Spelling suggestions: "subject:"raw!"" "subject:"draw!""
21 |
Relationship of human figure drawing with executive functioning and achievement /Miller, Julie M. J. January 2007 (has links)
Thesis (M.S.)--Rochester Institute of Technology, 2007. / Typescript. Includes bibliographical references (leaves 30-36).
|
22 |
Retratos = entre as cores e a materialidade / Portraits : between the color and materialityCarvalho, Saul Ferdinando de Oliveira 17 August 2018 (has links)
Orientador: Luise Weiss / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Artes / Made available in DSpace on 2018-08-17T02:48:04Z (GMT). No. of bitstreams: 1
Carvalho_SaulFerdinandodeOliveira_M.pdf: 20117485 bytes, checksum: f7bef541fa4b7c13503b84f4dc92c950 (MD5)
Previous issue date: 2010 / Resumo: Esta pesquisa tem por finalidade apresentar as determinantes etapas que compõem a produção de um retrato assim como a linguagem poética contida por trás do mesmo. isso será demonstrado através do estudo de alguns dos principais retratistas, dos diferentes retratos já produzidos ao longo da história da arte, e de uma série de retratos produzidos pelo autor desta dissertação. velásquez, Goya, rembrandt, Picasso e lucian Freud são os artistas-chave desta dissertação devido à influência artística exercida sobre os trabalhos aqui apresentados. Foram produzidas pelo autor dessa dissertação uma série de pinturas que tiveram seu processo criativo descrito e comparado à obra dos artistas citados, sendo estes estudados através de bibliografia e de visitas a grandes museus na Europa, a saber, o Museu do Prado, Reina Sofia e Museu Picasso na Espanha, Rijksmuseun e Mauritshuis na Holanda, Museu do Vaticano e Uffizi na Itália, Museu do Louvre e D'Orsay na França entre outros. Verificou-se então que, quanto mais simples as etapas de criação de uma pintura, maior a possibilidade de atingir uma liberdade de expressão, assim como o afeto pelas pessoas retratadas tornou-se fator determinante na conquista de uma maior expressividade na pintura. Vale ressaltar também que um bom retrato evidencia com naturalidade a identidade do retratado em todos os aspectos - físico, emocional, temporal e psicologio - bem como a identidade do próprio retratista, e esta também foi uma preocupação do artista-autor desta dissertação. os retratos elaborados para esta dissertação e aqui apresentados, tiveram a contribuição e direcionamento da Professora Dra. Luise Weiss e também de alguns professores da universidade Complutense de Madrid / Abstract: This research aims to show the crucial steps that make up the production of a portrait as well as poetic language contained behind it. this will be demonstrated through the study of some of the major portrait painters, the various portraits ever produced throughout the history of art, and a series of portraits produced by the author of this dissertation. velazquez, Goya, Rembrandt, Picasso and Lucian Freud are the key artists of this dissertation due to the artistic influence exerted on the work presented here. Were produced by the author of this dissertation a series of paintings that had described his creative process and compared to the work of the artists mentioned above, which were studied through literature and visits to the major museums in Europe, namely, the Prado, Reina Sofia and Picasso Museum in Spain, and Rijksmuseun, Mauritshuis in the Netherlands, the Vatican Museum and the Uffizi in Italy, the Louvre and D'Orsay in France among others. It then emerged that the more simple steps of creating a painting, the greater the chance of achieving freedom of expression as well as the affection for the people portrayed became a determining factor in winning a major expression in painting. It is noteworthy also that a good portrait reveals the identity of naturally portrayed in all aspects - physical, emotional, temporal and psychological - as well as the identity of the portrait itself, and this was also a concern of the artist-author of this dissertation. the pictures generated for this dissertation and here presented, had the assistance and guidance of Profa. Dra. Luise Weiss and also some professors from the university Complutense of Madrid / Mestrado / Artes Cenicas / Mestre em Artes
|
23 |
Desenho instrucional = a ilustração para design da informação : uma proposta didatica para o ensino superior / Instructional design : the illustration for the information design - a didactical proposal for college educationSouza, Ana Cristina Azevedo dos Santos 15 August 2018 (has links)
Orientador: Anna Paula Silva Gouveia / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Artes / Made available in DSpace on 2018-08-15T21:12:48Z (GMT). No. of bitstreams: 1
Souza_AnaCristinaAzevedodosSantos_D.pdf: 7480881 bytes, checksum: 27acb8bcb5abc723b77b8fe9f249bea7 (MD5)
