Abstract: This paper presents the influence of preloading on a)
the contact tractions, b) slip levels and c) stresses at the dovetail
blade-disc interface of an aero-engine through a three-dimensional
(3D) finite element (FE) modeling and analysis. The preloading is
applied by an interference fit at the dovetail interface and the bulk
loading is applied through the rotational speed of rotor. Preloading at
the dovetail interface reduces the peak contact pressure developed
due to bulk loading up to 35%, and reduces the peak contact pressure
and stress difference between top and bottom contact edges.
Increasing the level of preloading reduces the cyclic stress amplitude
at the interface up to certain values of preload and as a consequence,
an improvement in fatigue life could be expected. Fretting damage,
due to vibration and wind milling effect during engine ground
condition, can be minimized by preloading the dovetail interface.
Abstract: MOC (method of cell) is a new method of investigating
wave propagating in material with periodic microstructure, and can
reflect the effect of microstructure. Wave propagation in periodically
laminated medium consisting of linearly elastic layers can be treated
as a special application of this method. In this paper, it was used to
simulate the dynamic response of carbon-phenolic to impulsive
loading under certain boundary conditions. From the comparison
between the results obtained from this method and the exact results
based on propagator matrix theory, excellent agreement is achieved.
Conclusion can be made that the oscillation periodicity is decided by
the thickness of sub-cells. In the end, the NHDMOC method, which
permits studying stress wave propagation with one dimensional strain,
was applied to study the one-dimensional stress wave propagation. In
this paper, the ZWT nonlinear visco-elastic constitutive relationship
with 7 parameters, NHDMOC, and corresponding equations were
deduced. The equations were verified, comparing the elastic stress
wave propagation in SHPB with, respectively, the elastic and the
visco-elastic bar. Finally the dispersion and attenuation of stress wave
in SHPB with visco-elastic bar was studied.
Abstract: The rate of production of main products of the Fischer-Tropsch reactions over Fe/HZSM5 bifunctional catalyst in a fixed bed reactor is investigated at a broad range of temperature, pressure, space velocity, H2/CO feed molar ratio and CO2, CH4 and water flow rates. Model discrimination and parameter estimation were performed according to the integral method of kinetic analysis. Due to lack of mechanism development for Fisher – Tropsch Synthesis on bifunctional catalysts, 26 different models were tested and the best model is selected. Comprehensive one and two dimensional heterogeneous reactor models are developed to simulate the performance of fixed-bed Fischer – Tropsch reactors. To reduce computational time for optimization purposes, an Artificial Feed Forward Neural Network (AFFNN) has been used to describe intra particle mass and heat transfer diffusion in the catalyst pellet. It is seen that products' reaction rates have direct relation with H2 partial pressure and reverse relation with CO partial pressure. The results show that the hybrid model has good agreement with rigorous mechanistic model, favoring that the hybrid model is about 25-30 times faster.
Abstract: In the crack growth analysis, the Stress Intensity
Factor (SIF) is a fundamental prerequisite. In the present study, the
mode I stress intensity factor (SIF) of three-dimensional penny-
Shaped crack is obtained in an isotropic elastic cylindrical medium
with arbitrary dimensions under arbitrary loading at the top of the
cylinder, by the semi-analytical method based on the Rayleigh-Ritz
method. This method that is based on minimizing the potential
energy amount of the whole of the system, gives a very close results
to the previous studies. Defining the displacements (elastic fields) by
hypothetical functions in a defined coordinate system is the base of
this research. So for creating the singularity conditions at the tip of
the crack the appropriate terms should be found.
Abstract: In this paper, we propose a texture feature-based
language identification using wavelet-domain BDIP (block difference
of inverse probabilities) and BVLC (block variance of local
correlation coefficients) features and FFT (fast Fourier transform)
feature. In the proposed method, wavelet subbands are first obtained
by wavelet transform from a test image and denoised by Donoho-s
soft-thresholding. BDIP and BVLC operators are next applied to the
wavelet subbands. FFT blocks are also obtained by 2D (twodimensional)
FFT from the blocks into which the test image is
partitioned. Some significant FFT coefficients in each block are
selected and magnitude operator is applied to them. Moments for each
subband of BDIP and BVLC and for each magnitude of significant
FFT coefficients are then computed and fused into a feature vector. In
classification, a stabilized Bayesian classifier, which adopts variance
thresholding, searches the training feature vector most similar to the
test feature vector. Experimental results show that the proposed
method with the three operations yields excellent language
identification even with rather low feature dimension.
