检索结果-南通市图书馆

The concept of suAS/DL-based system for detecting and classifying abandoned small firearms

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2023年第12期30卷 23-31页

作者： Jungmok ma Oleg A.Yakimenko Department of Defense Science Korea National Defense University(KNDU)Republic of Korea Department of Systems Engineering Naval Postgraduate School(NPS)USA

Military object detection and identification is a key capability in surveillance and *** is a major factor in warfare effectiveness and warfighter ***,portable,and rapidly deployable small unmanned aerial systems(s uAS)in conjunction with powerful deep learning(DL)based object detection models are expected to play an important role for this *** prove overall feasibility of this approach,this paper discusses some aspects of designing and testing of an automated detection system to locate and identify small firearms left at the training range or at the *** a system is envisioned to involve an s uAS equipped with a modern electro-optical(EO)sensor and relying on a trained convolutional neural network(CNN).Previous study by the authors devoted to finding projectiles on the ground revealed certain challenges such as small object size,changes in aspect ratio and image scale,motion blur,occlusion,and *** study attempts to deal with these challenges in a realistic operational scenario and go further by not only detecting different types of firearms but also classifying them into different *** study used a YOLOv2CNN(Res Net-50 backbone network)to train the model with ground truth data and demonstrated a high mean average precision(m AP)of 0.97 to detect and identify not only small pistols but also partially occluded rifles.

关键词： Small firearms Object detection Deep learning Small unmanned aerial systems

CoDetect: cooperative anomaly detection with privacy protection towards uAV swarm

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第5期67卷 325-326页

作者： Teng LI Weiguo LIN Ruichen ma Zhuo ma Yulong SHEN Jianfeng ma School of Cyber Engineering Xidian University School of Computer Science and Technology Xidian University

As mission scenarios grow more complex, the role of a single unmanned aerial vehicle(uAV) is limited. The uAV swarm,surpassing the single uAV, dynamically establishes temporary communication networks, ensuring high transmission rates and expansive communication coverage [1]. unlike a single uAV, a swarm faces increased security risks, requiring specific capabilities.(1) Anomalies detection.

关键词： unmanned aerial vehicles (uAV)

Effect of heat treatment on the microstructure,mechanical properties and fracture behaviors of ultra-high-strength SiC/Al-Zn-Mg-Cu composites

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and materials 2024年第10期31卷 2233-2243页

作者： Guonan ma Shize Zhu Dong Wang Peng Xue BolüXiao Zongyi ma Shi-changxu Innovation Center for Advanced materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Centre of Excellence for Advanced materials Dongguan 523808China

A high-zinc composite,12vol%SiC/Al-13.3 Zn-3.27 Mg-1.07Cu(wt%),with an ultra-high-strength of 781 MPa was success-fully fabricated through a powder metallurgy method,followed by an extrusion *** effects of solid-solution and aging heat treat-ments on the microstructure and mechanical properties of the composite were extensively *** with a single-stage sol-id-solution treatment,a two-stage solid-solution treatment(470℃/1 h+480℃/1 h)exhibited a more effective solid-solution strengthen-ing owing to the higher degree of solid-solution and a more uniform *** to the aging hardness curves of the com-posite,the optimized aging parameter(100℃/22 h)was *** the aging temperature and time resulted in finer and more uniform nanoscale precipitates but only yielded a marginal increase in tensile *** fractography analysis revealed that intergranu-lar cracking and interface debonding were the main fracture mechanisms in the ultra-high-strength SiC/Al-Zn-Mg-Cu *** regions,such as the SiC/Al interface containing numerous compounds and the precipitate-free zones at the high-angle grain boundaries,were identified as significant factors limiting the strength enhancement of the *** compounds,including MgO,MgZn2,and Cu5Zn8,reduced the interfacial bonding strength,leading to interfacial debonding.

