Applied Mechanics and Materials Vols. 130-134

Abstract: The phase errors of radar signals can be caused by random tropospheric refractivity fluctuations in a turbulent region, which affects the imaging performance of high resolution airborne SAR. A detailed simulation approach is presented to estimate the phase errors caused by atmospheric turbulence. Applying the von Karman spectrum as the model for turbulent refractivity fluctuations and the raw data collected by a Ku-band airborne spotlight-mode SAR with 0.1m resolution, we simulate the results of effects of atmospheric turbulence on SAR image focusing.

Abstract: Removed due to author's request.

Abstract: This paper developed a new design of variable swirl intake manifolds for four-valve DI diesel engine by setting swirl control valves in the intake manifolds. The 3-D numerical model under the same experimental condition was established and particular flow information in intake manifolds and cylinder was achieved. Influence of variable swirl intake manifolds on intake flow characteristics and in-cylinder swirl characteristics were analyzed. The simulation results show that the swirl intensity in cylinder can be tuned by this device. The swirl intensity increases gradually with decrease flow coefficient and it can meet the requirements of swirl intensity for different operating conditions.

Abstract: The aerodynamic analysis to human vocal folds owns great significance on understanding the principles of voice production,clinical disease diagnosis and treatment recommendations tovoice patients. This paper provides experimental data on airflow from a fourtimes scaled physical model.The results indicate that the pressure acting on the surface of the vocal cords is changed large partly by the glottal entrance angle and the glottic radius, andbringimportant impact on the glottic airflow field. The study has potential applications on voice rehabilitation, especially the design of glottis reconstruction programs.

Abstract: It is crucial measuring position and attitude of model to gain the precise and accurate data in wind tunnel tests. The model displacement videogrammetric measurement (MDVM) system and its key techniques such as the exterior orientation with big rotation angles and large-overlap, mark points, image processing and calibration based on the known distances are therefore presented. The practice example in Asia's largest (2.4m) transonic wind tunnel has demonstrated the MDVM system and its key techniques are correct and feasible, and they have application value.

Abstract: The application of a new microbridge mass airflow sensor is presented. Based on the introduction of the sensor’s I²C interface principle, TI’s ultralow power consumption MSP430F5438 micro controller is used as core processor to design a measurement system which has a good low power consumption character. The performances of the system are examined by the experiments. The result of the experiments can indicate that the relative error of the system is less than3.5%, and the sensor has the characteristics of high accuracy, low power consumption, fast response, strong anti-interference ability, etc.

Abstract: A maintenance interval optimization model for wind turbine gearbox considering the maximization component profit per unit time was presented in this paper. First, the principle and configuration of gearbox were introduced, and the failure characteristic is analyzed as well as the failure rate distribution of components in gearbox. Then, the concept of component income coefficient λ and element utilizing rate per unit time U(t) were given. λ describes the proportion that component takes up the total income of wind turbine electric power sale，and U(t) represents the average income per unit time to wind turbine electric power sale during 0~t. Based on above two concepts the model of optimizing maintenance interval was proposed. Last, the paper used the proposed method to evaluate wind turbine gearbox maintenance interval in an actual wind farm. The simulating results indicates that the component profits per unit time for gears, intermediate speed shaft bearings and high speed shaft bearings increases by 16.88%, 30.26% and 32.59% respectively.

Abstract: Stator winding inter turn short-circuit fault is one of the most common internal faults of fault-tolerant machine, which can disconnect the fault phases and keep operating correctly in the event of a failure. Stator winding short-circuit fault model is established through analysis. Based on finite element method, the high-power density fault-tolerant machine internal magnetic field simulation and analysis is implemented using Maxwell2D and induced voltage frequency spectrum is analyzed by FFT method. The characteristics of stator winding short-circuit faults are summarized, which lay a solid foundation for fault-tolerant machine earlier faults prediction and winding switching.

Abstract: As the main load-bearing component, the tower supports the weight as well as the wind force and the dynamic load in operation of the wind turbine. It also endures the blow of itself. The level of the tower design directly affects the performance of wind turbines. This paper discusses static characteristic and dynamic model anasysis of the tower of an 1.5MW horizontal axis wind turbine. It is also about choice and calculation method of finite element.

Abstract: In the past, when used the foundation coefficient to calculate the internal force of anti-slide pile, power series method is usually adopted. The deformation compatibility conditions and continuity conditions of sliding surface between non-anchoring section and anchoring section are exploited to determine the final result, causing the lengthy solution process and that there is no guarantee for the calculation accuracy. This paper uses the foundation coefficient method in the calculation of internal force of anti-slide pile and employs the “m-k” method with a more complicated up-down foundation structure to get the finite difference equation to determine the new-type deeply buried anti-slide pile displacement and internal force. Then the calculation on the internal force and displacement of the whole pile can be realized easily through the procedure method. Finally, this paper makes a contrastive analysis on the result of the finite difference method and finite element calculation through the case study. As long as the equal differential step length is small enough, the calculation accuracy can meet the demand of engineer design and the program graph processing result can optimize the design of anti-slide pile.