自适应免疫遗传算法在轮胎花纹节距参数优化中的研究

节距参数优化是低噪声轮胎花纹优化设计的关键环节,针对轮胎花纹节距参数优化寻优时易引发数据爆炸的特点,利用自适应免疫遗传算法(AIGA)的自适应策略和快速搜索能力对节距序列参数和节距比例参数进行优化分析,结果表明该算法的收敛性和效率较遗传算法和免疫遗传算法都有明显的提高,优化结果可降低轮胎花纹噪声水平,具有工程应用价值。     

变节距花纹轮胎噪声特性研究

采用主流的室内实验室转鼓方法对变节距花纹轮胎噪声进行了测试。对具有复杂花纹的乘用轮胎和载重轮胎的噪声频谱特性进行对比分析。对于乘用轮胎,轮胎花纹噪声随着速度的增加呈现一个偏于线性的增长趋势;对于载重轮胎,轮胎花纹噪声反而没有明显的增长趋势,曲线较为平缓;不同品牌乘用轮胎与不同品牌载重轮胎在标准速度下的1/3倍频程频谱曲线变化趋势有较大差异;与手工刻制的等节距轮胎噪声相比,成品轮胎所采用的变节距花纹结构设计有效地降低了各频段噪声峰值;对于变节距花纹成品轮胎,波浪形态横沟设计优于锐角形态,更优于正交形态;连通组花纹结构优于半连通组,更优于不连通组。文章为低噪声轮胎花纹结构优化提供了有意义的参考结论。     

基于遗传算法和TOPSIS法的混合励磁电机齿槽转矩优化

针对切向聚磁型并联结构混合励磁电机（TMPS-HESM）随着励磁电流增加导致齿槽转矩剧增容易引发电机振动噪声的问题，根据齿槽转矩的产生原理，探讨改变转子极靴宽度、磁极偏心距和气隙长度削弱电机齿槽转矩的可行性。借助Maxwell and Workbench and Optislong联合仿真软件建立8极48槽TMPS-HESM模型，运用遗传算法进行全局多目标优化，得到pareto最优解集后使用优劣解距离法(TOPSIS)客观选取最优解。最后对比分析优化前后电机的各项其他性能，结果表明：采用遗传算法和TOPSIS法对电机参数进行优化，能提升电机多目标优化效率，不仅可解决混合励磁电机励磁电流增加导致齿槽转矩剧增的问题，还能有效削弱电机转矩脉动，提升电机平均转矩，在减少电机的振动噪声和提高电机输出转矩方面均取得改善。     

乘用车子午线轮胎泵浦噪声机理的实验-数值混合分析方法

汽车在中高速行驶(乘用车超50 km/h,卡车超80 km/h)时,轮胎噪声取代其他部分噪声成为行驶噪声的主声源。轮胎噪声产生机理主要分为三种:泵浦噪声、振动噪声以及空气动力学噪声。其中泵浦噪声与轮胎花纹设计有关,属于可设计噪声。如何确定声源的频谱特性,进而预测轮胎噪声仍然是一个难点问题。提出一种泵浦噪声源识别的实验-数值混合分析方法。其基本的假设是:花纹横沟在进入地面和离开地面时产生气流,花纹纵沟将该气流收集,在轮胎接地前端和后端辐射出噪声;该噪声的大小与轮胎和地面形成的声场有关,也和轮胎花纹的节距排列有关。所提出的方法包括雕刻花纹轮胎噪声测试、轮胎声场阻抗数值分析、以及声源辨识三部分;通过在频域反演噪声传播过程辨识不同横沟的声源;通过雕刻花纹轮胎进行了噪声实验验证,说明了本方法的有效性。     

