Variação estacional da radiação solar em ambiente externo e no interior de floresta semidecídua

Medições diárias de radiação solar global foram feitas, durante o período de junho de 2000 a janeiro de 2001, no interior de mata semidecídua e no ambiente exterior, tendo sido registrados valores médios de 1,1 e 19,3 MJ/m²/d, respectivamente. A transmissão de radiação solar para o interior da mata foi influenciada pela época do ano e variou de 3,3 a 8,2%, para o verão e o inverno. Equações de regressão, para estações do ano, foram desenvolvidas para estimar a radiação solar no interior da mata, em função de valores obtidos no ambiente externo.

Measurement and simulation of solar radiation availability in relation to the growth of coffee plants in an agroforestry system with rubber trees

Solar radiation is an important factor for plant growth, being its availability to understory crops strongly modified by trees in an Agroforestry System (AFS). Coffee trees (Coffea arabica - cv. Obatã IAC 1669-20) were planted at a 3.4 x 0.9 m spacing inside and aside rows of monocrops of 12 year-old rubber trees (Hevea spp.), in Piracicaba-SP, Brazil (22º42'30" S, 47º38'00" W - altitude: 546m). One-year-old coffee plants exposed to 25; 30; 35; 40; 45; 80; 90; 95 and 100% of the total solar radiation were evaluated according to its biophysical parameters of solar radiation interception and capture. The Goudriaan (1977) adapted by Bernardes et al. (1998) model for radiation attenuation fit well to the measured data. Coffee plants tolerate a decrease in solar radiation availability to 50% without undergoing a reduction on growth and LAI, which was approximately 2m².m-2 under this condition. Further reductions on the availability of solar radiation caused a reduction in LAI (1.5m².m-2), thus poor land cover and solar radiation interception, resulting in growth reduction.

MODELING AND SIMULATION OF RELIEF INFLUENCE ON EUCALYPTUS FORESTS: INTERACTION BETWEEN SOLAR IRRADIANCE AND PRODUCTIVITY

ABSTRACT This study aimed to verify the differences in radiation intensity as a function of distinct relief exposure surfaces and to quantify these effects on the leaf area index (LAI) and other variables expressing eucalyptus forest productivity for simulations in a process-based growth model. The study was carried out at two contrasting edaphoclimatic locations in the Rio Doce basin in Minas Gerais, Brazil. Two stands with 32-year-old plantations were used, allocating fixed plots in locations with northern and southern exposure surfaces. The meteorological data were obtained from two automated weather stations located near the study sites. Solar radiation was corrected for terrain inclination and exposure surfaces, as it is measured based on the plane, perpendicularly to the vertical location. The LAI values collected in the field were used. For the comparative simulations in productivity variation, the mechanistic 3PG model was used, considering the relief exposure surfaces. It was verified that during most of the year, the southern surfaces showed lower availability of incident solar radiation, resulting in up to 66% losses, compared to the same surface considered plane, probably related to its geographical location and higher declivity. Higher values were obtained for the plantings located on the northern surface for the variables LAI, volume and mean annual wood increase, with this tendency being repeated in the 3PG model simulations.

Estimativa da irradiação solar global com partição mensal e sazonal para a região de Cascavel - PR

No presente trabalho, mostram-se equações de estimativa da irradiação solar global (R G), por meio do modelo de Angstrom, com partições sazonal e mensal para a região de Cascavel - PR. Os dados experimentais foram cedidos pelo IAPAR, coletados na sua estação meteorológica localizada na COODETEC/Cascavel - PR, no período de 1983 a 1998. Dos 16 anos de dados, 12 anos foram utilizados para cálculo dos coeficientes (a e b) e quatro anos para a validação das equações. Os coeficientes de determinação encontrados foram superiores a 80% para as duas partições. O mínimo da R G é superestimado e o máximo é subestimado quando comparados com o mínimo e o máximo para dados reais, sendo esses encontrados no solstício de inverno e equinócio de primavera, respectivamente. A variação sazonal e mensal do coeficiente "a" foi menor (0,16 a 0,19 e 0,14 a 0,21) e do coeficiente "b" maior (0,34 a 0,43 e 0,32 a 0,44). As maiores variações dos erros médios diários ocorreram no equinócio de primavera (-19,45% a 27,28%) e as menores no equinócio de outono (-11,32% a 10,61%). O ajuste mais eficaz das equações foi encontrado para a partição mensal.

