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Coarse-fine joint target parameter estimation method based on AN-RSC in OFDM passive radar

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Journal of Systems Engineering and Electronics 2024年第2期35卷 339-349页

作者： wang Chujun WAN Xianrong yi Jianxin CHENG Feng School of Electronic Information Wuhan UniversityWuhan 430072China

In this paper,we study the accuracy of delay-Doppler parameter estimation of targets in a passive radar using orthogonal frequency division multiplexing(OFDM)signal.A coarse-fine joint estimation method is proposed to achieve better estimation accuracy of target parameters without excessive computational ***,the modulation symbol domain(MSD)method is used to roughly estimate the delay and Doppler of ***,to obtain high-precision Doppler estimation,the atomic norm(AN)based on the multiple measurement vectors(MMV)model(MMV-AN)is used to manifest the signal sparsity in the continuous Doppler *** the same time,a reference signal compensation(RSC)method is presented to obtain highprecision delay *** results based on the OFDM signal show that the coarse-fine joint estimation method based on AN-RSC can obtain a more accurate estimation of target parameters compared with other *** addition,the proposed method also possesses computational advantages compared with the joint parameter estimation.

关键词： passive radar orthogonal frequency division multiplexing(OFDM)signal atomic norm(AN) parameter estimation

Performance of iron-air battery with iron nanoparticle-encapsulated C-N composite electrode

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Frontiers in Energy 2024年第1期18卷 42-53页

作者： Can FANG Xiangmei TANG Jiaoyan wang Qingfeng yi School of Chemistry and Chemical Engineering Hunan University of Science and TechnologyXiangtan 411201China Hunan Provincial Key Laboratory of Advanced Materials for New Energy Storage and Conversion Xiangtan 411201China

Highly efficient and stable iron electrodes are of great significant to the development of iron-air battery(IAB).In this paper,iron nanoparticle-encapsulated C–N composite(NanoFe@CN)was synthesized by pyrolysis using polyaniline as the C–N *** performance of the NanoFe@CN in different electrolytes(alkaline,neutral,and quasi-neutral)was investigated via cyclic voltammetry(CV).The IAB was assembled with NanoFe@CN as the anode and IrO_(2)+Pt/C as the *** effects of different discharging/charging current densities and electrolytes on the battery performance were also *** K_(2)SO_(4)electrolyte can effectively suppress the passivation of iron electrode,and the battery showed a good cycling stability during 180 charging/discharging *** to the pure nano-iron(NanoFe)battery,the NanoFe@CN battery has a more stable cycling stability either in KOH or NH_(4)Cl+KCl electrolyte.

关键词： energy storage and conversion metallic composites nanocomposites iron-air battery iron anode

Influence of in situ formed spinel in bonding phase on mechanical properties and air permeability of magnesia-chrome porous purging materials

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Journal of Iron and Steel Research International 2024年第6期31卷 1459-1472页

作者： yi An Hao Liu Zhou-fu wang Yan Ma Xi-tang wang The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina

Magnesia-chrome porous purging plugs are crucial functional components to remove inclusions and stabilize the flow field during iron and steel ***,practical applications of magnesia-chrome porous purging materials are stil hampered by the poor scouring resistance to molten steel and unstable air permeability owing to their low mechanical properties and uncontrollable pore ***,the particle-packing type magnesiachrome porous purging materials reinforced by in situ formed spinel were prepared using fused magnesia-chrome particles and Al powders as major raw *** results show that in situ formed spinel solid solutions in bonding phase led to the decreased median pore size and increased pore surface fractal dimension from the reactions between Al powders and magnesia-chrome particles and along with high-temperature sintering,bonding between magnesia-chrome particles and the resultant mechanical properties of materials were greatly ***,the results of air permeability tests and polynomial ftting indicated that the formation of spinel solid solutions was the main contributing factor for controllable air permeability,and pressure drop of porous purging materials was positively correlated with surface fractal dimension of ***,the as-prepared porous purging materials added with 6 wt.%Al powders obtained the maximum cold crushing strength(54.2 MPa)and hot modulus of rupture(12.9 MPa)with median pore size of 24.06μm and ftting non-Darcian permeability coefficient of 0.97×10^(-6)m.

关键词： Magnesia Chrome porous purging material Metallic Al-Spinel Mechanical strength Air permeability

Vanadium(V) Complexes Containing Unsymmetrical N-Heterocyclic Carbene Ligands: Highly Efficient Synthesis and Catalytic Behavior towards Ethylene/Propylene Copolymerization

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Chinese Journal of Polymer Science 2024年第1期42卷 32-41,I0006页

作者： yi-Cong wang Hui Zhat Pei-yi Cheng Shu Zhang Xiang-Wei Liu yi-Xian Wu State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical TechnologyBejing 100029China

