101 |
Reaktiv effekt i Dala Energis framtida mellanspänningsnät / Reactive power in the future medium voltage grid of Dala EnergiWelbourn, Mark January 2019 (has links)
Dala Energi has large-scale plans for grid development and wants to have a better understanding of their current reactive power levels along with a future prognosis based on their plans. Changes in line inductance, shunt capacitance, area and placement put Dala Energi on the path to higher charging currents and higher reactive power generation. In addition to causing concerns in their own grid, the increased reactive power generation can present challenges for the owner of the overlying grid. Transmission of reactive power upwards is not permitted in the current contract. Dala Energi’s grid is divided into 3 separate regions with a total of 19 larger substations, 12 of which are points of connection with the overlying grid. At times, 8 of the substations have transmitted reactive power upward and soon it will be all 12. Region 1, where the 20-kV grid is located, is the biggest problem-area today, with upward-transmissions of 1 to 3 MVAr quite common and a considerable increase expected. Region 3 contains more than double the underground cable as the other two areas and might have had much greater side effects from the high shunt capacitance were it not for 3 industrial customers who consume a large portion of reactive power. In the coming years, however, Region 3 is expected to have capacitive reactive power levels nearly equal to those of Region 1. The combined reactive power baseline for all regions is expected to drop by 8.24 MVAr in the coming years. The owner of the overlying grid controls Dala Energi’s 5 largest capacitor banks which have a rated capacity of 11.6 MVAr. With the entire capacity almost always connected, the upward transmission of reactive power becomes much greater. It would be very advisable to meet with the owner, discuss interaction between the two grids and examine the details of the current contract. Compensation for excessive generation of reactive power is needed and is going to be essential in the future. The short-term variation of reactive power levels is so great that the use of fixed rating shunt reactors is ill-advised, especially under the current contract. Compensation with variable shunt reactors is recommended.
|
102 |
Avaliação hidrodinâmica de uma válvula neurológica ajustável por acionamento mecânico / Hydrodynamic evaluation of an adjustable neurological valve by mechanical drivePinto, José Ricardo Camilo 13 December 2013 (has links)
A hidrocefalia é uma doença ocasionada pelo distúrbio na formação, circulação ou absorção do líquido cefalorraquidiano (líquor) que acarreta na elevação da pressão intracraniana. O tratamento mais usual para a disfunção é a derivação ventrículo-peritoneal (DVP) responsável pela drenagem do líquor do ventrículo até o abdômen do paciente, através do implante de um cateter ventricular, uma válvula neurológica e um cateter peritoneal. Desse modo, o presente estudo apresenta o conceito de uma nova válvula neurológica com um mecanismo inovador para alteração da pressão de funcionamento, com um menor custo produtivo e de possível aceitação pelo Sistema Único de Saúde (SUS). A norma ISO 7197 forneceu as diretrizes atendidas no desenvolvimento da válvula neurológica ajustável e as informações para a construção das bancadas de testes, utilizadas para a realização dos ensaios hidrodinâmicos no protótipo do dispositivo valvular. Foram pesquisados os biomateriais empregados na fabricação de válvulas neurológicas comerciais, para a proposição dos materiais necessários para a construção da válvula ajustável por acionamento mecânico proposta. O aparato utilizado nos testes hidrodinâmicos apresentou incertezas experimentais, que não comprometem os resultados e a avaliação do desempenho in vitro do dispositivo testado. O protótipo da válvula resistiu aos testes de vazamento e de refluxo de fluido. As pressões de abertura e de fechamento apresentaram-se adequadas para o início e a interrupção do escoamento na DVP. Também foi obtido o comportamento do diferencial de pressão, em função da vazão, para as quatro classes de funcionamento disponíveis no protótipo testado. A avaliação hidrodinâmica do protótipo da válvula ajustável por acionamento mecânico apresenta resultados satisfatórios no controle da drenagem de líquor, frente a todos os ensaios hidrodinâmicos realizados. / Hydrocephalus is a disease caused by disturbance in formation, circulation or absorption of cerebrospinal fluid (CSF) which causes high intracranial pressure. The most common treatment for the dysfunction is the ventricle-peritoneal shunt responsible for drainage of cerebrospinal fluid from the patient\'s ventricle to the abdomen, through the implant of a ventricular catheter, a neurological valve and a peritoneal catheter. Thus, the present study introduces the concept of a new valve with an innovative mechanism to change the working pressure, with a lower cost of production and possible acceptance by the Brazilian Health System. ISO 7197 provided the guidelines met in the development of adjustable neurological valve and the information for the construction of testing rigs, used for hydrodynamic testing on the valve device prototype. Biomaterials used in manufacturing commercial neurological valves have been researched for proposition of materials needed for the proposed adjustable neurological valve by mechanical drive. The apparatus used in hydrodynamic tests presented experimental uncertainties, which do not compromise the results and evaluation of in vitro performance of the device tested. The prototype of the valve withstood the leak and the fluid backflow testing. The opening and closing pressures were suitable for the beginning and the interruption of the flow in the ventricle-peritoneal shunt. It was also obtained the behavior of the pressure differential, due to the flow, for the four classes of operation available in the prototype tested. Hydrodynamic evaluation of the prototype of the adjustable valve by mechanical drive shows satisfactory results in the control of CSF drain, dealing with all hydrodynamic tests carried out.
