基于圆矩变换的圆形印章配准方法研究

本文提出了被称为圆矩变换的印章配准方法。首先把圆形印章转化成矩形印章,得到印章的矩形图像,把印章图像从二维数据转换成一维数据,将圆形印章图像沿着一条半径展开成矩形,得到矩形图像,然后把矩形图像向x轴投影,得到投影曲线;通过预留印章与待测印章投影曲线的循环移位完成配准。针对配准后的预留印章和待测印章计算得到平均相对误差,利用平均相对误差进行印章的真伪鉴别。实验结果表明,这种方法能够简化运算量,有效地提高印章真伪鉴别效果,可以应用在实际当中。     

灵东水库平面控制网的投影变形抵偿分析

文章结合灵东水库除险加固工程,阐述了应用TrimbleGPS全球定位系统施测、TGO平差软件处理数据的情况,介绍投影变形抵偿计算在工程控制网中的重要性,以及投影变形抵偿解决方案的选择。     

灵东水库平面控制网的投影变形抵偿分析

文章结合灵东水库除险加固工程,阐述了应用TrimbleGPS全球定位系统施测、TGO平差软件处理数据的情况,介绍投影变形抵偿计算在工程控制网中的重要性,以及投影变形抵偿解决方案的选择。     

Auto CAD三维实体向二维轴测图、三视图的转换

阐述了Auto CAD三维实体向二维轴测图、三视图的转换方法,运用Auto CAD绘制的三维实体图比轴测图、三视图更直观、更容易理解。对于一些复杂的相贯图形更是如此,并且三维实体图能够进行任意位置的剖切,更容易了解其内部构造,本文将详细说明如何将三维实体转换为二维轴测图、三视图,提高做图的效率和精确度。     

第一角投影法与第三角投影法的关系探讨

院在绘制工程图样时,我国和世界上许多国家主要采用第一角投影法,其他一些国家主要采用第三角投影法.这两种投影法都是正投影法大类中多面正投影的一种画法,它们之间存在着相互区别又紧密联系的关系.本文就国际上常用的第一角投影法与第三角投影法进行了比较、分析,从而使高职学生更准确的掌握这两种投影法     

基于AutoCAD的轴测图绘制及其尺寸标注

轴测图是在二维绘图环境下绘制出来的具有立体视觉效果的图形,其绘制不需要三维图形的知识,也不完全等同于二维平面图形的绘制,文章主要讨论阐述了轴测图的绘制及其尺寸标注的方法。     

谈负后角结构在注塑机轴杆机构设计中的比较优势

文章通过对比注塑机合模轴杆机构中负后角结构和常用的正后角结构,阐述了负后角结构在注塑机轴杆机构设计中的一些优势。     

泛北部湾经济合作的效应扩散机制构建探析

扩散效应在整个区域地理空间结构的变动过程中的作用机理与运行过程就是扩散机制。文章从点轴理论出发,从"点"、"轴"和"面"三个角度来构建泛北部湾经济合作的效应扩散机制,为泛北部湾经济合作区的发展提供一些参考。     

新加坡明挖隧道监控量测及自动化数据分析平台的应用

监控量测在明挖隧道基坑开挖施工过程中起到保证施工安全和确保工程质量的重要作用.本文以新加坡樟宜机场第三跑道明挖隧道为例,对围护结构横向位移、地表沉降、地下水位、地下水压力、钢支撑应变及钢支撑轴力等监测项目进行介绍,并利用自动化数据分析平台实时预警,预防危险事故的发生.进一步说明监控量测在明挖隧道施工中的重要作用,为国内...     

傅里叶变换投影光栅法测量物体的三维形貌

文章将投影光栅法和傅立叶变换方法相结合,通过自编程序在计算机上生成正弦条纹,这些正弦条纹周期、像素可调,借助LCD投影仪将正弦条纹投射到待测物体表面,将待测物体放置前后的栅线条纹用CCD摄像机进行采集,系统参数不变,根据傅里叶变换方法进行滤波,使包含物体高度信息的相位差的图形,经过相位解包裹处理,得到被测物体的三维形貌。     

锅炉安装的工艺及技术浅析

文章将结合作者的实际工作经历,以WNS8-1.25-YQ型燃油锅炉为例,从法规文件、图纸会审、报装告知、施工工序、检测项目等方面对锅炉安装的工艺及技术要求进行分析阐述和总结交流。     

基于机械产品图样的标准化审查常见问题剖析

机械产品图样的标准化设计是保证产品图样正确、完整、统一的重要基础,对产品设计、制造和检验三者之间信息传递有重要意义。文章例举了机械产品图样在标准化审查过程中的一些常见问题,并展开分析,提出了相应对策。     

