The Foundations of Multivariate Analysis

In robust design studies, the important noise factors are varied systematically in off-line experiments and their interactions with control factors are investigated. The choice of the noise variable settings is extremely important in being able to achieve the goal of robust design studies. However, the noise distributions are rarely known, and the choices are often based on convenience. This article demonstrates some of the unintended and undesirable consequences of such choices, including identification of small dispersion effects as important, missing of large ones, and issues with parameter optimization. The main contribution of the article is to propose an alternative method of analysis for identifying important dispersion effects, one based on separate analysis for each noise factor. The method is tailored for situations with crossed-array designs. There are, however, still challenges associated with choosing the control factor settings to achieve robust performance. Further, there are difficulties with the use of combined arrays in such cases. The focus of the article is on direct modeling of the responses but implications for mean–variance analyses are also discussed.     

生态型住宅小区的噪声控制对策

生态型住宅小区的试点建设在于引导创建健康、舒适的居住环境，实现社会、经济、环境效益的统一，其噪声控制问题是重要内容之一。文章从标准要求着手，通过分析小区内外噪声源，提出了控制对策建议，可供环境评价、建筑设计和竣工验收参考。     

调节阀空化噪声数值分析

针对工程实际应用中调节阀普遍出现的空化及其产生的噪声问题,采用基于流声场声振耦合的数值分析方法,研究了不同开度与不同压差对空化噪声的影响。调节阀的空化噪声是阀门产生噪声的原因之一,传统的方法很难准确的分析和预测这种噪声。首先利用CFD软件计算调节阀内的三维瞬态流场,然后将瞬态流场的计算信息作为声场计算的激励信号施加到调节阀阀体上,最后基于声振耦合的方法对其进行声学响应计算。结果表明：本文所研究的调节阀空化噪声随着开度的增加呈先减小后增大的趋势;当调节阀进出口压差增大时,空化噪声也随之增大,在出口压力为0.45MPa时,噪声达到了93.2dB;通过数值模拟得到云图可作为分析噪声产生位置的依据,计算得到的噪声大小可作为判断空化程度的依据,为声学检测阀门空化程度提供数据支持。     

Space-Filling Designs for Robustness Experiments

To identify the robust settings of the control factors, it is very important to understand how they interact with the noise factors. In this article, we propose space-filling designs for computer experiments that are more capable of accurately estimating the control-by-noise interactions. Moreover, the existing space-filling designs focus on uniformly distributing the points in the design space, which are not suitable for noise factors because they usually follow nonuniform distributions such as normal distribution. This would suggest placing more points in the regions with high probability mass. However, noise factors also tend to have a smooth relationship with the response and therefore, placing more points toward the tails of the distribution is also useful for accurately estimating the relationship. These two opposing effects make the experimental design methodology a challenging problem. We propose optimal and computationally efficient solutions to this problem and demonstrate their advantages using simulated examples and a real industry example involving a manufacturing packing line. Supplementary materials for the article are available online.     

汽车制造厂空压机站及冷却系统的噪声治理

空气压缩机和冷却塔噪声是汽车制造厂的强噪声源之一,如何有效的控制其对外界的影响,是汽车制造厂在环境保护方面应对的问题。介绍重庆某汽车制造厂空压机站和冷却系统噪声治理过程中所采取的措施及治理效果。     

Online automatic process control using observable noise factors for discrete-part manufacturing

Robust Parameter Design (RPD) has been used as the primary technique to reduce process and product variability. The offline choice of appropriate control factor settings allows RPD to ensure that noise factors have a minimum influence on responses. In this article, an alternative methodology of automatic process control is proposed, that is, controllable factors are adjusted online based on in-process observations of noise factors. A cautious control strategy, which explicitly considers the observation uncertainty in adjusting the settings of controllable factors, makes the system performance consistently more favorable when compared with the certainty equivalence control strategy and RPD. On the other hand, RPD can be considered a special case of automatic control laws using a constant control setting during production. A case study of a sheet-metal stamping process demonstrates that the implementation of the proposed method in an industrial facility can lead to significant quality improvements.     

用边界元法研究不同顶端声屏障的性能

交通噪声已成为城市主要污染源之一.目前控制交通噪声的主要措施是采用声屏障结构.考虑各种变化因素（表面声学特性、频率等） 的影响,应用边界元方法对不同顶端结构的声屏障降噪性能进行了计算研究.通过数据的对比分析,结果表明：作全吸收处理的树杈形声屏障整体降噪效果最好.     

