scholarly journals The new sun-sky-lunar Cimel CE318-T multiband photometer – a comprehensive performance evaluation

2015 ◽  
Vol 8 (10) ◽  
pp. 11077-11138
Author(s):  
A. Barreto ◽  
E. Cuevas ◽  
M. J. Granados-Muñoz ◽  
L. Alados-Arboledas ◽  
P. M. Romero ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Water Vapor ◽  
Near Infrared ◽  
Quantitative Estimation ◽  
Tracking System ◽  
Visible Spectral Range ◽  
The Sun ◽  
Subsequent Performance ◽  
New Device ◽  
Filter Radiometer

Abstract. This paper presents the new photometer CE318-T, able to perform daytime and nighttime photometric measurements using the sun and the moon as light source. Therefore, this new device permits to extract a complete cycle of diurnal aerosol and water vapor measurements valuable to enhance atmospheric monitoring. In this study we have found significantly higher triplets precision when comparing the CE318-T master and the Cimel AErosol RObotic NETwork (AERONET) master (CE318-AERONET) triplets as a result of the new CE318-T tracking system. Regarding the instrument calibration, a new methodology to transfer the calibration from a master (Sun Ratio technique) is presented and discussed. It allows us to reduce the previous complexities inherent to nocturnal calibration. A quantitative estimation of CE318-T AOD uncertainty by means of error propagation theory during daytime revealed AOD uncertainties (uDAOD) for Langley-calibrated instruments similar to the expected values for other reference instruments (0.002–0.009). We have also found uDAOD values similar to the values reported in sun photometry for field instruments (~ 0.015). In the case of nighttime period, the CE318-T estimated uncertainty (uNAOD) is dependent not only on the calibration technique but also on illumination conditions and the instrumental noise. These values range from 0.011–0.019 for Lunar Langley calibrated instruments to 0.012–0.021 for instruments calibrated using the Sun Ratio technique. A subsequent performance evaluation including CE318-T and collocated measurements from independent reference instruments has served to assess the CE318-T performance as well as to confirm its estimated uncertainty. Daytime AOD evaluation performed at Izaña station from March to June 2014, encompassed measurements from a reference CE318-T, a CE318-AERONET master, a Precision Filter Radiometer (PFR) and a Precision SpectroRadiometer (PSR) prototype, reporting low AOD discrepancies between the four instruments (up to 0.006). The nocturnal AOD evaluation was performed using CE318-T and star photometer collocated measurements and also by means of a day/night coherence transition test using the master CE318-T and the CE318 daytime data from the CE318-AERONET master. Results showed low discrepancies with star photometer at 870 and 500 nm channels (≤ 0.013) and differences with AERONET daytime data (1 h after and before sunset and sunrise) in agreement with the estimated uNAOD values at all illumination conditions in case of channels within the visible spectral range, and only for high moon's illumination conditions in case of near infrared channels. Precipitable water vapor (PWV) validation showed a good agreement between CE318-T and Global Navigation Satellite System (GNSS) PWV values for all illumination conditions, within the expected precision for sun photometry. Finally, two case studies have been included to highlight the ability of the new CE318-T to capture the diurnal cycle of aerosols and water vapor as well as short-term atmospheric variations, critical for climate studies.

scholarly journals The new sun-sky-lunar Cimel CE318-T multiband photometer – a comprehensive performance evaluation

2016 ◽  
Vol 9 (2) ◽  
pp. 631-654 ◽  
Author(s):  
África Barreto ◽  
Emilio Cuevas ◽  
María-José Granados-Muñoz ◽  
Lucas Alados-Arboledas ◽  
Pedro M. Romero ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Water Vapour ◽  
Quantitative Estimation ◽  
Tracking System ◽  
Gain Factor ◽  
The Sun ◽  
Night Time ◽  
Subsequent Performance ◽  
New Device ◽  
Filter Radiometer

