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51.
Khaled I. Doudin Jon Songstad Karl W. Trnroos 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(4):439-440
In contrast to Se[CH2C(O)OH]2versus S[CH2C(O)OH]2, the title compound, Se[CH2CH2C(O)OH]2 or C6H10O4Se, is structurally quite similar to its sulfur analogue. The molecule has twofold symmetry. The C—Se—C bond angle is 96.48 (8)° and the Se—C bond lengths are 1.9610 (14) Å. The shortest Se?O intermolecular distance is 3.5410 (11) Å. The O?O distances in the carboxylic acid dimers are 2.684 (2) Å. The temperature dependence of the IR spectrum suggests tautomerism in the solid state. 相似文献
52.
Khaled Khodary Esmaeil 《Heat and Mass Transfer》2013,49(1):41-54
Laminar natural convective heat transfer of nanofluids inside an enclosure is numerically investigated considering the thermal dispersion effect of the nanoparticles. Feasibility of applying nanofluids instead of pure liquids in natural convective, which is a discrepancy issue between the previous numerical and experimental works, is examined. Results confirm the previous experimental results of general deterioration in heat transfer rate. Discussions, justifications and correlations for average Nusselt number are presented. 相似文献
53.
54.
This paper presents an alternative semi-blind watermarking algorithm in gray scale images. The new watermarking system changes
the coefficients of discrete cosine transform in homogeneous manner. This algorithm is based on the modification of the base
using the concept of the norm or the distance. Experimental results introduced at the end of this paper, demonstrates the
robustness of the proposed strategy against different attacks. 相似文献
55.
D. G. Steyn Ch. O. Wilson L. W. Rising F. Halstrom T. S. Gussewa L. Vignoli A. Ben Khaled C. M. Jephcott F. M. R. Bulmer und O. Schmidt 《Fresenius' Journal of Analytical Chemistry》1940,120(1-2):77-80
Ohne Zusammenfassung 相似文献
56.
Eqab M. Rabei Khaled I. Nawafleh Sami I. Muslih 《Journal of Mathematical Analysis and Applications》2007,327(2):891-897
Recently the traditional calculus of variations has been extended to be applicable for systems containing fractional derivatives. In this paper the passage from the Lagrangian containing fractional derivatives to the Hamiltonian is achieved. The Hamilton's equations of motion are obtained in a similar manner to the usual mechanics. In addition, the classical fields with fractional derivatives are investigated using Hamiltonian formalism. Two discrete problems and one continuous are considered to demonstrate the application of the formalism, the results are obtained to be in exact agreement with Agrawal's formalism. 相似文献
57.
A Proactive Crew Recovery Decision Support Tool for Commercial Airlines During Irregular Operations 总被引:2,自引:0,他引:2
Ahmed Abdelghany Goutham Ekollu Ram Narasimhan Khaled Abdelghany 《Annals of Operations Research》2004,127(1-4):309-331
In this paper, a decision support tool that automates crew recovery during irregular operations for large-scale commercial airlines is presented. The tool is designed for airlines that adopt the hub-spoke network stru cture. The advance of this tool over the existing ones is that it recovers projected crew problems that arise due to current system disruptions. In other words, it proactively recovers crew problems ahead of time before their occurrence. In addition, it gives a wide flexibility to react to different operation scenarios. Also, it solves for the most efficient crew recovery plan with the least deviation from the originally planned schedule. The tool adopts a rolling approach in which a sequence of optimization assignment problems is solved such that it recovers flights in chronological order of their departure times. In each assignment problem, the objective is to recover as many flights as possible while minimizing total system cost resulting from resource reassignments and flight delays. The output of this tool is in the form of new crew trippairs that cover flights in the considered horizon. A test case is presented to illustrate the model capabilities to solve a real-life problem for one of the major commercial airlines in the U.S. 相似文献
58.
Hysteresis phenomena in multi-phase flow in porous media has been recognized by many researchers and widely believed to have significant effects on the flow. In an attempt to account for these effects, a theoretical model for history-dependent relative permeabilities is considered. This model is incorporated into 1-D two-phase nondiffusive flow system and the corresponding flow is predicted. Flow history is observed to have a notable impact on the saturation profile and fluids breakthrough. 相似文献
59.
Saoussen Hammami Ridha El Mokni Khaled Faidi Danilo Falconieri Alessandra Piras Silvia Procedda 《Natural product research》2015,29(24):2336-2340
The objectives of this study were to chemically characterise and evaluate the antioxidant potential of the essential oil from Teucrium flavum L. subsp. flavum growing spontaneously in Tunisia. The volatile oil was extracted by hydrodistillation of the aerial parts in a Clevenger type apparatus. Forty constituents were identified via GC and GC-MS analysis. β-caryophyllene (32.5%) and α-humulene (17.8%) were the most abundant components. The evaluation of free radical scavenging activity using stable DPPH free radical showed that the volatile oil exhibits a moderate antioxidant activity and reduces DPPH to 50% at EC50 value of 1230 μg mL? 1. 相似文献
60.
Said A. S. Ghozlan Fathy M. Abdelrazek Mona H. Mohammed Khaled E. Azmy 《Journal of heterocyclic chemistry》2014,51(4):1179-1184
The newly synthesized ethyl 3‐amino‐5‐phenylpyrazole‐4‐carboxylate 1 was diazotized and coupled with β‐naphthol, active methylene reagents 6 , 9 , 12 , 15 , and the active methine 19 to afford the pyrazolo[5,1‐c]triazines 5 , 8 , 11 , 14 , 17 , 18 , and the pyrazolo[5,1‐ c ]‐1,2,4‐triazoles 21 , 22 , and 23 , respectively. Structures are elucidated and mechanisms are discussed. 相似文献