关键词： metal matrix composites heat treatment interfacial reaction mechanical properties fracture mechanism

Advanced silicon nanostructures derived from natural silicate minerals for energy storage and conversion

在线全文

学校读者我要写书评

暂无评论

Green Energy & Environment 2022年第2期7卷 205-220页

作者： Hao Wan Wei ma Kechao Zhou Yijun Cao Xiaohe Liu Renzhi ma School of Chemical Engineering Zhengzhou UniversityZhengzhou450001China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha410083China International Center for materials Nanoarchitectonics(WPI-maNA) National Institute for Materials Science(NIMS)Namiki 1-1TsukubaIbaraki305-0044Japan

To effectively alleviate the ever-increasing energy crisis and environmental issues,clean and sustainable energy-related materials as well as the corresponding storage/conversion devices are in urgent ***(Si) with the second most elemental abundance on the crust in the form of silicate or silica(SiO_(2)) minerals,is an advanced emerging material showing high performance in energy-related fields(***,photocatalytic hydrogen evolution).For the improved performance in industry-scale applications,Si materials with delicate nanostructures and ideal compositions in a massive production are highly *** account of the reserve,low cost and diverse micro-nanostructures,silicate minerals are proposed as promising raw *** the article,crystal structures and the reduction approaches for silicate minerals,as well as recent progress on the as-reduced Si products for clean energy storage/conversion,are presented ***,some cutting-edge fields involving Si materials are discussed,which may offer deep insights into the rational design of advanced Si nanostructures for extended energy-related fields.

关键词： minerals massive silicate

MODIFIED ALTERNATING POSITIVE SEMIDEFINITE SPLITTING PRECONDITIONER FOR TIME-HARMONIC EDDY CuRRENT MODELS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational mathematics 2021年第5期39卷 733-754页

作者： Yifen Ke Changfeng ma College of mathematics and Informatics FJKLmaA Fujian Normal UniversityFuzhou 350117China

In this paper,we consider a modified alternating positive semidefinite splitting preconditioner for solving the saddle point problems arising from the finite element discretization of the hybrid formulation of the time-harmonic eddy current *** eigenvalue distribution and an upper bound of the degree of the minimal polynomial of the preconditioned matrix are studied for both simple and general *** results demonstrate the effectiveness of the proposed preconditioner when it is used to accelerate the convergence rate of Krylov subspace methods such as GMRES.

关键词： Time-harmonic eddy current model Saddle point problem Eigenvalue distribution Preconditioner

Two-stage aging treatment to accelerate aging kinetics without impairing strength in B_4C/7A04Al composite

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2024年第8期67卷 2485-2492页

作者： CHEN YunTao ma GuoNan ZHu ShiZe WANG Dong XIAO BoLv ma ZongYi Shi-Changxu Innovation Center for Advanced materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Centre of Excellence for Advanced materials Dongguan 523808China

Aging treatments are the key process to obtain satisfactory strength for 7xxxAl alloys and their composites. However, traditional single-stage(SS) aging is time-consuming to reach a peak strength condition. In this study, an efficient 120℃ + 160℃ two-stage(TS) aging treatment was proposed on a B_4C/7A04Al composite fabricated via powder metallurgy(PM) technology, which could acquire similar peak-aging strength but only took about 15% of the time compared to traditional 120℃ SS aging. The evolution of precipitation during the TS aging was investigated, as well as those of the 7A04Al alloys for comparison. In the second stage aging process, the higher aging temperature accelerated the nucleation of η′ phases inside the grains and thus increased the density of precipitates. Moreover, the short aging time limited the coarsening of precipitates and the broadening of precipitatefree zones. The above factors were beneficial for quickly obtaining satisfactory precipitation strengthening effects. The B_4C/7A04Al composite exhibited slower aging kinetics than the 7A04Al alloy in the TS aging. Mg elements consumption by the chemical reaction between B impurities introduced by B_4C particles and the Al matrix was considered to potentially retard the aging kinetics of the B_4C/7A04Al composite. Nevertheless, the precipitation sequence was not affected.

