bluuebunny/crossref_metadata_2025 huggingface dataset:
Oculomotor adaptation with virtual reality scotomas
Authors: Bertera James H.
Published: March 2008

A simulation of central blindness in normal human subjects was produced by linking a high- accuracy eye position sensor with a computer visual display. This eye controlled system may be classified as a form of virtual reality for safely exploring the effects of visual defects, diseases, and adaptability under experimental control. A circularly symmetric simulated scotoma or visual blindspot was stabilized on the fovea of 6 normal observers while they attempted to maintain a target in clear view. The subjects were naive and were free to view the target in any way they chose. Eccentric eye positioning developed within 2 minutes of viewing time with most subjects. Cumulated fixation positions showed that the edge of the scotoma was positioned next to the target. All subjects reported that they found an upper right position relative to the target easier to maintain as an eccentric vantage point and fixation maps showed that the majority of fixations were located there. The durations of correctly positioned fixations became longer during eccentric viewing practice indicating rapid improvements in fixation stability, while fixation durations of incorrect, error fixation positions became shorter demonstrating adaptability. A test for eye fixation stability around clock positions failed to explain the upper right field preference as an eccentric viewing point.
Simulating biological vision with hybrid neural networks
Authors: Sajda Paul , Finkel Leif H.
Published: March 2008

We present an example of how vision systems can be modeled and designed by integrating a top-down computationally- based approach with a bottom-up biologi cally-motivated architecture. The specific visual processing task we address is occlusion-based object segmentation — the discrimination of objects using cues derived from object interposition. We construct a model of object segmentation using hybrid neural networks—distributed parallel systems consisting of neural units modeled at different levels af abstraction. We show that such networks are particularly useful for systems which can be modeled using the combined top-down/bottom-up approach. Our hybrid model is capable of discriminat ing objects and stratifying them in relative depth. In addition, our system can account for several classes of human perceptual phenomena, such as illusory contours. We conclude that hybrid systems serve as a powerful paradigm for understanding the information processing strategies of biological vision and for constructing artificial vision-based applications.
HARVEST: A generalized animal population growth simulation
Authors: Stewart David J. , Amlaner Charles J. , Barnett Claude C.
Published: March 2008

We present a general purpose discrete-event, stochastic simulation model (HARVEST) which can be used to model the population growth of a wide variety of animal species. A complete example is given with valida tion, to show how it can be used for managing the Eastern wild turkey. The structure of the simulation system (micro Passim) is described, and the implementa tion of the model is discussed as an example of how the process-interaction simulation protocol may be used to represent a complex natural system. The model is designed to be used by state and federal wildlife agencies for exploration of the effects of potential hunting regulations on actual populations of game species.
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.
A "neural" network model that supports realtime learning of temporal relationships in complex engineering domains
Authors: Morrison John D.
Published: March 2008

Difficulties in developing, maintaining, and validating knowledge base have motivated an increasing interest in adaptive systems. However, the symbolic paradigm has proven resistant to learning in environ ments that are dynamic or noisy. This report documents a simulation-based research program that demonstrates the utility of a modified connectionist memory unit as the basis for a robust reinforcement model that learns in such environments. This learning model generates effective rule- based behavior from a qualitative, goal-based architecture that further supports the development of secondary goals, or mental models, derived from experiences in these complex domains.
PCRSM: A decision support system for simulation metamodel construction
Authors: Meidt Gregory J. , Bauer Kenneth W.
Published: March 2008

A general procedural area which applies regression theory, experintental design, and optimization theory is Response Surface Methodology (RSM). Metamodelling using RSM techniques is a popular method for analyzing simulation models. This paper presents a microcomputer based decision support system called PCRSM which acts as an aid to employing RSM in simulation studies. An example of PCRSM's use is presented using a simulation model of a personnel system.
Guidelines for the design of data driven generic simulators for specific domains
Authors: Pidd Michael
Published: March 2008

Data-driven generic simulators have, for many years, been used to model a wide range of systems. Some such simulators are promoted as general purpose, while others are specific to particular problem domains. This paper considers how domain-specific data-driven simulators should be constructed using a modular approach which allows the simulator to be incrementally enhanced and ported easily to alternative computing environments. It also argues that generic simulators will not wholly replace simulation programming for specific applications.
A Framework for Distributed VLSI Simulation on a Network of Workstations
Authors: Karthik Sankaran , Abraham Jacob A.
Published: March 2008

