采用约束最小平方和法实现近场波束形成

本文研究了近场情况下的波束形成问题。对于任意结构阵列,提出了实现近场波束形成的一种约束最小平方和法,由近场信号模型来设计近场波束。该方法在对波束旁瓣施加约束的条件下,使波束主瓣的误差平方和最小,可借助于优化工具箱实现。该方法在主瓣区域和旁瓣区域都能得到满足设计要求的波束性能,不仅可以方便地控制期望响应,而且简单易行。基于32元均匀离散圆阵的仿真设计结果表明了本文方法的有效性。     

海洋噪声背景下基于随机共振方法的波束形成

为了改善低信噪比下波束形成的性能,从双稳态随机共振模型出发,提出了利用频率尺度变换,将随机共振和波束形成结合起来的算法。给出了双稳态模型参数的估计方法、数值仿真和应用于海洋噪声背景下波束形成的实验结果。由实验结果可见,随机共振确实改善了波束形成器输入数据的质量,从而提高了波束形成的性能以及信噪比。     

身体构成与有氧耐力的相关性对选飞的意义

分析身体构成影响有氧耐力的机理,探讨其相关性在飞行员筛选中的意义,得出脂肪重量与有氧耐力有一定相关性,但不能单独作为预测有氧耐力的因素。还需与瘦体重相结合;应建立不同年龄、不同机种的脂肪百分比标准,对飞行人员进行筛选;用科学的锻炼方法,膳食标准来改善飞行员的身体攀构成比例及有氧耐力水平。     

近场波束形成的约束最小平方和法

文章研究了近场情况下的波束形成问题。对于任意结构阵列,提出了近场波束形成的一种约束最小平方和法,用近场信号模型来设计近场波束。该方法借助于优化工具箱,在对波束旁瓣施加约束的条件下,使波束主瓣的误差平方和最小。该方法在主瓣区域和旁瓣区域都能得到满足设计要求的波束性能,可以方便地控制期望响应,简单易行。基于32元均匀离散圆阵的仿真设计结果表明了文中方法的有效性。     

A review on strategic capacity planning for the semiconductor manufacturing industry

Due to the high capital investment cost in the semiconductor manufacturing industry, strategic capacity planning plays an important role in improving business performance. The reasons that make these problems especially difficult are: the complex fabrication process, rapid changes in technology and products, the long lead time and the high cost of capacity increment, and the high uncertain demand and capacity. Hence, a review of the existing solutions to capacity planning to cope with these difficulties is important for developing new methodologies and practices. In this paper, we provide a review of the current research and fundamental methods in strategic capacity planning, identify emerging methods for capacity planning, and take an in-depth look at future research interests.     

Technical Flaw Detection Based on a New Image Recognition Theory

An algorithm is considered for constructing a system of technical flaw detection of welded joints. An image recognition theory based on stochastic geometry is the foundation of the algorithm. Basing the recognition on a large number of image tags allows for more problems to be solved, including those with multiple structure classes.     

基于深度学习的超声成像技术研究现状

超声成像技术以其无损、无辐射、实时性好、成像深度深和检查费用低等优点,是目前临床医学最常应用的影像技术之一。随着医疗技术的日益发展,兼顾高帧率和高质量的超声成像已成为临床上的迫切需求。深度学习作为能快速提取信号特征的技术,近年来已经在超声成像领域展开多种应用研究并产生了较好的效果,具有很大的应用前景。文章总结了基于深度学习的超声成像技术现状,重点介绍了超声成像技术中常用深度学习架构,列举了深度学习技术在超声成像中的应用,最后总结了目前深度学习在训练以及实现临床应用中可能会遇到的挑战。     

Biological Microobject Analysis by Stochastic Geometry Methods

Stochastic geometry is applied to the analysis of DNA chains and soft measurement of their lengths.     

网络时代的三大基本定律与骨干网容量的演进

文章首先分析了新时期的巨大挑战及其对网络的深远影响,特别指出了网络面临的巨大容量压力。接下来分别就主宰网络时代的三个基本定律：摩尔定律、光纤定律和迈特卡尔夫定律的内涵、影响和技术极限进行了论述。最后探讨了骨干网传输链路、传送节点和业务节点的容量演进策略。     

冷冻除湿机最优风量的试验分析

在名义工况下,对调温型除湿机的样机在水冷降温模式和一般升温模式下进行测试,分析风量对制冷量（或制热量）、除湿量、修正输入功率及单位输入功率除湿量的影响,认为存在一个最优风量（4 000m3/h）使得冷冻除湿机单位输入功率除湿量最大.     

Ordering structured populations in multiplayer cooperation games

Spatial structure greatly affects the evolution of cooperation. While in two-player games the condition for cooperation to evolve depends on a single structure coefficient, in multiplayer games the condition might depend on several structure coefficients, making it difficult to compare different population structures. We propose a solution to this issue by introducing two simple ways of ordering population structures: the containment order and the volume order. If population structure is greater than population structure in the containment or the volume order, then can be considered a stronger promoter of cooperation. We provide conditions for establishing the containment order, give general results on the volume order, and illustrate our theory by comparing different models of spatial games and associated update rules. Our results hold for a large class of population structures and can be easily applied to specific cases once the structure coefficients have been calculated or estimated.     

多波束融合BP神经网络拖船噪声抵消

拖曳线列阵声纳中,拖船噪声常常是影响声纳性能的重要因素之一。由于存在严重的多途效应,仅仅改变自适应结构难以提高拖船噪声抵消性能。因此在实际应用中,固定参考输入自适应干扰抵消技术的抵消效果一般均不理想,本文针对拖船噪声的特性,提出了一种多干扰波束融合的抵消算法,该算法具有抗多途效应效果好,可以较有效地消除拖船干扰,提高声纳的检测性能,试验数据处理结果表明它优于现有的自适应方法,且具有运算量少的优点,可望在实际声纳中得到应用。     

eXtended Stochastic Finite Element Method for the numerical simulation of heterogeneous materials with random material interfaces

An eXtended Stochastic Finite Element Method has been recently proposed for the numerical solution of partial differential equations defined on random domains. This method is based on a marriage between the eXtended Finite Element Method and spectral stochastic methods. In this article, we propose an extension of this method for the numerical simulation of random multi‐phased materials. The random geometry of material interfaces is described implicitly by using random level set functions. A fixed deterministic finite element mesh, which is not conforming to the random interfaces, is then introduced in order to approximate the geometry and the solution. Classical spectral stochastic finite element approximation spaces are not able to capture the irregularities of the solution field with respect to spatial and stochastic variables, which leads to a deterioration of the accuracy and convergence properties of the approximate solution. In order to recover optimal convergence properties of the approximation, we propose an extension of the partition of unity method to the spectral stochastic framework. This technique allows the enrichment of approximation spaces with suitable functions based on an a priori knowledge of the irregularities in the solution. Numerical examples illustrate the efficiency of the proposed method and demonstrate the relevance of the enrichment procedure. Copyright © 2010 John Wiley & Sons, Ltd.     

Minimizing the Dynamic Error of Measurement Transducers

A method is proposed for reducing the dynamic error of a measurement transducer of stochastic signals by introducing correcting networks into the structure of the instrument. An analytical expression is obtained for the dynamic error in the case when the transducer takes the form of a first-order inertial network while a correcting network is made in the form of a modified differentiating cell.