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Wyszukujesz frazę "Czechowski, G." wg kryterium: Autor


Tytuł:
Viscosity Behavior at the Nematic to Smectic A Phase Transition in Freely Flowing Compounds
Autorzy:
Jadżyn, J.
Czechowski, G.
Powiązania:
https://bibliotekanauki.pl/articles/2037296.pdf
Data publikacji:
2004-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Md
83.80.Xz
66.20.+d
Opis:
The paper shows that the shear viscosity at the nematic to smectic A phase transition in freely flowing n-hexyloxycy$ $anobiphenyl + n-octyloxycyanobiphenyl mixtures (a system exhibiting the reentrant nematic phase) corresponds to the Mięsowicz η$\text{}_{3}$ viscosity coefficient and its temperature behavior is analogous (but strongly enhanced) to that observed for the η$\text{}_{2}$ viscosity coefficient at the isotropic to nematic phase transition.
Źródło:
Acta Physica Polonica A; 2004, 105, 5; 459-465
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Singular Elastic Properties of Mixtures with the Re-entrant Nematic Phase
Autorzy:
Czechowski, G.
Jadżyn, J.
Powiązania:
https://bibliotekanauki.pl/articles/2038376.pdf
Data publikacji:
2004-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Md
62.20.Dc
61.30.-v
Opis:
The paper presents temperature behavior of the splay and bend elastic constants measured for n-hexyloxycyanobiphenyl and n-octyloxycyanobiphenyl mixtures - a system exhibiting the re-entrant nematic phase. It was shown that singularities in the elastic properties of the system concern not only the nematic phase (the well-known pre-smectic effects) but first of all - the smectic A phase, in which the splay and bend deformations, normally not allowed for the layered structures, can be induced.
Źródło:
Acta Physica Polonica A; 2004, 106, 4; 475-485
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dielectric, Viscous, and Elastic Properties of Mesogenic 4-n-Hexyloxy-4-Cyanobiphenyl
Autorzy:
Czechowski, G.
Jadżyn, J.
Powiązania:
https://bibliotekanauki.pl/articles/2027368.pdf
Data publikacji:
2001-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Md
77.84.Nh
77.22.Gm
66.20.+d
Opis:
The paper presents the results of measurements of the static and dynamic electric permittivity, the shear viscosity, and the splay and bend elastic constants for 4-n-hexyloxy-4' -cyanobiphenyl (C$\text{}_{6}$H$\text{}_{13}$O-Ph-Ph-C≡N). On the basis of the static values of the nematic principal permittivities, ε$\text{}_{ǁ}$ (T) and $\varepsilon_{\bot}(T)$, the angle between the dipole moment vector and the long axis of 4-n-hexyloxy-4'-cyanobiphenyl molecule, the apparent dipole moment and the nematic order parameter were determined. From the temperature dependences of the dielectric relaxation time (corresponding to the molecular rotation around the short axis) and the shear viscosity, the strength of the nematic potential and the effective length of 4-n-hexyloxy-4'-cyanobiphenyl molecule (in isotropic phase) were estimated. The K$\text{}_{11}$ and K$\text{}_{33}$ elastic constants were determined from the voltage dependence of the capacitance of the planar nematic cell with the method proposed by Gruler et al. and Uchida et al.
Źródło:
Acta Physica Polonica A; 2001, 99, 5; 579-591
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temperature Dependence of the Viscosity of Isotropic Liquids
Autorzy:
Jadżyn, J.
Czechowski, G.
Lech, T.
Powiązania:
https://bibliotekanauki.pl/articles/2030494.pdf
Data publikacji:
2002-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
66.20.+d
83.85.Jn
Opis:
Temperature dependence of the shear viscosity measured for isotropic liquids belonging to the three homologous series: 4-(trans-4'-n-alkylcyclohexyl) isothiocyanatobenzenes (C$\text{}_{n}$ H$\text{}_{2n+1}$ CyHx Ph NCS; nCHBT, n=0÷12), n-alkylcyanobiphenyls (C$\text{}_{n}$H$\text{}_{2n+1}$ Ph Ph CN; nCB, n=2÷12) and 1,n-alkanediols (HO(CH$\text{}_{2}$)$\text{}_{n}$OH; 1,nAD, n=2÷10) were analysed with the use of Arrhenius equation and its two modifications: Vogel-Fulcher and proposed in this paper. The extrapolation of the isothermal viscosity of 1,n-alkanediols (n=2÷10) to n=1 leads to an interesting conclusion concerning the expected viscosity of methanediol, HOCH$\text{}_{2}$OH, the compound strongly unstable in a pure state.
