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Numerical Analysis of Turbulent Fluid Flow and Drag Coefficient for Optimizing the AUV Hull design

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Open Journal of Fluid Dynamics 2014年第3期4卷 263-277页

作者： joao victor nunes de sousa Antonio Roberto Lins de Macedo Wanderley Ferreira de Amorim Junior Antonio Gilson Barbosa de Lima department of Mechanical Engineering Center of Sciences and TechnologyFederal University of Campina GrandeCampina GrandeBrazil ARMTEC Technology in Robotics FortalezaBrazil

Autonomous Underwater Vehicles (AUVs) are robots able to perform tasks without human intervention (remote operators). Research and development of this class of vehicles has growing, due to the excellent characteristics of the AUVs to operate in different situations. Therefore, this study aims to analyze turbulent single fluid flow over different geometric configurations of an AUV hull, in order to obtain test geometry that generates lower drag force, which reduces the energy consumption of the vehicle, thereby increasing their autonomy during operation. In the numerical analysis was used ANSYS-CFX® 11.0 software, which is a powerful tool for solving problems involving fluid mechanics. Results of the velocity (vectors and streamlines), pressure distribution and drag coefficient are showed and analyzed. Optimum hull geometry was found. Lastly, a relationship between the geometric parameters analyzed and the drag coefficient was obtained.

关键词： AUV Hull Drag Coefficient Numerical Simulation

On the Study of Autonomous Underwater Vehicles by Computational Fluid-Dynamics

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Open Journal of Fluid Dynamics 2020年第1期10卷 63-81页

作者： joao victor nunes de sousa Antonio Gilson Barbosa de Lima Francisco Alves Batista Edna Cordeiro de Souza Daniel Cesar de Macedo Cavalcante Paulo de Morais Pessoa joao Evangelista Franco do Carmo department of Mechanical Engineering Federal University of Campina GrandeCampina GrandeBrazil department of Physics State University of ParaibaCampina GrandeBrazil department of Physics and Mathematical Federal University of Campina GrandeCampina GrandeBrazil Federal Institute of Education Science and Technology of the Sertao PernambucanoSerra TalhadaBrazil

Autonomous Underwater Vehicles (AUV’s) are considered as advanced classes of vehicles, capable of performing pre-established missions without physical communication with the ground or human assistance. The research and development of this type of vehicles have been motivated, due to its excellent characteristics, ideal to the military, scientific and industrial sectors. Thus, the objective of this paper is to study fluid flow behavior past over AUV’s, without and with control surfaces (rudders), by Computational Fluid-Dynamics (CFD), aiming to obtain information about the impact of the operating depth and control surfaces on the vehicle's hydrodynamics, in order to help researchers and designers of this class of vehicles. Results of the drag coefficient, pressure, velocity and streamlines distribution around the vehicles are presented and analyzed.

关键词： Autonomous Underwater Vehicle Fluid Flow Computational Fluid-Dynamics Drag Coefficient

Analysis of alternative parameters of dynamic resistance measurement in high voltage circuit breakers

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High Voltage 2019年第3期4卷 197-202页

作者： Herbet Filipe dos Santos sousa Adriano Costa de Oliveira George victor Rocha Xavier Henrique nunes de Santana Edson Guedes da Costa Tarso Vilela Ferreira Federal University of Campina Grande Campina GrandeBrazil Federal University of Sergipe AracajuBrazil

Throughout its lifetime,high-voltage circuit breaker(HVCB)contacts suffer from inevitable degradation processes,especially during the formation of electric *** degraded contacts can reduce the current interruption capacity and increase the chances of operational faults,which might lead to considerable financial ***,the use of efficient evaluating techniques is a key factor to achieve systems *** dynamic resistance measurement(DRM)is a technique that can be used to evaluate the degradation level of HVCB'*** stands out from the usual technique,static resistance measurement,by allowing the assessment of both the main contacts and the arcing contacts(ACs).Usually,the mean resistance or the area under the DRM curve is used to estimate the AC ***,DRM is a non-standardised technique and there are no specified parameters to evaluate the real wear ***,an analysis of alternative parameters extractible from the DRM technique is presented in this study,such as amplitude and variance of the DRM *** results attest the possible use of more than one parameter for the continuous evaluation of HVCB ACs,characterising the DRM as a more complete and precise diagnosis tool.

