Esse trabalho descreve uma investigação prática e teórica de características aerodinâmicas de um modelo referente a um avião bimotor leve \"Piper PA-34 SENECA III\" construído em escala 1:6,5. Basicamente, duas configurações fazem parte da avaliação: \"asa limpa\" e Nacele \"Pusher\". O principal objetivo é o de avaliar o comportamento aerodinâmico da configuração \"Pusher\" em três diferentes posições através da obtenção de dados práticos e teóricos de distribuição de pressão estática no aerofólio e no próprio nacele na condição não motorizada. A metodologia emprega testes em túnel de vento de baixa velocidade para a aquisição dos dados experimentais através da variação do ângulo de ataque para as configurações citadas. A obtenção dos dados numéricos, como comparativos aos experimentais, é através da utilização do método dos painéis aplicado à aerodinâmica. Os resultados experimentais e teóricos mostram que a presença do nacele nas posições \"Pusher\" avaliadas gera interferência diminuindo à sustentação do aerofólio. / This work describes a practical and theoretical investigation of aerodynamic characteristics of a 1:6,5 scale model of a light twin-engined Piper Seneca III aircraft. Basically, two configurations are considered in this evaluation: clean wing and pusher nacelle. The principal objective is to evaluate the aerodynamic characteristics of the pusher configuration in three different positions, in order to obtain practical and theoretical data with reference to static pressure distribution on the surface of the aerofoil and of the nacelle in a power-off condition. The methodology employed used low speed wind tunnel test for the acquisition of experimental data for a selection of angles of attach, as cited. The generation of numerical data, to be compared the experimental equivalent, is though the use of a low order panel method. The experimental and theoretical results show that the presence of pusher nacelle in the positions mentioned generated interference, reducing the local lift of the aerofoil.

Esse trabalho descreve uma investigação prática e teórica de características aerodinâmicas de um modelo referente a um avião bimotor leve \"Piper PA-34 SENECA III\" construído em escala 1:6,5. Basicamente, duas configurações fazem parte da avaliação: \"asa limpa\" e Nacele \"Pusher\". O principal objetivo é o de avaliar o comportamento aerodinâmico da configuração \"Pusher\" em três diferentes posições através da obtenção de dados práticos e teóricos de distribuição de pressão estática no aerofólio e no próprio nacele na condição não motorizada. A metodologia emprega testes em túnel de vento de baixa velocidade para a aquisição dos dados experimentais através da variação do ângulo de ataque para as configurações citadas. A obtenção dos dados numéricos, como comparativos aos experimentais, é através da utilização do método dos painéis aplicado à aerodinâmica. Os resultados experimentais e teóricos mostram que a presença do nacele nas posições \"Pusher\" avaliadas gera interferência diminuindo à sustentação do aerofólio. / This work describes a practical and theoretical investigation of aerodynamic characteristics of a 1:6,5 scale model of a light twin-engined Piper Seneca III aircraft. Basically, two configurations are considered in this evaluation: clean wing and pusher nacelle. The principal objective is to evaluate the aerodynamic characteristics of the pusher configuration in three different positions, in order to obtain practical and theoretical data with reference to static pressure distribution on the surface of the aerofoil and of the nacelle in a power-off condition. The methodology employed used low speed wind tunnel test for the acquisition of experimental data for a selection of angles of attach, as cited. The generation of numerical data, to be compared the experimental equivalent, is though the use of a low order panel method. The experimental and theoretical results show that the presence of pusher nacelle in the positions mentioned generated interference, reducing the local lift of the aerofoil.

