用于干涉型光纤陀螺温度漂移辨识的RBF神经网络改进算法

针对干涉型光纤陀螺(IFOG)温度漂移的辨识,推导了径向基神经网络(RBFNN)中隐含层神经元、网络的抗噪声性能和拟合精度三者之间的关系,并在此基础上提出了一种新的径向基函数神经网络辨识学习规则.该方法具有很强的抗噪声性能,网络输出不会被陀螺噪声所污染,同时能动态地确定神经元数,辨识精度高,有效地避免了传统RBF网络学习算法中事先固定网络结构可能存在的盲目性.实验结果表明,该方法能够快速、准确地辨识IFOG的温度漂移.     

干涉式光纤陀螺的建模与仿真

为干涉式光纤陀螺 ( IFOG)系统建立一个完整的模型并对其进行计算机仿真是 IFOG研究过程中十分基础而又重要的工作 .本文根据 IFOG系统的实际结构特点 ,总结出系统的闭环控制为积分控制 ,由此建立了与实际情况最为接近的非线性动态模型和随机模型 ,并采用面向对象仿真技术对系统进行了动态仿真 .在随机仿真时 ,将各种仿真方法进行比较并结合 IFOG系统中随机噪声的特点 ,为 1 /f噪声选择了经频域处理的移动平均法 ( MA) ,为随机游走噪声选择了白噪声一次离散积分法 ,从而使随机仿真信号最大程度地模拟了实际信号     

基于全相位算法的自适应滤波算法

为减小实时信号的自适应处理时间,改善系统性能,在全相位数据空间概念的基础上,提出一种全相位自适应信号处理方法,并通过仿真对该算法在不同原始信号、不同噪声干扰的情况下进行了性能分析．在对该算法和经典的自适应算法在不同原始信号、不同噪声干扰的情况下进行了性能对比之后,提出了该算法的改进方案来改进输入信噪比小于0时的性能．结果表明,改进方案的输出误差性能达到甚至优于理想状态下的经典自适应算法, 从而验证了该算法及其改进方案的可行性和优越性．     

干涉式光纤陀螺的建模与仿真

根据干涉式光纤陀螺(IFOG)系统的实际结构特点，总结出系统的闭环控制为积分控制，由此建立了与实 际情况最为接近的非线性动态模型和随机模型，并采用面向对象仿真技术对系统进行了动态仿真．在随机仿真时， 将各种仿真方法进行比较，并结合IFOG系统中随机噪声的特点，为1／f噪声选择了经频域处理的移动平均法 (MA)，为随机游走噪声选择了白噪声一次离散积分法，从而使随机仿真信号最大程度地模拟了实际信号．     

带随机输出噪声的参考模型自适应系统

讨论了带随机输出噪声的线性时不变对象的参考模型自适应系统。提出一种适用于这种系统的混合自适应控制律,证明该系统所有信号的有界性,计算机仿真验证这种新的混合自适应控制律在存在随机输出噪声的系统中的性能。     

码分多址信道中的迭代译码及干扰消除技术

提出了一种码分多址在高斯白噪声信道中的迭代译码和干扰消除方案，在译码过程中，每个用户译码器的输出用来生成用户信号的软预测，预测值通过迭代译码和干扰消除得以改进，直到迭代收敛为止，然后对用户信号进行硬判决输出，最后，给出了模拟结果。结果表明系统性能将得到改善。     

码分多址信道中的迭代译码及干扰消除技术

提出了一种码分多址在高斯白噪声信道中的迭代译码和干扰消除方案,在译码过程中,每个用户 译码器的输出用来生成用户信号的软预测,预测值通过迭代译码和干扰消除得以改进,直到迭代收敛为 止,然后对用户信号进行硬判决输出,最后,给出了模拟结果*结果表明系统性能将得到改善.     

动态倍频PWM音频输出方案及其在dsPIC芯片上的实现

研究PWM在音频输出上的应用,提出一种可适于一般情况的动态倍频PWM的音频处理方法.该方法克服了传统音频输出中D/A转换器阻抗离散性影响、易受温度等环境干扰、成本和功耗相对较高的缺点,解决了基于PWM的D/A的精度与输出带宽的矛盾,并在Microchip dsPIC30F6014数字信号控制器上实现.该方案可适用于电子噪声严重的环境下进行音频信号传输,是性价比优良的音频信号恢复方案.     

一种高频率分辨率、高频率转换速度的周期方波发生器

提出一种新的方波信号发生器方案，该方案全部由数字电路组成，具有很高的频率分辨率与频率转换速度以及良好的噪声性能。     

一种应用于石英音叉增强型光谱的前置放大电路

针对目前石英增强光声光谱系统存在音叉输出高阻抗和受噪声辐射影响较大的不利因素,本文设计了一种高输入阻抗、高信噪比的前置放大器。该方案使用高输入阻抗运算放大器,减小音叉两级的信号线长度,使用两路信号相减的方式降低噪音和串接的音叉来提高信号,进一步提高信噪比。并在该放大器的基础上,使用压电陶瓷直接激发音叉的方法精确测量了音叉的共振中心频率和Q值。经实验检验,该放大器模块性能稳定、信噪比高且成本低。     

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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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.     

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。     

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