Doctor of Philosophy (PhD) / This thesis aims to establish a sound scientific methodology for the effective and efficient polishing of thermally stable PCD composites (consisting of diamond and SiC) for cutting tools applications. The surface roughness of industrial PCD cutting tools, 0.06 μm Ra is currently achieved by mechanical polishing which is time consuming and costly because it takes about three hours to polish a 12.7 mm diameter PCD surface. An alternative technique, dynamic friction polishing (DFP) which utilizes the thermo-chemical reactions between the PCD surfaces and a catalytic metal disk rotating at high peripheral speed has been comprehensively investigated for highly efficient abrasive-free polishing of PCD composites. A special polishing machine was designed and manufactured in-house to carry out the DFP of PCD composites efficiently and in a controllable manner according to the requirements of DFP. The PCD polishing process and material removal mechanism were comprehensively investigated by using a combination of the various characterization techniques: optical microscopy, SEM and EDX, AFM, XRD, Raman spectroscopy, TEM, STEM and EELS, etc. A theoretical model was developed to predict temperature rise at the interface of the polishing disk and PCD asperities. On-line temperature measurements were carried out to determine subsurface temperatures for a range of polishing conditions. A method was also developed to extrapolate these measured temperatures to the PCD surface, which were compared with the theoretical results. The material removal mechanism was further explored by theoretical study of the interface reactions under these polishing conditions, with particular emphasis on temperature, contact with catalytic metals and polishing environment. Based on the experimental results and theoretical analyses, the material removal mechanism of dynamic friction polishing can be described as follows: conversion of diamond into non-diamond carbon takes place due to the frictional heating and the interaction of diamond with catalyst metal disk; then a part of the transformed material is detached from the PCD surface as it is weakly bonded; another part of the non-diamond carbon oxidizes and escapes as CO or CO2 gas and the rest diffuses into the metal disk. Meanwhile, another component of PCD, SiC also chemically reacted and transformed to amorphous silicon oxide/carbide, which is then mechanically or chemically removed. Finally an attempt was made to optimise the polishing process by investigating the effect of polishing parameters on material removal rate, surface characteristics and cracking /fracture of PCD to achieve the surface roughness requirement. It was found that combining dynamic friction polishing and mechanical abrasive polishing, a very high polishing rate and good quality surface could be obtained. The final surface roughness could be reduced to 50 nm Ra for two types of PCD specimens considered from pre-polishing value of 0.7 or 1.5 μm Ra. The polishing time required was 18 minutes, a ten fold reduction compared with the mechanical abrasive polishing currently used in industry.

L'objectif de ce travail est d'étudier l'usinabilité des CMMp comme matériau de structure en substitution aux alliages réfractaires et de comprendre les mécanismes générateurs de poussière inhérents à leur usinage à sec. Les différents niveaux de chargement en céramique du CMM (5, 15, 25, 35 % de SiCp) ainsi que la variété d'outils PCD et des revêtements diamants nanostructurés étudiés, a permis d'évaluer dans un premier temps le choix structurel d'outillages en liaison avec la faisabilité industrielle de leur usage en usinage grande vitesse à sec d'un CMM Al/SiC. L'étude de faisabilité et la préconisation d'outillages ont été effectuées en prenant en compte des critères énergétiques et de qualité structurelle et environnementale. Les modes d'endommagement ainsi que les performances d'outils coupants ont été observés et analysés lors d'essais d'usure accélérée et de durabilité. La présence d'une usure adhésive suivie d'un mode abrasif de consommation d'interface accroit l'importance de la structure de l'outil (homogénéité, multiplicité des interfaces

Missions to Mars aim to characterize rock and subsurface soil samples and possibly bring some back to Earth for more thorough and sophisticated examination. The Martian surface is covered with basalt which has high compressive strength (andamp;gt;130 MPa), and is more difficult to drill than the much softer sedimentary formations that are presently being drilled using diamond core drills. The main objective of this thesis work is to provide the requisite groundwork towards the development of improved and sustainable drills for subsurface drilling applications on Mars, when their goals are obtaining samples. Since progressive drill-wear is substantial in sustained drilling, the experiments were designed and conducted to study the tool-wear mechanisms and understand the associated effects on drilling performance in subsurface drilling of basalt. Core drilling experiments are conducted with different drill geometries and cutting conditions in a Martian simulant, basaltic rock; monitoring thrust force, torque and measuring tool-wear for a series of successive depth-increments. Based on the experimental results an optimization model has been developed for maximizing drilling depth with minimum tool-wear. This preliminary work will help the development of smart and sustainable drills for dry drilling applications for future NASA missions to Mars.

