ISSN: 2521-9154

Volume 11, Issue 3

Volume 11, Issue 3, Autumn 2008, Page 342-571


Factors Affecting the Slenderness Limit for RC Columns-The Use of the (ACI-318M-05) Provisions

Ihsan A. S. Al-Sharrbaf

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 342-356

The current ACI code and many other codes permit the moment magnification method for design of slender reinforced concrete (RC) columns. Manually, the design/analysis procedure is tedious, so that the codes state a pre-prediction if the column is slender or not. In other words, before starting design codes provide slenderness limits to be considered to decide whether a column is slender or not.
This work will concentrate on the slender RC column provisions of the latest ACI Code. Using this method some columns are found to be short. In the proposed method of this work, it is found that some of these “short” columns are found to be “long”, thus needing moment magnification. Since column analysis/design represents dealing with one of the most critical parts of RC buildings, this proposed magnification is presented in this work.

Remote Sensing and GIS Techniques for Monitoring Industrial Wastes for Baghdad City

Mohammad Ali Al-Hashimi

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 357-365

The city of Baghdad is located in the central Mesopotamian plain of the Twin Rivers. According to the geological surveys, the whole area is covered by recent sediments of alluvial origin, deposited by successive floods of Tigris and Euphrates rivers, and by wind action. Since Baghdad city is the capital it surrounded by network of industrial areas for different purposes and this, affect the environment. Solid wastes generated from both animal and domestic sources can significantly impair drinking, irrigation, recreational water, other water sources and soil in rural and urban areas therefore it must be monitored and controlled very well to protect the wild life and environment and this represent the goal of research tool used for this purpose is remote sensing and Geographic Information System (GIS) due to their ability of monitoring and analyzing large amount of data. The techniques demonstrated in this research include procedures for developing regional spatial data into a coordinated GIS database, characterizing and identifying wildlife habitat, quantifying and assessing land use change, pollution due to changes in land use and demonstrating the application of these GIS and modeling methods for assessing cumulative environmental effects associated with landuse change.
Geographic Information System (GIS) and remote sensing techniques are used to monitor the environment in Baghdad city especially the industrial waste. Using GIS and remote sensing techniques in the environmental assessment give a quick and low cost. Preliminary investigation can be considered as aiding tools to the traditional and detailed investigation procedures.

Evaluation of Properties of Roller Compacted Concrete

Afrah A. Hamzah

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 366-373

The experimental and analytical behavior of various mixes of roller compacted concrete (RCC) using different materials is presented in this work. This work is divided into two groups of experiments.
In the first group a reference mix was prepared using local materials (cement, sand, aggregate). Mechanical and dynamic properties of reference mix with and without admixtures have been obtained. Also, this series includes a study of the various variables affecting the mechanical and dynamic properties of RCC.
In this work, the effect of cement content, water/cement W/C ratio and type of aggregate on the mechanical properties has been studied. The optimum mixes which have good properties obtained from the first group of study were used in the second group.
In this work, the effect of admixtures and type of admixtures (steel filings, metakaolin, fly ash, lime, rice husk and concrete wastes) on the mechanical properties has been studied.
The analysis of results showed that using steel filings improves the mechanical properties when replacing the sand by steel filings in (5, 10, 15 and 20) % by weight. The ultimate compressive strength at 7 and 28 days is higher by 13.2 and 24.7%, respectively, than the compressive strength using sand only. Partial cement replacement by mineral admixtures like metakaolin with (10, 20 and 30) %, lime with (4, 6, 8, 10, 20 and 30) %, fly ash with (10, 20 and 30) % and rice husk with (4 and 8) % decreases the strength and other properties at early age of 28 days by about 12.02% when using metakaolin by 20% and about 12.5% when using lime by 10 %.

