Functional State of Workers Data Analysis in the Labor Process

It is shown that the state of working people, determined using the WAM technique, (well-being, activity, mood) has statistically significant correlation with the results of instrumental measurements in terms of changes in the physiological state of the same workers. It is proposed to use the WAM test as an independent method for determining the functional state of workers. The purpose of this work was to determine the ratio of the functional state of workers according to the instrumental assessment, on the one hand, and self-assessment of their state, on the other

Hardness testing as a method to identify the highest-temperature combustion zone in transport fires

This article presents some results on the selection of the necessary micro-hardness tester for the purposes of research. In accordance with the objectives, namely the scientifically based choice of a hardness meter for the purposes of fire-technical examination and evaluation of its capabilities, aimed primarily at the possibility of identifying the most high-temperature combustion zone in fires in transport. The selection of a device for measuring microhardness was carried out in accordance with current methods for measuring microhardness, first of all for determination of microhardness for products based on metals and their alloys, as well as materials found in vehicles. The paper describes the main types of hardness testers and their applications. On the basis of the analysis programmable electronic small-sized hardness tester TEMP-4 was chosen. This device met all the requirements on the decision of set tasks of research connected with express researches both laboratory and industrial conditions, and the field at the decision of tasks of fire-technical examination directly on a place of ignition of the transport unit. Experimental results of nondestructive express measuring of various metal samples are described. Metal fasteners and supporting constructions are chosen as samples for research. The thermal effect on the test specimens was carried out in a thermostat chamber allowing for an impact heating rate. The results, testifying about change of microhardness of metal products as a result of influence of a high-temperature field are received

Comprehensive research method for explosive coal dust

The article briefly analyses the explosion and fire hazard properties of coal dust of different dispersions. It is emphasised that many experts working in the field of explosion protection and industrial safety pay insufficient attention to changes in the properties of the dust when reducing its dispersity. It is suggested to develop a new, complex methodology based on the dispersed composition of coal dust. The authors suggest to put methods of special sample preparation and dispersing of samples in two stages as a basis of the complex methodology. To do research with the help of thermal synchronous analysis of the smaller fractions, the authors propose to regrind the coal fraction obtained after the cone crusher in an analytical mill. To exclude adhesion of particles due to the process of static charges accumulation it is suggested to use impactless sieving machine of Retsch company which allows to take out the accumulated charges of static electricity. The coal dust fractions obtained after sieving were sent for granulometric analysis by a dynamic image processing method in CAMSIRE and by an optical microscopic method using a LEICA DM 4000 with image scope colour processing. A simultaneous thermal analysis was performed selectively for fractions smaller than 1000 μm. This was carried out with an STA 449 F3 and NETZSCH Proteus termal analysis application software. The authors consider that the obtained results allow to conclude that it is further expedient to carry out research work in this direction and will make it possible to develop recommendations aimed at prevention of coal dust aerosol explosions

Evaluation of energy-economic parameters of tractor with electrically driven power unit

The development of agro-industrial complex in modern conditionsneeds a large share of low traction class tractors. Manufacturers in their turn strive to fill the market with tractors with good consumer properties. The use of electric drive on tractors is a relatively new trend with many unresolved issues in various areasof this subject. In this paper the questions on prospects of using electric motors as a drive of tractor power unit are touched upon. Energy equipment and general preparedness for transition of tractors to such systems are considered. The question of comparison of basic parameters of electric and diesel engines, consisting in one power category, is considered. The methodology of estimation of energy-economic characteristics of a tractor with electric drive power unit in relation to a conventional tractor with dieselengine and argumentation of the given parameters are given. The usefulnessof the introduced index is shown, as well as the necessity of its use in order to evaluate the efficiency of engines of different types in a comparative analysis. This paper will be useful in the engineering and design field of knowledge related to the design and development of electric drive technologies for mobile machines

Impact of band-bending on the k-resolved electronic structure of Si-doped GaN

Band bending at semiconductor surfaces and interfaces is the key to applications ranging from classical transistors to topological quantum computing. A semiconductor particularly important for optical as well as microwave devices is GaN. What makes the material useful is not only its large bandgap but also that it can be heavily doped to become metallic. Here, we apply soft-x-ray angle-resolved photoelectron spectroscopy (ARPES) to metallic Si-doped GaN to explore the electron density and momentum-resolved band dispersions of the valence and conduction electrons varying through the surface band-bending region. We find an upward band bending, where the measured band occupation reduces toward the surface, as probed with low photon energies 1.4 keV, where the photoelectron mean free path exceeds the spatial extent of the band-bending region. Our quantitative analysis of the experimental data describes the potential variation in the band-bending region via self-consistent Poisson-Schrödinger equations. We put forward an insightful model to simulate the ARPES spectra from this region through summing up the contribution from all atomic layers, weighted by the photoelectron mean free path, under in-phase conditions achieved at particular values of the photoelectron out-of-plane momentum. The model adequately describes the peculiarities of the ARPES spectra caused by the surface band bending, including the photon-energy dependence of the apparent band occupation and Fermi-surface area, and allows accurate determination of the band-bending profile and values of the photoelectron mean free path. Finally, comparison of our data with supercell density functional theory calculations reveals the preferential location of Si atoms as substitutional for Ga, with the doped electrons entering the GaN conduction bands without formation of separate impurity states as would occur for Si interstitials. Our theoretical and experimental results resolve fundamental questions underpinning device performance of the GaN-based and other semiconductor materials in general and demonstrate a general methodology for quantitative studies of electron states in the band-bending region.ISSN:2643-156

From graphene oxide towards aminated graphene: facile synthesis, its structure and electronic properties

International audienceAbstract In this paper we present a facile method for the synthesis of aminated graphene derivative through simultaneous reduction and amination of graphene oxide via two-step liquid phase treatment with hydrobromic acid and ammonia solution in mild conditions. The amination degree of the obtained aminated reduced graphene oxide is of about 4 at.%, whereas C/O ratio is up to 8.8 as determined by means of X-ray photoelectron spectroscopy. The chemical reactivity of the introduced amine groups is further verified by successful test covalent bonding of the obtained aminated graphene with 3-Chlorobenzoyl chloride. The morphological features and electronic properties, namely conductivity, valence band structure and work function are studied as well, illustrating the influence of amine groups on graphene structure and physical properties. Particularly, the increase of the electrical conductivity, reduction of the work function value and tendency to form wrinkled and corrugated graphene layers are observed in the aminated graphene derivative compared to the pristine reduced graphene oxide. As obtained aminated graphene could be used for photovoltaic, biosensing and catalysis application as well as a starting material for further chemical modifications