An Efficient Crash Recovery Technique for Real-Time Main Memory Database

This paper presents an efficient recovery scheme suitable for real-time mainmemory database. In the recovery scheme, log records are stored in non-volatile RAM which is dividedinto four different partitions based on transaction types. Similarly, a main memory database isdivided into four partitions based data types. When the using ratio of log store area exceeds thethreshold value, checkpoint procedure is triggered. During executing checkpoint procedure, someuseless log records are deleted. During restart recovery after a crash, partition reloading policyis adopted to assure that critical data are reloaded and restored in advance, so that the databasesystem can be brought up before the entire database is reloaded into main memory. Therefore downtime is obvionsly reduced. Simulation experiments show our recovery scheme obviously improves thesystem performance, and does a favor to meet the dtadlints of real-time transactions.

Weak Serializable Concurrency Control in Distributed Real-Time Database Systems

Most of the proposed concurrency control protocols for real time database systems are based on serializability theorem. Owing to the unique characteristics of real time database applications and the importance of satisfying the timing constraints of transactions, serializability is too strong as a correctness criterion and not suitable for real time databases in most cases. On the other hand, relaxed serializability including epsilon serializability and similarity serializability can allow more real time transactions to satisfy their timing constraints, but database consistency may be sacrificed to some extent. We thus propose the use of weak serializability(WSR) that is more relaxed than conflicting serializability while database consistency is maintained. In this paper, we first formally define the new notion of correctness called weak serializability. After the necessary and sufficient conditions for weak serializability are shown, corresponding concurrency control protocol WDHP(weak serializable distributed high priority protocol) is outlined for distributed real time databases, where a new lock mode called mask lock mode is proposed for simplifying the condition of global consistency. Finally, through a series of simulation studies, it is shown that using the new concurrency control protocol the performance of distributed real time databases can be greatly improved.

Validation concurrency control protocol in parallel real-time database systems

In parallel real-time database systems, concurrency control protocols must satisfy time constraints as well as the integrity constraints. The authors present a validation concurrency control(VCC) protocol, which can enhance the performance of real-time concurrency control mechanism by reducing the number of transactions that might miss their deadlines, and compare the performance of validation concurrency control protocol with that of HP2PL(High priority two phase locking) protocol and OCC-TI-WAIT-50(Optimistic concurrency control-time interval-wait-50) protocol under shared-disk architecture by simulation. The simulation results reveal that the protocol the author presented can effectively reduce the number of transactions restarting which might miss their deadlines and performs better than HP2PL and OCC-TI-WAIT-50. It works well when arrival rate of transaction is lesser than threshold. However, due to resource contention the percentage of missing deadline increases sharply when arrival rate is greater than the threshold.

A dynamic crash recovery scheme for distributed real-time database systems

Recovery performance in the event of failures is very important for distributed real-time database systems. This paper presents a time-cognizant logging-based crash recovery scheme （TCLCRS） that aims at distributed real-time databases, which adopts a main memory database as its ground support. In our scheme, each site maintains a real-time log for local transactions and the subtransactions, which execute at the site, and execte local checkpointing independently. Log records are stored in non-volatile high- speed store, which is divided into four different partitions based on transaction classes. During restart recovery after a site crash, partitioned crash recovery strategy is adopted to ensure that the site can be brought up before the entire local secondary database is reloaded in main memory. The partitioned crash recovery strategy not only guarantees the internal consistency to be recovered, but also guarantee the temporal consistency and recovery of the sates of physical world influenced by uncommitted transactions. Combined with two- phase commit protocol, TCLCRS can guarantee failure atomicity of distributed real-time transactions.

Deep-time Paleogeographic Reconstruction Based on Database:Taking the South China T. approximatus Biozone(Early Ordovician) as an Example

Paleogeography is a discipline that studies spatial distribution and evolutionary characteristics of geographic objects in earth history(Feng,2003;Feng et al.,2012).It focuses on the sediments,organisms and environmental proxies,most of which are preserved in the rocks.However,a large amount of this geological and biological information was no longer preserved after the geological process of burial.

