Coagulation/flocculation/sedimentation is a common pretreatment process prior to microfiltration (MF) or ultrafiltration (UF) to alleviate membrane fouling, however there has been limited research on floatation as the pretreatment separation process. The main objective of this study is to compare sedimentation with floatation as part of the pretreatment for ultrafiltration of Ottawa River water (ORW) with relatively high natural organic matter (NOM) content. Water samples pretreated at two full-scale plants were subjected to multiple-day UF membrane fouling tests (constant flux with backwash and chemical cleaning) using an automated bench-scale UF hollow fiber membrane system. For all the experiments, the transmembrane pressure (TMP) increased sharply during the beginning of the operation (~10 h), which indicated the adsorption was significant. In the later cycles, the TMP showed a more linear constant increase, which indicated the built up of the cake layers. The total fouling index (TFI), hydraulically irreversible fouling index (HIFI) and chemical irreversible fouling index (CIFI) for floated water were much smaller than those of settled waters during both summer and winter testing. Thus, for this type of water coagulation/floatation pretreatment was superior process compared to coagulation/sedimentation, the decreased fouling appears to be linked to greater hydrophobic NOM removal by the coagulation/floatation. For all the tests, HIFI/TFIs were less than 0.1, which is to mean most of the fouling was reversible by hydraulic backwashing.Large fluctuation of backwash efficiencies with time were found for all the tested waters. Enhanced chemical backwash with 100 ppm chlorine and chemical clean with 0.1N NaOH & 200 ppm chlorine were found to be very effective at reducing fouling for pretreated ORW. As expected longer filtration cycles resulted in greater fouling but with a slightly greater degree of hydraulically reversible fouling.

Les micro-plasmas constituent une technologie d'avenir pour des applications aussi nombreuses que diverses : dépollution, traitement de surface, applications bio-médicales, accélération aérodynamique... Nous avons étudié ces micro-plasmas dans des gaz inertes (hélium ou argon), en les alimentant en courant continu dans des structures de type micro-cathode creuse. Afin de comprendre les mécanismes physiques régissant leur comportement, nous les avons caractérisés par plusieurs diagnostics, notamment par caméra ICCD et par spectrométrie d'émission optique. Ce dernier diagnostic nous a permis de déterminer la température du gaz des micro-plasmas, par l’analyse de la structure rovibrationnelle des raies du second système positif de l’azote (présent à l’état de traces), mais aussi d’effectuer des mesures de densité électronique, en analysant l’élargissement Stark de la raie H béta. Ces paramètres physiques obtenus expérimentalement, ont été comparés à leurs équivalents obtenus par simulation (logiciel GdSIM du laboratoire Laplace). Ce travail de thèse a également permis de montrer la possibilité d’atteindre le régime luminescent anormal d’un micro-plasma, en réduisant l’aire de la surface cathodique extérieure de la micro-cathode creuse. Ce régime de fonctionnement s’accompagne d’une hausse rapide de la température du gaz, ainsi que d’un phénomène d’hystérésis qui apparaît sur une courbe I-V, pour une rampe d’alimentation en courant linéairement croissante puis décroissante. Dans le cas de plusieurs micro-plasmas fonctionnant en parallèle, nous avons mis à jour un nouveau mécanisme, expliquant l’allumage des cavités de proche en proche. / The micro-plasmas are a promising technology for a lot of applications: environmental remediation, surface treatment, bio-medical applications, aerodynamic acceleration ... Our micro-plasmas are generated in microhollow cathode (M.H.C) structures, supplied by direct current and studied in rare gases (helium or argon). To understand the physical mechanisms ruling their behaviour, they have been characterized by several diagnostics, especially ICCD camera and optical emission spectroscopy. This last diagnostic has been used to determine the micro-plasma gas tempe rature , by analysing the bands 1.3 and 0.2 (from the second . positive system of nitrogen). but also to measure the electron density by analyzing the Stark broadening of the H beta line. We have also carried out simulations with a fully fluid model to obtain the spatial profiles of the electric field, the charge species densities and the gas temperature. Thus, we have studied the breakdown, the self-pulsing regime and the normal glow regime of our micro-plasmas. We have also demonstrated that a micro-plasma can work in the ab normal glow regime, at the condition to limit the cathode surface of the micro-device. For increasing values of curre nt. this abnormal glow regime is accompanied by a fast increase of the gas temperature. Moreove r, when the micro-plasma is supplied by a linear increasing-decreasing DC voltage ramp, this regime is accompanied by the formation of a hysteresis phenome non. At last, in the case of a micro-devi ce with severa 1micro-ho 1I0wcathodes in parallel, we exp lain how the cathode limitation favours the parallel ignition and is an alternative issue to the individual ballasting.

