Low-cost vibration sensors: tendencies and applications in condition monitoring of machines and structures

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Mecânica

Design of New Materials for Passive Vibration Control

The objective of this contribution is to extend the models of cellular/composite material design to nonlinear material behaviour and apply them for design of materials for passive vibration control. As a first step a computational tool allowing determination of optimised one-dimensional isolator behaviour was developed. This model can serve as a representation for idealised macroscopic behaviour. Optimal isolator behaviour to a given set of loads is obtained by generic probabilistic metaalgorithm, simulated annealing. Cost functional involves minimization of maximum response amplitude in a set of predefined time intervals and maximization of total energy absorbed in the first loop. Dependence of the global optimum on several combinations of leading parameters of the simulated annealing procedure, like neighbourhood definition and annealing schedule, is also studied and analyzed. Obtained results facilitate the design of elastomeric cellular materials with improved behaviour in terms of dynamic stiffness for passive vibration control.

Ground Vibrations Induced by High-Speed Trains in Regions with Sudden Foundation Stiffness Change

In this paper analytical transient solutions of dynamic response of one-dimensional systems with sudden change of foundation stiffness are derived. In more details, cantilever dynamic response, expressed in terms of vertical displacement, is extended to account for elastic foundation and then two cantilever solutions, corresponding to beams clamped on left and right hand side, with different value of Winkler constant are connected together by continuity conditions. The internal forces, as the unknowns, can be introduced by the same values in both clamped beam solutions and solved. Assumption about time variation of internal forces at the section of discontinuity must be adopted and originally analytical solution will have to include numerical procedure.

The Influence of Damping on Vibration Induced by High-Speed Trains

Passage of high-speed trains may induce high ground and track vibrations, which, besides increasing wheel, rail and track deterioration, may have a negative impact on the vehicle stability and on the passengers comfort. In this paper two distinct analyses are presented. The first one is dedicated to efficient decoupling of rail and soil vibrations by suggesting new interface materials in rail-sleeper fixing system, i.e. in the part where damping efficiency can be directly controlled and tested. The second analysis concerns with an adequate model of soils damping. Proper understanding and correct numerical simulation of this behaviour can help in suggesting soil improvement techniques.

Possible risk factors for vertical transmission of Chagas' disease

The author emphasizes the importance of the congenital transmission of Chagas' disease and discusses the possible risk factors for transmission such as age, origin, obstetrical history and maternal form of disease. Exacerbation of infection during pregnancy is also considered as a possible risk factor for transmission. Besides, a relationship between the frequency of transmission and gestational age is presented. Concerning breast-feeding, the risk of transmission is directly related to the acute phase of maternal disease and bleeding nipples. The deleterious effects of chagasic infection on the fetus and newborn are also considered.

Sistema de Variação de Lastro para Controlo de Movimento Vertical de Veículo Subaquático

O principal motivo para a realização deste trabalho consistiu no desenvolvimento de tecnologia robótica, que permitisse o mergulho e ascenção de grandes profundidades de uma forma eficiente. O trabalho realizado contemplou uma fase inicial de análise e estudo dos sistemas robóticos existentes no mercado, bem como métodos utilizados identificando vantagens e desvantagens em relação ao tipo de veículo pretendido. Seguiu-se uma fase de projeto e estudo mecânico, com o intuito de desenvolver um veículo com variação de lastro através do bombeamento de óleo para um reservatório exterior, para variar o volume total do veículo, variando assim a sua flutuabilidade. Para operar a grande profundidade com AUV’s é conveniente poder efetuar o trajeto up/down de forma eficiente e a variação de lastro apresenta vantagens nesse aspeto. No entanto, contrariamente aos gliders o interesse está na possibilidade de subir e descer na vertical. Para controlar a flutuabilidade e ao mesmo tempo analisar a profundidade do veículo em tempo real, foi necessario o uso de um sistema de processamento central que adquirisse a informação do sensor de pressão e comunicasse com o sistema de variação de lastro, de modo a fazer o controlo de posicionamento vertical desejado. Do ponto de vista tecnológico procurou-se desenvolver e avaliar soluções de variação de volume intermédias entre as dos gliders (poucas gramas) e as dos ROV’s workclass (dezenas ou centenas de kilogramas). Posteriormente, foi desenvolvido um simulador em matlab (Simulink) que reflete o comportamento da descida do veículo, permitindo alterar parâmetros do veículo e analisar os seus resultados práticos, de modo a poder ajustar o veículo real. Nos resultados simulados verificamos o cálculo das velocidades limite atingidas pelo veículo com diferentes coeficientes de atrito, bem como o comportamento da variação de lastro do veículo no seu deslocamento vertical. Sistema de Variação de Lastro para Controlo de Movimento Vertical de Veículo Subaquático Por fim, verificou-se ainda a capacidade de controlo do veículo para uma determinada profundiade, e foi feita a comparação entre estas simulações executadas com parâmetros muito próximos do ensaio real e os respetivos ensaios reais.

