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Physical mechanism of the rapid increase in intense and long-lived extreme heatwaves in the Northern Hemisphere since 1980

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Science China Earth Sciences 2024年第7期67卷 2103-2121页

作者： Yuqing WANG wen ZHOU Chunzai WANG Key Laboratory of Polar Atmosphere-ocean-ice System for Weather and Climate of the MOE Department of Atmospheric and Oceanic Sciences&Institute of Atmospheric SciencesFudan UniversityShanghai 200438China Key Laboratory for Polar Science of the MNR Polar Research Institute of ChinaShanghai 201209China State Key Laboratory of Tropical Oceanography South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China Global Ocean and Climate Research Center South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China

Since 1980,both the intensity and duration of summer heatwaves in the middle and high latitudes of the Northern Hemisphere have significantly increased,leading this region to become a critical area for a significant increase in the frequency of intense and long-lived extreme *** found that stronger and more persistent high-pressure systems and lower soil moisture before the events were the main drivers of intense and long-lived extreme heatwaves in western Europe and the middle and high latitudes of North ***,in eastern Europe and Siberia,lower cloud cover before events is also a main driver of this type of extreme heatwave,in addition to the above *** factors are coupled with each other and can change heatwave intensity and duration by influencing surface radiation processes during *** the self-organizing map classification method,we found that 6 weather patterns with increased frequency,intensity,and duration were the main dynamic reasons leading to the increase in intense and long-lived extreme heatwaves after *** addition,the decrease in summer average soil moisture in most areas of the mid-high latitudes of the Northern Hemisphere and the decrease in average cloud cover in eastern Europe and Siberia are found to be the main thermodynamic reasons leading to the increase in these extreme heatwaves.

关键词： High intensity Long duration Extreme heatwaves High pressure system Soil moisture Cloud cover

On Some Sums Involving Small Arithmetic Functions

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Acta Mathematica Sinica,English Series 2024年第10期40卷 2497-2518页

作者： wen Guang ZHAI Department of Mathematics China University of Mining and Technology

Let f be any arithmetic function and define S_f（x）:=Σn≤xf （[x/n]）.If the function f is small,namely,f （n）﹤﹤ nε,then the error term E_f（x） in the asymptotic formula of S_f（x） has the form O(x1/2+ε).In this paper,we shall study the mean square of E_f（x） and establish some new results of E_f（x） for some special functions.

关键词： 11L07 11N37 asymptotic formula exponential sum Small arithmetic function

Study of inter-well interference in shale gas reservoirs by a robust production data analysis method based on deconvolution

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Petroleum Science 2024年第4期21卷 2502-2519页

作者： wen-Chao Liu Cheng-Cheng Qiao Ping Wang wen-Song Huang Xiang-wen Kong Yu-Ping Sun He-Dong Sun Yue-Peng Jia School of Civil and Resource Engineering University of Science and Technology Beijing PetroChina Research Institute of Petroleum Exploration and Development

In order to overcome the defects that the analysis of multi-well typical curves of shale gas reservoirs is rarely applied to engineering, this study proposes a robust production data analysis method based on deconvolution, which is used for multi-well inter-well interference research. In this study, a multi-well conceptual trilinear seepage model for multi-stage fractured horizontal wells was established, and its Laplace solutions under two different outer boundary conditions were obtained. Then, an improved pressure deconvolution algorithm was used to normalize the scattered production data. Furthermore, the typical curve fitting was carried out using the production data and the seepage model solution. Finally,some reservoir parameters and fracturing parameters were interpreted, and the intensity of inter-well interference was compared. The effectiveness of the method was verified by analyzing the production dynamic data of six shale gas wells in Duvernay area. The results showed that the fitting effect of typical curves was greatly improved due to the mutual restriction between deconvolution calculation parameter debugging and seepage model parameter debugging. Besides, by using the morphological characteristics of the log-log typical curves and the time corresponding to the intersection point of the log-log typical curves of two models under different outer boundary conditions, the strength of the interference between wells on the same well platform was well judged. This work can provide a reference for the optimization of well spacing and hydraulic fracturing measures for shale gas wells.

