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翻瓣导萌术联合口腔正畸治疗儿童及青少年上颌埋伏阻生前牙的临床疗效

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中外医疗 2024年第16期43卷 21-24页

作者：邹静田云峰武威市凉州医院口腔科甘肃武威733000

目的分析儿童及青少年上颌埋伏阻生前牙患儿接受翻瓣导萌术联合口腔正畸的治疗效果。方法方便选取2018年9月—2022年12月武威市凉州医院接受治疗的73例上颌埋伏阻生前牙患儿为研究对象,应用摸球法分为对照组(35例)与观察组(38例)。对照... 详细信息

目的分析儿童及青少年上颌埋伏阻生前牙患儿接受翻瓣导萌术联合口腔正畸的治疗效果。方法方便选取2018年9月—2022年12月武威市凉州医院接受治疗的73例上颌埋伏阻生前牙患儿为研究对象,应用摸球法分为对照组(35例)与观察组(38例)。对照组实施单一翻瓣导萌术治疗,观察组实施翻瓣导萌术联合口腔正畸治疗,对比两组手术成功率、上颌埋伏阻生前牙萌出时间、并发症发生率及治疗前后患儿的语言、咀嚼功能、美观度。结果观察组患儿的手术成功率为97.37%,高于对照组82.86%,差异有统计学意义(χ^(2)=4.425,P0.05)。结论儿童及青少年上颌埋伏阻生前牙患儿在翻瓣导萌术治疗的同时接受口腔正畸治疗,能够较大程度提高手术成功率,缩短患儿的上颌埋伏阻生前牙萌出时间,降低并发症发生率。同时改善患儿牙齿美观度。

关键词：上颌埋伏阻生前牙翻瓣导萌术口腔正畸手术成功率牙齿美观度

Pd-La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)composite as active and stable oxygen electrode for reversible solid oxide cells

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Journal of Rare Earths 2023年第4期41卷 599-604页

作者： Rui Yang yunfeng tian Yun Liu Jian Pu Bo Chi Center for Fuel Cell Innovation State Key Laboratory of Material Processing and Die&Mould TechnologyHuazhong University of Science and TechnologyWuhan 430074China Jiangsu Key Laboratory of Coal-based Greenhouse Gas Control and Utilization School of Materials Science and PhysicsChina University of Mining and TechnologyXuzhou 221116China

To promote the electrocatalytic activity and stability of traditional(a_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)(LSCF)oxygen electrodes in reversible solid oxide cells(RSOCs),conventional physical mixed method was used to prepare the Pd-LSCF composite oxygen *** cell with Pd-LSCF|GDC|YSZ|Ni-YSZ configuration shows perfect electrochemical performance in both solid oxide fuel cell(SOFC)mode and solid oxide electrolysis cell(SOEC)*** the SOFC mode,the cell achieves a power density of 1.73 W/cm^(2)at800℃higher than that of the LSCF oxygen electrode with 1.38 W/cm^(2).In the SOEC mode,the current density at 1.5 V is 1.67 A/cm^(2)at 800℃under 50 vol%steam ***,the reversibility and stability of the RSOCs were tested during 192 h long-term reversible *** degradation rate of the cell is only 2.2%/100 h and 2.5%/100 h in the SOEC and the SOFC modes,*** results confirm that compositing Pd with the LSCF oxygen electrode can considerably boost the electrochemical performance of LSCF electrode in RSOCs field.

关键词： Reversible solid oxide cells Composite Oxygen electrode La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) Electrochemical performance Rare earths

Influence of Virtual Synchronous Generators on Low Frequency Oscillations

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CSEE Journal of Power and Energy Systems 2022年第4期8卷 1029-1038页

作者： Hui Liu Dawei Sun Feng Zhao yunfeng tian Peng Song Xuekun Cheng State Grid Wind-Photovoltaic-Energy Storage Hybrid Power Generation Technology Laboratory and State Grid Jibei Electric Power Research Institute(North China Electric Power Research Insititute Co.Ltd) Beijing 100045China State Grid Xinyuan Zhangjiakou Wind PhotovoltaicStorage and Transmission Pilot Power Station Co.LtdZhangjiakou 075000China

