Residual Service Life Prognostic Models for Tapered Roller Bearings

There are a few different bearing health monitoring technologies currently used in the railroad industry, both reactive and preventative detection systems. Reactive models have proven to be ineffective in monitoring bearing health, which has resulted in either unnecessary train stoppages and delays or in-service failures and bearing burn-off leading to catastrophic train derailments. Wayside preventative detection systems, while more effective than reactive technologies, are scarce and neglect railcars’ that do not travel over a specific route. This knowledge prompted the University Transportation Center for Railway Safety at UTRGV to develop an onboard bearing health monitoring system that can accurately assess the health of a bearing and identify the defective component at an early stage of the defect development. This system has been proven to accurately detect defective bearings through extensive laboratory testing validated by field testing performed at the Transportation Technology Center, Inc. in Pueblo, CO. Using this system, a prognostic model for the residual service life of a defective bearing was developed. This model can be used by the railroads to schedule proactive maintenance cycles to mitigate inefficient faulty bearing replacements

Fiabilidade do modelo Lok no diagnóstico da cirrose hepática

Trabalho final de mestrado integrado em Medicina área cientifica de Gastroenterologia, apresentado à Faculdade de Medicina da Universidade de CoimbraIntrodução: Marcadores serológicos que permitem avaliar a presença de cirrose hepática têm sido intensamente estudados. Contudo, a biópsia hepática continua a ser o Gold-standard para avaliar o grau de fibrose. O modelo de Lok é um teste indirecto que consiste numa fórmula que analisa marcadores indirectos de fibrose e foi formulado para permitir detectar cirrose em doentes com hepatite C crónica. Objectivos: Estudar a fiabilidade do modelo de Lok no diagnóstico de cirrose hepática em doentes com hepatopatia crónica terminal de etiologia não colestática. Determinar qual o marcador indirecto com maior associação com a existência de cirrose. Metodologia: Estudo retrospectivo de dados laboratoriais e histopatológicos de explantes obtidos de doentes com hepatopatia crónica terminal. Foram avaliados os valores de alanina e aspartato-aminotranferases (ALT e AST), plaquetas, índice internacional normalizado (INR), bilirrubina total, albumina, creatinina, γ-glutamiltransferase (γ-GT) e fosfastase alcalina. Os casos com diagnóstico de cirrose no explante foram retidos para estudo. Excluíram-se doentes com patologia colestática. A partir do modelo de Lok, determinou-se a existência de cirrose na amostra e analisou-se a correlação entre os marcadores bioquímicos e a probabilidade de diagnóstico de cirrose. Resultados: A amostra foi constituída por 100 doentes, dos quais 82% do sexo masculino. A média da idade foi de 47 ± 10,46 anos. Não houve correlação da AST, albumina e fosfatase alcalina com a probabilidade de cirrose pelo método de Lok. Quanto a AST, a razão AST/ALT, a bilirrubina, o INR, as plaquetas e a γ-GT, observou-se haver correlação com a probabilidade de diagnóstico de cirrose. O modelo de Lok detectou cirrose em 98% dos doentes. A probabilidade de diagnóstico de cirrose na biópsia pelo teste de Lok nesta amostra foi de 93,77%. Conclusão: Entre os parâmetros bioquímicos avaliados o INR apresentou maior correlação com a probabilidade de cirrose (p <0.05). O modelo de Lok foi fiável na detecção de cirrose quando aplicado numa população com hepatopatia crónica terminal de causa não colestática.Introduction: Serological markers for assessing the presence of liver cirrhosis have been intensively studied. However, liver biopsy (LB) remains the gold standard for assessing the degree of fibrosis. Lok’s model is an indirect test that consists in a formula that analyzes indirect markers of fibrosis and has been formulated for detecting cirrhosis in patients with chronic hepatitis C. Objectives: Study the reliability of the Lok’s model in the diagnosis of liver cirrhosis in patients with terminal chronic liver disease except in cholestatic etiology. Determine the indirect marker with the highest association with the presence of cirrhosis. Methodology: Retrospective analysis of laboratory and histopathological data of explants obtained from patients with terminal chronic liver disease. The values of alanine and aspartate aminotransferase (ALT and AST), platelet count, International Normalized Ratio (INR), total bilirubin, albumin, creatinine, γ-glutamyltransferase (γ-GT) and alkaline fosfastase were evaluated. Cases with diagnosis of cirrhosis of the explant were retained for study. We excluded patients with cholestatic disease. From Lok’s model, we determined the existence of cirrhosis in the population and analyzed the correlation between biochemical markers and the probability of diagnosis of cirrhosis. Results: Population consisted of 100 patients, of whom 82% were male. The average age was 47 ± 10.46 years. There was no correlation of AST, albumin and alkaline phosphatase with the probability of cirrhosis by the method of Lok. The ration AST/ALT, value of AST, bilirubin, INR, platelets, and γ-GT, there was no correlation with the probability of cirrhosis. The Lok model detected cirrhosis in 98% of patients. In our population, the probability of diagnosis of cirrhosis in the biopsy with Lok’s test was 93.77%. Conclusion: Among the biochemical parameters evaluated, INR showed a higher correlation with the probability of cirrhosis (p <0.05). Lok’s model was reliable in the detection of cirrhosis when applied in a population with chronic terminal liver disease not cholestatic

