Numerical simulations of the impact of wavefront phase distortions of pump on the beam quality of OPA

<正>A numerical model of optical parametric amplification(OPA) is introduced to investigate the impact of wavefront phase distortion of pump on the beam quality of signal.Numerical results show that the unidentical walk-off directions of the pump and the idler waves are the main factors leading to the transfer of wavefront phase distortions of the pump to the signal,and by reducing the angle between the two directions,the beam quality factor(M~2) can be greatly decreased and hence the good beam quality of the signal can be maintained.     

Molecular-Dynamics Simulations of Droplets on a Solid Surface

By using a semi-empirical Lennard-Jones embedded-atom-method potential, we study the influence of many-body forces and atomic size mismatch on the wetting behavior of nano droplets on a solid surface. With molecular dynamics simulations, we find that the contact angle decreases with increasing many-body forces. The increase of atomic size mismatch between solid and liquid results in the decrease of contact angles. Our calculation also shows that the interface structure is strongly affected by the interaction between liquid and solid as well as the atomic size mismatch. For weak solid-liquid interaction, the interface layer of the droplet nearest to the solid exhibits a typical simple liquid structure regardless of the size mismatch. For strong solid-liquid interaction, evident ordering in the interface layer is observed for well matched cases.     

Study of scalar meson a0（980） from B → a0（980）π decays

In this paper, we calculate the branching ratios and the direct CP-violating asymmetries for decays B^0 → a0^0（980）π^0, a0^＋ （980）π^-, a0^-（980）π^＋ and B^- → a0^0 （980）π^-, a0^- （980）π^0 by employing the perturbative QCD （pQCD） factorization approach at the leading order. We found that （a） the pQCD predictions for the branching ratios are around （0.4-2.8） × 10^-6, consistent with currently available experimental upper limits; （b） the CP asymmetries of B^0→ a0^0（980）π^0 and B^- → a0^- （980）π^0 decays can be large, about （70-80）% for α= 100°.     

基于双向搜索方法的最小值控制递归平均语音增强算法

语音增强效果的提高,有赖于对噪声的准确估计和对噪声变化的及时跟踪与更新。为了提高对非平稳噪声的估计和更新能力,本文基于\     

A new beam asymmetry measurement from pion photoproduction on the neutron using CLAS

We present a preliminary analysis of the photon beam asymmetry observable （Z） from the pho- toproduction reaction channel γn → pπ in the invariant mass range 1.6--2.3 GeV. The measurement was obtained using the near-4π CEBAF Large Acceptance Spectrometer （CLAS） at Jefferson Laboratory, USA, employing a linearly polarised photon beam with an energy range 1.1 2.3 GeV, incident on a liquid deuterium target. The measurement will provide new data to address the poorly established neutron excitation spectrum and will greatly expand the sparse world data-set both in energy and angle.     

Nucleon aPF2 Superfluid Pairing Gap in Asymmetry Nuclear Matter

The 3 P F2 superfluidity of neutron and proton is investigated in isospin-asymmetric nuclear matter within the Brueckner-Hartree-Fock approach and the BCS theory by adopting the Argonne V14 and the Argonne V18 nucleonnucleon interactions. We find that pairing gaps in the 3PF2 channel predicted by adopting the AV14 interaction are much larger than those by the AV18 interaction. As the isospin-asymmetry increases, the neutron 3 pF2 superfluidity is found to increase rapidly, whereas the proton one turns out to decrease and may even vanish at high enough asymmetries. As a consequence, the neutron 3pF2 superfluidity is much stronger than the proton one at high asymmetries and it predominates over the proton one in dense neutron-rich matter.     

土壤源热泵在合肥某工程中的应用

介绍了土壤源热泵的工作原理,探讨了土壤源热泵空调应用于中央空调系统的设计方法,以及其主要部件地热换热器的埋管方式、结构、管材、运行等特点。选取几种常用的冷热源系统与土壤源热泵系统进行比较分析,参考合肥地区的能源价格,计算各方案的运行成本,用动态费用年值法对各方案的经济性进行了评价。     

激光监听实验的开设与研究

本文介绍了综合、设计性实验——激光监听实验的开设过程,以及对影响实验效果若干因素的研究。     

钛钒铁间吸收增强效应研究及其校正

利用X射线荧光分析方法,采用电制冷Sic(PIN)探测器,对配制的Ti-V,Ti-Fe,V-Fe三种伪二元体系样品进行测量,得到了元素计数率归一系数(RK)与含最(WK)之间的关系曲线,对各组元素间的吸收-增强效应程度进行了定性分析.结果表明,Ti-V二元系中所表现的吸收增强效应较明显,Ti-Fe,V-Fe两种二元系中吸收增强现象不明显.同时,采用指数拟合的数学校正方法,对RK-WK关系曲线进行了拟合,从而获得元素X射线荧光计数率与含垦的函数方程.利用三组Ti-V二元系样品对此方法进行检验,与实际结果相比,对Ti,V元素的相对分析误差均在0.2%以内.     

双近贴式X射线像增强器成像不均匀性的分析与校正

分析了双近贴式X射线像增强器响应不一致性的产生机理,对每个像元建立了光电响应的数学模型.基于该模型,提出了一种改进的多点校正算法.该算法将对数曲线模型转化为线性响应模型,通过基于最小二乘法的两点拟合算法对图像数据进行校正.对比分析了校正前后图像的背景标准差及灰度分布曲线,实验结果验证了该方法的有效性.