Abstract: This paper addresses control of commutation of switched reluctance (SR) motor without the use of a physical position detector. Rotor position detection schemes for SR motor based on magnetisation characteristics of the motor use normal excitation or applied current /voltage pulses. The resulting schemes are referred to as passive or active methods respectively. The research effort is in realizing an economical sensorless SR rotor position detector that is accurate, reliable and robust to suit a particular application. An effective and reliable means of generating commutation signals of an SR motor based on inductance profile of its stator windings determined using active probing technique is presented. The scheme has been validated online using a 4-phase 8/6 SR motor and an 8-bit processor.
Abstract: In this paper, an approach for finding optimized
layouts for connecting PV units delivering maximum array output
power is suggested. The approach is based on considering the
different varying parameters of PV units that might be extracted from
a general two-diode model. These are mainly, solar irradiation,
reverse saturation currents, ideality factors, series and shunt
resistances in addition to operating temperature. The approach has
been tested on 19 possible 2×3 configurations and allowed to
determine the optimized configurations as well as examine the effects
of the different units- parameters on the maximum output power.
Thus, using this approach, standard arrays with n×m units can be
configured for maximum generated power and allows designing PV
based systems having reduced surfaces to fit specific required power,
as it is the case for solar cars and other mobile systems.
Abstract: The operating control parameters of injection
flushing type of electrical discharge machining process on stainless
steel 304 workpiece with copper tools are being optimized
according to its individual machining characteristic i.e. material
removal rate (MRR). Lower MRR during EDM machining process
may decrease its- machining productivity. Hence, the quality
characteristic for MRR is set to higher-the-better to achieve the
optimum machining productivity. Taguchi method has been used
for the construction, layout and analysis of the experiment for each
of the machining characteristic for the MRR. The use of Taguchi
method in the experiment saves a lot of time and cost of preparing
and machining the experiment samples. Therefore, an L18
Orthogonal array which was the fundamental component in the
statistical design of experiments has been used to plan the
experiments and Analysis of Variance (ANOVA) is used to
determine the optimum machining parameters for this machining
characteristic. The control parameters selected for this
optimization experiments are polarity, pulse on duration, discharge
current, discharge voltage, machining depth, machining diameter
and dielectric liquid pressure. The result had shown that the higher
the discharge voltage, the higher will be the MRR.
Abstract: The High Voltage (HV) transmission mains into the community necessitate earthing design to ensure safety compliance of the system. Concrete poles are widely used within HV transmission mains; which could have an impact on the earth grid impedance and input impedance of the system from the fault point of view. This paper provides information on concrete pole earthing to enhance the split factor of the system; further, it discusses the deployment of concrete structures in high soil resistivity area to reduce the earth grid system of the plant. This paper introduces the cut off soil resistivity SC ρ when replacing timber poles with concrete ones.
Abstract: Personnel protection devices are cardinal in safety hazard applications. They are widely used in home, office and in industry environments to reduce the risk of lethal shock to human being and equipment safety. This paper briefly reviews various personnel protection devices also describes the basic working principle of conventional ground fault circuit interrupter (GFCI) or ground fault isolator (GFI), its disadvantages and ways to overcome the disadvantages with solid-state relay (SSR) based GFI with ultrafast response up on fault implemented in printed circuit board. This solid state GFI comprises discrete MOSFET based alternating current (AC) switches, linear optical amplifier, photovoltaic isolator and sense resistor. In conventional GFI, current transformer is employed as a sensing element to detect the difference in current flow between live and neutral conductor. If there is no fault in equipment powered through GFI, due to insulation failure of internal wires and windings of motors, both live and neutral currents will be equal in magnitude and opposite in phase.
Abstract: As there are also graph methods of circuit analysis in
addition to algebraic methods, it is, in theory, clearly possible to
carry out an analysis of a whole switched circuit in two-phase
switching exclusively by the graph method as well. This article deals
with two methods of full-graph solving of switched circuits: by
transformation graphs and by two-graphs. It deals with the circuit
switched capacitors and the switched current, too. All methods are
presented in an equally detailed steps to be able to compare.
