一种任意复杂程度二维多边形的求交算法

对于由直线段和圆弧段组成的大数据量二维多边形,作者提出一种多边形之间求交点的算法。该算法通过区域划分,把一个大规模的求交点运算分解为多个小规模的求交点运算,计算每个区域内的交点,然后对交点集进行整理,去除重复交点。该算法从实用的角度出发,避开繁琐的数学推理,便于理解,便于编程实现。算法明显地提高了求交点的效率,缩短了运算时间,并在实际应用中取得良好的效果。     

计算两凸多边形的并集多边形及其面积的计算机算法与实现

提出计算两平面凸多边形的并集(多边形)及其面积的计算机算法，并对算法实现给出详细的计算过程。程序实现中，文中将算法分为判定点是否在多边形内部、求两多边形交点、求并集多边形及其面积三部分。引入利用向量叉积符号判定三角形的方向，进而判别平面上一点是否在凸多边形内的方法，简化了计算。还进一步提出了运用“区间分割”求两相交线段交点的新颖方法。     

点在多边形内测试的新算法

判断点在多边形内是诸多领域的一个基本问题。分析了解决这一问题的一些传统算法,改进了射线交叉法。避免了射线与多边形的一条边重合、射线经过多边形顶点这两种临界情况的处理和求交点运算。算法的时间复杂度为4n次减法,3n次乘法,6n次比较（n为多边形顶点数）。程序简单易行,计算量较小。     

任意二维图形的复杂窗口裁剪算法及其应用

本文提出了一种基于交点全搜索方式的复杂二维图形裁剪算法。该算法通过引入虚边，简化复连通区域为单连通多边形，能够有效地用于多个复连通区域之间的互相裁剪。算法经实际应用证明，具有较高的效率和很好的稳定性。     

连接不相交线段成简单多边形(链)的算法

提出一个实际问题，即如何连接平面上h条线段成一简单多边形或者简单多边形链，并证明了连接平面上线段集S成一简单多边形链的一个充分条件，S中有一条线段连接凸壳CH（S）中不相邻顶点，另外还提出了连接平面上线段集S成一简单多边形或者简单多边形链的算法，其基本思想是首先逐层计算线段集S的凸壳，并将这些凸壳改变多边形；然后计算各多边形之间的交点，进而删去这些交点。最后合并若干个简单多边形为一个简单多边形，当S中线段数目n较大时，用分治思想可以设计分治算法，较好地求解了这个问题，利用计算机求解这个问题上有实际应用价值。     

格网划分的双策略跟踪多边形裁剪算法

论文提出了一种高效稳定的多边形裁剪算法,算法支持带内环的平面简单多边形,同时也支持多边形的“并”和“差”等布尔运算.首先,设计了算法所需的数据结构;其次,基于直线扫描转换Bresenham算法原理提出了边网格划分的有效算法,并应用一个简单的方法避免不同网格内边的重复求交;最后,将交点分类为普通交点和顶交点,并针对这两类交点构造了不同的跟踪策略,在跟踪过程中交替、递归地应用这两个策略来确保算法处理特殊情况时的稳定性.与其它同类算法的比较表明,新算法具有更高的效率.     

图像腐蚀和膨胀的算法研究

本在图像腐蚀和膨胀的传统算法的基础上，通过分析向量和位移运算的性质，分别对两种易于计算机实现的算法进行了研究一基于向量和位移运算的腐蚀和膨胀算法。实验结果表明该算法易于实现，并且可以极大地提高运算效率，本同时给出了三种算法的理论对比与评价，并验证了腐蚀和膨胀的一个经典的代数性质。     

利用极点顺序的多边形顶点凹凸性判别算法

提出一种根据多边形各个极点在顶点序列中的先后顺序确定多边形方向的算法.对于多边形顶点凹凸性的判别,提出通过确定某个顶点与其相邻两顶点构成三角形的方向,进而利用多边形方向与该三角形方向是否相同而确定该顶点凹凸性的方法.该算法包括了点包含的判别.试验表明,该算法不含乘法运算,使运算高效稳定.     

一种利用图形内角的多边形布尔运算新算法

现有的平面多边形布尔运算在一般情况下可以快速地获得正确结果,但如遇到奇异情况,则会产生错误。因此,采用图形内角概念分析奇异情况,并在原有交点遍历算法框架基础上给出一种全局化的奇异处理算法。与其他的多边形布尔运算算法相比,该算法对奇异的分析更为简洁有效,且具有高效性和鲁棒性。     

多边形裁剪通用算法

本文根据计算机图形学中多边形裁剪的特点，提出改进内点判断法，线段参数方程求交法和特殊交点等算法，具有通用性较强，算法简单的优点，可用于任意多边形之间的裁剪。     

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 ...