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An angular blinking jamming method based on electronically controlled corner reflectors

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Journal of Systems Engineering and Electronics 2024年第2期35卷 330-338页

作者： gan lin WU Zehao WANG Xuesong LI Jianbing State Key Laboratory of Complex Electromagnetic Environmental Effects on Electronics and Information System National University of Defense TechnologyChangsha 410073China

Passive jamming is believed to have very good potential in countermeasure community.In this paper,a passive angular blinking jamming method based on electronically controlled corner reflectors is proposed.The amplitude of the incident wave can be modulated by switching the corner reflector between the penetration state and the reflection state,and the ensemble of multiple corner reflectors with towing rope can result in complex angle decoying effects.Dependency of the decoying effect on corner reflectors’radar cross section and positions are analyzed and simulated.Results show that the angle measured by a monopulse radar can be significantly interfered by this method while the automatic tracking is employed.

关键词： monopulse radar angular blinking jamming corner reflector amplitude-comparison angle measurement metasurface

Engineering nanoporous and solid core-shell architectures of lowplatinum alloy catalysts for high power density PEM fuel cells

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Nano Research 2022年第7期15卷 6148-6155页

作者： Yongqiang Kang Jiaqi Wang Yinping Wei Yongle Wu Dongsheng Xia lin gan Institute of Materials Research Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China

Low-platinum(Pt)alloy catalysts hold promising application in oxygen reduction reaction(ORR)electrocatalysis of protonexchange-membrane fuel cells(PEMFCs).Although significant progress has been made to boost the kinetic ORR mass activity at low current densities in liquid half-cells,little attention was paid to the performance of Pt-based catalysts in realistic PEMFCs particularly at high current densities for high power density,which remains poorly understood.In this paper,we show that,regardless of the kinetic mass activity at the low current density region,the high current density performance of the low-Pt alloy catalysts is dominantly controlled by the total Pt surface area,particularly in low-Pt-loading H_(2)–air PEMFCs.To this end,we propose two different strategies to boost the specific Pt surface area,the post-15-nm dealloyed nanoporous architecture and the sub-5-nm solid core–shell nanoparticles(NPs)through fluidic-bed synthesis,both of which bring in comparably high mass activity and high Pt surface area for large-current-density performance.At medium current density,the dealloyed porous NPs provide substantially higher H_(2)–air PEMFC performance compared to solid core–shell catalysts,despite their similar mass activity in liquid half-cells.Scanning transmission electron microscopy images combined with electron energy loss spectroscopic imaging evidence a previously unreported“semi-immersed nanoporous-Pt/ionomer”structure in contrast to a“fully-immersed core–shellPt/ionomer”structure,thus favoring O_(2) transport and improving the fuel cell performance.Our results provide new insights into the role of Pt nanostructures in concurrently optimizing the mass activity,Pt surface area and Pt/Nafion interface for high power density fuel cells.

关键词： low-platinum alloy catalyst nanoporosity proton-exchange-membrane fuel cells power density triple-phase boundary

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论孔子的天下观

中国哲学史 2024年第1期 5-14页

作者：甘霖四川大学历史文化学院

孔子的天下观包括天人观、自然观、地理观、王霸观和夷夏观,涉及对天人关系、物我关系、区域关系、王霸关系和夷夏关系等基本问题的认识。孔子的这些思想论述,既有继承殷周传统观念的一面,更有从时代出发加以革新和拓展的一面,体现了鲜... 详细信息

孔子的天下观包括天人观、自然观、地理观、王霸观和夷夏观,涉及对天人关系、物我关系、区域关系、王霸关系和夷夏关系等基本问题的认识。孔子的这些思想论述,既有继承殷周传统观念的一面,更有从时代出发加以革新和拓展的一面,体现了鲜明的理性主义精神和博大的人文主义情怀,具有某种“完全开放性”的特点。对于这些思想论述,《论语》的编纂者和历代阐释者,既有合乎客观的认识,也有失于偏颇的理解。今天有必要以新的视野重新审视,并予以新的阐释。

关键词：孔子天下观天人观自然观地理观王霸观夷夏观

Interface engineering of plasmonic induced Fe/N/C-F catalyst with enhanced oxygen catalysis performance for fuel cells application

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Nano Research 2022年第3期15卷 2138-2146页

作者： Xue Yin Ligang Feng Wen Yang Yuanxi Zhang Haiyan Wu Le Yang Lei Zhou lin gan Shaorui Sun Key Laboratory of Cluster Science of Ministry of Education Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion MaterialsSchool of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 100081China School of Chemistry and Chemical Engineering Yangzhou UniversityYangzhou 225002China Institute of Materials Research Shenzhen Geim Graphene CenterTsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China Beijing Key Laboratory for Green Catalysis and Separation College of Environmental and Energy EngineeringBeijing University of TechnologyBeijing 100124China

