- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Phase Retrieval of Real-valued Functions in Sobolev Space
摘要： The Sobolev space H s(Rd) with s > d/2 contains many important functions such as the bandlimited or rational ones. In this paper we propose a sequence of measurement functions { (cid:2)φγ j,k} ? H ?s(Rd) to the phase retrieval problem for the real-valued functions in H s(Rd). We prove that any real-valued function f ∈ H s(Rd) can be determined, up to a global sign, by the phaseless measurements {|(cid:4)f, (cid:2)φγ j,k(cid:5)|}. It is known that phase retrieval is unstable in in?nite dimensional spaces with respect to perturbations of the measurement functions. We examine a special type of perturbations that ensures the stability for the phase-retrieval problem for all the real-valued functions in H s(Rd) ∩ C 1(Rd), and prove that our iterated reconstruction procedure guarantees uniform convergence for any function f ∈ H s(Rd) ∩ C 1(Rd) whose Fourier transform (cid:3)f is L1-integrable. Moreover, numerical simulations are conducted to test the e?ciency of the reconstruction algorithm.
关键词： measurement function perturbation,phase retrieval,retrievable stability,reconstruction stability,Sobolev space
更新于2025-09-23 15:21:01
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Prior-Guided Metal Artifact Reduction for Iterative X-Ray Computed Tomography
摘要： High-attenuation materials pose significant challenges to computed tomographic (CT) imaging. Formed of high mass-density and high atomic number elements, they cause more severe beam hardening and scattering artifacts than do water-like materials. Pre-corrected line-integral density measurements are no longer linearly proportional to the path lengths, leading to reconstructed image suffering from streaking artifacts extending from metal, often along highest-density directions. In this paper, a novel prior-based iterative approach is proposed to reduce metal artifacts. It combines the superiority of statistical methods with the benefits of sinogram completion methods to estimate and correct metal-induced biases. Preliminary results show minimized residual artifacts and significantly improved image quality.
关键词： statistical reconstruction,metal artifact reduction,beam hardening correction,computed tomography,iterative reconstruction
更新于2025-09-23 15:19:57
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Digital Modeling and Display of Ancient Architecture Based on Multi-Station Laser Scanning
摘要： In order to better display and protect ancient Chinese architecture, a three-dimensional model reconstruction method based on multi-station laser scanning is proposed. This method mainly includes several steps, such as point cloud data collection, preconditioning, multi-site cloud data fusion, point cloud data compression, 3D model reconstruction and texture mapping, environment rendering, video processing, and 3D roaming. According to the requirement of video rendering and virtual roaming, we focus on cloud processing, 3D modeling and 3D model display in this paper. Experimental results show that an famous building named Enshi Dong Drum Tower is well digitally reconstructed, so as to result in ethnic characteristics and cultural heritage protection in practical application.
关键词： 3D laser scanning,3D reconstruction,ancient architecture,point cloud data,digital modeling
更新于2025-09-23 15:19:57
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[IEEE 2019 4th International Conference on Mechanical, Control and Computer Engineering (ICMCCE) - Hohhot, China (2019.10.24-2019.10.26)] 2019 4th International Conference on Mechanical, Control and Computer Engineering (ICMCCE) - Design of a Stroboscopic Laser Grating Stripe Projection Device
摘要： A three-dimensional measuring system based on a line-structured laser and a high-speed rotating multi-faced prism has been designed and described in detail. The grating fringe can be produced using stroboscopic effect the system. The relationship between grating stripe and modulation signal and prism rotation speed are analyzed from both theoretical and experimental aspects. At the same time, the grating stripe projection device is applied to the three-dimensional measurement of gypsum section.
关键词： grating fringe,stroboscopic effect,laser,three-dimensional reconstruction
更新于2025-09-23 15:19:57
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Effective Fixation of Carbon in ga??C <sub/>3</sub> N <sub/>4</sub> Enabled by Mga??Induced Selective Reconstruction
摘要： The methodology of metal-involved preparation for carbon materials is favored by researchers and has attracted tremendous attention. Decoupling this process and the underlying mechanism in detail are highly required. Herein, the intrinsic mechanism of carbon fixation in graphitic carbon nitride (g-C3N4) via the magnesium-involved carbonization process is reported and clarified. Magnesium can induce the displacement reaction with the small carbon nitride molecule generated by the pyrolysis of g-C3N4, thus efficiently fixing the carbon onto the in situ template of Mg3N2 product to avoid the direct volatilization. As a result, the N-doped carbon nanosheet frameworks with interconnected porous structure and suitable N content are constructed by reconstruction of carbon and nitrogen species, which exhibit a comparable photoelectric conversion efficiency (8.59%) and electrocatalytic performances to that of Pt (8.40%) for dye-sensitized solar cells.
