期刊文献+
共找到4,932篇文章
< 1 2 247 >
每页显示 20 50 100
基于PLC及PN网络的变频器控制研究
1
作者 吕栋腾 任源博 《设备管理与维修》 2025年第12期42-44,共3页
以某生产线加工单元为研究对象,对电机调速控制系统进行了优化设计和选型配置。结合使用场景和系统控制要求,以PLC作为主控制器,通过PN网络实现对变频器的控制,使用TIA博途软件进行硬件组态和程序设计。该系统经综合调试,运行稳定可靠,... 以某生产线加工单元为研究对象,对电机调速控制系统进行了优化设计和选型配置。结合使用场景和系统控制要求,以PLC作为主控制器,通过PN网络实现对变频器的控制,使用TIA博途软件进行硬件组态和程序设计。该系统经综合调试,运行稳定可靠,对电机调速控制系统设计具有一定参考价值。 展开更多
关键词 调速系统 PLC 变频器 pn网络
在线阅读 下载PDF
Li_(x)Ni_(1–x)O薄膜物性调控及基于Li_(x)Ni_(1–x)O的透明pn结整流效应
2
作者 王磊 周同 +3 位作者 华恩达 刘忠良 李兵 刘亲壮 《物理学报》 北大核心 2025年第9期284-291,共8页
透明导电氧化物(TCO)是光电子学中的关键材料,与n型TCO相比,关于p型TCO材料的选择较少,其中NiO作为典型的p型TCO材料具有研发透明光电子器件的潜力.本文使用脉冲激光沉积,在MgO(001)衬底上成功地得到了不同厚度和Li掺杂浓度的Li_(x)Ni_(... 透明导电氧化物(TCO)是光电子学中的关键材料,与n型TCO相比,关于p型TCO材料的选择较少,其中NiO作为典型的p型TCO材料具有研发透明光电子器件的潜力.本文使用脉冲激光沉积,在MgO(001)衬底上成功地得到了不同厚度和Li掺杂浓度的Li_(x)Ni_(1-x)O薄膜.结果表明,厚度和Li掺杂的增加都显著地降低了薄膜的电阻率,并且厚度为50 nm与3%Li掺杂时,薄膜的带隙最大.在薄膜厚度与Li掺杂浓度对其物性调控研究的基础上,选择带隙最大的p型Li_(x)Ni_(1-x)O与n型La掺杂ASnO_(3)薄膜构造了透明电子器件.Ⅰ-Ⅴ测试证实了该透明电子器件的整流特性以及基于透明导电材料pn结的成功构造.这项工作通过将p型NiO与n型ASnO_(3)集成,拓展了透明电子器件的研究与潜在应用. 展开更多
关键词 透明导电氧化物 薄膜 掺杂 pn
在线阅读 下载PDF
帕米尔高原及邻区上地幔顶部Pn波速度和各向异性联合成像
3
作者 刘嘉鑫 裴顺平 郭一村 《地震地质》 北大核心 2025年第2期547-560,共14页
帕米尔高原位于印度-欧亚碰撞带西端,研究帕米尔高原及其周边地区的上地幔的速度和各向异性结构对于认识陆-陆碰撞的构造变形特征及动力学机制具有重要意义。Pn波的射线路径集中在上地幔顶部,其横向速度变化能够显示上地幔构造活动差异... 帕米尔高原位于印度-欧亚碰撞带西端,研究帕米尔高原及其周边地区的上地幔的速度和各向异性结构对于认识陆-陆碰撞的构造变形特征及动力学机制具有重要意义。Pn波的射线路径集中在上地幔顶部,其横向速度变化能够显示上地幔构造活动差异,而其方位各向异性结构则能够显示出地幔物质的运动及形变特征。文中利用363 414个Pn波到时数据,通过对Pn波到时进行层析成像,获得了帕米尔高原及其邻近区域上地幔顶部的高分辨率地震波速度和各向异性图像。层析成像结果与地质构造显示出明显的相关性,主要结果表明:1)帕米尔高原、天山、兴都库什、西昆仑、阿尔金山等构造活动区的Pn波速较低,而印度板块、塔里木盆地、塔吉克盆地、准噶尔盆地、费尔干纳盆地等古老稳定地块显示出高Pn波速度特征。2)印度-欧亚板块碰撞产生较强的Pn波各向异性,在帕米尔高原碰撞区两侧的印度板块、塔里木盆地和塔吉克盆地,各向异性方向与板块运动方向一致,而在碰撞区的中间部位,各向异性方向与最大压应力方向及地壳相对运动方向几乎垂直,可能是由于碰撞带上地幔的纯剪切变形所致。天山两侧也存在类似的特征。 展开更多
关键词 帕米尔高原 上地幔顶部 pn 速度和各向异性
在线阅读 下载PDF
Impact of Oxygen Vacancy on Performance of Amorphous InGaZnO Based Schottky Barrier Diode 被引量:1
4
作者 JIA Bin TONG Xiaowen +3 位作者 HAN Zikang QIN Ming WANG Lifeng HUANG Xiaodong 《发光学报》 北大核心 2025年第3期412-420,共9页
Rectifying circuit,as a crucial component for converting alternating current into direct current,plays a pivotal role in energy harvesting microsystems.Traditional silicon-based or germanium-based rectifier diodes hin... Rectifying circuit,as a crucial component for converting alternating current into direct current,plays a pivotal role in energy harvesting microsystems.Traditional silicon-based or germanium-based rectifier diodes hinder system integration due to their specific manufacturing processes.Conversely,metal oxide diodes,with their simple fabrication techniques,offer advantages for system integration.The oxygen vacancy defect of oxide semiconductor will greatly affect the electrical performance of the device,so the performance of the diode can be effectively controlled by adjusting the oxygen vacancy concentration.This study centers on optimizing the performance of diodes by modulating the oxygen vacancy concentration within InGaZnO films through control of oxygen flows during the sputtering process.Experimental results demonstrate that the diode exhibits a forward current density of 43.82 A·cm^(−2),with a rectification ratio of 6.94×10^(4),efficiently rectifying input sine signals with 1 kHz frequency and 5 V magnitude.These results demonstrate its potential in energy conversion and management.By adjusting the oxygen vacancy,a methodology is provided for optimizing the performance of rectifying diodes. 展开更多
