Search

Paper is a stochastic network of fibres, water and additives, and in that sense it may be envisaged as a composite material. Since fibres are much longer than the thickness of the paper sheet, the network is planar and almost two-dimensional. The two-dimensional structure governs many paper properties but the three-dimensional porous structure is also important. Insight into the structural changes that take place when paper is compressed in the paper machine may be gained by modelling and simulation of its viscoelastoplastic behaviour. The present work describes a mathematical model based on the cellular solids theory, characterising the nonlinear rheologic behaviour of the material. This approach results in an unsteady state problem and the resulting set of ODEs is solved by means of the DLSODES subroutine, which uses an integrator based in the Gear method. Experiments were conducted on a laboratory-scale dynamic press in order to validate the mechanical model. [Copyright &y& Elsevier]

A. V. Hill's 1938 paper ‘The heat of shortening and the dynamic constants of muscle’ is an enduring classic, presenting detailed methods, meticulous experiments, and the model of muscle contraction that now bears Hill's name. Pairing a simulation based on Hill's model with a reading of his paper allows students to follow his thought process to discover key principles of muscle physiology and gain insight into how to develop quantitative models of physiological processes. In this article, the experience of the author using this approach in a graduate biomedical engineering course is outlined, along with suggestions for adapting this approach to other audiences. [ABSTRACT FROM AUTHOR]

There are few of transient control models are adapted to asynchronous induction coil launcher (AICL) with air core coil. Thus, many papers about AICL were written with the goal of increasing muzzle velocity of projectile. This paper concentrate on how to control the projectile speed and thrust accurately by using improved current filament (CF) method and variable voltage variable frequency (VVVF) scheme. The improved CF method contains mathematical model of three-phase inverter based on switch function, including conventional two level converter and cascaded multilevel converter models. The whole launch process is programmed with MATLAB. Simulation results show that this scheme have a smoother thrust fluctuation on projectile than other driving models. The motor parameters are changing with the temperature and frequency in launching process. Hence, the constant voltage frequency ratio (V/f) in this paper is more simple and reliable than vector control. To verify the control model and simulation results, a nine stages coil launcher prototype is constructed. The measured force and muzzle velocity are basically consistent with simulation results. It is proved that the improved CF method and VVVF strategy is feasible, and it is characterized by its small calculating amount that make it a valuable tool for design of AICL. The simple and excellent control of the thrust during launch process avoids load peaks, which means that the payload is handled more carefully compared to the classical launchers. [ABSTRACT FROM PUBLISHER]

Line-commutated converters are extensively used as the interface between ac grids and classic HVDC systems. At the inverter side, commutation failure of switches is one of the most common faults that can pose threats to the system operation. Practical and reliable study of such phenomena relies on accurate and efficient converter models for simulations. Recently, a parametric average-value model (PAVM) has been presented for ac–dc rectifiers, which considers the internal faults of the converter. In this paper, the PAVM methodology is extended to the dc–ac inverter systems, including the commutation failure of switches. The proposed PAVM also augments an automatic fault detection technique to determine the faulty switches. Using comprehensive simulation studies, the developed model is verified to accurately predict the commutation failure of switches and reconstruct the waveforms consistent with the detailed switching models of inverters while being computationally more efficient. The proposed PAVM is envisioned to be an efficient and accurate asset for simulation of HVDC systems and inevitable when faults of switches need to be considered. [ABSTRACT FROM AUTHOR]

This paper deals with the problematic of the drive system of small-diameter knitting machines (hereinafter "knitting machines"). An alternative design of a new drive system is presented that addresses the effective working position of selected operating elements, i.e., a cylinder, a dial, and a roller cutter. The design is protected by patent No. 303578, and the authors of this paper also authored the patent. For the description and simulation of the drive system, mathematical models have been elaborated of the existing and new drive system, which include an additional design of a more suitable stroke for the movement of the cylinder. The output of the simulations are the courses of kinematic quantities, torque, and electric current, elucidating the benefits of the new drive system. Based on the structure of the new drive system, a test device has been designed and manufactured to verify functionality and reliability. The new drive system consumes less energy, simplifies the machine frame and reduces noise emissions. The obtained results can help in researching the issue of knitting machine frames, and in addition, the new system brings new technological possibilities for knitting. [ABSTRACT FROM AUTHOR]

