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基于Cascade结构的牛脸姿态估计 预览
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作者 苟先太 黄巍 刘琪芬 《计算机系统应用》 2019年第7期240-245,共6页
随着牲畜牛逐年增加,单角度特征编码这种身份认证方法在数据容量上已无法满足目前的需求.本文给出一种cascade结构,使用SSD模型对牛脸进行检测,之后使用MobileNet对牛脸姿态角度进行估计.为多角度特征编码打下坚实的特征基础.实验表明,c... 随着牲畜牛逐年增加,单角度特征编码这种身份认证方法在数据容量上已无法满足目前的需求.本文给出一种cascade结构,使用SSD模型对牛脸进行检测,之后使用MobileNet对牛脸姿态角度进行估计.为多角度特征编码打下坚实的特征基础.实验表明,cascade结构在牛脸检测、姿态角度估计任务中均能得到一个较高的准确度. 展开更多
关键词 CASCADE 牛脸检测 姿态角度
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梯级水电建设环境下土石围堰漫溢风险研究 预览
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作者 陈玉玺 卢晓春 +2 位作者 陈渴鑫 郭志杰 陈博夫 《水利水电技术》 北大核心 2019年第2期177-183,共7页
针对在梯级水电建设环境下围堰度汛受来水、泄流等不确定性因素的耦合影响,以评估工程漫溢风险为目标,采用Monte-Carlo法仿真抽样技术及现有风险分析理论,按工程流域面积占比推求各级围堰施工期不确定性来水,结合工程安全度汛、溃堰失... 针对在梯级水电建设环境下围堰度汛受来水、泄流等不确定性因素的耦合影响,以评估工程漫溢风险为目标,采用Monte-Carlo法仿真抽样技术及现有风险分析理论,按工程流域面积占比推求各级围堰施工期不确定性来水,结合工程安全度汛、溃堰失效两种不同泄洪方式建立梯级开发条件下土石围堰漫溢风险计算模型,并使用该模型进行了实例分析。结果表明:在梯级水电建设环境下上游工程安全度汛能有效降低下游工程的漫溢风险,与泄洪有关的水力参数对工程漫溢风险影响不大,而水文风险则是影响工程安全度汛的主要因素;当上游工程漫溢溃堰,改变了下游工程前的洪水组合方式会显著增大其漫溢失效的概率。研究成果可以合理预测梯级水电建设环境下工程的漫溢风险,能为梯级建设环境下土石围堰的设计及施工度汛提供重要的决策支持。 展开更多
关键词 梯级 土石围堰 施工安全度汛 漫溢风险 MONTE - Carlo法 预测模型 流域梯级水电开发
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多电平逆变电路主要技术分支专利分析 预览
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作者 王宇 赵杰 《河南科技》 2019年第9期50-52,共3页
多电平逆变电路已经成为电力领域中不可或缺的一种逆变电路,其广泛应用于直流输电、新能源发电、储能以及UPS电源等多个相关场合。除了可以获得较低的谐波畸变率,减少开关器件的开关损耗,多电平逆变电路利用较少的开关数量,产生多个电... 多电平逆变电路已经成为电力领域中不可或缺的一种逆变电路,其广泛应用于直流输电、新能源发电、储能以及UPS电源等多个相关场合。除了可以获得较低的谐波畸变率,减少开关器件的开关损耗,多电平逆变电路利用较少的开关数量,产生多个电压等级的高压电压以满足不同电压等级的负载需求。根据多电平逆变电路的拓扑结构,可以将其主要分为中点箝位型和级联H桥型这两种主要类型. 展开更多
关键词 多电平 中点箝位 级联 H桥
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Self-assembled nanozyme complexes with enhanced cascade activity and high stability for colorimetric detection of glucose
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作者 Meng Liu Zhihao Li +2 位作者 Yingxue Li jiajia Chen Quan Yuan 《中国化学快报:英文版》 SCIE CAS CSCD 2019年第5期1009-1012,共4页
Construction of multi-enzyme complexes not only can help expand the understanding of biological mechanisms, but also holds great promise in biosynthesis, biosensing and biomedicine. Herein, a hybrid multi-enzyme syste... Construction of multi-enzyme complexes not only can help expand the understanding of biological mechanisms, but also holds great promise in biosynthesis, biosensing and biomedicine. Herein, a hybrid multi-enzyme system, CeO2/glucose oxidase(GOx) nanocomplex was developed via self-assembly and exhibited excellent catalytic activity toward cascade reactions. Compared to mixed GOx and CeO2, the nanocomplexes displayed enhanced efficiency, mainly attributed to the minimal diffusion of intermediate in the nanocomplexes system. Moreover, the nanocomplexes exhibited outstanding long-term stability and excellent recyclability. Benefiting from these merits, a highly sensitive and selective biosensor for colorimetric detection of glucose was constructed based on CeO2/GOx nanocomplexes. Such a self-assembled nanozyme complex offers a simple and efficient example to build spatially confined multi-enzyme systems to potentiate their applications in energy conversion,detoxification and bioanalysis. 展开更多
