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Towards Cost-Effective Cloud Downloading with Tencent Big Data

Journal of Computer Science & Technology 2015年第6期30卷 1163-1174页

作者：李振华刘刚嵇智源 roger zimmermann School of Software Tsinghua University Beijing 100084 China Tsinghua National Laboratory for Information Science and Technology Beijing 100084 China QQXuanfeng System Group Tencent Co. Ltd Shanghai 200233 China High Technology Research and Development Center Ministry of Science and Technology Beijing 10004 China Department of Computer Science National University of Singapore Singapore 117417 Singapore

The cloud downloading scheme, first proposed by us in 2011, has effectively optimized hundreds of millions of users＇ downloading experiences. Also, people start to build a variety of useful Internet services on top of cloud downloading. In brief, by using cloud facilities to download （and cache） the requested file from the ＂best-effort＂ Internet on behalf of the user, cloud downloading ensures the data availability and remarkably enhances the data delivery speed. Although this scheme seems simple and straightforward, designing a real-world cloud downloading system involves complicated and subtle trade-offs （between deployment cost and user experience） when serving a large number of users： 1） how to plan the cloud cache capacity to achieve a high and affordable cache hit ratio, 2） how to accelerate the data delivery from the cloud to numerous users, 3） how to handle the dense user requests for highly popular files, and 4） how to judge a potential downloading failure of the cloud. This paper addresses these design trade-offs from a practical perspective, based on big data from a nationwide commercial cloud downloading system, i.e., Tencent QQXuanfeng. Its running traces help us find reasonable design strategies and parameters, and its real performances confirm the efficacy of our design. Our study provides solid experiences and valuable heuristics for the developers of similar and relevant systems.

关键词： cloud downloading cost-effective design trade-off big data

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Skyline-join query processing in distributed databases

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Frontiers of Computer Science 2016年第2期10卷 330-352页

作者： Mei BAI Junchang XIN Guoren WANG roger zimmermann Xite WANG College of Information Science and Engineering Northeastern University Shenyang 110819 China School of Computing National University of Singapore Singapore 117417 Singapore

The skyline-join operator, as an important variant of skylines, plays an important role in multi-criteria decision making problems. However, as the data scale increases, previous methods of skyline-join queries cannot be applied to new applications. Therefore, in this paper, it is the first attempt to propose a scalable method to process skyline-join queries in distributed databases. First, a tailored distributed framework is presented to facilitate the computation of skyline-join queries. Second, the distributed skyline-join query algorithm （DSJQ） is designed to process skyline-join queries. DSJQ contains two phases. In the first phase, two filtering strategies are used to filter out unpromising tuples from the original tables. The remaining tuples are transmitted to the corresponding data nodes according a partition function, which can guarantee that the tuples with the same join value are transferred to the same node. In the second phase, we design a scheduling plan based on rotations to calculate the final skyline-join result. The scheduling plan can ensure that calculations are equally assigned to all the data nodes, and the calculations on each data node can be processed in parallel without creating a bottleneck node. Finally, the effectiveness of DSJQ is evaluated through a series of experiments.

关键词： skyline-join distributed filtering strategy scheduling plan rotation

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Effcient Location Updates for Continuous Queries over Moving Objects

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Journal of Computer Science & Technology 2010年第3期25卷 415-430页

作者：薛幼苓 roger zimmermann 顾维信 Department of Computer Science University of Southern California Department of Computer Science National University of Singapore Department of Computer Science and Software Engineering Auburn University

The significant overhead related to frequent location updates from moving objects often results in poor performance. As most of the location updates do not affect the query results, the network bandwidth and the battery life of moving objects are wasted. Existing solutions propose lazy updates, but such techniques generally avoid only a small fraction of all unnecessary location updates because of their basic approach （e.g., safe regions, time or distance thresholds）. Furthermore, most prior work focuses on a simplified scenario where queries are either static or rarely change their positions. In this study, two novel efficient location update strategies are proposed in a trajectory movement model and an arbitrary movement model, respectively. The first strategy for a trajectory movement environment is the Adaptive Safe Region （ASR） technique that retrieves an adjustable safe region which is continuously reconciled with the surrounding dynamic queries. The communication overhead is reduced in a highly dynamic environment where both queries and data objects change their positions frequently. In addition, we design a framework that supports multiple query types （e.g., range and c-kNN queries）. In this framework, our query re-evaluation algorithms take advantage of ASRs and issue location probes only to the affected data objects, without flooding the system with many unnecessary location update requests. The second proposed strategy for an arbitrary movement environment is the Partition-based Lazy Update （PLU, for short） algorithm that elevates this idea further by adopting Location Information Tables （LITs） which （a） allow each moving object to estimate possible query movements and issue a location update only when it may affect any query results and （b） enable smart server probing that results in fewer messages. We first define the data structure of an LIT which is essentially packed with a set of surrounding query locations across the terrain and discuss the mobile-