关键词 INGAZNO schottky barrier diode oxygen vacancy rectifying performance
在线阅读 下载PDF
GaN PN结的耗尽区宽度研究
5
作者 孙辰洋 杨沛珑 +1 位作者 刘波 汪莱 《大学物理》 2025年第4期21-26,共6页
耗尽区宽度是PN结一项基本参数.在固体物理教科书中,耗尽宽度的计算通常仅限于Si和Ge等材料,缺乏对GaN等宽带隙半导体材料PN结的分析.耗尽区宽度与耗尽区电荷密度息息相关.Si、Ge材料的杂质电离能很低,常温下完全电离,耗尽区电荷密度显... 耗尽区宽度是PN结一项基本参数.在固体物理教科书中,耗尽宽度的计算通常仅限于Si和Ge等材料,缺乏对GaN等宽带隙半导体材料PN结的分析.耗尽区宽度与耗尽区电荷密度息息相关.Si、Ge材料的杂质电离能很低,常温下完全电离,耗尽区电荷密度显然等于杂质浓度.而p-GaN中受主杂质Mg的电离能约220~270 MeV,常温下部分电离.所以,GaN PN结耗尽区宽度将由杂质浓度与电离程度共同决定.本文首先计算了GaN材料中不同杂质在不同浓度下的电离程度.结果表明,为获得足够空穴浓度,p-GaN重掺杂至10^(19) cm^(-3)的条件下,Mg电离程度确实很低.然后,利用一款基于Scharfetter-Gummel法求解漂移扩散方程的开源求解器仿真计算得出GaN PN结耗尽区宽度、杂质电离程度等重要参数.根据仿真结果,GaN PN结耗尽区中杂质电离程度大幅提升.因此,可以使用掺杂浓度近似计算GaN PN结耗尽区宽度.本文的研究补充了固体物理教材中关于GaN PN结的内容,有助于后续课程的学习. 展开更多
关键词 GAN 杂质电离 pn 耗尽区宽度
在线阅读 下载PDF
PN/A-ICCOMBR系统长期停置后的恢复和稳定运行
6
作者 高洁 苑宏英 +1 位作者 王宏斌 肖柯 《天津城建大学学报》 2025年第4期270-277,共8页
本研究利用自建的一体式部分硝化厌氧氨氧化工艺,研究了长期停置后PN/A-ICCOMBR系统的恢复和稳定运行.研究表明,控制曝气量与进水氨氮浓度是停置系统恢复以及维持稳定运行的关键措施.当系统停置130 d后,温度35℃,水力停留时间(HRT)16 h... 本研究利用自建的一体式部分硝化厌氧氨氧化工艺,研究了长期停置后PN/A-ICCOMBR系统的恢复和稳定运行.研究表明,控制曝气量与进水氨氮浓度是停置系统恢复以及维持稳定运行的关键措施.当系统停置130 d后,温度35℃,水力停留时间(HRT)16 h,采用低氨氮浓度(150 mg·L^(-1))进水,逐渐提高进水氨氮浓度到400 mg·L^(-1),运行55 d后,进水总氮负荷(NLR)0.6 gN·(L·d)^(-1)、总氮去除负荷(NRR)0.43 gN·(L·d)^(-1)、氨氧化率(AOR)0.22 gN·(L·d)^(-1)、总氮(TN)去除率逐步提高到70%以上.之后,在HRT16 h、温度35℃、进水氨氮浓度300 mg·L^(-1)、NLR0.45 gN·(L·d)^(-1)条件下,运行PN/A-ICCOMBR系统120 d,期间出现氨氮累积时,将曝气量从0.4 L·min^(-1)逐渐增加至0.8 L·min^(-1),溶解氧(DO)上升至2.1 mg·L^(-1),经过40天,出水氨氮浓度由125.2 mg·L^(-1)减少到10 mg·L^(-1),AOR由0.15 gN·(L·d)^(-1)增长至0.25 gN·(L·d)^(-1),NRR由0.22 gN·(L·d)^(-1)提高至0.40 gN·(L·d)^(-1),TN去除率超过88%. 展开更多
关键词 pn/A-ICCOMBR 厌氧氨氧化 稳定运行 曝气量 长期停置
在线阅读 下载PDF
AnMBR-PN/A处理甲胺废水工况优化及能耗评价
7
作者 邓萱 陈松 +6 位作者 赵鹤翔 杜博文 杨俞 付静薇 李倩 李玉友 陈荣 《中国环境科学》 北大核心 2025年第10期5517-5524,共8页
构建了厌氧膜生物反应器-部分硝化/厌氧氨氧化(AnMBR-PN/A)系统,研究其处理甲胺废水的工况并对实验效果与能耗、碳排进行评价.研究表明,AnMBR处理甲胺废水的最佳工况HRT为8h,PN/A段HRT为9h时,AnMBR-PN/A体系COD去除率超95%,总氮去除率超... 构建了厌氧膜生物反应器-部分硝化/厌氧氨氧化(AnMBR-PN/A)系统,研究其处理甲胺废水的工况并对实验效果与能耗、碳排进行评价.研究表明,AnMBR处理甲胺废水的最佳工况HRT为8h,PN/A段HRT为9h时,AnMBR-PN/A体系COD去除率超95%,总氮去除率超86%,出水氨氮浓度低于5mg/L,总氮浓度低于15mg/L,达到一级A标准.在最优工况下使用经验公式对体系的能耗和CO_(2)排放进行计算评估,与A^(2)/O工艺相比,AnMBR-PN/A的净能量潜力为0.72,实现了部分能量的回收再利用,同时,AnMBR-PN/A产生的能源气体还具有显著的经济效益.综上,AnMBR-PN/A工艺具有节能减排与降低污水处理成本等多重优势,为实现环境与经济效益的双赢提供了有力支持. 展开更多
关键词 厌氧膜生物反应器 部分硝化/厌氧氨氧化 甲胺废水 物料衡算 能耗分析
在线阅读 下载PDF
基于C链分布的乙醇汽油PN排放特性分析
8
作者 王长卉 孙运才 郭孔鲁 《炼油与化工》 2025年第4期38-41,共4页
随着双碳政策推行,节能减排仍是当前之重。乙醇燃料在中期减排替代过程中占有举足轻重的地位。乙醇燃料组分对于GDI发动机的PN排放的影响重大。基于1款国Ⅵ发动机(未配备GPF)对不同组分的乙醇燃油进行测试分析,结果表明,气态排放中的TH... 随着双碳政策推行,节能减排仍是当前之重。乙醇燃料在中期减排替代过程中占有举足轻重的地位。乙醇燃料组分对于GDI发动机的PN排放的影响重大。基于1款国Ⅵ发动机(未配备GPF)对不同组分的乙醇燃油进行测试分析,结果表明,气态排放中的THC排放与PN排放呈现正相关,这主要是由于未燃HC是冷凝易形成核态颗粒物,从而导致PN排放的增加;乙醇汽油中降低C_(7)及以下碳数的链烷烃将有助减少PN排放,而C_(7)^(+)的链烷烃是有助于燃料燃烧和降低PN排放;降低乙醇汽油中C_(8)^(+)芳烃的占比将有效减少PN排放。 展开更多
