摘要：In this paper, a multi-band metasurface（MS） antenna array with low radar cross section（RCS） performance is proposed and measured. Firstly, a 44 antenna array is composed of four 22 Jerusalem cross structure antenna arrays working at different frequency bands, which is aimed at enhancing the bandwidth effectively. Then, each antenna can be seen as a unit of MS in spite of adding the feeding structure. Based on phase cancellation principle, the MS is arranged into a chessboard configuration in order to realize wideband RCS reduction. Thus, excellent radiation and scattering characteristics are obtained simultaneously. Simulated and measured results indicate that this work provides a novel method to achieve bandwidth expansion as well as wideband RCS reduction of the antenna array.

摘要：室内陈设艺术设计是一门新兴艺术,是人们生活讲究品位、体现个性、审美素养提高的必然产物,在现代室内设计中已成为不容忽视的一部分;优秀人文化的室内陈设艺术设计作品,兼具人文性、交互性、原创性与实用性;把富有人文精神的要素清晰、和谐地展示在设计中,这也是室内陈设艺术设计的基本要求.

摘要：lithium-ion capacitors(liCs),consisting of a battery-like negative electrode and a capacitive porous-carbon positive electrode,deliver more than twice the energy density of electric double-layer ***,their wide application suffers from low energy density and reduced cycle life at high ***,hierarchical meso±microporous carbon nanospheres with a highly disordered structure and nitrogen/phosphorous co-doped properties were synthesized through a facile template *** hierarchical porous structure facilitates rapid ion transport,and the highly disordered structure and high heteroatom content provide abundant active sites for li+charge *** experiments demonstrated that the carbon nanosphere anode delivers large reversible capability,greatly improves rate capability and exhibits excellent cycle *** liC fabricated with the carbon nanosphere anode and an activated carbon cathode yields a high energy density of 103 W h kg^(-1),an extremely high power density of 44,630 W kg^(-1),and longterm cyclability of over 10,000 *** work presents how structural control of carbon materials at the nano/atomic scale can significantly enhance electrochemical performance,enabling new opportunities for the design of high-performance energy-storage devices.

摘要：通过建立校准坐标系,对足迹特征点进行了统一的标注和基于计算几何学的精确测量,以实现赤足迹的自动定量分析.除了常见的几何测量(如距离和角度)外,提出了一种平均曲率能量的测量方法来描述边界曲线特征.运用方差分析理论,讨论了特征参数的个体差异性和同一稳定性,为足迹识别的特征选择提供了参考依据.

摘要：传统的角接触球轴承的设计是通过反复的试凑、校核,从而最终确定设计方案的,虽能满足一般要求,但往往不是最佳的设计方案。在传统设计的基础上,为了进一步地降低角接触球轴承所受的摩擦阻力和减轻磨损,达到延长使用寿命的目的,以角接触球轴承所受摩擦力矩最小为优化目标,建立优化数学模型,并利用MATLAB软件的优化工具箱,对角接触球轴承进行优化设计,结果表明达到了优化设计的目的。

摘要：利用PRO/E建立锻件及锻模的三维实体,并对造型实体的物理特性进行计算,利用VC的计算和逻辑推理功能完成锻造工艺和模具参数的优化,实现了从产品设计到锻模设计一体化。

摘要：老年人书房桌椅的可用性设计应从老年人的身心特点着手,以用户体验为核心,以可用性为原则.文章综合调研所得数据、信息反馈和设计理论,总结出老年人书房桌椅设计的5个要素,并结合实际设计案例进行了详细分析,为开展相关的设计研究提供理论依据和实践参照.

摘要：介绍了频率选择表面的理论模型和高通滤波板的模拟结果.通过在高通滤波板中规律性地加入介质,提高了高通滤波板高通上升沿的上升速度,并在模拟中证明了其可行性.论证了使用介质填充的方法可明显优化上升沿速度,并拓展通带带宽,拓展了高通滤波板的使用范围,提高了工作性能.为先进微波成像的高斯光束空间滤波提供了理想部件.

摘要：深入研究了机车牵引电机速率特性的准确计算问题.首先分析了传统设计方法存在的问题,指出没有正确考虑电机内磁场三维分布的影响是造成速率特性计算不准的根本原因,为此,提出了直流牵引电机的二维电磁场计算修正模型.通过考虑机座的有效长度、端部漏磁以及电枢的有效长度等因素,消除了计算误差,圆满地解决了牵引电机速率特性难以准确计算的难题.最后,通过大量计算与实验结果的对比证明本文方法的正确性,并给出了工程设计曲线.

摘要：针对Z2空间中8-连通离散曲线的噪声影响,提出“序”为d的模糊线段生长算法.将曲线点上生长出的最长模糊线段作为切线的近似,并根据曲线局部粗糙度自适应地选择序,在此基础上进行离散曲率估计.实验结果表明:通过自适应选择序值,最长离散模糊线段不仅较好地反映了曲线点的局部特性,而且增加了对离散曲线噪声的适应能力,离散曲率估计的性能明显提高.