Normalized Pulse Width Research Articles

Efficient control techniques to enhance STATCOM performance with DE algorithm

This paper describes the performances of STATCOM by adopting various control techniques. In recent time, variety of control techniques are adopted in Power transmission systems. In this paper focused with reactive power control in STATCOM. In this paper both fundamental concepts associated with the reactive power control & its various techniques are studied. Normally harmonics are higher in normal Pulse Width Modulation (PWM) methods; So Space Vector Pulse Width Modulation (SVPWM) is adopted to reduce harmonics. The proposed system enhance the STATCOM performances in reduced harmonics, avoid voltage sag and swell, regulate the linear power flow and maintains healthy transmission and distribution line parameters. Apart from SPWM and SVPWM, Differently Evolution (DE) is used here to reduce harmonics and other parameters in order to enhance the performance and operation of STATCOM.

Photoplethysmography signal analysis to assess obesity, age group and hypertension.

Photoplethysmography (PPG) provides a simple, convenient and noninvasive method to assess pulse oximetry. Several attempts have been made to use PPG also to estimate blood pressure and arterial stiffness. This paper attempts to assess obesity classes, age group, and hypertension classes using PPG measured from the finger. One set of features was derived from the normalized pulse width of PPG and the other from original PPG. The features were calculated based on the pulse decomposition analysis using five lognormal functions and the up-slope of the PPG pulse. Using kNN and SVM as classifiers, the results were validated using leave-one-out validation. Performances of both features sets have no significant difference, and the kNN outperformed the SVM. The best accuracies are 93%, 88%, and 92% for obesity (5 classes), age group (7 classes), and hypertension (4 classes) respectively. These three assessment targets have a strong relationship with arterial stiffness, therefore it also leads to a study about arterial stiffness using PPG. Width normalization to 1 second might affect some features points based on pulse decomposition analysis. This study also found that the up-slope analysis might give good indices when width normalization was employed. However, these findings still require more experiments to gain conclusions that are more comprehensive.

Spatiotemporal rapidly autofocused ring Pearcey Gaussian vortex wavepackets

We introduce a class of rapidly autofocused ring Pearcey Gaussian vortex (RPGV) beams based on the Pearcey function of catastrophe theory. The distribution of beams can be adjusted by changing the spatial distribution factor pS and topological charge m. In particular, by reducing the parameter pS, the beams can autofocus more quickly, and the peak intensity of beams at the focal point can be increased by dozens of times than that at the initial plane. Further, combining temporal Pearcey Gaussian pulses with spatial RPGV beams, spatiotemporal rapidly autofocused RPGV wavepackets are obtained, and the pulse focal point can always reach the spatial focus by setting well the normalized pulse width wT, which makes the light intensity of the spatial focal point further improve.

Optimization of GaAs semiconductor saturable absorber Q-switched lasers

The expressions of pulse characteristics such as output energy, peak power, and pulse width are obtained by solving the coupled rate equations describing the operation of GaAs semiconductor saturable absorber Q-switched lasers. The key parameters of an optimally coupled GaAs saturable absorber Q-switched laser are determined and several design curves are generated from these expressions for the first time. These key parameters include the optimal normalized coupling parameters and the optimal normalized saturable absorber parameters that maximize the output energy or maximize the peak power, and the corresponding normalized energy, normalized peak power, and normalized pulse width. Using the expressions and design curves, one can predict the pulse characteristics and perform the design of an optimally coupled GaAs saturable absorber Q-switched laser.

Optimization of doubly Q-switched lasers with both an acousto-optic modulator and a GaAs saturable absorber

A doubly Q-switched laser with both an acousto-optic (AO) modulator and a GaAs saturable absorber can obtain a more symmetric and shorter pulse with high pulse peak power, which has been experimentally proved. The key parameters of an optimally coupled doubly Q-switched laser with both an AO modulator and a GaAs saturable absorber are determined, and a group of general curves are generated for what we believe is the first time, when the single-photon absorption (SPA) and two-photon absorption (TPA) processes of GaAs are combined, and the Gaussian spatial distributions of the intracavity photon density and the initial population-inversion density as well as the influence of the AO Q-switch are considered. These key parameters include the optimal normalized coupling parameter, the optimal normalized GaAs saturable absorber parameters, and the normalized parameters of the AO Q-switch, which can maximize the output energy. Meanwhile, the corresponding normalized energy, the normalized peak power, and the normalized pulse width are given. The curves clearly show the dependence of the optimal key parameters on the parameters of the gain medium, the GaAs saturable absorber, the AO Q-switch, and the resonator. Sample calculations for a diode-pumped Nd3+:YVO4 laser with both an AO modulator and a GaAs saturable absorber are presented to demonstrate the use of the curves and the relevant formulas.

