Dissertations / Theses on the topic 'Draw materials'
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Jianfeng, Wang. "Principles of the draw-bend springback." The Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1080237228.
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Wang, Jianfeng. "Principles of the draw-bend springback test." Columbus, Ohio : Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1080227128.
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Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xvii, 167 p.; also includes graphics (some col.). Includes abstract and vita. Advisor: Robert H. Wagoner, Dept. of Materials Science and Engineering. Includes bibliographical references (p. 158-167).
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Edrington, Sarah. "THE LIMITS & EFFECTS OF DRAW ON PROPERTIES AND MORPHOLOGY OF PAN-BASED PRECURSOR AND THE RESULTANT CARBON FIBERS." UKnowledge, 2017. http://uknowledge.uky.edu/me_etds/89.
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The process, structure, and property relationship of PAN fiber as a precursor to carbon fiber was studied. The limitations of stable spinning and property improvement associated with hot draw in solution spinning were found and quantified. Conditions were varied to generated precursor fiber up to the limit of draw, from which actual samples were collected for thermal conversion to carbon fiber. Samples of PAN and subsequent carbon fiber were characterized using tensile testing and x-ray analysis. The effects of draw on modulus and break stress, as well as the orientation of the crystalline structure of both parent precursor and resultant carbon fiber were found and related back to the quantified draw limit.
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Guilleaume, Christina, Alexander Brosius, and Ali Mousavi. "Investigation of Alternative Polymer Composite Materials for Forming Applications." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-235022.
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In diesem Paper werden Untersuchungen eines Tiefziehwerkzeugs aus Mineralguss vorgestellt. Der Grund für die Verwendung von Mineralguss als alternativen Werkstoff für schnelle Werkzeuge liegt in den relativ geringen Initialkosten zur Herstellung und seiner Eignung für Kleinserien und Prototypenversuche. Ähnliche Konzepte mit Werkzeugen aus Mineralguss haben gezeigt, dass eine entscheidende Grenze in der Tribologie und dem bei diesem Werkstoff großen Oberflächenverschleiß liegt. Daher fokussiert das vorliegende Paper auf die Ergebnisse der Analyse verschiedener Mineralgussmischungen unter Anwendung von Streifenzugbiegeversuchen. Die Reibzahl wurde hierbei berechnet und vergleichend einem Stahlwerkzeug gegenübergestelltThis paper presents the investigation of polymer concrete drawing tools for deep drawing operations. The goal of using polymer concrete as an alternative material is a rapid tooling process at relatively low initial tools costs that is suitable for small batch production. Similar concepts based on hydraulic concrete and polymer composites have shown that the surface tri-bology and consequently wear is the main limiting factor. Therefore, this paper focusses on the results of strip draw-bending tests with different polymer concrete mixtures. The friction coefficient is calculated and compared to a steel tool
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Garapati, Sriharsha. "Analytical and Numerical Modeling of Assembly Procedures of Steel Fulcra of Bascule Bridges." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4490.
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To model shrink-fitting in metal components, an analytical model for two long compound cylinders with temperature dependent material properties and interference between them is developed for calculating transient temperatures and stresses. A finite element model is developed for the same geometry which incorporated the temperature dependent material properties. A convergence study is performed on the finite element and analytical model. The finite element model is validated by comparing the approximations of finite element model with the analytical solution.
In an assembly procedure of fulcrums for bascule bridges, called AP1, the trunnion is shrink-fitted into a hub, followed by shrink fitting the trunnion-hub assembly into the girder of the bridge. In another assembly procedure called AP2, the hub is shrink-fitted into the girder, followed by shrink-fitting the trunnion in the hub-girder assembly. A formal design of experiments (DOE) study is conducted on both AP1 and AP2 using the finite element model to find the influence of geometrical parameters such as radial thickness of the hub, radial interference, and various shrink-fitting methods on the design parameter of overall minimum critical crack length (OMCCL) - a measure of likelihood of failure by cracking. Using the results of DOE study conducted on both the assembly procedures, AP1 and AP2 are quantitatively compared for the likelihood of fracture during assembly.
For single-staged shrink-fitting methods, for high and low hub radial thickness to hub inner diameter ratio, assembly procedure AP1 and AP2 are recommended, respectively. For fulcra with low hub radial thickness to hub inner diameter ratio and where staged shrink-fitting methods are used, for AP2, cooling the trunnion in dry-ice/alcohol and heating the girder, and for AP1, cooling the trunnion-hub assembly in dry-ice/alcohol followed by immersion in liquid nitrogen is recommended. For fulcra with high hub radial thickness to hub inner diameter ratio and where staged shrink-fitting methods are used, cooling the components in dry-ice/alcohol and heating the girder is recommended for both AP1 and AP2.
Due to the limitations of AP2, assembly procedures by heating the girder with heating coils instead of dipping an already stressed trunnion-hub assembly in liquid nitrogen are studied for decreasing the likelihood of failure by cracking and yielding. In an assembly procedure called AP3-A, only the girder is heated to shrink-fit the trunnion-hub assembly in the girder. This assembly procedure AP3-A is found to be infeasible because the girder fails by yielding if heating is expected to be completed in a reasonable amount of time. An alternative assembly procedure called AP3-B is suggested for shrink-fitting where the heating of the girder is combined with cooling the trunnion-hub assembly in dry-ice/alcohol mixture. This assembly procedure AP3-B is found to be feasible. A complete DOE study is conducted on AP3-B to find the influence of parameters like hub radial thickness and radial interference at trunnion-hub interface on the design parameter of overall minimum critical crack length. The design parameter, OMCCL values during the assembly procedure AP3-B are quantitatively compared with the widely used assembly procedures (AP1 single-stage shrink-fitting and AP1 multi-staged shrink fitting). The results of this work suggest that increasing the hub radial thickness decreases the likelihood of fracture significantly. For hubs with large radial thickness, heating the girder combined with cooling the trunnion-hub in dry-ice/alcohol mixture (AP3-B) is recommended but for hubs with low radial thickness, multistage cooling of the trunnion-hub assembly in dry-ice/alcohol mixture followed by dipping in liquid nitrogen (AP1- multistage cooling) is recommended.
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Chung, Kyu-Ha. "Composite compliant coatings for drag reduction utilizing low modulus high damping silicone rubber." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15263.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1985.MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.
Includes bibliographical references.
by Kyu-Ha Chung.
Ph.D.
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Elsayad, Kareem. "Understanding the insulating phases of disordered materials through crosstalk and Coulomb drag experiments." [Bloomington, Ind.] : Indiana University, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3290773.
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Thesis (Ph.D.)--Indiana University, Dept. of Physics, 2007.Title from dissertation home page (viewed May 28, 2008). Source: Dissertation Abstracts International, Volume: 68-11, Section: B, page: 7391. Adviser: John P. Carini.
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Grena, Benjamin (Benjamin Jean-Baptiste). "Phase separation in thermally-drawn fibers: From porous domains to structured Si-Ge spheres." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111324.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 149-160).
The preform-to-fiber thermal drawing method is a versatile process that allows the fabrication of polymer or glass-based fibers with complex multimaterial internal structures, which grant them functions ranging from optical transmission to chemical detection. However, while a wide range of materials have been successfully drawn in various phases - such as metals, semiconductors, and ferroelectric polymers - the overall structure of the fiber is typically axially-invariant and the incorporation of heterogeneous materials with isotropic microstructures such as porous domains has remained elusive thus far. In this thesis we investigate the use of in-fiber phase separation as a means to control the microstructure of different components within thermally-drawn fibers. In particular we propose a novel method based on controlled phase separation of a polymer solution that we use to embed isotropically porous polymeric domains inside multimaterial fibers. We achieve this by thermal-drawing a hollow polymer preform filled with a liquid polymer solution in its core. We later apply this method to the fabrication and characterization of scaffolds for neural regeneration. In addition, we show that the same principle can also be used to draw a functional lithium-ion fiber battery; a fiber device capable of electrochemical energy storage. Finally, we demonstrate how to produce structured Si-Ge spheres encapsulated within a silica cladding by inducing capillary breakup of a continuous Si-Ge core fiber in a strong axial thermal gradient. The thermal gradient causes a "kinetic phase separation" of the alloy, leading to structured Janus particles.
by Benjamin Grena.
Ph. D.
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Fekkai, Zakia. "Dimensional stability of biaxially drawn PET : effects of processing and material composition." Thesis, Loughborough University, 1991. https://dspace.lboro.ac.uk/2134/32890.
