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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.
881

Fuktproblematiken : En studie om fuktsäkerhet på byggarbetsplatsen / Moisture problems during the production phase : A study concerning moisture safety on the construction site

Thuresson, Henrik, Persson, Fredrik January 2007 (has links)
Kostnaderna för fuktskador i Sverige uppskattas årligen uppgå till mångmiljard belopp. Fuktskador i byggnader medför också en ökad risk för ohälsa hos brukarna. Kunskapen för att producera fuktsäkra byggnader finns men utnyttjas inte i den omfattning den borde. Den 1 juli 2007 träder en ny upplaga av Boverkets byggregler i kraft. Förtydliganden har gjorts i avsnittet gällande fukt, vilka underlättar verifieringen av entreprenadens fuktsäkerhet. Reglerna innefattar också krav på kritiska fukttillstånd i material. Denna studie syftar till att kartlägga brister i produktionsskedet och hur produktionen kan utvecklas för att motsvara de i Boverkets byggregler ställda krav på fuktsäkerhet. Intervjuer har förts med olika representanter i byggbranschen för att ge en helhetssyn av fuktproblematiken. Göran Hedenblad vid Boverket menar att tillsynen och kontrollen av fukt kan och måste bli bättre på byggarbetsplatsen. Fuktkonsulten Tord Nilsson hävdar att de nya kraven innebär ett paradigmskifte som medför stora förändringar på dagens sätt att producera byggnader. De intervjuer som gjordes med beställare och entreprenör visar dock på både bristande fuktkunskap och bristande strategi för att nå ett fuktsäkert byggande. Vid fältstudien påvisades brister i produktionen med avseende på skydd av material och konstruktion, uttorkning och utförandet av fuktkvotsmätningar. Många av dessa brister härrör från att fuktproblematiken inte har en central roll vare sig i program-, projekteringseller produktionsskedet. Vidare konstateras att kunskapsnivån för att hantera fukt kan utvecklas hos all personal och i alla delar av byggprocessen. Av de observationer som gjorts under fältstudien har åtgärdsförslag till en ökad fuktsäkerhet sammanställts i rapporten. Vidare har ett informationsblad utarbetats för att informera om fukt och dess skadeverkningar samt att ge några förslag till åtgärder som kan förbättra fukthanteringen ute på byggarbetsplatsen. Informationsbladet bör placeras på byggarbetsplatsen för att stödja entreprenören i sitt fuktsäkringsarbete. Eftersom ramverket för projektet är fastslaget då produktionsfasen tar vid innebär detta begränsningar för fuktsäkerhetsarbetet. För att skapa bättre förutsättningar för en fuktsäkrare produktion anser vi att en fuktsakkunnig skall anlitas så tidigt som möjligt i projektet. / The costs regarding moisture damages in buildings in Sweden are expected to reach several billions SEK each year. These moisture damages also result in an increased risk regarding health issues among the users. The knowledge of how to produce moisture secure buildings exists, but it is not beeing used to the extent it could be. The first of July 2007 a new edition of Boverket´s regulations regarding buildings takes effect. Boverket is the Swedish board of housing, building and planning. Clarifications have been made concerning moisture issues which facilitate the verifications of moisture security in the chain of building production. The regulations also contain demands according to critical levels of moisture in building materials. This study is meant to survey errors in the production phase and how the production can develop to correspond to the regulations stated by Boverket regarding moisture safety. We interviewed different representatives in the building sector to give a general impression of the moisture issues. Göran Hedenblad at Boverket states that the supervision and control regarding moisture on the construction site can and must be improved. The moisture consultant Tord Nilsson believes that the new demands will result in huge changes concerning the way buildings are produced. The interviews carried out with the future proprietor and the contractor displayed a lack of knowledge and strategy concerning how to produce moisture secure structures. The field study pointed out incongruities concerning how building materials and the constructions were protected from moisture influence, evaporation and the control of the moisture levels in the structure. Many of these flaws originate from the fact that moisture issues are not a central matter, neither in the phase of planning nor production. Further it can be established that the level of knowledge regarding how to deal with moisture problems can be developed among all personnel and sectors in the building process. The observations implemented during the field study have resulted in several preventive measures which are compiled in this thesis. Further has an information sheet been put together with the purpose to inform about these preventive measures and the damages moisture inflicts upon structures and human beings. The information sheet should be placed on the construction site to support the contractors in their work for a more moisture safe production.
882

The climate of the Rupununi Savannas : a study in ecological climatology.

