组合分布在超定量洪水系列频率分析中的应用研究

研究了估计超定量洪水年发生次数的泊松分布和二项分布，并将这两种分布分别与指数分布组合，模拟超定量洪水系列．推导出丁年重现期洪水估计的计算公式。实例计算结果表明，二项分布拟合超定量洪水年发生次数的效果优于泊松分布，建议采用二项分布和指数分布组合进行年最大超定量洪水系列频率分析。     

聚对苯二甲酰癸二胺的合成与表征

由对苯二甲酸癸二胺盐合成了高特性黏数的聚对苯二甲酰癸二胺(PA10T),用傅里叶变换红外光谱(FTIR)、核磁共振和示差扫描量热仪对预聚中间产物和最终产物进行了表征,用凝胶渗透色谱测定 PA10T 聚合物的相对分子质量及其分布,并通过加入第三单体对 PA10T 进行共聚改性。表征结果显示,所合成的聚合物为 PA10T,预聚中间产物的 FTIR 谱图中含有对苯二甲酸癸二胺盐和 PA10T 的特征吸收峰;PA10T 出现了熔融双峰的现象,经增黏后的 PA10T 的熔点比 PA10T 预聚物的熔点有很大幅度的提高;经共聚改性后的 PA10T 共聚物的熔点、结晶温度和熔融热明显降低。     

Assessment of ‘peaks over threshold’ methods for estimating extreme value distribution tails

In the past twenty years a vast new body of extreme value theory was developed, referred to as ‘peaks over threshold modeling.’ This theory allows the use in the analysis of all data exceeding a sufficiently high threshold, a feature that may result in improved extreme value estimates. The application of the theory depends upon the performance of methods for estimating the distribution parameters corresponding to any given set of extreme data. We present a comparative assessment of the performance of three such methods. The assessment is based on Monte Carlo simulations from populations with four distributions: Gumbel, Weibull, generalized Pareto, and normal. The simulation results showed that the de Haan and the Conditional Mean Exceedance (CME) methods performed consistently better than the Pickands method (NIST implementation). For the distributions, parameter values, and mean recurrence intervals assumed in this work, the CME method outperformed the de Haan method only when the percent estimation errors were about one percent or smaller, a case unlikely to be encountered in wind engineering practice.     

基于局部密度的最小生成树聚类算法及其在电力大数据的应用

电力大数据主要来源于电力生产和电能使用的发电、输电、变电、配电、用电和调度各个环节,,如何运用这些数据提高电力管理工作的智能化水平已经成为相关电力环节十分重要的研究课题之一。但现有电力大数据中用到的聚类方法却不能发现任意形状的数据集聚类类别(即类簇),这影响了电力大数据在应用中的计算精度与计算时长。因此提出了一种新的算法,即使用局部密度峰值和基于共享邻点的距离,更好地结合了密度与距离的关系,表示出数据之间的差异。使用局部密度峰值并用基于共享邻点的距离来构造最小生成树,然后重复切割最长的边,直到找到给定数量的簇。在电力大数据应用上的实验结果表明,该算法在具有良好的效果。     

多元检测线圈在石油拼接套管的远场涡流检测中的应用

在基于远场涡流的拼接套管检测中,拼接套管各管道分析的复杂性会因为远场涡流两次穿透套管壁的特性而增加.当发射线圈处于缺陷位置时,作者已提出基于双接收线圈的伪峰移除方法.当发射线圈处于正常管道位置时,伪峰移除方法并不能移除检测信号中发射线圈处管道的信息,所以本文提出弥补该不足点的方法.该方法首先通过去伪峰方法将检测信号中发射线圈附近的管道情况统一转化为无缺陷的情况;然后,采用维纳去卷积滤波器获取拼接套管上缺陷（接箍可视为缺陷）的位置信息,并根据缺陷位置反向定位拼接套管正常位置.最后,统一移除检测信号中发射线圈处管道的信息.该方法通过仪器测试科索#1井得到验证,有利于提高远场涡流在拼接套管检测分析中的实用性.     

