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Non-monotonic behavior of jam probability and stretchedexponential distribution in pedestrian counterflow

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Chinese Physics B 2024年第9期33卷 259-266页

作者： Ze-Hao Chen Zhi-Xi Wu Jian-Yue Guan College of Physical Science and Technology Guangxi Normal UniversityGuilin 541004China Lanzhou Center for Theoretical Physics Key Laboratory of Theoretical Physics of Gansu Provinceand Key Laboratory for Quantum Theory and Applications of the Ministry of EducationLanzhou UniversityLanzhou 730000China

We adopt a floor field cellular automata model to study the statistical properties of bidirectional pedestrian flow movingin a straight corridor. We introduce a game-theoretic framework to deal with the conflict of multiple pedestrians tryingto move to the same target location. By means of computer simulations, we show that the complementary cumulative distributionof the time interval between two consecutive pedestrians leaving the corridor can be fitted by a stretched exponentialdistribution, and surprisingly, the statistical properties of the two types of pedestrian flows are affected differently by theflow ratio, i.e., the ratio of the pedestrians walking toward different directions. We also find that the jam probability exhibitsa non-monotonic behavior with the flow ratio, where the worst performance arises at an intermediate flow ratio of around0.2. Our simulation results are consistent with some empirical observations, which suggest that the peculiar characteristicsof the pedestrians may attributed to the anticipation mechanism of collision avoidance.

关键词： traffic and crowd dynamics evolutionary game theory

MAXIMAL FUNCTION CHARACTERIZATIONS OF HARDY SPACES ASSOCIATED WITH BOTH NON-NEGATIVE SELF-ADJOINT OPERATORS SATISFYING GAUSSIAN ESTIMATES AND BALL QUASI-BANACH FUNCTION SPACES

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Acta Mathematica Scientia 2024年第2期44卷 484-514页

作者：林孝盛杨大春杨四辈袁文 laboratory of Mathematics and Complex Systems(Ministry of Education of China) School of Mathematical SciencesBeijing Normal UniversityBeijing100875China School of Mathematics and Statistics Gansu Key Laboratory of Applied Mathematics and Complex SystemsLanzhou UniversityLanzhou730000China

Assume that L is a non-negative self-adjoint operator on L^(2)(ℝ^(n))with its heat kernels satisfying the so-called Gaussian upper bound estimate and that X is a ball quasi-Banach function space onℝ^(n) satisfying some mild *** HX,L(ℝ^(n))be the Hardy space associated with both X and L,which is defined by the Lusin area function related to the semigroup generated by *** this article,the authors establish various maximal function characterizations of the Hardy space HX,L(ℝ^(n))and then apply these characterizations to obtain the solvability of the related Cauchy *** results have a wide range of generality and,in particular,the specific spaces X to which these results can be applied include the weighted space,the variable space,the mixed-norm space,the Orlicz space,the Orlicz-slice space,and the Morrey ***,the obtained maximal function characterizations of the mixed-norm Hardy space,the Orlicz-slice Hardy space,and the Morrey-Hardy space associated with L are completely new.

关键词： Hardy space ball quasi-Banach function space Gaussian upper bound estimate non-negative self-adjoint operator maximal function

Highly strengthening and toughening biomimetic ceramic structures fabricated via a novel coaxially printing

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Journal of Advanced Ceramics 2024年第4期13卷 403-412页

作者： Kunkun Song Shengda Yang Ningqi Shao Yantang Zhao Peng He Yongfeng Wei Hengzhong Fan Yongsheng Zhang Qiangqiang Zhang State Key laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China School of Civil Engineering and Mechanics Lanzhou UniversityLanzhou 730000China Key laboratory of Mechanics on Disaster and Environment in Western China(Lanzhou University) Ministry of EducationLanzhou 730000.China

Additive manufacturing technology,by manipulating and emulating inherent multiscale,multi-material,and multifunctional structures found in nature,has created new opportunities for constructing heterogeneous structures associated with special properties and achieving ultra-high mechanical performance and reliability in ceramic composite *** this study,we have developed an innovative fabrication method designated as coaxial 3D printing for the synchronous construction of two constituents into ceramic composites with a tooth enamel biomimetic ***,the stiff silicate and flexible epoxy served as a strengthening bridge and toughening layer,*** method differed from the traditional approach of randomly dispersing reinforcing components within a ceramic *** allowed for the direct creation of an internally effective three-dimensional reinforcement network structure in ceramic *** process facilitated synergistic deformation and simultaneous enhancement of multiple materials and hierarchical *** to the uniform distribution of internal stress and effective block of microcrack propagation,the biomimetically structured silicate/epoxy ceramic composite has demonstrated much significant enhancement in mechanical properties,includingcompressive strength(48.8±3.12MPa),flexuralstrength(10.39±1.23MPa),andflexuraltoughness(218.7±54.6kJ/m^(3)),which was 0.5,2.1,and 47.5 times as high as those of the intrinsic brittle silicate ceramics,***-situ characterization and multiscale finite element simulation of microstructural evolution during three-point bending deformation further validated multiple-step features of the fracture process(silicate bridge fracture,interface detachment,epoxy extraction,and rupture),which benefited from interpenetrating structural features achieved by coaxial printing to accomplish with the complex propagating routines of the crack deflection in silicate ceramic *** coaxia

