Wyniki wyszukiwania - Biblioteka Nauki

1

Radiation interaction on forced and free convection across a horizontal cylinder

100%

Hossain M. A. , Kutubuddin M. , Takhar H. S.

Applied Mechanics and Engineering

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1999

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tom Vol. 4, no 2

219-235

EN

An analysis is performed to study the flow and heat transfer characteristics of laminar combined forced and free convection, with the effects of radiation, of a viscous incompressible and optically dense fluid from a horizontal cylinder. The transformed convection equations of non-similar boundary layers obtained for both the forced convection flow and the natural convection flow dominated regimes are solved by the implicit finite difference method. Numerical results are obtained for different physical parameters, such as the Rosseland parameter, Rd and the surface temperature parameter, __ , for fluids having the Prandtl number of 0.7. Results are presented in terms of local skin-friction and the local Nusselt number against the angular displacement, _ ,as well as the buoyancy parameter, __ . It is observed that both the local shear and the Nusselt number increase due to an increase in the values of Rd and __ , in the entire pure forced to pure free convection regimes.

2

Electron radiation effects on RuO2-based thick-film temperature sensors

100%

Mleczko K. , Zawislak Z. , Kolek A. , Danilchenko B. , Voitsihovska O.

Optica Applicata

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2011

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tom Vol. 41, nr 2

455--462

EN

The paper discusses the effects of electron radiation on resistance type Ru-based thick-film temperature sensors. Specimens, both commercial and lab made, were irradiated by the electron beam of the fluence from 5×1015 to 5×1017 e/cm2. R vs. T characteristics were measured from 4 to 300 K before irradiation and after each radiation dose. Measurements show that sensors containing a higher amount of metallic phase (lower resistance) are more immune to radiation. This statement concerns also low frequency noise which was observed to increase less for low-resistance samples. Our conclusion is that the application of Ru-based temperature sensors in the radiation environment is limited to the low temperature region - below 20…25 K.

3

Radiation activities and application of ionizing radiation on cultural heritage at ENEA Calliope gamma facility (Casaccia R.C., Rome, Italy)

88%

Baccaro S. , Cemmi A.

Nukleonika

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2017

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tom Vol. 62, No. 4

261--267

EN

Since the 1980s, research and qualification activities are being carried out at the 60Co gamma Calliope plant, a pool-type irradiation facility located at the Research Centre ENEA-Casaccia (Rome, Italy). The Calliope facility is deeply involved in radiation processing research and on the evaluation and characterization of the effects induced by gamma radiation on materials for different applications (crystals, glasses, optical fibres, polymers and biological systems) and on devices to be used in hostile radiation environment such as nuclear plants, aerospace and high energy physics experiments. All the activities are carried out in the framework of international projects and collaboration with industries and research institutions. In the present work, particular attention will be paid to the cultural heritage activities performed at the Calliope facility, focused on two different aspects: (a) conservation and preservation by bio-deteriogen eradication in archived materials, and (b) consolidation and protection by degraded wooden and stone porous artefacts consolidation.

4

Radiation and thermal diffusion effects on MHD unsteady Maxwell fluid past a porous flat through porous medium

75%

Eldabe N. T. M. , Hassan A. A. A. , Ghaly A. Y.

Mechanics and Mechanical Engineering

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2004

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tom Vol. 7, nr 2

153-163

EN

Radiation and thermal diffusion effects of magnetohydrodynamic flow for non Newtonian fluid through a porous medium past an infinite porous flat plate arc presented. The flow under consideration obeys Maxwell rheological model. Solutions for velocity, temperature and concentration distributions arc obtained with the help of finite difference method. The effects of various parameters such as relaxation parameter λ of the Maxwell fluid, permeability of the fluid K, magnetic parameter M, Dufour number Df, Soret number Sr, Prandtl number Pr, radiation parameter N and Schmidt number Sc on the velocity, temperature and concentration profiles are studied and illustrated graphically. We obtained also the rate of heat transfer and concentration gradient during the course of discussion.

5

Evaluation of internal exposure of nuclear medicine staff working with radioiodine in Poland

75%

Krajewska G. , Krajewski P.

International Journal of Occupational Medicine and Environmental Health

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2023

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tom 36

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nr 5

587-595

EN

The iodine-131 (I-131) content in the thyroid of staff members working with this radionuclides has been measured with about 500 employees in about 25 hospital’s departments of nuclear medicine performing therapy and diagnosis of thyroid disease in Poland. The measurements were performed with portable detection unit for in situ measurements of radioiodine. This is consist with scintillation detector sodium iodine activated by thallium (NaI(Tl)) – battery-powered and portable tube base Multichannel Analyzer Canberra UniSPEC. Based on direct measurements of the iodine content, the effective dose equivalent for workers due to inhalation of I-131 was estimated. All individuals actively working with iodine show measurable amounts of this isotopes in their thyroids. The average measured activity in the thyroid of the nuclear medicine staff was found to be equal at average 550 Bq within the range 70 Bq–2.5 kBq. There is no apparent correlation between the measured I-131 levels and risk categories. Nevertheless the technical and nuclear medicine staff show higher I-131 thyroid level comparing to hospital services staff. Calculated maximum committed effective dose for particular exposed person is <10% of 20 mSv/year.

6

Facile microwave-assisted synthesis of Al:Mn co-doped PbI2 nanosheets: structural, vibrational, morphological, dielectric and radiation activity studies

75%

Yahia I. S. , Shkir M. , Ganesh V. , Abutalib M. M. , Zahran H. Y. , Alfaify S.

Materials Science Poland

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2018

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tom Vol. 36, No. 2

320--326

EN

Herein, we report a successful development of nano-scale pure and Al and Mn co-doped PbI2 using facile microwave-assisted route. Structural study was done through X-ray diffraction analysis of grain size, dislocation density and lattice strain. The crystallite size was found to vary from 28 nm to 40 nm due to Al:Mn co-doping in PbI2. The presence of various vibrational modes was confirmed by FT-IR spectroscopy and red shifting was observed in peak positions compared to the bulk. Surface morphology, examined using a scanning electron microscope, confirmed the formation of single crystal nanosheets of a thickness in the range of 10 nm to 30 nm. The single crystal nanosheets were found to be transformed to large area nanosheets due to the doping. Enhancement in dielectric constant from ~7.5 to 11 was observed with increasing Al doping concentration. Linear attenuation coefficient was calculated and showed the enhancement of blocking gamma rays with increasing doping concentration. Its value was found to increase from 7.5 to 12.8 with the doping. The results suggest that the synthesized nanostructures can be used for detection and absorption of gamma rays emitted by 137Cs and 241Am sources.