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Exploring inquiry learning: An EngageCSEdu author and a user discuss POGIL

ACM Inroads 2017年第3期8卷 27-30页

作者： Kussmaul, Clifton Brinkman, Bo Quinn, Beth A. Muhlenberg College Department of Mathematics and Computer Science United States Miami University College of Engineering and Computing Computer Science and Software Engineering United States University of Colorado at Boulder National Center for Women and Information Technology United States

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VFlash: Virtualized Flash for Optimizing the I/O Performance in Mobile Devices

VFlash: Virtualized Flash for Optimizing the I/O Performance...

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作者： Chen, Renhai Wang, Yi Hu, Jingtong Liu, Duo Shao, Zili Guan, Yong Beijing Advanced Innovation Center for Imaging Technology Beijing100048 China College of Information Engineering Capital Normal University Beijing China College of Computer Science and Software Engineering Shenzhen University Shenzhen518060 China School of Electrical and Computer Engineering Oklahoma State University StillwaterOK74074 United States College of Computer Science Chongqing University Chongqing400044 China Embedded Systems and CPS Laboratory Department of Computing Hong Kong Polytechnic University Hong Kong

I/O is becoming one of major performance bottlenecks in NAND-flash-based mobile devices. Novel nonvolatile memories (NVMs), such as phase change memory and spin-transfer torque random access memory, can provide fast read/write operations. In this paper, we propose a unified NVM/flash architecture to improve the I/O performance. A transparent scheme, virtualized flash (vFlash), is also proposed to manage the unified architecture. Within vFlash, interapp and intra-app techniques are proposed to optimize the application performance by exploiting the historical locality and I/O access patterns of applications. Since vFlash is on the bottom of the I/O stack, the application features will be lost. Therefore, we also propose a cross-layer technique to transfer the application information from the application layer to the vFlash layer. The proposed scheme is evaluated based on an Android platform, and the experimental results show that the proposed scheme can effectively improve the I/O performance of mobile devices. © 1982-2012 IEEE.

关键词： Phase change memory

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Physical origins of ruled surfaces on the reduced density matrices geometry

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science China(Physics,Mechanics & Astronomy) 2017年第2期60卷 1-8页

作者： Ji-Yao Chen Zhengfeng Ji Zheng-Xin Liu Xiaofei Qi Nengkun Yu Bei Zeng Duanlu Zhou State Key Laboratory of Low Dimensional Quantum Physics Department of Physics Tsinghua University Beijing 100084 China Perimeter Institute for Theoretical Physics Waterloo N2L 2Y5 Canada Centre for Quantum Computation ＆ Intelligent Systems School of Software Faculty of Engineering and Information Technology University of Technology Sydney Sydney 2007 Australia State Key Laboratory of Computer Science Institute of Software Chinese Academy of Sciences Beijing 100190 China Department of Physics Renmin University of China Beijing 100872 China Department of Mathematics Shanxi University Taiyuan 030000 China Institute for Quantum Computing University of Waterloo Waterloo N2L 3G1 Canada Department of Mathematics ＆ Statistics University of Guelph Guelph N1G 2W1 Canada Institute of Physics Chinese Academy of Sciences Beijing 100190 China

The reduced density matrices （RDMs） of many-body quantum states form a convex set. The boundary of low dimensional projections of this convex set may exhibit nontrivial geometry such as ruled surfaces. In this paper, we study the physical origins of these ruled surfaces for bosonic systems. The emergence of ruled surfaces was recently proposed as signatures of symmetry- breaking phase. We show that, apart from being signatures of symmetry-brealdng, ruled surfaces can also be the consequence of gapless quantum systems by demonstrating an explicit example in terms of a two-mode Ising model. Our analysis was largely simplified by the quantum de Finetti＇s theorem--in the limit of large system size, these RDMs are the convex set of all the symmetric separable states. To distinguish ruled surfaces originated from gapless systems from those caused by symmetry- breaking, we propose to use the finite size scaling method for the corresponding geometry. This method is then applied to the two-mode XY model, successfully identifying a ruled surface as the consequence of gapless systems.

