水下双层圆柱壳体结构辐射噪声实时预报方法研究

根据Sommerfeld辐射条件和统计能量假设定义了具有方向性特征的声辐射系数,再结合声辐射效率特性定义了新的参数声辐射因子。在外壳体表面速度实时重构理论基础上提出了用声辐射因子实现水下双层圆柱壳体结构辐射噪声实时预报的方法,还提出了有限长水下圆柱壳体结构声辐射因子的试验测量方法。水下声学试验研究表明该方法预报的辐射声压与实测值吻合较好,能满足水下噪声预报的实时性、远场指向性和工况适应性等计算要求。      

矩形法兰孔孔口模态辐射阻抗的计算与分析*

针对半空间矩形法兰孔孔口模态辐射阻抗计算困难的问题,提出一种模态辐射阻抗的计算方法。该方法通过坐标变换将四重积分转换为二重积分并消除奇异积分,且将这一系列过程通过MATLAB内置函数直接实现,显著降低了模态辐射阻抗计算的复杂程度。通过对比与分析,验证了该方法的正确性,得到了自模态辐射阻抗随模态阶次增加峰值逐渐往高频移动且呈减小趋势、互模态辐射阻抗相比于自模态辐射阻抗小到可以忽略不计的性质。     

辐射换热的输运模拟研究

本文从辐时与传输的基本原理出发，引进辐射推动力及流热参数的概念，建立了一般情况下辐射传热的二阶微分方程的数学模型。该方程具有传输方程的特点，使得辐射传热的处理在方法上与导热、流动问题相一致。     

表面辐射测温方法的设计原理

讨论了表面辐射测温方法的设计中所包含的几个基本问题:辐射的光谱和方向复杂性问题、光学设计问题以及电路设计问题,给出了具有普适意义的辐射测温基本分析式。比较了绝对辐射测温方法和相对辐射测温方法,指出前者须做标定,并且不宜进行温度场测量;后者无须标定,适合于温度场测量。     

基于扩散近似法和双通量法耦合的多孔介质内燃烧辐射换热计算方法

将Rosseland辐射模型和双通量法结合,对瓦斯气体在泡沫陶瓷中预混燃烧辐射换热计算方法进行研究.数值模拟的结果与试验结果吻合比较好,证明提出的辐射换热计算方法是有效的.     

水下环境光学特性测量方法

为实现水下对航行器光学探测,研究了水下环境光学特性测量机理,确立了海洋下行辐射、海洋上行辐射测量方法。在分析海洋下行辐射分布规律的基础上,简化了海洋下行辐射模型,建立了Janus海洋下行辐照度测量模型,设计了辐照度光学探头,确定了海洋上行辐射测量方法,并完成光学探头的响应度定标设计。分析表明,下行辐照度由标量辐照度、散射系数、体积衰减系数和漫衰减系数共同决定,均匀角分布入射辐射率,当入射角小于70°时,余弦误差小于5%,采用的Janus设计优化了海洋下行辐照度的测量。海洋下行辐射、海洋上行辐射测量方法的建立,为水下实现目标环境光学特性测量奠定了技术理论支撑。     

On the eikonal approximation in the theory of transition radiation

The transition radiation of relativistic electrons in nonuniform media is considered. Based on the equivalent photon method and the eikonal approximation in wave mechanics, a method for describing this process is proposed. For the case in which the permittivity depends on several coordinates, equations for the spectral-angular density of transition radiation are obtained. The main results obtained in the Born and eikonal approximations of the theory of transition radiation are compared. The equations obtained are used to analyze the transition radiation process for a fiberlike target.     

Heterodyne detection of synchrotron radiation

A time integral method for the study of resonant nuclear scattering of synchrotron radiation in the forward direction is presented. The method relies on the interference of radiation scattered by nuclei in two samples, one moving with respect to the other. The method, termed heterodyne detection of synchrotron radiation, gives the same information on hyperfine parameters as the well known differential method. The general formalism is developed for the case where the reference is a single line sample and the investigated sample has magnetic or quadrupole splitting. The first experiments are discussed. A comparison of time differential synchrotron radiation spectroscopy, heterodyne detection and Mössbauer spectroscopy is given.     

Speckle polarization diagnostics of scattering media using partially coherent radiation

The paper discusses a method for probing a randomly inhomogeneous medium using partially coherent radiation and polarization filtering of the radiation scattered by the medium. The method is based on the analysis of the contrast of speckle-modulated images of the object under study as a function of the coherence length of the probe radiation. A theoretical justification of the method is given as applied to systems of discrete scatterers with the subsequent modification of the results obtained for continuously distributed scattering systems. The results of experimental testing of the developed method for scattering media characterized by nondiffusion conditions of propagation of the probe radiation are presented and compared with the results of the theoretical analysis.     