Estimating the Inner Ring Defect Size and Residual Service Life of Freight Railcar Bearings Using Vibration Signatures

There are currently two primary wayside detection systems for monitoring the health of freight railcar bearings in the railroad industry: The Trackside Acoustic Detection System (TADS™) and the wayside Hot-Box Detector (HBD). TADS™ uses wayside microphones to detect and alert the train operator of high-risk defects. However, many defective bearings may never be detected by TADS™ since a high-risk defect is a spall which spans about 90% of a bearing’s raceway, and there are less than 30 systems in operation throughout the United States and Canada. HBDs sit on the side of the rail-tracks and use non-contact infrared sensors to acquire temperatures of bearings as they roll over the detector. These wayside bearing detection systems are reactive in nature and often require emergency stops in order to replace the wheelset containing the identified defective bearing. Train stoppages are inefficient and can be very costly. Unnecessary train stoppages can be avoided if a proper maintenance schedule can be developed at the onset of a defect initiating within the bearing. Using a proactive approach, railcars with defective bearings could be allowed to remain in service operation safely until reaching scheduled maintenance. The University Transportation Center for Railway Safety (UTCRS) research group at the University of Texas Rio Grande Valley (UTRGV) has been working on developing a proactive bearing condition monitoring system which can reliably detect the onset of bearing failure. Unlike wayside detection systems, the onboard condition monitoring system can continuously assess the railcar bearing health and can provide accurate temperature and vibration profiles to alert of defect initiation. This system has been validated through rigorous laboratory testing at UTRGV and field testing at the Transportation Technology Center, Inc. (TTCI) in Pueblo, CO. The work presented here builds on previously published work that demonstrates the use of the onboard condition monitoring system to identify defective bearings as well as the correlations developed for spall growth rates of defective bearing outer rings (cups). The system first uses the root-mean-square (RMS) value of the bearing’s acceleration to assess its health. Then, an analysis of the frequency domain of the acquired vibration signature determines if the bearing has a defective inner ring (cone) and the RMS value is used to estimate the defect size. This estimated size is then used to predict the residual life of the bearing. The methodology proposed in this paper can assist railroads and railcar owners in the development of a proactive and cost-efficient maintenance cycle for their rolling stock

