Journal of Engineering

This study investigates the heat transfer rates of a single horizontal finned tube immersed in a water-filled enclosure tilted at 30 degrees. The results serve as a baseline for a solar water heating system with an immersed heat exchanger2. Tests were conducted under both adiabatic and uniform heat flux boundary conditions. The natural convection flow within the enclosure was interpreted from measured water temperature distributions2. Correlations for the overall heat transfer coefficient in terms of the Nusselt and Rayleigh numbers were derived

This study presents a numerical analysis of developing compressible turbulent flow and heat transfer in a circular tube with uniform injection or suction. The continuity, momentum, and energy equations, along with the (k-ε) turbulence model, were solved using the Finite Difference Method (FDM). The working fluid was air, with a tube diameter of 20 cm and a length of 130 hydraulic diameters. The Reynolds number was 1.78x10^6, and the Mach number was 0.44. The study examined the effects of suction and injection on the hydrodynamic and thermal boundary layers, as well as the resulting changes in velocity profiles, friction factors, Nusselt numbers, and turbulent heat fluxes

This study investigates the effects of variables such as temperature, velocity, and area fraction of metals on galvanic corrosion in systems under mass transfer control, such as seawater (pH=7). The galvanic corrosion of the Fe-Zn couple was analyzed to study the influence of Reynolds number, temperature, and area fraction on the galvanic corrosion rates and galvanic corrosion potential. The results showed that the galvanic corrosion rate of the more active metal (Zn) increased with Reynolds number, while the corrosion rate of the more noble metal (Fe) slightly increased depending on the galvanic potential and area fraction. Increasing temperature led to a shift in the corrosion potential to more negative values and affected the corrosion rate of Zn based on oxygen solubility and diffusivity. Increasing the area fraction of Zn shifted the galvanic potential to the negative anodic direction, while the corrosion rate for Fe decreased

Wireless digital communication is rapidly expanding resulting in a demand for systems that are reliable and have a high spectral efficiency.To fulfill these demands OFDM technology has drawn a lot of attention.In this paper a new technique is proposed to improve the performance of OFDM. The new technique is use the slantlet transform (SLT) instead Fast Fourier transform (FFT) in order to reduce the level of interference.This also will remove the need for Guard interval (GI) in the case of the FFT-OFDM and therefore improve the bandwidth efficiency of the OFDM.The SLT-OFDM is also better than wavelet packet (WP)-OFDM in the selective channel because the slantlet filter bank is less frequency selective than the traditional DWT filter bank, due to the shorter length of the filters and SLT algorithm is faster than WP algorithm.The main results obtained indicate that the performance of SLT-OFDM is better on average by 18dB in comparison with that of FFT-OFDM flat fading channels. For frequency selective fading channel the SLT-OFDM performs is better than the FFT-OFDM on the lower SNR region, while the situation will reverse with increase SNR values

A one-dimensional finite difference model for the simultaneous movement of light non-aqueous phase liquid (LNAPL) and water through unsaturated-saturated zone of the soil in a three fluid phase system with air assumed constant at atmospheric pressure is developed. The flow equations described the motion of light non-aqueous phase liquid and water are cast in terms of the wetting and non-wetting fluid pressure heads respectively. The finite difference equations are solved fully implicitly using Newton-Raphson iteration scheme. The present numerical results are compared with results of Kaluarachchi and Parker (1989)and there is a good agreement between them.The present model can be used to simulate various transport problems in a good manner. Results proved that the maximum LNAPL saturation occurred below the source of the contaminant during LNAPL infiltration. During redistribution, the LNAPL saturation had amaximumvalueat the advancing of the LNAPL infiltration front

This study investigates the steady two-dimensional natural convective heat transfer in a rectangular porous cavity heated from below, with horizontal walls heated to uniform but different temperatures and adiabatic sides. The numerical results of heat transfer rates are presented for porous Rayleigh numbers (Ra) in the range (Ra≤500), with layer aspect ratios (Ar) ranging between 0.5 and 5. Plots of streamlines and isotherms show the behavior of the flow and temperature distribution. The study demonstrates that the Nusselt number is strongly dependent on the porous Rayleigh number and the geometry of the cavity represented by aspect ratios. The porous Rayleigh number significantly affects the flow field, with any increase resulting in a change from unicellular to multicellular flow. A correlation equation is derived to show the dependence of the Nusselt number on the porous Rayleigh number and aspect ratio, which is beneficial for designing thermal insulators in energy storage engineering applications