关键词： coaxial 3D printing silicate ceramic composites enamel biomimetic microstructure strengthening bridge tougheninglayer crackdeflection

THE WEIGHTED KATO SQUARE ROOT PROBLEMOF ELLIPTIC OPERATORS HAVING A BMOANTI-SYMMETRICPART

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Acta Mathematica Scientia 2024年第2期44卷 532-550页

作者：马文贤杨四辈 School of Mathematics and Statistics Gansu Key Laboratory of Applied Mathematics and Complex SystemsLanzhou UniversityLanzhou730000China

Let n≥2 and let L be a second-order elliptic operator of divergence form with coefficients consisting of both an elliptic symmetric part and a BMO anti-symmetric part in ℝ^(n).In this article,we consider the weighted Kato square root problem for *** precisely,we prove that the square root L^(1/2)satisfies the weighted L^(p)estimates||L^(1/2)(f)||L_(ω)^p(R^(n))≤C||■f||L_(ω)^p(R^(n);R^(n))for any p∈(1,∞)andω∈Ap(ℝ^(n))(the class of Muckenhoupt weights),and that||■f||L_(ω)^p(R^(n);R^(n))≤C||L^(1/2)(f)||L_(ω)^p(R^(n))for any p∈(1,2+ε)andω∈Ap(ℝ^(n))∩RH_(2+ε/p),(R^(n))(the class of reverse Hölder weights),whereε∈(0,∞)is a constant depending only on n and the operator L,and where(2+ε/p)'denotes the Hölder conjugate exponent of 2+ε/***,for any given q∈(2,∞),we give a sufficient condition to obtain that||■f||L_(ω)^p(R^(n);R^(n))≤C||L^(1/2)(f)||L_(ω)^p(R^(n))for any p∈(1,q)andω∈A_(p)(R^(n))∩pRH_(q/p),(R^(n)).As an application,we prove that when the coefficient matrix A that appears in L satisfies the small BMO condition,the Riesz transform∇L^(−1/2)is bounded on L_(ω)^(p)(ℝ^(n))for any given p∈(1,∞)andω∈Ap(ℝ^(n)).Furthermore,applications to the weighted L^(2)-regularity problem with the Dirichlet or the Neumann boundary condition are also given.

关键词： elliptic operator Kato square root problem Muckenhoupt weight Riesz transform reverse Hölder inequality

A kinetic resolution accompanied chirality transformation process for asymmetric synthesis of chiral phenol,oxaziridine,andα-hydroxyl cyclic ketone

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Science China Chemistry 2024年第9期67卷 2989-2997页

作者： Pengxin Wang Xiaoyong Zhang Lingqing Wang Rui Wang Dongxu Yang Key laboratory of Preclinical Study for New Drugs of Gansu Province School of Basic Medical Sciences&Research Unit of Peptide ScienceChinese Academy of Medical SciencesLanzhou UniversityLanzhou 730000China State Key laboratory of Bioactive Substance and Function of Natural Medicines Institute of Materia MedicaChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100050China School of Sciences Great Bay UniversityDongguan 523000China Institute of Systems and Physical Biology Shenzhen Bay LaboratoryShenzhen 518055China

Chirality transformation is a basic,attractive,and important strategy for obtaining enantioenriched products with desired chiral *** reported chirality conversion reaction often involves the process from one type of chirality to another *** better utilize the chirality transformation strategy for obtaining two or more products with different chiral elements in a single reaction,a new method of kinetic resolution accompanied by a chirality transformation protocol is proposed and successfully realized in this *** process is used for the asymmetric oxidation of phenol compounds along with the kinetic resolution of oxaziridines.A wide scope of products,including axially chiral phenols,oxaziridines,andα-hydroxyl cyclic ketones were smoothly obtained in high levels of yields and enantioselectivities in the developed *** products can be readily used for the synthesis of various types of chiral ligands,which are potential choices for other catalytic asymmetric reactions.

关键词： chirality transformation kinetic resolution accompanied axially chiral phenols chiral oxaziridines

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Effects of plug tray cell size on the growth of Atractylodes Chinensis (DC) Koidz seedlings

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International Journal of Agricultural and Biological Engineering 2024年第4期17卷 45-52页

作者： Kaixuan Shi Juwen Liang Fang Ji Dongxian He Key laboratory of Agricultural Engineering in Structure and Environment of MARA College of Water Resources&Civil EngineeringChina Agricultural UniversityBeijing 100083China

