Abstract: The application of a Static Synchronous Series Compensator (SSSC) controller to improve the transient stability performance of a power system is thoroughly investigated in this paper. The design problem of SSSC controller is formulated as an optimization problem and Particle Swarm Optimization (PSO) Technique is employed to search for optimal controller parameters. By minimizing the time-domain based objective function, in which the deviation in the oscillatory rotor angle of the generator is involved; transient stability performance of the system is improved. The proposed controller is tested on a weakly connected power system subjected to different severe disturbances. The non-linear simulation results are presented to show the effectiveness of the proposed controller and its ability to provide efficient damping of low frequency oscillations. It is also observed that the proposed SSSC controller improves greatly the voltage profile of the system under severe disturbances.
Abstract: The original idea for a feature film may come from a
writer, director or a producer. Director is the person responsible for
the creative aspects, both interpretive and technical, of a motion
picture production in a film. Director may be shot discussing his
project with his or her cowriters, members of production staff, and
producer, and director may be shown selecting locales or
constructing sets. All these activities provide, of course, ways of
externalizing director-s ideas about the film. A director sometimes
pushes both the film image and techniques of narration to new artistic
limits, but main responsibility of director is take the spectator to an
original opinion in his philosophical approach. Director tries to find
an artistic angle in every scene and change screenplay into an
effective story and sets his film on a spiritual and philosophical base.
Abstract: Brain ArterioVenous Malformation (BAVM) is an abnormal tangle of brain blood vessels where arteries shunt directly into veins with no intervening capillary bed which causes high pressure and hemorrhage risk. The success of treatment by embolization in interventional neuroradiology is highly dependent on the accuracy of the vessels visualization. In this paper the performance of clustering techniques on vessel segmentation from 3- D rotational angiography (3DRA) images is investigated and a new technique of segmentation is proposed. This method consists in: preprocessing step of image enhancement, then K-Means (KM), Fuzzy C-Means (FCM) and Expectation Maximization (EM) clustering are used to separate vessel pixels from background and artery pixels from vein pixels when possible. A post processing step of removing false-alarm components is applied before constructing a three-dimensional volume of the vessels. The proposed method was tested on six datasets along with a medical assessment of an expert. Obtained results showed encouraging segmentations.
Abstract: Non-saturated soils that while saturation greatly
decrease their volume, have sudden settlement due to increasing
humidity, fracture and structural crack are called loess soils. Whereas
importance of civil projects including: dams, canals and
constructions bearing this type of soil and thereof problems, it is
required for carrying out more research and study in relation to loess
soils. This research studies shear strength parameters by using
grading test, Atterberg limit, compression, direct shear and
consolidation and then effect of using cement and lime additives on
stability of loess soils is studied. In related tests, lime and cement are
separately added to mixed ratios under different percentages of soil
and for different times the stabilized samples are processed and effect
of aforesaid additives on shear strength parameters of soil is studied.
Results show that upon passing time the effect of additives and
collapsible potential is greatly decreased and upon increasing
percentage of cement and lime the maximum dry density is
decreased; however, optimum humidity is increased. In addition,
liquid limit and plastic index is decreased; however, plastic index
limit is increased. It is to be noted that results of direct shear test
reveal increasing shear strength of soil due to increasing cohesion
parameter and soil friction angle.
Abstract: Telecommuting has become an increasingly popular
work arrangement. However, little research has examined the impact
of telecommuting on the relationship between employees and the
organization. This study aims to shed light on this aspect by
comparing the loyalty of telecommuters and non telecommuters as it
can be viewed from three angles: organizational loyalty, peer loyalty,
and professional loyalty. Furthermore, this paper will explore the
dynamics among employee loyalty, productivity, and job
satisfaction. Whereas previous studies had looked on employees that
are not fully telecommuting, the current study concentrates on
employees that are exclusively working from home.
Abstract: Any rotation of a 3-dimensional object can be performed by three consecutive rotations over Euler angles. Intrinsic rotations produce the same result as extrinsic rotations in transformation. Euler rotations are the movement obtained by changing one of the Euler angles while leaving the other two constant. These Euler rotations are applied in a simple two-axis gimbals set mounted on an automotives. The values of Euler angles are [π/4, π/4, π/4] radians inside the angles ranges for a given coordinate system and these actual orientations can be directly measured from these gimbals set of moving automotives but it can occur the gimbals lock in application at [π/2.24, 0, 0] radians. In order to avoid gimbals lock, the values of quaternion must be [π/4.8, π/8.2, 0, π/4.8] radians. The four-gimbals set can eliminate gimbals lock.
Abstract: This study presents an exact general solution for
steady-state conductive heat transfer in cylindrical composite
laminates. Appropriate Fourier transformation has been obtained
using Sturm-Liouville theorem. Series coefficients are achieved by
solving a set of equations that related to thermal boundary conditions
at inner and outer of the cylinder, also related to temperature
continuity and heat flux continuity between each layer. The solution
of this set of equations are obtained using Thomas algorithm. In this
paper, the effect of fibers- angle on temperature distribution of
composite laminate is investigated under general boundary
conditions. Here, we show that the temperature distribution for any
composite laminates is between temperature distribution for
laminates with θ = 0° and θ = 90° .
