检索结果-南通市图书馆

Relationships between ionospheric parameters derived from ionosonde observations and characteristics of post-sunset GHz scintillation during high solar activities(2012−2013)at Sanya(18.3°N,109.6°E),China

引用

Earth and Planetary Physics 2023年第3期7卷 389-406页

作者： JunJie luo Ying Xiong weihua luo ZhengPing Zhu ChaoWan Fan College of Electronic and Information Engineering South-Central Minzu University430074 WuhanChina Hubei Key Laboratory of Intelligent Wireless Communications South-Central Minzu University430074 WuhanChina Hubei Engineering Research Center of Intelligent Internet of Things Technology South-Central Minzu University430074 WuhanChina

In this study,we present characteristics of post-sunset GHz scintillation occurrence and their correlations with ionospheric parameters derived from ionosonde observations in high solar activity years(2012−2013)of solar cycle 24 at Sanya(18.3°N,109.6°E;dip lat.:12.8°N),*** analyzed data include the F_(2)-layer’s critical frequency(foF_(2)),peak height(h_(m)F_(2)),and minimum virtual height(h’F),as well as the scale height around the F_(2)-layer peak(H_(m)),and virtual height(h’F_(5))and true height(hF_(5))measured at 5 *** have investigated relationships between the equinoctial asymmetry of these scintillations and these ionospheric *** addition,we calculate the growth rates of Rayleigh−Taylor instability on the basis of the ionosonde measurements and theoretical models,*** find that the equinoctial asymmetry of scintillation onset time is associated with the scale length of the vertical electron density gradient(L),which has been shown to affect the growth of Rayleigh−Taylor instability at the bottom of the *** seasonal variations of foF_(2),H_(m)and scale length of vertical electron density gradient appear to cause the seasonal variations of scintillation occurrence;the equinoctial asymmetry of scintillation occurrence rate over low latitudes appears to be related to background electron density and vertical drifts in the F-layer around time of *** study is required to explain the observed correlational weakness in low latitudes between scintillation strength,represented by the daily maximum S4,and daily maximum values of foF_(2),h_(m)F_(2),h’F,H_(m),and also the drifts.

关键词： equatorial ionosphere scintillation low latitude iononsonde equinoctial asymmetry

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

ACCURATELY DETERMINING PROPAGATION VELOCITY OF CORTICAL SPREADING DEPRESSION IN RATS BY OPTICAL INTRINSIC SIGNAL IMAGING

引用

Journal of Innovative Optical Health Sciences 2010年第2期3卷 103-108页

作者： XIAOLI SUN PENGCHENG LI weihua luo BIYING GONG QINGMING luo Britton Chance Center for Biomedical Photonics Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Wuhan 430074 P.R.China

Cortical spreading depression(CSD)is a wave of neuronal and glial depolarization that propagates across the cortex at a rate of 2–5mm/min accompanied by reversible electroencephalogram(EEG)suppression,a negative shift of direct current(DC)potential,and change of optical intrinsic signals(OIS).Propagation velocity of CSD is an important parameter used to study this *** is commonly determined in an electrophysiological way that measures the time required for a CSD wave to pass along two *** the electrophysiology technique fails to reveal the spreading pattern of CSD,velocity calculated in this manner might be *** this study,we combined the electrophysiological recording and OIS imaging(OISI)for detecting changes in DC potential and OIS during CSD *** optical method based on OISI to determine the CSD velocity,which is measured by generating a series of regions of interest(ROI)perpendicular to the advancing wavefront along propagation direction of CSD at different time points and then dividing by the distance between ROIs over time,is *** of the accuracy of the two approaches in determining the CSD velocity is made as *** average rate of 33 CSDs is 3.52±0.87mm/min by use of the optical method and 4.36±1.65mm/min by use of the electrophysiological *** of the information about spreading pattern of CSD provided optically,the velocity determined by OISI is of smaller deviation and higher accuracy.

关键词： Cortical spreading depression velocity optical intrinsic signal imaging electrophysiology accuracy

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

TWO-DIMENSIONAL VISUALIZATION OF THE PROPAGATION SPEED OF CORTICAL SPREADING DEPRESSION IN RAT CORTEX

引用

Journal of Innovative Optical Health Sciences 2010年第1期3卷 75-80页

作者： TINGTING XU PENGCHENG LI SHANGBIN CHEN weihua luo Britton Chance Center for Biomedical Photonics Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Wuhan 430074 P.R.China

