scholarly journals Novel Dual Beam Cascaded Schemes for 346 GHz Harmonic-Enhanced TWTs

Electronics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 195
Author(s):  
Ruifeng Zhang ◽  
Qi Wang ◽  
Difu Deng ◽  
Yao Dong ◽  
Fei Xiao ◽  
...  
Keyword(s):  
High Power ◽  
Peak Power ◽  
Low Cost ◽  
High Harmonic ◽  
Harmonic Signal ◽  
Input Power ◽  
Plasma Diagnostic ◽  
Dual Beam ◽  
Thz Sources ◽  
Simulation Results

The applications of terahertz (THz) devices in communication, imaging, and plasma diagnostic are limited by the lack of high-power, miniature, and low-cost THz sources. To develop high-power THz source, the high-harmonic traveling wave tube (HHTWT) is introduced, which is based on the theory that electron beam modulated by electromagnetic (EM) waves can generate high harmonic signals. The principal analysis and simulation results prove that amplifying high harmonic signal is a promising method to realize high-power THz source. For further improvement of power and bandwidth, two novel dual-beam schemes for high-power 346 GHz TWTs are proposed. The first TWT is comprised of two cascaded slow wave structures (SWSs), among which one SWS can generate a THz signal by importing a millimeter-wave signal and the other one can amplify THz signal of interest. The simulation results show that the output power exceeds 400 mW from 340 GHz to 348 GHz when the input power is 200 mW from 85 GHz to 87 GHz. The peak power of 1100 mW is predicted at 346 GHz. The second TWT is implemented by connecting a pre-amplification section to the input port of the HHTWT. The power of 600 mW is achieved from 338 GHz to 350 GHz. The 3-dB bandwidth is 16.5 GHz. In brief, two novel schemes have advantages in peak power and bandwidth, respectively. These two dual-beam integrated schemes, constituted respectively by two TWTs, also feature rugged structure, reliable performance, and low costs, and can be considered as promising high-power THz sources.

5mm × 5mm Sized Slug on High Power LED Stress and Junction Temperature Analysis

2013 ◽  
Vol 404 ◽  
pp. 460-464
Author(s):  
Zaliman Sauli ◽  
Vithyacharan Retnasamy ◽  
Fairul Afzal Ahmad Fuad ◽  
Phaklen Ehkan ◽  
Rajendaran Vairavan ◽  
...  
Keyword(s):  
High Power ◽  
Light Emitting Diode ◽  
Input Power ◽  
Junction Temperature ◽  
Temperature Analysis ◽  
Single Chip ◽  
Physical Size ◽  
Light Emitting ◽  
Simulation Results ◽  
Incandescent Lamps

Conventional incandescent lamps are being replaced by high power light emitting diode as a lighting source due to it ascendancy in terms of physical size, performance, output and lifetime. Nevertheless, the reliability and efficiency of the LED is dependent on the junction temperature. This study presents the thermal simulation of single chip LED package with 5mm x5mmx 1mm aluminum heat slug. The junction temperature and stress of LED chip were evaluated using Ansys version 11. Input power of 0.1 W and 1 W were applied to the LED. The simulation results showed that at input power of 1W, the maximum junction temperature and stress of the LED chip is 112.91°C and 263.82Mpa respectively.

The Modulation Index Optimization of Microwave Photonic Frequency Conversion Using Double-Sideband Suppressed-Carrier and Balance Detection

2015 ◽  
Vol 713-715 ◽  
pp. 475-478
Author(s):  
Wei Jiang ◽  
Qing Gui Tan ◽  
Dong Liang ◽  
Xiao Jun Li ◽  
Zhong Bo Zhu
Keyword(s):  
Theoretical Analysis ◽  
High Power ◽  
Frequency Conversion ◽  
High Harmonic ◽  
Modulation Index ◽  
Harmonic Suppression ◽  
Microwave Photonic ◽  
Mach Zehnder Modulator ◽  
Simulation Results

