Journal of the Association of Arab Universities for Basic and Applied Sciences最新文献

The modified regularized long wave (MRLW) equation is numerically solved using Fourier spectral collection method. The MRLW equation is discretized in space variable by the Fourier spectral method and Leap-Frog method for time dependence. To validate the efficiency, accuracy and simplicity of the used method, four cases study are solved. The single soliton wave motion, interaction of two solitary waves, interaction of three solitary waves and a Maxwellian initial condition pulse are studied. The $L_2$ and $L_{\infty }$ error norms are computed for the motion of single solitary waves. To determine the conservation properties of the MRLW equation three invariants of motion are evaluated for all test problems.

This paper is devoted to the study of ninth order boundary value problems that emerge in the mathematical modeling of AFTI-F16 fighter. An augmented longitudinal and lateral dynamics of the AFTI-F16 fighter is described by ninth order differential equations, containing unknown parameters which can be determined using automated system identification algorithms. The solution of the boundary value problem is obtained in terms of a convergent series using homotopy analysis method (HAM). The method is effectively applied on numerical examples and the results are compared with those given in the literature, revealing that the presented method gives better approximations to the exact solution.

In this work, we are concerned with the investigation of the qualitative behaviors of certain systems of non-linear differential equations of second order. We make a comparison between applications of the integral test and Lyapunov’s function approach on some recent stability and boundedness results in the literature. An example is furnished to illustrate the hypotheses and main results in this paper.

The principal object of this paper is to present a natural further step toward the mathematical properties and presentations concerning the two variable Laguerre matrix polynomials defined in (Bin-Saad, Maged G., Antar, A. Al-Sayaad, 2015. Study of two variable Laguerre polynomials via symbolic operational images. Asian J. of math. and comput. research, 2(1), 42–50). Series expansions, integral transforms and bilinear and bilateral generating matrix functions for these polynomials are established. Some particular cases and consequences of our main results are also considered.

In this work, a low cost preparation scheme of Na-A zeolite from low cost materials was described. Aluminum scrubs were used to prepare sodium aluminate. Commercial sodium silicate and sodium aluminate were then used in the synthesis of zeolite through hydrothermal method under mild conditions. X-ray fluorescence (XRF), X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques were employed to confirm the synthesis of pure Na-A zeolite phase. The specific surface area (BET) of the prepared zeolite has also been measured. Results indicated that zeolite has relatively high surface area (=374 m²/g). The performance of the prepared zeolite in the removal of Cd²⁺, a highly toxic heavy metal, from water was investigated. The removal of Cd²⁺ from water which occurred through precipitation and ion exchange mechanisms was seen to be more efficient comparing to the previous studies. The maximum sorption capacity of Cd²⁺ was found to be 54.05 meq/100 g according to the Langmuir isotherm model. However, the sorption capacity was found to be 84.09 meq/100 g after 4 repetitions which is attributed to the ease of reaching the Cd²⁺ ions to the inner pores of zeolite upon using slightly dilute Cd²⁺ solutions in each repetition.

In this paper, an analytical approximate technique based on modified harmonic balance method is presented to study about the dynamics of a finite extensibility nonlinear oscillator described by Febbo (2011) and Beléndez et al. (2012). Generally, a second-order approximation is only considered in this paper. In the proposed method, the approximate period of oscillations and the corresponding periodic solutions are determined, which are valid for both range of amplitudes 0 < A ≤ 0.9 and 0.9 < A < 1 of oscillation. The approximate periods obtained in this paper are compared with numerical result (considered to be exact) and other existing results. Firstly, the results are obtained for the amplitude 0 < A ≤ 0.9 and show that the present method gives high accuracy than other existing results. Moreover, the results are also obtained for the rest of the amplitude 0.9 < A < 1. The relative error measure in this paper is 0.03% for A = 0.9 while the relative errors obtained by Febbo (2011) and Beléndez et al. (2012), were 3.53% and 0.60% respectively. On the other hand, Belendez et al. (2012) did not obtain approximate period for 0.9 < A < 1. In this article, the approximate periods have been determined in the range of value 0.9 < A < 1 and they have provided better results than the existing result of Febbo (2011).