Doctor of Philosophy (PhD) / This thesis aims to establish a sound scientific methodology for the effective and efficient polishing of thermally stable PCD composites (consisting of diamond and SiC) for cutting tools applications. The surface roughness of industrial PCD cutting tools, 0.06 μm Ra is currently achieved by mechanical polishing which is time consuming and costly because it takes about three hours to polish a 12.7 mm diameter PCD surface. An alternative technique, dynamic friction polishing (DFP) which utilizes the thermo-chemical reactions between the PCD surfaces and a catalytic metal disk rotating at high peripheral speed has been comprehensively investigated for highly efficient abrasive-free polishing of PCD composites. A special polishing machine was designed and manufactured in-house to carry out the DFP of PCD composites efficiently and in a controllable manner according to the requirements of DFP. The PCD polishing process and material removal mechanism were comprehensively investigated by using a combination of the various characterization techniques: optical microscopy, SEM and EDX, AFM, XRD, Raman spectroscopy, TEM, STEM and EELS, etc. A theoretical model was developed to predict temperature rise at the interface of the polishing disk and PCD asperities. On-line temperature measurements were carried out to determine subsurface temperatures for a range of polishing conditions. A method was also developed to extrapolate these measured temperatures to the PCD surface, which were compared with the theoretical results. The material removal mechanism was further explored by theoretical study of the interface reactions under these polishing conditions, with particular emphasis on temperature, contact with catalytic metals and polishing environment. Based on the experimental results and theoretical analyses, the material removal mechanism of dynamic friction polishing can be described as follows: conversion of diamond into non-diamond carbon takes place due to the frictional heating and the interaction of diamond with catalyst metal disk; then a part of the transformed material is detached from the PCD surface as it is weakly bonded; another part of the non-diamond carbon oxidizes and escapes as CO or CO2 gas and the rest diffuses into the metal disk. Meanwhile, another component of PCD, SiC also chemically reacted and transformed to amorphous silicon oxide/carbide, which is then mechanically or chemically removed. Finally an attempt was made to optimise the polishing process by investigating the effect of polishing parameters on material removal rate, surface characteristics and cracking /fracture of PCD to achieve the surface roughness requirement. It was found that combining dynamic friction polishing and mechanical abrasive polishing, a very high polishing rate and good quality surface could be obtained. The final surface roughness could be reduced to 50 nm Ra for two types of PCD specimens considered from pre-polishing value of 0.7 or 1.5 μm Ra. The polishing time required was 18 minutes, a ten fold reduction compared with the mechanical abrasive polishing currently used in industry.

Departamento Nacional de ProduÃÃo Mineral / Nos Ãltimos anos foi exponencial o avanÃo tecnolÃgico dos denominados VeÃculos AÃreos NÃo Tripulados (VANT) Estes equipamentos sÃo capazes de gerar produtos de sensoriamento remoto de elevada acurÃcia com baixo custo operacional desempenhando atividades antes executadas exclusivamente por aeronaves tripuladas Neste contexto o Departamento Nacional de ProduÃÃo Mineral (DNPM) para maximizar suas aÃÃes de fiscalizaÃÃo e gestÃo da mineraÃÃo firmou parceria com a Universidade de BrasÃlia (UnB) para desenvolvimento de um VANT de pequenas dimensÃes capaz de gerar ortomosaicos e Modelos Digitais do Terreno (MDT) de alta acurÃcia Para alcanÃar esse objetivo a UnB desenvolveu uma aeronave de 25 kg equipada com uma cÃmera nÃo mÃtrica capaz de obter fotografias de alta