Advanced Materials Research Vols. 712-715

Abstract: The development of signal processing technology not only improves the reliability of qualitative and quantitative ultrasound detection, but also promotes the sensitivity and precision. This paper introduces the new progress of signal processing technology in application of Ultrasonic Nondestructive Testing, including the basic principle, characteristic and localization of Wavelet Transform, Adaptive Filter Technique, Artificial Neural Network and Support Vector Machine application in Ultrasonic Testing, and the trend of development in the future.

Abstract: For safety-designing an equipment/system in civil aircraft, ARP4761 & SAE ARP 4754 is important common standard. But in these standards there has no clear description aircraft structures effect on the equipment/system. In this present paper, aircraft structures effect on design an equipment/system is considered by methods of FHA-FMEA-FTA-SSA quantitatively by conservative assumption. A flow chart of requirement considering structure-support effect is developed.

Abstract: In this paper, we consider a constant-stress accelerated life test with competing risks for failure from exponential distribution under progressive type-II hybrid censoring. We derive the maximum likelihood estimator and Bayes estimator of the parameter and prove their equivalence under certain circumstances. Further study of the estimators indicates that missing of failure modes would result in overestimation of the mean lifetime. Finally, a Monte-Carlo simulation is performed to demonstrate the accuracy and effectiveness of the estimators.

Abstract: The performance of hydraulic pump will directly affect the normal work of the entire hydraulic system, so it is essential for its condition monitoring and fault prediction. It collects vibration signal and pressure signal for hydraulic pump which degenerates from the normal state to loose slipper state. It uses wavelet packet to decompose energy of frequency area in order to get fault feature vectors and builds support vector machine prediction model for feature vectors, then predicts possible fault by D-S evidence theory. The experiment results show that the method can effectively predict fault for hydraulic pump.

Abstract: With the extensive use of infrared imaging reconnaissance equipment on the battlefield, recently how to simulate the reconnaissance effect of infrared imaging equipment has become a key issue that urgently needs to be solved in warfare simulation. To solve this problem, a method of reconnaissance effect simulation for infrared imaging equipment under warfare simulation is presented in this paper, which divides the entire reconnaissance process into a series of phases of the search, detection and recognition, confirmation and positioning. For the needs of a higher degree of confidence without too many complex calculations and parameter input, the established model is mainly dependent on the equipment tactical and technical performance indicators. Comparing the calculation results with the experimental data shows that the calculation error is smaller and this method presented has a good prospect in the warfare simulation.

Abstract: A method based on modal analysis is put forward to solve the problem of detecting the debond defects of solid rocket motor nozzle divergent section in service. The modal flexibility curvature difference is used to identify the debond defects. The locations and sizes of debond defects can be estimated accurately. The results of simulations indicate that the inspection speed and efficiency are much higher than those of ultrasonic method are. The method is easy to realize outfield detection. This method can be applied to identify the debond defects of the nozzle divergent section or multilayer composite structure. It provides theoretical guidance and methodological reference for debond defects detection of multilayer composite structure.

Abstract: The vibration of windings and iron core causes the overall vibration of the transformer. Significant changes of transformer vibration condition will take place when the windings or core has fault, so the vibration method can be used to diagnose the transformer's potential fault. The characteristics and transmission route of the transformers' vibration were analyzed. The vibration of a certain transformer in converter station was picked up, using vibration measuring system. The test results aree analyzed comparatively and maintenance suggestion was proposed.

Abstract: According to the electric vehicle driven by dual wheel hub motors, the article analysed the principle of mechanical differential. And the article used the principle of differential under the same force of mechanical differential, put forward a new adaptive control strategy of electronic differential based on torque control. According to torque control£¬the controller controls the speed of the drive motors on both sides, which achieves the aim of the adaptive electronic differential.

Abstract: A new digital DC servo driver based on DSP and FPGA for planar motor was designed in this paper. Current feedback and digital self-tuning PID algorithm control strategy are applied. Switching power amplifier or class D amplifier is the choice of power amplifier. The most prominent characteristic of the servo driver used in planar motor is high efficiency, low temperature drift, small size, fast response, and high-bandwidth. Finally, the performance parameters and power loss parameters of the servo driver are given.

Abstract: In order to realize the high precision tracking control of the vehicular eletro-optical tracking turntable with the car bodys vibration, it is necessary to design a high performance turntable servo system and a set of high precision eletro-optical tracking control scheme. In this paper, a digital servo system is designed, which has the control platform based on PC104 processor, has the torque motor as the actuator, has the gyro as the inertial velocity measurement tool and has the high precision encoder as the position measurement tool. Then, the gyrostabilized double speed loop control algorithm with disturbance observer compensating is designed to realize a good inertial velocity stability performace; and, a set of eletro-optical tracking compound position loop control scheme based on the target-missing quality data processing, the segmented PID control and the acceleration lag compensating control is proposed to enhance the eletro-optical tracking precision. The result shows that the tracking turntable based on the control technology designed in this paper is reliable, responses quickly, has a good speed stability performance and a high eletro-optical tracking precision performance.