A novel high-bandwidth, high-sensitivity differential optical receiver without any additional cost compared to general optical receivers, is proposed for high-speed optical communications and interconnections. High ba...A novel high-bandwidth, high-sensitivity differential optical receiver without any additional cost compared to general optical receivers, is proposed for high-speed optical communications and interconnections. High bandwidth and high sensitivity are achieved through a fully differential transimpedance amplifier with balanced input loads and two photodetectors to convert the incident light into a pair of differential photogenerated currents,respectively. In addition,a corresponding 0.35μm standard CMOS optoelectronic integrated receiver with two 60μm × 30μm, 1. 483pF fingered p^＋/n- well/p-substrate photodiodes is also presented. The simulation results demonstrate that it achieves a 1.37GHz bandwidth and a 81.9dBΩ transimpedance gain,supporting data rates up to at least 2Gbit/s. The device consumes a core area of 0. 198mm^2 and the optical sensitivity is at least - 13dBm for a 10^-12 bit error rate under a 2^15 - 1 PRBS input signal.展开更多
目的探讨压缩感知结合层面编码金属伪影校正(compressed sensing-slice-encoding metal artifact correction,CS-SEMAC)技术用于脊柱金属植入物术后MRI的应用价值。材料与方法比较招募的35例脊柱金属植入物术后患者3.0 T MRI矢状位CS-SE...目的探讨压缩感知结合层面编码金属伪影校正(compressed sensing-slice-encoding metal artifact correction,CS-SEMAC)技术用于脊柱金属植入物术后MRI的应用价值。材料与方法比较招募的35例脊柱金属植入物术后患者3.0 T MRI矢状位CS-SEMAC序列、高带宽(high bandwidth,HBW)序列和水脂分离(Dixon)三种序列在金属植入物伪影面积、椎体信噪比(signal-to-noise ratio,SNR)、图像质量、图像清晰度、脂肪抑制效果以及植入物周围解剖结构的可见性方面的差异。结果CS-SEMAC在T1、T2矢状位图像上金属伪影面积分别为(15.45±6.84)、(22.23±9.76)cm^(2),显著低于其他两种序列,差异具有统计学意义(P<0.001);三种序列在T2抑脂矢状面图像上的SNR两两比较显示:HBW序列椎体SNR显著高于其他两种序列,Dixon序列椎体SNR显著低于其他两种序列,CS-SEMAC序列椎体SNR低于HBW序列,高于Dixon序列,差异均有统计学意义(P<0.001);在图像清晰度上,T2WI-tirm-CS-SEMAC序列评分低于其他两种序列,差异具有统计学意义(P<0.001);T2WI-tirm-CS-SEMAC序列在图像质量和脂肪抑制效果方面评分显著优于其他两种序列,差异具有统计学意义(P<0.001);并且CS-SEMAC序列相较于其他两种序列更能清晰显示植入物周围椎体、椎弓根、椎间孔及神经根,差异具有统计学意义(P<0.001)。结论CS-SEMAC序列相比于HBW、Dixon序列能够有效减少植入物周围的金属伪影,并且能显著提高T2抑脂序列的图像质量和脂肪抑制效果,虽然在T2抑脂上金属植入物邻近椎体SNR相比HBW序列有所下降,图像比HBW和Dixon图像略模糊,但是椎体周围关键解剖结构的可见度明显提升,对脊柱术后解剖结构的显示有一定优势。展开更多
Typically,the achievable positioning bandwidth for piezo-actuated nanopositioners is severely limited by the first,lightly-damped resonance.To overcome this issue,a variety of open-and closed-loop control techniques t...Typically,the achievable positioning bandwidth for piezo-actuated nanopositioners is severely limited by the first,lightly-damped resonance.To overcome this issue,a variety of open-and closed-loop control techniques that commonly combine damping and tracking actions,have been reported in literature.However,in almost all these cases,the achievable closed-loop bandwidth is still limited by the original open-loop resonant frequency of the respective positioning axis.Shifting this resonance to a higher frequency would undoubtedly result in a wider bandwidth.However,such a shift typically entails a major mechanical redesign of the nanopositioner.The integral resonant control(IRC)has been reported earlier to demonstrate the significant performance enhancement,robustness to parameter uncertainty,gua-ranteed stability and design flexibility it affords.To further exploit the IRC scheme’s capabilities,this paper presents a method of actively shifting the resonant frequency of a nanopositioner’s axis,thereby delivering a wider closed-loop positioning bandwidth when controlled with the IRC scheme.The IRC damping control is augmented with a standard integral tracking controller to improve positioning accuracy.And both damping and tracking control parameters are analytically optimized to result in a Butterworth Filter mimicking pole-placement—maximally flat passband response.Experiments are conducted on a nanopositioner’s axis with an open-loop resonance at 508 Hz.It is shown that by employing the active resonance shifting,the closed-loop positioning bandwidth is increased from 73 to 576 Hz.Consequently,the root-mean-square tracking errors for a 100 Hz triangular trajectory are reduced by 93%.展开更多
随着高带宽需求的不断增长,软件定义网络(Software Defined Networking,SDN)领域内的切片分组网(Slicing Packet Network,SPN)网络架构应运而生。这一架构通过独到的设计,为高速数据传输应用提供了所需的弹性与伸缩能力。然而,针对高带...随着高带宽需求的不断增长,软件定义网络(Software Defined Networking,SDN)领域内的切片分组网(Slicing Packet Network,SPN)网络架构应运而生。这一架构通过独到的设计,为高速数据传输应用提供了所需的弹性与伸缩能力。然而,针对高带宽应用的SPN网络却面临着带宽攻击、数据隐私泄露以及认证与授权管理等问题。文章深入分析这些问题,并提出针对性的解决策略与技术手段。这些解决方案涵盖流量监管、加密防护、隐私保密、身份验证及权力控制等关键领域,并提供一整套安全准则与流量管控技术。展开更多
文摘A novel high-bandwidth, high-sensitivity differential optical receiver without any additional cost compared to general optical receivers, is proposed for high-speed optical communications and interconnections. High bandwidth and high sensitivity are achieved through a fully differential transimpedance amplifier with balanced input loads and two photodetectors to convert the incident light into a pair of differential photogenerated currents,respectively. In addition,a corresponding 0.35μm standard CMOS optoelectronic integrated receiver with two 60μm × 30μm, 1. 483pF fingered p^＋/n- well/p-substrate photodiodes is also presented. The simulation results demonstrate that it achieves a 1.37GHz bandwidth and a 81.9dBΩ transimpedance gain,supporting data rates up to at least 2Gbit/s. The device consumes a core area of 0. 198mm^2 and the optical sensitivity is at least - 13dBm for a 10^-12 bit error rate under a 2^15 - 1 PRBS input signal.
