Дисертації з теми "Extrusion systems"
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Jones, Sylvia Anna. "Extrusion cooking of confectionery systems." Thesis, Cranfield University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310905.
Повний текст джерелаYeung, Anthony Kwok-Fu. "Development of microcellular foam sheet extrusion systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0007/MQ40979.pdf.
Повний текст джерелаWang, Xinting. "NEW SYSTEMS FROM THE FORCED ASSEMBLY CO-EXTRUSION PROCESS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1607104088439343.
Повний текст джерелаZhao, Xiyue. "Modeling and control of freeze-form extrusion fabrication." Diss., Rolla, Mo. : University of Missouri-Rolla, 2007. http://scholarsmine.mst.edu/thesis/pdf/Zhao_09007dcc8043fdb1.pdf.
Повний текст джерелаVita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed April 16, 2008) Includes bibliographical references.
Carvalho, Carlos W. Piler. "Effect of sugar on the extrusion of maize and wheat." Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391651.
Повний текст джерелаRongzhi, Huang. "MULTILAYER CO-EXTRUSION AND TWIN-SCREW COMPOUNDING OF POLYMERIC ELASTOMER SYSTEMS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1404864078.
Повний текст джерелаHenry, William John. "Annelation and pyrolysis reactions of 3-thiabicyclo[3.2.0]heptane-3,3-dioxide ring systems." Thesis, University of Edinburgh, 1987. http://hdl.handle.net/1842/15006.
Повний текст джерелаTabani, Haroon R. "Application of NC machining of complex surfaces to streamlined extrusion dies." Ohio : Ohio University, 1989. http://www.ohiolink.edu/etd/view.cgi?ohiou1182523937.
Повний текст джерелаJeß, Katrin [Verfasser]. "Chitosan-Pellets durch Extrusion, Sphäronisation : Entwicklung eines colon-freisetzenden Systems / Katrin Jeß." Kiel : Universitätsbibliothek Kiel, 2008. http://d-nb.info/1019623632/34.
Повний текст джерелаZhang, Feng. "Hot-melt extrusion as a novel technology to prepare sustained-release dosage forms /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
Повний текст джерелаHong, Feng. "Multivariable predictive control development and application in food extrusion processes /." free to MU campus, to others for purchase, 1999. http://wwwlib.umi.com/cr/mo/fullcit?p9946262.
Повний текст джерелаFan, Jintian. "Bubble growth and starch conversion in extruded and baked cereal systems." Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260706.
Повний текст джерелаApichatwatana, Nutsawadee [Verfasser]. "Hot melt extrusion for the production of controlled drug delivery systems / Nutsawadee Apichatwatana." Berlin : Freie Universität Berlin, 2011. http://d-nb.info/1026069645/34.
Повний текст джерелаMargetson, D. N. "The Physicochemical and Rheological Characterisation of Drug-Polymer Systems Prepared by Hot-Melt Extrusion." Thesis, Queen's University Belfast, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.517548.
Повний текст джерелаRepka, Michael Andrew. "Physical-mechanical and chemical properties of topical films produced by hot-melt extrusion /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
Повний текст джерелаDiagne, Mamadou Lamine. "Modelling and control of systems of conservation laws with a moving interface : an application to an extrusion process." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10098/document.
Повний текст джерелаThis thesis is devoted to the analysis of Partial Differential Equations (PDEs) which are coupled through a moving interface. The motion of the interface obeys to an Ordinary Differential Equation (ODE) which arises from a conservation law. The first part of this thesis concerns the modelling of an extrusion process based on mass, moisture content and energy balances. These balances laws express heat and homogeneous material transport in an extruder by hyperbolic PDEs which are defined in complementary time-varying domains. The evolution of the coupled domains is given by an ODE which is derived from the conservation of mass in an extruder. In the second part of the manuscript, a mathematical analysis has been performed in order to prove the existence and the uniqueness of solution for such class of systems by mean of contraction mapping principle. The third part of the thesis concerns the transformation of an extrusion process mass balance equations into a particular input delay system framework using characteristics method. Then, the stabilization of the moving interface by a predictor-based controller has been proposed. Finally, an extension of the analysis of moving interface problems to a particular class of systems of conservations laws has been developed. Port-Hamiltonian formulation of systems of two conservation laws defined on two complementary time-varying intervals has been studied. It has been shown that the coupled system is a port-Hamiltonian system augmented with two variables being the characteristic functions of the two spatial domains
Zhu, Yijun. "Computational Approach to Defect Reduction in Hot Extrusion and Rolling with Material and Process Uncertainties." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1259773708.
Повний текст джерелаBenzine, Youcef. "Enzymatically triggered polymeric drug delivery systems for colon targeting." Thesis, Lille 2, 2019. http://www.theses.fr/2019LIL2S036.
Повний текст джерелаChronic inflammatory bowel diseases (IBD) today affects close to 200,000 people in France. They are characterized by the inflammation of the wall of a part of the digestive tract. They usually include Ulcerative Colitis and Crohn’s disease. Both are chronic diseases that involve inflammation of the colonic mucosa. The main difference between Crohn’s disease and Ulcerative Colitis is the location and nature of inflammation. Crohn’s disease can affect any part of the GIT from mouth to anus but in most cases attacks the terminal ileum. In contrast, Ulcerative Colitis is restricted to the colon and the rectum. An ideal dosage form should effectively protect the drug in the stomach and small intestine and subsequently release the drug in the colon in a targeted and controlled manner. The objective of this work was to develop new drug delivery systems containing a polysaccharide (pectin, guar gum, inulin ...), which are degradable by the colonic bacteria and a hydrophobic thermoplastic polymer (ethylcellulose, polyurethane, polyvinyl acetate ...), which will reduce the hydrophilicity of the polysaccharide. The technique used for the preparation of these dosage forms is hot-melt extrusion. It is a continuous and free solvent process that allows the manufacturing of a dosage form called "extrudate" by forcing the soften material through an orifice. It has been demonstrated that extrudates based on polyvinyl acetate/polyurethane and inulin can minimize the release of a model active substance in the upper part of GIT due to the hydrophobic properties of polyvinyl acetate. Indeed, these extrudates uptake low amount of water and lose low dry mass upon exposure to media simulating the stomach and the small intestine. However, once in contact with the colonic flora, these systems show a considerable loss of mass due to the degradation of inulin by enzymes secreted by colonic bacteria. In another study, hot melt extrudates based on ethylcellulose blended with different types of polysaccharides (guar gum, inulin, corn starch, maltodextrin, pectin and chitosan) were studied for the development of controlled drug delivery systems. Anhydrous theophylline and diprophylline have been used as model drugs. This study was useful to set the extrusion parameters: temperature 100 °C; screw speed 30 rpm; feed rate 3 cc/min; 30 % dibutyl sebacate as a plasticizer. Importantly, hot melt extrudates based on ethylcellulose:guar gum blends offer an interesting potential as controlled drug delivery systems: They can be prepared at temperatures of about 100 °C, provide broad spectra of drug release patterns (in particular about constant drug release rates). Finally, hot melt extrudates remained stable after 1 year storage at ambient conditions
Ji, Shanzuo. "BIO-INSPIRED POLYMER LENS SYSTEMS FROM MULTILAYERED FILMS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1441292644.
