由二维视图复原三维立体的新方法

根据工程图学和三维CAD课程的教学实践,研究、总结出一种将三维CAD中立体的构型原理、方法和成型过程用于二维视图阅读的新方法。该方法将传统的二维读图方法与现代三维CAD有关内容融合到一起。按此方法读图,不仅可以使学生根据二维视图快速复原立体空间形状,而且可以了解立体的成型方法和最佳构型过程,为三维CAD构型设计奠定基础。     

组合体读图技巧探讨

读图是一种从二维平面图形,通过思维、构思、在想像中还原成三维空间物体的过程。本文通过组合体的形成结构特点,举例说明读图的具体步骤和借助画图切割过程读图的方法技巧。     

三维建模引入制图课程的改革研究

指出将三维建模引入工程图学课程是学科发展的必然趋势,介绍了国内图学教育工作者的不同论点和实践模式。分析了制约三维设计方法在短期内不能完全取代二维绘图的原因,提出了三维建模与传统图学内容相结合的教学改革方向。阐明了现阶段三维建模内容在图学课程中的作用,阐述了在图学课程的不同阶段引入三维建模的具体方式以及教学软件的选择,由此建立了新的图学课程教学体系和内容。     

UG在车用发动机的虚拟设计方面的应用

随着计算机辅助技术的发展,计算机辅助设计技术已从二维绘图发展到当今的三维建模设计。传统的以AutoCad为代表的二维设计越来越不能满足工业生产、设计的需求。     

机械制图教学内容的程序化创新设计研究

研究并提出了制图课教学中正确的思维方式,通过与当前思维方式的比较找出了教学中存在的问题,即一味强调形象思维,过分忽视逻辑思维。以组合体读图为例,对该教学内容进行了程序化创新设计和强化逻辑思维,并进行了教学实践。实践表明新方法改变了过去课堂教学中听得懂但不会用的状况,深受学生欢迎。     

运用三维绘图软件SolidWorks改革工程图学教学的实践

指出了二维绘图软件AutoCAD已经不能满足目前企业新产品设计的需要以及现有的多媒体CAI课件仍然不能充分发挥教师的主导作用，不能满足交互性和实时性的教学需求。论述了工程图学引入三维CAD软件的必要性和重要性。运用三维机械软件SolidWorks，提出了三维画法几何，并从三维入手改革了工程图学的教学，连续3年在15个班的学生中进行了试点，取得了良好的教学效果。总结了改革过程中的一些做法和经验。     

现代工程图学教学的几点思考

针对现代工程图学教学的目的,总结了教学实践中的做法与体会,即：重视投影入门,夯实理论基础：运用多种手段,培养空间想象能力：重视组合体转运教学,强化读图能力：将专业图与CAD教学相融合,提高教学效率和学生的实践应用能力。     

工程图学装配图读图的CAI课堂教学

装配体装拆过程的三维动态模拟，装配体装拆过程的二维视图动态模拟，由装配图拆画零件图的二维过程演示，这三者构成了工程图学中有关装配图读图部分完整的课堂教学模式。笔者结合工程图学独特的教学特点，论述了上述课堂教学模式中3个组成部分之间的内在联系和不可分割性。并以作者所在课题组的CAI课件研制成果为例，介绍了该课堂教学模式在课件中装配图读图部分的总体设计、实现方法与过程。     

MapGis煤矿地质模型应用研究

本文主要研究了煤矿地质模型的建立以及应用，相比二维和三维之间的建模效果，三维地质模型直观，以及有利用后面的分析应用，二维相对来说，就显得没有那么好的效果，但是在分析的时候，二维地质模型就比较灵活了，对于地表面点的查询、地形的分析、剖面分析的剖面线高程的显示就有三维体现不了的效果，或者说三维有的就不能实现。文章将展开对于二维、三维地质模型的建立与应用优势的论述。     

多学时制图课程融入三维CAD的教学探讨

针对机械类多学时传统制图教学中如何融入三维CAD教学的问题,分析了其融入的形式和特点,归纳了工程图表达中与投影相悖的表示法,提出分两步走的方法:首先以传统制图内容与三维CAD相互支撑的融合式教学,然后以三维CAD为主线的独立式教学相结合。在教学上,可通过Inventor三维建模的实践,提高学生的工程图表达能力、创新思维能力和构型能力,以适应现代设计和制造的要求。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.     

新闻(英文)

正China and Greece Sign the Standardization Cooperation Agreement Witnessed by Chinese Premier Li Keqiang and Greek Prime Minister Antonis Samaras,AQSIQ Minister Zhi Shuping and ELOT Chairman and Executive Director Angelos Tolkas signed the SAC-ELOT Standardization Cooperation Agreement.The Agreement is one of the critical cooperation documents signed during Li Keqiang’s visit in Greece,encouraging China and Greece to