Papers by Author: Yun De Shen

Abstract: With the heightened concern for renewable energy because of significant energy problems, the interest on wind energy has been greatly increased. In this study, 4 kinds of RANS turbulence models were compared and discussed based on developed analysis model. At first, a numerical model for 1kW wind turbine blade was constructed. In the following step, Spalart-Allmaras, standard k-ε, RNG k-ε and Reynolds Stress turbulence models were candidated for comparison. The analysis results show that standard k-ε or RNG k-ε model is relatively good selection under the condition of considering accuracy and computational effort simultaneously. The developed analysis model and simulation results have made a theoretical basis for improving the simulation accuracy of wind turbine blade with minimum computational effort.

Abstract: To meet the needs of test for compound oscillatory roller transmission (CORT) reducer, A comprehensive test system for precision transmission performance was designed, the test-bed structure and control principal of which were introduced. First, a transmission performance test method was proposed and focused on the transmission performance of velocity ratio, accuracy, and efficiency. Then, user interface based on LabVIEW program was designed, and the transmission performance of torque, angle, velocity, velocity ratio, return difference, efficiency could be displayed. Finally, measurement example on an E80 type CORT reducer has been made, and shows that the proposed test system is suitable for test for these reducers of high-precision drive, high stiffness, high load characteristics.

Abstract: In this paper, the visual tracking algorithm for a moving target is proposed for the biped robot of which camera movement is irregular. Hexagonal Matching Algorithm is used to measure the changes of size, location, and rotation angle for a moving object from its image frame. For enhancing the efficiency of the tracking, we can adaptively adjust the starting point and the size of search area from the image information obtained. Finally, by using Affine Transform and Kalman Filter, the position estimation of the moving target is refined against the swing of the camera. Experiments with 20-DOF biped robot using mono vision sensor are implemented to prove the reliability of the proposed method.

Abstract: Thermoforming is one of the most versatile and economical processes available for shaping polymer products. The heating time and heater power must be optimized for obtaining good products efficiently. In this study, the method for calculating the required heat flux was researched at first. In the following step, the analytic solution was studied for getting optimal heating time and heater power. Finally, the relationship between heater power and heating time was discussed. The developed method in this study will be widely used to shorten the cycle time under the condition of satisfying requirements of thermoforming.

Abstract: Obtaining a uniform thickness of the final product using thermoforming is difficult, and the thickness distribution depends strongly on the distribution of the sheet temperature. In this paper, the time-dependent temperature distribution of the total sheets in the stage of storing was studied using the analysis code which has been verified based on the experimental data. It was found out that the time for storing should be managed for decreasing the temperature difference between the sheets. The time-dependent temperature distribution of the total sheets and the method for analysis in this study will be used to improve the quality of the final products.

Abstract: The output power efficiency of the fuel cell system depends on the anode pressure, cathode pressure, temperature, demanded current, air and hydrogen humidity. Thus, it is necessary to determine the optimal operation condition for maximum power efficiency. In this paper, we developed a dynamic model of fuel cell system which contains mass flow model, membrane hydration and electro-chemistry model. Experiments have been performed to evaluate the dynamical Polymer Electrolyte Membrane Fuel Cell (PEMFC) stack model. In order to determine the maximum output power and minimum use of hydrogen in a certain condition, response surface methodology optimization based on the proposed PEMFC stack model is presented. The results provide an effective method to optimize the operation condition under varied situations.

Abstract: Based on the Matlab/Simulink module modeling for Fuel Cell Hybrid Electric Vehicle was carried out, which is comprised of the fuel cell stack model, a DC/DC converter model, a battery model, a motor model, avehiclemodel and a driver model, and Hybrid Control Unit(HCU) was developed. The HCU control strategy also incorporates regenerative braking and recharge for battery capacity recovery. Vehicle speed effect is evaluated in New Europe Driving Cycle. The simulation result that the control strategy implemented by HCU is achievable, and which proves that the mode of Start, Accele_FCBat, Cruise, RE_Brake, Power_FC and Pause operate sequently as well as reliably.

Abstract: This paper describes vibration suppression of the flexible cantilever beams using shunted electromagnetic transducer. The proposed system consists of a coil attached on a cantilever and a permanent magnet placed under the bottom of the coil, and both ends of the coil were connected to the parallel resonant RLC shunt circuit. The dynamic model of cantilever beam with shunted electromagnetic damper was theoretically formulated and used to compare the analytic predictions with the experimental results. The vibration and damping characteristics of the flexible beams with the electromagnetic shunt damper were investigated by tuning the circuit parameters. Also, the effect of the magnetic intensity on the shunt damping was studied with the variation of the gap between the aluminum beam and the permanent magnet. Presented results show that the electromagnet shunt damper has good vibration reduction effect, and it can be successfully applied to reduce the vibration of the flexible structures.