Turbulenssimallien soveltuminen syklonien numeeriseen virtauslaskentaan

Tässä työssä tutkittiin miten totuudenmukaisia tuloksia syklonierottimen virtauskentästä saadaan numeerisella laskennalla, kun käytetään eri turbulenssimalleja. Tarkoitus oli myös selvittää yleisesti syklonin toimintaperiaatteita, haasteita sen käytössä sekä syklonin numeerisen virtauslaskennan perusteita. Numeerisen virtauslaskennan teoria selitetään pääpiirteittäin, samoin turbulenssin mallinnus. Työn laskentaosiossa simuloitiin Fluent-ohjelmalla syklonin virtauskenttää kuumalla ilmalla sekä kahdella eri turbulenssimallilla ja verrattiin tuloksia kirjallisuudesta löytyviin mittaustuloksiin. Simuloinnit suoritettiin sekä ajasta riippuvana että ajasta riippumattomana ja kahdella eri laskentahilalla. Simulointien tulokset osoittivat, että RNG k-ε turbulenssimalli ei kykene tuottamaan totuu-denmukaista virtauskenttää. Toisen käytetyn turbulenssimallin, Reynolds-jännitysmallin tulokset vastasivat enemmän mittaustuloksia. Reynolds-jännitysmallia voidaan pitää käyttökelpoisena syklonin simuloinnissa tämän työn ja kirjallisuuden perusteella. Mallissa oli yksinkertaistuksia, esimerkiksi kiinteää ainetta ei otettu huomioon lainkaan.

Tendering: optimization and rationality

There have been various techniques published for optimizing the net present value of tenders by use of discounted cash flow theory and linear programming. These approaches to tendering appear to have been largely ignored by the industry. This paper utilises six case studies of tendering practice in order to establish the reasons for this apparent disregard. Tendering is demonstrated to be a market orientated function with many subjective judgements being made regarding a firm's environment. Detailed consideration of 'internal' factors such as cash flow are therefore judged to be unjustified. Systems theory is then drawn upon and applied to the separate processes of estimating and tendering. Estimating is seen as taking place in a relatively sheltered environment and as such operates as a relatively closed system. Tendering, however, takes place in a changing and dynamic environment and as such must operate as a relatively open system. The use of sophisticated methods to optimize the value of tenders is then identified as being dependent upon the assumption of rationality, which is justified in the case of a relatively closed system (i.e. estimating), but not for a relatively open system (i.e. tendering).

Fluidez nos mundos virtuais: a participação nas comunidades virtuais do Second Life como forma de potencializar a experiência de consumo

Incrementar o conhecimento sobre o que contribui efetivamente para que ocorram interações bem sucedidas entre websites e os consumidores online, mais especificamente no mercado crescente dos mundos virtuais, é um assunto relevante para os pesquisadores e profissionais de administração de empresas. Vivemos em uma nova etapa da cultura do consumo, onde a experiência de consumo ganha relevância. Os jogos online, ambientados em mundos virtuais, são ilustrações muito apropriadas para representar a emergência do Marketing de Experiência, característico desta etapa. Os mundos virtuais, como o Second Life, podem ser classificados como “mundos de experiência”, e uma das suas principais características é a existência de comunidades virtuais. A interação entre usuários e o relacionamento social é fundamental para o enriquecimento da experiência de consumo nos mundos virtuais. A teoria da fluidez é um dos constructos mais utilizados para entender o comportamento do consumidor na internet e uma das formas de definir a natureza de experiências de consumo na internet. A utilização deste modelo (que vem sendo utilizado e aprimorado nos últimos 14 anos) é aconselhada para definir e medir a experiência de consumo na internet. A participação em comunidades virtuais pode ser um dos fatores que enriquecem a experiência de consumo nos mundos virtuais, percebida pela fluidez. O objetivo desta dissertação é entender se a participação em comunidades virtuais potencializa a experiência de consumo em mundos virtuais sociais, em especial no Second Life, tomando como base o conceito da fluidez. O objeto de estudo foram as comunidades virtuais do Second Life, durante o período da pesquisa que ocorreu entre o final de julho e o início de novembro de 2010. Para fazer a pesquisa de campo, empírica e exploratória, foi utilizada a metodologia da netnografia (etnografia virtual), descritiva por definição, como forma de atingir o objetivo proposto. Netnografia é a rigorosa e sistemática adaptação da etnografia especificamente alterada para as contingências do comportamento e interação online, isto é, ao estudo das comunidades virtuais. As atividades de pesquisa foram realizadas com observação participativa, isto é, com a participação, pelo pesquisador, no cotidiano do mundo virtual Second Life, que vivenciou, como um novato, a experiência de consumo em si. A dissertação aqui apresentada é o resultado do engajamento do pesquisador em uma imersão nas comunidades virtuais do Second Life. Foi concluído que experiência de consumo nos mundos virtuais é enriquecida pela participação em comunidades virtuais. A fluidez – percebida pela telepresença (imersão), perda de noção de tempo, envolvimento, prazer e diversão – é uma sensação que pode ser considerada típica e freqüente dos mundos virtuais e potencializada pela participação em comunidades virtuais. A participação em comunidades virtuais permite que os usuários vivenciem uma experiência rica, que seja ativa, responsiva, interativa e participativa, o que potencializa a experiência de consumo nos mundos virtuais.

