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‣ The dependence of effective thermal heat capacity of non-homogeneous materials on location and climatic parameters

Almeida, Manuela; Garcia, Valdemar; Maldonado, Eduardo
Fonte: James & James Publicador: James & James
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
472.20184%
The effective thermal heat capacity of construction materials depends strongly on the external conditions such as solar radiation and ambient air temperatures in contact with those elements. The combination of these factors has not been correctly quantified so far. This work also describes a means for determining the thermal performance of non-homogeneous, multi-layered elements: a detailed numerical method that simulates two-dimensional heat transfer situations that occur in typical Portuguese building construction elements, such as brick walls and slabs, was developed as a tool to quantify effective thermal capacity. Correlations factors between available solar radiation, ambient air temperatures and daily heat capacity were determined for a significant sample of construction elements to permit an easy and quick quantification of thermal heat capacity.

‣ Concreto de alto desempenho aplicado a sistemas de processamento e armazenagem de alimentos em baixas temperaturas; High performance concrete applied to storage and processing system buildings at low temperatures

Lima, Sandra Maria de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 20/10/2008 Português
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381.5182%
O desenvolvimento de um concreto de alto desempenho aplicado a sistemas de processamento e armazenagem de alimentos em baixas temperaturas teve por objetivo atender às indústrias de alimentos no Brasil que se utilizam da tecnologia do frio em seu processo industrial. A hegemonia mundial do mercado de carnes é brasileira, sendo que nossas indústrias são responsáveis por 33% desse mercado. A ausência de estudos para aprimorar e tornar as plantas industriais mais duráveis e condizentes com a importância do setor foi determinante na delineação do tema desta tese. Desenvolveu-se um concreto de alto desempenho frente às possíveis situações em uma planta industrial: baixas temperaturas em ambientes secos e baixas temperaturas em ambientes sujeitos à umidade. A temperatura mínima a qual foram submetidos os concretos analisados foi de 35°C. O método de dosagem e as diretrizes calcadas no reforço da matriz da pasta de cimento e refinamento de poros mostraram-se como uma alternativa para vencer as agressividades causadas pelas baixas temperaturas ao concreto. Até então, estudos sugeriam um sistema de ar cujos vazios teriam diâmetros em torno de 250 µm espaçados com esta mesma distância entre eles e com conteúdo de 6±1% para a proteção de concretos expostos a baixas temperaturas. A produção de um concreto coeso...

‣ Viscoelastic behavior of persimmons dried at constant air temperature

Nicoleti, J. F.; Silveira, V; Telis-Romero, J.; Telis, VRN
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 143-150
Português
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474.99363%
The viscoelastic behavior of dried persimmons at different air-drying temperatures and velocities was evaluated. Air temperatures and velocities were varied according to a second-order central composite design, with temperature ranging from 40degreesC to 70degreesC and air velocity from 0.8 to 2.0 m/s. After drying, persimmons were equilibrated at four different water activities: 0.432, 0.576, 0.625 and 0.751. The rheological behavior of dried and conditioned persimmons was studied under uniaxial compression-relaxation tests. Three different rheological models were fitted to the experimental relaxation curves: Maxwell, Generalized Maxwell and Peleg and Normand. Based on the root mean square of residuals, the Generalized Maxwell model showed the best fit and a regression analysis was applied to obtain response surfaces for the model parameters. The dependence of the rheological properties on water activity was also analysed. Results showed that only the linear effect of air temperature was significant at a 5% level on the equilibrium stress and relaxation times. In a general way, these parameters increased with increasing air temperature and decreasing water activity. (C) 2004 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.

