827 resultados para systems-based simulation
Resumo:
El presente informe tiene como objetivo presentar los resultados de la práctica profesional en la que se realizó un análisis de la estrategia de quioscos empleada por la Red Pública de Prestación de Servicios al Usuario del Espacio Público (REDEP) del Instituto para la Economía Social (IPES) para la reubicación de vendedores ambulantes en la ciudad de Bogotá. Las ventas ambulantes, se han convertido en una problemática social con importante impacto en la ciudad, sin embargo, la REDEP y sus estrategias son concebidas desde la perspectiva del aprovechamiento económico del espacio público en la ciudad, dejando de lado otras perspectivas y evidenciando una deficiencia en el diseño, implementación y seguimiento de la estrategia de quioscos. Se desarrollaron revisiones documentales para identificar los abordajes predominantes sobre la caracterización de los vendedores informales, la estructura y funcionamiento de la REDEP, las concepciones y lecturas predominantes en las políticas públicas del distrito sobre el fenómeno de las ventas ambulantes, así mismo, se explorarán las conceptualizaciones de pobreza urbana, economía informal y trabajo decente, se describe así mismo el planteamiento de la decisión de permanencia en el sector informal. Se realizaron entrevistas a profundidad estructuradas y semi-estructuradas con los vendedores ambulantes para indagar acerca de las ideas, significados y sentimientos que tienen acerca de su actividad laboral, las interacciones que se dan en el espacio que utilizan, las razones por las que desempeñan esta actividad, sus percepciones y experiencias frente a las intervenciones de los entes del distrito. Se buscó acompañar a vendedores durante jornadas diarias completas para realizar un trabajo de observación etnográfica que permitió hacer triangulación de la información. Se desarrolló también, una revisión documental de fuentes directas e indirectas y principalmente fuentes documentales, que permitieron comprender la configuración de la problemática y la forma en que se ha intervenido desde la estrategia de la REDEP. El documento se fundamenta también en un ejercicio descriptivo equiparable al de seguimiento, ya que se carece del acceso total a evidencias que permitan un ejercicio riguroso de evaluación, el análisis retoma elementos de los sistemas tradicionales basados en cumplimiento y en resultados.
Resumo:
El impacto que ha generado el trauma en Colombia a lo largo de la historia, nos ha obligado a mejorar y adaptar diferentes tipos de sistemas de atención en trauma, basados en los lineamientos internacionales, los cuales buscan evitar el significativo aumento en las tasas de mortalidad y discapacidad que se obtienen de este, especialmente en los servicios de Emergencias en los cuales se reciben el 100% de estos pacientes con traumatismo múltiple o politraumatismo. Dentro de este grupo de pacientes hay un subgrupo que son las pacientes con trauma de abdomen que cursan con estabilidad hemodinámica y además son clasificados de bajo riesgo, ya sea por índices de trauma o por otros métodos como la medición sérica de lactato, los cuales tienen un papel poco despreciable al momento de ver mortalidad y discapacidad por trauma, ya sea penetrante o cerrado; en este trabajo específicamente nos centramos en las personas que consultan al servicio de Emergencias con trauma cerrado de abdomen los cuales son considerados de bajo riesgo, siendo este subgrupo de pacientes uno de los más difíciles de abordar y enfocar al momento de la valoración inicial, ya que se debe tener la seguridad de que no hay lesiones que comprometen la vida y por consiguiente estos pacientes puedan ser dados de alta.
Resumo:
Solar radiation data is crucial for the design of energy systems based on the solar resource. Since diffuse radiation measurements are not always available in the archive data series, either due to the inexistence of measuring equipment, shading device misplacement or missing data, models to generate these data are needed. In this work, one year of hourly and daily horizontal solar global and diffuse irradiation measurements in Évora are used to establish a new relation between the diffuse radiation and the clearness index. The proposed model includes a fitting parameter, which was adjusted through a simple optimization procedure to minimize the Least Square Error as compared to measurements. A comparison against several other fitting models presented in the literature was also carried out using the Root Mean Square Error as statistical indicator, and it was found that the present model is more accurate than the previous fitting models for the diffuse radiation data in Évora.
Resumo:
Forest management is facing new challenges under climate change. By adjusting thinning regimes, conventional forest management can be adapted to various objectives of utilization of forest resources, such as wood quality, forest bioenergy, and carbon sequestration. This thesis aims to develop and apply a simulation-optimization system as a tool for an interdisciplinary understanding of the interactions between wood science, forest ecology, and forest economics. In this thesis, the OptiFor software was developed for forest resources management. The OptiFor simulation-optimization system integrated the process-based growth model PipeQual, wood quality models, biomass production and carbon emission models, as well as energy wood and commercial logging models into a single optimization model. Osyczka s direct and random search algorithm was employed to identify optimal values for a set of decision variables. The numerical studies in this thesis broadened our current knowledge and understanding of the relationships between wood science, forest ecology, and forest economics. The results for timber production show that optimal thinning regimes depend on site quality and initial stand characteristics. Taking wood properties into account, our results show that increasing the intensity of thinning resulted in lower wood density and shorter fibers. The addition of nutrients accelerated volume growth, but lowered wood quality for Norway spruce. Integrating energy wood harvesting into conventional forest management showed that conventional forest management without energy wood harvesting was still superior in sparse stands of Scots pine. Energy wood from pre-commercial thinning turned out to be optimal for dense stands. When carbon balance is taken into account, our results show that changing carbon assessment methods leads to very different optimal thinning regimes and average carbon stocks. Raising the carbon price resulted in longer rotations and a higher mean annual increment, as well as a significantly higher average carbon stock over the rotation.