星载多波段红外光学系统的杂散辐射分析

引入反向蒙特卡罗法与双向蒙特卡罗法对红外光学系统的杂散辐射进行分析,基于光谱辐射传递因子导出了焦平面辐射能流计算式.以某星载多波段红外光学系统为例,在检验计算可靠性的基础上,模拟了各波段辐射能从地球背景和光机内壁面到焦平面的传播过程,分析了壁面吸收率与温度的影响.结果表明,采用双向蒙特卡罗法可有效地模拟辐射能从地球向星载光学系统焦平面的传播过程,采用反向蒙特卡罗法可容易地分析光机内部热辐射的影响;光机内壁面吸收率对视场外杂散辐射的传播有很大影响,温度高于250 K的光机内壁面热辐射成为主要的杂散光源.     

Study on CYCIAE-100 radiation field and residual radioactivity

The accelerators should be properly designed to make the radiation field produced by beam loss satisfy the dose limits. The radiation field for high intensity H- cyclotron includes prompt radiation and residual radiation field. The induced radioactivity in accelerator components is the dominant source of occupational radiation exposure if the accelerator is well shielded. The source of radiation is the beam loss when cyclotron is operating. In this paper, the radiation field for CYCIAE-100 is calculated using Monte Carlo method and the radioactive contamination near stripping foil is studied. A method to reduce the dose equivalent rate of maintenance staff is also given.     

放射性同位素伽玛源准直照射辐射场模拟研究

针对各向同性伽玛源参考辐射场尺寸关键技术问题,GB/T 12162系列标准虽然进行了相关规定,但是该规定并未对准直照射状态下照射室尺寸提出具体要求。为减小用于辐射检测或监测类仪器仪表检定与量值校准时伽玛参考辐射场内散射影响,本文采用蒙特卡罗方法,研究了同位素放射源准直照射时,照射室尺寸变化对检验点处的剂量率值与能量分布的影响情况,获得了准直照射时伽玛辐射场照射室尺寸的边界条件,建立并完善了伽玛参考辐射场边界研究方法及相关标准细节,为准直照射状态下照射室尺寸设计提供了一种新方法或途径。     

圆柱壳体瞬态辐射噪声评估算法

通过自身传感器实测振动数据快速评估瞬态辐射噪声,对及时排除故障,保持水下目标隐蔽性具有重要的意义。本文提出一种基于加速度阵列测试数据的圆柱壳体瞬态辐射声场的工程估算方法:借鉴工况传递分析的思路,分析求解瞬态振-声传递率矩阵,将瞬态激励壳体振动的测量数据代入,就可以估算壳体辐射声压级。在振-声传递率求解的过程中引入截断奇异值分解法,改善求逆时的病态矩阵,减少测试中背景干扰带来的估计误差。试验结果证实,该方法可以用来快速评估空气中敲击圆柱壳体所产生的瞬态辐射噪声,大部分频段噪声级估计误差在3 d B以内。本方法可望提供快速估计圆柱形壳体振动水下辐射噪声级借鉴和参考。     

On the correctness of the thermoluminescent high-temperature ratio (HTR) method for estimating ionization density effects in mixed radiation fields

The high-temperature ratio (HTR) method which exploits changes in the LiF:Mg,Ti glow-curve due to high-LET radiation, has been used for several years to estimate LET in an unknown radiation field. As TL efficiency is known to decrease after doses of densely ionizing radiation, a LET estimate is used to correct the TLD-measured values of dose. The HTR method is purely empirical and its general correctness is questionable. The validity of the HTR method was investigated by theoretical simulation of various mixed radiation fields.The LET_eff values estimated with the HTR method for mixed radiation fields were found in general to be incorrect, in some cases underestimating the true values of dose-averaged LET by an order of magnitude. The method produced correct estimates of average LET only in cases of almost mono-energetic fields (i.e. in non-mixed radiation conditions). The value of LET_eff found by the HTR method may therefore be treated as a qualitative indicator of increased LET, but not as a quantitative estimator of average LET.However, HTR-based correction of the TLD-measured dose value (HTR-B method) was found to be quite reliable. In all cases studied, application of this technique improved the result. Most of the measured doses fell within 10% of the true values. A further empirical improvement to the method is proposed. One may therefore recommend the HTR-B method to correct for decreased TL efficiency in mixed high-LET fields.     

