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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.
21

Analysis of thermal effects in circumferential groove journal bearings with reference to the divergent zone / Analyse des effets thermiques dans les paliers hydrodynamiques avec une rainure circonférentielle en tenant compte de la zone divergente

Cristea, Alex Florian 12 December 2012 (has links)
Ce travail porte sur l'étude des effets thermiques dans un palier hydrodynamique, alimentée par une rainure circonférentielle (CGJB) sous charge statique, en tenant compte des phénomènes de rupture de film dans la zone divergente. La recherche expérimentale a été réalisée à l'Université de Poitiers ; elle a permis une détermination minutieuse des champs de pression et de température sur la portée située à l’avant d’un CGJB et dans la section médiane de sa rainure. Ces mesures sous un régime stationnaire sont originales par rapport celles existantes, quel que le type de palier, de par le grand nombre de points de mesure, 180 pour la pression et 144 pour la température, l'instrumentation de haute précision, la large plage de conditions d'exploitation (pression spécifique variant de 0,125 à 2 MPa et vitesse linéaire de l’arbre allant de 5,25 à 21 m/s). Des études du régime transitoire de démarrage au régime stationnaire établi ont été effectuées pour de faibles charges. Des expériences effectuées à l'Université "Politehnica" de Bucarest ont montré une bonne corrélation entre la perte de portance, anti-portance et la rupture du film sur un patin Rayleigh (RSP), ce qui est essentiel pour l'évaluation des phénomènes de rupture dans les paliers. Quelques modèles théoriques ont été utilisés pour évaluer les risques de serrage au démarrage qui est une instabilité thermoélastique catastrophique. Les principaux résultats sont l’obtention d’une base fiable de données expérimentales permettant le développement des modèles théoriques avancés et l’infirmation d’une répartition de pression constante dans la zone divergente et de pression et température constantes dans la rainure d'alime / The main objective of the thesis is to study the thermal effects in steadily loaded circumferential groove journal bearings (CGJBs), including cavitation phenomena occurring in the divergent zone of such bearings. Experimental research conducted at University of Poitiers – Institut Pprime – France enabled a thorough determination of film pressure and temperature fields for the front land of a CGJB plus its mid-groove section, and several performance parameters. Measurements of film pressure and temperature fields under steady-state regime surpassed existing works, regardless of journal bearing design, through: sheer number of land measurement locations, 180 for pressure and for 144 temperature; high precision state of art instrumentation; broad range of operating conditions, 0.125 … 2 MPa specific bearing pressure and 5.25 … 21 m/s shaft speeds. Transient start-up to steady-statestabilization regimes have been investigated at low loads. Experiments at University "Politehnica" of Bucharest – Romania showed a correlation between the downforce thrust and film rupture for a Rayleigh step pin (RSP), important in evaluating divergent zone cavitation phenomena. Theoretical research consisted in developing simple models for evaluating CGJBs performance in steady-state and transient start-up regimes. Several theoretical models were employed for assessing start-up seizure, catastrophic transient thermoelastic instability and damage risk. The major result is a reliable experimental data collection that: enables development of advanced theoretical models; disprove flat film pressure distributions in divergent zones, and constant pressure and temperature in the bearing supply groov
22

Administrativní budova JmP / Administrative building of South Moravian Gasworks

Žwaková, Vendula January 2013 (has links)
The subject of this Master’s thesis was recalculation and design two variants of existing supporting steel structure storey administrative building which is located in the complex of Jihomoravská plynárenská a.s. in the city center of Brno. Dimensions and disposition based on the specifications of the Master‘s thesis. The total height of the structure is 29.46 m and circular platform has a diameter of 16.088 m. The supporting structure of an existing building consists of circumferential lattice structure. The main supporting elements of both variants are columns. Option A has 8 columns. Option B has 16 columns. These two variants were preliminarily designed and statically evaluated. After that was made a comparison of variants, and one was selected for more detailed processing (Option A). This included the calculation of anchorage, draft of mounting joints, technical report and drawing documentation.
23

Sklad zemědělských hnojiv - stavebně technologická příprava / Warehouse of agricultural fertilizers - constructional and technological preparation

Kincl, Jakub January 2014 (has links)
In my master´s thesis i worked on construction and technological preparation of construction storage of agricultural fertilizers in Vilanec. This preparation includes summary expected work on construction, time and financial plan. Thesis in detail processes montage of prefabricate rod skelet and circumferential casing from PUR panels. Component of this thesis is proposal of needed mechanisation, control and probationary plan, plan of safety and protection of health upon work, proposal of building side, assessment of thermal proprties of structural construction, contract for work and EMS plan.

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