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Ligand effect in surface atomic sites of group VI B transition metals on ultrathin Pt nanowires for enhanced oxygen reduction

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Nano Research 2024年第6期17卷 5298-5304页

作者： Yuwei He Yueguang Chen Renjie Wu zhihe xiao Mengxian Li Chunfeng Shi Leyu Wang State Key Laboratory of Chemical Resource Engineering College of ChemistryBeijing University of Chemical TechnologyBeijing 100029China State Key Laboratory of Petroleum Molecular and Process Engineering SINOPEC Research Institute of Petroleum Processing Co.Beijing 100083China

Increasing the utilization efficiency of platinum is critical for advancing proton exchange-membrane fuel cells(PEMFCs).Despite extensive research on catalysts for the cathodic oxygen reduction reaction(ORR),developing highly active and durable Pt-based catalysts that can suppress surface dealloying in corrosive acid conditions remains ***,we report a facile synthesis of bimetallic ultrathin PtM(M=Mo,W,and Cr)nanowires(NWs)composed of group VI B transition metal atomic sites anchored on the *** NWs possess uniform sizes and well-controlled atomic *** to PtW and PtCr catalysts,the PtMo0.05 NWs exhibit the highest half-wave potential of 0.935 V and a mass activity of 1.43 A·mgPt^(−1).Remarkably,they demonstrate a remarkable 23.8-fold enhancement in mass activity compared to commercial Pt/C for ORR,surpassing previously reported Pt-based ***,the PtMo NWs cathode in membrane electrode assembly tests achieves a remarkable peak power density of 1.443 W·cm^(−2)(H_(2)-O_(2)conditions at 80℃),which is 1.09 times that of commercial Pt/*** ligand effect in the bimetallic surface not only facilitates strong coupling between Mo(4d)and Pt(5d)atomic orbitals to hinder atom leaching but also modulates the d-states of active site,significantly optimizing the adsorption of key oxygen(*O and*OH)species and accelerating the rate-determining step in ORR pathways.

关键词： ligand effect oxygen reduction reaction group VI B transition metal ultrathin nanowires multiple oxygen species

Synthesis of Load Impedances That Reduce TE-Scattering from Conducting Cylinder with Arbitrary Cross Section

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Journal of Systems Engineering and Electronics 1997年第4期8卷 40-49页

作者： Yin, Hongcheng Huang, Chen xiao, zhihe Air Force Radar Research Inst Beijing China

The reduction of TE-scattering by a conducting cylinder with multiple surface impedance loads is investigated. Synthesis procedures are developed to find the optimal loading which result in zero scattering in the desired directions or at several frequencies. Numerical results of these procedures are presented. The theoretical predictions are confirmed with an experiment. The proposed synthesis procedure is completely general and can be applied to arbitrarily shaped conducting bodies.

关键词： Electromagnetic scattering Impedance loading Impedance synthesis Radar cross section.

Semi-analytical Solutions for Wellbores with Graded Skin Zones in Poroelastic Media

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Acta Mechanica Solida Sinica 2024年第3期37卷 385-395页

作者： Zhiqiang Fan zhihe Jin School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an710072China Department of Mechanical Engineering University of MaineOronoME04469USA

In analyzing the complex interaction between the wellbore and the reservoir formation,the hydromechanical properties of the region proximal to the wellbore,referred to as the“wellbore skin zone”,play a pivotal role in determining flow dynamics and the resulting formation *** models of the wellbore skin zone generally assume a constant permeability throughout,resulting in a sharp permeability discontinuity at the skin-reservoir *** paper introduces a model for a wellbore with a continuously graded skin zone of finite thickness within a poroelastic *** solutions are derived using the Laplace transform method,addressing both positive and negative skin *** results are presented to illustrate the effects of graded permeability/skin zone thickness on pore pressures and stresses around a *** results highlight a distinct divergence in stress and pore pressure fields when comparing wellbores with negative skin zones to those with positive skin zones or no skin at all.

关键词： Poroelastic Graded permeability Analytical solution Wellbore Skin zone

Effects of dynamical spanwise retraction and stretch on flapping-wing forward flights

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Chinese Journal of Aeronautics 2024年第4期37卷 181-202页

作者： Kang LIU Bifeng SONG Ang CHEN zhihe WANG Dong XUE Wenqing YANG School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Intelligent Aircraft Research Center Chengdu Technological UniversityChengdu 610031China Research&Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518057China Harbin Institute of Technology Shenzhen 518055China

Birds and bats retract and stretch their wings dynamically during each flap in level flights, implying intriguing mechanisms for the aerodynamic performance improvement of flapping wings. A numerical investigation into the aerodynamic effects of such bio-inspired concept in forward flights has been performed based on a three-dimensional wing in plunging motion and a twosection wing in flapping motion. The currently considered Reynolds number and Strouhal number are Re=1.5×10^(5) and St=0.3, respectively. During the research, the mean angle of attack is varied in relatively wide ranges to achieve lift-thrust interconversion for the wings. The conclusive results show that dynamical spanwise retraction and stretch has induced three absolutely desirable scenarios for the oscillating wings in forward flights, namely producing more lift and consuming less power for a given thrust generation, producing more thrust and consuming less power for a given lift generation, and producing more lift and more thrust while consuming less power. Furthermore,the morphing wings have alleviated periodical aerodynamic load fluctuations compared with the non-morphing baseline. The mechanism of the aerodynamic effects of the bionic morphing mode is analyzed with the aid of field visualization. The current article is the first to reveal the absolute advantages of the bionic spanwise morphing. Hopefully, it may help comprehend the behaviors of natural fliers and provide inspirations for performance enhancement of micro artificial flappingwing vehicles.

