Abstract: A numbers of important developments have led to an
increasing attractiveness for very high speed electrical machines
(either motor or generator). Specifically the increasing switching
speed of power electronics, high energy magnets, high strength
retaining materials, better high speed bearings and improvements in
design analysis are the primary drivers in a move to higher speed. The
design challenges come in the mechanical design both in terms of
strength and resonant modes and in the electromagnetic design
particularly in respect of iron losses and ac losses in the various
conducting parts including the rotor. This paper describes detailed
design work which has been done on a 50,000 rpm, 50kW permanent
magnet( PM) synchronous machine. It describes work on
electromagnetic and rotor eddy current losses using a variety of
methods including both 2D finite element analysis
Abstract: Various solar energy technologies exist and they have
different application techniques in the generation of electrical power.
The widespread use of photovoltaic (PV) modules in such
technologies has been limited by relatively high costs and low
efficiencies. The efficiency of PV panels decreases as the operating
temperatures increase. This is due to the affect of solar intensity and
ambient temperature. In this work, Computational Fluid Dynamics
(CFD) was used to model the heat transfer from a standard PV panel
and thus determine the rate of dissipation of heat. To accurately
model the specific climatic conditions of the United Arab Emirates
(UAE), a case study of a new build green building in Dubai was
used. A finned heat pipe arrangement is proposed and analyzed to
determine the improved heat dissipation and thus improved
performance efficiency of the PV panel. A prototype of the
arrangement is built for experimental testing to validate the CFD
modeling and proof of concept.
Abstract: In this paper, design, fabrication and coupled
multifield analysis of hollow out-of-plane silicon microneedle array
with piezoelectrically actuated microfluidic device for transdermal
drug delivery (TDD) applications is presented. The fabrication
process of silicon microneedle array is first done by series of
combined isotropic and anisotropic etching processes using
inductively coupled plasma (ICP) etching technology. Then coupled
multifield analysis of MEMS based piezoelectrically actuated device
with integrated 2×2 silicon microneedle array is presented. To predict
the stress distribution and model fluid flow in coupled field analysis,
finite element (FE) and computational fluid dynamic (CFD) analysis
using ANSYS rather than analytical systems has been performed.
Static analysis and transient CFD analysis were performed to predict
the fluid flow through the microneedle array. The inlet pressure from
10 kPa to 150 kPa was considered for static CFD analysis. In the
lumen region fluid flow rate 3.2946 μL/min is obtained at 150 V for
2×2 microneedle array. In the present study the authors have
performed simulation of structural, piezoelectric and CFD analysis
on three dimensional model of the piezoelectrically actuated
mcirofluidic device integrated with 2×2 microneedle array.
Abstract: Capital structure is one of the most important financial
decisions in corporate financing strategy. It involves the choice of
debt and equity level in financing a company-s operations. This study
aims to investigate whether the capital structure choice of Malaysian
electrical and electronic manufacturing companies that are listed in
the Bursa Malaysia can be explained by factors that have been found
by most studies as dominant determinants of capital structure
(company size, profitability, asset tangibility, liquidity and growth).
Using debt ratio as the proxy for capital structure and applying
pooled ordinary least square multiple regression estimation, the
results showed that on average, Malaysian electrical and electronic
manufacturing companies used less debt in funding their business
operations. The findings also showed that size and asset tangibility
has a significant positive relationship with debt level, while liquidity
has a negative significant relationship with leverage.
Abstract: The load flow study in a power system constitutes a study of paramount importance. The study reveals the electrical performance and power flows (real and reactive) for specified condition when the system is operating under steady state. This paper gives an overview of different techniques used for load flow study under different specified conditions.
Abstract: A unique combination of adsorption and
electrochemical regeneration with a proprietary adsorbent material
called Nyex 100 was introduced at the University of Manchester for
waste water treatment applications. Nyex 100 is based on graphite
intercalation compound. It is non porous and electrically conducing
adsorbent material. This material exhibited very small BET surface
area i.e. 2.75 m2g-1, in consequence, small adsorptive capacities for
the adsorption of various organic pollutants were obtained. This work
aims to develop composite adsorbent material essentially capable of
electrochemical regeneration coupled with improved adsorption
characteristics. An organic dye, acid violet 17 was used as standard
organic pollutant. The developed composite material was
successfully electrochemically regenerated using a DC current of 1 A
for 60 minutes. Regeneration efficiency was maintained at around
100% for five adsorption-regeneration cycles.