resoluÃÃo que apÃs processadas utilizando o mÃtodo de correlaÃÃo de imagens sobrepostas gera uma nuvem de pontos das coordenadas tridimensionais da superfÃcie permitindo a geraÃÃo de ortomosaicos e MDTs Contudo a tecnologia VANT ainda à considerada emergente SÃo comuns indagaÃÃes sobre o mÃtodo de levantamento o sensor utilizado e principalmente a acurÃcia dos resultados obtidos fato que motivou a elaboraÃÃo deste estudo de caso O objetivo principal desta pesquisa foi realizar a avaliaÃÃo da acurÃcia dos ortomosaicos e MDTs gerados a partir dos dados coletados pelo VANT desenvolvido pela UnB bem como sua aplicaÃÃo no cÃlculo do volume de pilhas de rejeito do calcÃrio sedimentar laminado da Bacia do Araripe no Cearà comercializado com o nome de Pedra Cariri sendo comparada sua acurÃcia com as obtidas pelas tecnologias Global Navigation Satellite System (GNSS) e Light Detecting and Ranging (LIDAR) mais utilizadas pelo seguimento da mineraÃÃo para esta finalidade Para avaliaÃÃo da acurÃcia foi usado o mÃtodo de testes de hipÃteses a partir da anÃlise de tendÃncia e precisÃo sendo os resultados classificados de acordo com o PadrÃo de ExatidÃo CartogrÃfica dos Produtos CartogrÃficos Digitais (PEC-PCD) ApÃs os experimentos realizados foi possÃvel constatar que o VANT-UnB/DNPM à capaz de gerar ortomosaicos e MDTs de alta acurÃcia compatÃveis com os obtidos por aerofotogrametria convencional desde que devidamente orientado por pontos de apoio de solo apresentando melhor acurÃcia no cÃlculo de volume neste estudo de caso se comparado com a modelagem realizada com as tecnologias GNSS e LIDAR / Recently, the technological advancement of Unmanned Aerial Vehicles (UAVs) has been exponential. This equipment are capable of generating remote sensing products of high accuracy at low operating costs, carrying out activities previously performed exclusively by manned aircraft. In this context, the National Department of Mineral Production (DNPM), aiming to maximize their actions of oversight and management of mining, has partnered with the University of Brasilia (UnB) for the development of a small UAV capable of generating orthomosaics and Terrain Digital models (TDM) with high accuracy. To achieve such objective, UnB has developed a 2,5 kg aircraft equipped with a small-format camera, nonmetric, capable of obtaining high-resolution photographs, after being processed through method of computing similarities between overlapping images, generates a cloud of points of the three-dimensional coordinates (x, y, z) of the surface, allowing to generate orthomosaics and TDMs. However, UAV technology is still considered emerging, being common questions about the survey method, used sensor and mainly accuracy of obtained results, a fact that motivated the elaboration in this case study. The main purpose this research is to evaluate of the accuracy of orthomosaics and TDMs generated from the data collected by the UAV developed by UnB, as well it's application in calculating the volume of laminate sedimentary limestone tailings piles of Araripe Basin in CearÃ, extracted in the form of tiles in natura marked under the name of Cariri Stone, compared it's accuracy with the results obtained with Global Navigation Satellite System (GNSS) and Light Detecting and Ranging (LIDAR) technologies, more commonly used by mining for this purpose. To evaluating the accuracy was used hypothesis testing method, from the trend and precision of analysis, and the results classified according to the Standard Cartographic Accuracy of Digital Cartographic Products (PEC-PCD). After the experiments performed, it was possible to acknowledge that the UAVUnB/DNPM is capable of generating with accuracy orthomosaics and MDTs, consistent with those obtained by conventional aerial photography, if properly oriented by ground control points. In this case study, the UAV showed better results when compared with modeling performed through GNSS and LIDAR technologies.

