Abstract: In recent years Malaysia has included renewable
energy as an alternative fuel to help in diversifying the country-s
energy reliance on oil, natural gas, coal and hydropower with
biomass and solar energy gaining priority. The scope of this paper is
to look at the designing procedures and analysis of a solar thermal
parabolic trough concentrator by simulation utilizing meteorological
data in several parts of Malaysia. Parameters which include the
aperture area, the diameter of the receiver and the working fluid may
be varied to optimize the design. Aperture area is determined by
considering the width and the length of the concentrator whereas the
geometric concentration ratio (CR) is obtained by considering the
width and diameter of the receiver. Three types of working fluid are
investigated. Theoretically, concentration ratios can be very high in
the range of 10 to 40 000 depending on the optical elements used and
continuous tracking of the sun. However, a thorough analysis is
essential as discussed in this paper where optical precision and
thermal analysis must be carried out to evaluate the performance of
the parabolic trough concentrator as the theoretical CR is not the only
factor that should be considered.
Abstract: Induction motors are being used in greater numbers
throughout a wide variety of industrial and commercial applications
because it provides many benefits and reliable device to convert the
electrical energy into mechanical motion. In some application it-s
desired to control the speed of the induction motor. Because of the
physics of the induction motor the preferred method of controlling its
speed is to vary the frequency of the AC voltage driving the motor. In
recent years, with the microcontroller incorporated into an appliance
it becomes possible to use it to generate the variable frequency AC
voltage to control the speed of the induction motor.
This study investigates the microcontroller based variable
frequency power inverter. the microcontroller is provide the variable
frequency pulse width modulation (PWM) signal that control the
applied voltage on the gate drive, which is provides the required
PWM frequency with less harmonics at the output of the power
inverter.
The fully controlled bridge voltage source inverter has been
implemented with semiconductors power devices isolated gate
bipolar transistor (IGBT), and the PWM technique has been
employed in this inverter to supply the motor with AC voltage.
The proposed drive system for three & single phase power inverter
is simulated using Matlab/Simulink. The Matlab Simulation Results
for the proposed system were achieved with different SPWM. From
the result a stable variable frequency inverter over wide range has
been obtained and a good agreement has been found between the
simulation and hardware of a microcontroller based single phase
inverter.
Abstract: The main objectif of this paper is to present a tool that
we have developed subject to characterize and modelling indoor radio
channel propagation at millimetric wave. The tool is based on the
ray tracing technique (RTT). As, in realistic environment we cannot
neglect the significant impact of Human Body Shadowing and other
objects in motion on indoor 60 GHz propagation channel. Hence,
our proposed model allows a simulation of propagation in a dynamic
indoor environment. First, we describe a model of human body.
Second, RTT with this model is used to simulate the propagation
of millimeter waves in the presence of persons in motion. Results
of the simulation show that this tool gives results in agreement with
those reported in the literature. Specially, the effects of people motion
on temporal channel properties.
Abstract: An original Direct Numerical Simulation (DNS) method to tackle the problem of particulate flows at moderate to high concentration and finite Reynolds number is presented. Our method is built on the framework established by Glowinski and his coworkers [1] in the sense that we use their Distributed Lagrange Multiplier/Fictitious Domain (DLM/FD) formulation and their operator-splitting idea but differs in the treatment of particle collisions. The novelty of our contribution relies on replacing the simple artificial repulsive force based collision model usually employed in the literature by an efficient Discrete Element Method (DEM) granular solver. The use of our DEM solver enables us to consider particles of arbitrary shape (at least convex) and to account for actual contacts, in the sense that particles actually touch each other, in contrast with the simple repulsive force based collision model. We recently upgraded our serial code, GRIFF 1 [2], to full MPI capabilities. Our new code, PeliGRIFF 2, is developed under the framework of the full MPI open source platform PELICANS [3]. The new MPI capabilities of PeliGRIFF open new perspectives in the study of particulate flows and significantly increase the number of particles that can be considered in a full DNS approach: O(100000) in 2D and O(10000) in 3D. Results on the 2D/3D sedimentation/fluidization of isometric polygonal/polyedral particles with collisions are presented.
Abstract: The parametrical study of Shrouded Contra-rotating
Rotor was done in this paper based on 2D axisymmetric simulations.
The calculations were made with an actuator disk as double rotor
model. It objects to explore and quantify the effects of different shroud
geometry parameters mainly using the performance of power loading
(PL), which could evaluate the whole propulsion system capability as
5 Newtontotal thrust generationfor hover demand. The numerical
results show that:The increase of nozzle radius is desired but limited
by the flow separation, its optimal design is around 1.15 times rotor
radius, the viscosity effects greatly constraint the influence of nozzle
shape, the divergent angle around 10.5° performs best for chosen
nozzle length;The parameters of inlet such as leading edge curvature,
radius and internal shape do not affect thrust great but play an
important role in pressure distribution which could produce most part
of shroud thrust, they should be chosen according to the reduction of
adverse pressure gradients to reduce the risk of boundary separation.
