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Síntese,modelagem e simulação de estruturas neurais morfologicamente realísticas.; Synthesis, Modeling and Simulation of morphologically realistic neural simulation.

Coelho, Regina Célia
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 25/09/1998 Português
Relevância na Pesquisa
788.9962%
Os aspectos morfológicos dos neurônios e estruturas neurais, embora potencialmente importantes, têm recebido relativamente pouca atenção na literatura em neurociência. Este trabalho consiste numa substancial parte de um projeto em desenvolvimento no Grupo de Pesquisa em Visão Cibernética voltado para o estudo da relação formal/função neural. Mais especificamente, o presente trabalho dedica particular atenção para a síntese, modelagem e simulação de estruturas neurais morfologicamente realísticas. A tese se inicia com revisões bibliográficas sobre visão biológica e neurociência, direcionadas aos assuntos a serem aqui abordados. Começamos a descrição dos desenvolvimentos com um levantamento, avaliação e proposta de medidas neuromorfométricas adequadas para exprimir as propriedades mais representativas para nosso trabalho, tais como cobertura espacial, complexidade e decaimento eletrônico. Incluímos nessa parte a metodologia utilizada para a geração de neurônios artificiais bidimensionais estatisticamente semelhantes aos naturais. Apresenta-se também a extensão desta metodologia para o caso tridimensional, validada pela análise neuroinorfométrica dos neurônios gerados. Na seqüência, descrevemos o processo de geração de estruturas neurais compostas de neurônios. Considerando modelos com uma camada neural para a codificação de especificidade de orientação...

Modelagem e simulação de processo descontinuo de recobrimento de particulas em leito de jorro; Modeling and simulation of discontinuous process of particles coating in spouted bed

Mario Paulo Filho
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 05/07/2005 Português
Relevância na Pesquisa
790.2197%
A técnica do leito de jorro apresenta larga utilização nos processos de recobrimento de partículas sólidas, para se obter produtos com propriedades superficiais modificadas, em setores industriais como o agrícola, farmacêutico e de alimentos. Neste trabalho, utilizou-se modelagem matemática e simulação numérica em processo de recobrimento por batelada, aplicando-se as equações do balanço populacional. Posteriormente, o sistema de equações diferenciais obtido foi resolvido pelo método numérico de Runge-Kutta-Fehlberg, utilizando-se software Maple ?8 POT. Marca registrada?. Para a verificação dos resultados da simulação foram obtidos dados experimentais, em escala de laboratório, em um equipamento que consiste em um leito cone-cilíndrico, com um bico atomizador conectado, acoplado a um conjunto soprador e aquecedor de ar. Uma carga de partículas tipo esfera de vidro polidispersas, preparadas a partir da mistura de lotes de partículas de diversos tamanhos, foi colocada no leito de jorro, onde um bico atomizador pulveriza uma suspensão aquosa à base de hidroxietilcelulose. Um planejamento experimental, totalizando 11 experimentos, foi definido variando-se a temperatura do ar de jorro, vazão da suspensão de recobrimento e pressão do ar de atomização. Como variáveis de resposta...

Modelagem e simulação do processo de absorção reativa de CO2 em modulos de membrana; Modeling and simulation of the reactive absorption process in membrane modules

Anderson Gomes
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 07/12/2007 Português
Relevância na Pesquisa
797.7681%
A redução dos níveis de dióxido de carbono (CO2) é de suma importância, tanto para o combate à poluição atmosférica proveniente de atividades industriais, como no tratamento de correntes gasosas em processos químicos. O método clássico para captura de CO2 engloba sua absorção reativa em solução de aminas, conduzida em colunas de borbulhamento, spray ou recheio. Porém, desvantagens como a formação de espuma e dispersão de fase constituem problemas operacionais significativos desses processos. Alternativamente, módulos de membrana de fibras ocas seriam equipamentos mais adequados para esse fim, apresentando como vantagens uma grande área interfacial e flexibilidade operacional. Nesse sentido, o presente estudo buscou realizar a simulação do processo de absorção de CO2 em módulos de membrana, utilizando soluções aquosas de2-amino-2-metil-1-propanol (AMP), dietanolamina (DEA) e metildietanolamina (MDEA). A modelagem matemática do sistema utilizou expressões da taxa de reação e equações de balanço de massa diferenciais. A resolução numérico-computacional do modelo foi conduzida mediante aplicação dos métodos de colocação ortogonal e de Michelsen, tendo sido implementada em linguagem Fortran. O processo foi estudado em diversas condições operacionais para a análise de sensibilidade paramétrica e os resultados indicam...