‣ Effects of Irrigation and Tree Spacing on Soil and Air Temperature Profiles of Olive Orchards

Andrade, Josè; Santos, Francisco; Correia, Manuela; Paço, Teresa
Fonte: VIIth International Symposium on Olive Growing Publicador: VIIth International Symposium on Olive Growing
Tipo: Aula
Português
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482.11902%
Changes on the climate of the boundary layer occur when a vegetation cover above a bare soil is introduced, namely on temperatures and humidity profiles, above and under soil surface. Since air and soil temperatures affect crop growth and development and also soil moisture, they have been used as driving variables in numerous crop growth and development models as well as in those referred to soil mineralization, evaporation, transpiration, etc. The aim of this work was to evaluate (a) the soil thermal behavior in two olive orchards (Olea europaea sp. europaea), both grown on soils with little profile development (Regosol and Cambisol) and subject to drip irrigation but with different spacing between trees, and (b) the air thermal profile over olive rows. Experiments were performed from April to June 2012 in Southern Portugal. Soil and air temperatures were measured by thermocouples. The two orchards changed spatial distribution of soil surface temperature, soil temperature profiles and air temperature within the canopy, either on a daily or hourly basis. Olive tree spacing and irrigation affected both the soil thermal behavior and air thermal profiles. Tree spacing affected the horizontal gradients established along the interrows (intensity and rhythm). Irrigation reduced hourly and daily mean soil surface temperatures and daily thermal amplitudes of both profiles. Differences were also found on damping depths of the thermal wave estimated for the driest and the wettest profiles. Along the row...

‣ Productive and morphogenetic responses of buffel grass at different air temperatures and CO2 concentrations

Santos,Roberta Machado; Voltolini,Tadeu Vinhas; Angelotti,Francislene; Aidar,Saulo de Tarso; Chaves,Agnaldo Rodrigues de Melo
Fonte: Sociedade Brasileira de Zootecnia Publicador: Sociedade Brasileira de Zootecnia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 Português
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482.90746%
The objective of the present trial was to evaluate the productive and morphogenetic characteristics of buffel grass subjected to different air temperatures and CO2 concentrations. Three cultivars of buffel grass (Biloela, Aridus and West Australian) were compared. Cultivars were grown in growth chambers at three temperatures (day/night): 26/20, 29/23, and 32/26 °C, combined with two concentrations of CO2: 370 and 550 µmol mol-1. The experimental design was completely randomized, in a 3 × 3 × 2 factorial arrangement with three replications. There were interactions between buffel grass cultivars and air temperatures on leaf elongation rate (LER), leaf appearance rate (LAR), leaf lifespan (LL) and senescence rate (SR), whereas cultivars vs. carbon dioxide concentration affected forage mass (FM), root mass (RM), shoot/root ratio, LL and SR. Leaf elongation rate and SR were higher as the air temperature was raised. Increasing air temperature also promoted an increase in LAR, except for West Australian. High CO2 concentration provided greater SR of plants, except for Biloela. Cultivar West Australian had higher FM in relation to Biloela and Aridus when the CO2 concentration was increased to 550 µmol mol-1. West Australian was the only cultivar that responded with more forage mass when it was exposed to higher carbon dioxide concentrations...

‣ Interaction of air temperature and core temperatures in thermoregulation of the goat.

Jessen, C
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1977 Português
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378.35418%
1. The interaction between air temperature, hypothalamus temperature, and spinal cord temperature in driving heat production and respiratory evaporative heat loss has been studied in conscious goats with chronically implanted thermodes. 2. Thermoregulatory heat production could be described as being approximately proportional to the sum of two linear drives determined by hypothalamus temperature and spinal cord temperature. This was found also for respiratory evaporative heat loss except that it was not influenced by spinal cord cooling. 3. Thermoregulatory heat production could be further described as being approximately proportional to a product of linear drives determined by hypothalamus and spinal cord temperature on one hand and air temperature on the other. Respiratory evaporative heat loss was approximately proportional to the sum of drives determined by spinal cord, hypothalamus and air temperatures. 4. Sensitivity to central cooling was found to undergo long-lasting but temporary changes which interfered with the immediate effects of air temperature on thermoregulation. 5. Central threshold temperatures for heat production and respiratory evaporative heat loss were found to be differently affected by air temperature. This indicates that integrating mechanisms for heat production and respiratory evaporative heat loss are to some extent functionally independent.

