Cloudy Days Research Articles

An Improved Satellite‐Based Evapotranspiration Procedure for China

AbstractEvapotranspiration (ET) is a critical process that regulates the transfer of heat and water between land and the atmosphere. While satellite‐based ET algorithms can provide area‐wide daily ET estimates, few are independent of local meteorological measurements. The Variant of the Moderate Resolution Imaging Spectroradiometer Standard Evapotranspiration Algorithm (VISEA) can potentially run without ground‐based observations. However, the surface energy budgets used in VISEA generally overpredict daily net radiation and related ET. To improve the accuracy of net radiation and ET, we incorporated Brutsaert's atmosphere emissivity model and corrected the routine to calculate the downward long‐wave radiation on cloudy days (which we called VISEA2023 model). The VISEA2023 model predicted net radiation and ET that agreed well with measurements at seven ChinaFlux sites, with an R2 of 0.8 and an Root Mean Square Error (RMSE) of 30 W m−2 for net radiation, and an R2 of 0.6 and an RMSE of 1 mm day−1 for ET, respectively. Additionally, the VISEA2023 model is more robust in comparison to the Variable Infiltration Capacity hydrologic model output in 10 major river basins and 80 sub‐river basins, with an R2 of 0.91 (0.78) and an RMSE of 85 (127.4) mm year−1, than MOD16, which has an R2 of 0.81 (0.82) and an RMSE of 134.8 (157.7) mm year−1, and Advanced Very High Resolution Radiometer ET, which has an R2 of 0.92 (0.62) and an RMSE of 90.1 (136.1) mm year−1. The improved VISEA2023 model can offer near‐real‐time ET on a larger scale, improving our understanding of water cycles and their relation to climate change.

Enhanced natural sunlight driven photocatalytic degradation under outdoor inconstant weather by Bi2WO6/WO3 heterojunctions

Weak sunlight irradiation intensity and inconstant weather conditions limit the practical application of photocatalysis in natural environment. In this work, efficient Bi2WO6 was synthesized using surfactant assistance strategy, which possesses superior photocatalytic activity under natural environment with outdoor sunlight as illumination source. Rod-like and sheet-like WO3 were synthesized by controlling rich and poor Cl− contents in precursor solutions, respectively, which were utilized to construct Bi2WO6/WO3 heterojunctions. Compared with pristine samples, Bi2WO6/WO3 exhibit enhanced tetracycline photodegradation performance under natural environment, whether on sunny day (sunlight intensity from 44.29 to 69.48 mW/cm2) or cloudy day (from 5.07 to 54.67 mW/cm2), even overcast day (from 2.83 to 18.99 mW/cm2), and the tetracycline degradation efficiencies reached 74.3% and 54.2% within 150 min on sunny and overcast days, respectively. Moreover, Bi2WO6/WO3 exhibit the effective photodegradation performances toward methyl orange and rhodamine b, with elimination efficiencies of 63.7% and 99.0% within 50 min irradiation, respectively.

Automatic Traffic Sign Detection and Classification

Abstract: Automatic detection and recognition of road traffic signs is an essential task for regulating the traffic, guiding, and warning the drivers and pedestrians. M a n y challenges like cluttered background, foreground scenery, various geographic, metrological, weather conditions namely cloudy day, rain, snow, fog, changeable and uncontrollable lighting conditions depending on the time of the day exhibits the detection of road signs. The traffic sign may have different sizes and colors. Our goal is to detect the traffic signs with red, blue, yellow colors with any of the available shapes. Then the detected signs, combined with the color and shape information are classified. The recognition of Traffic sign involves two stages: detection stage, it finds the region consisting of traffic signs from the image and then the classification stage where the detected signs are categorized into different classes like information, warning, prohibition and so on. The image is acquired and is processed in CSR block, in which the base features from the image are extricated. The base features extricated from the image are color, shape, and Region of Interest (ROI) position. This pre-processing is very quick, because no special transformation is required. RGB and HSV color space is chosen for color segmentation. By extracting the color, CSR block creates 3 binary maps (red, blue, and yellow). From these binary maps, the shape of the traffic sign is detected. From the image the ROI is segmented, which is the input to the shape detecting block. After the shape is detected, traffic sign is classified according to its detected color and shape.

