Journal of Engineering

The study investigates natural convection in an annular space provided with metal foam fins attached to the inner cylinder. The metal foam fins made of copper were inserted in different axial sections with three fins in each section. The temperature of the inner cylinder is kept constant while the annular outer surface is adiabatic. The thickness effect of the inner pipe wall was considered. The Naiver Stokes equation with Boussinesq approximation is used for the fluid regime while the Brinkman-Forchheimer Darcy model is used for metal foam. The local thermal non-equilibrium condition in the energy equation of the porous media is presumed. The effect of Rayleigh number and number of foam fins in the axial direction on fluid flow and heat transfer characteristics were examined. Results showed that as the Rayleigh number increases, the convection mode becomes more dominant and the average Nusselt number increases. At a Rayleigh number of 10^6, the Nusselt number reached its highest value of 4.6 for the case of adding seven axial metal foams. A comparison between adding foam fins and copper fins showed a significant enhancement in the Nusselt number, with the greatest enhancement percentage being 45.9% at a Rayleigh number of 10^6 for the case of using seven sections of foam fins.

This study investigates the stabilization of expansive soils using waste materials, specifically Cement Kiln Dust (CKD) and waste plastic bottles (WPB). Expansive soils were collected from various locations with a plasticity index (PI) ranging from 15 to 27 and a liquid limit (LL) ranging from 35% to 64%. The stabilizer percentages were varied from 0% to 20%, and curing durations for CKD cases were 7 and 28 days. The results showed that the best percentages of CKD and WPB were 12% each. The study observed a significant reduction in liquid limit (46%), plastic limit (55%), and swelling percent (96%), along with an increase in California Bearing Ratio (CBR) by 98% with the addition of both CKD and WPB. The optimal stabilization materials were found to be a mixture of 12% CKD and 12% WPB after 28 days of curing.

The research focuses on predicting the shear strength parameters of gypseous soils using Artificial Neural Networks (ANN). Two models were developed to predict cohesion and the angle of internal friction based on nine basic soil properties: depth, gypsum content, passing sieve no.200, liquid limit, plastic limit, plasticity index, water content, dry unit weight, and initial voids ratio. The models were trained using a multi-layer perceptron with the backpropagation algorithm. Sensitivity analysis revealed that dry unit weight and plasticity index significantly affect cohesion, while gypsum content and plasticity index significantly affect the angle of internal friction. The models demonstrated good reliability in predicting shear strength parameters for gypseous soils.

This research aimed to develop a simulation traffic model for an urban street with heterogeneous traffic capable of analyzing different types of vehicles of static and dynamic characteristics based on trajectory analysis that demonstrated psychophysical driver behavior. The base developed model for urban traffic was performed based on the collected field data for the major urban street in Baghdad city. The parameter; CC1 minimum headway (represented the speed-dependent of the safety distance from stop line that the driver desired) justified in the range from (2.86sec) to (2.17 sec) indicated a good match to reflect the actual traffic behavior for urban traffic streets. A good indication of the convergence between simulated and field data of maximum error of 8% and below 10% for traffic flow rate and that provided a successfully simulated model by VISSIM for urban traffic behavior. The traffic speed decreased slowly, but still, variation in a large range from (30 km/hr to 55 km/hr) until a flow rate of 1000 vehicles/hr was reached, then the traffic speed decreased sharply. The dispersion between data points was caused by driver behavior and the special characteristics of the urban street. This dispersion of data points reduced and became less significant when it reached the capacity of the road. The obtained capacity value for divided urban traffic streets was (1610 vehicles/hr) with an optimum traffic density of 64 vehicles/km. Traffic simulation utilizing VISSIM parameters had been developed successfully since the simulation could estimate the field capacity with an acceptable range of error of 7.5 % (less than 10%).

The study investigates the effect of distributing steel fibers into the slurry mortar on some properties of Slurry Infiltrated Fiber Concrete (SIFCON). Two sets were used: one with randomly distributed fibers and another with orderly distributed fibers. Crimped steel fibers with an aspect ratio of 60 were used, and two different volume fractions (7% and 9%) were tested. The compressive and flexural strength tests were conducted on standard cubes (10x10x10 cm) and prisms (40x7x7 cm). The results showed that random distribution of fibers yielded better results than orderly distribution, with an increase in compressive strength by 1.5% and flexural strength by 6.9% for the 7% volume fraction, and 23% and 6.5% for the 9% volume fraction, respectively.

This study investigates the impact of different nanoparticles on diesel fuel characteristics. Iraqi diesel fuel was treated with nanoparticles at various weight fractions (30, 60, 90, and 120 ppm). The engine was tested at a constant speed of 1600 rpm. The results showed that ZnO nanoparticles were more efficient than CeO nanoparticles. The best performance was observed at 90 ppm for both types, with ZnO showing up to 34.28% improvement in engine performance and significant reductions in NOx, CO, CO2, and UHC emissions compared to pure diesel fuel. The brake thermal efficiency increased with the additives, with the best improvements being 62% for ZnO and 59% for CeO at 120 ppm.