A joint adaptive wavelet filter and morphological signal processing method for weak mechanical impulse extraction

Periodical impulses are vital indicators of rotating machinery faults. Therefore, the extraction of weak periodical impulses from vibration signals is of great importance for incipient fault detection. However, measured signals are often severely tainted by various noises, which makes the detection of impulses rather difficult. As such, a proper signal processing technique is necessary. In this paper, a hybrid method comprised of wavelet filter and morphological signal processing (MSP) is proposed for this task. The wavelet filter is used to eliminate the noise and enhance the impulsive features. Then, the filtered signal is processed by the morphological closing operator and a local maximum algorithm to isolate periodical impulses. To select the proper parameters of the joint approach, i.e., the center frequency, the bandwidth of wavelet filter, and the length of flat structuring elements (SE), a novel optimization algorithm based on differential evolution (DE) is developed. The results of simulated experiments and bearing vibration signal analysis verify the effectiveness of the proposed method.     

An all-digital method for accurate measurements of mechanical deformations

In this paper, an experimental analysis method based on image treatment techniques for the quantitative evaluation of some polycrystal material deformations is presented. This method has been successfully developed for this purpose by adapting and developing algorithms suitable for the images under study. Details of the whole process as applied to a typical example are described and discussed.     

An online adaptive condition-based maintenance method for mechanical systems

This paper proposes an online adaptive condition-based maintenance method with pattern discovery and fault learning capabilities for mechanical systems. The method is mainly based on a subtype of neural network techniques called self-organizing map (SOM). It is able to reduce local clusters from the same pattern and optimize the SOM architecture to further decrease the calculation cost in matching patterns in the neuron fitting process. Moreover, distance analysis and statistical pattern recognition (SPR) on neurons of the SOM are combined to establish rules and criteria for conducting and controlling the discovery and learning process so continuous process as purging prototypes on the map can be avoided. An experiment on condition monitoring of a machine tool test bed demonstrates and validates the effectiveness of the proposed approach.     

An alternative flat scanner and micropositioning method for scanning probe microscope

An alternative flat scanner used for combining a scanning probe microscope with an inverted optical microscope is presented. The scanner has a novel structure basically consisting of eight identical piezoelectric tubes, metal flexure beams, and one sample mount. Because of the specially designed structure, the scanner is able to carry a sample of more than 120 g during imaging. By applying voltages of ±150 V, scanning range of more than 30 μm in three dimensions can be achieved. To improve the reliability of the stick-slip motion, a new method for sample micropositioning is proposed by applying a pulsed voltage to the piezotubes to produce a motion in the z-axis. Reliable translation of the sample has been thus accomplished with the step length from ～700 nm to 9 μm over a range of several millimeters. A homemade scanning probe microscope-inverted optical microscope system based on the scanner is described. Experimental results obtained with the system are shown.     

实例推理方法在机械产品方案设计中的应用

机械产品方案设计是产品设计过程中最关键的设计阶段.提出基于实例推理（Case-Based Reasoning,CBR）的方案设计过程,论述了实现推理的关键技术：实例表示、实例检索和实例修正;从基于实例的产品方案设计过程的研究、CBR与其他推理方法的综合应用以及CBR与创新设计方法的结合3个方面探讨了CBR技术在机械产品方案设计中的主要应用.     

一种优化的精密温度测量方法

为了精密测量水蒸汽的温度,选择了Pt100测温铂电阻,并根据其非线性特性,提出了一种恒流源加电压一频率（V—F）转化器电路的优化测量方法。首先,采用1mA的恒流源,保证流过铂电阻的电流恒定而且足够小,使电阻两端的电压差与电阻值成线性输出关系;其次,采用差分三运放放大电路,将电压信号按比例放大;然后,采用精密的电压一频率转化器,将频率送给微处理器;最后,通过微处理器的采集频率以及简单的软件补偿,得到精密的温度值。试验结果表明,该方法能精密、方便、简单地采集与校准温度。     

机械可靠性分析与设计的一种显式迭代算法

基于改进的一一次二阶知釜对机械可靠性分析和单一设计变量的机械可靠性设计问题,本文提出了计算结构可靠度和确定结构可靠性参数的一种显式迭代算法。与有关文献相比较,这种方法优点是无需解域变换、无需人工计算功能函数的偏导数和无需解结构失效的极限状态方程具有较为简便的计算形式和较高的计算效率,可方便地算出结构的可靠度和结构可靠性参数。本文方法具有一阶计算精度。     

An optical method for detecting mechanical defects on high-grade-finish surfaces

A method for detecting surface defects is discussed. The method is based on analyzing the light scattering function with reference to the problem concerned with automatic control of a fuel cladding surface.     

