- 标题
- 摘要
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- 实验方案
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[IEEE 2018 China International SAR Symposium (CISS) - Shanghai (2018.10.10-2018.10.12)] 2018 China International SAR Symposium (CISS) - Coherent Scattering and PolinSAR Imaging Simulation of Fractal Trees
摘要： A 3-D deterministic spatial structure of forest was built and used to calculate the coherent electromagnetic scattering. The trees were generated based on the rule-based growth algorithm. The trunks, branches and leaves in the trees were simplified as a cluster of cylinders and disks, in which every scatterer has its deterministic location and orientation. The generalized Rayleigh-Gans (GRG) approximation and the infinite cylinder approximation are used to calculate the scattering matrix of cylinders and disks. A scatterer above a dielectric plane mainly contributes four scattering components, and the scattering of each component was added coherently. The effects of attenuation and phase change in each component were taking into account using Foldy’s approximation. The scattering coefficient of one tree and a forest were both calculated, which was used to simulate PolinSAR images.
关键词： fractal tree,vegetation scattering simulation,coherent scattering,multi-ray approach
更新于2025-09-23 15:22:29
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Modeling of circular fractal antenna using BFO-PSO-based selective ANN ensemble
摘要： Accurate design of miniaturized antenna is constrained by the limited well‐formulated exact mathematical expressions. Demands for smart devices with features like portability, implantability, and configurability have further placed bigger challenges in front of the antenna design engineers or scientists. As a part of the search for various solutions, many innovative approaches have been proposed by various authors in different literatures. Application of soft computing is also another design approach to accurate design of fractal antenna. Here, the authors have attempted to propose a better solution to miniaturized antenna and its design. A fractal antenna based on circular outer geometry has been proposed as a solution to the search of miniaturized antennas, and a particle swarm optimization–based selective artificial neural networks ensemble is developed, which is employed as the objective function of a bacterial foraging optimization algorithm leading to a hybridized algorithm. The developed hybrid algorithm is utilized to develop the proposed antenna at 2.45 GHz. A good agreement of the simulated, desired, and experimental results validates the proposed design approach.
关键词： BFO,ANN ensemble,ISM band,fractal antenna,PSO
更新于2025-09-23 15:22:29
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[IEEE 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Odessa, Ukraine (2018.9.4-2018.9.7)] 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - The Quasi-Fractal Microstrip Antenna
摘要： The results of study of integral characteristics of quasi-fractal circular-patch monopole antennas are presented. They are obtained by using the Finite Element Method (FEM). The spectral characteristics, matching characteristics with external circuits, the pattern characteristics are presented. The results obtained show that quasi-fractal monopole microstrip resonators can be successfully used to provide the necessary integral parameters and to form the required parameters of radiated fields.
关键词： fractal,disk monopole,pattern characteristic,microstrip,spectrum
更新于2025-09-23 15:21:21
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Sierpi??ski Fractals as Plasmonic Metastructures for Second-Harmonic Generation
摘要： Metallic Sierpiński fractal metastructures made of gold nanoprisms that exhibit compatibility for both surface-enhanced Raman spectroscopy and second-harmonic generation have been prepared by electron-beam lithography. A sequential series of Sierpiński patterns were investigated up to the eighth-order generation. The presence of localized surface plasmon modes in the visible spectral range is due to the arrangement of the individual triangles forming the Sierpiński geometry, and was first exploited for surface-enhanced Raman measurements after functionalization of the plasmonic platform with p-Nitrothiophenol. Due to the non-centrosymmetric arrangement of the individual nanoprisms within the Sierpiński pattern, second-harmonic generation (SHG) microscopy measurements were conducted to evaluate the second-order nonlinear optical activity and its relationship to the spatial distributions of electromagnetic enhancement over the surface of the metastructure. Functionalization of the surface with molecules with an electron withdrawing group appears to further enhance the surface SHG signal.
关键词： Metamaterials,Plasmonics,Fractal plasmonics,Surface-enhanced Raman,Second-harmonic generation
更新于2025-09-23 15:21:01
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Semiclassical theory of laser-assisted radiative recombination
摘要： We study the process of laser-assisted radiative recombination of an electron with a proton by using a semiclassical approach involving calculation of classical trajectories in combined laser and Coulomb fields. Due to chaotic scattering in the combined fields, the radiation probability as a function of the impact parameter and the constant phase of the laser field exhibits chaotic behavior and fractal structures. We obtain a strong enhancement of the recombination cross section as compared to the laser-free case due to the Coulomb focusing effect. For sufficiently low incident electron velocities the cross section becomes infinite, and we limit it by assuming a finite laser pulse duration. With the pulse duration tp = 5 ps we obtain the gain factor for capture into the ground state of the hydrogen atom of about 220 for infrared fields in the intensity range 109–1012 W/cm2. The gain factor grows with tp but slower than linearly.
