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To effectively eliminate optical end loss for small-scale linear solar concentrators, a fixed linear-focus Fresnel lens solar system (FLFS) with triangle cavity receiver is described and the principle is provided. The effects of the receiver parameters including receiver position f, solar declination angle δ , solar hour angle ω , internal surface absorptivity α a b and end plane reflectivity ρ r on the end loss ratio ( μ o e l ) and relative optical efficiency ( η r e − o p t ) of the proposed system have been studied by the control variable method and Monte Carlo ray tracing (MCRT) method which is implemented by software TracePro®. Significance tests of critical factors are conducted to assess the effect of receiver parameters. These results revealed that the FLFS could effectively solve the problem of optical end loss of linear solar concentrators. When f = 650 mm and δ = 0°, 8°, 16°, and 23°27 ′ , the corresponding average η r e − o p t at ω from 0° to 60° are 0.9459, 0.9422, 0.9145, and 0.8144, respectively. As δ increases, reducing f can ensure the system operates at a high-efficiency state. The η r e − o p t shows a positive relationship with α a b and no relationship with ρ r . δ occupies the greatest significant influence on η r e − o p t , which is followed by ω , α a b and f.

The method for precisely determining the astronomical azimuth using the local hour angle (LHA) of Polaris is only applicable in northern middle latitudes. In addition, the meridian star pair method is limited by the conditions of star selection and matching. A new hour angle method for multiple meridian stars is proposed, which is suitable for any part of the global region. When multiple south and north stars have been observed, the influence of longitude error and timing error on the azimuth is modified by linear regression. A precise astronomical position is not required, and there is no limit to the specific position of the meridian stars. Therefore, both the number of observable stars and work efficiency are greatly increased. Our experiment indicates that the results of the new method can reach the first-order accuracy level; i.e., the root mean square error (RMSE) is less than 0.5 ″ , even when the amount of observed data is reduced to half that of the Polaris method.

In this study, performance analysis of flat plate solar collector has been carried out analytically. A comprehensive mathematical modelling of thermal performance is modelled using Response Surface Methodology and optimal geometrical and thermodynamic parameters are predicted pertaining to optimum performance of the system. In this study a model was developed for evaluating and predicting the efficiency, outlet temperature and performance of a flat plate solar collector considering the hour angle, day and input temperature as input parameters. In the cause of the work it was found that the days and months close to the beginning of the year (January, February, March and April) yielded higher outlet temperature and solar radiation due to dry season, while the months at the middle of the year showed lower outlet temperature and solar radiation due to the rainy season. The months towards the ending of the year also showed higher outlet temperature and solar radiation respectively.

The most integral aspect of optimizing solar energy applications is the assessment of solar radiation. Devises of solar energy will work better if the radiation that is to be obtained is measured long before. Solar radiation measurement models are created because of the unavailability of solar radiation measuring instruments at the station of interest. In this paper, four (4) artificial neural network models are developed for assessing daily solar radiation. Solar radiation data for training and testing the ANN models are collected from Reggane city, in the south of Algeria. Input data based on meteorological and astronomical parameters such as: relative humidity, declination, average air temperature, hour angle and extraterrestrial solar irradiation. Those ANN-based models study uses the Levenberg–Marquardt algorithm and collected during six years. The efficiency of models was assessed using statistical tests, including mean bias error, root mean squared error, mean absolute error and correlation coefficient. The statistical analysis of the results showed that, relative to other models, Model 4 provided the best combination of global solar radiation for estimating, with coefficient of correlation (R) higher than 0.91, the mean absolute error does not exceed 7% and relative RMSE does not exceed 10%. This model can be used when data is available for heating, cooling and designing solar energy systems in Sahara climatic regions.

