Dissertations / Theses: 'Densification of the building'

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Lans, Stina, and Albin Jakobsson. "BYGGNADSTEKNISKA LÖSNINGAR VID PÅBYGGNAD AV BOSTÄDER PÅ PARKERINGSHUS." Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Byggnadsteknik och belysningsvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-45678.

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Syfte: I Sverige råder det en stor bostadsbrist. En lösning för att skapa nya bostäder i tätbebyggda områden är vertikal förtätning. Detta kan ske via våningspåbyggnad av bostäder på parkeringshus. Denna typ av påbyggnad ställer dock krav på den befintliga byggnaden. Rapportens syfte är att fungera som ett underlag vid projektering av konstruktion, brand och installationer vid framtida projekt av liknande slag. Målet är vidare att analysera och sammanställa olika byggnadstekniska lösningar som används vid våningspåbyggnad av bostäder på parkeringshus. Detta skall besvaras genom följande frågeställningar: Vilka konstruktionstyper tillämpas vid våningspåbyggnad på ett parkeringshus och vilka krav ställer påbyggnaden på den befintliga stommen? Vilka brandkrav ställs på denna typ av våningspåbyggnad och hur uppfylls dessa? Hur förses påbyggnaden med installationer? Metod: Rapporten bygger på en kvalitativ fallstudie där intervjuer och dokumentanalyser legat till grund för empirin. För att styrka studien med teori har en litteraturstudie genomförts. Resultat: Resultatet visar att en lätt stomme har använts till samtliga våningspåbyggnader, däremot har valet av stommaterial skiljt sig åt. Kapaciteten på den befintliga byggnadens grund har varit avgörande för om en våningspåbyggnad varit möjlig. Placering av våningspåbyggnaden har berott på om boyta eller antalet parkeringsplatser prioriterats högst. Brandkraven på denna typ av byggnad kan likställas med kraven som ställs på en nybyggnad av bostäder. Detta har inneburit att förändringar på de befintliga parkeringshusen varit nödvändiga för att uppfylla kraven. Nya installationsschakt har placerats både in- och utvändigt av den befintliga byggnaden. Konsekvenser: De slutsatser och rekommendationer, utifrån rapportens innehåll, består främst av vikten i att göra en noggrann inventering av den befintliga byggnaden. Det handlar om byggnadens kapacitet och vilka eventuella förstärkningsarbeten som krävs innan en våningspåbyggnad. Begränsningar: Studien avgränsar sig från byggnadstekniska beräkningar och ekonomiska kalkyler. Arbetet har begränsats utifrån en viss mängd ord och tidsram, utan dessa hade möjligheten funnits att göra en mer djupgående analys av studiens referensobjekt. Detta genom att intervjua ytterligare aktörer inom fler konsultområden för de valda referensobjekten.
Purpose: In Sweden, there is a shortage of housing and a solution for creating new housing in urban areas is vertical densification. Vertical densification can be done by adding floors of housing on top of existing parking garages. This type of extension sets demands on the existing building. The purpose of this thesis is to serve as a basis for the planning of construction, fire requirements and installations for future similar projects. The goal is furthermore to analyze and compile various building-technical solutions that are used when floors of housing are built on top of existing parking garages. The goal is answered by the following questions: Which types of construction are used for additional floors of housing on top of parking garages and what requirements does the extension have on the existing building? What fire requirements are imposed on this type of extension and how are they fulfilled? How are the additional floors of housing provided with installations? Method: The report is based on a qualitative case study in which interviews and document analysis formed the basis of empirical data. To confirm the study with theory, a literature study has been conducted. Findings: The result shows that a light framework has been used for additional floors of housing, however, the choice of framework material has been different. The capacity of the existing building's foundation has been vital for whether an extension with housing has been possible. Placement of the extension has been due to whether the living space or the number of parking spaces is given as the highest priority. The fire requirements for this type of building can be equated with the requirements imposed on a new building of housing. This has meant that changes to the existing parking garages have been necessary to meet the requirements. New shafts for installations have been placed on both inside and outside of the existing building. Implications: The conclusions and recommendations, based on the content of the thesis, consist primarily of the importance of making an accurate inventory. It’s about the existing building's capacity and what possible reinforcement work it requires before an extension with housing. Limitations: The study delimits itself from construction engineering calculations and economic calculations. The work has been limited based on a variety of words and timeframe, without these it would be possible to make a more in-depth analysis of the study's reference objects. This would be done through interviewing more actors from additional consulting areas for the selected reference objects.

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Ribault, Clément. "Méthode d'optimisation multicritère pour l'aide à la conception des projets de densification urbaine." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI084/document.

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La population mondiale fait face, globalement, à une urbanisation expansive. Cet étalement urbain, souvent mal contrôlé, menace aussi bien l’environnement que la santé, la qualité de vie et la sécurité alimentaire des humains. Il est possible de le limiter en lui préférant la densification urbaine. Néanmoins, la complexité des phénomènes en jeu dans un tel contexte nous incite à penser que les responsables d’opérations de densification urbaine ont besoin d’outils pour les aider à faire les choix les plus pertinents possibles. Dans un premier temps, l’état de l’art présenté dans cette thèse montre que l’outil idéal n’existe pas, et que l’optimisation multicritère par algorithme génétique est une technique adaptée à l’aide à la conception de bâtiments. Les caractéristiques souhaitables pour une méthode d’assistance des concepteurs de projets de densification urbaine sont alors précisées. Nous recommandons de baser cette méthode sur le couplage entre un algorithme génétique et un outil capable de réaliser des simulations thermiques dynamiques (STD) de quartiers. Les capacités des logiciels de STD Pleiades+COMFIE (P+C) et EnergyPlus (E+) sont situées par rapport à ces exigences, puis un premier test d’optimisation d’un projet de densification urbaine en associant EnergyPlus à un algorithme génétique est présenté. Certaines lacunes de cette méthode peuvent être comblées par la plateforme en cours de développement dans le projet ANR MERUBBI. Dans un second temps, nous analysons donc les résultats d’une étude comparative entre P+C, E+ et l’outil MERUBBI, menée sur un projet de densification d’un îlot à forte densité urbaine. Ils montrent que ce dernier est fiable et particulièrement pertinent pour l’évaluation précise des interactions entre bâtiments. Dans un troisième temps, nous abordons la problématique de la diminution des temps de calcul, enjeu crucial pour que notre méthode d’aide à la conception soit réellement accessible aux professionnels du bâtiment. Nous proposons une technique de réduction de la période de simulation que nous présentons en détail. Enfin, la méthode d’optimisation développée est appliquée à la résolution de différents problèmes de conception du projet sus-cité, en utilisant E+. Nous montrons en quoi l’utilisation de l’outil MERUBBI enrichira cette approche, avant de conclure sur des perspectives de développement de notre méthode pour améliorer son interactivité
The world’s population is facing an expansive urbanization. This urban sprawl, which is often not well managed, is endangering the environment as well as human health, quality of life and food security. It can be controlled by favouring urban densification. Nonetheless, the complexity of the phenomena involved in such a context leads us to think that supervisors of urban densification operations need some tools to help them make the most relevant choices. This thesis begins with a literature review that shows the ideal tool does not exist, and explains why multi-objective optimization using a genetic algorithm is a suitable technique for building design aid. Then we clarify the desirable features of an assistance method for urban densification projects designers. We recommend to base this method on the coupling of a genetic algorithm with a district-scale dynamic thermal simulation (DTS) tool. We compare capabilities of EnergyPlus (E+) and Pleiades+COMFIE (P+C) DTS software with these requirements, then we present a first urban densification project optimization test associating EnergyPlus with a genetic algorithm. The platform under development in the ANR MERUBBI project can offset certain shortcomings of this method. Hence, in a second phase we analyze the results of a comparative study of P+C, E+ and the MERUBBI tool, carried out using a high-density district densification project as a test case. It shows that the latter is reliable and particularly relevant to precisely assess interactions between buildings. In a third phase we address the problematic of reducing the computing time, a major issue to make our design aid method truly accessible to building professionals. We propose a way of reducing the operating period length and present it in detail. Finally, our optimization method is used to solve various design problems of the above-mentioned project, using E+. We show how the use of the MERUBBI platform will enrich this approach before concluding with development ideas to make our method more user-friendly and interactive

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Soldemyr, Niklas, and Andreas Dahlberg. "ETT GESTALTNINGSFÖRSLAG FÖR NYA BOSTÄDER GENOM VERTIKAL FÖRTÄTNING : Utifrån lämplighetsanalys för vertikal förtätning, gestaltningspriciper samt plats- och mikroklimatsanalyser." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-64404.