Resumo:
We trace the evolution of the representation of management in cropping and grazing systems models, from fixed annual schedules of identical actions in single paddocks toward flexible scripts of rules. Attempts to define higher-level organizing concepts in management policies, and to analyse them to identify optimal plans, have focussed on questions relating to grazing management owing to its inherent complexity. “Rule templates” assist the re-use of complex management scripts by bundling commonly-used collections of rules with an interface through which key parameters can be input by a simulation builder. Standard issues relating to parameter estimation and uncertainty apply to management sub-models and need to be addressed. Techniques for embodying farmers' expectations and plans for the future within modelling analyses need to be further developed, especially better linking planning- and rule-based approaches to farm management and analysing the ways that managers can learn.
Monte Carlo simulation of network formation based on structural fragments in epoxy-anhydride systems
Resumo:
A method combining the Monte Carlo technique and the simple fragment approach has been developed for simulating network formation in amine-catalysed epoxy-anhydride systems. The method affords a detailed insight into the nature and composition of the network, showing the distribution of various fragments. It has been used to characterize the network formation in the reaction of the diglycidyl ester of isophthalic acid with hexahydrophthalic anhydride, catalysed by benzyldimethylamine. Pre-gel properties like number and weight distributions and average molecular weights have been calculated as a function of epoxy conversion, leading to a prediction of the gel-point conversion. Analysis of the simulated network further yields other characteristic properties such as concentration of crosslink points, distribution and concentration of elastically active chains, average molecular weight between crosslinks, sol content and mass fraction of pendent chains. A comparison has been made of the properties obtained through simulation with those predicted by the fragment approach alone, which, however, gives only average properties. The Monte Carlo simulation results clearly show that loops and other cyclic structures occur in the gel. This may account for the differences observed between the results of the simulation and the fragment model in the post-gel phase. Copyright (C) 1996 Elsevier Science Ltd.
Resumo:
This paper presents the steps and the challenges for implementing analytical, physics-based models for the insulated gate bipolar transistor (IGBT) and the PIN diode in hardware and more specifically in field programmable gate arrays (FPGAs). The models can be utilised in hardware co-simulation of complex power electronic converters and entire power systems in order to reduce the simulation time without compromising the accuracy of results. Such a co-simulation allows reliable prediction of the system's performance as well as accurate investigation of the power devices' behaviour during operation. Ultimately, this will allow application-specific optimisation of the devices' structure, circuit topologies as well as enhancement of the control and/or protection schemes.
Resumo:
BACKGROUND: Computer simulations are of increasing importance in modeling biological phenomena. Their purpose is to predict behavior and guide future experiments. The aim of this project is to model the early immune response to vaccination by an agent based immune response simulation that incorporates realistic biophysics and intracellular dynamics, and which is sufficiently flexible to accurately model the multi-scale nature and complexity of the immune system, while maintaining the high performance critical to scientific computing. RESULTS: The Multiscale Systems Immunology (MSI) simulation framework is an object-oriented, modular simulation framework written in C++ and Python. The software implements a modular design that allows for flexible configuration of components and initialization of parameters, thus allowing simulations to be run that model processes occurring over different temporal and spatial scales. CONCLUSION: MSI addresses the need for a flexible and high-performing agent based model of the immune system.
Resumo:
The performance of most operations systems is significantly affected by the interaction of human decision-makers. A methodology, based on the use of visual interactive simulation (VIS) and artificial intelligence (AI), is described that aims to identify and improve human decision-making in operations systems. The methodology, known as 'knowledge-based improvement' (KBI), elicits knowledge from a decision-maker via a VIS and then uses AI methods to represent decision-making. By linking the VIS and AI representation, it is possible to predict the performance of the operations system under different decision-making strategies and to search for improved strategies. The KBI methodology is applied to the decision-making surrounding unplanned maintenance operations at a Ford Motor Company engine assembly plant.
Resumo:
In this research the reliability and availability of fiberboard pressing plant is assessed and a cost-based optimization of the system using the Monte- Carlo simulation method is performed. The woodchip and pulp or engineered wood industry in Australia and around the world is a lucrative industry. One such industry is hardboard. The pressing system is the main system, as it converts the wet pulp to fiberboard. The assessment identified the pressing system has the highest downtime throughout the plant plus it represents the bottleneck in the process. A survey in the late nineties revealed there are over one thousand plants around the world, with the pressing system being a common system among these plants. No work has been done to assess or estimate the reliability of such a pressing system; therefore this assessment can be used for assessing any plant of this type.