Janus metasurface holography with asymmetric transmission characteristics provides new degrees of freedom for multiplexing technologies. However, earlier metasurfaces with asymmetrical transmission faced limitations in terms of tunability and multifunctionality. In this study, we propose a metasurface color holographic encryption scheme with dynamic switching and asymmetric transmission at visible frequencies using a low-loss nonvolatile optical phase-change material, Sb2S3. Using a modified holographic optimization strategy, we achieved high-fidelity asymmetric holographic imaging of a nanostructured metasurface. By controlling the incident direction and wavelength of visible light, as well as the level of crystallization of Sb2S3, this reconfigurable metasurface enables the precise manipulation of tunable color holographic image displays. In particular, in the semi-crystalline state of Sb2S3, the encoded information can be securely encrypted using a two-channel color-holographic image, whereas only a preset camouflaged image is displayed in the crystalline or amorphous state of Sb2S3. The proposed multiencrypted Janus metasurface provides a potential approach for dynamic holographic displays with ultrahigh capacity, holographic encryption, and information storage.

Radio frequency/microwave-directed energy sources using wide bandgap SiC photoconductive semiconductors have attracted much attention due to their unique advantages of high-power output and multi-parameter adjustable ability. Over the past several years, benefitting from the sustainable innovations in laser technology and the significant progress in materials technology, megawatt-class output power electrical pulses with a flexible frequency in the P and L microwave wavebands have been achieved by photoconductive semiconductor devices. Here, we mainly summarize and review the recent progress of the high-power photonic microwave generation based on the SiC photoconductive semiconductor devices in the linear modulation mode, including the mechanism, system architecture, critical technology, and experimental demonstration of the proposed high-power photonic microwave sources. The outlooks and challenges for the future of multi-channel power synthesis development of higher power photonic microwave using wide bandgap photoconductors are also discussed.

针对高光谱影像分类方法精度不足的问题，提出一种基于空间-频谱变换（Spectral-Spatial Transformer，SST）网络的高光谱影像分类方法。首先，将高光谱影像预处理为一维特征向量。然后，设计了具有光谱-空间注意力模块和池化残差模块的SST高光谱影像分类网络。本文所提出的分类方法在Indian Pines数据集和Pavia University数据集上的总体分类精度分别为98.67%和99.87%，表明此方法具有较高的分类精度，为高光谱影像分类及应用提供了一种新方案。

反应堆发生严重事故后，将堆芯熔融物滞留在压力容器内的策略（In-vessel Retention，IVR）是作为缓解严重事故的一项重要措施，该策略已成功应用于AP1000、华龙一号和CAP1400等先进压水堆的严重事故管理中。在实施IVR策略时，下封头受到高温熔融物的热负荷会发生变形，下封头的变形改变堆腔的冷却流道，这会直接影响压力容器外部冷却的排热能力和IVR策略的成功实施，有必要对下封头变形展开研究和应用。针对ISAA（Integrated Severe Accident Analysis）程序LHTCM（Lower Head Thermal Creep Module）模型简化薄膜应力模型十分简单和缺乏计算变形模块的问题，本文从机理出发，基于Timoshenko板壳理论、Nortron蠕变定律和大变形塑性理论开发了机理模型—下封头大变形模型，并将该模型集成到一体化严重事故分析程序ISAA中对FOREVER-EC2实验进行应用，预测失效时间与实验的误差仅为1.9%，预测底部伸长量与实验测量值较为符合，破口位置与实验一致。分析结果表明该模型能准确预测在堆芯熔化严重事故中下封头所受应力、失效时间、整体形变和破口位置。

采用坩埚下降法生长了NaI∶Zn（0，0.05%，0.08%，0.4%），Tl（0.18%）晶体。对晶体样品进行了X射线粉末衍射、电感耦合等离子体发射光谱以及紫外可见近红外透射光谱测试。结果表明，生长的晶体具有单一的物相，Zn和Tl离子掺杂并没有改变NaI的晶体结构；随着Zn掺杂浓度的增加，晶体内的Zn²⁺离子浓度增加、Tl⁺离子浓度下降；晶体透过率随Zn掺杂浓度的增加呈现先增大后减小的趋势，Zn掺杂浓度为0.08%时，样品的透过率最高，且所有样品在350~700 nm波段的透过率均高于70%。经过切割、打磨、抛光、封装等工序将NaI∶Zn，Tl晶体封装成辐射探测元件。闪烁性能测试结果表明，在¹³⁷Cs放射源激发下，Zn掺量为0.05%、0.08%时的NaI∶Zn，Tl晶体的能量分辨率≤6.80%，光输出相对于NaI∶Tl晶体增加6%~10%，这有利于NaI晶体在高能粒子探测领域的进一步应用。