Implementação experimental de filtro ativo paralelo de potência com aplicação a gerador de indução trifásico

This work describes the experimental implementation of a shunt active power filter applied to a three-phase induction generator. The control strategy of active filter turned to the excitation control of the machine and to decrease the harmonics in the generator output current. Involved the implementation of a digital PWM switching, and was made a comparison of two techniques for obtaining the reference currents. The first technique is based on the synchronous dq reference method and the second on the theory of instantaneous power. The comparison is performed via simulation and experimental results. To obtain the experimental results, was mounted a bench trial and the control and communications needed were implemented using DSP - MS320F2812. The simulation results and experimental data proved the efficiency of the filter to apply, highlighting the technique of instantaneous power

Estratégia de controle robusto para filtro ativo paralelo sem detecção de harmônicos de correntes

Conventional control strategies used in shunt active power filters (SAPF) employs real-time instantaneous harmonic detection schemes which is usually implements with digital filters. This increase the number of current sensors on the filter structure which results in high costs. Furthermore, these detection schemes introduce time delays which can deteriorate the harmonic compensation performance. Differently from the conventional control schemes, this paper proposes a non-standard control strategy which indirectly regulates the phase currents of the power mains. The reference currents of system are generated by the dc-link voltage controller and is based on the active power balance of SAPF system. The reference currents are aligned to the phase angle of the power mains voltage vector which is obtained by using a dq phase locked loop (PLL) system. The current control strategy is implemented by an adaptive pole placement control strategy integrated to a variable structure control scheme (VS¡APPC). In the VS¡APPC, the internal model principle (IMP) of reference currents is used for achieving the zero steady state tracking error of the power system currents. This forces the phase current of the system mains to be sinusoidal with low harmonics content. Moreover, the current controllers are implemented on the stationary reference frame to avoid transformations to the mains voltage vector reference coordinates. This proposed current control strategy enhance the performance of SAPF with fast transient response and robustness to parametric uncertainties. Experimental results are showing for determining the effectiveness of SAPF proposed control system

Fault Current Limiter Using YBCO Coated Conductor-The Limiting Factor and Its Recovery Time

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Implante de filtro em veia cava inferior dupla: relato de caso e revisão da literatura

Veia cava inferior dupla é uma variação anatômica rara cuja prevalência é de 0,2-3%. O implante de filtro de veia cava, quando indicado em casos com duplicidade da veia cava inferior, pode ser realizado de diferentes formas: em ambas as veias cavas; em uma delas, embolizando a anastomose entre ambas; em somente uma delas; ou por implante supra-renal. Relatamos um caso de trombose venosa profunda no pós-operatório de implante de prótese de quadril com contra-indicação para tratamento anticoagulante e cuja cavografia evidenciou duplicidade de veia cava inferior. O implante de filtro de veia cava inferior realizado em posição supra-renal mostrou-se opção adequada e segura.

Trombectomia na angioplastia primária em ponte de safena

O emprego da trombectomia na angioplastia primária demonstra bons resultados clínicos e angiográficos imediatos, por meio de redução da embolização distal e do fenômeno do no-reflow e otimização da perfusão miocárdica. Essa técnica, principalmente usada em artérias coronárias, em raras oportunidades é descrita quando empregada em pontes de safena aortocoronarianas. Relatamos o caso de um paciente de 67 anos com infarto agudo do miocárdio relacionado a oclusão de ponte de safena e submetido a trombectomia com bons resultados.

Neurocisticercose e síndrome de lennox-gastaut: relato de caso

Relata-se o caso de uma menina que, aos 2 anos de idade, apresentou a forma epiléptica, hidrocefálica e encefalítica da neurocisticercose, diagnosticada por exame do líquido cefalorraqueano e tomografia computadorizada de crânio, evolução com crises polimórficas, episódios de descompensação da hipertensão intracraniana por obstrução do sistema de derivação ventriculoperitoneal, retardo no desenvolvimento neuropsicomotor e cegueira até que, aos 10 anos de idade, foi diagnosticada síndrome de Lennox-Gastaut. Atualmente, a paciente tem 16 anos, apresenta sequelas neurológicas e crises parciais complexas com automatismos, parcialmente controladas com o uso de clobazan e oxcarbazepina. A primeira associação de neurocisticercose e síndrome de Lennox-Gastaut foi descrita em 1973, por Frochtengarten & Scarante, em uma menina com quadro clínico semelhante ao do caso relatado.