TITLE Efficacy of physiotherapeutic interventions in stroke patients with pusher and neglect syndrome. OBJECTIVES The aim of the thesis is to summarise current literature concerning two peculiar phenomena following stroke - pusher syndrome and neglect. Furthermore the work focuses on evaluation of efficacy of physiotherapeutic interventions. METHODS The thesis represents a critical review of a literature and it consists of three parts. The first one summarize issues concerning the pusher syndrome and neglect in general. In a special part you can find a detailed description of physiotherapeutic methods that are widely used in a rehabilitation treatment of these two neuronal symptoms. This work is concluded by evaluating results of effects of the therapeutic interventions that are discussed with respect to the future research. RESULTS Up till now there are no clinical trials concerning efficiacy of physiotherapeutic methods in a treatment of a pusher syndrome. The similar situation seems to be in case of a neglect syndrome as number of available clinical trials testing the efficiacy of physiotherapeutic techniques is very limited. The studies show positive results of a training of visual and spatial orientation or prism adaptation to effectively treat neglect patients. On the contrary, pharmacological...

Swimming is a fundamental feature in many living systems. Biological microorganisms move in the search of food, appropriate pH, temperature, mate and for many other elements crucial for life. A classic example is sperm cell, which travels thousands of its body length in the complex genital tract of females to reach the egg. Inspired by such unique character and diversified motion abilities of the biological world, researchers have always been intrigued to create small artificial microbots which could swim and perform complex tasks. In his famous talk ’There is plenty of room at the bottom’ in 1960, Richard Feynman suggested designing swallowable doctors which could travel in the blood vessels and perform the surgery. Although seemingly exquisite and far-fetched, this idea laid the foundation stone to pave the path towards building autonomously propelled artificial machines with applications ranging from targeted drug delivery to environmental remediation. However, considerable challenges are yet to be addressed before developing fully functional artificial machines, especially in the biomedical applications. For instance, directed transport in vivo, using man-made artificial machines face many obstacles starting from their fabrication, fuels for powering them and their interactions with the surroundings. Rapid changes in the environment in vivo, would make it difficult in selecting the ideal material and shape design of the microswimmer and would most probably require a flexible structure which could potentially squeeze itself and easily pass through small cavities. With most of the swimmers, in the past, being designed from inorganic materials, leave them unsuitable for biological applications. In addition, the environments inside an animal body is dominated by various complexity such as flows of bodily fluids, cavities and soft tissues. In laboratory settings, often these peculiarities are ignored as mostly the motion behavior is tested in stagnant conditions on solid substrates and it is unclear how would an artificial machine will behave in such complex environments. In this thesis, we combined the advances in microfluidics to benefit the microswimmer research manifold. In the last few years, microfluidics and micromotors have been used together in various instances because of their co-sharing regime of low Reynolds number and excellent fluid manipulation abilities at the microscale. In addition, microfluidics offer unique opportunities in designing structures with well-engineered shapes. With these points in mind, in this thesis, we used microfluidics to fabricate microswimmers and design custom made environments to mimic the complexity present in vivo, and to study the feedback of artificial swimmers in them. Specifically, in the first part of the thesis, two microfluidic strategies namely droplet microfluidics and stop-flow lithography were investigated to design hydrogel-based micromotors. Besides, in the next part, we developed complex environments and studied the motion behavior of conventional microswimmers in them. In the first subpart of the thesis, using droplet microfluidics, we designed polyacrylamide and poly (ethylene glycol) diacrylate (PEGDA) based Janus droplets using co-flowing phases with enzyme immobilized in one of the phases to confer asymmetry. The droplets were polymerized on-chip using UV polymerization. We found that the polyacrylamide and PEGDA 565 particles did not result into efficient bubble production when suspended in H2O2 solution and we explain this