890 resultados para rolling mill roll
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Biofuels derived from industry waste have potential to substitute fossil fuels (Diesel and Gasoline) in internal combustion (IC) engines. Use of waste streams as fuels would help to reduce considerably life-cycle greenhouse gas emissions and minimise waste processing costs. In this study an investigation into the fuel properties of two waste derived biofuels were carried out, they are: (i) Glidfuel (GF) biofuel - a waste stream from paper industry, and (ii) Palm Oil Mill Effluent (POME) biodiesel - biodiesel produced from palm oil industry effluent through various treatment and transesterification process. GF and POME was mixed together at various proportions and separately with fossil diesel (FD) to assess the miscibility and various physical and chemical properties of the blends. Fuel properties such as kinematic viscosity, higher heating value, water content, acid number, density, flash point temperature, CHNO content, sulphur content, ash content, oxidation stability, cetane number and copper corrosion ratings of all the fuels were measured. The properties of GF, POME and various blends were compared with the corresponding properties of the standard FD. Significance of the fuel properties and their expected effects on combustion and exhaust emission characteristics of the IC engine were discussed. Results showed that most properties of both GF and POME biodiesel were comparable to FD. Both GF and POME were miscible with each other, and also separately with the FD. Flash point temperatures of GF and POME biodiesel were 40.7°C and 158.7°C respectively. The flash point temperature of GF was about 36% lower than corresponding FD. The water content in GF and FD were 0.74 (% wt) and 0.01 (% wt) respectively. Acidity values and corrosion ratings of both GF and POME biodiesel were low compared to corresponding value for FD. The study concluded that optimum GF-POME biofuel blends can substitute fossil diesel use in IC engines.
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Opuntia fícus - indica (L.) Mill is a cactacea presents in the Caatinga ecosystem and shows in its chemical c omposition flavonoids, galacturonic acid and sugars. Different hydroglicolic (EHG001 and EHG002) and hydroethanolic subsequently lyophilized (EHE001 and EHE002) extracts were developed. The EHE002 had his preliminary phytochemical composition investigated by thin layer chromatography (TLC) and we observed the predominance of flavonoids. Different formulations were prepared as emulsions with Sodium Polyacrylate (and) Hydrogenated Polydecene (and) Trideceth - 6 (Rapithix® A60), and Polyacrylamide (and) C13 - 14 I soparaffin (and) Laureth - 7 (Sepigel® 305), and gel with Sodium Polyacrylate (Rapithix® A100). The sensorial evaluation was conducted by check - all - that - apply method. There were no significant differences between the scores assigned to the formulations, howe ver, we noted a preference for those formulated with 1,5% of Rapithix® A100 and 3,0% of Sepigel® 305. These and the formulation with 3% Rapithix® A60 were tested for preliminary and accelerated stability. In accelerated stability study, samples were stored at different temperatures for 90 days. Organoleptic characteristics, the pH values and rheological behavior were assessed. T he emulsions formulated with 3,0% of Sepigel® 305 and 1,5% of Rapithix® A60 w ere stable with pseudoplastic and thixotropic behavior . The moisturizing clinical efficacy of the emulsions containing 3,0% of Sepigel® 305 containing 1 and 3% of EHG001 was performed using the capacitance method (Corneometer®) and transepidermal water lost – TEWL evaluation ( Tewameter®). The results showed t hat the formulation with 3% of EHG001 increased the skin moisturizing against the vehicle and the extractor solvent formulation after five hours. The formulations containing 1 and 3% of EHG001 increased skin barrier effect by reducing transepidermal water loss up to four hours after application.
