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1
Content available remote

Method of Measuring the Distance to an Object Based on One Shot Obtained from a Motionless Camera with a Fixed-Focus Lens

100%
Murawski K.
Acta Physica Polonica A
|
2015
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vol. 127
|
issue 6
1591-1596
EN
The paper presents the method of measuring the distance to the object based on digital image processing. The solution is characterized in that the distance measurement to the object is performed by a motionless camera with established and unchanged parameters during measurement. The camera is equipped with a one non-stereoscopic lens. The measured distance is determined on the basis of one view of an object presented on one image. The image is made at a constant and invariant setting of the optical path such as: focus, aperture and focal length.
2
Content available remote

Alfvén-Magnetosonic Waves Interaction

100%
Murawski K.
Acta Physica Polonica A
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1992
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vol. 81
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issue 3
335-351
EN
The nonlinear propagation of the Alfvén and magnetosonic waves in the solar corona is investigated in terms of model equations. Due to viscous effects taken into account the propagation of the Alfvén wave itself is governed by a Burgers-type equation. The Alfvén waves exhibit a tendency to drive both the slow and fast magnetosonic waves. For this process model equations are a generalization of the Zakharov equations. The propagation of the magnetosonic waves is described by linearized Boussinesq-type equations with ponderomotive terms due to the Alfvén wave. Both long and short Alfvén waves are considered. Also the limits of the slow and fast modes are investigated. An approximate shock wave solution has been found for a vertically propagating slow mode. Numerical results for the fast mode propagating perpendicular to the magnetic field show the effect of inhomogeneity and pumping on a shock as the solution of the homogeneous Burgers equation.
3
Content available remote

Modified Nonlinear Schrödinger Equation for Nonlinear Waves in Optical Fibres

100%
Murawski K.
Acta Physica Polonica A
|
1991
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vol. 80
|
issue 4
485-493
EN
A new model equation governing the propagation of nonlinear pulses in optical fibres has been derived on the assumption of a saturated nonlinearity of the refractive index. This equation is a combination of the exponential nonlinear Schrödinger equation and the derivative one. It is valid for the long fibres. A modulational stability has been calculated to find out a cut-off in an angular frequency of a carrier wave. Moreover, it has been shown that the equation possesses family of stationary solutions. An initial value problem has been discussed on the basis of the implicit pseudo-spectral scheme.
4
Content available remote

Modulational Instability of Nonlinear Exponential Schrödinger Waves

100%
Murawski K.
Acta Physica Polonica A
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1991
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vol. 80
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issue 4
495-501
EN
Modulational instability of a plane wave of the nonlinear Schrödinger equation is discussed numerically on the basis of the pseudo-spectral method. The linear theory is verified and influence of the attenuation is considered.
5
Content available remote

New Vision Sensor to Measure and Monitor Gas Pressure

100%
Murawski K.
Acta Physica Polonica A
|
2015
|
vol. 128
|
issue 1
6-9
EN
The paper presents the construction and the use of a video sensor developed to measure air pressure. A characteristic feature of the device is pressure measurement based on digital image processing and self-diagnostics performed on the basis of an image. The paper presents the results of sensor calibration and measurements taken during the tests. It has been shown that the developed video-manometer model that is equipped with a flat diaphragm allows measuring the air pressure in the range of 0-100 mbar with an error less than 2%.
6
Content available remote

Measurement of Membrane Displacement Using a Motionless Camera

100%
Murawski K.
Acta Physica Polonica A
|
2015
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vol. 128
|
issue 1
10-14
EN
The paper presents a technique for measuring membrane displacements with one motionless camera. The method relies on measuring the distance to an object based on one image obtained from a motionless camera with a fixed-focus lens. It is proven that the used technique allows monitoring the frequency and amplitude of vibration. The tests were performed for the oscillation frequency in the range from 0.5 Hz to 6 Hz and deviations from the neutral position in the range of ± 3 mm.
7
Publication available in full text mode
Content available

