Research on the Information Fusion Method of Oil Diagnosis and Vibration Diagnosis Based on the Rough Sets Theory

The improved method has been presented for knowledge reduction in rough sets （R-S） theory, when R-S is used to model the information expression of oil and vibration diagnosis. Therefore, the typical fault simulation tests of rolling bearings have been made, and the application method of R-S has been also analysed in this paper. The diagnosis model of holding rack fault in rolling bearing was presented based on the improved reduction method. It is suited to information fusion to combine information when oil analysis and vibration analysis are combined for fault diagnosis.     

Thin, low frequency, high displacement actuator panels

 An advanced type of thin, high displacement, low frequency actuator panel is being developed for in-air active vibro-acoustic control applications. The 10 cm×10 cm actuator panel consists of cymbal-type flextensional sub-elements placed mechanically and electrically in parallel with each other between two stiff cover plates. The total thickness of the actuator panel is 6.35 mm. Two panel designs are currently under investigation. One consists of sixty-four 12.7 mm diameter cymbals in an 8×8 square arrangement. It is intended for use in the frequency band from 1 kHz to 10 kHz. The other panel has sixteen 25.4 mm diameter elements in a 4×4 square configuration and is designed for use below 1 kHz. Laser Doppler velocimetry (LDV) measurements show peak displacements on the order of 1 μm or more are obtained when driving the panels at one Volt at their respective resonance frequencies. Received: 21 July 1998 / Reviewed and accepted: 22 October 1998     

Material Model Research on Rubber Vibration Isolators

A viscohyperelastic constitutive model is proposed to describe the mechanical behaviour of vibration isolation rubber under broad-band vibration. This constitutive model comprises two parts： a component with three parameters to characterize the hyperelastic static properties of rubber materials, and the other component incorporating two relaxation time parameters, corresponding to high and low strain rates, respectively, to describe the dynamic response under vibration and impact loadings. Based on this proposed constitutive model, a series of experiments were performed on two types of rubber materials over a wide strain rate range. The results predicted from this model are in good agreement with the experimental data.     

A Kind of Backwards Thinking-fast Moving Consumer Goods (FMCG) Stock-controlling Analysis

To control the material purchase of a fast moving consumer goods (FMCG) enterprise warehouse and solve the problem of purchase planning,this paper formulates an integrated system of reverse logistics operated with a demand forecast model and an economic storage model.This is based on the supply chain and focused on the marketing terminal.By analyzing the integrated system reverse logistics and the timely information from the marketing terminal,the purpose is to effectively alleviate or solve the terminal stock-out which needs to replenish and oversupply which needs to return.According to the system,it can provide a theoretical basis for the enterprise inventory cost control.     

Development of typhoon driven wave nowcasting model in Southeast China Sea

Using Optimal Interpolation data assimilation of observed wave spectrum around Northeast coast of Taiwan Island, the typhoon driven wave nowcasting model in Southeast China Sea is setup. The SWAN model is used to calculate wave field and the input wind field is the QSCAT/NCEP data. The two-dimensional wavelet transform is applied to analyze the X-band radar image of nearshore wave field and it reveals that the observed wave spectrum has shoaling characteristics in frequency domain. The reverse calculation approach of wave spectrum in deep water is proposed and validated with experimental tests. The two-dimensional digital low-pass filter is used to obtain the initialization wave field. Wave data during Typhoon Sinlaku is used to calibrate the data assimilation parameters and test the reverse calculation approach. Data assimilation corrects significant wave height and low frequency spectra energy evidently at Beishuang station on Fujian Province coast, where the entire assimilation indexes are positive in verification moments. The nowcasting wave field shows that the present model can obtain more accurate wave predictions for coastal and ocean engineering in Southeast China Sea.     

A Novel Sliding Mode Variable Structure Controller Based on a Genetic Algorithm

A novel control method has been proposed by using the genetic algorithm （GA） for nonlinear and complex plants. The proposed control strategy is based on a variable structure control, it overcomes the defects of other adaptive methods such as strong dependence to the system. A GA is used to learn to optimally select integral coefficient C. Simulation results verified the effectiveness of the controller. For position control of Direct Current （DC） motor in practice, this method has good performance and strong robustness, and both dynamic and steady performances were improved.     

