高速再入体热辐射模型的分析与修正

通过对现有高速再入体热辐射模型的分析计算,确立了目标的本体辐射、激波层辐射和尾流辐射之间的定量关系,从而建立了其修正的热辐射模型.将修正模型的理论计算结果、外场实测结果与实验室缩比模型仿真结果进行分析与比较,得出结论:高速再入体再入大气层时的热辐射模型采用本体辐射、激波层辐射和尾流辐射的修正模型,能更好地反映目标再入时的实际辐射,可以为目标热设计提供更准确的依据.     

用于太阳电池测试的太阳模拟技术

为了提高太阳模拟器的性能,更准确地测试太阳电池的特性参数,对模拟器的光源辐照利用率、辐照均匀度、辐照度与辐照稳定性的控制进行了研究.选取同轴光学系统结构作为模拟器光学系统,通过改进光学系统的结构排布,增加光积分器等方法,改善光源辐照利用率与辐照均匀度;在分析现役模拟器控制线路的基础上,采用光反馈技术对控制线路进行重新设计,提升系统对辐照度与辐照稳定性的可控性.实验结果表明:新型的太阳模拟器能有效地控制辐照度与辐照稳定性,在直径250 mm范围内,标准光强为1000 W/m2的条件下,辐照均匀度为2.5%,辐照稳定性＜1%,较大地改进了太阳模拟器的性能.     

碳纤维电热元件辐射强度分布的数值模拟

建立碳纤维电热辐射管辐射强度分布的数学模型,基于MATLAB软件模拟不同类型碳纤维电热元件的辐射强度分布,并讨论其空间辐射特性。模拟结果表明：结构参数对碳纤维电热元件辐射强度分布的影响较大,随管径的变化,空间辐射强度存在一个最佳值,辐射强度分布的不均匀性随管径的增加而增加。对比不同类型电热元件的辐射强度分布特性,相同规格电热元件的辐射强度分布场基本一致,而辐射强度值随元件类型而变化。碳纤维电热元件的辐射强度明显高于普通金属加热元件,并且双侧涂覆红外涂料可使其辐射强度明显地提高。调整涂料的配方可以改变红外辐射的频谱分布以满足特殊的加热要求。试验证明：测试数据与模拟结果基本一致,为后期辐射场的设计提供了依据。     

净全辐射表灵敏度测试方法研究

净全辐射表是测量太阳与大气向下发射的全辐射和地面向上发射的全辐射之差值的仪器,它的灵敏度可用二台长波辐射表和二台短波辐射表来测试.     

新型成型毛细管辐射板传热性能试验研究

简要介绍了新型成型毛细管辐射板的构造及制作方法,测试了2种不同形式辐射板的传热性能,分析了水流量、进水温度、室温对加热管辐射板、毛细管辐射板供冷量的影响,得到了2种不同形式辐射板在制冷和供热工况下的表面温度分布情况,为新型成型毛细管辐射板的实际应用提供了参考依据。     

基于光谱的激光—MAG复合焊耦合机理分析

采用光纤式光谱仪,对激光—MAG复合焊等离子体辐射,进行空间分布200～1100nm间光谱采集。选取特定谱段辐射积分,给出其在紫外辐射(FeII)、可见光辐射(FeI)、红外辐射(ArI)各扫描层面辐射强度分布。进一步结合高速摄像,研究激光—MAG复合焊的耦合机理。研究结果表明,激光与MAG复合后,其等离子体在焊接电弧中心位置的辐射增强(其中紫外和可见光谱段更明显),形成一个辐射梯度较大的辐射增强区。FeI、FeII对应谱段的电弧辐射区间增宽,这种现象在激光作用的电弧前沿更明显。特定谱段辐射的面分布表明,激光—MAG耦合后,辐射在熔池附近及电弧中部的辐射增强,而在电弧上部的辐射减弱。耦合后的等离子体能量分布更集中于中心部位和熔池附近,复合等离子体Fe辐射区间的增宽,也为电弧稳定提供电离通道。耦合后等离子体辐射分布,使得激光复合焊焊缝成形改善、电弧稳定性增加。     

