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Issue 1, Volume 7,
January 2012
Title of the Paper:
Plane Wave Based Method: Analytic Integration and
Frequency Behaviour
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Authors: Soufien
Essahbi, Emmanuel Perrey-Debain, Mabrouk Ben Tahar, Lotfi Hammami, Mohamed
Haddar
Abstract: This paper deals with 2D acoustic problem. In order to study this
problem, a finite element enriched by a plane wave base is used. This work
focus on two aspects. Firstly, the study of this element depending on the
frequency. Secondly, the description of an analytic integration technique. Two
examples are studied, the first resemble to car cavity and the second resemble
to rectangular duct. A comparison between numerical results obtained by
standard finite element and enriched finite element are done, for the first
one. And, for the second example, a comparison between numerical results
obtained by the use of enriched finite element and analytic results are
presented. With this work, the results found show that the performance of the
enriched finite element increases while increasing the frequency, in the same
way for the analytic integration.
Keywords: Helmholtz
equation, Finite elements, Plane wave basis, Frequency behaviour, Analytic
integration, GAUSS integration
Title of the Paper:
Algorithm of the Maintenance Activities Optimization
with an Approximate Solution to the Problem of Scheduling Preventive Task
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Authors: Aissam
Aboussalim, Mohamed Mediouni
Abstract: Maintenance is a factor of competitivity since it affects the
production, quality and cost.
It is essential for the increasing development of the company and its assets.
The approach presented in this paper is a contribution to research related to
the scheduling of maintenance tasks, to the allocation of resources and to the
optimization of maintenance costs. This work proposes an algorithm based on:
the real-time decision, the planning of maintenance tasks, the allocation of
tasks to the appropriate resources under the constraints of the tasks duration
and skills, and at the same time minimizing the cost of maintenance service.
The criterion for maintenance optimization is evaluated by the sum of advances
/ delays of preventive maintenance cost by including other tasks, dynamic or
delays, in elementary windows
Keywords: Tasks,
preventive maintenance, scheduling, optimization, resource, cost
Title of the Paper:
Distinguishing Profile Deviations from a Part’s
Deformation Using the Maximum Normed Residual Test
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Authors: Ali Aidibe,
Antoine S. Tahan, Gad N. Abenhaim
Abstract: Non-rigid parts, in free-state, may have a considerable different
shape than their nominal model due to dimensional and geometric variations of
manufacturing process, gravity loads and residual stress induced distortion.
Therefore, sorting profile deviation from a part's deformation by comparing
the part's nominal shape to its scanned free-state shape is a challenging
task. This task is a key step in the Iterative Displacement Inspection (IDI)
algorithm used for the inspection of non-rigid parts without the use of costly
specialized fixtures. This paper proposes the use of the statistical maximum
normed residual test to improve the aforementioned identification task. Thirty
two simulated manufactured parts are studied to show that the proposed method
reduces the type I and II identification error of the IDI method.
Keywords: Rigid
registration, non-rigid registration, quality control, tolerancing,
inspection, metrology, non-rigid parts, deformation, Geometric dimensioning
and tolerancing (GD&T)
Title of the Paper:
Determination of Relaxation and Retardation Spectrum
from Modulus of Complex Frequency-Domain Material Functions
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Authors: Vairis
Shtrauss, Aldis Kalpinsh
Abstract: The paper is devoted to improving and simplifying determination of
the relaxation and retardation spectrum (RRS). A concept is postulated that
determination of RRS from some specially selected material responses differing
from the explicitly defined material functions, such as the real or imaginary
parts of complex compliance and complex modulus, may improve the recovery
performance at the price of better measurability of these specific material
responses. As one of possible implementations of the postulated concept, we
propose to recover RRS from the modulus (absolute value) of a complex
frequency-domain (dynamic) material function, which, compared to the real or
imaginary part, can be more accurately and easy acquired by measuring the
amplitudes of harmonic responses of a material. It is demonstrated that RRS
recovery problem from the modulus of a complex frequency-domain material
function may be interpreted as a filtering task with a diffuse magnitude
response bounded by the responses of the Mellin deconvolution filters
corresponding to the minimum (zero) and maximum imaginary parts according to
the Kramers-Kronig relation. A discrete RRS recovery filter operating with
geometrically sampled data is constructed for recovering RRS from the modulus
and the simulation results are presented. A measurement system is proposed
implementing RRS recovery through the modulus of a complex frequency-domain
material function, where a material under test is subjected to multi-harmonic
excitation at geometrically spaced frequencies with subsequent measuring the
amplitudes of multi-harmonic responses and processing them by a discrete RRS
recovery filter.
