Abstract: Solid fuel transient burning behavior under oxidizer
gas flow is numerically investigated. It is done using analysis of the
regression rate responses to the imposed sudden and oscillatory
variation at inflow properties. The conjugate problem is considered
by simultaneous solution of flow and solid phase governing
equations to compute the fuel regression rate. The advection
upstream splitting method is used as flow computational scheme in
finite volume method. The ignition phase is completely simulated to
obtain the exact initial condition for response analysis. The results
show that the transient burning effects which lead to the combustion
instabilities and intermittent extinctions could be observed in solid
fuels as the solid propellants.
Abstract: Iterative learning control aims to achieve zero tracking
error of a specific command. This is accomplished by iteratively
adjusting the command given to a feedback control system, based on
the tracking error observed in the previous iteration. One would like
the iterations to converge to zero tracking error in spite of any error
present in the model used to design the learning law. First, this need
for stability robustness is discussed, and then the need for robustness
of the property that the transients are well behaved. Methods of
producing the needed robustness to parameter variations and to
singular perturbations are presented. Then a method involving
reverse time runs is given that lets the world behavior produce the
ILC gains in such a way as to eliminate the need for a mathematical
model. Since the real world is producing the gains, there is no issue
of model error. Provided the world behaves linearly, the approach
gives an ILC law with both stability robustness and good transient
robustness, without the need to generate a model.
Abstract: Transient shape variation of a rotating liquid dropletis
simulated numerically. The three dimensional Navier-Stokes
equations were solved by using the level set method. The shape
variation from the sphere to the rotating ellipsoid, and to the two-robed
shapeare simulated, and the elongation of the two-robed droplet is
discussed. The two-robed shape after the initial transient is found to be
stable and the elongation is almost the same for the cases with different
initial rotation rate. The relationship between the elongation and the
rotation rate is obtained by averaging the transient shape variation. It is
shown that the elongation of two-robed shape is in good agreement
with the existing experimental data. It is found that the transient
numerical simulation is necessary for analyzing the largely elongated
two-robed shape of rotating droplet.
Abstract: Electrical distribution systems are incurring large losses as the loads are wide spread, inadequate reactive power compensation facilities and their improper control. A comprehensive static VAR compensator consisting of capacitor bank in five binary sequential steps in conjunction with a thyristor controlled reactor of smallest step size is employed in the investigative work. The work deals with the performance evaluation through analytical studies and practical implementation on an existing system. A fast acting error adaptive controller is developed suitable both for contactor and thyristor switched capacitors. The switching operations achieved are transient free, practically no need to provide inrush current limiting reactors, TCR size minimum providing small percentages of nontriplen harmonics, facilitates stepless variation of reactive power depending on load requirement so as maintain power factor near unity always. It is elegant, closed loop microcontroller system having the features of self regulation in adaptive mode for automatic adjustment. It is successfully tested on a distribution transformer of three phase 50 Hz, Dy11, 11KV/440V, 125 KVA capacity and the functional feasibility and technical soundness are established. The controller developed is new, adaptable to both LT & HT systems and practically established to be giving reliable performance.
Abstract: In this paper a three dimensional thermal model of a
sliding contact system is proposed for both steady-state or transient
conditions. The influence of contact force, electric current and
ambient temperature on the temperature distribution, has been
investigated. A thermal analysis of the different type of the graphite
material of fixed electric contact and its influence on contact system
temperature rise, has been performed. To validate the three
dimensional thermal model, some experimental tests have been done.
There is a good correlation between experimental and simulation
results.
Abstract: In this paper, a numerical study has been made to
analyze the transient 2-D flows of a viscous incompressible fluid
through channels with forward or backward constriction. Problems
addressed include flow through sudden contraction and sudden
expansion channel geometries with rounded and increasingly sharp
reentrant corner. In both the cases, numerical results are presented for
the separation and reattachment points, streamlines, vorticity and
flow patterns. A fourth order accurate compact scheme has been
employed to efficiently capture steady state solutions of the
governing equations. It appears from our study that sharpness of the
throat in the channel is one of the important parameters to control the
strength and size of the separation zone without modifying the
general flow patterns. The comparison between the two cases shows
that the upstream geometry plays a significant role on vortex growth
dynamics.
Abstract: It is very important to determine reference temperature when convective temperature because it should be used to calculate the temperature potential. This paper deals with the development of a new method that can determine heat transfer coefficient and reference free stream temperature simultaneously, based on transient heat transfer experiments with using two narrow band thermo-tropic liquid crystals (TLC's). The method is validated through error analysis in terms of the random uncertainties in the measured temperatures. It is shown how the uncertainties in heat transfer coefficient and free stream temperature can be reduced. The general method described in this paper is applicable to many heat transfer models with unknown free stream temperature.
