Applied Mechanics and Materials Vols. 130-134

Abstract: In order to solve the problem of general fins and rudders being lower at low moving speed, the moving mass technical is applied onto AUV, thus to radically solve the weakness of control method with fin and rudder. The space dynamics model of moving mass control is created for AUV. And based on this, the moving mass control system is designed with the sliding mode variable structure control method so as to ensure system tracking error zero convergence. By controlling the moving mass movement with moving mass control system, the attitude of AVU is previously controlled. And simulation result proves that moving mass control system will control the AUV attitude angle precisely and rapidly.

Abstract: Designed a Reduced Voltage Starter for DC oil pumps in power plant, which is a Buck Converter based DC-motor soft Starter/Stopper with 220VDC power supply. In this paper, the main circuit, working principle and operating sequences of the switches of the device are clarified; and the design of each circuit unit is briefed; the transient of Buck Converter are analyzed and the snubbers for the Buck Converter are designed; at last the load test results of 55kw device are sketched. After running in a number of power plants, it's been proved that the device is an upgrade for traditional Rotor Resistance Starter, for its stability, reliability, efficiency, and intelligence.

Abstract: In this paper, the control law designing of longitudinal-lateral attitude and faults self-repairing against the UAVs are analyzed. The direct adaptive controller via fuzzy feedback is designed to guarantee the UAVs stabe and having good flying performance. Then, a new direct adaptive control method is formulated by quantum control technique. Consequently, not only the stable error but the property of response and robustness is improved well. Simulation results are given to illustrate that a good dynamic performance of the flight control system with large faults can be maintained with the proposed control method.

Abstract: This paper discusses the anti-explosion control system project for the fine powder processing. To prevent explosion, safety interlock control system is brought up. The article describes the hardware configuration and software establishment of the project, and makes suggestions for the project implement about sensor installing and program debugging.

Abstract: The load distribution of the impeller and the shape of blade bone surface as well as the pump performance are determined by the circulation distribution from the impeller inlet to the outlet. However, perfect conclusions about optimal forms of the circulation distribution have not been seen yet. In this paper, three kinds of circulation distributions were studied. Three mixed flow pump impellers with high specific speed were designed according to the circulation distributions, and the models of the three pumps were built and modeled in the commercial CFD code ANSYS-CFX 11.0. The flow field in the pumps has been investigated using large eddy simulation (LES). Experiment was carried out on one model. And the performance curves predicted by LES were compared with the experimental data, and good agreements were achieved. The results show that: there is a low pressure area at impeller outlet. The pressure distribution along the circumferential direction was asymmetry at the front-end area of guide vanes, but it becomes uniform at the end of guide vane. The bearing pressure on the pressure side of the model 2 is lower, and the pressure distribution of model 1 is more asymmetry and there is a clear low pressure area at outlet of blade; Cavitation performance of model 2 is better, and the maximum efficiency is also the highest, but the hump is more serious; Model 1 has a widest area of high effective area.

Abstract: The average model of the forward converter is build with the state-space average method. The open-loop transfer function model is deduced in detail according to the average model of the forward converter, the controller is designed based frequency domain by the type III compensation network. And the stability of the control system has been improved. The modeling and simulation of system was implemented based Matlab. The results of simulation confirm that the controller is capable of reduced steady state error and improve controller's reliability during power supply disturbance and load disturbance．

Abstract: In this paper, a broadband and simple vertical transition between substrate integrated waveguide and standard air-filled rectangular waveguide is design and experimentally verified. From full-wave simulation of the structure, a relative bandwidth of 19.5% in W-band with return loss better than 20dB is reached. Then, five copies of back-to-back connected transitions are fabricated on RT/Duroid 5880 substrate. The experimental results show that the transition pairs have an average of 15% relative bandwidth with return loss better than 12dB and insert loss lower than 1.2dB. To explain the differences between simulated and tested results, an error analysis is presented.

Abstract: This paper presents a kind of CPW-fed Pentagon-type multi-band planar monopole antenna. It provides an integrated wideband operating frequency band coverage from 900MHz of GSM to 10.6GHz UWB applications. This is the desirable antenna characteristic that is suitable for modern integrated mobile broadband wireless radio access applications. The proposed antenna was fabricated in practice with the FR4 print circuit board having 1.6 mm substrate thickness and dielectric constant of 4.4, tangent loss constant of 0.02. The measurement results show the success of the proposed planar monopole antenna. The detailed antenna design parameters are given in this paper. The characteristics of this type antenna, wide in bandwidth, low in profile, light in weight and small in size and single layer fabrication can be beneficial in the future integration with other microwave circuit of wireless systems.

Abstract: Prestressing strands are widely used in civil structures. The health monitoring of the strands is an important factor in evaluating the structural safety. This paper aims to improve the detection sensitivity of the guided wave technique in strands by wavelet processing. Groove defects with different depths are cut in the wire and detected by magnetostrictive sensors. The wavelet threshold method is employed to denoise the signals. In this study, the suitable thresholds are related to the median value of the coefficients. Results show that defects above 3.6% cross section loss can be found after this processing. Moreover, the amplitudes of the defect signals are related to the defect depths, which can be used to size the defects.

Abstract: In order to modify present simulation and test system of DT-100 Short-wave Radio’s Power Amplifier, a kind of automatic test system for short wave radio’s power amplifier is designed here in which virtual instruments and MCU technology are used. Compared with the earlier systems, the new test system avoids many weaknesses, such as complicated simulation test, tedious testing process, and huge manual calculations and has merits of simple operation and accurate assessment all of which provide a better way for existing testing system.