The resonant frequency of metamaterials structured with split ring resonator(SRR) meta-atoms is determined primarily through the capacitance and inductance of the individual meta-atoms. Two designs that vary inductanc...The resonant frequency of metamaterials structured with split ring resonator(SRR) meta-atoms is determined primarily through the capacitance and inductance of the individual meta-atoms. Two designs that vary inductance incrementally were modeled, simulated, fabricated, and tested to investigate the role inductance plays in metamaterial designs. The designs consisted of strategically adding sections to the SRR to increase the inductance, but in a manner that minimized capacitance variations. Each design showed a shift in resonant frequency that was proportional to the length of the added section. As the length of each section was increased, the resonant frequency shifted from 2.78 GHz to 2.18 GHz.展开更多
It has long been a challenging task to improve the light collection efficiency of conventional image sensors built with color filters that inevitably cause the energy loss of out-of-band photons. Here, we demonstrate ...It has long been a challenging task to improve the light collection efficiency of conventional image sensors built with color filters that inevitably cause the energy loss of out-of-band photons. Here, we demonstrate a pixelated spectral router based on a sparse meta-atom array, which can efficiently separate incident R(600±700 nm), G(500±600 nm), and B(400±500 nm)band light to the corresponding pixels of a Bayer image sensor, providing over 56% signal enhancement above the traditional color filter scheme. It is enabled by simple compound Si_(3)N_(4) nanostructures, which are very suitable for massive production. Imaging experiments are conducted to verify the router's potential for real applications. The complementary metal-oxide-semiconductor(CMOS)-compatible spectral router scheme is also found to be robust and can be freely adapted to image sensors of various pixel sizes, having great potential in building the new generation of high-performance image sensing components.展开更多
Metasurfaces consisting of subwavelength structures,so-called meta-atoms,have steadily attracted considerable attention for advanced holography due to their advantages in terms of high-resolution holographic images,la...Metasurfaces consisting of subwavelength structures,so-called meta-atoms,have steadily attracted considerable attention for advanced holography due to their advantages in terms of high-resolution holographic images,large field of view,and compact device volume.In contrast to conventional holographic displays using bulky conventional diffractive optical elements,metasurface holography enables arbitrary complex wavefront shaping with a much smaller footprint.In this review,we classify metasurface holography according to the meta-atom design methodologies,which can further expand hologram functionalities.We describe light-matter interactions,particularly in metasurface systems,using the relevant the Jones matrix to rigorously explain modulations of the amplitude,phase,and polarization of light.Six different types of metaatoms are presented,and the corresponding achievable wavefronts that form the holographic images in the far-field are also provided.Such a simple classification will give a straightforward approach to design and further realize advanced metasurface holographic devices.展开更多
