Abstract: This paper presents the experimental results of
discharge current phenomena on various humidity, temperature,
pressure and pollutant conditions of epoxy resin specimen. The
leakage distance of specimen was 3 cm, that it was supplied by high
voltage. The polluted condition was given with NaCl artificial
pollutant. The conducted measurements were discharge current and
applied voltage. The specimen was put in a hermetically sealed
chamber, and the current waveforms were analyzed with FFT.
The result indicated that on discharge condition, the fifth
harmonics still had dominant, rather than third one. The third
harmonics tent to be appeared on low pressure heavily polluted
condition, and followed by high humidity heavily polluted condition.
On the heavily polluted specimen, the peaks discharge current points
would be high and more frequent. Nevertheless, the specimen still
had capacitive property. Besides that, usually discharge current
points were more frequent. The influence of low pressure was still
dominant to be easier to discharge. The non-linear property would be
appear explicitly on low pressure and heavily polluted condition.
Abstract: A way of generating millimeter wave I/Q signal using inductive resonator matched poly-phase filter is suggested. Normally the poly-phase filter generates quite accurate I/Q phase and magnitude but the loss of the filter is considerable due to series connection of passive RC components. This loss term directly increases system noise figure when the poly-phase filter is used in RF Front-end. The proposed matching method eliminates above mentioned loss and in addition provides gain on the passive filter. The working algorithm is illustrated by mathematical analysis. The generated I/Q signal is used in implementing millimeter wave phase shifter for the 60 GHz communication system to verify its effectiveness. The circuit is fabricated in 90 nm TSMC RF CMOS process under 1.2 V supply voltage. The measurement results showed that the suggested method improved gain by 6.5 dB and noise by 2.3 dB. The summary of the proposed I/Q generation is compared with previous works.
Abstract: Sputter deposition processes, especially for sputtering
from metal targets, are well investigated. For practical reasons, i.e.
for industrial processes, energetic considerations for sputter
deposition are useful in order to optimize the sputtering process. In
particular, for substrates at floating conditions it is required to obtain
energetic conditions during film growth that enables sufficient dense
metal films of good quality. The influence of ion energies, energy
density and momentum transfer is thus examined both for sputtering
at the target as well as during film growth. Different regimes
dominated by ion energy, energy density and momentum transfer
were identified by using different plasma sources and by varying
power input, pressure and bias voltage.
Abstract: A basic conceptual study of TCSC device on Simulink is a teaching aid and helps in understanding the rudiments of the topic. This paper thus stems out from basics of TCSC device and analyzes the impedance characteristics and associated single & multi resonance conditions. The Impedance characteristics curve is drawn for different values of inductance in MATLAB using M-files. The study is also helpful in estimating the appropriate inductance and capacitance values which have influence on multi resonance point in TCSC device. The capacitor voltage, line current, thyristor current and capacitor current waveforms are discussed briefly as simulation results. Simulink model of TCSC device is given and corresponding waveforms are analyzed. The subsidiary topics e.g. power oscillation damping, SSR mitigation and transient stability is also brought out.
Abstract: In this work, the physical based device model of
AlGaN/GaN high electron mobility transistors (HEMTs) has been
established and the corresponding device operation behavior has
been investigated also by using Sentaurus TCAD from Synopsys.
Advanced AlGaN/GaN hetero-structures with GaN cap layer and AlN
spacer have been considered and the GaN cap layer and AlN spacer
are found taking important roles on the gate leakage blocking and
off-state breakdown voltage enhancement.
Abstract: In this paper the behavior of fixed series compensated
extra high voltage transmission lines during faults is simulated. Many
over-voltage protection schemes for series capacitors are limited in
terms of size and performance, and are easily affected by
environmental conditions. While the need for more compact and
environmentally robust equipment is required. use of series
capacitors for compensating part of the inductive reactance of long
transmission lines increases the power transmission capacity.
Emphasis is given on the impact of modern capacitor protection
techniques (MOV protection). The simulation study is performed
using MATLAB/SIMULINK®and results are given for a three phase
and a single phase to ground fault.
Abstract: This paper describes a low-voltage and low-power
channel selection analog front end with continuous-time low pass
filters and highly linear programmable gain amplifier (PGA). The
filters were realized as balanced Gm-C biquadratic filters to achieve a
low current consumption. High linearity and a constant wide
bandwidth are achieved by using a new transconductance (Gm) cell.
The PGA has a voltage gain varying from 0 to 65dB, while
maintaining a constant bandwidth. A filter tuning circuit that requires
an accurate time base but no external components is presented.
With a 1-Vrms differential input and output, the filter achieves
-85dB THD and a 78dB signal-to-noise ratio. Both the filter and PGA
were implemented in a 0.18um 1P6M n-well CMOS process. They
consume 3.2mW from a 1.8V power supply and occupy an area of
0.19mm2.
