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Progressive fragmentation of granular assemblies within rockslides: Insights from discrete-continuous numerical modeling

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Journal of Mountain Science 2024年第4期21卷 1174-1189页

作者： JIANG Hui ZHOU Yuande wang jinting DU Xiuli HUANG Hailong Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education Beijing University of TechnologyBeijing 100124China. Key Laboratory of the Hydrosphere Sciences of the Ministry of Water Resources Tsinghua UniversityBeijing 100084China China Three Gorges Construction Management Co. Ltd.Chengdu 610000China

Rock fragmentation plays a critical role in rock avalanches,yet conventional approaches such as classical granular flow models or the bonded particle model have limitations in accurately characterizing the progressive disintegration and kinematics of multi-deformable rock blocks during *** present study proposes a discrete-continuous numerical model,based on a cohesive zone model,to explicitly incorporate the progressive fragmentation and intricate interparticle interactions inherent in *** rock granular assemblies are released along an inclined plane and flow onto a horizontal *** numerical scenarios are established to incorporate variations in slope angle,initial height,friction coefficient,and particle *** evolutions of fragmentation,kinematic,runout and depositional characteristics are quantitatively analyzed and compared with experimental and field data.A positive linear relationship between the equivalent friction coefficient and the apparent friction coefficient is *** general,the granular mass predominantly exhibits characteristics of a dense granular flow,with the Savage number exhibiting a decreasing trend as the volume of mass *** process of particle breakage gradually occurs in a bottom-up manner,leading to a significant increase in the angular velocities of the rock blocks with increasing *** simulation results reproduce the field observations of inverse grading and source stratigraphy preservation in the *** propose a disintegration index that incorporates factors such as drop height,rock mass volume,and rock *** findings demonstrate a consistent linear relationship between this index and the fragmentation degree in all tested scenarios.

关键词： Rock fragmentation Rockslide Numerical modelling Discrete-continuous modelling Runout Cohesive zone model

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Numerical analysis on seismic response and failure mechanism of articulated pile−structure system in a liquefiable site from shaking-table experiments

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Frontiers of Structural and Civil Engineering 2024年第7期18卷 1117-1133页

作者： Pengfei DOU Hao LIU Chengshun XU jinting wang Yilong SUN Xiuli DU Department of Hydraulic Engineering Tsinghua UniversityBeijing 100084China Key Laboratory of Urban Security and Disaster Engineering of the Ministry of Education Beijing University of TechnologyBeijing 100124China

This study investigates the seismic response and failure mode of a pile-structure system in a liquefiable site by employing a numerical simulation model combined with the shaking-table results of a soil-pile-structure dynamic *** pile and soil responses obtained from the numerical simulations agreed well with the experimental *** slopes of the dynamic shear-stress-shear-strain hysteretic curves at different positions also exhibited a decreasing trend,indicating that the shear strength of the soil in all parts of the foundation *** peak acceleration of the soil and pile was not clearly amplified in the saturated sand layer but appeared to be amplified in the top *** maximum bending moments appeared in the middle and lower parts of the pile shaft;however,the shear forces at the corresponding positions were not *** can be observed from the deformation mode of the pile-group foundation that a typical bending failure is caused by an excessive bending moment in the middle of the pile shaft if the link between the pile top and cap is articulated,and sufficient attention should be paid to the bending failure in the middle of the pile shaft.

关键词： numerical simulation soil liquefaction pile foundation shaking-table experiment seismic responses failure model

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Mechanical regulation of lipid and sugar absorption by Piezo1 in enterocytes

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Acta Pharmaceutica Sinica B 2024年第8期14卷 3576-3590页

作者： Tian Tao Qing Shu Yawen Zhao Wenying Guo jinting wang Yuhao Shi Shiqi Jia Hening Zhai Hui Chen Cunchuan wang Geyang Xu Department of Physiology School of MedicineJinan UniversityGuangzhou 510632China Department of Metabolic and Bariatric Surgery the First Affiliated Hospital of Jinan UniversityGuangzhou 510630China Endoscopy Center the First Affiliated Hospital of Jinan UniversityGuangzhou 510630China Biotherapy Center Cell-gene Therapy Translational Medicine Research Centerthe Third Affiliated HospitalSun Yat-sen UniversityGuangzhou 510630China Key Laboratory of Viral Pathogenesis&Infection Prevention and Control(Jinan University) Ministry of EducationGuangzhou 510632China