The Effect of Reinforcement Density on The Deflection of Reinforced Soil Retaining Wall

Dhiaadin Bahaadin Noory Zangana

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 374-381

This research involves the effect of both vertical and horizontal spacing, as well as the length of the reinforcing strips, on the structural behavior of a model reinforced soil retaining wall.
The tests were carried out on a small-scale laboratory model, in which uniform graded sand was used as a fill material. It was placed at a high dense state; raining technique was used for this purpose. The sand was reinforced with thin dipped Aluminum strips. The size of these reinforcing strips was chosen sufficient enough to prevent rupture mode of failure. The retaining wall was presented by a plastic transparent sheet. The results showed that the horizontal spacing is more significant parameter on deflection of the wall as compared to the vertical spacing of the reinforcing strips. The critical values of the horizontal and vertical spacing with respect to this research were 20 and 10 cm respectively. A short length of reinforcement proved to cause appreciable deflection of the wall, even under close horizontal and vertical spacing

Reinforcement Design Algorithm For Concrete Shells

Hani M. Fahmi; Nabil M. Ali

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 382-394

The absence of universally accepted solutions in the structural concrete codes for the design of reinforcement in shells gives rise to the problem of calculating the required reinforcement in these structures. The constant development of the computer’s performance and storage capacity combined with the powerful numerical methods reveal the need for a standard procedure to design shells subjected to membrane and flexural forces.
In this paper, the solution for the design of the required reinforcement in concrete shells is presented based on a complete iterative computational algorithm to design shell elements subjected to combined membrane forces and bending moments.
In the design equations, the reinforcement will contribute to tension and the concrete compression struts parallel to the crack direction will contribute to compression. The reinforcement is assumed to have two orthogonal layers placed in the top and bottom surfaces with appropriate covers. Each reinforcement layer has reinforcing bars placed orthogonally. For the concrete compression struts, the stress is assumed to be uniformly distributed in the depth of Whitney’s stress block.
This design algorithm is achieved by developing a design code (DRCSH) based on a complete iterative computational algorithm. This program can be used as a stand-alone version, to determine the load carrying capacity of critical points in reinforced concrete panels, plates and shells; and to verify the design code on the element level, five experimental models are designed. The designed elements give calculated ultimate strengths from 7 to 18% higher than test results values, except one model, which confirms the adequacy of the design algorithm, and the developed design code.

Study the performance of High Voltage Direct Current Transmission using MATLAB

Jameel K. Abed Al-Jashami

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 396-409

Some of the electric networks adjacent countries are linked to either the alternating current lines or to direct current lines, that is really depends upon the geographic distance of the linking points and the amount of the used current. In view of rapid and huge increasing of electric power consumption and to shorten the value of losses inside transferring operation besides the electric system steady. Accordingly and due to all we have mentioned the direct current transmission has been established in high voltage for long distance. These lines can be used when the linking points are far- off, and when the frequency for the two required systems are different. Therefore transformation stations are being used at both ending sides to transfer from alternating to direct current and vice-versa. Also a (HVDC) system can be constructed according to stages in proportion with the voltage development and the load requirement. There is always the need to maintain the transformation voltage at ultimate possible value in order to have a high efficiency operation. In this paper the transmission line was represented by using MATLAB program for two different lengths (300,600) Km & different firing angles then comparison is held between these two lengths according to efficiency & economical view.

Reduced States Multilevel Space Time Coding

Nadia M. Al-Sanie; Muzhir Sh. Al-Ani

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 410-418

There is an increasing demand for higher data rates and higher quality in wireless communications that has motivated the use of multiple antenna elements at both the transmitter and the receiver sides of a wireless link. Space-time coding (STC) deals with the design of good codes of multiple antenna wireless systems.
A new proposed orthogonal code is designed and presented in this paper as an improved design of delay diversity for multilevel space time coding with multiple inputs and multiple outputs. The code is based on using two signals transmitted at different rates in order to remove the problems that appear from different types of fading due to multipath channel and to reduce intersymbol interference (ISI) between the symbols.
The transmitter and the receiver are designed to encode and decode the proposed orthogonal code through the frequency selective and flat fading channels. Time invariant rapidly varying fading channel is included ; that the path gains change for each symbol. The detection is non coherent STC that neither the receiver nor the transmitter knows the channel propagation coefficients. Quasi-static fading channel with coherent STC is also included, that only the receiver has knowledge of the channel through training symbols is available at the beginning of each frame of the receiver. The method gives coding gain, diversity gain as well as the design of the proposed code for three or four transmitting antennas with low complexity.