关键词： Flapping wing Morphing wing Bionic Aerodynamics Vortex Flight

CATE240C型挖掘机动臂举升缓慢的原因分析和排查方法

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工程机械 2005年第8期36卷 61-62页

作者：肖智和广东省水利水电第三工程局

一台CAT E240C型挖掘机在装车时动臂举升缓慢,其它工作正常;当只做动臂举升时,速度稍微快一点.

关键词：挖掘机动臂举升工作原理动臂优先水利机械举升速度

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基于散射分布函数模型的近远场变换技术研究

电波科学学报 2015年第2期30卷 371-377页

作者：高超袁晓峰肖志河白杨中国传媒大学信息工程学院北京100024 电磁散射重点实验室北京100854

全尺寸目标的电磁散射特性测试,需要足够大的测试距离或紧缩场系统,但是建设满足远场条件的室外静态场与室内紧缩场需要巨大的经费投入和很高的技术条件,更无法对飞行器进行现场成像与雷达散射截面(Radar Cross Section,RCS)诊断.针对... 详细信息

全尺寸目标的电磁散射特性测试,需要足够大的测试距离或紧缩场系统,但是建设满足远场条件的室外静态场与室内紧缩场需要巨大的经费投入和很高的技术条件,更无法对飞行器进行现场成像与雷达散射截面(Radar Cross Section,RCS)诊断.针对近距离测试检定飞行器隐身性能的需求,提出了基于散射分布函数模型的近远场变换算法.建立三维散射分布函数模型,采用三维扫描方式记录近场数据,将球面波函数分别在柱坐标系、三维直角坐标系与球坐标系下展开,变换得到目标的远场数据,通过三维逆傅里叶变换与插值算法给出目标的三维重建图像与远场RCS.仿真分析与实验表明,算法准确有效.

关键词：电磁散射测量散射分布函数近场远场变换

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从市场化改革看中国的可持续发展

理论前沿 2008年第14期527卷 19-22页

作者：肖治合蔡志洲北京大学经济学院中国国民经济核算与经济增长研究中心

改革开放30年以来,市场化改革使中国成功地由计划经济转轨为市场经济,并在渐进的改革中逐渐释放经济活动中的潜能,使中国取得持续稳定的高速经济增长。本文回顾了中国市场化改革的基本进程和主要特征,指出现阶段中国的要素市场化改革仍... 详细信息

改革开放30年以来,市场化改革使中国成功地由计划经济转轨为市场经济,并在渐进的改革中逐渐释放经济活动中的潜能,使中国取得持续稳定的高速经济增长。本文回顾了中国市场化改革的基本进程和主要特征,指出现阶段中国的要素市场化改革仍然滞后于商品市场化改革。当前中国经济正处于一个重要的发展时期,随着经济规模的不断扩大,可持续发展已经越来越成为我们应该关注的重要课题。本文指出,要保持可持续发展,政府的宏观调控是非常重要的,但不能忽视市场本身的制度建设,中国应该继续深化商品市场化和要素市场化的进程。

关键词：市场化改革通货膨胀生产要素市场可持续发展

On　the　Derivation　of　Angular　Glint　from　Backscattering　Measurements　of　Echo　Relative　Phase

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Journal of Systems Engineering and Electronics 1996年第3期7卷 1-7页

作者： Yin Hongcheng Huang Peikang xiao zhihe (Air Force Radar Research Institute, P.O.Box 2862, Beijing 100085, China Electromagnetic Scattering Laboratory China National Space Administration P.O.Box 142-207, Beijing 100854, China) Air Force Radar Research Institute P.O. Box 2862 Beijing 100085 China Electromagnetic Scattering Laboratory China National Space Administration P.O. Box 142-207 Beijing 100854 China

From the backscattering measurements of a two-point target consisting of two spheres,we discovered that the backward angular glint can be obtained by evaluating the derivative of the measured data of backscattering echo relative phase versus incident angles. A representative vector model of N-point target consisting of N anisotropic point scatterers has been proposed to reveal the inherent law implied by the experimental phenomenon. Analytical arguments then demonstrate that, under certain conditions the equivalence can be found between the backward angular glint and the derivative of backscattering echo relative phase with respect to incident angles. This work is of particular value in deriving angular glint from backscattering measurement in the case of no bistatic scattering measurement capability.

关键词： Echo phase Augular glint Radar target Electromagenetic scattering.

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飞行器雷达隐身测试评估技术及发展

北京航空航天大学学报 2015年第10期41卷 1873-1879页

作者：肖志河高超白杨袁晓峰电磁散射重点实验室北京100854 中国传媒大学信息工程学院北京100024

武器装备全面隐身化,隐身性能指标成为装备最重要的战技指标之一.隐身测试评估是实现装备隐身性能的关键指标和不可缺少的重要环节,涉及隐身装备从方案设计验证、研制方案筛选、部件和整机隐身效果评估、使用维护检定等全生命周期.综述... 详细信息

武器装备全面隐身化,隐身性能指标成为装备最重要的战技指标之一.隐身测试评估是实现装备隐身性能的关键指标和不可缺少的重要环节,涉及隐身装备从方案设计验证、研制方案筛选、部件和整机隐身效果评估、使用维护检定等全生命周期.综述了飞行器雷达隐身性能试验测试体系和测试评估方法,介绍了国内外典型的测试场及测量技术进展,详细分析了低散射诊断实验测试技术的最新成果,展望了飞行器隐身电磁特性测试技术未来发展趋势.

关键词：雷达散射截面隐身飞行器测试评估低散射测量雷达成像