High-efficiency microsecond pulse-width laser-converter based on dye solutions

1987 ◽  
Vol 47 (5) ◽  
pp. 1104-1106
Author(s):  
N. M. Artem'ev ◽  
S. A. Batishche ◽  
A. V. Bortkevich ◽  
A. S. Eremenko ◽  
B. G. Maglinin ◽  
...  
Keyword(s):  
Pulse Width ◽  
High Efficiency ◽  
Laser Converter ◽  
Microsecond Pulse ◽  
Dye Solutions

scholarly journals Effect of NS-DBD Actuator Parameters on the Aerodynamic Performance of a Flap Lifting Device

2019 ◽  
Vol 9 (23) ◽  
pp. 5213 ◽  
Author(s):  
Kun Chen ◽  
Chen-Yao Wei ◽  
Zhi-Wei Shi
Keyword(s):  
Energy Density ◽  
Flow Field ◽  
Drag Reduction ◽  
Pulse Width ◽  
High Efficiency ◽  
Aerodynamic Drag ◽  
Pulse Discharge ◽  
Excitation Frequency ◽  
Aerodynamic Performance ◽  
Discharge Pulse

The flap lift device is an important part of the conventional configuration of aircrafts and has an important impact on the aerodynamic performance. In this paper, a high-efficiency, simple, and energy-saving nanosecond dielectric barrier discharge (DBD) plasma actuator is placed in the vicinity of the flap lift device to improve the aerodynamic performance of the flap by controlling the flow field. The two-dimensional airfoil GAW-1 and its 29% flap were selected as the research objects, and the nanosecond (NS) DBD actuators were fixed at different locations near the deflection angle of the 10°flap. The excitation frequency, pulse width, and energy density parameters of the pulse discharge were adjusted, and then, the effects of parameter changes on aerodynamic characteristics of the airfoil were studied by numerical simulation. The simulation results show that adjusting the excitation frequency on the aerodynamic drag is weak and that the effect on the aerodynamic lift is obvious. The increase of the discharge pulse width will have a more significant effect on the flow field, i.e., a proper increase of the discharge pulse width can achieve better drag reduction, and increase lift after a stall at a high angle of attack. Although the increase of discharge energy density can strengthen the pulse perturbation effect on the flow field, it also contributes to some adverse effects and has no obvious optimization effect on the control efficiency of lift increase and drag reduction.

scholarly journals DC-DC Buck Boost Converter For Renewable and Biomedical Application based Real-Time IoT

2019 ◽  
Vol 8 (4) ◽  
pp. 328-336
Keyword(s):  
Pulse Width ◽  
High Efficiency ◽  
Boost Converter ◽  
Heart Beat ◽  
Current Control ◽  
Buck Converter ◽  
Raspberry Pi ◽  
Control Line ◽  
Light Load ◽  
Control Scheme

DC-DC buck boost converter is a conversion circuit using induced frequency inductors, switching.DC-DC converters dynamics was improved by using self calibrated preemptive current control. As, a result Preemptive concurrent control reduces capacitor size by 10x.DC DC buck converter with pulse width modulation.DC-DC buck converter with two step pulse width modulation was utilized for low power application by using delay, control line. Main motive of DC-DC buck converter with pulse width modulations obtains high linearity, high granularity. Conversion efficiency for Light load current was increased in buck converter by clocked hysteresis scheme. Power supplied to comparator was scaled to load easily. Conventional buck converter was integrated with LED to expand smart bulb. Main power from supply was decoupled by Non linear ramp control scheme preventing LED output flickering. Control scheme effectiveness was improved by small signal model. Three major characteristics of Light emitting diodes are improved lifetime, high efficiency, increased reliability, controllability. High brightness LED by multicell three phases was used for its lower cost. Heart beat was identified by using raspberry pi, system on chip with three stages in it namely Heart beat determination, Impedence, cardiography parameters. Accidents was restricted by this method.Overspeeding vehicles was identified was main goal of using complex proportional assessment method. Converting Rice husk into bio fuels was performed by thermo chemical processes. Rice hulk silica was utilized for fluorescent silica particles synthesis.

