Abstract: This paper proposes a zero-voltage transition (ZVT) PWM synchronous buck converter, which is designed to operate at low output voltage and high efficiency typically required for portable systems. To make the DC-DC converter efficient at lower voltage, synchronous converter is an obvious choice because of lower conduction loss in the diode. The high-side MOSFET is dominated by the switching losses and it is eliminated by the soft switching technique. Additionally, the resonant auxiliary circuit designed is also devoid of the switching losses. The suggested procedure ensures an efficient converter. Theoretical analysis, computer simulation, and experimental results are presented to explain the proposed schemes.
Abstract: This paper presents a practical scheme that can be used for allocating the transmission loss to generators and loads. In this scheme first the share of a generator or load on the current through a branch is determined using Z-bus modified matrix. Then the current components are decomposed and the branch loss allocation is obtained. A motivation of proposed scheme is to improve the results of Z-bus method and to reach more fair allocation. The proposed scheme has been implemented and tested on several networks. To achieve practical and applicable results, the proposed scheme is simulated and compared on the transmission network (400kv) of Khorasan region in Iran and the 14-bus standard IEEE network. The results show that the proposed scheme is comprehensive and fair to allocating the energy losses of a power market to its participants.
Abstract: This paper presents the development and application of an adaptive neuro fuzzy inference system (ANFIS) based intelligent hybrid neuro fuzzy controller for automatic generation control (AGC) of two-area interconnected thermal power system with reheat non linearity. The dynamic response of the system has been studied for 1% step load perturbation in area-1. The performance of the proposed neuro fuzzy controller is compared against conventional proportional-integral (PI) controller, state feedback linear quadratic regulator (LQR) controller and fuzzy gain scheduled proportionalintegral (FGSPI) controller. Comparative analysis demonstrates that the proposed intelligent neuro fuzzy controller is the most effective of all in improving the transients of frequency and tie-line power deviations against small step load disturbances. Simulations have been performed using Matlab®.
Abstract: Dynamic of phytoplankton blooms in the Baltic Sea
has been analyzed applying the numerical ecosystem model 3D
CEMBS. The model consists of the hydrodynamic model (POP,
version 2.1) and the ice model (CICE, version 4.0), which are
imposed by the atmospheric data model (DATM7). The 3D
model has an ecosystem module, activated in 2012 in the operational
mode. The ecosystem model consists of 11 main variables: biomass
of small-size phytoplankton and large-size phytoplankton
and cyanobacteria, zooplankton biomass, dissolved and molecular
detritus, dissolved oxygen concentration, as well as concentrations of
nutrients, including: nitrates, ammonia, phosphates and silicates. The
3D-CEMBS model is an effective tool for solving problems related to
phytoplankton blooms dynamic in the Baltic Sea
Abstract: The kinematics of manipulators is a central problem in the automatic control of robot manipulators. Theoretical background for the analysis of the 5 Dof Lynx-6 educational Robot Arm kinematics is presented in this paper. The kinematics problem is defined as the transformation from the Cartesian space to the joint space and vice versa. The Denavit-Harbenterg (D-H) model of representation is used to model robot links and joints in this study. Both forward and inverse kinematics solutions for this educational manipulator are presented, An effective method is suggested to decrease multiple solutions in inverse kinematics. A visual software package, named MSG, is also developed for testing Motional Characteristics of the Lynx-6 Robot arm. The kinematics solutions of the software package were found to be identical with the robot arm-s physical motional behaviors.
Abstract: The simulation of external aerodynamics is one of the most challenging and important automotive CFD applications. With the rapid developments of digital computers, CFD is used as a practical tool in modern fluid dynamics research. It integrates fluid mechanics disciplines, mathematics and computer science. In this study, two different types of simulations were made, one for the flow around a simplified high speed passenger car with a rear-spoiler and the other for the flow without a rear-spoiler. The standard k-ε model is selected to numerically simulate the external flow field of the simplified Camry model with or without a rear-spoiler. Through an analysis of the simulation results, a new rear spoiler is designed and it shows a mild reduction of the vehicle aerodynamics drag. This leads to less vehicle fuel consumption on the road.
Abstract: The process of wafer fabrication is arguably the most
technologically complex and capital intensive stage in semiconductor
manufacturing. This large-scale discrete-event process is highly reentrant,
and involves hundreds of machines, restrictions, and
processing steps. Therefore, production control of wafer fabrication
facilities (fab), specifically scheduling, is one of the most challenging
problems that this industry faces. Dispatching rules have been
extensively applied to the scheduling problems in semiconductor
manufacturing. Moreover, lot release policies are commonly used in
this manufacturing setting to further improve the performance of such
systems and reduce its inherent variability. In this work, simulation is
used in the scheduling of re-entrant flow shop manufacturing systems
with an application in semiconductor wafer fabrication; where, a
simulation model has been developed for the Intel Five-Machine Six
Step Mini-Fab using the ExtendTM simulation environment. The
Mini-Fab has been selected as it captures the challenges involved in
scheduling the highly re-entrant semiconductor manufacturing lines.
