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Fabrication and Statics Performance of Pyramidal Lattice Stitched Foam Sandwich Composites

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Computer Modeling in Engineering & Sciences 2021年第3期126卷 1251-1274页

作者： yun zhao Shi Yan Jiale Jia Department of Engineering Mechanics Harbin University of Science and TechnologyHarbinChina

In this study,the pyramidal lattice stitched foam sandwich composite materials were manufactured by integrating top and bottom panels with pyramidal lattice core to overcome the weak interface between the core and the skins of the sandwich *** influence of the reinforcing core rods on the mechanical properties including compressive,shear,and three-point bending performances of the foam sandwich compositematerialswere revealed through theoretical analysis and comparative *** theoretical predictions were consistent with the experimental *** test,shear test and three-point bending test were *** experimental results show that the core rods can significantly improve the compressive performance and energy absorption efficiency of the pyramidal lattice stitched foam sandwich *** effect is related to the diameter of the core *** core rod with large diameter has better *** with the foamsandwich structure,the pyramidal lattice reinforcing foam composites have stronger shear and bending *** failure modes and failure mechanisms of the pyramidal lattice stitched foam sandwich structure under the shear load are *** failure modes and failure mechanisms of the pyramidal lattice stitched foam sandwich structure under the three-point bending load are also *** study concludes that compared with the foam sandwich structure,the overall mechanical properties of the lattice stitched foam sandwich structure composites are significantly improved.

关键词： Pyramidal lattice compressive performance shear three-point bending failure modes

The Role of T_(50) in the Classification of Gamma-ray Bursts

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Chinese Journal of Astronomy and Astrophysics 2004年第4期4卷 349-356页

作者： Xiao-Hongzhao Yi-PingQin yun-MingDong zhao-YangPeng yunnanObservatory ChineseAcademyofSciencesKunming650011

The role of T50 in classifying gamma-ray bursts (GRBs) is investigated. We take T50 = 0.7 s as the line of division and find that some bursts belonging to the class of long bursts defined by T90 ≥ 2 s now become short bursts (sample 1), while some belonging to the class of short bursts defined by T90 < 2 s now become long bursts (sample 2). We study how these sources are affected by the two methods of classification and find the change of classes of sample 1 is due to some peculiar properties of the light curves. Based on their characters, most of the bursts of sample 1 should be taken as short bursts.

关键词： gamma ray: bursts gamma ray: observations

Fluid discrimination incorporating amplitude variation with angle inversion and squirt flow of the fluid

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Petroleum Science 2022年第4期19卷 1592-1604页

作者： Yu-Rong Wang zhao-yun Zong Xing-Yao Yin China University of Petroleum QingdaoShandong266580China Shandong Provincial Key Laboratory of Deep Oil and Gas QingdaoShandong266580China Pilot National Laboratory for Marine Science and Technology(Qingdao) Shandong266580China

Pre-stack seismic inversion is an important method for fluid identification and reservoir characterization in exploration geophysics. In this study, an effective fluid factor is initially established based on Biot poroelastic theory, and a pre-stack seismic inversion method based on Bayesian framework is used to implement the fluid identification. Compared with conventional elastic parameters, fluid factors are more sensitive to oil and gas. However, the coupling effect between rock porosity and fluid content is not considered in conventional fluid factors, which may lead to fuzzy fluid identification results. In addition,existing fluid factors do not adequately consider the physical mechanisms of fluid content, such as squirt flow between cracks and pores. Therefore, we propose a squirt fluid factor(SFF) that minimizes the fluid and pore mixing effects and takes into account the squirt flow. On this basis, a novel P-wave reflection coefficient equation is derived, and the squirt fluid factor is estimated by amplitude variation with offset(AVO) inversion method. The new reflection coefficient equation has sufficient accuracy and can be utilized to estimate the parameters. The effectiveness and superiority of the proposed method in fluid identification are verified by the synthetic and field examples.