Abstract: This paper discusses a genetic algorithm (GA) based optimal load shedding that can apply for electrical distribution networks with and without dispersed generators (DG). Also, the proposed method has the ability for considering constant and variable capacity deficiency caused by unscheduled outages in the bulked generation and transmission system of bulked power supply. The genetic algorithm (GA) is employed to search for the optimal load shedding strategy in distribution networks considering DGs in two cases of constant and variable modelling of bulked power supply of distribution networks. Electrical power distribution systems have a radial network and unidirectional power flows. With the advent of dispersed generations, the electrical distribution system has a locally looped network and bidirectional power flows. Therefore, installed DG in the electrical distribution systems can cause operational problems and impact on existing operational schemes. Introduction of DGs in electrical distribution systems has introduced many new issues in operational and planning level. Load shedding as one of operational issue has no exempt. The objective is to minimize the sum of curtailed load and also system losses within the frame-work of system operational and security constraints. The proposed method is tested on a radial distribution system with 33 load points for more practical applications.
Abstract: The breakdown strength characteristic of Low Density
Polyethylene films (LDPE) under DC voltage application and the
effect of water absorption have been studied. Mainly, our experiment
was investigated under two conditions; dry and heavy water
absorption. Under DC ramp voltage, the result found that the
breakdown strength under heavy water absorption has a lower value
than dry condition. In order to clarify the effect, the temperature rise of
film was observed using non contact thermograph until the occurrence
of the electrical breakdown and the conduction current of the sample
was also measured in correlation with the thermograph measurement.
From the observations, it was shown that under the heavy water
absorption, the hot spot in the samples appeared at lower voltage. At
the same voltage the temperature of the hot spot and conduction
current was higher than that under the dry condition. The measurement
result has a good correlation between the existence of a critical field
for conduction current and thermograph observation. In case of the
heavy water absorption, the occurrence of the threshold field was
earlier than the dry condition as result lead to higher of conduction
current and the temperature rise appears after threshold field was
significantly increased in increasing of field. The higher temperature
rise was caused by the higher current conduction as the result the
insulation leads to breakdown to the lower field application.
Abstract: Vermicomposting is the conversion of organic waste
into bio-fertilizers through the action of earthworm. This technology
is widely used for organic solid waste management. Waste corn pulp
blended with cow dung manure was vermicomposted over 30 days
using Eisenia fetida earthworms species. pH, temperature, moisture
content, and electrical conductivity were daily monitored. The
feedstock, vermicompost and vermiwash were analyzed for nutrient
composition. The average temperature and moisture content in the
vermi-reactor was 22.5°C and 42.5% respectively. The vermicompost
and vermiwash had an almost neutral pH whilst the electrical
conductivity was 21% higher in the vermicompost. The nitrogen and
potassium content was 57% and 79.6% richer in the vermicompost
respectively compared to the vermiwash. However, the vermiwash
was 84% richer in phosphorous as compared to vermicompost.
Furthermore, the vermiwash was 89.1% and 97.6% richer in Ca and
Mg respectively and was 97.8% richer in Na salts compared to the
vermicompost. The vermiwash also indicated a significantly higher
amount of micronutrients. Both bio-fertilizers were rich in nutrients
specification for fertilizers.
Abstract: The ferroelectric behavior of barium strontium
titanate (BST) in thin film form has been investigated in order to
study the possibility of using BST for ferroelectric gate-field effect
transistor (FeFET) for memory devices application. BST thin films
have been fabricated as Al/BST/Pt/SiO2/Si-gate configuration. The
variation of the dielectric constant (ε) and tan δ with frequency have
been studied to ensure the dielectric quality of the material. The
results show that at low frequencies, ε increases as the Ba content
increases, whereas at high frequencies, it shows the opposite
variation, which is attributed to the dipole dynamics. tan δ shows low
values with a peak at the mid-frequency range. The ferroelectric
behavior of the Al/BST/Pt/SiO2/Si has been investigated using C-V
characteristics. The results show that the strength of the ferroelectric
hysteresis loop increases as the Ba content increases; this is attributed
to the grain size and dipole dynamics effect.
