On the base stations antenna system design for mobile communications

The design of a base station antenna for mobile communications is presented. The orthogonal method (OM) is applied under constraints on nulls of the radiation pattern. In the synthesis process the mutual coupling between the elements of the antenna array could be taken into account. Beam tilting and direction of arrival are also considered. The whole design is completed by implementing a special architecture of the antenna. Finally, some examples show the applicability of our technique.     

WCDMA移动通信系统中速率匹配的研究与设计

速率匹配单元是WCDMA系统相对于其他2G到3G的移动通信系统比较独特的基带信号处理单元。论文从算法、思想、执行流程上分析了速率匹配的目的、原理与意义，并简略介绍了一种硬件设计实现的方案。     

Development and evaluation of a long‐range 300‐m leaky coaxial cable in the 2.4‐GHz band for IEEE 802.11 b/g wireless network access

In installing wireless access systems for indoor use using IEEE 802.11b/g‐complied 2.4‐GHz band wireless local area network (LAN) units, problems that arise include blind zones and interferences caused by radio waves transmitted by neighboring access point units. To solve these problems, the use of leaky coaxial cables (LCXs) is a promising method. However, commercially available flexible LCXs with small diameters for 2.4‐GHz wireless LAN were not long enough for use in tunnels, underground facilities, and so on, and the communication characteristics of LCXs long enough for these places using wireless LAN units have not been reported. We have developed a flexible 300‐m long LCX for the 2.4‐GHz band and IEEE 802.11b/g‐complied wireless LAN units with high sensitivity. We evaluated its performance with four cable configurations and confirmed that this LCX provides wireless connections over 300 m along the cable and over 20 m lateral to the cable in an open‐air environment. We also found the coverage could be extended by a method of cable‐to‐cable links. IEEJ Trans 2010 DOI: 10.1002/tee.20604     

A study on the friction and thrust force of the shaft and mobile element in the impact typed piezoelectric ultrasonic linear motor

Recently, a novel tiny piezoelectric ultrasonic linear motor driven by impact force which converts a radial mode vibration into a longitudinal one was developed for camera optical modules. This tiny piezoelectric motor consists of a shaft, mobile element and piezoelectric transducer. In this work, the frictional properties of the interface between the shaft and mobile element were investigated according to their respective materials. Five types of materials were used for the shaft, viz. stainless steel coated with DLC (Diamond like carbon) and PTFE (Polytetrafluoroethylene), uncoated stainless steel, Pyrex and Graphite. Bakelite and stainless steel (SUS) were used for the mobile elements. It was found that two combinations, namely Pyrex glass or stainless steel for the shaft and stainless steel for the mobile element, exhibited good dynamic behaviors in a tiny piezoelectric ultrasonic linear motor, which was newly developed based on operating concepts based on Newton’s law.     

南水北调工程中大型泵站泵型选择的若干问题

本文根据南水北调东线工程中大型供水泵站扬程低、年运行时间长、性能要求高等特点，对根据比转速选择水力模型、泵型参数的确定、模型性能到原型性能的换算、装置结构型式的选择等一系列问题进行了分析研究，提出了基本原则和方法。文中建议了按不同比转速进行水力模型分类的方法，根据装置参数计算所选择的泵参数的原则，根据模型装置试验成果进行原型性能参数预测的新公式，以及对装置结构型式的分类和建议采用模糊综合评判方法选择最佳的泵型装置型式。     

On the robustness of numerical algorithms for linear systems and signal processing in finite precision arithmetic

This paper proposes a model of the perturbations resulting from finite precision arithmetic implementation of numerical methods. Iterative methods for linear systems are represented as control systems, and the numerical errors caused by finite precision are represented as a multiplicative uncertainty. This representation makes it possible to use results from robust control theory to provide stability criteria, which, in turn, imply convergence, under finite precision arithmetic, of algorithms considered. Numerical examples are taken from several fields in order to illustrate the theoretical results. Copyright © 2015 John Wiley & Sons, Ltd.