Implement of Timing Synchronization for ofDM Underwater Communication System on FPGA

结合水声信道和线性调频(lfM)信号的特点,采用lfM信号作为OfdM水声通信系统的定时同步信号。介绍lfM信号的产生和检测原理,并在fPgA上实现了lfM定时同步信号的产生和同步信号的检测。通过实验室水池实验,验证了该方案的可行性。Based on characteristics of underwater acoustic channel and Linear Frequency Modulation(LFM) signal,LFM signal is adopted for timing synchronization signal of ofDM underwater communication system.The generation and detection principle of LFM signal are summed up.Then the scheme based on the theory above is implemented on Field Programmable Gate Array(FPGA).Finally,the result of pool test shows the feasibility of the scheme.国家自然科学基金资助项目(60772141

Convolutional decoder design and DSP implementation of underwater acoustic ofDM system

纠错编码是水声OfdM通信系统必须采用的关键技术。本文从译码性能和工程实现角度出发,采用卷积交织、卷积编码和VITErbI软译码相结合的差错控制方案,通过仿真和水池实验确定其参数,并在TMS320dM642上实现。在dSP实现时,卷积交织采用查表法,VITErbI译码采用蝶形运算宏定义等处理方法,极大地提升了运算速度,保证了卷积码的实时性。最后通过海洋实验验证了其译码性能。Error correction coding is a key technology in underwater acoustic ofDM communication system.Convolutional interleaving,convolutional coding and Viterbi soft decoding are implemented on TMS320DM642 in underwater acoustic ofDM system.Look-up table method used in convolutional interleaving and definition of butterfly macro in Viterbi decoding improve DSP computing speed and ensure real-time communication.Finally,the performance of the decoder in sea test is given.国家自然科学基金资助(No.60772141

减阻沟槽边界层相干结构展向拓扑的分层可视化

采用高时间分辨率粒子图像测速系统(TR-PIV),分别对沟槽壁面及光滑壁面平板湍流边界层速度矢量场的时间序列进行了精细测量,并利用新象限分裂法及新条件采样与相位平均技术,在李山等人对数区结果的基础上,对光滑壁面和沟槽面湍流边界层近壁区及外区相干结构二维空间拓扑的形态进行了进一步地对比研究。结果表明:在近壁区和对数区内,与光滑壁面相比,不论喷射事件还是扫掠事件,减阻沟槽使得相干结构法向脉动强度降低最为明显,即相干结构在法向上的动量和能量交换减弱,削弱了其对湍流产生的贡献;而进入外区以后,减阻沟槽对法向脉动速度分量和展向涡量在喷射和扫掠过程中影响比内区要小,说明沟槽主要影响湍流边界层内区结构,且以..

Research and implementation of underwater acoustic real-time voice communication prototype based on MELP

根据水声通信的复杂信道特性,对混合激励线性预测语音编码MElP算法和低密度奇偶校验码ldPC的结合进行了研究,设计了基于ArM+dSP的多载波水声实时语音通信样机。经水池实验测试,系统表现出良好的实时性和语音可懂度性能,可分辨出不同说话人的声音。Taking the complexity of the underwater acoustic communication channel characteristics into account,the combination of mixed excited linear prediction(MELP) and low density parity check(LDPC) were studied and a multi-carrier underwater acoustic real-time voice communication prototype based on ARM+DSP was designed.By the expreimental test in pool,the proposed system showed a good real-time and voice intelligibility performance,and could distinguish the voice of different speakers.中央高校基本科研业务费专项资金资助(2010121062

