连续钛宝石激光器长波段调谐的实验研究

本文主要报导用钛宝石进行长波段激光调谐的实验结果。钛宝石晶体（φ４×１１．５ｍｍ）置于四镜Ｚ形驻波腔内，由氩离子激光器全线轴向泵浦，激光波长由石英双折射滤光片调谐。在８Ｗ功率泵浦时，钛宝石激光器调谐范围是９０１．６ｎｍ到１０００．０ｎｍ；当泵浦功率为８．９Ｗ时，１００５．０ｎｍ处激光输出超过１５ｍＷ．９８０ｎｍ处钛宝石激光器的阈值为６．６Ｗ，斜率效率为３．７％；当泵浦功率为１０．５Ｗ时，激光连续输出达１５５ｍＷ。同时还对实验结果和双折射调谐器的设计进行了分析。     

Thermosolutal convection between poorly conducting plates

Thermosolutal convection is considered in a fluid layer between poorly conducting horizontal boudaries. The horizontal scale of the motions is much greater than the depth of the fluid layer, provided the motion is not too vigorous, and this disparity between horizontal and vertical scales provides the basis foe an asymptotic expansion of the solution. Under the assumption of near-constant solute-flux at the horizontal boundaries, a pair of evolution equations is derived for the depth-averaged temperature and solute concentration fields.These long-wave equations are investigated for two-dimensional convection by numerical integrations, and the results are compared with linear and weakly non-linear theory. The asymptotic expansion is shown to break down for large values of R, when the form assumed for the convection becomes inappropriate.The onset of three-dimensional convection is analysed. Steady square convection cells are stable. Oscillatory convection in the form of two-dimensional travelling-wave rolls is stable to three-dimensional disturbances near onset.     

长波红外无线激光通信技术研究现状

考虑到8～14μm长波红外激光在大气中传输特性优于常用的近红外激光,长波红外无线激光通信技术成为研究热点.比较了长波红外激光与近红外激光在大气中的传输性能,介绍国内外长波红外无线激光通信技术研究情况,并对系统主要关键组件进行了说明.     

紧凑型长波致冷红外变焦距透镜系统

针对国际新型长波致冷324×256红外焦平面探测器,设计一款红外变焦距透镜系统。光学系统整体采用四片光学锗透镜大大节省材料的使用,在变焦过程中系统的相对孔径恒定不变,F数2,焦距在30～90 mm范围内连续可变,变倍比为3:1。系统采用二次成像技术,既解决了系统前端口径大的问题也实现了100%冷光阑效率的问题。非球面及衍射面的使用进一步简化系统、减轻重量。利用通用光学设计软件CODE V优化系统,设计结果表明:在空间频率20 lp/mm处,系统各个典型视场的MTF接近衍射极限,成像质量较好。     

Empirical validation of different internal superficial heat transfer models on a full-scale passive house

Being highly insulated, low-energy buildings are very sensitive to variable solar and internal gains. In this context, some modelling assumptions frequently used in simplified building energy simulation tools might be called into question. While higher insulation levels reduce the influence of heat transmission through opaque walls, absorption of solar and internal gains at inner wall surfaces, and indoor superficial heat transfers, become concerning. The convective and long-wave radiative heat transfer models are investigated in COMFIE, a dynamic energy simulation platform. More detailed internal heat transfer models are developed by decoupling convective and long-wave radiative heat transfers and using time-dependent coefficients. Furthermore, an empirical validation process on both simplified and detailed models is carried out using measurements from a full-scale experimental concrete passive house, addressing the model uncertainty vs. complexity issue.     

The solitary wave solution of the two-dimensional regularized long-wave equation in fluids and plasmas

This paper investigates the solitary wave solutions of the two-dimensional regularized long-wave equation which is arising in the investigation of the Rossby waves in rotating flows and the drift waves in plasmas. The main idea behind the numerical solution is to use a combination of boundary knot method and the analog equation method. The boundary knot method is a meshless boundary-type radial basis function collocation technique. In contrast with the method of fundamental solution, the boundary knot method uses the non-singular general solution instead of the singular fundamental solution to obtain the homogeneous solution. Similar to method of fundamental solution, the radial basis function is employed to approximate the particular solution via the dual reciprocity principle. In the current paper, we applied the idea of analog equation method. According to the analog equation method, the nonlinear governing operator is replaced by an equivalent nonhomogeneous linear one with known fundamental solution and under the same boundary conditions. Furthermore, in order to show the efficiency and accuracy of the proposed method, the present work is compared with finite difference scheme. The new method is analyzed for the local truncation error and the conservation properties. The results of several numerical experiments are given for both the single and double-soliton waves.     

长波甚低频通信固定台站空袭防御问题探讨

海军舰船历来是军事强国走出国门、走向海洋的重要移动平台,而长波甚低频通信是海军舰船远程应急通信保障的主要手段之一.从长波甚低频通信固定台站可能受到空中兵力兵器攻击的可能性入手,提出了建立观察、警戒与预警防御网络,构筑工事、掩体等地下防御体系,加强信息传输安全保密,研演空袭防御各种战术等对策措施.     

长短波方程的两个守恒型紧致有限差分格式

本文对一类耦合非线性长短波方程组进行了数值研究，提出了两个四阶紧致有限差分格式，并证明新格式在离散意义下保持原问题的两个守恒性质，即总质量守恒和总能量守恒．数值实验表明本文格式在时间和空间方向分别具有二阶和四阶精度，具有良好的稳定性且在离散意义下很好地保持总质量和总能量守恒．     

3D打印用长波紫外光固化树脂的制备

通过优化引发剂的种类和用量,得到一系列阳离子和自由基混杂体系光固化树脂,并用旋转流变仪和SLA型3D打印机进行长波紫外光固化和3D打印成型。结果表明:与芳基鎓盐类阳离子光引发剂PAG202相比,芳茂铁盐类阳离子光引发剂261具有长波紫外光固化的适应性,而光敏增感剂PAS-50对光引发剂261敏化显著,在长波紫外光下光引发剂261/PAS-50体系能快速引发树脂固化。最佳配方时,固化树脂的弯曲模量高于国内外同类树脂的,且具有较低的固化收缩率。     

长波天线大跨越导线的防微风振动设计

长波天线一般架设于陆地平原或山谷中,多采用大跨越导线等作为辐射体,在水下通信中扮演着重要角色。由微风荷载引起的导线长时间、高频小幅振动,会使导线发生疲劳破坏,从而引发断股、断线、金具连接破裂、失效等事故,具有巨大的破坏性。目前,对于长波天线的微风振动研究还未见到相关报道。文中从微风振动的起因入手,对影响长波天线导线振动的因素进行了分析,并结合实际工程对某长波天线大跨越导线进行了防振设计,所采用的多方式联合防振方法,经实测效果良好,相关经验可为后续的长波台的防振设计提供一定参考。