Tikrit Journal of Engineering Sciences

Construction projects have a unique nature which takes the high risk due to many interrelated parameters. This study aims to investigate and assess the influence of the risk factors that occurred during the lifecycle of a school project which comprises the design phases, implementation and operation and maintenance. In addition to examining the effects of the internal and external risk factors that contributed by the school's construction, in order to avoid the risk occurrence during the lifecycle of the projects. A questionnaire was prepared and distributed to a number of engineers in the Governmental Sectors (School buildings sector, Kirkuk Governorate sector, and Municipal sector in Kirkuk Government and Buildings sector in Erbil Governorate) in northern Iraq. The collected data which were analyzed using the relative importance index (RII) and matrix analysis to prioritize the project risks. The analysis results were revealed that the most significant risk factors in the school’s project lifecycle and construction were providing a proper water supply and storage system to maintain a continuous good quality of water, incompetent contractors and sub-contractors for completing school buildings, using proper construction materials to avoid cracks in the building, lack of safety in project site, keep the toilets clean to avoid diseases, and providing an emergency exits were considered the most significant risk factors in construction of school buildings.

The porous media has a significant impact on the heat transfer and storage properties. The present study focuses on the heat transfer of the mixed convection through a circular tube that filled with a porous media at different angles using a neural network. An experiment had been performed for the Rayleigh number range from 108.54 to 907.73 and the Peclet number range 30.3.-510 using three tests for the heat flux. The result shows the mean relative error about 7.913% and the coloration coefficient (R2) Is 99.18% for the train data. The mean relative error about 6.641% and the R2 is 99.46%, for the test data. The results showed that effectiveness of ANN in the predicted thermal performance in thermal engineering applications such as heat transfer modeling using porous media with airflow.

The main objective of this research is to investigate the structural behavior and strength of reinforced reactive powder concrete beams with a hollow section subjected under two point concentrated loading. The experimental work consist of ten beams with dimensions (150mm width×200mm height×1000 mm length), eight of them are hollow beams and two solid beams were cast and tested up to failure. The major parameters adopted in the current research includes the hollowness ratio (10% and15%), hollow location (at top or at bottom), and hollow shape (circle or square). The amount of longitudinal and transverse reinforcement, concrete strength and the other parameters were kept constant for all the specimens. The comparisons between all specimens (hollow and solid) are based on the load carrying capacity, deflection, crack pattern and mode of failures. Results showed that the strength capacity of hollow beam when the hollow lies in the bottom is much higher than for top hollow, and the square hollow will lead to more decrease in the beam strength compared with the circular hollow and this is more evident when the hollowness ratio increases from (10% to 15%).

Crude oil desalting is the first processing step in a refinery. The objectives of crude desalting are the removal of salts, solids, and the formation of water from unrefined crude oil before the crude is introduced in the crude distillation unit of the refinery. The experimental work is divided into three schemes covering the effect of surfactant dosage, test different types of surfactants, and the effect of salt content on desalting efficiency. The results show that the crude oil desalting efficiency, increased with increasing surfactant quantity. The results indicate that desalting efficiency has lowered with increasing the salt content in crude oil. Also, the results show that the best solvent was toluene, and the best mixing ratio of solvent was 10 Vol. %.

Utilization of CO2 in flue gases for the production of sodium bicarbonate is an environmentally friendly process. A mathematical model was constructed for the design and simulation of utilizing a low concentration CO2 (2-18%) in flue gas to produce sodium bicarbonate in a bubble column reactor. The model is based on the mass balance equations for three phases (gas, liquid, and solid). Danckwerts theory for mass transfer from the gas phase to the liquid phase coupling with chemical reaction, and crystallization mechanism was used. The effect of process variables; gas molar velocity or flux (G=2.5-10 mole/m2.s), liquid mass flow rate (mL=2800-3400 kg/h), sodium bicarbonate concentration (x1=0.04-0.1), CO2 gas mole fraction (y=0.02-0.18), column height (h=11-33 m), and column diameter (dR=1-3 m) on the objective variables; solid molar velocity (S), CO2 conversion, precipitation zone height (Zi), and crystal size distribution (CSD) were studied. The conversion of CO2 varied from 34% to 71% whereas the particle size range varied from 0 to 400 μm. The particle size range and the CO2 absorption efficiency of about 50% for 20 m column height are in agreement with the literature.

Driving vehicles on curved roads is dangerous because of the risk of accidents. This is due to the centrifugal force, gyroscopic moment and hydroplaning of the vehicle, ending with vehicle slipping or tipping. The aim of this research is to find the critical speed under any one of the above mentioned risks. The water pressure under the vehicle tires was calculated using Matlab R2017a in order to find the pressure value that able to lift the vehicle causing slipping and then going out of control. The effect of many parameters, on the vehicle hydroplaning have been studied. These parameters are tire width, wheel load and water layer thickness. While for vehicle slipping due to the centrifugal force or the gyroscopic moment, the following parameters have been studied. These parameters are height of vehicle gravity center, vehicle width, radius of the circular path, and track angle. The results showed that the gyroscopic torque negatively affects the critical velocity of the vehicle, and it reduced it about 0.549%.The centrifugal effect is the has the greatest influence on the gyroscopic effect, and the gyroscopic effect pushes the vehicle outward and increases the radius of the rotation, while the gyroscopic couple effect ,at low radius. of low rotation, is very small. Gyroscopic impact is increased by increasing the radius of the rotation path. The result also showed the increase of the road surface angle and surface at the turning the influence positively on the safe speed of the vehicle at all the above variables.

This Study is an empiric- analytical research in city planning discipline was conducted in Sulaymaniyah city from Dec. 2015 until July 2017. Geographically Sulaymaniah situates north-east of Republic of Iraq. Like many other urban centers, Sulaymaniyah city as one of the congested urban areas in Kurdistan Region, is almost over populated and congested, resulting in accumulated problems in health-, economical-, services, technical-, social- and planning affairs, which leads to permanent degrading of the natural, and social environment and thus impact on the quality of life, Thus the main concern of this study is firstly finding out the reasons facts indeed responsible for the above described unsatisfied situations and then try to answer the questions whether planning methods (if any) manage to prepare answers to these urgent problems overwhelming the city? The study believes that the cardinal reasons for this situation are the effects of combinations of triple facts, namely: the exponential growth of human population in general- and accompanied problems-, the destroyed balance between rural and urban areas and the political vision of administrative machinery that focus on urban centers by neglecting countryside. The cumulative effect of these facts could be observed in form of many distinctive and at the same time interlocking elements leads to the problems that mentioned above. Among many elements involving, the study handles, analyzes and discusses only the elements indeed responsible for destroying the visual, physical and health conditions of the city inhabitants in Sulaymaniyah. Used criterion in determining these elements are the terms: active element, Passive Element, Critical element, and buffer element, which give the adequate answer to the arise questions .