关键词： resistance parameters dynamic

Agave sisalana extract induces cell death in Aedes aegypti hemocytes increasing nitric oxide production

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Asian Pacific Journal of Tropical Biomedicine 2016年第5期6卷 396-399页

作者： Louise Helena Guimaraes de Oliveira Patricia Alexandria Paiva Silva de sousa Fabrine Felipe Hilario Gabriel Joventino Nascimento joao Paulo Saraiva Morais Everaldo Paulo de Medeiros Manoel Francisco de sousa Fabiola da Cruz nunes Biotechnology Center Federal University of Paraiba Embrapa Algodao Brazilian Agricultural Research Corporation

Objective: To investigate the effects of Agave sisalana(A. sisalana) extract on Aedes aegypti(Ae. aegypti) primary cell ***: Cells of Ae. aegypti were exposed to different concentrations of A. sisalana crude extract(0.18–6.00 mg/m L) for 24 h. Then, the cells were labeled with propidium iodide and subjected to fluorescence microscopy to verify cell viability. In addition, nitric oxide production was ***: Results showed that cells exposed to 6 mg/m L of the crude extract presented a greater percentage of death when compared to control(73.8% ± 9.6% vs. 34.6% ± 9.6%).Furthermore, there was an increase in the nitric oxide production in cells exposed to 6 mg/m L of A. sisalana crude extract [(0.81 ± 0.08) mmol/L] compared to control group[(0.41 ± 0.18) mmol/L].Conclusions: The results show that A. sisalana is cytotoxic to Ae. aegypti and may be used as raw material for new eco-friendly and inexpensive insecticides, since sisal industry discards the liquid waste for the extraction of plant fiber.

关键词： Sisal Cell culture Mosquito Insecticide

High efficiency second harmonic generation of nanojoule-level femtosecond pulses in the visible based on BiBO

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High Power Laser Science and Engineering 2019年第1期7卷 82-89页

作者： Mario Galletti Hugo Pires victor Hariton Celso Paiva joao Swen Künzel Marco Galimberti Goncalo Figueira GoLP/Instituto de Plasmas e Fusao Nuclear Instituto Superior Técnico Universidade de Lisboa Central Laser Facility Science and Technology Facilities Council Rutherford Appleton Laboratory Harwell Science and Innovation Campus

We demonstrate high efficiency second harmonic generation(SHG) of near infrared femtosecond pulses using a BiB3 O6 crystal in a single-pass tight focusing geometry setup. A frequency doubling efficiency of 63% is achieved, which is,to the best of our knowledge, the highest value ever reported in the femtosecond regime for such low energy(nJ-level)pumping pulses. Theoretical analyses of the pumping scheme focusing waist and the SHG efficiency are performed, by numerically solving the three wave mixing coupled equations in the plane-wave scenario and by running simulations with a commercial full 3 D code. Simulations show a good agreement with the experimental data regarding both the efficiency and the pulse spectral profile. The simulated SHG pulse temporal profile presents the characteristic features of the group velocity mismatch broadening in a ‘thick' crystal.

关键词： nonlinear process second harmonic generation pumping scheme parametric amplification/oscillators high power laser

Sex and season explain spleen weight variation in the Egyptian mongoose

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Current Zoology 2019年第1期65卷 11-20页

