高辐射效率超宽谱脉冲辐射天线的设计与实验

设计了一种采用共面TEM馈电结构的抛物反射面超宽谱脉冲辐射天线,分析了该种馈电结构的阻抗特性与辐射特性。实验表明当馈入电压为3kV、前沿180ps的超宽谱脉冲时,该天线主轴辐射场测试距离与峰值场强之积平均值达到18.3kV,相较于常用的TEM喇叭馈电的超宽带反射面天线,其辐射效率有了显著的提高。     

Room-Temperature Magnetism Realized by Doping Fe into Ferroelectric LiTaO3

We synthesize LiTal-x FexO3-σ （LTFO） remain single phase up to x = 0.09 ceramics by the conventional solid-state reaction method. The samples The magnetic measurements show that the doping of Fe successfully realizes ferromagnetism of LTFO at room temperature. The dielectric measurements indicate that LTFO is ferroelectric, similarly to LiTaO3 （LTO）, but its ferroelectric Curie temperature seems to decrease with the increasing Fe content. By means of doping Fe ions into LTO, the coexistence of spontaneous electric polarization and spontaneous magnetic moment is realized at room temperature.     

A diode laser spectrometer at 634nm and absolute frequency measurements using optical frequency comb

This paper reports that two identical external-cavity-diode-laser (ECDL) based spectrometers are constructed at 634 nm referencing on the hyperfine B-X transition R(80)8-4 of ¹²⁷I₂. The lasers are stabilized on the Doppler-free absorption signals using the third-harmonic detection technique. The instability of the stabilized laser is measured to be 2.8×10^-12 (after 1000 s) by counting the beat note between the two lasers. The absolute optical frequency of the transition is, for the first time, determined to be 472851936189.5 kHz by using an optical frequency comb referenced on the microwave caesium atomic clock. The uncertainty of the measurement is less than 4.9 kHz.     

EAST装置内置低温冷凝泵低温分配阀箱的研制

在全超导磁约束核聚变试验装置EAST中,为了防止杂质从偏虑器靶板附近进入等离子体核心,为EAST长脉冲放电试验提供持续的排灰能力以及装置长冲放电等,低温冷凝泵是必不可少的部件之一,在装置真空室上下安装了内置低温凝泵以提高装置运行参数,为满足低温泵的低温条件,增加一低温分配阀箱给内置低温冷凝泵提供低温条件。文中介绍应用于EAST装置系统中的内置低温冷凝泵分配阀箱研制的技术要求、冷却流程、结构特征。     

环中环结构谐振腔中的耦合谐振透明特性研究

在考虑耦合器插入损耗的情况下,理论分析了环中环结构谐振腔的耦合谐振透明效应.利用迭代法推导了整个结构的透过系数和有效相移,从而得到考虑了插入损耗的该结构的色散.研究表明,整个结构的有效相移,群速度和带宽,可通过耦合器的插入损耗、环中环结构中环与环周长之间的倍数以及环的个数来控制,这在旋转传感、光学时延线、光缓存、滤波等方面的应用有重要意义. 关键词： 环中环结构 耦合谐振透明 色散 慢光     

Influence of laser mode on splitting beam illumination effect of Dammann grating

The influences of various laser modes on the splitting beam effect of Dammann grating are studied in theory and by numerical simulation. The results show that fundamental mode laser resembles plane wave while high order mode laser differs from plane wave in the splitting beam effect by Dammann grating. Therefore, the fundamental mode laser is more suitable to be the light source to improve the energy efficiency in far-distance image detecting systems, such as laser image ladar, which use Dammann grating in the ilhlmination svstem.     

Thermal Transport in One-Dimensional FPU-FK Lattices

Thermal transport in the FPU model with Kutta algorithm. The heat flux, local temperature profile, that temperature gradient scales behave as N-1 linearly. FK on-site potential is studied by using fourth-order Runge- and heat conductivity axe simulated and analyzed. It is found The divergence of heat conductivity ~ with system size N is in term of κ ∝ N^α with α = 0.44. It is shown that thermal transport is mainly dependent on the FPU nonlinear and the FK interactions.     

单方环结构左手材料微带天线

设计了一种简单的双面单方环结构左手材料,在4.8–5.25 GHz频率范围内该材料的等效介电常数和等效磁导率同时为负.将此单方环左手材料作为覆盖层,置于中心工作频率为5.0 GHz的微带天线之上. 仿真和实验研究表明:相对普通微带天线而言,覆层微带天线的性能得到了明显改善, E面和H面的半功率波束宽度分别收缩了25°和20°,定向性得到了提高, 5 GHz处的增益提高了3 dB, -10 dB带宽增加了600 MHz. 关键词： 单方环结构 左手材料 微带天线     

大鼠粪样中几种糖类物质的结构确定

粪样代谢组能够反映宿主和肠道菌群相互作用的共代谢信息,然而粪样中糖类物质的归属信息迄今仍不完善. 该研究使用1D NMR技术检测到大鼠粪样中木糖、阿拉伯糖、半乳糖等单糖以及由阿拉伯糖和木糖组成的寡聚糖. 在使用固相萃取（SPE）方法进行分离富集的基础上,结合使用2D NMR实验技术（¹H-¹H COSY,¹H-¹H TOCSY,¹H-¹³C HSQC,¹H-¹³C HMBC以及DOSY）确定了这些糖类物质的结构,并对其1H NMR和¹³C NMR谱峰进行了归属.