幅相联合处理算法的分析和实时实现

针对多种接收相参处理法对改善因子的限制 ,提出了一种全新的幅相联合处理算法。介绍了该算法的数学分析 ,计算仿真 ,数字信号处理器 (DSP)实时实现方法。该算法分别通过卷积和相关提取不受发射脉冲随机初相、振幅、脉间频率抖动影响的幅度分量和相位分量 ,再联合成新的相参复信号。这个联合信号具有幅度、相位时间一致性好 ,便于用DSP实时实现的优点。理论分析和实际测试表明 :该算法的改善因子性能大于 5 5 d B。该算法的应用使某非相参雷达的杂波中可见度性能提高 10 d B     

影响课堂计算机辅助教学效果的因素分析

随着计算机技术和网络技术对教育教学的深入影响,计算机逐步进入课堂,计算机辅助教学得到了空前发展。课堂计算机辅助教学是信息技术应用于教育的核心,是我国大中小学计算机辅助教育的应用重点。当前课堂计算机辅助教学仍处于研究和探索阶段,课堂计算机辅助教学受到软件、教师、环境、学生等因素的制约,其教学效果没有充分发挥出来。本文主要探讨影响课堂计算机辅助教学效果的诸多因素,分析当前课堂计算机辅助教学的认识和实践误区,从而有效地控制各因素的影响,提高课堂计算机辅助教学效果。     

生物学网络信号教学模式的构建

通过对理论依据、制作方法、教学程序、教学评价、注意事项等方面的阐述，介绍一种以心理学教学论知识为基础，充分体现学生自主学习，融科学性、逻辑性、直观性、趣味性为一体的生物学教学模式。     

一种基于HVS模型的图像质量信噪比评价方法

从研究人体视觉系统的角度出发,给出了一种基于人体视觉系统HVS模型的客观图像质量评价方法,提出了基于HVS模型的SNR和PSNR评价标准,并给出了对典型图像的评测结果,同时也验证了与主观评价结果的一致性。     

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.     

Phase transition , structure and shape memory effect of Ni47Ti43Hf10 alloy

A Ni₄₇Ti₄₃Hf₁₀ high temperature shape memory alloy is fabricated. The martensitic transformation temperature (TT) is obtained by differential scanning calorimetry and four-probe electrical resistivity measurements. The effect of thermal cycling is investigated and it is found that the TT tends to be stable quickly, which is of benefit to practical applications. The martensite structure is determined to be B19' monoclinic by X-ray diffraction and transmission electron microscopy. One-way and two-way (which is seldom reported before) shape memory properties are studied by tensile and bending tests. The cycling number of two-way shape memory effect is tested for more than 20000 times.