Dançando com gatos e passáros: O movimento ecossistêmico da ludopoiese na educação infantil

This study shows the movement of educators ludopoiese ecosystem of the Center for Early Childhood Education Marise Paiva-CEIMAP. We used the metaphorof dance as an opportunity to stimulate scientific creativity. Ecosystem Thought, complex thinking, the theory of autopoiesis and Flow Theory, constituted the main theoretical steps to understand the phenomenon of ludopoiese, from the look of your totalidadem with the following objectives: 1 - Identify and interpret the process of self ludopoiética CEIMAP of Early Childhood Educators in the actions of the play, care for and educate in school life; 2 - Analyze Ecosystem Thought from ludopoiéticos how these processes affect and / or possible changes and transformations in practice humanescenteseducational CEIMAP. The theoretical metodógicos steps to address the proposed objectives are grounded in existential action research part of the appreciation of the complexity of the real, considering the human being a whole dynamic. In this sense the game of sand, recreational experiences, the systematic studies and video training were explored with a view to the transdisciplinary relevance of everyday phenomena. New knowledge acquired in accordance with the directions given indicating the movement of the ecosystem studied ludopoiese educators, involved in four main streams: love, play, care for and raise it from love streamline interdependently. The ludopoiese eachteacher would then be fed by this web generated by love that permeates all other educational activities, nurturing and maintaining a constant creative self-organization of knowledge and know-how to be teachers. Thus, every network that generates andstream lines the system emerges ludopoiético biology of love, the open dialogue and playing in the wishing well to the student, the aesthetic beauty of caring and educating, as a human conditionand relevant as possible to live / live not only in teaching children, but in other educational contexts of teaching and teacher education

Proposição de um modelo para análise de fluxo de carga, curto-circuito e simulação de relés de produção

The objective of the present work is develop a model to simulate electrical energy networks in transient and stead states, using the software ATP (Alternative Transient Program), able to be a way to join two distinct themes, present in classical methodology planning networks: short circuit analysis and load flow theory. Beyond that, using a tool for relay simulation, this paper intend to use the new developed model to investigate the influence of transient phenomenon in operation of protection relays, and calibrate the enterprise's protections relays. For testing the model, some relays, actually, installed at COSERN were used

A mass-transportation approach to a one dimensional fluid mechanics model with nonlocal velocity

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Latent hardening size effect in small-scale plasticity

We aim at understanding the multislip behaviour of metals subject to irreversible deformations at small-scales. By focusing on the simple shear of a constrained single-crystal strip, we show that discrete Dislocation Dynamics (DD) simulations predict a strong latent hardening size effect, with smaller being stronger in the range [1.5 µm, 6 µm] for the strip height. We attempt to represent the DD pseudo-experimental results by developing a flow theory of Strain Gradient Crystal Plasticity (SGCP), involving both energetic and dissipative higher-order terms and, as a main novelty, a strain gradient extension of the conventional latent hardening. In order to discuss the capability of the SGCP theory proposed, we implement it into a Finite Element (FE) code and set its material parameters on the basis of the DD results. The SGCP FE code is specifically developed for the boundary value problem under study so that we can implement a fully implicit (Backward Euler) consistent algorithm. Special emphasis is placed on the discussion of the role of the material length scales involved in the SGCP model, from both the mechanical and numerical points of view.

