Modeling And Simulation Research Articles

Modeling and Simulation in Transportation Engineering 2014

[Wang, Wuhong] Beijing Inst Technol, Dept Transportat Engn, Beijing 100081, Peoples R China. [Wets, Geert] Hasselt Univ, Transportat Res Inst IMOB, B-3590 Diepenbeek, Belgium. [Bubb, Heiner] Tech Univ Munich, Inst Ergon, D-85747 Munich, Germany. [Niu, Huimin] Lanzhou Jiaotong Univ, Sch Traff & Transportat, Lanzhou 730070, Peoples R China. [Chen, Hong] Changan Univ, Sch Highway, Xian 710064, Peoples R China. wangwuhong@bit.edu.cn

Modeling and Simulation of BLDC Motor for Minimizing the Cogging Torque, Harmonics and Torque Ripples

This paper proposes an improved methodology to minimize the cogging torque, harmonics and torque ripples in Brushless DC (BLDC) motor. First off, the cogging torque is reduced by designing the BLDC motor with bifurcated active surface area using Finite Element Analysis (FEA). The harmonics and torque ripple is minimized using PI and Fuzzy controllers. These controllers are analyzed to bring out an optimal solution. The effectiveness and flexibility of the individual techniques of proposed control method is verified through simulations [Matlab Simulink].

Comparison of Fuzzy and FPGA Based Fault Tolerant Schemes for Four Switch Space Vector PWM Inverters

This paper presents a comparison of fuzzy logic controller (FLC) and FPGA based fault tolerant scheme for four switch voltage source inverter (VSI). The proposed fault tolerant VSI accommodates only four switches in two legs instead of six switches in three legs, two switches in auxiliary leg and two triac switches . The cost, electromagnetic interference (EMI) and switching losses are reduced due to absence of two switches in four switch inverter. In this paper fault tolerant control of the above two methods are designed to detect and isolate the fault which occurs in any one of the switches in the inverter. The merit of this system is to minimize the time between the fault occurrence and its isolation. In all methods, respective controllers generate necessary gate pulses for the power switches to drive three phase induction motor. In comparison, the modeling and simulation results show that the FPGA based scheme is found to be better dynamic characteristics, less switching losses and better fault recovery time of below 50ns

Numerical Simulation of Hot Isostatic Pressing Process for the Manufacture of Parts Used in Biomechanics

This study is devoted to numerical modeling and simulation of the process of forming of metal powders by hot isostatic compaction (HIC) for the production of parts in biomechanics. A continuous model based on a visco plastic law is used to describe the process of densification HIP (hot isostatic pressing). The model was implemented in a finite element code developed under the platform FORTRAN POWER STATION. For numerical simulation, we considered a cylindrical die subjected to isostatic pressure and a temperature field. We study variations of different parameters: relative density and radial shrinkage. To validate the numerical model, the results are compared with experimental data.

Modelling and Simulation of Methanation Catalytic Reactor for Renewable Electricity Storage

Storing renewable electricity in a natural gas grid is an innovative concept. Renewable energy (wind or solar power) is stored as chemical energy in existing storage capacities, which is an advantage over hydrogen. Storage and power conversion technologies for natural gas are state-of-the-art, commercial technologies unlike hydrogen. A further advantage of storage is the higher energy density of methane. Renewable natural gas substitute (SNG) can be stored, distributed and reconverted on demand in balance power. In this novel approach, renewable energies are converted via reversible solid oxide cells (RSOC) into CO and Hydrogen. Syngas (H2 and CO) is then converted into methane. Thus, the main conversion step is methanation. Methanation synthesis is a catalytic exothermal process at temperatures of 473-673 K and high pressure from 20 to 70 bar. Syngas enters the methanation reactor with H2/CO molar ratio of 3. The reactions considered in the proposed model are CO methanation and Water Gas Shift conversion (WGS). Modelling and simulation of the methanation catalytic reactor was developed using the Aspen Plus™ software considering an isothermal fixed bed reactor with steam recovery and CO methanation kinetic on Ni catalyst. The model was validated by comparing the calculated gas concentration profiles (CH4, CO, CO2 and H2) with the recent experimental data obtained on bench-scale and with industrial data. The mean absolute percentage error was 12 %. The mixture leaving methanation reactor contained 47.3 % of CH4, 1.2 % of H2, 6.6 % of CO2, 0.1 % of CO and 44.7 % of H2O.