|
103 |
Avaliação da acuidade visual em crianças com hidrocefalia : um estudo eletrofisiológico por potencial visual evocado de varredura / Visual acuity evaluation in children with hydrocephalus : an electrophysiological study with sweep visual evoked potentialPereira, Silvana Alves 22 April 2008 (has links)
O objetivo do estudo foi medir a acuidade visual (AV) em crianças com diagnóstico de hidrocefalia, apresentando ou não a válvula de derivação ventricular (DVP). Participaram da pesquisa um total de 55 crianças (34 F e 21M) com diagnóstico de hidrocefalia (45 com DVP e 10 sem DVP), com idade entre zero a 291 semanas (média 74 semanas). A AV foi medida pela técnica do Potencial Visual Evocado de Varredura e os resultados foram comparados a valores de referência (Norcia, 1985b). Os diagnósticos etiológicos que levaram à hidrocefalia foram: hemorragia intracraniana (25 crianças), mielomeningocele (20 crianças) e hidrocefalia congênita (10 crianças). O diagnóstico de hidrocefalia foi estabelecido em média no 16° dia de vida. Verificamos que, 31 crianças tiveram o procedimento realizado com menos de 15 dias do diagnóstico de hidrocefalia enquanto que em 14 a válvula foi instalada após 15 dias. Das 55 crianças avaliadas no 1° exame, 18 fizeram o 2° exame, 13 fizeram o 3° exame, 10 completaram quatro exames e apenas cinco completaram as cinco avaliações. Os resultados mostram que dentre as 101 avaliações de AV realizadas em todas as crianças, 95 exames (94%) se mostraram alterados e seis normais. Não há diferença estatística entre a AV das crianças sem derivação em comparação com aquelas crianças cuja DVP foi realizada com tempo de derivação maior que 15 dias (p = 0.699). Houve, todavia, uma diferença estatística na AV, quando comparamos as crianças, cujas derivações foram realizadas em até 15 dias do diagnóstico da hidrocefalia, com aquelas cuja derivação foi realizada após 15 dias (p = 0.038) ou com aquelas que não foram derivadas (p = 0.031). Crianças que não tiveram complicações na DVP tiveram um melhor resultado de AV quando comparado com o grupo com complicação (p = 0.0001). No grupo de crianças com complicação, novamente aquelas que foram derivadas com tempo inferior a 15 dias do diagnóstico da hidrocefalia apresentou melhores resultados de AV quando comparado com aquelas crianças com complicação cuja derivação foi realizada com mais de 15 dias (p = 0.029). Nós concluímos que é possível a medida da acuidade visual de resolução pelos PVEs de varredura em crianças com diagnóstico de hidrocefalia e os valores geralmente são piores comparando aos valores normativos. O tempo da derivação e o número de complicações decorrentes da DVP parecem interferir nesta diferença. Em nosso conhecimento, este foi o primeiro trabalho a avaliar progressivamente, a acuidade visual de crianças, nos primeiros anos de vida, com hidrocefalia, com ou sem DVP e correlacionar o resultado com o tempo de derivações e número de complicações. Apesar da grande evolução tecnológica alcançada pela oftalmologia, ainda não somos capazes de prevenir as alterações visuais detectáveis pelo simples exame de AV nas crianças com hidrocefalia. O tempo para a inserção da válvula de derivação e o tratamento para as complicações ainda são medidas retardadas devido à prematuridade, instabilidade hemodinâmica e a não autorização do familiar. Estes motivos podem comprometer o desenvolvimento visual destas crianças. / The objective was to measure the visual acuity (VA) of children with the diagnosis of hydrocephalus with or without peritoneal-ventricular shunt (PVS). A total of 55 children with the diagnosis of hydrocephalus (45 with PVS and 10 without PVS) were included in the study (34F and 21M), with an age range of 0 to 291 weeks (mean=74 weeks). The VA was measured by the sweep visual evoked potential technique and the results were compared with reference values proposed by Norcia (1985b). Etiological diagnosis of the hydrocephalus was as follows: intracranial hemorrhage (25 children), meningomyelocele (20 children) and congenital hydrocephalus (10 children). The diagnosis of hydrocephalus was made