scholarly journals Theoretical study of Linke's Turbidity at Some Iraqi Sites Based on Solar Radiation

2021 ◽  
Vol 13 (01) ◽  
pp. 12-23
Author(s):  
Ali Shkhair Younus ◽  
◽  
Sahib Neamh Abdul Wahid ◽  
Keyword(s):  
Solar Radiation ◽  
Winter Season ◽  
Total Solar Radiation ◽  
The Sun ◽  
Average Amount ◽  
Diffuse Solar Radiation ◽  
The North ◽  
The Hours ◽  
South Of Iraq ◽  
North And South

Turbidity was calculated by solar irradiance (Linke's Turbidity) for sixteen Iraqi sites. These sites were distributed among middle, north and south of Iraq. We have updated these results of turbidity by depending on direct solar radiation, diffuse solar radiation, total solar radiation, and solar constant as inputs for mathematical models in computer programs. The latter calculations taking into account the hours of actual sun shine, hours of theoretical sun shine of the sun, the angle of the sun's rays, and the angle of the sun during the months of the year. The results showed that turbidity in the Iraqi sites which considered in this research depends mainly on the months of the year regardless of the fact that this site is located in the north, middle or south of Iraq. The amount of turbidity is at its greatest value during the winter season, specifically the month of December, where the average turbidity varied for those sites. In latter month the turbidity was ranged from (4.85 to 5.73), while in January it ranged from (4.75 to 5.72), then it began to decrease until the value of turbidity in most sites reached its lowest level in September, where the average turbidity of the studied sites varied (except for the site of Najaf) in this month (2.82 - 3.10) While the Najaf site was unique in registering the lowest average amount of turbidity in June by (3.25). The results showed that the turbidity in all sites included in this research ranges between (2.82 - 5.73) during the year.

Effect of Tracking Flat Reflector Using Novel Auxiliary Drive Mechanism on the Performance of Stationary Photovoltaic Module

2007 ◽  
Author(s):  
Sudhir Kulkarni ◽  
Saurabh Tonapi ◽  
Pierre Larochelle ◽  
Kunal Mitra
Keyword(s):  
Power Generation ◽  
Solar Radiation ◽  
Total Solar Radiation ◽  
The Sun ◽  
Drive Mechanism ◽  
Diffuse Solar Radiation ◽  
Pv Array ◽  
Pv Module ◽  
Continuous Power ◽  
Spherical Mechanism

General ways of cost reduction in solar power generation are Solar Tracked Photovoltaic (PV) arrays and concentrator systems. The PV array tracking becomes infeasible with increase in the size of the array and concentrated system is ineffective for continuous power generation as it requires external cooling system. Proposed approach here is to employ a novel auxiliary mirror drive mechanism to track the sun and reflect the rays on to stationary PV arrays. The performance is compared with same PV module without reflector under the same environmental conditions. Solarex SX 38 PV module and cleardome solar reflector (96% reflectivity) are used for the experiments. PV module is connected to electrical load through Maximum Power Point Tracker (MPPT) and data acquisition system for voltage and current measurements. Incident radiation is measured using Li-Cor pyranometers located on the plane of the module and horizontal plane. A shadow band device is used for the measurement of diffuse solar radiation. The PV module is placed facing south at a tilt angle equal to the latitude angle. A reflector is placed facing north and oriented using the novel Mirror Positioning Device (MPD). The MPD is a five bar spherical mechanism used for solar tracking. This mechanism has two degrees of freedom which allows for tracking the sun along its azimuth and altitude. The mechanism is driven by two servo motors which actuate two links. The actuated link 1 helps in achieving the altitude gained by the sun while the actuated link 2 helps to attain the azimuth (or horizontal movement). The reason for using a spherical mechanism is due to the virtue of its architecture; it allows for carrying a larger payload and also helps in reducing weight. Its advantages are that it requires less power than traditional PV array tracking; there is no need for sensors to determine the position of the sun and also that it being a two degree of freedom spherical mechanism yields a large singularity free mirror orienting workspace. Solar radiation, efficiency, and temperature are plotted as a function of time for analysis. Average diffuse solar radiation is found to be in the range of 15 to 20% of total solar radiation. Different experiments are performed to find out the optimum cycle speed for reflector. Measurements show that output from the PV panel can be increased in the order of 22% with the use of tracking reflector. This work has succeeded in its goal in realization that the considerable increase in output power from PV modules can be achieved.

scholarly journals Improved empirical models for estimating surface direct and diffuse solar radiation at monthly and daily level: A case study in North China

