Although the concept of tensegrity structures was invented in the beginning of the twentieth century, the applications of these structures are limited, partially due to their low stiffness. The stiffness of tensegrities comes from topology, configuration, pre-stress and initial axial element stiffnesses.  The first part of the present work is concerned with finding the magnitude of pre-stress. Its role in stiffness of tensegrity structures is to postpone the slackening of cables. A high pre-stress could result in instability of the structure due to buckling and yielding of compressive and tension elements, respectively. Tensegrity structures are subjected to various external loads such as self-weight, wind or snow loads which in turn could act in different directions and be of different magnitudes. Flexibility analysis is used to find the critical load combinations. The magnitude of pre-stress, in order to sustain large external loads, is obtained through flexibility figures, and flexibility ellipsoids are employed to ensure enough stiffness of the structure when disturbances are applied to a loaded structure.  It has been seen that the most flexible direction is very much sensitive to the pre-stress magnitude and neither analytical methods nor flexibility ellipsoids are able to find the most flexible directions. The flexibility figures from a non-linear analysis are here utilized to find the weak directions.  In the second part of the present work, a strategy is developed to compare tensegrity booms of triangular prism and Snelson types with a truss boom. It is found that tensegrity structures are less stiff than a truss boom when a transversal load is applied. An optimization approach is employed to find the placement of the actuators and their minimum length variations. The results show that the bending stiffness can be significantly improved, but still an active tensegrity boom is less stiff than a truss boom. Genetic algorithm shows high accuracy of searching non-structural space. / QC 20110524

Thin cylindrical shell structures may provide an interesting breakthrough for deployable  structures for small satellites. Its bi-stable behaviour allows two different stable configurations: coiled and deployed. Several projects worldwide are using tape springs for satellites and for the SEAM project, at KTH, 1 meter long tape springs will be used for booms. This thesis investigates the energy stored inside the tape spring according to its layup configuration and the different fiber orientations. With a thickness around 0.3 mm and a length of one meter, the booms will deploy sensors with a quite low deployment speed in order to minimize the shock load during the deployment phase. A Matlab code is written to compare the stored strain energy. Another aim is to find an adequate layup all along the tape spring, it means change the fiber orientation to decrease the energy released, but also generating main manufacturing issue.

Svenska bostadsmarknaden har de senaste åren varit ett hett diskussionsämne i media. Kanske beror det på att bostadspriserna har stigit i en snabbare takt de senaste 15 åren jämfört med de senaste 60 åren, vilket har skapat diskussioner kring en eventuell prisbubbla som skulle orsaka stora problem för många. När nobelpristagaren i ekonomi 2013 Robert Shiller samtidigt som det blev officiellt att han blivit tilldelad priset, gick ut med att han tror att risken för en bubbla är stor på Svenska bostadsmarknaden, var ingenting som fick debatten att upphöra. Efter uttalandet har bostadspriserna gått upp med ännu raskare takt än vad de gjort tidigare och gör frågan än mer aktuell än tidigare. Syftet med denna rapport är att undersöka vilka faktorer som är tillämpliga vid en prisbubblas bildande samt undersöka huruvida risken är stor idag för att en sådan ska inträffa med fokus på vad som vad som skedde under 90-talet när en prisbubbla senast uppstod på den Svenska bostadsmarknaden. Har vi idag en stor risk för en bostadsbubbla i Sverige? Samt vilka faktorer tyder på att risken är stor respektive vilka tyder på att risken är mindre? Det är några av frågorna som ska bli besvarade i uppsatsen För att kunna undersöka huruvida bubbla föreligger har personer med lång erfarenhet inom byggbranschen intervjuats som också har en relevant befattning inom respektive institution eller företag. Resultatet visar att många faktorer pekar på att det inte finns någon bubbla i Sverige, samtidigt som det fortfarande inte går att förkasta att risken finns, då vissa faktorer pekar på just det. Det som visar sig mest troligt är dock en mer jämn marknad där priserna varken går upp eller ner. / Swedish housing market in recent years has been a hot topic in the media. Perhaps it is because housing prices have risen at a faster pace over the past 15 years compared to the past 60 years, creating discussions about a possible price bubble that could cause major problems for many. When the Nobel Prize in economics in 2013, Robert Shiller, while it became official that he has been awarded the prize, went out with that he believes that the risk of a bubble is big at the Swedish housing market, this did not put an end of the debate. After the statement, housing prices have gone up even more rapidly than what it has previously and makes the issue even more relevant than before. The purpose of this report is to examine the factors that are relevant at a housing bubble formation and examine whether the risk is big today to such a thing to occur, with a focus on what happened in the 90s when a price bubble later arose on the Swedish housing market. Do we have a high risk of a housing bubble today on Swedish housing market? What factors suggest that the risk is big and which suggest that the risk is less? These are some question that will be answered during the essay In order to investigate whether a bubble exists or not, people with long experience in the construction industry were interviewed who also has a relevant position within the respective institution or company. The result shows that many factors indicate that there is no bubble on the Swedish housing market, while it still does not reject that possibility exists, certain factors indicate just that. It turns out that most likely, however, a more stable market where prices either go up or down.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / Identity is a concept that has received a multiplicity of very diverse approaches and references throughout the history of ideas. Cultural studies have approached with special interest the discussion around the contemporary meanings of this term. This study proposes the concept of gastronomic identity and examines its definition based on Stuart Hall's research on discursive identity. The explanatory capacities of this concept will become evident when it is applied to the case of Peruvian gastronomy through the analysis of texts located at the beginning of the so-called Peruvian gastronomic boom between 1980 and 1995. © 2022 Elsevier B.V.