Abstract: The present study is concerned with the free
convective two dimensional flow and heat transfer, within the
framework of Boussinesq approximation, in anisotropic fluid filled
porous rectangular enclosure subjected to end-to-end temperature
difference have been investigated using Lattice Boltzmann method
fornon-Darcy flow model. Effects of the moving lid direction (top,
bottom, left, and right wall moving in the negative and positive x&ydirections),
number of moving walls (one or two opposite walls), the
sliding wall velocity, and four different constant temperatures
opposite walls cases (two surfaces are being insulated and the
twoother surfaces areimposed to be at constant hot and cold
temperature)have been conducted. The results obtained are discussed
in terms of the Nusselt number, vectors, contours, and isotherms.
Abstract: Deep Brain Stimulation or DBS is the second solution
for Parkinson's Disease. Its three parameters are: frequency, pulse
width and voltage. They must be optimized to achieve successful
treatment. Nowadays it is done clinically by neurologists and there is
not certain numerical method to detect them. The aim of this research
is to introduce simulation and modeling of Parkinson's Disease
treatment as a computational procedure to select optimum voltage.
We recorded finger tremor signals of some Parkinsonian patients
under DBS treatment at constant frequency and pulse width but
variable voltages; then, we adapted a new model to fit these data. The
optimum voltages obtained by data fitting results were the same as
neurologists- commented voltages, which means modeling can be
used as an engineering method to select optimum stimulation
voltages.
Abstract: The neural stimulation has been gaining much interest in neuromodulation research and clinical trials. For efficiency, there is a need for variable electrical stimulation such as current and voltage stimuli as well as wireless framework. In this regard, we develop the wireless neural stimulator capable of voltage and current stimuli. The system consists of ZigBee which is a wireless communication module and stimulus generator. The stimulus generator with 8-bits resolution enable both mono-polar and bi-polar waveform in voltage (-3.3~3.3V) and current(-330~330µA) stimulus mode which is controllable. The experimental results suggest that the proposed neural stimulator can play a role as an effective approach for neuromodulation.
Abstract: A new topology of unified power quality conditioner
(UPQC) is proposed for different power quality (PQ) improvement in
a three-phase four-wire (3P-4W) distribution system. For neutral
current mitigation, a star-hexagon transformer is connected in shunt
near the load along with three-leg voltage source inverters (VSIs)
based UPQC. For the mitigation of source neutral current, the uses of
passive elements are advantageous over the active compensation due
to ruggedness and less complexity of control. In addition to this, by
connecting a star-hexagon transformer for neutral current mitigation
the over all rating of the UPQC is reduced. The performance of the
proposed topology of 3P-4W UPQC is evaluated for power-factor
correction, load balancing, neutral current mitigation and mitigation
of voltage and currents harmonics. A simple control algorithm based
on Unit Vector Template (UVT) technique is used as a control
strategy of UPQC for mitigation of different PQ problems. In this
control scheme, the current/voltage control is applied over the
fundamental supply currents/voltages instead of fast changing APFs
currents/voltages, thereby reducing the computational delay.
Moreover, no extra control is required for neutral source current
compensation; hence the numbers of current sensors are reduced. The
performance of the proposed topology of UPQC is analyzed through
simulations results using MATLAB software with its Simulink and
Power System Block set toolboxes.
Abstract: Gas Metal Arc Welding (GMAW) processes is an
important joining process widely used in metal fabrication
industries. This paper addresses modeling and optimization of this
technique using a set of experimental data and regression analysis.
The set of experimental data has been used to assess the influence
of GMAW process parameters in weld bead geometry. The
process variables considered here include voltage (V); wire feed
rate (F); torch Angle (A); welding speed (S) and nozzle-to-plate
distance (D). The process output characteristics include weld bead
height, width and penetration. The Taguchi method and regression
modeling are used in order to establish the relationships between
input and output parameters. The adequacy of the model is
evaluated using analysis of variance (ANOVA) technique. In the
next stage, the proposed model is embedded into a Simulated
Annealing (SA) algorithm to optimize the GMAW process
parameters. The objective is to determine a suitable set of process
parameters that can produce desired bead geometry, considering
the ranges of the process parameters. Computational results prove
the effectiveness of the proposed model and optimization
procedure.
