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1
Gotorbe, Célia. "Contexte métabolique derrière la résistance à la ferroptose des cellules cancéreuses." Electronic Thesis or Diss., Université Côte d'Azur, 2023. http://www.theses.fr/2023COAZ6036.
Abstract:
En 2012, la ferroptose a été défini comme une mort cellulaire régulée dépendante du fer, associée à une augmentation de l'hydroperoxydation des acides gras polyinsaturés (PUFA) de la membrane cellulaire. L'accumulation de lipides hydroperoxydes induit une perte de l'intégrité et de la perméabilité des membranes, conduisant à la mort par explosion. La voie antioxydante impliquant : le transporteur de cystine (xCT), le glutathion (GSH) et la GSH peroxydase 4 (GPX4) a été reconnue comme un axe central anti-ferroptotique de la cellule. Jusqu'à récemment, on pensait que la détoxification des lipides hydroperoxydes était la caractéristique unique de GPX4. Cependant, différentes données soutiennent que la résistance à l'inhibition de GPX4 n'est pas si rare, en particulier dans les cellules cancéreuses hyperplastiques.Ainsi, l'objectif de ma thèse était d'étudier comment le métabolisme énergétique pouvait altérer la sensibilité à l'inhibition de GPX4 dans le cancer. Trois hypothèses ont été étudiés 1) le rôle des voies alternatives pour la détoxification des lipides hydroperoxydes ; 2) le switch métabolique glycolytique diminuant la production interne des ROS ; 3) l'adhésion cellulaire à la matrice extracellulaire (MEC) confère de la résistance aux signaux de stress.Dans un premier temps, j'ai étudié l'importance des voies alternatives impliquées dans la détoxification des lipides hydroperoxydes, tel que la Coenzyme Q10 (CoQ10) et son enzyme de régénération - « ferroptosis suppressor protein 1 » (FSP1). Pour ce faire, nous avons utilisé des lignées cellulaires d'adénocarcinome du côlon, connues pour leur grande résistance à de nombreux agents altérant la cellule. Nos données ont confirmé que la résistance de ces lignées cellulaires était étendue aux agents inducteurs de ferroptose tels que RSL3 (inhibiteur de GPX4) ou iFSP1 (inhibiteur de FSP1). Néanmoins, le phénotype ferroptotique a été induit une fois la combinaison de ces deux agents, suggérant que GPX4 et CoQ10 peuvent être utilisés de manière interchangeable par la cellule. Étonnamment, la délétion génétique de FSP1 combinée à l'inhibition de GPX4 n'a pas induit le même effet, suggérant la possibilité d'une autre adaptation à l'inhibition chronique de FSP1.Par la suite, j'ai alors étudié le contexte cellulaire permettant une adaptation à ces inhibitions au sein des cellules FSP1-KO. Cette étude a montré que les cellules cancéreuses sont capables de survivre à l'inhibition à la fois de GPX4 et de FSP1 par le biais du switch métabolique vers la glycolyse, diminuant ainsi la production interne de ROS. L'utilisant de cellules Warburg-nul à fond génétique FSP1-KO a permis de révéler un phénotype ferroptotique, comparable à celui après inhibition pharmacologique de GPX4 et FSP1.Pour finir, j'ai étudié l'effet protecteur sur la ferroptose de l'attachement cellulaire à la MEC. Pour ce faire, nous avons altéré cette connexion par la délétion de la sous unité 3 de l'intégrine-v3, connue pour son rôle dans la résistance à la radiothérapie des cellules. Nos données montrent clairement que cette délétion impacte les défenses antioxydantes des cellules cancéreuses. En effet, nous avons observé que la signalisation induite par l'intégrine-v3 permettait aux cellules de maintenir une forte expression de GPX4, très probablement en affectant directement le centre cellulaire général du capteur de nutriments et de la synthèse protéique, « mammalian target of rapamycin complex 1 » (mTORC1). Par conséquent, les cellules 3-KO ont montré une sensibilité plus élevée à la ferroptose induite par radiations.Collectivement, les résultats obtenus au cours de ma thèse indiquent que deux voies anti-ferroptotique indépendantes (GPX4-GSH et CoQ10-FSP1) sont interchangeables ainsi que dans le contexte métabolique plus large de la cellule cancéreuse. Ainsi, l'induction de la ferroptose pour le traitement du cancer devrait être couplée à des modulateurs métaboliquesIn 2012, ferroptosis had been contextualized as a novel, iron-dependent regulated type of cell death associated with increase of hydroperoxidation of polyunsaturated fatty acids (PUFAs) of the cell membrane. The accumulation of lipids hydroperoxides disrupts the plasma membrane integrity and selective permeability, leading to cell bubbling and death by explosion. During the past decade, antioxidant pathway involving: the cystine transporter (xCT), glutathione (GSH) and GSH peroxidase 4 (GPX4) had been recognized as a central anti-ferroptotic axis of the cell. Until recently, it has been believed that detoxification of lipid hydroperoxides is the unique feature of GPX4; however, accumulating amount of data argues that it might not be the case. Namely, studies showed that resistance to GPX4 inhibition is not so rare, especially in the hyperplastic cancer cells.Thus, the main goal of my thesis was to investigate how energetic metabolism could alter sensitivity to GPX4 inhibition in different cancer types. Three major hypotheses have been investigated: 1) alternative pathway for lipid hydroperoxides detoxification; 2) switch from oxidative to glycolytic phenotype (decrease of internal ROS production); 3) cell adhesion to extracellular matrix (ECM) conferring resistance to many stress signals.In the first part of my thesis, I investigated the importance of the alternative pathway involved in detoxification of the lipid hydroperoxides, comprised of Coenzyme Q10 (CoQ10) and its regenerating enzyme - ferroptosis suppressor protein 1 (FSP1). To investigate this issue, we used colon adenocarcinoma cell lines, notoriously known as highly resistance to many different cell-damaging agents. Data presented here confirmed that the resistance of this cell lines was extended to ferroptosis-inducing agents such as RSL3 (GPX4 inhibitor) or iFSP1 (FSP1 inhibitor). Nonetheless, the ferroptotic phenotype was revealed once the combination of the agents targeting both GPX4 and FSP1 was applied. This clearly suggested that GPX4 and CoQ10 can be used by the cell interchangeably. Surprisingly, FSP1 genetic deletion combined with GPX4 inhibition did not induce the same effect suggesting another possible adaptation to chronic inhibition of FSP1.Thus, in the second part of my thesis I investigated cellular context that permit adaptation of the cancer cell to the inhibition of both anti-ferroptotic pathways by using FSP1-KO cells. The consequent work showed that the cancer cells can survive dual inhibition of GPX4 and FSP1 by switching their metabolism toward glycolysis and thereby decreasing the internal production of ROS. By using glycolysis-null FSP1-KO cells we succeeded to reveal the ferroptotic phenotype, comparable with the one observed upon pharmacological inhibition of FSP1 and GPX4.Finally, the third part of my thesis interrogated the protective effect that cell-to-matrix attachment has on the ferroptosis induction. To investigate this issue, we compromised this connection through the deletion of b3 subunit of the integrin-avb3, known to be important for cell resistance to radiotherapy and relapse. Our data clearly showed that this intervention significantly compromised antioxidant defense of the cancer cell. More precisely, we showed that signaling stemming from avb3 cells, allows cells to maintain high expression of GPX4, most likely by directly affecting the general cellular hub of nutrient sensor and protein synthesis, mechanistic target of rapamycin complex 1 (mTORC1). Consequently, b3-KO cells showed significantly higher sensitivity to ferroptosis induced by radiation.Collectively, data obtained during my PhD thesis indicate that in the case of cancer cells, two independent anti-ferroptotic pathways (GPX4-GSH and CoQ10-FSP1) operate within the overall physiological context and in some instances, their inhibition have to be coupled with other metabolic modulators, such as inhibitors of glycolysis or cell-to-matrix attachment
2
Rolland-Turner, Magali. "Développement d'un vaccin immunocontraceptif : mise au point de tests immunologiques dans le modèle vulpin et développement de vaccins ADN avec les antigènes spermatiques fSP13 et fSP8." Nancy 1, 2005. http://www.theses.fr/2005NAN11303.
Abstract:
Le but de ce travail était tout d'abord, la mise au point d'outils immunologiques permettant l'analyse de la réponse immune humorale et cellulaire chez le renard (Vulpes vulpes). Après avoir sélectionné des anticorps reconnaissant les différentes classes d'immunoglobuline de renard, le modèle antigénique ovalbumine et choléra toxine B a été utilisé pour mettre au point les techniques ELISA et ELISPOT. Quatre cytokines vulpines Il2, Il6, Il10 et INFy ont été clonées et séquencées, et une technique d'analyse de leur expression par RT-PCR quantitative, après re-stimulation antigénique in vitro de PBMCs vulpins a été mise au point. Par la suite, différents vaccins ADN utilisant le vecteur vaccinaI commercial pVAX1 et les antigènes spermatiques spécifiques du testicule fSP13 et fSP8 identifiés au laboratoire ont été construits. La fonctionnalité de celles-ci à tout d'abord été testée in vitro pour l'expression de fSP 13 et fSP8 après transfection de cellules MDCK.
3
Gonçalves, Joel. "Soldagem pontual por fricção (FSpW) de poliamida 6." Universidade Federal de São Carlos, 2015. https://repositorio.ufscar.br/handle/ufscar/7314.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Friction Spot Welding (FSpW) is an innovative technique developed and patented in 2005 by the Helmholtz Zentrum Geesthacht (HZG) research center in Germany. FSpW uses the friction between a rotating tool and the workpieces to generate heat enough to cause diffusion across the interface to consolidate the weld. This new welding technology has been tested and optimized with the objective of produce overlap weld joints between two polyamide 6 plates. Full factorial design of experiments (24) and analysis of variance (ANOVA) allowed to explain the effects of weld parameters as rotational speed (RS), welding time (WT), plunge depth (PP), holding pressure time (HPT) and the interactions between these main parameters on the microstructural characteristics and mechanical strength of the joints. The rotational speed (RS) and welding time (WT), within the limits studied, had greater influence on the mechanical single lap shear strength of the joints that achieved up to 26 MPa. This behavior was related to the higher heat generation during the weld, reaching temperatures of up to 275°C, thereby increasing the welded area. The parameter holding pressure time (HPT), designed in this study allowed the cooling and solidification of the polymer under pressure, improving the weld surface finishing and avoiding defects as voids in the weld area. The most common failure for the joints with higher mechanical strength was the fracture of one of the plates while the joints with lower mechanical strength showed interface shear failure. The degree of crystallinity of PA6 in the welded area did not show a significant difference as compared to the base material. The molecular weight of PA6 in the welded area was reduced in the worst case 7% as compared to the base material (Mv = 41.800 g/mol), and that reduction occurred linearly with the increase of the temperature during the welding; however, that low degree of degradation was not found to affect the mechanical strength of the joints. These characteristics emphasize the potential of this FSpW as an alternative to the current welding methods for polyamide 6.
A Soldagem Pontual por Fricção (FSpW) foi desenvolvida e patenteada pela Helmholtz-Zentrum Geesthacht (HZG), na Alemanha. A FSpW é uma técnica de soldagem pontual que ocorre por meio da fricção de uma ferramenta, com movimentos rotacional e axial, através das amostras, gerando aquecimento suficiente para fundir e misturar localmente o(s) polímero(s), com posterior consolidação sob pressão. Este estudo teve como principal objetivo investigar o uso da FSpW na fabricação de juntas pontuais entre chapas de poliamida 6 (PA6) sobrepostas. Experimentos do tipo fatorial completo (24) e análise de variância (ANOVA) possibilitaram a compreensão dos efeitos dos parâmetros de soldagem, velocidade de rotação (VR), tempo de soldagem (TS), profundidade de penetração da ferramenta (PP), tempo de consolidação (TC), e de suas interações, sobre características microestruturais e a resistência mecânica das juntas. Os parâmetros velocidade de rotação (VR) e tempo de soldagem (TS), dentro dos limites estudados, apresentaram maior influência sobre a resistência mecânica das juntas, alcançando 26 MPa. Este comportamento foi relacionado à maior geração de calor durante a soldagem, atingindo temperaturas de até 275oC, consequentemente, aumentando a área soldada. A utilização do parâmetro tempo de consolidação (TC), idealizado neste estudo, possibilitou o resfriamento e solidificação do polímero sob pressão, melhorando o acabamento superficial da solda e evitando a formação de defeitos. Juntas com maiores valores de resistência ao cisalhamento sob tração apresentaram maior probabilidade de falha por fratura de uma das chapas, enquanto que juntas menos resistentes falharam por separação das chapas. O grau de cristalinidade da PA6 nas soldas não sofreu variação significativa e observou-se um decréscimo de até 7% na massa molar da PA6 em relação ao material de base (Mv = 41.800 g/mol) que ocorreu de forma linear com o aumento da temperatura durante a solda, porém essa alteração não comprometeu a resistência mecânica da solda.
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Rotevatn, Njål. "Design and testing of Flux Switched Permanent Magnet (FSPM) Machines." Thesis, Norwegian University of Science and Technology, Department of Electrical Power Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9054.
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This thesis offers a short overview of the most important stator mounted permanent magnet machines, with a closer look on the FSPM design. A FSPM machine have been built and tested as a generator, to get a better understanding of the machine concept. The focus of the work have been on the well documented 12/10 (Stator teeth/ Rotor teeth) design while the novel 12/14 pole design have also been tested, as a rotor change is the only difference between the two designs. The machine have been simulated in COMSOL, where inductances, back emf and cogging have been found and compared with the measured results.
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Kaur, Rajween. "Regulation of ATGL-mediated lipolysis by FSP2/CIDEC in human adipocytes." Thesis, Boston University, 2013. https://hdl.handle.net/2144/21186.
