Microsieves are permeable membranes with excellent properties for filtration applications. In this thesis the inkjet-technology is applied (1) to manufacture micro-porous microsieves, and (2) to reinforce the mechanical stability of float-cast, nano-porous microsieves: (1) The current process for inkjet-printed microsieves includes a manual step which is substituted by inkjet printing in order to increase the level of automation. The obtained microsieves are characterized regarding the pore size distribution. Effects which occur during the manufacture and broaden the pore size distribution are identified. Based on the results, the process is improved to obtain fully inkjet-printed microsieves with a narrowed pore size distribution. (2) The mechanical stability of fragile, float-cast microsieves is improved by the application of inkjet-printed reinforcement patterns on top of the microsieves. A machine is built to combine both technologies of float-casting and inkjet printing. The printing process is improved to manufacture reinforcement patterns of well-defined geometry. / Mikrosiebe sind permeable Membranen mit herausragenden Eigenschaften für die Anwendung in der Filtration. In der vorliegenden Dissertation wird die Inkjet-Drucktechnologie angewandt, um (1) mikroporöse Mikrosiebe herzustellen und (2) nanoporöse Mikrosiebe mechanisch zu stabilisieren: (1) Die Herstellung von Mikrosieben mittels Inkjet-Druck beinhaltet momentan einen manuellen Schritt, der durch einen Inkjet-Druckschritt ersetzt wird, um den Automatisierungsgrad des Verfahrens zu erhöhen. Die Mikrosiebe werden bezüglich der Porengrößenverteilung untersucht. Auftretende Effekte, die die Porengrößenverteilung verbreitern, werden identifiziert. Aus den Resultaten dieser Analyse wird der Prozess optimiert, um Mikrosiebe mit einer engen Porengrößenverteilung herzustellen. (2) Die mechanische Stabilität von fragilen Mikrosieben, die mittels Float-Casting hergestellt werden, wird durch das Aufbringen einer Stützstruktur mittels Inkjet-Druck verstärkt. Ein Maschinensetup wird aufgebaut um beide Technologien des Float-Castings und des Inkjet-Drucks zu kombinieren. Weiterhin wird der Prozess dahingehend optimiert, Stützstrukturen mit wohl-definierten Parametern zu erzielen.

The purpose of this study was to examine how preschool children, 4-5 years, think, reason and explain an everyday physical phenomena. The phenomenon’s that was chosen for this study is the Archimedes principle and density. The study was conducted through qualitative semi-structured interviews that took place while the experiments were carried out by the children. This method was chosen to make it possible to follow the children´s reasoning about the subject of physics in preschool and to let them lead the conversation and let them explain the result. The result shows that children in the study have experience and knowledge about the phenomenon of why objects float or sink. Even if they don’t have knowledge of Archimedes´ principle or density, they can come up with their own conclusions of why objects float or sink, based on their past experiences and knowledge. Some of the children approach an explanation of these phenomena, without using the scientific concepts. / Syftet med studien är att undersöka hur förskolebarn, 4-5 år, tänker, resonerar och förklarar vardagliga fysikaliska fenomen. Fenomenen som valts till denna studie är Arkimedes princip och densitet. Genomförandet av studien bygger på kvalitativa semistrukturerade intervjuer som genomfördes i samband med att experimentet utfördes. Metoden valdes för att undvika att barnen bara svarade ja eller nej på frågorna, utan det skulle finnas utrymme och möjlighet för barnen att förklara sina tankar och idéer. I denna studie var barnens tankar det viktiga och intressanta, hur de resonerade och förklarade fenomenet. Resultatet visar att barnen i studien har erfarenhet och kunskap om fenomenet varför föremål flyter eller sjunker. Även om de inte har kunskap om Arkimedes princip eller densitet kan de komma med egna slutsatser till varför föremål flyter eller sjunker, baserat på deras tidigare erfarenheter och kunskaper, och några barn närmar sig en förklaring av dessa fenomen, utan att använda sig av de vetenskapliga begreppen.