Abstract: There are many automotive accidents due to blind spots and driver inattentiveness. Blind spot is the area that is invisible to the driver's viewpoint without head rotation. Several methods are available for assisting the drivers. Simplest methods are — rear mirrors and wide-angle lenses. But, these methods have a disadvantage of the requirement for human assistance. So, the accuracy of these devices depends on driver. Another approach called an automated approach that makes use of sensors such as sonar or radar. These sensors are used to gather range information. The range information will be processed and used for detecting the collision. The disadvantage of this system is — low angular resolution and limited sensing volumes. This paper is a panoramic sensor based automotive vehicle monitoring..
Abstract: Based on the standard finite element method, a new
finite element method which is known as nonlocal finite element
method (NL-FEM) is numerically implemented in this article to
study the nonlocal effects for solving 1D nonlocal elastic problem.
An Eringen-type nonlocal elastic model is considered. In this model,
the constitutive stress-strain law is expressed interms of integral
equation which governs the nonlocal material behavior. The new
NL-FEM is adopted in such a way that the postulated nonlocal elastic
behavior of material is captured by a finite element endowed with a
set of (cross-stiffness) element itself by the other elements in mesh.
An example with their analytical solutions and the relevant numerical
findings for various load and boundary conditions are presented and
discussed in details. It is observed from the numerical solutions that
the torsional deformation angle decreases with increasing nonlocal
nanoscale parameter. It is also noted that the analytical solution fails
to capture the nonlocal effect in some cases where numerical
solutions handle those situation effectively which prove the
reliability and effectiveness of numerical techniques.
Abstract: The impact of fixed speed squirrel cage type as well as
variable speed doubly fed induction generators (DFIG) on dynamic
performance of a multimachine power system has been investigated.
Detailed models of the various components have been presented and
the integration of asynchronous and synchronous generators has been
carried out through a rotor angle based transform. Simulation studies
carried out considering the conventional dynamic model of squirrel
cage asynchronous generators show that integration, as such, could
degrade to the AC system performance transiently. This article
proposes a frequency or power controller which can effectively
control the transients and restore normal operation of fixed speed
induction generator quickly. Comparison of simulation results
between classical cage and doubly-fed induction generators indicate
that the doubly fed induction machine is more adaptable to
multimachine AC system. Frequency controller installed in the DFIG
system can also improve its transient profile.
Abstract: We describe a work with an evolutionary computing
algorithm for non photo–realistic rendering of a target image. The
renderings are produced by genetic programming. We have used two
different types of strokes: “empty triangle" and “filled triangle" in
color level. We compare both empty and filled triangular strokes to
find which one generates more aesthetic pleasing images. We found
the filled triangular strokes have better fitness and generate more
aesthetic images than empty triangular strokes.
Abstract: Multilevel inverters supplied from equal and constant
dc sources almost don-t exist in practical applications. The variation
of the dc sources affects the values of the switching angles required
for each specific harmonic profile, as well as increases the difficulty
of the harmonic elimination-s equations. This paper presents an
extremely fast optimal solution of harmonic elimination of multilevel
inverters with non-equal dc sources using Tanaka's fuzzy linear
regression formulation. A set of mathematical equations describing
the general output waveform of the multilevel inverter with nonequal
dc sources is formulated. Fuzzy linear regression is then
employed to compute the optimal solution set of switching angles.
Abstract: This paper present a new way to find the aerodynamic
characteristic equation of missile for the numerical trajectories
prediction more accurate. The goal is to obtain the polynomial
equation based on two missile characteristic parameters, angle of
attack (α ) and flight speed (ν ). First, the understudied missile is
modeled and used for flow computational model to compute
aerodynamic force and moment. Assume that performance range of
understudied missile where range -10< α
Abstract: This experiment was conducted in attempt of
improving hydrodynamic efficiency of the propulsion mechanism by
installing a spring to the wing so that the opening angle of the wing in
one stroke can be changed automatically, compared to the existing
method of fixed maximum opening angle in Weis-Fogh type ship
propulsion mechanism. Average thrust coefficient was almost fixed
with all velocity ratio with the prototype, but with the spring type,
thrust coefficient increased sharply as velocity ratio increased.
Average propulsive efficiency was larger with bigger opening angle in
the prototype, but in the spring type, the one with smaller spring
coefficient had larger value. In the range over 1.0 in velocity ratio
where big thrust can be generated, spring type had more than twice of
propulsive efficiency increase compared to the prototype.
