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Assessing the Performance of CMIP6 Models in Simulating Droughts across Global Drylands

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Advances in Atmospheric Sciences 2024年第2期41卷 193-208页

作者： xiaojing YU Lixia ZHANG Tianjun ZHOU Jianghua zheng LASG Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science&TechnologyNanjing 210044China University of Chinese Academy of Sciences Beijing 100049China College of Geography&Remote Sensing Sciences Xinjiang UniversityUrumqi 830046China

Both the attribution of historical change and future projections of droughts rely heavily on climate modeling. However,reasonable drought simulations have remained a challenge, and the related performances of the current state-of-the-art Coupled Model Intercomparison Project phase 6(CMIP6) models remain unknown. Here, both the strengths and weaknesses of CMIP6 models in simulating droughts and corresponding hydrothermal conditions in drylands are assessed.While the general patterns of simulated meteorological elements in drylands resemble the observations, the annual precipitation is overestimated by ~33%(with a model spread of 2.3%–77.2%), along with an underestimation of potential evapotranspiration(PET) by ~32%(17.5%–47.2%). The water deficit condition, measured by the difference between precipitation and PET, is 50%(29.1%–71.7%) weaker than observations. The CMIP6 models show weaknesses in capturing the climate mean drought characteristics in drylands, particularly with the occurrence and duration largely underestimated in the hyperarid Afro-Asian areas. Nonetheless, the drought-associated meteorological anomalies, including reduced precipitation, warmer temperatures, higher evaporative demand, and increased water deficit conditions, are reasonably reproduced. The simulated magnitude of precipitation(water deficit) associated with dryland droughts is overestimated by 28%(24%) compared to observations. The observed increasing trends in drought fractional area,occurrence, and corresponding meteorological anomalies during 1980–2014 are reasonably reproduced. Still, the increase in drought characteristics, associated precipitation and water deficit are obviously underestimated after the late 1990s,especially for mild and moderate droughts, indicative of a weaker response of dryland drought changes to global warming in CMIP6 models. Our results suggest that it is imperative to employ bias correction approaches in drought-related studies over drylands by using CMIP6 outputs.

关键词： droughts hydrothermal conditions drylands CMIP6 model evaluation

Preface: mechanical perturbations induced quench: a challenge of superconductor mechanics

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National Science Review 2023年第3期10卷 7-8页

作者： xiaojing zheng Research Center for Applied Mechanics Xidian University

Superconducting materials have been gradually applied in many areas including energy,transportation,medical imaging and communication.Among them,superconducting magnets that can generate a strong magnetic field above 10 Tesla with absolute advantages of higher quality,lower energy loss,and smaller volume,have become key to the performance improvement of cutting-edge science and large-scale engineering devices such as high-energy accelerators,thermonuclear fusion reactors,

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High-order targeted essentially non-oscillatory scheme for two-fluid plasma model

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Applied Mathematics and Mechanics(English Edition) 2023年第6期44卷 941-960页

作者： Yuhang HOU Ke JIN Yongliang FENG xiaojing zheng School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Institute of Extreme Mechanics Northwestern Polytechnical UniversityXi’an 710072China Shaanxi Key Laboratory of Space Extreme Detection Xi’an 710071China Research Center for Applied Mechanics Xidian UniversityXi’an 710071China

The weakly ionized plasma flows in aerospace are commonly simulated by the single-fluid model,which cannot describe certain nonequilibrium phenomena by finite collisions of particles,decreasing the fidelity of the solution.Based on an alternative formulation of the targeted essentially non-oscillatory(TENO)scheme,a novel high-order numerical scheme is proposed to simulate the two-fluid plasmas problems.The numerical flux is constructed by the TENO interpolation of the solution and its derivatives,instead of being reconstructed from the physical flux.The present scheme is used to solve the two sets of Euler equations coupled with Maxwell's equations.The numerical methods are verified by several classical plasma problems.The results show that compared with the original TENO scheme,the present scheme can suppress the non-physical oscillations and reduce the numerical dissipation.

关键词： plasma high-order scheme targeted essentially non-oscillatory(TENO)scheme two-fluid model

Optimal Strategies Trajectory with Multi-Local-Worlds Graph

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Computers, Materials & Continua 2023年第4期75卷 2079-2099页

作者： Xiang Yu Chonghua Wang xiaojing zheng Chaoyu Zeng Brij BGupta School of Electronics and Information Engineering Taizhou UniversityTaizhouZhejiang318000China China Industrial Control Systems Cyber Emergency Response Team Beijing100040China School of Economics and Management Weifang University of Science and TechnologyShouguangShandong262700China National Computer System Engineering Research Institute of China Beijing102699China Department of Computer Science and Information Engineering Asia UniversityTaiwanTaichung413China Research and Innovation Department Skyline University CollegeSharjahP.O.Box 1797United Arab Emirates Staffordshire University Stoke-on-TrentST42DEUK

