Lake Waikare is a large, shallow eutrophic lake devoid of submerged macrophytes. I investigated potential methods for re-establishing submerged macrophytes in the lake. Specifically, I subjected charophyte (Chara corallina) plantlets to two treatments of exposure in the lake (in areas exposed and sheltered from wind) to test for survival and growth under these conditions, and inside and outside fish exclosures to test for growth and survival in the presence of fish. While plantlets grew outside the exclosures in winter, their accumulated biomass over 21 days was less than protected plantlets. In winter, the accumulated biomass was lower outside than inside exclosures (by ~40%) at the sheltered site and was lower outside than inside exclosures (by 43%) at the exposed site. Overall, growth rates in winter were higher at the sheltered site (compared to the exposed site) by ~7%. In summer, charophyte accumulated biomass inside the exclosures increased by 85%, while at the sheltered site accumulated biomass increased by 58%. Outside the exclosures in summer the plantlets were completely removed at both sites. Overall, growth rates where higher at the exposed site than the sheltered site by 31%. Fish were responsible for the partial removal of plantlets in winter and total removal of plantlets in summer, and therefore affect the survival and growth of charophytes in Lake Waikare. The embayment at the sheltered site provides the best location in winter for re-establishment of charophytes from oospores because better growth rates were obtained there, and its sheltered location provides protection from severe wave action found at the exposed site. Oospores did not germinate after being submersed in the lake for 90 days due to heavy sedimentation. To induce an improvement in the present light climate, Alum was tested to determine its effectiveness and longevity for settling lake sediments to allow charophytes to establish and grow. Examining the settling rates of Lake Waikare sediments and water treated with Alum over a range of suspended sediment concentrations and time intervals, sediments settled faster with Alum than without for at least 15 days (at 200 g l^1 suspended sediment concentration) and it remained active to 60 days but at reduced effectiveness. At the other concentrations tested (100 g l^1 and 300 g l^1 suspended sediment concentration), Alum responses were insignificant. An improved light climate achieved by fish removal or Alum treatment will likely not be sufficient to permit the re-establishment of submerged macrophytes due to the turbid, algal-dominated state of the lake. The present nutrient and sediment levels, wave climate and fish influence must be mitigated so charophyte plantlets can be established.

No description available.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1959. / Includes bibliographical references (p. 92-95).

Filtration is an important process in drinking water treatment to ensure the adequate removal of particle-bound pathogens (i.e. Giardia and Cryptosporidium). Filtration performance is typically monitored in terms of filtered water turbidity. However, particle counts may provide further insight into treatment efficiency, as they have a greater sensitivity for detecting small changes in filtration operation. To optimize the filtration process at the Elgin Area WTP in terms of post-filtration particle counts, artificial neural network (ANN) models were applied. Process models were successfully developed to predict settled water turbidity and particle counts. Additionally, two inverse process models were developed to predict the optimal coagulant dosage required to attain target particle counts. Upon testing each model, a high correlation was observed between the actual and predicted data sets. The ANNs were then integrated into an optimization application to allow for the transfer of real-time data between the models and the SCADA system.

