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While there is high confidence that human activities have increased the likelihood and severity of hot extreme events over many parts of the world, there is notable spread in quantitative estimates of anthropogenic influence even on a single event. To better understand the uncertainty of attribution results, here we compare different event attribution methods using the 2015 July–August record-breaking heat event in northwestern China as a case study. To address the anthropogenic influence on the likelihood of the extreme event, we employ attribution runs with two modeling strategies—atmosphere-only and coupled simulations—with different conditioning. In atmosphere-only attribution runs, given the observed sea surface boundary conditions and external forcings in 2015, it is estimated that anthropogenic forcing has increased the likelihood of hot extremes such as that observed in 2015 in the target region, by approximately 27 and 12 times in MIROC5 and HadGEM3-A-N216, respectively. In Coupled Model Intercomparison Project Phase 5 (CMIP5) fully coupled attribution runs, given the external forcing at the 1961–2015 level and regardless of sea surface boundary conditions, there is a 21-fold increase in the likelihood of similar heat events due to anthropogenic forcing. The differences in quantitative attribution results can arise from modeling strategies, which are tightly linked to different conditioning in attribution. Specifically, different ocean boundary conditions, external forcings, and air-sea coupling processes contribute to different attribution results between the two modeling strategies. Within each modeling strategy, model uncertainty affects quantitative attribution conclusions. The comparison of different attribution methods provides a better understanding of the uncertainty of attribution results, which is useful in synthesizing and interpreting attribution results.

The Mirim and Patos Lagoons form the largest lagoon complex in South America. Wind is one of the dominant climatic elements of circulation and water levels in the basin. Therefore, we aimed to better understand the effects of wind on the Mirim–São Gonçalo watershed by applying the MGB hydrological model and to assess whether it would produce satisfactory results for modeling. Various tests were performed to determine the best representation of the processes involved and the observed levels. The best results were obtained with the inclusion of sub-daily wind data in the simulation and also the downstream boundary condition by using the observed water level data at the sluice dam of the São Gonçalo channel. The results showed that the model could successfully simulate the levels and demonstrated the importance of including the wind when modeling the hydrodynamic processes of large lake environments. HIGHLIGHTS What is the numerical effect of introducing wind influence in the inertial flux propagation method?; What are the optimal values of the coefficient of wind friction and parameterization for minibasin connections to obtain the best simulation of the lagoon?; Does the inclusion of lock level information in the SGC as a downstream boundary condition and hourly winds benefit the level representation?

The terahertz current generated by a photoconductive device (PCD) saturates as the power of the input optical pump is increased. This behavior is induced by various screening effects that stem from the interactions between electromagnetic (EM) fields and semiconductor carriers. In this work, these screening effects are numerically analyzed for the first time using a fully-coupled multiphysics approach. Unlike the previously developed simulation frameworks, this approach rigorously models the nonlinear coupling between the EM fields and the carriers and therefore is capable of accounting for the screening effects. It is demonstrated that the results obtained using this multiphysics approach and actual experiments are in excellent agreement. The optical- and radiation-field screening effects are identified in the simulation results and the optical-field screening is found to play a more dominant role in the saturation of the PCD output under high optical pump power levels.

The coupling of chemically induced degradation and mechanical damage is fundamental to investigate the durability of load-bearing cement-based materials subject to aggressive environments. This study is devoted to the incorporation of a reactive transport model and non-local damage model to integrate the complete process of chemical degradation and appropriate propagation of mechanical damage in the framework of coupled chemo-mechanical degradation. The chemical degradation of cement-based materials subject to leaching solution is principally concluded as the dissolution of portlandite and decalcification of C–S–H, and the reduction of Young's modulus is evaluated based on the microstructure of cement-based materials by the Mori–Tanaka scheme. The displacement-based non-local damage model is incorporated to capture the post-peak behaviour of the leached mortar beam in three-point bending test. The significance of coupling chemical and mechanical damage for the degraded beam is demonstrated by comparing the fully coupled damage with outcomes of the non-coupled case.

