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Science China(Physics,Mechanics & Astronomy) 2024年第1期67卷 106-111页

作者： Yuhang Zhang Cong Liu Xiyu Zhu Hai-Hu Wen center for Superconducting Physics and Materials National Laboratory of Solid State Microstructures and Department of PhysicsNational Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210093China

Recent claim of discovering above-room-temperature superconductivity(Tc≈400 K)at ambient pressure in copper doped apatite Pb10(PO_(4))_(6)O has stimulated world-wide enthusiasm and impulse of motion.A lot of follow-up works have been carried out with controversial *** check whether superconductivity is really present or absent in the material,we need samples which should have a rather pure phase of Pb_(10-x)Cux(PO_(4))_(6)*** we report the characterization results from the Pb_(10-x)Cux(PO_(4))_(6)O with a fraction of about 97 wt.%inferred from the fitting to the X-ray diffraction pattern,if assuming Cu2S as the only *** resistivity measurements show that it is a semiconductor characterized roughly by a ln(1/T)temperature dependence in wide temperature region without trace of *** measurements show that it has a general ferromagnetic signal with a weak superparamagnetic *** grains of the sample show clear interactions with a Nb Fe B *** detected Cu concentration is much lower than the expected nominal *** results show the absence of metallicity and superconductivity in Pb_(10-x)Cux(PO_(4))_(6)O at ambient pressure,and suggest the presence of strong correlation effect.

关键词： superconductivity Pb10(PO4)6O ferromagnetic correlation effect

The importance of data assimilation components for initial conditions and subsequent error growth

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Science China Earth Sciences 2024年第1期67卷 105-116页

作者： Zhongrui WANG Haohao SUN Lili LEI Zhe-Min TAN Yi ZHANG Key Laboratory of Mesoscale Severe Weather Ministry of Educationand School of Atmospheric SciencesNanjing UniversityNanjing 210023China Frontiers Science center for Critical Earth Material Cycling Nanjing UniversityNanjing 210023China

Despite a specific data assimilation method,data assimilation(DA)in general can be decomposed into components of the prior information,observation forward operator that is given by the observation type,observation error covariances,and background error *** a classic Lorenz model,the influences of the DA components on the initial conditions(ICs)and subsequent forecasts are systematically investigated,which could provide a theoretical basis for the design of DA for different scales of *** forecast errors undergo three typical stages:a slow growth stage from 0 h to 5 d,a fast growth stage from 5 d to around 15 d with significantly different error growth rates for ensemble and deterministic forecasts,and a saturation stage after 15 *** strategies that provide more accurate ICs can improve the *** assimilation is superior to offline assimilation,and a flow-dependent background error covariance matrix(Pf)provides better analyses than a static background error covariance matrix(B)for instantaneous observations and frequent time-averaged observations;but the opposite is true for infrequent time-averaged observations,since cycling simulation cannot construct informative priors when the model lacks predictive skills and the flow-dependent Pf cannot effectively extract information from low-informative observations as the static *** observations contain more information than time-averaged observations,thus the former is preferred,especially for infrequent observing ***,ensemble forecasts have advantages over deterministic forecasts,and the advantages are enlarged with less informative observations and lower predictive-skill model priors.

关键词： Data assimilation Atmospheric predictability Background error covariances Ensemble forecasts

Dielectric anisotropy in liquid crystal mixtures with nematic and smectic phases

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Chinese Physics B 2024年第8期33卷 519-524页

作者：汤星舟叶家耀王子烨姜皓译尚小虎杨朝雁李炳祥 nanjing University of Posts and Telecommunications College of Electronic and Optical Engineering&College of Flexible Electronics(Future Technology)Nanjing 210023China National Laboratory of Solid State Microstructures College of Engineering and Applied SciencesNanjing UniversityNanjing 210023China

The modulation of dielectric anisotropy(△ε)is pivotal for elucidating molecular interactions and directing the alignment of liquid *** this study,we combine liquid crystals with opposing dielectric anisotropies to explore the impact of varying concentrations on their *** report the sign-reversal of△εin both the nematic and smectic A phases of these mixed liquid crystals,alongside a dual-frequency behaviour across a broad temperature *** research further quantifies the influence of mixture ratios under various temperatures and electric field *** exploration may pave the way for the discovery of new physical phenomena.