The highly efficient method has been developed for the synthesis of NHC·VOCl_(3) containing symmetrical or unsymmetrical Nheterocyclic carbene(NHC) ligands by the transmetallation reaction of NHC·AgCl with VOCl_(3).The total isolated yield of VOCl_(3)[1,3-(2,4,6-Me_(3)C_(6)H_(2))_(2)(NCH=)_(2)C:](V4') reached 86% by transmetallation reaction,which is much higher than that(48%) by direct coordination *** methodology has also been used to synthesize the novel vanadium complexes containing unsymmetrical NHC ligands of VOCl_(3)[PhCH_(2)NCH=CHNR)C:](V5',R=2,4,6-Me_(3)C_(6)H_(2);V6',R=2,4-Me_(2)-6-Ph-C_(6)H_(2);V7',R=2,6-^(i)Pr_(2)-C_(6)H_(3)) with high yield,which could not be obtained by direct coordination *** catalytic activity and copolymerization ability would be improved by introducing unsymmetrical NHC ligands due to their less steric bulky *** vanadium complex V5' containing unsymmetrical NHC ligand exhibits higher catalytic activity(3.7×10^(5)g_(copolymer)·mol^(-1) of V·h^(-1)) than that of V4' containing symmetrical NHC ***,the higher propylene incorporation ratio(45.6 mol%) in the copolymers of ethylene with propylene could be obtained by using V5' than that(39.9%) by using V4'.The results would provide a highly efficient strategy for the synthesis of early transition metal complexes containing versitile NHC ligands,affording the catalyst with both high catalytic activity and copolymerization ability for the synthesis of high performance polyolefin elastomers.

关键词： Vanadium complex N-heterocyclic carbene ligand Transmetallation reaction Copolymerization of ethylene with propylene

Single-atom Ag-loaded carbon nitride photocatalysts for efficient degradation of acetaminophen:The role of Ag-atom and O_(2)

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Journal of Environmental Sciences 2024年第5期139卷 12-22页

作者： yi Yuan Wen-Long wang Zhi-Wei wang Jin wang Qian-Yuan Wu Key Laboratory of Microorganism Application and Risk Control of Shenzhen Guangdong Provincial Engineering Research Center for Urban Water Recycling and Environmental SafetyInstitute of Environment and EcologyShenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China Shenzhen Environmental Science and New Energy Technology Engineering Laboratory Tsinghua-Berkeley Shenzhen InstituteShenzhen 518055China College of Materials Science and Engineering Shenzhen UniversityShenzhen 518071China

Carbon nitride has been extensively used as a visible-light photocatalyst,but it has the disadvantages of a low specific surface area,rapid electron-hole recombination,and relatively low light *** this study,single-atom Ag was successfully anchored on ultrathin carbon nitride(UTCN)via thermal polymerization,the catalyst obtained is called *** Ag hardly changed the carbon nitride's layered and porous physical *** exhibited efficient visible-light photocatalytic performances in the degradation of various recalcitrant pollutants,eliminations of 85% were achieved by visible-light irradiation for *** with Ag improved the photocatalytic performance of UTCN by narrowing the forbidden band gap from 2.49 to 2.36 e V and suppressing electron-hole pair *** addition,Ag doping facilitated O_(2) adsorption on UTCN by decreasing the adsorption energy from -0.2 to -2.22 e V and favored the formation of O_(2)^(·-).Electron spin resonance and radical-quenching experiments showed that O_(2)^(·-)was the major reactive species in the degradation of Acetaminophen(paracetamol,APAP).

关键词： Ag single atom Carbon nitride Photocatalysis Visible light Adsorption energy Reactive species

Acyclic Edge Coloring of 1-planar Graphs without 4-cycles

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Acta Mathematicae Applicatae Sinica 2024年第1期40卷 35-44页

作者： Wei-fan wang yi-qiao wang Wan-shun Yang Department of Mathematics Zhejiang Normal UniversityJinhua321004China School of Management Beijing University of Chinese MedicineBeijing100029China School of Mathematics and Information Science Weifang UniversityWeifang261061China

An acyclic edge coloring of a graph G is a proper edge coloring such that there are no bichromatic cycles in *** acyclic chromatic index χ'α(G) of G is the smallest k such that G has an acyclic edge coloring using k *** was conjectured that every simple graph G with maximum degree Δ has χ'_α(G) ≤Δ+2.A1-planar graph is a graph that can be drawn in the plane so that each edge is crossed by at most one other *** this paper,we show that every 1-planar graph G without 4-cycles has χ'_α(G)≤Δ+22.