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Thesis (M.A.) -- Boston University, 2013.Increased free fatty acid (FFA) flux from adipocytes due to increased lipolysis, has a key contribution in the pathophysiology of metabolic disease. There is a lack of knowledge of the molecular components which determine the TG storing capacity and lipolysis in adipocytes. Studies from our lab and others have demonstrated the role of a lipid droplet associated protein, Fat Specific Protein 27 (FSP27, also called CIDEC), in regulating triglyceride accumulation and lipolysis in adipocytes, but its mechanism of action remains elusive. In the present study, we used cultured human primary adipocytes to define the role of FSP27 in regulating both basal and isoproterenol-stimulated lipolysis. Using a combination of RNAi and adenoviral mediated overexpression techniques, we have shown that FSP27 regulates ATGL-mediated lipolysis by down-regulating gene and protein expression of ATGL. Furthermore, our data shows that FSP27-mediated triglyceride accumulation is suppressed in the absence of ATGL. Our results support a model whereby FSP27 regulates ATGL-mediated lipolysis to accumulate triglycerides in human adipocytes
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Bairam, Emna. "Etude des processus écophysiologiques caractérisant la distribution du carbone entre les sources et les puits au sein de la charpentière du pommier. Eléments pour un modèle fonction-structure." Thesis, Rennes, Agrocampus Ouest, 2017. http://www.theses.fr/2017NSARC129/document.
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La synthèse et le transport du carbone chez le pommier repose sur un ensemble de mécanismes complexes et imbriqués dépendants de facteurs endogènes et exogènes. Uneapproche combinant une caractérisation écophysiologique et l’utilisation d’un modèle structure-fonction de la plante (Functional-Structural Plant Model, FSPM) présente un moyenintéressant pour ce champ de recherche dans la mesure où un modèle structure-fonction permet d’intégrer la topologie et la géométrie de la plante et de ses différents organes à l’ensemble des facteurs impliqués dans l’assimilation et le transport du carbone et de l’eau. Le travail présenté ici a contribué à la compréhension des relations sources-puits mais égalementà l’élaboration d’un modèle FSPM à plusieurs niveaux. Premièrement, le développement de modèles de prédiction de l’architecture des différentes pousses du pommier à partir de variables simples apporte un moyen novateur pour simplifier la simulation de l’architecturedes branches mais égalementpour quantifi er de façon robuste la surface foliaire. Deuxièmement,l’établissement d’un réseau de corrélations entrevariables morphométriques des différents organes issus dubourgeon mixte met en évidence les organes les plus connectésà l’échelle du spur. Enfi n, une étude des relations sourcespuitsà l’échelle de la branche a permis, d’une part, une caractérisationde la régulation de la photosynthèse nette desfeuilles en réponse à des changements dans le ratio sources/puits mais aussi en fonction des types de feuilles et, d’autrepart, à mettre la lumière sur l’inflThe synthesis and the transport of carbon in apple are basedon a whole host of complex and interlaced mechanisms thatdepend on endogenous and exogenous factors. An approachthat combines the ecophysiological characterisation with theuse of a Functional-Structural Plant Model (FSPM) representsan interesting method in this fi eld of research, inasmuch assuch an FSPM allows integrating the topology and the geometryof the plant and its constituting organs with the entiretyof factors involved in assimilation as well as water andcarbon transport. The present study has contributed to thebetter understanding of the source-sink relations characterizingthis system but also to the elaboration of a multi-scaledFSPM. First, the development of models for the prediction ofthe architecture of different shoot types in apple from simplevariables provides a novel way to simplify the simulationof theinitial structure of branches but also to quantify leaf area in arobust manner. Second, the creation of a network of correlationsamong morphometric variables of the different organsformed by the mixed bud of apple clearly shows the functionalrelations among the spur organs. In the end, the study ofsource-sink relations at the branch scale has allowed, on theone hand, to characterize the regulation of net photosynthesisas a function of a changed source/sink ratio but also asa function of leaf type and, on the other hand, to shed somelight on the infl uence that the competition among fruits hason increasing sink strength and thus regulating the leaf
7
Bland, Marc Thompson. "Investigation of superplastic behavior in FSP 5083 aluminum alloy." Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion-image.exe/07Jun%5FBland.pdf.
Abstract:
Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, June 2007.Thesis Advisor(s): McNelley, Terry R. ; Su, Jianqing. "June 2007." Description based on title screen as viewed on November 7, 2007. Includes bibliographical references (p. 47-48). Also available in print.
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Szabó, Hugo. "Elektrický stroj s přepínáním magnetického toku." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-443090.
Abstract:
The goal of this thesis is to create a literature search about a rotating electrical machine with switching of magnetic flux, to explain its construction concept and its operating behavior, to create an initial concept of generator, calculate chosen construction with finite element method analysis and to compare analysis results with analytical design. To create a concept of the generator one of available designing procedures will be used.
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Chideya, Zorodzai. "Theory-driven evaluation of a Financial Services Provider's (FSP) induction programme." Master's thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/10267.
Abstract:
Includes bibliographical references (leaves 40-46).Many contemporary organisations implement programmes to gain a competitive advantage over their rivals. Such organisations invest money and human capital into such programmes and this has given rise to the need for accountability of these programmes. The field of programme evaluation makes use of social science research methods to investigate the effectiveness of programmes and to offer guidance on how best to improve these programmes. Programme evaluation has different approaches and theory-driven evaluation is one such approach. This dissertation makes use of the theory-driven evaluation approach to develop a programme theory for a Financial Services Provider (FSP)'s induction programme. The induction programme that is implemented by the FSP is targeted at new employees and aims to improve their knowledge and skill and in the long term to retain these new employees.
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Burke, Michael J. Lykins Richard C. "Fire Support Planning System (FSPS) : a commercial off the shelf (COTS), windows-based, wireless approach /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1999. http://handle.dtic.mil/100.2/ADA370852.
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Thesis (M.S. Information Technology Management) Naval Postgraduate School, September 1999."September 1999". Thesis advisor(s): Terrance C. Brady, Rudolplf P. Darken. Includes bibliographical references (p. 97-99). Also available online.
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Burke, Michael J., and Richard C. Lykins. "Fire Support Planning System (FSPS) : a commercial off the shelf (COTS), windows-based, wireless approach." Thesis, Monterey, California. Naval Postgraduate School, 1999. http://hdl.handle.net/10945/26548.
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Given the rapid rate of today's technological changes and in an environment of austere budgets, DoD faces a significant challenge relating to hardware and software. This joint thesis explores two major issues. First, whether commercial off the shelf (COTS) software development tools in conjunction with the Rapid Application Development (RAD) software development methodology can be used to deliver meaningful applications for the warfighter. Second, this thesis describes an overview of the commercial wireless technologies available today and whether these technologies could enhance the capabilities of the Marine Corps tactical communications architecture to transmit RAD/Win32 compliant software applications. As a specific demonstration case, the authors developed the Fire Support Planning System (FSPS) software which would ride on top of the Marine Corps' Command and Control Personal Computer (C2PC) application
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Rosendo, Tonilson de Souza. "Estudo do desempenho mecânico de solda(s) ponto por fricção (FSpW) da liga AA6181-T4." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/18981.
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Uma nova tecnologia de soldagem, denominada Friction Spot Welding (FSpW) utiliza uma ferramenta rotativa especial que transfere energia térmica e mecânica ao material sendo soldado. O processo se destina à soldagem de juntas sobrepostas, primariamente para ligas leves, mas, em teoria, é aplicável a qualquer material que apresente boa plasticidade. A crescente competitividade tem motivado as indústrias à otimização de processos, o que tem levado ao uso cada vez mais expressivo de ligas leves nas indústrias automobilística e aeronáutica. Soma-se a isto a necessidade de redução do consumo de combustível em veículos, dada a crescente preocupação com as questões do meio ambiente. Estes fatores tornam o processo FSpW um grande atrativo seja na substituição ou no uso complementar de tecnologias consagradas como soldagem a ponto por resistência elétrica e a LASER (indústria automobilística) e rebitagem (indústria aeronáutica). Neste trabalho foi feito um estudo da aplicabilidade do processo FSpW para a liga de alumínio 6181-T4 que tem forte apelo na indústria automotiva. O estudo teve como objetivo avaliar os efeitos dos parâmetros de processo, na microestrutura, na geometria da junta e no desempenho mecânico, além de buscar a otimização do processo para a liga em estudo. Tal otimização foi feita por meio do estudo dos mecanismos de fratura das soldas sob solicitação monotônica de cisalhamento e de tração. Juntas sobrepostas foram produzidas utilizando condições de soldagem variadas, por meio de diferentes combinações de velocidade de rotação e tempo de processamento. Os resultados obtidos mostraram que soldas de alta resistência e de reprodutibilidade são possíveis com este novo processo. O botão de solda FSpW da liga 6181-T4 é constituído de três elementos (União Principal, União Secundária e Cunha). As características destes elementos, somada às transformações metalúrgicas decorrentes do processo, afetam fortemente o comportamento em fratura das juntas e, conseqüentemente, o seu desempenho mecânico.A new welding technique referred to as Friction Spot Welding (FSpW) suitable to produce overlap joints uses a spindle to transfer mechanical and thermal energy to the material being welded. Although initially developed for lightweight alloys this welding technique is suitable to virtually any material presenting some degree of plasticity. The process has shown potential applicability to complementary use together with other well established techniques such as resistance and LASER spot welding and riveting. In this work a study of the application of the FSpW process for the automotive aluminium alloy 6181-T4 was performed. Overlap joints were produced with different welding conditions by using different combinations of tool rotation speed and welding time. The objectives were the assessment of the welding parameters on the strength, microstructure and geometry of the joints, as well as the optimization of the process. The welded joints were assessed mechanically and metallurgically aiming the investigation of the mechanisms of joint formation and the optimization of the welding parameters. The methodology used for the optimization of the welding parameters was the fracture mechanisms of the joints under shear and tension loads. The results revealed that sound welds with high strength and toughness are possible to be produced with the 6181-T4 alloy using this process. Moreover, the metallurgical investigation revealed that the spot joint is comprised by three elements: Primary Union, Secondary Union and Rim. It was found that the characteristics of these three elements in addition to the metallurgical transformations imposed to the material play a fundamental role on the fracture behaviour of the joints and thus, on its mechanical behaviour.
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Sun, Ning. "Friction stir processing of aluminum alloys." Worcester, Mass. : Worcester Polytechnic Institute, 2009. http://www.wpi.edu/Pubs/ETD/Available/etd-050109-144331/.
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Inturi, Siva Nagi Reddy. "Nano-Catalyst Synthesized by Flame Spray Pyrolysis (FSP) for Visible Light Photocatalysis." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1511884949728835.
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Gao, Ao. "Evolution of antagonistic relationships in proteins: a case study of RADIALIS- and DIVIRICATA-like genes." VCU Scholars Compass, 2017. http://scholarscompass.vcu.edu/etd/5034.
Abstract:
The antagonistic relationship of proteins describes the opponent interactions that result in one protein suppressing the function of another. Developmental genetic studies of Antirrhinum majus demonstrated that two transcription factors from the MYB gene family, RAD and DIV, interact through antagonism to regulate floral dorsoventral asymmetry. Interestingly, similar antagonistic interactions were found among proteins of FSM1 (RAD-like), MYBI (DIV-like), and DRIF in Solanum lycopersicum, which is involved in fruit development. Here, we report on the homology of these antagonistic MYB proteins based on reconstruction of the phylogeny of I-box-like and R-R-type clades, where RAD- and DIV-like belong, respectively. Three paralogs of RAD-/I-box-like genes, RAD1, RAD2, and RAD3 are reprensent in the phylogeny, which originated in the common ancestor of the core eudicots. In contrast, R-R-type sequences fall into two major clades, RR1 and RR2, which are the result of gene duplication in the common ancestor of monocots and dicots. RR1 was divided into clades, RR1A, RR1B, and RR1C, while RR2 divided into clades, RR2A/DIV1, RR2B/DIV2, and RR2C/DIV3. We demonstrate that among similar antagonistic interactions in A. majus and So. lycopersicum, RAD-like genes originate from the RAD2 clade, while DIV-like genes originate from distantly related paralogs of the R-R-type lineage.
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Bates, William. "Casting repair and Surface Modification of Aluminum Alloys using Friction Stir Processing (FSP)." Thesis, Högskolan Väst, Avdelningen för Industriell ekonomi, Elektro- och Maskinteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-16675.
Abstract:
This thesis investigates using friction stir welding to repair common surface defects found in aluminum-silicon sand castings. Wherein, the effect of welding parameters: weld RPM, weld speed, and number of weld passes, were evaluated using hardness, porosity density, welding temperature, microstructure refinement as metrics. Therefrom, the results strongly suggest friction stir welding: reduces porosity size, reduces porosity density in a specific area, increases average hardness, improves hardness uniformity, increases surface roughness, redistributes microstructure features in a manner that theoretically improves strength, and maintains a welding temperature less than 660 degrees Celsius.
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Mjali, Kadephi Vuyolwethu. "Analysing the effect of FSP on MIG-laser hybrid welded 6082-T6 AA joints." Thesis, Nelson Mandela Metropolitan University, 2007. http://hdl.handle.net/10948/563.
