Ventilation might seem like a minor consideration, but when properly installed, it can extend the life of the attic and roof structure of residential buildings saving huge dollar amounts in repair costs. The objectives of this study were to measure the wind effect on different kind of vents as the problem is vents are subjected to high wind loads during hurricane events and often fail causing water penetration and damage of interior contents. Wind-induced failure of rooftop vents during a hurricane may result in large openings in the roof that will allow water to penetrate into the building, a puncturing of the roof membrane, again allowing water infiltration, and detached rooftop vents can pose considerable threats as windborne debris. The study found that water infiltration through a vent system is dependent upon the differential pressure as well as the vent mechanism. For vents experiencing higher differential pressures, vent covers can be used during storms to reduce water infiltration. Active controls can also be designed to close the vents automatically as differential pressure increases based on the wind speed and wind angle of attack.

This is a final year project considering constructional techniques for joining cavity walls. The project is related to an ongoing scientific programme about the restoration of The City wall of Visby located on Gotland. The programme was set by Riksantikvarieämbetet as a reaction to a collapse of the outer masonry wall shell which took place in February 2012. The City wall of Visby is a medieval fortification built out of limestone during the 13th century. The wall is constructed as a cavity wall with two separate masonry shells connected to each other through an intermediate core. During the 14th century the wall was heightened which lead to a higher stress, especially in the outer wall face. This occurrence in combination with repeated frost bursts is most likely two of the reasons to why a part of the wall collapsed in 2012. The investigated techniques in this report are reconstructional masonry work using “through-stones”, wall ties out of steel and supportive buttresses. These techniques are investigated regarding their constructive actions and suitability for The City wall of Visby. Masonry work using “through-stones” consists of placing occasional masonry stones perpendicular to the remaining stones. In this way the two wall faces can be joined together. As well as “through-stones”, wall ties also provide a binding between the two wall faces. These ties can be made out of steel bars which ends are connected to each wall face. In this report wall ties are calculated considering tension in interaction with bending moment. A desirable quality for wall ties in this case is that they have the ability to follow the natural movements of the masonry wall without losing their binding capacity. Finally masonry buttresses are investigated, these are masonry units placed against the wall to support horizontal loadings. Buttresses vary in appearance; in this case they consist of limestone blocks laid against the wall face in a certain angle. Considering the state of equilibrium, adequate dimensions of the buttresses are defined. Calculations in this report are based on a number of assumptions regarding loading conditions of the wall combined with the specific constructional technique. Existing theories based on Eurocode’s are not always possible to apply on medieval constructions such as The City wall of Visby. The results in this report show that all mentioned techniques could be applied on The City wall of Visby if they are constructed with the right dimensions in combination with other preventive measures against problems due to water and frost. However, considering the fact that The City wall of Visby is a cultural heritage the suitability differs between the constructional techniques. / Detta examensarbete behandlar byggnadstekniska metoder med syftet att sammanbinda skalmurar. Arbetet utförs i samband med ett pågående forsknings- och utvecklingsprojekt rörande restaureringen av Visby ringmur på Gotland. Forskningsprojektet startades på uppdrag av Riksantikvarieämbetet efter ett murras i februari 2012. Visby ringmur är en medeltida befästning av gotländsk kalksten som till huvudsaklig del uppfördes under åren 1250-1288. Muren är konstruerad som en skalmur vilket innebär en icke homogen mur bestående av två murskal med mellanliggande kärna. Senare på 1300-talet förhöjdes muren vilket bidrog till en överbelastning av främst det yttre murskalet. Detta i kombination med upprepad frostsprängning är sannolikt två av orsakerna till murraset 2012. Metoderna som undersökts är ommurning med bindstenar, sammanbindning med kramlor och dragjärn samt uppstöttning med kontreforter. Dessa metoder studeras i fråga om verkningssätt samt lämplighet för Visby ringmur. Murning med bindstenar innebär att stenar med regelbundet mellanrum i ett murskift placeras tvärgående med kortsidan utåt, detta för att skapa en sammanbindning mellan murskalen i en skalmur. Kramlor och dragjärn ska även de verkar som förbindare mellan murskalen, de kan exempelvis utgöras av ett rundstål som infästs i vardera murskal. I rapporten undersöks dessa utifrån dragkraft i kombination med dess böjmoment. Önskvärt är att såväl kramlor som dragjärn ska kunna följa murens naturliga rörelser samtidigt som de ska sammanbinda murskalen. Slutligen undersöks kontreforter vilka muras mot skalmuren med syftet att ge stöd och uppta horisontala krafter. Kontreforter kan variera i utseende, i detta fall studeras kontreforter som muras av kalksten i vinkel mot murväggen. Med hjälp av ett jämviktsförhållande undersöks lämpliga dimensioner för kontreforterna. Alla beräkningar i denna rapport baseras på ett antal antaganden om lastförhållanden för muren i samverkan med vald byggnadsteknisk metod. Teorier enligt Eurokoderna inte är utformade för äldre murverkskonstruktioner och därav inte alltid tillämpbara. Resultaten visar att alla nämnda metoder skulle kunna tillämpas på muren om de utförs med lämpliga dimensioner i kombination med andra förebyggande åtgärder mot fukt- och frostproblemen. Dock skiljer sig lämpligheten för de olika metoderna åt med tanke på bevarandet av ringmurens kulturhistoriska värde.

