No description available.

This study evaluated effects of driving torques on screw direct withdrawal resistance (SDWR) from wood-based composites. The results on the screw seating torques indicated that the face-grain orientation of each material type had the highest mean load. The face-grain orientation of OSB had the highest mean load of 11.1 lb.in., and the MDF had the lowest mean load of 7lb.in.. For the screw stripping torques, the result showed the face-grain orientation of each material type had the highest mean load. The face-grain orientation of OSB had the highest load of 55.9 lb.in. Effects of torque levels on SDWR, the results indicated that the SDWR was lower at the torque level closer to the seating and stripping torque levels in OSB, whereas the SDWR was only lower in the torque level closer to the stripping torque within MDF and PB. Face-grain orientations of the each wood material had the highest SDWR.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / One of the steps in the technical analysis of water supply systems are simulations of the conditions of equilibrium a distribution network. In order to estimate the parameters of a hydraulic network, from observed data hydraulic loads, there is developed a computational method. In general, the physical parameters of the network as unknown friction factors, the absolute roughness, diameter and the identification and quantification of leaks are unknown quantities. In this study, the focus will be on the identification of diameters through a combination Transient Reverse method - Genetic Algorithm with the MTI - AG using the method of characteristics - MOC the solution of equations of motion for a transient flow in ducting . The use of elitism operator is used to evaluate the effects on the identification of the diameter transient conditions. The steady state conditions are known. The accuracy of the MTI model developed AG are evaluated by two-networks example, used in the proposed calibration problem. The effect of the transient is achieved by changing demand of the nodes of the distribution network. The performance of the proposed method is verified by evaluating the variability of the transient size of the record and possible reading errors in the hydraulic loads and diameters / Uma das etapas na anÃlise tÃcnica de sistemas de abastecimento de Ãgua sÃo as simulaÃÃes das condiÃÃes de equilÃbrio de uma rede de distribuiÃÃo. A fim de se estimar os parÃmetros de uma rede hidrÃulica, a partir de dados observados de cargas hidrÃulicas, desenvolve-se um mÃtodo computacional. Em geral, os parÃmetros fÃsicos da rede desconhecidos como fatores de atrito, rugosidades absolutas, diÃmetros e a identificaÃÃo e quantificaÃÃo de vazamentos sÃo grandezas desconhecidas. Nessa pesquisa, o enfoque serà dado na identificaÃÃo dos diÃmetros, atravÃs de uma combinaÃÃo do MÃtodo Transiente Inverso - MTI com o Algoritmo GenÃtico â AG, utilizando o MÃtodo das CaracterÃsticas â MOC na soluÃÃo das equaÃÃes do movimento para escoamento de transiente em rede de tubos. A utilizaÃÃo do operador elitismo serà utilizada para avaliar os efeitos produzidos na identificaÃÃo dos diÃmetros em condiÃÃes transientes. As condiÃÃes de regime permanente sÃo conhecidas. A precisÃo do modelo MTI com AG desenvolvidos sÃo avaliados atravÃs de duas redes-exemplo, utilizado no problema de calibraÃÃo proposto. O efeito do transiente à alcanÃado atravÃs da mudanÃa de demanda de um dos nÃs da rede de distribuiÃÃo. O desempenho do mÃtodo proposto à verificado avaliando-se a variabilidade do tamanho do registro transiente e de possÃveis erros de leituras nas cargas hidrÃulicas e nos diÃmetros

The natural hip joint in healthy people has a very low friction with very little (or no) wear. It works as a dynamically loaded bearing and is subjected to about 1-2 million cycles of loading per year. The applied load is the body weight which is tripled when walking and even higher during other activities such as running and jumping. Unfortunately these joints are not always healthy due to various causes such as fractures or disease leading to severe pain which necessitates joint replacement. Currently, the orthopaedic industries are working towards developing an ideal artificial hip joint with low wear, low friction, good lubrication, better fixation/stability and biocompatibility. Many different designs and materials have been