Abstract:
Friction Stir Processing (FSP) of aluminium alloys has been used to modify and improve the microstructure and relevant properties of fusion welded aluminium alloys. The effect of FSP on MIG-Laser Hybrid (MLH) welded aluminium alloy 6082-T6 mechanical and microstructural properties has been studied in this research. The FSP process was used on 6mm thick aluminium alloy plates and a tool was designed specifically for FSP, and the effect of varying speeds was analysed before the final FSP welds were made. The effect of FSP was analysed by optical microscopy, tensile, microhardness and fatigue testing. The aim of the study was to determine whether the FSP process has a beneficial influence on the mechanical properties and metallurgical integrity of MIG-Laser Hybrid welded 6082-T6 aluminium alloy with varying gap tolerances. Three welding processes were compared, namely combined Friction Stir Processing on MIG-Laser hybrid process (FSP-MLH), MLH and Friction Stir Welding (FSW) as part of the analysis. (FSP was carried out on MLH components when it was found that FSP is not an entirely complete welding process but rather a finishing process per se.) The aim of this dissertation is to investigate the effects of the FSP process on the weld quality of MLH welded joints and also to compare this to individual processes like FSW and MLH. This investigation was undertaken in order to gain an understanding of the effect of these processes on fatigue performance and microhardness distribution on aluminium alloy 6082-T6 weld joints.
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Morabe, Stephanie Jean. "Factors associated with Milestones of Recovery Scale (MORS) scores of adults receiving FSP services." Thesis, California State University, Long Beach, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1585812.
Abstract:
The purpose of this study was to see if factors such as age, gender, and diagnoses have an effect on one's ability to recover from the symptoms of his or her mental illness. Data was collected from one of five FSP teams at MHA Village. Within the team selected, members with all necessary data were included. The research analyzed the responses of 55 MHA Village members.
The results of this study show that MORS scores do not differ by gender, Axis I diagnosis, having an Axis II diagnosis, income source, race, primary pay source, referral source, age, length of enrollment, or family income. There was, however, a positive correlation between family income and length of enrollment. Future research is needed to gain an in-depth understanding and knowledge of the diverse factors associated with mental health recovery, as well as how to more accurately measure mental health recovery in the first place.
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Torabmostaedi, Hosein. "Computer simulation of processing controls on the formation and growth of nanoparticles in FSP." Thesis, Kingston University, 2014. http://eprints.kingston.ac.uk/28222/.
Abstract:
In this study, the effect of nozzle geometries and processing controls during Flame Spray Pyrolysis (FSP) process were investigated theoretically on a pilot-scale reactor (production rates up to 5 kg h-1 zirconia) and lab scale reactor (production rates up to 74 g h-1 titania). The focus was on the controlled synthesis and continuous production of nanoparticles at high production rates as well as the study of particle formation and growth inside spray flames. The computational models developed in this study were validated by the measured data available from literature for particle dynamics in spray flames and used to process optimization and reactor design. Chapter one presents an overview of applications of nanoparticles and recent advances in synthesis of nanoparticles by Vapour-fed Flame Synthesis (VFS) and Flame Spray Pyrolysis (FSP). A general introduction on the formation and growth of nanoparticles in the gas-phase synthesis of nanoparticles is presented with emphasis on the mechanisms that control the particle morphology after the initial formation of the monomers. Finally, some existing models in the field are presented and compared. The mathematical models adopted in this study are fully described in chapter two. Several numerical models were developed to predict dynamic viscosity and surface tension of precursor solutions, the pumping pressure of precursor solution, the sauter mean diameter (SMD) of droplets during atomization and the particle growth inside the flame by coagulation and sintering. These models were coupled with the computational fluid dynamic (CFD) code to simulate FSP process. The models were validated by comparison with experimental data developed in this study and literatures. In chapter four, the effect of reactor geometries and processing parameters on the temperature and velocity profiles, droplet evaporation and particle growth were predicted using the validated computational models. The results show that the oxidant/dispersion gas gap size and the oxygen content of oxidant/dispersion gas have a big impact on the flame structure and ultimately the particle growth in the flame. In chapter five, investigation is performed to examine the effect of process parameters on the growth of zirconia particles at low, medium and high precursor concentrations. The results show that fine nanoparticles could be synthesized at low precursor concentration and medium production rates while further studies are needed at higher precursor concentrations and production rates. Therefore, in the sixth chapter, emphasis is placed on industrial production of nanoparticles at higher precursor concentrations. A process operation window for industrial-scale production of zirconia nanoparticles using medium and high precursor concentration was developed. The possible solutions to optimize pump performance and atomization quality at industrial scale production rates using high precursor concentration in FSP were investigated. The quantitative results given in this section can be used as a design guide for a prototype industrial FSP nanoparticle production line. Chapter seven extends the work above and investigates the possibility of quenching the FSP flames at industrial scale production rate by using different reactor configurations. The simulations show how choosing the right configuration and process parameters can affect the characteristics and collection of particles at above the burner. In chapter eight, the applicability of the developed approach for particle simulation of zirconia in the previous chapters is examined for flame spray synthesis of titania. In addition, a series of parametric studies was performed to assist better understanding and control over FSP synthesis of Ti02 nanoparticles. In the ninth chapter, a short summary is given along with recommendations for future investigations.
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Gygi, Cameron Scott. "Crack Healing in 304L Stainless Steel Using Additive Manufacturing and Friction Stir Processing (FSP)." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6530.
Abstract:
Continuing an investigation on using FSP to heal stress corrosion cracks (SCC) in welds on nuclear reactors, this study seeks to use AM in addition to FSP to aid crack repair. Previous studies address that current repair technology on nuclear reactors involves the use of TIG welding which can allow helium atoms to aggregate and form voids at the grain boundaries. This weakens the material and renders the repair ineffective. Another previous study evaluated the effectiveness of FSP alone in repairing SCC which did have defects depending on the parameters used during FSP. This study evaluated the use of AM in addition to FSP. Literature is available on FSP and AM separately and literature is available on technologies that used both them together. However, the current processes that are available that use both AM and FSP can be expensive and may be impractical for some purposes. This study shows a new process that is both less expensive and more practical in SCC repair. Initial proof of concept trials was performed on 1018 mild steel using both wire fed additive and insert additive technologies. A slot would be removed and filled in with an additive process and processed using FSP. Because of poor repeatability, substantial distortion, and voids present this study went forward using insert technologies in further experiments rather than wire wed additive technologies. In addition, the depth and width of the insert or area where the added material would be placed was varied in initial trails. Tensile testing was performed on initial steel trials and the stainless steel experiments and it demonstrated a correlation between depth of the added material and the tensile strength. Micro-hardness mapping performed on initial steel trials also showed hardening in the FSP stir zone. Three-point bend tests were performed to show that an existing crack underneath the FSP zone would not propagate through the nugget. All evaluations supported a substantial increase in yield strength increased after FSP.
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Dai, Chen. "Development of Aluminum Dross-based Material for Engineering Application." Digital WPI, 2012. https://digitalcommons.wpi.edu/etd-theses/16.
Abstract:
Aluminum dross is a by-product of Aluminum production. At present, dross is processed in rotary kilns to recover the Al, and the resultant salt cake is sent to landfills; although it is sealed to prevent from leaching, the potential for leaching exists and could harm the environment as the salt cake contains fluorides and other salts. Furthermore, much energy is consumed to recover the Al from the dross; this is energy that can be saved if the dross could be diverted and utilized as an engineering material. The objective of this work is to eliminate waste and instead utilize the waste in a natural cycle (closed loop) by using it as an engineered material. Three avenues were investigated to utilize the dross: (i) refractory materials; (ii) aluminum composites; (iii) high temperature additive for de-sulphurizing steel. We have found that the use of dross waste to manufacture refractory material has much merit. Mechanical property evaluations revealed the possibility for dross waste to be utilized as filler in concrete, resulting in a 40% higher flexural strength and a 15% higher compressive strength compared to pure cement. These results will be presented and discussed.
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Zhou, Wei. "High resolution microscopy of NdFeB magnets produced from flash spark plasma sintering (FSPS) and the hydrogen ductilisation process (HyDP)." Thesis, University of Birmingham, 2019. http://etheses.bham.ac.uk//id/eprint/8710/.
Abstract:
In recent years, the increasing demand for rare earth magnets for use in motors and machines has led to the need for more efficient use of NdFeB materials. Novel processing techniques have been developed to produce NdFeB materials with excellent magnetic properties without the need for heavy rare earth elements. Two specific novel processes including the Flash Spark Plasma Sintering (FSPS) process and the Hydrogen Ductilisation Process (HyDP) were studied in this project with the focus on the use of microstructural analysis and magnetic measurements to fully understand the mechanisms, hence develop and optimise the processing conditions for production of fully dense anisotropic magnets. The most optimal FSPS sample demonstrates a uniform, fine-grained structure with a high degree of crystallographic alignment, leading to a high coercivity (1438 kA m\(^−\)\(^1\)) and remanence (1.16 T) giving a BH\(_m\)\(_a\)\(_x\) of 230 kJ m\(^−\)\(^3\). While with appropriate s-HDDR and compression conditions, the HyDPed sample exhibits a typical s-HDDR microstructure with a submicron grain size. It is shown in the work that the disproportionated sample shows an enhanced ductility and thus can be shaped at room temperature, and a useful degree of anisotropy is produced within the HyDPed sample during the compression.
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Velard, Corentin. "Influence de paramètres microstructuraux sur les propriétés de corrosion d'un alliage de magnésium biorésorbable hyperdéformé." Thesis, Université Grenoble Alpes, 2021. http://www.theses.fr/2021GRALI037.
Abstract:
Les alliages de magnésium sont des candidats prometteurs pour des applications d’implants biorésorbables. Dans ce contexte, la compréhension du lien entre microstructure et mécanismes de corrosion et de dégradation des alliages de magnésium constitue un enjeu important. L’objectif de ce travail a été d’étudier l’influence de la microstructure sur la dégradation d’un alliage Mg-2%Ca biocompatible. Pour cela, deux procédés d’hyper-déformation (le Friction Stir Processing et dans une moindre mesure l’Equal Channel Angular Pressing) ont été utilisés afin de modifier les paramètres microstructuraux. Ces deux procédés se sont avérés particulièrement efficaces pour réduire la taille des grains (des tailles de l’ordre du micron ont ainsi pu être produites), modifier la répartition spatiale et la taille des secondes phases présentes dans l’alliage et développer des textures cristallographiques particulières. Au final, malgré ces variations microstructurales importantes, l’impact sur la vitesse de dégradation demeure assez limité. L’analyse du comportement électrochimique a aidé à décorréler l’influence de ces paramètres microstructuraux sur la vitesse de dégradation ; certains d’entre eux pouvant se compenser. Si l'affinement des grains semble améliorer la résistance à la corrosion, en raison d’un film de produits de corrosion probablement plus cohérent avec le métal, le rôle joué par les secondes phases apparaît plus complexe : la simple dispersion spatiale des particules de seconde phase affecte peu le comportement électrochimique alors que l'affinement de ces particules semble influencer notablement la couche de produits de corrosion. Enfin, comme attendu, la texture cristallographique joue également un rôle significatif dans la résistance à la corrosion. Ce travail a ainsi permis de contribuer à une amélioration des connaissances concernant l’influence de la microstructure sur le comportement électrochimique d'un alliage magnésium-calciumMagnesium alloys are promising candidates for bioresorbable implant applications. In this context, understanding the link between microstructure and corrosion/degradation mechanisms of magnesium alloys is an important issue. The objective of this work was to study the influence of the microstructure on the degradation of a biocompatible Mg-2%Ca alloy. For this purpose, two hyper-deformation processes (Friction Stir Processing and to a lesser extent Equal Channel Angular Pressing) were used to modify the microstructural parameters. These two processes proved to be particularly effective in reducing the grain size (micron-sized grains could be produced), modifying the spatial distribution and size of the second phases present in the alloy and developing specific crystallographic textures. Finally, despite these important microstructural variations, the impact on the degradation rate remains quite limited. The analysis of the electrochemical behaviour helped to decorrelate the influence of these microstructural parameters on the degradation rate; some of them compensating each other. If grain refinement seems to improve the corrosion resistance, due to a coverage of corrosion products probably more coherent with the metal, the role of the second phases appears more complex: the spatial dispersion of the second phase particles has little effect on the electrochemical behaviour whereas the refinement of these particles seems to significantly influence the layer of corrosion products. Finally, as observed on pure Mg and other Mg alloys, crystallographic texture also plays a significant role in corrosion resistance. This work has hence contributed to the improvement of the understanding of the influence of the microstructure on the electrochemical behavior of a magnesium-calcium alloy
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Piccolo, Debora Regina Gastaldi. "Otimização do processo de soldagem por fricção por ponto (FSpW) de soldas de materiais similares e dissimilares de ligas leves." Universidade Federal de São Carlos, 2014. https://repositorio.ufscar.br/handle/ufscar/930.
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Previous issue date: 2014-08-07Currently there is a lot of pressure in the aeronautical and automobilistic transport section in order to reduce the fuel consumption and consequently cost and gas emissions. This measure has increased in the last years the use of light alloys, as the alluminium s alloys and of more efficient methods for joining them. Nevertheless, there is some difficult in joining these alloys using the conventional methods. The Friction Spot Welding (FSpW) is a solid state joining technique, that has great advantages regarding others joining techniques, and therefore could be a viable alternative to replace the established technologies as Resistance Spot Welding (RSW) and riveting, which are widely used by the automotive industry. The present works aims to study, through the Friction Spot Welding process (FSpW), the similar welding conditions of AA5754-H111 aluminium alloy and also the dissimilar welds between AA5754-H111 aluminium alloy and AZ31-O magnesium alloy. The influence of process parameters over the microstructure and the mechanical properties of the welded joints, as well as, the optimization of the welding process were evaluated. The joints were produced in overlap configuration through a different combination of parameters, which were established by statistical methods for design of experiments, and later submitted to mechanical and metallurgical characterization. The results proved the feasibility of joining the similar and dissimilar plates of aluminium AA5754 and magnesium AZ31 through FSpW process. The similar joints showed great results of shear strength. However, in the dissimilar joints, the utilization of a zinc interlayer, in spite of leading to a great superficial finishing, didn t effectively decrease the amount of intermetallic compounds formed in the joint as it was expected, leading to low values of shear strength.