Previous issue date: 2009 / Resumo: Esta tese tem como objetivo de estudo o Desenho Institucional, mais especificamente a ilustração para Design da Informação. Os desenhos contidos em manuais que acompanham produtos industrializados de uso doméstico, sobretudo os de eletrodomésticos de Linha Branca, foram escolhidos para análise examinados segundo parâmetros espaço, Forma, Cor e Expressão, e poderão ser visualizados nestes volumes impressos, no CD-ROM que acompanha a tese ou na internet no endereço http://arquivodigitalaberti.zip.net. As análises experimentais; a "Oficina de Ilustração para Design da Informação" e a disciplina "AP-810 - Tópicos Especiais em Processos Criativos VII - desenho Intrucional", tendo a primeira ocorrido nos anos de 2005 e 2006 no Centro Universitário SENAC e a segunda no Instituto de Artes da Universidade Estadual de Campinas, de março a junho de 2008. Os resultados relativos às reflexões baseadas na teoria da Gestalt, a metodologia de ensino; aplicada nas atividades pedagógicas e outros relatos acerca da produção acadêmico-profissional de alunos que participaram desta pesquisa, integram o texto da tese aqui apresentada / Abstract: This thesis aims at the study of the Institucional Design; more specifically, the illustration for Information Design. The designs in manuals that track the industrialized products for home use, especially those driven to White Line appliances,were chosen for analysis purposes and examined in line with Space,Form,color and Expresion parameters. They may be visualized in these printed volumes in CD-Rom that follows the thesis or in internet address: http://arquivodigitalabert.zip.net . The analyses of the students were developed under my instruction and split into two experimental pedagogical activities: "Oficina de Ilustração para Design da Informação" (Illustration workshop for information Design) and "AP-810- Tópicos especiais em Processos Criativos VIII- Desenho Instructional" (AP-810-A- subject-Special Topics on Creative Processes VIII-Instructional Design).The Farmer took place in 2005 and 20006 at SENAC University Center and the latter at the Art Institute of Campinas State University ,from March to June 2008.Th result related to the reflections based on Gestalt theory, the teaching methodology applied to the pedagogical activities and other accounts linked to academic and professional productivity of the students who took part in this study are embedded in the thesis herein disclosed / Doutorado / Doutor em Artes
|
24 |
En jämförelse mellan teckenbaserade och grafiska lösenord : Fokuserad på användarvänlighet och säkerhetNorlin, Albin January 2016 (has links)
Kontext. För att inte glömma sitt lösenord så väljer användare korta lösenord. Att användare väljer korta lösenord är en säkerhetsrisk som behöver förebyggas. Det finns forskning som pekar på att det är lättare för människor att komma ihåg en bild jämfört med en text. Om grafiska lösenord i form av en bild används istället för teckenbaserade lösenord i form av text skulle användare kunna välja svårare lösenord i form av komplexa lösenordsmönster och samtidigt minska risken att glömma dem. Mål. I projektet utförs en jämförelse mellan teckenbaserade och grafiska lösenord av typen DAS inom områdena användarvänlighet och säkerhet. Inom användarvänlighet så jämförs tiden det tar att registrera samt logga in med ett lösenord av respektive typ. Det jämfördes även hur många lyckade kontra misslyckade inloggningar som gjordes med respektive lösenordstyp. För säkerhet så jämfördes tiden det tar att utföra en lyckad bruteforce-attack mot lösenordssträngarna. Metoder. Den första metoden som användes var en litteraturstudie på vad som tidigare gjorts på området. Litteraturstudien uppföljdes av implementation av två program där det första tillämpade traditionella teckenbaserade lösenord och det andra tillämpade grafiska lösenord av typen DAS. De implementerade programmen användes i experiment med deltagare som gav värden att jämföra och analysera. Resultat. Experimentresultat gav en indikation på att de grafiska lösenorden var bättre i båda aspekterna för användarvänlighet. Liknande indikation gavs för säkerhetsaspekten där även experimentet för de grafiska lösenorden returnerade bättre värde. Det enda värde som pekade för teckenbaserade lösenord var att deltagare av experimentet föredrog de teckenbaserade över grafiska lösenorden. Slutsatser. Det ges en indikation för att grafiska lösenord kan vara mer användarvänliga samt säkrare jämfört med traditionella teckenbaserade lösenord för de aspekter som jämfördes. Det behöver göras fler och större experiment innan det går att fastslå en slutsats om vilken lösenordstyp som är bäst för användarvänlighet samt säkerhet.
|
25 |
Hospitalized children as social actors in the assessment and management of their painKortesluoma, R.-L. (Riitta-Liisa) 10 November 2009 (has links)
Abstract
By acknowledging pain as subjective and only fully perceived by the person in pain, the main aim of this study was to report on the use of qualitative child interviewing and drawings as a research method to elicit hospitalized children’s perceptions and descriptions of their pain experience. Further, the second aim was to contribute to the improvement of pain assessment and management in hospitalized children by approaching the question from the children’s point of view through their words and drawings.