The Utah State University Aerolab developed and tested a set of tools for rapid prediction of the loudness of a sonic boom generated by supersonic transport aircraft. This work supported a larger effort led by Texas A&M to investigate the use of adaptive aerostructures in lowering sonic boom loudness at off design conditions. Successful completion of this effort will improve the feasibility of supersonic commercial transport over land. Funding was provided by a NASA University Leadership Initiative grant to several universities, including Utah State University, as well as industry partners to complete this work over a five year period. The work presented in this thesis was done over the first year of the grant. The Aerolab team was specifically tasked with developing a set of tools for rapidly predicting the sonic boom loudness of supersonic aircraft. Specifically, this work included an assessment of the existing analysis tools available followed by the planning, development, and testing of a framework of tools for performing the needed calculations. Results of the framework were compared against high fidelity solutions available from the 2017 AIAA Sonic Boom Prediction Workshop. These comparisons revealed that panel methods perform well for simple geometries. However, localized errors appear when modeling more complex geometries that reduce the accuracy of the predicted sonic boom loudness. It was found that these localized errors were a consequence of the inherent assumptions built into panel methods. Consequently, in future work, it may be necessary to develop techniques for combining the results of panel methods with higher fidelity methods or to revisit the panel method formulation.

Fastighetsmarknaden är en ständigt föränderlig marknad, där priserna och efterfrågan på bostäder varierar beroende på låg- och högkonjunktur. Detta påverkar fastighetsmäklare genom att de ständigt behöver anpassa sina strategier utifrån omständigheterna. Syftet med denna studie är att presentera strategier som kan vara vägledande för en fastighetsmäklare. Vår studie baseras på en kvalitativ forskningsansats med empiri som baseras på semistrukturerade intervjuer med erfarna fastighetsmäklare som är verksamma i Skåne. Studien visar att det finns flera faktorer som påverkar en fastighetsmäklares strategi. Exempel på dessa faktorer är sociala mediers påverkan på förmedling, vikten av företagskultur, word- of- mouth och kundlojalitet. Studien betonar också vikten av fastighetsmäklares lyhördhet och kunskap inom fastighetsbranschen för att kunna ge kunderna korrekt rådgivning och vinna deras förtroende. Genom att använda dessa strategier kan en fastighetsmäklare bättre hantera de ständiga förändringarna på fastighetsmarknaden och utvecklas i sitt yrke. / The real estate market is an industry that is constantly changing, where prices and demand for housing are vary depending on the economic boom and recession. This affects real estate agents in a way that they constantly need to adapt their strategies based on the circumstances. The purpose of this research is to present strategies that can be a guide for a real estate agent. Our study is based on a qualitative research approach with empirical data based on six semi-structured interviews with experience brokers who are active in the real estate industry in Skåne. The study shows that there are several factors that can have an impact on a real estate agent’s strategy. Examples of these factors include the impact of social media on brokerage, the importance of corporate culture, word- of- mouth and customer loyalty. The study is also emphasizes the importance of real estate agents being responsive and knowledgeable in the real estate industry in order to provide clients with accurate advice and gain their trust. By using these strategies, a real estate agent can better manage the constant changes in the real estate market and develop in their profession.