Detta examensarbete har utförts vid högskoleingenjörsprogrammet Byggteknik och design vid Kungliga Tekniska högskolan och i samarbete med Ramböll Sverige. Syftet med denna rapport är att undersöka och analysera dagens ytterväggskonstruktioner för framtidens energieffektiva flerbostadshus.  Ytterväggskonstruktionen som är en del i byggnadens klimatskal, har en viktig och betydelsefull funktion för att kunna klara av framtida byggnaders energikrav. För att en väggkonstruktion ska fungera finns det en rad andra påverkande faktorer som måste tas hänsyn till. Därför kommer examensarbetet att fokusera på ytterväggskonstruktioners byggfysikaliska egenskaper såsom lufttäthet, fukt, uppbyggnad och beständighet. För att kunna lösa uppgiften har vi varit i kontakt med åtta olika byggnadsentreprenörer i Stockholmsområdet och utfört studiebesök ute i produktionen. Det finns flera faktorer som styr valet av ytterväggskonstruktion för projektet och på grund av detta finns det en rad olika typer av ytterväggskonstruktioner som används i dagens byggande av flerbostadshus. I vår jämförelse mellan sex olika ytterväggskonstruktioner har vi analyserat byggfysikaliska egenskaper och produktionsmetoder utifrån samma grundparametrar. Eftersom ytterväggarna skiljer sig mellan lätt respektive tung stomme har vi valt att presentera en från varje kategori. Enligt vår bedömning i vår analys har vi kommit fram till att en lätt utfackningsvägg med stålregelstomme och en tung väggkonstruktion med platsgjuten skalväggsstomme har de bästa förutsättningarna för att i framtiden utgöra de främsta alternativen inom ytterväggskonstruktioner för flerbostadshus.Rapporten är skriven för läsare som antas ha viss kunskap inom området byggteknik, dvs. den riktar sig främst till intressenter till byggbranschen och studenter inom området. / This thesis has been carried out at the Bachelor's program of construction engineering and design at the Royal Institute of Technology and in collaboration with Ramböll Sweden. The purpose of this report is to examine and analyze today's outer wall structures for the future of energy efficient buildings. The outer wall construction that is part of the building envelope has an important and significant flaw to meet future energy requirements of buildings. For a long time different wall construction projects have been designed to create wall panels with low U-values. For a wall structure to function, there are a number of confounding factors to be taken into account. Therefore, the thesis will focus on outer wall structure building physical properties such as air density, moisture, structure and stability.  In order to solve the task we have been in contact with eight different contractors in the Stockholm area and conducted field trips out in production. There are several factors that determine the choice of exterior wall construction for the project and because of this there are a number of different types of exterior wall structures used in today's construction of apartment buildings. In our comparison of six different wall constructions, we have analyzed the construction of physical characteristics and production methods on the same basic parameters. Since the outer walls differ between light and heavy body, we have chosen to present one from each class. Our conclusion is that a light stud walls with steel stud frame and a heavy wall construction with in-situ shell wall structure is best equipped to continue being the main option in exterior wall construction for apartment buildings. The report is written for readers who knowledgeable in the field of building technology, i.e. it is mainly addressed to interested parties in the construction industry and students in the field.

No description available.

