Maintaining a steady power supply requires accurate forecasting of solar irradiance,since clean energy resources do not provide steady power.The existing forecasting studies have examined the limited effects of weathe...Maintaining a steady power supply requires accurate forecasting of solar irradiance,since clean energy resources do not provide steady power.The existing forecasting studies have examined the limited effects of weather conditions on solar radiation such as temperature and precipitation utilizing convolutional neural network(CNN),but no comprehensive study has been conducted on concentrations of air pollutants along with weather conditions.This paper proposes a hybrid approach based on deep learning,expanding the feature set by adding new air pollution concentrations,and ranking these features to select and reduce their size to improve efficiency.In order to improve the accuracy of feature selection,a maximum-dependency and minimum-redundancy(mRMR)criterion is applied to the constructed feature space to identify and rank the features.The combination of air pollution data with weather conditions data has enabled the prediction of solar irradiance with a higher accuracy.An evaluation of the proposed approach is conducted in Istanbul over 12 months for 43791 discrete times,with the main purpose of analyzing air data,including particular matter(PM10 and PM25),carbon monoxide(CO),nitric oxide(NOX),nitrogen dioxide(NO_(2)),ozone(O₃),sulfur dioxide(SO_(2))using a CNN,a long short-term memory network(LSTM),and MRMR feature extraction.Compared with the benchmark models with root mean square error(RMSE)results of 76.2,60.3,41.3,32.4,there is a significant improvement with the RMSE result of 5.536.This hybrid model presented here offers high prediction accuracy,a wider feature set,and a novel approach based on air concentrations combined with weather conditions for solar irradiance prediction.展开更多
Accurate measurements of upwelling irradiance just beneath the ocean surface,E_(u)(λ,0^(-)),can be used to calculate ocean optical parameters,and further develop retrieval algorithms for remotely sensing water compon...Accurate measurements of upwelling irradiance just beneath the ocean surface,E_(u)(λ,0^(-)),can be used to calculate ocean optical parameters,and further develop retrieval algorithms for remotely sensing water component concentrations.Due to the effects of sea surface waves,perturbation from instrument platform(ship),and instrument self-shading,E_(u)(λ,0^(-))is often difficult to be accurately measured.This study presents a procedure for extrapolating the E_(u)(λ,0^(-))from the in-water radiometric profile measurements.Using the optical profile data from 13 bands(ranging from 381 to 779 nm)measured by 45 casts in the Ligurian Sea during 2003–2009,the E_(u)(λ,0^(-))was extrapolated from in-water upwelling irradiance measurements between the initial shallow depth,Z_(0),and an optimal bottom depth,Z_(1),by three linear models(linear,2-degree polynomial,and exponential)and two nonlinear models(LOESS and spline).The accumulated errors of extrapolated E_(u)(λ,0^(-))at each wavelength for the five models were calculated.It was found that the optimal Z_(1) depth for the linear and exponential models was at the depth of80%of E_(u)(λ,Z_(0)),50%of E_(u)(λ,Z_(0))for the 2-degree polynomial model,40%of E_(u)(λ,Z_(0))for the LOESS model,and 15%of E_(u)(λ,Z_(0))for the spline model.The extrapolated E_(u)(λ,0^(-))derived from the five models was in good agreement with the calculated true E_(u)(λ,0^(-)).In all bands,the 2-degree polynomial model achieved the highest accuracy,followed by the LOESS model.In the short band of 381–559 nm,the linear and exponential models had the third-best performance,and the spline model performed worst within this range.For the red band of 619–779 nm,the accuracies of the exponential and spline models had the third highest performance,and the linear model produced lowest accuracy.Hence,the 2-degree polynomial model was an optimal procedure for extrapolation of E_(u)(λ,0^(-))from the in-water radiometric profile measurements.展开更多
Increasing global energy consumption has become an urgent problem as natural energy sources such as oil,gas,and uranium are rapidly running out.Research into renewable energy sources such as solar energy is being purs...Increasing global energy consumption has become an urgent problem as natural energy sources such as oil,gas,and uranium are rapidly running out.Research into renewable energy sources such as solar energy is being pursued to counter this.Solar energy is one of the most promising renewable energy sources,as it has the potential to meet the world’s energy needs indefinitely.This study aims to develop and evaluate artificial intelligence(AI)models for predicting hourly global irradiation.The hyperparameters were optimized using the Broyden-FletcherGoldfarb-Shanno(BFGS)quasi-Newton training algorithm and STATISTICA software.Data from two stations in Algeria with different climatic zones were used to develop the model.Various error measurements were used to determine the accuracy of the prediction models,including the correlation coefficient,the mean absolute error,and the root mean square error(RMSE).The optimal support vector machine(SVM)model showed exceptional efficiency during the training phase,with a high correlation coefficient(R=0.99)and a low mean absolute error(MAE=26.5741 Wh/m^(2)),as well as an RMSE of 38.7045 Wh/m^(2) across all phases.Overall,this study highlights the importance of accurate prediction models in the renewable energy,which can contribute to better energy management and planning.展开更多
[Objective] The study aimed to prove effects of NO on oxidative damage and photosynthetic apparatus at filling stage of wheat leaves under high temperature and irradiance stress.[Method] Yunong 949 was taken as experi...[Objective] The study aimed to prove effects of NO on oxidative damage and photosynthetic apparatus at filling stage of wheat leaves under high temperature and irradiance stress.[Method] Yunong 949 was taken as experimental material to study the effects of sodium nitropprusside (SNP,an exogenous nitric oxide donor) at 0.1 mmol/L on protective enzyme activities, oxidative damage and fluorescence.[Result] The treatment with SNP (at 0.1 mmol/L) significantly increased the activity of SOD and APX, proline content, decreased the MDA content and relative electrical conductivity, Kept the higher Fv/Fm and lower Fo.[Conclusion] The adaptability of wheat with SNP treatment at 0.1 mmol/L was improved under high temperature and irradiance stress.展开更多
The focusing tomography is presented to reconstruct 3 dimensional irradiance distribution. A 3 dimensional luminous body could be considered as the combination of many 2 dimensional parallel luminous sections. Focu...The focusing tomography is presented to reconstruct 3 dimensional irradiance distribution. A 3 dimensional luminous body could be considered as the combination of many 2 dimensional parallel luminous sections. Focus on these discrete sections respectively by a single camera, a group of images would be captured to form governing equations of irradiance. After inversion procedure, the irradiance distribution of different sections could be decoded. In this experimentation two lightbulbs are used to simulate two luminous sections. Reasonable results demonstrate that this technique could be a useful method in irradiance reconstruction after further development.展开更多