Stress Analysis of Fiber-reinforced Composite Built-up Beam Using the Unit Cell Method

Luay M. Ali; Ala; a M. Hussain; Haydar A. Hussain

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 419-428

Macro- and microscopic levels of analyses are used to capture the behavior of a built-in beam made of a unidirectional fiber-reinforced polymeric material. Finite element formulation basing on the displacement approach and minimum potential energy principle is carried out in the longitudinal direction of the beam to determine the vertical displacements (deflections) at various sections, stresses and strains. A unit cell method in micromechanical analysis based on the finite element method is used to define the state and distribution of the stresses induced in transverse sections. Hexagonal fiber-matrix packing system is idealized for the problem. The package of ANSYS 5.4 and a Matlab program are used to solve for the macro- and micromechanical analyses. To examine the validity of the presented method, it is applied to analyze a beam made of matrix and fibers with the same elastic properties the results are then compared with those obtained by using a method used for isotropic materials given that properties , the convergence noticed is verifying the validity of the analysis method adopted by the current work.

Analysis of Friction Stir Welds. Part I: Transient Thermal Simulation Using Moving Heat Source

Qasim M. Doos; Muhsin Jabir Jweeg; Sarmad Dhia Ridha

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 429-437

This paper describes the first part of the development of a non-linear finite element simulation of the friction stir welding process; it is concerned with thermal analysis. A transient, three dimensional, non-linear thermal model with moving heat source was developed. Also a steady-state, three dimensional, non-linear fluid-thermal model with stationary heat source was developed. Differences of results for both models were discussed. Results of both models were compared with experimental work. Transient thermal model results appear to be more reliable as compared to the CFD approach

Modeling of Oxidation Kinetics in Air of Steel-T21 Alloy Coated by Simultaneous Germanium-Doped Aluminizing-Silicon zing Process

Abbas Kh.Hussein

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 438-449

This work includes the application of a pack cementation of germanium-doped aluminum and silicon coatings on low alloy steel type-T21 yields a significant improvement in the oxidation. Steel-T21 was coated with germanium-doped aluminzing-siliconizing. Diffusion coating was carried out at 1050 oC for 6 h under an Ar atmosphere by simultaneous germanium-dopded aluminizing-siliconizing process. Cyclic oxidation tests were conducted on the coated steel-T21 alloy in the temperature range oxide 600-800 oC in air for 30 h at 5 h cycle. The results showed that the oxidation kinetics for coated system in air was found to be parabolic .Oxide phases that formed on coated system are SiO2 and Cr2O3..Mthamatical model using MATLAB show that there is multiple linear model for oxidation kinetics.

Finite Element Analysis Using MATLAB of Oxidation Properties in H2O Vapor of Steel-T22 Alloy Coated by Simultaneous Y-Doped Chromizing-Siliconizing Process

Sabah Kh.Hussein; Abbas Kh.Husssein; Kadhim K.Resin

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 450-458

The application of a pack cementation of Y-doped chromium and silicon coatings on low alloy steel type-T22 yields a significant improvement in the oxidation resistance. Steel-T22 was coated with Y-doped chromizing-siliconizing. Diffusion coating was carried out at 1050 oC for 6 h under an Ar atmosphere by simultaneous Y-dopded chromizing-siliconizing process. Cyclic oxidation tests were conducted on the coated steel-T22 alloy in the temperature range 300-500 oC in H2O for 100 h at 5 h cycle. . The oxidation kinetics for coated system in H2O was found to be parabolic .Oxide phases that formed on coated system are SiO2 and Cr2O3. Finite element results show that there is a good agreement between FEM and experiments results.

Optimum Height of Plate Stiffener under Pressure Effect

Mazin Victor Yousif; Nazar Kais M. Naief; Yahya M. Hamad

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 459-468

The economical design of plate loaded by pressure can be obtained by using stiffeners instead of increasing the thickness of plate. The main subject of this work is to obtain the effect of stiffener height on the maximum stress in the plate subjected to pressure load. Different plate-stiffener sets are selected to find the effects of stiffener thickness, plate dimensions and pressure, on the optimum stiffener height. The models under consideration are square plates clamped rigidly from four edges.
Finite Element method is used to analyze 160 different models by using the Finite Element software package ANSYS version 11. Another analysis method based on maximum stress equation is used to analyze 30 models. The graphical comparison of results between two analytical methods is presented by a figure. It is found that the numerical results obtained by Finite Element Analysis converge to theoretical results.
The optimum height of stiffener under above different effects is found. The critical pressure curves for square plate dimension sets are also presented.

