非局部弹性杆固有频率求解的传递函数法

基于Eringen提出的非局部弹性模型，采用幂指数型核函数，导出直杆的振动方程，该振动方程与应用Eringen非局部微分本构关系得到的杆的振动方程一致，并应用传递函数法，进行了直杆的动力学分析，计算了它的固有频率和相应振型，结果表明本文方法具有一般性和通用性，并且求解问题过程统一，精度高，能够处理多种边界条件。     

Elastic Bar Transfer Function Determination Using Two-Point Strain Measurements

This paper presents an experimental method of determining the elastic bar's transfer functions in the form of formulas. The method is based on the two-point measurement of the elastic strain waves propagating inside the bar, the spectral analysis of these waves, and making use of the general solution of the equation of movement of the bar in the frequency domain. The determined transfer functions of the bar are used for impulsive strain waveform reconstruction by means of deconvolution in the frequency domain and for the validity check of the reconstruction. The application of this method to the reconstruction of impact pressure waveforms is presented.      

基于传递函数的机动车驾驶员各驾驶环节疲劳分析

把传递函数引入到驾驶行为各环节的分析当中，建立了函数模型。通过时域分析指出驾驶疲劳的量化特征。     

Measurement of the Discrete Modulation Transfer Function

Abstract

The development of a unique discrete modulation transfer function (DMTF) [1] has solved the previous problem of multivalued modulation transfer function associated with the non-isoplanatic nature of discrete systems. This paper proposes two methods for the measurement of the DMTF and shows that the use of the DMTF makes the performance analysis and measurement of discrete systems easier.     

基于传递函数的发动机附件振动预测

阐述整车异常振动噪声的排查过程,确定问题为发电机和空调压缩机组件1阶共振。通过模态试验和有限元分析结果对比,保证仿真模型准确性,为下一步传递函数分析提供输入。通过测试第三主轴承盖到空压机远端处传递函数,得到结构阻尼信息。采用相同阻尼值,对空调压缩机支架更改前后传递函数进行对比,改进后第1阶模态共振频率提高,同时幅值也有降低。对改进后样件进行整车试验,结果表明,在默认激励保持不变基础上,可通过传递函数来间接反应最终响应结果,从而验证可以利用传递函数对发动机外附件振动进行预测。     

Methods of Measuring the Modulation Transfer Function of Photographic Emulsions

The different methods of measuring the modulation transfer function of photographic emulsions are discussed in four sections; (i) sine wave methods, (ii) Fourier transformation of the line spread function, (iii) coherent light processing methods, and (iv) calculation from scattering measurements. Particular attention is paid to the effects of the non-linearities of the photographic process, and to the effects of film grain noise on the measured transfer function. A brief discussion of the related microdensitometry is also included.     

调相型容栅传感器传输函数的误差分析

本文讨论了容栅传感器传输函数对示值误差的表达,分析了传输解调函数的不同组合对误差的影响,并对不同的解调函数在一个空间周期内求得了相等的最大误差。     

Effect of Truncation of Noisy Line Spread Function on the Computed Optical Transfer Function

Theoretical consideration is given to the error of the optical transfer function caused by noise and truncation of the measured line spread function. The error due to noise is shown to be an increasing function of the scanning range of the line spread function. An optimum scanning range is found to exist that minimizes the total error resulting from noise and truncation. Numerical calculation is presented for the case of an aberration-free circular aperture and the change in total error with varying scanning range and noise level is illustrated.     

切削过程传递函数辨识的新方法

本文提出一种切削过程传递函数辨识的新方法,即用输入脉冲响应位移使切削过程传递函数从切削系统中解耦来测量内调制动态切削力系数.讨论了提高测量信噪比的可行方法,用指数窗函数压缩切削力测量中的噪声,其带来的误差是可以忽略的.最后示出了不同切削参数下动态切削力系数的测量值,并进行了简要的讨论.     

Modulation Transfer Function Assessment for Sampled Imaging Systems: A Generalization of the Line Spread Function

Abstract

The line spread function is a classical figure of merit for the modulation transfer function assessment of an optical system. However, this test cannot be directly applied to sampled imaging systems as they often exhibit aliasing effects. The purpose of this paper is to define a new figure of merit which allows the characterization of the transfer of all spatial frequencies even those which are placed after the Nyquist frequency. An experiment has been carried out to demonstrate the effectiveness of this new test.     