Vibration control with shape-memory alloys in civil engineering structures

Dissertação apresentada à Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Doutor em Engenharia Civil

VERTICAL TRANSMISSION OF HTLV-I/II: A review

The vertical transmission of the human T-cell lymphotropic virus type I (HTLV-I) occurs predominantly through breast-feeding. Since some bottle-fed children born to carrier mothers still remain seropositive with a frequency that varies from 3.3% to 12.8%, an alternative pathway of vertical transmission must be considered. The prevalence rate of vertical transmission observed in Japan varied from 15% to 25% in different surveys. In Brazil there is no evaluation of this form of transmission until now. However, it is known that in Salvador, Bahia, 0.7% to 0.88% of pregnant women of low socio-economic class are HTLV-I carriers. Furthermore the occurrence of many cases of adult T-cell leukemia/lymphoma and of four cases of infective dermatitis in Salvador, diseases directly linked to the vertical transmission of HTLV-I, indicates the importance of this route of infection among us. Through prenatal screening for HTLV-I and the refraining from breast-feeding a reduction of ~ 80% of vertical transmission has been observed in Japan. We suggest that in Brazil serologic screening for HTLV-I infection must be done for selected groups in the prenatal care: pregnant women from endemic areas, Japanese immigrants or Japanese descendents, intravenous drug users (IDU) or women whose partners are IDU, human immunodeficiency virus carriers, pregnant women with promiscuous sexual behavior and pregnant women that have received blood transfusions in areas where blood donors screening is not performed. There are in the literature few reports demonstrating the vertical transmission of HTLV-II.

O financiamento por capitação ajustada pelo risco em contexto de integração vertical de cuidados de saúde : a utilização dos consumos com medicamentos como proxy da carga de doença em ambulatório

RESUMO - Introdução - Com o presente projecto de investigação pretendeu-se estudar o financiamento por capitação ajustado pelo risco em contexto de integração vertical de cuidados de saúde, recorrendo particularmente a informação sobre o consumo de medicamentos em ambulatório como proxy da carga de doença. No nosso país, factores como a expansão de estruturas de oferta verticalmente integradas, inadequação histórica da sua forma de pagamento e a recente possibilidade de dispor de informação sobre o consumo de medicamentos de ambulatório em bases de dados informatizadas são três fortes motivos para o desenvolvimento de conhecimento associado a esta temática. Metodologia - Este trabalho compreende duas fases principais: i) a adaptação e aplicação de um modelo de consumo de medicamentos que permite estimar a carga de doença em ambulatório (designado de PRx). Nesta fase foi necessário realizar um trabalho de selecção, estruturação e classificação do modelo. A sua aplicação envolveu a utilização de bases de dados informatizadas de consumos com medicamentos nos anos de 2007 e 2008 para a região de Saúde do Alentejo; ii) na segunda fase foram simulados três modelos de financiamento alternativos que foram propostos para financiar as ULS em Portugal. Particularmente foram analisadas as dimensões e variáveis de ajustamento pelo risco (índices de mortalidade, morbilidade e custos per capita), sua ponderação relativa e consequente impacto financeiro. Resultados - Com o desenvolvimento do modelo PRx estima-se que 36% dos residentes na região Alentejo têm pelo menos uma doença crónica, sendo a capacidade de estimação do modelo no que respeita aos consumos de medicamentos na ordem dos 0,45 (R2). Este modelo revelou constituir uma alternativa a fontes de informação tradicionais como são os casos de outros estudos internacionais ou o Inquérito Nacional de Saúde. A consideração dos valores do PRx para efeitos de financiamento per capita introduz alterações face a outros modelos propostos neste âmbito. Após a análise dos montantes de financiamento entre os cenários alternativos, obtendo os modelos 1 e 2 níveis de concordância por percentil mais próximos entre si comparativamente ao modelo 3, seleccionou-se o modelo 1 como o mais adequado para a nossa realidade. Conclusão - A aplicação do modelo PRx numa região de saúde permitiu concluir em função dos resultados alcançados, que já existe a possibilidade de estruturação e operacionalização de um modelo que permite estimar a carga de doença em ambulatório a partir de informação relativa ao seu perfil de consumo de medicamentos dos utentes. A utilização desta informação para efeitos de financiamento de organizações de saúde verticalmente integradas provoca uma variação no seu actual nível de financiamento. Entendendo este estudo como um ponto de partida onde apenas uma parte da presente temática ficará definida, outras questões estruturantes do actual sistema de financiamento não deverão também ser olvidadas neste contexto. ------- ABSTRACT - Introduction - The main goal of this study was the development of a risk adjustment model for financing integrated delivery systems (IDS) in Portugal. The recent improvement of patient records, mainly at primary care level, the historical inadequacy of payment models and the increasing number of IDS were three important factors that drove us to develop new approaches for risk adjustment in our country. Methods - The work was divided in two steps: the development of a pharmacy-based model in Portugal and the proposal of a risk adjustment model for financing IDS. In the first step an expert panel was specially formed to classify more than 33.000 codes included in Portuguese pharmacy national codes into 33 chronic conditions. The study included population of Alentejo Region in Portugal (N=441.550 patients) during 2007 and 2008. Using pharmacy data extracted from three databases: prescription, private pharmacies and hospital ambulatory pharmacies we estimated a regression model including Potential Years of Life Lost, Complexity, Severity and PRx information as dependent variables to assess total cost as the independent variable. This healthcare financing model was compared with other two models proposed for IDS. Results - The more prevalent chronic conditions are cardiovascular (34%), psychiatric disorders (10%) and diabetes (10%). These results are also consistent with the National Health Survey. Apparently the model presents some limitations in identifying patients with rheumatic conditions, since it underestimates prevalence and future drug expenditure. We obtained a R2 value of 0,45, which constitutes a good value comparing with the state of the art. After testing three scenarios we propose a model for financing IDS in Portugal. Conclusion - Drug information is a good alternative to diagnosis in determining morbidity level in a population basis through ambulatory care data. This model offers potential benefits to estimate chronic conditions and future drug costs in the Portuguese healthcare system. This information could be important to resource allocation decision process, especially concerning risk adjustment and healthcare financing.