Avaliação de modelo matemático para estimar a radiação solar incidente sobre superfícies com diferentes exposições e declividades

Este trabalho teve por objetivo avaliar modelo matemático para estimar a radiação solar global diária sobre superfícies com diferentes exposições e declividades, no período de março de 2002 a março de 2003. A pesquisa foi desenvolvida em uma estrutura denominada "Bacia Hidrográfica Experimental" do Departamento de Engenharia Rural da UNESP, Câmpus de Jaboticabal - SP. Nessa estrutura, foram utilizadas superfícies caracterizadas como H, 10N, 10S, 20N, 20S, 10E, 10W, 20E e 20W. O sensor utilizado para medir a radiação solar global incidente nas superfícies estudadas foi um piranômetro da marca Kipp & Zonnen, modelo CM3. Para calcular a radiação solar incidente nas superfícies estudadas, foi utilizado o modelo de Kondratyev. As análises dos resultados foram feitas para o período diário, utilizando-se de análise de regressão e considerando o modelo linear (y = ax + b), na qual a variável dependente foi a radiação global medida (K¯M) e a radiação global calculada (K¯C) foi a variável independente. Os resultados deste estudo mostram que o modelo apresentou bons resultados para estimar a radiação nas superfícies H, 10N, 10S, 10E, 10W, 20E e 20W. Utilizando-se de dados de dias com céu límpido, foram obtidos os seguintes resultados: no inverno, o modelo foi preciso para estimar a radiação solar na superfície 20N, e apresentou resultados aceitáveis para estimar a radiação solar na superfície 20S.

Análise de um sistema de aquecimento de água para residências rurais, utilizando energia solar

A conscientização da importância do meio ambiente tem incentivado o estudo de novas fontes energéticas renováveis e menos poluentes. Dentre essas fontes, a energia solar destaca-se por ser perene e limpa. A utilização da energia solar em sistemas de aquecimento de água residencial rural pode colaborar com a economia de energia elétrica, base da matriz energética brasileira. Conhecer os fatores que influenciam na operação de um sistema de aquecimento de água por energia solar é importante na determinação de sua viabilidade técnica, visando a sua difusão em residências rurais. Para tanto, construiu-se um protótipo, no câmpus da Faculdade Assis Gurgacz, em Cascavel - PR, com características similares a um equipamento utilizado em residências para dois habitantes, para funcionar com circulação natural ou termossifão e sem auxílio de sistema de aquecimento complementar. O equipamento mostrou-se viável tecnicamente, alcançando a temperatura mínima para banho de 35 °C, sempre que a radiação solar foi superior a 3.500 Wh m-2, o que aconteceu para a maioria dos dias estudados.

Evapotranspiração de referência com base na radiação solar global estimada pelo método de Bristow-Campbell

A quantidade de água a ser aplicada em sistemas de irrigação é normalmente calculada com base na evapotranspiração de referência (ETo) da região. Vários métodos podem ser empregados para o cálculo de ETo, sendo o de Hargreaves um dos mais adotados. Esse método utiliza valores estimados da radiação solar global (Rs) com base na diferença entre as temperaturas máxima (Tmáx) e mínima (Tmín) do ar. Entretanto, a Rs pode ser calculada por outros métodos, como o de Bristow-Campbell, que também se baseia na diferença entre Tmáx e Tmín. No presente trabalho, foram estimados valores diários da ETo pelo método de Hargreaves, em Jales - SP, com e sem o uso da equação de Bristow-Campbell para cálculo de Rs. Esses valores foram comparados aos obtidos pelo método de Penman-Monteith, que é considerado padrão para a estimativa de ETo. As avaliações consideraram os períodos úmido e seco na região. O uso da equação de Bristow-Campbell melhorou o desempenho do método de Hargreaves, em relação ao de Penman-Monteith, sendo que durante o período seco do ano o desempenho foi superior ao do período úmido.

