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231.
基于MDA法计算水雾粒子红外隐身粒径 总被引:1,自引:0,他引:1
水雾隐身技术是一种较为理想且经济适用的目标特征信号控制技术。本文从辐射传输方程出发,考虑水雾粒子的本身辐射和散射,提出以红外表观透射率评价水雾粒子的红外隐身性能。应用Modified Differential Approximation(MDA)法结合MIE理论,计算了水雾粒子红外表观透射率随水雾粒子浓度和粒径的变化关系,得到水雾粒子最佳红外隐身粒径。结果表明:水雾粒子的红外表观透射率随粒子浓度的增加而减小,但当粒子的浓度增加到一定值时,红外表观透射率基本保持不变;水雾粒子的红外表观透射率随粒径的增加先减小后增大,当探测波段为3~5μm时,水雾粒子的最佳红外隐身粒径为6μm;而探测波段为8~12μm时,水雾粒子的最佳红外隐身粒径为12μm。 相似文献
232.
We derive the motion equations and the structure equations of neutral and charged test particles, starting from the gravitational field equations. The method consists in the application of conservation laws to singular tensor densities, which represent regions of strong matter concentration. Moreover, a Hamiltonian formulation of the particle equations is given, in the form of implicit differential equations generated by Hamiltonian Morse families. 相似文献
233.
本文报道了锌、镉、汞、铅硫化物半导体极超微粒子的制备以及它们的光谱性质,比较了它们的粗、细粒子的吸收光谱和荧光光谱的差异,用量子化粒径效应解释了当超微粒子的粒径减小时出现的能级分裂.同时讨论了上述物质的极超微粒子在老化过程中的行为及其原因. 相似文献
234.
235.
通过自由基无规共聚和酰化反应两步法制备了两类侧链含丙烯酸酯双键的含氟低聚物,并通过调节反应物种类、配比和链转移剂用量,制备出一系列不同双键含量、氟含量的多官能度低聚物。以制备的含氟低聚物为原料,进行超临界二氧化碳光聚合制粒。聚合得到的含氟颗粒作为增强相,加入TPGDA光固化配方中,可实现颗粒与树脂的化学交联,显著提高基材的交联密度,改善疏水性,降低吸水率,并增强热稳定性。 相似文献
236.
Janus 粒子,也称为阴阳结构粒子或两面性非对称粒子,是指表面上具有两种或两种以上不同化学组成或性质的不对称粒子。目前,Janus 粒子因其独特的结构和功能已经逐渐成为生物医药、催化、材料以及防污等领域中的新型功能材料。在环境检测领域,Janus材料亦因其特殊的光学、磁学及电学性能,为提高检测灵敏度、选择性和稳定性等提供了新的研究方向。基于此,本文主要讨论了Janus材料在环境检测方面的特点、优势和相关应用。最后,本文基于本课题组的研究经验以及工作中所面临的问题,对本领域的发展和未来的研究方向提出了展望,以期对本领域的未来发展提供指导。 相似文献
237.
Mukhtar Ahmed Rana 《Radiation measurements》2012,47(1):50-56
Systematic measurements of swelling of CR-39 nuclear track detector (NTD) due to irradiation with fission fragments and alpha particles over a wide range of fluences from 252Cf are presented here. Precisely designed and optimized exposure and chemical etching experiments were employed to unfold the structure of radiation induced surface damage. Delays in the startup of the chemical etching of latent tracks in low radiation fluence detectors are measured and are found to contain important information about structure of the surface damage. Simple atomic scale pictures of radiation induced surface damage and its chemical etching are developed using measurements of radiation induced swelling of CR-39 detectors and nuclear track parameters. The computer code SRIM2010 was utilized for the calculations of basic features of latent tracks of fission fragments and alpha particles in CR-39. Another computer code TRACK_VISION was used to compute parameters of etched tracks. Computations and experimental findings in the paper coherently compose a realistic picture of radiation damage. 相似文献
238.