Hot-Dip Coating of Lead-free Aluminum on Steel Substrates with Ultrasonic Vibration

Hot-dip coating has been practically employed in manufacturing zinc alloy coated steel sheets.However,it is difficult to coat aluminum alloy on a bulky steel substrate without sufficient preheating,because a rapidly solidified layer containing gas babbles is formed on a substrate surface.A variety of iron-aluminides are also formed at the interface of a steel and aluminum hot-dip coating system,which is the main difficulty in joining of steel with aluminum.Ultrasonic vibration was applied to a steel substrate during hot-dip coating of aluminum alloy to control a rapidly solidified layer and a brittle reaction layer.Hot dipping of columnar steel substrates into molten aluminum alloy （Al-2.7 mass fraction Si-4.6 mass fraction Sn） was carried out through the use of a Langevin oscillator with resonant frequency of 19.5 kHz.The application of ultrasonic vibration is quite effective to control a rapidly solidified layer and a surface oxide layer from a substrate surface by the sonocapillary effect based on a cavitation phenomenon,so that the intimate contact is achieved at the beginning of hot-dip coating.The application of ultrasonic vibration to hot-dipping is effective to control a reaction layer with less than 5 #m in thickness.An impact test exhibits that the good adhesive strength is approved in hot-dipped aluminum coatings with a thin reaction layer of approximately 5μm.     

Blasting Technologies of Vibration damping in Subway Tunnel Passing under Upper Buildings Closely

Reduce the blasting vibration is important for blasting excavation in subway tunnel construction. Take the 3rd bid section of Line 3 of Qingdao subway project for example, the distance between tunnel vault and ground is 5~8m. In order to insure the safety of the upper buildings, technologies of parallel cut with large diameter empty hole, one-time initiation and delay by parts, and multiple shallow holes were adopted in the project. The results show that the maximum value of vertical vibration was limited in the criterion allowance, and the upper buildings was not damaged. Besides, problems that the number of nonel detonator is difficult to meet the requirements of excavating a large cross-section tunnel by blasting, multiple cross-section can’t be initiated simultaneously, and construction efficiency is low were solved, which ensure the construction safety and schedule.     

A VIBRATION RECOGNITION METHOD BASED ON DEEP LEARNING AND SIGNAL PROCESSING

Effective vibration recognition can improve the performance of vibration control and structural damage detection and is in high demand for signal processing and advanced classification.Signal-processing methods can extract the potent time-frequency-domain characteristics of signals;however,the performance of conventional characteristics-based classification needs to be improved.Widely used deep learning algorithms(e.g.,convolutional neural networks(CNNs))can conduct classification by extracting high-dimensional data features,with outstanding performance.Hence,combining the advantages of signal processing and deep-learning algorithms can significantly enhance vibration recognition performance.A novel vibration recognition method based on signal processing and deep neural networks is proposed herein.First,environmental vibration signals are collected;then,signal processing is conducted to obtain the coefficient matrices of the time-frequency-domain characteristics using three typical algorithms:the wavelet transform,Hilbert-Huang transform,and Mel frequency cepstral coefficient extraction method.Subsequently,CNNs,long short-term memory(LSTM)networks,and combined deep CNN-LSTM networks are trained for vibration recognition,according to the time-frequencydomain characteristics.Finally,the performance of the trained deep neural networks is evaluated and validated.The results confirm the effectiveness of the proposed vibration recognition method combining signal preprocessing and deep learning.     

Wavelet Transform and Neural Networks in Fault Diagnosis of a Motor Rotor

In the motor fault diagnosis technique,vibration and stator current frequency components of detection are two main means.This article will discuss the signal detection method based on vibration fault.Because the motor vibration signal is a non-stationary random signal,fault signals often contain a lot of time-varying,burst properties of ingredients.The traditional Fourier signal analysis can not effectively extract the motor fault characteristics,but are also likely to be rich in failure information but a weak signal as noise.Therefore,we introduce wavelet packet transforms to extract the fault characteristics of the signal information.Obtained was the result as the neural network input signal,using the L-M neural network optimization method for training,and then used the BP network for fault recognition.This paper uses Matlab software to simulate and confirmed the method of motor fault diagnosis validity and accuracy.     

主动控制中作动器非线性谐频的控制

采用主动隔振系统,能有效地控制低频线谱振动。在常规的作动器中,虽然可以有效地降低基频的振动;但二次谐波处产生的附加能量会影响隔振效果。通过理论分析与试验,研究了振动主动控制系统中电磁作动器的非线性现象,分析了进行低频线谱振动控制时电磁作动器在二次谐频处产生额外能量的原因,提出用谐波发生器自适应补偿作动器非线性现象的方法,结合前馈Fx LMS算法进行主动控制的试验表明,系统可得到较理想的控制效果。     

次级通道在线辨识的齿轮啮合振动主动控制

针对齿轮传动系统中由于啮合误差产生的周期性振动和噪声,构建在从动齿轮轴上附加压电作动器的齿轮主动结构,提出一种次级通道在线辨识的反馈FxLMS算法进行主动控制。应用C-MEX S函数在Simulink中编写了FxLMS算法模块和次级通道进行在线建模的自适应LMS算法模块,仿真算例验证了自建模块的正确性和算法的有效性。将控制算法代码下载到dSPACE中作为控制器,与内置压电作动器的齿轮主动结构组成硬件在环系统进行实验验证。结果表明,在不同啮合频率下,经过主动控制后的齿轮传动系统振动有了不同程度的减弱,在啮合频率基频处有6.9dB的衰减。     

