bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation of a queueing problem with balking
Authors: van Tits Martien , van der Veeken Henk 
Published: March 2008

Queueing systems become complicated if balking occurs, that is, if impatient customers refuse to join the queue. Analytical results for expected queue length and waiting time have been obtained for the standard queueing problem (M/M/1) with balking. This report describes an investigation into the general validity of these formulas. Since an analytical approach to the general queueing problem is not feasible, we used simulation. An efficient simulation model was constructed and ana lysed using regenerative properties, a technique for handling correlated observations. The results extend standard queueing theory and indicate areas for further theoretical investigation.
Determining the optimum size of a coal silo
Authors: Chu Jean , Ermolowich Hichael 
Published: March 2008

We have used computer simulation to help determine the optimum size of a silo for coal produced from the McInnes Mine in Pike County, Kentucky. The silo is used to store coal that is waiting to be cleaned. Previous experience suggested a silo capacity of 6000 tons. However, because of the complexity of the operation, we undertook a further study to evaluate the proposed size. We used computer simulation to model the system and estimate the amount of lost coal production for different silo capacities. Based on the simulation results, we recommended a silo capacity of 7 500 tons to eliminate a potential bottleneck which could cause a loss of production. The total study took two weeks, including model development and preparation of the report for model uses. The cost, including man-hour charges and computer charges, was approximately three thousand dollars. We expect this study to provide savings of 1.5 million dollars, the difference in total life-cycle costs (including the cost of lost production and the initial investment) between the two proposed silo sizes. This cost/benefit ratio demonstrates the usefulness of computer simulation as a tool to solve real problems.
The simulation of gasoline queuing
Authors: Huss William R. , Cooper Ralph E. 
Published: March 2008

Lines at gasoline service stations have become a fre quent phenomenon in many countries. When lines occur, drivers demand immediate action but government and oil company officials are uncertain about what steps to take. The Battelle event-structured simulation model GASQUE is designed to show which policies are most effective in reducing the length of lines and the amount of time spent in lines. GASQUE simulates the interaction of 1 500 automobiles and three stations. Many parameters of the model are selected from distributions over time of day, day of week, or the 1 500 automobiles. Such parameters in clude purchase decision levels, consumption rates, driver availabilities, tank sizes, and station hours. The model also permits the simulation of end-user allocation plans such as assigning purchase days by automobile license number (e.g., the so-called odd- even plans). Output from the model includes statis tics such as average line length and average number of hours spent in line per week. The application of GASQUE requires the use of compara tive analysis, that is, the examination of changes from standard or base-case simulations. In one series of simulations, studying the joint effects of tank-topping (buying a small amount of gasoline sim ply to keep the tank full) and reductions in station hours shows that either may cause lines to form. Imposing a maximum purchase limitation causes longer lines, especially when combined with reduced hours. A second series of simulations studied the effects of end-user allocation plans. In general, lines are made shorter by requiring minimum purchases and re quiring stations to remain open on weekends. Odd- even plans result in longer lines. A comparison of these findings with reports from various sections of the United States suggests that the simulation results agree with the 1979 experience with gasoline queues.
Generic error control coding modules
Authors: Robinson John P. , Wade William D. , Leong Peter K. , Mortara Mary E. 
Published: March 2008

The design and test of error control encoding and decoding mod ules for simulating data communications systems is described. Generic application library modules for the Interactive Commu nications Systems Simulation Module (ICSSM) were developed for block and convolutional codes using the programming lan guage FORTRAN. The end user specifies a system for simulation study by linking various communications, signal processing and error control modules. In developing the encoding and decoding modules, a top-down approach resulted in a heirarchy of subroutines and function calls. This approach simplified the validation task and allowed easier upgrades and maintenance. Some of the design trade-offs for both the block code and convolutional code modules are viewed. It was found that modest use of storage can be traded for execution time. Various computations and operations can be efficiently accomplished with table look-up when using a high-level language such as FORTRAN. A simple communication system using these modules was studied. The error behavior was as expected. The key problems identified in this development were systems issues; primarily, module initialization and synchronization.
Visual Interactive Simulation — History, recent developments, and major issues
Authors: Bell Peter C. , O'Keefe Robert M. 
Published: March 2008

Visual Interactive Simulation (VIS) has dominated discrete-event simulation in the United Kingdom throughout the eighties. Con ceived and initially implemented by Hurrion (1976), who also coined the phrase, VIS first gained widespread exposure through the package SEE-WHY The ideas behind VIS are fundamentally different from what is referred to in the United States as anima tion, since the prime motivator is user interaction with the run ning simulation, rather than just portrayal of the simulation. After presenting a short history of VIS, we will discuss some of the research and development that has been undertaken in the United Kingdom and North America. Following presentation of an example, the state of VIS and a number of generally accepted guidelines for doing VIS are discussed. A number of recent developments, many of them also relevant to animation, and four major issues in the research and prac tice of VIS are presen ted.
Simulation as a cure process design tool for aerospace materials
Authors: Chiao Leroy , Darfler Stephen C. , Borris Peter W. 
Published: March 2008