Modelagem e simulação de um reator catalítico de membrana inerte permseletiva a hidrogênio com transferência de calor e massa; Modeling and simulation of a catalytic reactor with a permselective to hydrogen inert membrane with heat and mass transfer

Germano Possani
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 18/02/2011 Português
Relevância na Pesquisa
792.1892%
Dentre os termoplásticos mais utilizados atualmente na indústria, pode-se mencionar o estireno, principal responsável pela produção de plásticos e borrachas. No processo de fabricação de estireno, a principal rota química é por meio da desidrogenação de etilbenzeno, com o hidrogênio como subproduto. A conversão de etilbenzeno nesta reação é em torno de 50,0 %, devido ao equilíbrio termodinâmico. Para deslocar esse equilíbrio e aumentar a produtividade de estireno,foram desenvolvidas novas configurações de reatores, tal como os reatores com membrana. eatores equipados com membranas de paládio fornecem uma seletividade maisalta ao estireno uando comparados com reatores equipados apenas com membranas porosas. Para explorar o otencial desse tipo de reator, modelagens matemáticas foram desenvolvidas a fim de determinar os parâmetros cruciais que regem esses processos. O objetivo deste trabalho foi modelar e simular um reator de leito fixo catalítico, envolto por uma membrana inerte permseletiva ao hidrogênio com transferência de calor e massa, sendo composta por uma camada de aço inoxidável de 1,6 mm de espessura, a qual serviu de suporte para a deposição de um filme de 20 µm de paládio. Para essa modelagem foram utilizados os métodos de Runge-Kutta-Gill para o cálculo das variáveis no sentido axial...

Equacionamento e simulação do processo de polimerização hidrolítica de nylon-6 em um reator semi-batelada; Equating and simulation of the polymerization process of nylon-6 in a semi-batch reactor

Vanessa Ito Funai
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 25/10/2011 Português
Relevância na Pesquisa
797.8389%
Este trabalho apresenta o equacionamento e simulação do processo de polimerização hidrolítica de nylon-6 em um processo semi-batelada a partir do monômero ?-caprolactama e utilizando um terminador de cadeia ácido monofuncional, no caso, o ácido acético. O modelo cinético considerado levou em conta 6 reações, sendo 3 principais, duas reações secundárias que consideram a formação de dímero cíclico no processo e uma de terminação de cadeia. Foram desenvolvidas equações de taxas de reação globais e por componente, balanço de massa das fases líquida e vapor, balanço de energia para o reator e para a jaqueta de resfriamento, transferência de massa e equilíbrio químico. A modelagem matemática levou em conta as duas abordagens mais freqüentemente encontradas na literatura para a polimerização do nylon-6: uma utiliza o método dos momentos para representação da distribuição de peso molecular, enquanto a outra considera as moléculas de polímero como múltiplos grupos funcionais, sendo a modelagem em função desses grupos. Optou-se pelo modelo de contribuição de grupos para a simulação, realizada no simulador de processos Aspen Polymer Plus® e validada a partir de dados experimentais. Por meio de simulação e planejamento experimental...