关键词 乙醇 pn排放 相关性 碳分布
在线阅读 下载PDF
基于超声影像组学及深度神经网络预测甲状腺乳头状癌pN分期
9
作者 周洁丽 武林娟 +2 位作者 张鹏天 彭艳侠 韩冬 《肿瘤防治研究》 2025年第2期151-155,共5页
目的基于超声影像组学及深度神经网络(DNN)预测甲状腺乳头状癌(PTC)pN分期的准确性。方法回顾性收集经病理确诊的PTC患者375例(训练集261例,测试集114例)。将无颈部淋巴结转移定义为pN0,中央区淋巴结转移定义为pN1a,颈侧区淋巴结转移定... 目的基于超声影像组学及深度神经网络(DNN)预测甲状腺乳头状癌(PTC)pN分期的准确性。方法回顾性收集经病理确诊的PTC患者375例(训练集261例,测试集114例)。将无颈部淋巴结转移定义为pN0,中央区淋巴结转移定义为pN1a,颈侧区淋巴结转移定义为pN1b。由超声科医师手动分割PTC的感兴趣区(ROI)并提取1899个影像组学特征。采用最小绝对收缩与选择算子(LASSO)对上述影像组学特征进行降维。基于H2O深度学习平台在训练集构建预测PTC pN分期的DNN模型,并在测试集验证最优模型准确性。结果pN0期患者153例,pN1a期131例,pN1b期91例。每个PTC的影像组学特征经LASSO回归筛选出15个影像组学特征。基于该15个影像组学特征构建的最优DNN模型在训练集及测试集的准确性分别为85.82%及81.57%。结论PTC的超声影像组学预测pN分期的准确性较高,有为患者自动化N分期的潜力。 展开更多
关键词 甲状腺癌 乳头状 超声检查 pn分期 预测 淋巴结
暂未订购
城市污水PN/A工艺中NOB抑制的挑战与对策研究进展
10
作者 任核葶 刘浩杰 《工业水处理》 北大核心 2025年第5期38-46,共9页
短程硝化-厌氧氨氧化(PN/A)工艺因节省曝气能耗、无需外加碳源及污泥产量少等优势,成为城市污水生物脱氮工艺的研究热点。城市污水低温、低氨氮的特性使得PN/A工艺中亚硝酸盐氧化菌(NOB)活性抑制困难,进而影响PN/A系统的脱氮效能及稳定... 短程硝化-厌氧氨氧化(PN/A)工艺因节省曝气能耗、无需外加碳源及污泥产量少等优势,成为城市污水生物脱氮工艺的研究热点。城市污水低温、低氨氮的特性使得PN/A工艺中亚硝酸盐氧化菌(NOB)活性抑制困难,进而影响PN/A系统的脱氮效能及稳定性。综述了城市污水PN/A工艺中NOB抑制的挑战及对应解决策略,包括曝气控制、基于生物膜及颗粒污泥的污泥龄(SRT)控制、基于游离氨(FA)/游离亚硝酸(FNA)的NOB活性抑制、强化氨氧化菌(AOB)和厌氧氨氧化菌(AnAOB)活性,以及多种抑制策略联合等。为助力主流PN/A工艺运行调控提供了新思路,并指出深化基础理论研究、开发新型组合工艺强化对NOB的抑制以及提升脱氮性能的稳定性是未来的发展方向。 展开更多
关键词 城市污水 短程硝化-厌氧氨氧化工艺 亚硝酸盐氧化菌抑制 氨氧化菌 亚硝酸盐积累
在线阅读 下载PDF
Schottky junction coupling with metal size effect for the enhancement of photocatalytic nitrate reduction
11
作者 Xuemeng Sun Jianan Liu +2 位作者 Qi Li Cheng Wang Baojiang Jiang 《Chinese Journal of Catalysis》 2025年第6期358-367,共10页
Nitrate pollution poses a significant environmental challenge,and photocatalytic nitrate reduction has garnered considerable attention due to its efficiency and environmental advantages.Among these,the development of ... Nitrate pollution poses a significant environmental challenge,and photocatalytic nitrate reduction has garnered considerable attention due to its efficiency and environmental advantages.Among these,the development of Schottky junctions shows considerable potential for practical applications.However,the impact of metal nanoparticle size within Schottky junctions on photocatalytic nitrate reduction remains largely unexplored.In this study,we propose a novel method to modulate metal nanoparticle size within Schottky junctions by controlling light intensity during the photodeposition process.Smaller Au nanoparticles were found to enhance electron accumulation at active sites by promoting charge transfer from COF to Au,thereby improving internal electron transport.Additionally,the Schottky barrier effectively suppressed reverse electron transfer while enhancing NO_(3)^(–)adsorption and activation.The Au_(2-)COF exhibited remarkable nitrate reduction performance,achieving an ammonia yield of 382.48μmol g^(–1)h^(–1),5.7 times higher than that of pure COF.This work provides novel theoretical and practical insights into using controlled light intensity to regulate metal nanoparticle size within Schottky junctions,thereby enhancing photocatalytic nitrate reduction. 展开更多
关键词 schottky junction Nitrate reduction PHOTOCATALYSIS Covalent organic frameworks
