Engineering and Technology Journal

In this study a dynamic model has been developed for two legs walking machine
for analysing the impact process. Energy dissipation in impact process due to leg
contact with the surface was determined. Then the principle of maximum energy
dissipation was applied to find the vertical and horizontal reaction at the points of
contact of legs with the surface. Also the relation between the angle of compass
(legs angle see fig1), the angular velocity prior impact and the vertical and
horizontal reactions at the points of contact is studied in order to determine the
optimumangle that gives a stable walking process and reduces vibration.

Stress analysis problems in geomechanics are ideally suited to the method of boundary
elements, as this technique usually requires a very small number of nodes by
comparison to finite elements. As only the surface of the continuum needs to be
discretized, problems extending to infinity can be described by a very small number
of elements on the soil surface or around a tunnel or excavation . In addition, the
boundary conditions of the infinite domain can be properly defined using boundary
elements, as the technique is based on fundamental solutions valid for unbounded
domains.
Herein, a comparison is made between the finite element method and the boundary
element method in solving two-dimensional stress analysis problems. It is concluded
that the results of the boundary element method are greatly improved when
increasing the number of elements, especially at the regions of stress concentration. A
good agreement can be obtained between the results of the two methods. One must
keep in mind that in the boundary element method, errors due to discretization are
restricted to the boundaries compared to the finite element method where the entire
domain needs to be discretized. This advantage makes the use of the boundary
element method easier and faster.

This paper deals with machining plane determination process for CNC milling
machining. Three methods, Matrix, 3D contour matrix and flow line are
presented. All methods depend on the data set point of the surface matrix of
the workpiece to be machined. All methods can be used to automate the
CAD/CAM operation for roughing process in milling machining. Two surface
examples are included to illustrate all methods. By a comparison among the
three presented methods, a conclusion has been reached that the presented 3D
contour matrix method requires maximum number of blocks to build G-codes
program for CNC tool path programming. It means that, this method requires
longer time to accomplish tool paths. On the other hand the other two
methods require minimum number of blocks of G-codes and shorter time for
roughing.

In this work, results of spot hardening in low-carbon steel by using a pulsed
Nd:YAG laser are presented. These results include determination of
hardening depth, diameter of hardened spot, aspect ratio and heat-affected
zone width with varying laser energy density. In order to determine the effect
of irradiation profile on the overall achievable hardness, the profiles of
overlapping, adjacent and separated hardened spots are compared and the
percent coverage of the workpiece as a function of the laser-hardened spot
dimensions

the present work fabrication and characterization of Cu2S/Si
heterojunction photodiodes made by spray pyrolysis method using aqueous
solution of CuCl2.2H2O onto n-type silicon substrates made. The external
quantum efficiency of heterojunction was ٣7% at wavelength of 850nm. The
experimental results show peak relative responsivity around 100mA/w , and
maximum value of detectivity D* (2*1011cm.Hz1/2.w-1).

In present work, the burning velocity of hydrogen-Air mixtures varies
with hydrogen concentration and initial temperature of the unburned
mixture. Laminar flame speed has been measured experimentally inside tube
using the optical technique. The experimental work was carried out in a prepressure
period in order to apply the density ratio method for calculation of
laminar burning velocity. Mixture strength and unburned mixture
temperature dependence of burning velocity is represented by empirical
function over the ranges of hydrogen concentration (xH2 = 10 – 70 %) and
unburned temperature (Tu = 298K– 348K), which is extended to (473K)
through the previously published data all at a pressure of (1 atm). In
overlapping ranges, the results show good agreement with those previously
published.

The main objective of the present paper is to predict the average delay values
for delayed vehicles at the adjacent entrance and exit gates combination of a
parking garage using a simulation package named STARSIM. Flow level,
number of lanes at each approach of the major road, number of lanes at the
entrance and exit gates, and proportion of parking vehicles from the major
road are taken as the most important factors that affect the performance of the
gates of the car park in term of average delay to be predicted in this paper.
These traffic and geometrical conditions are used to generate a range of delay
values, and the effect of these conditions on the performance of the entrance
and exit gates, in term of delay, is discussed and presented figuratively