Повний текст джерелаBenhadia, Abrehem M. A. "Evaluation of the critical parameters and polymeric coat performance in compressed multiparticulate systems." Thesis, University of Bradford, 2019. http://hdl.handle.net/10454/17459.
Повний текст джерелаCooke, Fiona Ghina Mary. "Can exosomes be used as drug delivery vesicles?" Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/13657.
Повний текст джерелаDeshmukh, Shivprasad S. "Investigation of injection moulding for novel drug delivery systems. An investigation into the use of injection moulding to produce pharmaceutical dosage forms and to understand the relationship between materials, processing conditions and performance, in particular drug release and stability." Thesis, University of Bradford, 2015. http://hdl.handle.net/10454/14302.
Повний текст джерелаThe thesis is hardbound in two volumes. Volume II starts at Chapter 5, page 135.
Alencar, Rodrigo Gomes de. "Desenvolvimento de comprimidos contendo pellets revestidos para liberação cólon específica de cetoprofeno." Universidade Federal de Goiás, 2014. http://repositorio.bc.ufg.br/tede/handle/tede/4020.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Ketoprofen is a nonsteroidal anti-inflammatory drug used for the treatment of mild to moderate pain in chronic inflammatory conditions. Due to its superior potency ketoprofen can be used in the treatment of inflammatory bowel disease (IBD). The treatment of IBD becomes safer and more effective when the drug is incorporated into colon-specific drug delivery systems. Pellets are multiparticulate solid dosage forms extensively investigated as colon-specific drug delivery systems. Pellets can be introduced into capsules or compressed into tablets. The industrial production of tablets containing pellets has several advantages when compared to the production of capsules. However, the compression of the pellets should not affect the release of the drug and the tablets should quickly disintegrate following administration. Therefore, the aim of this study was to develop tablets containing ketoprofen coated pellets for colon-specific drug release. For this, pellets were produced by extrusion and spheronization technique containing 40% (w / w) ketoprofen. Ketoprofen pellets obtained were coated with two different pH - dependent polymers derived from methacrylic acid (Opadry ® k 94 or Eudragit ® FS 30D) with weight gains of 10 or 20% (w / w). The coated pellets were then compressed under different pellets’ amounts and different compression forces. An extra- granular mixture of lactose and microcrystalline cellulose was used as compression aid. The in vitro release of ketoprofen from the systems obtained was evaluated in Bio Dis ® apparatus. The morphological and physical properties of pellets and tablets were assessed. The Eudragit ® FS 30 D coated pellets with weight gains of 10 or 20% showed higher efficiency of colon-specific delivery (94 %), however, the drug was released slowly and incompletely in conditions mimicking the pH of the colonic region. After compression of the pellets, the efficiency of colon – specific drug delivery was lowered after compression (between 20% and 61%, depending on the formulation). The lowest decrease of colon specific efficiency was observed in formulations containing lower amount of pellets, which also produced disintegrating matrices with potential for use in the topical treatment of IBD.
O cetoprofeno é um antiinflamatório não esteroidal usado para o tratamento de dores leves a moderadas, em condições inflamatórias crônicas. Devido a sua elevada potência antiinflamatória, o cetoprofeno pode ser aproveitado no tratamento das doenças inflamatórias intestinais (DII). O tratamento das DII se torna mais seguro e eficaz quando o fármaco é incorporado em sistemas de liberação cólon-específica. Pellets são formas farmacêuticas multiparticuladas bastante investigadas como sistemas de liberação cólon-específica. Após sua produção, os pellets podem ser inseridos em cápsulas ou comprimidos. A produção industrial de comprimidos contendo pellets apresenta inúmeras vantagens quando comparada ao processo de enchimento de cápsulas. No entanto, a compressão dos pellets não deve afetar as características de liberação do fármaco e os comprimidos formados devem se desintegrar rapidamente. Dessa forma, o objetivo deste trabalho foi desenvolver comprimidos contendo pellets revestidos para liberação cólon-específica de cetoprofeno. Para tanto, foram produzidos pellets contendo 40% (p/p) de cetoprofeno e celulose microcristalina pela técnica de extrusão e esferonização. Os pellets de cetoprofeno obtidos foram revestidos com dois diferentes polímeros pH-dependentes, ambos derivados do ácido metacrílico (Opadry ® 94 k ou Eudragit ® FS 30) com ganhos de massa 10 ou 20% (p/p). Os pellets revestidos foram então comprimidos com diferentes cargas de pellets e submetidos a diferentes forças de compressão, utilizando como adjuvante extra-pellets uma mistura granulada de lactose e celulose microcristalina. A liberação in vitro do cetoprofeno a partir das formas farmacêuticas obtidas foi avaliada em dissolutor Bio Dis aparato III. As caracterizações morfológicas e físicas dos pellets e comprimidos foram conduzidas. Os pellets obtidos por revestimento com Eudragit ® FS 30 D, com ganhos de massa de 10 ou 20%, mostraram elevada eficiência de liberação cólon-específica in vitro (até 94%), no entanto, o fármaco foi liberado de forma lenta e incompleta em meio com pH similar ao encontrado na região colônica. Após a compressão dos pellets, os valores de eficiência de liberação cólon-específica sofreram reduções entre 20% e 61%. A menor diminuição da eficiência de liberação cólon-específica foi observada nas formulações contendo a menor carga de pellets, as quais deram origem à matrizes desintegráveis com potencial para utilização no tratamento tópico das DII.
Deshmukh, Shivprasad Shahajirao. "Investigation of injection moulding for novel drug delivery systems : an investigation into the use of injection moulding to produce pharmaceutical dosage forms and to understand the relationship between materials, processing conditions and performance, in particular drug release and stability." Thesis, University of Bradford, 2015. http://hdl.handle.net/10454/14302.
Повний текст джерелаGasparini, Thiago Manha. "Aperfeiçoamento de um detector de espalhamento de luz laser em baixo ângulo (LALLS in-line) para acompanhamento em tempo real do processo de extrusão." Universidade Federal de São Carlos, 2015. https://repositorio.ufscar.br/handle/ufscar/8865.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
The morphology of extruded multiphase polymer systems is usually assessed through off-line characterization methods such as microscopy, which require much time for sample preparation and analysis of the results. This work aimed to the improvement of an optical detector to measure in real time the morphology of blends and polymeric composites in processing by extrusion, by laser light scattering at low angle (LALLS). Such equipment includes hardware and software and is based on measuring the intensity of light from a laser and is spread across and under the melt flow. The signals are collected by an array 91 of photodetectors sent to a computer, and displayed in real time on a three- dimensional plot of scattered light intensity to form a surface defined by 321 points. When analyzing the scattering profile valuable information can be determined that help to elucidate the morphology of the second phase particles. The LALLS detector was tested on bench using standard samples, which were prepared so that one of its parameters (orientation, second phase concentration, dispersed particle size or type of dispersed particle) were known. This allowed the systematic study of these samples and the detector device validation. Finally, the device was tested in real time on the extrusion process, and under different materials and operating conditions. Thus, the LALLS detector device created by the group was improved making it possible to evaluate in a practical way and in real time polymer blends in solid films and morphology of some blends and polymeric composites during extrusion.