investigated with some promising new implants which can be used depending on patients' individual need (large or small joint), activity and age. In this work, two types of artificial hip joints were tested for friction and lubrication studies: Metal-on-Metal (MoM) Biomet hip resurfacing ReCaps with large diameters (>35-60 mm) and different diametral clearances (~ 60-350 µm), and Zirconia Toughened Alumina (ZTA) heads against carbon-fibre-reinforced poly-ether-ether ketone (CFR PEEK) cups with different diameters (>35-60 mm) and diametral clearances (60-1860 µm). Seven serum-based lubricants with different viscosities were used with and without carboxy methyl cellulose (CMC) additions as gelling agent to increase viscosity depending on the CMC content. The maximum load applied was 2000 N for the stance phase with a minimum load of 100 N for the swing phase. A Pro-Sim friction hip simulator was used to investigate the frictional torque generated between the articulating surfaces so as the friction factor can be calculated. Stribeck analysis was then employed to assess the mode of lubrication. For the metal-on-metal hip resurfacing joints, the friction factors were in the range 0.03-0.151 and those for the ZTA ceramic heads versus CFR PEEK cups were in the range 0.006-0.32. Stribeck analyses showed mainly mixed lubrication for both MoM and ZTA ceramic-on-CFR PEEK joints. The experimental results were in agreement with most of the theoretical calculations suggesting mixed lubricating regimes at low viscosities and moving on to fluid film lubrication at higher viscosities. Joints with larger-diameters, lower clearances and lower surface roughness exhibited a higher lambda ratio suggesting improved lubrication. Viscosity flow curves for the serum-based lubricants having viscosity ≤ 0.00524 Pas showed non-linear relationship between viscosity and shear rate indicating non-Newtonian flow with pseudoplastic or shear-thinning characteristic, i.e. viscosity decreased as shear rate increased up to shear rates of ~ 1000 s⁻¹. However, at shear rates greater than 1000 s⁻¹ Newtonian flow became dominant with almost constant viscosity, i.e. a linear relationship between shear stress and shear rate. On the other hand, viscosity flow curves for the lubricants with viscosity ≥ 0.0128 Pas showed non-Newtonian behaviour up to a shear rate of 3000 s⁻¹ with shear-thinning characteristic.

A tese buscou identificar, a partir da análise da cadeia produtiva de produtos de base florestal, as oportunidades para aproveitamento da madeira roliça dos gêneros Eucalyptus e Pinus, com pequeno diâmetro, para produção de painéis estruturais de vedação destinados a habitação social. A madeira como material construtivo renovável, e segundo as dimensões da sustentabilidade, econômica e ambiental, apresenta as seguintes potencialidades: plantio e manejo florestal sustentável; adequação a diversos sistemas estruturais e construtivos; baixos consumos de energia e baixa geração de resíduos no processo de produção; desmontagem e aproveitamento dos resíduos no processo de transformação. O método adotado para o desenvolvimento do produto painel foi baseado, na análise e aperfeiçoamentos sucessivos a partir da avaliação dos dados coletados na fase experimental (processo de produção). As variáveis consideradas foram: facilidade de produção (homem/minuto, hora/equipamento e ferramentas), volume de resíduos gerados no processamento, custos e facilidade de montagem do painel. Os critérios adotados na avaliação de desempenho técnico foram: estrutural, estanqueidade visual e durabilidade. Na avaliação da sustentabilidade ambiental foram: uso de materiais de fontes renováveis; baixo consumo energético; redução de resíduos gerados. A sustentabilidade econômica foi avaliada considerando os critérios de: facilidade de produção; facilidade de montagem; produção em escala; baixos custos dos materiais empregados. Foram desenvolvidos e avaliados 10 projetos segundo os critérios considerados, concluindo-se com a proposição do produto painel estrutural composto por 1/2 peças roliças de eucalipto com pequeno diâmetro, curtas, justapostas e pregadas à chapa OSB (oriented strand board). O painel tem dimensões fracionadas na altura e na largura da chapa (1,22 x 2,44 m), nas seguintes medidas: 0,61 x 2,44; 0,61 x 1,22; 1,22 x 1,22 m; 1,22 x 2,44 m. Esta composição do painel viabiliza o melhor