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In many practical imaging scenarios, including computed tomography and magnetic resonance imaging (MRI), the goal is to reconstruct an image from few of its Fourier domain samples. Many state-of-the-art reconstruction techniques, such as total variation minimization, focus on discrete ‘on-the-grid” modelling of the problem both in spatial domain and Fourier domain. While such discrete-to-discrete models allow for fast algorithms, they can also result in sub-optimal sampling rates and reconstruction artifacts due to model mismatch. Instead, this thesis presents a framework for “off-the-grid”, i.e. continuous domain, recovery of piecewise smooth signals from an optimal number of Fourier samples. The main idea is to model the edge set of the image as the level-set curve of a continuous domain band-limited function. Sampling guarantees can be derived for this framework by investigating the algebraic geometry of these curves. This model is put into a robust and efficient optimization framework by posing signal recovery entirely in Fourier domain as a structured low-rank (SLR) matrix completion problem. An efficient algorithm for this problem is derived, which is an order of magnitude faster than previous approaches for SLR matrix completion. This SLR approach based on off-the-grid modeling shows significant improvement over standard discrete methods in the context of undersampled MRI reconstruction.

Off-grid houses in the United States are often connoted with mostly non-professional, home-made structures and isolated, hippie living in remote rural areas. These off-grid homeowners may also complete their consumer-independent commitment with a minimal-waste, land-dependent lifestyle that includes methodical harnessing and recycling of resources and materials, raising livestock, and productive gardening on the property. This research paper explores the background, methods and kinds of typical off-grid living structures, their ability to harness natural resources for function and performance, and the ability of its occupants to remain resilient in the face of depleting fuel resources, extreme weather patterns, and rising costs of living. The goal of this research is to propose modern and resilient off-grid housing design to exist as normalized, micro-communities within typical suburban communities in the United States. The housing prototype, sited in Dudley, Massachusetts, optimizes passive resources for heating and cooling thermal comfort, prefabricated materials for construction, and modern technology for inhabitation. Its hyper-local design incorporates building science that integrates researched techniques and philosophies from current movements of sustainable design in the United States and Canada, such as Passive House, Net Zero, LEED, and the Living Building Challenge.

V diplomové práci je krok po kroce vypracováno řešení zabezpečení energetického zdroje pro typické město v Sibiřské oblasti. Data, která tvoří zadání, byla získána od zákazníka pomocí dotazníku, protože pro nás oblast v čase vypracování nebyla dostupná. Na základě informací o aktuální energetické situaci, obyvatelstvu a dřevospracujícímu průmyslu je vybrána vhodná technologie pro zabezpečení tepla a elektrické energie. Druh zdroje byl vybrán dle dostupného paliva a následně byl proveden výpočet a design en- ergetického zdoje založeného na Rankine Clausiovém cyklu. Řešení obsahuje technický i ekonomický návrh. Technické řešení ukázalo, že nejdůležitější parametry jsou spolehlivost, bezpečnost a jednoduchost řešení. Design sítí, přídavných zařízení a plánování údržby není obsahem této práce. O dalších projektových krocích pojednává závěr.

In an age where the sharing economy has proliferated as a preferred means of travel in the tourism industry, and the accommodation sharing platform Airbnb has risen to the forefront, there is much criticism and discussion about the need for such nascent platforms to operate in alignment with sustainable development. Currently, economic benefits for the host and guest lie at the core of Airbnb’s sustainability appeal, while few concrete steps have been taken to advance environmental and social values. Many have proposed a green rating system and sustainability-oriented search filters as a means to propagate these values and catalyze a necessary paradigm shift within the sharing economy. Through the lens of green architecture and construction, this study analyzes the extent and manner in which sustainability features and amenities are promoted by hosts on Airbnb in the high-desert mountain town of Taos, New Mexico. This case study approach selects and intriguing destination that is not only characterized by a long history of earthen building traditions by the Tiwa people, but was also the birthplace of the world-renowned, off-the-grid Earthship concept. An analysis of all active Airbnb listings was compared with a more targeted analysis of off-the-grid listings to reveal that hosts more often than not frame their sustainability features and amenities in terms of visitor comfort, convenience, and enjoyment. For instance, the valorization of earthen adobe building for its authenticity and cultural appeal in lieu of its energy efficient and natural qualities. This indicated a high level of unexploited potential, wherein hosts could enhance their listing’s sustainability appeal and educational value through reframing these features to potential guests, and off-the-grid listings could benefit from implementing and promoting sustainable practices and emphasizing the local culture. Most importantly, after quantitively analyzing the features that arose, this study assembled the content basis for a theoretical green rating system and sustainability search filters that could be applied to Taos as a localized system, or merely provide insight to other destinations and the Airbnb platform as a whole.

