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31.
In this paper, the size-dependent free vibration of magneto-electro-elastic (MEE) nanobeams in thermal environment is investigated. Size effects are taken into account using the modified couple stress theory, which is capable of accounting for higher-order electromechanical coupling, and the equations are developed on the basis of Euler–Bernoulli beam model and using von Karman nonlinear strain. The vibration of hinged–hinged nanobeams is investigated by way of example. Effects of various parameters such as temperature, thickness, and length on natural frequencies are demonstrated, and it is indicated that increased length and decreased thickness lead to decreased nanobeam natural frequencies. 相似文献
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In this paper,a new simple structure of indexguiding photonic crystal fiber (PCF) is designed and presented.In this PCF,dispersion,confinement loss,and effective mode area characteristics are investiga... 相似文献
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The cysteamine hydrochloride as a practical precursor of 2-(nitromethylene)thiazolidine in the one-pot synthesis of thiazoloquinoline derivatives from aromatic aldehydes and dimedone is described. This protocol involved Michael reaction, imine–enamine tautomerization, and cyclization sequence. Simple operation under mild conditions, easy accessibility of reactants, short reaction times, simple workup procedure, high atom economy, and the use of ethanol/water as a green medium make this approach attractive for the synthesis of variety of such derivatives. 相似文献
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We present a new strategy for flexible attachment of peptide amphiphiles on functionalized silicon surfaces. This method involves the production of an alkylated surface on which a lipidated peptide can then be attached through hydrophobic interaction. We applied this to two derivatives of amphiphilic peptide molecules with the same amino acid sequence (A-A-A-A-G-G-G-E-R-G-D) but different in alkyl chain lengths (palmitic acid, undecanoic acid). The basis of this work was to develop substrates which are more biocompatible and bioactive. The ultra-thin peptide amphiphile films were characterized using electrical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (ATR-FTIR) spectroscopy. The results demonstrated that the length of the alkyl chain in the peptide amphiphile affects the packing and coverage of the peptides on the silicon surface. 相似文献
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Fahimeh Tanhaei Nasim Nahavandi 《The International Journal of Advanced Manufacturing Technology》2013,64(5-8):1161-1167
The theory of constraints is an approach to production planning and control that emphasizes on the constraints in the system to increase throughput. One application in the theory of constraints is product mix decision. The objective of this paper is to present an algorithm to determine the product mix in a two-constraint resources environment. The theory of constraints solution could not reach optimum solution and has the risk of being infeasible when multiple constraint resources exist. The proposed algorithm is suitable for improving solutions obtained from theory of constraints and could provide throughput in product mix problems. Some alternatives are compared in this paper: the standard theory of constraints, integer linear programming, tabu search, hybrid tabu simulated annealing, and proposed algorithm solution. The numerical result shows the advantages of the proposed algorithm. 相似文献
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Saleh Mobayen Sifeu Takougang Kingni Viet-Thanh Pham Fahimeh Nazarimehr 《International journal of systems science》2018,49(3):617-630
This paper investigates a three-dimensional autonomous chaotic flow without linear terms. Dynamical behaviour of the proposed system is investigated through eigenvalue structures, phase portraits, bifurcation diagram, Lyapunov exponents and basin of attraction. For a suitable choice of the parameters, the proposed system can exhibit anti-monotonicity, periodic oscillations and double-scroll chaotic attractor. Basin of attraction of the proposed system shows that the chaotic attractor is self-excited. Furthermore, feasibility of double-scroll chaotic attractor in the real word is investigated by using the OrCAD-PSpice software via an electronic implementation of the proposed system. A good qualitative agreement is illustrated between the numerical simulations and the OrCAD-PSpice results. Finally, a finite-time control method based on dynamic sliding surface for the synchronisation of master and slave chaotic systems in the presence of external disturbances is performed. Using the suggested control technique, the superior master–slave synchronisation is attained. Illustrative simulation results on the studied chaotic system are presented to indicate the effectiveness of the suggested scheme. 相似文献
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Fahimeh Emadi Ali Nemati Manuel Hinterstein Esmaeil Adabifiroozjaei 《Ceramics International》2019,45(5):5503-5510
In the present work the effect of simultaneous doping of carbon and nickel on the microstructural, optical, and electrical properties of barium strontium titanate (BST) is investigated. Thin films of BST were prepared by the sol-gel method in six different compositions ((Ba0.6Sr0.4)(NixCyTi1-x-y)O3): x?=?y?=?0.00 (BST), x?=?0.04?y?=?0.00 (BST4N), x?=?0.04?y?=?0.01 (BST4N-1C), x?=?0.04?y?=?0.02 (BST4N-2C), x?=?0.04?y?=?0.03 (BST4N-3C), and x?=?y?=?0.04 (BST4N-4C). Structural features and chemical bonds of the films were studied by TGA/DSC, XRD, FT-IR, and FE-SEM. The electrical and optical properties of the films were analysed by impedance spectroscopy and UV–VIS spectroscopy. The results show that addition of Ni and C leads to Ti4+-Ni2+ and Ti4+-C4+ replacements, respectively. These replacements lead to a gradual increase in the band gap energy; from 3.15?eV for BST to 3.44, 3.5, 3.66, 3.73 and 3.76?eV for BST4N, BST4N-1C, BST4N-2C, BST4N-3C, and BST4N-4C, respectively. In contrast, the dielectric loss decreases significantly from 0.055 for BST to 0.031, 0.033, 0.03, 0.022 and 0.01 for BST4N, BST4N-1C, BST4N-2C, BST4N-3C, and BST4N-4C, respectively. At the same time, the quality factor Qf (1/ tanδ) increases substantially from 15 for BST to 32, 30, 33, 44 and 87 for BST4N, BST4N-1C, BST4N-2C, BST4N-3C, and BST4N-4C, respectively. In contrast, the frequency dependence of the capacity decreases in comparison to un-doped BST. Among all films, the BST4N-4C had the highest figure of merit (FOM), least dielectric loss, and very low frequency-dependence, making it the best candidate for tuneable device applications. 相似文献
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Fahimeh Sadat Mohammadi Daryush Arabian 《Journal of the American Oil Chemists' Society》2023,100(1):45-56
The aim of this study was to determine and optimize culture media for Chlorella vulgaris microalgae under mixotrophic conditions using waste molasses as a cheap carbon source containing both organic carbons and other nutrients. In the current study, at first the growth and lipid productivity of C. vulgaris were assessed in different culture media and the best media was selected for mixotrophic growth conditions. Significant medium ingredients were screened through Plackett–Burman design. Then ingredients with positive effect were considered as a mixture component and their combinations were evaluated on lipid productivity using mixture design. According to results, Zarrouk medium was considered as the base medium with the highest biomass and lipid productivity of 72 and 7.1 mg L−1 d−1, respectively. Based on the Plackett–Burman design, out of 11 factors, molasses, NaNO3 and K2HPO4 demonstrated key roles in biomass and lipid productivity in mixotrophic conditions. Consequently, the selected three factors were investigated by mixture design. The results showed that high concentration of molasses causes decrease in biomass and lipid productivity due to high turbidity and a blend consisting of approximately 9.5 g L−1 molasses, 5 g L−1 NaNO3 and 0.15 g L−1 K2HPO4 was found as the optimum mixture with obtained lipid productivity of 115 mg L−1 d−1. In conclusion, waste molasses can be used as a promising feedstock for cost effective cultivation of C. vulgaris. 相似文献