Product Development Process Modeling Using Advanced Simulation

Cho, Soo-Haeng; Eppinger, Steven
Fonte: MIT - Massachusetts Institute of Technology Publicador: MIT - Massachusetts Institute of Technology
Tipo: Trabalho em Andamento Formato: 102354 bytes; application/pdf
Português
Relevância na Pesquisa
900.664%
This paper presents a product development process modeling and analysis technique using advanced simulation.The model computes the probability distribution of lead time in a resource-constrained project network where iterations take place among sequential, parallel and overlapped tasks. The model uses the design structure matrix representation to capture the information flows between tasks. In each simulation run, the expected durations of tasks are initially sampled using the Latin Hypercube Sampling method and decrease over time as the model simulates the progress of dynamic stochastic processes. It is assumed that the rework of a task occurs for the following reasons: (1) new information is obtained from overlapped tasks after starting to work with preliminary inputs, (2) inputs change when other tasks are reworked, and (3) outputs fail to meet established criteria. The model can be used for better project planning and control by identifying leverage points for process improvements and evaluating alternative planning and execution strategies. An industrial example is used to illustrate the utility of the model.; Center for Innovation in Product Development

Towards Grid-Wide Modeling and Simulation

Xie, Yong; Teo, Yong Meng; Cai, W.; Turner, S. J.
Fonte: MIT - Massachusetts Institute of Technology Publicador: MIT - Massachusetts Institute of Technology
Tipo: Artigo de Revista Científica Formato: 298581 bytes; application/pdf
Português
Relevância na Pesquisa
995.71516%
Modeling and simulation permeate all areas of business, science and engineering. With the increase in the scale and complexity of simulations, large amounts of computational resources are required, and collaborative model development is needed, as multiple parties could be involved in the development process. The Grid provides a platform for coordinated resource sharing and application development and execution. In this paper, we survey existing technologies in modeling and simulation, and we focus on interoperability and composability of simulation components for both simulation development and execution. We also present our recent work on an HLA-based simulation framework on the Grid, and discuss the issues to achieve composability.; Singapore-MIT Alliance (SMA)

Stochastic Modeling and Simulation of Biological Phenomena with Applications in Population Genetics and in Cell Populations

Li, Biao
Fonte: Universidade Rice Publicador: Universidade Rice
Português
Relevância na Pesquisa
811.5659%
Stochastic modeling and simulation play important roles in population genetics, statistical genetics, cell biology, molecular biology and evolutionary theory. This thesis explores four aspects of stochastic modeling and simulation of biological phenomena with applications. Research carried out is focused on two major themes. The first one (Chapters 2 and 3) concerns application of stochastic modeling in genetics, specifically to identify biases in analysis of genetics data. Two problems that are considered are ascertainment bias in estimation of microsatellite diversity in interspecies comparisons, and sample-selection bias in comparing different methods of rare variant analysis. The second theme (Chapters 4 and 5) concerns application of Poisson and branching process models to understand various aspects of cell proliferation, using S-phase labeling. Two model systems are: transient dynamics of proliferation of neurogenic progenitors in mouse brain with emphasis on differentiation and apoptosis, and balanced growth under different assumptions concerning DNA-replication pattern. In the first part, we investigate factors that are influencing the ascertainment bias of microsatellite allele sizes and explore the impact on estimates of mutation rates. Microsatellite loci play an important role as markers for identification...

Event prediction for modeling mental simulation in naturalistic decision making

Kunde, Dietmar
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Português
Relevância na Pesquisa
798.1505%
Nearly all armies of the Western Hemisphere use modeling and simulation tools as an essential part of performing analysis and training their leaders and war fighters. Tremendous resources have been applied to increase the level of fidelity and detail with which real combat units are represented in computer simulations. Current models digress from Lanchester equations used for modeling the big Cold War scenarios towards modeling of individual soldier capabilities and behavior in the post Cold War environment and increasingly important asymmetric warfare scenarios. Although improvements in computer technology support more and more detailed representations, human decision making is still far from being automated in a realistic way. Many "decisions" within a simulation are based on overly simple models and hardly at all on cognitive processes. One cognitive model in naturalistic decision making is the Recognition Primed Decision Model developed by Klein and Associates. It describes how the actual process humans use to come up with decisions in certain situations is radically different from the traditional model of rational decision making. Mental simulation is an essential part of this model in order to picture possible outcomes in the future for potential courses of actions. This research provides a computational model for mental simulation in a combat simulation environment. It generates the look into the near future with a finite Markov Chain as one instance of several possible predictive models. The results of the model are compared with preliminary human experimental data. The experiments show that the model developed performs in the human range with respect to prediction and decisions. This research shows that entities in a combat simulation environment having the capability of looking ahead into the near future based on statistical data perform more realistically than those that just use the information of the present...