关键词 Nanozyme CEO2 CASCADE CATALYZE Stability
电力电子变压器的高速铁路同相供电系统及控制方法 预览
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作者 夏焰坤 《电力系统及其自动化学报》 CSCD 北大核心 2019年第5期98-102,共5页
传统的同相牵引供电系统能够解决电气化铁路供电长期存在的电能质量和过电分相等问题,但存在高压大功率降压隔离工频变压器。电力电子变压器的同相供电系统能取消工频变压器,具有重量轻、成本低等优点。首先提出了该系统的结构和工作原... 传统的同相牵引供电系统能够解决电气化铁路供电长期存在的电能质量和过电分相等问题,但存在高压大功率降压隔离工频变压器。电力电子变压器的同相供电系统能取消工频变压器,具有重量轻、成本低等优点。首先提出了该系统的结构和工作原理;其次采用相量法和相量图分析了系统负序补偿平衡原理,根据系统结构特点提出了高压级联侧电压平衡控制方法和直直隔离侧控制方法;最后在MATLAB/Simulink仿真平台上建立了仿真模型,仿真结果验证了所提结构和控制方法的有效性。 展开更多
关键词 电力电子变压器 补偿 高速铁路 同相供电系统 级联
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Highly efficient electro-optically Q-switched 473 nm blue laser
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作者 陆婷婷 马剑 +1 位作者 朱小磊 陈卫标 《中国光学快报:英文版》 SCIE EI CAS CSCD 2019年第5期49-52,共4页
An external frequency doubling electro-optically Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) 473 nm blue laser was demonstrated. With absorbed pump energy of 48 mJ at 100 Hz repetition rate, about 2 mJ... An external frequency doubling electro-optically Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) 473 nm blue laser was demonstrated. With absorbed pump energy of 48 mJ at 100 Hz repetition rate, about 2 mJ of 473 nm blue laser pulse energy was achieved by cascade frequency doubling. The second harmonic conversion efficiency was 64.5%, and overall optical-optical efficiency was 4.2%, respectively. The blue laser pulse width was less than 10 ns, and beam quality factor was less than 2.4. 展开更多
关键词 Highly efficient electro-optically Q-SWITCHED BLUE laser CASCADE frequency doubling
A combined application of micro-vortex generator and boundary layer suction in a high-load compressor cascade
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作者 Shan MA Wuli CHU +2 位作者 Haoguang ZHANG Xiangjun LI Haiyang KUANG 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第5期1171-1183,共13页
In the current study, the effects of a combined application between micro-vortex generator and boundary layer suction on the flow characteristics of a high-load compressor cascade are investigated. The micro-vortex ge... In the current study, the effects of a combined application between micro-vortex generator and boundary layer suction on the flow characteristics of a high-load compressor cascade are investigated. The micro-vortex generator with a special configuration and the longitudinal suction slot are adopted. The calculated results show that a reverse flow region, which is considered the main reason for occurring stall at 7.9° incidence, grows and collapses rapidly near the leading edge and leads to two critical points occurring on the end-wall with the increasing incidence in the baseline. As the micro-vortex generator is introduced in the baseline cascade, the corner separation is switched to a trailing edge separation by the thrust from the induced vortex. Meanwhile, the