead to anti-patterns and that the antipatterns impact negatively the change-and fault-proneness of the classes in the source code. Thus, designers should be wary of anti-patterns in their design models and could benefit from tools that detect and trace these anti-patterns into the source code.

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The lock-free k-LSM relaxed priority queue 2015

The lock-free k-LSM relaxed priority queue

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20th ACM SIGPLAN Symposium on Principles and Practice of Parallel Programming, PPoPP 2015

作者： Wimmer, Martin Gruber, Jakob Träff, Jesper Larsson Tsigas, Philippas Faculty of Informatics Parallel Computing Vienna University of Technology Vienna/Wien1040 Austria Computer Science and Engineering Chalmers University of Technology Göteborg412 96 Sweden

ISBN: (纸本)9781450332057

We present a new, concurrent, lock-free priority queue that relaxes the delete-min operation to allow deletion of any of the ρ+1 smallest keys instead of only a minimal one, where ρ is a parameter that can be configured at runtime. It is built from a logarithmic number of sorted arrays, similar to log-structured merge-trees (LSM). For keys added and removed by the same thread the behavior is identical to a non-relaxed priority queue. We compare to state-of-the-art lock-free priority queues with both relaxed and non-relaxed semantics, showing high performance and good scalability of our approach.

关键词： Parallel programming

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Dispersion compensation filter design optimized for robustness and power efficiency

Dispersion compensation filter design optimized for robustne...

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Signal Processing in Photonic Communications, SPPCom 2015

作者： Sheikh, Alireza Fougstedt, Christoffer Graell i Amat, Alexandre Johannisson, Pontus Larsson-Edefors, Per Karlsson, Magnus Dept. of Signals and Systems Chalmers University of Technology GöteborgSE-412 96 Sweden Dept. of Computer Science and Engineering Chalmers University of Technology GöteborgSE-412 96 Sweden Photonics Laboratory Chalmers University of Technology GöteborgSE-412 96 Sweden

We present an optimized CD compensation filter with improved performance and increased resilience to quantization errors. The filter is given in closed form based on a constrained least-squares problem. © 2015 OSA.

ISBN: (纸本)9781557520005

关键词： Bandpass filters

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Power-efficient time-domain dispersion compensation using optimized FIR filter implementation

Power-efficient time-domain dispersion compensation using op...

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Signal Processing in Photonic Communications, SPPCom 2015

作者： Fougstedt, Christoffer Sheikh, Alireza Johannisson, Pontus Graell i Amat, Alexandre Larsson-Edefors, Per Dept. of Computer Science and Engineering Chalmers University of Technology GöteborgSE-412 96 Sweden Dept. of Signals and Systems Chalmers University of Technology GöteborgSE-412 96 Sweden Photonics Laboratory Chalmers University of Technology GöteborgSE-412 96 Sweden

We investigate fixed-point aspects and time-domain ASIC implementations of CD compensation. An optimized implementation gives significant power dissipation reduction for short links, with further reduction if pulse sh... 详细信息

ISBN: (纸本)9781557520005

关键词： Bandpass filters

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Quality assessment of UML class diagrams - A study comparing experts and students -

Quality assessment of UML class diagrams - A study comparing...

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MODELS Educators Symposium 2015, EduSymp 2015

作者： Karasneh, Bilal Stikkolorum, Dave R. Larios, Enrique Chaudron, Michel R.V. Leiden Institute of Advanced Computer Science Leiden University Leiden Netherlands Joint Dept. of Computer Science and Engineering Chalmers Univ. of Technology Gothenburg Univ. S-Gothenburg Sweden

In this paper, we present an experiment conducted for comparing how experts and students assess the quality of class diagrams. Six quality attributes were addressed: Understandability, Layout, Extensibility, Modifiability, Completeness and Correctness. From this study, we aim to find out how well students are capable of evaluating the quality of UML designs. Moreover, we aim to learn which features experts and students use for assessing the quality attrib-utes of class diagrams. The study reveals that experts and students' assessment of the six quality attributes differ significantly. However, a qualitative analysis of experts and students' feedback suggests that students use similar features as experts use for assessing the quality of diagrams. Hence peer-feedback from stu-dents can be useful in educational settings. © Copyright 2015 for the individual papers by the papers' authors.

关键词： Students

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Neural context embeddings for automatic discovery of word senses 1

Neural context embeddings for automatic discovery of word se...

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1st Workshop on Vector Space Modeling for Natural Language Processing, VS 2015 at the Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies, NAACL-HLT 2015

作者： Kågebäck, Mikael Johansson, Fredrik Johansson, Richard Dubhashi, Devdatt Computer Science and Engineering Chalmers University of Technology GöteborgSE-412 96 Sweden Språkbanken University of Gothenburg Box 200 Göteborg Sweden

ISBN: (纸本)9781941643464

Word sense induction (WSI) is the problem of automatically building an inventory of senses for a set of target words using only a text corpus. We introduce a new method for embedding word instances and their context, for use in WSI. The method, Instance-context embedding (ICE), leverages neural word embeddings, and the correlation statistics they capture, to compute high quality embeddings of word contexts. In WSI, these context embeddings are clustered to find the word senses present in the text. ICE is based on a novel method for combining word embeddings using continuous Skip-gram, based on both semantic and a temporal aspects of context words. ICE is evaluated both in a new system, and in an extension to a previous system for WSI. In both cases, we surpass previous state-of-the-art, on the WSI task of SemEval-2013, which highlights the generality of ICE. Our proposed system achieves a 33% relative improvement. © 2015 The North American Chapter of the Association for Computational Linguistics.