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Biaxial orientation of PET for the production of high strength films for demanding applications, such as slot liners for electrical motors and sound and audio visual tapes, is a well established process. More recently biaxial orientation of PET has been utilised for the production of carbonated beverages, bottles and cans for processed food packaging to achieve high strength and impact resistance. These containers, however, are not suitable for hot filling and high temperature sterilization purposes owing to the lack of dimensional stability.
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Gupta, Anurag. "The artificially blunted leading edge concept for aerothermodynamic performance enhancement." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/12442.
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Bechert, Mathias [Verfasser], Dirk W. [Gutachter] Schubert, and Benoit [Gutachter] Scheid. "Influence of Process and Material Parameters on the Draw Resonance Instability / Mathias Bechert ; Gutachter: Dirk W. Schubert, Benoit Scheid." Erlangen : FAU University Press, 2017. http://d-nb.info/114323202X/34.
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Gispert, Pellicer Esther. "El cinema com a recurs i matèria d'estudi: l'experiència de Drac Màgic." Doctoral thesis, Universitat de Girona, 1996. http://hdl.handle.net/10803/7979.
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La tesi titulada "El cinema com a recurs i matèria d'estudi: l'experiència de Drac Màgic", consta de quatre parts clarament diferenciades, però complementàries entre si, que responen a la voluntat d'orientar la introducció del cinema en l'àmbit de l'educació. L'objectiu fonamental de la primera part de la tesi és el de crear un marc teòric en el que conflueixin les recerques i les opinions de diversos autors, provinents del camp de la comunicació o bé especialistes en l'àmbit de l'educació, que s'han interrogat, des de la seva particular parcel·la d'estudi, sobre aspectes relacionats amb la presència dels mitjans de comunicació, en general, o bé sobre la incidència del cinema, en particular, en la nostra societat i en les persones. Les qüestions més bàsiques que constitueixen, segons el meu parer, els principals dubtes que ha de dissipar un educador que està interessat en la possibilitat d'introduir el cinema en la seva pràctica educativa i que són les següents: què és el cinema, per què introduir el cinema, quin cinema introduir i com introduir el cinema.La segona part de la tesi està dedicada íntegrament a l'estudi de l'experiència d'una cooperativa de Barcelona, anomenada Drac Màgic, que des de fa vint-i-cinc anys treballa en l'aplicació del cinema en l'àmbit de l'educació formal i en la formació permanent del professorat. L'anàlisi d'aquesta proposta, ens permet concretar amb un exemple pràctic, que és molt proper a la nostra realitat immediata, es aspectes teòrics que hem presentat en la primera part de la tesi. Per altra banda, l'estudi d'aquesta experiència pretén ser un punt de referència a l'hora de realitzar la proposta pràctica d'integració del cinema en els plantejaments educatius, que realitzem a la quarta part de la tesi.
En la tercera part de la tesi, hem investigat en el marc legal que configura les possibilitat i els límits que se'ls hi plantegen als professors que estan interessats en introduir els mitjans de comunicació, en general, i el cinema, en particular, en les seves pràctiques educatives. Així, doncs, per conèixer el nivell de compromís que les institucions públiques adopten per potenciar la introducció dels mitjans de comunicació en general, i del cinema, en particular, a les escoles, hem investigat en el marc legal que regula actualment el funcionament dels centres escolars i que es coneix amb el nom de Reforma educativa i també hem volgut conèixer els principals objectius i les activitats que desenvolupen dues iniciatives institucionals El Programa de Noves Tecnologies de la Informació i de la Comunicació del Ministeri d'Educació i Ciència espanyol i el Programa de Mitjans Audiovisuals del Departament d'Ensenyament de la Generalitat de Catalunya.
En la quarta part de la tesi, hem dissenyat una proposta pràctica per introduir el cinema a les escoles del nostres país, que s'ha concretat en l'elaboració d'un crèdit variable sobre cinema destinat als alumnes que cursen l'Educació Secundària Obligatòria.
The thesis entitled "The Cinema as a means and subject of study: the experience of Drac Màgic" consist of four clearly differentiated, but complementary, parts which show the intention to direct the introduction of the cinema into the area of education. The main object of the first part of the thesis is to create a theoretic framework where research and the opinion of different authors meet. These authors, from the communication field or specialists in the education field, have asked themselves, from the point of view of their specific areas of study, about aspects related to the presence of the media in general and also about the incidence of the cinema, in particular, in our society and in people. In my opinion, an educator interested in the possibility of introducing the cinema into educational practice must dispel the main doubts which are formed by the most basic questions, which are as follows: what is the cinema, why introduce it, which is to be introduced and how introduce it.
The second part of the thesis is totally dedicated to the study of the experience of a group from Barcelona called Drac Màgic, which has been working for twenty-five years on the use of cinema in the area of formal education and teacher training. The analysis of this proposal allows us to pinpoint the theoretical aspects than we have presented in the first part of the thesis with a practical example which is very close to our immediate reality. On the other hand, the study of this experience is intended to be a point of reference while at the same time carrying out the practical proposal for the integration of the cinema in the educational expositions that we make in the fourth part of the thesis.
In the third part of the thesis we have looked into the legal framework which forms the possibilities and the limits presented to the teachers who are interested in introducing the media, in general, and specially the cinema in their practical teaching. In order to know the commitment that the public institutions adopt to reinforce the introduction into schools of the media in general and specially the cinema, we have looked into the legal framework than regulates the function of schools at the present time and is know as Educational Reform (Reforma educativa) and we have also wished to know the main objectives and activities than are being developed by two institutional bodies The Programme for New Technologies of Information and Communication (Programa de Noves Tecnologies de la Informació i de la Comunicació) by the Spanish Ministry of Education and Science and the Programme of Audiovisual Media (Programa de Mitjans Audiovisuals) by the Department of Education of the Generalitat de Catalunya.
In the fourth part of the thesis we have drawn up a practical proposal on how to introduce the cinema into the schools of our country, which is to develop a variable credit about cinema for the students who are studding the Compulsory Secondary Education.
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Liu, Ning. "Microstructure and mechanical properties of cold drawn steel wires." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2012. https://ro.ecu.edu.au/theses/512.
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Cold drawn eutectoid steel wires have been widely used for a variety of applications, such as suspension bridges, steel cords for automobile tires, and springs. Much research has been done to increase their mechanical strength. With advances in modern production technology, both the drawing speed and the quality of drawn steels have been enhanced. After a careful literature survey, it is obvious that some issues are still controversial. As Y.S. Yang, J.G. Bae and C.G. Park mentioned, the lamellar spacing, thickness and volume fraction of cementites have all reached the nanometer regime, and the conventional theory is not enough to explain it. Besides, the cementite dissolution is a huge problem to the performance, according to Y.S. Yang and C.G. Park. To address the above issues, a systematic study has been taken on the wire drawing process under the conditions of the industrial production. Through the morphology, microscopic, mechanical and comprehensive analysis, a clear understanding of the microstructures and associated professing conditions of the high-strength carbon steel wires has been obtained. This project aims to clarify why the mechanical properties improve with the increasing strain. The project will be carried out in four stages: 1) characterisation of the microstructure of the cold drawn steel wires; 2) measurements of the modulus, hardness and toughness of steel wires; 3) modelling the deformation behaviour of the cold drawn steels. The techniques involved in the project include X-ray diffraction (XRD), focus ion beam (FIB), scan electron spectrum (SEM), Nanoindentation. A deep understanding of the relationship between composition, structure and performance will be achieved in this project. The results may provide the basis for improving cold-drawn steel wire designs.
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Gass, Evan M. "Anisotropy in Drawn and Annealed Copper Tube." Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou153503217197025.
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Morais, José Eduardo Vasconcelos de. "Estudo experimental e numérico de antena ressoadora dielétrica (DRA) baseada em Sr2CoNbO6." reponame:Repositório Institucional da UFC, 2014. http://www.repositorio.ufc.br/handle/riufc/10843.
