Recent years have seen a renewed interest in Variable Speed Limit (VSL) strategies. New opportunities for VSL as a freeway metering mechanism or a homogenization scheme to reduce speed differences and lane changing maneuvers are being explored. This paper examines both the macroscopic and microscopic effects of different speed limits on a traffic stream, especially when adopting low speed limits. To that end, data from a VSL experiment carried out on a freeway in Spain are used. Data include vehicle counts, speeds and occupancy per lane, as well as lane changing rates for three days, each with a different fixed speed limit (80 km/h, 60 km/h, and 40 km/h). Results reveal some of the mechanisms through which VSL affects traffic performance, specifically the flow and speed distribution across lanes, as well as the ensuing lane changing maneuvers. It is confirmed that the lower the speed limit, the higher the occupancy to achieve a given flow. This result has been observed even for relatively high flows and low speed limits. For instance, a stable flow of 1942 veh/h/lane has been measured with the 40 km/h speed limit in force. The corresponding occupancy was 33%, doubling the typical occupancy for this flow in the absence of speed limits. This means that VSL strategies aiming to restrict the mainline flow on a freeway by using low speed limits will need to be applied carefully, avoiding conditions as the ones presented here, where speed limits have a reduced ability to limit flows. On the other hand, VSL strategies trying to get the most from the increased vehicle storage capacity of freeways under low speed limits might be rather promising. Additionally, results show that lower speed limits increase the speed differences across lanes for moderate demands. This, in turn, also increases the lane changing rate. This means that VSL strategies aiming to homogenize traffic and reduce lane changing activity might not be successful when adopting such low speed limits. In contrast, lower speed limits widen the range of flows under uniform lane flow distributions, so that, even for moderate to low demands, the under-utilization of any lane is avoided. These findings are useful for the development of better traffic models that are able to emulate these effects. Moreover, they are crucial for the implementation and assessment of VSL strategies and other traffic control algorithms.

Tourism is one of the fastest-growing industries in the world and bears significant weight in global economic terms. However, there are concerns about the sustainability of the industry from an environmental and social/cultural perspective. One of the world’s top ten international tourism destinations, Thailand, had a record-breaking 39 million international tourists in 2019 but is expected to fall to around 14 million in 2020, the lowest level in 14 years, due to COVID-19. These impacts can be especially severe in small tropical islands where the land base is small, resources scarce, and local populations have low incomes and limited opportunities for livelihood diversification. Especially amid a global pandemic and the impending risks of climate change, it is crucial to reset, carefully consider concerns about sustainable tourism development, and move forward with management regimes that better embrace sustainability principles. This thesis examines the application of sustainable tourism using Koh Phangan, Koh Samui, and Koh Tao in the Gulf of Thailand as case studies to aid in sustainability planning for the future, particularly for island tourism destinations. Data were collected using a standardized questionnaire administered to 1261 tourists visiting the three islands during the peak tourism season (January to March) of 2018. The findings are presented within this thesis in three papers. The first paper focussed on the behavioral approach and compared visitors to each island, noting differences in tourist demographics, travel characteristics, motivation factors, and areas of management concern identified. The second paper focussed on the limits of acceptable change approach and used cluster analysis of visitor motivations to identify three types of visitors that were described in terms of the specialization concept: Cluster 1 (“very high importance generalists”), Cluster 2 (“high importance generalists”), and cluster 3 (“mixed importance”). While cluster 1 had the greatest mean importance scores for all environmental, social, economic, and logistical factors, it identified the most areas of concern whereas cluster 3 identified the least. The third paper explored scenario planning as a vehicle for sustainable tourism planning on the island of Koh Phangan and was framed within the Tourism Area Life Cycle (TALC), Tourism Opportunity