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Extensible Modeling and Simulation Framework (XMSF) Exemplars in Analytic Combat Modeling

Blais, Curtis
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Paper and presentation
Relevância na Pesquisa
36.2%
The Extensible Modeling and Simulation Framework (XMSF) is a composable set of standards, profiles and recommended practices for Web-based modeling & simulation (M&S) (http://www.movesinstitute.org/xmsf/xmsf.html). A number of exemplar prototypes are in progress to demonstrate the ability of XML-based markup languages, Internet technologies and Web Services to enable a new generation of distributed M&S applications to emerge, develop and interoperate, including interoperability with command and control systems. This paper describes work being performed to enhance existing analytical models and tools while serving as proof of concept for XMSF ideas. Key applications include integration of the Naval Simulation System (NSS) with the Simk it open source Discrete Event Simulation library and integration of a variety of models and tools in the Flexible Asymmetric Simulation Technologies (FAST) program. The paper describes work completed, work in progress, and future opportunities.

Profiling analytical combat models using extensible modeling and simulation framework (XMSF) principles

Blais, Curtis L.
Fonte: Monterey, California, Naval Postgraduate School Publicador: Monterey, California, Naval Postgraduate School
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.2%
The Department of Defense (Dod) is engaged in warfighting and institutional transformation for the new millenium. In parallel, the DoD Modeling & Simulation (M&S) community is working to identify and adopt transformational technologies providing direct tactical relevance to warfighters. In 2002, the Defense Modeling and Simulation Office (DMSO) initiated the Extensible Modeling and Simulation Framework (XMSF) program to encourage application of Web technologies and open standards by military M&S planners, managers, developers, and users.

Teaching 3D modeling and simulation: virtual kelp forest case study

Brutzman, Don
Fonte: Monterey, California, Naval Postgraduate School Publicador: Monterey, California, Naval Postgraduate School
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.2%
Two classes of graduate students learning 3D graphics and analytic simulation at the Naval Postgraduate School modeled the three-dimensional (3D) shape, structure, imagery and motion behaviors of plants and animals in the kelp forest exhibit at the Monterey Bay Aquarium. Our intended audience includes educators and students of all ages, scientific users interested in composing models in a 3D Web environment, and the general public. The Virtual Reality Modeling Language (VRML) proved to be an excellent medium for capturing diverse models, composing multiple student efforts, and publishing dynamic results publicly on the Web. By focusing on thoroughly modeling a controlled environment, we produced an exemplar 3D graphics site for modeling larger and more sophisticated underwater domains. This project was successfully demonstrated to numerous new users, including 1000 people during the 1988 National Ocean Fair in Monterey. This ptoject serves as an interesting case study on teaching contemporary computer graphics to university students with a wide range of backgrounds.

Using XMSF Web Services for Joint Modeling and Analysis

Buss, Arnold; Ruck, John; Brutzman, Don
Fonte: Monterey, California: Naval Postgraduate School. Publicador: Monterey, California: Naval Postgraduate School.
Tipo: Article & PowerPoint Presentation
Relevância na Pesquisa
36.2%
Fall 2004 Simulation Interoperability Workshop, Paper Number 21 & PowerPoint Presentation; The elements of SEAPOWER 21...Sea Strike, Sea Shield and Sea Basing...commit the Navy to building, training and operating a force that maximizes the contribution of war winning capabilities in the joint battlespace anytime, anywhere. Tying the three pillars of SEAPOWER 21 together is FORCEnet. FORCEnet is the operational construct and architectural framework for naval warfare in the information age, integrating warriors, sensors, command and control, platforms, and weapons into a networked, distributed and joint combat force. SEAPOWER 21 will be implemented by a Global Concept of Operations that will provide our nation with widely dispersed combat power from platforms possessing unprecedented joint warfighting capabilities. This paper describes the creation of a new analytical modeling capability by bringing together the Naval Simulation System (NSS) for sea strike and CombatXXI for littoral and land warfare modeling. The models are linked by Web services using principles from the Extensible Modeling and Simulation Framework (XMSF). This implementation is an examplar for a transformational framework for design, development, and integration of simulation models.

