Abstract: This paper presents a simple approach for load
flow analysis of a radial distribution network. The proposed
approach utilizes forward and backward sweep algorithm
based on Kirchoff-s current law (KCL) and Kirchoff-s voltage
law (KVL) for evaluating the node voltages iteratively. In this
approach, computation of branch current depends only on the
current injected at the neighbouring node and the current in
the adjacent branch. This approach starts from the end nodes
of sub lateral line, lateral line and main line and moves
towards the root node during branch current computation. The
node voltage evaluation begins from the root node and moves
towards the nodes located at the far end of the main, lateral
and sub lateral lines. The proposed approach has been tested
using four radial distribution systems of different size and
configuration and found to be computationally efficient.
Abstract: The objective of this paper is to analyse the
application of the Half-Sweep Gauss-Seidel (HSGS) method by using
the Half-sweep approximation equation based on central difference
(CD) and repeated trapezoidal (RT) formulas to solve linear fredholm
integro-differential equations of first order. The formulation and
implementation of the Full-Sweep Gauss-Seidel (FSGS) and Half-
Sweep Gauss-Seidel (HSGS) methods are also presented. The HSGS
method has been shown to rapid compared to the FSGS methods.
Some numerical tests were illustrated to show that the HSGS method
is superior to the FSGS method.
Abstract: Along with increasing development of generation of supersonic planes especially fighters and request for increasing the performance and maneuverability scientists and engineers suggested the delta and double delta wing design. One of the areas which was necessary to be researched, was the Aerodynamic review of this type of wings in high angles of attack at low speeds that was very important in landing and takeoff the planes and maneuvers. Leading Edges of the wings,cause the separation flow from wing surface and then formation of powerful vortex with high rotational speed which studing the mechanism and location of formation and also the position of the vortex breakdown in high angles of attack is very important. In this research, a double delta wing with 76o/45o sweep angles at high angle of attack in steady state and incompressible flow were numerically analyzed with Fluent software. With analaysis of the numerical results, we arrived the most important characteristic of the double delta wings which is keeping of lift at high angles of attacks.
Abstract: A multiphase harmonic load flow algorithm is developed based on backward/forward sweep to examine the effects of various factors on the neutral to earth voltage (NEV), including unsymmetrical system configuration, load unbalance and harmonic injection. The proposed algorithm composes fundamental frequency and harmonic frequencies power flows. The algorithm and the associated models are tested on IEEE 13 bus system. The magnitude of NEV is investigated under various conditions of the number of grounding rods per feeder lengths, the grounding rods resistance and the grounding resistance of the in feeding source. Additionally, the harmonic injection of nonlinear loads has been considered and its influences on NEV under different conditions are shown.
Abstract: We fabricated the inverted-staggered etch stopper
structure oxide-based TFT and investigated the characteristics of oxide
TFT under the 400 nm wavelength light illumination. When 400 nm
light was illuminated, the threshold voltage (Vth) decreased and
subthreshold slope (SS) increased at forward sweep, while Vth and SS
were not altered when larger wavelength lights, such as 650 nm, 550
nm and 450 nm, were illuminated. At reverse sweep, the transfer curve
barely changed even under 400 nm light. Our experimental results
support that photo-induced hole carriers are captured by donor-like
interface trap and it caused the decrease of Vth and increase of SS. We
investigated the interface trap density increases proportionally to the
photo-induced hole concentration at active layer.
Abstract: Shape optimization of the airfoil with high aspect ratio
of long endurance unmanned aerial vehicle (UAV) is performed by the
multi-objective optimization technology coupled with computational
fluid dynamics (CFD). For predicting the aerodynamic characteristics
around the airfoil the high-fidelity Navier-Stokes solver is employed
and SMOGA (Simple Multi-Objective Genetic Algorithm), which is
developed by authors, is used for solving the multi-objective
optimization problem. To obtain the optimal solutions of the design
variable (i.e., sectional airfoil profile, wing taper ratio and sweep) for
high performance of UAVs, both the lift and lift-to-drag ratio are
maximized whereas the pitching moment should be minimized,
simultaneously. It is found that the lift force and lift-to-drag ratio are
linearly dependent and a unique and dominant solution are existed.