A number of scenarios have been developed and have been used to
evaluate the effect of different dispatching rules and lot release
policies on the selected performance measures. Results of simulation
showed that the performance of the Mini-Fab can be drastically
improved using a combination of dispatching rules and lot release
policy.
Abstract: There are reports of gas and oil wells fire due to different accidents. Many different methods are used for fire fighting in gas and oil industry. Traditional fire extinguishing techniques are mostly faced with many problems and are usually time consuming and needs lots of equipments. Besides, they cause damages to facilities, and create health and environmental problems. This article proposes innovative approach in fire extinguishing techniques in oil and gas industry, especially applicable for burning oil wells located offshore. Fire extinguishment employing a turbojet is a novel approach which can help to extinguishment the fire in short period of time. Divergent and convergent turbojets modeled in laboratory scale along with a high pressure flame were used. Different experiments were conducted to determine the relationship between output discharges of trumpet and oil wells. The results were corrected and the relationship between dimensionless parameters of flame and fire extinguishment distances and also the output discharge of turbojet and oil wells in specified distances are demonstrated by specific curves.
Abstract: The problem of controlling a two link robotic manipulator, consisting of a rotating and a prismatic links, is addressed. The actuations of both links are assumed to have unknown dead zone nonlinearities and friction torques modeled by LuGre friction model. Because of the existence of the unknown dead zone and friction torque at the actuations, unknown parameters and unmeasured states would appear to be part of the overall system dynamics that need for estimation. Unmeasured states observer, unknown parameters estimators, and robust adaptive control laws have been derived such that closed loop global stability is achieved. Simulation results have been performed to show the efficacy of the suggested approach.
Abstract: This paper presents an intelligent speed control
system based on fuzzy logic for a voltage source PWM inverter-fed
indirect vector controlled induction motor drive. Traditional indirect
vector control system of induction motor introduces conventional PI
regulator in outer speed loop; it is proved that the low precision of the
speed regulator debases the performance of the whole system. To
overcome this problem, replacement of PI controller by an intelligent
controller based on fuzzy set theory is proposed. The performance of
the intelligent controller has been investigated through digital
simulation using MATLAB-SIMULINK package for different
operating conditions such as sudden change in reference speed and
load torque. The simulation results demonstrate that the performance
of the proposed controller is better than that of the conventional PI
controller.
Abstract: In this article, using finite element analysis (FEA)
and an X-ray diffractometer (XRD), cold-sprayed titanium particles
on a steel substrate is investigated in term of cooling time and the
development of residual strains. Three cooling-down models of
sprayed particles after deposition stage are simulated and discussed:
the first model (m1) considers conduction effect to the substrate only,
the second model (m2) considers both conduction as well as
convection effect to the environment, and the third model (m3) which
is the same as the second model but with the substrate heated to a
near particle temperature before spraying. Thereafter, residual strains
developed in the third model is compared with the experimental
measurement of residual strains, which involved a Bruker D8
Advance Diffractometer using CuKa radiation (40kV, 40mA)
monochromatised with a graphite sample monochromator. For
deposition conditions of this study, a good correlation was found to
exist between the FEA results and XRD measurements of residual
strains.
Abstract: Since polymerase chain reaction (PCR) has been
invented, it has emerged as a powerful tool in genetic analysis. The
PCR products are closely linked with thermal cycles. Therefore, to
reduce the reaction time and make temperature distribution uniform in
the reaction chamber, a novel oscillatory thermal cycler is designed.
The sample is placed in a fixed chamber, and three constant isothermal
zones are established and lined in the system. The sample is oscillated
and contacted with three different isothermal zones to complete
thermal cycles. This study presents the design of the geometric
characteristics of the chamber. The commercial software
CFD-ACE+TM is utilized to investigate the influences of various
materials, heating times, chamber volumes, and moving speed of the
chamber on the temperature distributions inside the chamber. The
chamber moves at a specific velocity and the boundary conditions
with time variations are related to the moving speed. Whereas the
chamber moves, the boundary is specified at the conditions of the
convection or the uniform temperature. The user subroutines compiled
by the FORTRAN language are used to make the numerical results
realistically. Results show that the reaction chamber with a rectangular
prism is heated on six faces; the effects of various moving speeds of
the chamber on the temperature distributions are examined. Regarding
to the temperature profiles and the standard deviation of the
temperature at the Y-cut cross section, the non-uniform temperature
inside chamber is found as the moving speed is larger than 0.01 m/s.
By reducing the heating faces to four, the standard deviation of the
temperature of the reaction chamber is under 1.4×10-3K with the range
of velocities between 0.0001 m/s and 1 m/s. The nature convective
boundary conditions are set at all boundaries while the chamber moves
between two heaters, the effects of various moving velocities of the
chamber on the temperature distributions are negligible at the assigned
time duration.
