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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.
1601

Moisture risks with CLT-panels subjected to outdoor climate during construction : focus on mould and wetting processes / Fuktrisker på KL-trä som utsätts för yttre klimat under produktion : fokus på mögel och uppfuktning

Öberg, Johan, Wiege, Erik January 2018 (has links)
When going through relevant research, moisture safety guidelines and talking to builders, moisture experts and architects it is clear - and not surprising - that water and wood make no easy combination. The experiences from building with cross laminated timber (CLT) differ from building sites and there are good and bad examples building without weather protection. In this study the moisture influence on CLT is analyzed. CLT is a type of massive wood with glued lamellas, increasing usage worldwide as structural elements in buildings. The bulk of the work is performed in the hygrothermal calculation tool WUFI(™). Focus is on the wetting process and the evaluation of mould risk from rain loads during production in Nordic climates. Subsequent drying after built into walls and floors is also evaluated. A vast literature survey is performed in order to compare and select material data for modelling CLT. Following the simulation work, moisture content, mould growth and volumetric distortion are judged both with and without weather protection. Results are also compared to measurement data from field tests. It is found that short building times are crucial, some weather protection is required all year around and early planning and constructing for moisture safety are crucial. The benefits of prefabrication and short building times using CLT should be exploited. If there is a risk of rainfall exceeding 10-20 mm, arrangements to divert rain loads should be undertaken. If the expected rain loads are above 40 mm or if the building time exceeds 2 weeks, a roof cover will be required. At air humidities averaging 80% and yearly rain exceeding 1200 mm, a complete building cover is recommended. A controlled environment may be expensive, but it speeds up production and shortens drying time. / När man går igenom relevant forskning, riktlinjer för fuktsäkerhet och pratar med byggare, fuktexperter och arkitekter är det tydligt - och inte överraskande - att vatten och trä inte är någon enkel kombination. Erfarenheterna från att bygga med korslimmat trä (KL-trä) skiljer sig från byggarbetsplatser och det finns bra och dåliga exempel från byggande utan väderskydd. I denna studie analyseras fuktpåverkan på KL-trä. KL-trä är en typ av massivt trä med limmade lameller, som ökar i användningen över hela världen som strukturella element i byggnader. Huvuddelen av arbetet utförs i det hygrotermiska beräkningsverktyget WUFI (™). Fokus ligger på uppfuktning och utvärdering av mögelrisker från regnbelastning under produktion i nordiskt klimat. Efterföljande torkning efter inbyggnad i väggar och golv utvärderas också. En omfattande litteraturstudie utförs för att jämföra och välja materialdata för modellering av KL-trä. Efter simuleringsarbetet bedöms fuktinnehåll, mögeltillväxt och fuktrörelser både med och utan väderskydd. Resultaten jämförs också med mätdata från fältförsök. Det konstateras att korta byggtider är avgörande, någon form av väderskydd krävs året runt och tidig planering och konstruktion för fuktsäkerhet är avgörande. Fördelarna med prefabricering och korta byggtider med KL-trä bör utnyttjas. Om det finns risk för nederbörd över 10-20 mm bör åtgärder vidtas för att avleda regn. Om de förväntade regnbelastningarna är över 40 mm eller om byggtiden överstiger 2 veckor krävs ett regnskydd. Vid luftfuktigheter på i medeltal 80 % och årligt regn över 1200 mm rekommenderas ett väderskydd runt hela byggnaden. En kontrollerad miljö kan vara dyr, men det påskyndar produktionen och förkortar torkningstiden.
1602

Underlag för projektering av terrasstak och källarväggar : Kvalitativ analys av terrasstak och källarväggar ur ett livslängdsperspektiv med fokus på byggbarhet, fuktsäkerhet, robusthet och kostnad / Basis for design of terraces and cellar walls : Qualitative analysis of terrace roofs and cellar walls from a lifetime perspective focusing on constructability, moisture safety, robustness and cost

Brodén, David, Wiik, Amanda January 2018 (has links)
Typdetaljer för olika byggnadsdelar som finns tillgängliga på internet och i böcker är idag begränsade i sin utformning. Terrasstak och källarväggar har båda en utmanande konstruktion där det ställs höga krav på utformning då de är husets skydd mot det yttre klimatet. Uppdragsgivaren WSP hade upplevt ett problem med att konstruktörer på företaget ritade olika vid projektering av dessa typer av detaljer. Företaget ville därför hitta en metod där konstruktörerna kunde utgå från samma typdetaljer. Syftet med detta arbete var att underlätta kvalitetssäkringen av konstruktionsdetaljer vid projektering av terrasstak och källarväggar genom att skapa ett underlag att utgå ifrån. Målet blev då att framställa tydliga typdetaljer med tillhörande teknisk beskrivning. Genom litteraturstudier, projektgranskningar, samtal med konstruktörer och experter på och utanför företaget har underlag insamlats. Ett underlag som sedan legat till grund för analys och slutsats. Analys och slutsats genomfördes utifrån ett livslängdsperspektiv med fokus på aspekterna; byggbarhet, fuktsäkerhet, robusthet och kostnad. Resultatet visade tydligt att konstruktörerna ritat dessa detaljer olika och att de inte alltid har kunnat motivera sina val. Resultatet visade också att gällande terrasstak är det omvända konceptet det bästa ur livslängdssynpunkt och för källarväggar är det viktigt att väggen hålls varm och torr. För både källarväggar och terrasstak råder flera olika förutsättningar som påverkat framtagningen av typdetaljer. Slutligen resulterade arbetet i två typdetaljer för terrasstak och tre för källarväggar. / Construction details available on the Internet and in books for various building components are today limited in their design. Terraces and cellar walls both have a challenging construction where high demands are made, as they are the house's protection against the external climate.   The initiator WSP had experienced a problem that designers at the company designed differently when designing these types of details. The company therefore wanted to find a method where the designers could use the same type details as guidance.   The purpose of this work was to facilitate the quality assurance of design details when designing terrace roofs and cellar walls by creating a basis for starting. The goal was then to produce clear construction details with an accompanying technical description.   Through literature studies, project reviews, conversations with designers and experts on and outside the company, information has been collected to a sufficient extent as a basis for analysis and conclusion. Analysis and conclusion were conducted based on a longevity perspective focusing on the aspects; constructability, moisture safety, robustness and cost. The result clearly showed that the designers at the office designed these details differently and that they could not always justify their choices. The result also showed that the terrace roof as per the reverse concept is the best solution according to the longevity perspective, and for cellar walls is the important aspects to keep the wall dry and warm. For both cellar walls and terraces, there are different conditions that affect the production of construction details. This eventually led to two types construction details of terrace roofs and three for cellar walls.
1603

