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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

Realizace tunelu Radejčín - vybrané části stavebně technologického projektu / Realization of tunnel Radejčín - the chosen parts of construction technological project

Hájek, Libor January 2012 (has links)
The issue of the thesis is a construction of the Radejčín highway tunnel. Project contains all of the stages of construction. The total budget and time schedule were made for complete structure. The technological instruction was made for secondary lining of the tunnel. There is also a plan of security instruction, the list of risks on construction site, suggestion of fixed job contract, the plan of controlls and exams for making invert and upper vault of secondary lining. Another part is the project of construction site with three different drawing of construction sites and text part. The list of machines and devices is for the complete construction. It was added also a chosen construction details and evaluation of geotechnical monitoring.
52

A probabilistic comparison of times to flashover in a compartment with wooden and non-combustible linings considering variable fuel loads

Studhalter, Jakob January 2012 (has links)
Prescriptive fire safety codes regulate the use of combustible room linings to reduce fire risk. These regulations are based on classification systems which designate materials according to their relative hazard when exposed to a standard fire scenario. However, no quantitative data sets on the fire risk of wooden lining materials exist which take into account relevant uncertainties, such as movable fuel loads in compartments. This work is a comparative risk analysis on the influence of wooden linings on the time to flashover in a compartment, considering uncertainties in the fuel load configuration. A risk model is set up for this purpose using B-RISK, a probabilistic fire design and research tool currently under development at BRANZ (Building Research Association of New Zealand) and the University of Canterbury. The risk model calculates fire spread in a compartment between fuel load items and from fuel load items to combustible linings. Multiple iterations are performed considering varying fuel load arrangements and input values sampled from distributions (Monte-Carlo simulation). The functionality and applicability of the risk model is demonstrated, comparing the model with experiments from the literature. The model assumptions are described in detail. Some of the model inputs are defined as distributions in order to account for uncertainty. Parametric studies are conducted in order to analyse the sensitivity of the results to input parameters which cannot be described as distributions. Probabilistic times to flashover are presented and discussed for an ISO 9705 compartment considering varying movable fuel loads and different lining configurations. The fuel load is typical for a hotel room occupancy. Effects of suppression measures are not considered. It is shown that flashover occurs approximately 60 seconds earlier if walls and ceiling are lined with wooden materials than if all linings are non-combustible. This value refers to the 5th percentiles of the time to flashover, i.e. in 5% of the cases flashover has occurred and in 95% of the cases flashover has not (yet) occurred. Referring to 50th percentiles (median values), the difference is approximately 180 seconds. Furthermore it is shown that with wooden wall and ceiling linings in approximately 95% of the iterations flashover occurs, whereas with non-combustible linings 86% of the iterations lead to flashover. After 900 seconds, in 90% of the iterations flashover occurs if walls and ceiling are lined with wooden materials, and in 77% of the iterations if the linings are non-combustible. Using different wooden lining materials (non-fire retardant plywood, fire retardant plywood, and MDF) has no significant effect on the probabilistic times to flashover. Varying the fuel load energy density has an influence only when all linings are non-combustible and when the fuel load energy density is relatively low (100–200 MJ/m2). This work contains recommendations regarding the further development of B-RISK, the research into the fire risk connected with wooden room linings, and suggestions regarding the further development of prescriptive fire safety codes.
53

Caracterização da espuma rígida de poliuretano (PU) derivada de óleo de mamona para isolamento térmico na construção civil / Characterization of rigid foam polyurethane (PU) derived from castor oil for building insulation.

