由复映射z←zα+c(α<0)所构造的广义M-集的研究

This paper expounds the escape time algorithm of constructing general Mandelbrot sets from the complex mapping z←z^α+c(α<0). A series of interesting and rich families of fractal images are generated by changing a single parameter α. The fractal images consist of planetary structures with a central planet surrounded by satellite structures. The positions and sizes of the planet and satellite structures are analytically estimated. The embryonic satellite structure arising for non-integer values of α are also analysed. In the end, a few conclusions are reached.     

生物厚靶的He+离子透射能谱

测量了500keV—1MeV的He⁺离子穿过50—90μm厚度的玉米种皮、葡萄果皮和西红柿果皮的透射能谱．结果表明这些生物厚靶是不均匀的,存在着类似于“沟道”的开放通道,沿着这些通道入射离子可以容易地透过靶材料．虽然大多数离子停留在靶中,但一部分透射离子只损失很少的能量．透射能谱显示出一种纯粹的电子阻止特征．30μm厚度样品的透射电子显微镜图谱(TEM)显示150keV的电子可以穿过这些样品得到很清晰的图象．β-1,4葡聚糖是生物种皮或果皮细胞壁的重要的组成部分,计算了该分子链的电子     

ION-BEAM-INDUCED SOLID PHASE CRYSTALLIZATION OF MeV Si+-IMPLANTED Si(100)

The behavior of ion-beam-induced crystallization of a buried amorphous layer created by means of MeV Si⁺ irradiation at 300℃ in Si(100) was studied by Rutherford backscattering and channeling technique. Sohd phase epitaxial crystallizations occurred from both the front and the back amorphous-crystalline(a/c) interfaces with the growth thickness being increased linearly with increasing dose of the annealing ion beam, Nuclear energy deposition was proved to play a dominant role in the process of ion-beam-induced crystallization. The high density of electronic excitation, which could enhance defect production near or at the a/c interface, may thus enhance the nuclearly normalized growth rate of ion-beam-induced crystallization at the front a/c interface.     

基于二维旋转屏的体三维显示系统像素属性分析

介绍了利用视觉暂留效应、高速扫描处于快速旋转中的二维显示屏,从而在三维实空间内再现图像的体三维显示系统.体像素是与三维图像空间内的点对应的图像信息的表述单元,其形状、位置、数目及密度分布等属性,直接影响图像的再现质量和系统的整体性能.对决定体像素属性的屏幕像素尺寸、排列规律及刷新率间的匹配关系进行了建模和量化分析,并从实验上说明了体像素的空间密度分布不均匀时,会导致在显示空间不同位置的同一原始模型有不同的再现效果.     

激光惯性约束聚变靶靶丸制备与表征

激光惯性约束聚变的核心思想是利用球形内爆技术对聚变燃料进行增压,使热核燃料达到高温、高密度的等离子体状态,进而实现聚变点火。基于对称压缩、流体界面不稳定性和实验诊断的考虑,ICF实验对作为热核燃料容器的空心微球的品质在球形度、壁厚均匀性、表面粗糙度以及掺杂水平等方面提出了严格的要求。为满足这些要求,陆续发展了乳液微封装技术、降解芯轴技术、低压等离子体聚合/掺杂技术、干凝胶玻璃微球制备技术等用于多层塑料微球和空心玻璃微球的研制。另一方面,针对ICF靶丸量小、质轻以及表面要求高的特点,发展了相应的非破坏性靶丸参数表征技术,如X光照相技术、4形貌表征技术、微球掺杂水平测量技术以及微球内燃料负载水平快速测试技术。基于这些制备与表征技术,初步实现了多层塑料微球、玻璃微球、聚-??-甲基苯乙烯芯轴微球、梯度掺杂CH微球的研制,满足了神光Ⅱ、神光Ⅲ原型及神光Ⅲ主机上开展的一系列内爆物理实验的要求,同时为未来点火物理实验用靶丸的研制提供了技术支撑。     

Tuning Bandgap of Si-C Heterofullerene-Based Aanotubes by H Adsorption

We theoretically show that H atoms can be chemically adsorbed onto the surface of the Si-C heterofullerene- based nanotubes. The adsorbing energy of the H atom on Si-C heterofullerene-based nanotubes is in the range of 4.28-5.66 eV without any barrier for the H atom to approach to the Si-C heterofullerene-based nanotubes. The band-gap of Si-C heterofullerene-based nanotubes can be dramatically modified by introducing dopant states, i.e., there is a transition from semiconductor to conductor of the Si-C heterofullerene-based nanotubes induced by the adsorption of the H atom. These results actually open a way to tune electronic properties of heterofullerene-based nanotubes and thus may propose an efficient pathway for band structure engineering.     

