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Quantum phase transition of the Jaynes-Cummings model

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Science China(Physics,Mechanics & Astronomy) 2024年第1期67卷 1-9页

作者： Cheng liu jin-Feng Huang Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Key Laboratory for Matter Microstructure and Function of Hunan ProvinceDepartment of Physics and Synergetic Innovation Center for Quantum Effects and ApplicationsInstitute of Interdisciplinary StudiesHunan Normal UniversityChangsha 410081China

Herein,we propose an experimentally feasible scheme to show the quantum phase transition of the Jaynes-Cummings(JC)model by modulating the transition frequency of a two-level system in a quantum Rabi model with strong *** tuning the modulation frequency and amplitude,the ratio of the effective coupling strength of the rotating terms to the effective cavity(atomic transition)frequency can enter the deep-strong coupling regime,while the counter-rotating terms can be ***,a deep-strong JC model is *** ratio of the coupling strength to resonance frequencies in the deep-strong JC model is two orders of magnitude larger than the corresponding ratio in the original quantum Rabi *** scheme can be employed in atom-cavity resonance and off-resonance cases,and it is valid over a broad *** nonzero average cavity photons of the ground state indicate the emergence of a quantum phase ***,we demonstrate the dependence of the phase diagram on the atom-cavity detuning and modulation *** the parameters used in our scheme are within the reach of current experimental *** scheme provides a new mechanism for investigating the critical phenomena of finite-sized systems without requiring classical field limits,thereby opening a door for studying fundamental quantum phenomena occurring in the ultrastrong and even deep-strong coupling regimes.

关键词： Jaynes-Cummings model quantum phase transition frequency modulation

Effects of tree size and organ age on variations in carbon,nitrogen,and phosphorus stoichiometry in Pinus koraiensis

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Journal of Forestry Research 2024年第3期35卷 155-165页

作者： Yanjun Wang Guangze jin Zhili liu Center for Ecological Research Northeast Forestry UniversityHarbin 150040People's Republic of China Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education Northeast Forestry UniversityHarbin 150040People's Republic of China Northeast Asia Biodiversity Research Center Northeast Forestry UniversityHarbin 150040People's Republic of China

Carbon(C),nitrogen(N),and phosphorus(P)are of fundamental importance for growth and nutrient dynamics within plant organs and deserve more attention at regional to global ***,our knowledge of how these nutrients vary with tree size,organ age,or root order at the individual level remains *** determined C,N,and P contents and their stoichiometric ratios(i.e.,nutrient traits)in needles,branches,and fine roots at different organ ages(0-3-year-old needles and branches)and root orders(1st-4th order roots)from 64 Pinus koraiensis of varying size(Diameter at breast height ranged from 0.3 to 100 cm)in northeast *** factors were also *** results show that nutrient traits were regulated by tree size,organ age,or root order rather than soil *** a whole-plant level,nutrient traits decreased in needles and fine roots but increased in branches with tree *** the organ level,age or root order had a negative effect on C,N,and P and a positive effect on stoichiometric *** results demonstrate that nutrient variations are closely related to organ-specific functions and ecophysiological processes at an individual *** is suggested that the nutrient acquisition strategy by younger trees and organ fractions with higher nutrient content is for ***,nutrient storage strategy in older trees and organ fractions are mainly for steady *** results clarified the nutrient utilization strategies during tree and organ ontogeny and suggest that tree size and organ age or root order should be simultaneously considered to understand the complexities of nutrient variations.

关键词： Tree size Organ age(or root order) Carbon(C) Nitrogen(N) Phosphorus(P) Pinus koraiensis

Pb induced dislocation defects of PtCo systems: Strain-triggered oxygen reduction reaction for PEMFC

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Nano Research 2024年第4期17卷 2462-2472页

作者： Chun jin Qiheng Wang jingjun liu Beijing Key Laboratory of Electrochemical Process and Technology for Materials Beijing 100029China Beijing University of Chemical Technology Beijing 100029China

