- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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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) - Photovoltaic Inverter Momentary Cessation: Recovery Process is Key
摘要： Positron emission tomography (PET) images are typically reconstructed with an in-plane pixel size of approximately 4 mm for cancer imaging. The objective of this work was to evaluate the effect of using smaller pixels on general oncologic lesion-detection. A series of observer studies was performed using experimental phantom data from the Utah PET Lesion Detection Database, which modeled whole-body FDG PET cancer imaging of a 92 kg patient. The data comprised 24 scans over 4 days on a Biograph mCT time-of-flight (TOF) PET/CT scanner, with up to 23 lesions (diam. 6–16 mm) distributed throughout the phantom each day. Images were reconstructed with 2.036 mm and 4.073 mm pixels using ordered-subsets expectation-maximization (OSEM) both with and without point spread function (PSF) modeling and TOF. Detection performance was assessed using the channelized non-prewhitened numerical observer with localization receiver operating characteristic (LROC) analysis. Tumor localization performance and the area under the LROC curve were then analyzed as functions of the pixel size. In all cases, the images with ～2 mm pixels provided higher detection performance than those with ～4 mm pixels. The degree of improvement from the smaller pixels was larger than that offered by PSF modeling for these data, and provided roughly half the benefit of using TOF. Key results were confirmed by two human observers, who read subsets of the test data. This study suggests that a significant improvement in tumor detection performance for PET can be attained by using smaller voxel sizes than commonly used at many centers. The primary drawback is a 4-fold increase in reconstruction time and data storage requirements.
关键词： Image quality assessment,PET/CT reconstruction,PET/CT,image reconstruction
更新于2025-09-19 17:13:59
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Laser hair removal following forehead flap for nasal reconstruction
摘要： The forehead flap is a dependable option for nasal reconstruction owing to its reliability and anatomic likeness to nasal skin. For patients with low hairlines, the vertical design of the paramedian forehead flap can intrude into the scalp, thus incorporating hair into the nasal reconstruction. The inadequate length of the forehead flap or shift to an oblique design may result in eyebrow elevation and asymmetry. Therefore, laser hair removal (epilation) on the forehead flap has been proposed to improve esthetic results. An alexandrite laser (755 nm, 10 to 20 ms, 18-mm spot size) with a Dynamic Cooling Device? (DCD?) cooling system was used for hair removal in 22 patients (16 male and 6 female patients) after nasal reconstructions using forehead flaps from December 2011 to September 2016. All patients received cryogen spray cooling laser treatment (CSC-LT). The mean follow-up period was 24 months, with a range between 18 and 50 months. The average duration of treatment was 1.8 months (range, 1–5 months). The energy density ranged from 14 to 18 J/cm2 with an average of 17.2 J/cm2. The number of treatments ranged from 2 to 4 (mean 2.8). Patients had satisfactory esthetic results over 11.1 months (range, 8–18 months). Residual white hairs were observed in 3 patients, and 4 patients had tiny black residual hairs without deteriorating cosmesis. Using an alexandrite laser to remove hair on the forehead is safe and reliable in nasal reconstruction with superior recipient site cosmesis.
关键词： Hair removal,Epilation,Nasal reconstruction,Forehead flap,Laser
更新于2025-09-19 17:13:59
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Low-Complexity Power-Balancing-Point Based Optimization for Photovoltaic Differential Power Processing
摘要： With the steadily increasing spatial resolution of synthetic aperture radar images, the need for a consistent but locally adaptive image enhancement rises considerably. Numerous studies already showed that adaptive multilooking, able to adjust the degree of smoothing locally to the size of the targets, is superior to uniform multilooking. This study introduces a novel approach of multiscale and multidirectional multilooking based on intensity images exclusively but applicable to an arbitrary number of image layers. A set of 2-D circular and elliptical ?lter kernels in different scales and orientations (named Schmittlets) is derived from hyperbolic functions. The original intensity image is transformed into the Schmittlet coef?cient domain where each coef?cient measures the existence of Schmittlet-like structures in the image. By estimating their signi?cance via the perturbation-based noise model, the best-?tting Schmittlets are selected for image reconstruction. On the one hand, the index image indicating the locally best-?tting Schmittlets is utilized to consistently enhance further image layers, e.g., multipolarized, multitemporal, or multifrequency layers, and on the other hand, it provides an optimal description of spatial patterns valuable for further image analysis. The ?nal validation proves the advantages of the Schmittlets over six contemporary speckle reduction techniques in six different categories (preservation of the mean intensity, equivalent number of looks, and preservation of edges and local curvature both in strength and in direction) by the help of four test sites on three resolution levels. The additional value of the Schmittlet index layer for automated image interpretation, although obvious, still is subject to further studies.