Norio Yoshino Munetoshi Morita Atsushi Ito Masahiko Abe 《Journal of fluorine chemistry》1995,70(2):187-191
Anionic surfactants having two polyfluoroalkyl chains per molecule, i.e. the sodium salt of bis(1H, 1H, 2H,2H-heptadeca-fluorodecyl)-2-sulfosuccinate, CF3(CF2)7(CH2)2OCOCH2CH(SO3Na)COO(CH2)2(CF2)7CF3, the sodium salt of bis(1H, 1H, 2H, 2H-tridecafluoro-octyl)-2-sulfosuccinate, CF3(CF2)5(CH2)2OCOCH2CH(SO3Na)COO(CH2)2(CF2)5CF3, and the sodium salt of bis(1H, 1H, 2H, 2H-nonafluorohexyl)-2-sulfosuccinate, CF3(CF2)3(CH2)2OCOCH2CH(SO3Na)COO(CH2)2(CF2)3CF3, have been prepared from maleic anhydride, the corresponding alcohols possessing a polyfluoroalkyl chain and sodium hydrogen sulfite. The flocculation and redispersion abilities of these surfactants for dispersed magnetic particles in water have been examined to investigate the effect of the chain length. It was found that this ability was enhanced by an increase in the chain length. The contact angles for water for pelleted surface-modified magnetite have been measured. In order to compare this ability and the contact angles, data for other fluorinated surfactant have been obtained. The Kraff point, the surface tension and the pNa of the aqueous surfactant solutions have also been measured. 相似文献
239.
An analytical method for the determination of plutonium concentration and its isotope ratio (240Pu/239Pu) for settling particle samples by inductively coupled plasma mass spectrometry (ICP-MS) is presented. The generally used approach for Pu preconcentration by increasing the amount of samples is not applicable because of the small size of settling particle samples available for the analysis for Pu isotopes. Efforts were made to improve the sensitivity of a sector-field ICP-MS (SF-ICP-MS) and reduce the 238UH+ interference for Pu analysis by combining a high-efficiency sample introduction system (APEX-Q). An extremely low detection limit of 0.07 fg Pu was achieved, which allowed the determination of Pu isotope ratio at femtogram levels. The precision and accuracy of 240Pu/239Pu isotope ratio analysis were carefully examined with a certified Pu isotope standard (NBS-947) and an ocean sediment reference material (IAEA-368). Simple anion-exchange chromatography for the separation and purification of Pu was combined with the APEX-Q/SF-ICP-MS system to determine Pu isotopes in settling particles collected in the East China Sea continental margin. The obtained results supported a previous observation on the lateral transport of Pu containing particles in this continental margin. 相似文献
240.
Genlin Sun Jeong Soo Kim Yune Sung Kim Hyun Joo An Won Jo Cheong 《Journal of separation science》2019,42(16):2612-2620
A stationary phase was prepared by chemical derivatization of the support particles with a layer of copolymer composed of styrene and N‐phenyl acrylamide. Silica monolith particles of ca. 2.6 µm (volume‐based average) have been prepared as the support particles by sol‐gel reaction followed by differential sedimentation. The particles were reacted with 3‐chloropropyl trimethoxysilane followed by sodium diethyldithiocarbamate to introduce an initiator moiety. Then, the copolymer layer was immobilized via reversible addition‐fragmentation transfer polymerization. The resultant phase was packed in glass‐lined stainless‐steel micro‐columns (1 x 150 mm) and evaluated for the separation of a mixture composed of five peptides (Trp‐Gly, Thr‐Tyr‐Ser, angiotensin I, isotocin and bradykinin). The effect of monomer mixing ratio (styrene versus N‐phenyl acrylamide) on the chromatographic separation efficiency of the stationary phase was examined. A number of theoretical plates (N) as high as 33 600 plates/column (224 000 plates/m, 4.46 µm plate height) was achieved using the column packed with the optimized stationary phase. The column‐to‐column reproducibility based on three columns packed with three different batches of stationary phase was found satisfactory in separation efficiency, retention factor, and asymmetry factor. 相似文献