in an average time of 16 days of life. After the diagnosis, the insertion of the PVS, when made, was accomplished in average on the 16th day. Of those with a PVS, in 31 the ventricular valve was inserted before 15 days after the diagnosis whereas in 14 in shunt was inserted after 15 days. Of the 55 children evaluated in the first exam, 18 were evaluated in a second exam, 13 did the third exam, 10 completed 4 exams and only 5 completed the 5 evaluations. The results of the 101 sweep visual evoked potential performed in all children, 95 exams (94%) were abnormal and only 6 were normal. There was no statistical difference in the VA of children without a ventricular shunt in comparison with those in which the shunt was inserted after 15 days of the diagnosis of hydrocephalus (p=0.699). There was, however, a statistical difference in the VA between children with a ventricular shunt inserted before 15 days of the diagnosis and children with a ventricular shunt after 15 days (p=0.038) or those without a shunt (p=0.031). Children with no complications of the ventricular shunt had a better VA as compared to those with shunt complications (p= 0.0001). In the group of children with complications, again those who had a shunt inserted before 15 days bad better VA results in comparison to those in whom the shunt was inserted after 15days (p=0.029). We concluded that measuring visual acuity by sweep visual evoked potential is feasible in children with the diagnosis of hydrocephalus and that results are usually worse comparing with reference values. The timing for insertion of a ventricular shunt and the occurrence of complications of this procedure are factors that may influence the VA. To our knowledge, this is the first study that progressively evaluated the VA in children, of early age, with hydrocephalus, with or without a ventricular shunt and correlated the VA with the timing and complications of the ventricular shunt. Despite the great technological advance in ophthalmology, we are still unable to prevent visual impairments, detectable by simple visual acuity tests, in children with hydrocephalus. The timing of the insertion of the ventricular shunt and the adequate treatment of the potential complications may be delayed due to prematurity, hemodynamic instability and family refusal. This delay may compromise the visual development of these children.
|
104 |
Fatores associados à hidrocefalia em pacientes com mucopolissacaridoseDalla Corte, Amauri January 2017 (has links)
Introdução: As mucopolissacaridoses (MPS) constituem um grupo de doenças lisossômicas caracterizadas pela deficiência de uma das enzimas responsáveis pela degradação dos glicosaminoglicanos (GAGs). É difícil determinar a incidência precisa de hidrocefalia em pacientes com MPS, pois não possui uma definição formal por consenso. Além disso, é difícil distinguir a hidrocefalia comunicante da dilatação ventricular secundária à atrofia cerebral, porque ambas apresentam características clínicas e neuroradiológicas comuns. Embora várias técnicas sejam usadas para identificar pacientes com MPS com maior probabilidade de ter hidrocefalia e responder ao tratamento cirúrgico, não existe um método definitivo para provar o diagnóstico. Objetivos: Avaliar a relação entre ventriculomegalia, volume cerebral e liquórico, fluxo de líquor aquedutal e cervical e pressão de abertura liquórica em pacientes com MPS, e detectar potenciais biomarcadores para as alterações da circulação liquórica. Métodos: Quarenta e três pacientes com MPS (12 MPS I, 15 MPS II, 5 MPS III, 9 MPS IV A e 2 MPS VI) realizaram testes clínicos e de desenvolvimento neurológico, ressonância magnética (RM) nas sequências T1, T2, FLAIR e por contraste de fase, seguidas por punção lombar para avaliação da pressão de abertura liquórica. Para a análise das variáveis da RM, foram medidos: volume cerebral e liquórico, carga de lesões na substância branca (LSB), índice de Evans, largura do terceiro ventrículo, ângulo do corpo caloso, espaços perivasculares dilatados (EPVD), estenose da junção craniocervical, volume de stroke aquedutal e cervical, e