Abstract: This paper reviews the optimization available
transmission capability (ATC) of power systems using a device of
FACTS named SSSC equipped with energy storage devices. So that,
emplacement and improvement of parameters of SSSC will be
illustrated. Thus, voltage magnitude constraints of network buses,
line transient stability constraints and voltage breakdown constraints
are considered. To help the calculations, a comprehensive program in
DELPHI is provided, which is able to simulate and trace the
parameters of SSSC has been installed on a specific line.
Furthermore, the provided program is able to compute ATC, TTC
and maximum value of their enhancement after using SSSC.
Abstract: Static Var Compensator (SVC) is a shunt type FACTS
device which is used in power system primarily for the purpose of
voltage and reactive power control. In this paper, a fuzzy logic based
supplementary controller for Static Var Compensator (SVC) is
developed which is used for damping the rotor angle oscillations and
to improve the transient stability of the power system. Generator
speed and the electrical power are chosen as input signals for the
Fuzzy Logic Controller (FLC). The effectiveness and feasibility of
the proposed control is demonstrated with Single Machine Infinite
Bus (SMIB) system and multimachine system (WSCC System)
which show improvement over the use of a fixed parameter
controller.
Abstract: The mechanical behavior of porous media is governed by the interaction between its solid skeleton and the fluid existing inside its pores. The interaction occurs through the interface of gains and fluid. The traditional analysis methods of porous media, based on the effective stress and Darcy's law, are unable to account for these interactions. For an accurate analysis, the porous media is represented in a fluid-filled porous solid on the basis of the Biot theory of wave propagation in poroelastic media. In Biot formulation, the equations of motion of the soil mixture are coupled with the global mass balance equations to describe the realistic behavior of porous media. Because of irregular geometry, the domain is generally treated as an assemblage of fmite elements. In this investigation, the numerical formulation for the field equations governing the dynamic response of fluid-saturated porous media is analyzed and employed for the study of transient wave motion. A finite element model is developed and implemented into a computer code called DYNAPM for dynamic analysis of porous media. The weighted residual method with 8-node elements is used for developing of a finite element model and the analysis is carried out in the time domain considering the dynamic excitation and gravity loading. Newmark time integration scheme is developed to solve the time-discretized equations which are an unconditionally stable implicit method Finally, some numerical examples are presented to show the accuracy and capability of developed model for a wide variety of behaviors of porous media.
Abstract: This paper describes a three-dimensional thermal
model of the current path included in the low voltage power circuit
breakers. The model can be used to analyse the thermal behaviour of
the current path during both steady-state and transient conditions.
The current path lengthwise temperature distribution and timecurrent
characteristic of the terminal connections of the power circuit
breaker have been obtained. The influence of the electric current and
voltage drop on main electric contact of the circuit breaker has been
investigated. To validate the three-dimensional thermal model, some
experimental tests have been done. There is a good correlation
between experimental and simulation results.
Abstract: This paper introduces a high-gain observer based state of charge(SOC) estimator for lithium-Ion batteries. The proposed SOC estimator has a high-gain observer(HGO) structure. The HGO scheme enhances the transient response speed and diminishes the effect of uncertainties. Furthermore, it guarantees that the output feedback controller recovers the performance of the state feedback controller when the observer gain is sufficiently high. In order to show the effectiveness of the proposed method, the linear RC battery model in ADVISOR is used. The performance of the proposed method is compared with that of the conventional linear observer(CLO) and some simulation result is given.
Abstract: A transient heat transfer mathematical model for the
prediction of temperature distribution in the car body during primer
baking has been developed by considering the thermal radiation and
convection in the furnace chamber and transient heat conduction
governing equations in the car framework. The car cockpit is
considered like a structure with six flat plates, four vertical plates
representing the car doors and the rear and front panels. The other
two flat plates are the car roof and floor. The transient heat
conduction in each flat plate is modeled by the lumped capacitance
method. Comparison with the experimental data shows that the heat
transfer model works well for the prediction of thermal behavior of
the car body in the curing furnace, with deviations below 5%.
Abstract: The transient analysis of a queuing system with fixed-size batch Poisson arrivals and a single server with exponential service times is presented. The focus of the paper is on the use of the functions that arise in the analysis of the transient behaviour of the queuing system. These functions are shown to be a generalization of the modified Bessel functions of the first kind, with the batch size B as the generalizing parameter. Results for the case of single-packet arrivals are obtained first. The similarities between the two families of functions are then used to obtain results for the general case of batch arrival queue with a batch size larger than one.
Abstract: In a wind power generator using doubly fed induction
generator (DFIG), the three-phase pulse width modulation (PWM)
voltage source converter (VSC) is used as grid side converter (GSC)
and rotor side converter (RSC). The standard linear control laws
proposed for GSC provides not only instablity against comparatively
large-signal disturbances, but also the problem of stability due to
uncertainty of load and variations in parameters. In this paper, a
nonlinear controller is designed for grid side converter (GSC) of a
DFIG for wind power application. The nonlinear controller is
designed based on the input-output feedback linearization control
method. The resulting closed-loop system ensures a sufficient
stability region, make robust to variations in circuit parameters and
also exhibits good transient response. Computer simulations and
experimental results are presented to confirm the effectiveness of the
proposed control strategy.