船台生产作业噪声治理及声屏障降噪效果预测

针对造船厂船台生产作业噪声治理及降噪效果预测难的问题,提出船台噪声的治理方法。以某造船厂船台噪声治理为例,结合某造船厂船台噪声治理实例,提出船台噪声的治理方法,并针对其噪声特点,对噪声源进行建模,预测了主要治理措施的降噪效果。结果表明,造船厂船台生产作业噪声需从声源、声传播途径及生产作业管理等多方面进行综合治理;除降噪效果外,声屏障的设置还需考虑施工可行性、社会因素以及经济性等实际情况;对于船台生产作业噪声等分布范围广、密度大、垂向位置高的声源的模拟预测,需根据声源实际工况进行针对性建模。研究可为船台生产作业噪声等类似噪声源的噪声治理和预测提供参考。     

汽车车门密封性能控制与风噪声改善

汽车车门密封性能是整车风噪声水平的重要影响因素,分析汽车车门主要部件密封机理,提出相应泄漏控制方法;结合某款SUV车型后侧窗风噪"泄漏声"问题,通过车门密封优化,消除异常风噪声,主观评价及客观测试均达到改善目标。     

Nondestructive evaluation of ferromagnetic materials by a “magnetometer like” experimental arrangement

The paper presents experimental results regarding the influence of mechanical stresses and thermal treatments on the Barkhausen noise and magnetization characteristic of MolyPermalloy and MuMetal ferromagnetic samples. The samples are different in stress magnitude and localization and in their thermal history. The level of Barkhausen noise and the changes in magnetization characteristic are estimated by measuring the sensitivity and transduction gain of magnetometer like coils configurations which employ the studied ferromagnetic samples as their nonlinear ferromagnetic cores. The present method is unique in the sense that the two factors (one factor is related to the internal magnetic noise, and the other one is related to the form of the magnetic characteristic) are obtained by employing a single relatively simple experimental arrangement. Various types of stresses, which are different in magnitude and localization, become distinguishable one from the other, when considering their differential effects on the two factors. Several possible experimental arrangements are shown.     

降低轴流风机噪声的研究

针对本公司生产的轴流式风机存在噪声偏高的问题进行了研究。通过分析，找出产生噪的主要原因，提出了降低噪声的具体改进措施，为这种风机的降噪改进设计做出了基础性的工作。     

《货车怠速空压机进气噪声控制研究》

多种噪声源识别手段表明某载货汽车怠速异响噪声源为空压机进气噪声,对此,在空压机进气管上设计了扩张式消声器和干涉式消声器。包含进气消声器、空压机进气管、发动机进气管和空滤器的进气系统声学有限元分析结果表明,设计消声器的传声损失显著。在此基础上,对扩张式消声器和干涉式消声器试制了样件并进行了实车降噪效果验证。结果表明,设计消声器均能有效地降噪且干涉式消声器效果优于扩张式消声器。由于设计的干涉式消声器结构上的不足和空压机与发动机共用进气系统的特点,对干涉式消声器进行了工程化改进设计。工程化的干涉式消声器的声学有限元传声损失和实车降噪效果依然显著。干涉式消声器工程化设计虽然消声效果比干涉式消声器效果略差,但避免了其管路长易憋气的缺点。最后,对干涉式消声器工程化设计进行了储气筒升压测试,虽然升压时间略增加,但远优于国标要求。     

发动机排气噪声主动控制的LMS算法仿真研究

发动机排气噪声有源控制算法有多种,不同的算法因其复杂程度不同实际的控制效果也不一样。为了找到一种更有效的控制算法,用MATLAB建立Simulink仿真模型对LMS算法进行仿真,从仿真效果判断出在误差通道客观存在的情况下LMS算法的局限性并对LMS算法进行了改进,取得了较好的控制效果。     

2.4 L汽油机噪声及其频谱特性的影响因素分析

对结构相同但材质及工艺不同的A、B两台样机进行噪声水平对比分析的基础上,着重分析影响样机A噪声频谱特性的主要因素。结果表明：与着火频率相关的发动机基频振动和进排气侧表面的辐射噪声是主要噪声源;而混合气浓度以及点火时刻虽影响中高频范围的燃烧噪声,但对基频成分无影响。转速越高、负荷越大,基频峰值越高。因此,改善进排气系统的结构刚度、各缸均匀化的控制策略以及曲轴的减振是降低整机噪声水平的有效措施。     