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Den befolkningstillväxt som sker idag skapar utmaningar för det befintliga bostadsbeståndet och vår bostadsförsörjning. För att klara tillväxten bygger vi våra städer tätare och högre vilket skapar både möjligheter och utmaningar. Ett sätt att effektivisera redan exploaterad mark kan vara att genom vertikal förtätning skapa fler bostäder på befintlig bebyggelse. Syftet med detta examensarbete är att belysa hur våningspåbyggnad i en urban miljö kan gestaltas och vilken påverkan den kan ha på mikroklimatet. För att undersöka huruvida det är lämpligt att förtäta ett utvalt objekt genomfördes en lämplighetsanalys baserat på ett tidigare examensarbete av Larsheim (2007), vilken behandlar inventering av fastighetsbestånd för vertikal förtätning. Denna metod har bearbetats i samråd med planarkitekt på Luleå kommun innan den tillämpades på det utvalda förtätningsobjektet vilket renderade i att byggnaden kunde anses lämplig att förtäta på. För att beskriva byggnaden och dess närområdes arkitektoniska karaktär utfördes en analys enligt Thiis-Evensen (1994) metod. Med hjälp av Pena och Parshalls (2001) metod ”Problem seeking” syntetiserades den arkitektoniska karaktärsanalysen tillsammans med förtätningsteori och teori om mikroklimat. Syntesen gav ett förslag till gestaltningsprogram för hur våningspåbyggnaden skulle kunna gestaltas. Examensarbetet resulterade i ett gestaltningsförslag se del 6. Gestaltningsförslaget. Påbyggnaden består av 45 lägenheter som är placerad ovanpå ett befintligt parkeringshus i Luleå, bostäderna är fördelade på tre plan vilka vilar på en förlängd pelarstomme. Påbyggnaden öppnar upp för nya möjligheter till ett attraktivt boende i innerstaden och har dessutom kvalitativa grönytor för lek och socialt umgänge samt odlingsbara ytor i ett växthus. I syfte att positivt kunna påverka de förändringar som kan ske då stadens tak bebyggs har mikroklimatsanalyser utförts utifrån faktorerna sol, vind, luftkvalitet, ljud, snö samt fenomenet ”Urban heat islands”. Analyserna som utförts har påverkat val av form och material för det i del 6. presenterade gestaltningsförslaget. Det presenterade gestaltningsförslaget bör i ytterligare steg undersökas av annan part då detta inte kunnat utföras under examensarbetets gång. Den lämplighetsanalys som testats i detta examensarbete bör valideras och utformas i närmre samarbete med intressenter och kommun för att säkerställa att rätt kriterier och tillvägagångssätt används då lämplighet för påbyggnad ska bestämmas.
The current ongoing population growth creates challenges for the existing housing stock and our housing supply. To handle this population growth, our cities are being constructed higher and more densely, which creates new opportunities and challenges. One way to make use of the already exploited land could be by using the principle of vertical densification to raise the existing building height and thereby being able to create new housing opportunities. The purpose of this master thesis is to illustrate how a rooftop extension could be configured into an urban environment and what impacts this configuration might have on the microclimate for the subjected area. To study the eligibility for a densification on the selected object, a method of eligibility analysis was carried out. The method used is based on a previous degree project by Larsheim (2007), which deals with stocktaking and assessing property stocks for vertical densification. The redesigned method was before being used on the selected object for densification drafted in consultation with planning architect at Luleå municipality. The final usage of the method resulted in the building being considered suitable for densification. A site analysis was conducted with regards to the existing building and its vicinity with a method written by Thiis-Evensen (1994). The method is focused on describing the architectural nature of the site. This analysis, together with the selected theory of densification and microclimate, was synthesized using Pena and Parshall's (2001) method "Problem seeking", which rendered a suggestion of a program for how the building could be configured. This master thesis resulted in a design proposal for a rooftop extension, see part 6. Gestaltningsförslaget. The extension is located on top of an existing multistory car park building in the centre of Luleå. The rooftop extension contains 45 apartments and consists of three elevated planes that resides on an extended pillar construction. A large green open area on the inner courtyard unlocks new opportunities for an attractive accommodation in the inner city. It also give the residents a room for social play and interaction as well as the opportunity to use cultivable surfaces in a new greenhouse. A microclimate analysis was carried out based on solar, wind, air quality, sound, snow, and the phenomenon of Urban heat islands in order to positively change the impact that might occur when the city’s rooftops are being extended. The analysis carried out influenced the selection of form and material in the design stage for the design proposal presented in part 6. The design proposal presented should be further investigated by another party. The eligibility analysis conducted in this master thesis should be validated and designed in close collaboration with stakeholders and municipalities to ensure that the correct criteria and approaches are being used when the eligibility of the rooftop extension is to be determined.

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Dahlvik, Linn, and Sandra Öster. "Underlag för utformning av nybyggnation i kulturmiljö : En fallstudie i Strömsbro, Gävle." Thesis, Högskolan i Gävle, Samhällsbyggnad, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-30897.

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Idag förekommer bostadsbrist i flera delar av landet. Förtätning kan vara en strategi för att motarbeta bostadsbristen. I miljöer där kulturvärden uppträder finns en viss känslighet för exploatering. Syftet med studien är att undersöka hur förtätning på en fastighet kan anpassas till omkringliggande kulturmiljö och samtidigt bidra till god livskvalitet. Målet är att ta fram kriterier för nybyggnation i kulturmiljö som kan användas som underlag vid exploatering. Ett gestaltningsförslag tas också fram som grundas på de framtagna kriterierna. Arbetet är avgränsat till Strömsbro, Gävle och studien har exemplifierats på fastigheten Strömsbro 37:2 som är lokaliserad i området. För att analysera områdets kulturhistoriska värden och ta fram framtida utvecklingsmöjligheter har DIVE använts som metod. Den utförs i fyra steg: beskriva, tolka, värdera och aktivera/möjliggöra. I analysmetoden har platsbesök och inventering genomförts för att skapa en uppfattning om området och för att identifiera värden. Intervjuer och enkätundersökning har också varit en del av analysen och bidragit till identifiering av värden, förståelse för platsens identitet och för att ta fram möjliga utvecklingar av området. En volymstudie har utförts och ligger till grund för planering av nybyggnation. Beräkning av volymer och exploateringstal i den omkringliggande miljön har tagit fram värden som använts som riktlinjer. Arbetet har tagit fram ett gestaltningsförslag av attraktiva bostäder med hänsyn till kulturhistoriska värden. Gestaltningsförslaget resulterade i två lägenhetshus, ett radhus och en komplementbyggnad som följer traditionell utformning med moderna detaljer. Det framtagna resultatet kan inte representera allas åsikter om bevarande av kulturmiljö, eftersom åsikter och erfarenheter är subjektivt. Subjektiviteten kan uppröra medborgare av den orsaken att kulturmiljö är ett känsligt ämne. Därför bör medborgare involveras i ett tidigt skede av planeringen. Egenskaper i den fysiska miljön som är viktiga vid planering av nybyggnation i kulturmiljö är färgsättning, material, placering av bebyggelse, gatustruktur, taktyp och höjdskala. Dessa kan värderas genom DIVE-analysen. Volymer och exploateringstal är också värdefulla i den fysiska miljön och är viktiga att beakta för att inte påverka kulturmiljön. Gestaltningsförslaget i studien visar hur nybyggnation kan implementeras i kulturmiljö med avseende till framtagna kriterier för att minska inverkan på värdefulla karaktärsdrag.
Today residential shortage occurs in several municipalities in Sweden. Densification could be a strategy to solve this problem. Areas where cultural heritage exists are vulnerable to new construction. The aim of this study is to examine how densification on a property could adapt to the surrounding cultural heritage and contribute to good quality of life. The objective is to form criteria for new housing in a cultural heritage environment as a foundation of exploitation. A visualization proposal has also been designed by the criteria. The study is delimited to Strömsbro in Gävle, Sweden and have been exemplified at the property Strömsbro 37:2 that is located in the area. The method DIVE has been used to analyze cultural heritage values and to demonstrate future development opportunities. The DIVE-analysis is performed in four steps: Describe, Interpret, Valuate, and Enable. By performing site visits and inventory in the analysis, values have been identified and a perception over the area have been obtained. Interviews and questionnaires have also been a part of the analysis and have contributed to identification of values, to understand the sense of place and to clarify possible developments. Building volumes have been studied as another method of this thesis. Calculations of volumes and floor area ratio of the surrounding environment have provided guidelines for the visualization. The work resulted in a design proposal of attractive new dwellings, considering the cultural heritage values and seclusion to reduce unwanted observation to create better qualities of life. The design proposal resulted in two apartment buildings, one townhouse and one complementary building that pursue traditional formation with modern details. The result can not represent everyone’s opinion regarding cultural preservation. Cultural heritage is a sensitive subject and citizens might get upset with the result. Residents should therefore be involved in an early stage of planning. Physical qualities that are important when planning for new housing in a cultural environment are coloring, material, building placement, street network, roofing and height scale. Volumes and floor area ratio are also important in the physical environment. The design proposal in this study shows how new housing could be implemented in a cultural district regarding the criteria.

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Arkåsen, Emma. "Hållbar planering inför framtiden : Förslag till ny bebyggelsestruktur för ett område i Västervik." Thesis, Mittuniversitetet, Institutionen för ekoteknik- och hållbart byggande, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-42692.

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Städer har under sin framväxt planerats på olika sätt. Från rutnätsplaner under 1600-talet till 1900-talets planering som resulterade i sovstäder separerade från arbetsplatserna. När städerna vuxit har de områden som från början låg i utkanten istället hamnat närmare stadens centrum. Gamla industriområden ligger som kilar i stadsbilden och genom att ändra användningen av marken där kan nya bostadsområden växa fram. Dagens forskning visar på att en blandad struktur i bebyggelsen med bostäder, verksamheter och tät gatustruktur är vägen framåt. Är dessutom variationen stor vad gäller typen av bostäder finns det möjlighet att skapa ett område där människor kan trivas över tid och flytta mellan olika bostäder under olika skeden i livet. Studien utreder hur ett område i Västervik, i studien kallat Lärkstaden, kan planeras för framtidens medborgare. Förslaget täcker en yta på 97 000 kvadratmeter som idag innefattar 12 fastigheter, ett koloniområde och grönområden. Här finns idag småskalig industri och handel. Även en del företag inom byggbranschen har sina lokaler i Lärkstaden och den angränsar till bostadsbebyggelse och grönområden. Genom att rita upp ett förslag på ny utformning undersöks vilka funktioner som kan samsas i Lärkstaden och hur bebyggelsestrukturen blir långsiktig. Förslaget förankras i tidigare forskning genom en litteraturstudie. För att få en större förståelse för platsen genomförs ett antal platsbesök och även intervjuer av personer som genom erfarenheter och kunskap bidrar med tankar och idéer.
Cities have been planned in different ways during their growth. From grid plans during the 17th century through 20th-century planning that resulted in quiet parts of the city that lacked life and vitality separated from workplaces. As the cities grew, the areas that were originally on the outskirts ended up closer to the city center. Old industrial areas are like wedges in the cityscape and by changing the use of the land there, new residential areas can emerge. The research today shows that an area with a mixed structure that contains housing, businesses, and a dense street structure is the way forward. In addition, there are great variations in the type of housing that can be constructed to create an area where people can thrive over time and move between different homes during different stages of life. The study investigates how an area in Västervik, in the study called Lärkstaden, can be planned for the citizens of the future. The idea covers an area of 97 000 square meters which today includes 12 properties, a plantation area, and green space. Today there is small-scale industry and trade. Some companies in the construction industry also have their premises in Lärkstaden and it is adjacent to residential buildings and green areas. By drawing up an idea for a new design, an investigation has been carried out showing which functions can be shared in Lärkstaden and how it would become sustainable in the long-term as it will have the required mixed structure mentioned above. The idea is anchored by previous research through a literature study. To gain a greater understanding of the area, visits have been made and people have been interviewed through experience and knowledge offer thoughts and ideas.

Betyg 2021-06-04

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Sohl, Lovisa, and Caps Laura-Marie Svensson. "En studie om dagsljus : Förtätning av staden och dess påverkan på befintliga byggnader." Thesis, KTH, Byggteknik och design, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-276976.

