This thesis report describes how to improve the control of the temperature in a Powder Bed Fusion 3D printer. This is accomplished by first creating a model ofthe thermal system. To create a good model, both black-box and grey-box models of the system are estimated and compared. Based on the best model, different control designs are examined and the results are compared to find the control design yielding the best results. The system being modelled is a multiple input multiple output system with acomplex internal structure. The modelling can be divided into several steps. Firstly, data has to be acquired from the system. Secondly, the data is analysed and processed. Thirdly, models are estimated based on the collected data. Different model structures such as state-space, ARX, ARMAX, Output Error, Box Jenkins and grey-box models are examined and compared to each other. Finally, the different derived models are validated and it turns out the ARMAX model yields the best prediction capabilities. However, when the controllers were tested on the actual system the controllers that are based on the grey-box model yield the best results. The different control designs examined in this work are diagonal PI controllers, decoupled PI controllers, feed forward controllers, IMC controllers and statefeedback controllers. The controllers are all based on the derived models. The controllers are implemented into a code structure capable of communicating with the printers. Here, tests of the performance for the different controllers on the actual system are executed. The results show that a non-linear system can be controlled using linear controllers. However, introducing some fuzzy control elements such as limiting the controllers to only be used within small temperature intervals and using a fixed input outside this interval yield better results. From these results, the best linear controller is a diagonal PI controller tuned from a grey-box model with as many states as there are controllable areas of the powder bed. The improvement is only marginal compared to the original PI controller, reinforcing the conclusion that some non-linear strategies are needed in the controller in order to achieve significant improvements.

Orientador: Flavio Luis Schmdit / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-26T04:59:10Z (GMT). No. of bitstreams: 1 Scucuglia_Marcio_M.pdf: 2766345 bytes, checksum: df718c4c465f3ea8e35d990cbd5ffbc6 (MD5) Previous issue date: 2014 / Resumo: Tanques assépticos são equipamentos aplicados em linhas de processamento de produtos longa-vida, com o objetivo de estocar o produto previamente esterilizado até o envase asséptico, mantendo a condição de esterilidade comercial obtida nas etapas anteriores. Para evitar a recontaminação do produto, o equipamento deve ser levado a condição de esterilidade, sendo aplicado um procedimento de aquecimento, desaeração e esterilização. Por ser uma etapa crítica, o ciclo de esterilização é validado por protocolos específicos que visam garantir a integridade da operação. A demanda de equipamentos com capacidades cada vez maiores e as implicações desse aumento na eficiência da esterilização tornaram importante uma análise mais detalhada dos resultados obtidos nos protocolos atuais. Este trabalho teve por objetivo avaliar os ciclos de esterilização de um tanque asséptico, baseado na distribuição de temperatura e pressão em seu interior, e a partir dos resultados, aumentar a compreensão dos fenômenos envolvidos na esterilização e quantificar sua eficiência. A análise das variáveis revelou que o ciclo de desaeração do tanque asséptico não foi completa, com retenção de ar representando de 13 a 23% do volume total do equipamento. Como consequência o processo de esterilização ocorreu em condição de não saturação de vapor. Esta situação altera o mecanismo de destruição térmica de microrganismos da condição úmida para não-úmida, na qual a resistência térmica dos esporos é mais elevada, levantando a questão da real eficiência dos processos e protocolos de esterilização atuais. .A aparente garantia da esterilidade comercial dos processos atuais pode ser explicada pelo uso de temperaturas e tempos excessivos. A revisão de procedimentos, protocolos e critérios de sucesso dos projetos existentes pode resultar em maior segurança quanto à eficiência de esterilização e redução de custos. Um novo protocolo de validação é proposto em refletindo os novos critérios de sucesso estabelecidos neste trabalho / Abstract: Aseptic tank systems are applied to production lines for shelf-stable, long-life products in order to store sterile product until aseptic filling, maintaining the commercial sterility condition achieved from previous production steps. To avoid microbial recontamination of the product, a sterility condition must be achieved in the aseptic tank system through the application of a heating, venting, and sterilization cycle. This cycle must be submitted to specific validation protocols to ensure operational integrity. The demand for larger capacity systems and the implication of this volume increase on sterilization efficiency require a more detailed review of the results obtained from current validation protocols. The purpose of this work was to evaluate an aseptic tank¿s sterilization cycles, through study of temperature distribution and internal pressure, in order to better understand key phenomena in aseptic tank sterilization and to quantify its efficiency. The analysis showed that the venting cycle was insufficient, with remaining air on the order of 13%-23% of the total tank volume. Consequently, the subsequent sterilization process was not conducted at the saturation point for steam. This different condition changes the kinetics for thermal destruction of microorganisms from a wet state to a dry state in which thermal resistance of spores is higher. This finding raises a question regarding the true efficacy of the sterilization process and validation protocols currently applied. The apparent success of current sterilization processes could be explained by the usage of excessive temperature and time. The review of procedures, protocols, and success criteria of current projects could result in greater assurance of sterilization efficacy and in cost reduction. A new validation protocol is proposed to reflect the new success criteria developed in this work / Mestrado / Tecnologia de Alimentos / Mestre em Tecnologia de Alimentos

