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Bidirectional rotating direct-current triboelectric nanogenerator with self-adaptive mechanical switching for harvesting reciprocating motion
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作者 Donghan Lee Joonmin Chae +6 位作者 Sumin Cho Jong Woo Kim Awais Ahmad Mohammad Rezaul Karim Moonwoo La Sung Jea Park Dongwhi Choi 《International Journal of Extreme Manufacturing》 SCIE EI CAS CSCD 2024年第4期324-335,共12页
Amid the growing interest in triboelectric nanogenerators(TENGs)as novel energy-harvesting devices,several studies have focused on direct current(DC)TENGs to generate a stable DC output for operating electronic device... Amid the growing interest in triboelectric nanogenerators(TENGs)as novel energy-harvesting devices,several studies have focused on direct current(DC)TENGs to generate a stable DC output for operating electronic devices.However,owing to the working mechanisms of conventional DC TENGs,generating a stable DC output from reciprocating motion remains a challenge.Accordingly,we propose a bidirectional rotating DC TENG(BiR-TENG),which can generate DC outputs,regardless of the direction of rotation,from reciprocating motions.The distinct design of the BiR-TENG enables the mechanical rectification of the alternating current output into a rotational-direction-dependent DC output.Furthermore,it allows the conversion of the rotational-direction-dependent DC output into a unidirectional DC output by adapting the configurations depending on the rotational direction.Owing to these tailored design strategies and subsequent optimizations,the BiR-TENG could generate an effective unidirectional DC output.Applications of the BiR-TENG for the reciprocating motions of swinging doors and waves were demonstrated by harnessing this output.This study demonstrates the potential of the BiR-TENG design strategy as an effective and versatile solution for energy harvesting from reciprocating motions,highlighting the suitability of DC outputs as an energy source for electronic devices. 展开更多
关键词 direct-current triboelectric nanogenerator mechanical rectification self-adaptive mechanical design harvesting reciprocation motion
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Analyses of nonequilibrium transport in atmospheric-pressure direct-current argon discharge under different modes
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作者 Ziming ZHANG Chuan FANG +2 位作者 Yaoting WANG Lanyue LUO Heping LI 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第11期107-126,共20页
The key plasma parameters under different discharge modes, such as heavy-particle and electron temperatures, electron number density, and nonequilibrium volume of plasmas, play important roles in various applications ... The key plasma parameters under different discharge modes, such as heavy-particle and electron temperatures, electron number density, and nonequilibrium volume of plasmas, play important roles in various applications of gas discharge plasmas. In this study, a self-consistent two-dimensional nonequilibrium fluid model coupled with an external circuit model is established to reveal the mechanisms related to the discharge modes, including the normal glow, abnormal glow,arc, and glow-to-arc transition modes, with an atmospheric-pressure direct-current(DC) argon discharge as a model plasma system. The modeling results show that, under different discharge modes, the