A visual programming system for defining behavior in simulation models of manufacturing systems

A visual programming system is described that allows the modeler full flexibility in defining the behavior of a manufacturing system simulation model. Decision-making behavior of objects in the simulation can be viewed by watching an animation of the system layout, viewing function block diagrams of rules that govern behavior, or noting the progress of an object in carrying out sequences of activities that are pictured as operation networks. Rules, elemental operations and operation networks are structured and associated with particular objects, groups of objects, and locations on the manufacturing system layout. The objective of this system is to reduce the time and expense required to construct and modify models, given that manufacturing system data have been collected.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44229/1/10479_2005_Article_BF02136835.pd

Component-Based Tools for Educational Simulations

e-Learning is an effective medium for delivering knowledge and skills. In spite of improvements in electronic delivery technologies, e-Learning is still a long way away from offering anything close to efficient and effective learning environments. To improve e-Learning experiences, much literature supports simulation based e-Learning. This thesis begins identifying various types of simulation models and their features that induce experiential learning. We focus on designing and constructing an easy-to-use Discrete Event Simulation (DES) tool for building engaging and informative interactive DES models that allow learners to control the models’ parameters and visualizations through runtime interactions. DES has long been used to support analysis and design of complex systems but its potential to enhance learning has not yet been fully utilized. We first present an application framework and its resulting classes for better structuring DES models. However, importing relevant classes, establishing relationships between their objects and representing lifecycles of various types of active objects in a language that does not support concurrency demand a significant cognitive workload. To improve this situation, we utilize two design patterns to ease model structuring and logic representation (both in time and space) through a drag and drop component approach. The patterns are the Delegation Event Model, used for linking between components and delegating tasks of executing and updating active objects’ lifecycles, and the MVC (Model-View-Controller) pattern, used for connecting the components to their graphical instrumentations and GUIs. Components implementing both design patterns support the process-oriented approach, can easily be tailored to store model states and visualizations, and can be extended to design higher level models through hierarchical simulation development. Evaluating this approach with both teachers and learners using ActionScript as an implementation language in the Flash environment shows that the resulting components not only help model designers with few programming skills to construct DES models, but they also allow learners to conduct various experiments through interactive GUIs and observe the impact of changes to model behaviour through a range of engaging visualizations. Such interactions can motivate learners and make their learning an enjoyable experience

Simulación híbrida como núcleo de simulación de aplicaciones gráficas en tiempo real.

RESUMEN Las aplicaciones gráficas en tiempo real siguen un paradigma de simulación con- tinuo acoplado. Este paradigma presenta diversos inconvenientes, entre ellos cabe destacar el bajo aprovechamiento de la potencia de cálculo de la máquina, la im- posibilidad de de¯nir la QoS de cada objeto y mantenerla durante la ejecución o el acoplo de los procesos de todos los objetos del sistema, en particular el acoplo del proceso de visualización del sistema con el resto de procesos. La tesis propone cambiar el paradigma de simulación de estas aplicaciones a un paradigma discreto desacoplado. Este nuevo paradigma permite solucionar los pro- blemas del paradigma anterior. Los objetos de¯nen su propia QoS independiente- mente del resto del sistema, incluso se permite de¯nir diferentes QoS para diferentes aspectos del propio objeto. Entre estos objetos, est¶a el objeto visualizador, destina- do a controlar el proceso de visualización. El objeto visualizador también de¯ne su propia QoS. En el sistema discreto desacoplado cada objeto consume únicamente la poten- cia de cálculo estrictamente necesaria para llevar a cabo su simulación con la QoS de¯nida. Por ello, la potencia de cálculo del sistema se reparte entre los objetos en función de sus necesidades. El sistema puede adaptarse dinámicamente, rede¯niendo la QoS de los objetos en función de las condiciones de la ejecución del sistema. Los objetos pueden degradar o mejorar su comportamiento durante periodos de la ejecución para evitar colapsos del sistema o para mejorar el comportamiento del sistema. ____________________________________________________________________________________________________Real time graphic applications, speci¯cally videogames, follow a paradigm of continuous simulation that couple the simulation phase and the rendering phase. This paradigm can be ine±cient or it can produce incorrect simulations. It has di- sadvantages, some of them are: the inadequate computer power distribution between the graphic application objects, it is not possible to de¯ne the Quality of Service (QoS) of each application object, the object QoS can be maintained during the ap- plication running, the behavior of all the system objects are coupled (speci¯cally the rendering process and the simulation process). The proposal is to change the simulation paradigm of real time graphic ap- plications. The new simulation paradigm is discrete and decoupled. The use of a decoupled discrete paradigm avoids the problems of the continuous coupled para- digm and it avoids incorrect simulations, besides it improves the simulation quality and e±ciency. The discrete simulation paradigm allows to de¯ne a private QoS crite- rion for each aspect of each object in the videogame. The render object is dedicated to control the application render process. The render object de¯nes its own QoS criteria. It is possible to de¯ne a di®erent sampling frequency for each object aspect in the system. The discrete paradigm allows to de¯ne the objects sampling frequency to distribute the computer power adequately among the objects. The computer power consumed executing the application is only the necessary to guarantee the QoS of each object. The system can be adapted dynamically. The objects QoS can be adjusted to the objects requirements and the whole system requirements, the system load or characteristics. This sampling frequency may change dynamically to adapt the QoS of the object aspect to the real computer power. The result obtained is a discrete system that allows a Smart System Degradation and may rede¯ne dynamically the objects aspects QoS. Objects collect system information and use it to adapt its QoS

