Applied Mechanics and Materials Vols. 571-572

Abstract: According to Maxwell equations and constitutive relations in chiral medium, the dispersion characteristic of the symmetric slab waveguide with chiral negative refractive medium is studied. The dispersion equations expressed in the normalized parameter are deduced in the slab waveguide. The numerical results show that the chiral parameter has great influence on the dispersion characteristic of slab waveguide. When the relative chiral parameter is about 0.0477, the zero order mode of left-handed polarized wave disappears. While it is greater than 1, the core becomes chiral negative refractive medium and the zero order mode disappears. In addition, compared with the general chiral waveguide, the tendency of dispersion curves in slab waveguide with chiral negative refractive medium is also analyzed.

Abstract: The characteristics of a chiral negative refraction parallel-plate waveguide under PMC boundary are studied theoretically, and the corresponding dispersion relations, cut-off frequencies, propagating guided modes are obtained. Some novel features are found, such as fundamental mode will be not exist only if the chirality parameter κ>1, in addition, the cutoff frequency is no longer the conventionally defined frequency when propagation constant is zero, but the least frequency that guided mode can still propagate. According to the relations between propagation constant β and wavenumbers k₊,k_-, the dispersion curves are divided into three regions , and the electromagnetic field components in the regions are analyzed in detail.

Abstract: Many domestic and international scholars carried on LCA method research to wind power generation system, but generally focused on the large megawatt wind power generation system rather than SWPGS Small Wind Power Generation Systems (power rating less than 1kw).The different structural between large wind turbine and small wind turbine led to the different system boundaries and evaluation models in LCA. So this paper puts forward to establish LCA database based on Geographical Information System (GIS) and establish evaluation model based on Agent-based Modeling (ABM) method, which can provide references for LCA direction of the further deeper follow-up research.

Abstract: The started motors are characterized by the low staring torque and large currents when the motors draw the heavy-loads. Therefore, a method of motor discrete variable frequency soft starting based on the variable reactance is presented in this paper [1,2]. According to the topological structure and working principle of motor discrete variable frequency soft starting based on the variable reactance, the simulation model of the system has been set up by the Matlab/Simulink tool. Simulation results show that the motor starters developed with this method have been successfully applied to the loads of the drive equipment in the kiln, coal grinding mill or the mine. It can improve the starting performance when the motors draw the heavy-loads., save energy, stabilize the voltage of the power supply network.

Abstract: Based on actual hydraulic structure, the linear and nonlinear hydro power system model with surge tank was established for the first time. The simulation results of model demonstrate that the linear model with surge tank and that of individual penstock exists essential difference. The step response of individual penstock model is monotonic rising up to stable state, but that of model with surge tank is vibrating badly. The nonlinear model with surge tank is dynamic stable.

Abstract: By employing INC algorithm based on power estimates and variable step ,the MPPT controller can optimize the judgement if the PV cell can reach the MPP, using the comparison between estimate power and realistic power and optimize the variable step size algorithm judging by the position of work state point . The simulation results show that the controller still has good dynamic performance even when irradiance changes sharply.

Abstract: A novel boost converter named tri-state boost converter is introduced in this paper. According to the operation principle of the tri-state boost converter, the Euler-Lagrange model is set up. Based on the passivity-based control theory and Euler-Lagrange model, a passivity-based controller of the tri-state boost converter is designed. By damping injecting, the input current and output voltage of the tri-state boost converter can reach the desired equilibrium values rapidly. The speed of the tri-state boost converter to reach the desired equilibrium values varies when the damping values changes. The controller is simple to design and makes the tri-state boost converter having better dynamic and steady performances. The passivity-based controller proposed in the paper is proved feasible by simulation results.

Abstract: In order to guarantee the stability working of internal circuit of switching power supply, an internal power supply circuit with stabilization output was designed in this paper. Based on the voltage stabilization principle of zener diode, the internal power supply circuit put the high input voltage into 5v output voltage. Because of using module circuit, the circuit structure is simplified effectively. Based on 0.35um BCD technology, the internal power supply circuit was built in PSPICE. According to the experimental result, the internal power supply circuit can output stably in different input voltage and environmental temperature.

Abstract: In order to better solving the problem of electronic equipment maintenance training, promoting the level of management and usage to electronic equipment. The design method of virtual maintenance training system for electronic equipment is discussed in this paper based on virtual reality technology. Simulation results show that the system can well implement virtual maintenance training for the electronic equipment, and has certain reference value to develop other relevant system.

Abstract: In order to improve the performance of the rectifier under unbalanced voltage condition, this paper adopts port-controlled Hamiltonian dissipation (PCHD) control strategy. On the basic of the mathematical model of the three-phase voltage source PWM rectifier, its PCHD model in synchronous dq coordinates was established by orthogonal transformation. The desired equilibrium point of the system was obtained according to the target of the design. The controller was designed with the method of interconnection and damping assignment, and the PI control method was introduced to restrain the steady-state error of DC side. Simulation results show that the designed control system has perfect static and dynamic performances and robustness.