behaviour using the analogy of smaller pore size and possible poisoning of the enzyme by acrylamide. But, when a 10 v/v% PEGDA 700 was selected as the polymer material, it resulted in very efficient bubble evolution, although the Janus geometry was compromised which restricted swimming for these particles. The second subpart dealt with applying stop-flow lithography technique for designing hydrogel micromotors with different shapes and these shapes corresponded to different swimming modes. Exploiting laminar flow in the low Reynolds number region in the microfluidics channels, we fabricated micromotors with variable composition, shape and controlled active regions. Furthermore, we studied the different trajectories resulting from the complex interactions between swimmer body and fluid dynamics around it and connected them to the theoretical findings. We found close agreement between the experimental results and the theoretical outcomes: I-shaped structure behaved as a pump, U-shaped as a propeller and S-shaped as a rotor. Post fabrication, during real applications, the micromotors will be exposed to complex environments for instance interfaces and flows. To evaluate the feedback of microswimmers in these situations, in the next two sections, we designed custom made environments using microfluidics and we studied the response of well-studied Janus microswimmers in them. It should be noted that in the following two sections we used Janus particles rather than the bubble driven swimmers (fabricated in the first section) for simplicity. In this section, we designed an oil-water interface using a special microfluidic trap design and explored the motion behaviour of a very well-studied Pt@SiO2 Janus micromotors on them. The chip geometry facilitated on-demand merging of a droplet of particles and the ‘fuel’ (H2O2) inside the trap. Additionally, the large surface of the trap resulted in high surface energy which was compensated by partial wetting of the glass substrate. This partial wetting created patches of oil on the glass which we refer to as ‘oil dimples’. The dimples gave us the unique opportunity to directly compare the propulsion and performance of Janus motors at both interfaces (oil-water and solid-water) within the same setup and under similar experimental conditions. The swimming pattern and the speed values were found to be similar at the two interfaces and we conjecture an interplay of various factors such as microscale friction, lubrication, surface locking by the surfactant, reaction product absorption by oil and potential Marangoni influences for this similarity. In the next section, we designed a laminar flowing system using a square glass capillary and studied the response of a spherically symmetrical Janus micromotor in the conditions of flow. Previously, in the literature the response of Pt@SiO2, which is a model pusher-type micromotor, has been studied and they have been demonstrated to migrate cross-stream when the flow is imposed. In this thesis, we introduce a Cu@SiO2 colloid which we hypothesize to resemble a puller-type configuration based on theoretical flow field calculations. Additionally, in the literature, it has been predicted that pullers would exhibit upstream migration when placed under the conditions of flow. Indeed, when placed under flow, these particles migrate upstream, resembling many of the swimmers from biological world. These experimental findings are recovered theoretically using a simple squirmer model in puller configuration. The model also predicted a unique jumping behaviour for these particles, at very high flow rate. When increasing the flow rate in the experiments, we actually capture this characteristics. Finally, based on the theoretical flow field calculations and particularly their upstream response in the imposed flow, we conjecture a puller configuration for Cu@SiO2 micromotors. To sum up, this thesis made important advances by creating a number of different shapes of microswimmers and designing complex environments using microfluidics in which microswimmers can be placed and their response can be studied. Although, in this thesis we emphasized on Janus particles, in future, these custom-made environments can be used to assess the behaviour of other microswimmers including biological ones. While still many engineering and medical problems need to be solved before fully functional applications of artificial microswimmers are realized, manifestations of various shape designs and understanding their behaviours in complex surroundings are the first crucial steps.:Contents: Acknowledgements List of Abbreviations 1. Introduction 2. Fundamentals of active matter and microfluidics 2.1. Active matter 2.1.1. Physical fundamentals of motion at microscale 2.1.2. Biological microswimmers 2.2. Review Paper: Microfluidics for microswimmers 3. Aims and