This paper presents the simulation and mathematical models necessary for studying the behavior of the pneumatic cylinders in static and dynamic conditions. The mathematical models are simplified, accessible and adaptable to different applications; they can be used in the design phases of new pneumatic units in the industrial fields. The models for cylinders with or without braking at travel end are presented. Depending on each system, these models can be supplemented with models of equipment for regulation and distribution, in order to study the respective systems. The proposed models try to take into consideration the particularities of the pneumatic systems: compressible working environment, maximum working pressure limited to 10 bar at the most, specific damping effects, etc. [ABSTRACT FROM AUTHOR]

The paper deal with a mathematical model of a pneumatic system and simulation of its behaviour. In the Matlab-Simulink Simscape program, there are models of basic elements from which it is possible to build a model of the entire system. The article describes the gradual testing of pneumatic elements mathematical models on the base of comparison with experimental data. [ABSTRACT FROM AUTHOR]

For the past twenty years, there has been increasing interest and investment in solar photovoltaic (PV) technology. One particular area of interest is the development of concentrating PV (CPV), especially for use in building integration. Many CPV designs have been developed and investigated. This paper aims at producing a mathematical modelling using MATLAB programme to predict the current-voltage (I-V) and power-voltage (P-V) characteristics of a static CPV. The MATLAB programme could also simulate the angular response of the CPV designs-which has never been explored in the previous literature. In this paper, a CPV known as the rotationally asymmetrical dielectric totally internally reflecting concentrator (RADTIRC) was analysed. A specific RADTIRC design that has an acceptance angle of ±40° was investigated in this paper. A mathematical modelling was used to simulate the angular characteristics of the RADTIRC from −50° to 50° with an increment 5°. For any CPV, we propose that the value of opto-electronic gain, Copto-e needs to be included in the mathematical model, which were obtained from experiments. The range of incident angle (±50°) was selected to demonstrate that the RADTIRC is capable of capturing the sun rays within its acceptance angle of ±40°. In each simulation, the I-V and P-V characteristics were produced, and the short circuit current (Isc), the open-circuit voltage (Voc), the maximum power (Pmax), the fill factor (FF) and the opto-electronic gain (Copto-e) were determined and recorded. The results from the simulations were validated via experiments. It was found that the simulation model is able to predict the I-V and P-V characteristics of the RADTIRC as well as its angular response, with the highest error recorded for the Isc, Voc, Pmax, FF and Copto-e was 2.1229%, 5.3913%, 9.9681%, 4.4231% and 0.0000% respectively when compared with the experiment. [ABSTRACT FROM AUTHOR]

Abstract: This paper concerns the modelling of an accumulator used in industrial elastic web processing plant such as paper mills, fabric, rolling mills etc. Accumulators are used to allow rewind or unwind core changes while the process continues at a constant web velocity. A new nonlinear model of a pneumatic actuated industrial accumulator including pneumatic jack model, static friction representation and web weight is first detailed which enables to deduce a linear model. These models are derived from physical laws that describe web tension and velocity dynamics in each web span. In a second part, the effects of time-varying mechanical parameters, such as web Young modulus, web length and rollers inertia on accumulator dynamics are presented. The performances of the modeled accumulator are illustrated by simulations in Matlab/Simulink software environment. [Copyright &y& Elsevier]

The purpose of this paper is to achieve mathematical model and simulation network for a normally closed valve type DBD sold by Rexroth. The model developed, validated experimentally, was introduced in library simulation models developed by the authors with AMESIM program. Among the other simulation models developed and validated experimentally in the laboratory by the authors, this model finds its usefulness in rapid construction and simulation of complex networks to drive and control hydraulic systems. [ABSTRACT FROM AUTHOR]

In view of the defects of simulation modelling and resource optimization algorithm for small-batch multi-variety job-shops, this paper presents a mathematical model and simulation model which considers the dual resources optimization of both manpower and equipment to minimize the investment in the overall job-shop under the condition of satisfying the requirement of average productivity and average production cycle. The mathematical model established simplifies the solving process of traditional optimization algorithm and replaces the optimal solution of the original problem with the obtained approximate solution. The job-shop dual resource optimization simulation system model is constructed to verify the mathematical model proposed. The simulation results verify the effectiveness of the results of the mathematical model. This paper also designs the multi-agent system and the dual resources optimization-based job-shop entity flow. The simulation results show that when the job-shop workers and processing equipment are within a certain range, the appropriate increase of the buffer zone in the equipment room can effectively enlarge the system's capacity. With the further rise of the buffer zone number, the system's capacity will no longer increase. Under the ideal scheduling strategy, the utilization ratio of equipment and labour efficiency can reach the maximum value. [ABSTRACT FROM AUTHOR]

