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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
271

Vliv mazacích kapalin na průvodní veličiny tváření závitů / On the effect of lubricating fluids on specific phenomena of thread forming

Vnuková, Zuzana January 2021 (has links)
The main task of this work was to compare the being used process fluids in mechanical engineering with a focus on polymer and additive fluids. Selected polymer and nanoadditive fluids were compared based on a thread forming test, during which different concentrations of individual fluids were tested. All data from experiments were evaluated, assessed in terms of their properties, and recommended for further practice.
272

Výroba součásti plošným tvářením / Production single parts from sheet metal

Hartelová, Karolína January 2008 (has links)
The elaborate project present suggestion of technology of produktion pressed piece from engineering steel 11 375 in framework of engineering studies in branch 2307. Production series do 100 000 pieces. By virtue of literary study of surface forming work and calculation was devised procedural tool. The tool is solved by form usual rack fix on crank press LEN 40 (producer TOMA Industries Trnava), with traction 400 kN. Punch and stamping die are made from tool steel 19 436.3 (POLDI 2002) along graphic documentation.
273

Výroba kotevního prvku / Manufacturing of wall clamp

Isakidis, Petr January 2011 (has links)
The design which was work out in college plan M2I-K is setting up a production technology for an wall clamp from a steel plate 11 321.1. Based on the literature search it was chosen optimal technology of cutting and forming. Structural and technological calculations were implemented for these methods and the composite machine tool was projected. The eccentric bending press CDCH 3000P was chosen because of its working power. Working parts of the tool are made from steel 19 436.3. Price of the component is 36 Czech crowns which is result
274

Výroba spojovacího čepu objemovým tvářením / Bulk forming technology of connecting pin

Trnka, Filip January 2013 (has links)
The project elaborated in frame of engineering studies branch M-STG proposes a technology of connecting pin – structural steel 11 320 5R. The technological calculations were performed and the production procedure was devised on the basic on the literary study of cold bulk forming with concentration on the extrusion and upsetting. Forming machine was design HATEBUR BKA-3 with a nominal power 1800 kN. The component is made in four forming operations. Extruder will be made from tool steel 19 830, extrusion die from tool steel 19 830 and clamp ring from tool steel 19 740.
275

Technologie výroby titanového výfuku / Technology of manufacturing of titan exhaust

Hrubý, Patrik January 2015 (has links)
The Diploma Thesis deals with the technology of manufacturing the titan exhaust for a two-stroke engine. It includes a description of the manufacturing procedure. It analyzes in detail the forming issue of sheet-metal parts in order to eliminate the spring-back effect, and it finds possible solutions to this problem.
276

Behaviour and design of direct-formed hollow structural section members

Tayyebi, Kamran 06 July 2021 (has links)
In North America, cold-formed square and rectangular hollow sections (collectively referred to as RHS hereinafter) of commonly specified cross-sectional dimensions are produced using either the indirect-forming approach or the direct-forming approach. The indirect-forming approach, as the conventional approach of the two, consists of three steps: (i) roll-forming the coil material progressively into a circular hollow section; (ii) closing the section using electric resistance welding (ERW); and (iii) reshaping the circular section into the final square or rectangular shape. On the other hand, the direct-forming approach, as the new approach of the two, roll-forms the coil material directly into the final square or rectangular shape. RHS with similar cross-sectional dimensions but different production histories (i.e., different cold-forming approaches and post-production treatments) are expected to have significantly different material and residual stress properties. However, RHS design provisions in the existing North American steel design standards (AISC 360-16 and CSA S16-19) are in general developed based on research on indirect-formed RHS and currently do not differentiate RHS cold-formed by different approaches. Based on the research presented in Chapter 1 of this thesis, comparing to indirect-formed RHS, direct-formed RHS in general contain lower levels of residual stresses around cross sections, since the flat faces are not severely cold worked during production. This in turn affects member behaviours under compressive and flexural loadings. The test results presented in Chapters 2 and 4 show that direct-formed RHS have superior stub column and beam behaviours, comparing to their indirect-formed counterparts. In particular, the stub column and beam testing programs, covering a wide range of cross-section dimensions and two strength grades (nominal yield stresses of 350 and 690 MPa), show that the slenderness limits in the existing North American steel design standards are excessively conservative for direct-formed RHS, resulting in unnecessary penalty and member strength underestimation. As a result, the existing design formulae are not suitable for direct-formed RHS. In response to this, subsequent finite element (FE) parametric investigations are performed and presented in Chapters 3 and 5. Modified stub column and beam design recommendations for direct-formed regular- and high-strength RHS are proposed. The effects of post-cold-forming hot-dip galvanizing on material properties, residual stresses, stub column behaviours and beam behaviours of direct-formed regular- and high-strength RHS are also studied in Chapters 1-5 of this thesis. Similar to the application of the heat treatment per ASTM A1085 Supplement S1 or the Class H finish per CSA G40.20/G40.21, post-cold-forming galvanizing improves the stub column (Chapter 2) and beam (Chapter 4) behaviours of direct-formed RHS via effective reduction of residual stresses (Chapter 1). Based on subsequent FE parametric investigations, modified stub column and beam design recommendations catering to galvanized direct-formed RHS are proposed in Chapters 3 and 5. / Graduate
277