This study focuses on the implementation of a monitoring system utilizing simultaneous vibration and strain measurements on the tool tip to detect shrinkage and cracks in cast iron workpieces during turning operations. The machining parameters considered include cutting speeds of 116.5 and 136.6 m/min, feed rates of 0.17 and 0.23 rev/min, and a depth of cut of 1 mm. Data from the machining processes were recorded using a piezoelectric strain sensor (PCB 740B02) and an accelerometer (4370), each coupled to a data acquisition card (9111 DR). A total of 22 features indicative of cracks were extracted from the original signal, including time-domain features (mean, standard deviation, crest factor, RMS, kurtosis, variance), frequency-domain features (power spectral density), time-series model coefficients (AR), and wavelet packet analysis features (RMS, standard deviation, kurtosis, crest factor). A (2x1) self-organizing map neural network was employed to identify the crack and shrinkage effects on the tool state, with the program implemented in MATLAB V.6.5. The results demonstrate that the SOM model can classify cracks with minimal error

This study investigates the effect of considering the third dimension in mass concrete members on their cracking behavior. The investigation includes thermal and structural analyses of mass concrete structures. The thermal analysis determined the actual temperature distribution throughout the mass concrete body due to heat generation from cement hydration and ambient conditions. This was performed using the finite element method to solve the differential equations of heat conduction and convection. The structural analysis adopted the concept of the initial strain problem, and drying shrinkage volume changes were calculated using the procedure suggested by ACI Committee 209. The Willam-Warnke model with five strength parameters was used to model the concrete material, including cracking and crushing behavior. The ANSYS program was employed to perform the analyses. A thick concrete slab of 1.5m in thickness and 10m in length was analyzed for different widths to produce different aspect ratios. The results show an increase in cracking tendency as the aspect ratio increases due to the effect of transverse base restraint

This study investigates the competitive adsorption of furfural and phenolic compounds (parachlorophenol and phenol) onto activated carbon in a fixed bed column. A mathematical model was developed to describe the mass transfer kinetics, considering factors such as competitive adsorption equilibrium constant, axial dispersion, external mass transfer, and intraparticle diffusion resistance. Experiments were conducted to remove these compounds from an aqueous solution, and the equilibrium data and intraparticle diffusion coefficients were obtained. The results show that the mathematical model, which includes external mass transfer and pore diffusion using nonlinear isotherms, provides a good description of the adsorption process for furfural and phenolic compounds in the fixed bed adsorber

This study presents an efficient numerical model to simulate the thermal behavior of the rolling process. The model employs an Eulerian formulation to minimize the number of grid points required. It can calculate the temperature distribution, heat penetration depth, convection heat transfer coefficient of cooling, flow of metal through the roll gap, and heat generation by plastic deformation and friction. The roll is assumed to rotate at a constant speed, and temperature variations are assumed to be cyclically steady state and localized with a very thin layer near the surface. The Conventional Finite Difference (CFDM) method based on cylindrical coordinates was used to model the roll, while a Generalized Finite Difference Method (GFDM) with a non-orthogonal mesh was employed in the deformed strip region and the roll-strip interface area. An upwind differencing scheme was selected to overcome numerical instability due to high velocity (high Peclet number) involved in the rolling process. The equations of the strip and roll are coupled together and solved simultaneously. Both cold and hot rolling heat transfer behaviors, velocity distribution, and heat generation by deformation and friction under typical rolling conditions were presented to demonstrate the feasibility and capability of the developed numerical model

This paper presents an analytical approach to studying the free vibration of thin prolate spheroidal shells under axisymmetric conditions. The equations of motion for the shell are derived using the Donnell-Mushtari shell theory, which considers the effects of rotary inertia and transverse shear deformation. The study explores the influence of the shell\'s geometric parameters, boundary conditions, and material properties on its natural frequencies. Numerical results are provided for various shell configurations, and comparisons are made with existing analytical and experimental data to validate the proposed model