Atualmente existe uma grande pressão no setor de transportes aeronáutico e automobilístico, a fim de reduzir o consumo de combustíveis, e consequentemente, o custo e as emissões de gases. Essa medida aumentou, nos últimos anos, o uso de ligas leves como as de alumínio e de magnésio, bem como métodos mais eficientes de uni-las. Porém, existem certas dificuldades em se unir essas ligas através de métodos convencionais de soldagem por fusão [1]. A Soldagem por Fricção por Ponto (do inglês, Friction Spot Welding - FSpW), possui várias vantagens com relação a outras técnicas de soldagem, podendo ser uma alternativa viável para substituir tecnologias, tais como Soldagem por Resistência por Ponto (RSW) e rebitagem, já muito usadas pela indústria automobilística [2] [3]. O presente trabalho visou estudar, pelo processo de FSpW, as condições de soldas similares da liga de alumínio AA5754-H111 e também de soldas dissimilares da liga de alumínio AA5754-H111 com a liga de magnésio AZ31-O, utilizando uma camada intermediária de zinco. A influência dos parâmetros de processo sobre a microestrutura e as propriedades mecânicas das juntas soldadas, assim como a otimização do processo de soldagem foram avaliadas. As soldas foram produzidas em configuração de sobreposição por diferentes combinações de parâmetros, as quais foram estabelecidas por metodologias estatísticas de planejamento de experimentos, e posteriormente submetidas à caracterização mecânica e metalúrgica. Os resultados comprovaram a possibilidade de união similar e dissimilar das chapas de alumínio AA5754 com as de magnésio AZ31 pelo FSpW. As soldas de materiais similares mostraram resultados satisfatórios de resistência ao cisalhamento. Entretanto, nas soldas de materiais dissimilares a utilização de uma camada intermediária de zinco, apesar de ter levado a um bom acabamento superficial, não reduziu efetivamente a quantidade de fases intermetálicas formadas nas juntas como o esperado, levando a valores baixos de resistência ao cisalhamento.
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Güttler, Johannes. "Field-Site Prototype for HABIT (FSP-HABIT) : Characterizing Martian Salts Prior to the ExoMars 2020 Mission." Thesis, Luleå tekniska universitet, Rymdteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-61070.
Abstract:
One of the major remaining question about Mars is its habitability - if the requirements necessary to allow for life are presently fulfilled. One of the most relevant ingredients for life, as we know it, is water. Indirect evidence of transient liquid water on Mars has been retrieved from both rover [Martín-Torres et al., 2015] and orbiter [Ojha et al., 2015]. [Martín-Torres et al., 2015] inferred the existence of an active water cycle, driven by chlorate and perchlorate salts, which are commonly found on the Martian surface, and absorb atmospheric water to form stable hydrated compounds and liquid solutions. This happens through a process called deliquescence (absorption of moisture from the atmosphere by the salts and dissolving into a liquid solution). One of the goals of HABIT is to confirm the hypothesis about the water cycle on Mars. HABIT will record the behavior of a selection of salts on Mars, and will also record Martian environmental conditions (UVdose, air and ground temperatures). The Field-Site Prototype for HABIT (FSP-HABIT) was the first prototype of HABIT deployed during field-site campaigns. Three campaigns took place during summer 2016: First, a short preparatory campaign in Abisko, Sweden, was carried out. The second campaign took place in Iceland, within the EU COST Action TD1308 ORIGINS (Origins and evolution of life on Earth and in the Universe), and the third campaign was conducted within the NASA Spaceward Bound India Program in Ladakh. After providing the corresponding background on the mission framework and the scientific background, this document covers the mechanical, electrical, and software design of the instrument. Afterwards, the steps taken to test the instrument and their results are covered, followed by a rating of the instrument and ideas for future improvements. Instruments like FSP-HABIT will enable the characterization of hygroscopic salts by their conductivity as liquid brines are good conductors, hydrated salts are poor conductors, and dehydrated salts are insulators. During the field-site campaigns, the measurements of FSP-HABIT were used to characterize the near surface environment by its temperature, pressure and relative humidity. Now, these measurements are available for comparison with microbiological studies of the water, ice and soils to characterize the habitability of the explored site. The lessons learned while designing and building FSP-HABIT can be used to inform the development of further prototypes for space missions such as HABIT.Habitability, Brines, Irradition and Temperature (HABIT)
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Silva, Fabiana Vieira da. "Notícias do apartheid: o racismo nos espaços dos jornais FSP e OESP na década de 1980." Pontifícia Universidade Católica de São Paulo, 2013. https://tede2.pucsp.br/handle/handle/12793.
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Previous issue date: 2013-06-21Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The aim of this master s degree research is to analyze a how questions related to apartheid and Brazil projection before this system were articulated in each space of newspapers Folha de São Paulo and O Estado de São Paulo between 1984 and 1990 with the aim of actualizing the construction of theme senses in the journalistic production practice and creating distances and approaches in view of a specific conception founded in notions such as neutrality and impartiality . There are meaningful similarities between the way in which newspapers OESP and FSP built apartheid-related matters, what made these communicational institutions constitute themselves in important vehicles for the characterization of racist practices as well as their perpetuation. They resorted to History to characterize evident racist practices in the social environment and introduced it as vestiges of a past related to tyrant and oligarchic ways of government. Besides the debates concerning racism in Brazil, other matters motivated PESP and FSP to keep a daily eye on Southern Africa: proposals of world economic integration overloaded by cultural values; racializing perceptions in the ways of seeing, analyzing, interpreting, and projecting the world; and the search of the constitution of a kind of both national and international society
O objetivo desta pesquisa de mestrado é analisar como questões relacionadas ao apartheid e à projeção do Brasil diante deste sistema foram articuladas em cada espaço dos jornais Folha de São Paulo e O Estado de São Paulo, entre 1984 e 1990, de modo a efetivar a construção de sentidos ao tema na prática de produção jornalística e a criação de distanciamentos, aproximações, tendo em vista uma concepção específica de jornalismo, assentada em noções como neutralidade , imparcialidade . Há semelhanças significativas entre a forma como os jornais OESP e a FSP construíram as questões relacionadas ao apartheid, o que fez com que essas instituições de comunicação se constituíssem como importantes veículos para a caracterização das práticas racistas, bem como de sua perpetuação. Recorreram à história para caracterizar as práticas racistas evidentes no meio social, e a apresentaram como resquícios de um passado , relacionadas às formas de governos tiranas , oligárquicas . Além dos debates quanto ao racismo no Brasil, outras questões motivavam OESP e FSP a lançarem seus olhares diários para a região sul da África: propostas de integração econômico-mundial sobrecarregadas por valores culturais; percepções racializantes nos modos de ver, analisar, interpretar e projetar o mundo; e pela busca da constituição de um tipo de sociedade nacional e internacionalmente
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Barros, Pablo Aronne Funchal de. "Influência do defeito tipo cunha no comportamento mecânico de juntas de liga de alumínio 2198 soldadas por fricção por ponto (FSpW)." Universidade Federal de São Carlos, 2015. https://repositorio.ufscar.br/handle/ufscar/7357.
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Submitted by Livia Mello (liviacmello@yahoo.com.br) on 2016-09-15T13:03:07Z
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
One of the main considerations in selecting materials to manufacture aircraft structures is related to weight saving [1]. In this context, the promising aluminum-lithium alloys have been receiving special attention in aerospace applications due to its attractive combination of low density, high specific strength and corrosion resistance [2-5]. Due to difficulties joining these alloys by conventional welding processes associated to their high thermal conductivity and low melting temperature, solid-state joining technologies emerge as great possibilities to simultaneously solve problems of solidification defects and increasing weight. The feasibility of Friction Spot Welding (FSpW) in joining sheets of lightweight material (e.g. aluminum alloys) places this technology as a potential replacement to the spot-like joint processes, as resistance spot welding (RSW) and laser spot welding (LSW), for application in automotive and aerospace industries [6-8]. In this work, the influence of hook defect on the lap shear strength (LSS) of AA2198-T8 friction spot welds was studied. The effects of process parameters was evaluated in terms of LSS and related to the microstructural configurations. The values of hook length measurements and the LSS were used as response in optimization process developed using the statistical tool of DoE technique with Taguchi Method. Finally it was possible to compare the hook behavior with lap shear strength results. The higher influence on the weld performance was exerted by plunge depth whereas rotational speed was found to be a less significant parameter. Through the minimization of the hook defect, a beneficial response on the weld performance was observed, which was associated to the absence of a potential site for crack nucleation. In spite of inherent discontinuities, promising results were found for aluminum joints for aerospace applications.
Uma das principais considerações na seleção de materiais para a fabricação de estruturas de aeronaves está relacionada à redução de peso [1]. Neste contexto, ligas de alumínio-lítio têm se destacado em aplicações aeroespaciais devido à sua atraente combinação de propriedades como baixa densidade, alta resistência específica e resistência à corrosão [2-5]. Devido às dificuldades para união destas ligas por processos convencionais de soldagem associadas às altas condutividades térmicas e baixas temperaturas de fusão, tecnologias de soldagem no estado sólido emergem com grande potencial para simultaneamente reduzir os defeitos de solidificação e aumento de peso. A viabilidade da Soldagem por Fricção por Ponto (do inglês – Friction Spot Welding – FSpW) para unir chapas de materiais leves posiciona esta tecnologia como potencial substituta para os processos de união por ponto, como soldagem por resistência (RSW) e soldagem a laser (LSW), para aplicação nas indústrias automotiva e aeroespacial [6-8]. O presente trabalho visou estudar a influência do defeito de cunha na resistência ao cisalhamento (RC) das juntas da liga de alumínio 2198-T8 fabricadas por FSpW. O efeito dos parâmetros de processo foi avaliado em relação à RC e relacionado com as configurações microestruturais. Os valores de comprimento de cunha e RC foram utilizados como resposta no processo de otimização desenvolvido utilizando-se a ferramenta estatística de planejamento de experimentos com o Método de Taguchi. Por fim, foi possível comparar o comportamento da cunha com os resultados de RC. A maior influência sobre o desempenho de solda foi exercida pela profundidade de penetração enquanto a velocidade de rotação foi um parâmetro menos significativo. Com a minimização da cunha obteve-se uma resposta benéfica no desempenho de solda, o que foi associado à ausência de uma região potencial para a nucleação de trincas. Apesar de descontinuidades inerentes, resultados promissores foram encontrados para juntas de alumínio para aplicações aeroespaciais.
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Lage, Sara Beatriz Miranda. "Otimização dos parâmetros de soldagem a ponto por Fricção (FSpW) da liga AlMgSc e avaliação das propriedades mecânicas estáticas e dinâmicas." Universidade Federal de São Carlos, 2017. https://repositorio.ufscar.br/handle/ufscar/9291.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Aluminum alloys are widely used in transportation industry to reduce structural weight and fuel consumption. The development of advanced alloys and more effective technologies for joining materials contribute to achieve such objectives. AlMgSc alloys emerge as an interesting option to structural applications due to low density and high mechanical performance, as well as an attractive cost. Friction spot welding (FSpW) process is a novel solid state joining technology that has proven to be suitable for joining lightweight materials. This process is carried out in a few steps and in a short time with low thermal cycles and energy consumption as well as without extra materials addition. Thus, this process is an alternative to industrial techniques such as riveting and resistance spot welding. This work presents, for the first time, the application results of FSpW on AlMgSc sheets in overlapping configuration. The effect of the process parameters, such as rotational speed, plunge depth and plunge time, was investigated in order to obtain joints with higher lap shear strength. The Taguchi method and the analysis of variance were applied to study the influence of each parameter on mechanical properties of the joints. In addition, the welds were submitted to microstructural characterization and a material flow analysis provided an initial understanding about the formation of microstructural features. Therefore, the fatigue performance was analyzed for the condition of higher lap shear strength and the S-N curve was drawn. The results indicated a good static performance of the welds, although the fatigue performance was less satisfactory. Finally, failure mechanisms of static and dynamic tests seemed to be strongly related to geometric features, such as hook, bonding ligament and microstructural transition regions.
Ligas de alumínio são amplamente utilizadas em indústrias de transporte visando a redução do peso estrutural e consumo de combustíveis. O desenvolvimento de ligas avançadas e tecnologias mais efetivas de união contribuem para o alcance de tais objetivos. Ligas do sistema AlMgSc surgem como opção interessante para utilização estrutural devido à baixa densidade e alto desempenho mecânico, aliados a um custo atrativo. O processo de soldagem a ponto por fricção (FSpW) é uma tecnologia recente de união de materiais no estado sólido, que tem se mostrado adequado para a união de ligas leves. Tal processo é realizado em poucas etapas e curto tempo, com baixos ciclos térmicos e consumo energético e sem adição de materiais extras, se mostrando, portanto, uma alternativa a técnicas utilizadas industrialmente, como rebitagem e solda a ponto por resistência. Esse trabalho apresenta, pela primeira vez, resultados de aplicação do FSpW em chapas AlMgSc sobrepostas. O efeito dos parâmetros do processo, como velocidade de rotação, profundidade e tempo de penetração da ferramenta, foi investigado visando a obtenção de soldas com maior resistência em ensaios de cisalhamento, dita condição otimizada. Para tal, foi aplicado o método Taguchi e análise de variância para estudar a importância de cada parâmetro na resistência mecânica das juntas. Além disso, as soldas foram caracterizadas microestruturalmente e uma análise do fluxo de material proporcionou um entendimento inicial acerca da formação de algumas características microestruturais. Ademais, o desempenho em fadiga foi analisado para a condição otimizada de soldagem e a curva S-N foi levantada. Os resultados obtidos apontam um bom desempenho estático das soldas, embora o desempenho em fadiga tenha sido menos satisfatório. Finalmente, os mecanismos de falha, de ensaios estáticos e dinâmicos, foram observados e se mostraram fortemente relacionados a elementos geométricos, como cunha, e linha de união, além de regiões de transições microestruturais.