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MORAIS. J. E. V. Estudo experimental e numérico de antena ressoadora dielétrica (DRA) baseada em Sr2CoNbO6. 2014. 99 f. Dissertação (Mestrado em Engenharia de Teleinformática) - Centro de Tecnologia, Universidade Federal do Ceará, Fortaleza, 2014.Submitted by Marlene Sousa (mmarlene@ufc.br) on 2015-02-27T18:05:08Z No. of bitstreams: 1 2014_dis_jevmorais.pdf: 4712454 bytes, checksum: ee61668e4d5aeb05b3eb3200bbb89387 (MD5)
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The purpose of this work was to study the dielectric properties in Radio Frequency ( RF) and microwave compound Sr 2 CoNbO 6 ( SCNO ) adding with titanium oxide ( TiO 2 ) in percentages ranging from 15 % to 22 % by mass. The SCNO is a double perovskite , which was prepared by the met hod of solid state reaction . The samples were characterized structurally by x - ray diffraction (XRD ). The method used to obtain the desired phase was by Rietveld refinement , showed that formant type cubic symmetry pm3m. The dielectric properties : dielectr ic constant ( ε ' ) and dielectric loss ( tg δ ) were measured at room temperature in the frequency range of 100 KHz to 2GHz , showed that the permittivity decreases with frequency below 50 MHz the dielectric constant is very high and above 1GHz appears low. The picnometry performed showed that the relative densities were all above 9 0 %. For the study of microwave stay full it was applied the method of Hak ki Coleman, which showed growth of the dielectric permittivity with increasing concentration of TiO 2 ( 14 - 52) a nd loss tangent ranging from 10 - 1 - 10 - 4 . The temperature coefficient of resonant frequency ( τ f) showed that SCNO τ f has a negative ( - 634ppm/oC) . With the addition of TiO 2 τ f showed positive results. The numerical simulation of the dielectric res onator antenna ( DRA ) based on SCNO and added with TiO 2 was performed with HFSS ® and the results were q uite consistent with the experiments . The low gain and a small presented to the SCNO efficiency was improved substantially with the addition of TiO 2 . These properties can be improved with a proposal for a new geometry for dielectric res o nator antenna ( D RA ) and with addition of TiO 2 in new percentages for analysis of dielectric properties and parameters of antennas
Temos como objetivo neste trabalho estudar as propriedades dielétricas em rádio frequência (RF) e micro-ondas do composto Sr2CoNbO6 (SCNO) adicionando com o óxido de titânio (TiO2) em porcentagens variando de 15% a 22% em massa. O SCNO é uma perovskita dupla, que foi preparado através do método de reação do estado sólido. As amostras foram caracterizadas estruturalmente através da difração de raio – X (DRX). O método utilizado para obtenção da fase desejada foi realizada através do refinamento de Rietveld, que mostrou estrutura de simetria cúbica do tipo pm3m. As propriedades dielétricas: constante dielétrica (ε’) e fator de perda dielétrica (tgδ) foram medidas à temperatura ambiente na faixa de frequência de 100KHz a 2GHz e mostraram que a permissividade diminui com a frequência. Abaixo de 50MHz a constante dielétrica se apresenta alta e acima de 1GHz se apresenta baixa. A picnometria realizada mostrou que as densidades relativas ficaram todas acima de 80%. Para que o estudo de micro-ondas ficasse completo aplicamos o método de Hakki Coleman, que mostrou crescimento da permissividade dielétrica com o aumento da concentração de TiO2 (14 – 52)e perdas dielétricas variando de 10-2 - 10-4 . O coeficiente de temperatura da frequência de ressonância (τf) mostrou que o SCNO apresenta τf negativo (-634ppm/oC). Com a adição do TiO2 o τf passou a apresentar valores positivos. A simulação numérica de uma antena ressoadora dielétrica (DRA) baseada no SCNO e adicionada com TiO2 foi realizada através do software HFSS® e os resultados se apresentaram bastante concordantes com os experimentos. O baixo ganho e uma pequena eficiência apresentada para o SCNO puro foi melhorado substancialmente com a adição do TiO2. Estas propriedades podem ser melhoradas com uma proposta de uma nova geometria para a (DRA) e com adição do TiO2 em novas porcentagens para análises de propriedades dielétricas e parâmetros de antenas.
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Jörgensdotter, Freja. "Bli en miljönär med klimatsmarta drag i vardagen : En informationsbroschyr med fokus på miljö, konsumtion och material." Thesis, Linnéuniversitetet, Institutionen för design (DE), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-63782.
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Abstrakt Under 2015 behandlades 4 703 790 ton hushållsavfall på Sveriges återvinningscentraler, det motsvarar 477 kilo per person/år. Ofta kastar vi fullt fungerande saker. När det gäller livsmedel så kastar vi utan att ens lukta eller smaka, många gånger före det att bäst-före-datum har gått ut. Utan att vi reflekterar över miljökonsekvenserna köper vi produkter i dubbla förpackningar, plaster, folier och pappersförpackningar, utan att de extra emballagen egentligen fyller någon större funktion. Vi kör flera vändor till återvinningscentraler med vårt trädgårdsavfall och tidningarna åker rakt i soporna. Det är varken miljömässigt- eller ekonomiskt hållbart. Jag vill få oss att reflektera och tänka till en gång extra. Hur kan jag förändra mina köpvanor och konsumtionsmönster på ett enkelt och smidigt sätt, som fungerar i vardagen och inte krånglar till det? Genom att ge ut en informationsbroschyr, innehållande enkla tips och råd hur vi ska agera medvetna konsumenter, hoppas jag kunna bidra till att vi alla blir våra egna miljönärer så att hushållsavfallet kan minska. Projektet "Bli en miljönär med klimatsmarta drag i vardagen" är ett samarbete med miljöbolaget VMAB, Västblekinge Miljö AB. VMAB är ett av alla miljöbolag i Sverige som samordnar kommunernas avfallshantering och som även svarar för behandling av avfall. I samverkan med VMAB har jag tagit fram en informationsbroschyr med fokus på miljö, konsumtion och material för att öka kunskapen kring avfallsslag, hur de hanteras och på vilket sätt avfallet kan återvinnas eller återanvändas.
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Kalagotla, Dilip. "Modeling Particle Drag in Accelerating Flows with Implications for SBLI in PIV - A Numerical Analysis." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1523630352322552.
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Kumbier, Alana. "Ephemeral Material: Developing a Critical Archival Practice." Columbus, Ohio : Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1236198205.
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Freese, Samuel Henrique. "Estudo da capacidade de proteção anti-corrosiva de óleos de processo em materiais trefilados." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/75758.
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Aços carbono trefilados possuem como características excelentes propriedades mecânicas, estabilidade dimensional e bom acabamento superficial. Porém, para fornecimento deste material, um dos cuidados necessários é a proteção temporária contra a corrosão atmosférica, que pode ser definida como um processo resultante de reações químicas e/ou eletroquímicas, pelas quais metais e ligas se deterioram quando submetidos à ação climática. Para evitar / retardar este processo, usualmente é utilizada a aplicação de uma película de óleos formadores de barreira, protegendo o material base. Buscando avaliar a capacidade protetiva de óleos utilizados em materiais trefilados, foram selecionados 3 tipos de produtos usados no polimento e 3 tipos aplicados como proteção final. Diferentes combinações dos produtos foram avaliadas em amostras numa câmara úmida, mostrando que a capacidade protetiva dos óleos de proteção final está diretamente relacionada à sua densidade, diferentemente dos óleos de polimento que não apresentam uma relação direta com as propriedades avaliadas. Com base nestes resultados, pode-se prever a capacidade protetiva de óleos de proteção final utilizando sua densidade como referência, devido a esta relação ser linear, tendo outros fatores, como o tipo de óleo de polimento, afetando a constante da equação da curva.Drawn carbon steel has excellent mechanical proprieties, dimensional stability and good surface quality as characteristics. But, to supply this material, a necessary care is the temporary protection against atmospheric corrosion, which can be defined as a process resulting from chemical and / or electrochemical reactions, in which metals and alloys deteriorate when subjected to climate action. To avoid / retard this process, usually it’s used an application of an oil coat that protects the base material. Trying to understand the protective capacity of oils used in drawn materials, 3 products used in polishing process and 3 applied as final protection were selected. Samples tested in humid chamber with different combinations of products were evaluated, showing that the protective capacity of oils used as final protection is directly related with their density, a relation that is not presented in polishing oils. With these results we can forecast the protective capacity of oils used as final protection employing its density as reference, because of the linear relation, having another factors, like the type of polishing oil, affecting the curve equation constant.
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Rubenking, Samuel Kim. "Dual Mode Macro Fiber Composite-Actuated Morphing Tip Feathers for Controlling Small Unmanned Aircraft." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78433.