关键词： Shale gas Inter-well interference Deconvolution Production data analysis Typical curves Multi-stage fractured horizontal well

Viscoelastic inorganic glass as solid-state electrolyte for batteries

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Journal of Materiomics 2024年第3期10卷 707-708页

作者： Yaoyu Ren Ce-wen Nan School of Materials Science and Engineering State Key Lab of New Ceramics and Fine ProcessingTsinghua UniversityBeijing100084China

A most recent exciting research result in the area of solid-state batteries that has been accepted for publication by the journal Nature Energy is *** research designed a new type of inorganic solid electrolyte named“viscoelastic inorganic glass(VIGLAS)”electrolyte with the compositions of LiAlCl_(2.5)O_(0.75)and NaAlCl_(2.5)O_(0.75).The newly developed solid electrolyte material showcases an excep-tional degree of deformability at room temperature,high ionic conductivity(>1 mS/cm at room tem-perature)and high oxidation stability(up to 4.3 V ***^(+)/Li or Na^(+)/Na).Using it as a catholyte enables a facile fabrication and a stable operation under practical stack pressure(<0.1 MPa)of all-solid-state *** represents a new path in the design of promising solid electrolytes for realizing high performance all-solid-state batteries.

关键词： Viscoelastic Inorganic glass Solid electrolyte Lithium battery Sodium battery

An Approximation Algorithm Based on Seeding Algorithm for Fuzzy k-Means Problem with Penalties

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Journal of the Operations Research Society of China 2024年第2期12卷 387-409页

作者： wen-Zhao Liu Min Li School of Mathematics and Statistics Shandong Normal UniversityJinan 250014ShandongChina

As a classic NP-hard problem in machine learning and computational geometry,the k-means problem aims to partition the given dataset into k clusters according to the minimal squared Euclidean *** from k-means problem and most of its variants,fuzzy k-means problem belongs to the soft clustering problem,where each given data point has relationship to every center *** to fuzzy k-means problem,fuzzy k-means problem with penalties allows that some data points need not be clustered instead of being paid *** this paper,we propose an O(αk In k)-approximation algorithm based on seeding algorithm for fuzzy k-means problem with penalties,whereαinvolves the ratio of the maximal penalty value to the minimal ***,we implement numerical experiments to show the effectiveness of our algorithm.

关键词： Approximation algorithm Seeding algorithm Fuzzy k-means problem with penalties

Study on metal recovery process and kinetics of oxidative leaching from spent LiFePO_(4)Li-batteries

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Chinese Journal of Chemical Engineering 2024年第4期68卷 94-102页

作者： Xiaoming Zhang wen Xie Xiaolei Zhou wenjie Zhang Jiawei wen Xin Wang Guoyong Huang Shengming Xu College of New Energy and Materials China University of PetroleumBeijing 102249China State Key Laboratory of Heavy Oil Processing College of Chemical EngineeringChina University of PetroleumBeijing 102249China Beijing Spacecrafts Beijing 100094China Ganfeng Lithium Group Co. Ltd.Xinyu 338000China Institute of Nuclear and New Energy Technology Tsinghua UniversityBeijing 100084China Beijing Key Laboratory of Fine Ceramics Tsinghua UniversityBeijing 100084China

A green environmental protection and enhanced leaching process was proposed to recover all elements from spent lithium iron phosphate(LiFePO_(4)) lithium *** order to reduce the influence of Al impurity in the recovery process,NaOH was used to remove *** impurity removal,the spent LiFePO_(4) cathode material was used as raw material under the H_(2)SO_(4) system,and the pressure oxidation leaching process was adopted to achieve the preferential leaching of *** E-pH diagram of the Fe-P-Al-H_(2)O system can determine the stable region of each element in the recovery process of spent LiFePO_(4)*** the optimal conditions(500 r·min^(-1),15 h,363.15 K,0.4 MPa,the liquid-solid ratio was 4:1 ml·g^(-1)and the acid-material ratio was 0.29),the leaching rate of Li was 99.24%,Fe,Al,and Ti were 0.10%,2.07%,and 0.03%,*** Fe and P were precipitated and recovered as FePO_(4)·2H_(2)*** kinetic analysis shows that the process of high-pressure acid leaching of spent LiFePO_(4) materials depends on the surface chemical *** the life cycle assessment(LCA)of the spent LiFePO_(4) whole recovery process,eight midpoint impact categories were selected to assess the impact of recovery *** results can provide basic environmental information on production process for recycling industry.