CNPq: 134654/2016-1
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Pärnering, Mikael. "Utgör Privata Militära Företag en tillgång eller ett hot mot den svenska Försvarsmakten gällande återrekrytering med soldaterna ur FS21 i huvudfokus?" Thesis, Försvarshögskolan, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:fhs:diva-2210.
Abstract:
Subject: Independent essay in War Science (15 points) which debate the question if PrivateMilitary Companies is an asset or a threat to the Swedish Armed Forces regarding rerecruitmentwith focus on the soldiers of FS21.That which is investigated is the general attitude amongst soldiers who have completed theirconscript duty according to the old conscript system and now is employed in order to conducta tour abroad with Afghanistan as area of operations. Further investigated is their attitudeagainst the Swedish Armed Forces as an employer, as well as the private sector whichwant/could benefit from the skills the soldiers is possessing. Could the soldiers se themselvesleave the Armed Forces before the contract has expired in benefit of private companies whichclaim they solve similar tasks. Purpose: The purpose with this essay is to contribute with knowledge about a number ofemployed soldiers’ attitude against Private Military Companies. Further; if the soldiersbelieve the Armed Forces provide them as they think they deserve/ want in order to stay andnot leave their job in favour of PMC:s, and through it clarify what the soldiers value asemployees. Order of Approach, Method and Material: The method I’m using is a survey in whichsoldiers and squad leaders have answered the questions. The soldiers and squad leaders isfurther referred to as “the soldiers”. These soldiers were consisting of 59 males and femaleswhich were in the final stage of the preparation for their Afghanistan tour. The name of thetour is FS21. Result: According to the survey a great number of respondent soldiers claimed they wouldleave the Swedish Armed Forces in order to be employed in a PMC if the salary would proveto be better. The things that were most important to the soldiers were the colleagues and a funjob as well as the closest in command. After that the salary was vital. At the bottom,according to the soldiers, was an ethical and fair job which would be highly valued in the eyesof the public. According to the statements made by the soldiers the main reasons to stay in theArmed Forces was the group cohesion, the fellowship, the friends and the closet in command.It’s not about the Armed Forces as a department or an employer, it’s the colleagues. Conclusion: This doesn’t collide with van Doorns theory1, it merely enhance the statementwhich van Doorn expresses; that the abandonment of the conscript system will force the statemanagement out on the labour market embossed by a harsh competition of the working force.In lack of possibility to measure up with the civil salary capacity the consequence could fairlybe that the troops are recruited from marginalized groups, which threatens the Armed Forcescapacity. This could also mean that the Armed Forces train and educate individuals frommarginalized groups, as well as the ordinary male or female, and of a sudden they are mostattractive at the civil sector which appreciate military skills and knowledge and se it assomething they could benefit from.This request that the Swedish Armed Forces have an ambition to keep the soldiers it educate,a more active work in keeping the soldiers in the own organisation – merely by meeting theneeds of the soldiers. It is a constant necessitate re-recruiting every day, not when thecontracts reaches its due date.Ämne: Självständigt arbete i Krigsvetenskap (15HP) som behandlar frågan huruvida PrivataMilitära Företag är en tillgång eller ett hot mot den svenska Försvarsmakten gällandeåterrekrytering med soldaterna ur FS21 i huvudfokus. Med återrekrytering menas förnyelse avkontrakt som löper mot sitt slut.Det som undersöks är bland annat den generella inställningen hos soldater som har gjortmilitärtjänst enligt det gamla värnpliktssystemet och nu är anställda med målsättning attgenomföra utlandsmission med Afghanistan som operationsområde. Vidare undersöks derasinställning till Försvarsmaktens personalpolitik samt deras inställning till den privata sektornsom vill/kan dra nytta av kompetensen som soldaterna besitter. Skulle dessa soldater kunnatänka sig att lämna Försvarsmakten till förmån för privata företag som säger sig kunna lösaliknande uppgifter, och detta innan kontraktet med Försvarsmakten löpt ut? Syfte: Syftet med denna uppsats är att bidra med kunskap om inställningen hos anställdasoldater ur FS21. Hur är deras inställning till Privata Militära Företag? Vidare att undersökaom Försvarsmakten, enligt dessa soldater, erbjuder dem det som önskas/anses skäligt för attinte lämna sin anställning till förmån för PMF och därigenom klargöra vad det är soldaternavärderar som anställd. Genomförande, Metod, Material: Metoden jag nyttjat mig av är en respondentundersökninggenom en enkät. Enkätundersökningen har genomförts där soldater och gruppchefer har svaratpå frågorna. Soldaterna och gruppcheferna benämns genom uppsatsen som enbart”soldaterna”. Dessa soldater utgjordes av 59 män och kvinnor som då var i slutskedet på sinutbildning och i sina förberedelser för utlandsmission till Afghanistan. Missionens benämningär FS21. Resultat: Genom enkätundersökningen påpekade väldigt många av de tillfrågade soldaternaatt de skulle lämna Försvarsmakten för att istället ta anställning inom ett PMF om lönenvisade sig vara bättre. Det som var viktigast för soldaterna var arbetskamrater och ett roligtjobb samt den närmaste chefen. Därefter var lönen att betrakta som vital. På näst sista platshamnade enligt soldaterna ett etiskt och korrekt arbete som i allmänhetens ögon är högtvärderat. Enligt de uttalanden som soldaterna gjort i fritextsvaren så är det främstgruppsammanhållningen, samhörigheten, kamraterna och den närmsta chefen som äranledningen till att stanna. Det är inte Försvarsmakten som myndighet eller arbetsgivare i sig,utan kollegorna. Slutsatser: Detta krockar inte med van Doorns teori2, utan snarare förstärker det påståendetsom van Doorn uttrycker om att övergivandet av värnpliktssystemet medför att statsledningentvingas ut på en arbetsmarknad präglad av en hård konkurrens om arbetskraften. I brist avmöjligheter att följa de civila lönetrenderna kan följderna bli att manskapet kan komma attrekryteras ur marginaliserade grupper och därigenom äventyra försvarskraften. Det kan ävenbetyda att Försvarsmakten tränar upp och utbildar individer ur marginaliserade grupper, tillikasom gemene man och kvinna, så att dessa plötsligt blir attraktiva hos den civila sektorn somser soldaternas kunskap och militära färdigheter som något de kan dra nytta av.Det krävs av Försvarsmakten att det finns en ambition att behålla de soldater som utbildas, ettmer aktivt arbete i att behålla soldaterna i de egna leden – främst genom att möta soldaternasbehov.Det är en ständig nödvändighet att återrekrytera varje dag, inte enbart när kontrakten börjarnärma sig sina slut.
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FERNANDES, Camila Albuquerque. "Estudo do desempenho mecânico e microestrutural de uniões da liga de alumínio, AA6061-T6, por solda a ponto por fricção (FSpW)." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/18599.
Abstract:
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Dissertação CAMILA ALBUQUERQUE FERNANDES 2016.pdf: 2707069 bytes, checksum: 1af5a8e892dd9aa2682c79f98c6cde09 (MD5)Made available in DSpace on 2017-04-19T18:29:57Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação CAMILA ALBUQUERQUE FERNANDES 2016.pdf: 2707069 bytes, checksum: 1af5a8e892dd9aa2682c79f98c6cde09 (MD5) Previous issue date: 2016-07-29
Solda a Ponto por Fricção (Friction Spot Welding – FSpW) é um processo relativamente novo de soldagem desenvolvido e patenteado pelo GKSS na Alemanha, que visa complementar e/ou substituir tecnologias de uniões de soldagem convencionais. Essa nova tecnologia de soldagem se dá pela união no estado sólido, onde duas ou mais chapas são unidas através da transferência de energia térmica e mecânica que é gerada pela rotação da ferramenta. O presente trabalho visou avaliar a aplicabilidade da união da liga de alumínio 6061-T6 pela técnica de Solda a Ponto por Fricção. Essas soldas foram produzidas em configuração de sobreposição utilizando condições de soldagens variadas, por meio de diferentes combinações de velocidade de rotação, profundidade de penetração e velocidade de penetração; os quais foram estabelecidos através de uma análise estatística, utilizando como ferramenta o Box-Behnken. A integridade da junta soldada foi avaliada através dos efeitos dos parâmetros de processo, na geometria e na microestrutura da junta, e também no desempenho mecânico. Realizou-se também a otimização do processo de soldagem e um estudo sobre o comportamento de fratura das soldas submetidas a um esforço de cisalhamento. Os resultados mostraram que a melhor combinação de parâmetros foi encontrada na condição de soldagem: 130 rpm, 4,0 mm/s e 1,4 mm, com um valor médio de resistência ao cisalhamento de 6243,29 N, com boa reprodutibilidade. O botão da solda é constituído por três elementos geométricos que se mostraram inerentes ao processo: cunha, união principal e união secundária. Estes elementos mostraram possuir forte influência sobre o desempenho mecânico.
Friction Spot Welding (FSpW) is a relatively new welding process patented by GKSS in Germany. This new welding technology is given by the joining in a solid state, in which two or more plates are joined by thermal and mechanical energy transfer that is generated by the rotation of the welding tool. The aim of this work is to study the integrity of the welds of AA6061-T6, by the FSpW process. These welds were produced in an overlapping configuration using different welding conditions, through different combinations of rotational speed, depth of penetration and penetration speed, which were set through a statistical approach using the Box-Behnken. The integrity of the welded joint was evaluated by the effects of process parameters on geometry and microstructure of the joint, and also in the mechanical performance. It was also performed the optimization of the welding process and a brief study on the fracture behavior of the welds subjected to a shear stress. The results showed that the best combination of parameters was found in the welding condition: 130 rpm 4.0 mm / s and 1.4 mm with an average value of the shear strength of 6243.29 N, with good reproducibility. The metallurgical investigation revealed three geometric elements that are inherent to the process: primary union and secondary union and hook. These elements were shown to have strong influence on the mechanical performance.
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ITHARAJU, RAJESWARI R. "FRICTION STIR PROCESSING OF ALUMINUM ALLOYS." UKnowledge, 2004. http://uknowledge.uky.edu/gradschool_theses/322.
Abstract:
Friction stir processing (FSP) is one of the new and promising thermomechanical processing techniques that alters the microstructural and mechanical properties of the material in single pass to achieve maximum performance with low production cost in less time using a simple and inexpensive tool. Preliminary studies of different FS processed alloys report the processed zone to contain fine grained, homogeneous and equiaxed microstructure. Several studies have been conducted to optimize the process and relate various process parameters like rotational and translational speeds to resulting microstructure. But there is only a little data reported on the effect of the process parameters on the forces generated during processing, and the resulting microstructure of aluminum alloys especially AA5052 which is a potential superplastic alloy. In the present work, sheets of aluminum alloys were friction stir processed under various combinations of rotational and translational speeds. The processing forces were measured during the process and the resulting microstructure was analyzed using TEM. The results indicate that the processing forces and the microstructure evolved during FSP are sensitive to the rotational and translational speed. It is observed that the forces generated increase with the increasing rotational speed. The grain refinement was observed to vary directly with rotational speed and inversely with the translational speed. Also these forces generated were proportional to the grain refinement i.e., greater refinement of grains occurred at lower forces. Thus the choice of process parameters especially the rotational speed has a significant effect on the control and optimization of the process.
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Sobel, Felicitas [Verfasser], Kerstin Ute [Akademischer Betreuer] Amann, and Christoph [Gutachter] Daniel. "Die renale Phänotypisierung der FSP-1 knockout Maus / Felicitas Sobel ; Gutachter: Christoph Daniel ; Betreuer: Kerstin Ute Amann." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2020. http://d-nb.info/1217065229/34.
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Gunter, Cameron Cornelius. "Feasibility of Friction Stir Processing (FSP) as a Method of Healing Cracks in Irradiated 304L Stainless Steels." BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/6111.
Abstract:
The current US fleet of nuclear reactors has been in service for three decades. Over this period, existing welds in stainless steel (SS) shrouds have sustained stress corrosion cracking (SCC) and are in need of repair. Additionally, helium has formed interstitially as a byproduct of proton bombardment. Current repair technology, such as TIG welding, puts extreme amounts of heat into the material and allows for interstitial helium atoms to aggregate and form bubbles/voids at grain boundaries. This significantly weakens the material, proving to be a very counterproductive and ineffective repair technique. Much study has been done on friction stir processing (FSP), but none has explored it as an enabling repair technology for use in nuclear applications. Because of its relatively low energy input as a solid state joining technology, it is proposed that FSP could effectively heal SCCs in these existing welds without the negative side effect of helium bubble formation. A spread of speeds and feeds were initially tested using a PCBN-W-Re tool on 304L SS. Six of these parameter sets were selected as representations of high, medium, and low temperature-per-power outputs for this research: 2 IPM-80 RPM, 2 IPM-150 RPM, 4 IPM-150 RPM, 4 IPM-250 RPM, 6 IPM-125 RPM, and 6 IPM-175 RPM. These varied parameter sets were tested for their tensile, micro-hardness, and corrosion resistant properties. In general, the lower IPM and RPM values resulted in higher ultimate tensile strengths (UTS). Higher IPM and RPM values resulted in tunnel, pin hole, and surface void defects. These defects caused premature failure in tensile tests and could often be identified through microscopy. Micro-hardness testing demonstrated a strong correlation per the Hall-Petch relationship – finer grain sizes resulted in higher yield strength (hardness values) of the material. The tool temperature during FSP was a good indicator of the expected hardness – lower temperatures resulted in higher hardness values. Corrosion testing was performed with a 1000-hour alternate immersion test in a room temperature 3.5% NaCl solution. With these testing parameters, the results demonstrated that FSP had no effect on the corrosion resistance of 304L SS under these conditions.
