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AN ANALYSIS FOR IMPERFECT SENSITIVITY OF A SUPERCONDUCTING ROD

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Acta Mechanica Solida Sinica 1996年第3期9卷 236-245页

作者： Xiao, Y Zhu, yy LANZHOU UNIV DEPT MECHLANZHOU 730000PEOPLES R CHINA

On the basis of the interaction between the electromagnetic field and a solid, the imperfect sensitivity of a superconducting rod is studied in this paper. The influences of the initial deflection of the rod and the initial magnetic field on the stability are discussed. One can see that the bifurcation response of the rod with imperfections is similar to the universal unfolding of the fork bifurcation from the singularity theory.

关键词： magneto-elasticity superconducting rod imperfect sensitivity bifurcation figure

Reconstructing forest and grassland cover changes in China over the past millennium

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Science China Earth Sciences 2025年第1期 94-110页

作者： fanneng HE fan YANG Yafei WANG Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Key Research Institute of Yellow River Civilization and Sustainable Development Henan University University of Chinese Academy of Sciences

Historical forest and grassland cover changes not only are critical indicators for quantifying ecological and environmental change processes but also serve as fundamental data for long-term climate change simulations and terrestrial ecosystem carbon emission assessments. However, because of limitations in historical data, quantitative estimations and spatially gridded reconstructions of these changes remain challenging, necessitating further methodological exploration. This study focused on China's present-day land area over the past millennium, objectively capturing the characteristics and drivers of forest and grassland cover changes. On this basis, using the forest transition theory and the space-for-time substitution method, we depicted the historical deforestation process as an inverted “S” curve and developed a model to reconstruct historical forest area changes based on the functional relationship between the forest area and population size dynamics. Subsequently, a gridded forest allocation model was established on the basis of deforestation tendencies. For the grassland cover, we implemented regionspecific methods, such as the cropland area deduction method and the habitat constraint method, to quantitatively reconstruct historical changes. Consequently, we obtained provincial forest and grassland area changes over the past millennium and mapped 10-km-resolution gridded data of forest and grassland cover. The results indicated the following.(1) The methods developed using population data as a proxy objectively reproduced the spatiotemporal evolution of forest and grassland cover in China over the past millennium. These feasible methods offer a novel pathway for the quantitative reconstruction of historical forest and grassland cover changes.(2) The data indicated that China's forest area generally decreased over the past millennium, characterized by a “decrease-then-increase” pattern. The forest area experienced three distinct phases: a slow decline(AD 1000

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Growth behavior and electronic regulation of Pt on various Mo-based supports for hydrogen evolution electrocatalysis

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Science China Chemistry 2025年

作者： Lulu Chen Yichao Huang Jiajun Wang Meihong Liao Zhiyuan Liu Meiqi Liu Hanqing Cai Lin Wang Lidong Gao Dawei Hu Lianming Zhao Ning Pu Zhuangjun fan State Key Laboratory of Chemical Safety School of Materials Science and Engineering China University of Petroleum (East China) School of Mechanical and Electronic Engineering Qingdao Binhai University Qingdao Chuangqi New Energy Catalysis Technology Co.Ltd. Sinopec Research Institute of Petroleum Processing Co.Ltd. Institute of Energy Hefei Comprehensive National Science Center

Insight into the growth behavior and electronic regulation of platinum （Pt） on various transition metal supports is paramount in developing high-performing electrocatalysts for hydrogen evolution reactions （HER）.Herein,we studied the influence of molybdenum-based supports （MoX,X=C,N,P,and S） on the growth behavior and electronic regulation of *** found that the formation energy variations between Pt single atom and clusters on MoX supports play a pivotal role in the growth behavior of ***,the electronic regulation of Pt induced by metal-support interaction may reflect the valence changes of Pt in Pt-MoX/*** Pt-MoC/C catalyst with a moderate valence state of Pt exhibits the best HER activity with an overpotential of 12.0 mV at 10 mA cm-2and a mass activity of 27.1 A mgPt-1,12.3 times as high as that of commercial 20 wt% Pt/*** work provides constructive guidance for the design of high-performance HER catalysts.

