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2.5D scattering of incident plane SV waves by a canyon in layered half-space

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Earthquake Engineering and Engineering Vibration 2010年第4期9卷 587-595页

作者： ba Zhenning Liang Jianwen Department of Civil Engineering Tianjin University Tianjin 300072 China Key Laboratory of Coast Civil Structure Safety （ Tianjin University） Ministry of Education

This paper presents a 2.5D scattering of incident plane SV waves by a canyon in a layered half-space by using the indirect boundary element method （IBEM）. A free field response analysis is performed to provide the displacements and stresses on the boundary of the canyon where fictitious uniform moving loads are applied to calculate the Green＇s *** for the displacements and stresses. The amplitudes of the loads are determined by the boundary conditions. The free field displacements are added to the fictitious uniform moving loads induced displacements and the total response is obtained. Numerical calculations are performed for a canyon with homogenous and in one layer over bedrock. The effects of the thickness and stiffness of the layer on the amplification are studied and discussed.

关键词： layered half-space canyon plane SV wave amplification scattering surface layer indirect boundaryelement method

The effect of propagation delay on the dynamic evolution of the Bitcoin blockchain

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Digital Communications and Networks 2020年第2期6卷 157-166页

作者： Moustapha ba MODAL’X(Laboratoire de Modélisation aléatoire)of UniversitéParis Nanterre(Paris X) MODAL’X is the Mathematics and Computer Sciences laboratory of UniversitéParis Nanterre(Paris X)ministerial label EA 3454UFR SEGMIdépartement Mathématiques-Informatique200 avenue de la République92000NanterreFrance

This paper analyzes the selfish-mine strategy in the Bitcoin blockchain introduced in 2013 by *** and *** strategy could be used by a colluding pool of miners to earn more than their fair share of the mining revenue and in consequence to force other honest miners to join them to decrease the variance of their revenues and make their monthly revenues more *** is a very dangerous dynamic that could allow the rogue pool of miners to go toward a majority by accumulating powers of news adherents and control the entire *** that the propagation delay of information between any two miners in the network,which is not negligible and follows a normal distribution with mean proportional to the physical distance between the two miners,and a constant variance independent of others'delays,we prove that no guarantee can be given about the success or failure of the selfish-mine attack because of the variability of information propagation in the network.

关键词： Blockchain Bitcoin Mining Selfish-mine attack Propagation delay of information

移植物厚度对角膜内皮失代偿行简易后弹力层角膜内皮移植效果的影响

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中国组织工程研究 2025年第6期29卷 1199-1207页

作者：巴颜红高明宏陈颖欣中国人民解放军北部战区总医院辽宁省沈阳市110000

背景:研究表明较薄移植物视力恢复更快、排斥风险更低,国内缺乏对内皮移植术后不同植片厚度的临床疗效分析,因此,确定最佳移植物厚度对于提高手术疗效至关重要。目的:评价简易后弹力层剥离内皮角膜移植术后不同植片厚度对视力恢复及其... 详细信息

背景:研究表明较薄移植物视力恢复更快、排斥风险更低,国内缺乏对内皮移植术后不同植片厚度的临床疗效分析,因此,确定最佳移植物厚度对于提高手术疗效至关重要。目的:评价简易后弹力层剥离内皮角膜移植术后不同植片厚度对视力恢复及其他预后指标的影响。方法:选取2013年1月至2023年2月在北部战区总医院接受简易后弹力层剥离内皮角膜移植手术治疗的角膜内皮失代偿患者共72例(72眼),其中薄植片组(0.05);③两组患者继发性青光眼、植片免疫排斥、植片移位等术后并发症发生率比较差异无显著性意义(P>0.05);④两组术后1年植片生存率比较差异无显著性意义(93.8%,92.3%,P>0.05);⑤结论:简易后弹力层剥离内皮角膜移植术是一种安全有效的角膜内皮移植手术方式,其术后疗效与传统后弹力层剥离内皮角膜移植术相似,而且植片植入方式更为简便。较薄植片能够更早提供最佳矫正视力,更早完成角膜重塑,因此在治疗角膜内皮失代偿疾病时,优先选择薄移植物来提高恢复时间。