Abstract: Nanomaterials have attracted considerable attention
during the last two decades, due to their unusual electrical, mechanical
and other physical properties as compared with their bulky
counterparts. The mechanical properties of nanostructured materials
show strong size dependency, which has been explained within the
framework of continuum mechanics by including the effects of surface
stress. The size-dependent deformations of two-dimensional
nanosized structures with surface effects are investigated in the paper
by the finite element method. Truss element is used to evaluate the
contribution of surface stress to the total potential energy and the
Gurtin and Murdoch surface stress model is implemented with
ANSYS through its user programmable features. The proposed
approach is used to investigate size-dependent stress concentration
around a nanosized circular hole and the size-dependent effective
moduli of nanoporous materials. Numerical results are compared with
available analytical results to validate the proposed modeling
approach.
Abstract: A new generation of manufacturing machines
so-called MIMCA (modular and integrated machine control
architecture) capable of handling much increased complexity in
manufacturing control-systems is presented. Requirement for more
flexible and effective control systems for manufacturing machine
systems is investigated and dimensioned-which highlights a need for
improved means of coordinating and monitoring production
machinery and equipment used to- transport material. The MIMCA
supports simulation based on machine modeling, was conceived by
the authors to address the issues. Essentially MIMCA comprises an
organized unification of selected architectural frameworks and
modeling methods, which include: NISTRCS, UMC and Colored
Timed Petri nets (CTPN). The unification has been achieved; to
support the design and construction of hierarchical and distributed
machine control which realized the concurrent operation of reusable
and distributed machine control components; ability to handle
growing complexity; and support requirements for real- time control
systems. Thus MIMCA enables mapping between 'what a machine
should do' and 'how the machine does it' in a well-defined but
flexible way designed to facilitate reconfiguration of machine
systems.
Abstract: This paper describes a new approach of classification
using genetic programming. The proposed technique consists of
genetically coevolving a population of non-linear transformations on
the input data to be classified, and map them to a new space with a
reduced dimension, in order to get a maximum inter-classes
discrimination. The classification of new samples is then performed
on the transformed data, and so become much easier. Contrary to the
existing GP-classification techniques, the proposed one use a
dynamic repartition of the transformed data in separated intervals, the
efficacy of a given intervals repartition is handled by the fitness
criterion, with a maximum classes discrimination. Experiments were
first performed using the Fisher-s Iris dataset, and then, the KDD-99
Cup dataset was used to study the intrusion detection and
classification problem. Obtained results demonstrate that the
proposed genetic approach outperform the existing GP-classification
methods [1],[2] and [3], and give a very accepted results compared to
other existing techniques proposed in [4],[5],[6],[7] and [8].
Abstract: The paper presents the Romanian realities and perspectives from the point of view of reaching the sustainable development model in the context of the recent accession to the European Union, based on the analysis of the indicators listed in the EU Sustainable Development Strategy. The analysis of the economic-social potential for sustainable development and of the environment aspects show that the objectives stipulated in the renewed EU Sustainable Development Strategy of 2006 can be reached, but an extra effort must be put-in in order to overcome the existing substantial gaps in several areas in relation to the developed countries of the EU. The paper-s conclusions show that even if sustainable development is not an easy target to reach in Romania, there are resources and a growing potential, which can lead to sustainable development if used rationally.
Abstract: Active research is underway on virtual touch screens
that complement the physical limitations of conventional touch
screens. This paper discusses a virtual touch screen that uses a
multi-layer perceptron to recognize and control three-dimensional
(3D) depth information from a time of flight (TOF) camera. This
system extracts an object-s area from the image input and compares it
with the trajectory of the object, which is learned in advance, to
recognize gestures. The system enables the maneuvering of content in
virtual space by utilizing human actions.
Abstract: To achieve reliable solutions, today-s numerical and
experimental activities need developing more accurate methods and
utilizing expensive facilities, respectfully in microchannels. The analytical
study can be considered as an alternative approach to alleviate
the preceding difficulties. Among the analytical solutions, those with
high robustness and low complexities are certainly more attractive.
The perturbation theory has been used by many researchers to analyze
microflows. In present work, a compressible microflow with constant
heat flux boundary condition is analyzed. The flow is assumed to be
fully developed and steady. The Mach and Reynolds numbers are also
assumed to be very small. For this case, the creeping phenomenon
may have some effect on the velocity profile. To achieve robustness
solution it is assumed that the flow is quasi-isothermal. In this study,
the creeping term which appears in the slip boundary condition
is formulated by different mathematical formulas. The difference
between this work and the previous ones is that the creeping term
is taken into account and presented in non-dimensionalized form.
