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Wyświetlanie 1-10 z 63
Tytuł:
Analytical forms of deuteron wave function and density distribution
Autorzy:
Zhaba, V. I.
Powiązania:
https://bibliotekanauki.pl/articles/1177883.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
analytic form
approximation
density distribution
deuteron
transition density
wave function
Opis:
Values of density distribution and transition density are calculated using the obtained coefficients of four deuteron wave function for analytical forms in coordinate representation for Argonne v18 potential. Calculations of these values can serve for an assessment of a correctness and accuracy of choice of an analytical form at concrete approximation of radial deuteron wave function. Also these calculations help to evaluate information on such characteristics of a deuteron as a charge form factor, tensor polarization and momentum distribution.
Źródło:
World Scientific News; 2018, 98; 206-213
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Modified Penetration Model for Copper-Tungsten Shaped Charge Jets with Non-uniform Density Distribution
Autorzy:
Elshenawy, T.
Elbeih, A.
Li, Q. M.
Powiązania:
https://bibliotekanauki.pl/articles/358894.pdf
Data publikacji:
2016
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
shaped charge
jet penetration
virtual origin
non-uniform density distribution
Opis:
The penetration of a shaped charge jet with non-uniform density distribution was studied. The virtual origin model, which assumes a constant jet density, was modified to include the situation where the jet density deficit/reduction of an un-sintered copper-tungsten powder jet causes a non-uniform jet density distribution. A relation between the relative density ratio and the normalised jet velocity is proposed, based on which an analytical solution of the modified virtual origin model is obtained. The validity of the modified virtual origin model was demonstrated by its largely improved prediction in comparison with experimental and numerical results. It showed that the density reduction term reduces the penetration depth by 16.58% for an un-sintered copper-tungsten powder jet.
Źródło:
Central European Journal of Energetic Materials; 2016, 13, 4; 927-943
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dry beneficiation and cleaning of chinese high-ash coarse coal utilizing a dense-medium gas-solid fluidized bed separator
Autorzy:
He, J.
Tan, M.
Zhu, R.
Luo, Z.
Powiązania:
https://bibliotekanauki.pl/articles/110808.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
coal cleaning
dense-medium fluidized bed
density distribution
segregation
separation performance
Opis:
Dry dense-medium fluidized bed separation provides a new alternative approach for coal beneficiation and cleaning. An indicator of segregation degree Sash was proposed to evaluate the stratified performance of coal samples by bed density. Fluidization stability of the bed was greatly enhanced by mixing a certain amount (21.53%) of fine magnetite powder (< 0.15 mm) into the fluidized media, which indicated a uniform density distribution as well as slight fluctuations in bed. It was found that the favorable density-segregation performance of 3–13 mm coarse coal occurred with a static bed height of 80 mm and a superficial gas velocity of 11.84 cm/s. The optimal segregation degree values of 0.67, 0.74 and 0.76 were obtained for 3–6, 6–10 and 10–13 mm coal samples, respectively. Low-ash clean coal with yields of 50.79, 56.83 and 61.24% were effectively acquired by the dry separation for various coal size fractions, respectively. Probable error values of 0.07, 0.055 and 0.05 g/cm3 were achieved, indicating good separation performance.
Źródło:
Physicochemical Problems of Mineral Processing; 2016, 52, 2; 662-675
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Coronal Electron Density Distribution Estimated from Meter Type II Radio Bursts and Coronal Mass Ejections
Autorzy:
Yusof, N. S.
Hamidi, Z. S.
Norsham, N. A.
Jafni, A. I.
Kahlid, N. M.
Hamdan, M. N.
Kamaruddin, Farahana
Tahar, Muhammad Redzuan
Monstein, C.
Shariff, N. N. M.