Cathodicprotection is a corrosion-prevention technique which uses the electrochemical properties of metals to insure that the structure to be protected becomes the cathode of an electrolytic cell.Laboratory evaluation was conducted on zinc electrode as anode material that used for sacrificial anode cathodic protection (SACP)of carbon steel.Rate of zinc consumption duringcathodicprotection of carbon steel pipeline carrying seawater (4 % w/v NaCl solution) were measured by the loss in weight technique.Variables studied were seawater temperature (0-45oC), flow rate (5-900 lit/h), pH (2-12) and duration time (1-4 h). It was found that the rate of zinc consumption increases with increasing seawater temperature, flow rate and duration time and decreases with pH increase. Under the mentioned operating conditions, the rate of zinc consumption during cathodic protection of steel ranged from 5.65×10-3to 98.9×10-3g/cm2.day.For the system under investigation, the cell responsible for cathodic protection is Zn/NaCl/Fe

Distilled water flowthrougha virgin hollow fibremembrane, HFMis considered as steady nonuniform since the fibre’swall hydraulic conductivity coefficient is kept constant along the fibre and unchanged during the operation. Under these conditions, two well known lawswereused to mathematicallysimulate the hydraulicflow throughthe HFM. These two lawsare: the Darcy’s Law, to simulate the flow thought the fibre wall, and the Hagen-Poiseuille’s Law, to simulate the laminar flowthrough the fibre channel. Laboratory measurements were carried out to provide necessary data for the calibration and verification of the mathematical model that was developed based on the Darcy’sand Poiseuille’slaws.A good agreement was obtainedbetween the measured and predictedflowratevaluesunder the same conditions.The developed Mathematical model can be used as a tool to investigate the hydraulic performance of commercial HFMmodules.A comparison was made between two commercially available of HFM modulesof the same material but differ in the fibre sizes ;it was found that there is a difference between its performance and the efficiency of the operation energy

This paper presents the results of experimental investigation carried out on concretemodel piles to studythebehaviour of defective piles. This was achievedby employing non-destructive tests using ultrasonic waves. It was found that the reduction in pile stiffness factor is found to be about (26%) when the defect ratio increased from (5%) to (15%).The modulus of elasticity reduction factor as well as the dynamic modulus of elasticity reduction factor increase with the defect ratio

In this paper a theoretical analysis of South Baghdad and Dura power plant is carried out according to second law of thermodynamic depending on entropy (irreversibility coefficient or lost work)method instead of exergy (availability) method. In the used entropy method. The power plant is divided into main blocks ( boiler, turbine, condenser, and feed water heater and pumps ). The irreversibility losses and coefficient for each block are calculated and then the overall irreversibility and thermal efficiency of the plant are calculated. The results of this work are compared with previous results, that depending on exergy method. The comparison of results show that both methods give approximately the same results since both of them rely the 2ndlaw of thermodynamic. Entropy method is simple and intellectually and intuitively satisfying and giving direct relationship between components losses of power plant and its overall efficiency

This Paper aims an identifying the tests of mosaic tiles and incorporated it into management systems, to assist, authors of system that has mosaic tiles is technically accepted (accept lie). This paper presents the important tests taken from the British specifications adding to it other tests which might be necessary to complement the test of the tile that has been technically accepted. The results that were depended on were numbers which might be nearer to reality respecting the used tiles whose results were taken from: 1-The tests that were performed in the lab of testing constructional material/College of Engineering/ University of Baghdad. 2-The test that were performed in the National Center of Constructional Labs. 3-Depending on previous Researches in this field. According to the information, the results of the test and the number of the used tiles in Iraq were established. Then the theoretical information of the research and the lab's result were taken and a management system was made for an information basis of one of the expert systems. Through inputting data by the user of the program to this system, the range of fitness of using the tile could be known