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The transition of flight from manned to unmanned systems has led to new research and applications of technology within the field that, until recently, were previously thought to be unfeasible. The industry has become interested in alternative control surfaces and uses for smart materials. A Macro Fiber Composite (MFC), a smart material, takes advantage of the piezoelectric effect and provides an attractive alternative actuator to servos in the Small Unmanned Aerial Systems (SUAS) regime of flight. This research looks to take MFC actuated control surfaces one step further by pulling inspiration from and avian flight. A dual mode control surface, created by applying two sets of two MFCs to patch of carbon fiber, can mimic the tip feathers of a bird. This actuator was modeled both using Finite Element Analysis (FEA) and Computational Fluid Dynamics (CFD). Real-world static testing on a feather confirmed preliminary FEA results, and wind tunnel tests simulating assumed cruise conditions confirmed the feather would not exhibit any adverse structural behaviors, such as flutter or aeroelastic divergence. From its modeled performance on a wing using CFD, the MFC feather proved to be a success. It was able to produce a wing that, when compared to a traditional rectangular wing, yielded 73% less induced drag and generated proverse yaw. However, the MFC feathers alone, in the configuration tested, did not produce enough roll authority to feasibly control an aircraft.Master of Science
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Ma, Ning. "Theory and modeling of microstructural evolution in polycrystalline materials solute segregation, grain growth and phase transformation /." Connect to this title online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1111774761.
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Thesis (Ph. D.)--Ohio State University, 2005.Title from first page of PDF file. Document formatted into pages; contains xvii, 181 p.; also includes graphics (some col.). Includes bibliographical references (p. 168-181). Available online via OhioLINK's ETD Center
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Soroudi, Azadeh. "Melt Spun Electro-Conductive Polymer Composite Fibers." Doctoral thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-3590.
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One interesting approach is the development of conductive polymer composite fibers for innovative textile applications such as in sensors, actuators and electrostatic discharge. In this study, conductive polymer composite fibers were prepared using several different blends containing conductive components: a conjugated polymer (polyaniline-complex) and/or carbon nanotubes. Different factors such as processing parameters, the morphology of the initial blends and the final fibers, fiber draw ratio and material selection were studied separately to characterize their effects on the fiber properties. In binary blends of PP/polyaniline-complex, the processing conditions, the matrix viscosity and the fiber draw ratio had substantial effects on the electrical conductivity of the fibers and linearity of resistance-voltage dependence. These factors were associated with each other to create conductive pathways through maintaining an appropriate balance of fibril formation and breakage along the fiber. The blend morphology was defined as the initial size of the dispersed conductive phase (polyaniline-phase), which depended on the melt blending conditions as well as the PP matrix viscosity. Depending on the initial droplet phase size, an optimum draw ratio was necessary to obtain maximum conductivity by promoting fibril formation (sufficient stress) and preventing fibril breakage (no excess stress) to create continuous pathways of conductive phase. Ternary blend fibers of PP/PA6/polyaniline-complex illustrated at least three-phase morphology with matrix/core-shell dispersed phase style. When ternary fibers were compared to binary fibers, the former could combine better mechanical and electrical properties only at a specific draw ratio; this showed that draw ratio was a more determinant factor for the ternary fibers, as both conductivity and tensile strength depended on the formation of fibrils from the core-shell droplets of the PA6/polyaniline-complex through the polypropylene matrix. The achieved maximum conductivity so far was in the range of 10 S/cm to 10 S/cm, which for different samples were observed at different fiber draw ratios depending on the mixing conditions, the matrix viscosity or whether the fiber was a binary or ternary blend. To improve the properties, PP/polyaniline-complex blends were filled with CNTs. The CNTs and the polyaniline-complex both had an increasing effect on the crystallization temperature and the thermal stability of PP. Furthermore, the maximum conductivity was observed in samples containing both CNTs and polyaniline-complex rather than the PP with either one of the fillers. Although increasing the content of CNTs improved the conductivity in PP/CNT fibers, the ease of melt spinning, diameter uniformity and mechanical properties of fibers were adversely affected. Diameter variation of PP/CNT as-spun fibers was shown to be an indication of hidden melt-drawings that had occurred during the fiber extrusion; this could lead to variations in morphology such as increases in the insulating microcracks and the distance between the conductive agglomerates in the drawn parts of the fiber. Variations in morphology result in variations in the electrical conductivity; consequently, the conductivity of such inhomogeneous fiber is no longer its physical property, as this varies with varying size.Thesis to be defended in public on Friday, May 20, 2011 at 10.00 at KC-salen, Kemigården 4, Göteborg, for the degree of Doctor of Philosophy.
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Narvaez, Javier Artemio. "Evaluation of Alumina Nanofluids and Surfactant Drag Reducing Solutions to Improve Heat Transfer for Aircraft Cooling Systems." University of Dayton / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=dayton154479500350447.
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Egunov, Aleksandr. "Strain-engineering of thin polymer films : a novel route for the development of functional materials and microfluidic devices." Thesis, Mulhouse, 2015. http://www.theses.fr/2015MULH1619.
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Les deux systèmes de création d’une contrainte dans les films polymériques ont été développés, chacun répondant à un gradient de gonflement du polymère dans la direction normale au film. Ce gonflement peut être provoqué soit par la présence d’un gradient de densité de réticulation dans la direction normale à la surface (films de poly(4-vinylpyridine) réticulés par UV ou dans les films de chitosan réticulés thermiquement et ioniquement ; ou soit par une pénétration asymétrique de vapeur de solvant dans le film (ici le polydiméthylsiloxane oxydé en surface). Un troisième système polymérique auto-enroulant a également été réalisé par la création d’une contrainte permanente au sein du film de polydiméthylsiloxane, grâce à l’extraction sélective d’un additif non-réticulé, l’huile de silicone. Un modèle théorique du processus d’auto-enroulement, basé sur la théorie linéaire d’élasticité a ainsi pu être proposéTwo systems of stress creation in the polymer films were developed, each based on the swelling gradient in the direction normal to the film. This swelling may be caused either by the presence of a crosslinking density gradient in the direction normal to the surface (poly (4-vinylpyridine film) crosslinked by UV or in the thermally or ionically crosslinked chitosan films; or by asymmetric penetration of solvent vapor in the film (here polydimethylsiloxane surface-oxidized). A third self-rolling polymeric system has also been realized by the creation of a permanent strain in the polydimethylsiloxane film by selective extraction of a non-cross-linked additive, silicone oil. A theoretical model of self-rolling process based on the linear theory of elasticity has been proposed
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Laffargue, Johann. "Etude et modélisation des instabilités du procédé de soufflage de gaine." Phd thesis, École Nationale Supérieure des Mines de Paris, 2003. http://pastel.archives-ouvertes.fr/pastel-00000432.
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Strandlund, Henrik. "Simulation of diffusional processes in alloys : techniques and applications." Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-399.
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Sung, Ji-Hyun. "The Causes of “Shear Fracture” of Dual-Phase Steels." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1268039436.
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Bindas, Erica Bindas. "EFFECT OF TEMPERATURE, STRAIN RATE, AND AXIAL STRAIN ON DIRECT POWDER FORGED ALUMINUM-SILICON CARBIDE METAL MATRIX COMPOSITES." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1530871866585058.
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Machala, Petr. "Návrh potrubního řetězového dopravníku." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-416427.
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This master thesis deals with the construction design of two different pipeline drag chain conveyors for transport of wheat and sewage sludge. The first part describes the operation principle and the main parts of this conveyor. The examples of designs from several manufacturers follow. Next part is devoted to determining the resistance to movement in individual sections of the transport route. Thesis continues with design proposals of both variants of conveyors, including suitable technological and strength calculations. The outputs of this work are also assembly drawings of these two conveyors.
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Abbasi, Baharanchi Ahmadreza. "Development of a Two-Fluid Drag Law for Clustered Particles Using Direct Numerical Simulation and Validation through Experiments." FIU Digital Commons, 2015. http://digitalcommons.fiu.edu/etd/2489.
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This dissertation focused on development and utilization of numerical and experimental approaches to improve the CFD modeling of fluidization flow of cohesive micron size particles. The specific objectives of this research were: (1) Developing a cluster prediction mechanism applicable to Two-Fluid Modeling (TFM) of gas-solid systems (2) Developing more accurate drag models for Two-Fluid Modeling (TFM) of gas-solid fluidization flow with the presence of cohesive interparticle forces (3) using the developed model to explore the improvement of accuracy of TFM in simulation of fluidization flow of cohesive powders (4) Understanding the causes and influential factor which led to improvements and quantification of improvements (5) Gathering data from a fast fluidization flow and use these data for benchmark validations. Simulation results with two developed cluster-aware drag models showed that cluster prediction could effectively influence the results in both the first and second cluster-aware models. It was proven that improvement of accuracy of TFM modeling using three versions of the first hybrid model was significant and the best improvements were obtained by using the smallest values of the switch parameter which led to capturing the smallest chances of cluster prediction. In the case of the second hybrid model, dependence of critical model parameter on only Reynolds number led to the fact that improvement of accuracy was significant only in dense section of the fluidized bed. This finding may suggest that a more sophisticated particle resolved DNS model, which can span wide range of solid volume fraction, can be used in the formulation of the cluster-aware drag model. The results of experiment suing high speed imaging indicated the presence of particle clusters in the fluidization flow of FCC inside the riser of FIU-CFB facility. In addition, pressure data was successfully captured along the fluidization column of the facility and used as benchmark validation data for the second hybrid model developed in the present dissertation. It was shown the second hybrid model could predict the pressure data in the dense section of the fluidization column with better accuracy.