Forty-four children in four paediatric units in a university hospital participated in the study. The data were collected by means of qualitative interviews and thematic drawings. The interview data were analysed using inductive content analysis. The drawings were sorted into categories on the basis of contents, and cognitive competence and emotional disturbances by the Draw-A-Person procedure, and a comparison was made of the data from hospitalized children and healthy control groups.
All the children had experienced pain in different situations while hospitalized. The pain experiences came from four main sources: 1. pain caused by a diagnosed basic illness, 2. pain caused by medical and diagnostic procedures and basic nursing, 3. pain caused by accidents, and 4. inexplicable pain not caused by a particular illness or injury and imaginary pain. In describing their pain, the children emphasized the multidimensional nature of pain and used a number of self-reported pain words to describe physical and psychic pain, as well as evaluative aspects of pain. The children had difficulties in finding positive aspects about pain. The drawings of the hospitalized children frequently depicted medical procedures, whereas the drawings of the healthy controls depicted more family relations. The hospitalized children showed a lower level of cognitive capacity, whereas the healthy control group children revealed a higher level of emotional disturbance. The variety of children’s responses to pain management suggests that children try and can alleviate their pain. The children reported their expectations of professional help and valued the care and attention provided by significant others.
The findings provide research-based knowledge for carrying out research with children, and for healthcare professionals in their assessment and management of children’s pain in more holistic and child-centred way. Children’s competence to describe their pain supports encouraging their involvement as social actors in pain assessment and management in partnership with health care professionals and significant others. This has to be done with respect for their rights as individuals and the desire to give them a sense of ownership of what happens during hospitalization.
|
26 |
Forward osmosis using organic cationic draw solutions for water recoveryHamad, Mohammed J.A. January 2017 (has links)
Forward Osmosis (FO) is an emerging technology which has potential to operate with minimum energy input. High performance of FO systems depend on the availability of a suitable Draw Solution. Different types of Draw Solutions have been proposed, however; choosing a suitable one is still a developing area within the FO field. There is an urgent need to explore new materials in order to develop an efficient FO system. The current study aims at investigating the performance of three Draw Solutions namely, L-Alanine, DADMAC and PolyDADMAC as osmotic agents for FO. These organic cationic solutions can be used as extraction agents of water from poorer quality organic solutes such as fumaric acid solution produced in a continuous flow microbial fermentation process. The performance of the three Draw Solutions was evaluated by measuring the water flux and reverse solute diffusion at different concentrations. The viability of reconcentration of the diluted Draw Solutions was also investigated using Nanofiltration system. The performance and the efficiency of the Draw Solutions were studied via two separated bench scale systems of FO and Nanofiltration. Both Cellulose Triacetate (CTA) and Thin Film Composite (TFC) aquaporin protein FO membranes were employed under different orientations in FO set up operated for 24 hours or longer. In this study, NF90 membrane was used for reconcentration the Draw Solutions. A series of experiments were conducted to obtain the best water flux and reverse solute diffusion under various influencing operating conditions. The experiments were designed to achieve three objectives, i.e. (i) optimum operating conditions for FO system, (ii) optimum operating conditions for the reconcentration system, and (iii) implementation of the optimum operating conditions of the FO system for water recovery from a fumaric acid solution produced by a simulated industrial fermentation process. In the initial stage, L-Alanine Draw Solution demonstrated that it was the most viable agent for FO. It was established that L-Alanine Solution at 0.085 g/mL concentration achieved the highest initial water flux and the lowest reverse solute diffusion through both CTA and TFC aquaporin protein FO membranes. In the second stage, a Nanofiltration system was proven to be effective in the reconcentration of the diluted L-Alanine Draw Solution. The average rejection of L-Alanine ions achieved by NF90 membrane was 96.00%. Drawing on the previous results, the third stage was used to investigate the viability of the FO system in water recovery from fumaric acid solution produced by