A 3-D Enlarged Cell Technique (ECT) for the Conformal FDTD Method

In this paper, we present an enlarged cell technique (ECT) to avoid the time step reduction encountered in the conformal finite-difference time-domain (CFDTD) method due to small irregular cells truncated by metallic boundaries. We focus our efforts on the discussion of the accuracy and stability of the ECT and its comparison with other conformal methods, especially the one called the uniformly stable conformal (USC) method. We also provide a simplified ECT, which is much easier to implement. In the ECT, a stability criterion is first constructed to identify instable irregular cells, i.e., those having so small an area to cause instability. Those instable cells are then enlarged into their adjacent cells to obtain a large, stable area. Careful treatment is performed on the communication between the intruding and intruded cells in terms of electromotive force by keeping the total electromotive force conservative. This technique is verified by several 3-D numerical experiments. Results show that the ECT is second-order accurate and numerically stable at the regular Courant time step limit.     

高精度快速可控光纤真延迟线实验研究

在相控阵雷达中使用光纤实时延迟技术,可实现大角度瞬时宽带扫描.利用半导体光放大器和法拉第旋转镜实现了快速切换的延迟线,此技术具有切换速度快,延迟精度高,输出功率恒定,偏振不相关等优点.实验结果表明,此结构能够实现1 ps的延时精度,误差不超过0.1 ps.     

Nutrient removal performance of an anaerobic–anoxic–aerobic process as a function of influent C/P ratio

The laboratory scale anaerobic–anoxic–aerobic (A²O) process fed with synthetic brewage wastewater was designed to investigate the effects of changing feed C/P ratio on the performance of biological nutrient removal (BNR) processes. In the experiment, the influent chemical oxygen demand (COD) concentration was kept at approximately 300 mg L^?1 while the total phosphorus concentration was varied to obtain the desired C/P ratio. Results showed that when the C/P ratio was lower than 32, phosphorus removal efficiency increased as C/P ratio increased linearly, while when the C/P ratio was higher than 32, the P removal efficiency was maintained at 90–98%, and effluent P concentration was lower than 0.5 mg L^?1. However, regardless of the C/P ratio, excellent COD removal (90% or higher) and good total nitrogen removal (75–84%) were maintained throughout the experiments. It was also found that very good linear correlation was obtained between COD uptake per unit P released in the anaerobic zone and C/P ratio. In addition, the P content in the wasted activated sludge increased with the decrease in the C/P ratio. Based on the results, it was recommended that the wastewater C/P ratio and its effects be incorporated into BNR design and operational procedures, appropriate C/P ratios were used to achieve the effluent treatment goals. Copyright © 2005 Society of Chemical Industry     

变频液压泵控压力流量控制开环实验及其结果分析

该文首先分析了变频液压泵控调速调压实验控制系统的理论基础,从理论上分析加阻尼后系统开环时恒流的可行性;并付诸实验研究;然后结合实验曲线进行分析,阐明其控制性能优劣.     

沼气脱硫技术研究

本文综述了近年研究人员在开发沼气脱硫工艺方面所做的工作,包括现代与传统的脱硫技术工艺.探讨了物理、化学和生物脱硫技术对沼气脱硫工艺的影响因素.     

使用IP/ NetBEUI组合协议建造跨VLAN的VoD网站的方法

介绍一种使用IP和NetBUI组合协议建造Intranet内部VoD(视频点播)网站的简便技术。并已成功地运用这一技术建成了莆田学院的VoD网站。     

企业实施精益生产的探讨

通过描述造成企业经济效益差的原因之一——浪费，提出了如何实施精益生产，消除企业浪费，以提高企业经济效益．