Chagasic megaesophagus and megacolon diagnosed in childhood and probably caused by vertical transmission

Reports on children presenting symptoms compatible with the chronic phase of Chagas disease are sporadic. We report a case of a 7-year-old boy who had megaesophagus and megacolon, both of them a consequence of the trypanosomiasis. The etiology was established by means of laboratory and histological features. Based on epidemiological data, the authors concluded that vertical transmission was the most probable route of acquisition. This diagnosis should be considered in children presenting similar complaints, even those living away from endemic areas.

No evidence of vertical transmission of HTLV-I in bottle-fed children

The most frequent pathway of vertical transmission of HTLV-I is breast-feeding, however bottle fed children may also become infected in a frequency varying from 4 to 14%. In these children the most probable routes of infection are transplacental or contamination in the birth canal. Forty-one bottle-fed children of HTLV-I seropositive mothers in ages varying from three to 39 months (average age of 11 months) were submitted to nested polymerase chain reaction analysis (pol and tax genes). 81.5% of the children were born by an elective cesarean section. No case of infection was detected. The absence of HTLV-I infection in these cases indicates that transmission by transplacental route may be very infrequent.

Design of New Materials for Passive Vibration Control

The aim of this contribution is to extend the techniques of composite materials design to non-linear material behaviour and apply it for design of new materials for passive vibration control. As a first step a computational tool allowing determination of macroscopic optimized one-dimensional isolator behaviour was developed. Voigt, Maxwell, standard and more complex material models can be implemented. Objective function considers minimization of the initial reaction and/or displacement peak as well as minimization of the steady-state amplitude of reaction and/or displacement. The complex stiffness approach is used to formulate the governing equations in an efficient way. Material stiffness parameters are assumed as non-linear functions of the displacement. The numerical solution is performed in the complex space. The steady-state solution in the complex space is obtained by an iterative process based on the shooting method which imposes the conditions of periodicity with respect to the known value of the period. Extension of the shooting method to the complex space is presented and verified. Non-linear behaviour of material parameters is then optimized by generic probabilistic meta-algorithm, simulated annealing. Dependence of the global optimum on several combinations of leading parameters of the simulated annealing procedure, like neighbourhood definition and annealing schedule, is also studied and analyzed. Procedure is programmed in MATLAB environment.

