Abstract: Springback is a significant problem in the sheet metal
forming process. When the tools are released after the stage of
forming, the product springs out, because of the action of the internal
stresses. In many cases the deviation of form is too large and the
compensation of the springback is necessary. The precise prediction
of the springback of product is increasingly significant for the design
of the tools and for compensation because of the higher ratio of the
yield stress to the elastic modulus.
The main object in this paper was to study the effect of the
anisotropy on the springback for three directions of rolling: 0°, 45°
and 90°. At the same time, we highlighted the influence of three
different metallic materials: Aluminum, Steel and Galvanized steel.
The original of our purpose consist on tests which are ensured by
adapting a U-type stretching-bending device on a tensile testing
machine, where we studied and quantified the variation of the
springback according to the direction of rolling. We also showed the
role of lubrication in the reduction of the springback.
Moreover, in this work, we have studied important characteristics
in deep drawing process which is a springback. We have presented
defaults that are showed in this process and many parameters
influenced a springback.
Finally, our results works lead us to understand the influence of
grains orientation with different metallic materials on the springback
and drawing some conclusions how to concept deep drawing tools. In
addition, the conducted work represents a fundamental contribution
in the discussion the industry application.
Abstract: Laser Doppler flowmetry is a modern method of noninvasive
microcirculation investigation. The aim of our study was to
use this method in the examination of patients with secondary
lymphedema of the lower extremities and obliterating atherosclerosis
of lower extremities. In the analysis of the amplitude-frequency
spectrum of secondary lymphedema patients we have identified
remarkable changes. To describe the changes we used a special
amplitude rate. In both of patients groups this rate was significally
(p
Abstract: The paper aims at investigating influence of medium
capacity on linear adsorbed solute dispersion into chemically
heterogeneous fixed beds. A discrete chemical heterogeneity
distribution is considered in the one-dimensional advectivedispersive
equation. The partial differential equation is solved using
finite volumes method based on the Adam-Bashforth algorithm.
Increased dispersion is estimated by comparing breakthrough curves
second order moments and keeping identical hydrodynamic
properties. As a result, dispersion increase due to chemical
heterogeneity depends on the column size and surprisingly on the
solid capacity. The more intense capacity is, the more important
solute dispersion is. Medium length which is known to favour this
effect vanishing according to the linear adsorption in fixed bed seems
to create nonmonotonous variation of dispersion because of the
heterogeneity. This nonmonotonous behaviour is also favoured by
high capacities.
Abstract: This paper presents PSS (Power system stabilizer) design based on optimal fuzzy PID (OFPID). OFPID based PSS design is considered for single-machine power systems. The main motivation for this design is to stabilize or to control low-frequency oscillation on power systems. Firstly, describing the linear PID control then to combine this PID control with fuzzy logic control mechanism. Finally, Fuzzy PID parameters (Kp. Kd, KI, Kupd, Kui) are tuned by Genetic Algorthm (GA) to reach optimal global stability. The effectiveness of the proposed PSS in increasing the damping of system electromechanical oscillation is demonstrated in a one-machine-infinite-bus system
Abstract: The industrial process of the sugar cane crystallization produces a residual that still contains a lot of soluble sucrose and the objective of the factory is to improve its extraction. Therefore, there are substantial losses justifying the search for the optimization of the process. Crystallization process studied on the industrial site is based on the “three massecuites process". The third step of this process constitutes the final stage of exhaustion of the sucrose dissolved in the mother liquor. During the process of the third step of crystallization (Ccrystallization), the phase that is studied and whose control is to be improved, is the growing phase (crystal growth phase). The study of this process on the industrial site is a problem in its own. A control scheme is proposed to improve the standard PID control law used in the factory. An auto-tuning PID controller based on instantaneous linearization of a neural network is then proposed.
Abstract: Bumpers play an important role in preventing the
impact energy from being transferred to the automobile and
passengers. Saving the impact energy in the bumper to be released in
the environment reduces the damages of the automobile and
passengers.
The goal of this paper is to design a bumper with minimum weight
by employing the Glass Material Thermoplastic (GMT) materials.
This bumper either absorbs the impact energy with its deformation or
transfers it perpendicular to the impact direction.
To reach this aim, a mechanism is designed to convert about 80%
of the kinetic impact energy to the spring potential energy and
release it to the environment in the low impact velocity according to
American standard1. In addition, since the residual kinetic energy
will be damped with the infinitesimal elastic deformation of the
bumper elements, the passengers will not sense any impact. It should
be noted that in this paper, modeling, solving and result-s analysis
are done in CATIA, LS-DYNA and ANSYS V8.0 software
respectively.