Discovery and Reuse of Modeling and Simulation Assets / Paper 10S-SIW-048

Gustavson, Paul; Dumanoir, Paul; Blais, Curtis; Daehler-Wilking, Richard
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Trabalho em Andamento
Português
Relevância na Pesquisa
886.5766%
Approved for public release; distribution is unlimited.; Documents include Paper & Powerpoint Presentation.; The ability to discover existing modeling and simulation (M&S) assets is a critical need for enabling effective reuse and for reducing the duplication of capabilities. Such visibility and accessibility is key to optimizing the investment of the estimated billions of dollars spent on M&S within the Department of Defense (DoD). This paper updates the status of work presented at the SISO 2009 Spring SIW (09S-SIW-076). The DoD M&S Community of Interest (COI) Discovery Metadata Specification (MSC-DMS) version 1.2.1, which provides a common mechanism to catalog a wide variety of M&S resources as metacards, is now publicly available through the DoD Metadata Registry. A formal process has been established to coordinate the MSC-DMS and the closely related specification used by the DoD M&S Catalog. The M&S Catalog provides a common portal with connection to various M&S related repository sources, and is expected to be declared operational in early 2010. In addition, the M&S Catalog will be federated with the DoD Enterprise Catalog, and publish-and-subscribe mechanisms using DoD Net-Centric Enterprise Services (NCES) will be developed. Tools will be developed and technical assistance provided to help sources map their existing data structures to the MSC-DMS...

Process Modeling: A Systems Engineering Tool for Analyzing Complex Systems

Osmundson, John S.; Gottfried, Russell; Kum, Chee Yang; Boon, Lau Hui; Lian, Lim Wei; Patrick, Poh Seng Wee; Thye, Tan Choo
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
805.8023%
The article of record as published may be found at http://dx.doi.org/10.1002/sys.20012; This paper presents a method for performing architectural analyses of complex systems-ofsystems using process modeling. A process is a series of actions undertaken by a system-ofsystems to produce one or more end results, typically products and services. The method applies to systems-of systems whose effectiveness and performance depend strongly on process timelines, such as distributed information systems, logistics systems, and manufacturing and distribution systems. A fundamental tool in this method is the development of a unified modeling language (UML) related view of the system-of-system processes of interest and the subsequent conversion of the UML related view into an end-to-end system-of-systems executable object-oriented simulation model. This method is illustrated by applying process modeling and simulation to analysis of a military systems-of-systems, an expeditionary warfare system envisioned for the 2015à ¢ 2020 time frame. Expeditionary warfare is the operation of an armed force in an area far from a supportable home base and supported by temporarily established means. The U.S. military has conducted expeditionary warfare in the past by building up forces...

Understanding the Dynamics of Software Projects: An Introduction to Software Process Simulation

Houston, Dan X.; Madachy, Raymond
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
905.55695%
The article of record as published may be located at http://dx.doi.org/10.1145/2600821.2600855; Static representations of development processes provide a basis for communication and coordination of work, as well as for planning work. However, they do not provide any information about the actual behavior of a project, including the effects of staffing decisions, quality-inducing activities, delays, resource contentions, and so forth. Software process simulation (SPS) has demonstrated the capability for providing insight to the dynamics of software projects and supporting project management decisions. This tutorial is a SPS introduction that emphasizes practical approaches to modeling and simulation for both researchers and practitioners. We will discuss modeling and simulation, types of simulation, an historical overview of SPS, the disciplines that contribute to successful SPS work, modeling constructs commonly used to represent software development dynamics, and methods for conducting a SPS project.