A morfologia de sistemas poliméricos polifásicos é usualmente avaliada através de métodos de caracterização off-line, tal como a microscopia, os quais demandam muito tempo para a preparação das amostras e para a análise dos resultados. Este trabalho teve como principal objetivo o aperfeiçoamento de um detector óptico para medida em tempo real da morfologia de misturas e compostos poliméricos no processamento por extrusão, através do espalhamento de luz laser em baixo ângulo (LALLS). Tal equipamento inclui hardware e software e baseia-se na medida da intensidade da luz que provém de um laser e que é espalhada através do material fundido e sob fluxo. Os sinais são coletados por um arranjo de 91 fotodetectores, enviados a um computador, e apresentados em tempo real num gráfico tridimensional da intensidade de luz espalhada formando uma superfície definida por 321 pontos. Ao se analisar o perfil de espalhamento tem-se valiosas informações que ajudam elucidar a morfologia das partículas de segunda fase presentes. O detector de LALLS foi testado em bancada com o uso de amostras-padrão, as quais foram elaboradas de maneira que um de seus parâmetros (orientação, concentração de segunda fase, tamanho de partícula dispersa ou tipo de partícula dispersa) tivesse sido alterado de forma conhecida. Isso permitiu o estudo sistematizado dessas amostras e a validação do dispositivo detector. Por fim, o dispositivo foi testado em tempo real no processo de extrusão, sob diferentes condições materiais e de operação. Com isso, o dispositivo detector de LALLS criado pelo grupo foi aperfeiçoado possibilitando avaliar-se de forma prática e em tempo real: a morfologia de misturas poliméricas na forma de filmes sólidos e algumas misturas e compostos poliméricos durante a extrusão.
Wang, Weirong. "An integrated automation extrusion die design system." Ohio : Ohio University, 1996. http://www.ohiolink.edu/etd/view.cgi?ohiou1177702152.
Повний текст джерелаDavenport, George Andrew 1965. "A process control system for biomass liquefaction." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/558114.
Повний текст джерелаBates, Lisa. "Analysis of the colour of an intermediate moisture Mailland system." Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308102.
Повний текст джерелаSOARES, Emanuel Pereira. "Determinação experimental e simulação das curvas de distribuição de tempo de residência no processo de extrusão de polímeros." Universidade Federal de Campina Grande, 2016. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1045.
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A medida da Distribuição do Tempo de Residência (DTR) em tempo real durante o processo de extrusão permite realizar uma análise global do desempenho do equipamento (extrusora), proporcionando um melhor conhecimento do comportamento do fluxo do material durante todo o processo. Neste trabalho foi desenvolvido um sistema ótico (hardware e software) para detecção de curvas DTR em tempo real durante a extrusão de polímeros. O sistema de detecção teve sua eficiência validada. Os resultados obtidos sugeriram que o sistema foi capaz de detectar as curvas de DTR com um elevado número de pontos, bem como se mostrou sensível a variação na concentração e no tipo de traçador utilizado; além disso, foi possível confirmar a boa reprodutibilidade das medições o que qualificou o sistema para o levantamento das curvas de DTR em tempo real. Posteriormente, foram avaliados os efeitos nas alterações das variáveis de processamento sobre a forma e os parâmetros das curvas de DTR. Foi possível confirmar que a variação na taxa de alimentação possui uma maior influência sobre as curvas DTR do que a velocidade da rosca, fato este corroborado com a literatura. também constatou-se que as alterações no Índice de Fluidez do material de fluxo afetaram a dispersão (capacidade de mistura) nas curvas de DTR. A eficiência energética do processo de extrusão também foi analisada através do levantamento da energia mecânica dissipada e da energia mecânica especifica, foi apresentada uma correlação destes parâmetros energéticos com o tempo de residencia médio. Neste trabalho também foi utilizado uma ferramenta computacional (WinTXS™) para simular as condições de processamento experimentais; a partir daí realizou-se a comparação entre os dados medidos experimentalmente e os simulados, de modo a estabelecer um grau de concordância entre os mesmos. Os resultados obtidos permitiram comprovar que medição da DTR e a simulação computacional unidimensinal são ferramentas importantes no estudo do processo de extrusão de polímeros.
The measurement of Residence Time Distribution (RTD) in real time during the extrusion process allows a comprehensive analysis of equipment performance (extruder), providing a better understanding of the material flow behavior throughout the process. This work developed an optical system (hardware and software) to detect RTD curves in real time during the extrusion of polymers. The efficiency in the detection system was validated. The results obtained suggest that the system it was able to detect the RTD curves with a large number of points, and is sensitive to variations in the concentration and type of tracer used; furthermore, it was possible to confirm the good reproducibility of the measurements which qualify the system for lifting the RTD curves in real time. subsequently, we evaluated the effects of changes in processing variables on the form and parameters of the RTD curves. It was confirmed that the variation in feed rate has a larger influence on cornering RTD than the speed of the screw, a fact corroborated by the literature. It was also found that the change in Melt Index affect the flow of material dispersion (mixing capacity) in the RTD curves. The energy efficiency of the extrusion process was also analyzed by surveying the dissipated mechanical energy and mechanical energy specifies a correlation is presented these energy parameters with the average residence time. This work also used a computational tool (WinTXS ™) to simulate the processing conditions; there after it conducted a comparison between the experimentally measured and simulated data to establish the degree of agreement there between. Results show evidence that measurement of RTD and unidimensinal computer simulation is important tools in the study of polymer extrusion process.
Ng, Chin Yee. "Extrusion of microcellular plastic using a tandem foaming system : design, fabrication and experimentation." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10283.
Повний текст джерелаSanyal, Yoddhojit 1969. "Synthesis and analysis of a microcellular plastics extrusion system for insulation of fine wires." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50529.
Повний текст джерелаIncludes bibliographical references (leaves 138-140).
This thesis deals with analytical and experimental work performed on the extrusion of microcellular plastics with cell sizes of 20 microns or less and cell densities of about a billion cells per cm3. An analytical model of cell nucleation and cell growth during extrusion was developed. This model predicts the nucleation rate by taking into account Gibbs free energy change due to phase separation, as well as surface energy, in binary systems (such as polymer/gas mixtures). The cell growth kinetics during extrusion is also studied under some limiting cases. The analysis shows that due to the simultaneous occurrence of cell nucleation and cell growth during extrusion, these two phenomena are coupled and compete with each other for the gas dissolved in the polymer. With the aid of this model the important extrusion parameters affecting the microstructure of the foam were identified. An order-of-magnitude prediction of cell size, cell density and foam void fraction were made based on realistic numerical values of these parameters. The next phase of the project consisted of using the analytical model and Axiomatic Design Theory to design a tandem extrusion system for wire coating. Satisfaction of the Independence Axiom showed that the process was controllable. Preliminary analysis of the Information Axiom indicated that the system would be stable. Experiments were performed over a range of conditions to determine their effects on the final wire insulation diameter and capacitance. The experimental results were compared to the analytical predictions to further verify the validity of the model as well as to determine its limitations.
by Yoddhojit Sanyal.