Blooms of Phaeocystis globosa have been frequently reported in Chinese coastal waters, causing serious damage to marine ecosystems. To better understand the ecological characteristics of P. globosa in Chinese coastal ...Blooms of Phaeocystis globosa have been frequently reported in Chinese coastal waters, causing serious damage to marine ecosystems. To better understand the ecological characteristics of P. globosa in Chinese coastal waters that facilitate its rapid expansion, the effects of temperature, salinity and irradiance on the growth of P. globosa from the South China Sea were examined in the laboratory. The saturating irradiance for the growth ofP. globosa （Is） was 60 μmol/（m^2·s）, which was lower than those of other harmful algal species （70-114μmol/（m^2·s））. A moderate growth rate of 0.22/d was observed at 2 μmol/（m^2·s） （the minimum irradiance in the experiment）, and photo-inhibition did not occur at 230 μmol/（m^2·s） （the maximum irradiance in the experiment）. Exposed to 42 different combinations of temperatures （10- 31 ℃） and salinities （10-40） under saturating irradiance, P. globosa exhibited its maximum specific growth rate of 0.80/d at the combinations of 24℃ and 35, and 27℃ and 40. The optimum growth rates （〉0.80/d） were observed at temperatures ranging from 24 to 27℃ and salinities from 35 to 40. While P. globosa was able to grow well at temperatures from 20℃ to 31℃ and salinities from 20 to 40, it could not grow at temperatures lower than 15℃ or salinities lower than 15. Factorial analysis revealed that temperature and salinity has similar influences on the growth of this species. This strain ofP. globosa not only prefers higher temperatures and higher salinity, but also possesses a flexible nutrient competing strategy, adapted to lower irradiance. Therefore, the P. globosa population from South China Sea should belong to a new ecotype. There is also a potentially high risk of blooms developing in this area throughout the year.展开更多
factor experiment was used to study the combined effects of temperature, irradiance and salinity on the growth of an HAB species diatom Skeletonema costatum (Grev.) Cleve. The results showed that temperature (12, 19, ...factor experiment was used to study the combined effects of temperature, irradiance and salinity on the growth of an HAB species diatom Skeletonema costatum (Grev.) Cleve. The results showed that temperature (12, 19, 25, 32℃), irradiance ((0.02, 0.08, 0.3, 1.6)×10 16 quanta/(s·cm 2)) and salinity (10, 18, 25, 30, 35) significantly influenced the growth of this species. There were interactive effects between any two of and among all three physical factors on the growth. In the experiment, the most optimal growth condition for S. costatum was temparature of 25℃, salinity of 18-35 and irradiance of 1.6×10 16 quanta/(s·cm 2). The results indicated S. costatum could divide at higher rate and were more likely to bloom under high temperature and high illumination from spring to fall. It was able to distribute widely in ocean and estuary due to its adaptation to a wide range of salinities.展开更多
Chondrus is a type of commercially produced red seaweed that widely used for food and carrageen extraction. Although the natural life history of the alga had been well understood, the factors influencing development o...Chondrus is a type of commercially produced red seaweed that widely used for food and carrageen extraction. Although the natural life history of the alga had been well understood, the factors influencing development of the tetraspore and carpospore remain poorly understood. In the perspective of seedling resources, the regulation of early development is crucial for the seedlillg nursing; therefore, it is necessary to understand the physiological influences during its early development. In this study, we studied the effects of temperature and irradiance on the early development of Chondrus ocellatus Holm under laboratory conditions. The released tetraspores and carpospores were cultivated at different temperatures （10-28℃） and irradiances （10, 60 μmol photons m^-2s^-1） with a photoperiod of 12L： 12D. The results indicate that both tetraspores and carpospores are tolerant to temperatures of 10-25℃, and have the highest relative growth rate at 20℃. Irradiance variances influenced the growth of the discoid crusts, and the influence was more significant with increasing temperature; 60 μmol photons m^-2s^-1 was more suitable than 10 μmol photons m^-2s^-1. The optimum temperature and irradiance for the development of seedlings was 20℃ and 60 μmol photons m^-2s^-1, respectively.展开更多
Solar radiation pressure is the main driving force and error source for precision orbit determination of navigation satellites.It is proportional to the solar irradiance,which is the"sun constant".In regular...Solar radiation pressure is the main driving force and error source for precision orbit determination of navigation satellites.It is proportional to the solar irradiance,which is the"sun constant".In regular calculation,the"solar constant"is regard as a constant.However,due to the existence of sunspots,flares,etc.,the solar constant is not fixed,the change in the year is about 1%.To investigate the variation of solar irradiance,we use interpolation and average segment modeling of total solar irradiance data of SORCE,establishing variance solar radiation pressure(VARSRP)model and average solar radiation pressure(AVESRP)model based on the built solar pressure model(SRPM)(constant model).According to observation data of global positioning system(GPS)and Beidou system(BDS)in 2015 and comparing the solar pressure acceleration of VARSRP,AVESRP and SRPM,the magnitude of change can reach 10-10 m/s^2.In addition,according to the satellite precise orbit determination,for GPS satellites,the results of VARSRP and AVESRP are slightly smaller than those of the SRPM model,and the improvement is between 0.1 to 0.5 mm.For geosynchronous orbit(GEO)satellites of BDS,The AVESRP and VARSRP have an improvement of 3.5 mm and 4.0 mm,respectively,based on overlapping arc,and SLR check results show the AVESRP model and the VARSRP model is improved by 2.3 mm and 3.5 mm,respectively.Moreover,the change of inclined geosynchronous orbit(IGSO)satellites and medium earth orbit(MEO)satellites is relatively small,and the improvement is smaller than 0.5 mm.展开更多
Current freeform illumination optical designs are mostly focused on producing prescribed irradiance distributions on planar targets.Here,we aim to design freeform optics that could generate a desired illumination on a...Current freeform illumination optical designs are mostly focused on producing prescribed irradiance distributions on planar targets.Here,we aim to design freeform optics that could generate a desired illumination on a curved target from a point source,which is still a challenge.We reduce the difficulties that arise from the curved target by involving its varying z-coordinates in the iterative wavefront tailoring(IWT)procedure.The new IWT-based method is developed under the stereographic coordinate system with a special mesh transformation of the source domain,which is suitable for light sources with light emissions in semi space such as LED sources.The first example demonstrates that a rectangular flat-top illumination can be generated on an undulating surface by a spherical-freeform lens for a Lambertian source.The second example shows that our method is also applicable for producing a non-uniform irradiance distribution in a circular region of the undulating surface.展开更多
