In recent years, bridge foundations have been in the spotlight throughout the nation. Bridges built over running water are susceptible to erosion or scour around their foundations. The reduction in load capacity to piers and abutments pose a safety risk to highway motorists. It has become necessary for engineers to examine and monitor these "scour critical" bridges. The difficulty arises with subsurface foundations of which very little is known about their construction. Hence, the methods applied to analyzing "Unknown Foundations" have become a necessary topic of research. This thesis explores a method to determine foundation lengths. Similar to Sonic Echo / Impulse Response, this procedure measures reflected shock waves sent through concrete pilings. The technique is non-destructive in nature and is performed near the surface of the foundation. The test is performed on the side of the exposed piling. Current methods are limited by the fact that the tops of most pilings are inaccessible due to pilecaps or beams. Often times, pilings are embedded in stiff soils, which have a dampening effect on the stress waves. This thesis employs a method of analysis that will overcome such limitations and provide engineers with another tool to determine subsurface foundation lengths.

Entangled polymeric fluids subjected to shear display a stress plateau through a range of shear rates. The formation of this plateau is often attributed to an entanglement-disentanglement transition in scientific literature. However, to our best knowledge in situ studies recovering the intermediate scattering function of polymer dynamics under shear have until now never been performed. This thesis documents the successful development of a high viscosity shear device whose interaction with polarized neutrons is small enough to allow use for Neutron Spin Echo spectroscopy. Further, first measurements towards the direct observation of the variation of the degree of entanglement throughout increasing shear are documented, albeit yet for too short Fourier times to measure beyond Rouse dynamics.

This study analyzes visual artifacts from three case studies, Hetch Hetchy Valley, Echo Park, and Glen Canyon, in order to contribute to scholarship devoted to environmental visual rhetoric. Through these studies, I address connections between aesthetics and environmental ethics and challenge scholarship that argues mainstream preservationist perspectives have adhered to an anthropocentric ideological paradigm. Grounding my argument in philosopher Arnold Berleant's notion of participatory aesthetics and deploying social semiotics and media analysis methodologies, I propose that two particular aesthetic grammars have been at use in mainstream environmental rhetorics, that which I call the wilderness sublime and the wilderness interactive. Present in the late 19th and early 20th centuries, and well documented in existing scholarship, the aesthetic of the wilderness sublime has operated through strict dichotomies between nature and culture that promote reductive views of human relationships with nature. Conversely, I argue that the aesthetic of the wilderness interactive, discoverable in artifacts from the mid-20th century to today, has worked to resist these dichotomies through the use of participatory elements that feature humans and nature in what Berleant calls a "relationship of mutual influence," falling within a more ecocentric ideological view. Through my analysis, I extend Berleant's theoretical application from photography to websites to argue that web-based rhetorics contain distinct potential for the realization of participatory features. In particular, I focus on the aesthetic, technological, social, archival, subjective, and epistemological dimensions proposed by Melinda Turnley to discuss dialogic features of websites that can work to engage diverse stakeholders. Through my findings, I offer a visual analysis heuristic that can be used to discover participatory aesthetics within visual artifacts and resist dualistic views of the environment. Likewise, I present a user analysis heuristic that can help identify targeted stakeholders and recognize participatory aesthetics within websites. Ultimately, this study answers the call of environmental aesthetics to address the realization of perceptual norms that offer more ethical conceptions of human relationships with nature, and it extends this focus into the digital environment to discuss the ability of web design and aesthetics to promote generative stakeholder dialogue in environmental protection and restoration.

This study investigated the critical behaviour of ternary mixtures of DOPC and DPPC, with cholesterol. The properties of model membranes such as these are studied in order to provide insight into aspects of complex biological systems. Experiments were performed using the Jeener echo, a static solid-state NMR technique, however no information about the critical phenomena was obtained. Conversely, the sideband linewidths measured from 2H MAS NMR are sensitive to temperature and dependent upon the phase behaviour. By fitting the linewidth data to an equation from Suwelack et al. (J. Chem. Phys., 1980; 73(6):2559-2569), the critical temperature and the critical exponent for the correlation length of the system were calculated. The critical exponent values obtained from these samples ranged between νc = 0.65 and νc = 1.2, which encompasses the critical exponents for both the 2D and 3D Ising models within error. The universality class for these model membranes cannot be unambiguously assigned yet.

No description available.

