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Number of results: 43
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Abstract

The subject of the study was the No. 116/2 coal seam belonging to the Cracow Sandstone Series of the Upper Silesian Coal Basin. Reflectograms of the samples taking into account all the vitrinite group macerals present in the coal were recorded for Δ Ro close to the standard deviation and in the standard range. A careful analysis of vitrinite reflectograms reveals the presence of three or four clearly distinguished peaks. When assessing the rank of coal, only the main maximum, peak No. 4, was considered to be significant. Measurements of the average reflectance of collotelinite were made only on the vitrinite surfaces with a thickness of more than 1 mm. Only two maxima were revealed on detailed reflectograms. These maxima correlate with the peaks marked as No. 3 and 4 in the sample reflectograms taking into account all the vitrinite group macerals. The C daf content in the tested coal from the Janina coal mine is between 75.9 and 77.5 wt%, while for vitrain, it ranges from 71.1 to 75.5 wt%. This relationship is an exponential regression with a correlation coefficient of r = 0.95h and can be approximated by a linear correlation of r = 0.94. The correlation strength between the volatile matter content and the coefficient of average reflectance in the vitrinite of the tested coal was also examined. The statistically significant correlation is strong, which is expressed by the exponential correlation coefficient “r” being close to 0.99 and its linear approximation with the correlation coefficient r = 0.98. However, no correlation was found between the measured reflectance values and the GI coefficient calculated for the examined samples.
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Authors and Affiliations

Jacek Misiak
1
ORCID: ORCID

  1. AGH University of Kraków, Faculty of Geology, Geophysics and Environment Protection, Poland
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Abstract

Bragg scattering of waves propagating in a periodically disturbed substrate is widely applied in optics and micro-acoustic systems. Here, it is studied for Rayleigh waves propagating on a periodically grooved elastic substrate. Practically applied groove depth in the Bragg grating reflectors does not exceed a few percent of the Rayleigh wavelength. Here, the analysis is carried out for periodic grooves of larger depth by applying the elastic plate model for the groove walls. The computed results show that the surface wave existence and reflection depends strongly on both the groove depth and period, and that there are limited domains of both for practical applications, primarily in comb transducers of surface waves.

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Authors and Affiliations

Eugeniusz Danicki
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Abstract

Comb transducers are applied in ultrasonic testing for generation of Rayleigh or Lamb waves by scattering of the incident bulk waves onto surface waves at the periodic comb-substrate interface. Hence the transduction efficiency, although rarely discussed in literature, is an important factor for applications determining the quality of the measured ultrasonic signals. This paper presents the full-wave theory of comb transducers concluded by evaluation of their efficiency for a couple of examples of standard and certain novel configurations.

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Authors and Affiliations

Eugeniusz Danicki
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Abstract

Reflecting structures placed over the stage in auditoria and concert halls should provide sound reflection in a way that enhances sound emission from the stage without causing acoustic defects in the interior. Model studies conducted by the authors were used to determine the relative level of sound reflection by reflecting structures as a function of frequency for a number of geometric configurations and materials. Analysis of the results allowed drawing conclusions about the effect of modifications of the ceiling over the reflecting panels on the quality of the sound reflected from them. It was shown that modification of the ceiling over the reflecting panels by employing highly sound absorbing materials significantly improved the characteristics of the reflected sound. Also, certain configurations of elements located in the space under the ceiling should be avoided, as the experiments indicated the occurrence of adverse acoustic effects.

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Authors and Affiliations

Tadeusz Kamisiński
Agata Szeląg
Jarosław Rubacha
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Abstract

The paper presents the verification of a solution to the narrow sound frequency range problem of flat reflective panels. The analytical, numerical and experimental studies concerned flat panels, panels with curved edges and also semicircular elements. There were compared the characteristics of sound reflected from the studied elements in order to verify which panel will provide effective sound reflection and also scattering in the required band of higher frequencies, i.e. above the upper limit frequency. Based on the conducted analyzes, it was found that among some presented solutions to narrow sound frequency range problem, the array composed of panels with curved edges is the most preferred one. Nevertheless, its reflection characteristic does not meet all of the requirements, therefore, it is necessary to search for another solution of canopy which is effective over a wide frequency range.
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Authors and Affiliations

Agata Szeląg
Tadeusz Kamisiński
Mirosława Lewińska
Jarosław Rubacha
Adam Pilch
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Abstract