aproveitamento das peças chamadas de “metrinho", as quais 100% são destinadas atualmente para queima na geração de energia (desde fornos de padarias até fornos industriais). A proposta mostrou ser viável e pode-se constatar a sua facilidade de execução, mesmo em situações precárias de maquinários. A adoção dessas simplificações construtivas para a produção de componentes construtivos para habitações pode representar uma oportunidade de redução do tempo de execução e dos custos de produtos que atendam ao setor da habitação de baixa renda. A proposta apresenta ainda uma contribuição para a melhoria nas condições de moradia e redução dos impactos negativos ao meio ambiente, gerados pela construção civil, na utilização de materiais não renováveis. / The purpose of this work is to identify, from the analysis of the production chain of forest based products, the chances of making use of small diameter round-wood of the Eucalyptus and Pinus types, for the production of sealing structural panels destined for social housing. Wood as a renewable building material – and, in accordance with the environmental and economic dimensions of sustainability – presents the following potentialities: sustainable forest planting and handling; adequacy to several building and structural systems; low energy consumption and low residual outcome during the production process; dismantling and reuse of the remnants in the transformation process. The method adopted for the development of the panel product was grounded on the analysis and consecutive improvement, which was based on the evaluation of the data collected in the experimental phase (production process). The following variables were considered: production easiness (man/minute, time/equipment and tooling), amount of remnant generated by the processing, cost and panel mounting easiness. The criteria adopted in the evaluation of technical execution were the following: structural, visual tightness and durability. The following criteria were used in the environmental sustainability evaluation: use of materials from renewable sources; low energy consumption; reduction of residual outcome. The economic sustainability was evaluated taken the following criteria into consideration: production easiness; mounting easiness; mass production, low cost of the materials used. Ten projects have been developed and evaluated according to the considered criteria, and the structural panel product comprising juxtaposed, short, small diameter, eucalyptus, half round-wood pieces, nailed to OSB (oriented strand board) plate, was proposed. The panel has dimensions fractionized in the height and the width of the plate (1.22 x 2,44 m), in the following measures: 0.61 x 2.44; 0.61 x 1.22; 1.22 x 1.22 m; 1.22x 2.44 m. This panel composition enables for best utilization of the so called metrinho (small pieces) pieces, which, nowadays, are 100% used in burning for the generation of energy (from bakery to industrial ovens). The proposal has shown to be doable and of easy execution, even in precarious machinery situations. The adoption of these building simplifications for the production of building components for housing may represent an opportunity to reduce the execution time, as well as the products cost, in order to serve the low income housing sector. The proposal also presents a contribution to the improvement of housing conditions and to the reduction of negative environmental impacts, caused by the civil construction through the use of non-renewable materials.

Submitted by Cláudia Bueno (claudiamoura18@gmail.com) on 2016-03-03T20:59:22Z No. of bitstreams: 2 Dissertação - Rafael Tomaz Parreira - 2015.pdf: 4890640 bytes, checksum: 77343ad4266b8d39c9b9e142b0c167c3 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-03-04T11:31:51Z (GMT) No. of bitstreams: 2 Dissertação - Rafael Tomaz Parreira - 2015.pdf: 4890640 bytes, checksum: 77343ad4266b8d39c9b9e142b0c167c3 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2016-03-04T11:31:51Z (GMT). No. of bitstreams: 2 Dissertação - Rafael Tomaz Parreira - 2015.pdf: 4890640 bytes, checksum: 77343ad4266b8d39c9b9e142b0c167c3 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-10-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Forest Inventory is a se to fimportanttechniquesthatprovidesessentialinformationsfor rationalandsustainableresourcesdrivinginforests. The