This thesis studies the design and implementation of an ultra-sonic water depth sounder. The depth sounder is implemented in a hand-held smart console used by divers. Since the idea of echo sounding is to measure the flight time between transmitting the signal and receiving the echo, the main challenge of this task is to find a time-of-flight (ToF) estimation for a signal in noise. It should be suitable for this specific application and robust when implemented in the device. The thesis contains an investigation of suitable ToF methods. More detailed evaluations of the matched filter, also known as the correlation method, and the linear phase approach are done. Aspects like pulse frequency and duration, speed of sound in water and underwater noise are taken into account. The ToF-methods are evaluated through simulation and experiments. The matched filter approach is found suitable based on these simulations and tests with signals recorded by the console. This verification leads to the implementation of the algorithm on the device. The algorithm is tested in real time, the results are evaluated and improvements suggested. / Denna rapport behandlar skattning av vattendjup med hjälp av ultraljudspulser och implementation av detta. Djupmätaren implementeras i en handhållen dykarkonsoll. Eftersom grundidén i ekolodning är att mäta tiden mellan att pulsen skickas iväg och att ekot tas emot är en stor del av utmaningen att hitta en lämplig metod för att skatta flykttiden för en signal i brus. Metoden ska passa för detta användingsområde och vara robust. Rapporten tar upp tidigare forskning gjord inom flykttidsestimering. De metoder som utvärderas för implementation är det matchade filtret, också kallad korrelationsmetoden, och linjär fas-metoden. Andra aspekter som avvägs och utreds är pulsfrekvens och pulsvaraktighet, ljudets hastighet och brus under vattnet. Metoderna för att skatta flykttid utvärderas genom simuleringar. Det matchade filtret bedöms vara lämpligt baserat på dessa simuleringar och experiment med data inspelad med konsollen. Denna verifikation leder till att algoritmen implementeras på konsollen. Den implementerade algoritmen testas i realtid, resultaten utvärderas och förbättringar föreslås.

Magnetic Resonance Elastography is a method of imaging the elasticity of soft tissues through measurement of small motions induced into a sample. It shows great promise in the detection of a wide variety of pathologies, especially tumours. An imaging protocol was developed to acquire MR elastography data for use in a clinical setting. A 3D gradient echo sequence was modified to allow for the detection of harmonic motion and tested on silicone phantoms and ex-vivo muscle and brain samples. The time for acquiring a high resolution, quantitative dataset of 3D motions was about 45 minutes. Our imaging method included motion encoding along all three coordinate axes and at several time points along the motion cycle. This time could be easily be reduced by more than half for future clinical use, while still retaining full quantitative data. A modified EPI sequence shows promise for even faster acquisition. The ability to detect the mechanical anisotropy of brain and muscle tissue in ex-vivo samples was also investigated. Initial results from the muscle data indicate a change in shear wavelength is observed for actuation along orthogonal axes. This is a strong indicator of anisotropy detection. Further work needs to be done to improve results from the brain sample as preliminary results are inconclusive.

In December 2009 Google had a press release, in which they stated that they would start individualize their users' search results. This is the year individualization began, according to Eli Pariser, who also coined the expression filter bubble. A filter bubble is said to occur when a user only receives individualized feeds, causing them to only consume information that align with their beliefs and excluding them from contradicting information. The main goal of this thesis is to evaluate the existence of filter bubbles and the effects of them. In order to reach the goal, an experiment on a large social media platform is conducted, as well as a qualitative literature study. The experiment consists of fourteen bots that are assigned different behaviors which are performed on a social media platform, which expresses that they use individualization of users' information feeds. The presented results from the experiment are based on data crawled from the bots' feeds. The main finding of the experiment is that no significant filter bubbles are observed and that users experience less exclusion the more of the feed they consume. The literature study consists of 24 papers that both do and do not support the theory of filter bubbles. The main effects found are that filter bubbles fosters polarization of opinions and confirmation bias. It is also said that this could lead to undermining deliberative democracy. / År 2009 talade Google om att de skulle börja anpassa sina sökresultat beroende på vem som använde deras tjänst. Detta lyftes fram av Eli Pariser år 2011, som då myntade uttrycket filterbubbla. Pariser menar att en person befinner sig i en filterbubbla om personen endast konsumerar innehåll som är anpassat efter tidigare visade intressen och därmed blir utesluten från information som utmanar personens åsikter och övertygelser. Det är omdiskuterat huruvida filter bubblor existerar eller inte och vilka effekter som kommer av att en person befinner sig i en. Detta arbete utförs med syfte att utvärdera filter bubblors existens och effekter på både individen och samhället i stort. För att uppfylla syftet genomförs ett experiment och en kvalitativ litteraturstudie. Experimentet består av fjorton nya medlemskonton på en stor social medieplattform där en automatisk mjukvara gillar specifika inlägg under sex veckors tid. Plattformen har uttryckligen framfört att de anpassar användarens flöde av inlägg efter dess beteende. Detta flöde sparas ner för samtliga fjorton konton, två gånger dagligen under sju veckors tid (en vecka extra efter att gillandet av inlägg slutat) och analyseras sedan i jakt på filterbubblor. Genom experimentet att skapa filterbubblor på en social medieplattform hittas inga bevis på att filterbubblor existerar på precis den plattformen. Den kvalitativa litteraturstudien innebär en ingående granskning av vetenskapliga artiklar och avhandlingar inom området. I de 24 arbeten som utvärderas är det åtta stycken som anser att filterbubblor existerar. Flera effekter av filterbubblor hittas i litteraturen och en av de negativa effekterna filterbubblor kan ha på individen är att förstärka behovet att bekräfta sina fördomar. Samhället kan också drabbas av effekter från filterbubblor, såsom försvagande av deliberativ demokrati. Deliberativ demokrati, även kallat samtalsdemokrati lyfter vikten av kommunikation för att utveckla och förstärka en demokrati.