Abstract: We address the problem of joint beamforming and multipath channel parameters estimation in Wideband Code Division Multiple Access (WCDMA) communication systems that employ Multiple-Access Interference (MAI) suppression techniques in the uplink (from mobile to base station). Most of the existing schemes rely on time multiplex a training sequence with the user data. In WCDMA, the channel parameters can also be estimated from a code multiplexed common pilot channel (CPICH) that could be corrupted by strong interference resulting in a bad estimate. In this paper, we present new methods to combine interference suppression together with channel estimation when using multiple receiving antennas by using adaptive signal processing techniques. Computer simulation is used to compare between the proposed methods and the existing conventional estimation techniques.
Abstract: This paper presents a solution for ceramic cutting tools availability in interrupted machining. Experiments were performed on a special fixture – the interrupted cut simulator. This fixture was constructed at our Department of Machining and Assembly within the scope of a project by the Czech Science Foundation. The goals of the tests were to contribute to the wider usage of these cutting materials in machining, especially in interrupted machining. Through the centuries, producers of ceramic cutting tools have taken big steps forward. Namely, increasing durability in maintaining high levels of strength and hardness lends an advantage. Some producers of these materials advise cutting inserts for interrupted machining at the present time [1, 2].
Abstract: A new interface circuit for capacitive sensor is
presented. This paper presents the design and simulation of soil
moisture capacitive sensor interface circuit based on phase
differential technique. The circuit has been designed and fabricated
using MIMOS- 0.35"m CMOS technology. Simulation and test
results show linear characteristic from 36 – 52 degree phase
difference, representing 0 – 100% in soil moisture level. Test result
shows the circuit has sensitivity of 0.79mV/0.10 phase difference,
translating into resolution of 10% soil moisture level.
Abstract: A topologically oriented neural network is very
efficient for real-time path planning for a mobile robot in changing
environments. When using a recurrent neural network for this
purpose and with the combination of the partial differential equation
of heat transfer and the distributed potential concept of the network,
the problem of obstacle avoidance of trajectory planning for a
moving robot can be efficiently solved. The related dimensional
network represents the state variables and the topology of the robot's
working space. In this paper two approaches to problem solution are
proposed. The first approach relies on the potential distribution of
attraction distributed around the moving target, acting as a unique
local extreme in the net, with the gradient of the state variables
directing the current flow toward the source of the potential heat. The
second approach considers two attractive and repulsive potential
sources to decrease the time of potential distribution. Computer
simulations have been carried out to interrogate the performance of
the proposed approaches.
Abstract: One of the major cause of eye strain and other
problems caused while watching television is the relative illumination between the screen and its surrounding. This can be
overcome by adjusting the brightness of the screen with respect to the surrounding light. A controller based on fuzzy logic is proposed
in this paper. The fuzzy controller takes in the intensity of light
surrounding the screen and the present brightness of the screen as input. The output of the fuzzy controller is the grid voltage corresponding to the required brightness. This voltage is given to CRT and brightness is controller dynamically. For the given test system data, different de-fuzzifier methods have been implemented and the results are compared. In order to validate the effectiveness of
the proposed approach, a fuzzy controller has been designed by obtaining a test data from a real time system. The simulations are
performed in MATLAB and are verified with standard system data. The proposed approach can be implemented for real time
applications.
Abstract: Electric vehicle (EV) is one of the effective solutions to
control emission of greenhouses gases in the world. It is of interest
for future transportation due to its sustainability and efficiency by
automotive manufacturers. Various electrical motors have been used
for propulsion system of electric vehicles in last decades. In this
paper brushed DC motor, Induction motor (IM), switched reluctance
motor (SRM) and brushless DC motor (BLDC) are simulated and
compared. BLDC motor is recommended for high performance
electric vehicles. PWM switching technique is implemented for speed
control of BLDC motor. Behavior of different modes of PWM speed
controller of BLDC motor are simulated in MATLAB/SIMULINK.
BLDC motor characteristics are compared and discussed for various
PWM switching modes under normal and inverter fault conditions.
Comparisons and discussions are verified through simulation results.
Abstract: In this paper present a sensorless maximum wind power extraction for variable speed constant frequency (VSCF) wind power generation systems with a doubly-fed induction generators (DFIG), to ensure stability and to impose the ideal feedback control solution despite of model uncertainties , using the principles of an active and reactive power controller (DPC) a robust sliding mode power control has been proposed to guarantees fast response times and precise control actions for control the active and reactive power independently. The simulation results in MATLAB/Simulink platform confirmed the good dynamic performance of power control approach for DFIGbased variable speed wind turbines.
Abstract: Nowadays, cardiac disease is one of the most common
cause of death. Each year almost one million of angioplasty interventions and stents implantations are made all over the world.
Unfortunately, in 20-30% of cases neointimal proliferations leads to
restenosis occurring within the following period of 3-6 months. Three major factors are believed to contribute mostly to the edge
restenosis: (a) mechanical damage of the artery-s wall caused by the
stent implantation, (b) interaction between the stent and the blood constituents and (c) endothelial growth stimulation by small (lower
that 1.5 Pa) and oscillating wall shear stress. Assuming that this last actor is particularly important, a numerical model of restenosis
basing on wall shear stress distribution in the stented artery was elaborated. A numerical simulations of the development of in-stent
restenosis have been performed and realistic geometric patterns of a
progressing lumen reduction have been obtained