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I Sverige har det funnits en utbredd bostadsbrist under de senaste decennierna och utvecklingen har skett mot större förtätning, målsättningen är att skapa städer med ekonomisk- och socialhållbarhet. Det bortses dock från att tätt planerade städer riskerar att inskränka på dagsljustillgången för de boende. Nordiska klimat med mörka vintermånader och solen som står lågt på himlen skapar en stor utmaning. Forskning visar att god tillgång till dagsljus är viktig för människors hälsa och välbefinnande och det är därför viktigt att skydda dagsljustillgången för boende i svenska städer. Trots detta så är den svenska lagstiftningen för skydd av dagsljus för befintliga bostäder svårtolkad med vaga riktlinjer på vad som kan anses som en rimlig minskning av dagsljustillgång.Denna studie undersöker den aktuella lagstiftningen i Sverige för skydd av dagsljusåtkomst i befintliga byggnader. Med fokus på befintliga bostadshus används resultatet från fördjupade fallstudier över två områden för att undersöka möjligheter för hur en framtida kravställning kan se ut. Förslaget på kravställningen diskuteras med hänsyn till nuvarande praxis.Studiens resultat påvisar att en förtätning av staden i många fall leder till otillräcklig dagsljustillgång i befintliga bostäder och att dagens kravställning för dagsljushantering är bristfällig. Att säkerställa tillräcklig dagsljustillgång i bostäder är nödvändigt redan vid planläggning. Studien visar på ett varierande resultat vid användning av nuvarande föreskrifter och allmänna råd givna av Boverket och den europeiska standarden SS-EN 17037:2018. SS-EN 17037:2018 påvisar ett resultat som är känsligare för förändringar i omgivningen. I kombination med att standarden beskriver den faktiska upplevelsen av ljuset i rummet gör det den till ett lämpligare mätetal för dagsljushantering. Om visionen för framtidens städer ska vara samma som idag bör kravställningen på dagsljus utvecklas.
Over the past couple of decades Sweden has suffered from a housing shortage and the trend towards densification due to ambition of creating cities with economic and social sustainability. It is often missed however that tightly planned cities run the risk of restricting daylight access for occupants. Nordic climates, with their relatively low solar angles and dark winter months pose a particular challenge. An increasing body of research however shows that good access to daylight is crucial to human health and well-being. As such, it stands to follow that protecting daylight access for those living in the city is of great societal benefit. Yet the current Swedish national regulatory structure for protection of daylight access in existing properties gives only vague guidance as to what constitutes an unreasonable reduction of daylight access and/or remedy when an unreasonable reduction in daylight access exists. The resulting uncertainty presents a degree of unwelcome risk to building projects.This study reviews the current state of Swedish legislation for protection of daylight access in existing buildings. With focus on residential buildings it uses results from in-depth case studies to examine possible structures for what a future regulatory framework might look like and discusses the proposal in the context of current Swedish praxis.The study found that in many cases, densification of the city leads to insufficient daylight in existing housing and that today's requirements for natural daylight are inadequate. Ensuring adequate daylight is possible already when planning and should be considered to create a society where human health is secured. The study shows varying results when using current Swedish regulations and the European standard SS-EN 17037:2018. SS-EN 17037:2018 demonstrates a result that is more sensitive to changes in the environment, combined with the standard describing the actual experience of the light in the room making it a more suitable measurement for assessing changes in daylight access for existing properties.

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Kratochvilová, Jana. "Rehabilitace historického jádra a přilehlého okolí města Kyjov se zaměřením na veřejný prostor." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-391836.

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The diploma thesis deals with the construction and activation of the territory in connection with the historical center of Kyjov. Part of the proposal was to work with an existing urban brownfield and an extensive park, which accounts for almost half the area under consideration. The goal, as I set out in my work, is to activate the territory and design an urban sprawl with a suitable functional structure. The proposed design respects the context and character of the site in a modern and sustainable manner. The principles followed in my work are based on the current urban and city-forming rules. I have put an emphasis on the human scale, the priority of pedestrians over traffic, and especially the shortcomings and needs in the territory that arise from the analysis. The draft concept is based on the permeability and interconnection of the individual parts of the city, the insertion of a new public space and the completion of the city block. The new urban sprawl clearly defines the street, completes the boundaries and makes the most of the area on the released land. The newly designed buildings are residential and multi-functional houses with active parterres. Part of the proposal is the revitalization of the city park, which explores its hidden potential. The basic step is to remove obstacles in the permeability of the park and to highlight its strengths, such as the flowing river Kyjovka, healthy large trees and the size of the park itself.

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Forsman, Mona. "Point cloud densification." Thesis, Umeå universitet, Institutionen för fysik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-39980.

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Several automatic methods exist for creating 3D point clouds extracted from 2D photos. In manycases, the result is a sparse point cloud, unevenly distributed over the scene.After determining the coordinates of the same point in two images of an object, the 3D positionof that point can be calculated using knowledge of camera data and relative orientation. A model created from a unevenly distributed point clouds may loss detail and precision in thesparse areas. The aim of this thesis is to study methods for densification of point clouds. This thesis contains a literature study over different methods for extracting matched point pairs,and an implementation of Least Square Template Matching (LSTM) with a set of improvementtechniques. The implementation is evaluated on a set of different scenes of various difficulty. LSTM is implemented by working on a dense grid of points in an image and Wallis filtering isused to enhance contrast. The matched point correspondences are evaluated with parameters fromthe optimization in order to keep good matches and discard bad ones. The purpose is to find detailsclose to a plane in the images, or on plane-like surfaces. A set of extensions to LSTM is implemented in the aim of improving the quality of the matchedpoints. The seed points are improved by Transformed Normalized Cross Correlation (TNCC) andMultiple Seed Points (MSP) for the same template, and then tested to see if they converge to thesame result. Wallis filtering is used to increase the contrast in the image. The quality of the extractedpoints are evaluated with respect to correlation with other optimization parameters and comparisonof standard deviation in x- and y- direction. If a point is rejected, the option to try again with a largertemplate size exists, called Adaptive Template Size (ATS).

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Adlam, Rodney. "Thermomechanical densification of timber : maximising the potential of softwood timber through thermomechanical densification /." [St. Lucia, Qld.], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18520.pdf.

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Nor, Zakaria. "Densification beyond city centres : A socioeconomic investigation of the densification process in Lundby, Gothenburg." Thesis, Umeå universitet, Kulturgeografi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-136161.

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Contemporary urban planning for the past decades has concentrated on sustainable development, for instance through the promotion of dense development (Echenique et al., 2012). Important components for sustainable urban development concerns increasing residential and building density, as means of counteracting the consequences of urban sprawl (Jenks and Jones, 2008). Because it is argued that high-residential density is more economically, environmentally and socially sustainable than low-density since a higher concentration of people contributes to for instance shorter transportation distances as well as makes services and amenities more economically viable (Frey, 1999; Haughton and Hunter, 2004). However, whether the densification of cities has desirable or undesirable social, economic and ecological impacts is highly contested. The purpose of this study is to analyze the socioeconomic outcomes of the urban densification process in the Lundby District, Gothenburg, over time. Through a mixed method approach, statistical information for Lundby District, for the years 2008 to 2015 have been processed and two semi-structured interviews with employees in the City Planning Authority and Lundby District Administration were conducted. The densification in Lundby presents certain strengths, weaknesses, opportunities and threats. As more than 6300 new housing units has been constructed during this time-period, and more is to come in the near future, Lundby experienced a repopulation as the housing construction has facilitate a population increase of more than 11 000 new inhabitants. However, as the favored tenure developed during this time-period been condominiums certain weaknesses exist. Nonetheless, densification and the rapid increase in population has contributed to the number of vehicle per 100 inhabitants decreasing, which presents opportunities for being more environmentally friendly. On the other hand the claim that through densification could diversity and social mixing be achieved is flawed, as seen in Lundby the densification process has brought changes in population structure and socioeconomic characteristics, which suggest some form of gentrification is occurring.

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Madsen, Lynnette D. Carleton University Dissertation Engineering Electrical. "Rapid densification of Borophosphosilicate glass." Ottawa, 1988.

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Zhang, Yi. "Suspension dewatering with aggregate densification." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/suspension-dewatering-with-aggregate-densification(7599d818-8f26-4e2d-b80f-b4fa243dba52).html.

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This thesis concerns design of two pieces of suspension dewatering equipment (i.e. transient batch settlers and steady state continuous gravity thickeners). In a transient batch settler, very slow densification of aggregates within the suspension is considered whilst the drag on the solids in the suspension is assumed to be negligible. The interface of the suspension is then determined by a balance between gravity and the gradient of the compressive yield stress of the gelled suspension. The compressive yield stress functional form in general could be either a weakly gelled formula, or a strongly gelled formula. These formulae differ in the way they behave for solids concentrations in the neighbourhood of the suspension gel point. The effects of the above two gel formulae, the evolution of the compressive yield stress functional form over time during aggregate densification, different initial suspension heights, and different initial feed solids volume fractions upon the predictions of consolidated bed structures and solids volume fractions obtained at the bottom of a batch settler, and upon the evolution of the heights of the suspension and the consolidated bed have been explored. A sufficiently tall initial suspension height might lead to insignificant increases in the solids volume fractions obtained at the bottom of batch settlers after time-dependent aggregate densification. The interfaces of the suspension and the consolidation zone coincide after aggregate densification if the gel point, which increases with time, is larger than the initial feed solids volume fractions. Moreover, the maximum permitted underflow solids fluxes predicted from steady state thickeners have been investigated and compared. Pre-shearing of aggregates which densifies aggregates to have smaller diameters upon entering the thickener is necessary if large underflow solids fluxes and small underflow solids volume fractions are specified. The solids volume fraction at the top of the consolidated bed which is the densified gel point is influenced by the extent of pre-shearing of aggregates. An algorithm for determining this densified gel point has also been developed. In reality, thickeners contain not just a consolidating bed, but also a hindered settling region above it. When the hindered settling region is considered in a thickener, the effects of the extent of aggregate densification that has occurred in the hindered settling region and how that impacts upon thickener performance and sludge rheological properties have been explored in this thesis. A new algorithm for predicting the densified gel point obtained at the top of the consolidated bed has been developed when the hindered settling region is present. The effects of underflow solids volume fractions, aggregate densification rate parameters and pre-shearing of aggregates upon the predictions of maximum permitted underflow solids fluxes, sludge rheological properties, and thickener performance have been explored. The predictions of thickener performance using both the weakly and strongly gelled formulae have also been achieved. In cases where it is possible to neglect the hindered settling region, substantial increases in the maximum permitted underflow solids fluxes, and substantial decreases in the consolidated bed heights and the total solids residence times have been achieved after aggregate densification for a comparatively small underflow solids volume fraction. The benefits arising from aggregate densification are more modest if the underflow solids volume fraction is larger. On the other hand, when the hindered settling region is included, more densification of aggregates occurring in the hindered settling region might lead to taller consolidated bed heights for a specified suspension flux and a specified aggregate densification rate parameter due to higher underflow solids volume fractions.

