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A NEURAL NETWORK APPROACH TO BLIND-ESTIMATION OF PN SPREADING SEQUENCE IN LOWER SNR DS/SS SIGNALS

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A NEURAL NETWORK APPROACH TO BLIND-ESTIMATION OF PN SPREADIN...

A tentative study for the prediction of the CME related geomagnetic storm intensity and its transit time

第七届国际信号处理会议

作者： CHANG Tianqi1 LIN Xiaokang1 ZHOU Zhengzhong2.(1. graduate School at Shen zhen tsinghua {2. shenzhen china 518055 2. School of Communication and Information Eng. UEST of china Chengdu china 610054) Email: zhangtianqi@***

In this paper, an approach based on discrete Karhunen-Loeve transformation of the DS/SS signals is proposed to estimate PN sequence in lower SNR DS/SS signals. Characteristics of self-organization

关键词： discrete Karhunen-Loeve transformation neural networks direct sequence spread spectrum (DS/SS) signal and PN sequence

来源： cnki会议评论

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Science china(Technological Sciences) 2005年第6期48卷 648-668页

作者： ZHAO Xinhua1,2.& FENG Xueshang1,3 1. SIGMA Weather Group, Key Laboratory of Space Weather, Center for Space Science and Applied Re-search, Chinese Academy of Sciences, Beijing 100080, china 2. graduate School of the Chinese Academy of Sciences, Beijing 100039, china 3. School of Geophysics and Geoinformation Systems, china university of Geosciences, Beijing 100083, china 1. SIGMA Weather Group Key Laboratory of Space Weather Center for Space Science and Applied Research Chinese Academy of Sciences 100080 Beijing China 2. graduate School of the Chinese Academy of Sciences 100039 Beijing China 3. School of Geophysics and Geoinformation Systems China University of Geosciences 100083 Beijing China

Using 80 CME-ICME events during 1997.1―2.02.9, based on the eruptive source locations of CMEs and solar magnetic field observation at the photosphere, a current sheet magnetic coordinate (CMC) system is established in order to study the propagation of CME and its geoeffectiveness. In context of this coordinate system, the effect of the eruptive source location and the form of heliospheric current sheet (HCS) at the eruptive time of CME on the geomagnetic storm intensity caused by CME and the CME’s transit time at the Earth is investigated in detail. Our preliminary conclusions are: 1) The geomagnetic disturbances caused by CMEs tend to have the so-called “same side-opposite side effect”, i.e. CMEs erupt from the same side of the HCS as the earth would be more likely to arrive at the earth and the geomagnetic disturbances associated with them tend to be of larger magnitude, while CMEs erupting from the opposite side would arrive at the earth with less probability and the corresponding geomagnetic disturbance magnitudes would be relatively weaker. 2. The angular separation between the earth and the HCS affect the corresponding disturbance intensity. That is, when our earth is located near the HCS, adverse space weather events occur most probably. 3) The erupting location of the CME and its nearby form of HCS will also affect its arrival time at the earth. According to these conclusions, in this context of CMC coordinate we arrive at new prediction method for estimating the geomagnetic storm intensity (Dstmin) caused by CMEs and their transit times. The application of the empirical model for 80 CME-ICME events shows that the relative error of Dst is within 30% for 59% events with Dstmin≤?50 nT, while the averaged absolute error of transit time is lower than 10 h for all events.

关键词： coronal mass ejections, current sheet magnetic coordinate system, geomagnetic storm intensity, transit time, prediction method.

