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- 实验方案
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Programmable Spectral Filter in C-Band Based on Digital Micromirror Device
摘要： Optical ?lters have been adopted in many applications such as recon?gurable telecommunication switches, tunable lasers and spectral imaging. However, most of commercialized ?lters based on a micro-electrical-mechanical system (MEMS) only provide a minimum bandwidth of 25 GHz in telecom so far. In this work, the programmable ?lter based on a digital micromirror device (DMD) experimentally demonstrated a minimum bandwidth of 12.5 GHz in C-band that matched the grid width of the International Telecommunication Union (ITU) G.694.1 standard. It was capable of ?ltering multiple wavebands simultaneously and ?exibly by remotely uploading binary holograms onto the DMD. The number of channels and the center wavelength could be adjusted independently, as well as the channel bandwidth and the output power. The center wavelength tuning resolution of this ?lter achieved 0.033 nm and the insertion loss was about 10 dB across the entire C-band. Since the DMD had a high power handling capability (25 KW/cm2) of around 200 times that of the liquid crystal on silicon (LCoS) chip, the DMD-based ?lters are expected to be applied in high power situations.
关键词： digital micromirror device,optical switch,programmable spectral ?lter
更新于2025-11-28 14:23:57
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Performances of Microwave Photonic Notch Filter Based on Microring Resonator with Dual-drive Modulator
摘要： A tunable microwave photonic notch ?lter with ultrahigh radio frequency (RF) rejection ratio is achieved by using a dual-drive Mach–Zender modulator and a microring resonator. In addition, we dedicated to clarify the mechanisms of the microwave photonic notch ?lters based on a microring resonator under both overcoupled and undercoupled states and the performance differences between these two situations are investigated in detail. Furthermore, the experimental results show that the cancellation microwave photonic notch ?lter with ultrahigh RF rejection ratio can be achieved with both undercoupled and overcoupled microring resonators. Besides, an RF rejection ratio exceeding 50 dB was achieved for a microring resonator with an optical extinction ratio of only 4 dB, where a 46-dB enhancement from optical to RF response is obtained. Also, the bandwidth of the microwave photonic ?lter can tuned from 0.65 to 2.2 GHz by adjusting the coupling ratio of the ring resonator. Meanwhile, by tuning the wavelength of the optical carrier, the ?ltering frequency can be tuned and a tuning range of about 25 GHz was achieved. The implementation is much simpler and more economical compared with previous reports and has great potential in monolithic integration of microwave photonic ?lters on chip.
关键词： Optical ?lter,Microwave photonics,Microring resonator,Integrated optics devices
更新于2025-09-23 15:23:52
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An FPGA-Oriented Algorithm for Real-Time Filtering of Poisson Noise in Video Streams, with Application to X-Ray Fluoroscopy
摘要： In this paper we propose a new algorithm for real-time ?ltering of video sequences corrupted by Poisson noise. The algorithm provides effective denoising (in some cases overcoming the ?ltering performances of state-of-the-art techniques), is ideally suited for hardware implementation, and can be implemented on a small ?eld-programmable gate array using limited hardware resources. The paper describes the proposed algorithm, using X-ray ?uoroscopy as a case study. We use IIR ?lters for time ?ltering, which largely simpli?es hardware cost with respect to previous FIR ?lter-based implementations. A conditional reset is implemented in the IIR ?lter, to minimize motion blur, with the help of an adaptive thresholding approach. Spatial ?ltering performs a conditional mean to further reduce noise and to remove isolated noisy pixels. IIR ?lter hardware implementation is optimized by using a novel technique, based on Steiglitz–McBride iterative method, to calculate ?xed-point ?lter coef?cients with minimal number of nonzero elements. Implementation results using the smallest StratixIV FPGA show that the system uses only, at most, the 22% of the resources of the device, while performing real-time ?ltering of 1024 × 1024@49fps video stream. For comparison, a previous FIR ?lter-based implementation, on the same FPGA, in the same conditions and constraints (1024 × 1024@49fps), requires the 80% of the logic resources of the FPGA.
