Print ISSN: 1681-6900

Online ISSN: 2412-0758

Volume 25, Issue 5

Volume 25, Issue 5, July 2007, Page 159-701


Fatigue Damage Accumulation Behavior of 2024 Al-Alloy Under The Effect of Shot Pening Time

Engineering and Technology Journal, 2007, Volume 25, Issue 5, Pages 159-169

Fatigue damage accumulation behavior of 2024 Al-alloy has been investigated
under the effect of varying the time of shot peening. Damage accumulation
from low-high and from high- low stresses has been studied using rotating
bending tests. The time of shoot peening is in the range 2-20 min. The
conclusions derived from this study are:
1. The number of cycles to failure increases as the shot peening time increases
up to about (6-8) min. after that the number of cycles decreases.
2. Surface roughness (Ra) is approximately proportional to the time duration
of shot peening.

Adopting Small Signal Model for the Equivalent Circuit Instrumentation of a Multi-Quantum Wells Semiconductor Laser

Engineering and Technology Journal, 2007, Volume 25, Issue 5, Pages 170-178

In this study, results of an analysis for the MQW semiconductor laser
performance are presented. This analysis considers the steady-state condition
and small signal modeling to introduce optical gain, charge carrier density,
current and output laser power. Accordingly, a description of AC RLC circuit
equivalent to semiconductor laser structure is presented in order to introduce
operation and output parameters as well as achievable efficiencies.

An Investigation of Elastic Buckling for Perforated Plates In Aircraft Structure

Engineering and Technology Journal, 2007, Volume 25, Issue 5, Pages 179-197

The present work performs mechanical buckling analyses on square
and rectangular plates with central cutouts under uniaxial compressive load.
The cutouts were either circular or square holes. The material of plates was
the widely used in aircraft structures i.e. Al-2024 T3 aluminum alloy. The
finite element structure analysis technique was used to study the effects of
plate support conditions, plate aspect ratio , hole geometry, and hole shape on
the buckling characteristics of the perforated plates. The well- known finite
element structural ANSYS program was used to perform the calculations.
Square plates with circular and square cutouts showed decays in buckling
strengths as the hole sizes were increased. On the other hand , rectangular
plates unexpectedly exhibited an anomalous behavior when their buckling
strengths enhanced as the holes were enlarged. The plate buckling mode
shape could be symmetrical or anti-symmetrical, depending on the plate
boundary conditions, aspect ratio and the hole size. For the same cutouts
areas, the buckling strengths of the same sized plates with square holes,slightly, overcome those of the plates with circular holes for moderate hole
sizes. The buckling strengths of the latter cases, however, surpass those of the
former cases when holes are large.

Image Denoising Using Hybrid Transforms

Raghad Aladdin Jassim; Walid Amin Mahmoud

Engineering and Technology Journal, 2007, Volume 25, Issue 5, Pages 669-682

In this paper a new family of transformation for image denoising is
presented, Multiridgelet and Walidlet transforms, which have been proposed
as alternatives to Discrete Wavelet and Multiwavelet transforms.
Walidlet transform is an intelligent tool for solving image processing
problems such as image denoising with straight edges, the general algorithm
of image denoising using discrete multiwavelet transform is introduced, then
followed by the general algorithm of image denoising using Walidlet
transform that is proposed here in order to achieve better results than that for
Walidlet thresholding, finally, a comparative study is presented to show the
differences between a mentioned algorithms.

Measurement of Thermooptic Coefficient in Lead Sulfide Using Laser Single-Beam Scanning Technique

Ban A.M. Bader; Oday A. Hamadi; Afnan K. Yousif

Engineering and Technology Journal, 2007, Volume 25, Issue 5, Pages 683-689

In this work, the single beam scanning technique was employed to express
the nonlinear interaction between laser radiation and semiconductor material
(lead sulfide) as well as to determine the thermooptic coefficient of the
material (lead sulfide). Direct measurement, low cost and reliability are the
main features of this technique. The value of the thermooptic coefficient was
determined to be -5.8x10-5K-1 for PbS thin film. Due to authors review, this is
the first attempt in Iraq to measure such parameter in semiconductor thin
films.

Study of Electrical Properties of p-PbSe/p-Si Heterojunction

Uday Muhsin Nayef

Engineering and Technology Journal, 2007, Volume 25, Issue 5, Pages 690-695

في هذا البحث تم دراسة الخصائص الكهر بائية لكاشف المفرق الهج ين
حيث تم دراسة خصائص تيار - جهد عند الظلام وتبين إن له خصائص p-PbSe/p-Si
تقويمية وذات معامل تقويم منخفض وكذلك أظهرت فولتية انهيار متدرجة في الانحياز العكسي.
ومن قياس سعة – جهد أوضحت أن المفرق من النوع الحاد وتم حساب جهد البناء
.( 0.49 V) حيث بلغ (V= 1 إلى النقطة ( 0 /C2-V الداخلي من خلال اخذ امتداد
تم قياس تيار – جهد في حالة الإضاءة مع الانحياز العكسي ، أبدى الكاشف المصنع سلوك
خطي مع عدم ملاحظة وجود منطقة تشبع.

Photonic Devices Based on Porous Silicon Layers

Uday Muhsin Nayef

Engineering and Technology Journal, 2007, Volume 25, Issue 5, Pages 696-701

The optoelectronic properties of (Al/c-Si) and sandwich structure type
(Al/PS/c-Si/Al) were reported. The nanostructure porous silicon is obtained by
photochemical etching without applying electric field. The photosensitivity of
(Al/PS/c-Si/Al) structure is determined by porous layer photoconduction.
Maximum spectral sensitivity of the porous layer is changed from (575-
610)nm depending on preparation condition.