1,721,074 research outputs found
Monitoring of a plug flow reactor using an Immuno-Wavelet hybrid system
No full textCom o passar do tempo a computação e a programação atingiram níveis cada vez mais elevados de sofisticação e de aplicação, permitindo grandes avanços na modelagem matemática de sistemas. O uso de simulações, modelagem e computação inteligente são algumas das diversas técnicas que a indústria 4.0 vem utilizando para gerar produtos e serviços cada vez melhores e de qualidade mais alta. Na indústria química a modelagem e simulação são de enorme importância, pois o uso delas não interfere diretamente no sistema operante, desta forma diversos equipamentos e operações do processo podem ser simulados com uso de softwares próprios para isso ou por meio de modelagem numérica. Enquanto isso uso crescente da computação inteligente vem tornando os processos industriais cada vez mais seguros e eficientes. Uma das abordagens a se utilizar da computação inteligente na indústria e em diversas áreas é o monitoramento de integridade estrutural (SHM) com uso de algoritmos para detecção de falhas. Uma ferramenta muito utilizada para isso são os Sistemas Imunológicos Artificiais (SIA), que são um conjunto de técnicas que aplicam princípios e metáforas do sistema imunológico biológico em ferramentas computacionais e criação de algoritmos. Neste trabalho será feito um modelo numérico de um reator PFR para análise do comportamento frente a mudança de parâmetros de entrada, para em seguida ser desenvolvido um sistema de monitoramento de falhas Imuno-Wavelet, composto por uma ferramenta do SIA: o algoritmo de seleção negativa (NSA) proposto por Forrest et al. (1994); em conjunto com uma transformada de wavelet para detectar mudanças de comportamento no reator.Over time, computing and programming reached increasingly higher levels of sophistication and application, allowing great advances in the mathematical modeling of systems. The use of simulations, modeling and intelligent computing are some of the various techniques that industry 4.0 is using to generate increasingly better and higher quality products and services. In the chemical industry, modeling and simulation are of enormous importance, as their use does not directly interfere with the operating system. Therefore, various equipment and process operations can be simulated using specific software or through numerical modeling. Meanwhile, the increasing use of intelligent computing is making industrial processes increasingly safer and more efficient. One of the approaches to using intelligent computing in industry and in various areas is structural health monitoring (SHM) using algorithms for fault detection. A widely used tool for this is Artificial Immune Systems (AIS), which are a set of techniques that apply principles and metaphors of the biological immune system to computational tools and the creation of algorithms. In this work, a numerical model of a PFR reactor will be created to analyze the behavior when changing input parameters, and then an Immuno-Wavelet failure monitoring system will be developed, composed of an SIA tool: the negative selection algorithm. (NSA) proposed by Forrest et al. (1994); in conjunction with a wavelet transform to detect changes in behavior in the reactor
Chemical industry 4.0: classification of lubricants using the negative selection algorithm
No full textAtualmente, em grande parte das máquinas industriais químicas é necessário aplicar lubrificantes, a fim de garantir o bom funcionamento sem prejudicar a estrutura interna do equipamento; na maioria das vezes, esses lubrificantes utilizados são de base mineral, o que pode acabar não sendo muito vantajoso por não serem recursos renováveis, a partir disso, torna-se importante o estudo de graxas de base vegetal, pois além de mais biodegradáveis e menos tóxicos, podem ter performances tão boas quantos os óleos minerais. A partir disso, o trabalho consiste em estudar as propriedades dos lubrificantes vegetais em comparação aos minerais em questões quanto o funcionamento e eficiência do equipamento com tais graxas e também das manutenções necessárias em função do desgaste que pode ser gerado, por meio de testes tribológicos onde serão captados sinais a partir de análises espectroquímicas nas graxas a fim de quantificar o desgaste proporcionado no equipamento e com auxílio de softwares (Octave e/ou MatLab) foi possível realizar a construção de um Algoritmo de Seleção Negativa dos lubrificantes vegetais, baseando-se nos conceitos de Monitoramento de Integridade Estrutural, o qual auxilia na determinação da vida útil e permite o equipamento durar mais tempo, por conta de manutenções preditivas, e também Sistema Imunológico Artificial (SIA), que se baseia em estudos biológicos quanto ao sistema imunológico humano para utilizar uma forma de reconhecer sinais baseado nas análises feitas nos lubrificantes vegetais e comparados com os minerais, isto é demonstrado com gráficos que demonstram o funcionamento do algoritmo, o que permite fazer a devida classificação dos lubrificantes.Nowadays, most chemical industrial