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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.
211

Analysis of the mechanical behavior of wood by means of digital image correlation

Brabec, Martin January 2016 (has links)
The full-field optical techniques such as e.g. a digital image correlation are capable to fully reflect the natural wood heterogeneity. Therefore, this thesis aspires to contribute to the experimental mechanics of wood and wood-based composites by the implementation of the full-field optical technique based on the digital image correlation to the standard mechanical tests. A supplementation of the conventional displacement sensors should help to obtain more precise mechanical characteristics and to do more sophisticated analyses of the deformation behaviour of wood and wood-based composites. The experimental part of the thesis is divided into the five independent case studies listed as the original papers. The measurements were carried out on the most wide-spread wood species in central Europe such as European beech (Fagus sylvatica, L.) and Norway spruce (Picea abies, L. Karst). Beside the solid wood, the new wood-based sandwich structure, which consists of a core made from birch plywood and the particleboard facings, was investigated too. The loading of the samples was carried out using of the standard mechanical tests such as tension, compression, three-point bending and torsion test. In the first study, the full-field deformation data were used to indentify reasons for the non-standard deformation behaviour of spruce and beech wood during compression parallel to grain. Reason for this was recognized in the abrubt compression of damage zones located near the compression plates, which induced the expansion of the middle zone located between them. The second study aimed to find out neutral axis position in native and thermally modified beech wood during the conventional three-point bending test. The relative neutral axis position was obtained from mutual position of the neutral axis and centroidal axis, which was determined based on the appropriate image processing methods. It was found that the neutral axis and centroidal sample axis are almost coincident. Objective of the third study was to determine both longitudinal shear moduli of beech wood with help of the full-field shear strains, obtained from a single torsion test, together with use of the appropriate analytical solutions for the calculation of the stress distribution within the radial and tangential direction on the longitudinal-radial and longitudinal-tangential sample surfaces. Both longitudinal shear moduli increasingly mutually differed as the load increases. Within the fourth study, verification of the elastic material model used in finite-element analyses was carried out with help of full-field deformations induced around notches within dog-bone shaped sample during the uniaxial tension. Great correlation was found between numerically predicted and experimentally measured strain data sets for both longitudinal-radial and longitudinal-tangential shear planes. The fifth study dealed with the characterization of elastic deformation behaviour of newly developed wood-based composite with a sandwich structure. Based on the full-field strain analysis the local strain concentrations were identified. They took place within the core during flatwise compression, and within the facings, when the edgewise compression test was done. A variety of presented results confirmed widespread applicability of optical methods in the mechanics of materials. Therefore, the utilization of full-field optical method based on digital image correlation in experimental mechanics of wood and wood-based composites can be highly recommended.
212

Sensitivity studies with a surface and channel runoff module coupled to a mesoscale atmospheric model

Mölders, Nicole, Rühaak, Wolfram 06 December 2016 (has links)
A module to investigate ground water recharge was developed, and implemented into the mesoscale meteorological model GESIMA (Geesthacht’s simulation model of the atmosphere) as well as coupled to a soil-vegetation scheme. Important features of the ground water module are the determination of surface and channel runoff. A comparison of the results provided by GESIMA with and without consideration of surface and channel runoff shows a remarkable impact of surface runoff on the soil moisture fluxes. Substituting water meadows by willow-forests demonstrates their importance for soil moisture fluxes. / Ein Modul zur Untersuchung von Grundwasserneubildung wurde entwickelt, in das mesoskalige meteorologische Modell GESIMA (Geesthachter Simulationsmodell der Atmosphäre) integriert und an ein Boden-Vegetationsmodell gekoppelt. Wesentliche Bestandteile des Grundwassermoduls sind die Berechnung des Oberflächen- und Gerinneabflusses. Ein Vergleich der Ergebnisse von GESIMA, die mit und ohne Oberflächen- und Gerinneabfluss erstellt wurden, belegt einen deutlichen Einfluss des Oberflächenabflusses auf die berechneten Feuchteflüsse im Boden. Untersuchungen zum Einfluss von Auenwäldern auf die Grundwasserneubildung belegen deren Bedeutung für die Wasserflüsse im Boden.
213

