Η εργασία αυτή ασχολείται κατά πρώτον με την στατιστική επεξεργασία πεντάλεπτων μετρήσεων φυσικού φωτισμού κατά τη διάρκεια ενός έτους και την παραγωγή διαγραμμάτων μέσων ωριαίων μηνιαίων τιμών για κάθε τύπο καιρού και για κάθε μέγεθος (ολικός φωτισμός, διάχυτος φωτισμός, ολική ηλιακή ακτινοβολία, διάχυτη ηλιακή ακτινοβολία) και κατά δεύτερον με τη δικτύωση μελλοντικών σταθμών στην Αττική (με ενσύρματο ή ασύρματο τρόπο) που μετρούν το φυσικό φωτισμό. / --

With the ever-growing energy demand that world is currently going through and the danger of climate change around the corner, wagering in renewable energy seems to be the right path to create a more smart and green future. Sweden has put great effort on decreasing its dependency on oil, in fact in 2012 more than 50 % of its electricity came from the renewable source and has a plan in making it 100 % in 2040. However, when it comes to heating systems Sweden depends greatly on district heating, and situations which buildings are located outside the district heating system’s reach is not uncommon, hence for those buildings, other options such as solar power or heat pumps are considered. Many buildings located in Skutskär suffer from the problem stated above. The particular building analyzed in this thesis uses electrical radiator and furnace as sources of heat, which implies high energy uses and financial expenses. For this reason technical and financial analysis of using each alternative system for a single family house located in Skutskär had been done. Using solar powered system is deemed to be quite ineffective, as Sweden has poor solar radiation. In order to compensate the poor sun hours during the winter, 51 photovoltaic (PV) panels or 19 solar thermal panels would be required. This high initial investment needs long period of time in order to be profitable, 15 years for solar thermal system and 21 years for solar PV system. On the other hand, the results from the heat pumps are quite satisfactory, the fastest payback period is around 4 years. This is achieved by using air source heat pump (ASHP), the annual saving in this case is three times higher than using solar photovoltaic panels, making the usage of ASHP more attractive than any solar energy system. However, when annual saving is concerned, the ground source heat pump (GSHP) system is capable of generating even higher saving, but the initial investment is significantly higher, extending the payback period to 6 years.

No description available.

No description available.

Solar energy is widely used for electricity generation, heating systems, and indoor environment daytime illumination. Indeed, large amounts of Sunlight energy remain insufficiently used. In this work, we aim at employing sunlight for data transmission as another option for wireless communications. Being emitted by an uncontrollable source, taming the Sunlight is a challenging task that requires appropriate technolo- gies to manipulate incident light. Throughout this thesis, we first review switchable glass technologies and investigate their potential use for light modulation. Liquid Crystal Devices (LCD) have adequate response time and contrast characteristics for such an application. In this regard, we design a novel Dual-cell Liquid Crystal Shutter (DLS) by stacking two Liquid Crystal cells that operate in opposite manners, and we build our Sunlight modulator with an array of DLSs. Then, we adopt Time Division Multiplexing and polarization-based modulation to boost the data rate and eliminate the flickering effect. In addition, we provide mathematical modeling of the system and study its performance in terms of communication and energy consumption. Finally, we introduce some numerical results to examine the impact of multiple parameters on the system’s performance and compare it with state-of-the-art, which showed that our system features higher data rates and extended link ranges.