Effect of In-Plane Biaxial Compression Force on Penetration Resistance for Steel Plate

Najdat Asker Mahmood; Mohammed Zakaria Salah Salem

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 469-477

The importance of penetration and perforation in to targets in both military and civilian applications has made it the subject of many investigations. But the bulk of these investigations was experimental rather than analytical or numerical because of complexity of the governing equations. Hence most of the existing models are either mathematically rigorous or so simplified that they neglect many important parameters. Moreover, weight and cost are among the most important consideration in the design of perforation resistant systems (containment shields). Therefore, the present investigation has focused on the perforation and penetration of relatively thick metallic targets by rigid cylindro-ogival projectiles. To achieve the experimental part of this work a locally manufactured compression device was built for this purpose where the target plate was subjected to biaxial compression load of about 0.6 of its buckling load. A life 7.62 mm ammunition with steal projectiles have been used to impact the targets at 400 and 600 m/s thus the exit velocity in terms of the impact velocity and the total work done at the target was derived for the case of biaxial compression. Comparison of the experimental and the analytical results showed a good agreement while targets in the state of compression showed about 80% improvement in penetration resistance.

Improvement of Retread Blends Composed of Natural Rubber(Nr) And Polybutadiene Rubber(Br)

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 478-484

Tread of the tire is occasionally dislocated due to sever running on the road. Retreading is necessary in this case, and retread rubber compounds are made from a blend of NR/BR by using several additives like Activator Accelerator such as Zn salts of high molecular fatty acid (LAUREX) & homogenizing agents (Struktol-MS) produced by Uniroyal, Delayed Action Accelerators type Thiazoles and Sulfenamides such as (AMAX & MORFAX) produced by Vanderbilt.. insoluble sulfur, Pine Tar and others.
An infinite number of rubber recipes are possible in blends. The best properties of each components are selected to achieve a blend having a wide spectrum of properties (recommended for retreading compounds) which is superior to that of the individual component and also economically competitive. The effect of using different levels(0.6,0.65,0.85pphr) of accelerators such as (AMAX & MORFAX) are enhancing the phsico-mechanical properties(tensile strength, modulus,shore hardness and abrasion resistance index), and the Activators Accelerator (LAUREX & Struktol-MS) in the rubber compounds are evaluated in such away that LAUREX is more affective in recipe no.3(2.5pphr) than the same level of Struktol-MS, so that it is making use of preparing suitable retreading rubber compound

Effect of NCO/OH on the Mechanical properties of Polyurethane Elastomers

Malek M.Mohammed; Mustafa M. AL-Jarrah; Ahmed A. Abdul Lateef

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 485-493

The present work is concerned with the preparation of polyurethane elastomers.
Polyurethane elastomer was prepared by the bulk polymerization via one-shot method of 4,4'diphenyl methane diisocyanate (MDI) with polypropylene glycol (PPG) and 1,4 butandiol using stannous octeate as a catalyst.
The operating conditions of the polymerization were studied and their affects on the mechanical properties of the prepared elastomer.
100 grams of polypropylene glycol with 0.1 ratio of catalyst was used with 4,4'diphenyl methane diisocyanate to equivalent of polypropylene glycol (NCO/OH) (1.5-
3), and curing temperature of about 110 °C.
Under these conditions, the mechanical properties of polyurethane elastomers were:
The tensile strength (16 MPa).
Hardness, shore A (86).
Elongation % (274).
Modulus of elasticity 100% ( 9 MPa).
Kinetic of the reaction also was studied using adiabatic temperature rise method. The overall order of reaction was 1.5, the activation energy of the reaction was (40 KJ/mole), and frequency coefficient of reaction (4.857 ×104 (mole/g mixture)-0.5 S-1)

