检索结果-南通市图书馆

Design and Implementation of Nonlinear Precoding for MIMO-SDMA Toward 6G Wireless

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

China Communications 2024年第1期21卷 69-87页

作者： Chaowu wu Yue xiao Shu Fang Gang wu National Key Laboratory of Wireless Communications University of Electronic Science and Technology of ChinaChengdu 611731China

In this paper,we present a novel and robust nonlinear precoding(NLP)design and detection structure specifically tailored for multiple-input multipleoutput space division multiple access(MIMO-SDMA)systems toward 6G *** approach aims to effectively mitigate the impact of imperfect channel estimation by leveraging the channel fluctuation mean square error(MSE)for reconstructing a highly accurate precoding matrix at the ***,we introduce a simplified receiver structure that eliminates the need for equalization,resulting in reduced interference and notable enhancements in overall system *** conduct both computer simulations and experimental tests to validate the efficacy of our proposed *** results reveals that the proposed NLP scheme offers significant performance improvements,making it particularly well-suited for the forthcoming 6G wireless.

关键词： MIMO-SDMA nonlinear precoding Tomlinson-Harashima precoding(THP) vector perturbation(VP)

Optically levitated micro gyroscopes with an MHz rotational vaterite rotor

在线全文

学校读者我要写书评

暂无评论

Microsystems & Nanoengineering 2024年第3期10卷 219-227页

作者： Kai Zeng Xiangming Xu Yulie wu Xuezhong wu Dingbang xiao College of Intelligence Science and Technology National University of Defense TechnologyChangsha 410073China College of Information and Communication National University of Defense TechnologyWuhan 430000China Key Laboratory of Satellite Navigation Technology National University of Defense TechnologyChangsha 410073China

The field of levitated optomechanics has experienced significant advancements in manipulating the translational and rotational dynamics of optically levitated particles and exploring their sensing *** concept of using optically levitated particles as gyroscopes to measure angular motion has long been explored but has not yet been proven either theoretically or *** this study,we present the first rotor gyroscope based on optically levitated high-speed rotating *** gyroscope is composed of a micrometer-size ellipsoidal vaterite particle that is driven to rotate at MHz frequencies in a vacuum *** an external angular velocity is input,the optical axis deviates from its initial position,resulting in changes in the frequency and amplitude of the rotational *** analyzing these changes,the angular velocity of the input can be accurately detected,making it the smallest rotor gyroscope in the *** angular rate bias instability of the gyroscope is measured to be 0.08°/s and can be further improved to as low as 10^(−9)°/h theoretically by cooling the motion and increasing the angular moment of the levitated *** work opens a new application paradigm for levitated optomechanical systems and may pave the way for the development of quantum rotor gyroscopes.

关键词： particles rotational angular

Investigation of high rate mechanical flow followed by ignition for high-energy propellant under dynamic extrusion loading

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第2期32卷 336-347页

作者： Liying Dong Yanqing wu Kun Yang xiao Hou State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China

Investigating the ignition response of nitrate ester plasticized polyether(NEPE) propellant under dynamic extrusion loading is of great significant at least for two cases. Firstly, it helps to understand the mechanism and conditions of unwanted ignition inside charged propellant under accident ***, evaluates the risk of a shell crevice in a solid rocket motor(SRM) under a falling or overturning scene. In the present study, an innovative visual crevice extrusion experiment is designed using a dropweight apparatus. The dynamic responses of NEPE propellant during extrusion loading, including compaction and compression, rapid shear flow into the crevice, stress concentration, and ignition reaction, have been firstly observed using a high-performance high-speed camera. The ignition reaction is observed in the triangular region of the NEPE propellant sample above the crevice when the drop weight velocity was 1.90 m/s. Based on the user material subroutine interface UMAT provided by finite element software LS-DYNA, a viscoelastic-plastic model and dual ignition criterion related to plastic shear dissipation are developed and applied to the local ignition response analysis under crevice extrusion conditions. The stress concentration occurs in the crevice location of the propellant sample, the shear stress is relatively large, the effective plastic work is relatively large, and the ignition reaction is easy to occur. When the sample thickness decreases from 5 mm to 2.5 mm, the shear stress increases from 2..3 MPa to 2..6 MPa, the critical value of effective plastic work required for ignition is shortened from 12.0 μs to 730 μs, and the triangular area is easily triggering an ignition reaction. The propellant sample with a small thickness is more likely to stress concentration, resulting in large shear stress and effective work, triggering an ignition reaction.

