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On n-universal quadratic forms over dyadic local fields

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Science China Mathematics 2024年第7期67卷 1481-1506页

作者： Zilong he Yong Hu School of Computer Science and Technology Dongguan University of TechnologyDongguan523808China Department of Mathematics Southern University of Science and TechnologyShenzhen518055China

Let n≥2 be an integer. We give necessary and sufficient conditions for an integral quadratic form over dyadic local fields to be n-universal by using invariants from Beli's theory of bases of norm ***, we provide a minimal set for testing n-universal quadratic forms over dyadic local fields, as an analogue of Bhargava and Hanke's 290-theorem(or Conway and Schneeberger's 15-theorem) on universal quadratic forms with integer coefficients.

关键词： integral quadratic forms n-universal quadratic forms dyadic fields 290-theorem

维普期刊数据库

Low profile cavity-embedded ultra-wideband UHF array antenna with end-fire beams

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Journal of Electronic Science and Technology 2024年第2期22卷 24-35页

作者： Huan he Wen-Song Wang Southwest China Institute of Electronic Technology Chengdu610036China School of Electrical and Electronic Engineering Department Nanyang Technological UniversitySingapore639798Singapore

A low-profile,vertically polarized,ultra-wideband array antenna with end-fire beams operating in an ultra-high frequency(UHF)band is developed in this *** array antenna consists of 1×16 log-periodic top-hat loaded monopole antenna arrays and is feasible to embed into a shallow cavity to further reduce the array *** is introduced in the proposed antenna element to reduce profile height and the rectangular top hats are carefully designed to minimize the transverse *** results show that when the antenna array operates in a frequency range of 300 MHz-900 MHz,the end-fire radiation pattern achieves±45°scanning range in the horizontal *** prototypes of the proposed end-fire antenna element and a uniformly spaced linear array(1×2)are fabricated and *** end-fire antenna array should be suitable for airborne applications where low-profile and conformal scanning phased antenna arrays with end-fire radiations are *** design is attractive for airborne platform applications that are used to search,discover,identify,and scout the aerial target with vertically polarized beams.

关键词： End-fire radiation Low-profile Vertical polarization Log-periodic array

Cooperative composites anchored with single atom Pb and carbon confined PbO nanoparticles for superior lead-carbon batteries

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Journal of Energy Chemistry 2024年第10期97卷 486-497页

作者： Puqiang he Yi Yang Hui Huang Jing Huang Hongbiao Wang Yapeng he Zhongcheng Guo Faculty of Metallurgical and Energy Engineering Kunming University of Science and Technology Metallurgical Electrode Material Engineering Technology Research Center of Yunnan Province Kunming hendera Technology Co.LTD.

The mitigation of sulphation and parasitic hydrogen evolution is considered as prominent research emphasis for the development of lead-carbon batteries（LCBs） in large-scale energy storage ***,cooperative Pb-C composites consisting of single atom Pb and carbon-encapsulated PbO nanoparticles were prepared by freeze-drying technique and pyrolytic reduction to address above *** innovative use of Pb2+to cross-link sodium alginate enabled a uniform distribution of Pb in the composites,generating Pb-C-PbO three-phase *** analysis and theoretical calculations revealed the synergistic interactions between single-atom Pb and PbO nanoparticles in suppressing parasitic hydrogen evolution and promoting the adsorption of Pb *** presence of monatomic Pb and PbO enhanced the affinity of the composites for the negative active materials and facilitated the transformation of the active materials from bulk into spherical shapes to enhance the specific surface area,thereby counteracting *** the coordinated integration of various functionalities offered by Pb@C-x,the cycle life of the battery at HRPSoC reaches 7025 cycles,which is two times for LCB with pure carbon ***,the discharge capacity increased from 3.52 to 3.79 *** study provides substantial insights into the construction of Pb-C composites for LCBs to inhibit negative sulphation and hydrogen evolution.