Municipal Wastewater Treatment Using Reed Bed Eco-Technology

Mohammed Al-Saad

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 494-500

The treatment of municipal wastewater using engineering constructed Reed Bed wetland system was investigated in this research work at Al-Nahrain University
A reed bed pilot plant, for treating 2m3/day of municipal wastewater has been designed, constructed and is being running for 12 months now. The system is based on the principles of sub-surface flow constructed wetlands. It consists of two beds (two steps), filled with gravel and sand layers as filter media. The first and second bed were designed to give 2 and 5 days retention time respectively and are capable of handling hydraulic surface flow up to 170 l/m2.day. The two beds were planted with Phragnmites communis (common reed).
The general aim of this research work was to start implementing this new technology, for the first time, in Iraq and put the basis for future research work on this promising eco-technology in attempts to overcome the problems facing the wastewater treatment sector in general and the existing conventional treatment system in particular and to find the right solution for healthy environment.
The findings of this research work can be summarized as follow, the improvement of the pollutant removal was proportional to the maturity of reed plants and the results obtained after running the pilot plant for nearly 12 months were, 95% for BOD5, 97% for TSS, 65% for TP, 41% for NO3-N, 39% for NH4-N and with no pathogenic (disease-causing) organisms found in the treated wastewater, were obtained. The results were good and the design is expected to give better results when the reed plants reach their maturity state. During the hot and dry season the evapotranspiration rate was higher than the influent rate and, as set by the reed bed design, a stage was reached where a complete dry out of the system occurred. Better pollutant removal results were obtained during the hot and dry season when high rate of evapotranspiration causes high pollutant concentration inside the reed bed. This finding indicates that high pollutant concentrations are generally advantageous for such treatment system. Moreover, periodically drying the system is the ideal condition for aerobic bacteria to increase in quantity and diversity which resulted in higher removal of organic pollutants.

Object Dimension Inspection Utilizing 3D Laser Scanner

Omar M. Salih; Mohammed Z. Al-Faiz

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 494-500

In this paper, the processes of 3D LASER scanning and dimension inspection were simulated for certain dimensions object. The scanning operation is divided into two major modes, Searching Mode and Scanning Mode. In scanning mode two sub-processes (scanned point validation and plane fitting) are introduced, i.e. to find the plane which contains most of scanned points. The final step is the decision making, which gives a decision about acceptance or rejection of the scanned manufactured object. The proposed algorithm is successfully applied to seven cases. One of them which has the exact dimensions and this case has been accepted. The other six cases, which have different dimensions, have been rejected.

Constant Bit Rate For Video Streaming Over Packet Switching Networks

Hamsa A. Abdullah; Nasser N. Khamiss

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 501-510

This paper proposed a technique of bit-rate control for video streaming over constant bit-rate communication channel, where the MPEG-2, standard variable bit-rate (VBR), is adapted to be used as a constant bit-rate (CBR). The target image quality and output rate of the video encoder is controlled by feedback based on the buffer level. A CBR transport over networks, result is a good performance compared with that of VBR. It introduced simplicity of network monitoring and analysis, where the VBR video streaming over CBR channel can be adapted to avoid the problem of congestion of the network. This paper studies the important issue of adapting VBR-compressed video for transport over a CBR channel. The developed systems are implemented using Matlab (Ver 6.5) under Windows XP operating system.

Investigation of Raman Amplification In Photonic Crystal Fibers

Zahraa M. Ali Kamil; R. S. Fyath

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 511-521

In this paper, Raman amplification characteristics in photonic crystal fibers (PCFs) are investigated in details. Performance comparsion between PCF-based Raman amplifier and other conventional fiber-based counterparts is presented. The simulated results reported here can be used as a guide line to design PCF-based Raman amplifier that outperforms the conventional fiber amplifiers. Raman gain as high as 33 dB can be obtained with a well designed PCF even at low pump power of 300 mW.

The Role of Lubrication Mechanisms in the Knee Synovial Joints

Aseel Mohammed Ali; Albert E. Yousif

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 522-535

Synovial joints form the most important feature of the human body as they represent the centers of the most essential and basic activity in the human beings, which is motion. Starting from the role that are played by the lubrication regimes in effectiveness and maintenance of the joint this study was initiated. It investigates the lubrication systems that are operative in synovial joint. Depending on the loading conditions and sliding velocity during one gate of the walking cycle the profile of the synovial film thickness and the pressure developed in the knee joint when the hydrodynamic and elastohydrodynamic lubrication regimes are operative was determined.
For the hydrodynamic and elastohydrodynamic lubrication analysis a mathematical model obtained by solving the governing equation using numerical methods. Results showed that for the hydrodynamic action the minimum film thickness determined was between (0.365-1.8) µm and the pressure developed ranged between (20.6-860.449) kN/m2. While for elastohydrodynamic action the minimum film thickness ranged from (2.5-3.57) µm and the developed pressure ranged between (97.68-146.5) kN/m2. Finally, it was shown that in specific conditions hydrodynamic and elastohydrodynamic lubrication mechanisms gave a good explanation to how the joint functions