By simulating the operating dynamics of synchronous generators(SGs),the use of virtual synchronous gen-rators(VSGs)can help overcome inverter-based generators'shortcomings of low inertia and minimal damping for gridforming ***'stability are very important for their solar and wind electricity ***,the related research primarily focuses on VSGs and their applications for *** has been little research to explore how VSGs effect low frequency oscillations in power transmission *** paper describes a small-signal model of a VSGSG interconnected system,which is suitable for studying low frequency oscillation damping in a power transmission *** on this model,the effects of VSGs on low frequency oscillations are compared with the effects of SGs to reveal the mechanism of how VSGs infuence damping *** influence of each VSG control loop on oscillations is also analyzed in this ***,the low frequency oscillation risks with different types of VSGs are ***,experiments on a real-time laboratory(RT-LAB)platform are conducted to verify the small-signal analysis results.

关键词： Grid-forming inverters low frequency oscillation participation factor renewable electricity small-signal model virtual synchronous generator(VSG)

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长尾管固体火箭发动机内部流动特性仿真分析

弹箭与制导学报 2024年第4期44卷 46-52页

作者：毛纪银杜勇田云峰高宏伟李金福山东特种工业集团有限公司山东淄博255201 中国兵器工业导航与控制技术研究所北京100089

为分析长尾管固体火箭发动机的内部流动特性,编制微分内弹道程序进行发动机内弹道解算;同时采用自定义函数建立质量进口条件、动网格技术模拟燃面推移、欧拉-拉格朗日模型结合粒子随机游走模型,对无长尾与有长尾结构固体火箭发动机三维... 详细信息

为分析长尾管固体火箭发动机的内部流动特性,编制微分内弹道程序进行发动机内弹道解算;同时采用自定义函数建立质量进口条件、动网格技术模拟燃面推移、欧拉-拉格朗日模型结合粒子随机游走模型,对无长尾与有长尾结构固体火箭发动机三维两相瞬态内流场展开对比研究,对比了发动机的性能,分析了长尾结构对气相流动特性与不同直径颗粒的运动分布的影响。分析结果表明:内弹道与流场仿真的发动机平衡压力基本一致。有长尾结构带来了沿程阻力损失,内部平衡压强要高于无长尾结构发动机压力,导致了装药燃烧加快,输出推力反而减小;燃气流经长尾区域流速增加明显,但粒子作用会导致轴线附近流速与温度的震荡,温度整体变化小,故此区域热防护应该重点考虑;由于惯性,粒子在长尾区域先汇集后发散,随粒径增加,粒子汇集区越靠前,散布程度越大,气流对粒子运动作用越小。

关键词：长尾管固体火箭发动机内弹道两相流装药燃烧流动特性

High performance and stability of double perovskite-type oxide NdBa0.5Ca0.5Co1.5Fe0.5O5+δas an oxygen electrode for reversible solid oxide electrochemical cell

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Journal of Energy Chemistry 2020年第4期29卷 108-115页

作者： yunfeng tian Yun Liu Wenjie Wang Lichao Jia Jian Pu Bo Chi Jian Li Center for Fuel Cell Innovation State Key Laboratory of Material Processing and Die&Mould TechnologySchool of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074HubeiChina China-EU Institute for Clean and Renewable Energy Huazhong University of Science and TechnologyWuhan 430074HubeiChina

In this study,we successfully synthesized double perovskite-type oxide NdBa0.5Ca0.5Co1.5Fe0.5O5+δ(NBCCF)using a conventional wet chemical method as the oxygen electrode for reversible solid oxide electrochemical cells(RSOCs).The polarization resistance(Rp)of the composite electrode NBCCFGd0.1Ce0.9O2(GDC)is only 0.079Ωcm^2 at 800℃under *** single cell based on NBCCF-GDC electrode displays a peak power density of 0.941 W/cm^2 in fuel cell mode and a low Rp value of 0.134Ωcm^*** electrolysis cell mode,the cell displays an outstanding oxygen evolution reaction(OER)activity and shows current density as high as 0.92 A/cm^2 with 50 vol%AH(Absolute Humidity)at 800℃and applied voltage of 1.3 *** importantly,the cell exhibits admirable durability of 60 h both in electrolysis mode and fuel cell mode with distinguished *** these results suggest that NBCCF is a promising candidate electrode for RSOC.

