Nikolai Dmitriyevich Papaleksi (2.12.1880—03.02.1947) was a Soviet physicist and an academician (1939; corresponding member 1931). Born in Simferopol. Graduated from the University of Strasbourg (1904), where he worked until 1914, first as an assistant to K. Braun and then as a Privatdozent. There he met L. I. Mandelstam, with whom his friendship and scientific collaboration continued until the last days of his life. In 1914 he returned to Russia. In 1918–22 he worked at the Odessa Polytechnic Institute (professor from 1922), in whose organisation he took an active part together with Mandelstam. In 1922–35 he worked at the Central Radio Laboratory (Moscow, Leningrad) and at the same time in 1926–35 at the Leningrad Electrophysical and Polytechnic Institutes. From 1935 he was at the Physical and Power Engineering Institutes of the USSR Academy of Sciences (Moscow).
His research was in the field of radiophysics, radio engineering and the theory of nonlinear oscillations. Immediately after returning to Russia from Strasbourg he worked on creating the first home-built amplifying and generating electron tubes, was the first to use high-frequency induction heating for glowing their electrodes, developed tube receivers for the needs of the army, carried out research on radiotelephone communication, and more.
Together with Mandelstam he contributed to the theory of nonlinear oscillations, in particular discovered the phenomenon of resonance and asynchronous excitation, created fundamentally new generators — parametric ones — and developed interference methods of studying the propagation of radio waves. For his work on the theory of oscillations and the propagation of radio waves he was awarded the State Prize of the USSR in 1942. He took part in creating the first Soviet industrial navigation instrument based on the radio-interference method, and paid great attention to developing methods of radio measurement. In his last years he worked on the problems of radio astronomy, which was only beginning. He was one of the first to put forward, in 1942, the idea of radar ranging of the Moon.
The D. I. Mendeleev Prize (1936).