斜测电离图F2层描迹的自动判读

将数字图像处理中的形态学算子和反演技术相结合,发展了一种新的斜测电离图F2层描迹自动判读方法.该方法从电离图预处理、电离图描迹提取和参数提取三大模块出发,实现了斜测电离图F2层描迹的自动判读,并用实际探测数据进行了验证及统计分析.结果显示:该方法适用于不同高角波状态的斜测电离图,能够快速、准确地拟合F2层寻常波描迹且不受毛刺的影响,并且提取的F2层最大可用频率和最小群路径的可接受率分别为95.1%和92.7%,表明该方法具有较好的可靠性、通用性,能有效应用于电离层实时斜测研究领域.     

海南地区扩展F统计特性及行星波扰动观测

为研究中国低纬地区扩展F(SF)的发生时间和季节特性以及行星波扰动对其影响,利用2013年海南三亚综合观测站DPS-4D数字测高仪观测到的电离层频高图数据,统计分析了扩展F的开始和持续时间及其季节变化;提取了电离层虚高,从虚高的逐日变化中获取了F层上抬时间和行星波扰动特征,并对上抬期间电离层F层最小虚高(h'F)、临界频率(fo F2)等参数进行了小波分析.结果表明:海南地区扩展F类型主要为RSF,其季节性最大值(51%)出现在分点季,RSF在日落后和午夜后均有发生,而FSF主要在夏季午夜后出现;海南地区电离层虚高在日落后反转增强(PRE)期间有明显上抬现象,电离层特征参数中存在周期为准2d、5d以及10d的行星波扰动,它通过调制电离层F区发电机电场的方式激励扩展F的发生和发展.     

电离层测高仪高速采集系统设计

电离层测高仪数据采集是进行频高图标定及电离层参数研究的基础,其采样的精度对频高图标定有着重要的影响.采用基于IP硬核方案的PCI Express总线测高仪高速采集系统,设计了以FPGA (EP4CGX150CF23C8N)为系统控制核心和高性能模数转换器ADC(LTC2192)作为数据采集系统硬件主要模块.利用Visual C++6.0的平台完成采集系统驱动程序及编写上位机应用软件实现了软件设计模块.利用数字测高仪平台对武汉、北京、海南地区电离层进行常规观测,对采集的频高图完成本地存储.分析采集的频高图与原始数据,结果表明:利用设计的PCI Express总线采集系统相比原ISA总线在精度与DMA传输速度上有较大提高,采集得到的频高图O波与X波轨迹更为清晰.原始数据图显示出回波信号的幅度变化与多普勒频移.     

武汉地区 Es 回波多普勒特性的观测与分析

利用最新研制的高频多普勒接收机对10MHz BPM授时信号进行了长时间监测,应用数字信号处理技术,获取连续高精度的多普勒频移,结合PDI-2数字测高仪观测到的电离层频高图数据,实现了对Es层反射回波特性的研究.构建了电离层不规则体反射电波理论模型,仿真出在该模型下电离层反射回波的多普勒谱特性,并结合高频多普勒接收机的实测数据,绘制了Es回波的多普勒频移曲线,结果表明:仿真结果与实测结果很好地吻合,并基于此估算出了Es层不规则体的运动速度.     

敏捷数字测高仪正交有源环天线设计与应用

为减少接收天线占地面积,降低架设难度,实现敏捷数字电离层测高仪的流动组网观测,设计了一种可用于1 MHz～30 MHz电离层回波探测的小型正交有源环天线,配合敏捷数字电离层测高仪,组成了具有多种工作模式的电离层高频回波探测系统.测试结果表明:该正交有源环天线与传统的正交折合偶极子天线相比,接收到的频高图质量基本相当,均可接收到电离层多次回波并区分电离层回波的O波与X波.结果表明:正交有源环天线在保证探测频高图质量条件下很好地解决了接收天线小型化问题,具有性价比高、架设简单的优点.为观测场地受限及需要临时流动观测的实际应用场景提供了良好的解决方案,具有广阔的应用前景.     

重力梯度张量的拟BP神经网络反演

基于重力梯度张量是反映重力场空间变化率的参数,比传统的重力异常具有更高的分辨率和更丰富的信息,将改进的BP神经网络算法应用于重力梯度张量的反演中并分析其反演效果.该算法是一种基于RPROP算法的拟BP神经网络反演算法,采用三层神经网络结构,用隐层神经元表示物性单元的密度值,根据RPROP算法自动修改各单元密度值,从而得出场源空间的密度分布.研究结果表明:采用这种算法对重力梯度张量进行反演计算,收敛速度快,对初始模型依赖性小,可准确反映出异常体形态特征和密度特征.     

免振捣粉煤灰混凝土抗压强度的神经网络预测

为了解决免振捣粉煤灰混凝土抗压强度预测问题,采用BP神经网络方法通过免振捣粉煤灰混凝土不同配合比训练网络预测其抗压强度,对于BP网络的隐层节点属于不确定层,采用三层结构的BP网络.但隐含单员个数仍未知。在实验过程中将隐含层的神经单元个数作为一个参数试验,结果表明BP神经网络的隐层节点数目对预测精度有较大影响。通过分析得出采用BP神经网络对免振捣粉煤灰混凝土抗压强度预测是可行的。     

基于在线学习误差反传算法的仿真伺服系统设计

针对无人机(UAV)仿真伺服系统的驱动模型,提出了一种将误差反传算法用于UAV仿真伺服系统在线学习设计的新方案.在该算法中采用了BP神经网络的基本思想,设计了两输入、单隐层、两输出在线学习策略,输入层分别为给定指令信号和反馈数字解算后的位置信号;隐含层单元数为12个;输出层设为2个输出单元,即经在线学习误差反传算法学习训练后的数字位置和速度,其中位置控制器采用自调节比例-积分-微分(PID)控制,速度通过数字/模拟(D/A)转换后传送到速度控制器,设定精度误差指标为0.05,训练样本数为30.用研制的UAV仿真伺服系统对UAV光纤陀螺传感器进行含实物半物理实时仿真实验,结果表明,该在线学习误差反传算法控制方案的UAV仿真伺服系统具有收敛性好、动态响应快、鲁棒性强的特点.     

BP神经网络隐含层单元数的确定

本文针对BP神经网络隐含层单元数难以确定的问题,提出了一种改进的方法,并通过实验证明该方法有效的减少了验证次数,提高了确定隐含层最佳单元数的效率,具有较高的应用价值.     

基于S变换和弹性神经网络的电能质量扰动分类

提出了基于S变换和弹性BP神经网络结构(RPROP)的电能质量扰动自动分类方法。通过S变换对电能质量扰动信号进行时频分析,有效实现对各种扰动信号时频特征量的输出,并确定特征量的最优组合来增加弹性BP神经网络分类的精度。同时研究了在不同噪声条件下弹性BP神经网络分类的敏感度。测试结果显示,该方法能有效地对电能质量扰动信号进行分类。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to