Historia, evolución y perspectivas de futuro en la utilización de técnicas de simulación en la gestión portuaria: aplicaciones en el análisis de operaciones, estrategia y planificación portuaria

Programa Oficial de Doutoramento en Análise Económica e Estratexia Empresarial. 5033V0[Resumen] Las técnicas de simulación, tal y como hoy las conocemos, comenzaron a mediados del siglo XX; primero con la aparición del primer computador y el desarrollo del método Monte Carlo, y más tarde con el desarrollo del primer simulador de propósito específico conocido como GPS y desarrollado por Geoffrey Gordon en IBM y la publicación del primer texto completo dedicado a esta materia y llamado the Art of Simulation (K.D. Tocher, 1963). Estás técnicas han evolucionado de una manera extraordinaria y hoy en día están plenamente implementadas en diversos campos de actividad. Las instalaciones portuarias no han escapado de esta tendencia, especialmente las dedicadas al tráfico de contenedores. Efectivamente, las características intrínsecas de este sector económico, le hacen un candidato idóneo para la implementación de modelos de simulación con propósitos y alcances muy diversos. No existe, sin embargo y hasta lo que conocemos, un trabajo científico que compile y analice pormenorizadamente tanto la historia como la evolución de simulación en ambientes portuarios, ayudando a clasificar los mismos y determinar cómo estos pueden ayudar en el análisis económico de estas instalaciones y en la formulación de las oportunas estrategias empresariales. Este es el objetivo último de la presente tesis doctoral.[Resumo] As técnicas de simulación, tal e como hoxe as coñecemos, comezaron a mediados do século XX; primeiro coa aparición do computador e o desenvolvemento do método Monte Carlo e máis tarde co desenvolvemento do primeiro simulador de propósito específico coñecido como GPS e desenvolvido por Geoffrey Gordon en IBM e a publicación do primeiro texto completo dedicado a este tema chamado “A Arte da Simulación” (K.D. Tocher, 1963). Estas técnicas evolucionaron dun xeito extraordinario e hoxe en día están plenamente implementadas en diversos campos de actividade. As instalacións portuarias non escaparon desta tendencia, especialmente as dedicadas ao tráfico de contenedores. Efectivamente, as características intrínsecas deste sector económico, fanlle un candidato idóneo para a implementación de modelos de simulación con propósitos e alcances moi variados. Con todo, e ata o que coñecemos, non existe un traballo científico que compila e analiza de forma detallada tanto a historia como a evolución da simulación en estes ambientes portuarios, clasificando os mesmos e determinando como estes poden axudar na análise económica destas instalacións e na formulación das oportunas estratexias empresariais. Este é o último obxectivo da presente tese doutoral.[Abstract] Simulation, to the extend that we understand it nowadays, began in the middle of the 20th century; first with the appearance of the computer and the development of the Monte Carlo method, and later with the development of the first specific purpose simulator known as GPS developed by Geoffrey Gordon in IBM. This author published the first full text devoted to this subject “The Art of Simulation” in 1963. These techniques have evolved in an extraordinary way and nowadays they are fully implemented in different fields of activity. Port facilities have not escaped this trend, especially those dedicated to container traffic. Indeed, the intrinsic characteristics of this economic sector, make it a suitable candidate for the implementation of simulation with very different purposes and scope. However, to the best of our knowelegde, there is not a scientific work that compiles and analyzes in detail both, the history and the evolution of simulation in port environments, contributing to classify them and determine how they can help in the economic analysis of these facilities and in the formulation of different business strategies. This is the ultimate goal of this doctoral thesis