Agricultural sustainability relates directly to maintaining or enhancing soil quality. Soil quality studies in Canada during the 1980 s showed that loss of soil organic matter (SOM) and soil aggregate stability was st...Agricultural sustainability relates directly to maintaining or enhancing soil quality. Soil quality studies in Canada during the 1980 s showed that loss of soil organic matter (SOM) and soil aggregate stability was standard features of non-sustainable land management in agroecosystems. In this study total soil organic carbon (SOC), particulate organic matter (POM), POM-C as a percentage of total SOC, and aggregate stability were determined for three cultivated fields and three adjacent grassland fields to a…展开更多
Shallow slope failures induced by rainfall infiltration occur frequently, and the relevant triggering mechanisms have been widely studied.Rainfall-induced landslides are widely recognized to be caused by increases in ...Shallow slope failures induced by rainfall infiltration occur frequently, and the relevant triggering mechanisms have been widely studied.Rainfall-induced landslides are widely recognized to be caused by increases in soil weight, seepage force and pore water pressure or decreases in soil mechanical properties. However, even when all these factors are considered, some landslides still cannot be explained well. The increased pore water pressure in a slope reduces the effective stress of the soil and may trigger slope failure. Similarly, the pore gas pressure in a slope also reduces the effective stress of the soil but has been neglected in previous studies. As the viscosity of air is nearly negligible when compared with that of water, the pore gas pressure spreads faster, and its influence is wider, which is harmful for the stability of the slope. In this paper, the effects of pore gas pressure are considered in a shallow slope stability analysis, and a self-designed experiment is conducted to validate the force transfer mechanism.Numerical simulation results show that the pore gas pressure in the slope increases sharply at different locations under heavy rainfall conditions and that the pore gas pressure causes a rapid decrease in the slope safety factor. Laboratory experimental results show that the pore gas pressure throughout the whole unsaturated zone has the same value, which indicates that the gas pressure could spread quickly to the whole sample.展开更多
Investigations are directed to the development of high-power sources ofUWB （ultrawideband） radiation based on excitation of anterma arrays with bipolar voltage pulses. In the previously designed high-power UWB sourc...Investigations are directed to the development of high-power sources ofUWB （ultrawideband） radiation based on excitation of anterma arrays with bipolar voltage pulses. In the previously designed high-power UWB sources only one bipolar pulse former and different feeder systems for pulse distribution through the array elements were used. By means of this approach, a number of UWB sources were created with the bipolar voltage pulse length ranging from 0.2 to 2 ns and effective potential of radiation ranging from 0.4 to 3 MV. The approach has got a restriction related to the electrical breakdown in a bipolar voltage pulse former. A new approach to the creation of high-power UWB sources based on a multicharmel bipolar pulse former is suggested： the number of bipolar pulse formers is equal to the number of antennas in the array. The main problem in realization of this approach is a stable operation of bipolar pulse formers in order to ensure a coherent summation of radiated pulses in the far-field zone. The result of this work is the instability of-150 ps at the pulse length of 3 ns obtained in a one-channel bipolar pulse former indicating that the suggested approach is realizable.展开更多
This paper investigates the finite-time generalized outer synchronization between two complex dynamical networks with different dynamical behaviors. The two networks can be undirected or directed, and they may also co...This paper investigates the finite-time generalized outer synchronization between two complex dynamical networks with different dynamical behaviors. The two networks can be undirected or directed, and they may also contain isolated nodes and clusters. By using suitable controllers, sufficient conditions for finite-time generalized outer synchronization are derived based on the finite-time stability theory. Finally, numerical examples are examined to illustrate the effectiveness of the analytical results. The effect of control parameters on the synchronization time is also numerically demonstrated.展开更多
Li^(+) solvation structures have a decisive influence on the electrode/electrolyte interfacial properties and battery performances.Reduced salt concentration may result in an organic rich solid electrolyte interface(S...Li^(+) solvation structures have a decisive influence on the electrode/electrolyte interfacial properties and battery performances.Reduced salt concentration may result in an organic rich solid electrolyte interface(SEI)and catastrophic cycle stability,which makes low concentration electrolytes(LCEs)rather challenging.Solvents with low solvating power bring in new chances to LCEs due to the weak salt-solvent interactions.Herein,an LCE with only 0.25 mol L^(-1) salt is prepared with fluoroethylene carbonate(FEC)and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropylether(D_(2)).Molecular dynamics simulations and experiments prove that the low solvating power solvent FEC not only renders reduced desolvation energy to Li^(+) and improves the battery kinetics,but also promotes the formation of a LiF-rich SEI that hinders the electrolyte consumption.Li||Cu cell using the LCE shows a high coulombic efficiency of 99.20%,and LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)||Li cell also exhibits satisfying capacity retention of 89.93%in 200 cycles,which demonstrates the great potential of solvating power regulation in LCEs development.展开更多