Abstract: In this paper, we propose a novel metal oxide
semiconductor field effect transistor with L-shaped channel structure
(LMOS), and several type of L-shaped structures are also designed,
studied and compared with the conventional MOSFET device for the
same average gate length (Lavg). The proposed device electrical
characteristics are analyzed and evaluated by three dimension (3-D)
ISE-TCAD simulator. It can be confirmed that the LMOS devices
have higher on-state drain current and both lower drain-induced
barrier lowering (DIBL) and subthreshold swing (S.S.) than its
conventional counterpart has. In addition, the transconductance and
voltage gain properties of the LMOS are also improved.
Abstract: Recently, distributed generation technologies have received much attention for the potential energy savings and reliability assurances that might be achieved as a result of their widespread adoption. Fueling the attention have been the possibilities of international agreements to reduce greenhouse gas emissions, electricity sector restructuring, high power reliability requirements for certain activities, and concern about easing transmission and distribution capacity bottlenecks and congestion. So it is necessary that impact of these kinds of generators on distribution feeder reconfiguration would be investigated. This paper presents an approach for distribution reconfiguration considering Distributed Generators (DGs). The objective function is summation of electrical power losses A Tabu search optimization is used to solve the optimal operation problem. The approach is tested on a real distribution feeder.
Abstract: This study investigates a voltage-controllable liquid crystals lens with a Fresnel zone electrode. When applying a proper voltage on the liquid crystal cell, a Fresnel-zone-distributed electric field is induced to direct liquid crystals aligned in a concentric structure. Owing to the concentrically aligned liquid crystals, a Fresnel lens is formed. We probe the Fresnel liquid crystal lens using a polarized incident beam with a wavelength of 632.8 nm, finding that the diffraction efficiency depends on the applying voltage. A remarkable diffraction efficiency of ~39.5 % is measured at the voltage of 0.9V. Additionally, a dual focus lens is fabricated by attaching a plane-convex lens to the Fresnel liquid crystals cell. The Fresnel LC lens and the dual focus lens may be applied for DVD/CD pick-up head, confocal microscopy system, or electrically-controlling optical systems.
Abstract: The condition of lightning surge causes the traveling waves and the temporary increase in voltage in the transmission line system. Lightning is the most harmful for destroying the transmission line and setting devices so it is necessary to study and analyze the temporary increase in voltage for designing and setting the surge arrester. This analysis describes the figure of the lightning wave in transmission line with 115 kV voltage level in Thailand by using ATP/EMTP program to create the model of the transmission line and lightning surge. Because of the limit of this program, it must be calculated for the geometry of the transmission line and surge parameter and calculation in the manual book for the closest value of the parameter. On the other hand, for the effects on surge protector when the lightning comes, the surge arrester model must be right and standardized as metropolitan electrical authority's standard. The candidate compared the real information to the result from calculation, also. The results of the analysis show that the temporary increase in voltage value will be rise to 326.59 kV at the line which is done by lightning when the surge arrester is not set in the system. On the other hand, the temporary increase in voltage value will be 182.83 kV at the line which is done by lightning when the surge arrester is set in the system and the period of the traveling wave is reduced, also. The distance for setting the surge arrester must be as near to the transformer as possible. Moreover, it is necessary to know the right distance for setting the surge arrester and the size of the surge arrester for preventing the temporary increase in voltage, effectively.
Abstract: One way for optimum loading of overdimensioning
conveyers is speed (capacity) decrement, with attention for
production capabilities and demands. At conveyers which drives with
three phase slip-ring induction motor, technically reasonable solution
for conveyer (driving motors) speed regulation is using constant
torque subsynchronous cascade with static semiconductor converter
and transformer for energy reversion to the power network. In the
paper is described mathematical model for parameter calculation of
two-motors 6 kV subsynchronous cascade. It is also demonstrated
that applying of this cascade gave several good properties, foremost
in electrical energy saving, also in improving of other energy
indexes, and finally that results in cost reduction of complete
electrical motor drive.
Abstract: This study investigates the electrical performance of a
planar solid oxide fuel cell unit with cross-flow configuration when the fuel utilization gets higher and the fuel inlet flow are non-uniform.
A software package in this study solves two-dimensional,
simultaneous, partial differential equations of mass, energy, and
electro-chemistry, without considering stack direction variation. The
results show that the fuel utilization increases with a decrease in the molar flow rate, and the average current density decreases when the
molar flow rate drops. In addition, non-uniform Pattern A will induce more severe happening of non-reaction area in the corner of the fuel
exit and the air inlet. This non-reaction area deteriorates the average
current density and then deteriorates the electrical performance to –7%.
