Many factors affect soil erosion and runoff generation. However, the role of some factors such as freeze-thaw (FT) processes has not been well considered yet. The present study therefore aimed to simulate and explain the effect of FT cycle on runoff generation and More
Many factors affect soil erosion and runoff generation. However, the role of some factors such as freeze-thaw (FT) processes has not been well considered yet. The present study therefore aimed to simulate and explain the effect of FT cycle on runoff generation and sediment yield under rainfall simulation condition. Towards this attempt, air and different soil depth temperatures were analyzed in natural condition and 10 cm soil depth was targeted for the soil laboratory experiments. A FT cycle with three and two days for freezing and thawing was taken place. The rainfall storm with 1.2 mm/min and 30 min duration was simulated and conducted for three treatments in soil erosion and rainfall simulation laboratory of Tarbiat Modares University. The results showed that the induced FT cycle soil had a distinct and significant behavior and different from that seen for the control plot. So that, the times of runoff generation in freezed and FT cycle treatments were 2.74 and 3.25 times less, respectively, compared to that reported for the control plots. The runoff volume and sediment yield were also respectively reported in turn of 1.46 and 1.16 and, 11.92 and 2.65 times more for freezed and FT cycle induced treatments compared to those recorded for control plots. Ice lenses and frost heaves plus creating situations close to soil saturation after FT cycle were the most effective factors in distinct behavior of soil induced by Freezingand FT cycle.
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This research presents a solar energy recovery system consisting of three main parts including a thermoelectric generator, a convex lens, and a thermal heatsink. The most important feature of the proposed recycling system is its simple structure and design, without comp More
This research presents a solar energy recovery system consisting of three main parts including a thermoelectric generator, a convex lens, and a thermal heatsink. The most important feature of the proposed recycling system is its simple structure and design, without complexity and reasonable price. In the design of the recycling system, one side of the thermoelectric is hotted by solar energy, and the other side of the thermoelectric is cooled by the heatsink which is exposed to river water. The temperature gradient is created on both sides of the thermoelectric, which recycles solar energy, resulting in voltage and electrical power. To evaluate the proposed system for solar energy recovery, after its construction, all data and effective parameters on both sides of the thermoelectric generator during the test are recorded every ten minutes, and then the recycling system and information recorded in the engineering equation solver software as codes. Based on the experimental tests, the maximum output voltage of the recycling circuit at a temperature difference of 25 ° C is reported to be 229 mV.
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If the saturated sand lenses are placed around the tunnels under the force of the earthquake, liquefaction will occur in them. This will cause settlement of the ground surface and changes in forces and anchors on the tunnel lining. For this purpose, it is important to e More
If the saturated sand lenses are placed around the tunnels under the force of the earthquake, liquefaction will occur in them. This will cause settlement of the ground surface and changes in forces and anchors on the tunnel lining. For this purpose, it is important to evaluate the change of different parameters of the sand lens and the change of the thickness of the tunnel lining in the part of the sand lens and the changes in the diameter and depth of the tunnel as well as the location of the sand lens considering the tunnel inside it. Therefore, this article investigates the mentioned changes in shallow tunnels in the location of sand lens in flowing soils surrounded by clay. In this article, FLAC 3D software is used to determine changes in pore water pressure and effective stress reduction after sand lens liquefaction. Based on the obtained results, if the sand lenses are placed at a depth of less than 10 meters, they increase the land surface subsidence by 36% compared to the reference model B, with an increase of 2 meters in the depth of the sand lens compared to the reference model B, the value of the maximum bending anchor and axial force on the tunnel lining increases by 35.7% and 14.4%, respectively, in the sand lens part. The findings of the present study can be very useful in the decision-making process of tunnels that are dug inside flowing sand lenses.
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In the present study, a total number of 10 guinea pig eyes were studied macroscopically and microscopically (with staining by H&E, Verhoeff, Van Gieson, and P.A.S.). The results showed that posterior surface of lens was more convex than anterior surface. The average More
In the present study, a total number of 10 guinea pig eyes were studied macroscopically and microscopically (with staining by H&E, Verhoeff, Van Gieson, and P.A.S.). The results showed that posterior surface of lens was more convex than anterior surface. The average lens diameter and thickness were respectively measured as 0.61±0.02 and 0.45±0.024 centimeters. The average ciliary body thickness was measured as 0.25±0.03 centimeters. In addition, the ciliary body’s mean external diameter as 0.92±0.03 centimeters and the number of ciliary body process is about 68. The epithelium of lens was cuboid and the lens capsule as positive PAS reaction intensively. The anterior surface of capsule was thicker than posterior one. The lens fibers in the central part were thicker than other parts and the elastic fibers in lens were not observed. The epithelium of ciliary processes has two layers; the superficial layer was non-pigmented and culumnar with eosinophilic cytoplasm. Deep layer of epithelium was non-pigmented and cuboid with clear cytoplasm. There was not any pigments in subepithelial tissue. The subciliary process’s connective tissue had smooth muscle with longitudinal sections. There are a lot of thick elastic fibers in the ciliary body tissue. In conclusion, the major distinction of guinea pig in addition to differences of the lens and ciliary body’s dimensions was lack of pigmentation of epithelial cells of ciliary body.
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