研究了粘虫(Mythimna separate Walker)在武汉地区的种群动态及其越冬规律。结果表明,粘虫成虫在武汉地区主要有两个发生高峰,分别为4月中下旬和10月中下旬。田间粘虫幼虫发生的高峰期主要在11月至次年的3月。有再生苗的稻田内粘虫幼虫...研究了粘虫(Mythimna separate Walker)在武汉地区的种群动态及其越冬规律。结果表明,粘虫成虫在武汉地区主要有两个发生高峰,分别为4月中下旬和10月中下旬。田间粘虫幼虫发生的高峰期主要在11月至次年的3月。有再生苗的稻田内粘虫幼虫的发生量显著高于无再生苗的稻田。在越冬期间,粘虫并未进入滞育状态,而以幼虫形态越冬。粘虫幼虫在越冬期间的过冷却点与冰点均随发育程度上升而下降;死亡率则随温度的降低显著上升,两者之间的关系可用线性方程y=-1.529 1x+28.459 0表示。展开更多
Magnetic reconnection is a main process converting the magnetic energy into thermal and kinetic energy in plasmas. It is one of the fundamental problems of crucial importance not only to space plasmas physics and spac...Magnetic reconnection is a main process converting the magnetic energy into thermal and kinetic energy in plasmas. It is one of the fundamental problems of crucial importance not only to space plasmas physics and space weather studies,such as the solar flare,coronal mass ejections and magnetospheric substorms,but also to the stability analysis in magnetically confined fusion. In general,except for cases with periodical boundary conditions,three-dimensional(3D) magnetic re-connection occurs on magnetic separatrices generated by magnetic nulls. Here we briefly introduce/review the theories and some recent satellite observations of 3D magnetic reconnection. Topics to be further studied are also discussed.展开更多
Variable gauge rolling is a new process to obtain a plate for which the thickness changes continuously by continuously and dynamically adjusting the roll gap upward and downward in the rolling process.This technology ...Variable gauge rolling is a new process to obtain a plate for which the thickness changes continuously by continuously and dynamically adjusting the roll gap upward and downward in the rolling process.This technology is an efective method for producing lightweight,low-cost,and economical plates.However,variable gauge rolling is an unsteady process,and the changes in the force and deformation parameters are complex.In this research,based on the minimum energy theory of the variational principle and considering the characteristics of the roll movement and workpiece deformation comprehensively,the internal plastic deformation,friction,shear and tension powers,and the minimum result of the total power functional in upward and downward rolling are obtained with the frst integral and then with a variation of adopting the specifc plastic power and strain rate vector inner product.The analytical results of the deformation and force parameters are also established using the variational method.Then the precision of this model is certifed using the measured values in a medium plate hot rolling plant and the experimental data for Tailor Rolled Blank rolling.Good agreement is found.Additionally,the variation rule of bite angle,neutral angle,and location neutral points are shown,and the change mechanism of the friction parameter on the stress state efect coefcient is given in variable gauge rolling.This research proposes a new mathematical model for rolling process control that provides a scientifc basis and technical support for obtaining an accurate section shape in variable gauge rolling production.展开更多
文摘研究了粘虫(Mythimna separate Walker)在武汉地区的种群动态及其越冬规律。结果表明,粘虫成虫在武汉地区主要有两个发生高峰,分别为4月中下旬和10月中下旬。田间粘虫幼虫发生的高峰期主要在11月至次年的3月。有再生苗的稻田内粘虫幼虫的发生量显著高于无再生苗的稻田。在越冬期间,粘虫并未进入滞育状态,而以幼虫形态越冬。粘虫幼虫在越冬期间的过冷却点与冰点均随发育程度上升而下降;死亡率则随温度的降低显著上升,两者之间的关系可用线性方程y=-1.529 1x+28.459 0表示。
基金Supported by the National Natural Science Foundation of China (Grant Nos. 40390150, 40504021, 10575018, 40536030, 10603008 and 10778613)the National Basic Research Program of China (Grant No. 2006CB806300)+1 种基金as well as the Chinese Academy of Sciences Project (Grant No. KJCX2-YW-T04)the China Double Star-Cluster Science Team
文摘Magnetic reconnection is a main process converting the magnetic energy into thermal and kinetic energy in plasmas. It is one of the fundamental problems of crucial importance not only to space plasmas physics and space weather studies,such as the solar flare,coronal mass ejections and magnetospheric substorms,but also to the stability analysis in magnetically confined fusion. In general,except for cases with periodical boundary conditions,three-dimensional(3D) magnetic re-connection occurs on magnetic separatrices generated by magnetic nulls. Here we briefly introduce/review the theories and some recent satellite observations of 3D magnetic reconnection. Topics to be further studied are also discussed.
基金Supported by National Natural Science Foundation of China(Grant Nos.51904206,52105390,51974196,51805359)Open Research Fund from the State Key Laboratory of Rolling and Automation,Northeastern University(Grant No.2020RALKFKT011)+1 种基金Shanxi Province Science and Technology Major Projects(Grant No.20181102015)China Postdoctoral Science Foundation(Grant No.2020M670705).
文摘Variable gauge rolling is a new process to obtain a plate for which the thickness changes continuously by continuously and dynamically adjusting the roll gap upward and downward in the rolling process.This technology is an efective method for producing lightweight,low-cost,and economical plates.However,variable gauge rolling is an unsteady process,and the changes in the force and deformation parameters are complex.In this research,based on the minimum energy theory of the variational principle and considering the characteristics of the roll movement and workpiece deformation comprehensively,the internal plastic deformation,friction,shear and tension powers,and the minimum result of the total power functional in upward and downward rolling are obtained with the frst integral and then with a variation of adopting the specifc plastic power and strain rate vector inner product.The analytical results of the deformation and force parameters are also established using the variational method.Then the precision of this model is certifed using the measured values in a medium plate hot rolling plant and the experimental data for Tailor Rolled Blank rolling.Good agreement is found.Additionally,the variation rule of bite angle,neutral angle,and location neutral points are shown,and the change mechanism of the friction parameter on the stress state efect coefcient is given in variable gauge rolling.This research proposes a new mathematical model for rolling process control that provides a scientifc basis and technical support for obtaining an accurate section shape in variable gauge rolling production.