- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Image processing for three defects of topography images by SPM
摘要： Image processing plays an important role in the topography imaging by SPM. Due to the imperfect hardware and the environmental interference, the image defects can be easily found in the topography images. In order to deal with these defects, image processing technology is the most effective and convenient way, so image processing functions are integrated in most kinds of SPM software. In this study, we present image processing methods for three common defects of topography images: background, damage and fringe. According to the characteristics of the topography images and the defects, some algorithms are adopted in the proposed methods, such as B-spline, TV, Criminisi, Flourier transform and so on. The principles, processes and application scopes of the methods were described in detail, and the topography images with typical defects were selected to verify them. The processing results showed the feasibility of the methods, which offer an effective approach to acquire high-quality topography images in a fast, simple and cheap way.
关键词： Background,Damage,Topography image,Fringe,SPM,Image processing
更新于2025-09-23 15:23:52
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - A New SAR Image Simulation Method for Sea-Ship Scene
摘要： Due to the difficulty of sea scene synthetic aperture radar (SAR) trial, SAR image simulation for sea-ship scene is vitally important for the research of sea remote sensing and surveillance. In this paper, a new SAR image simulation method for sea-ship scene is proposed. Firstly, the geometrical models of sea surface and ship target are obtained through sea spectrum and CAD modeling technology respectively. Then the SAR image intensity data of sea surface is calculated by small perturbation method (SPM) and velocity bunching (VB) theory, meanwhile the radar cross section (RCS) data of ship target is computed through physical optics (PO) method. Finally, the SAR image of sea-ship scene is generated by SAR imaging method after transforming image intensity data and RCS data to the same spectrum domain. The simulation result has verified the effectiveness of the proposed method.
关键词： SPM method,sea-ship scene,CAD,PO method,VB theory,simulation of SAR image
更新于2025-09-23 15:21:01
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Hybrid gate dielectrics: a comparative study between polyvinyl alcohol/ $$\hbox {SiO}_{2}$$ SiO 2 nanocomposite and pure polyvinyl alcohol thin-film transistors
摘要： Polyvinyl alcohol (PVA) thin films as polymer gate dielectrics, with and without SiO2 nanoparticles were fabricated using spin-coating. Surface roughness and hydrophilicity of PVA and PVA/SiO2 thin films were studied by contact-angle measurements and atomic force microscopy. The dielectric properties were characterized via capacitance and leakage-current measurements on metal–insulator–metal structures. In order to further investigate the application potential of such materials as a replacement for conventional inorganic dielectrics such as SiO2 in organic thin-film transistors, devices were fabricated based on these polymers using α, ω-dihexylquaterthiophene as an active layer. Performance of the devices was realized by electrical measurements and Kelvin probe force microscopy. All transistors showed hole and electron mobilities in the low-voltage range. PVA/SiO2 films showed larger capacitance, less hydrophilicity, rougher surfaces and considerable leakage currents compared with those with neat PVA. Although integrating nanoparticles modified surface electronic properties and showed a shift in surface potential as observed in Kelvin probe force measurements, it appears that non-polymeric and neat polymeric dielectric materials could still be a privilege to nanocomposite polymeric dielectrics for optoelectronic applications.
关键词： ambipolar thin-film transistor,scanning probe microscopy (SPM),surface chemistry,electrical and structural properties,Polymer dielectrics
更新于2025-09-19 17:15:36
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Nonlinear Fiber Optics || Group-velocity dispersion
摘要： The preceding chapter showed how the combined effects of group-velocity dispersion (GVD) and self-phase modulation (SPM) on optical pulses propagating inside a fiber can be studied by solving a pulse-propagation equation. Before considering the general case, it is instructive to study the effects of GVD alone. This chapter considers the pulse-propagation problem by treating fibers as a linear optical medium. In Section 3.1 we discuss the conditions under which the GVD effects dominate over the nonlinear effects by introducing two length scales associated with GVD and SPM. Dispersion-induced broadening of optical pulses is considered in Section 3.2 for several specific pulse shapes, including Gaussian and 'sech' pulses. The effects of initial frequency chirping are also discussed in this section. Section 3.3 is devoted to the effects of third-order dispersion on pulse broadening. An analytic theory capable of predicting dispersive broadening for pulses of arbitrary shapes is also given in this section. We discuss in Section 3.4 how the GVD can limit the performance of optical communication systems and how the technique of dispersion management can be used to combat such limitations.
