Advanced Materials Research Vol. 422

Abstract: Based on the proposed conception”pseudo-potential” of the incompressible plane flow, an exact solution to the Euler’s equation is given, f can be arbitrarily given potential force. It is proved that the given solution can describe the infinitely many unsteady vortices distributed periodically on the whole plan with the Melnikov function. It is obviously that the Brownian motion appearing along the border region separating different vortices.

Abstract: Nozzle flow model for high pressure variable-rate spraying is indispensable when orchard sprayer is controlling liquid flow based on Pulse Width Modulation (PWM) technology. Three flow models for Teejet AITXA 8002, 8003 and 8004 nozzles are obtained by using nozzle flow model test system which is established in this paper. The results from equation hypothesis test and test for lack of fit of flow model shows that those three flow models work well. Nozzle flow model validation trials show that the relative errors of model flow and actual flow are small, while the maximum relative error is 6.50%; the flows characteristics of different nozzles with the same type are almost the same.

Abstract: Navigation light monitoring system is designed to detect the working condition of each light with circuit cable carrier. However, the real-time detecting information could be inaccurate as a result of the existence of disturbances such as noise, multi-path effect and channel decline, when the data transmission happens in light cable as the channel. In this paper, OFDM (Orthogonal Frequency Division Multiplexing) is presented to be used in circuit cable communication. And the reason and capability of the resistance to these disturbances in OFDM are analyzed. Finally, the result is concluded that OFDM used in navigation light cable channel is feasible.

Abstract: Portability has become an inevitable trend of spectrometer. Faced with the trend, one micro fiber-optic spectrometer hardware circuit system, which regarded XC3S250E as master chip to control CCD scan, A/D conversion and USB data transmission, etc, was designed, and the corresponding circuits were designed. After consecutive spectral scan test, we can find that the designed spectrometer is able to complete the acquisition, conversion and transmission of spectrum. The system stability is very good and the scanning accuracy can reach 1nm.

Abstract: According to the status that most of the present measurement methods and systems should be make experiments in laboratory, which need collect samples from spot, then carry to laboratory. Base on parallel hot wired method theory and single-chip technology, conduct a research on portable measurement method of loose coal thermo-physical parameters, then can test thermal conductivity and diffusivity of loose coal out of laboratory, the measurement system is developed. The experiment shows that results of thermal conductivity and diffusivity are well repetition, and agree with the reference value of relative literatures. The application of this system will provide convenience for occasion that need get the loose coal thermo-physical parameters quickly.

Abstract: A SO₂ on-line monitoring system (CEMS) has been developed by the author based on the principle of electrochemistry. This system consists of SO₂ mass concentration monitoring subsystem (the subsystem had been described in on-line system for monitoring SO₂ in fumes（1）) and SO₂ flow velocity and flow rate monitoring subsystem. In the paper, the working principle and procedure of SO₂ flow velocity and flow rate monitoring subsystem are described in detail. In the meantime, an advanced method for measuring average flow velocity of fumes by mean of “velocity field constant” is presented. A innovative device has been developed to detect velocity field constants automatically, which has resolved the technical difficulty in automated monitoring of fumes average velocity in the flue.

Abstract: To solve the problems of concrete piston striking cylinder and pumping insufficiency caused by the mismatch between varying loads and system’s open-loop control property, the optimal model of concrete pumping displacement control was built.To be precise, the displacement control signal parameters were taken as control variables, and the location parameter of the main cylinder’s displacement sensor was taken as structure variable. under the physical constraint condition of non-collision between piston and cylinder, the piston stroke maximizing was taken as objective function and the optimal model of concrete pumping displacement control was built.Optimization result shows that piston of concrete pumping system don’t strike cylinder and pump sufficiently under varying loads.This optimal model, which is built in the integration design space of structure variable and control variables, is of guiding significance for solving open-loop system’s engineering control problems.

Abstract: Based on giant magnetostrictive material, a new design of pneumatic high speed on-off valve is presented in this paper. To settle the problem of balancing fast response and large flow, a cantilever beam is employed as both displacement amplifier and valve spool in the innovation structure of the valve. The dynamic model of the valve is established by analyzing the dynamic performances of the giant magnetostrictive actuator and the cantilever beam, based on the theories of electromagnetism and the mechanical vibration. A simulation on this model is carried out to investigate the performance of the valve. Results of the simulation show that the new pneumatic high speed on-off valve is able to achieve the goal of high frequency response, while satisfying the requirement of a large flow.

Abstract: As electro-hydraulic control system of strip steel CPC has some special characteristics, such as strong nonlinear, changes in structural parameters, serious time-delay and the very difficultly of establishing accurate mathematical model, the integral-separate PID improved predictive control algorithm was proposed on the basis of the new mathematical model. Firstly, the integral-separate PID algorithm was used to make system asymptotic stability and reduce overshoot of system. Secondly, the predictive control algorithm was proposed, error feedback correction model was improved, and predictive control signal was optimized with rolling method. Finally, the system was simulated and analyzed in noise and pulse disturbance. The simulation results show that this algorithm can effectively improved abilities of anti-noise and anti-load disturbance, increases robustness and tracking capability of strip steel CPC system; furthermore, it can improved speed of system response and decrease time-delay and overshoot of system. Therefore, this algorithm can well meet the need of electro-hydraulic control system for strip steel CPC system.

Abstract: Due to the problems about Lubrication and sealing in water hydraulics, the poor performance, large leakage, extreme requirements of processing, high cost and poor anti-pollution properties exist in water hydraulic servo or proportional valves of spool structure and analogue control. A better seal is provided by the structure of the poppet valve comparing to the spool valve, however, poorer linearity and control accuracy accompanying inevitably. Aiming at improving the control performance of poppet valve, the design of the multi-digit numerical control valve is analyzed in this paper. The novel design using ball seat valves for digital bits is proposed to ensure enough seal ability and lower the cost. The simulation model of the multi-digit numerical control valve is built in AMESim software and the results show high linearity in flow control. However, large overshoot and oscillation encounter during the switching of the digits. Especially the switching process of the high digital bits requires to be regulated to reduce the large overshooting. The adjustment of the spring in the sensitive chamber of the bit valve can decrease the overshoot and improve the stability. These above contribute to the improvement of the control performance of water hydraulic control valves and applications of water hydraulics in the industry.