针对原子优化算法寻优精度弱且易陷入局部极值的问题,本文从种群多样性、参数适应性和位置动态性角度提出一种融合混沌优化、振幅随机补偿和步长演变机制改进的原子搜索优化算法(improved atom search optimization,IASO),并将其成功应...针对原子优化算法寻优精度弱且易陷入局部极值的问题,本文从种群多样性、参数适应性和位置动态性角度提出一种融合混沌优化、振幅随机补偿和步长演变机制改进的原子搜索优化算法(improved atom search optimization,IASO),并将其成功应用于分类任务。首先,引入帐篷映射(Tent混沌)增强原子种群在搜索空间中的分布均匀性;其次,通过构建振幅函数对算法参数进行随机扰动并加入步长演变因子更新原子位置,以增强算法全局性和收敛性;最后,再将改进算法应用于误差反馈神经网络(BP神经网络)参数优化。通过与6种元启发式算法在20个基准测试函数下的数值实验对比表明:IASO不仅在求解多维基准函数上具有好的寻优性能,且在对BP神经网络参数进行优化时相较于2种对比算法具有更高的分类精度。展开更多
We propose the design of anisotropic metamaterials with cascading meta-atoms.Each meta-atom array behaves as an impedance-tuned interface and dramatically modifies the complex reflection and transmission coefficients....We propose the design of anisotropic metamaterials with cascading meta-atoms.Each meta-atom array behaves as an impedance-tuned interface and dramatically modifies the complex reflection and transmission coefficients.By engineering the frequency-dependent impedances,the reflection phase difference along the two axes of anisotropic metamaterials approximates to a constant in a wide range.We numerically demonstrate the proposed anisotropic metamaterials can accomplish achromatic polarization transformation from 0.5 THz to 3.1 THz.The polarization conversion ratio is higher than 80%,which exhibits excellent agreements with the theoretical calculation.Such design is scalable to other bands and can provide helpful guidance in broadband devices design.展开更多
目的 系统评价雾化吸入乙酰半胱氨酸溶液辅助治疗支气管肺炎的疗效,为临床提供循证参考。方法 计算机检索Cochrane Library,Pubmed,EMbase,CNKI,维普和万方数据库,检索时限均从建库到2017年11月,收集雾化吸入乙酰半胱氨酸溶液辅助治疗...目的 系统评价雾化吸入乙酰半胱氨酸溶液辅助治疗支气管肺炎的疗效,为临床提供循证参考。方法 计算机检索Cochrane Library,Pubmed,EMbase,CNKI,维普和万方数据库,检索时限均从建库到2017年11月,收集雾化吸入乙酰半胱氨酸溶液辅助治疗支气管肺炎的相关研究,对符合纳入标准的研究进行提取资料和质量评价,采用Rev Man 5.3统计软件进行Meta分析。结果 共纳入7项研究,合计448例患者。Meta分析结果显示:雾化吸入乙酰半胱氨酸溶液对支气管肺炎的治疗效果优于对照组,差异有统计学意义〔有效性:OR=4.60,95%CI(2.59,8.16), P <0.00001;显效性:OR=2.53,95%CI(1.80,3.57),P <0.00001〕;在改善临床症状体征和住院时间方面也优于对照组,差异有统计学意义〔体温恢复正常所需的时间:MD=-0.53,95%CI(-0.63,-0.44), P <0.00001;咳嗽消失所需的时间:MD=-1.45,95%CI(-1.87,-1.03), P <0.00001;气促消失所需的时间:MD=-1.13,95%CI(-1.58,-0.68), P <0.00001;肺部啰音消失所需的时间:MD=-1.07,95%CI(-1.62,-0.52), P =0.0002;住院时间:MD=-2.22,95%CI(-3.58,-0.86),P =0.001〕。结论 雾化吸入乙酰半胱氨酸可有效提高支气管肺炎患儿的治疗效果,缩短临床症状、体征消失的时间和住院时间,且安全性较好。但是由于纳入研究的数量和质量限制,以上结论尚待开展更多高质量研究加以验证。展开更多
[目的]系统评价中药雾化吸入辅助治疗呼吸机相关性肺炎的临床疗效及预后情况。[方法]从建库到2021年4月,检索PubMed、Cochrane Library、Web of Science、Clinical Trials、中国知网、维普、万方、中国生物医学文献数据库,纳入中药雾化...[目的]系统评价中药雾化吸入辅助治疗呼吸机相关性肺炎的临床疗效及预后情况。[方法]从建库到2021年4月,检索PubMed、Cochrane Library、Web of Science、Clinical Trials、中国知网、维普、万方、中国生物医学文献数据库,纳入中药雾化吸入辅助治疗呼吸机相关性肺炎的随机对照试验,以临床总有效率、白细胞水平、降钙素原(procalcitonin,PCT)水平、重症监护室(intensive care unit,ICU)住院时间、氧合指数为结局指标,提取并合并数据。使用Cochrane协作网偏倚风险评估工具进行单个研究的质量评价,使用Rev Man 5.4软件进行Meta分析。[结果]最终纳入12篇文献,共计909例。Meta分析结果显示:中药雾化吸入组临床总有效率明显优于对照组[比值比(odds ratio,OR)=4.27,95%可信区间(confidence interval,CI)(2.53,7.20),P<0.00001];中药雾化吸入可以降低白细胞水平[加权均数差(mean difference,MD)=-1.11,95%CI(-1.40,-0.81),P<0.00001];降低PCT水平[MD=-0.49,95%CI(-0.59,-0.40),P<0.00001];缩短ICU住院天数[MD=-2.70,95%CI(-3.13,-2.27),P<0.00001];提高氧合指数[MD=52.07,95%CI(47.44,56.71),P<0.00001]。[结论]中药雾化吸入辅助治疗呼吸机相关性肺炎可提高临床疗效并改善预后,但存在发表偏倚,需进一步验证。展开更多
文摘The resonant frequency of metamaterials structured with split ring resonator(SRR) meta-atoms is determined primarily through the capacitance and inductance of the individual meta-atoms. Two designs that vary inductance incrementally were modeled, simulated, fabricated, and tested to investigate the role inductance plays in metamaterial designs. The designs consisted of strategically adding sections to the SRR to increase the inductance, but in a manner that minimized capacitance variations. Each design showed a shift in resonant frequency that was proportional to the length of the added section. As the length of each section was increased, the resonant frequency shifted from 2.78 GHz to 2.18 GHz.
