排序方式: 共有102条查询结果,搜索用时 15 毫秒
31.
This paper considers a two-phase free boundary problem for coupled system including one parabolic equation and two elliptic equations. The problem comes from the discussion of a growth model of self-lnaintaining protocell in multidimensional case. The local classical solution of the problem with free boundary F : y = g(x,t) between two domains is being seeked. The local existence and uniqueness of the problem will be proved in multidimensional case. 相似文献
32.
We demonstrate experimentally the application of a phase error detection method in the coherent beam combination (CBC) of a laser array. The method is based on the Hartmann micro-lens array. Both the piston and tilt errors can be detected and corrected simultaneously by combining this method with adaptive optics-correcting technology. The far-field intensity pattern of the combined beam has high energy concentration and good beam quality. The power encircled in the main lobe of the far-field pattern is 41.3%, and the contrast of the pattern reaches 81.8%. Experimental results show the great potential of the Hartmann phasing method for use in the CBC of a large number of laser beams. 相似文献
33.
针对目前关于退火温度对原子层沉积法(ALD)制备ZnMgO薄膜晶体结构和光学性质影响鲜有报道的现象,进行了相应的实验研究分析。采用ALD在石英衬底上制备ZnMgO合金薄膜,对制得的样品在空气中进行不同温度的退火处理。利用X射线多晶衍射仪(XRD)、光致发光谱(PL)和紫外可见(UV-Vis)吸收光谱测试,系统的分析了不同退火温度对ALD法制备ZnMgO薄膜晶体结构和光学性能的影响。XRD测试结果表明:退火温度为600 ℃时,薄膜的晶体质量得到改善,且(100)衍射峰的强度明显增强。结合PL和UV-Vis吸收光谱的测试分析得出:退火温度为600 ℃时,能明显促进薄膜中Mg组分的增加使薄膜的禁带宽度进一步增大。从而说明适当温度的退火处理可有效的改善ZnMgO薄膜的晶体质量及光学特性。 相似文献
34.
加速溶剂萃取/气相色谱-负化学电离质谱法对土壤中毒杀芬的测定研究 总被引:3,自引:0,他引:3
建立了加速溶剂萃取/气相色谱-负化学电离质谱法测定土壤中毒杀芬的方法.在加速溶剂萃取实验条件优化的基础上,确定了最佳实验条件:系统压力12.4 MPa,萃取溶剂为正己烷-丙酮(体积比1 : 1),萃取温度100 ℃,静态萃取时间10 min,循环2次.萃取液经活性炭与弗罗里硅土复合小柱净化后,氮吹至1.0 mL,于GC-MS仪上测定.结果表明,毒杀芬的线性范围为0.3 ~3 000 ng/g(毒杀芬总量),相关系数均不小于0.999 0,方法检出限为0.10 ~1.00 ng/g,平均回收率为86% ~104%,相对标准偏差(n=7)为6.8% ~13.5%. 相似文献
35.
36.
基于VO_2的热致相变特性,仿真设计出了一种W/VO_2方形纳米柱阵列可调中红外宽频吸收器,通过时域有限差分法分析了结构参数对吸收性能和结构内电磁场强度分布的影响,以及吸收器在不同偏振态和入射角度下的吸收特性。结果表明:在最佳的结构参数下,当VO_2未发生相变时,入射到吸收器的红外光转变为热而消耗掉,在3~5μm谱段的平均吸收率高达96.2%;当VO_2发生相变而转变为金属相时,吸收器表现出强反射,抑制吸收,高低温下的平均吸收率差可达74.1%。该吸收器的吸收率受入射光的影响较小,具有广角吸收特性,有望在红外智能光电领域得到应用。 相似文献
37.
为突破传统衍射极限实现远场超分辨率成像,提出了一种微波频段宽带立体超透镜用于目标远场超分辨率成像.该透镜可将携带着目标超分辨率信息的凋落波分量转换为传播波分量辐射到远场,进而可在远场接收这些信息并用于超分辨率成像.分别从频域和时域两方面对该透镜的超分辨率特性进行验证.在频域,利用多重信号分类算法对借助于该结构的扩展目标实现了λ/12的远场超分辨率成像,大幅度提升了成像效果.在时域,结合时间反演技术,验证了带宽提升对空间超分辨率聚焦特性带来的明显优势. 相似文献
38.
利用时域有限差分法研究了Au纳米天线对GaSb纳米线的消光增强.通过分析不同形状Au纳米阵列的电场特性和光学特性,发现三角形为最优结构,并具有高强度共振吸收峰和高的电场增强倍数.分别对三角形尺寸和纳米线的间距进行调节,结果表明:随着尺寸由70nm增加到210nm,消光峰位从783nm单调增加到1 638nm,峰位强度和电场增强倍数逐渐增加,尺寸为210nm时的增强倍数为70nm时的6倍;随着间距由80nm增加到130nm,消光峰位从1 655nm减小到1 460nm,峰位强度和电场增强倍数略微减小.因此可通过先调节间距再调节尺寸的方法来设计Au纳米天线结构. 相似文献
39.
The influence of the Dresselhaus spin--orbit coupling on the tunnelling magnetoresistance in ferromagnet/ insulator /semiconductor/ insulator /ferromagnet tunnel junctions
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This paper investigates the effect of Dresselhaus spin--orbit
coupling on the spin-transport properties of
ferromagnet/insulator/semiconductor/insulator/ferromagnet
double-barrier structures. The influence of the thickness of the
insulator between the ferromagnet and the semiconductor on the
polarization is also considered. The obtained results indicate that
(i) the polarization can be enhanced by reducing the insulator
layers at zero temperature, and (ii) the tunnelling magnetoresistance
inversion can be illustrated by the influence of the Dresselhaus
spin--orbit coupling effect in the double-barrier structure. Due to
the Dresselhaus spin--orbit coupling effect, the tunnelling
magnetoresistance inversion occurs when the energy of a localized
state in the barrier matches the Fermi energy EF of the
ferromagnetic electrodes. 相似文献
40.
In this paper, we propose a simple model that can generate
small-world network with community structure. The network is
introduced as a tunable community organization with parameter r,
which is directly measured by the ratio of inter- to intra-community
connectivity, and a smaller r corresponds to a stronger community
structure. The structure properties, including the degree
distribution, clustering, the communication efficiency and
modularity are also analysed for the network. In addition, by using
the Kuramoto model, we investigated the phase synchronization on
this network, and found that increasing the fuzziness of community
structure will markedly enhance the network synchronizability;
however, in an abnormal region (r ≤ 0.001), the network has even
worse synchronizability than the case of isolated communities (r =
0). Furthermore, this network exhibits a remarkable
synchronization behaviour in topological scales: the oscillators of
high densely interconnected communities synchronize more easily, and
more rapidly than the whole network. 相似文献