This study was undertaken to develop an analytical model that is capable of predicting the torque requirements of a rotavator fitted with commercially available L-shaped blades. An analytical approach based on the limit equilibrium analysis was used to develop the proposed model. The proposed model was verified by comparing the model and measured torque requirements at predetermined rotavator blade angular positions from the horizontal for a down-cut rotavator. The study findings indicated that there was an optimum set tillage depth for each rotavator configuration and operational conditions at which the resultant horizontal thrust generated was greatest. This unique depth was influenced by the bite length. The validation of the proposed model showed that the predicted and measured torque requirements, at different angular blade positions from the horizontal, correlated reasonably well for all the set tillage depths. As the depth of tillage increased, however, the curve for the measured torque requirements exhibited a cyclic behaviour after the peak torque requirements value had been recorded. The cyclic behaviour was probably due to the re-tilling and the instability of the tool-frame carrier, which increased with the set tillage depth. The knowledge contributed by this research will afford the designers of active tillage tools a better understanding of the operations of the rotavator, particularly in deep tillage. The modelling approach, and instrumentation technique used in this research, can be extended to analyze the performance of rotavators fitted with other types of commercial blades. / Thesis (PhD)--University of Pretoria, 2010. / Civil Engineering / unrestricted

[pt] Neste estudo é apresentada a análise da interação da luz laser de alta potência com rochas nos processos de perfuração por fragmentação térmica. O objetivo principal do trabalho é estabelecer, através de um estudo experimental, a possibilidade de utilizar a tecnologia a laser na perfuração de rochas duras, tais como o granito, quartzo, entre outros. Sua motivação encontra-se na aplicação de novas tecnologias para desenvolver ferramentas que melhorem a eficiência no processo de perfuração de poços (maior taxa de penetração), e conseguir retirar a maior quantidade de material fragilizado pela irradiação do laser. Para isto, foi necessário fazer uma montagem opto–mecânica envolvendo um sistema de limpeza que ajudasse a remover o material fragilizado pela ação do laser, usando-se gás de nitrogênio a alta pressão. Foram analisados diferentes intervalos de tempo de exposição da radiação do laser nas rochas, para avaliar a taxa de volume retirado, e a quantidade de energia específica requerida para perfurar diferentes materiais, em função da potência e do tempo de irradiação do laser. Seguindo a revisão bibliográfica na seleção do material, foram escolhidos três tipos de materiais (granito branco, granito cinza e travertino) conhecidos comercialmente no Brasil e que têm similitude (na composição química) com as rochas encontradas nas formações do Pré-sal. A partir desta seleção, foi indispensável conhecer a composição química dos materiais através de fluorescência, raios X, e Microscopia de Varredura (MEV). Além disso, estudou-se o comportamento termomecânico das rochas carbonáticas através de análises térmicas (Termogravimetria e Análise Térmico Diferencial), para identificar e compreender os fenômenos envolvidos no processo de perfuração. Os resultados obtidos são analisados para parametrizar as variáveis em consideração, melhorando as condições do processo de perfuração por fragmentação térmica, dependendo do material estudado. / [en] This study presents the analysis of the interaction of high power laser light with rocks in thermal fragmentation drilling processes. The main objective of the work is to establish, through an experimental study, the possibility of using laser technology in the drilling of hard rocks, such as granite, quartz and others. The motivation is the application of new technologies to develop tools that improve the efficiency in the well drilling process (higher penetration rate), and to be able to remove the largest amount of material weakened by laser irradiation. For this, it was necessary to make an opto-mechanical assembly involving a cleaning system that would help to remove the material weakened by the action of the laser, using nitrogen gas at high pressure. Different exposure time intervals of laser radiation in the rocks were analyzed to evaluate the volume rate removed and the amount of specific energy required to drill different materials, depending on the power and irradiation time of the laser. Following the literature review in selecting the material, three types of materials (white granite, gray granite and travertine) known commercially in Brazil and that are similar (in chemical composition) to the rocks found in the pre-salt formations were chosen. From this selection, it was essential to know the chemical composition of the materials through fluorescence, X-rays, and Scanning Microscopy (SEM). In addition, the thermomechanical behavior of the carbonate rocks wasstudied through thermal analysis (Thermogravimetry and Differential Thermal Analysis) to identify and understand the phenomena involved in the drilling process. The results obtained are analyzed to parameterize the variables under consideration, improving the conditions of the drilling process by thermal fragmentation, depending on the material studied.