Nonlinear systems of differential equations with delay, which are mathematical models of fully connected networks of impulse neurons, are considered. Purpose of this work is to study the dynamic properties of one special class of solutions to these systems. Large parameter methods are used to study the existence and stability in сonsidered models of special periodic motions – the so-called group dominance or k-dominance modes, where k ∈ N. Results. It is shown that each such regime is a relaxation cycle, exactly k components of which perform synchronous impulse oscillations, and all other components are asymptotically small. The maximum number of stable coexisting group dominance cycles in the system with an appropriate choice of parameters is 2m − 1, where m is the number of network elements. Conclusion. Considered model with maximum possible number of couplings allows us to describe the most complex and diverse behavior that may be observed in biological neural associations. A feature of the k-dominance modes we have considered is that some of the network neurons are in a non-working (refractory) state. Each periodic k-dominance mode can be associated with a binary vector (α1, α2, . . . , αm), where αj = 1 if the j-th neuron is active and αj = 0 otherwise. Taking this into account, we come to the conclusion that these modes can be used to build devices with associative memory based on artificial neural networks.

Persistent hot–dry or cold–wet summer weather can have significant impacts on agriculture, health, and the environment. For northwestern Europe, these weather regimes are typically linked to, respectively, blocked or zonal jet stream states. The fundamental dynamics underlying these circulation states are still poorly understood. Edward Lorenz postulated that summer circulation may be either fully or almost intransitive, implying that part of the phase space (capturing circulation variability) cannot be reached within one specific summer. If true, this would have major implications for the predictability of summer weather and our understanding of the drivers of interannual variability of summer weather. Here, we test the two Lorenz hypotheses (i.e., fully or almost intransitive) for European summer circulation, capitalizing on a newly available very large ensemble (2000 years) of present-day climate data in the fully coupled global climate model EC-Earth. Using self-organizing maps, we quantify the phase space of summer circulation and the trajectories through phase space in unprecedented detail. We show that, based on Markov assumptions, the summer circulation is strongly dependent on its initial state in early summer with the atmospheric memory ranging from 28 days up to ~45 days. The memory is particularly long if the initial state is either a blocked or a zonal flow state. Furthermore, we identify two groups of summers that are characterized by distinctly different trajectories through phase space, and that prefer either a blocked or zonal circulation state, respectively. These results suggest that intransitivity is indeed a fundamental property of the atmosphere and an important driver of interannual variability.

A comparative study of the seismic performance of 2×1 pile groups considering different degrees of batter (0° for vertical, 10° and 20°) embedded in single homogeneous liquefiable sand through fully coupled three-dimensional dynamic analyses is presented. The effects of inertial interaction are considered with structures having two different periods. The performance of pile groups is investigated for the fixed and pinned pile to cap connections for both floating and end bearing types of pile groups. Slenderness ratios of piles were also varied to enable a comprehensive understanding. Investigations have been carried out for three earthquake motions having varied dominant frequencies. It is observed that batter pile groups in liquefiable soils provide beneficial effects on piles and superstructure responses for both fixed and pinned head pile to cap connections for long period structures. However, for short period structures, a beneficial effect is most evident for fixed head connection.

A recent structural model of a plate is extended to include a nonuniform temperature differential that varies in time using a modal expansion. The nonlinear structural plate model with first-order ...

A chemo-thermo-mechanical problem is solved using a peridynamic approach to investigate crack propagation in non-reinforced concrete at early-age. In the present study, the temperature evolution and the variation of the hydration degree in conjunction with the mechanical behaviour of cement-based materials are examined. Firstly, a new peridynamic model is introduced to solve fully coupled chemo-thermal problems by satisfying thermal equilibrium condition and hydration law simultaneously and then the effects of the chemo-thermal analysis are imposed in the mechanical framework to investigate all the interactions. The proposed approach is used to solve 2D chemo-thermo-elastic problems and then it is applied to investigate the fracture of concrete structures. Additionally, we examine the accuracy of the method by comparing the crack paths, temperature and hydration degree with those achieved by applying other numerical methods and the experimental data available in the literature. A good agreement is obtained between all sets of results.