Cardoso, Grace Tiberio 19 November 2010 (has links)
Este trabalho teve como objetivo o estudo da espuma rígida de poliuretano (PU) derivada de óleo de mamona para aplicação como forro na isolação térmica de sistemas de cobertura. Dentro deste objetivo foram caracterizadas as suas propriedades termomecânicas e avaliado o seu comportamento térmico quando aplicada como forro em células de teste em quatro situa-ções diferentes. As caracterizações termomecânicas da espuma rígida de poliuretano derivada de óleo de mamona foram realizadas utilizando as técnicas Termogravimétrica (TGA), Dinâ-mico-Mecânica (DMA), e Método do Fio Quente Paralelo. A técnica Termogravimétrica (TGA) possibilitou o estudo da decomposição da espuma e uma avaliação de sua cinética. A cinética de decomposição foi realizada em quatro diferentes razões de aquecimento e os resul-tados foram avaliados utilizando o método baseado no modelo de Ozawa-Flynn-Wall no qual foi possível estimar o tempo de vida da espuma rígida de poliuretano para vários valores de temperatura constante. Por meio da utilização da técnica Dinâmico-Mecânica (DMA) foi pos-sível determinar a temperatura de transição vítrea da espuma e os módulos viscoelásticos de armazenamento (E) e de perda (E) assim como os valores de Tan Delta. O Método do Fio Quente Paralelo proporcionou a determinação do valor da condutividade térmica da espuma, que a classificou como um material muito isolante (1).A espuma rígida de poliuretano apre-sentou propriedades termomecânicas compatíveis para utilização como isolante térmico em temperaturas abaixo da ambiente, e em temperaturas acima de 100 oC. O estudo comparativo entre quatro células de teste para análise do comportamento térmico do forro foi feito com a coleta de dados em canteiro experimental. Os resultados obtidos comprovaram a eficiência da espuma rígida de poliuretano derivada do óleo de mamona na redução da entrada de calor durante o período de radiação solar global máxima e a atenuação da perda de calor no período sem influência da radiação solar / This work aimed to study the rigid foam polyurethane (PU) derived from castor oil for appli-cation as lining in thermal insulation systems coverage. Within this objective we have charac-terized the thermomechanical properties and assessed its thermal behavior when applied as lining cells testing in four different situations. The rigid foam polyurethanes thermo characte-rizations, derived from castor oil, were performed using the Thermogravimetric Analysis (TGA), Dynamic Mechanical Analysis (DMA), and Hot Parallel Wire Method. The Thermo-gravimetric Analysis (TGA) has enabled the study of the foams decomposition and an evalu-ation of its kinetics. The decomposition kinetics was carried out in four various heating rea-sons and the results were evaluated using the method based on Ozawa-Flynn-Wall model which it was possible to estimate the rigid foam polyurethanes lifetime for various constant temperature values. By Dynamic Mechanical Analysis (DMA) has been possible to determine the foams glass transition temperature and the viscoelastics modules, storing module (E\') and loss module (E) well as the values of Tan Delta. The Hot Parallel Wire Method provided the valuation of foams thermal conductivity which ranked as a very insulating material (1). The rigid foam polyurethane has been shown to thermomechanical compatible for used as an insu-lator heat at temperatures below ambient, and temperatures above 100 oC. The four test cells comparative study for linings thermal behavior analysis was made with the collecting data from experimental plot. Results obtained proved the rigid foam polyurethane efficiency, de-rived from castor oil, in reducing the input heat during the maximum solar radiation and at-tenuation of heat loss in the period with no influence of solar radiation.
54

Fibromyalgia Impact and Suicidal Behavior: Conditional Indirect Effects of Anxiety and the Perception of a Silver Lining

Treaster, Morgan K., Rabon, Jessica K., Hirsch, Jameson K. 01 November 2016 (has links)
No description available.
55

Numerical Analysis of Leakage through Defective Geomembrane Liners in Embankment Dams

Demirdogen, Sarper 26 October 2018 (has links)
Placing a geomembrane liner in the core of a dam is an alternative construction technique to traditional clay core types. This study aims to assess the performance of such internal geomembrane sealing systems in an earthen dam. Two-dimensional (2D) numerical analysis was performed to evaluate leakage through defective seams within an earthen dam. Five possible applications of internal geomembrane systems were initially modeled to locate the zero-pressure lines in an earthen dam. Then, another application where the geomembrane is placed on the upstream face was modeled to compare the upstream and internal geomembrane systems. The results of this study show that use of a geomembrane system, either upstream or internal, significantly decreases the pore pressure at the downstream face of the earthen dam. In addition, limit equilibrium analysis was performed to evaluate the effects of leakage through defects in geomembranes on the dam stability. The stability analyses for the upstream and downstream slopes were performed for three loading conditions: (1) end of construction, (2) long-term, and (3) rapid drawdown. The frequencies and locations of defective seams had a significant impact on the factors of safety of the downstream slope. It is shown that, in the case of upstream geomembrane systems, the factor of safety for the downstream slope has the highest value when the geomembrane hole occurs at a relatively lower location. On the other hand, in the case of internal geomembrane systems, the highest factor of safety occurs when the geomembrane hole is at a higher location. Additionally, rapid drawdown simulations show that the upstream slope of an embankment dam must be flat enough to overcome the upstream stability issues when geomembranes are placed within embankment dams. This study not only showed the advantages of using a geomembrane in the core of a dam as an impervious lining system but also provided comparative information on the performance of internal and upstream geomembrane systems with respect to the stability in earthen dams.
56