Abstract: Lighting upgrades involve relatively lower costs which
allow the benefits to be spread more widely than is possible with any
other energy efficiency measure. In order to popularize the adoption of
CFL in Taiwan, the authority proposes to implement a new energy efficient lamp comparative label system. The current study was
accordingly undertaken to investigate the factors affecting the performance and the deviation of actual and labeled performance of
commercially available integrated CFLs. In this paper, standard test
methods to determine the electrical and photometric performances of
CFL were developed based on CIE 84-1989 and CIE 60901-1987,
then 55 selected CFLs from market were tested. The results show that
with higher color temperature of CFLs lower efficacy are achieved. It
was noticed that the most packaging of CFL often lack the information of Color Rendering Index. Also, there was no correlation between
price and performance of the CFLs was indicated in this work. The results of this paper might help consumers to make more informed
CFL-purchasing decisions.
Abstract: Consumer electronics are pervasive. It is impossible to
imagine a household or office without DVD players, digital cameras,
printers, mobile phones, shavers, electrical toothbrushes, etc. All
these devices operate at different voltage levels ranging from 1.8 to
20 VDC, in the absence of universal standards. The voltages
available are however usually 120/230 VAC at 50/60 Hz. This
situation makes an individual electrical energy conversion system
necessary for each device. Such converters usually involve several
conversion stages and often operate with excessive losses and poor
reliability. The aim of the project presented in this paper is to design
and implement a multi-channel DC/DC converter system,
customizing the output voltage and current ratings according to the
requirements of the load. Distributed, multi-agent techniques will be
applied for the control of the DC/DC converters.
Abstract: We evaluated the effect of sensory (direct current
(DC), 600μA) and motor (monophasic current, pulse duration 300μs,
100 Hz, 2.5-3mA) intensities of cathodal electrical stimulation (ES)
current to release VEGF and biomechanical properties of wound. 54
male Sprague-dawley rats were randomly assigned into one control
and two experimental groups. A full thickness skin incision was
made on animals- dorsal region. The experimental groups received
ES for 1h/day and every other day. VEGF expression was measured
in skin on the 7th day after surgical incision and tensile strength was
measured on 21st day. On the 7th day, the values of skin VEGF in the
sensory group were significantly greater than those of the other
groups (p < 0.05). Sensory and Motor intensity stimulation, can not
improve the biomechanical properties of the repaired wounds.
It seems the mechanical environment induced by sensory and
motor intensity of electrical stimulation, could not simulate the role
of normal daily stress and strain to maturation of collagen fibers and
their cross links. Further work is needed to determine the relationship
between VEGF expression after ES and its effect on tensile strength
of healed wound.
Abstract: The mineral having chemical compositional formula MgAl2O4 is called “spinel". The ferrites crystallize in spinel structure are known as spinel-ferrites or ferro-spinels. The spinel structure has a fcc cage of oxygen ions and the metallic cations are distributed among tetrahedral (A) and octahedral (B) interstitial voids (sites). The X-ray diffraction (XRD) intensity of each Bragg plane is sensitive to the distribution of cations in the interstitial voids of the spinel lattice. This leads to the method of determination of distribution of cations in the spinel oxides through XRD intensity analysis. The computer program for XRD intensity analysis has been developed in C language and also tested for the real experimental situation by synthesizing the spinel ferrite materials Mg0.6Zn0.4AlxFe2- xO4 and characterized them by X-ray diffractometry. The compositions of Mg0.6Zn0.4AlxFe2-xO4(x = 0.0 to 0.6) ferrites have been prepared by ceramic method and powder X-ray diffraction patterns were recorded. Thus, the authenticity of the program is checked by comparing the theoretically calculated data using computer simulation with the experimental ones. Further, the deduced cation distributions were used to fit the magnetization data using Localized canting of spins approach to explain the “recovery" of collinear spin structure due to Al3+ - substitution in Mg-Zn ferrites which is the case if A-site magnetic dilution and non-collinear spin structure. Since the distribution of cations in the spinel ferrites plays a very important role with regard to their electrical and magnetic properties, it is essential to determine the cation distribution in spinel lattice.