Abstract. This paper presents the new photometer CE318-T, able to perform daytime and night-time photometric measurements using the sun and the moon as light source. Therefore, this new device permits a complete cycle of diurnal aerosol and water vapour measurements valuable to enhance atmospheric monitoring to be extracted. In this study we have found significantly higher precision of triplets when comparing the CE318-T master instrument and the Cimel AErosol RObotic NETwork (AERONET) master (CE318-AERONET) triplets as a result of the new CE318-T tracking system. Regarding the instrument calibration, two new methodologies to transfer the calibration from a reference instrument using only daytime measurements (Sun Ratio and Sun-Moon gain factor techniques) are presented and discussed. These methods allow the reduction of the previous complexities inherent to nocturnal calibration. A quantitative estimation of CE318-T AOD uncertainty by means of error propagation theory during daytime revealed AOD uncertainties (uDAOD) for Langley-calibrated instruments similar to the expected values for other reference instruments (0.002–0.009). We have also found uDAOD values similar to the values reported in sun photometry for field instruments ( ∼  0.015). In the case of the night-time period, the CE318-T-estimated standard combined uncertainty (uNAOD) is dependent not only on the calibration technique but also on illumination conditions and the instrumental noise. These values range from 0.011–0.018 for Lunar Langley-calibrated instruments to 0.012–0.021 for instruments calibrated using the Sun Ratio technique. In the case of moon-calibrated instruments using the Sun-Moon gain factor method and sun-calibrated using the Langley technique, we found uNAOD ranging from 0.016 to 0.017 (up to 0.019 in 440 nm channel), not dependent on any lunar irradiance model.A subsequent performance evaluation including CE318-T and collocated measurements from independent reference instruments has served to assess the CE318-T performance as well as to confirm its estimated uncertainty. Daytime AOD evaluation, performed at Izaña station from March to June 2014, encompassed measurements from a reference CE318-T, a CE318-AERONET master instrument, a Precision Filter Radiometer (PFR) and a Precision Spectroradiometer (PSR) prototype, reporting low AOD discrepancies between the four instruments (up to 0.006). The nocturnal AOD evaluation was performed using CE318-T- and star-photometer-collocated measurements and also by means of a day/night coherence transition test using the CE318-T master instrument and the CE318 daytime data from the CE318-AERONET master instrument. Results showed low discrepancies with the star photometer at 870 and 500 nm channels ( ≤  0.013) and differences with AERONET daytime data (1 h after and before sunset and sunrise) in agreement with the estimated uNAOD values at all illumination conditions in the case of channels within the visible spectral range, and only for high moon's illumination conditions in the case of near-infrared channels.Precipitable water vapour (PWV) validation showed a good agreement between CE318-T and Global Navigation Satellite System (GNSS) PWV values for all illumination conditions, within the expected precision for sun photometry.Finally, two case studies have been included to highlight the ability of the new CE318-T to capture the diurnal cycle of aerosols and water vapour as well as short-term atmospheric variations, critical for climate studies.

scholarly journals Tracking eye-gaze in smart home systems (SHS): first insights from eye-tracking and self-report measures

2021 ◽  
Author(s):  
Federico Cassioli ◽  
Laura Angioletti ◽  
Michela Balconi
Keyword(s):  
Eye Tracking ◽  
Personality Traits ◽  
Smart Home ◽  
Near Infrared ◽  
Tracking System ◽  
Eye Gaze ◽  
Self Report ◽  
Visual Exploration ◽  
Living Room ◽  
Psychological Traits

AbstractHuman–computer interaction (HCI) is particularly interesting because full-immersive technology may be approached differently by users, depending on the complexity of the interaction, users’ personality traits, and their motivational systems inclination. Therefore, this study investigated the relationship between psychological factors and attention towards specific tech-interactions in a smart home system (SHS). The relation between personal psychological traits and eye-tracking metrics is investigated through self-report measures [locus of control (LoC), user experience (UX), behavioral inhibition system (BIS) and behavioral activation system (BAS)] and a wearable and wireless near-infrared illumination based eye-tracking system applied to an Italian sample (n = 19). Participants were asked to activate and interact with five different tech-interaction areas with different levels of complexity (entrance, kitchen, living room, bathroom, and bedroom) in a smart home system (SHS), while their eye-gaze behavior was recorded. Data showed significant differences between a simpler interaction (entrance) and a more complex one (living room), in terms of number of fixation. Moreover, slower time to first fixation in a multifaceted interaction (bathroom), compared to simpler ones (kitchen and living room) was found. Additionally, in two interaction conditions (living room and bathroom), negative correlations were found between external LoC and fixation count, and between BAS reward responsiveness scores and fixation duration. Findings led to the identification of a two-way process, where both the complexity of the tech-interaction and subjects’ personality traits are important impacting factors on the user’s visual exploration behavior. This research contributes to understand the user responsiveness adding first insights that may help to create more human-centered technology.

scholarly journals Spaceborne Estimation of Leaf Area Index in Cotton, Tomato, and Wheat Using Sentinel-2

Land ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 505
Author(s):  
Gregoriy Kaplan ◽  
Offer Rozenstein
Keyword(s):  
Water Vapor ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Vegetation Index ◽  
Near Infrared ◽  
Linear Regression Models ◽  
Area Index ◽  
Estimation Performance ◽  
Red Edge ◽  
Sentinel 2