The low intrinsic activity of Fe/N/C oxygen catalysts restricts their commercial application in the fuel cells technique;herein,we demonstrated the interface engineering of plasmonic induced Fe/N/C-F catalyst with primarily enhanced oxygen reduction performance for fuel cells applications.The strong interaction between F and Fe-N4 active sites modifies the catalyst interfacial properties as revealed by X-ray absorption structure spectrum and density functional theory calculations,which changes the electronic structure of Fe-N active site resulting from more atoms around the active site participating in the reaction as well as super-hydrophobicity from C–F covalent bond.The hybrid contribution from active sites and carbon support is proposed to optimize the three-phase microenvironment efficiently in the catalysis electrode,thereby facilitating efficient oxygen reduction performance.High catalytic performance for oxygen reduction and fuel cells practical application catalyzed by Fe/N/C-F catalyst is thus verified,which offers a novel catalyst system for fuel cells technique.

关键词： interface engineering Fe/N/C catalyst CF_(4)plasma treatment three-phase microenvironment proton exchange membrane fuel cells

Strain-sensitive ferromagnetic two-dimensional Cr_(2)Te_(3)

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Nano Research 2022年第2期15卷 1254-1259页

作者： Junchuan Zhong Mingshan Wang Teng Liu Yinghe Zhao Xiang Xu Shasha Zhou Junbo Han lin gan Tianyou Zhai State Key Laboratory of Materials Processing and Die&Mould Technology and School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China Wuhan National High Magnetic Field Center and Department of Physics Huazhong University of Science and TechnologyWuhan 430074China

Searching for room temperature magnetic two-dimensional(2D)materials is a charming goal,but the number of satisfied materials is tiny.Strain can introduce considerable deformation into the lattice structure of 2D materials,and thus significantly modulate their intrinsic properties.In this work,we demonstrated a remarkable strain-modulated magnetic properties in the chemical vapor deposited Cr_(2)Te_(3) nanoflakes grown on mica substrate.We found the Curie temperature of Cr_(2)Te_(3) nanoflakes can be positively and negatively modulated under tensile and compressive strain respectively,with a maximum varied value of -40 and-90 K,dependent on the thickness of samples.Besides,the coercive field of Cr_(2)Te_(3) nanoflakes also showed a significant decrease under the applied strain,suggesting the decrease of exchange interaction or the change of the magnetization direction.This work suggests a promise to employ interfacial strain to accelerate the practical application of room temperature 2D magnetics.

关键词： 2D magnetic materials strain-sensitive Cr_(2)Te_(3) magnetic properties tuning

低温破碎及装药结构对内弹道性能影响的数值分析

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火炸药学报 2024年第4期47卷 381-392页

作者：林杨淦刘东尧南京理工大学能源与动力工程学院江苏南京210094

以大口径火炮密实装药发射安全性为背景,对火药颗粒低温破碎及装药结构对内弹道特性的影响进行了数学建模和仿真分析。针对中心点传火管结构的大口径火炮密实装药,建立传火管及装药床的双一维两相流数学模型,结合膛内火药颗粒应力及破... 详细信息

以大口径火炮密实装药发射安全性为背景,对火药颗粒低温破碎及装药结构对内弹道特性的影响进行了数学建模和仿真分析。针对中心点传火管结构的大口径火炮密实装药,建立传火管及装药床的双一维两相流数学模型,结合膛内火药颗粒应力及破碎度函数,采用数值差分方法对内弹道过程进行数值仿真,研究火药温度及混合装药方案对火药颗粒破碎度及火炮内弹道性能的影响。结果表明,在低温条件下,单一装药结构火药颗粒将发生破碎,且破碎度随温度降低而增大,在-20℃和-40℃条件下,最大破碎度分别达到1.896和2.487,膛内压力分别为690.32MPa和803.64MPa,增幅达到16.4%;在总装药质量6.25kg不变的条件下,小颗粒药装药质量从0增至0.4kg,最大破碎度从2.487减至1.803,膛内压力从803.64MPa减至740.81MPa,由此可见混合装药结构可以有效避免火药颗粒的破碎。

关键词：物理化学火药破碎低温破碎内弹道发射安全性大口径火炮

Why do platinum catalysts show diverse electrocatalytic performance?

