检索结果-南通市图书馆

Rare Metals 2024年第11期 5652-5663页

作者： Yang Liu Ke Tan Sen Liu Xu Zhang mao-qiang shen Xue-Sen Liu Xin-Yue Gao Lin-Rui Hou Chang-Zhou Yuan School of Materials Science & Engineering University of Jinan

The shuttling diffusion of polysulfides is a bottleneck that seriously limits the performance of Li-S *** construction of sulfur cathodes with reliable trapping ability of polysulfides is the key to overcome such ***,a hierarchical porous architecture,i.e.,Co（OH）2sheets bonded Ti3C2TxMXene aerogel(Co（OH）2/MXA),is constructed via a facile selfassembled approach and used as an efficient free-standing polysulfides *** interconnected three-dimensional（3D） porous network with void space and strong interfacial interaction not only enables high sulfur loading but facilitates fast ion and electron *** and theoretical results confirm the hetero-framework exhibits outstanding immobilization and conversion ability for polysulfides due to its polar surface and bifunctional catalytic activities toward both formation and decomposition of *** optimized Co（OH）2/MXA cathode delivers excellent rate capability(407 mAh·g-1at 5C) with a sulfur loading of 2.7 mg·cm-2,and ultra-stable cycling performance as an extremely small capacity decay of～0.005% per cycle within 1700 cycles at 1C is achieved with a high sulfur loading of 6.7 mg·*** significantly,our design structural/componential methodology here promises the MXene-based aerogel electrodes for LiS batteries and beyond.

关键词：

Precise Asymptotics in Limit Theorems for a Supercritical Branching Process with Immigration in a Random Environment

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2024年第8期40卷 1850-1874页

作者： Chun mao HUANG Rui ZHANG Zhi qiang GAO Department of Mathematics Harbin Institute of Technology(Weihai)Weihai 264209P.R.China School of Mathematical Sciences Beijing Normal UniversityBeijing 100875P.R.China

Let(Zn)be a supercritical branching process with immigration in an independent and identically distributed random *** necessary moment conditions,we show the exact convergence rate in the central limit theorem on log Zn and establish the corresponding local limit theorem by using the moments of the natural submartingale and the convergence rates of its *** similar approach and with the help of a change of measure,we also present the so-called integrolocal theorem and integral large deviation theorem to characterize the precise asymptotics of the upper large deviations.

关键词： Branching process with immigration random environment central limit theorem large deviation

A toroidal SAW gyroscope with focused IDTs for sensitivity enhancement

在线全文

学校读者我要写书评

暂无评论

Microsystems & Nanoengineering 2024年第2期10卷 47-56页

作者： Lu Tian Haitao Zhao qiang shen Honglong Chang Ministry of Education Key Laboratory of Micro and Nano Systems for Aerospace School of Mechanical EngineeringNorthwestern Polytechnical UniversityXi’an710072China

A surface acoustic wave(SAW)gyroscope measures the rate of rotational angular velocity by exploiting a phenomenon known as the SAW gyroscope *** a gyroscope is a great candidate for application in harsh environments because of the simplification of the suspension vibration mechanism necessary for traditional microelectromechanical system(MEMS)***,for the first time,we propose a novel toroidal standing-wave-mode SAW gyroscope using focused interdigitated transducers(FIDTs).Unlike traditional SAW gyroscopes that use linear IDTs to generate surface acoustic waves,which cause beam deflection and result in energy dissipation,this study uses FIDTs to concentrate the SAW energy based on structural features,resulting in better focusing performance and increased SAW *** experimental results reveal that the sensitivity of the structure is 1.51µV/(°/s),and the bias instability is 0.77°/s,which are improved by an order of magnitude compared to those of a traditional SAW ***,the FIDT component can enhance the performance of the SAW gyroscope,demonstrating its superiority for angular velocity *** work provides new insights into improving the sensitivity and performance of SAW gyroscopes.

