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Cristian Costa, Lucian Lupu and Eduard Edelhauser

References [1]. Barlow A., Clarke R., Johnson N., Seabourne B., Thomas D. and Gal J., Effect of massage of the hamstring muscle group on performance of the sit and reach test, Br Journal of Sports Medicine, no.38, pp. 349-351, (2004). [2]. Bealko S. B., Alexander D.W., Chasko L. L. and Grayson R L, Mine rescue training facility inventory – compendium of ideas to improve, 2009. [3]. Conti R. S., Chasko L. L. and Stowinsky L. D., Mine rescue training simulations and technology, Proceedings of the Fifth Annual Conference of the International

Open access

Violeta Cristina Dumitru

International Conference on Robotics and Automation,, pg. 1573-1579, 1997. 4. Reynaerts, D., Peirs, J., Van Brussel, H., “Shape memory microactuation for a gastro-intestinal intervention system,” Sensors and Actuators, A: Physical, vol. 77, pp. 157, 1999. 5 Guthart, G., Salisbury, K., „The intuitive tele-surgery; overview and application” IEEE International Conference on Robotics and Automation, pp. 618-621, 2000. 6. Dumitru V., PHD thesis: Poli-articulated mechanical system used in medical domain, Craiova, 2011. 7 Dumitru V., Modular System for

Open access

Oleg Klyus and O. Bezyukov

Abstract

The paper presents the laboratory test results determining physical parameters of fuel mixture made up of petroleum diesel oil, rapeseed oil methyl esters (up to 20%) and water (up to 2.5%). The obtained parameters prove that adding bio-components (rapeseed oil methyl esters) and water to fuel does not result in deterioration of their physical and chemical properties and are comparable to base fuel parameters, namely petroleum diesel oil. The mixture was a subject of bench testing with the use of a self-ignition engine by means of pre-catalytic fuel treatment. The treatment process consisted in fuel - catalytically active material direct contact on the atomizer body. At the comparable operational parameters for the engine, the obtained exhaust gases opacity was lower up to 60% due to the preliminary fuel mixture treatment in relation to the factory-made fuel injection system using petroleum diesel oil.

Open access

Magdalena Tutak

Abstract

One of the most common and most dangerous hazards in underground coal mines is fire hazard. Mine fires can be exogenous or endogenous in nature. In the case of the former, a particular hazard is posed by methane fires that occur in dog headings and longwalls. Endogenous and exogenous fires are large hazard for working crew in mining headings and cause economics losses for mining plants. Mine fires result in emission of harmful chemical products and have a crucial impact on the physical parameters of the airflow. The subject of the article concerns the analysis of the consequences of methane fires in dog headings. These consequences were identified by means of model-based tests. For this purpose, a model was developed and boundary conditions were adopted to reflect the actual layout of the headings and the condition of the atmosphere in the area under analysis. The objective of the test was to determine the effects of methane fires on the chemical composition of the atmosphere and the physical parameters of the gas mixture generated in the process. The results obtained clearly indicate that fires have a significant impact on the above-mentioned values. The paper presents the distributions for the physical parameters of the resulting gas mixture and the concentration of fire gases. Moreover, it shows the distributions of temperature and oxygen concentration levels in the headings under analysis. The methodology developed for the application of model-based tests to analyse fire events in mine headings represents a new approach to the problem of investigating the consequences of such fires. It is also suitable for variant analyses of the processes related to the ventilation of underground mine workings as well as for analyses of emergency states. Model-based tests should support the assessment of the methane hazard levels and, subsequently, lead to an improvement of work safety in mines.

Open access

Aneta Grodzicka and Jan Szlązak

Abstract

The authors of the current study undertook the subject of the analysis features of the mining rescuer as a member of the ranks of the rescue, with particular emphasis on the following parameters: heart rate, body weight, height, BMI, age and seniority in the mining and rescue. This publication concerns the analysis of the test results of these characteristics rescuer as a potential member of the ranks of the rescue, taking into account its risk appetite, stress resistance, attitude towards life, the role of the team, teamwork, attitude to work, motivation to work and physical fitness.