Composite aerospace materials, known for their good mechanical properties and low weight, present interesting cure process design problems to the engineer. It is shown that computer simulation can be used as a powerful tool in solving these problems. Using physical principles, simple mathematical models are constructed which describe observed phenomena. With the advent of high-speed microcompu ters and desktop workstations, the simulations can be run at low cost. It is shown that with a properly validated model, the process engineer can use simulation to efficiently optimize cure cycles, as well as map undesirable operating regions. Examples are presented, which show that "standard" cure cycles for these materials can be modified to shorten processing times. Also, conditions which could cause reaction runaway are exposed.
Simulation analysis of some basic hypotheses about the spread of AIDS
Authors: Virkkunen Juhani , Hämäläinen Raimo P. 
Published: March 2008

The basic dynamics of the AIDS epidemic in an homogeneous population is studied from three different points of view using simple mathematical models. The first model assumes a constant transmission probability per sexual intercourse and a constant frequency of sexual intercourses. Then the probabil ity for HIV infection strongly increases with increasing number of partners only if the infection probability per intercourse is relatively high. Second, the assumption that each carrier transmits the infection a constant number of times with a constant time interval between transmissions is shown to result in an exponential rise in the number of infected. Taking the saturation effect into account the number of new infections per year and the actual proportion of infected are studied in populations of different sizes. The third model assumes an exponen tial rise in the number of infected and a randomly distributed incubation time of AIDS. This results in stochastic simula tion of the rise in AIDS cases. With repeated simulation runs the stochastic dispersion of the rise is shown to be quite large obscuring the so-called transient phenomenon in the initial phase of the epidemic.
Numerical simulation of a casting furnace
Authors: Ouellet R. , Bui R.T. , Perron J. 
Published: March 2008

Industrial furnaces constitute a complex, nonlinear, distributed- parameter thermal system. The usual way to model them is to write the equations describing the physical phenomena. The analytic model thus obtained is often too complex to be useful for control and optimization purposes. We propose to build a linear model by running the analytic model to obtain the simulated data, then apply the least square approximation to those data to obtain the linearizing coefficients. This statistical approach is simple to implement and yields linear models with good representativity. The annoying aspect is that some of the coefficients thus obtained may not lend themselves to a direct interpre tation of the physical process. But with proper consideration, this is no obstacle to the use of the model.
The design of simulation languages for systems with multiple modularities
Authors: Rowley Steve , Rocklandt Charles 
Published: March 2008

Biological systems exhibit several characteristics that are not shared by human-engineered systems: there are often no clear module boundaries (or there are several module boundaries, depending on the question being asked); individual parts often serve multiple roles, depending on the behavior being studied; and system characteristics often vary from individual to individual. Conventional simulation languages, however, do not cope well with this non-modularity. We have developed a theory of the design of simulation languages for such systems, and partially verified it in one case study. We separate the notion of "structure" S of a system from the "behavior" B of its parts. We allow multiple versions of both the structure (S1, S2, ...) and the corresponding behavior (B1,[Si], B2 [Si], ...) of each part Si. The different structures or behaviors might be alternative theories, or abstractions of each other, for example. We also have theories of how to interpret the simulations produced by (Si' B i [Si]) pairs. One goal is to extract "design" information, i.e., explain how the system solves problems. Another is to test the effects of alternative models of behavior B1 [Si], B2 [Si], ... for the same structure, or the effects on behavior due to alterations in structure. A third is to judge the relative degree of consistency between various (Si , Bi [Si]) pairs. We exhibit how these ideas apply to the motor nervous system of the nematodes C. elegans and Ascaris suum. We also provide arguments that this kind of simulation methodology is also applicable to engineered artifacts, such as systems where parts must serve multiple roles.
Conditions for computer simulation of thought processes to become actual thought
Authors: Wojcik Vladimir 
Published: March 2008

This paper is intended to break the current research impasse on issues of mechanized thought. It bypasses the untractable recursive question: Is the human brain powerful enough to understand its own working? focusing on a more tractable: Can we model, and maybe induce the process of thought? Given that this modeling effort is a particular thought process, this second question is also recur sive in nature and more general: it permits us not to consider the limitations of our brains due to their biological implementa tion. In this article I model the concepts of complexity, error, surprise, intuition, thought and insight. I also analyze the concepts of consciousness and feelings. I describe the features any thinking system must have. It appears that humans might be able to create such systems in future.
Simulating a JIT/kanban production system using GEMS
Authors: Swinehart Kerry D. , Blackstone John H. 
Published: March 2008