关键词： chaotic scattering,fractal structures,semiclassical approach,Coulomb focusing effect,laser-assisted radiative recombination
更新于2025-09-23 15:21:01
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[Lecture Notes in Electrical Engineering] Microelectronics, Electromagnetics and Telecommunications Volume 521 (Proceedings of the Fourth ICMEET 2018) || Wide Band Sierpinski Carpet Rectangular Microstrip Fractal Antenna Using Inset-Fed for 5G Applications
摘要： The objective of this paper is to propose a wide band Sierpinski carpet rectangular microstrip fractal antenna fed with inset-fed for 5G applications. This proposed antenna design consists of the third iteration of Sierpinski carpet fractal on the rectangular patch and partial ground structure print on both sides of FR4 epoxy material with a dielectric constant of 4.4 and 0.4 mm thickness at 28 GHz. The simulated result shows a wide impedance bandwidth of 9.16 GHz and 8.43 dB gain. It can further be con?gured to an array of fractals for high gain and bandwidth, frequency selective surface (FSS), and radar applications.
关键词： Inset-fed and partial ground,Fractal antenna,Wide band,Sierpinski carpet
更新于2025-09-23 15:21:01
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Topographic characterization of zirconia-based ceramics by atomic force microscopy: A case study on different laser irradiations
摘要： The purpose of the present study is to evaluate the effects of different laser irradiations including Nd-YAG (neodymium-doped yttrium aluminum garnet laser; Nd:Y3Al5O12), Er-YAG (erbium-doped yttrium aluminum garnet laser, erbium YAG laser), and Carbon dioxide (CO2) infrared lasers on surface topography of zirconia-based ceramics samples which were prepared by copy milling technique. Three dimensional (3D) atomic force microscopy (AFM) images were applied to investigate surface properties by extracting information via MountainsMap? Premium software which divides the surface into peaks and pits and through watershed segmentation algorithm. This method made motif analysis possible by detecting surface dimensions, curvature, volume, perimeters, shape, structure, etc.
关键词： Atomic force microscopy,Laser irradiation,Stereometric analysis,Fractal analysis
更新于2025-09-23 15:21:01
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Etching-controlled preparation of large-area fractal graphene by low-pressure CVD on polycrystalline Cu substrate
摘要： Fractal graphene can provide more active sites for electrocatalytic reactions due to its unique morphology. The preparation of large-area fractal graphene and the understanding of its morphology evolution are crucial to the improvement of catalytic performance. Chemical vapour deposition (CVD) technology is a unique method to obtain high quality fractal graphene. In this study, low-pressure CVD method was used to prepare fractal graphene on Cu substrate. Through the etching effect of hydrogen in the cooling process, the evolution process of graphene from compact to dentritic was realized and the fractal dimensions of graphene with different morphologies were calculated. It was found that the hydrogen etching reaction of graphene begins at the edges and moves towards the nucleation point gradually until the etching progress is completed. And continuous large-area fractal graphene films were obtained for the first time, which would find potential application in electrocatalysis and other fields.
关键词： Fractal graphene,Etching,Chemical vapour deposition
更新于2025-09-23 15:21:01
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[IEEE 2018 IEEE Workshop on Complexity in Engineering (COMPENG) - Florence, Italy (2018.10.10-2018.10.12)] 2018 IEEE Workshop on Complexity in Engineering (COMPENG) - Fractal-Radiomics as Complexity Analysis of CT and MRI Cancer Images
摘要： Cancer is the second leading cause of death globally. Early diagnosis can allow intervention to reduce mortality but due to cancer complex structure and spatial heterogeneity among different tumors and within each lesion, it is difficult to differentiate it from healthy tissue using conventional imaging techniques. Quantification of its complexity can be a prognostic tool for fighting this disease. In recent years, clinical imaging allows this quantification thanks to Radiomics, which extracts features from images. In this study, Fractal Dimension (FD) and Lacunarity (L) in computed tomography (CT) and magnetic resonance (MR) images for different kinds of cancer were examined using box counting method. Our aim is to highlight the potentiality of features based on fractal analysis, in order to obtain new indicators able to detect tumor spatial complexity and heterogeneity. The results indicated that both FD and L show problems linked to the lack of connection between complexity estimated with Radiomics and the underlying biological model.
关键词： cancer heterogeneity,lacunarity,complexity,fractal analysis,cancer,Radiomics
更新于2025-09-23 15:21:01
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[Lecture Notes in Electrical Engineering] Microelectronics, Electromagnetics and Telecommunications Volume 521 (Proceedings of the Fourth ICMEET 2018) || Bandwidth Enhancement of Circular Ring Fractal Antenna for Wireless Applications
摘要： A pentaband direct fed circular patch antenna with ring fractals is proposed in this paper. The design and analysis of proposed antenna are done by using Ansoft HFSS. To enhance the bandwidth of patch antenna, fractals are implemented. The proposed antenna is designed to four iterations on the circular patch, which covers WLANs and WiMAX applications. The impedance bandwidths achieved are 390 MHz, 330 MHz, 190 MHz, 380 MHz, and 860 MHz at the resonant frequencies 1.68 GHz, 2.49 GHz, 2.73 GHz, 3.94 GHz, and 5.65 GHz, respectively. The corresponding peak gains at their resonant frequencies are 2.789 dB, 3.574 dB, 4.658 dB, 3.427 dB, and 4.803 dB respectively. The designed antenna is used for S-band and C-band applications.
关键词： Ring fractal,Circular patch,Multiband
更新于2025-09-23 15:21:01