When vegetation and bare soil coexist, in consideration of some ecological conditions of plant, the total evapotranspiration rate of the oasis and the temperature of vegetation and soil in different climatic and ecolo...When vegetation and bare soil coexist, in consideration of some ecological conditions of plant, the total evapotranspiration rate of the oasis and the temperature of vegetation and soil in different climatic and ecological conditions are calculated by using the thermal energy balance equations of vegetation and soil The evapotranspiration rate depends on climatic and ecological conditions, in some conditions, quasi-bifurcation and multi-equilibrium state appear in the solutions of evapotranspiration rate in the areas covered by small part of vegetation.展开更多
The energy balance equations in the Classical Statistical Energy Analysis (CSEA) are modified by the equations of power flow among the thtee serial coupled oscinators. The modified equations include not only the direc...The energy balance equations in the Classical Statistical Energy Analysis (CSEA) are modified by the equations of power flow among the thtee serial coupled oscinators. The modified equations include not only the direct power flow, but also the indirect power flow. The parameters in the modified equations can be expressed by those in the classical equations when the accuracy of the predicted results is able to satisfy the needs for ellgineering.展开更多
Fundamental laws and balance equations as well as C-D inequalities in continuum mechanics are carefully restudied, incompleteness of existing balance laws of angular momentum and conservation laws of energy as well as...Fundamental laws and balance equations as well as C-D inequalities in continuum mechanics are carefully restudied, incompleteness of existing balance laws of angular momentum and conservation laws of energy as well as C-D inequalities are pointed out, and finally new and more general conservation laws of energy and corresponding balance equations of energy as well as C-D inequalities in local and nonlocal asymmetric continua are presented.展开更多
In our paper we demonstrate that the filtration equation used by Gorban’ et al. for determining the maximum efficiency of plane propellers of about 30 percent for free fluids plays no role in describing the flows in ...In our paper we demonstrate that the filtration equation used by Gorban’ et al. for determining the maximum efficiency of plane propellers of about 30 percent for free fluids plays no role in describing the flows in the atmospheric boundary layer (ABL) because the ABL is mainly governed by turbulent motions. We also demonstrate that the stream tube model customarily applied to derive the Rankine-Froude theorem must be corrected in the sense of Glauert to provide an appropriate value for the axial velocity at the rotor area. Including this correction leads to the Betz-Joukowsky limit, the maximum efficiency of 59.3 percent. Thus, Gorban’ et al.’s 30% value may be valid in water, but it has to be discarded for the atmosphere. We also show that Joukowsky’s constant circulation model leads to values of the maximum efficiency which are higher than the Betz-Jow-kowsky limit if the tip speed ratio is very low. Some of these values, however, have to be rejected for physical reasons. Based on Glauert’s optimum actuator disk, and the results of the blade-element analysis by Okulov and Sørensen we also illustrate that the maximum efficiency of propeller-type wind turbines depends on tip-speed ratio and the number of blades.展开更多
基金National Key Project of Fundamental Research "The ecological environment evolution and control in western China arid area"! (G
文摘When vegetation and bare soil coexist, in consideration of some ecological conditions of plant, the total evapotranspiration rate of the oasis and the temperature of vegetation and soil in different climatic and ecological conditions are calculated by using the thermal energy balance equations of vegetation and soil The evapotranspiration rate depends on climatic and ecological conditions, in some conditions, quasi-bifurcation and multi-equilibrium state appear in the solutions of evapotranspiration rate in the areas covered by small part of vegetation.
文摘The energy balance equations in the Classical Statistical Energy Analysis (CSEA) are modified by the equations of power flow among the thtee serial coupled oscinators. The modified equations include not only the direct power flow, but also the indirect power flow. The parameters in the modified equations can be expressed by those in the classical equations when the accuracy of the predicted results is able to satisfy the needs for ellgineering.
文摘Fundamental laws and balance equations as well as C-D inequalities in continuum mechanics are carefully restudied, incompleteness of existing balance laws of angular momentum and conservation laws of energy as well as C-D inequalities are pointed out, and finally new and more general conservation laws of energy and corresponding balance equations of energy as well as C-D inequalities in local and nonlocal asymmetric continua are presented.
文摘In our paper we demonstrate that the filtration equation used by Gorban’ et al. for determining the maximum efficiency of plane propellers of about 30 percent for free fluids plays no role in describing the flows in the atmospheric boundary layer (ABL) because the ABL is mainly governed by turbulent motions. We also demonstrate that the stream tube model customarily applied to derive the Rankine-Froude theorem must be corrected in the sense of Glauert to provide an appropriate value for the axial velocity at the rotor area. Including this correction leads to the Betz-Joukowsky limit, the maximum efficiency of 59.3 percent. Thus, Gorban’ et al.’s 30% value may be valid in water, but it has to be discarded for the atmosphere. We also show that Joukowsky’s constant circulation model leads to values of the maximum efficiency which are higher than the Betz-Jow-kowsky limit if the tip speed ratio is very low. Some of these values, however, have to be rejected for physical reasons. Based on Glauert’s optimum actuator disk, and the results of the blade-element analysis by Okulov and Sørensen we also illustrate that the maximum efficiency of propeller-type wind turbines depends on tip-speed ratio and the number of blades.