基金Project supported by the USDA-NRCS National Employee Development Center, USA the Chinese Academy of Sciences for the Hundred Talents Program, and the Federal Hatch Program, USA (No.MAS00860)
文摘Agricultural sustainability relates directly to maintaining or enhancing soil quality. Soil quality studies in Canada during the 1980 s showed that loss of soil organic matter (SOM) and soil aggregate stability was standard features of non-sustainable land management in agroecosystems. In this study total soil organic carbon (SOC), particulate organic matter (POM), POM-C as a percentage of total SOC, and aggregate stability were determined for three cultivated fields and three adjacent grassland fields to a…
基金supported by National Key R&D Program of China (Grant No. 2017YFC1501100)the National Natural Science Foundation of China (Grant No. 51279090)Sponsored by Research Fund for Excellent Dissertation of China Three Gorges University
文摘Shallow slope failures induced by rainfall infiltration occur frequently, and the relevant triggering mechanisms have been widely studied.Rainfall-induced landslides are widely recognized to be caused by increases in soil weight, seepage force and pore water pressure or decreases in soil mechanical properties. However, even when all these factors are considered, some landslides still cannot be explained well. The increased pore water pressure in a slope reduces the effective stress of the soil and may trigger slope failure. Similarly, the pore gas pressure in a slope also reduces the effective stress of the soil but has been neglected in previous studies. As the viscosity of air is nearly negligible when compared with that of water, the pore gas pressure spreads faster, and its influence is wider, which is harmful for the stability of the slope. In this paper, the effects of pore gas pressure are considered in a shallow slope stability analysis, and a self-designed experiment is conducted to validate the force transfer mechanism.Numerical simulation results show that the pore gas pressure in the slope increases sharply at different locations under heavy rainfall conditions and that the pore gas pressure causes a rapid decrease in the slope safety factor. Laboratory experimental results show that the pore gas pressure throughout the whole unsaturated zone has the same value, which indicates that the gas pressure could spread quickly to the whole sample.
文摘Investigations are directed to the development of high-power sources ofUWB （ultrawideband） radiation based on excitation of anterma arrays with bipolar voltage pulses. In the previously designed high-power UWB sources only one bipolar pulse former and different feeder systems for pulse distribution through the array elements were used. By means of this approach, a number of UWB sources were created with the bipolar voltage pulse length ranging from 0.2 to 2 ns and effective potential of radiation ranging from 0.4 to 3 MV. The approach has got a restriction related to the electrical breakdown in a bipolar voltage pulse former. A new approach to the creation of high-power UWB sources based on a multicharmel bipolar pulse former is suggested： the number of bipolar pulse formers is equal to the number of antennas in the array. The main problem in realization of this approach is a stable operation of bipolar pulse formers in order to ensure a coherent summation of radiated pulses in the far-field zone. The result of this work is the instability of-150 ps at the pulse length of 3 ns obtained in a one-channel bipolar pulse former indicating that the suggested approach is realizable.
基金Supported by the National Natural Science Foundation of China under Grant Nos.61203304,61203055 and 10901145the Fundamental Research Funds for the Central Universities under Grant Nos.2011QNA26,2010LKSX04,and 2010LKSX01
文摘This paper investigates the finite-time generalized outer synchronization between two complex dynamical networks with different dynamical behaviors. The two networks can be undirected or directed, and they may also contain isolated nodes and clusters. By using suitable controllers, sufficient conditions for finite-time generalized outer synchronization are derived based on the finite-time stability theory. Finally, numerical examples are examined to illustrate the effectiveness of the analytical results. The effect of control parameters on the synchronization time is also numerically demonstrated.
基金supported by the National Key Research and Development Program of China(2019YFA0705603)the National Natural Science Foundation of China(22078341)+1 种基金the Natural Science Foundation of Hebei Province(B2020103028)financial support from York University。
文摘Li^(+) solvation structures have a decisive influence on the electrode/electrolyte interfacial properties and battery performances.Reduced salt concentration may result in an organic rich solid electrolyte interface(SEI)and catastrophic cycle stability,which makes low concentration electrolytes(LCEs)rather challenging.Solvents with low solvating power bring in new chances to LCEs due to the weak salt-solvent interactions.Herein,an LCE with only 0.25 mol L^(-1) salt is prepared with fluoroethylene carbonate(FEC)and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropylether(D_(2)).Molecular dynamics simulations and experiments prove that the low solvating power solvent FEC not only renders reduced desolvation energy to Li^(+) and improves the battery kinetics,but also promotes the formation of a LiF-rich SEI that hinders the electrolyte consumption.Li||Cu cell using the LCE shows a high coulombic efficiency of 99.20%,and LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)||Li cell also exhibits satisfying capacity retention of 89.93%in 200 cycles,which demonstrates the great potential of solvating power regulation in LCEs development.
