RESUMO
Mango stone is an interesting biomass by-product with a considerable net calorific value. Mango production has significantly risen in the last few years, meaning that mango waste has increased as well. However, mango stone has a moisture content of about 60% (wet basis) and it is very important to dry the samples for using them in electrical and thermal energy production. In this paper, the main parameters involved in the mass transfer during drying are determined. Drying was carried out in a convective dryer through a set of experiments based on five drying air temperatures (100 °C, 125 °C, 150 °C, 175 °C and 200 °C) and three air velocities (1 m/s, 2 m/s and 3 m/s). Drying times ranged between 2 and 23 h. The drying rate was calculated from the Gaussian model whose values ranged from 1.5·10-6 to 6.3·10-4 s-1. Effective diffusivity was obtained as an overall parameter in the mass diffusion for each test. These values were found between 0.71·10-9 and 13.6·10-9 m2/s. The activation energy was calculated from the Arrhenius law for each test, made at different air velocities. These values were 36.7, 32.2 and 32.1 kJ/mol for 1, 2 and 3 m/s, respectively. This study provides information for future works on design, optimization and numerical simulation models in convective dryers for standard mango stone pieces according to industrial drying conditions.
Assuntos
Mangifera , Biomassa , Dessecação , Difusão , TemperaturaRESUMO
The energy required for various processes in the water cycle can have significant economic and environmental impacts. Therefore, efficient energy management in urban water supply systems is crucial for a sustainable operation. By installing energy recovery technologies in these facilities, it is possible to reap the benefits of the infrastructure design by saving energy. In this study, a new methodology to assess the energy recovery at the inlets of district metered areas is presented, considering the city of Murcia (Spain) as case study. This methodology is based on creating a detailed model of city water supply system and calibrating such model with an experimental campaign of measurements. Then, the assessment of the hydraulic potential recovery is analysed through two different energy estimators, one considering the minimum available net head and the other assuming a variable net head. Results show that there are several points where turbines could be installed, most of them recovering in between 1000-5000 kWh, which could be used to cover the yearly energy consumption of about 24-120 m2 of a school or 10-50 traffic lights of such area. Moreover, in some points it could be recovered up to 14500 kWh. Even though these values are not high, the energy recovered could be used for self-consumption of nearby electrical loads, at the time that reduces the pressure in the system, thus leading to leak reductions. Moreover, this kind of energy recovery does not reduce the potential of other proposals for upstream energy recovery, such as replacing pressure reduction valves with turbines instead. The scripts developed to apply the proposed methodology are available in EPANET-Octave file exchange for the researcher community.
Assuntos
Purificação da Água , Água , Baías , Abastecimento de Água , Meio Ambiente , Purificação da Água/métodosRESUMO
BACKGROUND: Pitchers may be at greater risk of injury in comparison to other overhead throwing athletes due to the repetition of the pitching motion. It has been reported that approximately 30% of all baseball injuries occur in the lower body. This may be related to limited hip mobility, which can compromise pitching biomechanics while placing excessive stress on the trunk and upper quarter. Hip motion and strength measurements have been reported in professional baseball pitchers but have not been reported in collegiate pitchers. PURPOSE: The purpose of this study was to report preliminary findings for passive hip motion and isometric hip muscle strength in collegiate pitchers and compare them to previously published values for professional level pitchers. STUDY DESIGN: Cross sectional study. METHODS: Twenty-nine collegiate baseball pitchers (age = 20.0 + 1.4 years, height = 1.88 + 0.06 m; weight = 89.3 + 10.7 kg; body mass index = 25.3 + 2.5 kg/m2) were recruited. Subjects were assessed for hip internal rotation (IR) and external rotation (ER) passive motion, hip anteversion or retroversion, gluteus maximus, gluteus medius, hip internal rotator, hip external rotator strength, and lumbo-pelvic control with the prone active hip rotation test as described by Sahrmann. Statistical analysis included calculation of subject demographics (means and SD) and use of a two-tailed t-test (p >0.05). RESULTS: Fifty-two percent of the right-handed and 50% of the left-handed pitchers demonstrated poor lumbo-pelvic motor control with an inability to stabilize during active hip IR and ER even though isolated strength deficits were not detected at a significant level. There were no significant differences in hip passive motion or gluteus medius strength between right and left-handed pitchers. Differences did exist between collegiate data and previously published values for professional pitchers for IR motion measured in prone and gluteus maximus strength. Hip retroversion was present in 55% of the pitchers primarily in both limbs with four of the pitchers presenting with retroversion singularly in either the stride or trail limb where the ER rotation motion was greater than the IR. CONCLUSION: Assessing mobility and muscle strength of the lower quarter in isolation can be misleading and may not be adequate to ensure the potential for optimal pitching performance. These findings suggest that lumbo-pelvic control in relation to the lower extremities should be assessed as one functional unit. This is the first study to explore hip motion, strength, and lumbo-pelvic control during active hip rotation in collegiate baseball pitchers. EVIDENCE LEVEL: 2.
