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.

Pythium diseases are common in the greenhouse production of tobacco transplants and can cause up to 70% seedling loss in hydroponic (float-bed) greenhouses. However, the symptoms and consequences of Pythium diseases are often variable among these greenhouses. A tobacco transplant greenhouse survey was conducted in 2017 in order to investigate the sources of this variability, especially the composition and distribution of Pythium communities within greenhouses. The survey revealed twelve Pythium species. Approximately 80% of the surveyed greenhouses harbored Pythium in at least one of four sites within the greenhouse, including the center walkway, weeds, but especially bay water and tobacco seedlings. Pythium dissotocum, followed by P. myriotylum, were the most common species. Pythium myriotylum, P. coloratum, and P. dissotocum were aggressive pathogens that suppressed seed germination and caused root rot, stunting, foliar chlorosis, and death of tobacco seedlings. Pythium aristosporum, P. porphyrae, P. torulosum, P. inflatum, P. irregulare, P. catenulatum, and a different isolate of P. dissotocum, were weak pathogens, causing root symptoms without affecting the upper part of tobacco seedlings. Pythium adhaerens, P. attrantheridium, and P. pectinolyticum did not affect tobacco seeds or seedlings. The consequences of Pythium infection were more likely to be severe when they occurred during seed germination than at seedling emergence, or after plant stem elongation when seedling roots had started to grow into underlying nutrient solutions, depending on the species of Pythium. High and low variation was observed among isolates of P. dissotocum and P. myriotylum, respectively. Pythium myriotylum co-existed with multiple other Pythium or oomycete species in the same environments within tobacco greenhouses, and significant in vitro and/or in vivo interactions between P. myriotylum and some naturally co-existing species were revealed. Pythium porphyrae may have the potential to protect tobacco seeds and seedlings from P. myriotylum infection. Greenhouse Pythium control trials identified ethaboxam, mefenoxam, and copper ionization as potentially promising alternatives to etridiazole for Pythium disease management in tobacco transplant production. The outcomes of this project provide useful new information to better understand the composition, distribution, and diversity of Pythium communities in tobacco transplant greenhouses and to improve Pythium disease management for tobacco transplant production. / Doctor of Philosophy / Pythium diseases are common in tobacco transplant production and can cause up to 70% seedling losses in hydroponic (float-bed) tobacco transplant greenhouses. However, little is known about the composition and distribution of Pythium communities in tobacco transplant greenhouses. This project began with a tobacco transplant greenhouse survey, in which 12 Pythium species were recovered from center walkways, weeds, greenhouse bay water, and tobacco seedlings. Pythium dissotocum and P. myriotylum were the two types (species) of Pythium most commonly found in the survey. Pythium myriotylum, P. coloratum, and P. dissotocum were aggressive pathogens that suppressed seed germination and caused root rot, stunting, foliar chlorosis, and death of tobacco seedlings. Pythium aristosporum, P. porphyrae, P. torulosum, P. inflatum, P. irregulare, P. catenulatum, and an isolate of P. dissotocum, were weak pathogens causing root symptoms without affecting the upper part of tobacco seedlings. Pythium adhaerens, P. attrantheridium, and P. pectinolyticum did not affect tobacco seeds or seedlings. The symptoms caused by infection by Pythium species differed among host (tobacco) growth stages, except for the most aggressive species, P. myriotylum. High levels of variation were observed among isolates of P. dissotocum, in terms of vegetative growth rate (on V8 agar media) and aggressiveness on tobacco seed and seedlings. Pythium myriotylum was found to co-exist with multiple other Pythium or oomycete species (neighbor isolates) in the same environments within tobacco greenhouses. Significant interactions between P. myriotylum and some neighbor isolates were revealed, and these interactions significantly affect the consequences of P. myriotylum infection of tobacco seeds. Greenhouse Pythium control trials identified two chemical water treatments (ethaboxam and mefenoxam), and a non-chemical water treatment (copper ionization) as potentially promising alternatives to the current standard Pythium control (etridiazole) for Pythium disease management in tobacco transplant production. The outcomes of this project provide useful new information to both better understand the composition, distribution, and diversity of Pythium communities in tobacco transplant greenhouses and to improve Pythium disease management for tobacco transplant production.