Abstract: The paper examines the performance of bit-interleaved parity (BIP) methods in error rate monitoring, and in declaration and clearing of alarms in those transport networks that employ automatic protection switching (APS). The BIP-based error rate monitoring is attractive for its simplicity and ease of implementation. The BIP-based results are compared with exact results and are found to declare the alarms too late, and to clear the alarms too early. It is concluded that the standards development and systems implementation should take into account the fact of early clearing and late declaration of alarms. The window parameters defining the detection and clearing thresholds should be set so as to build sufficient hysteresis into the system to ensure that BIP-based implementations yield acceptable performance results.
Abstract: In determining the electromagnetic properties of
magnetic materials, hysteresis modeling is of high importance. Many
models are available to investigate those characteristics but they tend
to be complex and difficult to implement. In this paper a new
qualitative hysteresis model for ferromagnetic core is presented,
based on the function approximation capabilities of adaptive neuro
fuzzy inference system (ANFIS). The proposed ANFIS model
combined the neural network adaptive capabilities and the fuzzy
logic qualitative approach can restored the hysteresis curve with a
little RMS error. The model accuracy is good and can be easily
adapted to the requirements of the application by extending or
reducing the network training set and thus the required amount of
measurement data.
Abstract: A new power regulator controller with multiple-access
PID compensator is proposed, which can achieve a minimum memory
requirement for fully table look-up. The proposed regulator controller
employs hysteresis comparators, an error process unit (EPU) for
voltage regulation, a multiple-access PID compensator and a lowpower-
consumption digital PWM (DPWM). Based on the multipleaccess
mechanism, the proposed controller can alleviate the penalty of
large amount of memory employed for fully table look-up based PID
compensator in the applications of power regulation. The proposed
controller has been validated with simulation results.
Abstract: The Proton Exchange Membrane Fuel Cell (PEMFC)
control system has an important effect on operation of cell.
Traditional controllers couldn-t lead to acceptable responses because
of time- change, long- hysteresis, uncertainty, strong- coupling and
nonlinear characteristics of PEMFCs, so an intelligent or adaptive
controller is needed. In this paper a neural network predictive
controller have been designed to control the voltage of at the
presence of fluctuations of temperature. The results of
implementation of this designed NN Predictive controller on a
dynamic electrochemical model of a small size 5 KW, PEM fuel cell
have been simulated by MATLAB/SIMULINK.
Abstract: A comprehensive program of laboratory testing on a
compacted kaolin in a modified triaxial cell was perform to
investigate the influence of hydraulic hysteresis on effective stress in
unsaturated soils. The test data are presented on a range of constant
suction shear tests along wetting and drying paths. The values of
effective stress parameter χ at different matric suction were
determined using the test results. The effect of hydraulic hysteresis
phenomenon on the effective stress was observed. The values of
effective stress parameter χ obtained from the experiments were
compared with those obtained from the expressions proposed in
literature.
Abstract: This paper aims to give a full study of the dynamic
behavior of a mono-phase active power filter. First, the principle of
the parallel active power filter will be introduced. Then, a
dimensioning procedure for all its components will be explained in
detail, such as the input filter, the current and voltage controllers.
This active power filter is simulated using OrCAD program showing
the validity of the theoretical study.
Abstract: In this paper a new maximum power point tracking
algorithm for photovoltaic arrays is proposed. The algorithm detects
the maximum power point of the PV. The computed maximum
power is used as a reference value (set point) of the control system.
ON/OFF power controller with hysteresis band is used to control the
operation of a Buck chopper such that the PV module always
operates at its maximum power computed from the MPPT algorithm.
The major difference between the proposed algorithm and other
techniques is that the proposed algorithm is used to control directly
the power drawn from the PV.
The proposed MPPT has several advantages: simplicity, high
convergence speed, and independent on PV array characteristics. The
algorithm is tested under various operating conditions. The obtained
results have proven that the MPP is tracked even under sudden
change of irradiation level.
