Abstract: A wireless sensor network with a large number of tiny sensor nodes can be used as an effective tool for gathering data in various situations. One of the major issues in wireless sensor networks is developing an energy-efficient routing protocol which has a significant impact on the overall lifetime of the sensor network. In this paper, we propose a novel hierarchical with static clustering routing protocol called Energy-Efficient Protocol with Static Clustering (EEPSC). EEPSC, partitions the network into static clusters, eliminates the overhead of dynamic clustering and utilizes temporary-cluster-heads to distribute the energy load among high-power sensor nodes; thus extends network lifetime. We have conducted simulation-based evaluations to compare the performance of EEPSC against Low-Energy Adaptive Clustering Hierarchy (LEACH). Our experiment results show that EEPSC outperforms LEACH in terms of network lifetime and power consumption minimization.
Abstract: Wind turbines with double output induction
generators can operate at variable speed permitting conversion
efficiency maximization over a wide range of wind velocities. This
paper presents the performance analysis of a wind driven double
output induction generator (DOIG) operating at varying shafts speed.
A periodic transient state analysis of DOIG equipped with two
converters is carried out using a hybrid induction machine model.
This paper simulates the harmonic content of waveforms in various
points of drive at different speeds, based on the hybrid model
(dqabc). Then the sinusoidal and trapezoidal pulse-width–modulation
control techniques are used in order to improve the power factor of
the machine and to weaken the injected low order harmonics to the
supply. Based on the frequency spectrum, total harmonics distortion,
distortion factor and power factor. Finally advantages of sinusoidal
and trapezoidal pulse width modulation techniques are compared.
Abstract: Whereas in the third generation nuclear reactors,
dimensions of core and also the kind of coolant and enrichment
percent of fuel have significantly changed than the second
generation, therefore in this article the aim is based on a
comparative investigation between two same power reactors of
second and third generations, that the neutronic parameters of both
reactors such as: K∞, Keff and its details and thermal hydraulic
parameters such as: power density, specific power, volumetric heat
rate, released power per fuel volume unit, volume and mass of clad
and fuel (consisting fissile and fertile fuels), be calculated and
compared together. By this comparing the efficiency and
modification of third generation nuclear reactors than second
generation which have same power can be distinguished.
In order to calculate the cited parameters, some information
such as: core dimensions, the pitch of lattice, the fuel matter, the
percent of enrichment and the kind of coolant are used. For
calculating the neutronic parameters, a neutronic program entitled:
SIXFAC and also related formulas have been used. Meantime for
calculating the thermal hydraulic and other parameters, analytical
method and related formulas have been applied.
Abstract: Most electrical distribution systems are incurring large
losses as the loads are wide spread, inadequate reactive power
compensation facilities and their improper control. A typical static
VAR compensator consists of capacitor bank in binary sequential
steps operated in conjunction with a thyristor controlled reactor of the
smallest step size. This SVC facilitates stepless control of reactive
power closely matching with load requirements so as to maintain
power factor nearer to unity. This type of SVC-s requiring a
appropriately controlled TCR. This paper deals with an air cored
reactor suitable for distribution transformer of 3phase, 50Hz, Dy11,
11KV/433V, 125 KVA capacity. Air cored reactors are designed,
built, tested and operated in conjunction with capacitor bank in five
binary sequential steps. It is established how the delta connected TCR
minimizes the harmonic components and the operating range for
various electrical quantities as a function of firing angle is
investigated. In particular firing angle v/s line & phase currents, D.C.
components, THD-s, active and reactive powers, odd and even triplen
harmonics, dominant characteristic harmonics are all investigated and
range of firing angle is fixed for satisfactory operation. The harmonic
spectra for phase and line quantities at specified firing angles are
given. In case the TCR is operated within the bound specified in this
paper established through simulation studies are yielding the best
possible operating condition particularly free from all dominant
harmonics.