Filtration is an important process in drinking water treatment to ensure the adequate removal of particle-bound pathogens (i.e. Giardia and Cryptosporidium). Filtration performance is typically monitored in terms of filtered water turbidity. However, particle counts may provide further insight into treatment efficiency, as they have a greater sensitivity for detecting small changes in filtration operation. To optimize the filtration process at the Elgin Area WTP in terms of post-filtration particle counts, artificial neural network (ANN) models were applied. Process models were successfully developed to predict settled water turbidity and particle counts. Additionally, two inverse process models were developed to predict the optimal coagulant dosage required to attain target particle counts. Upon testing each model, a high correlation was observed between the actual and predicted data sets. The ANNs were then integrated into an optimization application to allow for the transfer of real-time data between the models and the SCADA system.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-08-26T23:06:54Z No. of bitstreams: 1 FelipeFernandesCavalcante_DISSERT.pdf: 15830059 bytes, checksum: 1df43f246bc497f6fb2c86ad9f43fb04 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-08-30T22:45:53Z (GMT) No. of bitstreams: 1 FelipeFernandesCavalcante_DISSERT.pdf: 15830059 bytes, checksum: 1df43f246bc497f6fb2c86ad9f43fb04 (MD5) / Made available in DSpace on 2016-08-30T22:45:53Z (GMT). No. of bitstreams: 1 FelipeFernandesCavalcante_DISSERT.pdf: 15830059 bytes, checksum: 1df43f246bc497f6fb2c86ad9f43fb04 (MD5) Previous issue date: 2016-05-06 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Sabe-se que a grande parte das ligas de alum?nio pode sofrer varia??es significativas em suas propriedades mec?nicas dependendo do tratamento de envelhecimento realizado. Por?m, poucos trabalhos apontam as caracter?sticas dessas ligas em condi??es subenvelhecidas e superenvelhecidas, principalmente em rela??o ? tenacidade ? fratura. Al?m disso, estudos recentes apontam que algumas ligas de alum?nio subenvelhecidas podem sofrer uma esp?cie de auto cura, ou seja, esses materiais podem, quando solicitados devido a algum esfor?o externo, tender a um fechamento de algum defeito como uma trinca devido ? precipita??o din?mica, o que aumentaria sua capacidade de resistir ?s solicita??es. Neste contexto, neste trabalho ? avaliada a rela??o entre a tenacidade ? fratura e a resist?ncia ? tra??o e as condi??es de tratamentos t?rmicos de duas ligas de alum?nio (2024-T351 e 7075-T651), tanto na condi??o de entrega quanto submetidas a tratamentos t?rmicos de solubiliza??o (a 480 0C por 2,5 h) e envelhecimento artificial (145 0C por 8, 10, 16 e 24 h para a 7075, e 190 0C por 1, 3, 5, 8 e 12 h para a 2024), portanto, em condi??es de subenvelhecimento (abaixo do m?ximo de dureza), envelhecida (no ponto de m?xima dureza) e superenvelhecimento (al?m do ponto de m?xima dureza). Os materiais, nestas diferentes condi??es de processamento foram caracterizados do ponto de vista mec?nico - atrav?s dos ensaios de tenacidade ? fratura, utilizando a metodologia de entalhe chevron - KICVM (ASTM 1304), de tra??o uniaxial (ASTM E8M) e dureza HRB (ASTM E18) - e do ponto de vista estrutural, atrav?s da microscopia ?ptica, MEV e EDS. As microestruturas obtidas nas diferentes condi??es s?o avaliadas por MEV e DR-X. Os micromecanismos de fratura das amostras de tra??o e tenacidade ? fratura s?o avaliados por MEV. Em rela??o ? dureza verificou-se, para ambas as ligas, que ouve apenas um pequena tend?ncia de redu??o dos valores obtidos para a amostras envelhecidas em rela??o ao estado de entrega. Os resultados dos ensaios de tra??o indicam tamb?m uma pequena redu??o da resist?ncia das amostras envelhecidas, em rela??o ao estado de entrega. Estes resultados de dureza e tra??o indicam que a m?xima resist?ncia pode ser obtida para tratamentos de envelhecimento por 5 h (2024) e entre 10 e 12 h (7075). Os resultados de tenacidade ? fratura mostram que n?o houve influ?ncia significativa dos tempos de envelhecimento de 8h, 10h, 16h e 24h sobre os valores de KICV para a liga 7075, apesar dos tratamentos de envelhecimento