National Repository of Grey Literature 7 records found  Search took 0.01 seconds. 
Evaluation of selected surface characteristics of CW004A copper disintegrated by PWJ
Lehocká, D. ; Klich, Jiří
Paper deals with copper CW004A surface characteristics evaluation after\ndisintegration by enhanced pulsating water jet. The main aim was identify and\ndescribe areas of pulsating water jet disintegration effects on material with using\ncircular nozzle diameter. 25 samples were disintegrated at change traverse speed\nv = 0.1 – 20 mm·s-1, for assessment of individual areas formation. Surface\ncharacteristics were evaluated based on surface roughness parameters Ra [μm],\nRz [μm], Rp [μm], Rv [μm], mass material removal Δm [mg.mm-1] and volume\nmaterial removal Vm [mm3]. Based on experimental investigation, three areas of\npulsating water jet effects on material were determined.
Visualisation and quantitative analysis of flat continuous water jet structure
Ščučka, Jiří ; Zeleňák, Michal ; Foldyna, Josef ; Lehocká, D. ; Votavová, H.
The results of an experiment focused on the visualisation and structural analysis of flat continuous high-speed water jet used in descaling process are presented in this paper. The aim of the work was to test the applicability of the shadowgraph technique, combined with image processing and analysis methods, to visualise the water jet structure and analyse its main quantitative parameters. Volume percentage of water and air in the water jet structure, size of droplets and water bunches and other parameters were measured on digital images taken at various distances from the nozzle outlet. Knowledge of the water jet structure below the nozzle can facilitate an optimal setting of technological conditions of the water jetting with respect to the maximum disintegration effect on treated material. The described methods can also provide important information for development of new nozzles or entire water jetting tools for disintegration of materials.
Erosion effects evaluation of pulsating water jet on brass EN 12164
Lehocká, D. ; Klich, Jiří ; Foldyna, Josef ; Hloch, Sergej ; Cárach, J.
The objective of this experiment is to verify an assumption that with decreasing value of feed rate, mass v material removal Δ of brass EN 12164 during cutting by pulsating water jet is increased, and to seek the mass erosion curve course depending on the change of feed rate v [mm·s-1]. The selected observed parameter was evaluated in two units of Δ [mg·s-1] and Δ [mg·mm-1]. Two mutually related experiments were carried out. In the pilot experiment, the curve originating at hydraulic power output of 15 kW was evaluated that was achieved in combination of nozzle diameter d [mm] and pressure p [MPa] - d/p [mm/MPa] = 1.0668/52; 1.3208/39; 1.6002/31. After the pilot experiment, another experiment followed in which a particular range of feed rate values v = 0.2 - 8 mm·s-1 was selected. This resulted in finding that different courses of erosion process exist for mass material removal expressed in the form of curve Δ [mg·s-1] and Δ [mg·mm-1], depending on feed rate v [mm·s-1].
Surface strengthening of a stainless steel using pulsating water jet technology - evaluation by means of microhardness measurements
Hloch, Sergej ; Ščučka, Jiří ; Lehocká, D. ; Simkulet, V.
Results of an experiment focused on surface strengthening of AISI 304 stainless steel using pulsating water jet technology is presented in the paper. The tested material was subjected to the action of pulsating water jet under changing technological conditions (water pressure, traverse speed, stand-off distance, and diameter of nozzle orifice). Microhardness measurements at various distances from the created traces were applied for assessing the material strengthening. Based on the results, it can be stated that the dynamic effects of pulsating water jet on the tested steel samples cause the material deformations leading to the formation of a zone of strengthened material along the disintegrated area.
Preliminary study using pulsating water jet for bone cement demolition
Hloch, Sergej ; Kloc, J. ; Foldyna, Josef ; Pude, F. ; Smolko, I. ; Zeleňák, Michal ; Sitek, Libor ; Hvizdoš, P. ; Monka, P. ; Monková, K. ; Kozak, D. ; Stoić, A. ; Sedmak, A. ; Milosevic, M. ; Lehocká, D. ; Mihalčinová, E.
The paper deals with the study of using the selective property of ultrasonic pulsating water jet for the disintegration of bone cement which creates the interface between femoral stem and trabecular bone tissue. For investigation, commercial bone cements were used. Bone cements were tested by nanoindentation in order to review their mechanical properties. A representative sample Palacos R+G was selected for disintegration of bone cement. Bone cements samples fixed between two plexiglasses were disintegrated using ultrasonic water jet and water jet generated by self-resonating nozzle at the pressure level of 20 MPa. Visualisation of bone cement demolition was provided with high speed 1 kHz cameras with two led pulsed sources. Potential were observed for using of pulsating water jet for bone cement demoliton during femoral stem extraction.
Preliminary analysis of volume material removal at bone cement disintegration by pulsating water jet
Lehocká, D. ; Hloch, S. ; Foldyna, Josef ; Monka, P. ; Monková, K. ; Brezíková, K.
The article deals with preliminary analysis of material removal during disintegration of bone cement. This article was created to show possibilities of pulsating water jet utilization in medicine. Experiments with pulsating water jet were done using two types of nozzles - flat and round. Traces in bone cement were measured by optical profilemeter MicroProf FRT. Results show that pulsating water jet will be possible focuses as a tool for medical purposes, but further detailed research is needed.
The Virtuosity of Violoncello Playing in the Work of David Popper
Lehocká Hošková, Dominika ; Hošek, Jiří (advisor) ; Hošek, Jiří (advisor) ; Chuchro, Josef (referee) ; Petráš, Miroslav (referee)
The main aim of my work is to introduce the personality of David Popper, as a virtuous cellist, teacher and composer.His virtuous technique gave the ground to modern cello playing. I pay a special attention to his etudes high School of Violoncello Playing and to his concertant pieces.

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3 Lehocká, D.
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