Biogeochemical Cycling And Nutrient Control Strategies For Groundwater At Stormwater Infiltration Basins

O'Reilly, Andrew M 01 January 2012 (has links)
Elevated concentrations of nutrients, particularly nitrate, in groundwater and springs in Florida are a growing resource management concern. Stormwater infiltration basins, which are a common stormwater management practice in the well-drained karst terrain areas of Florida, are a potentially important source of nutrients to the groundwater system because stormwater exits the basin by only evaporation or infiltration. To better understand the biogeochemical processes integrating stormwater infiltration impacts on groundwater resources in a field-scale setting, a combination of hydrologic, soil chemistry, water chemistry, dissolved and soil gas, isotope, and microbiological data was collected from 2007 through 2010 at two stormwater infiltration basins receiving runoff from predominantly residential watersheds in north-central Florida. Substantially different biogeochemical processes affecting nitrogen fate and transport were observed beneath the two stormwater infiltration basins. Differences are related to soil textural properties that deeply link hydroclimatic conditions with soil moisture variations in a humid, subtropical climate. During 2008, shallow groundwater beneath the basin with predominantly clayey soils (median 41% silt+clay content) exhibited decreases in dissolved oxygen from 3.8 to 0.1 mg/L and decreases in nitrate-nitrogen from 2.7 mg/L to less than 0.016 mg/L, followed by manganese and iron reduction, sulfate reduction, and methanogenesis. In contrast, beneath the basin with predominantly sandy soils (median 2% silt+clay content), aerobic conditions persisted from 2007 through 2009 (dissolved oxygen of 5.0â€"7.8 mg/L), resulting in nitrate-nitrogen of 1.3â€"3.3 mg/L in shallow groundwater. Soil extractable nitrate-nitrogen was significantly lower and the copper-containing nitrite reductase gene density was significantly higher beneath the clayey basin. Differences in moisture retention capacity between fine- and coarse-textured soils resulted in median volumetric gas-phase contents of 0.04 beneath the clayey basin and 0.19 beneath the sandy basin, inhibiting surface/subsurface oxygen exchange beneath the clayey basin. Subsurface biogeochemical processes at the clayey stormwater infiltration basin were further analyzed to better understand the effects of the highly variable hydrologic conditions common in humid, subtropical climates. Cyclic variations in biogeochemical processes generally coincided with wet and dry hydroclimatic conditions. Oxidizing conditions in the subsurface persisted for about one month or less at the beginning of wet periods with dissolved oxygen and nitrate showing similar temporal patterns. Reducing conditions in the subsurface evolved during prolonged flooding of the basin. At about the same time oxygen and nitrate reduction concluded, manganese, iron, and sulfate reduction began, with the onset of methanogenesis one month later. Reducing conditions persisted up to six months, continuing into subsequent dry periods until the next major oxidizing infiltration event. Evidence of denitrification in shallow groundwater at the site is supported by median nitrate-nitrogen less than 0.016 mg/L, excess nitrogen gas up to 3 mg/L progressively enriched in delta-15N during prolonged basin flooding, and isotopically heavy delta-15N and delta-18O of nitrate (up to 25 and 15 per mil, respectively). Isotopic enrichment of newly infiltrated stormwater suggests denitrification was partially completed within two days. Soil and water chemistry data suggest a biogeochemically active zone exists in the upper 1.4 m of soil, where organic carbon was the likely electron donor supplied by organic matter in soil solids or dissolved in infiltrating stormwater. The cyclic nature of reducing conditions effectively controlled the nitrogen cycle, switching nitrogen fate beneath the basin from nitrate leaching to reduction in the shallow saturated zone. Soil beneath the sandy stormwater infiltration basin was amended using biosorption activated media (BAM) to study the effectiveness of this technology in reducing inputs of nitrogen and phosphorus to groundwater. The functionalized soil amendment BAM consists of a 1.0:1.9:4.1 mixture (by volume) of tire crumb (to increase sorption capacity), silt and clay (to increase soil moisture retention), and sand (to promote sufficient infiltration), which was applied to develop an innovative best management practice (BMP) utilizing nutrient reduction and flood control sub-basins. Construction and materials costs, excluding profit and permit fees, for the innovative BMP were about $US 65 per square meter of basin bottom. Comparison of nitrate/chloride ratios for the shallow groundwater indicate that prior to using BAM, nitrate concentrations were substantially influenced by nitrification or variations in nitrate input. In contrast, for the new basin utilizing BAM, nitrate/chloride ratios indicate minor nitrification and nitrate losses with the exception of one summer sample that indicated a 45% loss. Biogeochemical indicators (denitrifier activity derived from real-time polymerase chain reaction and variations in major ions, nutrients, dissolved and soil gases, and stable isotopes) suggest nitrate losses are primarily attributable to denitrification, whereas dissimilatory nitrate reduction to ammonium and plant uptake are minor processes. Denitrification was likely occurring intermittently in anoxic microsites in the unsaturated zone, which was enhanced by increased soil moisture within the BAM layer and resultant reductions in surface/subsurface oxygen exchange that produced conditions conducive to increased denitrifier activity. Concentrations of total dissolved phosphorus and orthophosphate were reduced by more than 70% in unsaturated zone soil water, with the largest decreases in the BAM layer where sorption was the most likely mechanism for removal. Post-BAM orthophosphate/chloride ratios for shallow groundwater indicate predominantly minor increases and decreases in orthophosphate with the exception of one summer sample that indicated a 50% loss. Differences in nutrient variations between the unsaturated zone and shallow groundwater may be the result of the intensity and duration of nutrient removal processes and mixing ratios with water that had undergone little biogeochemical transformation. In order to quantify potential processes leading to observed nitrogen losses beneath the innovative BMP, an integrated infiltration basinâ€"nitrogen reduction (IBNR) system dynamics model was developed. Based on two simulation periods, the IBNR model indicated denitrification accounted for a loss of about one-third of the total dissolved nitrogen mass inflow and was occurring predominantly in the BAM layer. The IBNR model results in combination with the field-based biogeochemical assessment demonstrated that the innovative BMP using the functionalized soil amendment BAM is a promising passive, economical, stormwater nutrient-treatment technology. Further field- and laboratory-scale research on the long-term sustainability of nutrient losses and further elucidation of causative physicochemical and biogeochemical mechanisms would contribute to improved BAM performance and green infrastructure development in the future.
1604