Optimization of peak power of doubly Q-switched lasers with both an acousto-optic modulator and a Cr^4+-doped saturable absorber

A doubly Q-switched laser can obtain a shorter pulse with a stable repetition rate and high pulse peak power, which has been experimentally proved. By taking into account the Gaussian spatial distributions of the intracavity photon density and the initial population-inversion density as well as the influence of the acousto-optic (AO) Q switch, we introduce the coupled rate equations for a doubly Q-switched laser with both an AO modulator and a Cr(4+)-doped saturable absorber. These coupled rate equations are solved numerically. The key parameters of an optimally coupled doubly Q-switched laser are determined based on maximizing the peak power, which include the optimal normalized coupling parameter, the optimal normalized saturable absorber parameters, and the normalized parameters of the AO Q switch. The optimal normalized peak power, the corresponding normalized energy, and the normalized pulse width are also given, and a group of general curves are generated for the first time to our knowledge. The curves can give us a good understanding of the dependence of the optimal key parameters on the parameters of the gain medium, the saturable absorber, the AO Q switch, the resonator, and the spatial distributions of the intracavity photon density. The optimal calculations for a diode-pumped Nd(3+):YVO(4) laser with both an AO modulator and a Cr(4+):YAG saturable absorber are presented to demonstrate the use of the curves and the related formulas.

Optimization of the slowly actively Q-switched laser

By taking into account turnoff time of the slowly active Q-switch, the coupled equations of a slowly actively Q-switched laser are given. These rate equations are solved numerically. The key parameters of an optimally coupled actively Q-switched laser with the turnoff time are determined, and a group of general curves are generated for the first time. These key parameters include the optimal normalized coupling parameter which maximizes the output energy, and the corresponding normalized energy, normalized peak power and normalized pulse width. The curves clearly show the dependence of the optimal key parameters on the parameters of the gain medium and the resonator. In addition, the importance of including turnoff time of the slowly active Q-switch is also shown. The optimal calculations for an actively Q-switched Nd:YVO 4 laser with acoustic–optic modulator are presented to demonstrate the use of the curves and the related formulas.

Optimization of Passively Q-switched Lasers by Taking into Account Intracavity Laser Spatial Distribution

The intracavity photon density and the initial population-inversion density in the diode-pumped passively Q-switched lasers are assumed to be Gaussian spatial distributions. The space-dependent rate equations are solved numerically. The key parameters of an optimally coupled passively Q-switched laser under Gaussian approximation are determined, and a group of general curves are generated for the first time. These key parameters include the optimal normalized coupling parameter and the optimal normalized saturable absorber parameter that maximize the output energy, and the corresponding normalized energy, normalized peak power, and normalized pulse width. The curves clearly show the dependence of the optimal key parameters on the parameters of the gain medium, the saturable absorber, and the resonator. In addition, the importance including the space variation is also shown. The optimal calculations for a diode-pumped passively Nd: YVO4 laser are presented to demonstrate the use of the curves and the related formulas.

Optimization of peak power of passively Q-switched lasers by taking into account intracavity laser spatial distribution

The intracavity photon density and the initial population-inversion density in the diode-pumped passively Q-switched lasers are assumed to be Gaussian spatial distributions. The space-dependent rate equations are solved numerically. The key parameters of an optimally coupled passively Q-switched laser under Gaussian approximation are determined, and a group of general curves are generated for the first time. These key parameters include the optimal normalized coupling parameter and the optimal normalized saturable absorber parameter that maximize the peak power, and the corresponding normalized energy, normalized peak power, and normalized pulse width. The curves clearly show the dependence of the optimal key parameters on the parameters of the gain medium, the saturable absorber, and the resonator. In addition, the importance including the space variation is also shown. The optimal calculations for a diode-pumped passively Nd : YVO 4 laser are presented to demonstrate the use of the curves and the related formulas.

Sensor saturation effects on NLTS measurements [of magnetoresistive sensors

The effects of sensor saturation on measurements of nonlinear transition shift (NLTS) are compared for the harmonic elimination and extracted dibit methods. The error in the fifth harmonic method is sensitive to the normalized pulse width and to the amount of saturation; the NLTS measured by this technique underestimates the actual NLTS value, and the reduction can be more than 30% for reasonable values of PW/sub 50//T and sensor saturation. The NLTS calculated from the /spl epsiv//sub 1/ echo in the extracted dibit method is relatively insensitive to the amount of saturation, with errors typically less than 5%.

A simplified dispersion limit formula for IM/DD systems and its comparison with experimental results

A simplified formula for the dispersion limit of single-mode-fiber intensity modulation/direct detection (IM/DD) systems is derived for arbitrary given normalized pulse width U, eye opening penalty X and source linewidth enhancement factor /spl alpha/. From the comparison with published theoretical analyses, computer simulation and experimental data, its validity and the limits of existing formulae are shown. Using this simple and general formula, one can easily obtain the dispersion limit of various fiber types under different working conditions in IM/DD systems.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An acousto-ultrasonic study of the effect of porosity on a sintered glass system

An assessment of the applicability of an acousto-ultrasonic (AU) technique for the monitoring of porous ceramic systems has been carried out. Sintered glass was used as a model system and it was found that the AU parameters, such as normalized ringdown count, normalized pulse width, velocity and frequency interval (Δf) between adjacent peaks in the frequency spectra, decrease with increasing porosity. The porosity dependence of the normalized AU parameters has been attributed to attenuation which analysis showed depended on the pore size and content. The velocity and frequency interval changes also depended on pore content but, unlike the normalized parameters, were found to be sensitive to pore shape and size. The decreasing Δf with increasing porosity was explained in terms of the longer path lengths traversed by the waves in the higher pore-density samples.

A Pulse to Pulse Klystron Diagnosis System

This report describes a system used to study the behavior of SLAC high powered klystrons operating with a twice normal pulse width of 5 ..mu..s. At present, up to eight of the klystrons installed along the accelerator can be operated with long pulses and monitored by this system. The report will also discuss some of the recent findings and investigations.