The chemical reaction of the first excited electronic state of molecular nitrogen, N₂(A), with ground state atomic oxygen is an important contributor to thermospheric nitric oxide (NO).  The importance is assessed by including this reaction in a one-dimensional photochemical model.  The method is to scale the photoelectron impact ionization rate of molecular nitrogen by a Gaussian centered near 100 km. Large uncertainties remain in the temperature dependence and branching ratios of many reactions important to NO production and loss. Similarly large uncertainties are present in the solar soft x-ray irradiance, known to be the fundamental driver of the low-latitude NO.  To illustrate, it is shown that the equatorial, midday NO density measured by the Student Nitric Oxide Explorer (SNOE) satellite near the Solar Cycle 23 maximum can be recovered by the model to within the 20% measurement uncertainties using two rather different but equally reasonable chemical schemes, each with their own solar soft-xray irradiance parameterizations.  Including the N₂(A) changes the NO production rate by an average of 11%, but the NO density changes by a much larger 44%.  This is explained by tracing the direct, indirect, and catalytic contributions of N₂(A) to NO, finding them to contribute 40%, 33%, and 27% respectively. The contribution of N₂(A) relative to the total NO production and loss is assessed by tracing both back to their origins in the primary photoabsorption and photoelectron impact processes.  The photoelectron impact ionization of N₂ is shown to be the main driver of the midday NO production while the photoelectron impact dissociation of N₂ is the main NO destroyer.  The net photoelectron impact excitation rate of N₂, which is responsible for the N₂(A) production, is larger than the ionization and dissociation rates and thus potentially very important.   Although the conservative assumptions regarding the level-specific NO yield from the N₂(A)+O reaction results in N₂(A) being a somewhat minor contributor, N₂(A) production is found to be the most efficient producer of NO among the thermospheric energy deposition processes. / Ph. D.

Accurate solar generation forecasting is critical for ensuring power system reliability, economics, and effectiveness and controlling the supply-demand balance. This research offers novel multi-branch spatio-temporal forecasting models to improve forecasting accuracy and minimize forecasting errors. The first step is to build temporal models employing advanced deep learning architectures, such as Long Short-Term Memory (LSTM), Gated Recurrent Unit (GRU), and GRU with Attention (AttGRU). Next, spatio-temporal solar forecasting models are constructed. A novel multi-branch Attentive Gated Recurrent Residual network (ResAttGRU) consisting of multiple branches of residual networks (ResNet), GRU, and the attention mechanism is introduced. The proposed multi-branch ResAttGRU is capable of modeling data at various resolutions, extracting hierarchical features, and capturing short- and long-term dependencies. Moreover, this network also presents a strong multi-time-scale representative, while GRUs can exploit temporal information at less computational cost than the popular LSTM. The novelty of the developed architecture is in the utilization of multiple convolutional-based branches to learn multi-time-scale features jointly, accelerate the learning process, and reduce overfitting. This dissertation also compares the multi-branch ResAttGRU networks with state-of-the-art deep learning methods using 18 years of NSRDB data at 12 solar sites. The proposed multi-branch ResAttGRU requires 7.1% fewer parameters than multi-branch residual LSTM (ResLSTM) while achieving similar average RMSE, MAE, and R-squared values. Finally, to effectively model spatial correlation among neighboring solar sites as well as to alleviate performance degradation due to overfitting of conventional neural networks, a spatio-temporal framework comprised of concatenated multi-branch Residual network and Transformer (ResTrans) is developed. Numerical results indicate that the multi-branch ResTrans structure achieves the highest forecasting accuracy, with an average RMSE of 0.049 ( W/m^2 ), an average MAE of 0.031 (W/m^2 ), and a R^2 coefficient of 97%. / Electrical and Computer Engineering

No description available.