This study describes the digestive enzyme profiles from foregut contents of the blue swimming crab, Portunus pelagicus (L.), from Straits of Johor, Malaysia. Adult male (mature and immature) and female (ovarian maturation stages 1–4) blue swimming crabs were assayed for the presence of digestive enzymes (protease, trypsin, amylase and lipase) in the foregut. The results show that in some instances, significant differences in enzyme activities were observed between the sexes of P. pelagicus. Protease, trypsin, and amylase were detected in all gonad maturation stages, suggesting that crabs including immature males can readily digest dietary protein and carbohydrates, but not lipids. Trypsin (except for ovarian maturation Stage 4) and lipase (ovarian maturation Stage 4 and mature male only) activities were considerably higher than amylase, indicating that dietary proteins and lipids are more important than carbohydrates and, thus, suggests a carnivorous diet. In conclusion, the changes in enzyme activities between the different maturation stages and sexes reflect natural changes in diet and feeding abilities of P. pelagicus.

Let G be a graph of order n. A subset S of $V\left(G\right)$ is a dominating set of G if every vertex in $V\left(G\right)⧹S$ is adjacent to at least one vertex of S. The domination polynomial of G is the polynomial $D\left(G\text{,}x\right)={\sum }_{i=\gamma \left(G\right)}^{n}d\left(G\text{,}i\right)x^i$, where $d\left(G\text{,}i\right)$ is the number of dominating sets of G of size i, and $\gamma \left(G\right)$ is the size of a smallest dominating set of G, called the domination number of G. We say two graphs G and H are dominating equivalent if $D\left(G\text{,}x\right)=D\left(H\text{,}x\right)$. A graph G is said to be dominating unique, or simply $D$-unique, if $D\left(H\text{,}x\right)=D\left(G\text{,}x\right)$ implies that $H\cong G$. The goal of this paper is to find a new approach to determine the dominating uniqueness of graphs. In this paper, we define a new graph polynomial, called star polynomial, and introduced an analogy notion of star uniqueness of graphs. As an application, if G is a graph without isolated vertices, we show that a graph G is star unique if and only if $\bar{G}\vee K_m$ is dominating unique for each $m⩾0$. As a by-product, the dominating uniqueness of many families of dense graphs is also determined.

The activated carbon doped by nickel oxide (NiO/AC) was prepared using solid reaction. The obtained powder was characterized using X-ray diffraction (XRD) and infrared spectroscopy (IR). The NiO/AC was also used to catalyze the electro-oxidation of phenol at carbon paste electrode (CPE) using electrochemical approaches. Kinetic parameters of phenol oxidation (as the electron transfer coefficient, diffusion coefficient and heterogeneous rate constant) were investigated. The results confirm that phenol oxidation is catalyzed by nickel oxide, due to resonance, steric and aggregation effects.

The experimental conditions were optimized by varying chemical and electrochemical parameters, which involve the oxidation of phenol. The electrode NiO/AC–CPE exhibits a good linear range from 1.0 × 10⁻⁶ mol L⁻¹ to 8.0 × 10⁻⁵ mol L⁻¹ and 1.0 × 10⁻⁴ mol L⁻¹ to 1.0 × 10⁻³ mol L⁻¹ with a limit of detection of 7.09 × 10^–7 mol L^–1 (signal (S) to noise (N) ratio, S/N = 3). This modified electrode NiO/AC-CPE offers a considerable improvement in voltammetric sensitivity toward phenol determination, compared to the unmodified electrode (CPE). The selectivity of the NiO/AC–CPE in detecting phenol was investigated for a number of ions (Cu²⁺, Cd⁺², Ag⁺_, Pb²⁺, Zn²⁺, Fe³⁺, Ni²⁺, Al³⁺, Mg²⁺, Ag²⁺ and Cr³⁺) and biomolecules (4-nitrophenol, dopamine, 2-nitrophenol, paracetamol, hydroquinone, catechol, resorcinol, 4-aminophenol and 3-aminophenol). The proposed method was successfully applied to phenol determination in tap water and olive oil.

The soluble form of starch nanoparticle (SNP) is used for its advantage to encapsulate the antibiotics. In this study, SNP encapsulated antibiotics were introduced to the bacterium, Streptococcus pyogenes and the inhibitory effect was studied. The preparation of SNP loaded antibiotics was carried out using microemulsion nanoprecipitation method which does not require sophisticated equipment, hazardous reagents and extreme conditions. The starch was dissolved in urea alkaline solution and precipitated in ethanolic emulsion system which yields smaller sized nanoparticles with larger surface area thus increasing the efficiency of low water soluble drug molecules loading. The SNP obtained are not vulnerable to clumping. The antimicrobial study was done using the disk diffusion test with different amounts of starch loaded with antibiotics. The encapsulation of single/multiple antibiotics and their inhibition is an indicator of the efficacy of SNPs. This study improved the effectiveness of drugs capability that are produced from a cheap source that brought about a large impact.