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Robust Direct Adaptive Controller Design for Photovoltaic Maximum Power Point Tracking Application
摘要： Tracking the maximum output power of a photovoltaic (PV) cell is an important problem to harvest more energy at di?erent weather and load conditions. This paper presents the design and simulation of a robust direct adaptive controller (RDAC) for maximum power point tracking (MPPT) device based on boost converter topology. A mathematical model is developed, and a suitable RDAC is designed for MPPT device, and simulations are performed using MATLAB/Simulink to verify the controller’s robustness at varying operating conditions. The real-time irradiance and temperature data are used on an hourly basis to test the suggested MPPT adaptive controller for a typical sunny day in summer and winter. The simulation results show that the RDAC performs excellent tracking under varying conditions such as irradiance, temperature, load, boost converter inductance, and capacitance.
关键词： adaptive control,boost converter,MPPT,photovoltaic,simulink,compensator design
更新于2025-09-11 14:15:04
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Borosilicate Based Hollow-Core Optical Fibers
摘要： We discuss the fabrication of hollow-core optical ?bers made of borosilicate glass. We show that, despite the high attenuation of the glass relative to silica, the ?ber optical losses can be of the same order of magnitude of those obtained by using ultrapure silica glass. Short lengths of the fabricated ?bers, used in combination with incoherent optical sources, provide single-mode optical guidance in both near and mid-infrared spectral ranges without any additional optical components.
关键词： ?ber design and fabrication,?ber properties,microstructured ?bers
更新于2025-09-11 14:15:04
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Experimental Investigation of Laser Surface Transformation Hardening of 4340 Steel Spur Gears
摘要： This paper presents an experimental investigation of laser surface transformation hardening (LSTH) of 4340 steel spur gears using regression analysis. The experimental work is focused on the effects of various LSTH parameters on the hardness profile shape and the hardened depth variation. The investigations are based on a structured design of experiments and improved statistical analysis tools. The experimentations are carried out on AISI 4340 steel spur gears using a commercial 3 kW Nd:YAG laser system. Laser power, scanning speed, and rotation speed are used as process parameters to evaluate the variation of the hardened depth and to identify the possible relationship between the process parameters and the hardened zone physical and geometrical characteristics. Based on the experimental data and analysis of variance, the direct and interactive contributions of the process parameters on the variation of the hardness profile shape and the hardened depth are analyzed. The main effects and the interaction effects are also evaluated. The results reveal that all the process parameters are relevant. The cumulative contribution of the three parameters in the hardened depth variation represents more than 80% with a clear predominance of laser power. The contribution of the interactions between the parameters represents 12% to 16%. The resulting hardness values are relatively similar for all the experimental tests with about 60 HRC. The evaluation of the produced regression models for hardened depth prediction shows limited performance suggesting that the predictive modeling process can be improved.
关键词： design of experiments,analysis of variance,hardness profile,hardened depth,laser surface transformation hardening,AISI 4340 alloy steel,spur gears
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Short-Wavelength, Near-Diffraction-Limited Beam, 792 nm Cladding Pumped Efficient Thulium-Doped Fiber Laser in a Power-Scalable Fiber Design
摘要： Thulium-doped fiber lasers (TDFLs) offer a broad 3F4 → 3H6 emission band ~1600-2200 nm. Thanks to “two-for-one” cross-relaxation process in TDFLs, that enables to achieve output power > 1 kW at ~2045 nm with 0.79-μm cladding-pumping. Efficient cross-relaxation requires high Tm-concentration ( > 3wt%). This results in a high core refractive index (thus higher V-number) that degrades the beam quality. It also increases the thermal load per unit length, although this can be reduced by a large cladding-to-core area ratio that increases the absorption length of the fiber. A long fiber also shifts the emission to long wavelengths with more signal re-absorption. For short-wavelength emission the re-absorption must be reduced in some other way, which also ensures adequate total pump absorption. Simplest technique is to reduce the area ratio, but then excessive thermal load or inefficient cross-relaxation (if the Tm-concentration is low to reduce the thermal load per unit length) hampers power-scaling.
关键词： short-wavelength,Thulium-doped fiber lasers,power-scalable fiber design,near-diffraction-limited beam
更新于2025-09-11 14:15:04
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A planar eight‐way compact substrate integrated waveguide based radial power divider with broadband performance
摘要： A compact broadband eight-way substrate integrated waveguide (SIW) based radial power divider at C-band is presented in the article. Bandwidth enhancement is achieved by employing planar impedance transformer consisting of an annular slot and circular patch at the input and output feed positions. The equivalent circuit analysis helps in the optimization of the annular slot and circular patch on the substrate. The proposed compact power divider has fractional bandwidth of 53.5% for 15 dB input return loss. Broadband characteristics are achieved without using any bulky mechanical arrangement for feed matching. It has a size of 0.72 λg 2 and the measured amplitude imbalance is within 0.5 dB at the center frequency of 6.6 GHz.
