串联型罗仑兹混沌遮掩保密通信电路

设计了一种串联型罗仑兹混沌数字信号保密通信电路系统.该系统利用串联同步罗仑兹混沌电路进行信号混沌遮掩保密通信,在发送端和接收端之间只需传送一个叠加有传送信息的混沌信号即可实现高质量保密传送信息.模拟实验表明,在一定条件下传送数字信号时接收端可无失真地恢复所传信号.     

基于掩蔽阈值与复倒谱的数字音频水印算法

文中介绍了掩蔽效应与复倒谱技术,并根据这两种技术的特点,提出了一种基于掩蔽阈值与复倒谱技术相结合的数字音频水印算法,并给出了最终的实验结果与结果分析。     

In-Stream Masking of Aluminium in the Determination of Fluoride by Flow-Injection Potentiometry

Abstract

The ability of selected complexing agents to mask aluminium and release fluoride for potentiometric determination in-stream has been assessed. The experimental manifold incorporated a cascade flow cell and comprised two flow paths, the first for conventional flow-injection and the second enabling stopped-flow analyses to be performed. For solutions containing equimolar quantities of Al and F at concentrations up to 10^?3 M in each ion, better than 90% fluoride recovery was achieved in 16s using Tiron. At higher aluminium loadings, fluoride was released more slowly, with citrate and DCTA being found to be more efficient than Tiron. At an Al. F ratio of 4:1 (10^?3 M F), relative release rates for fluoride over a 10 minute period occurred in the following order:

citrate > DCTA > Tiron > tartrate > EDTA

Acetate and hexamine buffers, often recommended as components in TISAB formulations, were as effective as EDTA in releasing fluoride. Using an acetate buffer with citrate as the decomplexing agent slowed this release. Aged Al/F solutions responded almost as quickly as fresh solutions to Tiron and DCTA, with small pH-related effects being observed for solutions 20 days old.     

Masking Ability of Various Complexing Agents for Aluminum in the Fluorine Determination with a Fluoride Ion-Selective Electrode

Abstract

In the determination of fluoride ion with a fluoride ion-selective electrode, tiron is the most effective of masking agents tested for aluminum. The higher the pH, the more effective the masking, but the hydroxide ion raises the lower limit of determinable fluoride ion concentration at higher pH.

Therefore, measurements at pH 6.0 are preferable. Fluorine in two glass samples has been successfully determined with tiron.     

Intratympanic manganese administration revealed sound intensity and frequency dependent functional activity in rat auditory pathway

The cochlear plays a vital role in the sense and sensitivity of hearing; however, there is currently a lack of knowledge regarding the relationships between mechanical transduction of sound at different intensities and frequencies in the cochlear and the neurochemical processes that lead to neuronal responses in the central auditory system. In the current study, we introduced manganese-enhanced MRI (MEMRI), a convenient in vivo imaging method, for investigation of how sound, at different intensities and frequencies, is propagated from the cochlear to the central auditory system. Using MEMRI with intratympanic administration, we demonstrated differential manganese signal enhancements according to sound intensity and frequencies in the ascending auditory pathway of the rat after administration ofintratympanicMnCl₂.Compared to signal enhancement without explicit sound stimuli, auditory structures in the ascending auditory pathway showed stronger signal enhancement in rats who received sound stimuli of 10 and 40 kHz. In addition, signal enhancement with a stimulation frequency of 40 kHz was stronger than that with 10 kHz. Therefore, the results of this study seem to suggest that, in order to achieve an effective response to high sound intensity or frequency, more firing of auditory neurons, or firing of many auditory neurons together for the pooled neural activity is needed.     

混响感知的听觉心理

综述了中国传媒大学传播声学研究所近年来在混响的主观感知机理上的研究工作和进展,涉及混响感的语意调查与分析,音乐听闻的混响偏爱度实验,混响感的差别阈限,混响感的因素分析,以及混响处理与音乐情感之间的相互影响等研究结果。对混响感知的研究对进一步探究在有界空间中主观听感的生理心理机制是十分有启发的。     

静压桩沉桩及已打入桩遮拦效应的数值模拟

采用三维有限差分软件 FLAC3D 建立了数值模型, 对比了圆孔扩张理论的解析解与数值解, 并在此基础上建立了桩实体单元基于位移贯入法模拟桩-土间摩擦作用, 且与相关文献中施加节点力模拟摩擦效应的方法进行了对比, 二者的计算结果较吻合. 基于此数值模拟方法 对静压桩单桩、双桩的沉桩过程进行计算分析, 并就已打入桩体对沉桩过程中土体位移的影响 进行研究, 得到以下结论: 模拟桩-土问摩擦效应的两种方法中, 位移贯入法计算所得土体水平位移在地表处较大, 这是因为桩体以固定速度向下运动时, 为阻止圆孔缩径而约束了其径向位移, 消除了摩擦效应对土体水平作用的影响. 沉桩结束后, 在大于地表下1/4 桩长深度范围内 的土体水平位移较大, 是主要的变形区域. 上部土体沉降较大, 而下部土体沉降较小, 其中距地 表下1/8 桩长至 1/4 桩长处沉降最大, 说明已打入桩的存在改变了土体水平位移的大小, 更使得土体水平位移随深度的变化趋于线性. 待打入桩的沉桩过程使得已打入桩身产生一定的倾斜. 由于沉桩扩孔的影响, 受到水平挤压的桩前土体在已打入桩的阻隔下沿着桩身向上隆起, 表明已打入桩的存在改变了土体位移的分布模式, 最终达到了减小水平位移的目的.      

基于听觉谱特征的变压器绕组状态检测研究

绕组松动是变压器常见故障之一,对变压器的安全运行产生巨大威胁.故对其进行精准的监测,对提高电力系统的安全稳定性具有十分重要的意义.基于声信号的变压器绕组松动检测,由于其具有无损检测和不需停运变压器等优点,成为近年来研究的热点.但声信号检测存在故障特征提前复杂和易受噪声干扰等缺陷,限制了其工程应用.该文提出了一种基于声信...     

HDTV音频解码系统算法优化及实现

Dolby AC-3是杜比实验室的第三代感知音频编解码系统,将心理声学模型溶入其中,大大地提高了编解码性能.本文介绍了Dolby AC-3音频标准解码算法的基本原理,并通过C程序实现该解码算法.详细推导了用两个N/4点的DCT-II来实现N点的改进离散余弦反变换(IMDCT)解码单元的优化算法,将此AC-3解码算法进行仿真试验,对仿真结果进行主客观评价.评价结果显示解码速度得到提高,为AC-3解码器的实时实现奠定了基础.