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Acta Geologica Sinica(English Edition) 2012年第4期86卷 949-962页

作者： SHAO Longyi WANG Hao YU Xiaohui LU Jing ZHANG Mingquan State key laboratory of Coal Resources and Safe Mining and School of Geosciences and Survey EngineeringChina University of Mining and Technology Institute of disaster Prevention Coal Geology and Prospecting Institute of Yunnan province

Inertinite maceral compositions of the Late Permian coals from three sections in the terrestrial and paralic settings of eastern Yunnan are analyzed in order to reveal the paleo-fire events and the atmospheric oxygen levels in the latest Permian. Although the macerals in the studied sections are generally dominated by vitrinite, the inertinite group makes up a considerable proportion. Its content increases upward from the beginning of the Late Permian to the coal seam near the Permian- Triassic boundary. Based on the microscopic features and the prevailing theory that inertinite is largely a by-product of paleo-fires, we suggest that the increasing upward trend of the inertinite abundance in the latest Permian could imply that the Late Permian peatland had suffered from frequent wildfires. Since ignition and burning depend on sufficient oxygen, a model-based calculation suggests that the 02 levels near the Wuchiapingian/Changhsingian boundary and the Permian-Triassic boundary are 27% and 28% respectively. This output adds supports to other discoveries made in the temporal marine and terrestrial sediments, and challenges the theories advocating hypoxia as a mechanism for the PermianTriassic boundary crisis.

关键词： coal maceral inertinite paleo-atmospheric oxygen level wildfire Permian-Triassic boundary

Rock-magnetic characteristics and mechanisms of the Titel loess-paleosol sequence in northern Serbia since late Middle Pleistocene

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Science China Earth Sciences 2022年第3期65卷 503-517页

作者： Zhi LIU Xiuming LIU Slobodan B.MARKOVIC Bin LU Ruina HE College of Geography and Environment Baoji University of Arts and SciencesBaoji 721013China key laboratory of disaster Monitoring and mechanism simulation of shaanxi province Baoji 721013China School of Geographical Sciences Fujian Normal UniversityFuzhou 350007China Department of Earth and Environmental Sciences Macquarie UniversitySydneyNSW 2109Australia Chair of Physical Geography Faculty of SciencesUniversity of Novi SadTrg Dositeja Obradovica 321000 Novi SadSerbia

The changing pattern of magnetic characteristics in eastern European loess deposits is the most similar across the world to that of the Chinese Loess Plateau,both of which are dominated by the strength of *** a systematical study to the rock magnetism of eastern European loess is not only helpful for understanding the paleoclimatic information preserved by themselves,but also beneficial for promoting the cognition of the pedogenic mechanism in loess *** this study,a detailed rock-magnetic analysis of seventy loess/paleosol samples,taken from the Titel Loess Plateau in northern Serbia,is carried out for a better understanding of the magnetic records since late Middle *** results provide us some ***,the magnetic susceptibility values of the paleosols in the Titel loess-paleosol sequence are generally less than 100×10^(-8)m^(3)kg^(-1),significantly lower than those of the loess sections in the Chinese Loess Plateau,even though they are under similar climatic ***,the behaviors of the parameters related to the distributions of magnetic particles in these two regions are *** difference in the contents of ferrimagnetic minerals is the leading reason that caused the difference in their magnetic characteristics,but the mechanism is still open to ***,based on the analysis of thermomagnetic curves,a gradually increasing trend of the relative contents of maghemite over the last four glacial-interglacial cycles is *** realization of thermally unstable maghemite from Chinese loess leads us to speculate that the long-term increasing trend of the relative contents of maghemite in Titel loess-paleosol sequence likely is a mineralogical response to the progressive enhancement of continental climate in the Pannonian Basin since the Middle Pleistocene.