Metabolomics and Transcriptomics Analyses Reveals the Molecular Regulatory Mechanisms of Walnut (Juglans regia L.) Embryos in Response to Shade Treatment.

The walnut is an important nut that has numerous uses worldwide. However, due to dwarf and close plantation methods as well as continuous cloudy or rainy days that occur during periods of walnut oil accumulation, the walnut fruit exhibits varying degrees of stress under low-light conditions. However, the effects of shade on metabolites and genes in walnut embryos remain unclear in the literature. The purpose of this study is to investigate the lipid biosynthesis process that occurs in walnut embryos under shade treatment via the use of metabolomics and transcriptomics analyses. The results indicate that the oil content decreases significantly under shaded conditions, while the protein content increases significantly. The expression levels of fatty acid desaturase 2 (FAD2) and stearoyl-ACP-desaturase (SAD) involved in the lipid biosynthesis mechanism were significantly reduced in the shaded group, which resulted in reductions in oleic (C18:1), linoleic (C18:2), and α-linolenic (C18:3) acids. The reduced oil content was consistent with the downregulation of genes associated with the lipid biosynthesis mechanism. In the amino acid biosynthesis process, the upregulated cysteine synthase (cscK) and anthranilate synthase beta subunit 2 (trpG) genes promoted the accumulation of L-aspartic acid and L-citrulline. The increase in protein content was consistent with the upregulation of genes related to amino acid biosynthesis. Thus, our study provides new insights into the regulatory mechanisms of shade underlying overall walnut fruit quality.

Daytime radiative cooling aerogel with favorable amphiphobic surface properties

Passive daytime radiative cooling technology without any electricity input offers great promise to mitigate carbon emissions and greenhouse effects. As a type of daytime radiative cooling emitters (DRCEs), daytime radiative cooling aerogel attracts a lot of attention and has great advantages in minimizing parasitic solar absorption and reducing environmental heat gain. However, designing daytime radiative cooling aerogel with amphiphobic surface properties is still challenging. Herein, a novel daytime radiative cooling aerogel based on eco-friendly bacterial cellulose (BC) as the skeleton, modified barium sulfate (BaSO4) as functional particles and fluoride coating as amphiphobic surface modifier was developed by simple freeze-drying and spraying. The optimal daytime radiative cooling aerogel, designated as M-BC/BaSO4-14 (M-BC/BaSO4-14 refers to the modified BC/BaSO4 aerogel), exhibited a high average reflectivity (95.6%) and excellent average emissivity (98.1%). The M-BC/BaSO4-14 achieved a mean temperature drop of 6.64°C and maximum temperature drop of 13.30°C on a cloudy day, and a mean temperature drop of 8.49°C and maximum temperature drop of 12.34°C on a clear day. It should be noted that the temperature drop referred to the temperature inside the measurement box (called the inner ambient temperature throughout this article) not the true ambient temperature. Meanwhile, the M-BC/BaSO4-14 aerogel exhibited favorable amphiphobic surface properties (water contact angle of about 151°, ethylene glycol contact angle of 141° and N-Hexadecane contact angle of 139°) and daytime radiative cooling performance before and after self-cleaning changed insignificantly. This work provides a viable strategy for the simultaneous improvement of the spectral properties and amphiphobic surface properties of the DRCEs.

Non-planar dielectrics derived thermal and electrostatic field inhomogeneity for boosted weather-adaptive energy harvesting.

