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Tytuł:
Studies of Permittivity in the Triglicinium Sulphate Crystals Doped with Chromium Ions as a Function of Temperature and Electric Field
Autorzy:
Dziedzic, J.
Powiązania:
https://bibliotekanauki.pl/articles/2014251.pdf
Data publikacji:
2000-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Kb
Opis:
Permittivity in the triglicinium sulphate crystals doped with chromium ions Cr$\text{}^{3+}$ as a function of temperature and of intensity of electric field polarising the crystal was investigated. On the base of thermodynamical theory, the relationship among permittivity, temperature and electric field intensity was calculated. Coefficients of the expansion of the thermodynamic potential were determined. Experimental results were compared with those resulting from the thermodynamical theory.
Źródło:
Acta Physica Polonica A; 2000, 98, 4; 373-381
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Obtaining ionic forces by the total-energy tight-binding method
Autorzy:
Dziedzic, J.
Powiązania:
https://bibliotekanauki.pl/articles/1933173.pdf
Data publikacji:
2007
Wydawca:
Politechnika Gdańska
Tematy:
total-energy tight-binding
TBMD
Hellmann-Feynman
ionic forces
molecular dynamics
Opis:
Applying a non-orthogonal tight-binding method to calculate ionic forces in a molecular-dynamics simulation vastly improves the transferability the model's transferability to different environments, compared with the tradi-tional empirical potential-driven molecular-dynamics. In this paper we present the details of computing derivatives of Hamiltonian and overlap matrix elements appearing in the Hellmann-Feynman expression for ionic forces in the NRL-TB model of tight-binding. The presented expressions are validated with the results obtained using a tight-binding-driven molecular-dynamics program.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2007, 11, 3; 285-294
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Studies of Elastic Waves Propagation in Triglycine Sulphate Crystals Doped with Chromium Ions
Autorzy:
Dziedzic, J.
Powiązania:
https://bibliotekanauki.pl/articles/2029264.pdf
Data publikacji:
2001-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Kb
Opis:
Velocities and scattering of transverse elastic wave propagating in the triglycine sulphate crystal doped with the Cr$\text{}^{3+}$ ions as a function of temperature and electric field which polarises the crystal were examined. Temperature dependencies of modulus of elasticity S$\text{}_{55}$ and modulus of rigidity C$\text{}_{55}$ as a function of temperature and an electric field were determined. The results were analysed and discussed.
Źródło:
Acta Physica Polonica A; 2001, 100, 6; 879-884
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quantum-classical calculations of the nanomechanical properties of metals
Autorzy:
Dziedzic, J.
Powiązania:
https://bibliotekanauki.pl/articles/1964138.pdf
Data publikacji:
2009
Wydawca:
Politechnika Gdańska
Tematy:
hybric methods
cross-scaling
tight-binding
learn-on-the-fly
nanoscale
metals
nanoindentation
molecular-dynamics
Sutton-Chen potential
Opis:
Molecular-dynamics (MD) simulations constitute an important tool in the study of nanoscale metallic systems, especially so in the face of the difficulties plaguing their experimental analysis. Main limitations of the MD method stem from the empirical nature of the potentials employed, their functional form which is postulated ad hoc, and its classical nature. The neglect of electronic effects and the unjustified utilization of the potential for system configurations significantly different from those, for which the potential was parametrized makes the results of strictly classical calculations dubious, at least for a certain class of systems. On the other hand, high computational complexity of quantum-based methods, where atomic interactions are described ab initio, prohibits their direct use in the study of systems larger than several tens of atoms. In the last decade, a growing popularity of so-called hybrid (or cross-scaling) methods can be observed, that is, methods which treat the most interesting part of the system with a quantum-based approach, while the remainder is treated classically. Physically sound handshaking between the two methodologies (quantum and classical) within a single simulation constitutes a serious challenge, the majority of difficulties concentrating around the interface between the fragments of the system treated with the two methods. The aforementioned interface is most easily constructed for covalently bonded systems, where the bonds cut by the isolation of the quantum-based region can be saturated by the introduction of specially crafted link-atoms. In metallic systems, however, due to electronic delocalization, this traditional approach cannot be employed. This paper describes a physically sound and adequately efficient computational technique, which allows for the inclusion of results of locally employed quantum-based computations within a molecular-dynamics simulation, for systems described by the many-body Sutton-Chen (SC) potential, used in the study of fcc metals. The proposed technique was developed taking as a point of departure the Learn-on-the-Fly (LOTF) formalism, a recent development itself. The original LOTF approach is only suitable for two- or three-body potentials and is serial in nature, whereas the proposed technique can be used with many-body potentials and is parallel-ready. An implementation of the proposed approach in the form of computer code, which allows for parallel hybrid computations for metallic systems is also described. Finally, results from a set of hybrid simulations of nanoindentation of a copper workmaterial with a hard indenter utilizing the aforementoned technique and computer code is presented, as evidence of its viability.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2009, 13, 3; 207-310
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ferroelectric Phase Transition in DC Electric Field in [NH$\text{}_{2}$(CH$\text{}_{3}$)$\text{}_{2}$]$\text{}_{3}$Sb$\text{}_{2}$Cl$\text{}_{9}$ Crystals
Autorzy:
Dziedzic, J.