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Lima, Bruno Avellar Alves de. "A promoção de habitação social por meio da reabilitação de edifícios vazios e subutilizados no Centro de São Paulo: uma abordagem socioambiental." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/106/106132/tde-03112016-131217/.

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O presente trabalho teve por objetivo analisar em que medida a promoção de habitação social por meio da reabilitação de edifícios vazios e subutilizados no Centro de São Paulo contribui para práticas distintas de produção do espaço, até então promotoras de problemas socioambientais associados à lógica periférica de urbanização. A hipótese da pesquisa é a de que a referida medida, apesar de suas limitações, é relevante do ponto de vista socioambiental, corroborando para mudanças na lógica de produção do espaço urbano. A pesquisa foi baseada na revisão da literatura, na análise documental, na realização de entrevistas com técnicas da SEHAB e COHAB-SP, bem como em pesquisa de campo. Apuramos que entre 2000 e 2009 foram entregues pelo poder público 985 unidades de habitação social por meio da reabilitação de 11 edifícios vazios, os quais envolveram os programas PAR-Reforma (federal), PAC-BID (estadual), Provisão Habitacional (municipal) e Locação Social (municipal). No momento atual identificamos 46 edifícios viabilizados no âmbito dos programas Renova Centro (municipal), e Minha Casa, Minha Vida-Entidades (federal), somando um total de 2980 unidades viabilizadas. Trata-se de projetos que possibilitam realizar significativo adensamento nos distritos centrais (em patamares de 2500 hab/ha de densidade líquida média) garantindo o mínimo de inclusão social em projetos dotados de qualidade construtiva e inserção urbana, contribuindo para o adensamento da cidade frente à continuidade de sua expansão difusa, a qual tem historicamente culminado em inúmeros problemas socioambientais. Defendemos que essa alternativa contraria lógicas consolidadas de produção de habitação para as classes de baixa renda, baseadas na produção de unidades novas em conjuntos habitacionais periféricos, ou na autoprovisão da moradia em favelas ou loteamentos informais. Ela representa ainda ganhos ambientais significativos relativos à economia de riquezas naturais que seriam empregadas na construção de novas edificações. Baseados no estudo da recente experiência espanhola, estimamos que o uso dos edifícios atualmente viabilizados representa a prevenção na geração de cerca de 144 mil toneladas de RCDs no caso da opção pela demolição desse estoque, ou do requerimento de ao menos 360 mil toneladas de materiais para a construção do mesmo estoque construído, além da economia de água e recursos energéticos. Em termos de uso de riquezas naturais e emissão de gases do efeito estufa (GEEs), a construção do mesmo estoque médio já edificado acarretaria em requerimentos da ordem de 370 mil a 555 mil toneladas de materiais extraídos da natureza e na emissão de 92.500 a 129.500 toneladas de CO2 equivalente. Tais medidas têm sido limitadas pela prevalência da lógica financeira e sujeição a interesses elitistas, que corroboram com a manutenção das contradições próprias à produção capitalista do espaço.
This study aimed to analyze to what extent the promotion of social housing through the rehabilitation of vacant and underutilized buildings in São Paulo downtown contributes to different practices of space production, hitherto promoting social and environmental problems associated with peripheral logic of urbanization. The hypothesis of the research is that the measure, despite its limitations, is relevant from the environmental point of view, corroborating changes in the urban space production logic. The research was based on a literature review, documental analysis, interviews with employees from SEHAB and COHAB-SP, as well as field research. We found that between 2000 and 2009 its been delivered by the government 985 units of social housing by 11 empty buildings rehabilitation, which involved the PAR-Reforma program (federal), PAC-BID (state) Provisão Habitacional (municipal) and Locação Social (municipal). At the present time we identified 46 buildings made possible under the Renova Centro program (municipal), and Minha Casa, Minha Vida- Entidades (federal), for a total of 2980 units feasible. These are projects that allow achieve significant consolidation in the central districts (at levels of 2,500 inhabitants / ha of average net density) ensuring minimal social inclusion in projects that have construction quality and urban integration, contributing to the consolidation of the city opposite the continuity of its diffuse expansion, which has historically culminated in numerous environmental problems. We argue that this alternative contradicts consolidated logic of housing production for low-income classes, based on the production of new units in peripheral housing estates, or housing of self-provisioning in slums or informal settlements. It still represents significant environmental gains for the economy of natural resources that would be used in the construction of new buildings. Based on the study of the recent Spanish experience, we estimate that the use of currently made possible buildings is preventing the generation of about 144,000 tons of CDWs in the case of option for the demolition of that stock, or the requirement of at least 360,000 tons of materials to build the same stock, in addition to saving water and energy resources. In terms of use of natural resources and emission of greenhouse gases (GHGs), the construction of the same average stock already built would result in requirements of the order of 370,000 to 555,000 tons of materials extracted from nature and issue 92,500-129,500 tons of CO2 equivalent. Such measures have been imitated by the prevalence of financial logic and subject to elite interests, which support the maintenance of the contradictions of capitalist production of space.

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Kopp, Patrizia. "„The Cost of Densification“ : Densification Processes and its Socio-spatial Effects in Santiago de Chile." Thesis, KTH, Samhällsplanering och miljö, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-232725.

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As the title already says the thesis will examine the densification processes and its socio-spatial effects in Santiago de Chile. This thesis has been written in cooperation with a research internship at the Universidad Católica in Santiago at the institute of urban and regional studies. Santiago is the capital of Chile and is a city with one of the highest living standards compared to other South American cities. Santiago, as many other big cities, faces varied problems. Santiago, for example has a rapid population growth mainly through the migration from rural areas and other South American countries (Peru, Colombia, Venezuela). Other problems that Santiago faces are e.g. high resource consumption, air pollution, high number of individual motorisation and lack of green spaces. Especially the smog through the traffic is one of the biggest problems. Due to its location in a valley, Santiago suffers from a lot of air pollution. Santiago needs to further develop and expand its surface for housing. This results in urban sprawl, which has been the past and will be the future development. Through this urban sprawl a lot of residential areas were constructed further outside, on the edge of the city where commuting to the city takes more than 1.5 hours. As people want to live in the urban area of Santiago, they are taking this burden and move outside of the city. Thus the increasing land price makes it harder for low-income people to live closer to the city, as they simply cannot afford living there. Which leads to the topic of this thesis, namely the examination of socio-spatial effects through densification processes will be examined. The scale of the investigation is on a district-level and further research is done on specific building levels. This helps in getting more detailed information, as examining whole Santiago with its different municipalities is difficult and will give a blurry picture on the densification processes. The district, Quinta Normal has been selected for detailed investigation. Quinta Normal lies in the west of Santiago, bordering the district Santiago Centro. With its close proximity to the city centre, good public transport and cheaper land prices than in other parts of Santiago, it is attractive for prospective inhabitants. But due to the constant urban development the land prices are starting to increase as the district gets more attractive through the construction of metro stations. Quinta Normal is challenged by the arrival of high density buildings and new population with different income group. Quinta Normal is described as a district full of life where people established a community, interact and communicate with each other. Is this quality of social life threatened now through the arrival of high densification houses where people who are not originally from Quinta Normal are moving in and changing the structure of the district? Furthermore, there are many effects of segregation and this thesis chose to look at the change of the socio-economic structure in Quinta Normal. The district is mainly inhabited by middle to low-income families. This is a change from previously, when mostly low to very low-income people were living there. Nowadays there is a constant exchange between people moving to and from Quinta Normal. Thus, the future development of Quinta Normal is leading to a bedroom district where people rent an apartment but work in another part of the city. A density calculation has been made, which helps in understanding the effects of different building types on the social structure of the district. The buildings have been evaluated by size of apartment, price, accessibility, green areas, and security in order to give the reader the necessary explanation on the chosen houses and their differences. In summary, this thesis will try to examine the effects of densification processes in Quinta Normal with especially looking at newly constructed residential buildings and how those buildings interact with the existing urban but also social structure. Through a literature review, a characterisation of different types of buildings, a density calculation as well as interviews with the responsible people for the development of the district, an analysis of the effects on the social structure of the district will be attempted.

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Shupe, John. "Densification of nano-sized boron carbide." Thesis, Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/33818.

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Boron carbide nano-powders, singly-doped over a range of compositions, were pressurelessly-sintered at identical temperature and atmospheric conditions in a dif- ferential dilatometer to investigate sintering behavior. Samples that achieved relative densities greater than 93% of theoretical density were post-HIPed. Post-HIPing re- sulted in an increase in relative density as well as an increase in Vicker's hardness. To optimize the sintering behavior, nano-powders with multiple dopants were prepared based on the results of single dopant experiments. These powders were studied using the same heating schedule as the single dopant samples. The powder with optimized composition was selected, and 44.45 mm diameter disks were pressed to determine the effects of sample size. Powder composition #166 with Al, Ti, W and Mg additions was processed using di¢çerent methods in order to create defect-free green bodies after uniaxial press- ing. The 44.45 mm diameter compacts were heat-treated to remove organics and B₂O₃coatings on particles and then encapsulated in an evacuated fused silica am- pule. Encapsulated samples were HIPed at temperatures below the coarsening region observed in the dilatometric traces of multiply-doped nano-powders. The E-HIPed sample showed a relative density of 96% with a limited extent of nano-sized grain microstructure.

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Ibrahim, R. M. "Waste biomass densification for thermochemical conversion." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1563739/.

