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- 实验方案
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Diffusion charge compensation strategy for power balancing in capacitor-less photovoltaic modules during partial shading
摘要： Photovoltaic arrays are highly susceptible to the partial shading that drastically reduces the power output by forming multiple peaks in the characteristics curves complicating the operation of maximum power point trackers (MPPTs). In this paper, a new diffusion charge compensation strategy for power enhancement in the arrays during partial shading has been proposed. The strategy eliminates the requirement of bypass diodes and passive energy storage components and uses the inherent diffusion capacitance of the module for power balancing during shading reducing cost and complexity. The strategy has been tested in MATLAB/Simulink environment and validated experimentally under various partial shading scenarios. The proposed strategy increases the power output and improves the tracking efficiency of the MPPTs by forming single maxima in the characteristics curves of the array during partial shading as compared to the conventional arrays with and without bypass diodes. Also, the proposed strategy excels in performance by increasing the power output of arrays during partial shading with a conversion efficiency of nearly 98%.
关键词： Photovoltaic,Power generation,Partial shading,Diffusion capacitance,Maximum power point tracker,Charge compensation
更新于2025-09-12 10:27:22
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High Power Quantum Cascade Laser at λ 5.1 <i>μ</i> m Based on Low Strain Compensation Design
摘要： We demonstrate the development of a high performance quantum cascade laser at (cid:2) ～ 5(cid:3)1 (cid:4)m with low strain-balanced structure using a double-phonon resonant design approach. The wafer was grown by solid source molecular beam epitaxy and fabricated with buried heterostructure waveguides. A high output power up to 1.5 W is obtained at 288 K with a high wall plug ef?ciency of 8.5% for devices with stripe dimension of 5 mm × 10 (cid:4)m. The characteristic temperatures, T 1, are 114 K and 198 K respectively.
关键词： High Power Laser,Strain-Compensation,Quantum Cascade Laser
更新于2025-09-12 10:27:22
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Evaluation and compensation of laser-based on-machine measurement for inclined and curved profiles
摘要： On-machine measurement is being applied increasingly commonly to inspect deviations in machining, without removing the workpiece from the machine. A laser-based non-contact method has been introduced to measure complex profiles highly efficiently, but the accuracy of its measurement has not been assessed and compensated for. To improve the accuracy of the measurements of inclined and curved profiles using a laser displacement sensor, this study evaluates and compensates for deviations in the measured values by using compensation strategies. The factors influencing measurement accuracy are analyzed and the phenomenon of secondary reflection is explained on the basis of laser triangulation. For an inclined profile, the strategy whereby angle compensation is carried out followed by displacement compensation is used. For a curved profile, a corrected formula in which the coefficients are calculated according to the measurements is applied. The two patterns of coarse and fine compensation rely on the choice of the correction coefficient determined by the adaptive requirements of assessing accuracy. The results show that the surface roughness, measuring environment, and positional errors are less important than the inclination angle and displacement in affecting the accuracy. For the inclined profile, the measurement accuracy improved to －7.4 μm～＋6.7 μm after compensation. For the curved profile, the deviations decreased by 71.5% and 91.9% compared with the original after coarse and fine compensations, respectively. Furthermore, the compensation strategies can be applied to the measurement of complex profiles in future work.
关键词： Compensation strategy,Secondary reflection,Complex profiles,Laser-based on-machine measurement
更新于2025-09-12 10:27:22
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High-sensitivity hydraulic pressure sensor based on Fabry-Perot interferometer filled with polydimethylsiloxane film
摘要： A high-sensitivity hydraulic pressure sensor is proposed, which consists of a Fabry–Perot interferometer (FPI) filled with a polymer film of polydimethylsiloxane (PDMS). The FPI structure is fabricated by splicing a section of hollow core fiber (HCF) to the end-face of a lead-in single mode fiber (SMF). Then, the PDMS is filled into the HCF which acts as a light reflector and a diaphragm to detect external pressure variation. As a result, the length of the FPI cavity and the thickness of the PDMS are 137.8 μm and 33.8 μm, respectively. Experimental results indicate that the sensor’s wavelength exhibits a linear response to the hydraulic pressure, which function is described as y = ?7.35 × 10?3x + 1536.395. Here, x and y represent the hydraulic pressure and the wavelength, respectively. The pressure sensitivity is up to ?7.35 nm/kPa. Besides, a temperature compensation method based on a fiber Bragg grating is proposed to eliminate the influence of temperature. Experiments show that the scheme can effectively eliminate the influence of temperature and achieve accurate measurement of hydraulic pressure.