Mróz, J.
Powiązania:
https://bibliotekanauki.pl/articles/2047351.pdf
Data publikacji:
2007-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Kb
Opis:
Dielectric investigations of ferro-paraelectric phase transition under influence of bias pooling DC electric field ranging from 0 to 500 kV/m were performed for [NH$\text{}_{2}$(CH$\text{}_{3}$)$\text{}_{2}$]$\text{}_{3}$Sb$\text{}_{2}$Cl$\text{}_{9}$. The linear shift of T$\text{}_{c}$ towards higher temperatures was observed. The A$\text{}_{0}$ and B coefficients from the Landau state equation are determined.
Źródło:
Acta Physica Polonica A; 2007, 111, 6; 873-876
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Voice command recognition using hybrid genetic algorithm
Autorzy:
Wroniszewska, M.
Dziedzic, J.
Powiązania:
https://bibliotekanauki.pl/articles/1955309.pdf
Data publikacji:
2010
Wydawca:
Politechnika Gdańska
Tematy:
voice command recognition
genetic algorithms
K-nearest neighbour
hybrid approach
Opis:
Speech recognition is a process of converting the acoustic signal into a set of words, whereas voice command recognition consists in the correct identification of voice commands, usually single words. Voice command recognition systems are widely used in the military, control systems, electronic devices, such as cellular phones, or by people with disabilities (e.g., for controlling a wheelchair or operating a computer system). This paper describes the construction of a model for a voice command recognition system based on the combination of genetic algorithms (GAs) and K-nearest neighbour classifier (KNN). The model consists of two parts. The first one concerns the creation of feature patterns from spoken words. This is done by means of the discrete Fourier transform and frequency analysis. The second part constitutes the essence of the model, namely the design of the supervised learning and classification system. The technique used for the classification task is based on the simplest classifier – K-nearest neighbour algorithm. GAs, which have been demonstrated as a good optimization and machine learning technique, are applied to the feature extraction process for the pattern vectors. The purpose and main interest of this work is to adapt such a hybrid approach to the task of voice command recognition, develop an implementation and to assess its performance. The complete model of the system was implemented in the C++ language, the implementation was subsequently used to determine the relevant parameters of the method and to improve the approach in order to obtain the desired accuracy. Different variants of GAs were surveyed in this project and the influence of particular operators was verified in terms of the classification success rate. The main finding from the performed numerical experiments indicates the necessity of using genetic algorithms for the learning process. In consequence, a highly accurate recognition system was obtained, providing 94.2% correctly classified patterns. The hybrid GA/KNN approach constituted a significant improvement over the simple KNN classifier. Moreover, the training time required for the GA to learn the given set of words was found to be on a level that is acceptable for the efficient functioning of the voice command recognition system.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2010, 14, 4; 377-396
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on Pyroelectric Properties of the TGS-TGSe Crystals with Internal Electric Field
Autorzy:
Dziedzic, J.
Mróz, J.
Powiązania:
https://bibliotekanauki.pl/articles/2044565.pdf
Data publikacji:
2005-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Kb
Opis:
Measurements of spontaneous polarization and pyroelectric coefficient versus temperature and electric field were performed for the TGS-TGSe crystals at a definite internal electric field. The obtained results are compared with the thermodynamic theory predictions. The temperature and electric field dependencies of pyroelectric coefficient are presented together with its maximal value as a function of the electric field intensity. It was shown that the temperature, at which the pyroelectric coefficient reaches its maximal value, depends on the external electric field.
Źródło:
Acta Physica Polonica A; 2005, 108, 6; 971-978
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of Spontaneous Polarisation and Pyroelectric Modulus for the Triglycine Sulphate Crystals Doped by Chromium Ions
Autorzy:
Dziedzic, J.