This research explores how the geometry of domes (size, shape, etc.) affects the acoustic performance in mosques. By analyzing sound reflection diagrams, the study provides insights into how different dome formations influence the acoustics within these religious structures. The findings offer a primary vision of the dome's capability in handling sound, which is crucial for designing mosques with optimal acoustic performance

n this paper, soil – pore fluid behavior of a silo under an earthquake loading is investigated. To predict the response of the silo with the soil surrounding it, ‘the linear-elastic constitutive model’ is adopted with soil properties; shear modulus and damping ratio; are strains and cycle independent. A computer program using dynamic stiffness matrix analyses (DSMA) for predicting and analyzing the model was established using FORTRAN coding. The program is based on geophysical values (such as primary velocity (vp), shear velocity (vs), modulus of elasticity (E), mass density (), shear modulus (G),....etc). The values were obtained from field test results for the soil under a silo located in Kirkuk, Iraq. To check and compare the obtained results, the computer program (MSC/NASTRAN) is used also for predicting and analyzing the same problem. This second program uses input values such as shear modulus (G), modulus of elasticity (E), mass density () and damping ratio () obtained from conventional laboratory tests. From the two aforementioned analyses, comparisons between the results of the relevant two programs aremade. Though program “MSC/NASTRAN” visualizes a realistic behavior of the silo under dynamic loading, due to full response results are expressed for each node, the dynamic stiffness matrix analyses program (DSMA) gives only the maximum value for the horizontal and vertical displacements at that node. Despite of that, program DSMA relies on realistic values of geophysical tests obtained from the field directly. As a conclusion from this study, the soil-structure interaction zone for the silo at Kirkuk under investigation using both analyses show excellent agreement between the results. The agreement in this study turns out to be more than 95% close between the two algorithms. The easiness through which geophysical field tests areconducted, the simplicity of carrying out the required calculations and the reliability of the results makes the dynamic stiffness matrix analysis method (DSMA) highly recommended. It can give an excellent directive about the response of structures resting on soils and subjected to dynamic loads

Gypseous Soils are distributed in many regions in the world including Iraq, which cover about (31.7%) of the surface area of the country. Existence of these soils, some times with high gypsum content, caused difficult problems to the buildings and strategic projects due to dissolution and leaching of the gypsum slates by the action of water flow through the soil mass. In this study the effect of treatment with Dihydrate Calcium Chloride (CaCl2.2H2O) as water solution on compaction, compressibility, leaching, permeability and shear strength characteristics of Gypseous soil is investigated. It is found that the maximum dry unit weight increases while optimum moisture content decreases with the increase in the concentration of calcium chloride in the molding water. It is concluded that the engineering properties of the samples are highly improved when the samples are soaked in calcium chloride solution at (20%) concentration. Where, considerable reduction is observed in compressibility, collapsibility, coefficient of permeability, percentage of dissolved gypsum and leaching strain. Also, the treatment minimizes the reduction in cohesion component (c) upon soaking in water and slightly decreases the angle of internal friction (φ). Analysis of the tests results showed that the using of calcium chloride solution in improvement the gypseous soil is more efficient than using it in any other form (powder)

The concept of capacity and level of service are the control points of the analysis of intersections and must be fully considered to evaluate the overall operation of the intersections. The objectives of the present study include the analysis, evaluation and improvement of the operation for AL-Motanabi square in Kut city and to present a best proposal to enhance the performance from the capacity point of view. To achieve these objectives, the estimated distribution of the traffic data in different direction that required for the traffic and geometrical analysis were gathered manually, while SIDRA traffic program is used for the requirements of traffic analysis process. It has been concluded that, two layer flyover is the best proposal to improve the operation ability of AL-Motanabi square

Gypseous soils can be found in arid and semi arid region. In civil engineering it can be defined that a soil is a gypseous soil when it has gypsum content enough to change the properties of this soil. Collapsibility of these soils was found to be of major importance. The collapsibility of the soil can be estimated from the term "Collapse Potential (CP)" which can be obtained from two types of tests performed in the oedometer device; (1) Single Collapse Test (SCT) and (2) Double Oedometer Test (DOT). In this study, an analysis of the results obtained by 7 researchers in Iraq was performed. The data collected included basic properties for each sample in addition to the results of the two collapsibility tests. A total of 50 samples were analyzed and it was noticed that 33 % of the investigated soils have a CP less than 1% which are considered as "No Trouble" soils and about 60% have a CP ranging between 1 and 5 which are considered as "moderate trouble" soils. The factors affecting collapsibility were studied and it appeared that the initial water content, void ratio and total unit weight are the major factors while the gypsum content and plasticity index seem to have lesser effect. Three proposed equations are introduced to estimate CP at 200 kPa as obtained from (SCT) from other parameters. These equations are: (1) CP from (DOT) (2) CP from different soaking pressures and (3) CP from basic soil properties (initial water content, void ratio and gypsum content). These equations have a regression (R-squared) ranging between 0.7 and 0.85