Abstract: This paper presents a method for the optimal
allocation of Distributed generation in distribution systems. In this
paper, our aim would be optimal distributed generation allocation for
voltage profile improvement and loss reduction in distribution
network. Genetic Algorithm (GA) was used as the solving tool,
which referring two determined aim; the problem is defined and
objective function is introduced. Considering to fitness values
sensitivity in genetic algorithm process, there is needed to apply load
flow for decision-making. Load flow algorithm is combined
appropriately with GA, till access to acceptable results of this
operation. We used MATPOWER package for load flow algorithm
and composed it with our Genetic Algorithm. The suggested method
is programmed under MATLAB software and applied ETAP
software for evaluating of results correctness. It was implemented on
part of Tehran electricity distributing grid. The resulting operation of
this method on some testing system is illuminated improvement of
voltage profile and loss reduction indexes.
Abstract: In the past many uneconomic solutions for limitation
and interruption of short-circuit currents in low power applications
have been introduced, especially polymer switch based on the
positive temperature coefficient of resistance (PCTR) concept.
However there are many limitations in the active material, which
consists of conductive fillers. This paper presents a significantly
improved and simplified approach that replaces the existing current
limiters with faster switching elements. Its elegance lies in the
remarkable simplicity and low-cost processes of producing the device
using polyaniline (PANI) doped with methane-sulfonic acid (MSA).
Samples characterized as lying in the metallic and critical regimes of
metal insulator transition have been studied by means of electrical
performance in the voltage range from 1V to 5 V under different
environmental conditions. Moisture presence is shown to increase the
resistivity and also improved its current limiting performance.
Additionally, the device has also been studied for electrical resistivity
in the temperature range 77 K-300 K. The temperature dependence of
the electrical conductivity gives evidence for a transport mechanism
based on variable range hopping in three dimensions.
Abstract: Series compensators have been used for many years,
to increase the stability and load ability of transmission line. They
compensate retarded or advanced volt drop of transmission lines
by placing advanced or retarded voltage in series with them to
compensate the effective reactance, which cause to increase load
ability of transmission lines. In this paper, two method of fuzzy
controller, based on power reference tracking and impedance
reference tracking have been developed on TCSC controller in
order to increase load ability and improving power oscillation
damping of system. In these methods, fire angle of thyristors are
determined directly through the special Rule-bases with the error
and change of error as the inputs. The simulation results of two
area four- machines power system show the good performance of
power oscillation damping in system. Comparison of this method
with classical PI controller shows the increasing speed of system
response in power oscillation damping.
Abstract: Herein, the organic semiconductor methyl orange
(MO), is investigated for the first time for its electronic applications.
For this purpose, Al/MO/n-Si heterojunction is fabricated through
economical cheap and simple “drop casting” technique. The currentvoltage
(I-V) measurements of the device are made at room
temperature under dark conditions. The I-V characteristics of
Al/MO/n-Si junction exhibits asymmetrical and rectifying behavior
that confirms the formation of diode. The diode parameters such as
rectification ratio (RR), turn on voltage (Vturn on), reverse saturation
current (I0), ideality factor (n), barrier height ( b
f ), series resistance
(Rs) and shunt resistance (Rsh) are determined from I-V curves using
Schottky equations. These values of these parameters are also
extracted and verified by applying Cheung’s functions. The
conduction mechanisms are explained from the forward bias I-V
characteristics using the power law.
Abstract: The designing of charge pump with high gain Op-
Amp is a challenging task for getting faithful response .Design of
high performance phase locked loop require ,a design of high
performance charge pump .We have designed a operational amplifier
for reducing the error caused by high speed glitch in a transistor and
mismatch currents . A separate Op-Amp has designed in 180 nm
CMOS technology by CADENCE VIRTUOSO tool. This paper
describes the design of high performance charge pump for GHz
CMOS PLL targeting orthogonal frequency division multiplexing
(OFDM) application. A high speed low power consumption Op-Amp
with more than 500 MHz bandwidth has designed for increasing the
speed of charge pump in Phase locked loop.
Abstract: Selective harmonic elimination-pulse width modulation techniques offer a tight control of the harmonic spectrum of a given voltage waveform generated by a power electronic converter along with a low number of switching transitions. Traditional optimization methods suffer from various drawbacks, such as prolonged and tedious computational steps and convergence to local optima; thus, the more the number of harmonics to be eliminated, the larger the computational complexity and time. This paper presents a novel method for output voltage harmonic elimination and voltage control of PWM AC/AC voltage converters using the principle of hybrid Real-Coded Genetic Algorithm-Pattern Search (RGA-PS) method. RGA is the primary optimizer exploiting its global search capabilities, PS is then employed to fine tune the best solution provided by RGA in each evolution. The proposed method enables linear control of the fundamental component of the output voltage and complete elimination of its harmonic contents up to a specified order. Theoretical studies have been carried out to show the effectiveness and robustness of the proposed method of selective harmonic elimination. Theoretical results are validated through simulation studies using PSIM software package.
