Abstract: Spectrum sensing is the main feature of cognitive
radio technology. Spectrum sensing gives an idea of detecting the
presence of the primary users in a licensed spectrum. In this paper we
compare the theoretical results of detection probability of different
fading environments like Rayleigh, Rician, Nakagami-m fading
channels with the simulation results using energy detection based
spectrum sensing. The numerical results are plotted as Pf Vs Pd for
different SNR values, fading parameters. It is observed that
Nakagami fading channel performance is better than other fading
channels by using energy detection in spectrum sensing. A MATLAB
simulation test bench has been implemented to know the performance
of energy detection in different fading channel environment.
Abstract: This article presents a new vibration diagnostic
method designed to (PM) machines with permanent magnets. Those
devices are commonly used in small wind and water systems or
vehicles drives. The author’s method is very innovative and unique.
Specific structural properties of PM machines are used in this method
- electromotive force (EMF) generated due to vibrations. There was
analysed number of publications which describe vibration diagnostic
methods and tests of electrical PM machines and there was no
method found to determine the technical condition of such machine
basing on their own signals. In this article will be discussed: the
method genesis, the similarity of machines with permanent magnet to
vibration sensor and simulation and laboratory tests results. The
method of determination the technical condition of electrical machine
with permanent magnets basing on its own signals is the subject of
patent application and it is the main thesis of author’s doctoral
dissertation.
Abstract: This research focuses on the optimization of glazed
surfaces and the assessment of possible solar gains in industrial
buildings. Existing window rating methods for single windows were
evaluated and a new method for a simple analysis of energy gains and
losses by single windows was introduced. Furthermore extensive
transient building simulations were carried out to appraise the
performance of low cost polycarbonate multi-cell sheets in
interaction with typical buildings for industrial applications. Mainly
energy saving potential was determined by optimizing the orientation
and area of such glazing systems in dependency on their thermal
qualities. Moreover the impact on critical aspects such as summer
overheating and daylight illumination was considered to ensure the
user comfort and avoid additional energy demand for lighting or
cooling. Hereby the simulated heating demand could be reduced by
up to 1/3 compared to traditional architecture of industrial halls using
mainly skylights.
Abstract: Different order modulations combined with different
coding schemes, allow sending more bits per symbol, thus achieving
higher throughputs and better spectral efficiencies. However, it must
also be noted that when using a modulation technique such as 64-
QAM with less overhead bits, better signal-to-noise ratios (SNRs) are
needed to overcome any Inter symbol Interference (ISI) and maintain
a certain bit error ratio (BER). The use of adaptive modulation allows
wireless technologies to yielding higher throughputs while also
covering long distances. The aim of this paper is to implement an
Adaptive Modulation and Coding (AMC) features of the WiMAX
PHY in MATLAB and to analyze the performance of the system in
different channel conditions (AWGN, Rayleigh and Rician fading
channel) with channel estimation and blind equalization. Simulation
results have demonstrated that the increment in modulation order
causes to increment in throughput and BER values. These results
derived a trade-off among modulation order, FFT length, throughput,
BER value and spectral efficiency. The BER changes gradually for
AWGN channel and arbitrarily for Rayleigh and Rician fade
channels.
Abstract: This paper presents a new method to design nonlinear
feedback linearization controller for PEMFCs (Polymer Electrolyte
Membrane Fuel Cells). A nonlinear controller is designed based on
nonlinear model to prolong the stack life of PEMFCs. Since it is
known that large deviations between hydrogen and oxygen partial
pressures can cause severe membrane damage in the fuel cell,
feedback linearization is applied to the PEMFC system so that the
deviation can be kept as small as possible during disturbances or load
variations. To obtain an accurate feedback linearization controller,
tuning the linear parameters are always important. So in proposed
study NSGA (Non-Dominated Sorting Genetic Algorithm)-II method
was used to tune the designed controller in aim to decrease the
controller tracking error. The simulation result showed that the
proposed method tuned the controller efficiently.
Abstract: This paper presents a hybrid three phase rectifier for
high power factor application. This rectifier is composed by zero
voltage transition (ZVT) and zero current transition (ZCT) boost
converter with three phase diode bridge rectifier, in parallel with a six
pulse three phase pulse width modulation (PWM) controlled rectifier.
The proposed topology is capable of high power factor with DC
output voltage regulation by providing sinusoidal input. Also, it
increases the overall efficiency of the new hybrid rectifier to 94.56%
and the total harmonic distortion of the hybrid structure varies from
0% to 16% at nominal output power. This topology was simulated in
MATLAB/SIMULINK environment and the output waveforms
presented with experimental result.