‣ Air temperature recordings in infant incubators.

Aynsley-Green, A; Roberton, N R; Rolfe, P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1975 Português
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379.4046%
Air temperatures were continuously recorded inside four incubators with proportional heating control and six incubators with on/off heating cycles, during routine use. The air temperatures in the former were constant throughout, with a gradient between the roof and above-mattress air temperature not exceeding 1 degree C. In contrast, the recordings from the latter models showed a regular cyclical oscillation, the duration of the cycle varying from 14 to 44 minutes. Each incubator had a characteristic profile. The roof air temperature could vary by as much as 7-1 degrees C and the above-mattress air temperature by as much as 2-6 degrees C during the cycle. The oscillation persisted in the air temperatures recorded inside an open-ended hemicylindrical heat shield when used inside these incubators, but was markedly reduced inside a closed-ended heat shield, Carbon dioxide concentration did not increase significantly inside the latter.

‣ Impacts of wind farms on surface air temperatures

Baidya Roy, Somnath; Traiteur, Justin J.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
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463.1766%
Utility-scale large wind farms are rapidly growing in size and numbers all over the world. Data from a meteorological field campaign show that such wind farms can significantly affect near-surface air temperatures. These effects result from enhanced vertical mixing due to turbulence generated by wind turbine rotors. The impacts of wind farms on local weather can be minimized by changing rotor design or by siting wind farms in regions with high natural turbulence. Using a 25-y-long climate dataset, we identified such regions in the world. Many of these regions, such as the Midwest and Great Plains in the United States, are also rich in wind resources, making them ideal candidates for low-impact wind farms.

‣ Characterizing Air Temperature Changes in the Tarim Basin over 1960–2012

Peng, Dongmei; Wang, Xiujun; Zhao, Chenyi; Wu, Xingren; Jiang, Fengqing; Chen, Pengxiang
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 06/11/2014 Português
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380.8875%
There has been evidence of warming rate varying largely over space and between seasons. However, little has been done to evaluate the spatial and temporal variability of air temperature in the Tarim Basin, northwest China. In this study, we collected daily air temperature from 19 meteorological stations for the period of 1960–2012, and analyzed annual mean temperature (AMT), the annual minimum (Tmin) and maximum temperature (Tmax), and mean temperatures of all twelve months and four seasons and their anomalies. Trend analyses, standard deviation of the detrended anomaly (SDDA) and correlations were carried out to characterize the spatial and temporal variability of various mean air temperatures. Our data showed that increasing trend was much greater in the Tmin (0.55°C/10a) than in the AMT (0.25°C/10a) and Tmax (0.12°C/10a), and the fluctuation followed the same order. There were large spatial variations in the increasing trends of both AMT (from −0.09 to 0.43 °C/10a) and Tmin (from 0.15 to 1.12°C/10a). Correlation analyses indicated that AMT had a significantly linear relationship with Tmin and the mean temperatures of four seasons. There were also pronounced changes in the monthly air temperature from November to March at decadal time scale. The seasonality (i.e....

‣ High-Temperature, Forced-Air Quarantine Treatment for Papayas Infested with Tephritid Fruit Flies (Diptera: Tephritidae)

