放电引发非链式脉冲HF/ DF 激光器的研究进展

文中介绍了放电引发的非链式脉冲HF／DF激光器三十年来的研究进展，分析讨论了此类激光器的发展趋势。     

激光器窗口的旋转效应

通过数值计算比较研究了静止、同心旋转、偏心旋转三种模式下高能激光器窗口工作过程中温度场和应力场的特征及其演变规律。研究表明，旋转式激光器窗口不但可使温度场和应力场轴对称化，且可降低最高温升、最大拉应力和最大剪应力；一定偏心距的偏心旋转可以起到消去拉应力、减小剪切应力的作用，从而使激光器窗口的抗激光损伤的能力有较大幅度的提高。     

Bounded sets structure of CpX and quasi‐(DF)‐spaces

For wide classes of locally convex spaces, in particular, for the space $C_p(X)$ of continuous real‐valued functions on a Tychonoff space X equipped with the pointwise topology, we characterize the existence of a fundamental bounded resolution (i.e., an increasing family of bounded sets indexed by the irrationals which swallows the bounded sets). These facts together with some results from Grothendieck's theory of $(DF)$‐spaces have led us to introduce quasi‐ $(DF)$‐spaces, a class of locally convex spaces containing $(DF)$‐spaces that preserves subspaces, countable direct sums and countable products. Regular $(LM)$‐spaces as well as their strong duals are quasi‐ $(DF)$‐spaces. Hence the space of distributions $D^{\prime }(\mathrm{\Omega })$ provides a concrete example of a quasi‐ $(DF)$‐space not being a $(DF)$‐space. We show that $C_p(X)$ has a fundamental bounded resolution if and only if $C_p(X)$ is a quasi‐ $(DF)$‐space if and only if the strong dual of $C_p(X)$ is a quasi‐ $(DF)$‐space if and only if X is countable. If X is metrizable, then $C_k(X)$ is a quasi‐ $(DF)$‐space if and only if X is a σ‐compact Polish space.     

van der Waals corrected density functional calculations of the adsorption of benzene on the Cu (111) surface

We investigate the performance of several van der Waals (vdW) functionals at calculating the interactions between benzene and the copper (111) surface, using the local orbital approach in the SIESTA code. We demonstrate the importance of using surface optimized basis sets to calculate properties of pure surfaces, including surface energies and the work function. We quantify the errors created using (3 × 3) supercells to study adsorbate interactions using much larger supercells, and show non‐negligible errors in the binding energies and separation distances. We examine the eight high‐symmetry orientations of benzene on the Cu (111) surface, reporting the binding energies, separation distance, and change in work function. The optimized vdW‐DF(optB88‐vdW) functional provides superior results to the vdW‐DF(revPBE) and vdW‐DF2(rPW86) functionals, and closely matches the experimental and experimentally deduced values. This work demonstrates that local orbital methods using appropriate basis sets combined with a vdW functional can model adsorption between metal surfaces and organic molecules.     

Performance analysis of cooperative spatial multiplexing networks with AF/DF relaying and linear receiver over Rayleigh fading channels

Cooperative spatial multiplexing (CSM) system has played an important role in wireless networks by offering a substantial improvement in multiplexing gain compared with its cooperative diversity counterpart. However, there is a limited number of research works that consider the performance of CSM systems. As such, in this paper, we have derived exact performance of CSM with amplify‐and‐forward and decode‐and‐forward relays in terms of outage capacity and ergodic capacity. We have shown that CSM systems yield a unity diversity order regardless of the number of antennas at the destination and the number of relays in the networks, which is the direct result of diversity and multiplexing gain trade‐off. Our analytical expressions are corroborated by Monte‐Carlo simulations. Copyright © 2013 John Wiley & Sons, Ltd.     

非链式HF/DF激光器的研究进展

HF/DF激光器是中红外波段能提供最高能量输出的激光光源,也是中红外波段应用非常广泛的相干光源。本文介绍了近几年国内外关于非链式HF/DF激光器的研究进展及其成果应用,分析了非链式HF/DF激光器在应用方面的优缺点,总结了实现非链式HF/DF激光输出的关键技术和存在的问题,指出了该技术的未来发展方向。     

＂Amano＂ lipase DF-catalyzed efficient synthesis of 2,2＇-arylmethylene dicyclohexane-1,3-dione derivatives in anhydrous media

A simple and efficient method was developed for the synthesis of 2.2＇-arylmethylene dicyclohexane-1,3- dione derivatives via the Knoevenagel-Michael cascade reactions of aromatic aldehydes and 1,3-cyclic diketones catalyzed by ＂Amano＂ lipase DF, which expands the application field of enzyme catalytic promiscuity. This protocol provides several advantages over the traditional chemical synthesis, such as simple work-up procedure, high yields Cup to 94%） and environmental friendliness.     

High Resolution Crossed Beams Scattering Study of the F＋HD→DF＋H Reaction

Crossed beams scattering study was carried out on the F＋HD→DF＋H reaction using high- resolution H-atom Rydberg tagging time-of-flight technique. Vibrational state-resolved differential cross sections were measured, with partial rotational state resolution, at eight collision energies in the range of 2.51-5.60 kJ/mol. Experimental results indicated that the product angular distributions are predominantly backward scattered. As the collision energy increases, the backward scattered peak becomes broader gradually. Dependence of product vibration branching ratios on the collision energy was also determined. The experimental results show that the DF products are highly inverted in the vibrational state distribution and the DF （v＇=3） product is the most populated state. Furthermore, the DF （v＇=l） product has also been observed at collision energy above 3.97 kJ/mol.     

一种基于干涉仪体制的机载测向技术研究

详细分析了机载测向系统特点以及干涉仪测向原理,讨论了适合机载环境的测向天线阵阵元个数、阵列孔径与无模糊测向以及测向精度的关系。针对机载测向天线易受金属机体二次反射影响和安装空间受限等特点,给出了一种适合机载安装条件的9阵元椭圆型测向天线阵的设计并进行了性能分析和仿真验证。仿真结果表明,选用该测向天线阵,系统具有较强的抑制相位畸变能力和较好的测向精度。     

网络-信道联合编码的DmF协作通信技术

提出了一种采用网络-信道编码的解调前传(DmF)协作通信方案.与译码前传(DF)相比,DmF协作方式在中继处只对信号进行解调而非译码,因此,大大降低了中继节点的复杂度.在由两个用户、一个中继节点和一个基站组成的通信模型中,采用LDPC信道编码与网络编码结合的方式,构造了一种DmF协作传输方式.在基站处,通过构造的H矩阵对来自两用户及中继的信号进行联合译码.仿真结果表明:所给方案的性能优于非协作方式及无网络编码的协作通信方式,随着信噪比的增加这种优势会更加明显;另外,DmF的性能与DF的非常接近,但其设备复杂度却大大降低,因此DmF比DF方式更具实用性.同时,该方案在降低设备复杂度、减少延迟、有效对抗无线信道慢衰落、提高通信性能及频谱利用率等方面都是非常有效的.