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Tevissen, Etienne. "Méthodologie d'étude et modélisation du transport de solutes en milieux poreux naturels : application à la migration du chrome dans la nappe alluviale du Drac (Isère)." Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL089N.
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On présente une méthodologie d'étude du transport de solutés interactifs en milieu poreux naturel, basée sur l'expérimentation et la modélisation. La modélisation s'effectue grâce à un code de calcul couplant hydrodynamique et géochimie, des améliorations y sont apportées avec la prise en compte de corrections d'activité et surtout, avec la simulation d'effets cinétiques chimiques ou diffusionnels. La méthodologie proposée a été appliquée au cas de migration du chrome dans la nappe alluviale du Drac (Isère). L'étude du site expérimental associée à la connaissance générale de la chimie du chrome, a permis de définir et de cadrer les expériences à mener au laboratoire pour caractériser les interactions du chrome avec les alluvions. Ces expériences ont montré que c'est un phénomène d'adsorption qui impose la répartition du chrome hexavalent entre phases mobile et immobile. Ce phénomène a ensuite été décrit à l'équilibre thermodynamique par deux modèles, le premier utilise un phénomène élémentaire de type échange anionique entre chromate et bicarbonate, le second est résumé à une loi de Langmuir. Les courbes expérimentales ont été simulées en considérant ces deux modèles avec des limitations cinétiques. Les expériences de traçage sur le site ont montre que le chrome hexavalent y a un comportement equivalent a un traceur d'eau. Ce résultat souligne que certains paramètres capacitifs des interactions ne peuvent être déterminés au laboratoire et doivent faire l'objet de mesures in-situ
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Withrow, Travis P. "Computational Modeling of Atom Probe Tomography." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1525763934302517.
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Zuanetti, Bryan. "Plate Impact Experiments for Studying the Dynamic Response of Commercial-Purity Aluminum at Temperatures Approaching Melt." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1557132337419911.
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Asp, Grönhagen Klara. "Phase-field modeling of surface-energy driven processes." Doctoral thesis, KTH, Metallografi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11036.
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Surface energy plays a major role in many phenomena that are important in technological and industrial processes, for example in wetting, grain growth and sintering. In this thesis, such surface-energy driven processes are studied by means of the phase-field method. The phase-field method is often used to model mesoscale microstructural evolution in materials. It is a diffuse interface method, i.e., it considers the surface or phase boundary between two bulk phases to have a non-zero width with a gradual variation in physical properties such as energy density, composition and crystalline structure. Neck formation and coarsening are two important diffusion-controlled features in solid-state sintering and are studied using our multiphase phase-field method. Inclusion of Navier-Stokes equation with surface-tension forces and convective phase-field equations into the model, enables simulation of reactive wetting and liquid-phase sintering. Analysis of a spreading liquid on a surface is investigated and is shown to follow the dynamics of a known hydrodynamic theory. Analysis of important capillary phenomena with wetting and motion of two particles connected by a liquid bridge are studied in view of important parameters such as contact angles and volume ratios between the liquid and solid particles. The interaction between solute atoms and migrating grain boundaries affects the rate of recrystallization and grain growth. The phenomena is studied using a phase-field method with a concentration dependent double-well potential over the phase boundary. We will show that with a simple phase-field model it is possible to model the dynamics of grain-boundary segregation to a stationary boundary as well as solute drag on a moving boundary. Another important issue in phase-field modeling has been to develop an effective coupling of the phase-field and CALPHAD methods. Such coulping makes use of CALPHAD's thermodynamic information with Gibbs energy function in the phase-field method. With the appropriate thermodynamic and kinetic information from CALPHAD databases, the phase-field method can predict mictrostructural evolution in multicomponent multiphase alloys. A phase-field model coupled with a TQ-interface available from Thermo-Calc is developed to study spinodal decomposition in FeCr, FeCrNi and TiC-ZrC alloys.QC 20100622
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Bessa, Kleiber Lima de. "Redução de arrasto por adição de polímeros em escoamento pulsátil laminar e turbulento em leitos arteriais caudais de ratos normotensos e hipertensos e tubos rígidos." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3150/tde-12092008-140246/.
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Nesse trabalho, foi analisada a redução de arrasto, a partir da utilização de duas bancadas experimentais, onde uma delas está situada no laboratório de Mecânica dos Fluidos (EPUSP) e a outra, no laboratório de Fisiologia Vascular (ICB-USP). A redução de arrasto foi investigada a partir do uso dos seguintes polímeros: poliacrilamida 1822S e 1340S, polietileno glicol (PEG4000) e óxido de polietileno (Polyox WSR-301). O comportamento reológico das soluções poliméricas do PEG4000 e das poliacrilamidas foi adquirido experimentalmente, enquanto do Polyox WSR-301 foi obtido da literatura. Esses polímeros foram utilizados na bancada experimental da EPUSP, simulador hidrodinâmico, mas somente o PEG4000 foi utilizado na bancada experimental do ICBI em leitos arteriais caudais de ratos normotensos (Wistar) e espontaneamente hipertensos (SHR). No simulador hidrodinâmico, foi estudada a redução de arrasto em escoamentos pulsáteis laminares e turbulentos, cuja faixa de Reynolds varia entre 2300 a 13700, com concentrações poliméricas que variaram entre 5 e 100 ppm, porém para o PEG4000 essa concentração atingiu valor de 5000 ppm. Em leitos arteriais caudais de ratos, a redução de arrasto foi analisada para escoamento laminar, cuja faixa de Reynolds varia entre 100 e 700, com concentração polimérica de 5000 ppm. Além disso, a redução de arrasto foi estudada na presença e ausência das células endoteliais. Simulações computacionais utilizando o método dos volumes finitos (Fluent) foram realizadas a partir dos dados obtidos da bancada experimental do ICB-I, para avaliar a distribuição da tensão de cisalhamento sobre a parede do vaso na presença e ausência das células endoteliais e do PEG4000, considerando a parede da artéria rígida. A partir dos dados obtidos da análise da viscosidade, ficou constatado que o PEG4000 com concentração de 5000 ppm e as poliacrilamidas 1822S e 1340S com concentrações de 5 e 10 ppm apresentaram comportamento de fluido Newtoniano. Para as poliacrilamidas, concentrações poliméricas acima de 10 ppm apresentaram comportamento de fluido não-Newtoniano. De acordo com a literatura, o Polyox WSR-301 apresentou comportamento de fluido Newtoniano para todas as concentrações poliméricas utilizadas nesse trabalho. O PEG4000 não apresentou o fenômeno da redução de arrasto em nenhuma concentração polimérica analisada, quando aplicado na bancada experimental da EPUSP. As poliacrilamidas e o Polyox WSR-301 apresentaram reduções de arrasto que foram dependentes do número de Reynolds e da concentração utilizada, muito embora o Polyox WSR-301 tenha se mostrado mais eficiente em promover esse fenômeno. Nos leitos arteriais caudais, o PEG4000 apresentou redução de arrasto para a concentração de 5000 ppm, que foi acentuada pela presença das células endoteliais. Os valores da tensão de cisalhamento foram maiores para o animal SHR quando comparados com o animal Wistar. Além disso, no animal Wistar, o endotélio controlou o aumento dessa tensão via produção de substâncias vasodilatadoras, mas apresentou disfunção no animal SHR. A partir dos resultados apresentados acima, podese concluir que o Polyox WSR-301 é mais eficiente para promover a redução de arrasto em tubos rígidos. Por outro lado, muito embora o PEG4000 não tenha apresentado efeito na bancada experimental da EPUSP, esse se mostrou um bom redutor de arrasto em leitos arteriais caudais, tendo sua ação intensificada pela presença das células endoteliais.In this work, the drag reduction was analyzed in two benches located at Laboratory of Fluid Mechanics at Polytechnic School (EPUSP) and at Laboratory of Vascular Physiology at Institute of Biomedical Science (ICB-USP). The drag reduction was investigated for the following polymers: polyacrilamide 1822S and 1340S, polyethylene glycol (PEG4000) and polyethylene oxide (Polyox WSR-301). The rheological behavior of polymeric solutions of polyacrilamide and PEG4000 was acquired experimentally; while it was obtained from the literature for Polyox WSR-301. All of these polymers were used in the hydrodynamic simulator, but only PEG4000 was employed in the tails arterial bed from normotensive (Wistar) and spontaneously hypertensive rats (SHR) at ICB-1. In the hydrodynamic simulator, the drag reduction was analyzed in laminar and turbulent pulsatile flow, in the range varying between 2300 and 13700, with polymeric concentrations between 5 and 100 ppm, but for PEG4000, concentration has reached 5000 ppm. On the other hand, in the tail arterial beds, the drag reduction was analyzed for laminar flow, in the range between 100 and 700, with polymeric concentration of 5000 ppm. In addition, it was studied in the presence and absence of endothelial cells. Computational simulation using the finite volume method (Fluent) was performed using data obtained from ICB-1 in order to analyze the wall shear stress distribution along of wall vessel both in the presence and absence of endothelial cells and PEG4000, considering the rigid walls. Polyacrilamide 1822S and 1340S as well as PEG4000 showed behavior of Newtonian fluid in the following concentrations: 5 and 10 ppm and 5000 ppm, respectively. On the other hand, for polyacrilamides, concentrations higher than 10 ppm showed behaviour of non- Newtonian fluids. According to the literature, the Polyox WSR-301 behaved as a Newtonian fluid in all concentrations used in this work. At EPUSP\'s bench, while PEG4000 did not show drag reduction for any polymeric concentration analyzed, this phenomenon could be seen for polyacrilamides and Polyox WSR-301, being dependent on Reynolds number as well as polymeric concentration. More important, Polyox WSR- 301 showed to be the most efficient drag reducer of them. Interestingly, in the assays employing the tail arterial beds, PEG4000 showed drag reduction in the concentration of 5000 ppm and it was increased by the presence of the endothelial cells. Thus, Polyox WSR-301 seems to be more efficient to promote drag reduction in the rigid tubes. On the other hand, while PEG4000 did not show drag reduction at EPUSP\'s bench, it was a good drag reducer in the tail arterial beds, being intensified by the action of endothelial cells.