Abstract: As global industry developed rapidly, the energy
demand also rises simultaneously. In the production process, there’s a
lot of energy consumed in the process. Formally, the energy used in
generating the heat in the production process. In the total energy
consumption, 40% of the heat was used in process heat, mechanical
work, chemical energy and electricity. The remaining 50% were
released into the environment. It will cause energy waste and
environment pollution. There are many ways for recovering the waste
heat in factory. Organic Rankine Cycle (ORC) system can produce
electricity and reduce energy costs by recovering the waste of low
temperature heat in the factory. In addition, ORC is the technology
with the highest power generating efficiency in low-temperature heat
recycling. However, most of factories executives are still hesitated
because of the high implementation cost of the ORC system, even a lot
of heat are wasted. Therefore, this study constructs a nonlinear
mathematical model of waste heat recovery equipment configuration
to maximize profits. A particle swarm optimization algorithm is
developed to generate the optimal facility installation plan for the ORC
system.
Abstract: In this work, we analyze the deformation of surface
waves in shallow flows conditions, propagating in a channel of
slowly varying cross-section. Based on a singular perturbation
technique, the main purpose is to predict the motion of waves by
using a dimensionless formulation of the governing equations,
considering that the longitudinal variation of the transversal section
obey a power-law distribution. We show that the spatial distribution
of the waves in the varying cross-section is a function of a kinematic
parameter,κ , and two geometrical parameters εh
and w ε . The above
spatial behavior of the surface elevation is modeled by an ordinary
differential equation. The use of single formulas to model the varying
cross sections or transitions considered in this work can be a useful
approximation to natural or artificial geometrical configurations.
Abstract: Multi-site damage (MSD) has been a challenge to
aircraft, civil and power plant structures. In real life components are subjected to cracking at many vulnerable locations such as the bolt
holes. However, we do not consider for the presence of multiple cracks. Unlike components with a single crack, these components are
difficult to predict. When two cracks approach one another, their
stress fields influence each other and produce enhancing or shielding effect depending on the position of the cracks. In the present study,
numerical studies on fracture analysis have been conducted by using
the developed code based on the modified virtual crack closure integral (MVCCI) technique and finite element analysis (FEA) software ABAQUS for computing SIF of plates with multiple cracks.
Various parametric studies have been carried out and the results have
been compared with literature where ever available and also with the solution, obtained by using ABAQUS. By conducting extensive
numerical studies expressions for SIF have been obtained for collinear cracks and non-aligned cracks.
Abstract: A glider is in essence an unpowered vehicle and in this project we designed and built an oceanic glider, designed to operate underwater. This Glider was designed to collect ocean data such as temperature, pressure and (in future measures physical dimensions of the operating environment) and output this data to an external source. Development of the Oceanic Glider required research into various actuation systems that control buoyancy, pitch and yaw and the dynamics of these systems. It also involved the design and manufacture of the Glider and the design and implementation of a controller that enabled the Glider to navigate and move in an appropriate manner.
Abstract: In a wireless communication system, a
predistorter(PD) is often employed to alleviate nonlinear distortions
due to operating a power amplifier near saturation, thereby improving
the system performance and reducing the interference to adjacent
channels. This paper presents a new adaptive polynomial digital
predistorter(DPD). The proposed DPD uses Coordinate Rotation
Digital Computing(CORDIC) processors and PD process by pipelined
architecture. It is simpler and faster than conventional adaptive
polynomial DPD. The performance of the proposed DPD is proved by
MATLAB simulation.
Abstract: Bangladesh is a developing country with large
population. Demand of electrical energy is increasing day by day
because of increasing population and industrialization. But due to
limited resources, people here are suffering from power crisis
problem which is considered as a major obstacle to the economic
development. In most of the cases, it is extremely difficult to extend
high tension transmission lines to some of the places that are
separated from the mainland. Renewable energy is considered to be
the right choice for providing clean energy to these remote
settlements. This paper proposes a cost effective design of off-grid
wind-diesel hybrid power system using combined heat and power
(CHP) technology in a grid isolated island, Sandwip, Bangladesh.
Design and simulation of the wind-diesel hybrid power system is
performed considering different factors for the island Sandwip.
Detailed economic analysis and comparison with solar PV system
clearly reveals that wind-diesel hybrid power system can be a cost
effective solution for the isolated island like Sandwip.