Weather-adaptive energy harvesting of omnipresent waste heat and rain droplets, though promising in the field of environmental energy sustainability, is still far from practice due to its low electrical output owing to dielectric structure irrationality and unscalability. Here we present atypical upcycling of ambient heat and raindrop energy via an all-in-one non-planar energy harvester, simultaneously increasing solar pyroelectricity and droplet-based triboelectricity by two-fold, in contrast to conventional counterparts. The delivered non-planar dielectric with high transmittance confines the solar irradiance onto a focal hotspot, offering transverse thermal field propagation towards boosted inhomogeneous polarization with a generated power density of 6.1mW m-2 at 0.2 sun. Moreover, the enlarged lateral surface area of curved architecture promotes droplet spreading/separation, thus travelling the electrostatic field towards increased triboelectricity. These enhanced pyroelectric and triboelectric outputs, upgraded with advanced manufacturing, demonstrate applicability in adaptive sustainable energy harvesting on sunny, cloudy, night, and rainy days. Our findings highlight a facile yet efficient strategy, not only for weather-adaptive environmental energy recovery but also in providing key insights for spatial thermal/electrostatic field manipulation in thermoelectrics and ferroelectrics.

Diversity of Flower Opening Time and Duration in Rice (Oryza sativa ssp. indica) Landraces of South and Southeast Asia in Different Cultivation Seasons

Different cultivars of rice (Oryza sativa) open at different times of the day, and the overlap of anthesis time in rice between the neighbouring cultivars is of crucial importance to the degree of cross pollination in rice. Nevertheless, none of the past experiments with cross pollination between different rice cultivars ever reported the respective flower opening time (FOT) and flower exposure duration (FED) of the parent cultivars, until recently. The authors present here the first record of FOT and FED of 1114 indica rice landraces of South and Southeast Asia, growing during summer and winter seasons in three consecutive years. The authors also present an analysis of the influences of the growing season on the anthesis behaviour, and present the first records of the FOT and FED variability on sunny and cloudy days of a large number of landraces. The data show that rice florets tend to open earlier in the morning (that is, take a shorter time to anthesis after sunrise) on sunny days than on cloudy days, and also significantly later during long day seasons (spring and summer) than during short day season (winter); and that FED is inversely related to both FOT and the length of duration from sunrise to first flower opening. The wide ranges of FOT (8:50 a.m. to 12:40 p.m.) and FED (15 to 194 minutes) also suggest the ample time window for receiving pollen from neighbouring cultivars with different FOT, enhancing the chances of cross pollination between hundreds of rice landraces with FOT and FED overlaps.

Energetic, Exergetic, and Heat Transfer Assessment of PCM-Integrated Heat-Pipe-Based ETSC for Clear and Cloudy Weather Conditions

Solar energy’s most promising application is in water heating, followed by other solar thermal applications. In this investigation, a novel method of incorporating a phase-change material (PCM) between the annulus space of an evacuated tube and an aluminum finned heat pipe is employed. During day time, the PCM stores the excess amount of heat and releases it in order to heat the flowing water during high-demand/insufficient solar radiation. This study aims to evaluate the detailed heat transfer assessment and energetic and exergetic efficiencies of the developed PCM-integrated solar water heater in both clear and cloudy weather conditions at 20 LPH. The outcomes of the study found that the maximum useful amounts of energy collected daily for the clear and cloudy days were 10.65 MJ and 8.52 MJ, respectively, whereas temperatures of the stored water were found to be 45.2 °C and 41.4 °C on the next day at 6:00 a.m. for the corresponding days. The daily energetic and exergetic outputs of the designed system were 76.57% and 79.64%, and 2.37% and 1.38%, respectively, at fixed mass flow rate for the clear and cloudy day conditions. The overall heat transfer coefficients (UL) for both days were 0.75 and 0.72 W/m2 K, respectively. The findings show that the proposed system overcomes the issue of overheated heat pipes and can provide hot water even in cloudy/low-sunshine conditions.

