Solar Tracker and Wind Guide Designs to Improve the Energy Conversion in a Hybrid Energy Harvester System

This study focused on improving the energy conversion of hybrid solar panels and a wind turbine system. The improvement was produced by enhancing the system with a solar tracker and a wind guide. A microcontroller operated the single-axis solar tracker based on a solar elevation database at -6.91N, 107.61E. The wind guide was an Omni Directional Guide Vane (ODGV), designed to support the drag-type Savonius turbine. The ODGV’s inside and outside diameters were 540 mm and 1000 mm, respectively. The wind guide had a 30° polar angle between fins and produced a torque of 0.128 Nm at a wind speed of 4 m/s. The solar tracker increased the system performance by 47% and the wind guide by 166%.

Effectively Extracting Iceberg Freeboard Using Bi-Temporal Landsat-8 Panchromatic Image Shadows

The freshwater flux from icebergs into the Southern Ocean plays an important role in the global climate through its impact on the deep-water formation. Large uncertainties exist in the ice volume transported by Southern Ocean icebergs due to the sparse spatial and temporal coverage of observations, especially observations of ice thickness. The iceberg freeboard is a critical geometric parameter for measuring the thickness of an iceberg and then estimating its volume. This study developed a new, highly efficient shadow-height method to precisely measure the freeboard of various icebergs surrounded by sea ice using Landsat-8 Operational Land Imager 15-m bi-temporal panchromatic image shadows at low-solar-elevation angles. We evaluated and validated shadow length precision according to bi-temporal measurements and comparison with the measurements from the unmanned aerial vehicle. We determined freeboard precision according to shadow length precision and solar elevation angle. In our case study area, 4832 available freeboard measuring points with shadow length precision better than 2 pixels covered 376 icebergs with sizes ranging from 0.002 to 0.7 km² and with freeboard ranging from 2.3 to 83.4 m. At the solar elevation angles of 5.2°, the freeboard precision of 64.1% data could reach 1 m and 86.9% could reach 2 m. Our proposed method effectively filled in the data gap of existing freeboard measurement methods.

Temperature stratification and photosynthetically active radiation distribution in the Zostera noltii Hornemann canopy under shallow water conditions at different solar elevation angles (the Black sea)

Морские травы экологически важны, но чрезвычайно уязвимы перед антропогенными изменениями в прибрежных зонах, которые влияют на доступность света в этих экосистемах. При разной высоте Солнца над горизонтом в зондирующем режиме проводилось одновременное измерение значений температуры воды и интенсивности фотосинтетически активной радиации (IPAR) по профилю полога Zostera noltii Hornemann (высота полога 32 см.) в мелководной части Казачьей бухты (г. Севастополь, Черное море, 44°57′26″ с.ш., 33°40′33″ в.д.). Для полога Z. noltii характерен одномодальный тип вертикального распределения биомассы с максимумом (65,7 г (сухой массы) / м2) в его нижней части. Рассматривается изменение температурной стратификации и распределения IPAR по профилю растительного полога Z. noltii в течение светового дня. Seagrass is environmentally significant but extremely vulnerable in coastal areas to anthropogenic changes, which affect light availability. Simultaneous measurements of water temperature and photosynthetically active radiation (PAR) intensity in the sounding mode were taken at different solar elevation angles for the Zostera noltii Hornemann canopy (canopy height 32 cm) in shallow waters of the Cossack Bay (Sevastopol, the Black Sea, 44°57′26″ с.ш., 33°40′33″ в.д.). Z. noltii canopy is characterized by a unimodal type of biomass vertical distribution with its maximum (65,7 g (dry matter)/m2) in the lower part. Temperature stratification and IPAR distribution changes within the Z. noltii vegetation canopy profile during daylight hours are considered.

The Impacts of Fluorine-Doped Tin Oxide Photonic Crystals on a Cadmium Sulfide-Based Photoelectrode for Improved Solar Energy Conversion under Lower Incidence

Incident angle variation of light from the sun is a critical factor for the practical utilizations of solar energy devices. These devices typically receive the zenith of photon density under a solar elevation angle of 90°, and dramatic deletion of light density along with the decrease of solar elevation angle. Photonic crystals (PCs) with long range ordered arrays possess the controllable position of the photonic stop band (PSB) reliant on several factors, including incident angles, based on the Bragg–Snell law. The multiple scattering, refraction and inhibition of charge carrier recombination within the PSB suggests the potential capability for improving the efficiency of photoactive materials. In this work, we focus on the multiple scattering and refraction effects of PCs. A photoelectrode based on photonic crystal fluorine-doped tin oxide (PC FTO) film was fabricated, which allows the embedded photoactive materials (CdS nanoparticles) to benefit from the features of PCs under variable incidence, especially under lower incidence. The photoelectrode thus has enhanced overall photoelectrochemical (PEC) efficiency in different seasons, even if the increased surface area factor is deducted.

