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Finite element analysis for inclined wellbore stability of transversely iso-tropic rock with HMCD coupling based on weak plane strength criterion

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Science China(Technological Sciences) 2017年第4期60卷 624-637页

作者： WANG YongLiang ZHUANG Zhuo LIU ZhanLi YANG HengLin LI ChenFeng Applied Mechanics Laboratory School of Aerospace Engineering Tsinghua University zienkiewicz centre for computational engineering & energy safety research institute College of Engineering Swansea University Drilling research institute China National Petroleum Corporation

The finite element analysis(FEA) technology by hydraulic-mechanical-chemical-damage(HMCD) coupling is proposed in this paper for inclined wellbore stability analysis of water-sensitive and laminated rock, developed basing on the recently established FEA technology for transversely isotropic rock with hydraulic-mechanical-damage(HMD) coupling. The chemical activity of the drilling fluid is considered as phenomenological hydration behavior, the moisture content and parameters of rock considering hydration could be determined with time. The finite element(FE) solutions of numerical wellbore model considering the chemical activity of drilling fluid, damage tensor calculation and weak plane strength criterion for transversely isotropic rock are developed for researching the wellbore failure characteristics and computing the time-dependent collapse and fracture pressure of laminated rock as shale reservoirs. A three-dimensional FE model and elastic solid deformation and seepage flow coupled equations are developed, and the damage tensor calculation technology for transversely isotropic rock are realized by introducing effect of the hydration and the stress state under the current load. The proposed method utilizing weak plane strength criterion fully reflects the strength parameters in rock matrix and weak plane. To the end, an effective and reliable numerically three-step FEA strategy is well established for wellbore stability analysis. Numerical examples are given to show that the proposed method can establish efficient and applicable FE model and be suitable for analyzing the timedependsolutions of pore pressure and stresses, and the evolution region considering the hydration surrounding wellbore,furthermore to compute the collapse cycling time and the safe mud weight for collapse and fracture pressure of transversely isotropic rock.

关键词： finite element analysis wellbore stability transversely isotropic rock hydraulic-mechanical-chemical-damage coupling weak plane strength criterion

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Comparison between wave generation methods for numerical simulation of bimodal seas

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Water Science and engineering 2016年第1期9卷 3-13页

作者： Daniel A.Thompson Harshinie Karunarathna Dominic Reeve energy & Environment research Group Zienkiewicz Centre for Computational Engineering Swansea UniversityBay Campus

This paper describes an investigation of the generation of desired sea states in a numerical wave model. Bimodal sea states containing energetic swell components can be coastal hazards along coastlines exposed to large oceanic fetches. Investigating the effects of long-period bimodal seas requires large computational domains and increased running time to ensure the development of the desired sea state. Long computational runs can cause mass stability issues due to the Stokes drift and wave reflection, which in turn affect results through the variation of the water level. A numerical wave flume, NEWRANS, was used to investigate two wave generation methods： the wave paddle method, allowing for a smaller domain; and the internal mass source function method, providing an open boundary allowing reflected waves to leave the domain. The two wave generation methods were validated against experimental data by comparing the wave generation accuracy and the variance of mass in the model during simulations. Results show that the wave paddle method not only accurately generates the desired sea state but also provides a more stable simulation, in which mass fluctuation has less of an effect on the water depth during the long-duration simulations. As a result, it is suggested that the wave paddle method with active wave absorption is preferable to the internal wave maker option when investigating intermediate-depth long-period bimodal seas for long-duration simulations.