In order to further improve the efficiency of daylight harvesting system, a high accuracy solar tracking system is required. The tracking error is the combined result of various sources, such as the azimuth rotational axis tilt, geo-positioning deviation, installation deviation, true north meridian deviation, calculation error and mismatch of photo sensors, etc. In this paper, we designed a dual-axis hybrid tracking system which uses GPS/BeiDou for geological location, photodiodes for closed loop tracking, and orientation algorithm for open loop tracking. The difference of our calculated the solar hour angle, altitude angle and azimuth angle to that of SOLPOS results are less than 1°. An initializing calibration is proposed to correct the errors caused by the mismatch of photodiodes. The installation deviation, geo-positioning error and true north meridian deviation for orientation algorithm are also analyzed and corrected. This field test shows that the overall tracking accuracy of the system is improved after the second dynamic compensation. The tracking system can be used in a low cost and small form factor solar tracker with easy setup by providing geological location, orientation sensing and auto corrections for weight and wind load if the photo sensors are positioned at the deflection location.

International audience; The Dark Energy Spectroscopic Instrument (DESI) is a Stage IV ground-based dark energy experiment that will measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 35 million galaxies and quasars over 14000 square degrees will be measured during the life of the experiment. We describe the installation of the major elements of the instrument at the Mayall 4m telescope, completed in late 2019. The previous prime focus corrector, spider vanes, and upper rings were removed from the Mayall’s Serrurier truss and replaced with the newlyconstructed DESI ring, vanes, cage, hexapod, and optical corrector. The new corrector was optically aligned with the primary mirror using a laser tracker system. The DESI focal plane system was integrated to the corrector, with each of its ten 500-fiber-positioner petal segments installed using custom installation hardware and the laser tracker. Ten DESI spectrographs with 30 cryostats were installed in a newly assembled clean room in the Large Coude Room. The ten cables carrying 5000 optical fibers from the positioners in the focal plane were routed down the telescope through cable wraps at the declination and hour angle axes, and their integral slitheads were integrated with the ten spectrographs. The fiber view camera assembly was installed to the Mayall’s primary mirror cell. Servers for the instrument control system replaced existing computer equipment. The fully integrated instrument has been commissioned and is ready to start its operations phase.

Extraterrestrial solar irradiance (KEX) is the solar irradiance at the “top” of the Earth’s atmosphere, on a plane perpendicular to the Sun’s rays, and at mean Earth–Sun distance. To calculate the amount of irradiance available in the photic zone, the maximum possible extraterrestrial irradiance or the solar constant, which is 1366 + 3 Watts per square meter (or W m−2), is adjusted downward to account for atmospheric attenuation and finally attenuation rates in the water body, as a function of the reciprocal of the inverse square law—the radius vector—the Earth–Sun distance d divided by the mean of d throughout the year, along with the zenith angle (z) formed by the Sun, the surface point of interest, and the vertical. The zenith angle can be computed as a function of the latitude of interest, the latitude experiencing the direct rays of the Sun on that day, i.e., solar declination (δ), and the angle that the Earth has yet to rotate through to reach solar noon or hour angle (h). On a clear day, perhaps 80% of KEX will be transmitted to the surface. However, under heavy clouds, as little as 10% of KEX reaches the surface. When solar radiation strikes a water surface at any angle other than the vertical, refraction occurs because of the density difference between air and water. In oceanography and coastal sciences, modeling the radiation emitted by a point or area source of light (usually the Sun) can often be important. Three-dimensional radiant intensity can be used to derive the amount of energy radiated by and onto points or bodies in the ocean.

In solar engineering, many simulations require the computation of averages over a year of quantities such as the efficiency of solar plants. In the case of stationary quantities, i.e., that do not depend on the past history but only on the present conditions, time averages can be replaced by averages over the solar position, which are much faster to compute. Through a suitable choice of coordinates for the Sun position, namely, the hour angle and a declination-equivalent coordinate, the problem can be rewritten as a comparatively simple expression involving the sum of two double integrals; the solution can then be obtained numerically via suitable fast quadrature methods. The average over a year can be computed by transforming the dependence on irradiation, cloudiness, temperature or other instantaneous parameters into two dependences on Sun position – one for winter-spring (ascending declination) and one for summer-winter (descending declination). The proposed method is substantially faster than usual time integration over a year: the speedup factor ranges from 18 to almost 700 in the considered examples. It is especially well-suited to computations that require many yearly averages and could even be unfeasible otherwise. Examples of such applications include multi-parameter optimisations of the configuration of a power plant with the goal of maximizing the overall year production.