Sc.D.
Ladin, Dmitry. "Study of the rheological properties of polymer/gas solutions based on a foam extrusion system." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0017/MQ49787.pdf.
Повний текст джерелаPatil, Ravi R. (Ravi Ramchandra). "Microcellular processing of fluoropolymers and the design of a microcellular foam extrusion system for wire coating." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/38749.
Повний текст джерелаBRAND-WILLIAMS, WENDY. "Activites antioxydante et antiradicalaire de composes phenoliques et d'extraits vegetaux en systemes modeles et en cuisson-extrusion." Massy, ENSIA, 1996. http://www.theses.fr/1996EIAA0058.
Повний текст джерелаBELKOURA, MOUHSSINE. "Systeme redox et extrusion de protons au niveau du plasmalemme des cellules de catharanthus roseus (l. ) g. Don." Toulouse 3, 1986. http://www.theses.fr/1986TOU30072.
Повний текст джерелаSikka, Himanshu. "A soft sensor system for cycle-to-cycle control of parison length in intermittent l extrusion blow molding /." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82633.
Повний текст джерелаIn this work, a 'soft sensor' for cycle-to-cycle control of parison length is developed. A model for parison swell is proposed where the parameters of the model can be tuned from cycle to cycle to match the experimental parison dimensions. The technique was tested on a real intermittent extrusion blow molding machine where a target parison length was achieved by either adjusting the flow rate of the polymer or the die gap opening.
In this work, we have also proposed a technique for estimation of the average relaxation time using a combination of Carreau and Maxwell models. This technique is based on the observed time for parison swell outside the die, and it finds a relaxation time that closely represents the polydisperse nature of blow molding grade resins. The technique could be extended to estimate multiple relaxation times using a generalized Maxwell model. (Abstract shortened by UMI.)
Nguyen, Thi Trinh Lan. "Extrusion- spheronization of pharmaceutical products : system for the delivery of active ingredients which are poorly soluble by oral route." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF047/document.
Повний текст джерелаImprovement in dissolution of poorly soluble drugs has many challenges.In this thesis, an extrusion-spheronization process was thoroughly studied forimproving dissolubility of drug with nano-emulsion formulation.The aim of the thesis work is to describe the properties and manufacturing processes ofpellets to increase the solubility of poorly soluble active ingredients in water and thus improvetheir bioavailability when administered orally: folic acid (water-insoluble vitamin) andketoprofen (Non-steroidal anti-inflammatory, having anti-inflammatory, analgesic andantipyretic action, class II in the Biopharmaceutical Classification System).This study describes the preparation by extrusion-spheronization, characterisation andin vitro dissolution study of folic acid and ketoprofen pellets. Ketoprofen pellets coated withAcryl-EZE®, Advantia® Performance in a fluid-bed minicoater. The results of the tests showedthe feasibility of the preparation of enteric-coated pellets containing a NSAID and that bycoating the multiparticulate system with either 17.5% Acryl-EZE® 93A92545 or with 12%Advantia® Performance 190024HA49 weight gain, an enteric release of the drug from thepellets can be obtained. The results of dissolution testing indicated that in acidic media, entericfilm coating resulted in a delay in the release of the drug, while no delay was observed in pH6.8 buffer media
Tanwilaisiri, Anan. "Design and fabrication of supercapacitors using 3D printing." Thesis, Brunel University, 2018. http://bura.brunel.ac.uk/handle/2438/16338.
Повний текст джерелаCordeiro, Nara Pereira d'Abreu. "Resistencia ao cisalhamento por extrusão - "push out" - de pinos de fibra de vidro a dentina intra-radicular." [s.n.], 2003. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288200.
Повний текст джерелаTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: o objetivo deste estudo foi avaliar a resistência ao cisalhamento por extrusão (push out) entre a dentina intra-radicular e pinos de fibra de vidro nas regiões cervical, média e apical de raízes utilizando dois sistemas de cimentação adesiva. Foram selecionados vinte pré-molares inferiores unirradiculares recém extraídos por motivos ortodônticos, hígidos e livres de trincas. As coroas dos dentes foram removidas na altura da junção cemento esmalte. As polpas dentais foram removidas através de limas endodônticas e os condutos radiculares foram preparados com brocas de largo nO 5, com 8,Omm de penetração. As raízes foram divididas em dois grupos de 10: Grupo 1- pino fixados com o sistema adesivo autocondicionante ED Primer e cimento resinoso Panavia F; Grupo 2- pinos fixados com o sistema adesivo de frasco único Single Bond e cimento resinoso Rely X. Após a fixação dos pinos, as raízes foram mantidas em estufa a 37°C, por 24 h. A porção mais apical das raízes foi seccionada até a altura em que a raiz apresentasse 8,Omm de comprimento. Em seguida, as raízes foram seccionadas transversalmente e 3 discos de 2,7mm de altura foram obtidas e classificadas segundo a região cervical, média e apical do pino. O ensaio de resistência de união por extrusão foi realizado em máquina de ensaio universal Instron 4411 onde uma haste metálica com ponta ativa de 1,Omm de diâmetro produziu a carga para efetuar o deslocamento do pino do conduto radicular. Os valores médios de resistência de união por extrusão não apresentaram diferenças estatísticas significantes no terço cervical da raiz entre os dois materiais de fixação avaliados. Nas regiões média e apical do conduto, os valores de resistência de união apresentados pelo Sing/e Bond + Re/y X foram superiores e estatisticamente diferentes em relação aos valores apresentados pelo sistema ED Primer + Panavia F (p< 0,05). Para os dois materiais em estudo, não houve diferença estatística quando comparadas as regiões média e cervical do pino, porém apresentaram diferença estatística em relação à região apical (p< 0,05). Após o ensaio de cisalhamento por extrusão, os espécimes foram seccionados no sentido longitudinal para análise em microscopia eletrônica de varredura. A zona de interdifusão adesivo/dentina produzida pelo adesivo de frasco único Sing/e Bond apresentou-se mais espessa do que a zona de interdifusão apresentada pelo adesivo autocondicionante ED Primer. Houve áreas desmineralizadas com presença de túbulos dentinários abertos porém parcialmente preenchidos pela resina em ambos os grupos. Também foram observadas bolhas que variaram de tamanho e forma na camada de cimento junto à área da interface de união e mais constantes no terço apical das raízes. Palavras-chave: pino de fibra de vidro; cimento resinoso; sistema adesivo; resistência de união; "push out
Abstract: The purpose of this study was to evaluate the bond strength between fiber posts cemented in root dentin considering different depths of the roots (cervical, median and apical) and two luting materiais, through push out tests and to examine the integration among these components through scanning electron microscopy. Twenty sound bicuspids, tree trom cracks, extracted for orthodontic reasons, were selected. The crowns were removed at the cement enamel junction. The pulps were removed with endodontic reamers and the first 8,Omm of the canais were shaped with number 5 largo burs. The roots were divided into two groups of 10 each. The roots trom group 1 received fiber posts cemented with the self etching primer ED Primer and the composite resin Panavia F., while the roots of Group 2 received fiber posts cemented with the one bottle adhesive Single Bond and the composite resin Rely X. After the posts cementation, the roots were kept in humidity at 3-,0 C for 24 hours. The most apical part of the roots were sectioned until they were 8.0mm long. After that, the roots were sectioned transversally and three 2.7mm thick sections were obtained: cervical, median and apical. The push out test that evaluated bond strength between luting material and root dentin was carried out on an Instron (4411) testing machine. The specimens were positioned on a steel support platform with the post centered over a 2.0mm hole in the platform. A steel probe 1.0mm in diameter was centered over the post and used to apply force to the test specimens. Data from the push out test revealed no statistically significant differences at the cervical portion of the root between the two cementation systems tested. At the median and apical portion of the root, the bond strength values presented by the Sing/e Bond and Re/y X were superior and statistically different from those presented by ED Primer and Panavia F (P
Dentística
Doutor em Clínica Odontológica
Abramo, Kristin N. "Building the Interphase Nucleus: A study on the kinetics of 3D chromosome formation, temporal relation to active transcription, and the role of nuclear RNAs." eScholarship@UMMS, 2020. https://escholarship.umassmed.edu/gsbs_diss/1099.