关键词： Fluid discrimination Poroelasticity theory Linearized seismic reflectivity Pre-stack seismic inversion Squirt flow of fluid

An integrated approach to improve the performance of lean–electrolyte lithium–sulfur batteries

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Journal of Energy Chemistry 2022年第4期31卷 585-592页

作者： Hualin Ye Jianguo Sun yun zhao Jim Yang Lee Department of Chemical and Biomolecular Engineering National University of Singapore119260Singapore Department of Mechanical Engineering National University of Singapore117575Singapore

While the sulfur conversion reaction kinetics in Li–S batteries is nowadays improved by the use of appropriate electrocatalysts,it remains a challenge for the batteries to perform well under the lean electrolyte condition where polysulfide shuttle,electrode passivation and the loss of electrolyte due to side reactions,are *** challenges are addressed in this study by the tandem use of a polysulfide conversion catalyst and a redox–targeting mediator in a gel sulfur ***,the gel cathode reduces the polysulfide mobility and hence the polysulfide shuttle and the passivation of the lithium anode by the crossover *** redox mediator restrains the deposition of inactive sulfur species in the cathode thereby enabling the Fe–N and Co–N co–doped carbon catalyst to prolong its catalytic ***,the integrated catalytic system is able to increase the discharge capacity of high–loading (6.8 mg cm^(-2)) lean–electrolyte (4.0μL mg^(-1)) Li–S batteries from~630 to~1316 m Ah g^(-1),concurrently with an improvement of the cycle life (600 cycles with 46%capacity retention at 1.0 m A cm^(-2)).Redox mediator assisted catalysis in a gel cathode is therefore an effective strategy to extend the application of the sulfur conversion catalyst in lean electrolyte Li–S batteries.

关键词： Redox mediators Gel electrolytes Polysulfide catalysis Lean electrolyte Lithium–sulfur batteries

THE RELATION OF DIMENSION, ENTROPY AND LYAPUNOV EXPONENT IN RANDOM CASE

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Analysis in Theory and Applications 2008年第2期24卷 129-138页

作者： yun zhao Department of Mathematics Suzhou University Suzhou 215006 P. R. China

We consider random systems generated by two-sided compositions of random surface diffeomorphisms, together with an ergodic Borel probability measure μ. Let D（μω） be its dimension of the sample measure, then we prove a formula relating D（μω） to the entropy and Lyapunov exponents of the random system, where D （μω） is dimHμω, dimBμm, or dimBμm.

关键词： Hausdorff dimension random dynamical systems

A NOTE ON MEASURE-THEORETIC EQUICONTINUITY AND RIGIDITY

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Acta Mathematica Scientia 2022年第2期42卷 769-773页

作者： Chiyi LUO yun zhao School of Mathematical Sciences and Center for Dynamical Systems and Differential Equations Soochow UniversitySuzhou 215006China

Given a topological dynamical system(X,T)and a T-invariant measureμ,let B denote the Borel σ-algebra on *** paper proves that(X,B,μ,T)is rigid if and only if(X,T)isμ-A-equicontinuous in the mean for some subsequence A of N,and a function f∈L^(2)(μ)is rigid if and only if f is μ-A-equicontinuous in the mean for some subsequence A of *** particular,this gives a positive answer to Question 4.11 in[1].

关键词： Measure-theoretic equicontinuity rigidity mean metric

Monitoring the change in horizontal stress with multi-wave time-lapse seismic response based on nonlinear elasticity theory

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Petroleum Science 2023年第2期20卷 815-826页

作者： Fu-Bin Chen zhao-yun Zong Xing-Yao Yin School of Geosciences China University of Petroleum East ChinaQingdaoShandong266580China Laoshan Laboratory QingdaoShandong266580China Shandong Provincial Key Laboratory of Deep Oil and Gas QingdaoShandong266580China