Solar Blue Light Radiation Enhancement during Mid to Low Solar Elevation Periods under Cloud Affected Skies

Solar blue-violet wavelengths (380−455 nm) are at the high energy end of the visible spectrum; referred to as “high energy visible” (HEV). Both chronic and acute exposure to these wavelengths has been often highlighted as a cause for concern with respect to ocular health. The sun is the source of HEV which reaches the Earth’s surface either directly or after scattering by the atmosphere and clouds. This research has investigated the effect of clouds on HEV for low solar elevation (solar zenith angles between 60° and 80°), simulating time periods when the opportunity for ocular exposure in global populations with office jobs is high during the early morning and late afternoon. The enhancement of “bluing” of the sky due to the influence of clouds was found to increase significantly with the amount of cloud. A method is presented for calculating HEV irradiance at sub-tropical latitudes from the more commonly measured global solar radiation (300–3000 nm) for all cases when clouds do and do not obscure the sun. The method; when applied to global solar radiation data correlates well with measured HEV within the solar zenith angle range 60° and 80° (R2 = 0.82; mean bias error (MBE) = −1.62%, mean absolute bias error (MABE) = 10.3% and root mean square error (RMSE) = 14.6%). The technique can be used to develop repeatable HEV hazard evaluations for human ocular health applications

Hypertemporal Imaging Capability of UAS Improves Photogrammetric Tree Canopy Models

Small uncrewed aerial systems (UASs) generate imagery that can provide detailed information regarding condition and change if the products are reproducible through time. Densified point clouds form the basic information for digital surface models and orthorectified mosaics, so variable dense point reconstruction will introduce uncertainty. Eucalyptus trees typically have sparse and discontinuous canopies with pendulous leaves that present a difficult target for photogrammetry software. We examine how spectral band, season, solar azimuth, elevation, and some processing settings impact completeness and reproducibility of dense point clouds for shrub swamp and Eucalyptus forest canopy. At the study site near solar noon, selecting near infrared camera increased projected tree canopy fourfold, and dense point features more than 2 m above ground were increased sixfold compared to red spectral bands. Near infrared (NIR) imagery improved projected and total dense features two- and threefold, respectively, compared to default green band imagery. The lowest solar elevation captured (25°) consistently improved canopy feature reconstruction in all spectral bands. Although low solar elevations are typically avoided for radiometric reasons, we demonstrate that these conditions improve the detection and reconstruction of complex tree canopy features in natural Eucalyptus forests. Combining imagery sets captured at different solar elevations improved the reproducibility of dense point clouds between seasons. Total dense point cloud features reconstructed were increased by almost 10 million points (20%) when imagery used was NIR combining solar noon and low solar elevation imagery. It is possible to use agricultural multispectral camera rigs to reconstruct Eucalyptus tree canopy and shrub swamp by combining imagery and selecting appropriate spectral bands for processing.

Extracting icebergs freeboard from the shadows in Landsat-8 panchromatic images

<p><strong>Abstract:</strong> The iceberg freeboard is an important geometric parameter for measuring the thickness of the iceberg and then estimating its volume. Based on the fact that the iceberg can cast elongated shadow on the surface of sea ice in winter, this paper proposes a method to measure the iceberg freeboard using shadow length and the predefined or estimated solar elevation angle. Three Landsat-8 panchromatic images are selected to test our method, with center solar elevation angle of respectively 5.43°, 7.49°and 11.01° on August 29, September 7, and 16 September in 2016. Shadow lengths of five isolated tabular icebergs are automatically extracted to calculate the freeboard height. For the accuracy assessment, we use the matching points at the different time as cross validation. The results show that the measurement error of shadow length is less than one pixel. When the sun elevation angle is lower than 11.01°, the Root Mean Square Error (RMSE) of the iceberg freeboard from the panchromatic 15 m image is less than 2.0 m, and the Mean Absolute Error (MAE) is less than 1.5 m. Such experiment shows that: under the angle of low solar elevation in winter, the landsat-8 panchromatic 15 m image can be used for high-precision measurement of the iceberg freeboard, and has the potential to measure the Antarctic iceberg freeboard in large scale.</p><p><strong>Key </strong><strong>words:</strong> Antarctic, icebergs, freeboard, shadow altimetry, Landsat-8</p><p> </p>