This paper constructs a non-cooperative/cooperative stochasticdifferential game model to prove that the optimal strategies trajectory ofagents in a system with a topological configuration of a Multi-Local-Worldgraph would converge into a certain attractor if the system’s configuration isfixed. Due to the economics and management property, almost all systems aredivided into several independent Local-Worlds, and the interaction betweenagents in the system is more complex. The interaction between agents inthe same Local-World is defined as a stochastic differential cooperativegame;conversely, the interaction between agents in different Local-Worldsis defined as a stochastic differential non-cooperative game. We construct anon-cooperative/cooperative stochastic differential game model to describethe interaction between agents. The solutions of the cooperative and noncooperativegames are obtained by invoking corresponding theories, and thena nonlinear operator is constructed to couple these two solutions together.At last, the optimal strategies trajectory of agents in the system is proven toconverge into a certain attractor, which means that strategies trajectory arecertainty as time tends to infinity or a large positive integer. It is concluded thatthe optimal strategy trajectory with a nonlinear operator of cooperative/noncooperativestochastic differential game between agents can make agentsin a certain Local-World coordinate and make the Local-World paymentmaximize, and can make the all Local-Worlds equilibrated;furthermore, theoptimal strategy of the coupled game can converge into a particular attractorthat decides the optimal property.

关键词： Multi-Local-world graph stochastic differential game optimal strategy attractor

New role of platelets in schizophrenia:predicting drug response

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General Psychiatry 2024年第2期37卷 197-206页

作者： Yamin Zhang Yanghao zheng Peiyan Ni Sugai Liang xiaojing Li Hua Yu Wei Wei Xueyu Qi Xueli Yu Rui Xue Liansheng Zhao Wei Deng Qiang Wang Wanjun Guo Tao Li Department of Neurobiology Zhejiang University School of Medicine Affiliated Mental Health Centre&Hangzhou Seventh People's HospitalHangzhouZhejiangChina Liangzhu Laboratory Zhejiang University MOE Frontier Science Center for Brain Science and Brain Machine IntegrationHangzhouZhejiangChina Mental Health Center and Psychiatric Laboratory West China Hospital of Sichuan UniversityChengduSichuanChina

Background Elevated platelet count(PLTc)is associated with first-episode schizophrenia and adverse outcomes in individuals with precursory psychosis.However,the impact of antipsychotic medications on PLTc and its association with symptom improvement remain unclear.Aims We aimed to investigate changes in PLTc levels following antipsychotic treatment and assess whether PLTc can predict antipsychotic responses and metabolic changes after accounting for other related variables.Methods A total of 2985 patients with schizophrenia were randomised into seven groups.Each group received one of seven antipsychotic treatments and was assessed at 2,4 and 6 weeks.Clinical symptoms were evaluated using the positive and negative syndrome scale(PANSS).Additionally,we measured blood cell counts and metabolic parameters,such as blood lipids.Repeated measures analysis of variance was used to examine the effect of antipsychotics on PLTc changes,while structural equation modelling was used to assess the predictive value of PLTc on PANSS changes.Results PLTc significantly increased in patients treated with aripiprazole(F=6.00,p=0.003),ziprasidone(F=7.10,p<0.001)and haloperidol(F=3.59,p=0.029).It exhibited a positive association with white blood cell count and metabolic indicators.Higher baseline PLTc was observed in non-responders,particularly in those defined by the PANSS-negative subscale.In the structural equation model,PLTc,white blood cell count and a latent metabolic variable predicted the rate of change in the PANSS-negative subscale scores.Moreover,higher baseline PLTc was observed in individuals with less metabolic change,although this association was no longer significant after accounting for baseline metabolic values.Conclusions Platelet parameters,specifically PLTc,are influenced by antipsychotic treatment and could potentially elevate the risk of venous thromboembolism in patients with schizophrenia.Elevated PLTc levels and associated factors may impede symptom improvement by promoting inflammation.Given PLTc’s easy measur

关键词： schizophrenia assessed treatment

High-rate CH_(4)-to-C_(2)H_(6) photoconversion enabled by Au/ZnO porous nanosheets under oxygen-free system

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Science China Chemistry 2024年第3期67卷 869-875页

作者： Kai zheng xiaojing Zhang Jun Hu Chengbin Xu Juncheng Zhu Jing Li Mingyu Wu Shan Zhu Li Li Shumin Wang Yumei Lv Xin He Ming Zuo Chengyuan Liu Yang Pan Junfa Zhu Yongfu Sun Yi Xie Hefei National Laboratory for Physical Sciences at Microscale National Synchrotron Radiation LaboratoryUniversity of Science and Technology of ChinaHefei 230026China Key Laboratory of Photochemical Conversion and Optoelectronic Materials Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China State Grid Anhui Electric Power Research Institute Hefei 230601China

Photocatalytic CH_(4) coupling into high-valued C_(2)H_(6) is highly attractive,whereas the photosynthetic rate,especially under oxygen-free system,is still unsatisfying.Here,we designed the negatively charged metal supported on metal oxide nanosheets to activate the inert C-H bond in CH_(4)and hence accelerate CH_(4) coupling performance.As an example,the synthetic Au/ZnO porous nanosheets exhibit the C_(2)H_(6) photosynthetic rate of 1,121.6μmol g^(-1)_(cat)h^(-1)and the CH_(4) conversion rate of 2,374.6μmol g^(-1)_(cat)h^(-1) under oxygen-free system,2 orders of magnitude higher than those of previously reported photocatalysts.By virtue of several in situ spectroscopic techniques,it is established that the generated Au^(δ-)and O^-species together polarized the C-H bond,while the Au^(δ-)and O^-species jointly stabilized the CH_(3) intermediates,which favored the coupling of CH_(3) intermediate to photosynthesize C_(2)H_(6) instead of overoxidation into CO_(x).Thus,the design of dual active species is beneficial for achieving high-efficient CH_(4)-to-C_(2)H_(6) photoconversion.