concentração de GAGs no líquor. Resultados: As formas graves e a macrocefalia estiveram significativamente associadas com a ventriculomegalia, principalmente com o índice de Evans (p = 0.004 e p = 0.008, respectivamente). A carga de LSB apresentou uma forte correlação com as medidas ventriculares e o volume liquórico ventricular (rs = 0.51, p = 0.001). A dilatação ventricular supratentorial e o volume de líquor ventricular apresentaram uma correlação moderada com o volume de stroke aquedutal (VSA) (rs = 0.46, p = 0.002). A pressão de abertura liquórica não se correlacionou nem com as três medidas da ventriculomegalia, nem com a volumetria liquórica, nem com o VSA. O prejuízo cognitivo e os EPVD mostraram uma associação significativa com a ventriculomegalia, especialmente com a largura do terceiro ventrículo (p = 0.019 e p = 0.001, respectivamente). Os EPVD em quantidade aumentada também apresentaram uma significativa associação com o VSA elevado (p = 0.007). Conclusões: Nos pacientes com MPS, a ventriculomegalia está associada a um fenótipo grave da doença, maior declínio cognitivo e maior extensão das LSB e EPVD. Existem associações entre as medidas de fluxo liquórico e as medidas relacionadas à volumetria liquórica. Além disso, as medidas volumétricas estão associadas a quantidade de EPVD. / Background: The mucopolysaccharidoses (MPS) are a group of lysosomal diseases characterized by a deficiency in one of the lysosomal enzymes responsible to degrade glycosaminoglycans (GAGs). The precise incidence of hydrocephalus in patients with MPS is hard to determine, because it lacks a formal, consensus-based definition. In addition, it is difficult to distinguish communicating hydrocephalus from ventricular dilatation secondary to brain atrophy, because both share common clinical and neuroradiological features. Although various techniques are used to identify MPS patients who are most likely to have hydrocephalus and respond to surgical treatment, no definitive method exists to prove diagnosis. Objectives: To assess the relationship between ventriculomegaly, brain and cerebrospinal fluid (CSF) volumes, aqueductal and cervical CSF flows, and CSF opening pressure in MPS patients, and to provide potential biomarkers for abnormal CSF circulation. Methods: Forty-three MPS patients (12 MPS I, 15 MPS II, 5 MPS III, 9 MPS IV A and 2 MPS VI) performed clinical and neurodevelopmental tests, and T1, T2, FLAIR and phase-contrast magnetic resonance imaging (MRI) followed by a lumbar puncture with the CSF opening pressure assessment. For the analysis of MRI variables, the following measures were performed: brain and CSF volumes, white matter (WM) lesion load, Evans’ index, third ventricle width, callosal angle, dilated perivascular spaces (PVS), craniocervical junction stenosis, aqueductal and cervical CSF stroke volumes, and CSF GAGs concentration Results: The severe forms and the macrocephaly were significantly associated with the ventriculomegaly, mainly with the Evans’ index (p = 0.004 and p = 0.008, respectively). The WM lesion load presented a high correlation with the ventricular measurements and the ventricular CSF volume (rs = 0.51, p = 0.001). The supratentorial ventricular dilation and the ventricular CSF volume presented a moderate correlation with the aqueductal CSF stroke volume (ACSV) (rs = 0.46, p = 0.002). The CSF opening pressure did not correlate with either the three measures of ventriculomegaly, either with the CSF volumetry or with the ACSV. The cognitive impairment and the dilated PVS showed a significant association with the ventriculomegaly, especially with the width of the third ventricle (p = 0.019 and p = 0.001, respectively). Increased amount of dilated PVS also had a significant association with the elevated ACSV (p = 0.007). Conclusions: In MPS patients ventriculomegaly is associated with a severe phenotype, increased cognitive decline, WM lesion severity and enlarged PVS. There are associations between CSF flow measurements and measurements related to CSF volumetrics. Also, the volumetric measurements are associated with the degree of dilated PVS.