This paper evaluates the optimum tilt angle and available direct solar radiation on the inclined surface of the PV Cell in the province Punjab, Pakistan. This mathematical model provides the maximization of Solar Radiation impinging on the Solar collectors. Instead of Solar Collector placed at latitude angle with the help of parameters like Slope, orientation, azimuth surface angle and the hour angle of the PV Cell. The variation in the Solar Radiation on the PV Cell from Latitude to Tilt angle is represented graphically. Considered cities of Punjab are Lahore, Mangla, Sialkot, Gujranwala and Multan. This study reveals that as latitude angle varies from 33° to 28°, intensity increases approximately from 0.3KWh/m2 to 0.6KWh/m2 which will result in increased output power. Seasonal optimum angle has also been listed. Optimization of tilt angle has the highest effect on solar irradiance in winter season when day is shorter hence more light is required to fulfill our requirement.

Precise determination of the astronomical azimuth using the local hour angle (LHA) of Polaris is only applicable in northern middle latitudes. Therefore, to achieve fast and precise astrono...

Sun-shadow positioning technology is a new positioning method, namely, by providing the changes in objects’ sun-shadow, to determine the location and date of shooting in communication networks. Based on the analysis of changes about the sun-shadow. This paper, by using the solar azimuth, elevation, declination angle, and solar hour angle, has established the mathematical model to determine the position and date of some objects. Firstly, the principle of the sun-shadow is analyzed by using the relevant parameters, sun-shadow and geographical coordinates and the provided moments. Secondly, it has used two different methods to calculate the positions. At last, it gets 40 groups of information about the length of straight shadow every one minute from 8:55 by using CAD software for video information processing. Then, it has soluted the actual length of shadow making use of a similar relationship. According to the relationship between the camera coordinate system and the world coordinate system, consulting the solution of the latitude and the longitude under the sundial model, we find the places in the video maybe in Hohhot during July.

The current paper revolves around a MATLAB project for calculation of solar incidence angle, solar altitude angle and solar azimuth angle of any specific point on earth at any time of day for any date. This model helps us to know the optimum position of the solar panel for the maximum power generation from sun at any point of time for specific location. This model also helps us in comparing the difference in the given angles at any day or time of year.

In this study, the exact amount of the rate of irradiance within the ambit of a tube in the evacuated tube solar collector (ETSC) has been measured in various hours of the day by means of a solar meter. Some novel correlations for determining the distribution of insolation intensity around the tube have been proposed by the analysis of experimental data. A correlation is offered by using the results of previous studies and mathematical analysis. The offered correlation is utilized to calculate the direction and the amount of the maximized insolation intensity in cross section area of the tube concerning geographical circumstances, hour angle, and the slope of the collector by denoting the solar radiation distribution function around the section of the tube. Moreover, by integrating around the tube, a correlation for calculation of the whole amount of the absorbed radiation through the absorber has been presented. In the end, the error analysis is conducted and the maximum amount of error for the proposed model is estimated to be 8% before 5 p.m., and at solar noon the amount of error is reported less than 1%. Furthermore, the energy efficiency of the constructed water heater is obtained as 65%.

