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一、前言 噪声源识别是机器噪声控制的关键之一。识别的方法虽多,但均有其局限性。对机器的噪声谱与振动信号谱作常相干函数分析或相关分析,以确定机器哪一个部分为主要辐射声源是困难的,更难定量确定各部分对噪声的贡献。这县因为机器各部件同时振动,彼此耦合,导致声源相干,使得测试分析条件恶劣。而声强 相似文献
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钢管锯切噪声声源分析 总被引:1,自引:0,他引:1
本文以上海宝钢钢管厂ψ1800mm冷锯切割噪声为研究对象,详细进行了在线振动,器材怕测试和锯片振动特性测试。通过振动谱和噪声谱的相关分析及结构模态分析,指出了主要噪声源。 相似文献
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对接式自然散热隔声罩 总被引:1,自引:0,他引:1
对接式自然散热隔声罩夏德荣,周裕德,陈璐(上海环境保护科学研究院)(上钢三厂)一、前言钢铁厂在冶炼过程中所需的氧,系由制氧系统中的透平空压机供气制氧供给,但这种机器为高速、高压,从而产生较高的机器噪声。为了降低这种严重干扰环境的噪声,采用隔声罩是一种... 相似文献
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闪烁噪声是一种非平衡随机过程,其功率谱密度函数在频率低端(f=0)发散,无法直接利用Wiener-Khintchine关系得到它的自相关函数,本文采用“降价-积分”方法,得到了频率源中闪烁调频噪声的自相关函数的解析表达式,根据这一结果,分析了频率稳定度的表征原理,指出了频率稳定度表征的实质是将非平稳过程转化为平衡过程并求取时间平均,最后,通过时域分析得到了闪烁噪声的Allan方差表达式。 相似文献
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航空涡扇发动机喷气噪声分离技术 总被引:1,自引:0,他引:1
涡扇发动机尾喷是飞机的主要噪声源之一,其噪声大小不仅影响飞机的适航取证,更是评价发动机性能的重要指标之一。为了实现发动机的降噪设计,需要将发动机的整机噪声分解到各部件,从而针对部件进行降噪设计。基于三个远场麦克风数据的喷气噪声分离算法,使用MATLAB进行编程,以GE公司的某型发动机噪声静态测试的数据作为输入数据,从发动机整机噪声中分离出喷气噪声,得到喷气噪声声压的自相关谱。根据喷气噪声声压的自相关谱,计算喷气噪声的声压级。分离得到的喷气噪声数据对发动机尾喷的降噪设计有重要意义。 相似文献
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船舶辐射噪声的包络谱中蕴含着轴频和桨叶数等船舶固有特征信息,对船舶目标识别具有重要意义。为了提高船舶辐射噪声包络谱解调性能,提出了基于变分模态分解(Variational Mode Decomposition, VMD)和窄带包络相关的改进DEMON分析方法。首先利用VMD算法代替传统带通滤波器,将船舶辐射噪声信号分解为若干个子带;然后对各子带进行希尔伯特(Hilbert)检波并计算平均窄带包络相关系数,用于衡量信号的包络调制在频域上的非均匀性;最后提取各子带信号包络谱并按照平均窄带包络相关系数进行加权融合,从而得出宽带噪声信号的包络谱。利用该方法对实测不同类型和不同航速船舶辐射噪声信号进行了处理,结果均表明所提方法能有效提高包络谱解调效果,较传统方法更为有效。 相似文献
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本文介绍以TMS320C25信号处理器为核心组成的本艇声检测系统,概述本艇自噪声功率谱计算方法,提取螺旋桨附近噪声特征信号,实现了螺旋桨空化噪声的检测和报警。 相似文献
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This paper proposes an integrated model for multi-machines dynamic lot sizing aiming to produce a single item, considering the energy consumption during the production horizon. The objective is to find, firstly, the optimal lot size as well as the number of machines that satisfy a random demand under given service level and secondly, maintenance plan depended to production planning to minimise the total production, energy and maintenance costs. In fact, the problem of energy consumption is one of the most evoked topics especially with the decision of many governments to reduce theirs (For example France is willing to reduce the total consumption by 20% by 2020). The keys of this study are to consider, firstly, the correlation between the forecasting of demand, the variation of the working machines as well as their production rates under energy constraint and secondly the correlation between the production cadences and the maintenance strategy of all machines. 相似文献
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Group technology is silent on logical operators; it only handles and operators. Here we expand the meaning of the incidence matrix to include logical or operators and show how to use an existing sorting algorithm. Two solutions are suggested for producing the closeness matrices, the starting point of the method developed elsewhere for sorting machines into machine cells and parts into parts families; of these, the second method is recommended for implementation, and this method is shown to be amenable to implementation in multi-dimensional cases, where categories beyond machines and parts can be sorted simultaneously. Thus, the capability of handling a broader spectrum of realistic situations is enhanced, making group technology a more important tool in planning production flow and layout in a modern factory. 相似文献