关键词： angular deflection gyroscope

Absolute pose estimation of UAV based on large-scale satellite image

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第6期37卷 219-231页

作者： Hanyu WANG qiang shen Zilong DENG Xinyi CAO Xiaokang Wang School of Mechatronical Engineering Beijing Institute of TechnologyBeijing 100081China Beijing Institute of Technology Chongqing Innovation Center Chongqing 401120China

Obtaining absolute pose based on pre-loaded satellite images is one of the important means of autonomous navigation for small Unmanned Aerial Vehicles(UAVs)in Global Navigation Satellite System(GNSS)denied *** of the previous works have tended to build Convolutional Neural Networks(CNNs)to extract features and then directly regress the pose,which will fail when solving the challenges caused by the huge viewpoint and size differences between“UAV-satellite”image pairs in real-world ***,this paper proposes a probability distribution/regression integrated deep model with the attention-guided triple fusion mechanism,which estimates discrete distributions in pose space and three-dimensional vectors in translation *** order to overcome the shortage of the relevant dataset,this paper simulates image datasets captured by UAVs with forward-facing cameras during target searching and autonomous *** effectiveness,superiority,and robustness of the proposed method are verified by simulated datasets and flight tests.

关键词： Satellite imagery Unmanned Aerial Vehicle(UAV) Deep neural networks Vision navigation von Mises-Fisher distribution

Coinfection of SARS-CoV-2 Omicron variant and other respiratory pathogens in children

在线全文

学校读者我要写书评

暂无评论

World Journal of Pediatrics 2024年第1期20卷 92-96页

作者： Wei Li Bing-Han Wang Bao-Hai Chen Yi Sun Lin Li Wen-Qing Xiang Ahmed Faisal Ali Lin-Xuan Su Hai-Yan mao Hong-qiang shen qiang Shu Department of Clinical Laboratory Children's HospitalNational Clinical Research Center for Child HealthZhejiang University School of MedicineHangzhouChina School of Public Health Zhejiang University School of MedicineHangzhouChina Department of Information Center Children's HospitalZhejiang University School of MedicineHangzhouChina Zhejiang Provincial Center for Disease Control and Prevention HangzhouChina Department of Thoracic&Cardiovascular Surgery Children's HospitalNational Clinical Research Center for Child HealthZhejiang University School of MedicineHangzhouChina

Since the outbreak of coronavirus disease 2019(COVID-19),the entire world has been affected by the epidemic[1,2].On November 9,2021,a variant of the novel coronavirus B.1.1.529 was detected for the first time from case samples in South *** Omicron strain spread and mutated significantly *** variant has the characteristics of escape immunity,which can induce relatively extreme disease and reduce the neutralization of antibodies in vaccinators,and is more likely to be reinfected[3,4].The clinical presentation of severe acute respiratory syndrome coronavirus 2(SARSCoV-2)in children has mild symptoms and a lower risk of hospitalization and death.

关键词： respiratory immunity acute

A review on Bi_(2)WO_(6)-based photocatalysts synthesis, modification, and applications in environmental remediation, life medical, and clean energy

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Environmental Science & Engineering 2024年第7期18卷 87-108页

作者： Wei mao Xuewu shen Lixun Zhang Yang Liu Zehao Liu Yuntao Guan Guangdong Provincial Engineering Technology Research Center for Urban Water Cycle and Water Environment Safety Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China State Environmental Protection Key Laboratory of Microorganism Application and Risk Control School of EnvironmentTsinghua UniversityBeijing 100084China

Photocatalysis has emerged a promising strategy to remedy the current energy and environmental crisis due to its ability to directiy convert clean solar energy into chemical *** tungstate(Bi_(2)WO_(6))has been shown to be an excellent visible light response,a well-defined perovskite crystal structure,and an abundance of oxygen atoms(providing efficient channels for photogenerated carrier transfer)due to their suitable band gap,effective electron migration and separation,making them ideal *** has been extensively applied as photocatalyst in aspects including pollutant removal,carbon dioxide reduction,solar hydrogen production,ammonia synthesis by nitrogen photocatalytic reduction,and cancer *** this review,the fabrication and application of Bi_(2)WO_(6) in photocatalysis were comprehensively *** photocatalytic properties of BizwO-based materials were significantly enhanced by carbon modification,the construction of heterojunctions,and the atom doping to improve the photogenerated carrier migration rate,the number of surface active sites,and the photoexcitation ability of the *** addition,the potential development directions and the existing challenges to improve the photocatalytic performance of Bi_(2)WO_(6)-based materials were discussed.