Orientador: Sergio Persio Ravagnani / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-07T19:00:28Z (GMT). No. of bitstreams: 1 Lavezo_AnaElisa_M.pdf: 1136570 bytes, checksum: e8e9754aa79e23bced02a8fa2d543e4c (MD5) Previous issue date: 2006 / Resumo: A separação de misturas gasosas é efetuada com o objetivo de obter um ou mais dos constituintes na forma altamente puros. Existem quatro métodos principais aplicados para a separação de gases: absorção, adsorção, destilação criogênia e membranas. A economia do processo determinará qual desses métodos é usado para alguma aplicação particular (Scott, 1995). A era moderna das membranas de separação de gases foi introduzída após 1980, quando as membranas poliméricas se tomaram economicamente viáveis (Robeson, 1999).Atualmente a separação baseada em membranas é utilizada largamente em escala industrial para produção de nitrogênio de alta pureza a partir do ar, tendo importante aplicação na inertização do ambiente para conservação de frutas e vegetais, reatores químicos e produção de NH3, assim como para segurança na operação com líquidos inflamáveis (Spillman, 1989). O objetivo deste trabalho é a otimização do custo total do processo de separação de misturas gasosas multicomponentes utilizando membrana de fibra oca. A otimização foi realizada utilizando o método "Constrained Rosenbrock (Hill AIgorithm)", para obter um produto final com alta qualidade e com um custo total minimizado. Para a otimização do custo total do processo são necessários os seguintes dados fornecidos pelo programa de Caramello (2002): pressão do permeado e da alimentação, taxa de fluxo do lado do alimentado, pureza e recuperação. A equação do custo total utilizada consiste em custo de instalação e custo operacional, ou seja, o custo total é o custo do módulo de permeação, custo de substituição da membrana (assumindo-se a vida útil da membrana a cada 3 anos), custo da energia elétrica e o custo de instalação do compressor.Otimizaram-se primeiramente dois parâmetros, número de cartuchos de membrana de fibra oca (QM) e pressão de alimentação (pt), em seguida fixou-se o número de cartuchos de membrana de fibra oca e foi otimizada a pressão de alimentação verificando se assim para cada análise o custo total otimizado para as seguintes purezas: 85%, 90%, 95% e 99% / Abstract: The separation of gas mixtures is made under the objective of obtaining one or more representatives in the highly pure form. Four methods can be used in gas separation: absorption, adsorption, distillation cryogenics and membranes. The economy of the process will determine which method will be used in a specific application (Scott, 1995). The modem era of gas-separation membrane was introduced in the early 1980s, when polymeric membranes became economically viable. (Robeson, 1999). Nowadays, membranes separation is used wide in industrial scale for the production of nitrogen in a high purity level from the air. This is an essential method for the inertization of the atmosphere air for fruits and vegetables storage, quimicos reactors and production of NH 3, as well as for safety when operating inflammable liquids (Spillman, 1989). The objective of this work is to optimization the cost related to the process of separation of multicomponents gas mixtures using membrane of hollow fiber. The optimization was made using "Constrained Rosenbrock (Hill Algorithm)", in order to obtain a high quality product with a reduced cost. For the process cost optimization the following data supplied for the program of Caramello (2002) is needed: feeding and permeated pressure, flow tax next to the feeder, purity and recovery. The equation of the cost used consists of: installation cost and operational cost. The total cost consists of the permeation module cost, the membrane substitution cost (assuming it useful life of the membrane to each 3 years), the electricity cost and finally the cost of the compressor installation. One first optimized two parameters: amount of membranes (QM) and pressure of feeding (P / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química

PART I Hollow-sphere (HS) steel foam is a relatively new material whose cellular morphology and material properties qualify it as a metallic foam. This is an innovative foam-like material that exhibits high stiffness paired with low relative densities. Technological advancements in the past few decades have enabled the manufacturing of this material by a sintering process and, as a result, research has begun to accelerate as a multi-school collaboration effort for this particular work. Even though commercialization has been a challenge for metallic foams, it is imperative that researchers continue to prove and promote the advantages of metallic foams despite the current challenges posed by commercialization. One of the most promising characteristics of metallic foams is their energy absorption capacity. This work explores hollow-sphere steel foam’s ability to absorb energy at high strain rates under a dynamic impact load and builds upon an earlier work of quasi-static compression loading. Since most research in this field has been attributed to aluminum open-cell foams, the objective of this work seeks to build upon and apply existing methods to cultivate new research material for hollow-sphere steel foam. The premise of this work began with experimental research analyzing stress-strain relationships of a mass impacting samples of HS steel foam with different kinetic energies. As a result, material properties were extracted and quantified such as elastic modulus, yield stress, and energy absorption, among others. These properties set the foundation for the next set of research; finite element analysis whose objective is to develop a functional material model that could be used for a later application in structural engineering, such as a blast or crash impact. PART II The second part of this thesis applies structural engineering mechanics to a complex arboricultural project. A particular American elm (Ulmus americana L.) tree is the focus of analysis due to its usage for tree climbing competitions. Structurally, this work is relevant to structural engineering by involving finite element analysis of a branch of this American elm tree. This particular work has the objective of understanding how a particular American elm branch behaves structurally under a variety of dynamic loads with different input parameters. Before any of the analyses can be implemented, the definite geometry of the tree has to be measured and material properties have to be calculated. Field experimental data are imperative for this project so that the idealized model can represent the real system as best as possible. Following the data acquisition and modeling of the tree, loads that were either measured or calculated are applied. These loads can be idealized as an impulse load and a cyclic load, with variability imposed within each of them. It is within this variability of the parameters within the loads that the purpose of this work arises. By applying extreme loads upon this tree branch, critical points along the branch can be identified by calculating maximum bending and axial stresses. These stresses indicate not only the critical points along the primary branch but in addition, they indicate the magnitude and severity of these potential stresses, which can be compared directly with the mechanical properties of the wood in the branch. The final intent of this work is to contribute to the knowledge of how a particular branch behaves dynamically in order to better equip tree climbers, academics, and professionals by integrating structural mechanics and arboriculture.