Study the Effect of Illumination Time Parameter of Diode Laser on Wound Healing Process

Saif Dawood Salman; Munqith S. Dawood

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 536-543

In this study we introduce a solution for wound healing controlling therapy by using a monochromatic pulse diode laser light 650 nm, 50% duty cycle and 1 MHz.
Many studies proved last years a positive effect of diode laser light application in wound healing process.
In this paper we study the effect of time illumination parameter on healing process. For this kind of therapy, a 650 nm diode laser used. Its original electronic circuit drive was improved to give pulsed output laser of 50% duty cycle, 1 MHz.
Twenty male mice, three months old were usd in this study (photo-biostimulation). The wound was made on bilateral back sides of each mouse, two sessions of illumination carried everyday for 12 and 18 minutes during 15 days time. This study was compared with our previous study set for 5 minutes for one session therapy in 1st and 2nd day of healing process.

An Investigation Behavior Into Dental Biomechanical Analysis

Amal Ibrahim; Sadiq Jafer Abbass

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 544-551

The aim of the study is to evaluate the Von Mises stress distribution of different human teeth model. Three-dimensional model of the maxillary central incisor, mandibular first molar and mandibular central incisor were constructed using Auto CAD (Auto CAD 2007) software and then imported to ANSYS software (ANSYS V.10) to get finite element model of each teeth. A loading simulating the 200N force was applied vertically and with different inclination to the crowns. Then same loading was applied vertically but the load was distributed along the incisal area for the incisors and at occlusal margin for the molar. Finally the crown was considered as porcelain material and the vertical load was distributed along each tooth and the Von Mises stresses were calculated. The results showed that the increase in the loading angle from 0°, 26° to 45° resulted in an increase in tooth Von Mises stress which means increase the probability of tooth failure. When the load distributed along wide region the ability of model to fail for the same loading will be decreased. Also when the crown consider as porcelain material there will be increasing Von Mises stress compare with the enamel crown for the same load region and load value

Policies of Architectural Conservation in Ancient PlacesCase study: Historical Citadel of Erbil

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 564-571

The research aims to determine the suitable policy to preserve the historical Citadel of Erbil basis of the data into three stages through which the morphological (Citadel planning and its construction, urban fabric, and urban land use) trying to answer the following questions: - To what extent the Citadel can be consider as a Frey (eroded)?
- To what extent can maintain the existing buildings within the parameters of acceptable planning? - How can we Revival the Citadel within the modern urban fabric of the City that is not at the expense of the Architectural heritage of the Castle? Using the Analytical - Descriptive methodology, reached several Conclusions and Recommendations to avoid errors committed by the former in the Revival of this site and other Historical sites in Iraq

Utility of Non Destructive Tests to Assess the Compressive Strength of High Performance Concrete

Sura F. Al-Khafaji; Waleed A. Al-Qaisi; Shakir A. Al-Mishhadani

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 11, Issue 3, Pages 552-559

In this study, high performance concrete mixes were produced by using high range water reducing agent(Glenium 51) and also by using 10% silica fume or 10% high reactivity metakaolin as a partial replacement by weight of cement. Three cement contents (350, 450, and 550) kg/m3 were used through this study. A total of 330 (100 mm) cubes, 66 (150×300 mm) cylinders, and 132 (100×100×400 mm) prisms were cast and cured to the required age of test. Compressive strength, rebound number, ultrasonic pulse velocity and dynamic modulus of elasticity were investigated for all mixes at 7, 28, 90, and 120 days age. Results of the destructive test of compressive strength and non–destructive tests (hammer, ultrasonic pulse velocity, and dynamic modulus) are statistically analyzed by using SPSS Ver.15 software to study the possibility of assessing the compressive strength of high performance concrete by using non–destructive tests. Simple and multiple linear regression analysis of the obtained results leads to the proposed statistical models for evaluating the compressive strength by using one or two or three of the above non–destructive tests. Analysis of variance (ANOVA) and t–test was also used to investigate the adequacy of the statistical models. The statistical models were subjected to adequacy checks at a selected level of significance of 5%.