Flow boiling in microchannels, while very promising as a cooling technology in electronics thermal management, is still a subject being explored that requires further investigation. Before applying this technology for high heat flux computer chip cooling, challenging issues such as fully understanding boiling mechanisms in confined spaces, extending and stabilising the nucleate boiling regime, suppressing flow boiling instabilities, maintaining uniform flow distribution among microchannels, have to be addressed. If flow boiling is to be used as a thermal management method for high heat flux electronics it is necessary to understand the behaviour of a non-uniform heat distribution, which is typically the case observed in a real operating computer chip. In this study, flow boiling of deionised water in a silicon microchannel heat sink under uniform and non-uniform heating has been investigated with particular attention to flow boiling instabilities. An experimental system was designed and constructed to carry out the experimental investigations. The experimental heat sink consisting of forty parallel rectangular microchannels with 194 μm hydraulic diameter together with integrated inlet and outlet manifold was fabricated on a silicon wafer using inductive coupled plasma dry etching, in conjunction with photolithographic techniques. A design with integrated temperature sensors made from a thin nickel film allows local temperature measurements with a much faster response time and smaller thermal resistance as compared to temperature measurements using thermocouples. The integrated heater was designed to enable either uniform or non-uniform heating (hotspot investigation) with a low thermal resistance between the heater and the channels. Numerical simulations for single phase flow in adiabatic conditions were used to assist the design of the manifold geometry in the microchannels heat sink. Microfabricated temperature sensors were used together with simultaneous high speed imaging in order to obtain a better insight related to temperature fluctuations caused by two-phase flow instabilities under uniform and non-uniform heating. Two types of two-phase instabilities with flow reversal were identified and classified into flow stability maps. The effect of inlet water temperature on flow boiling instabilities was experimentally studied, with the influence of different subcooling conditions on the magnitude of temperatures as well as the influence on temperature uniformity over the heat sink being assessed. The effect of various hotspot locations on flow boiling instabilities has been investigated, with hotspots located in different positions along the heat sink. Bubble growth and departure size have been experimentally investigated. The results of this study demonstrate that bubble growth in microchannels is different from that in macroscale channels. Furthermore, the effects of bubble dynamics on flow instabilities and heat transfer coefficient have been investigated and discussed.

Master´s thesis deals with desing of a heated bed for FDM 3D printer using the finite element method. It is briefly described the history of RepRap printers, construction and mechanical parts. Are discussed two methods of heating, heated by PCB boards and using power resistors. Furthermore is work closely focused on power resistors. There are presented methods and procedures which leads to an optimal distribution of heated components on the board of heated bed. In conclusion are presented results of testing which are compared with the simulations in ANSYS.

This work deals with the thermal load during cut-off grinding of high-strength bearing rings. Linear cut-off operations lead to a high rise in temperature over the cutting process. These leads, together with the limited material volume, in a heat build-up and the resulting grinding burn. The aim of this work was to prevent this head build-up by using two-axis cut-off operations. Therefore, known methods were theoretically considered and from this, alternative two-axis strategies were determined. For testing, experiments were carried out on a test set-up developed in this work. The tests showed that the two-axis strategies lead to significantly reduced temperatures, as well as non-grinding burn and partially burr-free cutting surfaces. However, the two-axis methods lead to increased process times, which is why approaches for their optimization have been discussed.