Over the past decade, technologies that facilitate household electricity production and storage have seen a rapid development along with a significant cost reduction. Research points to an increased share of household-produced electricity within the existing national grids across the globe. In some cases, self-sufficiency is possible where households are able to decouple from the grid and become independent on their electricity, in other words, go off-grid. Furthermore, this change puts additional pressure on how the electricity system is set up, which, challenges prevailing incumbents to adapt. Depending on the geographical location, circumstances for selfsufficiency varies. Sweden is a country with high seasonal variations with its Northern position, which raises the question of how off-grid households are feasible and, how they can receive traction. To investigate possible changes within large technical systems such as the electricity system, which is a vital part of the society, theories within socio-technical systems have shown much promise. However, these theories often lack the more techno-economic aspect of concrete and future investment costs from a consumer perspective, suggesting an existing research gap. Hence, the purpose of this study is to provide further knowledge regarding off-grid applications in the Swedish Context. This is done by investigating what circumstances could trigger existing electricity consumers to go off-grid. The research process and structure of the report can be interpreted as indiscriminate, however, the study has focused on combining theories surrounding socio-technical changes whilst applying techno-economic modelling to strengthen the work, similar to a dual paper study. Data was collected in the form of a literature review and interviews to provide a holistic representation of off-grid and its nexus to the electricity system. In addition to this, complementing modelling of grid-connected-, prosumer-, and off-grid households were performed. Results point towards a scene where off-grid reaches grid parity within the coming two decades, which, will increase the economic rationale of investing in an off-grid. Opposingly, there is currently no economic rationale in off-grid applications considering the relatively low electricity costs in Sweden as of today. Moreover, conditions show promise if the adopters see beyond economics and, possesses a strong will towards independence. However, implications suggest that the high reliability and low costs of the Swedish electricity grid impedes the ability of new radical innovations to receive traction. Furthermore, this study has contributed by filling the research gap between socio-technical changes and techno-economic projects in regards to electricity systems. Consequently, contributing to the academic field of socio-technical change, it has been shown that the combination of socio-technical change and techno-economic projections is applicable and beneficial. Additionally, it can be argued that the results of this study highlight that the consumer have a greater role in the development of off-grid applications than what the theories suggest. Lastly, the electricity system is a complex mechanism and, to further strengthen the perception of how a relatively new application, as in the case of off-grid, will impact the system, appurtenant suggestions for possible future research within the area are proposed. / Under det senaste decenniet har teknik som underlättar hushållens elproduktion och lagring haft en hastig utveckling tillsammans med en betydande kostnadsminskning. Forskning pekar på en ökad andel hushållsproducerad el inom de befintliga nationella elnäten över hela världen. I vissa fall är självförsörjning möjligt där hushållen kan koppla bort sig från nätet och bli oberoende av sin elförsörjning, med andra ord gå off-grid. Vidare leder en potentiell förändring mot offgrid till ytterligare påtryckningar på hur elsystemet är uppbyggt, vilket utmanar många aktörers sätt att agera. Beroende på geografisk plats så varierar förutsättningarna för självförsörjning. Sverige är ett land med stora säsongsvariationer i och med sin nordliga position, vilket väcker frågan om off-grid hushåll är genomförbara i Sverige och hur de kan skulle kunna etableras. För att undersöka möjliga förändringar inom stora tekniska system som elsystemet, som är en viktig del av samhället, har teorier inom socio-tekniska system visat vara till stor nytta. Däremot saknar dessa teorier emellertid den mer tekno-ekonomiska aspekten av konkreta och framtida investeringskostnader ur ett konsumentperspektiv, vilket antyder ett befintligt forskningsgap. Följaktligen är syftet med den här studien att ge ytterligare inblick om off-grid-applikationer i svenska sammanhang. Vilket har gjorts genom att undersöka vilka omständigheter som kan leda till att befintliga elkonsumenter går off-grid. Forskningsprocessen och strukturen i rapporten kan vara svårtolkat, men studien har fokuserat på att kombinera teorier kring socio-tekniska förändringar samtidigt som man använder teknoekonomisk modellering för att stärka arbetet. Data samlades in i form av en litteraturstudie och intervjuer för att ge en holistisk representation av off-grid och dess koppling till elsystemet. Utöver litteraturstudie utfördes kompletterande modellering av hushållsanslutna, prosumeroch off-gridhushåll. Resultaten pekar mot scenarion där off-grid når nätparitet under de kommande två decennierna, vilket kommer att öka den ekonomiska rationaliteten för att investera i ett off-grid. Det finns det för närvarande inga ekonomiska skäl till att investera off-grid-applikationer med tanke på de relativt låga elkostnaderna i Sverige idag. Förhållandena visar dessutom löfte om att potentiella användare ser förbi ekonomin och har istället en stark vilja mot självständighet. Implikationer tyder emellertid på att det svenska elnätets höga tillförlitlighet och låga pris hindrar nya radikala innovationers förmåga att ta få fäste. Det är argumenterbart att den här studien har bidragit med att fylla forskningsgapet mellan socio-tekniska förändringar och tekno-ekonomiska projektioner inom elsystem. Samtidigt har studien bidragit till det vetenskapliga området kring socio-tekniska visat på möjligheten och fördelen i att kombinera teorier kring socio-teknisk förändring och tekno-ekonomiska förändringar. Dessutom kan det hävdas att resultaten av den här studie visar att konsumenten har en större roll i utvecklingen av applikationer utanför nätet än vad teorierna föreslår. Slutligen är elsystemet en komplex mekanism, och för att ytterligare stärka uppfattningen om hur en relativt ny applikation, som i fallet utanför nätet, kommer att påverka systemet föreslås lämpliga förslag för eventuell framtida forskning inom området.