Keywords: Relaxation and
Retardation Spectrum (RRS), Modulus of a Complex Frequency-Domain Function,
Complex Compliance, Complex Modulus, Mellin Deconvolution Filter, Diffuse
Magnitude Response
Title of the Paper:
Nonlinear Static Analysis to Assess Seismic Performance
and Vulnerability of Code - Conforming RC Buildings
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Authors: A. Cinitha, P.
K. Umesha, Nagesh R. Iyer
Abstract: The seismic zone map of Indian subcontinent emphasis that more than
60% of land is under severe to moderate earthquake and approximate hábitat
requirement is 20-25 lakhes of buildings in each year. The adequacy of post
occupancy of buildings after an earthquake is highly demanded. This paper
investigates seismic performance and vulnerability analysis of 4-storey and
6-storey code-conforming (IS: 456-2000, Indian standard for plain and
reinforced concrete code and IS: 1893-2002, Indian standard criteria for
earthquake re-sistant design of structures) reinforced concrete (RC)
buildings. The buildings are designed for two different cases such as ordinary
moment resisting frame (OMRF) and special moment resisting frame (SMRF). The
non-linear static analysis (pushover analysis) is used to capture initial
yielding and gradual progressive plastic be-haviour of elements and overall
building response under seismic excitations. The deformation characteristics
of structural elements are essential to simulate the plastic hinge formation
in the process of generation of capacity curve during the pushover analysis.
An analytical procedure is developed to evaluate the yield, plastic and
ulti-mate rotation capacities of beams and columns along with different
plastic hinge lengths. In the present study, user defined plastic hinge
properties of beams and columns are modeled using analytical expressions
developed based on Eurocode 8 and incorporated the same in pushover analysis
using SAP2000. The nonlinear static analysis is carried out for load patterns
proportional to fundamental mode. The analysis gives an estimate of seismic
capacity of the structural system and its components based on its material
characteristics and detailing of member dimensions. A 100% dead load plus 50%
live load is applied prior to the lateral load in the push-over analysis. The
building performances are assessed with the capacity curve generated.
Performance levels are used to describe the limiting damage condition, which
may be considered satisfactory for a building under specific earthquake. The
performance levels are expressed in terms of target displacement, defined by
limiting values of roof drift, as well as deformation of structural elements.
The three performance levels considered in the present study are immediate
occupancy, life safety and collapse prevention. The vulnerability of the
buildings is estimated in terms of vulnerability index to assess the
performance of the building.
Keywords: Post occupancy,
Plastic hinge length, Seismic performance, Nonlinear static analysis,
Perform-ance levels, Vulnerability index
Title of the Paper:
Numerical Study of Transition Process in a Separated
Boundary Layer on a Flat Plate with Two Different Leading Edges
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Authors: Zhiyin Yang
Abstract: Transition from laminar flow to turbulent flow occurs very often and
plays a crucial role in many practical engineering flows. There are many
different kinds of transition and broadly speaking they can be classified into
three categories: classical transition in attached boundary; bypass transition
in attached boundary layer and separated boundary layer transition. This paper
presents a comparative study of separated boundary layer transition on a flat
plate with a blunt/semi-circular leading edge. Boundary layer may separate due
to an adverse pressure gradient or due to flow geometry. In the current study
the geometry is a flat plate with two different leading edges: a blunt one and
a semi-circular one. The main purpose of the study is to identify how similar
or how different the transition process is with two different leading edges.
This study shows that for both cases (blunt and semi-circular leading edges)
the primary two-dimensional instability originates from the free shear layer
of the separation bubble via the Kelvin-Helmholtz mechanism. Three-dimensional
motions develop under any small spanwise disturbances and similar coherent
structures have been observed from flow visualization in both cases, strongly
indicating that the transition process is very similar.
Keywords: Large-Eddy
Simulation (LES), transition process, free shear layer, instability
Title of the Paper:
Assisted Creative Robot Arm Assembly and Control Program
Design
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Authors: Meng-Hui Hsu,
Ting-Sheng Weng
Abstract: Applied techniques in smart robots implicates various basic and
applied courses in different fields, activities relating to education on
high-tech smart robots are good methods to inspire students to become
outstanding technological personnel. Thus, this study used training activities
based on the creative DIY Lego robot block combination designs, and in turn,
used the program design to control the robotic arm actions of Lego robots in
order to cultivate student ability in understanding and applying principles of
robotic movement and control. This study intended that students would apply
creative, inventive abilities to solve problems, produce innovative ideas, and
new design methods for games.
