Applied Mechanics and Materials Vols. 130-134

Abstract: During the reciprocating motion, the sucker rod string of the pumping wells will produce longitudinal vibration, lateral vibration and torsional vibration under various loads, the rod combination and structure often affect the fatigue fracture and releasing of the sucker rod string. Based on the ANSYS (finite element analysis) method, this article made an analysis for the vibration characteristics of sucker rod string, and studied the steady-state response of suspension point movement and the pumping load, mastered the influence law of vertical, horizontal and torsional natural frequency with different rod combinations, acquired the steady-state response under the two main loads of suspension point motion and pumping load. This article made a great significance for scientific design of sucker rod string and preventing broken off accidents of sucker rod string.

Abstract: This paper develops a superior injector driving circuit for a 500c.c. motorcycle GDI engine. The POWER MOSFET component is introduced in the design of the three-pulse injector driving circuit. Experiments for the designed electric driving circuit are investigated to verify its feasibility. The experiments of the H.P. injector driving circuit are conducted for the fuel injection quantity of the H.P. injector under 80~100 bar fuel pressure, 1200~2000 μs injection pulse duration and DC 55~65V power supply voltage. PWM control is introduced to the last pulse 3A holding current for fast cut-off response time of the H.P. injector. Next, Taguchi method was used to lead the design of experiments (DOE). The fuel injection quantities were measured in the various control parameters as engine speeds, power supply voltages, injector driving currents, and fuel supply pressures by the designed injector driving circuit. Effect of these control parameters of the high-pressure (H.P.) injector driving circuit on the fuel injection quantity are analyzed in the paper. Taguchi orthogonal array optimizes the operating parameters of the H.P. fuel injecting system. Results show that the three-pulse POWER MOSFET injector driving circuit is capable of operating stably and assure the accurate injection quantity of the H.P. injector.

Abstract: Analysis the wiring of head and tail pully driving & bidirectional 6KV motor，and found the reason of negative phase sequence over current protection malfunction did occur when the motor ran in the reverse direction , then compared the solution methods to make sure which one is better. At last use the method that change the sampling program to make the motor negative phase sequence over current protection wil in effect.

Abstract: In order to reap the benefits promised by the Smart Grid, communications between the IEDs in IEC 61850 Substation Automation System (SAS) will need to be made much more secure.Traditional security solutions based on Public Key Infrastructure (PKI) are calculation intensive and introduces latency that will be difficult to meet substation environmental and electrical requirements, so they are not well suited for IEC 61850 SAS. Identity based encryption (IBE) schemes, introduced by Shamir in 1984 [5] are based on the idea to use participant’s unique identities as public key and public key directories are unnecessary. Thus, utilizing IBE in IEC 61850 SAS is a reasonable choice. This paper briefly introduces the features of IEC 61850 SAS communication security and IBE and then propose an IBE-based Self Private Key Generated (SPKG) encryption scheme to establish encryption system in IEC 61850 SAS. Advantages of this SPKG Scheme are also discussed in the paper.

Abstract: The empty orbital model in perovskite ATiO₃-type (A=Mg, Ca, Sr and Ba) ferroelectrics with oxygen octahedra has been proposed. In this study, the impact of temperature on the bond energy of Ti-O has been discussed from the point of view of statistical thermodynamics, then the temperature dependence of equilibrium position of Ti ion has been calculated. The results show that because of the existence of empty orbital, with temperatrue decreasing the repulsion energy of Ti and O ions reduces and the Ti ion shift the equilibrium position in the cooling through the Curie temperature owing to Coulomb interaction. Ferroelectric phase transition in perovskite are successfully explained. Theoretical and experimental results for perovskite ATiO₃-type ferroelectrics are compared and discussed.

Abstract: Considering that the capacitance value of thyristor controlled series capacitor (TCSC) can be adjusted quickly in capacitive mode, and that accumulated energy can be released in bypass mode. A control strategy is presented for improvement of dynamic stability in multi-machine power system. TCSC inputs maximum capacitive compensation in a appropriate time when equivalent generator of multi-machine power system accelerates relative to center of inertia (COI) after a fault, yet TCSC operates in bypass temporarily mode for deceleration. TCSC adopts conventional dynamic control during other time. By IEEE4 machine 10 nodes system simulation experiment, the effectiveness of the controller is verified.

Abstract: A 2D fully thermal mechanical coupled finite element model is applied to study the influence of material parameters on serrate chip formation during high speed cutting process. The serrated chip formation during high speed machining was predicted. Of interests are the effects of thermal conductivity, specific heat and density. Results showed significant influence of these thermophysical parameters on the serrated chip phenomena, especially in the case of the density. Increasing thermal conductivity specific heat and density lead to a decreasing degree of segmentation. The influence of the thermal conductivity on the cutting force and the specific heat on maximum temperatures in the shear band is also discussed.

Abstract: This paper presents a design of PMSM (Permanent Magnet Synchronous Motor) double-loop servo system based on TMS2812DSP hardware platform, programmed by C language in Q format, and using the theory of vector control along with the technique of SVPWM ( Space Vector Pulse-width Modulation). This system can get widely used in the area of motor digital control system, automatic production line, etc, which demands highly precise servo control.

Abstract: A high-performance speed sensorless direct torque control (DTC) system of permanent magnet synchronous motor (PMSM) is presented in this paper. The stator flux linkage, speed, rotor position and load torque of PMSM are observed using a fourth-order Extended Kalman Filter (EKF) and a second-order Kalman Filter (KF) and the observed load torque is used for feed-forward compensation of reference torque. Simulation results clearly demonstrate the performance of speed can be improved when load torque is changed and the validity of the proposed control strategy.

Abstract: This paper presents and compares the performance of a two-pole, three-phase slotless brushless DC motor with two types of winding configuration: concentrated and rhombic windings. Application of the finite element method (FEM) analysis to their performance calculations is performed.