However, a trade-off phenomenon is observed between the lift-to-drag
ratio and pitching moment. As the result of optimization, sixty-five
(65) non-dominated Pareto individuals at the cutting edge of design
spaces that is decided by airfoil shapes can be obtained.
Abstract: This paper describes an application of a dual satellite
geolocation (DSG) system on identifying and locating the unknown
source of uplink sweeping interference. The geolocation system
integrates the method of joint time difference of arrival (TDOA) and
frequency difference of arrival (FDOA) with ephemeris correction
technique which successfully demonstrated high accuracy in
interference source location. The factors affecting the location error
were also discussed.
Abstract: This paper describes a computer-aided design for
design of the concave globoidal cam with cylindrical rollers and
swinging follower. Four models with different modeling methods are
made from the same input data. The input data are angular input and
output displacements of the cam and the follower and some other
geometrical parameters of the globoidal cam mechanism. The best
cam model is the cam which has no interference with the rollers
when their motions are simulated in assembly conditions. The
angular output displacement of the follower for the best cam is also
compared with that of in the input data to check errors. In this study,
Pro/ENGINEER® Wildfire 2.0 is used for modeling the cam,
simulating motions and checking interference and errors of the
system.
Abstract: Power transformer consists of components which are
under consistent thermal and electrical stresses. The major
component which degrades under these stresses is the paper
insulation of the power transformer. At site, lightning impulses and
cable faults may cause the winding deformation. In addition, the
winding may deform due to impact during transportation. A
deformed winding will excite more stress to its insulating paper thus
will degrade it. Insulation degradation will shorten the life-span of
the transformer. Currently there are two methods of detecting the
winding deformation which are Sweep Frequency Response
Analysis (SFRA) and Low Voltage Impulse Test (LVI). The latter
injects current pulses to the winding and capture the admittance
plot. In this paper, a transformer which experienced overheating and
arcing was identified, and both SFRA and LVI were performed.
Next, the transformer was brought to the factory for untanking. The
untanking results revealed that the LVI is more accurate than the
SFRA method for this case study.
Abstract: This paper deals with a novel approach of power
transformers diagnostics. This approach identifies the exact location
and the range of a fault in the transformer and helps to reduce
operation costs related to handling of the faulty transformer, its
disassembly and repair. The advantage of the approach is a
possibility to simulate healthy transformer and also all faults, which
can occur in transformer during its operation without its
disassembling, which is very expensive in practice. The approach is
based on creating frequency dependent impedance of the transformer
by sweep frequency response analysis measurements and by 3D FE
parametrical modeling of the fault in the transformer. The parameters
of the 3D FE model are the position and the range of the axial short
circuit. Then, by comparing the frequency dependent impedances of
the parametrical models with the measured ones, the location and the
range of the fault is identified. The approach was tested on a real
transformer and showed high coincidence between the real fault and
the simulated one.
Abstract: The hand is one of the essential parts of the body for
carrying out Activities of Daily Living (ADLs). Individuals use their
hands and fingers in everyday activities in the both the workplace
and home. Hand-intensive tasks require diverse and sometimes
extreme levels of exertion, depending on the action, movement or
manipulation involved. The authors have undertaken several studies
looking at grip choice and comfort. It is hoped that in providing
improved understanding of discomfort during ADLs this will aid in
the design of consumer products.
Previous work by the authors outlined a methodology for
calculating pain frequency and pain level for a range of tasks. From
an online survey undertaken by the authors with regards
manipulating objects during everyday tasks, tasks involving
gripping were seen to produce the highest levels of pain and
discomfort. Questioning of the participants showed that cleaning
tasks were seen to be ADL's that produced the highest levels of
discomfort, with women feeling higher levels of discomfort than
men.
This paper looks at the methodology for calculating pain
frequency and pain level with particular regards to gripping
activities. This methodology shows that activities such as mopping,
sweeping and hoovering shows the highest numbers of pain
frequency and pain level at 3112.5 frequency per month while the
pain level per person doing this action was 0.78.The study then uses
thin-film force sensors to analyze the force distribution in the hand
whilst hoovering and compares this for differing grip styles and
genders. Women were seen to have more of their hand under a
higher pressure than men when undertaking hoovering. This
suggests that women may feel greater discomfort than men since
their hand is at a higher pressure more of the time.