关键词： Reversible solid oxide electrochemical cell Double perovsldte Composite electrode Stability Reversibility

非次正规的偶数阶非幂零真子群的个数不超过21的非可解群

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烟台大学学报（自然科学与工程版） 2024年第2期37卷 125-127页

作者：田云凤史江涛刘文静烟台大学数学与信息科学学院山东烟台264005

为了进一步研究特殊子群的数量性质对有限群可解性的影响,证明了非次正规的偶数阶非幂零真子群的个数不超过21的非可解群仅有交错群A_(5)和特殊线性群SL_(2)(5)。

关键词：偶数阶非幂零真子群可解群非可解群

Measurement of subsidence in the Yangbajing geothermal fields,Tibet,from TerraSAR-X InSAR time series analysis

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International Journal of Digital Earth 2016年第7期9卷 697-709页

作者： Yongsheng Li Jingfa Zhang Zhenhong Li Yi Luo Wenliang Jianga yunfeng tian Key Laboratory of Crustal Dynamics Institute of Crustal DynamicsChina Earthquake AdministrationBeijingPeople’s Republic of China School of Civil Engineering and Geosciences Newcastle UniversityNewcastle upon TyneUK

Yangbajain contains the largest geothermal energy power station in *** explorations in Yangbajain first started in 1976,and two plants were subsequently built in 1981 and 1986.A large amount of geothermal fluids have been extracted since then,leading to considerable surface subsidence around the geothermal *** this paper,InSAR time series analysis is applied to map the subsidence of the Yangbajain geothermal fields during the period from December 2011 to November 2012 using 16 senses of TerraSAR-X stripmap SAR *** the case of the TerraSAR-X data,most orbital fringes were removed using precise orbits during the interferometric ***,residual orbital ramps remain in some interferograms due to the uncertainties in the TerraSAR-X *** remove the residual orbital ramps,we estimated a best-fit‘twisted plane’for each epoch interferogram using quadratic polynomial models based on a network *** method removes most of the long-wavelength signals,including orbit ramps and atmospheric *** vertically stratified component(Topography Correlated Atmospheric Delay,TCAD)was also removed using a network *** the influence of seasonal frozen ground(SFG)is not taken into consideration,our results show that the subsidence rate around power plant I(the south plant)is approximately 20 mm/yr with a peak of 30 mm/*** subsidence rate around power plant II(the north plant)is approximately 10 mm/yr,when accounting for the influence of SFG on the power plant and its surrounding ground *** results show that ground motion is caused by seasonal frozen ground and is strongly related to the temperature change.

关键词： Yangbajain geothermal surface subsidence small baseline subset InSAR time series seasonal frozen ground

New two-layer Ruddlesden-Popper cathode materials for protonic ceramics fuel cells

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Journal of Advanced Ceramics 2021年第5期10卷 1052-1060页

作者： Yihan LING tianming GUO Yangyang GUO Yang YANG yunfeng tian Xinxin WANG Xuemei OU Peizhong FENG School of Materials Science and Physics China University of Mining and TechnologyXuzhou 221116China