This thesis dwells on program creating in program environment Excel, in accordance with submission from submitter. Program is going to be able solve all required values. This thesis has four parts. First part is oriented on problems of urban mass transportation a methods of specific energy consumption. Second part contains program flowchart and program description. Third part contains theoretical solution of specific energy consumption and theoretical comparison of computing methods. Last part contains numerical substitution in an equations and calculating of their values.

Dans l’optique de la conception et du développement d’un siège aéronautique et afin derespecter la règlementation sécuritaire en vigueur, la structure du siège développé doitpermettre une dissipation rapide de l’énergie perçue en cas de crash aérien (Fig. 1), ceci dansle but de protéger les passagers. La majorité des systèmes intégrés à la structure des sièges etpermettant cette absorption d’énergie (Fig. 2) est constituée de composants métalliques qui sedéforment plastiquement pour dissiper l’énergie due au crash. Actuellement, l’industrie et larecherche se tournent vers les matériaux composites pour substituer de tels systèmes.Cependant le comportement de ces matériaux lors de sollicitations mécaniques sévères estfortement différent des matériaux métalliques, notamment dû au fait que les mécanismesd’endommagement sont très distincts.Le but de cette étude portant sur des structures tubulaires composites est d’évaluer leurcapacité à dissiper l’énergie. A cette fin, différentes stratifications ont été testées encompression (Fig. 3 et 4) dans le but de déterminer leur comportement, comparer leurspropriétés et calculer leurs valeurs de SEA (absorption d'énergie spécifique, en kJ.kg-1)servant à évaluer leur aptitude à dissiper l’énergie engendrée en cas de crash. Ces dernièressont issues des courbes effort-déplacement obtenues lors des essais d’écrasement (Fig. 5). Lesdifférents essais de compression ont été instrumentés et suivis au moyen de caméras rapides etdes images post-essais ont été réalisées par tomographie pour comprendre les mécanismesd’endommagement mis en jeu (Fig. 4 et 6). Ces essais ont été réalisés à vitesse de chargementquasi-statique puis dynamique et selon diverses conditions limites. Les différents résultats decomportement en compression sont également utilisés dans le but de construire et enrichir unmodèle de calcul par éléments finis (Fig. 7 et 8) permettant de simuler la réponse de structurescomposites de différentes natures soumises au crash en intégrant la géométrie et lacomposition de la structure (Fig. 8).L’objectif de ce travail de recherche est ainsi d’évaluer l’énergie pouvant être dissipée par desstructures tubulaires composites, de comparer les absorptions induites par des structurescomposites de compositions différentes, et/ou bi-matériaux, et enfin de fournir un modèleéléments finis représentant le comportement de structures composites en compression jusqu’àl’endommagement et la ruine de la structure.Il a ainsi été établi qu’en chargement statique, un stratifié unidirectionnel orienté à 0° etstabilisé par des plis de tissus répond fortement aux attentes en terme de dissipation d’énergie,mais pas en sollicitation dynamique. Dans ce cas, une stratification à 90° semble plusadéquate. D’autre part, un confinement forcé vers l’intérieur est avantageux dans la plupartdes cas, réduisant le pic d’effort initial sans diminuer drastiquement la valeur de SEA. / With the perspective of the design and development of an aircraft seat and in order to respectthe safety regulations in effect, the structure of the developed seat must allow for a swiftdissipation of the energy received in the event of an aircraft crash (Fig. 1) so as to protect thepassengers. The majority of systems integrated into the seats structure and allowing energydissipation (Fig. 2) consists of metal components that sustain plastic deformation to dissipatethe energy induced by the crash. Currently, industry and research sectors are turning theirfocus towards composite materials to substitute such systems. However, the behavior of thesematerials during severe mechanical stress is strongly different from metallic materials, inparticular due to the fact that damage mechanisms are very distinct.The purpose of this study on composite tubular structures is to evaluate their ability todissipate the energy. To this end, different laminate structures were tested in compression(Fig. 3 and 4) in order to identify their behavior, compare their properties and calculate theirSEA value (Specific Energy Absorption, in kJ.kg-1) used to evaluate their capacity to dissipatethe energy generated during a crash. Those are resulting from the load-displacement curvesobtained during the crushing tests (Fig. 5). The various compression tests were instrumentedand monitored by means of rapid imaging cameras and post-crushing tomographic imaginghas been realized in order to understand the damage mechanisms involved (Fig. 4 and 6).Testing has been carried out under quasi-static and dynamic loading and using severalboundary conditions. The different results of compression and crushing behavior are also usedin order to build and improve a finite element calculation model (Fig. 7 and 8) allowing tosimulate the response of composite structures of different natures subjected to crash byintegrating the geometry and the composition of the structure (Fig. 8).The objective of this research work is thus to evaluate the energy that can be dissipated bycomposite tubular structures, to compare the absorption values induced by compositestructures of different compositions, and/or bi-materials, and, finally, to provide a finiteelement model representing the behavior of composite structure submitted to compressionuntil damage and fracture of the structure.It has consequently been established that in static loading, a unidirectional laminate orientedat 0° and stabilized by woven plies strongly meets the expectations in terms of energydissipation, but that is not the case in dynamic loading. In this case, a 90° stratification seemsmore adequate. Incidentally, an inner constrained containment is more effective in most cases,reducing the initial peak load without drastically reducing the SEA value.

