Sediment incipience under flows passing a backward-facing step was studied. A series of experiments were conducted to measure scouring depth, probability of sediment incipience, and instantaneous flow velocity field d...Sediment incipience under flows passing a backward-facing step was studied. A series of experiments were conducted to measure scouring depth, probability of sediment incipience, and instantaneous flow velocity field downstream of a backward-facing step. Instantaneous flow velocity fields were measured by using Particle Image Velocimetry (PIV), and an image processing method for determining probability of sediment incipience was employed to analyze the experimental data. The experimental results showed that the probability of sediment incipience was the highest near the reattachment point, even though the near-wall instantaneous flow velocity and the Reynolds stress were both much higher further downstream of the backward-facing step. The possible me- chanisms are discussed for the sediment incipience near the reattachment point.展开更多
The sandy soils of Mostaganem plateau are vety, poor in clay. They are characterized by very low fertility and water holding capacity. The addition of bentonite to these soils and the cultivation of durum wheat, in co...The sandy soils of Mostaganem plateau are vety, poor in clay. They are characterized by very low fertility and water holding capacity. The addition of bentonite to these soils and the cultivation of durum wheat, in combination with the chickpeas, are two eco-physiological strategies to rehabilitate their agricultural suitability. This study was conducted on two plant species： a local variety of durum wheat （Waha） and a legume, chickpea （variety ILC 3279）, on a substrate bentonite at 10% dose. For each stage of growth measurements of stem height, leaf area and plants vegetative nitrogen content were quantified. Changes in total nitrogen content of durum wheat grown in substrates amended with 10% bentonite or not during the development of durum wheat in monoculture and in association with the chickpeas were analyzed. The results showed that the total nitrogen content of durum wheat was significantly higher at three leaves and tailoring stages, when durum wheat was associated with chickpea in the same soil. However, the results showed no difference during the lifting and two leaves stages. There was also a positive effect of treatment at 10% of bentonite on the plant total nitrogen content regardless of the stage and the culture system.展开更多
基金National Natural Science Foundation of China (No.10602017)Maritime Research Center and DHI-NTU Center of Nanyang Technological University, Singapore
文摘Sediment incipience under flows passing a backward-facing step was studied. A series of experiments were conducted to measure scouring depth, probability of sediment incipience, and instantaneous flow velocity field downstream of a backward-facing step. Instantaneous flow velocity fields were measured by using Particle Image Velocimetry (PIV), and an image processing method for determining probability of sediment incipience was employed to analyze the experimental data. The experimental results showed that the probability of sediment incipience was the highest near the reattachment point, even though the near-wall instantaneous flow velocity and the Reynolds stress were both much higher further downstream of the backward-facing step. The possible me- chanisms are discussed for the sediment incipience near the reattachment point.
文摘The sandy soils of Mostaganem plateau are vety, poor in clay. They are characterized by very low fertility and water holding capacity. The addition of bentonite to these soils and the cultivation of durum wheat, in combination with the chickpeas, are two eco-physiological strategies to rehabilitate their agricultural suitability. This study was conducted on two plant species： a local variety of durum wheat （Waha） and a legume, chickpea （variety ILC 3279）, on a substrate bentonite at 10% dose. For each stage of growth measurements of stem height, leaf area and plants vegetative nitrogen content were quantified. Changes in total nitrogen content of durum wheat grown in substrates amended with 10% bentonite or not during the development of durum wheat in monoculture and in association with the chickpeas were analyzed. The results showed that the total nitrogen content of durum wheat was significantly higher at three leaves and tailoring stages, when durum wheat was associated with chickpea in the same soil. However, the results showed no difference during the lifting and two leaves stages. There was also a positive effect of treatment at 10% of bentonite on the plant total nitrogen content regardless of the stage and the culture system.