Assessment of Carbon Capture Options for Super-Critical Coal-based Power Plants

Power generation is one of the industrial sectors with major contribution to greenhouse gas emissions. For climate change mitigation, a special attention is given to the reduction of CO2 emissions by applying capture and storage techniques in which CO2 is captured and then stored in suitable safe geologic locations. Carbon capture and storage (CCS) technologies are expected to play a significant role in the coming decades for curbing greenhouse gas emissions and to ensure a sustainable development of power generation and other energy-intensive industrial sectors (e.g. cement, metallurgy, petro-chemical etc.). This paper evaluates super-critical coal-based power plants with and without carbon capture. The analysis is geared toward quantification of main plant performance indicators such as: fuel consumption, gross and net energy efficiency, ancillary energy consumption, carbon capture rate, specific CO2 emissions, capital costs, specific capital investments and operational costs etc. For CCS configurations, two post-combustion CO2 capture options were considered. The first option is based gas-liquid absorption using a chemical solvent (methyl-diethanol-amine – MDEA etc.). The second option is based on calcium looping cycle, in which the carbonation/calcination sequence of CaO/CaCO3 system is used for carbon capture. The power plant case studies investigated in the paper produces around 950 – 1,100 MW net power with at least 90 % carbon capture rate. The mathematical modelling and simulation of the whole power generation schemes will produce the input data for quantitative techno-economic and environmental evaluations of power plants with carbon capture (similar power plant concept without CCS was used as reference for comparison). Mass and energy integration tools were used to assess the integration aspects of evaluated carbon capture options in the whole power plant design, to optimise the overall energy efficiency and to evaluate the main sources of energy penalty for CCS designs.

Modeling and Simulation of Non-Newtonian Fluid MoldFilling Process with Phase Change

A gas-liquid two-phase model for the simulation of a power-law fluid mold filling process with the consideration of phase change is proposed, in which the governing equations for the melt and air in the cavity, including the mass conservation, momentum conservation and energy conservation equations, are unified into one system of equation. A revised Enthalpy method, which can be used for both the melt and air in the mold cavity, is proposed to describe the phase change during the mold filling. Finite volume method on non-staggered grid is used to solve the system. The level set method is used to capture the interface evolution during the mold filling process. The interface evolution and the distributions of physical quantities such as velocity, pressure and temperature and so on are given. The “frozen skin” layers under different temperature and velocities conditions are discussed in detail. Numerical results show that increasing the temperatures of the melt and cavity is a better way to get rid of the “frozen skin” layer than increasing the injection velocity.

Modelling and Simulation of Artificial Neural Network Based Harmonic Elimination Technique for Solar-Fed Cascaded Multilevel Inverter

This paper presents the harmonic elimination technique for a fifteen level cascaded multilevel inverter (CMLI) supplied with the seven varying DC input sources. Here, the input supply sources are obtained from the solar Photovoltaic’s (PV). The harmonic equations are solved and switching angles are obtained in such a way that the fundamental is kept constant and lower order harmonics are minimized or eliminated. The data set with varying input DC voltages and switching angles are trained with Artificial Neural Network (ANN). This trained network is integrated with CMLI to improve the power quality. The modeling of solar panel which serves as the input to the CMLI is developed. A eleven level CMLI with five varying DC input sources and a set of multiple carrier Pulse Width Modulation (PWM) methods are also given for comparison. The results show that ANN based method provides a significant improvement with respect to the reduction of Total Harmonic Distortion (THD).

Trend of the Research on Public Funded Projects

As one of the main means to deliver service, Public Funded Projects (PFPs) always play a vital part in the development of the human society. Accordingly, research interests concerning PFPs from the construction industry have led to a great number of published papers during the past decades. Aimed at identifying the emerging research trend of researches addressing PFP issues, this study obtained target publications from selected international journals, and analyzed those articles in terms of the number of annual publications, authors and affiliations as main contributors, popular research themes, and preferred research methods. This study indicated that the number of PFP articles have been increasing, which could imply the growing importance of PFPs to the construction industry at large. What is more, the findings suggest that researchers from the United States are the most active in this discipline, followed by those from the United Kingdom, Australia, China, Hong Kong and Spain. And the origins of productive affiliations follow a similar way. With respect to emerging hot research topic, integration research, delivery method, sustainable exploration, governance issue, financial concern, performance study, risk management and decision-making challenges tend to attract more concerns of researchers within this discipline. Meanwhile, it was also found that the target articles of this study can be catalogued into three groups, field report, theoretical analysis, and quantitative calculation respectively. In addition, more vigorous modeling and simulation techniques such as stochastic frontier regression modeling and fuzzy synthetic evaluation simulation have been adopted in related researches. Moreover, investigations of content analysis also exhibit that sustainability should be the essential characteristic of PFPs, but there is still a long way to go concerning current sustainability performance of most PFPs. More relative research efforts are needed to ensure a sustainable development of PFPs as well as the construction industry.