关键词： image analysis,image reconstruction,image representations,image edge analysis,digital ?lters,Adaptive ?lters,image enhancement,synthetic aperture radar (SAR)
更新于2025-09-19 17:13:59
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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) - Ultrafast Light Source at 1.8 ??m Based on Thulium-Doped Fibers for Three-Photon Microscopy
摘要： Optical tomographic imaging requires an accurate forward model as well as regularization to mitigate missing-data artifacts and to suppress noise. Nonlinear forward models can provide more accurate interpretation of the measured data than their linear counterparts, but they generally result in computationally prohibitive reconstruction algorithms. Although sparsity-driven regularizers significantly improve the quality of reconstructed image, they further increase the computational burden of imaging. In this paper, we present a novel iterative imaging method for optical tomography that combines a nonlinear forward model based on the beam propagation method (BPM) with an edge-preserving three-dimensional (3-D) total variation (TV) regularizer. The central element of our approach is a time-reversal scheme, which allows for an efficient computation of the derivative of the transmitted wave-field with respect to the distribution of the refractive index. This time-reversal scheme together with our stochastic proximal-gradient algorithm makes it possible to optimize under a nonlinear forward model in a computationally tractable way, thus enabling a high-quality imaging of the refractive index throughout the object. We demonstrate the effectiveness of our method through several experiments on simulated and experimentally measured data.
关键词： Optical phase tomography,beam propagation method,compressive sensing,total variation regularization,stochastic proximal-gradient,sparse reconstruction
更新于2025-09-19 17:13:59
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Reconstruction of 3D structure for nanoscale biological objects from experiments data on super-bright X-ray free electron lasers (XFELs): dependence of the 3D resolution on the experiment parameters
摘要： The ability to investigate 3D structure of biomolecules, such as proteins and viruses, is essential in biology and medicine. With the invention of super-bright X-ray free electron lasers (e.g. European XFEL and Linac Coherent Light Source (LCLS)) the Single Particle Imaging (SPI) approach allows to reconstruct 3D structures from many 2D diffraction images produced in the experiment by X-rays scattered on the biomolecule exposed in different orientations. In the same time, there are still many challenging problems in experiment setup, sample preparation and injection, which limit number and quality of obtained diffraction patterns and, consequently, limit achievable resolution of recovered 3D structure. However even with the current experimental limitations it is possible to reconstruct 3D structures of some large biomolecules. An important question arises: what range of 3D resolution is possible to achieve under experimental conditions available now. We investigated how the number and quality of diffraction images affect the 3D resolution. First the SPI experiment was simulated and reconstructed with the Dragonfly software. Then we analyzed how the number of diffraction images and the beam intensity affect the final 3D resolution. We come to the following conclusions: 1) starting from the beam intensity value (fluence) equal to 3×1012 photons/μm2 the resolution becomes to be almost constant; 2) the resolution strongly depends on the number of diffraction patterns. More than 10 000 diffraction images are required to get 4 nm resolution.
关键词： Single Particle Imaging,Three-dimensional Reconstruction,X-ray Free Electron Laser,space resolution
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - CAOL 2019 Cover Page
摘要： With the steadily increasing spatial resolution of synthetic aperture radar images, the need for a consistent but locally adaptive image enhancement rises considerably. Numerous studies already showed that adaptive multilooking, able to adjust the degree of smoothing locally to the size of the targets, is superior to uniform multilooking. This study introduces a novel approach of multiscale and multidirectional multilooking based on intensity images exclusively but applicable to an arbitrary number of image layers. A set of 2-D circular and elliptical ?lter kernels in different scales and orientations (named Schmittlets) is derived from hyperbolic functions. The original intensity image is transformed into the Schmittlet coef?cient domain where each coef?cient measures the existence of Schmittlet-like structures in the image. By estimating their signi?cance via the perturbation-based noise model, the best-?tting Schmittlets are selected for image reconstruction. On the one hand, the index image indicating the locally best-?tting Schmittlets is utilized to consistently enhance further image layers, e.g., multipolarized, multitemporal, or multifrequency layers, and on the other hand, it provides an optimal description of spatial patterns valuable for further image analysis. The ?nal validation proves the advantages of the Schmittlets over six contemporary speckle reduction techniques in six different categories (preservation of the mean intensity, equivalent number of looks, and preservation of edges and local curvature both in strength and in direction) by the help of four test sites on three resolution levels. The additional value of the Schmittlet index layer for automated image interpretation, although obvious, still is subject to further studies.
关键词： image analysis,image reconstruction,image representations,image edge analysis,digital ?lters,Adaptive ?lters,image enhancement,synthetic aperture radar (SAR)
更新于2025-09-19 17:13:59
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A Phase Calibration Method for Millimeter-Wave Up-Converter Using Electro-Optic Sampling
摘要： With the steadily increasing spatial resolution of synthetic aperture radar images, the need for a consistent but locally adaptive image enhancement rises considerably. Numerous studies already showed that adaptive multilooking, able to adjust the degree of smoothing locally to the size of the targets, is superior to uniform multilooking. This study introduces a novel approach of multiscale and multidirectional multilooking based on intensity images exclusively but applicable to an arbitrary number of image layers. A set of 2-D circular and elliptical filter kernels in different scales and orientations (named Schmittlets) is derived from hyperbolic functions. The original intensity image is transformed into the Schmittlet coefficient domain where each coefficient measures the existence of Schmittlet-like structures in the image. By estimating their significance via the perturbation-based noise model, the best-fitting Schmittlets are selected for image reconstruction. On the one hand, the index image indicating the locally best-fitting Schmittlets is utilized to consistently enhance further image layers, e.g., multipolarized, multitemporal, or multifrequency layers, and on the other hand, it provides an optimal description of spatial patterns valuable for further image analysis. The final validation proves the advantages of the Schmittlets over six contemporary speckle reduction techniques in six different categories (preservation of the mean intensity, equivalent number of looks, and preservation of edges and local curvature both in strength and in direction) by the help of four test sites on three resolution levels. The additional value of the Schmittlet index layer for automated image interpretation, although obvious, still is subject to further studies.