Ambipolar Diffusion-Mediated Thermal Fronts in the Neutral ISM

In a thermally bistable medium, cold, dense gas is separated from warm, rareified gas by thin phase transition layers, or fronts, in which heating, radiative cooling, thermal conduction, and convection of material are balanced. We calculate the steady-state structure of such fronts in the presence of magnetic fields, including the processes of ion-neutral drift and ion-neutral frictional heating. We find that ambipolar diffusion efficiently transports the magnetic field across the fronts, leading to a flat magnetic field strength profile. The thermal profiles of such fronts are not significantly different from those of unmagnetized fronts. The near uniformity of the magnetic field strength across a front is consistent with the flat field strength-gas density relation that is observed in diffuse interstellar gas.Comment: 17 pages, 12 figures, 1 table, accepted for publication in Ap

Nanopartículas como sistemas de veiculação de fármacos para a via ocular

Trabalho Final de Mestrado Integrado, Ciências Farmacêuticas, 2020, Universidade de Lisboa, Faculdade de Farmácia.A administração ocular de fármacos constitui, ainda nos dias de hoje, um desafio devido à complexa arquitetura do olho. Atualmente, grande parte das formulações comercializadas apresentam-se sob a forma de colírio, não só devido à sua simplicidade de utilização e pela elevada adesão por parte do doente, mas também pelo facto de se tratar de uma solução terapêutica não invasiva. No entanto, a biodisponibilidade ocular dos fármacos administrados topicamente é limitada, tanto pelas propriedades físico-químicas pouco favoráveis das substâncias ativas, como pelos diversos mecanismos de proteção do olho, que são responsáveis por impedir a entrada de xenobióticos. Se por um lado, os tratamentos tópicos convencionais não conseguem entregar o fármaco no local de ação pretendido, por outro, as injeções intravítreas entregam o fármaco diretamente na cavidade vítrea. Contudo, injeções frequentes podem provocar efeitos adversos como por exemplo, descolamento da retina, endoftalmite e hemorragia na retina. Deste modo, torna-se urgente continuar a investigar formas para melhorar a penetração na estrutura ocular, aumentar a biodisponibilidade do fármaco e prolongar o tempo de retenção na superfície ocular. Nos últimos anos, novos sistemas de veiculação de fármacos foram propostos para contornar os principais problemas das formulações oftálmicas convencionais. As nanopartículas surgiram como transportadores promissores, dando origem a colírios e soluções injetáveis “modificados” com o objetivo de melhorar a eficácia do medicamento, sem comprometer a sua segurança e a adesão do doente. Esta revisão aborda não só os diferentes fatores envolvidos no desenvolvimento de nanopartículas como sistemas veiculadores de fármacos, com especial ênfase nas nanopartículas poliméricas, lipídicas e nas de ouro, como também os desafios regulamentares implicados no desenvolvimento das nanopartículas. Por fim, são apresentadas algumas orientações adicionais publicadas pela Agência Europeia do Medicamento, de forma a ultrapassar determinadas questões regulamentares devido à natureza multidisciplinar dos sistemas nanoparticulados com aplicações no campo terapêutico de determinadas patologias oculares.Ocular drug administration still remains a challenge nowadays due to the complex architecture of the eye. Currently, most of the commercialized formulations are presented in the form of eye drops, not only due to their simplicity of use and the high compliance by the patient, but also because it is a non-invasive therapeutic solution. However, the ocular bioavailability of topically administered drugs is limited, both by the unfavorable physicochemical properties of the active substances, and by the various protective mechanisms of the eye, which are responsible for preventing the entry of xenobiotics. If, on the one hand, conventional topical treatments fail to deliver the drug to the intended site of action, on the other, intravitreal injections deliver the drug directly to the vitreous cavity. However, frequent injections can cause adverse effects such as retinal detachment, endophthalmitis and retinal hemorrhage. Thus, there is an urgent need to continue investigating ways to improve penetration into the ocular structure, increase bioavailability and prolong the retention time on the ocular surface. In recent years, new drug delivery systems have been proposed to overcome the main problems of conventional ophthalmic formulations. Nanoparticles have emerged as promising carriers, giving rise to “modified” eye drops and injectable solutions with the aim of improving the effectiveness of the drug, without compromising its safety and patient compliance. This review addresses not only the different factors involved in the development of nanoparticles as drug delivery systems, with a special emphasis on polymeric, lipidic and gold nanoparticles, but also the regulatory challenges involved in the development of nanoparticles. Finally, some additional guidelines published by the European Medicines Agency are presented in order to overcome certain regulatory issues due to the multidisciplinary nature of nanoparticulate systems with applications in the therapeutic field of certain ocular pathologies

