Vol 105, No 6 (2016)

The bearings on gasfilm lubrication system such as gasstatic air bearings are widely known; to create a lifting force they use an air forced supply into a bearing gap under excess pressure. Gas dynamic bearings that create a lifting force only at sufficiently high speed of a shaft rotation due to the Poiseuille aerodynamic effect are also widespread. Hybrid bearings may operate both in gasdynamic and gasstatic regimes. The work examines the limits of such parameters as bearing capacity, typical geometrical sizes and precision of their manufacture that define the rationality of using gasstatic, gasdynamic and hybrid air bearings; the economic effect of implementation of such bearings, in particular, in turbomachines, was estimated as well.

Vacuum tunnel diodes (VTD) are a possible alternative to a vapor compression and thermoelectric mode to generate cold. The paper cites the VTD scheme and describes the basic of cold generation using the VTD. The overview of works on developing and calculating VDT is presented. The task to reduce work of electrons liberation from electrodes that is necessary for developing high effective cooling devices on the base of the VDT is considered. Theoretical estimations of the VDT performance with cold and hot metallic electrodes made of a ntype semiconductor are carried out. The results of calculations show that using VDT as basic elements in refrigeration systems is perspective. The calculated values of a specific refrigeration capacity and refrigeration coefficient of tunnel diodes exceed the corresponding values of thermoelectric energy converters several times. A maximal thermal gradient in the VDT may reach 210 K.

A mechanical injury of potato tubers at harvesting leads to affection of them by phytopathogen microorganisms that causes big losses during storage. Using biological protection (bacteriaantagonists) immunizes the tuber cells and so has a positive influence on the process of wound reparation of potato. The paper cites the results of studies of the influence of the B.subtilis ch13 biocontrol strain and its mutant type that is resistant to antibiotic, on F.solani potato quality during cold storage. The activity of wild and mutant types as regards the main infection diseaseproducing factors during cold storage was defined. It was shown that the potato treatment with cultural liquid based on B.subtilis ch13 wild and mutant types didn’t provoke significant changes in biochemical processes behavior such as respiration intensity, change of starch content, change of ferments activity during cold storage. The biocontrol properties of wild and mutant type strains were verified concerning a provocative of potato vascular wilt. The data obtained in vitro showed that the biocontrol impact of wild and mutant types was most expressed at strain pathogen ratio 8:1. The treatment of potato with strains studied may be recommended to increase the tubers resistance to infectious deceases during cold storage.