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Wyświetlanie 1-15 z 22
Tytuł:
Steganography in Audio Files: COTS Software Analysis
Autorzy:
Marszałek, Piotr
Bilski, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/2201248.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
steganography
audio
information hiding
steganalysis
encryption
compression
cybersecurity
cyberspace
embedding
information security
privacy
signal plane
non-signal plane
Opis:
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.
Źródło:
International Journal of Electronics and Telecommunications; 2023, 69, 1; 121--126
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Computational modeling of creep in complex plane for reinforced materials
Autorzy:
Monfared, V.
Powiązania:
https://bibliotekanauki.pl/articles/200821.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
creep
composite
complex plane
pełzanie
kompozyt
naprężenie płaskie
Opis:
Computational modeling for predicting the steady state creep behavior is presented in complex plane for reinforced materials by complex variable method. Both the fiber and matrix simultaneously creep at elevated temperatures and loading. We suppose that one dimension of the short fiber is small enough in comparison with the other two (see Fig. 1). In this formulation, plane stress state is used. Finally, displacement rate behaviors are predicted using compatibility, equilibrium, constitutive, and governing equations by complex variable method. One of the considerable applications of the method is in nano-composites analysis in elasticity or plasticity research.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2017, 65, 6; 909-916
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Model-based initial residual unbalance identification for rotating machines in one and two planes using an iterative inverse approach
Autorzy:
Bastakoti, Satish
Choudhury, Tuhin
Viitala, Risto
Kurvinen, Emil
Sopanen, Jussi
Powiązania:
https://bibliotekanauki.pl/articles/2090689.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
flexible rotor
inverse approach
onsite-balancing
residual unbalance
single plane
double plane
wirnik elastyczny
metoda odwrotna
płaszczyzna pojedyńcza
płaszczyzna podwójna
Opis:
To achieve acceptable dynamical behavior for large rotating machines operating at subcritical speeds, the balancing quality check at the planned service speed in the installation location is often demanded for machines such as turbo-generators or high-speed machines. While most studies investigate the balancing quality at critical speeds, only a few studies have investigated this aspect using numerical methods at operational speed. This study proposes a novel, model-based method for inversely estimating initial residual unbalance in one and two planes after initial grade balancing for large flexible rotors operating at the service speeds. The method utilizes vibration measurements from two planes in any single direction, combined with a finite element model of the rotor to inversely determine the residual unbalance in one and two planes. This method can be practically used to determine the initial and residual unbalance after the balancing process, and further it can be used for condition-based monitoring of the unbalance state of the rotor.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 6; e139790, 1--12
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurement of thermal behavior of detector array surface with the use of microscopic thermal camera
Autorzy:
Bieszczad, G.
Kastek, M.
Powiązania:
https://bibliotekanauki.pl/articles/220546.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
thermovision
microbolometer focal plane array
self-heating
microscopic thermography
Opis:
Modern infrared cameras are constructed with two main types of infrared detectors: photon detectors and thermal detectors. Because of economic reasons, vast numbers of modern thermal cameras are constructed with the use of infrared microbolometric detectors which belong to the group of thermal detectors. Thermal detectors detect incident infrared radiation by measuring changes of temperature on the surface of a special micro-bridge structure. Thermal detectors, like microbolometric detectors on one hand should be sensitive to changing temperature to accurately measure incoming infrared radiation from the observed scene, on the other hand there are many other phenomena that change the temperature of the detector and influence the overall response of the detector. In order to construct an accurate infrared camera, there is a need to evaluate these phenomena and quantify their influence. In the article the phenomenon of self heating due to the operation of the readout circuit is analyzed on an UL 03 19 1 detector. The theoretical analysis is compared with the results of conducted measurements. Measurements with a type SC7900VL thermographic camera were performed to measure the thermodynamic behavior of the UL 03 19 1 detector array.
Źródło:
Metrology and Measurement Systems; 2011, 18, 4; 679-690
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vector analysis of the current commutation in PM BLDC drives
Autorzy:
Buja, G.
Menis, R.
Keshri, R.
Powiązania:
https://bibliotekanauki.pl/articles/201920.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
PM BLDC drive
current commutation
stationary plane vector analysis
Opis:
The vector approach in either stationary or synchronous plane is commonly used for the analysis of the AC drives like induction and PM brushless AC drives whilst it has been hardly ever used for the PM brushless DC (BLDC) drives. A possible reason is that they require injection of square-wave currents into the motor phases, which are non-sinusoidal in nature. Recently, the PM BLDC drives have been analyzed by the help of the vector approach in the stationary plane. This paper applies such an approach to an in-depth analysis of the operation of the PM BLDC drives during the current commutations, illustrating the potentialities of the approach in giving a better insight into the current transients and the ensuing torque characteristics. At last, two voltage control strategies proposed to eliminate the torque ripple due to the current commutations are considered, showing that they can be readily understood by the vector approach.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2013, 61, 4; 829-836
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic Properties of Concrete Composite Panels under Eccentric Compression Loading Tests
Autorzy:
Magalhaes, M.
