- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Retrieval of Chlorophyll a from Sentinel-2 MSI Data for the European Union Water Framework Directive Reporting Purposes
摘要： The European Parliament and The Council of the European Union have established the Water Framework Directive (2000/60/EC) for all European Union member states to achieve, at least, 'good' ecological status of all water bodies larger than 50 hectares in Europe. The MultiSpectral Instrument onboard European Space Agency satellite Sentinel-2 has suitable 10, 20, 60 m spatial resolution to monitor most of the Estonian lakes as required by the Water Framework Directive. The study aims to analyze the suitability of Sentinel-2 MultiSpectral Instrument data to monitor water quality in inland waters. This consists of testing various atmospheric correction processors to remove the influence of atmosphere and comparing and developing chlorophyll a algorithms to estimate the ecological status of water in Estonian lakes. This study shows that the Sentinel-2 MultiSpectral Instrument is suitable for estimating chlorophyll a in water bodies and tracking the spatial and temporal dynamics in the lakes. However, atmospheric corrections are sensitive to surrounding land and often fail in narrow and small lakes. Due to that, deriving satellite-based chlorophyll a is not possible in every case, but initial results show the Sentinel-2 MultiSpectral Instrument could still provide complementary information to in situ data to support Water Framework Directive monitoring requirements.
关键词： atmospheric correction,chlorophyll a,optically complex waters,remote sensing,European Union Water Framework Directive (2000/60/EC),ecological status of water bodies,Copernicus,Sentinel-2 MultiSpectral Instrument
更新于2025-09-23 15:22:29
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Field Water Balance Closure with Actively Heated Fiber-Optics and Point-Based Soil Water Sensors
摘要： While traditional soil water sensors measure soil water content (SWC) at point scale, the actively heated fiber-optics (AHFO) sensor measures the SWC at field scale. This study compared the performance of a distributed (e.g., AHFO) and a point-based sensor on closing the field water balance and estimating the evapotranspiration (ET). Both sensors failed to close the water balance and produced larger errors in estimated ET (ETε), particularly for longer time periods with >60 mm change in soil water storage (?SWS), and this was attributed to a lack of SWC measurements from deeper layers (>0.24 m). Performance of the two sensors was different when only the periods of <60 mm ?SWS were considered; significantly lower residual of the water balance (Re) and ETε of the distributed sensor showed that it could capture the small-scale spatial variability of SWC that the point-based sensor missed during wet (70–104 mm SWS) periods of <60 mm ?SWS. Overall, this study showed the potential of the distributed sensor to provide a more accurate value of SWS at field scale and to reduce the errors in water balance for shorter wet periods. It is suggested to include SWC measurements from deeper layers to better evaluate the performance of the distributed sensor, especially for longer time periods of >60 mm ?SWS, in future studies.
关键词： soil water storage,actively heated fiber-optics,soil water balance
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Budapest (2018.7.1-2018.7.5)] 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Method for Calculating Electronic Polarizability of Water Molecules and Refractive Index
摘要： A method for calculating the electronic polarizability of water molecules is proposed. In the approximation of this method, the electronic components of the hyperpolarizability of the first and second order for the water molecule are determined.
关键词： water molecule,electron polarizability,refractive index,hyperpolarizability,electronic polarizability,molar refraction
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference on Advanced Science and Engineering (ICOASE) - Duhok (2018.10.9-2018.10.11)] 2018 International Conference on Advanced Science and Engineering (ICOASE) - Manufacturing Procedure of a Hybrid Design of Solar Collector (Sterilization and Water Heating) By Solar and Electrical Energy
摘要： The purpose of the research is to design a hybrid solar collector, called (L1). This Collector operates by solar energy during daylight hours, which is approximately (12) hours, the work of the solar collector (L1) continues during night by using electrical power. Solar collector was tested during the period of December - 2017 to May – 2018.The results were excellent where it’s records high temperature during the period from March - May 2018. Temperature recorded more than 100 Co. The outlet water from the solar collector (L1) was sterilized due to the high heating degree of the water, it reached boiling degree. The design of (L1) is suitable for a lot of environment or weather conditions, because it depends on the collection of the solar radiation in a small surface area; in addition, it works in low electrical power. Tests for (L1) were conducted in Basra city, southern Iraq, on latitude 30.5oN and longitude 47.8oE. Manufacturing of this solar collector is very easy with low cost. It can be used it in houses, scientific and health institutions.
