Iraqi journal of mechanical and material engineering

In Magnetic Abrasive Finishing (MAF) process the cutting temperature is generated from two
sources, from the electromagnetic flux (electrical heat), and from magnetic abrasive brush due to
the friction force (mechanical heat). The cutting temperature has significant effects upon the
condition of the surface, whereas it is less studied than the other parameters.
In this study, an attempt has been made to simulate and investigate the influence of cutting
parameters on the cutting temperature, to improve the thermal effect by MAF process. The aims
of this study was to determine the distribution of the cutting temperature in the working gap,
numerically and experimentally, then compared the results. In addition, to determine the most
influence parameters affecting on the cutting temperature for Brass alloy CuZn28.
Two dimensional Finite Element Models (FEM) with two software’s were developed to
predict the temperature by dynamic electric and magnetic field, the first was DEFORM 10.2 used
to calculate the mechanical heat and the second was COMSOL5.2 used to calculate the electrical
heat. Sixteen tests designed according to Taguchi matrix through the orthogonal array (OA) L16
( ). There are four various parameters that, have a large impact on cutting temperature, with
four levels (rotational speed (A), working time (B), current (C), and working gap (D)). The
analysis of the variance (ANOVA) technique was utilized to analysis the results, by using the
statistical software (MINITAB-17).
From the results, it is concluded that the Numerical modeling gives a very good comparison
with the values of experimental tests. The maximum difference between the numerical and
experimental temperature for brass CuZn28 is less than (9%).

The paper presents the effect of convergent-divergent nozzles profile across
specified inlet pressures values from (1.5 bar-4 bar), with constant back pressure of (1
bar). The flow of air through three convergent-divergent nozzles was studied theoretically.
The flow was assumed to be one-dimensional, adiabatic and reversible (isentropic). The
flow parameters like static pressure ratio and Mach number were analyzed. The flow
parameters were obtained in term of area ratio along the nozzle. MATLAB code was built
in order to find the Mach number along the nozzles, by using Newton-Raphson method.
The shockwave position inside the nozzles was determined, using \"analytic method\".
ANSYS fluent 18 was used to simulate the flow through the three nozzles. Twodimensional, turbulent and viscous models were utilized to solve the governing
equations. K-ε model was used to model the turbulent effect. The results concluded that,
reduction in inlet pressure can not affect the flow upstream the throat. Also the
shockwave appearance can be noticed by a sudden rise in static pressure associated with a
sharp decrease in Mach number. Shockwave moves toward the throat by reduction the inlet
total pressure .By comparison the static pressure distribution along the three nozzles where
can be deduced that the profile has an effect on the flow character i.e. (static pressure Mach
no).The best performance among the nozzles is the performance of nozzle (N1), which
(75%) of its length work as nozzle at the lowest inlet pressure of (1.5bar) while (44% and
60%) of the nozzles length for (N2 and N3) respectively work as the nozzle.

The effects of lubricant temperature on the dynamic behaviour of Nano-lubricated finite
length journal bearings has been investigated in the present work. Modified time dependent
Reynolds equation include the effect of oil film temperature was perturbed in order to
calculate the eight dynamic coefficients (four stiffness, and four damping) required to
evaluate the dynamic characteristics of the journal bearing, the oil film temperature was
obtained by solving numerically the energy and heat conduction equations simultaneously
with the Reynolds equation using appropriate boundary conditions. Suitable viscosity
temperature model has been used to consider the effect of oil film temperature. The bearing
lubricated with oil containing Titanium dioxide (TiO2 ) nanoparticles dispersed in to the
base oil with various particle concentration. The effect of adding TiO2 Nano-particles with
various particle concentrations (0.1%, 0.5%, 1%, 1.5% and 2%) in order to enhance its
viscosity has been discussed. A validation to the mathematical model and the computer
program written in Fortran90 prepared to solving the governing equation has been carried
out by comparing the result for the dynamic coefficients (stiffness and damping) obtained in
the present work with that obtained by Sheeja and Prabhu . The results seen to be in a good
agreement with percentage of error less than 2%. The results obtained in the present study
show that the bearing stiffness coefficients increases by 30% while the damping coefficients
increased by 27% when the bearing lubricated with Nano lubricant that contains TiO2 Nano
particles with particle concentration of (1.5%)