Abstract: Efficient handoff algorithms are a cost-effective way
of enhancing the capacity and QoS of cellular system. The higher
value of hysteresis effectively prevents unnecessary handoffs but
causes undesired cell dragging. This undesired cell dragging causes
interference or could lead to dropped calls in microcellular
environment. The problems are further exacerbated by the corner
effect phenomenon which causes the signal level to drop by 20-30 dB
in 10-20 meters. Thus, in order to maintain reliable communication
in a microcellular system new and better handoff algorithms must be
developed. A fuzzy based handoff algorithm is proposed in this paper
as a solution to this problem. Handoff on the basis of ratio of slopes
of normal signal loss to the actual signal loss is presented. The fuzzy
based solution is supported by comparing its results with the results
obtained in analytical solution.
Abstract: This paper presents a comparative study on two most
popular control strategies for Permanent Magnet Synchronous Motor
(PMSM) drives: field-oriented control (FOC) and direct torque
control (DTC). The comparison is based on various criteria including
basic control characteristics, dynamic performance, and
implementation complexity. The study is done by simulation using
the Simulink Power System Blockset that allows a complete
representation of the power section (inverter and PMSM) and the
control system. The simulation and evaluation of both control
strategies are performed using actual parameters of Permanent
Magnet Synchronous Motor fed by an IGBT PWM inverter.
Abstract: Most high-performance ac drives utilize a current
controller. The controller switches a voltage source inverter (VSI)
such that the motor current follows a set of reference current
waveforms. Fixed-band hysteresis (FBH) current control has been
widely used for the PWM inverter. We want to apply the same
controller for the PWM AC chopper. The aims of the controller is to
optimize the harmonic content at both input and output sides, while
maintaining acceptable losses in the ac chopper and to control in
wide range the fundamental output voltage. Fixed band controller has
been simulated and analyzed for a single-phase AC chopper and are
easily extended to three-phase systems. Simulation confirmed the
advantages and the excellent performance of the modulation method
applied for the AC chopper.
Abstract: Un-doped GaN film of thickness 1.90 mm, grown on
sapphire substrate were uniformly implanted with 325 keV Mn+ ions
for various fluences varying from 1.75 x 1015 - 2.0 x 1016 ions cm-2 at
3500 C substrate temperature. The structural, morphological and
magnetic properties of Mn ion implanted gallium nitride samples
were studied using XRD, AFM and SQUID techniques. XRD of the
sample implanted with various ion fluences showed the presence of
different magnetic phases of Ga3Mn, Ga0.6Mn0.4 and Mn4N.
However, the compositions of these phases were found to be
depended on the ion fluence. AFM images of non-implanted sample
showed micrograph with rms surface roughness 2.17 nm. Whereas
samples implanted with the various fluences showed the presence of
nano clusters on the surface of GaN. The shape, size and density of
the clusters were found to vary with respect to ion fluence. Magnetic
moment versus applied field curves of the samples implanted with
various fluences exhibit the hysteresis loops. The Curie temperature
estimated from zero field cooled and field cooled curves for the
samples implanted with the fluence of 1.75 x 1015, 1.5 x 1016 and 2.0
x 1016 ions cm-2 was found to be 309 K, 342 K and 350 K
respectively.
Abstract: We present a new method for the fully automatic 3D
reconstruction of the coronary artery centerlines, using two X-ray
angiogram projection images from a single rotating monoplane
acquisition system. During the first stage, the input images are
smoothed using curve evolution techniques. Next, a simple yet
efficient multiscale method, based on the information of the Hessian
matrix, for the enhancement of the vascular structure is introduced.
Hysteresis thresholding using different image quantiles, is used to
threshold the arteries. This stage is followed by a thinning procedure
to extract the centerlines. The resulting skeleton image is then pruned
using morphological and pattern recognition techniques to remove
non-vessel like structures. Finally, edge-based stereo correspondence
is solved using a parallel evolutionary optimization method based on
f symbiosis. The detected 2D centerlines combined with disparity
map information allow the reconstruction of the 3D vessel
centerlines. The proposed method has been evaluated on patient data
sets for evaluation purposes.
Abstract: This paper proposes a synchronized random switching frequency pulse width modulation (SRSFPWM). In this technique, the clock signal is used to control the random noise frequency which is produced by the feedback voltage of a hysteresis circuit. These make the triangular carrier frequency equaling to the random noise frequency in each switching period with the symmetrical positive and negative slopes of triangular carrier. Therefore, there is no error voltage in PWM signal. The PSpice simulated results shown the proposed technique improved the performance in case of low frequency harmonics of PWM signal comparing with conventional random switching frequency PWM.