Abstract: in this work, we present a new strategy of direct adaptive control denoted: Extended minimal controller synthesis (EMCS). This algorithm is designed for an induction motor, which includes both electrical and mechanical dynamics under the assumptions of linear magnetic circuits. The main motivation of the EMCS control is to enhance the robustness of the MRAC algorithms, i.e. the rejection of bounded effects of rapidly varying external disturbances.
Abstract: A two-dimensional numerical simulation of crossflow
around four cylinders in an in-line rectangular configuration is
studied by using the lattice Boltzmann method (LBM). Special
attention is paid to the effect of the spacing between the cylinders.
The Reynolds number ( Re ) is chosen to be e 100 R = and the
spacing ratio L / D is set at 0.5, 1.5, 2.5, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0
and 10.0. Results show that, as in the case of four cylinders in an inline
rectangular configuration , flow fields show four different
features depending on the spacing (single square cylinder, stable
shielding flow, wiggling shielding flow and a vortex shedding flow)
are observed in this study. The effects of spacing ratio on physical
quantities such as mean drag coefficient, Strouhal number and rootmean-
square value of the drag and lift coefficients are also presented.
There is more than one shedding frequency at small spacing ratios.
The mean drag coefficients for downstream cylinders are less than
that of the single cylinder for all spacing ratios. The present results
using the LBM are compared with some existing experimental data
and numerical studies. The comparison shows that the LBM can
capture the characteristics of the bluff body flow reasonably well and
is a good tool for bluff body flow studies.
Abstract: In this paper, we show that the association of the PI
regulators for the speed and stator currents with a control strategy
using the linearization by state feedback for an induction machine
without speed sensor, and with an adaptation of the rotor resistance.
The rotor speed is estimated by using the model reference adaptive
system approach (MRAS). This method consists of using two
models: The first is the reference model and the second is an
adjustable one in which two components of the stator flux, obtained
from the measurement of the currents and stator voltages are
estimated. The estimated rotor speed is then obtained by canceling
the difference between stator-flux of the reference model and those
of the adjustable one. Satisfactory results of simulation are obtained
and discussed in this paper to highlight the proposed approach.
Abstract: Trends in business intelligence, e-commerce and
remote access make it necessary and practical to store data in
different ways on multiple systems with different operating systems.
As business evolve and grow, they require efficient computerized
solution to perform data update and to access data from diverse
enterprise business applications. The objective of this paper is to
demonstrate the capability of DTS [1] as a database solution for
automatic data transfer and update in solving business problem. This
DTS package is developed for the sales of variety of plants and
eventually expanded into commercial supply and landscaping
business. Dimension data modeling is used in DTS package to
extract, transform and load data from heterogeneous database
systems such as MySQL, Microsoft Access and Oracle that
consolidates into a Data Mart residing in SQL Server. Hence, the
data transfer from various databases is scheduled to run automatically
every quarter of the year to review the efficient sales analysis.
Therefore, DTS is absolutely an attractive solution for automatic data
transfer and update which meeting today-s business needs.
Abstract: In this article, various models of surface tension force (CSF, CSS and PCIL) for interfacial flows have been applied to dynamic case and the results were compared. We studied the Kelvin- Helmholtz instabilities, which are produced by shear at the interface between two fluids with different physical properties. The velocity inlet is defined as a sinusoidal perturbation. When gravity and surface tension are taking into account, we observe the development of the Instability for a critic value of the difference of velocity of the both fluids. The VOF Model enables to simulate Kelvin-Helmholtz Instability as dynamic case.