|
105 |
Anatomia venosa no fígado cirrótico com vistas à derivação porto-sistêmica intra-hepática transjugularVasconcelos Filho, José Olímpio Maia de January 2016 (has links)
Introdução – O tratamento da hipertensão portal continua sendo um desafio e muitos desses pacientes necessitam até transplante de fígado, como tratamento definitivo. Nesse contexto a derivação porto-sistêmica intra-hepática transjugular (Transjugular Intrahepatic Portosystemic Shunt – TIPS) surgiu como uma alternativa atraente para esta complicação da doença hepática crônica, sobretudo por não requerer laparotomia e efetivamente reduzir a pressão portal. O conhecimento da distância entre as veias hepáticas e os ramos portais e outros dados anatômicos, no fígado cirrótico, são requisitos importantes no planejamento e execução desse procedimento. Objetivos - Determinar as distâncias e diâmetros das veias hepáticas direita e média para os ramos portais e para a bifurcação da veia porta, no fígado cirrótico humano, com vistas à construção do TIPS. Tipo de estudo – Estudo anatômico descritivo e macroscópico em moldes vasculares de resina obtidos por corrosão de fígados humanos isolados e cirróticos. Material e método – O estudo foi autorizado pelo Comitê de Ética em Pesquisa do HUOC/Procape-UPE e todos os pacientes, ou seus representantes legais, assinaram Termo de Consentimento Livre e Esclarecido. Foram obtidos 21 moldes de resina acrílica dos ramos portais e veias hepáticas de fígados cirróticos, de pacientes transplantados, dos hospitais Jayme da Fonte e Universitário Oswaldo Cruz, do Recife/PE. Após a completa corrosão do parênquima, foram medidas as distâncias e diâmetros das veias hepáticas e ramos da veia porta. Para testar a hipótese de diferença da média estimada em relação a um valor de referência, foi aplicado o teste t-Student para uma amostra. Resultados - A distância média da veia hepática direita para o ramo direito da veia porta e para a sua bifurcação foram, respectivamente, de 33 (±6,4) e 36 (±7,4) mm, ambos significativamente menores (p<0,0001 e p<0,0002) que os resultados encontrados na literatura, em fígados normais. A distância média da veia hepática média para o ramo direito e para o ramo esquerdo da veia porta foi, respectivamente, de 36 (±6,8) e 26 (±8,8) mm . Conclusão – As distâncias entre a veia hepática direita e o ramo direito da veia porta ou a bifurcação da mesma, em fígados cirróticos, foram significativamente menores que as anteriormente relatadas em fígados normais. A veia hepática média é confirmada como uma via alternativa adequada. / Introduction - The treatment of portal hypertension remains a challenge and many of these patients need liver transplantation as definitive treatment. In this context the Transjugular Intrahepatic Portosystemic Shunt (TIPS) has emerged as an attractive alternative to this complication of chronic liver disease, especially for not requiring laparotomy and effectively reducing the portal pressure. Knowing the distance between the hepatic veins and portal branches and other anatomical data in the cirrhotic liver, they are important requirements in the planning and execution of this procedure. Purpose: To determine spatial arrangements and diameters of right and middle hepatic veins relative to portal vein branches in cirrhotic human livers, gaining strategic insight to percutaneous procedures as transjugular intrahepatic portosystemic shunt. (TIPS). Materials and Methods: This study was authorized by an area Research Ethics Committee, and each study subject or legal representative granted signed informed consent. Acrylic corrosion casts of 21 resected cirrhotic livers were generated. Diameters of hepatic veins and portal branches and pertinent intervening distances were measured. To assess differences in estimated average (relative to reference values), Student's t-test for one sample was applied. Results: Mean distances from right hepatic vein to right portal branch and to portal vein bifurcation were 33±6.4 mm and 36±7.4 mm, respectively, both significantly shorter than published reference values in healthy human livers (p<0.0001 and p<0.0002, respectively). Mean distances from middle hepatic vein to right and left branches of portal vein were 36±6.8 mm and 26±8.8 mm, respectively. Conclusion: Distances separating right hepatic vein and portal vein (right branch and bifurcation) are diminished in cirrhotic livers compared to healthy ones. The middle hepatic vein is confirmed as a suitable alternative route.