Solar drying of jack fruit almonds

Dryers heated by solar energy have been constructed and used in drying whole and half jack fruit almonds. The samples were dried during the day in direct sun and in the conventional solar dryer prepared for this purpose. Another piece of equipment was built for reception and accumulation of sun energy in a body of water, which was used as a heat source for night drying. The drying with the sun energy was compared with artificial drying. The jack fruit almonds were dried whole, half, with pellicle and without it. The storage of solar energy in water was technically viable for use in night drying. The drying by combining solar dryers in the day and night periods were completed in approximately 35 hours, and were equivalent to artificial drying between 40ºC and 70ºC. Almond cut in half and the pellicle removed reduced the drying time.

Computer tools applied to analysis of solar water heaters

The simulation programs are important tools to analyze the different energetic alternatives, including the use of renewable energy. The objective of this study was to analyze comparatively the different computer tools available for modeling of solar water heaters. Among the main simulation software of solar thermal systems, there are: RETScreen International, EnergyPlus, TRNSYS, SolDesigner, SolarPro, e T*SOL. Among the tools mentioned, only EnergyPlus and RETScreen International are free, but they allow obtaining interesting results when applied together. The first one has a detailed module of energy analysis of solar water heaters, while the second one provides an detailed economic feasibility study and an assessment of emissions of greenhouse gases. RETScreen International and EnergyPlus programs are aimed at a diverse audience, including designers, researchers and energy planners.

Solar energy use for water pre-heating in boilers of agro-industries

Energy consumption in the world has been growing every year. The industrial sector represents 27.32% of the world energy demand. Heating systems that use solar energy may contribute with a percentage of the total energy required by industries. This work aimed to study the use of vacuum solar collectors for water pre-heating in boilers. We used four collectors installed according to NBR 15,569; water flow through the tubes was 0.058 L/s, and temperature in the inlet and outlet pipes was measured. Results showed that instantaneous radiation, and inlet fluid and room temperatures are variables that influence the process, reaching water maximum temperature in the solar collector outlet of 97.9 °C, and efficiency of approximately 65% for most experiments. For the financial viability evaluation, the payback study was applied, which resulted in 4; 7 and 5 years, for the respective sources: firewood, LPG (liquefied petroleum gas), and electricity. Regarding the calculation of the annual contribution to the reduction of greenhouse gases, it was, respectively, 2.162 and 356 kg of CO2 per m² of collector tubes, in comparison with firewood and LPG.

Série histórica secular de brilho solar e suas relações com os modos de variabilidade ENOS e ODP em Santa Maria-RS

Os objetivos neste trabalho foram testar a homogeneidade, recalcular a média climatológica e determinar possíveis tendências e variabilidade interanual e interdecadal na série histórica secular mensal e sazonal de brilho solar, em Santa Maria - RS. Os dados de brilho solar foram obtidos na Estação Climatológica Principal (ECP) do Instituto Nacional de Meteorologia (8o DISME), no período de 1912 a 2011. Foram usados os testes de Sequência, de Mann-Kendall e Pettitt para análise de homogeneidade e tendência, respectivamente. As séries históricas na escala mensal e sazonal são estacionárias e homogêneas, exceto para o mês de dezembro e para a estação de outono. Há variabilidade interanual e interdecadal nas séries, devido aos fenômenos El Niño-Oscilação Sul (ENOS) e da Oscilação Decadal do Pacífico (ODP), com sinal marcante da fase fria de ambos os fenômenos, que aumentam o brilho solar, principalmente nos meses de outubro e novembro (primavera).

Influência da vazão de água sobre o rendimento de um coletor solar plano construído em termoplástico

ResumoAvaliou-se o rendimento térmico de um coletor solar plano construído em termoplástico, em condições reais de operação, registrando as temperaturas de entrada e de saída de água na placa, mediante quatro distintas vazões mássicas de água: 0,026 kg s-1; 0,04 kg s-1; 0,054 kg s-1; e 0,068 kg s-1. Os ensaios foram realizados no Laboratório de Termodinâmica e Energia da Faculdade de Engenharia Agrícola da Unicamp. Com base nos valores de temperatura da água na entrada e na saída das placas, foram calculados os valores de potência térmica [W m-2]. O maior valor médio diário de potência térmica (753 W m-2) foi obtido para a vazão de 0,054 kg s-1. Para a maior vazão (0,068 kg s-1), o valor de potência térmica foi similar ao obtido para a vazão de 0,04 kg s-1 (715 W m-2), mostrando a existência de uma vazão ótima de operação.