关键词： NEPE propellant Crevice extrusion Shear flow Sample thickness Ignition reaction

Attack-Resilient Distributed Cooperative Control of Virtually Coupled High-Speed Trains via Topology Reconfiguration

在线全文

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2024年第4期11卷 1066-1068页

作者： Shunyuan xiao xiaohua Ge Qing wu the Institute of Advanced Technology Nanjing University of Posts and TelecommunicationsNanjing 210023China the School of Science Computing and Engineering TechnologiesSwinburne University of TechnologyMelbourne VIC 3122Australia the School of Engineering and Technology Central Queensland UniversityRockhampton QLD 4701Australia

Dear Editor,This letter addresses the resilient distributed cooperative control problem of a virtually coupled train convoy under stochastic disturbances and cyber *** main purpose is to achieve distributed coordinati... 详细信息

关键词： prescribed Speed trains

Imide-pillared covalent organic framework protective films as stable zinc ion-conducting interphases for dendrite-free Zn metal anodes

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2024年第10期97卷 470-477,I0010页

作者： xiaoman Ye Xuemei xiao Zhijing wu Xin wu Lin Gu Sheng Liu School of Chemical Engineering and Technology Sun Yat-sen UniversityZhuhai 519082GuangdongChina The Key Lab of Low-Carbon Chemistry&Energy Conservation of Guangdong Province Sun Yat-sen UniversityGuangzhou 510275GuangdongChina

The notorious growth of zinc dendrite and the water-induced corrosion of zinc metal anodes(ZMAs)restrict the practical development of aqueous zinc ion batteries(AZIBs).In this work,a zinc metallized,imide-pillared covalent organic framework(ZPC)protective film has been engineered as a stable Zn^(2.)ion-conducting interphase to modulate interfacial kinetics and suppress side reactions for *** to bare Zn,ZPC@Zn exhibits a higher Zn^(2.)ionic conductivity,a larger Zn^(2.)transference number,a lower electronic conductivity,a smaller desolvation activation energy and correspondingly a significant suppression of corrosion,hydrogen evolution and Zn ***,the ZPC@Zn||ZPC@Zn symmetric cell obtains a cycling lifespan over 3000 h under 5 mA cm^(-2.for 1 mA h cm^(-2..The ZPC@Zn||NH_(4)V_(4)O_(10)coin-type full battery delivers a specific capacity of 195.8 mA h g^(-1)with a retention rate of78.5%at 2.A g^(-1)after 1100 cycles,and the ZPC@Zn||NH_(4)V_(4)O_(10) pouch full cell shows a retention of70.1%in reversible capacity at 3 A g^(-1)after 1100 *** present incorporation of imide-linked covalent organic frameworks in the surface modification of ZMAs will offer fresh perspectives in the search for ideal protective films for the practicality of AZIBs.

关键词： Aqueous zinc ion batteries Zinc metal anodes Surface modification Covalent organic frameworks Imide linkage

A fuse-based DC circuit breaker with vacuum interrupter enhanced by an external transverse magnetic field

在线全文

学校读者我要写书评

暂无评论

High Voltage 2024年第3期9卷 710-720页

作者： Yu xiao Yi wu Yifei wu Fei Yang Mingzhe Rong Zhuo Yang State Key Laboratory of Electrical Insulation and Power Equipment School of Electric EngineeringXi'an Jiaotong UniversityXi'anChina State Grid Shaanxi Electric Power Company Limited Xi'anChina

Due to the increasing power system capacity,the interruption of large fault currents has gradually become a major challenge in power *** the moment,such currents are interrupted mainly via circuit breakers based on the method of active current ***,these types of circuit breakers tend to be costly and *** possible alternative—a fuse-based circuit breaker with current commutation process enhanced by an external transverse magnetic field(ETMF)—is proposed by the *** main advantage lies in the fast current commutation achieved by an ETMF-enhanced three-stage increase of the vacuum arc *** study of the current commutation process is mainly represented by the authors,and the influencing factors of the current commutation—contact opening speed and ETMF current—are *** last,the proposed circuit breaker is verified by an experiment,whose results show that a short-circuit current of 42.kA can be interrupted within just 2.ms.