Spectrum (TOS), and Ecotourism Opportunity Spectrum (ECOS) models. Most respondents preferred the “green scenario” in terms of accessibility, amount of visitors, development, food and accommodation, transportation around the island, traffic, waste management, water storage, and the scale of tourism. Collectively, these findings suggest that tourists can play an important role in identifying management priorities and that tourists tend to support a more sustainable tourism industry, as opposed to a focus on “mass tourism”, sometimes referred to as “sun, sea, sand” tourism. The study argues for adopting place-based planning practices and creating educational opportunities to ensure that the benefits of tourism are not outweighed by the costs. Especially as the tourism industry continues to expand, there is often a push to enhance visitation and the economic benefits that tourism provides; however, it is important to consider the environmental, social, economic, and logistical capacities of a tourism destination. / Graduate / 2021-08-21

Vid en ombyggnation av Henriksdals reningsverk har ett vertikalschakt utformats och anlagts. Under berguttaget tillämpades extensometermätningar för att följa upp deformationer i en bergpelare mot en befintlig tunnel. Mätningar utfördes automatiserat och regelbundet. För uppföljning av deformationer tillämpades tre larmnivåer avgränsade av två larmgränser vid 1.0 mm samt 3.0 mm deformation och var förbundna till olika motåtgärder. Målet med detta arbete harvarit att studera hur tillämpade larmgränser har presterat relativt dokumenterade och prognostiserade deformationer ur ett sannolikhetsbaserat perspektiv. Samt vid behov formulera och föreslå nya larmgränser. En litteraturstudie om modellering av bergmassor samt mekaniska egenskaper hos förekommande bergmassa av gnejs genomfördes. Därefter modellerades objektet för vidare numerisk analys genom FEM i Plaxis 3D. Med grund i uppställd modell kunde in-situ spänningsfältet skattas och modellen optimeras. En känslighetsanalys för bergmassans hållfasthetsparametrar utfördes och de fyra mest känsliga parametrarna: γ, ν, σci, Qbas, applicerades statistiskt i efterföljande studier. Föreslagna och tillämpade larmgränser studerades genom utförande av Monte Carlo-simuleringar. Använda deformationsbaserade larmgränser återfanns inte vara tillfredsställande och nya individuella töjningsbaserade gränsvärden framställdes. De ursprungliga deformationsbaserade larmgränserna resulterade för längre mätankare i utlösta larm och visades vara ouppnåeliga för kortare mätankare. En resulterande sannolikhet för överskridande av föreslagna varningsgränser vid dragtöjning skattades till storleksordningen 10−2 till 10−1 samt för stoppgränserna vid dragtöjning till 10−4. Sannolikheterna för överskridande av föreslagna larmgränser vid trycktöjning var inte möjliga att uppskatta för det studerade fallet. / During a rebuild of Henriksdal wastewater treatment plant, a vertical rock shaft was constructed. During the excavation, extensometers were used for monitoring deformations in a rock pillar against an existing tunnel. Measurements were automatically and regularly performed. Three alarm levels for follow up of the deformations were used and associated with different counter measures. The alarm levels were divided by two alarm limits at 1.0 mm and 3.0 mm deformation. The goal with this work was to study how the applied alarm limits from a probabilistic point of view have performed relative to obtained and forecasted deformations. And, if necessary, propose new alarm limits. A literature study about modeling of rock masses and mechanical properties of the occurring gneiss at site was performed. The object was thereafter modeled for further numerical analyzes using FEM in Plaxis 3D. Based on the performed model, the in-situ stress field could be estimated,and the model was further optimized. A sensitivity analysis of the rock mass strength parameters was conducted and the four most sensitive parameters: γ, ν, σci, Qbas, were applied as probabilistic in the following studies. Proposed and applied alarm limits were studied through Monte Carlo simulation. Applied deformation-based alarm limits were found not to be sufficient and two new strain-based were prescribed. The deformation-based limits were for the longer extensometer anchors resulting in triggered alarms and were only considered to be applicable for anchor lengths between 3.0 to 5.0 m. The probability of exceeding the proposed warning limits for tensile strain was estimated to be of a magnitude 10−2 to 10−1 and for the stop limits to be of a magnitude 10−4. The probabilities of exceeding the proposed alarm limits during compressive strain were not possible to estimate for the studied case.