In the present paper, several mathematical models of lifts' systems with various control rules are constructed and simulated data are used for estimating the various parameters of the systems. For systems with a rare input flow of customers, the graphs, describing the positions of the lifts, at the preceding customer's arrival instant, are given. These graphs help analytically find, the various characteristics of the lifts' systems (a customer's average waiting time, a customer's total time, energy expenses and others). There are introduced the various control rules by the lift systems, which are investigated by simulation. Using Wolfram Mathematica, the authors have prepared several programs for simulating and estimating the various operational parameters of the lifts' systems with different control rules. Using these programs, the numerical estimates of the various parameters the considered lifts' systems, have been found. These data can be used for defining the dependence of optimal lift roominess on an intensity of input customers' flow and finding the optimal number of the lifts, during planning and construction of the buildings and skyscrapers. [ABSTRACT FROM AUTHOR]

Variable compression ratio (VCR) technology has long been recognized as a method for improving the engine performance, efficiency, and fuel economy of automobiles, with reduced emissions. In this paper, a novel hydraulic continuous VCR system based on the principle of an adjustable hydraulic volume is introduced. The continuous variable compression ratio of the VCR system is realized by the hydraulic system controlling the rotation of the eccentric pin to change the positions of the top dead center (TDC) and the bottom dead center (BDC). The construction of the mathematical model and simulation model of the VCR system is also presented in this paper. The piston motion characteristics, flow characteristics, and pressure characteristics of the hydraulic system of the VCR system at different engine speeds and adjustment quantities are studied by simulation in this paper. The simulation results show that the VCR system has a fast response and good dynamic characteristics, and can achieve continuous adjustment of the compression ratio. [ABSTRACT FROM AUTHOR]

The modeling of cutting forces plays an important role in the progress of research and technology in most machining processes. In particular, peripheral milling is a cutting process difficult to model due to the large number of variables involved. Among these variables, tool runout affects process performance by modifying milling force patterns, shortening the tool life and machine components, and by degrading workpiece quality. In this paper, a methodology to evaluate tool runout in peripheral milling is presented. The use of a boring toolholder is proposed to make controllable changes in the tool offset that modifies tool runout. In addition, the proposed methodology has been validated by means of a piezoactuator-based system that allows tool runout compensation through controlling workpiece displacement. Experimental and simulated results presented in this paper reveal the practical applications of this methodology for researchers and engineers involved in the practice of milling and its modeling. [ABSTRACT FROM AUTHOR]

This paper presents a new solution method that combines state-space and nodal analysis for the simulation of electrical systems. The presented flexible clustering of state-space-described electrical subsystems into a nodal method offers several advantages for the efficient solution of switched networks, nonlinear functions, and for interfacing with nodal model equations. This paper extends the concept of discrete companion branch equivalent of the nodal approach to state-space described systems and enables natural coupling between them. The presented solution method is simultaneous and enables benefitting from the advantages of two different modeling approaches normally exclusive from one another. [ABSTRACT FROM AUTHOR]

Dynamic Travelling Salesman Problem (DTSP) is a novel type of TSP where the number of cities in the problem domain changes unpredictably. The approaches to handling dynamism in those DTSPs, has been solving the problems as they were static and recreating the models after each change. In this respect, multi-agent based strategies along with intelligent approaches provide an opportunity to deal with those difficulties. The proposed approach in this paper is based on the modification of existing solutions according to changes in the city domain. Thereby problem is not resolved while local city agents deliver their novel bids (solution proposals) for these new conditions. Finally, general manager agent makes a decision about the new solution. This study presents two different agent-based solution strategies for providing promising solutions to DTSP. One of these strategies is based on the competition of city agents in a greedy way and thereby city agents just search for randomly selected alternatives which are feasible for the new conditions. The second strategy covers competition of city agents by the use of great deluge algorithm as the search mechanism. Finally, both of those proposed strategies are compared against the solutions of reinvented models. Agent-based strategies start to produce better results as the problem size increases. [ABSTRACT FROM AUTHOR]

Demand Side Management techniques facilitate in obtaining cost effective solutions to handle peak load scenarios by deferring installation of additional power generation. The hourly temperature profiles, particularly for temperature sensitive devices of residential load become important to estimate the load demand. In this paper, a mathematical model is developed to generate the hourly temperature profiles considering data based on maximum average, minimum average and average temperatures for all months in a year. Simulation code is developed using MATLAB and the results are in close agreement with the measured data of Oman. The model developed is a generic in nature and may be used for any location. The role of temperature sensitive devices becomes implicit when correlation between temperature and load are plotted. The viable demand side management strategies are discussed in paper to reduce the electricity demand. [ABSTRACT FROM AUTHOR]

