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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) - Laser Illumination Designs for Snapshot Multi-Spectral-Line Imaging
摘要： For multi-spectral imaging, both acquisition time of the spectral image set and the spectral bandwidth of each image have to be minimized. Ultimate performance can be achieved if the set of monochromatic (single-wavelength) spectral images is obtained with a single snapshot - a technique provisionally called “snapshot multi-spectral-line imaging” or SMSLI. Using contemporary RGB colour cameras, up to three spectral line images can be extracted from a snapshot image data cube at specific illumination that comprises only three spectral lines, each of them positioned within one of the detection bands (R, G or B) [1]. Techniques able to provide more spectral line images are under development, and optimal design enabling uniform illumination of target simultaneously by several laser lines is a key challenge.
关键词： multi-spectral imaging,laser illumination,SMSLI,snapshot multi-spectral-line imaging,uniform illumination
更新于2025-09-11 14:15:04
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[IEEE 2019 International Conference on Opto-Electronics and Applied Optics (Optronix) - Kolkata, India (2019.3.18-2019.3.20)] 2019 International Conference on Opto-Electronics and Applied Optics (Optronix) - Design of High-Performance LED Based Integrating Sphere for Illumination & Communication
摘要： An integrating sphere has been specially designed using multiple white light LEDs mounted on both the inner and outer surfaces of the sphere to create improved uniform illumination inside a computer laboratory room. The LEDs are simultaneously used as optical transmitters of trans-receiver systems for indoor optical wireless communication. More uniformity of light helps to develop better access to wireless communication systems, comfortable movement inside the room and reduced shadowing effect in wireless communication. One integrating sphere fitted with LED arrays divided among outer and the inner surfaces of the sphere is able to create ideal uniformity conditions for illumination and data communication within a volume (3 x 3 x 3) m3 of laboratory space. The system is capable of bidirectional full-duplex communication using IR LEDs as source for uplink and silicon photodiodes as receivers for optical wireless communication links. The theory and the design principles of the integrating sphere and the optical wireless communication link design would be presented.
关键词： integrating sphere,optical communication,wireless communication,uniform illumination,white light LED
更新于2025-09-11 14:15:04
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High‐Resolution Inkjet Printing of Quantum Dot Light‐Emitting Microdiode Arrays
摘要： The direct printing of microscale quantum dot light-emitting diodes (QLEDs) is a cost-effective alternative to the placement of pre-formed LEDs. The quality of printed QLEDs currently is limited by nonuniformities in droplet formation, wetting, and drying during inkjet printing. Here, optimal ink formulation which can suppress nonuniformities at the pixel and array levels is demonstrated. A solvent mixture is used to tune the ejected droplet size, ensure wetting, and provoke Marangoni flows that prevent coffee stain rings. Arrays of green QLED devices are printed at a resolution of 500 pixels in.?1 with a maximum luminance of ≈3000 cd m?2 and a peak current efficiency of 2.8 cd A?1. The resulting array quality is sufficient to print displays at state-of-the-art resolutions.
关键词： light-emitting diodes,quantum dots,uniform pixel arrays,inkjet printing,high resolution
更新于2025-09-11 14:15:04
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[IEEE 2018 22nd International Conference on System Theory, Control and Computing (ICSTCC) - Sinaia, Romania (2018.10.10-2018.10.12)] 2018 22nd International Conference on System Theory, Control and Computing (ICSTCC) - Uniform Extended Local Ternary Pattern for Content Based Image Retrieval
摘要： The retrieval of images depending on content is a recurrent research topic in medical imaging. Most CBIR systems are designed to help physicians in the diagnostic of the pathologies. Image retrieval according to the content of the texture features can be performed through various methods developed so far. Local texture features are very beneficial for the analysis of the texture, thus, they are extensively used in image retrieval. The original LBP is improved in this paper with a new addition for CBIR called uniform extended local ternary pattern (UELTP). The method decomposes the image into objects; local texture features are extracted and stored into n-dimensional texture feature vectors. Then, the images are frequently obtained from a huge database dedicated for images using these vectors. In this paper, the performance of LBP descriptor, LTP and ELTP are evaluated for CBIR. According to the results, uniform extended local ternary pattern more accurate than other descriptors in terms of image retrieval.