Modeling and Simulation of an Emulsion Copolymerization Process

Modeling and Simulation of an Emulsion Copolymerization Process

QMAEA: A quantum multi-agent evolutionary algorithm for multi-objective combinatorial optimization

Multi-objective combinatorial optimization (MOCO) is an essential concern for the implementation of large-scale distributed modeling and simulation (MS) system. It is more complex than general computing systems, with higher dynamics and stricter demands on real-time performance. The quality and speed of the optimal decision directly decides the efficiency of the simulation. However, few works have been carried out for multi-objective combinatorial optimization MOCO especially in large-scale and service-oriented distributed simulation systems (SoDSSs). The existing algorithms for MOCO in SoDSSs are far from enough owing to their low accuracy or long decision time. To overcome this bottleneck, in this paper, a quantum multi-agent evolutionary algorithm (QMAEA), for addressing MOCO in large-scale SoDSSs is proposed. In QMAEA, the concept and characteristics of agent and quantum encoding are introduced for high intelligent searching. Each agent represented by a quantum bit, called a quantum agent (QAgent), is defined as a candidate solution for a MOCO problem, and each QAgent is assigned an energy, which denotes the fitness or objective function value of the candidate solution represented by it. Each QAgent is connected by four other QAgents nearby, and all QAgents are organized by an annular grid, called a multi-agent grid (MAG). In a MAG system, the population of QAgents can reproduce, perish, compete for survival, observe and communicate with the environment, and make all their decisions autonomously. Several operators, i.e. energy-evaluation-operator, competition-operator, crossover-operator, mutation-operator and trimming-operator, are designed to specify the evolvement of the MAG. The theory of predatory search strategy of animals is introduced in the evolution of QMAEA. Multiple evolutionary strategies, such as local-evolution-strategy, local-mutation-strategy and global-mutation-strategy are designed and used to balance the exploration (global search ability) and the exploitation (local search ability) of QMAEA. The framework and procedures of QMAEA are presented in detail. The simulation and comparison results demonstrate the proposed method is very effective and efficient for addressing MOCO in SoDSSs.

Cost-effectiveness analysis on the once-in-a-lifetime cervical cancer screening program for women living in rural and urban areas of China

To estimate the cost-effectiveness of once-in-a-lifetime cervical cancer screening program and to predict the optimal modality for its operation on women living in rural and urban areas of China, based on Markov modeling and simulation. Three modalities including visual inspection with acetic acid plus Lugol's iodine (VIA/VILI), conventional Pap Smear (Pap Smear), and simple HPV DNA testing (careHPV) were hypothesized for the rural cohort, whereas other five modalities including Pap Smear, liquid-based cytology (LBC), simple HPV DNA testing (careHPV), Hybrid Capture 2 HPV DNA testing (HC2), and LBC plus HC2 (LBC + HC2) were tested for the urban cohort. A Markov model was constructed based on the factors as natural history, screening, diagnosis and treatment on cervical cancer using data related to the epidemics and the costs from rural and urban areas of the country. Long-term effectiveness and cost-effectiveness were predicted through simulation of the model. Compared to the non-screening scenario, the amount of life years saved were 277.97 - 2727.53 and 134.02 - 1446.84 years per 100 000 women, respectively, for different cohorts in rural and urban areas. The cost-effectiveness ratios were 1520.99 - 2453.74 and 3847.35 - 44 570.35 RMB per life year saved, respectively, for different cohorts in rural and urban areas. The incremental cost-effective ratio for careHPV starting from 40 years old (careHPV@40) and careHPV from 30 years old (careHPV@30) dominated other strategies for the rural cohort, while careHPV@40, careHPV@30, HC2 from 30 years old (HC2@30), and LBC + HC2 from 30 years old (LBC + HC2@30) were dominant for the urban cohort. All eight once-in-a-lifetime cervical cancer screening modalities were cost-effective based on our model. In particular, careHPV screening starting from 40 years old seemed to be the most cost-effective one for women living in both rural and urban areas.

Simulation and analysis of second-harmonic signal based on tunable diode laser absorption spectroscopy

Tunable diode laser absorption spectroscopy (TDLAS) is a new gas detection technique developed recently with high spectral resolution, high sensitivity and fast time response. The second-harmonic signal of wavelength modulation spectroscopy (WMS) is often used as the detection signal for gas concentration inversion. Using Simulink, a visual modeling and simulation platform, the authors simulated the WMS signal based on TDLAS, and got the second-harmonic signal by using lock-in amplifier algorithm. Digital orthogonal algorithm was studied in this paper. The relationship between second-harmonic signals and the modulation indexes was analyzed by comparing changes of second-harmonic under different modulation indexes, in order to find out the optimized parameters for second-harmonic detection.