A distributed framework for logic simulation is presented. Switch-level simulation has been mapped to a distributed platform using a network of workstations on an Ethernet bus. Model parallelism is used with preprocessing to partition the circuit to be simulated among the processors. The simulation algorithm is decoupled from the communication layers to ensure easy portability. We have proposed a high level pipelining scheme with multiple buffers to overcome the effects of a low bandwidth network. Speedups of up to 4.1 with 5 processors have been obtained for medium sized ISCAS benchmark circuits. The speedups achieved using distributed simulation are very close to that obtained by the same switch-level simulator imple mented on a shared memory parallel machine. Novel techniques to improve the performance of distributed simulation have also been implemented on a shared memory parallel machine.
A User-Centered Paradigm for Interactive Simulation
Authors: Rooks Michael
Published: March 2008

Computer software for modelling dynamic systems has existed for over three decades. During this period, computer modelling and simulation have been enhanced by powerful simulation languages, graphical modelling techniques, and statistical techniques. A recent trend in simulation software develop ment has been the addition of many analysis tools to existing simulation languages. An examination of these tools indicates that they are predominantly independent of the application area for which the simulation language is designed, suggesting that a general library of simulation analysis tools should be created for use with several simulation languages. A user-centered approach to simulation software design provides an application- independent description of the model analyst's needs. This description is the basis for a general environment within which simulation languages and models may be implemented, and prevents the redundant coding of application-oriented simulation software. It improves on the traditional language-centered approach, which first describes a simulation system in terms of an application language, and considers the experimental interface as secondary. This paper motivates and describes the design of user-centered software for visual interactive simulation.
A New Model of Incremental Decision Making for Resource Acquisition by Electric Utilities
Authors: Hirst Eric , Yourstone Evelin , Gettings Michael
Published: March 2008

Electric utilities have developed and applied several new ways to address the uncertain ties they face in resource planning. In these methods, however, all the resource-acquisi tion decisions (e.g., construction of power plants and operation of energy-efficient programs) are made at the beginning of the simulation. This paper describes a new model that explicitly deals with the fregnent, incremental nature of utility decision making. This model requires users to interact with model results and forecasts after every year or two of simulation. At that time, the user can initiate new resource acquisitions or modify past decisions (e.g., slow down construction of a power plant or change the marketing budget for an energy- efficiency program).
Simulation of Combinational Circuits for Fault Diagnosis
Authors: Vishnubhotla Sarma R.
Published: March 2008

Simulation techniques are discussed to build test patterns to diagnose hardware faults in digital circuits. Only combinational circuits without redundant wires or undetectable faults are considered. All faults are assumed to be either stuck-at type faults or bridge-faults. An algorithm is presented to build test patterns, based on the circuit structure. The set of tests obtained from this algorithm is shown to have the diagnostic resolution to diagnose all the stuck-at type multiple faults and bridge-faults in the circuit. The simulation program accepts the circuit description as an input. It will store the details of the circuit in data structures that will enable the program to traverse both to the primary inputs and to the primary outputs from any wire. It is illustrated how the simulation program builds the test patterns, finds the fault ranges of each test and finally builds the fault dictionary of the circuit. A theory is presented to prove the completeness of the diagnostic resolution of the obtained test-set.
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.
Determination of the Toss Speed for an Automotive Valve-Gear System
Authors: Méndez-Adriani José A.
Published: March 2008

This research presents an improved lumped- parameter model that combines favorably its simplicity and precision to represent appropriately an automotive valve-gear system, by means of the inclusion of a fluidic pressure element within the modeling of the hydraulic lifter, and by considering the hysteretic behavior of the pushrod under cyclic loading. Realistic values have been chosen for the parameters of this cam-follower mechanical system, and the checking of this modified mathematical model has been accomplished by means of a qualitative comparison with other models previously conceived, and with previous experimental results obtained from an automobile engine. The digital computer simulation allows the determination of the cam speed for which the valve toss occurs, whose value is of fundamental importance in evaluating the design of automotive cam mechanisms.
A Generic Simulation Module Architecture Based on Clustering Group Technology Model Codings
Authors: Ozdemirel Nur E. , Mackulak Gerald T.
Published: March 2008