Just-in-time refers to the movement of material at the necessary place at the necessary time. The implication is that each operation is closely synchronized with the subsequent ones to make that possible. A method of just-in-time production which uses standard containers with a single card attached to each. It is a pull system in which work centers signal with a card that they wish to withdraw parts from feeding operations or vendors. Kanban, in Japanese, loosely translated means, "card ", literally "billboard" or "sign ". The term is often used synonymously for the specific scheduling developed and used by Toyota Corporation in Japan.
COSMOS: A simulation language for continuous, discrete and combined models
Authors: Kettenis Dirk L. 
Published: March 2008

COSMOS is a new simulation language for description of continuous, discrete or combined continuous/discrete models. For continuous models, the COSMOS language definition constitutes a superset of CSSL with many additional structuring elements being incorporated, e.g. for convenient modelling of piecewise continuous models and variable structure systems. Discrete models are coded according to the process interaction world view. The design of the language constructs makes it possible to write simulation programs in accordance with modem software engineering methodology. The model and experiment description, for example, are totally separated. In addition, models can be separated into submodels.
Simulation of the experiment data from WINDII flown on the UARS/NASA satellite
Authors: Thuillier G. , Christophe J. , Azria G. , Herse M. , Fauliot V. , Girod F. , Fratter C. , Thouvenin J.P. , Solheim B.H. 
Published: March 2008

The WINDII instrument (Wind Imaging Interferometer) is dedicated to the measurement of the temperature and wind in the upper Earth's atmosphere. It was launched with the NASA-UpperAtmosphere Research Satellite on September 12, 1991. It analyzes the natural emission lines of the atmosphere by an inteiferometric method to extract the temperature and wind information. Such a mission requires building the instrument, preparing its modes of operation, its scientific data processing, and evaluating its performance. To achieve these last tasks simulated data are needed. Which is why we have developed a quite extensive code of simulation which consists of several models: instrument, atmosphere to be observed (temperature, wind and intensity), orbit and attitude, and instrumental noises. The simulated data have permitted the evaluation of certain instrument effects and suggested some improvements of design. The effects of the various sources of noise have been studied. Scenarios of observations have been derived allowing the study of the scientific data processing algorithms and evaluation of their performances. Simulation of such a space instrument has been seen as an essential step in the design of the mission.
MADCAPP: Measurement and analysis of high-level communications of asynchronous distributed algorithms on parallel processors
Authors: Gillis Colin W. 
Published: March 2008

The issue of correctness of complex asyn chronorcs distributed algorithms imple mented on loosely coupled parallel processor systemsis difficult to address given the lack of effective debugging tools. In such systems, messages propagate asynchronously over physical connections and precise knowledge of the state of every message in the system at any instant of time is difficult to obtain. For a particular class of asynchronous distrib uted algorithrns [1,2,5] that may be charac terized by independent models that execute asynchronously on the processors and interact with one another only through explicit messages, the following reasoning applies. Information on the flow and content of messages and the activity of the processors is significant towards under standing the functional correctness of the implementation. This paper proposes a new approach , MADCAPP, to measure and analyze high- level message communication and the activity level of the processors.
Coverage and Performance Predictions for the North-West European Loran-C System
Authors: Last David , Searle Mark , Farnworth Richard 
Published: March 2008

In 1991 six European nations, Denmark, France, Germany, Ireland, The Netherlands and Norway, agreed to co-operate in deploying a Loran-C system to cover North-West Europe and the North Atlantic Ocean. The system will comprise 9 stations arranged in 4 chains. In estimating the coverage which will be provided, the effects of signal attenuation, atmospheric noise, carrier- wave interference, skywave propagation, the change of envelope-to-cycle difference with range and transmitter timing uncertainty ,have all been taken into account. Contours of repeatable accuracy have been predicted for both conventional hyperbolic receivers, which employ the signals of a master and two secondary stations of a single Loran-C chain, and receivers which work in the semi-circular, cross-chain and master-independent modes. A standard receiver with specified bandpass, notch filter and tracking loop characteristics has been adopted as the basis for coverage and performance assessment. Further, in a rigorous search was carried out forgroup repetition interval (GRI) values which minimised the numbers of synchronous and near-synchronous interferers in the area covered by each chain. The very substantial variations of coverage with choice of GRI were explored and optimal GRI values selected.
Throughput Analysis of Multiple-Bus Multiprocessor Systems with Simultaneous Possession of Common Resources
Authors: Önyüksel Ibrahim 
Published: March 2008

