以RBCC为动力的巡航飞行器轨迹与质量分析

巡航飞行器正向着远程、高超声速巡航、高弹道的方向发展,RBCC(火箭基组合循环)推进系统是此类巡航飞行器的潜在动力。文中建立了以RBCC为动力的巡航飞行器的飞行轨迹和质量分析数学模型,并针对特定技术参数要求的巡航飞行器进行了求解,考虑了飞行动压和过载的限制。结果表明,当惰性质量系数有效地控制在一定范围之内时,RBCC发动机作为巡航飞行器推进系统是可行的,且飞行器具有良好的总体性能,同时有效载荷会随着惰性质量系数的减小而增加。     

梯度材料三维稳态温度场的改进分层计算方法

针对每层热传导系数为常数的分层计算模型，采用功能梯度材料（FGM）每层热传导系数为指数变化规律，对原计算模型进行改造，消除了每层热传导系数跳跃性，得到稳态温度场的温度分布计算公式。计算结果表明，精度相同时，热传导系数为指数变化规律分层计算模型收敛速度是热传导系数为常数的分层计算模型的3倍多，精度越高，收敛速度越快。     

低频非均匀电磁波在导电界面的反射相角

基于非均匀电磁波在导电媒质中传播时其相移常数和振幅衰减方向的不一致性，根据电磁场边值关系建立了导电介质中电磁波的相移常数向量和振幅衰减向量方向的定量关系，实现了将相移常数向量和振幅衰减向量的两个方向统一用一个角度表示. 对于低频非均匀平面电磁波，给出了满足低频条件的低频非均匀电磁波在导电界面反射时的反射系数，利用低频非均匀电磁波在导电界面的反射系数导出了电场偏振化方向在入射面内和垂直于入射面的电磁波在导电界面的反射相角，确立了低频非均匀电磁波反射附加相角随入射角的变化关系. 由此发现：入射角在0°到90°范围内非均匀电磁波的反射波都存在附加相角，这与反射光的反射附加相角存在较大的差异.     

区域主导产业分析方法研究综述

区域主导产业是构建区域核心竞争力的一个重要方面。区域主导产业的选择可以从定性和定量两个方面去分析。定性基准包括主导部门分析法基准、产业关联基准、收人弹性基准和生产率上升基准、比较优势基准等。定量的方法包括区外相对比较优势度分析方法、产业关联度分析方法、市场潜在需求率分析方法等。     

桂林桃花江水环境容量研究

对桃花江水环境容量进行了初步研究,系统调查了桃花江沿岸主要排污口,分析了其污染特征.根据其水文水质特点,选择一维推流模型,在枯水期现场取样,采用室内振荡实验,确定了水质模型中的综合衰减系数为:KCODMn=0.30 d-1,KNH3-N=0.35 d-1.据此计算出各控制单元的水环境容量及不同规划水平年污染物排放量和削减量:伍仙桥至飞鸾桥河段的CODMn、NH3-N理论削减量,2010年分别为879和470.8 kg/d,2015年分别为901和477.8 kg/d,将远远超过相应河段的水环境容量.北冲污水处理厂排放的“尾水”将是水污染治理的重点,也是改善桃花江水环境质量的关键.     

三峡库区滑坡治理中抗滑桩锚固深度的研究

分析了三峡库区滑坡治理中抗滑桩锚固深度一般取桩长的1／2～1／3存在的问题。用弹性地基系数法，计算了弹性桩作用于桩侧岩土体的应力。滑动面为倾斜面时，对桩前岩体中存在的不利结构面进行抗滑稳定性验算，得出抗滑桩的最小锚固深度，提出了根据桩周岩土体的性质来确定桩侧岩土体的横向容许承载力。工程实例表明：桩的锚固深度的确定可以依据桩的不同结构形式，稳定地层的强度，滑坡推力，桩的刚度，桩的截面和间距及是否考虑桩前滑体的抗力等因素综合确定。     

Importance of Third Virial Coefficients for Representing the Gaseous Phase Based on Measuring PVT-Properties of 1,1,1-Trifluoroethane (R143a)

For a reliable derivation of the thermodynamic properties in the gaseous phase from thermodynamic equations of state, it has been pointed out that third virial coefficients significantly affect calculations of heat capacities. Among existing equations of state including internationally accepted equations, there is a large discrepancy, sometimes more than 5%, in calculated heat-capacity values near saturation. Two different approaches have been conducted in addressing this problem. One is for providing the third virial coefficient from intermolecular-potential models based on speed-of-sound measurements with a spherical resonator, and another is for confirming the effect of the third virial coefficient on density values near saturation by measuring the density precisely with a magnetic suspension densimeter. This report is focused on the latter case, i.e., precise measurements of density for 1,1,1-trifluoroethane, R143a, near saturation and some important evidence for the necessity of considering third virial coefficients for calculating reliable thermodynamic properties in the gaseous phase.Paper presented at the Seventh Asian Thermophysical Properties Conference, August 23–28, 2004, Hefei and Huangshan, Anhui, P. R. China.     

Size Distribution of Gold Nanoparticles Used by Small Angle X-ray Scattering

The size distribution of gold nanoparticles was estimated based on the scattering intensity data obtained from small angle X-ray scattering (SAXS) and compared with the result of micrographs by transmission electron microscopy. The slope of the Guinier plot was used to estimate the mean size assuming a narrow particle size distribution. When the size distribution is narrow, the mean size can be easily obtained from slope of a Guinier plot of scattering data within 10% error. Additionally, assuming a lognormal size distribution, the size distribution and the mean size can be calculated using the experimental SAXS data in the fitting analysis. The histogram method, which utilizes the coefficient matrix of scattering intensity, was also applied to the estimation of the size distribution, and this method could be useful for a rough estimate of the size distribution.     

飞机训练模拟器视景系统非线性失真校正技术研究

柱面实像投影是飞机训练模拟器视景系统采用的主要投影方式之一,可以得到很大的观察视野,但是不可避免地会产生非线性失真。根据具体的工程背景,针对大视场角的柱面实像投影的非线性失真,分析了其产生的原因,并设计了投影仪的离轴安装方案,从而提出了基于预失真的柱面投影非线性失真校正算法。实际的校正结果表明,采用预失真的方法进行柱面非线性失真校正,是一种行之有效的方法。通过相应的数据结构设计,保证了程序执行的实时性。