关键词： aluminum matrix composites aging treatment powder metallurgy mechanical properties precipitation

Deep geothermal resources in China:Potential,distribution,exploitation,and utilization

在线全文

学校读者我要写书评

暂无评论

Energy Geoscience 2023年第4期4卷 11-24页

作者： Yongsheng ma China Petroleum&Chemical Corporation Beijing100728China

Deep geothermal resources mainly refer to the thermal energy stored in subsurface rocks and fluids therein at a depth of 3-10 km,which is a kind of renewable and sustainable clean energy unaffected by weather and seasonal *** scale exploitation of the deep geothermal resources is of great significance to ensuring national energy security and achieving the“Carbon Peak and Carbon Neutrality”.Based on the latest terrestrial heat flow data,this paper estimated the potential of deep geothermal resources in the terrestrial areas of China,and the results show that the total amount of geothermal resources within 3e10 km under the Earth's surface in the terrestrial areas of China is 24.6×10^(15)*** line with climate zones categorized,the geothermal resource proportion is 43.81%for severe cold regions,29.19%for cold regions,6.92%for mild regions,13.82%for hot summer and cold winter regions,and 6.26%for hot summer and warm winter *** according to the burial depth range reveal that the resources within depth ranges of 3-5 km,5-7 km and 7-10 km under the Earth's surface are 4.3119×10^(15)GJ,6.37674×10^(15)GJ and 13.89594×10^(15)GJ respectively,showing an increasing trend of geothermal potential with increasing burial *** deep geothermal resources are mainly of medium-to-high temperature reserves,and the energy supply strategy can be optimized by combining the climate conditions and population distribution,as well as considering power *** regions of cold or severe cold climate,the geothermal resources may be applied to geothermal power generation and district heating in combination;in regions of hot summer and cold winter or mild climates,the resources can be used for geothermal power generation combined with cooling and heating;in regions of hot summer and warm winter climates,the resources may be applied to geothermal power generation combined with cooling and industrial and agricultural *** of deep geothermal reso

关键词： China terrestrial area Deep geothermal resource Resource potential utilization strategy Deployment recommendation

Ageing Hardening Mechanism and Corrosion Resistance in the Fe65Cr13Cu3(CoMnMoNiAlTi)19 Medium-Entropy Stainless Alloy

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2021年第11期34卷 1601-1608页

作者： Ben-Qi Xu Hui Zhang Dong ma Qun-Shuang ma Li-Zhai Pei Key Laboratory of Green Fabrication and Surface Technology of Advanced Metal materials(Ministry of Education) Anhui University of Technology243002Ma'anshanChina School of materials Science and Engineering Anhui University of TechnologyMa'anshan 243002China

The ageing hardening mechanism of a newly designed Fe65Cr13Cu3(CoMnMoNiAlTi)19 medium-entropy stainless alloy(ME-SA)with a simple bcc solid solution matrix was *** kind of ME-SA possessed a higher ageing hardness of approximately 584 HV and higher compressive stress and corrosion resistance than those of the conventional precipitation hardening stainless steel 17-4 PH(Cr17Ni4Cu4 Nb),which has comparable compressive *** well-dispersed B2-ordered phase in the cast state transformed to a D03 crystal structure with a higher ordering degree and reduced the precipitate size after ageing at 500℃,thus promoting a great ageing hardening effect.

关键词： Medium-entropy stainless alloy Ordered phase transition Aging hardening Corrosion resistance

Feasible synthesis of porous h-BN by Mg^(2+)induced lattice dislocations for hydrogen and ammonia storage

在线全文

学校读者我要写书评

暂无评论

Nano Research 2025年第1期18卷 94-99页

作者： Xiaojia Huang Zihao Wang Yihan Kong Li Jiang Baolin Wang Jiangtao Jia Heping ma Guangshan Zhu Key Laboratory of Polyoxometalate and Reticular material Chemistry of Ministry of Education Northeast Normal UniversityChangchun 130024China School of Chemical Engineering and Technology Xi’an Jiaotong university Xi’an 710049China

Hexagonal boron nitride(h-BN)is a two-dimensional(2D)layered material with a structure similar to graphite and it has potential as a hydrogen and ammonia storage ***,dense packing in the standard h-BN structure limits its surface area and prevents the B and N from being adsorption *** this study,the addition of Mg^(2+)during h-BN synthesis facilitated the growth of lattice dislocations and led to a crosslinked three-dimensional(3D)porous structure.A proposed formation mechanism for porous h-BN was confirmed by several characterization routes,most clearly by high-resolution transmission electron microscopy(HRTEM).Porous Mg/BNs exhibited high H_(2)and NH_(3)uptakes and showed potential for H_(2)and NH_(3)storage.

关键词： hexagonal boron nitride porous material dislocation gas storage