作者： victor BANdeIRA Emilio Virgos Alexandre AZEVEDO joao Carvalho Monica V. CUNHA Carlos Fonseca Dartment of Biology Centro de Estudos do Ambiente e do Mar (CESAM) University of Aveiro Campus Universitario de Santiago Aveiro 3810-193 Portugal departamento de Biologia Geologia Fisica y Qufmica Inorganica Area Biodiversidad y Conservacion Escuela Superior de Ciencias Experimentales y Tecnologia (ESCET) Universidad Rey Juan Carlos c/Tulipan s/n Mostoles Madrid E-28933 Spain Leibniz Institute for Zoo and Wildlife Research Alfred-Kowalke-Straβe 17 Berlin 10315 Germany Instituto de Ciencias Biomedicas Abel Salazar R. Jorge de Viterbo Ferreira 228 Porto 4050-313 Portugal Instituto Nacional de Investigaqao Agraria e Veterinaria (INIAV) IP-National Institute for Agrarian and Veterinary Research Rua dos Lagidos Lugar da Madalena Vairao 4485-655 Portugal cE3c-Centre for Ecology Evolution and Environmental Changes Faculdade de Ciencias Universidade de Lisboa Lisboa 1749-016 Portugal BiolSI-Biosystems & Integrative Sciences Institute Faculdade de Ciencias Universidade de Lisboa Lisboa 1749-016 Portugal Wildlife Ecology & Health group (WE&H) and Servei d'Ecopatologia de Fauna Salvatge (SEFaS) Departament de Medicina i Cirurgia Animals Universitat Autonoma de Barcelona 08193-Bellaterra Barcelona Spain

The Egyptia n mon goose (Herpestes ichneumon Linn aeus, 1758) is a medium-sized car nivore that experienced remarkable geographic expansion over the last 3 decades in the Iberian Peninsula. In this study, we investigated the association of species-related and abiotic factors with spleen weight (as a proxy for immunocompete nee) in the species. We assessed the relationship of body con dition, sex, age, seas on, and envir onmental conditi ons with splee n weight established for 508 hunted specimens. Our results indicate that the effects of sex and season outweigh those of all other variables, including body condition. Spleen weight is higher in males than in females, and heavier spleens are more likely to be found in spring, coinciding with the highest period of investment in reproduction due to mating, gestation, birth, and lactation. Coupled with the absence of an effect of body condition, our findi ngs suggest that splee n weight variation in this species is mostly influe need by lifehistory traits linked to reproduction, rather than overall energy availability, winter immunoenhancement, or energy partitioning effects, and prompt further research focusing on this topic.

关键词： body condition carnivore Herpestes ichneumon Iberian Peninsula mongoose spleen weight

The growth and production modeling of individual trees of Eucalyptus urophylla plantations

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Journal of Forestry Research 2020年第5期31卷 1663-1672页

作者： joao victor Nobre Carrijo Ana Beatriz de Freitas Ferreira Marcela Costa Ferreira Mario Cesar de Aguiar Eder Pereira Miguel Eraldo Aparecido Trondoli Matricardi Alba Valeria Rezende department of Forestry Faculty of TechnologyUniversity of Brası´liaBrası´lia 70910-900Brazil

Individual tree models(ITMs)are classified as growth and production models for projecting current and future forest *** are more complex than other growth and production models,show a higher level of detail and,consequently,produce a better modeling ***,the accuracy and efficiency of ITMs have not been properly assessed to *** this study,we estimated the growth in height,diameter,and individual tree volume of a Eucalyptus urophylla plantation by applying an *** used a continuing forest inventory dataset in which 1554 individual trees within 29 permanent plots were measured in the field over a 6-year period(24 to 72 months).Each individual tree volume was estimated for future tree *** achieve this,we adjusted the model to predict the height and diameter growth,and the probability of mortality as a function of the competition *** ITM accuracy was assessed based on the analysis of variance results and,subsequently,the multiple mean comparison test at the 5%significance *** tree volumes predicted by the ITM for the forest stand aged 72 months,beginning at ages 24,36,48,and 60 months,were compared to the field measured tree volume acquired from the 72-month forest inventory that was used as the reference *** and observed tree volumes were similar when the estimation was based on the 48-month forest *** results might help to reduce financial costs of forest inventory because the ITM produces accurate future predictions of forest stand *** estimated ITM for Eucalyptus plantations using measurement intervals up to 2 years is recommended because it significantly reduced the projected volume discrepancy compared to the field measurements.

