149 research outputs found

    Design and Implementation of Smartphone Bus Information Query System Based on Android Platform

    Get PDF
    随着我国城市化经济的飞速发展,公共交通在这一进程中的作用越来越重要。目前, 我国城市公共交通的线路和站点越来越多,逐渐形成了一个复杂的公共交通网络。然而, 正是因为公交网络的复杂,导致人们无法快速选择合适的公交线路。因此需要一个公交查 询系统来帮助公交乘客快速选择适合出行需求的路线,以节约时间及费用成本。目前虽然 已经存在一些公交信息查询系统,但大多数需要通过电脑网页来查询,用户体验方面还不 是特别优秀。国内手机普及率几乎达到100%,因此开发出一款基于智能手机的公交信息查 询系统,对公交乘客来说可用度非常高。 论文调研了目前手机应用程序和公交信息查询的系统,发现这些公交信息查询...With the rapid development of urbanization in China, the role of public transport in this process is becoming more and more important. At present, the number of city public transportation lines and the stations is growing rapidly, and is gradually becoming a complex public transport network. However, precisely because of the complexity of the public transport network, people can not choose the...学位:工程硕士院系专业:软件学院_工程硕士(软件工程)学号:X201323174

    @@

    Get PDF
    中药是我国传统医学的重要组成部分,但部分中药存在成分复杂、水溶性差等问题,给临床前研究,尤其是体外药效学研究带来困扰。本文就目前体外药效学研究中难溶性中药或中药成分增溶方法或技术进行综述,探讨其可行性及对中药药效行为的影响。福建省自然科学基金项目(2015J01491

    Research on Materialized View Selection

    Get PDF
    定义了数据仓库领域的视图选择问题,并讨论了与该问题相关的代价模型、收益函数、代价计算、约束条件和视图索引等内容;介绍了3大类视图选择方法,即静态方法、动态方法和混合方法,以及各类方法的代表性研究成果;最后展望未来的研究方向.Definition of view selection issue in the field of data warehouses is presented, followed by the discussion of related problems, such as cost model, benefit function, cost computation, restriction condition, view index, etc. Then three categories of view selection methods, namely, static, dynamic and hybrid methods are discussed. For each method, some representative work is introduced. Finally some future trends in this area are discussed.Supported by the National Natural Science Foundation of China under Grant No.60473051 (国家自然科学基金); the National High-Tech Research and Development Plan of China under Grant Nos.2007AA01Z191, 2006AA01Z230 (国家高技术研究发展计划(863)

    Change Data Capture in Real-Time Active Data Warehouses: A Survey

    Get PDF
    本文是在北京大学数据库实验室攻读博士学位期间发表的。实时主动数据仓库是数据仓库的最新发展阶段和未来发展趋势,它为企业提供了对战略决策和战术决策的双重支持.实时主动数据仓库中包含两类数据,即实时数据和非实时数据,相应地,需要两种不同类型的变化数据捕捉方法,即支持实时变化数据捕捉的方法和普通的(不支持实时的)变化数据捕捉方法.结合在该领域的研究经验,对实时主动数据仓库中可以使用的多种变化数据捕捉方法进行了系统地论述,并比较各种方法的应用条件、优点、缺点和适用场合。Real-time active data warehouse is the most recent stage in the evolution history of data warehouses.It supports both strategic decision and tactic decision,which will bring great benefits to organizations.There are two types of data existing in real-time active data warehouses,i.e.,real-time data and non-real-time data.Accordingly,change data capture methods are classified into tWO kinds,including those supporting real-time change data capture and those not supporting real-time change data capture.Based on extensive research work in this field,those change data capture methods are systematically discussed,which may meet the requirements in real-time active data warehouses.国家自然科学基金项目(60473015);国家“863”高技术研究发展计划基金项目(2006AAl2Z217);HP中国实验室联合项

    Research on Requirement-based Real-time Data Integration in Real-time Active Data Warehouses