2019 ◽  
Vol 43 (1) ◽  
pp. 80-94 ◽  
Author(s):  
Yao Feng ◽  
Dongmei Chen ◽  
Xinyi Zhao
Keyword(s):  
Solar Radiation ◽  
North China ◽  
Field Measurements ◽  
Empirical Models ◽  
Energy Utilization ◽  
Total Solar Radiation ◽  
Diffuse Solar Radiation ◽  
Precise Knowledge ◽  
The Impact

Precise knowledge of direct and diffuse solar radiation is important for energy utilization and agricultural activities. However, field measurements in most areas of the world are only for total solar radiation. The satellite-retrieved direct and diffuse solar radiation show poor performance under overcast skies. Therefore, better empirical models are needed to estimate direct and diffuse solar radiation by considering the impact of aerosols over polluted regions. A case study is conducted in North China with the ground-measured solar radiation and satellite-retrieved aerosol optical depth to improve new empirical models at monthly (from 2000 to 2016) and daily (from 2006 to 2009) level. The improved empirical models are validated using the field measurements and compared with the existing models. Results suggest that these models perform well in estimating direct solar radiation at monthly ( R2 = 0.86–0.91, RMSE = 0.76–0.83 MJ/m2) and daily ( R2 = 0.91–0.94, RMSE = 1.51–1.64 MJ/m2) level. The accuracy of estimated monthly ( R2 = 0.95–0.96, RMSE = 0.57–0.65 MJ/m2) and daily ( R2 = 0.91–0.93, RMSE = 1.09–1.15 MJ/m2) diffuse solar radiation, particularly the maximum diffuse solar radiation value, has been improved compared to the existing models. The models presented in this study can be useful in the improvement and evaluation of solar radiation dataset over polluted regions similar to North China.

Observations near the north and south poles of bursts of cosmic rays from the sun

1961 ◽  
Vol 271 (4) ◽  
pp. 317-326 ◽  
Author(s):  
M.A. Pomerantz ◽  
S.P. Duggal ◽  
K. Nagashima
Keyword(s):  
Cosmic Rays ◽  
The Sun ◽  
The North ◽  
North And South

Developing and Evaluation of Various Correlations for Diffuse Solar Radiation for Urla (Izmir, Turkey)

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
Orhan Ekren
Keyword(s):  
Solar Radiation ◽  
Solar Energy ◽  
Tracking System ◽  
Diffuse Radiation ◽  
Energy System ◽  
Solar Irradiation ◽  
Total Solar Radiation ◽  
Total Radiation ◽  
Diffuse Solar Radiation ◽  
Tilted Surface

Characteristics of site-specific solar irradiation is required to optimize a solar energy system. If no tracking system is used, the amount of electricity or heat produced by solar energy depends on the total solar radiation on a tilted surface. Although pyranometer measures direct plus diffuse solar radiation on a horizontal surface, there are many locations where diffuse radiation is not measured. Also, diffuse radiation is necessary to determine the total radiation on a tilted surface. Therefore, in this study, new correlations for diffuse solar radiation is proposed as a function of atmospheric parameters for Urla (Izmir, Turkey). After applying the statistical procedure on the measured data, seven new correlations are proposed for the ratio of hourly average diffuse and total radiation. Also, the ratio of monthly average daily diffuse and total radiation for this region is proposed.

scholarly journals Meristic character variability among populations of Silurus triostegus Heckel, 1843 from the Euphrates, Tigris, and Shatt al-Arab Rivers, Iraq

2017 ◽  
Vol 25 (1) ◽  
pp. 21-31
Author(s):  
Laith A. Jawad ◽  
Alessandro Ligas ◽  
Muhammad I.G. Al-Janabi
Keyword(s):  
High Latitudes ◽  
Gill Rakers ◽  
Euphrates River ◽  
The North ◽  
Fin Rays ◽  
The Mean ◽  
South Of Iraq ◽  
North And South ◽  
Entire Distribution ◽  
Pelvic Fin

Abstract Variation in the numbers of pectoral fin spines and rays, pelvic fin rays, gill rakers on the first gill arch, anal fin rays, and the number of vertebrae of Silurus triostegus Heckel were examined in specimens from 16 localities that span its entire distribution range in the Tigris, Euphrates, and Shatt al-Arab rivers in Iraq. The mean number of the six meristic traits increases toward high latitudes with maximum and minimum values in the north and south of Iraq. Based on cluster analysis and PCA, the Mesopotamian river samples were clearly separated into three distinct groups. The upper Tigris populations were isolated from those of the middle and southern populations of this river and from those of the Euphrates River. Possible reasons for such differentiation among populations are discussed, and the integration of research on this species among the countries neighboring Iraq is required.