Västlänken i Göteborg är ett tunnelprojekt för järnväg som skall byggas under centrala Göteborg. Tunneln byggs genom både berg och lera, projektet kommer att använda sig av ett flertal tekniker och konstruktionslösningar. Västlänken är ett av de första stora infrastrukturprojekt i Sverige där slitsmurar används som permanenta konstruktioner. På uppdrag av Trafikverket har två olika typer av stödmurskonstruktioner undersökts med avseende på deras klimatpåverkan. Konstruktionslösningarna är en temporär spont med tillhörande tunnelvägg och en slitsmur. Slitsmuren används både som en temporär konstruktion under byggskedet och en del i den permanenta tunnelväggen. Slitsmurar har först nyligen blivit godkända att användas som delar av permanenta konstruktioner av Trafikverket. Av denna anledning finns det inte mycket information om konstruktionens klimatpåverkan. Syftet med rapporten är att undersöka klimatpåverkan från de två olika konstruktionslösningarna. Jämförelsen har gjorts med hjälp av livscykelanalyser för att få den mest övergripande analysen. En livscykelanalys (LCA) är ett verktyg för att synliggöra en produkts totala miljöpåverkan under dess livstid. Detta åstadkoms genom att alla de olika delprocesser som krävs för att skapa produkten inventeras och analyseras. LCA har utförts med datorprogrammet SimaPro och databasen Ecoinvent. I SimaPro har båda konstruktionslösningarna modellerats och deras miljöpåverkan sedan beräknats med ReCiPe 2016. Indata till LCA har samlats in från ritningar och diskussioner med experter på området. Resultatet från livscykelanalysen visar att slitsmurarna i detta projekt har större klimatpåverkan än konstruktionslösningen med spont och en platsgjuten betongmur. För slitsmuren står armering samt betong för den största delen av klimatpåverkan och för sponten är det den stora mängden stål som krävs vid de kraftiga dimensionerna. Då en del av konstruktionerna inom projektet ej var färdigprojekterad när denna rapport författades rekommenderas ytterligare studier på ämnet för att validera resultaten / The West Link Project is as tunnel project for the railroad that will be constructed below central Gothenburg. The project is built through clay and solid rock thus making use of several techniques and structural solutions. The West Link Project (Västlänken) is the first major infrastructure project in Sweden where diaphragm walls are used as a part of the permanent structure. Two different structures have been examined on behalf of the Swedish Transport Administration, with regards to their climatic impact. The two structures examined are a temporary sheet pile with a cast-in-place concrete wall that is used as a part of the tunnel wall, and a diaphragm wall. The diaphragm wall is used as an earth retaining wall during the construction stage and as a part of the permanent tunnel wall. Diaphragm walls have just recently been approved as parts of permanent structures by the Swedish Transport Administration. Due to this there isn’t a lot of information available on their climatic impact. The purpose of this paper is to examine the climatic impact of these two different structures. The comparison has been performed by the use of a lifecycle analysis to get the most comprehensive analysis. A lifecycle analysis (LCA) is a tool that helps to get a perspective on a product’s total environmental impact over the course of its lifetime. This is accomplished by doing an inventory of all the different processes involved in its production. For the LCA the computer program SimaPro, and the database Ecoinvent were used. In SimaPro both of the structure have been modelled and their environmental impact has been calculated with ReCiPe 2016.Input for the LCA have been gathered from drawings and communication with experts. The result of the LCA shows that in this project the diaphragm walls have a higher climatic impact than the sheet pile and concrete wall. With regards to the diaphragm wall the majority of its climatic impact is from the large amounts of reinforcement and concrete used. For the sheet pile the steel used to manufacture sheets of the dimensions used in the project is the largest contributing factor. Due to the fact that some of the structures in the project are still being at the design stage at the time of writing further studies are recommended to validate the results.