关键词： Hydrogen evolution Lead carbon composites Lead-carbon battery Negative sulphation Single-atom

The chlorine evolution reaction promoted by organocatalysts with amide functional groups

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Science China Chemistry 2024年第3期67卷 749-750页

作者： Lan Zhao Liang-Nian he State Key Laboratory and Institute of Elemento-Organic Chemistry College of ChemistryNankai UniversityTianjin 300071China

Since the nineteenth century, the chlor-alkali process entails the electrochemical oxidation of sodium chloride solutions to Cl_(2) by the chlorine evolution reaction(CER) and the simultaneous production of sodium hyd... 详细信息

关键词： chlorine hydroxide promoted

维普期刊数据库

Scalable graphene foam with ultrahigh conductivity for stabilizing Pt towards efficient hydrogen evolution

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Nano Research 2024年第8期17卷 6968-6976页

作者： Ming Zhao Meng Huang Huihui Jin Dayin he Wei Qian Zixin Zhang Daping he State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China Hubei Engineering Research Center of RF-Microwave Technology and Application Wuhan University of TechnologyWuhan 430070China School of Information Engineering Wuhan University of TechnologyWuhan 430070China School of Chemistry and Materials Science University of Science and Technology of ChinaHefei 230026China Sanya Science and Education Innovation Park of Wuhan University of Technology Sanya 572000China

For the carbon-based catalyst to be active and stable,especially in harsh electrochemical environments,the key is to decrease the concentration of defects and raise the degree of graphitization of the carbon ***,we develop a highly graphitized graphene foam with multiplicated structure to fabricate self-supporting Pt-based catalysts for efficient and stable hydrogen evolution reaction(heR)*** foam(GO-2850)is obtained through an ultra-high temperature treatment at 2850℃,with perfect graphene structure and extremely low defect,ensuring high electrical conductivity and corrosion ***,its multiplicated structure provides an inherently favorable environment for the dispersion of Pt nanoparticles(Pt NPs)and offers abundant channels for electrolyte infiltration during the catalytic *** a result,the as-prepared Pt/GO-2850 is far active and stable than the Pt NPs supported on commercial carbon paper(Pt/CP)counterpart toward catalyzing heR,exhibiting an outstanding activity and long-term durability(300 h@10 mA·cm^(−2))in acidic/alkaline/seawater *** can be attributed to the stronger interaction between the lower-defect GO-2850 substrate and Pt,as evidenced by characterization and theoretical *** work extends further insight into the design self-supporting catalysts of high activity and stability with promising prominent application toward green energy devices.

关键词： graphene foam high graphitization Pt nanoparticles hydrogen evolution reaction long-term stability

Advanced Sensors Towards Ubiquitous Power Internet of Things

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 871-890页

作者： Jinliang he Zhifei Han Jun Hu Department of Electrical Engineering Tsinghua UniversityBeijing 100084China IEEE CSEE

The ubiquitous power Internet of Things(UPIoT)uses modern information technology and advanced communication technologies to realize interconnection and human-computer interaction in all aspects of the power *** has the characteristics of comprehensive state perception and efficient information processing,and has broad application prospects for transformation of the energy *** fundamental facility of the UPIoT is the sensor-based information *** using advanced sensors,Wireless Sensor Networks(WSNs),and advanced data processing technologies,Internet of Things can be realized in the power *** this paper,a framework of WSNs based on advanced sensors towards UPIoT is *** addition,the most advanced sensors for UPIoT purposes are reviewed,along with an explanation of how the sensor data obtained in UPIoT is utilized in various scenarios.

