一种单芯电缆高速数据传输方案

生产测井一般利用单芯测井电缆实现地面系统和井下仪器的数据传输.为满足日益增长的大容量数据传输需求,在分析单芯测井电缆传输特性的基础上,提出基于正交频分复用调制解调技术的高速数据传输方案,克服了单芯测井电缆固有缺陷,提高了频带利用率,是生产测井实现高速数据传输较为理想的调制解调方案,对实际测井传输系统的研制具有重要的指导意义.     

基于小波包变换的多载波通信系统的实现

针对基于小波包变换的多载波通信系统的实现问题，提出了一种完整的基于小波包变换的多载波通信系统的实现方案．该方案由内外编码、小波包调制解调、信道估计及均衡、同步等部分组成，其基带部分（内外编码、交织、小波包调制解调）已在高速DSP上编程运行，并在TMS320C6701EVM板上进行了仿真测试．研究结果表明了该方案的可行性，由于基于小波包变换的多载波调制（WPT-MCM）较之正交频分复用（OFDM）有较多优势，本方案在高速数据传输领域及未来移动通信中具有良好的应用前景．     

基于前导训练序列的MB-OFDM信道估计

超宽带技术已逐渐成为无线通信领域研究、开发的一个热点,并被视为下一代无线通信的关键技术之一.UWB无线通信可以分成两种:无载波UWB、载波调制UWB.载波调制UWB有多种实现方案,主要有DS-CDMA UWB和MB-OFDM UWB.MB-OFDM作为UWB的一个重要候选方案,在频谱利用率、与其他窄带系统共存、抗干扰等方面有着出色的表现,而信道估计是无线通信领域的关键技术之一,是进行相关检测、解调、均衡的基础.文中在介绍MB-OFDM系统的构成、MB-OFDM系统信号结构以及超宽带信道模型的基础上,提出了一种基于前导训练系列的信道估计算法,对UWB信道条件下采用前导训练序列的LS估计和MMSE估计的性能进行了深入的分析和比较,最后给出了相关仿真结果.实验结果表明,利用前导训练系列的信道估计可以获得良好的性能.     

正交频分复用原理及应用分析

OFDM的基本思想是将所要传输的数据流分解成多个比特流，每个子数据流具有低得多的传输比特速率，并且用这些数据流去并行调制多个载波。由于符号持续时间的加长，因而它对多径时延扩展有较强的抵抗力，是对高速数据传输的一种潜在的解决方案，本着重讨论了OFDM基于FFT算法实现多载波调制的原理以及OFDM中的信道均衡技术，最后介绍了OFDM在HDTV传输系统和HFC网中的应用。     

浅谈多载波数字调制技术

多载波数字调制技术就是OFDM技术,在高速数字通信中是一种非常有潜力的技术。它将数据经编码后调制为射频信号。在经过特别计算的正交频率上同时发送多路高速信号。它不像常规的单载波技术,只在某一时刻只用单一频率来发送单一的信号。本文将对OFDM技术的基本原理进行详细分析,并阐述利用这一技术建立多载波并行传输系统,通过延长传输符号的周期,增强其抵抗回波的能力,为实际的系统应用提供有价值的理论参考。     

OFDM技术在802.11a WLAN中的应用研究

OFDM(正交频分复用)即多载波宽带数字调制技术,它能够有效地解决传输中产生的多径干扰以及消除码间串扰,可以提供54 Mbps的数据传输速率,具备频谱利用率高、信道均衡技术简单、信号调制解调易实现、纠错能力强等优点。OFDM技术的应用使得WLAN技术得到了更进一步的发展。利用MATLAB为开发平台,设计了OFDM仿真系统,实现OFDM系统各个基本环节的仿真算法,通过仿真结果对比分析可知,OFDM技术要比一般的单载波调制技术具有更强的抗多径干扰的能力,在无线局域网中具有较大的应用前景。     

OFDM性能的模拟研究

OFDM（正交频分复用）是一种多载波宽带数字调制技术，它能有效地克服传输中的多径干扰和消除码间串扰，适合于高速率的地面信道视频传输．就OFDM技术进行了较为详尽的分析，并对OFDM的传输特性进行了基于FFT算法实现Matlab软件模拟及模拟结果分析．仿真中采用16QAM和QPSK2种调制进行系统仿真比较分析，结果表明，采用QPSK调制解调OFDM系统的性能优于采用16QAM调制解调的OFDM系统．     

多径信道下OFDM系统采用2DPSK技术接收数据研究

正交频分复用技术由于具有较高的频谱效率,而且可以有效地对抗多径传输,已成为高速数据传输的关键技术。本文介绍了OFDM基本原理,并分析了多径信道下的OFDM信号,通过在发送端采用符号内2DPSK调制,在接收端相应地采用符号内2DPSK解调,可使接收数据的误码率降低。     

陈-Mbius四路载波数字通信系统的仿真

将几种常用数字波形的陈-Mbius逆变换作为四路载波数字通信系统数字输入信号的编码波形函数族,由其对二进制输入信号进行调制后,直接叠加在一个物理信道上进行传输.在接收端,用与各调制编码波形对应正交的数字波形对各路信号进行同步相干解调,从而构成新的相干调制解调系统.应用MATLAB平台对系统进行性能仿真,并与传统的相干调制解调系统的仿真结果相比较.结果表明,该系统具有更优异的抗强噪声与抗干扰的性能,可实现多路载波数字通信的直接叠加,大大节省系统的初始投资与运行费用.     

陈-M(o)bius四路载波数字通信系统的仿真

将几种常用数字波形的陈-M(o)bius逆变换作为四路载波数字通信系统数字输入信号的编码波形函数族,由其对二进制输入信号进行调制后,直接叠加在一个物理信道上进行传输.在接收端,用与各调制编码波形对应正交的数字波形对各路信号进行同步相干解调,从而构成新的相干调制解调系统.应用MATLAB平台对系统进行性能仿真,并与传统的相干调制解调系统的仿真结果相比较.结果表明,该系统具有更优异的抗强噪声与抗干扰的性能,可实现多路载波数字通信的直接叠加,大大节省系统的初始投资与运行费用.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

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.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

A computer generator for randomly layered structures

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

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

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。     

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.     

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

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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