在线阅读 下载PDF
一种基于对称PN码设计的时间同步系统及Simulink仿真
12
作者 杨鹏 郗波 张恒 《无线电通信技术》 北大核心 2025年第4期870-876,共7页
针对无线通信系统易受噪声干扰导致时间同步不准,接收性能较差的问题,提出了一种基于对称伪噪声(Pseudo-Noise,PN)码设计的时间同步系统,应用Simulink软件完成通信全链路仿真设计。基于伪随机序列(PN码)的自相关特性提出了极性对称的PN... 针对无线通信系统易受噪声干扰导致时间同步不准,接收性能较差的问题,提出了一种基于对称伪噪声(Pseudo-Noise,PN)码设计的时间同步系统,应用Simulink软件完成通信全链路仿真设计。基于伪随机序列(PN码)的自相关特性提出了极性对称的PN码,设计了基于对称PN码的Simulink时间同步系统,以8PSK为调制解调方式,仿真了波形生成、最佳采样、符号同步、数据解调等全链路通信过程。系统基于PN码对称特性提出了增强型滑窗定位算法以提高自相关峰幅值,降低噪声干扰导致的同步字误捕获概率。仿真结果表明,在同等噪声干扰条件下,相比于单极性PN码和Walsh码设计方式,所提时间同步系统具有更高的帧同步准确率,接收端误码率性能具有2 dB以上的显著提升。 展开更多
关键词 对称伪噪声码 同步 最佳采样 8PSK SIMULINK仿真
在线阅读 下载PDF
Trimetallic MOFs derived NiFe_(2)O_(4)/MoNi_(4)-NC Schottky heterojunctions with abundant defects and dielectric-magnetic coupling for electromagnetic response
13
作者 Ya Ning Xiao Jiang +2 位作者 Jun Huang Yanfeng Gao Xiaojun Zeng 《Journal of Materials Science & Technology》 2025年第10期1-13,共13页
There is limited research reported on the multiple loss mechanism of electromagnetic waves(EMW)and the development of interface models.Dielectric loss and magnetic loss,as the two primary attenuation mechanisms in EMW... There is limited research reported on the multiple loss mechanism of electromagnetic waves(EMW)and the development of interface models.Dielectric loss and magnetic loss,as the two primary attenuation mechanisms in EMW absorbers,still pose challenges,especially in elucidating the correlation between composition,morphology,interface,and performance.Here,we construct 3D hierarchical porous conducting network structures and Schottky heterojunctions(MoNi_(4)@NC-NiFe_(2)O_(4)@NC)with a high density of defects,using trimetallic NiMoFe-MOFs.Synergistic enhancement of the dielectric and magnetic losses is realized through manipulation of the defects,interfaces,phase engineering,and magnetic resonance.In particular,the even dispersion of magnetic MoNi_(4) and NiFe_(2)O_(4)nanoparticles(NPs)within the carbon matrix triggers the creation of multiple heterogeneous interfaces.These inseparable interfaces,along with oxygen vacancies,play a role in enhancing dielectric polarization,while the closely spaced interactions among magnetic units contribute to magnetic loss.After optimizing the interfacial structure,NiFe_(2)O_(4)/MoNi_(4)-NC exhibits remarkable EMW absorption properties.A reflection loss(RL)value of-67.91 dB can be achieved at an ultra-thin thickness of 1.95 mm,and the effective absorption bandwidth(EAB,RL≤-10 dB)is as high as 5.76 GHz.Furthermore,we conducted radar scattering cross-section(RCS)simulations using computer simulation technology(CST)software,which revealed that NiFe_(2)O_(4)/MoNi_(4)-NC exhibits an RCS reduction value of 39.1 dB m^(2).Hence,this work provides comprehensive guidance for the construction of Schottky heterojunctions for lightweight EMW absorbers from a mechanistic point of view. 展开更多
关键词 Trimetallic NiMoFe-MOFs Multiple loss mechanisms Heterogeneous interfaces schottky heterojunctions Electromagnetic response
原文传递