The thermal design of small satellite missions is critical for ensuring the performance and longevity of onboard instruments. This thesis focuses on the thermal design of Foresail-2, a 6U CubeSat mission to Geostationary Transfer Orbit (GTO), specifically addressing the thermal challenges associated with the magnetometer located at the end of a long boom featured on the satellite. The objective of this research is to estimate the orbital loads, study its effects and develop an effective thermal control strategy to maintain the frame, boom and magnetometer temperature within an optimal operational range throughout the mission duration. A steady state thermal analysis is conducted to evaluate the effects of the GTO environment on the satellite structure under different operational scenarios and design conditions. To achieve the desired thermal control, several potential regulation strategies are investigated, including passive thermal coatings, insulation materials, and active cooling methods. Furthermore, thermal simulations are performed to predict the temperature profiles and gradients within the boom and magnetometer assembly, enabling the identification of potential hotspots or areas prone to thermal stress using ANSYS software package. These findings contribute to the implementation of thermal design modifications and the optimization of the configuration of the boom and magnetometer to enhance thermal performance. The results of this thesis contribute to the development of a robust thermal design for Foresail-2 mission satellite. Moreover, the methodologies and insights gained from this research can be extended to other CubeSat missions with similar thermal requirements and constraints.

Not too long ago, commercial supersonic aircraft flights were part of the air transportation system. In the 1970's we had the Russian-built Tupolev Tu-144 and the BAC/Aerospatiale Concorde, the latest being tin operation for 27 years. The work documented in this dissertation focused on the viability of bringing back supersonic aircraft as a transportation mode. Throughout three years, Virginia Tech and a team from NASA have been combining efforts to develop a model capable of predicting future air travel demand for supersonic vehicles. The model can predict future supersonic commercial services and allows aircraft designers from NASA to optimize aircraft performance and characteristics by maximizing the potential air travel demand. The final product of this study was the development of the Low-Boom Supersonic Aircraft Model (LBSAM). The development progress took three years to be completed, and during each year, a version of the model with the preliminary predictions was made available to NASA. Each of the three versions of the model predicts future supersonic commercial services. What differentiates each version is the data, method, and aircraft type/design implemented; the latest version of the model is more realistic and provides a higher number of functionalities. The first version of the model predicted the possible supersonic commercial service for three aircraft types: each with two variations. An 18-seat, 40-seat, and 60-seat low-boom and non-low-boom aircraft were analyzed. The second version of the model analyzed a 20-seat and 40-seat low-boom, non-low-boom aircraft with restrictions and non-low-boom aircraft without restrictions. The latest version of the model tries to estimate potential demand for a 43-seat and a 52-seat supersonic low-boom aircraft design. The low-boom concept refers to the implementation of technology that reduces the loudness of a sonic boom. A non-low-boom concept refers to an aircraft flying faster than Mach 1 with the technology's implementation that reduces the loudness of a sonic boom. The final results suggest that for a 52-seat LBSA, the potential worldwide demand is as follows. • 33.4 million seats worldwide. Assuming an overland range of 3,200 nm., an overland Mach 1.7, and an overland fuel scale factor of 0.98. • 772 aircraft needed worldwide. Assuming an overland range of 2,800 nm., an overland Mach 1.7, and an overland fuel scale factor of 0.90. • 1,032 one-way OD pairs where LBSA can operate. Assuming an overland range of 2,800 nm., an overland Mach 1.7, and an overland fuel scale factor of 0.90. The LBSAM is mainly driven by the cost per passenger mile values calculated for each one-way Origin-Destination (OD) pair. Additional uncertainties in the model include the market share and annual aircraft utilization. The market share refers to the percent of the demand that will switch from current subsonic commercial services to commercial supersonic services. During the three-year work, we considered a market share of 50% and 100%. Aircraft utilization refers to the number of hours that the airline will be able to use the aircraft. The majority of the projections were based on a 3,500-hour aircraft utilization. / Doctor of Philosophy / Not too long ago, commercial supersonic aircraft flights were part of the air transportation system. An aircraft flying faster than the speed of sound is known as an aircraft flying at supersonic speed. Current commercial aircraft fly at subsonic speed. Subsonic speed refers to aircraft flying at a speed lower than the speed of sound. In the 1970's we had the Russian-built Tupolev Tu-144 and the BAC/Aerospatiale Concorde, the latest being tin operation for 27 years. The work documented in this dissertation focused on the viability of bringing back supersonic aircraft as a transportation mode. Throughout three years, Virginia Tech and a team from NASA have been combining efforts to develop a model capable of predicting future air travel demand for supersonic vehicles. The model can predict future supersonic commercial services and allows aircraft designers from NASA to optimize aircraft performance and characteristics by maximizing the potential air travel demand. The purpose of this dissertation effort is to provide a better understanding of what could be the potential commercial demand for supersonic flight in the near future. We consider all the benefits and characteristics of supersonic flight and studied in detail what percentage of the travelers might be willing to migrate from the current subsonic market to the supersonic market. We estimated this ratio by studying the spending behavior of passengers in the current market. How much more are passengers willing to pay to save time? We can infer how much travelers value their time by comparing direct flights versus flights with an intermediate stop. The results show that a demand of 33.4 million seats could be reached by the year 2040. The supersonic market would consist of more than one thousand one-way origin-destination pairs worldwide, and more than seven hundred supersonic aircraft are expected to satisfy the forecast demand.

