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Search Results: 1 - 10 of 146958 matches for " WANG Yi-Ding "
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Doped cap layer effect on impurity-free vacancy enhanced disordering in InGaAs/InP quantum well structures
Yu-Peng An,Yi-Ding Wang,Feng Cao
Optica Applicata , 2010,
Abstract: Strong influence on impurity-free vacancy enhanced disordering by the cap layer doping is studied on the InGaAs/InP quantum well structure with a doped cap layer. The observations are consistent with intermixing experiments using both Si3N4 and SiO2 as encapsulation dielectric layers. The largest intermixing occurs in the n-InP capped samples and is explained by the enhancement in out-diffusion of positive ions by the built-in electric field.
Ionospheric Effects on Linear FM Rectangular Envelope Signals
电离层对星载SAR矩形包络线性调频信号的影响

FENG Yue,HONG Jun,WANG Yi-ding,
冯越
,洪峻,王一丁

遥感学报 , 2004,
Abstract: Ionospheric effects on linear FM rectangular envelope signals of space-borne SAR are considered in this paper. Two kinds of effects due to the ionosphere are presented and the relative formulas are derived, including compressed pulse shift and second phase error. It can be seen that the compressed pulse shift is proportional to total electron content (TEC) and inverse proportional to the square of signals frequencies,and that the second phase error is proportional to TEC and the square of signals bandwidth while in inverse proportional to the square of signals frequencies at the same time. The ionospheric effects at P, L, C bands are also investigated by comparison based on the formulas derived above. The result shows that signals at P-band will be severely affected by the ionosphere. The effects will be obvious at L-band if the signals have a large bandwidth or TEC values are high. At C-band, ionospheric effects are neglectable.
Development of λ~3μm Short-wavelength Mid-infrared Quantum Cascade Lasers
λ~3μm短波长中红外量子级联激光器的发展及最新研究成果

SHI Jing-bo WANG Yi-ding,
石泾波
,王一丁

红外 , 2008,
Abstract: A Quantum Cascade Laser(QCL)is a new monopolar source based on intersubband elec- tronic transitions.With the development of the quantum cascade technique,it is particularly important to develop short wave quantum cascade lasers.In this paper,the new operation principle,design ideas and features of the short wave quantum cascade lasers developed recently are presented in brief,the cur- rent status of the short wave quantum cascade laser research is summerized and its future development is forecasted.
GPS observations of TID events generated by the moving solar terminator
与日夜交替线移动相关的中尺度电离层扰动GPS网观测

WANG Min,DING Feng,WAN Wei-Xing,NING Bai-Qi,CHEN Yi-Ding,
王敏

地球物理学报 , 2009,
Abstract: 本文选取由国际GPS服务中心(IGS)提供的北美中纬度地区GPS网TEC观测数据,通过多通道最大熵频谱分析方法研究了2005年(太阳活动低年)地磁活动平静期间日出和日落时由于日夜交替线的移动而激发的中尺度电离层扰动(MSTID),并统计分析其季节变化特性.结果表明:(1)日出或日落期间,在中纬度地区经常观测到由日夜交替线移动激发的中尺度电离层扰动.扰动主要沿日夜交替线运动方向传播,平均持续时间约2~3 h;振幅在0.2~0.8 TECU之间,水平波长,水平相速度和周期分别为300±150 km,150±80 m/s和25±15 min;(2)由日夜交替线移动激发的中尺度电离层扰动在春秋分出现率较少;在夏季,扰动在黄昏时出现率达最大值,在日出后少量出现;而冬季则日出后的扰动效应更为明显.分析表明,在中纬地区,这种扰动出现率随季节的变化与不同季节的日出日落时刻太阳EUV辐射通量变化过程的快慢,以及电离层中离子损失过程快慢有关.
Clutter Rejection Method in SAR Radiometric Calibration
SAR辐射定标中的地物杂波抑制方法

WANG Yi-ding,TU Guo-fang,HONG Jun,
王一丁
,涂国防,洪峻

遥感学报 , 2005,
Abstract: SAR radiometric calibration accuracy is influenced by background clutter. In order to obtain high radiometric calibration accuracy, certain signal and clutter ratio (SCR) requirement must be satisfied or the SCR should be increased by clutter rejection method. This paper studies Active Coded Radiometric Calibration Technique (ACRCT) of SAR and a clutter rejection method based on azimuth signal phase shifter coding and presents the inversion of rang signal frequency modulation. We adopted Range-Doppler imaging algorithm to simulate reference point target and distributed clutter. We also studied SAR radiometric calibration accuracy by peak value method. Experiment results prove that ACRCT could effectively restrain the influence of background clutter signal and improve the precision of radiometric calibration of SAR.
Application of Apodization Method in SAR/ISAR Processing
变量切趾技术在SAR/ISAR图像处理中的应用