A Method for Detecting Adhesive Related-Factors of Streptococcus suis Serotype 2 by Real-time PCR

[Objective] This study aimed to establish a method for quantitative detection of mRNA transcriptional level of SS2 adhesive related-factors of Streptococcus suis serotype 2 （SS2） by fluorescent quantitative PCR. []Vlethod] The gene fragments en- coding SS2 adhesive related-factors MRP, FBPS and CPS2J and a housekeeping gene aroA were amplified by reverse transcription PCR from the total RNA of SS2, cloned, and sequenced. The recombinant plasmids containing the target genes were constructed, and used as templates in Real-time PCR. [Result] Dynamic curves, stan- dard curves and melting curves of the adhesive related-factors and aroA were ob- tained by the optimized Real-time PCR system. The standard curves showed a good linear relationship between template copy number and circulation number, and the correlation coefficients （FF） of the standard curves were over 0.995. Also, these as- says were highly specific a^d there was single specific melting peak for every gene. Moreover, the assays were highly sensitive and had a detection limit of 1.0×102 copies in 1 μl of initial templates. Finally, it was highly repeatable and had a coeffi- cient of variation less than 2% for intra-assay. [Conclusion] This study will provide a way to reveal the adhesion mechanism of SS2 to different host cells at molecular level.

Real-TimeSQL的设计与实现

实时数据库的结构化查询语言RTSQL(Real-TimeSQL)是实时数据库研究的一项重要内容。论文详细论述了RTSQL的一种设计方法,即扩展SQL92标准以支持实时数据库的要求,构建RTSQL语言的方法。文章还介绍了RTSQL在Agilor实时数据库系统中的实现方式。在文章最后给出了RTSQL进一步研究的思路和建议。

Cache-Conscious Index Mechanism for Main-Memory Databases

Recent studies have addressed that the cache be havior is important in the design of main memory index structures. Cache-conscious indices such as the CSB^＋-tree are shown to outperform conventional main memory indices such as the AVL-tree and the T-tree. This paper proposes a cacheconscious version of the T-tree, CST-tree, defined according to the cache-conscious definition. To separate the keys within a node into two parts, the CST-tree can gain higher cache hit ratio.

Use of Dynamical Systems Modeling to Hybrid Cloud Database

In the article, an experiment is aimed at clarifying the transfer efficiency of the database in the cloud infrastructure. The system was added to the control unit, which has guided the database search in the local part or in the cloud. It is shown that the time data acquisition remains unchanged as a result of modification. Suggestions have been made about the use of the theory of dynamic systems to hybrid cloud database. The present work is aimed at attracting the attention of specialists in the field of cloud database to the apparatus control theory. The experiment presented in this article allows the use of the description of the known methods for solving important practical problems.

An Efficient Secure Real-Time Concurrency Control Protocol

Secure real-time databases must simultaneously satisfy two requirements in guaranteeing data security and minimizing the missing deadlines ratio of transactions. However, these two requirements can conflict with each other and achieve one requirement is to sacrifice the other. This paper presents a secure real-time concurrency control protocol based on optimistic method. The concurrency control protocol incorporates security constraints in a real-time optimistic concurrency control protocol and makes a suitable tradeoff between security and real-time requirements by introducing secure influence factor and real-time influence factor. The experimental results show the concurrency control protocol achieves data security without degrading real-time perform ance significantly.

The Organizing of Database from Surlari National Geomagnetic Observatory

Our paper describes the organizing of database,remarks about SNGO(Surlari National Geomagnetic Observatory)and network infrastructure.Based on the geomagnetic data acquired and stored on the database server,we perform the processing and analysis of geomagnetic parameters through different spectral,statistical and correlation methods.All these parameters are included in the geomagnetic database on server.The web interface for the database meets the different needs of handling the data collected,raw or processed.The server-side programming language used for design is php.This allow us to select different periods for which access to stored data,required for different search filters and different parameters or data from different time periods can be compared.For a more in-depth analysis of the stored data,through JavaScript programming language graphs for different parameters can be drawn.Access to the web interface can be done with or without authentication,depending on the need to ensure the security of certain data collected,stored and processed.The applications are scalable for different devices that will access it:mobile,tablets,laptops or desktops.