This paper presents a generic discrete model for the moving, intelligent target problem. Our objective is to maximise the probability of detection of the moving target with respect to target and searcher’s constraints. The solution method proposed here is composed on two stages. The first one aims at providing a large-scale strategy by solving an Integer Linear Program approach. As a direct solution of this problem is not practically possible, we use a decomposition of the problem into a searcher’s strategy on one side, and the target’s strategy on the other side. A good strategy for the searcher is determined using a sliding window procedure. Concerning the target, our approach consists in simulating some of the target’s possible strategies and considering each of these possibilities as an independent and deterministic entity. The second stage is dedicated to adjusting the large-scale strategy provided by stage 1. Finally, numerical results are presented so as to assess the impact of our approach. [ABSTRACT FROM PUBLISHER]

This paper introduces the characteristics of group-distributed manufacturing mode, and makes some basic assumptions, including scheduling principle and scheduling cycle, etc. On this basis, a co-scheduling model of group distributed manufacturing system is built, and simulation algorithm based on heuristic rules is compiled. Then we make a simulation research on the co-scheduling model through MATLAB. Simulation results show that production cost and production load balance are both optimized distinctly by using the co-scheduling model, which confirms that the co-scheduling model of group distributed manufacturing system is scientific and effective. [ABSTRACT FROM AUTHOR]

The paper is focus on usage of simulating technologies in construction of combat and special vehicles. Simulating technologies are widely spread in all of spheres of industry. These technologies offer a lot of advantages -- e.g. evaluation of various vehicle configurations, simulation of various critical states of vehicle, comparison of vehicles in the same surrounding. This manner is suitable for vehicle evaluation, too. Paper consists of introduction, mathematic model description, terrain -- obstacle description and simulation. [ABSTRACT FROM AUTHOR]

Copyright of Technical Transactions / Czasopismo Techniczne is the property of Sciendo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Model checking is a formal method for verifying whether the system satisfies a user-defined specification. Compared to simulation, model checking is restricted in capacity. On the other hand, simulation is weak in detecting bugs that require long and complex sequences of events to be exposed. This paper combines model checking and simulation in an abstraction-refinement scheme to mitigate the problems of both methods. Abstraction refinement iteratively constructs a simplified model to verify the original model. While a simplified model mitigates the weakness of model checking, the set of simplified error traces model helps guide simulation toward deep bugs. In abstraction refinement, concretization—a process of deriving an error trace in the original model from the abstract ones—is used to invalidate spurious abstract error traces or to refute a property. In this paper, we describe a novel concretization algorithm that combines simulation with satisfiability to efficiently refute properties with very long error traces. [ABSTRACT FROM AUTHOR]

This paper focuses on a lot merging–splitting problem in a semiconductor wafer fabrication facility in which a relatively large number of wafer types are produced according to orders with different due dates. In the fab, two or more lots can be merged into a single lot if routes and all processing conditions of the lots are the same for a number of subsequent operations, and the merged lot is split into the original lots at the point where the routes or processing conditions become different. We suggest lot merging–splitting algorithms to reduce the total tardiness of the orders and the cycle times of the lots. The suggested algorithms are evaluated through a series of simulation experiments and the result shows that the algorithms work better than a method used in a real fab. [ABSTRACT FROM PUBLISHER]

This paper suggests a pedagogical approach to teaching the subject of behavioral modeling of switch-mode power electronics systems through simulation by general-purpose electronic circuit simulators. The methodology is oriented toward electrical engineering (EE) students at the undergraduate level, enrolled in courses such as “Power Electronics,” “Industrial Electronics,” or the like. The proposed approach is demonstrated by simulation example of a realistic active power factor corrector (APFC) system. The paper discusses the derivation of PSPICE/ORCAD-compatible behavioral models, their software implementation, and fast time domain, frequency domain, and stability analysis simulation techniques suitable for virtual study of complex nonlinear feedback systems. Some “tricks of the trade” are also suggested. The paper can be helpful to instructors of a “Virtual Power Electronics Laboratory” course wanting to conduct a software experiment on a PFC system. [ABSTRACT FROM AUTHOR]

