This study is aimed to model the temperature and mass of dried mint in a Quonset type of Greenhouse Solar Dryer (GSD). The inputs including ambient air temperature (◦C), ambient air humidity (%) and ...solar radiation (Wm-2) and output data including temperature (◦C) and mass (gr) of dried mint were collected from a Quonset GSD. Artificial Neural Network (ANN) models including Multilayer Perceptron (MLP) and Radial Bias Function (RBF) and also, Gaussian Process Regression (GPR) by k-fold cross validation method were used for modeling. Levenberg-Marquardt (LM) learning algorithm with Sigmoid-Tangent transfer function by different combinations of neurons in the hidden layer were assessed for ANN models. The results showed that MLP and GPR have higher error than RBF model for predicting the temperature and mass of dried mint. The results of RBF optimization indicated that 3-15-1 and 3-18-1 topologies with using 60 and 50% of total dataset for training steps and having 0.4 and 0.3 spread factor values can predict the temperature and mass of dried mint with Mean Absolute Percentage Error (MAPE) of 1.4 and 1.82%, respectively. The results of t, F, and Kolmogorov–Smirnov tests indicated that there is no significant difference between actual and RBF output values.
•Temperature and mass of dried mint was modeled in a Quonset greenhouse solar dryer.•K-fold cross validation model was used for increase the reliability of the models.•The results indicated that Radial Bias Function (RBF) model has the lower MAPE and highest accuracy than others models.•The results of statistical analysis showed that the data obtained from RBF model have no significant difference with their actual values•RBF model can be used for predict the mass and temperature of dried mint in large scale and can help the farmers to produce the high quality outputs.
Energy lost due to shadow in the absorber plate of solar collectors can decrease the solar energy gain. In some studies, mathematical modeling was applied for calculating the energy gain reduction ...due to shadow in flat-plate solar collectors. In this study, ANN method was developed for modeling the energy gain reduction. Multilayer Perceptron (MLP) with one hidden layer and a range of neurons (5–30) by two training algorithms (LM and BR) and tangent sigmoid activation function (TanSig) were used by help of K-fold cross validation method. In the first section, six set of solar collector dimensions were used (1×1; 1×1.5; 1×2; 1.5×1.5; 1.5×2 and 2×2). In the second section all the range of dimensions were used as the inputs. The results of the first section showed that MLP with BR training algorithm can predict the energy gain reduction with minimum MAPE and RMSE in all the categories. The best results related to (1.5×1.5) dimension that achieved a MAPE of 0.15 ± 0.09% and RMASE of 4.42 ± 2.43 KJm−2 year−1, respectively. The results of the second section indicated that BR is a better training algorithm than LM. The MAPE and R2 factors for the best topology (5-27-1) were 0.0610 ± 0.0051% and 0.9999 ± 0.0001, respectively. The results of the sensitivity analysis showed that height has the biggest impact on total energy gain reduction due to shadow in flat-plate solar collectors. Finally, the results of this study indicated that by using ANN and decrease the energy lost, the efficiency of solar collectors can be increased in all applications such as industry and agriculture.
•Artificial Neural Network was applied for energy modeling in flat-plate solar collectors.•The results indicated that ANN-MLP can predict the energy gain reduction with high accuracy.•Sensitivity analysis showed that collector height has the highest effect on output modeling.
Chemical controls in hydroponic cultures are common in developing countries. However, safe agricultural production and the reduction of chemical controls play important roles in human health and the ...environment. As a clean and sustainable source of energy, solar water disinfection can realize this goal in hydroponic cultures especially in hot countries with high solar radiation. Various solar collectors have been developed for removing plant-root pathogens from water, however, the contribution of solar energy in the reduction of chemical controls has remained unknown. This research is thus aimed to investigate the potential of the sun in water disinfection and the theoretical feasibility of chemical control reduction. The typical amount of water needed to be daily disinfected in a hydroponic culture ranges from 400 to 1000 L for a 1000-square meter greenhouse. A flat plate collector (FPC) and an evacuated tube collector (ETC) were employed as conventional solar collectors to convert solar energy to heat. TRNSYS software was used to obtain the useful energy gain of the collectors. The results showed that solar energy could eliminate fungicide consumption at acceptable costs.
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•The recycled water has no side effects.•Fungicide consumption in hydroponic systems can be removed in developing countries.•Evacuated tube had 49.2% higher disinfected water compared to Flat-plate collector.•The cost of solar water disinfection was lower than the average cost of fungicides.•The cost of recycled water by flat plate collector was lower than fresh water price.