PA6-PEG多嵌段共聚物的结构和性能——Ⅱ.嵌段共聚物的结晶度和晶粒尺寸

应用大角 X 射线衍射法测出了一系列聚己内酰胺(PA6)—聚乙二醇(PEG)嵌段共聚物的结晶衍射图谱.利用计算机对该图谱进行分峰,得到数学上符合δ≤5%的精度,物理意义上符合客观存在的解.在此基础上,估算了 PA6-PEG 嵌段共聚物的结晶度和表观晶粒尺寸,比较了相同组分的共聚物和共混物在晶态结构上的差异,分析了相同处理条件下共聚物组成比的变化对各种晶型生长的影响,以及由此产生的对聚合物性质的影响.     

三维方管层流冲击射流流动与传热的数值研究

通过求解三维稳态不可压缩N-S方程和能量方程,对半封闭层流方管冲击射流的流动与传热特性进行了数值研究。根据计算结果分析了射流中四个偏心速度峰值形成的原因,在层流范围内考察了射流雷诺数和冲击高度对流场结构和传热性能的影响。计算结果表明,冲击射流的传热特性受流场结构的控制,冲击面附近水平断面上四个偏心速度峰值的形成,导致在相应断面上形成温度分布的四个偏心最小值,以及在冲击面上形成局部Nu数的四个偏心峰值。     

辉光放电质谱法中干扰峰的分析研究

As a direct solid sampling technique, glow discharge mass spectrometry(GD-MS) has been widely applied to the trace and ultra trace element analysis of conductors and semi-conductors. By the use of various kinds of the information of the interferences in the analyzing solid sample, combining with the working principle of GD-MS. we analyzed and recognized matrix in the tested sample messages to obtain more complete sample signals and more reliable analyzing results.     

An iterative two‐step sequential phase partition (ITSPP) method for batch process modeling and online monitoring

Operating at different manufacturing steps, multiphase modeling and analysis of the batch process are advantageous to improving monitoring performance and understanding manufacturing processes. Although many phase partition algorithms have been proposed, they have some disadvantages and cause problems: (1) time sequence disorder, which requires elaborate post‐treatments; (2) a lack of quantitative index to indicate transition patterns; and (3) tunable parameters that cannot be quantitatively determined. To effectively overcome these problems, an iterative two‐step sequential phase partition algorithm is proposed in the present work. In the first step, initial phase partition results are obtained by checking changes of the control limit of squared prediction error. Sequentially, the fast search and find of density peaks clustering algorithm is employed to adjust the degradation degree and update the phase partition results. These two steps are iteratively executed until a proper degradation degree is found for the first phase. Then, the remaining phases are processed one by one using the same procedure. Moreover, a statistical index is quantitatively defined based on density and distance analysis to judge whether a process has transitions, and when the transition regions begin and end. In this way, the phases and transition patterns are quantitatively determined without ambiguity from the perspective of monitoring performance. The effectiveness of the proposed method is illustrated by a numerical example and a typical industrial case. Several typical phase partition algorithms are also employed for comprehensive comparisons with the proposed method. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2358–2373, 2016     

Face perception in high-functioning autistic adults: Evidence for superior processing of face parts, not for a configural face-processing deficit.

Configural processing in autism was studied in Experiment 1 by using the face inversion effect. A normal inversion effect was observed in the participants with autism, suggesting intact configural face processing. A priming paradigm using partial or complete faces served in Experiment 2 to assess both local and configural face processing. Overall, normal priming effects were found in participants with autism, irrespective of whether the partial face primes were intuitive face parts (i.e., eyes, nose, etc.) or arbitrary segments. An exception, however, was that participants with autism showed magnified priming with single face parts relative to typically developing control participants. The present findings argue for intact configural processing in autism along with an enhanced processing for individual face parts. The face-processing peculiarities known to characterize autism are discussed on the basis of these results and past congruent results with nonsocial stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)