关键词： CBIR,Feature Extraction,LBP,LTP,uniform patterns
更新于2025-09-11 14:15:04
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Review of the solar flux distribution in concentrated solar power: non-uniform features, challenges, and solutions
摘要： Concentrated solar flux distribution in the concentrated solar power (CSP) systems is extremely non-uniform, which can lead to high local temperature and large temperature gradient in solar receivers that will cause great challenges for the safety and efficient operation of the system. This paper introduces the non-uniform flux features in four CSP technologies including the parabolic-trough collector, the linear Fresnel collector, the solar power tower, and the parabolic-dish collector. Challenges including degeneration of the materials, thermal stress and deformation, and overburning are summarized. The corresponding solutions proposed to tackle these challenges are emphatically reviewed, and a recommendation for the optimization of the solar collector is provided from this review, which is that the solar flux distribution and the heat transfer ability of the heat transfer fluid (HTF) should match with each other as well as possible. From this point of view, the existing solutions are classified into two groups. One is optimizing the heat transfer ability of the HTF to match with the flux distribution, which is called the passive approach. The other is homogenizing the flux distribution to match with the identical heat transfer ability of the HTF, which is called the active approach. This review can help to have a better understanding of the non-uniform solar flux features in CSPs, and provide guidance for solving the corresponding challenges.
关键词： Non-uniform temperature,Solar receiver,Concentrated solar power,Non-uniform solar flux,Challenges and solutions,Solar concentrator
更新于2025-09-10 09:29:36
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Bistatic ISAR Imaging for Non-Uniformly Rotating Targets
摘要： When a target undergoes non-uniform rotational motion (RM), conventional motion compensation (MOCOM) approaches for monostatic inverse synthetic aperture radar (ISAR) systems fail to correct the non-uniform RM error in bistatic radar systems; this failure is caused by nonlinear phase relationships between scatterers in bistatic ISAR (Bi-ISAR) systems. To address this problem, in this paper, we propose a new MOCOM framework for Bi-ISAR imaging of non-uniformly rotating targets. In the proposed method, a newly devised correction is performed to ensure successful RM compensation, followed by translational motion compensation (TMC). Because the phase relationships of the scatterers become virtually linear after this correction, non-uniform RM can be successfully converted into uniform RM. Namely, using the proposed method, translational and rotational motion errors are correctly removed, and focused Bi-ISAR images are obtained even for a target involved in non-uniform RM. Further, for more effective use of Bi-ISAR images, a method to restore sheared Bi-ISAR images is exploited in the proposed framework. In the simulations and experiments, we determined that the proposed method can provide high-quality Bi-ISAR images for non-uniformly rotating targets.
关键词： rotational motion compensation (RMC),Autofocus,rotational motion (RM),motion compensation (MOCOM),bistatic inverse synthetic aperture radar (Bi-ISAR) imaging,non-uniform rotational motion
更新于2025-09-10 09:29:36
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Uniform field coil design based on the target-field method in miniature atomic sensors
摘要： This paper presents the design of a uniform ?eld coil based on the target-?eld method, which offers an innovative in miniature atomic sensors. A selected uniform ?eld cubical target region is located inside a cylinder with the surface comprised of coil windings. Firstly, the current density was de?ned with unknown coef?cients, and then a straightforward approach was used to obtain these coef?cients via solving a matrix constructed by selecting ?eld points in the target region. Subsequently, using the stream-function, the winding patterns of the coils are generated. Compared to the traditional coil design method, this method effectively solves the inconsistency between the uniform ?eld areas and the sensor structures, by prede?ning the size of the coil surface before calculating the current distribution. It also avoids the cumbersome calculation process caused by the multi-order Taylor expansion based on the traditional method. Furthermore, a current density formula was expanded by trigonometric series, which is particularly suitable for a cylindrical coil system with the uniform internal ?eld. The theoretical accuracy can be greatly improved by choosing an optimal order of the trigonometric series. To prove its performance, a contrast with a Lee-Whiting coil is proposed. In addition, the utilized coil was manufactured by Flexible Printed Circuit technology and magnetic ?eld uniformities were veri?ed by an actual test using a ?uxgate magnetometer.