The paper deals with analysis of recognition of surface quality with reflective structures. Such surfaces are common in metallic materials cut using a saw or polished. There are no easy methods to identify such elements after machining. This issue is crucial in the industry for quality control as recognition of the elements, for instance after failure, allows for a detailed study of their manufacturing process. Firstly, six cuboid steel elements were obtained from a larger beam with a circular saw. Then, the bidirectional reflection distribution function (BRDF) was obtained for each element 3 times. The BRDF profiles were used in custom recognition software based on the K-nearest neighbors algorithm. In total, 140 variants of the classifier were tested and analyzed. Additionally, each variant was solved 200 times with different splits of the dataset. The results showed a high multiclass accuracy in all considered variants of the algorithm, with multiple variants achieving 100% accuracy. This level of performance was attained with only 1 to 2 training samples per class. Its low numerical complexity, easy experimental procedure, and “one-shot” nature allow for fast recognition, which is crucial in industrial applications.
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Authors and Affiliations

Adam Ciszkiewicz
1
Janusz Jaglarz
2
Tadeusz Uhl
3

  1. Faculty of Mechanical Engineering, Cracow University of Technology, Al. Jana Pawła II 37, 31-864 Cracow, Poland
  2. Faculty of Material Engineering, Cracow University of Technology, Al. Jana Pawła II 37, 31-864 Cracow, Poland
  3. Department of Robotics and Mechatronics, Faculty of Mechanical Engineering and Robotics, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059, Cracow, Poland
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Abstract

The author, as a former pupil of the title figure of this paper, and as a leading his cooperator in numerous creative works, recalls memoires and presents an analysis of the personality of late professor of architectute, J. Tadeusz Gawłowski. The paper represents both – objective and official features of chronicle, hence also introduces readers into more personal secrets of the outstanding architect: creator, scholar and academic teacher – being simultaneously a picturesque and friendly person. He was connected mainly with Kraków University of Technology, but sharing also his activity in order to fulfill needs of three other, important academic schools.

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Authors and Affiliations

Maciej Złowodzki
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Abstract

The present article investigates theoretically the refection and transmission through a lossless dielectric slab embedded between two semi−infinite left−handed materials (LHMs) in which the electric permittivity and magnetic permeability are simultaneously negative. The LHM is assumed to be dispersive according to Lorentz as well as Drude medium model. The reflection and transmission coefficients are studied with the angle of incidence, frequency and slab thickness. The effect of the damping frequency is also investigated. It is found that the damping frequency has an insignificant effect on reflected, transmitted and loss powers. Band pass filter is one of the possible applications of the proposed structure.

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Authors and Affiliations

S.A. Taya
D.M. El-Amassi
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Abstract

This article presents an efficient method of modelling acoustic phenomena for real-time applications such as computer games. Simplified models of reflections, transmission, and medium attenuation are described along with assessments conducted by a professional sound designer. The article introduces representation of sound phenomena using digital filters for further digital audio processing.
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Authors and Affiliations

Bartłomiej Miga
Bartosz Ziółko
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Abstract

The paper presents the new solution to a road acoustic screen consisting of elements which are highly diffusing and simultaneously resistant to weathering, but also characterised by a sound absorption. There is described the comprehensive research of such the road acoustic screen with absorbing and diffusing surface. The study includes screen’s resistance to wind load and snow removal, impact tests and mea- surements of some acoustic parameters
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Authors and Affiliations

Tadeusz Kamisiński
Roman Kinasz
Agata Szeląg
Jarosław Rubacha
Adam Pilch
Artur Flach
Katarzyna Baruch
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Abstract

Ray tracing simulation of sound field in rooms is a common tool in room acoustic design for predicting impulse response. There are numerous commercial engineering tools utilising ray tracing simulation. A specific problem in the simulation is the modelling of diffuse reflections when contribution of individual surface is prevailing. The paper introduces modelling of scattering which is interesting when the whole impulse response of a room is not a goal but contribution of certain surface. The main goal of the project is to shape directivity characteristics of scattered reflection. Also, an innovative approach is suggested for converting the energy histogram information obtained by ray tracing into an “equivalent impulse response”. The proposed algorithm is tested by comparing the results with measurements in a real sound field, realised in a scaled model where a diffusing surface is hardware-implemented.