关键词： location updates continuous queries location-based services

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A sphingolipid message promotes neuronal health across generations

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Neural Regeneration Research 2024年第11期19卷 2325-2326页

作者： Wenyue Wang roger Pocock Development and Stem Cells Program Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental BiologyMonash UniversityMelbourneVICAustralia

Maternal nutrition can affect brain function of offspring in later life(Fitzgerald et al.,2020).Emerging studies have also shown that the maternal environment can modify susceptibility to neurodegenerative disease(Boots et al.,2023).Transmission of environmental information from mother to offspring depends on maternal nutrient *** the nematode Caenorhabditis elegans,maternal yolk,which is synthesized in the intestine and transferred to nourish oocytes and early embryos,can provide extranuclear inheritance factors to mediate phenotypic plasticity across ***,the molecular mechanisms of regulating such intergenerational effects remain largely unknown.

关键词： mother intestine transferred

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Making topological protein links using enzymatic reactions

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National Science Review 2024年第3期11卷 50-51页

作者： roger Castells-Graells Todd O.Yeates Department of Chemistry and Biochemistry University of California UCLA-DOE Institute for Genomics and Proteomics

Proteins are exceedingly complex molecules though, at their heart, they are essentially linear polymers. Pull at their ends and one obtains an extended backbone. While that is true in most cases, some natural proteins... 详细信息

关键词： DESIGN

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Mechanistic modeling of copper corrosions in data center environments

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Building Simulation 2024年第3期17卷 483-492页

作者： Rui Zhang Jianshun Zhang roger Schmidt Jeremy L.Gilbert Department of Mechanical and Aerospace Engineering College of Engineering and Computer ScienceSyracuse UniversitySyracuseNY13244USA Buildings and Transportation Science Division Oak Ridge National LaboratoryOak RidgeTN37830USA SyracuseCoE-New York Center of Excellence in Environmental and Energy Systems Syracuse University727 E.Washington StreetSyracuseNY13244USA Department of Bioengineering Clemson UniversityClemson-Medical University of South Carolina Bioengineering ProgramCharlestonSC29425USA

Air-side economizers are increasingly used to take advantage of“free-cooling”in data centers with the intent of reducing the carbon footprint of ***,they can introduce outdoor pollutants to indoor environment of data centers and cause corrosion damage to the information technology *** evaluate the reliability of information technology equipment under various thermal and air-pollution conditions,a mechanistic model based on multi-ion transport and chemical reactions was *** model was used to predict Cu corrosion caused by Cl_(2)-containing pollutant *** also accounted for the effects of temperature(25℃and 28℃),relative humidity(50%,75%,and 95%),and *** also identified higher air temperature as a corrosion barrier and higher relative humidity as a corrosion accelerator,which agreed well with the experimental *** average root mean square error of the prediction was 13.7Å.The model can be used to evaluate the thermal guideline for data centers design and operation when Cl_(2)is present based on pre-established acceptable risk of corrosion in data centers’environment.

关键词： chloride pollutant mixture copper corrosion model data center temperature relative humidity synergistic effect

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Analyzing voting power in decentralized governance:Who controls DAOs?

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Blockchain(Research and Applications) 2024年第3期5卷 123-129页

作者： Robin Fritsch Marino Müller roger Wattenhofer ETH Zurich 8092ZurichSwitzerland

We empirically study the state of three prominent DAO governance systems on the Ethereum blockchain:Compound,Uniswap and Ethereum name service(ENS).In particular,we examine how the voting power is distributed in these *** a comprehensive dataset of all governance token holders,delegates,propos-als,and votes,we analyze who holds the voting power and how this power is being used to influence governance *** we reveal that the majority of voting power is concentrated in the hands of a small number of addresses,we rarely observe these powerful entities overturning a vote by choosing a different outcome than that of the overall community and less influential voters.