关键词： Poisson noise,X-ray video?uoroscopy processing,Field-programmable gate array (FPGA),IIR ?ltering,IIR ?lter design,Real-time video ?ltering
更新于2025-09-23 15:22:29
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[IEEE 2019 7th International Renewable and Sustainable Energy Conference (IRSEC) - Agadir, Morocco (2019.11.27-2019.11.30)] 2019 7th International Renewable and Sustainable Energy Conference (IRSEC) - Power Quality Improvement of A Photovoltaic Active Power Filter using A Fuzzy Hysteresis Band Current Controller
摘要： This paper investigates a Fuzzy Hysteresis Band Current Control technique (Fuzzy-HBCC) for a Photovoltaic active power ?lter connected at PCC to the AC grid and a non-linear load. This connection offers good bene?ts of producing PV power as well as ensuring the power quality enhancement. In order to demonstrate the ef?ciency of the proposed system command using Fuzzy-HBCC, Fuzzy Vdc controller and Fuzzy-MPPT controller; several simulation cases have been carried out under an online solar variation, and a variable/?xed ignition angle of the nonlinear load. The proposed Fuzzy band current control technique (Fuzzy-HBCC) is developed and compared by simulation, in a Matlab/Simulink environment, with an adaptive Hysteresis controller (adaptive-HBCC) and a ?xed Hysteresis controller (?xed-HBCC) which require mathematical model determination. The results show the robustness of the proposed Photovotaic active power ?lter system with a better dynamic response and signi?cant reduction in Total harmonic distortion levels even under a sudden variation of the nonlinear load and of solar irradiance.
关键词： photovotaic active power ?lter,fuzzy band current control technique,dynamic response,total harmonic distortion
更新于2025-09-23 15:21:01
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Groove Gap Waveguide Filter Based on Horizontally Polarized Resonators for V-Band Applications
摘要： In this article, resonators based on air-?lled rectangular cavity consisting of one perfect magnetic conductor (PMC) wall and the rest of walls as the perfect electric conductor (PEC) are proposed. The proposed cavity can be engraved in the top or bottom metal plate of a gap waveguide structure, and the PMC wall is realized by the periodic metallic pins located within the gap waveguide geometry. The resonant frequency and electromagnetic (EM) ?eld distribution of the cavity are investigated, and it is shown that the electric ?eld is horizontally polarized with respect to the wave propagation direction. Two bandpass ?lters are designed by inserting the proposed cavity in the cutoff region of the gap waveguide, on the top and bottom plates. In the latter case, all pins are the same, and the cavities and coupling structure are easily implemented by engraving the top plate. Therefore, by using this concept, a common pin plate can be used to implement different passive millimeter-wave devices. For instance, three different ?lters working at 60, 65, and 70 GHz with a common bottom pin plate are designed and fabricated. The measured results show a minimum insertion loss of 1.4, 1.1, and 1.1 dB with 0.83%, 1.4%, and 1.8% fractional bandwidth for the three bandpass ?lter designs, respectively, with aluminum as metal.
关键词： perfect magnetic conductor (PMC),Antenna system,millimeter-wave ?lter,gap waveguide
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Improvement of Ohmic Behavior of Back Contact in ZnSnP <sub/>2</sub> Solar Cells by Inserting Cu <sub/>3</sub> P
摘要： We propose a sampling scheme that can perfectly re- construct a collection of spikes on the sphere from samples of their lowpass-?ltered observations. Central to our algorithm is a gen- eralization of the annihilating ?lter method, a tool widely used in array signal processing and ?nite-rate-of-innovation (FRI) sam- pling. The proposed algorithm can reconstruct spatial samples. For large, this sampling require- ment improves over previously known FRI sampling schemes on the sphere by a factor of four. We showcase the versatility of the proposed algorithm by applying it to three problems: 1) sampling diffusion processes induced by localized sources on the sphere, 2) shot noise removal, and 3) sound source localization (SSL) by a spherical microphone array. In particular, we show how SSL can be reformulated as a spherical sparse sampling problem.