most significant difference between the preceding four discharge modes lies in the current and energy transfer processes on the cathode side. On one hand, the current to the cathode surface is mainly delivered by the ions coming from the plasma column under the glow discharge mode due to the low temperature of the solid cathode, whereas the thermionic and secondary electrons emitted from the hot cathode surface play a very important role under the arc mode with a higher cathode surface temperature and higher ion flux toward the cathode. On the other hand, the energy transfer channel on the cathode side changes from mainly heating the solid cathode under the glow mode to simultaneously heating both the solid cathode and plasma column under the arc mode with an increase in the discharge current. Consequently, the power density in the cathode sheath(P_c) was used as a key parameter for judging different discharge modes, and the range of(0.28–1.2) × 10^(12) W m^(-3) was determined as a critical window of P_c corresponding to the glow-to-arc-mode transition for the atmospheric-pressure DC argon discharge, which was also verified by comparison with the experimental results in this study and the data in the previous literature. 展开更多
关键词 atmospheric-pressure plasma direct-current gas discharge discharge mode mode transition power density in cathode sheath
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Constructions and Preliminary HV Conditioning of a Photocathode Direct-Current Electron Gun at IHEP 被引量:3
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作者 李小平 王九庆 +6 位作者 徐金强 裴士伦 肖欧正 何大勇 吕琨 孔祥成 彭晓华 《Chinese Physics Letters》 SCIE CAS CSCD 2017年第7期56-60,共5页
As one of the most important key technologies for future advanced light source based on the energy recovery linac, a photocathode dc electron gun is supported by Institute of High Energy Physics (IHEP) to address th... As one of the most important key technologies for future advanced light source based on the energy recovery linac, a photocathode dc electron gun is supported by Institute of High Energy Physics (IHEP) to address the technical challenges of producing very low ernittance beams at high average current. Construction of the dc gun is completed and a preliminary high voltage conditioning is carried out up to 440 k V. The design, construction and preliminary HV conditioning results for the dc gun are described. 展开更多
关键词 ERL Constructions and Preliminary HV Conditioning of a Photocathode direct-current Electron Gun at IHEP HV
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Anomalous Direct-Current Josephson Effect in Semiconductor Nanowire Junctions
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作者 伍滨和 封许昱 +2 位作者 王超 徐晓峰 王春瑞 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第1期118-122,共5页
We investigate the dc Josephson effect in one-dimensional junctions where a ring conductor is sandwiched between two semiconductor nanowires with proximity-induced superconductivity. Peculiar features of the Josephson... We investigate the dc Josephson effect in one-dimensional junctions where a ring conductor is sandwiched between two semiconductor nanowires with proximity-induced superconductivity. Peculiar features of the Josephson effect arise due to the interplay of spin-orbit interaction and external Zeenmn field. By tuning the Zeeman field orientation, the device can vary from 0 to π junction. Afore importantly, nonzero ,losephson current is possible at zero phase difference across the junction. Although this anomalous Josephson current is not relevant to the topological phase transition, its magnitude can be significantly enhanced whe, n the nanowire, s become topological superconductors where Majorana bound states emerge. Distinct modulation patterns are obtained for the semiconductor nanowires in the topologically trivial and non-trivial phases. These results are useful to probe the topological phase transition in semiconductor nanowire junctions via the dc Josephson effect. 展开更多
关键词 of IS on in for Anomalous direct-current Josephson Effect in Semiconductor Nanowire Junctions SOI
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Effects of the sputtering power on the crystalline structure and optical properties of the silver oxide films deposited using direct-current reactive magnetron sputtering
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作者 郜小勇 张增院 +3 位作者 马姣民 卢景霄 谷锦华 杨仕娥 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第2期370-375,共6页
This paper reports that a series of silver oxide (AgzO) films are deposited on glass substrates by direct-current reactive magnetron sputtering at a substrate temperature of 250 ℃ and an oxygen flux ratio of 15:18... This paper reports that a series of silver oxide (AgzO) films are deposited on glass substrates by direct-current reactive magnetron sputtering at a substrate temperature of 250 ℃ and an oxygen flux ratio of 15:18 by modifying the sputtering power (SP). The AgxO films deposited apparently show a structural evolution from cubic biphased (AgO + Ag20) to cubic single-phased (Ag20), and to biphased (Ag20 + AgO) structure. Notably, the cubic single-phased Ag20 fihn is deposited at the SP = 105 W and an AgO phase with (220) orientation discerned in the Ag^O films deposited using the SP 〉 105 W. The transmissivity and refiectivity of the AgxO films in transparent region decrease with the increase the SP, whereas the absorptivity inversely increases with the increase of the SP. These results may be due to the structural evolution and the increasing film thickness. A redshift of the films' absorption edges determined in terms of Tauc formula clearly occurs from 3.1 eV to 2.73 eV with the increase of the SP. 展开更多
关键词 Ag2O film direct-current reactive magnetron sputtering x-ray diffraction optical prop-erties
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Structural,Morphological and Electrical Properties of In-Doped Zinc Oxide Nanostructure Thin Films Grown on p-Type Gallium Nitride by Simultaneous Radio-Frequency Direct-Current Magnetron Co-Sputtering
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作者 R.Perumal Z.Hassan R.Saravanan 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第6期77-80,共4页
Zinc oxide (ZnO) is one of the most promising and frequently used semiconductor materials. In-doped nanos- tructure ZnO thin films are grown on p-type gallium nitride substrates by employing the simultaneous rf and ... Zinc oxide (ZnO) is one of the most promising and frequently used semiconductor materials. In-doped nanos- tructure ZnO thin films are grown on p-type gallium nitride substrates by employing the simultaneous rf and dc magnetron co-sputtering technique. The effect of In-doping on structural, morphological and electrical properties is studied. The different dopant concentrations are accomplished by varying the direct current power of