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Nanoemulsions are emulsified systems, characterized for reduced droplet size (50- 500nm), which the main characteristic are kinect stability and thermodynamic instability. These are promising systems on cosmetic area due to their droplet size that provide different advantages when compared to conventional systems, among others, larger surface area and better permeability. The Opuntia ficus-indica (L.) Mill is a plant cultivated on Caatinga Brazilian biome, which has great socioeconomic importance to region. This plant shows carbohydrates utilized for cosmetic industry as moisturizing active in their chemical composition. The aim of study was to develop, characterize, evaluate stability and moisturizing efficacy of cosmetic nanoemulsions added to Opuntia ficus-indica (L.) Mill extract. Nanoemulsions preparation was made using a low energy method. Different nanoemulsions were formulated varying the ratio of oil, water and surfactant phases beyond xanthan gum (0.5% e 1%) and Opuntia ficus-indica (L.) Mill hydroglycolic extract addition on 1% and 3%. Obtained nanoemulsions were submitted to preliminary and accelerated stability tests. The evaluated parameters monitored were: macroscopic aspect, pH value, droplet size, zeta potential and polydispersion index, during 60 days on different temperatures. Stable formulations were submitted to moisturizing efficacy assessment by capacitance and transepidermal water loss methodologies during 5 hours. Stable samples were white and showed homogeneous and fluid aspect, pH value was inside ideal range (4,5-6,0) to topical application and droplet size under 200nm characterizing these system as nanoemulsions. Developed nanoemulsions did not decrease transepidermal water loss, however increased the water content on stratum corneum, highlighting the nanoemulsions containing 0.5% of xanthan gum and 1% of hydroglycolic extract. This work presents cosmetic moisturizing nanoemulsions composed to vegetal raw material from Brazilian Caatinga with potential to be used on cosmetic area.
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The development of a human individual was a matter of investigation for many thinkers through the history of philosophy. The meanings that this development has taken were, nevertheless, very diversified, involving moral, political, epistemological, aesthetical and even religious aspects. The main agents in this process of development of human individuality are, on the one hand, each individual, who has to strive to improve himself the most, creating and resorting to the means available to that; on the other hand, the fomentalist State also have to take his part in this process, given that such a State has a direct interest in the development of his own citizens; it has to act in such a way that it can foment new and enhance the old existing means that can be used to accomplish the task of developing the human individuality. The goal of this thesis is to investigate the meaning that such development has acquired for the utilitarian philosopher John Stuart Mill, from his conception of individuality.
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The major objectives of this thesis were to determine if foam rolling had any effect on antagonist muscle activation and whether those changes would alter muscular co-activation patterns. The results from this thesis along with current literature will help clinicians to develop adequate exercise prescription for rehabilitative and pre-activity purposes. The existing literature has shown that foam rolling or roller massagers can increase range of motion (ROM), improve performance, and alter pain perception, however little research exists regarding changes in muscle activation following foam rolling. This study developed a reliable method for measuring muscle activation around the knee joint and using that method found that foam rolling the quadriceps can impair hamstrings muscle activation likely due to greater levels of perceived pain when rolling the quadriceps.
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Rolling Isolation Systems provide a simple and effective means for protecting components from horizontal floor vibrations. In these systems a platform rolls on four steel balls which, in turn, rest within shallow bowls. The trajectories of the balls is uniquely determined by the horizontal and rotational velocity components of the rolling platform, and thus provides nonholonomic constraints. In general, the bowls are not parabolic, so the potential energy function of this system is not quadratic. This thesis presents the application of Gauss's Principle of Least Constraint to the modeling of rolling isolation platforms. The equations of motion are described in terms of a redundant set of constrained coordinates. Coordinate accelerations are uniquely determined at any point in time via Gauss's Principle by solving a linearly constrained quadratic minimization. In the absence of any modeled damping, the equations of motion conserve energy. This mathematical model is then used to find the bowl profile that minimizes response acceleration subject to displacement constraint.