关键词： Hybrid,solar collector,sterilization,Water heating,Renewable energy,Solar energy
更新于2025-09-23 15:22:29
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Automatic and Unsupervised Water Body Extraction Based on Spectral-Spatial Features Using GF-1 Satellite Imagery
摘要： Water body extraction from remote sensing imagery is an essential and nontrivial issue due to the complexity of the spectral characteristics of various kinds of water bodies and the redundant background information. An automatic multifeature water body extraction (MFWE) method integrating spectral and spatial features is proposed in this letter for water body extraction from GF-1 multispectral imagery in an unsupervised way. This letter first discusses a spatial feature index, called the pixel region index (PRI), to describe the smoothness in a local area surrounding a pixel. PRI is advantageous for assisting the normalized difference water index (NDWI) in detecting major water bodies, especially in urban areas. On the other hand, part of the water pixels near the borders may not be included in major water bodies, k-means clustering is subsequently conducted to cluster all the water pixels into the same group as a guide map. Finally, the major water bodies and the guide map are merged to obtain the final water mask. Our experimental results demonstrate that accurate water masks were achieved for all seven GF-1 imagery scenes examined. Three images with a complex background and water conditions were used to quantitatively compare the proposed method to NDWI thresholding and support vector machine classification, which verified the higher accuracy and effectiveness of the proposed method.
关键词： water body extraction,image classification,spectral-spatial feature,GF-1 imagery
更新于2025-09-23 15:22:29
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[IEEE 2018 53rd International Universities Power Engineering Conference (UPEC) - Glasgow, United Kingdom (2018.9.4-2018.9.7)] 2018 53rd International Universities Power Engineering Conference (UPEC) - Design of a PV-powered DC water pump system for irrigation: a case study
摘要： A PV-powered automatic irrigation system is designed and implemented in this paper. Dominant factors of the system such as the effect of solar radiation on motor power, current, and water discharge are considered in this study. The proposed system is implemented in the field to irrigate corn plant (maize) considering the optimum tilt angle for Duhok city. A new method for measuring the moisture content in the soil and sufficient level of moisture needed for normal growth of the crop is presented to design a timer for the system to reduce the amount of wasted water. Moisture sensors are used to check the availability of water in the soil and to enable the microcontroller to control the operation status of the pump. The results show that the proposed irrigation method is more accurate and efficient than the conventional irrigation methods in terms of the amount of the water used for irrigation, and the accuracy of irrigating times based on changing local climate. The results clearly demonstrate that the proposed system is more cost effective way of irrigation and more environmental friendly in terms of the amount of water used in an area known for water scarcity.
关键词： water Pumps,DC motor,irrigation,tilt angle,PV cell
更新于2025-09-23 15:22:29
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A Wideband Polarization-Reconfigurable Water Dielectric Resonator Antenna
摘要： A water dielectric resonator antenna (DRA) with reconfiguration and broadband characteristics is presented. By injecting pure water into various cavities of the plexiglass holder, the antenna can be switched among left hand circular polarization (LHCP), right hand circular polarization (RHCP) and linear polarization (LP) in almost the same operating frequency range. With the high relative permittivity, water acts as a dielectric resonator as well as an interface similar to electric wall to form a broad axial ratio bandwidth. Thus a broad usable bandwidth is measured to be over 22%, and the measured radiation efficiency and realized gain centralize in 60%-70% and 3-4 dBi respectively.