This study aimed to teach students to learn the basic principles of robotic
movement, the writing, and design of Java code, and in turn, complete
repetitive works for controlling robotic arms to pick up objects at fixed
points, move them, and place them. These activities can inspire student
concepts in using robots to replace human resources and related applied
technologies, and is intended to educating students to engage in new
beneficial research relating to robots.
Keywords: Robots, Robot
arms, Creative combination, Assisted computer programming language
instruction, Java
Issue 2, Volume 7,
April 2012
Title of the Paper:
Fuzzy-Rule-Based Faults Classification of Gearbox
Tractor
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Authors: Shaban Ghavami
Jolandan, Hossein Mobli, Hojat Ahmadi, Mahmoud Omid, Seyed Saeid Mohtasebi
Abstract: This paper presents a fault Classification method based on a fuzzy
inference system. The vibration signal from a piezoelectric transducer is
captured for the following conditions of MF 285 gearbox: ‘Healthy Gearbox’
(H), ‘Gear with tooth face worn’ (W) and ‘Gear with tooth face broken’ (B), at
three working speed (700, 1500 and 1800 rpm). The features of signal were
extracted using descriptive statistic parameters. The output of the J48
algorithm is a decision tree that was employed to produce the crisp if-then
rule and membership function sets. Results showed that the total
classification accuracy for 700, 1500 and 1800 rpm conditions were about
79.63%, 100% and 96.3%.
Keywords: Vibration-Based
Condition Monitoring, J48 Algorithm, Gearbox, Fuzzy, Tractor, Fault
Title of the Paper:
Study of Workpiece Thermal Profile in Electrical
Discharge Machining (EDM) Process
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Authors: Ali
Moarrefzadeh
Abstract: Electric Discharge Machining (EDM) removes metal with sparks. A
shaped graphite or copper electrode is used to make a cavity that is the
mirror image of the electrode, without direct contact with the workpiece.
Sparks travel through a dielectric fluid, typically a light oil, at a
controlled distance. EDM can machine cavities with thin walls and fine
features, achieve difficult part geometry, produce burr-free parts, and is
insensitive to workpiece hardness.The values of these parameters significantly
affect such machining outputs as material removal rate and electrodes wear. In
this paper, the mathematical relationships between input and output parameters
of EDM are established using regression method and the best set of models is
chosen. Genetic Algorithm is then used to optimally determine input parameters
levels in order to obtain any desired set of outputs. Numerical simulation of
process in ANSYS software an for gaining the thermal profile, the effect of
parameter variation on temperature field and process optimization are done.
The numerical results show the time-dependant distributions of arc pressure,
current density, and heat transfer at the workpiece surface are different from
presumed Gaussian distributions in previous models.
Keywords: EDM parameters,
Workpiece, Discharge, Machining, ANSYS
Title of the Paper:
Machine Tools Foundation Static and Free Vibration
Analyses
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Authors: Thamir Salah,
Suhair G. Hussain, Wedad AlAzzawy
Abstract: Machine tools foundations are very important element of these
machine structures. Deformations for foundations under static load are studied
in present work, the effect of changing stiffening plates shape and cutting
conditions such as type of cutting process and angle of cutting forces on
these deformation are investigated using finite element program (ANSYS5.4)
also effects of these parameters on the foundation natural frequencies are
obtained.
Keywords: machine tools,
foundations, free vibration, static analyses, structure, finite element method
Title of the Paper:
Simulation and Modeling of Physical Vapor Deposition
(PVD) Process
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Authors: Ali
Moarrefzadeh
Abstract: The deposition of thin film layers from the vapor phase is
accomplished through several techniques. We review the physical vapor
deposition (PVD) techniques and equipment that are in common use in the
high-volume production of coatings that find application in the optical,
display, decorative and tribological. Specific PVD processes and coating
materials have been developed and optimized for each application. It is well
established that low pressure physical vapor deposition processes such as
thermal evaporation and the many variants of sputtering utilize nearly
collision less vapor transport to a substrate. This results in line-of-sight
deposition. The deposition of uniform coatings on complex shapes using these
approaches therefore requires substrate rotation or a multiple evaporation
source strategy. In many cases, the line-of-sight requirement precludes the
use of these processes entirely. Recently, developed rarefied gas jet based
deposition processes, however, operate at much higher pressures where many gas
phase collisions occur. Direct simulation Monte Carlo (DSMC) simulations have
been used to understand the fundamental phenomena involved and to identify the
role of the process conditions on the coating’s uniformity.