关键词： Bismuth tungstate Synthesis and modification Photocatalytic application Environmental remediation Clean energy Medical science

Effects of environment and genotype-by-environment interaction on phenotype of Rorippa elata(Brassicaceae),an endemic alpine plant in the Hengduan mountains

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Plant Ecology 2024年第4期17卷 42-55页

作者： Zhi-qiang Du Yao-Wu Xing Ting-shen Han CAS Key Laboratory of Tropical Forest Ecology Xishuangbanna Tropical Botanical GardenChinese Academy of SciencesMengla 666303China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Plant Diversity and Specialty Crops Xishuangbanna Tropical Botanical GardenChinese Academy of SciencesMengla 666303China

Global climate change poses a severe threat to mountain *** plasticity and local adaptation are two common strategies for alpine plant to cope with such *** may facilitate organismal adaptation to contrasting environments,depending on the influences of the environment or genotype or their interacted *** this study,we use an endemic alpine plant(Rorippa elata)in the Hengduan mountains(HDM)to unravel its phenotypic basis of adaptation strategy and evaluate the relative contributions of environment and genotype to its *** transplanted 37 genotypes of *** into two common gardens across low and high elevations(2800 vs.3800 m)during *** fitness-related traits were measured,including flowering probability and glucosinolates(GS)*** estimated the environmental or genotypic contributions to the phenotype and identified the main environmental *** results revealed that both environment and genotype-by-environment interactions contributed to the phenotypes of *** heterogeneity was identified as a key factor that explained 24%of the total phenotypic *** particular,genotypes of the northern HDM showed significantly higher plasticity in flowering probability than those of the southern ***,within the southern HDM,GS content indicated local adaptation to herbivory stresses for *** genotypes along *** conclusion,our results suggest that *** may have adapted to the alpine environment through species-level plasticity or regional-level local *** processes were shaped by either complex topography or interactions between genotype and mountain *** study provides empirical evidence on the adaptation of alpine plants.

关键词： alpine plant common garden genotype-by-environment Hengduan mountains local adaptation phenotypic plasticity

Accurate simulations of pure-viscoacoustic wave propagation in tilted transversely isotropic media

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Petroleum Science 2024年第2期21卷 866-884页

作者： qiang mao Jian-Ping Huang Xin-Ru Mu Ji-Dong Yang Yu-Jian Zhang Geosciences Department China University of Petroleum(East China)Qingdao266580ShandongChina Pilot National Laboratory for Marine Science and Technology(Qingdao) Qingdao266207ShandongChina

Forward modeling of seismic wave propagation is crucial for the realization of reverse time migration(RTM) and full waveform inversion(FWI) in attenuating transversely isotropic media. To describe the attenuation and anisotropy properties of subsurface media, the pure-viscoacoustic anisotropic wave equations are established for wavefield simulations, because they can provide clear and stable wavefields. However, due to the use of several approximations in deriving the wave equation and the introduction of a fractional Laplacian approximation in solving the derived equation, the wavefields simulated by the previous pure-viscoacoustic tilted transversely isotropic(TTI) wave equations has low accuracy. To accurately simulate wavefields in media with velocity anisotropy and attenuation anisotropy, we first derive a new pure-viscoacoustic TTI wave equation from the exact complex-valued dispersion formula in viscoelastic vertical transversely isotropic(VTI) media. Then, we present the hybrid finite-difference and low-rank decomposition(HFDLRD) method to accurately solve our proposed pure-viscoacoustic TTI wave equation. Theoretical analysis and numerical examples suggest that our pure-viscoacoustic TTI wave equation has higher accuracy than previous pure-viscoacoustic TTI wave equations in describing q P-wave kinematic and attenuation characteristics. Additionally, the numerical experiment in a simple two-layer model shows that the HFDLRD technique outperforms the hybrid finite-difference and pseudo-spectral(HFDPS) method in terms of accuracy of wavefield modeling.