selectedareacanbecharacteri- zedaboutspeciesquantityandquality.Forest inventories areusedinmanykindofstudies inorderofknowing,forecastingandevaluationinfields.Furthermore,theforestinven- toryalsoallowstoevaluatethetimberstockanditsviability,planningandpreparation ofexplorationtreestandsandpostexploratory.Anessentialinformationisthediameters alongoftreetrunkanditisindispensablefortimbervolume calculation.Currently,fordi- ametermeasuringahugetimeisrequiredandmanymistakesare possibledueinstruments defectsandhumanfailures.Somestudieshaveuseddifferent techniquesforreplacingtra- ditionaldiametermeasuringinstruments,amongthemstands outdeviceswithcapability ofgetdepthdatainthefield.Amongthesedevicesarethedepth camerasthatduethe recentdecreaseofpricehavebecomeverypopularincomputer visionapplications.Inor- dertoassistvolumeestimation,thisworksproposesusingdepthcamerastoconductdata acquisitionandanalisysofEucalyptustreediameters.The modeldevelopediscapable toacquirediametersindifferenttreeheights,howeverthe focusismorespecificallyin getdiametersat0.3,0.7and1.3metersfromtheground.Experimentswereconducted inordertocomparetheproposedmodeltotraditionaltechniquesandtheresultsarevery satisfactory. / O inventário florestal é um conjunto de técnicas importantes que fornece informações essenciais para direcionamento racional e sustentável dos recursos disponíveis nas florestas. Por meio dele é possível a caracterização de uma determinada área e do conhecimento quantitativo e qualitativo das espécies que a compõe. Inventários florestais são utilizado sem vários tipos de levantamentos com a finalidade de reconhecimento,diagnóstico e avaliações no campo florestal. A avaliação de estoque de madeira em estudos de viabilidade, planejamento e preparação de talhões de exploração, bem como, diagnóstico pós-exploratório, exigem inventários específicos. Uma das informações essenciais é o diâmetro ao longo do tronco das árvores, que é imprescindível para o cálculo de volume de madeira. Atualmente, para medir esses diâmetros é demandado um período elevado de tempo, sendo passível de erros gerados por defeitos em instrumentos e/ou falhas dos operadores. Alguns estudos têm utilizado técnicas diferentes para substituir o uso de instrumentos tradicionais na tomada das medidas dos diâmetros, entre elas se destaca o uso de dispositivos que podem obter os padrões de profundidade em cenários que contém árvores. Entre os dispositivos capazes de obter profundidade, está as câmeras de profundidade, que vem se popularizando,tornando-se cada vez mais acessíveis,com isso diversas aplicações de visão computacional vêm sendo desenvolvidas, e são capazes de fazer a extração de informações bastante úteis. Este trabalho propõe a utilização de câmeras de profundidade para realizar análise e aquisição de dados que são usados para estimar diâmetros de árvores do gênero Eucalyptus. O modelo desenvolvido para calcular os diâmetros da base das árvores nas alturas de 0,3;0,7 e 1,3 metros em relação ao solo. O modelo proposto, tem por objetivo, o uso dos diâmetros estimados por câmera de profundidade para o cálculo do volume das árvores de eucalipto apartir método apresentado nos trabalhos relacionados. Foram realizados testes a fim de comparar o desempenho do modelo proposto aos métodos tradicionais.Os resultados obtidos foram considerados bastante satisfatórios.

We show some preliminary 10-37 micron high-resolution spectra taken with the Spitzer Space Telescope in 2008-9 of Mira variables distributed across the M, S and C chemical subclasses. Our entire Spitzer sample of 25 galactic Miras was observed from two to several times during this observing campaign and all have simultaneously measured near-infrared interferometric diameters acquired using the Palomar Testbed Interferometer. Because our sources are very bright for Spitzer IRS (typically 5-100 Janskys), we have excellent signal to noise and for many sources see marked changes in overall flux levels as a function of phase. Further, we are able to identify many strong emission lines and emission features due to silicate and carbon dusts and molecular constituents. We introduce the sample and the design of our experiment, discuss the data reduction required for such bright sources using Spitzer, show several examples of spectra with phase and discuss some preliminary findings. Finally, we discuss future steps for Paper II, to be presented later in the year.