关键词： magnesium inducement,reconstruction mechanism,dye-sensitized solar cells,graphitic carbon nitride (g-C3N4),tri-iodide reduction
更新于2025-09-23 15:19:57
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Elliptical fibre dielectric waveguides: a transverse transmission line analysis
摘要： Non-rigid structure-from-motion (NRSfM) is the process of recovering time-varying 3D structures and poses of a deformable object from an uncalibrated monocular video sequence. Currently, most NRSfM algorithms utilize a non-degenerate assumption for non-rigid object deformations whereby the 3D structures of a non-rigid object can be assumed to be a linear combination of basis shapes with full rank three. Unfortunately, this assumption will produce extra degrees-of-freedom when the non-rigid object has some degenerate deformations with shape bases of rank less than three. These extra degrees-of-freedom will yield spurious shape deformations due to non-negligible noise in real applications, which will cause substantial reconstruction errors. To solve this problem, we propose a low-rank shape deformation model to represent 3D structures of degenerate deformations. When modeling degenerate deformations, the proposed model exploits the rank-deficient nature of degenerate deformations in addition to the low-rank property of non-rigid objects’ trajectories, thus providing a more accurate and compact representation compared with existing models. Based on this model, we formulate the NRSfM problem as two coherent optimization problems. These problems are solved with iterative non-linear optimization algorithms. Experiments on synthetic and motion capture data are conducted. The results exhibit the significant advantages of our approach over state-of-the-art NRSfM algorithms for the 3D recovery of non-rigid objects with degenerate deformations.
关键词： 3D reconstruction.,Degenerate deformations,non-rigid structure from motion,low-rank shape deformation model
更新于2025-09-23 15:19:57
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Mode-locked Tm Fiber Laser with a tapered GIMF SA based on Nonlinear Multimode Interference effect
摘要： Optimal frames have been used in signal processing to minimize the reconstruction errors when erasures occurred during the frame coefficient transmission, and much of the recent work has been focused either on characterizations or on the constructions of optimal frames (or dual frames) prior to signal encoding. In this paper, we propose a new approach, based on the method of optimal directions, which can search adaptively optimal dual frames in the process of signal reconstruction. We provide concrete algorithms for constructing adaptive optimal dual frames and the reconstruction of signals. In addition, several numerical experiments are presented to demonstrate the efficiency and comparison of the new method with the existed methods.
关键词： Erasures,frames,Hilbert spaces,optimal dual frames,reconstruction
更新于2025-09-23 15:19:57
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Automatic Process Parameters Tuning and Surface Roughness Estimation for Laser Cleaning
摘要： Non-rigid structure-from-motion (NRSfM) is the process of recovering time-varying 3D structures and poses of a deformable object from an uncalibrated monocular video sequence. Currently, most NRSfM algorithms utilize a non-degenerate assumption for non-rigid object deformations whereby the 3D structures of a non-rigid object can be assumed to be a linear combination of basis shapes with full rank three. Unfortunately, this assumption will produce extra degrees-of-freedom when the non-rigid object has some degenerate deformations with shape bases of rank less than three. These extra degrees-of-freedom will yield spurious shape deformations due to non-negligible noise in real applications, which will cause substantial reconstruction errors. To solve this problem, we propose a low-rank shape deformation model to represent 3D structures of degenerate deformations. When modeling degenerate deformations, the proposed model exploits the rank-deficient nature of degenerate deformations in addition to the low-rank property of non-rigid objects’ trajectories, thus providing a more accurate and compact representation compared with existing models. Based on this model, we formulate the NRSfM problem as two coherent optimization problems. These problems are solved with iterative non-linear optimization algorithms. Experiments on synthetic and motion capture data are conducted. The results exhibit the significant advantages of our approach over state-of-the-art NRSfM algorithms for the 3D recovery of non-rigid objects with degenerate deformations.
关键词： Degenerate deformations,non-rigid structure from motion,3D reconstruction,low-rank shape deformation model
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC) - Macao, Macao (2019.12.1-2019.12.4)] 2019 IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC) - A Single-Stage Flyback LED Driver Based On Energy Distribution Without Electrolytic Capacitor
摘要： The lp (0 < p < 1) regularization has attracted a great attention in the compressive sensing field, because it can obtain sparser solutions than the well-known l1 regularization. Recently, we developed an approximate general analytic thresholding representation for any lp regularization with 0 < p < 1. The derived thresholding representations are exact for the well-known soft-threshold filtering for l1 regularization and the hard-threshold filtering for l0 regularization. Because the lp regularization is a nonconvex problem, an iterative algorithm can only converge to local optima instead of the global optimum. In this paper, we propose an alternating iteration algorithm for computed tomography reconstruction in a thresholding form based on our general analytic thresholding representation for better convergent properties. The alternating iteration algorithm alternatively minimizes one l1 and one lp (0 < p < 1) regularized objective functions. While the lp regularization can help to find a sparser solution, the l1 regularization can help to monitor the solution not away from the global optimum. Both numerical simulations and phantom experiments are performed to evaluate the proposed alternating iteration algorithm. Compared with the lp (0 < p < 1) regularization using a single p, the proposed alternating iteration algorithm reduces more data measurements for accurate reconstruction and is more robust for projection noise.
关键词： image reconstruction,Compressive sensing,least square solution,computed tomography,alternating iteration,lp regularization
更新于2025-09-23 15:19:57
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[IEEE 2019 Sixteenth International Conference on Wireless and Optical Communication Networks (WOCN) - Bhopal, India (2019.12.19-2019.12.21)] 2019 Sixteenth International Conference on Wireless and Optical Communication Networks (WOCN) - Multiband Slotted Microstrip Patch Antenna with Conducting Strips
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,mandibular reconstruction,shape indicator and volume manipulation,surgical planning
更新于2025-09-23 15:19:57