|
106 |
Implication d'un shunt circulatoire droite-gauche dans les lésions cérébrales latentes chez les plongeursde Maistre, Sébastien 28 September 2004 (has links) (PDF)
Nous avons cherché à décrire le rôle joué par un shunt circulatoire droite-gauche dans la survenue de lésions cérébrales latentes chez les plongeurs. Dix plongeurs, professionnels et sportifs, indemnes d'accident de désaturation avec un minimum de 500 plongées nous ont été adressés par des médecins des sports que nous avions contactés par courrier. Douze jeunes militaires non plongeurs constituaient le groupe témoin. Nous avons recherché la présence d'un shunt droite-gauche par écho Doppler transcrânien. Les lésions cérébrales correspondaient à des hypersignaux de la substance blanche retrouvés à la fois sur les séquences T2 et FLAIR en IRM. On ne réussit pas à mettre en évidence un lien entre la présence d'un tel shunt droite-gauche et la présence d'hypersignaux chez les plongeurs indemnes d'accident de désaturation neurologique aigu. Cependant on a tendance à retrouver une plus grande prévalence de ces hypersignaux en présence d'un shunt de haut grade. En outre alors que la différence n'est pas significative entre le groupe plongeur et le groupe témoin, on trouve significativement plus d'hypersignaux chez les plongeurs les plus expérimentés indépendamment de la présence ou de l'absence de shunt. On propose la réalisation d'une étude sur des plongeurs beaucoup plus expérimentés que ceux des études conduites jusqu'à présent et porteurs de shunts de haut grade.
|
107 |
Negative capacitance shunting of piezoelectric patches for vibration control of continuous systemsBeck, Benjamin Stewart 10 October 2012 (has links)
The ability to reduce flexural vibrations of lightweight structures has been a goal for many researchers. A type of transducer-controller system that accomplishes this is a piezoelectric patch connected to an electrical impedance, or shunt. The piezoelectric patch converts the vibrational strain energy of the structure to which it is bonded into electrical energy. This converted electrical energy is then modified by the shunt to influence to mechanical response. There are many types of shunt circuits which have demonstrated effective control of flexural systems. Of interest in this work is the negative capacitance shunt, which has been shown to produce significant reduction in vibration over a broad frequency range. A negative capacitance circuit produces a current that is 180̊ out of phase from a traditional, passive capacitor. In other words, the voltage of the capacitor decreases as charge is added. The negative capacitance shunt consists of a resistor and an active negative capacitance element. By adding a resistor and negative capacitor to the electrical domain, the shunt acts as a damper and negative spring in the mechanical domain.
The performance of the negative capacitance shunt can be increased through proper selection of the shunt's electrical components. Three aspects of component selection are investigated: shunt efficiency, maximum suppression, and stability. First, through electrical modeling of the shunt-patch system, the components can be chosen to increase the efficiency of the shunt for a given impedance. Second, a method is developed that could be utilized to adaptively tune the magnitude of resistance and negative capacitance for maximum control at a given frequency. Third, with regard to stability, as the control gain of the circuit is increased, by adjusting the circuit parameters, there is a point when the shunt will become unstable. A method to predict the stability of the shunt is developed to aid in suppression prediction.
The negative capacitance shunt is also combined with a periodic piezoelectric patch array to modify the propagating wave behavior of a vibrating structure. A finite element method is utilized to create models to predict both the propagation constant, which characterizes the reduction in propagating waves, and the velocity frequency response of a full system. Analytical predictions are verified with experimental results for both a 1- and 2-D periodic array. Results show significant attenuation can be achieved with a negative capacitance shunt applied to a piezoelectric patch array.
Three electromechanical aspects are developed: design for maximum suppression, more accurate stability prediction, and increased power-output efficiency. First, a method is developed that may be used to adaptively tune the magnitude of resistance and negative capacitance for maximum suppression. Second, with regard to stability, a method is developed to predict the circuit components at which the circuit will obtain a stable output. Third, through electrical modeling of the shunt-patch system, the components are chosen to increase the power output efficiency of the shunt circuit for a given impedance.
The negative capacitance shunt is also combined with a periodic piezoelectric patch array to modify the propagating wave behavior of a vibrating structure. Analytical predictions are verified with experimental results for both a 1- and 2-D periodic array. Results show significant attenuation can be achieved with a negative capacitance shunt applied to a piezoelectric patch array.
|
108 |
Design And Implementation Of Thyristor Switched Shunt CapacitorsUz, Eda 01 February 2010 (has links) (PDF)
This research work deals with the analysis, design and implementation of thyristor switched plain capacitor banks and thyristor switched shunt filter banks. Performances of various thyristor switched capacitor (TSC) topologies are also investigated by simulations. The theoretical findings have been verified by carrying out experimental work on two prototypes implemented within the scope of this research work, one is a wye-connected laboratory prototype and the other is a delta-connected application prototype integrated to some of the SVCs existing in Turkish Coal Enterprise s Plants. The advantages of back-to-back connected thyristor switches over conventional electromechanical contactors are also made clear by conducting an intensive experimental work in the laboratory. A good correlation have been obtained between theoretical and experimental results.