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2015-07-02T18:04:52Z No. of bitstreams: 2 Alexsandro Lopes.pdf: 865523 bytes, checksum: 8887e54580cd40a029856f7755bfff87 (MD5) Alexsandro Lopes.pdf: 865523 bytes, checksum: 8887e54580cd40a029856f7755bfff87 (MD5) / Made available in DSpace on 2015-07-02T18:04:52Z (GMT). No. of bitstreams: 2 Alexsandro Lopes.pdf: 865523 bytes, checksum: 8887e54580cd40a029856f7755bfff87 (MD5) Alexsandro Lopes.pdf: 865523 bytes, checksum: 8887e54580cd40a029856f7755bfff87 (MD5) Previous issue date: 2012-05-17 / Nenhuma / A Governança Corporativa pode ser entendida como o conjunto de mecanismos de incentivo e controles, internos e externos, que visam minimizar os custos decorrentes do problema de agência. O tema é importante em vista da ampla difusão da hipótese de que as práticas de Governança afetam o valor e o desempenho das empresas. A dissertação investiga se a estrutura de governança corporativa foi relevante para as companhias abertas brasileiras no período de 2000 a 2010 e se as companhias com práticas de governança adequadas às recomendações do IBGC e da CVM alcançaram maior valor de mercado ou melhor desempenho. Foram consideradas cinco variáveis de governança: segregação nos cargos de diretor executivo e presidente do conselho (SC), tamanho do conselho (TOT), independência do conselho (INDEP), adesão aos níveis de governança corporativa (GC) e ações livres ou “free float” (FF). Aplicando técnicas de dados em painel entre as variáveis dependentes de valor e desempenho e as variáveis independentes de governança corporativa, a variável (SC) apresentou forte evidência de que, em média, empresas que tiveram pessoas distintas ocupando os cargos de diretor executivo e presidente do conselho foram mais valorizadas pelo mercado. Contrariando a situação esperada, em relação à variável de independência do conselho (INDEP) as empresas com grau de independência mais elevado tiveram desempenho financeiro inferior às demais. A variável free float apresentou correlação negativa com o valor das empresas. A variável de adesão aos níveis de governança corporativa (GC) e tamanho do conselho (TOT) não apresentaram relação estatística significativa com as variáveis de valor e desempenho. / Corporate governance can be understood as a set of incentive and controls mechanisms, internal and external, which aim to minimize the costs of the problems arising from the agency. The issue is important because it is widely held assumption that governance practices affect the value and of the performance company. This thesis investigates whether the corporate governance structure was relevant to Brazilian companies from 2000 to 2010 and the recommendations of the appropriate companies and CVN IBGC achieved higher market value or performance. Five variables were considered Governance: segregation in the positions of CEO and chairman (SC), board size (TOT), board independence (INDEP), the membership levels of Corporate Governance (CG) and free actions or "free float "(FF). Applying techniques of panel data between the dependent variables of value and performance and the independent variables of corporate governance, the variable (SC) presented strong evidence that, on average, companies that had different people holding the positions of CEO and chairman, were most valued by the market. Contrary to the expected situation in relation to variable board independence (INDEP) companies with higher degree of independence had financial performance lower than the others. The free float variable was negatively correlated with the value of companies. The variable levels of adherence to corporate governance (CG) and board size (TOT) showed no statistically significant relationship against the variables of value and performance.

Motivated by operational issues in real-world glass manufacturing, this thesis addresses a problem of laying out and sequencing the orders so as to minimize wasted glass, called scrap. This optimization problem combines aspects of traditional cutting problems and traditional scheduling and sequencing problems. In so far as we know, the combination of cutting and scheduling has not been modeled, or solved. We propose a two-phase approach: snap construction and constructing cutting and offload schedules. Regarding the second phase problem, we introduce FGSP (float glass scheduling problem), and provide its solution structure, called coveys. We analyze simple sub-models of FGSP considering the main elements: time, unit, and width. For each model, we provide either a polynomial time algorithm or a proof of NP-completeness. Since FGSP is NP-complete, we propose a heuristic algorithm, Longest Unit First (LUF), and analyze the worst case performance of the algorithm in terms of the quality of solutions; the worst case performance bound is {1+(m-1)/m}+{1/3-1/(3m)} where m is the number of machines. It is 5/3 when m=2. For the real-world problem, we propose two different methods for snap construction, and we apply two main approaches to solve cutting and offloading schedules: an MIP approach and a heuristic approach. Our solution approach produces manufacturing yields greater than 99%; current practice is about 95%. This is a significant improvement and these high-yield solutions can save millions of dollars.

In order to liquidate a large position in an asset, investors face a tradeoff between price volatility and market impact. The classical approach to this problem is to model volatility via a Brownian motion, and separate price impact into its permanent and temporary components. In this thesis, we consider two variations of the Chriss-Almgren model for temporary price impact. The first model investigates the infinite-horizon optimal liquidation problem in a market with float-dependent, nonlinear temporary price impact. The value function of the investor’s basket and the optimal strategy are characterized in terms of classical solutions of nonlinear parabolic partial differential equations. Depending on the price impact parameters, liquidation may require finite or infinite time. The second model considers time-varying market depth, in that intense trading increases temporary price-impact, which otherwise reverts to a long-term level. We find the optimal execution policy in a finite horizon for an investor with constant risk aversion, and derive the solution using calculus of variation techniques. Although the model potentially allows for price manipulation strategies, these policies are never optimal. We study the non time-constrained case as a limit to the finite-horizon case and explain the solution through a quasi-linear PDE.