Periodic Variation of the North-South Asymmetry of Solar Activity Phenomena

2000 ◽  
Vol 179 ◽  
pp. 173-176
Author(s):  
V. K. Verma
Keyword(s):  
Solar Activity ◽  
Periodic Variation ◽  
The Sun ◽  
Solar Cycles ◽  
The North ◽  
Sunspot Data ◽  
Flare Index ◽  
North And South ◽  
South Asymmetry

AbstractWe report here a study of various solar activity phenomena occurring in both north and south hemispheres of the Sun during solar cycles 8–23. In the study we have used sunspot data for the period 1832–1976, flare index data for the period 1936–1993, Hα flare data 1993–1998 and solar active prominences data for the period 1957–1998. Earlier Verma reported long-term cyclic period in N-S asymmetry and also that the N-S asymmetry of solar activity phenomena during solar cycles 21, 22, 23 and 24 will be south dominated and the N-S asymmetry will shift to north hemisphere in solar cycle 25. The present study shows that the N-S asymmetry during solar cycles 22 and 23 are southern dominated as suggested by Verma.

scholarly journals Efficiency of using solar tracking systems with two degrees of freedom

2020 ◽  
Vol 7 (1) ◽  
pp. 46-50
Author(s):  
O.V. Pidhorodetskiy ◽  
◽  
E.V. Titova ◽  
V.I. Kravets ◽  
◽  
...  
Keyword(s):  
Solar Radiation ◽  
Solar Energy ◽  
Power Plants ◽  
Degrees Of Freedom ◽  
Economic Effect ◽  
Winter Season ◽  
Radiation Balance ◽  
The Sun ◽  
Tracking Systems ◽  
Two Degrees Of Freedom

The article touches upon the problem of increasing the efficiency of the functioning of solar power plants. An effective way to increase the flow of solar energy to the inclined plane of photo converters is the introduction of systems that are able to change the spatial orientation of solar modules during daylight hours in the vertical and horizontal planes. The work focuses on determining the quantitative indicators of incident solar energy when using a space-oriented and stationary installation system of photo modules. The calculation method chosen by the authors allows finding the intensity of solar radiation on the surface of a plane oriented in any direction, for a typical day and under different weather conditions. The calculation procedure is built for: determining the declination of the Sun to the northern hemisphere, the time of sunrise and sunset of the celestial body for the selected area, establishing the height of the Sun and the angle of incidence of solar radiation on a surface of 1 m2, oriented at different angles to the horizontal plane. Calculation of total solar insolation is performed by integrating the found values of the radiation balance over a specific duration of daylight. A comparison of the intensity of the supply of solar energy to a stationary and oriented plane during one year of operation is presented. It has been established that the most favourable period of time for maximum use of the potential of tracking systems is determined by the length of daylight hours. So, the highest efficiency of using oriented technology for installing photomodules becomes available in spring and summer. The lowest efficiency of such systems relative to stationary counterparts is observed during the winter season, when the daylight hours are minimal, and therefore, the change of the mode of operation of the system at appropriate intervals is required. The calculations allow predicting the economic effect of the introduction of orientation systems for solar photomodules with two degrees of freedom, depending on the performance and cost of individual systems. Keywords: solar energy, tracking, photovoltaic converter, radiation balance, radiation.

scholarly journals SOIL CHEMICAL ATTRIBUTES IN RESPONSE TO TREE DISTANCE AND SUN-EXPOSED FACES AFTER THE IMPLANTATION OF AN INTEGRATED CROP-LIVESTOCK-FORESTRY SYSTEM

2018 ◽  
Vol 42 (4) ◽  
Author(s):  
Guilherme Musse Moreira ◽  
Júlio César Lima Neves ◽  
Ciro Augusto de Souza Magalhães ◽  
Austeclinio Lopes de Farias Neto ◽  
Geronimo Sauer ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Nutrient Availability ◽  
Soil Nutrient ◽  
Amazon Forest ◽  
Soil Nutrient Availability ◽  
Mato Grosso ◽  
The North ◽  
Chemical Attributes ◽  
Tree Component ◽  
North And South