电阻应变数据采集系统传递函数的评价

提出了电阻应变数据采集系统传递函数的一种辨识方法,给出了详细技术过程,包括:电阻应变阶跃激励源的构建与赋值,电阻应变阶跃信号波形的获取,应变放大器恒定时间延迟的测量估计,用等效采样方式获取电阻应变数据采集系统的阶跃响应序列,激励序列和响应序列的时序统一与合成,用一种特殊白化滤波器的最小二乘法进行电阻应变数据采集系统传递函数辨识等。在一组实验中的传递函数辨识应用,证明了该方法的有效性及可行性。该方法可用于电阻应变数据采集系统动态特性的计量校准,及其传递函数辨识。     

传递函数法在非局部弹性梁动力学分析中的应用

采用传递函数方法进行了非局部弹性梁的动力学分析。非局部弹性梁内一点的应力与梁某一区域内任意一点的应变均有关系。本文基于Eringen的非局部弹性积分型本构关系,采用幂指数型核函数,利用Laplace变换导出梁的四阶偏微分形式振动方程,通过定义状态向量,将控制方程化为一阶微分方程组,并采用传递函数方法进行了求解,针对两种边界条件给出了非局部弹性梁的固有频率和固有振型。结果表明,同阶频率下,非局部弹性梁的频率比局部梁的频率低,振型基本一致。     

The Calculation of the Optical Transfer Function

In previous OTF computer programs, various geometrical optical aspects of image formation appear often to have been ignored. The neglect of factors associated with anamorphotic imagery, pupil aberrations and vignetting, and a shift of focal plane can lead to considerable errors in the computed values of the transfer function, particularly for high-aperture or wide-angle systems. In addition, the numerical integration processes employed have not always been entirely satisfactory in terms of efficiency, generality, and convenience.     

识别传递函数参数的一种广义最小二乘法

线性动力学系统的频响特性的量测误差具有相关性,用最小二乘估计求得的传递函数系数有偏.为此,本文用广义最小二乘法导出识别传递函数参数的迭代算法,并用数值模拟法产生强噪声污染的频响函数数据,用它作识别计算.结果表明本文建议的算法比最小二乘法的精度有明显提高,计算量也不大.     

Measurement of the Transfer Function of Hot-Wire and Hot-Film Turbulence Transducers

A microwave simulator for controlled variation of air-flow velocity in the dc to 500 kHz frequency range is described. The simulator serves for measurement of the transfer function of hot-wire and hot-film transducers used in turbulence research. The microwave simulator consists of an X-band power modulated klystron which delivers electromagnetic energy to the transducer, mounted in a small-size calibration wind-tunnel supplying the transducer mean flow velocity (in the 0 to 80 m/s range). Experimental results are given for the absolute value of the transfer function in a 60 dB range, of a hot-wire tungsten transducer (5 micron diameter X 1 mm long) and of a platinum-plated quartz hot-film transducer (25 micron diameter × 0.5 mm long).     

Three-dimensional Optical Transfer Function for Weak Aberrations

Abstract

The phase variations of the three-dimensional optical transfer function for incoherent optical systems with weak aberrations of different types are developed in algebraic form. Both single Seidel terms and Zernike sums are considered.     

基于离散传递函数的线性跟踪系统的控制算法

给出一种基于离散传递函数的线性跟踪系统的控制算法，并在离散传递函数的零点都在单位圆内的情况下证明了这种控制算法的控制量序列是有界序列，从而保证了这种控制算法的可行性，将这种算法应用于ATP粗跟踪系统中，对某飞机的一组方位角数据的拟合轨迹进行跟踪仿真，获得了满意的跟踪结果。     

具有随机传递函数的滤清器的噪声预测

应用矩阵摄动理论、矩阵微分理论、Kronecker代数和矩阵函数的二阶矩技术,提出具有随机传递函数的滤清器的噪声分析方法。在考虑有关大气介质的不确定因素情况下,在时间和空间域内清晰地描述了具有随机传递函数的滤清器的随机响应,并获得了具有随机传递函数的滤清器出声口处随机响应前二阶矩的A计权声级。     

阻抗管中吸声系数的传递函数测量法

介绍了在阻抗管中采用传递函数法测量材料吸声系数的原理，详细介绍了使用双传声器进行测量的方法，指出了测试的频率范围取决于阻抗管的管径大小和传声器布置的位置。