热端温度对高频微型同轴脉冲管制冷机性能的影响及其在空间技术中的应用研究

本文用数值方法对热端温度对微型高频同轴脉冲管制冷机性能的影响进行了分析,并将其与实验结果进行了比较,随着热端温度的升高,制冷机的最低制冷温度单调升高,制冷量单调减少,试验结果与数值计算结果定性相符。在此基础上,探讨了高频微型同轴脉冲管制冷机和辐射制冷器相结合在空间飞行器中的应用,提出了两种应用模式,用数值方法对之进行了分析。     

多光束激光干涉光刻图样

利用电磁理论,研究了多光束激光干涉图样的产生原理,结合计算机数值模拟和相关实验结果,分析了干涉图样的影响因素。研究结果表明：多光束激光干涉图样可以看成是多组余弦分布的平行线条纹的叠加;相干光束的偏振方向、入射方向、光束间相差是干涉图样的重要影响因素,改变这些因素,余弦分布的平行线条纹的振幅、置、周期和方向发生变化,图样也随之变化。     

Spin gapless semiconductor like Ti2MnAl film as a new candidate for spintronics application

A novel Heusler ferrimagnet Ti₂MnAl film has been grown on Si(001) substrate using magnetron sputtering. Characteristics of its magnetic and transport properties reveal the spin‐gapless‐semiconductor (SGS) nature of the stoichiometric Ti₂MnAl, in agreement with theoretical prediction. The as‐grown SGS‐like Ti₂MnAl film demonstrated high Curie temperature, nearly compensated ferrimagnetic properties with small coercivity and low magnetization. It also showed semiconductor‐like behavior at room temperature allowing good compatibility with commercial Si‐based semiconductor. In this regards, Ti₂MnAl film is a potential candidate material for spintronics application, especially for the minimization of energy consumption of device. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

In situ X‐ray data collection and structure phasing of protein crystals at Structural Biology Center 19‐ID

A prototype of a 96‐well plate scanner for in situ data collection has been developed at the Structural Biology Center (SBC) beamline 19‐ID, located at the Advanced Photon Source, USA. The applicability of this instrument for protein crystal diffraction screening and data collection at ambient temperature has been demonstrated. Several different protein crystals, including selenium‐labeled, were used for data collection and successful SAD phasing. Without the common procedure of crystal handling and subsequent cryo‐cooling for data collection at T = 100 K, crystals in a crystallization buffer show remarkably low mosaicity (<0.1°) until deterioration by radiation damage occurs. Data presented here show that cryo‐cooling can cause some unexpected structural changes. Based on the results of this study, the integration of the plate scanner into the 19‐ID end‐station with automated controls is being prepared. With improvement of hardware and software, in situ data collection will become available for the SBC user program including remote access.     

具有P型覆盖层新型超级结横向双扩散功率器件

为了设计功率集成电路所需要的低功耗横向双扩散金属氧化物半导体器件(lateral double-diffused MOSFET), 在已有的N型缓冲层超级结LDMOS(N-buffered-SJ-LDMOS)结构基础上, 提出了一种具有P型覆盖层新型超级结LDMOS结构(P-covered-SJ-LDMOS). 这种结构不但能够消除传统的N沟道SJ-LDMOS由于P型衬底产生的衬底辅助耗尽问题, 使得超级结层的N区和P区的电荷完全补偿, 而且还能利用覆盖层的电荷补偿作用, 提高N型缓冲层浓度, 从而降低了器件的比导通电阻. 利用三维仿真软件ISE分析表明, 在漂移区长度均为10 μm的情况下, P-covered-SJ-LDMOS的比导通电阻较一般SJ-LDMOS结构降低了59%左右, 较文献提出的N型缓冲层 SJ-LDMOS(N-buffered-SJ-LDMOS)结构降低了43%左右.     

Perforated nanocap array: Facile fabrication process and efficient surface enhanced Raman scattering with fluorescence suppression

Recently, individual reduced-symmetry metal nanostructures and their plasmonic properties have been studied extensively. However, little attention has been paid to the approach to fabricating ordered reduced-symmetry metal nanostructure arrays. In this paper, a novel perforated silver nanocap array with high surface-enhanced Raman scattering (SERS) activity and fluorescence suppression is reported. The array is fabricated by electron beam evaporating Ag onto the perforated barrier layer side of a hard anodization (HA) anodic aluminum oxide (AAO) template. The morphology and optical property of the perforated silver nanocap array are characterized by an atomic force microscope (AFM), a scanning electron microscope (SEM), and absorption spectra. The results of SERS measurements reveal that the perforated silver nanocap array offers high SERS activity and fluorescence suppression compared with an imperforated silver nanocap array.     

X波段左手材料高功率微波天线罩实验研究

为改善高功率微波天线的性能,设计了一种新型X波段左手材料高功率微波天线罩,并对其进行了实验冷测研究。结果表明,加载一到四层左手材料天线罩均可在一定频率范围内汇聚波束和提高增益,其中加载一层左手材料天线罩时,天线增益提高最大,在频率为9.32 GHz时增益提高最大幅度约为9.64 dB。将实验结果与理论仿真进行对比发现,两者并没有吻合一致。分析了天线罩的功率容量,可以实现高功率微波的应用。     

Network connectivity entropy and its application on network connectivity reliability

The network structure entropy has served as one of the index measuring network heterogeneity, but it gives no considerations to the impact of isolated nodes on the network structure. In addition, the all-terminal reliability is zero and is unable to compare it between disconnected networks. Therefore, the concept of network connectivity entropy is suggested to remove the current bottleneck and helps facilitate new index in terms of network connectivity reliability. This study fully proves the rules as follows: when the edges of network are diminishing, the newly-established network connectivity reliability will remain unchanged or become weaker; conversely, when the edges of network are increasing, the network connectivity reliability will remain unchanged or become stronger. Thus, the proposed index of network connectivity reliability is proved reasonable. Furthermore, the impaired metro network of Nanjing city is exemplified to demonstrate the validity and practicability of network connectivity reliability. The result shows that this new approach is in good position to compute network connectivity reliability quickly and effectively, and also to compare it between different networks.