ABSTRACT The use of trees in integrated crop-livestock-forestry systems (ICLF) allows diversifying production, increasing profitability per area, and providing a higher animal comfort. However, the influence of tree component on soil chemical attributes in this system is still little studied. This study aimed to assess the effect of trees and sun-exposed faces to solar radiation on soil nutrient availability at different distances of tree rows in an integrated crop-livestock-forestry system. This study was carried out in the northern Mato Grosso State, Brazil, in the Cerrado - Amazon Forest transition region in an ICLF with the tree component formed by three eucalyptus rows. The assessment carried out in the second year of ICLF implantation considered the effect of tree distances (3, 6, 10, and 15 m) on two sun-exposed faces to solar radiation (north and south) on the main soil chemical attributes. Soil sampling was performed at depths of 0-0.05, 0.05-0.10, 0.10-0.20, and 0.20-0.30 m. The results indicated a homogeneity of the average nutrient contents obtained in the north and south-exposed faces, as well as in the comparison of the same distances in both assessed sun-exposed faces. Effects of trees on soil chemical attributes were verified only when an isolated analysis was carried out in the north-exposed face for K and Al contents. For these attributes, the increased distance in the row was associated with a reduction in their contents in the more superficial and deeper layers, respectively. Trees do not significantly affect soil nutrient availability in the first years of ICLF implantation in systems with homogeneity of solar radiation incidence in the sun-exposed faces although there may be discrete nutrient reductions with the distance of trees.

scholarly journals Hourly 5-km surface total and diffuse solar radiation in China, 2007–2018

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Hou Jiang ◽  
Ning Lu ◽  
Jun Qin ◽  
Ling Yao
Keyword(s):  
Solar Radiation ◽  
Correlation Coefficient ◽  
Numerical Models ◽  
Regional Climate ◽  
Terrestrial Ecosystem ◽  
Mean Bias Error ◽  
Bias Error ◽  
Total Solar Radiation ◽  
Surface Solar Radiation ◽  
Diffuse Solar Radiation

Abstract Surface solar radiation is an indispensable parameter for numerical models, and the diffuse component contributes to the carbon uptake in ecosystems. We generated a 12-year (2007–2018) hourly dataset from Multi-functional Transport Satellite (MTSAT) satellite observations, including surface total solar radiation (Rs) and diffuse radiation (Rdif), with 5-km spatial resolution through deep learning techniques. The used deep network tacks the integration of spatial pattern and the simulation of complex radiation transfer by combining convolutional neural network and multi-layer perceptron. Validation against ground measurements shows the correlation coefficient, mean bias error and root mean square error are 0.94, 2.48 W/m2 and 89.75 W/m2 for hourly Rs and 0.85, 8.63 W/m2 and 66.14 W/m2 for hourly Rdif, respectively. The correlation coefficient of Rs and Rdif increases to 0.94 (0.96) and 0.89 (0.92) at daily (monthly) scales, respectively. The spatially continuous hourly maps accurately reflect regional differences and restore the diurnal cycles of solar radiation at fine resolution. This dataset can be valuable for studies on regional climate changes, terrestrial ecosystem simulations and photovoltaic applications.

Estimation of Solar Radiation for Crop Drying in Uyo, Nigeria Using a Mathematical Model

2013 ◽  
Vol 824 ◽  
pp. 420-428 ◽  
Author(s):  
Akindele Folarin Alonge ◽  
Onwude Daniel Iroemeha
Keyword(s):  
Solar Radiation ◽  
Deterministic Model ◽  
Object Oriented Programming ◽  
Total Solar Radiation ◽  
Daily Data ◽  
Local Computer ◽  
The Hours ◽  
Suitable Object ◽  
Oriented Programming Language

Insolation available to dry crop on any clear-day was mathematically simulated on a local computer, using a suitable object oriented programming language (JAVA), for predicting solar radiation available at any given time in the Northern hemisphere on longitude East on Greenwich. Uyo, AkwaIbom State, Nigeria was used as a case study. The deterministic model was developed using set of equations and taking into consideration the factors of two components of solar radiation: The beam and diffused components. The results of the model rapidly produced hourly, monthly and daily data of insolation on horizontal earth surface and was verified and validated using existing solar radiation data, gotten from the Nigeria Metrological Station, Department of Geography and Regional Planning, University of Uyo, Nigeria. Predicted results showed that total solar radiation on any clear-day of the year in Uyo, Nigeria is sufficient to dry crops provided the crops are dried between the hours of 9a.m. and 4 p.m. March, April and September were found to be the best months for crop drying, while August and December recorded the lowest solar insolation.

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