SIMULATION: Transactions of The Society for Modeling and Simulation International

Gupta, Santosh Kumar; Baishya, Srimanta

doi: 10.1177/0037549714544336pmid: N/A

In this paper a comprehensive study of Junctionless Single Metal cylindrical surround gate (JLSM CSG) metal-oxide–semiconductor field-effect transistor (MOSFET) characteristics have been presented and compared with a conventional CSG MOSFET of identical dimensions. The variations of different analog and radio frequency performance parameters have been studied by varying the gate length, channel diameter, and metal gate workfunction using three-dimensional numerical simulations in terms of transconductance, transconductance generation factor, early voltage, unity gain cutoff frequency, maximum frequency of oscillation, etc. The JLSM CSG MOSFETs are found to exhibit superior characteristics compared to the conventional CSG MOSFETs.

Iranian, Mohamad Esmaeil; Yousefi, Iman; Shoorehdeli, Mahdi Aliyari

doi: 10.1177/0037549714547283pmid: N/A

A real-time dynamic hardware-in-loop (HIL) simulator of an RTX real-time subsystem (RTSS) was developed by using LabVIEW (G language). The main idea of this work was to determine the feasibility and accuracy of widely available and highly competitive commercial products, such as personal computers on an RTSS, as an alternative to conventional prohibitive real-time simulators in dynamic studies of power systems. The implemented system is a self-contained heavy-duty gas turbine, governor, synchronous 200-MVA, 15.75-kV machine and a simplified electrical network. The HIL simulator was customized to interact with a 1518-kW static exciter. The role of this HIL simulator is to provide real-time digital and analog signals for static exciter systems (SES) and to simulate the mechanical and electrical components in a closed-loop, fixed-step solver applied by a well-known numerical solution method. This sophisticated yet exceptionally economic HIL simulator provides engineers with a safe environment to analyze the dynamic performance of static exciters and investigate their natural restraints and functionalities. It also provides a safe environment to analyze some naturally destructive tests.

Xiao, Hui; Lee, Loo Hay

doi: 10.1177/0037549714548095pmid: N/A

A method is proposed to improve the efficiency of simulation optimization by integrating the notion of optimal computing budget allocation into the genetic algorithm, which is a global optimization search method that iteratively generates new solutions using elite candidate solutions. When applying genetic algorithms in a stochastic setting, each solution must be simulated a large number of times. Hence, the computing budget allocation can make a significant difference to the performance of the genetic algorithm. An easily implementable closed-form computing budget allocation rule of ranking the best m solutions out of total k solutions is proposed. The proposed budget allocation rule can perform better than the existing asymptotically optimal allocation rule for ranking the best m solutions. By integrating the proposed budget allocation rule, the search efficiency of genetic algorithms has significantly improved, as shown in the numerical examples.

Papadopoulos, Alessandro Vittorio; Leva, Alberto

doi: 10.1177/0037549714547296pmid: N/A

Modelling and simulation nowadays permeate virtually any engineering activity, requiring tools capable of managing complex models efficiently. Nonetheless, whereas modern modelling languages and tools allow such models to be constructed even on lightweight platforms (e.g. a laptop), the same is not true when it comes to numerically integrating those models. For the latter purpose, modellers usually pursue efficiency by resorting to approximation and reduction techniques. However, such techniques are unnatural to include in modelling and simulation tools. This is particularly true with object-oriented ones, which on the other hand are the most interesting for dealing with complexity from the model construction viewpoint. This paper presents a novel approximation technique that can be easily included in modelling and simulation tools, and relates the proposal to literature alternatives so as to provide evidence of its peculiarities. An extended manipulation toolchain is also proposed, allowing for the introduction of other (classical) efficiency-targeted approximation techniques, within a unified framework. Some application examples illustrate the achieved advantages and motivate the major design choices from an operational viewpoint.

Werberich, Bruno Rocha; Pretto, Carlos Oliva; Cybis, Helena Beatriz Bettella

doi: 10.1177/0037549714547295pmid: N/A

This paper presents a pedestrian route choice model devised to represent the influence of the impedance generated by other pedestrians on the route choice process. This model is inspired by friction force equations, and considers that pedestrians avoid passing near other pedestrians with high relative velocity. The route choice process is based on a weighting of the impedance generated by pedestrians and the path length. A social force model was used to model pedestrian walking behavior. The model is able to reproduce emergent behavior among agents, allowing the assumption that the friction equations may provide a suitable approach to route choice behavior and can also be used as an indirect measure of pedestrian delay.

Huber, Daniel; Fowler, John; Armbruster, Dieter

doi: 10.1177/0037549714546665pmid: N/A

This paper presents two algorithms to analytically approximate work in process (WIP)-dependent inter-departure times for tandem queues composed of a series of M/M/1 systems. The first algorithm is used for homogeneous tandem queues, the second for such with bottlenecks. Both algorithms are based on the possible combinations of distributing the WIP on the queues. For each combination the time to the next departure is estimated. A weighted average of all estimated times of each WIP level is calculated to get the expected mean inter-departure time. The generated inter-departure times are used in a simple model of the tandem queue. The inter-departure times, the average WIP and average cycle time of the tandem queue and the simple model are compared in several tandem queue parameterizations. Results show only a small error between the simple model and the tandem queue, rendering this approach applicable in many applications.