Quantum mechanics in rotating frames. I. The impossibility of rigid flow

1978 ◽  
Vol 56 (4) ◽  
pp. 468-479 ◽  
Author(s):  
P. Gulshani ◽  
D. J. Rowe

The Hamiltonian describing a system of particles in a rotating coordinate system is derived and it is shown that the simple classical solution of rigid flow is forbidden in quantum mechanics, even at very low angular velocities. This effect is closely parallel to the Aharonov–Bohm effect, which likewise has its origin in the single-valuedness requirement of the wave function. An analytical approach to perturbation theory is used to include the effects of the Coriolis and centrifugal forces and to derive the current flows for some independent-particle systems, that is, for the Inglis cranking model. It is shown, by explicit construction, that the currents are not rigid even when the moment of inertia assumes the rigid-flow value, as it does for the harmonic oscillator single-particle potential under conditions of self-consistency. Furthermore, it is shown that, for a more general potential, even the moment of inertia is not rigid.

The problem of nucleons moving independently in a rotating oscillator potential can be solved exactly by elementary methods. The resulting simple expressions for the energy and moment of inertia are valid for all angular velocities, and will be of use in estimating corrections to the finer details of the rotational spectra of nuclei. The motion is analyzed in terms of the orbits of the individual nucleons. The rotation of the average field induces particle motions with positive and negative orbital angular momenta, which are large in comparison with the angular momenta associated with the rotation of the orbits with the average angular velocity. The ‘rigid’ value of the moment of inertia of the independent particle motion near an equilibrium deformation results from the cancellation of these much larger orbital contributions. The orbits ‘outside’ closed shells contribute to the moment of inertia a value practically equal to that of a rigid body with the mass distribution of the whole nucleus. On account of cancellations, the resultant contribution of the deformed, closed-shell core is only a small fraction of the total value.


1982 ◽  
Author(s):  
Carol Zahner ◽  
M. Stephen Kaminaka

Author(s):  
Chuanwen Zhang ◽  
Guangxu Zhou ◽  
Ting Yang ◽  
Ningran Song ◽  
Xinli Wang ◽  
...  

1971 ◽  
Vol 34 (4) ◽  
pp. 255-256 ◽  
Author(s):  
S.A. Hjorth ◽  
J. Oppelstrup ◽  
G. Ehrling

1993 ◽  
Vol 21 (4) ◽  
pp. 355-366 ◽  
Author(s):  
David L. Wallach

The moment of inertia of a plane lamina about any axis not in this plane can be easily calculated if the moments of inertia about two mutually perpendicular axes in the plane are known. Then one can conclude that the moments of inertia of regular polygons and polyhedra have symmetry about a line or point, respectively, about their centres of mass. Furthermore, the moment of inertia about the apex of a right pyramid with a regular polygon base is dependent only on the angle the axis makes with the altitude. From this last statement, the calculation of the centre of mass moments of inertia of polyhedra becomes very easy.


2012 ◽  
Vol 253-255 ◽  
pp. 2102-2106 ◽  
Author(s):  
Xu Juan Yang ◽  
Zong Hua Wu ◽  
Zhao Jun Li ◽  
Gan Wei Cai

A torsional vibration model of the slewing mechanism of a hydraulic excavator is developed to predict its free vibration characteristics with consideration of many fundamental factors, such as the mesh stiffness of gear pairs, the coupling relationship of a two stage planetary gear trains and the variety of moment of inertia of the input end caused by the motion of work equipment. The natural frequencies are solved using the corresponding eigenvalue problem. Taking the moment of inertia of the input end for example to illustrate the relationship between the natural frequencies of the slewing mechanism and its parameters, based on the simulation results, just the first order frequency varies significantly with the moment of inertia of the input end of the slewing mechanism.


Author(s):  
Tao Wang ◽  
Jikun Li ◽  
Yuwen Liu

The control of permanent magnet synchronous motor has become an important research, and many control methods have been developed because of its high efficiency and energy-saving characteristics. This article proposes a new motor control approach based on synergetic approach in control theory (SACT) and sliding-mode control (SMC). Since the load torque of the motor will change, the moment of inertia will increase in the experiment. The load torque is estimated by the sliding-mode observer. The moment of inertia is calculated by the least squares method by adding a forgetting factor. The practical application of synergetic control theory broadens the train of thought to meet the demand of high-performance motor drive further. The simulation and experimental results show that this control scheme in this article can improve the transient response and system robustness of dynamic systems.


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