terem aumentado a tenacidade ? fratura em rela??o ao estado de entrega. Em rela??o ? liga 2024, nem todos os resultados de tenacidade ? fratura puderam ser validados em fun??o da trajet?ria de crescimento de trinca fora do regime de abertura (modo I), mesmo para corpos de prova de maiores dimens?es. Este resultado indica que os diferentes tratamentos de envelhecimento da liga 2024 atuaram no sentido de aumentar a tenacidade do material, elevando a amplitude dos eventos inel?sticos ? frente da trinca. / Heat treatable aluminum alloys may experience significant changes in mechanical properties depending on heat treatment developed. Futhermore, a few works discuss about this properties in underaged and overaged conditions, mainly about fracture toughness. Recently, some researches showed that some aluminum alloys in underaged conditions may indicate the self healing phenomenon, in other words, when streched mechanically, the material could present a closure, or a reduction in crack growth ratio due local compressive stress associated to dynamic precipitation. In this context, its valued the relationship between fracture toughness, mechanical properties and heat treatment in two aluminum alloys (2024-T351 e 7075-T651) when submitted to solubilization (480 ?C for 2,5h) and artificial aging (145 ?C for 8h, 10h, 12h, 16h and 24h for 2024-S1 named first set and 7075; and 190 ?C for 1h, 3h, 5h, 8h and 12h for 2024-S2, second set), obtaining underaged, peak hardness and overaged conditions. The samples were featured using fracture toughness tests with a chevron notch, K??? (ASTM E1304); tensile tests (ASTM E8/E8M) and Vickers hardness (ASTM E 384). In structural aspects, this alloys were featured using optical microscopy and scanning electron microscopy (SEM), in microstructural aspects, using energy-dispersive X-ray spectroscopy (EDS). The micromechanisms of fracture surface on chevron samples are showed using SEM. After results, hardness and ultimate tensile stress showed maximum values between 3h and 5h (2024-S2) and approximately 10h and 12h (7075). About 2024-S2 alloy, it is showed the phenomenon of dynamic precipitation in delivery state, underaged and peak aged samples, due little peaks on stress-strain curves. However, in 2024 first and second sets, all results cannot be valid because the samples showed a significant change in fracture mode presenting a mix of mode I + mode II, futhermore, thickness B is not sufficient for attend ASTM E 1304. The 7075 aluminum alloy presented a distinguished behavior, showing independence in properties like fracture toughness and hadness mainly in overaged conditions, because as the hardness value increase in this condition, fracture toughness increased also. Besides that, K??? values showed no much variation besides the different times of aging, despite this values are much high than delivery state condition. About micromechanisms of fracture, all conditions presented dimples, and cleavage fracture associated to coarse precipitates.

Arbetets syfte är att undersöka svällande alunskiffer i Östersund, vad de senaste framstegen är för vad som orsakar svällning och hur den kan identifieras och hanteras. Enklare laborationsmoment utförs med provmaterial från jord-bergsondering i Östersund, men arbetet är främst en litteraturstudie. Alunskiffer har en varierande sammansättning av organiskt material, kalkrika mineraler och järnsulfider. Svällningen orsakas av oxidationen av järnsulfider vilket leder till bildning av gipskristaller. Omfattande krafter kan utvecklas i samband med svällningen vilket gör det till ett stort problem som kan orsaka deformationer av ovanliggande byggnader. Vårt förslag till hur svällskiffer kan identifieras är att utföra en övergripande kartläggning av alunskiffern i Östersund. Dess beskaffenhet bör undersökas kemiskt för att ta reda på halten svavelkis, magnetskis och andra mineral. Skifferns mekaniska egenskaper bör undersökas ytterligare. För att motverka svällningen föreslår vi att de metoder som tidigare prövats i Östersund och visat sig vara framgångsrika bör undersökas och utvecklas ytterligare. Inspiration kan också tas från gruvindustrin och hur de arbetar för att motverka surt