Powiązania:
https://bibliotekanauki.pl/articles/1192681.pdf
Data publikacji:
2016
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
coronal mass ejection
Type II radio burst
electron density distribution
e-CALLISTO
Opis:
In this paper, we investigate the characteristic coronal mass ejection and Type II radio burst, we calculated the drift rate of Type II Radio burst and determined the electron density distribution from a Coronal Mass Ejections. The data were taken from website e-CALLISTO, Space Weather, SolarHam and also from the Langkawi National Observatory, National Space Agency, Langkawi Kedah, Malaysia. All the data collected on 15th March 2015, 4th November 2015 and 16th December 2015. On 16 March 2015, the events were associated with slower C9 solar flare and CME. For this week, the events were causing radio blackouts on Earth. On 4 November 2015, the events were associated with M1.9 solar flare, CME and Solar burst Type II. The value of the solar wind was 570.4 km/Sec and value for radio sun was 124 sfu. For drift rate, we calculated the value for sites in Sri Lanka (ACCIMT-SRI), Ooty, India (OOTY), Indonesia (INDONESIA) and Kasi, South Korea (KASI) at between 0324 to 0328 UTC. In South Korea was highest drift rate, which is 1.397 MHz/s. Also, at HB9SCT, Switzerland (HB9SCT), Humain, Belgium (Humain), Daro, Germany (Daro-VHF) and TCD in Birr, Ireland (BIR), we calculated the drift rate of solar burst Type II between 1200 until 1203 UTC. In Belgium had the highest value of the drift rate to compare at other sites. Harmonic pattern was also appeared for all these sites. On 16th December 2015, this event associated with C6.6 solar flare and CME. These events give an impact on the earth geomagnetic field which is formed of aurora because of the combination of both events that trigger geomagnetic storming.
Źródło:
World Scientific News; 2016, 46; 19-35
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of coal mineral matter liberation efficiency index
Ocena stopnia uwolnienia frakcji mineralnej węgla
Autorzy:
Surowiak, A.
Powiązania:
https://bibliotekanauki.pl/articles/319165.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
liberation efficiency
hard coal
particle size distribution
particle density distribution
stopień uwolnienia
węgiel kamienny
skład ziarnowy
skład densymetryczny
Opis:
The main tool allowing to forecast effects of gravitational beneficiation of hard coals is density analysis. The obtained results of such analysis should show real minerals liberation level in connection with their physical properties. In purpose of calculating mineral phase liberation from hard coal the size and density analysis was performed for raw hard coal which was feed directed to mineral processing. For each obtained size-density fraction its yield and ash contents were determined. The Hall’s separation curve was used in the paper to evaluate liberation efficiency of mineral phase from hard coal. The advantage of this curve is the fact that it is possible to describe it mathematically by means of hyperbolic equation. It was stated that if particle size is lower the liberation level of mineral substance grows.
Podstawowym narzędziem pozwalającym prognozować efekty wzbogacania grawitacyjnego węgli kamiennych jest analiza densymetryczna. W związku z tym otrzymane wyniki takiej analizy powinny odzwierciedlać rzeczywisty stopień uwolnienia minerałów w powiązaniu z ich właściwości fizycznymi. W celu wyliczenia uwolnienia fazy mineralnej z węgla kamiennego wykonano analizę granulometryczną i densymetryczną surowego węgla kamiennego – nadawy kierowanej do przeróbki mechanicznej. W otrzymanych klaso-frakcjach wyliczono wychody oraz oznaczono zawartość popiołu. W artykule wykorzystano krzywą separacji Halla do oceny stopnia uwolnienia frakcji mineralnej z węgla kamiennego. Zaletą krzywej separacji Halla jest to, że można ją opisać w sposób matematyczny przy pomocy równania hiperboli. Stwierdzono, że ze wraz z zmniejszaniem się wielkości ziaren wzrasta stopień uwolnienia substancji mineralnej.
Źródło:
Inżynieria Mineralna; 2013, R. 14, nr 2, 2; 153-158
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A method for the determination of spatial electron density distribution in great Plasma-Focus devices
Autorzy:
Kasperczuk, A.
Paduch, M.
Pisarczyk, T.
Tomaszewski, K.