关键词： ruled surfaces reduced density matrices bosonic system geometry

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Joint product numerical range and geometry of reduced density matrices

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science China(Physics,Mechanics & Astronomy) 2017年第2期60卷 9-17页

作者： Jianxin Chen Cheng Guo Zhengfeng Ji Yiu-Tung Poon Nengkun YU Bei Zeng Jie Zhou Joint Center for Quantum Information and Computer Science University of Maryland College Park 20740 USA Institute for Advanced Study Tsinghua University Beijing 100084 China Centre for Quantum Computation ＆ Intelligent Systems School of Software Faculty of Engineering and Information Technology University of Technology Sydney Sydney 2007 Australia State Key Laboratory of Computer Science.Institute of Software Chinese Academy of Sciences Beijing 100084 China Department of Mathematics Iowa State University Ames 50011-2140 USA Institute for Quantum Computing University of Waterloo Waterloo N2L 3G1 Canada Department of Mathematics ＆ Statistics University of Guelph Guelph N1G 2 W1 Canada Perimeter Institute for Theoretical Physics Waterloo N2L 2Y5 Canada

The reduced density matrices of a many-body quantum system form a convex set, whose three-dimensional projection is convex in R3. The boundary of may exhibit nontrivial geometry, in particular ruled surfaces. Two physical mechanisms are known for the origins of ruled surfaces： symmetry breaking and gapless. In this work, we study the emergence of ruled surfaces for systems with local Hamiltonians in infinite spatial dimension, where the reduced density matrices are known to be separable as a consequence of the quantum de Finetti＇s theorem. This allows us to identify the reduced density matrix geometry with joint product numerical range II of the Hamiltonian interaction terms. We focus on the case where the interaction terms have certain structures, such that a ruled surface emerges naturally when taking a convex hull of ∏. We show that, a ruled surface on sitting in ∏ has a gapless origin, otherwise it has a symmetry breaking origin. As an example, we demonstrate that a famous ruled surface, known as the oloid, is a possible shape of , with two boundary pieces of symmetry breaking origin separated by two gapless lines.

关键词： reduced density matrices quantum tomography numerical range quantum information oloid ruled surface

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Energetics of oxygen-octahedra rotations in perovskite oxides from first principles

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Physical Review B 2018年第2期97卷 024113-024113页

作者： Peng Chen Mathieu N. Grisolia Hong Jian Zhao Otto E. González-Vázquez L. Bellaiche Manuel Bibes Bang-Gui Liu Jorge Íñiguez Materials Research and Technology Department Luxembourg Institute of Science and Technology (LIST) 5 avenue des Hauts-Fourneaux L-4362 Esch/Alzette Luxembourg Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Science Beijing 100190 China Unité Mixte de Physique CNRS Thales Université Paris Sud Université Paris-Saclay 1 avenue A. Fresnel 91767 Palaiseau France Scientific Computing & Software for Experiments Department Sincrotrone Elettra 34149 Basovizza Trieste Italy Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) Campus UAB 08193 Bellaterra Spain Physics Department and Institute for Nanoscience and Engineering University of Arkansas Fayetteville Arkansas 72701 USA

We use first-principles methods to investigate the energetics of oxygen-octahedra rotations in ABO3 perovskite oxides. We focus on the short-period, perfectly antiphase or in-phase, tilt patterns that characterize the structure of most compounds and control their physical (e.g., conductive, magnetic) properties. Based on an analytical form of the relevant potential energy surface, we discuss the conditions for the stability of various polymorphs presenting different rotation patterns, and obtain numerical results for a collection of thirty-five representative materials. Our results reveal the mechanisms responsible for the frequent occurrence of a particular structure that combines antiphase and in-phase rotations, i.e., the orthorhombic Pbnm phase displayed by about half of all perovskite oxides, as well as by many nonoxidic perovskites. In essence, the Pbnm phase benefits from the simultaneous occurrence of antiphase and in-phase tilt patterns that compete with each other, but not as strongly as to be mutually exclusive. We also find that secondary antipolar modes, involving the A cations, contribute to weaken the competition between tilts of different types, and thus play a key role in the stabilization of the Pbnm structure. Our results thus confirm and better explain previous observations for particular compounds in the literature. Interestingly, we also find that strain effects, which are known to be a major factor governing phase competition in related (e.g., ferroelectric) perovskite oxides, play no essential role as regards the relative stability of different rotational polymorphs. Further, we discuss why the Pbnm structure stops being the ground state in two opposite limits—namely, for large and small A cations—showing that very different effects become relevant in each case. Our work thus provides a comprehensive discussion and reference data on these all-important and abundant materials, which will be useful to better understand existing compounds as wel