Spraying systems and traveling speed in the deposit and spectrum of droplets in cotton plant

ABSTRACT Tractor traveling speed can influence the quality of spraying depending on the application technology used. This study aimed to evaluate the droplet spectrum, the deposition and uniformity of spray distribution with different spraying systems and traveling speeds of a self-propelled sprayer in two phenological stages of the cotton plant (B9 and F13). The experimental design was randomized blocks and treatments were three spraying techniques: common flat spray tips; tilted flat jet with air induction, at 120 L ha-1; and rotary atomizer disk, 20 L ha-1, combined with four traveling speeds: 12, 15, 18 and 25 km h-1, with four replications. Spraying deposition was evaluated for both leaf surfaces from the cotton plant apex and base (stage B9) and middle part of the plant (stage F13) with a cupric marker. A laser particle analyzer also assessed the droplet spectrum. The centrifugal power spray system produces more homogeneous droplet spectrum and increased penetration of droplets into the canopy in both phenological stages. Variation on the operating conditions necessary for increased traveling speed negatively influences the pattern of spraying deposits.

Photoexcitation dynamics in organic solar cell donor/acceptor systems

Solceller presenteras ofta som ett miljövänligt alternativ för energiproduktion. Det största hindret för en bredare ibruktagning av kiselbaserade solceller är deras höga pris. I och med upptäckten av ledande och halvledande organiska (kolbaserade) molekyler och polymerer har ett nytt forskningsområde, organisk elektronik, vuxit fram. Den stora fördelen med organisk elektronik är att de använda materialen oftast är lösliga. Tillverkning av elektroniska komponenter kan då göras med hjälp av konventionella trycktekniker där bläcket ersatts med upplösta organiska material. Detta har potential att betydligt sänka priset för solceller. Nackdelen med organisk elektronik är att de använda materialen är komplexa, och de fysikaliska processerna i dem likaså. I min avhandling har jag studerat fotofysiken i två polymerer, P3HT och APFO3, som kan användas för att tillverka organiska solceller. Blandade med fullerenderivatet PCBM, som är en stark elektronacceptor, fås ett material som effektivt producerar elektroner och hål under belysning. I praktiken bidrar dock inte alla skapade laddningar till strömmen ur solcellen. Elektronerna och hålen kan förbli bundna till varandra i olika exciterade tillstånd, och även de som är fria kan träffa på motsatta laddningar under vägen till kontakterna och rekombinera. Centralt i mitt arbete har varit att identifiera olika typer av exciterade tillstånd i dessa solcellsmaterial, samt att bestämma deras livstider och rekombination. Metoden för detta har varit s.k. fotoinducerad absorption, som mäter fotoexcitationernas absorptioner i infraröda våglängdsområdet. De två viktigaste resultaten som presenteras i avhandlingen är en ratekvationsmodell för fotoexcitationsdynamiken i APFO3 på ultrasnabba tidsskalor (femtosekund - microsekund) och bildandet av en rekombinationshämmande dipol vid gränsytan för P3HT och PCBM som följd av värmebehandling. Dessa resultat bidrar till förståelsen av de fotofysikaliska processerna i relaterade material.

Fetal alcohol spectrum disorders in Finnish children and adolescents : diagnosis, cognition, behavior, adaptation and brain metabolic alterations