Armstrong, John W.; Hansen, James D.; Hu, Benjamin K. S.; Brown, Steven A.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica Formato: text/html
Português
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380.9227%
A high-temperature forced-air (HTFA) disinfestation treatment using four temperature stages was developed to disinfest Hawaii-grown papaya, Carica papaya L. cv. Solo, of the egg and larval stages of Mediterranean fruit fly, Ceratitis capitata (Wiedemann); melon fly, Dacus cucurbitae Coquillett; and oriental fruit fly, D. dorsalis Hendel. The fourstage treatment forced 43 ± 1, 45 ± 1, 46.5 ± 1, and 49 ± 0.5°C hot air over the papaya surfaces until the fruit center temperatures at the end of each temperature stage reached 41 ± 1.5,44 ± 1,46.5 ± 0.75, and 47.2°C, respectively. Each of the first three temperature stages required about 2 h to heat the fruit to the corresponding fruit center temperatures; the last temperature stage required <1 h to raise the fruit center temperatures to 47.2°C. Relative humidity of 40-60% during treatment prevented fruit damage. When the fruit center temperatures reached 47.2°C, the papayas were immediately hydrocooled until the fruit center temperatures were ≤30°C. Phytotoxicity tests showed that the HTFA treatment was not detrimental to fruit quality. Survival tests with the HTFA treatment until final fruit center temperatures were 43.2, 45.2, or 46.2°C showed little or no survival between 46.2 and 47.2°C for C. capitata...

‣ Impact of Improved Stoves on Indoor Air Quality in Ulaanbaatar, Mongolia

Cowlin, Shannon; Kaufmann, Rachel B.; Edwards, Rufus; Smith, Kirk R.
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Português
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380.22664%
Ulaanbaatar, Mongolia, is the coldest capital city in the world, with average winter low temperatures of -20° Celsius. Many families there live in gers, traditional Mongolian dwellings consisting of a wooden frame beneath several layers of wool felt. In the ger districts of Ulaanbaatar, cooking and heating energy is provided through indoor coal combustion in metal stoves with chimneys, and in wintertime, such stoves may be in use both day and night. Over the last several years, new stove designs with improved fuel efficiencies have been introduced into many homes. To test the impact of the improved stoves on indoor air quality, 24-hour monitoring of particulate matter (PM) and carbon monoxide (CO) was done in 65 Mongolian gers. The primary analyses focused on 58 households, 20 with original (or traditional-type) stoves, 18 with the improved stove type TT-03, and 20 with the improved stove type G2-2000. In addition to indoor pollutant concentrations, information on other relevant factors was collected...

‣ Risk assessment for environmental health in Adelaide based on weather, air pollution and population health outcomes.

Hansen, Alana L.
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2010 Português
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377.85836%
Background: The progression of climate change may have wide ranging and varied implications for population health. Climatologists predict increases in heatwaves, droughts and bushfires for Australia, with health consequences including a potential rise in heatrelated illnesses and adverse effects from increases in some air pollutants. Epidemiological evidence of the impact of temperature extremes and air pollution on morbidity and mortality at the local level is essential to identify site specific characteristics of vulnerable sub-populations and in projections of future scenarios. This study aimed to assess the impact of weather and air pollution on population health outcomes in Adelaide, and to inform decision makers on likely health impacts of climate change. Method: Health outcome, meteorological and air quality data for periods of up to 12 years were used to assess the environmental health impact of heatwaves and air pollution on morbidity in Adelaide. The first part of the study investigated the impact of heatwaves, defined as being three or more consecutive days of maximum temperatures 35°C or above, on hospital admissions, ambulance callouts and emergency department visits using a case series approach. Spatial analytical techniques were used to identify regions at increased risk in the metropolitan area. The second part of the study investigated...