the In target while keeping the fixed radio frequency power of the ZnO target through the co-sputtering deposition technique by using argon as the sputtering gas at ambient temperature. The structural analysis confirms that all the grown thin films preferentially orientate along the c-axis with the wurtzite hexagonal crystal structure without having any kind of In oxide phases. The presenting Zn, 0 and In elements' chemical compositions are identified with EDX mapping analysis of the deposited thin films and the calculated M ratio has been found to decrease with the increasing In power. The surface topographies of the grown thin films are examined with the atomic force microscope technique. The obtained results reveal that the grown film roughness increases with the In power. The Hall measurements ascertain that all the grown films have n-type conductivity and also the other electrical parameters such as resistivity,mobility and carrier concentration are analyzed. 展开更多
关键词 ZnO of Structural Morphological and Electrical Properties of In-Doped Zinc Oxide Nanostructure Thin Films Grown on p-Type Gallium Nitride by Simultaneous Radio-Frequency direct-current Magnetron Co-Sputtering that by were been In EDX on
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Modeling of Pulsed Direct-Current Glow Discharge
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作者 杜木 郑亚茹 +3 位作者 范宇佳 张楠 刘成森 王德真 《Plasma Science and Technology》 SCIE EI CAS CSCD 2010年第4期447-451,共5页
A self-consistent model was adopted to study the time evolution of low-voltage pulsed DC glow discharge. The distributions of electric field, ion density and electron density in nitrogen were investigated in our simul... A self-consistent model was adopted to study the time evolution of low-voltage pulsed DC glow discharge. The distributions of electric field, ion density and electron density in nitrogen were investigated in our simulation, and the temporal shape of the discharge current was also obtained. Our results show that the dynamic behaviors of the discharge depends strongly on the applied pulse voltage, and the use of higher pulse voltages results in a significantly increase of discharge current and a decrease of discharge delay time. The current-voltage characteristic cMculated by adjusting secondary electron emission coefficient for different applied pulse voltage under the gas pressure of 1 Torr is found in a reasonable agreement with the experimental results. 展开更多
关键词 pulsed direct-current glow discharge plasma processing plasma simulation
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Research on corona discharge suppression of high-voltage direct-current transmission lines based on dielectric-film-covered conductor
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作者 Yuze JIANG Qiying LI +4 位作者 Xuekai ZHANG Diwen JIANG Shiqiang LIU Bangfa PENG Jie LI 《Plasma Science and Technology》 SCIE EI CAS CSCD 2021年第2期64-75,共12页
