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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.
1281

A study on the effects of sidewall insulation on the performance of exterior paint finishes on frame, wood-clad historic houses

Zmyslo, Ronald J. 15 December 2012 (has links)
Presently, there exists a large number of historic houses that have had their walls insulated with loose-fill cellulose and can now be studied 10, 20 or 30 years after they were insulated. The wood siding of these houses can be evaluated for types of paint failure and compared to comparable historic houses that have not had their sidewalls insulated. A methodology for defining common paint failure types, their presence and possibly their severity was designed. A methodology for the selecting of historic houses with both insulated and uninsulated walls was also designed. A visual documentation process was carried out, results compiled and analyzed in order to determine if a difference could be observed between the types of paint failures on the insulated versus the uninsulated historic houses. In addition this study looked at the most common sources for moisture intrusion into a wall cavity, how this moisture moves, and how little the role of vapor diffusion plays in the wetting of the wall cavity. / Moisture and paint failure -- Understanding moisture movement in buildings -- How frame walls get wet -- How insulation might affect how frame walls get wet and how they dry -- Strategies for controlling moisture -- Other causes of exterior paint failure unrelated to moisture within the wall -- Field work -- Types of paint failure -- Case study houses -- Summary and conclusion. / Department of Architecture
1282

Impact of land cover and antecedent moisture content on runoff discharge in the West Fork of the upper White River, Indiana

Al-Mefleh, Naji K. January 2003 (has links)
There is no abstract available for this dissertation. / Department of Natural Resources and Environmental Management
1283

Tilläggsisolering och fuktproblem i grundkonstruktionen platta på mark : En fallstudie i flerbostadshus inom stadsdelen Sätra i Gävle

Blom, Linus, Hedlund, Dan January 2014 (has links)
Between 1965 and 1974, the Swedish Parliament decided to build one million dwellings, called Million Program. The million program buildings were erected with new, untried design solutions, in a short range of time, and at low cost. The residential buildings from that time are now greatly in need of renovation. The municipal housing company, Gavlegårdarna, renovates and improves the energy efficiency at some of it’s apartment buildings in the district Sätra, Gävle. One problem is how to make the basic design of the slab on ground more energy efficiency and moisture proof. The study covers four representative flooring types in the Gavlegårdarnas million program area in Sätra. This study aims to investigate and evaluate proven methods for adding insulation in the four floor types. Also to look for solutions by designing additional insulation to treat damp problems and improve energy efficiency in an economical way. Existing flooring types are to be examined to check for new solutions as well. The aim is to produce a number of measures to provide property owners with different energy efficiency solutions. Results of calculations show that the perimeter area of the slab is exposed to moisture problems, while the centre of it does not have any notable problems. According to calculations, improved floor types have U-values reduced by 31% – 40% depending on the insulation thickness and design. However, investments have a long payback period and this is sometimes not economically viable. When a redevelopment project is performed, it is beneficial to simultaneously add insulation. If investors promote sustainable development, reduced energy consumption by the proposed measures is viable, as advocated by the environmental goals set by Sweden and the EU. / Sveriges riksdag beslutade att det skulle byggas en miljon bostäder, så kallade miljonprogramshus, mellan åren 1965 och 1974. Miljonprogramshusen uppfördes med nya och obeprövade konstruktionslösningar, på kort tid och till låga kostnader. Idag är bostadshusen från den tiden i stort behov av renovering. Det kommunalägda bostadsbolaget Gavlegårdarna håller på att renovera och energieffektivisera några av sina flerbostadshus i stadsdelen Sätra, Gävle. Ett problem är hur grundkonstruktionen, platta på mark i flerbostadshusen ska energieffektiviseras och fuktsäkras. Denna undersökning behandlar fyra representativa golvkonstruktioner som förekommer i Gavlegårdarnas miljonprogramsområde i Sätra. Syftet med undersökningen är att studera och utvärdera beprövade metoder för tilläggsisolering på de fyra utvalda golvtyperna. Lösningsförslagen på tilläggsisoleringsåtgärderna ska behandla fuktproblem, ekonomi och energieffektivisering. Resultaten från undersökningen visar att markplattans kantbalk är utsatt för fuktproblem medan plattans mitt inte har några anmärkningsvärda problem. Enligt U- värdesberäkningarna förbättras golvtypernas U-värde med 31 % - 40 % beroende på isoleringstjocklek och utförande, dock har investeringarna långa återbetalningstider. Utförs ett renoveringsarbete är det fördelaktigt att samtidigt tilläggsisolera. Satsar investerarna på en hållbar utveckling med minskad energianvändning rekommenderas förslagna åtgärderna, vilket förespråkas i miljömål uppsatta av Sverige och EU.
1284

