关键词： 分布式   图处理系统   高性能   RDMA   动态负载均衡   RDMA通信模型  

摘要： 图是描述实体间关系的重要数据结构,被广泛地应用于信息科学、物理学、生物学、环境生态学等重要的科学领域.现如今,随着图数据规模的不断增大,利用分布式系统来处理大图数据已经成为主流,出现了形如Pregel、GraphX、Power Graph和Gemini等经典的分布式大图数据处理系统.然而,与当前先进的基于单机的图处理系统相比,这些经典的分布式图处理系统在处理真实的图数据时并没有充足或稳定的性能优势.分析了几个有代表性的分布式图处理系统,总结并归纳出了影响其性能的主要挑战.通过对这些挑战的深入研究,提出了RGraph——一个基于RDMA的高效分布式大图数据处理系统.RGraph旨在通过充分利用RDMA的优势来提升图处理系统多个方面的性能.在图划分方面,RGraph采用基于块的划分方式避免破坏原始图数据的局部性,从而保证顶点的高效访问.在负载方面,RGraph提出了基于RDMA单边READ的任务迁移机制和线程间细粒度的任务抢夺方式来分别保证计算节点间以及计算节点内线程间的动态负载均衡,确保集群中的所有计算资源能够被充分利用.在通信方面,RGraph通过对IB verbs的有效封装,实现了符合图计算语义的多线程RDMA通信模型.相比于传统的MPI,RGraph的通信机制可以减少计算节点间2.1倍以上的通信延迟.最后,利用5个真实大图数据集和1个合成数据集,在拥有8个计算节点的高性能集群上测试了RGraph.实验结果表明,RGraph具有明显的性能优势.相比于Powergraph,RGraph具有10.1-16.8倍的加速比,与当前最先进的分布式图处理系统相比,RGraph的加速比仍能达到2.89-5.12倍.同时,RGraph在极度偏斜的幂律图上也能保证稳定的性能优势.

关键词： Hive   HQL   MapReduce  

摘要： Hive是一种建立在Hadoop上的数据仓库基础构架。Hive系统结构中的解析器,可以将用户编写的HiveQL语句进行解析,解析出相应的MapReduce程序,本文使用Hive对某网站用户评论数据进行分析,快速实现MapReduce统计任务。

关键词： 步冷曲线法   过冷度   数据库   管理信息系统   数据处理  

摘要： 本文利用Delphi开发工具结合Sybase数据库开发了一种适用于实验室的管理信息系统,开展与建筑材料相关的课题研究。在利用数据库对实验测温记录进行管理的基础上,开发了包含温度数据预处理、温度曲线过冷度读取、试样配方数据录入管理、实验数据处理、处理结果输出等五个模块的数据处理软件,通过人机交互处理来实现实验数据由录入、处理到结果输出的整个流程。应用表明,采用数据库与管理信息系统技术,可以在实验数据日常管理与维护,以及图形绘制、显示与图片文件规范化输出的过程中,极大地减轻工作量,提高数据处理的速度与效率。

关键词： 基因   数据处理   数据归档   标准化  

摘要： 本文首先论述了基因组信息数据的产生及其重要的科学意义,并对国内外基因行业发展趋势进行阐述。通过对比目前国内外基因组信息数据的标准情况,强调研制基因组数据处理及归档相关标准的必要性和重要性,明确了我国需加强国际标准化活动的参与度,并提出标准项目建设构想。

关键词： GAMIT   数据处理   IGS站   标准均方根   基线重复率  

摘要： 随着高精度GNSS在地学中的应用越来越广泛,如何提高GNSS数据处理精度成为一个热点问题。IGS站的选取对GNSS数据处理的精度起着重要的作用。论文以GNSS数据处理软件GAMIT进行数据处理为例,从IGS站选取的几何意义和统计意义,研究其对GNSS数据处理精度的影响。通过比较和分析,说明合理先取IGS站点能够有效提高基线解算的精度,并对合理选取IGS站点的方法提出建议。

关键词： forward model   Abel integral   radio occultation data processing   interpolation of a forward model   evaluation of forward model   sensitivity of forward model  