The present thesis presents new renewable, antimicrobial and biodegradable superabsorbent polymers (SAPs), produced from the cell wall of zygomycetes fungi. The cell wall was characterized and chitosan, being one of the most important ingredients, was extracted, purified, and converted to SAP for use in disposable personal care products designed for absorption of different body fluids. The cell wall of zygomycetes fungi was characterized by subsequent hydrolysis with sulfuric and nitrous acids and analyses of the products. The main ingredients of the cell wall were found to be polyphosphates (4-20%) and copolymers of glucosamine and N-acetyl glucosamine, i.e. chitin and chitosan (45-85%). The proportion of each of these components was significantly affected by the fungal strain and also the cultivation conditions. Moreover, dual functions of dilute sulfuric acid in relation to chitosan, i.e. dissolution at high temperatures and precipitation at lowered temperatures, were discovered and thus used as a basis for development of a new method for extraction and purification of the fungal chitosan. Treatment of the cell wall with dilute sulfuric acid at room temperature resulted in considerable dissolution of the cell wall polyphosphates, while chitosan and chitin remained intact in the cell wall residue. Further treatment of this cell wall residue, with fresh acid at 120°C, resulted in dissolution of chitosan and its separation from the remaining chitin/chitosan of the cell wall skeleton which was not soluble in hot acid. Finally, the purified fungal chitosan (0.34 g/g cell wall) was recovered by precipitation at lowered temperatures and pH 8-10. The purity and the yield of fungal chitosan in the new method were significantly higher than that were obtained in the traditional acetic acid extraction method. As a reference to pure chitosan, SAP from shellfish chitosan, was produced by conversion of this biopolymer into water soluble carboxymethyl chitosan (CMCS), gelation of CMCS with glutaraldehyde in aqueous solutions (1-2%), and drying the resultant gel. Effects of carboxymethylation, gelation and drying conditions on the water binding capacity (WBC) of the final products, were investigated. Finally, choosing the best condition, a biological superabsorbent was produced from zygomycetes chitosan. The CMCS-based SAPs were able to absorb up to 200 g water/g SAP. The WBC of the best SAP in urine and saline solutions was 40 and 32 g/g respectively, which is comparable to the WBC of commercially acceptable SAPs under identical conditions (34-57 and 30-37 g/g respectively). / <p>Disputationen sker fredagen den 1 oktober kl. 10.00 i KA-salen, Kemigården 4, Chalmers, Göteborg</p>

Plant cells are routinely exposed to various pathogens and environmental stresses that cause cell wall perturbations. Little is known of the mechanisms that plant cells use to sense these disturbances and transduce corresponding signals to regulate cellular responses to maintain cell wall integrity. Previous studies in rice have shown that removal of the cell wall leads to substantial chromatin reorganization and histone modification changes concomitant with cell wall re-synthesis. But the genes and proteins that regulate these cellular responses are still largely unknown. Here we present an examination of the nuclear proteome differential expression in response to removal of the cell wall in rice suspension cells using multiple nuclear proteome extraction methods. A total of 382 nuclear proteins were identified with two or more peptides, including 26 transcription factors. Upon removal of the cell wall, 142 nuclear proteins were up regulated and 112 were down regulated. The differentially expressed proteins included transcription factors, histones, histone domain containing proteins, and histone modification enzymes. Gene ontology analysis of the differentially expressed proteins indicates that chromatin & nucleosome assembly, protein-DNA complex assembly, and DNA packaging are tightly associated with cell wall removal. Our results indicate that removal of the cell wall imposes a tremendous challenge to the cells. Consequently, plant cells respond to the removal of the cell wall in the nucleus at every level of the regulatory hierarchy.

Difficulties in controlling and forecasting avocado fruit ripening and the highly perishable nature of the crop once harvested, are the major causes of concern for avocado traders. In particular, the simultaneous presence of many suppliers may account for increased fruit variability during ripening. Avocado is a climacteric fruit with consistent ethylene production after harvest which is also related to high perishability. However, the mechanisms regulating ethylene biosynthesis and mesocarp softening are not completely understood. In order to study such effects, avocado fruit from different growing areas and harvested at various maturity stages, were investigated and the biochemical and physiological changes during ripening at both 18 and 23°C were studied. Mesocarp softening and fatty acid content discriminated fruit maturity and growing area, respectively, whereas C7 sugars (D-mannoheptulose and perseitol) discriminated length of fruit shelf life. For the first time, oleic acid content presents in the oil mesocarp was found to depend on fruit sources making of this a suitable indicator of avocado fruit growing area. In contrast, sugar content declined along fruit maturity and ripening. In particular the mannoheptulose presents in avocado mesocarp might be use to estimate avocado fruit shelf life. Indeed, fruit harvested late in season were found to have a lower C7 content than earlier harvest fruit and a faster softening, regardless fruit source. However, sugars content changed between growing area, thus a general C7 threshold defining fruit storability seems to be not definable. Furthermore, other possible indicators of fruit maturity and/or ripening stage have been searched in the cell wall constituents of avocado mesocarp. Thus, the structural carbohydrates profile of avocado mesocarp investigated with a new immunological method changed during ripening and harvest time (early and late season), suggesting a possible effect of cell wall composition on fruit ripening regulation. Also, the possible use of ethylene application in reducing the high heterogeneity noted on imported fruit from South Africa was also evaluated through different consignments. Results showed ethylene efficacy changed depending on harvest time and fruit dimension with less efficacy of the treatment on fruit harvested at the end of the season and characterised by smaller size.One of the most commercialized avocado cultivars, Hass, is peculiar in that its skin colour changes from green to deep purple as ripening progresses. The most common ripening indicator of avocado fruit is the mesocarp firmness and the destructive nature of this evaluation increases losses in the avocado industry. The availability of a non-destructive indicator of fruit ripening represents an important advantage for avocado consumers and importers. Thus, the possible relationship between mesocarp softening, skin colour were objectively evaluated (C*, L*, and H°), and the main pigment, cyanidin 3-O-glucoside, was investigated. Cyanidin 3-Oglucoside was confirmed to be the main anthocyanin present in avocado cv. Hass peel, regardless of preharvest factors. However, differences in its content were noted between shelf life temperatures. A higher relationship between hue angle and firmness was detected in late harvest fruit, whereas no correlation was found between anthocyanin content and firmness. Avocado skin is also involved in defence mechanisms due to the presence of antifungal and phenolic compounds. These phenolic compounds represent a natural protection against pathogenic infections and seem to be down regulated during ripening. The main phenolics were identified and quantified, using a new analytical method which was validated and optimised. Epicatechin, chlorogenic acid and procyanidin B2 were found to be present in the skin tissue and quantified using this assay and found to vary during shelf life and seasons. Although phenolics were present in minor amounts, in avocado pulp they are involved in mesocarp discoloration incidence, and therefore with fruit postharvest quality. Due to a lack of information, a new straightforward method for the identification and quantification of the main phenolics present in avocado mesocarp was developed. Finally, a commercial trial was undertaken to ensure that the results obtained in the laboratory can be reproduced in the market place. In conclusion, postharvest markers can define avocado fruit maturity and growing area and give guidelines in the control of avocado shelf life. Moreover, new methods for the investigation of the phenolic profiles (peel and mesocarp) and the characterisation of cell wall structures can be further tools in the management of avocado fruit postharvest quality.