machinery requires the use of lubricants in order to guarantee proper functioning without damaging the internal structure of the equipment; most of the time, these lubricants are mineral-based, which can end up not being very advantageous because they are not renewable resources, so it is important to study vegetable-based greases, because in addition to being more biodegradable and less toxic, they can perform just as well as mineral oils. Based on this, the work consists of studying the properties of vegetable lubricants in comparison to mineral lubricants in terms of the operation and efficiency of the equipment with such greases and also the maintenance required due to the wear that can be generated, through tribological tests where signals will be captured from spectrochemical analysis in the greases in order to quantify the wear provided in the equipment and with the help of software (Octave and/or MatLab) it was possible to build a Negative Selection Algorithm for vegetable lubricants, based on the concepts of Structural Integrity Monitoring, which helps determine useful life and allows the equipment to last longer, due to predictive maintenance, and also the Artificial Immune System (AIS), which is based on biological studies of the human immune system to use a way of recognizing signals based on the analyses made on vegetable lubricants and compared to mineral lubricants, this is demonstrated with graphs that show how the algorithm works, which allows the lubricants to be properly classified.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP: 2021/04992-
Control design applied to a non-ideal structural system with behavior chaotic
No full textIn this paper we study the behavior of a structure vulnerable to excessive vibrations caused by an non-ideal power source. To perform this study, the mathematical model is proposed, derive the equations of motion for a simple plane frame excited by an unbalanced rotating machine with limited power (non-ideal motor). The non-linear and non-ideal dynamics in system is demonstrated with a chaotic behavior. We use a State-Dependent Riccati Equation Control technique for regulate the chaotic behavior, in order to obtain a periodic orbit small and to decrease its amplitude. The simulation results show the identification by State-Dependent Riccati Equation Control is very effective. © 2013 Academic Publications, Ltd.Faculty of Engineering of Ilha Solteira Universidade Estadual Paulista (UNESP) Departament of Mathematics, Avenida Brasil, 56, 15385-000, Ilha Solteira, SPFaculty of Engineering of Ilha Solteira Universidade Estadual Paulista (UNESP) Departament of Mathematics, Avenida Brasil, 56, 15385-000, Ilha Solteira, S
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Experimental investigation of vibration attenuation in flexible rotors using shape memory alloys
No full textOs sistemas rotativos estão sujeitos a excitações externas e internas que provocam vibrações indesejáveis, colocando em risco a própria integridade estrutural do sistema e a segurança dos operadores. No âmbito industrial, por exemplo, a atenuação das vibrações pode permitir aos sistemas rotativos, uma operação mais eficiente e segura, proporcionando manutenções periódicas menos frequentes evitando gastos dispendiosos. Neste contexto, o controle de vibrações tem sido objeto de preocupação de inúmeros centros de pesquisa e a literatura especializada é rica em propostas de soluções para esta questão. Este trabalho apresenta uma proposta teórica e experimental de um rotor flexível contendo elementos de liga com memória de forma, cuja finalidade é o aumento da rigidez e geração de amortecimento das vibrações decorrentes de frequências naturais e forças externas, notadamente das forças de desbalanceamento. Este trabalho busca a construção de um conhecimento teórico e particularmente experimental, numa área de pesquisa de domínio restrito e relevância indiscutível.Rotating systems are subject to external and internal excitations that cause undesirable vibrations, jeopardizing the structural integrity of the system and the safety of operators. In the industrial scope, for example, the attenuation of vibrations can allow rotating systems to operate more efficiently and safely, providing less frequent periodic maintenance, and avoiding costly expenses. In this context, vibration control has been the object of concern of numerous research centers, and the specialized literature is rich in proposed solutions to this issue. This work presents a theoretical and experimental proposal for a flexible rotor containing shape memory alloy elements, whose purposes will be to increase stiffness and generate damping of vibrations resulting from external forces, notably unbalanced forces. This work seeks the construction of theoretical and particularly experimental knowledge in a research area of the restricted domain and indisputable relevance.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)CAPES: 001CAPES: 88887.498695/2020-0
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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