一种基于梯度下降的次级通道在线建模有源噪声控制算法

针对前馈式有源噪声控制系统中次级通道在线建模精度低及建模信号与控制信号相互影响的问题,提出一种基于梯度下降的次级通道在线建模有源噪声控制算法。根据主动控制环节与建模环节的误差能量比,分别调节两个环节的收敛因子,利用主动控制收敛因子和建模收敛因子的调节方式减小二者的相互干扰。在建模收敛因子调整过程中引入梯度下降方法,对步长设置检测阈值,当步长达到阈值,对收敛因子采取梯度变化。仿真结果表明,针对混频信号的有源噪声控制,这种算法对比已有算法能获得较快的建模收敛速度和较低的稳态误差,且可以获得较高的降噪量。     

基于空腔流动特性的汽车侧窗风振噪声控制方法研究

利用简单空腔模型对串联空腔控制风振噪声方法进行了机理分析,得出抑制空腔噪声主要通过气流导出效应和能量耗散效应的结合。基于此机理,提出了一种汽车侧窗风振噪声的控制方法,即在B柱上开凹槽,使凹槽和后窗开启时的车内空间形成一个串联空腔。采用大涡模拟(LES)的计算方法对其进行数值模拟,结果表明开凹槽后可以有效的抑制风振的产生。并对凹槽的尺寸进行了优化研究,计算结果表明L/D=4凹槽的降噪效果最明显,最大降幅达到14dB。     

户外变电站噪声预测及优化控制设计

变电站噪声会对周边环境产生影响,针对如何降低其影响,开发了“变电站环境噪声仿真分析及优化控制系统”软件,然后通过对噪声源、建筑物、敏感点、树木以及其它障碍物的整体仿真分析计算,优化新建变电站的规划设计方案和运行变电站的噪声治理方案。该方法能够提高噪声控制效果,降低工程造价,避免噪声控制设计过程中的随意性和盲目性,具有一定的推广应用价值。     

Taguchi parameter design by second-order response surfaces

The application of response surface methods for the design and analysis of Taguchi parameter design experiments is extensively discussed in a paper by Myers, Khuri and Vining (The American Statistician, 46 , 131–139 (1992)). To illustrate the use of response surface analysis, much attention is given in that paper to a response model that is linear in the noise factors. In practice, such a model is often of limited use, since quadratic effects of, or interactions among, noise factors cannot be modelled. In this paper, second-order response surfaces in the noise factors are considered, so that these limitations are eliminated. Furthermore, the idea of design factors with noise is explained and it is shown that these can also be included in the model for the process variance. An example of a Box–Behnken experiment with noise factors is presented to show the usefulness of these extensions in practice.     

风洞一维离散噪声ANC技术研究

风洞噪声不仅直接影响人们的身心健康,更重要的是较大的背景噪声还降低了风洞声学试验能力和试验精度,降低风洞噪声已成为风洞建设中攻关的关键技术问题。因此提出基于Fx-LMS自适应控制算法实现一维离散噪声主动控制,实验结果表明其能有效解决单波麦克风失匹配带来的误差,减小权系数变化对系统的影响,提高系统收敛速度;根据优化后的算法参数,在0.55 m×0.4 m声学风洞消声室进行管道噪声主动降噪实验,获得理想的降噪效果。     

Advanced Data Reduction and Control of High-Precision Low-Temperature Experiments

No Heading Advances in low-temperature techniques allow us to measure temperature with a precision approaching one part in 10¹¹. Using an rf-biased Josephson-array voltage source, we can control the power dissipated in electric heaters to the same level. At this level of precision, the algorithm used for thermal control and its sensitivity to the non-white character of the input noise become important factors limiting the temperature stability of fundamental physics experiments. We consider the problem of measuring slowly changing data in the presence of both while noise and sudden, short noise spikes. Such data is obtained in high-resolution experiments in earth-orbit, where the thermometers are struck and heated by charged particles. We devise control schemes that improve upon traditional methods. Specifically, a proportional-integral/proportional controller has a better step response, and applying a Kalman filter to the input signal significantly decreases noise injected by the feedback loop. We also describe a new algorithm for spike removal that is robust and has a fixed worst-case execution time. It is significantly faster than the algorithm used in experiments previously flown in space.PACS numbers: 84.40.Xb, 84.40.Ua, 89.20.Ff, 89.20.Kk