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41.
本文论述了在信号与系统分析中如何利用MATLAB软件编程使一些运算量较大、抽象的问题变得简单而直观。 相似文献
42.
XIE Bosun 《声学学报:英文版》2006,25(4):330-341
From the point of spatial sampling, spatial interpolation of HRTFs (head-related transfer functions) and signal mixing for multichannel (surround) sound are analyzed. First, it is proved that they are mathematically equivalent. Different methods for HRTFs interpolation are equivalent to different signal mixing methods for multichannel sound. Then, a stricter derivation for the signal mixing of multichannel sound and the law of sine for stereophonic sound is given. It is pointed out that trying to reconstruct lateral HRTFs by adjacent linear interpolation is wrong. And for accurate sound image localization, the conventional equation of adjacent linear interpolation of HRTFs is revised. At last, it is also pointed out that some methods used in the analysis of HRTFs and multichannel sound can be used for reference mutually. 相似文献
43.
Md. Naziruddin Khan A. S. AI-Dwayyan Z. H. Zaidi 《中国物理快报》2006,23(9):2407-2410
Chrysene and 1.2-benzanthracene are successfully doped in a solid wax film and their vibrational spectra in gooo--400cm^-1 are discussed. The harmonic frequencies and relative intensities of both the molecules observed in the film are compared with theoretical values calculated by the density functional theory (DFT) model as well as with the previous experimental data. The effects on spectra due to change of matrix and some additional bands observed in the wax film are also reported. Excellent agreement in the spectral positions and strengths between the experiments and DFT values are found. 相似文献
44.
QAM中频调制的实现方案及其比较 总被引:1,自引:0,他引:1
正交幅度调制(QAM)在ISDN、ADSL、LDMS、有线电视网络的Cable Modem以及无线广播数字电视等多种宽带接入方式中得到广泛应用。QAM须经过数字调制、矢量调制、中频调制的过程,其中中频调制是将I、Q数字基带信号转换为射频信号的关键环节。本文提出模拟和数字两种实现QAM中频调制的方案,然后对它们进行比较。 相似文献
45.
46.
An erbium-doped phosphate glass fibre has been drawn by the rod-in-tube technique in our laboratory. The gain for the Er^3+-doped phosphate glass fibre with different pump powers and with different input signal wavelengths is investigated. The 2.2-cm-long fibre, pumped by a single-mode 980-nm fibre-pigtailed laser diode, can provide a net gain per unit length greater than 1.SdB/cm. The pump threshold is about 50mW at the wavelength of 1534nm, and below 70roW at 1550nm. The gain linewidth of the Er^3+-doped phosphate glass fibre is greater than 34 nm and can cover the C band in optical communication networks. 相似文献
47.
48.
利用对德拜模式密度的修正入手,重新讨论了频率函数的热容量,得到了在高、低温极限与实验相符合的结论,该模型保留了德拜模型的优点,又对其不足之外进行了修正,同时给出了修正项的来源。 相似文献
49.
Application of Electron-Shelving Detection via 423 nm Transition in Calcium-Beam Optical Frequency Standard
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A new scheme of small compact optical frequency standard based on thermal calcium beam with application of 423 nm shelving detection and sharp-angle velocity selection detection is proposed. Combining these presented techniques, we conclude that a small compact optical frequency standard based on thermal calcium beam will outperform the commercial caesium-beam microwave dock, like the 5071 Cs clock (from Hp to Agilent, now Symmetricom company), both in accuracy and stability. 相似文献
50.
By numerical simulations on frequency dependence of the spiking threshold, i.e. on the critical amplitude of periodic stimulus, for a neuron to fire, we find that bushy cells in the cochlear nuclear exhibit frequency selec- tivity behaviour. However, the selective frequency band of a bushy cell is far away from that of the preferred spectral range in human and mammal auditory perception. The mechanism underlying this neural activity is also discussed. Further studies show that the ion channel densities have little impact on the selective frequency band of bushy cells. These findings suggest that the neuronal behaviour of frequency selectivity in bushy cells at both the single cell and population levels may be not functionally relevant to frequency discrimination. Our results may reveal a neural hint to the reconsideration on the busily cell functional role in auditory information processing of sound frequency. 相似文献