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Wyszukujesz frazę "Hamada, E." wg kryterium: Autor


Wyświetlanie 1-6 z 6
Tytuł:
The Effect of Visible Light Irradiation on Positronium Formation in Polyethylene at Low Temperature
Autorzy:
Ito, Y.
Hirade, T.
Hamada, E.
Suzuki, T.
Powiązania:
https://bibliotekanauki.pl/articles/2007996.pdf
Data publikacji:
1999-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
Opis:
The effect of visible light exposing on the ortho-positronium formation in polyethylene was studied. Lifetime spectra of positrons in polyethylene were measured in the temperature range between 50 K and 370 K. It was observed that the visible light quenches the enhancement of ortho-positronium intensity (I$\text{}_{3}$) at lower temperature than ca. 250 K - the glass transition temperature of polyethylene. On the other hand, the lifetime of ortho-positronium component (τ$\text{}_{3}$) was not affected by the presence of the visible light.
Źródło:
Acta Physica Polonica A; 1999, 95, 4; 533-538
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positron Irradiation Effects on Positronium Formation in Polycarbonate Sduring a Positron-Annihilation Experiment
Autorzy:
Suzuki, T.
Kondo, K.
Hamada, E.
Ito, Y.
Powiązania:
https://bibliotekanauki.pl/articles/2025767.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
Opis:
The positron-irradiation effect on polycarbonate during a positron-annihilation lifetime spectroscopy experiment was investigated using different intensities of $\text{}^{22}$Na positron sources andγ-irradiated samples. The decrease in I$\text{}_{3}$ was larger for a larger intensity of positron sources. In the case of a weak source (≈ 140 kBq), I$\text{}_{3}$ did not change with the elapsed time for non-irradiated samples. However, for 1 MGy irradiated samples, I$\text{}_{3}$ measured with the weak source increased with the elapsed time. This can be attributed to a decrease in the radicals induced in the irradiated samples by γ-irradiation. In order to explain the change in I$\text{}_{3}$ measured at room and liquid-nitrogen temperatures, several effects, such as radicals, cross-linking, structure change, and charging, need to be considered. Also, it is difficult to explain the change in I$\text{}_{3}$ using only one of these effects.
Źródło:
Acta Physica Polonica A; 2001, 99, 3-4; 515-521
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of a Pulsed Slow-Positron Beam to Low-Density Polyethylene Film
Autorzy:
Hamada, E.
Oshima, N.
Katoh, K.
Suzuki, T.
Kobayashi, H.
Kondo, K.
Kanazawa, I.
Ito, Y.
Powiązania:
https://bibliotekanauki.pl/articles/2024257.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
Opis:
A pulsing system for a slow-positron beam was applied to study the region near the surface of low-density polyethylene film using positron-annihilation lifetime measurement. The lifetime and intensity of ortho-positronium near the surface were measured as a function of the incident positron energy (1.6-9.1 keV). The size of intermolecular spaces in the surface region (~ 1500 nm) was larger than that in the bulk region. This tendency was especially strong in the region around 200 nm below the surface. On the other hand, the intensity of ortho-positronium decreased at lower incident positron energies, which was attributed to a decrease in the density of the spur electrons and/or an increase in the number of reemitted positrons from the surface.
Źródło:
Acta Physica Polonica A; 2001, 99, 3-4; 373-378
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mirror surface finishing of hardened die steel by high-Power ultrasonic elliptical vibration cutting
Autorzy:
Jung, H.
Shamoto, E.
Ueyama, T.
Hamada, S.
Xu, L.