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传统的分类方法仅仅基于像素光谱特征,不适合于高分辨率遥感影像.本文提出了一种新的基于商空间理论,面向对象的高分辨率遥感影像分类方法,即综合云模型、模糊支持向量机和决策树的分层合成分类技术.针对决定分类效果的两个因素,影像分割和分类算法,分别做出了一些改进.第一,本文提出了一个自适应的基于云模型的区域增长分割策略.第二,... 相似文献
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传统检测扩频信号的声光技术,是将扩频信号建模为随机平稳过程,而扩频信号是被伪随机码调制的周期信号,应建模为循环平稳随机过程。基于声光技术与循环谱相关技术,提出了扩频信号的声光谱相关检测方法。建立了基于声光时间积分的声光谱相关检测模型,分析了当干扰瞄准扩频接收机时,扩频信号在循环频率α=1/Tc的循环谱,给出了循环谱峰的检测公式TcRs1/。仿真实验结果表明,与传统的声光技术检测扩频信号的功率谱相比,在光电检测阵列上检测的循环谱峰,谱峰旁瓣几乎为零,并可多获得约3dB的增益,表明声光谱相关检测方法具有更优异的检测和抗干扰性能。 相似文献
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Prediction and measurement of core losses in a high-speed switched-reluctance Machine 总被引:1,自引:0,他引:1
We describe a procedure for calculating the core loss in high-speed switched-reluctance machines. The technique calculates core losses within a switched-reluctance machine to a high degree of spatial resolution over a wide range of operating conditions. We confirmed the calculations experimentally, using a loss segregation method, and found good correlation. 相似文献
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目的 为满足用户对梳棉机的多维感性需求,多层次提升纺织机械的造型意象满意度和用户满意度,提出一种多目标意象驱动的梳棉机造型设计方法,并展开设计实践与实验研究。方法 首先,设计感性评价实验,通过焦点小组讨论和问卷调研获取用户对梳棉机的感性意象评价均值;其次,采用形态分析法,对梳棉机造型设计要素进行划分,并对代表性样本的造型类目特征进行编码;基于反向传播神经网络(Back Propagation Neural Network,BP-NN),建立梳棉机产品造型要素与用户感性意象评价均值之间的关联映射模型,建立用于造型推荐的样本库,获取单意象维度下的梳棉机造型设计策略;再次,应用层次分析法(Analytic Hierarchy Process,AHP)得到各目标意象维度的权重值,输出多目标意象下梳棉机造型设计策略;最后,结合梳棉机的造型设计实践及感性评价,进一步验证该方法的可靠性和有效性。结果 基于该方法展开设计实践,依据推荐的梳棉机造型设计策略得到的设计方案,在目标感性意象的整体评价得分优于对照样本。结论 该方法有较好的可靠性和有效性,能为企业的新产品开发及设计师的设计实践输出指向具体、操作性强的梳棉机多目标意象设计策略。 相似文献
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HAOZhi-hua MAXiao-jiang 《国际设备工程与管理》2005,10(1):36-41
A new method of fault analysis and detection by signal classification in rotating machines is presented. The Local Wave time-frequency spectrum which is a new method for processing a nonstationary signal is used to produce the representation of the signal. This method allows the decomposition of one-dimensional signals into intrinsic mode functions(IMFs) using empirical mode decomposition and the calculation of a meaningful multi-componentinstantaneous frequency. Applied to fault signals, it provides new time-frequency attributes. Then the moments and margins of the time-frequency spectrum are calculated as the feature vectors. The probabilistic neural network is used to classify different fault modes. The accuracy and robustness oftained during the different fault modes( early rub,the proposed methods is investigated on signals obloose, misalignment of the rotor) . 相似文献
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T. Svensson 《Fatigue & Fracture of Engineering Materials & Structures》1994,17(6):727-736
Abstract— A computer program that creates time histories for use in fatigue tests in servo-hydraulic machines is presented. The time histories can be tailored from certain user specifications, namely the irregularity factor and the level-crossing spectrum. The program is based on the theory of stochastic time series, and the formulae needed for the program are derived in the paper. Problems of optimality are treated both with respect to fulfilment of the specifications and with respect to machine performance. Examples from two fatigue-testing projects, where the program has been applied, are presented. 相似文献