关键词： miniature atomic sensors,The target-?eld method,current density,uniform ?eld coil
更新于2025-09-10 09:29:36
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On crack propagation monitoring by using reflection spectra of AFBG and UFBG sensors
摘要： Due to their light weight, small size and immunity to electromagnetic interference, Fiber Bragg Gratings (FBG) have shown great potential in structural health monitoring (SHM) area. Ordinarily, FBGs are used as the quasi-distributed sensors to detect structural damage by central wavelengths shifting, which has robust problem in real engineering application. It is found that the FBG reflection spectra can also be distorted with the non-uniform strain field caused by crack. Multiple indices can be extracted from the reflection spectra which can provides more information on the crack propagation. However, till now no researches have been investigated regarding the behaviors of different kinds of FBGs for crack propagation monitoring based on the FBG reflection spectra. In this paper, behaviors of the apodized FBG (AFBG) and the uniform FBG (UFBG) sensors for structural crack propagation monitoring are investigated. The reflective spectral behaviors of both UFBG and AFBG sensors under crack-generated non-uniform strain are illustrated by simulation and experiment. Three spectra indices, namely the central wavelength shift, the ratio of side lobe to main lobe and the information entropy, are proposed to indicate the propagation of the crack. The results show the UFBG sensors have better performance than the AFBG sensors which are more suitable for crack propagation monitoring.
关键词： crack propagation monitoring,uniform fiber Bragg gratings,apodized fiber Bragg gratings,structural health monitoring,spectral distortion
更新于2025-09-10 09:29:36
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Dynamical stochastic resonance for non-uniform illumination image enhancement
摘要： Images taken under poor illumination conditions have low contrast and dark tones. General dark image enhancement algorithms cannot effectively enhance these images without introducing over-enhancement, detail loss, and noise amplification. In this study, a simple and fast enhancement technique of non-uniform illumination images is proposed based on dynamical stochastic resonance (DSR). The low-contrast images are enhanced through the nonlinear iteration by solving monostable Langevin equation. Iteration parameters are dynamically adjusted according to the intensity distribution of the original images, which ensure the balance of visibility and naturalness in the entire areas. A threshold is defined to automatically confirm the optimal outputs. The enhanced image is obtained by fusing the DSR result, original component, and illumination compensation component. The computational time, no-reference perceptual quality assessment, and lightness order error are measured to evaluate the performance of experimental results. The subjective and objective comparison with state-of-the-art methods shows that our method performs well to enhance the non-uniform illumination images with a low-computational complexity.
关键词： non-uniform illumination,Langevin equation,nonlinear iteration,image enhancement,dynamical stochastic resonance
更新于2025-09-10 09:29:36
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Comparing the uniformity of light glass fiber felt based on process improvement, microstructural forming mechanism and physical properties
摘要： Light glass fiber felt (density 10 kg/m3), a porous composite consisting of 83% glass fibers (the average diameter 1.5 mm) and 17% phenolic resin, is usually used to increase sound insulation in the aerospace industry. The purpose of this research is further to improve the uniformity of light glass fiber felts by process optimization, analysis of microstructural forming mechanisms and physical properties. Light glass fiber felt is produced by the flame blowing process. The results show that process optimization can effectively improve the uniformity of light glass fiber felt. Light glass fiber felt exhibits a micro-layer structure seen as consisting of a number of ‘‘three-layer’’ structures, that is dense (more fibers)-loose (less fibers)-dense structure. In addition, process optimization can improve the stability of permeation rate and enhance sound insulation performance, which makes light glass fiber felt an excellent sound insulator.
关键词： uniform,light glass fiber felt,physical properties,sound insulation,microstructure,permeation rate
更新于2025-09-10 09:29:36