Motivation 4. Results and Discussion 4.1. Microfluidics for fabrication of microswimmers 4.1.1. Introduction 4.1.2. Droplet microfluidics 4.1.3. Stop-flow lithography 4.1.4. Paper - Fundamental Modes of Swimming Correspond to Fundamental Modes of Shape: Engineering I–, U–, and S– Shaped Swimmers 4.2. Microfluidics for specific environments: Interfaces 4.2.1. Introduction 4.2.2. Paper - Study of Active Janus Particles in the Presence of an Engineered Oil–Water Interface 4.3. Microfluidics for specific environments: Flow 4.3.1. Introduction 4.3.2. Paper - Upstream rheotaxis of catalytic Janus spheres 5. Summary and Final Remarks 6. Experimental Details 6.1. Fabrication of hydrogel particles using droplet microfluidics 6.2. Characterization of the hydrogel particles 6.3. Motion studies of the hydrogel particles A. Appendix A.1. Droplet microfluidics A.2. Stop-flow lithography A.3. Microfluidics for specific environments: Interfaces A.4. Microfluidics for specific environments: Flow B. List of publications Bibliography C. Erklärung

Made available in DSpace on 2013-08-07T19:03:50Z (GMT). No. of bitstreams: 1 000436227-Texto+Completo-0.pdf: 614510 bytes, checksum: 56faf33b6e452be763b0dd20fdfb8fe7 (MD5) Previous issue date: 2012 / BACKGROUND: The prevalence of the pusher syndrome can affect patients' motor recovery after stroke (CVA). OBJECTIVES: To establish the prevalence of pusher syndrome in patients after stroke from clinical criteria contained in Contraversive Pushing Scale (evaluation of the symptom of pushing), and correlate them with neurological abnormalities, severity of stroke and functionality. METHODS: a cross-sectional study with convenience sample of patients of both sexes with a diagnosis of acute stroke. We included patients with clinically stable and able to assess the severity of the event from the range of NIHSS, Barthel (evaluation of the symptom of pushing). To diagnose the pusher syndrome used two scoring criteria with different cutoff points, pushing the Contraversive scale: result greater than or equal to 1 (criterion I) or greater than zero (criterion II).RESULTS: 86 patients were evaluated. Of these 30 met the inclusion criteria. 17 were men with mean age of 52. 3 years. 26 patients had ischemic stroke and hemorrhagic stroke four. 14 had hemiplegia on the left and 16 right. Mean NIHSS and Barthel index were 8. 5 and 48. 8 points respectively. Using the criteria I and II prevalence rates were 3. 3% and 26. 6% respectively. The presence of pusher syndrome was significantly associated with lower values when the Barthel scale, we used the criterion II (22. 5 ± 8. 5 versus 58. 4 ± 27. 3, P <0. 001). CONCLUSIONS: The prevalence of pusher syndrome in patients after acute stroke is significant and can vary according to the criteria used. Its presence is associated with clinical severity and functional dependence, higher incidence in ischemic stroke event, parietal lobe and middle cerebral artery, respectively. / BASE TEÓRICA: A identificação da síndrome de pusher pode influir na recuperação motora dos pacientes após acidente vascular encefálico (AVC). OBJETIVOS: estabelecer a prevalência da síndrome de pusher em pacientes após AVC a partir de critérios clínicos contidos na contraversive pushing scale (avaliação do sintoma de empurrar) e correlacioná-la com anormalidades do exame neurológico, gravidade do AVC e funcionalidade. MÉTODOS: realizou-se estudo transversal com amostra de conveniência de pacientes de ambos os sexos, com diagnóstico de AVC agudo. Foram incluídos pacientes clinicamente estáveis e com possibilidade de avaliação da severidade do evento a partir da escala de NIHSS, Barthel e (avaliação do sintoma de empurrar). Para o diagnóstico da síndrome de pusher utilizaram-se dois critérios de pontuação, com diferentes pontos de corte, na contraversive pushing scale: resultado maior ou igual a 1 (critério I) ou maior que zero (critério II).RESULTADOS: foram avaliados 86 pacientes. Destes 30 preencheram os critérios de inclusão. 17 eram homens com idade média de 52,3 anos. 26 pacientes tiveram AVC isquêmico e quatro AVC hemorrágico. 14 apresentaram hemiplegia à esquerda e 16 à direita. As médias do NIHSS e do índice de Barthel foram de 8. 5 e 48. 8 pontos, respectivamente. Utilizando-se os critérios I e II as prevalências foram de 3. 3% e 26. 6%, respectivamente. A presença de síndrome de pusher associou-se significativamente a valores mais baixos na escala de Barthel quando se utilizou o critério II (22,5±8,5 versus 58,4±27,3; P< 0, 001). CONCLUSÕES: a prevalência da síndrome de pusher em paciente pós - AVC agudo é significativa e pode variar de acordo com critérios utilizados. Sua presença associa-se a parâmetros clínicos de maior gravidade e dependência funcional, maior incidência do evento em AVC isquêmico, lobo parietal e artéria cerebral média, respectivamente.

