Scientifically and efficiently ensuring good air quality for important events is an issue of concern to the government. In addition to analysis based on historical data, advanced prediction before an ...event is essential for the government having ample time to take effective actions to improve air quality during the event period. Taking “the 2022 Olympic Winter Games (OWG)” as a typical case, a chemical transport model coupled with a tracer-tagged module was used to evaluate the air quality and source apportionment of ambient pollutants in the OWG host cities under historical and predicted meteorological conditions. Driven by the downscaling of meteorological fields from an operational real-time climate forecast system, the potential ability of air quality forecasting three months ahead was investigated, which was meaningful for designing control strategies. Sensitive simulations indicated that under unfavorable meteorological conditions, such as those during February 2014, both Beijing and Zhangjiakou faced a high risk of experiencing haze episodes, even based on current anthropogenic emission intensity. The contribution of the joint prevention and control region to Beijing and Zhangjiakou would become larger under worse meteorological conditions, which favor heavy air pollution. The source apportionment results indicated that strengthened emission control in cities including Beijing, Zhangjiakou and south of Beijing (Baoding, Langfang, Tianjin, and Tangshan) is effective for reducing haze episodes in the host cities. There is still a long way to make accurate daily fine particulate matter predictions on a seasonal-scale in advance; however, it could capture the trends in air quality in host cities around the OWG period three months ahead. The comparison of observations and predictions confirmed and highlighted the role of regional emission controls on the realization of the “OWG blue”.
•Regional transport became larger under conditions favoring heavy air pollution.•The trend of air quality was captured by seasonal-scale model forecasting.•Joint emission control measures ensured the realization of the “OWG blue”.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Oceanic transform faults formed at mid‐ocean ridges are intrinsic features of modern plate tectonics. Nevertheless, numerical mantle convection models typically struggle to reproduce the strike‐slip ...movement observed along transform faults on Earth. Instead, mantle convection models tend to produce mostly convergent and divergent plate boundaries. Based on regional visco‐(elasto)‐plastic thermomechanical models it has been demonstrated that a strong strain‐induced weakening of rocks has to be assumed in order to initiate and stabilize the characteristic orthogonal ridge‐transform spreading patterns. However, the physical origin of such intense rheological weakening remains unclear. Considering that in nature oceanic transform faults show a strongly reduced grain size, a potentially strong influence of grain size reduction processes on the rheological strength of these structures can be assumed. Employing 3‐D thermomechanical visco‐plastic models, we study the effect of grain size reduction on oceanic transform fault initiation. Our results show that ductile weakening induced by grain size reduction indeed results in sufficient localization to initiate a transform fault. Without any additional weakening mechanisms, transform faults in our models remain stable up to 2 Myr. We identify parameters that affect stability and longevity of the transform fault during the initiation phase, such as the grain damage formulation and grain growth prefactor. In our models, transform faults initiate in the brittle crust and propagate downward, thus indicating a top‐down initiated localization process. The observed grain size, rheology, and strain rate inside the shear zone of our models agree well with observations in nature; however, the longevity of natural examples cannot be reached.
Key Points
We successfully model transform fault initiation using grain size reduction as a ductile weakening mechanism
The initiation of a transform fault occurs in the crust; the ductile mantle plays an important role in maintaining the transform fault
Without employing brittle strain weakening, transform faults last around 2 Myr
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
•Analysis of dynamical damage process by establishing simulation model of particle water-jet coupling impact rock.•The effect factors of rock damage and failure depth were discussed with experiment ...and simulation.•The failure mechanism and damage expansion law were revealed by defining Gaussian points.
Aiming at the problems of difficult observation of rock damage mechanism and many influencing factors of rock-breaking process, the damage mechanism of particle water-jet coupling impact was studied. Based on SPH-FEM coupling algorithm, the numerical model of particle water-jet impact rock was established, and the mechanical properties of rock were characterized by JH-2 (Johnson Holmquist II) damage model. Then, damage evolution and failure effect under the impact of water-jet and particle water-jet were simulated. It shows that the failure of rock is a cyclic process of “damage–cumulative damage–failure–cumulative damage–failure”, which is mainly manifested as shear powder and tensile cracks. Meanwhile, particle water-jet coupling impact rock-breaking experiment system and methods were introduced and the comparison way of experiment and simulation was used to analyze the influence law of particle ratio, water-jet impact velocity, particle diameter, impact angle on rock damage and failure depth. The propagation law of transverse and longitudinal damage inside of rock was studied by defining Gaussian points and damage would often occur instantaneously which was basically microsecond level.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper presents a study of run-up/overtopping over a smooth impermeable dike with promenade using 2D and 3D mesh-based and mesh-free numerical models and results from 2D physical modelling for ...strong energetic incident waves. These waves induce plunging wave breaking and a complex water/air mixture turbulent flow before overtopped the dike, a challenging configuration for numerical models. The analysis is structured in two phases: (i) evaluates the results of 2D numerical and physical models for run-up and overtopping; (ii) compares qualitatively the results of 3D numerical models for overtopping over a dike with promenade between groins located in front of a slope beach. The results indicate that the main differences obtained in run-up and overtopping are due to differences in wave generation and active absorption systems used in physical and numerical models and in turbulent models used by the numerical models. These differences lead to changes on incident wave height and on wave breaking and, consequently, on reflection, run-up and overtopping over the structure. For 3D simulation, even if larger discrepancies were found on overtopping along the dike, mean wave overtopping discharge and water flow height at the crest of the groin head show a similar order of magnitude.
