ISSN: 2521-9154

Volume 12, Issue 2

Volume 12, Issue 2, Autumn 2009, Page 102-194


IPI Removing by Using Reference Sign/N-ary Orthogonal Coded/Balanced TR-UWB Receiver for WPAN Based on Hadamard Matrix

Saleh M. Al-Qaraawy

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 12, Issue 2, Pages 102-107

IR UWB system has been proposed as a promising physical layer candidate for indoor wireless communications, because it offers very fine time resolution and multipath resolvability. Inter pulse interference (IPI) is one important challenge related to the transmit reference (TR) IR UWB receiver. In this paper, an attempt to completely remove the IPI problem in TR with increasing the data rate. This is achieved by using orthogonal codes generated from modified version of Hadamard matrix via the application of the reference sign technique, i.e., by modulating the reference pulse besides the already data modulated.

The Effect of Area Reduction of Forward Die on the Combined Forward- Backward Extrusion Process

Ali Hassan Saleh; Muhsin Jabur Jweeg; Jamal Hussien Muhamed

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 12, Issue 2, Pages 108-121

The effect of reduction area for flat and conical dies in forward-backward extrusion process was investigated experimentally using flat punches with three reduction areas (0.305,0.444,0.605), 0.444 with cone angles (60o,90o,120o) and polygonal punches (hexagonal and square).Three reduction areas of dies (0.395, 0.555, 0.691) are used. The results show that the extrusion load is effected with reduction area of flat dies more than conical dies when using cone and flat punches while the reduction area of conical dies affected with square punch more than hexagonal punch and this result was inversed with flat dies. The relative extrusion pressure P/Y ̅ increases when the reduction area of conical and flat dies increases too for all punches, but this result contrasts with the square punch at conical dies.The less value of max. stress was found with cone punch of prism angle 120o among cone punches for conical dies except the die of reduction area (0.555) and the cone punch of 90o prism angle gave less max. stress with all flat dies. Flat punch of reduction area (0.444) among the flat punches gave less value of max. stress with all conical dies and flat die of reduction area (0.691).

The Effect of Elastic Deformation of Bearing Surface on The Steady State Performance of Offset Halves Bearing

Ibrahem A.Muhsin

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 12, Issue 2, Pages 122-128

In this research a theoretical study was presented to find the performance of the offset halves bearing which used in applications of high velocities ,like centrifugal machines, dentist tools and high precession machines.
In studying the elastic deformation, three types of alloys have been used for coating the bearing surface. These alloys Cu-alloy, Al- alloy and Mg-alloy. And these show that the bearing material has a considerable effect on the essential bearing characteristics. The bearing made of soft material has lower performance than that made of harder material.
In this work the bearing performance was investigated under the following conditions :
1-Elastohydrodynamic lubrication at a rotational velocity of 2000rpm and L/D ratios
Of(0.5.)and (1)
2-Elastohydrodynamic lubrication at a rotational velocity of 15000rpm and L/D ratios of 0.5and (1).
The results of analysis show that the offset bearing deformation (elastic deformation) has a considerable influence on the performance at a high eccentricity values (n>0.9) i.e. under high loa

Analytical Solution For Buckling of Laminated Conical Shells

Wedad I. Alazzawy

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 12, Issue 2, Pages 129-146

Buckling analysis of laminated conical shells under axial compressive load are investigated analytically using high order and Love ,s shell theories. Power series are used to solve the developed equations of motion for conical shells with different semi vertex angles, length- to – radius ratio, number of layers and boundary conditions. The validity of the presented procedure is confirmed.

Dielectric Properties of Iraqi Clay; Effect of Alumina Content

Qasid Abdul Sattar; Talib Saloom Hamadi

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 12, Issue 2, Pages 147-150

In order to investigate the alumina effect on the low frequency dielectric constant of fire clay manufacture from Iraqi clay. Fire clay products have been powder pressed with different alumina content ,sintered ,then dielectric constant and dielectric loss( tan δ) has been measured at low frequencies which extend from 30 kHz to 100kHz.There is a significant difference in their properties were observed between samples made with different alumina content added to the fire clay product where these differences were measured as a function of alumina content. This confirm that the insulating properties of the fire specimen from the electrical view point was affected by the crystallization of mullite and cristobolite .

