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A. Słowik

Application of evolutionary algorithm to design minimal phase digital filters with non-standard amplitude characteristics and finite bit word length

In this paper an application of evolutionary algorithm to design minimal phase digital filters with non-standard amplitude characteristics and with finite bit word length is presented. Four digital filters with infinite impulse response were designed using the proposed method. These digital filters possess: linearly falling characteristics, linearly growing characteristics, nonlinearly falling characteristics, and nonlinearly growing characteristics, and they are designed using bit words with an assumed length. This bit word length is connected with a processing register size. This register size depends on hardware possibilities where digital filter is to be implemented. In this paper, a modification of the mutation operator is introduced too. Due to this modification, better results were obtained in relation to the results obtained using the evolutionary algorithm with other mutation operators. The digital filters designed using the proposed method can be directly implemented in the hardware (DSP system) without any additional modifications.

Open access

J.A. Słowik, A. Drotlew and B. Piekarski

Abstract

The lifetime of guide grates in pusher furnaces for heat treatment could be increased by raising the flexibility of their structure through, for example, the replacement of straight ribs, parallel to the direction of grate movement, with more flexible segments. The deformability of grates with flexible segments arranged in two orientations, i.e. crosswise (perpendicular to the direction of compression) and lengthwise (parallel to the direction of compression), was examined. The compression process was simulated using SolidWorks Simulation program. Relevant regression equations were also derived describing the dependence of force inducing the grate deformation by 0.25 mm ‒ modulus of grate elasticity ‒ on the number of flexible segments in established orientations. These calculations were made in Statistica and Scilab programs. It has been demonstrated that, with the same number of segments, the crosswise orientation of flexible segments increases the grate structure flexibility in a more efficient way than the lengthwise orientation. It has also been proved that a crucial effect on the grate flexibility has only the quantity and orientation of segments (crosswise / lengthwise), while the exact position of segments changes the grate flexibility by less than 1%.

Open access

A. Drotlew, B. Piekarski and J. Słowik

Abstract

Various examples of the design of cast elements of the equipment used in furnaces for the heat treatment of machine parts are given. Shortcomings in their performance are indicated. Reasons for required stability of equipment are briefly discussed. Elements of equipment illustrate the possibilities of using a charge-carrying pallet with dimensions of 900×600×45 mm as a basis for multi-component technological equipment. Introducing additional elements, such as metal baskets, intermediate pallets or crossbars to the main pallet, it becomes possible to create different configurations of this equipment. The technological equipment presented and discussed here is offered to different plants which heat-treat a wide variety of produced parts. It was found that the reliability and durability of new designed equipment can be checked only during practical use. For large plants dealing with the heat treatment of bulk quantities of parts homogeneous or similar in shape is recommended to use the dedicated tooling.

Open access

J. Słowik, A. Drotlew and B. Piekarski

Abstract

The main aim of this study was to examine the compression-induced state of stress arising in castings of the guide grates during operation in pusher-type furnaces for heat treatment. The effect of grate compression is caused by its forced movement in the furnace. The introduction of flexible segments to the grate structure changes in a significant way the stress distribution, mainly by decreasing its value, and consequently considerably extends the lifetime of the grates. The stress distribution was examined in the grates with flexible segments arranged crosswise (normal to the direction of the grate compression) and lengthwise (following the direction of force). A regression equation was derived to describe the relationship between the stress level in a row of ribs in the grate and the number of flexible segments of a lengthwise orientation placed in this row. It was found that, regardless of the distribution of the flexible segments in a row, the stress values were similar in all the ribs included in this row, and in a given row of the ribs/flexible segments a similar state of stress prevailed, irrespective of the position of this row in the whole structure of the grate and of the number of the ribs/flexible segments introduced therein. Parts of the grate responsible for the stress transfer were indicated and also parts which play the role of an element bonding the structure.

Open access

Andrzej Koszewnik, Kamil Troc and Maciej Słowik

Abstract

The paper presents the design and practical implementation of PID controllers for a Stewart platform. The platform uses a resistance touch panel as a sensor and servo motors as actuators. The complete control system stabilizing the ball on the platform is realized with the Arduino microcontroller and the Matlab/Simulink software. Two processes required to acquire measurement signals from the touch panel in two perpendicular directions X and Y, are discussed. The first process includes the calibration of the touch panel, and the second process - the filtering of measurement signals with the low pass Butterworth filter. The obtained signals are used to design the algorithm of the ball stabilization by decoupling the global system into two local subsystems. The algorithm is implemented in a soft real time system. The parameters of both PID controllers (PIDx and PIDy) are tuned by the trial-error method and implemented in the microcontroller. Finally, the complete control system is tested at the laboratory stand.

Open access

E. Robens, A. Dąbrowski, E. Mendyk, J. Goworek, K. Skrzypiec, M. Drewniak, M. Dumańska-Słowik, W. Gac, R. Dobrowolski, S. Pasieczna-Patkowska, M. Huber, M. Iwan, K. Kurzydłowski, T. Płociński, J. Ryczkowski, Z. Rzączyńska and J. Sobczak

Investigation of surface properties of lunar regolith - Part IV

We investigated three lunar regolith powder samples from the Apollo missions. Apollo 11 and Apollo 12 samples come from lunar maria and Apollo 16 sample from a highland region. In the present paper we summarise in brief results of measurements using photoelectron spectroscopy (XPS), micro-Raman spectroscopy (RM), x-ray diffraction (XRD), x-ray fluorescence spectroscopy (XRF), temperature programmed reduction and oxidation (TPRO), thermogravimetry (TG), differential thermal analysis (DTA) and nitrogen adsorption. Parts of samples are visualised by means of scanning electron microscopy (SEM/EDX) and atomic force microscopy (AFM).