关键词：后弹力层撕除角膜内皮移植术角膜内皮失代偿继发性青光眼植片移位原发移植失败植片排斥角膜内皮细胞数角膜移植

Characterization of Arithmetic Functions that Preserve the Sum-of-squares Operation

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Acta Mathematica Sinica,English Series 2014年第4期30卷 689-695页

作者： Bojan baI Department of Mathematics and Informatics University of Novi Sad

We characterize all functions f ： N → C such that f（m^2 ＋ n^2） = f（m）^2 ＋ f（n）^2 for all m, n ∈ N. It turns out that all such functions can be grouped into three families, namely f ≡ 0, f（n） = ±n （subject to some restrictions on when the choice of the sign is possible） and f（n） =±l/2（again subject to some restrictions on when the choice of the sign is possible）.

关键词： Arithmetic function functional equation sum of squares

Analysis of Heat and Mass Transfer for a Single-Planar-Anode-Supported Solid Oxide Fuel Cell Considering Internal Reforming

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Journal of Thermal Science 2020年第3期29卷 697-707页

作者： ZHANG Zhuqian WANG Yulei ba Liming Institute of Thermal Engineering School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China Beijing Key Laboratory of Flow and Heat Transfer of Phase Changing in Micro and Small Scale Beijing 100044China National Institute of Clean-and-Low-Carbon Energy Beijing 102211China

The temperature uniformity and component concentration distributions in solid oxide fuel cells during operating processes can influence the cell electrochemical and thermal characteristics.A three-dimensional thermal-fluid numerical model including electrochemical reactions and water-gas-shift(WGS)reaction for a single channel solid oxide fuel cell was developed to study the steady-state characteristics,which include distributions of the temperature(T),temperature gradient((35)T/(35)x),and fuel *** was shown that the maximum temperature(Tmax)changed with operating voltage and the maximum temperature gradient(((35)T/(35)x)max)occurred at the inlet of the channel of a solid oxide fuel cell by ***,the natural convection condition had a great influence on T and(35)T/(35)*** thermal stress generated by temperature differences was the key parameter and increasing the convection heat-transfer coefficient can greatly reduce the thermal *** addition,the results also showed that there were lower temperature gradients and lower current density at high working voltage;therefore,choosing the proper operating voltage can obtain better cell performance.

关键词： three-dimensional numerical simulation internal reforming reaction solid oxide fuel cell temperature gradient fuel utilization

Time-dependent diffusion magnetic resonance imaging:measurement,modeling,and applications

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第10期25卷 765-787页

作者： Ruicheng ba Liyi KANG Dan WU Key Laboratory for Biomedical Engineering of Ministry of Education Department of Biomedical EngineeringCollege of Biomedical Engineering&Instrument ScienceZhejiang UniversityHangzhou 310027China

Increasingly,attention is being directed towards time-dependent diffusion magnetic resonance imaging(TDDMRI),a method that reveals time-related changes in the diffusional behavior of water molecules in biological tissues,thereby enabling us to probe related microstructure *** ongoing improvements in hardware and advanced pulse sequences,significant progress has been made in applying TDDMRI to clinical *** development of accurate mathematical models and computational methods has bolstered theoretical support for TDDMRI and elevated our understanding of molecular *** this review,we introduce the concept and basic physics of TDDMRI,and then focus on the measurement strategies and modeling approaches in short-and long-diffusion-time ***,we discuss the challenges in this field,including the requirement for efficient scanning and data processing technologies,the development of more precise models depicting time-dependent molecular diffusion,and critical clinical applications.

关键词： Time-dependent diffusion Diffusion magnetic resonance imaging(dMRI) Microstructure imaging Microstructural model

Comprehensive Evaluation Method for Traffic Flow Data Quality based on Grey Correlation Analysis and Particle Swarm Optimization

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Journal of Systems Science and Systems Engineering 2024年第1期33卷 106-128页

作者： Wei ba baojun Chen Qi Li School of Automation and Electrical Engineering Dalian Jiaotong UniversityDalian116028China Faculty of Electronic Information and Electrical Engineering Dalian University of TechnologyDalian116023China