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Authors and Affiliations

Srđan Bojičić
Dragana Šumarac-Pavlović
Miomir Mijić
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Abstract

The article represents research into poetry written during the Revolution of Dignity (2014). Such artistic texts are analyzed as a kind of phenomenon of contemporary literature. These are the poems of famous authors or even amateurs, united by a common sacred code. They appeal to the patterns and archetypes of the collective consciousness of Ukrainians. In the poetry of Euromaidan the researcher underlines two types of sacralization, which can be conditionally called masculine and feminine (paternal and maternal). The masculine type of this process realizes a symbolic projection of the figure of Jesus Christ. This symbol emphasizes the determination of the act, active attitude, the idea of fighting for the truth, as well as the willingness to sacrifice their own lives for the common good. The feminine version of the proces of sacralization is the Virgin Mary. This image appeals not to the heroic act, but to its emotional reflection, more specifically – the suffering, pain, traumatic experience of the victim. It corresponds to the archetypal image of the Mother of God, the Suffering Mother, who sacrifices her own son to death and cries for him later. The embodiment of the Christian sacrum in the poetry of the Maidan testifies to the fidelity to both European and Ukrainian traditions.
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Authors and Affiliations

Jarosław Poliszczuk
1
ORCID: ORCID

  1. Uniwersytet im. Adama Mickiewicza w Poznaniu
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Abstract

We report on the absorption properties of polarization-insensitive transmissive and reflective metamaterial absorbers based on two planar aluminium periodic structures and SU-8 epoxy resist. These absorbers were investigated using numerical simulation and experimental methods in the terahertz range (below 2 THz). SU-8 is a very promising organic material for dielectric layers in planar metamaterials, because its application simplifies the process of fabricating these structures and significantly reduces the fabrication time. The experimental absorption of the metamaterial absorbers has narrowband characteristics that were consistent with the numerical simulations. Power flow analysis in the transmissive metamaterial unit cell shows that the absorption in the terahertz range occurs primarily in the SU-8 layer of the absorber.

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Authors and Affiliations

B. Grześkiewicz
A. Sierakowski
J. Marczewski
N. Pałka
E. Wolarz
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Abstract

The paper presents the concept of a fully planar treeshaped antenna with quasi-fractal geometry. The shape of the proposed radiator is based on a multi-resonant structure. Developed planar tree has symmetrical branches with different length and is fed by a coplanar waveguide (CPW) with modified edge of the ground plane. The antenna of size 29 mm x25 mm has been designed on Taconic - RF-35 substrate (r = 3.5, tg= 0.0018, h = 0.762 mm). The paper shows simulated and measured characteristics of return loss, as well as measured radiation patterns. The proposed antenna could be a good candidate for broadband applications (for instance: wideband imaging for medical application and weather monitoring radars in satellite communication etc.)

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Authors and Affiliations

Małgorzata Malinowska
Marek Kitliński
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Abstract

Studies on the quality of bituminous coal are mainly focused on physico-chemical analysis, examining the ash content, sulphur content, volatile matter content, moisture content, and the Net Calorific Value of coal. Until now, the above mentioned parameters form the basis of the Polish Standard PN-82/87002, on the basis of which individual types of bituminous coal are determined. In addition, an elemental analysis, providing information about the content of primary elements in the organic matter of solids, i.e. coal, hydrogen, nitrogen, oxygen, and sulphur, is carried out for the selected samples. This issue has been studied by many authors, which undoubtedly provide invaluable knowledge due to the huge amount of data, but, as the authors themselves indicate, the knowledge of the petrography of coal, coking properties (Probierz et al. 2012) and finally the coke obtained from individual coal types (based on tests carried out using the Karbotest installation or the so-called „box tests” performed in the coke oven battery) is still very limited. The article discusses the impact of petrographic composition on the quality of metallurgical coke. The analysis was performed using samples of coking coal from the following mines: Pniówek, Zofiówka, Borynia, and Krupiński. The mentioned coal types are used to produce coke mixtures used for the production of coke in the Przyjaźń and Radlin coking plants. Based on the rank of coal and physicochemical parameters, the mentioned coal types were classified according to the Polish classification and the UN/ECE International Classification of In-Seam Coals (UN/ECE 1995). The prediction of thermomechanical properties of coke (CSR and CRI) performed according to the original CCP method were compared with the results obtained using the classical method of Nippon Steel Corporation.

