Free boundary problems with nonlinear diffusion occur in various applications, such as solidification over a mould with dissimilar nonlinear thermal properties and saturated or unsaturated absorption in the soil beneath a pond. In this article, we consider a novel inverse problem where a free boundary is determined from the mass/energy specification in a well-posed one-dimensional nonlinear diffusion problem, and a stability estimate is established. The problem is recast as a nonlinear least-squares minimisation problem, which is solved numerically using the
The spectral characteristics and the nonlinear optical properties of the mixed donor (C-480) acceptor (Rh-6G) have been determined. The spectral characteristics are studied by recording their absorption and fluorescence spectra. The nonlinear optical properties were measured by z-scan technique, using Q-switched Nd: YAG laser with 1064 nm wavelength. The results showed that the optimum concentration of acceptor is responsible for increasing the absorption and the emission bandwidth of donor to full range and to 242 nm respectively by the energy transfer process, also the efficiency of the process was increased by increasing the donor and acceptor concentration. The obtained nonlinear properties results of the mixture C-480/ Rh-6G showed
... Show MoreThis research is devoted to investigate the behavior and performance of reinforced concrete beams strengthened with externally bonded Carbon Fiber Reinforced Polymer (CFRP) laminates under the effect of torsion. In this study a theoretical analysis has been conducted using finite element code ANSYS. Six previously tested beams are used to investigate reinforced concrete beams behavior
under torsion, two of them are solid and the rest are box-section beams. Also, two beams are without CFRP reinforcement, which are used as control beams for the strengthened one, and the other four beams are strengthened with CFRP laminates with different number of layers and spacing. Numerical investigation is conducted on these beams, and comparisons b
The aim of this paper is to present a semi - analytic technique for solving singular initial value problems of ordinary differential equations with a singularity of different kinds to construct polynomial solution using two point osculatory interpolation. The efficiency and accuracy of suggested method is assessed by comparisons with exact and other approximate solutions for a wide classes of non–homogeneous, non–linear singular initial value problems. A new, efficient estimate of the global error is used for adaptive mesh selection. Also, analyze some of the numerical aspects
... Show MoreIn this paper, the general framework for calculating the stability of equilibria, Hopf bifurcation of a delayed prey-predator system with an SI type of disease in the prey population, is investigated. The impact of the incubation period delay on disease transmission utilizing a nonlinear incidence rate was taken into account. For the purpose of explaining the predation process, a modified Holling type II functional response was used. First, the existence, uniform boundedness, and positivity of the solutions of the considered model system, along with the behavior of equilibria and the existence of Hopf bifurcation, are studied. The critical values of the delay parameter for which stability switches and the nature of the Hopf bifurcat
... Show MoreIn this research, the study effect of additive titanium dioxide powder (TiO2) as a lone composite ( Ep+TiO2) and a mixture of (TiO2) and silicon oxide (SiO2), ( Ep+ TiO2+SiO2)as a hybrid composite on the mechanical and physical properties for epoxy coating. Thescompsiteswere prepared by (Hand Lay- the molding) method. The samples were tested for compressive strength, surface hardness, modulus of elasticity, thermal conductivity and diffusion coefficient, from the results obtained showed improvement in mechanical properties after adding ceramic powders, as the alone composite (EP+ TiO2) had the highest compressive strength ( 53.738 ) ᴍPa, the hybrid composite ( EP+TiO2 +SiO2 ) had the
... Show MoreThis current study was built on creating four electrodes based on molecularly imprinted polymers (MIPs). As the template using Cefalexin (CFX), 1-vinyl imidazole (VIZ) and vinyl acetate (VA) as monomer, and N, N-methylene bis acrylamide (MBAA) as cross-linkers and benzoyl peroxide as the initiator, two MIPs were prepared. The same composition was used in non-impressed polymers (NIPs) preparation, but without the template (Cefalexin). For the membranes preparation, numerous plasticizers, such as tri-oly phosphate (TOP) and di-octyl phthalate (DOP), were used in the PVC matrix, slop, detection limit, lifetime, and linearity range of CFX-MIPs electrodes are characteristics &nb
... Show MoreThe trace elements in the medical herbs play an important role in the treatment of diseases. Well selected herbs samples of Iraqi herbs and collected from local markets. In this study, the concentrations of nine elements Na,K, Zn, Fe ,Co ,Cu ,Ni , Pb and Cd were determined in fourteen kinds herbs common belonging to Matricaria Chamomile Cinnamon,Pimpinella Anisum L., Zea Maize , Anethum Graveolens L., Jeft, Teucrium Polium L., Cagsia Italica,Echium Talicum L.,Ocimum Basilcum L., Galeopsis Sejetum,Nigella Sative L., Cyperus Rotundus L.,Lupinus Jaimehintoniana.The herbs samples were analysed by flameless except Na,K, in flame atomic absorption spectrophotometer in different medical herbs.The results indicated that the Na and K
... Show MoreVerapamil Hydrochloride (VH) has been determined spectrophotometrically by using Methyl Orange (MO). In our previous researches MO was used for determination of Mexiletine Hydrochloride [1]. The method was based on complexation between (MO and VH). After shaking and diluting the complex solution with D.W, the pH was adjusted with NaOH and HCl to pH 4. The colored complex formed between VH and the reagents were transferred into separating funnels and extracted using 4.5 ml CH2Cl2 and were shaken for (4 minutes). The extracted organic layer was used for the preparation of the calibration curves for spectrophotometric measurements of VH at 437nm. The blanks were carried out in exactly the same way throughout the whol
... Show MoreVitamins are a type of essential and important nutrient in the human body. It also plays an essential role in the health and protection of the human body. They share physiological functions with many chemicals, and their deficiency or increase endangers human health. Therefore, it is required to evolve and use modern methods to estimate the concentration of vitamins, even if their concentration is very low, and these include the vitamin E group tocopherols, tocotrienols, isomers, esters, and derivatives. They disagree not in their ability as anti-cancer agents but rather in their physiological as well as chemical relations, unlike vitamin A and vitamin D. The richest source of vitamin E is vegetable oil. Vitamin E, classified as a vitami
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