INVESTIGATION OF THE USE OF A HEATER WITH A CARBON FIBER HEAT-GENERATING FLEXIBLE MATERIAL AND A SOLAR STATION

In remote areas, the premises of mobile dwellings are heated by traditional fuel stoves. This includes mobile homes for farmers and field workers. However, a problem with the fuel supply may arise when the mobile home is located at a significant distance from the settlement. Thus, it is possible to use solar energy for heating mobile homes. For space heating, a study was conducted using a heater with carbon fiber heat-generating flexible material and a solar station. Solar energy is used to generate electricity, which will be used to power the heating element. The aim of the study is to develop and implement a heating system using solar energy for mobile dwellings of workers in transhumance and crop production. This space heating system is recommended for use on cool summer days and for heating in winter as an addition to the main traditional heating. For further research, it is necessary to search for other heating devices with lower power consumption, the best option would be consumption in the range of 100 - 200 W. There is also the issue of upgrading solar stations to generate electricity on cloudy days.

Outdoor Thermal Environment Regulation of Urban Green and Blue Infrastructure on Various Types of Pedestrian Walkways

Urban green and blue infrastructure (GBI) is effective in urban heat mitigation. However, the diurnal variations in the thermal regulation of GBI on different types of urban pedestrian walkways in the subtropical humid climate zone are unclear. Based on traverse measurements in January 2022, this study investigates how outdoor air temperature (Ta) and wet-bulb temperature (Tw) at the pedestrian level are affected by various urban morphology and GBI characteristics in the central urbanized area of Guangzhou (China). Six building-related, three vegetation-related, and three water-related parameters were applied in the analyses. Results show that green infrastructure (GI) has the strongest cooling effect (Pearson’s coefficient r = −0.33~−0.54) on Ta on cloudy evenings and the weakest cooling effect (r = −0.22~−0.32) on clear evenings. Blue infrastructure (BI) exhibits the highest correlations with the cooling effect for Ta on clear afternoons (r = −0.35~−0.51) and weaker, but more consistent, correlations throughout cloudy days (r = −0.23~−0.43). Strong correlations between GI and Tw cooling are observed in the morning and evening on clear days (r = −0.13~−0.48), while BI exhibits the strongest correlation with Tw cooling on clear afternoons (r = −0.13~−0.37). In addition, both GI and BI show a greater cooling effect on both Ta and Tw in low-rise areas compared to high-rise areas. Compared to the individual GI or BI, the integrated GBI has a higher cooling intensity for both Ta and Tw in high-rise areas. However, the cooling potential of integrated GBI is slightly lower for both Ta and Tw during noon and afternoon in low-rise areas. The findings of this study give insights into urban GBI planning and design of specific urban microclimate regulation strategies.

Study on An Effective Roadway Watering Scheme for Mitigating Pedestrian Thermal Comfort According to the Street Configuration

Continuous measurement of road surface temperature using an infrared camera throughout the summer season was conducted to clarify the duration of surface temperature decrease due to roadway watering according to weather conditions and watering time. Watering during sunny daytime conditions resulted in a maximum reduction in surface temperature of about 10 °C and an average reduction of about 6 °C. The duration of the surface temperature decrease was short (less than 30 min) for sunny days and long (more than 30 min) for cloudy days. On sunny days, if the evaporation rate was faster and the surface temperature decrease was larger, then the duration of the evaporation was shorter. Effective roadway watering plans were investigated according to the street configurations by simulating the thermal environment considering the solar radiation shielding condition of pedestrians on sidewalks. Simulation results in the downtown area of Kobe city indicated that watering the nearby roadways resulted in only 20% and 39% comfort for the northern sidewalks on the east–west road at 10:00 and 16:00, but about 70% comfort for the southern sidewalks and 60–90% comfort for the eastern and western sidewalks. Guiding pedestrians to a shaded sidewalk and then watering the nearby roadway to lower the surface temperature in the sun improves the thermal environment for pedestrians.