关键词： 1-planar graph acyclic edge coloring acyclic chromatic index

Effect of mechanical stresses on degradation behavior of high-purity magnesium in bone environments

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Journal of Materials Science & Technology 2024年第4期171卷 252-261页

作者： Yan Yao Jie Xia Lizhen wang Yuanming Gao Xili Ding chao wang Yubo Fan Key Laboratory of Biomechanics and Mechanobiology(Beihang University) Ministry of EducationBeijing Advanced Innovation Center for Biomedical EngineeringSchool of Biological Science and Medical EngineeringSchool of Engineering MedicineBeihang UniversityBeijing 100083China

High-purity(HP)magnesium(Mg)has emerged as a promising biomaterial for supporting functional bone *** previous study found that mechanical stresses and the surrounding fibrotic tissue(subcuta-neous)both play crucial roles in the degradation of HP ***,due to challenges in the degradation and regeneration process in vivo,it remains unclear how stress affects HP Mg degradation in bone en-vironments,limiting its further *** this study,novel loading devices were designed and the effects of tensile and compressive stresses on HP Mg degradation in vivo and in vitro bone environments were quantitatively *** addition,bone osteointegration around HP Mg was explored *** stress increases the degradation rate of HP Mg in vivo and in *** Mg degradation in vivo is more sensitive to stress factors than in vitro,but the sensitivity decreases with corrosion *** volume loss rate of HP Mg is multilinear with the applied stress and degradation *** volume of bone tissue surrounding HP Mg is larger in the no-stress group compared to the stressed groups,which is more pronounced with increasing implantation *** results provide valuable insights for optimiz-ing the design of HP Mg-based implants considering load *** will help to achieve a balance between the degradation rate of the implant and the regeneration rate of the surrounding bone.

关键词： High-purity magnesium Quantitative stresses Degradation Bone environments In vivo and in vitro

Primordial black hole mass functions as a probe of cosmic origin

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Science China(Physics,Mechanics & Astronomy) 2024年第5期67卷 164-171页

作者： yi-Fu Cai Chengfeng Tang Geyu Mo Sheng-Feng Yan chao Chen Xiao-Han Ma Bo wang Wentao Luo Damien A.Easson Antonino Marcianò Deep Space Exploration Laboratory/School of Physical Sciences University of Science and Technology of ChinaHefei 230026China CAS Key Laboratory for Researches in Galaxies and Cosmology/Department of Astronomy School of Astronomy and Space ScienceUniversity of Science and Technology of ChinaHefei 230026China Istituto Nazionale di Fisica Nucleare(INFN) Sezione di MilanoMilano 20146Italy DiSAT Universitàdegli Studi dell'InsubriaComo 22100Italy Jockey Club Institute for Advanced Study The Hong Kong University of Science and TechnologyHong KongChina Department of Physics Arizona State UniversityTempe 85287-1504USA Department of Physics&Center for Field Theory and Particle Physics Fudan UniversityShanghai 200433China Laboratori Nazionali di Frascati INFN Via Enrico Fermi 541 Frascati(Roma)00044Italy INFN sezione Roma Tor Vergata Rome I-00133Italy School of Physics University of Electronic Science and Technology of ChinaChengdu11731China

We discuss a novel window to probe the origin of our universe via the mass functions of primordial black holes(PBHs).The mass functions of PBHs are simply estimated using the conventional Press-Schechter formalism for two paradigms of cosmic origin,including inflationaryΛCDM and bounce *** standard inflationaryΛCDM model cannot generate an appreciable number of massive PBHs;however,non-trivial inflation models with blue-tilted power spectra at small scales and matter bounce cosmology provide formation mechanisms for heavy PBHs,which in turn,may seed the observed supermassive black holes(SMBHs).By fitting the SMBH mass functions at high redshift(z~6)derived from Sloan Digital Sky Survey(SDSS)and Canada-France High-z Quasar Survey(CFHQS)quasars,for two paradigms of cosmic origin,we derive constraints on the PBH density fraction fPBHat z~6 and the characteristic mass M_(★),with the prior assumption that all SMBHs stem from *** demonstrate that this newly proposed procedure,relying on astronomical measurements that utilize deep-field surveys of SMBHs at high redshift,can be used to constrain models of cosmic ***,although not the main focus of this paper,we evolve the mass function from z~6 to z~0 through an assumption of 3×10^(8)-year Eddington’s accretion,and give a rough estimation of fPBHat z~0.

关键词： origin cosmic massive

A promising application of bulk metallic glasses in torque sensor

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Science China(Technological Sciences) 2024年第8期67卷 2505-2514页

作者： LU WenHao MA Jiang wang chao LIU YanHui Institute of Physics Chinese Academy of SciencesBeijing 100190China Shenzhen Key Laboratory of High Performance Nontraditional Manufacturing College of Mechatronics and Control EngineeringShenzhen UniversityShenzhen 518060China

Torque sensors are essential components of robotic joints. In the past, structure optimization of force-sensing elements has been the common approach to improve the performance of the torque sensors. In this work, we demonstrate a torque sensor with bulk metallic glasses as a force-sensing element. Compared with the sensors made of stainless steel and aluminum alloy, the use of bulk metallic glass as a force-sensing element significantly improves sensor sensitivity, linearity, repeatability, hysteresis, and measuring range. Our work not only opens up a new avenue for the application of bulk metallic glasses, but also provides opportunities for enhancing the performance of force/torque sensors through materials optimization.

关键词： bulk metallic glasses amorphous alloys force sensors