Simulation experts know very well that there are similarities between the models they build for different manufacturing system. This article describes a module based generic model generator for discrete manufacturing systems. The module based generator was developed from a group technology (GT) classification scheme. The GT scheme uses common model features as a basis for creating generic model components. Specific user models are constructed by modifying and configuring the generic models rather than building them from scratch, thus reducing the effort and skill expected of the user in the process of model abstraction, construction, and validation/ verification.
Operator-in-the-loop simulation of a redundant manipulator under teleoperation
Authors: Yae K.H. , Lin T.C. , Chern S.T. , Frisch H.P.
Published: March 2008

For an interactive simulation of 7 degree-of freedom redundant manipulator under teleoperation, this paper describes an iterative form of resolved-motion rate control in which the constraint Jacobian is constructed on-line in real time and used in the pseudoinverse method as the manipulator is teleoperated. The manipulator's tasks may involve trajectory following in free space and frequent contact with the environment through pick-and-put operation. The operator's command is interpreted as a series of increments in Cartesian space, and then the constraint Jacobian is developed between two successive increments by viewing the predecessor as the initial configuration and the successor as the target configuration. The pseudoinverse of the constraint Jacobian then generates necessary changes in joint variables and subsequently joint torque. The Jacobian constructed in this way enables us to treat both free motion and environmental contact in the same way. The simulator is built on a two-processor IRIS workstation, with one processor for graphics and the other for dynamics and control analysis. This simulator has a potential for training the teleoperator, developing operational scenarios through visualization of the simulation, and testing the design of operator-machine interface.
The role of terrain modeling in lunar rover simulation
Authors: Rao Niranjan S. , Appleby Matthew H.
Published: March 2008

This paper presents work being performed by Boeing on the next generation of lunar rovers as part of the Space Exploration Initiative (SEI). The current work has emphasized development of a lunar rover simulator. Such a simulator will be used for design and analysis of rover mobility system concepts and derivation of requirements for vehicle design and performance. The quality of rover design depends on the fidelity of the models that comprise the simulation tools. One of these models is a lunar terrain model that was developed in the course of work on the rover simulator. This model is the first step in the development of the rover mobility system simulation, for the design of the mobility system, which includes the drive, steering, and suspension systems. Mathematically modeling the interaction between the terrain and vehicle requires sound models of the terrain and the vehicle. This paper discusses the role of the lunar terrain model in rover simulation as part of the rover vehicle design process.
A Comparison Study of Two Tests for Detecting Initialization Bias in Simulation Output
Authors: Xiping Ma  , Kochhar Ashok K.
Published: March 2008

This paper presents a comparison study of two statistical tests for detecting initializa tion bias in discrete-event simulation output. These two tests are the so-called optimal test and rank test developed and presented by Schruben et al. [1] in 1983 and Vassilacopoulos [2] in 1989 respectively. In the comparison experiments, artificially generated stochastic sequences are used as input to the tests. Such a sequence is obtained by embedding specified initializa tion bias into an unbiased stationary stochastic sequence. The results of the experiments have shown that both tests do perform satisfactorily in a similar way. It is noted that the optimal test is more sensitive to initialization bias, and therefore has consistently outperformed the rank tests when significant initialization bias is present in the tested sequences. However, since the rank test is simpler to implement and easier to use than its counterpart, it is expected that it will also find wider accep tance and application in the future.
Development of a goal directed simulation environment for discrete part manufacturing systems
Authors: Prakash Subramanian , Shannon Robert E.
Published: March 2008

The development of a goal directed simulation environrnent for discrete part manufacturing systems is discussed. A two phase approach was taken for the development of the nile base. The first phase involved studying different types of manufacturing systems in order to identify the cause-and-effect relationships that an analyst may use during analysis. Based on the "expert" knowledge identified in this phase, and subsequent experimentation, a detailed set of rules was developed. The rule base has a four level structure. Of these, Levels 2, 1, and 0 are generic, while the fourth level is comprised of information specific to the system under consideration.
Functionality and Implementation of a Knowledge-Based Flowsheet-Oriented User Interface for the Dynamic Process Simulator DIVA
Authors: Bär M. , Schaffner J. , Selg W. , Zeitz M.
Published: March 2008