Cortical spreading depression(CSD),which is a significant pathological phenomenon that correlates with migraines and cerebral ischemia,has been characterized by a wave of depolarization among neuronal cells and propagates across the cortex at a rate of 2–5mm/*** the propagation pattern of CSD was well-investigated using high-resolution optical imaging technique,the variation of propagation speed of CSD across different regions of cortex was not well-concerned,partially because of the lack of ideal approach to visualize two-dimensional distribution of propagation speed of CSD over the whole imaged ***,we have presented a method to compute automatically the propagation speed of CSD throughout every spots in the imaged *** this method,temporal clustering analysis(TCA)and least square estimation(LSE)were first used to detect origin site where CSD was *** the origin site of CSD as the origin of coordinates,the data matrix of each image was transformed into the corresponding points based on the polar-coordinate ***,two fixed-distance regions of interest(ROIs)are sliding along with the radial coordinate at each polar angle within the image for calculating the time lag with correlating ***,we could draw a twodimensional image,in which the value of each pixel represented the velocity of CSD when it spread through the corresponding area of the imaged *** results demonstrated that the method can reveal the heterogeneity of propagation speed of CSD in the imaged cortex with high fidelity and intuition.

关键词： Cortical spreading depression least square estimation propagation speed cross correlogram

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Transient stability risk assessment of power systems incorporating wind farms

引用

Journal of Modern Power Systems and Clean Energy 2013年第2期1卷 134-141页

作者： Lu MIAO Jiakun FANG Jinyu WEN weihua luo State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and TechnologyWuhan 430074China Liaoning Electric Power Company Limited Shenyang 110006China

Large-scale wind farm integration has brought several aspects of challenges to the transient stability of power *** paper focuses on the research of the transient stability of power systems incorporating with wind farms by utilizing risk assessment *** detailed model of double fed induction generator has been *** penetration variation and multiple stochastic factors of power systems have been *** process of transient stability risk assessment based on the Monte Carlo method has been described and a comprehensive risk indicator has been *** investigation has been conducted into an improved 10-generator 39-bus system with a wind farm incorporated to verify the validity and feasibility of the risk assessment method proposed.

关键词： Wind farm integration Transient stability DFIG Risk indicator Wind farm location

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

EFFECTS OF NAAG AND MPEP ON RAT CORTICAL SPREADING DEPRESSION

引用

Journal of Innovative Optical Health Sciences 2010年第2期3卷 123-129页

作者： ZHEN WANG weihua luo XIAOLI SUN PENGCHENG LI SHANGBIN CHEN QINGMING luo Britton Chance Center for Biomedical Photonics Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Wuhan 430074 P.R.China

Cortical spreading depression(CSD)is a pathophysiological *** are sufficient evidences to prove that CSD plays an important role in some neurological ***,exact mechanisms of its initiation and propagation are still *** studies showed that glutamate receptors could be concerned with CSD,but those studies were mostly performed oriented to ionotropic glutamate receptors(iGluRs).There is relatively little report about effects of metabotropic glutamate receptors(mGluRs)on ***,we applied optical intrinsic signal imaging(OISI)combined with direct current(DC)potential recording to examine influences of some mGluRs antagonist(or agonist)on CSD propagation in rat’s brain,to indirectly validate actions of some mGluRs on *** found that N-acetyl-l-aspartyl-l-glutamate(NAAG,an agonist at mGluR3)inhibited the propagation of CSD,and the inhibition was gradually developed with ***,6-methyl-2-phenylethynyl-pyridine(MPEP,an antagonist of mGluR5)did not produce any significant alterations with the CSD *** findings suggest that mGluR3 could play an important role in the CSD propagation,but the activity of mGluR5 was comparatively *** findings can help to understand the propagation mechanism of CSD,and consider the therapy of some neurological diseases involved with CSD.

关键词： Metabotropic glutamate receptors cortical spreading depression optical intrinsic signal imaging direct current potential rats

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Spatial and Temporal Response of Equatorial Ionization Anomaly to the 17 March 2015 Storm from Global Ionosphere Map

引用

Wuhan University Journal of Natural Sciences 2018年第5期23卷 429-437页

作者： MEI Xuefei luo weihua CAI Hongtao ZHU Zhengping School of Electronic Information Wuhan University Wuhan 430072 Hubei China College of Electronic Information and Engineering South- Central University for Nationalities Wuhan 430074 Hubei China

The responses of Equatorial Ionosphere Anomaly（EIA） to the storm occurred on 17 March 2015 were studied using Global Ionosphere Map（GIM）. The variations of Total Electron Content（TEC）, latitudinal TEC gradients and the rate of latitudinal TEC gradients in EIA regions were investigated in 75？E, 110？E and-60？E longitudinal sectors. The results from the GIM data showed that the distributions of the latitudinal gradient of TEC became monotonous in three longitudes on 18 March（the first day of the recovery phase）, but the variations were different. On 18 March, the magnitudes of latitudinal gradients decreased in spatial and temporal in 75？E and 110？E, which means the EIA was suppressed during the recovery phase of the storm, especially in 110？E. The magnitudes of latitudinal TEC gradients showed an obvious increase in spatial and temporal in-60？E. The SAMI2 reproduced the suppression of EIA with a disturbance dynamo electric field, which indicated that the physical process controlled the behaviors of the plasma during the recovery phase of the storm.

