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This paper addresses the estimation of adjacency effect of CBERS-2 image. The adjacency effect influences the digital number (DN) value of a pixel by adding surrounding scattering signals and path scattering signals. Based on the theory of radiation transfer model, a procedure is designed to measure the reflectance from the surface target materials and the materials in a box, which is 1.5 m above the surface to avoid upwelling reflectance. The results show that the adjacency effect varies from visible, near infrared and becomes steady within short infrared wavelength region; the adjacency effect weakens with the increase of distance between testing sites. The adjacency effect of CBERS-2 image is corrected and the quality of the resulting image is improved. 相似文献
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配备电子冷却装置的重离子储存环为开展高电荷态离子的双电子复合(dielectronic recombination,DR)精密谱学研究提供了绝佳的实验平台。本工作在兰州重离子加速器冷却储存环主环(HIRFL-CSRm)上开展了类锂36,40Ar15+离子的双电子复合实验,实验观测了电子-离子质心系能量范围为0~35 eV的双电子复合速率系数谱。通过外推法获得了36,40Ar15+离子2s1/2→2p1/2和2s1/2→2p3/2的跃迁能量。同时利用GRASP2K程序理论计算了36,40Ar15+离子2s1/2→2p1/2和2s1/2→2p3/2跃迁的质量移动因子和场移动因子,进而得到双电子复合谱的同位素移动值。36,40Ar15+离子2s1/2→2p1/2和2s1/2→2p3/2同位素移动分别为0.861 meV和0.868 meV。它们均小于目前CSRm上双电子复合实验的实验分辨为~10 meV,进而解释了实验测量的DR谱上未能观察到同位素移动的原因。然而,高电荷态离子的同位素移动场效应与原子序数Z5成正比,因此,在重离子加速器冷却储存环实验环(HIRFL-CSRe)以及未来大型加速器--强流重离子加速器装置(HIAF)上有望通过DR精密谱学方法研究高电荷态重离子甚至放射性离子的同位素移动,进而获得相关原子核的核电荷半径等信息。The cooler storage ring is equipped with an electron-cooler. It is an excellent experimental platform for dielectronic recombination (DR) experiment of highly-charged ions. In this paper, the dielectronic recombination experiments of lithium-like Ar15+ ions with mass number 36 and 40 are conducted at the HIRFL-CSRm(main ring of the Cooling Storage Ring of Heavy Ion Research Facility in Lanzhou). The experimental electron-ion collision energy scale is from 0 eV to 35 eV. Extrapolation method is exploited to obtain the excitation energies of transitions 2s1/2→2p1/2 and 2s1/2→2p3/2 of the 36,40Ar15+ ions from experimental data. Meanwhile, GRASP2K program is utilized to calculate the mass shift factors and field shift factors of 36,40Ar15+ ions for 2s1/2→2p1/2 and 2s1/2→2p3/2 transitions to obtain isotope shifts in DR spectra. In theoretical calculation, isotope shifts of 36,40Ar15+ ions corresponding to 2s1/2→2p1/2 and 2s1/2→2p3/2 are 0.861 meV and 0.868 meV, respectively. They are both less than the experimental precision (~10 meV) of these dielectronic recombination experiments at the CSRm, which explains that isotope shifts cannot be distinguished from the experimental dielectronic recombination spectra. However, the field shift of highly-charged ions is proportional to Z5. In the future, the dielectronic recombination experiments of highly-charged heavy ions even radioactive ions will be conducted at the HIRFL-CSRe (experimental ring of the Cooling Storage Ring of Heavy Ion Research Facility in Lanzhou) and the future large accelerator facility--HIAF(High intensity Heavy-ion Accelerator Facility) to measure isotope shifts to obtain the nuclear charge radius information. 相似文献
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An acoustic dipole radiation model for magnetoacoustic tomography with magnetic induction (MAT-MI) is pro-posed,based on the analyses of one-dimensional tissue vibration,three-dimensional acoustic dipole radiation and acoustic waveform detection with a planar piston transducer.The collected waveforms provide information about the conductiv-ity boundaries in various vibration intensities and phases due to the acoustic dipole radiation pattern.Combined with the simplified back projection algorithm,the conductivity configuration of the measured layer in terms of shape and size can be reconstructed with obvious border stripes.The numerical simulation is performed for a two-layer cylindrical phantom model and it is also verified by the experimental results of MAT-MI for a tissue-like sample phantom.The proposed model suggests a potential application of conductivity differentiation and provides a universal basis for the further study of conductivity reconstruction for MAT-MI. 相似文献
38.
Based on the multi-coincidence measurement, the time resolution of three liquid scintillation detectors (BC501A) were determined strictly by solving the coincidence equations, where the influence from electronics estimated by self coincidence measurement as well as the background had been considered. The result of this work agreed well with the result that was deduced from the traditional method, and it will be helpful to analyze the energy resolution of neutron time of flight spectra measured by using such detectors at CIAE (China Institute of Atomic Energy). 相似文献
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Silicon germanium(SiGe) heterojunction bipolar transistor(HBT) on thin silicon-on-insulator(SOI) has recently been demonstrated and integrated into the latest SOI BiCMOS technology.The Early effect of the SOI SiGe HBT is analysed considering vertical and horizontal collector depletion,which is different from that of a bulk counterpart.A new compact formula of the Early voltage is presented and validated by an ISE TCAD simulation.The Early voltage shows a kink with the increase of the reverse base-collector bias.Large differences are observed between SOI devices and their bulk counterparts.The presented Early effect model can be employed for a fast evaluation of the Early voltage and is useful to the design,the simulation and the fabrication of high performance SOI SiGe devices and circuits. 相似文献
40.
The diffusion behaviours of vanadium implanted p- and
n-type 4H-SiC are investigated by using the secondary
ion mass spectrometry (SIMS).
Significant redistribution, especially out-diffusion of vanadium towards the
sample surface is not observed after 1650℃ annealing for both p-
and n-type samples. Atomic force microscopy (AFM) is applied to the
characterization of
surface morphology, indicating the formation of continuous long furrows
running in one direction across the wafer surface after 1650℃
annealing. The surface roughness results from the
evaporation and re-deposition of
Si species on the surface during annealing. The chemical compositions of
sample surface are investigated using x-ray photoelectron spectroscopy (XPS).
The results of C 1s and Si 2p core-level spectra are presented in detail to
demonstrate the evaporation of Si from the wafer and the deposition of SiO2
on the sample surface during annealing. 相似文献