Tikrit Journal of Engineering Sciences

Basic traffic elements (flow, speed, density) are used in many stages of transportation process. Flow-speed-density relationship isan important concept, which translates traffic stream characteristicsinto mathematical or statistical rnodels. These models are widely usedin transportation engineering. The main objective of this research is finding out the nature of the relationships between the basic traffic elements characteristics for multi-lane highways in Baghdad city. Data has been collected throughout an extensive field survey on twenty selected sections in the study area. Photograph technique is usedto deterrnine the basic traffic elements. Statistical technique is applied analyze the collected data in order to present the best models to describe flow-speed-density relationships. The results of this study indicate that the linear relationship between speed and density is signification with confidence level (99%). The nature of this relation is considered during theformulation of the other relation-ships between traffic elements.

Road traffic noise is a function of basic traffic element (flow, speed, density) and percentage of heavy vehicles. The recognition of traffic noise as a one of the main sources of environmental pollution has led to the development of statistical models that enable the prediction of traffic noise level from fundamental variables of basic traffic element. The main objective of this research is finding out the effects of these elements on traffic noise levels for multilane highways in Baghdad city. Data has been collected throughout an extensive field survey on twenty selected sections in the study area. Noise levels were measured by using sound level meter in five stations in each selected road and the noise level reading was taken at each ten seconds, the reading of sound level meter was recorded directly, then the noise levels were determined ( L10, L50, L90, Leq). Statistical technique is applied to analyze the collected data by the aids of computer program packages in order to present the best model to describe the influence of flow, speed , density and percentage of trucks on traffic noise levels. The results of this study indicate that the second and third order equations are the best models that represent the effect of each traffic element on each traffic noise level in general, and especially on L16 noise level.

This study is an application of optimization method to the structural design of tunnels, considering the total cost of the tunnels as an objective function with the properties of the tunnel and soil unit weight, height of soil above tunnel, height of water above tunnel and tunnel radius, as design variables. A computer program has been developed to solve numerical examples using the ACI code equations , requirements and criteria in concrete design. The results shown that the minimum total cost of the tunnel increases with the increase of the soil unit weight and tunnel radius, and decreases with the increase of the height of water above tunnel.

Induction motors (IM) arc characterized by complex, highly nonlinear time varying dynamics and inaccessibility of some states and outputs for measurements and hence may be considered as a challenging problem. Field orientation control (FOC ) methods of an induction machine achieve decoupled torque and flux dynamics leading to independent control of torque and flux as for separately excited DC motor, but there are sensitive to motor parameter variations. The present work select the indirect field orientation control (IFOC) as an effective method for eliminating the coupling effect. The results showed how well the drive performance has been improved by this control strategy. However, to what extent the control strategy can perform the decoupling relies on the accuracy of the slip frequency calculation. Unfortunately, the slip frequency depends on the rotor time constant that varies continuously according to the operational conditions and then the coupling effect may again arise. This paper investigates the improvement in the performance of the induction machine dynamics as the IFOC technique is utilized. Also, it investigates the degradation in dynamic performance when the rotor resistance is deviated from its nominal value.

This work was based on the fact that a lot of waste-environmental pollution’s-can be re-used by fabrication in different economical techniques in addition to save the environment from their aggressive effects. The wastes of polyethylene (Pepsi bottles) and black emulation waste(bwb) for petroleum (bitumen) from local street and Iraqi refineries were used in this work to prepare a matrix materials (bwb/As/PE, bwb /Sc/PE)that will suitably used as water proofing lining and wall insulation. Different weight ratios of waste polymer (polyethylene) as(10,20,30.40,50) wt% bwb is used to improve phsiyco chemco-properties and different reinforcement local cheap ceramic materials such as asbestos fiber (As) (5, 10, 15,20,25) vol% and silicon carbide (Sc )(5,10,15,20,25) wt% to improve thermo-mechanical properties of black waste bitumen (bwb). Their effects on both phsiyco-chemco and thermo-mechanical properties (chemical resistance, thermal stability, TG analysis, tensile strength) of both matrices systems (bwb/As/PE, and bwb/Sc/PE) produced achieved optimum mixing ratiowhich gives best properties with less internal stresses had been showed. The result of testing shows that an optimum mixing ratio for sample (3) from both matrices systems (bwb/AsiPE and bwb/Sc/PE) and with excellent pysiyco-chemco and thermo-mechanical properties for system bwb/As/PE system Aging for 7 days,50 °C in different chemical solutions (100% H2O, 5% NaOH, and 5% H2SO4), The results of TG test are: an excellent thermal stability and less loss in weight is for sample (3) reinforced by asbestos fiber where its loss only 5% of original weight at 500 °C compared to sample 3 reinforced by silicon carbide, which its loss 20% of original weight at the same temperature, The thermal conductivity for both samples reinforced by asbestos fiber and silicon carbide decreased with increasing reinforcement agent (asbestos, and silicon carbide ) with excellent results for asbestos sample at 0.009 w/m oC than other one of 0.5 w/m °C. For silicon carbide The mechanical properties tensile load resistance for asbestos sample (3) after aging it in different chemical solutions (100% H2O, 5% NaOH, and 5%H2SO4) for 7 days at 50 °C with rang 100-200 dyne/cm compared to that of silicon carbide sample (3) for range 60-78 dyne/cm respectively.