scholarly journals All-fiber passively mode-locked femtosecond fiber lasers

2021 ◽  
Author(s):  
Jiaqi Zhou
Keyword(s):  
Fiber Laser ◽  
Pulse Energy ◽  
Pulse Width ◽  
Fiber Lasers ◽  
High Efficiency ◽  
Single Mode ◽  
Scaling Up ◽  
Mode Locking ◽  
Raman Signal ◽  
Loop Mirror

This dissertation presents three all-fiber designs of passively mode-locked lasers in order to achieve high pulse energy, environmentally-stable dissipative soliton (DS) operation in all-normal-dispersion cavities. A numerical model for DS mode-locked fiber lasers based on the nonlinear Schrodinger equation has been used to guide the experimental designs. Firstly, an environmentally-stable and ultra-compact SESAM mode-locked fiber laser is demonstrated. The all-fiber design is realized using a mode-field-adaptor (MFA) to couple light onto the SESAM. A polarization-maintaining fiber loop mirror serves multiple functions as a highly reflective mirror, an output coupler and polarization selector. Self-starting and stable DS mode-locking operation is achieved with 1.7 nJ pulse energy and a 22 ps pulse width. Secondly, an ultra-stable DS mode-locking was demonstrated in a long cavity ring laser with a nonlinear amplified loop mirror (NALM) as a mode-locking device. The output pulses of 32 nJ, 615 fs de-chirped pulse width were obtained with the Raman signal suppressed below -20 dB in a 81 m long cavity. The mode-locking is self-starting and the mode-locked pulse train shows excellent stability. Thirdly, the mode-laser cavity was extended with a piece of large-mode-area (LMA) fiber with a low dispersion to further scaling up the pulse energy to 56.8 nJ. The laser pulses were compressed to 750 fs by a pair of volume gratings. In the processing of scaling-up the pulse energy of the NALM mode-locked fiber laser, some interesting physical phenomena were observed, such as the operation regime transition from noise-like to DS with a sudden reduction of Raman signal and a unique waves-splitting with a stable temporal spacing. The phenomena were studied and explained in this dissertation. In addition to the mode-locked fiber laser, a CW and a Q-switched fiber lasers were also designed with a single-mode- multimode- single-mode (SMS) filter as an effective mean of overcoming nonlinear effects. The transmission spectral property of the SMS was studied which fits well with theoretical calculation. One high efficiency SMS CW fiber lasers and one SMS Q-switched fiber laser were designed which showed the effectiveness of the SMS filter for inhibiting the SRS and significantly reducing SPM.

scholarly journals A Novel Soft-Switching Synchronous Buck Converter for Portable Applications

2008 ◽  
Vol 2008 ◽  
pp. 1-9
Author(s):  
Anup Kumar Panda ◽  
Swapnajit Pattnaik ◽  
K. K. Mohapatra
Keyword(s):  
Pulse Width ◽  
High Efficiency ◽  
Low Voltage ◽  
Buck Converter ◽  
Soft Switching ◽  
Pulse Width Modulated ◽  
Zero Voltage Switching ◽  
Overall Efficiency ◽  
Zero Voltage ◽  
Auxiliary Circuit

This paper proposes a zero-voltage-transition (ZVT) pulse-width-modulated (PWM) synchronous buck converter, which is designed to operate at low voltage and high efficiency typically required for portable systems. A new passive auxiliary circuit that allows the main switch to operate with zero-voltage switching has been incorporated in the conventional PWM synchronous buck converter. The operation principles and a detailed steady-state analysis of the ZVT-PWM synchronous converter implemented with the auxiliary circuit are presented. Besides, the main switch and all of the semiconductor devices operate under soft-switching conditions. Thus, the auxiliary circuit provides a larger overall efficiency. The feasibility of the auxiliary circuit is confirmed by simulation and experimental results.

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