Satellite remote sensing is a useful tool for estimating crop variables, particularly Leaf Area Index (LAI), which plays a pivotal role in monitoring crop development. The goal of this study was to identify the optimal Sentinel-2 bands for LAI estimation and to derive Vegetation Indices (VI) that are well correlated with LAI. Linear regression models between time series of Sentinel-2 imagery and field-measured LAI showed that Sentinel-2 Band-8A—Narrow Near InfraRed (NIR) is more accurate for LAI estimation than the traditionally used Band-8 (NIR). Band-5 (Red edge-1) showed the lowest performance out of all red edge bands in tomato and cotton. A novel finding was that Band 9 (Water vapor) showed a very high correlation with LAI. Bands 1, 2, 3, 4, 5, 11, and 12 were saturated at LAI ≈ 3 in cotton and tomato. Bands 6, 7, 8, 8A, and 9 were not saturated at high LAI values in cotton and tomato. The tomato, cotton, and wheat LAI estimation performance of ReNDVI (R2 = 0.79, 0.98, 0.83, respectively) and two new VIs (WEVI (Water vapor red Edge Vegetation Index) (R2 = 0.81, 0.96, 0.71, respectively) and WNEVI (Water vapor narrow NIR red Edge Vegetation index) (R2 = 0.79, 0.98, 0.79, respectively)) were higher than the LAI estimation performance of the commonly used NDVI (R2 = 0.66, 0.83, 0.05, respectively) and other common VIs tested in this study. Consequently, reNDVI, WEVI, and WNEVI can facilitate more accurate agricultural monitoring than traditional VIs.

Microcontroller Based Single Axis Intelligent Control Sun Tracker for Parabolic Trough Collectors

2012 ◽  
Vol 562-564 ◽  
pp. 1772-1775
Author(s):  
Shakeel Akram ◽  
Farhan Hameed Malik ◽  
Rui Jin Liao ◽  
Bin Liu ◽  
Tariq Nazir
Keyword(s):  
Energy Efficiency ◽  
Embedded System ◽  
Alternative Energy ◽  
Power Plants ◽  
Tracking System ◽  
Appropriate Technology ◽  
Working Fluid ◽  
The Sun ◽  
Solar Collectors ◽  
Parabolic Trough

Due to the complex design and high costs of production, solar thermal systems have fallen behind in the world of alternative energy systems. Different mechanisms are applied to increase the efficiency of the solar collectors and to reduce the cost. Solar tracking system is the most appropriate technology to increase the efficiency of solar collectors as well as solar power plants by tracking the sun timely. In order to maximize the efficiency of collectors, one needs to keep the reflecting surface of parabolic trough collectors perpendicular to the sun rays. For this purpose microcontroller based real time sun tracker is designed which is controlled by an intelligent algorithm using shadow technique. The aim of the research project is to test the solar-to-thermal energy efficiency by tracking parabolic trough collector (PTC). The energy efficiency is determined by measuring the temperature rise of working fluid as it flows through the receiver of the collector when it is properly focused. The design tracker is also simulated to check its accuracy. The main purpose to design this embedded system is to increase the efficiency and reliability of solar plants by reducing size, complexity and cost of product.

scholarly journals High Precision Optical Tracking System Based on near Infrared Trinocular Stereo Vision

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2528
Author(s):  
Songlin Bi ◽  
Yonggang Gu ◽  
Jiaqi Zou ◽  
Lianpo Wang ◽  
Chao Zhai ◽  
...  
Keyword(s):  
High Precision ◽  
Stereo Vision ◽  
Near Infrared ◽  
Nearest Neighbor ◽  
Tracking System ◽  
Optical Tracking ◽  
Tracking Accuracy ◽  
Optical Tracking System ◽  
Dynamic Tracking ◽  
Trinocular Stereo

A high precision optical tracking system (OTS) based on near infrared (NIR) trinocular stereo vision (TSV) is presented in this paper. Compared with the traditional OTS on the basis of binocular stereo vision (BSV), hardware and software are improved. In the hardware aspect, a NIR TSV platform is built, and a new active tool is designed. Imaging markers of the tool are uniform and complete with large measurement angle (>60°). In the software aspect, the deployment of extra camera brings high computational complexity. To reduce the computational burden, a fast nearest neighbor feature point extraction algorithm (FNNF) is proposed. The proposed method increases the speed of feature points extraction by hundreds of times over the traditional pixel-by-pixel searching method. The modified NIR multi-camera calibration method and 3D reconstruction algorithm further improve the tracking accuracy. Experimental results show that the calibration accuracy of the NIR camera can reach 0.02%, positioning accuracy of markers can reach 0.0240 mm, and dynamic tracking accuracy can reach 0.0938 mm. OTS can be adopted in high-precision dynamic tracking.