Wang Yi-ding,Ji Hui-bo,Hong Jun,
王一丁
,纪慧波,洪峻

电子与信息学报 , 2003,
Abstract: SAR/ISAR image processing involves a 2D Fourier transform that produce high intensity sidelobes which obscure low intensity scatters in the image. Although sidelobes can be reduced using parametric windows, the image resolution becomes worse. Apodization technique can reduce sidelobe levels while maintaining the image resolution. In this paper, based on the analysis of apodization algorithm, a modified apodization method is presented via stronger constraint. The modified method has higher resolution and lower sidelobe levels than the original method. The correctness of this method is proved by using a real ISAR image.
An Object Image Recognition Method Based on the Color Information of A High Temperature Radiator
基于高温辐射体颜色信息的目标图像识别方法

PENG Xiao-qi,SUN Yuan,WANG Yi-ding,
彭小奇
,孙元,王一丁

中国图象图形学报 , 2008,
Abstract: 鉴于准确识别待测目标是利用CCD图像传感器进行高温测量的关键,为此在对高温辐射体彩色图像的噪声特点进行分析的基础上,提出了一种基于高温辐射体颜色信息的目标图像识别方法。该方法首先通过对红、绿基色图像分别进行分割来减小甚至消除高温辐射体图像的各种噪声;然后综合红、绿基色图像的分割结果实现高温辐射体的准确识别,并运用数学形态学方法对分割结果进行后处理,以消除游离点和孔洞,使图像边缘平滑。实验结果表明,该方法可以有效地实现高温辐射体的正确识别,具有较强的实用性。
Algorithm Based on Sliding Window for Similarity Queries over Data Stream
一种基于滑动窗口的数据流相似性查询算法

WANG Kao-jie,ZHENG Xue-feng,Song Yi-ding,
王考杰
,郑雪峰,宋一丁

计算机科学 , 2010,
Abstract: Similarity queries are fundamental part of modern data mining application. But traditional ctuery algorithms can not be applied on data stream, which is an unbounded sectuence of data elements generated at a rapid rate. We proposed a novel approach for computing similarity over multi data streams based on wavclet sliding window model. The basic idea is to divide sliding window into equally-sized basic windows and represent the data elements of a basic window using wavelet coefficients, then form wavelet synopses window. As a result, queries toward data streams can be converted to queries toward such wavelet synopses. This algorithm takes advantage of the merit of wavelet decomposition for linear computing and achieves superior runtime performance. The extensive experiments verified the effectiveness of our algorithm.
Effects of Biochar on Soil Microbial Biomass after Four Years of Consecutive Application in the North China Plain
Qing-zhong Zhang, Feike A. Dijkstra, Xing-ren Liu, Yi-ding Wang, Jian Huang, Ning Lu
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0102062
Abstract: The long term effect of biochar application on soil microbial biomass is not well understood. We measured soil microbial biomass carbon (MBC) and nitrogen (MBN) in a field experiment during a winter wheat growing season after four consecutive years of no (CK), 4.5 (B4.5) and 9.0 t biochar ha?1 yr?1 (B9.0) applied. For comparison, a treatment with wheat straw residue incorporation (SR) was also included. Results showed that biochar application increased soil MBC significantly compared to the CK treatment, and that the effect size increased with biochar application rate. The B9.0 treatment showed the same effect on MBC as the SR treatment. Treatments effects on soil MBN were less strong than for MBC. The microbial biomass C:N ratio was significantly increased by biochar. Biochar might decrease the fraction of biomass N mineralized (KN), which would make the soil MBN for biochar treatments underestimated, and microbial biomass C:N ratios overestimated. Seasonal fluctuation in MBC was less for biochar amended soils than for CK and SR treatments, suggesting that biochar induced a less extreme environment for microorganisms throughout the season. There was a significant positive correlation between MBC and soil water content (SWC), but there was no significant correlation between MBC and soil temperature. Biochar amendments may therefore reduce temporal variability in environmental conditions for microbial growth in this system thereby reducing temporal fluctuations in C and N dynamics.
ANALYSIS AND DESIGN OF RBF NEURAL NET BASED ON INFORMATION DIFFUSION
基于信息扩散原理的RBF网络的分析与设计

Wang Yun-hong,LIU Guo-sui,WANG Yi-ding,
王蕴红
,刘国岁,王一丁

红外与毫米波学报 , 1998,
Abstract: 从信息扩散的角度对RBF网络进行了分析,从理论上证明了RBF网络具有信息扩散功能,并分析了其网络的物理意义。说明了根据正态扩散的择近原则确定RBF网络中规划因子的合理性,也说明了在训练样本数目大时用聚类方法确定中心参数的优越性。
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