Frost, David B. January 1966 (has links)
The intent of this thesis is to set out new data relating to the climate of the savanna in the Rupununi district of Guyana, and to comment thereon with reference to the causes and continuing existence of that savanna. To indicate the significance of the data and the pertinence of the comments it will be necessary to review recent discussion of the nature and causes of savanna in general. [...]
883

A Multitemporal Analysis of Georgia's Coastal Vegetation, 1990-2005

Breeden, Charles, III F 17 April 2008 (has links)
Land and vegetation changes are part of the continuous and dynamic cycle of earth system variation. This research examines vegetation changes in the 21-county eco-region along coastal Georgia. The Advanced Very High Resolution Radiometer (AVHRR) with Normalized Difference Vegetation Index (NDVI) data is used in tandem with a Principal Component Analysis (PCA) and climatic variables to determine where, and to what extent vegetation and land cover change is occurring. This research is designed around a 16 year time-series from 1990-2005. Findings were that mean NDVI values were either steady or slightly improved, and that PC1 (Healthiness) and PC2 (Time-Change) explained nearly 99 percent of the total mean variance. Healthiness declines are primarily the result of expanding urban districts and decreased soil moisture while increases are the results of restoration, and increased soil moisture. This research aims to use this analysis for the assessment of land changes as the conduit for future environmental research.
884

Drėgmės trūkumo poveikis žaliosios šerytės morfofiziologiniams parametrams / Effect of moisture deficit on morphophysiological parameters of green millet

Kopūstas, Aurentas 21 June 2013 (has links)
Magistrantūros studijų pateikiami drėgmės deficito poveikio žaliosios šerytės morfofiziologiniams parametrams tyrimų rezultatai. Darbo objektas – žalioji šerytė (Setaria viridis (L.) P. Beauv.). Darbo metodai: žaliosios šerytės augalai auginti programuojamoje auginimo kameroje esant 20/18 °C (diena/naktis) temperatūrai, 16/8 val. (diena/naktis) fotoperiodui, 50 µmol m-2 s-1 apšviestumui. IV organogenezės tarpsnyje augalai auginti esant drėgmės deficitui substrate. Vertintas fotosintetinių pigmentų kiekiai, augalo žalia masė, sausos medžiagos kiekis bei santykinis vandens kiekis lapuose. Darbo rezultatai. Esant nedideliam drėgmės trūkumui substrate, chlorofilo a sintezė žaliosios šerytės augaluose vyko intensyviau, lyginant su kontrole, tuo tarpu pirmą drėgmės deficito savaitę neturėjo esminės įtakos chlorofilo b ir karotenoidų kiekiams. Modeliuojant drėgmės deficitą substrate ilgiau nei savaitę chlorofilų a ir b bei karotenoidų kiekiai statistiškai patikimai mažėjo. Chlorofilų a ir b santykis statistiškai patikimai padidėjo jau po trijų drėgmės deficito dienų. Chlorofilų ir karotenoidų santykis žaliosios šerytės augaluose pradėjo mažėti po 5 sausros dienų. Ilginant sausros trukmę, santykinis vandens kiekis žaliosios šerytės augaluose, augintuose drėgmės deficito sąlygomis, nuosekliai mažėjo ir buvo esmingai mažesnis, lyginant su kontroliniais augalais. Drėgmės deficitas substrate esmingai mažino žaliosios masės kaupimąsi žaliosios šerytės augaluose. Pirmą sausros savaitę... [toliau žr. visą tekstą] / The objective of this study was to investigate the effect of moisture deficit on morphophysiological parameters of green millet plants. Object of the work – green millet (Setaria viridis (L.) P. Beauv.). Methods of the work: green millet plants were growing in growth chamber under 20/18 °C (day/night) temperature, 16/8 h (day/night) photoperiod, 50 µmol m-2 s-1 light intensity. Moisture deficit treatment was applied when plants were in organogenesis stage four. Amount of photosynthetic pigments, fresh mass of plants, dry weight and relative water content in plant leaves were investigated. The results of work. Relatively slight moisture deficit resulted in more intensive chlorophyll a synthesis in green millet plant in comparison with control, while first week of moisture deficit didn’t have any effect on chlorophyll b and carotenoids contents. For more than a week-long drought significantly inhibited the chlorophyll a and b contents as well as carotenoids content in green millet plants. The ratio of chlorophyll a and b significantly increased after three days of moisture deficit. The ratio of chlorophylls and carotenoids decreased after five drought days. Elongation of drought stress resulted in decreasing of relative water content in plant leaves. The fresh mass of plants significantly decreased under moisture deficit treatment. First week of drought stress resulted in increasing of dry weight, while under treatment of 9-18 days of drought treated plants accumulate... [to full text]
885

Suitability of Canadian-bred and Native Plant Species for Extensive Green Roofs in Northern Nova Scotia