Повний текст джерелаLara, Lledó Marta Inés. "Antimicrobial packaging system for minimally processed fruit." Doctoral thesis, Universitat Politècnica de València, 2018. http://hdl.handle.net/10251/61388.
Повний текст джерела[ES] En la presente Tesis Doctoral se han desarrollado materiales de envase activo antimicrobiano, a escala laboratorio y a escala semi-industrial, con el objetivo de reducir la proliferación de la flora natural de la fruta pelada y cortada y extender su vida útil. Se han desarrollo distintos prototipos para su posterior aplicación industrial Previo al desarrollo de los materiales de envase, se ha realizado una selección de agentes activos más idóneos. Para ello se han estudiado mediante ensayos in vitro las propiedades antimicrobianas de agentes activos volátiles, citral, hexanal y linalool y diferentes mezclas de los mismos, frente a distintos microorganismos típicos del deterioro de las frutas, mohos y levaduras, concluyendo que la efectividad de la mezcla de los tres es superior a la suma de la efectividad de los activos de forma individual. Así mismo, también se han seleccionado antimicrobianos no volátiles como el sorbato potásico y benzoato sódico, los cuáles son ampliamente empleados en la industria alimentaria debido principalmente a sus propiedades antifúngicas. Con los agentes activos seleccionados, se han desarrollado películas monocapa de polipropileno (PP) con distintas concentraciones de la mezcla activa, citral, hexanal y linalool, a escala laboratorio, mediante técnicas de extrusión, y películas bicapa a escala semi-industrial con distintos espesores de capa activa mediante coextrusión. Por otra parte, se desarrollaron bandejas activas a escala semi-industrial mediante termoconformado de láminas obtenidas por coextrusión de compuestos de PP y etilvinilaceteto (EVA) con sorbato potásico o benzoato sódico como agentes antimicrobianos. Se han evaluado las propiedades mecánicas, barrera y térmicas de los materiales activos desarrollados, así como su sellabilidad y transparencia. En general, las propiedades de los polímeros no se vieron afectadas de manera relevante. Sin embargo, las bandejas activas perdieron su carácter transparente debido a la incorporación de los agentes activos no volátiles. Se ha estudiado la cinética de liberación de los compuestos activos volátiles y no volátiles a distintas temperaturas, determinando los coeficientes de difusión de los agentes activos mediante el ajuste a modelos matemáticos de difusión basados en la Segunda Ley de Fick. Entre los agentes volátiles, el hexanal mostró un mayor coeficiente de difusión seguido de citral y linalool. Por otra parte, no hubo apenas diferencia en los coeficientes de difusión del sorbato potásico y benzoato sódico, siendo éstos del mismo orden de magnitud. Igualmente, se han realizado diferentes experimentos in vitro a distintas temperaturas para determinar las propiedades antimicrobianas de los materiales desarrollados. En general, los materiales activos presentan una elevada capacidad antimicrobiana que se ve potenciada al aumentar la temperatura de exposición. Una vez evaluadas las características de los materiales desarrollados, se han efectuado ensayos de envasado de naranja y piña pelada y cortada con las películas y las bandejas activas y con la combinación del sistema de envase bandeja activa termosellada con la película activa. En general, el sistema de envase activo mejoró la conservación de la fruta por un mayor tiempo, entre 2 y 7 días para la naranja y piña, respectivamente, presentando una gran capacidad antimicrobiana y manteniendo los parámetros de calidad de la fruta en niveles estables por un mayor tiempo. Por último, se ha estudiado la seguridad de estos materiales de acuerdo a la legislación de materiales en contacto con alimentos y la legislación alimentaria europea, concluyendo que los materiales activos desarrollados no presentan preocupación para la seguridad de los consumidores.
[CAT] En la present Tesi Doctoral s'han desenvolupat materials d'envasament actiu antimicrobià, a escala de laboratori i a escala semi-industrial amb l'objectiu de reduir la proliferació de la flora natural de la fruita pelada i tallada i estendre la seua vida útil. S'han desenvolupament diferents prototips per a la seua posterior aplicació industrial. Previ al desenvolupament dels materials actius, s'han seleccionat els agents actius mes idonis estudiant mitjançant assajos in vitro les propietats antimicrobianes d'agents actius volàtils, citral, hexanal i linalool i diferents mescles dels mateixos, enfront de diferents microorganismes típics de la deterioració de les fruites -floridures i llevats- concloent que l'efectivitat de la mescla dels tres és superior a la suma de l'efectivitat dels actius de forma individual. Així mateix, s'han seleccionat antimicrobians no volàtils, sorbat potàssic i benzoat sòdic, els quals son àmpliament empleats a l'industria alimentaria per les seues propietats antifúngiques. Amb els agents actius seleccionats, s'han desenvolupat pel·lícules monocapa de polipropilè (PP) amb diferents concentracions de la mescla activa, citral, hexanal i linalool, a escala laboratori, mitjançant tècniques d'extrusió, i pel·lícules bicapa a escala semi-industrial amb diferents espessors de capa activa mitjançant coextrusió. D'altra banda, s'han desenvolupat safates actives a escala semi-industrial mitjançant termoconformació de làmines obtingudes per coextrusió de compostos de PP i etil vinil acetat (EVA) amb sorbat potàssic o benzoat sòdic com a agents antimicrobians. S'han avaluat les propietats mecàniques, barrera i tèrmiques dels materials actius desenvolupats, així com la seua sellabilidad i transparència. En general, les propietats dels polímers no es van veure afectades de manera rellevant. No obstant això, les safates actives van perdre el seu caràcter transparent a causa de la incorporació dels agents actius no volàtils. S'ha estudiat la cinètica d'alliberament dels compostos actius volàtils i no volàtils a diferents temperatures, determinant els coeficients de difusió dels agents actius mitjançant l'ajust a models matemàtics de difusió basats en la Segona Llei de Fick. Entre els agents volàtils, l' hexanal va mostrar un major coeficient de difusió seguit de citral i linalool. D'altra banda, no va haver-hi a penes diferències en els coeficients de difusió del sorbat potàssic i benzoat sòdic, sent aquests del mateix ordre de magnitud. Igualment, s'han realitzat diferents experiments in vitro a diferents temperatures per determinar les propietats antimicrobianes dels materials desenvolupats. En general, els materials actius presenten una elevada capacitat antimicrobiana que es veu potenciada en augmentar la temperatura d'exposició. Una vegada avaluades les característiques dels materials desenvolupats s'han efectuat assajos d'envasament de taronja i pinya pelada i tallada amb la safata, la pel·lícula activa i la seva combinació (sistema d'envàs actiu). En general, el sistema d'envàs actiu va millorar la conservació de la fruita per un major temps, entre 2 i 7 dies per a la taronja i pinya respectivament, presentant una gran capacitat antimicrobiana i mantenint els paràmetres de qualitat de la fruita en nivells estables per un major temps. Finalment, s'ha estudiat la seguretat d'aquests materials d'acord a la legislació de materials en contacte amb aliments i la legislació alimentària europea, concloent que els materials actius desenvolupats no presenten preocupació per a la seguretat dels consumidors.
