Advanced Materials Research Vols. 466-467

Abstract: According to the requirement of operational stability and reliability of welding robot, the direct and inverse kinematics models of three-axis linkage welding robot were analyzed. Based on the analysis result, variable gain PID control scheme was designed, and the control system model was built. The control scheme was checked and assessed using MATLAB analysis box. Analysis results show that control system satisfies the demands of welding robot running stability and reliability in ideal status, and the research has laid foundation for the further research.

Abstract: BP neural network is currently the most widely used of neural network models in practical application in transformer fault diagnosis. BP algorithm is a local search algorithm which is easy to make the network into the local minimum values. Network training results are poor. It discusses PSO-BP algorithm which combines the particle swarm optimization (PSO) algorithm with the BP algorithm in this paper. It uses PSO algorithm to optimize the BP network’s weights and threshold. It is used in power transformer fault diagnosis. Experimental data results show that PSO-BP network fault diagnosis accuracy is higher than BP algorithm.

Abstract: Because of the high-cost of the spaceflight launching, the reliability of the payload must be ensured in the high level acoustic energy produced by the first stage rocket engine. It’s the base for ensuring the normal work of the instruments during the lift-off. In this paper, the exhaust noise and the specific sound field produced by the liquid rocket engine on the ground-test system were measured, and the statistical energy analysis model was built to predict the noise environment of the rocket engine. In order to obtain the noise spectrum loaded on the fairing and the instrument cabin during the lift-off, two measurements were made and some measuring locations were set for each test. During the testing, the sound pressure level around the engine spout and the corresponding heights of the payload cabin were measured. By comparing the data derived from different measuring locations for the same measurement and the different measurements for the same location, the characteristics of the noise field was obtained. Results showed that the measured data agreed well with the predicted data used AutoSEA2 software.

Abstract: A clamping mechanism for use in relatively the bearing capacity of the pipneline is described. The force analysis of the clamping mechanism is performed according to the operation of the deepwater flange connecting tool, and the clamping force of the clamping mechanism is determined according to the ultimate working condition of the deepwater flange connecting tool. At the same time, the strength and stability of the pipeline are also calculated using the thin-wall strength theory, and it is proved that the clamping force of the clamping is appropriate. The findings provide a theoretical basis for structure design and optimization of the clamping of the deepwater flange connecting tool.

Abstract: This article analyses the electromagnetic interfering sources and its transmitting ways inside electric driving system controller and expounds the anti-disturbing methods in designing the electromagnetic compatibility of electric driving system controller. Among that the interfering sources are the rectifiers and inverse transformer in the AC frequency converter and the interference signals from electric network, the transmitting ways of the electromagnetic interfering signals include transmitting in electric wires, radiating and coupling through space, and the anti-disturbing methods have (a) separating interference sources with the system or devices, (b) connecting filters in the output ends of interfering sources and the input ends of the devices easily to be interfered, (c) shielding the interfering sources, (d) grounding correctly and reliably, (e) adding circuit power filters. The experimental results demonstrated that the anti-disturbing methods mentioned above are very effective for the electric driving system controller based on computer control.

Abstract: In order to improve voltage utilization ratio and dynamic performance of frequency converter, this paper presents a digital frequency converter design scheme based on digital signal processor TMS320LF2407A and the theory of space vector pulse width modulation (SVPWM) technology, provides its detailed design measures of software and hardware and SVPWM algorithm realization methods. The experimental results prove that this new frequency converter has simple structure, high control precision, higher voltage utilization ratio, better dynamic and static property.

Abstract: Based on the electro-magneto-elastic theory and the theory of the bending vibration of the electric beam, nonlinear vibration equation of current-carrying beam in thermal-magneto-elasticity field is studied. The Lorentz force and thermal force on the beam are derived. According to the method of multiple scales for nonlinear vibrations the approximation solution of 1/3 subharmonic resonance of the system is obtained. Numerical analysis results show that the amplitude changed with the system parameters.

Abstract: This paper proposed a kind of new control method for resolving the problem of the Direct Torque Control (DTC)'s greater torque pulsation problem at low speed, this method is based on Space Vector Pulse Width Modulation (SVPWM). SVPWM is a kind of excellent Pulse Width Modulation (PWM) scheme. It can not only improve the inverter DC voltage utilization, reduce harmonic losses, restrain torque pulsation, also easily generate high-precision real-time waveform by the high-speed digital signal processor. The simulation results of this system by Matlab/Simulink indicate that the space vector PWM direct torque control can efficiently reduce the pulse of motor torque and flux linkage.

Abstract: We need to hold flow characteristic for water- and/or oil-sediments, with low-middle volume fraction of the particles in horizontal flexural pipes, in order to design logging tool and build interpretation methods for the producing profile. To achieve this, we built governing equations and boundary conditions for the water- and/or oil-sediments based on the mixture algebraic slip model (MASM), and gained numerical solution by the finite difference method and the successive over relaxation. 3-D simulation results in flexural horizontal pipes indicated that volume of oil is obviously greater than that of water in the downhill but opposite in upgrade. When the velocity in the entrance is small enough, “die oil” perhaps presents at top of the borehole in downhill. Moreover, this entrance velocity arisen “die oil” is increasing with height of interface. The volume of deposited particle in lowest location is reducing with increasing the entrance velocity when the entrance velocity is small and increasing with the entrance velocity when the entrance velocity is large, and slant surface of deposited particle volume is gradually emerged. This is due that deposited particles are hiked once again and carried forward when the flow velocity is greater than incipient velocity for a particle size.

Abstract: The mathematical model of Three-phase VoltagePulse Width Modulation (PWM) DC/AC inverter is non-linear, in view of the traditional linear control strategy can not meet the requirements of designing high-performance DC/AC inverter, this paper propose a new nonlinear control strategy for Three-phase Voltage PWM DC/AC inverter called Passivity-based Control. We can alter the inverter model in three-phase abc coordinate to two-phase synchronous rotating dq coordinate for establishing the Euler – Lagrange (EL) energy model for this system, then we also proof this system is strictly passive. We can control the output energy of the system, and we use the approaches of injecting damping and decoupling to improve system performance. Usually, we can use Single Chip Microcomputer or other kinds of computer with this algorithm for our design, this algorithm can be programmed with the computer language, such as C/C++ and assembly language, etc. Simulation results show that passivity-based control method can make this system possess the high-performance of robustness and dynamic.