Źródło:
Acta Physica Polonica A; 2002, 101, 4; 495-503
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Viscous Behavior of Binary Mixtures of Mesogenic Solvent/Non-Mesogenic Solute
Autorzy:
Jadżyn, J.
Czechowski, G.
Laskowski, S.
Powiązania:
https://bibliotekanauki.pl/articles/2046831.pdf
Data publikacji:
2006-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Md
66.20.+d
83.80.Xz
83.85.Jn
Opis:
The paper presents results of the shear viscosity measurements performed on diluted binary mixtures of mesogenic solvent n-hexylcyanobiphenyl (C$\text{}_{6}$H$\text{}_{13}$PhPhC≡N,6CB) and two non-mesogenic admixtures: (i) n-heptylcyanophenyl (C$\text{}_{7}$H$\text{}_{15}$PhC≡N,7CP), composed of the molecules of the same polarity as the solvent molecules but of a slightly shorter length, and (ii) 4-n-propylcyclohexyl-4'-n-pentylphenyl (C$\text{}_{3}$H$\text{}_{7}$CyHxPhC$\text{}_{5}$H$\text{}_{11}$,3CyP5), composed of the non-polar molecules but of a length very close to that of the mesomorphic solvent molecules. The experiment showed that the concentrational depression of the clearing temperature and the temperature extent of the isotropic + nematic (I + N) two-phase region in the mixtures are significantly smaller, i.e. the nematic phase is more thermodynamically stable, when the admixture molecular length is compatible to that of the mesogenic solvent, regardless of the polarity of the admixture molecules. The activation energy for freely flowing mixtures in the isotropic, nematic, and two-phase I + N regions was determined and discussed.
Źródło:
Acta Physica Polonica A; 2006, 109, 6; 723-730
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Singular Pretransitional Behavior of the Electric Field-Dependent Part of the Thermodynamic Quantities of Strongly Polar Mesogenic Liquids in the Isotropic Phase
Autorzy:
Jadżyn, J.
Déjardin, J.-L.
Czechowski, G.
Powiązania:
https://bibliotekanauki.pl/articles/2047352.pdf
Data publikacji:
2007-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Md
65.40.Gr
77.22.Ch
Opis:
A new interpretation of the pretransitional temperature behavior of the static dielectric permittivity and its derivative in terms of the basic thermodynamic quantities: the internal energy, the entropy, and the Helmholtz free energy is presented. It was shown that in the case of strongly polar mesogenic compounds (as the homologous series of alkylcyanobiphenyls) the electric field-induced increments of both the internal energy and the entropy exhibit a critical-like temperature dependence in the vicinity of transition from the isotropic liquid to the nematic phase. As a most important pretransitional effect, it is shown that at a temperature of about 10 degrees before the phase transition, an electric field applied to the isotropic liquids induces an increase in the entropy (Δ S>0) instead of its decrease, as observed far from the phase transition or for the non-mesogenic dipolar liquids.
Źródło:
Acta Physica Polonica A; 2007, 111, 6; 877-884
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dielectric Relaxation of 4-Cyanophenyl 4-n-Decyloxybenzoate in the Isotropic, Nematic, and Smectic A Phases
Autorzy:
Ginovska, M.
Czechowski, G.
Andonovski, A.
Jadżyn, J.
Powiązania:
https://bibliotekanauki.pl/articles/2014555.pdf
Data publikacji:
2000-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Md
77.84.Nh
77.22.Gm
Opis:
The paper presents the results of the dielectric relaxation study performed for the isotropic, nematic, and smectic A phases of 4-cyanophenyl 4'-n-decyloxybenzoate (C$\text{}_{10}$H$\text{}_{21}$O-Ph-COO-Ph-C≡ N, CP10DB) in the frequency range from 100 kHz to 100 MHz. In the nematic and smectic A phases the permittivity was measured with the probing electric field E parallel to the macroscopic molecular orientation (the director n). The recorded dielectric spectra correspond to the rotation of CP10DB molecules around the short axis and can be quite well described in the framework of the Debye model. It was found that the values of the activation energy for the molecular reorientations in the isotropic and smectic A phases of CP10DB are quite close to each other, whereas in the nematic phase the energy is remarkably higher.
Źródło:
Acta Physica Polonica A; 2000, 98, 6; 715-720
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamics of Nematogenic Molecules with Transverse Component of Dipole Moment
Autorzy:
Douali, R.