关键词： Ice

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First M87 event horizon telescope results. I. The shadow of the supermassive black hole

arXiv

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arXiv 2019年

作者： Akiyama, Kazunori Alberdi, Antxon Alef, Walter Asada, Keiichi Azulay, Rebecca Baczko, Anne-Kathrin Ball, David Baloković, Mislav Barrett, John Bintley, Dan Blackburn, Lindy Boland, Wilfred Bouman, Katherine L. Bower, Geoffrey C. Bremer, Michael Brinkerink, Christiaan D. Brissenden, Roger Britzen, Silke Broderick, Avery E. Broguiere, Dominique Bronzwaer, Thomas Byun, Do-Young Carlstrom, John E. Chael, Andrew Chan, Chi-kwan Chatterjee, Shami Chatterjee, Koushik Chen, Ming-Tang Chen, Yongjun Cho, Ilje Christian, Pierre Conway, John E. Cordes, James M. Crew, Geoffrey B. Cui, Yuzhu Davelaar, Jordy de Laurentis, Mariafelicia Deane, Roger Dempsey, Jessica Desvignes, Gregory Dexter, Jason Doeleman, Sheperd S. Eatough, Ralph P. Falcke, Heino Fish, Vincent L. Fomalont, Ed Fraga-Encinas, Raquel Freeman, William T. Friberg, Per Fromm, Christian M. Gómez, José L. Galison, Peter Gammie, Charles F. García, Roberto Gentaz, Olivier Georgiev, Boris Goddi, Ciriaco Gold, Roman Gu, Minfeng Gurwell, Mark Hada, Kazuhiro Hecht, Michael H. Hesper, Ronald Ho, Luis C. Ho, Paul Honma, Mareki Huang, Chih-Wei L. Huang, Lei Hughes, David H. Ikeda, Shiro Inoue, Makoto Issaoun, Sara James, David J. Jannuzi, Buell T. Janssen, Michael Jeter, Britton Jiang, Wu Johnson, Michael D. Jorstad, Svetlana Jung, Taehyun Karami, Mansour Karuppusamy, Ramesh Kawashima, Tomohisa Keating, Garrett K. Kettenis, Mark Kim, Jae-Young Kim, Junhan Kim, Jongsoo Kino, Motoki Koay, Jun Yi Koch, Patrick M. Koyama, Shoko Kramer, Michael Kramer, Carsten Krichbaum, Thomas P. Kuo, Cheng-Yu Lauer, Tod R. Lee, Sang-Sung Li, Yan-Rong Li, Zhiyuan Lindqvist, Michael Liu, Kuo Liuzzo, Elisabetta Lo, Wen-Ping Lobanov, Andrei P. Loinard, Laurent Lonsdale, Colin Lu, Ru-Sen National Radio Astronomy Observatory 520 Edgemont Road CharlottesvilleVA22903 United States Massachusetts Institute of Technology Haystack Observatory 99 Millstone Road WestfordMA01886 United States National Astronomical Observator of Ja an 2-21-1 Osawa Mitaka Tok o Ja an181-8588 Japan Black Hole Initiative at Harvard Universit 20 Garden Street Cambrid eMA02138 United States Instituto de Astrofísica de Andalucía-CSIC Glorieta de la Astronomía s/n GranadaE-18008 Spain Max-Planck-Institut für Radioastronomie Auf dem Hügel 69 BonnD-53121 Germany Institute of Astronomy and Astrophysics Academia Sinica 11F of Astronomy-Mathematics Building AS/NTU No. 1 Sec. 4 Roosevelt Rd Taipei10617 Taiwan Departament d’Astronomia i Astrofísica Universitat de València C. Dr. Moliner 50 Burjassot ValènciaE-46100 Spain Observatori Astronòmic Universitat de València C. Catedrático José Beltrán 2 Paterna ValènciaE-46980 Spain Steward Observatory Department of Astronomy University of Arizona 933 N. Cherry Ave TucsonAZ85721 United States Center for Astrophysics Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United States East Asian Observatory 660 N. A’ohoku Pl. HiloHI96720 United States PO Box 9513 Leiden2300 RA Netherlands California Institute of Technolo 1200 East California Boulevard PasadenaCA91125 United States Institute of Astronom Astro h sics Academia Sinica 645 N A’ohoku Place HiloHI96720 United States Institut de Radioastronomie Millimétri ue 300 rue de la Piscine Saint Martin d’HèresF-38406 France Radboud University P.O. Box 9010 Nijmegen6500 GL Netherlands Perimeter Institute for Theoretical Ph sics 31 Caroline Street North WaterlooONN2L 2Y5 Canada De artment of Ph sics Universit of Waterloo 200 Universit Avenue West WaterlooONN2L 3G1 Canada Waterloo Centre for Astrophysics University of Waterloo WaterlooONN2L 3G1 Canada Korea Astronomy and Space Science Institute Daedeok-daero 776 Yuseong-gu Daejeon34055 Korea