Silva, R. M.
Powiązania:
https://bibliotekanauki.pl/articles/176872.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
dynamic analysis
composite panels
in-plane loading
pre-stressed panels
Opis:
The main aim of this paper is to examine the variability of some dynamic properties of concrete composite panels to in-plane eccentric compression loads via static and dynamic impact testing. First, experimental tests were performed in order to obtain the dynamic and static properties of concrete composite panels. In-plane eccentric loads were statically applied to a couple of panels in ten uniform steps. For each step, dynamic impact testing was performed and the modal damping, peak amplitude and natural frequencies obtained. Second, a ‘hybrid’ model, based on the concepts of modal analysis and the Finite Element Method, was developed in order to obtain the natural frequencies and corresponding normal modes of the composite panels within the frequency range 0–200 Hz. For this model, an initial warp of the panel middle surface was incorporated into the formulation in order to represent the applied flexural moment provoked by the eccentric in-plane loads. The accuracy of the ‘hybrid’ model was verified by comparison with the experimental results. Third, comparison is made between predictions (using on the ‘hybrid’ model) and experimental results.
Źródło:
Archives of Acoustics; 2015, 40, 2; 169-181
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on Fretting Fatigue of Tungsten Carbide Coating Based on Strain Energy Density Methods
Autorzy:
Zeng, Xin
Wang, Xiaoxiao
Ping, Xuecheng
Wang, Renjie
Hu, Tao
Powiązania:
https://bibliotekanauki.pl/articles/2203727.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
WC coating
crack initiation
cracking angle
critical plane
life prediction
Opis:
The numerical solutions of stress and strain components on the critical plane of tungsten carbide coating were solved based on the critical plane method in three-dimensional coordinate system, and accordingly three strain energy density parameters (Smith-Watson-Topper, Nita-Ogatta-Kuwabara and Chen parameters) were determined to reveal the fretting fatigue characteristics of tungsten carbide coating. In order to predict the fretting fatigue life based on the strain energy density criterion, the expressions between the strain energy density parameter and the fretting fatigue life was obtained experimentally. After the comparison of the three strain energy parameters, it was found that all three parameters could accurately predict the crack initiation position, but only the Smith-Watson-Topper parameters could accurately predict the crack initiation angle. The effects of cyclic load, normal load and friction coefficient on fretting fatigue damage behaviors were discussed by using the Smith-Watson-Topper criterion. The results show that the fretting fatigue life decreases with the increase of cyclic load; an increase in the normal contact load will cause the Smith-Watson-Topper damage parameters more concentrated at the outer edge of the bridge foot; a decrease in the friction coefficient will increase the Smith-Watson-Topper damage parameters in the middle of the contact surface.
Źródło:
Archives of Metallurgy and Materials; 2023, 68, 1; 21--30
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reproduction of the control plane as a method of selection of settings for an adaptive fuzzy controller with Petri layer
Autorzy:
Derugo, Piotr
Żychlewicz, Mateusz
Powiązania:
https://bibliotekanauki.pl/articles/140496.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
control plane reproduction
DC drive
fuzzy controller tuning
Petri layer
Opis:
The purpose of this paper is to show possibility and advantages of initial control plane reproduction for an adaptive fuzzy controller. Usually the fuzzy control is used when the object is not very well known. Yet the truth is, however, that some, at least general information about the object, is available. Usually, in such a case, optimization algorithms are used to tune the control structure. The purpose of this article is to show how to find a starting point that is closer to optimum than a statistically random point, and this way to obtain better results in a shorter time.
Źródło:
Archives of Electrical Engineering; 2020, 69, 3; 609-624
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Investigation on Acoustic Wave Focalization by a Square Lattice Flat Lens
Autorzy:
Alagoz, S.
Powiązania:
https://bibliotekanauki.pl/articles/177219.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
square lattice sonic crystal
wave focusing
plane-wave expansion method
FDTD simulation
Opis:
A sonic crystal consists of a finite-size periodic array of scatters embedded in a background material. One of the fascinating properties of sonic crystals is the focusing phenomenon. In this study, the near field focusing effect of a solid-air 2D sonic crystal lens with a square lattice configuration is investigated in the second frequency band. The band structure and equifrequency contour of the crystal are analyzed to reveal the dispersion of an acoustic wave on the crystal structure. The frequency dependence of the acoustic wave focalization by the sonic crystal flat lens is demonstrated via Finite Difference Time Domain simulation results and experimental measurements.