An important population of the dayside Martian ionosphere are photoelectrons that are produced by solar Extreme Ultraviolet and X-ray ionization of atmospheric neutrals.A typical photoelectron energy spectrum is chara...An important population of the dayside Martian ionosphere are photoelectrons that are produced by solar Extreme Ultraviolet and X-ray ionization of atmospheric neutrals.A typical photoelectron energy spectrum is characterized by a distinctive peak near 27 eV related to the strong solar HeⅡ emission line at 30.4 nm,and an additional peak near 500 eV related to O Auger ionization.In this study,the extensive measurements made by the Solar Wind Electron Analyzer on board the recent Mars Atmosphere and Volatile Evolution spacecraft are analyzed and found to verify the scenario that Martian ionosphere photoelectrons are driven by solar radiation.We report that the photoelectron intensities at the centers of both peaks increase steadily with increasing solar ionizing flux below 90 nm and that the observed solar cycle variation is substantially more prominent near the O Auger peak than near the HeⅡ peak.The latter observation is clearly driven by a larger variability in solar irradiance at shorter wavelengths.When the solar ionizing flux increases from 1 mW·m^-2 to 2.5 mW·m^-2,the photoelectron intensity increases by a factor of 3.2 at the HeⅡ peak and by a much larger factor of 10.5 at the O Auger peak,both within the optically thin regions of the Martian atmosphere.展开更多
Currently,polarization visualization strategies are accomplished by mapping polarization information into a perceptually uniform color appearance model CAM02-UCS.However,the deviation of the CAM02-UCS space from the l...Currently,polarization visualization strategies are accomplished by mapping polarization information into a perceptually uniform color appearance model CAM02-UCS.However,the deviation of the CAM02-UCS space from the lightness prediction results in an inaccurate match between the polarization information and the perceptual information.In this paper,we propose a novel polarization visualization strategy based on the perceptual uniform space Jzazbz.The polarization visualization be completed by placing the polarization information into the lightness Jz,colorfulness Cz and hue angle hz channels of the Jzazbz space.The experimental results show that the proposed method can significantly improve the lightness of the low irradiance and high polarization region,hence more polarization information can be sensed by human visual system.展开更多
Surface irradiance measurements with high temporal resolution can be used to detect clear skies,which is a critical step for further study,such as aerosol and cloud radiative effects.Twenty-one clear-sky detection(CSD...Surface irradiance measurements with high temporal resolution can be used to detect clear skies,which is a critical step for further study,such as aerosol and cloud radiative effects.Twenty-one clear-sky detection(CSD)methods are assessed based on five years of 1-min surface irradiance data at Xianghe—a heavily polluted station on the North China Plain.Total-sky imager(TSI)discrimination results corrected by manual checks are used as the benchmark for the evaluation.The performance heavily relies on the criteria adopted by the CSD methods.Those with higher cloudy-sky detection accuracy rates produce lower clear-sky accuracy rates,and vice versa.A general tendency in common among all CSD methods is the detection accuracy deteriorates when aerosol loading increases.Nearly all criteria adopted in CSD methods are too strict to detect clear skies under polluted conditions,which is more severe if clear-sky irradiance is not properly estimated.The mean true positive rate(CSD method correctly detects clear sky)decreases from 45%for aerosol optical depth(AOD)≤0.2%to 6%for AOD>0.5.The results clearly indicate that CSD methods in a highly polluted region still need further improvements.展开更多
In order to investigate the burning characteristics of a 0#diesel and 3#jet fuel,a small-scale experimental bench mainly composed of a cone calorimeter was arranged.The heat release and burning rates were investigated...In order to investigate the burning characteristics of a 0#diesel and 3#jet fuel,a small-scale experimental bench mainly composed of a cone calorimeter was arranged.The heat release and burning rates were investigated changing the external irradiance in order to clarify the triadic relationship among these quantities.The effective heat of combustion of 0#diesel and 3#jet fuel were 38.89 MJ/kg and 43.15 MJ/kg,respectively,with the corresponding combustion efficiencies being 96.78%and 99.60%(the effective peak heat of combustion being 1.665 times the mean value for both types of fuel).According to our experimental results,the heat release rate and burning rate of 0#diesel and 3#jet fuel both grow linearly with an increase in the external irradiance.Moreover,the heat release rate and burning rate of 3#jet fuel are greater than the equivalent values for the 0#diesel.The average smoke production rate of 0#diesel grows with an increase in the external irradiance,while for the 3#jet fuel it remains approximately the same.The specific extinction area of these two kinds of fuel shows a subtle decrease with the increase of external irradiance.The time to ignition of 3#jet fuel is smaller than 0#diesel for all the considered external irradiances,which indicates that 3#jet fuel is easier to ignite than the 0#diesel.展开更多
The solar UV radiation has prominent impacts on human life, animals and plants with positive and negative effects. Atmospheric ozone, which is formed from the photodissociation of molecular oxygen mainly in the strato...The solar UV radiation has prominent impacts on human life, animals and plants with positive and negative effects. Atmospheric ozone, which is formed from the photodissociation of molecular oxygen mainly in the stratosphere, absorbs a significant factor of solar UV radiation. The ozone in the stratosphere acts as a protective layer to prevent UV radiation reaching on the surface of the earth. Hence the intensity of solar UV radiation on the surface has a strong dependence on the Total Ozone Column (TOC). The UV irradiance on earth surface depends on geometrical factors such as solar zenith angle, altitude, latitude and other atmospheric parameters as well. This is an attempt to study the variation of solar UV flux at its four discrete wavelengths ranging from 305 - 380 nm at Kannur, which is located in the north of Kerala in India. Hence such a correlation of TOC and UV irradiance is relevant to realize the radiation budget at this location (12.3N, 75.4E) using AURA OMI data. This paper reveals the correlation of day to day, month to month temporal variation of total ozone column (in DU) and UV irradiance (w/m2). From the analysis, the anti-correlation between UV and TOC is revealed and its impact in the solar radiation budget is established.展开更多
The light is one of the important factors for the microalgae growth in the biofuel technology. As biofuel project is large and expensive thus before setting a microalgae based biofuel project in any geographical locat...The light is one of the important factors for the microalgae growth in the biofuel technology. As biofuel project is large and expensive thus before setting a microalgae based biofuel project in any geographical location, it is important to investigate the suitability of all important parameters involving with the system. This paper aims to investigate the sunlight availability and the microalgae growth for a photobioreactor at Chittagong University of Engineering and Technology (CUET). A computational growth model related to the average irradiance is proposed to calculate the growth of microalgae. We observed that average irradiance is the highest in June and is the lowest in December. From our simulation it is found that the growth of microalgae varies with the average irradiance in a year.展开更多