Abstract: Value engineering is an efficacious contraption for
administrators to make up their minds. Value perusals proffer the
gaffers a suitable instrument to decrease the expenditures of the life
span, quality amelioration, structural improvement, curtailment of the
construction schedule, longevity prolongation or a merging of the
aforementioned cases. Subjecting organizers to pressures on one
hand and their accountability towards their pertinent fields together
with inherent risks and ambiguities of other options on the other hand
set some comptrollers in a dilemma utilization of risk management
and the value engineering in projects manipulation with regard to
complexities of implementing projects can be wielded as a
contraption to identify and efface each item which wreaks
unnecessary expenses and time squandering sans inflicting any
damages upon the essential project applications. Of course It should
be noted that implementation of risk management and value
engineering with regard to the betterment of efficiency and functions
may lead to the project implementation timing elongation. Here time
revamping does not refer to time diminishing in the whole cases. his
article deals with risk and value engineering conceptualizations at
first. The germane reverberations effectuated due to its execution in
Iran Khodro Corporation are regarded together with the joint features
and amalgamation of the aforesaid entia; hence the proposed
blueprint is submitted to be taken advantage of in engineering and
industrial projects including Iran Khodro Corporation.
Abstract: Text similarity measurement is a fundamental issue in
many textual applications such as document clustering, classification,
summarization and question answering. However, prevailing approaches
based on Vector Space Model (VSM) more or less suffer
from the limitation of Bag of Words (BOW), which ignores the semantic
relationship among words. Enriching document representation
with background knowledge from Wikipedia is proven to be an effective
way to solve this problem, but most existing methods still
cannot avoid similar flaws of BOW in a new vector space. In this
paper, we propose a novel text similarity measurement which goes
beyond VSM and can find semantic affinity between documents.
Specifically, it is a unified graph model that exploits Wikipedia as
background knowledge and synthesizes both document representation
and similarity computation. The experimental results on two different
datasets show that our approach significantly improves VSM-based
methods in both text clustering and classification.
Abstract: The morphological short-term evolution of Ponta do Tubarão Island (PTI) was investigated through high accurate surveys based on post-processed kinematic (PPK) relative positioning on Global Navigation Satellite Systems (GNSS). PTI is part of a barrier island system on a high energy northeast Brazilian coastal environment and also an area of high environmental sensitivity. Surveys were carried out quarterly over a two years period from May 2010 to May 2012. This paper assesses statically the performance of digital elevation models (DEM) derived from different interpolation methods to represent morphologic features and to quantify volumetric changes and TIN models shown the best results to that purposes. The MDE allowed quantifying surfaces and volumes in detail as well as identifying the most vulnerable segments of the PTI to erosion and/or accumulation of sediments and relate the alterations to climate conditions. The coastal setting and geometry of PTI protects a significant mangrove ecosystem and some oil and gas facilities installed in the vicinities from damaging effects of strong oceanwaves and currents. Thus, the maintenance of PTI is extremely required but the prediction of its longevity is uncertain because results indicate an irregularity of sedimentary balance and a substantial decline in sediment supply to this coastal area.
Abstract: Nowadays, financial and economic crises are growing
more and reach more countries and sectors. These events have, as a
result, a considerable impact on the activities of the firms which think
unstable and in danger.
But besides this heavy uncertainty which weighs on the different
firms, the family firm, object of our research, is not only confronted
with these external difficulties but also with an internal challenge and
of size: that of transmission. Indeed, the transmission of an
organization from one generation to another can succeed as it can
fail; leaving considerable damage.
Our research registers as part of these problems since we tried to
understand relation between the behavior of two main actors of the
process of succession, predecessor and successor; and the success of
transmission.
Abstract: Under the difficult access to finance of SMEs, they expect that its relationship with the banks shall constitute a real help to access appropriate financing, at reasonable costs and requirements, given the possibility of mutually beneficial and long lasting relation. The literature, but also the research we have carried on, is centered on such determinants as concentration and the length of the relationship, but at the same time, there is little certainty that banks are responding positively to them. Furthermore, although the trust is considered as being a fundamental element of bank relationship – see the case house bank – SMEs find that the banks finance them looking rather on collaterals and covenants than to trust. Moreover, a positive behavior, such as prompt or advance repayments of loans, doesn-t generate any positive feedback from the banks side. All these show a deep un-satisfaction of the SMEs concerning their relationship banking.