A knowledge-based simulation model editor for the dynamic process simulator DIVA allows flowsheet generation guided by object-oriented, hierarchically structured knowledge about process-units, and by rules ensuring the consistency of parameters and connections between process-units. A physical property interface helps the user to choose from various calculation methods offered by the simulator's library. Parameters for the substances at hand are retrieved from inhouse and commercially available physical property databases. The tight integration of facilities for experiment control and flowsheet animation will be the basis for future studies in knowledge-based process optimization and process control.
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.
Supporting a Simulation Environment with OpenSim
Authors: Mutka Matt W. , McKinley Philip K.
Published: March 2008

This paper presents the design, implemen tation, and usage of OpenSim. OpenSim provides new tools and integrates existing tools into an environment in order to establish a comprehensive facility for performing simulation work. First, OpenSim provides a graphical user interface for creating input files for simulations and for managing output files produced from simulations. Second, tools are provided to help a user easily generate plots from sets of output files associated with a simulation project. Third, OpenSim addresses a common problem for many simulation users, namely, lack of computing capacity to serve the jobs. In order to solve this problem, OpenSim integrates Condor, an existing system that clusters idle workstations into a processor bank, into its environment. Through Condor, users have access to a large amount of computing capacity without interfering with the local usage of workstations by their owners. Finally, since users often plan their schedules according to the deadlines required for their jobs, OpenSim enhances Condor so that users can request jobs to be scheduled within a deadline. Therefore, a user can expect that the amount of computing capacity required for a simulation project will be available before a specified deadline.
Forecasting Retail Sales and Dealer Inventories: A Simulation and Decision Support System
Authors: Spiegler Israel , Herniter Jerome
Published: March 2008

A simulation model for forecasting retail sales and dealer inventories is presented. The model is based on the average time in distribution (ATD), a new statistic calculated from warranty cards returned by customers after purchasing a product. While warranty card returns are highly random both in number and arrival rate, the ATD is a relatively stable indicator rarely used in forecasting. Sales and inventories are generated by fitting their estimated ATDs to warranty cards. A decision support system (DSS), incorporating the simulation model as well as the standard components database, model base, user interface, report and graph facilities is outlined and discussed.
Objects for Simulation: Smalltalk and Ecology*
Authors: Baveco J.M. , Smeulders A.M.W.
Published: March 2008

The object-oriented programming environment Smalltalk is used to implement a tool for modeling and simulation of ecological systems. This PC-based tool makes it possible, and easy, to represent individuals explicitly in the simulation, and to integrate the individual-based approach with a traditional population/concentration-based approach. Object-oriented programming is used to allow for an efficient development of models. The properties of Smalltalk are exploited to make testing and investigation of the models occur interactively, supported by a user-friendly interface. In the paper, modeling and simulation concepts and elements of object- oriented programming as they relate to an individual-based approach, are introduced. The simulation extension in question (EcoTalk) is described. Two applications that make use of EcoTalk are presented, both related to population-dynamics. The discussion centers on practical implications of the approach, e.g. the system characteristics that can be expressed in EcoTalk. An indication of the performance of an application is given. It is concluded that, at present, EcoTalk can be used for medium-sized applications.
Visual Translucent Algorithm (Vista)
Authors: Boehm Albert R.
Published: March 2008

VISTA (VISual Translucent Algorithm) is a fast, 4-D cloudscape generator that includes simulation of haze and cloud- related visual phenomena such as cloud shadows, rainbows, and solar arcs. VISTA uses a meteorological sounding as input and produces cloud scenes using a backward ray tracing technique. The ray is checked for the first intersection of either 1) an opaque surface (thick cloud or surface), 2) a translucent layer, or 3) an optical refraction layer. Depending on the nature of this intersection, the specular reflection is calculated after taking into account direct illumination, if any. Placement of clouds depends on location of potential cloud layers, cloud domain characteristics, and gravity waves, while small (of order 1 meter) cloud structure is stochastically generated by a sawtooth generator. Background land surfaces can be deterministically (either real or hypothetical) input or can be stochastically generated.
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.
Real-time Environment and Vehicle Dynamics Simulations for Space Station Freedom Integrated Test and Verification Environment
Authors: Guyse Carolyn Jayne , Buscher Deborah Elaine , Ellenberger S. Richard
Published: March 2008

