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Aplicação da espectroscopia de infravermelho próximo na caracterização de petróleo: simulação de uma unidade de destilação atmosférica.; Application of near infrared spectroscopy in the characterization of crude petroleum: simulation of an atmospheric distillation unit.

Falla Sotelo, Francisco
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 16/10/2006 PT
Relevância na Pesquisa
46.04%
A contínua mudança na qualidade da carga de alimentação das unidades de destilação atmosférica introduz incertezas na operação do processo de refino. A caracterização precisa do petróleo bruto, cuja composição varia devido à sua natureza intrínseca e às condições de transporte e armazenamento nas refinarias, poderia auxiliar na redução destas incertezas. O processo clássico de caracterização, baseado nas curvas de destilação TBP (True Boiling Point, Ponto de Ebulição Verdadeiro), ainda não permite detectar essas mudanças de modo mais dinâmico, o que reduz a precisão da simulação do processo e, portanto, uma menor confiabilidade nas condições de operação determinadas a partir dela. No Brasil, petróleo pesado é produzido de forma predominante, que é misturado freqüentemente com petróleo leve importado antes do refino. Como conseqüência, nas refinarias brasileiras as características do petróleo mudam em média, a cada três dias, sendo esta taxa de variação incompatível com a determinação das curvas de destilação TBP. A análise SimDis (Simulated Distillation, Destilação Simulada) é atualmente a técnica de laboratório alternativa para aproximar as curvas de destilação. Porém...

Criação do banco de dados, simulação e análise energética do processo de produção do biodiesel de soja, mamona e pinhão manso; Datanbank creation, simulation and energetic analysis of biodiesel production process from soybean, castor and physic nut

Júlio César de Carvalho Miranda
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 28/06/2011 PT
Relevância na Pesquisa
45.96%
O biodiesel é um combustível produzido a partir de fontes renováveis, atóxico e livre de enxofre. Apesar de ser uma alternativa possível aos combustíveis fósseis, os dados relacionados ao biodiesel e principalmente à simulação de processos são escassos. Para que isso fosse superado foi construído a partir de métodos de contribuição de grupos e dados experimentais um banco de dados próprio para a simulação do processo de produção do Biodiesel a partir dos óleos de Soja, Pinhão Manso e Mamona. A partir da composição inicial dos triacilgliceróis presentes nos três óleos foram calculadas propriedades como: Temperatura Crítica, Pressão Crítica, Pressão de Vapor, Energia Livre de Gibbs de Formação Padrão, Entalpia de Formação. Os óleos virtuais foram testados em um mesmo layout de simulação com o objetivo de comparar energeticamente as três fontes de matéria-prima, esse layout promoveu a inserção de um vaso flash para prover o reciclo do etanol para o sistema. Foram testadas também outras duas mudanças de layout de simulação. Nos casos da soja e da mamona, respectivamente, duas colunas de destilação e uma retirada lateral na coluna de destilação. Os resultados obtidos foram de grande significância...

Simulation of electrical distributed energy resources for electrical vehicles charging process strategy

Ferreira, João C.; Trigo, Paulo; Silva, Alberto R.; Coelho, Helder; Afonso, João L.
Fonte: IEEE Publicador: IEEE
Tipo: Conferência ou Objeto de Conferência
Publicado em //2010 ENG
Relevância na Pesquisa
45.97%
This paper presents a simulation platform for control and monitor the Electric Vehicle charging process, based on existing power distribution limitations and Microgeneration capacity. The goal of this research is to simulate the energy consumption and their unexpected behavior, using past experience and taking into account distribution network and home power limitation to find an intelligent charging pattern. This paper proposes a novel approach for this problem based on a simulation platform where stochastic process is adopted to perform unexpected user behavior. This simulation platform can be used to determine the capability of the actual electrical distribution network for supplying energy to the final consumers and for charging the bank of batteries of electrical vehicles, which can occur simultaneously.; Fundação para a Ciência e a Tecnologia (FCT) - Project MIT-PT/EDAM-SMS/0030/2008; MIT-Portugal Program

The role of simulation in business process improvement : difficulties and solutions