关键词： mixed liquid crystal dielectric anisotropy tunable nematic smectic

PERIODIC SYSTEMS WITH TIME DEPENDENT MAXIMAL MONOTONE OPERATORS

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Acta Mathematica Scientia 2024年第4期44卷 1280-1300页

作者： Zhenhai LIU Nikolaos S.PAPAGEORGIOU center for applied mathematics of Guangri Yulin Normal UniversityYulin 537000China Guangri Key Laboratory of Universities Optimization Control and Engineering Calculation College of Mathematics and PhysicsGuangri Minzu UniversityNanning 530006China Department of mathematics National Technical UniversityZografou Campus15780 AthensGreece

We consider a first order periodic system in R^(N),involving a time dependent maximal monotone operator which need not have a full domain and a multivalued *** prove the existence theorems for both the convex and nonconvex *** also show the existence of extremal periodic solutions and provide a strong relaxation ***,we provide an application to nonlinear periodic control systems.

关键词： periodic boundary condition time-dependent maximal monotone operator convex and nonconvex problems extremal solutions strong relaxation

Studies on the motion and radiation of interior plasmas in gas-filled hohlraums with different laser entrance hole sizes

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Plasma Science and Technology 2024年第7期26卷 40-47页

作者：郭亮李欣李琦李三伟胡昕李晋邓博邓克立王强强曹柱荣侯立飞车兴森杜华冰徐涛何小安李志超蒋小华蒋炜郑春阳郑无敌宋鹏丁永坤杨冬杨家敏 Research center of Laser Fusion China Academy of Engineering PhysicsMianyang 621900People’s Republic of China Institute of applied Physics and Computational mathematics Beijing 100088People’s Republic of China

An experiment on 100 k J laser facility is performed to study the motive features and radiation properties of plasmas from different areas inside gas-filled cylindrical *** hohlraums are designed to possess one open end and one laser entrance hole(LEH)with different diameters,which would or not result in the blocking of the *** x-ray streak camera that is set at 16 degrees with respect to the hohlraum axis is applied to acquire the timeresolved x-ray images from the open *** on the images,we can study the evolutions of the wall plasma,corona bubble plasma and LEH plasma simultaneously through an equivalent view field of hohlraum ***-group flat response x-ray detectors are applied to measure the x-ray *** order to understand these characteristics,our two-dimensional radiation hydrodynamic code is used to simulate the experimental *** the accuracy of reproduction,dielectronic recombination and two parameter corrections are applied in our *** on the comparison between experiments and simulations,we quantitatively understand the blocking process of LEH and the motion effects of other *** calibrated code is beneficial to design the gas-filled hohlraum in a nearby parameter space,especially the limit size of LEH.

关键词： gas-filled hohlraum plasma expansion LEH blocking

A probabilistic model based on the peak-over-threshold approach for risk assessment of airport controllers’performance

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Journal of Safety Science and Resilience 2024年第1期5卷 110-118页

作者： Lili Zu Yijie Lu Min Dong College of Economics and Management Nanjing University of Aeronautics and AstronauticsNanjing 211106China School of Engineering and applied Science George Washington UniversityWashington DC 20052USA College of Civil Aviation Nanjing University of Aeronautics and AstronauticsNanjing 211106China

Airport tower control plays an instrumental role in ensuring airport ***,obtaining objective,quantitative safety evaluations is challenging due to the unavailability of pertinent human operation *** study introduces a probabilistic model that combines aircraft dynamics and the peak-over-threshold(POT)approach to assess the safety performance of airport *** applied the POT approach to model reaction times extracted from a radiotelephony dataset via a voice event detection *** model couples the risks of tower control and aircraft operation to analyze the influence of human *** data from radiotele-phony communications and the Base of Aircraft Data(BADA)database,we compared risk levels across *** findings revealed heightened airport control risks under low demand(0.374)compared to typical conditions(0.197).Furthermore,the risks associated with coupling under low demand exceeded those under typical de-mand,with the final approach stage presenting the highest risk(4.929×107).Our model underscores the significance of human factors and the implications of mental disconnects between pilots and controllers for safety ***,these consistent findings affirm the reliability of our probabilistic model as an evaluative tool for evaluating the safety performance of airport tower *** results also illuminate the path toward quantitative real-time safety evaluations for airport controllers within the *** recommend that airport regulators focus on the performance of airport controllers,particularly during the final approach stage.

关键词： Safety evaluation Performance Probabilistic model Task demand Airport controller

Alleviating limit cycling in training GANs with an optimization technique

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Science China mathematics 2024年第6期67卷 1287-1316页

作者： Keke Li Liping Tang Xinmin Yang National center for applied mathematics in Chongqing Chongqing Normal UniversityChongqing401331China School of Mathematical Sciences University of Electronic Science and Technology of ChinaChengdu611731China

In this paper,we undertake further investigation to alleviate the issue of limit cycling behavior in training generative adversarial networks(GANs)through the proposed predictive centripetal acceleration algorithm(PCAA).Specifically,we first derive the upper and lower complexity bounds of PCAA for a general bilinear game,with the last-iterate convergence rate notably improving upon previous ***,we combine PCAA with the adaptive moment estimation algorithm(Adam)to propose PCAA-Adam,for practical training of GANs to enhance their generalization ***,we validate the effectiveness of the proposed algorithm through experiments conducted on bilinear games,multivariate Gaussian distributions,and the CelebA dataset,respectively.

