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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

relevance of hybrid artificial intelligence for improving the forecasting accuracy of natural resource prices

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Geoscience Frontiers 2024年第3期15卷 431-446页

作者： mei li rida Waheed Dervis Kirikkaleli Ghazala Aziz School of Management and Economics and Shenzhen Finance Institute The Chinese University of Hong KongShenzhen(CUHK-Shenzhen)China department of Finance and Economics College of BusinessUniversity of JeddahJeddahSaudi Arabia European university of Lefke Faculty of Economic and Administrative ScienceDepartment of Banking and FinanceLefkeTurkey department of Business Administration College of Administrative and Financial SciencesSaudi Electronic UniversityJeddahSaudi Arabia

The prediction performance of traditional forecasting methods is low due to the high level of complexity in a series of energy *** present study attempts to compare the traditional regression,machine learning tools and hybrid models to conclude the outperforming *** first step is to propose the effective denoising technique for Tadawul energy index,which has confirmed the superiority of CSD based ***,we use the CSD-ArIMA,CSD-ANN,and CSD-rNN as hybrid *** a result,CSD-rNN outperforms both other models in terms of MSE,MApE,rMSE and *** findings are useful for policy makers,investors and portfolio managers to forecast the energy trends,and hedge the portfolio risk accordingly.

关键词： Hybrid artificial intelligence CSD denoising technique Forecasting Energy prices Saudi Arabia

Old pinus massoniana forests benefit more from recent rapid warming in humid subtropical areas of central-southern china

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Journal of Forestry research 2024年第5期35卷 155-170页

作者： Wenxin li liangjun zhu lianhua zhu Mengdan Jing Censhi Qian Yu zhu paolo Cherubini College of life Science and Technology Central South University of Forestry and TechnologyChangsha 410004People’s Republic of China Swiss Federal Institute for Forest Snow and Landscape Research WSL8903 BirmensdorfSwitzerland department of Forest and Conservation Sciences Faculty of ForestryUniversity of British Columbia2004-2424 Main MallVancouverBC V6T 1Z4Canada

Trees progress through various growth stages,each marked by specific responses and adaptation strate-gies to environmental *** the importance of age-related growth responses on overall forest health and management policies,limited knowledge exists regarding age-related effects on dendroclimatic relationships in key subtropical tree *** this study,we employed a den-drochronological method to examine the impact of rapid warming on growth dynamics and climatic sensitivity of young(40–60 years)and old(100–180 years)pinus mas-soniana forests across six sites in central-southern *** normalized log basal area increment of trees in both age groups increased significantly following rapid warming in *** in young forests further showed a distinct growth decline during a prolonged severe drought(2004–2013),whereas those in old forests maintained growth *** growth was more strongly influenced by temperature than by moisture,particularly in old *** tem-peratures strongly and positively impacted the growth of old trees but had a weaker effect on young *** forests had a significantly lower resistance to extreme drought but faster recovery compared to young ***“divergence problem”was more pronounced in younger forests due to their heightened sensitivity to warming-induced drought and heat *** ongoing warming,young forests also may initially experience a growth decline due to their heightened sensitivity to winter *** findings underscore the importance of considering age-dependent changes in forest/tree growth response to warming in subtropical forest man-agement,particularly in the context of achieving“Carbon peak&Carbon Neutrality”goals in china.

关键词： Tree rings pinus massoniana Age effects Drought resilience Subtropical forests rapid warming

Weak minimum aberration and maximum number of clear two-factor interactions in 2_(IV)^(m-p)designs

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Science china Mathematics 2005年第11期48卷 1479-1487页

作者： YANG Guijun,liU Minqian & ZHANG runchu department of Statistics, tianjin university of Finance and Economics, tianjin 300222, china department of Statistics, School of Mathematical Sciences and LpMC, nankai university, tianjin 300071, china department of Statistics Tianjin University of Finance and Economics Tianjin China department of Statistics School of Mathematical Sciences and LPMC Nankai University Tianjin China

Both the clear effects and minimum aberration criteria are the important rules for the design selection. In this paper, it is proved that some 2IVm-p designs have weak minimum aberration, by considering the number of clear two-factor interactions in the designs. And some conditions are provided, under which a 2IVm-p design can have the maximum number of clear two-factor interactions and weak minimum aberration at the same time. Some weak minimum aberration 2IVm-p designs are provided for illustrations and two non-isomorphic weak minimum aberration 2IV13-6 designs are constructed at the end of this paper.

