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Limit Theorems for Critical Galton-Watson Processes with Immigration Stopped at Zero

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Acta Mathematica Sinica,English Series 2024年第2期40卷 435-450页

作者： Dou Dou LI Mei zhang xian Yu zhang College of Statistics and Data Science Faculty of ScienceBeijing University of TechnologyBeijing 100124P.R.China Laboratory of Mathematics and Complex Systems(Ministry of Education) School of Mathematical SciencesBeijing Normal UniversityBeijing 100875P.R.China

In this paper,we consider a critical Galton-Watson branching process with immigration stopped at zero *** precise estimation on the probability generating function of the n-th population are obtained,and the tail prob... 详细信息

关键词： Branching immigration critical life period limit theorems

A robust joint frequency spectrum and power allocation strategy in a coexisting radar and communication system

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Chinese Journal of Aeronautics 2024年第10期37卷 393-409页

作者： Haowei zhang Weijian LIU Qun zhang Taiyong fei Air and Missile Defense School Air Force Engineering UniversityXi’an 710051China Air Force Early Warning Academy Wuhan 410039China Information and Navigation School Air Force Engineering UniversityXi’an 710082China

The resource allocation technique is of great significance in achieving frequency spectrum coexistence in Joint Radar-Communication(JRC)systems,by which the problem of radio frequency spectrum congestion can be well alleviated.A Robust Joint Frequency Spectrum and Power Allocation(RJFSPA)strategy is proposed for the Coexisting Radar and Communication(CRC)***,we consider the uncertainty of target Radar Cross Section(RCS)and communication channel gain to formulate a bi-objective optimization *** joint probabilities that the Crame´r-Rao Lower Bound(CRLB)of each target satisfying the localization accuracy threshold and the Communication Data Ratio(CDR)of each user satisfying the communication threshold are simultaneously maximized,under the constraint of the total power budget.A Three-Stage Alternating Optimization Method(TSAOM)is proposed to obtain the Best-Known Pareto Subset(BKPS)of this problem,where the frequency spectrum,radar power,and communicator power are allocated using the greedy search and standard convex optimization methods,*** results confirm the effectiveness of the proposed RJFSPA strategy,compared with the resource allocation methods in a uniform manner and that ignores the *** efficiency of the TSAOM is also verified by the comparison with the exhaustive search-based method.

关键词： Radar and communication system Bi-objective optimization Resource allocation Cramér-Rao lower bound Communication data ratio

Stellar parameters of main sequence turn-off star candidates observed with LAMOST and Kepler

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Research in Astronomy and Astrophysics 2017年第1期17卷 55-70页

作者： Ya-Qian Wu Mao-Sheng xiang xian-fei zhang Tan-Da Li Shao-Lan Bi Xiao-Wei Liu Jian-Ning Fu Yang Huang Zhi-Jia Tian Kang Liu Zhi-Shuai Ge Xin He Jing-Hua zhang Department of Astronomy Beijing Normal University National Astronomical Observatories Chinese Academy of Sciences Department of Astronomy Peking University

Main sequence turn-off （MSTO） stars since their ages can be robustly estimated from have advantages as indicators of Galactic evolution atmospheric parameters. Hundreds of thousands of MSTO stars have been selected from the LAMOST Galactic survey to study the evolution of the Galaxy, and it is vital to derive accurate stellar parameters. In this work, we select 150 MSTO star candidates from the MSTO star sample of xiang that have asteroseismic parameters and determine accurate stellar parameters for these stars by combining asteroseismic parameters deduced from Kepler photometry and atmospheric parameters deduced from LAMOST spectra. With this sample, we examine the age determination as well as the contamination rate of the MSTO star sample. A comparison of age between this work and xiang shows a mean difference of 0.53 Gyr （7%） and a dispersion of 2.71 Gyr （28%）. The results show that 79 of the candidates are MSTO stars, while the others are contaminations from either main sequence or sub-giant stars. The contamination rate for the oldest stars is much higher than that for younger stars. The main cause for the high contamination rate is found to be the relatively large systematic bias in the LAMOST surface gravity estimates.

