جستجوی مقالات مرتبط با کلیدواژه « suction » در نشریات گروه « آب و خاک »

Due to many problems in the field of water supply, no study has been done on atmospheric water extraction devices. The objective of this research was to optimize the control parameters and the amounts of water produced from a physical model designed and built by the team including two-phase (refrigeration collector and sponge collector) in different atmospheric conditions were investigated. First, the effect of the sponge filter on the amount of water obtained, then the pilot in different weather conditions were studied to obtain optimal conditions. The suctions of 450 to 1400 rpm were applied at each humidity and temperature. In all the mentioned cases, the temperature of the device was studied at 2, 4, and 6 degrees below the dew point. Results showed that the sponge filter can increase the water produced by up to 15%. The first evaporator produced more water than the second evaporator. The optimal air suction speed inside the device depends on the relative humidity and temperature values. For the first and second evaporators, temperatures below 4 °C and 6 °C are optimal, respectively, and with increasing absolute humidity, the optimum suction speed increases. Parameters such as airflow velocity, number of collectors, temperature difference with dew point, and moisture absorption levels were influential in the amount of water produced. According to the qualitative study, the obtained water has a desirable quality for use in sensitive applications.

One of the most important and practical physical parameters in studies of soil water flow is Soil Water Characteristic Curve (SWCC). Measuring the soil moisture characteristic curve through the direct method is expensive and time-consuming. For this reason, a variety of indirect methods including intelligent models have been developed. In this study, the performance of three models included multilayer perceptron neural networks (MLP), cascade neural network (Cascade-NN) and gene expression programming (GEP) were evaluated and compared to estimate of SWCC. The measured data from 108 soil samples, including soil particle size distribution, soil moisture in different suctions and the bulk density were used. In all models, three different input data combinations were used. Comparison of predicted and observed values of soil moisture showed acceptable performance of all three models, however, the Cascade-NN neural network model was relatively superior. The R2 values of test phase for the best structure of the neural networks (MLP), neural networks (Cascade-NN) and gene expression programming (GEP) were 0.95, 0.96 and 0.93, respectively, and the RMSE values were 3.74, 3.25 and 4.10 %, respectively. Comparison of the results of different input data scenarios indicated the low accuracy and difference between the results of the models in the first scenario, but adding the parameters of porosity and moisture at field capacity point to the input data in the second and third scenarios, increased the accuracy and difference between the results achieved by the models. Finally, it can be emphasized that the cascade-NN model was introduced as the superior option, using all the mentioned physical data.

In this research variation of moisture and volume of an unsaturated silty soil were investigated under different suctions through experimental tests in triaxial apparatus special for unsaturated soils. The tests were carried on specimens of silty soil that made by slurry method in modified triaxial cell (triaxial cell with doubled rings) under 5 suctions from 0 to 300 kPa. Applying the target suction have been done by axis translation technic and loading the specimen under constant suction was carried by using increment loading. The results show that preconsolidation pressure will increase by increasing suction. Furthermore according to the obtained results, creation of yielding curve (LC) in space of stress- suction is possible. Also investigation of variation in slope and intercept of normal compression line showed that variation of volume and moisture of soil is function of suction changes.

Quantitative evaluation of soil compaction to improve agricultural management practices and reduce the problems caused by compaction in the environment and production is essential, and such factors as compaction effort, soil type (%clay and soil plasticity) and water content condition have a significant impact on soil compaction. This research was conducted to study the effect of soil type and compaction on soil water characteristic curve with factorial experiment using randomized complete block design and 27 treatments were provided. Treatments consisted of three soil types: clay, clay loam and sandy loam under three compaction conditions: reduced, standard, and modified were performed. The compactions were performed in the three moisture conditions: dry, optimum and wet and undisturbed samples were provided as control. Mean comparison was conducted using Duncan's test and statistical analysis was performed by SAS statistical. The results showed that at all potentials, the influence of soil type on soil water retention was significant at the p Quantitative evaluation of soil compaction to improve agricultural management practices and reduce the problems caused by compaction in the environment and production is essential, and such factors as compaction effort, soil type (%clay and soil plasticity) and water content condition have a significant impact on soil compaction. This research was conducted to study the effect of soil type and compaction on soil water characteristic curve with factorial experiment using randomized complete block design and 27 treatments were provided. Treatments consisted of three soil types: clay, clay loam and sandy loam under three compaction conditions: reduced, standard, and modified were performed. The compactions were performed in the three moisture conditions: dry, optimum and wet and undisturbed samples were provided as control. Mean comparison was conducted using Duncan's test and statistical analysis was performed by SAS statistical. The results showed that at all potentials, the influence of soil type on soil water retention was significant at the p