Źródło:
Archives of Acoustics; 2012, 37, 1; 81-87
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Power-Ground Plane Impedance Modeling Using Deep Neural Networks and an Adaptive Sampling Process
Autorzy:
Goay, Chan Hong
Cheong, Zheng Quan
Low, Chen En
Ahmad, Nur Syazreen
Goh, Patrick
Powiązania:
https://bibliotekanauki.pl/articles/2200709.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
adaptive sampling
deep neural networks
deep learning
power-ground plane
Z-parameters
Opis:
This paper proposes a deep neural network (DNN) based method for the purpose of power-ground plane impedance modeling. A composite DNN model, which is a combination of two DNNs is used to predict the Z-parameters of power ground planes from their design parameters. The first DNN predicts the normalized Z-parameters whereas the second DNN predicts the original maximum and minimum values of the nonnormalized Z-parameters. This allows the method to retain a high accuracy when predicting responses that have large variations across designs, as is the case with the Z-parameters of the power-ground planes. We use the adaptive sampling algorithm to generate the training and validation samples for the DNNs. The adaptive sampling algorithm starts with only a few samples, then slowly generates more samples in the non-linear regions within the design parameters space. The level of non-linearity of the regions is determined by a surrogate model which is also trained using the generated samples as well. If the surrogate model has poor prediction accuracy in a region, then the adaptive sampling algorithm will generate more samples in that region. A shallow neural network is used as the surrogate model for non-linearity determination of the regions since it is faster to train and update. Once all the samples have been generated, they will be used to train and validate the composite DNN models. Finally, we present two examples, a square-shaped power ground plane and a squareshaped power ground plane with a hollow square at the center to demonstrate the robustness of the DNN composite models.
Źródło:
International Journal of Electronics and Telecommunications; 2022, 68, 4; 793--798
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reflection and Transmission of Plane Wave at an Interface Between Two Rotating Micropolar Piezoelectric Solid Half-Spaces
Autorzy:
Singh, Baljeet
Sangwan, Asha
Singh, Jagdish
Powiązania:
https://bibliotekanauki.pl/articles/2141703.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
plane wave
micropolar piezoelectricity
reflection and transmission
amplitude ratios
energy ratios
rotation
Opis:
In this paper, we investigate a problem on reflection and transmission of plane-waves at an interface between two dissimilar half-spaces of a transversely isotropic micropolar piezoelectric material. The entire model is assumed to rotate with a uniform angular velocity. The governing equations of rotating and transversely isotropic micropolar piezoelectric medium are specialized in a plane. Plane-wave solutions of two-dimensional coupled governing equations show the possible propagation of three coupled plane-waves. For an incident plane-wave at an interface between two dissimilar half-spaces, three reflected and three transmitted waves propagate with distinct speeds. The connections between the amplitude ratios of reflected and transmitted waves are obtained. The expressions for the energy ratios of reflected and transmitted waves are also obtained. A numerical example of the present model is considered to illustrate the effects of rotation on the speeds and energy ratios graphically.
Źródło:
Archives of Acoustics; 2021, 46, 4; 623-635
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Swarm optimization of stiffeners locations in 2-D structures
Autorzy:
Szczepanik, M.
Burczyński, T.
Powiązania:
https://bibliotekanauki.pl/articles/201314.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
swarm algorithms
optimization
finite element method
bars
plane stress
bending plates
shells
Opis:
The paper is devoted to the application of the swarm methods and the finite element method to optimization of the stiffeners location in the 2-D structures (plane stress, bending plates and shells). The structures are optimized for the stress and displacement criteria. The numerical examples demonstrate that the method based on the swarm computation is an effective technique for solving the computer aided optimal design. The additional comparisons of the effectiveness of the particle swarm optimizer (PSO) and evolutionary algorithms (EA) are presented.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2012, 60, 2; 241-246
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Ovality in Inlet Pigtail Pipe Bends Under Combined Internal Pressure and in-Plane Bending for Ni-Fe-Cr B407 Material
Autorzy:
Ramaswami, P.
Senthil Velmurugan, P.
Rajasekar, R.
Powiązania:
https://bibliotekanauki.pl/articles/352083.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ovality
inlet pigtail pipe bend
reformer
finite element analysis
in-plane bending
Opis:
The present paper makes an attempt to depict the effect of ovality in the inlet pigtail pipe bend of a reformer under combined internal pressure and in-plane bending. Finite element analysis (FEA) and experiments have been used. An incoloy Ni-Fe-Cr B407 alloy material was considered for study and assumed to be elastic-perfectly plastic in behavior. The design of pipe bend is based on ASME B31.3 standard and during manufacturing process, it is challenging to avoid thickening on the inner radius and thinning on the outer radius of pipe bend. This geometrical shape imperfection is known as ovality and its effect needs investigation which is considered for the study. The finite element analysis (ANSYS-workbench) results showed that ovality affects the load carrying capacity of the pipe bend and it was varying with bend factor (h). By data fitting of finite element results, an empirical formula for the limit load of inlet pigtail pipe bend with ovality has been proposed, which is validated by experiments.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 3; 1881-1887
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructure and texture evolution during annealing of plane strain compressed Al and Al-1%Mn alloy single crystals
Ewolucja mikrostruktury i tekstury podczas wyżarzania monokryształów Al i Al-1%Mn odkształcacnych w płaskim stanie odkształcenia
Autorzy:
Miszczyk, M.
