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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
641

Profiling children with neural tube defects and exploring experiences of mothers

Simpamba, Micah Mutuna January 2012 (has links)
Magister Scientiae (Physiotherapy) - MSc(Physio) / Neural tube defects (NTDs) are the world‘s second most common birth defects after cardiovascular defects. In developing countries, poor access to health care services among children with NTDs contributes to early infant deaths, while those who survive live with severe disabilities. In Zambia, all children with NTDs in need of surgery are referred to Lusaka and physiotherapy services are not available in health facilities below the first level hospitals. The aim of the current study was to determine the profile of children with NTDs and to explore the experiences of mothers with accessing health care services for these children. The study which was conducted at the University Teaching Hospital (UTH) in Lusaka consisted of both quantitative and qualitative methods. The quantitative phase consisted of a retrospective record review of children with NTDs, who were admitted to UTH from January to December, 2010. A sample of 50 medical records was used based on available records, and data collection was done using a data extraction sheet which was specifically designed for the study. Analysis of quantitative data was done using Statistical Package for Social Science (SPSS) version 20.0. The qualitative phase had two parts, with the first part involving in-depth interviews with a purposefully selected sample of 20 mothers of children who were admitted to UTH. The second part used a sample of convenience of four mothers who had brought their children for follow up visits. All interviews were audiotaped, transcribed verbatim and translated, and recurring ideas were coded and collapsed into categories and themes. Permission to conduct the study was obtained from the UWC Research Grant and Study Leave Committee, University of Zambia Research Ethics Committee, and University Teaching Hospital management. Informed written consent was obtained from the mothers who accepted to take part in the study. Results from the record review revealed that the majority of children were from Lusaka province, with ages ranging from one day to 48 months and a male predominance of 58%. Myelomeningocele was the most common type of NTD (44%) with the lumbar region being the common site (52%). Hydrocephalus was present in 74% of children, 30% of children had both paraplegia and incontinence and 22% (n=11) of the files had no information on the neurological impairments. Wound infection was present in 40% (n=20) of the children. The majority (66%) of children were lost to follow up. Mothers of children who were admitted in UTH cited transport to UTH and back home as the main challenge. Other challenges included the lack of a prenatal diagnosis, the need for information, uncertainty about future of their children, and concerns about their family. Interviews with mothers on experiences with accessing physiotherapy services found that the lack of knowledge among mothers was the main reason children were not accessing physiotherapy services. Findings on access to health care were related to the ―Four A‘s‖ access theory which consists of four dimensions of access namely geographical accessibility, availability, affordability and acceptability. It is recommended that health care providers and policy makers ensure that all children with NTDs are provided with free transport to and from referral hospitals. Policy makers need to consider involving physiotherapists in out-reach programmes and mobile clinics to ensure access to physiotherapy services for all children in need of the service. Health care providers must also ensure that they give adequate information to mothers of children born with birth defects as this enhances their access to appropriate health care services.
642

Bibehållen position av endotrakealtub i munhålan : en kvantitativ deskriptiv tvärsnittsstudie / Maintaining the position of the endotracheal tube in the mouth : a quantitative descriptive cross-sectional study