混合隔振系统自适应模糊滑模控制

针对机械设备被动隔振在低频段隔振效果较差的问题,建立磁致伸缩作动器的电-磁-机转化数学模型,提出一种基于自适应模糊滑模控制算法,并用李雅普诺夫方法证明控制器的稳定性,将该控制策略与磁致伸缩作动器应用于混合隔振系统中。仿真结果表明：在单频、多频及随即激励条件下,自适应模糊滑模控制器具有良好的动态特性和鲁棒性,能够提高系统隔振效率并拓宽隔振频段,有效减小传至基础的力。     

抑制作动器间干扰的主动控制方法

通过优化作动器的控制目标，调整控制通道耦合方式，可有效抑制作动器间的正反馈，达到快速平稳收敛的控制目的。该方法基于滤波xLMS方法和多通道耦合控制模型，控制过程简洁、有效。实验结果表明，该方法能有效抑制多个作动器之间的互相干扰，而且较多通道分散控制具有更高的总体抑制性能。     

分散式自适应主动隔振控制算法研究

针对主动隔振中次级通道耦合会影响传统FXLMS算法稳定性问题,提出一种分散式解耦优化控制算法。主要是更新控制滤波器系数时忽略作动器与非临近传感器间的耦合,将多通道控制系统简化为多个并联的单通道控制系统,能降低算法运算量。但在一定程度上也会降低系统的收敛速度,为此,在辨识矩阵的估计模型中引入了作动器与非临近传感器之间的反馈补偿因子。仿真和试验结果表明,该算法可有效降低运算量,提高收敛速度和控制精度,双频线谱激励控制效果显著,振动衰减分别可达24.5 dB和12.4 dB。     

动力装置主动隔振系统硬件设计

随着人们对工作环境、设备可靠性及耐用度、加工精度和设备隐蔽性的要求不断提高,对于振动控制的需求越来越多。单纯的被动隔振系统无法抑制船舶电机频率1.414倍频以下的振动。主动隔振系统利用作动器产生与激振力相反的作用力可以有效地抑制低频振动。本文以船舶电机为控制对象,针对抑制200 Hz以下的低频振动开发了一套主动隔振系统。系统中采用加速度信号作为系统输入或反馈,以DSP+FPGA双核处理架构作为控制核心,最终以电磁作动器作为执行机构,通过实验验证,该系统可以达到预期隔振效果,抑制自身频率1.414倍频以下的振动。     

新型智能隔振复合结构的动态特性研究

针对精密机械的微位移隔振问题,设计了一种以PVDF压电薄膜为作动器和传感器的新型智能隔振复合结构。根据压电方程推导出了层叠式PVDF压电薄膜作动器厚度变形量表达式,建立了该智能复合结构的隔振理论模型,采用LMS自适应控制算法,以Matlab和有限元混合建模分析方式对本智能隔振复合结构的动态特性进行研究。有限元模型的分析结果与Matlab计算数据一致,验证了本新型智能隔振复合结构对微位移隔振的有效性,其结论将为精密仪器、微纳米设备的微位移智能主动隔振奠定理论基础。     

超磁致伸缩作动器用于振动主动控制中的仿真研究

目前对于太阳和地球引力变化引起的微振动，采用先进的主动控制能达到高精度的隔振要求。主要是推导并建立了超磁致伸缩作动器（GMA：Giant Magnetostriction Actuator）的动力学方程和数学模型，并将其运用到振动主动控制中，采用PID（Proportional-Integral-Differential）反馈控制方法，对双层隔振下层受到激扰的系统进行仿真计算，仿真结果表明它能对微幅低频振动衰减20-50dB，能起到明显的减振效果。     

超精密装置PID振动控制系统的仿真研究

 在仿生啄木鸟头部独特生物构造和隔振机理的基础上，采用主动隔振技术建立了超精密装置隔振系统结构及动力学模型． 结合超精密装置隔振系统的结构特点和性能要求，采用闭环PID主动控制系统，用Matlab软件进行了仿真分析．仿真分析结果表明，该振动控制系统宽频率范围内具有良好的减振效果，该系统可应用于超精密\测量、超精密制造设备的隔振领域．     

多点双层主被动一体化隔振器设计与仿真

为保证飞行器敏感仪器的精度,提出一种压电堆橡胶组合隔振器。对压电堆作动器和橡胶隔振器进行设计,提出一个多点支撑双层主被动一体化隔振系统,建立隔振系统的动力学模型,应用改进后的线性二次型（LQR）经典最优理论对双层隔振系统进行主动控制算法设计,并基于Simulink对正弦激励和随机激励情况分别进行了数值仿真分析。仿真结果表明,所设计的隔振器能够大幅度隔离源自基础的激励,证明所研究的隔振方法在理论上是有效的和可行的,从而为进一步的实验研究奠定基础。