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Authors and Affiliations

Iwona Jelonek
Zbigniew Jelonek
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Abstract

Being reflective is one of the most paramount features that EFL (English as a Foreign Language) teachers need to be equipped with in the post-method era for their professional growth and development. The present study aimed to explore reflective teaching from a multi-dimensional perspective in terms of a) determinants that simulates teachers to reflect, b) consequences that teachers experience as a result of their reflective teaching, and c) obstacles that may arise and preclude teachers from reflective teaching. Qualitative data collection method was employed to gather data from 10 EFL teachers triangulating semi-structured interviews, diaries, journal, and observation. Data analysis via MAXQDA led to the emergence of three models for each dimension of the study. The results revealed that teachers not only reflect to respond to a problem, but also they reflect to diminish some negative factors like stress or anxiety on the part of both learners and themselves as well as improving, enhancing, or mending something in teaching or learning. The codes of determinants were also conceptualized into three broad categories of reflection-in-action, reflection-on-action, and reflection-for-action with the reflection-for-action used more frequently by the teachers. In the case of consequences, the codes were classified into two categories of internal and external consequences. It was also concluded that some of the consequences reinforce the reflective teaching and play the role of determinants motivating teachers to reflect again. Regarding the obstacles, after categorizing the codes into external and internal obstacles, it was observed that external factors are more robust.

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Authors and Affiliations

Farzaneh Tabassi
Afsaneh Ghanizadeh
Parinaz Gharooni Beigi
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Abstract

The given article explores the topic of the content and poetic specificity of Ukrainian Christmas carols published in Pochayiv Bohohlasnyk (1790/1791), the republication of which was carried out thanks to the Ukrainian scholar Yuriy Medvedyk. Ivan Franko’s ideas as to the context of Ukrainian carols from Bohohlasnyk seem rather important. The author of the paper believes that I. Franko was right in his recommendations “to look for mixtures of the influences of western and eastern traditions” in the texts of such works, paying special attention to the Polish impact. The given article also deals with the division of these Christmas songs into the naïve and the reflection related, as well as scholars’ analysis of the language of these carols (that was mainly one of the reasons why carols were popular among ordinary people). One can vividly see that Christmas carols are based on a national component that can be traced from “transferring the Bethlehem scenario into Ukraine and its rural world of customs, circumstances, feelings and communication” (Mykhaylo Vozniak). Consequently, the carols have acquired a high literary value. As proof, t certain carols appeared in the folklore collections of Volodymyr Hnatyuk, Pavlo Chubynskyy and Klyment Kvitka, as well as present day editions of Christmas carols, Epiphany songs and literary works. The given paper also includes crucial folklore records of Christmas carols from Pochayiv Bohohlasnyk compiled by students of the Ivan Franko National University in Lviv.
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Bibliography


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Authors and Affiliations

Василь Івашків
1
ORCID: ORCID

  1. Львівський національний університет імені Івана Франка
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Abstract

The reflection coefficient of the open end belongs among the essential parameters in the physical description of a flue organ pipe. It leads directly to practical topics such as the pipe scaling. In this article, sound propagation is investigated inside an organ pipe with the most intense mean flow that is achievable under musically relevant conditions. A theoretical model is tested against the experimental data to obtain a suitable formula for the reflection coefficient when a non-negligible flow through the open end is considered. The velocity profile is examined by means of particle image velocimetry. A fully developed turbulent profile is found and interactions of the acoustic boundary layer with the turbulent internal flow are discussed. A higher value of the end correction than expected from the classical result of Levine and Schwinger is found, but this feature shall be associated with the pipe wall thickness rather than the mean flow effects.
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Bibliography

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Authors and Affiliations

Viktor Hruška
1
Pavel Dlask
1

  1. Academy of Performing Arts in Prague, Musical Acoustics Research Centre, Prague, Czech Republic
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Abstract

In this study a metal clad waveguide sensor with a metamaterial guiding layer is analyzed. Sensitivity of the proposed sensor is derived using dispersion and Fresenal’s equations for waveguiding mode and reflection mode. While efficiently analyzing and comparing the results with the existing one, some interesting findings are achieved. It is observed that the proposed sensor shows larger cover layer sensitivity and larger adlayer sensitivity compared to the dielectric guiding layer sensor due to adsorbtive properties of metamaterial. Henceforth, it concludes that the proposed sensor shows sensitivity improvement over a dielectric guiding layer sensor.