occurrence of failure is delayed due to the mixed low energy fluid and main flow. The synergistic effects between the micro-vortex generator and the boundary layer suction on the performance of the cascade are superior to the baseline at all the incidence conditions before the occurrence of failure, and the sudden deterioration of the cascade occurs at 10.3° incidence. The optimal results show that the farther upstream suction position, the lower total pressure loss of the cascade with vortex generator at the near stall condition. Moreover, the induced vortex with a leg can migrate the accumulated low energy fluid backward to delay the occurrence of stall. 展开更多
关键词 Boundary layer SUCTION Flow control strategies High-load COMPRESSOR CASCADE Numerical simulations VORTEX generators
过热器喷水减温串级回路参数优化计算及实现方法 预览
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作者 白雄怀 王文兰 《能源与节能》 2019年第5期153-155,163共4页
精确计算减温器喷水的主汽温度串级回路的调节器参数,可以使系统获得更快的响应,同时稳定过热蒸汽出口的温度参数。通过优化计算,说明闭环响应速度、工作周期变化的一种趋势,从而找到可能的变化方向,便于精确认识和优化常规的控制策略。
关键词 喷水减温 串级 参数优化 周期 实现方法
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基于共源共栅结构的高输出功率VCO 预览
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作者 周雅 焦晓波 《雷达科学与技术》 北大核心 2019年第2期232-236,共5页
为了降低与射频系统级相关的功耗,以及增加输出功率,提出了一种共源共栅结构的CMOS VCO。所提出的VCO核心包含有共源共栅结构,以增加VCO的供电电压。为了降低与栅源级间和栅漏级间击穿相关的可靠性问题,将共源晶体管的栅级节点与共栅晶... 为了降低与射频系统级相关的功耗,以及增加输出功率,提出了一种共源共栅结构的CMOS VCO。所提出的VCO核心包含有共源共栅结构,以增加VCO的供电电压。为了降低与栅源级间和栅漏级间击穿相关的可靠性问题,将共源晶体管的栅级节点与共栅晶体管的源级节点相连。为了验证所提出VCO的有效性,采用90 nm的RF CMOS工艺设计了一款2.4 GHz的CMOS VCO芯片,由测试结果可得,该款VCO在2 V电源电压供电下取得了相对较高的输出功率、较低的相位噪声以及变化较平缓的振荡频率。 展开更多
关键词 共源共栅 交叉耦合 压控振荡器 互补金属氧化物半导体 高输出功率
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Mn(Ⅲ)-mediated radical cascade reaction of boronic acids with isocyanides:Synthesis of diimide derivatives
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作者 Fei Wang Tian-Qi Wei +2 位作者 Pei Xu Shun-Yi Wang Shun-Jun Ji 《中国化学快报:英文版》 SCIE CAS CSCD 2019年第2期379-382,共4页
A manganese (Ⅲ)-promoted oxidative radical cascade reaction of easily accessible arylboronic acids with isocyanides to construct diimide derivatives was studied. This protocol provides a new way to synthesis of acety... A manganese (Ⅲ)-promoted oxidative radical cascade reaction of easily accessible arylboronic acids with isocyanides to construct diimide derivatives was studied. This protocol provides a new way to synthesis of acetyl diimide derivatives. New C-C, C-N and C=O bonds were formed in one step. 展开更多
关键词 Mn(OAc)3 ISOCYANIDE Arylboronic acid DIIMIDE DERIVATIVES RADICAL CASCADE
Synthesis of 9-phenol-substituted xanthenes by cascade O-insertion/1,6-conjugate addition of benzyne with ortho-hydroxyphenyl substituted para-quinone methides
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作者 Zhijuan Li Weihua Wang +3 位作者 Hui Jian Wenjuan Li Bin Dai Lin He 《中国化学快报:英文版》 SCIE CAS CSCD 2019年第2期386-388,共3页
The cascade O-insertion/1,6 conjugate addition between benzynes and ortho-hydroxyphenyl substituted para-quinone methides has been reported, affording 9-phenol substituted xanthenes in 49%-84% yields.
