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Differential transform method for solving Richards' equation

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Applied Mathematics and Mechanics(English Edition) 2016年第2期37卷 169-180页

作者： Xi CHEN ying dai School of Aerospace Engineering and Applied Mechanics Tongji University

An approximate solution to Richards＇ equation is presented, mathematically describing a sort of unsaturated single phase fluid flow in porous media. The approach is a differential transform method （DTM） with interm... 详细信息

关键词： approximate analytical solution Richavds' equation differential transform method (DTM) intermediate variable

Neighborhood predictors of short sleep duration and bedtime irregularity among children in the United States: results from the 2019-2020 National Surveyof Children's Health

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World Journal of Pediatrics 2024年第1期20卷 73-81页

作者： ying dai Jianghong Liu School of Nursing University of Pennsylvania418 Curie Blvd.Room 426Claire M.Fagin HallPhiladelphiaPA19104-6096USA

Background Environmental factors may contribute to short sleep duration and irregular bedtime in *** factors and children's sleep duration and bedtime regularity remain a less investigated *** aim of this study was to investigate the national and state-level proportions of children with short sleep duration and irregular bedtime and their neighborhood *** A total of 67,598 children whose parents completed the National Survey of Children's Health in 2019-2020 were included in the ***-weighted Poisson regression was used to explore the neighborhood predictors of children's short sleep duration and irregular *** The prevalence of short sleep duration and irregular bedtime among children in the United States(US)was 34.6%[95%confidence interval(CI)=33.8%-35.4%]and 16.4%(95%CI=15.6%-17.2%)in 2019-2020,*** neighborhoods,supportive neighborhoods,and neighborhoods with amenities were found to be protective factors against children's short sleep duration,with risk ratios ranging between 0.92 and 0.94,P<*** with detracting elements were associated with an increased risk of short sleep duration[risk ratio(RR)=1.06,95%CI=1.00-1.12]and irregular bedtime(RR=1.15,95%CI=1.03-1.28).Child race/ethnicity moderated the relationship between neighborhood with amenities and short *** Insufficient sleep duration and irregular bedtime were highly prevalent among US children.A favorable neighborhood environment can decrease children's risk of short sleep duration and irregular *** the neighborhood environment has implications for children's sleep health,especially for children from minority racial/ethnic groups.

关键词： Child National Survey of Children's Health Neighborhood.Sleep Social determinants of health

Elongation of skyrmions by Dzyaloshinskii-Moriya interaction in helimagnetic films

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Rare Metals 2022年第9期41卷 3150-3159页

作者： ying-ying dai Han Wang Teng Yang Adekunle O.Adeyeye Zhi-Dong Zhang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang110016China Department of Electrical and Computer Engineering National University of SingaporeSingapore117583Singapore Department of Physics Durham UniversityDurhamDH13LEUK

Distortion of skyrmions arouses much attention recently due to the exotic topologic al and dynamic *** the formation mechanism and dynamical behavior of the deformed skyrmions promotes practical spintronic ***,as a typical form of deformation,has been discovered both in experiments and in ***,the intrinsic mechanism is ***,the coexistence of zero-field circular and elongated skyrmions in helimagnetic films is *** elongated skyrmions,which are determined by the intrinsic Dzyaloshinskii-Moriya interaction(DMI),carry the same topological charge as the circular ones and show the skyrmion Hall *** dynamics reveal again the significant role of the intrinsic DMI playing in the skyrmion elongation.

关键词： Elongated skyrmions Dzyaloshinskii-Moriya interaction Skyrmion Hall effect Zero-field skyrmions

New Residual Based Stabilization Method for the Elasticity Problem

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Advances in Applied Mathematics and Mechanics 2018年第1期10卷 100-113页

作者： Minghao Li Dongyang Shi ying dai College of Science Henan University of TechnologyZhengzhouHenan 450001China School ofMathematics and Statistics ZhengzhouUniversityZhengzhouHenan 450001China School of Aerospace Engineering and AppliedMechanics Tongji UniversityShanghai 200092China

In this paper,we consider the mixed finite element method(MFEM)of the elasticity problem in two and three dimensions(2D and 3D).We develop a new residual based stabilization method to overcome the inf-sup difficulty,and use Langrange elements to approximate the stress and *** new method is unconditionally stable,and its stability can be obtained directly from C´ea’s *** error estimates for the H1-norm of the displacement and H(div)-norm of the stress can be obtained at the same *** results show the excellent stability and accuracy of the new method.