avfall. De laborativa momenten visar att svällförloppet inte var tillräckligt snabbt för att ge ett resultat under testperioden på drygt två veckor. Smektittestet visar att det inte förekommer svällande lera, smektit, i borrkaxprovet från jord-bergsonderingen. / The purpose of the essay is to examine swelling alum shale in Östersund, what the state of the art concerning the cause of the swelling and how it may be identified and dealt with. Minor laboratory experiment is performed with test materials from soil-rock probing in Östersund, although the essay is mainly focused on studying literature. Alum shale has a varied composition of organic matter, calcareous minerals and iron sulphides. The swelling is caused by oxidation of the iron sulphides which forms gypsum. The extensive forces associated with the swelling can inflict deformations in the overlying buildings and is a major issue in Östersund. Our suggestions for how to identify the swelling shale is to make an extensive survey of the Östersund area. The survey would locate the alum shale and take samples to determine the chemical composition of the shale. We also suggest further analysis of the mechanical properties of the shale. Our suggestions for how to deal with the swelling would be to further examine the methods that proved to be successful at earlier attempts in Östersund. Inspiration can also be found in the mining industry and how they deal with acid mine drainage. The smectite test show that there is no swelling clay, also known as smectite, present in the drill cutting sample from the soil-rock probing. The swelling test show no signs of swelling caused by pyrite oxidation and the development of gypsum, during the test period of around two weeks.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-05-07T00:01:05Z No. of bitstreams: 1 PedroHenriqueSalesDaCosta_DISSERT.pdf: 3167327 bytes, checksum: e3758236165e8d3906f6f8f92e8a236b (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-05-09T20:11:14Z (GMT) No. of bitstreams: 1 PedroHenriqueSalesDaCosta_DISSERT.pdf: 3167327 bytes, checksum: e3758236165e8d3906f6f8f92e8a236b (MD5) / Made available in DSpace on 2016-05-09T20:11:14Z (GMT). No. of bitstreams: 1 PedroHenriqueSalesDaCosta_DISSERT.pdf: 3167327 bytes, checksum: e3758236165e8d3906f6f8f92e8a236b (MD5) Previous issue date: 2015-08-28 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Em muitos casos o passe de raiz ? uma etapa cr?tica da soldagem, uma vez que sua execu??o ? afetada por diversos fatores, tais como varia??o da abertura da junta, ?ngulo do chanfro, dimens?es da face (nariz) da raiz, inclina??o da tocha, velocidade de soldagem e velocidade de alimenta??o. Al?m disso, a escolha do processo de soldagem ? um fator primordial para garantir a execu??o de um passe de raiz com adequadas propriedades mec?nicas e metal?rgicas. Nesse contexto, este trabalho teve como objetivo estudar a viabilidade dos processos de soldagem MIG-P CC+ e TIG-A aplicado ao passe de raiz em chapas de 200 x 200 x 12,75 mm da liga de alum?nio AA 5052. Para tal, foram analisadas configura??es diferentes de soldagem: o tipo de chanfro (em V e em gola com L=2,00 e 3,00 mm) e dois tipos de metais de adi??o (ER 4043 e 5356). Como metodologia de compara??o, foi determinada a mesma corrente de 150 A e taxa de deposi??o do metal de adi??o Va/Vs = 14, foram realizadas 8 combina??es de par?metros, cada uma com 3 repeti??es, totalizando 24 testes, salientando que foi usada apenas a configura??o de chanfro mais adequada para o TIG-A. S?o apresentados resultados da micrografia e microdureza das zonas fundida e termicamente afetada e n?veis de dilui??o para as juntas soldadas com os distintos metais de adi??o, al?m da radiografia. Nas condi??es estabelecidas neste trabalho, pode-se afirmar que o processo TIG-A apresentou melhores resultados em rela??o ao MIG-P CC+. Em rela??o ? configura??o do chanfro, o que se mostrou mais adequado foi o chanfro em V, para ambos os metais de adi??o e processos. N?o ocorreram defeitos como falta de fus?o, mordeduras e rugosidades. Em rela??o aos n?veis de dilui??o, foram constatados maiores valores quando utilizado o processo MIG-P CC+ para o ER 4043, assim como o processo TIG-A na