Abstract: This paper describes a steady state model of a multiple
effect evaporator system for simulation and control purposes. The
model includes overall as well as component mass balance equations,
energy balance equations and heat transfer rate equations for area
calculations for all the effects. Each effect in the process is
represented by a number of variables which are related by the energy
and material balance equations for the feed, product and vapor flow
for backward, mixed and split feed. For simulation 'fsolve' solver in
MATLAB source code is used. The optimality of three sequences i.e.
backward, mixed and splitting feed is studied by varying the various
input parameters.
Abstract: The Influence Diagrams (IDs) is a kind of Probabilistic Belief Networks for graphic modeling. The usage of IDs can improve the communication among field experts, modelers, and decision makers, by showing the issue frame discussed from a high-level point of view. This paper enhances the Time-Sliced Influence Diagrams (TSIDs, or called Dynamic IDs) based formalism from a Discrete Event Systems Modeling and Simulation (DES M&S) perspective, for Exploring Analysis (EA) modeling. The enhancements enable a modeler to specify times occurred of endogenous events dynamically with stochastic sampling as model running and to describe the inter- influences among them with variable nodes in a dynamic situation that the existing TSIDs fails to capture. The new class of model is named Dynamic-Stochastic Influence Diagrams (DSIDs). The paper includes a description of the modeling formalism and the hiberarchy simulators implementing its simulation algorithm, and shows a case study to illustrate its enhancements.
Abstract: This article proposes a voltage-mode
multifunction filter using differential voltage current
controllable current conveyor transconductance amplifier
(DV-CCCCTA). The features of the circuit are that: the
quality factor and pole frequency can be tuned independently
via the values of capacitors: the circuit description is very
simple, consisting of merely 1 DV-CCCCTA, and 2
capacitors. Without any component matching conditions, the
proposed circuit is very appropriate to further develop into
an integrated circuit. Additionally, each function response
can be selected by suitably selecting input signals with
digital method. The PSpice simulation results are depicted.
The given results agree well with the theoretical anticipation.
Abstract: The dynamic spectrum allocation solutions such as
cognitive radio networks have been proposed as a key technology to
exploit the frequency segments that are spectrally underutilized.
Cognitive radio users work as secondary users who need to
constantly and rapidly sense the presence of primary users or
licensees to utilize their frequency bands if they are inactive. Short
sensing cycles should be run by the secondary users to achieve
higher throughput rates as well as to provide low level of interference
to the primary users by immediately vacating their channels once
they have been detected. In this paper, the throughput-sensing time
relationship in local and cooperative spectrum sensing has been
investigated under two distinct scenarios, namely, constant primary
user protection (CPUP) and constant secondary user spectrum
usability (CSUSU) scenarios. The simulation results show that the
design of sensing slot duration is very critical and depends on the
number of cooperating users under CPUP scenario whereas under
CSUSU, cooperating more users has no effect if the sensing time
used exceeds 5% of the total frame duration.
Abstract: In this paper, we propose ablock-wise watermarking scheme for color image authentication to resist malicious tampering of digital media. The thresholding technique is incorporated into the scheme such that the tampered region of the color image can be recovered with high quality while the proofing result is obtained. The watermark for each block consists of its dual authentication data and the corresponding feature information. The feature information for recovery iscomputed bythe thresholding technique. In the proofing process, we propose a dual-option parity check method to proof the validity of image blocks. In the recovery process, the feature information of each block embedded into the color image is rebuilt for high quality recovery. The simulation results show that the proposed watermarking scheme can effectively proof the tempered region with high detection rate and can recover the tempered region with high quality.
Abstract: In this research, heat transfer of a poly Ethylene
fluidized bed reactor without reaction were studied experimentally
and computationally at different superficial gas velocities. A multifluid
Eulerian computational model incorporating the kinetic theory
for solid particles was developed and used to simulate the heat
conducting gas–solid flows in a fluidized bed configuration.
Momentum exchange coefficients were evaluated using the Syamlal–
O-Brien drag functions. Temperature distributions of different phases
in the reactor were also computed. Good agreement was found
between the model predictions and the experimentally obtained data
for the bed expansion ratio as well as the qualitative gas–solid flow
patterns. The simulation and experimental results showed that the gas
temperature decreases as it moves upward in the reactor, while the
solid particle temperature increases. Pressure drop and temperature
distribution predicted by the simulations were in good agreement
with the experimental measurements at superficial gas velocities
higher than the minimum fluidization velocity. Also, the predicted
time-average local voidage profiles were in reasonable agreement
with the experimental results. The study showed that the
computational model was capable of predicting the heat transfer and
the hydrodynamic behavior of gas-solid fluidized bed flows with
reasonable accuracy.
Abstract: The objectif of the present work is to determinate the
potential of the solar parabolic trough collector (PTC) for use in the
design of a solar thermal power plant in Algeria. The study is based
on a mathematical modeling of the PTC. Heat balance has been
established respectively on the heat transfer fluid (HTF), the absorber
tube and the glass envelop using the principle of energy conservation
at each surface of the HCE cross-sectionn. The modified Euler
method is used to solve the obtained differential equations. At first
the results for typical days of two seasons the thermal behavior of the
HTF, the absorber and the envelope are obtained. Then to determine
the thermal performances of the heat transfer fluid, different oils are
considered and their temperature and heat gain evolutions compared.