HÉMO-IONIC®,un nouvel hémostatique actif sur la réparation tissulaire : de l'hémostase à la phase de maturation / HÉMO-IONIC®, a new hemostatic active in tissue repair : from hemostasis to maturation phase

Ponsen, Anne-Charlotte 11 January 2019 (has links)
Suite à une lésion, la réparation d’un tissu à l’identique est l’objectif clinique recherché. Ainsi un hémostatique, au-delà de sa capacité à arrêter un saignement, se doit au minimum de ne pas être délétère pour la réparation tissulaire. Or, malgré une efficacité hémostatique démontrée Tachosil® et Surgicel®, couramment utilisés en chirurgie, peuvent générer en raison de leur persistance in situ associée à une résorption incomplète, des évènements indésirables graves (nécrose, hypersensibilité, allergie, sténose, complication thromboembolique, sepsis…). Dans ce contexte, nous avons étudié les effets d’un nouvel hémostatique non implantable, HÉMO-IONIC®, sur toutes les étapes de la réparation tissulaire : de l’hémostase à la phase de maturation. HÉMO-IONIC®, Tachosil® et Surgicel® ont été évalués in vitro sur la fonctionnalité des Endothelial Colony Forming Cells (ECFCs) ; et in vivo dans deux modèles murins, un modèle d’hémostase et un de réparation tissulaire. Grâce à ces travaux, constituant une approche originale de l’évaluation des hémostatiques, nous avons démontré que seul HÉMO-IONIC®, en plus d’être un hémostatique efficace, maintient l’ensemble des propriétés fonctionnelles des cellules endothéliales et agit, à plus long terme, positivement sur l’ensemble des étapes de la réparation tissulaire. Ces données ouvrent des perspectives particulièrement intéressantes, notamment dans la prise en charge des brûlures nécessitant la restitution d’un tissu cutané de qualité (souple et élastique). Ainsi, l’association d’HÉMO-IONIC® à l’expertise du Service de Santé des Armées (SSA) dans l’utilisation des cellules stromales mésenchymateuses comme Médicament de Thérapie Innovante (MTI) pourrait représenter, dans la prise en charge des brûlures, une avancée thérapeutique en améliorant les résultats fonctionnels et esthétiques. / After an injury, the clinical objective is to faithfully repair tissues. Thus, a hemostatic agent, beyond its ability to stop bleeding, must at least not be deleterious for tissue repair. However, despite proven hemostatic efficacy, Tachosil® and Surgicel®, which are commonly used in surgery, can lead to serious adverse events (necrosis, hypersensitivity, allergy, stenosis, thromboembolic complication, sepsis…) due to their in situ persistence associated with their incomplete resorption. In this context, we studied the effects of a new non-implantable hemostatic agent, HÉMO-IONIC®, on all stages of tissue repair : from hemostasis to maturation phase. The effects of HÉMO-IONIC®, Tachosil® and Surgicel® were assessed in vitro on Endothelial Colony Forming Cell function (ECFCs) and in vivo in two mouse models of hemostasis and tissue repair. Using an original approach to the assessment of hemostatic agents, we showed that only HÉMO-IONIC®, in addition to being effective, maintained all the functional properties of endothelial cells and acted positively on all stages of tissue repair in the longer term. These data open up very interesting perspectives, in particular in the management of burns where restoring a quality cutaneous tissue (supple and elastic) is required. Thus, in burn management, combining HÉMO-IONIC® with the French Defence Health service expertise in the use of mesenchymatous stromal cells as an advanced therapy medicinal product could be a therapeutic advance by improving the functional and esthetic outcomes.
278