关键词： Elasticity MFEM residuals stabilization

Assessment of the induced radioactivity in the treatment room of the heavy-ion medical machine in Wuwei using PHITS

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Nuclear Science and Techniques 2023年第2期34卷 153-166页

作者： ying Luo Sheng‑Cong Huang Hui Zhang Hai‑Jun Mao Qiang Li Zhong‑ying dai Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Science Lanzhou 730000China Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine Lanzhou 730000China Lanzhou University Lanzhou 730000China

Carbon-ion radiotherapy(CIRT)offers unique physical and biological advantages over photon ***,some materials and devices in the CIRT treatment room become radioactive under bombardment by therapeutic carbon-ion beams due to nuclear reactions,thereby leading to possible radiation hazards to medical staff and additional and unwanted doses to *** study assessed the level of induced radioactivity in the treatment room of the Heavy-Ion Medical Machine(HIMM)in *** Carlo simulations using PHITS were performed for a conservative case under the conditions of maximum beam energy and intensity provided by the HIMM *** geometry and configuration of Treatment Room 2 of the HIMM facility in Wuwei were *** evaluated the activation of air,the phantom,and the components of the beamline,such as the primary collimator(PC),ridge filter(RF),and multileaf collimator(MLC).For air activation,we calculated the medical staff immersion external exposure and inhalation internal exposure caused by the corresponding *** phantom activation,we estimated the additional dose to the patient’s family members owing to secondary photons after *** addition,the exemption or non-exemption of the component material activation was *** results showed that external radiation caused by air activation was the main source of the annual effective dose at approximately 0.5 mSv/*** induced radioactivity exposure to family members of a patient after CIRT was approximately 40μSv,sufficiently lower than the public dose limit of 1 mSv/*** induced radioactivity of the PC,RF,and MLC was all above the exempt levels after the devices were retired,whereas the induced radioactivity of the RS and compensator could reach the exempt levels after one patient *** study indicated that medical staff engaged in CIRT should stay away from the high-dose-rate area of induced radioactivity along the beam direction,shorten the residence time in

关键词： activation approximate thereby

Monte Carlo study of the neutron ambient dose equivalent at the heavy ion medical machine in Wuwei

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Nuclear Science and Techniques 2022年第9期33卷 111-125页

作者： Sheng-Cong Huang Hui Zhang Kai Bai ying Luo Hai-Jun Mao Zhong-ying dai University of Chinese Academy of Sciences Beijing 100049China Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China School of Nuclear Science and Technology Lanzhou UniversityLanzhou 730000China

The use of carbon-ion radiotherapy(CIRT)is gradually *** to the generation of high-energy secondary neutrons during CIRT,its use presents new challenges in radiation ***,secondary neutron dose distributions must be explored and evaluated under clinical scenarios based on different treatment ***,neutron dose and energy spectrum measurements are often *** can be primarily attributed to the inherent limitations of most neutron detectors,such as their unsuitability for spectral measurements and inaccurate responses to neutrons with energies above 20 *** calculation methods based on probabilistic statistical theory are fast and convenient for neutron dose *** this study,external secondary neutron doses at the heavy ion medical machine in Wuwei,which is equipped with a passive beam delivery system,were calculated using the Monte Carlo *** dependence of neutron doses on various treatment parameters(incident carbon-ion beam energy,spatial location,field size,and spread-out Bragg peak(SOBP)width)was ***,the feasibility of applying an analytical model to predict the ambient dose equivalent was *** the combination involving an energy of 400 MeV=u and SOBP width of 6 cm,the ambient dose equivalent per therapeutic dose(H=D)at the isocenter was 79.87 mSv=Gy:The H=D value decreased rapidly with increasing spatial distance and slightly with increasing aperture size and SOBP *** H=D values derived from the Monte Carlo simulations were in good agreement with the results reported in the *** analytical model could be used to quickly predict the H=D value along the incidence direction of the beam with an error of less than 20%.Thus,our study contributes to the understanding of the relationship between neutron radiation and treatment configuration parameters,which establishes a basis for predicting non-therapeutic radiation doses in CIRT.

