Print ISSN: 1813-162X

Online ISSN: 2312-7589

Volume 19, Issue 4

Volume 19, Issue 4, Autumn 2012, Page 1-84

Numerical Study of Stress Concentration in a Tensioned Plate

Arz Yahya Rzayyig; Ahmed N.Uwayed; Dr.Riyah N.Kiter

Tikrit Journal of Engineering Sciences, Volume 19, Issue 4, Pages 1-13

A numerical study using (FEM) has been carried out to investigate the effect of some parameters on the stress concentration factor in a plate, having different types of cutout and subjected to uniaxial tension. These parameters include the location of cutout, orientation of cutout with respect to the axis of loading, radius of bluntness of cutout and the thickness of the plate. Maximum values of stress concentration factor (SCF) were found in cases of: 1. the cutout is in the center of the plate, 2. the angle of a corner of cutout is bisected by an axis perpendicular to the loading axis, 3. the corners of cutout are sharp (zero radius), and 4.the plate is very thin.

An FPGA Implementation of Secured Steganography Communication System

Sana Sami Mohmmad; Dr. Ahlam Fadhil Mahmood; Nada Abdul Kanai

Tikrit Journal of Engineering Sciences, Volume 19, Issue 4, Pages 14-23

Steganography is the idea of hiding secret message in multimedia cover which will be transmitted through the Internet. The cover carriers can be image, video, sound or text data. This paper presents an implementation of color image steganographic system on Field Programmable Gate Array and the information hiding/extracting techniques in various images. The proposed algorithm is based on merge between the idea from the random pixel manipulation methods and the Least Significant Bit (LSB) matching of Steganography embedding and extracting method.
In a proposed steganography hardware approach, Linear Feedback Shift Register (LFSR) method has been used in stego architecture to hide the information in the image. The LFSRs are utilized in this approach as address generators. Different LFSR arrangements using different connection unit have been implemented at the hardware level for hiding/extracting the secret data. Multilayer embedding is implemented in parallel manner with a three-stage pipeline on FPGA.
This work showed attractive results especially in the high throughputs, better stego-image quality, requires little calculation and less utilization of FPGA area. The imperceptibility of the technique combined with high payload, robustness of embedded data and accurate data retrieval renders the proposed Steganography system is suitable for covert communication and secures data transmission applications.

Productivity Amelioration of Solar Water Distillator Linked with Salt Gradient Pond

Miqdam Tariq Chaichan; Khalil Ibraheem Abaas

Tikrit Journal of Engineering Sciences, Volume 19, Issue 4, Pages 24-34

There is a great need for fresh water in many developing countries. Water sources from, e.g., lakes; rivers and groundwater are often brackish or contain harmful bacteria and should therefore not be used for drinking or irrigation.
In this work a simple solar double sloped basin type still was connected to a solar salt gradient pond. The salinity-gradient solar pond is constructed in such a manner that the convective circulation in the pond is prohibited by making the bottom water much denser than the surface water. In doing so, the solar radiation absorbed in the deep water can be stored; the hot water from the salt pond was used to heat salt water in the stiller, at daylight and night.
The tests were conducted in September and October in autumn season in Baghdad city-Iraq in 2009. The results show development in stiller productivity at daylight and larger productivity increase at night. The stiller productivity increased also with cooling the glass cover from the still outside.

The Effect of Water Absorption on the Creep Behavior for Polymer Composite Materials

Zakariya I. Mohammed; Dr. Samira K. Radhi

Tikrit Journal of Engineering Sciences, Volume 19, Issue 4, Pages 35-53

In this investigation, a low cost, mechanically operated creep testing machine capable of determining the deformation property of material is developed for providing an economical means of performing standard creep experiments. Creep tests are performed to study the nonlinear viscoelastic behavior of epoxy resin and {unidirectional (θ=0o) and woven fabric (θ=0o, 90o)) E-glass/epoxy composite materials under various environmental effects at room temperature and different values of applied stresses. Tested specimens are immersed in three different solutions {acidic water (HCL), PH=5), (distilled water (H2O), PH=7}, and {Alkaline water (NaOH), PH=10}. The experimental creep data can be fitted with general power time function. This function is modified where the effect of gained moisture content, applied stress and aged time on the creep strain are suggested as variables in the creep strain equation. Results show that the creep strain increased with increasing the (pH) level and increased more with increasing the values of the applied stress. Also, the results show that the alkaline water “NaOH solution” is more effective than other solutions on the composite viscoelastic behavior. The concluded degradation rates are 36%, 57% and 62.633% for epoxy, woven fabric composite (Mat) (θ= 0o,90o), and unidirectional composite (θ= 0o), respectively. The developed equation gives an appropriate criterion for describing long time creep strain.