Czechowski, G.
Legrand, Ch.
Jadżyn, J.
Powiązania:
https://bibliotekanauki.pl/articles/2037273.pdf
Data publikacji:
2004-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Md
77.84.Nh
77.22.Gm
Opis:
The paper presents the results of studies of the dielectric relaxation of nematic 4'-butyloxy-3-fluoro- 4-isothiocyanatotolane, performed for different values of the angle between the probing electric field E and the macroscopic orientation of the sample (the director n) forced by the magnetic field B. Due to a relatively large transverse component of the dipole moment of 4'-butyloxy- 3-fluoro-4-isothiocyanatotolane, the studies allowed one to interpret consistently the dielectric relaxation spectra connected with the molecular rotation around the long axis.
Źródło:
Acta Physica Polonica A; 2004, 105, 4; 365-371
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dielectric Relaxation in Hydrogen Bonded Urea-Based Supramolecular Polymer N,N-di(2,2-dipentylheptyl)urea
Autorzy:
Jadżyn, J.
Bouteiller, L.
Déjardin, J.-L.
Czechowski, G.
Powiązania:
https://bibliotekanauki.pl/articles/2047092.pdf
Data publikacji:
2006-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.82.Pv
77.22.Gm
81.16.Fg
82.30.Rs
Opis:
Results of the dielectric relaxation studies, performed for supramolecular polymer formed by N,N'-di(2,2-dipentylheptyl)urea dissolved in carbon tetrachloride, are presented. The measurements were done for N,N'-di(2,2-dipentylheptyl)urea concentration up to about 7% (in mole fraction) in the frequency region from 100 kHz to 100 MHz and at the temperatures from 5ºC to 50ºC. The analysis of the experimental data were performed with the Havriliak-Negami equation. In the studied range of N,N'-di(2,2-dipentylheptyl)urea concentration and temperature, the obtained values of exponentsα andβ of the Havriliak-Negami equation are equal to 0.9±0.1 and 0.7±0.1, respectively, showing an anomaly in the dielectric relaxation behavior close to the Davidson-Cole type. Two examples of the modeling of dielectric properties of the supramolecular polymer solutions were presented.
Źródło:
Acta Physica Polonica A; 2006, 110, 4; 495-504
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Molecular Dynamics of 4-(trans-4-n-Heptylcyclohexyl)- Isothiocyanatobenzene Studied with Dielectric Relaxation Spectroscopy
Autorzy:
Bauman, D.
Czechowski, G.
Jadżyn, J.
Legrand, C.
Douali, R.
Powiązania:
https://bibliotekanauki.pl/articles/2014055.pdf
Data publikacji:
2000-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Md
77.84.Nh
77.22.Gm
Opis:
Dielectric relaxation study was carried out for the nematic and isotropic phases of 4-(trans-4'-n- heptylcyclohexyl)isothiocyanatobenzene in the frequency range from 100 kHz to 1 GHz. In the nematic phase two relaxation processes were recorded for the electric permittivity component measured parallel to the molecular orientation (director n) and three relaxation processes - for the perpendicular permittivity component. The strength of the nematic potential and the nematic order parameter were estimated.
Źródło:
Acta Physica Polonica A; 2000, 98, 1-2; 71-81
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of Magnetic Fredericksz Transition in Ferronematics
Autorzy:
Kopčanský, P.
Koneracká, M.
Jadżyn, J.
Czechowski, G.
Żywucki, B.
Powiązania:
https://bibliotekanauki.pl/articles/1964799.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Md
61.30.Gd
Opis:
The magnetic Fredericksz transition in ferronematics (thermotropic nematic liquid crystals 7CB and MBBA combined with fine magnetic particles of a size 10 nm) as a function of concentration of magnetic particles was studied by using simple dielectric measurements. The increase of the threshold magnetic field is observed in 7CB based ferronematic while the decrease of threshold field in MBBA based ferronematic is observed when the concentration of magnetic particles is increased. Experimental results are discussed in the framework of Brochard, de Gennes and Burylov, Raikher theories.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 437-440
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anomalous Dielectric Relaxation in Binary Mixtures of Mesogenic Solvent/Non-Mesogenic Solute
Autorzy:
Jadżyn, J.
Bauman, D.
Déjardin, J. -L.
Ginovska, M.
Czechowski, G.