An integrated method for measurement of diamond tools based on AFM

The measurement and evaluation technology of high precision diamond tools is critically important for supporting the ultra-precision machining. In practical cutting process, the edge profile quality of the diamond tool, including sharpness, micro defects, roughness and tip arc waviness, greatly affects the cutting quality. It is very difficult to measure and evaluate the diamond tool edge profile due to the high precision of tool edge profile and complexity of various measurement parameters. In this paper, an integrated method for measurement and characterization of diamond tools is proposed, which is based on an Atomic Force Microscope (AFM) module. Multiple technical indexes of diamond tools are obtained and validated based on the presented research and cutting experiments, and the evaluation model for each technical index is also proposed. The integrated measurement equipment, including an AFM, precision adjustment device and aerostatic bearings, has been established based on the accuracy requirement of measurement parameters. The edge sharpness, micro defects, surface roughness and tip arc waviness have been obtained based on the evaluation model and experimental data. The experimental results show that the measurement accuracy meets the requirements of the comprehensive evaluation of the diamond tool edge profile. The research work will also contribute to the development of ultra-precision machine.     

Measuring the mechanical recoil impulse of a polymeric target upon impact of a high power electron beam

A method for measuring the mechanical recoil impulse of a target produced by the relativistic electron beam of the Calamary accelerator is described. A detector based on a piezoelectric sensor is used in measurements. Results of measurements are presented for the mechanical recoil impulse produced by the relativistic electron beam with an energy as high as 300 keV, a current of up to 30 kA, and a duration of ~100 ns that is incident on an epoxy target. The energy flux density on the target surface is varied in the range of 1–10 GW/cm². The maximum measured impulse value is 0.32 N · s at an energy flux density of 10 GW/cm² (an energy fluence of 810 J/cm2).     

An active method for the control of mechanical systems in the presence of unmeasurable forcing

The paper shows how the response of an inertial system to an unknown external force can be controlled. An estimate of the external force is derived via acceleration and control force measurements and this prediction is used to generate an actuator force equal and opposite to the external force.Compensation for actuator dynamics is discussed and the ability of the method to deal with harmonic, random and system generated (linear and non-linear) forces is considered.     

A signal interpolation method for Fabry–Perot interferometer utilized in mechanical vibration measurement

In this investigation, a self-developed signal processing method for Fabry–Perot interferometer is proposed which can be utilized for high-speed dynamic displacement measurements, e.g. mechanical vibration measurements. The lookup table (LUT) integrated with the interference intensity equation has been employed for the interpolation processing of interference signals. With the aid of this method, the interpolation error has been reduced by 40% in comparison with that resulting from the commercial sinusoidal signal processing module. By operations of Fast Fourier Transform (FFT), the displacement measurement distribution can be converted into the frequency spectrum diagram. The interpolation resolution of the proposed interferometric displacement measurement system is about 0.1 nm. Experimental results demonstrate that this interferometer system is available for measuring frequencies till 2 kHz where its corresponding amplitude is 0.15 μm.     

存在模糊信息时机械零部件的优化设计

为使机械零部件的设计更符合实际,更合理,根据模糊数学及优化设计理论,探讨了机械零部件的存在模糊信息时的优化设计数学模型及求解方法,并结合该理论对V带传动设计进行分析,得到了比普通优化设计更为理想的设计结果.其结果证明了该方法的可行性与实用性.     

An emissivity-corrected method for the accurate radiometric measurement of transient surface temperatures during braking

The main difficulty encountered in brake disc infrared temperature measurements is the lack of knowledge of the disc surface emissivity, which is nonuniform and varies during braking. To provide information on the nonuniformity and variations of emissivity, brake disc surface temperatures were investigated by an original two-colour fibre optic pyrometer and an infrared camera. The first result is the measurements of the accurate surface temperature. Besides, it is shown that the local emissivity varies with friction due to modifications of surface properties. Thermal phenomena observed on the disc track are correlated with temporal changes of normal and tangential frictional forces.     