A tese buscou identificar, a partir da análise da cadeia produtiva de produtos de base florestal, as oportunidades para aproveitamento da madeira roliça dos gêneros Eucalyptus e Pinus, com pequeno diâmetro, para produção de painéis estruturais de vedação destinados a habitação social. A madeira como material construtivo renovável, e segundo as dimensões da sustentabilidade, econômica e ambiental, apresenta as seguintes potencialidades: plantio e manejo florestal sustentável; adequação a diversos sistemas estruturais e construtivos; baixos consumos de energia e baixa geração de resíduos no processo de produção; desmontagem e aproveitamento dos resíduos no processo de transformação. O método adotado para o desenvolvimento do produto painel foi baseado, na análise e aperfeiçoamentos sucessivos a partir da avaliação dos dados coletados na fase experimental (processo de produção). As variáveis consideradas foram: facilidade de produção (homem/minuto, hora/equipamento e ferramentas), volume de resíduos gerados no processamento, custos e facilidade de montagem do painel. Os critérios adotados na avaliação de desempenho técnico foram: estrutural, estanqueidade visual e durabilidade. Na avaliação da sustentabilidade ambiental foram: uso de materiais de fontes renováveis; baixo consumo energético; redução de resíduos gerados. A sustentabilidade econômica foi avaliada considerando os critérios de: facilidade de produção; facilidade de montagem; produção em escala; baixos custos dos materiais empregados. Foram desenvolvidos e avaliados 10 projetos segundo os critérios considerados, concluindo-se com a proposição do produto painel estrutural composto por 1/2 peças roliças de eucalipto com pequeno diâmetro, curtas, justapostas e pregadas à chapa OSB (oriented strand board). O painel tem dimensões fracionadas na altura e na largura da chapa (1,22 x 2,44 m), nas seguintes medidas: 0,61 x 2,44; 0,61 x 1,22; 1,22 x 1,22 m; 1,22 x 2,44 m. Esta composição do painel viabiliza o melhor aproveitamento das peças chamadas de “metrinho”, as quais 100% são destinadas atualmente para queima na geração de energia (desde fornos de padarias até fornos industriais). A proposta mostrou ser viável e pode-se constatar a sua facilidade de execução, mesmo em situações precárias de maquinários. A adoção dessas simplificações construtivas para a produção de componentes construtivos para habitações pode representar uma oportunidade de redução do tempo de execução e dos custos de produtos que atendam ao setor da habitação de baixa renda. A proposta apresenta ainda uma contribuição para a melhoria nas condições de moradia e redução dos impactos negativos ao meio ambiente, gerados pela construção civil, na utilização de materiais não renováveis. / The purpose of this work is to identify, from the analysis of the production chain of forest based products, the chances of making use of small diameter round-wood of the Eucalyptus and Pinus types, for the production of sealing structural panels destined for social housing. Wood as a renewable building material – and, in accordance with the environmental and economic dimensions of sustainability – presents the following potentialities: sustainable forest planting and handling; adequacy to several building and structural systems; low energy consumption and low residual outcome during the production process; dismantling and reuse of the remnants in the transformation process. The method adopted for the development of the panel product was grounded on the analysis and consecutive improvement, which was based on the evaluation of the data collected in the experimental phase (production process). The following variables were considered: production easiness (man/minute, time/equipment and tooling), amount of remnant generated by the processing, cost and panel mounting easiness. The criteria adopted in the evaluation of technical execution were the following: structural, visual tightness and durability. The following criteria were used in the environmental sustainability evaluation: use of materials from renewable sources; low energy consumption; reduction of residual outcome. The economic sustainability was evaluated taken the following criteria into consideration: production easiness; mounting easiness; mass production, low cost of the materials used. Ten projects have been developed and evaluated according to the considered criteria, and the structural panel product comprising juxtaposed, short, small diameter, eucalyptus, half round-wood pieces, nailed to OSB (oriented strand board) plate, was proposed. The panel has dimensions fractionized in the height and the width of the plate (1.22 x 2,44 m), in the following measures: 0.61 x 2.44; 0.61 x 1.22; 1.22 x 1.22 m; 1.22x 2.44 m. This panel composition enables for best utilization of the so called metrinho (small pieces) pieces, which, nowadays, are 100% used in burning for the generation of energy (from bakery to industrial ovens). The proposal has shown to be doable and of easy execution, even in precarious machinery situations. The adoption of these building simplifications for the production of building components for housing may represent an opportunity to reduce the execution time, as well as the products cost, in order to serve the low income housing sector. The proposal also presents a contribution to the improvement of housing conditions and to the reduction of negative environmental impacts, caused by the civil construction through the use of non-renewable materials.