Powiązania:
https://bibliotekanauki.pl/articles/147148.pdf
Data publikacji:
2002
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
bremsstrahlung radiation
electron density distribution
frame optical camera
plasma-focus device
plasma radiation intensity
shadowgraphy
Opis:
Determination of the electron density of plasma generated in a great plasma-focus device by means of interferometry is very difficult or sometimes impossible. In order to determine spatial electron density distributions of plasma in a PF-1000 device, a special method was prepared, with the use of plasma images obtained by means of both an optical frame camera and shadowgraphy. Analysis of plasma radiation in the very narrow Äë = 60 Ĺ optical range allowed us to determine the relation between intensity of the plasma radiation and the electron density. It was also shown that the influence of electron temperature on plasma radiation is not large. The presented method allowed us to obtain spatial electron density distributions of plasma (in relative units) in the PF-1000 device. By means of this method a number of important information about the plasma-focus phenomenon was obtained.
Źródło:
Nukleonika; 2002, 47, 1; 23-26
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Xe and Kr bonding abilities in the single crystal oxygen vacancies of the uranium based fuel
Autorzy:
Dąbrowski, L.
Szuta, M.
Powiązania:
https://bibliotekanauki.pl/articles/147880.pdf
Data publikacji:
2012
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
noble gases
chemical bond
UO2 single crystal
valence electron density distribution
atomic force constants
bond energy
crystal lattice
Opis:
The valence electron density distribution of krypton and xenon located in the oxygen vacancy and in its nearest neighbourhood was performed by application of the method “ab initio”. The results are presented on the graphs. The bonding energies of krypton and xenon in the uranium dioxide crystal lattice were calculated. It was found also that krypton and xenon cause a local increase of UO1.75Xe0.25 and UO1.75Kr0.25 unit cell and cause its deformation what is presented in tables. The force constants of krypton and xenon were also assigned what gives evidence about the strong bond of krypton and xenon with the UO1.75Xe0.25 and UO1.75Kr0.25 single crystal lattice. Obtained results are compared with the analogical studies of He atom incorporation into UO2 single crystal lattice.
Źródło:
Nukleonika; 2012, 57, 1; 95-100
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Binary Classification of Heart Failures Using k-NN with Various Distance Metrics
Autorzy:
Udovychenko, Y.
Popov, A.
Chaikovsky, I.
Powiązania:
https://bibliotekanauki.pl/articles/226330.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
magnetocardiography
current density imaging
current density distribution map
k-NN classification
negative Tpeak
heart failure diagnostics
Mahalanobis distance
Cityblock distance
Eucleadian distance
Chebyshev distance
Opis:
Magnetocardiography is a sensitive technique of measuring low magnetic fields generated by heart functioning, which is used for diagnostics of large number of cardiovascular diseases. In this paper, k-nearest neighbor (k-NN) technique is used for binary classification of myocardium current density distribution maps (CDDM) from patients with negative T-peak, male and female patients with microvessels (diffuse) abnormalities and sportsmen, which are compared with normal control subjects. Number of neighbors for k-NN classifier was selected to obtain highest classification characteristics. Specificity, accuracy, precision and sensitivity of classification as functions of number of neighbors in k-NN are obtained for classification with several distance measures: Mahalanobis, Cityblock, Eucleadian and Chebyshev. Increase of the accuracy of classification for all groups up to 10% was obtained using Cityblock distance metric in binary k-NN classifier with 19 - 27 neighbors, comparing to other metrics. Obtained results are acceptable for further patient’s state evaluation.
Źródło:
International Journal of Electronics and Telecommunications; 2015, 61, 4; 339-344
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badania rozkładu gęstości elektronowej w kryształach, czyli jak zobaczyć szczegóły struktury elektronowej cząsteczek
Electron density distribution in crystals or how to see the details of the electronic structure of molecules
Autorzy:
Kubicki, M.