Aspectos clínicos e evolutivos da hidrocefalia na neurocisticercose

Com o propósito de analisar os aspectos clínicos da hidrocefalia (HDC) na neurocisticercose (NCC), realizou-se o estudo retrospectivo de 47 prontuários de pacientes com HDC e NCC. Verificou-se que 70,2% eram homens, entre 21 e 50 anos. A hipertensão intracraniana (HIC) ocorreu em todos os pacientes, cefaléia (CEF) em 89,4%, meningoencefalite (ME) em 80,8% e distúrbios psíquicos (PSI) em 74,5%. A síndrome liquórica da NCC foi detectada em 65,9% pacientes. Além da HDC, as tomografias computadorizadas de crânio (TC) mostraram lesões císticas e edema cerebral difuso em 59,6% cada, calcificações em 55,3%. Dos 41 pacientes (87,2%) com derivação ventriculoperitoneal (DVP), em 22 (53,7%) deles foram necessárias uma a sete revisões/paciente (média=3). A evolução foi satisfatória em 51,1% e fatal em 31,9%. Conclui-se que a hidrocefalia é mais comum no sexo masculino em idade produtiva, tendo a HIC, CEF, MN e PSI como manifestações freqüentes e que, a necessidade de revisões de DVP, piora o prognóstico.

The 434(G > C) polymorphism in the eosinophil cationic protein gene and its association with tissue eosinophilia in oral squamous cell carcinomas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of temperature on lung and blood gases in the South American rattlesnake Crotalus durissus terrificus

The effects of temperature on lung and blood gases were measured in the South American rattlesnake (Crotalus durissus terrificus). Arterial blood and lung gas samples were obtained from chronically cannulated animals at 15, 25, and 35 degrees C. As expected for reptiles, arterial pH fell with increased temperature (0.018 U degrees C-1 between 15 and 25 degrees C and 0.011 U degrees C-1 between 25 and 35 degrees C) while lung gas PCO2 rose from 5.8 mmHg at 15 degrees C to 13.2 mmHg at 35 degrees C. Concurrently, lung gas PO2 declined from 132 mmHg at 15 degrees C to 120 mmHg at 35 degrees C, and arterial PO2 increased from 33 to 76 mmHg in that temperature range. Arterial haemoglobin O-2 saturation rose from 0.53 at 15 degrees C to 0.83 at 25 degrees C but became slightly reduced (0.77) with a further elevation of temperature to 35 degrees C. Arterial haemoglobin concentration increased from 1.96 to 2.53 mM between 15 and 35 degrees C, consistent with higher demands on oxygen delivery to tissues at elevated temperatures. Moreover, the substantial increase of haemoglobin O-2 saturation between 15 and 25 degrees C conforms to the idea that reduction of the central vascular right-to-left shunt (pulmonary bypass of systemic venous return) is associated with high metabolic demands. (C) 1998 Elsevier B.V. All rights reserved.

The unequal influences of the left and right vagi on the control of the heart and pulmonary artery in the rattlesnake, Crotalus durissus

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Utilização de probiótico e de lactulose no controle de hiperamonemia causada por desvio vascular portossistêmico congênito em um cão

O desvio vascular portossistêmico pode ser congênito ou adquirido nos cães. A enfermidade pode levar a alterações neurológicas decorrentes de encefalopatia hepática e a hiperamonenia é um dos mecanismos implicados na fisiopatologia deste quadro. O tratamento clínico visa a reduzir os níveis séricos de amônia com o uso de antibióticos e lactulose. em humanos com hepatopatias, os probióticos podem ser utilizados para reduzir a hiperamonemia. A resposta clínica e laboratorial de um cão com desvio vascular portossistêmico foi demonstrada com a utilização de lactulose e de probiótico, isoladamente e associados, sendo que a melhor evolução foi obtida na terapia conjunta.