To answer the questions for the performance issues of multiple-bus multiprocessor systems under general conditions, a discrete-event simulation model has been developed. This model has been analyzed for different types of probability distributions for random variables A = processing times and B = memory access times for processors. For variables A and B, the following types of distributions are employed: exponential, Erlang, hypoexponential, hyperexponential, normal and constant. Simulation experiments show that the coefficient of variation of B, CB has a significant effect on the system performance, especially for CB>1, but the effect of CA is negligible if A is either hypo- or hyperexponentially distributed. However, this is not the case for a normal distribution. Processing efficiency, memory utilization and the percent of queued processors are some of the performance metrics used in our simulation model. We simulated several multiprocessor configurations and reach the conclusion that if the number of buses is equal to half the minimum value of the number of processors and the number of memory modules, the corresponding bus-deficient system behaves as a bus-sufficient system. Clearly, this is a substantial saving for the required number of buses without degrading the system performance.
A Distributed Approach to Real-Time Payments-Processing in a Partially-Connected Network of Banks: Modeling and Simulation
Authors: Lee Tony , Ghosh Sumit 
Published: March 2008

The payment-processing system in the banking industry consists of deposits, withdrawals, and transfers of monies through the use of cash, checks, magnetic tapes, and electronic transactions. Of these, nearly all of the check processing through the United States Federal Reserve System, most of the check processing in the private networks, and a part of the electronic transactions are realized through the utilization of the principles of batch- mode processing. Batch-mode processing suffers from many limitations, the principal ones being that (i) users are denied real-time access to their money and that (ii) a user's banking privileges cannot be extended anywhere in the USA — a facility that is increasingly being demanded by users. This paper observes that the banking process may be mathematically mapped to a discrete-event simulation system with feedback loops wherein deposits, withdrawals, and transfers may be modeled as events that are introduced into the system asynchronously i.e., at irregular intervals of time. It proposes a new, distributed architecture for payments processing within a network of major banks as an alternative to the Federal Reserve System. This approach distributes the processing operations to multiple, concurrent, cooperating geographically distributed computers i.e., at many sites, to achieve real-time transaction processing. It utilizes the principles of asynchronous, distributed, discrete-event simulation algorithm utilizing pseudo- transaction (timestamps), and mathematically guarantees the accrcracy of every transaction. Given that the major banks are geographically distributed throughout the entire country, the distributed nature of the algorithm, proposed in this paper, is extremely appropriate. It offers the hope of a banking system that is available, transparently, to a user anywhere within the coverage area of the network. While the balances of accorents at each of the major banks are owned exclusively by the respective banks, thereby implying privacy and security, any transaction inserted anywhere in the system is guaranteed to be correctly routed to the target bank for execution. This architecture assumes that the banking nodes are partially connected through a broadband-ISDN Network. The choice of B-ISDN is timely given the importance of global, electronic banking in the world economy and CCITT's desire to standardize B-ISDN for all telecommunications in the world. This paper also reports on an implementation of a model of a network of major banking nodes on a network of SUN workstations, configrcred as a loosely-coupled parallel processor system, at Brown University. Performance analysis indicates that this approach achieves a very high throughput for transaction processing.
Building Intelligence Into an Autopilot -- Using Qualitative Simulation to Support Global Decision Making
Authors: de Albornoz Alvaro , Cellier François E. 
Published: March 2008

This paper represents an addendum to an earlier paper published by the same research group in SIMULATION in 1989. In the earlier paper, a crisp inductive reasoner had been employed to qualitatively reason about the behavior of a quantitatively simulated B- 747 aircraft, to determine when a structural malfunction occurs, to hypothesize about the nature of this malfunction, and to decide upon a global strategy that allows operation of the quantitative aircraft model under the modified flying conditions. In the addendum, the formerly crisp inductive reasoner has been replaced by a fuzzy inductive reasoner. The paper demonstrates the enhanced discriminatory power and the improved forecasting capability of the modified reasoning scheme. In addition, the fuzzy inductive reasoner allows prediction of a quasi-continuous response spectum, whereas the crisp inductive reasoner was able to predict discrete (class) values only.
I ONLY MEANT TO TEST THE WATER, but I fell in over my head. (Now I must try to dog-paddle to firm ground.)
Authors: McLeod John , McLeod Suzette 
Published: March 2008

In Simulation in the Service of Society in the May issue of SIMULATION I asked "Is Simulation a Possible Tool for Peace?" I traced appli cable simulation technology from WW II to the present, and concluded that Peace Gaming was worth a try. Before publishing the article, I sent the Introduction and Conclu sion to the Directors of the various MISS (McLeod Insti tute for Simulation Science) Centers plus some friends and colleagues, asking for comments. The following are excerpts from some replies, necessarily anonymous because I have not yet gotten permission to quote.—JM