I detta examensarbete studeras kommande energikrav för byggnader i Sverige och i synnerhet kraven på specifik energianvändning. Detta mot bakgrund av EU-kommissionens och EU-parlamentets direktiv, EPBD2, om nära nollenergibyggnader 2020. Därefter bearbetas ett förslag på en ny ytterväggskonstruktion som med lägre U-värde än den befintliga ytterväggen ska sänka Fiskarhedenvillans olika hustypers specifika energianvändning. Syftet med sänkningen är att möjliggöra för Fiskarhedenvillan att uppfylla de kommande energikraven. Det är många parametrar som måste uppfyllas och det nya ytterväggsförslaget analyseras förutom ur energisynpunkt även med hänsyn till statik, fukt och kostnad. Beräkningar för statik och specifik energianvändning har gjorts för ett referenshus. Resultatet av att byta ut den befintliga ytterväggskonstruktionen mot det framarbetade förslaget med ca 33 % lägre U-värde gav endast en sänkning med ca 6 % av den specifika energianvändningen. För att sänka referenshusets specifika energianvändning ytterligare bör även resterande delar av klimatskalet förbättras samt ett annat uppvärmningssätt väljas. Avslutningsvis diskuteras resultatet och vi lämnar rekommendationer för fortsatta studier. / This thesis studies future energy requirements for buildings in Sweden and in particular the requirements for specific energy use. This is in light of the European Commission and European Parliament Directive, EPBD2, on nearly-zero energy buildings 2020. A proposal for a new exterior wall construction in Fiskarhedenvillan houses with lower U-value than the existing exterior wall is analyzed. The purpose of the new wall is to reduce the specific energy use to enable Fiskarhedenvillan to meet the future energy requirements. There are many parameters that must be considered. The proposed new exterior wall construction is analyzed not only from the energy point of view but also with regard to statics, moisture and cost. Calculations for the statics and the specific energy use have been made for a reference building. The changed design of the exterior wall resulted in a reduction of the U-value with 33 % but only 6 % of the specific energy use. A further reduction of the specific energy use for the reference house requires improved design of the remaining building envelope and a new heating method. Furthermore the results are discussed and recommendations for further studies are given,

No description available.