Assadzadeh, Kamran January 2013 (has links)
Bakgrund: På intensivvårdsavdelningar finns olika rutiner kring huruvida endotrakealtubens position hos intuberade skall skiftas eller bibehållas i samma mungipa, då sidbyten kan leda till allvarliga komplikationer. Rutinen vid CIVA har varit att byta endotrakealtubens position på alla intuberade patienter en gång per dygn. Varken rutinen med skifte samt bibehållen position har utvärderats. Syftet med studien är att undersöka oralt intuberade patienters munhälsa vid bibehållen position av endotrakealtub under vårdtiden. Metod: Studien är en kvantitativ deskriptiv tvärsnittsstudie. Ett protokoll utformades för att undersöka hur stor andel av patienterna som får tryckskador i munnen med bibehållen tublägesposition. Resultat: Av totalt 85 oralt intuberade patienter utvecklade 10 rodnad och 7 sår medan 68 hade helt intakt slemhinna. Flest nyupptäckta sår uppkom efter 3-4 dagars intubering medan rodnader var jämnt fördelat. Slutsats: Endast ett fåtal patienter utvecklade tryckskador. Rutinen att bibehålla endotrakealtuben i samma position lämpar sig på patientkategorin på CIVA eftersom medelvårdtiden för intuberade är 3,2 dagar och flertalet extuberas under de 3 första dagarna. Klinisk betydelse: Studien ligger till grund för CIVA:s ändrade rutin att bibehålla endotrakealtubspositionen i samma mungipa och skulle på sikt kunna bidra till att minska samhällskostnaderna genom att reducera förekomsten av VAP och därmed patientvårdtiden / Background: Intensive care units have different routines whether the endotracheal tube position should be shifted or maintained in the same corner of the mouth. Repositioning of the tube can lead to serious complications. The routine at CIVA has been to change the endotracheal tube position in all intubated patients once per day. None of the routines have been evaluated. The objective of this study is to examine the oral health of intubated patients with maintained tube position. Method: The study is a quantitative descriptive cross-sectional study. A protocol was designed to examine the proportion of patients receiving pressure sores in the mouth. Results: Of a total of 85 orally intubated patients, 10 developed redness and 7 wounds while 68 had intact mucosa. The majority of the newly discovered sores occurred after 3-4 days of intubation. Conclusion: Only a few patients developed pressure sores. The routine to maintain the endotracheal tube in the same position is suitable for the patient category at CIVA since the average length of stay for intubated is 3.2 days and the majority were extubated during the first 3 days . Clinical significance: This study is the basis for CIVA's changed routine to maintain the endotracheal tube position in the same corner of the mouth and could eventually help to reduce the costs for society by reducing the incidence of VAP and thus patient care period.
643

Studies On Shock Wave Attenuation In Liquids

Bhaskar, K 02 1900 (has links) (PDF)
The attenuation mechanism of shock waves of arbitrary strength propagating in air has been reasonably well understood. On the other hand, very little is known about the precise mechanism of shock wave attenuation and energy dissipation in liquids. The equation of state for shock propagation in water is empirical in nature and considerable differences exist with reference to the exact value of various constants even in the cast of Tait’ s equation of state, which is popularly used by researchers to describe the shock wave propagating through water. In recent times, considerable attention is being focused by researchers on shock wave attenuation and associated features in liquid medium mainly in the backdrop of development of many innovative industrial applications of shock waves. The present study focuses on generating reliable experimental data on shock wave attenuation in liquids of different viscosity. Experiments have been performed in a conventional vertical shock tube and a modified diaphragmless shock tube to understand how shock wave of requisite strength attenuates in liquids. A new vertical shock tube was designed, fabricated and successfully tested in the laboratory as a part of this study. In this new facility shock loading experiments with liquids or any complex fluid medium can be carried out. In the present study five liquids (Water, Castor Oil, Sodium Chloride (10%NaCl aqueous solution), Kerosene and Glycerin) have been subjected to shock wave loading. Exhaustive static pressure measurements in the liquid medium have been carried out to understand the attenuation characteristics of shock waves. The validity of Taits equation state has been experimentally verified for water. Based on the experimental results modified Taits equation of state has been obtained for castor oil, sodium chloride, kerosene and glycerin. Illustrative theoretical study is also carried out to complement the experiments.
644

Application of Multiobjective Optimization in Chemical Engineering Design and Operation