关键词： ionosphere Equatorial Ionization Anomaly storm Global Ionosphere Map

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Characteristics of Ionospheric North-South Asymmetry and Their Relationship with Irregularity

引用

Wuhan University Journal of Natural Sciences 2015年第3期20卷 240-246页

作者： luo weihua ZHU Zhengping LAN Jiaping LI Xuejing College of the Electronic Information and Engineering South-Central University for Nationalities Electronic Information School Wuhan University

Using the empirical ionospheric model, the flux-tube integrated electron density and the ratio between the F-region Pedersen conductivity and the total E- and F-region Pedersen conductivity are calculated to investigate the characteristics of the ionospheric asymmetry after sunset during a solar cycle. Furthermore, two indices representing the asymmetric strength of the parameters respectively are defined to study its relationship with the occurrences of the irregularities during different seasons and with different solar activities. The results indicate that the electron density and the Pedersen conductivity ratio show north-south remarkable hemispheric asymmetry at different solar energy levels. The asymmetric strengths represent the dependence on seasons and solar activities, and their variation depending on seasons and solar activities show a negative correlation with the occurrences of the equatorial irregularities and also have a negative relation with the linear growth rate of the generalized Rayleigh-Taylor instability.

关键词： ionosphere asymmetry electron density Pedersen conductivity irregularity

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A Parameterized Preconditioner for Incompressible Navier-Stokes Equations

引用

数学计算（中英文版） 2013年第4期2卷 105-108页

作者： weihua luo Tingzhu Huang School of Mathematical Sciences University of Electronic Science and Technology of China Chengdu Sichuan 611731 P. R.China Key Lab of Numer. Simulation of Sichuan Province Univ. Neijiang Normal University Neijiang Sichuan 641112 PR China

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

面向大规模语料的语言模型研究新进展

引用

计算机研究与发展 2009年第10期46卷 1704-1712页

作者：骆卫华刘群白硕中国科学院研究生院北京100049 中国科学院计算技术研究所智能信息处理重点实验室北京100190 上海证券交易所上海200120

N元语言模型是统计机器翻译、信息检索、语音识别等很多自然语言处理研究领域的重要工具.由于扩大训练语料规模和增加元数对于提高系统性能很有帮助,随着可用语料迅速增加,面向大规模训练语料的高元语言模型(如N≥5)的训练和使用成为新... 详细信息

N元语言模型是统计机器翻译、信息检索、语音识别等很多自然语言处理研究领域的重要工具.由于扩大训练语料规模和增加元数对于提高系统性能很有帮助,随着可用语料迅速增加,面向大规模训练语料的高元语言模型(如N≥5)的训练和使用成为新的研究热点.介绍了当前这个问题的最新研究进展,包括了集成数据分治、压缩和内存映射的一体化方法,基于随机存取模型的表示方法,以及基于分布式并行体系的语言模型训练与查询方法等几种代表性的方法,展示了它们在统计机器翻译中的性能,并比较了这些方法的优缺点.

关键词：语言模型数据压缩随机存取模型布隆过滤器分布式并行体系

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

背景电离层半球不对称特征研究

引用

电波科学学报 2013年第5期28卷 920-925,940页

作者：罗伟华徐继生中南民族大学电子信息工程学院湖北武汉430074 武汉大学电子信息学院湖北武汉430072

由于背景电离层关于磁赤道存在南北不对称,可能对赤道电离层中的等离子体不稳定性过程产生影响,背景电离层参数的变化可能作为不规则结构出现和闪烁发生的前兆.本文利用通量管积分方法,研究背景电离层电子密度和Pedersen电导率的半球不... 详细信息

由于背景电离层关于磁赤道存在南北不对称,可能对赤道电离层中的等离子体不稳定性过程产生影响,背景电离层参数的变化可能作为不规则结构出现和闪烁发生的前兆.本文利用通量管积分方法,研究背景电离层电子密度和Pedersen电导率的半球不对称特征,发现积分电子密度N和积分Pedersen电导率珟ΣP以及F区积分电导率珟ΣF P与E区和F区积分电导率之和珟ΣE+F P的比值珟ΣF P/珟ΣE+F P的不对称强度随季节和太阳活动的变化规律与实验观测的不规则结构和闪烁活动的变化规律存在联系.这表明背景电离层电子密度和Pedersen电导率的分布对不规则结构和闪烁活动的出现有重要影响,表征积分电子密度和积分Pedersen电导率不对称强度的参数IN和IP可作为一种应用于电离层闪烁预报系统的预报指数.

关键词：电离层通量管不规则结构闪烁不对称

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：