Mechanics
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ISSN 1734-8927
e-ISSN: 2300-7060
Issue Date
2007
Volume
Vol. 26
Number
No. 1
Description
Journal Volume
Mechanics
Vol. 26 (2007)
Projects
Pages
Articles
Optimization of rock disintegration based on acoustic background of drilling machine
(Wydawnictwa AGH, 2007) Kostúr, Karol; Futó, Jozef
The rotary drilling of rock is widespread technology in mining and in tunnelling. The paper describes the results of research by aim to find relationships between optimal drilling and sound signal of drilling machine. The optimisation criterion has been formulated as the minimisation of specific energy with maximal effective speed of drilling in process of the rock disintegration. The research in this field has been made on experimental drilling stand. Our monitoring system has measured following variables: pressing force of core drill, revolutions of drilling head, length of drilling, time, power, acoustic signals. For measurement of acoustic signals have been used very sensitively sound meter Mediator 2238. From this measurement have been processed acoustic spectrums. Then we are found relationships between optimal control of drilling and composition of acoustic spectrum. On base of experimental results, we can formulate the optimal control following: «To achieve the minimum difference between the equivalent sound level at the load and idle modes only at the representative frequency. The representative frequency dependences on type of the rock». New method based on these relationships enables the optimal control of drilling machine by using measured acoustic signals only.
Shape prediction during the free forming process of semi-finished products electrodynamically worked
(Wydawnictwa AGH, 2007) Kot, Andrzej; Bednarczyk, Józef
Possibility of free forming for semi-finished products and giving them demanded shapes without presence of forming dies distinguish the electrodynamic method in relation to standard technologies of metal plastic working, because there are no difficulties of using punch - die instrumentations. The article presents considerations referred to prediction possibilities of final shape of pipe and flat semi-finished products electrodynamically formed without using forming dies.
The use of coal in a theoretical gas turbine
(Wydawnictwa AGH, 2007) Kozaczka, Jarosław
In the paper has been presented the application of the on thermodynamic analyzes and ratings oriented modeling method of power systems. Simple combustion reaction with equilibrium on the products side was taken into account. Furthermore the modeling method of simple chemical reactions has been introduced, which is based on the so-called reaction intensity coefficient, analogous to the heat exchange process intensity in a membran apparatus. The presented discussion is an introductory investigation of the modeling of systems for the so-called clean solid fuels combustion systems, where additionally gasifying and absorption of carbon mono- and carbon dioxide are to be analyzed.
Cable - MR damper system motion in transients
(Wydawnictwa AGH, 2007) Sapiński, Bogdan; Snamina, Jacek
The paper addresses certain aspects concerning the interaction between a cable and a magnetorheological (MR) damper. An essential difference between the displacement of the point where the damper is attached and the displacements of other points remote from the damper has been observed during experiments. The results of experimental data imply non-steady state motion of the damper piston. Twice in one period of vibration, for a short time, the harmonic motion turns into the motion with almost constant velocity. After a few seconds, the damper can be blocked. During this time other points, remote from the damper, continue their harmonic motion. These phenomena have a significant meaning in cable - MR damper system motion and have to be taken into account while developing algorithms for MR damper control. A finite element model was formulated for the cable - MR damper system that describes the motion of the system with high precision. The influence of cable flexural stiffness in the neighbourhood of end clamps and damper handle were taken into account. Results of considerations are illustrated by numerical examples in which discussed effects are visible.
A new concept of a catalyst support for internal combustion engines
(Wydawnictwa AGH, 2007) Worsztynowicz, Barbara
Standard catalysis reactors are characterized by their channel structure. There are several channels per each cm2 of the core's surface. At the same time the length of each channel exceeds 100 times the cross section size. This causes splitting of the incoming to the reactor fumes into thousand pieces. Such a construction is characterized by a Iow mechanical endurance, high flow resistance, high inertia and an inclination for corking of particular channels. The core, according to the new conception, is made of: central partition connected continuously along the whole length of the side wall and a series of side and middle elements situated symmetrically on both sides of the middle partition. The height of the element walls is the height of the side walls and together they form a two side system of a network with crossing passage channels. Those channels are open on the axis inflow-outflow as well as in a direction perpendicular to the mid intersection. Both the middle and the side elements have internal spaces forming respectively middle and side compartments. Those compartments form a common two side open space for each pair of elements situated symmetrically to the middle partition. Each compartment has a connection with the channel network through a particular crack. The catalyser with core of the new construction is characterized by the good flow and mechanical properties. Preliminary experimental tests have shown that the phenomena occurring during the flow through the catalyser are with good agreement with the assumptions.