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321.
Ekrem Aydiner Yusuf Yüksel Hamza Polat 《Journal of magnetism and magnetic materials》2009,321(19):3193-3197
In this study, dependence on site dilution of critical and compensation temperatures of a two-dimensional mixed spin-1/2 and spin-1 system has been investigated with Monte Carlo simulation. The dependence of the thermal and magnetic behaviors on dilution of mixed spin system has been discussed. We have shown that the critical and compensation temperatures of diluted mixed spin system linearly decrease with increasing number of diluted sites. 相似文献
322.
We unify, under a one parameter family, the most common estimators of the mean and the variance of the offspring distribution for a supercritical one-type branching process. We give the rate for the almost-sure convergence, and the asymptotic normality for each one of these estimators. We select, within this family, the “best” estimators for the mean, the variance, and the pair (mean, variance). The asymptotic independence for the standardized estimation errors is also established. To cite this article: K. Hamza, F. Maâouia, C. R. Acad. Sci. Paris, Ser. I 347 (2009). 相似文献
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A. Z. Nowakowski R. B. Dennis T. Scragg F. H. Hamza S. D. Smith 《Optics & Laser Technology》1976,8(3):133-136
Double beam optical techniques which allow direct spectroscopic measurements using both pulsed and cw tunable spin-flip Raman lasers have been developed. The systems provide a high resolution spectrometer (spectral linewidths 0.03 cm-1 pulsed and 0.003 cm-1 cw) in the range 5.3–6μm. Line frequency measurements are accurate to 0.01 cm-1 and intensity measurements to a few percent. Results of molecular spectroscopy provide a comparison of the relative performance of each system. 相似文献
326.
Mohamed Hilmy Elnagdi Mohamed Ali Elsayed Khalifa Mohamed Kamal Ahmed Ibraheim Mohamed Riffat Hamza Elmoghayar 《Journal of heterocyclic chemistry》1981,18(5):877-879
The reaction of mercaptoacetic acid with nitriles was investigated. Whereas 4-hydroxythiazole derivative could be obtained from the reaction of benzoylacetonitrile and of ethyl cyanoacetate with mercaptoacetic acid, a bithiazole derivative was obtained on treatment of benzonitrile with the same reagent. The behaviour of the synthesised thiazole derivatives towards aromatic aldehydes and hydrazines is reported. 相似文献
327.
Constrained optimization is an important research topic that assists in quality planning and decision making. To solve such problems, one of the important aspects is to improve upon any constraint violation, and thus bring infeasible individuals to the feasible region. To achieve this goal, different constraint consensus methods have been introduced, but no single method performs well for all types of problems. Hence, in this research, for solving constrained optimization problems, we introduce different variants of the Differential Evolution algorithm, with multiple constraint consensus methods. The proposed algorithms are tested and analyzed by solving a set of well-known bench mark problems. For further improvements, a local search is applied to the best variant. We have compared our algorithms among themselves, as well as with other state of the art algorithms. Those comparisons show similar, if not better performance, while also using significantly lower computational time. 相似文献
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329.
Yusuf
zcan Semra de Mehmet Karakus Hamza Ylmaz 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(7):m388-m389
In the the title compound, [Ni(C21H28O2PS2)2], the Ni atom resides on an inversion centre and is coordinated in a square‐planar array by four S atoms, with Ni—S and P—S bond lengths of 2.2336 (12)/2.2351 (13) and 1.9910 (16)/2.0010 (17) Å, respectively. The two O‐2,4‐di‐tert‐butylphenyl and two 4‐methoxyphenyl moieties adopt trans configurations about the central Ni atom. 相似文献
330.
Pápai I Hamza A Pihko PM Wierenga RK 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(10):2859-2866
Protein crystallographic analysis of the active sites of enolizing enzymes and structural analysis of hydrogen-bonded carbonyl compounds in small molecule crystal structures, complemented by quantum chemical calculations on related model enolization reactions, suggest a new stereoelectronic model that accounts for the observed out-of-plane orientation of hydrogen-bond donors (HBDs) in the oxyanion holes of enolizing enzymes. The computational results reveal that the lone-pair directionality of HBDs characteristic for hydrogen-bonded carbonyls is reduced upon enolization, and the enolate displays almost no directional preference for hydrogen bonding. Positioning the HBDs perpendicular to the carbonyl plane induces strain in the catalyst-substrate complex, which is released upon enolization, resulting in more favorable kinetics and thermodynamics than the in-plane arrangement of HBDs. 相似文献