Landfill Site Selection And Landfill Liner Design For Ankara

Yal, Gozde P 01 May 2010 (has links) (PDF)
The main scope of this thesis is to select alternative landfill sites for Ankara based on the growing trends of Ankara towards the Sincan and G&ouml / lbaSi municipalities and to eventually select the best alternative. Landfill site selection was carried out utilizing Geographic Information System (GIS) and Multi-Criteria-Decision-Analysis (MCDA). A number of criteria were gathered in a GIS environment. Each criterion was assigned a weight value by applying the Pairwise Comparison Method (PCM). &ldquo / The Technique for Order Preference by Similarity to the Ideal Solution (TOPSIS)&rdquo / , was applied and the best landfill site alternative was determined. The geotechnical properties of the clay samples, obtained from selected locations in G&ouml / lbaSi and Sincan were determined in order to design a landfill liner system using compacted &ldquo / Ankara Clay&rdquo / as the liner material. The permeability values for the clay samples were determined by performing falling head tests and consolidation tests. The coefficient of permeability value of the compacted clay was determined to be in the order of 10-10 m/s for the G&ouml / lbaSi samples and 10-11 m/s for the Sincan samples for both of the tests performed. These tests indicated that the native clay was suitable to be utilized as a landfill liner material. The HELP and POLLUTE was employed for the purpose of landfill design and predicting the landfill hydrological processes. The landfill profile with a double lining system composed of geomembrane/compacted clay composite top and bottom liners with a drainage layer was determined to show the best performance amongst the others.
57

Evaluation Of Structural Analysis Methods Used For The Design Of Tbm Segmental Linings

Cimentepe, Ahmet Guray 01 December 2010 (has links) (PDF)
Contrary to the linings of conventionally driven tunnels, the linings of tunnels bored by tunnel boring machines (TBMs) consist of precast concrete segments which are articulated or coupled at the longitudinal and circumferential joints. There are several analytical and numerical structural analysis methods proposed for the design of TBM segmental linings. In this thesis study, different calculation methods including elastic equation method and two dimensional (2D) and three dimensional (3D) beam &ndash / spring methods are compared and discussed. This study shows that in addition to the characteristics of concrete segments, the mechanical and geometrical properties of longitudinal and circumferential joints have significant effects on the structural behavior of segmental lining.
58

Influence of liquid diffusion on the performance of polymer materials in industrial applications

Römhild, Stefanie January 2007 (has links)
<p>Diffusion of liquids into and through polymers is an important factor that negatively may influence the durability or lifetime of a polymer structure used in industrial applications. In this work two types of polymers, a liquid crystalline polymer (LCP, Vectra A950) and various thermoset resins as used in fibre reinforced plastics (FRP) process equipment were studied with regard to barrier properties, chemical resistance and long-term performance. LCP are known for their outstanding chemical resistance and barrier properties. FRP used in process equipment may be a cost-efficient solution in chemically aggressive environments where standard carbon or stainless steel cannot be used due to its limited corrosion resistance. Transport properties of typical industrial environments were determined for the LCP and the influence of annealing and orientation was investigated to study whether the barrier properties can be improved. The possibility to use LCP as cost-effective lining for FRP was explored. Special focus was put on the diffusion of water and its effect on long-term transport properties and stability of thermoset resins as the performance of FRP is strongly related to the diffusion of water. </p><p>The results showed that Vectra A950 was suitable for organic solvent and non-oxidising acid environments. Its transport properties were gravimetrically determined and found to be 10 to 102 times lower than that of a high barrier fluoropolymer of type FEP. The degree of molecular packing increased with annealing time both below and above the melting point. Below the melting point this was – at least – partly due to crystal formation whereas above the melting point other mechanisms were involved. The effects of annealing and orientation on the transport properties in LCP were, however, very small or not significant and probably significantly longer annealing times are required. LCP has potential to be used as lining material for FRP as the use of an LCP-lining substantially reduced the permeability of and the solute sorption in a bisphenol A epoxy-based vinyl ester resin. The bonding strength was improved significantly by a combined abrasive and oxygen plasma treatment.</p><p>The long-term sorption of water in thermoset resins including bisphenol A epoxy-based vinyl ester, novolac-based vinyl ester, urethane modified vinyl ester and bisphenol A polyester resins was found to increase with exposure time whereas the diffusion coefficient was not significantly affected. It was shown that the presence of water induced relaxation processes that were considered to be the primarily reason for the increase in sorption coefficient in comparison to degradation processes, such as hydrolysis, causing osmotic processes. A general relationship for the estimation of the sorption coefficient at 80ºC in dependence of the water activity and the sorption coefficient at unit activity independent of the resin type was established.</p>
59

