Empirical assessment of a threshold model for sylvatic plague.

Plague surveillance programmes established in Kazakhstan, Central Asia, during the previous century, have generated large plague archives that have been used to parameterize an abundance threshold model for sylvatic plague in great gerbil (Rhombomys opimus) populations. Here, we assess the model using additional data from the same archives. Throughout the focus, population levels above the threshold were a necessary condition for an epizootic to occur. However, there were large numbers of occasions when an epizootic was not observed even though great gerbils were, and had been, abundant. We examine six hypotheses that could explain the resulting false positive predictions, namely (i) including end-of-outbreak data erroneously lowers the estimated threshold, (ii) too few gerbils were tested, (iii) plague becomes locally extinct, (iv) the abundance of fleas was too low, (v) the climate was unfavourable, and (vi) a high proportion of gerbils were resistant. Of these, separate thresholds, fleas and climate received some support but accounted for few false positives and can be disregarded as serious omissions from the model. Small sample size and local extinction received strong support and can account for most of the false positives. Host resistance received no support here but should be subject to more direct experimental testing.     

水平管路清管过程流动参数变化规律模拟研究

混输管路清管技术的研究对混输管道的运行管理具有非常重要的意义。在分析清管器清管物理模型的基础上 ,建立清管器的特征参数计算模型、动态数学模型和数值计算方法 ,并进行数值模拟 ,计算出测压点压力随时间变化的数据 ,并把它们与试验数据进行比较 ,得到清管过程中压力的变化规律。通过数学模拟 ,可以计算清管过程中管道的压力分布状况 ,利用压力分布状况就可跟踪清管球在管道内的运行情况     

A unified framework of opening and closure operators with respect to arbitrary fuzzy relations

 This paper is devoted to a general concept of openness and closedness with respect to arbitrary fuzzy relations – along with appropriate opening and closure operators. It is shown that the proposed framework unifies existing concepts, in particular, the one for fuzzy preorderings as well as the triangular norm-based approach to fuzzy mathematical morphology. The author acknowledges support of the K _plus Competence Center Program which is funded by the Austrian Government, the Province of Upper Austria, and the Chamber of Commerce of Upper Austria.     

电加热井的井筒温度场数学模型

运用传热学理论，通过对稠油从井底流出井筒的温度变化、井筒原油与地层之间热交换过程的传热机理研究，建立数学模型，可以模拟不同产量、不同含水的井筒温度剖面，以及电加热所需功率，从而为稠油井电加热生产方案的制定提供科学依据。     

高含沙量岛屿海域工程建设的潮动力沉积影响研究

以高含沙量岛屿海域洋山海区为例,采用平面二维有限元数学模型模拟了该区域的流场。计算了修筑防波堤后海域底床的泥沙冲淤变化。结果表明,影响仅限于工程附近。     

重金属污染物动态吸附试验及数学模拟

本文采用泥沙动力学中Ｒｏｕｓｅ等人用来研究泥沙浓度沿垂线分布的装置。对泥沙吸附重金属污染物进行了动态模拟。试验分有底泥和无底泥两种情况。研究中发现在Ｒｏｕｓｅ装置的水力、泥沙条件下泥沙吸附重金属污染物达到平衡状态需要６小时以上，由极坐标下的重金属迁移转化数学模型方程，在本文具体试验条件下进行数值求解，计算结果和试验结果合良好，说明数学模型是正确合理的试验是可靠的。计算时依据室内静态试验结果，对动态     

形态学边缘检测的新算法及其应用

提出了一种基于数学形态学的边缘检测的所算法，该算法具有简便和灵活可编程控制等优点，比原来主算法更国完善，在实际应用中有着很好的前景，并给出了实验结果。     

多目标水平井水平段三维设计数学模型

用柱面法推导出多目标水平井水平段三维设计数学模型，并给出了三维设计所需井斜方位角及井斜角的简单计算公式。该数学模型具有一般性，可以方便地编制成计算机程序，对于多目标水平井水平段的优化设计和所有水平井入靶前的随钻修正设计都非常适用。     

大庆油田深层岩石力学特性参数的试验研究

通过对岩石可钻性、硬度、抗压强度等参数的测量 ,对大庆油田深井不同深度、不同层位、不同岩性的具有广泛代表性的岩心进行试验。并通过线性回归分析 ,建立了适用性较广的钻井岩石力学特性参数预测模型 ,为深井钻头选型提供了依据。