To reduce the costs associated with developing real-time simulations needed for the Space Station Freedom (SSF) Integration, Test and Verification Environment (ITVE), the National Aeronautics and Space Administration (NASA) investigated the possibility of integrating existing simulations with the ITVE. The purpose of this paper is to present a five-step generic approach for "retro-fitting" existing, NASA-owned simulations into the ITVE, as opposed to developing ITVE-specific simulations. The goals of the approach were (1) to minimize the modifications required to successfully integrate an existing simulation with the ITVE, and (2) to minimize the amount of knowledge and insight needed into the simulation to make the modifications. The five-step approach is generic in that it may be applied to any simulation that is being considered for integration with the ITVE. To test the approach, a NASA-MITRE team applied it to a subset of the Multiple Orbital Object Dynamics Simulation (MOODS) system. The results of that exercise are presented in this paper.
Constrained Multibody Dynamics Library Within EASY5
Authors: Yae K.H. , Lin T.C. , Lin S.T.
Published: March 2008

Nonlinear multibody dynamics of a constrained mechanical system has been merged into the Boeing EASY5 Engineering Analysis System. This merger completnents EASY5 control modeling and analysis with nonlinear multibody dynamics. The merged tool creates an environtnent for controls and nonlinear dynamics simulation within a single package. It is capable of time simulation with a high-fidelity nonlinear dynamic model, and is also capable of frequency- domain analysis after the model has been linearized at a selected configuration within the EASY5 environment. It can significantly cut down the time reguired in converting models between dynamics and control packages. This merged package has been successfully implemented and applied to various applications.
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.
Order Release in JIT Production Systems: A Simulation Study
Authors: Takahashi Katsuhiko , Nakamura Nobuto , Ohashi Kenichi
Published: March 2008

As an order release system for multi-stage production inventory systems, this paper deals with the Kanban system of Just-in- Time (JIT) production. This paper develops a queuing network model of the Kanban system with a simulation language for discrete-event simulation, SLAM II. Also, this paper aims to improve the Kanban system by modifying the flow of information. By means of discrete event simulation, the performances of the models are investigated and compared.
A Remote Laboratory Using Virtual Reality on the Web
Authors: Schmid Christian
Published: March 2008

This contribution presents a remote laboratory approach using virtual reality on the Web. Extensions like plug-ins and Java applets, which use MATLAB/SIMULINK for simulations, are integrated into the Web browser. Interactive animation of control engineering experiments can be performed using VRML models of labo ratory plants. The Web-based techniques for realising a virtual laboratory of this kind are introduced and discussed in detail. The main characteristics of this Web-based simulation approach are demonstrated with help of an ex ample from a learning system including virtual laboratory camponents. The central focus of this contribution is on the technical realisation of the most important elements. Some virtual laboratory examples illustrate the usefulness of this approach.
Near Real-Time Agricultural Simulations on the Web
Authors: Georgiev Goshko A. , Hoogenboom Gerrit
Published: March 2008

Easy access to the Internet allows farmers to search for site-specific information and applications. The agricultural scientific community has developed computer simulation models and decision support systems during the last 20 years in order to transfer scientific knowledge to farmers. We describe an at tempt to create an Interrzet-based decision support system for delivering weather data and executing near real-time weather applications and crop simu lation models on the Web. A user accesses an easy- to-use interface to select management scenarios and run crop simulation models remotely. The weather data inputs are linked to data collected by the Geor gia Automated Environmental Monitoring Net work. A user defines a scenario by selecting a crop, cultivar, planting date, plant density and spacing, irrigation schedules and fertilizer inputs. After de fining all inputs associated with the scenario, the simulation model runs remotely on the server. The proposed distributed processes scheme can be imple mented on different platforms. Client/Server, CGI, Perl and other Internet technologies are providing a cost-effective, robust and simplified access to crop simulation models for the user community.
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
Simulation of the IARC NASDA Information System Archive and Analysis Subsystem Using Extend™
Authors: Bazell David , Geller Harold
Published: March 2008