利用LBH辐射图像数据反演大气O/N2方法

利用极光Lyman-Birge-Hopfield (LBH) 辐射图像数据可用来研究太阳风磁场与地球磁场耦合、亚暴与磁暴等过程,综合LBH辐射图像数据和O原子135.6nm辐射数据可反演电离层氧原子与氮气分子O/N2比值分布,进而研究高层大气组分信息及电离层分布变化,对科学研究和空间天气预报具有重要意义. 本文给出了LBH辐射传输机理和我国自主研制的搭载在风云三号D星（FY-3D）上的广角极光成像仪（Wide-field Auroral Imager, WAI）在轨获得的LBH 140-180nm波段极光辐射图像数据. 结合大气紫外辐射积分代码（Atmospheric Ultraviolet Radiance Integrated Code, AURIC）计算O135.6nm辐射数据、LBH辐射光谱以及MSISE00大气模型计算的O、N2数据,给出了利用WAI观测的LBH辐射图像数据反演大气O/N2比值理论计算方法,该方法将为利用我国自主观测LBH辐射数据和O135.6nm辐射数据开展空间信息反演研究打下基础.     

屏蔽两芯线BCI等效替代辐照理论模型研究

针对大范围空间模拟强场电磁环境进行辐射效应试验难度大以及现有大电流注入（BCI）技术应用于非线性系统试验存在空白的问题,开展了屏蔽线耦合通道BCI等效替代辐照试验方法研究。以受试设备响应相等作为等效依据,建立了辐照法和注入法两种条件下受试设备响应的分析模型,推导出了注入激励源电压与辐照场强之间的等效对应关系,提出了BCI等效替代辐照的条件和试验方法,并进行了试验验证。研究结果表明,BCI方法是可以精确等效受试设备的辐照效应试验,试验误差不超过2 dB,能够满足工程的实际需求。     

复杂结构声辐射模态的计算

结构辐射阻矩阵的特征向量就是其声辐射模态,复杂结构的辐射阻矩阵获取困难阻碍了声辐射模态理论的进一步应用。为此提出一种基于等效源方法的复杂结构辐射阻矩阵计算方法,由此形成了一套完整的计算复杂结构声辐射模态方法。最后通过仿真算例对影响结构辐射阻矩阵计算精度的因素进行了分析,给出了复杂结构辐射阻矩阵构造的一般原则。理论推导和数值仿真算例表明所提出的复杂结构声辐射模态计算方法是有效的。该方法简化了复杂结构声辐射模态的计算,计算效率较高。     

A real-time infrared radiation imaging simulation method of aircraft skin with aerodynamic heating effect

Real-time infrared radiation simulation technology can provide effective support for rapid design and evaluation of a system which integrates infrared imaging technology. Considering the aerodynamic heating effect, this paper presents a real-time infrared radiation characteristic simulation method of aircraft skin based on the panel element method, which can help to assess the infrared radiation impacts of different environment factors and materials. A 3-D model of an aircraft was established and its surface was divided into different parts and panel element meshes to attach material properties. For each mesh, its heat exchange equation is solved so as to obtain the whole skin’s temperature and infrared radiation distribution. The simulation results reveal the influence of different factors on the skin surface radiation, including environmental radiation, aerodynamic heating and material properties. And the credibility and efficiency of the proposed aerodynamic heating simulation method were confirmed by comparing to the CFD simulation results.     

DRESOR法对瞬态辐射传递问题的研究

用基于蒙特卡洛法(Monte Carlo Method,MCM)的DRESOR法(Distributions of Ratios of Energy Scattered by the medium Or Reflected by the boundary surface)求解入射辐射经过介质散射、壁面反射传递后辐射强度随时间变化的瞬态辐射传递方程(Transient RadiativeTransfer Equation,TRTE)问题。通过在系统内计算一单位瞬态入射辐射对介质的DRESOR数分布,就能计算任意时间内入射辐射在系统内时间响应特性,这样有效提高数值方法处理瞬态辐射问题的通用性。并且能够获得高方向分辨率的辐射强度随时间变化的结果,这是目前大多数数值处理方法比较难做到的,显示出了DRESOR法处理瞬态入射辐射问题的能力．     

弯轨Čerenkov辐射计算中的稳相法

从介质中沿弯曲轨道运动的带电粒子辐射的频谱角分布公式出发, 分析了粒子速度大于介质中的光速时, 稳相点在?erenkov效应中所起的关键作用, 并给出了通过在稳相点附近做渐近展开来计算弯轨?erenkov辐射的稳相法. 运用稳相法, 计算了同步?erenkov辐射在粒子轨道平面附近以及在临界角附近的频谱角分布. 计算结果表明, 同步?erenkov辐射频谱的特征依赖于观测方向附近对应的稳相点性状, 特别是在较大的临界角附近的频谱与小角度近似时很不相同. 关键词： ?erenkov效应 稳相点 稳相法 同步?erenkov辐射