This paper describes a three- dimensional nonlinear finite element model
suitable for the analysis of reinforced concrete Beams with Large Opening
under Flexure. The 20-node isoparametric brick elements have been used to
model the concrete. The nonlinear equations of equilibrium have been solved
using an incremental-iterative technique operating under load control. The
solution algorithm used was the modified Newton-Raphson method. The
numerical integration has been conducted using the 27-point Gaussian type
rule. The reinforcing bars are idealized as axial members embedded within
the concrete element and perfect bond between the concrete and the
reinforcement has been assumed to occur. The behavior of concrete in
compression is modeled using an elasto-plastic work hardening model
followed by a perfectly plastic response, which is terminated at the onset of
crushing. In tension, a smeared crack model with fixed orthogonal cracks has
been used with the inclusion of models for the retained post-cracking tensile
stress and the reduced shear modulus. Different types of reinforced concrete
beams with large rectangular transverse openings have been analyzed and the
finite element solutions are compared with the experimental data. Generally,
good agreement has been obtained between the numerical and experimental
load-deflection curves and ultimate load. Numerical studies including some
material parameters such as concrete compressive strength, amount of
longitudinal tensile reinforcement and opening size on the load-deflection
response have been carried out to study their effect on the over all behavior of
reinforced concrete beams with Large opening under Flexure.The finite
element solution revealed that the ultimate load and post-cracking stiffness
increase with the increases of concrete compressive strength, increases with
the increase of the bottom steel reinforcement amount and decreases with the
increase of length or depth of opening

The research presents a proposed method with an algorithm written in
Matlab language to determine the linear equivalence of the pseudo-random
periodic sequences mathematically by using the Laplace transform. The
proposed method enables the computation of the linear equivalence to
determine the degree of the complexity of any periodic sequences produced
from linear or nonlinear key generators. The procedure can be used
comparatively greater computational ease and efficiency. The results of this
algorithm are compared with Berlekamp-Massey (BM) method and good
results are obtained where the results of the Laplace transform are more
accurate than those of (BM) method for computing the linear equivalence (L)
of the sequence of period (p) when (L) is greater than (p/2). Some examples
are given for consolidating the accuracy of the results of this proposed
method.

In this study ,analysis of dust and gas from Al-Kufa cement factory are made.
The effect on the enevironmantal polloution on the town near the factory was
outlined.
The study deals the effect of velocity and direction of the wind on the
polloution using six stations toward the wind direction to Al-Manathera town,
the particles are collected and then analysis these samples.
At last,asutiable recommendations are suggested to reduce the effect of
polloution

The aim of this research is to produce composite materials with ceramic base
covered by a layer of (Al) and its alloys by means of fused deposition technique.
This technique represents new method and combines the powder technology with
the casting technique. Al2O3 poweder was used after having been pressed by
different pressure(58,117 and 176 MPa) in metal molds. The sintering process has
been preformed at 1100 o C for two hours. After that, the porosity percentage has
been measured and the samples were immersed in the molten metals heated to 700o
C . Ultirnatly, these samples were heated to about 1000 o C by a furnace for half an
hour. Then,the samples were cooled to 650 oC and examined by an optical
microscope and the scanning electron microscope. Moreover, the x-ray diffraction
for these sample has been employed to define the structure of the resulting
composite as well as to define the resulting bond between the deposited metal layer
and the ceramic matrix in addition to characterize the existing phases within the
composite material

An experimental and numerical study done to design and analysis ice storage in
air conditioning system on building with three types of cooling load. The design
system was active to produced thermal comfort to the building. The non-operating
hours of the building was defining and used to collect ice on the out surface of
pipes in the ice storage system. To predict the radius of the formatted ice an
enthalpy method used with B.F.C. system used and the results compared with the
experimental results from measuring the radius of the ice formatted in a rig build
and run with the same boundary conditions. The theoretical results shown good
coincident and the small deviation in the magnitude and not the distribution of the
results is because we canceled the convection effect. In the operating hours of the
building many types of pipes arrangement was examined (parallel and staggered),
and many ratios of ( ) L S and ( ) T S in the ice storage. The study shows that the
staggered arrangement is better for the three types of cooling load and always gives
smaller volume of ice storage. In addition, the study shows that any increase in
( ) L S and ( ) T S cause increasing in the volume of ice storage. In addition, the study
shows that the type of cooling load has great effect on the volume of ice storage

This study includes the derivation of the stiffness matrix for a haunched
member using the simple bending theory. The derived stiffness matrix covers
most possible geometric shapes for haunched members under different
loading cases and combinations with including transverse shear deformations
effect.ِ The importance of the transverse shear deformation in haunched
members with high depth to span ratios is shown using numerical example.
The accuracy of the proposed analysis technique is verified by comparing the
results of the numerical example with those obtained from the general
analysis program SAP90 using a large number of subelements

