Zn-Al钎料钎焊6063铝合金铺展性能及接头断裂机理分析

研究了Zn-Al钎料钎焊6063铝合金的铺展性能及接头断裂机理.钎料铺展试验表明,随着钎料中铝含量的增加,钎料铺展面积增大,铝含量增至22%(质量分数)时,钎料铺展面积达到最大,继续增加铝含量,铺展面积减小.钎焊接头力学性能试验表明,随着钎料中铝含量的增加,铝基固溶体强化相数量增加,搭接钎焊接头强度提高,铝含量增至22%(质量分数)时,钎焊接头强度达到最高,继续增加铝含量,钎缝内枝状共析组织变得粗大,与其周围组织之间容易产生应力集中,萌生裂纹,钎焊接头强度降低.综合考虑钎料的铺展性能以及钎焊接头力学性能,78Zn-22Al钎料钎焊6063铝合金性能最佳.     

数控机床全生命周期重要性测度分析

引入可靠性重要性测度进行探索分析,通过分段威布尔模型确定机床早期故障期和偶然故障期的分界点,在此基础上建立各子系统可靠性动态重要性测度模型;对早期故障期和偶然故障期子系统及整机的故障次数和故障停时进行统计分析,获得子系统失效临界重要性测度和子系统运行临界重要性测度;基于时间变化的观点对比分析三种重要性测度在早期故障期和偶然故障期确定关键子系统的差别,阐明单独采用失效临界重要性测度（故障次数）分析确定关键子系统的片面性。数控机床关键子系统的确定可为设计人员有针对性地采取纠正措施以提高数控机床可靠性和维修人员制定维修策略提供依据。     

浅析ODS与EDW关系

本文重点介绍了企业运营数据仓储(ODS)和企业数据仓库(EDW)的概念,并对ODS与EDW之间的关系,包括两者相同点与不同点进行了详尽的对比与阐述,文章还对业界公认的ODS和EDW两种不同建设方法也分别进行了说明,并给出了作者认为合理的建设方法.     

我国若干重质原油的组成及地化特征

本文采用多种分离鉴定手段,研究新疆、辽河、胜利、大港,江汉等油田的重r油,从分析结果得知:蓝质原油中的沥青质比常规原油高1~4倍,饱和烃从16.5%~64.24%,新疆克-乌地区重质油饱和烃丰富,渤海湾次之,江汉最低,根据饱和烃中的甾烷,萜烷特征,看出两种典型的重油,一是新疆风浅2井的生物降解型,一是辽河高753井的低演化型.重质油普遍含卟啉化合物其含量从痕迹到211.35ppm DPEP/ETIO从0.96~4.65.从胶质的红外光谱可将重质油分为三类,新疆克-乌地区C=O最大吸收位于1730cm^-1与1275cm^-1的醚键共轭,出现了1275, 1120,1070cm^-1强吸收,胜利大港重质油胶质C=O位于1690cm^-1,江汉青盐油田重质油胶质C=O位于1650cm^-1,重质油灰分富含金属元素,江汉盆地的22个原油灰分的分析,只在重质油中才发现Ge,其它元素也比常规油高出1~20倍,重质油也具有常规油的主要特征,即Ni含高最,钒含量低,V/Ni比值比国外海相原油低几十到几百倍.     

构造嵌入式Linux的文件系统

文件系统是Linux系统最基本的资源。本文介绍了一种嵌入式Linux文件系统的构造过程，较为详细地讲解了如何选择和配置所需的系统文件，以及如何设置文件系统的用户和属组来使系统达到一定的安全性能。该文件系统已成功应用于一款手持电脑产品中。     

五元素分析仪测量值的不确定度评定

分析和讨论了五元素分析仪测量值的不确定度的来源,并对由测试重复性和标准物质定值等引入的各不确定度分量进行了量化与合成,计算出当k=2时,各元素的扩展不确定度分别为U_(Cu)=0.0052mg/L,U_(Zn)=0.0054mg/L,U_(Ca)=0.042mg/L,U_(Mg)=0.022mg/L,U_(Fe)=0.25mg/L。     

网站建设中应注意的安全问题

目前,全国各行各业建立的网站已经越来越多,网站建设安全问题引起了人们广泛关注.本文先对网站建设应注意的安全问题及原因进行了分析,继而对应采用的安全技术进行了探析,提出了自己的思考.要从硬件软件多方面协调配置,提高其抗恶意攻击和病毒传播的能力.要把网络安全作为网站发展的一个重要步骤.     

NMR image segmentation based on Unsupervised Extreme Learning Machine

Unsupervised Extreme Learning Machine (US-ELM) is a machine learning method widely used. With good performance in anti-noise and data representation, as well as fast clustering speed, US-ELM is suitable for processing noise containing nuclear magnetic resonance (NMR) image. Therefore, in this paper, a brain NMR image segmentation approach based on US-ELM is proposed. Firstly, a median filter is adopted to reduce the influence of noise; Secondly, US-ELM maps the original data into the embedded space, which makes it increasingly effective to represent the characteristic of pixel points, and then uses the k-means method to perform the image segmentation, named NS-UE; After that, spatial fuzzy C-means (spFCM) provides a better solution for handling NMR image with noise caused by the intensity inhomogeneity than k-means does. As a result, an image segmentation approach based on US-ELM and spFCM (NS-UF) is proposed, so as to improve the effect of clustering in embedded space. Finally, extensive experiments on real data demonstrated the efficiency and effectiveness of our proposed approaches with various experimental settings.     

Automated Road Sign Inventory System Based on Stereo Vision and Tracking

Abstract: Detection, recognition, and positioning of road signs are critical components of a roadway asset management system. In this research, a stereo vision‐based system is developed to conduct automated road sign inventory. The system in real time integrates and synchronizes the data streams from multiple sensors of high‐resolution cameras, Differential Global Positioning System receivers, Distance Measurement Instrument, and Inertial Measurement Unit. Algorithms are developed based on data sets from the multiple positioning sensors to determine the positions of the moving vehicle and the orientation of the cameras. The key findings from the research include feature extraction and analysis that are applied for automated sign detection and recognition in the Right‐of‐Way (ROW) images, implementing a tracking algorithm of the candidate sign region among the image frames so the same signs are not counted more than once in an image sequence, and implementing stereo vision technique to compute the world coordinates of the road sign from the stereo‐paired ROW images. Particular techniques are employed to conduct all data acquisition and analysis in real time onboard the vehicle. This system is an advanced alternative to traditional inventory methods in terms of safety and efficiency.     

基于网络的远程监控系统研究

本文分析了基于网络的远程监控系统的体系结构，对系统开发中所涉及的关键技术进行了讨论，给出了远程通信的两种实现方法。