<p>The present environmental concerns and the rising human requirement for solutions with better comfort and lower costs have resulted in an increased awareness for the energy use in the built environment. Technical advances in building structural systems and materials, heating and other comfort-providing systems and controlling strategies all lead to the integration of building technology with the function of buildings and the aesthetics. Therefore, in the process of improving the performance of energy systems and increasing the energy efficiency, integrated system approaches are of high importance. Performing the necessary energy analysis before any construction-installation occurs can help designers and decision makers reach guided solutions. Hence, a broad range of calculation tools for evaluating the operation of energy systems and the controls in buildings have been developed the latest years with different levels of complexity and angles of focus.</p><p>However, research and development regarding holistic energy system designs and techniques are in their infancy. The standard tactic has been to isolate system parts, study them as stand-alone sub-systems and focus on optimising components or processes of a complex function. In the present study, it is demonstrated the necessity for uniting energy engineers, architects, installers and technicians regarding decision making upon the energy use for heating, ventilation and air-conditioning (HVAC) in the built environment. Systems approach has been employed for studying the research issue that is presented in the current thesis. An extended part of this treatise has been devoted to systems thinking in practice.</p><p>The thesis demonstrates systematic methods of modelling and analysing certain, integrated, domestic, HVAC applications. The reference system boundaries enclose the building as a construction and as a dynamic function, a comfort-providing system based on a heat pump, a low-temperature hydronic heat distribution system and controls in a residential application. Obviously, these are not the only components met in a hydronic heating system. Numerous pieces of equipment, as piping, circulating pumps, expansion tanks, zone valves, relief valves and other essential elements are needed to make a safe and functional heating system. However, this study focuses on the analysis of the chosen reference system. Several models have been developed in the computational tools of TRNSYS and EES. These tools have been employed because they allow co-solving, hence the integrated system as well as the interaction between the different parts of the system can be studied.</p><p>The foremost result of this study is that approaching the system as a whole provides a better picture of the operation of every system component and the interaction between them. Explanations are given for the parameters that have a significant impact on the system’s performance. The thesis shows the importance of factors that are not easy to predict, as well as the difference in the building’s behaviour under fast changing thermal loads when the incorporated thermal mass is altered. Finally, implementing sophisticated controls for reducing the energy costs without compromising thermal comfort is vital.</p>

The present environmental concerns and the rising human requirement for solutions with better comfort and lower costs have resulted in an increased awareness for the energy use in the built environment. Technical advances in building structural systems and materials, heating and other comfort-providing systems and controlling strategies all lead to the integration of building technology with the function of buildings and the aesthetics. Therefore, in the process of improving the performance of energy systems and increasing the energy efficiency, integrated system approaches are of high importance. Performing the necessary energy analysis before any construction-installation occurs can help designers and decision makers reach guided solutions. Hence, a broad range of calculation tools for evaluating the operation of energy systems and the controls in buildings have been developed the latest years with different levels of complexity and angles of focus. However, research and development regarding holistic energy system designs and techniques are in their infancy. The standard tactic has been to isolate system parts, study them as stand-alone sub-systems and focus on optimising components or processes of a complex function. In the present study, it is demonstrated the necessity for uniting energy engineers, architects, installers and technicians regarding decision making upon the energy use for heating, ventilation and air-conditioning (HVAC) in the built environment. Systems approach has been employed for studying the research issue that is presented in the current thesis. An extended part of this treatise has been devoted to systems thinking in practice. The thesis demonstrates systematic methods of modelling and analysing certain, integrated, domestic, HVAC applications. The reference system boundaries enclose the building as a construction and as a dynamic function, a comfort-providing system based on a heat pump, a low-temperature hydronic heat distribution system and controls in a residential application. Obviously, these are not the only components met in a hydronic heating system. Numerous pieces of equipment, as piping, circulating pumps, expansion tanks, zone valves, relief valves and other essential elements are needed to make a safe and functional heating system. However, this study focuses on the analysis of the chosen reference system. Several models have been developed in the computational tools of TRNSYS and EES. These tools have been employed because they allow co-solving, hence the integrated system as well as the interaction between the different parts of the system can be studied. The foremost result of this study is that approaching the system as a whole provides a better picture of the operation of every system component and the interaction between them. Explanations are given for the parameters that have a significant impact on the system’s performance. The thesis shows the importance of factors that are not easy to predict, as well as the difference in the building’s behaviour under fast changing thermal loads when the incorporated thermal mass is altered. Finally, implementing sophisticated controls for reducing the energy costs without compromising thermal comfort is vital. / QC 20101008

This thesis aims to implement dynamic load balancing mechanism into the parallel simulation model of the heat distribution in a CPU cooler. The first part introduces theoretical foundations for dynamic load balancing, describing current solution approaches. The second part refers to the heat distribution model and related topics such as MPI communications library or HDF library for data storage. Then it proceeds to the implementation of simulation model with dynamic 2D decomposition of square model domain. Custom geometry based dynamic load balancing algorithm was introduced, which works with this decomposition. Important part of the implementation is Zoltan library, used especially for data migration. At the end, a set of experiments was presented, which demonstrates load balancing abilities of designed model together with conclusions and motivation for future research.