configura??o de chanfro em V. O metal de adi??o ER 4043 apresentou uma quantidade de poros maior em rela??o ao ER 5356, em ambos os processos. Foi observada ? presen?a de um refino de gr?o, al?m de maiores n?veis de dureza em todas as soldas realizadas com o metal de adi??o ER 5356. / In many cases the root pass is a critical step of welding, since its execution is affected by several factors, such as variation of joint opening, chamfer angle, dimensions of the face (nose) root, torch inclination, welding speed and feed speed. Moreover, the choice of the welding process is a key factor to ensure the execution of a root pass with adequate mechanical and metallurgical properties. In this context, this work aimed to study the feasibility of MIG-P CC+ and TIG-A welding processes applied to the root pass in plates of 200 x 200 x 12,75 mm of the AA 5052 aluminum alloy. For this, different configurations of welding were analyzed: chamfer type(V and collar with L=1,0 and 3,00 mm) and two types of addition metals (ER 4043 and 5356). As compared methodology, It was determined the same current 150 A and the deposition rate of addition metal Va/Vs = 14, they were proposed 12combinations of parameters, each with 3repetitions, totaling 36 tests, stressing that It was used only the most appropriate chamfer setting for TIG-A. Results of micrograph and microhardness of fusion and heat affected zones and dilution levels for welded joints with diferente addition metals, beyond radiography. At the established conditions in this work, it can be said that the TIG-A process showed better results in relation to MIG-P CC+. About the chamfer configuration, which was more appropriate was V chamfer, for both addition metals and process. There were no defects such as lack of fusion, bites and roughness. Relative to dilution levels, higher values were observed when used the MIG-P CC+ process for the ER 4043, as well as TIG-A in the V chamfer configuration. ER 4043 addition metal showed a larger amount of pores in relation to the ER 5356, in both process. It was observed the presence of a grain refining, beyond higher hardness levels in all welds made with the ER 5356 addition metal.

Made available in DSpace on 2014-12-17T15:14:52Z (GMT). No. of bitstreams: 1 EduardoMD_DISSERT.pdf: 1460594 bytes, checksum: 3bdc57732c952c77e8ca0b42292d1e86 (MD5) Previous issue date: 2011-01-27 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / In this work we deposit via non-reactive magnetron sputtering of radio-frequency nanofilmes of nitreto of aluminum(AlN). The nanofilms aluminum nitride are semiconductors materials with high thermal conductivity, high melting point, piezoelectricity and wide band gap (6, 2 eV) with hexagonal wurtzite crystal structure, belonging to the group of new materials called III-V nitrides in which together with the gallium nitride and indium nitride have attracted much interest because they have physical and chemical properties relevant to new technological applications, mainly in microelectronic and optoelectronic devices. Three groups were deposited with thicknesses nanofilms time dependent on two substrates (glass and silicon) at a temperature of 25 ? C. The nanofilms AlN were characterized using three techniques, X-ray diffraction, Raman spectroscopy and atomic force microscopy (AFM), examined the morphology of these. Through the analysis of X-rays get the thickness of each sample with its corresponding deposition rate. The analysis of X-rays also revealed that nanofilms are not crystalline, showing the amorphous character of the samples. The results obtained by the technique, atomic force microscopy (AFM) agree with those obtained using the technique of X-rays. Characterization by Raman spectroscopy revealed the existence of active modes characteristic of AlN in the samples / Neste trabalho depositamos via magnetron sputtering de r?dio-frequ?ncia n?o reativo nanofilmes de nitreto de alum?nio (AlN). Os nanofilmes de nitreto de alum?nio s?o materiais semicondutores com alta condutividade t?rmica, elevado ponto de fus?o, piezoeletricidade e largo "bandgap"(6;2 eV) com estrutura cristalina wurtz?tica hexagonal, pertencentes ao grupo de novos materiais denominados