The results obtained from perturbation theory are presented based
on four non-dimensionalized parameters including the Reynolds,
Mach, Prandtl and Brinkman numbers. The axial velocity, normal
velocity and pressure profiles are obtained. Solutions for velocities
and pressure for two cases with different Br numbers are compared
with each other and the results show that the effect of creeping
phenomenon on the velocity profile becomes more important when
Br number is less than O(ε).
Abstract: This study attempts to investigate the relationship
between internal CSR practices and organizational commitment
based on the social exchange theory (SET). Specifically, we examine
the impact of five dimensions of internal CSR practices on
organizational commitment: health and safety, human rights, training
and education, work life balance and workplace diversity. The
proposed model was tested on a sample of 336 frontline employees
within the banking sector in Jordan. Results showed that all internal
CSR dimensions are significantly and positively related to affective
and normative commitment. In addition, the findings of this study
indicate that all internal CSR dimensions did not have a significant
relationship with continuance commitment. Limitations of the study,
directions for future research, and implications of the findings are
discussed.
Abstract: The paper presents the results of a series of
experiments conducted on physical models of Quarter-circle
breakwater (QBW) in a two dimensional monochromatic wave
flume. The purpose of the experiments was to evaluate the reflection
coefficient Kr of QBW models of different radii (R) for different
submergence ratios (d/hc), where d is the depth of water and hc is the
height of the breakwater crest from the sea bed. The radii of the
breakwater models studied were 20cm, 22.5cm, 25cm, 27.5cm and
submergence ratios used varied from 1.067 to 1.667. The wave
climate off the Mangalore coast was used for arriving at the various
model wave parameters. The incident wave heights (Hi) used in the
flume varied from 3 to 18cm, and wave periods (T) ranged from 1.2 s
to 2.2 s. The water depths (d) of 40cm, 45cm and 50cm were used in
the experiments. The data collected was analyzed to compute
variation of reflection coefficient Kr=Hr/Hi (where Hr=reflected wave
height) with the wave steepness Hi/gT2 for various R/Hi
(R=breakwater radius) values. It was found that the reflection
coefficient increased as incident wave steepness increased. Also as
wave height decreases reflection coefficient decreases and as
structure radius R increased Kr decreased slightly.
Abstract: This paper investigates the relationship between different dimensions of customer relationship management and innovation capabilities in Melli Bank of Iran. Five dimensions of CRM include information sharing, customer involvement, long-term partnership, joint problem solving and technology-based CRM are selected to measure their relationship with innovation capabilities including innovation in product, innovation in process, innovation in administrative affairs, innovation in marketing, and finally innovation in services. Research findings indicate that there is significant relationship between CRM dimensions and innovation capabilities in Melli bank of Iran.
Abstract: The product development process (PDP) in the
Technology group plays a very important role in the launch of any
product. While a manufacturing process encourages the use of certain
measures to reduce health, safety and environmental (HSE) risks on
the shop floor, the PDP concentrates on the use of Geometric
Dimensioning and Tolerancing (GD&T) to develop a flawless design.
Furthermore, PDP distributes and coordinates activities between
different departments such as marketing, purchasing, and
manufacturing. However, it is seldom realized that PDP makes a
significant contribution to developing a product that reduces HSE
risks by encouraging the Technology group to use effective GD&T.
The GD&T is a precise communication tool that uses a set of
symbols, rules, and definitions to mathematically define parts to be
manufactured. It is a quality assurance method widely used in the oil
and gas sector. Traditionally it is used to ensure the
interchangeability of a part without affecting its form, fit, and
function. Parts that do not meet these requirements are rejected
during quality audits.
This paper discusses how the Technology group integrates this
quality assurance tool into the PDP and how the tool plays a major
role in helping the HSE department in its goal towards eliminating
HSE incidents. The PDP involves a thorough risk assessment and
establishes a method to address those risks during the design stage.
An illustration shows how GD&T helped reduce safety risks by
ergonomically improving assembling operations. A brief discussion
explains how tolerances provided on a part help prevent finger injury.
This tool has equipped Technology to produce fixtures, which are
used daily in operations as well as manufacturing. By applying
GD&T to create good fits, HSE risks are mitigated for operating
personnel. Both customers and service providers benefit from
reduced safety risks.