关键词： Wave modeling Wave generation RANS Swell wave Bimodal sea Long-period waves

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A Comprehensive Survey on Federated Learning Applications in computational Mental Healthcare

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Computer Modeling in engineering & Sciences 2025年第1期142卷 49-90页

作者： Vajratiya Vajrobol Geetika Jain Saxena Amit Pundir Sanjeev Singh Akshat Gaurav Savi Bansal Razaz Waheeb Attar Mosiur Rahman Brij B.Gupta institute of Informatics and Communication University of DelhiDelhi110021India Maharaja Agrasen College University of DelhiDelhi110096India Computer engineering Ronin InstituteMontclairNJ 07043USA Department of research and Innovation Insights2TechinfoJaipur302001India University centre for research and Development(UCRD) Chandigarh UniversityChandigarh140413India Management Department College of Business AdministrationPrincess Nourah bint Abdulrahman UniversityRiyadh11671Saudi Arabia CCRI&Department of Computer Science and Information engineering Asia UniversityTaichung413Taiwan Symbiosis centre for Information Technology(SCIT) Symbiosis International UniversityPune411057India Center for Interdisciplinary research University of Petroleum and Energy Studies(UPES)Dehradun248007India

Mental health is a significant issue worldwide,and the utilization of technology to assist mental health has seen a growing *** aims to alleviate the workload on healthcare professionals and aid *** applications have been developed to support the challenges in intelligent healthcare ***,because mental health data is sensitive,privacy concerns have *** learning has gotten some *** research reviews the studies on federated learning and mental health related to solving the issue of intelligent healthcare *** explores various dimensions of federated learning in mental health,such as datasets(their types and sources),applications categorized based on mental health symptoms,federated mental health frameworks,federated machine learning,federated deep learning,and the benefits of federated learning in mental health *** research conducts surveys to evaluate the current state of mental health applications,mainly focusing on the role of Federated Learning(FL)and related privacy and data security *** survey provides valuable insights into how these applications are emerging and evolving,specifically emphasizing FL’s impact.

关键词： Depression emotional recognition intelligent healthcare systems mental health federated learning stress detection sleep behaviour

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Preface for special section on coastal flood risk

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Water Science and engineering 2016年第1期9卷 1-2页

作者： Dominic Reeve energy & Environment research Group Zienkiewicz Centre for Computational EngineeringSwansea UniversityBay Campus

Global concerns about changes in the world＇s climate have been well documented. The consequent impacts on coastal cities, agriculture, and coastal mariculture are difficult to quantify, but it is clear that there is ... 详细信息

关键词： Preface for special section on coastal flood risk

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Performance of a data-driven technique applied to changes in wave height and its effect on beach response

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Water Science and engineering 2016年第1期9卷 42-51页

作者： José M.Horrillo-Caraballo Harshinie Karunarathna Shun-qi Pan Dominic Reeve energy&Environment research Group Zienkiewicz Centre for Computational EngineeringSwansea UniversityBay CampusSwansea SA1 8ENUK Hydro-environmental research centre School of EngineeringCardiff UniversityCardiff CF24 3AAUK

In this study the medium-term response of beach profiles was investigated at two sites： a gently sloping sandy beach and a steeper mixed sand and gravel beach. The former is the Duck site in North Carolina, on the east coast of the USA, which is exposed to Atlantic Ocean swells and storm waves, and the latter is the Milford-on-Sea site at Christchurch Bay, on the south coast of England, which is partially sheltered from Atlantic swells but has a directionally bimodal wave exposure. The data sets comprise detailed bathymetric surveys of beach profiles covering a period of more than 25 years for the Duck site and over 18 years for the Milford-on-Sea site. The structure of the data sets and the data-driven methods are described. Canonical correlation analysis （CCA） was used to find linkages between the wave characteristics and beach profiles. The sensitivity of the linkages was investigated by deploying a wave height threshold to filter out the smaller waves incrementally. The results of the analysis indicate that, for the gently sloping sandy beach, waves of all heights are important to the morphological response. For the mixed sand and gravel beach, filtering the smaller waves improves the statistical fit and it suggests that low-height waves do not play a primary role in the medium-term morohological resoonse, which is primarily driven by the intermittent larger storm waves.

