基于直线与平面投影自动识别其位置及相互关系的研究

点线面的两面投影包含其空间完整的几何信息。根据正投影的机理，建立了点线面屏幕坐标与空间关系的转换关系。基于直线与平面的两面投影、投影原理及几何定理提出直线和平面相对于投影面的位置及彼此间相互关系识别的几个算法，并在AutoCAD新一代开发环境ARX下用VC 加以实现。     

平行线束法的仿射研究

用 3 个仿射图的投射方向构成 1 个仿射坐标系,同时也构成 1 个三棱锥,在此仿射坐标系中用球面三角重新研究由两个仿射图求第 3 个仿射图的投影作图理论 ——平行线束法。进一步还给出了由两个仿射图得到正投影的条件、由两个正投影得到第 3 个正投影的条件、以及由 V,H 两投影得到指定方向上的正投影的条件,简化了研究过程,得到了更简单的公式。     

对美国机械工程图样的剖析

用正投影法绘制工程图样中，有两种画法——第一角投影法和第三角投影法。国际标准(ISO)规定这两种画法具有同等效力。我国国家标准《机械制图》规定采用第一角投影法，而有些国家则规定采用第三角投影法(如美、日等国)。本在分析研究美国第三角投影绘制的机械工程图样的基础上．     

柔性膜结构风致振动中的流固耦合效应研究

研究了采用强耦合整体方程计算柔性膜结构风致流固耦合效应的求解问题。针对柔性膜结构经历大变形的特性,在经典投影法的校正步中引入修正因子使在原始动量方法中隐性定义的压力初始边界条件得到满足,以此克服经典投影法对于大变形问题的缺陷。给出了针对强耦合整体方程的修正校正法求解过程,并推导了相关求解方程。将该方法应用于二维流固耦合问题和三维柔性膜结构风致流固耦合作用进行计算,评估了该修正投影法的性能和效率。结果表明修正投影法可以用于柔性膜结构的风致流固耦合计算,且其计算精度和效率要高于传统求解方法。修正投影法的修正值对于结果的影响不大,而计算迭代次数是影响结果的重要因素。修正投影法可以通过增加迭代次数的方法较大幅度的提高计算精度,且计算机时增加相对较少,计算稳定性不受影响。     

从投影图重建二次曲面

首次定义二次曲面截交线－位于三维空间的二次曲线的坐标概念,建立了截交线与其段影响线坐标之间的约束关系,给出了从二次曲面正投影及截交线的投影重建二次曲面和截平面的计算公式,据此建立了从轮廓线和截交线投影重建二次曲面体的方法。     

屏幕上点的斜面透视投影坐标式及计算机的绘图

推导出来的屏幕上点的斜面透视投影坐标式，完全满足计算机易于使用的参数方法的要求。用它编程，不但可以把正投影中点的坐标或曲线的参数方程转换成屏幕上能够直接显示点的透视投影的坐标或曲线的透视投影的参数方程，而且除了赋值不同外，对绘一点透视，二点透视和三点透视都具有通用性。此法与矩阵法相比，数学知识简单，易运用，特别是完全可以直接应用曲线的参数方程，更显示其优点。     

对GB/T 4458.6-2002剖视图相关问题的分析与建议

研究了GB/T4458.6-2002[1]存在的不足,指出GB/T中图样画法必须在正投影原理的层面上阐述相关问题。提出了投射方向直接表示方式与间接表示方式;投影面直接展开法与间接展开法;投影直接关系与间接关系。使投射方向表示方式,投影面展开方法和投影关系等相关问题更细化,更科学。进而可清晰、准确地阐述图样画法问题。并对GB/T4458.6-2002提出了修订建议。     

螺旋的共轭轴理论及其应用

本文提出了两螺旋公共共轭轴线偶及其解析计算公式,论证了螺旋面上螺旋辐射线投影及其几何意义。证明元柱蜗杆、蜗轮的“啮合轴”正是蜗杆齿面螺旋和蜗轮、蜗杆相对瞬时运动螺旋的公共共轭轴线偶。蜗杆、蜗轮齿面的接触线是公共共轭轴线偶之一,在蜗杆螺旋齿面上的正投影。证明滚切齿轮(包括渐开线和非渐开线、直齿和斜齿)时存在一啮合极点和极平面。滚刀和齿轮的接触点在确定的极平面上,是啮合极点在齿面上的正投影。为应用空间啮合原理精确设计、研究滚刀,提供了几何模型和新的简便而精确的计算方法。     

大视野动态体视投影探讨

互补色体视图的视野,受到立体视野、颜色视野和滤色镜的限制,图幅很小。本文提出了采用和动态观察时双眼同轨迹、同方位的动态视点,用一系列变换的投影体系进行投影的“动态投影法”。并建立了水平投影面、正交投影面、圆柱投影面等与动态投影相适应的画面,以扩大体视投影的视野和加强体视效果。为了计算和消除动态观察产生的空间象畸变,推导了以下计算公式:1.旋转视点水平投影面体视投影的线性象差、象差视角、体视角差、视差和集合角计算公式。2.旋转视点正交投影面体视投影的垂直象差、转折点象差计算公式。3.旋转视点圆柱画面体视投影的最大垂直视差点定位、最大垂直视差、作图象差和旋转象差的计算公式。根据上述计算,运用视觉生理中视敏度和离心度的函数关系,提出了消除畸变的象差分配法。探索了动态投影、动态观察中的图学、生理学问题。取得了大视野动态体视投影的三维成象效果。     

肋板结构剖视图的正确画法

从剖视图概念和正投影原理方面，对目前使用的《机械制图》教材中列举的肋板剖视图画法的错误进行了分析，提出了正确画法，并建议国标采纳。     

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.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

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.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

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 ...