The paper specifies an Integrated System (IS) devoted to the management of Intermodal Transportation Networks (ITNs) to take both tactical decisions, i.e., in an offline mode, and operational decisions, i.e., in real-time. Both the resulting IS structures rely on a closed-loop approach that is able to tune the choices with the current system conditions. In either case, the core of the presented IS are a reference model and a simulation module. In particular, the reference model uses information from the real system, obtained by modern Information and Communication Technologies (ICTs) and the simulation module evaluates the impact of the management decisions. In order to obtain a systematic model suitable to describe a generic ITN, the paper proposes a metamodeling approach that describes in a thorough and detailed way the structure and the behavior of ITNs. Moreover, the metamodeling procedure is a top-down technique based on the well-known Unified Modeling Language (UML), a graphic and textual formalism able to describe systems from structural and behavioral viewpoints. In order to show the IS application at the tactical decision level, the paper specifies the IS for an ITN case study that is constituted by the port of Trieste (Italy) and the inland terminal of Gorizia (Italy). The results show how the IS can improve the performance of the ITN by applying ICT tools and information-based services. [ABSTRACT FROM PUBLISHER]

This paper presents the evaluation of the performance, in terms of uncertainty, of a tool designed to estimate the main parameters of a model of a photovoltaic panel (PVP) under real and/or simulated working conditions. The presented tool permits the characterization of the panel, and it is useful to predict its behavior in whatever working condition; in this way, it is possible to compare the actual and expected performance to prevent any decrease in the output power, so permitting the replacement of the monitored module before it goes out of order or its efficiency falls under a given threshold. The well-known two-diode model is used to estimate the parameters of the electrical equivalent circuit of the PVP and to simulate the I–V and P–V characteristic curves in any given environmental condition of irradiance and/or temperature. The model and the estimation algorithm are implemented with MATLAB functions, whereas data acquisition and result presentation are managed by a LabVIEW graphics user interface. The presented tool has been validated against an experimentally characterized PVP. The environmental parameters of the model such as irradiance and temperature have been set (with their respective uncertainties) during simulations or directly measured during the outdoor tests, whereas the others parameters have been evaluated using a best-fit algorithm on the measured data. The estimation is based on the minimization of a new objective function and on a modified expression of the model resistances, which differ from those mentioned in the available literature. After a review of the state of the art, this paper provides the description of the estimation technique and its validation by means of simulations and experiments. Some results are also provided to illustrate the performance of the proposed test method. [ABSTRACT FROM AUTHOR]

Cellular Automata (CA), as they are presented in the literature, are abstract mathematical models of computation. In this paper we present an alternate approach: using the CA as a model or theory of physical systems and devices. While this approach abstracts away all details of the underlying physical system, it remains faithful to the fact that there is an underlying physical reality which it describes. This imposes certain restrictions on the types of computations a CA can physically carry out, and the resources it needs to do so. In this paper we explore these and other consequences of our reformalization. [ABSTRACT FROM AUTHOR]

Purpose - One of the main challenges facing construction contractors is incorporating future unknown contracts into their annual financial budgets. This paper sets out to review current academic work in this area and to argue that computer-based simulation techniques are too complex to be adopted in the industry. Therefore, an alternative and a mathematically-based technique needs to be developed and evaluated. Design/methodology/approach - The paper proposes that, as the pattern of winning construction contracts lacks any seasonality, it may be possible to assume all future work to be starting at one point in time and, by using an average standard value build-up curve, average duration and the total value work needed, contractors will be able to estimate the total value of contracts needed to achieve a target turnover. Based on the total value of contracts to be won, a proposed mathematical equation is then used to assess the levels of working capital requirements. Findings - The paper evaluates the proposed mathematical model through a series of hypothetical scenarios (developed using a detailed and tested computer-based simulation model). Results demonstrated the validity and reliability of the models. Research limitations/implications - The working capital element of the proposed model applies to construction projects where traditional payment mechanisms have been applied (interim payments based on measurements). Practical implications - The model is very practical in nature and will allow construction companies (particularly large ones) to assess the level of work (in terms of number and values of contracts) they will need to win for them to meet targets for turnover. The model also allows contractors to assess the associated level of funding required. Originality/value - The mathematical model developed allows contractors to incorporate into their budgets future unknown contracts without the need for computer simulation. [ABSTRACT FROM AUTHOR]

Because of the complexity of controlling the flexible manufacture system in welding, a theory of Petri net is adopted to model and simulate in this paper. When we model the complex system, a new way named TCPN is used to analyze information. And two kinds of models are built which are STCPN and MTCPN on the two systems, single welding robot system and multi welding robot system, respectively. After building and analyzing the control models, an optimization algorithm named full rank is designed to optimize and consummate the models, which is proved right in theory by simulation software cpntools. The result of the simulation experiment illustrates that the way of the model is rational and feasible. [ABSTRACT FROM AUTHOR]