continuous microbial fermentation process using L-Alanine as a Draw Solution. The reduction of water content of the fumaric acid solution made it to concentrate by 26.00% and 19.80% in 32_ and 17_, respectively. Consequently, FO technology is an effective way to concentrate a fumaric acid solution produced by continuous microbial fermentation process. Based on the results, it is recommended that LAlanine should be proposed in the FO process according to its reliability and effectiveness as a viable draw agent. TFC aquaporin protein membrane is also recommended to be used in recover the water from fumaric acid solution produced by fermentation processes. Further studies should be done to investigate the viability of FO in water recovery from advanced application such as downstream bioprocessing. / Dissertation (MEng)--University of Pretoria, 2017. / Chemical Engineering / MEng / Unrestricted
|
27 |
Magic Draw įrankio išplėtimas klasių diagramų ir būsenų mašinų derinimo galimybėmis / Extension of Magic Draw tool for reconciliation of class diagrams and state machinesBira, Saulius 16 July 2008 (has links)
Modeliais paremtos architektūros (MDA) technologijos panaudojimo tikslas – automatizuoti kuriamos programų sistemos kuriamų modelių transformavimą ir kodo generavimą. Norint atlikti sukurtų modelių korektišką transformavimą, reikia užtikrinti modelių pilnumą ir suderinamumą tarpusavyje. Šie modeliai aprašomi UML modeliavimo kalba. Magistriniame darbe nagrinėjama nuo platformos nepriklausančio modelio kūrimo stadija, modelio klasių ir būsenų mašinų suderimo galimybės ir būsenų mašinų korektiškumo ir išbaigtumo metodikos. Taip pat bus pateikiamas sprendimas atliktas MagicDraw aplinkoje įskiepio pagalba. / The main goal of Model Driven Architecture (MDA) is the automation of software development process. According this technology, we need to create platform independent model (PIM), after that transform it to platform specific model (PSM); from PSM model we can generate program code. To do that, we need to ensure static and dynamic completeness of PIM. All these models are described using UML modeling language. In this work correctness and completeness of PIM is achieved by analyzing compatibility of class diagrams and state machines, as well as correctness and completeness of state machines themselves. To solve this problem, algorithms were created and implemented in a plug-in for MagicDraw CASE tool.
|
28 |
Design de moda : o caminho para a sustentabilidade /Morales, Marina Única Diaz. January 2006 (has links)
Orientador: Marizilda Menezes dos Santos / Banca: José Carlos Plácido da Silva / Banca: Henrique A. Cunha Júnior / Resumo: O índice de criminalidade e desocupação e desocupação se faz crescente na cidade de Londrina, no que diz respeito à população de baixa renda, ou seja, famílias que apresentam um rendimento salarial inferior a dois salários mínimos. Diante disso, surge a necessidade de se apresentar alternativas ocupacionais para jovens, buscando o desenvolvimento de um perfil mais adequado para o engajamento social, com o desenvolvimento de habilidades específicas que sirvam de diferencial e de motivação para o futuro profissional. Foi proposto o Projeto Reciclar Recriando a Vida, locado no Centro Social Marista Irmão Acácio de Londrina, utilizando como matéria prima o retraço da indústria do vestuário. Com a finalidade da valorização da vida, promoção da auto-estima, produtos de design de moda foram desenvolvidos. Como resultado desta dissertação, a utilização de recursos de linguagem formulou uma metodologia própria adequando ao perfil dos jovens atendidos. O design de moda, o desenho da figura humana e a linguagem de moda promoveram o desenvolvimento de habilidades que favoreceram as mudanças sócio-culturais, buscando uma identidade, o caminho para a sustentabilidade por meio do design social ou tecnologia social. / Abstract: Criminal and unemployment indexes are growing in the city of Londrina, concerning low outcome population, or better, families that receive less thantwo salaries a month. Due to this reality, it is necessary to come up with occupation alternatives to the youth, searching for the development of a profile more adequated with their social engagement, and for the development of specific abilities that could motivate and serve as diferrential skills for their professional future. For all these reasons, it was proposed on Marista Irmão Acácio Social Center, at the city of Londrina, the project "Reciclar Recriando a Vida". Having as objectives the valorization of life and the promotion of self-esteem, the project worked on the creation of fashion draw products. As a result of this work, the utilization of language resources formulated a particular metodology wich was adequated to the profile of young people wich was attended. The fasion draw, the human body draw and the fashion language promoted the development of abilities that favor the social and cultural trends, the search for a identity and the path to the suitable conditions through social draw or social technology. / Mestre