‣ An investigation of cool roofing on urban street canyon air quality

Naidu, M.; Tian, Z.; Medwell, P.; Birzer, C.
Fonte: The Modelling and Simulation Society of Aust & NZ; Australia Publicador: The Modelling and Simulation Society of Aust & NZ; Australia
Tipo: Conference paper
Publicado em //2013 Português
Relevância na Pesquisa
484.77992%
The installation of cool roofing in urban areas is a practical mitigation measure to reduce the Urban Heat Island (UHI) effect and is currently being implemented in many cities around the world to reduce building cooling load demands. The UHI effect results from surface and air temperatures of urban areas being higher than rural areas due to the thermal properties of buildings and reduced vegetative cover. Examples of cool roofs are white vinyl roofs and roofs with reflective coatings. Cool roofs have high albedo (also known as solar reflectivity or solar reflectance) which helps to reflect sunlight and therefore, reduce roof temperatures. Lower roof temperatures result in lower internal temperatures within buildings and this significantly reduces their cooling load. A street canyon is an representative unit of an urban area whereby a street is flanked by two tall buildings on both sides. The aim of this study was to investigate the effect cool roofing has on the air quality within a street canyon. In this project, an idealised street canyon with a street canyon height-to-width ratio of one was created in a Computational Fluid Dynamics (CFD) model which utilises the Renormalization Group (RNG) k-" turbulence model. In order to verify the model’s ability to simulate thermal effects...

‣ Forecasts of Global Temperatures from Statistical Methods and Global Circulation Models

STIPS Adolf; MACIAS MOY DIEGO; GARCIA GORRIZ Elisa
Fonte: University of Trento Publicador: University of Trento
Tipo: Contributions to Conferences Formato: DVD
Português
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382.84625%
During the past five decades, global air temperatures have been warming at a rather high rate (IPCC-2013) resulting in scientific and social concern. This warming trend is observed in field and model data and affects both air temperatures over land and over the ocean. However, the warming rate changes with time and this has led to question the causes underlying the observed trends. Here, we analyze recent measured and modeled data on global mean surface air temperature anomalies (GMTA) covering the last 160 years using spectral techniques. The spectral analysis shows two major signals, a strong secular trend (ST) and a clear multidecadal sinusoidal oscillation (MDV) that resembles the Atlantic Multidecadal Oscillation (AMO). The observed acceleration of the warming during the period from 1970 to 2000 therefore appears to be caused by a superimposition of anthropogenic-induced warming (~60%) with the positive phase of a multidecadal oscillation (~40%). The recent slowdown (hiatus) of this tendency is likely due to a shift in the MDV phase. This change in the MDV phase could mask the effect of global warming in the forthcoming decades and the current hiatus could be already a manifestation of this phenomenon. Most current generation global circulation models (CMIP5) do not reproduce this MDV and are missing the actual temperature hiatus. Therefore...

‣ Novel single-double-effect LiBr-H₂O absorption prototype with a highly efficient direct air-cooled adiabatic absorber: characterization, simulation and experimental results; Nuevo prototipo de máquina frigorífica de absorción de LiBr-H₂O de simple y doble efecto con absorbedor adiabático refrigerado por aire de alta eficiencia : descripción, simulación y resultados experimentales

González Gil, Arturo
Fonte: Universidade Carlos III de Madrid Publicador: Universidade Carlos III de Madrid
Tipo: Tese de Doutorado Formato: application/pdf
Português
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380.8875%
Due to unsustainable growth of air conditioning market, a great interest in solar cooling technologies has emerged. The coincidence between availability of solar irradiation and peaks of cooling demand makes solar cooling a very attractive option to replace conventional refrigeration machines based on electricity. What is more, solar cooling systems normally use natural refrigerants that are not harmful to the environment. However, an improvement of the current technology is needed for solar cooling systems to compete with electricity‐powered air conditioning systems. In this work, a novel air‐cooled single–double‐effect LiBr/H₂O absorption prototype is proposed as a solution to improve the viability of solar cooling systems. This prototype presents the following distinguishing features: firstly, it is directly air‐cooled, which means that no cooling tower is needed; secondly, it is made up by compact heat exchangers, which allows for a reduced size of about 1 m₃; thirdly, it incorporates an adiabatic absorber operating with flat‐fan solution sheets, which permits the working solution not to crystallize at high ambient temperatures; lastly, it can be powered by solar heat in its single‐effect mode (4.5 kW), or by an alternative source such as fuel or waste heat in its double‐effect stage (7 kW). In this way...