关键词： Fabry-Perot interferometer,polydimethylsiloxane,temperature compensation,hydraulic pressure sensor,fiber Bragg grating
更新于2025-09-12 10:27:22
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Free Space Optical Communication (System Design, Modeling, Characterization and Dealing with Turbulence) || 6. Quality metrics and reliability analysis of ground-to-ground free space laser communication in different weather conditions together with beam steering system
摘要： Over the past two decades Free Space Optical Communication (FSOC) has become more and more interesting as an adjunct or alternative to Radio Frequency (RF) communication. Optical wave propagation in an FSOC channel is severely affected by turbulent atmospheric parameters and they lead to the degradation of the data transmission quality and reliability. Among the various atmospheric effects, beam wandering is the main cause for major power loss and cannot be solved without incorporation of a Beam Wandering Compensation (BWC) control system. Therefore, a closed form treatment describing beam wandering effect mitigation is required. Simplex FSOC data transmission (data rate is 155 Mbps) transmitter-receiver experimental setups are established for the data link range of 0.5 km at an altitude of 15.25 m at the college campus. A near IR 850 nm optical source is used for data transmission. The more accurate values of atmospheric attenuation (Atten) and turbulence strength (C2n) are obtained using the new models developed according to local weather data. The transmittance of the FSOC channel is calculated using the estimated atmospheric attenuation. The methods of measuring the Q-factor and Bit Error Rate (BER) by postprocessing the received signal are described and used to validate the performance of the FSOC system. The improvements on received signal strength and centroid stability by incorporating the BWC control system are analyzed with various communication key parameters in the very weak to very strong atmospheric turbulence conditions. The average BER at a value of 9.82 ? 10?9 is maintained with the Q-factor value of ≈ 6 in almost all atmospheric turbulence conditions with compensating beam wandering effects, i.e. pointing error losses. Evidence of the suitability and effectiveness of the developed controller in terms of received power (Pr), transmittance (T), eye diagram, Q-factor, Signal to Noise Ratio (SNR), BER, link margin and decoding decision threshold values are comprehensively analyzed through experimental results and reported in this chapter.
关键词： atmospheric turbulence,Beam Wandering Compensation (BWC),Q-factor,Signal to Noise Ratio (SNR),Bit Error Rate (BER),Free Space Optical Communication (FSOC)
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE 4th Optoelectronics Global Conference (OGC) - Shenzhen, China (2019.9.3-2019.9.6)] 2019 IEEE 4th Optoelectronics Global Conference (OGC) - The Optimization Control of Model-Based Friction Compensation and Experimental Test for the Laser Communication System
摘要： Axis mechanical system can influence the accuracy of the terminal motion control system. Friction can cause the steady state error and making the system response slow. Communication terminal will benefit from the friction compensation in the servo system. The performance of the servo system using the LuGre friction model for compensation is better than the same system without friction compensation. The high performance requirements for the terminal control system can be achieved. This paper describes the nonlinear friction mathematical model, the estimation of the model parameters and reports and analyzes friction compensation experiment. For an actual terminal motor drive system, the nonlinear friction characteristics of the terminal control system based on the friction compensation is presented. The effectiveness of this control technique is discussed and investigated.