För att minska energiförbrukningen i Sverige krävs att befintliga byggnaderen ergieffektiviseras. Det finns även befintliga lokaler i landet som är i behov av en sänkt energiförbrukning. Det sker ständigt initiativ kring arbete med energieffektivisering av framför allt bostadshus. När energiförbrukning ska sänkas i industrilokaler läggs fokus på att minska energiåtgången i de invändigaprocesserna men inte i det omgivande klimatskalet där transmissionen utgör en stor del av energiläckaget. Syftet med arbetet är att öka kunskapen om energieffektiva åtgärder vid renovering av klimatskal hos industrilokaler. Målet ä ratt ta fram olika lösningsförslag som reducerar energiläckaget vid renovering av befintliga industrilokaler anpassat till projektet Dalern. Projektet Dalern är en byggnad uppförd på Åland vid 1990 som används vid fallstudie av förbättrade tekniska lösningar. I rapporten behandlas följande tre frågeställningar. Vilka metoder finns för att energieffektivisera klimatskal hos industrilokaler? Vilka alternativ är mest energieffektiva? Vilka tekniska lösningar skulle fungera i projektet Dalern? För att besvara dessa frågeställningar har en litteraturstudie över vanliga, energisparande renoveringsmetoder utförts. Dokumentstudier har genomförts av referensobjektet Dalerns ritningar. Studien har resulterat i en fallstudie där olika åtgärder beräknats för att se vilka potentialer det finns att energieffektivisera klimatskalet. De resultat som framkommit av arbetet är att det finns många olika metoder att energieffektivisera framför allt husbyggnader. De åtgärder som ger en mest energieffektiv besparing är framför allt byte av fönster och dörrar samt tilläggsisolering av tak och väggar. I fallstudien har olika åtgärder beräknats med handberäkning och med hjälp av energiberäkningsprogrammet VIP-Energy. Byggnadsdelar, möten mellan byggnadsdelar och hela referensobjektets energianvändning har beräknats. Eftersom rapportens tyngdpunkt är energieffektivisering har värmeövergång, köldbryggor och specifik energianvändning beräknats med omsorg. Andra faktorer som tagits hänsyn till är fukt, lufftäthet och brand. Uträkningen i energiberäkningsprogrammet har resulterat i att referensobjektets genomsnittliga värmeövergång kan minska med cirka 30 % vid användning av rätt åtgärder. Referensobjektets specifika energianvändning kan minskas med cirka 33% efter åtgärder som enbart berör klimatskalet. / It’s necessary to make existing buildings more energy efficient in order to reduce the energy consumption in Sweden. There are also existing premises in the country which are in need of reduced energy consumption. Initiatives on energy efficiency takes place continuously. Particularly in residential buildings. When the energy consumption is to be reduced in industrial facilities, the focus is on reducing the consumption of the internal processes. The building envelope where the transmission is a major energy leakage is often forgotten. The purpose is to increase the knowledge of energy-efficient renovation of industrial facilities. The project Dalern is an industrial facility which was built in Åland in 1990. The building is used in a case study of improved technical solutions. Three following questions are covered by this report. Which methods are available to make the building envelope of industrial facilities more energy efficient? Which options are most energy efficient? Which technical solutions would work in the project Dalern? A literature study of common, energy-saving renovation techniques has been implemented to answer the questions above. Document studies have also been implemented on the project Dalern. The document studies have resulted in a case study where different actions have been calculated to see what potential there is to improve the energy efficiency of the building envelope. The result that has emerged from the work is that there are many different methods to improve energy efficiency, especially in residential buildings. The actions that provide the most energy efficient savings are primarily replacement of windows and doors as well as additional insulation of walls and roofs. In the case study, various actions have been calculated using hand calculations and with use of an energy calculation program called VIP-Energy. Structures, meetings between building components and the entire reference object’s energy consumption have been calculated. Heat transfer, thermal bridges and specific energy has been calculated with care since the report’s emphasis is energy efficiency. Other factors that has been taken in consideration are moist, air leakage and fire. The calculation in VIP-Energy has resulted in the reference object’s average heat transfer can be reduced by about 30 % when using the correct actions. The reference object’s specific energy consumption can be reduced by approximately 33 %. These reductions were affected only by actions that concern the building envelope.