[pt] Esta dissertação investiga o uso de discursos apofáticos como ferramentas epistemológicas nas situações em que a linguagem parece alcançar seus limites, com ênfase especial no contexto místico-religioso. Como falar de Deus, compreender a natureza última da realidade ou conceber o que havia “antes” da origem do universo? Tanto místicos, religiosos e poetas quanto filósofos, físicos e cosmólogos lidam com questões como essas há bastante tempo. Ao longo da história, a linguagem catafática (afirmativa) pareceu a muitos destes não dar conta de respondê-las; e, percebendo-a como insuficiente, as grandes religiões, em especial, adotaram um tipo de discurso que veio a ser conhecido como discurso apofático, ou via negativa. A fim de examinar algumas técnicas de negação empregadas por místicos e contemplativos diante das dificuldades que encontram para falar sobre o inefável, esta dissertação contrasta as obras de duas figuras centrais em suas respectivas tradições religiosas: Teologia Mística, do cristão Dionísio Areopagita, e Fundamentos do Caminho do meio, do budista Nagarjuna - textos conhecidos por levarem a negação ao extremo. Por meio dessa comparação, e apoiando-se, principalmente, nos comentadores Denys Turner, Eric Perl e Giuseppe Ferraro, este estudo aponta e discute diferenças significativas entre as linguagens negativas empregadas nas duas obras. Discute por fim, de modo pontual, como esses discursos se relacionam com contrapartes e paralelos contemporâneos, como o pensamento filosófico de Jacques Derrida e as descobertas da física moderna no início do século XX. / [en] This dissertation seeks to investigate the use of apophatic discourses as epistemological tools in situations where language seems to reach its limits, with special emphasis on the mystical-religious context. How to talk about God, understand the ultimate nature of reality or conceive what was before the origin of the universe? Mystics, religious people and poets, as well as philosophers, physicists and cosmologists have been dealing with issues like these for a long time. Throughout history, catapathic (affirmative) language has seemed, to many of them, to be unable to answer these questions; and, perceiving it as insufficient, the great religions, in particular, adopted a type of discourse that came to be known as apophatic discourse, or via negativa. In order to examine some techniques of negation employed by mystics and contemplatives in the face of the difficulties they encounter in talking about the ineffable, this dissertation contrasts the works of two central figures in their respective religious traditions: Mystical Theology, by the Christian Dionysius, the Areopagite, and The Fundamental Wisdom of the Middle Way, by the Buddhist Nagarjuna - texts known for taking denial to the extreme. Through this comparison, and relying mainly on the commentators Denys Turner, Eric Perl and Giuseppe Ferraro, this study points out and discusses significant differences between the negative languages used in the two works. Finally, it discusses, briefly, how these discourses relate to contemporary counterparts and parallels, such as the philosophical thought of Jacques Derrida and the discoveries of modern physics in the early 20th century.

Sulfide soils are silty soils, often found in saturated conditions, under the groundwater level. Characteristics of these soils, including particle size distribution and consistency limits along with chemical composition and environmental properties, cause excavation to be necessary for construction purposes. The excavated sulfide soil usually is transported and deposited in landfills. These soils are either deposited in saturated conditions or chemical buffers are added to the soil to prevent acidification. Special conditions of these landfills complicate the disposal procedure and the landfill maintenance which makes those financially expensive. Reusing sulfide soil in construction is a solution to reduce the expenses related to the management of sulfide soils. Since the mechanical properties of these soils are not suitable for construction purposes, the first step is to improve soil characteristics to the level that fulfills the needs of construction applications. One solution to improve the mechanical properties of the soil is adding a binder to the soil. The main focus of the research was to improve the mechanical properties of soil. The research activities were divided into two parts. The first part was conducted in a laboratory environment to develop mixtures, while the second focused on transferring the results to field conditions. The laboratory tests included mixing soil and binder i.e., cement was added to the soil at different percentages to evaluate the soil improvement. An unconfined compressive strength (UCS) test was conducted on the stabilized sample to evaluate the efficiency of the stabilization. The resultsof UCS for the stabilized samples were compared. Since the soil contains a high amount of water, the traditional sample preparation was not suitable. Therefore, an alternative method was developed and evaluated. Moreover, the effect of curing time on the strength and consistency limit of stabilized samples was evaluated. At last, the effect of different variables, including porosity, binder content and initial water content, on the UCS of soil was investigated to identify potential correlation between UCS and different soil variables. The results of the tests showed that adding a binder, regardless of the type of sulfide soil, positively affects the UCS of prepared samples and increasing the curing time increased the UCS of the samples. At higher cement content, the effect of curing time was more significant. Also, it was shown that at higher water content, the effect of binder is lower in comparison with the same soil at lower water content. By lowering the water content, the strength of stabilized soil reaches a maximum and drying further the soil, below the optimum water content, led to strength reduction. A correlation between UCS of sample and porosity/binder ratio was employed to predict the strength behavior of stabilized soil based on variables such as porosity, initial water content and binder