Kinetic Study on Vanadium Recovery From Oil Fired Power Stations

Jabber Shanshool; Khalid M. Mousa; Rana K. Obaid

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 12, Issue 2, Pages 151-160

In this work it has been attempted to study the kinetic of vanadium recovery from fly ash by leaching with NaOH solution from previous work of Mosa (1999).
The selected data were chosen at particle size of scale between 125 to 200 µm, temperature 343 to 373 K, reaction (leaching) time up to 8 hours and at about fixed NaOH solution molarity (3 to 4 M).The results show that vanadium recovery increased with time and temperature and mostly decreased with particle size.A second order polynomial mathematical correlation was employed to describe vanadium recovery response. The correlation coefficient of the obtained correlation was 0.9990 and variance of 0.9981 with confidence levels of 95 %.Kinetic study shows that the chemical reaction is the controlling step which has the highest resistance among other steps. A chemical reaction order was found equals to -3 with activation energy of 1080 J/ mole and frequency factor of about 2.6884.

Fracture mechanics and reliability of rupture of cast iron rotating disc

Haider Hadi Jasim

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 12, Issue 2, Pages 161-172

In this paper, the crack propagation in opening mode (Mode I) for three kinds of cast iron rotating disc: Flake graphite cast iron disc, Compacted Vermicular cast iron disc, and Spheroidal graphite cast iron disc are analysed by using Boundary Element Method (BEM) and Finite Element Method (FEM). Weibull uni-axial and multi-axial distribution function is developed and applied to evaluate the reliability of the fracture strength of rotating cast iron disc have inner surface crack. As a result the stress intensity factor (KI) for Flake graphite disc (FGD) is smallest, while (KI) for Spheroidal graphite disc (SGD) was the larger, the value of (KI) for Compacted Vermicular disc (CVD) has intermediate between the two cast iron discs. It is found that there is a convergence between results obtained from uni-axial and multi-axial distribution function, but multi-axial distribution function give high values compared to uni-axial distribution function.
Key words: Stress intensity factor, rotational loading, finite element method, boundary element method.

Flow Model Selection for Water Soluble Polymer Solutions

Muhanned A.R. Mohammed

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 12, Issue 2, Pages 173-187

This research deals with the effect of type and concentration of different polymer solutions on rheological behavior and apparent viscosity. All polymers studied in this work are water soluble, which are: XC-polymer, Carboxymethyl cellulose (two types), Hydroxyethyl cellulose and Polyvinyl alcohol. 55 experiments were performed with different polymer types and concentrations at 30 C (1 C). By using the Solver Add-in in Microsoft Excel®, the power law flow model was found to be the best fits the experimental results. The apparent viscosity of each polymer used at different concentrations was decreased with shear rates. It was found that XC-polymer solutions have higher shear stresses than other polymers. Also it was found that XC-polymer solutions have a higher viscosity, and its viscosity decreases much more than other polymer solutions used in this study.

APPLICATION OF LASER FIBER OPTIC FOR BLOOD VELOCITY MEASURMENT

Munqith S. Dawood; Anwaar A. Al-Dergazly; Sumia H. Jaafer

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 12, Issue 2, Pages 188-194

The aim of this paper is to study the possibility of using laser technique for blood flow velocity measurement using the fiber optics to deliver the laser light and receive the scattered light from the blood flowing in different types of vessels. The measuring technique is based on utilizing the Doppler effect in light by using a He-Ne laser source. The correlation function has been used to consider the scattering light from different erythrocytes. Different angles of transmitted laser inside the vessel were used. It was found that the best angle for all vessels is 45 degrees between the light direction and the direction of blood flow.