In our trials, from 2007 to 2008, of mass production of seedlings of Hizikiafusiformis using synchronization techniques, problems of a ＂dark thalli＂ phenomenon and epiphytes contamination severely threatened the hea...In our trials, from 2007 to 2008, of mass production of seedlings of Hizikiafusiformis using synchronization techniques, problems of a ＂dark thalli＂ phenomenon and epiphytes contamination severely threatened the health of juvenile seedlings. In this investigation, we optimized conditions for improving the growth of juvenile seedlings. Seven string collectors were seeded with zygotes and a series of experiments were conducted including direct exposure to solar irradiance, co-culture with Ulva spp. and treatment with sodium hypochlorite. It was found that direct exposure to solar irradiance （maximum： 1 740 μmol photons/（m2.s）） for 2 h per day could efficiently enhance the growth of young seedlings and simultaneously inhibit the growth of epiphytic algae. In this treatment, 50-day old seedlings could reach an average of 0.44 cm in length and possess up to nine leaflets. However, a single treatment with 18-mmol/L sodium hypochlorite for 10 rain severely harmed 15-day old seedlings. In comparison, weekly treatment with 2.2-mmol/L sodium hypochlorite for 10 rain brought no apparent harm to seedlings and eliminated epiphytic algae efficiently. However, this treatment significantly increased the detachment rate of seedlings, Inoculating Ulva spp. onto the collector caused a dramatic decrease in the number of seedlings. However, the growth of the remaining seedlings appeared unhampered. All collectors except the control were daily sprayed with a high pressure water jet from the 84 day post fertilization. From the first day to 50th day, no ＂dark thallus＂ was observed on any of the seven collectors. We believe that well-timed daily exposure to solar irradiance would favor H. fusiformis in its early growing stages.展开更多
Understanding the embryo physiology of Hizikia fusiformis（Harvey） Okamura will promote the development of artificial seedlings. In this study, H. fusiformis embryos were cultured under different environmental condit...Understanding the embryo physiology of Hizikia fusiformis（Harvey） Okamura will promote the development of artificial seedlings. In this study, H. fusiformis embryos were cultured under different environmental conditions, including different temperatures（15℃, 20℃, and 25℃）, sunlight intensities（100%, 50%, and 25% of full solar radiation） and types of UVR（UV-A and UV-B）. Then, we determined the lengths, maximal quantum yields（ Fv/Fm）, and survival rates of the embryos. The results showed that the embryos had the highest lengths, Fv/Fm values and survival percentages when cultured under a temperature of 20℃ and 25% sunlight intensity. The full level of solar radiation severely reduced the growth and survival ratios of the embryos. Hizikia embryos recovered within 2 h from the damage caused by short-term（30 min） high radiation（about 70% of full solar radiation） and UVR exposure. However, the viabilities of the embryos were significantly decreased after 4 h exposure to UVR. According to these results, we propose that culture conditions with indoor natural light and room temperature would be favorable for the growth, development and physiology of H izikia embryos.展开更多
Since the calibration accuracy decreases with the reduction of irradiance power,the nonlinearity of sensitivity is experimentally investigated and corrected in order to improve the precision of calibration for Solar I...Since the calibration accuracy decreases with the reduction of irradiance power,the nonlinearity of sensitivity is experimentally investigated and corrected in order to improve the precision of calibration for Solar Irradiance Absolute Radiometer( SIAR). The optimization method is proposed based on the interpolation approximation principle. The real-time correction sensitivities are repeatedly measured at each radiant power.The relative system error of sensitivity nonlinearity is 2.2%. The impact of sensitivity nonlinearity is analyzed.The radiant powers are measured by the optimization method and the traditional method. The comparison experiment results illustrate that the optimization method improves the measure accuracy to 0. 1%. The sensitivity nonlinearity is compensated by the real-time correction. Thus,the optimization method significantly improves the calibration precision of ground-based comparison experiment. The investigation of sensitivity nonlinearity also provides the theoretical and experimental basis for optimizing the on-orbit calibration precision of Total Solar Irradiance Monitor( TSIM).展开更多
There have emerged ample literature about the Second Law analysis of extraterrestrial and terrestrial solar radiation consequent to the pioneer works by R. Petela and D. C. Spanner, of which most are irrelevant to the...There have emerged ample literature about the Second Law analysis of extraterrestrial and terrestrial solar radiation consequent to the pioneer works by R. Petela and D. C. Spanner, of which most are irrelevant to the frequency distribution of solar radiation. Since the Second Law analysis was introduced to the fields like photovoltaic and photosynthesis, rendering a need for a method closely related to solar radiation spectrum, some authors created wavelength dependent dilute factots to take the various influence of atmosphere on the frequency distribution into consideration. Because of the complexity of the influence on different frequency, it is not convenient and accurate enough to practically apply the present exergy theories of diluted solar radiation to real solar exergy systems at the surface of the earth. This paper shows a numerical method of Second Law analysis in dealing with the cases of diluted solar irradiance on the earth, based on the observed spectra of global direct and diffuse展开更多
文摘Maintaining a steady power supply requires accurate forecasting of solar irradiance,since clean energy resources do not provide steady power.The existing forecasting studies have examined the limited effects of weather conditions on solar radiation such as temperature and precipitation utilizing convolutional neural network(CNN),but no comprehensive study has been conducted on concentrations of air pollutants along with weather conditions.This paper proposes a hybrid approach based on deep learning,expanding the feature set by adding new air pollution concentrations,and ranking these features to select and reduce their size to improve efficiency.In order to improve the accuracy of feature selection,a maximum-dependency and minimum-redundancy(mRMR)criterion is applied to the constructed feature space to identify and rank the features.The combination of air pollution data with weather conditions data has enabled the prediction of solar irradiance with a higher accuracy.An evaluation of the proposed approach is conducted in Istanbul over 12 months for 43791 discrete times,with the main purpose of analyzing air data,including particular matter(PM10 and PM25),carbon monoxide(CO),nitric oxide(NOX),nitrogen dioxide(NO_(2)),ozone(O₃),sulfur dioxide(SO_(2))using a CNN,a long short-term memory network(LSTM),and MRMR feature extraction.Compared with the benchmark models with root mean square error(RMSE)results of 76.2,60.3,41.3,32.4,there is a significant improvement with the RMSE result of 5.536.This hybrid model presented here offers high prediction accuracy,a wider feature set,and a novel approach based on air concentrations combined with weather conditions for solar irradiance prediction.