Dans ce mémoire, je propose une nouvelle technique optique de mesure de positions relatives 3D, tailles et indices de réfraction d’un ensemble de particules, éclairées par un faisceau laser plan pulsé : l’imagerie interférométrique de Fourier (FII). Dans le cadre de ce travail, les particules sont sphériques, homogènes transparentes et isotropes. Lorsque ces particules sont éclairées, elles se comportent comme des sources d’ondes lumineuses sphériques qui interférent entre elles. L’enregistrement des franges d’interférences et leur analyse par transformation de Fourier peut permettre d’accéder aux caractéristiques des particules. Dans ce mémoire, je décris l’influence des caractéristiques de particules sur les représentations spectrales des franges d’interférences crées par les couples de particules éclairées dans l’espace de Fourier 2D. Les franges d’interférences sont simulées numériquement en utilisant la théorie de Lorenz-Mie. Puis j’aborde le problème inverse en montrant comment il est possible de retrouver les caractéristiques des particules, en me servant de l’optique géométrique et du filtrage spatial par transformation de Fourier. / In this thesis, I propose a new optical technique for measuring 3D relative positions, sizes and refractive indices of a set of particles, which are illuminated by a plane and pulsed laser beam. In this work, the particles are spherical, transparent, homogeneous and isotropic. When these particles are illuminated, they have the behavior of sources of spherical light waves which interfere. The recording of interference fringes and analysisby Fourier transform can measure the characteristics of the particles. I describe the influence of particle characteristics on spectral representations of the interference fringes created by the pairs of particles illuminated in 2D Fourier space. The interference fringes are simulated numerically using the Lorenz-Mietheory. The inverse problem is approached by showing how it is possible to measure the characteristics of particles with geometrical optics and spatial filtering by Fourier transformation.

The natural hip joint in healthy people has a very low friction with very little (or no) wear. It works as a dynamically loaded bearing and is subjected to about 1-2 million cycles of loading per year. The applied load is the body weight which is tripled when walking and even higher during other activities such as running and jumping. Unfortunately these joints are not always healthy due to various causes such as fractures or disease leading to severe pain which necessitates joint replacement. Currently, the orthopaedic industries are working towards developing an ideal artificial hip joint with low wear, low friction, good lubrication, better fixation/stability and biocompatibility. Many different designs and materials have been investigated with some promising new implants which can be used depending on patients¿ individual need (large or small joint), activity and age. In this work, two types of artificial hip joints were tested for friction and lubrication studies: Metal-on-Metal (MoM) Biomet hip resurfacing ReCaps with large diameters (>35-60 mm) and different diametral clearances (~ 60-350 µm), and Zirconia Toughened Alumina (ZTA) heads against carbon-fibre-reinforced poly-ether-ether ketone (CFR PEEK) cups with different diameters (>35-60 mm) and diametral clearances (60-1860 µm). Seven serum-based lubricants with different viscosities were used with and without carboxy methyl cellulose (CMC) additions as gelling agent to increase viscosity depending on the CMC content. The maximum load applied was 2000 N for the stance phase with a minimum load of 100 N for the swing phase. A Pro-Sim friction hip simulator was used to investigate the frictional torque generated between the articulating surfaces so as the friction factor can be calculated. Stribeck analysis was then employed to assess the mode of lubrication. For the metal-on-metal hip resurfacing joints, the friction factors were in the range 0.03-0.151 and those for the ZTA ceramic heads versus CFR PEEK cups were in the range 0.006-0.32. Stribeck analyses showed mainly mixed lubrication for both MoM and ZTA ceramic-on-CFR PEEK joints. The experimental results were in agreement with most of the theoretical calculations suggesting mixed lubricating regimes at low viscosities and moving on to fluid film lubrication at higher viscosities. Joints with larger-diameters, lower clearances and lower surface roughness exhibited a higher lambda ratio suggesting improved lubrication. Viscosity flow curves for the serum-based lubricants having viscosity ¿ 0.00524 Pas showed non-linear relationship between viscosity and shear rate indicating non-Newtonian flow with pseudoplastic or shear-thinning characteristic, i.e. viscosity decreased as shear rate increased up to shear rates of ~ 1000 s-1. However, at shear rates greater than 1000 s-1 Newtonian flow became dominant with almost constant viscosity, i.e. a linear relationship between shear stress and shear rate. On the other hand, viscosity flow curves for the lubricants with viscosity ¿ 0.0128 Pas showed non-Newtonian behaviour up to a shear rate of 3000 s-1 with shear-thinning characteristic. / Ministry of Higher Education, Libya