Prognostics Models for Railroad Tapered Roller Bearings with Spall Defects on Inner or Outer Rings

Rolling contact fatigue (RCF) is one of the major causes of failure in railroad bearings used in freight service. Subsurface inclusions resulting from impurities in the steel used to fabricate the bearings initiate subsurface fatigue cracks, which propagate upwards and cause spalling of the rolling surfaces. These spalls start small and propagate as continued operation induces additional crack formation and spalling. Studies have shown that the bearing temperature is not a good indicator of spall initiation. In many instances, the temperature of the bearing increases markedly only when the spall has spread across major portions of the raceway. In contrast, vibration signatures can be used to accurately detect spall initiation within a bearing and can track spall deterioration. No monitoring technique can indicate the growth rate of a spall or determine residual useful life. Hence, the main objective of this study is to develop reliable prognostic models for spall growth within railroad bearings that are based on actual service life testing rather than theoretical simulations. The data used to devise the models presented here were acquired from laboratory and field testing that started in 2010. Growth models are provided for spalls initiating on the bearing inner (cone) and outer (cup) rings. Coupling these prognostic models with a previously developed vibration-based bearing condition monitoring algorithm will provide the rail industry with an efficient tool that can be used to plan proactive maintenance schedules that will mitigate unnecessary and costly train stoppages and delays and will prevent catastrophic derailments

De muitas verdades a uma: histórias enredadas, memórias tuteladas e a Comissão Nacional da Verdade (1979-2014)

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Filosofia e Ciências Humanas, Programa de Pós-Graduação em História, Florianópolis, 2017.A Comissão Nacional da Verdade do Brasil (CNV) chama atenção por seu caráter tardio em relação às demais comissões latino-americanas e levanta questões que se delineiam na zona de tensão que diz respeito ao entrecruzamento da construção de memórias públicas com a ritualização da justiça, apontando para uma modalidade específica de reparação característica da problemática dos direitos humanos. Este trabalho procura problematizar a emergência da CNV enquanto processo de institucionalização das memórias públicas em torno às violências praticadas por agentes do estado, sobretudo durante a ditadura civil-militar. Assim, interrogar seus limites, seus viéses e sua dimensão de governo das memórias públicas de sujeitos/as vitimizados/as por esse regime. Visa também a propor questões referentes a possíveis alcances de um tipo de aparelho estatal no que concerne o reconhecimento de perspectivas previamente obliteradas da história e ao impacto que este pode vir a ter no campo dos direitos humanos no Brasil, bem como a investigar sua inserção em um contexto e trajetória mais amplos de estratégias de administração do passado e produção de história. Finalmente, me proponho a analisar a forma como se constroem os/as sujeitos/as dos direitos humanos narrados/as pelo informe segundo alguns marcadores sociais da diferença, contraponto contra-narrativas a esse relato unificador e medindo silêncios.Abstract : The National Truth Commission of Brazil (Comissão Nacional da Verdade ? CNV) stands out for its late emergence in relation to other Latin American commissions, and raises questions that are outlined in the tension zone laid out on the crossroads between the construction of public memories and the ritualisation of justice, pointing towards a specific modality of reparation that characterises the problematic field of human rights. This work aims at raising issues about the emergency of CNV as a process of institutionalisation of public memories surrounding the violence practiced by state agents, especially during the civil-military dictatorship. Thus, at interrogating its limits, its biases, and its dimension of government of public memories of subjects victimised by this regime. It also intends to raise questions about the possible reaches of this kind of state apparatus concerning the recognition of previously obliterated perspectives of history and the impact that it may come to have in the human rights sphere in Brazil, as well as to investigate its insertion in a wider context and longer trajectory of administration of the past and production of history. Finally, I propose myself to analyse the way through which the subjects of human rights narrated by the report are built according to social markers of difference, contrasting counter-narratives to this unifying account and measuring silences