|
109 |
Personer med idiopatisk normaltryckshydrocefalus:deras förväntningar på behandling med shunt och syn på egen roll i rehabiliteringsprocessen-en intervjustudieGustafsson, Agneta January 2015 (has links)
Bakgrund: Det har i vissa fall varit märkbart att patienter med idiopatisk normaltrycks hydrocefalus (iNPH) upplever att förväntat shuntbehandlingsresultat inte uppnåtts och de rapporterar försämring vid den postoperativa uppföljningen trots att standardiserade tester inte visar i den riktningen. Det har också visat sig att rehabiliteringsinsatserna varierat för patienterna allt från strukturerade rehabiliteringsperioder på exempelvis geriatrisk rehabiliteringsenhet till i princip ingen rehabilitering alls. Syfte: Att beskriva vilka förväntningar personer med iNPH har på behandling med shunt och hur de ser på sin egen roll i rehabiliteringsprocessen. Metod: Kvalitativ, deskriptiv design med manifest och induktiv ansats. Datainsamlingen skedde genom semistrukturerade intervjuer med sju patienter med iNPH preoperativt. Resultat: Det fanns en samstämmighet bland informanterna kring förväntningar på shuntbehandlingsresultatet. De rörde den symtomtriad (gång och balansstörning, överaktiv urinblåsa samt kognitiv nedsättning) som ofta finns vid iNPH. Varierade beskrivningar gavs på hur symtomen påverkade informanterna. Det fanns också en uppfattning bland informanterna att de hade ett eget ansvar i rehabiliteringsprocessen och förslag framkom på vad de själva kunde bidra med i processen men också olika hinder för att utöva fysisk aktivitet beskrevs. Slutsats: Förväntningar på shuntbehandlingsresultat behöver diskuteras med patienten (ibland även anhörig) inför shuntbehandling redan vid beslut om operation men också då patienten läggs in för behandlingen. Rehabiliteringsprocessen behöver också diskuteras med patienten såväl före shuntoperation som tidigt postoperativt. Detta är troligtvis mycket viktigt för att uppnå ett så optimalt behandlingsresultat som möjligt. / Background: It has been noticeable that some patients with idiopathic normal pressure hydrocephalus (iNPH) find the expected result of shunt treatment not achieved and they report detoriation at postoperative follow-up even though standardized tests do not show results in that direction. It has also been shown that rehabilitation possibilities for patients varied, ranging from structured rehabilitation periods, e.g. at geriatric rehabilitation units to basically no rehabilitation at all. Objective: To describe what expectations patients with iNPH have on treatment with shunt and how they view their own role in the rehabilitation process. Method: A quality, descriptive design with manifest and inductive approach. The data collection was done by semi-structured interviews with seven patients with iNPH preoperative. Results: There was consensus among informants regarding the expectations on the result of shunt treatment. The expectations concerned the symptom triad (gait-and balance disturbance, urgency bladder and cognitive dysfunction) which often occurs in iNPH. Varied descriptions were given on how the symptoms had affected the informants. There was also an opinion among the informants that they had own responsibility for the rehabilitation process and suggestions were given on what they could contribute with in the process but also different obstacles for performing physical activities were described. Conclusion: Expectations on shunt treatment results need to be discussed with the patient (sometimes together with a relative) prior to shunt treatment, already when the patient is offered a shunt operation and also on the day before operation when the patient is in the neurosurgery clinic. The rehabilitation process also needs to be discussed with the patient before the shuntoperation as well as early postoperative. This is probably very important in order to achieve as optimal treatment results as possible.
|
110 |
Die Serumkonzenztrationen von S-100B bei Leberzirrhose und transjugulärem intrahepatischen portosytemischen Stent-Shunt in Abhängigkeit von der minimalen hepatischen Enzephalopathie der Leber- und der Nierenfunktion / Serum concentrations of S100B in liver cirrhosis and transjugular intrahepatic portal-systemic stent-shunt in relation to minimal hepatic encephalopathy, liver and kidney functionSchumann-Binarsch, Silke 16 February 2015 (has links)
No description available.
|
Page generated in 0.0346 seconds