Alcohol consumption during pregnancy can potentially affect the developing fetus in devastating ways, leading to a range of physical, neurological, and behavioral alterations most accurately termed Fetal Alcohol Spectrum Disorders (FASD). Despite the fact that it is a preventable disorder, prenatal alcohol exposure today constitutes a leading cause of intellectual disability in the Western world. In Western countries where prevalence studies have been performed the rates of FASD exceed, for example, autism spectrum disorders, Down’s syndrome and cerebral palsy. In addition to the direct effects of alcohol, children and adolescents with FASD are often exposed to a double burden in life, as their neurological sequelae are accompanied by adverse living surroundings exposing them to further environmental risk. However, children with FASD today remain remarkably underdiagnosed by the health care system. This thesis forms part of a larger multinational research project, The Collaborative Initiative on Fetal Alcohol Spectrum Disorders (the CIFASD), initiated by the National Institute of Alcohol Abuse and Alcoholism (NIAAA) in the U.S.A. The general aim of the present thesis was to examine a cohort of children and adolescents growing up with fetal alcohol-related damage in Finland. The thesis consists of five studies with a broad focus on diagnosis, cognition, behavior, adaptation and brain metabolic alterations in children and adolescents with FASD. The participants consisted of four different groups: one group with histories of prenatal exposure to alcohol, the FASD group; one IQ matched contrast group mostly consisting of children with specific learning disorder (SLD); and two typically-developing control groups (CON1 and CON2). Participants were identified through medical records, random sampling from the Finnish national population registry and email alerts to students. Importantly, the participants in the present studies comprise a group of very carefully clinically characterized children with FASD as the studies were performed in close collaboration with leading experts in the field (Prof. Edward Riley and Prof. Sarah Mattson, Center for Behavioral Teratology, San Diego State University, U.S.A; Prof. Eugene Hoyme, Sanford School of Medicine, University of South Dakota, U.S.A.). In the present thesis, the revised Institute of Medicine diagnostic criteria for FASD were tested on a Finnish population and found to be a reliable tool for differentiating among the subgroups of FASD. A weighted dysmorphology scoring system proved to be a valuable additional adjunct in quantification of growth deficits and dysmorphic features in children with FASD (Study 1). The purpose of Study 2 was to clarify the relationship between alcohol-related dysmorphic features and general cognitive capacity. Results showed a significant correlation between dysmorphic features and cognitive capacity, suggesting that children with more severe growth deficiency and dysmorphic features have more cognitive limitations. This association was, however, only moderate, indicating that physical markers and cognitive capacity not always go hand in hand in individuals with FASD. Behavioral problems in the FASD group proved substantial compared to the typically developing control group. In Study 3 risk and protective factors associated with behavioral problems in the FASD group were explored further focusing on diagnostic and environmental factors. Two groups with elevated risks for behavioral problems emerged: length of time spent in residential care and a low dysmorphology score proved to be the most pervasive risk factor for behavioral problems. The results underscore the clinical importance of appropriate services and care for less visibly alcohol affected children and highlight the need to attend to children with FASD being raised in institutions. With their background of early biological and psychological impairment compounded with less opportunity for a close and continuous caregiver relationship, such children seem to run an especially great risk of adverse life outcomes. Study 4 focused on adaptive abilities such as communication, daily living skills and social skills, in other words skills that are important for gradually enabling an independent life, maintain social relationships and allow the individual to become integrated into society. The results showed that adaptive abilities of children and adolescents growing up with FASD were significantly compromised compared to both typically-developing peers and IQ-matched children with SLD. Clearly different adaptive profiles were revealed where the FASD group performed worse than the SLD group, who in turn performed worse than the CON1 group. Importantly, the SLD group outperformed the FASD group on adaptive behavior in spite of comparable cognitive levels. This is the first study to compare adaptive abilities in a group of children and adolescents with FASD relative to both a contrast group of IQ-matched children with SLD and to a group of typically-developing peers. Finally, in Study 5, through magnetic resonance spectroscopic imaging (MRS) evidence of longstanding neurochemical alterations were observed in adolescents and young adults with FASD related to alcohol exposure in utero 14-20 years earlier. Neurochemical alterations were seen in several brain areas: in frontal and parietal cortices, corpus callosum, thalamus and frontal white matter areas as well as in the cerebellar dentate nucleus. The findings are compatible with neuropsychological findings in FASD. Glial cells seemed to be more affected than neurons. In conclusion, more societal efforts and resources should be focused on recognizing and diagnosing FASD, and supporting subgroups with elevated risk of poor outcome. Without adequate intervention children and adolescents with FASD run a great risk of marginalization and social maladjustment, costly not only to society but also to the lives of the many young people with FASD.