Keywords: Modeling,
Simulation, workpiece, coating, Surface, PVD
Title of the Paper:
TVD Flux Vector Splitting Algorithms Applied to the
Solution of the Euler and Navier-Stokes Equations in Three-Dimensions – Part I
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Authors: Edisson Sávio
De Góes Maciel
Abstract: In the present work, the Steger and Warming, the Van Leer, the Liou
and Steffen Jr. and the Radespiel and Kroll schemes are implemented, on a
finite volume context and using a structured spatial discretization, to solve
the Euler and the Navier-Stokes equations in three-dimensions. A MUSCL
(“Monotone Upstream-centered Schemes for Conservation Laws”) approach is
implemented in these schemes aiming to obtain second order spatial accuracy
and TVD (“Total Variation Diminishing”) high resolution properties. An
implicit formulation is employed to the Euler equations, whereas the
Navier-Stokes equations use an explicit formulation. The algebraic turbulence
models of Cebeci and Smith and of Baldwin and Lomax are implemented. The
problems of the supersonic flow along a compression corner (inviscid case),
and of the supersonic flow along a ramp (viscous case) are solved. The results
have demonstrated that the most severe and most accurate results are obtained
with the Liou and Steffen Jr. TVD scheme. The turbulent results are presented
in the second part of this work.
Keywords: Steger and
Warming algorithm, Van Leer algorithm, Liou and Steffen Jr. algorithm,
Radespiel and Kroll algorithm, TVD high resolution schemes, Turbulence models,
Euler and Navier-Stokes equations, Three-Dimensions
Title of the Paper:
TVD Flux Vector Splitting Algorithms Applied to the
Solution of the Euler and Navier-Stokes Equations in Three-Dimensions – Part
II
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Authors: Edisson Sávio
De Góes Maciel
Abstract: In the present work, the Steger and Warming, the Van Leer, the Liou
and Steffen Jr. and the Radespiel and Kroll schemes are implemented, on a
finite volume context and using a structured spatial discretization, to solve
the Euler and the Navier-Stokes equations in three-dimensions. A MUSCL
(“Monotone Upstream-centered Schemes for Conservation Laws”) approach is
implemented in these schemes aiming to obtain second order spatial accuracy
and TVD (“Total Variation Diminishing”) high resolution properties. An
implicit formulation is employed to the Euler equations, whereas the
Navier-Stokes equations use an explicit formulation. The algebraic turbulence
models of Cebeci and Smith and of Baldwin and Lomax are implemented. The
problems of the supersonic flow along a compression corner (inviscid case),
and of the supersonic flow along a ramp (viscous case) are solved. The results
have demonstrated that the most severe and most accurate results are obtained
with the Liou and Steffen Jr. TVD scheme. The first paper of this work treats
the inviscid and laminar viscous results. In this paper, the second of this
series, the turbulent results are presented.
Keywords: Steger and
Warming algorithm, Van Leer algorithm, Liou and Steffen Jr. algorithm,
Radespiel and Kroll algorithm, TVD high resolution schemes, Turbulence models,
Euler and Navier-Stokes equations, Three-Dimensions
Title of the Paper:
Windage Power Loss in Spur Gear Sets
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Authors: Fakher Chaari,
Manel Ben Romdhane, Walid Baccar, Taher Fakhfakh, Mohamed Haddar
Abstract: The windage power loss in gear transmission systems at high speeds
can be significant and must be taken into account at the design stage in order
to optimize the geometrical shape of the gear’s bodies to improve the
mechanical efficiency. The main objective of this work is, first, to propose a
design of a two-dimensional geometry of the spur gear using the commercial
Computational Fluid Dynamics (CFD) Fluent 6.3.26 which enable us to detect the
pressure and viscous moments due to the aerodynamic drag of the teeth in the
airlubricant mixture. In addition, a parametric study concerning the influence
of the geometrical shape of teeth and the lubricant on the evolution of the
windage power losses on the gear teeth is carried out.
Keywords: windage power
loss, spur gear, CFD, lubrication, addendum modification
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