关键词： Advanced sensors ubiquitous power Internet of Things wireless sensor networks

Direct observation of ordered-disordered structural transition of MoS2-confined ionic liquids

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CHINESE JOURNAL OF CheMICAL ENGINEERING 2024年第8期72卷 126-132页

作者： Lu, Yumiao Ding, Weilu Li, Kun Wang, Yanlei Cao, Bobo he, Ruirui he, Hongyan Chinese Acad Sci Beijing Key Lab Ion Liquids Clean Proc CAS Key Lab Green Proc & Engn State Key Lab Mesosci & EngnInst Proc Engn Beijing 100190 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China Zhengzhou Inst Emerging Ind Technol Longzihu New Energy Lab Zhengzhou 450000 Peoples R China

Ionic liquids (ILs) are an emerging class of media of fundamental importance for chemical engineering, especially due to their interaction with solid surfaces. here, we explore the growth phenomenon of surface-confined ILs and reveal a peculiar structural transition behavior from order to disorder above a threshold thickness. This behavior can be explained by the variation of interfacial forces with increasing distance from the solid surface. Direct structural observation of different ILs highlights the influence of the ionic structure on the growth process. Notably, the length of the alkyl chain in the cation is found to be a determining factor for the ordering trend. Also, the thermal stability of surface-confined ILs is investigated in depth by controlling annealing treatments. It is found that the ordered monolayer ILs exhibit high robustness against high temperatures. Our findings provide new perspectives on the properties of surface-confined ILs and open up potential avenues for manipulating the structures of nanometer-thick IL films for various applications. (c) 2024 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

关键词： Ionic liquids (ILs) Surface-confined ILs Structural transition Thermal stability Interfacial forces FORCE-FIELD FRICTION FILMS

Experimental study on the effect of water absorption level on rockburst occurrence of sandstone

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第1期16卷 136-152页

作者： Dongqiao Liu Jie Sun Pengfei he Manchao he Binghao Cao Yuanyuan Yang State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and Technology(Beijing)Beijing100083China School of Mechanics and Civil Engineering China University of Mining and Technology(Beijing)Beijing100083China Institute for Deep Underground Science and Engineering China University of Mining and Technology(Beijing)Beijing100083China

To investigate the mechanism of rockburst prevention by spraying water onto the surrounding rocks,15 experiments are performed considering different water absorption levels on a single ***-speed photography and acoustic emission(AE)system are used to monitor the rockburst *** effect of water on sandstone rockburst and the prevention mechanism of water on sandstone rockburst are analyzed from the perspective of energy and failure *** results show that the higher the ab-sorption degree,the lower the intensity of the rockburst after absorbing water on single side of *** is reflected in the fact that with the increase in the water absorption level,the ejection velocity of rockburst fragments is smaller,the depth of the rockburst pit is shallower,and the AE energy is *** the water absorption level of 100%,the magnitude of rockburst intensity changes from medium to *** prevention mechanism of water on sandstone rockburst is that water reduces the capacity of sandstone to store strain energy and accelerates the expansion of shear cracks,which is not conducive to the occurrence of plate cracking before rockburst,and destroys the conditions for rockburst incubation.

关键词： Rockburst Water Prevention effect Crack evolution

Multiscale observation in wide-spatial radar surveillance based on coherent FDA design

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Science China(Information Sciences) 2024年第2期67卷 232-252页

作者： Lei YU Feng he Yi SU College of Electronics Science National University of Defense Technology

Wide-spatial radar surveillance missions are challenging tasks, requiring an increased power budget and agility in transmission aimed at extracting information from multiple targets in different environments. These requirements necessitate high transmitting degrees of freedom(DOF) to achieve the objective of multiscale observation for specific tasks in specialized regions of interest. herein, we exploit the multiscale observation ability in wide-spatial radar surveillance based on frequency diverse array(FDA)radar. The proposed method facilitates spatial anisotropic control of multiple radar resources, including the transmitting waveforms, beampattern, and bandwidth. By utilizing a coherent FDA radar, we offer principles for the selection of baseband waveforms, in addition to the quantitative design of the beampattern gain and optimal bandwidth from the perspective of detection. The feasibility of the proposed method is validated through numerical experiments, thus indicating the potential in wide-spatial radar surveillance. Moreover,this work can be regarded as a preliminary attempt to gauge the efficacy of the computational array, a novel academic concept.

关键词： multi-scale observation wide-spatial surveillance frequency diverse array (FDA) beampattern synthesis frequency diversity gain computational array