基金Supported by the Marine Special Program of Jiangsu Province in China (No.JSZRHYKJ202007)the National Natural Science Foundation of China (No.40801145)。
文摘Accurate measurements of upwelling irradiance just beneath the ocean surface,E_(u)(λ,0^(-)),can be used to calculate ocean optical parameters,and further develop retrieval algorithms for remotely sensing water component concentrations.Due to the effects of sea surface waves,perturbation from instrument platform(ship),and instrument self-shading,E_(u)(λ,0^(-))is often difficult to be accurately measured.This study presents a procedure for extrapolating the E_(u)(λ,0^(-))from the in-water radiometric profile measurements.Using the optical profile data from 13 bands(ranging from 381 to 779 nm)measured by 45 casts in the Ligurian Sea during 2003–2009,the E_(u)(λ,0^(-))was extrapolated from in-water upwelling irradiance measurements between the initial shallow depth,Z_(0),and an optimal bottom depth,Z_(1),by three linear models(linear,2-degree polynomial,and exponential)and two nonlinear models(LOESS and spline).The accumulated errors of extrapolated E_(u)(λ,0^(-))at each wavelength for the five models were calculated.It was found that the optimal Z_(1) depth for the linear and exponential models was at the depth of80%of E_(u)(λ,Z_(0)),50%of E_(u)(λ,Z_(0))for the 2-degree polynomial model,40%of E_(u)(λ,Z_(0))for the LOESS model,and 15%of E_(u)(λ,Z_(0))for the spline model.The extrapolated E_(u)(λ,0^(-))derived from the five models was in good agreement with the calculated true E_(u)(λ,0^(-)).In all bands,the 2-degree polynomial model achieved the highest accuracy,followed by the LOESS model.In the short band of 381–559 nm,the linear and exponential models had the third-best performance,and the spline model performed worst within this range.For the red band of 619–779 nm,the accuracies of the exponential and spline models had the third highest performance,and the linear model produced lowest accuracy.Hence,the 2-degree polynomial model was an optimal procedure for extrapolation of E_(u)(λ,0^(-))from the in-water radiometric profile measurements.
文摘Increasing global energy consumption has become an urgent problem as natural energy sources such as oil,gas,and uranium are rapidly running out.Research into renewable energy sources such as solar energy is being pursued to counter this.Solar energy is one of the most promising renewable energy sources,as it has the potential to meet the world’s energy needs indefinitely.This study aims to develop and evaluate artificial intelligence(AI)models for predicting hourly global irradiation.The hyperparameters were optimized using the Broyden-FletcherGoldfarb-Shanno(BFGS)quasi-Newton training algorithm and STATISTICA software.Data from two stations in Algeria with different climatic zones were used to develop the model.Various error measurements were used to determine the accuracy of the prediction models,including the correlation coefficient,the mean absolute error,and the root mean square error(RMSE).The optimal support vector machine(SVM)model showed exceptional efficiency during the training phase,with a high correlation coefficient(R=0.99)and a low mean absolute error(MAE=26.5741 Wh/m^(2)),as well as an RMSE of 38.7045 Wh/m^(2) across all phases.Overall,this study highlights the importance of accurate prediction models in the renewable energy,which can contribute to better energy management and planning.
文摘[Objective] The study aimed to prove effects of NO on oxidative damage and photosynthetic apparatus at filling stage of wheat leaves under high temperature and irradiance stress.[Method] Yunong 949 was taken as experimental material to study the effects of sodium nitropprusside (SNP,an exogenous nitric oxide donor) at 0.1 mmol/L on protective enzyme activities, oxidative damage and fluorescence.[Result] The treatment with SNP (at 0.1 mmol/L) significantly increased the activity of SOD and APX, proline content, decreased the MDA content and relative electrical conductivity, Kept the higher Fv/Fm and lower Fo.[Conclusion] The adaptability of wheat with SNP treatment at 0.1 mmol/L was improved under high temperature and irradiance stress.
文摘The focusing tomography is presented to reconstruct 3 dimensional irradiance distribution. A 3 dimensional luminous body could be considered as the combination of many 2 dimensional parallel luminous sections. Focus on these discrete sections respectively by a single camera, a group of images would be captured to form governing equations of irradiance. After inversion procedure, the irradiance distribution of different sections could be decoded. In this experimentation two lightbulbs are used to simulate two luminous sections. Reasonable results demonstrate that this technique could be a useful method in irradiance reconstruction after further development.