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Dynamic Analysis and Numerical Simulation of a Kind of Arrestor Arresting Buckle Propagation by FEM

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China Ocean Engineering 1998年第3期13卷 323-332页

作者： Huang, yy Qian, Q Jin, T Huazhong Univ Sci & Technol Dept Mech Wuhan 430074 Peoples R China

For exact estimation of efficiency of a buckle arrestor, it is necessary to take the effect of structural inertia into account in the analysis of buckle propagation on elastic structures after meeting arrestors. Under this consideration, this paper deals with the dynamics of buckle arrest and its numerical simulation on the basis of the beam system model used by Chater and Hutchinson (1983). The FEM combined with an improving are-length control method is adopted to solve the dynamic equations describing the arresting of buckle propagation. A new group of parameters for arrestor design which differs greatly from that by the quasi-static analysis is obtained. The present results support the conclusion that the inertia of the beam cannot be neglected in such analysis.

关键词： buckle propagation arrestor beam nonlinear foundation finite element method

Computation of Design Load and Motion for Floating Structures Navigating in Waves

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China Ocean Engineering 1999年第1期14卷 93-100页

作者： Wang, yy Zhu, RC Miao, J Dalian Univ Technol Sch Naval Architecture & Marine Engn Dalian 116024 Peoples R China

Analytical and numerical investigation is made of the source potential for-floating structure with forward speed in waves. A particular form is selected for numerical applications, where the double integral of the Green function is transformed into the single one and the oscillation characteristics for integrands in the specific computation domain are treated numerically. A comparison of calculated examples with published data is given and it shows that the numerical simulation is satisfactory and the accuracy is adequate to engineering application.

关键词： floating structure Green function ship motion source distribution

金属卤素钙钛矿CsPbBr3的电声耦合输运特性研究

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原子与分子物理学报 2025年第2期42卷 169-174页

作者：杨帆周贤中广东工业大学集成电路学院广州510006

金属卤素钙钛矿CsPbBr_(3)在发光方面(Light emitter)的优良表现吸引了许多人把它作为下一代发光、显示与量子信息的可选材料,但其关键的漂移迁移率会受到声子限制.本文将以第一性原理计算得到CsPbBr_(3)的包括极性光学声子(Polar optic... 详细信息

金属卤素钙钛矿CsPbBr_(3)在发光方面(Light emitter)的优良表现吸引了许多人把它作为下一代发光、显示与量子信息的可选材料,但其关键的漂移迁移率会受到声子限制.本文将以第一性原理计算得到CsPbBr_(3)的包括极性光学声子(Polar optical phonon)在内的电声耦合特性,然后使用线性玻尔兹曼方程给出在电场下的解,从而得出漂移迁移率.在论文详述中会给出CsPbBr_(3)的各向异性载流子输运特性的研究,为金属卤素钙钛矿的应用提供一些必要信息.

关键词：第一性原理计算电子-声子耦合漂移迁移率

基于IWOA-LSTM算法的预应力钢筋混凝土梁损伤识别

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江苏大学学报（自然科学版） 2025年第1期46卷 105-112,119页

作者：范旭红章立栋杨帆李青郁董凯江苏大学土木工程与力学学院江苏镇江212013 河南省公路工程局集团第二公路工程有限公司河南郑州450015 中国葛洲坝集团第二工程有限公司四川成都610091

为准确识别桥梁结构的损伤程度,制作了桥梁的关键构件——预应力钢筋混凝土梁,进行三点弯曲加载试验.收集了损伤破坏全过程的声发射(AE)信号,通过AE信号参数分析,将梁的损伤破坏过程划分为4个典型阶段.构建了长短时记忆神经网络(LSTM)模... 详细信息