Design and development of advanced electrocatalysts with high performance and low Pt consumption are crucial for reducing the kinetic energy barrier of the cathode oxygen reduction reaction(ORR)and improving the efficiency of proton exchange membrane fuel cells(PEMFC).In this study,we demonstrate a Pb-modulated PtCo system for efficient ORR,in which the inclusion of Pb in ternary alloys induces dislocation defects due to the significant difference in atomic ***-PtCoPb was confirmed to exhibit significantly higher ORR activity and stability in acidic *** practical PEMFC applications,it outperforms the corresponding commercial Pt/C with a mass activity of 0.58 A·mgPt^(-1),making it a promising alternative to state-of-the-art Pt-based *** combination of experimental results and density functional theory(DFT)calculations offers valuable atomic-level insights into the dislocation *** with a larger atomic radius is located in the lattice stretching region below the dislocation slip plane,forming a structure similar to a Cottrell atmosphere,which reduces the dislocation energy and puts the system in a lower energy *** Cottrell atmosphere pins the dislocation structure and stabilizes the ternary *** adjusting the amount of added Pb,a moderate level of dislocation density induces a tuned strain effect,thereby enhancing the electrocatalytic mechanism by optimizing the electronic structure of the alloy surface and the adsorption and desorption of oxygen *** work provides valuable insights into the design and development of lattice dislocation defect structures to trigger strain effects for improving ORR performance.

关键词： dislocation defect strain effect Pb-modulated oxygen reduction reaction

The twisted conical Kahler-Ricci solitons on Fano manifolds

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Science China Mathematics 2024年第5期67卷 1085-1102页

作者： Xishen jin Jiawei liu School of Mathematics Renmin University of ChinaBeijing 100872China School of Mathematics and Statistics Nanjing University of Science&TechnologyNanjing 210094China

In this paper,we show the relation between the existence of twisted conical K?hler-Ricci solitons and the greatest log Bakry-Emery-Ricci lower bound on Fano *** is based on our proofs of some openness theorems on the existence of twisted conical Kahler-Ricci solitons,which generalize Donaldson’s existence conjecture and the openness theorem of the conical K?hler-Einstein metrics to the conical soliton case.

关键词： greatest log Bakry-Emery-Ricci lower bound twisted conical Kahler-Ricci soliton twisted Kahler-Ricci soliton

Adaptive neural network control of a 2-DOF helicopter system considering input constraints and global prescribed performance

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Science China(Information Sciences) 2024年第7期67卷 224-239页

作者： Zhijia ZHAO Jiale WU Zhijie liu we HE C.L.Philip CHEN School of Mechanical and Electrical Engineering Guangzhou University School of Intelligence Science and Technology and Key Laboratory of Intelligent Bionic Unmanned Systems of Ministry of Education University of Science and Technology Beijing School of Computer Science and Engineering South China University of Technology Pazhou Lab

In this study, an adaptive neural network(NN) control is proposed for nonlinear two-degree-offreedom(2-DOF) helicopter systems considering the input constraints and global prescribed ***, radial basis function NN(RBFNN) is employed to estimate the unknown dynamics of the helicopter system. Second, a smooth nonaffine function is exploited to approximate and address nonlinear constraint functions. Subsequently, a new prescribed function is proposed, and an original constrained error is transformed into an equivalent unconstrained error using the error transformation and barrier function transformation methods. The analysis of the established Lyapunov function proves that the controlled system is globally uniformly bounded. Finally, the simulation and experimental results on a constructed Quanser's test platform verify the rationality and feasibility of the proposed control.

关键词： adaptive NN control 2-DOF helicopter global prescribed performance input constraints

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Regulation of interlayer channels of graphene oxide nanosheets in ultra-thin Pebax mixed-matrix membranes for CO_(2) capture

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Chinese Journal of Chemical Engineering 2024年第3期67卷 257-267页

作者： Feifan Yang Yuanhang jin Jiangying liu Haipeng Zhu Rong Xu Fenjuan Xiangli Gongping liu Wanqin jin State Key Laboratory of Materials-Oriented Chemical Engineering College of Chemical EngineeringNanjing Tech UniversityNanjing 211816China Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology School of Petrochemical EngineeringChangzhou UniversityChangzhou 213164China Shandong Production and Research Long Membrane Technology Development Co. Ltd.Yantai Economic Development ZoneYantai 265505China

For the application of carbon capture by membrane process,it is crucial to develop a highly permeable CO_(2)-selective *** this work,we reported an ultra-thin polyether-block-amide(Pebax)mixedmatrix membranes(MMMs)incorporated by graphene oxide(GO),in which the interlayer channels were regulated to optimize the CO_(2)/N_(2) separation *** membrane preparation conditions were systematically investigated on the influence of the membrane structure and separation performance,including the lateral size of GO nanosheets,GO loading,thermal reduction temperature,and *** results demonstrated that the precisely regulated interlayer channel of GO nanosheets can rapidly provide CO_(2)-selective transport channels due to the synergetic effects of size sieving and preferential *** GO/Pebax ultra-thin MMMs exhibited CO_(2)/N_(2) selectivity of 72 and CO_(2) permeance of 400 GPU(1 GPU=106 cm^(3)(STP)·cm^(2)·s^(-1)·cmHg^(-1)),providing a promising candidate for CO_(2) capture.

