风机的使用方法及经济效益

风机内部损失，提高风机效率。风机在把原动机的机械能转换成流体的机械能的过程中，要产生各种能量损失，这些损失按其性质可分为机械损失、容积损失和流动损失三部分。由于风机内部流体运动的复杂性，上述各种损失至今仍不能用理论方法计算出精确的结果，主要依靠试验方法测定，再由此总结出半经验半理论的计算公式。要提高风机本身的效率，就要减少上述各种损失。     

存在气流的消声扁管道声学特性的实验研究

本利用Ｍ序列相关技术有效地抑制背影噪声的特点，对不同气流下的扁消声管道的声学特性做了实验研究，对插入损失和传递损失随气流马赫数的变化，进行了Ｍ序列法测量，并与理论值及传统方法的测量值做了比较，实验表明，存在气流时，消声特性的Ｍ序列相关技术测量结果，比传统方法具有更高的可信度。     

西林电桥(QS1)测试中常忽视的问题

通过西林电桥（QS1型）对电力设备测试结果可靠性及其试验方法的评价，介绍了在其试验环节存在容易忽视的常见问题，分析了这些问题产生的根本原因，对其试验结果产生的影响进行了具体的说明。根据对电力设备介质损失角正切值tgδ试验的实际，介绍了使用西林电桥（QS1）测量各种电力设备介质损失角正切值tgδ的方法、注意事项及规范要求，并提出如何将各项试验结果全面综合分析判断，对被试设备的绝缘状况和缺陷性质作出科学的结论。     

切向流作用下直通穿孔管阻性消声器传递损失预测

使用考虑涡黏系数的频域线性纳维斯托克斯方程(linearized Navier-Stokes equations, LNSEs)计算切向流作用下直通穿孔管阻性消声器的传递损失，计算步骤为：运用CFD(computational fluid dynamics)方法求解计算域内的时间平均流动变量，然后将变量映射至声学网格；将声传播介质分为空气和吸声材料，后者等效为具有复声速和复密度的流体，使用频域LNSEs计算声场，最后利用平面波分解法计算消声器的传递损失。计算结果与试验测量结果吻合良好，从而证明了计算方法的正确性。通过数值计算分析了切向流马赫数对不同流阻率和穿孔结构阻性消声器传递损失的影响规律。随着切向流马赫数的增加，消声器在低频域的传递损失有所降低，中高频消声性能变化无明显规律可循；切向流对低穿孔率消声器传递损失的影响大于高穿孔率。     

声源空腔对抗性消声器插入损失的影响

本文根据声能守恒基本原理和四端网络等效电路的方法，将声源空腔对抗性消 声器插入损失的影响进行了若干讨论，利用本文导出的计算结果与其它文献中的计 算结果针对同一单级扩张抗性消声器做了比较，并对此比较作了合理的说明。     

七氟丙烷气体灭火系统沿程压力损失计算方法

七氟丙烷气体灭火系统管网的设计中,不可避免遇到压力损失的问题。本文根据经验提出了一种基于修正系数的七氟丙烷气体管网压力损失的计算方法。这种方法根据伯努利方程与热量损失定律对灭火系统的压力损失方程进行了推导,根据管网参数与设计流量调整了雷诺数,确定了压力损失的系数计算值,对压力损失计算的结果进行了调整,最后通过实验验证了管网的压力损失值,证明该计算方法有效可行。     

用段逼近法计算混凝土收缩与徐变引起的构件预应力损失

因混凝土收缩与徐变引起的预应力损失在总损失中占的比重很大，我国规范中对这部分损失的求解给出了经验公式，本文提出了分段逼近法可求解先张法预应力混凝土轴心受拉构件，任一时间因收缩和徐变引起的预应力损失，并同时考虑了非预应力筋的影响；方法中，把总时间分段，各时段中设应力为常数，求解各时段因收缩和徐变引起的预应力损失，再叠加求总损失，这样，可求出预应力损失较精确值，混凝土收缩与徐变求解采用了作者导出的一组公式。／     

用分段逼近法计算混凝土收缩与徐变引起的构件预应力损失

因混凝土收缩与徐变引起的预应力损失在总损失中占的比重很大，我国规范中对这部分损失的求解给出了经验公式，本文提出了分段逼近法可求解先张法预应力混凝土轴心受拉构件，任一时间因收缩和徐变引起的预应力损失，并同时考虑了非预应力筋的影响；方法中，把总时间分段，各时段中设应力为常数，求解各时段因收缩和徐变引起的预应力损失，再叠加求总损失，这样，可求出预应力损失较精确值：混凝土收缩与徐变求解采用了作者导出的一组公式。     

不忽略一次项损失时望小特性质量损失函数设计

讨论了在一次项损失不能忽略时,一次项和二次项损失系数的确定方法,并且对一次项损失和二次项损失的大小进行了比较分析。研究表明,二次项望小特性质量损失函数只是望小特性质量损失函数的一种特殊形式。最后通过实际问题对研究结果进行了验证。     

存在气流的消声扁管道声学特性的实验研究

消声管道的声学特性通常采用传递损失和插入损失来进行评价。当管道内存在气流时，气流会改变声波在管道内的传播，从而影响其消声性能。同时，气流将在管道内产生再生噪声。当气流流速相当大时，气流再生噪声构成相当强的背景噪声。这种背景噪声使信噪比降低，影响测量精度。本文利用Ｍ－序列相关技术具有抑制背景噪声的特点，对存在气流的消声管道进行了插入损失ＩＬ及传递损失ＴＬ的Ｍ－序列相关法测量。同时，还对同一消声管道进行了传统方法测量，并将这两种测试结果与理论计算值做了比较。Ｍ－序列信号是在周期内具有随机特性的伪随机…     

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.