Aluminium applications in automotive will increase by 25 % over the next decade, mainly driven by the electrification and the reduction of fuel consumption. This diploma work aims to increase the understanding of the chemical interactions between aluminium alloys and typical tool systems in metal cutting. First the temperature at the tool-chip interface was estimated by FEM simulations, using the software AdvantEdge. Thereafter the chemical interaction of the tool-chip interface was calculated at the simulated temperature using the Thermo-Calc software. The thermodynamic data and descriptions of the multicomponent systems used where found in the literature, assessed by other authors, but critically reviewed for the use in this work. The results of the FEM simulations indicate that the temperature for machining aluminium with PCD and cemented carbide is between 60-80 % of the melting temperature of Al7wt %Si alloy. The calculations of the chemical interaction in turn results in that several hard precipitates can stick to or transform on the surface of the workpiece or tool-chip interface, for example SiC, Al4C3 and evidently diamond from the tool. This work concluded that more predictive modelling is needed to refine the results and the results from this work needs to be confirmed with experiments. The results show that the modelling can predict the reaction phases at the tool-chip interface, this can be used as input for the tool wear mechanisms during development of tooling solutions. / Aluminium användningen inom fordonsindustrin förväntas öka med 25 % under det närmsta decenniet, främst på grund av elektrifiering men också för att för att minska bränsleförbrukning. Målet med detta examensarbete är till att öka förståelsen för de kemiska interaktionerna mellan aluminiumlegeringar och typiska verktygssystem vid metallskärning, framförallt vid bearbetning av aluminiumlegeringar innehållande kisel med ett TiN-belagt PCD-verktyg och icke-belagda verktyg. Detta gjordes genom prediktiva FEM-simuleringar av temperatur, med hjälp av mjukvaran AdvantEdge. Parallellt med detta skapades databaser för simulering av den kemiska interaktionen mellan skär och bearbetningsmaterial i programvaran Thermo-Calc. De termodynamiska data och beskrivningarna av de termodynamiska system som används var bedömda av andra författare men kritiskt granskade för användning i detta arbete. Resultaten av FEM-simuleringarna gav den beräknade temperaturen för bearbetning av aluminium med PCD ligger någonstans mellan 60-80 % av smälttemperaturen för Al7wt % Si-legering. Beräkningarna av den kemiska interaktionen resulterar i sin tur i att flera hårda utskiljningar kan fastna på eller transformera på ytan mellan arbetsstycket och verktyget, till exempel SiC, Al4C3och diamant från verktyget. Resultaten från detta arbete visar att det går att förutsäga fasomvandlingar mellan skär och arbetsstycket, samt att detta kan användas som indata för skärförslitning under utvecklingen av verktygslösningar.

Abstract____________________________________________________________________ 2 ABSTRACT: Zea mays is generally considered to be a plant with inducible lysigenous aerenchyma formation. The degradation of some cortical cells is triggered by environmental conditions, usually in the form of stress (submergence etc.). These cells die in a process that shows signs characteristic for programmed cell death, such as nuclear DNA fragmentation or apoptotic ultrastructural alterations. Aerenchyma formed in primary roots of thirteen examined maize accessions, irrespective of cultivation conditions. The aerenchyma fraction correlated with the root length, not with its age. The dependence of aerenchyma formation on the presence of this phytohormone was proved by using an inhibitor of ethylene synthesis (AOA). It was found out that the aerenchyma formation depended on light conditions and that the lysigenous intercellulars intercellular spaces colocalized with areas with cells with characteristically fragmented nuclear DNA (TUNEL-positive nuclei). In experiments using the TUNEL reaction it was necessary to determine new dilution of the enzymatic mixture for the examined plant material. Only the observation of surface planes of free-hand root sections was considered relevant in both TUNEL-TMR and TUNEL-AP assays. TUNEL-AP...

