المجلد الثامن - العدد الاول - يونيو 2018

Effect of Dhanoun (Cistanche phelypaea L. Cout) on the Performance of Some Cultivated Chenopodiaceous Plant Species

2018-01-01T00:00:00Z

Effect of Dhanoun (Cistanche phelypaea L. Cout) on the Performance of Some Cultivated Chenopodiaceous Plant Species Awad Fageer Farah Dhanoun (Cistanche phelypaea L. Cout, family Orobanchaceae) is an obligate root holoparasite on certain wild members of Chenopodiaceae, Zygophyllaceae, Tamaicaceae and Capparaceae. However, Chenopodiaceae accommodates more host plants compared to the other three families. An outdoor pot experiment was carried out to study the effect of dhanoun on four cultivated chenopodiaceous crop species, namely atriplex (Atriplex leucoclada Boiss), beet (Beta vulgaris subsp. vulgaris L.) , chard (Beta vulgaris subsp. cicla (L.)), spinach (Spinacia oleraceae L.).The studied growth traits (plant height, root length, biomass) of all tested crop species, except spinach, were significantly (P < 0.01%) affected by Dhanoun. The reduction in biomass of the tested crop species, as a result of the effect of the parasite, ranged from 0.0% with spinach to 52.0 % with atriplex. Thus, based on their general performance, under the influence of Dhanoun, the tested crop plants could be ranked as follows: atriplex > beet > chard > spinach. The damage caused by the parasite (Dhanoun) appears to be of a greater magnitude on atriplex followed by beet, and a lesser magnitude on chard. However spinach was not affected by the parasite. In this study, dhanoun was found to attack only biennial and perennial host plants, it seldom attacks annual ones.

The Effect of Current Density, Time and Anodizing Temperature on The Local Burning of Anodic Alumina Films

2018-01-01T00:00:00Z

The Effect of Current Density, Time and Anodizing Temperature on The Local Burning of Anodic Alumina Films Ali K. M. Al-zenati The local burning phenomenon on the surface of the anodic alumina films is studied under wide range of current densities, anodizing times and anodizing temperature. The growth of nodules occurs at low anodizing temperature (0 0C) and at relatively high current density (10-40 mA/cm2). However, the local burning does not obtain at low current density i.e. 5 even at 0 0C. Moreover nodules formation is not existed on the surface of the anodic alumina films fabricated under the same previous anodizing conditions (5-40 mA/cm2) but at high anodizing temperature (20 0C). In fact, the increment of current density, voltage or electric field increases the local heat. Dissipation of local heat plays big role to prevent local burning rather than reduction of anodizing temperature. Therefore heat transfer is more important than decreased temperature of the electrolyte only which is enhanced the local burning. No obvious effect of anodizing time on occurrence of local burning because of the initial growth of nodules forms at the first seconds of anodizing time. The initial behavior of the voltage-time response and the ∆V/∆t-time transient is a good indicator for nodules growth.

Fracture Toughness for Ductile Materials Under Low Constraint Conditions

2018-01-01T00:00:00Z

Fracture Toughness for Ductile Materials Under Low Constraint Conditions Osama A. Terfas; Reda B. Areibi; Abdulbaset M. Kraima The crack tip stress field for low constraint conditions arising from short cracked bars, thin cracked bars, and across the thickness of the bar itself is examined. The reduction of crack tip stresses is correlated with the fracture resistance. The material failure curve that correlates the critical fracture toughness with the mean stress is constructed. It is observed that testing deeply thin geometries would provide similar fracture resistance to that measured on shallow cracked thick geometries. Fracture toughness data obtained from finite elements analysis were consistent with the experimental fracture data. The ductile fracture resistance defined as tearing modulus (TR=∂J/E∂a) reveals that fracture data obtained from different cracked geometries have similar effect on crack tip constraint. This investigation emphasised that fracture toughness is strongly influenced by the level of stress. The finding of this research of low constrained geometries is essential in structural integrity assessment as it quantifies precisely the stress condition and the fracture toughness, inherently avoiding the unnecessary replacement.

On Some Numerical Methods for Solving Fredholm Integral Equations with Continuous Kernel

2018-01-01T00:00:00Z

On Some Numerical Methods for Solving Fredholm Integral Equations with Continuous Kernel Joud M. Abdelaziz; Haniyah A M Saed Fredholm integral equations with continues kernels arise for instance in the boundary integral equations either directly or as a result of treating different kinds of singular kernels using some regularization techniques. Here, we show a comparison of the convergence of two well-known numerical methods for solving integral equations. These methods are the collocation method and the Galerkin method. An illustrated examples for second kind Fredholm integral equations of continuous kernel show that the collocation method seems to converge faster than the Galerkin method.