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Moving through a stable, three-dimensional world is a hallmark of our motor and perceptual experience. This stability is constantly being challenged by movements of the eyes and head, inducing retinal blur and retino-spatial misalignments for which the brain must compensate. To do so, the brain must account for eye and head kinematics to transform two-dimensional retinal input into the reference frame necessary for movement or perception. The four studies in this thesis used both computational and psychophysical approaches to investigate several aspects of this reference frame transformation. In the first study, we examined the neural mechanism underlying the visuomotor transformation for smooth pursuit using a feedforward neural network model. After training, the model performed the general, three-dimensional transformation using gain modulation. This gave mechanistic significance to gain modulation observed in cortical pursuit areas while also providing several testable hypotheses for future electrophysiological work. In the second study, we asked how anticipatory pursuit, which is driven by memorized signals, accounts for eye and head geometry using a novel head-roll updating paradigm. We showed that the velocity memory driving anticipatory smooth pursuit relies on retinal signals, but is updated for the current head orientation. In the third study, we asked how forcing retinal motion to undergo a reference frame transformation influences perceptual decision making. We found that simply rolling one's head impairs perceptual decision making in a way captured by stochastic reference frame transformations. In the final study, we asked how torsional shifts of the retinal projection occurring with almost every eye movement influence orientation perception across saccades. We found a pre-saccadic, predictive remapping consistent with maintaining a purely retinal (but spatially inaccurate) orientation perception throughout the movement. Together these studies suggest that, despite their spatial inaccuracy, retinal signals play a surprisingly large role in our seamless visual experience. This work therefore represents a significant advance in our understanding of how the brain performs one of its most fundamental functions.
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This paper presents an FEM analysis conducted for optimally designing end mill cutters through verifying the cutting tool forces and stresses for milling Titanium alloy Ti-6Al-4 V. Initially, the theoretical tool forces are calculated by considering the cutting edge on a cutting tool as the curve of an intersection over a spherical/flat surface based on the model developed by Lee & Altinas [1]. Considering the lowest tool forces the cutting tool parameters are taken and optimal design of end mill is decided for different sizes. Then the 3D CAD models of the end mills are developed and used for Finite Element Method to verify the cutting forces for milling Ti-6Al-4 V. The cutting tool forces, stress, strain concentration (s), tool wear, and temperature of the cutting tool with the different geometric shapes are simulated considering Ti-6Al-4 V as work piece material. Finally, the simulated and theoretical values are compared and the optimal design of cutting tool for different sizes are validated. The present approach considers to improve the quality of machining surface and tool life with effects of the various parameters concerning the oblique cutting process namely axial, radial and tangential forces. Various simulated test cases are presented to highlight the approach on optimally designing end mill cutters.
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Stovepipes, or also called silos, appear in many different organizations and sectors and contribute to problems when employees or managers tend to look more to their own, or the individual departments, objectives rather than to the organizations. The purpose of this study was to identify different communicative factors that promote stovepipes in order to further identify the most critical factor to disarm. A case study has been done at a selected company, with a stovepipe structure, in order to achieve the purpose of the study. The case study has included interviews and observations to identify different problem areas which then have been compared with three communicative factors identified in previous studies. The factor that had the most connections to the problem areas have been considered the most critical factor. The result of the study indicates that “A lack of understanding each other's work” is the most critical factor in stovepipe structures and that it can be prevented by following five recommendations: bring up positive collaboration continually, raise problems with each other instead of with others, identify different communication paths in and between the departments, implement a long-term model for preventing stovepipes and set up workshops between the involved departments. The conclusion of the study is that stovepipes create several undesirable effects in the organization but that the efforts to counter these problems do not have to be complicated. Following five small steps into a better collaboration and communication can be enough to be on your way to a better organizational structure.