Joint Modeling and Analysis Using XMSF Web Services

Buss, Arnold H.; Ruck, John
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.2%
Proceedings of the 2004 Winter Simulation Conference, R .G. Ingalls, M. D. Rossetti, J. S. Smith, and B. A. Peters, eds.; This paper describes the creation of a new analytical modeling capability by bringing together the Naval Simulation System (NSS) for sea strike and COMBATXXI for littoral and land warfare modeling. The models are linked by Web services using principles from the Extensible Modeling and Simulation Framework (XMSF). This implementation is an exemplar for a transformational framework for design, development, and integration of simulation models.

Análisis y modelado del comportamiento de lixiviación de metales de sedimentos contaminados en contacto con fugas de CO2 procedentes de sistemas de captura y almacenamiento de carbono (CAC); Analysis and modeling of metal release from contaminated sediment subject to CO2 leakages from carbon capture an storage (CCS) sites

Payán Fraile, María Cruz
Fonte: Universidade de Cantabria Publicador: Universidade de Cantabria
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
36.2%
RESUMEN: La Captura y Almacenamiento de Carbono (CAC)es una técnica objeto de intensivo estudio por la comunidad investigadora internacional debido a su potencial para reducir los gases de efecto invernadero. Es importante evaluar las consecuencias de las potenciales fugas de CO2 de sistemas CAC en sedimentos y en el fondo marino. Los metales y contaminantes orgánicos se liberarían de sedimentos contaminados debido a la acidificación del agua de mar. El objetivo de esta tesis es generar conocimiento sobre los potenciales efectos de fugas de CO2 en sedimentos contaminados de sistemas CAC a través del análisis, modelado y evaluación de la movilidad de metales y Carbono Orgánico Disuelto (COD). Se estudia la caracterización ambiental y físico-química del sedimento y el comportamiento de parámetros globales (pH, conductividad y COD) de ensayos de lixiviación, así como la evaluación y el modelado de la liberación de metales bajo diferentes escenarios de acidificación utilizando ensayos de lixiviación. Los resultados obtenidos en la tesis permiten evaluar la sostenibilidad de la tecnología CAC en diferentes escenarios simulados de acidificación del medio marino.; ABSTRACT: Carbon Capture Storage (CCS) is currently among techniques intensely studies by the international research community for their potential to reduce greenhouse gases. the consequences of potential CO2 leakages from CCS sites into surface sediment and into deep sea are then necessary to be evaluated. Trace metals and organic contaminants would be release from contaminated sediment due to the seawater acidification. the general objective of this thesis is to generate new knowledge about the potential effects of CO2 leakages on contaminated marine sediment in CCs systems by means of the analysis...

Coupling remote sensing bio-optical and three-dimensional hydrodynamic modeling to study the phytoplankton dynamics in a tropical hydroelectric reservoir

Curtarelli, M. P.; Ogashawara, I.; Alcantara, E. H.; Stech, J. L.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 185-198
ENG
Relevância na Pesquisa
36.2%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Processo FAPESP: 2008/57719-9; Processo FAPESP: 2007/08103-2; The goal of this study was to determine the extent to which mixing and stratification processes influence the horizontal surface phytoplankton distribution in a tropical hydroelectric reservoir in Brazil. We used a synergistic approach that combines remote sensing bio-optical empirical and three-dimensional hydrodynamic modeling to represent phytoplankton dynamics. Seasonal differences were evaluated by simulating the bio-optical and the three-dimensional hydrodynamic models for two periods: the austral summer and winter of 2009. The three-dimensional hydrodynamic model simulations showed that the water column was completely mixed during winter; the water column remained stratified during summer. We also noticed a permanent thermocline during the summer between 15 and 25 m in the reservoir. In both seasons, the surface current was wind driven and preferentially directed eastward. The bio-optical model showed that the horizontal surface phytoplankton distribution...