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Marou, Alzouma Ousseini. "Durabilité tribologique de matériaux pour insert de dents de tunnelier." Thesis, Ecully, Ecole centrale de Lyon, 2015. http://www.theses.fr/2015ECDL0042.
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La fréquence des opérations de maintenance lors de l’excavation du sol par les tunneliers est problématique pour les entreprises de travaux publics. Ces opérations de maintenance engendrent des temps morts onéreux et nécessitent l'intervention d'opérateurs dans des conditions de travail hyperbares. Une des raisons aux nombreuses interventions humaines pour la maintenance est l’endommagement des outils racleurs du sol excavé (dents) qui sont placés sur la tête du tunnelier. Ces outils sont sujets à l’usure compte tenu de l’abrasivité des différents milieux qu’ils rencontrent. Le but de cette thèse est de contribuer à augmenter d’au moins 20% la durée de vie des matériaux constitutifs de ces outils, afin de réduire les différentes opérations de maintenance qui exposent les opérateurs à des risques importants. Pour atteindre cet objectif, les investigations menées dans ce travail ont porté sur plusieurs axes. Dans un premier temps, une expertise est menée pour identifier les modes d’endommagement prédominants sur les inserts à base de carbure de tungstène placés sur les dents ; ensuite, de nouveaux matériaux avec des propriétés mécaniques et des microstructures optimisées, développés dans le cadre du projet européen NeTTUN, sont caractérisés sur des bancs d’essais représentatifs. Ces essais ont permis de bien comprendre les mécanismes d’usure des nouveaux matériaux à base de carbure de tungstène. Les résultats de ce travail peuvent ensuite donner lieu à de nouvelles orientations en matière de choix de matériaux pour renforcer les dents de tunnelierThe frequency of maintenance operations during the excavation of the ground by the tunnel boring machines (TBM) is problematic for civil engineering companies. These maintenance operations provoke expensive timeouts and they bring in excavation operators in risky hyperbaric work conditions. One of the reasons which leads to the numerous human interventions for the maintenance is the damage of drag bits located on the cutting wheel of the TBM. These drag bits undergo wear due to the abrasiveness of the various media they meet. The purpose of this thesis is to contribute to increase by 20 % at least the lifetime of the materials of the dag bits, in order to reduce the various maintenance operations which expose the operators to important risks. To achieve this goal, the investigations led in this work concerned several axes. At first, an expertise is led to identify the wear modes prevailing on the carbide inserts located on the drag bits; then, new materials with enhanced mechanical properties and optimized microstructures, developed in the framework of the European project NeTTUN, are characterized on representative lab testing devices. These tests allowed us to understand well the wear mechanisms of the newly developed grades of tungsten carbides. The results of this work can lead to new strategies for the selection of materials to reinforce the drag bits
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Vieluf, Maik. "Hochauflösende Rutherford-Streuspektrometrie zur Untersuchung von ZrO2-Schichtwachstum im Anfangsstadium." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-38113.
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Die vorliegende Arbeit entstand im Rahmen einer Kooperation des Forschungszentrums Dresden-Rossendorf mit Qimonda Dresden GmbH & Co. OHG. Mithilfe der hochauflösenden Rutherford-Streuspektrometrie (HR-RBS) wurden das Diffusionsverhalten und Schichtwachstum von ZrO2 auf SiO2 und TiN im Anfangsstadium untersucht. Auf Grund der exzellenten Tiefenauflösung von 0,3 nm an der Oberfläche stand die Analyse von Konzentrationsprofilen in ultradünnen Schichten, respektive an deren Grenzflächen im Vordergrund. Zur qualitativen Verbesserung der Messergebnisse wurde erstmals ein zweidimensionaler positionsempfindlicher Halbleiterdetektor in den Aufbau der HR-RBS implementiert und charakterisiert. Außerdem wurde ein Messverfahren in Betrieb genommen, das mögliche Schädigungen durch den Ioneneintrag in die Messprobe minimiert. Durch die Optimierung der experimentellen Bedingungen und die Entwicklung eines Programmpaketes zur Unterstützung des Analysten konnte ein effizienter Routine-Messablauf erstellt werden. Im Moment einer binären Kollision zwischen einfallendem Ion und Targetelement kommt es bei kleinem Stoßparameter zu Veränderungen des Ladungszustands der gestreuten Ionen, insbesondere durch die abrupte Geschwindigkeitsänderung des Projektils und der Überlappung der Elektronenwolken. Bei der HR-RBS mit Energie separierendem Dipolmagneten muss zur Interpretation von Streuspektren die Ladungszustandsverteilung der gestreuten Projektile bekannt sein. Erstmalig konnte eine signifikante Abhängigkeit der Ladungszustandsverteilung gestreuter C-Ionen sowohl von der Schichtdicke als auch der Ordnungszahl des detektierten Targetelements, hier der vierten Nebengruppe, nachgewiesen werden. Diese gewonnen Erkenntnisse ermöglichten systematische Untersuchungen zum ZrO2-Schichtwachstum im Anfangsstadium. Zur Herstellung der ZrO2-Schichten wurde die Atomlagenabscheidung (ALD) verwendet. Anhand der nachgewiesenen Agglomeration von ZrO2 auf nativen SiO2 wurde mithilfe der Rasterkraftmikroskopie (AFM) zur Bestimmung von Oberflächenrauigkeiten eine Methode konzipiert, welche die Auswirkung lokaler Schichtdickeninhomogenitäten auf die niederenergetische Flanke eines Streuspektrums berücksichtigt. Auf dieser Grundlage durchgeführte Simulationsrechnungen ergeben, dass keine Diffusion von Zr in die darunter liegende Schicht stattfand, jedoch eine ZrSiO4-Grenzflächenschicht existiert. Für das Wachstum von ZrO2 auf TiN wird aus den hoch aufgelösten Streuspektren ein völlig anderes Verhalten abgeleitet. Messungen zu Oberflächentopografien der TiN-Schicht liefern nicht zu vernachlässigende Werte für die Rauigkeit. Um den Einfluss der Oberflächenrauigkeit auf die Form des hoch aufgelösten Spektrums erfassen zu können, wurde eine Software entwickelt. Auf Basis von AFM-Messungen ermöglicht dieses Programm das Extrahieren einer Energieverteilung aus den Weglängen von ausschließlich an der Oberfläche gestreuten Ionen. Unter Berücksichtigung des Effekts der Oberflächenrauigkeit auf die HR-RBS Spektrenform konnte die Diffusion von Zr in das polykristalline TiN erstmals verifiziert werden. Die Beobachtungen weisen daraufhin, dass bereits nach dem ersten ALD-Zyklus ein geringer Anteil der deponierten Zr-Atome bis in eine Tiefe von etwa 3 nm in das TiN diffundiert. Die vorläufigen Ergebnisse legen Korngrenzendiffusion naheThis thesis originated from a cooperation between Research Center Dresden-Rossendorf and Qimonda Dresden GmbH & Co. OHG. By means of High Resolution Rutherford Backscattering Spectrometry (HR-RBS) the diffusion behaviour and layer growth of ZrO2 on SiO2 and TiN in the initial regime were investigated. The analysis of concentration profiles in ultrathin layers and interfaces was the focus of this work, made possible by the excellent depth resolution of less than 0.3 nm near the surface. For the first time a two-dimensional position sensitive semiconductor detector was implemented and characterized in the setup of the HR-RBS for the improvement of the quality of the measurement results. Furthermore, a measurement procedure was put into operation that allowed the reduction of ion induced damage. Through the optimization of the experimental conditions and the development of a program package for the support of the analyst, an efficient measurement procedure could be routinely ensured. At the time of a binary collision between the incident ion and the target element with a small impact factor, the charge state changes frequently, especially due to the abruptly decreasing ion velocity of the projectile and the overlapping of the electron clouds. For HR-RBS with an energy-separating dipole magnet, the charge state distribution of the scattered ions must be known for