- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Cloud shadow speed sensor
摘要： Changing cloud cover is a major source of solar radiation variability and poses challenges for the integration of solar energy. A compact and economical system is presented that measures cloud shadow motion vectors to estimate power plant ramp rates and provide short-term solar irradiance forecasts. The cloud shadow speed sensor (CSS) is constructed using an array of luminance sensors and a high-speed data acquisition system to resolve the progression of cloud passages across the sensor footprint. An embedded microcontroller acquires the sensor data and uses a cross-correlation algorithm to determine cloud shadow motion vectors. The CSS was validated against an artificial shading test apparatus, an alternative method of cloud motion detection from ground-measured irradiance (linear cloud edge, LCE), and a UC San Diego sky imager (USI). The CSS detected artificial shadow directions and speeds to within 15? and 6 % accuracy, respectively. The CSS detected (real) cloud shadow directions and speeds with average weighted root-mean-square difference of 22? and 1.9 m s?1 when compared to USI and 33? and 1.5 m s?1 when compared to LCE results.
关键词： cloud motion vectors,solar irradiance,cloud shadow speed sensor,forecasting,solar energy
更新于2025-09-09 09:28:46
-
[ACM Press the 1st International Workshop - New Delhi, India (2018.10.29-2018.10.29)] Proceedings of the 1st International Workshop on Communication and Computing in Connected Vehicles and Platooning - C3VP '18 - On Feasibility of VLC Based Car-to-Car Communication Under Solar Irradiance and Fog Conditions
摘要： This paper investigates the impact of solar irradiance and fog condition on visible light communication (VLC) based car-to car (C2C) communication for two capital cities, New Delhi and London. The bit error rate (BER) variation over a day has been compared for both the cities for the month of March, June and December. It has been shown that for a given BER threshold performance, the impact of solar irradiance is more pronounced in month of June especially at New Delhi when solar irradiance reaches its peak. It has also been shown that in month of December, fog is one of the most significant climatic factors that greatly influences the VLC based C2C communication in terms of atmospheric attenuation. This paper also establishes the relationship for the minimum safety distance required between cars based on two-second rule, car speed and angle between cars. The minimum safety distance which would be required to avoid any rear-end collision especially during light or dense fog in the month of December has also been compared for New Delhi and London.
关键词： safety distance,fog conditions,solar irradiance,car-to-car communication,visible light communication,bit error rate
更新于2025-09-09 09:28:46
-
Autonomous marine hyperspectral radiometers for determining solar irradiances and aerosol optical properties
摘要： We have developed two hyperspectral radiometer systems which require no moving parts, shade rings or motorised tracking, making them ideally suited for autonomous use in the inhospitable remote marine environment. Both systems are able to measure direct and diffuse hyperspectral irradiance in the wavelength range 350–1050 nm at 6 nm (Spectrometer 1) or 3.5 nm (Spectrometer 2) resolution. Marine field trials along a 100? transect (between 50? N and 50? S) of the Atlantic Ocean resulted in close agreement with existing commercially available instruments in measuring (1) photosynthetically available radiation (PAR), with both spectrometers giving regression slopes close to unity (Spectrometer 1: 0.960; Spectrometer 2: 1.006) and R2 ～ 0.96; (2) irradiant energy, with R2～ 0.98 and a regression slope of 0.75 which can be accounted for by the difference in wavelength integration range; and (3) hyperspectral irradiance where the agreement on average was between 2 and 5 %. Two long duration land-based field campaigns of up to 18 months allowed both spectrometers to be well calibrated. This was also invaluable for empirically correcting for the wider field of view (FOV) of the spectrometers in comparison with the current generation of sun photometers (～ 7.5? compared with ～ 1?). The need for this correction was also confirmed and independently quantified by atmospheric radiative transfer modelling and found to be a function of aerosol optical depth (AOD) and solar zenith angle. Once Spectrometer 2 was well calibrated and the FOV effect corrected for, the RMSE in retrievals of AOD when compared with a CIMEL sun photometer were reduced to ～ 0.02–0.03 with R2 > 0.95 at wavelengths 440, 500, 670 and 870 nm. Corrections for the FOV as well as ship motion were applied to the data from the marine field trials. This resulted in AOD500 nm ranging between 0.05 in the clear background marine aerosol regions and ～ 0.5 within the Saharan dust plume. The RMSE between the handheld Microtops sun photometer and Spectrometer 2 was between 0.047 and 0.057 with R2 > 0.94.
关键词： hyperspectral radiometer,autonomous measurement,marine environment,solar irradiance,aerosol optical depth
更新于2025-09-04 15:30:14