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调节阀多测点空化诱导振动敏感性分析

国防科技大学学报 2024年第4期46卷 125-132页

作者：刘秀梅韦建秋龙正李贝贝孙深圳中国矿业大学机电工程学院江苏徐州221116 山东中烟工业有限责任公司山东济南250014

针对调节阀阀体不同测点处对流道内空化敏感性存在差异问题,开展了不同测点处空化诱导振动的差异性研究和空化发展状态敏感程度分析。搭建了调节阀空化振动加速度信号采集试验平台,同步采集了多测点处调节阀空化诱导振动的加速度信号。... 详细信息

针对调节阀阀体不同测点处对流道内空化敏感性存在差异问题,开展了不同测点处空化诱导振动的差异性研究和空化发展状态敏感程度分析。搭建了调节阀空化振动加速度信号采集试验平台,同步采集了多测点处调节阀空化诱导振动的加速度信号。提出了加速度级比率和重心频率两个表征参数,并利用1/3倍频程谱对调节阀空化振动信号频谱进行划分,最终得到对空化发展最敏感的频带和测点位置。结果表明:调节阀阀体同一表面测点振动信号呈现相似性,不同表面测点信号差异性较大,即调节阀振动信号表现为各向异性;空化状态的发展主要引起中心频率10000 Hz以上的频带振动强度增大,适合作为监测调节阀空化状态的特征频带。

关键词：振动调节阀各向异性加速度级比率重心频率 1/3倍频程分析

Formal Verification under Unknown Constraints

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Wuhan university Journal of Natural Sciences 2005年第1期10卷 43-46页

作者： LI Guang-hui 1,2.3 , LI Xiao-wei 2.31. School of Information Engineering, Zhejiang Forestry College, Hangzhou 311300, Zhejiang, china 2. Institute of Computing Technology, Chinese Academy of Sciences, Beijing 100080, china 3. {2. School of the Chinese Academy of Sciences, Beijing 100039, china School of Information Engineering Zhejiang Forestry College Hangzhou 311300 Zhejiang China

We present a formal method of verifying designs with unknown constraints (e.g., black boxes) using Boolean satisfiability (SAT). This method is based on a new encoding scheme of unknown constraints, and solves the corresponding conjunctive normal form (CNF) ***,this method can avoid the potential memory explosion, which the binary decision diagram (BDD) based techniques maybe suffer from, thus it has the capacity of verifying large designs. Experimental results demonstrate the efficiency and feasibility of the proposed method.

关键词： formal verification unknown constraints black box Boolean satisfiability Boolean comparison

LONG TIME ASYMPTOTIC BEHAVIOR OF SOLUTION OF DIFFERENCE SCHEME FOR A SEMILINEAR PARABOLIC EQUATION (Ⅱ)

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Journal of Computational Mathematics 1998年第5期16卷 571-576页

作者： Hui Feng(shenzhen university Normal College, shenzhen 518060, china Laboratorp of Computational Physics, Institute of Applied Physics and Computational Mathematics,P.O.Box 8009, Beijing 100088, china )Long-jnn Shen(Laboratory of Computational Physics, In shenzhen Univ Wormal Coll Shenzhen 518060 Peoples R China Inst Appl Phys & Computat Math Lab Computat Phys Beijing 100088 Peoples R China

In this paper we prove the solution of explicit difference scheme for a semilinear parabolic equation converges to the solution of difference scheme for the relevant nonlinear stationary problem as t→∞. For nonlinear parabolic problem, we obtain the long time asymptotic behavior of its discrete solution which is analogous to that of its continuous solution. For simplicity, we discuss one-dimensional problem.

关键词： Asymptotic behavior Explicit difference scheme Semilinear parabolic equation.

同方期刊数据库

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逆流色谱溶质出峰顺序的预测

色谱 2002年第6期20卷 526-529页

作者：周玉杰陈福明李总成清华大学化工系北京100084 深圳清华大学研究院广东深圳518057

根据逆流色谱保留方程可知,溶质的出峰顺序主要取决于其在互不混溶的两液相间分配系数的大小顺序。以饱和及不饱和脂肪酸乙酯、2.4 二硝基苯胺基脂肪醇和对硝基苯基葡萄糖甙等结构较为简单、极性差别较大的溶质系列为研究对象,应用修正... 详细信息