    Get PDF
    本文是在北京大学数据库实验室攻读博士学位期间发表的。实时数据集成是实时主动数据仓库研究领域的一个重要问题。现有的研究成果都是从技术角度出发,而并没有考虑具体的商务应用需求。而在大型商务应用中,即使采用过滤规则只捕捉感兴趣的变化数据,也会产生大量的数据集成工作,从而导致不必要的沉重系统开销,同时还很有可能出现系统响应缓慢和用户需求无法得到满足等情况。本文从应用角度出发,提出了实时主动数据仓库中面向需求的实时数据集成方法,包括被频繁请求的数据的实时集成、满足突发请求的实时数据集成和由用户决定的实时数据集成。针对不同的商务需求,采用不同的数据集成策略,可以很好地满足不同类型的应用需求。Real-time data integration is a very important aspect in the field of real-time active data warehouse. Almost all the available research work now is from a technological point of view instead of an application angle. While in the real-world business application, a large amount of real-time data integration needs to be done even with the help of change data capture technology to integrate only the interesting part of the data from the data source, which will usually lead to the deteriorated system performance and fail to satisfy the business requirement in some cases. From an application angle, we here propose three requirement-based real-time data integration methods, including: real-time integration for the frequently requested data, real-time integration for the suddenly arising requirement and user-decided real-time integration. By adopting the appropriate method for the specific application occasion, we can better satisfy the various business requirements.国家自然科学基金项目(60473015);国家“863”高技术研究发展计划基金项目(2006AAl2Z217);HP中国实验室联合项

    Spectrum-effect relationship of immunosuppressive activity of Leigongteng Duogan Tablet based on partial least squares regression analysis

    Get PDF
    目的初步探讨雷公藤多苷片免疫抑制作用及其HPlC指纹图谱间的相关性。方法采用HPlC建立7个厂家生产的雷公藤多苷片醋酸乙酯提取物的指纹图谱,选择刀豆蛋白A(COn A)刺激的小鼠脾淋巴细胞模型进行免疫抑制药效学研究,分别考察雷公藤多苷片对小鼠脾淋巴细胞增殖以及细胞因子γ干扰素(Ifn-γ)分泌的影响;采用偏最小二乘回归分析法分析谱效关系。结果建立了7个厂家生产的雷公藤多苷片的HPlC指纹图谱,从HPlC指纹图谱中提取出18个能够表征差异的特征峰。药效研究结果显示不同厂家生产的雷公藤多苷片均可显著抑制COn A诱导的小鼠脾淋巴细胞增殖和Ifn-γ的分泌(P<0.05)。偏最小二乘回归法分析结果显示,以抑制小鼠脾淋巴细胞增殖IC50值为药效指标时第1、2、6、7、17、18号峰为药效峰;以Ifn-γ分泌抑制率为指标时,第1、2、6、7、8、9、12、13号峰为药效峰。结论第1、2、6、7、8、9、12、13、17、18号峰所代表的化合物可能为雷公藤多苷片中发挥免疫抑制主要有效成分。Objective To investigate the immunosuppressive components in Leigongteng Duogan Tablet(LDT).Methods High performance liquid chromatography(HPLC) was applied to establish the fingerprint for LDT from seven manufactures.The immunosuppressive effect of LDT was observed on Con A-induced mice spleen cells, and the cell proliferation and contents of IFN-γ were recorded.Then the partial least squares regression(PLSR) analysis was used to investigate its spectrum-effect relationship.Results The HPLC fingerprint for LDT from seven manufactures was established, and 18 characteristic peaks were confirmed.The in vitro cell experimental results showed that the proliferation of mice spleen cells and secretion of IFN-γ were inhibited by all LDT significantly compared with the control group.According to the results of PLSR, No.1, 2, 6, 7, 17, and 18 peaks were strongly related to the proliferation inhibition of mice spleen cells and No.1, 2, 6, 7, 8, 9, 12, and 13 peaks were related to the secretion of IFN-γ.Conclusion The No.1, 2, 6, 7, 8, 9, 12, 13, 17, and 18 peaks are the principal immunosuppressive substances in LDT.福建省科技计划重大项目(2012I1001

    Materialized Views Selection of Multi-Dimensional Data in Real-Time Active Data Warehouses

