Auditory place theory and frequency difference limen

It has been a barrier that the place code is far too coarse a mechanism to account for the finest frequency difference limen for place theory of hearing since it was proposed in 19th century. A place correlation model, which takes the energy distribution of a pure tone in neighboring bands of auditory filters into full account, was presented in this paper. The model based on the place theory and some experimental results of the psychophysical tuning curves of hearing can explain the finest difference limen for frequency (about 0.02 or 0.3% at 1000 Hz) easily. Using a standard 1/3 octave filter bank of which the relationship between the frequency of a input pure tone apart from the centre frequency of K-th filter band, Δf, and the output intensity difference between K-th and (K l)-th filters,ΔE, was established in order to show the fine frequency detection ability of the filter bank. This model can also be used to abstract the fundamental frequency of speech and to measure the frequency of pure tone precisely.     

美国伦斯勒理工学院招生信息

带电粒子在一个均匀磁场中的回旋频率为qB/m ,其中q和m是粒子的电荷与质量 ,B是磁感应强度 .这一关系式是使用离子回旋共振质谱仪进行分子质量对比的基础 ,其应用范围涵盖了鉴别生物分子、研究化学反应速率直到确定原子光谱的精细结构常数 .美国麻省理工学院 (MIT)的物理学家Da     

磁放大器原理及执行器故障分析

论述了磁放大器的工作原理和特点 ,介绍了磁放大器在执行器中的应用 ,对执行器的两种常见故障作了分析     

一种短波电台频率合成器的研制

该文介绍一种采用Ｍｏｔｏｒｏｌａ公司ＭＣ１４５１４６和ＭＣ１２０１７／１８蕊片构成的短波电台频率合成器的硬件电路实现方案。频率合成器的输出频率范围２～２９．９９９９ＭＨｚ，频率间隔１００Ｈｚ，换频时间小于０．０１ｓ。文中论述了这种多环数字式频率合成器工作原理，各环路之间对应的频率关系和电路参数的选择，给出了频率合成器的试验结果．     

钢丝绳动参数的新检测方法研究

本文研究了一种新的非接触式的钢丝绳运动速度，运行距离及所受张力的检测方法；分析了检测系统各组成部分的工作原理和检测信号的处理过程。提出了在实测过程中应注意的问题和应进一步开展的研究工作     

部分真值表在环形分配器设计中的应用

目前步进电机以五相居多，硬件环形分配器用卡罗图来进行设计，则显得复杂冗赘，如果从步进电机运行的规律中找出约束条件，建立部分真值表，便可以直接写出控制逻辑函数，这对于设计相数、拍数较多的步进电机的环形分配器极为方便，这种设计思路在进行数字电路工程设计中也是可以值得借鉴的。     

Discovering Frequent Subtrees from XML Data Using Neural Networks

By rapid progress of network and storage technologies, a huge amount of electronic data such as Web pages and XML has been available on Internet. In this paper, we study a data-mining problem of discovering frequent ordered sub-trees in a large collection of XML data, where both of the patterns and the data are modeled by labeled ordered trees. We present an efficient algorithm of Ordered Subtree Miner （OSTMiner） based on two- layer neural networks with Hebb rule, that computes all ordered sub-trees appearing in a collection of XML trees with frequent above a user-specified threshold using a special structure EM-tree. In this algo- rithm, EM-tree is used as an extended merging tree to supply scheme information for efficient pruning and mining frequent sub-trees. Experiments results showed that OSTMiner has good response time and scales well.     

Ohmic Radio-Frequency Synergy Current Drive and Transformer Recharging Experiments in the HT-7 Tokamak

Lower hybrid current drive (LHCD) experiments for investigating the interaction between lower hybrid (LH) wave and residual dc electric field were performed in extensive plasma parameter ranges in the HT-7 superconducting tokamak. The experimental results are well fitted to the Karney-Fisch theory on the efficiency of LH waves energy converted to poloidal magnetic field energy. The fraction of absorbed LH power is about 0.75 for the HT-7 machine, and the upshift of the LH-wave parallel refraction index during LHCD experiments have been derived by the optimizing fitting parameters. The LH wave is also used for the transformer recharging when the plasma current is maintained unchanged. The highest efficiency about 7% has been achieved in HT-7 machine.     

一类信号所确定的预测误差滤波器的零点分布

对R.Kumaresan提出的由M个指数衰减(或不衰减)的正弦信号的和组成的信号进行了推广,讨论了由这类推广了的信号所确定的预测误差滤波器多项式的零点分布。信号零点完全由信号所确定。不论信号零点如何分布,只要预测误差滤波器多项式的系数满足某些条件,则其额外零点在单位圆的外部呈均匀状分布。