Optimizing the Schottky barrier in AuAg alloy decorated TiO_(2)nanofibers to enhance hot-electron-induced CO_(2)reduction
14
作者 Na Lu Tingting Pang +7 位作者 Xuedong Jing Yongan Zhu Linqun Yu Sining Ben Yuchan Song Shiwen Du Wei Lu Zhenyi Zhang 《Chinese Journal of Structural Chemistry》 2025年第8期71-80,共10页
Plasmon-induced hot electron can transfer from noble metal to its cohesive semiconductor in their heterostructure to initiate the photocatalytic reaction upon resonance excitation.However,the co-excitation of semicond... Plasmon-induced hot electron can transfer from noble metal to its cohesive semiconductor in their heterostructure to initiate the photocatalytic reaction upon resonance excitation.However,the co-excitation of semiconductor in the heterostructure would also lead to the inversus transfer of photo-electron from semiconductor to noble metal,which inevitably limits the use of active electrons.After co-excitation of both localized surface plasmon resonance(LSPR)of noble metal and interband transition of semiconductor,the interfacial electron transfer process strongly depends on the energy band configuration of their heterostructure.When the Au content in the AuAg alloy nanoparticles(NPs)changes from 0 to 100 at.%,the interfacial energy band configuration at AuAg NPs/TiO_(2) NPs in the electrospun nanofibers(NFs)shifts from Ohmic to Schottky contacts.Further investigation finds that the optimal Schottky barrier configuration in Au_(0.25)Ag_(0.75)/TiO_(2) NFs can not only boost the plasmon-induced hot electron transfer from Au_(0.25)Ag_(0.75) to TiO_(2) NPs,but also suppresses the backflow of photo-electrons from TiO_(2) to Au_(0.25)Ag_(0.75) NPs in NFs.Thus,upon UV-visible light irradiation,the CO_(2) photo-reduction activity of Au_(0.25)Ag_(0.75)/TiO_(2) NFs is~3 and~2 times higher than that of either Ag/TiO_(2) or Au/TiO_(2) NFs. 展开更多
关键词 Photocatalysis Plasmonic hot-electron injection schottky barrier AuAg alloy CO_(2)reduction
原文传递
反预期信息标记“服了PN了”构式探析
15
作者 王若水 《今古文创》 2025年第14期124-126,共3页
“服了PN了”是反预期标记,根据新信息较于说话人心理预期的高低表达“赞赏或敬佩”“不满或嗔怪”两种不同的语义类型,具有语篇衔接、信息凸显及话轮标记功能。就充当“服了PN了”的填项的可能性来说,存在如下等级:第二人称代词>第... “服了PN了”是反预期标记,根据新信息较于说话人心理预期的高低表达“赞赏或敬佩”“不满或嗔怪”两种不同的语义类型,具有语篇衔接、信息凸显及话轮标记功能。就充当“服了PN了”的填项的可能性来说,存在如下等级:第二人称代词>第三人称代词>第一人称代词>指人/指物专有名词。 展开更多
关键词 反预期 信息标记 服了pn 语用功能
在线阅读 下载PDF
Precision storage lifetime measurements of highly charged heavy ions in the CSRe storage ring using a Schottky resonator
16
作者 Qian Wang Xin-Liang Yan +13 位作者 Guang-Yu Zhu Shahab Sanjari Li-Jun Mao He Zhao Yuri ALitvinov Rui-Jiu Chen Meng Wang Yu-Hu Zhang You-Jin Yuan Jun-Xia Wu Hong-Yang Jiao Yue Yu Zu-Yi Chen Yin-Fang Luo 《Nuclear Science and Techniques》 2025年第1期150-160,共11页