Powiązania:
https://bibliotekanauki.pl/articles/2043683.pdf
Data publikacji:
2005-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.30.Eb
64.70.Md
87.15.Nn
68.35.Rh
83.10.Mj
Opis:
Dielectric relaxation studies for mixtures of strongly polar and mesogenic n-heptylcyanobiphenyl with non-polar and non-mesogenic carbon tetrachloride (CCl$\text{}_{4}$) were performed. The absorption band broadening due to fractional diffusion was observed. A correlation between the non-mesogenic admixture concentration and the anomalous diffusion exponent was found.
Źródło:
Acta Physica Polonica A; 2005, 108, 3; 479-489
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dielectric and Optical Studies of Homologous Series of Bicyclo[2,2,2]octane Derivatives with -NCS Terminal Group
Autorzy:
Herba, H.
Żywucki, B.
Czechowski, G.
Bauman, D.
Wąsik, A.
Jadżyn, J.
Powiązania:
https://bibliotekanauki.pl/articles/1933452.pdf
Data publikacji:
1995-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.30.Gd
77.22.Ch
78.20.Fm
Opis:
The static dielectric constants and the optical birefringence for four members of the homologous series of bicyclo[2,2,2]octane derivatives with -NCS terminal group (pentyl to octyl) have been measured as a function of temperature. From the dielectric anisotropy, the optical birefringence as well as the polarized absorption spectra of the dichroic dye dissolved in the liquid crystalline host the order parameter has been determined. The results obtained by using various experimental methods have been compared with those calculated from the Maier-Saupe mean field theory. It has been found that the order parameter for the successive homologues shows alternation similar to that exhibited for the nematic-isotropic transition temperature.
Źródło:
Acta Physica Polonica A; 1995, 87, 6; 985-994
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The application of friction stir welding (FSW) of aluminium alloys in shipbuilding and railway industry
Autorzy:
Gesella, G.
Czechowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/245646.pdf
Data publikacji:
2017
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
Friction Stir Welding
FSW
aluminium alloys
welding
shipbuilding industry
mechanical properties
Opis:
The article describes possibilities of application of friction stir welding (FSW) in shipbuilding and railway industry. Actually, in these sectors of industry more and more often modern construction materials are used. The biggest restriction of implementing new materials is technological possibility of joining them. One of construction materials used in the shipbuilding is aluminum, mainly its alloy of 5xxx-aluminium-magnesium series. Its application is justified by good corrosion resistance in seawater and good mechanical attributes. Thanks to susceptibility to plastic treatment, one gains good mechanical attributes with thrice-smaller density than a density of steel, what causes triple reduction of weight of aluminum construction relative to steel one. Alloys of 5xxx series are well weldable. It is generally known that welding is not a good way to joint metals, especially the aluminum. The application of FSW with mixing allows one to change approach to production of aluminum constructions. Using aluminum plates prefabricated with FSW method allows one to reduce time needed for installation of construction and considerably decreases the production costs. The article describes technology and directions of development of friction welding of aluminum alloys of 5xxx series using FSW method. There is also shown analysis of its usefulness in ship and railway industry and comparison of mechanical attributes of weld made with electric arc using MIG (135), TIG (141) method and FSW method.
Źródło:
Journal of KONES; 2017, 24, 2; 85-90
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Data mining system for air quality monitoring networks
Autorzy:
Czechowski, P.
Badyda, A.
Majewski, G.
Powiązania:
https://bibliotekanauki.pl/articles/204820.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
air pollutants
data quality analysis
data mining
estimation
exploratory methods
harmonic
principal component analysis
statistical tests outliers
influential
leverage observations
analytical software system
programming
Eco Data Miner
EDM
Winsorized mean
Cook
Mahalanobis distance
DFITS
COVRATIO
Opis:
The use of quantitative methods, including stochastic and exploratory techniques in environmental studies does not seem to be sufficient in practical aspects. There is no comprehensive analytical system dedicated to this issue, as well as research regarding this subject. The aim of this study is to present the Eco Data Miner system, its idea, construction and implementation possibility to the existing environmental information systems. The methodological emphasis was placed on the one-dimensional data quality assessment issue in terms of using the proposed QAAH1 method - using harmonic model and robust estimators beside the classical tests of outlier values with their iterative expansions. The results received demonstrate both the complementarity of proposed classical methods solution as well as the fact that they allow for extending the range of applications significantly. The practical usefulness is also highly significant due to the high effectiveness and numerical efficiency as well as simplicity of using this new tool.
Źródło:
Archives of Environmental Protection; 2013, 39, 4; 123-147
2083-4772
2083-4810
Pojawia się w:
Archives of Environmental Protection
Dostawca treści:
Biblioteka Nauki
Artykuł

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