Phosphorus (P) is one of the essential nutrients for alfalfa (Medicago sativa L.) growth, but P deficiency in soil is a common phenomenon. Applying an appropriate amount of P fertilizer for alfalfa in the establishment year improves winter survival, helps achieve sustainable high yields, and promotes the best economic returns. The objective of this study was to determine the effect of different P fertilization rates (0, 22, 44, and 66 kg P ha−1) on winter survival, forage yield, and root traits of a dormant and semi-dormant alfalfa cultivar in the establishment and first production year. Our results showed that applying an appropriate amount of P fertilizer can increase forage yield and enhance the persistence of late-summer seeded alfalfa by promoting the development of crown and root traits and improving winter survival, especially for semi-dormant cultivars. Late-summer seeding and application of appropriate P fertilizer rates are effective agronomic methods for alfalfa in cold and arid winter regions, and can be used as strategies to improve fertility and stabilize soil from wind erosion for sustainable agriculture. To obtain high rate of survival in winter, the optimal P fertilization rates for the dormant and semi-dormant alfalfa cultivars in this study were 31.4 and 41.3 kg P ha−1, whereas the optimum P application rates for high forage yields were 31.3 and 31.5 kg P ha−1, respectively.
Nowadays, the zero liquid discharge of flue gas desulfurization (FGD) wastewater from coal-fired units has attracted the attention of all countries in the world. The pretreatment methods generally have the problems of high operation cost, small treatment capacity, and poor flexibility. However, the membrane method can avoid the above problems.In the current research, it has not been found that someone directly uses submerged ultrafiltration to pretreat FGD wastewater. Therefore, this paper innovatively proposed to directly use ceramic ultrafiltration membrane to treat FGD wastewater, which can ensure effluent quality and improve the flexibility of the pretreatment system. In this paper, the performance of submerged ultrafiltration membrane for the filtration of FGD wastewater from a power plant was studied to optimize the filtration performance and improve the effluent quality. The effects of operating parameters such as membrane permeate flux, aeration rate and filtration/backwashing time combination on the membrane performance were studied. The results showed that when the filtration/backwashing time combination was 15 min/30 s, with the increased in permeate flux from 55 L/(m 2 •h) to 100 L/(m 2 •h), the steady transmembrane pressure (TMP) increased from 39 kPa to 70 kPa, and the fouling rate increased significantly from 4.5 kPa/h to 7.3 kPa/h; When the aeration rate increased from 10 m 3 /(m 2 •h) to 30 m 3 /(m 2 •h), the membrane pollution was much reduced. Excessive aeration rate cannot further alleviate the membrane pollution, but also brought greater energy consumption; Increasing backwashing time can effectively inhibit the formation of gel layer on the surface of the membrane and prolong the initial stage of low-pressure operation; The rejection of suspended solids (SS) and turbidity of the equipment studied in this paper can reach more than 99% under various working conditions, which can satisfy the water quality requirements of the subsequent steps. The submerged ultrafiltration membrane was suitable for the pretreatment of FGD wastewater because it can ensure the quality of permeate under the premise of long-term operation.
In order to guarantee and optimize end-to-end Quality-of-Service (QoS) in heterogeneous and converged mobile Internet, a novel QoS routing algorithm proposed to optimize multiple QoS metrics on virtual Overlay platform based on Multi-Objective optimization is introduced at this paper. Because of the imprecise network information, the membership function and probability are combined to find a solution set to optimize the multiple QoS constraints. Simulation results confirmed that our scheme can balance the network resources better in addition to finding a QoS path than other traditional algorithms.
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