Detta är ett examensarbete på 15 högskolepoäng inom Teknisk design vid Luleå Tekniska Universitet. Arbetet har genomförts på uppdrag av Nevo Maskin AB som är en företag som utför reparationer och service av entreprenadmaskiner. Detta produktutvecklingsprojekt har genomförts i samarbete med Sigma Industry East North. Syftet med detta projekt är att förbättra och förenkla arbetet med en Trackpress. Arbetet ska göras säkrare, mobilt och mer ergonomiskt för användaren. En Trackpress används för att demontera och byta masterpinne i länken på larvkedjan på en grävmaskin. Detta arbete behandlar mellansegmentet (12-45 ton) av grävmaskiner. Verktyget som används på Nevo Maskin består av tre huvudsakliga delar: en bygel som läggs ovanpå bandet, en cylinder som expanderar med hjälp av tryckluft och en kompressor som styr tryckluften. Kompletterande delar måste användas mellan länken och cylindern för att den ska nå att pressa ut masterpinnen på länken. Verktyget väger 86 kg och kan inte hanteras av en person, utan ett lyfthjälpmedel måste användas. Ibland lyfts verktyget av två personer, men detta är ytterst oergonomiskt och medför stora risker för arbetsskador. För att förbättra detta verktyg har vi arbetat efter en designprocess där faser med förstudie, litteraturstudie, idéarbete och detaljutveckling genomförts för att utveckla ett koncept. I designprocessen som används i det här projektet är en av faserna idéarbete, där vi använt oss av workshops där medlemmarna skissar, diskuterar och skriver ned idéer som kommer fram. Genom att använda oss av olika metoder och olika grupper av människor i våra workshops kunde vi få flera infallsvinklar på problemet. Vidare har vi inom de olika faserna genomfört studiebesök, användarstudier, intervjuer, marknadsundersökning och kreativa metoder för att arbeta fram ett koncept som ritades upp i NX och Inventor. Resultatet är ett utvecklat verktyg kallat Masterpusher som består av tre delar. En ram uppbyggd av två parallella plåtar, med en platta baktill där cylindern placeras mellan de två sidoplåtarna, en domkraft för positionering av hydraulcylindern i höjdled och en insats för centrering av verktyget. I botten på ramen finns två skenor för att cylindern och domkraften inte inte ska falla ned. Ett kompletterande koncept för förflyttning och transport har rekommenderats för vidareutveckling. Konceptet medger säkrare hantering och mer ergonomiskt arbetssätt. Vikten har reducerats och materialåtgången minskats. Förbättringen innebär även en minskad produktionskostnad vilket bidrar till en konkurrensfördel jämfört med de konkurrenter som finns idag. Nyckelord:  Industridesign, Teknisk design, Konstruktion, Master pin pusher, Produktutveckling,  Ergonomi, Nevo Maskin AB / This is a bachelor degree project in Industrial design engineering at Luleå University of Technology. It has been carried out at the request of Nevo Maskin AB, a company that performs service and repairs on heavy construction equipment. The project has been executed in collaboration with Sigma Industry East North in Luleå. The purpose of this project is to improve and simplify the work with a Trackpress. The work process must be made safe, mobile and ergonomic for the user. The Trackpress is a tool that is used for dismantling and replacing the master pin in the link of the caterpillar chain on excavators. The project covers the middle segment of excavators which means excavators between 12 to 45 tons and this is the most common segment of excavators repaired by Nevo Maskin AB. The Trackpress tool used by Nevo Maskin AB consists of three parts: a frame that is placed over the caterpillar chain, a hydraulic cylinder that expands by compressed air and a compressor that controls the compressed air. Supplementary parts are needed between the link and cylinder in order for it to reach the master pin, here they use whatever they have in reach. The exciting Trackpress weighs 86 kgs and cannot be lifted by one sole person, a lifting device