the interpretation of the measured spectra. For the first time a significant dependence of the charge state distribution of the scattered C ions on the layer thickness as well as atomic number of the detected target elements, here from the fourth subgroup, was emonstrated. This new knowledge allowed systematic investigations of the ZrO2 layer growth in the initial regime. The ZrO2 layers were produced by means of the atomic layer deposition (ALD). Based on the evidence for agglomeration of ZrO2 on SiO2 a method was introduced, which takes local thickness variations into account during the simulation of the HR-RBS spectra. An accurate statement about the ZrO2/SiO2 interface was possible due to the extraction of the thickness variation by the atomic force microscopy (AFM). The boundary surface is sharp except for a small intermediate ZrSiO4 layer and no diffusion of Zr atoms in SiO2 could be detected. A quite different behaviour could be derived from high resolution spectra for the growth of ZrO2 on TiN. Measurements of the surface topography of the TiN layer revealed non negligible values for the surface roughness. A program was developed to capture the influence of the surface roughness on the shape of the high resolution spectrum. This software uses AFM measurements to extract an energy distribution from calculated path length differences for ions scattered at the sample surface. Diffusion of Zr into polycrystalline TiN was demonstrated for the first time taking into account the effect of the surface roughness on the shape of the spectra. This observation indicates that already after the first ALD reaction cycle a small part of the deposited Zr atoms diffuses into the TiN layer up to a depth of 3 nm. Such preliminary results suggest grain boundary diffusion
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Rabiee, Hesamoddin. "Gas responsive microgels as novel draw agents for forward osmosis desalination." Thesis, 2018. http://hdl.handle.net/2440/114507.
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Forward Osmosis (FO) process is a low-energy membrane separation technique, which has attracted increasing attention recently for desalination applications. Unlike Reverse Osmosis, which needs a high-pressure pump; FO works via natural osmotic pressure provided by a draw solution. Therefore, development of efficient draw solutions is quite important. Polymeric stimuli-responsive microgels/hydrogels are promising options as they can be recovered by applying the proper stimulus heating or gassing processes. The temperature-responsive microgels/hydrogels have been developed for FO application in recent years. This thesis study was aimed to the development of gas-responsive microgels as draw solutions for FO desalination. Two main series of microgels: CO₂-responsive and O₂-responsive microgels are for the first time fabricated and evaluated for FO desalination throughout the thesis. The feed saline water used here is 2000 ppm NaCl, which is considered as brackish water. A few of polymer monomers with tertiary amine moieties are selected for synthesizing CO₂-responsive microgels. Water flux of the microgels was measured by monitoring conductivity of the saline feed water and interpreting it to the water flux through the membrane. The microgels are active and protonated as a draw solution after CO₂ purging, and can be recovered after CO₂ stripping by N₂ purging. Microgels synthesised with diethylaminoethyl methacrylate (DEAEMA) can provide water flux as high as 56 LMH. Characterization tests are carried out to explore the most-effective microgels with respect to cationic monomers: DEAEMA and dimethylamino ethyl methacrylate (DMAEMA), and the type and concentration of crosslinkers: poly (ethylene glycol diacrylate) (PEGDA), N,N′-methylene-bisacrylamide (BIS) and ethylene glycol dimethacrylate (EGDMA). The microgels are recovered at their isoelectric point, where microgels are not charged and release water easily. O₂-responsive microgels are synthesised and their FO desalination performance is studied systematically. Two Fluoro-containing monomers (2,3,4,5,6 pentafluorostyrene (FS), 2,2,2-trifluoroethyl methacrylate (FM)), which are responsive to oxygen, are selected to copolymerize with four suitable ionic and non-ionic monomers: DEAEMA, Hydroxyethyl methacrylate (HEMA), DMAEMA and N-isopropylacrylamide (NIPAM). The results show that the water recovery ratio can be enhanced if a proper non-ionic monomer like NIPAM is used. The O₂-responsive microgels synthesised by DMAEMA and 5wt% FM monomer can perform the highest water flux up to 29 LMH. The experimental data reveal that HEMA is not a suitable non-ionic monomer to synthesise O₂-responsive microgels as HEMA has –OH groups, which lead to high negative surface charges and affect the water recovery. FO desalination data show that O₂-responsive microgels perform comparable water flux and water recovery capability. Dynamic light scattering (DLS) as the main characterization test for microgels is done. The microgels show larger hydrodynamic diameter after CO₂ or O₂ purging and they become smaller after removing these gases via N₂ purging. The swelling ratio for the microgels is up to 14 and 6.5 for CO₂ responsive and O₂-responsive microgels, respectively. As new polymer draw agents, CO₂- and O₂-responsive microgels demonstrate high water flux and water recovery capabilities as promising draw solutes for energy-effective FO desalination. CO₂-responsive DEAEMA microgels with 1wt% PEGDA crosslinker performed water flux of 56 LMH with 50 % water recovery ratio. DMAEMA CO₂-responsive microgels perform smaller water flux due to lower pKₐ of DMAEMA than DEAEMA. O₂-responsive microgels show relatively lower water flux than CO₂-responsive microgels. The best water flux performance is observed for DEAEMA/DMAEMA-5wt% FM microgels with 26-29 LMH, while the highest water recovery is given by NIPAM-5wt% FM microgels with 56%.Thesis (M.Phil.) (Research by Publication) -- University of Adelaide, School of Chemical Engineering, 2018.
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"Forward Osmosis Desalination Using Thermoresponsive Hydrogels as Draw Agents; An Experimental Study." Master's thesis, 2019. http://hdl.handle.net/2286/R.I.53871.
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abstract: Hydrogel polymers have been the subject of many studies, due to their fascinating ability to alternate between being hydrophilic and hydrophobic, upon the application of appropriate stimuli. In particular, thermo-responsive hydrogels such as N-Isopropylacrylamide (NIPAM), which possess a unique lower critical solution temperature (LCST) of 32°C, have been leveraged for membrane-based processes such as using NIPAM as a draw agent for forward osmosis (FO) desalination. The low LCST temperature of NIPAM ensures that fresh water can be recovered, at a modest energy cost as compared to other thermally based desalination processes which require water recovery at higher temperatures. This work studies by experimentation, key process parameters involved in desalination by FO using NIPAM and a copolymer of NIPAM and Sodium Acrylate (NIPAM-SA). It encompasses synthesis of the hydrogels, development of experiments to effectively characterize synthesized products, and the measuring of FO performance for the individual hydrogels. FO performance was measured using single layers of NIPAM and NIPAM-SA respectively. The values of permeation flux obtained were compared to relevant published literature and it was found to be within reasonable range. Furthermore, a conceptual design for future large-scale implementation of this technology is proposed. It is proposed that perhaps more effort should focus on physical processes that have the ability to increase the low permeation flux of hydrogel driven FO desalination systems, rather than development of novel classes of hydrogelsDissertation/Thesis
Masters Thesis Mechanical Engineering 2019
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Yu, Da-Wei David. "Turbulent pipe flow drag reduction with narrow distribution polystyrene materials : a test of drag reduction theories." Thesis, 1998. http://hdl.handle.net/1957/34137.
