Tikrit Journal of Engineering Sciences

A theoretical analysis based on the numerical solution of the beam impact integral equation is carried out to determine the impact force and deflection time histories, the strain energy absorbed by the beams and the maximum bending moment. Effect of beam boundary conditions on impact response of beam is also discussed. The theoretical results obtained in the present analysis are compared with experimental and theoretical works previously done. A good agreement is found between theoretical and experimental results. This indicates that the impact resistance of relatively large beams may be predicted by using the theoretical approach based on equation of undamped beam vibration. All the derivations required to predict the effect of boundary conditions are performed for both forced and free vibrations. For the same falling mass and the same applied kinetic energy (height of drop) for all cases, the maximum central deflection and the maximum impact force are affected by the boundary conditions of the beams

An experimental hydraulic model investigation was conducted to evaluate the performance of a stepped overflow spillway . The spillway tested has a standard ogee profile with continuous steps cut into a straight portion of downstream face from tangential point (P.T) to the toe . Five constant dimensions (h/l=1.4) steps were used . The objectives of the study are to evaluate the effectiveness of steps on the amount of energy loss under nappe , transision and skimming flow regime . A preliminary comparison with a standard spillway (WES) , that the average increase in energy dissipation at toe is approximately 37% , that would imply a significant reduction of the size of downstream stilling basins . The experimental results indicate that dissipation is highest for the small values of yc/Nh tested (i.e at nappe to transition flow) , also the dissipation ratio increase with increasing N . However , the results are compared to the earlier investigation , for commonly used ranges of the steps and flow condition a general relation is established between the energy loss and the parameter yc/Nh , which may be useful as a predictive formula in a practical applications .

In this study the nonlinear transient dynamic analysis of reinforced concrete slabs using the finite element method is presented. Eight-node Serendipity degenerated elements have been employed. This element is based on isoparametric principles with modifications, which relax excessive constraints. The modifications include reduced order integration to overcome the shear locking. A layered approach is adopted to discretize the concrete through the thickness. Both an elastic-perfectly plastic and strain hardening plasticity approaches have been employed to model the compressive behavior of the concrete. A tensile strength criterion is used to initiation of crack and a smeared fixed crack approach is used to model the behavior of the cracked concrete. Tension stiffening in concrete is assumed such that the concrete can take some tension after cracking. Implicit Newmark with corrector-predictor algorithm is employed for time integration of the equation of motion. Several examples are analyzed using the proposed model. The numerical results showed good agreement with other sources.

In this research ,the regeneration process of the positive ionic exchangers (positive resins) was carried out by the use of (HCl) at various concentrations and forms . Laboratory results showed a large improvement in the efficiency ( i.e the operating time is increased from 12 to 39 hours ). However various mixtures of HCl and H2SO4 are used in order to eliminate the formation of calcium and magnesium sulfate which are formed when H2SO4 is used alone .

The energy of solar intensity is very important in our life, not only for industrial and human needs, but also for living beings on earth. One of the advantages of solar intensity is using it in heating and cooling field in a number of activities among them the passive use. Thus can be done by using storage wall called (Trombe Wall). The effective of glass layers have been studies they are used to cover trombe wall from outside to measure its performance, selecting four conditions(i.e) (non-covering, single, double, and treble layers of glasses). The study shows that trombe wall in second condition with dimension (4x3x.29) m3 gives the best result in heating a room with dimension (4x4x3) m3. Under an environment condition of Baghdad city in Jan., 1994 in comparison with the other conditions. The average room temperature was approximately 26.75oC, it is among within included in average temperature allowable range (23- 27) oC. But the systems of heating in the third and fourth conditions have heat capacity higher than the demand; they can be adjusted to be suitable for their room if reducing the thickness of the wall until gives an among within included an average temperature allowable range .

This research aims the study of utilizing the industrial wastes (solid wastes /lime) for the improvement and stabilization of engineering properties of expansive clayey soil. The soil under study is taken from the location of Al-Nahrawan district-Mosul- city and is described as an appropriate for foundation layer or layers under foundations of roads and facilities because its weakness and its high swelling. It was classified as type (CH) according to The Unified Classification System, the percentage of fine particles was (91%) . This type of soil was treated by using four percentages of industrial wastes of soil weight (2%, 4%, 6%, and 8%), the wastes were obtained from the factory of sugar and ferment in Mosul . The study shows that increase of wastes in the soil decreases the plasticity index of soil (PI) and the soil became Non –Plastic (N.P) at (6%) of wastes. It was shown that the different concentrations of industrial weight in the soil lower the rate of ion exchange and the percentage of upheaval in the soil which was stabilized at 6%. Besides, it was shown that the industrial wastes increase the alkalinity of soil to its maximum. The results of the compaction tests showed that treating soil with industrial wastes led to the increase in the optimum moister content and decrease in the maximum dry density, as far as the lime waste increase the unconfined compressive strength and the shear strength parameters (angle of internal friction (ǿ) and cohesion (ć)). Accordingly, the industrial wastes (lime wastes) may be considered advantageous in effect to the engineering characteristics of finer soil and these wastes can be utilized in groundwork for roads especially for cheap and temporary ways, and it can be used in refilling ground works for buildings .

A theoretical study has been conducted on mixed convection heat transfer of the flow through a horizontal annulus the outer surface heated with an axial uniform heat flux while the inner surface cooled at constant surface temperature. Theoretically the governing equations for a flow were reduced to four equations, which are continuity equation, radial and tangential momentum equation, axial momentum equation and vorticity equation in which the variables were the temperature, vorticity, stream function and axial velocity. These equations were reduced to dimensionless equations in which Reynolds, Prandtl and Rayleigh numbers were presented. These equations were solved numerically by using the marching process explicit finite difference method and Gauss elimination technique after changing the elliptic type energy and momentum equations to parabolic form by adding the change with time for each variable to the left hand side of these equations. Numerical results for the annuli heated by a uniform heat flux in the fully developed region were obtained and represented by stream function contours and isotherms for different values of Rayleigh and circumferential distribution of local Nussult number. The results were based on the fact that the secondary flow created by natural convection has significant effects on the heat transfer process, and reveal an increase in the Nussult number values as the heat flux increases in the horizontal position.