Využití recyklovaného dřeva ve výrobě dřevotřískových desek

Havelková, Hana January 2017 (has links)
The research was partially inspired by three-layer particle boards with a density of approximately 600 kg/m3 in various variants. The recycled wood was used for manufacture these particleboards in different portion: 10, 30, 60 and 90%. Of each variant were produced two boards of dimensions 600 x 600 x 12 mm, altogether eight boards. Laboratory produced chips of recycled material and chips of pure wood were separated in the surface and core layer. The chips were separated by sieve analysis. Subsequently they were prepared and processed into boards with different amounts of recycled wood. Also, two boards were pressed from a control chips from Kronospan Jihlava that used in the production mixed chips with recycled wood and which provided a reference desks of industrial production for this research too. The moisture content, density, swelling properties, bending strength, modulus of elasticity and tensile strength were determined on the ten boards produced in laboratories Mendel University in Útěchov and on four boards from Kronospan. Properties were compared with control and reference particleboards as well as between each tested group using Analysis of variance (ANOVA) and descriptive statistics.
214

Rozhraní pro jádro antivirového software / Interface for Core of Antivir Software

Valouch, Tomáš January 2008 (has links)
This master's thesis is dealing with problematics of antivirus program development. It describe evolution of viruses, antiviruses and it is trying to estimate the future development in this area of interest. There is described a design of graphic user interface for antivirus program. Finally are dicussed possible approaches for implementing the graphics user interface for forementioned antivirus program. Important part of this thesis is part which is dealing with description of implementation of mentioned user interface.
215

Sustainable bathroom design / Hållbar badrumsdesign

Johansson, Josefine, Zöllner Wohlfart, Lisa January 2017 (has links)
Skanska is one of the leading construction companies in Sweden when it comes to sustainable construction. Buildings are responsible for 40 % of both the global energy consumption and the global resources. With the current demand on housing, the building pace needs to increase whilst improving on sustainability. The level of industrialisation in the construction sector is still low compared to other sectors. Prefabricated components such as walls or slabs are common and during the last decade, prefabricated bathroom modules (henceforth referred as pods) have been introduced and are now used quite frequently in commercial buildings. A pod is a completely factory manufactured bathroom that is just lifted in place. The aim of this master thesis is to evaluate pods from a sustainable perspective and compare them to a traditional site built bathroom. Data is collected through field studies, interviews, a survey, reference projects and research.The analysis consists of seven key factors, Design, Human Resources, Waste, Time, Transport, Economy and Energy. The analysis resulted in improving four of the seven key factors when using pods; Human resources, waste, time and economy. The main benefit was reduced production time and thereby large cost savings, that for the reference project was 6,6 % of the total project cost. Usually, life cycle costs are not included in the initial costings, which gives a misleading price. Pods are a suitable concept for projects with at least 25-30 bathrooms, where the end user does not affect the design and where there is at least 20 bathrooms for each model. / Skanska är ett av de ledande byggföretagen inom hållbarhet i Sverige. Byggnader står för 40 % av både den globala energianvändningen och de globala resurserna. På grund av dagens rådande bostadsbrist behöver byggtakten öka och samtidigt bli hållbarare. Industrialiseringen inom byggsektorn är jämfört med andra branscher låg, men prefabricerade komponenter såsom väggar och bjälklag används i stor utsträckning. Under det senaste decenniet har även prefabricerade badrumsmoduler blivit allt vanligare i kommersiella projekt. En modul är ett komplett badrum, tillverkat i fabrik, som enbart lyfts på plats och kopplas in. Syftet med arbetet är att utvärdera modulkonceptet ur ett hållbarhetsperspektiv och att jämföra det med ett traditionellt platsbyggt badrum. Data har samlats in genom studiebesök, intervjuer, enkät, referensprojekt och bakgrundsstudier. Analysen baseras på sju nyckeltal, design, personalresurser, spill och förluster, tid, transport, ekonomi samt energi. Användning av moduler resulterar i en förbättring i fyra av sju nyckeltal, personalresurser, spill och förluster, tid och ekonomi. Största fördelen är den förkortade produktionstiden, vilket i sin tur leder till minskade kostnader. För referensprojektet blev kostnadsbesparingarna 6,6 % av den totala projektkostnaden. Vanligtvis är livscykelkostnader i dagsläget inte inräknade i de initiala kalkylerna, vilket ger en missvisande projektkostnad. Moduler är lämpade för projekt med minst 25-30 badrum, där slutanvändaren inte påverkar design och där det är minst 20 badrum per modell.
216

Att dekonstruera enfamiljshuset: Normbrytande hushåll i folkhemmets arv / Deconstructing the Single-Family House: Norm-Breaking Households in the Heritage of "Folkhemmet"