pH-sensitive hydrogels are promising materials to be employed in microfluidic devices, especially microvalves. In this paper, a theory of transient swelling of pH-sensitive micro-valve is presented. A transient constitutive model that captures electrical, chemical, and mechanical fields is considered to model the swelling phenomenon. The diffusion of ions into the hydrogel, the electromigration, and convection are described by implementing the Nernst-Planck equation. Assuming Gent model, hydrogel is considered as a compressible hyperelastic material and osmotic pressure is assumed as an external loading. Due to benefits of in-plane valves, a design of the micro-valve is studied. Design simplicity and great sealing are vital factors which can be considered as an advantage of this valve for fabrication. This design and modeling approach has not been used for pH-sensitive hydrogels in earlier works. Thus, we have studied the transient swelling of pH-sensitive hydrogel microvalve, when effects of fluid-structure-interaction are examined on valve performance. It is noted that in most previous studies, equilibrium conditions have been assumed. While considering transient fully-coupled fluid-structure-interaction is necessary to capture a more realistic modeling. The results illustrate that the microvalve blocks the channel much earlier than reaching the equilibrium-state, which implies importance of the transient behavior of hydrogels.

In this work, a promising fully coupled meshfree numerical approach is extended and implemented for the first time in the field of linear static thermoelasticity. A real meshfree method, the so-called finite pointset method (FPM), is applied and implemented in order to solve the strong/classical form of the governing partial differential equations for static linear thermoelasticity. Several benchmark problems are numerically solved in order to show the proposed coupled FPM numerical performance. The presented FPM meshfree approach shows excellent behavior for 2D linear static thermoelasticity problems even for complex geometries.

This article reports the development, stability analysis, and experimental evaluation of a novel adaptive identification (AID) algorithm for underwater vehicles (UVs) for on‐line estimatio...

Fracture parameters are important for oil and gas production. In this paper, we establish a fully coupled gas flow and effective stress model for the single well multi‐stage hydraulic fracturing shale gas reservoir and analyze the optimal fracture parameters of this model. Firstly, the reservoir consists of single‐porosity medium zone, dual‐porosity medium zone, and hydraulic fracture zone. Then, on the basis of the effective stress mechanism, the theory of porous elastic medium, evolution of fractal dimensions, and the mechanism of fluid transportation, we establish an apparent permeability model of matrix and fracture system to couple the deformation of reservoir and gas flow in matrix. After that, the partial differential equation is solved by COMSOL and verified using the field shale gas production data of Barnett and Marcellus. Finally, the model is used to optimize the fracture parameters. The results show that by increasing the half‐length of hydraulic fracture, the gas production gets the maximum growth, followed by increasing the fracture diversion capacity and width of hydraulic fractures. For the shale gas reservoir with large‐fractured and relatively high permeability, increasing the length of hydraulic fractures can bring higher production, while for the micro‐fractured and low‐permeability, hydraulic fractures with complex shapes can contribute to production increase.

This paper improves a simplified soil hysteresis model for one-dimensional fully coupled effective stress analysis of site seismic response that addresses the limitations of existing hyperbolic soi...

In the present work, a fully coupled thermo-mechanical analysis is presented to obtain the desired bend angle in the sheet made of AM30 magnesium alloy. The finite element method (FEM) based softwa...

This study explored the fully coupled thermo-hydro-chemical response of natural gas hydrate (NGH) recovery, where the factors considered are that the hydrate decomposes from solid to methane and wa...

Conventional seepage–heat transfer models in simulating the heat transfer between fluid and rock in fractures mainly involve one-way coupling and do not consider the influence of temperature on the seepage. Moreover, it is an enormous challenge to define parameters of the explicit heat transfer between the rock and fluid. In order to resolve these shortcomings, a two-way fully coupled model of the seepage–heat transfer in the fractured rock was established in the present study. Based on the original geometric structure of the experimental device, combined with the actual engineering scale, the local dynamic heat transfer coefficient of the fractured rock was established, which is related to the fracture aperture, flow velocity and thermal parameters. Then, the proposed model was verified through the experiment and excellent agreement was achieved in this regard. It was found that the dynamic heat transfer coefficient changes the temperature distribution of fluid and rock in the original static heat transfer coefficient fracture system. The proposed model simplifies the parameters required for the calculation of the heat transfer coefficient. These parameters are related to characteristic variables, such as velocity and rock temperature, and can be simply obtained from standard laboratory tests.