Modeling and Simulation of FACTS Devices in Large Power System

In this paper steady-state modeling of Thyristor Controlled Series Compensator (TCSC) for power flow studies has been represented and discussed in details. In same manner firing angle model for TCSC is used to control active power flow of the line to which TCSC is installed. The proposed models take firing angle as state variable in power flow formulation. To validate the effectiveness of the proposed models Newton-Raphson method algorithm was developed to solve power flow equations in presence of TCSC. Case studies are carried out on 68-bus (western Algeria) system to demonstrate the performance of the proposed models.

Modeling and simulation to predict partial deposition of ammonia and specific growth rate of bacterial in homogeneous formation in Obio/Akpor, rivers state of Nigeria

Specific growth rate of bacteria has been expressed through characteristics influence deposition at various stratums to aquiferous zone. The growth rates of bacteria are under the influence of the substrate utilization that contaminates groundwater aquifers in various formations. Derived mathematical equations generated theoretical values that expressed the rate of exponential phase of ammonia deposition and bacteria growth rate in homogenous formation. Slight fluctuations were experienced in between the aquiferous zones under the influence of variation from degree of porosity and permeability of the stratum. Experimental values were compared with the theoretical values; both parameters produced a best fit. These expressed the application of the derived model that determines partial deposition of ammonia and bacteria growth rate in homogenous formation. The study is imperative because the model expressed partial depositions of ammonia that determine the growth rate of bacteria at various formations to groundwater aquifers in the study area.

Modeling and simulation of fungi transport in waste dump site in Obioakpor, rivers Stater of Nigeria

Modeling and simulation of fungi transport in waste dump site has been evaluated. Mathematical model were developed considering all the variables in the system that influence transport process of fungi to ground water aquifers. Geologic history was found to influence the fast transport of fungi as presented in the figure. More so rapid increase of microbial growth were found to be influenced by porosity and permeability of the soil, geomorphology and geochemistry of the strategraphic were found insignificant on the transport process, these were experienced on high rate of microbial increase or growth as presented in the figure, the present of inhibitors (heavy metals) were also found to be insignificant, the study recommend that the derived model should be thoroughly apply to improve ground water quality in the study location.

New Adsorption Air Conditioning System Powered by Solar Energy; Operation Principals and Winter Mode Modelling and Simulation

This research focuses on the development of new adsorption air conditioning system powered by solar energy. The new system uses humidifier, heat exchanger, rotary desiccant and silica gel/water adsorption chiller. This unit is introduced to allow the production heat or cold with a good indoor air quality, and controls hygrometry. This system is powered by solar energy and does not “abuse” nature. The new design is made of five sections which are: the Pre-cooling / pre-heating, the drying, the energy recovery, the water adsorption chiller and the brewing. It permits three working modes according to the climatic conditions and to the season of the year. This work focuses on the design, modelling and numerical simulation of the air conditioning system working in winter mode. The simulation uses ambient temperature and solar flux for Gafsa city conditions to predict the behaviour of the system. Moreover, we present the evolution temperature during 24 hours in the building, the storage tank and at some point on the new system. This work includes a study of the building relative humidity, vs respectively, relative humidity at the outlet air of the humidifier and temperature of the water used for humidification

Three Phase 5-Level PWM Inverter for Grid Connected Photovoltaic System

Multilevel inverter topologies are increasingly being used in medium and high power applications due to their many advantages such as low power dissipation on power switches, low harmonic contents and low electromagnetic interference (EMI) outputs. Also they enable the use of renewable energy sources, such as photovoltaic, wind, and fuel cells. This paper presents Modeling and simulation of three phase five-level neutral clamped (NPC) PWM inverter for grid connected PV system. The proposed system fundamentally consists of PV array, a DC/DC converter, a DC/AC inverter and LCL filter connected to the grid through three phase transformer. To track the maximum power point, Perturb and Observe (P&O) method is used. The Performance and validity of the system is verified through MATLAB/Simulink and the results are compared with a three-level neutral clamped (NPC) PWM inverter in terms of THD.

Modelling and Simulation of MEMS Electret Vibration-Driven Energy Harvesters

To solve the problem of feeding the remote microsystems the electret microgenerators powering by the energy of ambient micro vibrations were analyzed. The numerical modeling of all the operation modes of these generators was performed not taking into account the certain design of mechanical part of their operation. This approach allows one to analyze generator operation in the full range of possible parameters, such as generation frequency, load, capacitance modulation depth and electret polarization value. The cases of out-of-plane vibrations as well as the lateral (in-plane) shift of the capacitor plates were investigated. Basing on the results of numerical modeling of all the operation modes of electret generators the analytical expressions for maximum generated power were derived. The performed analysis has shown that for the range of low frequency vibrations (10-100 Hz) the power density could be increased by two orders of magnitude compared with known prototypes

Modelling and Simulation of Tilting Vehicles

Modelling and Simulation of Tilting Vehicles