Schottky mass spectrometry utilizing heavy-ion storage rings is a powerful technique for the precise mass and decay half-life measurements of highly charged ions.Owing to the nondestructive ion detection features of S... Schottky mass spectrometry utilizing heavy-ion storage rings is a powerful technique for the precise mass and decay half-life measurements of highly charged ions.Owing to the nondestructive ion detection features of Schottky noise detectors,the number of stored ions in the ring is determined by the peak area in the measured revolution frequency spectrum.Because of their intrinsic amplitude-frequency characteristic(AFC),Schottky detector systems exhibit varying sensitivities at different frequencies.Using low-energy electron-cooled stored ions,a new method is developed to calibrate the AFC curve of the Schottky detector system of the Experimental Cooler Storage Ring(CSRe)storage ring located in Lanzhou,China.Using the amplitude-calibrated frequency spectrum,a notable refinement was observed in the precision of both the peak position and peak area.As a result,the storage lifetimes of the electron-cooled fully ionized^(56)Fe^(26+)ions were determined with high precision at beam energies of 13.7 and 116.4 MeV/u,despite of frequency drifts during the experiment.When electron cooling was turned off,the effective vacuum condition experienced by the 116.4 MeV/u^(56)Fe^(26+)ions was determined using amplitude-calibrated spectra,revealing a value of 2×10^(−10)mbar,which is consistent with vacuum gauge readings along the CSRe ring.The method reported herein will be adapted for the next-generation storage ring of the HIAF facility under construction in Huizhou,China.It can also be adapted to other storage ring facilities worldwide to improve precision and enhance lifetime measurements using many ions in the ring. 展开更多
关键词 Lifetime measurement schottky mass spectrometry Sensitivity response Highly charged heavy ion RESONATOR UH vacuum Nondestructive diagnostics
在线阅读 下载PDF
Influence of a cylindrical PN junction on the propagation characteristics of shear cylindrical waves in a layered piezoelectric semiconductor concentric cylinder structure
17
作者 Ruiyang LIU Xiao GUO +2 位作者 Chunyu XU Zibo WEI Chenxi DING 《Applied Mathematics and Mechanics(English Edition)》 2025年第8期1551-1570,I0024-I0026,共23页
This paper theoretically investigates the influence of a cylindrical PN junction on the propagation characteristics of shear cylindrical waves(SCWs)in an infinitely long piezoelectric semiconductor(PS)concentric cylin... This paper theoretically investigates the influence of a cylindrical PN junction on the propagation characteristics of shear cylindrical waves(SCWs)in an infinitely long piezoelectric semiconductor(PS)concentric cylinder structure.This PS concentric cylinder structure is composed of three regions:an inner PS cylinder,an outer PS cylindrical shell,and a cylindrical PN junction at the interface between the two aforementioned regions.First,the basic equations of the PS concentric cylinder structure are derived,taking into account the coupling of the mechanical displacement,electric potential,and charge carrier perturbation in the cylindrical coordinate system.Next,a mathematical model for the SCWs in this PS concentric cylinder structure is established,utilizing the spectral method and considering the physical characteristics of the cylindrical PN junction.Finally,the dispersion and