Fettaka, Salim January 2012 (has links)
The purpose of this research project is the design and optimization of complex chemical engineering problems, by employing evolutionary algorithms (EAs). EAs are optimization techniques which mimic the principles of genetics and natural selection. Given their population-based approach, EAs are well suited for solving multiobjective optimization problems (MOOPs) to determine Pareto-optimal solutions. The Pareto front refers to the set of non-dominated solutions which highlight trade-offs among the different objectives. A broad range of applications have been studied, all of which are drawn from the chemical engineering field. The design of an industrial packed bed styrene reactor is initially studied with the goal of maximizing the productivity, yield and selectivity of styrene. The dual population evolutionary algorithm (DPEA) was used to circumscribe the Pareto domain of two and three objective optimization case studies for three different configurations of the reactor: adiabatic, steam-injected and isothermal. The Pareto domains were then ranked using the net flow method (NFM), a ranking algorithm that incorporates the knowledge and preferences of an expert into the optimization routine. Next, a multiobjective optimization of the heat transfer area and pumping power of a shell-and-tube heat exchanger is considered to provide the designer with multiple Pareto-optimal solutions which capture the trade-off between the two objectives. The optimization was performed using the fast and elitist non-dominated sorting genetic algorithm (NSGA-II) on two case studies from the open literature. The algorithm was also used to determine the impact of using discrete standard values of the tube length, diameter and thickness rather than using continuous values to obtain the optimal heat transfer area and pumping power. In addition, a new hybrid algorithm called the FP-NSGA-II, is developed in this thesis by combining a front prediction algorithm with the fast and elitist non-dominated sorting genetic algorithm-II (NSGA-II). Due to the significant computational time of evaluating objective functions in real life engineering problems, the aim of this hybrid approach is to better approximate the Pareto front of difficult constrained and unconstrained problems while keeping the computational cost similar to NSGA-II. The new algorithm is tested on benchmark problems from the literature and on a heat exchanger network problem.
645

Blast Performance of Reiforced Concrete Beams Constructed with High-Strength Concrete and High-Strength Reinforcement

Li, Yang January 2016 (has links)
This thesis focuses on the dynamic and static behaviour of reinforced concrete beams built using high-strength concrete and high-strength steel reinforcement. As part of this study, a total of 8 high-strength concrete beams, built with and without steel fibres, and reinforced with high strength ASTM A1035 bars are tested under simulated blast loading using the University of Ottawa shock-tube, with an additional 3 companion beams tested under quasi-static loading. The variables considered in this study include: concrete type, fibre content, steel reinforcement ratio and steel reinforcement type. The behaviour of the beams with high-strength steel bars is compared to a companion set of beams reinforced with conventional steel reinforcement. The criteria used to evaluate the blast performance of the beams includes: overall blast capacity, maximum and residual displacements, secondary fragmentation and crack control. The dynamic results show that high strength concrete beams reinforced with high-strength steel are able to resist higher blast loads and reduce displacements when compared to companion beams with conventional steel reinforcement. The results also demonstrate that the addition of steel fibres is effective in controlling crack formation, minimizing secondary blast fragments, reducing displacements and further increasing overall blast capacity. However, the use of high-strength steel and high-strength concrete also shows potential for brittle failures under extreme blast pressures. The static results show that specimens with high-strength steel bars do not increase beam stiffness, but significantly increase peak load carrying capacity when compared to beams with the same ratio of conventional steel reinforcement. The analytical research program aims at predicting the response of the test beams using dynamic inelastic single-degree-of-freedom (SDOF) analysis and includes a sensitivity analysis examining the effect of various modelling parameters on the response predictions. Overall the analytical results demonstrate that SDOF analysis can be used to predict the blast response of beams built with high-strength concrete and steel reinforcement with acceptable accuracy.
646

Propagation d’un choc dans un milieu hétérogène / Shock propagation in a heterogeneous medium