基金supported by the Natural Science Foundation of China (Nos. 62075196 and 62105282)the Natural Science Foundation of Zhejiang Province (No. LDT23F05014F05)+1 种基金the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang (No. 2021R01001)the Fundamental Research Funds for the Central Universities。
文摘It has long been a challenging task to improve the light collection efficiency of conventional image sensors built with color filters that inevitably cause the energy loss of out-of-band photons. Here, we demonstrate a pixelated spectral router based on a sparse meta-atom array, which can efficiently separate incident R(600±700 nm), G(500±600 nm), and B(400±500 nm)band light to the corresponding pixels of a Bayer image sensor, providing over 56% signal enhancement above the traditional color filter scheme. It is enabled by simple compound Si_(3)N_(4) nanostructures, which are very suitable for massive production. Imaging experiments are conducted to verify the router's potential for real applications. The complementary metal-oxide-semiconductor(CMOS)-compatible spectral router scheme is also found to be robust and can be freely adapted to image sensors of various pixel sizes, having great potential in building the new generation of high-performance image sensing components.
基金Hyundai Motor Group,Grant/Award Number:Hyundai Motor Chung Mong-Koo fellowshipLG Display,Grant/Award Number:LGD-SNU incubation programNational Research Foundation of Korea,Grant/Award Numbers:CAMM-2019M3A6B3030637,NRF-2019R1A2C3003129,NRF-2019R1A5A8080290,NRF-2021R1C1C2004291。
文摘Metasurfaces consisting of subwavelength structures,so-called meta-atoms,have steadily attracted considerable attention for advanced holography due to their advantages in terms of high-resolution holographic images,large field of view,and compact device volume.In contrast to conventional holographic displays using bulky conventional diffractive optical elements,metasurface holography enables arbitrary complex wavefront shaping with a much smaller footprint.In this review,we classify metasurface holography according to the meta-atom design methodologies,which can further expand hologram functionalities.We describe light-matter interactions,particularly in metasurface systems,using the relevant the Jones matrix to rigorously explain modulations of the amplitude,phase,and polarization of light.Six different types of metaatoms are presented,and the corresponding achievable wavefronts that form the holographic images in the far-field are also provided.Such a simple classification will give a straightforward approach to design and further realize advanced metasurface holographic devices.