The influence of anisotropy in numerical modeling of orthogonal cutting of cortical bone

Santiuste, Carlos; Rodríguez-Millán, Marcos; Giner, Eugenio; Miguélez, Henar
Fonte: Elsevier Publicador: Elsevier
Tipo: info:eu-repo/semantics/acceptedVersion; info:eu-repo/semantics/article
Publicado em 01/10/2014 ENG
Relevância na Pesquisa
36.2%
Cutting operations in bone are involved in surgical treatments in orthopaedics and traumatology. The importance of guaranteeing the absence of damage in the living workpiece is equivalent in this case to ensuring surface quality. The knowledge in this field is really far from the expertise in industrial cutting of mechanical components. Modeling of bone cutting is a challenge strongly dependent on the accurate modeling of mechanical behaviour of the bone. This paper focuses on modeling of orthogonal cutting of cortical bone. The intrinsic anisotropic nature of the cortical bone that makes it comparable to a composite material is taken into account. The influence of anisotropy is analysed comparing this behaviour with an isotropic approach. It is shown that both chip morphology and temperature are affected by the anisotropy of the cortical bone that acts as a workpiece.; This work was supported by the the Ministry of Economy and Competitiveness of Spain under the Project DPI2011-25999 and DPI2013-46643-R

Employing organizational modeling and simulation to deconstruct the KC-135 aircraft's programmed depot maintenance flight controls repair cell

Paskin, Matthew A.; Trevino, Alice W.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xx, 146 p. ; 28 cm.
Relevância na Pesquisa
36.2%
Joint Applied Project; Approved for public release; distribution is unlimited; This research modeled and simulated the KC-135 aircraft's Programmed Depot Maintenance (PDM) Flight Controls Repair Cell to identify improvement opportunities for greater efficiency within the flight controls repair process. PDM is conducted by the 564th Aircraft Maintenance Squadron, 76th Aircraft Maintenance Group, Oklahoma City Air Logistics Center (OC-ALC), Tinker Air Force Base, Oklahoma. The researchers focused on the repair cell's internal formal and informal communication flows and information processing to evaluate the impact on flight controls repair throughput time. Computational organizational modeling was employed to examine organizational design modifications and their effect on repair cycle-time, project cost, and project risk. The modeling and simulation software used is based upon organizational design theory and information-processing research. To build the baseline organizational model that emulated the actual repair process, the researchers collected data through interviews with repair cell personnel and through observation of the repair process. Modifications called ''interventions" were developed to simulate and analyze organizational design changes. The study concludes with the recommendation of feasible organizational design alternatives for OC-ALC decision-makers to improve the flight controls repair process and throughput time.; Outstanding Thesis; United States Air Force authors

Modeling optical turbulence with COAMPS during two observation periods at Vandenberg AFB

Horne, Jimmy D., Jr.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xviii, 143 p. : col. maps
Relevância na Pesquisa
36.2%
Approved for public release, distribution is unlimited; The objective of this thesis is to investigate the forecastability of optical turbulence using the U.S. Navy's Coupled Ocean Atmosphere Mesoscale Prediction System (COAMPS). First, a detailed synoptic study was performed over the Eastern Pacific region for observation periods in October 2001 and March 2002 to focus on mesoscale features affecting Vandenberg AFB. Second, a modified version of COAMPS version 2.0.16 model output was evaluated to ensure reasonable modeling of the mesoscale. Next, temperature and dewpoint temperature vertical profiles of COAMPS, modified with the Turbulent Kinetic Energy (TKE) Method, were compared with balloon-launched rawinsondes, initially, then with higher resolution thermosondes. Optical turbulence parameters were then calculated from the data and a comparison between synthetic profiles and thermosonde-derived profiles were qualitatively and quantitatively studied. Then the vertical resolution of the model was increased for selected forecasts to determine the potential for forecast improvement.; Lieutenant Commander, United States Navy

Evaluation study of the Tactical Atmospheric Modeling System/Real-Time (TAMS-RT) at NPMOC San Diego