Elbaz, Déborah 03 November 2011 (has links)
Dans le cadre de la fusion par confinement inertiel en attaque directe, l'utilisation de mousses en tant qu'ablateur permet de réduire les instabilités hydrodynamiques créées sur la cible par l'irradiation directe des faisceaux laser. Des études antérieures ont été réalisées en considérant cette mousse comme homogène. Or, étant composée de fibres de CH baignant dans du DT, elle présente un aspect hétérogène. Le but de cette thèse est d'étudier l'effet de cette hétérogénéité sur la vitesse du choc lors de l'irradiation laser de la cible. Une étude expérimentale sur tube à choc et des études numériques avec le code HERA nous ont permis de trouver que le choc se propage plus rapidement dans le milieu hétérogène que dans le milieu homogène de densité moyenne équivalente. Cette écart de vitesse dépend du taux de présence des fibres de CH, du rapport de densité entre les deux matériaux constituant la mousse, de leur coefficient adiabatique et de la géométrie de la mousse. Nous avons modélisé la mousse de diverses manières, en partant du plus simple au plus compliqué, afin de se rapprocher d'une configuration réaliste. La modification de la vitesse du choc étant dûe à la baroclinicité qui, lors de l'interaction du choc avec l'interface entre le CH et le DT, crée un dépôt de vorticité, responsable de l'accélération du choc. Par conséquent, une interface plane et perpendiculaire au front de choc maximise ce dépôt de vorticité et augmente les écarts de vitesse entre milieux hétérogènes et homogènes. Une corrélation entre l'énergie cinétique derrière le choc et la différence relative des vitesses de choc a été trouvée. Nous avons comparé nos résultats à deux modèles analytiques, mais le système n'étant pas fermé, nous ne pouvons pas, pour le moment, élaborer de modèle prédictif. / In the frame of the inertial confinement fusion in direct drive, the use of CH(DT) foams as ablator allows the reduction of hydrodynamic instabilities created on the target by the direct laser irradiation. In the past, studies have been carried out considering this foam to be a homogeneous medium. Yet, the foam is composed of CH and DT, so it presents heterogeneous features. We study the effects of the heterogeneity on the shock velocity when the laser irradiates the target. Thanks to experimental and numerical studies, we show that the shock propagates faster in the heterogeneous medium than in the homogeneous one with the same averaged density. This velocity gap depends on the presence rate of the CH fibers in the foam, the density ratio, the adiabatic coefficient and the foam geometry. We modelize the foam by different ways, more and more complex. The shock velocity modification is due to the baroclinicity which, during the interaction between the shock front and the interface, creates a vorticity deposition, responsible for the shock accceleration. Accordingly, a interface, which is plane and perpendicular to the front shock, maximises the vorticity deposition and increases the velocity gaps between heterogeneous and homogeneous media. We found a correlation between the kinetic energy behind the shock front and the velocities relative difference. We compared our results with two analytical models. However, the system is not closed, so we can't, for the moment, develop a predictiv model.
647

Influência dos parâmetros envolvidos no processo de união por interferência de tubos por cravamento eletromagnético