Enbom, Lisa January 2020 (has links)
Våra hem har anpassats och formats av samhälleliga förändringar, politiska reformer och utopiska ideologier. Normer, regleringar, statliga lån och bidrag har styrt familjer till att bestå av ett visst antal personer, samt att deras hem skall fungera och se ut på ett visst sätt. Enfamiljshuset blev en symbol för kärnfamiljen, bestående av två vuxna och deras två gemensamma barn. Trots att ungefär 30% av alla barnfamiljer i Sverige bor i alternativa familjekonstellationer ritas bostäder forfarande främst för kärnfamiljen. I det här projektet studeras Sveriges befintliga enfamiljshusbestånd, med mål att undersöka denna typologis möjligheter att bebos av fler versioner av hushåll. Genom att analysera fallstudiens modulkonstruktion avser detta projekt erbjuda ett förslag som kan återskapas som en generell lösning för andra modulbyggda enfamiljshus. I fallstudien ifrågasätts och dekonstrueras den rumsstruktur och de funktioner som ärvts från folkhemstiden, för att istället föreslå en bostad med fokus på ljus, visuell kontakt och mer generösa delade rum för hushållet. / Swedish homes have been adapted to and shaped by societal changes, political reforms, and utopian ideologies. Norms, regulations, governmental loans, and subsidies have induced families to consist of a specific number of people and influenced the functions and aesthetics of their homes. The single-family house became a symbol for the nuclear family, consisting of two adults and their common two children. Although almost 30% of the Swedish families with children live in alternative family constellations, homes are still mainly designed for the nuclear family. This project is studying the existing dwelling stock of single-family houses in Sweden, aiming to investigate this typology's possibilities to accommodate more versions of households. Examining the module construction of the case study, this project intends to find a proposal that can be remade as a general solution for other modular single-family houses. In the case study, the room structure and functions inherited from ”folkhemmet” are questioned and deconstructed, while proposing a dwelling with a focus on light, visual contact, and more generous shared spaces for the household.
217

Bitech. Ett front-end-projekt : En digital lösning för byggarbetsplatsen. / Bitech. A front-end project : A digital solution for the construction site.

Mineur, Olle, Gong, Hemming, Gustavsson, Emelie, Holmegren, Sabrina, Ibrahim, Ramon, Kharaghani, Shayan, Palmér, Mervan, Wilnerzon, Roberto January 2024 (has links)
Den här rapporten beskriver resultaten och metodologierna för Bitech front-end-projektet, ett omfattande mjukvaruutvecklingsinitiativ som syftar till att digitalisera och effektivisera verksamheten på byggarbetsplatser. Projektet använder avancerade webbteknologier för att skapa användarvänliga, dynamiska och responsiva gränssnitt som är lämpliga för både platsbaserade och administrativa behov inom byggbranschen. Viktiga aspekter av projektet inkluderar integration av hantering av realtidsdata, mobilkompatibilitet för att säkerställa åtkomst på olika enheter, och robusta säkerhetsåtgärder för att skydda känslig projektdata. Under hela utvecklingsprocessen antog teamet agila metoder, med betoning på iterativ utveckling, kontinuerlig testning och regelbunden kundfeedback, vilket underlättade en flexibel och responsiv utvecklingsmiljö. Denna rapport ger en detaljerad analys av projektets utfall, lärdomar och rekommendationer för framtida initiativ som syftar till att öka den teknologiska adoptionen inom byggindustrin.
218

Problematika zjišťování statického modulu pružnosti betonu v konstrukcích / The issue of determination of the static modulus of elasticity of concrete in structures

Halamová, Romana January 2017 (has links)
The thesis deals with the measurement of the elastic modulus of concrete in existing structures and possibilities of applicability of equations for the calculation of characteristic values of concrete compressive strength on the modulus of elasticity. The modulus of elasticity is determined by dynamic and static methods on specimens taken from the concrete blocks, whose composition varies by a water cement ratio and varying amounts of admixtures. In conclusion, the results of the measurements are compared and the characteristic values of the modulus of elasticity is determined.
219

Vliv provzdušnění a ošetřování na vývoj modulu pružnosti betonu / Influence of Air Entrainment and Curing on Development of Elastic Modulus of Concrete

Bartulíková, Radka January 2013 (has links)
Master's thesis deals with influence of various factors on the concrete compressive strength and modulus of elasticity. This work concentrates mainly on the influence of early curing and air entrainment of concrete. One part of this work is the evaluation of laboratory measurement, which was carried out on cubes of standard and norm prisms. The development of elastic moduli was monitored in time to 730 days of age with respect to air entrainment and curing conditions. The second part of the experiment deals with a comparison of theoretical creep curves depending on the value of the modulus of elasticity based on different standards. Again, the air entrainment effect and influence of initial conditions are reflected.
220

Utveckling och tillämpning av miljödokumentation som verktyg för produktutveckling : En fallstudie på förvaringsserien Space från Thule Möbler AB