Abstract: In this study the mixed mode fracture mechanics
parameters were investigated for high tensile steel butt welded joint
based on modified Arcan test and finite element analysis was used to
evaluate the effect of crack length on fracture criterion. The nondimensional
stress intensity factors, strain energy release rates and Jintegral
energy on crack tip were obtained for various in-plane
loading combinations on Arcan specimen starting from pure mode-I
to pure mode-II loading conditions. The specimen and apparatus were
modeled by finite element method and analyzed under various
loading angles (between 0 to 90 degrees with 15 degree interval) to
simulate the pure mode-I, II and mixed mode fracture. Since the
analytical results are independent from elasticity modules for
isotropic materials, therefore the results in elastic fields can be used
for Arcan specimens. The main objective of this study was to
evaluate the geometric calibration factors for modified Arcan test
specimen in order to obtain fracture toughness under mixed mode
loading conditions.
Abstract: Localized surface plasmon resonance (LSPR) is the
coherent oscillation of conductive electrons confined in noble
metallic nanoparticles excited by electromagnetic radiation, and
nanosphere lithography (NSL) is one of the cost-effective methods to
fabricate metal nanostructures for LSPR. NSL can be categorized
into two major groups: dispersed NSL and closely pack NSL. In
recent years, gold nanocrescents and gold nanoholes with vertical
sidewalls fabricated by dispersed NSL, and silver nanotriangles and
gold nanocaps on silica nanospheres fabricated by closely pack NSL,
have been reported for LSPR biosensing. This paper introduces
several novel gold nanostructures fabricated by NSL in LSPR
applications, including 3D nanostructures obtained by evaporating
gold obliquely on dispersed nanospheres, nanoholes with slant
sidewalls, and patchy nanoparticles on closely packed nanospheres,
all of which render satisfactory sensitivity for LSPR sensing. Since
the LSPR spectrum is very sensitive to the shape of the metal
nanostructures, formulas are derived and software is developed for
calculating the profiles of the obtainable metal nanostructures by
NSL, for different nanosphere masks with different fabrication
conditions. The simulated profiles coincide well with the profiles of
the fabricated gold nanostructures observed under scanning electron
microscope (SEM) and atomic force microscope (AFM), which
proves that the software is a useful tool for the process design of
different LSPR nanostructures.
Abstract: The quest for alternatefuels for a CI engine has
become all the more imperative considering its importance in the
economy of a nation and from the standpoint of preserving the environment. Reported in this paper are the combustion performance and P-θ characteristics of a CI engine operating on B20 biodiesel fuel derived from Jatropha oil.Itis observed that the twin effect of advancing the injection timing and increasing the injector opening pressure (IOP) up to 220 barhas resulted in minimum brake specific
energy consumption and higherpeak pressure. It is also observed that
the crank angle of occurrence of peak pressure progressestowards top
dead center (TDC) as the timing is advanced and IOP is increased.
Abstract: Post growth annealing of solution grown ZnO
nanowire array is performed under controlled oxygen ambience. The
role of annealing over surface defects and their consequence on
dark/photo-conductivity and photosensitivity of nanowire array is
investigated. Surface defect properties are explored using various
measurement tools such as contact angle, photoluminescence, Raman
spectroscopy and XPS measurements. The contact angle of the NW
films reduces due to oxygen annealing and nanowire film surface
changes from hydrophobic (96°) to hydrophilic (16°). Raman and
XPS spectroscopy reveal that oxygen annealing improves the crystal
quality of the nanowire films. The defect band emission intensity
(relative to band edge emission, ID/IUV) reduces from 1.3 to 0.2 after
annealing at 600 °C at 10 SCCM flow of oxygen. An order
enhancement in dark conductivity is observed in O2 annealed
samples, while photoconductivity is found to be slightly reduced due
to lower concentration of surface related oxygen defects.
Abstract: In order to improve control performance and eliminate steady, a coupling compensation for 6-DOF parallel robot is presented. Taking dynamic load Tank Simulator as the research object, this paper analyzes the coupling of 6-DOC parallel robot considering the degree of freedom of the 6-DOF parallel manipulator. The coupling angle and coupling velocity are derived based on inverse kinematics model. It uses the mechanism-model combined method which takes practical moving track that considering the performance of motion controller and motor as its input to make the study. Experimental results show that the coupling compensation improves motion stability as well as accuracy. Besides, it decreases the dither amplitude of dynamic load Tank Simulator.
Abstract: The objective of this paper is to analyze the
performance of a double-sided axial flux permanent magnet
brushless DC (AFPM BLDC) motor with two-phase winding.
To study the motor operation, a mathematical dynamic model
has been proposed for motor, which became the basis for
simulations that were performed using MATLAB/SIMULINK
software package. The results of simulations were presented
in form of the waveforms of selected quantities and the
electromechanical characteristics performed by the motor. The
calculation results show that the two-phase motor version
develops smooth torque and reaches high efficiency. The twophase
motor can be applied where more smooth torque is
required. Finally a study on the influence of switching angle
on motor performance shows that when advance switching
technique is used, the motor operates with the highest
efficiency.