The Ultraviolet Forward Spectrometer is a new type of spectrometer for monitoring the vertical distribution of atmospheric trace gases in the global middle atmosphere. It is on the TianGong-2 space laboratory, which was launched on 15 September 2016. The spectrometer uses a solar calibration mode to modify its irradiance. Accurately calculating the solar orientation is a prerequisite of spectral calibration for the Ultraviolet Forward Spectrometer. In this paper, a method of calculating the solar orientation is proposed according to the imaging geometric characteristics of the spectrometer. Firstly, the solar orientation in the horizontal rectangular coordinate system is calculated based on the solar declination angle algorithm proposed by Bourges and the solar hour angle algorithm proposed by Lamm. Then, the solar orientation in the sensor coordinate system is achieved through several coordinate system transforms. Finally, we calculate the solar orientation in the sensor coordinate system and evaluate its calculation accuracy using actual orbital data of TianGong-2. The results show that the accuracy is close to the simulation method with STK (Satellite Tool Kit), and the error is not more than 2 %. The algorithm we present does not need a lot of astronomical knowledge, but only needs some observation parameters provided by TianGong-2.

This paper proposes a mobile sun-tracking system, which allows continuous tracking of the sun and effective harvesting of solar energy on mobile platforms. Based on the dynamic sun-tracking algorithm which we previously proposed, the system takes not only the date, time, and geographical information, but also the dynamic changes of coordinates of the mobile platforms into account to calculate the hour angle of sun relative to the ideal azimuth elevation axes in real time. The advantage of this design is that it can be easily duplicated for mass deployment on the land or ocean. Our results show that the accuracy of mobile tracking in stationary state is 8.085 mrad while the accuracy in mobile state is 127 mrad on average.

The brightness temperature (TB) data of the Moon acquired by the microwave radiometer (MRM) on-board the Chinese Chang’e-2 (CE-2) lunar probe are valuable and comprehensive data, which can be helpful in studying the physical properties of the lunar regolith, such as thickness, physical temperature, and dielectric constant. To construct the accurate and high-resolution lunar TB model with the TB data obtained by the MRM on-board CE-2, 2401 tracks of the original TB data are quantized by using the hour angle processing, and the hierarchical MK splines function (HMKSF) method is presented, which uses a hierarchy of coarse-to-fine control lattices to generate a sequence of TB model functions. The TB model constructor is the sum of the TB model functions derived at each level of the hierarchy. In addition, the lunar TB models with a resolution of $0.5 {^{\circ }} \times 0.5 {^{\circ }}$ in all four frequency channels are constructed for both the daytime and the nighttime. The obtained models show rich information, e.g., the global distribution of TB over the lunar surface, the effect of frequency on the TB model.

The purpose of this work is to develop a simple control law to implement stable orbits about a small rotating celestial body to achieve global coverage as well as fixed-body hovering on the equatorial plane. The celestial body is assumed to be rotating about a principal axis, with constant rotational velocity along the largest moment of inertia. A simple three dimensional closed-loop guidance law function of position and velocity is defined and analyzed, enabling the determination of the guidance constants to assure convergence to any desired circular orbit about the irregular celestial body, controlling independently five orbital parameters: inclination, right ascension of the ascending node, orbital radius, orbital rate and equatorial longitude. Representative numerical results are presented for an Eros type asteroid.

This paper represents a framework for forecasting solar radiation data per hour using mean of solar radiation on daily basis. The proposed model which is used for forecasting is wavelet neural network. Sunset hour angle, hour angle and daily solar radiation are the three inputs of this model. The output layer has one node which is mean hourly solar radiation (HSR). The proposed model has been trained and developed using MATLAB software. The outcomes achieved here have better prediction precision in comparison to some previous empirical models. To evaluate the proposed model, two error statistical method such as root mean square error and mean absolute percentage error has been implemented. Finally R2 estimation of 96% of the proposed model demonstrates that it can be implemented easily and can increase the preciseness of estimation.

