216 research outputs found
Our United States : A Patriotic Hymn
https://digitalcommons.library.umaine.edu/mmb-vp/2345/thumbnail.jp
Synthesis and Optimization of Wind Energy Conversion Devices
An approximate method for the analysis of interaction between wind flow and rigid flat blades is considered. The method allows synthesis and optimization of wind energy conversion systems without using space-time-programming procedures. By this method, the action of wind flow on the blade is subdivided on frontal pressure and vacuum (depression) on leeward side. The method was tested by computer simulation and experiments in wind tunnel. Examples of optimization tasks are solved in application to blades with simple shape. New wind energetic device with controlled orientation of flat blades to air flow is developed. Theoretical and experimental analysis of blade’s interaction with airflow is performed. Aerodynamic coefficients for blade’s drag and lifting forces are determined experimentally in wind tunnel. Optimization of system parameters is made. To increase the efficiency of energy transformation, it is proposed to change, by special law, the orientation of blade’s working surface relative to airflow during rotation of the rotor. It is shown that the optimal angular rotation frequency ratio between rotor and blade is equal to two. Serviceability and main advantages of the proposed method are confirmed by experiments with physical model of airflow device
ASSESSMENT OF RARE EPIPHYTIC LIVERWORT TRANSPLANTATION METHOD IN POPULUS TREMULA FOREST
Epiphytic bryophytes are important biodiversity elements in forest ecosystems globally. In addition, bryophytes take part in ecosystem functioning and are excellent environmental indicators. Almost half of the red-listed bryophyte distribution in Latvia is related to forest habitats. However, despite the increasing knowledge about epiphyte ecology, we are lacking information about individual rare species environmental demands. The present study aimed to evaluate the transplant disc method in rare liverwort transplantation success in aspen forest. As a result, we found that the transplant disc method can be used in epiphytic liverwort studies, but improvements are recommended in sealant selection for transplantation. Liverwort transplants were sensitive to changed substrate quality. Although transplant physiological stress during the transplantation experiment could be important. Epiphyte transplantation studies could help to test epiphyte sensitivity to global climate change in the future
Investigation of dual varying area flapping actuator of a robotic fish with energy recovery
Autonomous under-water vehicles (AUV) performing a commanded task require to
utilize on-board energy sources. At the time when on-board power source runs low during
operation, the vehicle (AUV) is forced to abort the mission and to return to a charging station.
The present work proposes the technique of an energy recovery from surrounding medium. This
effect is studied for dual action actuator movement that obtains energy from fluid. It is realized
that a flapping or vibrating actuator can be used for energy extraction phenomenon apart from the
non-traditional propulsive technique. In the present work a simple dual flapping actuator that can
switch between simple flat plate and perforated plate at extreme end positions (angles) by using
an efficient mechatronic mechanism that would help in overcoming viscous forces of the
operating medium is extensively studied. The main objective of the present article is to develop
a new approach for energy gain and recharge power pack of on-board sources from the
surrounding medium and to create a robotic fish that would work autonomously by using
unconventional drive along with the possibility of energy restoration by using dual varying area
type vibrating actuator. At the time of recharge, the robotic fish would project its tail (actuator)
out of water and use surrounding medium (air) to scavenge the energy. All the equations
describing the process are formed according to classical laws of mechanics. The mechatronic
system is explained and the results obtained are discussed in detail for air as the operating fluid
to scavenge energy
Properties of Populus genus veneers thermally modified by two modification methods: wood treatment technology and vacuumthermal treatment
Due to environmental concerns the use of wood materials is becoming more extensive
and is causing wood supply shortage, therefore the use of Populus genus wood species with a
short rotation period is vital. Populus genus species wood has several shortcomings - it is not
durable, has low density and is hygroscopic. Thermal modification is a technology that can be
used to improve the situation. In this study aspen (Populus tremula L.) was thermally treated
using the Wood Treatment Technology (WTT) device for 50 min at 160 °C (50–160 WTT) and
poplar (Populus x canadensis Moench) was vacuum-treated (VT) 120 min at 204 °C
(120–204 VT), 120 min/ 214 °C (120–214 VT), 180 min 217 °C (180–217 VT) and 30 min
218 °C (30–218 VT). Mass loss (ML), colour change, density, tensile strength along the fibres,
moisture exclusion efficiency and weight loss (WL) after brown rot fungus Coniophora puteana
were determined and also light microscopy images were taken. Aspen veneers showed a ML of
5.3% between 120–214 VT (6.2%) and 30–218 VT (4.6%) treatment that coincided with the same
mass loss in aspen boards cited in the literature. The highest ML was 8.7% calculated from
180–217 VT, while the lowest ML was 2.9% computed from 120–204 VT. The total colour
change ΔE was 44, where lightness parameter L provided the greatest impact that was reduced
twice after modification. Tensile strength reduced by 47% in the WTT process and had ~29%
reduction in the VT process. The WL after fungus C. puteana was 33% at 50–160 WTT. After
VT treatment, WL was 0–2.4%. 120–214 VT and 180–217 VT poplar veneers were the most
