数字吴川GPS首级控制网建立及精度分析

数字城市的建设方兴未艾,控制网的布设作为数字城市建设中的一个普遍现象,历来为建设者所重视。该文以数字吴川GPS首级控制网建设为例,详细介绍了数字吴川GPS首级控制网技术设计、外业观测、基线解算、网平差及精度分析和可靠性检验的整个过程,包括外业观测和内业解算的技术要求及数据解算的过程,并对已知数据的合理性和GPS控制网成果的正确性进行了分析。     

临沂DMC航片生成正射影像的探讨

通过DMC影像资料分析了利用全数字摄影测量系统进行数字正射影像图的生产作业流程和实现技术线路，论述了外业及空三解算所需要的技术要求，说明了利用DMC影像进行大比例尺正射影像生产的可行性．最后指出了一些在实际生产过程中应注意的问题．     

美国战略计算计划的协调管理机制、实施特点及启示

随着信息技术的快速发展和数据量的暴增，算力成为数字时代重要的新型生产力。2016年以来，随着技术发展和需求的变化，美国重新制定了战略计算计划并更新了两个版本。文章分析了美国战略计算计划主要内容、协调管理机制及其“全政府”“举国”特点，结合我国算力发展中存在的主要问题，探讨了对我国算力发展的启示，包括制定算力研发战略、加强中央层面协调管理、培育先进计算产业、建立多种公私合作组织以凝聚各方力量等。     

计算机VR技术在数字媒体系统设计研究

计算机VR技术是利用电脑强大算力，以二进制创建虚拟仿真系统，让人意识进入其中，从而实现模拟现实的目的。目前VR技术在数字媒体系统中应用，主要解决将二维动态信息转换为三维信息，并在此过程中为用户提供加强感官体验，使用户有极强的沉浸感。目前VR技术结合了计算机图形学人机接口技术、多媒体技术、传感技术以及网络技术等。本文主要对计算机VR技术介绍，并阐述了数字媒体系统发展现状，针对VR技术对数字媒体系统的影响，阐明了两者的具体应用。     

边坡地质工程空间信息查询与量算方法探讨

随着科学计算可视化技术和地质信息计算机模拟技术的快速发展,工程地质可视化的需求也日益迫切。数字地质编录信息系统,以摄影测量理论为基础,综合运用近景数字影像和数字图像处理等技术,实现了工程地质编录数据的采集、处理、管理、分析和成果输出一体化,提高了专业信息化和生产力水平。通过对现有工程三维建模软件的不足,以边坡地质工程开挖体为研究对象,在数字地质编录系统生成的空间数据的基础上,对边坡地质工程空间信息查询和量算方法进行研究。     

基于BIM+数字孪生的高边坡施工检算动态反馈方法

为有效进行高边坡施工过程中不利工况的施工检算及动态反馈,以二次开发为依托,提出了基于参数化BIM模型及有限元方法快速进行高边坡不同工况稳定性检算的整套方案,并通过实际工程案例进行验证。首先,采用Revit二次开发技术实现不利工况高精度正向反馈至BIM模型;其次,将该BIM模型导入Abaqus中进行快速检算,基于Abaqus二次开发将有限元计算结果的自定义结构化输出;最后,采用Mesh重构方法将快速检算的结果向BIM环境反馈。结果表明：所提方案实现了数字孪生体与施工现场之间的同步关联,并且实现了数值计算结果与BIM环境互通。可见,BIM技术通过开发后可真实高效反映施工情况,并作为中间枢纽实现施工检算与成果管理,可为相关施工检算及BIM应用提供新思路。     

滑模观测器及其在无机械传感器永磁同步电机驱动系统的应用

为了取消永磁同步电机调速系统的机械传感器，电机转子的速度和位置通过测量定子电流和电压来估计，估计算法采用滑模观测器。采用逐段线性化处理技术，提出了一种滑模观测器在非线性系统中的新设计方法。根据这一方法，给出了用于永磁同步电机状态估计的具体算法。此算法简单，易于用数字计算机实现无机械传感器交流调速。通过数字仿真和实验测试，验证了所提算法的可行性。     

想想 做做

正一、读写算下面算式中,相同的汉字代表相同的数字,不同的汉字代表不同的数字。当"读""写""算"三个字各代表什么数字时,下面的算式成立?二、移火柴移动一根火柴棒,使下面的等式成立。三、插彩旗为庆祝三八妇女节,杨公小学在校门口插了12面红旗,他们还要在两面红旗之间     

一元总体最小二乘线性回归与解算分析

针对自变量为随机变量情形,在最小二乘准则下,一元线性回归所得到的回归参数估计及其拟合直线存在二义性问题,为确保解算结果的唯一性和一致性,需用总体最小二乘准则进行解算,对总体最小二乘准则进行了描述,利用奇异值分解方法,讨论了解算公式,最后用一数字算例,用最小二乘和总体最小二乘方法进行了计算和结果分析,得到了一些结论,此方...     

球壳振动问题的近似解

本文改进了Legendre函数的近似表达式,作者利用本文改进的Legendre函数的近似式来研究球壳的自由振动,提出了計算自振频率的较准确的計算理論。在准确理論基础上,文中获得球壳自振問題的扁壳理論和无矩理論,作者作了多种数字計算并提出了計算球壳自振頻率的实用近似公式。     

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

<正>~~     

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