Background: Cough is extremely common in childhood and a tool to objectively measure cough frequency would be clinically beneficial. To date paediatric cough monitoring systems have relied on manual cough counting which is time consuming and costly. The VitaloJAK™ (Vitalograph, UK) is a custom built 24hr semi-automated cough monitoring device that has been used successfully to quantify cough in adults. This thesis consists of a series of studies using the VitaloJAK™ monitor system in children. Methods: Firstly, we tested the feasibility of using the VitaloJAK™ for 24 hr cough recordings in children and tested existing compression software for cough quantification. The VitaloJAK™ system was then used to to assess and compare the cough frequency, variation and circadian distribution of cough in children with asthma, CF, and PCD during stable periods of disease and during an exacerbation. Finally, we used modelling to assess whether cough events are random events, or are clustered in time; the time intervals between coughs for each patient were calculated and fitted to an exponential model of random recurrences and a Weibull model for clustered recurrences. Results: The majority of children were able to wear the monitor for almost 24 hours without too much difficulty; overall, children wore the monitor for a median of 22.25 hours (0.38 – 24hrs). Using the compression software, a median of 100% (91-100) of coughs was retained and 24-hour records were reduced down to around 10% of their original size. There was no significant difference in cough frequency between the three disease groups. The median (range) cough frequency per hour was 3 (0.2 to 18) coughs/hour (c/h), 4 (0.5 to 37) c/h, and 4 (0.5 to 27) c/h for asthma, CF, and PCD groups respectively (p=0.3). Cough frequency in children was significantly greater during the day and reduced during sleep in all disease groups. There was a significant difference in the 24-hour cough frequency between the exacerbation and stable asthma group (median 11 (0-27) vs. 3 (0-5), p=0.004). The 24-hour pattern revealed a substantial variability in peak timing of cough in each respiratory disease. Children with asthma peaked in the early evening, those with CF in the morning, and those with PCD in the afternoon. No difference was found in the circadian cough rate, when divided into 6 4-hour time periods, either between the three diseases (p=0.18) or between stable and exacerbation phases among the asthmatic children (p=0.14). A significant difference was seen in the 24-hour total cough frequency between asthmatic children (median 4c/h; range 1-18) and adults (median 1 c/h; range 0.3-16); p=0.001. The temporal pattern of recurrence of cough events is non-randomly distributed over time, and this was best described by the Weibull model in the majority of the 24hr cough, day-time cough and night-time cough recordings in children and adults. The cough events appear to cluster together in time, with the probability of a second cough being initially high and decreasing with time. Conclusion: This thesis has demonstrated that the VitaloJAK™ semi-automated cough monitor provides an accurate estimate of cough frequency in children (sensitivity 100%) while significantly reducing the time required for analysis. A substantial variability in the timing of peak cough frequency exists in each respiratory disease and this might reflect different mechanisms of cough in each disease. Sleep appears to significantly reduce cough in all the diseases studied, both when disease is stable and exacerbating. In both asthmatic children and adults, the recurrence pattern of coughs is clustered and can be described by a Weibull distribution. This work has set a foundation for further investigation of the cough frequency and 24 hour cough circadian patterns in children.

Proteases play key roles in plants, maintaining strict protein quality control and degrading specific sets of proteins in response to diverse environmental and developmental stimuli. Similarities and differences between the proteases expressed in different species may give valuable insights into their physiological roles and evolution. Systematic comparative analysis of the available sequenced genomes of two model organisms led to the identification of an increasing number of protease genes, giving insights about protein sequences that are conserved in the different species, and thus are likely to have common functions in them and the acquisition of new genes, elucidate issues concerning non-functionalization, neofunctionalization and subfunctionalization. The involvement of proteases in senescence and PCD was investigated. While PCD in woody tissues shows the importance of vacuole proteases in the process, the senescence in leaves demonstrate to be a slower and more ordered mechanism starting in the chloroplast where the proteases there localized become important. The light-harvesting complex of Photosystem II is very susceptible to protease attack during leaf senescence. We were able to show that a metallo-protease belonging to the FtsH family is involved on the process in vitro. Arabidopsis knockout mutants confirmed the function of FtsH6 in vivo.