关键词： control system,communication terminal,friction compensation,LuGre model
更新于2025-09-12 10:27:22
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A laser current control algorithm to avoid color distortion in laser projection displays
摘要： Laser display technology has gradually become an important solution for large screen display. As a mature lighting technology in recent decades, phosphor has been widely used in the field of lighting and display. As a solid-state light source, it has the advantages of low power consumption, environmental protection, rich color, and dynamic modulation. The luminescent efficiency of phosphors varies with temperature, which results in the nonlinearity of phosphor emission when the light source is dynamically modulated and the color temperature drift of the display image. In this paper, a control model of color temperature of laser TV display changing with laser current and temperature is established. The color temperature of laser TV is corrected by using current compensation control algorithm. The problem of color temperature drift caused by the change of phosphor conversion efficiency with temperature is solved. The color temperature deviation is 1118 K in the luminance range of the light source before compensation. By compensating and controlling the laser current, the ratio of blue light and phosphor is constant when the luminance changes, thus ensuring the color temperature constant when the luminance of the laser light source changes. The color temperature deviation is 50 K in the luminance range. By analyzing the different luminance of the display image, the stability of the color temperature is improved.
关键词： laser phosphor,color distortion,dynamic compensation
更新于2025-09-12 10:27:22
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[IEEE 2019 26th Saint Petersburg International Conference on Integrated Navigation Systems (ICINS) - Saint Petersburg, Russia (2019.5.27-2019.5.29)] 2019 26th Saint Petersburg International Conference on Integrated Navigation Systems (ICINS) - Study of Laser Gyro Temperature Compensation Technique on LINS
摘要： Laser gyroscope is a high precision optical angular rate sensor. The stability of the Laser gyro output directly affects the navigation accuracy of the laser gyro inertial navigation system (LINS). On base of analyzing the error model of LINS, the temperature compensation model of laser gyroscope is established. The temperature compensation model of the gyro bias is established and the gyro bias is compensated with the method of subsection Hermite interpolation. Data collection and temperature compensation experimentations of the laser gyro in different temperature conditions are designed and completed. The output of the laser gyro is compensated off-line by the gyro pulse compensation model. The gyro bias is recalculated using the compensated gyro calibration data in order to validate the affection of the gyro temperature compensation method. Experiments show that the compensation effect of this temperature compensation method is visible. The laser gyro static output stability is improved more than 3 times at room temperature. Experiments show that this method has high engineering application value.
关键词： Hermite interpolation,temperature compensation technique,subsection,Laser gyro
更新于2025-09-12 10:27:22
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High-precision femtosecond laser beam shaping in material processing
摘要： Laser beam shaping is the process of modulating the amplitude and phase of a laser beam. With the development of the spatial light modulator, laser beam shaping can modulate the light field to arbitrary pattern dynamically via the computer-generated hologram (CGH). Otherwise, femtosecond laser is widely used in material processing owing to its high peak power, low hot effect and nonlinear effects. However, femtosecond laser is not strictly monochromatic, which will introduce dispersion when femtosecond laser diffracted by a spatial light modulator, and deteriorate the effect of beam shaping. Here we present a method of high-precision femtosecond laser beam shaping. Experimental results confirm that the proposed method can be used to shape femtosecond laser beams into arbitrary patterns in the whole field of view (FOV) with the resolution near the optical diffraction limit.
关键词： spatial light modulator,beam shaping,dispersion compensation,femtosecond laser,material processing
更新于2025-09-12 10:27:22
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An Efficient DFG Induced Wavelength Exchanged-OPC Using Only Two Ti:PPLN Waveguides with Single Pump Configuration
摘要： An unconventional single pump configuration of Wavelength Exchanged Optical Phase Conjugation (WE-OPC) through Difference Frequency Generation (DFG) employing two identical Ti:PPLN waveguides having same grating period and a single pump source is theoretically analyzed and simulated resulting in higher conversion efficiency of OPC.WE-OPC has been found very effective in extenuating nonlinearity and inflating spectral efficiency in optical transmission systems. The proposed WE-OPC enabled WDM optical transmission system modeled as a wavelength converter has been simulated with 10 channels offering much higher conversion efficiencies of about 3.3 dB and 3.49 dB for higher frequency band to lower frequency band and vice versa respectively.
关键词： Fiber optics communications,Dispersion compensation devices,Fiber optics and optical communications,Optical Phase conjugation,Wavelength conversion devices
更新于2025-09-12 10:27:22