文摘针对原子优化算法寻优精度弱且易陷入局部极值的问题,本文从种群多样性、参数适应性和位置动态性角度提出一种融合混沌优化、振幅随机补偿和步长演变机制改进的原子搜索优化算法(improved atom search optimization,IASO),并将其成功应用于分类任务。首先,引入帐篷映射(Tent混沌)增强原子种群在搜索空间中的分布均匀性;其次,通过构建振幅函数对算法参数进行随机扰动并加入步长演变因子更新原子位置,以增强算法全局性和收敛性;最后,再将改进算法应用于误差反馈神经网络(BP神经网络)参数优化。通过与6种元启发式算法在20个基准测试函数下的数值实验对比表明:IASO不仅在求解多维基准函数上具有好的寻优性能,且在对BP神经网络参数进行优化时相较于2种对比算法具有更高的分类精度。
基金supported in part by National Science Foundation(NSF)
文摘We propose the design of anisotropic metamaterials with cascading meta-atoms.Each meta-atom array behaves as an impedance-tuned interface and dramatically modifies the complex reflection and transmission coefficients.By engineering the frequency-dependent impedances,the reflection phase difference along the two axes of anisotropic metamaterials approximates to a constant in a wide range.We numerically demonstrate the proposed anisotropic metamaterials can accomplish achromatic polarization transformation from 0.5 THz to 3.1 THz.The polarization conversion ratio is higher than 80%,which exhibits excellent agreements with the theoretical calculation.Such design is scalable to other bands and can provide helpful guidance in broadband devices design.
文摘目的 系统评价雾化吸入乙酰半胱氨酸溶液辅助治疗支气管肺炎的疗效,为临床提供循证参考。方法 计算机检索Cochrane Library,Pubmed,EMbase,CNKI,维普和万方数据库,检索时限均从建库到2017年11月,收集雾化吸入乙酰半胱氨酸溶液辅助治疗支气管肺炎的相关研究,对符合纳入标准的研究进行提取资料和质量评价,采用Rev Man 5.3统计软件进行Meta分析。结果 共纳入7项研究,合计448例患者。Meta分析结果显示:雾化吸入乙酰半胱氨酸溶液对支气管肺炎的治疗效果优于对照组,差异有统计学意义〔有效性:OR=4.60,95%CI(2.59,8.16), P <0.00001;显效性:OR=2.53,95%CI(1.80,3.57),P <0.00001〕;在改善临床症状体征和住院时间方面也优于对照组,差异有统计学意义〔体温恢复正常所需的时间:MD=-0.53,95%CI(-0.63,-0.44), P <0.00001;咳嗽消失所需的时间:MD=-1.45,95%CI(-1.87,-1.03), P <0.00001;气促消失所需的时间:MD=-1.13,95%CI(-1.58,-0.68), P <0.00001;肺部啰音消失所需的时间:MD=-1.07,95%CI(-1.62,-0.52), P =0.0002;住院时间:MD=-2.22,95%CI(-3.58,-0.86),P =0.001〕。结论 雾化吸入乙酰半胱氨酸可有效提高支气管肺炎患儿的治疗效果,缩短临床症状、体征消失的时间和住院时间,且安全性较好。但是由于纳入研究的数量和质量限制,以上结论尚待开展更多高质量研究加以验证。
文摘[目的]系统评价中药雾化吸入辅助治疗呼吸机相关性肺炎的临床疗效及预后情况。[方法]从建库到2021年4月,检索PubMed、Cochrane Library、Web of Science、Clinical Trials、中国知网、维普、万方、中国生物医学文献数据库,纳入中药雾化吸入辅助治疗呼吸机相关性肺炎的随机对照试验,以临床总有效率、白细胞水平、降钙素原(procalcitonin,PCT)水平、重症监护室(intensive care unit,ICU)住院时间、氧合指数为结局指标,提取并合并数据。使用Cochrane协作网偏倚风险评估工具进行单个研究的质量评价,使用Rev Man 5.4软件进行Meta分析。[结果]最终纳入12篇文献,共计909例。Meta分析结果显示:中药雾化吸入组临床总有效率明显优于对照组[比值比(odds ratio,OR)=4.27,95%可信区间(confidence interval,CI)(2.53,7.20),P<0.00001];中药雾化吸入可以降低白细胞水平[加权均数差(mean difference,MD)=-1.11,95%CI(-1.40,-0.81),P<0.00001];降低PCT水平[MD=-0.49,95%CI(-0.59,-0.40),P<0.00001];缩短ICU住院天数[MD=-2.70,95%CI(-3.13,-2.27),P<0.00001];提高氧合指数[MD=52.07,95%CI(47.44,56.71),P<0.00001]。[结论]中药雾化吸入辅助治疗呼吸机相关性肺炎可提高临床疗效并改善预后,但存在发表偏倚,需进一步验证。