为准确识别桥梁结构的损伤程度,制作了桥梁的关键构件——预应力钢筋混凝土梁,进行三点弯曲加载试验.收集了损伤破坏全过程的声发射(AE)信号,通过AE信号参数分析,将梁的损伤破坏过程划分为4个典型阶段.构建了长短时记忆神经网络(LSTM)模型,根据经验设置LSTM模型的超参数容易导致网络陷入局部最优而影响了分类结果,提出采用Sine混沌映射和自适应权重来改进鲸鱼优化算法(WOA),对LSTM进行超参数寻优.设计了IWOA-LSTM算法模型,训练识别试验梁各损伤阶段的AE信号特征参数.定型网络结构,并识别同种工况下其他梁的AE信号.结果表明:IWOA-LSTM算法模型识别准确率均超过或接近92%,相较于普通LSTM模型,IWOA-LSTM模型识别准确率提高了约7%.

关键词：预应力钢筋混凝土梁声发射损伤识别长短时记忆神经网络改进的鲸鱼优化算法

SYNTHESIS　OF　PROPYLENE　GLYCOL　AND　DIMETHYL　CARBONATE　USING　POLYMER－SUPPORTED　CATALYSTS

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Chinese Chemical Letters 1996年第6期7卷 519-522页

作者： Zhu, H Chen, LB Jiang, yy ACAD SINICA GUANGZHOU INST CHEMGUANGZHOU 510650PEOPLES R CHINA ACAD SINICA INST CHEMBEIJING 100080PEOPLES R CHINA

Two types of effective transesterification catalysts including ordinary anion exchange resinsand polymer-supported triphenyl phosphines are used to synthesize propylene glycol anddimethyl carbonate from propylene carbonate and methanol. The experimental results show thatthe products can be obtained under moderate conditions using these catalysts. Triphenylphosphine polymeric catalysts are found thermally stable by thermogravimetry (TG)

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Synthesis of chiral phosphine derivatives through a copper（I）-catalyzed desymmetric SNAr reaction

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Science China Chemistry 2025年

作者： Shuai Zhang Pei-Zhi Liu Yan-Bo Li Qi Zhang Jun-Zhao Xiao Yi-fan Wang Tian-Yu Wei Jia-Wei Jiang Ye Wang Qian Peng Liang Yin Key Laboratory of Fluorine and Nitrogen Chemistry and Advanced Materials Shanghai Institute of Organic Chemistry University of Chinese Academy of Sciences Chinese Academy of Sciences State Key Laboratory of Elemento-Organic Chemistry and Tianjin Key Laboratory of Biosensing and Molecular Recognition College of Chemistry Frontiers Science Center for New Organic Matter Nankai University Haihe Laboratory of Sustainable Chemical Transformations

Axially chiral phosphines are a class of extremely important ligands in asymmetric catalysis. Herein, an unprecedented copper（I）-catalyzed asymmetric SNAr reaction with HP（S）R2is uncovered, which delivers a series of axially chiral phosphine derivatives in high yields with excellent enantioselectivity. Furthermore, the diastereoselective reaction with the kinetic resolution of racemic HP（S）ArR proceeds smoothly, providing the products with moderate diastereoselectivity and excellent enantioselectivity. Control experiments indicate that HP（S）Ph2is much more active than HPPh2and HP（O）Ph2as the pronucleophile in the present reaction. It is found that the SNAr reaction （the first SNAr） proceeds in a desymmetric manner, providing the desired chiral products while a continued SNAr reaction （the second SNAr） slightly occurs in a kinetic resolution manner in the present catalytic system, which enhances the ee of the desired chiral products. DFTcalculations support a concerted reaction pathway rather than a step-wise mechanism. Finally, axially chiral olefin-phosphines produced by the present method work as suitable ligands in Pdcatalyzed asymmetric allylic substitution with C-, N-, and O-nucleophiles and Rh-catalyzed asymmetric addition of arylboronic acid to benzil.

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