双级贯流式水轮机导叶和转轮的水力设计

针对一种新型双级贯流式水轮机,推导了一级导叶、一级转轮、二级导叶和二级转轮的参数设计公式。利用数值模拟商业软件Fluent分析了水轮机在设计工况下的数值性能。数值计算时控制方程采用雷诺时均N-S离散方程,湍流模型选择标准k-ε模型,得到了水轮机的流线图、导叶和转轮叶片的压力面和吸力面的压力分布图,以及中心对称面x=0.083 5的速度矢量图,数值计算结果证明了水轮机设计的正确性。     

基于SMW工法的城市深基坑开挖稳定性分析

SMW工法具有防渗性好、构造简单、施工速度快、工程造价低等优点,广泛应用于大型隧道工程、城市地下空间开发、高层建筑深基坑开挖支护工程等。以某城市深基坑工程的SMW工法围护结构为研究对象,在考虑水泥土与型钢的相互作用下,建立有限元数值模型,分析开挖过程中墙体位移和土体变形特点。结果表明:开挖深度对墙体侧向位移有显著影响;随着坡面荷载的增加,基坑内外水平方向和竖直方向沉降量均有所增大。     

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.     

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。     

Mixed Methods Research Designs in Counseling Psychology.

With the increased popularity of qualitative research, researchers in counseling psychology are expanding their methodologies to include mixed methods designs. These designs involve the collection, analysis, and integration of quantitative and qualitative data in a single or multiphase study. This article presents an overview of mixed methods research designs. It defines mixed methods research, discusses its origins and philosophical basis, advances steps and procedures used in these designs, and identifies 6 different types of designs. Important design features are illustrated using studies published in the counseling literature. Finally, the article ends with recommendations for designing, implementing, and reporting mixed methods studies in the literature and for discussing their viability and continued usefulness in the field of counseling psychology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Charging and Spin Effects in Triple Dot Artificial Molecules

We have fabricated artificial molecules consisting of three coupled quantum dots defined in the two-dimensional electron gas of a GaAs/AlGaAs heterostructure using lithographically patterned gates and trenches. The three dots are arranged in a ring structure, where each dot is coupled to the other two dots. We find that, when tuned to the Coulomb blockade regime, the triple quantum dot device acts as a charge rectifier: an electron enters the third dot where it is trapped, producing a jamming effect where no other electron may enter the first dot. Triple quantum dots coupled in a ring will allow for the study of new molecular phases using artificial molecules and may also serve as building blocks of two-dimensional arrays for quantum computation.     

Fault arcs effects in cable bundles for space applications invacuum

A multitude of `arc tracking' tests on cables for space applications has been performed to improve the basic understanding of the phenomena responsible for the fault arc behavior. The damage in a cable bundle develops in a complex system consisting of metallic conductors, insulation materials and arc plasma. Considering the degradation effects, vacuum as one of the applied test parameters, has turned out to be an important test environment. The investigations are based on a new test method, developed to assess arc tracking properties of cables for space applications. Tests were conducted with different insulation materials at cables with different AWG at 125 V dc and nominal currents. The tests were focused on the vacuum environment, using air only for the purpose of comparison. For some cable types, vacuum has turned out to be a worst-case environmental condition with respect to fault arc effects, such as the conductor burn-off, degradation of the insulation of adjacent cables and the extension of the fault arc. This paper presents these worst case experiments in detail     

A flexible and recoverable client/server database event notification system

A software architecture is presented that allows client application programs to interact with a DBMS server in a flexible and powerful way, using either direct, volatile messages, or messages sent via recoverable queues. Normal requests from clients to the server and replies from the server to clients can be transmitted using direct or recoverable messages. In addition, an application event notification mechanism is provided, whereby client applications running anywhere on the network can register for events, and when those events are raised, the clients are notified. A novel parameter passing mechanism allows a set of tuples to be included in an event notification. The event mechanism is particularly useful in an active DBMS, where events can be raised by triggers to signal running application programs. Received July 21, 1995 / Accepted May 30, 1996     

Robocup小型足球机器人AI决策系统设计--Robocup系列研究之六

介绍了Robocup小型足球机器人的AI决策系统的分层式结构设计方案。重点阐述了信息处理层的设计，采用扩展卡尔曼滤波(EKF)对场上所有对象进行跟踪和预测，并介绍了责任区域划分和按责任区域划分决定战术决策选择的思想，通过对基本信息的处理运算建立了实时更新的信息库，为后续战术策略选择提供了信息和依据，     

Keeping smart, omnidirectional eyes on you [adaptive panoramic stereovision]

An adaptive panoramic stereo approach for two cooperative mobile platform is presented. There are four key features in the approach: 1) omnidirectional stereovision with an appropriate vertical FOV, and a simple camera calibration method; 2) cooperative mobile platforms for mutual dynamic calibration and best view planning; 3) 3D matching after meaningful object (human subject) extraction; and 4) real-time performance. The integration of omnidirectional vision with mutual awareness and dynamic calibration strategies allows intelligent cooperation between visual agents. This provides an effective way to solve the problems of limited resources, view planning, occlusion, and motion detection of movable robotic platforms. Experiments have shown that this approach is quite promising.