Investigation into Asphalt Concrete Material and Volumetric Properties that Promote Moisture Damage

Lambert, Jean-Luc 19 September 2013 (has links)
The research presented in this thesis: (1) quantifies and qualifies the Surface Free Energy (SFE) of neat and Liquid Anti-Strip (LAS) modified asphalt binders (binder); and (2) identifies volumetric mix properties that inhibit or assist in the susceptibility of Hot Mix Asphalt (HMA) to moisture damage based on time dependent phenomenological mechanical responses. These two research elements provide insight into the physical, chemical, mechanical and volumetric mix properties that inhibit or facilitate moisture damage in HMA. Moisture damage is a mechanism that causes distress and failure in asphalt concrete (AC) pavements due to a loss of durability resulting from the presence of moisture, in the form of a vapour or liquid, originating internally or externally. This reduces the pavements performance by promoting distresses such as: longitudinal cracking, spalling, rutting, shoving, stripping and ravelling. When moisture originates or is introduced in the AC a weakening of adhesion and cohesion of the material occurs, due in part to: binder properties, aggregate properties, volumetric mix properties, environmental conditions, traffic volume and loads, pavement design and construction practices. The research performed was split in two parts. The first part consisted of conducting SFE measurements on two PG 58-34 binders with different sources. One binder was modified with a LAS agent at concentrations of 0.5%, 2.0% and 5.0% by mass of binder and the other binder was kept neat. The neat and LAS modified binders were subjected to short-term aging by oxidation and then tested with a goniometer to determine their SFE and wettability. The SFE measurements revealed that an LAS concentration of 0.5% maximizes: (1) the work of adhesion of an unaged and aged binder, and (2) the ability of the binder to repel water. Furthermore, the process of aging increases the hydrophobicity or tendency of the binder to repel water regardless of the LAS concentration. Hence, an LAS concentration of 0.5% minimizes the potential for moisture damage in HMA. The second part of the research consisted of investigating the potential for moisture damage of seven bituminous type B (Bit B) and eight bituminous type C (Bit C) mix specified by Manitoba Infrastructure and Transportation. Laboratory testing of the resilient modulus and creep compliance was conducted to determine the fundamental mechanical response of the material. The resilient modulus and creep compliance test program were conducted on samples before and after moisture conditioning. As a result of the testing program, it was observed that the susceptibility of AC to moisture damage based on volumetric mix properties can be dependent on the air voids ratio, aggregate gradation and binder content of the mix.
1285

ANALYSIS FOR AN ECONOMICALLY SUITABLE COAL TO PUTTALAM COAL POWER STATION TO RUN THE PLANT IN FULL LOAD CAPACITY

Weerathunga, Lahiru January 2014 (has links)
Sri Lanka is an island at the Indian Ocean with 65234 km2 and it has a power demand of 2000 MW. The hydro power was the main power source before year 2000, after maximum usage of hydro power Sri Lanka installed fossil fuel power plant to achieve the demand. Then the electricity price gradually increased due to higher increment of fuel price. As the solution for this higher price of electricity the government has to go to new profitable power source the coal power. Finally year 2011 Puttalam coal power plant 300 MW x 1 was installed with the hope of providing the low cost reliable energy supply to Sri Lanka and it will be extended to 300MW x 3 plan in year 2015. Therefore the puttalam coal power plant is the key power plant to the Sri Lankan power generation and it is expected to have the maximum output (base load) to the Power demand of Sri Lanka. Sri Lanka is a tropical country and it has two different weather seasons as rainy season and dry season. The puttalam power plant situated at Kalpitiya peninsula and it has normally dry weather condition, Months of April, October November and December have heavy rain condition (Meteorological Department, Sri Lanka, 2012). The puttalam coal power plant may not achieve full load because of high moisture content at rainy season. So this Thesis carried out to find the capability to achieve the full load with available plant, plant capacity by using different coal qualities. Then find the economical benefits and effect on the environment with the recommended coal for different seasons and also design a storage plan to coal storage at existing coal yard. Based on the historical data and the Meteorological department rain fall data and by doing a technical analysis the recommended coal type was selected and the capability of plant equipment capacity to the recommended coal to achieve the full load was analyzed. Then the coal storage plan was designed according to annual requirement of the different recommended coal and economical benefit was analyzed by considering last year cost for generated power and the generation cost, if recommended coal is used for last year. Finally flue gas analysis was carried out for the recommended coal to find the effect on the environment. The recommended coal for rainy season is with the heating value of 6600 kcal/kg and for dry season it is 6300 kcal/kg. The capacities of main boiler and other plant equipments are capable for the recommended coal to achieve the full load of the plant. Then the design of the coal storage plan was given under figure 4.2 and table 4.1. It was calculated that a profit of 3.932 million US$ can be achieved by using the recommended  coal for the last year and also when compared with the changing price of oil and coal it will be more profitable for the future. Because the oil price increases very rapidly and the increase in coal price is very low compared to the oil price. Finally the SOx and NOx emissions from recommended coal were analyzed and it was within the environmental limits because of the high quality emission reduction plant equipments.
1286