In this paper, on basis of DPMZM (Dual-Parallel Mach-Zehnder Modulator), an approach for microwave photonic frequency conversion using DSSC(double-sideband suppressed-carrier) and balance detection is demonstrated. DSSC and balance detection were used to realize high harmonic suppression, and achieve frequency conversion signal with high power and high spectrum purity. In addition, theoretical analysis and simulation results show that the optimal modulation index is m1=2, m2=1.81, and the harmonic suppression is greater than 30dB.

scholarly journals Photovoltaic flyback micro-inverter with power decoupling technique

2019 ◽  
Vol 15 (1) ◽  
pp. 9
Author(s):  
Salam Jabr ◽  
Adel A. Obed
Keyword(s):  
Single Phase ◽  
Low Cost ◽  
Harmonic Distortion ◽  
Input Power ◽  
Power Fluctuation ◽  
Pv System ◽  
Snubber Circuit ◽  
Power Decoupling ◽  
Simulation Results ◽  
Micro Inverter

This paper proposes a low-cost single-phase micro-inverter for grid-connected photovoltaic (PV) system. The lifetime of the conventional flyback micro-inverter is shortened, because lifetime of a large electrolyte capacitor is shortened. For this reason, the need for a large electrolyte capacitor is avoided by proposing power decoupling (PD) circuit. Dual advantages are achieved by proposed circuit, first high-power decoupling with small capacitances and other to protect the main MOSFET from spike voltage stress during turn off time without needing for additional a snubber circuit. Consequently, PD circuit is already used as a snubber circuit to absorb the leakage energy in the transformer which may destroy the switch and thus the voltage spike on the main MOSFET decreased. In addition, operating principle, modes, and control scheme of the proposed micro-inverter are discussed. As the simulation results, the input power ripple of the single-phase power fluctuation is under than 4%, unity power factor (P.F) and the total harmonic distortion (THD) of the proposed inverter output current is less than 5%. PSIM tool box is provided to simulate the proposed system and the simulation results are adequate.

A Commercial Low Cost, Highly Efficient UC3842 based High Brightness LED (HBLED) Lamp

2018 ◽  
Vol 9 (1) ◽  
pp. 1
Author(s):  
Devi Maheswaran ◽  
Sreedevi V T
Keyword(s):  
Low Cost ◽  
Current Mode ◽  
Input Power ◽  
High Brightness ◽  
Light Emitting ◽  
Extensive Simulation ◽  
Fluorescent Lamps ◽  
Led Array ◽  
Simulation Results ◽  
Laboratory Prototype

The conventional lighting sources like incandescent and fluorescent lamps are replaced by High Brightness Light Emitting Diodes (HB-LEDs). In this paper, a HBLED driver using a Single Ended Primary Inductor Converter (SEPIC) with input Power Factor Correction (PFC) is presented.  PFC is accomplished using a commercial inexpensive Peak Current Mode Controller (PCMC) IC UC3842 is newly combined with SEPIC converter. Extensive simulation results are carried out and a laboratory prototype to power 18W LED array from AC mains is implemented and the results are presented in detail.

An Ankle Exoskeleton Using a Lightweight Motor to Create High Power Assistance for Push-Off

2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Jiazhen Liu ◽  
Caihua Xiong ◽  
Chenglong Fu
Keyword(s):  
High Power ◽  
Peak Power ◽  
Stance Phase ◽  
Input Power ◽  
High Mass ◽  
Motor Power ◽  
Power Amplification ◽  
Ankle Exoskeleton ◽  
Four Bar Linkage ◽  
Power Assistance