基金Supported by the National Natural Science Foundation of China(NSFC)(Nos.41576159,U1133003)the National High Technology Research and Development Program of China(863 Program)(No.2013AA065805)
文摘Blooms of Phaeocystis globosa have been frequently reported in Chinese coastal waters, causing serious damage to marine ecosystems. To better understand the ecological characteristics of P. globosa in Chinese coastal waters that facilitate its rapid expansion, the effects of temperature, salinity and irradiance on the growth of P. globosa from the South China Sea were examined in the laboratory. The saturating irradiance for the growth ofP. globosa （Is） was 60 μmol/（m^2·s）, which was lower than those of other harmful algal species （70-114μmol/（m^2·s））. A moderate growth rate of 0.22/d was observed at 2 μmol/（m^2·s） （the minimum irradiance in the experiment）, and photo-inhibition did not occur at 230 μmol/（m^2·s） （the maximum irradiance in the experiment）. Exposed to 42 different combinations of temperatures （10- 31 ℃） and salinities （10-40） under saturating irradiance, P. globosa exhibited its maximum specific growth rate of 0.80/d at the combinations of 24℃ and 35, and 27℃ and 40. The optimum growth rates （〉0.80/d） were observed at temperatures ranging from 24 to 27℃ and salinities from 35 to 40. While P. globosa was able to grow well at temperatures from 20℃ to 31℃ and salinities from 20 to 40, it could not grow at temperatures lower than 15℃ or salinities lower than 15. Factorial analysis revealed that temperature and salinity has similar influences on the growth of this species. This strain ofP. globosa not only prefers higher temperatures and higher salinity, but also possesses a flexible nutrient competing strategy, adapted to lower irradiance. Therefore, the P. globosa population from South China Sea should belong to a new ecotype. There is also a potentially high risk of blooms developing in this area throughout the year.
文摘factor experiment was used to study the combined effects of temperature, irradiance and salinity on the growth of an HAB species diatom Skeletonema costatum (Grev.) Cleve. The results showed that temperature (12, 19, 25, 32℃), irradiance ((0.02, 0.08, 0.3, 1.6)×10 16 quanta/(s·cm 2)) and salinity (10, 18, 25, 30, 35) significantly influenced the growth of this species. There were interactive effects between any two of and among all three physical factors on the growth. In the experiment, the most optimal growth condition for S. costatum was temparature of 25℃, salinity of 18-35 and irradiance of 1.6×10 16 quanta/(s·cm 2). The results indicated S. costatum could divide at higher rate and were more likely to bloom under high temperature and high illumination from spring to fall. It was able to distribute widely in ocean and estuary due to its adaptation to a wide range of salinities.
基金Supported by the Shandong Agriculture Seedstocks Project and the Knowledge Innovation Program of the Chinese Academy of Sciences (No. KSCX2-YW-N-47-02)the National High Techmology Research and Development Program of China (863 Program) (No.2006AA09Z421)and Experimental Marine Biology Lab, IOCAS
文摘Chondrus is a type of commercially produced red seaweed that widely used for food and carrageen extraction. Although the natural life history of the alga had been well understood, the factors influencing development of the tetraspore and carpospore remain poorly understood. In the perspective of seedling resources, the regulation of early development is crucial for the seedlillg nursing; therefore, it is necessary to understand the physiological influences during its early development. In this study, we studied the effects of temperature and irradiance on the early development of Chondrus ocellatus Holm under laboratory conditions. The released tetraspores and carpospores were cultivated at different temperatures （10-28℃） and irradiances （10, 60 μmol photons m^-2s^-1） with a photoperiod of 12L： 12D. The results indicate that both tetraspores and carpospores are tolerant to temperatures of 10-25℃, and have the highest relative growth rate at 20℃. Irradiance variances influenced the growth of the discoid crusts, and the influence was more significant with increasing temperature; 60 μmol photons m^-2s^-1 was more suitable than 10 μmol photons m^-2s^-1. The optimum temperature and irradiance for the development of seedlings was 20℃ and 60 μmol photons m^-2s^-1, respectively.
基金supported by the National Key Research and Development Program of China (No.2016YFB0501405)the National Natural Science Foundation of China (No.11973073)+1 种基金the Basic Project of Ministry of Science and Technology of China (No.2015FY310200)the Shanghai Key Laboratory of Space Navigation and Position Techniques (No.06DZ22101)
文摘Solar radiation pressure is the main driving force and error source for precision orbit determination of navigation satellites.It is proportional to the solar irradiance,which is the"sun constant".In regular calculation,the"solar constant"is regard as a constant.However,due to the existence of sunspots,flares,etc.,the solar constant is not fixed,the change in the year is about 1%.To investigate the variation of solar irradiance,we use interpolation and average segment modeling of total solar irradiance data of SORCE,establishing variance solar radiation pressure(VARSRP)model and average solar radiation pressure(AVESRP)model based on the built solar pressure model(SRPM)(constant model).According to observation data of global positioning system(GPS)and Beidou system(BDS)in 2015 and comparing the solar pressure acceleration of VARSRP,AVESRP and SRPM,the magnitude of change can reach 10-10 m/s^2.In addition,according to the satellite precise orbit determination,for GPS satellites,the results of VARSRP and AVESRP are slightly smaller than those of the SRPM model,and the improvement is between 0.1 to 0.5 mm.For geosynchronous orbit(GEO)satellites of BDS,The AVESRP and VARSRP have an improvement of 3.5 mm and 4.0 mm,respectively,based on overlapping arc,and SLR check results show the AVESRP model and the VARSRP model is improved by 2.3 mm and 3.5 mm,respectively.Moreover,the change of inclined geosynchronous orbit(IGSO)satellites and medium earth orbit(MEO)satellites is relatively small,and the improvement is smaller than 0.5 mm.
基金We are grateful for financial supports from National Key Research and Development Program(Grant No.2017YFA0701200)National Science Foundation of China(No.11704030).The author Z X Feng thanks the valuable discussions with Xu-Jia Wang and Rengmao Wu.
