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The fiftieth anniversary of ,,Wiadomości Numizmatyczne"

Stanisław Suchodolski

Wiadomości Numizmatyczne | 2006 | Rok L | Zeszyt 2 (182) | 121-126

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Authors and Affiliations

Stanisław Suchodolski

Steganography in Audio Files – COTS Software Analysis

Piotr Marszałek Piotr Bilski

International Journal of Electronics and Telecommunications | 2023 | vol. 69 | No 1 | 121-126 | DOI: 10.24425/ijet.2023.144340

Keywords steganography audio information hiding steganalysis encryption compression cybersecurity cyberspace embedding information security privacy signal plane non-signal plane

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Abstract

The paper presents the analysis of the Commercial Off-The-Shelf (COTS) software regarding the ability to be used in audio steganography techniques. Such methods are a relatively new tool for hiding and transmitting crucial information, also being used by hackers. In the following work, the publicly available software dedicated to audio steganography is examined. The aim was to provide the general operating model of the information processing in the steganographic effort. The embedding method was analyzed for each application, providing interesting insights and allowing classifying the methods. The results prove that it is possible to detect the hidden message within the specific audio file and identify the technique that was used to create it. This may be exploited further during the hacking attack detection and prevention.

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Authors and Affiliations

Piotr Marszałek

Piotr Bilski

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Doctoral School, Warsaw University of Technology, Warsaw, Poland
Warsaw University of Technology, Warsaw, Poland

The influence of Iron and Aluminium Powder Pressing on the Course of Shrinkage and Properties of the Fe40Al Phase Obtained by Reaction Sintering

M. Berendt-Marchel D. Siemiaszko

Archives of Metallurgy and Materials | 2022 | vol. 67 | No 1 | 121-126 | DOI: 10.24425/amm.2022.137480

Keywords intermetallic powder metallurgy reaction sintering mechanical properties

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Abstract

The effect of the compaction rate on the structure, microstructure and properties of Fe-Al sinters obtained during the SHS reaction is presented in this paper. It was found that increasing the uniaxial pressing pressure led to the increase of the contact area between iron and aluminium particles, which improved the conduction and lowered heat losses during the self-propagating high-temperature synthesis (SHS) reaction and thus result with a sintered material with an improved phase homogeneity. On the other hand, an increase in the pressing pressure causes air be trapped in the pores and later on reacts with iron and aluminium to form oxides. In this work, the shrinkage course was analysed at six different pressing pressures: 50, 100, 150, 200, 300 and 400 MPa. The green compacts were then subjected to the PAIS process (pressure-assisted induction sintering) at a temperature of 1000°C under a load of 100 kN for 5 min. Such prepared samples were subjected to density, porosity, and microhardness (HV0.1) measurements. X-ray diffraction phase analysis and SEM observations were performed together with EDS chemical composition measurements. For studied chemical composition of the samples and sample geometry, 200 MPa compacting pressure was found to be optimal in order to obtain the best sample homogeneity.

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Authors and Affiliations

M. Berendt-Marchel

D. Siemiaszko

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Military University of Technology, 2 Gen. Sylwestra Kaliskiego Str., 00-908 Warszawa, Poland

Design of Sparse FIR Filters with Low Group Delay

Jacek Konopacki

International Journal of Electronics and Telecommunications | 2021 | vol. 67 | No 1 | 121-126 | DOI: 10.24425/ijet.2021.135953

Keywords digital filters FIR filters design sparse filters reduced group delay filters

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Abstract

The aim of the work is to present the method for designing sparse FIR filters with very low group delay and approximately linear-phase in the passband. Significant reduction of the group delay, e.g. several times in relation to the linear phase filter, may cause the occurrence of undesirable overshoot in the magnitude frequency response. The method proposed in this work consists of two stages. In the first stage, FIR filter with low group delay is designed using minimax constrained optimization that provides overshoot elimination. In the second stage, the same process is applied iteratively to reach sparse solution. Design examples demonstrate the effectiveness of the proposed method.

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Authors and Affiliations

Jacek Konopacki

Faculty of Automatic Control, Electronics and Computer Sciences, Silesian University of Technology

Influence of Tungsten on the Structure and Properties of Ductile Iron Containing 0.8% Cu

D. Myszka Justyna Kasińska A. Penkul

Archives of Foundry Engineering | 2021 | vo. 21 | No 4 | 121-126 | DOI: 10.24425/afe.2021.139760

Keywords Metallography Mechanical properties Tungsten Cast iron

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Abstract

The possibilities of producing ductile cast iron with the addition of 1 ÷ 3% of tungsten are presented. Tungsten from waste chips from mechanical processing was introduced into the liquid cast iron in the form of specially prepared cartridges. Correct dissolution of tungsten in the metal bath was found, and there were no casting defects in the alloy. The form of carbide precipitates in the microstructure of cast iron was determined and the influence of increasing tungsten content on the reduction of the number of graphite precipitates in the structure was determined. Impact tests show that this property degrades with increasing tungsten content as opposed to hardness which increases. It was found that the addition of tungsten from machining waste is a potential source of enrichment of cast iron with this element.

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Bibliography

[1] Volkov, A.N. (1975). Abrasive wear resistance of manganese cast iron with tungsten. Metal Science and Heat Treatment. 17, 412-414.
[2] Duarte, L.I., Lourenço, N., Santos, H., Santos, J. & Sá, C. Tungsten carbide powder inserts in ductile iron. Materials Science Forum. 455-456, 267-270.
[3] Kopyciński, D. (2009). Analysis of the structure of castings made from chromium white cast iron resistant to abrasive wear. Archives of Foundry Engineering. 9(4), 109-112.
[4] Podrzucki, Cz. (1991). Cast Iron. The Structure, Property, Application. T.1 and T.2, Kraków: Ed. ZG STOP. (in Polish).
[5] Fraś, E. (2003). Crystallization of metals. Warsaw: WNT. (in Polish).
[6] Dean, N.F., Mortensen, A. & Flemings, M.C. (1994). Microsegregation in cellular solidification. Metallurgical And Materials Transactions A-Physical Metallurgy And Materials Science. A 25A, 2295-2301. DOI: 10.1007/BF 02652329.
[7] Wołczyński, W., Guzik, E., Kania, B. & Wajda, W. (2010). Structures field in the solidifying cast iron roll. Archives of Foundry Engineering. 10(spec.1), 41-46.
[8] Studnicki, A. (2008). Effect of boron carbide on primary crystallization of chromium cast iron. Archives of Foundry Engineering. 8(1), 173-176.
[9] Myszka, D. (2021). Cast Iron–Based Alloys. In: Rana, R. (eds) High-Performance Ferrous Alloys. Springer, Cham., 153-210.

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Authors and Affiliations

D. Myszka

Justyna Kasińska

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ORCID:

A. Penkul

Department of Metal Forming and Foundry, Warsaw University of Technology, Narbutta 85, Warsaw, Poland