Firstly I plan to describe briefly growth of the Radio Astronomy group that was established at TIFR, Mumbai, in early 1963. The Ooty Radio Telescope (ORT) was designed and built indigenously and became operational in early 1970. It consists of a 530m long and 30 m wide parabolic cylindrical antenna that is located on a suitable hill with its axis of rotation parallel to that of the Earth, which allows it to be steered mechanically in hour angle for about ten hours. A phased array allows coverage from - 45 to +45 degrees in declination. Using the lunar occultation observations, angular size of over 1000 radio galaxies with arc-second resolution were made by 1976 for the first time in the world. The observations supported the Big Bang model. An Ooty Synthesis Radio Telescope (OSRT) was operational during 1982-1986. Currently, ORT is being used for Inter-planetary Scintillation observations of compact radio galaxies and Quasars for daily measurements of the velocity of the Solar wind. An active programme for observations of Pulsars is also carried out.

Estimation of global solar radiation using existing models becomes necessary in areas where measurements are not carried outdue to lack of technical knowledge, unavailability of measuring instrument and cost of getting such measurements if available.In this study, the possibility of estimating the global solar radiation for a particular location using another location's sunshine duration data is explored due to the closeness in the latitude of the two locations and to what extent is the estimation true. Ibadan's (latitude 7.37750N) sunshine duration data is used as Iwo's (latitude 7.62920N) sunshine duration data and employed in the Angstrom - Prescott's sunshine based model, while retaining the latitude of Iwo in the model, mean sunset/rise hour angle and extraterrestrial radiation. The sunshine duration data for Ibadan (2008 - 2012) was gotten from International Institute of Tropical Agriculture, Ibadan while the measured global solar radiation data for Iwo (2014 - 2015) was measured at Bowen University Iwo, Osun state in Nigeria. The estimated global solar radiation for Iwo is validated with measured global solar radiation at Iwo by carrying out some statistical analysis like mean bias error (-0.03), root mean square error (0.81), mean percentage error (-0.23), Nash-Sutcliffe error (r2) or coefficient of determination (0.88), coefficient of correlation (0.94). The estimated values when validated against the measured values performed excellently well. Hence it is possible to use the available sunshine duration data of another location as the sunshine duration data when estimating the global solar radiation available at the location of interest.

There are references to astronomical instruments in various Indian works, from the Kātyāyana Śulbasūtra dated earlier than 350 BCE, to the later Siddhānta (mathematical astronomy) texts from the fifth century CE onwards. The simplest of these instruments is the gnomon (sanku) which initially was used for fixing the east-west direction and finding the time, and later for finding the latitude of a location, the Sun’s declination on any day, and other astronomical quantities. More advanced instruments would follow. Bhāskara-II (twelfth century) devised a board-instrument called phalakayantra to measure the hour angle of the Sun.

The sun is an extremely powerful energy resource, and the solar energy is an important renewable energy. Solar energy can be used for producing heat and generating electricity. The amount of solar energy incident on earth is enormous, and it is larger than current and predicted energy requirements in the future. In this chapter, the basic concepts and parametrical performance of the sun and its radiation across the space and earth surface including solar irradiance on earth(i.e., diffuse irradiance and direct normal irradiance, the solar constant, extraterrestrial solar spectrum, extraterrestrial solar irradiance, and extraterrestrial solar radiation on a surface), ground-level solar radiation characteristics(atmosphere effects and solar spectrum), solar angles(i.e., the earth–sun angles, hour angle, declination angle, latitude angle, solar altitude, zenith, and azimuth angles), are described. Solar energy global distribution by belt and nation at variable geometrical regions on the globe is also presented.

In this paper, various solar position parameters to estimate the solar position throughout the year at individual hours have been calculated. A stepwise procedure to calculate various solar parameters like declination angle, hour angle, solar elevation, solar azimuth angles, etc. has also been given. A north eastern city of India, Agartala with latitude 23.80 N and longitude 91.50 E has been chosen as the target location. The equation of time has been calculated in this paper which plays a major role in locating the sun’s position. An algorithm has been designed to calculate the solar parameter angles that specify the sun’s position at any location, at any instant of time. The variations of the respective angles that specify the sun’s position are also given graphically for a particular hour throughout the year.