关键词： substrate integrated waveguide,compact design,power divider,broadband,eight-way
更新于2025-09-11 14:15:04
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Optimization of LED Lighting for Clinical Settings
摘要： The advent of the LED light source has promoted the concept of human-centric lighting (HCL). The LED has also been responsible for increases in the electrical e?ciency of lighting systems, coupled with recent improvements in their colour properties. We have found that it is also possible to create a lit environment with enhanced clinical attributes by providing a source spectrum that meets the requirements of the Cyanosis Observation Index (COI). This paper describes the use of a di?erential evolution (DE) algorithm for the spectral design of a mixed LED light source capable of meeting COI recommendations as well as HCL performance criteria.
关键词： differential evolution algorithm,Cyanosis Observation Index,LED lighting,human-centric lighting,spectral design
更新于2025-09-11 14:15:04
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The operation of THz quantum cascade laser in the region of negative differential resistance
摘要： We investigate the light-current-voltage characteristics and emission spectra of 2.3 THz quantum cascade laser operating in the negative differential resistance (NDR) region. It was shown that the formation of electric ?eld domains (EFDs) leads to a large number of discontinuities on the current-voltage and the total optical power on current characteristics. Measurements of emission spectra at different current (before the NDR region and in the NDR region) shows that the formation of EFDs results in decrease of the output intensity, but does not in?uence on lasing frequencies. The performed calculations qualitatively explain the experimental results.
关键词： THz region,Resonant-phonon design,Quantum-cascade laser,Negative differential resistivity
更新于2025-09-11 14:15:04
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Laser Treatment as Sintering Process for Dispenser Printed Bismuth Telluride Based Paste
摘要： Laser sintering as a thermal post treatment method for dispenser printed p- and n-type bismuth telluride based thermoelectric paste materials was investigated. A high-power fiber laser (600 W, 1064 nm) was used in combination with a scanning system to achieve high processing speed. A Design of Experiment (DoE) approach was used to identify the most relevant processing parameters. Printed layers were laser treated with different process parameters and the achieved sheet resistance, electrical conductivity, and Seebeck coefficient are compared to tube furnace processed reference specimen. For p-type material, electrical conductivity of 22 S/cm was achieved, compared to 15 S/cm in tube furnace process. For n-type material, conductivity achieved by laser process was much lower (7 S/cm) compared to 88 S/cm in furnace process. Also, Seebeck coefficient decreases during laser processing (40–70 μV/K and ?110 μV/K) compared to the oven process (251 μV/K and ?142 μV/K) for p- and n-type material. DoE did not yet deliver a set of optimum processing parameters, but supports doubts about the applicability of area specific laser energy density as a single parameter to optimize laser sintering process.
关键词： additive manufacturing,design of experiment,laser sintering,thermoelectric,antimony telluride,bismuth telluride
更新于2025-09-11 14:15:04
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Optimization of Pulsed Nd:YVO4 Through Transmission Laser Welding of Transparent Acrylic and Polycarbonate
摘要： In the present work through transmission laser welding (TTLW) of two transparent plastic materials namely, Acrylic and Polycarbonate at varied levels of laser power, scanning speed and frequency have been carried out to form lap joints without application of filler material. The effect of input parameters on the weld quality has been studied through inspection and tests. Statistical software Design Expert 10 has been applied for design of experiments and analysis purpose. Breaking load and weld width have been considered as responses. Response surface methodology (RSM) has been applied for multi-objective optimization for minimization of weld width and maximization of breaking load simultaneously. Confirmatory tests have been conducted to validate the applied optimization techniques.
关键词： Design Expert 10,Multi-objective optimization,RSM,TTLW,Acrylic and Polycarbonate
更新于2025-09-11 14:15:04
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A theory of waveguide design for plasmonic nanolasers
摘要： We propose a theory for the waveguide design and analysis for plasmonic nanolasers by reformulating the fundamental waveguide requirements. This theory does not rely on further optimizing previously used structures, but examines each possible design without prejudice. Our exploration of one-dimensional (i.e., layered) plasmonic nanowaveguide geometries and the subsequent extension to 2D structures not only provides a deep understanding of the characteristics of currently used designs, but also leads to superior structures with the potential to address long-standing challenges in plasmonic nanolasers. In addition, we discover analogies between the reformulated fundamental requirements for the waveguide for nanolasers and nanoscale four-wave mixing (FWM) devices. Therefore, after a slight modification, our theory can also be applied to the waveguide design for plasmonic FWM devices.
关键词： four-wave mixing,waveguide design,nanophotonics,plasmonic nanolasers
更新于2025-09-11 14:15:04