用三维点云计算活塞腔的体积

提出一种从三维点云计算活塞腔体积的方法。利用高精度的光学或接触式测头对活塞腔进行密集测量，得到活塞腔的三维密集点云数据。通过对三维点云的处理，分割出参考平面，重构其曲面几何模型，用数值积分的方法计算活塞腔的体积。同时，分析了这种方法的两种误差－离散误差和测量误差。     

用三维点云计算活塞腔的体积

提出一种从三维点云计算活塞腔体积的方法。利用高精度的光学或接触式测头对活塞腔进行密集测量 ,得到活塞腔的三维密集点云数据。通过对三维点云的处理 ,分割出参考平面 ,重构其曲面几何模型 ,用数值积分的方法计算活塞腔的体积。同时 ,分析了这种方法的两种误差———离散误差和测量误差     

三维激光扫描技术在犯罪现场重建中的应用

目的:研究利用三维激光扫描技术进行现场重建的技术方法。方法:首先,利用三维激光扫描仪对现场进行扫描,获取现场的点云数据;然后,依据点云数据进行现场建模和动画模拟。结果:精确地重建了犯罪现场的场景并获得具有交互性、沉浸感的动画模拟效果。结论:利用三维激光扫描技术可以精确、方便地进行现场重建。     

一种简便的地面激光扫描仪精度检测方法

一、引言 地面激光扫描仪（Terrestrial Laser Scanner,TLS）是一种不同于传统单点测量方式的新型光电测量仪器,它采用非接触式高速激光测量方式,可在复杂的现场和空间对被测物体进行快速高密度扫描测量,以便快速、高效、精确、全面地获取被测目标表面的空间点位及亮度信息——点云数据。点云数据经过计算机处理后,     

列车车轮三维结构光检测中的点云处理研究

列车轮对作为转向架的关键零部件,其检测手段仍以人工检测为主,现有的自动检测方案,大多针对车轮某一断面的参数尺寸进行测量,难以真实反映车轮轮缘踏面的损伤情况。为此,该文提出一种列车车轮三维结构光检测中的点云处理方案。首先,利用三维结构光测量仪器采集列车车轮的三维点云数据;其次,根据列车车轮三维点云的特点,确定包括离群点去除、点云配准、点云平滑处理以及孔洞修补在内的点云处理方案,并对各处理步骤的最优参数进行分析;最后,利用贪婪投影三角化算法,进行列车车轮三维点云数据的曲面重建,使用拉普拉斯平滑算法对重建后的曲面进行平滑处理。结果表明,该文所提出的列车车轮点云处理方案能够实现对三维点云数据的处理,最终得到的列车车轮的三维曲面模型与基准模型的标准偏差为1.768 mm,实现对于列车车轮的三维检测。     

汽车钣金件虚拟装配实物数字化研究

本论文旨在通过非接触式测量获得实物数据,并对原始点云数据进行处理,利用处理过的点云数据进行模型重构,利用逆向工程建立实物模型,以达到虚拟匹配计算的前期准备需求。     

基于逆向工程的零件反求设计与制造

反求设计与制造是逆向工程的重要组成部分,以PCP系列便携式光学三维扫描系统为基础,介绍逆向工程技术在零件反求设计与制造中的应用。利用三维数字化激光测量仪准确、快速地测量出工件的轮廓坐标,通过Winmoire扫描软件得到零件模型各个面的轮廓点云数据,再通过Cloudform拼接软件将各个面的轮廓点云数据合成为三维点云数据模型,最后通过Geomagic studio11建模软件进行曲面重构,并对重构的曲面进行分析和优化,最终生成STL数据,据此进行快速成形加工得到零件。     

汽车发动机缸盖燃烧室容积数字化检测

本文针对现有缸盖燃烧室容积滴定法测量中测量精度低、测量速度慢等不足,提出一种使用线激光三维测量系统扫描缸盖燃烧室的发动机缸盖燃烧室容积的数字化测量方法,实现了对缸盖燃烧室容积的快速、精确计量,并应用于工程实际。论文介绍了测量原理和检测方法;详细阐述了获取缸盖燃烧室点云后通过一系列滤波及容积计算程序,获得缸盖燃烧室容积的过程,即点云的滤波处理、孔洞修补、曲面重建、燃烧室有效点云提取及容积计算等;最后,基于样机平台,对上述方法进行了实验验证。     

基于线激光的鱿鱼扫描系统与分割算法研究

目的:为实现低成本、等重量、自动化分割鱿鱼。方法:基于线激光扫描获取的点云,提出了一种结合线激光点云数据分析、表面重建及鱿鱼体积估测等方法的鱿鱼体积分割算法,使用三维激光扫描仪结合LabView获取鱿鱼表面的三维点云数据,为了还原鱿鱼表面形貌,使用阈值分割法去除点云数据里的噪点,根据分割算法确定分割点位置,对鱿鱼产品进行等侧边对角线等重量分割。结果:对角线长度最大误差为0.86%,重量最大误差为0.94%。结论:基于线激光的鱿鱼扫描系统实现了鱿鱼精确分割,符合企业的生产需求,为鱿鱼生产自动化提供了技术支持。     

气膜孔视觉测量系统的设计与搭建

为了重建高压涡轮导向叶片气膜孔的三维形貌特征,基于机器视觉原理,设计并搭建了非接触式的气膜孔四轴视觉测量系统。该系统主要由三坐标测量机框架、高精度回转台、叶片专用夹具和图像采集装置构成,将视觉测量技术和三坐标测量技术结合起来以应对气膜孔的检测问题。为了获取气膜孔的三维形貌数据,提出了应用景深合成技术进行孔壁三维形貌重建的方法,并通过实验进行了重建方法的验证。在实验过程中,应用该测量系统对某个高压涡轮导向叶片上的气膜孔特征进行了测量实验,获取了孔深范围内的对焦图像序列,而后对其进行了景深合成与深度信息转化,最终实现了该气膜孔的孔壁形貌的三维重建与显示,并实现了向三维点云数据的转化,充分说明了所搭建的气膜孔视觉测量系统的有效性。     

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.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

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.