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Further Results on Chebyshev and Steffensen Inequalities
Dahmani, Zoubir,Bounoua, Mohamed Doubbi Department of Mathematics 2018 Kyungpook mathematical journal Vol.58 No.1
By making use of the Riemann-Liouville fractional integrals, we establish further results on Chebyshev inequality. Other Steffensen integral results of the weighted Chebyshev functional are also proved. Some classical results of the paper:[ Steffensen's generalization of Chebyshev inequality. J. Math. Inequal., 9(1), (2015).] can be deduced as some special cases.
F. Dahmani,C. H. Sohn 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.5
Unsteady 2D laminar flow simulations were performed on tandem oscillating hydrofoils to study the influence of the downstream spatial location on the power extraction efficiency of a tandem/parallel combined configuration. A sinusoidal plunging/pitching motion of NACA 0015 profile was used. Inspired by insect inter-wing spacing, different configurations of the downstream foil (y)-position were first studied at a fixed (L/c) horizontal inter-foil spacing and reduced frequencies within the range of 0.02 to 0.32. It was found that the energy extraction efficiency improved by around 23 % as compared to the conventional tandem configuration by changing the vertical inter-foil spacing. An interesting finding is that, at specified frequencies and inter-foil spacing, the power efficiency extracted from the downstream foil, associated with the new configuration, exceeds the upstream foil efficiency. The horizontal inter-foil spacing was then investigated for an optimal (y)-position of the downstream foil, and the results show that the optimal horizontal spacing was reduced compared to the conventional tandem configuration, resulting in a gain in space and about 15 % of increment in the power extraction efficiency. Therefore, a total of 38 % of power efficiency enhancement was obtained at * f = 0.24 by using the new configuration in which the horizontal inter-foil spacing was reduced five times compared to the conventional configuration. An appropriate inter-foil spacing/frequency synchronization resulted in a favorable foil-vortex interaction that improves the power extraction from the oscillating foil system. The frequency and the inter-foil spacing were found to be critical factors that determine whether the interaction is favorable or unfavorable.
Iqbal Jebril,Yazid GOUARI,Mahdi RAKAH,Zoubir Dahmani 경남대학교 수학교육과 2023 Nonlinear Functional Analysis and Applications Vol.28 No.4
In this paper, we work two different problems. First, we investigate a new class of fractional differential equations involving Caputo sequential derivative with some $(e_1,e_2, \theta )-$periodic conditions. The existence and uniqueness of solutions are proven. The stability of solutions is also discussed. The second part includes studying traveling wave solutions of a conformable fractional Korteweg-de Vries-Burger (KdV Burger) equation through the Tanh method. Graphs of some of the waves are plotted and discussed, and a conclusion follows.
Prerna Chaturvedi,Amarsingh Bhabu Kanagaraj,Maryam Sultan Al Nahyan,Hamda Al Shibli,Hamda Al Shibli,Hamed Fadaq,Sultan Al Dahmani,Daniel S. Choi 한국물리학회 2019 Current Applied Physics Vol.19 No.11
The spinel lithium titanate oxide (Li4Ti5O12, LTO) has been extensively studied as one of the most promising alternatives to carbon materials in energy conversion and storage devices, due to its high structural and thermal stability, rate capability, and excellent cycling stability. In this study, Li4Ti5O12/multi-walled carbon nanotubes (LTO-MWCNTs) free-standing and flexible composite electrodes/buckypapers were prepared via tape casting technique and well compared with commercially available LTO. The structural, morphological, electrical and electrochemical properties of LTO-MWCNTs buckypaper as well as LTO were studied. The electrical conductivity of LTO-based buckypaper was found to be very high i. e, 4.4×102 Scm−1 at room temperature. Further, the buckypaper prepared by synthesized LTO showed higher specific capacity (166 mAhg−1) compared to commercially available LTO (137 mAhg−1) at 0.2 C rate. The enhanced electrochemical performance of as-synthesized LTO-based buckypaper is mainly attributed to the higher electronic conductivity and homogeneous distribution of particles with its small size which facilitates large amount of active sites for lithium insertion and also short diffusion paths.