Characterization of Mitilysin Pores by Cryo-electron Microscopy

Novakovic, Vladimir January 2023 (has links)
Pore forming toxins (PFTs) are a large group of proteins found mainly in bacteria with some exceptions found in animals. They bind and form pores in their target membranes and form pores, which leads to cell death. Among these are cholesterol-dependent cytolysins (CDC), which require the presence of cholesterol to bind target membranes. Mitilysin (Mly), a protein of interest in this project, belongs to the CDC group of pore forming toxins. It is produced by the bacterium Streptococcus mitis, a pathogen closely related to Streptococcus pneumoniae, found in human oral cavity, which causes several diseases such as Viridans Group Streptococcal (VGS) toxic shock syndrome and endocarditis. Mly is a homologue of the toxin Pneumolysin, which is produced by S. pneumoniae. However, the mechanism of pore formation is not well known. The purpose of this project is to understand the mechanism of CDC pore formation, focusing on the key amino acid residues that are responsible for transitioning from Mly pre-pore to pore state. The findings will aid in the design of inhibitors of pore formation as potential anti-bacterial drug candidates. The major goal of the project was to determine the 3-dimensional (3D) structure of assembled Mly pore. Mly is expressed in E.coli and purified by Ni-NTA affinity chromatography. Pore formation is confirmed by a hemolysis assay and negative stain-transmission electron microscopy. Mly pores are vitrified, analyzed and imaged in a cryo-electron microscope. 2D images were processed to generate a 3D density map. However, our Mly pore 3D map was incomplete due to lack of 2D projection angles resulting from preferred orientation of pore particles during sample preparation. To overcome this problem, we aim to use DNA origami, which requires His-tagged Mly. We were able to determine that His-tagged Mly retains its pore formation ability.
279

Liturgievorming in 'n veranderende konteks

Bester, Hendrik Gideon 06 1900 (has links)
The forming of liturgy in the Dutch Reformed Church is in a crisis. The current context demands new liturgies in order to facilitate meaningful communication between God and His children. The problem is that no healthy practice of liturgy forming exists and more decay than change takes place. Therefore, the need exists for a workable theory for liturgy forming which can be used in the forming of a justified liturgy. In this study a theory and liturgies are worked out which takes the liturgy forming through the centuries into account. The theory, which is known as the three resources theory, is a dynamic theory in which the energy resources are placed in interaction with one another in order to form new liturgies. The three energy resources are the Bible, the tradition and the context. These three resources are focused on an eschatological focus point in the future. The Bible as energy resource especially has authority since it contains the worship style and example of Jesus Christ. The tradition exists of the narrative off liturgy forming through the centuries. The tradition offers a treasure of examples, which can be used for liturgy forming in the current context. The current context forms an integral part of the liturgy forming process. The post-modernism, the remains of the modernism, globalisation, the transformation process in South Africa and the modem developments in the human sciences are all forces which influence the liturgy forming process indirectly. These energy circles are placed in interaction with one another, new justified liturgies are formed which makes meaningful communication between God and His children possible. The investigation on liturgy forming in 13 various congregations in England and South Africa indicated that, where one or more of the energy resources is neglected, responsible energy forming does not take place. The current context requires that modem liturgy should emphasize symbols, emotion and dialogue. More love should also be shown during services. / Die liturgievorming van die Ned Geref Kerk is in 'n krisis. Die huidige konteks stel nuwe eise aan die liturgie wat vra vir nuwe liturgiee om die kommunikasie tussen God en Sy kinders sinvol en betekenisvol te fasiliteer. Die probleem is dat daar nie 'n gesonde praktyk van liturgievorming bestaan nie en dat meer verval as verandering plaasvind. Daar is dus 'n behoefte aan 'n werkbare teorie vir liturgievorming wat gebruik kan word in die vorming van verantwoorde liturgie. In hierdie studie word 'n teorie en liturgiee uitgewerk wat die werkende energiebronne in liturgievorming deur die eeue in ag neem. Die teorie, wat bekendstaan as die driebronneteorie, is 'n dinamiese teorie waarin die energiebronne in wisselwerking met mekaar geplaas word vir die vorming van nuwe liturgiee. Die drie energiebronne is die Skrif, die tradisie en die konteks. Hierdie drie bronne word gefokus op 'n eskatologiese fokuspunt in die toekoms. Die Skrif as energiebron is veral gesagdraend omdat dit die aanbiddingstyl en voorbeeld van Jesus Christus bevat. Die tradisie bestaan uit die verhaal van die liturgievorming deur die eeue waar die drie energiebronne telkens in wisselwerking met mekaar was. Die tradisie bied 'n skatkis van voorbeelde waaruit geleen kan word vir liturgievorming in die huidige konteks. Die huidige konteks is 'n integrale deel van die liturgievormingsproses. Die Postmodemisme, die reste van die Modemisme, globalisering, die oorgangsituasie in Suid-Afrika en hedendaagse ontwikkelinge in die menswetenskappe is almal kragte wat indirek inwerk op die liturgievormingsproses. Slegs wanneer die energiesirkels in wisselwerking met mekaar geplaas word, word verantwoordelik nuwe liturgiee gevorm wat sinvolle kommunikasie tussen God en sy kinders bewerkstellig. Die ondersoek na die liturgievorming in 12 verskillende gemeentes in Engeland en Suid-Afrika het aan die lig gebring dat waar een of meer van die energiebronne verwaarloos word, verantwoordelike vorming nie plaasvind nie. Die huidige konteks vra dat byderwetse liturgie meer klem op simbole, emosie en dialogiese kommunikasie sal plaas. Liturgie sal ook moeite moet doen om meer liefde oor te dra in die eredienste. Ter wille van die fasilitering van 'n dieper spiritualiteit kan die liturgie van die Ned Geref Kerk spesifieke liturgiese elemente en -houdings gaan leen by antler spiritualiteite en so sy eie liturgie verbreed. Dit bly 'n haalbare uitdaging om voortdurend verantwoordelik liturgie te vorm indien die Skrif, die tradisie en die konteks as energiebronne in wisselwerking met mekaar geraadpleeg word en gefokus word op die eskatologiese. / D.Th. (Practical Theology)
280

