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This paper presents an exhaustive simulation study performed to validate the adequacy of the equivalencing method promoted by the National Renewable Energy Laboratory for modeling wind power plants by single- and multiple-machine equivalents. The main simulation results are presented for a number of steady state and transient wind turbine generator operating conditions following various faults and a typical low-voltage ride through. The impact of protection systems such as the crowbar is also taken into account. The aggregation technique has shown to be adequate for load flow, stability, and electromagnetic transient studies with limitations, as presented in the paper. [ABSTRACT FROM AUTHOR]

The Warp code (and its framework of associated tools) was initially developed for particle-in-cell simulations of space-charge-dominated ion beams in accelerators, for heavy-ion-driven inertial fusion energy, and related experiments. It has found a broad range of applications, including nonneutral plasmas in traps, stray electron clouds in accelerators, laser-based acceleration, and the focusing of ion beams produced when short-pulse lasers irradiate foil targets. We summarize novel methods used in Warp, including: time-stepping conducive to diagnosis and particle injection; an interactive Python-Fortran-C structure that enables scripted and interactive user steering of runs; a variety of geometries (3-D $x$ , $y$ , $z$ ; 2-D $r$ , $z$ ; 2-D $x$ , $y$ ); electrostatic and electromagnetic field solvers; a cut-cell representation for internal boundaries; the use of warped coordinates for bent beam lines; adaptive mesh refinement, including a capability for time-dependent space-charge-limited flow from curved surfaces; models for accelerator lattice elements (magnetic or electrostatic quadrupole lenses, accelerating gaps, etc.) at user-selectable levels of detail; models for particle interactions with gas and walls; moment/envelope models that support sophisticated particle loading; a drift-Lorentz mover for rapid tracking through regions of strong and weak magnetic field; a Lorentz-boosted frame formulation with a Lorentz-invariant modification of the Boris mover; an electromagnetic solver with tunable dispersion and stride-based digital filtering; and a pseudospectral electromagnetic solver. Warp has proven useful for a wide range of applications, described very briefly herein. It is available as an open-source code under a BSD license. This paper describes material presented during the Prof. Charles K. (Ned) Birdsall Memorial Session of the 2013 IEEE Pulsed Power and Plasma Science Conference. In addition to our overview of the computational methods used in Warp, we summarize a few aspects of Ned's contributions to plasma simulation and to the careers of those he mentored. [ABSTRACT FROM PUBLISHER]

In the paper, a novel approach to numerical modeling of tube induction welding is proposed. The coupled electromagnetic and thermal model must take into account also the movement of the metal strip: in order to make possible this kind of simulation in reasonable computation time, a simplified approach to the modeling is presented and discussed. [ABSTRACT FROM PUBLISHER]

Real-time electromagnetic transient simulation plays an important role in the planning, design, and operation of power systems. Inclusion of accurate and complicated models, such as the universal machine (UM) model and the universal line model (ULM), requires significant computational resources. This paper proposes a digital hardware emulation of the UM and the ULM for real-time electromagnetic transient simulation. It features accurate floating-point data representation, paralleled implementation, and fully pipelined arithmetic processing. The hardware is based on advanced field-programmable gate array (FPGA) using VHDL. A power system transient case study is simulated in real time to validate the design. On a 130-MHz input clock frequency to the FPGA, the achieved execution times for UM and ULM models are 2.5 \mu\s and 1.42 \mu\s, respectively. The captured real-time oscilloscope results demonstrate high accuracy of the emulator in comparison to the offline simulation of the original system in the EMTP-RV software. [ABSTRACT FROM PUBLISHER]

This paper develops a parallel fast multipole method specialized for uniform brick elements to achieve large-scale micromagnetic simulations of a practical perpendicular recording head within acceptable computation time. In highly parallel computation, it is indispensable to equally distribute the computing load among processes so as to obtain the good parallel speedup. The load balancing technique which can be regarded as the domain decomposition method based on octree structure in the fast multipole method is discussed. The scalability of the parallel fast multipole accelerated micromagnetic simulation is investigated with 100 or more MPI processes. [ABSTRACT FROM AUTHOR]

Cellular phones are used in the vicinity of the human head, resulting in localized exposure to this part of the body. To simulate exposure during cellular phone use, microwave energy absorption should be focused within the head region of laboratory animals. In this paper, we developed an exposure system using a figure-8 loop antenna to permit localized exposure of a rat head to 1500-MHz microwave fields, simulating human head exposure to cellular phones. We have numerically estimated the specific absorption rate (SAR) in a rat exposed to microwave fields via our new exposure system. The high ratio of SAR averaged over the target tissue (i.e., the brain) to that averaged over the whole body suggests that the figure-8 antenna can realize greater localized exposure than the previously used exposure system. We have also confirmed the effectiveness of our proposed system experimentally. [ABSTRACT FROM AUTHOR]

This paper presents a new neural-network method to describe the electromagnetic (EM) behavior at the interface between the substructures from an internally decomposed EM structure. A set of neural networks is used to represent the EM behavior of the substructure as seen from the interface. This allows EM coupling between substructures to be effectively represented. The method is developed in a finite-element environment. An EM transfer function matrix is formulated to produce training data, allowing neural networks to learn the spatial coupling between EM-field variables at various locations over the interface of the substructure. A new formulation is proposed where trained neural networks are integrated into the finite-element equation for efficient simulation of an overall EM structure. A technique is developed to allow the proposed model to be used with the mesh different from that in neural-network training. Examples show that the proposed method provides better accuracy than conventional neural-network approaches for modeling substructures from an internally decomposed EM problem. Using the proposed model also speeds up finite-element simulation. [ABSTRACT FROM AUTHOR]

In this paper, applying field orientation based on particle swarm optimization (PSO) controls the speed of two- asymmetrical-winding induction motor. The maximum efficiency of the motor is obtained by the evaluation of optimal rotor flux at any operating point. In addition, the electromagnetic torque is also improved while maintaining a fast dynamic response. In this research, a novel approach is used to evaluate the optimal rotor flux level. This approach is based on PSO. This research presents two speed control strategies. These are field-oriented controller (FOC) and FOC based on PSO. The strategies are implemented mathematically and experimentally. The simulation and experimental results have demonstrated that the FOC based on PSO method saves more energy than the conventional FOC method. [ABSTRACT FROM AUTHOR]