Obesity is primarily caused by excessive intake as well as absorption of sugar and *** surge in distention pressure and intestinal motility accelerates the absorption of *** response of intestinal epithelial cells to mechanical stimulation is not fully ***1,a mechanosensitive ion channel,is widely expressed throughout the digestive ***,its function in intestinal nutrient absorption is not yet *** our study,excessive lipid deposition was observed in the duodenum of obese patients,while duodenal Piezo1-CaMKK2-AMPKa was decreased when compared to normal-weight *** high-fat diet condition,the Piezo1iKO mice exhibited abnormally elevated sugar and lipid absorption as well as severe lipid deposition in the duodenum and *** phenotypes were mainly caused by the inhibition of duodenal CaMKK2-AMPKa and the upregulation of SGLT1 and *** contrast,Yoda1,a Piezo1 agonist,was found to reduce intestinal lipid absorption in diet induced obese *** of Piezo1,stretch and Yoda1 inhibited lipid accumulation and the expression of DGAT2 and SGLT1,whereas knockdown of Piezo1 stimulated lipid accumulation and DGAT2 in Caco-2 *** study reveals a previously unexplored mechanical regulation of nutrient absorption in intestinal epithelial cells,which may shed new light on the therapy of obesity.

关键词： Piezo1 DGAT2 SGLT1 Lipid metabolism Obesity Mechanical sensing Intestinal lipid absorption Intestinal glucose absorption

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DISCRETE-TIME Geo/G/1 RETRIAL QUEUES WITH GENERAL RETRIAL TIME AND BERNOULLI VACATION

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Journal of Systems Science & Complexity 2012年第3期25卷 504-513页

作者： jinting wang Department of Mathematics Beijing Jiaotong University

This paper considers a discrete-time Geo/G/1 retrial queue where the retrial time has a general distribution and the server is subject to Bernoulli vacation policy. It is assumed that the server, after each service completion, begins a process of search in order to find the following customer to be served with a certain probability, or begins a single vacation process with complementary probability. This paper analyzes the Markov chain underlying the queueing system and obtain its ergodicity condition. The generating functions of the number of customers in the orbit and in the system are also obtained along with the marginal distributions of the orbit size when the server is idle, busy or on vacation. Finally, the author gives two stochastic decomposition laws, and as an application the author gives bounds for the proximity between the system size distributions of the model and the corresponding model without retrials.

关键词： Discrete-time queue general retrial time retrial queue stochastic decomposition vaca-tion.

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ON THE SINGLE SERVER RETRIAL QUEUE WITH PRIORITY SUBSCRIBERS AND SERVER BREAKDOWNS

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Journal of Systems Science & Complexity 2008年第2期21卷 304-315页

作者： jinting wang Department of Mathematics Beijing Jiaotong University Beijing 100044 China

The author concerned the reliability evaluation as well as queueing analysis of M1, M2/G1, G2/1 retrial queues with two different types of primary customers arriving according to independent Poisson flows. In the case of blocking, the first type of customers can be queued whereas the second type of customers must leave the service area but return after some random period of time to try their luck again. The author assumes that the server is unreliable and it has a service-type dependent, exponentially distributed life time as well as a service-type dependent, generally distributed repair time. The necessary and sufficient condition for the system to be stable is investigated. Using a supplementary variable method, the author obtains a steady-state solution for queueing measures, and the transient as well as the steady-state solutions for reliability measures of interest.

关键词： Priority queues reliability retrial queues server breakdowns.

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A RISK-AVERSE NEWSVENDOR MODEL WITH LIMITED CAPACITY AND OUTSOURCING UNDER THE CVAR CRITERION

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Journal of Systems Science and Systems Engineering 2015年第1期24卷 49-67页

作者： Zhenwei Luo jinting wang Wanting Chen Department of Mathematics School of ScienceBeijing Jiaotong University

For seasonal products, the retailers usually launch various marketing ettorts, llKe aaverusmg tmu promotion, to promote them in a selling season. While facing large demand from the customers, one should take the capacity constraint and outsotlrcing into consideration. Considering the shorten life cycles of most products, in this paper we adopt the traditional newsvendor model to investigate the optimal marketing effort along with optimal order quantity. We address the risk aversion issue and characterize the influence of the sellers＇ risk propensity with CVaR criterion, and we develop an effective algorithm to obtain the optimal strategy. The impact of sellers＇ risk propensity on the performance of the system is illustrated via numerical examples, The innovation of this paper is threefold. First, the optimal joint strategy of the marketing effort and order quantity is investigated and an efficient algorithm to find the optimal strategy is developed. Second, the capacity constraint option and an outsourcing strategy are studied jointly for excess products. Finally, the risk propensity of the seller and its influence are investigated by using the CVaR criterion, through which we obtain some new managerial insights.