Este trabalho tem dois propósitos principais. O primeiro compreende o estudo de um equipamento transceptor para viabilizar a transmissão digital de dados duplex a dois fins na malha telefônica comercial instalada. Um estudo inicial da linha de assinante e dos principais métodos de transmissão duplex e realizado. O método de cancelamento de eco e sugerido por conferir ao transceptor melhor desempenho. O transceptor tem a sua estrutura abordada e definida. Além do cancelador, todos os demais circuitos, julgados pelo autor como importantes, são analisados. Dentre os principais estão o codificador 2B1Q, os equalizadores adaptativos e a referencia adaptativa. O segundo propósito compreende o estudo de uma arquitetura capaz de implementar o cancelador do transceptor e sua especificação e simulação. Inicialmente, junto a proposta do equipamento, tipos de canceladores, formas de cancelamento e demais características relacionadas são abordadas. O algoritmo utilizado para a adaptação dos coeficientes e exposto, e, através de simulações, validado. Os problemas decorrentes do use de palavra finita em sistemas digitais sac. considerados. Os procedimentos da operação de cancelamento são especificados e as tarefas distribuídas. Após, finalizando este trabalho, propõe-se a parte operativa, composta por dois processadores, por um banco de registradores e por uma interface de entrada e saída. A arquitetura e descrita em linguagem HDC de descrição de hardware e apos simulada funcionalmente para validação das funções pretendidas. A parte de controle, parcialmente descrita também em HDC, tem algumas características comentadas . / This work has two main goals. The first one is the study of a transceiver equipment to allow two-wire duplex data digital transmission over the existing telephonic network. An initial study of the subscriber line and of the main duplex transmission methods is done. The echo cancellation method is suggested since higher performance transceiver may be obtained. The structure of the transceiver is considered and defined. Besides the echo canceller, all the others circuits deemed important by the author are analysed. The second goal comprehends the study of an architecture capable of implementing the transceiver echo canceller, and its specification and simulation. Initially, gearing to the equipment proposal, the type of cancellers, ways of cancelling and other related characteristics are approached. The algorithm used for the adaptation of coefficients is exposed and validated through simulations. The problems due to the use of finite word length in digital systems are considered. The cancelling operation procedures are specified and the different tasks are distributed. Finally, at the end of this work, the data path, composed of two processors, of a register bank and of an I/O interface, is proposed. The architecture is described in the HDC hardware description language, and later it is simulated for validation of the proposed functions. The control path, partially described in HDC also, has some of its characteristics addressed.

Este trabalho tem dois propósitos principais. O primeiro compreende o estudo de um equipamento transceptor para viabilizar a transmissão digital de dados duplex a dois fins na malha telefônica comercial instalada. Um estudo inicial da linha de assinante e dos principais métodos de transmissão duplex e realizado. O método de cancelamento de eco e sugerido por conferir ao transceptor melhor desempenho. O transceptor tem a sua estrutura abordada e definida. Além do cancelador, todos os demais circuitos, julgados pelo autor como importantes, são analisados. Dentre os principais estão o codificador 2B1Q, os equalizadores adaptativos e a referencia adaptativa. O segundo propósito compreende o estudo de uma arquitetura capaz de implementar o cancelador do transceptor e sua especificação e simulação. Inicialmente, junto a proposta do equipamento, tipos de canceladores, formas de cancelamento e demais características relacionadas são abordadas. O algoritmo utilizado para a adaptação dos coeficientes e exposto, e, através de simulações, validado. Os problemas decorrentes do use de palavra finita em sistemas digitais sac. considerados. Os procedimentos da operação de cancelamento são especificados e as tarefas distribuídas. Após, finalizando este trabalho, propõe-se a parte operativa, composta por dois processadores, por um banco de registradores e por uma interface de entrada e saída. A arquitetura e descrita em linguagem HDC de descrição de hardware e apos simulada funcionalmente para validação das funções pretendidas. A parte de controle, parcialmente descrita também em HDC, tem algumas características comentadas . / This work has two main goals. The first one is the study of a transceiver equipment to allow two-wire duplex data digital transmission over the existing telephonic network. An initial study of the subscriber line and of the main duplex transmission methods is done. The echo cancellation method is suggested since higher performance transceiver may be obtained. The structure of the transceiver is considered and defined. Besides the echo canceller, all the others circuits deemed important by the author are analysed. The second goal comprehends the study of an architecture capable of implementing the transceiver echo canceller, and its specification and simulation. Initially, gearing to the equipment proposal, the type of cancellers, ways of cancelling and other related characteristics are approached. The algorithm used for the adaptation of coefficients is exposed and validated through simulations. The problems due to the use of finite word length in digital systems are considered. The cancelling operation procedures are specified and the different tasks are distributed. Finally, at the end of this work, the data path, composed of two processors, of a register bank and of an I/O interface, is proposed. The architecture is described in the HDC hardware description language, and later it is simulated for validation of the proposed functions. The control path, partially described in HDC also, has some of its characteristics addressed.