Solar irradiance prediction in the tropics using a weather forecasting model

Prediction of photovoltaic (PV) system generations is a powerful tool for managing the electric grids with multiple PV systems for reducing the instability of their electricity supply. For the prediction, solar irradiance, which is directly related to PV generation is forecasting using a weather forecasting model in this study. The target country, Thailand, is in the tropical zone. In the tropics, cumulus and cumulonimbus appear frequently, and their behavior makes weather forecasting difficult. The correlations of the forecasted irradiances with the observations are about 0.8 or more in the intra-day, next-day, and 2-day ahead forecastings. It shows that the validity of solar irradiance forecasting in the tropics for the prediction of PV output. On cloudy days, the tendency of the fluctuation of solar irradiance is reproduced well in the forecasting, but a phase of the fluctuation is shifted in the forecasting.

An improved numerical model to predict the operating temperature and efficiency of solar photovoltaic systems.

Solar photovoltaic (PV) technology has a huge potential for producing renewable energy and reducing greenhouse gas emissions. An increase in the PV cell temperature in real operating conditions reduces the actual output of a solar PV system. A 1D transient multi-layered model, based on the fundamentals of the finite difference method, has been developed to predict the operating cell temperature. Since a PV system operates in stochastic wind conditions and is not subjected to any predefined thermal boundary condition, several expressions of convection coefficient have been scientifically analyzed to determine the most suitable expression. The novel calculation approach assumes explicit radiation terms and implicit convection terms to linearize the equations and get rid of any iterative process. Comparison with experimental results shows that the convection coefficient derived from boundary layer theory corresponding to uniform heat flux predicts the cell temperature with the best accuracy showing a mean error of only [Formula: see text] and [Formula: see text]. Splitting the heat source across different solar PV layers produces a maximum change of [Formula: see text] only and can be avoided due to the involved complexity. The study proposes a new piece-wise function for PV efficiency in terms of cell temperature and irradiation. This novel function predicts PV efficiency on a sunny and a cloudy day with [Formula: see text] and [Formula: see text] mean errors, respectively, which are considerably lower than errors obtained using other popular functions in the literature. The model helps in predicting actual output from a PV system more accurately which should enable taking more informed decisions regarding the location of installation, PV technology, and the need for a cooling method.

Effects of fishery complementary photovoltaic power plant on radiation, energy flux and driving forces under different synoptic conditions

The underlying surface was the important media of air-lake interaction by transferring energy. The deployment of photovoltaic arrays on the lake has formed a new underlying surface type. But the new underlying surface is different from the natural lake. The impact of fishery complementary photovoltaic (FPV) power plants on the radiation, energy flux, and driving force is unclear. Therefore, the analysis of radiation, energy flux, and driving force by comparing the difference in the two sites under various synoptic conditions. The results indicated that the radiation components are not significantly different in the two sites under diverse synoptic conditions. The downward shortwave radiation (DSR) and net radiation ({R}_{n}) were presented with one peak on a sunny day. The daily average DSR and Rn in the two sites were 279.1 W·m−2, 209.3 W·m−2, respectively. The daily average (cloudy day and rainy day) sensible heat flux in the two sites was 39.5 W·m−2 (FPV site), 19.2 W·m−2 (REF site), respectively. The latent heat flux was 53.2 W·m−2 and 75.2 W·m−2 on counterpart. The water body generally absorbs heat from the air (daily average ∆Q was 16.6 W·m−2) in the FPV site on a sunny day. The driving force of sensible heat flux in the FPV site was governed by the temperature of the FPV panel under sunny and cloudy conditions. The latent heat flux was determined by the product between wind speed and water-atmosphere temperature difference.

Research on echo characteristics in remote detection with the pulse LiDAR of aerial targets under diverse atmospheric conditions

This paper utilizes the idea of theoretical analysis to introduce a method for echo characteristics in remote detection with the pulse LiDAR of aerial targets under atmospheric conditions. A Missiles and an aircraft are selected as simulation targets. The relation among mutual mapping of target surface elements can be directly gained by setting light source and target parameters. We discuss influences on atmospheric transport conditions, target shapes and detection conditions on echo characteristics. Atmospheric transport model is introduced as weather conditions, including sunny and cloudy days, with or without turbulence. Simulation results conclude that the outline of scanned waveform can invert the target shape. These provide a theoretical basis for improving the target detection and tracking performance.

