Physical research of microgravity influence on physical phenomenon in cryogenic liquids and general-purpose onboard cryogenic facility for realization of this researchaboard International Space Station

The united research plan named "Boiling" is created on the basis of several cryogenic research projects developed by experts in Russia and Ukraine for International Space Station. The "Boiling" plan includes 8 first experiments aimed at investigating the influence of microgravity on boiling processes, heat transfer and hydrodynamics in liquid helium being either under normal or superfluid conditions. The experiments are supposed to be carried out with individual cells collected inside a single cryogenic onboard experimental facility. The international research program experiments are characterized by the following features: utilization of several artificially simulated microgravity levels, owing to rotation of the experimental helium cryostat; visualization of the processes that occur in liquid helium; research of boiling and hydrodynamics both in a large volume of stationary liquid, and in a liquid flow running through a channel. Upon completion of the "Boiling" research plan, the cryogenic onboard facility created for International Space Station would be able to find its application in further scientific and experimental researches with helium

The impact of higher voltage and current harmonics on the operation of electrical systems

The article deals with the assessment of impact of higher harmonics on the operation of variablefrequency electric drive systems used in processing units at mining enterprises. Beyond that, energy efficiency and operation experience of variable-frequency electric drive usage at mining enterprises were studied. The advantages and drawbacks of implementation of variable-frequency electric drive systems were found. They include energy saving and reducing maintenance costs for processing units on one hand, as well as losses due to their incorrect selection and electromagnetic compatibility distortion on the other hand

Modification of ultra-high-molecular weight polyethylene by various fluorinating routes

Chemical-physical properties of ultra-high-molecular weight polyethylene (UHMWPE) treated by direct fluorination, direct fluorination accompanied with UV irradiation, by XeF2 and by TbF4, were tested by FTIR spectroscopy, visible spectroscopy, 19F and 13C NMR, scanning electron microscopy, XRD, and EPR. Surface energy measurements were carried out. The direct fluorination of UHMWPE is a diffusion-controlled process, but treatment with XeF2 is a kinetically controlled one. Direct fluorination and direct fluorination accompanied with UV irradiation results mainly in a formation of -CF2- groups. On the contrary, -CHF- groups are prevailing in UHMWPE treated with XeF2 and TbF4. Surface texture of UHMWPE treated with XeF2 and with F2 is quite different. Direct fluorination results in a higher polarity of the polymer surface when compared with treatment with XeF2. For the case of direct fluorination, both long-lived peroxy and fluoroalkylradicals are formed. For the case of treatment with XeF2, only fluoroalkylradicals were detected. © 2011 Wiley Periodicals, Inc.SCOPUS: ar.jinfo:eu-repo/semantics/publishe