采用PLC技术完善生产过程监控

介绍了为监控生产过程 ,经过硬件和软件等多方面的改进 ,实现了生产全过程的控制和管理。     

Role of Long-Range Protein Dynamics in Different Thymidylate Synthase Catalyzed Reactions

Recent studies of Escherichia coli thymidylate synthase (ecTSase) showed that a highly conserved residue, Y209, that is located 8 Å away from the reaction site, plays a key role in the protein’s dynamics. Those crystallographic studies indicated that Y209W mutant is a structurally identical but dynamically altered relative to the wild type (WT) enzyme, and that its turnover catalytic rate governed by a slow hydride-transfer has been affected. The most challenging test of an examination of a fast chemical conversion that precedes the rate-limiting step has been achieved here. The physical nature of both fast and slow C-H bond activations have been compared between the WT and mutant by means of observed and intrinsic kinetic isotope effects (KIEs) and their temperature dependence. The findings indicate that the proton abstraction step has not been altered as much as the hydride transfer step. Additionally, the comparison indicated that other kinetic steps in the TSase catalyzed reaction were substantially affected, including the order of the substrate binding. Enigmatically, although Y209 is H-bonded to 3''-OH of 2''-deoxyuridine-5''-mono­phosphate (dUMP), its altered dynamics is more pronounced on the binding of the remote cofactor, (6R)-N⁵,N¹⁰-methylene-5,6,7,8-tetrahydrofolate (CH₂H₄folate), revealing the importance of long-range dynamics of the enzymatic complex and its catalytic function.     

基于模糊PCNN的小波域超声医学图像去噪方法

在分析了斑点噪声和PCNN的特点的基础上,将PCNN引入到小波域中,并结合小波软阈值去噪思想,提出了基于PCNN的超声医学图像软阈值去噪方法(ST-PCNN),该方法的优点是实现了在小波域中利用PCNN来识别高频信号的小波系数,并采用相应的方法处理小波系数,改善了PCNN难以确定斑点噪声的位置和采用固定阈值造成高频信号损失的缺点,更好的保留了低于固定阈值的高频信号的小波系数;在此基础上,将模糊算法引入到PCNN模型中,进一步提出了基于模糊PCNN的小波域超声医学图像去噪方法(F-PCNN-WD),该方法利用模糊算法来去除PCNN点火过程中大于点火阈值的斑点噪声的小波系数,以更好的去除斑点噪声。实验结果表明,ST-PCNN和F-PCNN-WD方法不仅能够有效地去除噪声,而且能够很好的保留图像的边缘和细节信息。     

结合小波变换与相位相关的图像匹配方法

图像匹配技术是图像测量系统中的关键技术,是目标定位中最基本的方法。相位相关作为一种图像匹配技术对噪声有较高的容忍程度,检测结果与照度无关,受几何失真影响小。但该方法对旋转变化非常敏感。为解决此问题,本文提出结合小波变换和相位相关的匹配算法,该算法首先对图像进行小波分解,并对结果中的近似信号进行空域旋转校正;然后利用相位相关方法进行图像匹配,从而达到快速精确的定位。该方法在掌纹图像匹配定位中的应用证明了它的有效性。     

人世后的陶瓷业

我国加入世贸组织,古老的陶瓷业也是机遇与挑战并存,如何迎接新的市场经济的挑战,进行国际市场营销便成了我国陶瓷企业面临的一个重要问题.本文分析了国际陶瓷市场的新特点,研究了我国陶瓷企业的国际市场营销策略.     

防腐涂料和涂装技术(IV)

防腐涂料及涂装技术讲座系列介绍防腐涂料的品种及其应用、防腐涂料的主要组成部分以及工件表面处理和施涂工艺等。本讲主要介绍涂料组成中的溶剂和助剂 ,包括分散剂、润滑剂、流变助剂等     

Optimisation of solar-hydrogen power system for household applications

A numerical method was developed for optimising solar–hydrogen energy system to supply renewable energy for typical household connected with the grid. The considered case study involved household located in Diyala Governorate, Iraq. The solar–hydrogen energy system was designed to meet the desired electrical load and increase the renewable energy fraction using optimum fuel cell capacity. The simulation process was conducted by MATLAB based on the experimental data for electrical load, solar radiation and ambient temperature at a 1-min time-step resolution. Results demonstrated that the optimum fuel cell capacity was approximately 2.25 kW at 1.8 kW photovoltaic power system based on the average of the daily energy consumption of 6.8 kWh. The yearly renewable energy fraction increased from 31.82% to 95.82% due to the integration of the photovoltaic system with a 2.25 kW fuel cell used as a robust energy storage unit. In addition, the energy supply, which is the economic aspect for the optimum system, levelised electricity cost by approximately $0.195/kWh. The obtained results showed that the proposed numerical analysis methodology offers a distinctive property that can be used effectively to optimise hybrid renewable energy systems.     

基于STFT和WT的SAR干扰抑制算法

窄带干扰(NBI)和宽带干扰(WBI)作为合成孔径雷达（SAR）中最为常见的两种干扰形式,它们的存在将会大幅度地降低SAR图像的质量.本文在对NBI和WBI的时频聚集性分析的基础上,提出一种联合短时傅里叶变换和小波变换的NBI和WBI抑制方法.该方法首先把SAR回波数据变换到短时傅里叶谱域再把短时傅里叶谱域数据变换到小...     

一种利用子波变换多尺度分辨特性的信号消噪技术

本文基于传统信号处理方法对非平稳信号的局限性，利用子波变换下奇异信号和随机噪声在多尺度空间中不同的模极大值传播特性设计了一种实用的子波消噪方法，对不同信号的仿真结果表明该方法既能提取一定的信噪比改善增益，同时又能保持对突变信息的良好分辨率，适合于一类非平稳信号进行时变处理．     

基于小波变换和DCT的字符图像特征抽取新方法

从特征矢量的不变性和抗噪性角度,提出了一种基于小波变换(WT)和离散余弦变换(DCT)的字符特征抽取新方法。利用圆周投影算法,把二维的字符图像转换为一维投影。基于WT和DCT的非线性变换,克服了因变形和噪声引起的一维投影的非线性变形失真。通过对识别不同大小、方向及噪声的字符仿真实验和不同特征抽取方法的对比实验,以及对工业标牌字符的识别,表明该特征抽取方法具有尺度和旋转不变性,有较好的抗噪声能力和很好的分类性能。