应用VA One统计能量法预报户内变电站噪声探索

城市户内变电站的建立解决了城市电力需求，同时产生的噪声对环境也造成了严重污染。在城市变电站设计初期预估其噪声声压级水平(SPL)，及时采取降噪措施显得尤为重要。应用VA One软件，基于统计能量分析方法建立声学仿真模型，对某典型户内变电站的主变室内外空间声场进行模拟。探讨声源声压级强度、吸声墙高度和吸声系数对噪声场声压级的影响规律，为进一步对户内变电站噪声预报和降噪设计提供参考。     

空间吸声体降噪工程技术经济效益的综合评价与探讨

吸声降噪是噪声控制技术领域中的一个重要方面.七十年代以来,随着我国环保事业及噪声控制技术的迅速发展,以板状空间吸声体为主的各种空间吸声体在工厂吸声降噪工程中得到了日益广泛的应用,为改善工人劳动条件,保护城市环境安静,节省吸声降噪工程投资,提高技术经济效益,改善建筑装饰效果等方面均起到了较为显著的作用.     

关于“户内变电站主变压器室消声墙”工艺标准的研究

近年来,随着城市建设的快速发展,城市的建设进入了快车道,城市区域扩大、居住人口增多,用电负荷大幅度增加,原有电网已无法满足要求,城市中户内式变电站不断增多,工业和居民用电量增长很快。特别是夏季的用电高峰期间,变电站主变压器在大负荷、连续高温情况下,产生的噪声较大,连续时间长,尤其是居民密集区的户内变电站的噪声引起的居民投诉颇多,因变电站噪声等影响而引起的民事纠纷增多,同时也给城市新建变电站的规划增添难度,如何解决好城市变电站噪声问题已是当前城市电网建设亟需破解的一道难题。本文针对户内变电站的主要噪声源主变压器,采用在变压器室内墙做消音墙的方法,从消音材料、结构形式、施工工艺等多方面考虑,结合现场实际施工情况,最终设计出主变压器室消音墙的施工方案,显著降低噪音强度,以达到解决城市户内变电站的噪音扰民问题。     

前向式多叶片离心通风机噪声机理及治理研究──三、导流吸声结构及试验研究

本文首先阐明了前向式多叶片离心风机导流吸声降噪结构的降噪机理和设计思路，并结合该类型风机的结构特点设计出包括进口导流吸声锥、电机根部导流吸声锥以及出口导流吸声蜗舌三项措施联合而成的一套独特的风机导流吸声降噪结构；然后，在试验研究的基础上，对导流吸声结构的结构形式及参数进行了优化，确定出降噪效果最佳的措施各参数，最终实现较好的降噪效果。     

前向式多叶片离心通风机噪声机理及治理研究

本文首先阐明了前向式多叶片离心风机导流吸声降噪结构的降噪机理和设计思路，并结合该类型风机的结构特点设计出包括进口导流吸声锥、电机根部导流吸声锥以及出口导流吸声蜗舌三项措施联合而成的一套独特的风机导流吸声降噪结构；然后，在试验研究的基础上，对导流吸声结构的结构形式及参数进行了优化，确定出降噪效果最佳的措施各参数，最终实现较好的降噪效果。     

微穿孔板在抽油烟机噪声控制中的应用

目的:针对抽油烟机的噪声控制问题,采用进气通道吸声的方式对抽油烟机的噪声进行控制。方法:根据抽油烟机的噪声特性分别设计了单层和双层微穿孔板共振吸声结构并进行了噪声和空气性能测试。结果:变空腔微穿孔共振吸声结构降噪效果显著,采用单、双层微穿孔板共振吸声结构降噪的平均降噪量分别能达到1.7 dBA、2.8 dBA,而空气性能改变量不超过5%。结论:变空腔微穿孔共振吸声结构具有较好的宽频吸声特性,双层微穿孔板共振吸声结构比单层结构吸声频带更宽。     

柔性吸声隔音降噪纺织复合材料

柔性吸声隔音降噪纺织复合材料由于能够提供比传统纺织品更宽的吸声域,比传统降噪材料轻薄、柔软、透气和易加工而备受关注。开发基于纺织材料的聚合物复合材料是近年来噪声控制领域的热点研究方向之一。本文从新型纤维、降噪功能填料和柔性降噪纺织复合材料3个方面综述了国内外柔性吸声隔音纺织品的研究进展,并归纳总结了柔性降噪纺织品的制备方法,进一步对柔性吸声隔音降噪纺织品的发展趋势进行了展望。     

铝纤维板的复合结构吸声性能分析

为了解决变电站低频噪声问题,研制两种铝纤维板复合结构材料。首先基于阻抗管法分析铝纤维的面密度和空腔对低频吸声性能的影响,然后将铝纤维板分别与聚酯纤维、亥姆霍兹共振器进行组合形成复合结构材料,接着分析复合材料的低频吸声性能。结果表明,铝纤维的面密度对吸声系数影响较小,而增大空腔厚度可一定程度提高铝纤维板的低频吸声系数,但100 Hz处吸声系数仍然不理想;铝纤维板-聚酯纤维复合结构和铝纤维板-亥姆霍兹共振器复合结构相较于铝纤维板低频吸声性能均有很大的提高,特别是100 Hz的吸声系数最高可达到0.9以上,可用于变电站低频降噪。     

空气和水声吸声材料研究现状

吸声降噪是人们普遍采用的降噪方法。叙述了空气声以及水声吸声材料的种类、性能特点，改善材料吸声性能的方法，以及吸声材料的研制现状与发展趋势。     

车辆室内噪声的统计能量分析优化仿真

根据统计能量分析的方法,建立国内某种商务车的SEA模型,在其室内噪声的控制和预测中,应用优化设计方法对隔声与吸声方法的使用进行了优化设计,SEA仿真结果表明,其降噪后的结果与实际中有着良好的一致性,所选择的降噪方法是可行的.     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。