Abstract: Overloading is a technique to accommodate more
number of users than the spreading factor N. This is a bandwidth
efficient scheme to increase the number users in a fixed bandwidth.
One of the efficient schemes to overload a CDMA system is to use
two sets of orthogonal signal waveforms (O/O). The first set is
assigned to the N users and the second set is assigned to the
additional M users. An iterative interference cancellation technique is
used to cancel interference between the two sets of users. In this
paper, the performance of an overloading scheme in which the first N
users are assigned Walsh-Hadamard orthogonal codes and extra users
are assigned the same WH codes but overlaid by a fixed (quasi) bent
sequence [11] is evaluated. This particular scheme is called Quasi-
Orthogonal Sequence (QOS) O/O scheme, which is a part of
cdma2000 standard [12] to provide overloading in the downlink
using single user detector. QOS scheme are balance O/O scheme,
where the correlation between any set-1 and set-2 users are
equalized. The allowable overload of this scheme is investigated in
the uplink on an AWGN and Rayleigh fading channels, so that the
uncoded performance with iterative multistage interference
cancellation detector remains close to the single user bound. It is
shown that this scheme provides 19% and 11% overloading with
SDIC technique for N= 16 and 64 respectively, with an SNR
degradation of less than 0.35 dB as compared to single user bound at
a BER of 0.00001. But on a Rayleigh fading channel, the channel
overloading is 45% (29 extra users) at a BER of 0.0005, with an SNR
degradation of about 1 dB as compared to single user performance
for N=64. This is a significant amount of channel overloading on a
Rayleigh fading channel.
Abstract: This study examined the toxicological effects and
safety of polypeptide k isolated from the seeds of Momordica
charantia in laboratory rats. 30 male Sprague Dawley rats (12 weeks
old, bodyweight 180-200 g) were randomly divided into 3 groups
(1000 mg/kg, 500 mg and 0 mg/kg). Rats were acclimatized to
laboratory conditions for 7 days and at day 8 rats were dosed orally
with polypeptide k (in 2% DMSO/normal saline) and the controls
received the dosed vehicle only. Rats were then observed for 72
hours before sacrificed. Rats were anaesthetized by pentobarbital
(50 mg/kg ip) and 2-3.0 mL of blood was taken by cardiac puncture
and rats were scarified by anaesthetic overdose. Immediately, organs
(heart, lungs, liver, kidneys) were weigh and taken for histology.
Organ sections were then evaluated by a histopathologist. Serum
samples were assayed for liver functions (ALT and γ-GT) and kidney
functions (BUN and creatinine). All rats showed normal behavior
after the dosing and no statistical changes were observed in all blood
parameters and organ weight. Histological examinations revealed
normal organ structures. In conclusion, dosing of rats up to 1000
mg/kg did not have any effects on the rat behavior, liver or kidney
functions nor histology of the selected organs.
Abstract: Phytophthora cinnamomi (P. c) is a plant pathogenic
oomycete that is capable of damaging plants in commercial production
systems and natural ecosystems worldwide. The most common
methods for the detection and diagnosis of P. c infection are
expensive, elaborate and time consuming. This study was carried out
to examine whether species specific and life cycle specific volatile
organic compounds (VOCs) can be absorbed by solid-phase
microextraction fibers and detected by gas chromatography that are
produced by P. c and another oomycete Pythium dissotocum. A
headspace solid-phase microextraction (HS-SPME) together with gas
chromatography (GC) method was developed and optimized for the
identification of the VOCs released by P. c. The optimized parameters
included type of fiber, exposure time, desorption temperature and
desorption time. Optimization was achieved with the analytes of P.
c+V8A and V8A alone. To perform the HS-SPME, six types of fiber
were assayed and compared: 7μm Polydimethylsiloxane (PDMS),
100μm Polydimethylsiloxane (PDMS), 50/30μm
Divinylbenzene/CarboxenTM/Polydimethylsiloxane
DVB/CAR/PDMS), 65μm Polydimethylsiloxane/Divinylbenzene
(PDMS/DVB), 85μm Polyacrylate (PA) fibre and 85μm CarboxenTM/
Polydimethylsiloxane (Carboxen™/PDMS). In a comparison of the
efficacy of the fibers, the bipolar fiber DVB/CAR/PDMS had a higher
extraction efficiency than the other fibers. An exposure time of 16h
with DVB/CAR/PDMS fiber in the sample headspace was enough to
reach the maximum extraction efficiency. A desorption time of 3min
in the GC injector with the desorption temperature of 250°C was
enough for the fiber to desorb the compounds of interest. The chromatograms and morphology study confirmed that the VOCs from
P. c+V8A had distinct differences from V8A alone, as did different
life cycle stages of P. c and different taxa such as Pythium dissotocum.
