丰富多彩的进位制

“7”是多少? 对于这个问题,正确的回答应是:不知道。因为字符“7”给出的信息还不够,要知道它的意义,必须知道它在数字中的位置,还要知道这个数字是按什么进位制进位的。基数和进位制表示事物个数的数叫做基数,如1,2,3等。以什么基数作为进位的标准呢?丰富多采的生活,产生了丰富多采的进位法,如以基数10为标准时,是“逢十进一”这就是我们举的十进制,同理有二进制、三进制、十六进制、六十进制等。这些进位制都来自生活,又在生活中演变,承担着不同的角色。     

基于变码重光正交码光码分多址系统的性能分析

光正交码是一种具有良好自相关性和互相关性的（0,1）序列,被广泛的运用于光码分多址（OCDMA）系统.由于光正交码中所有码字的码重都固定不变,使得码字的容量不大.我们提出了变码重光正交码,并对其进行了理论分析.最后,给出了数值仿真结果.结果表明,采用变码重光正交码的系统无论是在可接入用户数还是在系统误码率上都优于采用固定码重光正交码的系统.研究结果对OC-DMA系统参数的选取具有一定的参考价值.     

利用集成全加器设计码制转换电路

介绍了用集成超前进位全加器设计码制转换电路的理论和方法，并举例说明其应用。     

完全互补码CDMA系统的性能仿真

为了减小直接扩频CDMA系统中各用户的多址干扰,研究了一种特殊的扩频序列--完全互补码.介绍了完全互补码的概念和性质,给出了一种完全互补码的生成方法,提出了一种新的扩展完全互补码的方法,讨论了基于完全互补码的CDMA系统模型.对该模型在加性高斯白噪声信道和瑞利衰落信道中的性能进行了仿真,并与基于Gold序列和m序列的CDMA系统的性能进行了分析比较.结果表明,基于完全互补码的CDMA系统具有很好的抗多址干扰性能.     

Kasami扩频序列的研究

介绍了扩频序列的研究、发展情况和Kasami扩频序列的生成方法 .提出了当移位寄存器的级数n =2 (模 4 )时 ,一种新的序列构造方法 ,所得到的两个集合与Kasami大集合序列的相关特性一致 .并与Gold码、Kasami小集合序列码进行了比较分析 ,进一步拓展了扩频码的生成方法 .     

数字与数码

数字与数码在一般情况下常常不加区别而混用，本文从记数法角度对它们进行区分，对数字与数码的起源，记数的表达形态，进位基数的选择，进位的表示方式以及数字与数码的相互影响和发展趋势等方面作了阐述，指出区别数字与数码在数学史研究中的作用，并以中外有代表性的记数方法为例加以说明。     

多通道直扩信号并行捕获算法

为了缩短多通道直接序列扩频信号的捕获时间,提出了一种新的多通道并行捕获算法.该算法将多个通道的伪码序列进行叠加,形成一个新的伪码序列,由新的伪码序列和多通道直扩信号进行相关,检测到信号后再判决具体通道.分析和仿真结果均表明,提出的算法在不增加实现资源的情况下,以少量降低相关信噪比为代价缩短了捕获时间,适用于多通道直扩信号的快速捕获.     

基于串行RapidIO的舰载相控阵雷达波束控制设计

为了提高舰载相控阵雷达波束指向捷变能力,设计了一种分布式波控系统,其中传输方式采用串行RapidIO,波控主机采用PowerPC矢量运算处理器,子阵运算模块为FPGA。重点推导了舰载相控阵雷达波控码的公式,实现了RapidIO的初始化编程,以及波控主机的波控任务编程。测试波控码的计算和RapidIO通信时间,设计方案能够满足舰载相控阵雷达的波束切换时间指标。     

基于FPGA的波控系统设计与实现

根据系统提出的接口以及模块化设计要求,文中提出了一种基于FPGA的波控系统设计方案,并且设计了波控码计算和波束控制软件,软件仿真和实际运行都验证了该方案的可行性,实现了对波控码的高速并行计算和对各单元通道的并行同步控制.     

十进位数化为P进位数的数位换算公式与性质

一般地我们需要将抽象的实数以一种具体的形式来表示,通常实数都采用十进位小数的形式来表示,但在实际应用中也需要将实数以其它形式的进位制小数来表示。本文给出将任意实数在通常情形下的十进位小数表示转化为更一般的P进位小数表示形式的数位换算公式及性质。     

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.     

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.     

A computer generator for randomly layered structures

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

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     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.