高误码率链路上多媒体通信的复接方案

针对高误码率链路上的多媒体通信,提出了一种高效率、高鲁棒性的复接方案。方案采用了双层的数据复接结构,结合了定长帧和变长帧复接方案的优点,在高误码率链路上提供了良好的同步特性。同时多种业务的数据流能灵活地进行复接,从而提高了整体的通信效率。该方案针对实时和非实时业务进行复接,有效降低了实时业务的通信时延。实验证明:与ITU-TH.223附录C中提出的方案相比,该方案在10-2随机误码的链路上,通信效率提高了17.3%。     

基于DSP的CVSD与PCM编码全数字转换技术

提出并实现了一种基于DSP的 16Kbit/sCVSD(连续可变斜率增量调制 )编码与 6 4Kbit/sA律PCM(脉冲编码调制 )编码的全数字转换技术 .相对于现有的编码转换系统 ,此种技术符合单值对应法则 .实验证明 ,当CVSD误码率≤ 2× 10 -5且PCM误码率≤ 1× 10 -5时 ,采用该转换算法可以做到多次转换无误差积累     

一种新型软件帧同步算法的研究与实现

同步字提取是遥感卫星地面记录与存档系统设计中的关键技术之一。提出了一种新型软件帧同步算法——基于查表判决方式的软件帧同步算法,并对该算法的基本原理作了详细介绍。该算法在实际应用中获得了良好的效果。     

一种高灵活性HEVC帧内编码器前端设计

本文基于一种两级流水的高灵活性HEVC帧内编码器架构,完成了其前端设计,主要完成块大小划分和码率控制2个功能.针对这2个功能的算法优化,提出了一种基于梯度的帧内编码器块大小判决快速算法和一种低复杂度的码率控制算法,并最终用软硬件协同的方式将这两种算法在硬件中实现.     

基于OOK体制的激光统一测控系统设计与实现

激光统一测控系统采用激光链路同时实现高速通信、高精度测距和时钟同步.为了实现激光统一测控系统,根据异步应答测距方法,设计研制了基于OOK体制的激光统一测控系统原理样机,样机包含两套激光模拟终端,分别向对方发送包含测量数据帧的激光调制信号,并记录发送测量数据帧和接收测量数据帧的本地钟时间,据此计算得到距离、钟差、相对频差的测量结果.样机有线对接试验表明,在码率为2.5 Gbit/s的双向激光通信条件下,测距随机误差为6.2 mm,测距系统误差为1.3 mm,钟差测量随机误差为27 ps,相对频差测量随机误差为2.7×10-13.该样机为激光统一测控设备的研制和应用提供了技术支撑.      

卷积码及其维特比译码算法的软件实现

提出了数字通信系统中在信道受到干扰时信道译码器检测或修正解调器送来错误信息的一种软件实现方案，该方案应用VisualC 6.0软件技术实现了卷积编码器和维持比译码器功能，它不仅译码算法简单，易实现，而且可以得到较大的编码增益，具有良好的纠错编码功能，是一种软件方法的前向纠错编码技术，实验结果表明：应用软判决维持比译码算法时的误码率低于应用硬判决算法的误码率，一般要比硬判决算法多大约2dB的增益；约束长度越大误码率赵低，译码性能越好，在码率和约束长度不变时，硬判决算法的执行速度比软判决算法快。目前，该方案已应用于高精度网络彩色激光打印机，并获得好评。     

G.729语音编解码系统的帧同步实现算法

基于帧结构的中低速率语音编解码算法G.729在应用中经常会遇到码流的帧同步问题。为克服传统的帧同步方法会增加码率的缺点,提出了一种通过修改G.729帧结构实现的同步方法。结合G.729的特点,通过比较选择出一种性能较好的失步检测算法,并设计了类似结构的同步捕捉算法。最后将这两部分算法有机地结合起来以省去各部分的初始化过程并使它们协同工作,从而大大地提高了整体性能。同时还给出了详细的性能分析,结果显示出了良好的性能指标,在实际应用中也已得到了证明。     

低信噪比下的并行多延时相关帧同步算法

为提高正交频分复用(OFDM)在低信噪比环境下的同步性能和抗噪能力,提出了一种并行多延时相关帧同步算法。该算法充分利用帧的前导训练符号周期重复的特点,在接收端滑动窗中并行处理多种延时相关运算,通过阈值判决进行帧检测,同时完成载波频率同步,进而实现OFDM帧同步。该算法无须改动现有系统的物理帧结构,也不增加系统延时。理论分析和在加性G auss白噪声信道下的误帧率(FER)性能仿真证明:该算法的误帧率约为现有参考方案的1/10,信噪比(SNR)比参考方案提高约7 dB,能够工作在信噪比小于-1 dB的环境。     

基于H.264/AVC的帧间编码快速算法

为了减少H.264帧间模式判决的复杂度,提高编码速度,提出了一种帧间模式选择快速算法.该算法对所有编码模式进行综合分析,利用当前宏块的绝对差值以及率失真值对所有编码模式进行三级分裂,在一定误差范围内能够快速寻找最佳编码模式,加快模式判决过程.通过基于H.264/AVC测试模型JM86的仿真实验表明,在保持图像质量和码率基本不变的情况下,该算法可以有效提高编码速度.     

无线传输中的循环冗余校验码纠错应用扩展

以国际标准CRC-CCITT循环冗余校验码为研究对象,利用近世代数多项式理论证明其奇偶校验性质、最小码距和纠正单比特错误能力.在分析无线通信系统中单比特错误帧分布的基础上,提出一种利用CRC纠正每帧单比特错误的新方案.仿真结果证明,应用CRC纠错可以改善比特误码率、帧错误率和吞吐量,特别是在原始误码率为10-3～10-5区间吞吐量有显著提高;在不改变原有无线通信系统结构的条件下提高了数据传输性能.给出了新方案的一种低复杂度的实现方法.     

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.     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that