In this paper we present a discrete event simulation of the Archive and Analysis Subsystem (AAS) to be installed by the Japanese space agency, NASDA, as part of the Japanese contribution to the Interna tional Arctic Research Center (IARC) at the Uni versity of Alaska, Fairbanks (UAF). Scientists will utilize the AAS to support their Arctic research. The objective of this effort is to develop a simula tion model that will allow engineers to anticipate the loading of certain system components, especially the storage and network subsystems. At the start of this effort we determined that the simulation mod eling software Extend™, a product of Imagine That, Inc., of San Francisco, would be most appropriate in meeting our objectives within the given cost and time constraints. We present our architecture and model assumptions within the context of the engi neering design of the AAS. We also present results in the form of graphical displays from the model output, based upon our assumptions. We describe some of the difficulties encountered in making use of the Extend™ simulation software in modeling our subsystem and our approach to overcoming these difficulties.
Computer Simulation of the Effect of Thermal Contact Resistance on Cooling Time in Injection Molding
Authors: Sridhar L. , Narh K.A.
Published: March 2008

Thermal contact resistances (TCR) play an im portant role in heat transfer. TCR is therefore of significance in the simulation of injection mold ing processes where one of the factors determin ing productivity is the cooling time. Simulation software packages either consider TCR as negli gible or use a constant value based on steady- state conduction, whereas in injection molding, TCR is time-dependent. We use simulation of the injection molding process to show that using TCR values within the range obtained from steady state experiments may lead to underpre dicting cooling times by up to 15% and, hence, there is a need to use time-dependent TCR in the heat transfer simulations. Our simulation result indicates that the value of TCR also affects the frozen layer fraction in the early postfilling period.
Simulation in the Service of Society
Authors: McLeod John , McLeod Suzette , McLeod John
Published: March 2008

In our August issue we presented ex cerpts and comments to tell you about a book Modeling the Environment by Andrew Ford, Associate Professor of Environmental Science and Regional Planning at Washington State Univer sity, Pullman, Washington. If you missed that writeup, you can find out all about the book at http:// www.islandpress.org/ford. Or better yet, you can read the very interesting book.

What follows is Appendix K from the book, which ap pealed to me particularly because of its perceived potential ity for teaching by appealing to students' penchant for game playing. Individual students, or groups, can compete to achieve goals suggested by the author—and learn a lot about river systems and their control.

It would seem that the Idagon model would also lend itself to modification for the study of real river systems. It is de scribed in the following edited excerpt from the book.—JM
Discrete-Event Models of Mixed-Phenotype Plasmodium falciparum Malaria
Authors: McKenzie F. Ellis , Wong Roger C. , Bossert William H.
Published: March 2008

We extend our basic discrete-event model of Plasmodium falciparum malaria to encom pass circumstances in which multiple pheno typic variants of the parasite circulate within interacting human and mosquito populations, and we compare a version in which variants behave independently to one in which they in teract through shared host immune responses. Relative to the standard hypothesis of statisti cal independence, frequencies of mixed-pheno type infection in humans were as expected in the independent-immunity version and much less than expected in the cross-immunity ver sion ; in both versions, however, such frequen cies in mosquitoes were much greater than expected.
Exploiting HLA and DEVS To Promote Interoperability and Reuse in Lockheed's Corporate Environment
Authors: Zeigler Bernard P. , Hall Steve B. , Sarjoughian Hessam S.
Published: March 2008

Joint MEASURE™ (Mission Effectiveness Analysis Simulator for Utility, Research and Evaluation) demonstrates the effective applica tion of HLA-compliant simulation outside the traditional realm of training to analytic studies of mission effectiveness of systems within larger systems of systems configurations. This paper discusses how Joint MEASURE effectively ex ploits both the DEVS modeling and HLA simu lation frameworks to support high performance distributed simulation and thereby, to overcome impediments to interoperability and reuse of Lockheed's models arising from the reluctance of groups to share their code at the source level with others within the corporation.
Migration of HLA into Civil Domains: Solutions and Prototypes for Transportation Applications
Authors: Schulze Thomas , Strassburger Steffen , Klein Ulrich
Published: March 2008

The United States Department of Defense's (DoD) High Level Architecture for Modeling and Simulation (HLA) is a mandatory stan dard for military simulations. The situation in the civil simulation community is differ ent : simulator interoperability is desirable and even required, but there is no driving force to mandate the use of a certain standard. This article addresses the problems that a simulator interoperability standard in the civil world faces and discusses how HLA can possibly become the standard that is needed. Several solutions for connecting civil simula tion tools using HLA are introduced and some prototypical applications focusing on the area of transportation are demonstrated.
Discrete-Event Simulation Software: What the Users Want
Authors: Hlupic Vlatka
Published: March 2008