Reiss, Arthur J.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: x, 1 v. (various pagings) p.;28 cm.
EN_US
Relevância na Pesquisa
36.2%
Approved for public release; distribution is unlimited; The U.S. Navy is aggressively pursuing mesoscale atmospheric modeling. The Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS) has been developed by the Naval Research Lab in Monterey, California to meet this task. A forecast system employing COAMPS, called the Tactical Atmospheric Mesoscale System- Real Time (TAMS-RT), is currently being field tested at two of the Navy's major regional weather facilities in Manama, Bahrain and San Diego, California. Mesoscale modeling is a complex process that requires detailed knowledge of mesoscale forcing and responses, as well as a capable data display system to make the best use of this new capability. While the challenge of interpretation of forecasts on the mesoscale has increased, the time available for producing forecasts has, if anything, decreased. Optimal methods of evaluation and display are needed that enable a forecaster to rapidly, yet skillfully complete this process. This thesis illustrates analysis techniques to aid in rapidly evaluating the utility of any given mesoscale forecast and proposes optimal methods for 3-D visualization and interpretation of various weather parameters. Using these techniques and methods...

Graph-based modeling and evolutionary analysis of microbial metabolism

Zhou, Wanding
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Thesis; Text Formato: application/pdf
ENG
Relevância na Pesquisa
36.2%
Microbial organisms are responsible for most of the metabolic innovations on Earth. Understanding microbial metabolism helps shed the light on questions that are central to biology, biomedicine, energy and the environment. Graph-based modeling is a powerful tool that has been used extensively for elucidating the organising principles of microbial metabolism and the underlying evolutionary forces that act upon it. Nevertheless, various graph-theoretic representations and techniques have been applied to metabolic networks, rendering the modeling aspect ad hoc and highlighting the conflicting conclusions based on the different representations. The contribution of this dissertation is two-fold. In the first half, I revisit the modeling aspect of metabolic networks, and present novel techniques for their representation and analysis. In particular, I explore the limitations of standard graphs representations, and the utility of the more appropriate model---hypergraphs---for capturing metabolic network properties. Further, I address the task of metabolic pathway inference and the necessity to account for chemical symmetries and alternative tracings in this crucial task. In the second part of the dissertation, I focus on two evolutionary questions. First...

Experimental guided spherical harmonics based head-related transfer function modeling

Zhang, Mengqiu
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Thesis (PhD); Doctor of Philosophy (PhD)
EN_AU
Relevância na Pesquisa
36.2%
In this thesis we investigate the experimental guided spherical harmonics based Head-Related Transfer Function (HRTF) modeling where HRTFs are parameterized as frequency and source location. We focus on efficiently representing the HRTF variations in sufficient detail by mathematical modeling and the experimental measurements. The goal of this work is towards an optimal functional HRTF modeling taking into account the demands of decreasing the computational cost and alleviating the HRTF interpolation and/or extrapolation in the headphone based binaural systems. To represent HRTF by models, we firstly consider the high variability of HRTFs among individuals caused by the differentiation of the scattering effects of the individual bodies on the sound waves. We conduct a series of statistical analyses on an experimental HRTF database of human subjects to reveal the correlation between the physical features of human beings, especially pinna, head, and torso, and the corresponding HRTFs. The strategy enables us to identify a minimal set of physical features which strongly influence the HRTFs in a direct physical way. We next consider the continuity of the HRTF representation in both spatial and frequency domain. We define a functional HRTF model class in which the HRTF spatial representation has been justified to be well approximated by a finite number of spherical harmonics while HRTF frequency representation remains the focus of this thesis. In order to seek an efficient representation for HRTF frequency portion...