关键词： Eastern European loess Magnetic susceptibility Pedogenesis Environmental magnetism Paleoclimate

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3D simulation of Flow with Free Surface Based on Adaptive Octree Mesh System

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Transactions of Tianjin University 2015年第1期21卷 32-40页

作者：李绍武庄茜黄筱云王东 State key laboratory of Hydraulic Engineering simulation and Safety Tianjin University key laboratory of Water-Sediment Science and Water disaster Prevention of Hunan province Changsha University of Science and Technology School of Civil Engineering Tianjin Chengjian University

The technique of adaptive tree mesh is an effective way to reduce computational cost through automatic adjustment of cell size according to necessity. In the present study, the 2D numerical N-S solver based on the adaptive quadtree mesh system was extended to a 3D one, in which a spatially adaptive oetree mesh system and multiple particle level set method were adopted for the convenience to deal with the air-water-structure multiple-medium coexisting domain. The stretching process of a dumbbell was simulated and the results indicate that the meshes are well adaptable to the free surface. The collapsing process of water column impinging a circle cylinder was simulated and from the results, it can be seen that the processes of fluid splitting and merging are properly simulated. The interaction of second-order Stokes waves with a square cylinder was simulated and the obtained drag force is consistent with the result by the Morison＇s wave force formula with the coefficient values of the stable drag component and the inertial force component bein~ set as 2.54.

关键词： adaptive octree mesh 3D numerical flume spatially adaptive multiple particle level set

Vertical distribution of aerosol optical properties based on aircraft measurements over the Loess Plateau in China

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Journal of Environmental Sciences 2015年第8期27卷 44-56页

作者： Junxia Li Xingang Liu Liang Yuan Yan Yin Zhanqing Li Peiren Li Gang Ren Lijun Jin Runjun Li Zipeng Dong Yiyu Li Junmei Yang Weather Modification Office of Shanxi province key laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration Nanjing University of Information Science and Technology State key laboratory of Water Environment simulation School of Environment Beijing Normal University College of Global Change and Earth System Science Beijing Normal University Meteorological Institute of shaanxi province

Vertical distributions of aerosol optical properties based on aircraft measurements over the Loess Plateau were measured for the first time during a summertime aircraft campaign, 2013 in Shanxi, China. Data from four flights were analyzed. The vertical distributions of aerosol optical properties including aerosol scattering coefficients（σsc）, absorption coefficients（σab）,Angstr？m exponent（α）, single scattering albedo（ω）, backscattering ratio（βsc）, aerosol mass scattering proficiency（Q sc） and aerosol surface scattering proficiency（Q sc′） were obtained. The mean statistical values of σsc were 77.45 Mm-1（at 450 nm）, 50.72 Mm-1（at 550 nm）, and32.02 Mm-1（at 700 nm）. The mean value of σab was 7.62 Mm-1（at 550 nm）. The mean values ofα, βsc and ω were 1.93, 0.15, and 0.91, respectively. Aerosol concentration decreased with altitude. Most effective diameters（ED） of aerosols were less than 0.8 μm. The vertical profiles of σsc,, α, βsc, Q sc and Q sc′ showed that the aerosol scattering properties at lower levels contributed the most to the total aerosol radiative forcing. Both α and βsc had relatively large values, suggesting that most aerosols in the observational region were small particles. The mean values of σsc, α, βsc, Q sc, Q sc′, σab and ω at different height ranges showed that most of the parameters decreased with altitude. The forty-eight hour backward trajectories of air masses during the observation days indicated that the majority of aerosols in the lower level contributed the most to the total aerosol loading, and most of these particles originated from local or regional pollution emissions.