文摘Current freeform illumination optical designs are mostly focused on producing prescribed irradiance distributions on planar targets.Here,we aim to design freeform optics that could generate a desired illumination on a curved target from a point source,which is still a challenge.We reduce the difficulties that arise from the curved target by involving its varying z-coordinates in the iterative wavefront tailoring(IWT)procedure.The new IWT-based method is developed under the stereographic coordinate system with a special mesh transformation of the source domain,which is suitable for light sources with light emissions in semi space such as LED sources.The first example demonstrates that a rectangular flat-top illumination can be generated on an undulating surface by a spherical-freeform lens for a Lambertian source.The second example shows that our method is also applicable for producing a non-uniform irradiance distribution in a circular region of the undulating surface.
基金supported by the B-type Strategic Priority Program No.XDB41000000funded by the Chinese Academy of Sciences and the pre-research project on Civil Aerospace Technologies No.D020105funded by China's National Space Administration(CNSA).The authors also acknowledge support from the National Natural Science Foundation of China(NSFC)through grants 41904154,41525015,and 41774186.
文摘An important population of the dayside Martian ionosphere are photoelectrons that are produced by solar Extreme Ultraviolet and X-ray ionization of atmospheric neutrals.A typical photoelectron energy spectrum is characterized by a distinctive peak near 27 eV related to the strong solar HeⅡ emission line at 30.4 nm,and an additional peak near 500 eV related to O Auger ionization.In this study,the extensive measurements made by the Solar Wind Electron Analyzer on board the recent Mars Atmosphere and Volatile Evolution spacecraft are analyzed and found to verify the scenario that Martian ionosphere photoelectrons are driven by solar radiation.We report that the photoelectron intensities at the centers of both peaks increase steadily with increasing solar ionizing flux below 90 nm and that the observed solar cycle variation is substantially more prominent near the O Auger peak than near the HeⅡ peak.The latter observation is clearly driven by a larger variability in solar irradiance at shorter wavelengths.When the solar ionizing flux increases from 1 mW·m^-2 to 2.5 mW·m^-2,the photoelectron intensity increases by a factor of 3.2 at the HeⅡ peak and by a much larger factor of 10.5 at the O Auger peak,both within the optically thin regions of the Martian atmosphere.
基金This work was supported by the Key Research and Development Program of Shaanxi(2018ZDXM-GY-091)the National Key Research and Development Project of China(2018YFB1309403)+2 种基金the Natural National Science Foundation of China(61805199)Natural Science Basic Research Plan in Shaanxi Province of China(2018JQ6065)We would like to sincerely thank all reviewers for their helpful comments and suggestions.
文摘Currently,polarization visualization strategies are accomplished by mapping polarization information into a perceptually uniform color appearance model CAM02-UCS.However,the deviation of the CAM02-UCS space from the lightness prediction results in an inaccurate match between the polarization information and the perceptual information.In this paper,we propose a novel polarization visualization strategy based on the perceptual uniform space Jzazbz.The polarization visualization be completed by placing the polarization information into the lightness Jz,colorfulness Cz and hue angle hz channels of the Jzazbz space.The experimental results show that the proposed method can significantly improve the lightness of the low irradiance and high polarization region,hence more polarization information can be sensed by human visual system.
基金supported by the National Key R&D Program of China grant number 2017YFA0603504the Strategic Priority Research Program of the Chinese Academy of Sciences grant number XDA17010101the National Natural Science Foundation of Chinagrant number 41875183。
文摘Surface irradiance measurements with high temporal resolution can be used to detect clear skies,which is a critical step for further study,such as aerosol and cloud radiative effects.Twenty-one clear-sky detection(CSD)methods are assessed based on five years of 1-min surface irradiance data at Xianghe—a heavily polluted station on the North China Plain.Total-sky imager(TSI)discrimination results corrected by manual checks are used as the benchmark for the evaluation.The performance heavily relies on the criteria adopted by the CSD methods.Those with higher cloudy-sky detection accuracy rates produce lower clear-sky accuracy rates,and vice versa.A general tendency in common among all CSD methods is the detection accuracy deteriorates when aerosol loading increases.Nearly all criteria adopted in CSD methods are too strict to detect clear skies under polluted conditions,which is more severe if clear-sky irradiance is not properly estimated.The mean true positive rate(CSD method correctly detects clear sky)decreases from 45%for aerosol optical depth(AOD)≤0.2%to 6%for AOD>0.5.The results clearly indicate that CSD methods in a highly polluted region still need further improvements.
基金by the National Natural Science Foundation of China(No.51704301)National Defense Technology Project Foundation(No.3604031)Youth Scientific Research Foundation of LEU(No.YQ16-420802),are gratefully acknowledged.
文摘In order to investigate the burning characteristics of a 0#diesel and 3#jet fuel,a small-scale experimental bench mainly composed of a cone calorimeter was arranged.The heat release and burning rates were investigated changing the external irradiance in order to clarify the triadic relationship among these quantities.The effective heat of combustion of 0#diesel and 3#jet fuel were 38.89 MJ/kg and 43.15 MJ/kg,respectively,with the corresponding combustion efficiencies being 96.78%and 99.60%(the effective peak heat of combustion being 1.665 times the mean value for both types of fuel).According to our experimental results,the heat release rate and burning rate of 0#diesel and 3#jet fuel both grow linearly with an increase in the external irradiance.Moreover,the heat release rate and burning rate of 3#jet fuel are greater than the equivalent values for the 0#diesel.The average smoke production rate of 0#diesel grows with an increase in the external irradiance,while for the 3#jet fuel it remains approximately the same.The specific extinction area of these two kinds of fuel shows a subtle decrease with the increase of external irradiance.The time to ignition of 3#jet fuel is smaller than 0#diesel for all the considered external irradiances,which indicates that 3#jet fuel is easier to ignite than the 0#diesel.
