900 resultados para Condition-based maintenance
Resumo:
A modelagem 2.5D consiste em simular a propagao do campo de ondas em 3D em meios com simetria de translao em uma direo. Nesta tese esta abordagem formulada para meios elsticos e anisotrpicos com classe de simetria arbitrria e a geometria de aquisio no precisa coincidir com um plano de simetria do meio. A migrao por reverso no tempo do campo de ondas formulada e implementada atravs de diferenas finitas 2.5D. Para reduzir os efeitos de retro-espalhamento e melhorar a recuperao da amplitude dos eventos migrados, propomos uma nova condio de imagem para migrao reversa no tempo baseada na anlise assinttica da condio de imagem clssica por correlao cruzada. Experimentos numricos indicam que a migrao reversa no tempo 2.5D com a nova condio de imagem proposta, melhora a resoluo da imagem em relao migrao reversa no tempo 2D e reduz acentuadamente os rudos causados por retro-espalhamento.
Resumo:
This study aims to recognize the Surface Design as specialty hybrid and clarify the relationship between surface and design through projetual creative act and technical. The study shows that there projetual hybridity in the design of the Surface Design and the same occurs in two distinct stages: the creative phase , where the inherent design specialties together for their training , and executive process in which the diversity of technical information and construction procedures to assist the integration of design with other productive areas . Identify the products presented its projected surface condition , based on concepts checked the state of the art Surface Design was an action that enabled the verification of functional, aesthetic and symbolic object concepts . To evaluate this condition are presented six case studies to verify the levels of cooperation and implementation of the specialties of Design in objects that are highlighted by presenting different surfaces. Among the products are: DKR chair, bench Pai Joo, bench R540, Hbridos table, Facetas table and bench Xique-xique.
Resumo:
We report on three types of skin lesions in a population of blue whales, Balaenoptera musculus, off the northwestern coast of Isla Grande de Chiloe, Chile. These lesions were: (1) cookie-cutter shark, Isistius brasilensis, bites, (2) vesicular or blister lesions, and (3) a tattoo-like skin disease. The presence of these lesions was determined by the examining photos collected in 2006 and 2007 for a blue whale photo-identification project. We examined 289 photographs of 68 individuals for lesions. The cookie-cutter shark lesions are common on these blue whales and similar to those reported from other species of cetaceans. Skin peeling or shedding was observed on some whales and is believed to be a normal condition. Based on the photographs examined to date the vesicular lesions are more common than the tattoo-like lesions. The tattoo-like skin lesions was observed just on a single whale in 2007. The blister lesions were common on whales in both 2006 and 2007. The presence of blister lesions in both years may indicate that this disease will be present in the population for a long time. It is unknown if these lesions contribute to mortality of blue whales frequenting Chilean waters, but the tattoo-like skin lesions if shown to be a pox virus could cause neonatal and calf mortality. Additional investigations are needed that, as a minimum, must include the histological and genetic examination of the two types of disease from live or dead whales, especially the tattoo-like skin lesions. Until this work is undertaken, it will be impossible to determine if these lesions pose a conservation risk to the blue whales off Chile.
Resumo:
Warrick and Hussen developed in the nineties of the last century a method to scale Richards' equation (RE) for similar soils. In this paper, new scaled solutions are added to the method of Warrick and Hussen considering a wider range of soils regardless of their dissimilarity. Gardner-Kozeny hydraulic functions are adopted instead of Brooks-Corey functions used originally by Warrick and Hussen. These functions allow to reduce the dependence of the scaled RE on the soil properties. To evaluate the proposed method (PM), the scaled RE was solved numerically using a finite difference method with a fully implicit scheme. Three cases were considered: constant-head infiltration, constant-flux infiltration, and drainage of an initially uniform wet soil. The results for five texturally different soils ranging from sand to clay (adopted from the literature) showed that the scaled solutions were invariant to a satisfactory degree. However, slight deviations were observed mainly for the sandy soil. Moreover, the scaled solutions deviated when the soil profile was initially wet in the infiltration case or when deeply wet in the drainage condition. Based on the PM, a Philip-type model was also developed to approximate RE solutions for the constant-head infiltration. The model showed a good agreement with the scaled RE for the same range of soils and conditions, however only for Gardner-Kozeny soils. Such a procedure reduces numerical calculations and provides additional opportunities for solving the highly nonlinear RE for unsaturated water flow in soils. (C) 2011 Elsevier B.V. All rights reserved.