Stolecki, B.
Powiązania:
https://bibliotekanauki.pl/articles/2014061.pdf
Data publikacji:
2000-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Kb
Opis:
The temperature dependencies of a spontaneous polarisation, P$\text{}_{s}$, and pyroelectric modulus, γ, at different electric field intensities were investigated for the triglycine sulphate crystals doped with the Cr$\text{}^{3+}$ chromium ions. On the base of thermodynamic theory the temperature dependencies of P$\text{}_{s}$ and γ at different electric field intensities were estimated. The coefficients of the expansion of the thermodynamic potential were determined. The experimental results were compared with those obtained according to the thermodynamic theory.
Źródło:
Acta Physica Polonica A; 2000, 98, 1-2; 55-60
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ultrathin Glass for the Photovoltaic Applications
Autorzy:
Dziedzic, J.
Inglot, M.
Powiązania:
https://bibliotekanauki.pl/articles/1032413.pdf
Data publikacji:
2017-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
84.60.Jt
71.20.Nr
72.40.+w
42.70.-a
85.60.-q
Opis:
Chemically strengthened ultrathin glass with a thickness of less than 1 mm has many advantages, such as flexibility, smooth surface, good transmittance, excellent gas and water barrier, much higher toughened in relations to thermally tempered glass, higher impact resistance, increased corrosion resistance and much higher abrasion rate. Chemical strengthening process is a process where an ion exchange occurs by diffusion between the glass panes and the brine solution bath. The deeper penetration of the glass surface by ions contained in the brine bath contributes to the hardness of the glass sheets, which reduces the occurrence of surface defects that cause reflections. From the point of view of photovoltaic applications ultrathin glass significantly reduces the weight of the whole photovoltaic panel structure with respect to known solutions. Furthermore, the reduction of the glass thickness increases the transmission of solar energy in the visible range directly through the glass. In addition, chemical tempered glass has a lower reflectance of light from the surface than the thermally tempered glass. What is more, ultrathin glass is perfect substrate for deposition of nanomaterials, i.e. conductive films or quantum dots. In this work we demonstrate that chemically strengthened ultrathin glass is a perfect material for the photovoltaic applications, i.e. as a substrate for deposition of thin layers and for the design of photovoltaic modules of reduced weight.
Źródło:
Acta Physica Polonica A; 2017, 132, 1; 176-178
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dielectric Properties of the (CH$\text{}_{3}$NH$\text{}_{3}$)$\text{}_{5}$Bi$\text{}_{2(1- x)}$Sb$\text{}_{2x}$Cl$\text{}_{11}$ Mixed Crystals
Autorzy:
Mróz, J.
Dziedzic, J.
Pykacz, H.
Powiązania:
https://bibliotekanauki.pl/articles/2047087.pdf
Data publikacji:
2006-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Kb
Opis:
The (CH$\text{}_{3}$NH$\text{}_{3}$)$\text{}_{5}$Bi$\text{}_{2(1-x)}$Sb$\text{}_{2x}$Cl$\text{}_{11}$ crystals were examined from the point of view of their applicability in pyroelectric detectors. It was shown that they can be useful so far as the construction of infrared detectors is concerned due to high values of both their pyroelectric coefficient and figure of merit p/sqrtε which are both comparable with those of triglycine sulphate crystals.
Źródło:
Acta Physica Polonica A; 2006, 110, 4; 479-483
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pyroelectric and Dilatometric Studies on the Low Temperature Ferroelectric Phase Transition of (CH$\text{}_{3}$NH$\text{}_{3}$)$\text{}_{5}$Bi$\text{}_{2}$Br$\text{}_{11}$
Autorzy:
Dziedzic, J.
Mróz, J.
Jakubas, R.
Powiązania:
https://bibliotekanauki.pl/articles/2043695.pdf
Data publikacji:
2005-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
77.80.Bh
Opis:
The results of the linear thermal expansion studies on (CH$\text{}_{3}$NH$\text{}_{3}$)$\text{}_{5}$Bi$\text{}_{2}$Br$\text{}_{11}$ single crystals in the temperature range 60-340 K are presented. The thermal anomaly in the vicinity of 77 K is assigned to the phase transition classified as close to first order type. The pyroelectric measurements of (CH$\text{}_{3}$NH$\text{}_{3}$)$\text{}_{5}$Bi$\text{}_{2}$Br$\text{}_{11}$ were carried out in the range of 45-320 K along the a- and c-axis. The step-like change in the spontaneous polarization along the a-axis at 77 K indicates a discontinuous character of ferroelectric transition.