SILVA, Cristiano Alves da. Avaliação da acurácia dos ortomosaicos e modelos digitais do terreno gerados por VANT e sua aplicação no cálculo de volume de pilhas de rejeito da Pedra Cariri. 2015. 146 f. Dissertação (Mestrado em Geologia)-Universidade Federal do Ceará, Fortaleza, 2015. / Submitted by Vitor Campos (vitband@gmail.com) on 2016-10-05T23:02:45Z No. of bitstreams: 1 2015_dis_casilva.pdf: 5268107 bytes, checksum: c3a0b833ecc7a09a72b7062054e67836 (MD5) / Approved for entry into archive by Jairo Viana (jairo@ufc.br) on 2016-10-06T20:47:38Z (GMT) No. of bitstreams: 1 2015_dis_casilva.pdf: 5268107 bytes, checksum: c3a0b833ecc7a09a72b7062054e67836 (MD5) / Made available in DSpace on 2016-10-06T20:47:38Z (GMT). No. of bitstreams: 1 2015_dis_casilva.pdf: 5268107 bytes, checksum: c3a0b833ecc7a09a72b7062054e67836 (MD5) Previous issue date: 2015 / Recently, the technological advancement of Unmanned Aerial Vehicles (UAVs) has been exponential. This equipment are capable of generating remote sensing products of high accuracy at low operating costs, carrying out activities previously performed exclusively by manned aircraft. In this context, the National Department of Mineral Production (DNPM), aiming to maximize their actions of oversight and management of mining, has partnered with the University of Brasilia (UnB) for the development of a small UAV capable of generating orthomosaics and Terrain Digital models (TDM) with high accuracy. To achieve such objective, UnB has developed a 2,5 kg aircraft equipped with a small-format camera, nonmetric, capable of obtaining high-resolution photographs, after being processed through method of computing similarities between overlapping images, generates a cloud of points of the three-dimensional coordinates (x, y, z) of the surface, allowing to generate orthomosaics and TDMs. However, UAV technology is still considered emerging, being common questions about the survey method, used sensor and mainly accuracy of obtained results, a fact that motivated the elaboration in this case study. The main purpose this research is to evaluate of the accuracy of orthomosaics and TDMs generated from the data collected by the UAV developed by UnB, as well it's application in calculating the volume of laminate sedimentary limestone tailings piles of Araripe Basin in Ceará, extracted in the form of tiles in natura marked under the name of Cariri Stone, compared it's accuracy with the results obtained with Global Navigation Satellite System (GNSS) and Light Detecting and Ranging (LIDAR) technologies, more commonly used by mining for this purpose. To evaluating the accuracy was used hypothesis testing method, from the trend and precision of analysis, and the results classified according to the Standard Cartographic Accuracy of Digital Cartographic Products (PEC-PCD). After the experiments performed, it was possible to acknowledge that the UAVUnB/DNPM is capable of generating with accuracy orthomosaics and MDTs, consistent with those obtained by conventional aerial photography, if properly oriented by ground control points. In this case study, the UAV showed better results when compared with modeling performed through GNSS and LIDAR technologies. / Nos últimos anos foi exponencial o avanço tecnológico dos denominados Veículos Aéreos Não Tripulados (VANT) Estes equipamentos são capazes de gerar produtos de sensoriamento remoto de elevada acurácia com baixo custo operacional desempenhando atividades antes executadas exclusivamente por aeronaves tripuladas Neste contexto o Departamento Nacional de Produção Mineral (DNPM) para maximizar suas ações de fiscalização e gestão da mineração firmou parceria com a Universidade de Brasília (UnB) para desenvolvimento de um VANT de pequenas dimensões capaz de gerar ortomosaicos e Modelos Digitais do Terreno (MDT) de alta acurácia Para alcançar esse objetivo a UnB desenvolveu uma aeronave de 25 kg equipada com uma câmera não métrica capaz de obter fotografias de alta resolução que após processadas utilizando o método de correlação de imagens sobrepostas gera uma nuvem de pontos das coordenadas tridimensionais da superfície permitindo a geração de ortomosaicos e MDTs Contudo a tecnologia VANT ainda é considerada emergente São comuns indagações sobre o método de levantamento o sensor utilizado e principalmente a acurácia dos resultados obtidos fato que motivou a elaboração deste estudo de caso O objetivo principal desta pesquisa foi realizar a avaliação da acurácia dos ortomosaicos e MDTs gerados a partir dos dados coletados pelo VANT desenvolvido pela UnB bem como sua aplicação no cálculo do volume de pilhas de rejeito do calcário sedimentar laminado da Bacia do Araripe no Ceará comercializado com o nome de Pedra Cariri sendo comparada sua acurácia com as obtidas pelas tecnologias Global Navigation Satellite System (GNSS) e Light Detecting and Ranging (LIDAR) mais utilizadas pelo seguimento da mineração para esta finalidade Para avaliação da acurácia foi usado o método de testes de hipóteses a partir da análise de tendência e precisão sendo os resultados classificados de acordo com o Padrão de Exatidão Cartográfica dos Produtos Cartográficos Digitais (PEC-PCD) Após os experimentos realizados foi possível constatar que o VANT-UnB/DNPM é capaz de gerar ortomosaicos e MDTs de alta acurácia compatíveis com os obtidos por aerofotogrametria convencional desde que devidamente orientado por pontos de apoio de solo apresentando melhor acurácia no cálculo de volume neste estudo de caso se comparado com a modelagem realizada com as tecnologias GNSS e LIDAR.