Tikrit Journal of Engineering Sciences

Presented in this paper are stress and load factor charts for floating tandem axles acting on the interior of concrete pavement slabs resting on Reissner’s foundation. The floating tandem axle consists of dueled single axle followed by a single tired single axle or vice versa. The geometrical characteristics of the floating tandem axle were obtained from an axle load survey in Iraq. Based on the survey results, the floating tandem axle load frequency distribution histogram together with that for tire pressures were obtained. Circular tire-pavement contact areas between the tires of the floating tandem axle and the concrete pavement slab were assumed. The chart for the bending moment in concrete pavement slabs on Reissner’s foundation developed by Reddy and Pranesh[1] was used to determine the maximum bending moment due to interior loading by a floating tandem axle. The stress and load factor charts were developed for various slab thicknesses of 6, 8, 10, and 12 in. (15.24, 20.32, 25.40, and 30.48 cm). Using the developed stress charts, the maximum bending stress in the concrete pavement slab can be obtained directly for given floating tandem axle load and slab thickness.

Based on node flow analysis the available nodal flows under deficient conditions is presented for determining the reliability of water distribution system (WDS). The reliability is concentration on a node-reliability factor. Volume reliability factor, and network-reliability factor. Even though reliability of WDS depends on several parameters, only variation of consumption in daily, demand excess, and element failure conditions are considered. Computer programs have been written to determine the aforementioned reliability factors. The procedure is described and illustrated through an example.

This paper considers the time-varying behavior of composite steel-concrete beams with rigid or flexible connections under service loads. The age-adjusted effective modulus approach is used with evaluating the aging coefficient “χ” in absence of connection and characterized by a theoretical point of view. For a simplified expression to evaluate “χ” and for an easy method to implement, a closed-form solution in the hypothesis of rigid connections and uncracked concrete is proposed. The method is verified by comparing with the results of another finite element model.

A finite element model for the study of the creep, shrinkage and tensile stiffness between cracks effects in partially prestressed continuous composite beams with deformable shear connections is proposed in this paper. The algorithm used is very general and allows the adoption of an arbitrary viscous law expressed in integral form and any load history. By means of simple numerical comparisons, the potentials of the proposed formulation are shown. This model, due to its simplicity, can be easy implemented in an analytical program.

The study aims to estimate causes for 316L stainless steel tubes failure in chloride contaminated environment. All the conditions were established and studied like temperature difference, thermal stresses, oxygen content and chloride concentration. All the observations on the performed tests suggest that chloride does not affect 316L stainless steel cracking deeply, but there was a conjugate effect appeared when thermal stresses exists.Uniform corrosion was observed in the case of oxygen film absences. Visual and microscopic inspections have been used to observe the effect of chloride and oxygen concentration on corrosion form.

This paper presents a state estimation technique for speed senseless field oriented control of induction motors. The theoretical basis of each algorithm is explained in detail and its performance is tested with simulations using MATLAB package VER.6.3. A stochastical nonlinear state estimator, Extended Kalman Filter (EKF) is presented. The motor model designed for EKF application involves rotor speed, dq-axis stator currents. Thus, using this observer the rotor speed and rotor fluxes are estimated simultaneously. Different from the widely accepted use of EKF, in which it is optimized for either steady- state or transient operations, here using adjustable noise level process algorithm the optimization of EKF has been done for both states; the steady-state and the transient-state of operations.

This study was undertaken to evaluate the hydraulic performance of stilling basin with unusual shapes of baffle blocks. Seven groups of baffle blocks were selected for this purpose , these blocks were cut within a different forms, three of these groups were cut with angle (15o, 30o, 45o) horizontally. Another three groups were cut with the same above angles, but vertically. The seventh group was cut with semi-cylindrical section (shown from side view). For a comparison, standard trapezoidal baffle blocks were used. Dimensional analysis technique was used to obtain the dimensionless parameters of hydraulic performance of the cutting baffle blocks and the drag force applied on these blocks. Laboratory experiments were carried out on one raw of the cutting baffle blocks for each model. The results indicated that the cutting baffle blocks are generally better than the standard blocks in dissipation of a hydraulic energy and reduction of a hydraulic jump length, but a ratio of drag force applied on cutting baffle blocks was greater than this ratio on the standard blocks. For the same flow conditions and angle of cut, the baffle blocks of vertically cutting gave a better results for energy dissipation and reduction in the length of the hydraulic jump than the baffle blocks of horizontally cutting, but the drag force applied on the baffle blocks with a vertically cutting was greater than applied on a blocks with horizontally cutting. Also, the results indicated that an agreement in the hydraulic performance between the baffle blocks which were cut at (45o) vertically and the baffle blocks of semi-cylindrical cutting. The cutting baffle blocks gives a greater value of the energy dissipation which was (80.62%) than the standard blocks and greater value of reduction in the hydraulic jump length which was(37.5%),also these blocks gives maximum increase of the drag force ratio which was (97%) greater than its value on the standard baffle blocks.

An irrigation scheduling model was developed based on daily soil water balance which takes into account the effect of water table on irrigation water requirement for wheat crop at Mosul area for eleven years. Capillary rise of water table was estimated with Darcy’s equation .Crop evapotranspiration was estimated by pan evaporation method. The model inputs are daily climatological data for eleven years at Mosul Station, soil data (total available water, field capacity, permanent wilting point, allowable percent depletion, saturated hydraulic conductivity),and crop data(root depth for wheat crop, crop coefficient).The model estimates daily and seasonal actual evapotranspiration, effective rainfall, irrigation requirement and upward capillary rise from water table. Using the model for wheat, the seasonal irrigation requirements were reduced by 40% for silt loam soil and 90% for loam soil ,avoiding crop water stress or excessive irrigation.

Wide laboratory search was done to evaluate brick units in single, and test the prisms built from brick unit by use ultrasonic waves in non-destructive test. The results show that the pulse velocity increases with increasing compressive strength and time of construction. From this paper we can estimate compressive strength for building unit by find the equation of the curve ,then we can estimate compressive strength for building sample, for example bricks from pulse velocity of ultrasonic waves without need destructive test.

The present research comprises the design of a scientific educational program by computer, it is represented by preparing a group of main windows and other secondary windows, this program was written via using visual basic language to educate students the multi-types of thermal cooling load sources and how to calculate it for different buildings for both the students and the designing engineer by using the equations and tables which were prepared for this purpose. This program consists of (15) main windows and (10) secondary windows for help, the first one is specified for the title of the program and the purpose of its preparing, the second main window until the eleventh are specified to enter the required data, while the main windows from number twelfth to fifteenth are specified to review the results as tables and graphs and to review a summary report about the peak cooling load of the building. The user can enter the secondary windows from the main windows which are specified to produce the help to the students or the users of the program about the meaning of the cooling load and its sources and how to calculate it in an explicit by using equations and the required tables.