关键词： Vertical distribution Optical properties Aircraft measurements The Loess Plateau

Theoretical Investigation on the Charge Transport Properties of 2,5-Di(cyanovinyl)-thiophene/furan with the Kinetic Monte Carlo Method

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Chinese Journal of Structural Chemistry 2016年第5期35卷 687-697页

作者：赵蔡斌葛红光靳玲侠张强尹世伟 School of Chemical and Environmental Science Shaanxi University of Technology key laboratory for Macromolecular Science of shaanxi province School of Chemistry and Chemical Engineering Shaanxi Normal University

Exploring, designing, and synthesizing novel organic field-effect transistor （OFET） materials have kept an important and hot issue in organic electronics. In the current work, the charge transport properties for 2,5-di（cyanovinyl）thiophene/furan crystal associating two pentafluorophenyl units linked via the azomethine bond, CTE and CFE have been theoretically investigated by means of density functional theory （DFT） calculations coupled with the incoherent charge-hopping mechanism and the kinetic Monte Carlo simulation. Results show that these two compounds possess remarkably low-lying HOMO （-7.0 eV） and LUMO （-4.0 eV） levels, as well as large electron affinities （〉 3.0 eV）, which indicate their high stability exposed to air as promising OFET materials. However, the ph value at room temperature （T = 300 K） is predicted to be 2.058x10^7 cm26Vl·s-1, and the is as low as 9.834^10-8 cm2-V-l.s-1 for CFT crystal. Meanwhile, these two values are 7.561 x 10-8 and 8.437 x 10-8 cm2.V-I.s-1 for the CFE crystal, respectively. Furthermore, the simulation of angle-dependent mobility in the a-b, a-c, and b-c crystal planes shows that the charge transport in CTE and CFE crystals is remarkably anisotropic, which maybe is helpful for the fabrication of high-performance OFET devices.

关键词： charge transport, density functional theory, theoretical investigation

Catastrophe Risk Management for Electric Power Distribution Systems:An Insurance Approach

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CSEE Journal of Power and Energy Systems 2023年第1期9卷 393-410页

作者： Siyuan Sun Gengfeng Li Yiheng Bian Zhaohong Bie Qianwen Hu State key laboratory of Electrical Insulation and Power Equipment Smart Grid Key Laboratory of Shaanxi ProvinceDepartment of Electrical EngineeringXi’an Jiaotong UniversityXi’an 710049China

High-impact,low-probability catastrophes may cause equipment damage,customer outages and serious economic losses to an aging power distribution infrastructure with low redundancy and *** cope with catastrophe risks faced by distribution systems(DSs),insurance is proposed as a supplement to existing resilience enhancement measures,which can provide financial aid in recovery after disasters,as well as incentives to make DSs more resilient to potential *** calls for a quantitative assessment for insurance pricing that can not only predict potential losses caused by future catastrophes but also evaluate the effect of risk management *** this paper,a four-module actuarial framework,including hazard,vulnerability,resilience,and insurance modules,is developed to assess the catastrophe risks of *** on Monte Carlo simulation(MCS)and mixed integer linear programming(MILP),the dynamic characteristics of disasters,random failures of equipment,control measures including fault isolation,load transfer,line patrolling,manual switching,and fault repair,are comprehensively incorporated in the premium determination of catastrophe *** simulations are performed on the modified IEEE 33-bus test systems to illustrate the validity of the proposed catastrophe insurance schemes.

关键词： Actuarial framework catastrophe insurance distribution system risk assessment

Experimental and numerical investigations of the aerodynamic noise reduction of automotive side view mirrors

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Journal of Hydrodynamics 2018年第4期30卷 642-650页

作者：陈鑫汪硕吴元强李延洋王怀玉 State key laboratory of Automobile simulation and Control Jilin University

This paper studies the aeroacoustics of the side view mirrors by wind tunnel tests and numerical simulations. The mirror is placed on a table in the wind tunnel test. Based on the experiment results, a numerical analysis model is established to analyze the acoustic field in the wake of the side view mirror by the Large Eddy simulation（LES）. The flow field and the noise level of two different side view mirrors are compared in the simulation. It is shown that, with the serration structures applied onto the mirror surface, the turbulence zone and the pressure fluctuation in the wake of the bionic model are improved effectively, which helps its flow control and noise reduction. Meanwhile, as is shown in the noise spectra, when the noise frequency is over 500 Hz, for the bionic mode, the noise is reduced to a lower level than with the original one, which further shows its effectiveness in the noise reduction.