The impact of variable illumination on vegetation indices and evaluation of illumination correction methods on chlorophyll content estimation using UAV imagery

BackgroundThe advancements in unmanned aerial vehicle (UAV) technology have recently emerged as an effective, cost-efficient, and versatile solution for monitoring crop growth with high spatial and temporal precision. This monitoring is usually achieved through the computation of vegetation indices (VIs) from agricultural lands. The VIs are based on the incoming radiance to the camera, which is affected when there is a change in the scene illumination. Such a change will cause a change in the VIs and subsequent measures, e.g., the VI-based chlorophyll-content estimation. In an ideal situation, the results from VIs should be free from the impact of scene illumination and should reflect the true state of the crop’s condition. In this paper, we evaluate the performance of various VIs computed on images taken under sunny, overcast and partially cloudy days. To improve the invariance to the scene illumination, we furthermore evaluated the use of the empirical line method (ELM), which calibrates the drone images using reference panels, and the multi-scale Retinex algorithm, which performs an online calibration based on color constancy. For the assessment, we used the VIs to predict leaf chlorophyll content, which we then compared to field measurements.ResultsThe results show that the ELM worked well when the imaging conditions during the flight were stable but its performance degraded under variable illumination on a partially cloudy day. For leaf chlorophyll content estimation, The r^2 of the multivariant linear model built by VIs were 0.6 and 0.56 for sunny and overcast illumination conditions, respectively. The performance of the ELM-corrected model maintained stability and increased repeatability compared to non-corrected data. The Retinex algorithm effectively dealt with the variable illumination, outperforming the other methods in the estimation of chlorophyll content. The r^2 of the multivariable linear model based on illumination-corrected consistent VIs was 0.61 under the variable illumination condition.ConclusionsOur work indicated the significance of illumination correction in improving the performance of VIs and VI-based estimation of chlorophyll content, particularly in the presence of fluctuating illumination conditions.

Weather influence on the performance of solar collector

A laboratory-scale evacuated tube solar collector (ETSCs) has been developed and tested for unloading conditions in Lanzhou, China. clear sky and cloudy conditions have been tested. Heat is generally considered instantaneous because it is a function of multiple instantaneous factors, like ambient temperature and solar radiation. The results show a clear sky day with a maximum and average value of ambient temperature, outlet, inlet, and solar radiation of 12 and -60C, 56 and 310C, 69 and 340C, 931 and 576W/m2, respectively, while a cloudy day was eight and -30C and 861.2 and 449W/m2 respectively. Clear sky day maximum and the average mass flow rate was 0.25 and 0.21 Kg/sec, while the cloudy flow rate was 0.27 and 0.03 Kg/sec, respectively. A clear sky has a heat loss of -0.307 and -0.05kW for a cloudy day. R square were 0.76 and 0.4 for clear sky and cloudy day, respectively. For the heat and radiation correlation relationship, a clear sky has a slope of 0.0029 and 0.0539 for a cloudy day. In other conditions, the solar radiation per unit area increases by 1 W/m2, and the daily heat is collected. Increasing A W/m2, the temperature difference between the average temperature of the hot water storage tank and the average temperature of the environment increases by one °C, and the daily heat collection decreases A W/m2. It concludes that a clear sky has much better efficiency than a cloudy day.

Voltage Regulation Planning Based on Optimal Grid-Connected Renewable Energy Allocation Using Nature-Inspired Algorithms to Reduce Switching Cycles of On-Load Tap Changing Transformer