Modeling Kanban Processes in Systems Engineering

Turner, Richard; Madachy, Raymond; Ingold, Dan; Lane, Jo Ann
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
890.2772%
Systems engineering processes using pull scheduling methods (kanban) are being evaluated with hybrid modeling and simulation. We are assessing integrated systems and software engineering at the enterprise level, where rapid response software development projects incrementally evolve capabilities of existing systems and/or systems of systems. A kanban-based scheduling system was defined and implemented with connected discrete, continuous and agent-based models. We are simulating the process performance vs. traditional methods of sharing systems engineering services across projects, and whether the overall value of the systems of systems over time is increased.; This material is based upon work supported, in whole or in part, by the U.S. Department of Defense through the Systems Engineering Research Center (SERC) under Contract H98230-08-D-0171. SERC is a federally funded University Affiliated Research Center managed by Stevens Institute of Technology.

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.
Português
Relevância na Pesquisa
801.0707%
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

Validating computational human behavior models: consistency and accuracy issues

Goerger, Simon R.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Dissertação Formato: xxii, 316 p. : ill. (some col.), col. maps
Português
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890.6994%
Approved for public release, distribution is unlimited; As leaders of the Department of Defense (DoD) rely more on modeling and simulation (MandS) to provide information on which they base strategic and tactical decisions, the credibility of simulations becomes more important. This credibility is initially gained through the verification, validation, and accreditation process DoD models are required to undergo prior to their use in simulations. The process of validating behavioral models is not well defined, nor is the process extendable to meet requirements for validating the varied and complex behavioral models. Through a series of empirical studies, this research identifies subject matter expert (SME) biases and their effects on consistency and accuracy of results. This research concludes that a SME's bias has a statistically significant effect on subjective assessment of human performance of urban combat skills. To this end, the research demonstrates how the effects of the natural biases of SMEs can be mitigated based on the scale used to assess assessing human behavior representation (HBR) models, providing a more consistent and accurate means of validating HBR models. In doing so, it assists the DoD MandS Community by providing enhancements to face validation procedures for HBR model implementations for future use in DoD legacy and developmental combat models.; Major...

Analysis of the application of modeling and simulation within the Army Operational Test and Evaluation process in support of weapon systems acquisition.

Thurgood, L. Neil
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: x, 77 p.;28 cm.
Português
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1002.98414%
Approved for public release; distribution is unlimited; The purpose of this thesis is to analyze the application of Modeling and Simulation (M&S) within the Army Operational Test and Evaluation (OT&E) process in support of weapon systems acquisition. This thesis considers the Army's current acquisition process, M&S technologies, infrastructure, and policies that guide the Program Manager (PM) in the application of modeling and simulation in operational testing. An analysis of the potential strengths and weaknesses of M&S in addressing OT&E issues is presented. Lessons learned from past OT&E efforts are analyzed for process improvement through M&S applications. The analysis indicates that M&S is a viable tool for assisting the PM in completing OT&E. M&S techniques can assist in test design validation, expand testing in areas of limited resources and environmental concerns, and validate live testing data. From this analysis, a set of recommendations are formulated, indicating where the PM can integrate M&S into the OT&E process; http://archive.org/details/analysisofapplic00thur; Captain, United States Army

Improving Maritime Prepositioning Force (MPF) offloads using modeling and simulation