Sousa, André Filipe Couto de
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Dissertação de Mestrado
Publicado em //2013 ENG
Relevância na Pesquisa
46.1%
Dissertação de mestrado em Engenharia e Gestão de Sistemas de Informação; Due to the constant pressures that nowadays organizations have to face, they need to constantly redefine and improve their businesses. Consequently, business process improvement initiatives are of uttermost importance to overcome these challenges. Business Process Management can be the answer, as it helps organizations to respond adequately and more quickly to the pressures around them. However, business processes are complex systems involving people, activities and technology under a great dependence, variability and complexity, which makes very difficult to forecast the systems performance and behavior. In this context, computerized simulation can play an important role in business process improvement initiatives. First, business process simulation can be considered as a potential way to evaluate, in a controlled environment, the impact of changes on new or existing business processes, without taking the risks and costs of their implementation; second, it can also be considered as a change management tool since it allows to understand the reasons for changes, thus generating explanations for the decision-making process. However, despite its promises...

Layout and process optimisation : using computer-aided design (CAD) and simulation through an integrated systems design tool

Dias, Luís M. S.; Pereira, Guilherme; Vik, Pavel; Oliveira, José A.
Fonte: Inderscience Publicador: Inderscience
Tipo: Artigo de Revista Científica
Publicado em //2014 ENG
Relevância na Pesquisa
45.99%
The design of production and logistic systems is a process of managing both technical and organisational variants in order to identify the best solution for a given system. This paper discusses design issues of production systems that are applied to an internal logistic system in the automotive industry. As far as the production systems design (PSD) is concerned, three basic classes of software tools usually pertain: computer-aided design (CAD), process simulation, and information systems. However, these software tools have been used with low levels of integration. Vik et al. (2010b, 2010c) proposed integrating these software resources in production systems and developed an advanced tool called integrated design of systems (IDS). The proposed IDS tool involves a wide set of functions for the most common tasks of PSD, from conceptualisation to implementation, including systems analysis (P-Q, cluster, and material flow analysis), automatic generation of simulation models, generation of alternatives for the layout of facilities and factories, material flows display, transportation system design, and iterative buffer size specification. The IDS approach takes advantage of simulation, CAD systems, and their integration. This paper will demonstrate the concept and functionalities of the proposed tool in a real industrial case study.; Fundação para a Ciência e Tecnologia

Stochastic simulation of supercritical fluid extraction processes

Mizutani,F. T.; Costa,A. L. H.; Pessoa,F. L. P.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2000 EN
Relevância na Pesquisa
46.03%
Process simulation involves the evaluation of output variables by the specification of input variables and process parameters. However, in a real process, input data and parameters cannot be known without uncertainty. This fact may limit the utilization of simulation results to predict plant behavior. In order to achieve a more realistic analysis, the procedure of stochastic simulation can be conducted. This technique is based on a large set of simulation runs where input variables and parameters are randomly selected according to adequate probability density functions. The objective of this work is to illustrate the application of a stochastic simulation procedure to the process of fractionation of orange essential oil, using supercritical carbon dioxide in a multistage extraction column. Analysis of the proposed example demonstrates the importance of the stochastic simulation to develop more reliable designs and operating conditions for a supercritical fluid extraction process.

Qualitative vs. quantitative software process simulation modelling: conversion and comparison

Zhang, He; Kitchenham, Barbara; Jeffery, Ross
Fonte: IEEE Computer Society Publicador: IEEE Computer Society
Tipo: Conference item; all_ul_research; ul_published_reviewed; none
ENG
Relevância na Pesquisa
65.95%
peer-reviewed; Software Process Simulation Modeling (SPSM) research has increased in the past two decades. However, most of these models are quantitative, which require detailed understanding and accurate measurement. As the continuous work to our previous studies in qualitative modeling of software process, this paper aims to investigate the structure equivalence and model conversion between quantitative and qualitative process modeling, and to compare the characteristics and performance of these two approaches by modeling and simulating a software evolution process. Following the model conversion scheme, the reference quantitative (SD) model and the corresponding qualitative model become comparable. The results present their different capabilities and interesting perspectives, and further the potential use of qualitative modeling in software process research.

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

Li, Biao
Fonte: Universidade Rice Publicador: Universidade Rice
Relevância na Pesquisa
46.01%
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...

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
Relevância na Pesquisa
66%
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.