关键词： stars: fundamental parameters - stars evolution - stars asteroseismology

Hybrid vibration isolation optimization of a flexible manipulator based on neural network agent model

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Chinese Journal of Aeronautics 2024年第5期37卷 482-505页

作者： Yongxin zhang Liang LI Dingguo zhang Wei-Hsin LIAO xian GUO School of Science Nanjing University of Science and TechnologyNanjing 210094China Department of Mechanical and Automation Engineering The Chinese University of Hong KongHong KongChina

Segmented Active Constrained Layer Damping(SACLD)is an intelligent vibration-damping structure,which could be applied to the sectors of aviation,aerospace,and transportation engineering to reduce the vibration of flexible ***,machine learning technology is widely used in the engineering field because of its efficient multi-objective *** dynamic simulation of a rotational segmental flexible manipulator system is presented,in which enhanced active constrained layer damping is carried out,and the neural network model of Genetic Algorithm-Back Propagation(GA-BP)algorithm is *** suppression and structural optimization of the SACLD manipulator model are studied based on vibration mode and damping *** modal responses of the SACLD manipulator model at rest and rotation are *** addition,the four model indices are optimized using the GA-BP neural network:axial incision size,axial incision position,circumferential incision size,and circumferential incision ***,the best model for vibration suppression is obtained.

关键词： Machine learning Vibration suppression Flexible manipulator Segmented active constrained layer damping Structural optimization

Accumulated-state-error-based event-triggered sampling scheme and its application to H∞ control of sampled-data systems

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Science China(Information Sciences) 2024年第6期67卷 328-341页

作者： xian-Ming zhang Qing-Long HAN Bao-Lin zhang Xiaohua GE Dawei zhang School of Science Computingand Engineering TechnologiesSwinburne University of Technology College of Automation and Electronic Engineering Qingdao University of Science & Technology School of Mathematics Shandong University

This paper is concerned with event-triggered H∞control of sampled-data systems. Its novelties lie in three aspects:（i） A novel accumulated-state-error-based event-triggered scheme is introduced by comparing the integral of the state error from tk to t with the system state sampled at tk. This condition works well due to the fact that the so-called Zeno behaviour does not occur.（ii） A novel Lyapunov functional is constructed to establish a criterion to ensure some certain H∞performance of the closed-loop system. This Lyapunov functional is dependent on the integral of the state error involved in the event-triggered scheme.（iii） Under the event-triggered sampling scheme, suitable state-feedback controllers can be designed rather than be given a priori. Moreover, a self-triggered implementation of the proposed event-triggered sampling scheme is presented as well. Finally, a batch reactor model and an inverted pendulum system are given to demonstrate the effectiveness of the proposed method.

关键词： event-triggered sampling self-triggered implementation $H_\infty$ control looped-functional

Insights into the provenance implication of leaf wax n-alkanes along the lower Yellow River

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Science China Earth Sciences 2024年第6期67卷 2001-2018页

作者： Liang zhang Jinzhao LIU Chong JIANG fei zhang Zhisheng AN School of Human Settlements and Civil Engineering Xi’an Jiaotong UniversityXi’an 710054China State Key Laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy of SciencesXi’an 710061China National Observation and Research Station of Earth Critical Zone on the Loess Plateau of Shaanxi Xi’an 710061China

Serving as one of the largest rivers in terms of both sediment and organic carbon transport fluxes in the world,the Yellow River plays a crucial role in regional biogeochemical process as well as in the global carbon ***,although a large number of studies have been carried out on the flux,composition,source and seasonal variation of total particulate organic carbon in the Yellow River so far,studies on molecular biomarkers at different spatial and temporal scales are still *** this study,we focus on the molecular and hydrogen isotopic properties of leaf wax n-alkanes among different types of samples which obtained from different seasons(flood ***-flood)along the lower Yellow *** molecular distribution of n-alkanes show that the riparian topsoils are subject to inputs from the overlying vegetation,while the suspended sediments from the flood season are characterized by the mixing of soil materials which originate from various stratigraphy with different ages on the Chinese Loess *** to the contrasting hydrodynamic conditions,the n-alkanes in suspended sediments also show distinct molecular composition between flood and non-flood ***,considering the effect of climatic factors,the proportion of monocots in flood-season suspended sediments is calculated from a semi-quantitative perspective using δ^(2)H_(wax).Our findings may bring to light new considerations for the interpretation of leaf wax proxies in studies of organic matter sources of Yellow River.