suitable for plywood production
Melhoria da Atenção ao Controle e Prevenção dos Cânceres de Colo de Útero e de Mama, na USF Victória, Vacária/ RS
LÓPEZ, Berthalina Irbe. Melhoria da atenção ao controle e prevenção dos cânceres de Colo de útero e de mama, na ESF Victória, Vacaria/ RS. 2015. 63f. Trabalho de Conclusão de Curso (Curso de Especialização em Saúde da Família) - Departamento de Medicina Social, Faculdade de Medicina, Universidade Federal de Pelotas, Pelotas, 2015. A Saúde da Mulher é de grande importância devido aos índices de morbidade e mortalidade por câncer de colo de útero e mama. Em nossa área notamos que muitas mulheres não estavam com seus exames em dia, isso justificou a realização desta intervenção. Tendo como objetivo geral a Melhoria da atenção ao controle e prevenção do câncer de colo do útero e mama na USF Victória, Vacaria/RS durante 12 semanas. Utilizamos uma metodologia organizada e objetiva, que proporcionou conhecer os resultados do trabalho realizado, permitindo identificar as carências e as necessidades, possibilitando organizar por meio dos registros e ficha espelho o acompanhamento adequado das usuárias. Este trabalho foi um esforço coletivo da Equipe Básica de Saúde da USF Victória. Os resultados foram frutos de um trabalho realizado com muito empenho pela equipe de saúde da família, e ao mesmo tempo gratificante pela importância do trabalho e o melhor acompanhamento das usuárias. Apesar de todos os obstáculos encontrados conseguimos atingir alguns objetivos importantes descritos no trabalho, os quais serão aplicados no decorrer do acompanhamento das mulheres trazendo benefícios a população alvo, conseguindo assim realizar uma melhor atenção e prevenção do câncer de mama e do colo de útero. Os resultados alcançados foram cadastradas 148 (13,7%) mulheres entre 25 e 64 anos e 59 (14,9%) das usuárias entre 50 e 69 anos. Dessas 100% tiveram as coletas com amostra satisfatória, nenhum exame alterado do citopatológico e mamografia, quanto aos registros 94,6% das usuárias cadastradas para ca de colo de útero tiveram seus registros completos e 100% das usuárias para ca de mama. Também podemos destacar que todas as cadastradas na intervenção tiveram orientação sobre DSTs e fatores de risco para câncer de colo de útero e mama. A intervenção foi importante para podermos identificar as falhas e tentar conseguir resolutividade nas ações. Para a equipe mostrou-se importante para podemos aprender ainda mais sobre nossa população, desenvolvendo programas de rastreamento na área de saúde. Também foi importante para utilizarmos a intervenção como base para outras ações de saúde desenvolvidas pela equipe de saúde da família. Palavras-chave: atenção primária à saúde; saúde da família; câncer de colo de útero, câncer de colo de mama
CONVEYOR-TYPE SMALL HYDROPOWER PLANT FOR SHALLOW RIVER WATERS
This paper deals with the development of a small conveyor-type hydropower plant intended for operation in shallow river waters without construction of a dam. The proposed design offers a closed-shaped flattened conveyor equipped with flat-shaped blades. The conveyor is oriented perpendicular to the fluid flow. Several identical flat blades interacting with fluid flow are mounted on conveyor belt and move together with the belt in one straight line direction. Then after turning in the reversing mechanism, blades move in the opposite direction. The conveyor system has a built-in energy generator which drive shaft is connected with one of the reversing ends of the plant. Conveyor belt system dynamics analysis is performed on the base of equivalent model with one degree of freedom. The interaction of a moving conveyor flat blade in translation motion with fluid flow is studied by computer simulation with program Mathcad using a superposition principle. In accordance with this approach, a fast-chaotic motion of fluid particles (Brownian motion) is separated from the slow-directed flow motion, with the given average velocity. Optimization of system parameters (blade orientation angle to fluid flow, interaction constants of the braking generator) is performed, using a generated power as criterion. Simulation results confirm the serviceability and operational efficiency of the proposed hydropower plant in shallow river waters.
Livio Rossetti, Le dialogue socratique
J’ai souvent l’impression que dans les domaines tels que les études platoniciennes où l’on ne fait que réfléchir sur les textes anciens qui ont déjà attiré un nombre immense de générations de lecteurs posant les mêmes questions, ce ne sont pas tant les idées ou les hypothèses qui déterminent la qualité d’une approche que la manière dont elles sont exprimées. La recherche du Socrate historique, la volonté de prouver qu’on peut le trouver dans les textes des socratiques si différents les uns de..
Vibration analysis of perforated plate in non-stationary motion
Fluid, non-stationary rigid body interaction is a commonly occurring phenomenon seen in many engineering practices. The article offers a new method using laws of classical mechanics for obtaining simplified analytical relations in analysis and optimisation tasks without using space time programming methods. In the proposed method the fluid space around the rigid body prisms is divided into two zones, pressure and suction (vacuum). The method is extensively discussed which is further extended for calculation of interaction forces and coefficients for non-stationary perforated plate with total area of perforations maintained at half the area of the complete flat plate. Experiments were performed for perforated plate in an Arm-field wind tunnel at constant speed of 10 m/s. The present work offers analysis and synthesis of specific engineering task of energy extraction from fluid in a unique way by making use of external fluid flow over a perforated plate. The fluid is assumed continuous and incompressible
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