Avaliação da Imunidade para Infecções de Transmissão Vertical na População de Mulheres da Maternidade

Introdução: O rastreio sistemático para infecções de transmissão vertical durante a gravidez permite melhorar o prognóstico e o seguimento dos doentes eventualmente afectados e facilita o raciocínio do pediatra ou neonatologista. Objectivo: Avaliar a imunidade materna e a evolução nos últimos anos e a estudar a influência da idade e da nacionalidade no estado imunológico para estas doenças. Métodos e doentes: Estudo não probabilístico de prevalência de imunidade e infecção durante a gravidez. Dados obtidos dos processos clínicos dos recém-nascidos da Maternidade do Hospital (Abril, 2004-Diciembro, 2009). Resultados: Em 3162 mulheres recolheram-se 9508 resultados de serología 2639 resultados de rastreio para Streptococcus do grupo B (SGB). A taxa de imunidade para rubéola foi 93,3%, significativamente mais elevada em mães portuguesas e também mais elevada que no período 1988-95; para a toxoplasmosis foi 25,7%, superior nos grupos de mães com mais idade e entre estrangeiras e mais baixa que no período 1988-95; foi encontrada IgG positiva para virus citomegálico humano (CMV) em 62,4% das mulheres. No período 1988-95 era de 85%. As provas não treponémicas foram positivas em 0,5%. O AgHBs foi identificado em 2,3%, com taxa mais elevada entre as estrangeiras. Os anticorpos para o vírus da hepatite C e para o vírus da imunodeficiência humana foram encontrados respectivamente em 1,4% e 2,8% das mulheres rastreadas. Não forma diagnosticados casos de infecção congénita. A taxa de seroconversão para a Toxoplasmose diminuiu de 1988 para o período em estudo. O rastreio para o SGB revelou que 13,9% das mulheres eram portadoras. Conclusão: Em vinte e cinco anos foi possível identificar uma mudança importante na seroprevalência e taxa de seroconversão de algumas doenças infecciosas de transmissão vertical durante a gravidez.

Perinatal Bacterial Infection: Screenning of Vertical Transmitted Infections

Perinatal bacterial infection may be caused by any microorganism colonizing the vaginal tract. Neonatologists and paediatricians are especially concerned about group B Stretpococcus (GBS). However, Enterobactereacea, mainly E.coli and Proteus, are also responsible for infection. GBS screening may be accomplished in over 90% of pregnant women. In our maternity in 2007-2008, 85% of the mothers had been screened. Screening and prophylaxis were responsible for a decreasing incidence of neonatal infection - from 0.6/1000 to 0.15/1000 live births in Portugal, from 2002 to 2007. However there are some difficulties related to screening. In the second Portuguese study 16/57 NB with early-onset infection (28%) were born to “negative” mothers. Several factors illustrate how difficult is to draw national screening policies: a wide range of carrier’s state rate throughout a country - in Portugal from 12% to 30%. The success of any screening policy may also be affected by additional technical and organizational problems. In countries where home delivery is a tradition or a trend intrapartum GBS prophylaxis requires a very well organized assistance.. Moreover factors usually accepted as protective are not so effective. In the Portuguese study 24/57 infected newborns (42%) were delivery by caesarean section. Another subject deals with the workload in the postnatal ward generated by deficient compliance to the guidelines a problem not confirm by a study of our group. Decreasing the importance of GBS, highlight the importance of E. coli in perinatal infection. From the 16 340 registrations of the National Registry 1676 were newborns with mother-related infection. Applying the same reasoning to E.coli as to GBS and Listeria monocytogenes – that is considering all of them are of maternal origin - 6.7% of these infections were due to E. coli, 4.6% to SGB and 0.5% to Listeria monocytogenes. In conclusion screening and prophylaxis may be not the best way to prevent all GBS neonatal infections but by now it is the only available procedure. The other bacteria continue to demand a high suspicion level and immediate intervention.

RISK FACTORS OF HIV-1 VERTICAL TRANSMISSION (VT) AND THE INFLUENCE OF ANTIRETROVIRAL THERAPY (ART) IN PREGNANCY OUTCOME

In the absence of intervention, the rate of vertical transmission of HIV can range from 15-45%. With the inclusion of antiretroviral drugs during pregnancy and the choice of delivery route this amounts to less than 2%. However ARV use during pregnancy has generated several questions regarding the adverse effects of the gestational and neonatal outcome. This study aims to analyze the risk factors for vertical transmission of HIV-1 seropositive pregnant women living in Rio Grande and the influence of the use of ARVs in pregnancy outcome. Among the 262 pregnant women studied the rate of vertical transmission of HIV was found to be 3.8%. Regarding the VT, there was a lower risk of transmission when antiretroviral drugs were used and prenatal care was conducted at the referral service. However, the use of ART did not influence the outcome of pregnancy. However, initiation of prenatal care after the first trimester had an influence on low birth weight, as well as performance of less than six visits increased the risk of prematurity. Therefore, the risk factors analyzed in this study appear to be related to the realization of inadequate pre-natal and maternal behavior.