There is a growing interest for marine flooding related to recent catastrophic events and their unintended consequences in terms of casualties and damages, and to the increasing population and issues ...along the coasts in a context of changing climate. Consequently, the knowledge on marine flooding has progressed significantly for the last years and this review, focused on storm-induced marine submersions, responds to the need for a synthesis. Three main components are presented in the review: (1) a state-of-the-art on marine submersions from the viewpoint of several scientific disciplines; (2) a selection of examples demonstrating the added value of interdisciplinary approaches to improve our knowledge of marine submersions; (3) a selection of examples showing how the management of future crises or the planning efforts to adapt to marine submersions can be supported by new results or techniques from the research community.
From a disciplinary perspective, recent progress was achieved with respect to physical processes, numerical modeling, the knowledge of past marine floods and vulnerability assessment. At a global scale, the most vulnerable coastal areas to marine flooding with high population density are deltas and estuaries. Recent and well-documented floods allow analyzing the vulnerability parameters of different coastal zones. While storm surges can nowadays be reproduced accurately, the modeling of coastal flooding is more challenging, particularly when barrier breaches and wave overtopping have to be accounted for. The chronology of past marine floods can be reconstructed combining historical archives and sediment records. Sediment records of past marine floods localized in back barrier depressions are more adequate to reconstruct past flooding chronology. For the two last centuries, quantitative and descriptive historical data can be used to characterize past marine floods. Beyond providing a chronology of events, sediment records combined with geochronology, statistical analysis and climatology, can be used to reconstruct millennial-scale climate variability and enable a better understanding of the possible regional and local long-term trends in storm activity. Sediment records can also reveal forgotten flooding of exceptional intensity, much more intense than those of the last few decades. Sedimentological and historical archives, combined with high-resolution topographic data or numerical hindcast of storms can provide quantitative information and explanations for marine flooding processes. From these approaches, extreme past sea levels height can be determined and are very useful to complete time series provided by the instrumental measurements on shorter time scales. In particular, historical data can improve the determination of the return periods associated with extreme water levels, which are often inaccurate when computed based on instrumental data, due to the presence of gaps and too short time-series. Long-term numerical hindcast of tides and surges can also be used to provide the required time series for statistical analysis. Worst-case scenarios, used to define coastal management plans and strategies, can be obtained from realistic atmospheric settings with different tidal ranges and by shifting the trajectory of storms.
Management of future crises and planning efforts to adapt to marine submersions are optimized by predictions of water levels from hydrodynamic models. Such predictions combined with in situ measurements and analysis of human stakes can be used to define a vulnerability index. Then, the efficiency of adaptation measures can be evaluated with respect to the number of lives that could be potentially saved. Numerical experiments also showed that the realignment of coastal defenses could result in water level reduction up to 1m in the case where large marshes are flooded. Such managed realignment of coastal defenses may constitute a promising adaptation to storm-induced flooding and future sea level rise. From a legal perspective, only a few texts pay specific attention to the risk of marine flooding whether nationally or globally. Recent catastrophic events and their unintended consequences in terms of death and damages have triggered political decisions, like in USA after hurricane Katrina, and in France after catastrophic floods that occurred in 2010.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•QIRN models stable isotope ratios with discrete isotopologues in complex networks.•Applicable to any binary isotope system (13C/12C, 34S/32S, etc.).•Case studies include three bacterial metabolisms, ...Calvin cycle, and prebiotic chemistry.•QIRN reproduces previous models and observed isotope fractionations in nature.•QIRN autonomously builds networks through a graphic user interface.