dosage. In order to evaluate if laboratory results can be applied to geotechnical applications, the second part of this research included a field mixing experiment for a large-scale mixture of soil and cement. The effect of the mixing procedure with common equipment on the homogeneity of industrial-size mixture was investigated. A sampling strategy for collecting representative samples of mixture was selected and assessed. the number of mixing steps and the effect of binder dosage on the uniformity of samples were studied. Results of UCS of samples prepared from field and laboratory mixture were compared and evaluated. A field evaluation was conducted to determine the quality of the mixture and how many mixing steps are required to reduce variability between samples. Two different percentages of binder were added to the 5 Tons of soil. The UCS test samples were prepared from the soil-cement mixture in the same way as they were prepared in the laboratory and cured for a specific time. The UCS test was conducted on cured samples. The test results were compared to evaluate the mixture homogeneity in the field. The results showed that homogeneous mixtures can be obtained in the field with the available equipment. Assessing the sampling strategy showed that increasing the sampling sections from 5 to 12 and preparing single UCS sample from the collected soil provides representative samples from the soil mixture pile. Additionally, it was shown that by increasing mixing steps from 2 to 3, it was possible to eliminate samples with notable lower strength than average UCS. A greater number of mixing steps improves homogeneity while reducing the average UCS. It was found that mixing soil and binder in the laboratory improves strength better than mixing them in the field. When applying laboratory results to field design, this point must be taken into account.

The dire state of Cuban internet connectivity has inspired local informal innovations. One such innovation is El Paquete, a weekly distribution of downloaded content spread through an informal network. Taking a postcolonial approach, I investigate through user experiences how this network operates in a resource-poor environment. This investigation articulates a model of El Paquete centered on social interactions, which inform the system’s function but also shape El Paquete’s design and role in society. Based on this model, a set of speculative design exercises probe possibilities to streamline El Paquete’s compilation, involve consumer preferences in its design directions, or act as a disruption tolerant network. In uncovering the technical possibilities of El Paquete, these designs illuminate how its current design serves Cuban communities by embodying realities and limitations of Cuban society. El Paquete’s embodiment of informal innovation serves as a call to designers to continuously rethink development design processes, centering communities and their knowledge and technical practices. / Det kritiska tillståndet för den kubanska internetanslutningen har inspirerat flertalet informella lokala innovationer. Ett exempel på en sådan innovation är El Paquete, vars lösning går ut på distribution av nedladdat innehåll som sprids veckovis genom ett informellt nätverk. Jag har undersökt hur detta nätverk fungerar i en resursfattig miljö genom att undersöka användarupplevelser ur ett postkolonialt perspektiv. I denna undersökning framförs en modell av El Paquete som inriktas på sociala interaktioner, vilket utgör systemets funktioner men som också formar El Paquete’s design och samhällsroll. Baserat på denna modell undersöks möjligheterna till att effektivisera El Paquete’s sammanställning, genom ett antal olika spekulativa designövningar som inkluderar konsumentpreferenser i designinriktning, eller som ett avbrottstolerant nätverk. Dessa designer belyser hur dagens tekniska möjligheter med El Paquete är till nytta för kubanska samhällen genom förkroppsligandet av deras verklighet och begränsningar. El Paquete’s förkroppsligande av informell innovation fungerar som en uppmaning till designers att kontinuerligt ompröva utvecklingen av designprocesser som fokuserar på samhällets kunskap och tekniska praxis.

This research evaluates Intelligent Transportation System (ITS) implementation strategies to improve the safety of a freeway once a potential of a crash is detected. Among these strategies are Variable Speed Limit (VSL) and ramp metering. VSL are ITS devices that are commonly used to calm traffic in an attempt to relieve congestion and enhance throughput. With proper use, VSL can be more cost effective than adding more lanes. In addition to maximizing the capacity of a roadway, a different aspect of VSL can be realized by the potential of improving traffic safety. Through the use of multiple microscopic traffic simulations, best practices can be determined, and a final recommendation can be made. Ramp metering is a method to control the amount of traffic flow entering from on-ramps to achieve a better efficiency of the freeway. It can also have a potential benefit in improving the safety of the freeway. This thesis pursues the goal of a best-case implementation of VSL. Two loading scenarios, a fully loaded case (90% of ramp maximums) and an off-peak loading case (60% of ramp maximums), at multiple stations with multiple implementation methods are strategically attempted until a best-case implementation is found. The final recommendation for the off-peak loading is a 15 mph speed reduction for 2 miles upstream and a 15 mph increase in speed for the 2 miles downstream of the detector that shows a high crash potential. The speed change is to be implemented in 5 mph increments every 10 minutes. The recommended case is found to reduce relative crash potential from .065 to -.292, as measured by a high-speed crash prediction algorithm (Abdel-Aty et al. 2005). A possibility of crash migration to downstream and upstream locations was observed, however, the safety and efficiency benefits far outweigh the crash migration potential. No final recommendation is made for the use of VSL in the fully loaded case (low-speed case); however, ramp metering indicated a promising potential for safety improvement.

