Abstracts of papers for

Previous issue vol. 42, no. 1 (2001)

vol. 42, no. 2 (2001)

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Contents of issue 2, vol. 42

Review Paper

1. H.K. Lachowicz: Magnetic materials - progress and challenges

   Military Applications

2. E. Włodarczyk: Active mass of high explosive in the wedge-shaped charge
3. W.A. Trzciński: Application of a cylinder test for determining energetic characteristics of explosives
4. E. Włodarczyk: Effectiveness of the cylindrical hollow charge
5. J. Owsik, S. Usherenko, M. Meyers and A. Zarwalska: Analysis of shock interaction under super deep penetration effect
6. Z. Koruba: Adaptive correction of controlled gyroscope on the deck of aerial object
7. R. Dulski, T. Niedziela and H. Polakowski: Application of thermal-scene modelling to testing of decision algorithms
8. Z. Dżygadło and G. Kowaleczko: Nonlinear regular and chaotic dynamics of a helicopter

   Brief Notes

9. D. Rogula and T. Lenkowska-Czerwińska: Alternating states in layered high-T_c supeconductors
10. J. Janucki and J. Owsik: Optimisation of a rectangular-profile diffraction grating

H.K. Lachowicz: Magnetic materials - progress and challenges

The present paper gives a review of novel magnetic materials and magnetic thin film structures, the latter ones utilized mainly in magnetic recording technology. The survey is divided into three sections describing magnetically soft, semi-hard and hard materials, respectively. At the beginning of each section a brief history of the materials of the above classes is presented, whereas at the end, the research efforts towards invention of novel materials or improvement of the existing ones are described.

Contents

E. Włodarczyk: Active mass of high explosive in the wedge-shaped charge

The algebraic formulae, determining the active mass of the high explosive (HE) in the wedge-shaped charge warhead have been derived in the paper. Influences of the casing and liner inertia of the wedge cumulative warhead as well as of the liner shape on the active mass of the HE have been analysed. The presented simple formulae may be used by the engineers designing the shaped charges.

Contents

W.A. Trzciński: Application of a cylinder test for determining energetic characteristics of explosives

In the work expressions for an expansion work and detonation energy of condensed explosives are derived from a quasistatic cycle for detonation. New semiempirical methods of determination of the acceleration ability of detonation products and the detonation energy are proposed. The basis of the methods is a so-called cylinder test. The procedures of applying the cylinder test data for determining the acceleration ability (so-called Gurney energy) and for estimation of the detonation energy are described. The method proposed for evaluation of the detonation energy is verified by using the cylinder test data given in literature for 17 explosives.

Contents

E. Włodarczyk: Effectiveness of the cylindrical hollow charge

The influence of the cavity shape of the cylindrical cumulative charge on its effectiveness in destruction activity has been analysed in this paper. It is proved that the value of the efficiency coefficient h of the cylindrical hollow charge is determined, among other things, by the dimensions and the shape of the cavity. The values of the efficiency coefficient, for real hollow charges, are contained within the interval 1/9łmł1/5. The maximum active mass of the cylindrical hollow charge is described by the formula: m_a = p r₀³r_e/3, where r₀ is the radius of the cylindrical hollow charge, and r_e denotes the density of an explosive.

Contents

J. Owsik, S. Usherenko, M. Meyers and A. Zarwalska: Analysis of shock interaction under super deep penetration effect

When macrobodies undergo collision, macrocraters are formed for which the ratio of crater's depth to striker diameter does not exceed 10. At the end of the 70's, an anomalous effect of formation of microcraters with relative depth of about 10²-10⁴ of particle size has been detected. Analysis of the experimental results made it possible to reveal the existence of a narrow impact interaction zone within which craters-channels are produced with a good repeatability. Evidence of a limited relative depth under macroimpact is explained by restrictions imposed by energy intensity of impact interaction in a barrier material.

Contents

Z. Koruba: Adaptive correction of controlled gyroscope on the deck of aerial object

The paper presents the most general mathematical model of dynamics of the controlled gyroscope on the movable base (the deck of an aerial object). The method of the gyroscope system error correction employed an algorithm based on the idea of iteration procedure of the control of a nonlinear object of hardly known properties, which is affected by interference.

Contents

R. Dulski, T. Niedziela and H. Polakowski: Application of thermal-scene modelling to testing of decision algorithms

A way for the use of thermal-scene modelling to testing of decision algorithms for systems of automatic recognition in infrared is proposed. Taking two algorithms as an example, probabilities of detection and false alarm as a function of the signal threshold level and target observation angle are determined. The results of computations presented have been obtained by means of the authors' software.

Contents

Z. Dżygadło and G. Kowaleczko: Nonlinear regular and chaotic dynamics of a helicopter

A helicopter is a rotorcraft, which can be subjected, during its motion, to various types of vibrations. This paper presents selected results of analysis of these vibrations. It is carried out on the basis of the complete set of nonlinear differential equations describing the helicopter fuselage motion and all the blades motions. For the helicopter performing a steady-state flight, the control law for static autopilot is formulated on the basis of the method of motions separation. In the case of a ground resonance the forces and moments produced by a landing gear are taken into consideration. The flutter phenomenon is also simulated. Some results of numerical analysis are presented, which show that some oscillations are regular and others have rather a chaotic character.

Contents

D. Rogula and T. Lenkowska-Czerwińska: Alternating states in layered high-T_c supeconductors

The coupling between lattice distortion modes and the superconducting order parameters for the layered, high temperature superconductors of La214 class is considered. The set of structural micro-order parameters is determined on the ground of a model of coupled quasi-rigid CuO₆ octahedra. The admissible combinations of the superconducting micro-order parameter components are presented. The time reversal symmetry of microscopic and macroscopic states due to correlation between structural and superconducting order parameters is discussed.

Contents

J. Janucki and J. Owsik: Optimisation of a rectangular-profile diffraction grating

Analysis of properties of a diffraction grating used as a power splitter of laser radiation has been presented. Results of numerical calculations of diffraction grating characteristics as a function of their geometrical parameters, wavelength of radiation and incidence angle of the laser beam have been shown. Conclusions concerning the designs of radiation splitters have been formulated.

Contents