attenuation curves of the SCWs are numerically calculated to discuss the influence of the interface effect resulting from the cylindrical PN junction.It is found that the existence of a cylindrical PN junction can either reduce or enhance the mechanical-to-electrical energy conversion,which is closely related to the doping mode,doping concentration,and curvature radius of the cylindrical interface.A reasonable design of the aforementioned parameters can optimize the wave motion in acoustic equipment formed by PS media with different frequencies or wavelengths.The construction and resolution of the mathematical model as well as the analysis of physical mechanisms can offer theoretical guidance for improving the efficiency of energy conversion from mechanical energy to electrical energy and optimizing the acoustic performance of energy harvesting devices. 展开更多
关键词 piezoelectric semiconductor(PS) cylindrical pn junction layered cylinder structure dispersion relation spectral method
在线阅读 下载PDF
Research Progress of Panax notoginseng Saponins(PNS)in the Treatment of Cardiovascular Diseases
18
作者 Ziyi LIU Jing XU Jinfeng CHEN 《Medicinal Plant》 2025年第3期92-96,共5页
Panax notoginseng saponins(PNS)is the primary active component of the traditional Chinese medicine P.notoginseng.This compound exhibits a range of pharmacological effects,including anti-inflammatory,antioxidant,and an... Panax notoginseng saponins(PNS)is the primary active component of the traditional Chinese medicine P.notoginseng.This compound exhibits a range of pharmacological effects,including anti-inflammatory,antioxidant,and antiplatelet aggregation properties,as well as the enhancement of microcirculation.The extensive research on the modernization of traditional Chinese medicine has garnered significant attention regarding the application of PNS in the treatment of cardiovascular diseases.Research has demonstrated that PNS interventions significantly improve the pathological progression of cardiovascular disease through synergistic effects involving multiple targets and pathways.This paper summarizes the pharmacological mechanisms,clinical research advancements,safety,and potential adverse reactions associated with PNS in the treatment of cardiovascular diseases,in order to provide theoretical references for future research and practical applications in this field. 展开更多
关键词 PANAX notoginseng SAPONINS (pnS) Cardiovascular diseases PLATELET aggregation Oxidative stress Lipid metabolism MYOCARDIAL fibrosis Inflammatory response CARDIOMYOCYTE
暂未订购
Analysis of the electromechanical coupling characteristics of piezoelectric semiconductor PN junction shell structures
19
作者 Tiqing WANG Feng ZHU +4 位作者 Peng LI Zelin XU Tingfeng MA I.KUZNETSOVA Zhenghua QIAN 《Applied Mathematics and Mechanics(English Edition)》 2025年第6期1167-1186,共20页
