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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

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

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,I0010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 TechnologyKunming 650093YunnanChina Metallurgical Electrode Material Engineering Technology Research Center of Yunnan Province Kunming 650106YunnanChina Kunming hendera Technology Co.LTD. Kunming 650106YunnanChina

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 Pb^(2+)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： Lead-carbon battery Negative sulphation Hydrogen evolution Single-atom Lead carbon composites

Effect of SARS-CoV-2 infection in early pregnancy on placental development

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Science China(Life Sciences) 2024年第3期67卷 622-625页

作者： Shanru Yi Liping Wang Mengting Wang Wei Hong Ben Xu Xiaoying he Mengtian Yang Zhiping Wu Beiying Wang Guang Yang Shijun Shen Xinyu Cui Ruixue Wang Kai Wang Hong Wang Xiaocui Li Shaorong Gao Cizhong Jiang jiayu Chen Clinical and Translation Research Center of Shanghai First Maternity and Infant Hospital Shanghai Key Laboratory of Signaling and Disease ResearchSchool of Life Sciences and TechnologyTongji UniversityShanghai 200092China Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of the Ministry of Education Orthopaedic Department of Tongji HospitalTongji UniversityShanghai 200065China Frontier Science Center for Stem cell Research Tongji UniversityShanghai 200092China Shanghai Key Laboratory of Maternal Fetal Medicine Shanghai First Maternity and Infant HospitalSchool of MedicineTongji UniversityShanghai 201204China

Dear Editor,Since the COVID-19 pandemic, the potential risks associated with maternal SARS-CoV-2 infection and its effect on fetal development have been a subject of considerable public concern. Previous studies have ... 详细信息

关键词： pregnancy fetal Effect

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

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

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

Divergent responses of runoff to climate change in the upper basins of the Third Pole dominated by westerlies and monsoon

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Science China Earth Sciences 2024年第8期67卷 2592-2614页

作者： Qikai SUN Fengge SU he SUN State Key Laboratory of Tibetan Plateau Earth System Environment and Resources(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100101China

The diverse climates,distribution of snow and glaciers,and geographic locations directly affect the runoff response to climate change in the upper basins of the Third *** present,a comprehensive analysis of runoff variations and their distinct responses to climate change in the westerlies-and monsoon-dominated upper basins is still *** study comprehensively analyzed annual runoff variations in westerlies-dominated basins(the upper basins of the Aksu(UAKS),Syr Darya(USRD),Yarkant(UYK),Hotan(UHT),Amu Darya(UAMD),and Indus(UI))and monsoon-dominated basins(the upper basins of the Yangtze(UYA),Yellow(UYE),Lancang(ULC),Nujiang(UNJ),and Yarlung Zangbo(UYZ))of the Third Pole from 1961 *** multi-source meteorological data and large-scale circulation factors,this study investigated the divergent responses of runoff in the upper basins to climate change,and explored the large-scale circulation mechanisms underlying runoff variations in these upper *** results showed that:(1)The annual runoff in the majority of upper basins(except for the UYE and UYZ)exhibited an increasing trend,and the annual runoff in the UAKS,UYK,and UI showed a significant increasing trend from1961 to *** annual runoff in the upper basins of the Third Pole changed abruptly from decreasing to increasing between the 1980s and 2000s,with the exception of the UYE.(2)The runoff in the monsoon-dominated upper basins has been controlled primarily by changes in precipitation over the past 55 *** contrast,the runoff in the westerlies-dominated upper basins exhibited three distinct long-term responses to climate change:temperature-dominated(UYK and UHT),precipitation-dominated(USRD and UAMD),and the combined influence of precipitation and temperature(UAKS and UI).Since the 1960s,the sensitivity of runoff to warm season temperature changes in the most westerlies-dominated upper basins has decreased,while the response of runoff to precipitation changes has intensified.(3)The stud

关键词： Upper basins of the Third Pole Climate change Westerlies and monsoon Runoff variations Large-scale circulation factors