关于图学教材中某些定义和标注的商榷

针对图学教材中某些术语的概念和定义的混乱现象提出建议，对投影图视图中的标注统一问题提出看法。     

Income convergence prospects in Europe: Assessing the role of human capital dynamics

We employ income projection models based on human capital dynamics in order to assess quantitatively the role that educational improvements are expected to play as a driver of future income convergence in Europe. We concentrate on income convergence dynamics between emerging economies in Central and Eastern Europe and Western European countries during the next 50 years. Our results indicate that improvements in human capital contribute significantly to the income convergence potential of European emerging economies. Using realistic scenarios, we quantify the effect that future human capital investment paths are expected to have in terms of speeding up the income convergence process in the region. The income projection exercise shows that the returns to education in terms of income convergence in Europe could be sizeable, although it may take relatively long for the poorer economies of the region to rip the growth benefits.     

Projections Onto Efficient Frontiers: Theoretical and Computational Extensions to DEA

Data Envelopment Analysis (DEA) has been widely studied in the literature since its inception in 1978. The methodology behind the classical DEA, the oriented method, is to hold inputs (outputs) constant and to determine how much of an improvement in the output (input) dimensions is necessary in order to become efficient. This paper extends this methodology in two substantive ways. First, a method is developed that determines the least-norm projection from an inefficient DMU to the efficient frontier in both the input and output space simultaneously, and second, introduces the notion of the observable frontier and its subsequent projection. The observable frontier is the portion of the frontier that has been experienced by other DMUs (or convex combinations of such) and thus, the projection onto this portion of the frontier guarantees a recommendation that has already been demonstrated by an existing DMU or a convex combination of existing DMUs. A numerical example is used to illustrate the importance of these two methodological extensions.     

浅谈对电厂基建和技改工程竣工图管理的想法

工程档案,建设工程档案是由工程文件经鉴定、整理、归档后形成的。项目工程档案主要包括工程前期文件、工程施工文件、工程竣工验收文件、竣工图及设备厂家资料图纸等。     

浅谈控制性详细规划的编制

控制性详细规划的编制成果一般包括文件和图纸,成果内容有文本、说明书、规划图纸、分图图则。控制性详细规划编制首先是收集资料,然后对资料进行分析研究,同时提出规划需要解决的问题,接着进行方案规划设计。     

AutoCAD绘制道路工程图的要点

公路是一条带状的三维空间结构物,为了道路设计和施工的需要,要对道路进行测量,然后根据测得的数据,绘制出如下道路工程图,包括道路路线平面图、道路纵断面图及道路横断面图;笔者根据实际绘图经验,提出几点AutoCAD绘制道路工程图的要点。     

Predicting childlessness for recent cohorts of American women

Over 50% of the American women now in the midst of the childbearing years have never borne a child. These levels of childlessness for women in their 20s are the highest ones in a time series that spans most of the twentieth century. Will postponed parenthood be translated into very high levels of permanent childlessness? Or will these cohorts "catch-up" with a late fertility flurry in their 30s and 40s? The authors examine 3 projection strategies: one using women's stated fertility expectations, a second relying on the patterns of previous cohorts, and a third which posits that current rates will persist into the future. The predictive validity of these different projection strategies are tested with data for the 1980-87 period. They show that the projection based on current period rates performs well. Further, the authors argue that it better captures the first birth process than other models. They forecast levels of 20% childless for cohorts of white women born in the early 1960s. Recent trends for nonwhites are very different from those for whites: levels of 4% are forecast for nonwhite women.     

Comparison of solutions to the multi-country Real Business Cycle model

We compare the performance of perturbation, projection, and stochastic simulation algorithms for solving the multi-country RBC model described in Den Haan et al. (this issue). The main challenge of solving this model comes from its large number of continuous-valued state variables, ranging between four and 20 in the specifications we consider. The algorithms differ substantially in terms of speed and accuracy, and a clear trade-off exists between the two. Perturbation methods are very fast but invoke large approximation errors except at points close to the steady state; the projection methods considered are accurate on a large area of the state space but are very slow for specifications with many state variables; stochastic simulation methods have lower accuracy than projection methods, but their computational cost increases only moderately with the state-space dimension. Simulated series generated by different methods can differ noticeably, but only small differences are found in unconditional moments of simulated variables. On the basis of our comparison, we identify the factors that account for differences in accuracy and speed across methods, and we suggest directions for further improvement of some approaches.