Chemical emissions from building structures : emission sources and their impact on indoor air / Kemiska emissioner från byggnadskonstruktioner : källor till emissioner och deras påverkan på inomhusluften

Glader, Annika January 2012 (has links)
Chemical compounds in indoor air can adversely affect our comfort and health. However, in most cases there is only a limited amount of information available that can be used to assess their health risk. Instead the precautionary principle is often applied, i.e. efforts are made to ensure that the concentrations of pollutants are kept at a minimum when constructing new buildings or conducting renovations by using low-emitting building materials. Today, when investigating buildings in order to solve indoor air quality problems, volatile organic compounds (VOCs) are sampled in the air within rooms. The chemical composition of indoor air is complex and there are many sources for the chemicals present. The potential for emissions from sources in hidden spaces such as wall cavities is poorly understood and little information exists on the toxic potential of chemical releases resulting from moisture-related degradation of building materials. Most of the non-reactive VOCs that have been detected in indoor air in field studies and from building products are not believed to cause health problems. However, reactive compounds and chemical reaction products have the potential to negatively influence our comfort and health even at low concentrations. Even though the impact of chemical compounds on health is unclear in many cases, they can be used to identify technical problems in buildings. When a building is investigated, the air inside building structures could be sampled. This method would eliminate emissions from sources other than the construction materials and the samples would contain higher levels of individual compounds. The aims of this work was to identify emissions profiles for different types of building structures, to see if the emission profiles for moisture damaged and undamaged structures differed, and to determine whether any of the emissions profiles for specific structures also could be found in indoor air. Technical investigations and VOC sampling were performed in 21 different buildings with and without previous moisture damage. Seven of the buildings were investigated in the years 2005-2006 (study 1) and fourteen in the years 2009-2010 (study 2). In study 1, sixty samples were analyzed by PCA at the chemical group level (18 chemical groups, i.e. aldehydes, ketones etc). 41 % of all identified chemical compounds belonged to the hydrocarbon chemical group. The second largest chemical groups, each of which accounted for 5-10 % of all identified compounds, were alcohols, aldehydes, ketones, polyaromatic hydrocarbons (PAHs) and terpenes. The results indicated that one of the main factors that determined the emissions profile of a building structure was the materials used in its construction. Notably, concrete and wooden structures were found to have different emissions profiles. The sum of VOC (TVOC) concentrations for all 241 samples from both study 1 and study 2 was used to compare total emissions between different building elements (ground and higher floors, external walls and roof spaces). Most building elements exhibited relatively low emissions compared to concrete ground floors, which generally had higher TVOC emissions. Emissions from both polystyrene insulation and PVC flooring could be identified in concrete ground floors and were the main cause for the higher emissions found in these structures. Profiles for wood preservatives such as creosote and pentachlorophenol were also identified in external walls. The emission profiles found in the structures could not be identified in the indoor air in the adjacent rooms, although individual compounds were sometimes detected at low concentrations. Our results showed that the main factors influencing emissions in building structures were the construction materials and the nature of the building element in question. Because of difficulties with finding active water damage at the times of sampling and because of sampling inside closed building structures with old dried-out moisture damages, the field method used in this work was unsuitable for identifying differences in emission profiles between moisture damaged and undamaged structures. It will thus be necessary to investigate this difference in a laboratory where the precise composition of all tested structures is known, a range of RH values can be tested and the accumulation of emissions can be followed. / Kompetenscentrum Byggnad - Luftkvalitet - Hälsa 2 (KLUCK 2)
1605

Lagerung von Pappelrundholz aus Kurzumtriebsplantagen – Evaluierung verschiedener Lagerungsverfahren unter besonderer Berücksichtigung der Holzfeuchte als möglicher Parameter einer automatisierten Qualitätsüberwachung

