Abstract: Because neural network has the advantages of fast parallel processing, associative memory, self-organizing and self-learning, it is widely applied in the fault diagnosis of hydraulic system. Present in this paper is a fault diagnosis approch to a typical failure in hydraulic system which is leakage of hydraulic cylinder.The fault diagnosis approch is based on monitoring preesure singal,time domain feature and neural network. According to the method, the time domain feature is extracted from the pressure singal and costitutes the eigenvectors at first, then these eigenvectors are input into neural network to identify faults. The experimental results show that three modes of no leakage, slighter leakage and severe leakage are correctly identified and it can be used in the fault diagnosia of hydraulic syetem.
Abstract: Locating the causes of malfunctions in complex energy systems is an extremely difficult task, more than one fault mode may produce similar and possibly undistinguishable patterns of effects. This paper shows how fuzzy expert systems can exploit the available measurements from the data acquisition system to identify different component and sensor fault modes. Real sensor data (mass flow rates, pressures, temperatures, and key operating parameters) are compared with the expected values of the same quantities that are calculated using numerical models of local subsystems. The final objective is to verify the existence of some patterns of these attributes that univocally identify the considered fault modes. These patterns are then implemented as the set of rules forming the knowledge based on fuzzy expert system.
Abstract: For profoundly understanding the influence of wind speed on the dynamic tension of iced bundle conductor, the influence of wind speed on galloping rules, tension variation, and amplitude of quad-bundle conductor under number 4-8 wind were investigated by nonlinear finite element analysis and theoretical analysis methods. The results shows that wind speed have great influence on galloping amplitude and dynamic tension. Galloping amplitude will rapidly increase with the increase of the wind speed at the beginning, but when the wind speed increased to a certain extent, the increase of galloping amplitude in plane and dynamic tension will become not obviously, and the maximum dynamic tension approximately doubles the static tension. The galloping and tension variation rules of bundle conductor were changed from stability periodic motion to complicated quasi periodic motion.
Abstract: Numerical computation is processed for the analysis of large gap magnetic drive system driven by traveling wave magnetic field, and magnetic field analysis function of ANSYS software is used as the finite element analysis. Simulating is conducted to get the relationship between permanent magnet’s angular displacement and electrifying state of electromagnet coil. The rules of how main system parameter affect system’s driving characteristic are studied. The simulation is validated by experimental result: Torque capacity of the system can be improved by increasing the number of windings of coil, the electric current of coil, the outside diameter of permanent magnet, the magnetization of permanent magnet, or reducing the coupling distance between electromagnet and permanent magnet. Torque capacity of the system can also be improved by placing the position of electromagnet and permanent magnet in 5mm-10mm relative position in y direction (at both the left and right side).
Abstract: Automatic unloading valve is the critical pressure control element of emulsion pump station, the unloading pressure and the recovery pressure after unloading of the pump are two important technical parameters of the emulsion pump station. The working performance of the unloading valve can be improved by research and simulation of the two parameters, making clear the state of the unloading valve for emulsion pump station when working, calculating the electromagnetic thrust when the pilot valve and main valve core act as well as the response speed of the unloading pressure, checking and correcting the original spring force. The variation range of pump station pressure can be controlled within ±0.5MPa through the effective control on the unloading pressure and recovery pressure of the automatic unloading valve for emulsion pump station, which ensures the stability, reliability and sensitivity of the pump station when working. The improvement of the automatic unloading valve technology of internal unloading type is adaptable to the development needs of high-yield and high-efficiency modern mine for high pressure and super larger flow pump station.
Abstract: An excitation source for biomedical electrical impedance tomography system based on FPGA is designed and implemented with 33 KHz bandwidth and adjustable phases. Codes are programmed with PicoBlaze instructions by Notepad++, and compiled to user programs by KCPSM3 assembler. Digital-analog conversion is carried out in interruption subroutine, the output digital signals are sampled at the setting frequency and filtered by a second-order Butterworth low-pass filter. The proposed method offers a novel effective and feasible approach to satisfy the requirements of excitation source in bioelectrical impedance tomography system.
Abstract: To achieve the accurate and efficient NC milling simulation based on the discrete triangular mesh model, we proposed an algorithm for geometric modeling and intersection. We construct the R*-tree index for upper-surface nodes of mesh model, based on which the nodes within cutting region can be obtained. We compute tool path segments within cutting projection region of node, and calculate the minimum adjustment height of node according to tool path segments within cutting projection region and then change the z-value of node. Thus, we complete the intersection calculation in simulation process. It has been proved by examples that the algorithm for geometric modeling and intersection in NC milling simulation has strong adaptation to tool path segment type and that it can accurately and efficiently reflect the effect of NC simulation process based on the discrete triangular mesh model of rough.
Abstract: Function area layout of underground distribution center is an important part of urban underground distribution center planning so that it would indirectly affect the building and development of underground distribution center and even the whole urban underground logistics system. Based on Automod simulation platform, the function area layout planning method was built in order to avoid underground operation invalidation because of the illogical function area layout. First by analyzing relative operation of underground distribution center, multi-objective 0-1 mixed integer programming model of function area layout was built based on two indexes of relativity and transit cost among function areas. Then the heuristic algorithm or exact algorithm was used to solve the mathematical model mathematical model and find out the layout scheme after quantifying the indicators. Finally the final layout was gained by simulation and optimization of Automod simulation platform. There was an example for proving the feasibility of the method. The results showed that the method was available to analyze the function area layout impact and it was very important for decision-making of building the underground distribution center.
Abstract: A novel method was brought forward for the purpose of filtering Gaussian noise effectively by using variable step time matrix of the simplified pulse coupled neural network (PCNN). Firstly, the time matrix of PCNN, related to the grayscale and spatial information of an image, is calculated to identify the noise polluted pixels. Subsequently, a variable step, a long step for strong noise and a short step for weak noise, based on the time matrix is applied to modify the grayscale of noised pixels in a sliding window. And then wiener filter is used to the image to further filter the noise. Experiments show that the proposed filter can remove Gaussian noise effectively than other noise reduction methods such as median filter, mean filter, wiener filter etc, and the filtered image is smooth and the details and edges are sharp. Compared with existing PCNN based Gaussian noise filter, the proposed filter gets higher Peak Signal-to-Noise Ratio (PSNR) and better performance.
Abstract: In this paper, we report the condition to keep the optimal time-frequency resolution of the Gaussian window in the numerical implementation of the short-time Fourier transform. Because of truncation and discretization, the time-frequency resolution of the discrete Gaussian window is different from that of the proper Gaussian function. We compared the time-frequency resolution performance of the discrete Gaussian window and Hanning window based on that they have the same continuous-time domain standard deviation, and generalized the condition under which the time-frequency resolution of the Gaussian window will prevail over that of the Hanning window.