Grant, Jason J W 20 February 2013 (has links)
Research was conducted to determine individual suitability of native and Canadian-bred selected plants in terms of growth and survivability for local extensive green roofs. The experiment was single-factor (species) with 12 levels (two Sedum spp. [controls]; 10 Canadian-bred or native plant species) in a randomized complete block design with three blocks. Variables measured were percent survival and cover, height, fresh and dry weights, stomatal conductance, transpiration, photosynthetic rate, soil temperature, soil moisture, and reflectance. Artemisia stelleriana contributed more to cooling through transpiration than Sedum floriferum, and maintained similar soil moisture to Sedum acre. Lotus corniculatus was similar to the controls in photosynthetic rate and had higher reflectance than Sedum acre in July. With high biomass and photosynthetic rates, Aster novi-belgii may contribute more to carbon sequestration and insulation than the controls. Artemisia stelleriana , Lotus corniculatus, and Aster novi-belgii are suitable species for extensive green roofs in northern Nova Scotia.
886

Mercury flux from naturally enriched bare soils during simulated seasonal cycling

Walters, Nicholas 06 September 2013 (has links)
Mercury (Hg) is a potent human toxin and a persistent global pollutant with unique properties and environmental behaviours which make it difficult to model and understand. While anthropogenic mercury sources are well understood along with the impacts on ecosystems and human populations, the processes and transformations which govern environmental cycling lack the same level of understanding. Concentrations in Arctic environments are a specific concern, along with cycling behaviours in regions spanning from temperate to Arctic climates. The objective of this experiment was the investigation and characterization of the mechanisms which promote elemental mercury (Hg^0) flux from soils in these environments during simulated seasonal cycling. A laboratory scale experiment was conducted which used a Dynamic Flux Chamber (DFC) to monitor Hg^0 flux from a naturally Hg enriched soil during temperature cycling relevant to cold environments. The results, which were split into freeze-thaw (FT) and sub-zero (SZ) cycles, showed that Hg^0 flux from frozen soils remains active during temperature cycling. During FT cycles, Hg^0 flux is controlled by soil temperature and energy entering the system, with a linear increase in flux for increases in energy. This response is produced from the entire soil column. During SZ cycles, Hg^0 flux is produced only in the thin soil surface layer and is controlled by the air temperature at the soil-air interface. A decrease in the DFC air temperature was observed to produce an increase in flux, with an inverse relationship controlled by a separate mechanism than the FT cycle response. Recommendations for modifications to the experimental set-up and methodology have been made to improve the accuracy of the results and confirm the behaviours characterized during this study. / Natural Sciences and Engineering Research Council of Canada (NSERC)
887

Ecological land classification and soil moisture modelling in the boreal forest using LiDAR remote sensing

SOUTHEE, FLORENCE MARGARET 20 December 2010 (has links)
Ecological land classification (ELC) is used to classify forest types in Ontario based on ecological gradients of soil moisture and nutrient fertility determined in the field. If ELC could be automated using terrain surfaces generated from airborne Light Detection and Ranging (LiDAR) remote sensing, it would enhance our ability to carry out forest ecosite classification and inventory over large areas. The focus of this thesis was to determine if LiDAR-derived terrain surfaces could be used to accurately quantify soil moisture in the boreal forest at a study site near Timmins, Ontario for use in ELC systems. Analysis was performed in three parts: (1) ecological land classification was applied to classify the forest plots based on soil texture, moisture regime and dominant vegetation; (2) terrain indices were generated at four different spatial resolutions and evaluated using regression techniques to determine which resolution best estimated soil moisture; and (3) ordination techniques were applied to separate the forest types based on biophysical field measurements of soil moisture and nutrient availability. The results of this research revealed that no single biophysical measurement alone could completely separate forest types; furthermore, the best LiDAR-derived terrain variables explained only 36.5% of the variation in the soil moisture in this study area. These conclusions suggest that species abundance data (i.e., indicator species) should be examined in tandem with biophysical field measurements and LiDAR data to improve classification accuracy. / Thesis (Master, Geography) -- Queen's University, 2010-12-16 18:52:04.81
888

Chemical-enhanced filtration of Cu/Ni concentrate

Zheng, Haijun Unknown Date
No description available.
889

Impact of Mountain Pine Beetle Attack on Water Balance of Lodgepole Pine Forests in Alberta

Pina Poujol, Pablo Cesar Unknown Date
No description available.
890

Nitrogen and moisture distributions under subirrigated soybeans

Papadopoulos, Anastasios K. January 1994 (has links)
A field lysimeter experiment was conducted on a sandy loam soil during the 1990 and 1991 growing seasons. The experiment tested the effects of different watertables on soybean yields, and on moisture distribution and nitrogen concentration of the soil profile. The watertable depths were 40, 60, 80, and 100 centimeters (cm). / Yields were measured in terms of number of beans per plant, number of pods per plant, number of beans per pod, and seed protein content at harvest. / Soil samples collected at depths of 30 and 70 cm from the soil surface were analyzed for moisture content and NO$ sb3 sp-$-N and NH$ sb4 sp+$-N concentrations. / The experimental results showed that controlled watertable management increased the yield and decreased soil NO$ sb3 sp-$-N levels. The best results from the watertables tested were found to be at 60 and 80 cm. This is suggested as the range of watertable depths that should be maintained for optimum soybean production.

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