A method of SVM optimized by using the PSO arithmetic is presented to solve nonlinear regression estimation problems in deep space exploration data analysis. This method is used to process the microwave brightness temperature (TB) data acquired by the CE-1 satellite. Firstly, the SVM regression model is established and some parameters of which are optimized by using the PSO arithmetic. Then, by training the TB data with the optimized SVM model, the relationship between the TB from four frequency channels and the lunar hour angle is established. Finally, the distribution maps of TB from four frequency channels on the entire lunar surface in certain short period are obtained. The error analysis indicates that the results of this paper can be used in the further study of lunar regolith depth. Furthermore, the abnormal data among the measured data can be found out and modified by using this method.

We present the results of 15184 astrometric observations of 322 visual binaries carried out in 2007–2014 at Pulkovo observatory. In 2007, the 26-inch refractor (F = 10413 mm, D = 65 cm) was equipped with the CCD camera FLI ProLine 09000 (FOV 12′ × 12′, 3056 × 3056 pixels, 0.238 arcsec pixel−1). Telescope automation and weather monitoring system installation allowed us to increase the number of observations significantly. Visual binary and multiple systems with an angular distance in the interval 1.ʺ1–78.ʺ6 with 7.ʺ3 on average were included in the observing program. The results were studied in detail for systematic errors using calibration star pairs. There was no detected dependence of errors on temperature, pressure, and hour angle. The dependence of the 26-inch refractor’s scale on temperature was taken into account in calculations. The accuracy of measurement of a single CCD image is in the range of 0.ʺ0005 to 0.ʺ289, 0.ʺ021 on average along both coordinates. Mean errors in annual average values of angular distance and position angle are equal to 0.ʺ005 and 0.°04 respectively. The results are available here http://izmccd.puldb.ru/vds.htmand in the Strasbourg Astronomical Data Center (CDS). In the catalog, the separations and position angles per night of observation and annual average as well as errors for all the values and standard deviations of a single observation are presented. We present the results of comparison of 50 pairs of stars with known orbital solutions with ephemerides.

Demircan, Cihan/0000-0003-2094-0473 WOS: 000514838400011 The change of the solar radiation reaching the earth depending on specific conditions brings the execution of system planning meticulously and optimally by solar power researchers to the fore. For the estimation of the solar radiation, the most frequently used model is the Angtrom-Prescott model. In this model, sunshine ratio plays an important role. In the study, it is attempted to enhance the annual and semi-annual models developed for the city of Mugla, Turkey and to congregate the semi-annual models in a single model by using the Artificial Bee Colony (ABC) algorithm. The results obtained have revealed that in the multiple model relying on only the sunshine duration, the statistical error values were not reduced to very low levels. In order to cope with this problem, the multiple model relying on both the sunshine duration and the sunset-sunrise hour angle has been proposed. In this way, the statistical errors are found to be reduced by about 40% using the ABC algorithm and the multiple model. It was seen that the models recommended are superior to all the models especially in summer and spring months when there is plenty of sunshine.

Every people, in every historical period, developed methods to measure Time both at a daily scale and at a yearly scale. Some of them constructed sundials to represent the apparent trajectory of the Sun around the Earth, by using and developing tools from descriptive and projective Geometry, mainly. This subject acquired a great multidisciplinary interest since ancient times, also for Science of Representation applications. This study presents the first results of an ongoing research concerning some aspects related to Time Measurement. The geometric-spatial setting of the Sun-Earth system is described and is structured parametrically via algorithms, following the known conventions shared and endorsed by gnomonic treatises. A three-dimensional model built with a strictly geometrical approach was developed; this allowed to set parameters (e.g., the latitude of the site, the Sun declination angle, the hour angle, the altitude and collocation of the Sun relative to the sky) and relations dynamically, which define the variation of the length of day and night during the year. The 3D model allowed an in-depth study of the properties and peculiar characteristics of some sundials and a new variant of a known one is also proposed. The unreleased geometrical constructions in Monge’s orthogonal projections were elaborated using by GeoGebra and the 3D models and algorithmic definitions were developed using by Grasshopper and Ladybug plug-ins, eventually visualising the results in Rhinoceros.

