Al-Nahrain Journal for Engineering Sciences

The wavelet transform provides good and in
many times excellent results when used as a
basic block transform in many systems such
as electronic, communication, medical and
even chemical systems. The paper uses the
wavelet packet transform to adjust the tap
gains of the adaptive filter used in channel
equalization and estimation. The results using
the wavelet technique achieve good
improvements in convergence time over the
ordinary LMS algorithm. The two systems
were compared on full mathematical and
simulation basis. Learning curves for
adaptive channel equalization and adaptive
channel estimation using wavelet packet
transform with different mother functions,
different level decompositions, different step
sizes, different levels of signal to noise ratio,
different telephone channels and different
filter sizes were compared with conventional
LMS adaptive channel equalization and
channel estimation. The simulation results
carried out using the MATLAB package
version 6.1, demonstrate the efficiency of the
proposed technique.

The present study is a theoretical
analysis to evaluate the static
characteristics of oil filled porous
journal bearing with non uniform
permeability using an improved boundary
condition. The analysis was carried out for
a porous bearing with a permeability of
the bearing ends is lower than that of the
middle. The circumferential boundary
condition for the oil film pressure is
obtained by an integral momentum
equation to the oil film region in the
bearing clearance. It was found that a
porous bearing with anisotropic
permeability enhances the load carrying
capacity of the bearing, also the bearing
oil film is extended along specified extent.

This research deals with experimental
study of the effect of concentration of
polymer solutions on rheological properties.
All polymers studied in this work are water
soluble, which are: XC-polymer,
Carboxymethyl cellulose (two types),
Hydroxyethyl cellulose and Polyvinyl alcohol.
The rheological properties of these polymer
solutions was investigated using a Couette
coaxial cylinder rotational viscometer ( Fann
model 35A ), by measuring shear stresses
versus shear rates (i.e. the flow curve). 55
experiments were performed with different
polymer solutions concentrations at
temperature 30 C ( 1 C). It was found that
as polymer concentration increased, the flow
behavior index (n) decreased and the
consistency index (k) increased. This
behavior reflects the fact that as polymer
concentration increases the solution become
far from Newtonian fluid. Correlations were
found which describe the effect of polymer
concentration on n and k (for each polymer
used in this study) and presented in

The aim of this work is to study the
characterization of ion exchange in important
characteristics (i.e., breakthrough time and
exchange capacity) by investigation the
performance of cation exchange column
subjected to makeup solution in term of three
different parameter (i.e., bed depth 5-45cm,
NaCl salt concentration100-2000 ppm and
feed flow rate 9.5-26.5l/h).
Two second order polynomial model are
proposed with Box Wilson composite rotatable
design. The experimental result had shown an
efficient performance of using ion exchange
column with strong acid cation exchange
resin in fluidized mode operation which given
maximum breakthrough time and higher
exchange capacity means the rate of
exchange is very rapid to completed the
removing of all undesired ions at a condition
of low bed depth, high NaCl concentration
and high feed flow rate.

In this work, a continuous wave
semiconductor diode laser (GaAlAs)
which emits radiation at 810 nm and
power of 2W maximum was used to
ablate caries enamel and dentine from
extracted human teeth in conjunction
with specialized diode laser absorbing dye
indocyanine green . This technique
offers selective ablation with minimal
risk of thermal damage to surrounding
dental tissues because the uptake of the
dye and its irradiation by the diode laser
together control the ablation.
Keywords: Semiconductor laser

The design, construction and operation of a
transversely excited N2 laser using low
inductance capacitors, is presented, the laser
pulse generation is 1200μJ with pulse width 8ns
when operated at about 30mbar with applied
voltage of 15-30 kV. The system is capable of
giving 150 kW peak power. The best values of
specific energy and breakdown voltage are 0.03
J/L and 600 V/cm-mbar respectively.

In this study we show an approach for
wound healing process based on using of
low level laser therapy, in order to enhance
the healing rate of wounds. The low power
laser (LPL) has been introduced also to
solve problems associated with scar
formation after completing the healing
process.
In this study the wound healing process
rate was enhanced by using the illumination
of 650 nm, 5 mW diode laser in CW and 2.5
mW maximum average power pulse modes
with 1 MHz frequency and 50% duty cycle.
The low power laser light biostimulates
the wounded area which was made on the
back of many mice. The healing process was
histologically studied during fourteen days
to find out the differences between the laser
illuminated groups of wounds and other
group of wounds (control).
From the results, we found out that the
pulse diode laser is more efficient than
continuous diode laser in enhancing the
wound healing process within shorter time.