The paper presents analytical and simulation models to study the impact of interrupt overhead on operating system throughput of network elements such as PC-based routers, servers, and hosts when subjected to high-speed network traffic. Under such high network traffic, the system throughput will be negatively affected due to interrupt overhead caused by the incoming traffic. We first present an analytical model for the ideal system when interrupt overhead is ignored. We then present two models which describe the impact of high interrupt rate on system throughput. One model is for employing PIO in which network adapters are not equipped with DMA engines, and the other model is for employing DMA in which network adapters are equipped with DMA engines. The paper also describes detailed discrete-event simulation models for the ideal system and for systems with DMA and PIO. Simulations results as well as reported experimental measurements show that our analytical models are valid and give a good approximation. Our analysis and simulation work can be valuable in providing insight to understand and predict system behaviour, as well as improving and maintaining good host performance. The paper identifies analytically critical design operation points such as that of overload condition. The paper also proposes solutions and recommendations for improving performance. Copyright © 2005 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper we describe the main features of the Behavioral Toolbox for modeling of dynamical systems. The Toolbox, recently developed at the University of Groningen, implements the ideas on modeling which are at the heart of behavioral systems theory. In particular, it does not rely on predefined input/output descriptions and thus allows great flexibility in defining interconnections between systems. By means of an example we show how the different phases of a modeling and simulation session can be tackled within the framework provided by the Behavioral Toolbox. [ABSTRACT FROM AUTHOR]

The bucket brigades are self-balancing production lines where each human operator can move from one station to the next to continue working on a given part. When workers finish their job, they walk back to take over the ongoing work of their predecessor. For the bucket brigades, the line balancing emerges spontaneously. Several mathematical models have been proposed in literature for the analysis of bucket brigades, often where the basic assumptions seem to be too constraining. This paper analyses the behaviour of these lines when relaxing some of the usual restrictive assumptions. Two approaches are developed: analysis and simulation. An original analytical model is suggested and using this model, the sufficient condition of self-balancing for a finite backward velocity is studied. Then, a novel technique for the simulation of bucket brigades is proposed. This model uses the software Matlab/Simulink™. The results of simulation study are reported and analysed. The simulation model is flexible and easily extensible, in order to allow further embedding of complex dynamics which have not yet been considered. [ABSTRACT FROM AUTHOR]

A new concept of the dynamic connecting transport automated material handling system (AMHS) is proposed. This paper analyses the performance of the number of vehicles in a dynamic connecting transport AMHS in a simplified 300?mm wafer fab. Discrete-event simulation models are developed in e -M Plant™ to study the system performance. To avoid congestion or idle time in the intrabay system, the control of the upper limit or the lower limit on the number of vehicles can be the feasible solution. Thus, four strategies are identified and their performances are also investigated. In addition, several different operation environments such as the flow rate and the product-mix are used to investigate the performance of the dynamic connecting transport AMHS. [ABSTRACT FROM AUTHOR]

Numerical simulation of shielding effectiveness (SE) of a perforated shielding enclosure is carried out, using the finite element method (FEM). Possibilities of model definitions and differences between 2D and 3D models are discussed. An important part of any simulation is verification of the model results-here the simulation result are verified in terms of convergence of the model in dependence on the degrees of freedom (DOF) and by measurements. The experimental method is based on measurement of electric field inside the enclosure using an electric field probe with small dimensions is described in the paper. Solution of an illustrative example of SE by FEM is shown and simulation results are verified by experiments. [ABSTRACT FROM AUTHOR]

This paper presents a simulation study to assess the performance of the five known methods for converting ranks of several criteria into weights in multi-criteria decision-making. The five methods assessed for converting criteria ranks into weights are: rank- sum (RS) weights, rank reciprocal (RR) weights, rank order centroid (ROC) weights, geometric weights (GW), and variable-slope linear (VSL) weights. The methods are compared in terms of weight estimation accuracy considering different numbers of criteria and decision makers' (MS) preference structures. Alternative preference structures are represented by different probability distributions of randomly generated criteria weights, namely the uniform, normal, and exponential distributions. Results of the simulation experiments indicate that no single method is consistently superior to all others. On average, RS is best for uniform weights, VSL is best for normal weights, and ROC is best for exponential weights. However, for any multi-criteria decision-making (MCDM) problem, the best method for converting criteria ranks into weights depends on both the number of criteria and the weight distribution. [ABSTRACT FROM AUTHOR]