激光烧蚀高纯Zn形成的微米金属球体对后续脉冲激光的耦合增强效应

脉冲激光束在低真空(约2 Pa)环境下聚焦到高纯Zn靶表面, 烧蚀区域不仅有中心深孔的宏观损伤, 而且还发现大量微米量级的类似足球形状的金属Zn球体结构附着生长在孔洞内侧表面. 实验过程中采用等离子体光谱诊断技术研究宏观和微观损伤对后续脉冲激光的影响程度. 与聚焦于金属Zn平滑表面相比, 宏观损伤可以使后续激光诱导的Zn原子334.5 nm谱线强度提高10.3%, 在此基础上大量Zn微米球体附着在内表面可以使谱线强度再提高34.3%. 因此, 推断这些金属Zn微球表面镶嵌着光洁的纳米量级六边形和五边形小平面, 可以对后续脉冲激光产生镜面反射, 使得激光能量汇聚并耦合增强, 提高烧蚀效率. 实验结果还表明, 这些微米球体的数目随着激光脉冲次数的增加而增多, 使得后续激光能够诱导产生更为致密高温的等离子体. 研究结果有望为激光-金属微孔技术提供新思路. 关键词： 脉冲激光烧蚀 微纳米结构 激光诱导等离子体     

Ab Initio Calculation on Self-Assembled Base-Functionalized Single-Walled Carbon Nanotubes

We perform ab initio calculations on the self-assembled base-functionalized single-walled carbon nanotubes （SWNTs） which exhibit the quasi-1D ‘ladder＇ structure. The optimized configuration in the ab initio calculation is very similar to that obtained from molecular dynamics simulation. We also calculate the electronic structures of the self-assembled base-functionalized SWNTs that exhibit distinct difference from the single-branch base-functionalized SWNT with a localized state lying just below the Fermi level, which may result from the coupling interaction between the bases accompanied by the self-assembly behaviour.     

Hydrogen Storage in Benzene Moiety Decorated Single-Walled Carbon Nanotubes

The hydrogen storage capacity of （5, 5） single-walled carbon nanotubes （SWNTs） decorated chemically with benzene moieties is studied by using molecular dynamics simulations （MDSs） and density functional theory （DFT） calculations. It is found that benzene molecules colliding on （5, 5） SWNTs at incident energy of 50eV form very stable configurations of benzene moiety adsorption on the wall of SWNTs. The MDSs indicate that when the benzene moiety decorated （5, 5） SWNTs and a pristine （5, 5） SWNT are put in a box in which hydrogen molecules are filled to a pressure of ～26 atm, the hydrogen storage capacity of the benzene moiety decorated （5, 5） SWNT is about 4.7wt.% and that of the pristine （5, 5） SWNT is nearly 3.9wt.%.     

非迭代冻结密度近似方法在计算氢键相互作用的合理性研究

为计算相互作用较弱的分子碎片之间的耦合能,Harris从密度泛函理论出发,提出了一种简化方法,即冻结密度近似(FDA)方法.对该方法在描述分子间氢键作用的合理性进行了验证.对水分子间的HO┉H氢键、甲酰胺与水分子间的NH┉O氢键、二氟甲烷和水分子间的OH┉F氢键,以及DNA中的碱基(AT,GC)之间的N—H┉O,N—H┉N等类型的氢键的计算表明:若电子交换关联采用非定域自旋密度近似,FDA的计算结果同其他abinitio方法的计算结果以及实验结果都符合得很好.FDA在计算过程中既不需要求解泊松方程,也不需要进行反复的自洽迭代,所以运算速度较快,在研究生物大分子体系中的氢键相互作用方面具有一定的使用价值 关键词： 冻结密度近似 氢键 密度泛函