This paper studies a single degree of freedom system under free vibration and controlled by a general semiactive damping.A general integral of squared error is considered as the performance index.A one-time switching ...This paper studies a single degree of freedom system under free vibration and controlled by a general semiactive damping.A general integral of squared error is considered as the performance index.A one-time switching damping controller is proposed and optimized.The pontryagin maximum principle is used to prove that no other form of semi-active damping can provide the better performance than the proposed one-time switching damping.展开更多
3D inversion of borehole-surface electrical data for complex geo-electrical models is still a challenging problem in geophysical exploration. We have developed a program for 3D inversion to borehole-surface electrical...3D inversion of borehole-surface electrical data for complex geo-electrical models is still a challenging problem in geophysical exploration. We have developed a program for 3D inversion to borehole-surface electrical data based on the quasi-analytical approximation （QA） and re-weighted regularized conjugate gradient method （RRCG） algorithms using Visual Fortran 6.5. Application of the QA approximation to forward modeling and Frechet derivative computations speeds up the calculation dramatically. The trial calculation for synthetic data of theoretical model showed that the program is fast and highly precise.展开更多
The variational equation of the Birkhoffian system is established, by which it is proved that an integral invariant can be constructed with a known first integral. And its inverse is also correct.
This paper presents an inverse problem in analytical dynamics. The inverse problem is to construct the Lagrangian when the integrals of a system are given. Firstly, the differential equations are obtained by using the...This paper presents an inverse problem in analytical dynamics. The inverse problem is to construct the Lagrangian when the integrals of a system are given. Firstly, the differential equations are obtained by using the time derivative of the integrals. Secondly, the differential equations can be written in the Lagrange equations under certain conditions and the Lagrangian can be obtained. Finally, two examples are given to illustrate the application of the result.展开更多
For a finite dimensional slab of cold energy storage, the ice freezing process inside itat different freezing temperatures were theoretically investigated by adopting a combinationmethod of analytical and integral sol...For a finite dimensional slab of cold energy storage, the ice freezing process inside itat different freezing temperatures were theoretically investigated by adopting a combinationmethod of analytical and integral solutions. Through this study, the formulas predicting thetimely variation of ice-water interface position, the transient heat flux on the slab boundaryand the amount of clod energy stored into the slab during a freezing period were obtained-Meanwhile, the influences of freezing temperature and thickness of ice on the phase-changerate, heat fiux and charging time of the slab were also discussed in detail.展开更多
Ⅰ. INTRODUCTION The first integrals and the integral-invariants of mechanical systems are important contents of the integral theory of the equations of motion, between which there exists close
基金supported by Vietnam Academy of Science and Technology(Grant No.VAST01.04/22-23)。
文摘This paper studies a single degree of freedom system under free vibration and controlled by a general semiactive damping.A general integral of squared error is considered as the performance index.A one-time switching damping controller is proposed and optimized.The pontryagin maximum principle is used to prove that no other form of semi-active damping can provide the better performance than the proposed one-time switching damping.
文摘3D inversion of borehole-surface electrical data for complex geo-electrical models is still a challenging problem in geophysical exploration. We have developed a program for 3D inversion to borehole-surface electrical data based on the quasi-analytical approximation （QA） and re-weighted regularized conjugate gradient method （RRCG） algorithms using Visual Fortran 6.5. Application of the QA approximation to forward modeling and Frechet derivative computations speeds up the calculation dramatically. The trial calculation for synthetic data of theoretical model showed that the program is fast and highly precise.
文摘The variational equation of the Birkhoffian system is established, by which it is proved that an integral invariant can be constructed with a known first integral. And its inverse is also correct.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10272021, 10572021） and the Doctoral Programme Foundation of Institution of Higher Education of China （Grant No 20040007022）.
文摘This paper presents an inverse problem in analytical dynamics. The inverse problem is to construct the Lagrangian when the integrals of a system are given. Firstly, the differential equations are obtained by using the time derivative of the integrals. Secondly, the differential equations can be written in the Lagrange equations under certain conditions and the Lagrangian can be obtained. Finally, two examples are given to illustrate the application of the result.
文摘For a finite dimensional slab of cold energy storage, the ice freezing process inside itat different freezing temperatures were theoretically investigated by adopting a combinationmethod of analytical and integral solutions. Through this study, the formulas predicting thetimely variation of ice-water interface position, the transient heat flux on the slab boundaryand the amount of clod energy stored into the slab during a freezing period were obtained-Meanwhile, the influences of freezing temperature and thickness of ice on the phase-changerate, heat fiux and charging time of the slab were also discussed in detail.
文摘Ⅰ. INTRODUCTION The first integrals and the integral-invariants of mechanical systems are important contents of the integral theory of the equations of motion, between which there exists close
