Papers by Keyword: PFC

Abstract: Infilling rock joints widely exist in natural rock masses, and the shear failure of infilling rock joints plays an important role in the instability of rock masses. In order to study the shear failure mechanism of infilling rock joints, Particle Flow Code is used to simulate the direct shear test of infilling rock joints. The PFC models with different infilling thickness are established firstly, and then the procedures of PFC simulation are described. In the end, the shear failure process of infilling rock joints with different infilling thickness is simulated. Based on the PFC simulation results, it can be concluded that the shear failure mode changes with increasing infilling thickness, and the shearing of the infilling rock joint rarely gives birth to microcracks in rock due to the existence of the infilling material.

Abstract: The calibration of micro-properties of bonded particle model (BPM) is usually artificially accomplished by the means of trial and error which has some intrinsic drawbacks such as high time consumption, arbitrariness, uncontrolled accuracy, etc. In order to overcome these shortcomings, the optimization inversion method based on the asynchronous particle swarm algorithm is proposed to estimate the micro-properties of BPM in PFC. The optimization model is firstly established by formulating the objective function and related constraint conditions, and then the procedure of optimization inversion is presented. Furthermore, a FORTRAN program called PIBPM is developed for the realization of the proposed method. The feasibility of the proposed method and the correctness of PIBPM are verified through an application example.

Abstract: The stability of rock masses is controlled by the shear behavior of rock discontinuities, and it is hard to investigate the shear behavior of rock discontinuities at micro-scale by using traditional physical test method. With this in mind, Particle Flow Code is used to simulate the direct shear test of rock discontinuities. The PFC model of rock discontinuities is established firstly, and its micro-properties are inversed by using the proposed optimization inversion method based on the asynchronous particle swarm algorithm. Then, the PFC simulation of shear behavior of rock discontinuities is performed. The simulation results show that the number of microcracks gradually increases with the increasement of shear displacement, and the accumulated microcracks result in the shear failure of rock discontinuities.

Abstract: Design a battery with a power factor correction two level converter structure of charging power supply .Discuss the design scheme of main circuit and control circuit. Expound the calculation method of the key element parameters. The experiments indicate that the device get a good performance on output and reliability. The source is appropriate for all types of Battery charging.

Abstract: Based on the full analysis of the LED drive power of active and passive (PFC) circuit, the active and passive (PFC) circuits of the LED drive power are performed a detailed analysis, and the types, series and mode of the PFC circuit are also described in detail, the working principles of the valley fill circuit and APFC boost converter are mainly analyzed. Based on those studies, an APFC circuit is given by the use of L6562A and a simple application of APFC circuit presented.

Abstract: This paper described new working mode of Power Factor Corrector (PFC), called Boundary Continuous Mode (BCM); studied the design parameters of the critical components for the BCM-PFC in the boost topology; proposed a method and a tool for designing an L6562A-based BCM-PFC Boost Converter. The method and tool was verified on an evaluation board emulating a PFC boost converter with an 80W output power, 400Vdc output voltage and a wide range main input from 85Vac to 264Vac; and it can be easily adapted for applications with higher output power around 400W.

Abstract: A 100W adaptor with universal voltage range 90-265VAC input and 20V/5A output is designed in this paper .The prototype adopted a new level two-stage high power factor power adapter, the PFC(Power Factor Correction) is a Boost converter operating in discontinuous current mode boundary,and the DC/AC using flyback converters. The experimental results showed that the effectiveness of the proposed approach.

Abstract: This paper proposes the modeling of Single Ended Primary Inductor Converter (SEPIC) for Power Factor Correction (PFC) and PID control for the converter using various tuning methods. The SEPIC is capable of operating from an input voltage that is greater or less than the regulated output voltage. A small signal dynamic model for SEPIC PFC converter is obtained using state space averaging technique which provides a fifth order transfer function. The complete model of the converter is simulated using MATLAB (SIMULINK). Then the PID controller is designed for the SEPIC PFC converter and various tuning methods were adopted using SISO tool in MATLAB.

Abstract: Due to the complication of grouting process in soil, design of fracture grouting works is still mainly based on empirical considerations and experiences from past projects. Based on the theory of particle flow, the domain of flow is defined by using Fish language implemented in PFC and the formulas for flow and pressure are put forward respectively. Combined with above study, the process of fracture grouting in soil is simulated with particle flow code (PFC2D) from micro-viewpoint under coupling environment. In addition, the emergence and development of crack and grouting pressure in soil is analyzed under different grouting pressure and soil properties. The research results show that pressure plays a key role in consolidating the soil by fracture grouting, but in fact it should be kept in a reasonable value in order to forming grouting slurry net entirely. Filed test indicates that fracture grouting greatly increases the bearing capacity of weathered rock in Xiamen Xiangan subsea tunneling and the conclusions of numerical simulation agrees well with the field test and grouting theory.

Abstract: To study the microscopic mechanism of stress-induced anisotropy for coarse-grained soil, with PFC(particle flow code) numerical simulation method, many planar biaxial test samples composed of regular disk particles or irregular clump particles were prepared, different initial stress states were given, and equal stress increment was applied on different directions. Then, initial elastic modulus and stress-induced anisotropy property were got, and analysis of its microscopic mechanism of stress-induced anisotropy was given. Results shows, the stress-induced anisotropy of coarse-grained soil occurs under the interaction of internal irregular microscopic structure and external non-isotropic stress.