参数相同电子器件组成的串联、并联电路谐振频率和品质因数的分析

用参数相同电子元器件构成的串联和并联电路,通过分析得知,这两种电路的谐振频率近似相等,品质因数相等。     

大振幅平面声波在多层介质中的传播

本文用逐级近似法就一维情况下分析了大振幅平面声波在多层介质的界面上发生反射和透射的传播特性。在二级近似下计算了精确到二阶小量的二至三个界面各层的反射波和透射波的二次谐波，并推广至几个界面，得到一些规律性的结果。从拉格朗日坐标下的一级近似和二级近似的波动方程式出发，假定声波在多层介质中传播在各个界面仍是连续的，即各层界面的边界条件由界面两侧的压力平衡和质点速度相等来决定，由此求得各层界面在二级近似下的二次谐波的反射波和透射波。计算结果表明，二级近似下的反射波和透射波均由两部分组成，一部分是由一级反…     

论炸药和岩石的能量匹配

论述了炸药和岩石的阻抗匹配、全过程匹配和能量匹配的基本原理。传统的阻抗匹配以阻抗为基础，要求炸药阻抗等于或近似等于岩石的波阻抗。全过程匹配要求弹性摸量大、泊松比小的坚硬、致密岩石选用高威力炸药；松软、塑性大、强度低的岩石选用爆速低、爆热高的炸药。从能量匹配原理可知，破碎岩石所做功的能量应与炸药爆破产生的能量相等或基本相等，因此可通过增减装药量来调整作药爆破能量，以适应破碎岩石的需要。     

服装样片二、三维转换算法

服装样片二、三维之间进行转换的算法，使得服装样片二、三维转换得到统一实现。服装样片二维到三维和三维到二维的转换，满足转换前后，二维样片和三维样片的面积应近似相等，边界线相互对应且长度保持相等，关键点的位置应相互对应的条件。此过程应用Delaunay三角化技术、散乱数据插值技术，目的就是求出二、三维服装样片之间相互对应的中间点。最后利用可视化技术，给出了转换结果的直观效果，验证了该方法的可实施性。     

论炸药和岩石的能量匹配

论述了炸药和岩石的阻抗匹配、全过程匹配和能量匹配的基本原理。传统的阻抗匹配以阻抗为基础，要求炸药阻抗等于或近似等于岩石的波阻抗。全过程匹配要求弹性摸量大、泊松比小的坚硬、致密岩石选用高威力炸药；松软、塑性大、强度低的岩石选用爆速低、爆热高的炸药。从能量匹配原理可知，破碎岩石所做功的能量应与炸药爆破产生的能量相等或基本相等，因此可通过增减装药量来调整作药爆破能量，以适应破碎岩石的需要。     

基础频响有理近似的稳定性和识别:离散时间的递归算法

基础频率响应的离散时间有理近似是构建基础振动分析的时域递归算法的起点,离散时间有理近似的稳定性和精度决定时域递归算法的稳定性和精度。该文采用双线性变换法从基础频响的连续时间有理近似获得离散时间有理近似,避免离散和连续时间频率相等情况下由于离散时间有理近似的周期性而产生的高频尾部丢失和混叠现象,保证离散和连续时间有理近似的稳定性和精度一致。基于部分分式展开,获得的离散时间有理近似分别实现为直接型和并联型时域递归公式。通过分析几个典型基础振动问题并与Wu-Lee集中参数模型结果进行对比验证了双线性变换的有效性。     

金属橡胶用螺旋卷拉伸质量控制技术研究

建立了螺距相于簧径拉伸后的螺旋卷长度和扭转圈数计算的数学模型。分析发现,当螺距与簧径相等时,螺旋卷长度与丝线长度的比值近似一个与簧径和丝径无关的常量,约等于0．3033。依据上述理论,创新性地提出了螺距与簧径相等的螺旋卷长度比值法拉伸工艺,解决了螺旋卷拉伸过程中同时存在弹、塑性变形而难于实现螺距与簧径相等及扭转控制的工艺难题。     

离心泵调速节能分析

阐述了离心泵及调速节能原理，给出了在流量变化工况下两种调节方式的轴功率比较，并进行节能效果分析。变速调节方便灵活，经济合理，将离心泵的调节方式带入了现代化的模式。应用表明，调速后泵的效率近似相等，可保证泵在高效区工作，即泵的效率高，节能效果明显。通过泵变速调节，可减小流量，有利于降低离心泵发生汽蚀的可能性。     

油墨渗透下荧光半色调印刷品的预测模型

旨在普通油墨渗透条件下,建立能预测不同浓度的均匀荧光油墨半色调印刷品的呈色规律的理论模型;在假定油墨是非散射介质以及油墨的折射率与纸张的折射率近似相等的近似下,利用光在油墨与纸张中散射迁移路径长短不同的分程理论,建立了油墨渗透下荧光油墨半色调图像的分程Clapper-Yule光谱反射率模型.     

铝塑复合板和单铝板的LCA研究

采用国内杨建新生命周期评价（LCA）和国外荷兰的EI99两种方法比较了新兴装饰材料铝塑板和单铝板的相对环境负荷。采用EI99方法得出的铝塑板与单铝板的环境负荷的相对值与采用国内杨建新LCA方法计算得出的结果近似相等，由此可知，如果为了检验某种评价方法的准确性时，对类似产品/材料进行环境影响评估对比，采用两套以上的方法加以相对误差比较的做法是可行的。     

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.     

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