关键词： Carbon-ion radiotherapy Passive beam delivery Secondary neutrons Monte Carlo method

An Emergency Blood Allocation Approach Considering Blood Group Compatibility in Disaster Relief Operations

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International Journal of Disaster Risk Science 2019年第1期10卷 74-88页

作者： Zu-Jun Ma Ke-Ming Wang ying dai School of Management Yangtze University Institute for Logistics and Emergency Management School of Economics and Management Southwest Jiaotong University School of Information Science and Technology Southwest Jiaotong University

Large-scale sudden-onset disasters may cause massive injuries and thus place great pressure on the emergency blood supplies of local blood banks. When blood is in short supply, blood products gathered urgently to a local blood center should be appropriately allocated to blood banks in the affected area. Moreover, ABO/Rh(D) compatibilities among blood groups must be considered during emergency situations. To minimize the total unmet demand of blood products considering the optimal ABO/Rh(D)-compatible blood substitution scheme, a mixed integer programming model is developed and solved efficiently by using a greedy heuristic algorithm. Finally, a numerical example derived from the emergency blood supply scenario of the Wenchuan Earthquake is presented to verify the proposed model and algorithm. The results show that considering ABO/Rh(D)-compatible blood substitution can remarkably increase the efficiency of emergency blood allocation while lowering blood shortage, and the preference order of possible ABO/Rh(D)-compatible substitutions has an influence on the allocation solution.

关键词： Blood group compatibility Blood substitution Disaster relief Emergency blood allocation Greedy heuristic algorithm

Third-order topological insulators with wallpaper fermions in Tl_(4)PbTe_(3)and Tl_(4)SnTe_(3)

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npj Computational Materials 2022年第1期8卷 1461-1467页

作者： Ning Mao Hao Wang ying dai Baibiao Huang Chengwang Niu School of Physics State Key Laboratory of Crystal MaterialsShandong UniversityJinanChina

Nonsymmorphic symmetries open up horizons of exotic topological boundary states and even generalize the bulk–boundary correspondence,which,however,the third-order topological insulator in electronic materials are still ***,by means of the symmetry analysis and k·p models,we uncover the emergence of long-awaited third-order topological insulators and the wallpaper fermions in space group I4/mcm(No.140).Based on this,we present the hourglass fermion,fourfold-degenerate Dirac fermion,and Möbius fermion in the(001)surface of Tl_(4)XTe_(3)(X=Pb/Sn)with a nonsymmorphic wallpaper group ***,16 helical corner states reside on eight corners in Kramers pair,rendering the real electronic material of third-order topological *** importantly,a time-reversal polarized octupole polarization is defined to uncover the nontrivial third-order topology,as is implemented by the 2nd and 3rd order Wilson loop *** results could considerably broaden the range of wallpaper fermions and lay the foundation for future experimental investigations of third-order topological insulators.

关键词： topological insulator boundary

2D spontaneous valley polarization from inversion symmetric single-layer lattices

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npj Computational Materials 2022年第1期8卷 617-623页

作者： Ting Zhang Xilong Xu Baibiao Huang ying dai Yandong Ma School of Physics State Key Laboratory of Crystal MaterialsShandong UniversityShandanan Street 27Jinan250100China

2D spontaneous valley polarization attracts great interest both for its fundamental physics and for its potential applications in advanced information technology,but it can only be obtained from inversion asymmetric single-layer crystals,while the possibility to create 2D spontaneous valley polarization from inversion symmetric single-layer lattices remains ***,starting from inversion symmetric single-layer lattices,a general design principle for realizing 2D spontaneous valley polarization based on van der Waals interaction is mapped *** first-principles calculations,we further demonstrate the feasibility of this design principle in a real material of *** remarkably,such design principle exhibits the additional exotic out-of-plane ferroelectricity,which could manifest many distinctive properties,for example,ferroelectricity-valley coupling and magnetoelectric *** explored design-guideline and phenomena are applicable to a vast family of 2D *** work not only opens up a platform for 2D valleytronic research but also promises the fundamental research of coupling physics in 2D lattices.

关键词： materials symmetric lattices