Latent hardening size effect in small-scale plasticity

We aim at understanding the multislip behaviour of metals subject to irreversible deformations at small-scales. By focusing on the simple shear of a constrained single-crystal strip, we show that discrete Dislocation Dynamics (DD) simulations predict a strong latent hardening size effect, with smaller being stronger in the range [1.5 µm, 6 µm] for the strip height. We attempt to represent the DD pseudo-experimental results by developing a flow theory of Strain Gradient Crystal Plasticity (SGCP), involving both energetic and dissipative higher-order terms and, as a main novelty, a strain gradient extension of the conventional latent hardening. In order to discuss the capability of the SGCP theory proposed, we implement it into a Finite Element (FE) code and set its material parameters on the basis of the DD results. The SGCP FE code is specifically developed for the boundary value problem under study so that we can implement a fully implicit (Backward Euler) consistent algorithm. Special emphasis is placed on the discussion of the role of the material length scales involved in the SGCP model, from both the mechanical and numerical points of view.

Aerodynamic external pressure loads on a semi-circular bluff body under wind gusts

This brief communication concerns the unsteady aerodynamic external pressure loads acting on a semi-circular bluff body lying on a floor under wind gusts and describes the theoretical model, experimental setup, and experimental results obtained. The experimental setup is based on an open circuit, closed test section, low speed wind tunnel, which includes a sinusoidal gust generating mechanism, designed and built at the Instituto de Microgravedad “Ignacio Da Riva” of the Universidad Politécnica de Madrid (IDR/UPM). Based on the potential flow theory, a theoretical model has been proposed to analyse the problem, and experimental tests have been performed to study the unsteady aerodynamic loads on a semi-circular bluff body. By fitting the theoretical model predictions with the experimental results, influencing parameters of the unsteady aerodynamic loads are ascertained. The values of these parameters can help in clarifying the phenomenon of the external pressure loads on semi-circular bluff body under various gust frequencies. The theoretical model proposed allows the pressure variation to be split into two contributions, a quasi-steady term and an unsteady term with a simple physical meaning

Combining the power of online crowdsourcing with creative writing user interfaces

The goal of this work was to provide professional and amateur writers with a new way of enhancing their productivity and mental well-being, by helping them overcoming writers block and being able to achieve a state of optimal experience while writing. Our approach is based on bringing together different components to create what we call a creative moment. A creative moment is composed by an image, a text, a mood, a location and a color. The color presented in the creative moment varied according to the mood that was associated to the creative moment. With the creative moments we hoped that our users could have a way to easily trigger their creativity and have a kick start in their work. The prototyping of a web crowdsourcing platform, named CreativeWall, and a Microsoft Word Add-In, that was used on the user study performed, is described and their implementations are discussed. The user study reveals that our approach does have a positive influence in the productivity of the participants when compared with another existing approach. The study also revealed that our approach can ease the process of achieving a state of optimal experience by enhancing one of the dimensions presented on the Flow Theory. At the end we present what we consider would be some possible future developments for the concept created during the development of this work.

Prediction of steady-state flux through variably saturated zones within a septic absorption trench

This paper describes effluent flow dynamics within a septic absorption system and the prediction of flow through the biomat and sub-biomat zone. Using soil hydraulic properties in a one dimensional model we demonstrate how soil hydraulic properties interact with biomat resistances to determine long-term acceptance rate (LTAR). The LTAR is a key parameter used in the Australian and New Zealand Standard AS1547:2000 to calculate the area of trench required to ensure trenches are not overloaded. Results show that several orders of magnitude variation in saturated hydraulic conductivity (Ks) collapse to a one order of magnitude variation in LTAR. These results are calculated from a model using basic flow theory, allowing LTAR to be estimated for any combination of biomat resistance and soil hydraulic properties. To increase the reliability of prediction of septic trench hydrology, HYDRUS 2D was used to model two dimensional flow. For more permeable soils, the exfiltration zone above sidewall biomat growth is shown to be a key pathway for excess effluent flow.

