针对传统波达方向(Direction of Arrival,DOA)估计方法在低信噪比、少快拍数条件下表现性能差甚至失效的问题,提出了一种基于重构频域协方差矩阵的波达方位估计方法。该方法根据转化的频域信号进行共轭反向修正实现对噪声的抑制,构造出...针对传统波达方向(Direction of Arrival,DOA)估计方法在低信噪比、少快拍数条件下表现性能差甚至失效的问题,提出了一种基于重构频域协方差矩阵的波达方位估计方法。该方法根据转化的频域信号进行共轭反向修正实现对噪声的抑制,构造出了新的频域协方差矩阵,利用平均噪声子空间建立空间谱估计函数,通过谱峰搜索估计出信源的方位角。经仿真对比分析,所提改进方法可以识别多个相干信号,并且在低信噪比、少快拍数条件下仍然获得较好的方位估计性能,估计误差较传统算法降低2%~25%。展开更多
传统湿度传感器制造工艺复杂、需有线连接信号,对此,文中提出一种纸基无芯片射频识别(Radio Frequency Identification,RFID)湿度传感器。为提升传感器谐振特性,选择非对称开口环内部分布式加载金属碎片作为传感器结构,聚乙烯醇(PVA)作...传统湿度传感器制造工艺复杂、需有线连接信号,对此,文中提出一种纸基无芯片射频识别(Radio Frequency Identification,RFID)湿度传感器。为提升传感器谐振特性,选择非对称开口环内部分布式加载金属碎片作为传感器结构,聚乙烯醇(PVA)作为湿敏材料,使用遗传算法和HFSS射频仿真软件来设计并优化传感器结构。以喷墨打印技术制作传感器样品,采用滴涂法在传感器表面分别制备了5%、10%、15%三种质量浓度比的PVA薄膜。湿敏特性仿真及测试结果一致表明:PVA与纸基底协同作用可显著提高传感器灵敏度。随PVA浓度增加灵敏度增加,15%PVA传感器灵敏度最高,高湿灵敏度达到12.22 MHz/%RH,但随PVA浓度增加恢复特性变差,5%PVA湿度传感器具有良好的恢复特性,恢复度达83.87%。通过长期多次实验验证了PVA纸基湿度传感器具有良好的温度稳定性与中长期稳定性。与同类研究成果对比,文中设计在感湿范围及灵敏度方面有优势且制造工艺更简单,为低成本湿度传感器的大规模使用提供了可能。展开更多
When clock frequencies exceed gigahertz, the skin depth in analog and digital circuits greatly decreases. The irregular shape of the cross section of the interconnect plays an increasingly important role in interconne...When clock frequencies exceed gigahertz, the skin depth in analog and digital circuits greatly decreases. The irregular shape of the cross section of the interconnect plays an increasingly important role in interconnect parasitic extraction. However, existing methods only focus on the rough surface of the interconnect, while ignoring other irregular shapes, such as the trapezoidal cross section. In this work, a new simulation method is proposed for irregular interconnects, which is applicable to arbitrary irregular shapes and to a wide range of frequencies. The method involves generating a mesh information file firstly, and then extracting the frequency-dependent resistance based on a numerical solution of scalar wave modeling by using the method of moments. The singularity extraction method is used to calculate the self-inductors. The data from experiments verify the accuracy of our proposed method.展开更多
文摘针对传统波达方向(Direction of Arrival,DOA)估计方法在低信噪比、少快拍数条件下表现性能差甚至失效的问题,提出了一种基于重构频域协方差矩阵的波达方位估计方法。该方法根据转化的频域信号进行共轭反向修正实现对噪声的抑制,构造出了新的频域协方差矩阵,利用平均噪声子空间建立空间谱估计函数,通过谱峰搜索估计出信源的方位角。经仿真对比分析,所提改进方法可以识别多个相干信号,并且在低信噪比、少快拍数条件下仍然获得较好的方位估计性能,估计误差较传统算法降低2%~25%。
文摘传统湿度传感器制造工艺复杂、需有线连接信号,对此,文中提出一种纸基无芯片射频识别(Radio Frequency Identification,RFID)湿度传感器。为提升传感器谐振特性,选择非对称开口环内部分布式加载金属碎片作为传感器结构,聚乙烯醇(PVA)作为湿敏材料,使用遗传算法和HFSS射频仿真软件来设计并优化传感器结构。以喷墨打印技术制作传感器样品,采用滴涂法在传感器表面分别制备了5%、10%、15%三种质量浓度比的PVA薄膜。湿敏特性仿真及测试结果一致表明:PVA与纸基底协同作用可显著提高传感器灵敏度。随PVA浓度增加灵敏度增加,15%PVA传感器灵敏度最高,高湿灵敏度达到12.22 MHz/%RH,但随PVA浓度增加恢复特性变差,5%PVA湿度传感器具有良好的恢复特性,恢复度达83.87%。通过长期多次实验验证了PVA纸基湿度传感器具有良好的温度稳定性与中长期稳定性。与同类研究成果对比,文中设计在感湿范围及灵敏度方面有优势且制造工艺更简单,为低成本湿度传感器的大规模使用提供了可能。
文摘When clock frequencies exceed gigahertz, the skin depth in analog and digital circuits greatly decreases. The irregular shape of the cross section of the interconnect plays an increasingly important role in interconnect parasitic extraction. However, existing methods only focus on the rough surface of the interconnect, while ignoring other irregular shapes, such as the trapezoidal cross section. In this work, a new simulation method is proposed for irregular interconnects, which is applicable to arbitrary irregular shapes and to a wide range of frequencies. The method involves generating a mesh information file firstly, and then extracting the frequency-dependent resistance based on a numerical solution of scalar wave modeling by using the method of moments. The singularity extraction method is used to calculate the self-inductors. The data from experiments verify the accuracy of our proposed method.