Characterization of Forest Harvest Residue from the Great Lakes-St Lawrence Forests of South-eastern Ontario

Acquah, Gifty Ewurama 14 December 2010 (has links)
The use of fossil derived products and the environmental and economic problems associated with them have made a shift to abundant renewable resources such as forest biomass more attractive. However before forest biomass can be used as a resource, its properties must be known. This study determined the physical properties of heterogeneous biomass residues produced during harvesting on two operational forest sites within the Great Lakes-St Lawrence forest of south-eastern Ontario. Properties measured were moisture content, size distribution, bulk density, and wood-to-bark ratio; also thermo-chemical properties including elemental composition, thermal reactivity and energy content were measured. The effects of forest site and harvest type, storage and position in storage pile, on the properties of biomass were also investigated. Results of the study showed that the various heterogeneous forest harvest residues differed more physically than thermo-chemically for the different variables, and this affected biomass procurement more than the potential utilization options.
1287

Indoor Environmental Factors and Chronic Diseases in Swedish Pre-School Children : Risk factors and methodological issues investigated in a longitudinal study on airway diseases and autism spectrum disorder

Larsson, Malin January 2010 (has links)
Asthma and allergies have increased considerably during the past 40-50 years. Along with this increase, a heightened awareness regarding different neuro-developmental disorders such as autism spectrum disorder has occurred and it has been proposed that such disorders are also on the increase. It has been suggested that environmental factors, especially in the indoor environments, may be associated with the increase in these disorder, especially among children, who spend more than 90% of their time indoors. The aim of this thesis has been to investigate certain environmental factors in homes and their impact on children’s health, in terms of asthma, rhinitis, eczema as well as autism spectrum disorders, and to identify certain methodological difficulties in epidemiological investigations. We found that the mean incidence rate per year for doctor diagnosed asthma was in the range of 0.6-2.4% and for incidence of rhinitis 1.1-3.7%. The incidence rate of eczema ever was 2.7%. These results showed that when using a cohort established after birth the estimated incidence rates are strongly dependent of how the baseline population’s health and how the studied health outcome at follow up is defined. Our results showed that the associations between parental reported moisture problems in the home and asthma in children that were revealed in cross-sectional analyses decreased or disappeared when longitudinal data were used on the same data set. Our results therefore indicate that associations between parental reported moisture problems and asthma from cross-sectional questionnaire studies should be interpreted with caution due to the risk for reporting bias. Our results show that children who were living in homes with PVC-flooring in the bedroom in early childhood were more likely to develop asthma during the following 5-year period when compared with children living in homes without such flooring material. A similar association could be seen for children with autism spectrum disorder, where PVC-flooring in early childhood was associated with more reports of autism spectrum disorder five years later. These results indicate that building materials including suspected endocrine disrupting chemicals such as phthalates might be of importance for the development of these chronic diseases. Further studies are needed to explore the early life exposure and the mechanisms and contribution of phthalates for the development of chronic diseases. / Appendix A (en undersökning) och Appendix B (en undersökning)finns i den tryckta versionen av avhandlingen
1288

Experimental investigation and constitutive modelling of thermo-hydro-mechanical coupling in unsaturated soils.

Uchaipichat, Anuchit, Civil & Environmental Engineering, Faculty of Engineering, UNSW January 2005 (has links)
A thermo-elastic-plastic model for unsaturated soils has been presented based on the effective stress principle considering the thermo-mechanical and suction coupling effects. The thermo-elastic-plastic constitutive equations for stress-strain relations of the solid skeleton and changes in fluid content and entropy for unsaturated soils have been established. A plasticity model is derived from energy considerations. The model derived covers both associative and non-associative flow behaviours and the modified Cam-Clay is considered as a special case. All model coefficients are identified in terms of measurable parameters. To verify the proposed model, an experimental program has been developed. A series of controlled laboratory tests were carried out on a compacted silt sample using a triaxial equipment modified for testing unsaturated soils at elevated temperatures. Imageprocessing technique was used for measuring the volume change of the samples subjected to mechanical, thermal and hydric loading. It is shown that the effective critical state parameters M, ???? and ???? are independent of temperature and matric suction. Nevertheless, the shape of loading collapse (LC) curve was affected by temperature and suction. Furthermore, the temperature change affected the soil water characteristic curve and an increase in temperature caused a decrease in the air entry suction. The simulations from the proposed model are compared with the experimental results. The model calibration was performed to extract the model parameters from the experimental results. Good agreement between the results predicted using the proposed model and the experimental results was obtained in all cases.
1289