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Authors and Affiliations

A. Upadhyay
Y.K. Prajapati
R. Tripathi
V. Singh
J.P. Saini
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Abstract

Results of the studies of optical properties of anti-reflective glasses with various texturization patterns, which were used as a coating for crystalline silicon solar cells, are presented. It was found that glass samples sorted by their optical transmittance demonstrated the same order as when sorted by their solar-cell short-circuit current enhancement parameter. The value of the latter depended on the parameters of texturization, such as the surface density of inclusions and their profile, and the depth of etching pits. A 2% relative increase of the solar cell efficiency was obtained for the best glass sample for null degree angle of incidence, proving enhanced light trapping properties of the studied glass.

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Authors and Affiliations

M. Pociask-Bialy
K.D. Mynbaev
M. Kaczmarzyk
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Abstract

This paper presents a simulation study of the simultaneous reconstruction of the non-smooth strain distribution of an optical fiber Bragg grating and its temperature, which is based on the reflection spectrum of the reflected beam of the grating. The transition matrix method was used to model the reflection spectrum of the grating, and the nonlinear Nelder- Mead optimization method was used to simultaneously reconstruct the strain distribution along the grating and its temperature. The results of simulations of simultaneous reconstruction of the strain profile and temperature indicate good accord with the strain profiles and temperature set. The reconstruction errors of the strain profiles are less than 1.2 percent and the temperature change errors are less than 0.2 percent, with a noise level of 5 percent.
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Authors and Affiliations

Małgorzata Detka
1
Cezary Kaczmarek
2

  1. Faculty of Electrical Engineering, Automatic Control and Computer Science, Kielce University of Technology, Poland
  2. Faculty of Electrical Engineering and ComputerScience, Lublin University of Technology, Poland
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Abstract

This work concerns the study of the coatings for the ultrasound frequency range as a quasi one-dimensional phononic crystal structure protecting a sea object against high resolution active sonar in the frequency range most commonly found for this type of equipment. The topology of the examined structure was optimized to obtain a band gap in the 2.2-2.3 MHz frequency band. For this purpose, a genetic algorithm was used, which allows for optimal distribution of individual elements of the ultrasound multilayer composite. By optimal distribution is meant to achieve a structure that will allow minimal reflectance in a given frequency range without height reflectance peaks with a small half width. Analysis of the wave propagation was made using the Transfer Matrix Method (TMM). As part of the research, 15 and 20-layer structures with reflectance at the level of 0.23% and 0.18%, respectively, were obtained. Increasing the number of layers in the analyzed structures resulted in finding such a distribution in which a narrow band of low reflectance was obtained, such distributions could also be used as bandpass filters. The use of a genetic algorithm for designing allows to obtain modern coatings, the characteristics of which result from the structure.
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Authors and Affiliations

S. Garus
1
ORCID: ORCID
W. Sochacki
1
ORCID: ORCID
J. Garus
1
ORCID: ORCID
A.V. Sandu
2
ORCID: ORCID

  1. Czestochowa University of Technology, Department of Mechanics and Fundamentals of Machinery Design, Faculty of Mechanical Engineering and Computer Science, 73 Dąbrowskiego Str., 42-201 Częstochowa, Poland
  2. Gheorghe Asachi Technical University of Iasi, Faculty of Materials Science and Engineering, Blv d. D. Mangeron 71, 700050 lasi, Romania
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Abstract

The author of the article analyzes the first literary attempts to reflect the experience of Russia’s full‑scale war against Ukraine. The main attention is paid to the problem of the traumatic experience of the war, based on the first feelings of shock and its consequences. The researcher considers three books (anthologies of poems, essays and diaries Poetry without Shelter, The War‑2022 and Oksana Zabuzhko’s essay A Long Journey), which were published during the first year of the war. These are dissimilar books, but they represent one problem from different points of view. The texts are those of contemporary Ukrainian authors who survived the traumatic experience of the Russian invasion in February 2022 in different places and under different circumstances. The author of the article interprets these works as a cultural tool in the process of mastering the state of shock, and later – as a mechanism for the verbal representation of the trauma itself.
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Authors and Affiliations

Oksana Pukhonska
1

  1. The National University of Ostroh Academy

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