From the time being, there are even instances for application of mobile robots in our life
like in home, schools, hospitals, etc. The goal of this paper is to plan a path and minimizing the
path lengths with obstacles avoidance for a mobile robot in static environment. In this work we
depict the issue of off-line wheeled mobile robot (WMR) path planning, which best route for
wheeled mobile robot from a start point to a target at a plane environment represented by 2-D
work space. A modified optimization technique to solve the problem of path planning problem
using particle swarm optimization (PSO) method is given. PSO is a swarm intelligence based
stochastic optimization technique which imitate the social behavior of fish schooling or bird
flocking, was applied to locate the optimum route for mobile robot so as to reach a target.
Simulation results, which executed using MATLAB 2014 programming language, confirmed
that the suggested algorithm outperforms the standard version of PSO algorithm with the same
environment conditions by providing the shortest path for mobile robot

Cell Formation (CF) problem considers as the most important issue in the Cellular
Manufacturing (CM) system particularly the design step. CF deals with the creation of
machine cells (MCs) and part families (PFs). Numerous methods, algorithms and
mathematical models were proposed and used in the literature for solving the CF problem.
The current paper used a heuristic method based on the hamming distance to form MCs
&PFs, this proposed method calculates the hamming distance for the parts, firstly then
rearranges them based on the results to shape the PFs. Afterward, the hamming distance was
calculated for machines, then the machines rearranged based on the results to form the MCs.
Three datasets from the literature were utilized to validate the proposed method. Five
performance measures were used for comparison and evaluation, these measures are
Exceptional Elements EE, Percent of Exceptional elements PE, Voids, Grouping Efficiency
GE and Machine Utilization MU. The results referred to the outperforms of the hamming
distance based method comparing with the best known results in the literature. Among the
total 20 performance indexes: three are better than, twelve are equal to and five are almost
equivalent to the best known results. On the other hand, the proposed hamming distance
based method is effectual particularly in terms of the number of machine cells and PE.

Multipoint forming is an engineering concept which means that the working surface of the die
and/or punch is made up of hemispherical ends of individual active elements (called pins), where
each pin can be independently, vertically displaced using a geometrically reconfigurable die,
precious production time is saved because several different products can be made without
changing tools. The aim of this work is to present the effect of many parameters (blank Holder
types, rubber thickness and forming speed) on the reduction of thickness for brass with 0.71 mm
thickness. This research is concentrate on the development of predictive models to estimate the
minimum deviation in thickness using analysis of variance (ANOVA), minimum thickness
deviation has been modeled. In the development of this predictive model, blank holder, rubber
thickness and forming speed have been considered as model parameters. Arithmetic the
minimum thickness deviation used as response parameter to assess the thickness reduction of
Multipoint forming parts. The data required has been generated, compared and evaluated to the
proposed models that obtained from experiments. Taguchi algorithm is used to predict the
effect of forming parameters on thickness reduction in forming process of Brass (65-35) based
on orthogonal array of L9. The analysis of variance was used to find the best factors that effect
on the thickness deviation, The result of this research is the contribution of blank holder types,
rubber thickness and forming speed with respect to minimum thickness deviation is (69.195,
18.1 and 12.733) % respectively.

Denture base is the part of a denture that rests on the foundation tissues and to which teeth are
Attached. Denture base may be complete or partial used for the alteration of missing natural teeth.
The most popular material utilized for the fabrication of dentures base is the poly (methyl
methacrylate) (PMMA) because is distinguished by many characteristic. The remarkable clarity of
a methyl methacrylate resin, its relatively high strength and hardness, its color stability under all
conditions of dental use, its insolubility in the mouth fluids, all of these properties combine to
provide an excellent material for the prosthetics denture (S. S Carmen, 2010 and R. K. Alla 2013).
This survey illustrate the effect of particle size of powders and weight fraction of natural Bamboo
and Rice Husk powders on PMMA, with the selected size particles of (25µm and 75µm) and
weight fraction (2, 4, 6 and 8wt. %), on compression strength and hardness, and these experience
were accomplished at a temperature of laboratory. The results showed improved in the hardness
and compression with concentration rate of Rice Husk and Bamboo powders in composite
samples. Also, the highest values of compressive strength and hardness were (300MPa.) and (86)
respectively for (PMMA-8%RH) and particle size (25 µm).