关键词： Beach profile Canonical correlation analysis Data-driven technique Empirical orthogonal function Forecast Statistical model Wave height threshold

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Discrete Element Modelling of Dynamic Behaviour of Rockfills forResisting High Speed Projectile Penetration

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Computer Modeling in engineering & Sciences 2021年第5期127卷 721-735页

作者： Tingting Zhao Y.T.Feng Jie Zhang Zhihua Wang Zhiyong Wang College of Mechanical and Vehical engineering Taiyuan University of TechnologyTaiyuan030024China zienkiewicz centre for computational engineering Swansea UniversitySwanseaSA28PPUK

This paper presents a convex polyhedral based discrete element method for modelling the dynamic behaviour ofrockfills for resisting high speed projectile penetration. The contact between two convex polyhedra is defined by theMinkowski overlap and determined by the GJK and EPA algorithm. The contact force is calculated by a Minkowskioverlap based normal model. The rotational motion of polyhedral particles is solved by employing a quaternionbased orientation representation scheme. The energy-conserving nature of the polyhedral DEM method ensures arobust and effective modelling of convex particle systems. The method is applied to simulate the dynamic behaviourof a rockfill system under impact of a high speed projectile. The rockfill sample is generated by a three-dimensionalVoronoi meso method with a specific particle size distribution. The penetrating process of the projectile strikingthe rockfill target is simulated. Some physical quantities associated with the projectile such as the residual velocity,penetration resistance, and deflection angle are monitored which can reflect the influence of the characteristics ofthe rockfill target on its anti-penetration performance. It can be concluded that the developed polyhedral DEMmethod is a very promising numerical approach in analysing the dynamic behaviour of rockfill systems subject tohigh speed projectile impact.

关键词： Discrete element method minkowski overlap polyhedral particles rockfill protection system high speed projectile penetration

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A two-dimensional double layer-averaged model of hyperconcentrated turbidity currents with non-Newtonian rheology

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International Journal of Sediment research 2023年第6期38卷 794-810页

作者： Yining Sun Ji Li Zhixian Cao Alistair George Liam Borthwick State Key Laboratory of Water Resources engineering and Management Wuhan University zienkiewicz centre for computational engineering Faculty of Science and EngineeringSwansea University institute for Infrastructure and Environment University of Edinburgh School of engineering Computing and MathematicsUniversity of Plymouth

Hyperconcentrated turbidity currents typically display non-Newtonian characteristics that influence sediment transport and morphological evolution in alluvial ***,hydro-sedimentmorphological processes involving hyperconcentrated turbidity currents are poorly understood,with little known about the effect of the non-Newtonian *** current paper extends a recent twodimensional double layer-averaged model to incorporate non-Newtonian constitutive *** extended model is benchmarked against experimental and numerical data for cases including subaerial mud flow,subaqueous debris flow,and reservoir turbidity *** computational results agree well with observations for the subaerial mud flow and independent numerical simulations of subaqueous debris *** between the non-Newtonian and Newtonian model results become more pronounced in terms of propagation distance and sediment transport rate as sediment concentration *** model is then applied to turbidity currents in the Guxian Reservoir planned for middle Yellow River,China,which connects to a tributary featuring hyperconcentrated sediment-laden *** non-Newtonian model predicts slower propagation of turbidity currents and more significant bed aggradation at the confluence between the tributary Wuding River and the Yellow River in the reservoir than its Newtonian *** difference in model performance could be of considerable importance when optimizing reservoir operation schemes.

关键词： Double layer-averaged model Non-Newtonian rheology Mud flow Reservoir turbidity current Yellow River

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非球形颗粒离散元接触模型和方法三十年发展概述

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Acta Mechanica Sinica 2023年第1期39卷 44-84页

作者：冯云田 zienkiewicz centre for computational engineering Faculty of Science and Engineering Swansea University UK

离散元方法(DEM)自1979年提出以来,在过去四十年中取得了显著的发展.本文旨在选择性地概述离散元方法中非球形颗粒接触模型和计算方法三十年来的主要进展,并更多地关注早期的发展.本综述主要关注接触模型的几何方面,不涉及与材料相关的... 详细信息

离散元方法(DEM)自1979年提出以来,在过去四十年中取得了显著的发展.本文旨在选择性地概述离散元方法中非球形颗粒接触模型和计算方法三十年来的主要进展,并更多地关注早期的发展.本综述主要关注接触模型的几何方面,不涉及与材料相关的物理问题.首先分类描述了非球形颗粒几何形状的各种表示方案,然后对几乎所有非球形颗粒接触模型和方法进行了系统性地梳理和讨论,除概述这些方法和模型的关键思想、主要概念以及原创性的计算方法外,还详细讨论了它们的演变和相互关系.最后还简要评述了每种方法可能存在的问题和未解决的问题,并指出可能的解决方案.