Corona discharge suppression for high-voltage direct-current(HVDC)transmission lines at line terminals such as converter stations is a subject that requires attention.In this paper,a method based on a conductor covere... Corona discharge suppression for high-voltage direct-current(HVDC)transmission lines at line terminals such as converter stations is a subject that requires attention.In this paper,a method based on a conductor covered with dielectric film is proposed and implemented through a bench-scale setup.Compared with the bare conductor,the corona discharge suppression effect of the dielectric-film-covered conductor under positive polarity is studied from the composite field strength and ion current density using a line-plate experimental device.The influences of film thickness and film material on the corona discharge suppression effect are investigated.The charge accumulation and dissipation characteristics of different film materials are also studied.The results show that the conductor covered with dielectric film has excellent ability to inhibit corona discharge.The ground-level composite field strength of the conductor covered with dielectric film is lower than its nominal field strength,and its ion current density is at the nA m^(−2) level.The corona threshold voltage can be promoted by increasing the film thickness,but the ability to inhibit corona discharge becomes weak.The larger the surface electric field strength,the more charge accumulated,but the faster the charge dissipation rate.Compared with polyvinyl chloride film,cross-linked polyethylene film has stronger charge accumulation ability and slower charge dissipation rate,which can better restrain the corona discharge of HVDC transmission lines. 展开更多
关键词 high-voltage direct-current(HVDC)transmission lines corona discharge suppression dielectric-film-covered conductor composite field strength ion current density
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Three modes of a direct-current plasma jet operated underwater to degrade methylene blue 被引量:5
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作者 Xuechen LI Biao WANG +3 位作者 Pengying JIA Linwei YANG Yaru LI Jingdi CHU 《Plasma Science and Technology》 SCIE EI CAS CSCD 2017年第11期75-81,共7页
A direct-current air plasma jet operated underwater presents three stable modes including an intermittently-pulsed discharge, a periodically-pulsed discharge and a continuous discharge with increasing the power voltag... A direct-current air plasma jet operated underwater presents three stable modes including an intermittently-pulsed discharge, a periodically-pulsed discharge and a continuous discharge with increasing the power voltage. The three discharge modes have different appearances for the plasma plumes. Moreover, gap voltage-current characteristics indicate that the continuous discharge is in a normal glow regime. Spectral lines from reactive species(OH, N2, N2^+, Hα,and O) have been revealed in the emission spectrum of the plasma jet operated underwater.Spectral intensities emitted from OH radical and oxygen atom increase with increasing the power voltage or the gas flow rate, indicating that reactive species are abundant. These reactive species cause the degradation of the methylene blue dye in solution. Effects of the experimental parameters such as the power voltage, the gas flow rate and the treatment time are investigated on the degradation efficiency. Results indicate that the degradation efficiency increases with increasing the power voltage, the gas flow rate or the treatment time. Compared with degradation in the intermittently-pulsed mode or the periodically-pulsed one, it is more efficient in the continuous mode, reaching 98% after 21 min treatment. 展开更多
关键词 plasma jet direct current glow discharge plasma degradation methylene blue
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Intelligent algorithm-based maximum power point tracker for an off-grid photovoltaic-powered direct-current irrigation system 被引量:1