A fully coupled dynamic model is presented in this paper by considering the effect of matric suction, varying parameters in connection with saturation, stratification and transverse isotropy. This model can describe separate flows of two immiscible fluids in layered transversely isotropic unsaturated poroelastic media subjected to harmonically dynamic loads. The ordinary differential matrix equations of this model are derived based on Hankel integral transform and a series of algebraic manipulations. Then the final solution is obtained by conducting the extended precise integration method, and further verified against the existing solution. Numerical examples are carried out to demonstrate the effects of saturation, transversely isotropic parameters, angular frequency and soil thickness on dynamic behavior of unsaturated porous media.

In industrial machining operations, many turning processes are carried out under wet conditions. In contrast, most simulation tools are only suitable for dry cutting processes due to challenges of modeling fluid-structure-interactions (FSI). In this paper, a wet, fully coupled cutting simulation using the Finite-Pointset-Method (FPM) is presented and validated for industrially relevant cylindrical turning. To facilitate the required reduction of the calculation effort, different routines like adaptive numerical discretization are applied. The results indicate different cutting fluid effects like evaporation areas around the chip.

Summary The popular cohesive zone model (CZM) that only features decreasing cohesive traction along with crack separation might not adequately represent the fracturing behavior in organic-rich shale because of increased ductility. This paper proposes a novel CZM that can realize various traction/separation laws (TSLs) by a unified formulation to better represent the increased ductility of organic-rich shale. This modified CZM was implemented in a fully coupled in-house poroelastic extended-finite-element-method (XFEM) framework that has been comprehensively verified against the latest analytical solutions. The implications of increased ductility in different forms on hydraulic fracturing were studied using the newly designed progressive parametric study. First, the shape of the TSL affects the hydraulic fracturing given the same cohesive crack energy and tensile strength, which further indicates the necessity of the newly proposed TSL. Second, the initial tensile strength, controlling when the cohesive crack starts propagating, has the greatest effect on the hydraulic fracturing among all TSL shape parameters. The effects of TSL parameters become less significant as the fracturing-fluid viscosity increases. Finally, Young's modulus among four common poroelastic parameters most significantly affects the brittleness of rock formation and hydraulic-fracture lengths. The increase in cohesive energy accompanied by the decrease of Young's modulus can greatly reduce the hydraulic-fracture length under the same injection volume.

This work aims at developing a fully coupled numerical model by integrating the two-dimensional shallow water equations with entropy theory. TVD Mac-Cormack predictor-corrector finite difference sc...

SummaryA modular multiphysics reservoir-simulation system is developed that has the capability of simulating multiphase/multicomponent/thermal flow, poro-elasto/plastic geomechanics, and hydraulic-fracture evolution. The focus of the work is on the full-physics hydraulic-fracture-evolution-simulation capability of the multiphysics simulation system. Fracture-growth computations use a cohesive-zone model as part of the computation of fracture-propagation criterion. The cohesive-zone concept is developed using energy-release rates and cohesive stresses. They capture the strain-softening behavior of deforming porous material consistent with real-life observations of poro-plastic deformation. Thus, they can be reliably used within both poro-elastic and poro-plastic geomechanics applications, unlike the conventional stress-intensity-factor-based fracture-propagation criterion.The partial-differential equations (PDEs) that govern the Darcy-scale multiphase/multicomponent/thermal flow, poro-elasto/plastic geomechanics, hydraulic-fracture evolution, and laminar channel flow in the fracture are tightly coupled to each other to give rise to a numerical protocol solvable by the fully implicit method. The ensuing nonlinear system of equations is solved by use of a novel adaptively damped Newton-Raphson method.Example fully coupled single-phase isothermal-flow, geomechanics, and hydraulic-fracture-growth simulations are analyzed to demonstrate the predictive power of the simulation system. Numerical-model predictions of fracture length/radius and width are validated against analytical solutions for plane-strain and ellipsoid-shaped fractures, respectively. Results indicate that the simulation system is capable of modeling hydraulic-fracture evolution accurately by use of the cohesive-zone model as the propagation criterion. We also simulate and explore the sensitivities around a real-life hydraulic-fracture-growth problem by fully accounting for the thermal-, multiphase-, and compositional-flow effects.