关键词：离散元方法几何形状接触模型非球形颗粒分类描述计算方法原创性发展概述

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Multi-layer perceptron-based data-driven multiscale modelling of granular materials with a novel Frobenius norm-based internal variable

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Journal of Rock Mechanics and Geotechnical engineering 2024年第6期16卷 2198-2218页

作者： Mengqi Wang Y.T.Feng Shaoheng Guan Tongming Qu zienkiewicz centre for computational engineering Faculty of Science and EngineeringSwansea UniversitySwanseaWalesSA18EPUK institute of Theoretical and computational Physics Graz University of TechnologyGraz8010Austria Department of Civil and Environmental engineering Hong Kong University of Science and TechnologyClearwater BayKowloonHong KongChina

One objective of developing machine learning(ML)-based material models is to integrate them with well-established numerical methods to solve boundary value problems(BVPs).In the family of ML models,recurrent neural networks(RNNs)have been extensively applied to capture history-dependent constitutive responses of granular materials,but these multiple-step-based neural networks are neither sufficiently efficient nor aligned with the standard finite element method(FEM).Single-step-based neural networks like the multi-layer perceptron(MLP)are an alternative to bypass the above issues but have to introduce some internal variables to encode complex loading *** this work,one novel Frobenius norm-based internal variable,together with the Fourier layer and residual architectureenhanced MLP model,is crafted to replicate the history-dependent constitutive features of representative volume element(RVE)for granular *** obtained ML models are then seamlessly embedded into the FEM to solve the BVP of a biaxial compression case and a rigid strip footing *** obtained solutions are comparable to results from the FEM-DEM multiscale modelling but achieve significantly improved *** results demonstrate the applicability of the proposed internal variable in enabling MLP to capture highly nonlinear constitutive responses of granular materials.

关键词： Granular materials History-dependence Multi-layer perceptron(MLP) Discrete element method FEM-DEM Machine learning

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Hybrid magnetorheological elastomers enable versatile soft actuators

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npj computational Materials 2022年第1期8卷 1546-1559页

作者： Miguel Angel Moreno-Mateos Mokarram Hossain Paul Steinmann Daniel Garcia-Gonzalez Department of Continuum Mechanics and Structural Analysis Universidad Carlos III de MadridAvda.de la Universidad 3028911LeganésMadridSpain zienkiewicz centre for computational engineering Faculty of Science and EngineeringSwansea UniversitySA18ENSwanseaUK institute of Applied Mechanics University of Erlangen-NurembergEgerland Str.5ErlangenGermany Glasgow computational engineering centre School of EngineeringUniversity of GlasgowG128QQGlasgowUK

Recent advances in magnetorheological elastomers(MREs)have posed the question on whether the combination of both soft-and hard-magnetic particles may open new routes to design versatile multifunctional ***,we conceptualise ultra-soft hybrid MREs(≈1–10 kPa stiffness)combining experimental and computational ***,a comprehensive experimental characterisation is *** results unravel that the magneto-mechanical performance of hybrid MREs can be optimised by selecting an adequate mixing ratio between ***,a multi-physics computational framework provides insights into the synergistic magneto-mechanical interactions at the *** particles amplify the magnetisation and hard particles contribute to torsional *** numerical results suggest that the effective response of hybrid MREs emerges from these intricate ***,we uncover exciting possibilities to push the frontiers of MRE *** are demonstrated by simulating a bimorph beam that provides actuation flexibility either enhancing mechanical bending or material stiffening,depending on the magnetic stimulation.

关键词： versatile magneto enable

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