Organizational modeling with a semantic wiki: formalization of content and automatic diagram generation

Ferreira, António Alberto Vares
Fonte: Universidade da Madeira Publicador: Universidade da Madeira
Tipo: Dissertação de Mestrado
Publicado em //2008 ENG
Relevância na Pesquisa
36.2%
A key to maintain Enterprises competitiveness is the ability to describe, standardize, and adapt the way it reacts to certain types of business events, and how it interacts with suppliers, partners, competitors, and customers. In this context the field of organization modeling has emerged with the aim to create models that help to create a state of self-awareness in the organization. This project's context is the use of Semantic Web in the Organizational modeling area. The Semantic Web technology advantages can be used to improve the way of modeling organizations. This was accomplished using a Semantic wiki to model organizations. Our research and implementation had two main purposes: formalization of textual content in semantic wiki pages; and automatic generation of diagrams from organization data stored in the semantic wiki pages.; Orientador: Pedro campos e Co-orientador: David Aveiro

Impacto da modelagem estocastica no processo de caracterização de reservatorios maduros; Impact of the stochastic modeling on mature reservoirs characterization process

Marcio Nunes Normando
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 18/02/2005 PT
Relevância na Pesquisa
36.2%
Uma modelagem geológica consistente é necessária para que se possa avaliar os reservatórios de petróleo. No caso de campos maduros, existe uma expressiva quantidade de óleo remanescente e, muitas vezes, com boa capacidade de ser recuperado. Para tanto, faz-se uso de técnicas geoestatísticas para construção de modelos sólidos que permitam localizar e quantificar essas acumulações de óleo. Sabe-se que no estudo de caracterização de reservatórios a modelagem litológica é uma etapa essencial, pois ela servirá de base e guiará a modelagem das propriedades petrofisicas. Neste trabalho, propõe-se verificar o impacto na modelagem litológica, mais especificamente no volume de fácies reservatórios, utilizando-se determinados algoritmos de simulação estocástica, como: simulação seqüencial indicatriz, simulação gaussiana truncada e simulação plurigaussiana. O estudo englobou desde a etapa de tratamento de dados, com o processo de mudança de suporte, até o estudo de conectividade das fácies reservatório, por meio do algoritmo de Hoshen-Kopelman. Como resultado, foi possível observar que o algoritmo de simulação plurigaussiana mostrou-se com melhor capacidade de reproduzir as características iniciais do reservatório pelo fato de condicionar os resultados à proporção dos litotipos...

User modeling and recommendation strategies for tourism

Coelho, Bruno Ernesto da Silva
Fonte: Instituto Politécnico do Porto. Instituto Superior de Engenharia do Porto Publicador: Instituto Politécnico do Porto. Instituto Superior de Engenharia do Porto
Tipo: Dissertação de Mestrado
Publicado em //2009 ENG
Relevância na Pesquisa
36.2%
Mestrado em Engenharia Informática; Tourism is a privileged area for the application of Artificial Intelligence technologies, namely Decision Support Systems and particularly Recommender Systems. The current state of the art concerning the user role and importance within systems is not cheering. User Modeling is used in a poor and rudimentary fashion, when even present; systems do not make use of all information given by the users, sometimes in a tedious and boring manner. As opposed to community and social-based suggestions, recommendations based on the user itself are far from being perfect and optimally used given its potential. This work has the main purposes of developing a User Modeling platform which acts as the basis for a Recommender System for the tourism area. The developed architecture features a myriad of knowledge representation and reasoning techniques which complement themselves in order to assimilate a coherent, complex and diverse user image. The Recommender System is then the culmination of the collaborative effort performed by all User Modeling building blocks. Besides making use of traditional techniques, such as user interests / preferences, the system also innovates in what concern to misused features or unexplored techniques in the area of tourism...