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Waste biomass densification into briquettes and pellets improves the characteristics of loose biomass residue for efficient transport, storage and thermochemical conversion into advanced fuels (e.g., syngas, for electricity, liquid fuels and chemicals). Briquettes of good and consistent quality are required but often difficult to achieve as more work is still required to understand how the chemical and physical properties of different biomass types, along with process variables, affect their quality. Also, the additional energy and cost associated with biomass briquetting has raised the issue of the sustainability of briquetting loose biomass before its conversion. This research focuses on the use of novel approaches to improve the quality of fuel briquettes for thermal applications, and further evaluates the sustainability of fuel briquetting, using life cycle assessment (LCA). Experiments were conducted to investigate the potential benefits of blending waste rice husks, corn cobs and bagasse, and with novel binders including enhanced treated biosolids, and microalgae (Chlorella sorokiniana), on fuel briquette properties, using factorial design methods. The new binders were also compared with existing starch binder. The range of briquettes produced in this study had unit densities of up to 3.3 times the loose biomass bulk density, and were stronger than briquettes from the individual biomass materials. Considering average values from two biomass sources, an unconfined compressive strength of 176 kPa was achieved at a compaction pressure of 31 MPa for a 3:7 blend of rice husks to corn cobs with 10% binder (starch + water). These briquettes were durable, with only 4% mass loss during abrasion, and 10% mass loss during shattering, tests. They absorbed 36% less water than loose corn cobs. An unconfined compressive strength of 175 kPa was also achieved for a 2:4:1 blend of rice husks, corn cobs and bagasse with 17% binder (microalgae), also at a compaction pressure of 31 MPa. The statistical analysis of the above results showed that the source of the biomass had a significant effect on densification, which emphasises the need to understand factors underlying biomass variability. Of all the briquettes produced with the three binders, those containing the microalgae binder were found to be most durable, with a higher energy density, slower mass loss during briquette combustion, and a higher afterglow time. Since microalgae may be grown using CO2 from biomass combustion, discovery of their advantages as a binder in briquetting is particularly welcome. To evaluate the sustainability of fuel briquetting, a detailed review of the existing LCA studies on fuel briquetting was carried out. These were found to provide insufficient and inconsistent information, due to different choices in system boundary, data sources, functional unit, allocation procedure, briquetting technology and biomass/briquette properties. An LCA model of biomass briquetting was therefore developed to enable transparent comparison of life cycle environmental impacts of briquetting with individual or blends of biomass feeds with a variety of technological options. The main model components include materials and process inventory databases derived from standard sources, main process calculations, user inputs and results sections. The model is open-access in a user accessible format (Microsoft Excel). A representative case study with mixed rice husks and corn cobs showed that the briquetting unit itself made the largest contribution, 42%, to the total life cycle operational energy of the briquetting system. For all the blends of rice husks and corn cobs explored in this study, the total life cycle energy of briquetting was in the range 0.2 to 0.3 MJ per MJ of fuel briquette energy content. Variation of the LCA input parameters in a sensitivity test for the same blend ratios, gave a range of total life cycle energy of briquetting from 0.2 to 1.7 MJ per MJ of fuel briquette energy content. This indicates that energy use in briquetting is not necessarily recovered, highlighting the need for continuous process optimisation and high quality LCA data. An increase in rice husks content of the blend increased the environmental impact of briquetting including the global warming potential (kg CO2-eq), acidification potential (kg SO2-eq), human toxicity (kg 1,4-DB-eq), ozone layer depletion (kg CFC-11-eq), and terrestrial ecotoxicity (kg 1,4-DB-eq) per MJ briquette energy content, as it was associated with a lower briquette density, which increased the energy required for handling.

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Papet, Philippe. "Synthèse et densification de la zircone orthorhombique." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37617287q.

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Loubière, Delphine. "Etude de la densification de suspensions cosmétiques." Bordeaux 1, 1994. http://www.theses.fr/1994BOR10636.

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Les particules minerales de dioxydes de titane (tio#2) sont des pigments frequemment utilises dans les formulations cosmetiques telles que les vernis a ongle. La dispersion de ces pigments est envisageable a l'aide de polymeres, en milieux aqueux et organique. Apres application sur un substrat, les suspensions subissent une concentration en pigments ou densification, en raison de l'evaporation des solvants. Deux themes sont abordes dans ce travail. La stabilite en milieu dilue est etudiee par microscopie optique. Nous avons observe differents phenomenes d'agregation en faisant varier la concentration des polymeres et le ph dans le cas de suspensions aqueuses. En particulier, nous montrons qu'en milieu aqueux, la morphologie des agregats est tres dependante de la concentration en paa. En second lieu, la densification des pigments est caracterisee au moyen des techniques de centrifugation et de compression osmotique. La fraction volumique finale apres densification peut etre correlee aux parametres physico-chimiques initiaux (agregation, adsorption des polymeres aux interfaces)

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Papet, Philippe. "Synthese et densification de la zircone orthorhombique." Limoges, 1988. http://www.theses.fr/1988LIMO0030.

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La zircone pure adopte sous forte pression une structure de symetrie orthorhombique. Le dopage par l'oxyde de niobium nb::(2)o::(5) permet l'obtention directe d'une variete de zircone de symetrie orthorhombique. Par suite de la faible reactivite des melanges en phase solide, deux methodes d'elaboration de poudres par voie chimique ont ete examinees. L'une met en oeuvre un procede sol-gel en milieu organique et l'autre une technique de precipitation simultanee des cations en voie aqueuse

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Klump, Matthew J. "Densification Without Displacement: A Supplementary Housing Strategy." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1553251053967701.

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Cong, Guanglei. "Pico Cell Densification Study in LTE Heterogeneous Networks." Thesis, KTH, Kommunikationsteori, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-103918.

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Heterogeneous Network (HetNet) deployment has been considered as the main approach to boost capacity and coverage in Long Term Evolu-tion (LTE) networks in order to fulfill the huge future demand on mo-bile broadband usage. In order to study the improvement on network performance, i.e. capacity, coverage and user throughput, from pico cell densification in LTE HetNets, a network densification algorithm which determines the placement locations of the pico sites based on pathloss has been designed and applied to build several network models with different pico cell densities. The study has been taken based on a real radio network in a limited urban area using an advanced Matlab-based radio network simulator. The simulation results show that the network performance generally is enhanced by introducing more pico cells to the network.

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Déforet, Maxime. "Croissance et densification d'un épithélium en géométrie confinée." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2012. http://tel.archives-ouvertes.fr/tel-00828161.

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Un épithélium est un tissu formé de cellules étroitement juxtaposées dont la fonction est d'isoler des organes entre eux ou vis-à-vis du milieu extérieur. Nous étudions la croissance d'un épithélium en géométrie confinée. En utilisant des techniques de microfabrication, nous avons développé un protocole de traitement de surface permettant de confiner un tissu dans une zone adhésive pendant plusieurs semaines. La résolution spatiale de cette technique est micrométrique, et nous autorise la conception de motifs adhésifs de diverses géométries. Dans notre étude, leurs tailles sont telles que les cellules s'y comportent collectivement. Nous analysons la croissance d'un épithélium de cellules Madine Derby Canine (MDCK) dans des domaines adhésifs circulaires. La migration et la densification du tissu sont étudiées par PIV (Particle image velocimetry) et d'autres techniques d'analyse d'image. Nous caractérisons les champs de vitesse et observons des oscillations de grande amplitude de la vitesse dont la période correspond à l'hypothèse d'une onde de contraintes se propageant dans l'épithélium. Nous caractérisons également l'apparition d'un bourrelet tridimensionnel de cellules à la périphérie de l'épithélium, rappelant les premières étapes de la tubulogénèse. Dans deux autres expériences, en utilisant une géométrie inverse, nous étudions le recouvrement d'un épithélium sur une région anti-adhésive. Nous montrons que ce recouvrement nécessite un câble d'actomyosine supracellulaire, et que la tension de ce câble s'opposant à une tension de surface définit une taille critique au-delà duquel le motif anti-adhésif ne peut pas être recouvert par l'épithélium

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Kontopoulou, Marianna. "Polymer melt formation and densification in rotational molding." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0034/NQ66215.pdf.

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Steinthal, Michael Gregory 1964. "Laser densification of sol-gel-derived silica coatings." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277183.

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Sol-gel derived silica coatings were deposited on soda-lime-silica by dip-coating. An absorbing metallic layer was sputtered onto the surface of the gel to couple near-infrared radiation from a Nd:YAG laser into the transparent coating. Laser energy was utilized to heat the ceramic coating on a substrate which has a lower glass transition temperature than the coating. Scanning the sample across the beam's path resulted in the formation of a 50 mum wide channel. The characteristics of a channel were altered by varying laser power, sol-gel coating thickness, and scanning speeds. Profilometry and SEM analysis verified that the coating can be heated to high temperatures without damaging the substrate.

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Hogan, Mari 1965. "Chemical synthesis and densification of cesium aluminosilicate powders." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/277275.

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Pollucite (CsAlSi₂O₆) is a refractory phase within the Cs₂O-Al₂O₃-SiO₂. It melts at >1900°C and also has a reported thermal expansion value of 15 x 10⁻⁷/°C. These qualities make it suitable for study as a high temperature structural ceramic. Amorphous powders were synthesized by a novel sol-gel process in the Cs₂O-Al₂O₃-SiO₂ system. Gels were produced from tetraethoxysilane (TEOS), Aluminum chelate, and Cs-acetate. Powders were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), chemical, differential thermal analysis (DTA) and thermogravimetric analysis (TGA). The glass transition and crystallization temperatures were determined to be 945°C and 1026°C, respectively, for the amorphous powders. Pollucite and mullite phases were observed by XRD of bulk glass-ceramics. A density of 3.02 gm/cm³ was observed for the hot pressed material. Dielectric constants in the frequency range 1kHz-1MHz were found to be in the range of 5.23 to 5.78 for the as hot pressed and heat treated samples. Thermal expansion coefficients were also determined.

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Wakefield, R. "Sintering, densification and creep of fine grained mullite." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376067.

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Foster, David. "Densification of silicon carbide with mixed oxide additives." Thesis, University of Newcastle Upon Tyne, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295478.

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Burr, Alexis. "Investigation of pore closure during polar firn densification." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI089/document.

