Abstract: DC motors have been widely used in the past
centuries which are proudly known as the workhorse of industrial
systems until the invention of the AC induction motors which makes
a huge revolution in industries. Since then, the use of DC machines
has been decreased due to enormous factors such as reliability,
robustness and complexity but it lost its fame due to the losses. In this
paper a new methodology is proposed to construct a DC motor
through the simulation in LabVIEW to get an idea about its real time
performances, if a change in parameter might have bigger
improvement in losses and reliability.
Abstract: Proposed paper dealt with the modelling and analysis of induction motor based on the mathematical expression using the graphical programming environment of Laboratory Virtual Instrument Engineering Workbench (LabVIEW). Induction motor modelling with the mathematical expression enables the motor to be simulated with the various required parameters. Owing to the invention of variable speed drives study about the induction motor characteristics became complex. In this simulation motor internal parameter such as stator resistance and reactance, rotor resistance and reactance, phase voltage, frequency and losses will be given as input. By varying the speed of motor corresponding parameters can be obtained they are input power, output power, efficiency, torque induced, slip and current.
Abstract: Turkish migrants constitute the largest group among
people with migration background living in Germany. Turkish
women’s labor market participation is of significant importance for
their social and economic integration to the German society. This
paper thus aims to investigate their labor market positions. Turkish
migrant women participate less in the labor market compared to men,
and are responsible for most of the housework, child care, and elderly
care. This is due to their traditional roles in the family, educational
level, insufficient knowledge of German language, and insufficient
professional experience. We strongly recommend that wide-reaching
integration policies for women are formulated, so as to encourage
participation of not only migrant women but also their husbands,
fathers and/or brothers, and natives.
Abstract: The paper presents a method for a simple and
immediate motion planning of a SCARA robot, whose end-effector
has to move along a given trajectory; the calculation procedure
requires the user to define in analytical form or by points the
trajectory to be followed and to assign the curvilinear abscissa as
function of the time. On the basis of the geometrical characteristics
of the robot, a specifically developed program determines the motion
laws of the actuators that enable the robot to generate the required
movement; this software can be used in all industrial applications for
which a SCARA robot has to be frequently reprogrammed, in order
to generate various types of trajectories with different motion times.
Abstract: This study is about the structural transformations of
aluminium examining with the Dynamic Mechanical Thermal
Analyzer (DMTA). It is a faster and simpler measuring method to
make consequence about the metal’s structural transformations. The
device measures the changing of the mechanical characteristics
depending on the heating rate, and concludes certain transformations.
This measuring method fast and shows clean-cut results comparing
the conventional ways.
Applying polymer measuring devices for metal investigations is
not widespread method. One of the adaptable ways is shown in this
study. The article compares the results of the small specimen test and
the DMTA method, considering the temperature and the forming
dependence of recrystallization temperature.
Abstract: An Australian manufacturer has fabricated an
innovative GFRP sandwich panel made from E-glass fiber skin and a
modified phenolic core for structural applications. Debonding, which
refers to separation of skin from the core material in composite
sandwiches, is one of the most common types of damage in
composites. The presence of debonding is of great concern because it
not only severely affects the stiffness but also modifies the dynamic
behaviour of the structure. Generally it is seen that the majority of
research carried out has been concerned about the delamination of
laminated structures whereas skin-core debonding has received
relatively minor attention. Furthermore it is observed that research
done on composite slabs having multiple skin-core debonding is very
limited. To address this gap, a comprehensive research investigating
dynamic behaviour of composite panels with single and multiple
debonding is presented. The study uses finite-element modelling and
analyses for investigating the influence of debonding on free
vibration behaviour of single and multilayer composite sandwich
panels. A broad parametric investigation has been carried out by
varying debonding locations, debonding sizes and support conditions
of the panels in view of both single and multiple debonding.
Numerical models were developed with Strand7 finite element
package by innovatively selecting the suitable elements to diligently
represent their actual behavior. Three-dimensional finite element
models were employed to simulate the physically real situation as
close as possible, with the use of an experimentally and numerically
validated finite element model. Comparative results and conclusions
based on the analyses are presented. For similar extents and locations
of debonding, the effect of debonding on natural frequencies appears
greatly dependent on the end conditions of the panel, giving greater
decrease in natural frequency when the panels are more restrained.