Resumo:
This paper deals with the numerical analysis of saturated porous media, taking into account the damage phenomena on the solid skeleton. The porous media is taken into poro-elastic framework, in full-saturated condition, based on Biot's Theory. A scalar damage model is assumed for this analysis. An implicit boundary element method (BEM) formulation, based on time-independent fundamental solutions, is developed and implemented to couple the fluid flow and two-dimensional elastostatic problems. The integration over boundary elements is evaluated using a numerical Gauss procedure. A semi-analytical scheme for the case of triangular domain cells is followed to carry out the relevant domain integrals. The non-linear problem is solved by a Newton-Raphson procedure. Numerical examples are presented, in order to validate the implemented formulation and to illustrate its efficacy. (C) 2011 Elsevier Ltd. All rights reserved.
Resumo:
Lobiettivo del presente lavoro di tesi stato quello di effettuare, tramite lapplicazione di una metodologia RBM Risk Based Maintenance, lanalisi dei guasti avvenuti nel biennio 2012-2013 nel termovalorizzatore di rifiuti solidi urbani di Modena gestito dalla societ Herambiente.
Resumo:
Introduction Current empirical findings indicate that the efficiency of decision making (both for experts and near-experts) in simple situations is reduced under increased stress (Wilson, 2008). Explaining the phenomenon, the Attentional Control Theory (ACT, Eysenck et al., 2007) postulates an impairment of attentional processes resulting in a less efficient processing of visual information. From a practitioners perspective, it would be highly relevant to know whether this phenomenon can also be found in complex sport situations like in the game of football. Consequently, in the present study, decision making of football players was examined under regular vs. increased anxiety conditions. Methods 22 participants (11 experts and 11 near-experts) viewed 24 complex football situations (counterbalanced) in two anxiety conditions from the perspective of the last defender. They had to decide as fast and accurate as possible on the next action of the player in possession (options: shot on goal, dribble or pass to a designated team member) for equal numbers of trials in a near and far distance condition (based on the position of the player in possession). Anxiety was manipulated via a competitive environment, false feedback as well as ego threats. Decision time and accuracy, gaze behaviour (e.g., fixation duration on different locations) as well as state anxiety and mental effort were used as dependent variables and analysed with 2 (expertise) x 2 (distance) x 2 (anxiety) ANOVAs with repeated measures on the last two factors. Besides expertise differences, it was hypothesised that, based on ACT, increased anxiety reduces performance efficiency and impairs gaze behaviour. Results and Discussion Anxiety was manipulated successfully, indicated by higher ratings of state anxiety, F(1, 20) = 13.13, p < .01, p2 = .40. Besides expertise differences in decision making experts responded faster, F(1, 20) = 11.32, p < .01, p2 = .36, and more accurate, F(1,20) = 23.93, p < .01, p2 = .55, than near-experts decision time, F(1, 20) = 9.29, p < .01, p2 = .32, and mental effort, F(1, 20) = 7.33, p = .01, p2 = .27, increased for both groups in the high anxiety condition. This result confirms the ACT assumption that processing efficiency is reduced when being anxious. Replicating earlier findings, a significant expertise by distance interaction could be observed, F(1, 18) = 18.53, p < .01, p2 = .51), with experts fixating longer on the player in possession or the ball in the near distance and longer on other opponents, teammates and free space in the far distance condition. This shows that experts are able to adjust their gaze behaviour to affordances of displayed playing patterns. Additionally, a three way interaction was found, F(1, 18) = 7.37 p = .01, p2 = .29, revealing that experts utilised a reduced number of fixations in the far distance condition when being anxious indicating a reduced ability to pick up visual information. Since especially the visual search behaviour of experts was impaired, the ACT prediction that particularly top-down processes are affected by anxiety could be confirmed. Taken together, the results show that sports performance is negatively influenced by anxiety since longer response times, higher mental effort and inefficient visual search behaviour were observed. From a practitioners perspective, this finding might suggest preferring (implicit) perceptual cognitive training; however, this recommendation needs to be empirically supported in intervention studies. References: Eysenck, M. W., Derakshan, N., Santos, R., & Calvo, M. G. (2007). Anxiety and cognitive performance: Attentional control theory. Emotion, 7, 336-353. Wilson, M. (2008). From processing efficiency to attentional control: A mechanistic account of the anxiety-performance relationship. Int. Review of Sport and Exercise Psychology, 1, 184-201.