Implicações teóricas sobre o miniconto como vazio e quebra da good continuation

The current study demonstrates how the blanks and the disturbance of good continuation characterize a “minimalist literature”, which is called mini short stories by some authors. Therefore, the Theory of Aesthetic Effect and Literary Anthropology – by the German literary theorist Wolfgang Iser (1999a, 1999b), the thesis of Santos (2009), Spalding’s (2008) and Alonso’s (2015) dissertations, are used as theoretical foundation. In order to achieve the proposed objective, seven mini short stories will be taken as the object of analysis: four of them are contained in the book The hundred smallest tales of the century, organized by Marcelino Freire (2004), two of them are part of the work 111 ais, by Dalton Trevisan (2000), and one mini short story is from the book To save the Birds, by Luiz Felipe Leprevost.O presente trabalho demonstra como o vazio e a quebra da good continuation caracterizam uma “literatura minimalista”, a qual é denominada por alguns de miniconto. Para isso, utiliza-se como fundamentação teórica a Teoria do Efeito Estético e a Antropologia Literária do teórico literário alemão Wolfgang Iser (1999a, 1999b), a tese de Santos (2009) e as dissertações de Spalding (2008) e Alonso (2015). Para a consecução do objetivo aqui proposto, tomar-se-á como objeto de análise sete minicontos: quatro deles contidos no livro Os cem menores contos do século, organizado por Marcelino Freire (2004), dois na criação 111 ais, de Dalton Trevisan (2000) e um miniconto do livro Salvar os pássaros, de Luiz Felipe Leprevost

Estimating the Outer Ring Defect Size and Remaining Service Life of Freight Railcar Bearings Using Vibration Signatures

The railroad industry currently utilizes two wayside detection systems to monitor the health of freight railcar bearings in service: The Trackside Acoustic Detection System (TADS™) and the wayside Hot-Box Detector (HBD). TADS™ uses wayside microphones to detect and alert the conductor of high-risk defects. Many defective bearings may never be detected by TADS™ since a high-risk defect is a spall which spans more than 90% of a bearing’s raceway, and there are less than 20 systems in operation throughout the United States and Canada. Much like the TADS™, the HBD is a device that sits on the side of the rail-tracks and uses a non-contact infrared sensor to determine the temperature of the train bearings as they roll over the detector. These wayside detectors are reactive in the detection of a defective bearing and require emergency stops in order to replace the wheelset containing the defective bearing. These costly and inefficient train stoppages can be prevented if a proper maintenance schedule can be developed at the onset of a defect initiating within the bearing. This proactive approach would allow for railcars with defective bearings to remain in service operation safely until reaching scheduled maintenance. Driven by the need for a proactive bearing condition monitoring system in the rail industry, the University Transportation Center for Railway Safety (UTCRS) research group at the University of Texas Rio Grande Valley (UTRGV) has been developing an advanced onboard condition monitoring system that can accurately and reliably detect the onset of bearing failure using temperature and vibration signatures of a bearing. This system has been validated through rigorous laboratory testing at UTRGV and field testing at the Transportation Technology Center, Inc. (TTCI) in Pueblo, CO. The work presented here builds on previously published work that demonstrates the use of the advanced onboard condition monitoring system to identify defective bearings as well as the correlations developed for spall growth rates of defective bearing outer rings (cups). Hence, the system uses the root-mean-square (RMS) value of the bearing’s acceleration to assess its health. Once the bearing is determined to have a defective outer ring, the RMS value is then used to estimate the defect size. This estimated size is then used to predict the remaining service life of the bearing. The methodology proposed in this paper can prove to be a useful tool in the development of a proactive and cost-efficient maintenance cycle for railcar owners