Powiązania:
https://bibliotekanauki.pl/articles/100101.pdf
Data publikacji:
2016
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
elliptical vibration cutting
mirror surface finishing
hardened steel
Opis:
Ultrasonic elliptical vibration cutting has recently been utilized in industry for finishing of various precision parts such as mirror surface finishing and precision micro machining of dies and molds. However, its application has been limited to high-cost ultra-precision machining, where depth of cut is typically in a range from a few micrometers to several tens of micrometers due to power limitation of the vibration device. To expand its application to low-cost mirror surface finishing with ordinary machining facilities, a high-power elliptical vibration device was developed in this research. The elliptical vibration cutting of hardened die steel was examined by applying the developed high-power elliptical vibration device with single crystalline diamond tools. Pick feed was kept to be 0.02 mm to obtain mirror quality surfaces, while depth of cut was increased up to 0.4 mm to verify performance of the high-power elliptical vibration cutting. By analyzing the experimental results, it was clarified that mirror surface finishing of the hardened die steel can be achieved at the large depth of cut with practically acceptable tool life.
Źródło:
Journal of Machine Engineering; 2016, 16, 1; 5-14
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A comparative study on the performance of radiation detectors from the HgI2 crystals grown by different techniques
Autorzy:
Martins, J. F. T.
Costa, F. E.
dos Santos, R. A.
de Mesquita, C. H.
Hamada, M. M.
Powiązania:
https://bibliotekanauki.pl/articles/146916.pdf
Data publikacji:
2012
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
crystal growth
iodide mercury crystal
physical vapor transport (PVT)
radiation detector
semiconductor crystal
Opis:
In this work, the establishment of a technology for HgI2 purification and crystal growth is described, aiming at a future application of this crystal as a room temperature radiation semiconductor detector. Two methods of crystal growth were studied in the development of this work: (1) physical vapor transport (PVT) and (2) saturated solution from dimethylsulphoxide (DMSO) complexes. In order to evaluate the crystals obtained using each of these methods, systematic measurements were carried out for determining the stoichiometry, structure, orientation, surface morphology and impurity of the crystal. The influence of these physicochemical properties of the crystals developed was evaluated in terms of their performance as a radiation detector. The best response to radiation was found for the crystals grown by the PVT technique. Significant improvement in the performance of HgI2 radiation detector was found, purifying the crystal by means of two successive growths by the PVT technique.
Źródło:
Nukleonika; 2012, 57, 4; 555-562
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Gamma-ray computed tomography SCANNERS for applications in multiphase system COLUMNs
Autorzy:
Calvo, W. A. P.
Hamada, M. M.
Sprenger, F. E.
Vasquez, P. A. S.
Rela, P. R.
Martins, J. F. T.
de Matos Pereira, J. C. S.
Omi, N.
de Mesquita, C. H.
Powiązania:
https://bibliotekanauki.pl/articles/148082.pdf
Data publikacji:
2009
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
industrial computed tomography
multiphase flow systems
non-destructive testing
gas absorption column
industrial process optimization
packed distillation columns
scanning systems
Opis:
Gamma-ray tomography experiments have been carried out to detect spatial patterns in the porosity, in a 0.27 m diameter packed steel column using a first generation computed tomography (CT) system. The CT scanner consists of a NaI(Tl) detector 5.08 cm in diameter, and an encapsulated 137Cs (3.7 GBq) radioactive source, located opposite to the center of the detector. The detector and the source, mounted on a fixed support and the column, can rotated and dislocate by two stepping motors controlled through a microprocessor. Different sizes of stainless steel Raschig rings (12.6, 37.9 and 76 mm) have been examined. The primary objective of this work is to detect spatial patterns and statistical information on porosity variation in packed distillation columns. Horizontal scans, at different vertical positions of the packed bed were made for each size of Raschig rings. Radial porosity variation within the packed bed has been determined. This study has demonstrated that the porosity and its spatial distribution in a metallic packed column can be measured with adequate spatial resolution using the gamma-ray tomography technique. After validation of this first generation CT, the turntable design to rotate and dislocate the 60Co or 137Cs sealed gamma-ray sources and multidetector array for the third generation industrial computed tomography was also developed.
Źródło:
Nukleonika; 2009, 54, 2; 129-133
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-6 z 6

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