[pt] Um dos maiores desafios na perfuração das rochas carbonáticas, situadas a grandes profundidades, é superar as baixas taxas de penetração que vem sendo obtidas na perfuração de poços verticais e direcionais. Para vencer este desafio, um grande esforço vem sendo desenvolvido em várias linhas de pesquisa, tanto no desenvolvimento de novos conceitos de brocas como na seleção de um sistema de perfuração que apresente um melhor desempenho. Para atingir este objetivo, estão sendo priorizados procedimentos e sistemas de perfuração que apresentem menores níveis de vibração, pois este fenômeno além de reduzir a eficiência da perfuração, também compromete o tempo de vida útil dos equipamentos e, por consequência, acarreta a redução da confiabilidade do sistema e eleva o custo por metro da perfuração. Por conseguinte, novas tecnologias de brocas e sistemas de perfuração estão em desenvolvimento e, dentre as novas tecnologias, podemos diferenciar aquelas que promovem melhorias nas tecnologias convencionais e as tecnologias francamente inovadoras, aquelas que utilizam novos mecanismos para cortar ou fragilizar a rocha. Dentre as tecnologias inovadoras, a perfuração assistida por laser é uma das mais promissoras, nesta versão o feixe da energia radiante tem a função principal de fragilizar a rocha, facilitando o avanço da perfuração. Esta dissertação tem por objetivo realizar uma avaliação das possibilidades de aplicação da tecnologia laser na perfuração de rochas. O meio através do qual o laser deverá atuar nas aplicações futuras é analisado sobre o enfoque das suas propriedades físico-químicas. Dessa forma, o conhecimento da interação com o fluido de perfuração é o ponto de partida para a análise de viabilidade. Inicialmente, análises de absorção ótica foram realizadas em alguns tipos de fluido utilizados na indústria do petróleo e, na sequência, foram realizados testes de bancada com um dispositivo eletro-mecânico, especialmente desenvolvido, para servir de base para o laser, com potência máxima de 1500 W, direcionado sobre amostras de rochas carbonáticas. A análise de absorção ótica tem por objetivo compreender melhor o processo de interação do laser com o fluido de perfuração. Os testes de absorção ótica foram realizados para avaliar a absorção da luz, na faixa de comprimento de onda entre 800 nm até 1200 nm. A partir destas informações foi dado o primeiro passo no conhecimento da interação com o fluido de perfuração. Na seqüência da abordagem, um resumo, em nível de pesquisa bibliográfica é apresentado com os estudos, análises e testes de bancada já realizados por vários pesquisadores para verificar o estágio de desenvolvimento desta tecnologia inovadora. A partir deste conhecimento, será possível fazer uma inferência sobre as reais possibilidades desta tecnologia e iniciar um levantamento preliminar sobre os pontos considerados críticos para a sua aplicação, no cenário de perfuração de um poço de petróleo. O cenário de perfuração, como se sabe, é um ambiente agressivo, sujeito a altas vibrações, temperaturas e pressões elevadas. Para concluir, serão apresentados os resultados obtidos em teste de bancada com dispositivo especificamente construído para a fundamentação das conclusões da dissertação. Dentre os aspectos mais relevantes, podemos mencionar: a determinação da durabilidade do sistema, considerando a resistência da lente de focalização ao aquecimento provocado pelo laser e, também, uma avaliação da eficiência do processo sob o ponto de vista do valor obtido para a energia específica. Em resumo, o objetivo final dessa dissertação é o de concentrar em um documento as informações mais atualizadas sobre a utilização do laser na perfuração de rochas e apresentar uma análise, ainda que preliminar, sobre os possíveis pontos de melhoria que permitam viabilizar esta tecnologia no futuro. / [en] One of the biggest challenges in drilling the carbonate rocks located at great depths is to overcome low penetration drilling rates that have been obtained in vertical and directional wells. To overcome this challenge, a great effort is being developed on multiple lines of research. All of them are focused in new concepts of drilling procedures and the selection of a drilling system that presents a better performance. To achieve this goal, new procedures are being designed and drilling systems with lower vibration levels are under development. Vibration reduces the efficiency of drilling, also decreases the lifetime of equipment and consequently causes a reduction in reliability of all system and raises the drilling costs. Consequently, new drill bit technologies and drilling systems are being developed and, among the new technologies we can differentiate those that only promote improvements in conventional technologies and those innovative technologies, in which new mechanisms to cut or weaken the rock are used. The drilling assisted laser is one of the most promising mechanism in which the radiant energy beam has the primary function to weaken the rock increasing the performance of drilling process. This dissertation aims to perform an assessment of the possibilities of laser technology in rock drilling applications. The laser will have to pass through the drilling fluid in the future applications so it is very important to understand their physicochemical properties and their mutual interaction. For this reason, the knowledge of the interaction with the drilling fluid is the starting point for this work. First of all, it will be accomplished an analysis of optical absorption in some types of fluid used in the oil industry. After that, it will be performed bench testing with an electro-mechanical device that will support a laser whose maximum power can reach 1500 W and it will be pointed to carbonate rock samples. The optical absorption analysis aims to better understand the interaction of the laser with the drilling fluid. The optical absorption tests are performed to evaluate the absorption of light in the wavelength range from 800 nm to 1200 nm. From this information, it will be taken the first step to understand the interaction with the drilling fluid, which is the starting point for the feasibility study of the use of lasers. Following the approach, a literature review will be presented with the studies, analysis and bench testing already conducted by various researchers to check the stage of development of this new technology. Taking into account this knowledge, it will be possible to make an initial approach about the actual possibilities of this technology and initiate a preliminary survey on the questions that are critical to its application in a drilling scenario in the well construction, an aggressive environment which is subject to high vibrations, high temperatures and pressures. To conclude, we present the results obtained in bench testing with device specifically built for supporting the conclusions of the dissertation. Among the most relevant aspects, we can mention the durability of the system, considering the focusing lens lifetime under the heating effects caused by the laser. Another point, it is to make an evaluation of the performance of drilling process, considering the specific energy. In summary, the ultimate goal of this dissertation is to concentrate in a single document the most current information about the use of laser drilling and present an analysis, though preliminary, about the possible improvement points that will allow the feasibility of this technology in the future.

