Advanced Materials Research Vols. 490-495

Abstract: The main purpose of this paper is to propose an improved empirical mode decomposition (EMD) approach based on principal component analysis (PCA). EMD is a time-frequency analytical method used to deal with non-linear and non-stable signals. But it generally fails to separate IMFs from primordial signal consisting of several adjacent frequencies,especially when noise is strong.In this papar the PCA is introduced to solve this problem.First,PCA is used to pro-process sample signal to get principal components. Then several signals are reconstructed by principal components.Reconstructing signals can separate adjacent frequencies and depress noise.With the EMD method again,right characteristic information is obtained from intrinsic mode functions (IMFs). Simulated signal is analyzed by the proposed method, as shown by example. Compared to the EMD method, this improved method is proved to be superior to the traditional EMD method in extracting the characteristics of signal,which consisting adjacent frequencies and interfered by strong noise.

Abstract: In this paper, a velocity servo-based hybrid position/force control scheme for a grinding robot is presented. It simultaneously performs stable force control and exact position control along curved surface for a grinding robot. The force feedback loop changing the force to velocity, which will be used in the velocity servo-based robot, can control the force directly and has a faster response. The position feedback loop controls the grinding tool in a desired trajectory in Cartesian space. An overview of the control algorithm as well as the force data signal processing and the communication between force sensor and robot controller is described.

Abstract: This paper introduces a new type of automatic steel bundling machine for bundling process, which includes a pneumatic action process, mainly do some researches on the pneumatic control system. The system chooses PLC as the core control component, puts forward the hardware of control system and control flow. Eventually we have been designed the control program.

Abstract: A Multi-electrode Capacitance Sensor for measuring containing water ratio in crude oil and its circuit has been designed. The multi-electrode capacitance sensor is assembled with the structure of combining, which is easy to clean and maintain. By setting up the mathematic model of the measuring method, the function of the changing rate of containing water ratio in crude oil and the equivalent capacitance of multi-electrode capacitance sensor is achieved. A experiment to contrast the measuring containing water ratio in crude oil with pent-electrode capacitance sensor and mono-electrode capacitance sensor has been carried out, proved that comparing with the result of experiment ,the precisions of fifth-electrode capacitance sensor in measuring the containing water ratio in crude oil has been greatly improved. Furthermore whether the containing water ratio in crude oil is high or low, the measuring result by using fifth-electrode capacitance sensor is stable.

Abstract: One-dimensional Gaussion rough surface is simulated and employed by Monte Carlo Method, the composite backscattering from one-dimensional Gaussion rough surface with rectangular cross-section column above it is studied using Method of Moment. The curves of composite backscattering coefficient with scattering angle and frequency of incident wave are simulated by numerical calculation, the influence of the root mean square and the correlation length of rough surface fluctuation, the height between the center of the rectangular cross-section column and the rough surface, the length and the width of the rectangular cross-section column is discussed. The characteristic of the composite back-scatting from one-dimensional Gaussion rough surface with a rectangular cross-section column above it is obtained. The results show that the influences of the root mean square and the correlation length of rough surface fluctuation, the height between the center of the rectangular cross-section column and the rough surface, the width of the rectangular cross-section column on the composite backscattering coefficients are obvious while the influences of the length of the rectangular cross-section column on the complex backscattering coefficient is less.

Abstract: A key issue in NCS is network transmission. In the research of network control, in some special fields, the system performance could be evaluated based on the real-time character of data transmission in the LAN, but the result gotten in this kind of method isn’t representative. In this paper, a simulation model is firstly established via the NS-2 software under research of network transmission, and then the interval segmentation time-delay and the constant time-delay compensation methods of network control are investigated under this environment. Simulation result validates the effectiveness of the model.

Abstract: This paper is a research about the speed adjustment of Parallel Hybrid Electric Vehicle engine under different operating conditions. It seems that the traditional PID controller is powerless owing to nonlinear and time-varying of the engine system. This paper studies coordinated control problems of the engine by using compound fuzzy-PID control method, which greatly reduces the difficulty of the nonlinear system control and improves robustness and real-time of the control system. And dynamic model of PHEV engine is established by using kinetic equations in this paper. Compared with traditional PID and fuzzy system, it proves that compound fuzzy-PID system has a better control performance, which can meet the requirements of quick start of the engine and speed regulation under the three kinds of adjustments of engine idle speed, vehicle acceleration and speed regulation in the process of the drive mode switching.

Abstract: The transfer matrix of rolling bearing including squeeze film damper (SFD) is studied, and the rotor – bearing system is modeled by transfer matrix method of multi-body system. It is proved by an example that the method, which provides a new idea to solve the problem of complex rotor – bearing system, is feasible and effective.

Abstract: In the practical need in order to make the most effective image compression in this paper, a new image compression used wavelet neural network model, and gives the corresponding calculation formula and algorithm procedures, By using wavelet transform good time-frequency local area on the characteristics and neural network self-learning function characteristics, overcome traditional BP neural network of hidden-layer points are difficult to be determined and the convergence speed is slow and easy to converge to a local minimum points shortcomings. The results of the simulation experiment prove wavelet neural network image compression characteristic and the convergence speed are much better than traditional BP neural network, and show that the algorithm is effective and feasible.

Abstract: Hidden Markov model (HMM) for the diagnosis of incipient faults in analog circuits is presented. Firstly, output voltage signals under faulty conditions are obtained with simulation. Subsequently, output voltages corresponding to the test frequencies are extracted from the response of analog circuits. Finally, the output voltage vectors are used to form the observation sequences, which are sent to training HMM to accomplish the diagnosis of the incipient faults. The performance of the proposed method is tested, and it indicates that the method is effective and has better recognition capability than the popularly used back-propagation (BP) network.