太阳辐射对汽车舱内热环境舒适性的影响研究与改善

太阳辐射是夏季炎热环境下汽车停放在户外汽车舱内热环境最大的热负荷,严重影响车内热环境及乘员热舒适性。运用商用FLUENT软件数值模拟太阳辐射对汽车舱内热环境舒适性的影响,仿真分析研究在没有太阳辐射及不同太阳辐射强度情况下车内热环境的变化,确定太阳辐射对车内热环境舒适性影响大。最后通过降低车窗玻璃的透射率来减少太阳辐射进入车内,达到了改善车内热环境舒适性的目的。     

空间碎片的红外探测研究

分析了空间碎片在轨运行时的空间辐射环境,通过分析空间碎片受到太阳、地球、月球等辐射的情况,计算其温度变化情况,并计算了8～12μm波段空间碎片的辐射情况。分析了红外探测器的噪声来源与类型,并计算了探测器接收的空间碎片红外辐射以及光学近场辐射所产生的电子数,然后分别计算了在目标温度不变与光学系统温度不变的情况下的信噪比(SNR)。结果显示,在以深空为探测背景的情况下,光学系统近场辐射是对系统探测距离影响最大的辐射。     

RESONANCE RADIATION OF SUBMERGED INFINITE CYLINDRICAL SHELL

The resonance sound radiation from submerged infinite elastic cylindrical shell, excited by internal harmonic line force, is investigated. The shell radiation power is presented in terms of resonant modal radiation derived from resonance radiation theory (RRT). The resonance radiation formulae are derived from classical Rayleigh normal mode solution, which are useful for understanding the mechanism of sound radiation from submerged shells. As an example, numerical calculation of a thin steel cylindrical shell is done by using these two methods. It seems that the results of RRT solutions are in good agreement with that of Rayleigh normal mode solutions.     

A radio-frequency impedance spectroscope for studying interaction of high-power laser radiation with crystals

A radio-frequency impedance spectroscope for studying the interaction of high-power laser radiation with nonlinear optical crystals has been developed. It has been revealed that the shape of the piezoelectric resonance line of a crystal heated with laser radiation is identical under both uniform heating in the absence of laser radiation and nonuniform heating resulting from the action of laser radiation. This allows introduction of the notion of the equivalent crystal temperature characterizing the nonuniform temperature distribution in a crystal exposed to laser radiation.     

氟化镁窗口氘灯的真空辐射衰减特性

针对真空环境下使用氟化镁窗口氘灯时,氘灯表面易受污染,导致氘灯的紫外-真空紫外辐射强度逐渐衰减的问题,对紫外-真空紫外波段辐射传递标准光源氘灯的真空辐射衰减机理进行了分析.在此基础上,研制了液氮制冷屏装置来抑制氘灯衰减.建立了氘灯真空辐射特性测试系统,利用该系统对液氮制冷屏装置的有效性进行了考察.测试结果显示,在160～300 nm波段,氘灯平均衰减率可由原来的7%/h下降为1%/h,表明液氮制冷屏装置能有效地抑制氟化镁窗口氘灯在真空环境下的辐射衰减.     

基于深度学习的射频电路空间辐射测试系统

针对射频电路及天线的辐射性能测试需求,提出一种基于机器学习的射频电路空间辐射OTA测试系统。系统引入深度学习方法,利用三维空间有限测量数据训练一个全连接深度神经网络(FCDNN)模型,从而估计被测射频电路系统在三维空间各个方向上的辐射性能。为了权衡训练FCDNN模型所需的测试点数量与模型预测结果的准确度,进一步提出动态检验模型准确度,逐步提升训练测试点数量,直到模型精度达到预设要求的解决办法。实验结果表明,相比于现有OTA测试系统,所提出的基于深度学习的测试系统只需约60%的测试点,就能精准重构被测射频电路的空间辐射性能,验证了该方案的准确性与高效性,为行业提供了一种精确却低成本的空间辐射测试技术解决方案。     

近场结构声辐射模态分析

为减小由瑞利积分计算结构声辐射功率的复杂性及结构振动模态声辐射耦合对辐射效率的影响,提出以有限离散思想为基础的结构近场声辐射模态分析方法,该方法对结构辐射表面进行离散化,利用叠加原理建立近场声辐射模态模型和辐射声功率的计算公式。以简支板为例,利用有限元和边界元法对近场结构声辐射进行仿真分析,计算了结构声辐射模态,辐射效率,声功率及场点声压等声场特性参数,并讨论了不同力作用位置对结构声辐射的影响,得到了简支板结构在简谐激励力作用下的近场声辐射特性。该分析对复杂结构声的近场声辐射仿真计算和主动控制有重要指导意义。     