The landing area of Chang'E-4 is initially selected as the Von Karman crater inside the South Pole-Aitken basin on the lunar farside. The research would outline science opportunities based on the microwave radiometer data by the field theory. The SVD analyses between the brightness temperature fields of 3 GHz and 37 GHz were done with versus time series data which were calculated by hour angle correction in the Von Karman crater. The results showed that the main factors affecting the spatiotemporal distribution of brightness temperature are roughness, but less affected by FTA. According to the spatial and temporal distribution of brightness temperature anomalies, the site A(Fig 8) was selected as the preselected landing area for Chang'e-4., which is located in the dense isoline region of the heterogeneous correlation map.

New approaches for the computation of the sampling points for an annual simulation of a solar tower power plant are presented. The annual sun-path in azimuth and elevation and in ecliptic longitude and the hour angle are considered. Real measured weather data is considered in the computation of these sampling points.

This paper calculates the most optimum angle for solar panel for 365 days of the year individually using geographical location of Dhaka, Bangladesh. Then it calculates total solar irradiation if any angle is kept constant for 365 days. Then it compares the outputs and determines angle for capturing maximum irradiation. Then it verifies the result with another method. The result presents optimum tilt angle for the city of Dhaka.

Daily global solar radiation decomposition models (DGSRD models) are important to solar photovoltaic, solar thermal utilization and building energy assessment. The existing DGSRD models are analyzed with hourly global solar radiation data measured from January 2009 to December 2011 on Jiading Campus, Tongji University. The results show the existing models established in the form of a Gaussian equation are comparatively accurate, followed by models adjusted or modified from the Whillier – Liu & Jordan models, and the Newell model is of the lowest accuracy. Among the existing models, the CPRG model is the most accurate one. Then four new decomposition models of daily global solar radiation (DGSRD model 1 to DGSRD model 4) are established based on consideration of the solar altitude angle, the solar azimuth angle, the solar hour angle, clearness index and temperature. Based on the analysis of correlation coefficient, relative standard error, mean bias error, mean absolute bias error, root mean square error, Nash–Sutcliffe Equation and t-statistic (t-stat), it is demonstrated that new DGSRD models (DGSRD model 1, DGSRD model 2 and DGSRD model 4) are more accurate than those existing ones, in which the DGSRD model 4 is the most accurate one.

Theoretically, the solar tracking system describe as the device to get the optimize amount of sunlight according to sun movement. So, the shading effect issues can be minimized. This paper is presents the finding of photovoltaic (PV) harvesting energy via dual axis tracking system. The operation of two direct current (DC) motors motion was programme using PIC kit SK40C by using the Lab View Programming software. The first motor system delay timer is set at 15° rotation per hour and second motor system delay timers is set to rotate 180° after 12 pm. The field testing was initially set up at Perlis, Malaysia climate. An actual testing was used to collect the daily data. The result shows that, the output voltage with solar tracking system is 12.93% higher than without tracking system in the sunny day condition.

In this section we shall develop some approximations for the most basic aspect of an ephemeris for the Sun and the stars which will enable the navigator to calculate approximations to the required Greenwich Hour Angle (GHA) and Declination δ of the Sun and stars. Those results can be classified as low precision ephemerides for the Sun and stars.

