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101.
Xiang-Yang Wang Pan-Pan Niu Hong-Ying Yang 《Multimedia, IEEE》2009,16(3):60-69
Most of the previous audio-watermarking schemes are robust to common signal-processing attacks, but show severe problems when faced with desynchronization attacks. To solve the problems associated with these approaches, we propose an audio-watermarking scheme based on support-vector-machine (SVM) theory to protect against desynchronization attacks by using audio statistics characteristics and a synchronization code technique. Experimental results with SVM show that our proposed scheme is inaudible, robust against common signal processing, and robust against desynchronization attacks. 相似文献
102.
103.
各极化通道独立处理和三维分步成像会忽视数据之间的关联性,造成散射中心的失配以及极化散射矩阵获取的不准确。鉴于此,该文提出一种基于稀疏重构的全极化联合多维重建方法。该方法通过设置联合稀疏约束对所有极化通道及所有维度进行联合,将全极化多维重建建模为多通道联合稀疏重构问题。通过数据插值对模型简化后,结合三维快速傅里叶变换、共轭梯度法和牛顿迭代法给出一种高效的模型求解方法,可以同时得到极化散射矩阵和目标三维信息。该文方法保证了不同极化通道、不同维度的稀疏支撑集一致,且充分利用了数据之间的关联性带来的额外信息。基于仿真数据和电磁计算数据的实验结果表明,该方法的性能不受目标类型影响,具有一定的抗噪性,能有效地获取目标的多维重建结果,得到的三维成像结果分辨率高且极化散射矩阵估计精度高。 相似文献
104.
105.
106.
We report on room temperature continuous-wave optically pumped InAs/GaAs quantum dot whispering gallery mode microdisk lasers,heterogeneously integrated on silica/silicon chips.The microdisks are fabricated by photolithography and inductively coupled plasma etching.The lasing wavelength is approximately 1200 nm and the obtained lowest laser threshold is approximately 28μW.The experimental results show an approach of possible integrated Ⅲ-Ⅴ optical active materials on silica/silicon chip for low threshold WGM microdisk lasers. 相似文献
107.
Sisi Liu Chongjian Zhang Shuangyuan Li Yong Xia Kang Wang Kao Xiong Haodong Tang Linyuan Lian Xinxing Liu Ming-Yu Li Manlin Tan Liang Gao Guangda Niu Huan Liu Haisheng Song Daoli Zhang Jianbo Gao Xinzheng Lan Kai Wang Xiao Wei Sun Ye Yang Jiang Tang Jianbing Zhang 《Advanced functional materials》2021,31(9):2006864
Lead chalcogenide quantum dot (QD) infrared (IR) solar cells are promising devices for breaking through the theoretical efficiency limit of single-junction solar cells by harvesting the low-energy IR photons that cannot be utilized by common devices. However, the device performance of QD IR photovoltaic is limited by the restrictive relation between open-circuit voltages (VOC) and short circuit current densities (JSC), caused by the contradiction between surface passivation and electronic coupling of QD solids. Here, a strategy is developed to decouple this restriction via epitaxially coating a thin PbS shell over the PbSe QDs (PbSe/PbS QDs) combined with in situ halide passivation. The strong electronic coupling from the PbSe core gives rise to significant carrier delocalization, which guarantees effective carrier transport. Benefited from the protection of PbS shell and in situ halide passivation, excellent trap-state control of QDs is eventually achieved after the ligand exchange. By a fine control of the PbS shell thickness, outstanding IR JSC of 6.38 mA cm−2 and IR VOC of 0.347 V are simultaneously achieved under the 1100 nm-filtered solar illumination, providing a new route to unfreeze the trade-off between VOC and JSC limited by the photoactive layer with a given bandgap. 相似文献
108.
入射光椭圆度对晶体微粒旋转角速度的影响 总被引:1,自引:0,他引:1
光致旋转技术在微机械和微生物等领域的应用越来越广泛。利用光束自旋角动量可以导致晶体微粒光致旋转的机理,从理论上分析了入射光椭圆度对晶体微粒旋转角速度的影响。通过MATLAB对不同激光功率下,光束的椭圆度与晶体微粒旋转角速度的关系进行数值模拟。结果表明:在实际对晶体微粒光致旋转操作中,晶体微粒能否旋转起来取决于光束椭圆度与微粒厚度之间的关系;在同一激光功率下,光束椭圆度与晶体微粒旋转角速度呈正旋曲线变化。因此,通过调节光束的椭圆度和较高的激光功率可以提高晶体微粒的旋转角速度。该结论对光驱动微机械马达的优化设计有一定的指导意义。 相似文献
109.
Yu Zhang Qian Zhou Jixin Zhu Qingyu Yan Shi Xue Dou Wenping Sun 《Advanced functional materials》2017,27(35)
Energy storage and conversion technologies are vital to the efficient utilization of sustainable renewable energy sources. Rechargeable lithium‐ion batteries (LIBs) and the emerging sodium‐ion batteries (SIBs) are considered as two of the most promising energy storage devices, and electrocatalysis processes play critical roles in energy conversion techniques that achieve mutual transformation between renewable electricity and chemical energies. It has been demonstrated that nanostructured metal chalcogenides including metal sulfides and metal selenides show great potential for efficient energy storage and conversion due to their unique physicochemical properties. In this feature article, the recent research progress on nanostructured metal sulfides and metal selenides for application in SIBs/LIBs and hydrogen/oxygen electrocatalysis (hydrogen evolution reaction, oxygen evolution reaction, and oxygen reduction reaction) is summarized and discussed. The corresponding electrochemical mechanisms, critical issues, and effective strategies towards performance improvement are presented. Finally, the remaining challenges and perspectives for the future development of metal chalcogenides in the energy research field are proposed. 相似文献
110.
In this paper, we develop and validate a method to identify computationally efficient site- and patient-specific models of ultrasound thermal therapies from MR thermal images. The models of the specific absorption rate of the transduced energy and the temperature response of the therapy target are identified in the reduced basis of proper orthogonal decomposition of thermal images, acquired in response to a mild thermal test excitation. The method permits dynamic reidentification of the treatment models during the therapy by recursively utilizing newly acquired images. Such adaptation is particularly important during high-temperature therapies, which are known to substantially and rapidly change tissue properties and blood perfusion. The developed theory was validated for the case of focused ultrasound heating of a tissue phantom. The experimental and computational results indicate that the developed approach produces accurate low-dimensional treatment models despite temporal and spatial noises in MR images and slow image acquisition rate. 相似文献