When surrounded by a transparent emission region, black holes are expected to reveal a dark shadow caused by gravitational light bending and photon capture at the event horizon. To image and study this phenomenon, we have assembled the Event Horizon Telescope, a global very long baseline interferometry array observing at a wavelength of 1.3 mm. This allows us to reconstruct event-horizon-scale images of the supermassive black hole candidate in the center of the giant elliptical galaxy M87. We have resolved the central compact radio source as an asymmetric bright emission ring with a diameter of 42 ± 3 μas, which is circular and encompasses a central depression in brightness with a flux ratio 10:1. The emission ring is recovered using different calibration and imaging schemes, with its diameter and width remaining stable over four different observations carried out in different days. Overall, the observed image is consistent with expectations for the shadow of a Kerr black hole as predicted by general relativity. The asymmetry in brightness in the ring can be explained in terms of relativistic beaming of the emission from a plasma rotating close to the speed of light around a black hole. We compare our images to an extensive library of ray-traced general-relativistic magnetohydrodynamic simulations of black holes and derive a central mass of M = (6.5 ± 0.7) × 109 Me. Our radio-wave observations thus provide powerful evidence for the presence of supermassive black holes in centers of galaxies and as the central engines of active galactic nuclei. They also present a new tool to explore gravity in its most extreme limit and on a mass scale that was so far not accessible. Copyright © 2019, The Authors. All rights reserved.

关键词： Gravitation

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On the Probability of Unsafe Disagreement in Group Formation Algorithms for Vehicular Ad Hoc Networks

On the Probability of Unsafe Disagreement in Group Formation...

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European Dependable Computing Conference (EDCC)

作者： Negin Fathollahnejad Risat Pathan Johan Karlsson Department of Computer Science and Engineering Chalmers University of Technology Gothenburg Sweden

ISBN: (纸本)9781467392907

We address the problem of group formation in automotive cooperative applications using wireless vehicle-to-vehicle communication. Group formation (GF) is an essential step in bootstrapping self-organizing distributed applications such as virtual traffic lights. We propose a synchronous GF algorithm and investigate its behaviour in the presence of an unbounded number of asymmetric communication failures (receive omissions). Given that GF is an agreement problem, we know from previous research that it is impossible to design a GF algorithm that can guarantee agreement on the group membership in the presence of an unbounded number of messages losses. Thus, under this assumption, disagreement is an unavoidable outcome of a GF algorithm. We consider two types of disagreement(failure modes): safe and unsafe disagreement. To reduce the probability of unsafe disagreement, our algorithm uses a local oracle to estimate the number of nodes that are attempting to participate in the GF process. (Such estimates can be provided by roadside sensors or local sensors in a vehicle such as cameras.)For the proposed algorithm, we show how the probability of unsafe and safe disagreement varies for different system settings as a function of the probability of message loss. We also show how these probabilities vary depending on the correctness of the local oracles. More specifically, our results show that unsafe disagreement occurs only if the local oracles underestimates the number of participating nodes.

关键词： Algorithm design and analysis Protocols Automobiles Vehicular ad hoc networks Wireless communication Automotive engineering

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A Comparison of Inject-on-Read and Inject-on-Write in ISA-Level Fault Injection

A Comparison of Inject-on-Read and Inject-on-Write in ISA-Le...

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European Dependable Computing Conference (EDCC)

作者： Behrooz Sangchoolie Fatemeh Ayatolahi Roger Johansson Johan Karlsson Department of Computer Science and Engineering Chalmers University of Technology Gothenburg Sweden

ISBN: (纸本)9781467392907

ISA-level fault injection, i.e. the injection of bit-flip faults in Instruction Set Architecture (ISA) registers and main memory words, is widely used for studying the impact of transient and intermittent hardware faults in computer systems. This paper compares two techniques for ISA-level fault injection: inject-on-read, and inject-on-write. The first technique injects bit-flips in a data-item (the content of a register or memory word) just before the data-item is read by a machine instruction, while the second one injects bit-flips in a data-item just after it has been updated by a machine instruction. In addition, the paper compares two variants of inject-on-read, one where all faults are given the same weight and one where weight factors are used to reflect the time a data-item spends in a register or memory word. The weighted injected-on-read aims to accurately model soft errors that occur when an ionizing particle perturbs a data-item while it resides in an ISA register or a memory word. This is in contrast to inject-on-write, which emulates errors that propagate into an ISA register or a memory word. Our experiments show significant differences in the results obtained with the three techniques.

关键词： Registers Hardware Assembly Software Probability Benchmark testing Brakes

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