must be used. Sometimes two people lifts it but this is not to recommend because of the great risk of injuries. To improve the Trackpress the project has been carried out through a design process with five phases of planning, feasibility study, literature study, ideation and detail development to develop a concept. in one of the phases, Ideation, we have worked with workshops where the members draw, discuss, and write down all the ideas generated. By using different methods and groups of people in the workshops we got different angles and points of view on the problem. Furthermore we have done field trips, user studies, interviews market research and creative methods to develop a concept that was drawn in NX and Inventor. The final concept consists of three parts, a frame constructed by two parallel steel plates with another plate in the rear, a jack for positioning the cylinder, which is placed on top of the jack and between the parallel plates and a additional part for centering the tool over the chain. In the bottom there are two rails that keep the jack in place. A concept for transporting the tool has been left for future development. The concept idea gives the user safer handling of the tool and a more ergonomic way of working with it. The weight and the material consumtion has been reduced. This improvement also reduces de production cost whitch gives the company an advantage against other competitors in the same segment.   Keywords: Industrial design engineering, Master pin pusher, Construction, Product development, Ergonomics, Nevo Maskin AB

Made available in DSpace on 2015-04-14T13:35:22Z (GMT). No. of bitstreams: 1 436227.pdf: 614510 bytes, checksum: 56faf33b6e452be763b0dd20fdfb8fe7 (MD5) Previous issue date: 2011-03-23 / BACKGROUND: The prevalence of the pusher syndrome can affect patients' motor recovery after stroke (CVA). OBJECTIVES: To establish the prevalence of pusher syndrome in patients after stroke from clinical criteria contained in Contraversive Pushing Scale (evaluation of the symptom of pushing), and correlate them with neurological abnormalities, severity of stroke and functionality. METHODS: a cross-sectional study with convenience sample of patients of both sexes with a diagnosis of acute stroke. We included patients with clinically stable and able to assess the severity of the event from the range of NIHSS, Barthel (evaluation of the symptom of pushing). To diagnose the pusher syndrome used two scoring criteria with different cutoff points, pushing the Contraversive scale: result greater than or equal to 1 (criterion I) or greater than zero (criterion II).RESULTS: 86 patients were evaluated. Of these 30 met the inclusion criteria. 17 were men with mean age of 52.3 years. 26 patients had ischemic stroke and hemorrhagic stroke four. 14 had hemiplegia on the left and 16 right. Mean NIHSS and Barthel index were 8.5 and 48.8 points respectively. Using the criteria I and II prevalence rates were 3.3% and 26.6% respectively. The presence of pusher syndrome was significantly associated with lower values when the Barthel scale, we used the criterion II (22.5 ? 8.5 versus 58.4 ? 27.3, P <0.001). CONCLUSIONS: The prevalence of pusher syndrome in patients after acute stroke is significant and can vary according to the criteria used. Its presence is associated with clinical severity and functional dependence, higher incidence in ischemic stroke event, parietal lobe and middle cerebral artery, respectively. / BASE TE?RICA: A identifica??o da s?ndrome de pusher pode influir na recupera??o motora dos pacientes ap?s acidente vascular encef?lico (AVC). OBJETIVOS: estabelecer a preval?ncia da s?ndrome de pusher em pacientes ap?s AVC a partir de crit?rios cl?nicos contidos na contraversive pushing scale (avalia??o do sintoma de empurrar) e correlacion?