New two-layer Ruddlesden-Popper(RP)oxide La_(0.25)Sr_(2.75)FeNiO_(7-δ)(LSFN)in the combination of Sr_(3)Fe_(2)O_(7-δ) and La_(3)Ni_(2)O_(7-δ) was successfully synthesized and studied as the potential active single-phase and composite cathode for protonic ceramics fuel cells(PCFCs).LSFN with the tetragonal symmetrical structure(IMmmm)is confinned,and the co-existence of Fe^(3+)/Fe^(4+) and Ni^(3+)/Ni^(2+) couples is demonstrated by X-ray photoelectron spectrometer(XPS)*** LSFN conductivity is apparently enhanced after Ni doping in Fe-site,and nearly three times those of Sr_(3)Fe_(2)O_(7-δ),which is directly related to the carrier concentration and conductor ***,anode supported PCFCs using LSFN-BaZr_(0.1)Ce_(0.7)Y_(0.2)O_(3-δ)(LSFN-BZCY)composite cathode achieved high power density(426 mW·cm^(-2) at 650℃)and low electrode interface polarization resistance(0.26Ω·cm^(2)).Besides,distribution of relaxation time(DRT)function technology was further used to analyse the electrode polarization *** observed three peaks(Pl,P2,and P3)separated by DRT shifted to the high frequency region with the decreasing temperature,suggesting that the charge transfer at the electrode-electrolyte interfaces becomes more difficult at reduced *** results demonstrate that new two-layer RP phase LSFN can be a promising cathode candidate for PCFCs.

关键词： protonic ceramics fuel cells(PCFCs) Ruddlesden-Popper(RP)phase single-phase cathode distribution of relaxation time(DRT)function charge transfer

2023年积石山6.2级地震诱发的中川乡泥石流灾害过程与成因分析

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地震工程学报 2024年第4期46卷 802-817页

作者：罗毅李德文姜文亮李林林焦其松田云锋李强李永生应急管理部国家自然灾害防治研究院北京100085 应急卫星工程与应用应急管理部重点实验室北京100085 复合链生自然灾害动力学应急管理部重点实验室北京100085

强震极易诱发山区灾变性的泥石流过程,但需辅以必要的地貌、地质、水文或气候条件。2023年积石山地震诱发的青海省民和县中川乡泥石流,因其导致大量人员伤亡而备受关注。基于对中川乡泥石流沟谷及其周边区域的综合考察,包括地貌与第四... 详细信息

强震极易诱发山区灾变性的泥石流过程,但需辅以必要的地貌、地质、水文或气候条件。2023年积石山地震诱发的青海省民和县中川乡泥石流,因其导致大量人员伤亡而备受关注。基于对中川乡泥石流沟谷及其周边区域的综合考察,包括地貌与第四纪地质特征、天然剖面、泥石流物源和堆积物的颗粒度、颗粒形状特征,以及灾前卫星影像和灾后多型号无人机航摄的多尺度地貌形态等,文章对灾害过程特征、影响因素以及未来防控进行初步的分析和讨论。泥石流在沟谷处的侵蚀程度、堆积厚度及空间分布等特征表明,物源区主要集中在草滩村上游右岸支沟源头。物源区地层丰富的细砂和传统提灌耕作方式,为强震动下滑塌触发提供了有利条件。现场调查表明,物源主要通过群发式浅层(2~3 m)滑塌进行补给,并在运移过程中不断破碎和分散;浅部稳定隔水层的存在和泉水的出露,为源区物质提供持续的水源补给,最终形成流动性的泥石流。灾前流通区谷地横、纵剖面复杂,局部存在小水塘和沟道阻塞的情况,增加了泥石流的阵发性和破坏能力。现场残余堆积物和淤泥痕迹的空间分布特征表明,本次泥石流具有典型的栓流式特征,表现出黏度极大的特点。拥堵导致泥石流淤高和规模持续扩大,持续增加的势能最终导致泥石流冲破谷地障碍继续流动,沿途侵蚀和堆积时有发生。堆积区地形的进一步展开,导致泥石流更容易发生分散和堆积,因此,位于堆积区谷地内的民宅受灾最为严重。此外,由于寒冷天气和夜半发震,以及群众对灾害性质缺乏认知等原因,也在一定程度上加剧了本次泥石流灾害的严重程度。鉴于黄河上游地质构造环境类似于官亭盆地的中小盆地众多,人居环境及人地关系也都相近,可结合本次灾害特点,有步骤地开展灾害调查和排查工作。在此基础上,针对已识别的高风险隐患点,定期开展巡查排查,加强重大灾害风险的预测和预警。同时,加强宣传和科普,提升公众对地震及链生灾害的科学认知水平。

关键词：积石山地震地震滑塌泥石流高分7号官亭盆地