Some modes are more sensitive to debonding and this sensitivity
seems to be related to their vibration mode shapes. The fundamental
mode seems generally the least sensitive mode to debonding with
respect to the variation in free vibration characteristics. The results
indicate the effectiveness of the developed three dimensional finite
element models in assessing debonding damage in composite
sandwich panels.
Abstract: Chrome tannery wastewater causes serious environmental hazard due to its high pollution potential. As a result, rigorous treatment is necessary for abatement of pollution from this type of wastewater. There are many research studies on chrome tannery wastewater treatment in the field of physical, chemical, and biological methods. In general, biological treatment process is found ineffective for direct application because of adverse effects by toxic chromium, sulphide, chloride etc. However, biological methods were employed mainly for a few sub processes generating significant amount of organic matter and without chromium, chlorides etc. In this context the present paper reviews the characteristics feature and pollution potential of wastewater generated from chrome tannery units and treatment of the same. The different biological processes used earlier and their chronological development for treatment of the chrome tannery wastewater are thoroughly reviewed in this paper. In this regard, the scope of hybrid bioreactor - an advanced technology option has also been explored, as this kind of treatment is well suited for the wastewater having inhibitory substances.
Abstract: This paper is focused on the CFD simulation of the radiaxial pump (i.e. mixed flow pump) with the aim to detect the reasons of Y-Q characteristic instability. The main reasons of pressure pulsations were detected by means of the analysis of velocity and pressure fields within the pump combined with the theoretical approach. Consequently, the modifications of spiral case and pump suction area were made based on the knowledge of flow conditions and the shape of dissipation function. The primary design of pump geometry was created as the base model serving for the comparison of individual modification influences. The basic experimental data are available for this geometry. This approach replaced the more complicated and with respect to convergence of all computational tasks more difficult calculation for the compressible liquid flow. The modification of primary pump consisted in inserting the three fins types. Subsequently, the evaluation of pressure pulsations, specific energy curves and visualization of velocity fields were chosen as the criterion for successful design.
Abstract: The article deals with the tool in Matlab GUI form
that is designed to analyse a mechatronic system sensitivity and
tolerance. In the analysed mechatronic system, a torque is transferred
from the drive to the load through a coupling containing flexible
elements. Different methods of control system design are used. The
classic form of the feedback control is proposed using Naslin method,
modulus optimum criterion and inverse dynamics method. The
cascade form of the control is proposed based on combination of
modulus optimum criterion and symmetric optimum criterion. The
sensitivity is analysed on the basis of absolute and relative sensitivity
of system function to the change of chosen parameter value of the
mechatronic system, as well as the control subsystem. The tolerance
is analysed in the form of determining the range of allowed relative
changes of selected system parameters in the field of system stability.
The tool allows to analyse an influence of torsion stiffness, torsion
damping, inertia moments of the motor and the load and controller(s)
parameters. The sensitivity and tolerance are monitored in terms of
the impact of parameter change on the response in the form of system
step response and system frequency-response logarithmic
characteristics. The Symbolic Math Toolbox for expression of the
final shape of analysed system functions was used. The sensitivity
and tolerance are graphically represented as 2D graph of sensitivity
or tolerance of the system function and 3D/2D static/interactive graph
of step/frequency response.
Abstract: The present work attempts to investigate the
combustion, performance and emission characteristics of an existing
single-cylinder four-stroke compression-ignition engine operated in
dual-fuel mode with hydrogen as an alternative fuel. Environmental
concerns and limited amount of petroleum fuels have caused interests
in the development of alternative fuels like hydrogen for internal
combustion (IC) engines. In this experimental investigation, a diesel
engine is made to run using hydrogen in dual fuel mode with diesel,
where hydrogen is introduced into the intake manifold using an LPGCNG
injector and pilot diesel is injected using diesel injectors. A
Timed Manifold Injection (TMI) system has been developed to vary
the injection strategies. The optimized timing for the injection of
hydrogen was 10^0 CA after top dead center (ATDC). From the study
it was observed that with increasing hydrogen rate, enhancement in
brake thermal efficiency (BTHE) of the engine has been observed
with reduction in brake specific energy consumption (BSEC).