浅谈动态轴计量汽车衡机械结构的设计思路

本文介绍了动态轴计量汽车衡的机械结构，包括基础与秤台、限位及传感器压头的设计思路及方法，对国内常见的动态轴计量汽车衡的机械结构形式作了简单的分析与比较，并结合自己的工作经验提出了一些个人的观点。     

高炉冷却系统热负荷在线监测系统

本文详细地叙述了系统的组成、工作原理和功能。温度、流量检测采用自行设计的采集装置,成本低,安装简便,可靠性高,满足了测量要求。采用该监测系统可实时地监测高炉冷却系统的水温差、流量及热负荷,为高炉安全生产提供依据。     

An optical non-contact measurement method for hot-state size of cylindrical shell forging

Using the present method the inner diameter cannot be measured. So an optical non-contact measurement method for measuring inner and outer diameters of cylindrical shell forgings is proposed. Firstly, an infrared dual-color temperature measurement system is devised based on the three-level interference filter. Secondly, the relationship between temperature and size is derived. Using this relationship the inner diameter is measured by combining the outer diameter and temperature. The outer diameter is measured by laser scanning technology and the temperature is measured by infrared temperature measurement technology. Thereby the measurement for hot-state size of cylindrical shell forging is achieved. Finally, the measuring method is feasible according to the experimental result.     

金属水溶液电解电极电流在线测量方法

在金属的水溶液电解提取过程中,电极短路会降低电解电流效率,增大电耗,降低阴极产品的质量.电极电流的变化是监测电极短路的最有效方法.由于电解环境恶劣、电磁场分布复杂,电极数目众多,目前缺少有效的电极电流在线测量方法.本文提出一种测量电极电流的方法,其采用线性霍尔传感器实时检测电极下的磁感应强度,利用霍尔电势、磁感应强度和...     

Dynamic accuracy measurement system for mechanical wristwatch

The time shift of mechanical watches is caused by individual differences (manufacturing error), environmental temperature, magnetism, posture, impact force and dynamic environment. The easiest and clearest method of measuring the accuracy of mechanical watches is to measure the time shift by comparing it with the reference time. The disadvantage of this method is that it can only measure accuracy at a certain time. Another method for measuring the accuracy of mechanical watches uses a watch timing machine that obtains the vibration sound of a watch using a microphone and calculates accuracy in the short term. This method can measure the change in watch accuracy over time. However, it cannot be used to measure accuracy in a dynamic environment because the watch timing machine is large and there is a sound noise. To clarify the accuracy of mechanical watches in dynamic environment, this study developed an accuracy measurement system which can be carried and measure in a dynamic environment. This study monitors the movement of a partly constituted mechanical watch using a photo interrupter and develops a method to calculate the rate and amplitude of a balance wheel from the output value of the photo interrupter. The validity of the developed system is verified by comparing the time shift of the system and radio clock time over the long term. The developed system, can be used in a dynamic environment because it consists of the photo interrupter in the watch case. Moreover, this study conducted measurements under forced vibration using vibration generator and during walking with the system.     

基于SVD的直线电机动子位置的高精度测量方法

针对直线电机动子位置测量的高精度和实时性要求,提出了一种基于奇异值分解(SVD)相位相关算法的高精度图像测量方法。通过直线电机动子上的高速相机采集相邻栅栏图像,采用单行抽样栅栏条纹数据,再利用相位相关技术得到相邻栅栏图像的相位相关矩阵,进而利用SVD得到水平位移相位矢量。通过相位解缠算法和最小二乘法线性拟合得到二幅栅栏图像的亚像素位移量,将相邻栅栏条纹的像素位移值和动子实际位移进行标定,结果用于直线电机动子位置测量系统标定。并且进行傅里叶变换前采用Hanning窗抑制频谱泄露,提高匹配精度。实验结果表明,该直线电机动子位置的亚像素测量方法可以满足实时性和高精度测量要求。