Geier, Martin January 2014 (has links)
A união por conformação eletromagnética de perfis tubulares de alta condutividade elétrica é um processo inovador e limpo que pode substituir com sucesso os processos convencionais de união baseados na fixação mecânica por parafusos, rebites, soldagem e adesivos estruturais. Esta tecnologia funciona a temperatura ambiente, permite a união de materiais diferentes e oferece potencial para promover novas aplicações na montagem de estruturas leves. Neste trabalho busca-se compreender a união por interferência de tubos por cravamento eletromagnético em termos de seus principais parâmetros com o objetivo de identificar a influência na resistência global das uniões e estabelecer a faixa útil de condições operacionais do processo. Inicialmente são apresentados os fundamentos teóricos do processo de conformação eletromagnética e suas principais variantes operacionais, seguido de um resumo do estado atual do conhecimento da aplicação desta tecnologia na união de perfis tubulares no qual é verificado que os parâmetros mecânicos são a tensão residual no mandril, a área e forma da zona de união e o coeficiente de atrito entre os componentes. Entretanto, tais parâmetros estão relacionados de forma complexa com o processo de cravamento eletromagnético, a começar pela energia e a distribuição do pulso de pressão magnética gerados pela máquina e ferramenta que “disparam” o processo de conformação, a folga inicial entre componentes, o material dos componentes e, a geometria, forma e rugosidade do mandril. O estudo experimental foca a união por interferência de tubos de alumínio (AA6082-O) com mandris de aço (AISI 1045) e alumínio (AA6082 nos estados O e T6) investigando de forma gradual a influência de parâmetros do processo na resistência mecânica (à tração) deste tipo de uniões. Os resultados obtidos demonstram que a resistência mecânica da união e os modos de falha associados são diretamente relacionados com os parâmetros de processo e condições do mandril. Além disso, outras importantes contribuições são apresentadas em relação à instrumentação para medição de fluxo magnético e eficiência global do processo e para o desenvolvimento e aplicações industriais desta tecnologia. / Joining of tubular profiles with high electrical conductivity by electromagnetic forming (EMF) is an innovative and clean technology that can successfully replace conventional joining technologies based on mechanical fixing with fasteners, rivets, welding and structural adhesives. The technology works at room temperature, allows joining dissimilar materials and offers potential to foster new applications in the assembly of lightweight tubular frame structures. This work investigates the interference-fit joining of tubes by electromagnetic crimping in terms of its major parameters with the aim of identifying their influence on the overall strength of the joints and establishing the useful range of process operating conditions. Initially, the theoretical principles of EMF and its main operational process variants are presented, followed by a summary of the current state of the knowledge of its application in the joining of tubular profiles in which it is found that the mechanical parameters are the residual stress at the joint interface, the area and shape of the joint interface and the friction coefficient between the joining partners. However, these parameters are related in a very complex way with the electromagnetic crimping process parameters, starting with the charging energy and by the machine and tool which generates the distribution of the magnetic pressure pulse that “triggers” the forming process, the initial gap between joining partners, the mandrel properties such as material, geometry, shape and surface roughness. The experimental study focuses the interference-fit of aluminum tubes (AA6082-O) on mandrels made of different materials and metallurgical conditions (AISI 1045, AA6082-O and AA6082-T6) and, therefore, the process is analyzed by the gradual influence of other process parameters aiming to achieve high strength joints. Results show that the joint strength and the associated failure mechanisms are directly related to process parameters and mandrel conditions. In addition, other important contributions are presented regarding the instrumentation for measuring the magnetic flux and overall process efficiency and to the development and implementation of this technology in industrial processes.
648

Separador solido-liquido para operação em fundo de poços de petroleo / Swirl tubes as a downhole desander device

Martins, Jason Alves 09 April 2006 (has links)
Orientador: Eugenio Spano Rosa / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-07T21:12:52Z (GMT). No. of bitstreams: 1 Martins_JasonAlves_M.pdf: 1693632 bytes, checksum: 9c8933692155bfbbb91d774a1f849391 (MD5) Previous issue date: 2006 / Resumo: O presente trabalho investiga os mecanismos de separação sólido-líquido em separadores tubo-ciclônicos. O trabalho é desenvolvido a partir de testes experimentais e simulação numérica. A etapa experimental investiga a influência do aumento de viscosidade sobre a eficiência do separador. Através de uma análise dimensional, os dados experimentais são reduzidos em grupos adimensionais. Obtem-se uma correlação entre a eficiência de separação e os grupos adimensionais. Ela revela como a eficiência depende dos parâmetros geométricos e operacionais do separador. A correlação obtida possibilita dimensionar estes separadores para cenários com elevada viscosidade. As simulações numéricas são realizadas utilizando um método de volumes finitos. O processo de separação é estudado através do adimensional Stokes. São introduzidos os conceitos de superfície de captura e tempo de residência de partículas. Define -se um importante parâmetro do escoamento, o comprimento de decaimento. Propõe-se um modelo unidimensional para o separador. Realiza-se com base neste modelo uma análise comparativa entre dois separadores. Os resultados são coerentes com dados experimentais e indicam quais características geométricas melhoram a eficiência do separador / Abstract: This work investigates the solid-liquid separation mechanisms in swirl tubes through experimental and numerical analysis. In the experimental phase, it is analyzed the impact of the viscosity increase on the separation efficiency of swirl tubes. The experimental data are reduced using dimensional analysis. A functional relationship between the separation efficiency and the dimensionless groups is obtained, allowing to calculate the separation efficiency dependency on the liquid viscosity, flow rate, particle size, and other geometrical parameters of the separator. This relationship helps to design these desander devices to scenarios with high viscosity. Numerical simulations are carried out in a structured grid using a finite volume method. Separation process is studied through the Stokes number. The concepts of capture surface and residence time of particles are introduced and an important flow field parameter, the length of decay is defined. A one-dimensional model is proposed for the swirl tube. A comparative analysis between two separators is done based on the one-dimensional model. The results are in agreement with experimental data and indicate which geometrical features help to improve the separator efficiency / Mestrado / Termica e Fluidos / Mestre em Engenharia Mecânica
649