关键词： Mixed-matrix membrane Ultra-thin membrane Pebax Graphene oxide CO_(2) capture

Peeling of Magneto-responsive Beams with Large Deformation Mediated by the Parallel Magnetic Field

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Acta Mechanica Solida Sinica 2024年第3期37卷 457-467页

作者： Gongqi Cao Zhangna Xue Shiyang liu Yuchen jin Jianlin liu College of Pipeline and Civil Engineering China University of Petroleum(East China)Qingdao266580China

Elasto-capillarity phenomena are prevalent in various industrial fields such as mechanical engineering,material science,aerospace,soft robotics,and *** this study,two typical peeling processes of slender beams driven by the parallel magnetic field are investigated based on experimental and theoretical *** first is the adhesion of two parallel beams,and the second is the self-folding of a long *** these two cases,the energy variation method on the elastica is used,and then,the governing equations and transversality boundary conditions are *** is shown that the analytical solutions are in excellent agreement with the experimental *** effects of magnetic induction intensity,distance,and surface tension on the deflection curve and peeling length of the elastica are fully *** results are instrumental in accurately regulating elasto-capillarity in structures and provide insights for the engineering design of programmable microstructures on surfaces,microsensors,and bionic robots.

关键词： Magneto-responsive beam Adhesion and peeling Self-folding Elastica Transversality condition

Recent progress on nanomaterial-based electrochemical dissolved oxygen sensors

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Chinese Journal of Chemical Engineering 2024年第4期68卷 103-119页

作者： Shaoqi Zhang Tao liu Zhenyu Chu Wanqin jin State Key Laboratory of Materials-Oriented Chemical Engineering College of Chemical EngineeringNanjing Tech UniversityNanjing 211816China

Dissolved oxygen(DO)usually refers to the amount of oxygen dissolved in *** the environment,medicine,and fermentation industries,the DO level needs to be accurate and capable of online monitoring to guide the precise control of water quality,clinical treatment,and microbial *** with other analytical methods,the electrochemical strategy is superior in its fast response,low cost,high sensitivity,and portable ***,an electrochemical DO sensor faces a trade-off between sensitivity and long-term stability,which strongly limits its practical *** solve this problem,various advanced nanomaterials have been proposed to promote detection performance owing to their excellent electrocatalysis,conductivity,and chemical ***,in this review,we focus on the recent progress of advanced nanomaterial-based electrochemical DO *** the comparison of the working principles on the main analysis techniques toward DO,the advantages of the electrochemical method are *** is placed on recently developed nanomaterials that exhibit special characteristics,including nanostructures and preparation routes,to benefit DO ***,we also introduce some interesting research on the configuration design of the electrode and device,which is rarely ***,the different requirements of the electrochemical DO sensors in different application fields are included to provide brief guidance on the selection of appropriate ***,the main challenges are evaluated to propose future development prospects and detection strategies for nanomaterial-based electrochemical sensors.

关键词： Nanomaterial Dissolved oxygen Electrochemical sensor Nanostructures Detection principles

Optimization of Fixture Number in Large Thin-Walled Parts Assembly Based on IPSO

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 213-227页

作者： Changhui liu jing Wang Ying Zheng Ke jin Jianbo Yu Jianfeng liu School of Mechanical Engineering Tongji UniversityShanghai 201804China Shanghai Jiaotong University Shanghai 200240China Shanghai Waigaoqiao Shipbuilding Co. Ltd.Shanghai 200137China

There are lots of researches on fixture layout optimization for large thin-walled *** researches focus on the positioning problem,i.e.,optimizing the positions of a constant number of ***,how to determine the number of fixtures is *** most cases,the number of fixtures located on large thin-walled parts is determined based on engineering experience,which leads to huge fixture number and extra ***,this paper constructs an optimization model to minimize the number of *** constraints are set in the optimization model to ensure that the part deformation is within the surface profile *** addition,the assembly gap between two parts is also *** conduct the optimization,this paper develops an improved particle swarm optimization(IPSO)algorithm by integrating the shrinkage factor and adaptive inertia *** the algorithm,particles are encoded according to the fixture *** dimension of the particle is assigned to a sub-region by constraining the optional position range of each fixture to improve the optimization ***,a case study on ship curved panel assembly is provided to prove that our method can optimize the number of fixtures while meeting the assembly quality *** research proposes a method to optimize the number of fixtures,which can reduce the number of fixtures and achieve deformation control at the same time.

关键词： Assembly quality Large thin-walled parts Fixture layout PSO FEM