Abstract: This paper describes dynamic analysis using proposed
fast finite element method for a shock absorbing structure including a
sponge. The structure is supported by nonlinear concentrated springs.
The restoring force of the spring has cubic nonlinearity and linear
hysteresis damping. To calculate damping properties for the structures
including elastic body and porous body, displacement vectors as
common unknown variable are solved under coupled condition. Under
small amplitude, we apply asymptotic method to complex eigenvalue
problem of this system to obtain modal parameters. And then
expressions of modal loss factor are derived approximately. This
approach was proposed by one of the authors previously. We call this
method as Modal Strain and Kinetic Energy Method (MSKE method).
Further, using the modal loss factors, the discretized equations in
physical coordinate are transformed into the nonlinear ordinary
coupled equations using normal coordinate corresponding to linear
natural modes. This transformation yields computation efficiency. As
a numerical example of a shock absorbing structures, we adopt double
skins with a sponge. The double skins are supported by nonlinear
concentrated springs. We clarify influences of amplitude of the input
force on nonlinear and chaotic responses.
Abstract: The current practice of determination of moisture diffusivity of building materials under laboratory conditions is predominantly aimed at the absorption phase. The main reason is the simplicity of the inverse analysis of measured moisture profiles. However, the liquid moisture transport may exhibit significant hysteresis. Thus, the moisture diffusivity should be different in the absorption (wetting) and desorption (drying) phase. In order to bring computer simulations of hygrothermal performance of building materials closer to the reality, it is then necessary to find new methods for inverse analysis which could be used in the desorption phase as well. In this paper we present genetic algorithm as a possible method of solution of the inverse problem of moisture transport in desorption phase. Its application is demonstrated for AAC as a typical building material.
Abstract: This paper describes vibration analysis using the finite
element method for a small earphone, especially for the diaphragm
shape with a low-rigidity. The viscoelastic diaphragm is supported by
multiple nonlinear concentrated springs with linear hysteresis
damping. The restoring forces of the nonlinear springs have cubic
nonlinearity. The finite elements for the nonlinear springs with
hysteresis are expressed and are connected to the diaphragm that is
modeled by linear solid finite elements in consideration of a complex
modulus of elasticity. Further, the discretized equations in physical
coordinates are transformed into the nonlinear ordinary coupled
equations using normal coordinates corresponding to the linear natural
modes. We computed the nonlinear stationary and non-stationary
responses due to the internal resonance between modes with large
amplitude in the nonlinear springs and elastic modes in the diaphragm.
The non-stationary motions are confirmed as the chaos due to the
maximum Lyapunov exponents with a positive number. From the time
histories of the deformation distribution in the chaotic vibration, we
identified nonlinear modal couplings.
Abstract: To compute dynamic characteristics of nonlinear viscoelastic springs with elastic structures having huge degree-of-freedom, Yamaguchi proposed a new fast numerical method using finite element method [1]-[2]. In this method, restoring forces of the springs are expressed using power series of their elongation. In the expression, nonlinear hysteresis damping is introduced. In this expression, nonlinear complex spring constants are introduced. Finite element for the nonlinear spring having complex coefficients is expressed and is connected to the elastic structures modeled by linear solid finite element. Further, to save computational time, the discrete equations in physical coordinate are transformed into the nonlinear ordinary coupled equations using normal coordinate corresponding to linear natural modes. In this report, the proposed method is applied to simulation for impact responses of a viscoelastic shock absorber with an elastic structure (an S-shaped structure) by colliding with a concentrated mass. The concentrated mass has initial velocities and collides with the shock absorber. Accelerations of the elastic structure and the concentrated mass are measured using Levitation Mass Method proposed by Fujii [3]. The calculated accelerations from the proposed FEM, corresponds to the experimental ones. Moreover, using this method, we also investigate dynamic errors of the S-shaped force transducer due to elastic mode in the S-shaped structure.
Abstract: A macroscopic constitutive equation is developed for a high-density cellulose insulation material with emphasis on the outof- plane stress relaxation behavior. A hypothesis is proposed where the total stress is additively composed by an out-of-plane visco-elastic isotropic contribution and an in-plane elastic orthotropic response. The theory is validated against out-of-plane stress relaxation, compressive experiments and in-plane tensile hysteresis, respectively. For large scale finite element simulations, the presented model provides a balance between simplicity and capturing the materials constitutive behaviour.