Active control strategy had been used for controlling the vibration response, with considering the simplification in the design and keep away from complexity and high cost in order to extend the actual application of the active control systems. The control program is responsible for identifying the acquired data and make comparisons and decisions required for increase or decrease the actuator stiffness, by instructing the control signal to open the inlet or the exhaust valve respectively. The PC sound card has been used as a Data Acquisition Card. The proposed control strategy had been simulated and tested to control the vibration response of a single degree of freedom spring-mass-damper system excited harmonically at a fixed frequency and with variations of different system parameters (mass, damping constant, and excitation force). Two testing cases are used to investigate the ability of using the proposed actuator and the control strategy in the vibration control field.

A theoretical study of a three-dimensional natural convection heat transfer from an isothermal horizontal square plate, with upper and lower heated surfaces is present. The transient Navier–Stokes and energy equations were solved by using finite deference method (F.D.M). The complete Navier–Stokes equations are transformed and expressed in terms of vorticity–vector potential and solved using an Alternating Direction Implicit (ADI) method for the parabolic portion of the problem, and Successive Over–Relaxation (SOR) method for the elliptic portion .A computer program in (FORTRAN 77) was built to carry out the solution. The numerical results were obtained for laminar flow range of Grashof number up to (105) in up ward–facing and downward–facing with Prandtl number of (0.72). The results of local Nusselt number have maximum values at the outer edge of plate for two cases upward and downward facing heating. The comparison of the results of average Nusselt number with numerical data for downward facing and experimental data for upward facing shows acceptable agreement. It may be noted that the present data are generally different with experimental data, since the available data are extrapolated to high Grashof number. Thus the deviation may be large with present data

A thermal layout modeling and optimization routine for a Printed Circuit Board (PCB) has been made in the present work. The thermal model includes the modeling of electronic components based on thermalresistances and the PCB as a flat plate with multiple heat sources. Isothermal and Isoflux natural convection heat transfer for horizontal and vertical PCB thermal modeling. The numerical solution method for the 2-dimensional thermal model is the superposition method for the adiabatic PCB edges. The optimization meshing model was constructed based on the Complex Method. The numerical Complex Method has been improved to a new optimization method named as "Dual Complex Method", which minimize the objective function to give the optimal step sizes in X and Y -directions. The optimization thermal layout model was constructed to accommodate the numerical SUMT mathematical optimization method. Optimization results show that in free convection, and for the optimum total heat loss objective function, the larger dimension of the PCB must be oriented horizontally rather than vertically, and the electronic components or sub-assemblies of large power should be placed near the top of the PCB. In the case of horizontal upset-down in natural convection, the components of large power must be placed nearthe center of the PCB

This paper proposes a self organizing fuzzy controller as an enhancement level of the fuzzy controller. The adjustment mechanism provides explicit adaptation to tune and update the position of the output membership functions of the fuzzy controller. Simulation results show that this controller is capable of controlling a non-linear time varying system so that the performance of the system improves so as to reach the desired state in a less number of samples

his paper brings together random field generation and finite element technique to model steady state seepage through two dimensional soil domain in which the hydraulic conductivity is randomly distributed in space. The analysis treats the hydraulic conductivity as a spatially random property with specified mean, variance and spatial correlation length. The results of the combined model used in an optimization procedure to obtain the optimum dimension of the hydraulic structure seepage control techniques