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Mowery, Daniel Michael. "Investigation of the structure of cold -drawn high -density polyethylene using solid-state NMR." 2002. https://scholarworks.umass.edu/dissertations/AAI3068580.
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In this dissertation, the cold-drawing response of a commercial high-density polyethylene (HDPE) resin has been studied using solid-state nuclear magnetic resonance (NMR) spectroscopy and variety of other complementary techniques. Melt-crystallized, isotropic samples of the HDPE have been drawn to various extensions at ambient temperature (21°C) and at a relatively slow strain rate (0.0013 s−1). Using solid-state NMR, the first unambiguous evidence for a major morphological component intermediate to the crystalline and amorphous domains in the cold-drawn HDPE microstructure has been found. Employing an ‘inverse 13 C T1 filter’ and other filtering techniques, signals from the various components have been selected and compared. The intermediate component comprises chains of all-trans conformation but with significant disorder in packing. The chains show fast, intermediate-amplitude motions about their axes and are generally aligned with the draw direction, but with a greater distribution of orientation angles relative to crystalline phase. A quantitative 13C NMR procedure has been utilized in the analysis of morphological component composition during cold drawing. In the undeformed material, the NMR-derived composition shows excellent agreement with other common techniques. The mass fraction of the intermediate component has been measured by NMR to be as high as 35% in the cold-drawn HDPE, greater than the contributions from the amorphous domains and monoclinic crystals. The intermediate component content dramatically increases by 240% just after necking, along with a doubling in the monoclinic crystals. At the same time, decreases of about 25% in the total crystalline and amorphous phases occur. A general re-ordering in the microstructure takes place during neck propagation and strain hardening. The total crystallinity rises by about 8%, with a corresponding decrease in the monoclinic crystals (50%) and amorphous material (30%). Based on 1H spin diffusion data, a microstructural model of cold-drawn HDPE is offered. The spin diffusion data identify the intermediate component with tie-molecule bundles that connect small ‘mosaic block’ crystallites (ca. 10–15 nm side dimension) along the draw direction. The bundles consist of about 30 chains and are estimated to be about 2.5 nm in diameter and 3 nm in length.
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"Understanding the insulating phases of disordered materials through crosstalk and Coulomb drag experiments." INDIANA UNIVERSITY, 2008. http://pqdtopen.proquest.com/#viewpdf?dispub=3290773.
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Hoppe, Richard Peter. "Partial characterization of extruded collagen tubes with varied material deposition and orientation based on rotation rate and linear draw speed." Thesis, 2001. http://library1.njit.edu/etd/fromwebvoyage.cfm?id=njit-etd2001-019.
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Liang, Ting-Hua, and 梁庭華. "A Study of High Dielectric Constant Material TiO2 Deposited by Electron Beam Evaporation for DRAM Capacitors." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/04098952902900584893.
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碩士國立交通大學
電子研究所
84
In this work, the effects of electrode materials (W, WN, Ta, TaN, Mo, and TiN)on the leakage current of TiO2 films were studied. The optimum electrode materials for high- and low- temperature processes (800 ℃ and 400 ℃) are shown. No obvious correlation between ψms and Vcrit (voltage at 10E-6 A/ cm2)is found in our experimental results. We also discussed post-TiO2-deposition annealing effect using TaN top electrode. The effects of annealing ambient, annealing temperature, and annealing time are included. In annealing ambient effect, temperature dependence of leakage current was investigated. On the other hand, the effects of TiO2 film thickness and doping concentration of boron-doped substrate were analyzed. We have then demonstrated that rapid thermal N2O (RTN2O) annealing is the most effective method in suppressing leakage current of TiO2 films, compared with furnace O2 (FO) and rapid thermal O2 (RTO) annealing. For future studies, optimal process conditions of RTN2O annealing are required to further improve performance of TiO2 capacitors.
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Tasi, M. S., and 蔡明憲. "A Study of High Dielectric Constant Material Barium Strontium Titanite (BaxSr1-xTiO3) for Giga Bit DRAM Stroage Capacitor Applications." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/52288061739048398386.
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碩士國立交通大學
電子研究所
84
As device dimensions are scaled down into the deep-submicron regime, the demand for small capacitor area while still maintaining a certain critical charge for DRAM capacitors become more stringent. Ta2O5 films are suitable for 256M to 1G bit DRAM application. However, higher dielectric constant materials are required for 1 Gbit DRAMs and beyond. Recently the BST (BaxSr1-xTiO3) film has attracted great attentions due to its high dielectric constant, low leakage current, TDDB over 10 years, resistance to process induced damage, good chemical and thermal stability and low dissipation factor. In this study, we present the physical and electrical properties of BST films deposited by RF magnetron sputtering. The effect of deposition temperature, the sputtering oxygen partial pressure and film thickness on the physical properties (grain size, orientation) electrical (leakage current, breakdown voltage, polarization, dielectric conatant) properties were investigated in details. In addition, a post-deposition thermal treatment by furnace annealing in N2 ambient was used to improve the electrical characteristics.
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lin, mark, and 林俊賢. "A Study of Advanced DRAM Capacitor Structure with Rugged Poly-Si Electrode and High Dielectric Constant Material & Process Optimization for Improved Retention Characteristic." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/62652947292432198404.
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博士國立交通大學
電子工程系
88
Abstract The main goal of this thesis is to improve the refresh time of DRAM cell. It can be accomplished by two approaches. The first approach is to increase the storage capacitance of the cell, while the other approach is to reduce the junction leakage current of DRAM cell. For increased storage capacitance, polycrystalline silicon film with a rugged surface (i.e., rugged poly-Si) was applied. The rugged-poly was deposited by a single-wafer rapid thermal chemical vapor deposition (RTCVD) system, suitable for 12-inch wafer fabrication. In this thesis, the rugged poly-Si films have been successfully fabricated to serve as the bottom storage electrode for the stacked capacitor in dynamic random access memory cells. Our study suggests that the rugged poly-Si is actually formed by the nucleation generation on the amorphous silicon surface and subsequent crystalline growth during the annealing step following deposition. An effective surface area of approximately 2.9 times that of a conventional poly-Si film electrode is obtained. In addition, we have fabricated and studied the electrical and physical characteristics of Ta2O5 films on rapid thermal nitrided (RTN) rugged polycrystalline silicon electrodes for 256M dynamic random access memory (DRAM) application. To overcome the higher leakage current on Ta2O5 films with rugged poly-Si bottom electrodes, we have successfully employed a light oxidation on rugged poly-Si grains for improving the acute angle of surface morphology, and a post-treatment with rapid thermal nitridation of N2O on Ta2O5 films to reduce the leakage current. The successful integration of Ta2O5 film with rugged poly-Si makes it very promising for future 256M dynamic random access memory (DRAM) application. Since the retention time distribution of DRAM consists of a ‘tail distribution’ and a ‘main distribution’. Increasing the storage capacitance only improves the ‘main distribution’ of the DRAM array, but it does not change the tail distribution. Since the refresh characteristics of a DRAM array are determined by the worst-case bits represented by the ‘tail distribution’, so increasing the storage capacitance does not improve the overall refresh characteristics of the DRAM array. The ‘tail distribution’ is found to be affected by thermionic field emission (TFE) current of dislocation and stacking faults, while the ‘main distribution’ is affected by generation-recombination (G-R) current of SiO2/Si interface trapped center and H-atom trapped center. We have performed a detailed study, and found that the ‘tail distribution’ is affected by HDP, furnace oxidation, and etching profile processes. In contrast, we found that the ‘main distribution’ is strongly affected by H2 plasma treatment, and HDP trench filling processes. In this thesis, we have also performed a detailed study on how to optimize shallow trench isolation for DRAM application. The retention time distribution is improved in new DRAM generation by the new STI isolation process. However, the degree of improvement is retarded if furnace linear oxide linear is used. The control of defect generation is therefore very important to improve the retention time distribution. Finally, the effects of contact resistance of the refresh characteristics of DRAM cell were studied. Silicidation process is optimized in order to obtain low contact resistance. We found that the contact resistance of the sample with TiN capping layer is lowered by 10-15% and the nature good yield (minimum refresh time of DRAM up to 80 ms) is higher by 19.7% than those of the sample without TiN capping layer,.