关键词： Molecular distribution Hydrogen isotopic composition Leaf wax n-alkanes Suspended sediments Lower Yellow River

Selection of dialysis methods for end-stage kidney disease patients with diabetes

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World Journal of Diabetes 2024年第9期15卷 1862-1873页

作者： Yao-Hua Hu Ya-Li Liu Ling-fei Meng Yi-xian zhang Wen-Peng Cui Department of Nephrology The Second Hospital of Jilin UniversityChangchun 130041Jilin ProvinceChina

The increasing prevalence of diabetes has led to a growing population of endstage kidney disease(ESKD)patients with ***,kidney transplantation is the best treatment option for ESKD patients;however,it is limited by the lack of ***,dialysis has become the standard treatment for ESKD ***,the optimal dialysis method for diabetic ESKD patients remains *** patients with diabetes often present with complex conditions and numerous ***,these patients face a high risk of infection and technical failure,are more susceptible to malnutrition,have difficulty establishing vascular access,and experience more frequent blood sugar fluctuations than the general ***,this article reviews nine critical aspects:Survival rate,glucose metabolism disorder,infectious complications,cardiovascular events,residual renal function,quality of life,economic benefits,malnutrition,and volume *** study aims to assist clinicians in selecting individualized treatment methods by comparing the advantages and disadvantages of hemodialysis and peritoneal dialysis,thereby improving patients’quality of life and survival rates.

关键词： Diabetes End-stage kidney disease Hemodialysis Peritoneal dialysis Dialysis methods selection

Effects of Environmental Factors on Corrosion Behavior of E690 Steel in Simulated Marine Environment

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Acta Metallurgica Sinica(English Letters) 2024年第4期37卷 678-694页

作者： Jingjing Peng Jing Liu Shen zhang Zhihui Wang xian zhang Kaiming Wu Collaborative Innovation Center for Advanced Steels Hubei Province Key Laboratory of Systems Science in Metallurgical ProcessThe State Key Laboratory of Refractories and MetallurgyWuhan University of Science and TechnologyWuhan430081China

The effects of hydrostatic pressure, dissolved oxygen, temperature and flow velocity, and their interaction on the corrosion rates of E690 high-strength steel (HSS) in simulated marine environments were studied using response surface methodology. The results show that the flow velocity exerts the most significant influence on the corrosion rate of E690 HSS. Consequently, the corrosion behavior of E690 HSS under varying flow velocities were analyzed profoundly from initial pitting corrosion to long-term corrosion properties. The results indicate that the flow state facilitates the mass transfer and enhances the adsorption tendency of Cl− by enhancing the electrochemical activity of the steel surface. These factors accelerate the electrochemical reactions, resulting in increased pitting density, depth and the long-term corrosion rates in dynamic seawater environments.

关键词： E690 steel Simulated marine environment Corrosion behavior Flow velocity Response surface methodology(RSM)

Analysis method and experimental study of ice accumulation detection signal based on Lamb waves

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Chinese Journal of Aeronautics 2024年第8期37卷 388-403页

作者： Yanxin zhang Hongjian zhang xian YI Binrui WU xianlei GUAN Jianjun XIONG Key Laboratory of Icing and Anti/De-icing China Aerodynamics Research and Development CenterMianyang 621000China State Key Laboratory of Aerodynamics China Aerodynamics Research and Development CenterMianyang 621000China

A quantitative identification method for in-flight icing has the capability to significantly enhance the safety of aircraft *** guided waves have the unique advantage of detecting icing in a relatively large area,but quantitative identification of ice layers is a *** this paper,a quantitative identification method of ice accumulation based on ultrasonic guided waves is ***,a simulation model for the wave dynamics of piezoelectric coupling in three dimensions is established to analyze the propagation characteristics of Lamb waves in a structure consisting of an aluminum plate and an ice *** wavelet transform method is utilized to extract the Time of Flight(ToF)or Time of Delay(ToD)of S_(0)/B_(1) mode waves,which serves as a characteristic parameter to precisely determine and assess the level of ice ***,an experimental system is developed to evaluate the feasibility of Lamb waves-based icing real-time detection in the presence of spray ***,a combination of the Hampel median filter and the moving average filter is developed to analyze ToF/ToD *** simulation results reveal a positive correlation between geometric dimensions(length,width,thickness)of the ice layer and ToF/ToD of B1 mode waves,indicating their potential as indicators for quantifying ice *** results of real-time icing detection indicate that ToF/ToD will reach greater peak values with the growth of the arbitrary-shaped ice layer until saturation to effectively predict the simulation *** study lays a foundation for the practical application of quantitative icing detection via ultrasonic guided waves.

关键词： Ice Ice accumulation Ultrasonic sensor Ultrasonic guided wave Lamb wave Wavelet transform