关键词： Crystal structure Ferroelasticity Phase diagrams Structural properties Perovskites Density functional theory

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Usability Evaluation of a Mobile Application in Extraordinary Environment for Extraordinary People

arXiv

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arXiv 2017年

作者： Bhuiyan, Moniruzzaman Zaman, Ambreen Miraz, Mahdi H. Institute of Information Technology University of Dhaka Dhaka Bangladesh Department of Computing Glyndŵr University Wrexham United Kingdom Department of Computer Science & Software Engineering University of Hail Saudi Arabia

- In a contemporary world, people become dependent on electronic devices. Technologies help to clarification and structure life in many ways to meet the need of the children oriented requirements. The children suffering from disabilities (e.g. autism) has desperate needs for elucidation and structures their life. MumIES is a research based system facilitates to support and manage their living. This paper works on MumIES system to evaluate usability of the system in extraordinary environment for extraordinary people. The paper shows from the survey observation users need supporting tools to access the children’s potential and challenges and to give the full support to overcome disabilities. Usability evaluation has been considered one of the key challenges to MumIES system. The paper represents analysis, design of usability studies for the extraordinary user in environment. Copyright © 2017, The Authors. All rights reserved.

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The CECAM Electronic Structure Library and the modular software development paradigm

arXiv

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arXiv 2020年

作者： Oliveira, Micael J. T. Papior, Nick Pouillon, Yann Blum, Volker Artacho, Emilio Caliste, Damien Corsetti, Fabiano Gironcoli, Stefanode Elena, Alin M. Garca, Alberto Garca-Suarez, Vctor M. Genovese, Luigi Huhn, William P. Huhs, Georg Kokott, Sebastian Kucukbenli, Emine Larsen, Ask H. Lazzaro, Alo Lebedeva, Irina V. Li, Yingzhou Lopez-Duran, David Lopez-Tarifa, Pablo Luders, Martin Marques, Miguel A. L. Minar, Jan Mohr, Stephan Mosto, Arash A. O'Cais, Alan Payne, Mike C. Ruh, Thomas Smith, Daniel G. A. Soler, Jose M. Strubbe, David A. Tancogne-Dejean, Nicolas Tildesley, Dominic Torrent, Marc Wen-Zhe, Victor Max Planck Institute for the Structure and Dynamics of Matter HamburgD-22761 Germany DTU Computing Center Technical University of Denmark Lyngby2800 Denmark Departamento CITIMAC Universidad de Cantabria Santander Spain Simune Atomistics San Sebastian20018 Spain Department of Mechanical Engineering and Materials Science Duke University DurhamNC27708 United States Department of Chemistry Duke University DurhamNC27708 United States CIC Nanogune BRTA DIPC San Sebastian20018 Spain Ikerbasque Basque Foundation for Science Bilbao48011 Spain Theory of Condensed Matter Cavendish Laboratory University of Cambridge CambridgeCB30HE United Kingdom Department of Physics IRIG Univ. Grenoble Alpes CEA GrenobleF-38000 France Departments of Materials and Physics Thomas Young Centre for Theory and Simulation of Materials Imperial College London LondonSW72AZ United Kingdom Synopsys Denmark Copenhagen2100 Denmark Scuola Internazionale Superiore di Studi Avanzati Trieste34136 Italy Scientific Computing Department Daresbury Laboratory WarringtonWA44AD United Kingdom Institut de Ciencia de Materials de Barcelona BellaterraE-08193 Spain Departamento de Fisica Universidad de Oviedo CINN Oviedo33007 Spain Barcelona Supercomputing Center Barcelona08034 Spain Fritz Haber Institut Berlin14195 Germany John A. Paulson School of Engineering and Applied Sciences Harvard University CambridgeMA02138 United States Nano-Bio Spectroscopy Group ETSF Departamento de Fisica de Materiales Universidad Del Pais Vasco San Sebastian20018 Spain Department of Chemistry University of Zurich ZurichCH-8057 Switzerland CIC Nanogune BRTA San Sebastian20018 Spain Department of Mathematics Duke University DurhamNC27708-0320 United States Centro de Fisica de Materiales Centro Mixto CSIC-UPV San Sebastian20018 Spain Institut fur Physik Martin-Luther-Universitat Halle-Wittenberg Halle Saale06120 Germany New Technologies Research Centre University of West Bohemia Plzen3