Agile modeling data warehouse development

Couceiro, Frederico da Silva
Fonte: Instituto Politécnico do Porto. Instituto Superior de Engenharia do Porto Publicador: Instituto Politécnico do Porto. Instituto Superior de Engenharia do Porto
Tipo: Dissertação de Mestrado
Publicado em //2012 ENG
Relevância na Pesquisa
36.2%
Most of the traditional software and database development approaches tend to be serial, not evolutionary and certainly not agile, especially on data-oriented aspects. Most of the more commonly used methodologies are strict, meaning they’re composed by several stages each with very specific associated tasks. A clear example is the Rational Unified Process (RUP), divided into Business Modeling, Requirements, Analysis & Design, Implementation, Testing and Deployment. But what happens when the needs of a well design and structured plan, meet the reality of a small starting company that aims to build an entire user experience solution. Here resource control and time productivity is vital, requirements are in constant change, and so is the product itself. In order to succeed in this environment a highly collaborative and evolutionary development approach is mandatory. The implications of constant changing requirements imply an iterative development process. Project focus is on Data Warehouse development and business modeling. This area is usually a tricky one. Business knowledge is part of the enterprise, how they work, their goals, what is relevant for analyses are internal business processes. Throughout this document it will be explained why Agile Modeling development was chosen. How an iterative and evolutionary methodology...

Molecular Modeling Approaches for Determining Gene Function: application to a Putative Poly-A Binding Protein from Leishmania amazonensis (LaPABP)

Silva-Jr,FP; Veyl,FZ; Clos,J; De Simone,S Giovanni
Fonte: Instituto Oswaldo Cruz, Ministério da Saúde Publicador: Instituto Oswaldo Cruz, Ministério da Saúde
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2002 EN
Relevância na Pesquisa
36.2%
The great expansion in the number of genome sequencing projects has revealed the importance of computational methods to speed up the characterization of unknown genes. These studies have been improved by the use of three dimensional information from the predicted proteins generated by molecular modeling techniques. In this work, we disclose the structure-function relationship of a gene product from Leishmania amazonensis by applying molecular modeling and bioinformatics techniques. The analyzed sequence encodes a 159 aminoacids polypeptide (estimated 18 kDa) and was denoted LaPABP for its high homology with poly-A binding proteins from trypanosomatids. The domain structure, clustering analysis and a three dimensional model of LaPABP, basically obtained by homology modeling on the structure of the human poly-A binding protein, are described. Based on the analysis of the electrostatic potential mapped on the model's surface and conservation of intramolecular contacts responsible for folding stabilization we hypothesize that this protein may have less avidity to RNA than it's L. major counterpart but still account for a significant functional activity in the parasite. The model obtained will help in the design of mutagenesis experiments aimed to elucidate the mechanism of gene expression in trypanosomatids and serve as a starting point for its exploration as a potential source of targets for a rational chemotherapy.

SIMV: An Application of Mathematical Modeling in Ventilator Management

Thomsen, George; Sheiner, Lewis
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 08/11/1989 EN
Relevância na Pesquisa
36.2%
SIMV (simulation and modeling of ventilation) is a quantitative system for the mathematical modeling and simulation of pulmonary function. SIMV has been developed as a part of a project designed to assist physicians managing patients who are in the intensive care unit and who require mechanical ventilation. SIMV provides predictions about a patient's pulmonary function, estimates the patient's physiologic parameters, and optimizes the patient's respiratory status by adjusting the controls of the ventilator. These three tasks are accomplished using standard numerical techniques, which are kept separate from SIMV's domain representation. SIMV communicates with other components of the ventilator-management project through probability distributions of shared physiologic parameters.

Modeling and Simulation in Medicine: The State of the Art

Bergeron, Bryan P.; Greenes, Robert A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 09/11/1988 EN
Relevância na Pesquisa
36.2%
Computer modeling and simulation techniques are playing an increasingly central role in changing both the way medicine is taught and the way it is practiced. Fundamental to the art and science of modeling and simulation is an underlying assumption that insight into system behavior can be developed or enhanced from a model that adequately represents a selected subset of the system's attributes. Simulation design considerations include: the provision of an appropriate user interface; determining optimal simulation complexity; defining a tutorial strategy; selecting authoring tools; assessing hardware requirements; identifying user needs; defining pedagogical goals; verification and validation; and system evaluation. Significant trends in simulation include the development of improved authoring tools, migration to desktop hardware platforms, and integration of simulation techniques with other types of applications.