-la com anormalidades do exame neurol?gico, gravidade do AVC e funcionalidade. M?TODOS: realizou-se estudo transversal com amostra de conveni?ncia de pacientes de ambos os sexos, com diagn?stico de AVC agudo. Foram inclu?dos pacientes clinicamente est?veis e com possibilidade de avalia??o da severidade do evento a partir da escala de NIHSS, Barthel e (avalia??o do sintoma de empurrar). Para o diagn?stico da s?ndrome de pusher utilizaram-se dois crit?rios de pontua??o, com diferentes pontos de corte, na contraversive pushing scale: resultado maior ou igual a 1 (crit?rio I) ou maior que zero (crit?rio II).RESULTADOS: foram avaliados 86 pacientes. Destes 30 preencheram os crit?rios de inclus?o. 17 eram homens com idade m?dia de 52,3 anos. 26 pacientes tiveram AVC isqu?mico e quatro AVC hemorr?gico. 14 apresentaram hemiplegia ? esquerda e 16 ? direita. As m?dias do NIHSS e do ?ndice de Barthel foram de 8.5 e 48.8 pontos, respectivamente. Utilizando-se os crit?rios I e II as preval?ncias foram de 3.3% e 26.6%, respectivamente. A presen?a de s?ndrome de pusher associou-se significativamente a valores mais baixos na escala de Barthel quando se utilizou o crit?rio II (22,5?8,5 versus 58,4?27,3; P< 0, 001). CONCLUS?ES: a preval?ncia da s?ndrome de pusher em paciente p?s - AVC agudo ? significativa e pode variar de acordo com crit?rios utilizados. Sua presen?a associa-se a par?metros cl?nicos de maior gravidade e depend?ncia funcional, maior incid?ncia do evento em AVC isqu?mico, lobo parietal e art?ria cerebral m?dia, respectivamente.

O presente trabalho aborda análises de sistemas de propulsão e manobra para comboios fluviais, e seus efeitos na manobrabilidade dos comboios. Analisam-se o sistema de propulsão convencional (propulsor mais leme), o sistema azimutal e o equipamento de proa auxiliar combinado com cada um destes sistemas de propulsão. Apresenta-se a modelagem matemática dos sistemas de propulsão e manobra citados, os quais serviram de base para implementação de um simulador computacional utilizado para obtenção dos resultados desta dissertação. As forças e momentos hidrodinâmicos são obtidos através do método das derivadas hidrodinâmicas para as simulações próximas à velocidade de serviço do comboio, enquanto para simulações em baixa velocidade utilizou um método semi-empírico baseado no princípio de cross-flow. Inicialmente, efetuou-se a validação do simulador com resultados da literatura para o caso do comboio com propulsão convencional. Em seguida, o modelo foi adaptado para os demais tipos de sistemas de propulsão e manobra propostos. Os resultados obtidos mostram que há uma maior eficiência do sistema de propulsão azimutal e do equipamento na proa para manobras em baixas velocidades, o que se torna adequado sua aplicação em comboios fluvial, pois essas embarcações navegam em velocidades menores se comparadas a outros tipos de embarcações. / The present work deal with analysis of propulsion and maneuvering systems for pusher-barge system, and results on the maneuverability of convoys. It analyzes the conventional propulsion system (rudder plus propeller), the azimuth system and combined auxiliary equipment bow with each of these propulsion systems. Presents the mathematical modeling of propulsion and maneuvering systems mentioned, which served as the basis for implementation of a computational simulator used to obtain the results of this dissertation. The hydrodynamic forces and moments are obtained by the method of hydrodynamic derivatives for simulations about service speed, while for simulations at low speed used a semi - empirical method based on the principle of cross-flow. Initially, performed the validation of the simulation results with the literature for the case of pusher-barge system with conventional propulsion. Then the model was adapted to other types of propulsion and maneuvering systems proposed. The results show that there is a greater efficiency of azimuth propulsion system and equipment in the bow to maneuver at low speeds, which makes it suitable for application in river transport, because these vessels navigate slower speeds compared to other types of vessels.