Powiązania:
https://bibliotekanauki.pl/articles/171566.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
rozkład gęstości elektronowej
model multipolowy
oddziaływania międzycząsteczkowe
pochodne 4-nitroimidazolu
electron density distribution
multipolar model
intermolecular interactions
4-nitroimidazole derivatives
Opis:
X-ray structural analysis might be regarded as a method of visualizing molecules as they appear in the crystals. The model, which is conventionally and universally used in this method, the Independent Atom Model (IAM) assumes that the electron density distribution, which scatters the X-rays is built of the spherically-symmetrical, neutral atoms. This model is responsible for the unprecedented success of X-ray structural analysis, which reflects in about one million crystal structures (i.e. the sets coordinates of the atoms constituting the molecules) deposited in the various databanks (cf. Fig. 1), and in the speed and accuracy which the method has reached. In principle, in few hours one can get the complete information about the crystal structure. But this success is accompanied by negligence of the scientific virtue hidden beyond the IAM. In fact, it was known from the very beginning of the X-ray diffraction studies by von Laue and Braggs, that some fine details of the electron density distribution should be available. The technological advance (four-circle diffractometers, powerful X-ray sources, fast computers etc.) caused that in 1960’s the time was ripe for the development of the experimental studies of details of electron density distribution in the crystals, beyond the IAM. The early experiments by Coppens and co-workers proved that this information – about the electron density transferred to the covalent bonds, lone pairs, even intermolecular interactions – can actually be obtained and analyzed (Fig. 2). The need for the model which could be used in the least-squares procedure led to the formulation of so-called pseudoatom models, including the most popular till now, Hansen-Coppens model (eq. 2) in which the aspherical part is described in terms of real spherical harmonics. In this paper, the basics of the electron density studies is described in some detail, including the step-by-step description of a typical procedure from the experiment to the final steps of refinement. An example of the analysis of the high-resolution structure of 1,2-dimethyl-4-nitro-5-morpholine-imidazole hydrate is used to show an application of this method in studying the intermolecular interactions, including weak C-H···O and C-H···N hydrogen bonds. It is shown that the multipolar model is able to deliver more informations than the promolecular model with spherically symmetrical electron distributions.
Źródło:
Wiadomości Chemiczne; 2014, 68, 5-6; 403-427
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Symulacyjna analiza losowych błędów estymacji czasu opóźnienia przy zastosowaniu metody korelacyjnej i fazowej
Simulation analysis of random errors of time delay estimation by cross-correlation and phase methods
Autorzy:
Hanus, R.
Petryka, L.
Zych, M.
Powiązania:
https://bibliotekanauki.pl/articles/157098.pdf
Data publikacji:
2008
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
estymacja czasu opóźnienia
funkcja korelacji wzajemnej
faza wzajemnej gęstości widmowej mocy
błędy statystyczne
time delay estimation
cross-correlation analysis
phase of power density distribution
statistical errors
Opis:
W artykule przedstawiono wyniki analizy porównawczej losowych błędów estymacji czasu opóźnienia otrzymanego z funkcji korelacji wzajemnej i fazy wzajemnej gęstości widmowej mocy. Przeprowadzone symulacje wykazały, że dla małych wartości stosunku sygnał/szum (SNR) mniejsze wartości błędów uzyskuje się dla metody korelacyjnej. Metoda fazowa jest natomiast bardziej efektywna dla dużych wartości SNR, a jej zaletą jest możliwość wyznaczenia opóźnienia dla wybranych harmonicznych.
The paper presents results of the comparative analysis of random errors of the time delay estimation (TDE) by means of the cross-correlation analysis and the phase of power density distribution. The simulations performed show that for the low level of signal-to-noise-ratio (SNR) the statistical errors of TDE obtained from the cross-correlation analysis are smaller than those from the phase method. However, the latter one is more efficient for higher SNR than the cross- correlation and can be applied to any selected harmonics.
Źródło:
Pomiary Automatyka Kontrola; 2008, R. 54, nr 12, 12; 860-862
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-10 z 63

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