Based on the nonlinear drift-diffusion(NLDD)model,the coupled behavior between the mechanical and electrical fields in piezoelectric semiconductor(PS)PN junctions under two typical loading conditions is investigated.T... Based on the nonlinear drift-diffusion(NLDD)model,the coupled behavior between the mechanical and electrical fields in piezoelectric semiconductor(PS)PN junctions under two typical loading conditions is investigated.The governing equations for the general shell structure of the PS PN junction are derived within the framework of virtual work principles and charge continuity conditions.The distributions of the electromechanical coupling field are obtained by the Fourier series expansion and the differential quadrature method(DQM),and the nonlinearity is addressed with the iterative method.Several numerical examples are presented to investigate the effects of mechanical loading on the charge carrier transport characteristics.It is found that the barrier height of the heterojunction can be effectively modulated by mechanical loading.Furthermore,a nonlinearity index is introduced to quantify the influence of nonlinearity in the model.It is noted that,when the concentration difference between the two sides is considerable,the nonlinear results differ significantly from the linear results,thereby necessitating the adoption of the NLDD model. 展开更多
关键词 piezoelectric semiconductor(PS) pn junction shell structures nonlinear drift-diffusion(NLDD)model potential barrier(well)
在线阅读 下载PDF
Dispersion,attenuation,and bandgap of in-plane coupled Bloch waves in piezoelectric semiconductor phononic crystal with PN junction
20
作者 Zibo WEI Peijun WEI +1 位作者 Chunyu XU Xiao GUO 《Applied Mathematics and Mechanics(English Edition)》 2025年第5期813-830,共18页
In this paper,the dispersion,attenuation,and bandgap characteristics of in-plane coupled Bloch waves in one-dimensional piezoelectric semiconductor(PSC)phononic crystals are investigated,emphasizing the influence of p... In this paper,the dispersion,attenuation,and bandgap characteristics of in-plane coupled Bloch waves in one-dimensional piezoelectric semiconductor(PSC)phononic crystals are investigated,emphasizing the influence of positive-negative(PN)junctions.Unlike piezoelectric phononic crystals,the coupled Bloch waves in PSC phononic crystals are attenuated due to their semiconductor properties,and thus the solution of Bloch waves becomes more complicated.The transfer matrix of the phononic crystal unit cell is obtained using the state transfer equation.By applying the Bloch theorem for periodic structures,the dispersion relation of the coupled Bloch waves is derived,and the dispersion,attenuation,and bandgap are obtained in the complex wave number domain.It is found that the influence of the PN junction cannot be neglected.Moreover,the effects of the PN junction under different apparent wave numbers and steady-state carrier concentrations are provided.This indicates the feasibility of adjusting the propagation characteristics of Bloch waves through the regulation of the PN heterojunction. 展开更多
关键词 piezoelectric semiconductor(PSC) phononic crystal positive-negative(pn)junction dispersion and attenuation carrier field transfer matrix
在线阅读 下载PDF
上一页 1 2 247 下一页 到第
使用帮助 返回顶部