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Perez, Raphaël. "Analyzing and modelling the genetic variability of aerial architecture and light interception of oil palm (Elaeis guineensis Jacq)." Thesis, Montpellier, SupAgro, 2017. http://www.theses.fr/2017NSAM0001/document.
Abstract:
Cette étude propose d’analyser l’influence de l’architecture du palmier à huile sur sa capacité à intercepter la lumière, en se basant sur des reconstructions 3D de palmiers et en établissant un bilan radiatif sur ses structures végétales reconstruites in silico. Le premier objectif de l’étude était de caractériser et modéliser la variabilité génétique de l’architecture du palmier à huile et de son interception lumineuse. Dans un deuxième objectif l’amélioration potentielle de l’interception de la lumière et de l’assimilation carbonée a été évaluée en modifiant les traits morphologiques et géométriques des feuilles et des idéotypes architecturaux de palmiers à huile ont été proposés.Des relations allométriques ont été utilisées pour modéliser les traits architecturaux en fonction de gradients ontogénétique et de topologie des feuilles dans la couronne. La méthode permet de reconstruire des palmiers à huile virtuels à différents âges au cours du développement. De plus, l’approche allométrique a été couplée à des modèles à effets mixtes pour intégrer au travers de paramètres la variabilité entre et au sein des cinq progénies. Le modèle permet ainsi de simuler les spécificités architecturales des cinq progenies en incluant les variabilités entre individus observés. Le modèle architectural, paramétré pour les différentes progénies, a ensuite été implémenté dans AMAPstudio pour générer des maquettes 3D de palmiers et ainsi estimer leur interception lumineuse, de l’individu à la parcelle entière.Les résultats de ces analyses ont révélé des différences significatives entre et au sein des progenies, dans la géométrie des feuilles (longueur du pétiole, densité de folioles sur le rachis, et courbure du rachis) et dans la morphologie des folioles (gradients de longueurs et largeurs le long du rachis). La comparaison virtuelle des différentes progénies ont aussi montré des efficacités distinctes de l’interception lumineuse.Des analyses de sensibilité ont ensuite été réalisées pour identifier les traits architecturaux influençant l’interception lumineuse et l’assimilation potentielle à différents âges de la plante. Les paramètres les plus sensibles au cours du développement furent ceux reliés à la surface totale foliaire (longueur des rachis, nombre de folioles, morphologie des folioles), mais les attributs géométriques plus fins de la feuille ont montré un effet croissant avec la fermeture de la canopée. Sur un couvert adulte, l’optimum en assimilation carbonée est atteint pour des indices de surfaces foliaires (LAI) entre 3,2 et 5,5 m2.m−2, avec des feuilles érigées, de courts pétioles et rachis et un nombre important de folioles sur le rachis. Quatre idéotypes architecturaux pour l’assimilation carbonée ont été proposés et présentent des combinaisons spécifiques de traits géométriques, limitant l’ombrage mutuel des plantes et optimisant la distribution de la lumière dans la couronne.En conclusion, le modèle 3D de palmiers à huile, dans sa conception et son application, a permis de détecter les traits architecturaux génétiquement déterminés et influençant l’interception lumineuse. Ainsi, le nombre limité de traits dégagés par l’analyse de sensibilité ainsi que les combinaisons de traits révélées au travers des idéotypes pourraient être pris en compte dans de futurs programmes de sélection. En perspective, des travaux dédiés à intégrer dans ce modèle d’autres processus physiologiques, tels que la régulation de la conductance stomatique et le partitionnement du carbone dans la plante, sont à envisager. Ce nouvel FSPM pourrait alors être utilisé pour tester différents scénarii, comme par exemple dans un contexte de changement climatique avec de faibles radiations et des périodes de sécheresse fréquentes. De même, ce modèle pourrait être utilisé pour étudier différentes configurations de plantation et des systèmes de cultures intercalaires, et ainsi proposer de nouveaux idéotypes multicritèresIn this study we proposed to investigate the influence of oil palm architecture on the capacity of the plant to intercept light, by using 3D reconstructions and model-assisted evaluation of radiation-use efficiency. The first objective of this study was to analyse and model oil palm architecture and light interception taking into account genetic variability. A second objective was to explore the potential improvements in light capture and carbon assimilation by manipulating oil palm leaf traits and propose architectural ideotypes.Allometric relationships were applied to model these traits according to ontogenetic gradients and leaf position within the crown. The methodology allowed reconstructing virtual oil palms at different stages over plant development. Additionally, the allometric-based approach was coupled to mixed-effect models in order to integrate inter and intra progeny variability through progeny-specific parameters. The model thus allowed simulating the specificity of plant architecture for a given progeny while including observed inter-individual variability. The architectural model, parameterized for the different progenies, was then implemented in AMAPstudio to generate 3D mock-ups and estimate light interception efficiency, from individual to stand scales.Significant differences in leaf geometry (petiole length, density of leaflets and rachis curvature) and leaflets morphology (gradients of leaflets length and width) were detected between and within progenies, and were accurately simulated by the modelling approach. Besides, light interception estimated from the validated 3D mock-ups showed significant variations among the five progenies.Sensitivity analyses were then performed on a subset of architectural parameters to identify the architectural traits impacting on light interception efficiency and potential carbon assimilation over plant development. The most sensitive parameters over plant development were those related to leaf area (rachis length, number of leaflets, leaflets morphology), but fine attribute related to leaf geometry showed increasing influence when canopy got closed. In adult stand, optimized carbon assimilation was estimated on plants presenting a leaf area index (LAI) between 3.2 and 5.5 m2.m−2, with erected leaves, short rachis and petiole and high number of leaflet on rachis. Four architectural ideotypes for carbon assimilation were proposed based on specific combinations of organs geometry, limiting mutual shading and optimizing light distribution within plant crown.In conclusion, this study highlighted how a functional-structural plant model (FSPM) can be used to virtually explore plant biology. In our case of study, the 3D model of oil palm, in its conception and its application, permitted to detect the architectural traits genetically determined and influencing light interception. The limited number of traits revealed in the sensitivity analysis and the combination of traits proposed through ideotypes could guide further breeding programs. Forthcoming work will be dedicated to integrate in the modeling approach other physiological processes such as stomatal conductance and carbon partitioning. The improved FSPM could then be used to test different scenarios, for instance in climate change context with low radiations or frequent drought events. Similarly, the model could be used to investigate different planting patterns and intercropping systems, and proposed new multi-criteria ideotypes of oil palm
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Verástegui, Roger Navarro. "Estudo de uniões dissimilares alumínio-soldas por "Solda Ponto por Fricção e mistura mecânica com preenchimento do furo" (Friction Spot Welding - FSpW)." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/61398.
Abstract:
O presente trabalho estuda uniões entre chapas de aço DP600 e chapas das ligas de alumínio AA 6181–T4 e AA 5754–H22, obtidas através do processo Friction Spot Welding (FSpW). A soldagem de materiais dissimilares é um dos grandes desafios para a engenharia, pois as propriedades de distintos materiais são muito diferentes na maioria das vezes, o que dificulta a realização deste tipo de união pelos métodos convencionais de soldagem com fusão. O processo FSpW requer menos energia que os processos de soldagem convencionais, não produz fumos, radiação ou resíduos. Permite obter a união de materiais no estado sólido, sendo, portanto potencialmente indicado para uniões dissimilares. Por ser um processo muito mais “limpo” que os usados convencionalmente, pode contribuir significativamente com uma grande preocupação mundial que é a sustentabilidade. A influência de um revestimento galvanizado nas chapas de aço para a qualidade das uniões resultantes foi avaliada realizando-se as operações de soldagem com as chapas de aço nas condições com e sem a camada galvanizada. O método estatístico de Taguchi foi utilizado para definir os parâmetros de soldagem que maximizassem a resistência das juntas para cada condição de ensaio, sendo a qualidade das juntas obtidas definida pela resistência da união ao ensaio de cisalhamento. Durante a soldagem, a temperatura em pontos específicos foi adquirida e, posteriormente, as juntas foram submetidas à análise metalográfica e de composição química por EDS. A partir da análise das macro e microestruturas dos corpos de prova com melhor resistência ao cisalhamento, foi possível associar diferentes parâmetros de processo e mecanismos de união para cada tipo de junta. O estudo comprovou a possibilidade de obtenção de uniões dissimilares entre o aço e as duas ligas de alumínio através do processo FSpW, especialmente quando utilizou-se o aço com a camada galvanizada que apresentou modo de união mais eficaz.This work aims at the study of welding DP600 steel to AA6181-T4 and AA5754-H22 aluminum alloys plates by Friction Spot Welding (FSpW). Welding of dissimilar materials is a great challenge for engineering due to the diverse properties of different materials, that difficult welding by conventional methods of fusion. FSpW is a joining method that requires lower energy than conventional welding processes and produces no hazard gases or radiation. It allows solid state joining that is potentially indicated to dissimilar materials joining, and contributes significantly to sustainability, because the process can be considered “cleaner” that those used conventionally. The influence of the galvanized layer on the joint performance with the steel plates on was tested using steel plates with and without this coating. The Taguchi statistic method was employed to define the welding process parameters that produce higher shear stress resistance to each test condition, so the welding joints quality was defined based on the union resistance to shear. During the welding operation the temperature at given positions was acquired and the resulting joints were submitted to metallographic and chemical composition analysis. From the analysis of specimen that showed best stress test performance to each joint condition, it was possible to associate different process parameters and joint mechanisms to each condition. The study demonstrates the feasibility of joining the steel to both aluminum alloys using FSpW. The best shear test results were obtained with the presence of a galvanized layer.
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Fischer, Vanessa Fischer da Silveira. "Aplicação do processo de soldagem a ponto por fricção (FSpW) entre juntas dissimilares de aço e liga de alumínio para aplicações automotivas." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/117777.
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O processo de união entre ligas de alumínio e aços é complexo, devido às suas diferentes propriedades físicas e mecânicas, bem como pela formação de grande quantidade de compostos intermetálicos frágeis, o que dificulta a realização deste tipo de união pelos métodos convencionais de fusão. O processo de Soldagem a Ponto por Fricção (Friction Spot Welding - FSpW) é destinado à soldagem de juntas sobrepostas, adequado para união de materiais leves, e.g. ligas de alumínio e de magnésio para aplicações estruturais. A gama de componentes e materiais para os quais o FSpW pode ser aplicado está em contínua expansão, garantindo ao processo potencial para se tornar uma tecnologia industrial significativa. Por ser um processo que ocorre em estado sólido, apresenta algumas vantagens em relação aos métodos convencionais de fusão. O baixo aporte térmico associado a essas técnicas de soldagem exibe grande potencial para reduzir ou até mesmo inibir a formação da camada de compostos intermetálicos, sendo, portanto potencialmente indicado para união de materiais dissimilares. Neste trabalho foi feito um estudo da viabilidade da soldagem dissimilar entre as ligas de Alumínio AA5454-H22 e aço automotivo HX340-LAD-Z através do processo FSpW. As juntas soldadas foram analisadas mecânica e metalurgicamente, tendo como objetivo avaliar os efeitos dos parâmetros de processo na microestrutura, na geometria e no desempenho mecânico da junta, além de buscar a otimização do processo para os materiais em estudo. A relação entre a qualidade da junta e os parâmetros do FSpW foi estudada utilizando o Método Taguchi, por meio do estudo do comportamento das soldas sob solicitação monotônica de cisalhamento. Os resultados obtidos demonstram que soldas de boa qualidade e reprodutibilidade podem ser produzidas com este processo. Contudo, a presença de um filme intermetálico composto por fases ricas em Al, tais como Fe2Al5 e FeAl3, na interfaces das soldas, afeta significativamente o comportamento em fratura das juntas e, consequentemente, seu desempenho mecânico.The joining process of aluminium and steel is very complex in view of the differences between their physical and mechanical properties, as well as the formation of great amounts of brittle intermetallic compounds at the joint interface, which make it difficult to join those materials using conventional fusion welding techniques. Friction Spot Welding (FSpW) is a suitable joining process, which produces high quality overlap joints of lightweight materials, e.g., aluminium and magnesium alloys for structural applications. The range of components and materials for which FSpW can be used is continuously expanding, ensuring great potential to the process, which became nowadays a significant industrial technology. As a solid state joining process FSpW offers some advantages relative to conventional fusion welding techniques. The low heat input involved in this process has great potential to reduce, or even to inhibit, the formation of the intermetallic layer, making it, therefore, suitable to join dissimilar materials. In this work a study of feasibility of dissimilar FSpW between the aluminium alloy 5454-H22 and the automotive steel HX340LAD-Z was performed. The welded joints were assessed mechanically and metallurgically aiming evaluate the process parameter effects on the microstructure, geometry and mechanical performance of the joint, besides searching the process optimization for the materials in question. The relationship between the joint quality and the FSpW process parameters was analysed using Taguchi’s Method, studying the behaviour of the joint under shear load. The results revealed that sound welds between AA5454-H22 and HX340LAD-Z with high strength and reproducibility can be produced with using this process. It was found that the presence of an intermetallic film compounded by Al-rich phases, such as Fe2Al5 and FeAl3, at the joint interface, plays a fundamental role on the fracture behaviour of the joints and thus, and on its mechanical behaviour.
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Oliveira, Pedro Henrique Freiria de. "Estudo das propriedades e desempenho mecânico de juntas soldadas por fricção pontual de poli (metacrilato de metila) (PMMA)." Universidade Federal de São Carlos, 2012. https://repositorio.ufscar.br/handle/ufscar/899.