根据逆流色谱保留方程可知,溶质的出峰顺序主要取决于其在互不混溶的两液相间分配系数的大小顺序。以饱和及不饱和脂肪酸乙酯、2.4 二硝基苯胺基脂肪醇和对硝基苯基葡萄糖甙等结构较为简单、极性差别较大的溶质系列为研究对象,应用修正的通用基团活度系数(UNIFAC)(Dortmund)模型,通过相平衡计算,预测了它们在含水或不含水的溶剂体系中分配系数的变化趋势,并与前人的工作进行了对比。结果表明,由该方法预测出的相似结构溶质分配系数的顺序基本上与实验值相同,其中对饱和脂肪酸乙酯在己烷乙腈(体积比为1∶1)体系中分配系数的预测最好。这种预测方法的建立将对逆流色谱非电解质溶剂体系的选择具有较大的指导意义。

关键词：溶质出峰顺序预测逆流色谱通用基团活度系数分配系数 UNIFAC模型分离

Systematic distortion in cosmic microwave background maps

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Science china(Physics,Mechanics & Astronomy) 2009年第5期52卷 804-808页

作者： LIU Hao 1,3 &LI TiPei 1,2.1Key Laboratory of Particle Astrophysics,Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,china 2.enter for Astrophysics,tsinghua {2.,Beijing 100084,china 3 graduate {2. of Chinese Academy of Sciences,Beijing 100049,china Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China Center for Astrophysics Tsinghua University Beijing 100084 China graduate university of Chinese Academy of Sciences Beijing 100049 China

To minimize instrumentally the induced systematic errors,cosmic microwave background(CMB)anisotropy experiments measure temperature differences across the sky using pairs of horn antennas, temperature map is recovered from temperature difference obtained in sky survey through a map-making *** inspect and calibrate residual systematic errors in the recovered temperature maps is important as most previous studies of cosmology are based on these *** analyzing pixel-ring coupling and latitude dependence of CMB temperatures,we find notable systematic devia- tion from CMB Gaussianity in released Wilkinson Microwave Anisotropy Probe(WMAP)*** detected deviation cannot be explained by the best-fit LCDM cosmological model at a confidence level above 99%and cannot be ignored for a precision cosmology study.

关键词： cosmology cosmic microwave background methods data analysis

Estimating surface evapotranspiration using combined MODIS and CBERS-02.data

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Science china(Technological Sciences) 2005年第S2期48卷 145-160页

作者： XIN Xiaozhou1,2. LIU Qinhuo1, TANG Yong1,3, TIAN Guoliang1, GU Xingfa1, LI Xiaowen1,2. ZHENG Hongsheng4 & CHEN Jiayi4 1. State Key Laboratory of Remote Sensing Science, Institute of Remote Sensing Applications, Chinese Academy of Sciences, Beijing 100101, china 2. Research Center for Remote Sensing and GIS, Department of Geography, Beijing Normal university, Beijing 100875, china 3. graduate university of Chinese Academy of Sciences, Beijing 100039, china 4. Department of Atmospheric Physics, Peking university, Beijing 100871, china 1. State Key Laboratory of Remote Sensing Science Institute of Remote Sensing Applications Chinese Academy of Sciences 100101 Beijing China2. Research Center for Remote Sensing and GIS Department of Geography Beijing Normal University 100875 Beijing China3. Graduate University of Chinese Academy of Sciences 100039 Beijing China4. Department of Atmospheric Physics Peking University 100871 Beijing China

Spatial scale error is one of the most serious problems in the estimates of land surface heat fluxes of sensible and latent from satellite-borne data such as MODIS 1km resolution reflectance and emissive data. One of the feasible and economic ways to decrease the spatial scale error is to use high resolution land use class data together with the MODIS data. CBERS-02.data were used to produce land use class of Baiyangdian area, Hebei Province, china in the autumn of 2.04. The area ratio of each class in MODIS pixel was calculated, and used to derive the heat fluxes of the mixed pixel. The results showed that the estimated heat fluxes of soil, sensible and latent have been changed remarkably after using the high resolution land class data. It could be concluded from the comparison between simulated and ground-measured fluxes as well as the theoretical analysis that high resolution land class data are useful to diminishing the scale error of heat fluxes estimated from low resolution satellite data.

关键词： surface evapotranspiration spatial scale error MODIS CBERS land class.

Key technologies for solid state lighting

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Key technologies for solid state lighting