关键词： dual surface-active sites selective methane coupling ethane room temperature

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Extreme mechanics

Theoretical & Applied Mechanics Letters 2020年第1期10卷 1-7页

作者： xiaojing zheng School of Mechano-Electronic Engineering Xidian UniversityXi'an 710071 China

With the development of cutting-edge sciences and new technologies,we have to consider the size,the density,the hardness,the stiffness and other properties of engineering materials and structures beyond the conventional ranges,as well as their mechanical behavior in extreme environments,such as ultra-conventional temperature,speed,physical and chemical fields,and severe weather,and more effective theories and methods of mechanics are required.This paper first gives the fundamental definition and the scientific connotation of extreme mechanics,then reviews the studies of extreme mechanics from three aspects:the extreme properties,the extreme loads,and the discipline development,as well as major engineering and scientific challenges.The characteristics of extreme mechanics and major challenges in the aspects of mechanical theory,computational methods and experimental techniques are discussed.Prospectivei developments of extreme mechanics are suggested.

关键词： Extreme mechanics Extreme properties Extreme loads Discipline development

Experimental analysis of sand particles' lift-off and incident velocities in wind-blown sand flux

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Acta Mechanica Sinica 2005年第6期21卷 564-573页

作者： Li Xie Zhibao Dong xiaojing zheng Key Laboratory of Mechanics on Western Disaster and Environment Ministry of EducationDepartment of Mechanics Lanzhou UniversityLanzhou Gansu 730000 China Laboratory of Blown Sand Physics and Desert Environments Cold and Arid Regions Environment and EngineeringResearch Institute Chinese Academy of SciencesLanzhou Gansu 730000 China

The probability distributions of sand particles＇ lift-off and incident velocities in a wind-blown sand flux play very important roles in the simulation of the wind-blown sand movement. In this paper, the vertical and the horizontal speeds of sand particles located at 1.0 mm above a sand-bed in a wind-blown sand flux are observed with the aid of Phase Doppler Anemometry （PDA） in a wind tunnel. Based on the experimental data, the probability distributions of not only the vertical lift-off speed but also the lift-off velocity as well as its horizontal component and the incident velocity as well as its vertical and horizontal components can be obtained by the equal distance histogram method. It is found, according to the results of the X^2-test for these probability distributions, that the probability density functions （pdf＇s） of the sand particles＇ lift-off and incident velocities as well as their vertical com- ponents are described by the Gamma density function with different peak values and shapes and the downwind incident and lift-off horizontal speeds, respectively, can be described by the lognormal and the Gamma density functions, These pdf＇s depend on not only the sand particle diameter but also the wind speed.

关键词： Wind-blown sand movement - Tunnel experiment- Incident velocity. Lift-off velocity Probability density

Somatosensory stimulation suppresses the excitability of pyramidal cells in the hippocampal CA1 region in rats

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Neural Regeneration Research 2014年第11期9卷 1138-1144页

作者： Yang Wang Zhouyan Feng Jing Wang xiaojing zheng Key Laboratory of Biomedical Engineering of Education Ministry College of Biomedical Engineering and Instrumentation Science Zhejiang University

The hippocampal region of the brain is important for encoding environment inputs and memory formation. However, the underlying mechanisms are unclear. To investigate the behavior of indi-vidual neurons in response to somatosensory inputs in the hippocampal CA1 region, we recorded and analyzed changes in local ifeld potentials and the ifring rates of individual pyramidal cells and interneurons during tail clamping in urethane-anesthetized rats. We also explored the mechanisms underlying the neuronal responses. Somatosensory stimulation, in the form of tail clamping, chan-ged local ifeld potentials into theta rhythm-dominated waveforms, decreased the spike ifring of py-ramidal cells, and increased interneuron ifring. In addition, somatosensory stimulation attenuated orthodromic-evoked population spikes. These results suggest that somatosensory stimulation sup-presses the excitability of pyramidal cells in the hippocampal CA1 region. Increased inhibition by local interneurons might underlie this effect. These ifndings provide insight into the mechanisms of signal processing in the hippocampus and suggest that sensory stimulation might have thera-peutic potential for brain disorders associated with neuronal hyperexcitability.

关键词： nerve regeneration somatosensory stimulation tail clamping hippocampal CA1 region local field potential unit spike population spike excitability 973 Program neural regeneration