Behavior of the Discharge Coefficient for the Overflow Characteristics of Oblique Circular Weirs

Emad Abdul Gabbar Al Babely

Tikrit Journal of Engineering Sciences, Volume 19, Issue 4, Pages 54-63

This paper presents an experimental study and analysis for effect of the geometrical characteristics, of the oblique cylindrical weir on discharge coefficient, wherefrom three sizes used for the weir and two angles for the deviation.
From the results, it was found that the coefficient of discharge is affected by geometrical characteristics represented by radius of the weir and the angle of inclination with the wall of the channel. It was noticed that the increase in the radius of the weir lead to a low discharge coefficient of the cylindrical weir. And found that discharge coefficient of the oblique weir is higher than the discharge coefficient of the normal weir. And the value of discharge coefficient is directly proportional with the weir inclination.

A Study of ZigBee Network Topologies for Wireless Sensor Network with One Coordinator and Multiple Coordinators

Shayma Wail Nourildean

Tikrit Journal of Engineering Sciences, Volume 19, Issue 4, Pages 64-80

Wireless Sensor Networks have become a cheap and viable solution for a variety of applications, including monitoring of critical infrastructure (water supplies, power grids, traffic networks, agriculture, telecommunications systems etc.), wildlife habitat monitoring, industrial quality control, disaster recovery situations, military applications and much more. The ZigBee network model is more suitable for battery capacity, bandwidth and computing power’s limitations of WSN. In the present investigation, the modeled system was simulated using OPNET Modeler v14 to obtain the results in order to study the performance of the system in terms of tree routing, mesh routing, multiple coordinator system and if one of the coordinators was failed. The results showed that tree routing was more suitable for WSN than the mesh routing and mobility of end device was better in multiple coordinator system.

Generation of Domestic Solid Waste in Tikrit City and The Effects of Family Size and Incomes Level on the Rate of Generation

Tikrit Journal of Engineering Sciences, Volume 19, Issue 4, Pages 1-11

تم في هذا البحث جمع وتحليل (2800) عينة من أربعة أحياء سكنية مختلفة في تكريت على مدار فصول السنة لتغطية التغيرات الفصلية في معدل إنتاج النفايات الصلبة المنزلية. وقد بلغ معدل إنتاج النفايات الصلبة المنزلية (0.460) كغم/شخص/يوم. كما بينت النتائج أن أكثر فصول السنة إنتاجا للنفايات الصلبة المنزلية هو فصل الصيف إذ بلغ معدل الإنتاج فيه (0.487) كغم/شخص/يوم، في حين أن أدنى معدل إنتاج كان (0.422) كغم/شخص/يوم شتاءً. في حين بينت النتائج أن أعلى معدل إنتاج للنفايات الصلبة المنزلية سجل خلال يومي الجمعة والسبت وبمعدل (0.629) و (0.557) كغم/شخص/يوم على التوالي. كما أظهرت النتائج تأثير الطابع الريفي لمنطقة العلم في خفض معدل إنتاج النفايات الصلبة المنزلية إذ بلغ معدل الإنتاج للأحياء الأربعة المدروسة (0.460) كغم/شخص/يوم، أما للأحياء المدروسة ماعدا منطقة العلم فقد بلغ معدل الإنتاج (0.478) كغم/شخص/يوم.وقد تم اعتماد طريقة التحليل الإحصائي باستخدام برنامج SPSS لدراسة تأثير كل من حجم الأسرة ومستوى الدخل لها على معدل الإنتاج في المدينة. حيث أظهرت النتائج أن لحجم الأسرة تأثيراً عكسياً على معدل إنتاج الفرد الواحد من النفايات الصلبة المنزلية، كما أن أدنى معدل أنتاج كان للأسر ذات الدخل الجيد.

Improvement of Production Quality by using Six Sigma Technique:

Tikrit Journal of Engineering Sciences, Volume 19, Issue 4, Pages 12-23

As a result of lack of conformity of the outer diameter of the filling piston of plastic syringe to the specifications set out in the design map and the increased demand for its products from the Medical syringes factory – Babylon. The research conducts the necessary investigations and analysis of the production process as most of the units rejected by fact that the outer diameter of the filling piston is smaller than the minimum specification and units returned to work due to the fact that the outer diameter larger than the upper limit of the specification.
The research aims firstly to examine the outer diameter of the filling piston through the use of the control chart of the variables represented by the average , and its impact on the production process capability because the increase in diameter specification leads to an increase in the pressure imposed on the lining of the cylinder, causing difficulty in piston movement and a decrease in diameter specification which leads to loose the process capability to prevent leakage of fluid, causing air to enter as well as to speed the movement of the piston, which negatively affects human life in both cases. Secondly, study the possibility of improving the production process capability by using advanced levels of the sigma.
The results showed that the production process in the case of a disciplined and follows a normal distribution, the pointer of the production process capability is equal to (0.55) and the factory works within the level of Sigma equal to (1.65). The proportion of a damaged product is (15.8 %) and rework (0.99 %).
In order to reduce the proportion of damaged product, this paper introduces a quality plan depending on ( ±0.025) as tolerance limits instead of ( ±0.05) to increase sigma level by 202%.

