Advanced Materials Research Vols. 631-632

Abstract: When the intermediate cuttings cut the wood, the efficiency of the vibration of the circular saw web was low so that the saw web always broke off. Moreover, the high-speed rotation would cause the vibration of the complete machine and result in the initial failure of the machine. Therefore, seeing from the problems from the analysis above and practice, the new design of the current micro intermediate cuttings seemed especially important. In the thesis, the author made a new arrangement of the micro intermediate cuttings of machinery tools, carrying out three-dimensional modeling and simulation of the complete machine and made an analysis of the dynamic cutting process by means of analyzing the working condition of circular saw web.

Abstract: In order to improve discharge characteristics of engine ignition, a dual-coil ignition was designed. Simulation models of ignition energy, secondary voltage and spark duration of this ignition were established. The influence of discharge time interval and energy distribution method on discharge characteristics of the dual-coil ignition was studied. Compared with single-coil ignition, the results show that dual-coil ignition produced higher secondary voltage, ignition energy and extended spark duration. When total ignition energy remains constant, the dual-coil coupled discharge mode can improve energy conversion efficiency. The ignition can achieve flexible switching of discharge modes and optimal control of discharge characteristics，which is beneficial for improving fuel economy and reducing exhaust emissions.

Abstract: Lacking of failure samples, the estimation of MTBF of special equipments is imprecise. Half of the MTBF is regarded as inspection period in classical condition-based maintenance analysis. Because of ignoring reliability life changing of the product, maintenance with fixed period usually leads to more or less of inspection and replacement. According to factory and laboratory failure data, reliability estimation modal of small samples is built for crane based on Bayes theorem, and reliability forecast of the girder of crane is realized. Further more; for special equipments with potential failure mode, first inspection period model of condition-based maintenance analysis based on RCM is set up, on the basis of maintenance cost and availability strategy, the calculation methods of optimal inspection periods are given. This research provides a reference for safety evaluation and inspection strategy establishing for condition-based maintenance of mechanical-electrical special equipments which lack failure data of factory and laboratory.

Abstract: The paper is examined to establish the optimal set of control parameters for the design of a 3MW direct-drive permanent magnet synchronous generator by applying the Taguchi method. Taguchi orthogonal array is employed to determine the optimal combination of design parameters, including: steel lamination material, applied voltage, slot number, diameter of air-gap, magnet pole materials, magnet pole depth, stator outer/inner diameter, and length of stator core under the rated rotating speeds of the generator. Next, core loss database of used electrical steel laminations in generator was investigated. Effect of these control parameters of the permanent-magnet synchronous generator on the output power and efficiency are also analyzed in the paper. Results show that the designed 3MW direct-drive permanent magnet synchronous generator is capable of operating stably and assure the adequate 3MW power output and good efficiency greater than 95%.

Abstract: With the advance of electronic technology,the filed-oriented control of voltage space vector PWM have become more efficient in generator side converter control.This paper presented the direct driven wind turbine model and the permanent magnet synchronous generator (PMSG) model in synchronous rotating d-q reference frame.Using filed-oriented control of voltage space vector PWM in generator side converter control for enhance efficiency. The optimal control strategy can keep wind turbine working at optimal tip speed ratio for capture maximum wind power.A novel nonlinear PI controller for anti-windup implemented in control loop for highest efficiency of wind turbine which can be reached.Simulation results verified and shown via Matlab/Simulink that the performance of nonlinear PI controller for anti-windup in generator side converter control system is better than traditional PI controller in control loop for wind turbines.

Abstract: This work presents a approach for multiple cooperating mobile robots for moving object tracking in unknown environment. Each robot in the team uses the full covariance extend Kalman filter based algorithm to simultaneously localize the robot and target while building a landmark feature map of the surrounding environment. Meanwhile, in local robot system the covariance intersection based data fusion method is used to fuse information sent by the other robot teammates, those information may contains the location of target and the location of robot itself from other teammate’s point of view. The method is distributed, and let the multi-robot system have the ability of robustness. The results of simulation validate a higher accuracy of our method compared with non-fusion single robot solution.

Abstract: In the tyred machinery chassis dynamometer control system, a fuzzy PID controller was used to adjust the exciting current of a DC dynamometer in order to change the resistance load torque, so the requirement of roller load for simulating the run resistance from the road surface was satisfied. A fuzzy PID arithmetic was designed to control the resistance loads, the system performance was improved by simulation. The software of the detection line measure-control system was designed in VB, the technical parameters of the machinery chassis could the automatically detected.

Abstract: For building discontinuous dynamic scanning of film thickness of lithium battery systems, dynamic scanning of laser sensors is realized based on threshold judgment and multi-resolution wavelet algorithm for dynamic noise reduction. Through the analysis of scanning the system inherent frequency, vibration frequency and threshold in various scanning mode measurement results, indicate that upper and lower threshold in 160-210 ms can reach better accuracy. The results show that dynamic scanning detection accuracy (MSE) reaches 2-3μm, compared with the traditional time domain, frequency domain and unique multi-scale wavelet de-noising, the method applies to different lengths and discontinuous of coating thickness measurement.

Abstract: In order to improve the thermal stability of silicon micro hotplate, a ceramic hotplate with structure of suspending bridge was designed. The steady-state thermal response of the hotplate and the structure of the micro-heater were simulated by using the finite element method. By using conventional microelectronics technology and laser micro processing technology, the microstructures with thickness of 100 μm and bridge width of 2 mm were produced. The test results show that the ceramic hotplate has higher working temperature than traditional silicon hotplate, and it can be worked steadily at the average temperature of 630 °C on 1.5W heating power. Taking ceramic hotplate as heating platform and nano-SnO2 materials with Pd doping concentration of 0.2 at.% and 10 at.% as sensitive materials respectively, the array with two gas sensors was designed and fabricated. The gas sensor array can be used to detect single gas of CO or CH4 with high sensitivity and good selectivity when it works with constant heating voltage. When the sensor array works with periodic voltage heating pulse, it can realize quantitative detection for mixed gases of CO and CH4.

Abstract: Electric vehicles with four in-wheel motors have its inherent advantage to recover energy because all of its four in-wheel motors can generate electricity energy when braking. For the purpose of study the property of regenerative braking of four-wheel-drive electric vehicles, three traditional distribution strategies of traditional vehicles are adjusted based on the property of in-wheel-motor. A simulation model is established by using Matlab/Simulink and CarSim software, and the simulation is made based on UDDS and 1015 driving cycles. The simulation result shows that, the parallel distribution strategy has the highest regenerative efficiency and regenerative efficiencies of fixed proportion distribution strategy and ideal distribution strategy are almost the same.