|
29 |
A TEORIA DAS INTELIGÊNCIAS MÚLTIPLAS E SUA RELAÇÃO COM O PROCESSO DE ENSINO E APRENDIZADO DO DESENHO: UM ESTUDO COM ADOLESCENTES / THE MULPLY INTELIGENCE THEORY AND ITS RELATION TO THE TEACHING PROCESS AND THE DRAW´S LEARNING: AN ADOLESCENT STUDY CASEFernandes, Márcia Moreno 29 August 2005 (has links)
This reasearch, along the lines on Education end Arts, had as its main goal to analyze and to verify the development of the Multiple Intelligences of Howard Gardner through the Observational Drawing. Along these lines, we have chosen
three particular Multiple Intelligences (Spatial, Cinestesic-corporal and Personal - intra and interpersonal), among the eight available intelligences. The reason for selecting them is that they are more appropriated in Arts teaching. The research was carried out considering undergraduate students doing the first grade on the Design Faculty in a private university, located in the city of Xanxerê (SC). The qualitative
research was used as the main tool of investigation, supported by school etnography, which relied on active observation, field diary and documental analysis. The data
were collected using the drawings elaborated by the students after each proposal presented by the researcher, as well as photos and notes taken by the researcher and students during the meetings. The results are consistent with the initial expectations, showing the role-played by the drawing in developing the multiple intelligences and presenting the distinct processes taken into account to amplify the personal intelligences, Cinestesic-corporal and spatial. / Esta pesquisa, na linha em Educação e Artes, teve como objetivo analisar e verificar o desenvolvimento das Inteligências Múltiplas de Howard Gardner através
do Desenho de Observação. Nessa perspectiva, preferiu-se trabalhar a partir de três das oito Inteligências Múltiplas (Espacial, Cinestésico-corporal e Pessoais - intra e
interpessoais), pelo fato dessas inteligências serem mais apropriadas ao ensino de Artes. A pesquisa foi desenvolvida com jovens universitários do primeiro semestre do Curso de Design de uma instituição privada de ensino superior localizada no município de Xanxerê (SC). Como meio de investigação foi utilizada a pesquisa qualitativa, tendo como suporte a etnografia escolar efetivada através da observação
participante, diário de campo e análise documental. Os dados foram coletados através de desenhos realizados pelos jovens universitários após cada proposta apresentada pela pesquisadora, fotografias e anotações, tanto dos próprios alunos, como da investigadora no decorrer dos encontros. Os resultados supriram as expectativas desta pesquisa, demonstrando a importância do desenho no desenvolvimento das inteligências múltiplas e apresentando processos diferenciados para ampliar as Inteligências Pessoais, cinestésico-corporal e espaciais.
|
30 |
Étude d'un procédé innovant de contre-collage d'emballages flexibles par des colles thermofusibles / Investigation of an innovative hot melt adhesive-based laminating process for flexible packagingKallel, Achraf 15 June 2015 (has links)
« Revoluflex » est un procédé de contre-collage de films plastiques par l'intermédiaire d'une fine couche d'adhésif thermofusible. Dans ce procédé, l'adhésif fondu est extrudé à travers une filière plate (entrefer ~ 1 mm) puis étiré dans l'air sur une très courte distance (~ 1 mm) à des taux d'étirage très importants (Dr>100) et enfin déposé sur le film plastique primaire. Une pompe à vide, placée au-dessous du film extrudé, permet de stabiliser le procédé et d'empêcher l'admission de bulles d'air entre le film primaire et l'adhésif. Un film plastique secondaire est ensuite déposé sur le film primaire pour former le film complexe. En fonction des paramètres du procédé, plusieurs défauts sont observés. Par exemple, on observe dans certaines conditions des surépaisseurs périodiques dans la couche d'adhésif qui s'apparentent à une instabilité d'étirage appelée Draw Resonance. D'autres défauts qui correspondent plutôt à des déchirures dans le film adhésif sont également observés. Ces défauts représentent un obstacle pour le développement de ce procédé innovant et donc l'enjeu de cette étude consiste à comprendre l'origine de ces défauts afin de pouvoir les supprimer ou, au moins, en différer l'apparition.Pour ce faire, ces défauts ont tout d'abord été caractérisés et leur apparition a été quantifiée en fonction des paramètres du procédé et de la rhéologie de différentes formulations d'adhésif.Des modèles de complexité croissante, tant au niveau de la description cinématique de l'écoulement que de la loi de comportement du polymère, ont été développés. Des modèles membrane Newtonien et viscoélastique à largeur constante où un différentiel de pression est appliqué entre les deux faces du film extrudé constituent une première approche théorique qui rend compte de l'effet de la pompe à vide. La