Cette thèse a été dirigée par le Professeur Kauffmann de l’Université de Franche-Comté. Le co-directeur de l’Ecole Royale Militaire était le Docteur Johan Gallant et les essais à l’Institut franco-allemande de recherches de Saint-Louis (ISL) étaient encadrés par le Docteur Markus Schneider.Un lanceur à rails conventionnel est composé de deux rails conducteur connecté par un projectile. L’interaction entre le champ magnétique induit par le courant dans les rails et le courant dans le projectile résulte en une force électromagnétique accélérant. Dans cette thèse on utilise un projectile avec deux ponts de courant. Pour un lanceur à rails conventionnel la méthode la plus efficace pour augmenter la force sur le projectile est d’augmenter le courant dans les rails. Mais la densité de courant est limitée. L’échauffement des contacts entre les rails et les ponts de courant par l’effet Joule et la force de frottement, peut résulter dans la transformation d’un contact solide dans un contact plasma, ce qui est à éviter. Une possibilité d’adresser ce problème est d’ajouter des ponts de courant pour améliorer la distribution de courant. Une autre possibilité est d’appliquer un champ magnétique extérieur généré par un circuit extérieur qui nous permet d’augmenter la force électromagnétique sans augmenter le courant dans le circuit intérieur. Dans cette thèse l’objectif est d’étudier la distribution de courant et de température dans un projectile à deux ponts de courant pour un lanceur augmenté. Comme les deux ponts de courants et les rails du circuit intérieur forment un circuit fermé, le champ augmenté va induire un courant de circulation qui influence la distribution de courant entre les brosses. Le premier modèle de simulation est un modèle global du lanceur en PSpice qui nous permet de déterminer les courants globaux, la force électromagnétique, la position et la vitesse du projectile et la température moyenne des brosses. Le modèle global prend en compte l’effet de peau dû à la vitesse et est validé par des résultats expérimentaux. Le deuxième modèle est un modèle local en ANSYS, un code à éléments finis, pour un projectile fixe. Ce modèle permet une étude locale de la distribution de courant et de température. Un modèle pour la zone de contact entre les rails et la brosse est introduit. Le modèle local est utilisé pour calculer les coefficients de l’équation de force dans le modèle global. Les résultats des deux modèles de simulation sont cohérents.Le lanceur LARA, utilisé pour les essais, a une longueur de 1.5 m et un calibre de 15 mm. On disposait de trois bancs de condensateurs pour l’alimentation du lanceur en configuration non-augmenté et augmenté. Les vitesses à la bouche obtenues varient entre 48 et 214 m/s. Pour la détermination de la distribution de courant nous avons utilisé une méthode proposée par [SCH05a]. Cette méthode est une combinaison d’une mesure de tension entre deux pins dans les rails et dans une boucle. Nous avons constaté que les signaux obtenus avec cette méthode, appliquée dans ce régime de vitesse, sont perturbés par les courants de Foucault induits avant le projectile et les résultats ne répondent pas à nos attentes. Une méthode analytique basée sur la mesure de tension dans la boucle a été développée. Les résultats expérimentaux sont comparés avec les simulations. Nous avons constaté une bonne correspondance entre les valeurs des courants maximaux dans les rails calculés avec PSpice et les valeurs expérimentales, mais le courant calculé avec PSpice est plus faible dans la phase décroissante du courant. Les erreurs sur la vitesse sont inférieures à 10 %. Les deux modèles de simulation et les essais montrent que la brosse avant porte la plus grande partie du courant. La dernière partie de cette thèse est une étude paramétrique avec ANSYS pour l’avant-projet du circuit intérieur d’un lanceur à rail existant. / This thesis was supervised by Professor Jean-Marie Kauffmann of the University of Franche-Comté. The co-director at the Royal Military Academy was Dr. Johan Gallant and the experiments at Franch-German Research Institute ISL were directed by Dr. Markus Schneider. A conventional electromagnetic railgun is composed of two conducting rails connected by a projectile. The magnetic field generated by the current in the rails interacts in the projectile resulting in an electromagnetic force accelerating the projectile. The projectile used in this thesis is two brush projectile. For a conventional railgun the most efficient way to increase the force on the projectile is to increase the current in the rails. But the current density is limited. The heating of the sliding contacts between the brushes and the rails due to the Joule losses and the friction can cause the contacts and can result in contact transition which we want to avoid. One way to reduce the heating is to add more current brushes to obtain a better current distribution between the brushes. Another way is to add an extra pair of rails and create an additional magnetic field. This augmenting field allows us to increase the electromagnetic force without increasing the current through the projectile. In this thesis the current and heat distribution in a two brush projectile in a parallel augmented railgun is studied through simulations and experiments. Because the current brushes and the inner rails form a closed loop, the augmenting field will induce a loop current and influence the current distribution between the brushes. The first simulation model is a global model of the railgun in PSice which allows us to predict the global currents as well as the average temperature in the brushes, the force on the projectile and the position and the velocity of the projectile. The model takes into account the velocity skin effect and was validated based on experiments. The second model is a finite element model in ANSYS for a fixed projectile. This model allows a local study of the current and temperature distribution in the projectile. A model for the contact between the rails and the projectile is introduced. The local model is used to calculate the time-dependent coefficients for the force equation used in the global model. Both simulation models are compared and a good correspondence is found. The LARA railgun of ISL with a length of 1.5 m and a square caliber of 15 mm has been used for the experiments. A maximum of three capacitor banks was used for the non-augmented and the augmented configuration. The muzzle velocities obtained in the experiments vary between 48 and 214 m/s. To determine the current distribution between the brushes a technique proposed by [SCH05a] has been used. It is based on the measurement of the voltage between two pins in the rails in combination with the voltage in a loop. When applied to this velocity range, the eddy currents in front of the projectile hamper the interpretation of the signals and the results are not what we expected. An analytical method for the determination of the current distribution based on the voltage in the loop was introduced. The results are then compared with the results of the simulations. The maximum current in the rails found with PSpice shows a good correspondence with the experiments, the calculated decrease of the current is slightly overestimated. The errors on the velocities are less than 10%. Both simulation models and experiments show that the brush towards the breech carries the greater part of the current for the non-augmented as well as the augmented railgun. In the last part a parametric study is carried out with ANSYS for the preliminary design of an augmenting circuit for an existing railgun.