关键词： sparse sampling,spherical harmonics,sphere,Annihilation ?lter,?nite rate of innovavtion,diffusion sampling,shot noise removal,sound source localization
更新于2025-09-23 15:21:01
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Sliding Mode Controller with Integral Action for DC-Link Voltage Control of Grid-Integrated Domestic Photovoltaic Systems
摘要： The grid integration of photovoltaic systems is preferred over the islanded mode of operation as the former does not require additional storage element, hence less maintenance and no chemical pollution. To regulate power exchange between the grid and the photovoltaic system, a robust DC-link voltage controller capable of withstanding the intermittent nature of solar energy and sudden variations in load is inevitable. A proportional–integral controller is used for DC-link voltage control, exhibiting oscillations during steady state and overshoot during transients. However, the conventional sliding mode controller reduces the overshoot at the expense of increased steady-state error. This paper proposes a robust sliding mode controller for DC-link voltage control to reduce steady-state error by incorporating integral action to the conventional sliding mode controller. The harmful effect of chattering phenomenon is minimised by limiting the error in the control variable using a signum function. The added features of the work include an incremental conductance method for obtaining maximum power from the photovoltaic system, instantaneous pq theory-based self-tuning ?lter for the extraction of fundamental component and inverter switching pulse generation using hysteresis current control technique. The grid-integrated photovoltaic system along with all features is modelled and simulated in MATLAB/Simulink platform. The results of numerical simulations carried out for various system conditions illustrate that the proposed controller provides superior performance when compared to proportional integral controller and conventional sliding mode controller in terms of harmonic compensation, power ?ow balance and speed of response at all system conditions.
关键词： PV system,Sliding mode control with integral action,Grid integration,Shunt active power ?lter,Renewable energy
更新于2025-09-23 15:21:01
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Broadband Plasmonic Polarization Filter Based on Photonic Crystal Fiber with Dual-Ring Gold Layer
摘要： Polarization ?lter is a very important optical device with extinction characteristics. Due to the design ?exibility of photonic crystal ?bers and the high excitation losses of the gold layer, the polarization ?lter based on the photonic crystal ?ber and surface plasmonic resonance e?ect is widely studied. Considering these, we present a simple and high-performance polarization ?lter using the ?nite element method. Numerical simulations show that there is a large di?erence in energy between the two polarization directions by reasonable adjustment of the structural parameters, the con?nement loss in the x-pol direction is less than that in the y-pol direction, which is suitable to realize a broadband polarization ?lter. When the ?ber length is 2 mm, the extinction ratio peak can reach ?478 dB, and the bandwidth with the extinction ratio better than ?20 dB is 750 nm, which covers communication wavelengths of 1.31 μm and 1.55 μm (1.05–1.8 μm). It also has a low insertion loss of 0.11 dB at 1.31 μm and 0.04 dB at 1.55 μm. In addition, our design has high feasibility in fabrication and better tolerance. The proposed ?lter with compactness, high extinction ratio, broad bandwidth, and low insertion loss would play an important role in the sensing detection, bio-medical, and telecommunication ?eld.
关键词： extinction ratio,photonic crystal ?ber,con?nement loss,polarization ?lter,surface plasmon resonance
更新于2025-09-23 15:21:01
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[Lecture Notes in Computer Science] Pattern Recognition and Computer Vision Volume 11256 (First Chinese Conference, PRCV 2018, Guangzhou, China, November 23-26, 2018, Proceedings, Part I) || Robust Crack Defect Detection in Inhomogeneously Textured Surface of Near Infrared Images
摘要： Robust crack defect detection in solar cells has been challenging because of the inhomogeneously textured surface, low contrast between crack defect and background, the diversity of crack types, and so on. To overcome these challenges, this paper presents a new robust crack defect detection scheme for multicrystalline solar cells. Firstly, a steerable evidence ?lter is designed to process EL image to obtain the response map, which enhances the contrast between crack and background and provides evidence for the presence of crack defect. Secondly, complete crack extraction from the response map is employed. Finally, the complete crack can be located in the inspection image by the crack skeleton extraction. Experimental results on defective and defect-free EL images show that the proposed scheme is robust, and various cracks can be effectively detected, which outperforms the previous methods.
关键词： Crack defect,Inhomogeneous texture,Steerable evidence ?lter
更新于2025-09-23 15:21:01
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Defects modes in one-dimensional photonic filter star waveguide structure
摘要： In this work, by the formalism of the interface response theory, we study the existence of defects’ modes in the transmission spectrum of a one-dimensional photonic star waveguide (SWG) structure. The perfect structure presents large forbidden bands (gaps) that come from the periodicity of the system and the resonance states of the grafted lateral branches which play the role of the resonators. The defects modes result from the presence of the defects of the lateral branches level located in two different sites. The behavior of the defects’ modes is analyzed as a function of the defects’ lengths, the number of defectives resonators, the positions of the defects’ and the number of sites. This system can be considered as a selective ?lter with high performance.
关键词： Electromagnetic ?lter,Green Function,Star waveguide structure,Defects modes,Gaps
更新于2025-09-23 15:21:01