Starke, Nicole 25 January 2023 (has links)
Vor dem Hintergrund einer angestrebten stofflichen Nutzung von Pappelholz aus Kurzumtriebsplantagen (KUP) zur Herstellung von Holzwerkstoffen und des eingeschränkten Erntezeitpunktes der Pappeln in den Wintermonaten ergab sich die Frage, wie das Holz über einen Lagerungszeitraum von bis zu neun Monaten bei gleichzeitiger Erhaltung der Holzqualität gelagert werden kann. Zu diesem Zweck wurden verschiedene Lagerungsverfahren getestet: Trockenlagerung mit und ohne Rinde, Beregnung mit und ohne Rinde, Folienlagerung mit und ohne Rinde sowie einem aus Beregnung und Trockenlagerung kombinierten Verfahren. Insgesamt wurden 105 Raummeter Pappelrundholz aus KUP in zwei verschiedenen Lagerungsperioden 2018 und 2019 eingelagert. Die Holzqualität des gelagerten Pappelholzes wurde anhand von Untersuchungen zur Veränderung der Darrdichte, der chemischen Zusammensetzung (Cellulose-, Hemicellulosen-, Lignin-, Extraktstoffanteil) und ergänzend durch mikroskopische Untersuchungen bewertet. Ein weiterer Fokus lag auf der Holzfeuchte zur Abschätzung der Gefahr eines Pilzbefalls. Die Ergebnisse zeigten, dass es bei der Trockenlagerung mit Rinde in der Lagerungsperiode 2019 durch einen festgestellten Befall durch holzzerstörende Pilze, einer Reduktion der Darrdichte von 11 % sowie starken Änderungen der chemischen Zusammensetzung (vor allem Reduktion der Holzpolyosen) zu den stärksten Veränderungen kam. Bei der Trockenlagerung ohne Rinde waren die beobachteten Veränderungen deutlich geringer (maximale Abnahme der Darrdichte 3 %). Bei den beiden Lagerungsverfahren Beregnung und Folienlagerung konnte eine Lagerung des Holzes in einem für holzzerstörende Pilze unkritischen Holzfeuchtebereich nachgewiesen werden. Ein Befall durch holzzerstörende Pilze wurde durch die mikroskopischen Untersuchungen nicht festgestellt. Bei der Beregnung fiel die Veränderung der Darrdichte bei einigen Varianten stärker aus als erwartet. Für eine abschließende Bewertung sind weitere Untersuchungen notwendig. Der Klon Max 1 zeigte oft stärkere Veränderungen als der Klon AF2. Auch hier sind weitere Untersuchungen notwendig. Aus den Ergebnissen wurde geschlussfolgert, dass die Holzqualität mittels Folienlagerung am besten erhalten werden konnte. Auch die Trockenlagerung ohne Rinde wird aufgrund der geringen festgestellten Veränderungen und im Hinblick auf die geringen Kosten als geeignet erachtet. Es muss jedoch beachtet werden, dass dieses Lagerungsverfahren stark witterungsabhängig ist.:Kurzfassung Abstract Abbildungsverzeichnis Tabellenverzeichnis Abkürzungsverzeichnis 1 Einleitung 1.1 Hintergrund 1.2 Ziele und Thesen 1.3 Aufgabenstellung 2 Stand von Wissenschaft und Technik 2.1 Die Pappel und ihr Holz 2.1.1 Die Baumart Pappel 2.1.2 Die Holzart Pappel 2.1.3 Verwendung von Pappelholz 2.2 Kurzumtriebsplantagen (KUP) 2.2.1 Allgemein 2.2.2 Pappel auf Kurzumtriebsplantagen 2.2.3 Verwendung von Pappelholz aus KUP 2.3 Rundholzlagerung 2.3.1 Anwendungsgebiete und Ziele der Rundholzlagerung 2.3.2 Einflussfaktoren auf den Lagerungserfolg 2.3.3 Verfahren der Rundholzlagerung 2.3.3.1 Übersicht über die Lagerungsverfahren 2.3.3.2 Trockenlagerung 2.3.3.3 Nasslagerung 2.3.3.4 Folienlagerung 2.3.4 Risiken für die Rundholzlagerung 2.3.4.1 Einleitung 2.3.4.2 Biotische Risiken 2.3.4.3 Abiotische Risiken 2.3.5 Lagerung von Pappelrundholz aus Kurzumtriebsplantagen 2.4 Holzfeuchtebestimmung und Holzfeuchtemonitoring durch elektrische Widerstands-messung 2.4.1 Überblick Verfahren zur Bestimmung der Holzfeuchte 2.4.2 Elektrische Widerstandsmessung 2.4.2.1 Prinzip 2.4.2.2 Kalibrierfunktionen 2.4.3 Monitoring durch elektrische Widerstandsmessung 3 Material und Methoden 3.1 Material 3.1.1 Eingesetztes Versuchsmaterial für die Lagerungsperiode 2018 3.1.2 Eingesetztes Versuchsmaterial für die Lagerungsperiode 2019 3.2 Methoden 3.2.1 Überblick Methoden 3.2.2 Versuchsaufbau 3.2.2.1 Lagerungsperiode 2018 3.2.2.2 Lagerungsperiode 2019 3.2.3 Untersuchungen 3.2.3.1 Überblick Untersuchungen und Beprobungsstrategie 3.2.3.2 Holzfeuchte 3.2.3.3 Darrdichte 3.2.3.4 Chemische Analysen 3.2.3.5 Pilz- und Bakterienbefall 3.2.3.6 Triebbildung 3.2.3.7 Gasanalyse 3.2.3.8 Elektrische Widerstandsmessung zur Ermittlung der Holzfeuchte 3.2.4 Dokumentation von Witterungsdaten 3.2.5 Statistische Auswertung 4 Ergebnisse 4.1 Systematik der Ergebnisdarstellung 4.2 Witterungsdaten 4.2.1 Lagerungsperiode 2018 4.2.2 Lagerungsperiode 2019 4.3 Gasatmosphäre 4.4 Holzfeuchte 4.4.1 Lagerungsperiode 2018 4.4.2 Lagerungsperiode 2019 4.5 Darrdichte 4.5.1 Lagerungsperiode 2018 4.5.2 Lagerungsperiode 2019 4.6 Chemische Zusammensetzung 4.6.1 Lagerungsperiode 2018 4.6.2 Lagerungsperiode 2019 4.7 Pilz- und Bakterienbefall 4.7.1 Lagerungsperiode 2018 4.7.2 Lagerungsperiode 2019 4.8 Triebbildung 4.8.1 Lagerungsperiode 2018 4.8.2 Lagerungsperiode 2019 4.9 Sonstige Beobachtungen 4.9.1 Rissbildungen bei der Trockenlagerung 4.9.2 Mäuse und einwachsende Pflanzenteile 4.10 Monitoring der Holzfeuchteentwicklung im Laufe der Lagerungsperiode 2019 4.10.1 Erstellung der Kalibrierfunktion für Pappelholz 4.10.1.1 Modell 1 4.10.1.2 Modell 2 4.10.2 Anwendung der ermittelten Kalibrierfunktion auf die mittels Datenlogger aufgezeichneten Messwerte im Zuge der Lagerungsperiode 2019 5 Diskussion 5.1 Evaluierung der Lagerungsverfahren unter Berücksichtigung der Holzfeuchte 5.1.1 Erwartete Holzqualität der einzelnen Lagerungsvarianten aufgrund der festgestellten Holzfeuchte 5.1.2 Trockenlagerung 5.1.2.1 Holzfeuchte und Witterungsbedingungen 5.1.2.2 Veränderung der Darrdichte und der chemischen Zusammensetzung, Pilzbefall 5.1.2.3 Zusammenfassende Einschätzung zur Trockenlagerung 5.1.3 Beregnung 5.1.3.1 Holzfeuchte 5.1.3.2 Veränderung der Darrdichte und der chemischen Zusammensetzung, Pilz- und Bakterienbefall 5.1.3.3 Zusammenfassende Einschätzung zur Beregnung 5.1.4 Kombiniertes Verfahren aus Beregnung und Trockenlagerung 5.1.4.1 Holzfeuchte und Witterungsbedingungen 5.1.4.2 Veränderung der Darrdichte und der chemischen Zusammensetzung, Pilz- und Bakterienbefall 5.1.4.3 Zusammenfassende Einschätzung zum kombinierten Verfahren 5.1.5 Folienlagerung 5.1.5.1 Gasanalyse in den Folienpaketen 5.1.5.2 Holzfeuchte 5.1.5.3 Veränderung der Darrdichte und der chemischen Zusammensetzung, Pilz- und Bakterienbefall 5.1.5.4 Zusammenfassende Einschätzung zur Folienlagerung 5.1.6 Vergleich der Klone Max 1 und AF2 5.1.7 Zusammenfassung und Bewertung der Lagerungsvarianten 5.2 Monitoring der Holzfeuchteentwicklung im Laufe der Lagerungsperiode durch elektrische Widerstandsmessung 5.2.1.1 Kalibierfunktion für Pappelholz aus KUP 5.2.1.2 Einsatzmöglichkeit der elektrischen Widerstandsmessung zur Qualitätsüberwachung von