关键词： Spent LiFePO_(4)Li-batteries Oxidative leaching Kinetic study Life cycle assessment

Equivalence between the internal observability and equation

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Applied Mathematics(A Journal of Chinese Universities) 2024年第1期39卷 89-97页

作者： LIU wen-jun TU Zhi-yu School of Mathematics and Statistics Nanjing University of Information Science and TechnologyNanjing 210044China

This paper is concerned with a third order in time linear Moore-Gibson-Thompson equation which describes the acoustic velocity potential in ultrasound wave *** by the work of Kaltenbacher,Lasiecka and Marchand(Control Cybernet.2011,40:971-988),we establish an observability inequality of the conservative problem,and then discuss the equivalence between the exponential stabilization of a dissipative system and the internal observational inequality of the corresponding conservative system.

关键词： Moore-Gibson-Thompson equation internal observability exponential stability

Noninvasive beam diagnosis based on the TM_(010)mode

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Nuclear Science and Techniques 2024年第7期35卷 115-125页

作者： Chuang-Ye Song wen-Hui Huang Department of Engineering Physics Tsinghua University BeijingBeijing100084China of Education Beijing100084China

A resonant cavity based on the TM_(010)mode is an effective tool for noninvasive beam characterization. This technique has the advantages of a high signal-to-noise ratio, compact structure, and is related to multiple parameters compared with other beam monitors. In this study, high-precision measurements of the bunch charge, arrival time, bunch length, and energy parameters based on the TM_(010)mode are discussed. A cavity beam arrival time monitor(BAM) utilizing a phase cavity has been widely used in many facilities. Regarding bunch-length measurements, the influence of the beam energy, beam offset,and longitudinal spectrum on the TM_(010)mode are carefully considered to reduce errors, and the theoretical resolution of two cavities with different frequencies is analyzed. Owing to the dependence of the beam velocity of the beam loss factor, this method can also be used for the detection low beam energy using two cavities with the same frequency but different cavity lengths. A set of three cavities with different lengths and frequencies of 1.902 and 11.424 GHz is presented for measuring the four aforementioned parameters.

关键词： TM_(010)mode Noninvasive diagnosis Beam length Low energy

Extending Structures for Gel'fand-Dorfman Bialgebras

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Acta Mathematica Sinica,English Series 2024年第2期40卷 619-638页

作者： Jia Jia wen Yan Yong HONG School of Mathematics Hangzhou Normal UniversityHangzhou 311121P.R.China

Gel'fand-Dorfman bialgebra,which is both a Lie algebra and a Novikov algebra with some compatibility condition,appeared in the study of Hamiltonian pairs in completely integrable *** also emerged in the description of a class special Lie conformal algebras called quadratic Lie conformal *** this paper,we investigate the extending structures problem for Gel'fand-Dorfman bialgebras,which is equivalent to some extending structures problem of quadratic Lie conformal ***,given a Gel'fand-Dorfman bialgebra(A,o,[.,.]),this problem is how to describe and classify all Gel'fand-Dorfman bialgebra structures on a vector space E(A⊂E)such that(A,o,[.,.])is a subalgebra of E up to an isomorphism whose restriction on A is the identity *** by the theories of extending structures for Lie algebras and Novikov algebras,we construct an object gH2(V,A)to answer the extending structures problem by introducing the notion of a unified product for Gel'fand-Dorfman bialgebras,where V is a complement of A in *** particular,we investigate the special case when dim(V)=1 in detail.

关键词： Gel'fand-Dorfman bialgebra Lie conformal algebra Extending structures problem Novikovalgebra