关键词： Decentralized autonomous organization DAO governance Liquid democracy Blockchain

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A framework for dynamic modelling of railway track switches considering the switch blades,actuators and control systems

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Railway Engineering Science 2024年第2期32卷 162-176页

作者： Saikat Dutta Tim Harrison Christopher Ward roger Dixon Phil Winship Institute of Thermofluids School of Mechanical EngineeringUniversity of LeedsLeedsWest YorkshireUK Wolfson School of Mechanical Electrical and Manufacturing EngineeringLoughborough UniversityLoughboroughLeicestershireUK Birmingham Centre for Railway Research and Education School of EngineeringUniversity of BirminghamBirminghamWest MidlandsUK Network Rail Milton KeynesBuckinghamshireUK

The main contribution of this paper is the development and demonstration of a novel methodology that can be followed to develop a simulation twin of a railway track switch system to test the functionality in a digital *** is important because,globally,railway track switches are used to allow trains to change routes;they are a key part of all railway ***,because track switches are single points of failure and safety-critical,their inability to operate correctly can cause significant delays and concomitant *** order to better understand the dynamic behaviour of switches during operation,this paper has developed a full simulation twin of a complete track switch *** approach fuses finite element for the rail bending and motion,with physics-based models of the electromechanical actuator system and the control ***,it provides researchers and engineers the opportunity to explore and understand the design space around the dynamic operation of new switches and switch machines before they are *** is useful for looking at the modification or monitoring of existing switches,and it becomes even more important when new switch concepts are being considered and *** simulation is capable of running in real time or faster meaning designs can be iterated and checked *** paper describes the modelling approach,demonstrates the methodology by developing the system model for a novel“REPOINT”switch system,and evaluates the system level performance against the dynamic performance requirements for the *** the context of that case study,it is found that the proposed new actuation system as designed can meet(and exceed)the system performance requirements,and that the fault tolerance built into the actuation ensures continued operation after a single actuator failure.

关键词： Railway track switch Mathematical modelling Redundant actuation Finite element analysis

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Tuberculosis Prevalence Trends from a Predictive Modelling Study-10 High-Burden Countries,1980-2035

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China CDC weekly 2024年第12期6卷 225-229,I0001,I0002页

作者： Qiuping Chen Qiao Liu Kangguo Li Laurent Gavotte roger Frutos Tianmu Chen CIRAD IntertrypMontpellierFrance Universitéde Montpellier MontpellierFrance State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics National Innovation Platform for Industry-Education Integration in Vaccine ResearchXiamen UniversityXiamen CityFujian ProvinceChina State Key Laboratory of Vaccines for Infectious Diseases Xiang An Biomedicine LaboratorySchool of Public HealthXiamen UniversityXiamen CityFujian ProvinceChina Espace-Dev Universitéde MontpellierMontpellierFrance

What is already known about this topic?Given the challenges presented by drug-resistant strains of tuberculosis(TB)and the rising mobility of the population,achieving the objective of eradicating TB appears *** is added by this report?The examination of TB incidence trends in 10 highburden countries(HBCs)indicated a steady rise in cases,with India and China jointly accounting for nearly 70%of the *** for the future show diverse trajectories in these countries,with potential difficulties in reaching the TB elimination target,especially in Nigeria,Congo,and South *** are the implications for public health practice?The number of TB cases is on the *** is crucial to learn from successful strategies to improve TB prevention and control worldwide through collaborative efforts.

关键词： tuberculosis uncertain Tuberculosis

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Exciton-polaritons in a 2D hybrid organic-inorganic perovskite microcavity with the presence of optical Stark effect

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Chinese Physics B 2024年第3期33卷 551-555页

作者： Kenneth Coker 郑楚媛 Joseph roger Arhin Kwame Opuni-Boachie Obour Agyekum 张伟利 School of Information and Communication Engineering University of Electronic Science and Technology of ChinaChengdu 611731China Department of Electrical and Electronic Engineering Ho Technical UniversityHo 00233Ghana Telecommunication Engineering Department Kwame Nkrumah University of Science and TechnologyKumasi 00233Ghana

This study investigates the properties of exciton-polaritons in a two-dimensional(2D)hybrid organic-inorganic perovskite microcavity in the presence of optical Stark *** both steady and dynamic state analyses,strong coupling between excitons of perovskite and cavity photons is revealed,indicating the formation of polaritons in the perovskite ***,it is found that an external optical Stark pulse can induce energy shifts of excitons proportional to the pulse intensity,which modifies the dispersion characteristics of the polaritons.

关键词： exciton-polaritons perovskite microcavity optical Stark effect

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