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An emergency lowering system for use in safety critical crane applications is discussed. The system is used to safely lower the payload of a crane in case of an electric blackout. The system is based on a backup power source, which is used to operate the crane while the regular supply is not available. The system enables both horizontal and vertical movements of the crane. Two different configurations for building the system are described, one with an uninterruptible power source (UPS) or a diesel generator connected in parallel to the crane’s power supply and one with a customized energy storage connected to the intermediate DC-link in the crane. In order to be able to size the backup power source, the power required during emergency lowering needs to be understood. A simulation model is used to study and optimize the power used during emergency lowering. The simulation model and optimizations are verified in a test hoist. Simulation results are presented with non-optimized and optimized controls for two example applications: a paper roll crane and a steel mill ladle crane. The optimizations are found to significantly reduce the required power for the crane movements during emergency lowering.
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Uppsatsens övergripande syfte är att åskådliggöra hur några gymnasielärare behöriga i svenska som andraspråk respektive svenska betraktar skönlitteraturens roll i ämnet svenska som andraspråk (SVA) och hur det praktiska klassrumsarbetet med litteraturundervisning ser ut. I uppsatsen diskuteras även lärarnas syn på skönlitteraturen i SVA-ämnet i jämförelse med i svenskämnet i relation ämnes- och kursplanerna i Läroplan, examensmål och gymnasiegemensamma ämnen för gymnasieskola 2011. För att uppnå syftet och besvara frågeställningarna har jag genomfört en kvalitativ studie där fyra lärare intervjuats, samtliga verksamma på nationella program. Av resultaten framkommer att lärarna starkt betonar skönlitteraturens betydelse i SVA-undervisningen. De viktigaste motiven för skönlitteraturen som lyfts fram är språkutveckling, identitetsutveckling, främjande av empatisk och demokratisk förmåga samt som förmedlare av svenska referensramar. Vid valen av litterära texter beaktar lärarna styrdokumentens skrivningar samt språkliga faktorer. Två arbetssätt som framhålls är boksamtal och tematiskt arbete. Det litterära samtalet framhävs som positivt för lärandet liksom läsande i en större kontext inom ett gemensamt tema. Lärarna understryker att skillnaderna i styrdokumenten mellan svenskämnena är alltför stora vad avser skrivningar om skönlitteratur och de anser att SVA borde likna svenskämnet mera vad gäller det litterära ämnesinnehållet.
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Svenska elever har presterat dåligt i internationella undersökningar en längre tid när det gäller algebraområdet i matematik. Elevernas begreppsförståelse har pekats ut som en faktor som spelar in i de dåliga resultaten för svenska elever del. Syftet med denna studie har därför varit att ta reda på den roll som begrepp och begreppsförmåga spelar vid inlärning av algebra samt vilken begreppsförståelse elever i årskurs 4-6 har. Genom en systematisk litteraturstudie har frågeställningarna besvarats. Resultaten visar att brister i begreppsförståelse i algebra också leder till brister i kunskap i algebra. Undervisning med fokus på begrepp leder till bättre förståelse för begrepp samtidigt som det även leder till procedurell kunskap. Elever i årskurs 4-6 kan hantera variabler och använda dem i matematiska uttryck. Fördelar med en tidig introduktion av variabelbegreppet är att elever bygger en bättre förståelse för begreppet.
Resumo:
Svenska elever har presterat dåligt i internationella undersökningar en längre tid när det gäller algebraområdet i matematik. Elevernas begreppsförståelse har pekats ut som en faktor som spelar in i de dåliga resultaten för svenska elever del. Syftet med denna studie har därför varit att ta reda på den roll som begrepp och begreppsförmåga spelar vid inlärning av algebra samt vilken begreppsförståelse elever i årskurs 4-6 har. Genom en systematisk litteraturstudie har frågeställningarna besvarats. Resultaten visar att brister i begreppsförståelse i algebra också leder till brister i kunskap i algebra. Undervisning med fokus på begrepp leder till bättre förståelse för begrepp samtidigt som det även leder till procedurell kunskap. Elever i årskurs 4-6 kan hantera variabler och använda dem i matematiska uttryck. Fördelar med en tidig introduktion av variabelbegreppet är att elever bygger en bättre förståelse för begreppet.