Abstract: The liquid cargo contained in a partly-filled road tank
vehicle is prone to dynamic slosh movement when subjected to
external disturbances. The slosh behavior has been identified as a
significant factor impairing the safety of liquid cargo transportation.
The laboratory experiments have been conducted for analyzing fluid
slosh in partly filled tanks. The experiment results measured under
forced harmonic excitations reveal the three-dimensional nature of
the fluid motion and coupling between the lateral and longitudinal
fluid slosh at resonance. Several spectral components are observed
for the transient slosh forces, which can be associated with the
excitation, resonance, and beat frequencies. The peak slosh forces
and moments in the vicinity of resonance are significantly larger than
those of the equivalent rigid mass. Due to the nature of coupling
between sloshing fluid and vehicle body, the issue of the dynamic
fluid-structure interaction is essential in the analysis of tank-vehicle
dynamics. A dynamic pitch plane model of a Tridem truck
incorporated the fluid slosh dynamics is developed to analyze the
fluid-vehicle interaction under the straight-line braking maneuvers.
The results show that the vehicle responses are highly associated
with the characteristics of fluid slosh force and moment.
Abstract: This paper introduces a new approach for the performance
analysis of adaptive filter with error saturation nonlinearity in
the presence of impulsive noise. The performance analysis of adaptive
filters includes both transient analysis which shows that how fast
a filter learns and the steady-state analysis gives how well a filter
learns. The recursive expressions for mean-square deviation(MSD)
and excess mean-square error(EMSE) are derived based on weighted
energy conservation arguments which provide the transient behavior
of the adaptive algorithm. The steady-state analysis for co-related
input regressor data is analyzed, so this approach leads to a new
performance results without restricting the input regression data to
be white.
Abstract: The cDNA encoding the 326 amino acids of a Class I
basic chitinase gene from Leucaena leucocephala de Wit (KB3,
Genbank accession: AAM49597) was cloned under the control of
CaMV35S promoter in pCAMBIA 1300 and transferred to
Koshihikari. Calli of Koshihikari rice was transformed with
agrobacterium with this construct expressing the chitinase and β-
glucouronidase (GUS). The frequencies of calli 90 % has been
obtained from rice seedlings cultured on NB medium. The high
regeneration frequencies, 74% was obtained from calli cultured on
regeneration medium containing 4 mg/l BAP, and 7 g/l phytagel at
25°C. Various factors were studied in order to establish a procedure
for the transformation of Koshihikari Agrobacterium tumefaciens.
Supplementation of 50 mM acetosyringone to the medium during
coculivation was important to enhance the frequency to transient
transformation. The 4 week-old scutellum-derived calli were
excellent starting materials. Selection medium based on NB medium
supplement with 40 mg/l hygromycin and 400 mg/l cefotaxime were
an optimized medium for selection of transformed rice calli. The
percentage of transformation 70 was obtained. Recombinant calli and
regenerated rice plants were checked the expression of chitinase and
gus by PCR, northern blot gel, southern blot gel, and gus assay.
Chitinase and gus were expressed in all parts of recombinant rice.
The rice line expressing the KB3 chiitnase was more resistant to the
blast fungus Fusarium monoliforme than control line.
Abstract: Recently, genetic algorithms (GA) and particle swarm optimization (PSO) technique have attracted considerable attention among various modern heuristic optimization techniques. The GA has been popular in academia and the industry mainly because of its intuitiveness, ease of implementation, and the ability to effectively solve highly non-linear, mixed integer optimization problems that are typical of complex engineering systems. PSO technique is a relatively recent heuristic search method whose mechanics are inspired by the swarming or collaborative behavior of biological populations. In this paper both PSO and GA optimization are employed for finding stable reduced order models of single-input- single-output large-scale linear systems. Both the techniques guarantee stability of reduced order model if the original high order model is stable. PSO method is based on the minimization of the Integral Squared Error (ISE) between the transient responses of original higher order model and the reduced order model pertaining to a unit step input. Both the methods are illustrated through numerical example from literature and the results are compared with recently published conventional model reduction technique.
Abstract: The authors present an algorithm for order reduction of linear dynamic systems using the combined advantages of stability equation method and the error minimization by Genetic algorithm. The denominator of the reduced order model is obtained by the stability equation method and the numerator terms of the lower order transfer function are determined by minimizing the integral square error between the transient responses of original and reduced order models using Genetic algorithm. The reduction procedure is simple and computer oriented. It is shown that the algorithm has several advantages, e.g. the reduced order models retain the steady-state value and stability of the original system. The proposed algorithm has also been extended for the order reduction of linear multivariable systems. Two numerical examples are solved to illustrate the superiority of the algorithm over some existing ones including one example of multivariable system.