关键词： dispersion management,dispersion-induced broadening,sech pulses,Group-velocity dispersion,GVD,optical pulses,third-order dispersion,SPM,Gaussian pulses,self-phase modulation,fiber propagation,frequency chirping
更新于2025-09-12 10:27:22
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Nonlinear Fiber Optics || Self-phase modulation
摘要： The ?rst nonlinear effect that we focus on is the self-phase modulation (SPM), a phenomenon that leads to spectral broadening of optical pulses [1–9]. SPM is the temporal analog of self-focusing of CW beams occurring inside any nonlinear medium with n2 > 0. It was ?rst observed in 1967 in the context of transient self-focusing of optical pulses propagating through a CS2-?lled cell [1]. By 1970, SPM had been observed in solids and glasses by using picosecond pulses. The earliest observation of SPM in optical ?bers was made with a ?ber whose core was ?lled with CS2 liquid [7]. This work led by 1978 to a systematic study of SPM in a silica-core ?ber [9]. This chapter considers SPM as a simple example of the nonlinear effects that can occur inside optical ?bers. Section 4.1 is devoted to the case of pure SPM as it neglects the GVD effects and focuses on spectral changes induced by SPM. The combined effects of GVD and SPM are discussed in Section 4.2 with emphasis on the SPM-induced frequency chirp. Section 4.3 presents two analytic techniques and uses them to solve the NLS equation approximately. Section 4.4 extends the analysis to include the higher-order nonlinear effects such as self-steepening.
关键词： GVD,self-steepening,spectral broadening,optical pulses,frequency chirp,SPM,nonlinear effects,NLS equation,self-phase modulation
更新于2025-09-12 10:27:22
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Land Cover Change Detection Based on Spatial-Temporal Sub-Pixel Evolution Mapping: A Case Study for Urban Expansion
摘要： In the past decades, land cover change detection (LCCD) has been dramatically developed, since it provides corroborative support for policy decision, regulatory actions, and subsequent urban-rural activities. Satellite remote sensing image is the major source of LCCD since it is able to revisit the Earth’s surface regularly and provide time series images for monitoring and space-time analysis. However, there is always a trade-off between spatial scale and temporal scale, i.e., finer spatial resolution image generally has a lower revisit frequency, leading to an observation omission; while higher revisit frequency image usually has a lower spatial resolution, resulting in a deficiency in detecting finer scale change information. In this paper, a spatial-temporal sub-pixel mapping (SSM) algorithm is proposed on the premise that one pair of fine spatial resolution image with low frequency revisit period and coarse spatial resolution with high frequently revisit period are available, and SSM is taken to restore the coarse image to a finer scale thematic map which can be then compared to the fine image, realizing a frequency and detailed LCCD. SSM is an extension of traditional mono-temporal sub-pixel mapping (SPM) algorithm, and is improved by incorporating temporally fine distribution patterns for a more appropriate restoration of coarse image. A study case for urban expansion LCCD were carried out to verify the ability of the proposed algorithm to handle change detection based on one pair of china-made Gaofen-2 image (GF-2) and Landsat-8 image, the result demonstrate that the proposed SSM algorithm outperform the other traditional SPM, achieving both fine temporal resolution and spatial resolution LCCD for further applications.
关键词： Swarm intelligent theory,spatial-temporal sub-pixel mapping (SSM),Land cover change detection (LCCD),sub-pixel mapping (SPM)
更新于2025-09-10 09:29:36
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Interferometric Angular Decorrelation Analysis of 1-D Rough Surface With Pencil Beam Incidence
摘要： Interferometric synthetic aperture radar (InSAR) uses phase difference of radar echoes, either from multiple passes along the same trajectory or from multiple displaced phase centers on a single pass, to generate interferogram. Scattering correlation in the angular dimension is a critical factor determining the quality of InSAR interferogram. It can be modeled with the angular correlation function (ACF). In this letter, the ACF of a 1-D rough surface under incidence of a tapered wave, namely, a pencil beam, is studied numerically for correlation analysis of InSAR. An analytic ACF is ?rst derived based on the ?rst-order small perturbation method. It is then validated statistically by the method of moment of electromagnetic scattering. Analysis of the ACF simulations indicate that the ACF of backscattering from a randomly rough surface exhibits a shape of sinc function, which depends on tapering parameter g, interferometric incidence angles θ1 and θ2. Several numerical simulations of different rough surface spectrums demonstrate that the analytical ACF ?ts well with numerical results as long as g is the larger several correlation lengths l.
关键词： interferometric synthetic aperture radar (InSAR),Angular correlation function (ACF),small perturbation method (SPM),surface roughness
更新于2025-09-09 09:28:46