‣ Aplicabilidade de sistemas de ventilação com permutador de calor ar-solo no clima português; Applicability of ventilation systems coupled with earth-to-air heat exchanger in Portuguese climate

Sousa, Élio de Castro
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Trabalho de Conclusão de Curso
Publicado em //2014 Português
Relevância na Pesquisa
468.05562%
Dissertação de mestrado integrado em Engenharia Civil; As exigências da sociedade moderna e os seus hábitos estão a transformar o planeta Terra, desgastando os seus recursos naturais e poluindo os solos, a água e a atmosfera. O elevado ritmo de consumo energético, especialmente no sector da construção, tem levado a um intenso estudo de desenvolvimento e à utilização de energias renováveis com o objetivo de reduzi-lo até um nível sustentável. As Diretivas Comunitárias e a legislação portuguesa atualmente em vigor apontam para o aumento da eficiência energética dos edifícios, conseguindo-o através do aumento do isolamento térmico da envolvente, do melhoramento da estanquicidade ao ar dos envidraçados e da implementação de um mínimo horário de renovações do ar interior. No entanto, tem-se verificado que se com o aumento do isolamento da envolvente se conseguem reduzir os fluxos de calor entre o exterior e o interior, com a renovação de ar por hora aumenta-se as necessidades de aquecimento e por vezes de arrefecimento. Neste contexto, a utilização conjunta de sistemas de ventilação convencionais e de permutadores de calor com tubos enterrados no solo, pode trazer benefícios na redução dos consumos energéticos das necessidades de aquecimento e arrefecimento. Nestes sistemas...

‣ Modeling air temperature through a combination of remote sensing and GIS data

Cristóbal Rosselló, Jordi; Ninyerola i Casals, Miquel; Pons, Xavier
Fonte: Universidade Autônoma de Barcelona Publicador: Universidade Autônoma de Barcelona
Tipo: Artigo de Revista Científica Formato: application/pdf
Publicado em //2008 Português
Relevância na Pesquisa
483.60195%
Air temperature is involved in many environmental processes such as actual and potential evapotranspiration, net radiation and species distribution. Ground meteorological stations provide important local data of air temperature, but a continuous surface for large and heterogeneous areas is also needed. In this paper we present a hybrid methodology between Remote Sensing and Geographical Information Systems to retrieve daily instantaneous, mean, maximum and minimum air temperatures (2002–2004) as well as monthly and annual mean, maximum and minimum air temperatures (2000-2005) on a regional scale (Catalonia, northeast of the Iberian Peninsula) by means of multiple regression analysis and spatial interpolation techniques. To perform multiple regression analysis we have used geographical and multiresolution remotely sensed variables as predictors. The geographical variables we have included are altitude, latitude, continentality and solar radiation. As remote sensing predictors, we have selected those variables that are most closely related with air temperature such as albedo, land surface temperature (LST) and NDVI obtained from Landsat-5 (TM), Landsat-7 (ETM+), NOAA (AVHRR) and TERRA (MODIS) satellites. The best air temperature models are obtained when remote sensing variables are combined with geographical variables: averaged R2 = 0.60 and averaged root mean square error (RMSE) = 1.75C for daily temperatures...

‣ Projected Average Summer Air Temperature Increases and the Implications for Philadelphia's Surface Drinking Water Supply