Abstract: In this paper, a new technique of signal detection has been proposed for detecting the orthogonal frequency-division multiplexing (OFDM) signal in the presence of nonlinear distortion.There are several advantages of OFDM communications system.However, one of the existing problems is remain considered as the nonlinear distortion generated by high-power-amplifier at the transmitter end due to the large dynamic range of an OFDM signal. The proposed method is the maximum likelihood detection with the symbol estimation. When the training data are available, the neural network has been used to learn the characteristic of received signal and to estimate the new positions of the transmitted symbol which are provided to the maximum likelihood detector. Resulting in the system performance, the nonlinear distortions of a traveling wave tube amplifier with OFDM signal are considered in this paper.Simulation results of the bit-error-rate performance are obtained with 16-QAM OFDM systems.
Abstract: The objective of this study is to propose an observer design for nonlinear systems by using an augmented linear system derived by application of a formal linearization method. A given nonlinear differential equation is linearized by the formal linearization method which is based on Taylor expansion considering up to the higher order terms, and a measurement equation is transformed into an augmented linear one. To this augmented dimensional linear system, a linear estimation theory is applied and a nonlinear observer is derived. As an application of this method, an estimation problem of transient state of electric power systems is studied, and its numerical experiments indicate that this observer design shows remarkable performances for nonlinear systems.
Abstract: This article presents a current-mode quadrature
oscillator using differential different current conveyor (DDCC) and
voltage differencing transconductance amplifier (VDTA) as active
elements. The proposed circuit is realized fro m a non-inverting
lossless integrator and an inverting second order low-pass filter. The
oscillation condition and oscillation frequency can be
electronically/orthogonally controlled via input bias currents. The
circuit description is very simple, consisting of merely 1 DDCC, 1
VDTA, 1 grounded resistor and 3 grounded capacitors. Using only
grounded elements, the proposed circuit is then suitable for IC
architecture. The proposed oscillator has high output impedance
which is easy to cascade or dive the external load without the buffer
devices. The PSPICE simulation results are depicted, and the given
results agree well with the theoretical anticipation. The power
consumption is approximately 1.76mW at ±1.25V supply voltages.
Abstract: This paper presents a numerical analysis of the
performance of a five-bladed Darrieus vertical-axis water turbine,
based on the NACA 0025 blade profile, for both bare and shrouded
configurations. A complete campaign of 2-D simulations, performed
for several values of tip speed ratio and based on RANS unsteady
calculations, has been performed to obtain the rotor torque and power
curves. Also the effect of a NACA-shaped central hydrofoil has been
investigated, with the aim of evaluating the impact of a solid
blockage on the performance of the shrouded rotor configuration.
The beneficial effect of the shroud on rotor overall performances
has clearly been evidenced, while the adoption of the central
hydrofoil has proved to be detrimental, being the resulting flow slow
down (due to the presence of the obstacle) much higher with respect
to the flow acceleration (due to the solid blockage effect).
Abstract: The study in this paper underlines the importance of
correct joint selection of the spreading codes for uplink of multicarrier
code division multiple access (MC-CDMA) at the transmitter
side and detector at the receiver side in the presence of nonlinear
distortion due to high power amplifier (HPA). The bit error rate
(BER) of system for different spreading sequences (Walsh code, Gold
code, orthogonal Gold code, Golay code and Zadoff-Chu code) and
different kinds of receivers (minimum mean-square error receiver
(MMSE-MUD) and microstatistic multi-user receiver (MSF-MUD))
is compared by means of simulations for MC-CDMA transmission
system. Finally, the results of analysis will show, that the application
of MSF-MUD in combination with Golay codes can outperform
significantly the other tested spreading codes and receivers for all
mostly used models of HPA.