Software process simulation modeling : an extended systematic review

Zhang, He; Kitchenham, Barbara; Pfahl, Dietmar
Fonte: Springer-Verlag Publicador: Springer-Verlag
Tipo: Conference item; all_ul_research; ul_published_reviewed; none
ENG
Relevância na Pesquisa
65.94%
peer-reviewed; Software Process Simulation Modeling (SPSM) research has increased in the past two decades, especially since the first ProSimWorkshop held in 1998. Our research aims to systematically assess how SPSM has evolved during the past 10 years in particular whether the purposes for SPSM, the simulation paradigms, tools, research topics, and the model scopes and outputs have changed. We performed a systematic literature review of the SPSM research in two subsequent stages, and identified 156 relevant studies in four categories. This paper reports the review process of the second stage and the preliminary results by aggregating studies from the two stages. Although the load of SPSM studies was dominated in ProSim/ICSP community, the outside research presented more diversity in some aspects. We also perceived an immediate need for refining and updating the reasons and the classification scheme for SPSM introduced by Kellner, Madachy and Raffo (KMR).

STAFFSIM, an interactive simulation for rapid, real time course of action analysis by U.S. Army Brigade Staffs

Bohman, William E.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xi, 112 p.
EN_US
Relevância na Pesquisa
55.96%
Approved for public release; distribution is unlimited; The U.S. Army has fielded a wide range of simulations for tactical units. The purpose of these simulations range from training individual skills to collective training for corps staffs. Currently fielded simulations are not designed for operational use. Most are operated by contract civilian personnel and require fixed base facilities. Furthermore, many of these simulations require extensive lead-time to initiate useable scenarios. When the army rolls to the field, its simulations are left behind. The army's staff planning process places huge cognitive demands unit staffs, often resulting in sub optimal decision making. Simulations can provide a useful tool to help staffs visualize and understand complex time-space relationships and unit interactions. Eliminating the need for these factors to be visualized in the mind's eye allows staffs to focus their cognitive abilities on synchronizing mission plans. This thesis develops a prototype simulation for operational use by brigade staffs. The simulations purpose is course of action analysis as described in the war gaming step of the staff planning process. To be used operationally, the simulation must be easy to use, provide rapid scenario development...

Re-Engineering the alkanolamine absorption process to economize carbon capture

Warudkar, Sumedh
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Thesis; Text Formato: application/pdf
ENG
Relevância na Pesquisa
55.88%
Climate change caused by carbon dioxide (CO2) released from the combustion of fossil fuels threatens to have a devastating impact on human life. Power plants that burn coal and natural gas to produce electricity generate more than half of global CO2 emissions. Separating the CO2 emitted at these large sources of emission, followed by long term storage has been proposed as short to medium term solution to mitigate climate change. Implementation of this strategy called 'Carbon Capture and Storage' would allow the continued use of fossil fuels while simultaneously reduce our CO2 emissions. Technologies such as the alkanolamine absorption process, used to separate CO2 from gas mixtures already exist. However, it is presently infeasible to use them for Carbon Capture and Storage due to their relatively large energy consumption. It is estimated that even with the use of state-of-the-art technology, the cost of electricity will increase by around 90%. The research presented in this dissertation is focused on developing novel strategies to limit the increase in the cost of electricity due to implementation of Carbon Capture and Storage. In order to achieve this objective, a process simulation software; ProMax® has been used to optimize the alkanolamine absorption process to suit Carbon Capture application. A wide range of process operating conditions has been analyzed for their effects on energy consumption. Included in this study are process conditions under which waste heat can be utilized for providing energy instead. Based on this analysis...

Modelagem e simulação do processo de fermentação extrativa a vácuo com uma câmara de flash e separação do CO2 utilizando uma coluna de absorção; Modeling and simulation of the vacuum extractive fermentation process using a flash chamber and an absorption column for CO2 separation

Lia Margarita Cohen Paternina
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 07/07/2011 PT
Relevância na Pesquisa
46.04%
O álcool etílico, também conhecido como bioetanol, apresenta características positivas para ser utilizado como combustível em larga escala, como custo relativamente baixo, ser menos poluente quando comparado com os combustíveis de origem fóssil e poder ser produzido a partir de uma matriz renovável por meio da fermentação de produtos de origem vegetal. O processo de fermentação alcoólica convencional é caracteristicamente inibitório, porque o álcool etílico produzido inibe o crescimento das células de leveduras, diminuindo o rendimento do processo. Portanto, o estudo do processo de produção de bioetanol, visando o aumento da eficiência de cada uma das etapas do processo é essencial. Neste contexto, este trabalho tem como objetivo a simulação de um processo de produção de bioetanol baseado no conceito de fermentação extrativa a vácuo, na qual o etanol é retirado do meio fermentativo ao mesmo tempo em que é produzido, permitindo assim, que sua concentração no reator permaneça em níveis baixos durante o processo. Além disso, foi acoplada uma unidade de absorção para recuperação do etanol arrastado pela corrente de gases de fermentação. Este estudo foi realizado no simulador comercial ASPEN PLUS®. Para o cálculo das propriedades termodinâmicas no simulador...

