Applied Mechanics and Materials Vols. 157-158

Abstract: This paper is based on analysis of mathematical model of the induction motor and the basis of the asynchronous motor vector control principle puts forward a torque of inner closed-loop speed, flux vector control system of induction motors. Using Matlab/Simulink construct simulation model and the simulation results are analyzed.

Abstract: From the perspective of knowledge retrieval and knowledge push, this paper introduces user preference based on the traditional search engines to meet the personalization demand of the domain knowledge of emergency. A retrieval system aiming at the emergency knowledge is designed by constructing the preference-based function module, setting the frame structure of user preference and improving the core operation process of the system.

Abstract: In order to obtain new ways of weak signal detection, we analyzed the motion states of nonlinear dynamic model Duffing oscillator in the case of different amplitude of input signals by solving the Duffing equation and expounded the basic principles of weak signal detection based on Duffing oscillator phase-change characteristics, further illustrated the relationship between signal detection accuracy and detection time by the experimental, researched the impact on signal detection coming from Gaussian white noise and also pointed out how to use intermittent chaos state to implement weak signal detection. The results showed that Duffing oscillator can be effectively detect the slight changes of input signal in the strong noises background, so as to achieve the purpose of weak signal detection. Compared with existing methods, it could greatly improve the detection results.

Abstract: During machining some ultra-intense and special-shaped parts, unstability and surface ablation often turn up. Some large and heavy parts are often machined with heavy duty NC machine tool. For avoiding the processing defects of the above parts, an online monitoring, diagnosis and control system is designed for heavy duty NC machine tool. The system can online monitor the operation condition of heavy duty NC machine tool and real-time control the processing. Some methods of signal analysis and processing are adopted such as spectrum analysis, wavelet analysis, Wigner-Ville distribution and Artificial Neural Network etc. The system is developed with C language and Qt based on Linux operation system. Optical fiber communication is adopted between industrial computer and NC system. Experiment platform of the system is machining an aircraft landing gear with five-axis NC machine tool. The scheme is verified feasible after preliminary test.

Abstract: This paper presents the heat transfer simulation of a new kind of rotary engine called Leaf Spring Rotary Engine. The structure and the principle of the prototype engine were introduced. The thermodynamic models including heat transfer model were presented. The contrast of the performance parameters between the heat transfer condition and the ideal condition was presented and the effect of the heat transfer to the performance of the engine was analyzed. It showed that the heat transfer loss would account for 24% of the input energy at the rated speed of 3000r/min. At the same time, the effect of ignition position to the performance of the engine was analyzed. The work would be used in the combustion system design and the performance optimization.

Abstract: Ferroresonance is a usual internal overvoltage in power system; it mostly occurs in distribution network that neutral hasn’t grounded directly, but it also happens in the high voltage grid that neutral-grounded system frequently. This paper introduced the fundamental theory of ferroresonance. An 110kV substation has been used as the model, to emulate the waveform of its ferroresonance, and also discussed the measure to remove the ferroresonance.

Abstract: Hydraulic electromagnetic energy-regenerative shock absorber is a new kind of shock absorbers, who can perform the function of a standard shock while acting as an additional source of power. One of the core components of this new shock absorber is the valve system. And its function is to rectify the direction of the oil flow. Then the oil can flow through the hydraulic motor from one port only no matter in expansion stroke or compression stroke. The research focused on the compactness, sensitivity and energy recovery rate of two different valve systems. And the results showed that the valve system composed of check valves better matched the hydraulic electromagnetic energy-regenerative shock absorber.

Abstract: In this research, multi-valued vowel systems are investigated to find optimal values for features like the advancement, height, and roundedness of vowels. For this purpose, two constraints are supposed to be satisfied: Values for the roundedness feature can discriminate, and the distance between an unrounded vowel and a corresponding rounded vowel may be small enough to show.

Abstract: Through the numerical calculation on elasto-hydrodynamic lubrication of grease lubricated ball bearing it’s obtained that: for the outer ring fixed, inner ring rotating with the shaft ball bearing type, as a result of the relative speed of steel ball-inner ring friction pairs is faster than the steel ball-outer ring, the film pressure peak and average film pressure on steel ball-inner ring friction pairs is greater than those of steel ball-outer ring, therefore, inner ring surface compared with outer ring is more likely to appearance wear and fatigue failure; In the process of steel ball rotation, there’s a rotation torque which caused by the asymmetry distribution of film pressure generated, and this rotation torque accelerates the rotation speed of steel ball.

Abstract: The coupling between vibration and centrifugal field is quite strong in multi-parameter combined environment test system. The motion part of vibration table deviates from its original operation position by the action of centrifugal force, which ends in the stuck of armature and causes damage to vibration table. In order to solve such problem, an air-push-type armature redress system with displacement feedback was proposed, which provided a recovering force to counteract the centrifugal force and pushed the motion component to its designed operation position. Some improvements were also made to enhance its reliability. The result of simulation and test about the armature redress system demonstrates that the system has an excellent performance and meets the requirement of counteracting the centrifugal force, which guarantees that the vibration table could work in centrifugal field and multi-parameter combined environment.