Pappelrundholzpoltern 6 Schlussfolgerung 7 Zusammenfassung 8 Ausblick Literaturverzeichnis / Considering the desired material use of poplar wood from short-rotation coppices (SRC) for the production of wooden materials and the limited harvest season, the question arose how the wood should be stored over a period of up to nine months while preserving the wood quality (at the same time). For this purpose, different storage methods were tested: storage in compact piles with and without bark, storage with water sprinkling with and without bark and storage under oxygen exclusion with and without bark, as well as storage in compact pile with temporary water sprinkling as a combined storage method. A total amount of 105 cubic meters test piles with poplar logs from SRC were set up in two different storage periods, 2018 and 2019. The clones Max 1 and AF2 were evaluated using 18 different storage variants. The quality of the stored poplar wood was evaluated based on changes in the wood density ρ0, chemical composition (cellulose, hemicelluloses, lignin and extract content) complemented by microscopic examinations. A further focus was the wood moisture content evaluation to estimate the potential risk of fungal decay. The results demonstrated that storage in compact piles in the storage period of 2019 resulted in the biggest changes caused by an infestation of wood-destroying fungi, 11.1% reduction of the wood density ρ0, and significant changes of chemical composition, in particular reduction of wood polyoses. Storage in compact piles without bark showed substantially lower changes (maximum decrease of wood density ρ0 of 3.3%). For storage with water sprinkling and storage under oxygen exclusion it could be shown that both result in storage conditions with an uncritical wood moisture range in relation to wood-destroying fungi (fungi decay). Fungi decay could not be observed by microscopic examination. Additional studies are required for a final assessment. Clone Max 1 showed frequently stronger changes than clone AF2. Further investigation is needed here as well. Based on the results it can be concluded that the wood quality could be preserved best by using the storage under oxygen exclusion. Storage in compact piles without bark can be considered as suitable as well due to the minor changes and considering the low costs. However, it has to be taken into account hat this storage method is very climate-dependent.:Kurzfassung Abstract Abbildungsverzeichnis Tabellenverzeichnis Abkürzungsverzeichnis 1 Einleitung 1.1 Hintergrund 1.2 Ziele und Thesen 1.3 Aufgabenstellung 2 Stand von Wissenschaft und Technik 2.1 Die Pappel und ihr Holz 2.1.1 Die Baumart Pappel 2.1.2 Die Holzart Pappel 2.1.3 Verwendung von Pappelholz 2.2 Kurzumtriebsplantagen (KUP) 2.2.1 Allgemein 2.2.2 Pappel auf Kurzumtriebsplantagen 2.2.3 Verwendung von Pappelholz aus KUP 2.3 Rundholzlagerung 2.3.1 Anwendungsgebiete und Ziele der Rundholzlagerung 2.3.2 Einflussfaktoren auf den Lagerungserfolg 2.3.3 Verfahren der Rundholzlagerung 2.3.3.1 Übersicht über die Lagerungsverfahren 2.3.3.2 Trockenlagerung 2.3.3.3 Nasslagerung 2.3.3.4 Folienlagerung 2.3.4 Risiken für die Rundholzlagerung 2.3.4.1 Einleitung 2.3.4.2 Biotische Risiken 2.3.4.3 Abiotische Risiken 2.3.5 Lagerung von Pappelrundholz aus Kurzumtriebsplantagen 2.4 Holzfeuchtebestimmung und Holzfeuchtemonitoring durch elektrische Widerstands-messung 2.4.1 Überblick Verfahren zur Bestimmung der Holzfeuchte 2.4.2 Elektrische Widerstandsmessung 2.4.2.1 Prinzip 2.4.2.2 Kalibrierfunktionen 2.4.3 Monitoring durch elektrische Widerstandsmessung 3 Material und Methoden 3.1 Material 3.1.1 Eingesetztes Versuchsmaterial für die Lagerungsperiode 2018 3.1.2 Eingesetztes Versuchsmaterial für die Lagerungsperiode 2019 3.2 Methoden 3.2.1 Überblick Methoden 3.2.2 Versuchsaufbau 3.2.2.1 Lagerungsperiode 2018 3.2.2.2 Lagerungsperiode 2019 3.2.3 Untersuchungen 3.2.3.1 Überblick Untersuchungen und Beprobungsstrategie 3.2.3.2 Holzfeuchte 3.2.3.3 Darrdichte 3.2.3.4 Chemische Analysen 3.2.3.5 Pilz- und Bakterienbefall 3.2.3.6 Triebbildung 3.2.3.7 Gasanalyse 3.2.3.8 Elektrische Widerstandsmessung zur Ermittlung der Holzfeuchte 3.2.4 Dokumentation von Witterungsdaten 3.2.5 Statistische Auswertung 4 Ergebnisse 4.1 Systematik der Ergebnisdarstellung 4.2 Witterungsdaten 4.2.1 Lagerungsperiode 2018 4.2.2 Lagerungsperiode 2019 4.3 Gasatmosphäre 4.4 Holzfeuchte 4.4.1 Lagerungsperiode 2018 4.4.2 Lagerungsperiode 2019 4.5 Darrdichte 4.5.1 Lagerungsperiode 2018 4.5.2 Lagerungsperiode 2019 4.6 Chemische Zusammensetzung 4.6.1 Lagerungsperiode 2018 4.6.2 Lagerungsperiode 2019 4.7 Pilz- und Bakterienbefall 4.7.1 Lagerungsperiode 2018 4.7.2 Lagerungsperiode 2019 4.8 Triebbildung 4.8.1 Lagerungsperiode 2018 4.8.2 Lagerungsperiode 2019 4.9 Sonstige Beobachtungen 4.9.1 Rissbildungen bei der Trockenlagerung 4.9.2 Mäuse und einwachsende Pflanzenteile 4.10 Monitoring der Holzfeuchteentwicklung im Laufe der Lagerungsperiode 2019 4.10.1 Erstellung der Kalibrierfunktion für Pappelholz 4.10.1.1 Modell 1 4.10.1.2 Modell 2 4.10.2 Anwendung der ermittelten Kalibrierfunktion auf die mittels Datenlogger aufgezeichneten Messwerte im Zuge der Lagerungsperiode 2019 5 Diskussion 5.1 Evaluierung der Lagerungsverfahren unter Berücksichtigung der Holzfeuchte 5.1.1 Erwartete Holzqualität der einzelnen Lagerungsvarianten aufgrund der festgestellten Holzfeuchte 5.1.2 Trockenlagerung 5.1.2.1 Holzfeuchte und Witterungsbedingungen 5.1.2.2 Veränderung der Darrdichte und der chemischen Zusammensetzung, Pilzbefall 5.1.2.3 Zusammenfassende Einschätzung zur Trockenlagerung 5.1.3 Beregnung 5.1.3.1 Holzfeuchte 5.1.3.2 Veränderung der Darrdichte und der chemischen Zusammensetzung, Pilz- und Bakterienbefall 5.1.3.3 Zusammenfassende Einschätzung zur Beregnung 5.1.4 Kombiniertes Verfahren aus Beregnung und Trockenlagerung 5.1.4.1 Holzfeuchte und Witterungsbedingungen 5.1.4.2 Veränderung der Darrdichte und der chemischen Zusammensetzung, Pilz- und Bakterienbefall 5.1.4.3 Zusammenfassende Einschätzung zum kombinierten Verfahren 5.1.5 Folienlagerung 5.1.5.1 Gasanalyse in den Folienpaketen 5.1.5.2 Holzfeuchte 5.1.5.3 Veränderung der Darrdichte und der chemischen Zusammensetzung, Pilz- und Bakterienbefall 5.1.5.4 Zusammenfassende Einschätzung zur Folienlagerung 5.1.6 Vergleich der Klone Max 1 und AF2 5.1.7 Zusammenfassung und Bewertung der Lagerungsvarianten 5.2 Monitoring der Holzfeuchteentwicklung im Laufe der Lagerungsperiode durch elektrische Widerstandsmessung 5.2.1.1 Kalibierfunktion für Pappelholz aus KUP 5.2.1.2 Einsatzmöglichkeit der elektrischen Widerstandsmessung zur Qualitätsüberwachung von Pappelrundholzpoltern 6 Schlussfolgerung 7 Zusammenfassung 8 Ausblick Literaturverzeichnis
1606