RESUMO
An approach to control integrating processes with elevated deadtime using a Smith predictor sliding mode controller is presented. A PID sliding surface and an integrating first-order plus deadtime model have been used to synthesize the controller. Since the performance of existing controllers with a Smith predictor decrease in the presence of modeling errors, this paper presents a simple approach to combining the Smith predictor with the sliding mode concept, which is a proven, simple, and robust procedure. The proposed scheme has a set of tuning equations as a function of the characteristic parameters of the model. For implementation of our proposed approach, computer based industrial controllers that execute PID algorithms can be used. The performance and robustness of the proposed controller are compared with the Matausek-Micic scheme for linear systems using simulations.
RESUMO
El objetivo de este trabajo es determinar el perfil del alumnado de Medicina de la Universidad de buenos Aires y los factores personales que estadísticamente modifican su rendimiento...El resultado fue que el perfil de la población que estudia medicina en la UBA es joven, soltero, no trabaja, domina otros idiomas e informática.A medida que pasan los años por encima de los 25, se observó un marcado alargamiento de los años de la carrera y No. de aplazos. Esta situación se vió agravada en el sexo masculino, los alumnos casados, con hijos y trabajando para sostener sus estudios.Como conclusión, el cumplimiento exitoso de la carrera de Medicina depende de la edad <25 años, el estado civil y el sostén económico.Sin embargo, la crisis de la enseñanza no es un problema sencillo. compromete a docentes, alumnos y medios en que se dicta
Assuntos
Motivação , Estudantes de Medicina , Educação de Graduação em Medicina , Estudos ProspectivosRESUMO
Se contribuye a la casuística con la presentación de 2 casos de angiosarcoma radioinducido, diagnosticados ambos, en pacientes de sexo femenino que previamente habían recibido dosis total de radioterapia, uno por presentar un linfoma tipo Hodgkin, y otro por carcinoma ductal de mama. En una de las pacientes el tiempo de latencia fue de 10 años, mientras que en la otra fue de 25 años. La evolución fue dispar, ya que mientras una tiene un año de evolución sin evidencias de enfermedad, la otra falleció debido a metástasis pulmonares y complicaciones cardíacas al año de ser operada
Assuntos
Humanos , Feminino , Adulto , Idoso , Neoplasias da Mama/radioterapia , Hemangiossarcoma/etiologia , Linfoma não Hodgkin/radioterapia , Quimioterapia Adjuvante , Evolução Clínica , Hemangiossarcoma/complicações , Hemangiossarcoma/diagnóstico , Hemangiossarcoma/cirurgia , Metástase Neoplásica , Radioterapia/efeitos adversosRESUMO
Se analiza la viabilidad del colgajo musculocutáneo de platisma como alternativa en la reconstrucción de partes blandas, post resecciones oncológicas de boca y orofaringe y como coberturas por defectos cutáneos de cabeza y cuello. Con tal fin se realizaron 29 colgajos para reconstruir la cavidad oral en 21 oportunidades, la orofaringe en 4 y como cobertura en otras 4. Se presentaron 8 complicaciones menores, 2 dehiscencias parciales, 2 epidermolisis de menos del 25 por ciento y 4 de más del 50 por ciento. En 3 casos -10,34 por ciento- hubo necrosis total del colgajo. Se destaca como ventaja la proximidad al lugar de la resección, su delgadez, ausencia de pelos, el no requerimiento de aparatología especializada, el reducido tiempo operativo y los excelentes resultados cosméticos y funcionales. No se aconseja realizarlo en cuellos irradiados, de escaso panículo adiposo, previamente operados, o cuando se requiera un vaciamiento radical de cuello.
Assuntos
Humanos , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Cirurgia Plástica/métodos , Retalhos Cirúrgicos/métodos , Neoplasias de Cabeça e Pescoço/cirurgia , Resultado do Tratamento , Cirurgia Bucal/métodos , Retalhos Cirúrgicos/efeitos adversos , Retalhos Cirúrgicos/normas , Soalho Bucal/cirurgia , Neoplasias Bucais/reabilitação , Neoplasias Bucais/cirurgiaRESUMO
Antecedentes: La cirugía craneofacial tiene por objeto la exéresis completa de todos los tumores que en forma presunta o confirmada invaden la base del cráneo, ya sea por una lesión facial que progrese en sentido craneal o de un tumor encefálico que lo haga caudalmente. Objetivo: Comunicar resultados, costo-beneficio y calidad de vida alcanzada. Lugar de aplicación: Hospital público terciario especializado en el tratamiento de tumores. Diseño: Prospectivo. Población: 42 operaciones en 39 enfermos, 61 por ciento masculinos. La localización fue mayor en seno maxilar y etmoides. La patología fue maligna en el 94,8 por ciento. El 35,9 por ciento era virgen de tratamiento. Método: Cirugía sólo del primario en 90,4 por ciento, extendida a órbita en el 30,9 por ciento y al cuello en el 9,5 por ciento. En el 69 por ciento fueron anteriores y en el resto laterales. En 17 operaciones fue necesario algún procedimiento reconstructivo de partes blandas. Resultados: Se produjeron complicaciones en el 59,5 por ciento. La más frecuente fue la supuración local, seguida de la pérdida de LCR. El 50 por ciento de la muestra tuvo la posibilidad de estar vivo a los 27,5 meses. Los costos alcanzaron una media de $4698. La calidad de vida mejoró en el 55 por ciento. Conclusiones: La cirugía craneofacial es un procedimiento sencillo, económico, seguro y efectivo para tratar estos enfermos