一种基于交点质心求解的RSSI定位算法及其优化

为了提高RSSI算法的定位精度,提出了一种新的基于交点质心求解的RSSI算法.此方法用矩阵求解多组二元二次方程组,得出的结果为这些方程组解的平均值,定位坐标由这些平均值确定.相比于传统最小二乘法,交点质心法的定位精度明显提高,并给出了两种优化方案,最后提出了一种实现三维定位的方法.     

碳纤维热氧化行为及其机理

对聚丙烯腈(PAN)基碳纤维进行热氧化处理,借助扫描电子显微镜、X射线光电子能谱,拉曼光谱等手段表征了PAN基碳纤维的热氧化行为,研究了其热氧化机理。结果表明:热氧化使PAN基碳纤维表面氧元素含量大幅升高,碳含量下降,氧以C—OH或C—O—C基团的形式吸附到表面、在550℃左右以C=O基团大量分解的形式腐蚀纤维,破坏纤维形貌;同时热氧化腐蚀纤维中的非石墨碳,使得有序的石墨结构向非石墨无序结构转变,破坏碳纤维的晶体结构。     

PP/PA6/APP/OMMT复合材料的湿热老化性能研究

采用熔融挤出插层制备聚丙烯(PP)/尼龙6(PA6)/聚磷酸铵(APP)/有机蒙脱土(OMMT)阻燃复合材料,研究温度80℃、湿度93.1%的湿热老化条件对复合材料性能的影响.结果表明,随着湿热老化时间的延长,复合材料的表面形貌变得很差,产生大量的粗糙白斑.当OMMT含量较低时,复合材料的拉伸强度随湿热老化时间的延长先上升后下降.而当OMMT含量较高时,复合材料的拉伸强度随着湿热老化时间的延长而下降.弯曲强度的变化规律与拉伸强度相似.缺口冲击强度则随着老化时间的延长而提高.引起复合材料破坏的主要原因并非是湿热老化反应导致的分子链断裂,而是复合材料内积聚的水泡和水分子渗入到各相界面引起界面粘结强度下降导致的结果.     

高等学校文科数学教学改革与实践

本文结合南京工业大学十多年来文科数学课程的教学实践,围绕大学文科专业开设数学课程的必要性和重要性以及文科数学的课程体系、教学内容、教学方法、教学手段等方面,作了初步的探讨和研究。     

一种基于滤波特征和不变矩的混合指纹识别算法

滤波特征匹配和不变矩匹配是常用的指纹识别算法,是将两种识别算法以一定的权值进行结合而提出的一种混合识别算法.通过采用来自不同手指采集的多幅指纹图像作为样本集并两两匹配,得到相应的滤波特征和不变矩匹配分数样本.而算法中权值的确定可以转换成一个匹配分数样本的分类器设计问题,用这些样本对权值进行分类学习估计.以100对指纹图像对混合识别算法进行测试,结果证明该算法具有较好的识别效果.     

Relationship Between Embedding Depth and Residual Stress in the cBN Grain of Monolayer Brazed Abrasive Tools

The relationship between the embedding depth and the residual stress in the brazed cBN grains is analyzed experimentally in order to optimize the embedding depth of grains in the monolayer brazed abrasive tools. It is found that the residual stress is stable without remarkable gradient in the core zones of the brazed grains. However, the stress distribution gradient is rather great in the regions such as both ends of the central axis, the margin region of the central plane in the cBN grains, and the margin region of the section plane between the grains and the filler top. The maximum tensile stress in the margin zone of the brazed cBN grains has the most important influence on the mechanical property of the grains. The embedding depth is accordingly optimized at 30-40% of the total height of cBN grain.     

J4不锈钢热轧板冷轧横裂原因分析

分析发现了J4不锈钢热轧板冷轧横裂形成的主要原因是:钢中有大量显微气泡破坏基体的连续性,降低材料的塑性,导致裂纹形成。加大脱氧、脱气力度,可减少显微气泡,预防裂纹形成。     

Desorption kinetics of trichloroethylene and perchloroethylene from aged dense nonaqueous phase liquid-contaminated soil

Batch experiments were conducted to investigate the desorption kinetics of a contaminated soil collected from a field site at Hill Air Force Base (AFB), Utah. The site has been contaminated with many dense nonaqueous phase liquids (DNAPLs), primarily trichloroethylene (TCE) and perchloroethylene (PCE), for more than 60 years. Similar desorptive behaviour of both TCE and PCE was observed: a stage of fast release of the contaminant at the start followed by a very slow stage. Moreover, it is suggested that not all the contaminant in the solid phase may be released to the aqueous phase, apparently due to the age factor. Local variations were observed in the effective diffusivity and other sorption-related parameters across the site due to aquifer heterogeneity. Experimental results were then simulated using a numerical code based on the intraparticle diffusion model. Good agreement was found between both results.     

高层建筑外整饰工程排栅脚手架施工方案及其安全管理

通过广州市区某临近内环路的高层建筑外整饰工程实例,介绍脚手架搭设的施工技术方案及其安全技术管理措施,为同类施工提供参考。     

楼宇自动化系统(BAS)在现代建筑工程中的进化与应用

概述了构成智能建筑的基本框架,根据涉外工程实施的经验,介绍了其中楼宇自动系统的分类、特性,基本功能及系统结构,基于目前技术和经济水平下的成本限制,大多数检测设备和执行装置不具备网络通信功能,而是以模拟信号与现场DDC系统直接连接的,是数字技术与模拟技术共用的混合结构。并展望了楼宇自动化系统的发展趋势。