First-principles electronic structure calculations are now accessible to a very large community of users across many disciplines thanks to many successful software packages, some of which are described in this special issue. The traditional coding paradigm for such packages is monolithic, i.e., regardless of how modular its internal structure may be, the code is built independently from others, essentially from the compiler up, possibly with the exception of linear-algebra and message-passing libraries. This model has endured and been quite successful for decades. The successful evolution of the electronic structure methodology itself, however, has resulted in an increasing complexity and an ever longer list of features expected within all software packages, which implies a growing amount of replication between different packages, not only in the initial coding but, more importantly, every time a code needs to be re-engineered to adapt to the evolution of computer hardware architecture. The Electronic Structure Library (ESL) was initiated by CECAM (the European Centre for Atomic and Molecular Calculations) to catalyze a paradigm shift away from the monolithic model and promote modularization, with the ambition to extract common tasks from electronic structure codes and redesign them as open-source libraries available to everybody. Such libraries include, e.g., \heavy-duty"ones that have the potential for a high degree of parallelisation and adaptation to novel hardware within them, thereby separating the sophisticated computer science aspects of performance optimization and reengineering from the computational science done by, e.g., physicists and chemists when implementing new ideas. We envisage that this modular paradigm will improve overall coding eficiency and enable specialists (whether they be computer scientists or computational scientists) to use their skills more effectively, and will lead to a more dynamic evolution of software in the community as well as

关键词： Libraries

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Taming the big to small: efficient selfish task allocation in mobile crowdsourcing systems

Taming the big to small: efficient selfish task allocation i...

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作者： Li, Qingyu Yang, Panlong Fan, Xiaochen Tang, Shaojie Xiang, Chaocan Guo, Deke Li, Fan China Satellite Maritime Tracking and Control Department Jiangyin China College of Communications Engineering PLA University of Science and Technology Nanjing China University of Texas at Dallas RichardsonTX United States Logistic Engineering University of PLA Chongqing China National University of Defense Technology Changsha China Beijing Institute of Technology Beijing China School of Computer Science and Technology University of Science and Technology of China Hefei China School of Computer and Software Nanjing University of Information Science and Technology Nanjing China School of Computing and Communications Faculty of Engineering and Information Technology University of Technology Sydney UltimoNSW Australia

This paper investigates the selfish load balancing problem in mobile distributed crowdsourcing networks. Conventional methods heavily relied on cooperation among users to achieve balanced resource utilization in a platform-centric view. In achieving fairly low communication and computational overhead, this work leverages the d-choice method based on Ball and Bin theory for effective balancing under limited information and the Proportional Allocation scheme for selfish load balancing, maintaining good load balancing property among selfish users. Even with limited information, the balancing performance could be improved significantly. Moreover, theoretical analysis has been presented in convergence property. Extensive evaluations have been made to show that Chance-Choice outperforms several existing algorithms. Typically, comparing with Proportional Allocation scheme, it could decrease the load gap between the maximum and the minimal in system by 50% to 80% and reduce the overhead complexity from O(n) to O(1) comparing with the Max-weight Best Response algorithm, where n denotes the number of mobile users in a crowdsourcing system. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

关键词： Crowdsourcing

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Bug Report Enrichment with Application of Automated Fixer Recommendation

Bug Report Enrichment with Application of Automated Fixer Re...