Thomas, Brandon K.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xxiv, 89 p. : ill. (chiefly col.) ;
Português
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898.97734%
The Marine Corps' Maritime Prepositioning Force (MPF) marries fly-in troops to their gear in an expeditionary environment. The arrival and assembly operation underneath this larger umbrella of MPF Operations proves itself a somewhat chaotic, definitively complex and dynamic logistics operation. From the moment the offload of the ship or ships begins when equipment and rolling stock exit the ships, until it ends as using units sign for their intended equipment, all personnel involved in this process--drivers, assistant drivers, heavy equipment handlers, crane operators, equipment managers--and all equipment involved present a flurry of activity that must be effectively managed, tracked, and optimized. Modeling, Virtual Environments, and Simulation, or MOVES, tools, aid in providing such capability. The creation of a Discrete Event Simulation (DES) using the open-source tool Viskit enables MPF planning, training, and analysis in its ability to portray the effects that size, amount of personnel support, and time have on the operation. Scenario Authoring and Visualization for Advanced Graphical Environments (Savage) comprises an archive of extensible three dimensional (3D) models that, when tied to the DES in an Extensible 3D (X3D) Graphics environment...

Manufacturing Process Modeling and Simulation

MIHALUTA, Marius; MARTIN, Patrick; DANTAN, Jean-Yves
Fonte: CIRP - ICME Publicador: CIRP - ICME
Português
Relevância na Pesquisa
895.4286%
This paper presents a methodology to be employed in the whole process design phase including first and second processing. This methodology consists of a set of steps which are characterised by an independent model. This paper’s objective is to analyse the coherence between the different models and the coherence between the model and the objectives of each step. The final stage is to develop the production plans. The casting process was the first one to be analyzed. Casting models were created using CAD software (Catia V5R17) and imported into the casting simulation environment (Magmasoft). Filling and solidifying processes have been simulated using different casting models in order to optimize the final configuration. The machining process was modeled using the machining features concept and it was simulated using Catia’s Advanced Machining environment. Two machining strategies have been analyzed according to positioning strategies. Process engineering software was used to create the process plans and to analyze the resource allocation.

Nuclear inputs of key iron isotopes for core-collapse modeling and simulation

Nabi, Jameel-Un; Tawfik, Abdel Nasser
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 20/08/2014 Português
Relevância na Pesquisa
789.0994%
From the modeling and simulation results of presupernova evolution of massive stars, it was found that isotopes of iron, $^{54,55,56}$Fe, play a significant role inside the stellar cores, primarily decreasing the electron-to-baryon ratio ($Y_{e}$) mainly via electron capture processes thereby reducing the pressure support. The neutrinos produced, as a result of these capture processes, are transparent to the stellar matter and assist in cooling the core thereby reducing the entropy. The structure of the presupernova star is altered both by the changes in $Y_{e}$ and the entropy of the core material. Here we present the microscopic calculation of Gamow-Teller strength distributions for isotopes of iron. The calculation is also compared with other theoretical models and experimental data. Presented also are stellar electron capture rates and associated neutrino cooling rates, due to isotopes of iron, in a form suitable for simulation and modeling codes. It is hoped that the nuclear inputs presented here should assist core-collapse simulators in the process of fine-tuning of the $Y_{e}$ parameter during various phases of presupernova evolution of massive stars. A reliable and accurate time evolution of this parameter is a possible key to generate a successful explosion in modeling of core-collapse supernovae.; Comment: 17 pages...

A Flexsim-based Optimization for the Operation Process of Cold-Chain Logistics Distribution Centre

Zhu,X.; Zhang,R.; Chu,F.; He,Z.; Li,J.
Fonte: UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnológico Publicador: UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnológico
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 Português
Relevância na Pesquisa
897.4535%
With people's increasing concern about food safety, cold-chain logistics distribution centre is playing an important role in preventing food from going bad. Now cold-chain logistics distribution centres have the problems of too much transportation, low degree of automation, unreasonable layout planning, complex distribution process etc. It is important to solve these problems in order to achieve efficient distribution. Firstly the modeling and simulation for the operation process of a fruits and vegetables cold-chain logistics distribution centre by using Flexsim software is realized. Then the paper analyses the preliminary output data and finds out the bottleneck and idle resources. Finally this paper makes adjustments for the system to get a better result which hopes to give a reference for the modeling and simulation for the operation process of other cold-chain logistics distribution centres.