Abstract: An experimental and simulation flight test has been carried out to evaluate the longitudinal gliding characteristics of a lifting body with blunted half-cone geometry. The novelty here is the lifting body's pitch control mechanism, which consists of a pair of leading-edge rotating cylinders. Flight simulation uses aerodynamic data from computational fluid dynamics supported by wind-tunnel test. Flight test consists of releasing an aluminum lifting body model from a moving vehicle at the appropriate wind speed while measuring the lifting body's variation of altitude against time of flight. Results show that leading-edge rotating cylinder is able to give small amounts of improvement to the longitudinal stability and pitch control to the lifting body.
Abstract: Fuel cell's system requires regulating circuit for
voltage and current in order to control power in case of connecting to
other generative devices or load. In this paper Fuel cell system and
convertor, which is a multi-variable system, are controlled using
sliding mode method. Use of weighting matrix in design procedure
made it possible to regulate speed of control. Simulation results show
the robustness and accuracy of proposed controller for controlling
desired of outputs.
Abstract: This paper addresses the problem of blind source separation
(BSS). To recover original signals, from linear instantaneous
mixtures, we propose a new contrast function based on the use of a
double referenced system. Our approach assumes statistical independence
sources. The reference vectors will be incrusted in the cumulant
to evaluate the independence. The estimation of the separating matrix
will be performed in two steps: whitening observations and joint
diagonalization of a set of referenced cumulant matrices. Computer
simulations are presented to demonstrate the effectiveness of the
suggested approach.
Abstract: In recent years, sustainable supply chain management
(SSCM) has been widely researched in academic domain. However,
due to the traditional operational role and the complexity of supply
chain management in the cement industry, a relatively small amount
of research has been conducted on cement supply chain simulation
integrated with sustainability criteria. This paper analyses the cement
supply chain operations using the Push-Pull supply chain
frameworks, the Life Cycle Assessment (LCA) methodology; and
proposal integration approach, proposes three supply chain scenarios
based on Make-To-Stock (MTS), Pack-To-Order (PTO) and Grind-
To-Order (GTO) strategies. A Discrete-Event Simulation (DES)
model of SSCM is constructed using Arena software to implement
the three-target scenarios. We conclude with the simulation results
that (GTO) is the optimal supply chain strategy that demonstrates the
best economic, ecological and social performance in the cement
industry.
Abstract: This paper presents an investigation into the design of a flight control system, using a robust sliding mode control structure, designed using the exact feedback linearization procedure of the dynamic of a small-size autonomous helicopter in hover. The robustness of the controller in the context of stabilization and trajectory tracking with respect to small body forces and air resistance on the main and tail rotor, is analytically proved using Lyapunov approach. Some simulation results are presented to illustrate the performance and robustness of such controller in the presence of small body forces and air resistance.
Abstract: High Voltage (HV) transmission lines are widely
spread around residential places. They take all forms of shapes:
concrete, steel, and timber poles. Earth grid always form part of the
HV transmission structure, whereat soil resistivity value is one of the
main inputs when it comes to determining the earth grid
requirements. In this paper, the soil structure and its implication on
the electrode resistance of HV transmission poles will be explored. In
Addition, this paper will present simulation for various soil structures
using IEEE and Australian standards to verify the computation with
CDEGS software. Furthermore, the split factor behavior under
different soil resistivity structure will be presented using CDEGS
simulations.
Abstract: The Artificial immune systems algorithms are Meta
heuristic optimization method, which are used for clustering and
pattern recognition applications are abundantly. These algorithms in
multimodal optimization problems are more efficient than genetic
algorithms. A major drawback in these algorithms is their slow
convergence to global optimum and their weak stability can be
considered in various running of these algorithms. In this paper,
improved Artificial Immune System Algorithm is introduced for the
first time to overcome its problems of artificial immune system. That
use of the small size of a local search around the memory antibodies
is used for improving the algorithm efficiently. The credibility of the
proposed approach is evaluated by simulations, and it is shown that
the proposed approach achieves better results can be achieved
compared to the standard artificial immune system algorithms
Abstract: A generalized method for small-signal simulation of
avalanche noise in Mixed Tunneling Avalanche Transit Time
(MITATT) device is presented in this paper where the effect of series
resistance is taken into account. The method is applied to a
millimeter-wave Double Drift Region (DDR) MITATT device based
on Silicon to obtain noise spectral density and noise measure as a
function of frequency for different values of series resistance. It is
found that noise measure of the device at the operating frequency
(122 GHz) with input power density of 1010 Watt/m2 is about 35 dB
for hypothetical parasitic series resistance of zero ohm (estimated
junction temperature = 500 K). Results show that the noise measure
increases as the value of parasitic resistance increases.