Atractylodes Chinensis(DC)Koidz is a perennial herb often used as a prescription medicine for influenza,to invigorate the spleen and remove *** quality of the herb is determined by the quality of the *** traditional *** seedling production technique has nonuniform seedlings and low *** plug seedling technique was used to produce *** *** study was conducted to determine the growth characteristics of *** seedlings according to the cell size of plug trays and number of days after *** height,stem diameter,rhizome diameter,number of leaves,leaf area,and shoot dry and fresh weight of *** seedlings were significantly higher in the P32-D treatment than in the P72,P50,and P32 treatments,but not significantly different from the P28-D treatment 60 d after *** P28-D treatment resulted in a considerable drop in rhizome fresh weight and healthy seedling index,both of which are key indicators for assessing seedling *** the differences in Pn among treatments were not significantly different,Tr was considerably greater in *** seedlings treated with P32-D and P28-D than in the other three *** P32-D and P28-D treatments had considerably greater potential maximum photochemical efficiency of PSII,quantum yield of photosystem II,photochemical quenching and electron transport rate than the other three *** vitality of *** seedlings was significantly stronger in the P32-D treatment than in the other four treatments,and it was 1.9 times higher than in the P28-D *** soluble protein,soluble sugar,and starch contents of *** seedlings were highest in the P32-D treatment,but the differences among treatments were not ***,EUE,PY and ey were significantly higher in the P32-D treatment than in the other four treatments,being 1.3,1.3,1.4 and 1.4 times higher than in P28-D,*** the other hand,as for the change in the gro

关键词： Atractylodes Chinensis(DC)Koidz plug seedling plug tray cell size

A simulation study of Tsinghua Thomson scattering X-ray source

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Chinese Physics C 2009年第S2期33卷 146-150页

作者：唐传祥李任恺黄文会陈怀璧杜应超杜强杜泰斌何小中林郁正钱厚俊施嘉儒向导颜立新余沛成 Department of Engineering Physics Tsinghua University Key laboratory of Particle & Radiation Imaging (Tsinghua University) Ministry of Education ey laboratory of High Energy Radiation Imaging Fundamental Science for National Defense

Thomson scattering X-ray sources are compact and a?ordable facilities that produce short duration, high brightness X-ray pulses enabling new experimental capacities in ultra-fast science studies, and also medical and industrial applications. Such a facility has been built at the Accelerator laboratory of Tsinghua University, and upgrade is in progress. In this paper, we present a proposed layout of the upgrade with design parameters by simulation, aiming at high X-ray pulses flux and brightness, and also enabling advanced dynamics studies and applications of the electron beam. Design and construction status of main subsystems are also presented.

关键词： Thomson scattering X-ray ultra-fast brightness

钯催化下杂芳基溴代物与偕二氟烯丙基硼试剂的交叉偶联反应

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化学学报 2024年第2期82卷 105-109页

作者：张大伟赵海洋冯笑甜顾玉诚张新刚中国科学院、中国科学院大学、上海有机化学研究所、中国科学院有机氟化学重点实验室上海200032 郑州大学化学学院与河南先进技术研究院郑州450001 Syngenta Jealott’s Hill International Research Centre BracknellRG426EYUK

使用二叔丁基苯基膦预配位的氯化钯(P(t-Bu)_(2)Ph)_(2)·PdCl_(2)为催化剂,实现了钯催化下偕二氟烯丙基硼试剂与杂芳基溴代物的偶联反应.该方法不仅体系简单,反应效率高,区域选择性优秀,可以克量级制备产物,而且具有良好的官能团兼容性... 详细信息

使用二叔丁基苯基膦预配位的氯化钯(P(t-Bu)_(2)Ph)_(2)·PdCl_(2)为催化剂,实现了钯催化下偕二氟烯丙基硼试剂与杂芳基溴代物的偶联反应.该方法不仅体系简单,反应效率高,区域选择性优秀,可以克量级制备产物,而且具有良好的官能团兼容性,适用于一系列不同类型的杂环底物,为合成偕二氟烯丙基杂芳烃化合物提供了一种高效方法.

关键词：钯催化偕二氟烯丙基化杂芳基溴代物偶联反应

Applicability of different indices for delineating the boundary of arid region: A case study in northwestern China

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Journal of Earth Science 2024年

作者： Xue Peng Xiang Li Yingyibing Shen Xuehua Che Shipei Dong Zhuolun Li Key laboratory of Western China's Environmental Systems (Ministry of Education)， College of Earth and Environmental Sciences， Center for Glacier and Desert Research， Lanzhou University

Arid regions are vital components of Earth's land surface. Clarifying the area/boundary of arid region is crucial for comprehending area changes and potential mechanisms. However， the accuracy and applicability of arid region boundary delineated by different indices remain unclear. In this study， the annual precipitation （AP）， humidity index （H）， and aridity index （K） were calculated for delineating arid region of China using 106 meteorological stations during 1990–2019. The results suggest that AP and H can accurately delineate arid region， because they are consistent with the distribution of typical soil and vegetation in arid region， whereas K is not. Moreover， AP is the best index for delineating arid region in regions with limited meteorological data， especially in studying long-term patterns and mechanisms of area changes. The accuracy of delineating arid region using H is enhanced in regions with abundant meteorological data. Over the past 30 years， influenced by the increase of atmospheric moisture influx and precipitation， the area in arid region of northwestern China decreased by 70×103–90×103km2， resulting in the present area of approximately 1.55×106km2. This study provides appropriate indices for delineating arid region， contributing to improving our knowledge of regional responses difference to climate change.

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