坦克排烟的红外辐射计算及热图像仿真

为研究坦克排烟的红外辐射特性,建立了坦克排烟热流场数值计算模型,对流场分布进行分析和计算,得到了排烟的温度场分布。使用谱带模型C-G近似法,计算出排烟的辐射亮度,并进行热图像仿真。通过CO₂辐射亮度的计算值与实测值比较表明:该模型和方法能够得到较为准确的结果,可应用于坦克排烟的红外热图像仿真。     

Improving InGaN-LED performance by optimizing the patterned sapphire substrate shape

The epitaxial growths of GaN films and GaN-based LEDs on various patterned sapphire substrates (PSSes) with different values of fill factor (f) and slanted angle (θ) are investigated in detail. The threading dislocation (TD) density is lower in the film grown on the PSS with a smaller fill factor, resulting in a higher internal quantum efficiency (IQE). Also the ability of the LED to withstand the electrostatic discharge (ESD) increases as the fill factor decreases. The illumination output power of the LED is affected by both θ and f. It is found that the illumination output power of the LED grown on the PSS with a lower production of tanθ and f is higher than that with a higher production of tanθ and f.     

坦克动力舱体红外辐射特性模拟

建立了坦克动力舱体的温度场数值计算模型和红外特性计算模型,对坦克动力舱体的红外特性进行了理论计算,得到了辐射强度方向图。动力舱体红外特性的计算结果与试验结果的相对误差小于15.6%,基本满足工程设计的需要。研究结果表明,动力舱顶装甲板是主要辐射源,排气百叶窗和排气管附近顶装甲板是坦克的红外辐射特征明显区域。坦克动力舱体的红外辐射主要集中在8~12μm波段。     

Improving InGaN-LED performance by optimizing the patterned sapphire substrate shape

The epitaxial growths of GaN films and GaN-based LEDs on various patterned sapphire substrates(PSSes) with different values of fill factor(f) and slanted angle(θ) are investigated in detail.The threading dislocation(TD) density is lower in the film grown on the PSS with a smaller fill factor,resulting in a higher internal quantum efficiency(IQE).Also the ability of the LED to withstand the electrostatic discharge(ESD) increases as the fill factor decreases.The illumination output power of the LED is affected by both θ and f.It is found that the illumination output power of the LED grown on the PSS with a lower production of tan θ and f is higher than that with a higher production of tan θ and f.     

In组分对InGaN/GaN蓝光LED的发光性质的影响

利用扫描透射电子显微术(STEM)和变温光致发光光谱(PL)研究了In组分对InGaN/GaN蓝光LED的发光的影响.STEM发现两个样品量子阱结构相同,低温PL显示低In组分的样品的发光峰位随着温度的升高呈现出经典S(Red-Blue-Red)曲线.目前普遍认为蓝移是In组分分布不均匀造成的局域激子发光的主要原因,然...     

坦克动力舱体温度场数值仿真与实验验证

建立了坦克动力舱体温度场数值计算模型,采用流固耦合的计算方法计算车体壁面的温度场,应用壁面函数法修正处于流场内部的固壁,通过固体和流体双向耦合换热计算,并考虑太阳辐射对车体温度场的影响,得出了车体壁面温度场的分布.并将计算结果与测试结果进行了对比.研究结果表明,动力舱体温度场的计算结果与测试结果的相对误差小于9.034%,所使用的数值计算方法可用于动力舱体温度场的数值计算及分析,基本满足工程设计的需要.