分子对接预测H5亚型禽流感病毒的广谱中和表位

H5N1禽流感病毒已经在亚洲、欧洲和非洲广泛传播,造成了巨大损失.最近我们鉴定出一株对多种来源的H5N1代表株均有良好中和活性的、识别H5亚型血凝素(hemagglutinin,HA)的广谱单克隆抗体8H5,它对寻找克服禽流感高变性的广谱治疗性抗体、疫苗和药物具有重要价值.本研究应用分子模拟技术,采用"典范结构"方法对8H5抗体Fab片段进行结构模建,并通过能量分析、SAS值分析、"拉曼强传图"检验、profile-3D分析等理论验证,获得较为合理的8H5Fab的三维空间结构.8H5Fab与3种HA蛋白晶体结构的分子对接结果表明,8H5抗体与HA蛋白的作用模式与HA宿主来源无关,但与HA结构的亚型相似性相关.综合抗原同源比对结果,推测8H5抗体识别的广谱中和表位是由HA上的Asp68,Asn72,Glu112,Lys113,Ile114,Pro118,Ser120,Tyr137,Tyr252不连续氨基酸残基组成的构象表位.这一模型将为H5亚型禽流感病毒广谱疫苗和治疗性药物的分子设计提供依据

Simulation Research of FAMA Protocol Based on Underwater Acoustic Networks

浅海水声信道的快衰落、长延时给水声网络媒介访问控制(MAC)层协议的设计和性能带来了较大的负面影响.为了提升MAC协议的吞吐量、时延等性能,着重对fAMA(flOOr ACQuISITIOn MulTIPlE ACCESS)协议进行了分析,并以通信网络仿真工具OPnET为仿真平台,得出该协议在吞吐量、时延和能量损耗三方面的性能结果.与目前水声网络主要采用的冲突避免多址接入(MACA)协议的仿真结果相比,fAMA协议能够取得较好的吞吐量和时延性能.Due to the fast fading and long time delay in the shallow water acoustic channels,a large negative influence was brought to the design and performance of medium access control(MAC) layer protocol for underwater acoustic networks.As a result,in order to improve such performances as throughput or end-to-end time delay,this paper focused on the analysis of the floor acquisition multiple access(FAMA) protocol,and through communication network simulation tools-OPNET,results of protocol performances in this simulation experiment such as throughput,delay and energy consumption were obtained.Compared to multiple access collision avoidance(MACA) protocol mainly used in the current underwater acoustic networks,FAMA protocol can get better performances of throughput and time delay.国家自然科学基金(60772141

The design and realization of high precision elecronic scale based on SPCE061A

设计了一款最大测量范围为600g,最小测量分度为0.01g,精度达到六万分之一的高精密电子秤。该电子秤以凌阳16位单片机SPCE061A为核心,Σ-ΔADC为主要称重采集部件;采用了硬件电路抗干扰和软件滤波等技术,以保证整机的精度和稳定性;同时该系统还为用户提供了智能、友好的用户界面和接口。This paper proposes an electronic scale with high precision——the largest measurement range is 600 gram; the minimum equipment division is 0.01 gram. 16 -bit MCU SPCE061A is adopted as the core of the design, and Σ -ΔADC is the most important weighing sample component. Anti -jamming hardware circuit and software filter are used to guarantee the accuracy and stability. The system also provides an intelligent and friendly interface

基于欧拉方法的减阻沟槽壁面湍流涡结构的辨识

基于欧拉方法,使用准则和准则,旨在对减阻沟槽壁面湍流涡结构进行辨识,分析减阻沟槽壁面边界层内瞬时涡结构的分布及演化规律;并采用线性随机估计方法进一步讨论涡包结构的时空统计特征,进而从沟槽对壁面涡结构影响的角度分析其减阻的物理机理

金属离子对白蚁纤维素酶活力的影响

以厦门树白蚁(Glyptotermes XiamenensisLi et Huang)为原料,经PBS缓冲液(pH6.7)抽提、硫酸铵分级分离获得纤维素酶粗提物(简称EGase),经DEAE-Sepharose Fast Flow阴离子交换柱层析、Shephadex G-100凝胶过滤柱层析等纯化,得到电泳单一纯的酶制剂,比活力为458.7 U/mg.研究了金属离子对该酶活力的影响:结果表明,正一价金属离子Li+、Na+、K+对酶活力没有影响,Ca2+、Zn2+和Mn2+有激活作用,重金属离子Cu2+、Pb2+和Hg2+有抑制作用,表现为不可逆抑制