[en] Theoretical M-shell X-ray production cross sections have been calculated within the ECPSSR model. The semi-empirical cross sections are then deduced by fitting the available experimental data normalized to their corresponding theoretical values for elements with 72≤ Z ≤ 90 by proton in the energy range 0.1-4.0 MeV. Also, an analytical formula has been used to calculate the empirical X-ray production cross sections by direct fitting of the same experimental data, which are found to be universal, both for individual and collective fits. On the other hand, based on the individual fitting which gives the reliable cross sections, we attempt to deduce another new empirical cross sections by assuming that the ratio empirical to ECPSSR of the cross sections is roughly the same for all elements. In addition, our results are presented for selected heavy elements, namely ₇₄W, ₇₉Au and ₈₃Bi, being the most extensively studied. Finally, a comparison is made between the different procedures followed here and the experimental data

[en] Resistance to corrosion of metals the surface of which is modified by ion implantation has been the subject of many papers. We present here a literature survey concerning research works done on ion implantation on iron, unalloyed or low alloyed steels, and stainless steels. Papers reporting works on nitrogen implantation on the same alloys are more particularly discussed. 53 refs

[en] Experimental ionization cross sections for K-shell by protons for elements from Be to U available in the literature from 1953 to 1999 are fitted to deduce the empirical K-shell ionization cross sections, 5400 values of cross sections have been collected from various references. The deduced empirical cross sections are compared to the experimental data and to the theoretical values obtained by our research group within the ECPSSR theory and also with the reference ionization cross sections obtained by Paul and Sacher [H. Paul and J. Sacher At. Data. Nucl. Data. Tables 42 (1989) 105]

[en] We present in this contribution theoretical predictions of the L _i (i 1, 2, 3) subshells ionization cross sections within the ECPSSR theory for elements with atomic number 71 Z 80 for protons with energy of 0.5 to 3.0 MeV. These predictions are compared to the experimental data reported by Orlic et al. [At. Data Nucl. Data Tables 56 (1994) 159] and by Sokhi and Crumpton [At. Data Nucl. Data Tables 30 (1984) 49] by plotting the ratio S σ _exp/σ _ECPSSR as a function of the reduced velocity parameter for each individual subshell L1, L2 and L3. By fitting separately the ratio S, we deduced reference ionization cross sections for each Li subshell. On the other hand, we report empirical ionization cross sections and make a comparison between the reference cross sections, the empirical cross sections reported in this paper and those reported by Sow et al. [Nucl. Instr. and Meth. B 75 (1993) 58] and by Orlic et al. [Int. J. PIXE 4 (4) (1994) 217]

[en] We present in this contribution, semi-empirical production cross sections of the main X-ray lines Lα, Lβ and Lγ for elements from Sn to U and for protons with energies varying from 0.5 to 3.0 MeV. The theoretical X-ray production cross sections are firstly calculated from the theoretical ionization cross sections of the Li (i = 1, 2, 3) subshell within the ECPSSR theory. The semi-empirical Lα, Lβ and Lγ cross sections are then deduced by fitting the available experimental data normalized to their corresponding theoretical values and give the better representation of the experimental data in some cases. On the other hand, the experimental data are directly fitted to deduce the empirical L X-ray production cross sections. A comparison is made between the semi-empirical cross sections, the empirical cross sections reported in this work and the empirical ones reported by Reis and Jesus [M.A. Reis, A.P. Jesus, Atom. Data Nucl. Data Tables 63 (1996) 1] and those of Strivay and Weber [Strivay, G. Weber, Nucl. Instr. and Meth. B 190 (2002) 112]

[en] A general class of potentials covering the Poschl-Teller-type and Scarf-type is considered. The analytical expression of the energy eigenvalues is established with the help of the exact quantization formula. Then, using appropriate coordinate transformations, the exact spectrums of five well-known potentials: Poschl-Teller, Poschl-Teller I and Poschl-Teller II, Scarf I, and Scarf II, are deduced in a simple way. (author)

[en] Highlights: • The study analyzes the performance of generator air coolers for a hydro-power plant. • The study investigates the effects of cooler design, time variation, and locations. • Malfunction of some coolers is equivalent to reduction in the heat transfer area. • The original coolers suffer from permanent fouling due to corrosion and erosion. • Effectiveness for both cooler designs agrees with those obtained empirically. -- Abstract: The present research study was carried out on the performance of generator air coolers for the hydro-power plant of Aswan High Dam at Egypt. The study is carried out under varying operating conditions associated with diurnal variations of the generation from power units and with the place that air-water coolers are located. Air temperatures and cooling water pressures were measured together with recording the generated power so that investigating the performance characteristics of the original and new air coolers. Both coolers were designed with excess surface area enabling the coolers to work well for long periods under dirt conditions. The effectiveness values for both cooler designs were in good agreement with those obtained by the related previous research works at the same flow condition. The maximum and minimum values of the actual fouling factor for both coolers give representative average values for the original cooler twice those representative average values for the new cooler. Also, the malfunction of some original coolers was equivalent to the reduction in the heat transfer area. The hot air temperatures showed good uniformity indicating good flow behaviour of the circulating air so that satisfying the normal design temperature range.

[en] Within the individual treatment of the elements from beryllium (₄Be) to uranium (₉₂U), the experimental databases are normalized to their corresponding values of the ECPSSR model to deduce the semi-empirical cross sections. These databases rely on the different compilations available in the literature and on the other data extracted from papers published from 1953 till 2010. In the present paper, a fourth order polynomial was used to fit very well the existing normalized database of K-shell ionization cross sections by proton. These procedures generate a new set of parameters for the sake of the quick calculation of the semi-empirical cross sections. A comparison is made between the deduced results and those obtained by using the ECPSSR model where a remarkable discrepancy is observed at low-proton velocity regime especially for the lightest elements

[en] A large database containing about 5400 experimental K-shell ionization cross-sections by protons for elements from Be to U is collected from various sources and compilations available in the literature from 1953 to 1999. The data are divided into groups corresponding to their atomic numbers and fitted separately by analytical functions to deduce empirical K-shell ionization cross-sections. The deduced empirical K-shell ionization cross-sections are presented together with the reference ones obtained by Paul and Sacher for selected elements [H. Paul, J. Sacher, At. Data Nucl. Data Tables 42 (1989) 105]. The two sets of results are compared to the calculations within the ECPSSR theory and discussed.

[en] The crystalline structure, grain morphology, electrical and electrochemical properties of Sr_2-xLa_xFeMoO₆ (x = 0, 0.25, 0.5 and 1) double perovskite has been investigated by means of X-ray powder diffraction, scanning electron micrography, electrical and electrochemical measurements. It was found that the grain morphology, the resistivity and the electrochemical activity are strongly influenced by La doping. While the surface area as the determining factor in the oxygen reaction rate was excluded, the electrical resistivity was found to have a great effect on the electrochemical activity of the compounds.