Darbo tikslas – naudojant kompiuterinį modeliavimą ištirti, kaip formuojasi temperatūriniai laukai didelėse erdvėse šalia šaltų įstiklintų paviršių, ir nustatyti, koks šildymo būdas labiausiai tinka mikroklimato parametrų užtikrinimui tokiose patalpose. Pasirinkus kompiuterinį programinį paketą SolidWorks ® Flow Simulation skirtingų aukščių patalpose sumodeliuotas ir išnagrinėtas temperatūrų pasiskirstymas prie įvairių įstiklintų paviršių, esant skirtingoms šildymo sistemoms. Darbe išanalizuoti 14 variantų patalpų, turinčių skirtingą įstiklinimo plotą, modeliai. Jose sumodeliuotos radiatorinio, grindinio ir orinio šildymo sistemos. Darbą sudaro įvadas ir problemos analizė, tikslo ir uždavinių jam pasiekti parinkimas, literatūros šaltinių apžvalga, tiriamų objektų analizė, modeliavimo programinų paketų apžvalga ir tinkamiausio programinio paketo pasirinkimas, modeliavimo rezultatų aptarimas ir išvados, informacijos šaltiniai, priedai. Nustatyta, kad geriausias šildymo būdas patalpoms su dideliais įstiklintais paviršiais yra radiatorinis. Darbo apimtis – 81 psl. teksto be priedų, 65 iliustr., 5 lent., 49 bibliografiniai šaltiniai, 2 priedai. / The assignment of this project is to investigate the forming of various temperature fields in large volumes next to cool glazed surfaces using digital modelling and determine the most efficient heating system solution for ensuring microclimate parameters in such accommodations. The heat distribution in various height spaces next to changing size glazed surfaces is modelled and analysed using SolidWorks ® Flow Simulation software package, comparing the results of several different heating systems. In this paper are analyzed 14 models of accommodations with changing size glazed surfaces, every with one or more of three: radiator, floor and air heating system. This paper consists of introduction, problem analysis, main objective and tasks to achieve it selection, source literature review, investigated objects analysis, modelling software packages review and a choice of the most suitable, simulations results interpretation and conclusion, references and appendixes. It was determined that most suitable heating system for indoor spaces with large glazed surfaces is radiator one. This paper consists of 81 pages of text, 65 pictures, 5 tables, 49 references, 2 appendixes.