文摘目的探讨压缩感知结合层面编码金属伪影校正(compressed sensing-slice-encoding metal artifact correction,CS-SEMAC)技术用于脊柱金属植入物术后MRI的应用价值。材料与方法比较招募的35例脊柱金属植入物术后患者3.0 T MRI矢状位CS-SEMAC序列、高带宽(high bandwidth,HBW)序列和水脂分离(Dixon)三种序列在金属植入物伪影面积、椎体信噪比(signal-to-noise ratio,SNR)、图像质量、图像清晰度、脂肪抑制效果以及植入物周围解剖结构的可见性方面的差异。结果CS-SEMAC在T1、T2矢状位图像上金属伪影面积分别为(15.45±6.84)、(22.23±9.76)cm^(2),显著低于其他两种序列,差异具有统计学意义(P<0.001);三种序列在T2抑脂矢状面图像上的SNR两两比较显示:HBW序列椎体SNR显著高于其他两种序列,Dixon序列椎体SNR显著低于其他两种序列,CS-SEMAC序列椎体SNR低于HBW序列,高于Dixon序列,差异均有统计学意义(P<0.001);在图像清晰度上,T2WI-tirm-CS-SEMAC序列评分低于其他两种序列,差异具有统计学意义(P<0.001);T2WI-tirm-CS-SEMAC序列在图像质量和脂肪抑制效果方面评分显著优于其他两种序列,差异具有统计学意义(P<0.001);并且CS-SEMAC序列相较于其他两种序列更能清晰显示植入物周围椎体、椎弓根、椎间孔及神经根,差异具有统计学意义(P<0.001)。结论CS-SEMAC序列相比于HBW、Dixon序列能够有效减少植入物周围的金属伪影,并且能显著提高T2抑脂序列的图像质量和脂肪抑制效果,虽然在T2抑脂上金属植入物邻近椎体SNR相比HBW序列有所下降,图像比HBW和Dixon图像略模糊,但是椎体周围关键解剖结构的可见度明显提升,对脊柱术后解剖结构的显示有一定优势。
基金This work was supported in part by the National Natural Science Foundation of China(Grant Nos.U2013211 and 51975375)the Open Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems,China(Grant No.GZKF-202003)the Binks Trust Visiting Research Fellowship(2018),University of Aberdeen,UK,awarded to Dr.Sumeet S.Aphale.
文摘Typically,the achievable positioning bandwidth for piezo-actuated nanopositioners is severely limited by the first,lightly-damped resonance.To overcome this issue,a variety of open-and closed-loop control techniques that commonly combine damping and tracking actions,have been reported in literature.However,in almost all these cases,the achievable closed-loop bandwidth is still limited by the original open-loop resonant frequency of the respective positioning axis.Shifting this resonance to a higher frequency would undoubtedly result in a wider bandwidth.However,such a shift typically entails a major mechanical redesign of the nanopositioner.The integral resonant control(IRC)has been reported earlier to demonstrate the significant performance enhancement,robustness to parameter uncertainty,gua-ranteed stability and design flexibility it affords.To further exploit the IRC scheme’s capabilities,this paper presents a method of actively shifting the resonant frequency of a nanopositioner’s axis,thereby delivering a wider closed-loop positioning bandwidth when controlled with the IRC scheme.The IRC damping control is augmented with a standard integral tracking controller to improve positioning accuracy.And both damping and tracking control parameters are analytically optimized to result in a Butterworth Filter mimicking pole-placement—maximally flat passband response.Experiments are conducted on a nanopositioner’s axis with an open-loop resonance at 508 Hz.It is shown that by employing the active resonance shifting,the closed-loop positioning bandwidth is increased from 73 to 576 Hz.Consequently,the root-mean-square tracking errors for a 100 Hz triangular trajectory are reduced by 93%.
文摘随着高带宽需求的不断增长,软件定义网络(Software Defined Networking,SDN)领域内的切片分组网(Slicing Packet Network,SPN)网络架构应运而生。这一架构通过独到的设计,为高速数据传输应用提供了所需的弹性与伸缩能力。然而,针对高带宽应用的SPN网络却面临着带宽攻击、数据隐私泄露以及认证与授权管理等问题。文章深入分析这些问题,并提出针对性的解决策略与技术手段。这些解决方案涵盖流量监管、加密防护、隐私保密、身份验证及权力控制等关键领域,并提供一整套安全准则与流量管控技术。