Due to the increasing popularity of simula tion, there are numerous simulation software tools available on the market. This paper pre sents the results of a survey on users' re quirements of discrete-event simulation software. The survey involved members of the Simulation Study Group of the Operational Research Society of Great Britain. Findings of the survey indicate which types of simula tion software are primarily being used, the most common application areas of simulation, and users' opinions about software and pos sible ways of improving simulation software.
Interplay of Negative Emotion and Health Self-Efficacy on the Use of Health Information and Its Outcomes
Authors: Sun Young Lee  , Hwang Hyunseo , Hawkins Robert , Pingree Suzanne
Published: March 2008

During the course of illness, people diagnosed with cancer need information to cope with cancer. Despite the crucial role of information, little is known about why some people with cancer choose to seek further information about their illness and why others do not. This study investigates the interplay of two psychological factors, negative emotion and health self-efficacy, on patients' health information use. Using the data collected from 122 women diagnosed with breast cancer, the authors found that negative emotions and health self-efficacy jointly affect the use of health information. Among patients with high health self-efficacy, negative emotions were positively related to the amount of information sought, whereas among those with low health self-efficacy, negative emotions were negatively related to the amount of information sought. The results also show that there are significant increases in patients' health self-efficacy after the use of health information for 2 months.
Restless Legs Syndrome in Type 2 Diabetes Implications to Diabetes Educators
Authors: Cuellar Norma G. , Ratcliffe Sarah J.
Published: March 2008

Purpose The purpose of this study was to provide a background of restless legs syndrome (RLS), present the prevalence and demographic findings of a descriptive study of type 2 diabetes with RLS, and provide implications to diabetes educators on the management and education of RLS.

Methods Participants with type 2 diabetes who met the diagnostic criteria for RLS based on the International RLS Study Group Criteria were recruited from the PENN Rodebaugh Diabetes Center from July 2005 through September 2006. Participants who met inclusion and exclusion criteria were mailed a survey to collect data.

Results Of 121 patients with type 2 diabetes, 54 (45%) of the screened sample met the 4 diagnostic criteria for RLS. Of those who met the inclusion and exclusion criteria of the primary study, 18 patients with type 2 diabetes with RLS participated in this study. Along with diabetes, the par- ticipants had a variety of comorbid health conditions including hypertension, neuropathies, rheumatoid arthritis, renal failure, and irritable bowel syndrome. Only one third of the participants were being treated for RLS. Thirty-nine percent of the participants with type 2 diabetes were using insulin to manage their diabetes with other oral agents.

Conclusions RLS is a sleep disorder that may affect the management of type 2 diabetes. Diabetes educators must know that sleep disorders can affect long-term health outcomes, and RLS is frequently seen in this cohort of patients.
A Qualitative Assessment of Barriers and Facilitators to Achieving Behavior Goals Among Obese Inner-City Adolescents in a Weight Management Program
Authors: Alm Mary , Soroudi Nafisseh , Wylie-Rosett Judith , Isasi Carmen R. , Suchday Sonia , Rieder Jessica , Khan Unab
Published: March 2008

Purpose The purpose of this study was (1) to examine the reasons for managing weight, (2) to investigate the barriers and facilitators to achieving behavior goals, and (3) to assess how a behavior coach affects the goalsetting process of obese innercity adolescents in a weight management program.

Methods Obese adolescents participating in a pilot study assessing the role of a behavior coach on successful weight management (n = 18) were interviewed to identify barriers and facilitators to reaching behavior goals. Data were analyzed using descriptive statistics and the constant comparative method of qualitative analysis.

Results In the rationale for weight control, adolescent girls and boys reported a desire to improve physical appearance and physical conditioning, respectively. Barriers to reaching physical activity goals among girls included unsafe neighborhoods and a negative body image. Maintaining unrealistic behavior and weight goals hindered satisfaction with behavior change and weight loss in both genders. Overall, coaching provided support that helped the obese teens feel more successful in the goalsetting process and address issues related to their disruptive environments.

Conclusions Diabetes educators can include a behavior coach as part of a weight management program to help teens set behavior goals and overcome barriers to reaching behavior goals.