Nowadays,data are more and more used for intelligent modeling and prediction,and the comprehensive evaluation of data quality is getting more and more attention as a necessary means to measure whether the data are usable or ***,the comprehensive evaluation method of data quality mostly contains the subjective factors of the evaluator,so how to comprehensively and objectively evaluate the data has become a bottleneck that needs to be solved in the research of comprehensive evaluation *** order to evaluate the data more comprehensively,objectively and differentially,a novel comprehensive evaluation method based on particle swarm optimization(PSO)and grey correlation analysis(GCA)is presented in this *** first,an improved GCA evaluation model based on the technique for order preference by similarity to an ideal solution(TOPSIS)is ***,an objective function model of maximum difference of the comprehensive evaluation values is built,and the PSO algorithm is used to optimize the weights of the improved GCA evaluation model based on the objective function ***,the performance of the proposed method is investigated through parameter analysis.A performance comparison of traffic flow data is carried out,and the simulation results show that the maximum average difference between the evaluation results and its mean value(MDR)of the proposed comprehensive evaluation method is 33.24%higher than that of TOPSIS-GCA,and 6.86%higher than that of *** proposed method has better differentiation than other methods,which means that it objectively and comprehensively evaluates the data from both the relevance and differentiation of the data,and the results more effectively reflect the differences in data quality,which will provide more effective data support for intelligent modeling,prediction and other applications.

关键词： Data quality comprehensive evaluation particle swarm optimization grey correlation analysis traffic flow data

Diffraction of SH-waves by topographic features in a layered transversely isotropic half-space

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Earthquake Engineering and Engineering Vibration 2017年第1期16卷 11-22页

作者： ba Zhenning Liang Jianwen Zhang Yanju Department of Civil Engineering Tianjin University Tianjin 300072 China Key Laboratory of Coast Civil Structure Safety ( Tianjin University) Ministry of Education Tianjin 300072 China

Abstract： The scattering of plane SH-waves by topographic features in a layered transversely isotropic （TI） half-space is investigated by using an indirect boundary element method （IBEM）. Firstly, the anti-plane dynamic stiffness matrix of the layered TI half-space is established and the free fields are solved by using the direct stiffness method. Then, Green＇s functions are derived for uniformly distributed loads acting on an inclined line in a layered TI half-space and the scattered fields are constructed with the deduced Green＇s functions. Finally, the free fields are added to the scattered ones to obtain the global dynamic responses. The method is verified by comparing results with the published isotropic ones. Both the steady-state and transient dynamic responses are evaluated and discussed. Numerical results in the frequency domain show that surface motions for the TI media can be significantly different from those for the isotropic case, which are strongly dependent on the anisotropy property, incident angle and incident frequency. Results in the time domain show that the material anisotropy has important effects on the maximum duration and maximum amplitudes of the time histories.

关键词： wave scattering and diffraction Green's function transversely isotropic SH-waves indirect boundaryelement method

P-wave velocity prediction in porous medium with liquid-pocket patchy saturation

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Applied Mathematics and Mechanics(English Edition) 2015年第11期36卷 1427-1440页

作者： Jiawei LIU Weitao SUN Jing ba Zhou Pei-Yuan Center for Applied Mathematics Tsinghua University Department of Computational Geophysics Xi'an Jiaotong University

It becomes increasingly clear that non-uniform distribution of immiscible fluids in porous rock is particularly relevant to seismic wave dispersion. White proposed a patchy saturation model in 1975, in which spherical gas pockets were located at the center of a liquid saturated cube. For an extremely light and compressible inner gas, the physical properties can be approximated by a vacuum with White＇s model. The model successfully analyzes the dispersion phenomena of a P-wave velocity in gas-water- saturated rocks. In the case of liquid pocket saturation, e.g., an oil-pocket surrounded by a water saturated host matrix, the light fluid-pocket assumption is doubtful, and few works have been reported in White＇s framework. In this work, Poisson＇s ratio, the bulk modulus, and the effective density of a dual-liquid saturated medium are formulated for the heterogeneous porous rocks containing liquid-pockets. The analysis of the difference between the newly derived bulk modulus and that of White＇s model shows that the effects of liquid-pocket saturation do not disappear unless the porosity approaches zero. The inner pocket fluid can no longer be ignored. The improvements of the P-wave velocity predictions are illustrated with two examples taken from experiments, i.e., the P-wave velocity in the sandstone saturated by oil and brine and the P-wave velocity for heavy oils and stones at different temperatures.

关键词： White's model porous medium P-wave dispersion liquid pocket