In this thesis, an output-only experimental modal testing and analysis technique known as the Natural Excitation Technique (NExT) is examined for use with large residential structures and interior cavities. The technique which assumes a random, stationary input causing the response data is reviewed and extended for the first time to include the assumption of an impulse input. This technique is examined with respect to the experimental modal analysis of single and two room residential structures. Each structure is first tested using conventional modal testing methods. Then, NExT is applied using each structure's response to a simulated sonic boom, an impulsive input. The results of these analyses along with the results obtained from a finite element model are compared. Then, the interior cavities enclosed by the residential structures are examined using NExT. Therefore, this thesis also demonstrates the successful use of NExT on acoustic systems for the first time. Three configurations of the interconnected cavities enclosed by the two room structure are considered to study physical phenomena. Both interior pressure response to random, stationary inputs and the sonic boom response are used with NExT to determine modal properties. The results of these analyses are compared to a theoretical analysis. Advantages to using NExT with both the response to a random, stationary input and an impulsive input are demonstrated for structural and acoustic systems. / Master of Science

Alors que les « baby-boomers » arrivent à la retraite, plusieurs prédictions indiquent qu'un nombre important d'entre eux déménagera dans un centre-ville, engendrant ainsi un embourgeoisement du centre-ville. Le but de ce mémoire est d'examiner les effets d'une arrivée massive de retraités sur la structure physique, économique et sociale d'une ville stylisée. À cette fin, nous adaptons un modèle d'appariement urbain développé par Wasmer et Zenou (2002) afin d'étudier les choix de lieu de résidence des travailleurs et des chercheurs d'emploi, mais en y ajoutant un groupe qui ne participe pas au marché de l'emploi : les retraités. Notre principal résultat est que, selon les valeurs de plusieurs paramètres exogènes (entre autres, le taux de chômage et les frais de transport), trois situations peuvent se produire sur les marchés de l'emploi et residentiel : soit il existe un équilibre général unique dans lequel les salaires, les loyers et le reserrement du marché du travail sont déterminés de façon endogène, soit il en existe deux, soit il n'en existe aucun. / As baby boomers retire, there have been predictions that a large number of them would move to city centres, thereby driving gentrification of downtowns. The purpose of this thesis is to investigate the effect of the arrival of a large number of retirees on the physical, economic and social structure of a stylised city. In order to do so, we adapt an urban job search model developed by Wasmer and Zenou (2002) to study the location choices of workers and job seekers by adding a group which does not participate in the labour market: retirees. Our main result is that, depending on various exogenous parameters (including the unemployment rate and transportation costs), one of three possibilities can occur on the labour and housing markets: a unique general equilibrium determining wages, rents and labour market tightness endogenously, multiple such equilibria or no equilibrium at all.