关键词 Benzyne para-Quinone methides XANTHENE CASCADE reaction Cycloaddition
复叠式制冷循环软件设计及应用
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作者 陈清华 吴宇 +2 位作者 苏国用 宋皓然 王皖南 《低温与超导》 CAS 北大核心 2019年第1期82-87,共6页
设计了一款由Matlab中GUI界面开发研制的制冷软件,包括参数输入,制冷环境、界面互换,焓值检测以及结果显示五个窗口界面。该制冷软件,基于蒸发式压缩制冷循环原理,对复叠式制冷系统进行分析,根据蒸发温度,冷凝温度,制冷量确定压缩机功率... 设计了一款由Matlab中GUI界面开发研制的制冷软件,包括参数输入,制冷环境、界面互换,焓值检测以及结果显示五个窗口界面。该制冷软件,基于蒸发式压缩制冷循环原理,对复叠式制冷系统进行分析,根据蒸发温度,冷凝温度,制冷量确定压缩机功率,得出系统COP。同时,根据环境计算所需制冷量,并应用于恒温恒湿试验箱。通过实际制冷循环对比,发现计算结果与实际值的误差小于5%,从而证明软件的准确性。 展开更多
关键词 MATLAB 制冷软件 复叠 制冷量 功率
离心法生产^131Xe同位素技术研究 预览
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作者 耿冰霜 谢全新 《同位素》 CAS 2019年第1期62-68,I0004共8页
为利用离心分离方法将^131Xe同位素丰度浓缩到90%以上,本研究采用多组分矩形级联算法进行级联计算,分析中间组分的分离特性,研究级联长度、供料位置、级联分流比等参数对分离效果的影响。对分离^131Xe同位素的矩形级联分离方案进行优化... 为利用离心分离方法将^131Xe同位素丰度浓缩到90%以上,本研究采用多组分矩形级联算法进行级联计算,分析中间组分的分离特性,研究级联长度、供料位置、级联分流比等参数对分离效果的影响。对分离^131Xe同位素的矩形级联分离方案进行优化,制定生产丰度为90%以上的^131Xe运行方案,通过解决^131Xe同位素分离过程中的级联工况调整与稳定、中间组分浓缩等关键技术,最终经8遍分离获得丰度为93.786%的公斤级^131Xe产品,证明级联生产高丰度^131Xe产品的可行性。 展开更多
关键词 离心法 ^131Xe 中间组分 级联
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Clinicohistopathological implications of phosphoserine 9 glycogen synthase kinase-3β/β-catenin in urinary bladder cancer patients 预览
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作者 Niharika Maurya Rinni Singh +4 位作者 Apul Goel Atin Singhai Uday Pratap Singh Vinita Agrawal Minal Garg 《世界临床肿瘤学杂志(英文版)》 2019年第4期166-182,共17页
BACKGROUND Aberrant activation of phosphorylated form of glycogen synthase kinase-3β[pS9GSK-3β(Serine 9 phosphorylation)] is known to trigger Wnt/β-catenin signal cascade but its clinicohistopathological implicatio... BACKGROUND Aberrant activation of phosphorylated form of glycogen synthase kinase-3β[pS9GSK-3β(Serine 9 phosphorylation)] is known to trigger Wnt/β-catenin signal cascade but its clinicohistopathological implications in bladder carcinogenesis remain unknown. AIM To investigate the diagnostic and prognostic relevance of expressions of pS9GSK- 3β,β-catenin and its target genes in the pathobiology of bladder cancer. METHODS Bladder tumor tissues from ninety patients were analyzed for quantitative expression and cellular localization of pS9GSK-3β by immunohistochemical (IHC) staining. Real time-quantitative polymerase chain reaction and IHC were done to check the expression of β-catenin, Cyclin D1, Snail and Slug at transcriptome and protein level respectively. Clinicohistopathological variables were obtained from histology reports, follow up and OPD visits of patients. Expressions of the markers were statistically correlated with these variables to determine their significance in clinical setting. Results were analysed using SPSS 20.0 software.RESULTS Aberrant (low or no membranous/high nuclear/high cytoplasmic) expression of pS9GSK-3β was noted in 51% patients and found to be significantly associated with tumor stage and tumor