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A clear and interesting image of local total energy anomaly(EA) is depicted for a heavy rainfall event in this study.Before the convection development, it exhibits a positive local EA, implying local total energy(TE) experiences heaping up to prepare for the future system development. As the convection grows, it transforms into an opposite spatial modality with negative EA dominant, which means that the local TE is consumed to feed the convection growth in the middle and lower levels. The local total EA has consistent variation regular in intensity with severe weather system evolution. By utilizing the local TE budget equation in variable density fluid, the flux divergence of energy and its components are investigated, which could account for the local TE variation better. To relax the restriction and complexity introduced by identifying sporadic and alternative positive/negative signals of EA, the method taking the absolute-value operator on energy flux divergence is used to further simplify analyses. The derived characteristic signal of absolute EA is clearer and cleaner than before.Thus, the EA could be illustrated based on the active degree of energy supply/consumption in a generalized sense whatever positive or negative anomaly should be it, which could be used easily to identify and even predict the system development for operational application. Note that, although two sets of methodologies are used to define EA herein, they play absolutely different roles in nature throughout the whole context. For example, the taking-perturbation method provides a diagnostic tool to portray a preliminary sketch and to give sufficient necessity of this research, while tendency equation of local TE illuminates more predictive sense and accounts for future local EA related to following system evolution. Therefore, the latter could be a more effective tool to routine usage. 相似文献
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Si C半超结垂直双扩散金属氧化物半导体场效应管(VDMOSFET)相对于常规VDMOSFET在相同导通电阻下具有更大击穿电压.在N型外延层上进行离子注入形成半超结结构中的P柱是制造Si C半超结VDMOSFET的关键工艺.本文通过二维数值仿真研究了离子注入导致的电荷失配对4H-Si C超结和半超结VDMOSFET击穿电压的影响,在电荷失配程度为30%时出现半超结VDMOSFET的最大击穿电压.在本文的器件参数下,P柱浓度偏差导致击穿电压降低15%时,半超结VDMOSFET柱区浓度偏差范围相对于超结VDMOSFET可提高69.5%,这意味着半超结VDMOSFET对柱区离子注入的控制要求更低,工艺制造难度更低. 相似文献
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随着非制冷型热像仪工作时间的增长,其内部器件、机械结构所积累的热量越来越多,其温升所导致的热辐射势必会对热像仪的测温精度产生严重影响。因此,要实现热像仪的准确测温,必须对其内部的各温升影响因素进行相应的修正。本文通过对影响测温精度的镜筒辐射温度、探测器靶面温度以及热像仪工作累积时间三个因素进行评估和建模,并对其相互关系进行评价,根据数据模型对热像仪辐射测温值进行修正。结果表明,在实验室条件下,经过修正,非制冷型红外热像仪测温精度可控制在±1℃以内,其稳定性可控制在±0.5℃以内。修正后的温度结果基本不受内部温升的影响,有效的提高了非制冷测温型热像仪的稳定性、可重复性以及测温精度。 相似文献
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本文基于自适应混合控制研究了一类分数阶复值神经网络的投影同步.首先,在复数域上构造了一个新的分数阶微分不等式;然后,通过设计新的自适应混合控制器,利用分数阶Lyapunov引理和复变函数理论,得到了分数阶复值神经网络自适应投影同步的充分条件;最后,通过数值模拟验证了理论结果的有效性. 相似文献
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卤化物钙钛矿材料作为一种新型半导体材料,具有优异的光电转换特性、能级结构可调、易于加工、结构和尺寸以及形貌可调、改性后优异的生物相容性等优点,在医学检测传感器中具有广阔的应用前景。本综述讨论了钙钛矿材料在生物医学传感领域的研究进展,钙钛矿医学传感器能通过光电转换、全光转换、电催化等多种物理或化学机制实现传感,具有可灵活选择的器件结构、性能指标和信号传递方式,用于人体代谢物质、神经递质、癌症相关物质和药物等医学物质的检测。钙钛矿医学传感器将为未来的医工多学科融合提供新希望,加快医工融合发展。 相似文献
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针对传统透射式光学系统初始结构优化设计效率低、结构选取过度依赖经验等问题,提出了一种基于深度学习的透射式光学系统初始结构自动优化设计方法。通过监督训练学习公开光学镜头库中参考镜头的结构特征数据,构建基于光线追迹的无监督训练模型,提升深度神经网络(DNN)模型的泛化能力。通过训练生成的网络模型输出包含真实玻璃的光学系统的结构参数,从而实现透射式光学系统初始结构的自动优化设计。设计结果表明:利用该网络模型优化设计的光学系统初始结构在全视场、全谱段下的像面点斑半径与参考镜头接近,并且能够根据不同焦距要求分别设计出光学系统初始结构;所设计的1×106组初始结构的成功率优于96.403%,表明所提网络模型具有良好的泛化能力。 相似文献
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Yuhui Dong 《中国物理 B》2023,32(1):18507-018507
Benefiting from the excellent properties such as high photoluminescence quantum yield (PLQY), wide gamut range, and narrow emission linewidth, as well as low-temperature processability, metal halide perovskite quantum dots (QDs) have attracted wide attention from researchers. Despite tremendous progress has been made during the past several years, the commercialization of perovskite QDs-based LEDs (PeQLEDs) is still plagued by the instability. The ion migration in halide perovskites is recognized as the key factor causing the performance degradation of PeQLEDs. In this review, the elements species of ion migration, the effects of ion migration on device performance and stability, and effective strategies to hinder/mitigate ion migration in PeQLEDs are successively discussed. Finally, the forward insights on the future research are highlighted. 相似文献