This doctoral thesis is focused on design of new equipment for aeration of water surface with low depth of water column. Aeration is one of ecological preventive methods to prevent growth of cyanobacteria. Increase of dissolved oxygen content in water mass leads to support of the growth of organisms which are disadvantaged by impossibility of movement in water mass and thus also to support biodiversity. Given biodiversity has a positive effect on water quality because it avoids the outbreak of one species of aquatic organism, in particular of cyanobacteria. Designed aeration equipment uses membrane formed by hollow fibre to transport oxygen into the water. When aeration dissolution of oxygen occurs directly on the membrane surface which prevents air leak in the form of bubbles. This type of aeration has low operating costs and high efficiency of input of the oxygen into the water. Distribution in the aquatic environment is ensured by special boat. This boat is moving on the water surface and the technology is installed on the upper deck. The aeration is carried out by an aeration module situated in the water. The movement of the boat is partially ensured by autonomous control.

Tato diplomová práce se zabývá výrobou ultratenkých keramických dutých vláken pomocí metody povlakování namáčením. Příprava keramických dutých vláken je v současnosti limitována rozměrem vnějšího a vnitřního průměru. Aplikace metody povlakování namáčením pro přípravu ultratenkých dutých je nový a technologicky náročný proces vyžadující volbu vhodné šablony a zároveň zvládnutí kontroly parametrů povlakování. Základními zvolenými materiály s vysokým aplikačním potenciálem jsou hydroxyapatit a oxid titaničitý. Samonosná dutá vlákna s tloušťkou stěny pod 1 m byla úspěšně připravena z obou materiálů. Dále byl také popsán proces povlakování namáčením obětovaných šablon. Tato metoda je unikátní, protože umožňuje produkci ultratenkých keramických dutých vláken s vnitřním průměrem pod 100 m a tloušťkou stěny pod 1 m.

This Master´s thesis describes the design and assessment of steel structure of a hangar located in Znojmo. The supporting structure of a hangar is 37,475 m span, 48 m lenght, clear hight at the highest point is 15,5 m. Main construction material is steel, grade S355J2. The supporting structure consist of a truss girders. The distance of each cross link sis 4 m. There is prepared statics calculation of the main load-bearing parts of the structure, including joints and details. The valid standards CSN EN were used in processing of this dissertation.

The thesis focuses on the polymer hollow fibres heat exchangers. The main object of the research is the formation and process of condensation on the outer surface of fibres and the effect of phase change on the heat transfer. The study deals with the influence of the geometry of the heat exchnager on the heat transfer and the condensation process. Fatigue tests of polymeric hollow fibres exchangers are also part of the work. The work provides an overview of the possible use of such heat exchangers in industrial applications associated with condensation.

The diploma thesis is devoted to the separation of a pollutant (NH3) from a water solution using an experimental technology device - membrane contactor. The theoretical part is mostly focused on the recent progress in the field of membrane contactors. The theoretical part also contains theory of absorption, chemisorption and microreactions, which is needed to understand the subject properly. The experimental part focuses on the construction of the experimental device and what does experimental device consist of. The efficiency of the device in transfer of ammonia to an nitrate salt of nitric acid solution was tested. At the end, experimental data are further discussed.

Disertační práce je zaměřena na kovové a polymerní výměníky tepla. Hlavním předmětem zkoumání je optimalizace teplosměnných ploch za účelem zvýšení účinnosti výměníku tepla. Tyto cíle byly dosaženy experimentálně a numericky pomocí modelování v ANSYS. Na základě dosažených výsledků byla rozpracována technologie křížového navíjení polymerních výměníků z dutých vláken. Experimentální zařízení původně určené pro navíjení tlakových nádrží bylo modifikované pro automatizovanou výrobu polymerních výměníků z dutých vláken, ježto může být použita při jejich masové výrobě. Tato práce se také zabývala výměníky tepla pro klimatizační systémy. Byly zkoumány možnosti využití polymerních výměníků z dutých vláken v těchto systémech. Mimo jiné byla provedena studie vlivu cyklického tepelného zatížení standardního kovového žebrovaného tepelného výměníku.