A study of the fluctuating wall pressure and unsteady velocity field in a flat plate turbulent boundary layer flow was conducted over a moderate range of Reynolds numbers to better understand the mechanisms by which the two fields are coupled. Individual and coincident measurements of the fluctuating pressure and velocity fields were acquired using a 20 element hydrophone array and a two-component Laser Doppler Anemometer, respectively. Estimates of the velocity power spectral density (PSD) revealed two primary trends predicted by turbulence theory, k⁻¹ in the region of (ky) = 10⁰ due to anisotropy of the large scales, and k⁻⁵/³ for larger values of (ky) where structures appear more isotropic. The mean velocity profiles, having been collapsed using outer scaling variables, exhibited the presence of a slightly adverse pressure gradient with a n = 6 power law shape. As for the fluctuating wall pressure, increased Reynolds numbers produced increases in the amplitude and frequency of the characteristic signatures from which the pressure spectral densities were also found to collapse reasonably well using outer scaling variables. The results suggest the location in the flow where the mechanisms responsible for driving the fluctuating wall pressure signatures reside. Space-time correlations and frequency-wavenumber analysis reveal a convective ridge in the fluctuating wall pressure corresponding to the passage of several organized structures at 75% of the free stream velocity for all Reynolds numbers tested. / text

<p>The fiber suspensions in the production line from wood topaper are subjected to many types of chemical and mechanicalprocesses, in which the flow of the suspension is of vitalimportance. The flow of the suspension determines the degree ofuniformity of the fibers through the processing, which inreturn affects the properties of the fiber suspension. In orderto optimise the process, thorough knowledge of the suspensionflow is necessary, both on the level of suspension, fibernetworks and individual fibers. Knowledge of the fibersuspension behaviour combined with commercial CFD simulationprovides an efficient design method for any unit operation inthe papermaking process.</p><p>This work concentrates on macroscopic modeling of thebehaviour of fiber suspensions from 0.5-5% dry content, purefiber suspensions without fillers or additives. Any mechanismscausing the characteristic behaviour of the pulp suspensionhave not been included, they are only included through theirinfluence on the suspension parameters. Excluded mechanismsare, for instance, the fiber-fiber coupling mechanisms that arethe reason for the formation of fiber networks and parts offiber network, flocs.</p><p>By combining a rheology model for the bulk suspension, awall function that accounts for the slip layer and finallyintroducing turbulence, a model has been created that is ableto simulate the flow of most fiber suspensions. The flow of thesuspension is not constrained to any particular flowconditions; the models discussed in this work aim at describingthe behaviour of the suspension for all flow rates and flowtypes. The models are developed under simple flow conditions,where all variables can be controlled, but the models areintended for usage within the industry-based flows in real pulpand papermaking applications.</p><p><b>Keywords:</b>rheology, fiber, suspension, CFD, model, wall,slip, turbulence</p>