Study on the relationship between immune cell infiltration pattern and clinical characteristics and prognosis of cervical cancer based on TCGA database

Objective:To investigate the correlation between immune cell infiltration pattern and clinical features and prognosis of cervical carcinoma.Methods:All cervical cancer transcript data and related clinical data were downloaded from the public database Cancer Genome Atlas(TCGA),and the relative proportions of 22 invasive immune cell types were calculated by Cibersort software.Perl was used to assess the correlation between the pattern of immune cell invasion and clinical characteristics(age,clinical stage,tumor grade)in cervical cancer,and the correlation between the pattern of immune cell invasion and survival in cervical cancer was calculated by the K-M Log-Rank method.Result:The distribution of immune cells in 306 cases of cervical cancer and 3 cases of normal tissues was assessed using Cibersort.Compared with normal tissues,the contents of resting dendritic cells,activated dendritic cells,M1 macrophages and activated CD4+memory T cells were higher;the contents of M2 macrophages,neutrophils,regulatory T cells and activated mast cells were lower in cervical cancer tissues.The contents of M1 macrophages,unactivated CD4+memory T cells,andγδT cells were positively correlated with patient age(P<0.05).The contents of follicular helper T cells,activated and unactivated natural killer(NK)cells,and naive CD4 T cells were negatively correlated with patient age(P<0.05).Those with high resting dendritic cell composition had shorter overall survival,while those with high follicular helper T cell composition had longer overall survival(P<0.05).Conclusion:Compared with normal tissues,the composition of immune cells in cervical cancer tissues has certain specificity,which can provide reference for the early screening and diagnosis of the disease.Patients in different age groups may have different immune cell infiltration patterns,which can be used as a basis to explore drug targets in clinical practice.Resting dendritic cells and follicular helper T cells in cervical cancer can be used as possible efficacy predictors of clinical immunotherapy for cervical cancer.

Research on Real-time Data Sharing in Power Integrated Automation System

The Power Integrated Automation System has a large amount of the real-time data, it needs to achieve data sharing in different modules in its own system, sometimes even needs to be shared with the other systems. The thesis discusses the characteristics and the ways of the real-time data sharing in the first place. Then, it compares the merits and drawbacks in different ways. Besides, it gives a viable resolution in different aspects, such as the design of the real-time database, the framework of the communication system and the design of the communication software, as well as the real-time data sharing in different systems.

基于知识图谱的个性化音乐推荐系统设计与实现

本文基于知识图谱技术设计了个性化音乐推荐系统。该系统由用户端、管理端、服务端以及数据库组成。用户完成注册并登录系统后,可以通过输入关键词等方式检索对应的歌曲和歌单,并将其添加收藏,管理员可查看并编辑用户信息。当用户再次登录该系统时,系统会根据之前用户的操作行为向用户精准推送个性化的歌曲和歌单,并在网站主页上显示。从测试情况来看,该系统的音乐推荐、歌曲搜索、歌曲收藏等基本功能可以实现,系统各项操作的平均响应时间均在1 s以内,使用体验较好。

实时数据库数据的批量写入及性能测试研究

通过对石油化工行业使用较多的PHD实时数据库在多模式下的数据批量写入,以标准差指标对测试值进行可信度分析、测试调校,得出多模式下实时数据批量修改、更新测试的最优结果,探索一种行之有效的工业实时数据库优化、应用的方法。

全球矿床数据库建设现状、应用与展望

基于大数据和人工智能技术的数据驱动科学范式推动地球科学研究发生了变革。作为地球科学的重要分支,现代矿床学经历了百余年的发展,已经积累了海量的数据资料,这些数据的流通和共享是发挥其资源价值的关键。文章介绍了中国“地质云”与全球矿产资源储量动态评估数据库、澳大利亚深部地球探测计划AuScope、美国矿产资源在线空间数据库、国际经济地质学家学会(SEG)Geofacets数据库、美国标准普尔公司SNL Metals&Mining数据库等国际主要矿床数据库的情况;同时,列举了应用大数据思维和人工智能方法在区域成矿规律、矿床成因机制、矿床类型判别、资源潜力评价、战略咨询等方面取得的若干重要进展。文章提出,未来在深时数字地球国际大科学计划的平台下,整合全球海量矿床数据,建设开放、共享、统一的矿床大数据平台势在必行。