The datasets of the Chinese Academy of Sciences (CAS) Flexible Global Ocean–Atmosphere–Land System (FGOALS-f3-L) model for the baseline experiment of the fully coupled runs in the Diagnostic, Evaluation and Characterization of Klima (DECK) common experiments of phase 6 of the Coupled Model Intercomparison Project (CMIP6) are described in this study. The CAS FGOALS-f3-L model team submitted the piControl run with a near equilibrium ocean state for 561 model years, and 160-year integrations for three ensemble members of abrupt-4× CO2 and 1pctCO2, respectively. The ensemble members restart from the 600, 650 and 700 model years in the piControl run, respectively. The baseline performances of the model are validated in this article. The preliminary evaluation suggests that the CAS FGOALS-f3-L model can preserve the long-term stability well for a mean net radiation flux of 0.31 W m−2 at the top of the atmosphere, and a limited decreasing trend of −0.03 W m−2/100 yr. The global annual mean SST is 16.45°C for the 561-year mean, with an increase of 0.03°C/100 yr. The model captures the basic spatial patterns of climate-mean SST and precipitation, but still underestimates the SST over the warm pool. The coupled model mitigates the precipitation bias in the ITCZ compared with the results from CMIP5. Moreover, the model’s climate sensitivity represented by the equilibrium climate sensitivity has been reduced from 4.5°C in CMIP5 to 3.0°C in CMIP6. All these datasets contribute to the benchmark of model behaviors for the desired continuity of CMIP.

This paper aims to study the effect of stress-diffusion interactions and its effect on the localization of the plastic strain in an elastoplastic material using a fully coupled chemo-mechanical sys...

Safety gear is one of the most important devices of elevators for its core function is to brake the over-speed cabin with friction. The frictional braking of elevator safety gear is a fully coupled...

Purpose This study aims to propose another alternative numerical modelling tool, i.e. ABAQUS, to simulate a fully coupled seepage-deformation analysis in unsaturated slope subjected to rainfall infiltration. Design/methodology/approach The effect of rainfall infiltration on the response of pore water pressure and factor of safety has been analysed and discussed. The results of this study have also been validated based on the results of field monitoring and previous numerical modelling. Findings The results from ABAQUS show a better agreement with those from field monitoring compared to other numerical modelling tools. Originality/value The procedures adopted in this study can be adopted and used as a guide to model similar slope problems in ABAQUS.

This paper study a type of fully coupled mean-field forward-backward stochastic differential equations with jumps under the monotonicity condition, including the existence and the uniqueness of the solution of our equation as well as the continuity property of the solutions with respect to the parameters. Then we establish the stochastic maximum principle for the corresponding optimal control problems and give the applications to mean-variance portfolio problems and linear-quadratic problems, respectively.

In this paper, non-isothermal analysis of an automatic multi-stage cold forging process of a ball-stud is conducted using a new material model which is a closed form function of strain, temperature and strain rate covering low and warm temperatures for high-strength stainless steel SUS304. An assembled die structural analysis scheme is employed for revealing the detailed die stresses, which is of great importance for process and die design for metal forming of the materials with high strengths. Die elastic deformation is dealt with to predict final geometries of material with higher accuracy. A complete analysis model is proposed to be used for optimal design of process and die designs in automatic multi-stage cold forging of high-strength materials.

Low-frequency variability in the south Indian Ocean is studied by analyzing 200 years of output from a fully coupled climate model simulation. At time scales of 2–10 years, the variability is dominated by westward-propagating features that form on the eastern side of the basin. Using feature tracking and clustering, the spatiotemporal characteristics and preferred pathways of the propagating features are identified and studied in detail. By comparison of the phase speed and vertical structure of the propagating anomalies identified by the feature tracking with linear theory, we conclude that these features are likely mode 1 or 2 baroclinic planetary waves. The effects of this low-frequency variability on the climate system is investigated. By analysis of the mixed-layer temperature budget, it is shown that at particular geographic locations, the propagating features can substantially modify the near-surface ocean and induce significant fluxes of heat into the atmosphere. In turn, these heat fluxes can drive a coherent atmospheric response, although this response does not appear to feed back onto the ocean. Finally, we discuss the implications for the interannual climate predictability.

In Part I, a density driven damage mechanics (D3-M) approach and its application to model mechanical damage in concrete are presented. In this study, chemical and chemo-mechanical damage in concret...