Fukt- och värmeväxlare för vinteratleter : Ny konstruktion från problem till prototyp

Dale, Erica, Winberg, Rebecka January 2023 (has links)
Vid idrott utomhus i minusgrader utsätts andningssystemet för stora påfrestningar, luften är kall och torr vilket skadar och irriterar luftvägarna. För att undvika det kan man använda fukt- och värmeväxlare (HME). Dagens produkter har dålig passform vilket leder till läckage av luft. Syftet med projektet är att fler vinteratleter ska vilja använda HME och därmed förebygga förekomsten av andningssjukdomar. De tre delmålen för projektet är att tillverka minst en prototyp, den tillverkade prototypen ska ha bättre passform än dagens produkter och minst en lösning för slemhantering ska presenteras. Med hjälp av litteraturstudier lades en kunskapsgrund inom området. Verktyg som branschanalys, intressentanalys och målspecifikation gjorde konceptgenereringen rikare. Största delen av projektet lades i prototyptillverkning. Två prototyper kunde till slut presenteras, Winterflow och Winterflow Pro. Det är två additivt tillverkade masker med tillhörande filter som konstruerats i ett datormodelleringsprogram. Prototyperna validerades med hjälp av användartester. Prototyperna upplevs för en del testpersoner ha bättre passform än dagens produkter, men ingen statistisk signifikant skillnad gick att bevisa. Målen och syftet uppfylldes delvis och en bredare grund för vidare forskning fastställdes. / When performing sports outdoors during sub-zero conditions the respiratory system is exposed to great stress, the air is cold and dry, which damages and irritates the airways. To avoid this, the athletes can use heat and moisture exchanging devices (HME). Today’s products have a poor fit, which leads to leakage of the air. The aim of the project is to increase the usage of HME for winter athletes and thereby prevent the occurrence of respiratory diseases. The three objectives for the project are to manufacture at least one prototype, the prototype shall have a better fit than today’s products and at least one solution for handling saliva matter shall be presented. By carrying out literature studies, a foundation of knowledge was laid in the area. With the help of different analysis and tools, the concept generation were richer, resulting in more solutions. The main part of the project was put into prototyping. Two prototypes could be presented at the end, Winterflow and Winterflow Pro. Two additive manufactured masks with associated filters constructed in a computer modelling program. The prototypes were validated by user tests. The prototypes were perceived by some testers to have a better fit than today’s products, but no statistically significance could be proven. The aim and objectives were partly met, and a broader foundation of knowledge for further research was established. / <p>Betygsdatum 2023-06-07</p>
1607

