ISSN 0025-6544, Mechanics of Solids, 2007, Vol. 42, No. 6, p. 841. c© Allerton Press, Inc., 2007.Original Russian Text c© R. V. Goldstein, 2007, published in Izvestiya Akademii Nauk. Mekhanika Tverdogo Tela, 2007, No. 6, p. 3.

Gennadii Grigor’evich Denisov:On the Occasion of his Eightieth Birthday

DOI: 10.3103/S0025654407060015

Gennadii Grigor’evich Denisov, Doctor of Physical and Mathematical Sciences, Professor, Headof Department at the Scientific Research Institute for Applied Mathematics and Cybernetics atLobachevskii Nizhnii Novgorod State University, member of the National Committee in Theoreticaland Applied Mechanics, celebrated his eightieth birthday on February 6, 2007.

Denisov is one of the most brilliant mechanicists in our country. He is known for his studies inapplied and theoretical gyroscopy and dynamics of rigid bodies and mechanical systems with distributedparameters. His work is characterized by originality and novelty of the considered problems, discoveryof qualitatively new phenomena lying beyond the framework of traditional concepts, and extraordinaryclearness and accuracy of research. Denisov has always been interested in experiments and practicallyoriented problems. Under his supervision, research on contactless suspension of bodies in magneticfields has been carried out for a long time. Magnetic suspensions were constructed for the followingprecision devices: free gyro, gyrocompass, anisotropy meter, rotational hysteresis meter, ultracentrifuge,vacuum pump, and gradiometer (which measures the Earth magnetic field inhomogeneity). Thesesuspensions were used to manufacture prototypes of instruments with unique parameters and un-precedented accuracy. Theoretical and experimental studies of the magnetic suspension have led tothe discovery of the autorotation phenomenon (where the rotor is rotated by the suspension itself),double rotation (where the motion of a rotor in a contactless suspension is the superposition of slowrotation about the dynamic symmetry axis and fast rotation about a perpendicular axis; this reducesdetrimental moments badly affecting the device accuracy), and rotor roll (which is very dangerous incontactless suspensions and sliding bearings and leads to loads destroying the machine or the device).Denisov carried out very important studies of problems concerning rotational motions of a rigid body infields of various physical nature. He also performed fundamental studies of rotational motions of a rigidbody in a resisting medium and the phenomenon of destabilization of mechanical systems by friction.Denisov gave a convincing solution of the problem as to whether waves propagating in continua havemomentum; this problem had been discussed in the literature for several decades. In the cycle of papersabout free rotational motions of viscoelastic bodies, he revealed that their dynamics is significantly morecomplicated than that of absolutely rigid bodies; he also showed the possibility of fast stability change ofthe stationary rotation axis as the angular velocity varies and gave a new interpretation of the Chandlernutation and the Earth polar motion. Denisov proposed a simple mechanical model for explaining long-period variations in the Earth rotation velocity.

G. G. Denisov is characterized by call of duty and high honesty, understanding and deep interest inpeople, and amicability. He is very generous to his students and colleagues.

The students and colleagues heartily congratulate Gennadii Grigor’evich Denisov and wish himstrong health and many new creative achievements in his activities.

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