Lara Lledó, MI. (2016). Antimicrobial packaging system for minimally processed fruit [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/61388
TESIS
Premiado
Kratz, Cristiane de Pellegrini. "Obtenção de comprimidos contendo grânulos deformantes e grânulos revestidos gastro-resistentes." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2002. http://hdl.handle.net/10183/147657.
Повний текст джерелаMonolythic particulate systems containing the active constituents as coated pellets became great interest due to the improvement of safety and bioavailability. The use of such units as components of tablets shows as main advantages the divisibility of the pharmaceutical dosage form without loosing the desired biopharmaceutical profile of the drug. Consequently for the tablet production, the integrity of the polymeric film must be attained. A strategic option involves the utilization of inert soft pellets, which could be compressed together with the film coated pellets, absorbing the compaction forces. In this work the production of soft pellets was investigated using two wet granulation methods and evaluating the influence of formulation adjuvants on the pellets properties. The extrusion/spheronization technique yielded pellets with acceptable flow, packing and mechanical characteristics. The influence of the adjuvants on the technological steps was carried out through a statistical designed experiment. Microcrystalline cellulose from two producers, the disintegrants sodium croscarmellose and crospovidone, and aqueous and hydroethanolic dispersions of povidone, as binder, were tested. For the tablets development omeprazol gastroresistant film coated pellets were used as model. Aiming at the study of the influence of the soft pellets composition on drug lyoavailability was performed a 23 factorial experiment. The soft pellets protected at different intensities the polymeric coating of the gastroresistant pellets.
Ковбасюк, Роман Васильович, Андрій Андрійович Луциків, Roman Kovbasiuk та Andrii Lutsykiv. "Розробка та дослідження автоматизованої системи керування технологічним процесом виробництва металополімерних труб". Master's thesis, Тернопіль, ТНТУ, 2019. http://elartu.tntu.edu.ua/handle/lib/29734.
Повний текст джерелаР.В. Ковбасюк, А.А. Луциків. Розробка та дослідження автоматизованої системи керування технологічним процесом виробництва металополімерних труб. 151 – автоматизація та комп’ютерно-інтегровані технології. – Тернопільський національний технічний університет імені Івана Пулюя. – Тернопіль, 2019. В магістерській роботі розглянуто процес виготовлення пластикових труб. Було проаналізовано основні аспекти технологічного процесу, визначено найбільш важливі параметри, які суттєво впливають на виробництво труб. Розроблено автоматизовану систему керування процесом екструзії для виробництва полімерних труб. R.V. Kovbasyuk, A.A. Lutsykiv. Development and research of an automated control system for technological process of production of metal-polymer tubes. 151 - Аutomation and computer integrated technologies. - Ivan Puliuyi Ternopil National Technical University. - Ternopil, 2019. In the master's work the process of manufacturing of plastic pipes is considered. The basic aspects of the technological process were analyzed, the most important parameters that significantly influence the production of pipes were identified. An automated control system for extrusion process for the production of polymer tubes has been developed.
ВСТУП 7 1. АНАЛІТИЧНА ЧАСТИНА 8 1.1. Пластмасові труби: область застосування 8 1.2. Переваги і недоліки металопластикових труб 9 1.3. Матеріали для виробництва труб 11 1.4 Наповнювачі, пластифікатори, стабілізатори та інші добавки для виробництва пластмаси 13 2 ТЕХНОЛОГІЧНА ЧАСТИНА 18 2.1. Основні аспекти виробництва полімерних труб 18 2.2. Процес екструзії труб 19 2.3. Процес екструзії загалом 20 2.3.1 Одно шнекове екструдування. 22 2.3.2 Двохвинтові екструзії 26 2.4 Лінія екструзії труб 29 2.4.1 Пластина штифта, оправка та дивавлювана головка. 30 2.4.2 Калібрування та охолодження 32 2.2.3 Знімач і фреза 34 2.2.4 Додаткове обладнання 35 3 КОНСТРУКТОРСЬКА ЧАСТИНА 37 3.1 Загальні аспекти функціонування системи 37 3.2 Цілі системи 38 3.3 Призначення та склад лінії екструзії 38 3.4 Критерій якості створеної системи 40 3.5 Обгрунтування системи контролю 42 3.6 Обгрунтування та створення структурної схеми 43 3.7 Комплекс технічних засобів 47 3.7.1 Обладнання нижнього (польового) рівня 47 3.7.2 Обладнання верхнього (диспетчерського) рівня 50 3.8 Функціональна схема автоматизації 50 3.9 Розробка інформаційних потоків 54 4 НАУКОВО-ДОСЛІДНА ЧАСТИНА 63 4.1. Алгоритм автоматичного регулювання 63 5. СПЕЦІАЛЬНА ЧАСТИНА 70 5.1 Оспис середовища розробки системи СКАДА. 70 6. ОБГРУНТУВАННЯ-ЕКОНОМІЧНОЇ ЕФЕКТИВНОСТІ 77 6.1. Розрахунок норм часу на виконання науково-дослідної роботи 77 6.2 Визначення витрат на оплату праці та відрахувань на соціальні заходи 78 6.3 Розрахунок матеріальних витрат 81 6.4 Розрахунок витрат на електроенергію 82 6.5 Розрахунок суми амортизаційних відрахувань 83 5.6 Обчислення накладних витрат 84 5.7 Складання кошторису витрат та визначення собівартості науково-дослідницької роботи 85 5.8 Розрахунок ціни розробки системи 86 5.9 Визначення економічної ефективності і терміну окупності капітальних вкладень 87 7 ОХОРОНА ПРАЦІ ТА БЕЗПЕКА В НАДЗВИЧАЙНИХ СИТУАЦІЯХ 89 7.1 Організація охорони праці при роботі з системою управління 89 7.2 Електробезпека 91 7.3 Розрахунок заземлення 94 8 ЕКОЛОГІЯ 98 8.1 Екологізація виробництва 98 8.2 Зниження енергоємності та енергозбереження. 99 8.3 Джерела електромагнітних полів, іонізуючого випромінення та методи їх знешкодження. 101 ОСНОВНІ ВИСНОВКИ ДИПЛОМНОЇ РОБОТИ 103 БІБЛІОГРАФІЯ 104
Leite, Ana Mónica Martins de Matos. "Obturação em endodontia." Master's thesis, [s.n.], 2014. http://hdl.handle.net/10284/4378.