Monitoring the change in horizontal stress from the geophysical data is a tough challenge, and it has a crucial impact on broad practical scenarios which involve reservoir exploration and development, carbon dioxide (CO_(2)) injection and storage, shallow surface prospecting and deep-earth structure description. The change in in-situ stress induced by hydrocarbon production and localized tectonic movements causes the changes in rock mechanic properties (e.g. wave velocities, density and anisotropy) and further causes the changes in seismic amplitudes, phases and travel times. In this study, the nonlinear elasticity theory that regards the rock skeleton (solid phase) and pore fluid as an effective whole is used to characterize the effect of horizontal principal stress on rock overall elastic properties and the stress-dependent anisotropy parameters are therefore formulated. Then the approximate P-wave, SV-wave and SH-wave angle-dependent reflection coefficient equations for the horizontal-stress-induced anisotropic media are proposed. It is shown that, on the different reflectors, the stress-induced relative changes in reflectivities (i.e., relative difference) of elastic parameters (i.e., P- and S-wave velocities and density) are much less than the changes in contrasts of anisotropy parameters. Therefore, the effects of stress change on the reflectivities of three elastic parameters are reasonably neglected to further propose an AVO inversion approach incorporating P-, SH- and SV-wave information to estimate the change in horizontal principal stress from the corresponding time-lapse seismic data. Compared with the existing methods, our method eliminates the need for man-made rock-physical or fitting parameters, providing more stable predictive power. 1D test illustrates that the estimated result from time-lapse P-wave reflection data shows the most reasonable agreement with the real model, while the estimated result from SH-wave reflection data shows the largest bia

关键词： Monitoring change in horizontal stress Multi-wave reflection coefficients Nonlinear elasticity theory Time-lapse seismic data

Practical Constant-Size Ring Signature

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Journal of Computer Science & Technology 2018年第3期33卷 533-541页

作者： Meng-Jun Qin yun-Lei zhao Zhou-Jun Ma Shanghai Key Laboratory of Data Science School of Computer Science Fudan University Shanghai 201203 China State Key Laboratory of Integrated Services Networks Xidian University Xi'an 710126 China State Key Laboratory of Cryptology State Cryptology Administration Beijing 100878 China

Bitcoin has gained its popularity for almost 10 years as a ＂secure and anonymous digital currency＂. However, according to several recent researches, we know that it can only provide pseudonymity rather than real anonymity, and privacy has been one of the main concerns in the system similar to Bitcoin. Ring signature is a good method for those users who need better anonymity in cryptocurrency. It was first proposed by Rivest et al. based upon the discrete logarithm problem （DLP） assumption in 2006, which allows a user to sign a message anonymously on behalf of a group of users even without their coordination. The size of ring signature is one of the dominating parameters, and constant-size ring signature （where signature size is independent of the ring size） is much desirable. Otherwise, when the ring size is large, the resultant ring signature becomes unbearable for power limited devices or leads to heavy burden over the communication network. Though being extensively studied, currently there are only two approaches for constant-size ring signature. Achieving practical constant-size ring signature is a long-standing open problem since its introduction. In this work, we solve this open question. We present a new constant-size ring signature scheme based on bilinear pairing and accumulator, which is provably secure under the random oracle （RO） model. To the best of our knowledge, it stands for the most practical ring signature up to now.

关键词： ring signature constant size bilinear pairing accumulator

An Agent-Based Simulation Model of Knowledge Spillover Under the Influence of High-Speed Railway

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Journal of Systems Science and Information 2019年第2期10卷 99-114页

作者： yun zhao Chongren BI School of Public Policy&Management Tsinghua UniversityBeijing 100084China School of Economics and Management Beijing Jiaotong UniversityBeijing 100044China

The calculation for the influence of high-speed railway on knowledge spillover is based on the results of global instantaneous equilibrium in the mechanism explanation of knowledge spillover. In real production, the interaction between the high-speed railway and the regional innovation system is dynamic and local. In order to simulate the impact of high-speed railway on innovation activities in the time dimension, it is necessary to simulate scenarios under appropriate parameter assumptions. Based on the interaction of economic participants, a discrete evolutionary simulation model is established,which is helpful to predict and estimate the evolution of spatial effect of high-speed railway according to the theory of cellular automata. It is concluded that high-speed railway accelerates the formation of knowledge innovation industry cluster in the region in the process of regional knowledge innovation and evolution. Under the influence of high-speed railway, the node city will gradually evolve into a regional innovation center. By comparing the production evolution of knowledge innovation system with and without high-speed railway, the results show that high-speed railway has a more significant impact on knowledge spillover in higher knowledge privatization environment. Under the background of low labor migration rate, high-speed railway has increased the potential of regional innovation to external knowledge spillover. In the case of higher labor migration rate, the convergence rate of influence of high-speed railway on the concentration of innovation is faster.

关键词： knowledge spillover high-speed railway cellular automata exponential decay