Heat loss from receivers of solar collectors is a major reason for drop in their efficiency. Receiver pipes enclosed in glass tubes with evacuated annulus show considerable reduction in heat losses. However, manufacturing and maintenance costs for such receivers are high. An inexpensive alternative is a similar receiver with non-evacuated annulus. This paper presents a numerical study of heat loss from a non-evacuated receiver typically used in parabolic trough collectors, generating moderate temperatures and designed particularly for process heat applications. In order to come closer to the realistic situation, rather than assuming uniform temperature distribution on it, receiver pipe temperature has been assumed to be varying along the surface. Sinusoidal and square wave functions are employed in modeling, since actual temperature distributions on solar receiver pipes are combinations of these two functions. Main goal of the paper is to optimize the design of the non-evacuated solar receiver for minimum heat loss, by using CFD technique. Also effects on heat loss from receivers due to different parameters like average temperature (Ta) of the pipe, non-uniformity in the temperature (α) along its surface, hour angle (γ), denoting position of the sun in the sky and radius ratio (RR) of radius of receiver pipe to that of outer glass tube have been studied. It is seen that as non-uniformity in temperature distribution increases in both types of temperature distribution, heat losses from receiver pipes decrease up to 10%. Also as hour angle increases from 0° to 90°, heat loss decreases by 20% in case of sinusoidal temperature distribution and 24% in case of square wave temperature distribution. The effect of radius ratio (RR) on heat loss has been studied. In present study, we found out that 1.375 is critical radius ratio for which heat losses from receiver are minimum

Solar plate collectors are utilized to heat up water or a mixture of water and glycol by capturing solar radiation and transfer this heat to the collector fluid. In this study, the efficiency of solar plate collector during 19th, 20th and 21st of February, was investigated experimentally. The time of day, plate collector mean temperature, solar intensity and external air temperature can effect on the efficiency of solar collector. And the effect of incidence angle on solar irradiation has been studied; as a result, the solar irradiance will be decreased as the angle of incidence increased. A method presented can be used to calculate hour angle, diffuse solar radiation and total solar radiation at various temperatures in this paper its MATLAB programs.

This paper mainly aims at the special requirement of the solar energys application in tunnel direct lighting engineering, where the light receiver is fixed. Therefore, it has given a new automatic tracking method of polar axis type, which can effectively make the concentrator to realize the function of tracking the sun automatically with high precision and fixed-point output. Based on expounding the working principle of the automatic tracker with polar axis, meanwhile combining with the obliquely installed concentrator load, it talks about the detailed design and explanation of mechanical structure, characteristics and implementation of the suns hour angle and declination angle tracking mechanism.

In this article, we report all results obtained with a fiber scrambler on the Hamilton spectrograph at Lick Observatory. We demonstrate an improvement in the stability of the instrumental profile using this fiber scrambler. Additionally, we present data obtained with a double scrambler that further improves the stability of the instrument by a factor 2. These results show that errors related to the coupling between the telescope and the spectrograph are the dominant source of instrumental profile variability at Lick Observatory. In particular, we show a strong correlation between instrumental profile variations and hour angle, most likely due to pointing-dependent illumination of the spectrograph optics.

This paper is mainly about using the length changes of the shadows to determine the location while the length of the object is unknown. Using the solar elevation as a bridge, we build function models between solar declination, geographic latitude of the observing place, hour angle and the length of shadow, and then use Stephenson accelerate iterative method to help solve latitude positioning model, finally realize the shadow positioning.

Evacuated tube solar collectors with a heat pipe is one of the most widely used solar collectors types. Although they are characterized by a very high energy conversion efficiency there are still possibilities for improvements. One of the available options is the use of mirrors focusing the solar radiation. In order to maximize the efficiency of absorbing solar energy with the focusing mirrors their manufacturers recommend the use of the tracking system for the apparent movement of the sun. Nevertheless, such a solution has several disadvantages which include: higher investment costs and energy consumption as well as potentially higher risk of faultiness. This paper presents the results of the experimental research, on the basis of which it was possible to determine the reduction of the radiation amplification factor in the case of system without solar tracking in comparison with the maximum theoretically attainable amplification factor. The research was conducted for a single evacuated tube collector with and without the focusing mirror. The parabolic focusing mirror, made of bent aluminum sheet, was selected for this analysis. As the result of these analyses the daily amplification factor was determined and this factor emphasizes the benefit of using the focusing mirror. Moreover, it was concluded that the amplification factor is insignificant when the solar hour angle is greater than 15° while azimuth of focusing mirror is direct south at the same time.