La desintegració és una etapa important en la recuperació de paper vell, ja que té importants conseqüències en consum d'energia i en el comportament de les etapes posteriors.Per això els objectius es centren en analitzar la desintegració des del punt de vista del temps de desintegració, els aspectes energètics, modelització de la màquina de desintegració utilitzada i anàlisi dels factors de cisallament calculats com a mesura global de les forces implicades en la desintegració. Els autors que hi han treballat donen diferents explicacions a aquestes forces. Fins avui només s'ha pogut avaluar qualitativament la influència que tenen cada un dels mecanismes en el temps necessari per a desintegrar i en el consum energètic. Les característiques reològiques de les suspensions papereres, i el seu comportament no newtonià tenen una clara influència en el consum energètic i les forces de desfibrat en el desintegrador.Els experiments de desintegració s'han realitzat en un púlper convencional, amb tres tipus de paper recuperat: paper estucat d'alta qualitat imprès offset (PQ), paper revista estucat imprès en color (PR), paper blanc imprès en impresora làsser (PF).Anàlisi del temps de desintegracióPer cada un del papers estudiats (PQ, PR i PF), les fraccions màssiques des de 0.06 fins a la màxima que estat possible per cada paper (de 0.14 a 0.18), i a dues velocitats d'agitació diferents, s'ha determinat el temps de desintegració (tD) fins a aconseguir un índex de Sommerville de 0.01%. S'obté que en augmentar la fracció màssica disminueix potencialment el temps de desintegració. S'ha estudiat la velocitat de desintegració, la producció teòrica del púlper en cada cas, i la seva relació amb les forces d'impacte i de fregament que produeixen la desintegració.Aspectes energèticsEl consum específic d'energia (SEC), definit com l'energia consumida per a desintegrar 1 kg de paper recuperat, disminueix molt en augmentar Xm, ja que a més de disminuir l'energia consumida en cada desintegració, el contingut en paper és més elevat. Pel disseny de desintegradors, cal tenir en compte que en augmentar Xm i en augmentar la velocitat, sempre augmenta la potència consumida. Però així com els beneficis de treballar a Xm alt són de 10 vegades en termes de SEC i de producció, l'augment de potència és només de l'ordre de 2 vegades la necessària respecte de la Xm baixa. Viscositat aparent i energia de fluiditzacióS'estudia la relació entre el temps de desintegració, les forces de fregament i els valors de viscositat aparent de la bibliografia. Per cada paper i velocitat s'ha observat que el consum específic d'energia disminueix en funció de la viscositat aparent.Reologia del púlperUtilitzant el mètode de Metzner i Otto (1957) per determinar la viscositat aparent mitjana de les suspensions papereres, modificat per Roustan, s'ha caracteritzat el pulper mitjançant el model: Np= K· Rex·Fry S'han utilitzat dissolucions de glicerina com a fluid newtonià per a calcular les constants d'ajust, i a partir d'aquí, aïllar la viscositat aparent en funció de la potència neta i els paràmetres d'agitació.La viscositat aparent, d'acord amb Fabry (1999) es substitueix pel concepte de factor de cisallament.Factor de cisallamentCalculat el factor de cisallament per a cada paperot i condicions d'agitació, s'ha relacionat amb Xm, SEC, tD, consum de potència, potència instal·lada i fracció cel·lulòsica. El factor de cisallament és un paràmetre útil per a quantificar les forces globals implicades en la desintegració. / Disintegration is an important stage in paper recovery and it has important consequences in energy consumption and in the following stages.The objectives of this thesis are focussed in analyzing disintegration considering disintegration time, power aspects, modelisation of the disintegration machine and analysis of the calculated shear factors as a global measurement of the forces implied in the disintegration.Until now, it has only been possible a qualitative evaluation of the influence of every mechanism in the time necessary to disintegrate the pulp, and in the power consumption.Rheological characteristics of suspensions and their non-Newtonian behaviour it is known that clearly