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Fundamental Research 2023年第5期3卷 804-808页

作者： Qiangmin Yu Zhiyuan Zhang Heming Liu Xin Kang Shiyu Ge Shaohai Li lin gan Bilu Liu Shenzhen Geim Graphene Center Tsinghua-Berkeley Shenzhen Institute&Institute of Materials ResearchShenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China

As one of the best electrocatalysts for the hydrogen evolution reaction,platinum catalysts are a benchmark for the performance evaluation of new catalysts.However,platinum catalysts reported in the literature show diverse electrocatalytic performances,resulting in the lack of a common reference standard.In this study,we investigated several factors that affect the performance of platinum catalysts by performing experimental measurements and data processing.These factors included the solution resistance,electrolyte temperature,loading quantity,catalyst microstructure,and normalization method of the current density.Finally,we recommended criteria for the performance evaluation of electrocatalysts.

关键词： Platinum Electrocatalyst Overpotential Solution resistance Loading quantity Microstructure Catalyst area Evaluation criteria

Effect of tungsten oxide on ceria nanorods to support copper species as CO oxidation catalysts

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Journal of Rare Earths 2021年第1期39卷 43-50,I0002页

作者： Yu'nan Li lin gan Rui Si Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials and School of Material Science and EngineeringHubei UniversityWuhan 430062China Zhangjiang Laboratory Shanghai Synchrotron Radiation FacilityShanghai 201204China

In this work,tungsten oxide with different concentrations(0,0.4 at%,2.0 at%and 3.2 at%)was introduced to the ceria nanorods via a deposition-precipitation(DP)approach,and copper species of ca.10 at%were sequentially anchored onto the modified ceria support by a similar DP route.The aim of the study was to investigate the effect of the amount of tungsten oxide(0,0.4 at%,2.0 at%,and 3.2 at%)modifier on the copper-ceria catalysts for CO oxidation reaction and shed light on the structure-activity relationship.By the aids of multiple characterization techniques including N2 adsorption,high-resolution transmission electron microscopy(HRTEM),powder X-ray diffraction(XRD),X-ray absorption fine structure(XAFS),and temperature-programmed reduction by hydrogen(H2-TPR)in combination with the catalytic performance for CO oxidation reaction,it is found that the copper-ceria samples maintain the crystal structure of the fluorite fcc CeO2 phase with the same nanorod-like morphology with the introduction of tungsten oxide,while the textural properties(the surface area,pore volume and pore size)of ceria support and copper-ceria catalysts are changed,and the oxidation states of copper and tungsten are kept the same as Cu2+and W6+before and after the reaction,but the introduction of tungsten oxide(WO3)significantly changes the metal-support interaction(transfer the CuOx clusters to Cu-[Ox]-Ce species),which delivers to impair the catalytic activity of copper-ceria catalysts for CO oxidation reaction.

关键词： Copper catalyst Ceria Tungsten oxide CO oxidation Structure-activity relationship Rare earths

Hierarchically spacing DNA probes on bio-based nanocrystal for spatial detection requirements

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Science Bulletin 2019年第13期64卷 934-940页

作者： lin gan Ya Wang Meng Zhang Xuehuan Xia Jin Huang Key Laboratory of Luminescence and Real-Time Analytical Chemistry Ministry of EducationSchool of Chemistry and Chemical EngineeringSouthwest UniversityChongqing 400715China Chongqing Key Laboratory of Soft-Matter Material Chemistry and Function Manufacturing Southwest UniversityChongqing 400715China

Sterically spacing and locating functional matters at the nanoscale exert critical effects on their application,especially for the fluorescence probes whose aggregation causes emission quenching.Here we achieved a hierarchical spacing strategy of DNA fluorescence probes for ion detection via locating them separately on rod-like cellulose nanocrystals(CNCs)and further isolating CNCs by pre-grafting long molecular chains.Controlling chemical structure of CNC and location degree could adjust the interspace of DNA probes(with a molecular length of ca.3.6 nm)in a range of 3.5-6.5 nm with a gradient about 0.2 nm.A length up to micrometer scale of the CNC nanorods was necessary to provide DNA probes with well-separated grafting locations and enough freedom,which brought a vast linear detection range from 10 nmol/L to 5 μmol/L of Hg^2+ concentration.The abundant reactive sites on CNC allowed a grafting pre-location of poly(tert-butyl acrylate)(PtBA)to promote the isolation of DNA probes.Controlled radical polymerization was employed to adj ust the length of PtBA molecular chains,which increased the linear sensitivity coefficient of Hg^2+ detection by ca.2.5 times.This hierarchical nanoscale spacing concept based on chemical design can hopefully cond uce to the development of biosensor and medical diagnosis.A hierarchical spacing strategy was applied to separate DNA fluorescent probes on CNCs and detect ion concentration linearly.The first-level spacing was to locate probes uniformly on CNCs,obtaining a wide linear range;and the second-level spacing was to isolate CNCs with polymer,obtaining an increased linear coefficient.

关键词： Cellulose nanocrystal DNA fluorescence probe Steric spacing Surface modification Mercury ion detection