Combining the power of online crowdsourcing with creative writing user interfaces

The goal of this work was to provide professional and amateur writers with a new way of enhancing their productivity and mental well-being, by helping them overcoming writers block and being able to achieve a state of optimal experience while writing. Our approach is based on bringing together different components to create what we call a creative moment. A creative moment is composed by an image, a text, a mood, a location and a color. The color presented in the creative moment varied according to the mood that was associated to the creative moment. With the creative moments we hoped that our users could have a way to easily trigger their creativity and have a kick start in their work. The prototyping of a web crowdsourcing platform, named CreativeWall, and a Microsoft Word Add-In, that was used on the user study performed, is described and their implementations are discussed. The user study reveals that our approach does have a positive influence in the productivity of the participants when compared with another existing approach. The study also revealed that our approach can ease the process of achieving a state of optimal experience by enhancing one of the dimensions presented on the Flow Theory. At the end we present what we consider would be some possible future developments for the concept created during the development of this work.

Simulação numérica do escoamento monofásico em uma bomba centrífuga radial

Centrifugal pumps are vastly used in many industrial applications. Knowledge of how these components behave in several circumstances is crucial for the development of more efficient and, therefore, less expensive pumping installations. The combination of multiple impellers, vaned diffusers and a volute might introduce several complex flow characteristics that largely deviate from regular inviscid pump flow theory. Computational Fluid Dynamics can be very helpful to extract information about which physical phenomena are involved in such flows. In this sense, this work performs a numerical study of the flow in a two-stage centrifugal pump (Imbil ITAP 65-330/2) with a vaned diffuser and a volute. The flow in the pump is modeled using the software Ansys CFX, by means of a multi-block, transient rotor-stator technique, with structured grids for all pump parts. The simulations were performed using water and a mixture of water and glycerin as work fluids. Several viscosities were considered, in a range between 87 and 720 cP. Comparisons between experimental data obtained by Amaral (2007) and numerical head curves showed a good agreement, with an average deviation of 6.8% for water. The behavior of velocity, pressure and turbulence kinetic energy fields was evaluated for several operational conditions. In general, the results obtained by this work achieved the proposed goals and are a significant contribution to the understanding of the flow studied.

Determination of regional flow by use of intravascular PET tracers: Microvascular theory and experimental validation for pig livers

Today, the standard approach for the kinetic analysis of dynamic PET studies is compartment models, in which the tracer and its metabolites are confined to a few well-mixed compartments. We examine whether the standard model is suitable for modern PET data or whether theories including more physiologic realism can advance the interpretation of dynamic PET data. A more detailed microvascular theory is developed for intravascular tracers in single-capillary and multiple-capillary systems. The microvascular models, which account for concentration gradients in capillaries, are validated and compared with the standard model in a pig liver study. Methods: Eight pigs underwent a 5-min dynamic PET study after O-15-carbon monoxide inhalation. Throughout each experiment, hepatic arterial blood and portal venous blood were sampled, and flow was measured with transit-time flow meters. The hepatic dual-inlet concentration was calculated as the flow-weighted inlet concentration. Dynamic PET data were analyzed with a traditional single-compartment model and 2 microvascular models. Results: Microvascular models provided a better fit of the tissue activity of an intravascular tracer than did the compartment model. In particular, the early dynamic phase after a tracer bolus injection was much improved. The regional hepatic blood flow estimates provided by the microvascular models (1.3 +/- 0.3 mL min(-1) mL(-1) for the single-capillary model and 1.14 +/- 0.14 min(-1) mL(-1) for the multiple-capillary model) (mean +/- SEM mL of blood min(-1) mL of liver tissue(-1)) were in agreement with the total blood flow measured by flow meters and normalized to liver weight (1.03 +/- 0.12 mL min(-1) mL(-1)). Conclusion: Compared with the standard compartment model, the 2 microvascular models provide a superior description of tissue activity after an intravascular tracer bolus injection. The microvascular models include only parameters with a clear-cut physiologic interpretation and are applicable to capillary beds in any organ. In this study, the microvascular models were validated for the liver and provided quantitative regional flow estimates in agreement with flow measurements.