Phase-modulation effects in degenerate four-wave-mixing

Received: 14 August 1997     

Two New Secoiridoid Glycosides from Tripterospermum chinense

Two new secoiridoid glycosides, tripterospermumcin A ( 1 ) and B ( 2 ), were isolated from the EtOH extract of the aerial parts of Tripterospermum chinense (Migo ) H. Smith , along with three known compounds, secologanin, secologanol, and sweroside. Their structures were established on the basis of UV, IR, MS, and extensive 1D‐ and 2D‐NMR analyses, as well as by literature comparison of spectroscopic data.     

Fractal range of a 3-point ternary interpolatory subdivision scheme with two parameters

In this paper, we analyze the fractal property of Hassan’s 3-point ternary interpolatory subdivision scheme with two parameters. The fractal range of the scheme is obtained and illustrated. Many examples show that the obtained results suggest a clear direction to generate fractal curves and surfaces by using this scheme.     

高速粒子场同轴Fraunhofer全息数据处理系统研究

介绍了用同轴Fraunhofer全息测量强动载下材料表面微喷射粒子场的数据处理方法.在全息像重建过程中，将再现的三维粒子场由计算机控制分成许多小薄层采集.在数据处理过程中根据图像中粒子边缘，决定在整幅图或局部采用边缘检测的方法提取大粒子，根据图像的灰度分布将图像分成很多小区域，在每个小区域采用不同的阈值分割图像.在处理结果的校正中根据粒子场的特点，去除过大、过小和重复统计粒子.采用该方法得到了粒子的空间分布图像及粒子大小的统计结果.     

氧化物表面的侧表面原子成象——Ⅰ.Eu_2O_2晶体由位错滑移形成表面台阶的动态原位观察

通过高分辨电子显微术获得了Eu_2O_3晶体分子清洁的表面侧面原子成象,观察到了由表面附近位错滑移出表面而形成表面原子台阶的动态变化过程,同时还观察到了此种表面台阶的形核生长。     

Mössbauer effect in f.c.c. Fe-Ni-C alloys after the ultrasonic impact surface treatment

M?ssbauer spectroscopy was used for study of the f.c.c. Fe-30.5%Ni-1.5%C, Fe-30.0%Ni-1.3%C, Fe-30.1%Ni-0.44%Mn-1.22%C, Fe-30.3%Ni alloys after the heat treatment at 1373 K in vacuum and the impact ultrasonic surface treatment in vacuum. The vibration amplitude of the magnetostrictor-wave guide-sample system on the (1–3)kHz frequencies was 20 μm and 28 μm corresponding to the power of impacts of 2.4 and 4.7 J/s. In order to show the redistribution process of carbon under the treatment, the ageing of the Fe-30.0%Ni-1.3%C alloy was carried out at 773 K in vacuum. As shown, the ultrasonics of smaller power does not result in distinctive changes in the hyperfine magnetic structure and solid solution state. The increase of power of impacts does not change the phase composition of the alloys except the atomic redistribution in a solid solution varying the electron spin and charge densities on iron nuclei. The results were analyzed in comparison with the data derived after the low-frequency impact surface treatment. Presented at International Colloquium “M?ssbauer Spectroscopy in Materials Science”, Všemina, Czech Republic, June 1–4, 2004. The Science and Technology Center in Ukraine (project #2412) and partially budget program supported this work.     

Applying the finite-thickness model to designs of cylindrical microlenses with small -numbers

The finite-thickness model (FTM) is applied to the design of cylindrical microlenses based on the wave-front interference principle, rather than the existing zero-thickness model (ZTM). This design method is very simple in physics and highly efficient in computations. For cylindrical lenses with different f-numbers (from f/1.5 to f/0.6), the detailed designs by using both the FTM and the ZTM are carried out. To show the superiority of the FTM to the ZTM, we investigate the focal performance of all the designed lenses based on rigorous electromagnetic theory and the boundary element method. Numerical results reveal that the constructed cylindrical lenses by the FTM are witnessed to exhibit much better focusing performance than those by the ZTM, especially for the small f-numbers.     

Microwave-assisted synthesis and electrochemical capacitance of polyaniline/multi-wall carbon nanotubes composite

Polyaniline/multi-wall carbon nanotubes composite (PANI/MWNTs) was rapidly synthesized by microwave-assisted polymerization. Transmission electron microscope (TEM) image revealed that this composite was a core–shell structure with PANI layers (50–70 nm). Electrochemical behavior of the composite was evaluated by cyclic voltammetry (CV) and galvanostatic charge–discharge tests with a two-electrode system. An enhanced specific capacitance of 322 F/g with a specific energy density of 22 W h/kg was about 12 times that of MWNTs. This composite also exhibited a good rate capability, retaining up to 87% of initial capacity at a current density of 5 mA/cm².     

Excitation of a periodic cylindrical microstrip <Emphasis Type="Italic">N</Emphasis>-element antenna array

We consider the problem of excitation of a periodic cylindrical microstrip antenna array which consists of N elements placed periodically in the azimuthal plane on the surface of a dielectric substrate. Each element is an array of M patches having the rectangular-cylindrical shape. Each patch is fed by a rod which is approximately modeled by a charged filament of finite length. An integral equation for the surface current on the patches is formulated and solved by the method of moments in the spatial domain. Far-field patterns of the antenna are calculated for different values of N and M at the resonant frequencies. It is shown that a two-frequency N-lobe antenna having two different far-field patterns at two different resonant frequencies can be developed. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 2, pp. 134–146, February 2007.     

稳态条件下气溶胶粒子在口腔模型中的沉淀率

以实际人体解剖学数据为基础,利用流体力学软件构建了口腔模型。由于口腔形状不规则,流场中会有湍流产生,所以本文选用的是k-ω方程。在此基础上,假设吸入空气流量为一个常量,改变吸入气体、气溶胶粒子的物理参数,以调整St数的变化,模拟不同情况下气溶胶粒子运动情况。由模拟结果可知:气溶胶粒子在口腔中的沉淀率受粒子半径、密度、及流速的影响,并随这些量的增加而增加;沉淀率可以视作St数的函数,并随St数的增加而增加;气溶胶粒子在口腔中的沉淀分布受模型几何形状和湍流的影响,在喉部附近沉淀较为明显;粒子在口腔中将沿怎样的轨迹运动则取决于粒子在入口处的初始位置。