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In this paper, an optimization method based on a new class of basis functions, namely generalized polynomials (GPs), is proposed for nonlinear variable-order time fractional diffusion-wave equation. Variable-order time fractional derivative is expressed in the Caputo sense. In the proposed method, solution of the problem under consideration is expanded in terms of GPs with unknown free coefficients and control parameters. In this way, some new operational matrices of the ordinary and fractional derivatives are derived for these basis functions. The residual function and its 2-norm are employed for converting the problem under study to an optimization one and then choosing the unknown free coefficients and control parameters optimally. As a useful result, the necessary conditions of optimality are derived as a system of nonlinear algebraic equations with unknown free coefficients and control parameters. The validity and effectiveness of the method are demonstrated by solving some numerical examples. The results demonstrate that the proposed method is a powerful algorithm with good accuracy for solving such kind of problems. 相似文献
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In this paper, we present a numerical method for solving two-dimensional Volterra-Fredholm integral equations of the second kind (2DV-FK2). Our method is based on approximating unknown function with Bernstein polynomials. We obtain an error bound for this method and employ the method on some numerical tests to show the efficiency of the method. 相似文献
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Sh. Dehghan Abkenar Z. Dahaghin H. Bagheri Sadeghi M. Hosseini M. Salavati-Niasari 《Journal of Analytical Chemistry》2011,66(6):612-617
In this study, a new and simple homogeneous liquid-liquid extraction (HLLE) method based on a pH-independent phase-separation process was developed using a ternary solvent system [water-tetrabutylammonium
ion (TBA
+)-chloroform] for the preconcentration of Zn2+ ions. A Schiff’s base ligand was used as the chelating agent prior to Zn2+ ions extraction. Flame atomic absorption spectrophotometry using acetylene-air flame was used for the quantification of analyte
after preconcentration. The phase separation occurred due to ion-pair formation of TBA and perchlorate ion. The sedimented
phase was then separated using a 100 μL micro-syringe and diluted to 1.0 mL with ethanol. The sample was introduced into the
flame by conventional aspiration. After the optimization of complexation and extraction conditions such as pH 9.0, [ligand]
= 1.0 × 10−5 M, [TBA+] = 2.0 × 10−2 M, 100.0 μL of [CHCl3] and [CLO4−] = 2.0 × 10−2 M, a preconcentration factor of 100 was achieved for only 10 mL of the sample. The relative standard deviation was 2.3% (n = 10). The limit of detection was sufficiently low and at ppb level. The proposed method was applied to the extraction and
determination of Zn2+ in natural water samples with satisfactory results. 相似文献
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Akbar Bagheri Mohammad Behbahani Mostafa M. Amini Omid Sadeghi Atieh Tootoonchi Zohreh Dahaghin 《Mikrochimica acta》2012,178(3-4):261-268
We present a study on the application of magnetic nanoparticles (MNPs) prepared from Fe3O4 and functionalized with pyridine as an adsorbent for the solid-phase extraction of trace quantities of Pd(II) ion. The pyridine group was immobilized on the surface of the MNPs by covalent bonding of isonicotinamide. The modified MNPs can be readily separated from an aqueous solution by applying an external magnetic field. Effects of pH, the amount of functionalized MNPs, extraction time, type and quantity of eluent, desorption time, break-through volume and interfering ions on the extraction efficiency were optimized. The amount of Pd(II) was then determined using FAAS. Under the optimized conditions, the detection limit and preconcentration factor are 0.15?μg?L-1 and 196, respectively, and the relative standard deviation (at 20?μgL?1; for n?=?10) is 3.7?%. The method had a linear analytical range from 1 to 80?μg?L-1 and was applied to determine Pd(II) in spiked tape water and soil. Figure
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Zohreh Dahaghin Hassan Zavvar Mousavi Ehsan Mirparizi Parand Haghighat 《Chemical Papers》2018,72(6):1451-1459
In this work for the first time, Fe3O4@SiO2 core–shell nanoparticles functionalized with isatin groups as a magnetic nanosorbent was applied for the simultaneous extraction of trace amounts of cadmium(II), nickel(II), lead(II), and zinc(II). The characterization of this nanosorbent was studied using Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectrometry, X-ray diffraction, vibrating sample magnetometer and thermogravimetric analysis. The effect of several factors such as pH, amount of sorbent, extraction time, type and volume of the eluent, sample volume, sorption capacity, and potentially interfering ions was investigated. In the selected conditions, it was observed that the limits of detection were 0.11 ng mL?1 for Cd(II), 0.28 ng mL?1 for Ni(II), 0.47 ng mL?1 for Pb(II), and 0.21 ng mL?1 for Zn(II), and the maximum sorption capacity of this suggested magnetic nanosorbent was 120, 112, 100, and 100 mg g?1 for Cd(II), Ni(II), Pb(II), and Zn(II), respectively. Also, the precision of the method (RSD%) for ten replicate measurements was found 2.5, 2.5, 2.8, and 3.1%, for Cd(II), Ni(II), Pb(II), and Zn(II) ions, respectively. Finally, the suggested procedure was applied for determination of cadmium(II), nickel(II), lead(II), and zinc(II) at trace levels in different water and agricultural products with satisfactory results. 相似文献
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Dahaghin Zohreh Mousavi Hassan Zavvar Sajjadi Maryam 《Journal of Sol-Gel Science and Technology》2018,86(1):217-225
Journal of Sol-Gel Science and Technology - In this work for the first time, magnetic nanoporous SBA-15 functionalized with isatin groups as a magnetic nanosorbent was applied for the simultaneous... 相似文献
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