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Previous issue date: 2012-10-05Universidade Federal de Minas Gerais
Polymeric components have been replacing traditional materials such as glass or metals in a wide range of applications due to their advantages, such as optimized specific strength (weight-to-strength ratio), reduced fabrication time and costs, and design flexibility. The increasing use of polymeric materials in engineering requires efficient and environmental friendly fabrication and processing technologies. Initially developed for metals, the Friction Stir Spot Welding (FSSW) is a joining technique with short process cycles, low energy consumption and no need of consumables. Friction Stir Spot Welding has excellent performance in welding of lightweight alloys, showing promising results in thermoplastic welding. This study investigates the relationships between friction stir spot welding parameters (tool rotational speed, plunge rate and dwell time) and weld properties (joint geometry, process temperature, microstructure, lap shear resistance and failure mechanisms) in polymethylmethacrylate (also known as PMMA) single-spot joints. PMMA friction stir spot welds showed similar mechanical performance in comparison to other current welding techniques, with equal or shorter welding cycle times. Differential scanning calorimetry and gel permeation chromatography analysis demonstrated that polymer degradation level in the weld region was negligible. The statistical models proposed for FSSW of PMMA showed good repeatability and reproducibility for the investigated material and welding ranges. Moreover, the feasibility of the Friction Spot Welding (FSpW) a new joining technology developed as a further improvement of the friction stir spot welding was successfully demonstrated in thermoplastic polymers for the first time worldwide. Sound FSpW-single lap joints on PMMA were produced and their properties studied within an exploratory study.
A busca por eficiência econômica e tecnologias ecologicamente corretas tem sido observada em praticamente todos os setores da produção industrial, desde o desenvolvimento de materiais, design de produtos e inclusive na área da soldagem. A soldagem ponto por fricção e mistura mecânica, FSSW (do inglês Friction Stir Spot Welding) e a Friction Spot Welding FSpW são técnicas de soldagem recentes e que têm sido amplamente empregadas na união de ligas metálicas leves, em que as soldas geralmente apresentam excelentes propriedades mecânicas. Além disso, ciclos de soldagem curtos, baixo consumo de energia e ausência de necessidade de adição de material ou elementos de soldagem são características positivas encontradas nesses novos processos. Na área de materiais poliméricos, entretanto, este é um novo e promissor assunto. Neste trabalho buscou-se investigar a relação entre os parâmetros do processo de soldagem por FSSW (velocidade de rotação da ferramenta, taxa de penetração e tempo de recalque) e as propriedades das juntas (geometria da solda, máxima temperatura processual, área afetada termicamente, resistência mecânica ao cisalhamento sob tensão e mecanismos de fratura) em placas de poli (metacrilato de metila). Foi possível observar a formação de juntas com resistência mecânica ao cisalhamento semelhante a outros processos atualmente utilizados na indústria, com tempos de ciclo de soldagem iguais ou inferiores a esses processos. As análises via calorimetria diferencial exploratória (DSC) e cromatografia por permeação em gel (GPC) demonstraram que os níveis de degradação termomecânica encontrados nas amostras foram insignificantes. A modelagem estatística do processo demonstrou a boa repetibilidade e reprodutibilidade dentro das condições estudadas. Nesse trabalho, também foi investigado através de um estudo exploratório, pela primeira vez, a viabilidade da nova técnica FSpW na soldagem de termoplásticos, demonstrando, com sucesso, a capacidade de obtenção de juntas de boa qualidade em PMMA.
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Rojo, Renê Esteban. "Em pauta, as eleições : análise da cobertura eleitoral da FSP e OESP nas eleições de 2002 em São Paulo." Universidade Federal de São Carlos, 2006. https://repositorio.ufscar.br/handle/ufscar/1454.
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Previous issue date: 2006-03-29The present dissertation made a study of case about media s covering over the paulista s government elections of 2002. Therefore, we made use of the newspapers Folha de S. Paulo and O Estado de S. Paulo in two specific dimensions of bibliographical analysis: 1) the impact of medias on political representation and electoral debate; and 2) the centrality of mass media in the contemporary democratic societies. The central analytical presuppositions used here in order to understand the degree of neutrality, the independence of those medias and its covering strategies, were the conceptions of frame and agenda-setting function, which admit the unintentional power of the mass communication agents in their work of presentation and qualification of subjects that people will transform as public debate s object for a certain period of time. After the analysis of the data collected during the four months that had preceded the elections, it was observed that those pointed out that both periodicals: a) carry different standards of communicating the news; b) display all competitive candidates equally; c) develop an electoral thematic universe which transpass the dispute limits; d) give limits range of news and tend not to interpret those when the subject is approached.
A presente dissertação realizou um estudo de caso sobre a cobertura das eleições para o governo paulista de 2002. Para tanto, foram utilizados os jornais Folha de S. Paulo e O Estado de S. Paulo, relacionados a duas dimensões específicas de análise bibliográfica, qual seja, o impacto das mídias na representação política e no embate eleitoral e a centralidade da mídia de massas nas sociedades democráticas comtemporâneas. Os pressupostos teóricos centrais aqui enveredados para se perceber o grau de neutralidade, de independência e as estratégias de cobertura despendidas por estes veículos, foram as noções de enquadramento e de agendasetting, que admitem o poder não-intencional dos meios de comunicação de massas em apresentar e adjetivar os temas que as pessoas transformarão em objeto de debate público durante um determinado período de tempo. Após a análise dos dados captados durante os quatro meses que antecederam as eleições, estes apontaram na direção de que ambos os jornais: a) carregam padrões de noticiabilidade diferenciados; b) dispõem de forma equivalente a valoração sobre os candidatos competitivos; c) tecem um universo de cobertura temático-eleitoral que transborda os limites da disputa e d) propõem uma limitação noticiosa e pouco interpretativa ao enquadrar esse assunto.
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Herédia, Leila da Cruz Gonçalves. "A retórica da capa: a reeleição de FHC e de Lula na primeira página de O Globo e FSP." Universidade Federal de Juiz de Fora (UFJF), 2008. https://repositorio.ufjf.br/jspui/handle/ufjf/2842.
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Muito mais que oito anos separam as reeleições dos dois presidentes do período pós-redemocratização. Para além das inúmeras diferenças entre o sociólogo Fernando Henrique Cardoso (PSDB) e o ex-metalúrgico Luiz Inácio Lula da Silva (PT), que conquistaram um segundo mandato em 1998 e 2006, respectivamente, está a forma como ambos foram tratados pela chamada grande mídia nacional, representada aqui nesse estudo por Folha de SP e O Globo. A proposta é mostrar como a sucessão foi tratada na capa desses dois jornais, que concentram a maior circulação no Brasil. O foco está nos 90 dias que antecederam a eleição. A partir da avaliação das aparições correlacionadas às valências são aplicados os conceitos de Toulmin (2001) e Perelman (1996) ao conjunto discursivo da primeira página. O objetivo é verificar, ainda, o pacote de argumentos que foi vendido ao (e)leitor.
Much more than eight years separate the reelections of the two presidents in Brazilian post-redemocratization period. Beyond the countless differences between the sociologist Fernando Henrique Cardoso (PSDB) and the former-metallurgist Luiz Inácio Lula da Silva (PT), who conquered a second mandate in 1998 and 2006, respectively, is the way that both were treated by the so-called great national media, represented here in this study by Folha de SP and O Globo. The proposal is to show how the succession was treated on the cover of those two newspapers, which concentrate the largest circulation in Brazil. The focus is in the 90 days that preceded the election. Starting from the analyses of the appearances correlated to the impact evaluation (positive, negative or neutral) of the news the concepts of Toulmin (2001) and Perelman (1996) are applied to the discursive group of the first page. The objective is, still, to verify the package of arguments which were sold to the reader (elector).
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Smith, James R. "Effect of fluid mesh truncation on the response of a Floating Shock Platform (FSP) subjected to an Underwater Explosion (UNDEX)." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1999. http://handle.dtic.mil/100.2/ADA371731.
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Thesis (M.S. in Mechanical Engineering) Naval Postgraduate School, September 1999."September 1999:. Thesis advisor(s): Young S. Shin. Includes bibliographical references (p. 71-72). Also Available online.
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Schlehuber, Eva. "Die Strahlentherapie der Periarthropathia humeroscapularis (PHS), der Epicondylopathia humeri (EPH) und des schmerzhaften plantaren Fersensporns (FSP) mit 6-MV-Photonen." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=971990123.
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Vera, Yévenes Carolina Alejandra. "Estudio preliminar de la variabilidad genómica de la región Fsp del gen de la proteína de fusión del virus distemper canino." Tesis, Universidad de Chile, 2014. http://repositorio.uchile.cl/handle/2250/132152.
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Memoria para optar al Título Profesional de Médico VeterinarioEl Distemper Canino (DC) es una de las principales enfermedades infecciosas en canes domésticos. La introducción de vacunas de virus vivos modificados ha ayudado a mantener controlada la enfermedad. No obstante, en las últimas décadas se ha observado un aumento de la incidencia de esta patología en poblaciones de canes de todo el mundo, desarrollándose inclusive en animales vacunados. Los linajes de virus distemper canino (VDC) circulantes en el mundo se han descrito en base al análisis de la hemaglutinina (H) debido a que posee un alto grado de variabilidad genética. Sin embargo, nuevos estudios han detectado mayores variaciones en la secuencia aminoacídica de una región de la proteína de fusión (F). Para determinar la variabilidad de las cepas de campo en comparación con las vacunas y las cepas de otros linajes, en esta memoria de título se analizó la variabilidad genómica de la región Fsp del gen de la proteína de fusión de VDC. Para esto se implementó una técnica de reacción en cadena de la polimerasa con transcripción reversa (RT-PCR) capaz de amplificar esta región variable, la cual fue identificada mediante su secuencia nucleotídica. Estas secuencias se compararon con cepas vacunales y con cepas de campo de los linajes conocidos. Además, se construyó un árbol filogenético para esta región variable. Los resultados de la comparación de nucleótidos arrojaron que las secuencias de las cepas de campo tienen mayor homología a la cepa vacunal Onderstepoort y según la filogenia pertenecerían al linaje América 1. PALABRAS
FIV 121014019102010
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Chan, Chun Yip. "Friction stir processing of aluminium-silicon alloys." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/friction-stir-processing-of-aluminiumsilicon-alloys(0ffc1328-0a9d-4220-ab31-ee52173ed3a1).html.
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Friction Stir Processing (FSP) has the potential for locally enhancing the properties of Al-Si alloy castings, for demanding applications within the automotive industry. In this thesis, the effect of FSP has been examined on three different cast Al-Si alloys:i) A Hypoeutectic Al-8.9wt%Si Alloyii) A Hypereutectic Al-12.1wt%Si Alloyiii) A Hypereutectic Al-12.1wt%Si-2.4wt%Ni AlloyThe influence of different processing parameters has been investigated at a fundamental level. Image analysis of particle size distributions and growth method of tessellation were used to quantify the level of particle refinement and the homogeneity of the second phase spatial distribution. Stop-action experiments were also carried out, to allow the microstructural changes around the tool during FSP to be studied. Two computer models have been explored, in order to predict the temperature distribution and the material flow behaviour. Furthermore, the stability of the microstructure of the friction stir processed material was studied after being heat treated at elevated temperatures. The changes in particle size and grain structure were examined, hardness measurements were taken across the PZ, and tensile testing were carried out at room and elevated temperatures.After FSP, the microstructure of the cast Al-Si alloys was greatly refined. However, differences in microstructure have been observed throughout the PZ, which tended to be better refined and distributed on the advancing side, than the retreating side of the PZ. Changing the processing parameters also influenced the size and spatial distribution of the second phase particles. By studying the changes in microstructure around the tool from the stop-action experiments, and comparing the results to the thermal distribution and material flow behaviour predicted by the computer models, it has been shown that the flow stress, pitch, and temperature of processing, all needed to be considered, when determining the effects that FSP have on the microstructure. FSP caused very little changes to the hardness of the material, while tensile properties were greatly improved, due to the elimination of porosity and refinement of large flawed particles. In terms of the stability of the microstructure after FSP, particle coarsening and abnormal grain growth has been observed during high temperatures heat treatment. Furthermore, the Al2Cu phase was found to dissolve into solid solution at elevated temperatures, so GPZs and solute clustering can then develop within the alloy during natural ageing.
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Leal, Letícia Pegoraro. "Estudo comparativo do efeito da aplicação de zinco como camada intermediária em soldas dissimilares produzidas por soldagem a ponto por fricção (FSpW) entre as ligas AA5754 E AZ31." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/131027.
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Neste trabalho foi realizado um estudo comparativo entre juntas dissimilares produzidas pelo processo FSpW sem e com a utilização de Zn como metal intermediário tendo a finalidade de investigar a eficácia da adição deste metal no comportamento mecânico das juntas, bem como avaliar sua influência nas características microestruturais das juntas soldadas. As juntas foram produzidas com ligas de Al AA5754-H24 e Mg AZ31-O, de particular interesse do setor automotivo. Nas condições de soldagem com metal intermediário, chapas de Al revestido com Zn por galvanização foram usadas. As propriedades mecânicas das juntas foram avaliadas através de ensaios com carregamento quasi-estáticos e dinâmicos, sendo então correlacionados com as características microestruturais. Através das análises constatou-se que a aplicação de Zn como metal intermediário mostrou-se efetiva na redução do volume de compostos intermetálicos formados na interface da solda e consequentemente, obteve-se um aumento do desempenho mecânico de cerca de 48 % no ensaio de cisalhamento por tração, 230% no ensaio de tração cruzada e de 35,31 % no ensaio de fadiga quando em comparação a juntas soldadas diretamente entre as chapas de AA5754-H24 e AZ31-O.In this research was carried out a comparative study between dissimilar joints produced by means of the process FSpW without and with applying Zn as an intermediary metal with the purpose of investigating the effectiveness of the addition of this metal in the mechanical behavior of joints, as well as to assess its influence on the microstructural characteristics of the welded joints. The joints were produced with the AA5754-H24 Al alloy and the AZ31-O Mg alloy, materials of particular interest to the automotive industry. For the welding conditions with the Zn interlayer Al sheets coated by hot deep galvanizing were used. The mechanical properties of the welded joints were evaluated in terms of quasi-static and dynamic load and then correlated with the microstructural features. Through the analyzes it has been verified that the addition of Zn as an intermediary metal proved to be effective in reducing the amount of the intermetallic compound formed at the weld interface and consequently the mechanical performance increased about 48 % in the lap shear strength test, 230 % in the cross tensile strength test and 35,31 % in the fatigue test when compared to the welded joints produced by the direct contact among the AA5754-H24 and the AZ31-O sheets.