Effect of the Presence of Semi-circular Cylinders on Heat Transfer From Heat Sources Placed in Two Dimensional Channel

Tikrit Journal of Engineering Sciences, Volume 19, Issue 4, Pages 24-45

The effect of a semi-circular cylinders in a two dimensional channel on heat transfer by forced convection from two heat sources with a constant temperature has been studied numerically. Each channel contains two heat sources; one on the upper surface of the channel and the other on the lower surface of the channel. There is semi-circular cylinder under the source in upper surface and there is semi-circular cylinder above the source in lower surface. The location of the second heat source with its semi-cylinder has been changed and keeps the first source with its semi- cylinder at the same location. The flow and temperature field are studied numerically with different values of Reynolds numbers and for different spacing between the centers of the semi-cylinders. The laminar flow field is analyzed numerically by solving the steady forms of the two-dimensional incompressible Navier- Stokes and energy equations. The Cartesian velocity components and pressure on a collocated (non-staggered) grid are used as dependent variables in the momentum equations, which discretized by finite volume method, body fitted coordinates are used to represent the complex channel geometry accurately, and grid generation technique based on elliptic partial differential equations is employed. SIMPLE algorithm is used to adjust the velocity field to satisfy the conservation of mass. The range of Reynolds number is (Re= 100 – 800) and the range of the spacing between the semi-cylinders is(1-4) and the Prandtl number is 0.7.
The results showed that increasing the spacing between the semi-cylinders increases the average of Nusselt number of the first heat source for all Reynolds numbers. As well as the results show that the best case among the cases studied to enhance the heat transfer is when the second heat source and its semi-cylinder located on at the distance (S=1.5) from the first half of the cylinder and the Reynolds number is greater than (Re ≥ 400) because of the separation behind of the first semi-cylinder where it works to reduce the area of section flow, and this is leading to increase the speed and thus increases the rate of heat transfer. A comparison of numerical results agrees well with published results.

The Effect of use the Silica Sand

Tikrit Journal of Engineering Sciences, Volume 19, Issue 4, Pages 48-62

This research includes study the effects of use the silica sand at different rates and comparison some characteristics with other concrete mixture contains ordinary sand to investigate the effect on some mechanical properties of concrete such as compressive strength, density absorption and flexural strength after (3, 7, 14 and 28) days for four mixtures. , the ordinary sand was replaced by the (Silica Sand) at different rates ( 25%, 50%, 75%, 100%). Sodium Silicate solution at percentage of cement ratio(water to cement ratio is decreased on same ratio) added to the Ideal silica sand mixture to study the effect of addition of some additives on concrete. The study showed that the best results of mixture was when replaced (75%) of the ordinary sand by silica sand , then study some mechanical properties of mixtures such as compressive strength, density absorption and flexural strength after (3, 7, 14 and 28) days .
The study showed the optimum percentage of sodium silicate was (1.75%). The study showed that the best result of Density was (2493Kg/m3) after (28) days, and the increment ratio in Density was (2.95%), and the large value in compressive strength was (85.76 MPa) which was (42.9%) after (28) days. The study showed also that the best results of absorption were (0.77) after (28) days, and the decrement ratio in Absorption was (33.8%). The study showed that the best result of flexural strength was (8.02 MPa) after (28) days, and the maximum increment ratio in Flexural Strength was (150.6%) after (28) days.

Evaluation of Alton Kobry Region Ground Water for Civil Uses

Tikrit Journal of Engineering Sciences, Volume 19, Issue 4, Pages 63-73

This study has been performed at the Alton-Kobry region to indicate the suitability of the ground water which is important source for domestic uses.
The samples taken from (19) wells at different locations and tested at laboratories of north gas company in Nov.-2010.The tests included (electrical conductivity, total dissolved solids, pH-value, concentration of some anions) were all conducted for each sample.
The results revealed that surveyed ground water were free from pollution and almost suitable for domestic use.
Some investigated parameters appeared to be near the recommended limits set by Iraqi standards, while others exceed the recommended values that the chemical treatments are necessary.

Study the Effect Of Magnesium And Zinc Additions On Thermal Properties Of Pure Aluminum

Tikrit Journal of Engineering Sciences, Volume 19, Issue 4, Pages 74-84

This research, a practical study was achieved to demonstrate the effect of adding Magnesium and Zinc elements on the thermal properties of pure Aluminum. These properties are: the quality thermal capacity (Cv), the thermal conductivity coefficient (k), and the thermal diffusion coefficient ( ). Seven metal ingots were manufactured by changing the percentages of adding Magnesium and Zinc on the pure Aluminum, and these ratios were: (5%, 10%, 15%, 20%, 25%, 30%).
The obtained results showed that increasing the percentages of adding Magnesium and Zinc to the pure Aluminum causes a decrease in the ingot density by (10.7%), a decrease in the thermal conductivity coefficient by (8.1%), an increase in the quality thermal capacity by (4.8%), as well as a decrease in the thermal diffusion coefficient by (1.9%). As for Zinc, the density increases by (49.2%), as the density of Zinc (7.13)kg/m3 is higher than the density of Aluminum (2.7) kg/m3, and higher than the density of Magnesium (1.74) kg/m3, as well as decreasing the thermal specifications (Cv, k, ).
During this study, it was found that the best addition is (30% Mg) to the pure Aluminum, which gave the highest thermal properties (Cv, k, ). As for Zinc, its addition to pure Aluminum led to deterioration of the thermal properties during all ratios.