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IEEE Workshop on Program Comprehension

作者： Tao Zhang Jiachi Chen He Jiang Xiapu Luo Xin Xia College of Computer Science and Technology Harbin Engineering University China Department of Computing The Hong Kong Polytechnic University Hong Kong School of Software Dalian University of Technology China Department of Computer Science University of British Columbia Canada

ISBN: (纸本)9781538605363

For large open source projects (e.g., Eclipse, Mozilla), developers usually utilize bug reports to facilitate software maintenance tasks such as fixer assignment. However, there are a large portion of short reports in bug repositories. We find that 78.1% of bug reports only include less than 100 words in Eclipse and require bug fixers to spend more time on resolving them due to limited informative contents. To address this problem, in this paper, we propose a novel approach to enrich bug reports. Concretely, we design a sentence ranking algorithm based on a new textual similarity metric to select the proper contents for bug report enrichment. For the enriched bug reports, we conduct a user study to assess whether the additional sentences can provide further help to fixer assignment. Moreover, we assess whether the enriched versions can improve the performance of automated fixer recommendation. In particular, we perform three popular automated fixer recommendation approaches on the enriched bug reports of Eclipse, Mozilla, and GNU Compiler Collection (GCC). The experimental results show that enriched bug reports improve the average F-measure scores of the automated fixer recommendation approaches by up to 10% for DREX, 13.37% for DRETOM, and 8% for DevRec when top-10 bug fixers are recommended.

关键词： Computer bugs Delays Computer science Algorithm design and analysis Natural languages software maintenance

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Advances in quantum cryptography

arXiv

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arXiv 2019年

作者： Pirandola, S. Andersen, U.L. Banchi, L. Berta, M. Bunandar, D. Colbeck, R. Englund, D. Gehring, T. Lupo, C. Ottaviani, C. Pereira, J. Razavi, M. Shaari, J.S. Tomamichel, M. Usenko, V.C. Vallone, G. Villoresi, P. Wallden, P. Computer Science and York Centre for Quantum Technologies University of York YorkYO10 5GH United Kingdom CambridgeMA02139 United States Department of Physics Technical University of Denmark Fysikvej 2800 Kgs. Lyngby2800 Denmark I-50019 Italy Department of Computing Imperial College Kensington LondonSW7 2AZ United Kingdom Department of Mathematics University of York YorkYO10 5DD United Kingdom Department of Physics and Astronomy University of Sheffield SheffieldS3 7RH United Kingdom School of Electronic and Electrical Engineering University of Leeds LeedsLS2 9JT United Kingdom Jalan Sultan Ahmad Shah Kuantan Pahang25200 Malaysia University Putra Malaysia 43400 UPM Serdang Selangor Malaysia Centre for Quantum Software and Information School of Software University of Technology Sydney SydneyNSW2007 Australia Department of Optics Palacky University 17. listopadu 50 Olomouc772 07 Czech Republic Dipartimento di Ingegneria dell’Informazione Universitá degli Studi di Padova Via Gradenigo 6B Padova35131 Italy School of Informatics University of Edinburgh 10 Crichton Street EdinburghEH8 9AB United Kingdom

Quantum cryptography is arguably the fastest growing area in quantum information science. Novel theoretical protocols are designed on a regular basis, security proofs are constantly improving, and experiments are gradually moving from proof-of-principle lab demonstrations to in-field implementations and technological prototypes. In this review, we provide both a general introduction and a state of the art description of the recent advances in the field, both theoretically and experimentally. We start by reviewing protocols of quantum key distribution based on discrete variable systems. Next we consider aspects of device independence, satellite challenges, and high rate protocols based on continuous variable systems. We will then discuss the ultimate limits of point-to-point private communications and how quantum repeaters and networks may overcome these restrictions. Finally, we will discuss some aspects of quantum cryptography beyond standard quantum key distribution, including quantum data locking and quantum digital signatures. Copyright © 2019, The Authors. All rights reserved.

关键词： Quantum cryptography

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