基于MLE的滚动轮胎冲击振动噪声仿真分析

提出一种滚动轮胎冲击振动噪声预测的新方法。轮胎滚动接触引发的噪声是道路交通的一个重要课题,引发广泛关注,目前尚没有有效的分析预测方法。提出新方法包括用混合拉格朗日—欧拉描述法(Mixed Logrange Euler Method,MLE)分析大变形滚动接触结构的速度场、加速度场和接触变形。通过欧拉网格和拉格朗日网格的信息传递,完成滚动结构动力学分析。通过将轮胎花纹和胎冠整体三维建模,可以得到连续轮胎表面的加速度场。以参考空间中连续表面的加速度场作为声源,采用声学有限元方法得到滚动噪声的分布预测。实验和仿真结果对比证明本方法的可靠和准确,也证明1 000 Hz以下轮胎的滚动噪声主要是花纹的冲击振动引起的噪声。提出的方法为预测分析轮胎的滚动噪声开辟一条可行的道路。     

大尺寸立方体开槽超声塑料焊接工具头的优化设计

谐振频率、频率间隔性、振幅均匀度是大尺寸超声塑料焊接工具头设计中的几个主要指标。基于工程实际,以工具头纵向长度、槽宽度及槽长度为设计变量,纵向谐振频率和频率间隔值为状态变量,振幅均匀度为目标函数,利用有限元软件ANSYS的参数化分析技术,对大尺寸立方体超声塑焊开槽工具头进行了优化设计。结果表明,该优化方法能很好地解决大尺寸超声塑焊工具头的设计问题,既提高了设计效率,也降低了设计成本。     

轮胎横向花纹沟噪声影响因素的剖析

运用Abaqus对具有横向花纹沟的轮胎滚动进行有限元分析,提取不同速度、气压、载荷、摩擦系数条件下的轮胎花纹沟表面在轮胎接地过程中位移-时间的变形曲线。为分析横向花纹沟的泵吸噪声,建立单个横向花纹沟及其周围的空气域有限元模型,在沟表面加载位移-时间变形曲线,利用FSI方法分析速度、气压、载荷、摩擦系数等使用因素对横向花纹沟泵吸噪声的影响。结果表明：泵吸噪声随着速度和载荷的增大而增大;气压变化均会使泵吸噪声增大;而摩擦系数对泵吸噪声影响不明显。验证FSI方法分析轮胎泵吸噪声是可行的,对后续低噪声轮胎使用和花纹设计具有一定的指导作用。     

衬套型橡胶悬置结构形状的优化方法EI北大核心CSCD

为满足汽车动力总成悬置系统匹配过程中悬置的刚度要求,对悬置中非橡胶填充结构进行优化设计,以长槽的半径r,圆槽的半径R,两槽间的夹角α,长槽的角度β为结构参数,采取正交试验与ABAQUS有限元软件结合的方法,对橡胶悬置刚度进行仿真试验。根据试验结果建立二阶响应面模型,通过谢菲尔德遗传算法进行优化,从而获取非橡胶填充结构参数以满足悬置刚度要求。优化结果与试验验证误差较小,满足设计要求。该方法在橡胶悬置设计阶段具有参考意义。     

空调器室外机导流圈结构参数优化设计

为了满足空调器室外机提高风量和降低噪声的设计要求,基于CFD仿真对导流圈结构参数进行DOE设计与响应面优化分析。以导流圈进口弧半径、弧长对应的圆心角、直线段长度、出口扩压段长度、出口扩压角为优化变量,提高风量为优化目标。结果表明:在给定范围内,进口弧半径和弧长所对应的圆心角对风量的影响最大,直线段长度次之;使用优化后导流圈结构参数组合方案制作的导流圈与原导流圈相比,风量提升约3.5%,相同风量下噪声降低约2 dB(A)。导流圈的优化设计方法可为相关设计提供借鉴。     

不同花纹轮胎噪声辐射特性

轮胎噪声是交通环境噪声的主要来源之一,也是汽车噪声的主要声源。用虚拟模型预测的方法对滚动轮胎的振动辐射噪声进行预测分析。通过对滚动轮胎施加路面简谐激励,获取滚动轮胎表面加速度响应并作为声学分析的边界条件。采用边界元的方法分析不同花纹形式的滚动轮胎在路面激励下振动辐射噪声特性,结果表明花纹形式直接影响着滚动轮胎振动辐射噪声的大小,胎面花纹质量越小,振动辐射噪声越大,研究结果具有工程应用价值。     

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.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

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.……     

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.     

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.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.