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A numerical method for solving the controlled Duffing oscillator is presented. The method is based upon hybrid functions approximation. The properties of hybrid functions which consists of block-pulse functions plus Legendre polynomials are given. The method is based upon expanding various time functions in the system as their truncated hybrid functions. The operational matrix of product is introduced. This matrix together with the operational matrix of integration are utilized to reduce the solution of controlled Duffing oscillator to the solution of algebraic equations. Illustrative examples are included to demonstrate the validity and applicability of the technique. 相似文献
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Gholami Mohammad Reza Akbari Omid Ali Marzban Ali Toghraie Davood Shabani Gholamreza Ahmadi Sheikh Zarringhalam Majid 《Journal of Thermal Analysis and Calorimetry》2018,134(3):1611-1628
Journal of Thermal Analysis and Calorimetry - In this research, the laminar and forced flow and heat transfer of oil/multi-walled carbon nanotubes nanofluid in a microchannel have been numerically... 相似文献
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Alireza Aslani Mohammadreza Arefi Khalil Beyki-Shuraki Aziz Babapoor 《Journal of Saudi Chemical Society》2013,17(4):403-407
Lead iodide, bromide and chloride nanoparticles (NP-PbX2, X = I, Br and Cl) with various morphologies were successfully prepared through a simple hydrothermal method without any additives or stabilizers. By treating the PbX2 in EtOH/CH2Cl2 solution at 170 °C for 12 h, the corresponding PbX2 nanoparticles were synthesized. The average sizes of PbX2 nanoparticles were between 30 and 80 nm. The structure, morphology, surface and size of PbX2 nanoparticles were determined by X-ray diffraction powder, Scanning Electron Microscopy, solid state Photo Luminescent, BET surface area and solid state UV. 相似文献
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H. R. Marzban S. M. Hoseini M. Razzaghi 《Mathematical Methods in the Applied Sciences》2009,32(2):127-134
A numerical method for solving Volterra's population model for population growth of a species in a closed system is proposed. Volterra's model is a nonlinear integro‐differential equation where the integral term represents the effects of toxin. The approach is based on hybrid function approximations. The properties of hybrid functions that consist of block‐pulse and Lagrange‐interpolating polynomials are presented. The associated operational matrices of integration and product are then utilized to reduce the solution of Volterra's model to the solution of a system of algebraic equations. The method is easy to implement and computationally very attractive. Applications are demonstrated through an illustrative example. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Fariba Fathi Laleh Majari‐Kasmaee Ahmad Mani‐Varnosfaderani Anahita Kyani Mohammad Rostami‐Nejad Kaveh Sohrabzadeh Nosratollah Naderi Mohammad Reza Zali Mostafa Rezaei‐Tavirani Mohsen Tafazzoli Afsaneh Arefi‐Oskouie 《Magnetic resonance in chemistry : MRC》2014,52(7):370-376
The present study was designed to search for metabolic biomarkers and their correlation with serum zinc in Crohn's disease patients. Crohn's disease (CD) is a form of inflammatory bowel disease that may affect any part of the gastrointestinal tract and can be difficult to diagnose using the clinical tests. Thus, introduction of a novel diagnostic method would be a major step towards CD treatment. Proton nuclear magnetic resonance spectroscopy (1H NMR) was employed for metabolic profiling to find out which metabolites in the serum have meaningful significance in the diagnosis of CD. CD and healthy subjects were correctly classified using random forest methodology. The classification model for the external test set showed a 94% correct classification of CD and healthy subjects. The present study suggests Valine and Isoleucine as differentiating metabolites for CD diagnosis. These metabolites can be used for screening of risky samples at the early stages of CD diagnoses. Moreover, a robust random forest regression model with good prediction outcomes was developed for correlating serum zinc level and metabolite concentrations. The regression model showed the correlation (R2) and root mean square error values of 0.83 and 6.44, respectively. This model suggests valuable clues for understanding the mechanism of zinc deficiency in CD patients. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Dispersive liquid—liquid microextraction coupled with high-performance liquid chromatography—diode-array detection was applied
for the extraction and determination of 11 priority pollutant phenols in wastewater samples. The analytes were extracted from
a 5-mL sample solution using a mixture of carbon disulfide as the extraction solvent and acetone as the dispersive solvent.
After extraction, solvent exchange was carried out by evaporating the solvent and then reconstituting the residue in a mixture
of methanol–water (30:70). The influences of different experimental dispersive liquid—liquid microextraction parameters such
as extraction solvent type, dispersive solvent type, extraction and dispersive solvent volume, salt addition, and pH were
studied. Under optimal conditions, namely pH 2, 165-μL extraction solvent volume, 2.50-mL dispersive solvent volume, and no
salt addition, enrichment factors and limits of detection ranged over 30–373 and 0.01–1.3 μg/L, respectively. The relative
standard deviation for spiked wastewater samples at 10 μg/L of each phenol ranged between 4.3 and 19.3% (n = 5). The relative recovery for wastewater samples at a spiked level of 10 μg/L varied from 65.5 to 108.3%. 相似文献
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Hassan Mallaekeh Alireza Shams Mohammad Shaker Ehsan Bahramzadeh Donya Arefi 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2014,88(12):2081-2086
In this paper the complexation reaction of the 5,5′-(2E,2′E)-2,2′-(ethane-1,2-diylidene)bis(hydrazine-1-yl-2-ylidene)bis(4-amino-4H-1,2,4-triazole-3-thiol) ligand (HYT) with Cd2+ education was studied in some binary mixtures of methanol (MeOH), n-propanol (PrOH) and dimethyl-formamide (DMF) at different temperatures using the conductometry and spectrophotometry. The stability constants of the complex was determined using a GENPLOT computer program. The conductance data and absorbance-mole ratio plots show that in all solvent systems, the stoichiometry of the complex formed between (HYT) and Cd2+ cation is 1: 1. The obtained results show that the stability of (HYT)-Cd complex is sensitive to the mixed solvents composition. The values of thermodynamic parameters (ΔG °, ΔH °, and ΔS °) for formation of (HYT)-Cd complex were obtained from temperature dependence of the stability constant using the van’t Hoff plots. The results show that in most cases, the complex are enthalpy destabilized but entropy stabilized and the complex formation is affected by pH, time, temperature and the nature of the solvent. 相似文献