Water Movement in Unsaturated Concrete: Theory, Experiments, Models

Leech, Craig Anthony Unknown Date (has links)
Prediction of contaminant transport in concrete subjected to short cyclical wetting and drying processes is integrally bound to prediction of the moisture flux. The concrete is unsaturated and the non-linear contaminant and moisture fluxes are not described by simple constant diffusion methods. This thesis presents, and partially justifies, a thermodynamic model for prediction of moisture movement in concrete, at all moisture contents commonly encountered. The wetting process is examined with Nuclear Magnetic Resonance (NMR) images during a simple absorption (sorptivity) experiment. Diffusivity functions are derived via a novel analytical approach and a universal diffusivity is suggested. Water sorption and desorption isotherms are measured on large concrete samples. van Genuchten’s retention function is successfully used to model the results. The unrelia-bility of the water sorption method at high moisture contents is illustrated by comparison with Mercury Intrusion Porosimetry (MIP). The BJH method is exploited to provide a methodology for estimating the water sorption isotherm from MIP. Mualem’s conductivity model is assessed with the water retention and NMR results. This thorough validation of the model yields a tortuosity parameter that is different to that commonly assumed. An analytical relationship between the sorptivity and the saturated permeability suggests the experimental the long-term unsaturated permeability overesti-mates the unsaturated conductivity function, and as such should be used judiciously when predicting unsaturated flow processes. Mualem’s conductivity model is further exploited to provide unsaturated air and vapour functions that are experimentally justified. The thermodynamic description of water movement and the hydraulic functions that are developed in the thesis are incorporated into T r inCet , a transient heat and mass trans-fer model based on the Finite Element Method (FEM). The complex coupled behaviour of air, liquid, vapour and temperature are well handled under a variety of common cyclical boundary conditions. The thesis presents all necessary experimental results required for validation of a com-plex, but easily described, model for moisture movement. It covers disparate ground to provide a powerful numerical model of unsaturated moisture movement in concrete under short-term cyclical processes.
1290

Water Movement in Unsaturated Concrete: Theory, Experiments, Models

Leech, Craig Anthony Unknown Date (has links)
Prediction of contaminant transport in concrete subjected to short cyclical wetting and drying processes is integrally bound to prediction of the moisture flux. The concrete is unsaturated and the non-linear contaminant and moisture fluxes are not described by simple constant diffusion methods. This thesis presents, and partially justifies, a thermodynamic model for prediction of moisture movement in concrete, at all moisture contents commonly encountered. The wetting process is examined with Nuclear Magnetic Resonance (NMR) images during a simple absorption (sorptivity) experiment. Diffusivity functions are derived via a novel analytical approach and a universal diffusivity is suggested. Water sorption and desorption isotherms are measured on large concrete samples. van Genuchten’s retention function is successfully used to model the results. The unrelia-bility of the water sorption method at high moisture contents is illustrated by comparison with Mercury Intrusion Porosimetry (MIP). The BJH method is exploited to provide a methodology for estimating the water sorption isotherm from MIP. Mualem’s conductivity model is assessed with the water retention and NMR results. This thorough validation of the model yields a tortuosity parameter that is different to that commonly assumed. An analytical relationship between the sorptivity and the saturated permeability suggests the experimental the long-term unsaturated permeability overesti-mates the unsaturated conductivity function, and as such should be used judiciously when predicting unsaturated flow processes. Mualem’s conductivity model is further exploited to provide unsaturated air and vapour functions that are experimentally justified. The thermodynamic description of water movement and the hydraulic functions that are developed in the thesis are incorporated into T r inCet , a transient heat and mass trans-fer model based on the Finite Element Method (FEM). The complex coupled behaviour of air, liquid, vapour and temperature are well handled under a variety of common cyclical boundary conditions. The thesis presents all necessary experimental results required for validation of a com-plex, but easily described, model for moisture movement. It covers disparate ground to provide a powerful numerical model of unsaturated moisture movement in concrete under short-term cyclical processes.

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