关键词： Newsvendor model marketing effort order quantity CVaR capacity constraint,outsourcing

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Comparison of seismic fragility analysis methods for arch dams

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Earthquake Engineering and Engineering Vibration 2023年第1期22卷 173-189页

作者： Jin Aiyun Qiu Yixiang wang jinting Department of Hydraulic Engineering Tsinghua UniversityBeijing 100084China

This study focuses on the seismic fragility analysis of arch *** multiple stripe analysis(MSA),cloud analysis(CLA),and incremental dynamic analysis(IDA)methods are compared.A comprehensive dam-reservoir-foundation rock system,which considers the opening of contraction joints,the nonlinearity of dam concrete and foundation rock,the radiation damping effect of semi-unbounded foundation,and the compressibility of reservoir water,is used as a numerical example.225,80,and 15 earthquake records are selected for MSA,CLA,and IDA,*** results show that MSA provides satisfactory fragility analysis,while both CLA and IDA have assumptions that may lead to ***,MSA is the most reliable method among the three methods and is recommended for the fragility analysis of arch *** is also shown that the choice of demand level affects the reliability of fragility curves and the effect of the material uncertainty on the fragility of the dam is not significant.

关键词： arch dam seismic fragility analysis cloud analysis incremental dynamic analysis multiple stripe analysis

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Efficiency analysis of numerical integrations for finite element substructure in real-time hybrid simulation

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Earthquake Engineering and Engineering Vibration 2018年第1期17卷 73-86页

作者： wang jinting Lu Liqiao Zhu Fei State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China Changjiang Institute of Survey Planning Design and Research Wuhan 430010 China

Finite element（FE） is a powerful tool and has been applied by investigators to real-time hybrid simulations（RTHSs）. This study focuses on the computational efficiency, including the computational time and accuracy, of numerical integrations in solving FE numerical substructure in RTHSs. First, sparse matrix storage schemes are adopted to decrease the computational time of FE numerical substructure. In this way, the task execution time（TET） decreases such that the scale of the numerical substructure model increases. Subsequently, several commonly used explicit numerical integration algorithms, including the central difference method（CDM）, the Newmark explicit method, the Chang method and the Gui-λ method, are comprehensively compared to evaluate their computational time in solving FE numerical substructure. CDM is better than the other explicit integration algorithms when the damping matrix is diagonal, while the Gui-λ（λ = 4） method is advantageous when the damping matrix is non-diagonal. Finally, the effect of time delay on the computational accuracy of RTHSs is investigated by simulating structure-foundation systems. Simulation results show that the influences of time delay on the displacement response become obvious with the mass ratio increasing, and delay compensation methods may reduce the relative error of the displacement peak value to less than 5% even under the large time-step and large time delay.

关键词： real-time hybrid simulation computational efficiency numerical integration storage optimization time delay

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Optimal Design for a Retrial Queueing System with State-Dependent Service Rate

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Journal of Systems Science & Complexity 2017年第4期30卷 883-900页

作者： ZHANG Xuelu wang jinting MA Qing Department of Mathematics Beijing Jiaotong University School of Science Qilu University of Technology Department of Basic Courses Shandong Women’s University

This paper considers a single server retrial queue in which a state-dependent service policy is adopted to control the service rate. Customers arrive in the system according to a Poisson process and the service times and inter-retrial times are all exponentially distributed. If the number of customers in orbit is equal to or less than a certain threshold, the service rate is set in a low value and it also can be switched to a high value once this number exceeds the threshold. The stationary distribution and two performance measures are obtained through the partial generating functions. It is shown that this state-dependent service policy degenerates into a classic retrial queueing system without control policy under some conditions. In order to achieve the social optimal strategies, a new reward-cost function is established and the global numerical solutions, obtained by Canonical Particle Swarm Optimization algorithm, demonstrate that the managers can get more benefits if applying this state-dependent service policy compared with the classic model.

关键词： Particle swarm optimization algorithm retrial queues social optimal strategy statedependent service policy

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Delay-dependent stability and added damping of SDOF real-time dynamic hybrid testing

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Earthquake Engineering and Engineering Vibration 2010年第3期9卷 425-438页

作者： Chi Fudong wang jinting Jin Feng State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China

It is well-recognized that a transfer system response delay that reduces the test stability inevitably exists in real-time dynamic hybrid testing （RTDHT）. This paper focuses on the delay-dependent stability and added damping of SDOF systems in RTDHT. The exponential delay term is transferred into a rational fraction by the Pad6 approximation, and the delay-dependent stability conditions and instability mechanism of SDOF RTDHT systems are investigated by the root locus technique. First, the stability conditions are discussed separately for the cases of stiffness, mass, and damping experimental substructure. The use of root locus plots shows that the added damping effect and instability mechanism for mass are different from those for stiffness. For the stiffness experimental substructure case, the instability results from the inherent mode because of an obvious negative damping effect of the delay. For the mass case, the delay introduces an equivalent positive damping into the inherent mode, and instability occurs at an added high frequency mode. Then, the compound stability condition is investigated for a general case and the results show that the mass ratio may have both upper and lower limits to remain stable. Finally, a high-emulational virtual shaking table model is built to validate the stability conclusions.

关键词： real-time dynamic hybrid testing root locus analysis delay-dependent stability Pade approximation added damping

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