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作者 Hussain Attia Maen Takruri Ali Al-Ataby 《Clean Energy》 EI CSCD 2024年第3期48-61,共14页
This research aims to enhance the performance of photovoltaic(PV)systems on a 2-fold basis.Firstly,it introduces an advanced deep artificial neural network algorithm for accurate and fast maximum power point tracking,... This research aims to enhance the performance of photovoltaic(PV)systems on a 2-fold basis.Firstly,it introduces an advanced deep artificial neural network algorithm for accurate and fast maximum power point tracking,ensuring optimal extraction of electrical power from PV arrays.Secondly,it proposes the use of 96-V,2.98-kW direct-current(DC)water pumps for farm irrigation,aiming to improve efficiency,reduce cost and complexity,and overcome challenges associated with connecting faraway farm irrigation systems to the utility grid.In this study,it has been demonstrated that the use of DC pumps greatly improves system performance and efficiency by eliminating the need for isolation transformers,power passive filters and inverters,therefore simplifying the architecture of the system.The efficacy of the proposed methodology is confirmed by MATLAB®/Simulink®simulation results,whereby the proposed algorithm attains a mean squared error of 6.5705×10^(-5)and a system efficiency approaching 99.8%,ensuring a steady voltage under varying load conditions. 展开更多
关键词 artificial neural network photovoltaic arrays maximum power point tracking buck converter direct-current irrigation systems MATLAB/SIMULINK
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经颅直流电刺激对慢性期脑卒中偏瘫患者上肢运动功能的疗效分析 被引量:1
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作者 程欣欣 张玲玲 +5 位作者 刘婉 刘莉 杨永超 高润 朱慧敏 张传文 《医疗卫生装备》 CAS 2024年第2期67-73,共7页
目的:研究双侧经颅直流电刺激(dual-hemispheric transcranial direct current stimulation,Dual-tDCS)对慢性期脑卒中患者上肢运动功能的影响,为治疗慢性期脑卒中上肢功能障碍提供基于神经机制的理论依据。方法:选取某院24例慢性期脑... 目的:研究双侧经颅直流电刺激(dual-hemispheric transcranial direct current stimulation,Dual-tDCS)对慢性期脑卒中患者上肢运动功能的影响,为治疗慢性期脑卒中上肢功能障碍提供基于神经机制的理论依据。方法:选取某院24例慢性期脑卒中上肢运动功能障碍患者,按照随机数字表法将其分为研究组(n=13)和对照组(n=11)。对照组采用tDCS伪刺激联合常规康复治疗,研究组采用Dual-tDCS联合常规康复治疗。治疗前后,采用Fugl-Meyer运动功能评定量表上肢部分(Fugl-Meyer assessment upper limb scale,FMA-UL)及日常生活活动能力(activities of daily living,ADL)测评量表对患者活动能力进行评估。对比治疗前后初级运动皮层(M1区)与全脑功能连接(functional connectivity,FC)的变化。使用SPSS 24.0统计学软件进行数据分析。结果:治疗后,2组患者的FMA-UL、ADL评分比治疗前均显著提高,且研究组评分明显高于对照组,差异有统计学意义(P<0.05)。M1区与全脑FC分析显示,治疗后对照组健侧M1区到患侧枕中回、健侧舌回、健侧角回FC降低(P<0.01);患侧M1区未见FC变化脑区。治疗后研究组健侧M1区到健侧小脑、健侧小脑蚓部FC降低,到患侧中央前回FC增加(P<0.01);患侧M1区到患侧小脑、患侧颞中回FC增加,到健侧中央前回FC降低(P<0.01)。结论:Dual-tDCS对大脑的神经调控作用可改善慢性期卒中患者运动和非运动相关脑区的FC,可能是慢性期脑卒中上肢运动功能障碍的康复机制。 展开更多
关键词 Dual-tDCS 慢性期脑卒中 上肢运动功能障碍 功能连接 偏瘫
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经颅直流电刺激对卒中后传导性失语症患者语言功能的治疗效果研究
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作者 张大华 宋为群 +3 位作者 张甜甜 程亦男 汪洁 赵钰婷 《中国脑血管病杂志》 CAS CSCD 北大核心 2024年第10期678-683,共6页