Furthermore, Soot contents decrease with an increase in indicated
specific NOx emissions with the enhancement of hydrogen flow rate.
Abstract: This paper deals with the theoretical and numerical
investigation of magneto hydrodynamic boundary layer flow of a
nanofluid past a wedge shaped wick in heat pipe used for the cooling
of electronic components and different type of machines. To
incorporate the effect of nanoparticle diameter, concentration of
nanoparticles in the pure fluid, nanothermal layer formed around the
nanoparticle and Brownian motion of nanoparticles etc., appropriate
models are used for the effective thermal and physical properties of
nanofluids. To model the rotation of nanoparticles inside the base
fluid, microfluidics theory is used. In this investigation ethylene
glycol (EG) based nanofluids, are taken into account. The non-linear
equations governing the flow and heat transfer are solved by using a
very effective particle swarm optimization technique along with
Runge-Kutta method. The values of heat transfer coefficient are
found for different parameters involved in the formulation viz.
nanoparticle concentration, nanoparticle size, magnetic field and
wedge angle etc. It is found that, the wedge angle, presence of
magnetic field, nanoparticle size and nanoparticle concentration etc.
have prominent effects on fluid flow and heat transfer characteristics
for the considered configuration.
Abstract: We investigate relaxation dynamics of a quantum
dipole emitter (QDE), e.g., a molecule or quantum dot, located near a
metal nanoparticle (MNP) exhibiting a dipolar localized surface
plasmon (LSP) resonance at the frequency of the QDE radiative
transition. It is shown that under the condition of the QDE-MNP
characteristic relaxation time being much shorter than that of the
QDE in free-space but much longer than the LSP lifetime. It is also
shown that energy dissipation in the QDE-MNP system is relatively
weak with the probability of the photon emission being about 0.75, a
number which, rather surprisingly, does not explicitly depend on the
metal absorption characteristics. The degree of entanglement
measured by the concurrency takes the maximum value, while the
distances between the QDEs and metal ball approximately are equal.
Abstract: Early diagnosis of infection like Hep-B virus in blood
is important for low cost medical treatment. For this purpose, it is
desirable to develop a point of care device which should be able to
detect trace quantities of the target molecule in blood. In this paper,
we report a nanoporous silicon oxide sensor which is capable of
detecting down to 1fM concentration of Hep-B surface antigen in
blood without the requirement of any centrifuge or pre-concentration.
This has been made possible by the presence of resonant peak in the
sensitivity characteristics. This peak is observed to be dependent only
on the concentration of the specific antigen and not on the interfering
species in blood serum. The occurrence of opposite impedance
change within the pores and at the bottom of the pore is responsible
for this effect. An electronic interface has also been designed to
provide a display of the virus concentration.
Abstract: Typically, virtual communities exhibit the well-known
phenomenon of participation inequality, which means that only a
small percentage of users is responsible of the majority of
contributions. However, the sustainability of the community requires
that the group of active users must be continuously nurtured with new
users that gain expertise through a participation process. This paper
analyzes the time evolution of Open Source Software (OSS)
communities, considering users that join/abandon the community
over time and several topological properties of the network when
modeled as a social network. More specifically, the paper analyzes
the role of those users rejoining the community and their influence in
the global characteristics of the network.
Abstract: In this paper, the effects of fiber types and elevated
temperatures on compressive strength, modulus of rapture and the
bond characteristics of fiber reinforced concretes (FRC) are
presented. By using the three different types of fibers (steel fiber-SF,
polypropylene-PPF and polyvinyl alcohol-PVA), FRC specimens
were produced and exposed to elevated temperatures up to 800 ºC for
1.5 hours. In addition, a plain concrete (without fiber) was produced
and used as a control. Test results obtained showed that the steel fiber
reinforced concrete (SFRC) had the highest compressive strength,
modulus of rapture and bond stress values at room temperatures, the
residual bond, flexural and compressive strengths of both FRC and
plain concrete dropped sharply after exposure to high temperatures.
