The types of machine reliability tests and the applicability of the test plans are discussed. On this basis, a methodology for experimental testing of the reliability of the machines is proposed and the interrelation of the elements of the methodology is shown.
After general theoretical introduction referred on port related emissions, in this paper, special focus is given to emission to air in a seaport caused by dispersion of cargo through handling operation with dry bulk cargoes (and their storing on open storage area). In that context, on the concrete object of research – handling operations with dry bulk cargoes in the Port of Bar (Montenegro) – are analyzed elements which determine quantities of dispersed cargoes by handling operations types and their phases, considered intensity of emissions to air caused by cargo dispersion and recognized principal direction of action in order to reduce that dispersion (and consequent emissions to air).
Modeling in PSCAD / EMTDS of traveling waves in a single-wire power transmission line is considered. Traveling waves of the terrestrial mode are generated at the beginning and in the middle of the line in different ways. The effects of dispersion, w hich lead to the dependence of the recording time of a traveling wave on the value of the registration threshold and on the distance traveled, are considered. The term of instantaneous and average speed is introduced. The values of the instantaneous speed with multiple runs of the line length drop to 250 m / μs. The average speed of a traveling wave with a single run of the line decreases by 4-6% relative to the speed of light for real thresholds of signal registration.
Detonation synthesis nanodiamonds have been widely used in modern science and technology. Such kind of nanodiamonds can be obtained either from the carbon explosive molecule (DND) or from a mixture of explosives with the addition of graphite or soot (DALAN). Possessing nanoscale and high surface energy, diamonds have a structural and dispersion-strengthening effect being in contact with any materials. In many ways, the applications of nanodiamonds are determined by their dispersion, reactivity, and aggregative state in various environments. The given scientific research investigated the properties of industrial DND and DALAN produced by JSC RPE “SIDAL”, being one of the leading manufacturers in Russia. There were estimated the following properties: crystallites sizes; elemental composition; thermal stability; specific surface area; unit sizes.
The recent subject of great research challenge and one of the most active area of research for well in materials science include the development of nanofiller reinforced polymer materials for additive manufacturing application. The dispersion of nanofiller in polymer matrix is a critical issue not only for control of processing but also for pre-defined properties. Quantitative analysis of extent of dispersion of nanofiller by measuring the rheological and surface characteristics of polymer nanocomposites has great technical importance for improving processing conditions, as well as for understanding the fundamental characteristics of materials at the nanoscale. The incorporation of nanofiller graphene into polymers is a promising approach to impart certain electrical and magnetic properties, mechanical reinforcement and high thermal conductivity to the resulting material. Rheological and surface properties of the poly(lactic) acid (PLA) based nanocomposites incorporating 0-9 wt.%. graphene nanoplates (GNPs) were investigated in the present work and a new strategy to tune such properties of PLA matrix by varying filler content is proposed.
The results of experimental studies of the compression process during the sintering under high pressure conditions of wurtzite boron nitride and diamond powders mixture of submicron sizes obtained by different technologies are given. It is determined that the compaction level at obtaining compositions depends on the dispersion and nature of the diamond component. Interaction of wurtzite boron nitride with diamond proceeds more intensively with diamonds of dynamic synthesis, but it is accompanied by their partial graphitization.
A novel technology for producing metal powders is presented, the distinctive feature of which are the conditions of forming of powder particles. In particular, under the proposed technology the melt is sucked bottom-up by the vacuum produced by the toroidal vortex of the discharged nucleus of high-pressure water flow in the two-layer cylindrical shell cavity, where it is being dispersed as metallic particles and carried over from the working medium to a special store. The so produced powders have a particular morphology and structure, increased specific surface area and microhardness.
The possibility of control of efficiency of different factors of high voltage electric discharge (HVED) impact on Ti – Al – С powders system for aimed synthesis of dispersion-hardening components is shown. Nanolaminate-composite Ti3AlC2 – TiC with hardness of HV5 = 7 GPa, obtained by consolidation of blend of 85 % Ti + 15 % Al initial composition after HVED with the use of multi-point electrode system has needle structure of Ti3AlC2 (a = 0.3068 nm, c = 1.844 nm) with size up to 10 μm, and TiC dispersion-hardening phase (a = c = 4.4331 nm) with particle size no more than 1 μm is situated between grains of Ti3AlC2. Dynamic strength of specimens depending on electrode system used during HVED treatment of blend variated in range from 160 to 620 MPa, Young modulus – from 13 to 22 GPa at deformation rate from 600 to 900 s–1. Material has high levels of heat resistance, relative change of mass is no more, than 0.001.
A complex approach to obtainment of titanium carbide hard metals, which consists of utilization of high density energy flows of high voltage electric discharges (HVED) for dispersion and activation of particles of powders mixture of 80 % Ti + 20 % Fe composition and synthesis of carbide phase and subsequent consolidation of obtained powders mixture by high density electric current with spark plasma sintering (SPS) method. Connection between specific cyclic energy of treatment of “kerosene – Ti + Fe powders mixture” disperse system and changes of dispersity, shape and phase composition of powders and physical and mechanical properties (hydrostatic density, hardness, thermal conductivity, wear resistance, dynamic strength) of materials consolidated from them is found. Tungstenless titanium carbide hard metals, which have high specific values of strength and wear resistance, hardness of which is higher than 82 HRA, and thermal conductivity of such materials is insignificantly lower than thermal conductivity of VK6 alloy, were obtained
Changes of dispersity, form factor and phase composition of powder mixtures of 75% Ti + 25% Al, 50% Ti + 50% Al, and 25% Ti + 75% Al mass compositions after treatment by high voltage electric discharge in kerosene are experimentally studied. Regularities of their dispersion and synthesis of TiC, AlTi3, AlTi, Al2Ti, Al3Ti, double carbide Ti3AlC, МАХ-phases Ti3AlC2 and Ti2AlC, Lonsdaleite are found.
In this article the mechanism of spreading of optical radiation in a Bragg fiber is considered. A mathematical model for analysis of a Bragg fiber viewed as a flat multilayered dielectric structure has been proposed. The method of geometrical optics of description of spreading the light is used. Formulas connecting the clad refractive index with fiber parameters are given. The light attenuation at its refraction in the multilayered clad and chromatic dispersion are calculated, as well as the dielectric loss of the clad material. The dispersion and the width of the waveband of Bragg fibers with different number of layers and low waveguide modes have been compared. Examples of fibers with different coefficient of dielectric material loss are included.