O presente trabalho aborda análises de sistemas de propulsão e manobra para comboios fluviais, e seus efeitos na manobrabilidade dos comboios. Analisam-se o sistema de propulsão convencional (propulsor mais leme), o sistema azimutal e o equipamento de proa auxiliar combinado com cada um destes sistemas de propulsão. Apresenta-se a modelagem matemática dos sistemas de propulsão e manobra citados, os quais serviram de base para implementação de um simulador computacional utilizado para obtenção dos resultados desta dissertação. As forças e momentos hidrodinâmicos são obtidos através do método das derivadas hidrodinâmicas para as simulações próximas à velocidade de serviço do comboio, enquanto para simulações em baixa velocidade utilizou um método semi-empírico baseado no princípio de cross-flow. Inicialmente, efetuou-se a validação do simulador com resultados da literatura para o caso do comboio com propulsão convencional. Em seguida, o modelo foi adaptado para os demais tipos de sistemas de propulsão e manobra propostos. Os resultados obtidos mostram que há uma maior eficiência do sistema de propulsão azimutal e do equipamento na proa para manobras em baixas velocidades, o que se torna adequado sua aplicação em comboios fluvial, pois essas embarcações navegam em velocidades menores se comparadas a outros tipos de embarcações. / The present work deal with analysis of propulsion and maneuvering systems for pusher-barge system, and results on the maneuverability of convoys. It analyzes the conventional propulsion system (rudder plus propeller), the azimuth system and combined auxiliary equipment bow with each of these propulsion systems. Presents the mathematical modeling of propulsion and maneuvering systems mentioned, which served as the basis for implementation of a computational simulator used to obtain the results of this dissertation. The hydrodynamic forces and moments are obtained by the method of hydrodynamic derivatives for simulations about service speed, while for simulations at low speed used a semi - empirical method based on the principle of cross-flow. Initially, performed the validation of the simulation results with the literature for the case of pusher-barge system with conventional propulsion. Then the model was adapted to other types of propulsion and maneuvering systems proposed. The results show that there is a greater efficiency of azimuth propulsion system and equipment in the bow to maneuver at low speeds, which makes it suitable for application in river transport, because these vessels navigate slower speeds compared to other types of vessels.

<div>In many natural and industrial processes, bubbles are exposed to surface-active contaminants (surfactants) that may cover the whole or part of the bubble interface. A partial coverage of the bubble interface results in a spontaneous self-propulsion mechanism, which is yet poorly understood.</div><div>The main goal of this study is to enhance the understanding of the flow and interfacial mechanisms underlying the self-propulsion of small surfactant contaminated bubbles. The focus is on characterizing the self-propulsion regimes generated by the presence of surface-active species, and the influence of surfactant activity and surface coverage on the active bubble motion. </div><div>The study was developed by simultaneously solving the full system of partial differential equations governing the free-surface flow physics and the surfactant transport on the deforming bubble interface using multi-scale numerical simulation. </div><div>Results show in microscopic detail how surface tension gradients (Marangoni stresses) induced by the uneven interfacial coverage produce spontaneous hydrodynamics flows (Marangoni flows) on the surrounding liquid, leading to bubble motion. Results also establish the influence of both surfactant activity and interfacial coverage on total displacement and average bubble velocity at the macroscale. </div><div>Findings from this research improve the fundamental understanding of the free-surface dynamics of self-propulsion and the associated transport of surface-active species, which are critical to important natural and technological processes, ranging from the Marangoni propulsion of microorganisms to the active motion of bubbles and droplets in microfluidic devices. Overall, the findings advance our understanding of active matter behavior; that is, the behavior of material systems with members able to transduce surface energy and mass transport into active movement.</div>