Open access

Zdenko Tkáč, Marek Halenár and Ján Kosiba

for the testing of hydraulic pumps and liquids. Tribology in Industry, 40(1). pp. 149-155. Tóth, F., Rusnák, J., Kadnár, M. and Váliková, V. (2014). Study of tribological properties of chosen types of environmentally friendly oils in combined friction conditions. Journal of Central European Agriculture, 15(1) pp. 185-192. Tulík, J., Hujo, Ľ., Stančík, B. and Ševčík, P. (2013). Research of new ecological synthetic oil-based fluid. Journal of Central European Agriculture, 14(4), pp. 1384-1393. Will, D., Gebhardt, N

Open access

Dawid Szurgacz and Jarosław Brodny

., Brodny, J. (2017). An innovative system to test components of mining machinery control hydraulics. SGEM 2017, Conference proceedings, 17(13), pp. 47-54. Tutak, M., Brodny, J. (2017). Determination of Particular Endogenous Fires Hazard Zones in Goaf with Caving of Longwall. IOP Conf. Series: Earth and Environmental Science 95 (2017). Tutak, M. (2017a). Analysis of varying levels of methane emissions from coal mines in Poland. SGEM2017 Vienna GREEN Conference Proceedings, 17(43), pp. 301-308. Tutak, M. (2017b). Assessment

Open access

Stefan Berczyński, Daniel Grochała and Zenon Grządziel

Abstract

The article deals with computer-based modeling of burnishing a surface previously milled with a spherical cutter. This method of milling leaves traces, mainly asperities caused by the cutting crossfeed and cutter diameter. The burnishing process - surface plastic treatment - is accompanied by phenomena that take place right in the burnishing ball-milled surface contact zone. The authors present the method for preparing a finite element model and the methodology of tests for the assessment of height parameters of a surface geometrical structure (SGS). In the physical model the workpieces had a cuboidal shape and these dimensions: (width × height × length) 2×1×4.5 mm. As in the process of burnishing a cuboidal workpiece is affected by plastic deformations, the nonlinearities of the milled item were taken into account. The physical model of the process assumed that the burnishing ball would be rolled perpendicularly to milling cutter linear traces. The model tests included the application of three different burnishing forces: 250 N, 500 N and 1000 N. The process modeling featured the contact and pressing of a ball into the workpiece surface till the desired force was attained, then the burnishing ball was rolled along the surface section of 2 mm, and the burnishing force was gradually reduced till the ball left the contact zone. While rolling, the burnishing ball turned by a 23° angle. The cumulative diagrams depict plastic deformations of the modeled surfaces after milling and burnishing with defined force values. The roughness of idealized milled surface was calculated for the physical model under consideration, i.e. in an elementary section between profile peaks spaced at intervals of crossfeed passes, where the milling feed fwm = 0.5 mm. Also, asperities after burnishing were calculated for the same section. The differences of the obtained values fall below 20% of mean values recorded during empirical experiments. The adopted simplification in after-milling SGS modeling enables substantial acceleration of the computing process. There is a visible reduction of the Ra parameter value for milled and burnished surfaces as the burnishing force rises. The tests determined an optimal burnishing force at a level of 500 N (lowest Ra = 0.24 μm). Further increase in the value of burnishing force turned out not to affect the surface roughness, which is consistent with the results obtained from experimental studies.

Open access

Juraj Ružbarský and Witold Biały

Abstract

The article deals with the formation and spread of cracks from thermal fatigue in metallic forms. For a detailed examination of the problem, it is necessary to describe the thermal side of the process and the mechanism of mechanical stressing of the material. For the heating of the material is valid where the thermal diffusivity of the material is exercised by the decision method. The stress of the material by heating from the die casting metal depends mainly on the physical properties of the material when the calculated stress does not exceed the yield point. Also, with the help of dislocations write the life to the origin of the cracks in the cycles eventually the share of this lifetime on the total lifetime in dependence on the mechanical and physical properties of the material. During operation tests the occurrence of the cracks on the mold surface was initiated by the inclusion or concentration of stress in the knurling effect of fine grooves after grinding. Other cracks occurred in the undersurface layer and their direction was statistically accidental.

Open access

Marek Madajewski and Zbigniew Nowakowski

Abstract

This paper presents analysis of flank wear influence on forces in orthogonal turning of 42CrMo4 steel and evaluates capacity of finite element model to provide such force values. Data about magnitude of feed and cutting force were obtained from measurements with force tensiometer in experimental test as well as from finite element analysis of chip formation process in ABAQUS/Explicit software. For studies an insert with complex rake face was selected and flank wear was simulated by grinding operation on its flank face. The aim of grinding inset surface was to obtain even flat wear along cutting edge, which after the measurement could be modeled with CAD program and applied in FE analysis for selected range of wear width. By comparing both sets of force values as function of flank wear in given cutting conditions FEA model was validated and it was established that it can be applied to analyze other physical aspects of machining. Force analysis found that progression of wear causes increase in cutting force magnitude and steep boost to feed force magnitude. Analysis of Fc/Ff force ratio revealed that flank wear has significant impact on resultant force in orthogonal cutting and magnitude of this force components in cutting and feed direction. Surge in force values can result in transfer of substantial loads to machine-tool interface.