The results also indicated that the reduction of bond, flexural and
compressive strengths with increasing the exposed temperature was
relatively less for SFRC than for plain, and FRC with PPF and PVA.
Abstract: Experimental study of natural convection heat transfer
inside smooth and rough surfaces of vertical and inclined equilateral
triangular channels of different inclination angles with a uniformly
heated surface are performed. The inclination angle is changed from
15º to 90º. Smooth and rough surface of average roughness (0.02mm)
are used and their effect on the heat transfer characteristics are
studied. The local and average heat transfer coefficients and Nusselt
number are obtained for smooth and rough channels at different heat
flux values, different inclination angles and different Rayleigh
numbers (Ra) 6.48 × 105 ≤ Ra ≤ 4.78 × 106. The results show that
the local Nusselt number decreases with increase of axial distance
from the lower end of the triangular channel to a point near the upper
end of channel, and then, it slightly increases. Higher values of local
Nusselt number for rough channel along the axial distance compared
with the smooth channel. The average Nusselt number of rough
channel is higher than that of smooth channel by about 8.1% for
inclined case at θ = 45o and 10% for vertical case. The results
obtained are correlated using dimensionless groups for both rough
and smooth surfaces of the inclined and vertical triangular channels.
Abstract: This article discusses event monitoring options for
heterogeneous event sources as they are given in nowadays
heterogeneous distributed information systems. It follows the central
assumption, that a fully generic event monitoring solution cannot
provide complete support for event monitoring; instead, event source
specific semantics such as certain event types or support for certain
event monitoring techniques have to be taken into account.
Following from this, the core result of the work presented here is
the extension of a configurable event monitoring (Web) service for a
variety of event sources. A service approach allows us to trade
genericity for the exploitation of source specific characteristics. It
thus delivers results for the areas of SOA, Web services, CEP and
EDA.
Abstract: The hydrodynamics and heat transfer characteristics
of a vaporized elongated bubble in a rectangular microchannel have
been simulated based on Cahn-Hilliard phase-field method. In the
simulations, the initially nucleated bubble starts growing as it comes
in contact with superheated water. The growing shape of the bubble
compared well with the available experimental data in the literature.
Abstract: Fixed-geometry hydrodynamic journal bearings are
one of the best supporting systems for several applications of rotating
machinery. Cylindrical journal bearings present excellent loadcarrying
capacity and low manufacturing costs, but they are subjected
to the oil-film instability at high speeds. An attempt of overcoming
this instability problem has been the development of non-circular
journal bearings. This work deals with an analysis of oil-lubricated
elliptical journal bearings using the finite element method. Steadystate
and dynamic performance characteristics of elliptical bearings
are rendered by zeroth- and first-order lubrication equations obtained
through a linearized perturbation method applied on the classical
Reynolds equation. Four-node isoparametric rectangular finite
elements are employed to model the bearing thin film flow. Curves of
elliptical bearing load capacity and dynamic force coefficients are
rendered at several operating conditions. The results presented in this
work demonstrate the influence of the bearing ellipticity on its
performance at different loading conditions.
Abstract: In this study, a computational fluid dynamics (CFD)
model has been developed for studying the effect of surface
roughness profile on the EHL problem. The cylinders contact
geometry, meshing and calculation of the conservation of mass and
momentum equations are carried out using the commercial software
packages ICEMCFD and ANSYS Fluent. The user defined functions
(UDFs) for density, viscosity and elastic deformation of the cylinders
as the functions of pressure and temperature are defined for the CFD
model. Three different surface roughness profiles are created and
incorporated into the CFD model. It is found that the developed CFD
model can predict the characteristics of fluid flow and heat transfer in
the EHL problem, including the main parameters such as pressure
distribution, minimal film thickness, viscosity, and density changes.
The results obtained show that the pressure profile at the center of the
contact area directly relates to the roughness amplitude. A rough
surface with kurtosis value of more than 3 has greater influence over
the fluctuated shape of pressure distribution than in other cases.