In this paper, a mathematical model is developed to qualitatively simulate the progressive time-evolution of a blast from a simple firework. Estimates are made for the blast radius that one can expect for a given amount of detonation energy and pyrotechnic display material. The model balances the released energy from the initial blast pulse with the subsequent kinetic energy and then computes the trajectory of the material under the influence of the drag from the surrounding air, gravity and possible buoyancy. Under certain simplifying assumptions, the model can be solved for analytically. The solution serves as a guide to identifying key parameters that control the evolving blast envelope. Three-dimensional examples are given. [ABSTRACT FROM AUTHOR]

Many facets of the behavior of shape memory alloys have enormously attracted scientists and researchers, studying and modeling their behavior are still problematic. It is in this context that several models have been developed using a lot of approaches ranging from microscopic to macroscopic scale. In this paper we have considered the superthermal effect (thermoelastic) of shape memory alloys and we have adopted a macroscopic approach. The model takes in account only macroscopic observations, it was built basing on thermodynamic laws of thermodynamics and simple assumptions in order to simplify as much as possible its use in engineering without losing accuracy. To validate the model, we have simulated numerically the response and compared it to experimental data. [ABSTRACT FROM AUTHOR]

It is well known that the fixed pitch vertical axis wind turbine (FP-VAWT) has some disadvantages such as the low start-up torque and inefficient output efficiency. In this paper, the variable pitch vertical axis wind turbine (VP-VAWT) is analyzed to improve the output characteristics of FP-VAWT by discussing the force of the six blade H type vertical axis wind turbine (VAWT) under the stationary and rotating conditions using built the H-type VAWT model. First, the force of single blade at variable pitch and fixed pitch is analyzed, respectively. Then, the resultant force of six blades at different pitch is gained. Finally, a variable pitch control method based on a six blade H type VP-VAWT is proposed, moreover, the technical analysis and simulation results validate that the variable pitch method can improve the start-up torque of VAWT, and increase the utilization efficiency of wind energy, and reduce the blade oscillation, as comparable with that of FP-VAWT. [ABSTRACT FROM AUTHOR]

In a companion paper we developed a unified scheme for using poststratified sampling and control variables to improve the efficiency of regenerative queueing simulations. We adapted these variance reduction techniques to the estimation methods of replication analysis and regenerative analysis by exploiting the asymptotic joint normality of certain standardized concomitant variables that are defined on each input process sampled during a queueing simulation. In this paper we present an experimental evaluation of the reductions in point-estimator variance and confidence-interval width that can be achieved with each procedure in several closed and mixed machine-repair systems. For the analytically tractable model, nominal and actual confidence-interval coverage probabilities are also compared. Poststratification generally produced variance reductions ranging from 10% to 40% and confidence-interval reductions between 1% and 20%. The control-variates schemes yielded variance reductions ranging from 20% to 90% and confidence-interval reductions between 10% and 70%. In some instances where small sample sizes were used, the poststratification schemes produced confidence-interval width increases between 1% and 10%. With a small number of regenerative cycles, some loss of confidence-interval coverage was observed with both poststratified and controlled regenerative analysis. When larger sample sizes were used, all of the estimation schemes yielded fairly consistent efficiency gains. [ABSTRACT FROM AUTHOR]

The paper presents original object oriented programming system ARS for modelling and simulation queuing systems. Programming system was developed in programming language C++. It establishes connection with intrinsic, but also with other Windows programming packages, in a simple way, through object oriented environment. Basic characteristics and possibilities of programming system, as well as comparative analysis of simulators: mathematical model (analytical solution)-GPSS/H-ARS, on the example of closed queuing network in the paper is given. The significant application for computer performance evaluation is reported. [ABSTRACT FROM AUTHOR]

In modern industrial practice, innovative solutions for the improvement of processes or whole production or logistical systems are continually proposed. There are many options offered, but the problem arises in verifying the correctness of decisions and their impact on the functioning of logistic processes and the entire production system after the implementation of the changes. Forecasting or experimentation can be carried out, but there are also more appropriate verification methods because changes can have a significant economic impact on the enterprise. This paper deals with the simulation and emulation of logistics processes, because the simulation is an effective tool for detecting potential in production and logistics, as well as forthe elimination of shortcomings in the design phase of a particular solution in an enterprise. Another proposed intelligent solution is emulation, as part of the decision-making and management support systems. The resulting design of the simulationemulation logistic system allows a significant shortening period of commissioning. The emulation of production systems is also intended for the rapid verification of the impact of guiding principles in advanced production systems for discrete production. These systems are called adaptive logistical systems that use the adaptability of new types of technologies based on reconfigurable production systems. [ABSTRACT FROM AUTHOR]