Resumo:
Retinal vein occlusion is a leading cause of visual impairment. Experimental models of this condition based on laser photocoagulation of retinal veins have been described and extensively exploited in mammals and larger rodents such as the rat. However, few reports exist on the use of this paradigm in the mouse. The objective of this study was to investigate a model of branch and central retinal vein occlusion in the mouse and characterize in vivo longitudinal retinal morphology alterations using spectral domain optical coherence tomography. Retinal veins were experimentally occluded using laser photocoagulation after intravenous application of Rose Bengal, a photo-activator dye enhancing thrombus formation. Depending on the number of veins occluded, variable amounts of capillary dropout were seen on fluorescein angiography. Vascular endothelial growth factor levels were markedly elevated early and peaked at day one. Retinal thickness measurements with spectral domain optical coherence tomography showed significant swelling (p<0.001) compared to baseline, followed by gradual thinning plateauing two weeks after the experimental intervention (p<0.001). Histological findings at day seven correlated with spectral domain optical coherence tomography imaging. The inner layers were predominantly affected by degeneration with the outer nuclear layer and the photoreceptor outer segments largely preserved. The application of this retinal vein occlusion model in the mouse carries several advantages over its use in other larger species, such as access to a vast range of genetically modified animals. Retinal changes after experimental retinal vein occlusion in this mouse model can be non-invasively quantified by spectral domain optical coherence tomography, and may be used to monitor effects of potential therapeutic interventions.
Resumo:
Obstetric fistula is a devastating child birth injury affecting millions of women worldwide. This paper explores the knowledge and understanding of medical students at the University of Texas Health Science Center at San Antonio regarding this global public health issue. Obstetric fistula has been eradicated in most industrialized nations, and has therefore faded from view of many modern medical organizations. The United Nations Population Fund has launched a Campaign to End Fistula in an attempt to bring global awareness to this preventable and treatable condition. Based on a survey administered to medical students at UTHSCSA, a baseline understanding of this disorder based on current curriculum is reviewed, with the objective of improving future physicians awareness of obstetric fistula. Despite a low survey response rate, there was a significant association between greater knowledge about causes, treatment, and complications of obstetric fistula and advanced years in medical school. However, the fourth year medical students averaged only a 70.5 percent of correct responses on the survey, indicating room for improvement in addressing this topic during medical school. ^
Resumo:
Phase thermodynamics is often perceived as a difficult subject that many students never become fully comfortable with. The Gibbsian geometrical framework can help students to gain a better understanding of phase equilibria. An exercise to interpret the vapor-liquid equilibrium of a binary azeotropic mixture, using the equilibrium condition based on the common tangent plane criterion (the Gibbs stability test), is presented in this paper. From a T-composition phase diagram for the mixture, the temperature is set at different values: above, intermediate to, and below the boiling temperatures of the pure components, to intersect different regions of the system. Students prepare an Excel spreadsheet where the Gibbs energy of mixing of the vapor and liquid mixtures are calculated and represented over the whole range of compositions and then, apply the Gibbs stability test to ascertain the aggregation state of the system and to calculate the VL phase equilibrium compositions. Finally, Matlab is used to generate the 3D Gibbs energy of mixing surfaces for both phases over the whole range of temperatures which facilitates the geometrical interpretation of the vapor-liquid equilibrium.
Resumo:
Loggetto di analisi del presente lavoro di tesi il modello di Operational Excellence noto come World Class Manufacturing in particolare lapproccio allo step 6 del pilastro Professional Maintenance, dove si richiede limplementazione di un sistema di manutenzione PREDITTIVA, la cosiddetta CBM (Conditional Based Maintenance) . Il modello a cui si fa riferimento fu teorizzato dal professore giapponese H. Yamashina verso la met degli anni 2000 e giunse in Italia attorno al 2005, quando Fiat Group (oggi FCA) lo adott come approccio standard alla gestione della produzione. Questo tipo di analisi, orientata verso una prospettiva pratica pi che teorica, deriva direttamente da unesperienza sul campo che ho svolto allinterno di unazienda che ha aderito al World Class Manufacturing (WCM). Nel capitolo 1 verr proposto un excursus delle metodologie alla base del WCM e del percorso storico che ha portato alla formulazione del modello. Nel secondo capitolo verr proposto un caso di applicazione del WCM all'interno di un Gruppo, nella fattispecie Ariston Thermo Group (ATG). Dopo unoverview sul Gruppo e sulla storia della sua adesione al programma di miglioramento, la trattazione si focalizza sull'approccio di ATG al WCM. Nel terzo capitolo verr introdotta la Manutenzione Professionale secondo le principali politiche manutentive schematizzate dal WCM. Verranno presentate singolarmente per sottolineare i loro obiettivi seguiti dai vantaggi e svantaggi che si possono ottenere nellimplementare ogni singola politica. Nel quarto capitolo verranno specificate sotto un aspetto prettamente pratico le varie attivit svolte dalla PM cos da evidenziare lo sviluppo e il miglioramento continuo che essa sta ottenendo dallintroduzione del WCM; principalmente la presentazione delle varie attivit si riferiscono al passaggio allo step 6 della PM, dove verr presentata approfonditamente elencando e analizzando tutte le attivit svolte per approcciarsi alla CBM.