grade (P = 0.01 and 0.04;Mann Whitney U test). Thirty one percent tumors exhibited aberrant co-expression of pS9GSK-3β and β–catenin proteins and showed strong statistical association with tumor stage, tumor type, smoking/tobacco chewing status (P = 0.01, 0.02 and 0.04, Mann- Whitney U test) and shorter overall survival probabilities of patients (P = 0.02;Kaplan Meier test). Nuclear immunostaining of Cyclin D1 in tumors with altered pS9GSK-3β/β–catenin showed relevance with tumor stage, grade and type. CONCLUSION β–catenin and pS9GSK-3β proteins are identified as markers of diagnostic/prognostic significance in disease pathogenesis. Observed histopathological association of Cyclin D1 identifies it as marker of potential relevance in tumors with altered pS9GSK-3β/β-cateni 展开更多
关键词 PATHOBIOLOGY Target GENES Tumor stage and grade Wnt/β–catenin signal CASCADE UROTHELIAL carcinoma of BLADDER
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基于二次流控制的变径倒角设计与优化
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作者 张旭阳 陈榴 戴韧 《动力工程学报》 CAS CSCD 北大核心 2019年第6期433-440,共8页
基于Langston叶栅的数值模拟结果,分析了不同半径均匀倒角模型的流动特征,综合评估了倒角半径对叶栅不同位置流动的影响,据此设计并优化了变径倒角结构。结果表明:叶栅前缘倒角半径增大使前缘分流能力增强,马蹄涡强度减小;叶栅中后部大... 基于Langston叶栅的数值模拟结果,分析了不同半径均匀倒角模型的流动特征,综合评估了倒角半径对叶栅不同位置流动的影响,据此设计并优化了变径倒角结构。结果表明:叶栅前缘倒角半径增大使前缘分流能力增强,马蹄涡强度减小;叶栅中后部大半径倒角的采用使得二次流强度增大,叶栅出口损失增大;使用变径倒角后,马蹄涡和通道涡强度减小,沿流向的总压损失系数增长受到抑制,熵增率较低,流动效果得到改善。 展开更多
关键词 叶栅 二次流 变径倒角 Kriging代理模型
Recent applications of radical cascade reaction in the synthesis of functionalized 1-indenones
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作者 Yinli Zhang Kai Sun +3 位作者 Qiyan Lv Xiaolan Chen Lingbo Qua Bing Yu 《中国化学快报:英文版》 SCIE CAS CSCD 2019年第7期1361-1368,共8页
1-Indenones are important scaffolds in natural products, biologically active molecules as well as functional materials. Recently, radical cascade cyclization has emerged as an efficient and powerful strategy for the c... 1-Indenones are important scaffolds in natural products, biologically active molecules as well as functional materials. Recently, radical cascade cyclization has emerged as an efficient and powerful strategy for the construction of valuable and versatile functionalized 1-indenones. In this review, the recent advances of this rapidly growing area were summarized. The selected examples have been classified according to the type of reaction substrates such as 1,3-diarylpropynones, 2-alkynylbenzonitriles, arylpropynols, 1,5-enynes and 2-alkynylated bromocinnamates. 展开更多
关键词 RADICAL CASCADE reaction 1 3-Diarylpropynones 2-Alkynylbenzonitriles Arylpropynols 1-Indenones
基于级联H桥的光伏组件设计与研究 预览
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作者 李翔 张延迟 +1 位作者 解大 赵博文 《电力电子技术》 CSCD 北大核心 2019年第4期77-81,共5页
设计了级联H桥光伏组件结构,包含光伏电池模块、具有惯性能量环节的Boost/Buck模块、链式H桥模块。介绍了最大功率点跟踪(MPPT)控制算法和链式级联H桥控制算法,给出全链12H桥和缺链11H桥的控制角度表,并分析输出电压变化对有功无功的影... 设计了级联H桥光伏组件结构,包含光伏电池模块、具有惯性能量环节的Boost/Buck模块、链式H桥模块。介绍了最大功率点跟踪(MPPT)控制算法和链式级联H桥控制算法,给出全链12H桥和缺链11H桥的控制角度表,并分析输出电压变化对有功无功的影响。在EMTP仿真软件中搭建12H桥级联模型,验证H桥级联输出的可能性,并证明其谐波含量小、电能质量高。最后设计制作了链式级联光伏板,表明可以平稳地输出交流电,并与传统光伏组件的日发电量进行对比,证明其发电量多、追踪辐照度性能良好。 展开更多
