Applied Mechanics and Materials Vols. 128-129

Abstract: The failure data of crank rod system was analyzed by using weibull parallel model on the base of the simple weibull method. The distribution parameters of the weibull parallel model were estimated by using drawing method. The solving process of WPP drawing method was given in detial. Results show that the fitting degree of the failure data in the weibull parallel model is higher than that of the simple weibull distribution model, and it can more accurately described the failure distribution curve of the system in life cycle, which can provide necessary information for engine reliability indexes computation.

Abstract: The mechanism with clearance is a nonlinear system, then using classical control theory and modern control theory cannot obtain satisfactory control effect. Therefore，In order to control the nonlinear error cause by clearance, the conventional fuzzy control and parameter self-regulation fuzzy control are considered by using the fuzzy control’s humanization and intelligent. The results of test show that: the nonlinear error got smaller and the stability of system got obvious improvement as the introduction of intelligent control system.

Abstract: A heavy special vehicle is used in a steel mill. The failure and repair records of the vehicle are available. The study aims to identify main failure modes and areas needing improvement in the working device of the vehicle. The reliability bottlenecks are identified through analyzing the repair reports and the countermeasures for reliability improvement are suggested based on the analysis results. The approach presented in this paper is useful for periodically reviewing and continuously improving the reliability of complex repairable systems.

Abstract: This paper proposed a technology of fault diagnosis for CNC machine based on hybrid neural network. Before the fault diagnosis was made, the fault patterns were firstly obtained from technical manuals and field experience to build a sample set, and then they were classified and coded according to the rule. In order to improve diagnosis speed, the fault diagnosis system was designed as a hybrid neural network system which consists of two-grade neural networks. When the fault pattern was input the system, the fault was first classified by the first-grade BP network, and according to the fault type, the corresponding second-grade ART network was activated to perform fault diagnosis. In this paper, the train algorithms of two kinds of neural networks were programmed by MATLAB. Comparing with the traditional diagnosis method, the presented technology possesses advantages of automatic fault diagnosis and ability for self-learning and self-organization.

Abstract: The proposed method in this paper indicates two issues, selection of discriminative features and classifies event classes with minimum error. Wavelets features (WF) of power quality (PQ) events are extracted using wavelet transform (WT) and fuzzy classifiers classify events using these features. The captured signals are often corrupted by noise; the non-linear and non-stationary behaviors of PQ events make the detection and classification tasks more cumbersome. Performance comparison of the proposed method is made with three other fuzzy classifiers using different wavelets and superiority is verified. In the proposed approach of event classification, fuzzy product aggregation reasoning rule based method has been used.

Abstract: In this letter, we propose a novel scheme to reduce the PAPR of OFDM signals. It combined the channel estimation in OFDM system based on comb-type pilots and Flipping PTS algorithm. At the sender we insert comb pilot independently and evenly into every partitioned sub-blocks after partition. The side information of Flipping PTS algorithm as one part of the channel frequency response is transmitted. We can achieve Flipping PTS algorithm without SI. Simulation results show that performance of the new algorithm without SI is worse than the algorithm with SI. However, it reduced PAPR, increased of the data rate.

Abstract: Digital down converter (DDC) is based on the theory of Software Defined Radio (SDR) and multirate signal processing, extensively applied in digital receivers of communications systems. An improved resource-efficient DDC with polyphase architecture and distributed arithmetic (DA) is presented in this paper. The design based on Xilinx FPGA Virtex-5 has more flexible characters and higher precision computation with less resource consumption.

Abstract: Hydrolysis process is the key part of sulfuric acid method’s production technology of titanium dioxide, it is also the most rigorous part of the process control, and precipitate out the white hydration precipitation TiO2 from the mother liquor, and separate from other soluble metal sundry ions, further purify the TiO2. The quality of hydrolysis product not only affects the normal operation of the follow-up, but also affects the quality of the final product directly. This article do some study and design to the hydrolysis automatic control, use computer，DCS and PLC control the hydrolysis operation process, temperature control, steam heating system, That means comprised monitoring station by the DCS，CRT, mouse and keyboard replace the simulates panel and operator, and use the fuzzy theory control the hydrolysis temperature rise process, improve the accuracy and precision of the operating, at the same time, reduce the labor intensity of the workers, realize the automatic control of the hydrolysis process, stabilize and improve the product quality effectively

Abstract: Small cylindrical object navigating near free-surface is subject to wave disturbance. Wave disturbance can dramatically influence the depth control of the near-surface navigating object. A self-regulating fuzzy depth control method is proposed to keep the small cylindrical object navigate at the expected depth under free-surface disturbance. The near-surface dynamic model of the cylindrical object is presented and the fuzzy depth control method is modeled. The results obtained by a series of hardware-in-loop simulations demonstrate that the self-tuning fuzzy depth control method is valid to keep the small cylindrical object navigate steadily in the expected depth under free-surface disturbances.

Abstract: To improve the control precision of six degree-of-freedom parallel platform, a fuzzy immune PID control method was presented based on the immune feedback mechanism and fuzzy control theory, and the parameters of PID controller was optimized with hybrid algorithm. First, least square algorithm was used for off-line optimization to form immune feedback control system. Then, genetic algorithm was used for on-line optimization to get the optimal performance parameters of immune PID control system and the optimal fuzzy proportional parameters. Simulation results demonstrated that the control method designed gets tracking effect with high precision and speed.