Numerical solutions of magnetohydrodynamic equations

100%
Murawski K.
|
2011
|
issue 2
8
Content available remote

Optical Sensor to Monitor Pupillary Light Reflex

64%
Różanowski K., Murawski K.
Acta Physica Polonica A
|
2013
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vol. 124
|
issue 3
558-562
EN
The aim of the paper is to describe design of an optical sensor intended to analyze pupillary light reflex. It also presents the results of physiological adaptation mechanisms in human eye, i.e. response of the iris to changes in the intensity of light that falls on the retina of the eye under conditions of sensory deprivation. Pupillary light reflex is a closed loop nerve reflex. It controls the amount of light that reaches the retina. Based on the test results, an optical sensor was designed, fabricated and correctly calibrated. In comparative tests with the use of F^2D Fit-For-Duty, a commercial system by AMTech, selected pupillographic parameters were primarily evaluated (baseline pupil diameter, oscillations, reflex latency, maximum reaction time, pupil constriction time, pupil dilation time, and constriction amplitude) under conditions of diminished alertness, reduced ability to concentrate, increasing fatigue, and drowsiness. The solution comes as part of a mobile pupillography device intended to be assembled in cars and airplanes to identify conditions of lower alertness, reduced ability to concentrate, increasing fatigue and drowsiness in drivers, pilots and traffic controllers, and to trigger alarm and preventive measures, if necessary.
9
Content available remote

An Infrared Sensor for Eye Tracking in a Harsh Car Environment

64%
Różanowski K., Murawski K.
Acta Physica Polonica A
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2012
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vol. 122
|
issue 5
874-879
EN
The paper presents the optical sensor which is built for EyeTracker operating in car harsh environment. The sensor is based on USB high speed video infrared camera. Additional hardware was designed for control and emission of infrared light as well. The designed hardware and software of the sensor are described in the paper. Some results of work, including video processing, are also presented.
10
Publication available in full text mode
Content available

Godunov-type methods for two-component magnetohydrodynamic equations

64%
Murawski K., Tanaka T.
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2012
|
issue 2
11
Publication available in full text mode
Content available

A new CUDA-based GPU implementation of the two-dimensional Athena code

64%
Wasiljew A., Murawski K.
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2013
|
issue 1
12
Publication available in full text mode
Content available

Numerical methods of solving equations of hydrodynamics from perspectives of the code FLASH

64%
Murawski K., Lee D.
|
2011
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issue 1
13
Publication available in full text mode
Content available

Implementation of MUSCL-Hancock method into the C++ code for the Euler equations

64%
Murawski K., Stpiczyński P.
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2012
|
issue 1
14
Publication available in full text mode
Content available

Numerical simulations of acoustic waves with the graphic acceleration GAMER code

64%
Murawski K., Schive H.-Y.
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2012
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issue 4
15
Content available remote

Pattern Recognition Algorithm for Eye Tracker Sensor Video Data Analysis

64%
Murawski K., Różanowski K.
Acta Physica Polonica A
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2013
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vol. 124
|
issue 3
509-512
EN
The aim of the paper is to discuss research conducted at the Military University of Technology as well as the Military Institute of Aviation Medicine. The essence of the research is to develop a pattern recognition algorithm for the analysis of data received from an eye tracker sensor. Data analysis can be done using computer vision algorithms. In the article the state of the art pattern recognition algorithms were presented. Particular attention was paid to the possibilities and limitations of their use. The main part of the paper is the presentation of the author's pattern recognition algorithm. In the paper we have also shown the results obtained by other techniques of image processing, which are frequently used to determine the position of the pupil of the eye on the image.
16
Content available remote