关键词： Competition index Forest production Forest site Simulation models Tree mortality

Characterization of blood flow and the effects of exogenous estradiol benzoate on residual follicles formed after ultrasound-guided transvaginal follicle aspiration in cattle

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Journal of Animal Science and Biotechnology 2017年第1期8卷 51-56页

作者： Alberto Mansur Ghetti Luiz Gustavo Bruno Siqueira Eduardo Kenji nunes Arashiro Miller Pereira Palhao Felipe Zandonadi Brandao joao Henrique Moreira Viana Universidade Federal Fluminense Niteroi RJ 24230-340 Brazil Embrapa Gado de Leite Juiz de Fora MG 36038-330 Brazil Universidade Jose do Rosario Vellano Alfenas MG 37130-000 Brazil Embrapa Recursos Geneticos e Biotecnologia PqEB Av. W5 N Brasilia DF 70770-917 Brazil

Background： Removal of the follicular content by ultrasound-guided transvaginal follicle aspiration（TVFA） may fail to induce immediate atresia and loss of function, resulting in the occurrence of residual follicles（RF）. The aims of this study were to characterize the blood flow in RF and to determine the effects of the treatment with estradiol benzoate on RF fate. Lactating, cyclic Holstein-Gir crossbred cows were used. In Experiment 1, follicular wave emergence（D0） was synchronized in cows（n = 10） and follicular growth was then monitored by transrectal ultrasonography from D0 to D8, followed by TVFA of the largest follicle present on the ovaries 24 h later. Color Doppler ultrasound imaging was used to examine blood flow on the follicular wall, which was recorded immediately before and every 12 h after TVFA, up to 72 h. In experiment 2, cows（n = 22） were randomly allocated to receive either 2 mL of saline i.m.（Control group, n = 11） or 2 mL estradiol benzoate i.m.（EB group, n = 11）immediately after TVFA. Ovaries were scanned every 12 h to confirm the presence and to measure the diameter of RF. The contents of the RF, if present, were collected 72 h after the first TVFA, using the same aspiration *** fluid from original follicles and RF were stored at-20 °C until hormonal ***： In Experiment 1, there was no reduction（P 〉 0.05） of blood flow in the remaining follicle walls after TVFA and maximum blood flow values were observed at 49.5 ± 19.7 h post-TVFA. In Experiment 2, formation of RF after TVFA was proportionally similar between Controls（5/9） and EB（5/10） cows. Also, RF diameter did not differ between groups（P 〉 0.05）. Nonetheless, the content of RF from cows in the EB group had lower（P = 0.0004）estradiol（E2） concentration and lower（P = 0.0005） E2：P4 ratio compared with ***： In conclusion, 1） the persistence of vascularization in the remaining follicle wall may contribute to the formation of RF after follicle aspiration,

关键词： Doppler Ovary Ovum pick-up Steroidogenesis Vascularization

Measuring External debt in a Context of Macroeconomic Imbalances

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Journal of Mathematics and System Science 2014年第3期4卷 202-207页

作者： joao Cadete de Matos Ana Margarida de Almeida Ligia Maria nunes Daniela Black Miranda Director Banco de Portugal Statistics Department Lisboa Portugal deputy-Director Banco de Portugal Statistics Department Lisboa Portugal Banco de Portugal Statistics Department Lisboa Portugal

The exploitation of new methodologies and indicators is considered valuable in measuring a key macroeconomic indicator like the external debt. The recent Portuguese economic developments illustrate the need and usefulness of having a multidimensional approach of this indicator, with several balance of payment items, such as the current and the capital account balances, the foreign direct investment or the reserves assets being carefully analysed when reading the external conditions faced by the economy. Only such an approach can provide with a comprehensive measure of external debt consistent across the range of debt instruments, institutional sectors and valuation methods used. This paper develops an assessment of external debt measures and concludes about their potential advantages and disadvantages. Comparisons are made by focusing on alternatives like gross external debt against net external debt, external debt vis-h-vis international investment position, and external debt at nominal value against external debt at market value.

关键词： External debt valuation debt instruments institutional sectors.