Paul, H.
Driver, J. H.
Maurice, Cl.
Powiązania:
https://bibliotekanauki.pl/articles/352673.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
mikrostruktura
tekstura
płaski stan odkształcenia
rekrystalizacja
microstructure
texture
nucleation & recrystallization
plane strain compression
Opis:
The microstructure and the texture evolutions of partly recrystallized samples of pure Al and the Al-1%wt. Mn alloy have been characterized by a high resolution SEM/EBSD. The single crystals of the Goss{110}<001> and brass{110}<112> orientations, stable in the plane strain compression, were deformed in a channel-die up to 60% to develop a homogeneous structure composed of two sets of symmetrical primary microbands and then shortly annealed. It is documented that the orientations of the initial nucleus were scattered but not accidental. The disorientation axes in the orientation relationship across the recrystallization front usually coincide with one of the <112>, <221>, <102> or <111> crystallographic directions and were rather rarely close to the <110> or <001> directions. The disorientation axis of the <111>- type is only one of the few most often observed.
Przemiany tekstury w poczatkowych stadiach rekrystalizacji sa przedmiotem intensywnych badan, zwłaszcza tych które dotycza półwyrobów płaskich stosowanych w przemysle do wytwarzania opakowan droga głebokiego tłoczenia. W niniejszej pracy wykorzystano wysokorozdzielczy system SEM/EBSD do analizy tych zmian w nieswobodnie sciskanych próbkach aluminium oraz stopu Al-1%Mn. Dla przejrzystosci prowadzonej analizy, w badaniach wykorzystano próbki monokrystaliczne, o orientacjach stabilnych w płaskim stanie odkształcenia, tj. Gossf110g<001> i brassf110g<112>. Poddano je nieswobodnemu sciskaniu (powszechnie uznawanemu za modelowe przyblizenie procesu walcowania) do 40% i 60%, a nastepnie analizowano ich zachowanie w poczatkowych stadiach rekrystalizacji. W stanie po deformacji obserwowano jednorodna strukture dwu symetrycznie usytuowanych rodzin mikropasm, która w procesie rekrystalizacji sprzyjała pojawieniu sie nowych ziaren. Udokumentowano, ze orientacje poczatkowych ziaren, wyrastajacych ze struktury stanu zdeformowanego nie sa przypadkowe, i tylko scisle okreslona liczba grup orientacji moze sie pojawic w poczatkowym stadium wyzarzania. Dezorientacja obliczona poprzez migrujacy front rekrystalizacji zwiazana jest najczesciej z rotacja dookoła kierunków krystalograficznych typu <112>, <221>, <102> lub <111>, oraz rzadziej <110> lub <001>. Os dezorientacji typu <111> jest tylko jedna z kilku czesciej spotykanych.
Źródło:
Archives of Metallurgy and Materials; 2011, 56, 4; 933-938
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Using PWE/FE Method to Calculate the Band Structures of the Semi-Infinite PCs : Periodic in x-y Plane and Finite in z–direction
Autorzy:
Qian, D.
Shi, Z.
Powiązania:
https://bibliotekanauki.pl/articles/176974.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
semi-infinite phononic crystal
coupled plane wave expansion
finite element method
band structure
Opis:
This paper introduces the concept of semi-infinite phononic crystal (PC) on account of the Infinite periodicity in x-y plane and finiteness in z-direction. The plane wave expansion and finite element methods are coupled and formulized to calculate the band structures of the proposed periodic elastic composite structures based on the typical geometric properties. First, the coupled plane wave expansion and finite element (PWE/FE) method is applied to calculate the band structures of the Pb/rubber, steel/epoxy and steel/aluminum semi-infinite PCs with cylindrical scatters. Then, it is used to calculate the band structure of the Pb/rubber semi-infinite PC with cubic scatter. Last, the band structure of the rubbercoated Pb/epoxy three-component semi-infinite PC is calculated by the proposed method. Besides, all the results are compared with those calculated by the finite element (FE) method implemented by adopting COMSOL Multiphysics. Numerical results and further analysis demonstrate that the proposed PWE/FE method has strong applicability and high accuracy.
Źródło:
Archives of Acoustics; 2017, 42, 4; 735-742
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 22

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