Atelectasia pulmonar em cães durante anestesia geral

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

CHARACTERISTICS OF ARTERIAL-HYPERTENSION IN RESPONSE TO BOLUS INJECTION OF PHENYLEPHRINE IN ATROPINIZED PATIENTS

The changes of arterial pressure promoted by bolus injection of 50 mg phenylephrine (PHE) were studied in 20 atropinized patients (5 normal subjects, 13 patients with mitral valve disease, 1 patient with essential arterial hypertension and 1 patient with hypertrophic cardiomyopathy) submitted to routine catheterism. Patients with aortic valve disease, left ventricular outflow tract obstruction and intracardiac shunt were excluded from the study. All patients were in sinus rhythm, without heart failure. Arterial pressure started to increase at 14.8 +/- 5.4 s (range, 5.6 to 27 s; mean +/- SD) after PHE. There was an increase of 37.8 +/- 16.7 mmHg (range, 12.5 to 70 mmHg) in systolic pressure and of 26.6 +/- 11.1 mmHg (range, 7.5 to 42.5 mmHg) in diastolic pressure. Peak hypertension was attained at 36.6 +/- 16.4 s (range, 10.8 to 64.9 s) and hypertension continued for 176 +/- 92 s (range, 11 to 365 s). Heart rate was 114 +/- 21 bpm before PHE and 111 +/- 21 bpm (P<0.05) after PHE. There were no adverse events associated with intravenous PHE injection in any patient, in accordance with the general view that bolus injection of PHE is a safe and practical maneuver to promote arterial hypertension.

Vagal control of heart rate and cardiac shunts in reptiles: Relation to metabolic state

The vagus is clearly of primary importance in the regulation of reptilian cardiorespiratory systems. Vagal control of pulmonary blood flow and cardiac shunts provides reptiles with an additional means of regulating arterial oxygen levels that is not present in endothermic vertebrates (birds and mammals). Within a given species, there exists a clear correlation between withdrawal of vagal tone on the cardiovascular system and elevated metabolic rate. Undisturbed and resting reptiles are normally characterised by high vagal tone, low pulmonary blood flow and large right-left (R-L) cardiac shunts. The low oxygen levels that result from the large R-L shunt may serve to regulate metabolism. However, when metabolism is increased by temperature, exercise or digestion, the R-L cardiac shunt is reduced, which serves to increase oxygen delivery. This response is partially elicit ed by reduction of vagal tone. Interspecies comparisons reveal a similar pattern. Thus, species that are able to sustain the highest metabolic rates possess the highest degree of anatomical ventricular separation and, therefore, less cardiac shunting. It is interesting to note that when cardiac shunts occur in mammals, due for example to developmental defects, they are associated with reduced maximal metabolic rates and impaired exercise tolerance. It appears, therefore, that full separation of ventricular blood flows was a prerequisite for the evolution of high aerobic metabolic rates and exercise stamina in mammals and birds.

Effect of oxytocin on transepithelial transport of water and Na+ in distinct ventral regions of frog skin (Rana catesbeiana)

Thoracic, abdominal, and pelvic fragments of ventral skin of Rana catesbeiana were analysed regarding the effect of oxytocin on: (1) transepithelial water transport; (2) short-circuit current, (3) skin conductance and electrical potential difference; (4) Na+ conductance, the electromotive force of the Nat transport mechanism, and shunt conductance; (5) short-circuit current responses to fast Na+ by K+ replacement in the outer compartment, and (6) epithelial microstructure. Unstimulated water and Na+ permeabilities were low along the ventral skin. Hydrosmotic and natriferic responses to oxytocin increased from thorax to pelvis, Unstimulated Na+ conductance was greater in pelvis than in abdomen, the other electrical parameters being essentially similar in both skin fragments. Contribution of shunt conductance to total skin conductance was higher in abdominal than in pelvic skin. Oxytocin-induced increases of total skin conductance, Na+ conductance, and shunt conductance in pelvis were significantly larger than in abdomen, An oscillatory behaviour of the short-circuit current was observed only in oxytocin-treated pelvic skins. Decrease of epithelial thickness and increase of mitochondria-rich cell number were observed from thorax to pelvis, Oxytocin-induced increases of interspaces were more conspicuous in pelvis and abdomen than in thorax.