nitretos III-V que em conjunto com o nitreto de g?lio e o nitreto de ?ndio t?m despertado muito interesse por possu?rem propriedades f?sico-qu?micas relevantes para novas aplica??es tecnol?gicas, principalmente em microeletr?nica e dispositivos optoeletr?nicos. Foram depositados tr?s grupos de nanofilmes com as espessuras depend?ntes do tempo, sobre dois tipos de substratos (vidro e sil?cio) a uma temperatura de 25?C. Os nanofilmes de AlN foram caracterizados usando tr?s t?cnicas, a difra??o de raios-X, espectroscopia Raman e microscopia de for?a at?mica (AFM), analisado-se a morfologia desses. Atrav?s da an?lise dos raios-X obtemos a espessura de cada amostra com sua respectiva taxa de deposi??o. A an?lise dos raios-X tamb?m revelou que os nanofilmes n?o s?o cristalinos, evidenciando o car?ter amorfo das amostras. Os resultados obtidos atrav?s da t?cnica, microscopia de for?a at?mica (AFM) concordam com os obtidos usando a t?cnica de raios-X. A caracteriza??o por espectroscopia Raman evidenciou a exist?ncia de modos ativos caracter?sticos do AlN nas amostras analisadas

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-01-27T12:30:35Z No. of bitstreams: 1 EraldoCamaraDeSouza_TESE.pdf: 1960987 bytes, checksum: aaf762025bc316dd0b3bce3590afc7a7 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-01-30T14:17:00Z (GMT) No. of bitstreams: 1 EraldoCamaraDeSouza_TESE.pdf: 1960987 bytes, checksum: aaf762025bc316dd0b3bce3590afc7a7 (MD5) / Made available in DSpace on 2017-01-30T14:17:00Z (GMT). No. of bitstreams: 1 EraldoCamaraDeSouza_TESE.pdf: 1960987 bytes, checksum: aaf762025bc316dd0b3bce3590afc7a7 (MD5) Previous issue date: 2016-07-22 / Neste trabalho foram obtidos comp?sitos alumina - tungst?nio (Al2O3 ? W), a partir da rea??o aluminot?rmica dos p?s de paratungstato de am?nia (APT) e alum?nio, misturados e mo?dos em moinho de alta energia. O p? obtido na moagem foi inserido numa tocha de plasma, impulsionado por um jato de arg?nio, e ao interagir com o plasma, foi aquecido abruptamente at? a temperatura de igni??o do alum?nio, reagindo exot?rmicamente. O produto da rea??o foi depositado sobre um substrato met?lico confeccionado em lat?o. Foram analisadas a influ?ncia da varia??o do fluxo de igni??o/alimenta??o e das dist?ncias tocha - substrato. Alternativamente, foi acoplado ? tocha, um dispositivo de confinamento do jato de plasma para as dimens?es do substrato. Os comp?sitos foram caracterizados quanto ? composi??o, fases e distribui??o de fases. A caracteriza??o das fases foi obtida por difra??o de raios X, a an?lise morfol?gica, atrav?s de microscopia eletr?nica de varredura - MEV e a an?lise qu?mica, atrav?s de espectroscopia de energia dispersiva - EDS. Os comp?sitos obtidos com o fluxo de plasma confinado apresentaram maior percentual de redu??o em rela??o a quantidade de W obtido, principalmente, com o fluxo de alimenta??o/igni??o de 5,0 l/min e 40mm de dist?ncia tocha-substrato. / In this work composite alumina ? tungsten (Al2O3 ? W) was obtained from the aluminothermic reaction of ammonium paratungstate (APT) and aluminum powders, mixed and grounded in high-energy mill. So the powder obtained was inserted in a plasma torch feeder, driven by a flux of argon, and when interacted with the plasma, was abruptly heated to the aluminum ignition temperature, reacts exothermically. The product of this reaction was deposited on a brass substrate. The influence of variation ignition/powder feeding as well as the distance from torch until substrate were analysed. Alternatively a confinement device for the plasma jet was attached in order to adjust the substrate dimensions. Chemical composition, phases and phase distribution of these composite materials were characterized. The X ? ray diffraction was used to analyze the existent phases; the Scanning Electron Microscopy (SEM) was used to perform the morphological aspect of the powder; and finally the Energy Dispersive Spectroscopy (EDS) was used for analyzing the chemical composition. The composites obtained by using confined plasma flux showed greater percentage reduction from the amount of W mainly when the feed/injection flow of 5 l/min and 40 mm of distance away torch-substrate were set up.