    Get PDF
    通过基于主动决策引擎日志的数据挖掘来找到分析规则的CUBE 使用模式,从而为多维数据实视图选择算法提供重要依据;在此基础上设计了3A 概率模型,并给出考虑CUBE 受访概率分布的视图选择贪婪算法PGreedy(probability greedy), 以及结合视图挽留原则的视图动态调整算法. 实验结果表明, 在实时主动数据仓库环境下,PGreedy 算法比BPUS(benefit per unit space)算法具有更好的性能. In this paper, data mining based on the log of active decision engine is introduced to find the CUBE using pattern of analysis rules, which can be used as important reference information for materialized views selection. Based on it, a 3A probability model is designed, and the greedy algorithm, called PGreedy (probability greedy), is proposed, which takes into account the probability distribution of CUBE. Also view keeping rule is adopted to achieve better performance for dynamic view adjusting. Experimental results show that PGreedy algorithm can achieve better performance than BPUS (benefit per unit space) algorithm in real-time active data warehouses environment.Supported by the National Natural Science Foundation of China under Grant No.60473051 (国家自然科学基金); the China HP Co. and Peking University Joint Project (北京大学-惠普(中国)合作项目

    镍盐前驱体对Ni/C催化剂乙醇气相羰化活性的影响

    Get PDF
    采用等体积浸渍法制备了分别以乙酰丙酮镍、氯化镍、硝酸镍和醋酸镍为前驱体负载在活性炭上的4种催化剂。用BET、金属分散度、H2程序升温还原(H2-TPR)、CO-程序升温脱附(CO-TPD)和XRD等测试技术研究了4种催化剂的结构特点和乙醇气相羰化活性。结果表明,以醋酸镍制备的Ni/C催化剂的羰化活性最高,乙醇转化率和丙酸选择性分别为96.1%和95.7%,而以乙酰丙酮镍制备的Ni/C催化剂的羰化活性最低,乙醇转化率和丙酸选择性分别为68.9%和27.1%。这种活性的差异与镍盐前驱体和活性炭之间的相互作用强弱有着密切关系。醋酸镍组分与活性炭之间的相互作用较强,浸渍组分易在活性炭表面充分吸附,活性中心Ni0在240~340℃温度范围内对CO吸附量最大,还原后金属镍的分散度较好且晶粒较小

    Ni-M(M=Cu,Zn,Ce)/C双金属催化剂上的乙醇气相羰化

    Get PDF
    利用等体积浸渍法制备了NiM0.2(M=Cu,Zn,Ce)/C双金属催化剂及Ni/C催化剂,考察了其乙醇气相羰化制丙酸的活性。结果表明,4种催化剂的活性大小顺序为NiCe0.2/C>Ni/C>NiCu0.2/C>NiZn0.2/C,催化剂NiCe0.2/C的羰化活性最高,乙醇转化率和丙酸的选择性分别为98.0%和95.1%,而催化剂NiZn0.2/C的羰化活性最低,乙醇转化率和丙酸选择性分别为83.6%和75.8%。通过对催化剂的金属分散度、XRD、H2-TPR和CO-TPD等表征结果的分析,发现CeO2与镍物种之间存在协同作用,从而降低NiO的还原温度,有效防止镍晶粒的长大,并提高了镍物种在活性炭表面的分散度

    制备因素对Ni/C催化剂上乙醇气相羰基化反应性能的影响

    Get PDF
    采用等体积浸渍法制备负载型Ni/C催化剂,考察了制备因素对乙醇直接气相羰基化反应的影响。实验结果表明,催化剂最佳制备因素为,Ni的质量分数为5%,活性炭采用水洗预处理,控制浸渍液的pH值为8.0~9.0,焙烧温度为450℃,H2还原温度为400℃。采用上述参数制备的Ni/C催化剂,其乙醇转化率和丙酸选择性分别为96.14%和95.71%。利用N2物理吸附法研究载体预处理对催化剂比表面积、孔容及孔径的影响和X射线衍射法(XRD)研究了活性组分在惰性气氛中焙烧时的分散状况
    corecore