Some ways to save energy during reliability tests of magnetic starters

Ways to save energy during reliability tests of magnetic starters are examined. The main ideas thereof are to use accelerated tests, optimize (reduce) the number of tested samples, etc.     

Antifrictional nanocomposites based on chemically modified UHMWPE. Part 3. Comparison of modification effect of compatibilizers on mechanical and tribotechnical properties

Two compatibilizers-vinyltrimethoxysilane (VTMS) and maleic anhydride (SMA)—are subjected to comparative analysis in respect to their effect on the mechanical and tribological properties of the composites based on chemically modified UHMWPE. The methods of IR spectroscopy, scanning differential calorimetry, and electronic microscopy are used to study the supermolecular structure of nanocomposites on the base of UHMWPE block-copolymer + 10% UHMWPE-g-VTMS. The mechanical and tribotechnical properties of these nanocomposites are further compared to those of the nanocomposites based on UHMWPE + 10% HDPE-g-SMA. It is shown that the nanocomposites based on block-copolymers with the mentioned compatibilizers have similar (spherulitic) structure and roughly equal wear resistance, being close to those of the composites based on the non-modified polymer. The wear resistance of the nanocomposites on the base of UHMWPE depends on whether the fillers are present and distributed evenly in the matrix. This defines the crystallization conditions and, as a consequence, the type of the formed supermolecular structure.     

Validation of a Method for Analysis of Aroma Compounds in Red Wine using Liquid–Liquid Extraction and GC–MS

An analytical method for determination of volatile composition of wines using sample preparation by liquid–liquid extraction and gas chromatography coupled to mass spectrometry for separation and detection has been developed and validated. Extraction of volatile compounds was performed in dichloromethane, and 1-octanol was added as an internal standard. Kékfrankos red wine produced in Villány wine region in Hungary was used as a model wine for testing and validation of the method. The developed method allowed satisfactory determination of 33 volatile compounds in the wines. Compounds analyzed include alcohols, esters, lactones, fatty acids, furans, and nitrogen compounds. The calibration curves of the four reference compounds used (2-phenyl ethanol, ethyl nonanoate, butyrolactone, and tyrosol) were linear in all cases with correlation coefficients (R ²) ranging from 0.9951 to 0.9992. The accuracy of the method was checked with a standard addition method (recovery 92.2–103 %), showing good repeatability and reproducibility (RSD?<?10 %).     

Problems of the operation of turbocompressors in an internal combustion engine and methods of increasing their reliability

The operating efficiency and reliability of internal combustion engines depends on many factors, including the operation of its components and systems. One of these elements is the turbocompressor of the engine charging system. Extensive statistical data show that the turbocompressor is one of the most frequently failing units of auxiliary engine equipment. The main causes of turbocompressor failures are breakdown of bearings or seals and body or rotor breaking. One of the solutions to increase the reliability and extend the life of turbocompressors is to improve the bearing unit with a gas magnetic support.     

Temperature dependence of ultrasound absorption in liquid metals in terms of classical and quantum theories

The equation of coefficient of ultrasound absorption is substantiated in terms of classical and quantum theories. Polytherms for liquid gold, scandium, chromium, and rhenium in a wide temperature range have been obtained for the first time.     

Dependence of the surface morphology of ultrathin bismuth films on mica substrates on the film thickness

The results of studying the surface of 15- to 100-nm-thick bismuth films by atomic-force microscopy are reported. The near-linear character of the dependences of the average surface roughness and the average height of growth patterns on the film thickness is established. It is found that the average crystallite size increases, as the film thickness is increased. A slight dependence of the crystallite size on the film thickness is observed at thicknesses in the range of 27–70 nm.     

The role of information technology in rotor balancing

The potential of multimedia interactive simulators is discussed. As an example, the simulator for a system measuring vibration parameters is considered. By means of this simulator, the components and operating principle of the measuring system may be studied in dialog mode, as is demonstrated. The application of this system not only as a measuring instrument but also for the reduction of vibration in rotating mechanisms (rotor balancing) is demonstrated.