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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.
51

Montovaná konstrukce výrobního komplexu s administrativou / Precast construction of production complex with administration

Škoda, Martin January 2017 (has links)
This Final thesis deals with the desig of main supporting structure of the precast concrete frame. Calculation of internal forces is made by sofrware system Dlubal RFEM. For the assessment were selected two most loaded beams with corresponding columns and calyx on the pilot. This thesis contains structural design, mounting report, sectional calsulations of selected elements, mounting details, workshop documentation of selected elements.
52

Entwicklung eines Befestigungssystems für Photovoltaikmodule

Tautenhahn, Lutz 30 January 2015 (has links)
Der derzeitige technische Fortschritt stützt sich maßgeblich auf die Nutzung von elektrischem Strom. Der Anteil der Stromerzeugung aus Sonnenlicht hat mittlerweile in Deutschland den der Wasserkraft überschritten, der 1990 noch der größte regenerative Energielieferant war. Die Technologie der Photovoltaik (PV) wandelt die hochenergetische Strahlung der Sonne in elektrischen Strom um und nutzt dabei häufig Glasplatten als tragende Struktur. Der Hauptanspruch dieser Arbeit liegt in der Entwicklung und Untersuchung eines Befestigungssystems mit einer höher- oder hochmoduligen Klebverbindung zum gläsernen PV-Modul sowie einer möglichst universell einsetzbaren Fügeverbindung zur Unterkonstrukion. Die systematische Enwicklung der Fügeverbindung zum PV-Modul basiert auf dem Ansatz eines flexiblen, stützenden \\hbox{Ringes} für das Fügeelement (Halter), um die durch eine mechanische Belastung der Module induzierten Zugspannungen im Glas über der Fügeelementkante zu reduzieren. Eine neuartige, kombinierte Klammer-Keil-Verbindung sichert die Befestigung auf einer von ihr unabhängigen Unterkonstruktion sowohl quer als auch längs zur Schienenrichtung. Experimentelle Arbeiten charakterisieren die eingesetzte Klebverbindung unter verschiedenen Beanspruchungsszenarien, um sowohl konstruktions- als auch klebstoffbedingte Möglichkeiten und Grenzen der Fügeverbindung für die vorliegende Anwendung zu identifizieren. Die Untersuchungen weisen zudem geeignete Vorbehandlungsmaßnahmen der Aluminiumoberflächen aus. Sowohl numerische Simulationen als auch die neuartig eingesetzte Nahbereichsphotogrammetrie bestätigen in Bauteiluntersuchungen die vorteilige Wirkung des flexiblen, höhermodulig geklebten Ringes. Die vorliegende Arbeit setzt sich hierbei auch kritisch mit unterschiedlichen Einflüssen auf die Ergebnisse auseinander, die einerseits durch verschiedene Prüfstände hervorgerufen werden können und andererseits auch den verwendeten Methoden zugrunde liegen. / Today much of technical advances are due to the usage of electricity. The contribution of solar power to the production of electricity in Germany currently surpasses water powered electricity which was in 1990 the almost exclusive renewable energy source. The technology of photovoltaic systems based on high-powered sun radiation, often utilizes glass plates as a supporting structure. This dissertation primarily focuses on the research and development of a mounting system with a higher or high modulus adhesively bonded joint to the PV-module as well as an all-purpose connection to the substructure. The systematical development process of the connection to the PV-module is based on the approach of a flexible supporting ring-shaped mounting element. This reduces the tension within the glass surface at the edge of the mounting element when mechanically loading the PV-module. A novel connection using a clamp-wedge combination ensures the ability to mount the PV-module horizontally or vertically to the rail substructure. Through the development process, the bonded joint is exposed to various scenarios where the construction as well as the adhesive possibilities and limitations under each scenario are analyzed. Research outcomes yield recommendations for appropriate pre-treatment of the aluminum surfaces. Numerical simulations as well as the novel use of the near-field photogrammetry method confirmed beneficial action of the flexible ring-shaped mounting element within assembly testing of large glass specimens. This dissertation discusses how different variables can have a considerable effect on results when introduced through the testing device and through monitoring methods.
53

