Papers by Author: Ying Xue Yao

Abstract: The energy issue has been the focus of world’s attention. Wind plays a crucial role in the development and application of new energy as a renewable and clean energy. Wind turbine is the core component of the wind power system. It usually can be divided into horizontal axis wind turbine (HAWT) and vertical axis wind turbine (VAWT) by the relative position of the spindle and the ground. This paper analyzes the advantages and disadvantages of VAWT and summarizes the improvement of the VAWT from the energy congregating technology and self-starting technology which can provide technical support for the research of VAWT in the future.

Abstract: This paper presents a simulation study of an H-type vertical axis wind turbine. Two dimensional CFD model using sliding mesh technique was generated to help understand aerodynamics performance of this wind turbine. The effect of the pith angle on H-type vertical axis wind turbine was studied based on the computational model. As a result, this wind turbine could get the maximum power coefficient when pitch angle adjusted to a suited angle, furthermore, the effects of pitch angle and azimuth angle on single blade were investigated. The results will provide theoretical supports on study of variable pitch of wind turbine.

Abstract: In order to enhance the efficiency of the Savonius rotor, this paper designs a new type of Savonius rotor with a rectifier. By using Computational Fluid Dynamics software to simulate and optimize the various parameters which affect the efficiency of the rotor. The sliding mesh method is applied here. The Cp-λ curves of wind turbine with different structural parameters are obtained after numerical simulation of flow field. On this basis, this paper gets the optimal structural parameters. And the results indicated that this new type of Savonius rotor has great improvement of efficiency compared with the traditional Savonius-type rotor.

Abstract: A viscometer based on velocity attenuation of rotating cylinder is presented in the paper. A solid rotor motor drives the cylinder immersed in liquid in a cup to a scheduled velocity. The electricity supply of the motor is cut, the velocity of the cylinder with rotor of the motor attenuates with time because of viscous torque and other resistance torque. The velocity is measured by optical encoder. Viscosity of the fluid was calculated by a computer. Experiments are carried out and results show that deviation of viscosity beyond 1000 mPa•s are below 3%. The viscometer can be used in measurement of viscosity beyond 1000 mPa•s in industry.

Abstract: A method for machining huge workpiece is proposed using coordinate transformation theory. The mathematical model of positioning is derived with nonlinear least square method and solved by iterative algorithm which is given by tangent plane iterative method. Then, initially generated tool paths are modified and optimized. The experiment demonstrates that this method for machining ultra-large-scale workpiece is feasible and correct. The proposed automatic positioning algorithm and tool path optimization method can be used to machine huge workpiece to improve accuracy and reduce cost.

Abstract: In this paper, a Colored Petri Net modeling method for early stage design of virtual assembly operation is presented. The characteristics of virtual assembly system, Petri Net and Colored Petri Net are analyzed. Some previous work in Petri Net application in assembly and virtual assembly system is discussed. The theoretical aspects of Colored Petri Net are introduced mathematically. Based on the mathematical presentation and the process of fasteners assembly operation, a Colored Petri Net model is constructed for the simulation of assembly operation in virtual environment. With CPN Tools software package, the simulation for evaluating the feasibility of modeling is implemented. It is demonstrated that the modeling approach can support the early stage design of virtual assembly system.

Abstract: An improved algorithm, dynamic collision detection with optimum discrete interval is presented to improve the efficiency of dynamic collision detection. The algorithm based on the minimum distance between two objects with relative movement to determine the next discrete position, on which collision or interference is free. The method using the minimum distance as discrete interval to determine the next interference-free position makes each interval longest under the constraint of safety so that the reliability between the moving object-pair is ensured while the efficiency is improved. The practical demonstration has proved that the improved algorithm is capable of high performance than that of the collision detection method with even discrete interval. This algorithm has been successfully used in a verification system of inspection process by secondary development of Pro/Engineer.

Abstract: To deal with the problems of complicated process, difficult operation and low efficiency for large-scale complex products assembly, a new immersive virtual environment (VE) with virtual reality (VR) technology is built in the process of assembly planning and training. The environment is composed of a free walk machine and spherical screen projection system. In this paper, a free walk machine with movement perception function is developed to achieve natural human-computer interaction. And an approach based on two viewpoints match is adopted to improve immersive effect of stereo projection in the projection system. On the basis of that, a geometry calibration method based on Bicubic NURBS(Non-Uniform Rational B-Spline) surface matching target-controlled dot-matrix is proposed to achieve non-distorted image on spherical screen. Finally, the environment is applied in the process of satellite assembly process planning, and the display result shows that the VE development is feasible and valuable.

Abstract: Value of viscosity of liquid at an arbitrary velocity is important in many manufacturing processes, method of rotation is used commonly to measure it at a scheduled velocity, but it is not convenient to measure it at an arbitrary velocity. A method based on cylinder rotation is presented in the paper and it is used to measure it at an arbitrary velocity. Derivation of mathematical models is executed and a simulation is carried in Matlab. Results show that the velocity of the cylinder in the liquid attenuates by exponential law and it is in accordance with mathematical models. Error analysis indicates that that the generation of them mainly results from unsuited velocity of cylinder, slippage between the cylinder and the liquid and misalignment between the cylinder and the cup.

Abstract: Virtual manufacturing technology has become an effective method for decision and planning in manufacturing. Due to ergonomics problems are widely concerned in assembly design planning, a human-centered virtual assembly system framework is proposed for ergonomics analysis for assembly operation in this paper. The six-layer framework integrates virtual human modeling, motion capture and recognition, ergonomics evaluation and virtual assembly process planning as an organic whole. Data exchanging and system function are discussed based on this framework. The work in virtual reality (VR) technology, motion capture technology, ergonomics method and optimization method for implementing the system is also described. The framework would provide a new approach for the combination of virtual manufacturing and ergonomics analysis in the future.