非线性抛物型偏积分微分方程的H1-Galerkin 混合有限元方法

收稿给出一类非线性抛物型偏积分微分方程的H1-Galerkin混合有限元方法.给出了一维空间的半离散、全离散格式及最优阶误差估计,并将该方法推广到二维和三维空间.     

Theoretical study of thermoelectronic laser energy conversion: II. Characteristics of optical discharge

The dependences of the parameters of a continuous optical discharge in an interelectrode space of a thermoelectronic laser energy converter on the gas pressure, electron emission current, and discharge current are studied. The current-voltage characteristics of the discharge are calculated.     

A Study of the Dynamics of Formation of Plasmoids in the Gatchina Discharge

Technical Physics - The results of studies of the Gatchina discharge conducted at the Harbin University of Technology (China) have been presented. The Gatchina discharge is mainly used to create an...     

Sparse asymptotic minimum variance based bearing estimation algorithm for a single vector hydrophone

For underwater target detection using a single vector hydrophone, sparse asymptotic minimum variance(SAMV) method is used to estimate the target bearing. The SAMV discretizes the entire scanning space and the target bearing is located at the position of the discrete direction. The SAMV algorithm utilizes the sparsity of the spatial signal to improve the estimation performance of the target bearing. Background noise level(BNL) of the bearing estimation of SAMV algorithm is lower than those of the conventional beam forming(CBF)method and minimum variance distortionless response(MVDR) method for different signal noise ratios(SNRs). When the SNR is higher than 0 d B, the direction-finding error of this algorithm is less than 2°. Moreover, the SAMV algorithm has a better dimensional orientation resolution capability. The experimental results show that the SAMV algorithm gives a bearing and time recording map with a lower BNL, which effectively verifies the effectiveness of SAMV algorithm in terms of underwater target detection.     

离子交换色谱法分离测定磷霉素的研究

分别采用全多孔型硅胶基键合强阴离子交换柱与氨丙基键合硅胶柱,在低波长 ２００ ｎｍ 处检测,分离测定了磷霉素 探讨了流动相条件,如ｐ Ｈ 值、离子强度等对磷霉素保留及分离选择性的影响,优化分离条件,建立了一种测定磷霉素的高效液相色谱新方法方法简便、快速     

交通流非参数回归模型

交通流宏观参数流量、速度和占有率在交通工程和管理中具有非常重要的作用 ,对这三者关系的刻划反映了道路本身特性和交通流的规律。到目前为止 ,基本上采用线性或非线性的参数模型来描述 ,此类模型在应用中具有一定的局限性 ,并交通变量时间序列进行预测 ,数据拟合表明 ,选择适当的核函数或邻近数以及窗宽 ,可以达到比较满意的效果     

Synthesis of nanosized titanium dioxide from tetrabutoxytitanium

Mesoporous TiO₂ has been obtained by template synthesis. The introduction of a surfactant in the hydrolysis of tetrabutoxytitanium in aqueous ethanol allows the structure of the resulting material to be controlled. The amorphous TiO₂ resulting from hydrolysis turns into anatase on being calcined at 300°C. As determined by X-ray diffraction, the anatase crystallite size is 70 nm in the presence of the highest surfactant concentration examined and 210 nm in the absence of a surfactant. Amorphous materials have been characterized by electron microscopy and differential thermal analysis. The ultimate benzene adsorption value has been determined for calcined mesoporous TiO₂.     

Waveform control of orientation-dependent ionization of DCl in few-cycle laser fields

Strong few-cycle light fields with stable electric field waveforms allow controlling electrons on time scales down to the attosecond domain. We have studied the dissociative ionization of randomly oriented DCl in 5 fs light fields at 720 nm in the tunneling regime. Momentum distributions of D(+) and Cl(+) fragments were recorded via velocity-map imaging. A waveform-dependent anti-correlated directional emission of D(+) and Cl(+) fragments is observed. Comparison of our results with calculations indicates that tailoring of the light field via the carrier envelope phase permits the control over the orientation of DCl(+) and in turn the directional emission of charged fragments upon the breakup of the molecular ion.     

频率自适应最优权重阵列干涉条纹处理技术

考虑长基线水平阵列波束形成对声场模态呈现的滤波特征,建立了一种随频率改变滤波通带的阵列权矢量设计方法。基于简正波理论,结合声场波束形成特点,在分析了常规波束形成信号LOFAR谱图干涉条纹的清晰度和条纹结构不同于单水听器输出信号条纹现象基础上,采用线性等式约束的二次优化模型,给出了一种频率自适应的最优权重估计。数值仿真验证和试验数据分析表明,利用该方法设计的最优权重阵列波束处理,可以滤波出SRBR(Surface-Reflected Bottom-Reflected)或N-SRBR(Non-Surface-Reflected Bottom-Reflected)模态组成的波束形成信号,信号谱图干涉条纹斜率与理论分析基本一致。