Engineering and Technology Journal

In this work ، a CW CO2 laser system was constructed and operated. This
system employs an intermediate heat sink unit in order to increase cooling
rate of the active medium, which is CO2:N2: He mixture. The obtained results
in this work explain that using the heat sink unit causes the output laser
power to increase to 52W compared to 5W obtained from the same system
without using the heat sink unit. This heat sink technique can be considered as
reasonable solution to increase cooling rate of the active medium throughout
forming an intermediate region in which the gas flow rate is high

This work describes the synthesis of 5-(5'-(4-disubstituted amino-butyn-2-
yl)oxy-b-D-ribofuranose) uracil.
For the synthesis of these compounds, 5-(b-D-ribofuranose) uracil was
converted to its 5-(2',3'-O-isopropylidene-b-D-ribofuranose) uracil (1), it
contains the free hydroxyl group at C-5 for the required chemical
modification. Accordingly (1) was prepared from 5-(b-D-ribofuranose) uracil
and acetone using anhydrous ferric chloride (FeCl3) as Lewis acid catalyst.
The treatment of (1) with propargyl bromide in benzene in a phase transfer
conditions in presence of tetrabutyl amonium bromide and 2% sodium
hydroxide solution yielded acetylenic ether derivative 5-(2',3'-Oisopropylidene-
5'-(propyn-2-yl) oxy-b-D-ribofuranose) uracil (2), which was
subjected to Mannich reaction with secondary aliphatic amines and
paraformaldehyde to give the acetylenic amino oxy derivatives (3a-f). The
treatment of (3a-f) with sulfuric acid at room temperature affected selectively
the removal of acetal group at 2',3'-position giving (4a-f) in good yield.
The aim of the present work is the preparation of new carbohydrate
derivatives containing acetylenic amines soluble in water, which possess a
possible biological activity.

Two types of aluminium bronze alloys have been studied to determine the
proper methods of melting and casting in two different conditions; with treating
materials as (Albral 2, Logas 50 and deoxidizing tube E3) and without and
determine the effects of these conditions on mechanical properties of alloys.
These alloys are :-
a) Aluminium bronze alloys (AB1).
b) Nickel-aluminium bronze alloys (AB2).
These alloys were produced using different melting processes and cast method.
The first one was made by preparing the charge materials to be melted and
then, to the cast process without using any types of additions and treatment
materials. The second one was made with casting conditional control, using
proper techniques of casting and using protective layers to minimize the
oxidation and other casting defects. The molten metals from both processes
were poured into two types of moulds; sand and metal moulds, both types were
in dimensions (Ø100×250) mm.
The final products of each type of

Numerical solutions are presented for the transient natural convection heat
transfer problem in horizontal isothermal cylindrical annuli, enclosed in heated
inner and cooled outer cylinders. Solutions for laminar case were obtained within
Grashof number based on the inner diameter which varied from 1x102 to 1x105 in
air. Both vorticity and energy equations were solved using alternating direction
implicit (ADI) method and stream function equation by successive over relaxation
(SOR) method. The structure of fluid flow such as a velocity vector and
temperature distribution as well as Nusselt number were obtained and the effect of
diameter ratio on them was examined. In addition, the Grashof number was
changed with the influence of variation in Prandtle number and diameter ratio. Our
numerical calculation are summarized by Nussult number vs. Grashof number
curves with diameter ratios and Prandtl as a parameter, which serves as a guide to
natural convection heat transfer calculated from annulus. Good agreement with
previous data is obtained.

For lateral-directional stability analysis, the horizontal tail geometric
parameters effect has not been considered. In the present work, the effect of
horizontal tail aspect ratio on the lateral-directional stability derivatives,
rolling static, lateral dynamic stability and Routh discriminate of the airplane
is investigated.
The increasing of the horizontal tail aspect ratio improves both the rolling
static stability and damping ability in the rolling convergence mode and
decreases the damping ability in spiral mode. The results could be used as real
design requirements for further configuration improvements of the airplane

A dynamic model has been developed to study the dynamic behavior of multi
component batch extractive distillation column. The set of equations
governing (material bvalance, heat balance, summation of mole and
equilibrium equations) which represent the dynamic model are solved to give
the temperature and composition profile. Eigenvalue method was used to
integrate the stiff ordinary differential equations.
Matrix method was used to solve many equations simultaeously to redefine
the column parameters during program run. Newtons algorithm was used to
calculate the plate temperatures on each tray.
The calculations and simulations in this paper were obtained by using
MATLAB environment, version 6. The result of the proposed model are
compared with experimental result taken under the same operating
conditions. This model shows good agreement with experimental results and
explains features of the batch extractive distillation process

The focus of this investigation is to study the effect of lubricant viscosity
variation on the performance of the finite width plain journal bearing with
Newtonian and non–Newtonian lubricans in the steady state operation.
Conventional and modified Reynolds equations in two dimensional forms
are solved numerically. The change in viscosity due to temperature
variation, using adiabatic solution, is taken into account.
The results of this work on Newtonian lubricant show that the viscosity
decreases under, at the same load parameter, and causes a decrease in the
shear force and an increase in the side leakage flow rate and eccentricity ratio.
For the non-Newtonian lubricant, at the same nonlinearity factor, the side
leakage flow rate increases due to viscosity variation, while the load capacity
and shear force are decreased

In this paper, a laser ellipsometric method is implemented to study the
formation of oxide films on silicon substrate at room temperature in air. Two
lasers, He-Ne and semiconductor diode, as well as a tungsten halogen lamp,
were used as a light source in this method to show the importance of
coherency for accurate results. The thickness of oxide layer was measured and
the results is compared with that calculated for a monolayer of oxide.
Behavior of thermally formed oxides was studied using ellipsometry to
determine polarizer angle as a function of etching time

In the present work, the effect of different silicon percentages that were
added to Hadfield manganese steel on the microstructure, phases and hardness
are investigated. The results show that silicon has the crucial role in changing the
hardness and Fe3C phase morphology from acicular to chunky through different
stages. X-ray diffraction line profile analysis shows that two phases are presented
in the matrix of Hadfield manganese steels; these phases are austenite and Fe3C

The critical flashover CFO of an insulation structure is commonly used to
describe the insulation structure lightening impulse strength. In this work,
first CFO of polymer and porcelain each alone was measured and then, a new
structural arrangement is represented to measure (CFO). This arrangements
consists of three layers; fiberglass is placed between two layers of polymer and
porcelain .All insulation materials are examined in dry and wet condition with
positive and negative lightening impulse under (15,25 and 35) KV. The critical
flashover voltage (CFO) of insulator is distributed on certain surface along
with fiberglass distribution poles as an insulator. Also altitude of poles is
taken into consideration in calculating critical flashover voltage for both
insulator and structure. (CFO) voltages are added from fiberglass
distribution pole to basic insulation component and are calculated based on
the test result of the (CFO). The above measurements indicated that the total
CFO voltage of new arrangements insulator under dry condition is much
higher than under wet condition for the same impulse polarity and tested pole
length