Redesigning the design process through interactive simulation: A case study of life-cycle engineering in jet engine conceptual design

Kerley, Warren; Wynn, David C.; Eckert, Claudia M.; Clarkson, P. John
Fonte: Inderscience Publicador: Inderscience
Tipo: Article; accepted version
EN
Relevância na Pesquisa
56.02%
Post-print; Many aerospace companies are currently making the transition to providing fully-integrated product-service offerings in which their products are designed from the outset with life-cycle considerations in mind. Based on a case study at Rolls-Royce, Civil Aerospace, this paper demonstrates how an interactive approach to process simulation can be used to support the redesign of existing design processes in order to incorporate life-cycle engineering (LCE) considerations. The case study provides insights into the problems of redesigning the conceptual stages of a complex, concurrent engineering design process and the practical value of process simulation as a tool to support the specification of process changes in the context of engineering design. The paper also illustrates how development of a simulation model can provide significant benefit to companies through the understanding of process behaviour that is gained through validating the behaviour of the model using different design and iteration scenarios.; This research was co-funded by the Technology Strategy Board?s Collaborative Research and Development programme (www.innovateuk.org), reference TP/2/IC/6/I/10292, and the IMRC Block Grant. We are also indebted to Dr. Michael Moss and all the other personnel within Rolls-Royce who supported this research.

Analysis of the cyanobacterial hydrogen photoproduction process via model identification and process simulation

Zhang, Dongda; Dechatiwongse, Pongsathorn; Del-Rio-Chanona, Ehecatl Antonio; Hellgardt, Klaus; Maitland, Geoffrey C.; Vassiliadis, Vassilios S.
Fonte: Elsevier Publicador: Elsevier
Tipo: Article; published version
EN
Relevância na Pesquisa
55.97%
This is the final published version. It first appeared at http://www.sciencedirect.com/science/article/pii/S0009250915000883#.; Cyanothece sp. ATCC 51142 is considered a microorganism with the potential to generate sustainable hydrogen in the future. However, few kinetic models are capable of simulating different phases of Cyanothece sp. ATCC 51142 from growth to hydrogen production. In the present study four models are constructed to simulate Cyanothece sp. batch photoproduction process. A dynamic optimisation method is used to determine parameters in the models. It is found that although the piecewise models fit experimental data better, large deviation can be induced when they are used to simulate a process whose operating conditions are different from the current experiments. The modified models are eventually selected in the present study to simulate a two-stage continuous photoproduction process. The current simulation results show that a plug flow reactor (PFR) shows worse performance compared to a continuous stirred-tank reactor (CSTR) in the current operating conditions since it lowers the total hydrogen production. The finding is that nitrate and oxygen concentration change along the direction of culture movement in PFR, and hydrogen is only generated in the zone where both of them are low. The reactor area thereby is not well utilised. Additionally...

Modelling iteration in engineering design

Wynn, David C.; Eckert, Claudia M.; Clarkson, P. John
Fonte: Universidade de Cambridge Publicador: Universidade de Cambridge
Tipo: Conferência ou Objeto de Conferência
EN
Relevância na Pesquisa
45.97%
INTERNATIONAL CONFERENCE ON ENGINEERING DESIGN, ICED?07 28 - 31 AUGUST 2007, CITE DES SCIENCES ET DE L'INDUSTRIE, PARIS, FRANCE; This paper examines design iteration and its modelling in the simulation of New Product Development (NPD) processes. A framework comprising six perspectives of iteration is proposed and it is argued that the importance of each perspective depends upon domain-specific factors. Key challenges of modelling iteration in process simulation frameworks such as the Design Structure Matrix are discussed, and we argue that no single model or framework can fully capture the iterative dynamics of an NPD process. To conclude, we propose that consideration of iteration and its representation could help identify the most appropriate modelling framework for a given process and modelling objective, thereby improving the fidelity of design process simulation models and increasing their utility.

