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The study of the welding process of asymmetric parts made of Ti-6A1-4V alloy was made to expand the field of application of the process of linear friction welding and to improve the use of technology of existing assemblies. During of the study, it was found that the process of welding T-joints has features in a longer duration of the unsteady stage and an increase in the amplitude value of the shear force during the steady state. Welded joints do not contain seam flaws over the area of the welded joint, which it made unnecessary to assign an allowance along the perimeter of the welded section. The change in conditions at the joint is expressed in an increase in the microhardness of the welded seam in comparison with the Ti-6A1-4V joints, which are produced by the traditional technology more than 50 HV.

The study was carried out in 1983-1991 and covered a territory of about 10 x 10(6) km2 in various physico-geographic areas (East Fennoscandia, Northern Russian Plain, West Siberia, Central Siberia, North-Eastern Siberia, and Northern Pacific Region) in the Arctic, Subarctic, Northern-Central-Southern taiga, forest-steppe, and steppe in Northern Russia. A total of 251 strains were isolated from 1391,900 mosquitoes, identified as the California group snowshoe hare (83), Inkoo (44), and Tahyna (2) viruses; 122 strains were not completely identified. Some of the strains with uncommon antigenic composition can be natural reassortants. Fifty-two percent of strains were isolated from Aedes communis and the associate species of mosquitoes, other hosts were A. excrucians (8%), A. cantans (6.25%), A. flavescens (6.25%), A. ciprius (6.25%), A. punctor (4.5%), A. vexans (4.5%), A. cataphylla (3.6%), A. nigripes (3.6%), and A. hexodontus (2.6%). The infection rate of mosquitoes was 0.009% in the tundra, 0.012% in forest-tundra, 0.01% in Northern taiga, 0.02% in Central taiga, 0.017% in Southern taiga, 0.026% in forest-steppe, and 0.097% in steppe. The epidemic season is one month in the tundra (from the beginning of July till the beginning of August), two months in Northern taiga (July-August), and three months in Central taiga (from the second half of June till the beginning of September). The highest infection rate of mosquitoes was observed at the end of the epidemic season in all regions. SSH strains prevailed to the East from the Enisei river, whereas to the West and in the Subarctic regions INK virus predominated, SSH being rare; in the taiga the distribution was quite the opposite. TAH virus was virtually absent. Human morbidity was observed in all territories studied. The immune stratum of adult population is about 30% in the tundra and forest-tundra and about 50% in Northern and Central taiga.