CHEMCAD process simulator was used for the analysis of existing HF stripping column in LAB plant(Arab Detergent company/Baji-Iraq). Simulated column performance curves were constructed, The variables considered in this study are the thermodynamic model option, top and bottom temperatures, feed temperature, & feed composition, Also simulated columns profiles for the temperature, vapor and liquid flow rates and compositions, were constructed, using different thermodynamic models options, Four different thermodynamic models options (SRK, TSRK, PR, and ESSO) were used, affecting the results within l-25% variation for the most cases, The simulated results show that about 5% of paraffin (C10 & C11) presents at the top stream which may cause a problem in the LAB production plant, The major variations were noticed for the total top vapor flow rate with bottom temperature and with feed composition. The column profiles maintain fairly constants for tray 5 (immediately below feed) through tray 18 (immediately above reboiler). These tfays can be removed without severely affected thecolumn profile. Simulation of the HF stripping column in LAB production plant using CHEMCAD simulator, confirms the real plant operation data, The study gives evidence about a successful simuiation with CHEMCAD’

In this research, a numerical study has been done to done to clarify the effect of the eccentric annulus of to two horizontal cylinders on the rate flow the behavior of the thermal boundary layer at the entrance. The research includes the study of the effect of the eccentric annulus percentage and its directions on the flow behavior when the internal cylinder. The theoretical analysis of the question includes the solving of Naver – Stoke and energy equations on the supposition that the flow is steady, fully developing hydrodynamic, and in the stage of thermal developing. The question has been numerically solved after the transformation of the Cartesian coordinates to the computational domain by applying body fitted coordinates. The results include a survey of the cylinder surface in many sites of annulus flow, where as it is appeared in that the bouncy force causes the secondary flow behaves none uniformly at the entrance. The Nusselt number average along the two cylinders is decreased with the increase of eccentricity as a result of narrowing in the flow area which diminishes the average of heat transfer quality. We also conclude that the increase of Rayleih number with the movement of the heated cylinder towards low causes the increase of the average of Rayleih number and the laminar flow changes to turbulent flow at the limited region of the entrance when Rayleih number increases or the eccentricity percentage with cylinder movement away from the perpendicular halfway axis but the disturbance vanishes in approaching to the fully developed heated region. A correlation relationship is extracted to find an average change of Nusselt number after the stability of flow in the fully developed region when the diameter of the internal cylinder equals to half of external.

In this research a theoretical study for laminar steady natural convection heat transfer through concentric horizontal annulus heated from inside, it’s contain two different fluids (pr1:0.7, pr2:7.0) for radius ratio (5) and for Gr numbers (102-105). A vorticity stream function formula was used in the numerical solution by transforming the governing differential equations into this formula, then turned into algebraic equations solved numerically using (Explicit Successive Over Relaxation finite deference method). To declare the movement of the fluids and the distribution of the temperatures through each of them counters for both streamlines and isotherms through the annulus were used, also the results contain calculating the distribution, of local Nu number along the internal cylinder inside the annulus, also a correlation was found to estimate the amount of heat transfer for both fluids. Through this research it’s found that two separating flows forming above and under the separating interface, also it’s found that the highest local Nu number accrue at the separating interface.

A theoretical study was carried out for transient heat transfer forced convection through horizontal tube filled with porous media. All the properties of the porous media are assumed to be constant in both the radial and axial directions. The governing equations are momentum and energy equation. These were formulated in using polar coordinates system. The results obtained are for three values of the effective Prandtl numbers and dimensionless pressure gradients. Theses gradient are (0.1,0.3,0.9) Pre ,(103 ,104 ,105 )B. The study proved that the thickness of the thermal boundary layer and its length depend on the parameter (B) and the effective Prandtl number. The thickness of the thermal boundary layer began with an increase starting from the front edge (inter section) until the thickness becomes equal to the radius of tube. The increase in Prandtl number gives an increase in the thickness of the thermal boundary layer for the same pressure gradient.

Vacuum residue of Jumboor crude oil above 773 K of specific gravity 1.105 and 6. I wt% sulfur , was treated with commercial pentane &hexane fractions for preparing deasphaltened oil (DAO) suitable for hydrodesulphurization process. Solvent deasphaltening was examined with mixing time 0.25 to 4 h and solvent to oil ratio 4 to 15 ml : 1g at different temperatures . The asphaltenes yield was decreased with increasing mixing time and increased with increasing solvent to oil ratio . Hexane deasphaltened oil hydrotreated on presulfided commercial cobalt-molybdenum alumina catalyst at specified operating conditions in a trickle bed reactor . The hydrotreating process applied at a range of temperatures varied from 623 to 698 K, liquid hourly space velocity (LHSV) from 0.7 to 2.2 h-1 ,H2/oil ratio about 300 liter/liter and hydrogen pressure was 4 Mpa . The results of hydrotreating process indicate high sulfur and metal removal with decreasing LHSV as well as high temperature applied . The kinetic of hydrodesulphurization and demetalization reactions followed 2nd and 1st order reactions respectively .