Copyright of Facta Universitatis, Series: Mechanical Engineering is the property of University of Nis, Faculty of Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose – The deformation of a large fuselage panel is unavoidable due to its weak-stiffness and low-rigidity. Sometimes, the assembly accuracy of the panel is out of tolerance. The purpose of this paper is to propose a method to predict and correct the assembly deformation of a large fuselage panel during digital assembly by using a finite element (FE) analysis and partial least squares regression (PLSR) method. Design/methodology/approach – A FE model is proposed to optimize the layout of load-transmitting devices to reduce panel deformation after the process of hoisting and supporting. Furthermore, another FE model is established to investigate the deformation behavior of the panel. By orthogonal simulations, the position error data of measurement points representing the precision of the panel are obtained. Then, a mathematical model of the relationship between the position errors of measurement points on the panel and the displacements of numerical control positioners is developed based on the PLSR method. Findings – The case study shows that the model has a high level of computing accuracy and that the proposed method is an efficient way to correct the panel deformation in digital assembly. Originality/value – The results of this study will enhance the understanding of the deformation behavior of a panel in aircraft digital assembly and help to improve the assembly precision systematically and efficiently. [ABSTRACT FROM AUTHOR]

Trust is an important factor for successful e-commerce and e-media applications. However, these media inherently disable many ordinary communication channels and means, and affect trust forming factors. Therefore cyber environment requires additional support when it comes to trust. This is also one key reason why computational trust management methods are being developed now for some fifteen years, while another key reason is to enable better decision making through mathematical modeling and simulations in other areas. These methods are grounded on certain premises, which are analyzed in this paper. On this basis, Qualitative assessment dynamics (QAD for short) is presented that complements the above methods. As opposed to other methods, it is aligned with certain principles of human reasoning. Therefore it further extends the scope of other computational trust management technologies that are typically concerned with artificial ways of reasoning, while QAD gives a basis also for applications in ordinary environments where humans are involved. By using this methodology, experimental work will be presented, applied to the area of organizations and human factor management. [ABSTRACT FROM AUTHOR]

In this paper, we present a case-study on application of Ramadge-Wonham supervisory control theory (abbreviated by SCT in the sequel) to a patient support system of a magnetic resonance imaging (MRI) scanner. We discuss the whole developmental cycle, starting from the mathematical models of the uncontrolled system and of the control requirements, and ending with the implementation of the obtained controller on the actual hardware. The obtained controller was tested on the physical system. In this case study, we attempted to build the models in a modular way, in order to decrease the computational complexity of the controller synthesis and to improve the adaptability of the models. An important advantage of SCT is that it allows automatic generation of the controller, and that it can thus improve adaptability of the control software. We also briefly discuss our experience on the adaptability of the control software, obtained in the course of this case study. [ABSTRACT FROM PUBLISHER]

McPherson suspension modelling poses a challenging problem due to its nonlinear asymmetric behaviour. The paper proposes a planar quarter-car analytical model that not only considers vertical motion of the sprung mass (chassis) but also: (i) rotation and translation for the unsprung mass (wheel assembly), (ii) wheel mass and its inertia moment about the longitudinal axis, and (iii) tyre damping and lateral deflection. This kinematic–dynamic model offers a solution to two important shortcomings of the conventional quarter-car model: it accounts for geometry and for tyre modelling. The paper offers a systematic development of the planar model as well as the complete set of mathematical equations. This analytical model can be suitable for fast computation in hardware-in-the-loop applications. Furthermore, a reproducible Simulink implementation is given. The model has been compared with a realistic Adams/View simulation to analyse dynamic behaviour for the jounce and rebound motion of the wheel and two relevant kinematic parameters: camber angle and track width variation. [ABSTRACT FROM PUBLISHER]

The modeling and simulation of semiautogenous (SAG) mills have been widely used in the design and optimization of mill performance in terms of its power draw, processing capacity and product size distribution. However, these models are solved under steady approximation and do not provide any information on mill charge distribution in real time. This paper attempts to characterize mill contents by solving Whiten's first-order content-based model in the MATLAB/ Simulink environment. The parameters in the model, such as breakage rate constant, discharge rate and appearance function, were estimated using process and design data collected from a gold mine operating in Alaska coupled with a nonlinear parameter estimation scheme. This model was then used to predict the dynamic responses of other key operational variables, such as mill power, bearing pressure, charge level and product size distribution. The transient response of mill behavior with respect to changes in feed size distribution, tonnage and mill feed water is also presented. This dynamic simulation approach can be used for practicing different control strategy and training purposes. The observed response of mentioned variables was validated using dynamic response data from the plant to encompass operational characteristics of SAG mill behavior. [ABSTRACT FROM AUTHOR]