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77-GHz mmWave antenna array on liquid crystal polymer for automotive radar and RF front-end module
摘要： This paper introduces a low‐cost, high‐performance mmWave antenna array module at 77 GHz. Conventional waveguide transitions have been replaced by 3D CPW‐microstrip transitions which are much simpler to realize. They are compatible with low‐cost substrate fabrication processes, allowing easy integration of ICs in 3D multi‐chip modules. An antenna array is designed and implemented using multilayer coupled‐fed patch antenna technology. The proposed 16 × 16 array antenna has a fractional bandwidth of 8.4% (6.5 GHz) and a 23.6‐dBi realized gain at 77 GHz.
关键词： broadband transition,3D transition,mmWave antenna array,automotive radar module,proximity-coupled patch antenna
更新于2025-09-23 15:22:29
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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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Construction of Ag@AgCl decorated TiO2 nanorod array film with optimized photoelectrochemical and photocatalytic performance
摘要： A novel Ag@AgCl/TNR film photocatalyst was successfully obtained by a facile multistep route. Using a well-organized TiO2 nanorod array (TNR) film as the starting material, Ag nanoparticles were uniformly deposited on the TNR film via a photochemical reduction, and in situ oxidation of Ag by FeCl3 solution resulted in the formation of Ag@AgCl/TNR film. The structure, morphology, composition, optical, photocatalytic and photoelectrochemical properties of the obtained films were investigated in detail. The results showed that core-shell Ag@AgCl can effectively promote the transfer of photo-generated electron-hole pairs, suppress their recombination, and enhance the visible light absorption. The Ag@AgCl/TNR film with 60 min oxidation time (S60) showed the highest photocurrent and best transfer performance of interfacial electrons in the electrochemical impedance spectroscopy (EIS) Nyquist plots. For the photodegradation of methyl orange (MO), the S60 exhibited the highest photocatalytic efficiency (90.8%) and good stability under visible light irradiation, which can be comparable and even better than the previous reports. A detailed photocatalytic mechanism was proposed on the basis of the fact that Ag nanoparticles with surface plasma resonance (SPR) can be excited by visible light and this unique structure effectively transfers photo-generated electrons from Ag to TiO2 conduction band, accomplished by the transfer of compensative electrons from a donor (Cl-) to Ag nanoparticles.
关键词： Nanorod array,Photocatalytic activity,Photocurrent,TiO2,Ag@AgCl
更新于2025-09-23 15:22:29
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Hierarchical rutile/anatase TiO2 nanorod/nanoflower thin film: Synthesis and characterizations
摘要： Hierarchical TiO2 nanorod/nano?ower thin ?lm was synthesized on ?uorine doped tin oxide glass via hydrothermal and aqueous chemistry methods. According to ?eld emission scanning electron microscopy results, the thin ?lm was crack-free and uniform. Primary nanorods had an average diameter of 95 nm and a length of 2 μm. They were perpendicular to the substrate owing to the TiO2 prenucleation. Growth of the nano?owers on the nanorods could increase both the speci?c surface area and roughness. X-ray di?raction and Raman spectroscopy showed that the nanorods were rutile; while the nano?owers were anatase. E?cient electron transfer from anatase to rutile could therefore occur. According to the di?use transmittance spectroscopy examination, the light harvesting rate was ameliorated and the band gap energy reduced to 2.83 eV. This was attributed to the F-doping the sample during synthesis. The enhancement of the photoelectrochemical activity allowed substitution of the TiO2 nanorod/nano?ower thin ?lm for the traditional TiO2 nanorods usually used in solar cells, sensors, and photocatalytic systems.
关键词： Aqueous chemistry,Nanorod array,Rutile/anatase TiO2,Hydrothermal,Nano?ower
更新于2025-09-23 15:22:29
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Maskless lithography based on digital micromirror device (DMD) and double sided microlens and spatial filter array
摘要： A new type of maskless lithography system based on digital mirror device (DMD) is proposed, constructed, and experimentally demonstrated. It includes a pin-hole array sandwiched by two microlens arrays on each side, known as double-sided microlens/spatial-filter array (D-MSFA), and aligned with a DMD. Ultraviolet (UV) light reflected by DMD is first collected by the first microlens array, filtered through the pin-hole array, and then re-focused by the second microlens array into a UV spot array. Along with an obliquely scanning method, this D-MSFA/DMD-based maskless lithography system can perform not only 2D but also 3D UV patterning. Experimental testing successfully generates complicated patterns with a minimum line-width of 3.36 μm. Direct 3D patterning and 3D microfabrication are also experimentally demonstrated on a photoresist layer. Excellent profile accuracy and surface structure qualities are observed with great potentials for future 2D and 3D microfabrication in a maskless manner.