Abstract: Diabetes is a growing health problem in worldwide.
Especially, the patients with Type 1 diabetes need strict glycemic
control because they have deficiency of insulin production. This
paper attempts to control blood glucose based on body mathematical
body model. The Bergman minimal mathematical model is used to
develop the nonlinear controller. A novel back-stepping based sliding
mode control (B-SMC) strategy is proposed as a solution that
guarantees practical tracking of a desired glucose concentration. In
order to show the performance of the proposed design, it is compared
with conventional linear and fuzzy controllers which have been done
in previous researches. The numerical simulation result shows the
advantages of sliding mode back stepping controller design to linear
and fuzzy controllers.
Abstract: This paper presents an anthropometric study
conducted to 300 employees in a maquiladora industry that belongs
to the cluster of medical products as part of a research project to
pretend simulate workplace conditions under which operators
conduct their activities. This project is relevant because traditionally
performed a study to design ergonomic workspaces according to
anthropometric profile of users, however, this paper demonstrates the
importance of making decisions when the infrastructure cannot be
adapted for economic whichever put emphasis on user activity.
Abstract: A circularly polarized fractal boundary microstrip
antenna is presented. The sides of a square patch along x- axis, yaxis
are replaced with Minkowski and Koch curves correspondingly.
By using the fractal curves as edges, asymmetry in the structure is
created to excite two orthogonal modes for circular polarization (CP)
operation. The indentation factors of the fractal curves are optimized
for pure CP. The simulated results of the novel polyfractal antenna
are demonstrated.
Abstract: Load carrying capacity of an oil lubricated two-axial
groove journal bearing is simulated by taking into account the
viscosity variations in lubricant due to the addition of TiO2
nanoparticles as lubricant additive. Shear viscosities of TiO2
nanoparticle dispersions in oil are measured for various nanoparticle
additive concentrations. The viscosity model derived from the
experimental viscosities is employed in a modified Reynolds
equation to obtain the pressure profiles and load carrying capacity of
two-axial groove journal bearing. Results reveal an increase in load
carrying capacity of bearings operating on nanoparticle dispersions as
compared to plain oil.
Abstract: This study focuses on the cooling of a photovoltaic
panel (PV). Indeed, the cooling improves the conversion capacity of
this one and maintains, under extreme conditions of air temperature,
the panel temperature at an appreciable level which avoids the
altering. To do this, a fan provides forced circulation of air. Because
the fan is supplied by the panel, it is necessary to determine the
optimum operating point that unites efficiency of the PV with the
consumption of the fan. For this matter, numerical simulations are
performed at varying mass flow rates of air, under two extreme air
temperatures (50°C, 25°C) and a fixed solar radiation (1000W.m2) in
a case of no wind.
Abstract: The study deals with the challenges in developing a
test rig to test the performance of water lubricated journal bearing.
The test rig is designed to simulate the working conditions of the
bearing in order to understand their performance before they are put
in operation. The bearing that is studied is the commercially available
water lubricated bearing which has a rubber liner bonded with a rigid
metal shell. The lubricant enters the bearing axially through a
pressurized inlet tank and exits to an outlet tank which is at
sufficiently low pressure. The load on the bearing is applied through
the dead weight system which acts both in upward and downward
direction so that net load acts on the bearing. The issues in feeding
the lubricant into the bearing from the inlet side and preventing the
leakage of the lubricant is discussed. The application of the load on
the test bearing while maintaining the bearing afloat is also discussed.
Abstract: The Sigma-Delta A/D converters have been proposed
as a practical application for A/D conversion at high rates because of
its simplicity and robustness to imperfections in the circuit, also
because the traditional converters are more difficult to implement in
VLSI technology. These difficulties with conventional conversion
methods need precise analog components in their filters and
conversion circuits, and are more vulnerable to noise and
interference. This paper aims to analyze the architecture, function and
application of Analog-Digital converters (A/D) Sigma-Delta to
overcome these difficulties, showing some simulations using the
Simulink software and Multisim.
Abstract: This paper deals with a simulation programs and
technologies using in the educational process for members of the crisis
management. Risk analysis, simulation, preparation and planning are
among the main activities of workers of crisis management. Made
correctly simulation of emergency defines the extent of the danger. On
this basis, it is possible to effectively prepare and plan measures to
minimize damage. The paper is focused on simulation programs that
are trained at the University of Defence. Implementation of the outputs
from simulation programs in decision-making processes of crisis staffs
is one of the main tasks of the research project.