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Oliver, Abraham Johannes. "Exploring the perceptions and value of the Field Study Programme for small business owners on their human capital development." University of the Western Cape, 2016. http://hdl.handle.net/11394/5582.
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Magister Artium (Development Studies) - MA(DVS)The South African government is promoting Small, Micro- and Medium-Scale Enterprises (SMMEs) as a key strategy for job creation, economic growth for poverty alleviation and a reduction in inequalities. The sustainable development of small businesses is therefore seen as the antidote for high levels of unemployment and poverty alleviation. Academics and policy makers agree that entrepreneurs, and the new businesses they establish, play a critical role in the development and well-being of their societies. If South Africa is to overcome its pressing challenges of unemployment and poverty, it urgently needs to become a more entrepreneurial society. The Field Study Programme (FSP) initiated by the Tertiary School in Business Administration (TSiBA) in South Africa, and the Northeastern University (NU) in Boston, United States of America, aims to guide and support small business owners. The goal of the FSP was, therefore, to support small business owners to improve their understanding of managing their small business and their competency in finding innovative solutions to their current market challenges. Since the inception of the FSP at TSiBA in 2008, very little research has been undertaken to understand the value and benefits of the FSP from the perspective of community small business owners over the past seven (7) years. This study explored the perceptions and experiences of small business owners and the value of the FSP towards their small business venture to assist business schools and higher education institutions to execute FSP’s with greater success and impact. In terms of the FSP, local and international business students acted as ‘consultants’ applying their respective academic knowledge and skills to assist small business owners to adapt their business model to sustain their livelihoods. The major purpose of the FSP was for students to consult with participants regarding their needs or challenges and to transform their needs and challenges through practical intervention towards meaningful and sustainable solutions which are mutually beneficial for all parties involved. The FSP attempted to demonstrate how a joint service-learning and social entrepreneurship approach could contribute to improving the human capital of small business owners. The study applied a qualitative research approach to explore the experiences and perceptions of small business owners who participated in the FSP. Purposive sampling was used to acquire information from small business owners. In this study twenty (20), participants were chosen on the basis that they had run their own small businesses at the time of being selected for the FSP for more than 6-12 months. The FSP was conducted over a seven-month period from February 2014 to August 2014. The qualitative research instruments for this study were pre- and post-interviews with individuals and focus-group discussions. Tape recorded data was transcribed verbatim for each pre-and post-interview with individuals and focus group discussions. The researcher analysed the transcripts using thematic analysis. The study highlighted the following findings: A majority of participants reported a positive experience and satisfaction with their participation in the FSP. Most of the participants felt that the solutions presented had contributed to addressing their challenges and influenced the ongoing operations of their small business venture. It was perceived that a combined service-learning and social entrepreneurship approach to FSP could improve community outreach programs. Despite the positive feedback, more must be done to incorporate black small-businesses into the main economy. A further recommendation is that a more integrated approach is needed between small business owners and students to join forces and provide solutions and relevant skills-training once the FSP has been completed.
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Loquias, Manuel Joseph C. [Verfasser]. "Coincidences and colorings of lattices and Z-modules / Manuel Joseph C. Loquias. Fakultät für Mathematik. Forschungsschwerpunkt Mathematisierung (FSPM). Sonderforschungsbereich: Spektrale Strukturen und Topologische Methoden in der Mathematik (DFG SFB 701)." Bielefeld : Universitätsbibliothek Bielefeld, Hochschulschriften, 2011. http://d-nb.info/1015206832/34.
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Shangguan, Zhaoyun. "Understanding Food Stamp Program Participation Among Female-Headed Households: Has It Been Affected By Participation In The AFDC/TANF Program?" Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/34152.
Abstract:
The caseloads of food stamp program and welfare program experienced sharp drops among non-metropolitan single female-headed families with children (SFHFwC) after welfare reform in 1996. There is concern that leaving welfare program has led to nonparticipation in food stamp program due to multiple reasons.
This study conducts an empirical analysis of non-metropolitan SFHFwC's participation in food stamp program and welfare program, using the 1993 and 1999 CPS data. Results from using reduced-form probit model, bivariate probit model and structural probit model are compared. The reduced-form probit model considers participation in both programs as functions of all exogenous variables. The bivariate probit model allows correlation between the participation in the two programs. The structural probit model considers participation in welfare as an endogenous variable of FSP participation. Empirical analysis is also conducted through the comparison across years and between southern and the remaining U.S. states.
We found that welfare participation has a significant and positive impact on FSP participation. Households leaving welfare are more likely not to participate in FSP. Further, welfare participation is more important in determining FSP participation in 1999 than in 1993. Residence in South has a significant and negative impact in welfare participation in 1999, but has no significant impact on FSP participation in either year. Incomes and number of young children are the other major determinants of participation in both programs. Policy suggestions include improving economic situation to reduce FSP caseloads on one side, and providing more information about FSP eligibility to welfare leavers to ensure their food safety on the other side.
Master of Science
48
Da, Ros Marco Aurélio. "Estilos de pensamento em saúde pública: um estudo da produção da FSP-USP e ENSP-FIOCRUZ, entre 1948 e 1994, a partir da epistemologia de Ludwik Fleck." Florianópolis, SC, 2000. http://repositorio.ufsc.br/xmlui/handle/123456789/78913.
Abstract:
Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências da Educação.Made available in DSpace on 2012-10-17T20:47:35Z (GMT). No. of bitstreams: 0Bitstream added on 2013-07-16T18:04:32Z : No. of bitstreams: 1 170914.pdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)
DESCRIÇÃO: A presente pesquisa objetiva, a partir da epistemologia de Ludwik Fleck, caracterizar a existência de estilos de pensamento (EP) distintos e incongruentes entre si na área de saúde pública. Pretende, com esta caracterização contribuir para o entendimento dos mesmos, e em função disto, para a construção de um estilo que integre conteúdos dos anteriores em direção a um entendimento mais totalizante na área da saúde. MÉTODOLOGIA E CONTEÚDOS: A partir do universo dos resumos de teses e dissertações (858), produzidas pelas duas escolas mais importantes na área da saúde pública brasileira, entre 1948 e 1994, foram selecionadas 72 para serem analisadas e aprofundadas. Aplicando as categorias de análise de Fleck, foi construída uma metodologia para caracterizar EP. A análise das tese e dissertações foi pareada com a história: das instituições examinadas; das mudanças de compreensão do processo saúde - doença; das políticas de saúde brasileiras. O movimento simultâneo de aprofundamento da história, das categorias fleckianas, e do conteúdo dos trabalhos caracterizou a metodologia como dialética . CONCLUSÃO: Foram caracterizados 11 EPs distintos em Saúde Pública, e foi apontada a perspectiva de construção de um EP que supere os antagonismos, integrando as macro- tendências de Saúde Coletiva, Saúde Pública tradicional e Medicina Clínica. REFERÊNCIAS BIBLIOGRÁFICAS: As fontes de pesquisa incluíram, além dos 72 autores nacionais de Teses e Dissertações estudados, 61 autores nacionais e 56 autores estrangeiros.
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Blanc, Emmanuelle. "Modélisation des conséquences évolutives de la compétition pour la lumière dans des populations composites de blé." Thesis, université Paris-Saclay, 2021. http://www.theses.fr/2021UPASB013.
Abstract:
La diversité intra-spécifique, mobilisée à l'échelle de la parcelle (populations et associations variétales) devrait jouer un rôle important dans la transition agroécologique, en contribuant à l’adaptabilité et à la résilience aux stress des systèmes agricoles à bas niveaux d'intrants. Toutefois, la complexité des interactions entre plantes dans ces peuplements soulève de nombreuses questions sur leur conception et leur gestion, pour lesquelles l'approche par modélisation est particulièrement pertinente, mais peu développée à ce jour. Cette étude porte ainsi sur la modélisation structure-fonction et son utilisation pour étudier l'impact de l'architecture aérienne des plantes sur la performance et l'évolution de peuplements hétérogènes de blé. Ce projet de thèse est basé sur l'utilisation de WALTer : un modèle de plante structure-fonction préexistant qui représente le développement d'une parcelle de blé du semis à maturité et simule la plasticité du tallage (propriété de ramification) en réponse à la compétition pour la lumière. Dans un premier temps, des adaptations ont été effectuées sur WALTer pour réduire le coût computationnel des simulations, augmenter le réalisme du modèle et permettre la simulation de peuplements hétérogènes complexes. Le fonctionnement de cette nouvelle version de WALTer a ensuite été caractérisé en analysant l'impact de l'aléatoire sur les simulations et en réalisant une analyse de sensibilité sur des parcelles homogènes. D'autre part, une méthode de calibration automatique, peu développée pour ce type de modèle, a été appliquée à WALTer sur la base de données expérimentales afin d'estimer les valeurs des paramètres précédemment identifiés comme étant importants par l'analyse de sensibilité. WALTer a ensuite été utilisé pour identifier, via une analyse de sensibilité sur des mélanges binaires équilibrés, les traits de l'architecture aérienne (décrits par leurs valeurs moyennes dans le mélange et les valeurs de différences entre les 2 variétés) qui ont le plus d'impact sur la performance des mélanges. L'analyse a ainsi révélé le rôle prépondérant de la capacité de tallage et des dimensions foliaires comme déterminants de la performance des mélanges simulés. Grâce à une phase d'optimisation, les combinaisons de traits les plus favorables pour la performance des mélanges simulés ont été identifiées. Les résultats des simulations ont ainsi souligné l'importance de sélectionner soigneusement les combinaisons de traits associés en mélange, en montrant l'intérêt potentiel d'une diversité d'architecture dans les mélanges, mais également des effets défavorables possibles d'une telle diversité. Enfin, WALTer a été couplé à un modèle de génétique des populations afin de simuler l'évolution de peuplements hétérogènes de blé au cours de générations de resemis. Le couplage a été utilisé pour simuler une expérience de gestion dynamique d'une population présentant une grande diversité de hauteur. L'évolution génétique et phénotypique de la population sur 20 générations a ainsi pu être comparée à des données expérimentales pour confirmer le bon fonctionnement du couplage. Cette thèse a permis de développer des méthodes et outils pour la modélisation structure-fonction des peuplements hétérogènes de blé. Les simulations réalisées ont également apporté des éléments de compréhension sur l'impact de l'architecture aérienne sur la compétition pour la lumière dans ces peuplements. À terme, ces travaux seront utiles pour la conception et la gestion des peuplements hétérogènes de blé en champIntra-specific diversity, mobilized at the scale of the field (cultivar mixtures and composite populations) should play an important role in the agroecological transition, contributing to the adaptation and resilience of low input cropping systems, more prone to stresses. However, many questions are raised by the complex plant-to-plant interactions occurring in such heterogeneous canopies, and there is a growing need to develop modelling approaches to improve their design and management. Thus, our study focuses on the use of functional-structural plant modelling to study the impact of the aerial architecture of plants on the performance and the evolution of heterogeneous wheat populations. The thesis project is based on WALTer : a pre-existing functional-structural plant model that simulates the development of a wheat field from sowing to maturity and the plasticity of tillering (i.e. branching) in response to competition for light. In a first step, modifications were made to WALTer to reduce the computational cost of simulations, enhance its realism and improve its ability to simulate complex heterogeneous stands. The functioning of this new version of WALTer was then characterized by analysing the impact of stochasticity on the simulations and by performing a sensitivity analysis on homogeneous plots. Furthermore, on the basis of field observations, an automatic calibration method, which is rarely developed for this type of model, was applied to WALTer in order to estimate the values of the parameters previously identified as important by the sensitivity analysis. Thanks to a sensitivity analysis of balanced binary mixtures, WALTer was then used to identify the traits of the aerial architecture (described by their mean values in the mixture and the values of the differences between the 2 varieties) that have the most impact on the performance of the plots. The analysis thus revealed the preponderant role of tillering capability and dimensions of the leaves as determinants of the performance of the simulated mixtures. Thanks to an optimization phase, the combinations of traits that are the most favourable for the performance of the simulated mixtures were identified. The results of the simulations highlighted the importance of carefully selecting combinations of traits to associate in mixtures, showing the potential interest of a diversity of architecture in heterogeneous stands, but also the possible adverse effects of such diversity. Finally, WALTer was coupled to a population genetics model to simulate the evolution of heterogeneous wheat stands along generations of resowing. The coupling was used to simulate the dynamic management of a population presenting a large diversity of plant height. The genetic and phenotypic evolution of the population over 20 generations of resowing could thus be compared with experimental data to confirm the good functioning of the coupling. This thesis allowed the development of methods and tools for the functional-structural modelling of heterogeneous wheat stands. The simulations carried out have also improved our understanding of the impact of the aerial architecture on the competition for light in these stands. Ultimately, this work will be useful for the design and management of heterogeneous wheat stands adapted to farmers' needs
50
Singh, Harkanwal Nain. "A Benefit-Cost Analysis of a State Freeway Service Patrol: A Florida Case Study." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001526.