Design, Development and Performance Test of Two-Axis Solar Tracker System

2014 ◽  
Vol 704 ◽  
pp. 350-354
Author(s):  
Muhammad Ikram Mohd Rashid ◽  
Nik Fadhil bin Nik Mohammed ◽  
Suliana binti Ab Ghani ◽  
Noor Asiah Mohamad
Keyword(s):  
Tilt Angle ◽  
Solar Collector ◽  
Performance Test ◽  
Tracking System ◽  
Electrical Power ◽  
Solar Thermal ◽  
The Sun ◽  
Solar Pv ◽  
Design Development ◽  
Solar Tracking

The energy extracted from photovoltaic (PV) or solar thermal depends on solar insolation. For the extraction of maximum energy from the sun, the plane of the solar collector should always be normal to the incident radiation. Sun trackers move the solar collector to follow the sun trajectories and keep the orientation of the solar collector at an optimal tilt angle. Energy efficiency of solar PV or solar thermal can be substantially improved using solar tracking system. In this paper, an automatic solar tracking system has been designed and developed using DC motor on a mechanical structure with gear arrangement. The movements of two-axis solar trackers for the elevation and azimuth angles are programmed according to the mathematical calculation by using the Borland C++ Builder. Performance of the proposed system over the important parameter like solar radiation received on the collector, maximum hourly electrical power has been evaluated and compared with those for fixed tilt angle solar collector.

scholarly journals Intelligence Solar Power System with Mobile Power Analysis

2021 ◽  
pp. 95-101
Author(s):  
Balaji K ◽  
Dharshan T R ◽  
Mahendran P ◽  
Priyadharsini R
Keyword(s):  
Solar Cells ◽  
Power Output ◽  
Power Analysis ◽  
Tracking System ◽  
Maximum Amount ◽  
Solar Panel ◽  
The Sun ◽  
Energy Demands ◽  
Solar Tracking ◽  
Reducing Costs

The renewable energies, solar energy is the only energy gained its popularity and importance quickly. Through the solar tracking system, we can produce an abundant amount of energy which makes the solar panel’s workability much more efficient. Perpendicular proportionality of the solar panel with the sun rays is the reason lying behind its efficiency. Pecuniary, its installation charge is high provided cheaper options are also available. The main control circuit is based upon NodeMcu microcontroller. Programming of this device is done in the manner that the LDR sensor, in accordance with the detection of the sun rays, will provide direction to the DC Motor that in which way the solar panel is going to revolve. Through this, the solar panel is positioned in such a manner that the maximum amount of sun rays could be received. Though a hike in the efficiency of the solar panel had a handsome increase still perfection was a far-fetched goal for it. Below 40%, most of the panels still hover to operate. Consequently, peoples are compelled to purchase a number of panels in order to meet their energy demands or purchase single systems with large outputs. Availability of the solar cells types with higher efficiencies is on provided they are too costly to purchase. Ways to be accessed for increasing solar panel efficiencies are a plethora in number still one of the ways to be availed for accomplishing the said purpose while reducing costs, is tracking. Tracking helps in the wider projection of the panel to the Sun with increased power output. It could be dual or single axis tracker

scholarly journals Minimizing the Cosine Loss in a Solar Tower Power Plant by a Change in the Heliostat Position and Number

2020 ◽  
Vol 9 (3) ◽  
pp. 2302-2304
Keyword(s):  
Solar Radiation ◽  
Tracking System ◽  
Working Fluid ◽  
The Sun ◽  
Incident Solar Radiation ◽  
Concentrated Solar Energy ◽  
Central Receiver ◽  
Receiver System ◽  
Concentrated Solar Radiation ◽  
Solar Rays

Concentrating Solar Power (CSP) focuses sunlight in order to use the heat energy of the sun. In a central receiver system configuration, many mirrors (heliostats) individually track the sun and reflect the concentrated solar energy onto a receiver on top of a tower. The receiver contains the working fluid which is heated by the concentrated solar radiation. The useful energy that absorbed by the water flows through the receiver in solar tower plant depending on the angle between the solar rays and the position of heliostat in the region of work. Heliostat will reflect the incident solar radiation in the direction of the receiver founded in the top of the tower, in order to get a maximum incident solar radiation on the heliostat reflection area. Because of the cosine factor loss effect due to the sun position is variable along the day from sunrise to sunset, which must be in a minimum value, therefore an automated tracking system with dual axes as a control system with sensors had been built and used to stay the sunrays incident on the receiver, and enable the heliostat to flow the sun where it was

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