关键词： vacuum transverse interrupt

Quantitative Analysis of Seeing with Height and Time at Muztagh-Ata Site Based on ERA5 Database

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2024年第1期24卷 87-95页

作者： xiao-Qi wu Cun-Ying xiao Ali Esamdin Jing Xu Ze-Wei Wang Luo xiao Institute for Frontiers in Astronomy and Astrophysics Beijing Normal UniversityBeijing 102206China Department of Astronomy Beijing Normal UniversityBeijing 100875China Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China

Seeing is an important index to evaluate the quality of an astronomical *** estimate seeing at the Muztagh-Ata site with height and time quantitatively,the European Centre for Medium-Range Weather Forecasts reanalysis database(ERA5)is *** calculated from ERA5 is compared consistently with the Differential Image Motion Monitor seeing at the height of 12.*** show that seeing decays exponentially with height at the Muztagh-Ata *** decays the fastest in fall in 2.2. and most slowly with height in *** seeing condition is better in fall than in *** median value of seeing at 12.m is 0.89 arcsec,the maximum value is1.2. arcsec in August and the minimum is 0.66 arcsec in *** median value of seeing at 12.m is 0.72.rcsec in the nighttime and 1.08 arcsec in the *** is a combination of annual and about biannual variations with the same phase as temperature and wind speed indicating that seeing variation with time is influenced by temperature and wind *** Richardson number Ri is used to analyze the atmospheric stability and the variations of seeing are consistent with Ri between *** quantitative results can provide an important reference for a telescopic observation strategy.

关键词： site testing atmospheric effects methods:data analysis telescopes Earth

Effect of Mn addition on microstructure and mechanical properties of GX40CrNiSi2.-12.austenitic heat resistant steel

在线全文

学校读者我要写书评

暂无评论

China Foundry 2024年第3期21卷 205-212页

作者： Guan-yu Jiang Meng-wu wu xiao-guang Yang Hui Wang Yu-yuan Zhu Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan University of TechnologyWuhan 430070China Hubei Longzhong Laboratory Xiangyang 441000HubeiChina Wescast Industries(China)Co. Ltd.Wuhan 430100China

Three types of steels were designed on the basis of GX40CrNiSi2.-12.austenitic heat resistant steel by adding different Mn contents(2.t.%,6wt.%,and 12.t.%).Thermodynamic calculation,microstructure characterization and mechanical property tests were conducted to investigate the effect of Mn addition on the microstructure and mechanical properties of the austenitic heat resistant *** show that the matrix structure in all the three types of steels at room temperature is completely *** NbC and M_(2.)C_(6)precipitate at grain boundaries of austenite *** the increase of Mn content,the number of carbides increases and their distribution becomes more *** the Mn content increases from 1.99%to 12.06%,the ultimate tensile strength,yield strength and elongation increase by 14.6%,8.0%and 46.3%,*** improvement of the mechanical properties of austenitic steels can be explained by utilizing classic theories of alloy strengthening,including solid solution strengthening,precipitation strengthening,and grain *** increase in alloy strength can be attributed to solid solution strengthening and precipitation strengthening caused by the addition of *** improvement of the plasticity of austenitic steels can be explained from two aspects:grain refinement and homogenization of precipitated phases.

关键词： austenitic heat resistant steel manganese microstructure mechanical properties

Microstructural and thermal properties of coal measure sandstone subjected to high temperatures

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2024年第8期16卷 2909-2921页

作者： Weijing xiao Dongming Zhang Shujian Li Mingyang wu School of Civil Engineering and Architecture East China Jiaotong UniversityNanchang330013China State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing400044China Yunnan Phosphate Chemical Group Co. Ltd.Kunming650600China National Engineering and Technology Research Center for Development and Utilization of Phosphate Resources Kunming650600China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China

To study the microscopic structure,thermal and mechanical properties of sandstones under the influence of temperature,coal measure sandstones from Southwest China are adopted as the research object to carry out high-temperature tests at 2.℃-1000℃.The microscopic images of sandstone after thermal treatment are obtained by means of polarizing microscopy and scanning electron microscopy(SEM).Based on thermogravimetric(TG)analysis and differential scanning calorimetric(DSC)analysis,the model function of coal measure sandstone is explored through thermal analysis kinetics(TAK)theory,and the kinetic parameters of thermal decomposition and the thermal decomposition reaction rate of rock are *** the uniaxial compression experiments,the stress‒strain curves and strength characteristics of sandstone under the influence of temperature are *** results show that the temperature has a significant effect on the microstructure,mineral composition and mechanical properties of *** particular,when the temperature exceeds 400℃,the thermal fracture phenomenon of rock is obvious,the activity of activated molecules is significantly enhanced,and the kinetic phenomenon of the thermal decomposition reaction of rock appears *** mechanical properties of rock are weakened under the influence of rock thermal fracture and mineral thermal *** research results can provide a reference for the analysis of surrounding rock stability and the control of disasters caused by thermal damage in areas such as underground coal gasification(UCG)channels and rock masses subjected to mine fires.

关键词： Rock mechanics Coal measure sandstone Micromorphology Thermal damage