Abstract: The paper addresses a problem of optimal staffing in
open shop environment. The problem is to determine the optimal
number of operators serving a given number of machines to fulfill the
number of independent operations while minimizing staff idle. Using
a Gantt chart presentation of the problem it is modeled as twodimensional
cutting stock problem. A mixed-integer programming
model is used to get minimal job processing time (makespan) for
fixed number of machines' operators. An algorithm for optimal openshop
staffing is developed based on iterative solving of the
formulated optimization task. The execution of the developed
algorithm provides optimal number of machines' operators in the
sense of minimum staff idle and optimal makespan for that number of
operators. The proposed algorithm is tested numerically for a real life
staffing problem. The testing results show the practical applicability
for similar open shop staffing problems.
Abstract: In order to investigate a PROX microreactor
performance, two-dimensional modeling of the reacting flow
between two parallel plates is performed through a finite volume
method using an improved SIMPLE algorithm. A three-step surface
kinetics including hydrogen oxidation, carbon monoxide oxidation
and water-gas shift reaction is applied for a Pt-Fe/γ-Al2O3 catalyst
and operating temperatures of about 100ºC. Flow pattern, pressure
field, temperature distribution, and mole fractions of species are
found in the whole domain for all cases. Also, the required reactive
length for removing carbon monoxide from about 2% to less than 10
ppm is found. Furthermore, effects of hydraulic diameter, wall
temperature, and inlet mole fraction of air and water are investigated
by considering carbon monoxide selectivity and conversion. It is
found that air and water addition may improve the performance of
the microreactor in carbon monoxide removal in such operating
conditions; this is in agreement with the pervious published results.
Abstract: The Cluster Dimension of a network is defined as, which is the minimum cardinality of a subset S of the set of nodes having the property that for any two distinct nodes x and y, there exist the node Si, s2 (need not be distinct) in S such that ld(x,s1) — d(y, s1)1 > 1 and d(x,s2) < d(x,$) for all s E S — {s2}. In this paper, strictly non overlap¬ping clusters are constructed. The concept of LandMarks for Unique Addressing and Clustering (LMUAC) routing scheme is developed. With the help of LMUAC routing scheme, It is shown that path length (upper bound)PLN,d < PLD, Maximum memory space requirement for the networkMSLmuAc(Az) < MSEmuAc < MSH3L < MSric and Maximum Link utilization factor MLLMUAC(i=3) < MLLMUAC(z03) < M Lc
Abstract: Computer worm detection is commonly performed by
antivirus software tools that rely on prior explicit knowledge of the
worm-s code (detection based on code signatures). We present an
approach for detection of the presence of computer worms based on
Artificial Neural Networks (ANN) using the computer's behavioral
measures. Identification of significant features, which describe the
activity of a worm within a host, is commonly acquired from security
experts. We suggest acquiring these features by applying feature
selection methods. We compare three different feature selection
techniques for the dimensionality reduction and identification of the
most prominent features to capture efficiently the computer behavior
in the context of worm activity. Additionally, we explore three
different temporal representation techniques for the most prominent
features. In order to evaluate the different techniques, several
computers were infected with five different worms and 323 different
features of the infected computers were measured. We evaluated
each technique by preprocessing the dataset according to each one
and training the ANN model with the preprocessed data. We then
evaluated the ability of the model to detect the presence of a new
computer worm, in particular, during heavy user activity on the
infected computers.
Abstract: Two-dimensional finite element model was created in this work to investigate the stresses distribution within rock-like samples with offset open non-persistent joints under biaxial loading. The results of this study have explained the fracture mechanisms observed in tests on rock-like material with open non-persistent offset joints [1]. Finite element code SAP2000 was used to study the stresses distribution within the specimens. Four-nodded isoperimetric plain strain element with two degree of freedom per node, and the three-nodded constant strain triangular element with two degree of freedom per node were used in the present study.The results of the present study explained the formation of wing cracks at the tip of the joints for low confining stress as well as the formation of wing cracks at the middle of the joint for the higher confining stress. High shear stresses found in the numerical study at the tip of the joints explained the formation of secondary cracks at the tip of the joints in the experimental study. The study results coincide with the experimental observations which showed that for bridge inclination of 0o, the coalescence occurred due to shear failure and for bridge inclination of 90o the coalescence occurred due to tensile failure while for the other bridge inclinations coalescence occurred due to mixed tensile and shear failure.