The effects of solar radiation pressure at several satellite (near Earth orbit satellite, low Earth orbit satellite, medium Earth orbit satellite and high Earth orbit satellite ) have been investigated. Computer simulation of the equation of motion with perturbations using step-by-step integration (Cowell's method) designed by matlab a 7.4 where using Jacobian matrix method to increase the accuracy of result.

In this paper, we made comparison among different parametric ,nonparametric and semiparametric estimators for partial linear regression model users parametric represented by ols and nonparametric methods represented by cubic smoothing spline estimator and Nadaraya-Watson estimator, we study three nonparametric regression models and samples sizes  n=40,60,100,variances used σ²=0.5,1,1.5 the results  for the first model show that N.W estimator for partial linear regression model(PLM) is the best followed the cubic smoothing spline estimator for (PLM),and the results of the second and the third model show that the best estimator is C.S.S.followed by N.W estimator for (PLM) ,the

The effect of the antibiotic cefoperazone was examined. The experiment was conducted on white male mice. The experiment was divided into three groups, 11-12 mice were allocated to each group to conduct different experiments, It was injected Intraperitoneal into the groups for 7 consecutive days. The control group was given distilled water throughout the experimental days. The second group was given the antibiotic cefoperazone at a dose of 500?mg/kg/day. The third group was given the antibiotic cefoperazone 800?mg/kg/day. Cefoperazone affects blood components, causing a noticeable increase in the total number of blood cells, a slight increase in the number of red blood cells, and an increase in hemoglobin and hematocrit. It also caused an in

In 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

<p>The objective of this paper is to study the dynamical behavior of an aquatic food web system. A mathematical model that includes nutrients, phytoplankton and zooplankton is proposed and analyzed. It is assumed that, the phytoplankton divided into two compartments namely toxic phytoplankton which produces a toxic substance as a defensive strategy against predation by zooplankton, and a nontoxic phytoplankton. All the feeding processes in this food web are formulating according to the Lotka-Volterra functional response. This model is represented mathematically by the set of nonlinear differential equations. The existence, uniqueness and boundedness of the solution of this model are investigated. The local and global stability

Bee keping projects is one of the most important agricltural investment projects because it generate profit in a short period . In addition to the multiplicity of products and other benefits . Research aimed at study the feasibility of two projects one hand in the origin of the Al – Mashrok since 2006 , kicking off with ten hives , and the scond proposal , kicking of 100 hives using the criteria of the world bank . Results showed that the bee keeping projects is economically feasible, whether small or large .. Even when the analysis of the sensitivity of the project to changes which may occur in the price of output and resources by reducing costs and increasing revenues by 10% it remains economically viable .

The present study aims to explore determinants of entrepreneurial behavior from perspective of social theory. It is based on model notions of (Tyler & Blader, 2003) which have focused on studying role of positively personal and social identity in motivating employees to practicing desired behavior which serves the organization in which they work. Based on these notions and previous literature, study model were built. This model explains the relationship between status judgments (perceived internal respect and perceived external prestige)  and entrepreneurial behavior. It includes three main hypotheses. The first and second hypothesis are concerning the relationship between status judgmen