Caracterização da população de recém-nascidos com diagnóstico de encefalocele / Characterization of the population of newborns diagnosed with encephalocele

Zomignani, Andrea Peterson, 1979- 22 August 2018 (has links)
Orientadores: Sergio Tadeu Matins Marba, Helder José Lessa Zambelli / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-22T03:05:39Z (GMT). No. of bitstreams: 1 Zomignani_AndreaPeterson_M.pdf: 1128762 bytes, checksum: 59ae9805910c4b220c7bfa8d2e7bcbab (MD5) Previous issue date: 2012 / Resumo: Objetivo: Descrever uma população de recém-nascidos com encefalocele. Método: Estudo restrospectivo, descritivo e analítico por análise dos prontuários de recém-nascidos com diagnóstico de encefalocele, no Hospital da Mulher Prof. Dr. José Aristodemo Pinotti - Centro de Atenção Integral à Saúde da Mulher (CAISM), da Universidade Estadual de Campinas (UNICAMP). Foram incluídos todos os pacientes nascidos com diagnóstico de encefalocele no período de janeiro/1997 a julho/2008. Foram estudados: idade materna, paridade, pré-natal, apresentação fetal, tipo de parto, sexo, idade gestacional, índice de Apgar, peso, tipo de encefalocele, tratamento cirúrgico, ocorrência de óbitos, período de internação e retardo do desenvolvimento neuropsicomotor (RDNPM). Foram calculadas as frequências para cada variável analisada e a associação entre algumas variáveis foi verificada estatisticamente pelos testes qui-quadrado e exato de Fisher, considerando alfa de 5%. Resultados: Foram analisados 43 casos com prevalência de 1,24/1000 nascimentos. A faixa de idade materna de maior ocorrência foi 18 a 32 anos (83%), em mães não primigestas (65%), que fizeram os exames pré-natais (95%). A apresentação fetal mais recorrente foi cefálica (45%) com parto cesáreo (65%). Foram encontrados mais casos em meninas, com idade gestacional _37 semanas, tendo a maioria das crianças com a malformação nascido a termo (79%). No primeiro minuto houve Apgar menor ou igual a 7 em 58% dos casos. Em 67% dos casos o peso foi adequado, 27% foram baixo peso e 4,6% muito baixo peso. O tipo de encefalocele mais prevalente foi occipital e em 67% dos casos houve cirurgia. O óbito ocorreu em 31% dos recém nascidos e 55% tiveram período de internação de 1 a 15 dias. Em 62% dos casos foi descrito retardo do desenvolvimento neuropsicomotor. Conclusões: A prevalência de encefalocele foi de 1,24/1000 nascimentos e esteve associada às mães jovens e não primigestas. A apresentação cefálica foi à apresentação mais comum e o tipo de parto mais frequente foi parto cesáreo. Foi mais comum a presença de encefalocele em meninas, com idade gestacional _37 semanas, em nascidos a termo, com índice de Apgar baixo e com peso adequado. A maioria teve encefalocele occipital e precisou de cirurgia, sendo a taxa de mortalidade alta. Na maioria dos casos houve RDNPM / Abstract: Objective: To describe a serie of newborns with encephalocele. Method: Retrospective, descriptive and analytical study, with medical records analysis of newborns with encephalocele, born at the Hospital da Mulher Prof. Dr. José Aristodemo Pinotti - Center for Integral Assistance to Women's Health at the University of Campinas (UNICAMP). All the patients born with these conditions were selected from January/1997 until July/2008. It was studied: maternal age, parity, prenatal care, fetal presentation, mode of delivery, gender, gestational age, Apgar score, birth weight, type of encephalocele, surgical treatment, occurrence of death, hospitalization period, delayed neuropsychomotor development. Frequencies were calculated for each variable and the association among then were assessed statistically using the chi-square and Fisher exact test, considering a 5% alpha. Results: There were 43 cases with prevalence of 1,24/100 births. Maternal age range most frequent was 18 to 32 years (83%), in not primigravidae (65%), who made the prenatal care (95%). The most recurrent fetal presentation was cephalic (45%) with cesarean sections (65%). More cases were found in girls, with gestational age _37 weeks, with the majority of infants with malformations born at term (79%). First minute Apgar score was less than or equal to 7 in 58% of the cases. In 67% of the cases the weight was appropriate, 27% were low birth weight, and 4,6% were very low birth weight infants. The most prevalent type of encephalocele was occipital; 67% of the cases were underwent the surgery. Death occurred in 31% of the newborns and hospitalization period, in most cases, was 1 to 15 days. Neuropsychomotor development delay was observed in 62% of the cases. Conclusions: The prevalence of encephalocele was 1,24/1000 births and there was associated with young mothers and not primiparous. The cephalic presentation was common and there were more cesarean sections. It was more common the presence of encephalocele in girls, with gestational age _37 weeks in term newborns with low Apgar score and appropriate weight. Most had occipital encephalocele and needed surgery, and there was a high mortality rate. In most cases there were neurological deficit / Mestrado / Saude da Criança e do Adolescente / Mestra em Ciências
650