Piezoelectric actuation of an aero engine fuel metering valve

Bertin, Michael January 2017 (has links)
Servo valves are used in a broad variety of flow modulation applications. In the field of aerospace, servo valves are used in aero engines to meter fuel flow. The existing valves are labour intensive to manufacture and highly optimised such that to achieve improvements in performance requires a novel design. This research investigates smart material actuators and valve concepts. Specifically, a prototype pilot stage nozzle flapper valve is developed for the purpose of actuating a main stage spool. The typical nozzle flapper type servo valve uses a torque motor to actuate the flapper. In this research project, the torque motor has been substituted for two piezoelectric ring bender actuators. A novel mounting mechanism has been developed to secure the ring benders within the valve. Analytical and finite element models have been made to understand the displacement mechanism of a ring bender and the effects of the mount on the displacement and force from a ring bender, and the results were compared with experiment. The mounting stiffness at the inner and outer edges was found to decrease the displacement of the ring bender and it was found that the stiffness of the mount at the outer edge has a greater negative effect on displacement than the stiffness of the mount at the inner edge. The displacement of a ring bender was tested across the operational temperature range of an aero engine. It was found that the displacement of the ring bender is reduced at low temperatures and increases at high temperature. The variation of stiffness of the elastomeric mount was also tested with temperature and it was found that the displacement of a ring bender is significantly reduced when the mounting elastomer approaches its glass transition temperature. A prototype valve was built to test the pressures and flows that could be achieved at two control ports by using a ring bender as actuator. A single ring bender and two ring benders, mounted in tandem to provide redundancy, have been tested. An analytical model was developed and the predictions are compared with experimental results for pressures and flow. The full stroke of the valve was 300m when mounted and reduced to 150m when mounted in tandem with an inactive ring bender. The hysteresis of the valve is +/-10%. The pressures and flow at and between the control ports of the valve are consistent with the predictions.
54

Design av mikrovågsövergångar / Design of microwave connections

Petersson, Björn January 2003 (has links)
<p>In this Master thesis, microwave connections between circuit boards are constructed. The primary frequency band is the X-band (8-12 GHz). The purpose of the connections is to enable a more simple and cheaper way of mounting the circuit boards inside a container. </p><p>The connections have been designed and evaluated, using different computer programs. A few prototypes have been built and measured. </p><p>The main goal of this Master thesis was to design a connection, that would be useful in practice. The connections should be easy to manufacture and have a good performance. They should also have a high tolerance for manufacturing errors. </p><p>The main part of this report contains descriptions of different designs. The designs are presented together with simulated and measured results. </p><p>The report contains designs based upon coplanar waveguides and a phase shifting technique. The result shows that designs that are using coplanar waveguides are good. The phase shifting technique has some limitations and need to be developed further.</p>
55

Design av mikrovågsövergångar / Design of microwave connections

Petersson, Björn January 2003 (has links)
In this Master thesis, microwave connections between circuit boards are constructed. The primary frequency band is the X-band (8-12 GHz). The purpose of the connections is to enable a more simple and cheaper way of mounting the circuit boards inside a container. The connections have been designed and evaluated, using different computer programs. A few prototypes have been built and measured. The main goal of this Master thesis was to design a connection, that would be useful in practice. The connections should be easy to manufacture and have a good performance. They should also have a high tolerance for manufacturing errors. The main part of this report contains descriptions of different designs. The designs are presented together with simulated and measured results. The report contains designs based upon coplanar waveguides and a phase shifting technique. The result shows that designs that are using coplanar waveguides are good. The phase shifting technique has some limitations and need to be developed further.
56

The impact of exogenous TGFβ1 on male reproductive function.

McGrath, Leanne Jane January 2008 (has links)
The TGFβ family of cytokines are potent signalling molecules that regulate tissue development, inflammation and immunity. Previous studies in mice with a null mutation in the Tgfb1 gene (TGFβ1-/- mice) implicate a key role for TGFβ1 in male reproductive function. These mice show profound infertility due to an inability to copulate successfully, associated with reduced testosterone and sperm production. The focus of this project was to 1) further characterize mechanisms underpinning reproductive deficiency in male TGFβ1-/- mice, 2) identify a reliable physiological marker of TGFβ1 availability in vivo, and 3) to determine whether exogenous TGFβ1 administration influences TGFβ1 availability and restores fertility. To investigate the causes of unsuccessful copulation by TGFβ1-/- mice, penis morphometry was examined. Penile organ structure, as assessed by scanning electron microscopy, was comparable between genotypes however a superfluous epidermal covering that impeded penile spine protrusion was evident in TGFβ1-/- mice. The epidermal covering was not due to increased epithelial cell proliferation, as measured by Brdu labelling and immunohistology. Behavioural observations of erectile activity showed that TGFβ1-/- mice achieved spontaneous erections albeit at reduced frequency compared to TGFβ1+/+ mice. The efficacy of exogenous TGFβ1 replacement was evaluated by first identifying measures of in vivo TGFβ1 availability and/or function and selecting an effective route of administration. Serum TGFβ1 and testosterone levels were reliable discriminators of TGFβ1 genotype. Gene expression and phagocytic function of peritoneal macrophages revealed no differences between genotypes. Exogenous sources of TGFβ1 for replacement studies included colostrum, naturally occurring in breast milk and recombinant human latent TGFβ1 (rhLTGFβ1). Colostrum did not increase circulating levels and rhTGFβ1 injection caused only transient elevation of serum levels. Thus mini-osmotic pumps were used to deliver a constant supply of cytokine to TGFβ1-/- mice. The fertility status of TGFβ1-/- mice receiving exogenous TGFβ1 was investigated. Reproductive behaviour in response to normal receptive female mice was assessed twice during treatment, on day 7 and day 14. Blood, liver and reproductive tissues were collected at sacrifice. Circulating TGFβ1 was increased in TGFβ1 treated TGFβ1-/- mice above TGFβ1-/- control levels, although this did not affect circulating testosterone. Erectile activity and sperm production were unchanged. Videotaping behaviour with estrous females revealed that the TGFβ1+/+ mice successfully mounted and intromitted, unlike the TGFβ1-/- controls. The TGFβ1-/- mice receiving exogenous TGFβ1 displayed moderately enhanced mounting and intromission behaviour although this remained less frequent than in the TGFβ1+/+ controls. Ejaculation behaviour was not observed in any TGFβ1-/- mice regardless of TGFβ1 replacement, compared to TGFβ1+/+ controls where >90% mice displayed ejaculated. Modest improvement in the copulation activity of the TGFβ1-/- mice receiving exogenous TGFβ1 suggests that systemic TGFβ1 availability can influence reproductive performance in male TGFβ1-/- mice. However since fertility was not restored, locally produced TGFβ1 in the reproductive tract and/or hypothalamic pituitary axis are also implicated in regulating fertility. These findings advance our knowledge of the role of the TGFβ1 cytokine in male reproductive physiology and may have relevance for devising new treatments for infertility and erectile dysfunction in men. / Thesis (Ph.D.) - University of Adelaide, School of Paediatrics and Reproductive Health, 2008
57