Design project planning, monitoring and re-planning through process simulation

Wynn, David C.; Clarkson, P. John
Fonte: Universidade de Cambridge Publicador: Universidade de Cambridge
Tipo: Conferência ou Objeto de Conferência
EN
Relevância na Pesquisa
55.91%
INTERNATIONAL CONFERENCE ON ENGINEERING DESIGN, ICED'09 24 - 27 AUGUST 2009, STANFORD UNIVERSITY, STANFORD, CA, USA; Effective management of design schedules is a major concern in industry, since timely project delivery can have a significant influence on a company?s profitability. Based on insights gained through a case study of planning practice in aero-engine component design, this paper examines how task network simulation models can be deployed in a new way to support design process planning. Our method shows how simulation can be used to reconcile a description of design activities and information flows with project targets such as milestone delivery dates. It also shows how monitoring and re-planning can be supported using the non-ideal metrics which the case study revealed are used to monitor processes in practice. The approach is presented as a theoretical contribution which requires further work to implement and evaluate in practice.

Model-based approaches to support process improvement in complex product development

Wynn, David C
Fonte: University of Cambridge; Department of Engineering Publicador: University of Cambridge; Department of Engineering
Tipo: Thesis; doctoral; PhD
EN
Relevância na Pesquisa
56.04%
The performance of product development processes is important to the commercial success of new products. The improvement of these processes is thus a strategic imperative for many engineering companies ? the aero-engine is one example of a complex product for which market pressures necessitate ever-shorter development times. This thesis argues that process modelling and simulation can support the improvement of complex product development processes. A literature review identified that design process modelling is a well-established research area encompassing a diverse range of approaches. However, most existing tools and methods are not widely applied in industry. An extended case study was therefore conducted to explore the pragmatic utility of process modelling and simulation. It is argued that iteration is a key driver of design process behaviour which cannot be fully reflected in a mechanistic model. Understanding iteration can help select an appropriate representation for a given process domain and modelling objective. A model-based approach to improve the management of iterative design processes was developed. This approach shows that design process simulation models can support practice despite their limited fidelity. The modelling and simulation framework resulting from this work was enhanced for application to a wider range of process improvement activities. A robust and extensible software platform was also developed. The framework and software tool have made significant contribution to research projects investigating process redesign...

Smooth flexible models of nonhomogeneous Poisson processes fit to one or more process realizations

Deo, Shalaka C.
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
46%
Simulation is a technique of creating representations or models of real world systems or processes and conducting experiments to predict behavior of actual systems. Input modeling is a critical aspect of simulation modeling. Stochastic input models are used to model various aspects of the system under uncertainty including process times and interarrival times. This research focuses on input models for nonstationary arrival processes that can be represented as nonhomogeneous Poisson processes (NHPPs). In particular, a smooth flexible model for the mean-value function (or integrated rate function) of a general NHPP is estimated. To represent the mean-value function, the method utilizes a specially formulated polynomial that is constrained in least-squares estimation to be nondecreasing so the corresponding rate function is nonnegative and continuously differentiable. The degree of the polynomial is determined by applying a modified likelihood ratio test to a set of transformed arrival times resulting from a variance stabilizing transformation of the observed data. Given the degree of polynomial, final estimates of the polynomial coefficients are obtained from original arrival times using least-squares estimation. The method is extended to fit an NHPP model to multiple observed realizations of a process. In addition...

Process simulation for water consumption minimization in pulp mill

Dionísio De Oliveira,K.; Cardoso,M.; Nicolato,R.
Fonte: Latin American applied research Publicador: Latin American applied research
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2010 EN
Relevância na Pesquisa
56%
Reducing the use of fresh water can lead to energy savings when this is properly planned and executed. Chemical process simulation has proven to be an effective tool for performing a global analysis of water systems to identify routes for maximizing the process efficiency concerning to water recovery. System closure has been introduces in pulp mills resulting in simultaneous buildup of non-process elements (NPEs). This buildup generates operational problems in the bleach plant, the biggest consuming stage of water. This paper describes how to use computer simulation tools to carry out a global analysis of a bleach mill plant in Brazil, using WinGEMS and CADSIM simulators, and the NICA-Donnan Model to predict NPE (Mn2+, Fe3+, Mg2+, Ca2+) distribution. Results obtained from simulation in this paper show which changes in the Kraft pulp process in order to implement water savings should be associated to new advanced technologies. The simulated value results for the NICA-Donnan model have been satisfactorily compared with the measurement value. The model made a good description of NPE behavior, and might assist the pulp mill in operating problems caused by the buildup of those elements.