Monitoring Water and Energy Cycles at Climate Scale in the Third Pole Environment (CLIMATE-TPE)

Su, Zhongbo, Ma, Yaoming, Chen, Xuelong, Peng, Xiaohua, Du, Junping, Han, Cunbo, He, Yanbo, Hofste, Jan G., Li, Maoshan, Li, Mengna, Lv, Shaoning, Ma, Weiqiang, Polo, María J., Peng, Jian, Qian, Hui, Sobrino, Jose, van der Velde, Rogier, Wen, Jun, Wang, Binbin, Wang, Xin, Yu, Lianyu, Zhang, Pei, Zhao, Hong, Zheng, Han, Zheng, Donghai, Zhong, Lei, Zeng, Yijian 08 May 2023 (has links)
A better understanding of the water and energy cycles at climate scale in the Third Pole Environment is essential for assessing and understanding the causes of changes in the cryosphere and hydrosphere in relation to changes of plateau atmosphere in the Asian monsoon system and for predicting the possible changes in water resources in South and East Asia. This paper reports the following results: (1) A platform of in situ observation stations is briefly described for quantifying the interactions in hydrosphere-pedosphere-atmosphere-cryosphere-biosphere over the Tibetan Plateau. (2) A multiyear in situ L-Band microwave radiometry of land surface processes is used to develop a new microwave radiative transfer modeling system. This new system improves the modeling of brightness temperature in both horizontal and vertical polarization. (3) A multiyear (2001–2018) monthly terrestrial actual evapotranspiration and its spatial distribution on the Tibetan Plateau is generated using the surface energy balance system (SEBS) forced by a combination of meteorological and satellite data. (4) A comparison of four large scale soil moisture products to in situ measurements is presented. (5) The trajectory of water vapor transport in the canyon area of Southeast Tibet in different seasons is analyzed, and (6) the vertical water vapor exchange between the upper troposphere and the lower stratosphere in different seasons is presented.
1608

Adaptiv styrning avtvärcirkulerande kanaltork : Analys och förutsättningar för adaptivfuktkvotsberäkning och justering av torktid / Adaptive Control of Cross CirculatingContinuous Kiln dryer : Analysis and conditions for adaptive control of crosscirculating continuous dryer

Backlund, Gustav January 2023 (has links)
För att minska energiförbrukningen och höja kapaciteten vid virkestorkning kan adaptiv styrning användas. Adaptiv styrning är en typ av processåterkoppling som visar på hur torkningen fortskrider och kan användas för att styra torkprocessen optimalt. Adaptiv styrning har funnits till kammartorkar länge. Tvärcirkulerande kanaltorkar (TC) liknar kammartorkar och man vill nu införa adaptiv styrning på dem. Syftet med studien var att analysera förutsättningarna för att tillämpa adaptiv styrning i TC-torken. En fältstudie genomfördes där funktionen adaptiv fuktkvotsberäkning som används som styrvariabel vid adaptiv styrning kontrollerades. Klimatmätningar under torkning genomfördes för att kontrollera om temperaturgivarna ger en bra bild av klimatet vid torksatsen.  Resultatet visar att funktionen adaptiv fuktkvotsberäkning stämmer överens för start- och slutfuktkvot i TC-torken. Funktionen fungerade något sämre på satser som innehöll virke med blandade dimensioner. Klimatmätningarna visar att temperaturgivarna återskapar klimatet vid virkessatsen på ett korrekt vis. Simuleringar visar att virket idag övertorkas och att en viss förkortning av torktiden hade varit möjlig. Det finns goda förutsättningar för att tillämpa adaptiv styrning i TC-torken
1609

Marktäckets och markfuktighetens påverkan på blomsterlupinens (Lupinus polyphyllus) utbredning i Jämtland / The influence of land cover and soil moisture on the distribution of garden lupine (Lupinus polyphyllus) in Jämtland