In the present study, a general nonlinear one-dimensional finite element beam model is developed for the analysis of composite beams. The proposed model is based on the partial interaction theory of composite beams where the flexibility of shear connectors is allowed. By using a layered approach for the composite beam cross-section and including the material nonlinear behavior of concrete, steel, shear connector and reinforcing steel, the proposed method of analysis is capable of predicting the response of composite beams throughout the elastic, inelastic and ultimate load ranges in one complete analysis. Numerical case studies are presented to demonstrate the validity and applicability of the present method. The results are compared with experimental and analytical or numerical results obtained by other investigators. Also the results are compared with ANSYS package results. The maximum differences in deflection and slip for the examples considered are 12% and 14% respectively when compared with ANSYS and 5% and 11% when compared with experimental work. Accordingly, the proposed nonlinear finite element model represents an efficient and simple tool for the full range analysis of composite beams

A study has been done to analyze the total production system by developing a computer model. Every component of the production system has been programmed individually and then linked in the composite production system computer program. These components are; reservoir component, vertical component, surface choke component and finally horizontal component. Each of the previous components are developed using various equations or models to determine the pressure loss thorough that component. In the current study the Wiggins method has been used to calculate the IPR curves. The vertical and horizontal components are developed using the unified mechanistic model of Gomez. Lage mechanistic model has been used to calculate the pressure losses through annulus. Perkins mechanistic model is used to calculate the pressure loss through surface chokes. A filed example problem is presented to analyze the production system. This example has been used to determine the optimum system design which maximizes production rate for a set of condition

Al-Saidiya PN pumping station raw sewage discharges forms the major pollution source to Tigris river between Al-Jadirriya and Al-Dora bridges, its main importance comes from its location upstream to Al-Dora water treatment plant. In an attempt to evaluate the environmental effects on water quality within the river reach under study, special emphasis was put on evaluating the environmental impact of Al-Saidiya (PN) pumping station wastewater discharges on downstream intakes of water supply, using parameters Oil & Grease, DO, BOD and Coliform & Feacal coliform, in addition to SO4, Cl & EC distributions in three dimensions. It was found that most pollutants concentrations at Al-Dora WTP range within the permissible level for Iraqi raw waters; with the exceptions of Coliform and Feacal Coliform that are highly above the limits; SO4 and BOD showed some high values. Concentrations of pollutants NH3, SO4, BOD, Coliform and Feacal Coliform showed higher values at Al-Dora WTP site compared to Al-Qadissiya and Al-Rasheed WTPs sites. Oil & Grease high concentrations measured at Al-Saidiya pumping station showed that it should not be allowed to discharge directly to the river. Another importance of this location comes from the river hydraulic characteristics represented by the sharp U-shape bend that enhances the transversal mixing process, and hence facilitates the pollutants distribution, through the secondary currents and spiral flow

The effect of longitudinal vibration on the laminar forced convection heat transfer in ahorizontal tube was studied in the present work. The flow investigated is an internal, laminar, incompressible, developing, steady and oscillatory flow. The vibration vector was parallel to the fluid flow direction. The boundary layer was studied in the entrance region for Prandtl numbers greater than one and the hydrodynamic boundary layer grows faster than thermal boundary layer. The governing equations which used were momentum equation in the axial direction, continuity and energy equation. The finite difference technique was introduced to transform the partial differential equations into algebraic equations and the later equations were solved using the upwind scheme. The vibrational Reynolds number used as indication to the vibration and vibrational velocity which is used as boundary condition. The effect of vibration on laminar forced convection heat transfer is to increase the local and average Nusselt number when the vibrational Reynolds number increases; therefore, heat transfer coefficient increases too. Correlations for local Nusselt number with vibration concluded for constant wall temperature and constant heat flux

Conformal projection is one of the most important aspects that geodesy dealing with. The determination of the scale factors in the meridian, the parallel and projected geodesic directions are the final result of the conformal projection. Methods for determining the scale factors in the meridian and the parallel directions have a quite sufficient accuracy. While methods for determining the projected geodesic have different accuracy and computation complicity. This research adopts a modified method for computing the exact value of scale factor in geodesic direction. In this method the scale factor is obtained by determining the true and projected distances of the geodetic line. In the traditional methods for determining the projected distance it is usual to use the 1/3 Simpson's rule in the computations while the modified method the 3/8 Simpson's rule is used. Computations and mathematical tests were carried out to obtain the scale factors using the traditional methods and comparison was made with modified method. By applying the developed method and the traditional methods to calculate the scale factor, it was found that the modified method is more accurate and the projected distances can be obtained exactly