Syftet med studien var att undersöka barns tankar kring varför olika föremål flyter eller sjunker i olika vätskor. Åtta förskolebarn mellan fem och sex år deltog i undersökningen. Barnen intervjuades i mindre grupper i samband med att de genomförde ett experiment kring densitet. Resultatet visar att barnen framförallt förklarar att vätskorna flyter på varandra för att de har olika vikt och olika egenskaper. Att föremålen flyter på olika ställen förklarar de också med att föremålen har olika vikt, men även med att föremålen fastnar eller att storleken bestämmer om föremålet flyter eller sjunker i vätskorna. Studien visar att barnen har många olika tankar kring varför något flyter eller sjunker men de har inte en korrekt vetenskaplig förklaring till fenomenet. Däremot har de sannolikt erövrat andra kunskaper och erfarenheter som de kan återkomma och relatera till vid andra tillfällen. Genom att synliggöra barnens tankar, blir det troligtvis lättare att som pedagog i förskolan stötta barnens utveckling och lärande. / The aim of the study was to investigate children’s thoughts about objects flotation in different liquids. Eight preschool children aged five to six years were included in the study. Qualitative interviews in small groups have been conducted with the children in an experiment on density. The result shows that the children explained the liquids flotation due to differences in weight and different characteristics. Furthermore, the objects flotation was also explained with the objects weight, but also that the objects can get stuck or that size of the object decides whether it will float or sink in the liquids. The study shows that the children have many thoughts about why some objects floats and some will sink, but they don’t have a proper scientific explanation for the phenomenon. On the other hand, they probably received other skills and experiences that they can return and relate to in other situations. By studying the children's thoughts, it probably will be easier to support children's development and learning as an educator in preschool.

Content: The aim of this desk study is to compare consumption of thermal energy in temperate vs. (sub)tropical climate for two representative processes: float heating (bating and dyeing) and chamber drying, with the view of contributing towards overall assessment of thermal energy consumption for tanneries operating under rather different conditions. The energy consumption is calculated for 1 t of wet salted hides and assuming that 1000 kg of wet salted weight corresponds to 1100 kg of pelt weight containing 838 kg of water and 262 kg of collagen subsequently segregated into grain leather and usable splits. Float rates (200% on pelt/shaved weight), average inlet water temperatures (15 oC vs. 25 oC), process float temperatures for bating (35 oC) and dyeing (60 o C) have been defined. Similarly, for computation of thermal energy for chamber drying, identical initial (45 %) and target leather humidity (20 %) are set and average respective fresh air temperature (15 oC vs. 30 oC) and fresh air relative humidity (50% vs. 70%) estimated and operating conditions such as exhaust air temperature and relative humidity defined. Based on such parameters and assumptions, specific ratios for thermal energy consumption for float heating (bating & dyeing) and for chamber drying have been calculated and comparisons made; the results might not quite coincide with common perceptions. The energy needs computed are net amounts, i.e. regardless of the source and without taking into account any losses and disregarding energy consumption for ambient heating and/or cooling. Thus, the total energy needs are much higher. The ratios computed for grain leather are valid for split leather as well. However, if the solar energy is used to support water heating, the conditions in the tropic zone are substantially more favourable, due to higher insolation and higher efficiency factor (i.e. difference of the final vs. inlet water temperature). Take-Away: Based on such parameters and assumptions, specific ratios for thermal energy consumption for float heating (bating & dyeing) and for chamber drying have been calculated and comparisons made; the results might not quite coincide with common perceptions. However, if the solar energy is used to support water heating, the conditions in the tropic zone are substantially more favourable, due to higher insolation and higher efficiency factor (i.e. difference of the final vs. inlet water temperature).

My master´s thesis deals with the design of amphibian hull for VUT 001 Marabu aircraft. Part of this work is aerodynamic and hydrodynamics design of hull including flight mechanics with, take of and landing on the water. The last point of work is load calculation of float and landing gear and design of landing gear retraction mechanics.

Diplomová práce se zabývá modifikací stávající pozemní verze letounu EV-55 pro možnost přistání na vodní hladině. Snahou je najít takovou variantu, která nepovede k výrazným konstrukčním zásahům do draku letounu a bude vyhovovat stavebnímu předpisu CS 23, zejména požadavkům týkající se plovatelnosti a stability na vodě. Je proveden hmotový rozbor modifikované verze a s tím související omezení hmotové obálky a rozsahu centráží. Zatížení od vody je spočítáno v souladu s CS 23. Pro toto zatížení je následně navrhnuto konstrukční řešení uchycení plováků k trupu a provedena pevnostní kontrola jednotlivých prvků a spojovacích uzlů. Tyto hodnoty jsou dále porovnány s pozemními případy zatížení a stanoveny součinitele rezerv. V závěru jsou spočítány letové výkony: maximální horizontální rychlost, stoupavost, dolet a vytrvalost.

This master’s thesis deals with the design of installation of floats for the M-4 Irbis airplane and it’s modification in aim to provide water level landing. Part of this thesis is selection of geometry of floats, weight analysis of the modified version and stress analysis of structural elements. The aim was to perform modification on a float plane which will have a minimal impact on the airframe and to meet the requirements of Certification Specification ASTM F2245 and CS-VLA. In conclusion, the hydrodynamic and aerodynamic characteristics including flight performance is determined. Final part is devoted to the design of the rudder for directional control of the floats.