Plahn, Maria, Olsson, Anna January 2016 (has links)
Thule Möbler AB in Kungsör, Sweden, is a retailer and manufacturer of furniture and fixtures for offices. They have previously worked with a general environmental declaration which describes the company’s overall environmental work, but they see a need for declaring the environmental performance of specific products. It is seen as an advantage if the environmental declaration can be used in product development to integrate consideration for environmental issues in the development process as well. The company also wish to develop and improve an existing series for office-storage, called Space. The work conducted in this paper is based on a product development process combined with a general research process which consists of a pre-study that describes the work of developing an environmental declaration and a case-study that includes the testing of the environmental declaration in the development of the office-storage Space. The methods used for developing the environmental declaration are literature reviews on standards for environmental declaration, scientific papers on the subject, environmental declarations from other companies and literature concerning productdevelopment tools and their structure. The use of the environmental declaration as product-information is tested and evaluated by trials on the intended user while the use of the environmental declaration as a product development tool is tested through the case-study. The case-study is based on a product development process that includes different product development tools, user-studies and analysis of the market. The user-studies and market-analysis are conducted as observation, questionnaires,interviews and a small literature review. The result is described both for the pre-study with the design of the environmental declaration and the case-study with the outcome of the product development. The environmental declaration consists of three documents, one template to be filled, one instruction for filling out the template, one spreadsheet containing the data to fill in and one example of a filled in declaration. The product consists of modules in the size 800x400x400mm that are connected by connection-brackets. The modules can be fitted with doors and handles, shelves and partitions, base and attachments for small-storage. The modules can be placed in six different ways in relation to each other and can be rearranged when needed. They can also be places free-standing or against a wall. The result of the case-study shows that the environmental declaration can be used as a tool for product development concerning evaluation and selection. The try-outs that are conducted indicates that the environmental declaration also is suitable for use as product-information. It is however important that the environmental declaration is continuously updated to ensure the data is correct, it should also be expanded to include other products. The developed product should be tested for strength and stability in accordance with Swedish standards. / Företaget Thule Möbler AB i Kungsör tillverkar och säljer möbler och inredning för kontor. De har sedan tidigare arbetat med en generell miljödeklaration som beskriver företagets övergripande miljöarbete men ser ett behov av att även redovisa miljörelaterade egenskaper för enskilda produkter. Det är en fördel om miljödeklarationen kan användas vid produktutveckling för att integrera miljöfrågor även under utvecklingsprocessen. Företaget vill dessutom utveckla en befintlig möbelserie, förvaringsserien Space. Arbetet baseras på en produktutvecklingsprocess kombinerad med en forskningsprocess bestående av en förstudie där miljödeklarationen tas fram efterföljt av en fallstudie där deklarationen testas under utvecklingen av förvaringsserien Space. Miljödeklarationen tas fram med hjälp av litteraturstudier innehållande standarder för miljödeklarationer, vetenskapliga artiklar i ämnet, befintliga miljödeklarationer från andra företag samt litteratur kring produktutvecklingsverktyg och dess uppbyggnad. Användandet av miljödeklarationen som produktinformation testas och utvärderas genom utprovning av användare medan deklarationen som produktutvecklingsverktyg testas i fallstudien. Fallstudien baseras på en produktutvecklingsprocess där olika produktutvecklingsverktyg, användarstudier och marknadsanalyser används. Användarstudier och marknadsanalys genomförs med hjälp av observationer, enkäter, intervjuer samt en mindre litteraturstudie. Resultatet redovisas både för förstudien där miljödeklarationens utformning beskrivs samt för fallstudien där resultatet av produktutvecklingen beskrivs. Miljödeklarationen består av fyra dokument, en mall för ifyllande av deklaration, en instruktion för ifyllande av deklaration, underlag för ifyllande av deklaration samt ett exempel på en ifylld deklaration. Den utvecklade produkten består av moduler i storleken 800x400x400mm som kopplas samman med hjälp av kopplingsbeslag. Till modulerna finns dörrar och handtag, hyllor och avdelare, sockel samt tillbehör för småförvaring. Modulerna kan placeras i sex olika lägen i förhållande till varandra samt möbleras om vid behov. De kan även placeras både fristående samt mot vägg. Resultatet av fallstudien visar att miljödeklarationen med fördel kan användas som produktutvecklingsverktyg för utvärdering och urval. De utprovningar som genomförs tyder även på att miljödeklarationen är lämplig att använda som produktinformation. Miljödeklarationen bör dock uppdateras kontinuerligt för att säkerställa informationens riktighet, den bör även utökas för att kunna tillämpas på fler produkter. Den framtagna möbeln bör testas gällande hållfasthet och stabilitet enligt Svensk standard.

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