Abstract Active exoskeletons have capacity to provide biologically equivalent levels of joint mechanical power, but high mass of actuation units may lead to uncoordinated walking and extra metabolic consumption. Active exoskeletons normally supply assistance directly during push-off and have a power burst during push-off. Thus, the requirements on power of motors are high, which is the main reason for the high mass. However, in a muscle-tendon system, the strategy of injecting energy slowly and releasing quickly is utilized to obtain a higher peak power than that of muscle alone. Application of this strategy of peak power amplification in exoskeleton actuation might lead to reductions of input power and device mass. This paper presents an ankle exoskeleton which can accumulate the energy injected by a motor during the swing phase and mostly the stance phase and then release it quickly during push-off. An energy storage and release system was developed using a four-bar linkage clutch. In addition, evaluation experiments on the exoskeleton were carried out. Results show that the exoskeleton could provide a high power assistance with a low power motor and reduced the requirement on motor power by 4.73 times. Besides, when walking with the exoskeleton, the ankle peak power was reduced by 25.8% compared to the normal condition. The strategy which imitates the working pattern of the muscle-tendon system leads to a lightweight and effective exoskeleton actuation, and it also supplies ideas for the designs of lightweight actuators that work discontinuously in other conditions.

Study and design of dual stator permanent magnet machine with spoke-type configurations using phase-group concentrated-coil windings

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1381-1389
Author(s):  
Dezhi Chen ◽  
Chengwu Diao ◽  
Zhiyu Feng ◽  
Shichong Zhang ◽  
Wenliang Zhao
Keyword(s):  
Permanent Magnet ◽  
Permanent Magnets ◽  
Low Cost ◽  
Dynamic Performance ◽  
Torque Ripple ◽  
Permanent Magnet Machine ◽  
Torque Density ◽  
Phase Group ◽  
High Torque ◽  
Simulation Results

In this paper, a novel dual-stator permanent magnet machine (DsPmSynM) with low cost and high torque density is designed. The winding part of the DsPmSynM adopts phase-group concentrated-coil windings, and the permanent magnets are arranged by spoke-type. Firstly, the winding structure reduces the amount of copper at the end of the winding. Secondly, the electromagnetic torque ripple of DsPmSynM is suppressed by reducing the cogging torque. Furthermore, the dynamic performance of DsPmSynM is studied. Finally, the experimental results are compared with the simulation results.

To Eliminate Curtain Effect of FIB TEM Samples by a Combination of Sample Dicing and Backside Milling

2014 ◽  
Author(s):  
Jian-Shing Luo ◽  
Hsiu Ting Lee
Keyword(s):  
Sample Preparation ◽  
Focused Ion Beam ◽  
Preparation Method ◽  
Low Cost ◽  
Ion Beam ◽  
Sample Preparation Method ◽  
Site Specific ◽  
Dual Beam ◽  
Transmission Electron

Abstract Several methods are used to invert samples 180 deg in a dual beam focused ion beam (FIB) system for backside milling by a specific in-situ lift out system or stages. However, most of those methods occupied too much time on FIB systems or requires a specific in-situ lift out system. This paper provides a novel transmission electron microscopy (TEM) sample preparation method to eliminate the curtain effect completely by a combination of backside milling and sample dicing with low cost and less FIB time. The procedures of the TEM pre-thinned sample preparation method using a combination of sample dicing and backside milling are described step by step. From the analysis results, the method has applied successfully to eliminate the curtain effect of dual beam FIB TEM samples for both random and site specific addresses.

Design Technique of High Power Efficiency LLC DC-DC Converters for Photovoltaic Cells

2018 ◽  
Vol 2 (1) ◽  
pp. 30
Author(s):  
Hisatsugu Kato ◽  
Yoichi Ishizuka ◽  
Kohei Ueda ◽  
Shotaro Karasuyama ◽  
Atsushi Ogasahara
Keyword(s):  
High Power ◽  
Power Efficiency ◽  
Photovoltaic Cells ◽  
Input Voltage ◽  
Design Technique ◽  
Load Range ◽  
Voltage Range ◽  
Simulation Results ◽  
Secondary Side ◽  
High Power Efficiency

This paper proposes a design technique of high power efficiency LLC DC-DC Converters for Photovoltaic Cells. The secondary side circuit and transformer fabrication of proposed circuit are optimized for overcoming the disadvantage of limited input voltage range and, realizing high power efficiency over a wide load range of LLC DC-DC converters. The optimized technique is described with theoretically and with simulation results. Some experimental results have been obtained with the prototype circuit designed for the 80 - 400 V input voltage range. The maximum power efficiency is 98 %.

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