摘要： In radio occultation (RO) data processing and data assimilation, the forward model (FM) is used to calculate bending angle (BA) from refractivity (N). The accuracy and precision of forward modeled BA are affected by refractivity profiles and FM methods, including Abel integral algorithms (direct, exp, exp_T, linear) and methods of interpolating refractivity during integral (log-cubic spline and log-linear). Experiment 1 compares these forward model methods by comparing the difference and relative difference (RD) of the experimental value (forward modeled ECMWF analysis) and the true value (BA of FY3D RO data). Results suggested that the exp with log-cubic spline (log-cubic) interpolation is the most accurate FM because it has better integral accuracy (less than 2%) to inputs, especially when the input is lower than an order of magnitude of 1 x 10(-2) (that is, above 60 km). By contrast, the direct induced a 10% error, and the improvement of exp T to exp is limited. Experiment 2 simulated the exact errors of an FM (exp) based on inputs on different vertical resolutions. The inputs are refractivity profiles on model levels of three widely used analyses, including ECMWF 4Dvar analysis, final operational global analysis data (FNL), and ERA5. Results demonstrated that based on exp and log-cubic interpolation, BA on model level of ECMWF 4Dvar has the highest accuracy, whose RD is 0.5% between 0-35 km, 4% between 35-58 km, and 1.8% between 58-80 km. By contrast, the other two analyses have low accuracy. This paper paves the way to better understanding the FM, and simulation errors on model levels of three analyses can be a helpful FM error reference.

关键词： Combination index   Dual antiplatelet therapy   Platelet inhibitors   Regression   Synergism  

摘要： Introduction: The combination index (CI), a common quantitative indicator of the degree of synergy/antagonism, may be determined using different regression methods. However, any analysis with constraints has the potential for underestimating the combined effect of multiple drugs. Objectives: This in vitro study describes the combined effects of selected platelet antagonists on ADP-induced platelet activation in different regression models. Methods: The inhibitory effects of P2Y(12) receptor antagonists in combination with P2Y(1) receptor antagonists (i.e. cangrelor with MRS 2279, prasugrel metabolite with MRS 2179 and PSB 0739 with MRS 2179) were characterized with the aid of three software packages: CompuSyn (for linear regression with constraints), CISNE (for non-linear regression with constraints) and GraphPad Prism (for non-linear regression without constraints). The synergism between P2Y(12) and P2Y(1) inhibitors was quantified by CI and synergy area. Results: MRS 2279 and MRS 2179 were found to act synergistically with selected P2Y(12) receptor antagonists to potentiate their antiplatelet effect. The models of regression with constraints, linear regression in particular, demonstrated a worse fit for experimental data than non-linear regression without constraints;this resulted in an incorrect estimation of the combined effects of two antiplatelet drugs, i.e., underestimating the CI and over-estimating the synergy area. Also, the synergy area was found to better reflect the differences among models than the CI. Conclusions: These findings suggest that non-linear regression without constraints offers more precise quantitative determination of combined effects between two drugs compared to the regression models with constraints.

关键词： Strong data processing inequality (SDPI)   contraction coefficient   f-divergence  

摘要： For any channel P-Y vertical bar X the strong data processing constant is defined as the smallest number eta(KL) is an element of [0,1] such that I(U;Y) <= eta I-KL(U;X) holds for any Markov chain U - X - Y. It is shown that the value of eta(KL) is given by that of the best binary-input subchannel of P-Y vertical bar X. The same result holds for any f-divergence, verifying a conjecture of Cohen, Kemperman and Zbaganu (1998).

关键词： 生态环境   数据处理  

ISBN: (纸本)9787030699732

摘要： 当今生态学已经发展到大科学、大数据、大理论时代，生态大数据的集成分析与信息挖掘逐渐成为地球系统科学研究的重要手段。

关键词： Allosteric regulation   Enzyme evolution   Post-translational regulation   Redox regulation   Subfunctionalization   Nucleotide-sugar synthesis  

摘要： Key message This review outlines research performed in the last two decades on the structural, kinetic, regulatory and evolutionary aspects of ADP-glucose pyrophosphorylase, the regulatory enzyme for starch biosynthesis. ADP-glucose pyrophosphorylase (ADP-Glc PPase) catalyzes the first committed step in the pathway of glycogen and starch synthesis in bacteria and plants, respectively. Plant ADP-Glc PPase is a heterotetramer allosterically regulated by metabolites and post-translational modifications. In this review, we focus on the three-dimensional structure of the plant enzyme, the amino acids that bind the regulatory molecules, and the regions involved in transmitting the allosteric signal to the catalytic site. We provide a model for the evolution of the small and large subunits, which produce heterotetramers with distinct catalytic and regulatory properties. Additionally, we review the various post-translational modifications observed in ADP-Glc PPases from different species and tissues. Finally, we discuss the subcellular localization of the enzyme found in grain endosperm from grasses, such as maize and rice. Overall, this work brings together research performed in the last two decades to better understand the multiple mechanisms involved in the regulation of ADP-Glc PPase. The rational modification of this enzyme could improve the yield and resilience of economically important crops, which is particularly important in the current scenario of climate change and food shortage.