Resumo:
The Social Vulnerability Scale (SVS), an informant-report of social vulnerability for older adults, was piloted in a sample of 167 undergraduate students (63 male, 104 female) from the University of Queensland. Participants aged 18 - 53 (M = 25.53 years, SD = 7.83 years) completed the SVS by rating a relative or friend aged 50 years (M = 71.65 years, SD = 12.49 years): either someone with memory problems, stroke, dementia, or other neurological condition (n = 85); or a healthy older adult (n = 82). Excellent internal consistency and test - retest reliability were demonstrated, and the SVS effectively differentiated healthy older adults from those with a neurological condition based on proxy ratings of social vulnerability. The SVS is a potentially useful adjunct measure of older adults' capacity to reside independently. 1 *For information on using the Social Vulnerability Scale, email d.pinsker@psy.uq.edu.au or stone@psy.uq.edu.au
Resumo:
The Product Service Systems, servitization, and Service Science literature continues to grow as organisations seek to protect and improve their competitive position. The potential of technology applications to deliver service delivery systems facilitated by the ability to make real time decisions based upon in the field performance is also significant. Research identifies four key questions to be addressed. Namely: how far along the servitization continuum should the organisation go in a single strategic step? Does the organisation have the structure and infrastructure to support this transition? What level of condition monitoring should it employ? Is the product positioned correctly in the value chain to adopt condition monitoring technology? Strategy consists of three dimensions, namely content, context, and process. The literature relating to PSS, servitization, and strategy all discuss the concepts relative to content and context but none offer a process to deliver an aligned strategy to deliver a service delivery system enabled by condition based management. This paper presents a tested iterative strategy formulation methodology which is the result of a structured development programme.
Resumo:
Adult anchovies in the Bay of Biscay perform north to south migration from late winter to early summer for spawning. However, what triggers and drives the geographic shift of the population remains unclear and poorly understood. An individual-based fish model has been implemented to explore the potential mechanisms that control anchovy's movement routes toward its spawning habitats. To achieve this goal, two fish movement behaviors gradient detection through restricted area search and kinesis simulated fish response to its dynamic environment. A bioenergetics model was used to represent individual growth and reproduction along the fish trajectory. The environmental forcing (food, temperature) of the model was provided by a coupled physicalbiogeochemical model. We followed a hypothesis-testing strategy to actualize a series of simulations using different cues and computational assumptions. The gradient detection behavior was found as the most suitable mechanism to recreate the observed shift of anchovy distribution under the combined effect of sea-surface temperature and zooplankton. In addition, our results suggested that southward movement occurred more actively from early April to middle May following favorably the spatio-temporal evolution of zooplankton and temperature. In terms of fish bioenergetics, individuals who ended up in the southern part of the bay presented better condition based on energy content, proposing the resulting energy gain as an ecological explanation for this migration. The kinesis approach resulted in a moderate performance, producing distribution pattern with the highest spread. Finally, model performance was not significantly affected by changes on the starting date, initial fish distribution and number of particles used in the simulations, whereas it was drastically influenced by the adopted cues.
Resumo:
Safety is one of the major concerns of process safety engineers in most industrial facilities all over the world. To this scope, some events play an important role once the effect of their consequences can be assumed as totally undesirable. One of these events refers to the occurrence of a fire. Such event can result in catastrophic consequences for life, equipment, and continuity of activities or even leading to environmental damage. A fire protection equipment with low reliability means that this equipment are often unavailable and thus the risk of a fire increases. Maintenance of fire protection equipment is very important because this kind of systems is mostly in a dormant mode, which gives uncertainty about their operability when demanded in a real situation of fire. This article outlines the importance of tests, inspection, and maintenance operations in the context of a fire sprinkler system and proposes a methodology based on international standards and supported by test/inspection reports to correct the frequency of these actions according to the level of degradation of the components and regarding safety purposes. 2015 American Institute of Chemical Engineers.