Polyethersulfone (PES) hollow fiber UF membranes were fabricated using
ethanol (non-solvent) as additive and N-methyl-2-pyrrolidone (NMP) as a
solvent. Asymmetric hollow fiber UF membranes were spun by wet phase
inversion method from 18 wt.% solids of 18:10:72 (weight ratio) PES/Nonsolvent/
NMP solutions. Effect of ethanol concentrations in internal coagulant
on morphology and separation performance of PES hollow fiber UF
membranes were investigated. UF membranes were characterized in terms of
scanning electron microscope (SEM) while UF experiments were conducted
using polyethylene glycol (PEG10,000 and 20,000 MW), PVP 40,000MW, and
PVA 78,000MW as a solute. It was found that with an increase of ethanol
concentration from 30 to 50 wt.% in the internal coagulant, membrane
internal surfaces were dense and smooth, While the cracks phenomenon was
appear on the internal surfaces of PES hollow fiber membrane with increase
of ethanol concentration up to 100 wt.% (pure ethanol). The external surfaces
for all of the PES membranes are smooth and dense because water is used as
external coagulant; moreover, there is no change observed in the cross-section
of PES hollow fiber with increase of ethanol concentration in the internal
coagulant. Pure water permeation fluxes were decreased from 39 to 23.3
(L/m2hbar) and solutes rejection increased within less than 50 wt.% ethanol
concentration in internal coagulant and then pure water permeation fluxes
increased up to 65.4 (L/m2hbar) and solutes rejection decreased with an
increase of ethanol concentration

Experimental study of gas holdup (Eg), bubble diameter (dvs) interfacial area
(a) m-1, small bubble rise velocity (Ubs), and bubble rise velocity (Ubr) in (0.1m
i.d) and (1.5m) high column operated at ambient temperature and pressure
conditions. The superficial gas velocity (Ug) was varied in the range of (0-0.3)
m/s, spanning both the homogenous and heterogeneous flow regimes. Air was
used as the gas phase.
Different liquids were used as liquid phase (Water, Ethanol, Butanol, paraffin
oil solutions ).
Experimental results shows that the influence of liquid properties on (Eg) is
considerable, where the lower surface tension (s ) gives a lower (Ubr) and
therefore a higher (Eg). High viscosity (mL
) leads to large bubbles and
therefore a low (Eg) and (a) , for coalescence liquids bubble diameter increases
with increasing gas velocity.
A correlation based on dimensionless groups for the predicition of (Eg) liquid
properties is proposed, and found to be in good agreement with the
experimental data

The fundamentals of free electron laser (FEL) theory are now well–established
and can provide a sophisticated description of experiments over a wide range
of parameters. While new technology is being developed for systems working
from 1mm to 10nm wavelengths, the theory remains the same. In this work,
the final consequences of Lorentzian energy distribution in FEL amplifier will
be found by solving of Integro-differential equation using symbolic toolbox
services in MATLAB software v. 6.5 and the relation between several
parameters will be delimited and plotted in order to extract and present the
complex relations between the FEL parameters

In this paper, a new algorithm for accurate optical flow estimation using discrete
wavelet approximation is proposed. The image sequences are always assumed to
be noiseless in the computation of optical flow, since there is always a method that
can perform such task. One of the main application areas of the wavelet
transform is that of noise reduction in images. The basic technique is to transform
the noisy input image into a domain, in which the main signal energy is
concentrated into as few coefficients as possible, while the noise energy is
distributed more uniformly over all coefficients. The choice of the transform is
represent an important tool in optical flow estimation. In this paper, several
algorithms of 1-D, 2-D and 3-D wavelet transforms are adapted for the estimation
of optical flow for the first time

This investigation examines experimentally and statistically the behavior
and ultimate strength of L-shape reinforced high strength concrete beams
under combined bending and shear. The experimental investigation consists of
casting and testing of nine beams which were tested under bending and shear.
The effect of compressive strength, longitudinal reinforcement on the load carry
capacity and the effect of transverse reinforcement on the shear strength is
studied. An increase in compressive strength by (65.56%) causes an increase in
load carrying capacity and shear strength at cracking load by (21.47% and
162.9%) respectively. An increase in longitudinal reinforcement ratio for
bending by (153.8%) caused an increase in load carrying capacity by (46.37%)
when the longitudinal reinforcement ratio is kept constant, an increase in
transverse reinforcement index by(59.25% %) causes an increase in shear
strength at ultimate load by (6.55 %).
By using multiple nonlinear stepwise regression method, based on data in
this research and from other literature; equations were proposed for predicting
shear strength at cracking and ultimate loads. These proposed equations show
good agreement and they are conservative when compared with equations given
by Codes of practice.