压缩机机体声辐射的模态特性研究

采用有限元和边界元方法建立了轻流体介质中复杂结构振动声辐射的模态分析模型,可计算结构的声辐射模态频率、模态场点声压、模态辐射声功率和声辐射效率等声场特性参数。对K5206NM压缩机机体进行了模态分析和声辐射模态参数计算,获得了机体的声辐射特性,从而为机体的低噪声设计提供了依据。     

Calculation of the depth distribution function for continuous radiation

A newly developed electron-scattering model has been employed for calculating depth distribution functions for bremsstrahlung. A comparison with depth distribution functions used in connection with characteristic radiation reveals that the value of the surface radiation Φ(0) is comparatively smaller in cases of continuous radiation generation, while the centre of gravity of the bremsstrahlung curves is situated at larger mass depths, thus increasing the effect of radiation absorption phenomena. The discrepancies between both types of curves increase with decreases in atomic number and overvoltage ratio. In light of the present results the transformations of characteristic radiation curves for obtaining those for continuous radiation known so far are not likely to be physically realistic. Therefore, the principle of a new transformation is proposed.     

Study on the general characteristics of the sound radiation of a rectangular plate with different boundary edge conditions

Sound radiation is the most important phenomenon when a structure vibrates, which is strongly dependent on boundary conditions and its shape such as aspect ratio. This paper deals with general aspects of sound radiation from this viewpoint. A particular guided and pinned condition being taken into account here, is that the cross-modal terms can average out for all possible point excitation locations. Then, the average radiation efficiency based on the modal radiation efficiency and corresponding radiation power can numerically be obtained. It is shown that the radiation power of the guided plate is governed by the piston mode as well as the critical frequency. Unlike the pinned plate, no clear corner and edge mode regions below the critical frequency may be found for the guided case. Meanwhile, if the plate damping increases the similar tendency that the radiation efficiency increases below the critical frequency is found, as the vibrational level decreases. For the strip with a large aspect ratio, the radiation power is maximised at frequencies where the wavelength is an integer times the short edge length. This can be seen for both the guided and the pinned boundary conditions.     

Design and implementation of automatic shading device for diffuse radiation measurement

Considering the problem of too large area the shading disc covered,complex shadow band coefficients and too big diffuse radiation measurement bias,an automatic shading device for diffuse radiometer is designed and realized. Set a shading ball on the automatic sun tracker,drive linkage parallelogram structure with the declination axis arm,the shading ball can rotate synchronously with the motion of the sun and shade beam radiation measured with pyranometer,thus shading beam radiation and measuring diffuse radiation can be realized automatically. The comparison test results show that the automatic shading device can realize diffuse radiation measurement automatically,the accuracy of diffuse radiation readings can get a 18. 7% improvement compared with traditional measure system,greatly improves the reliability and accuracy of the diffuse radiation measurement.     

Radiation Characteristics of Rectangular Patch Antennas with an Array of Pins

The patch antennas with an array of pins (pin array patch antennas) with excellent radiation characteristics are investigated for various substrate thicknesses.The radiation in the horizontal plane of a pin array patch antenna is very small campared to that of a conventional patch antenna.And the increase of forward radiation and the decrease of backward radiation of a pin array patch antenna are tained than these conventional one's.Also the half-power beamwidth of E-plane radiation pattern of a pin array patch antenna is narrower compared to that of the conventional so that the directivity is improved.     

基于PLC控制系统的抗电磁干扰对策分析

用PLC组成控制系统的抗电磁干扰对策问题,分析了电力网络空间辐射电磁场(EMI)等产生的辐射对PLC干扰.射频场内造成辐射干扰主要影响有两条路径:一是由电路感应产生干扰直接对PLC内部的辐射;二是由通信线路感应引入干扰对PLC通信网络的辐射.辐射干扰与现场设备的布置情况及设备所产生的电磁场大小与频率有关,一般采用设置屏蔽电缆和PLC局部屏蔽及高压泄放元件进行保护.     

应用标准进行雷达防太阳辐射的论证、设计与试验

介绍了太阳辐射的基本概念、能量分布情况和对军用地面雷达装备的影响,给出了论证军用地面雷达环境适应性时太阳辐射强度取值的依据、降低太阳辐射影响的措施和太阳辐射试验的参数取值依据与对试验设备的要求,可供从事环境适应性论证、设计与试验工作的人员参考。