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.La densification du névé en glace est un processus essentiel à comprendre pour interpréter les enregistrements climatiques. Une bonne connaissance des mécanismes permet une datation précise de l'air capturé dans la glace lors de la fermeture des pores. Celle-ci est plus vieille que l'air capturé à cause du transport des gaz dans la colonne de névé plus rapide que la densification de celui-ci. Cette différence d'âge entre la glace et le gaz est généralement appelé le Δage. La densification de la neige consiste en un processus complexe de réarrangement de grains, de frittage et de déformation viscoplastique. Bien que le comportement viscoplastique du cristal de glace soit fortement anisotrope, les modèles de densification actuels ne tiennent pas compte de cette anisotropie. De plus, le caractère granulaire du névé affecte aussi sa densification. La relation entre la fermeture des pores et les mécanismes microstructuraux sous-jacents est encore méconnue. Le but de cette thèse est d'incorporer l'aspect granulaire ainsi que l'anisotropie du cristal de glace dans une approche de modélisation innovante de la densification. Des expériences sur l'indentation viscoplastique de cylindres monocristallins de glace ont été réalisées pour proposer une loi de contact basée sur la théorie de l'indentation, et prenant en compte la déformation préférentielle du cristal de glace sur les plans basaux. Cette loi de contact a été implémentée dans un code utilisant la méthode des éléments discrets pour prédire la densification du névé.La micro-tomographie aux rayons X a été utilisée pour caractériser ex situ le névé polaire en trois dimensions à différentes étapes de la densification (ρ= 0.55-0.88 g/cm3), i.e. pour différentes profondeurs (~23 à 130m). Une étude fine de la fermeture des pores et de différentes caractéristiques morphologiques et physiques a été réalisée pour les sites polaires Dome C et Lock In. Des essais mécaniques ont aussi été réalisés in situ sur du névé extrait de Dome C dans le but de modéliser la densification du névé. Les observations microstructurales des expériences ex situ et in situ révèlent d'importantes différences dues aux vitesses relativement importantes utilisées lors des essais mécaniques. Ces vitesses rapides permettent de découpler la contribution des cinétiques de diffusion de la contribution viscoplastique de la déformation. Les effets de ces contributions sur la morphologie des pores et leurs fermetures sont discutés. Pour caractériser la fermeture des pores, cette thèse propose un indice de connectivité définit par le ratio entre le volume du plus gros pore sur la porosité totale. En effet, cet indice est plus approprié lors de l'utilisation de la tomographie aux rayons X que le ratio de pores fermés pour prédire la densité au close-off
Densification from firn to ice is an essential phenomenon to understand for the interpretation of the climate record. A good knowledge of this mechanism enables the precise dating of the air embedded in the ice. The step at which the air becomes entrapped is the pore closure (or close-off). Because of gas flow in the firn column, the ice is older than the entrapped air. The difference between ice and gas is generally defined as Δage.Snow densification consists of grain rearrangements, sintering and viscoplastic deformation. Although the viscoplastic behaviour of the ice crystal is strongly anisotropic, densification models do not take into account this anisotropy. Firn also bears some granular characteristics that may affect its densification. The interactions between pore closure and microstructural mechanisms in the firn are still misunderstood.The aim of this PhD thesis is to incorporate both the granular aspect of firn and its anisotropy into an innovating approach of firn densification modelling. The mutual indentation of viscoplastic monocrystalline ice cylinders was experimentally carried out to propose a contact law that is based on indentation theory and that takes into account the preferential viscoplastic deformation on the basal plane. We have integrated this contact law into a DEM (Discrete Element Method) code for the prediction of firn densification.3D X-ray micro-tomography was performed on polar firn at different stages of the densification (ρ= 0.55-0.88 g/cm3) and depths (~23 to 130m). A thorough investigation of pore closure and of different morphological and physical parameters was achieved for the Dome C and the newly drilled Lock In polar sites. In addition to these ex situ analyses, in situ X-ray micro-mechanical experiments were carried out on firn extracted from Dome C in order to model its densification. Ex situ and in situ microstructural observations indicate significant differences that can be explained by the relatively large strain-rates imposed to the firn during in situ tests. These large strain rates allow for a decoupling of the effects of diffusion kinetics and of viscoplastic deformation. Their relative weights on the morphology of pores and on their closure are discussed. To measure pore closure, we propose a connectivity index, which is the ratio of the largest pore volume over the total pore volume. We show that this index is better suited for X-ray tomography analysis than the classic closed porosity ratio to predict the close-off density

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Deforet, Maxime. "Croissance et densification d'un épithélium en géométrie confinée." Paris 6, 2012. http://www.theses.fr/2012PA066490.

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Un épithélium est un tissu formé de cellules étroitement juxtaposées dont la fonction est d'isoler des organes entre eux ou vis-à-vis du milieu extérieur. Nous étudions la croissance d’un épithélium en géométrie confinée. En utilisant des techniques de microfabrication, nous avons développé un protocole de traitement de surface permettant de confiner un tissu dans une zone adhésive pendant plusieurs semaines. La résolution spatiale de cette technique est micrométrique, et nous autorise la conception de motifs adhésifs de diverses géométries. Dans notre étude, leurs tailles sont telles que les cellules s'y comportent collectivement. Nous analysons la croissance d’un épithélium de cellules Madine Derby Canine (MDCK) dans des domaines adhésifs circulaires. La migration et la densification du tissu sont étudiées par PIV (Particle image velocimetry) et d’autres techniques d’analyse d’image. Nous caractérisons les champs de vitesse et observons des oscillations de grande amplitude de la vitesse dont la période correspond à l’hypothèse d’une onde de contraintes se propageant dans l’épithélium. Nous caractérisons également l’apparition d’un bourrelet tridimensionnel de cellules à la périphérie de l’épithélium, rappelant les premières étapes de la tubulogénèse. Dans deux autres expériences, en utilisant une géométrie inverse, nous étudions le recouvrement d'un épithélium sur une région anti-adhésive. Nous montrons que ce recouvrement nécessite un câble d’actomyosine supracellulaire, et que la tension de ce câble s'opposant à une tension de surface définit une taille critique au-delà duquel le motif anti-adhésif ne peut pas être recouvert par l’épithélium
Epithelium consists of closely packed cells that make up the inside or outside lining of body’s surfaces. We study the growth of an epithelium in a confined geometry. Using microfabrication techniques, we developed a surface treatment protocol allowing tissue confinement inside an adhesive area over a few weeks. The technique achieves a micrometer resolution and any geometry of the adhesive area is feasible. In our study, the size is such that cells behave collectively. We analyse the growth of epithelium with Madine Derby Canine (MDCK) cells in circular adhesive regions. Migration and densification of the tissue are studied with PIV (Particle Image Velocimetry) and others image analysis techniques. We characterize velocity field and observe large amplitude oscillations of the velocity, whose period match the hypothesis of stress wave propagating through the epithelium. We also characterize the appearance of a tridimensionnal rim of cells at the periphery of the epithelium, similar to the first step of tubulogenesis. In two other experiments, using opposite geometry, we study how the epithelium can cover an anti-adhesive region. We show the covering requires a supracellular actomyosine cable, and the cable tension balanced by a surface tension defines a critical size beyond which the anti-adhesive region cannot be covered by the epithelium

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Dieudonné-Georges, Philippe. "Séchage et densification de gels de silice ultraporeux." Montpellier 2, 1998. http://www.theses.fr/1998MON20008.

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En favorisant l'intensite et la cinetique des reactions de dissolution-redeposition, les proprietes mecaniques de gels de silice sont ameliorees. Un nouveau mode de sechage de ces materiaux est alors propose dans le but d'obtenir des gels secs monolithiques. A partir de la technique de diffusion centrale de rayons x, nous etudions les transformations texturales d'aerogels de silice au cours de leur densification par frittage et par compression. Une analyse des spectres d'intensite diffusee dans les domaines de guinier et porod est effectuee. Elle permet d'evaluer les longueurs de cordes moyennes dans les phases solide et poreuse, la surface specifique, la rugosite de surface, ainsi qu'une taille et une forme des unites elementaires solides. Dans le cas d'echantillons partiellement frittes dont la porosite est inferieure a 50%, une augmentation de l'intensite diffusee est observee aux petites valeurs du vecteur diffusion. Un modele de type scherer rend compte des evolutions texturales observees au cours du frittage. Le flux visqueux s'accompagne d'une augmentation du rayon de la section circulaire des unites elementaires assimilables a des filaments cylindriques. D'autre part, la compression agit essentiellement sur la phase poreuse du materiau. La phase solide n'est pas affectee par ce processus, a l'echelle des unites elementaires. L'etude de la texture poreuse des aerogels partiellement densifies est egalement realisee a partir de la technique d'adsorption-desorption d'azote.

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Nivot, Christelle. "Densification de l'alumine : frittage sous pression de gaz." Saint-Etienne, EMSE, 2004. http://www.theses.fr/2004EMSE0029.

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Le frittage sous pression de gaz est généralement utilisé pour améliorer la densification de matériaux thermodynamiquement instables aux températures de frittage classiques. L'objectif de ce travail est d'étudier la stabilité de la porosité issue du frittage de l'alumine sous pression d'un gaz insoluble : l'azote. En observant les conséquences sur la densification et la microstructure de comprimés d'alumine frittés sous différentes pressions d'azote (entre 2 MPa et 6 MPa), il s'avère que l'effet de la pression se manifeste principalement au cours du stade initial du frittage en retardant la formation des cous entre les grains. En revanche, la fermeture de la porosité et le grossissement des grains ne sont pas modifiés par la présence d'azote sous pression. Jusqu'à une densité relative finale d'environ 95%, la comparaison avec des modèles de la littérature met en évidence une densification contrôlée par la diffusion aux joints quelle que soit la pression d'azote appliquée au cours du frittage. Par ailleurs, cette étude a mis en lumière la nécessité d'une représentation de la taille des grains en fonction de la densité relative. L'existence d'une trajectoire unique de frittage : diamètre des grains = f(p), a conduit à une optimisation du cycle de relachement de la pression en fin de cycle thermique de manière à s'écarter de cette trajectoire de frittage. La contrainte de frittage élevée que présentent les matériaux frittés sous pression est mise à profit de manière à obtenir des matériaux denses à grains fins
Gas pressure sintering is usually used to improve densification of compounds which are thermodynamically unsatble at typical sintering temperatures. The aim of this work is to study stability of pores performed in alumina materials by applying a nitrogen pressure during sintering cycle results on densification and microstructure evolution show that a nitrogen presure (between 2 MPa and 6 MPa) mainly delays necks formation and consolidation during initial stage of sintering. Indeed, pore closure and grain growth are not altered by nitrogen pressure during intermediate and final stages of sintering. Up to final relative densities of about 95%, modelling comparison points out densification controlled by grain boundaries diffusion whatever the pressure applied. Furthermore, this study underlined the importance of grain size evolution plotted versus relative density. This representation : average grain size = f(p) shows the existence of a unique sintering trajectory for any nitrogen pressure applied. A depressurization cycle optimization revealed that it's possible to obtain another sintering trajectory which translates the capability of materials to continue densification after depressurization without grain growth

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ZAGOURI, DIDIER. "Densification superficielle de matériaux poreux par choc-laser." Poitiers, 1992. http://www.theses.fr/1992POIT2331.

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Au cours de cette etude nous avons developpe un traitement de surface des materiaux poreux destine a ameliorer leurs proprietes mecaniques. Le principe est d'obtenir un compactage superficiel du materiau sous l'effet d'une onde de choc generee par un laser impulsionnel de puissance. Le comportement des milieux poreux sous choc est decrit a l'aide de divers modeles qui ont ete introduits dans le code de simulation numerique shylac, dans le but de prevoir les effets du choc et d'analyser les resultats experimentaux ulterieurs. Nous avons ainsi montre que les caracteristiques de la detente du milieu apres choc sont determinantes sur la profondeur densifiee. L'etude experimentale a ete effectuee, principalement sur des echantillons d'acier fritte a interet industriel, afin de mettre en evidence l'influence de la porosite initiale du materiau et des conditions d'irradiation (intensite incidente, duree de l'impulsion) sur le compactage. Apres traitement laser d'un echantillon, le profil de densification est determine par analyse d'image. Les profils experimentaux sont bien reproduits par les simulations numeriques

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Saczek, Ted. "Over Growth: a metabolic densification of Cape Town." Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/22944.