目的探讨经颅直流电刺激(tDCS)干预左侧大脑外侧裂后部颞顶联合区对卒中后传导性失语症患者语言功能的治疗效果。方法前瞻性连续纳入2021年6月至2024年4月在首都医科大学宣武医院康复医学科治疗的卒中后失语症患者。本研究采用自身交叉... 目的探讨经颅直流电刺激(tDCS)干预左侧大脑外侧裂后部颞顶联合区对卒中后传导性失语症患者语言功能的治疗效果。方法前瞻性连续纳入2021年6月至2024年4月在首都医科大学宣武医院康复医学科治疗的卒中后失语症患者。本研究采用自身交叉随机对照试验,入组患者经西方失语成套测验诊断标准评估为传导性失语。将12例卒中后传导性失语症患者完全随机分为A组(治疗顺序:A期—洗脱期—B期)和B组(治疗顺序:B期—洗脱期—A期),各6例。A期为tDCS真干预联合言语语言训练,B期为tDCS假干预联合言语语言训练,洗脱期仅接受言语语言训练,每期均训练5 d。tDCS阳极为刺激电极,放置于刺激靶点;阴极为参考电极,放置于右侧肩部。tDCS的强度为1.4 mA,真刺激为20 min/次,假刺激仅30 s/次后自动停止,均2次/d,共治疗10次。言语语言训练30 min/次,2次/d,共训练10次。A、B期治疗前和治疗后立即进行复述和视图命名(训练项和非训练项)功能检查,并比较A期与B期治疗前后复述和视图命名(训练项和非训练项)功能评分的差值。结果(1)A组与B组患者性别、年龄、病程、受教育程度的差异均无统计学意义(均P>0.05)。(2)康复治疗前,A组与B组患者复述和视图命名(训练项、非训练项)功能评分的差异均无统计学意义(均P>0.05)。(3)A组与B组内洗脱期治疗前后复述和视图命名(训练项、非训练项)功能评分的差异均无统计学意义(均P>0.05)。(4)与B期治疗前后的差值比较,A期患者治疗前后复述功能、视图命名(训练项)、视图命名(非训练项)功能评分的差值均较高[分别为(6.9±1.4)分比(2.2±1.0)分,t=9.604;(6.2±1.2)分比(1.8±1.1)分,t=9.277;(6.5±1.0)分比(1.5±1.0)分,t=12.247;均P<0.01]。结论初步分析显示,tDCS对左侧大脑外侧裂后部颞顶联合区脑组织的干预可能有助于改善卒中后传导性失语症患者复述和视图命名(训练项和非训练项)能力。本研究样本量较少,结果有待于进一步探讨。 展开更多
关键词 命名不能 失语 传导性 经颅直流电刺激 复述功能 视图命名
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不同电流密度经颅直流电刺激对脑卒中患者上肢运动障碍疗效分析
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作者 张大华 宋为群 +3 位作者 程亦男 袁英 汪洁 马佳妮 《中国现代神经疾病杂志》 CAS 北大核心 2024年第3期188-192,共5页
目的对比分析不同电流密度经颅直流电刺激对脑卒中患者上肢运动障碍的疗效。方法选择2019年3月至2022年6月首都医科大学宣武医院收治的45例脑卒中后上肢运动障碍患者,随机予以低电流密度(0.028 mA/cm2,低密度组)、中等电流密度(0.057 mA... 目的对比分析不同电流密度经颅直流电刺激对脑卒中患者上肢运动障碍的疗效。方法选择2019年3月至2022年6月首都医科大学宣武医院收治的45例脑卒中后上肢运动障碍患者,随机予以低电流密度(0.028 mA/cm2,低密度组)、中等电流密度(0.057 mA/cm2,中密度组)和高电流密度(0.080 mA/cm2,高密度组)电刺激(每组各15例),于治疗前和治疗后1周采用Fugl‑Meyer上肢评价量表(FMA‑UE)和上肢动作研究测验量表(ARAT)评价上肢运动功能,改良Barthel指数(mBI)评价日常生活活动能力。结果不同电流密度组患者治疗后FMA‑UE(F=284.343,P=0.000)、ARAT(F=180.427,P=0.000)和mBI(F=487.159,P=0.000)评分均高于治疗前;各组间FMA‑UE(F=2.293,P=0.000)和ARAT(F=2.572,P=0.000)评分差异有统计学意义,其中高密度组和中密度组FMA‑UE(t=2.426,P=0.029;t=2.140,P=0.035)和ARAT(t=2.537,P=0.024;t=2.353,P=0.028)评分均高于低密度组。结论经颅直流电刺激可有效改善脑卒中患者上肢运动功能,尤以电流密度0.057和0.080 mA/cm2效果更佳。 展开更多
关键词 经颅直流电刺激 卒中 运动障碍 上肢
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基于钳位型断路器的柔直系统控保协同技术
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作者 薛士敏 陈文杰 +3 位作者 张君婷 李翔宇 李博通 陈晓龙 《天津大学学报(自然科学与工程技术版)》 EI CAS CSCD 北大核心 2024年第7期729-740,共12页
柔性直流系统以其在输电领域的巨大优势而获得广泛应用.但在直流系统中,短路故障的强冲击性与电力电子器件的脆弱性之间的矛盾异常尖锐,现有保护策略难以同时满足高速动性与高可靠性的要求.本文从控保协同思想出发,基于一种电压钳位原... 柔性直流系统以其在输电领域的巨大优势而获得广泛应用.但在直流系统中,短路故障的强冲击性与电力电子器件的脆弱性之间的矛盾异常尖锐,现有保护策略难以同时满足高速动性与高可靠性的要求.本文从控保协同思想出发,基于一种电压钳位原理的直流断路器,提出一种新的故障处理模式,初步探究在柔直系统中控制与保护深度融合的可能性.当发生短路故障时,投入断路器和换流器相配合的限流功能,一方面限制电力电子器件的过流,解决其脆弱性问题;另一方面为保护提供边界,辅助实现故障的快速定位.在甄别出故障线路后,利用断路器的故障切除功能将故障隔离.此方案同时实现了故障限流、保护边界和故障切除3项功能,可有效缓减由于模块化多电平换流器(modular multilevel converter,MMC)器件脆弱性所带来的一系列保护问题.在PSCAD/EMTDC中搭建四端双极柔性直流电网模型,仿真结果表明,本控保协同方案能在5 ms内准确识别并隔离故障线路,而且具有较强的耐受过渡电阻能力. 展开更多
关键词 柔性直流系统 控保协同 直流断路器 故障限流 故障定位
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模块化高压大容量DC/DC变换器综述 被引量:2
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作者 张书鑫 赵若凡 刘鸿鹏 《东北电力大学学报》 2024年第1期52-60,共9页
随着新能源发电占比增加和电网规模的不断扩大,直流输电系统的容量不断提升,含有不同电压等级的直流电网是未来发展的必然趋势。在此背景下,DC/DC变换器作为直流电网关键设备,在多电压等级互联场景中发挥着重要作用。文中首先对已有的... 随着新能源发电占比增加和电网规模的不断扩大,直流输电系统的容量不断提升,含有不同电压等级的直流电网是未来发展的必然趋势。在此背景下,DC/DC变换器作为直流电网关键设备,在多电压等级互联场景中发挥着重要作用。文中首先对已有的模块化高压大容量DC/DC变换器进行归纳、分类和比较,然后阐述了目前模块化高压大容量DC/DC变换器的拓扑结构、工作原理与特点,并针对其特点提出了不同变换器的适用场景,最后对未来的研究方向提出了建议。 展开更多
关键词 柔性直流输电 直流电网 模块化多电平换流器 模块化高压大容量DC/DC变换器
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P300与慢性意识障碍患者经颅直流电刺激响应的相关性研究
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作者 张晔 李瑞 +2 位作者 万小萍 霍仁超 宋为群 《中国康复医学杂志》 CAS CSCD 北大核心 2024年第7期940-946,共7页
目的:利用两组加工深度递增式变化的事件相关电位(ERP)Oddball范式探讨经颅直流电刺激(t DCS)响应慢性意识障碍患者的电生理学特征。方法:研究纳入17例无反应觉醒综合征(UWS)和30例微意识状态(MCS)患者,对其进行两组加工深度递增式变化... 目的:利用两组加工深度递增式变化的事件相关电位(ERP)Oddball范式探讨经颅直流电刺激(t DCS)响应慢性意识障碍患者的电生理学特征。方法:研究纳入17例无反应觉醒综合征(UWS)和30例微意识状态(MCS)患者,对其进行两组加工深度递增式变化范式的ERP检查,后在连续10个工作日内接受20次左侧前额叶背外侧(DLPFC)区域t DCS治疗,根据改良昏迷恢复量表(CRS-R)评估结果分为响应者和非响应者,分析干预响应者一般情况特征及电生理学特征。结果:在UWS患者中,性别、年龄、病程、接受手术情况、CRS-R评分、P300出现情况均与t DCS响应性无关(P>0.05);而在MCS患者中,CRS-R评分(P=0.015)和反名-正名(DO)范式中P300出现情况(P=0.005)与tDCS响应性相关,而性别、年龄、病程、接受手术情况、纯音—正名(TO)范式中P300出现情况与响应性无关(P>0.05)。结论:更高的CRS-R评分和分层听觉ERP范式中P300的存在,特别是DO范式中的P300成分与MCS患者的tDCS响应性有关,推测是由于DO范式中P300成分代表患者残存的语义加工处理能力,因此具有优先恢复的能力。 展开更多