méthode de stabilité linéaire a été utilisée pour prédire le phénomène d'instabilité périodique en fonction du comportement rhéologique et des paramètres du procédé. Notre étude a montré que les résultats de ces modèles membrane sont très influencés par les conditions initiales de l'écoulement. Comme l'hypothèse membrane n'est plus valide à de très courtes distances d'étirage, nous avons développé deux modèles 2D Newtonien qui rendent compte à la fois de l'écoulement dans la filière et au cours de l'étirage. Le premier modèle symétrique ne prend pas en compte l'effet de la pompe à vide mais et a été résolu avec deux approches différentes : une méthode de suivi d'interface couplée à la méthode de stabilité linéaire et une méthode de simulation directe par capture d'interface (méthode Level-Set). Nous avons montré que ces deux méthodes permettent d'obtenir la même solution stationnaire et les mêmes résultats de stabilité. Le deuxième modèle prend en compte le différentiel de pression et a été résolu uniquement par la technique de suivi d'interface couplée à la méthode de stabilité linéaire. Ce modèle 2D permet également de trancher entre les différentes conditions initiales testées avec le modèle membrane.Ces modèles permettent d'expliquer plusieurs phénomènes observés expérimentalement comme l'effet stabilisant du différentiel de pression et de la courte distance d'étirage. De plus, ils mettent en évidence un résultat paradoxal qui est l'effet stabilisant du taux d'étirage dans certaines conditions opératoires. Ils montrent enfin que le différentiel de pression provoque une contrainte très élevée au niveau de la lèvre inférieure de la filière, ce qui peut être une explication des déchirures observés dans la couche de colle. / “Revoluflex” is an innovative laminating process consisting in bonding two plastic films with a thin layer of hot melt adhesive. The molten adhesive is extruded through a flat die (gap ~ 1 mm). Then, it is stretched into the air at very high draw ratio (Dr> 100) over a very short distance (~ 1 mm) and set down on the primary plastic film. A vacuum pump, located beneath the extruded film, stabilizes the process and prevents air bubble intake between the primary and the adhesive film. A secondary plastic film is then laid on the coated primary film to give a laminate. Many defects can be observed as a function of the process parameters such as wavelike instabilities characterized by periodical sustained oscillations in the hot melt adhesive layer. This instability is similar to the “Draw Resonance” instability encountered with classical processes involving the stretching of a molten polymer. Other defects looking like small bubbles, cracks or rips in the adhesive layer are also observed. These defects hinder commercial deployment of the process. The aim of this study is there to understand their origins in order to remove them or at least delay their onset.These defects have first been characterized and their appearance was quantified according to process parameters and adhesive rheology. Several theoretical models of increasing complexity, in terms of flow kinematics and polymer rheology, have been developed. Newtonian and Viscoelastic constant width membrane models involving a pressure differential between the two sides of the extruded film represent a first theoretical approach that accounts for the vacuum pump effect. The linear stability method was used to investigate the influence of adhesive rheological behavior and process parameters on the onset of periodic instabilities. It was shown that the results were highly dependent on the initial flow conditions at die exit. Since the membrane assumption is not valid for very short stretching distances, we developed two Newtonian 2D models accounting for both extrusion and drawing steps. The first one is a symmetric model that does not account for the vacuum pump effect. It was solved using two different approaches: a front-tracking method coupled with linear stability analysis and a direct numerical simulation with interface capturing method (Level set method). It was shown that both methods lead to the same stationary solution and the same stability results. The second model accounts for the pressure differential and it was solved using only the front-tracking method. This latter 2D model enables to check the validity of the initial flow conditions of the membrane model.These models allow us to explain several experimental phenomena such as the stabilizing effect of the pressure differential and the short stretching distance. In addition, they help explaining experimental features which contradict the classical literature on drawing instabilities such as the stabilizing effect of increasing the draw ratio under certain operating conditions. Finally, they show that the pressure differential induces a high stress at the bottom lip of the extrusion die, which may clarify the cracks and rips observed in the adhesive layer.
|
Page generated in 0.0499 seconds