关键词： Adaptive filters,digital filters,image analysis,image reconstruction,image representations,image edge analysis,image enhancement,synthetic aperture radar (SAR)
更新于2025-09-19 17:13:59
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Real-Time 3D Reconstruction of Thin Surface Based on Laser Line Scanner
摘要： The truncated signed distance field (TSDF) has been applied as a fast, accurate, and flexible geometric fusion method in 3D reconstruction of industrial products based on a hand-held laser line scanner. However, this method has some problems for the surface reconstruction of thin products. The surface mesh will collapse to the interior of the model, resulting in some topological errors, such as overlap, intersections, or gaps. Meanwhile, the existing TSDF method ensures real-time performance through significant graphics processing unit (GPU) memory usage, which limits the scale of reconstruction scene. In this work, we propose three improvements to the existing TSDF methods, including: (i) a thin surface attribution judgment method in real-time processing that solves the problem of interference between the opposite sides of the thin surface; we distinguish measurements originating from different parts of a thin surface by the angle between the surface normal and the observation line of sight; (ii) a post-processing method to automatically detect and repair the topological errors in some areas where misjudgment of thin-surface attribution may occur; (iii) a framework that integrates the central processing unit (CPU) and GPU resources to implement our 3D reconstruction approach, which ensures real-time performance and reduces GPU memory usage. The proposed results show that this method can provide more accurate 3D reconstruction of a thin surface, which is similar to the state-of-the-art laser line scanners with 0.02 mm accuracy. In terms of performance, the algorithm can guarantee a frame rate of more than 60 frames per second (FPS) with the GPU memory footprint under 500 MB. In total, the proposed method can achieve a real-time and high-precision 3D reconstruction of a thin surface.
关键词： parallel computing,laser line scanner,thin surface,GPU,real-time 3D reconstruction
更新于2025-09-19 17:13:59
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Real‐Time Three‐Dimensional Imaging of Dielectric Bodies Using Microwave/Millimeter‐Wave Holography || Microwave/Millimeter Wave Holography Based on the Concepts of Optical Holography
摘要： Holographic imaging was first introduced in the field of optics in the late forties, when Gabor aimed at improving the quality of the images in electron microscopy. He proposed an approach to capture the magnitude and phase of a wave by means of an interference pattern formed by that wave and a known reference wave. He also developed the mathematical approach to the image reconstruction from such interference patterns. Later, in the early sixties, Leith and Upatnieks improved Gabor’s experimental setup. In their method, the reference wave is a distinct beam separated from the illuminating beam by using a beam splitter. The reference beam travels at a substantial angle to the illuminating beam and is so inclined as to never illuminate the object. This new method of providing the reference wave led to separation of the overlapping images originally produced in Gabor’s experimental setup in which the reference and object waves were nearly parallel. As a result of the work of Leith and Upatnieks, higher quality images were obtained. Since then the holography method has significantly influenced optics. In general, since optical recording media such as photographic films only respond to intensity, optical holography is applied as an indirect means of capturing the phase information of the optical wave fronts. It is implemented in two steps. The first step is the hologram formation step and the second step is the wave front reconstruction step.
关键词： optical holography,microwave holography,holography,wave front reconstruction,millimeter wave holography
更新于2025-09-19 17:13:59
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[IEEE 2019 Chinese Automation Congress (CAC) - Hangzhou, China (2019.11.22-2019.11.24)] 2019 Chinese Automation Congress (CAC) - Fixed-time Nonsingular Terminal Sliding Mode Control for MPPT in Stand-alone Photovoltaic Systems
摘要： In preoperative planning for mandibular reconstructive surgery, it is necessary to determine the osteotomy lines for fibular shaping and the proper placement of fibular segments in the mandible. Although virtual surgical planning has been utilized in preoperative decision making, current software designs require manual operation and a trial-and-error process to refine the reconstruction plan. We have developed volumetric fibular transfer simulation software that can quickly design a preoperative plan based on direct volume manipulation and quantitative comparison with the patient’s original mandible. We propose three quantitative shape indicators—volume ratio, contour error, and maximum projection—for symmetrical lesions of the mandible, and have implemented a parallel computation algorithm for the semiautomatic placement of fibular segments. Using this virtual planning software, we conducted a retrospective study of the computed tomography data from nine patients. We found that combining direct volume manipulation with real-time local search of placement improved the applicability of the planning system to optimize mandibular reconstruction.
关键词： Fibular transfer,surgical planning,shape indicator and volume manipulation,mandibular reconstruction
更新于2025-09-19 17:13:59