Advanced Materials Research Vols. 718-720

Abstract: According to the characteristics of large angle of pendulum movement, in order to ensure the stability of the fixed plate motion pendulum, to analysis quantitatively the relation of oscillation angle and plate movement, it designed an automatic flat control system with STC89C52RC as the core of control chip, collected the information of oscillation angle by the sensor of angle,controls the angle of surface plate by advanced four phase stepper motor,uses the improved BP neural network to real-time correction in the software design part, the control system has high control precision, the stability and speedability of control system of surface plate were improved by measuring .

Abstract: In this paper, the research object is composite-cycle air-cooling system. First,gave a brief introduction of the system structure and the working principle in power plant. Then the optimal vacuum calculation model was established with the analysis of performance indicators and the amount of equipment production, consumption power of system. Analyze the impact of the ambient temperature to system optimal vacuum in variable conditions. Lastly, combining the climatic conditions of example, which can be drawn is that when the annual best vacuum is 4.8kPa, the running annual earnings is the highest. This article provides guiding significance for correct understanding and engineering applications of composite-cycle air-cooling systems, also further confirm the feasibility of composite-cycle air-cooling system.

Abstract: In order to calibrate the response characteristic of voltage dividers, the article presents a potable high-voltage nanosecond rectangular pulse generator based on the transmission-line theory. The generator consists of DC high-voltage source, pulse forming line (PFL), special high-voltage switch, pulse transmission line (PTL), resistive load and coaxial voltage divider. The compact charging and discharging circuit is developed coaxially and the interference proof performance is excellent. The voltage amplitude and the pulse width can vary from the output of the DC high-voltage source and the length of PFL respectively. In the article the theory of pulse forming process, the design and the key devices of the generator are investigated theoretically and experimentally. The experimental results demonstrate that the generator can meet the measurement demands and export well-defined rectangular pulses with the rise time less than 751.738ps and the voltage amplitude up to 2kV.

Abstract: Natural conditions have very important influence on the performance of the wind power generation system, especially high temperature environment will lead to device life reduction, and have a strong impact on wind power system reliability and life. The small wind power system main circuit loss is estimated and the model of which is built by ANSYS 12.1 experimental tools, the more accurate the main circuit of temperature field distribution are simulated by the mapping method, mesh discretization model, as well as some certain basis are provided for other parts of the simulation, so as to the circuit structure is better optimized and improved, and the small wind power system stability and reliability are enhanced.

Abstract: This paper presents the speed control of brushless dc motor drive employing sliding mode control. In order to improve the dynamic performance of the speed control of a Brushless DC Motor (BLDCM), a strategy of sliding mode control with Feed-forward Exponential Reaching Law, compared with the traditional PID control under Motor mathematical model given, the control performance was improved greatly. The simulation results showed that the control strategy has good performance with fast response, no over-shoot, and improved the robustness of Brushless DC Motor.

Abstract: This paper focuses on the effectsof the high order term in Duffing equation. Firstly the averaging equation andthe bifurcation equation are deduced through the multiple scale method.Secondly, the transition sets and several different bifurcation diagrams areobtained based on the singularity theory. The result shows that the high order term induces richer bifurcationcharacteristics.

Abstract: As the indoor environment is complex,the attenuation model is imprecise.and the wireless location system is inaccurate.It is a effective method calculating attenuation factor with different distance RSSI data and selecting proper reference distance for solving single reference distance defect. The experiment verified that it can modify distance measurement mode and improve the accuracy and reliability of indoor distance measurement based on RFID.

Abstract: A 10-bit successive approximation (SAR) analog-to-digital converter (ADC) in 90nm CMOS dedicated for sample rate limited applications is presented. The SAR ADC achieves an extra low energy by applying only one pre-opamp and without any low voltage techs in preserving the desired low power. HSPICE simulation results show that at a supply voltage of 1V and an output rate of 2.52kS/s, the SAR ADC performs a peak signal-to-noise-and-distortion ratio of 56.8dB. Our SAR ADC consumes 367nW in the simulation, corresponding to a figure of merits of 258.1fJ/conversion-step. And at lowest sample rate mode with an output rate of 126S/s, the ADC consumes only 21nW.

Abstract: The convergence of the first-order hyperbolic partial differential equations in non-Newton fluid is analyzed. This paper uses coupled partial differential equations (Cauchy fluid equations, P-T/T stress equation) on a macroscopic scale to simulate the free surface elements. It generates watershed by excessive tensile elements. The semi-discrete finite element method is used to solve these equations. These coupled nonlinear equations are approximated by linear equations. Its super convergence is proposed.

Abstract: This paper covers the development of two piezoelectric actuators for trailing edge flap control on mach scaled model helicopter rotors. The design, analysis and bench tests of these two actuators are described. Under different voltages and frequencies, their drive performances are tested and compared. Results showed that these two actuators all can effectively drive and control the flaps with each advantages and disadvantages.