Desenvolvimento de aços para conformação a frio de elemento de fixação do feixe de molas / Development of steel for cold forming of U-Bolts for leaf springs

Ventura, Jaime Milan 29 September 2006 (has links)
Neste trabalho foi desenvolvido o material e o processo de fabricação, que possibilitasse a fabricação de grampo de feixes de mola para veículos comerciais leves, médios e pesados, sem a necessidade de aplicação de tratamentos térmicos como têmpera e revenido. Assim, foram desenvolvidos/analisados cinco tipos de aço com adição de cromo, níquel e silício que possibilitassem a conformação a frio do grampo, garantindo as propriedades mecânicas requeridas pelos grampos, tais como: resistência à tração (900 MPa mín.), limite de escoamento (720 MPa mín.), alongamento(10% min.) e dureza(24-32 HRC). Os aços desenvolvidos exibiram uma microestrutura composta de grãos de perlita e ferrita, sendo que o tamanho de grão perlítico (ASTM) entre 9 a 11 foi obtido pela adição dos elementos de liga alumínio e vanádio que atuaram como refinadores de grão. A avaliação das propriedades mecânicas foram realizadas segundo a norma ASTM A-370 e os corpos de prova foram ensaiados em um sistema dinâmico MTS 810. As análises microestruturais dos aços, após a deformação a frio, foram realizadas por meio de microscopia ótica e eletrônica de varredura, com o objetivo de se identificar a deformação a frio nas áreas desejadas. A validação final do aço e do processo de fabricação do produto foi obtida após a conclusão do ensaio de fadiga que foi realizado em temperatura ambiente, sob carregamento cíclico tração-tração com R = 0,1 e freqüência de 30 Hz, onde a metodologia Probabilidade acumulada da falha (Weibull) foi utilizada para auxiliar na conclusão final do projeto. Foi observado que o aço tipo-4 com adição de cromo (0,21%) apresentou o melhor resultado em fadiga. / In this present work the steel and the production process was developed, in order to produce U-Bolts to light, medium and heavy commercial vehicles, without any heat treatment, such as heating and tempering. Thus, this search of five types of steel with chrome, nickel and silicium addictions for the U-Bolts cold forming, assuring the mechanical properties required, as, strength (900 MPa min), yield stress (720 MPa min), elongation (10% min) and hardness (24-32 HRC). The developed steel exhibited a microstructure composed by perlite and ferrite, with the perlite grain size (ASTM) from 9 to 11, as aluminum and vanadium acted as grain size refiners. The evaluation of the mechanical properties was made according to ASTM A-370 and the samples tested in a dynamic system MTS 810. The microstructure analyses of the steel after cold forming were made using optical and scanning eletronic microscopic, in order to identify the cold forming process. For the steel and the production process validation a techniques fatigue test. They were carried out under a load-controlled (tensile-tensile), R = 0,1 and 30 Hz frequency, using the Weibull statistic method, to the final conclusion of he project. Type-4 steel with chrome addiction (0,21%) presented the best result in the fatigue test.

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