关键词： dielectric resonator antenna,water antenna,broad bandwidth,dielectric dense patch antenna,reconfigurability
更新于2025-09-23 15:22:29
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Water Body Extraction From Very High-Resolution Remote Sensing Imagery Using Deep U-Net and a Superpixel-Based Conditional Random Field Model
摘要： Water body extraction (WBE) has attracted considerable attention in the field of remote sensing image analysis. Herein, we present an enhanced deep convolutional encoder–decoder (DCED) network (or Deep U-Net) specifically tailored to WBE from remote sensing images by applying superpixel segmentation and conditional random fields (CRFs). First, we preclassify the entire remote sensing image into the water and nonwater areas via Deep U-Net, using the results of class membership probabilities as the unary potential in the CRF model. The pairwise potential of CRF is defined by a linear combination of Gaussian kernels, which forms a fully connected neighbor structure. Next, regional restriction is incorporated into the approach to enhance the consistency of the connected area. We use the simple linear iterative clustering algorithm to generate superpixels and correct the binary classification results by calculating their average posterior probabilities. Finally, a highly efficient approximate inference algorithm, mean-field inference, is generated for the final model. The results from the experimental application to GaoFen-2 images and WorldView-2 images demonstrate that the proposed approach exhibits competitive quantitative and qualitative performance, which effectively reduces salt-and-pepper noise and retains the edge structures of water bodies. Compared to existing state-of-the-art methods, our proposed method achieves superior final results.
关键词： Conditional random fields (CRFs),Deep U-Net,superpixel,regional restriction (RR),water body extraction (WBE)
更新于2025-09-23 15:22:29
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Scaling up electrodes for photoelectrochemical water splitting: fabrication process and performance of 40 cm2 LaTiO2N photoanodes
摘要： A scalable process for particle-based photoanodes is developed. The electrodes are versatilely made of photocatalytically active semiconductor particles, here LaTiO2N, and optionally coated with co-catalysts and protecting components, all immobilized on a conducting substrate. The involved fabrication steps are restricted to scalable processes like electrophoretic deposition, annealing in air and dip coating. Special care is taken to ensure charge transport in between particles and to the substrate by adding conducting connectors. Adapting the fabrication steps, the geometrical electrode dimension is increased from the size of a typical lab electrode of 1 cm2 to 40 cm2. The quality of the scale up process is characterized by comparing the photoanodes in terms of thickness, light absorption properties and morphology. For several compositions, the electrochemical performance of both electrode sizes is assessed by measuring photocurrents and Faraday efficiencies. The comparison revealed a complex upscaling behavior and showed that photoelectrode size affected performance already on the 0.1 m scale.
关键词： photoelectrodes,energy conversion,LaTiO2N,electrode size,water splitting
更新于2025-09-23 15:22:29
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[IEEE 2018 4th International Conference on Renewable Energies for Developing Countries (REDEC) - Beirut, Lebanon (2018.11.1-2018.11.2)] 2018 4th International Conference on Renewable Energies for Developing Countries (REDEC) - Phase Change Materials in a Domestic Solar Hot Water Storage Tank of the Lebanese Market
摘要： The availability of some kinds of renewable energy resources is un-continuous, for example the solar collectors can only produce heat when the sun is shining. Thermal Energy Storage (TES) is crucial to match between the intermittent solar heat supply and the heat demand. In this paper, a Phase Change Material (PCM) is integrated in the Domestic Solar Hot Water Storage Tank (DSHWST) as a Latent Heat Storage (LHT). Based on the application requirements in Lebanon, a suitable PCM is selected. While this PCM solidifies, it releases its heat and keeps the water inside the DSHWST warmer than 55 oC along 10 hours. The needed mass of PCM was calculated and two types of containers were investigated: the tubes and the spheres. As well as, the comparison between DSHWST integrated with PCM (DSHWST-PCM) and the Conventional Domestic Solar Hot Water Storage Tank (CDSHWST) is introduced, in order to examine the performance of PCM heating against that with an Electrical Resistance (ER). Features are expressed in terms of system payback and CO2 emission. Due to the issue of electrical power availability in Lebanon, the PCM integrated in The DSHWST has the following two advantages: yearly, reducing the primary electricity power by about 6.5 MWh and get rid of about 5.5 tons of CO2.
关键词： Thermal Energy Storage,Phase Change Material,Hot Water Storage Tank,Lebanon
更新于2025-09-23 15:22:29