关键词： Pure-viscoacoustic TTI wave equation Attenuation anisotropy Seismic modeling Low-rank decomposition method

Attitude control of multi-spacecraft systems on SO(3)with stochastic links failure

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第3期37卷 320-331页

作者： KANG Zeyu shen qiang WU Shufan Chris J.DAMAREN MU Zhongcheng School of Aeronautics and Astronautics Shanghai Jiao Tong UniversityShanghai 200240China Institute for Aerospace Studies University of TorontoTorontoOntario M3H 5T6Canada

In this paper,for Multi-Spacecraft System(MSS)with a directed communication topology link and a static virtual leader,a controller is proposed to realize attitude consensus and attitude stabilization with stochastic links failure and actuator ***,an MSS attitude error model suitable for a directed topology link and with a static virtual leader based on SO(3)is derived,which considers that the attitude error on SO(3)cannot be defined based on algebraic ***,we design a controller to realize the MSS on SO(3)with attitude consensus and attitude stabilization under stochastic links failure and actuator ***,the simulation results of a multi-spacecraft system with stochastic links failure and a static virtual leader spacecraft are demonstrated to illustrate the efficiency of the attitude controller.

关键词： Multi-spacecraft systems Attitude consensus Attitude stabilization Stochastic links failure Super-martingale convergence

Current-carrying tribological behavior of C/Cu contact pairs in extreme temperature and humidity environments for railway catenary systems

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2024年第8期67卷 2537-2548页

作者： shen MingXue JI DeHui HU qiang XIAO Li LI QiuPing State Key Laboratory of Performance Monitoring and Protecting of Rail Transit Infrastructure East China Jiaotong UniversityNanchang 330013China School of Materials Science and Engineering East China Jiaotong UniversityNanchang 330013China Institute of Applied Physics Jiangxi Academy of SciencesNanchang 330095China

Many current-carrying contact pairs, such as those found in pantograph-catenary systems, operate in open environments and are susceptible to significant external interference from temperature and humidity variations. This study investigated the evolution of the friction coefficient and contact resistance of C/Cu contact pairs under alternating temperature, humidity, and current conditions. Through experimentation, the wear rate and microtopography of the worn surface were analyzed under various constant parameters. Subsequently, the differences in tribological behavior and current-carrying characteristics of the contact pairs under these three parameters were explored. The results revealed that the decrease in temperature resulted in a significant increase in the friction coefficient of the contact pairs, carbon wear, and copper surface roughness. Additionally, the surface oxidation rate was lower at lower temperatures. Moreover, contact resistance did not consistently increase with decreasing temperature, owing to the combined action of the contact area and the oxide film. Compared with temperature, humidity fluctuations at room temperature exerted less influence on the friction coefficient and contact resistance of the contact pairs. Dry environments rendered carbon materials vulnerable to oxidation and cracking, while excessive humidity fostered abrasive wear and arcing. High-current conditions generally degraded the tribological properties of C/Cu contacts. In the absence of current, the friction coefficient was extremely high, and the copper transfer was high. Under excessive current, copper was susceptible to plowing by carbon micro-bumps and abrasive particles, resulting in a decrease in the friction coefficient. The release of lipids from the carbon surface due to temperature elevation weakened the electrical contact performance and increased the occurrence of arc erosion, thereby exacerbating carbon wear.

关键词： temperature/humidity pantograph-catenary system C/Cu wear current-carrying friction sliding electrical contact