关键词 光伏组件 最大功率点跟踪 级联
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相变蓄热技术应用于采暖的研究现状 预览
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作者 李斯 苑翔 赵飞 《节能》 2019年第3期24-27,共4页
随着我国电力行业发展迅速,用电时间集中、峰谷差距大的问题开始显露出来。相变蓄热技术具有蓄热量大、温度恒定的优点,是解决用电峰谷差距大的有效手段,在国内外得到了广泛的研究与应用。结合3种蓄热方式,对应用在采暖方面的相变蓄热... 随着我国电力行业发展迅速,用电时间集中、峰谷差距大的问题开始显露出来。相变蓄热技术具有蓄热量大、温度恒定的优点,是解决用电峰谷差距大的有效手段,在国内外得到了广泛的研究与应用。结合3种蓄热方式,对应用在采暖方面的相变蓄热技术做出综述,分别介绍中低温相变蓄热技术、梯级相变蓄热技术和相变蓄热地板辐射供暖技术,指出相变蓄热技术应用于采暖方面的研究目标和方向。 展开更多
关键词 中低温 梯级 地板辐射 蓄热
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Rydberg electromagnetically induced transparency and Autler–Townes splitting in a weak radio-frequency electric field
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作者 郝丽萍 薛咏梅 +3 位作者 樊佳蓓 焦月春 赵建明 贾锁堂 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第5期80-84,共5页
We utilize an electromagnetically induced transparency(EIT) of a three-level cascade system involving Rydberg state in a room-temperature cell, formed with a cesium 6 S1/2–6 P3/2–66 S1/2 scheme, to investigate the A... We utilize an electromagnetically induced transparency(EIT) of a three-level cascade system involving Rydberg state in a room-temperature cell, formed with a cesium 6 S1/2–6 P3/2–66 S1/2 scheme, to investigate the Autler–Townes(AT)splitting resulting from a 15.21-GHz radio-frequency(RF) field that couples the |66 S1/2〉→ |65 P1/2> Rydberg transition.The radio-frequency electric field induced AT splitting, γAT, is defined as the peak-to-peak distance of an EIT-AT spectrum.The dependence of AT splitting γAT on the probe and coupling Rabi frequency, Ωp and Ωc, is investigated. It is found that the EIT-AT splitting strongly depends on the EIT linewidth that is related to the probe and coupling Rabi frequency in a weak RF-field regime. Using a narrow linewidth EIT spectrum would decrease the uncertainty of the RF field measurements.This work provides new experimental evidence for the theoretical framework in [J. Appl. Phys. 121, 233106(2017)]. 展开更多
关键词 RYDBERG electromagnetically induced transparency-Autler–Townes (EIT-AT) cascade FOUR-LEVEL atom RADIO-FREQUENCY (RF) electric field
基于级联结构的低抖动小数分频频率综合器研究
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作者 冯向明 曲明 刘林海 《微电子学与计算机》 北大核心 2019年第1期90-94,共5页
为了更好的抑制由差分积分调制器(DSM,Delta-sigma modulator)引起的量化噪声、降低小数分频时钟源的时钟抖动,本文提出了一种基于双锁相环级联的抖动消除技术.通过前级整数分频锁相环的倍频提升后级小数分频锁相环DSM的工作频率,抑制... 为了更好的抑制由差分积分调制器(DSM,Delta-sigma modulator)引起的量化噪声、降低小数分频时钟源的时钟抖动,本文提出了一种基于双锁相环级联的抖动消除技术.通过前级整数分频锁相环的倍频提升后级小数分频锁相环DSM的工作频率,抑制系统的量化噪声;针对后级参考频率过高,引发相差转化困难的问题,本文提出一种新型的高速电荷泵,在不增加功耗的前提下更好地实现电流的动态匹配.基于180nm CMOS工艺完成级联系统设计,仿真结果显示系统输出频率范围为3~4G,抖动为137fs,功耗为47.7mW. 展开更多
关键词 低抖动 级联 双环锁相环 量化噪声
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