Abstract: This paper presents a remote on-line diagnostic system
for vehicles via the use of On-Board Diagnostic (OBD), GPS, and 3G
techniques. The main parts of the proposed system are on-board
computer, vehicle monitor server, and vehicle status browser. First,
the on-board computer can obtain the location of deriver and vehicle
status from GPS receiver and OBD interface, respectively. Then
on-board computer will connect with the vehicle monitor server
through 3G network to transmit the real time vehicle system status.
Finally, vehicle status browser could show the remote vehicle status
including vehicle speed, engine rpm, battery voltage, engine coolant
temperature, and diagnostic trouble codes. According to the
experimental results, the proposed system can help fleet managers and
car knockers to understand the remote vehicle status. Therefore this
system can decrease the time of fleet management and vehicle repair
due to the fleet managers and car knockers who find the diagnostic
trouble messages in time.
Abstract: One of the major disadvantages of the minimally
invasive surgery (MIS) is the lack of tactile feedback to the surgeon.
In order to identify and avoid any damage to the grasped complex
tissue by endoscopic graspers, it is important to measure the local
softness of tissue during MIS. One way to display the measured
softness to the surgeon is a graphical method. In this paper, a new
tactile sensor has been reported. The tactile sensor consists of an
array of four softness sensors, which are integrated into the jaws of a
modified commercial endoscopic grasper. Each individual softness
sensor consists of two piezoelectric polymer Polyvinylidene Fluoride
(PVDF) films, which are positioned below a rigid and a compliant
cylinder. The compliant cylinder is fabricated using a micro molding
technique. The combination of output voltages from PVDF films is
used to determine the softness of the grasped object. The theoretical
analysis of the sensor is also presented.
A method has been developed with the aim of reproducing the
tactile softness to the surgeon by using a graphical method. In this
approach, the proposed system, including the interfacing and the data
acquisition card, receives signals from the array of softness sensors.
After the signals are processed, the tactile information is displayed
by means of a color coding method. It is shown that the degrees of
softness of the grasped objects/tissues can be visually differentiated
and displayed on a monitor.
Abstract: Langmuir–Blodgett (LB) films of polyaniline (PANI) grown onto ITO coated glass substrates were utilized for the fabrication of Uric acid biosensor for efficient detection of uric acid by immobilizing Uricase via EDC–NHS coupling. The modified electrodes were characterized by atomic force microscopy (AFM). The response characteristics after immobilization of uricase were studied using cyclic voltammetry and electrochemical impedance spectroscopy techniques. The uricase/PANI/ITO/glass bioelectrode studied by CV and EIS techniques revealed detection of uric acid in a wide range of 0.05 mM to 1.0 mM, covering the physiological range in blood. A low Michaelis–Menten constant (Km) of 0.21 mM indicates the higher affinity of immobilized Uricase towards its analyte (uric acid). The fabricated uric acid biosensor based on PANI LB films exhibits excellent sensitivity of 0.21 mA/mM with a response time of 4 s, good reproducibility, long shelf life (8 weeks) and high selectivity.
Abstract: High voltage generators are being subject to higher
voltage rating and are being designed to operate in harsh conditions.
Stator windings are the main component of generators in which
Electrical, magnetical and thermal stresses remain major failures for
insulation degradation accelerated aging. A large number of
generators failed due to stator winding problems, mainly insulation
deterioration. Insulation degradation assessment plays vital role in the
asset life management. Mostly the stator failure is catastrophic
causing significant damage to the plant. Other than generation loss,
stator failure involves heavy repair or replacement cost. Electro
thermal analysis is the main characteristic for improvement design of
stator slot-s insulation. Dielectric parameters such as insulation
thickness, spacing, material types, geometry of winding and slot are
major design consideration. A very powerful method available to
analyze electro thermal performance is Finite Element Method
(FEM) which is used in this paper. The analysis of various stator coil
and slot configurations are used to design the better dielectric system
to reduce electrical and thermal stresses in order to increase the
power of generator in the same volume of core. This paper describes
the process used to perform classical design and improvement
analysis of stator slot-s insulation.