Rockwell, Julia
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Masters' project
Publicado em 05/12/2014 Português
Relevância na Pesquisa
483.60195%
Water managers are faced with numerous uncertainties that need to be addressed in the development of long-term planning initiatives and large-scale investment decisions. One of the primary and perhaps most far-reaching of these uncertainties is climate change. The objective of this project is to utilize one aspect of projected climate change impacts, increasing average summer air temperature, to understand potential impacts to surface drinking water supply temperatures in the Schuylkill River at Philadelphia, PA. The project consists of three major components. As an initial step, climate model output from the Coupled Model Intercomparison Project Phase 5 (CMIP5) was evaluated for the Northeast US and Philadelphia by mapping and analyzing Network Common Data Form (NetCDF) files for near-surface air temperatures in Matlab. The evaluation of climate model output included model validation for six selected CMIP5 Global Climate Models (GCMs), as well as future projections using the Representative Concentration Pathway 8.5 (RCP8.5) climate scenario. Secondly, this project aimed to develop a statistical relationship between air and surface water temperatures in Philadelphia using publicly available data from the United States Geological Survey (USGS) and Daymet. Following the aforementioned empirical analyses...

‣ TEMPERATURES LIMIT FOR WHITE OAT SEED DRYING; TEMPERATURAS LIMITE PARA SECAGEM DE SEMENTES DE AVEIA BRANCA

AHRENS, Dirk Claudio
Fonte: UFPR Publicador: UFPR
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Artigo Avaliado pelos Pares Formato: application/pdf
Publicado em 27/10/2004 Português
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385.26797%
The white oats come being south as option for the winter sowing, having demand for seeds. On the other hand, the technician-scientific informations are reduced, particularly, in relation to the drying operation. Like this the objective were to study the white oat seeds sensibility in relation to the high drying temperatures and to verify the water loss rate in the artificial drying. Three experiments were conducted in the Instituto Agronômico do Paraná (IAPAR), Ponta Grossa – PR, Brazil. In Ocotober of 1997 the experiment 1 was established in oven to evaluate maximum drying temperature for the white oat seeds, cultivar UFRGS 14, without harming the physiological quality. In November of 1997, the experiments 2 and 3 were driven in a commercial dryer, starting from the preliminaries temperatures limits results obtained in the experiment 1. In the experiment 2, the air-drying temperatures were initially low and increasing later, that should allow the fastest seeds drying without affecting physiological quality. In the experiment 3 the seed drying started with elevated high air temperatures. In all experiments, the seed water content was determined during the drying operation by 105ºC + 3ºC oven method. The white oat industrial quality was determined by the industrial performance...

‣ Physical factors and their influence on fish species composition in Asa Lake, Ilorin, Nigeria

Araoye,P.A
Fonte: Revista de Biología Tropical Publicador: Revista de Biología Tropical
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2009 Português
Relevância na Pesquisa
381.9268%
The effect of physical factors on fish species composition was studied during 12 months in Asa Lake, Nigeria. Fish and water samples were collected bimonthly (March 2003 to February 2004) in the morning. Fish samples were caught with gill nets set at the surface and bottom habitats. There were 11 fish families and 21 species. Osteoglossidae, Anabantidae, Channidae, Schilbedae and Cyprinidae were rare and occurred seasonally in fishermen catches, while Mormyridae, Cichlidae, Mochokidae, Characidae, Bagridae and Clariidae showed less variation and were more common. Characidae and Cichlidae were the most abundant (23.0 and 18.6% respectively) while Osteoglossidae, Channidae and Anabantidae were the least (1.7, 2.1 and 2.3% respectively). Clariidae and Mormyridae had the highest weight with 16.0% and 12.3% respectively, while Anabantidae had the lowest (3.4%). Surface water temperatures were generally higher than air temperatures during the afternoon, except from January to March when air temperatures were high (28.1 to 28.7 ºC) due to low relative humidity (39 to 70%). In the morning, surface water temperatures (25.5 to 26.3 ºC) became higher than air temperatures (25.2 to 26.0 ºC) from May to December, when relative humidity values were also high (50 to 88%). The differences between surface and bottom water temperatures was generally higher (0.7 to 3.1 ºC; P < 0.05) in the afternoon (0.2 to 0.8 ºC) due to sunlight. Temperature differences in the surface and bottom waters were usually higher during the dry season (P < 0.05)...