Microdureza de cimentos de ionômeros de vidro indicados para a técnica do ART, variando-se a proteção superficial e o tempo de armazenamento

Shintome, Luciana Keiko [UNESP] 25 June 2007 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:31:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-06-25Bitstream added on 2014-06-13T19:41:13Z : No. of bitstreams: 1 shintome_lk_dr_sjc.pdf: 280293 bytes, checksum: 55405500ef310209c685206fa028963c (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste estudo foi avaliar a microdureza de cimentos de ionômero de vidro (CIV): Vidrion R (V) .- SS White; Fuji IX (F) . GC Corp; Magic Glass ART (MG) - Vigodent; Maxxion R (MR) - FGM e ChemFlex (CF) - Dentsply, na presença ou ausência de proteção superficial, em diferentes períodos de armazenamento. Para cada CIV foram confeccionados 36 corpos-de-prova (3 mm altura X 3 mm diâmetro), divididos em 3 grupos em função da proteção superficial (sem proteção, verniz do Fuji IX ou esmalte para unha). Os espécimes foram armazenados em água destilada por 24 h, 7 e 30 dias e os testes de microdureza foram realizados nestes tempos. Os dados obtidos foram submetidos ao teste de ANOVA para medidas repetidas e teste de Tukey ('alfa'=5%), e revelaram que os valores médios de microdureza, no geral, em ordem decrescente dos CIV foram: F > CF = MR > MG > V; que a proteção superficial foi significante para o MR em 24 h sem proteção (64,2'mais ou menos'3,6a), proteção com verniz (59,6'mais ou menos'3,4b) e com esmalte (62,7'mais ou menos'2,8ab); para o F, em 7 dias, sem proteção (97,8'mais ou menos'3,7ab), proteção com verniz (95,9'mais ou menos'3,2b) e com esmalte (100,8'mais ou menos'3,4a) e em 30 dias para o F sem proteção (98,8'mais ou menos'2,6b), proteção com verniz (103,3'mais ou menos'4,4a) e com esmalte (101'mais ou menos'4,1ab) e V sem proteção (46'mais ou menos'1,3b), proteção com verniz (49,6'mais ou menos'1,7ab) com esmalte (51,1'mais ou menos'2,6a) e o aumento do tempo de armazenamento proporcionou um aumento da microdureza. Concluiu-se que os diferentes CIV, tipo de proteção e tempo de armazenamento, podem alterar os valores de microdureza... / The aim of this study was to evaluate the microhardness of glass ionomer cement (GIC): Vidrion R (V) - SS White; Fuji IX (F) - GC Corp.; Magic Glass ART (MG) - Vigodent; Maxxion R (MR) - FGM and ChemFlex (CF) - Dentsply, with or without surface protection in different storage time. Thirty six specimens for each GIC (3 mm diameter X 3 mm height) were made and these specimens were divided into three groups, according to the surface protection (without protection, varnish protection of the Fuji IX or protection with nail varnish). The samples were stored in distilled water for 24 h, 7 and 30 days and the microhardness test was carried out using a microhardner in those times. The data were submitted to repeated measures analysis of variance test and Tukey test ('alfa' =0.05) and showed that mean microhardness values, in general, of the GIC followed the decrescent order: F > CF = MR > MG > V; the surface protection was significant for MR in 24 h without protection (64.2'mais ou menos'3.6a), protection with varnish (59.6'mais ou menos'3.4b) and nail varnish (62.7'mais ou menos'2.8ab); for F in 7 days without protection (97.8'mais ou menos'3.7ab), protection with varnish (95.9'mais ou menos'3.2b) and nail varnish (100.8'mais ou menos'3.4a); for F in 30 days without protection (98.8'mais ou menos'2.6b), protection with varnish (103.3'mais ou menos'4.4a) and nail varnish (101'mais ou menos'4.1ab) and for V in 30 days without protection (46'mais ou menos'1.3b), protection with varnish (49.6'mais ou menos'1.7ab) and nail varnish (51.1'mais ou menos'2.6a) and surface microhardness generally increased with time. It was concluded that different trade mark, surface protection and storage times can influence microhardness of GIC.
60