Abstract: This article presents the simulation, parameterization and optimization of an electromagnet with the C–shaped configuration, intended for the study of magnetic properties of materials. The electromagnet studied consists of a C-shaped yoke, which provides self–shielding for minimizing losses of magnetic flux density, two poles of high magnetic permeability and power coils wound on the poles. The main physical variable studied was the static magnetic flux density in a column within the gap between the poles, with 4cm2 of square cross section and a length of 5cm, seeking a suitable set of parameters that allow us to achieve a uniform magnetic flux density of 1x104 Gaussor values above this in the column, when the system operates at room temperature and with a current consumption not exceeding 5A. By means of a magnetostatic analysis by the finite element method, the magnetic flux density and the distribution of the magnetic field lines were visualized and quantified. From the results obtained by simulating an initial configuration of electromagnet, a structural optimization of the geometry of the adjustable caps for the ends of the poles was performed. The magnetic permeability effect of the soft magnetic materials used in the poles system, such as low– carbon steel (0.08% C), Permalloy (45% Ni, 54.7% Fe) and Mumetal (21.2% Fe, 78.5% Ni), was also evaluated. The intensity and uniformity of the magnetic field in the gap showed a high dependence with the factors described above. The magnetic field achieved in the column was uniform and its magnitude ranged between 1.5x104 Gauss and 1.9x104 Gauss according to the material of the pole used, with the possibility of increasing the magnetic field by choosing a suitable geometry of the cap, introducing a cooling system for the coils and adjusting the spacing between the poles. This makes the device a versatile and scalable tool to generate the magnetic field necessary to perform magnetic characterization of materials by techniques such as vibrating sample magnetometry (VSM), Hall-effect, Kerr-effect magnetometry, among others. Additionally, a CAD design of the modules of the electromagnet is presented in order to facilitate the construction and scaling of the physical device.
Abstract: Computerized alarm systems have been applied
increasingly to nuclear power plants. For existing plants, an add-on
computer alarm system is often installed to the control rooms. Alarm
avalanches during the plant transients are major problems with the
alarm systems in nuclear power plants. Computerized alarm systems
can process alarms to reduce the number of alarms during the plant
transients. This paper describes various alarm processing methods, an
alarm cause tracking function, and various alarm presentation schemes
to show alarm information to the operators effectively which are
considered during the development of several computerized alarm
systems for Korean nuclear power plants and are found to be helpful to
the operators.
Abstract: This paper present a MATLAB-SIMULINK model of a single phase 2.5 KVA, 240V RMS controlled PV VSI (Photovoltaic Voltage Source Inverter) inverter using IGBTs (Insulated Gate Bipolar Transistor). The behavior of output voltage, output current, and the total harmonic distortion (THD), with the variation in input dc blocking capacitor (Cdc), for linear and non-linear load has been analyzed. The values of Cdc as suggested by the other authors in their papers are not clearly defined and it poses difficulty in selecting the proper value. As the dc power stored in Cdc, (generally placed parallel with battery) is used as input to the VSI inverter. The simulation results shows the variation in the output voltage and current with different values of Cdc for linear and non-linear load connected at the output side of PV VSI inverter and suggest the selection of suitable value of Cdc.
Abstract: A model of vortex wake is suggested to determine the
induced power during animal hovering flight. The wake is modeled
by a series of equi-spaced rigid rectangular vortex plates, positioned
horizontally and moving vertically downwards with identical speeds;
each plate is generated during powering of the functionally wing
stroke. The vortex representation of the wake considered in the
current theory allows a considerable loss of momentum to occur. The
current approach accords well with the nature of the wingbeat since it
considers the unsteadiness in the wake as an important fluid
dynamical characteristic. Induced power in hovering is calculated as
the aerodynamic power required to generate the vortex wake system.
Specific mean induced power to mean wing tip velocity ratio is
determined by solely the normal spacing parameter (f) for a given
wing stroke amplitude. The current theory gives much higher specific
induced power estimate than anticipated by classical methods.
Abstract: Since injection engines have a considerable portion, in
consumption of energy and environmental pollution, using an
alternative source of energy with lower pollutant effects in this
regard is necessary.
Biodiesel fuel is a suitable alternative for gasoline in diesel
engines.
In this research the property of biodiesel, the function and the
pollution effects of diesel engine, when using 100% biodiesel, using
100% gasoline and mixing ratio of both fuels for comparing them,
have been investigated.
The researches have shown, using biodiesel fuel in prevalent
diesel engine, will reduce the pollutants such as Co, half burned
carbohydrate and suspended particles and a little increase in
oxidation will achieve while power consumption, particularly fuel
and thermal efficiency of diesel fuel has the same.