关键词： GANs general bilinear game predictive centripetal acceleration algorithm lower and upper complexity bounds PCAA-Adam

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Tamping the movement of the laser absorption cutoff position using gold foam hohlraum

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Plasma Science and Technology 2024年第5期26卷 56-61页

作者：张璐李丽灵林稚伟董云松景龙飞郑建华况龙钰黎航郑金华张继彦宋天明张志宇赵阳牛高杨冬杨家敏丁永坤 Research center of Laser Fusion China Academy of Engineering PhysicsMianyang 621900People’s Republic of China Institute of applied Physics and Computational mathematics Beijing 100088People’s Republic of China

In indirect-driven laser fusion experiments,the movement of the laser absorption layer will distort the radiation uniformity on the *** gold foam has advantages in symmetry control and lowering wall plasma blowoff when used in an inertial confinement fusion(ICF)*** work investigates the motion of the laser absorption cutoff position using lowdensity foam gold *** is found that the motion of the laser absorption cutoff position can be significantly mitigated through optimal initial low density,tailored to a specific laser *** a short square laser pulse,the laser absorption cutoff position remains almost stationary at an initial density of approximately 0.6 g cm^(-3).For a long-shaped laser pulse,the minimal motion of the laser absorption cutoff position is observed at an initial density of about 0.1 g cm^(-3).This approach allows for the adjustment of the symmetry of the hohlraum radiation *** insights gained from this study serve as a crucial reference for optimizing the hohlraum wall density.

关键词： hohlraum symmetry laser absorption plasma blowoff gold foam

Individual dynamics and local heterogeneity provide a microscopic view of the epidemic spreading

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Chinese Physics B 2024年第5期33卷 656-663页

作者：朱友源沈瑞哲董昊王炜 Kuang Yaming Honors School Nanjing UniversityNanjing 210023China Collaborative Innovation center of Advanced Microstructures National Laboratory of Solid State MicrostructureSchool of PhysicsNanjing UniversityNanjing 210093China Institute for Brain Sciences Nanjing UniversityNanjing 210023China State Key Laboratory of Analytical Chemistry for Life Science Nanjing UniversityNanjing 210023China

The COVID-19 pandemic has caused severe global disasters,highlighting the importance of understanding the details and trends of epidemic transmission in order to introduce efficient intervention *** the widely used deterministic compartmental models have qualitatively presented continuous “analytical” insight and captured some transmission features,their treatment usually lacks spatiotemporal ***,we propose a stochastic individual dynamical(SID)model to mimic the random and heterogeneous nature of epidemic *** SID model provides a unifying framework for representing the spatiotemporal variations of epidemic development by tracking the movements of each *** this model,we reproduce the infection curves for COVID-19 cases in different areas globally and find the local dynamics and heterogeneity at the individual level that affect the disease *** macroscopic trend of virus spreading is clearly illustrated from the microscopic perspective,enabling a quantitative assessment of different ***,this model is also applicable to studying stochastic processes at the “meter scale”,e.g.,human society’s collective dynamics.

关键词： Brownian motion epidemic spreading heterogeneity

Nonreciprocal Photon Blockade Based on Zeeman Splittings Induced by a Fictitious Magnetic Field

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Chinese Physics Letters 2024年第7期41卷 36-46页

作者：苏欣金飚兵唐江山夏可宇 College of Engineering and applied Sciences National Laboratory of Solid State Microstructuresand Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210023China Research Institute of Superconductor Electronics(RISE)&Key Laboratory of Optoelectronic Devices and Systems with Extreme Performances of MOE School of Electronic Science and EngineeringNanjing UniversityNanjing 210023China

Quantum nonreciprocity, such as nonreciprocal photon blockade, has attracted a great deal of attention due to its unique applications in quantum information processing. Its implementation primarily relies on rotating nonlinear systems, based on the Sagnac effect. Here, we propose an all-optical approach to achieve nonreciprocal photon blockade in an on-chip microring resonator coupled to a V-type Rb atom, which arises from the Zeeman splittings of the atomic hyperfine sublevels induced by the fictitious magnetic field of a circularly polarized control laser. The system manifests single-photon blockade or multi-photon tunneling when driven from opposite directions. This nonreciprocity results from the directional detunings between the countercirculating probe fields and the V-type atom, which does not require the mechanical rotation and facilitates integration. Our work opens up a new route to achieve on-chip integrable quantum nonreciprocity, enabling applications in chiral quantum technologies.

关键词： effect reciprocal quantum