Повний текст джерелаIntrodução: A Endodontia constitui uma ciência integrada no conjunto das ciências da saúde. O tratamento endodôntico não cirúrgico divide-se em três grandes fases: Acesso endodôntico, preparação biomecânica e obturação dos canais radiculares. A obturação consiste na etapa final do tratamento endodôntico não cirúrgico oferecendo condições de regeneração aos tecidos perirradiculares. Objetivo: O objetivo deste trabalho é realçar a importância da obturação do sistemas de canais radiculares, apresentar algumas técnicas usadas e avaliar os efeitos nos tecidos periodontais da variação da temperatura e extrusão apical associada às técnicas de obturação termoplásticas. Materiais e Métodos: Para a realização deste trabalho foi efetuada uma pesquisa bibliográfica nas bibliotecas da Universidade Fernando Pessoa e Faculdade de Medicina Dentária da Universidade do Porto e nos motores de busca Pubmed, SciencDirect, SciElO, Google Académico, B-on. As palavras-chaves utilizadas foram: Temperature changes in obturation, temperature damages in obturation, filling gutta-percha extrusion, gutta-percha overfiling, warm obturation, leakage and endodontics, filling and endodontics, System B, Termoplastic. A pesquisa foi limitada a artigos de revisão em Inglês, Espanhol e Português, publicados desde o ano 1999 até ao ano de 2013. Desenvolvimento: As técnicas termoplásticas favorecem a obturação tridimensional dos sistemas de canais radiculares, sendo frequente a obturação de ramificações laterais e deltas apicais. Estas novas técnicas têm a vantagem de proporcionar um melhor selamento apical em que todos os canais radiculares são selados hermeticamente, devido ao material ser facilmente introduzido até as irregularidades do sistema de canais radiculares. Contudo estas técnicas apresentam desvantagens como lesar o ligamento periodontal, cemento e osso alveolar devido à temperatura que é dissipada pela dentina ao sistema de canais radiculares e à elevada extrusão apical. Conclusão: Conclui-se então que o profissional tem que ter a consciência de que cada caso é um caso e como tal necessita de uma avaliação criteriosa de forma a saber que técnica escolher para a obturação dos canais radiculares. Introduction: Endodontics is an integrated science in the field of health sciences. Non-surgical endodontic treatment is divided into three major phases: Endodontic access, biomechanical preparation and obturation of root canals. Obturation is the final stage of non-surgical endodontic treatment and enables regeneration of periradicular tissues. Objective: The objective of this work is highlighting the importance of root canal system obturation, presenting some of the techniques used and evaluating the effects on periodontal tissues of the temperature variation and apical extrusion associated with thermoplastic obturation techniques. Materials and Methods: The study involved a literature review in the libraries of the Fernando Pessoa University and the Dentistry Faculty of the University of Porto and in the Pubmed, SciencDirect, SciElO, Google Scholar and B-on search engines. The key words used for the searches were: Temperature changes in obturation, temperature damages in obturation, filling gutta-percha extrusion, gutta-percha overfilling, warm obturation, leakage and endodontics, filling and endodontics, System B, Thermoplastic. The search was limited to review articles in English, Spanish and Portuguese, published between 1999 and 2013. Development: Thermoplastic techniques favour three-dimensional obturation of root canal systems, and lateral branches and apical deltas are frequently filled. These new techniques have the advantage of providing better apical sealing in which all root canals are hermetically sealed, because the material is easily inserted in the irregularities of the root canal system. However, these techniques have disadvantages, such as damaging the periodontal ligament, cementum and alveolar bone, due to the temperature that is dissipated by the dentine into the root canal system, and due to high apical extrusion. Conclusion: It is concluded that the professional must be aware that each case is different and careful evaluation is therefore required to assess which technique to use to fill root canals.
Costa, Sidonie. "Free Form Extrusion : extrusion of 3D components using complex polymeric systems." Doctoral thesis, 2013. http://hdl.handle.net/1822/24873.
Повний текст джерелаFree Form Extrusion (FFE) is a 3D fabrication process that involves depositing an extruded filament onto successive horizontal planes, in order to build a physic part with a specific geometry. The method is an adaptation of Fused Deposition Modeling (FDM), whereby a commercial pre-extruded ABS filament is replaced by a miniextruder capable of processing a wide range of materials, including homopolymers, polymer blends and nanocomposites. The mechanical performance of FFE parts is controlled by the bonding quality between adjacent filaments both in the horizontal and vertical plans. Adjacent filaments must be sufficiently hot to ensure adhesion, but should then cool down fast enough to avoid excessive deformation due to gravity and weight of the filaments on top. Therefore, it is important to know the evolution in time of the filaments temperature and how it is affected by the major process variables. Although several heat transfer models have been proposed in literature, most assume simplifications without verifying their effective importance. In this work, a detailed analysis of the contributions to the global heat transfer was made using the ABAQUS® software. Heat exchanges with ambient by convection and between adjacent filaments by conduction were found to be the most important. Consequently, these were taken in the energy balance, in order to obtain a rigorous FFE heat transfer analytical model. This analytical solution was then embedded into a routine capable of considering three different deposition patterns, for parts with specific geometries. Moreover, an adhesion criterion was implemented, in order to predict whether the operating conditions and deposition patterns selected for the manufacture of a given part are adequate. The deformation of the filaments was investigated by performing computational experiments with the ABAQUS® software, assuming a temperature dependent viscoelastic response. Since the maximum differences were shown to be quite small (< 0.2%), this phenomenon was considered negligible The consequence of this work is then a computer code that rigorously considers and inter-relates the three phenomena, with the potential of assisting the FFE user in selecting the ideal process parameters in order to obtain a part with good performance. This also allows testing the influence of many process variables and concluding about the most important.