Before vehicles were heavily relied on coal, fossil fuels and wind for power.  Now, they are rapidly being replaced by electric vehicles and or plug-in hybrid electric cars. But these electric cars are still faced with the problem of energy availability because they rely on energy from biomass, hydro power and wind turbines for power generation. The abundance of solar radiation and its use as solar energy as a power source in driving these rapidly increasing electric cars is not only an important decision but also a necessary condition for eradication of environmental pollution. This study presents a model for charging electric cars from solar energy. Little focus on detailed technologies involved from solar energy capture to battery charging but our main focus is how to provide a modified charging parking lot in Karlskrona city-Sweden. With a surface area of 2850m2, we were able to choose 1STH-350-WH as the right PV modules. Based on the latitude of our design area, a computed 71 degrees angle positioning between solar panel and roof so as to maximise the surface area and optimise the solar irradiance gathering. Based on the power output of approximately116kW these PV modules generated, we further analysed and selected SDP 30KW inverter and Monocrystalline Silicon (1SolTech 1STH-350-WH (350W) solar modules. Also we provide different car charging method by choosing the SAE J1772 standard as one of specifications for dedicated vehicle charging and Clipper Creek HSC-40 as our option of charger. With the data of the generating solar energy every day, charging time, consuming power, we can estimate how many cars the system can handle to charge. Moreover, our system provides AC power from AC power network by general socket type F. We finally concluded that, our model for charging of electric car batteries was not only supportive but efficient in terms of extracting solar energy from sunlight to charge electric cars, thus making the region an eco-friendly place.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-02-16T15:44:53Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese Ricardo Cesar de Andrade para Biblioteca Central.pdf: 5398475 bytes, checksum: 9946e56835bd8c5b975cbba26079b709 (MD5) / Made available in DSpace on 2017-02-16T15:44:53Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese Ricardo Cesar de Andrade para Biblioteca Central.pdf: 5398475 bytes, checksum: 9946e56835bd8c5b975cbba26079b709 (MD5) Previous issue date: 2016-07-20 / A radiação extraterrestre é atenuada pela atmosfera em diferentes proporções, dependendo, principalmente do ângulo zenital solar e da altitude no ponto de medição. Neste trabalho, são apresentados valores da radiação solar total acima da condição de céu claro, que, em alguns dias, superou a constante solar corrigida pela distância Sol-Terra (CSC). Assim, esta pesquisa relata uma análise detalhada do efeito lente produzido por nuvens na irradiação solar global medido no Nordeste do Brasil, nas cidades de Água Branca, Santana do Ipanema, Palmeira dos Índios, Laje, Pão de Açúcar, Arapiraca, Coruripe e Maceió, no período de janeiro a dezembro de 2008, e, para a cidade de Recife, nos meses de outubro e novembro de 2015. Foram feitas medições com 1 minuto de intervalo, usando o piranômetro B&W da Eppley com incerteza estimada de 5%. Verificou-se que: a) o fenômeno não é incomum; b) a duração do efeito pode atingir 34 minutos; c) a existência de um efeito sazonal, com maior probabilidade de ocorrência nos meses de abril e outubro; d) valores medidos da radiação solar superiores à radiação solar extraterrestre na ordem de 300 W/m2; e e) uma forte assimetria foi detectada no perfil de ocorrência do fenômeno entre o período da manhã e à tarde. Os dados aferidos demonstraram que a radiação extrema, acima do valor extraterrestre, com duração de até 30 minutos, pode significar índices UV (IUV) muito elevados e potencialmente perigosos. / The extraterrestrial radiation is attenuated by the earth atmosphere in different proportions depending mainly on the solar zenith angle and the altitude of the measurement point. This work presents the total solar radiation values above clear-sky conditions that in some days surpassed the Solar constant corrected by the Sun-Earth distance (CSC). Thus, this research reports a detailed analysis of lens effect produced by clouds in the global solar radiation measured in the Northeast of Brazil. Therefore in the cities of Água Branca, Santana de Ipanema, Palmeiras dos Índios, Laje, Pão de Açúcar, Arapiraca, Coruripe and Maceió, was measured between January and December of 2008, and in Recife from October and November of 2015. Measurements have been taken with one-minute intervals using Eppley and B&W pyrometers with an uncertainty estimated of 5%. It has been found that a) the phenomenon is not unusual; b) the duration of the effect can reach 34 minutes; c) the existence of a seasonal effect with greater probality of occurrence in April and October; d) the measurement values of extraterrestrial solar radiation in the order of 300 W/m² above normal condition; and e) a strong asymmetry was detected in the occurrence phenomenon profile between the span of the morning and in the afternoon. Accessed data indicates that the extreme solar radiation, above the extraterrestrial solar radiation, lasting up to 30 minutes, might indicates a very high and potentially dangerous UV index.