文摘The solar UV radiation has prominent impacts on human life, animals and plants with positive and negative effects. Atmospheric ozone, which is formed from the photodissociation of molecular oxygen mainly in the stratosphere, absorbs a significant factor of solar UV radiation. The ozone in the stratosphere acts as a protective layer to prevent UV radiation reaching on the surface of the earth. Hence the intensity of solar UV radiation on the surface has a strong dependence on the Total Ozone Column (TOC). The UV irradiance on earth surface depends on geometrical factors such as solar zenith angle, altitude, latitude and other atmospheric parameters as well. This is an attempt to study the variation of solar UV flux at its four discrete wavelengths ranging from 305 - 380 nm at Kannur, which is located in the north of Kerala in India. Hence such a correlation of TOC and UV irradiance is relevant to realize the radiation budget at this location (12.3N, 75.4E) using AURA OMI data. This paper reveals the correlation of day to day, month to month temporal variation of total ozone column (in DU) and UV irradiance (w/m2). From the analysis, the anti-correlation between UV and TOC is revealed and its impact in the solar radiation budget is established.
文摘The light is one of the important factors for the microalgae growth in the biofuel technology. As biofuel project is large and expensive thus before setting a microalgae based biofuel project in any geographical location, it is important to investigate the suitability of all important parameters involving with the system. This paper aims to investigate the sunlight availability and the microalgae growth for a photobioreactor at Chittagong University of Engineering and Technology (CUET). A computational growth model related to the average irradiance is proposed to calculate the growth of microalgae. We observed that average irradiance is the highest in June and is the lowest in December. From our simulation it is found that the growth of microalgae varies with the average irradiance in a year.
基金Supported by the National High Technology Research and Development Program of China (863 Program) (Nos. 2006AA10A412 2006AA10A416)+1 种基金Main Program of National Science Infrastructure Platform, a project from the Ministry of Science and Technology of China (No. 2006DKA30470-017)a non-profit program from the Ministry of Agriculture of China (No. 200903030)
文摘In our trials, from 2007 to 2008, of mass production of seedlings of Hizikiafusiformis using synchronization techniques, problems of a ＂dark thalli＂ phenomenon and epiphytes contamination severely threatened the health of juvenile seedlings. In this investigation, we optimized conditions for improving the growth of juvenile seedlings. Seven string collectors were seeded with zygotes and a series of experiments were conducted including direct exposure to solar irradiance, co-culture with Ulva spp. and treatment with sodium hypochlorite. It was found that direct exposure to solar irradiance （maximum： 1 740 μmol photons/（m2.s）） for 2 h per day could efficiently enhance the growth of young seedlings and simultaneously inhibit the growth of epiphytic algae. In this treatment, 50-day old seedlings could reach an average of 0.44 cm in length and possess up to nine leaflets. However, a single treatment with 18-mmol/L sodium hypochlorite for 10 rain severely harmed 15-day old seedlings. In comparison, weekly treatment with 2.2-mmol/L sodium hypochlorite for 10 rain brought no apparent harm to seedlings and eliminated epiphytic algae efficiently. However, this treatment significantly increased the detachment rate of seedlings, Inoculating Ulva spp. onto the collector caused a dramatic decrease in the number of seedlings. However, the growth of the remaining seedlings appeared unhampered. All collectors except the control were daily sprayed with a high pressure water jet from the 84 day post fertilization. From the first day to 50th day, no ＂dark thallus＂ was observed on any of the seven collectors. We believe that well-timed daily exposure to solar irradiance would favor H. fusiformis in its early growing stages.
基金Supported by the Science and Technology Planning Project of Guangdong,China(No.2016A020222001)
文摘Understanding the embryo physiology of Hizikia fusiformis（Harvey） Okamura will promote the development of artificial seedlings. In this study, H. fusiformis embryos were cultured under different environmental conditions, including different temperatures（15℃, 20℃, and 25℃）, sunlight intensities（100%, 50%, and 25% of full solar radiation） and types of UVR（UV-A and UV-B）. Then, we determined the lengths, maximal quantum yields（ Fv/Fm）, and survival rates of the embryos. The results showed that the embryos had the highest lengths, Fv/Fm values and survival percentages when cultured under a temperature of 20℃ and 25% sunlight intensity. The full level of solar radiation severely reduced the growth and survival ratios of the embryos. Hizikia embryos recovered within 2 h from the damage caused by short-term（30 min） high radiation（about 70% of full solar radiation） and UVR exposure. However, the viabilities of the embryos were significantly decreased after 4 h exposure to UVR. According to these results, we propose that culture conditions with indoor natural light and room temperature would be favorable for the growth, development and physiology of H izikia embryos.
基金Sponsored by the National Natural Science Foundation of China(Grant Nos.41227003 and 41474161)
文摘Since the calibration accuracy decreases with the reduction of irradiance power,the nonlinearity of sensitivity is experimentally investigated and corrected in order to improve the precision of calibration for Solar Irradiance Absolute Radiometer( SIAR). The optimization method is proposed based on the interpolation approximation principle. The real-time correction sensitivities are repeatedly measured at each radiant power.The relative system error of sensitivity nonlinearity is 2.2%. The impact of sensitivity nonlinearity is analyzed.The radiant powers are measured by the optimization method and the traditional method. The comparison experiment results illustrate that the optimization method improves the measure accuracy to 0. 1%. The sensitivity nonlinearity is compensated by the real-time correction. Thus,the optimization method significantly improves the calibration precision of ground-based comparison experiment. The investigation of sensitivity nonlinearity also provides the theoretical and experimental basis for optimizing the on-orbit calibration precision of Total Solar Irradiance Monitor( TSIM).
文摘There have emerged ample literature about the Second Law analysis of extraterrestrial and terrestrial solar radiation consequent to the pioneer works by R. Petela and D. C. Spanner, of which most are irrelevant to the frequency distribution of solar radiation. Since the Second Law analysis was introduced to the fields like photovoltaic and photosynthesis, rendering a need for a method closely related to solar radiation spectrum, some authors created wavelength dependent dilute factots to take the various influence of atmosphere on the frequency distribution into consideration. Because of the complexity of the influence on different frequency, it is not convenient and accurate enough to practically apply the present exergy theories of diluted solar radiation to real solar exergy systems at the surface of the earth. This paper shows a numerical method of Second Law analysis in dealing with the cases of diluted solar irradiance on the earth, based on the observed spectra of global direct and diffuse