关键词： Microlens array,Maskless lithography,Digital mirror device (DMD),3D microfabrication
更新于2025-09-23 15:22:29
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Effectiveness of phased array focused ultrasound and active infrared thermography methods as a nondestructive testing of Ni-WC coating adhesion
摘要： The substrate/coating adhesion is a crucial parameter conditioning the quality of coating and its durability in service. For this reason, an inspection of the coating integrity, in particular, the presence of adhesion defects will be of great importance. The adhesion inspection is usually ensured by destructive methods, such as traction, interfacial indentation, four-point bending, testing scratch, etc. However, it is currently hampered by the absence of a satisfactory non-destructive method. Among the non-destructive testing technologies widely used in the industrial field, there are X-ray diffraction, ultrasonic inspection, and infrared thermography. In this paper, two methods are investigated: ultrasonic inspection, which becoming more efficient, especially with the emergence of phased array systems that allow to investigate different inspection angles and focusing depths, and the active infrared thermography. Experiments were performed on metallic coatings deposited on a mild steel substrate. Coatings were containing artificial defects (flat bottom holes with different diameters) at the interface and others were exempts of defects. Longitudinal waves with specific delay laws were generated through a phased array contact transducer (5 MHz of central frequency). Experimental results show that the ultrasonic method allows detecting and sizing defects with a diameter of 1 mm located in thick coatings.
关键词： Substrate/coating adhesion,phased array,defects,detection,nondestructive testing,coating
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE Photonics Conference (IPC) - Reston, VA (2018.9.30-2018.10.4)] 2018 IEEE Photonics Conference (IPC) - High-Power Photonic Phased Array Antennas
摘要： We review recent work on a new antenna concept— the high-power photonic phased array. By integrating high-power photodiodes proximal to the transmit aperture’s radiating elements, dense, lightweight, and broadband array designs are realized. Several manifestations of this idea are discussed, emphasizing different application-specific design choices.
关键词： RF photonics,ultra-wideband (UWB),photonic antenna,phased array antenna,5G,high-power photodiode,millimeter wave (mmW)
更新于2025-09-23 15:22:29
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A shared aperture 1-bit metasurface for orbital angular momentum multiplexing
摘要： In this letter, a shared aperture 1-bit metasurface for orbital angular momentum (OAM) multiplexing is studied. A phased array antenna fed by the phase shift network is embedded on the reflective aperture of the 1-bit metasurface. The proposed device can work on reflectarray mode from 7.1GHz to 7.5GHz and phased array mode from 7GHz to 7.5GHz. Correspondingly, OAM vortex beam with topological charge l = -1 and l = 1 can be generated. The transmission coefficient between the two working modes is below -30dB and the envelop correlation coefficient (ECC) is quite close to 0, which reveals the excellent isolation and diversity performance. A prototype of the proposed device is fabricated and tested. The measured S parameters and radiation patterns agree well with the simulation results.
关键词： phased array,reflectarray,metasurface,Orbital angular momentum (OAM) multiplexing
更新于2025-09-23 15:22:29
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Joint Color Space GMMs for CFA Demosaicking
摘要： We propose a patch-based algorithm for demosaicking a mosaicked color image produced by color filter arrays commonly used in acquiring color images. The proposed algorithm exploits a joint color space Gaussian mixture model (JCS-GMM) prior for jointly characterizing the patches from red, green, and blue channels of a color image. The inter channel correlations captured by the covariance matrices of Gaussian models are exploited to estimate the pixel values missing in the mosaicked image. The proposed JCS-GMM demosaicking algorithm can be seen as the GMM analogue of the Color-KSVD algorithm, which has produced impressive results in color image denoising and demosaicking. We demonstrate that our proposed algorithm achieves superior performance in the case of Kodak and Laurent Condat’s databases, and competitive performance in the case of IMAX database, when compared with state-of-the-art demosaicking algorithms.
关键词： Color filter array,demosaicking,Bayer pattern,Gaussian mixture models
更新于2025-09-23 15:22:29
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[IEEE OCEANS 2018 MTS/IEEE Charleston - Charleston, SC, USA (2018.10.22-2018.10.25)] OCEANS 2018 MTS/IEEE Charleston - Optimal design of frequency-invariant beamformers for circular arrays
摘要： This paper proposes a optimal method designing frequency-invariant beamformers for circular arrays. First, the desired beampattern is expressed as a general complex-weighted form. Second, the weighting vectors at each frequency are accurately derived by approximating to the desired beampattern from the minimum mean square error perspective, all of which are found to be close-form functions of the desired complex weighting vectors. Third, a multiple optimization problem is formulated, and its solution gives the optimal desired weighting vector subject to different constraints. Finally, the weighting vectors at other frequencies can be directly computed based on the previously derived analytical functions. The proposed method provides flexible schemes to design different optimal frequency-invariant beamformers for circular sensor arrays. The good performance of the proposed method is demonstrated using simulations and experimental results.
关键词： circular sensor array,Frequency-invariant beamforming,multi-constraint optimization
更新于2025-09-23 15:22:29