关键词 慢性意识障碍 事件相关电位 经颅直流电刺激 P300 改良昏迷恢复量表
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断路器选相投切系统在换流站中的应用研究
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作者 李海涛 董辉波 +3 位作者 邓劲东 程骁 刘东超 须雷 《自动化仪表》 CAS 2024年第9期121-126,共6页
在换流站滤波器组及换流变压器配置断路器选相投切系统,可改善断路器开合暂态过程,在取消合闸电阻工况下仍可避免对电力设备及系统造成冲击。基于多个换流站选相投切工程实施及调试经验,进行了换流站选相投切系统应用的调查。介绍了选... 在换流站滤波器组及换流变压器配置断路器选相投切系统,可改善断路器开合暂态过程,在取消合闸电阻工况下仍可避免对电力设备及系统造成冲击。基于多个换流站选相投切工程实施及调试经验,进行了换流站选相投切系统应用的调查。介绍了选相投切系统构成、选相投切要求、断路器配套及预测试方法等。重点针对滤波器组、换流变压器的选相投切应用,总结了控制策略、选相投切系统带电冲击试验,及工程使用中需重点关注的问题、设备运维要求等,为相关技术人员提供参考。试点工程在特高压断路器中创新性地采用取消合闸电阻、增设选相合闸的专项改造方案。断路器选相投切系统总体运行效果良好,为技术的推广积累了工程运行经验。 展开更多
关键词 换流站 滤波器 换流变压器 高压/特高压直流输电 暂态冲击 选相投切
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不同颅脑部位经颅直流电刺激治疗帕金森病冻结步态的疗效观察
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作者 王聪聪 田小军 +4 位作者 苏洲 郭双喜 杜佳 徐斌 王玉梅 《中国康复》 2024年第7期411-415,共5页
目的:观察经颅直流电刺激(tDCS)治疗帕金森病(PD)冻结步态的临床疗效。方法:选取2023年1月~2023年6月在新乡医学院第一附属医院治疗的PD患者共72例,采用随机数字表法分为对照组、初级运动皮层组(M1组)及左背外侧前额叶皮层组(L-DLPFC组)... 目的:观察经颅直流电刺激(tDCS)治疗帕金森病(PD)冻结步态的临床疗效。方法:选取2023年1月~2023年6月在新乡医学院第一附属医院治疗的PD患者共72例,采用随机数字表法分为对照组、初级运动皮层组(M1组)及左背外侧前额叶皮层组(L-DLPFC组),每组24例。M1组将阳极放置在优势半球M1头皮处,L-DLPFC组将阳极放置在优势半球DLPFC头皮处,阴极均放置在对侧眶上裂,M1组及L-DLPFC组刺激强度为2mA,每次持续时间20min,对照组电极放置位置与M1组相同,仅前1min内给予2mA的刺激。刺激治疗5d。于治疗前及治疗5d后分别采用帕金森病综合评定量表的第3部分(MDS-UPDRSⅢ)、帕金森病冻结步态(FOG)评分、起立行走计时测试(TUGT)对3组患者进行评估。结果:治疗后,M1组、L-DLPFC组MDS-UPDRSⅢ、FOG评分、TUGT时间均较治疗前减少(均P<0.05);M1组、L-DLPFC组MDS-UPDRSⅢ、FOG评分、TUGT时间均较对照组减少(均P<0.05);M1组与L-DLPFC组MDS-UPDRSⅢ、FOG评分、TUGT时间比较差异无统计学意义。结论:在优势半球M1及L-DLPFC应用tDCS可在短时间内改善帕金森病患者的冻结步态症状,提高生活质量。 展开更多
关键词 帕金森病 冻结步态 经颅直流电刺激 初级运动皮层 左背外侧前额叶皮层
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基于聚合型代数多重网格法的三维直流电法自适应有限元正演
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作者 潘克家 王鹏德 +3 位作者 胡双贵 王晋轩 邱乐稳 汤井田 《同济大学学报(自然科学版)》 EI CAS CSCD 北大核心 2024年第11期1794-1802,1812,共10页
在各向异性、起伏地形、真实地质模型电法模拟中,经自适应有限元离散后形成的大型稀疏线性系统存在内存消耗高、求解效率低等缺陷。为此,提出了聚合型代数多重网格(AGMG)法与自适应有限元法的联合算法,在提高正演精度的同时提升计算效率... 在各向异性、起伏地形、真实地质模型电法模拟中,经自适应有限元离散后形成的大型稀疏线性系统存在内存消耗高、求解效率低等缺陷。为此,提出了聚合型代数多重网格(AGMG)法与自适应有限元法的联合算法,在提高正演精度的同时提升计算效率,实现复杂模型三维直流电法大规模正演模拟。对于三维直流电法满足的二阶椭圆边值问题,采用非结构化四面体网格的有限元法离散,并通过自适应策略进行局部加密,再利用AGMG法求解离散形成的大规模稀疏线性方程组。最后,通过复杂地电模型和实际地质模型验证了联合算法的有效性。在千万级自由度的求解中,联合算法比传统迭代法快了20多倍,比代数多重网格法快了近10倍,随着模型复杂度的提高,联合算法的效率优势更加明显。 展开更多
关键词 代数多重网格法 自适应有限元 各向异性 直流电阻率 起伏地形
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不同电学参数和水流条件下电栅对鲤(Cyprinus carpio)的阻拦效果
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作者 石小涛 张政 +6 位作者 黄晓龙 解立辉 李卫东 王渊洋 赵英华 李志敏 白艳勤 《海洋与湖沼》 CAS CSCD 北大核心 2024年第3期546-554,共9页
脉冲直流电导阻鱼技术已被广泛应用于阻止入侵物种扩散、驱赶鱼类远离危险区域并将其引导至有利区域,如鱼道。但是脉冲直流电的有效性受多方面因素的影响,其主导因素目前尚未定论。以鲤为研究对象,在静水条件下采用4因素3水平正交实验... 脉冲直流电导阻鱼技术已被广泛应用于阻止入侵物种扩散、驱赶鱼类远离危险区域并将其引导至有利区域,如鱼道。但是脉冲直流电的有效性受多方面因素的影响,其主导因素目前尚未定论。以鲤为研究对象,在静水条件下采用4因素3水平正交实验方法分析了脉冲电压、脉冲宽度、脉冲频率和电极摆放方式的电栅拦鱼效果及其对鱼类受伤尾数的主次影响,然后选择最优组合开展不同流速下(0,0.3,0.5 m/s)的驱鱼实验,分析流速对拦鱼效果的影响。结果表明:在静水工况下,影响拦鱼电栅效率的主要因素为电极布置方式>脉冲宽度>脉冲频率>脉冲电压,电极布置为方式1(垂直水流间距80 cm)、脉冲电压140 V、脉冲频率10 Hz、脉冲宽度10 ms是拦鱼效果最佳的组合。电学参数对鲤的伤害无显著性,平均受伤尾数不超过实验鱼总数的15%。流水条件下,三种流速工况下拦鱼电栅的阻拦率无显著差异,但是随着流速的增高阻拦率呈现先降低后增加的趋势。该研究将为保护鱼类资源和防止入侵鱼类跨区域传播提供依据。 展开更多
关键词 拦鱼电栅 阻拦效果 脉冲直流电
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