Svedh, Julia January 2024 (has links)
Biodiversity is the prerequisite for well-functioning ecosystem services that are crucial, like clean water and clean air. Invasive alien species (IAS) are a serious and long-term issue that is actively threatening the genetic diversity within ecosystems. In Sweden, 20 percent of 2000 alien species is estimated to be invasive or potentially invasive. One of the species that is assessed to be an IAS is garden lupine (Lupinus polyphyllus), which today is widely spread over big parts of Europe and it is established and reproducing in Sweden. The aim of the study was to find out wether the occurence of garden lupine in Jämtland (last 30 years) has an association with a certain type of land cover and soil moisture, and wether reported findings have increased over the years. This analysis was carried out by first statistically testing the association between the number of lupine observations and the reporting year. After that, a 5m-radius buffer was created around the reported species observations, to then compare the area of each class from National Land Cover Database (NMD) and SLU Soil Moisture Map within the buffer against the total area for each class within Jämtland County. The results of the study showed that the occurence of garden lupine can be associated with the type of land cover and soil moisture that is found on the place of occurence, and that the reports of occurence has increased over the years. The area of the land cover classes within the buffer was not proportional to the total area of those classes in Jämtland County. Lupine occured most commonly within land cover classes exploited land (50%; mainly "exploited land road/railway"), forest (30%), and other open land (20%). As for soil moisture, the garden lupine was only observed within two classes, and the area for these classes within the buffer was not proportional to the area of the same classes in Jämtland County. The soil moisture class with the highest percentage of reported occurence was the class "mesic-dry". These results are in agreeance with the literature describing nonnative habitats for garden lupine, however they do not reflect the facultative status it has received in native habitats. The spread of garden lupine can in other words be linked to the land cover and soil moisture that is found in the place of occurence. Future efforts that are needed are continous monitoring of garden lupine, harmonization of data through standardized inventory methods and validation of data. / Biologisk mångfald är förutsättningen för att avgörande ekosystemtjänster som rent vatten och ren luft ska fungera väl. Invasiva främmande arter (IAS) är ett allvarligt och långsiktigt problem som aktivt hotar den genetiska variationen inom ekosystem. I Sverige bedöms 20 procent av de 2000 främmande arterna vara invasiva eller potentiellt invasiva. En av de arter som klassas som IAS är blomsterlupin (Lupinus polyphyllus), vilken idag är vitt sprid över stora delar av Europa samt är bofast och reproducerande i Sverige. Syftet med studien var att ta reda på huruvida förekomst av blomsterlupin i Jämtland över 30 år har ett samband med viss typ av marktäcke och markfuktighet, samt om inrapporterade fynd har ökat med åren. Denna analys genomfördes genom att först statistiskt testa sambandet mellan inrapporteringar och rapporteringstillfälle. Därefter konstruerades en buffert med en radie på 5 meter runt inrapporterade artobservationer, för att sedan jämföra arean av respektive klass från Nationell Marktäckedata (NMD) och SLU Markfuktighetskarta inom bufferten mot den totala arean av respektive klass i hela Jämtland. Studiens resultat visade att blomsterlupinens förekomst kan associeras med vilken typ av marktäcke och markfuktighet som finns på platsen, samt att inrapporteringen av arten har ökat över åren. Arean av markatäckeklasserna inom bufferten för artobservation var inte proportionell mot den totala arean av respektive markatäckeklass i Jämtlands län. Lupin förekom vanligast inom marktäckeklasser exploaterad mark (50%; framförallt ”exploaterad mark väg/järnväg”), skog (30%) och övrig öppen mark (20%). Vad gäller markfuktighet så observerades endast blomsterlupin på två klasser, och arean för dessa klasser inom bufferten var inte proportionell mot arean för samma klasser i Jämtlands län. Markfuktighetsklassen som hade störst procentuell andel av inrapporterade fynd var klassen ”torr-frisk”. Dessa resultat överensstämmer med litteraturen som beskriver icke inhemska habitat, däremot reflekterar inte dessa resultat den fakultativa statusen som blomsterlupin har fått i dess inhemska habitat. Mina resultat visar att blomsterlupinens utbredning kan kopplas till den marktäcke och markfuktighet som finns på fyndplatsen. Framtida insatser som behövs är fortsatt övervakning av blomsterlupin, harmonisering av data genom standardiserade inventeringsmetoder och validering av data.
1610

Processen för bygglov : De sökande småhusägarnas perspektiv och fuktproblem i Stockholms Stad

Al-Wandi, Karar January 2023 (has links)
Purpose: The purpose of this study is to identify problems and shortcomings in the process of building permits from the perspective of small house owners in Stockholm. The purpose of this study is also to present future improvements. Methods: The method for this study contains both literature study and a case study. The case study consisted of a digital survey and interviews with small house owners and with the municipality´s building permit department. The digital survey consisted of questions about previous experiences of the building permit process to then investigate where there are shortcomings and weaknesses. Results: The results gave a wider perspective of how the small house owners experience the building permit process and how the municipality works through challenges and improves the process. The digital survey showed that several were dissatisfied with the processing time and experienced it as a long period. The respondents also experienced it as a difficulty when it comes to submitting correct documents requested by the municipality and that there are high building permit fees. A concrete improvement measure is that Stockholm municipality clarifies the building permit process steps regarding processing times and other weaknesses that arise on the website. Conclusions: The conclusion of this work is that Stockholm municipality updates the website, so that applicants with less knowledge and experience regarding building permits can get a better idea and possibly follow the schedule and budget they planned for the project. To avoid damage caused by damp during the project, it is possible to undergo a so-called moisture safety design. Stockholm municipality can introduce more employees within the building permit department to be prepared for periods where there is high pressure in building permit matters.

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