Free Form Extrusion (FFE) é um processo 3D de fabricação que envolve a deposição de um filamento extrudido em planos horizontais sucessivos, por forma a obter uma peça com uma geometria específica. O método é uma adaptação do Fused Deposition Modelling (FDM), através do qual um filamento de ABS comercial pré-extrudido é substituído por uma mini-extrusora com a capacidade de processar uma grande variedade de materiais, incluindo homopolímeros, misturas de polímeros e nanocompósitos. O desempenho mecânico das peças obtidas através da técnica FFE é influenciado pela qualidade de adesão entre filamentos adjacentes, nos planos horizontais bem como verticais. Os filamentos adjacentes devem ser suficientemente quentes para assegurar a adesão, mas ter um arrefecimento suficientemente rápido para evitar a deformação excessiva devido à gravidade e ao peso dos filamentos posicionados nas camadas superiores. Consequentemente, é importante o conhecimento da evolução da temperatura dos filamentos em função do tempo, e como este é afetado pelas principais variáveis do processo. Apesar de vários modelos de transferência de calor terem sido propostos na literatura, na maior parte, simplificações são assumidas sem verificar a sua efetiva importância. Neste trabalho, uma análise detalhada dos intervenientes na transferência de calor foi elaborada usando o software ABAQUS®. Trocas de calor com o ambiente por convecção e entre filamentos adjacentes por condução mostraram ser os mais importantes. Consequentemente, estes foram incluídos no balanço de energia, a fim de obter um modelo analítico rigoroso de transferência de calor para o processo FFE. Esta solução analítica foi então incorporada numa rotina com a capacidade de considerar três tipos diferentes de deposição, para peças com geometrias específicas. Além disso, um critério de adesão foi implementado, a fim de prever se as condições operatórias e os tipos de deposição selecionados para a construção de uma dada peça são adequados A deformação dos filamentos foi investigada através da realização de experiências com o software computacional ABAQUS®, assumindo uma resposta viscoelástica dependente da temperatura. Uma vez que as diferenças máximas mostraram ser muito baixas (< 0.2%), este fenômeno foi considerado negligenciável. A consequência deste trabalho é portanto um código computacional que considera rigorosamente e inter-relaciona os três fenómenos, com a potencialidade de auxiliar o utilizador do processo FFE na seleção ideal dos parâmetros de processo, a fim de obter uma peça com bom desempenho. Também permite testar a influência de diversas variáveis de processo e concluir quais são as mais importantes.
Zhu, Yucun. "Properties of polymeric drug delivery systems prepared by hot-melt extrusion." Thesis, 2002. http://wwwlib.umi.com/cr/utexas/fullcit?p3108547.
Повний текст джерелаLau, Alan Kin Lun, and 劉建麟. "Investigation on Shape-Selectable Gradient Infill Patterns in Extrusion 3D Printing Systems." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/46040270138614704726.
Повний текст джерела國立清華大學
動力機械工程學系
103
The usage of 3D printing has become very popular in recent years due to its usefulness. Depending on the applicable purpose, it has been applied in many sectors; such as military, industrial, automotive, medical, art, food, etc. 3D printing is the process of making three-dimensional objects from a digital source into real physical products. The three most common types of 3D printer are extrusion type, granular type, and light polymerised type. Flexible varieties of material those can be used for 3D printing are ranging from thermoplastics, rubber, silicone, metal, thermoplastic powders to photopolymers. The scope of this thesis covers 3D printing with extrusion type and the results from implementing many different infill pattern strategies. 3D printer with extrusion type creates an object by slicing it into many stacked horizontal layers and uses infill to provide structural integrity by filling the internal section of an object in particular pattern. Proposed results were based upon qualitative research method combining simulation, mechatronic integration, and experimental verification to investigate how the different shapes of pattern and infill densities in the internal structure would affect the strength of the model. The result will offer additional knowledge for design engineer on selecting infill pattern to achieve optimum mechanical properties.
(9741065), Piyush Shrihari Pai Raikar. "EXTRUSION BASED CERAMIC 3D PRINTING - PRINTER DEVELOPMENT, PART CHARACTERIZATION, AND MODEL-BASED SYSTEMS ENGINEERING ANALYSIS." Thesis, 2021.
Знайти повний текст джерелаCeramics have been extensively used in aerospace, automotive, medical, and energy industries due to their unique combination of mechanical, thermal, and chemical properties. The objective of this thesis is to develop an extrusion based ceramic 3D printing process to digitally produce a casting mold. To achieve the objective, an in-house designed ceramic 3D printer was developed by converting a filament based plastic 3D printer. For mold making applications, zircon was selected because it is an ultra-high temperature ceramic with high toughness and good refractory properties. Additionally, alumina, bioglass, and zirconia slurries were formulated and used as the feedstock material for the ceramic 3D printer.
The developed 3D printing system was used to demonstrate successful printing of special feature parts such as thin-walled high aspect ratio structures and biomimetically inspired complex structures. Also, proof of concept with regard to the application of 3D printing for producing zircon molds and casting of metal parts was also successfully demonstrated.
To characterize the printed parts, microhardness test, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses were conducted. The zircon samples showed an increase in hardness value with an initial increase in heat treatment temperature followed by a drop due to the development of porosity in the microstructure, caused by the decomposition of the binder. The peak hardness value for zircon was observed to be 101±10 HV0.2. Similarly, the microhardness values of the other 3D printed ceramic specimens were observed to increase from 37±3 to 112±5 HV0.2 for alumina, 23±5 to 35±1 HV0.2 for bioglass, and 22±5 to 31±3 HV0.2 for zirconia, before and after the heat-treatment process, respectively.
Finally, a system model for the ceramic 3D printing system was developed through the application of the model-based systems engineering (MBSE) approach using the MagicGrid framework. Through the system engineering effort, a logical level solution architecture was modeled, which captured the different system requirements, the system behaviors, and the system functionalities. Also, a traceability matrix for the system from a very abstract logical level to the definition of physical requirements for the subsystems was demonstrated.
Pai, Raikar Piyush Shrihari. "Extrusion Based Ceramic 3D Printing - Printer Development, Part Characterization, and Model-Based Systems Engineering Analysis." Thesis, 2020. http://hdl.handle.net/1805/24752.
Повний текст джерелаCeramics have been extensively used in aerospace, automotive, medical, and energy industries due to their unique combination of mechanical, thermal, and chemical properties. The objective of this thesis is to develop an extrusion based ceramic 3D printing process to digitally produce a casting mold. To achieve the objective, an in-house designed ceramic 3D printer was developed by converting a filament based plastic 3D printer. For mold making applications, zircon was selected because it is an ultra-high temperature ceramic with high toughness and good refractory properties. Additionally, alumina, bioglass, and zirconia slurries were formulated and used as the feedstock material for the ceramic 3D printer. The developed 3D printing system was used to demonstrate successful printing of special feature parts such as thin-walled high aspect ratio structures and biomimetically inspired complex structures. Also, proof of concept with regard to the application of 3D printing for producing zircon molds and casting of metal parts was also successfully demonstrated. To characterize the printed parts, microhardness test, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses were conducted. The zircon samples showed an increase in hardness value with an initial increase in heat treatment temperature followed by a drop due to the development of porosity in the microstructure, caused by the decomposition of the binder. The peak hardness value for zircon was observed to be 101±10 HV0.2. Similarly, the microhardness values of the other 3D printed ceramic specimens were observed to increase from 37±3 to 112±5 HV0.2 for alumina, 23±5 to 35±1 HV0.2 for bioglass, and 22±5 to 31±3 HV0.2 for zirconia, before and after the heat-treatment process, respectively. Finally, a system model for the ceramic 3D printing system was developed through the application of the model-based systems engineering (MBSE) approach using the MagicGrid framework. Through the system engineering effort, a logical level solution architecture was modeled, which captured the different system requirements, the system behaviors, and the system functionalities. Also, a traceability matrix for the system from a very abstract logical level to the definition of physical requirements for the subsystems was demonstrated.
邱世璿. "Analysis and Simulation on Secondary-forming of Multi-port Extrusion Tubes Used in CO2 Air-Condition Systems." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/47982433955949351890.
Повний текст джерела