Der erste Teil dieser Arbeit konzentriert sich auf die systematische Synthese von Informationen über Anpassung, Anpassungsstrategien, Einschränkungen und Grenzen auf globaler Ebene durch die Aufarbeitung der wissenschaftlichen Literatur und mit Hilfe von Techniken des maschinellen Lernens. In einem zweiten Schritt werden mittels einer Online-Umfrage und halbstrukturierter Interviews die Wahrnehmungen von Einschränkungen der Anpassungsmöglichkeiten in den kleinen Inselstaaten der Karibik bewertet, wobei der Schwerpunkt auf den Wechselwirkungen zwischen verschiedenen Arten von Einschränkungen und dem erheblichen Einfluss der fehlenden Anpassungsfinanzierung liegt. Schließlich wird ein zukunftsorientierter Ansatz verfolgt, bei dem Bottom-up- und Top-down-Daten kombiniert werden, um zu veranschaulichen, wie sich sozioökonomische Dimensionen im Zusammenhang mit Einschränkungen bis zum Jahr 2100 unter verschiedenen Szenarien der künftigen sozialen und wirtschaftlichen Entwicklungen entfalten könnten. Die Ergebnisse zeigen, dass die Anpassung derzeit schrittweise und weitgehend fragmentiert erfolgt. Die Erkenntnisse über die Anpassungspolitik nehmen rasch zu, aber es bestehen weiterhin geografische Ungleichheiten. Finanzen und Regierungsführung sind weltweit die größten Einschränkungen, wobei die kleinen Inselstaaten sowie Mittel- und Südamerika die meisten Einschränkungen und Grenzen melden. Die Wechselwirkungen zwischen den Einschränkungen können zu Grenzen und zusätzlichen Verlusten und Schäden führen. Dies unterstreicht die Notwendigkeit, die Einschränkungen parallel anzugehen und eine nachhaltige und gezielte Anpassungsfinanzierung zu gewährleisten. Mögliche Szenarien für die künftige Entwicklung zeigen, dass selbst in den optimistischsten Szenarien sozioökonomische Schlüsseldimensionen wie schwache Regierungsführung die Anpassung bis weit in die zweite Hälfte des 21. Jahrhunderts hinein erschweren werden. / The first part of this thesis focuses on systematically synthesising information on adaptation, adaptation policies, constraints and limits on the global level by reviewing scientific literature and with the support of machine learning techniques. Secondly, through an online-survey and semi-structured interviews, perceptions of constraints in Caribbean Small Island Developing States are assessed, by focusing on the interactions between different types of constraints and the significant influence of the lack of adaptation finance. Finally, a forward-looking approach combining bottom-up and top-down data is taken to illustrate how socio-economic dimensions related to constraints could evolve by 2100, under various scenarios of future development. The results show that adaptation is currently incremental and largely fragmented. Evidence on adaptation policy is rapidly growing but geographic inequalities persist. There is negligible data on adaptation reducing climate change risks. Finance and governance are found to be the most prominent constraints globally, with Small Island Developing States and Central and South America reporting most constraints and limits. Indeed, Caribbean Small Island Developing States face large financial constraints which in turn closely interact with governance, human capacity and information constraints and result in vicious circles. Interactions between constraints can lead to limits and additional losses and damages. This highlights the need to address constraints in parallel and for sustained and dedicated adaptation finance. Potential scenarios of future development show that, even under the most optimistic scenarios, key socio-economic dimensions such as weak governance will challenge adaptation well into the second half of the 21st century. The persistence of constraints, in particular in the most vulnerable regions, calls for stringent mitigation, improved adaptation and increased efforts to address losses and damages.

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