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High quality above 3-μm mid-infrared InGaAsSb/AlGaInAsSb multiple-quantum well grown by molecular beam epitaxy 下载免费PDF全文
The GaSb-based laser shows its superiority in the 3–4 μm wavelength range. However, for a quantum well(QW) laser structure of InGaAsSb/AlGaInAsSb multiple-quantum well(MQW) grown on GaSb, uniform content and high compressive strain in InGaAsSb/AlGaInAsSb are not easy to control. In this paper, the influences of the growth temperature and compressive strain on the photoluminescence(PL) property of a 3.0-μm InGaAsSb/AlGaInAsSb MQW sample are analyzed to optimize the growth parameters. Comparisons among the PL spectra of the samples indicate that the In0.485GaAs0.184Sb/Al0.3Ga0.45In0.25As0.22Sb0.78MQW with 1.72% compressive strain grown at 460 C posseses the optimum optical property. Moreover, the wavelength range of the MQW structure is extended to 3.83 μm by optimizing the parameters. 相似文献
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Very long wavelength infrared focal plane arrays with 50% cutoff wavelength based on type-Ⅱ In As/GaSb superlattice 下载免费PDF全文
A very long wavelength infrared(VLWIR) focal plane array based on In As/Ga Sb type-Ⅱ super-lattices is demonstrated on a Ga Sb substrate. A hetero-structure photodiode was grown with a 50% cut-off wavelength of 15.2 μm, at 77 K.A 320×256 VLWIR focal plane array with this design was fabricated and characterized. The peak quantum efficiency without an antireflective coating was 25.74% at the reverse bias voltage of-20 mV, yielding a peak specific detectivity of 5.89×1010cm·Hz~(1/2)·W~(-1). The operability and the uniformity of response were 89% and 83.17%. The noise-equivalent temperature difference at 65 K exhibited a minimum at 21.4 mK, corresponding to an average value of 56.3 mK. 相似文献
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<正>This paper presents a robust output feedback control method for uncertain chaotic systems,which comprises a nonlinear inversion-based controller with a fuzzy robust compensator.The proposed controller eliminates the unknown nonlinear function by using a fuzzy system,whose inputs are not the state variables but feedback error signals.The underlying stability analysis as well as parameter update law design are carried out by using the Lyapunov-based technique.The proposed method indicates that the nonlinear inversion-based control approach can also be applied to uncertain chaotic systems.Theoretical results are illustrated through two simulation examples. 相似文献
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为解决THz行波管工作电流过小、输出功率低等问题,提出了基模多注工作模式的折叠波导行波管.首先,获得了基模多注折叠波导色散特性的等效传输线计算模型,并与数值模拟结果进行了比较;然后,对基模多注折叠波导的传输特性进行了模拟计算;最后,通过模拟和理论计算完成了0.14 THz基模多注折叠波导行波管的注波互作用特性分析.电子注参数为12 m A,15.75 k V时,获得的3 d B带宽为25 GHz(128—153 GHz),最大增益为33.61 d B,最大峰值功率为23 W;电子注参数为30 m A,15.75 k V时,在0.14 THz处获得了38 d B增益,最大脉冲输出功率为63.1 W.对比同条件下基模单注折叠波导行波管,3 d B带宽提升了1倍,0.14 THz处输出功率增大了9.66倍,互作用效率增大了3.22倍;当增益相同时,多注方式的互作用长度较单注缩短了33%.该方法能够有效增大THz行波管的工作电流,提高互作用增益及效率、3 d B带宽、输出功率;在增益相同时,基模多注行波管可以做得更短更紧凑. 相似文献
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为了提高THz行波管的输出功率,通过并行多注和功率合成的方法,完成了并行多注D波段折叠波导行波管的理论分析与数值模拟。计算结果表明:单束行波管在0.135~0.157THz频率区间具有很好的色散平坦度,3dB带宽为13GHz,0.14THz处获得了20.88dB的最大增益;多束合成行波管在0.14THz处获得了20.8dB的合成增益,3dB带宽区间合成效率不低于92%。数值模拟表明该方法很好地实现了多路放大信号的合成输出。并行多注行波管具有输出功率大、单束电流小、聚焦磁场低等优点,能够在低发射电流密度条件下实现大功率THz辐射。 相似文献
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针对辐射环境下核废料检测准确率低的问题,提出一种基于深度卷积神经网络的辐射环境下核废料检测算法Dense-Dilated-YOLO V3。实验结果表明,Dense-Dilated-YOLO V3在不增加参数的情况下扩大了网络感受野,也有效避免图像信息的损失,同时能够在核辐射环境下提取到更多的目标细节特征,对辐射环境下目标检测的准确率可达93.29%,比原算法提高5.53%,召回率可达91.73%,提高了8.28%,有效解决了复杂辐射环境下核废料检测准确率低的问题,为辐射环境下核废料检测提供了新的途径。 相似文献
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采用碳酸盐共沉淀与燃烧法相结合的方法制备得到了多孔微纳球形结构的富锂正极材料0.6Li2MnO3·0.4LiNi0.5Mn0.5O2。借助X射线衍射(XRD)分析、X射线光电子能谱(XPS)、扫描电镜(SEM)、透射电镜(TEM)、N2吸附-脱附和恒电流充放电测试研究了其晶体结构、微观形貌和电化学性能。结果表明该方法制备出的材料是由一次颗粒径约300 nm的小颗粒组成的多孔微纳球形结构,比表面积为13 m2·g-1,具有完善的α-NaFeO2层状结构(空间群为R3m)。电化学性能测试结果证实该材料具有优异的高容量、高循环稳定性和高倍率性能。在2.0~4.8 V,电流密度为0.1C、0.2C、0.5C、1C、3C、5C和10C时的放电比容量分别为:266、254、235、205、186、149和107 mAh·g-1;在0.5C下循环100次后,放电比容量仍为217 mAh·g-1(容量保持率为94%)。 相似文献