基于自建数据库的超高效液相色谱-四极杆-飞行时间质谱法定量测定玉米中5种真菌毒素

目的基于自建数据库建立超高效液相色谱-四极杆-飞行时间质谱法(ultra performance liquid chromatography-quadrupole-time-of-flight mass spectrometry,UPLC-Q-TOF/MS)测定玉米中玉米赤霉烯酮(zearalenone,ZEN)、交链孢酚(alternariol,AOH)、交链孢酚单甲醚(alternariol monomethyl ether,AME)、细交链孢菌酮酸(tenuazonic acid,TeA)、腾毒素(tentoxin,TEN)5种负离子真菌毒素的方法。方法样品经提取、净化、复溶后,采用Waters UPLC BEH C18色谱柱进行分离后在信息依赖型的扫描(information-dependent scanning,IDA)负离子模式采集。SCIEX OS Explorer条件下确定5种负离子真菌毒素精确数据录入数据库。在玉米基质中以筛查检出限作为主要参数验证方法。结果高分辨模式下采用加内标来改善基质干扰系数校正,在玉米基体中对真菌毒素类的基质效应θ进行计算,θ在0.84~1.10之间。基质匹配内标校准定量,5种负离子真菌毒素在范围内具有较好的线性关系,相关系数(r)为0.9972~0.9993。5种负离子真菌毒素的检出限为0.2~5.0μg/kg。玉米基质在低、中、高3个加标水平下的平均回收率为83.9%~119.4%,相对标准偏差为2.39%~11.37%(n=6)。用此方法检测内蒙地区120份玉米中5种负离子真菌毒素都有检出,TeA和TEN检出率高达98.1%和95.6%。有3份玉米中ZEN超过100μg/kg限量标准,应引起相关监管部门重视。结论本方法具有高通量、精准、快速等优点,可以在无标准物质情况下对玉米中ZEN、AOH、AME、TeA、TEN的定性筛查,为玉米中这5种真菌毒素污染监测提供技术支持。

时序数据库关键技术综述

随着工业物联网(industrial Internet of things,IIoT)的不断发展,越来越多的设备和传感器开始连接到网络中,产生了大量的时间序列数据(简称“时序数据”),时序数据爆炸式的增长给数据库管理系统带来了新的挑战:持续高吞吐量数据摄取、低延迟多维度数据查询、高性能时间序列索引以及低成本数据存储.近年来时序数据库技术已经成为一个研究热点,一些学者对时序数据库技术进行了深入的研究,同时出现了一些专门用于管理时序数据的时序数据库,并且已经被应用在多个领域,成为工业物联网中不可缺少的关键组成.现有的时序数据库相关综述侧重于时序数据库的功能和性能比较,以及在特定领域中对时序数据库的选择建议,缺少对时序数据库持久化存储、查询、计算和索引等关键技术的研究,同时这些综述工作出现的时间较早,缺少对现代时序数据库关键技术的研究.对学术界时序数据存储研究和工业界时序数据库进行了全面的调查和研究,凝练了时序数据库的4类关键技术:1)时间序列索引优化技术;2)内存数据组织技术;3)高吞吐量数据摄取和低延迟数据查询技术;4)海量历史数据低成本存储技术.同时分析总结了时序数据库评测基准.最后,展望了时序数据库关键技术在未来的发展方向.

卷烟滤棒成型加工区域集控系统实现

针对滤棒成型作业区分散、设备种类多、制造厂家和数量多、接口协议复杂且不统一以及海量数据变量难识别等问题,设计并开发了基于OPC UA架构和实时内存数据库的就地滤棒加工区数采和监控系统。自主开发OPC服务器,实现了滤棒成型主、辅设备的实时数据采集,并通过高效内存数据库服务器对生产及设备信息进行海量存储,进而实现了对滤棒成型车间生产过程信息的全面、准确迁移集成,以及对滤棒生产、产量、质量、机台效率、设备状态等信息的可视化区域集控。