关键词： Aerodynamic noise side view mirror flow field acoustic field bionic noise reduction

O(1/t) complexity analysis of the generalized alternating direction method of multipliers

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Science China Mathematics 2019年第4期62卷 795-808页

作者： Xingju Cai Deren Han School of Mathematical Sciences and key laboratory for Numerical simulation of Large Scale Complex Systems of Jiangsu province Nanjing Normal University

Owing to its efficiency in solving some types of large-scale separable optimization problems with linear constraints, the convergence rate of the alternating direction method of multipliers(ADMM for short) has recently attracted significant attention. In this paper, we consider the generalized ADMM(G-ADMM), which incorporates an acceleration factor and is more efficient. Instead of using a solution measure that depends on a bounded set and cannot be easily estimated, we propose using the original ?-optimal solution measure, under which we prove that the G-ADMM converges at a rate of O(1/t). The new bound depends on the penalty parameter and the distance between the initial point and the solution set, which is more reasonable than the previous bound.

关键词： generalized alternating direction method of multipliers separable convex optimization iteration complexity sublinear convergence rate

Numerical simulation of the aerodynamic characteristics of heavy-duty trucks through viaduct in crosswind

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Journal of Hydrodynamics 2014年第3期26卷 394-399页

作者：胡兴军秦鹏廖磊郭鹏王靖宇杨博 State key laboratory of Automobile simulation and Control Jilin University

In our numerical simulation the hybrid mesh and the SST k-ω turbulence model are adopted to investigate the variations of the aerodynamic loads and the flow field of heavy-duty trucks while crossing a viaduct with 1.1 m high fences in a crosswind at a velocity of 20 m/s. The results show that, with the protection of a fence, the side force is weakened, and the rolling and yaw moments are strengthened while the truck is crossing the viaduct, which relatively reduces the roll-over safety and the driving stability of the truck. Meanwhile, the direction of the side force changes when the truck enters the viaduct, which makes the roll-over safety and the driving stability the lowest during the process.

关键词： computational fluid dynamics heavy-duty truck crosswind cross viaduct aerodynamic loads flow field

Tradeoffs in Covert Wireless Communication with a Controllable Full-Duplex Receiver

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China Communications 2022年第5期19卷 87-101页

作者： Yue Zhao Zan Li Danyang Wang Nan Cheng State key laboratory of Integrated Service Networks Xidian UniversityXi’an 710071Shaanxi ProvinceChina Collaborative Innovation Center of Information Sensing and Understanding Xi’an 710071Shaanxi ProvinceChina

This paper investigates the tradeoff of the communication link and the eavesdropping link in covert communication in the presence of a full-duplex(FD)*** a warden(Willie)attempts to detect the signal transmitted from a legitimate transmitter(Alice),the controllable FD receiver(Bob)can transmit with random power to impose interference uncertainty to Willie and force it to make an incorrect *** maximize the average transmission rate(ATR)of Alice-Bob and the average covert probability(ACP)for Willie,we propose a multi-objective optimization framework to optimize Bob’s power uncertainty range(PUR)and spatial position jointly,subject to the sufficient condition for covert communication and the none-deployed-zone(NDZ).Due to the presence of multiple optimization objectives and nonconvex constraints,the nondominated sorting genetic algorithm II(NSGA-II)is utilized to explore the Pareto front and to give a set of solutions that reflect tradeoffs between the two conflicting *** results reveal that the solutions determined by the NSGA-II have larger values for both ATR and ACP than the other two *** also show the positive effect of the width of the PUR of Bob on the Pareto front.

关键词： covert communication multi-objective optimization full-duplex resource allocation