Abstract: This paper studies dynamic stability of homogeneous
beams with piezoelectric layers subjected to periodic axial
compressive load that is simply supported at both ends lies on a
continuous elastic foundation. The displacement field of beam is
assumed based on Bernoulli-Euler beam theory. Applying the
Hamilton's principle, the governing dynamic equation is established.
The influences of applied voltage, foundation coefficient and
piezoelectric thickness on the unstable regions are presented. To
investigate the accuracy of the present analysis, a compression study
is carried out with a known data.
Abstract: In this paper a new approach for transmission pricing
is presented. The main idea is voltage angle allocation, i.e.
determining the contribution of each contract on the voltage angle of
each bus. DC power flow is used to compute a primary solution for
angle decomposition. To consider the impacts of system non-linearity
on angle decomposition, the primary solution is corrected in different
iterations of decoupled Newton-Raphson power flow. Then, the
contribution of each contract on power flow of each transmission line
is computed based on angle decomposition. Contract-related flows
are used as a measure for “extent of use" of transmission network
capacity and consequently transmission pricing. The presented
approach is applied to a 4-bus test system and IEEE 30-bus test
system.
Abstract: This paper focuses on PSS/E modeling of wind farms
of Doubly-fed Induction Generator (DFIG) type and their impact on
issues of power system operation. Since Wind Turbine Generators
(WTG) don-t have the same characteristics as synchronous
generators, the appropriate modeling of wind farms is essential for
transmission system operators to analyze the best options of
transmission grid reinforcements as well as to evaluate the wind
power impact on reliability and security of supply. With the high
excepted penetration of wind power into the power system a
simultaneous loss of Wind Farm generation will put at risk power
system security and reliability. Therefore, the main wind grid code
requirements concern the fault ride through capability and frequency
operation range of wind turbines. In case of grid faults wind turbines
have to supply a definite reactive power depending on the
instantaneous voltage and to return quickly to normal operation.
Abstract: In this paper, we have developed an explicit analytical
drain current model comprising surface channel potential and
threshold voltage in order to explain the advantages of the proposed
Gate Stack Double Diffusion (GSDD) MOSFET design over the
conventional MOSFET with the same geometric specifications that
allow us to use the benefits of the incorporation of the high-k layer
between the oxide layer and gate metal aspect on the immunity of the
proposed design against the self-heating effects. In order to show the
efficiency of our proposed structure, we propose the simulation of the
power chopper circuit. The use of the proposed structure to design a
power chopper circuit has showed that the (GSDD) MOSFET can
improve the working of the circuit in terms of power dissipation and
self-heating effect immunity. The results so obtained are in close
proximity with the 2D simulated results thus confirming the validity
of the proposed model.
Abstract: This paper presents an application of particle swarm
optimization (PSO) to the grounding grid planning which compares to
the application of genetic algorithm (GA). Firstly, based on IEEE
Std.80, the cost function of the grounding grid and the constraints of
ground potential rise, step voltage and touch voltage are constructed
for formulating the optimization problem of grounding grid planning.
Secondly, GA and PSO algorithms for obtaining optimal solution of
grounding grid are developed. Finally, a case of grounding grid
planning is shown the superiority and availability of the PSO
algorithm and proposal planning results of grounding grid in cost and
computational time.
Abstract: An organic bulk heterojunction (BHJ) was fabricated using a blended film containing Copper (II) tetrakis(4-acumylphenoxy) phthalocyanine (Tc-CuPc) along with [6,6]-Phenyl C61 butyric acid methyl ester (PCBM). Weight ratio between Tc-CuPc and PCBM was 1:1. The electrical properties of Tc-CuPc: PCBM BHJ were examined. Rectifying nature of the BHJ was displayed by current-voltage (I-V) curves, recorded in dark and at various temperatures. At low voltages, conduction was ohmic succeeded by space-charge limiting current (SCLC) conduction at higher voltages in which exponential trap distribution was dominant. Series resistance, shunt resistance, ideality factor, effective barrier height and mobility at room temperature were found to be 526 4, 482 k4, 3.7, 0.17 eV and 2×10-7 cm2V-1s-1 respectively. Temperature effect towards different BHJ parameters was observed under dark condition.
Abstract: Air bubbles have been detected in human circulation
of end-stage renal disease patients who are treated by hemodialysis.
The consequence of air embolism, air bubbles, is under recognized
and usually overlooked in daily practice. This paper shows results of
a capacitor based detection method that capable of detecting the
presence of air bubbles in the blood stream in different frequencies.
The method is based on a parallel plates capacitor made of platinum
with an area of 1.5 cm2 and a distance between the two plates is 1cm.
The dielectric material used in this capacitor is Dextran70 solution
which mimics blood rheology. Simulations were carried out using
RC circuit at two frequencies 30Hz and 3 kHz and results compared
with experiments and theory. It is observed that by injecting air
bubbles of different diameters into the device, there were significant
changes in the capacitance of the capacitor. Furthermore, it is
observed that the output voltage from the circuit increased with
increasing air bubble diameter. These results demonstrate the
feasibility of this approach in improving air bubble detection in
Hemodialysis.