Due to the non-deterministic and probabilistic qualities of renewable energy resources (RER), integrating these resources has posed a challenge for energy companies and government policy planners. Hybrid power systems require frequent voltage regulation to address the changes in renewable generation and facilitate voltage management. This leads to an increment in the operating time of the tap changer in the power transformer, thus resulting in accelerated degradation of the on-load tap changer (OLTC) device. The primary focus of this paper is to optimally manage the penetration level of renewable generation while maintaining the minimum time for proper operation of voltage regulation devices. Accordingly, the major contribution of this paper is to address the switching cycle issues of the on-load tap-changing transformer. Initially, a framework is proposed to optimize the location and size of renewable power generation using a multi-objective cuckoo search optimization algorithm. The main goal here is to reduce power losses and tap changer operations while improving the system voltage profile under different levels of renewable energy penetration. The optimization problem takes into consideration the fluctuating nature of wind speed and solar irradiance for sunny and cloudy days over 24 h. The framework has been applied to the IEEE 57-bus and 118-bus systems with different load levels. The performance of the proposed approach has been benchmarked by comparing it with the genetic optimization algorithm to identify the higher potential buses for renewable generation allocation. The cuckoo search algorithm (CSA) shows outstanding results in reducing the number of switching cycles to about (37 – 43) % whereas the genetic algorithm (GA) only (17 – 18). In this sense, the number of changes in tap position when using the CSA is 1956 for sunny days and 1763 for cloudy days compared to GA 2558 for sunny days and 2547 for cloudy days. The voltage profiles for both algorithms are maintained in the range of (1.06 and 0.94) per unit. The results affirm the effectiveness of the proposed approach in determining the optimal placement and size of RER with voltage profile improvement and reduction in the switching cycles of OLTC.

Retrieval of particle size distribution based on a multi-objective genetic algorithm for multi-wavelength lidar

Introduction: Aerosols affect the radiation budget of the Earth’s atmospheric system. The aerosol particle size distribution (PSD) is one of the main parameters for characterizing the effect of aerosol on radiative forcing.Methods: The extinction coefficient and backscattering coefficient at 355 and 532 nm and backscattering coefficient at 1064 nm of aerosol particles over Yinchuan area, China, which measured by a multi-wavelength lidar developed by North Minzu University, were used to retrieve the aerosol PSD. In view of the disadvantages of traditional regularization methods, the elitist Non-Dominated Sorting Genetic Algorithm (NSGA-II) is selected to retrieve PSD.Results and Discussion: To verify the feasibility for retrieval of aerosol PSD, the NSGA-II with different errors in the input optical signal was simulated, in which the errors of the inverted PSD are still in the acceptable range when 35% error added into the optical parameters. Moreover, some experiments were carried out under different atmospheric conditions, including background sunny, cloudy and dusty days, and comparisons were performed with Multiple Population Genetic Algorithm (MPGA) and Simple Genetic Alogrithm (SGA) method. The results show that the retrieval effect of NSGA-II was better than that of MPGA and SGA, and the NSGA-II is very suitable for retrieve PSD by using the multi-wavelength lidar data.

Storage periods and heating terminals types influence on the solar heating thermal storage volume in the Tibetan Plateau regions

The scale of the thermal storage system is critical to balancing system fluctuations caused by the mismatch between solar heat collection and heating load in time and space for solar heating systems. This study investigates the relationship between solar collector area and heat storage volume under the different storage periods and heating terminals types. This research simulates the heat storage volumes using a typical day, continuous overcast days, and heating period as thermal storage periods, based on solar radiation intensity, building heating load, and cloudy days in seven typical Tibetan regions. According to the results, the storage volume per unit collector area Vs/Ac increases with increasing temperature difference and storage period in the Tibetan Plateau. It is proposed that Lhoka, Chamdo, Nagqu, Lhasa, Shigatse, and Nyingchi take continuous overcast and cloudy days as thermal storage periods, and Ngari uses the heating period as thermal storage periods, corresponding to the Vs/Ac ranges of 0.27 m3/m2–0.9 m3/m2 and 1.6 m3/m2–1.8 m3/m2. Specifically, preheating the heat storage tank can improve the solar fraction fsim by 2.5 %, with the recommended preheating temperature of 50 °C. In addition, the variation equation for design solar fraction fn and Vs/Ac was obtained. These results can be utilized to develop solar heating systems on the Tibetan plateau.