关键词： clear weak minimum aberration resolution wordlength pattern.

Defect-manipulated magnetoresistance and above-room-temperature ferromagnetism in two-dimensional BaNi_(2)V_(2)O_(8)

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Chinese Chemical Letters 2024年第3期35卷 523-527页

作者： pengfei Tan Chuanhui zhu Jinjin Yang Shuang Zhao Tao Xia mei-Huan Zhao Tao Han Zheng Deng Man-rong li Key Laboratory of Bioinorganic and Synthetic chemistry of Ministry of Education School of ChemistrySun Yat-sen UniversityGuangzhou 510006China School of Science and Engineering The Chinese University of Hong KongShenzhen 518172China Institute of physics Chinese Academy of SciencesBeijing 100190China School of Science Hainan UniversityHaikou 570228China

The intricate correlation between multiple degrees of freedom and physical properties is a fascinating area in solid state chemistry and condensed matter ***,we report a quantum-magnetic system BaNi_(2)V_(2)O_(8)(BNVO),in which the spin correlation was modulated by unusual oxidation state,leading to different magnetic *** BNVO was modified with topochemical reduction(Tr)to yield Tr-BNVO with partially reduced valance state of Ni^(+)in the two-dimensional NiO_(6)-honeycomb ***,the antiferromagnetic order is suppressed by the introduction of locally interposed Ni^(+)and oxygen vacancies,resulting in a ferromagnetic ground state with the transition temperature up to 710 K.A positive magnetoresistance(7.5%)was observed in the Tr-BNVO at 40 K under 7 *** findings show that topological reduction is a powerful approach to engineer low-dimensional materials and accelerate the discovery of new quantum magnetism.

关键词： Layered honeycomb oxide Topochemical reduction Oxygen vacancies Ferromagnetism Magnetoresistance

A Low Cost, Green Sustainable and Biodegradable Biomass-based Fluorine-free Water and Oil repellent

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Chinese Journal of polymer Science 2024年第4期42卷 480-491页

作者： Zhi-Wei Shen Shu-Feng Hu Chen Zeng Wei-Qing Kong mei-Fang zhu State Key Laboratory for Modification of Chemical Fibers&polymer Materials College of Materials Science and EngineeringDonghua UniversityShanghai201620China State Key Laboratory of pulp and paper Engineering School of Light Industry and EngineeringSouth China University of TechnologyGuangzhou510630China

With the global ban on plastics intensifying, the substitution of plastic with paper has garnered increasing attention. However, the inadequate water and oil repellency of pulp molding hinders its practical applications. Currently, the common method to enhance the oil and water repellency of pulp molding is by adding fluorinated water and oil repellents. Nevertheless, fluorinated compounds are environmentally and physiologically harmful. Therefore, the development of fluorine-free, water and oil repellent alternatives is crucial. In this study, chitosan and stearic acid were utilized as the first and second layers of the oil and water repellent coatings, respectively. The coated samples exhibited favorable water repellency, with a water contact angle of 116.4°, and excellent oil repellency, achieving a 12/12 rating on the kit scale. Importantly, the samples did not exhibit any leakage after being soaked in hot water and hot oil at 95±5℃ for 30 min, demonstrating remarkable performance as a barrier against hot water and oil. Moreover, the coated samples displayed outstanding mechanical properties, thermal stability, biodegradability, and recyclability. The approach presented in this study is simple, cost-effective, environmentally friendly, and represents a promising technique for producing fluoride-free, oil-and water-resistant pulp molding products.