Removing plant pathogens with the sun as a free, available, clean, and sustainable source of energy is interesting. However, there is no data for disinfecting major plant pathogenic bacteria such as ...Pseudomonas syringae and Clavibacter michiganensis subsp. michiganensis by solar ultraviolet radiation. To obtain the required time for killing these bacteria at different temperatures, a bacterial suspension of active growing cells (approximately 107 CFU mL-1) was prepared and subjected to heat inside a water bath. The minimum required time for killing both of the bacteria was achieved 420, 45, and 15 min at 50, 55, and 60 °C, respectively. To examine the effect of solar ultraviolet radiation, the bacteria suspensions inside a quartz tube were exposed to the sun on a horizontal surface at the constant temperature of 50 °C within the water bath (water depth: 0.1 m). Both of the bacteria were killed after one hour by receiving 95.481 kJ m-2 ultraviolet and 2.79315 MJ m-2 solar radiation doses. The synergy of heat and solar UV could considerably reduce the killing time of the bacteria (7 to 1 hours) at 50 °C. The recommended solar UV dose is 95.481 kJ m-2 for this condition.
Shadow on the absorber plate of a flat-plate solar collector or a solar cooker box can reduce absorbed energy. The main goal of this research is to investigate the effective factors on the shadow ...formation inside a solar collector. In addition, the energy gain reduction due to shadow was calculated. The length, width (0.5–2.5) and height (0.01–0.2 m) of a solar collector, tilt angle (0.01–80°) and latitude (0.01–65°) were considered as the effective variables on the shadow formation. The sum of shadow ratio and the percentage of energy gain reduction per year were chosen as the dependent variables, and the effect of each factor was discussed. Results showed that the effective variables (strong to weak) were height, width, tilt angle, latitude and length for the sum of shadow ratio per year, and height, tilt angle, width, latitude and length for the energy gain reduction per year. The minimum and maximum energy gain reduction per year due to shadow for a solar collector with length = width = 1 and height = 0.04 m were obtained 5.23 and 21.64%, respectively. If a solar collector has a rectangular plate, the larger width is more suitable than the larger length for the shadow reduction.
•The order of effective factors on the shadow formation was presented.•The larger width is more suitable than the larger length for the shadow reduction.•The energy loss percentage per year due to shadow was calculated.•Optimum tilt angle is equal to or 5-10° less than latitude to have minimum shadow.
This study attempts to improve planting common bean in different soils. Punch planting method was used and the effect of different openers and rice husk mulch as a new idea in punch planting was ...tested. A factorial experiment in Completely randomized design was implemented in the farm of Shahrekord University. Shahrekord has a temperate and cold region with dry and warm summer. Common bean was planted to test the seedbed shape (bar, conical and grooved), sowing depth (6 and 9 cm) and the seedbed mulching (with husk and without it). The percentage of emerged plants at the time of dividing in two leaves, average height of bushes in flowering and average leaf number of each bush in flowering, the rate of height growth and the number of leaves over day and night (appropriate time of measurement from budding to flowering was considered) were measured. The grooved shape and seed coverage using rice husk mulch are recommended. There were no significant differences in depth factor.
In this study, a new soft computing model Gaussian process regression (GPR) was evaluated for modeling the total solar radiation (TSR) and exergy (Ф) in Hakkari province (the region with the highest ...sunshine duration), Turkey. For this purpose, meteorological data include average, maximum and minimum temperature (T
ave
, T
max
, T
min
), relative humidity (H), sea level pressure (P), wind speed (W), and total sunbathing time (TST), wihch were used, and sensitivity analysis was applied for evaluating the results of TSR and Ф modeling. The results showed that all the input variables have significant impact on TSR and Ф modeling. Mean absolute percentage error and coefficient of determination (R
2
) for TSR and Ф predicted by GPR were 1.51-7.02% and 0.97-0.95, respectively. Application of five-fold cross validation method showed that GPR model is able to predict the TSR and Ф with a small size of data, but for more accuracy, it is suggested to use more than 70% of total data set for training the models. This research showed that GPR has a good ability for modeling the TSR and Ф with high accuracy, and so the engineers can use this method for the TSR and Ф prediction without using the solar radiation or exergy-to-energy ratio.
A study was done to develop management and protection of soil and water. The effect of rice husk as mulch was examined for maize production. The seeds of maize were planted in two different depths (4 ...and 6 cm) and the husk of rice was injected in different conditions (lateral part of row and sub row) by a mulch planter in a farm of Shahrekord. Different mulches were placed in soil (without mulch, 200, and 300 g per a meter of length). A factorial design based on complete randomized block was performed. Indices of plant height, weight of ear, diameter of ear, length of ear, weight of ear sheath, height growth rate of plant, and seed numbers in each ear were measured. Results showed that differences were significant in the indices of plant height, height growth rate of plant, and seed numbers in each ear. In the other indices were not seen significant differences. The results also showed that there was no significant difference in the weight of ear and ear sheath. The depth of 6 cm, 300 g mulch per a meter, and injected mulch in the lateral part of row enhanced growth of plant height and seed numbers in each ear.
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