Vätskeslag i rörsystem : Experimentell utvärdering av rörstödens samt rörets utformning och dess inverkan på vätskeslag i rörsystem

Rhedin, Kristoffer, Mattsson Sjödin, Simon January 2018 (has links)
Studiens syfte är att identifiera en robust ingenjörsmetodik för approximation av sannolikhet och konsekvens (risken) vid vätskeslag i ett specifikt rörsystem. Arbetet har utförts i form av kvalitativa studier med verifierande experiment av analytiska beräkningsresultat.  Studiens resultat, vilka presenteras och diskuteras i slutsatskapitlet, visar på att vätskeslag kan predikteras och därigenom förebyggas med Joukowskys ekvation, vilken formulerades av Johannes von Kries 1883.  I de flesta fall kan ett rörsystems konstruktion optimeras mot oönskade tryckslags-konsekvenser genom omsorgsfullt val av lämpliga rörsystemskomponenter, såsom rördimensioner, ventiler, rörkrökningsradier och rörstödskonstruktioner. / This study’s objective has been to identify and evaluate a robust engineering method for the purpose of approximation and evaluation of a water hammer event in a specific pipe system design.  The study has been conducted in the form of qualitative studies with verifying experiments of the results from various analytical calculations.  The results presented and discussed in the last chapter of the essay, indicates that water hammer can be predicted and prevented by using Joukowsky's equation, formulated Johannes von Kries 1883.  In the most circumstances, pipe systems can be optimized to prevent water hammer consequences by selection of suitable components. Such as tube dimensions, valves, tube bending radius and the tube support design.
58

Návrh přední časti trupu letounu TL-4000 a zástavby motoru / Design of fore part of fuselage and engine mounting of TL-4000 aircraft

Löffelmann, František January 2014 (has links)
The thesis solves mounting of Continental IO-55ON to four-seat all composite aeroplane. Weight analysis of weights carried by engine mounting was done and loads of mounting and nose gear attached directly to mounting was computed according to CS-23 regulation. Mounting was designed based on affordable information about similar aeroplanes and it was sized due to Nastran/Patran system strength analysis. Further reinforcing of fire wall, engine covers and forms for their manufacture was suggested.
59

Zástavba turbovrtulové pohonné jednotky do malého dvoumístného letounu / Turboprop powerplant installation into small twoseater airplane

Kövér, Ondřej January 2018 (has links)
The diploma thesis deals with the problem of application of turboprop engine to a small 2-seater airplane. In the first part, reasons why the application is in considered are stated. Then, the air-plane is characterised, the choice of the most suitable engine, propeller and the weight analysis is made and the centres of gravity are calculated. For chosen engine and propeller, in chapter 6, the flight performance is calculated. In chapter 7 follows calculations of flight envelopes and the lim-it positive and negative load factor is stated. Flight envelopes calculations are followed by the calculation of engine mount loads of flight and ground cases. In chapter 9, the design of engine mount, inlet and outlet system and positioning of important elements are solved. The design part is followed by strength analysis of engine mount and its attachment into engine partition.
60

Zástavba pohonné jednotky LYCOMING do letounu Bristel UL / Installation of the LYCOMING power unit into the Bristel UL aircraft

Kročil, Petr January 2020 (has links)
This diploma thesis focuses on Lycoming drive unit mounting used in two-seater plane of VLA category (the very light aircraft). In the beginning characteristics of currently produced Bristell aircrafts are described. Following chapters aim at research selection of new drive unit mounting based on multi-criteria decision analysis. For selected unit, the weight, center of mass and flight performance are calculated. Additionally, the construction of engine mount is proposed. According to CS-VLA and CS-23 stress level of mounting is defined followed by strength verification. Later in this thesis, a suitable engine cover for engine and cockpit cooling is proposed. A complete fuel system is described in following chapter. Last chapter deals with financial costs of re-engining as well as aircraft operational costs.

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