Produção de gesso reciclado a partir de resíduos oriundos da construção civil. / Plaster recycled production from waste and residues originating from a building site

Ribeiro, Abrahão Severo 24 March 2006 (has links)
Made available in DSpace on 2015-05-14T12:09:42Z (GMT). No. of bitstreams: 1 parte2.pdf: 2250705 bytes, checksum: a9adef250fa0917a5b76e0591475bc50 (MD5) Previous issue date: 2006-03-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Comparing to others binders, as Portland cement and lime, plaster is much more energetic efficient because it can be obtained at relatively low temperatures (less than 160oC). During its making process, it emits water vapor to atmosphere, instead CO2 produced by the others binders named above. Although, being a calcium sulfate that has some water solubility, irregular deposition of its residues can contaminate ground and natural source of water The resolution 307/02 of Brazilian National Environmental Council considers plaster as class C material, so, a material that generates residues for those technologies or feasible applications were not still developed to permit a recycling. Then, it is necessary to change this reality and to find a way to minimize plasters residues to environment. In this work, a possibility to obtain plaster from residues of four of its applications in civil construction (coating, sealing plates, decoration pieces, ceramic moulds) was investigated. Initially, the plaster residues volume generated at Recife Metropolitan Area was researched. After, physical, chemical and mechanical properties were obtained. X ray difractometry showed much alike between the recycled plasters and natural plaster. The same occurred with mechanical strength. Despite some small differences on others properties (as lower initial and final set time) results indicate that it is possible to recycle plaster residues. For this it is necessary to separate it of others construction materials residues in the construction site / Comparado com outros ligantes como cimento Portland e mesmo cal, o gesso apresenta muito maior eficiência energética, visto que pode ser obtido em temperaturas inferiores a 160°C. No seu processamento, ele lança na atmosfera vapor d´água, contrariamente aos dois primeiros produtos citados que emitem CO2 no seu processo de fabricação. No entanto, sendo um sulfato de cálcio que apresenta certa solubilidade em água, a deposição irregular de seus resíduos pode contaminar solos e águas. A resolução 307/02 do Conselho Nacional do Meio Ambiente considera o gesso como material classe C, ou seja, aquele que gera resíduos para os quais não foram desenvolvidas tecnologias ou aplicações economicamente viáveis que permitam uma reciclagem. Urge então reverter essa situação e encontrar formas de se minimizar a dispersão dos resíduos de gesso no meio ambiente. Uma delas é justamente promover o reaproveitamento desses resíduos. Neste trabalho foi estudada a possibilidade de obtenção do gesso a partir de resíduos de quatro de suas aplicações na construção civil: revestimento de alvenarias, placas de forro, peças de decoração, moldes para cerâmica. Inicialmente foi quantificado o volume de resíduos de gesso gerados na Região Metropolitana do Recife. Em seguida foram coletados os quatro citados tipos de resíduos. Estes materiais foram beneficiados em Laboratório e recalcinados. Em seguida foram feitos os ensaios de caracterização de suas propriedades químicas, físicas e mecânicas. Os resultados de difractometria de raios X mostraram muita semelhança entre os resíduos de gesso e a gipsita. O mesmo ocorre com as resistências mecânicas. Apesar de algumas diferenças em outras propriedades (como tempos de inicio e fim de pega) os resultados deste trabalho apontam para a possibilidade de se obter gesso a partir dos resíduos gerados na indústria da construção civil,xviii devendo-se ter o cuidado de separar nas obras esse material de contaminações com outros resíduos de construção.

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