influence power consumption and defibering forces acting during repulping. Disintegration experiments have been made in a conventional pulper, with three types of recovered paper: high quality coated printed offset paper, magazine coated colour printed paper and white laser printed paper.Analysis of disintegration timeTime necessary to achieve a Somerville index of 0.01%, was determined for each paper studied, at mass fractions ranging from 0,06 until the maximum possible for each type of paper (0,14 or 0,18) and at two different agitation speeds. It has been found that when increasing the mass fraction, disintegration time decreases potentially. Disintegration speed and theoretical production of pulp have been studied in each case, and they have been related with friction and impact forces.Power aspects Specific energy consumption (SEC) defined as the energy consumed during disintegration of 1 kg of recovered paper, was reduced with increasing mass fraction (Xm), because the energy consumed during disintegration decreases and the pulp contend in the pulper is higher. And increase of Xm and pulper agitation speed always increases the power consumed. An increase of only 2 times of power consumption (due to working at high Xm) produces benefits in SEC and production of 10 times.Apparent Viscosity and fluidisation energy Relation between disintegration time, friction forces and apparent viscosity were studied. For each paper and speed it has been observed that SEC was reduced when increasing apparent viscosity.Rheology of pulper Using Metzner and Otto methodology to determine average apparent viscosity of suspensions, modified by Roustan, pulper was characterized by means of model Np=K·Rex·Fry. Glycerine dissolutions have been used as Newtonian fluid to calculate constants of adjustment, and from here, apparent viscosity was determined from net power and agitation parameters. Apparent viscosity, in agreement with Fabry, is replaced by the concept of shear factor.Shear FactorOnce calculated the shear factor for each type of paper and conditions of agitation, the values obtained have been related to Xm, SEC, td, power consumption, installed power and cellulose fraction. Shear factor is a useful parameter to quantify the global forces acting in disintegration process.

Philosophiae Doctor - PhD (Chemistry) / Supercapacitors, also known as ultracapacitors or electrochemical capacitors, are considered one of the most important subjects concerning electricity or energy storage which has proven to be problematic for South Africa. In this work, graphene oxide (GO) was supported with platinum, silver and copper nanoparticles anchored with dodecylbenzenesulphonic acid (DBSA) doped polyaniline (PANI) to form nanocomposites. Their properties were investigated with different characterization techniques. The high resolution transmission electron microscopy (HRTEM) revealed GO's nanosheets to be light, flat, transparent and appeared to be larger than 1.5 ?m in thickness. This was also confirmed by high resolution scanning electron microscopy (HRSEM) with smooth surfaces and wrinkled edges observed with the energy dispersive X-ray analysis (EDX) confirming the presence of the functional groups such as carbon and oxygen. The HRTEM analysis of decorated GO with platinum, silver and copper nanoparticles (NPs) revealed small and uniformly dispersed NPs on the surface of GO with mean particle sizes of 2.3 ± 0.2 nm, 2.6 ± 0.3 nm and 3.5 ± 0.5 nm respectively and the surface of GO showed increasing roughness as observed in HRSEM micrographs. The X-ray fluorescence microscopy (XRF) and EDX confirmed the presence of the nanoparticles on the surface of GO as platinum, silver and copper which appeared in abundance in each spectra. Anchoring the GO with DBSA doped PANI revealed that single GO sheets were embedded into the polymer latex, which caused the DBSA-PANI particles to become adsorbed on their surfaces. This process then appeared as dark regions in the HRTEM images. Morphological studies by HRSEM also supported that single GO sheets were embedded into the polymer latex as composite formation appeared aggregated and as bounded particles with smooth and toothed edges.