Seismic Performance of Hybrid Fiber Reinforced Polymer-Concrete Pier Columns

Shi, Yilei 14 July 2009 (has links)
As part of a multi-university research program funded by NSF, a comprehensive experimental and analytical study of seismic behavior of hybrid fiber reinforced polymer (FRP)-concrete column is presented in this dissertation. Experimental investigation includes cyclic tests of six large-scale concrete-filled FRP tube (CFFT) and RC columns followed by monotonic flexural tests, a nondestructive evaluation of damage using ultrasonic pulse velocity in between the two test sets and tension tests of sixty-five FRP coupons. Two analytical models using ANSYS and OpenSees were developed and favorably verified against both cyclic and monotonic flexural tests. The results of the two methods were compared. A parametric study was also carried out to investigate the effect of three main parameters on primary seismic response measures. The responses of typical CFFT columns to three representative earthquake records were also investigated. The study shows that only specimens with carbon FRP cracked, whereas specimens with glass or hybrid FRP did not show any visible cracks throughout cyclic tests. Further monotonic flexural tests showed that carbon specimens both experienced flexural cracks in tension and crumpling in compression. Glass or hybrid specimens, on the other hand, all showed local buckling of FRP tubes. Compared with conventional RC columns, CFFT column possesses higher flexural strength and energy dissipation with an extended plastic hinge region. Among all CFFT columns, the hybrid lay-up demonstrated the highest flexural strength and initial stiffness, mainly because of its high reinforcement index and FRP/concrete stiffness ratio, respectively. Moreover, at the same drift ratio, the hybrid lay-up was also considered as the best in term of energy dissipation. Specimens with glassfiber tubes, on the other hand, exhibited the highest ductility due to better flexibility of glass FRP composites. Furthermore, ductility of CFFTs showed a strong correlation with the rupture strain of FRP. Parametric study further showed that different FRP architecture and rebar types may lead to different failure modes for CFFT columns. Transient analysis of strong ground motions showed that the column with off-axis nonlinear filament-wound glass FRP tube exhibited a superior seismic performance to all other CFFTs. Moreover, higher FRP reinforcement ratios may lead to a brittle system failure, while a well-engineered FRP reinforcement configuration may significantly enhance the seismic performance of CFFT columns.

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