Multifunctional, Optical Sensor for Analysis of Dynamic Pupillary Light Reflex

52%
Różanowski K., Lewandowski J., Murawski K.
Acta Physica Polonica A
|
2015
|
vol. 127
|
issue 3
723-729
EN
The aim of the publication is to describe the multifunctional optical sensor for analysis of dynamic pupillary light reflex developed by the authors which could be used as an objective indicator of human fatigue. The authors utilized knowledge gained from past experimental studies to develop a sensor, which along with custom software for detection of parameters of dynamic pupillary reflex provides a quick analysis of the human psychophysiological condition. Furthermore, the obtained parameters may also be utilized for medical purposes. The authors present the results of pilot studies prior to the development process of the sensory solution. The obtained result show that the type of light stimulation of the retina has a significant impact on the dynamic parameters of the pupillary reflex. The results played also an important role in shaping the structural assumptions of the sensor, so that it can serve as an indicator of the human fatigue level. The article includes results of experimental research conducted during the testing process of the sensor using various parameters of frequency light excitations, luminance and chrominance.
17
Content available remote

Measurement of Corneal Neovascularisation with the Use of Image Processing Techniques

52%
Murawski K., Białas D., Rękas M.
Acta Physica Polonica A
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2015
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vol. 127
|
issue 6
1732-1736
EN
The aim of the article is to present the developed technique to measure the degree of neovascularisation of the cornea image in visible light. The study used an image sensor attached to a slit lamp. The proposed technique consists in performing segmentation of the color image to enhance blood vessels and setting values of the degree of cornea neovascularisation. Comparison of the indicator before and after treatment of the cornea can objectively assess the effectiveness of the adopted method of treatment.
18
Content available remote

Reconstruction of Lost Fragments of Signal Received from the Wireless Sensor Measuring Fluid Pressure inside the Eye Ball

52%
Murawski K., Grad L., Rękas M.
Acta Physica Polonica A
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2015
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vol. 127
|
issue 6
1596-1600
EN
The aim of the paper is to present a technique of reconstructing data received from a wireless sensor for measuring intraocular pressure. The algorithm was developed to automatically regenerate samples lost due to fortuitous events in clinical trials. The test consisted in measuring the pressure within 24 h, during which the intraocular pressure curve were determined. The paper also discusses the structure and the physical basis of sensor operation and shows the advantages resulting from its use.
19
Content available remote

Impulsively Generated Linear and Non-Linear Alfvén Waves in the Coronal Funnels

52%
Chmielewski P., Srivastava A., Murawski K., Musielak Z.
|
|
vol. 125
|
issue 1
158-164
EN
We present simulation results of the impulsively generated linear and non-linear Alfvén waves in the weakly curved coronal magnetic flux-tubes (coronal funnels) and discuss their implications for the coronal heating and solar wind acceleration. We solve numerically the time-dependent magnetohydrodynamic equations to find the temporal signatures of the small and large-amplitude Alfvén waves in the model atmosphere of open and expanding magnetic field configuration with a realistic temperature distribution. We compute the maximum transversal velocity of both linear and non-linear Alfvén waves at different heights of the model atmosphere, and study their response in the solar corona during the time of their propagation. We infer that the pulse-driven non-linear Alfvén waves may carry sufficient wave energy fluxes to heat the coronal funnels and also to power the solar wind that originates in these funnels. Our study of linear Alfvén waves shows that they can contribute only to the plasma dynamics and heating of the funnel-like magnetic flux-tubes associated with the polar coronal holes.
20
Content available remote

Surface Waves along the Martian Ionopause

52%
Chmielewski P., Murawski K., Kumar N.
Acta Physica Polonica A
|
2013
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vol. 123
|
issue 1
156-161
EN
We study the behaviour of surface waves propagating along the ionopause of the planet Mars and derive the onset criteria for unstable Kelvin-Helmholtz modes and negative energy waves at the Martian ionopause. Growth rate of unstable Kelvin-Helmholtz mode decreases with wavelength. The backward propagating waves became negative energy waves for the ionosheath velocity higher than critical velocity. It is found that short wavelength surface waves propagating along the Martian ionopause are less dispersive than long waves.
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