基于子波变换的语音信号压缩

基于子波变换的多分辨分析特性 ,直接采用Mallat多层分解的低频系数进行语音信号压缩 ,并进行了计算机仿真 ,结果表明该方法是有效的、可行的 .     

Mechanism of selective separation on the surface of ionic sieve of removal of lead

This note describes a kind of ionic sieve with high selectivity to remove trace lead in water, in which stannic molybdopyrophosphate is used to be the substrate. The mechanism of selective separation on the surface of ionic sieve of removal of lead was explored by analyzing fourier transformation infrared spectra (FTIR), X-ray photoelectron spectrometry (XPS) and the results of selective adsorptivity experiment. The investigation suggests that in the process of synthesizing ionic sieve the olation reactions occur in solid phase by thermodynamic recrystallization and the adsorption units with special selectivity to lead are formed by chemical modification. After the ion exchange for Pb²⁺, the oaltion reactions not only keep the microstructures of adsorption units from collapse, but also provide lead cavties with special selectivity to lead ion that are capable of having special binding “memory effect” to Pb²⁺ by SnO₃ ²⁻ and P₂O₇ ⁴⁻ groups on the surface of this ionic sieve. Meanwhile, the selective separation capacity is a kind of weak chemical effect that is relative to the valence electron state of the adsorbed ion directly and tightly.     

Parameter estimation of sinusoidal signals by using principle of signal matched-phase

A method for estimating frequency, amplitude and phase of a sinusoidal signal is presented based on the principle of signal matched-phase. The formulae for estimating signal parameters are derived, and the algorithm of searching for signal parameters is also given in the case where the signal frequency is unknown. The algorithm is simple and time_saving. The simulation results show that this new method is valid.     

Simulation and evaluation of the quality and availability of typical GLI ocean image

ADEOS-II satellite will be launched in the near future. It collocates many remote sensing instruments in the same platform. Among them, Global Image (GLI) is considered to be a main sensor which will play a key role. In order to understand the characteristics of future GLI ocean color images, a simulation and evaluation of the quality and availability of GLI typical ocean image has been done. In the paper, we first introduce the simulation models briefly, and simulate typical cases of radiance images at visible channels, in which the radiance distribution is based on geographic location, the satellite orbital parameters and sensor properties. A method, complex signal noise ratio (CSNR) to evaluate the image quality and availability, is developed according to the characteristics of image. Meanwhile, a series of CSNR images are generated from the simulated radiance components for different cases, which can be used to evaluate the quality and availability of GLI images before the ADEOS-II is placed in orbit. Finally, the quality and availability of GLI images are quantitatively analyzed by the simulated CSNR data. The results will be beneficial to the people who are in charge of GLI mission or plan to use the data from GLI.     

Characterization of Type p Banach Spaces by the Weak Law of Large Numbers

For weighted sums of the form ∑j＝1anjXnj where {anj, 1≤j≤kn ↑∞,n≥1 } is a real constantarray and {Xnj, 1≤j≤kn ,n≥1 } is a rowwise independent, zero mean, random element array in a real sep-arable Banach space of type p, we establish Lr convergence theorem and.a general weak law of large num-bers respectively, conversely, we characterize Banach spaces of type p in terms of convergence in r-thmean and probability for such weighted sums.     

辊压适张度对圆锯片模态参数的影响

采用实验模态分析的方法 ,研究了在不同适张度情况下圆锯片模态参数的变化规律 ,得到了圆锯片适张度的一种评价依据     

环的半格和与补半格和的弱正则性

给出了环的半格和及补半格和的弱正则性的刻画 ,即若环 R是其弱正则子环 Rα(α∈Γ)的半格和 ,那么 R也是弱正则环 ;若弱正则环 R是其子环 Rα(α∈Γ)的补半格和 ,则 Ra(α∈Γ)都是弱正则环 .     

高频软开关逆变器的控制分析

在50kHz交叉联正激直流环节软开关逆变器工作频率难以提高的基础上，研究了kHz并联正激直流环节软开关逆变器新的控制方案，直流变换器改为20个200kHz正激变换器并联工作，通过一定的控制形成200kHz的直流脉冲电压，逆变器以100kHz的采样频率有限单极性控制，仿真结果表明该控制方案可行，功率管的开关频率提高，开关损耗下降，该方案有助于减小变换器的成本，体积和重量，改善变换器输出特性。     

非线性效应引起的基态孤子啁啾特性

理论上分析了自相位调制 (SPM)引起的基态孤子啁啾的传输特性 ,讨论了初始啁啾对基态孤子啁啾特性的影响