The study proved that P. c has species and life cycle specific VOCs,
which in turn demonstrated the feasibility of this method as means of
Abstract: In This paper, the behavior of eccentric braced frame
(EBF) is studied with replacing friction damper (FD) in confluence of these braces, in 5 and 10-storey steel frames. For FD system, the main step is to determine the slip load. For this reason, the performance indexes include roof displacement, base shear, dissipated energy and relative performance should be investigated. In
nonlinear dynamic analysis, the response of structure to three
earthquake records has been obtained and the values of roof
displacement, base shear and column axial force for FD and EBF
frames have been compared. The results demonstrate that use of the FD in frames, in comparison with the EBF, substantially reduces the roof displacement, column axial force and base shear. The obtained results show suitable performance of FD in higher storey structure in
comparison with the EBF.
Abstract: The aim of this paper is to confirm the effect of key
design parameters, the punch radius and punch angle, on rupture of the
expansion tube using a finite element analysis with a ductile damage
model. The results of the finite element analysis indicated that the
expansion ratio of the tube was mainly affected by the radius of the
punch. However, the rupture was more affected by the punch angle
than the radius of the punch. The existence of a specific punch angle,
at which rupture did not occur, even if the radius of the punch was
increased, was found.
Abstract: Interpolated contour maps drawn for aluminum,
copper and molybdenum in downstream monitoring boreholes of
water dam in Miduk Copper Complex and the values of pH, redox
potential (Eh) and distance from water dam indicate different trends
of variation and behavior of these three elements in downward
groundwater resources. As these maps exhibit, aluminum is dominant
in the most alkaline (pH = 9-11) borehole (MB5) to water dam. The
highest concentration of molybdenum is found in the nearest
borehole (MB6) to water dam. Main concentration of copper is
observed in the most oxidized borehole (MB3 with Eh=293.2mV).
The spatial difference among sampling stations can be attributed to
the existence of faults and diaclases in the geologic structure of
Miduk region which causes the groundwater sampling sites to be
impressed by different contamination sources (toe seepage and upper
seepage water originated from different zones of tailings dump).
Abstract: This paper studies the problem of exponential
stability of perturbed discrete linear systems with periodic
coefficients. Assuming that the unperturbed system is exponentially
stable we obtain conditions on the perturbations under which the
perturbed system is exponentially stable.
Abstract: A nonlinear model of two-beam free-electron laser
(FEL) in the absence of slippage is presented. The two beams are
assumed to be cold with different energies and the fundamental
resonance of the higher energy beam is at the third harmonic of lower
energy beam. By using Maxwell-s equations and full Lorentz force
equations of motion for the electron beams, coupled differential
equations are derived and solved numerically by the fourth order
Runge–Kutta method. In this method a considerable growth of third
harmonic electromagnetic field in the XUV and X-ray regions is
predicted.
Abstract: In the current decade, wireless sensor networks are
emerging as a peculiar multi-disciplinary research area. By this
way, energy efficiency is one of the fundamental research themes
in the design of Medium Access Control (MAC) protocols for
wireless sensor networks. Thus, in order to optimize the energy
consumption in these networks, a variety of MAC protocols are
available in the literature. These schemes were commonly evaluated
under simple network density and a few results are published on
their robustness in realistic network-s size. We, in this paper, provide
an analytical study aiming to highlight the energy waste sources in
wireless sensor networks. Then, we experiment three energy efficient
hybrid CSMA/CA based MAC protocols optimized for wireless
sensor networks: Sensor-MAC (SMAC), Time-out MAC (TMAC)
and Traffic aware Energy Efficient MAC (TEEM). We investigate
these protocols with different network densities in order to discuss
the end-to-end performances of these schemes (i.e. in terms of energy
efficiency, delay and throughput). Through Network Simulator (NS-
2) implementations, we explore the behaviors of these protocols with
respect to the network density. In fact, this study may help the multihops
sensor networks designers to design or select the MAC layer
which matches better their applications aims.