Journal of Basrah Researches (Sciences)

Abstract
The detailed mathematical model for the evolution of uniformly distributed voltage in RF-excited partial Z-fold CO2 waveguide laser with common elec- trodes excited by a same RF source is discussed. In the experiment, we studied the voltage distribution along the electrodes. The length of the partial Z-fold channel is 3x460 mm (long channel) and that of the single channel is 460 mm.

Abstract
This paper deals with the Dormand-Prince 8(5,3) algorithm to analyze two classical nonlinear systems, namely the parametrically damped pendulum and driven damped oscillator , and represents the Poincaré sections in two different ways. The basin of attraction illustrates the changing of the status for the system according to the choosing of the initial conditions. Many of algorithms like Euler, Runge-Kutta 2&4, Runge-Kutta Fehlberg, Extrapolation, Cash-Karp, Adams-Bashforth-Moulton4, Gear & Implicit Gear, Hamming, Milne and Heun show unstable solutions for our systems. The Dormand-Prince8(5,3) algorithm shows a stable solution for big values of integration step size of the time, in comparison with other algorithms.

Abstract
Using linear wave equation and Keller-Kolodner method, a new equation is derived for an oscillation of a bubble in an incident sound field. It includes the effects of acoustic radiation, the effects of viscosity, surface tension, compressibility of the liquid, and evaporation and condensation at bubble wall. Where, the liquid temperature at bubble wall is assumed to be constant and that the gas inside the bubble is only vapour. The classical approach to the analysis of the pulsations of a gas bubble is to assume that the pressure within the bubble follows a polytropic relation. In this study, a new formulation of the dynamics of a bubble is presented in which the internal pressure is obtained numerically. Numerical results for vapour bubble in water are presented. A good agreement is found between the theoretical result and the experimental data of the bubble radius. The new equation of the bubble radius can be used to study the bubble oscillation in acoustic fields.

Abstract
In this paper we investigate the asymptotic stability of an equilibrium solution of the differential algebraic equations (DAEs) effected by the Lyapunov-Schimdt reduction. The main conclusion of this paper is that, under the hypothesis , the stability or instability of an equilibrium solution (x0, y0, ) of the DAEs is determined by the sign of DyG where G is the reduced function obtained by the Laipunov-Schimdt reduction.

Abstract
In this paper we study one of the sixteen classes of almost Hermitian manifold, which is the almost Kahler manifold. We found its structure equation and the components of its Reimannian curvture tensor and then we proved that an almost Kahler manifold is parakahler manifold (of class ) if and only if it is Kahler manifold.

Abstract
We Will relate the Behavior of derivatives of the near best approximation to the Ditzian - Totik modulus of smoothness of the functions in .

Abstract
Three soil moisture depletion treatments of 10% (M1), 25% (M2) and 50% (M3) of field capacity were used in a loamy sand soil. Moisture loss from bare soil by evaporation, transpiration and water consumptive use by barley grown in plastic pots was calculated using the soil moisture depletion method. There was a remarkable increase in water consumptive use with time , the highest values were recorded at the productivity stage for all moisture treatments. The M1 treatment gave significantly higher total water consumptive use value (423) mm than the values 298 and 183 mm for the M2 and M3 moisture treatments, respectively. Moisture loss values from bare soil by evaporation from sowing to maturity stages were 266, 156 and 109 mm for M1, M2 and M3, respectively. The low values of the top and grain yield dry weights were related with the small amount of water available for plant use in the soil. The highest reduction in water consumptive use by plant and yield dry weight were recorded in M3 moisture depletion treatment, which was attributed to the adverse effect of water stress during the growing season and seed formation. The highest water use efficiency was calculated for the M2 moisture treatment. The amount of water lost by evaporation from bare soil was higher than the amount used by the plant. This can be related with the availability of pore spaces in the loamy sand soil for air and water movement, which eventually reduce the amount of water available for plant use in the soil. The M2 moisture depletion treatment gave highest water use efficiency values. The highest monthly and daily water consumptive uses by plant were recorded during the maturity and seed formation stages. They were respectively, 129 and 5.25 mm for M1, 90 and 3.50 mm for M2 and 77 and 2.48 mm for M3.

Abstract
The enumeration of sulphite-reducing clostridia from water upon modified DRCM was evaluated against DRCM and RCM using 80 samples of treated drinking waters and river waters with or without heat treatment of the samples. The recoveries of presumptive sulphite-reducing clostridia were significantly higher on modified DRCM (85.7% on drinking water and 81.25% on rivers), while 48.75% and 28.5% respectively on DRCM, and 31.25% and 21.45% on RCM. Heat treatment of samples to 70 C˚ for 10 minutes prior to filtration reduced both clostridia and background on modified DRCM but did not affect counts on DRCM. Four species were identified as Clostridium perfringens, C. baratii, C. ramosum, and C. difficile.