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Contemporary cities are experiencing unprecedented growth to cater for growing populations and immigration into urban centres. As a result cities are becoming increasingly densified especially in developing countries2. Densification, and the associated growth, provides many social and cultural benefits, but can lead to increased pollution, environmental degradation, the destruction of existing urban fabric, a lack of greenery, a lack of light to street level, unmanageably large, decaying buildings and increased pressures on infrastructure. This dissertation argues that the design of densified spaces is of utmost importance if we are to maintain a healthy operating space for humanity and the planet. Since before the industrial revolution our society has become governed by a mechanistic way of thinking that originates from technology and science. These thought patterns have shaped the way we design and perceive architecture globally. Many other aspects of society are also influenced by the same mechanistic thought, including our global economic system. This system focuses on indefinite growth; a goal that our finite planet cannot sustain. This paradigm suggests that new, complex approaches to city growth need to be considered to avoid impending disasters. Over Growth investigates various biological concepts that can be applied to densification. Metabolism is used to understand how Cape Town can become more socially and ecologically sound. It suggests that to retain its local character and multi-cultural identity new buildings should grow over valuable, existing urban fabric. The cell is used to interrogate basic increments of city growth. These range from from the scale of an urban block, to individual ERF sizes and to the basic units of the proposed architecture. Symbiosis suggests that cities can exist in harmony with the natural environment. City growth, as an organic process, facilitates the necessary shift away from rational, dualistic thinking towards more complex solutions. These ideas are applied to the South African context, and in particular, a site on Bree Street. Many cities in the developing world continue to aspire to the western models of development. The development of Cape Town is thus threatened by the predominant mechanistic worldview. Conversations with Gawie Fagan, an architect and occupant of the chosen site, gave insight into the city's future and its past, explained later. In general this process was open, collaborative and interdisciplinary to be congruent with the push towards complexity over mechanistic thinking. In short, I develop an approach to architecture that could most suitably alleviate the negative affects of densification in central Cape Town. These include: the deconstruction of spatial hierarchies by using the idea of cellularity to create a more diverse, inclusive social realm; the adaptation, configuration and tectonic of cells; the provision of structure, services and greening to accommodate future additions in a layered 'over growth' that is simultaneously occupied and under construction; and the malleability of the city's zoning regulations and its densification strategy.

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Boxill, Lois E. C. "Foundation remediation of existing structures using ground densification methods." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/21792.

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Ma, Jan. "Constitutive modelling of the densification of porous ceramic components." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286645.

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Partridge, Jonathan Koert. "Experimental studies of liquefaction and densification of liquid oxygen." Master's thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4574.

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Rocketry employs cryogenic refrigeration to increase the density of propellants, such as oxygen, and stores the propellant as a liquid. In addition to propellant liquefaction, cryogenic refrigeration can also conserve propellant and provide propellant subcooling and densification. Previous studies analyzed vapor conditioning of a cryogenic propellant, which occurred by either a heat exchanger positioned in the vapor or by using the vapor as the working fluid in a refrigeration cycle. This study analyzes the refrigeration effects of a heat exchanger located beneath the vapor-liquid interface of liquid oxygen. This study predicts the mass liquefaction rate and heat transfer coefficient for liquid oxygen using two different models, a Kinetic Theory Model and a Cold Plate Model, and compares both models to experimental data. The Kinetic Theory Model overestimated the liquefaction rate and heat transfer coefficient by five to six orders of magnitude, while the Cold Plate Model underestimated the liquefaction rate and heat transfer coefficient by one to two orders of magnitude. This study also suggested a model to predict the densification rate of liquid oxygen, while the system is maintained at constant pressure. The densification rate model is based on transient heat conduction analysis and provides reasonable results when compared to experimental data.
ID: 029049996; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.M.E.)--University of Central Florida, 2010.; Includes bibliographical references (p. 127-129).
M.S.M.E.
Masters
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering

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Benigni, Camille. "Les espaces intermédiaires et la densification des tissus périurbains." Thesis, Paris 10, 2014. http://www.theses.fr/2014PA100147/document.

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Le débat actuel, portant sur la consommation des territoires qui est associée à la périurbanisation caractérisée par la maison individuelle, nous a amené à entreprendre notre travail. La volonté d’inscrire l’évolution des tissus périurbains dans une historiographie architecturale et urbaine nous a conduit à analyser ces formes périurbaines, à travers l’étude des processus et mécanismes morphogénétiques. La densité a eu mauvaise presse auprès des scientifiques et professionnels de la ville, aujourd’hui celle-ci semble être considérée comme un remède à l’étalement des territoires. Ainsi, nous nous sommes intéressés à l’instrumentalisation de la densité par les différents acteurs de la Ville, à travers les lois, les documents d’urbanisme. Nous nous sommes penchés sur l’étude de la définition de la densité, de sa place dans la théorie urbanistique et du rapport qu’elle entretient avec la morphogénèse des tissus périurbains. Ce travail aborde la transformation des tissus périurbains (dont l’analyse est peu présente dans les travaux scientifiques) au travers du prisme des espaces intermédiaires, que nous considérons comme un enjeu important dans l’évolution durable des territoires. Enfin, ce travail s’est proposé de réaliser une nouvelle lecture des espaces périurbains par les espaces intermédiaires à l’échelle de la parcelle pavillonnaire, en considérant que l’analyse des transformations, qui s’y déroulent, représente un élément marquant/discriminant pour l’élaboration des politiques urbaines
Actually the discussion about the use of territories, which is associated with suburbanization characterized by the house led us to undertake our research. The research aims to include the development of peri-urban fabrics in architectural and urban historiography. And from that, we have analysed these suburban forms. Density has a bad press among scientists and city professionals; today it seems to be considered as a cure for the urban sprawl. Therefore, we have looked at the exploitation of the density by the different actors of the City, through legislation, planning documents. We focused on the study of the definition of density, its place in urban theory and its relation with peri –urban fabric morphogenesis. This research addresses the transformation of suburban fabric (whose analysis is not present in the scientific work) through the prism of the “in-between spaces”, which we consider an important issue in the sustainable development of territories. Finally, this work has proposed to produce a new reading of suburban areas by the “in-between spaces” in the suburban plot, whereas the analysis of the transformations that take place, are a prominent feature for urban policy

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Zhang, Xiaoli. "Advanced densification methods of BaZrO3-based proton conducting materials." Master's thesis, Universidade de Aveiro, 2009. http://hdl.handle.net/10773/2298.

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Mestrado em Ciência e Engenharia de Materiais
Materiais de BaZrO3, dopado com Y apresentam boa estabilidade química e mecânica e elevada condutividade protónica o que torna possível a sua aplicação como SOFC a temperaturas intermédias. No entanto, para no futuro, poderem serem utilizados como condutores protónico eficazes, há vários obstáculos que têm de ser ultrapassados, como a baixa sinterabilidade ou a elevada resistência na fronteira de grão. Foram estudados potenciais aditivos de sinterização, entre os quais, H3BO3, BaB2O4, (NH4)H2PO4, H3PO4, Zn(NO3)2, ZnO, e BaCl2, e analisado o seu efeito na sinterização e microestrura. Por adição de H3BO3, a densificação da amostra cerâmica de BaZrO3 iniciou-se a temperatura mais baixa quando comparada com a amostra sem aditivo e a densificação obtida atingiu os 97%. Independentemente do tipo de solução utilizada, os aditivos H3BO3 e BaB O 2 4, não se revelaram eficazes para a densificação da amostra cerâmica de BaZr0.85Y0.15O3. Investigação do parâmetro de rede indicou que os fases Ba3B O or YBO +BaCO , B2 6 3 3 com altas temperaturas de fundação, podem formar. TGA supportou a ideia que o fase YBO3 forma.A utilização de P 5+ como aditivo de BZY15 não conduziu à diminuição da temperatura de início da sinterização ou a um aumento da densidade após sinterização. A distribuição homogénea de Zn em BZY15 conduz a um acentuado e relativamente uniforme crescimento de grão, que, por sua vez, resulta em densificaçãoes elevadas (>90%) por adição de 4mol% de Zn. Na ausência de fases líquidas, sugere-se que a densificação tenha lugar através da difusão das partículas no estado sólido. Com base nos ensaios realizados, concluiu-se que a adição de BaCl2 não é suficiente para um aumento eficaz de densificação. ABSTRACT: Y-doped BaZrO3(BZY) materials show good chemical and mechanical stability and high proton conductivity which is sufficient for intermediate temperature SOFC application. But there are several barriers for Y-doped BaZrO3 to overcome before it can be implemented as a protonic conductor electrolyte material in the future. These are, poor sinterability and high grain boundary resistance. In this thesis work, we aim to improve the sinterability of BaZr0.85Y0.15O3 (BZY15) materials by adding sintering additives. Several potential sintering additives were studied, which are H3BO3, BaB2O4, (NH4)H2PO4, H3PO4, Zn(NO3)2, ZnO, and BaCl2, both densification behavior and microstructure were examined. By adding H3BO3, densification of BaZrO3 (BZO) material was dramatically improved. Doped samples showed lower sintering starting temperature and much higher sintered density (97% that of theoretical density) compared with undoped BaZrO3. Regardless of the solution type, H3BO3 and BaB2O4 did not work as sintering aids for BaZr0.85Y0.15O3-δ. Lattice parameter analysis and indicates that high melting temperature phases Ba3B O or YBO +BaCO B2 6 3 3 were likely formed during sintering. TGA analysis reinforces the suggestion that the YBO3 phase forms. The use of (NH4)H2PO4, H3PO4 and BaCl2·2H2O as additives in BZY15 did not allow a decrease of sintering starting temperature or an increase of sintered density, highlighting the failure of them to be sintering additives for BZY15. Zn added BZY15 showed enhanced densification and relatively uniform grain growth of the host oxide. Despite better wetting of the grains and high intergrain contact in the methanol solution doped cases, slightly lower densities are obtained than in the ball milled case due to the presence of large pores. In the P-doped and Zn-doped compositions, the addition of sintering additives by solution doping leads to large pores due to precursor decomposition, lowering final densities.

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Hunt, Michael Patrick. "Pressureless Densification of Alumina - Titanium Diboride Ceramic Matrix Composites." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/31326.