Abstract: In this study, a three dimensional numerical heat
transfer model has been used to simulate the laser structuring of
polymer substrate material in the Three-Dimensional Molded
Interconnect Device (3D MID) which is used in the advanced multifunctional
applications. A finite element method (FEM) transient
thermal analysis is performed using APDL (ANSYS Parametric
Design Language) provided by ANSYS. In this model, the effect of
surface heat source was modeled with Gaussian distribution, also the
effect of the mixed boundary conditions which consist of convection
and radiation heat transfers have been considered in this analysis. The
model provides a full description of the temperature distribution, as
well as calculates the depth and the width of the groove upon material
removal at different set of laser parameters such as laser power and
laser speed. This study also includes the experimental procedure to
study the effect of laser parameters on the depth and width of the
removal groove metal as verification to the modeled results. Good
agreement between the experimental and the model results is
achieved for a wide range of laser powers. It is found that the quality
of the laser structure process is affected by the laser scan speed and
laser power. For a high laser structured quality, it is suggested to use
laser with high speed and moderate to high laser power.
Abstract: Estimation of a proportion has many applications in
economics and social studies. A common application is the estimation
of the low income proportion, which gives the proportion of people
classified as poor into a population. In this paper, we present this
poverty indicator and propose to use the logistic regression estimator
for the problem of estimating the low income proportion. Various
sampling designs are presented. Assuming a real data set obtained
from the European Survey on Income and Living Conditions, Monte
Carlo simulation studies are carried out to analyze the empirical
performance of the logistic regression estimator under the various
sampling designs considered in this paper. Results derived from
Monte Carlo simulation studies indicate that the logistic regression
estimator can be more accurate than the customary estimator under
the various sampling designs considered in this paper. The stratified
sampling design can also provide more accurate results.
Abstract: Voltage sags are the most common power quality
disturbance in the distribution system. It occurs due to the fault in the
electrical network or by the starting of a large induction motor and
this can be solved by using the custom power devices such as
Dynamic Voltage Restorer (DVR). In this paper DVR is proposed to
compensate voltage sags on critical loads dynamically. The DVR
consists of VSC, injection transformers, passive filters and energy
storage (lead acid battery). By injecting an appropriate voltage, the
DVR restores a voltage waveform and ensures constant load voltage.
The simulation and experimental results of a DVR using MATLAB
software shows clearly the performance of the DVR in mitigating
voltage sags.
Abstract: The most important part of modern lean low NOx combustors is a premixer where swirlers are often used for intensification of mixing processes and further formation of required flow pattern in combustor liner. Swirling flow leads to formation of complex eddy structures causing flow perturbations. It is able to cause combustion instability. Therefore, at design phase, it is necessary to pay great attention to aerodynamics of premixers. Analysis based on unsteady CFD modeling of swirling flow in production combustor swirler showed presence of large number of different eddy structures that can be conditionally divided into three types relative to its location of origin and a propagation path. Further, features of each eddy type were subsequently defined. Comparison of calculated and experimental pressure fluctuations spectrums verified correctness of computations.
Abstract: This paper presents a 3D guidance scheme for
Unmanned Aerial Vehicles (UAVs). The proposed guidance scheme
is based on the sliding mode approach using nonlinear sliding
manifolds. Generalized 3D kinematic equations are considered
here during the design process to cater for the coupling between
longitudinal and lateral motions. Sliding mode based guidance
scheme is then derived for the multiple-input multiple-output
(MIMO) system using the proposed nonlinear manifolds. Instead of
traditional sliding surfaces, nonlinear sliding surfaces are proposed
here for performance and stability in all flight conditions. In the
reaching phase control inputs, the bang-bang terms with signum
functions are accompanied with proportional terms in order to reduce
the chattering amplitudes. The Proposed 3D guidance scheme is
implemented on a 6-degrees-of-freedom (6-dof) simulation of a UAV
and simulation results are presented here for different 3D trajectories
with and without disturbances.
Abstract: During welding, the amount of heat present in weld
zones determines the quality of weldment produced. Thus, the heat
distribution characteristics and its magnitude in weld zones with
respect to process variables such as tool pin-shoulder rotational and
traveling speed during welding is analyzed using thermal finite
element analyses method. For this purpose, transient thermal finite
element analyses are performed to model the temperatures
distribution and its quantities in weld-zones with respect to process
variables such as rotational speed and traveling speed during welding.
Commercially available software Altair HyperWork is used to model
three-dimensional tool pin-shoulder vs. workpieces and to simulate
the friction stir process. The results show that increasing tool
rotational speed, at a constant traveling speed, will increase the
amount of heat generated in weld-zones. In contrary, increasing
traveling speed, at constant tool pin-shoulder rotational speeds, will
reduce the amount of heat generated in weld zones.