Probabilistic analysis of geomembrane puncture from granular material under liquid pressure

A simplified probabilistic analysis of geomembrane punctures from granular material was presented when subjected to liquid pressure. The probability distribution of contact force between geomembrane and granular material was obtained based on the principle of equal probability and assumptions that grains are spheres with constant size. A particle flow code PFC^3D was employed to simulate the contact process which indicates a good agreement with the theoretical probabilistic analysis. The odds of geomembrane puncture from grains of constant size were obtained by evaluating the puncture force which should not exceed the puncture resistance of geomembrane. The effects of grain radius, grain rigidity and liquid pressure were studied in more detail and displayed in graphs. Both high-level of liquid pressure and large grain can result in high risk of geomembrane puncture. The influence of grain rigidity on the geomembrane puncture odds is significant. For granular material with a grain size distribution, the geomembrane puncture odds can be estimated by the grain size distribution, served as weight function and it is a cautious design if the largest grain is chosen as the design grain size.     

基于潜在主题的分布式视觉检索模型

为将文档聚类划分的分布式检索方法直接应用于视觉检索领域,提出一种基于潜在主题的分布式视觉检索模型。给出模型框架,包括图像视觉单词的数据集划分方法和图像子集选择方法,以此优化图像分布式检索性能。实验结果表明,该模型在不降低检索准确率的前提下,能优先选择少量的图像子集进行检索,并提高查询的吞吐量。     

基于环境要素提取的水上桥梁的定位方法

从高分辨率卫星图像中高效、准确地自动定位描述桥梁目标具有重要的应用价值。本文针对以往检测精度不高,尤其当河水处于枯水期时检测结果依赖检测窗口的选择等问题,从水域提取出发,在桥梁知识模型指导下,经过目标检测和目标定位过程精确定位描述目标。首次引入桥梁阴影特征,通过对它的提取辅助桥梁目标的检测。提取与目标密切相关的环境要素,提出基于环境要素提取的高分辨遥感图像中水上桥梁目标的定位方法,经过环境要素的联合特征提取和知识规则验证,实验验证本文方法提高了定位检测精度。尤其当河水处于枯水期,本文的检测方法优势尤为明显。以实际高分辨率遥感图像为例,实验结果证实了本文方法的有效性。     

基于LabVIEW的疲劳试验机同轴度检测仪设计

针对传统疲劳试验机同轴度检测设备接线繁琐、计算复杂等不足,提出了一种基于LABVIEW的疲劳试验机同轴度检测仪的设计方案,并对该检测仪的硬件和软件设计进行了分析。此检测仪具有低成本、设计灵活、界面友好、应用简单等特点。实践证明该检测仪运行稳定、可靠。     

Infections due to Lancefield group F and related Streptococci (S. milleri, S. anginosus)

We can no longer accept classification of streptococci solely on the basis of hemolytic reactions or Lancefield agglutinations. While the "viridans" streptococci cannot be serologically differentiated, physiological separation of the species offers a satisfactory method of classifying human isolates. We review the microbiology of Lancefield group F and related streptococci (S. milleri, S. anginosus), emphasizing microbial ecology and current taxonomic considerations. A series of 28 patients infected with these organisms is presented. There was a striking male predominance in the series (6:1) as well as an obvious association with underlying diseases and/or antecedent trauma. The most remarkable feature of these pathogens is their predilection for abscess formation, confirming their overdue recognition as the most common "viridans" streptococcus recovered from abscesses within internal organs. We observed purulent disease of the nervous and skeletal systems, oral cavity, lung and pleural space, abdomen and subcutaneous tissues. Microbial synergy (i.e. polymicrobic infection) was not a requisite for abscess formation. Four of the five deaths in this series occurred in patients 60 years of age of older. Some degree of variability in antimicrobial susceptibility was noted, so speciation alone may not always provide sufficient information on which to base a therapeutic decision.     

一种快捷的LDPC码编码方法

LDPC码作为一种性能优异的纠错码，已经越来越引起通信领域的研究兴趣。而LDPC码性能的优劣，与其二分图中是否存在短长度的圈有关，也即与其奇偶校验矩阵的构造有关。本文在扩展比特填充算法的基础上，设计出一种能够直接编码的奇偶校验矩阵，并在不同码长的情况下进行了仿真，结果表明采用这种设计方法构造的LDPC码随机分布性好，不需要复杂的矩阵求逆，从而对LDPC码的实际应用具有重要参考价值。     

基于证据理论的常规导弹阵地生存防护研究

着眼于阵地生存防护时策分析中的不确定性，提出了一种基于证据理论判别来袭武器类型的方法，通过对武器威胁度的评估，建立了来袭武器威胁等级判据，构建了详细的生存对策，可为常规导弹阵地生存防护决策提供有效的辅助支持．     

非英语专业男女大学生英语学习差异对比

运用定量研究的方法,通过问卷和访谈方式,对非英语专业男女大学生的学习风格、词汇学习策略和英语学习策略进行了调查和分析.结果表明：男女生在学习风格、词汇学习策略和英语学习策略上存在一些较大差异.     

基于FPGA的超高速FFT硬件实现

介绍了频域抽取基二快速傅里叶运算的基本原理;讨论了基于FPGA达4 096点的大点数超高速FFT硬件系统设计与实现方法,当多组大点数进行FFT运算时,利用FPGA内部大容量存储资源,采用乒乓结构进行流型运算,提高FFT运算速度,同时保证结果的准确性;对实际硬件进行了FFT运算测试,测试结果证明了系统的可行性和正确性,并且利用该硬件系统成功完成了星载SAR实时成像处理。