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The research focus was to determine diffusion mechanisms responsible for densification behavior of SHS produced Al2O3/TiB2 Ceramic Matrix Composites (CMCs). Previous research has shown SHS produced Al2O3/TiB2 composites exhibited unique microstructural properties that contributed to high strength, fracture toughness, and hardness properties. Pressureless densification of SHS produced Al2O3/TiB2 composites would provide a cost savings because the equipment for pressureless densification is less expensive and less complicated than equipment required for densification with pressure. Models for sintering of CMCs and calculation of Sintering Time Constants (STC) were used to predict the densification behavior of the SHS produced Al2O3/TiB2 composite. The Levin, Dirnfeld, Shwam equation was used to determine the Rate Controlling Diffusion Mechanism (RCDM) and activation energy for sintering. X-Ray Diffraction (XRD) analysis of the as-milled reaction product powder revealed the presence of an aluminum borate (Al18B4O33) as a third phase, as well as, in pressureless heat treated samples. Based on experimental results and analysis, it seemed possible the Al18B4O33 compound may have formed by reaction of Al2O3 with TiB2 along their interfaces. Aluminum borates have been observed to form Al18B4O33 (s) + B2O3 (l) at temperatures above 1000Â°C. The RCDM for densification of SHS produced Al2O3/TiB2 was found to be liquid phase diffusion with volume diffusion also likely being active during densification. In addition, Al18B4O33 seemed to be the preferred compound formed during oxidation. Further research should be performed to control formation of Al18B4O33; as well as, on the oxidation behavior of the SHS produced Al2O3/TiB2.
Master of Science

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Kuo, Cheng-Hua. "Densification of Non-Reactive Viscous Liquids Containing Solid Inclusions /." The Ohio State University, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487930304685544.

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Söderholm, Dennis. "Rural Densification and the Linear City : a Thought Experiment." Thesis, KTH, Urbana och regionala studier, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-188889.

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Densification of the urban structure is a hot topic in urban development, but densification is almost absent as a strategy in rural settlements. This project studies densification in a rural settlement in a Nordic context by using the "dense and low-rise" design strategy and the concept of linear cities. Is linearity the key to rural densification? The concepts are tested on the small town of Kimito in south-western Finland.

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Philippe, Pierre. "Etude théorique et expérimentale de la densification des milieux granulaires." Phd thesis, Université Rennes 1, 2002. http://tel.archives-ouvertes.fr/tel-00001818.

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Cet exposé aborde le problème de la compaction granulaire par différentes approches complémentaires. Cette densification lente d'un empilement de grains sous sollicitations répétées s'inscrit dans le cadre d'une analogie conceptuelle avec les systèmes vitreux. Nous développons tout d'abord une modélisation numérique capable de simuler cette relaxation lente et de retrouver toute la phénoménologie expérimentale. Cet outil offre en particulier la possibilité d'une analyse statistique de l'espace des pores et de son évolution. Grâce à des dispositifs expérimentaux variés, nous avons mené une étude détaillée de l'effet de secousses verticales sur un empilement de billes. L'effet à court terme est observé à travers la réponse dynamique à une seule secousse. A l'échelle de l'empilement, la dissipation se révèle quasiment instantanée tandis qu'au niveau plus local, de petits événements sont observés sur des temps beaucoup plus longs. Pour des séquences de secousses sur le long terme, les empilements statiques étudiés relaxent lentement vers un état stationnaire final. Cette densification est très bien approchée par une loi fréquemment utilisée pour décrire la relaxation des systèmes vitreux. Une relation de type Arrhenius relie le temps caractéristique de compaction et l'accélération des secousses qui joue ici un rôle équivalent à une température. Parallèlement à la compaction, une convection d'ensemble est observée et, bien que très limitée, elle peut avoir des conséquences notables aux temps longs. De façon générale, une augmentation du frottement aux parois ou une diminution de l'écartement latéral ralentissent la dynamique de la compaction comme de la convection. Par ailleurs, les deux phénomènes continuent de se manifester au-dessous du seuil de décollage de l'empilement. De petits événements localisés peuvent donc, à terme, amener à une restructuration globale très nette.

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Olivi-Tran, Nathalie. "Simulations numériques des mécanismes de densification des aérogels de silice." Montpellier 2, 1995. http://www.theses.fr/1995MON20171.

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Les aerogels de silice sont des materiaux de grande porosite qui representent un bon support pour les etudes theoriques. On a tout d'abord resume les connaissances sur la structure des aerogels ainsi que sur les modeles representant ces materiaux. On a aussi analyse le processus de frittage sur des materiaux en general et sur les aerogels de silice en particulier. La densification des aerogels qui conduit a l'elaboration des verres est modelisee par deux methodes: l'habillage et le pavage. Les proprietes telles que les limites inferieure et superieure de domaine fractal et la surface specifique sont calculees en fonction de la densite des aerogels partiellement densifies. On obtient des lois d'echelle qui dependent de la dimension fractale. On a aussi etudie la structure poreuse des aerogels au cours de la densification et la diffusion aux petits angles sur ces materiaux. Enfin, on a etudie l'evolution d'agregats fractals bidimensionnels par flux visqueux et par diffusion de surface. Les limites inferieure et superieure de domaine fractal ainsi que la longueur du perimetre du contour des agregats ont ete calculees en fonction du temps. On en a deduit des lois d'echelle qui dependent de la dimension fractale

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Rovillain, Dominique. "Procédé de densification rapide et caractérisation de composites carbone/carbone." Bordeaux 1, 1999. http://www.theses.fr/1999BOR10536.

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L'etude porte sur la comprehension d'un procede de densification rapide de composites carbone/carbone a partir d'un precurseur liquide. Sur une premiere installation de type pilote a chauffage inductif, l'influence de la temperature et des precurseurs, essentiellement aromatiques et aromatiques monohalogenes, a ete regardee. Les nouveaux precurseurs conduisent a une cinetique plus rapide et a un meilleur rendement en carbone, a un pyrocarbone toujours de texture laminaire rugueuse, polynucleee dans le cas des precurseurs halogenes, mais legerement plus desoriente que le cas du cyclohexane. Avec la realisation d'installations a l'echelle du laboratoire, nous avons pu explorer les mecanismes mis en jeu dans le procede par une mesure de la vitesse de depot observee sur un monofilament de 7 m de diametre par microscopie optique, et faire une etude de l'influence du mode de chauffage (resistif/inductif). Un modele simple permet a partir des donnees experimentales de remonter a une approximation des gradients thermiques dans la zone de densification en reliant la vitesse de depot sur les fibres et la vitesse de densification. Un second modele traite de la propagation du front de densification et est base sur la theorie asymptotique des flammes premelangees.

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Rijal, Binod. "Combined Effect of Densification and Pretreatment on Cellulosic Ethanol Production." Thesis, North Dakota State University, 2012. https://hdl.handle.net/10365/26730.

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Biomass densification enhances material stability, improves flowability, and decreases both handling and transportation costs. The effect of densification, before or after pretreatment, was tested to determine the effect on cellulosic ethanol processing. Pelleting increased glucose yields of non-pretreated materials by 210% and pelleting followed by acidic and alkaline pretreatments had significant positive impacts on hydrolysis rates or yields. The increase in sugar yields was attributed predominantly to grinding of biomass within the pellet mill. The effects of low pressure densification following AFEX pretreatment were tested under several enzyme loadings both with and without prolonged storage. Densification had no adverse effects on ethanol yields from switchgrass or corn stover; however, prairie cordgrass yields were reduced by 16%. High enzyme loading (15 FPU/g-glucan) produced 15-20% higher ethanol yields than low enzyme loading (5 FPU/g-glucan). Biomass storage by 6-months did not have any negative effects on ethanol yields of AFEX-treated and densified biomass.

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Vranckx, Alexander. "Effect of heterogeneous densification due to vibroflotation on liquefaction resistance." Thesis, KTH, Jord- och bergmekanik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-208082.

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Desplat, Olivier. "Etude d’un procédé innovant de densification de poudres de bauxite." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEM030.

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La bauxite est un minerai utilisé pour l’élaboration de l’aluminium ou en tant que matière première pour les ciments techniques. Elle est employée, sous sa forme naturelle, en blocs. Ces blocs se font de nos jours de plus en plus rares et leur manutention peut entraîner des pertes sous formes de poussières non valorisées. L’objectif de ce projet est de recycler ces fines particules minérales sous forme de compactés afin d’améliorer l’usage des ressources naturelles minérales qui se raréfient. Ces compactés sont obtenus par compression directe puis avec un procédé innovant couplant vibration et compression. La poudre de bauxite est mélangée à du ciment et de l’eau, puis subit une phase de compaction. Ces compactés doivent avoir des propriétés spécifiques en termes de masse volumique, porosité et résistance mécanique. La micro-tomographie à rayons X est utilisée pour décrire le réarrangement granulaire et l’homogénéité 3D des porosités. La distribution poreuse est caractérisée par analyse d’image et comparée avec les résultats de porosimétrie mercure. Cette étude concernant l’évolution des paramètres texturaux des compactés amène une compréhension des phénomènes liés à la phase de compression. Le stockage et la maturation de ces compactés sous température et humidité contrôlées ont également été étudiés. L’optimisation des paramètres de compression et de formulation, comme la quantité d’eau ou de ciment dans le mélange et la pression de compression, a mené à l’amélioration des propriétés des compactés. Dans un second temps, la phase de compression et les propriétés des compactés ont été améliorées en utilisant une phase préliminaire de vibrations. Cette phase a été optimisée grâce à l’étude de plusieurs paramètres spécifiques comme le type, l’amplitude et la fréquence des vibrations
The bauxite is used in aluminium elaboration or directly as a raw material for calcium aluminates in technical cements. It is used, as a raw material, as blocks. Recently bauxite blocks are rarer and rarer and their handling can lead to dust wastes that are not re-used. The objective of this project is to recycle the fine mineral particles in compacts to improve the use of natural mineral resources that are running out. These products are compacted by direct compaction and also with an innovative vibration and compaction process. The bauxite is mixed with cement and water, and then the mixture is compacted. They must have specific properties with higher density and mechanical resistance. X-Rays micro-tomography is used to describe the particle rearrangement and the 3D density homogeneity. The porous distribution is then characterized by image analysis and compared with the mercury intrusion porosimetry results. This study on textural parameters evolution of the compacts leads to improve an understanding about the phenomenon during the compaction stage. The storage with controlled temperature and humidity will also be studied. The optimization of the compression and mixture parameters, as amount of water or cement in the mixture and compression pressure, led us to get compacts with improved properties. In the final study, we improved the compression stage and the compacts properties by another stage using in-situ vibrations. The vibrations stage has been optimized studying several vibrational parameters especially the type, the duration, the amplitude and the frequency of the vibrations

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Bolouri-Bazaz, Jafar. "Sand subject to biaxial cyclic loading." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391711.

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Patel, Jaydeep Kantilal. "The role of mixed additives in the densification of silicon nitride." Thesis, University of Newcastle Upon Tyne, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357763.

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Souza, Guilherme Parente. "Densification behaviour and microstructural evolution of a red clay-based stoneware." Thesis, University of Sheffield, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427183.

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