The magnetic activity of solar-type stars generally increases with stellar rotation rate. The increase, however, saturates for fast rotation. The Babcock-Leighton mechanism of stellar dynamos saturates as well when th...The magnetic activity of solar-type stars generally increases with stellar rotation rate. The increase, however, saturates for fast rotation. The Babcock-Leighton mechanism of stellar dynamos saturates as well when the mean tilt angle of active regions approaches ninety degrees. Saturation of magnetic activity may be a consequence of this property of the Babcock-Leighton mechanism. Stellar dynamo models with a tilt angle proportional to the rotation rate are constructed to probe this idea.Two versions of the model- treating the tilt angles globally and using Joy＇s law for its latitude dependence- are considered. Both models show a saturation of dynamogenerated magnetic flux at high rotation rates. The model with latitude-dependent tilt angles also shows a change in dynamo regime in the saturation region. The new regime combines a cyclic dynamo at low latitudes with an（almost） steady polar dynamo.展开更多
氧化亚氮(N_2O)是一种重要的农田温室气体,本研究利用紫色土长期施肥试验平台,采用静态箱/气相色谱法对紫色土旱作农田冬小麦—夏玉米轮作系统的N_2O排放进行了定位观测(2012年11月至2013年9月),研究单施氮肥(N)、常规氮磷钾肥(NPK)、...氧化亚氮(N_2O)是一种重要的农田温室气体,本研究利用紫色土长期施肥试验平台,采用静态箱/气相色谱法对紫色土旱作农田冬小麦—夏玉米轮作系统的N_2O排放进行了定位观测(2012年11月至2013年9月),研究单施氮肥(N)、常规氮磷钾肥(NPK)、猪厩肥(OM)、猪厩肥配施氮磷钾肥(OMNPK)和秸秆还田配施氮磷钾肥(ICRNPK)等施肥方式对紫色土N_2O排放特征的影响;不施肥(NF)作为对照计算排放系数,以探寻紫色土地区可操作性强、环境友好的施肥方式。结果表明,所有施肥方式的N_2O排放均呈现双峰排放,峰值出现在施肥初期;玉米季N_2O排放峰值显著高于小麦季(p<0.05)。在相同的施氮水平(小麦季130 kg hm^(^(-2)),玉米季150 kg hm^(^(-2)))下,施肥方式对N_2O排放和作物产量均有显著影响(p<0.05)。N、OM、NPK、OMNPK和ICRNPK处理的土壤N_2O周年累积排放量分别为1.93、1.96、1.12、1.50和0.79 kg hm^(^(-2)),排放系数分别为0.62%、0.63%、0.33%、0.47%和0.21%,全年作物产量分别为4.35、11.95、8.39、9.77、10.93 t hm^(^(-2))。施用猪厩肥显著增加N_2O排放量,而秸秆还田在保证作物产量的同时显著降低N_2O排放量,可作为紫色土地区环境友好的施肥方式。土壤无机氮(NO_3^--N和NH_4^+-N)是N_2O排放的主要限制因子。因此,在施氮水平相同时,施肥方式对紫色土活性氮含量的影响导致N_2O排放差异显著,是土壤N_2O排放差异的根本原因。土壤孔隙充水率也是影响N_2O排放的重要环境因子,并且其对N_2O排放的影响存在阈值效应。展开更多
The crisis in the present-day geotectonics consists in that leading specialists do not recognize the rotation of the Earth. The absolute majority of tectonists base their constructions on the model of an unmovable Ea...The crisis in the present-day geotectonics consists in that leading specialists do not recognize the rotation of the Earth. The absolute majority of tectonists base their constructions on the model of an unmovable Earth. The laws of geodynamics differ essentially from the models of the unmovable or rotating Earth. As the Earth does rotate, it is to be hoped that sooner or later the researchers will be made to use a model of the rotating Earth. But the adoption of a new model is not a simple matter. It is necessary to overcome some traditions so that many tectonical regularities can be established anew on “a clean sheet”.展开更多
In this problem,simultaneous effects of Joule and viscous dissipation in three-dimensional flow of nanoliquid have been addressed in slip flow regime under time dependent rotational oscillations.Silver nanoparticles a...In this problem,simultaneous effects of Joule and viscous dissipation in three-dimensional flow of nanoliquid have been addressed in slip flow regime under time dependent rotational oscillations.Silver nanoparticles are submerged in the base fluid(water)due to their chemical and biological features.To increment the novelty,effects of cubic autocatalysis chemical reactions and radiative heat transfer have been incorporated in the related boundary layer equations.Dimensionless partial differential system is solved by employing the proposed implicit finite difference approach.Convergence conditions and stability criteria are obtained to ensure the convergence and accuracy of solutions.A comparative analysis is proposed for no-slip nanofluid flow(NSNF)and slip nanofluid flow(SNF).Variations in skin-friction coefficients,Sherwood and Nusselt numbers against physical parameters are tabulated.It is investigated that velocity slip and temperature jump significantly control drag forces and rate of heat transfer.展开更多
Dear Editors,Recently,a nanomechanical resonator with frequency of the order of 1 GHz approaches the quantum regime[1],it is getting closer to test the basic principles of quantum mechanics and very important in the s...Dear Editors,Recently,a nanomechanical resonator with frequency of the order of 1 GHz approaches the quantum regime[1],it is getting closer to test the basic principles of quantum mechanics and very important in the study of quantum information[2].Generally,a nanomechanical QED（qubit-resonator）system consists of a superconducting qubit[3]and a nanomechanical resonator.Increasing the amplitude of oscillating,the nonlinearity of nanomechanical resonator[4]is not negligible which can be exploited to generate nonclassical states in mechanical展开更多
基金supported by the Russian Foundation for Basic Research (project No. 13-02-00277)
文摘The magnetic activity of solar-type stars generally increases with stellar rotation rate. The increase, however, saturates for fast rotation. The Babcock-Leighton mechanism of stellar dynamos saturates as well when the mean tilt angle of active regions approaches ninety degrees. Saturation of magnetic activity may be a consequence of this property of the Babcock-Leighton mechanism. Stellar dynamo models with a tilt angle proportional to the rotation rate are constructed to probe this idea.Two versions of the model- treating the tilt angles globally and using Joy＇s law for its latitude dependence- are considered. Both models show a saturation of dynamogenerated magnetic flux at high rotation rates. The model with latitude-dependent tilt angles also shows a change in dynamo regime in the saturation region. The new regime combines a cyclic dynamo at low latitudes with an（almost） steady polar dynamo.