Źródło:
Acta Physica Polonica A; 2005, 108, 3; 505-511
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Metodyka oceny uszkodzenia elementów konstrukcyjnych na przykładzie belki izotropowej jednostronnie utwierdzonej
Methodology of structures damage estimation in case of cantilever isotropic beam
Autorzy:
Samborski, S.
Wieczorkiewicz, J.
Rusinek, R.
Dziedzic, J.
Powiązania:
https://bibliotekanauki.pl/articles/101810.pdf
Data publikacji:
2015
Wydawca:
Politechnika Lubelska. Polskie Towarzystwo Promocji Wiedzy
Tematy:
detekcja uszkodzeń
belka wspornikowa
płaszczyzna fazowa
damage detection
cantilever beam
phase space diagram
Opis:
W pracy zbudowano model numeryczny belki wspornikowej z uszkodzeniem i bez uszkodzenia oraz wyznaczono ichczęstości własne dla zadanych charakterystyk mate-riałowych. Następnie przeprowadzono badania na fizycznym obiekcie przy użyciu wibrometru laserowego PSV-500 firmy Polytec. Otrzymane rezultaty doświadczalne porównano z wynikami obliczeń nume-rycznych stosując metody analizy sygnału oparte na wykresach płaszczyzny fazowej.
This paper focuses on analysis of damage detection cantilever beam. Finite Element Method was used to simulate vibrations of the intact and the damaged beams. Analysis of natural frequencies of both the intact and the damaged beams was performed in order to observe the effect of damage on the beams dynamics. Next, the phase diagrams technique was applied andfinally, experimental verification was performed to check the numerical results.
Źródło:
Journal of Technology and Exploitation in Mechanical Engineering; 2015, 1, 1-2; 5-16
2451-148X
Pojawia się w:
Journal of Technology and Exploitation in Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
MD simulations of ultraprecision machining of fcc monocrystals
Autorzy:
Rychcik-Leyk, M.
Białoskorski, M.
Dziedzic, J.
Rybicki, J.
Powiązania:
https://bibliotekanauki.pl/articles/1943186.pdf
Data publikacji:
2010
Wydawca:
Politechnika Gdańska
Tematy:
nanomachining
nanocutting
nanomechanical properties
nanoplasticity
Opis:
In technical sciences, the term "machining" refers to the process of forming an object into a desired shape and size, with a desired quality of surface, by removing layers of its material by means of a cutting tool. The paper describes research on ultra-precision machining (UPM), where the abovementioned process takes place on the atomic level and involves systems (a machined object and a tool) several dozen nanometers in size. Three-dimensional computer simulations (virtual experiments) of UPM of monocrystalline copper with an infinitely hard tool were performed utilizing the classical molecular dynamics (MD) method with a many-body potential to describe the interatomic interactions. Among the examined issues were: the effect of the tool shape, machining speed and depth on the obtained workmaterial surfaces, and on the stresses, slip patterns and local temperature increases generated during the process.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2010, 14, 1-2; 35-167
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling the contact of stiff and soft bodies with a rigid support by short range force fields
Autorzy:
Contento, A.
Di Egidio, A.
Dziedzic, J.
Tatone, A.
Powiązania:
https://bibliotekanauki.pl/articles/1943218.pdf
Data publikacji:
2009
Wydawca:
Politechnika Gdańska
Tematy:
impast
contact
short range interaction
soft body dynamice
Opis:
Body impact-contact dynamics is a classical subject in mechanics. Most of the papers on the subject are based on a kinematical or impulse-exchange approach. In this paper a different approach has been adopted. It consists in assigning a constitutive description for the contact forces between the boundaries of bodies which get close to each other. In particular, a field of short range forces has been used to model the interaction between an affine body and the planar surface of a fixed rigid support. These forces are able to describe the impact, friction and adhesion allowing the body to have complex motions which look rather realistic. By an affine body we mean a body which undergoes affine, or homogeneous, deformations. Depending on the material, such a body can show very different behavior, from a quite rigid motion to a motion characterized by very large deformations. A soft body is assumed to be made of a viscous incompressible Mooney-Rivlin material. Though a microscopic model of surface interaction could be used in a multiscale approach, the description provided here is macroscopic only.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2009, 13, 1-2; 155-181
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł

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