关键词： Biomass Fluoride-free Oil-andwater-resistant plasticfree

Editorial for the Special Issue on Emerging Technology and Advanced Application of Nondestructive Detection for power Equipment

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Chinese Journal of Electrical Engineering 2024年第1期10卷 1-2页

作者： li J. mei H. li S. tianjin university China Tsinghua Shenzhen International Graduate School China Lanzhou Jiaotong university China

The rapid development of clean and renewable energy technologies represented by wind and solar energy,as well as the continuous growth of load demand,have put forward higher requirements for the safe operation of the power *** performance of power equipment based on traditional dielectric materials is often limited by various defects generated during molding,transportation,assembly,and operation,which cannot meet the reliability requirements of power systems in the new *** detection is an essential technical method in industrial development,which can detect and evaluate the defect and damage status of in-service equipment,key components,and materials without damaging the object.

关键词： service Application operation

Optical Transient Source AT2021lfa:A possible“Dirty Fireball”

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research in Astronomy and Astrophysics 2024年第4期24卷 124-133页

作者： Xue-mei Ye Da-Ming Wei Yi-Ming zhu Zhi-ping Jin Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210023China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China National Astronomical Observatories/Nanjing Institute of Astronomical Optics&Technology Chinese Academy of SciencesNanjing 210042China CAS Key Laboratory of Astronomical Optics&Technology Nanjing Institute of Astronomical Optics&TechnologyNanjing 210042China

AT2021lfa,also known as ZTF21aayokph,was detected by the Zwicky Transient Facility on 2021 May 4,a 05:34:48 ***-up observations were conducted using a range of ground-based optical telescopes,as wel as Swift/XrT and VLA ***2021lfa is classified as an“orphan afterglow”candidate due to its rapid flux decline and its reddened color(g-r=0.17±0.14 mag).For an optical transient source without promp gamma-ray detection,one key point is to determine its burst *** we measure the burst time through fitting the initial bump feature of AT2021lfa and obtain its burst time as 2021 May 3,at 22:09:50 *** afterglowpy,we model the multi-band afterglow of AT2021lfa and find that the standard model canno reproduce the late radio observations *** that the microphysical parameters ε_(e),ε_(B)(the energy fraction given to electrons and magnetic field),andξN(the fraction of accelerated electrons)may vary with time we then model the afterglow of AT2021lfa taking into account the temporal evolution of the physical parameters ε_(e),ε^(B),and ξ_(N) and find in this case the multi-wavelength observations can be reproduced *** initial Lorentz factor of AT2021lfa can be estimated from the peak time of the early afterglow,which yields a value of about 18 suggesting that AT2021lfa should be classified as a“dirty fireball.”From the upper limit for the prompt emission energy of AT2021lfa,we obtain that the radiation efficiency is less than 0.02%,which is much smaller than that of ordinary gamma-ray bursts(GrBs).It is also interesting that the fitted values of jet angle and viewing angle are very large,θ_(c)~0.66 rad,θ_(v)~0.53 rad,which may lead to the low Lorentz factor and radiation *** compared with GrB afterglow samples,it is evident that the onset bump timescale of AT2021lfa satisfies the empirical relationships observed in GrB ***,the luminosity of AT2021lfa falls within the range of observations for GrB samples;howeve

关键词： gamma-rays:ISM methods:numerical radiation mechanisms:non-thermal

Hypothesis Testing for Arbitrarily Varying Source

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Acta Mathematica Sinica,English Series 1996年第1期12卷 33-39页

作者： Fu Fangwei Shen Shiyi department of Mathematics nankai university tianjin, 300071 china 南开大学数学系天津

Hypothesis testing for arbitrarily varying source (AVS), which is to decide between the two hypotheses for the varying behavior of the distribution of AVS, is considered in this paper. We determine the best asymptotic exponent of the second kind of error probability when the first kind of error probability is fixed. This result generalizes the well-known lemma of Stein in statistics. As a corollary, Strassen’s coding theorem for AVS is obtained.

关键词： Hypothesis testing Stein lemma Arbitrarily varying source Coding theorem