文摘氧化亚氮(N_2O)是一种重要的农田温室气体,本研究利用紫色土长期施肥试验平台,采用静态箱/气相色谱法对紫色土旱作农田冬小麦—夏玉米轮作系统的N_2O排放进行了定位观测(2012年11月至2013年9月),研究单施氮肥(N)、常规氮磷钾肥(NPK)、猪厩肥(OM)、猪厩肥配施氮磷钾肥(OMNPK)和秸秆还田配施氮磷钾肥(ICRNPK)等施肥方式对紫色土N_2O排放特征的影响;不施肥(NF)作为对照计算排放系数,以探寻紫色土地区可操作性强、环境友好的施肥方式。结果表明,所有施肥方式的N_2O排放均呈现双峰排放,峰值出现在施肥初期;玉米季N_2O排放峰值显著高于小麦季(p<0.05)。在相同的施氮水平(小麦季130 kg hm^(^(-2)),玉米季150 kg hm^(^(-2)))下,施肥方式对N_2O排放和作物产量均有显著影响(p<0.05)。N、OM、NPK、OMNPK和ICRNPK处理的土壤N_2O周年累积排放量分别为1.93、1.96、1.12、1.50和0.79 kg hm^(^(-2)),排放系数分别为0.62%、0.63%、0.33%、0.47%和0.21%,全年作物产量分别为4.35、11.95、8.39、9.77、10.93 t hm^(^(-2))。施用猪厩肥显著增加N_2O排放量,而秸秆还田在保证作物产量的同时显著降低N_2O排放量,可作为紫色土地区环境友好的施肥方式。土壤无机氮(NO_3^--N和NH_4^+-N)是N_2O排放的主要限制因子。因此,在施氮水平相同时,施肥方式对紫色土活性氮含量的影响导致N_2O排放差异显著,是土壤N_2O排放差异的根本原因。土壤孔隙充水率也是影响N_2O排放的重要环境因子,并且其对N_2O排放的影响存在阈值效应。
文摘The crisis in the present-day geotectonics consists in that leading specialists do not recognize the rotation of the Earth. The absolute majority of tectonists base their constructions on the model of an unmovable Earth. The laws of geodynamics differ essentially from the models of the unmovable or rotating Earth. As the Earth does rotate, it is to be hoped that sooner or later the researchers will be made to use a model of the rotating Earth. But the adoption of a new model is not a simple matter. It is necessary to overcome some traditions so that many tectonical regularities can be established anew on “a clean sheet”.
文摘In this problem,simultaneous effects of Joule and viscous dissipation in three-dimensional flow of nanoliquid have been addressed in slip flow regime under time dependent rotational oscillations.Silver nanoparticles are submerged in the base fluid(water)due to their chemical and biological features.To increment the novelty,effects of cubic autocatalysis chemical reactions and radiative heat transfer have been incorporated in the related boundary layer equations.Dimensionless partial differential system is solved by employing the proposed implicit finite difference approach.Convergence conditions and stability criteria are obtained to ensure the convergence and accuracy of solutions.A comparative analysis is proposed for no-slip nanofluid flow(NSNF)and slip nanofluid flow(SNF).Variations in skin-friction coefficients,Sherwood and Nusselt numbers against physical parameters are tabulated.It is investigated that velocity slip and temperature jump significantly control drag forces and rate of heat transfer.
文摘Dear Editors,Recently,a nanomechanical resonator with frequency of the order of 1 GHz approaches the quantum regime[1],it is getting closer to test the basic principles of quantum mechanics and very important in the study of quantum information[2].Generally,a nanomechanical QED（qubit-resonator）system consists of a superconducting qubit[3]and a nanomechanical resonator.Increasing the amplitude of oscillating,the nonlinearity of nanomechanical resonator[4]is not negligible which can be exploited to generate nonclassical states in mechanical