Natural-abundance stable isotope compositions are powerful tools for understanding complex processes across myriad scientific disciplines. However, quantitative interpretation of these signals often requires equally complex models. Previous stable isotope models have treated isotopic compositions as intrinsic properties of molecules or atoms (e.g. δ13C, 13R, etc.). This has proven to be a computationally efficient but inflexible approach. Here, we present a new isotope modelling software tool that combines computational strategies used in metabolic modeling with an understanding of natural isotope fractionations from the geosciences, called Quantifying Isotopologue Reaction Networks (QIRN, “churn”). QIRN treats isotopic properties as distributions of discrete isotopologues, i.e. molecules with different numbers and distributions of isotopic substitutions. This approach is remarkably generalizable and computationally tractable, enabling models of reaction networks with unprecedented complexity. QIRN parameterizes reactions as rate law equations with distinct isotopologues as the reactants and products. Isotope effects are implemented as small changes to the relevant isotopologues’ rate constants. Running this model forward in time gives the numerical solution for steady state isotopologue abundances. Different subsets of the isotopologue population can then be sampled to quantify numerous isotopic proprieties simultaneously (i.e. compound-specific, site-specific, and multiply-substituted isotope compositions). Furthermore, QIRN can model any physical, chemical or biological process as reversible or irreversible. As such, it incorporates both kinetic and equilibrium isotope effects. It can be readily applied to any isotope system (i.e. C, N, O, etc.), though at present can only track two isotopes of one element at a time. Given its generalizability, QIRN has a diverse range of applications. To demonstrate the flexibility and efficiency of QIRN, we reconstructed previous (intrinsic-property) models of sulfate reduction, abiotic amino acid synthesis, lipid biosynthesis, and photosynthesis. In these examples, QIRN consistently reproduced outputs from prior models and predicted isotopic anomalies that have been measured in nature. With its new approach to isotope modelling, QIRN will expand the potential complexity of modelled reaction networks, help predict isotopic signals that can direct experimental efforts, and provide a more efficient means of modeling emerging isotopic properties such as ‘clumped isotopes’.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•The indoor radiation experiment is carried out for the study of temperature field.•A refined model of the solar temperature field of the composite bridge is established.•The automatic processing of ...shadow occlusion effects is realized.•The simulated data is in good agreement with the experimental values.•The proposed method can realize the temperature analysis of various composite bridges.
The temperature field and its effect are important issues related to the design and construction of bridges. For steel–concrete composite bridges, the huge difference in thermal performance between steel and concrete makes the temperature field distribution and variation more complicated. In this paper, an indoor baking lamp radiation experiment with controllable parameters is carried out on a group of two steel–concrete composite beam specimens for the study of temperature field. The temperature time-history and distribution laws of the specimen during heating and cooling process are observed and analyzed. Furthermore, a refined numerical model of the solar temperature field of the composite bridge is established and verified by the baking lamp radiation experiment. The proposed refined numerical model of the temperature field of the steel–concrete composite bridge realizes the temperature field analysis of various cross-sections of composite bridges and can automatically consider the shielding effect of the flange on the web, providing a useful tool for the modeling of and analysis of the temperature field of composite bridges.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The methodological process for defining the drainage retention capacity of surface layers under conditions of unsteady-state groundwater flow was demonstrated. An artificial neural network analyst ...model was advanced based on the information from the well-tested model HYDRUS-2D/3D. Artificial neural network knowledge is reported as an intermittent to physical-based modeling of subsurface water distribution from trickle emitters. Three options are prospected to create input-output functional relations from information created using a numerical model (HYDRUS-2D). Artificial neural networks are a tool for modeling of non-linear systems in various engineering fields. These networks are effective tools for modeling non-linear systems. Each artificial neural network includes an input layer and an output layer between which there are one or some hidden layers. In each layer, there are one or several processing elements or neurons. The neurons of the input layer are independent variables of the understudy issue and the neurons of the output layer are its dependent variables. An artificial neural system, through exerting weight on inputs and by using an activation function, attempts to achieve a desirable output. In this research, in order to calculate the drain spacing in an unsteady state in a region situated in the northeast of Ahwaz, Iran, with different soil properties and drain spacing, the artificial neural networks have been used. The neurons in the input layer were specific yield, hydraulic conductivity, depth of the impermeable layer, and height of the water table in the middle of the interval between the drains in two-time steps. The neurons in the output layer were drain spacing. The network designed in this research included a hidden layer with four neurons. The distance of drains computed via this method had a good agreement with real values and had a high precision in comparison with other methods. This was done for three types of linear activation functions and hyperbolic and sigmoid tangents. The mean error was 0.1455, 0.092, and 0.0491, respectively.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Alkali-activated binders for concrete composites are emerging as the available low-embodied-carbon alternatives to ordinary Portland cement (OPC). Despite decades of research, the durability of ...alkali-activated concrete remains a concern, especially the issues related to chloride penetration and the potential for chloride-induced corrosion of embedded steel bars. In this study, a multi-phase, multi-component ionic numerical model is developed to investigate the chloride transport in alkali-activated fly ash/slag (AAFS) concretes. The model framework considers the porosity of concrete, the chloride binding, and the electrochemical coupling between multi-species. Based on the proposed model, the parametric studies of a series of influencing factors on both chloride transport and initiation time of reinforcement corrosion are performed and discussed. The results indicate that the slag content and the water to binder ratio are the dominant factors affecting chloride penetration and corrosion initiation time of steel bars in AAFS concretes due to their greater contributions to reduce the porosity, while the aggregate volume fraction presents a limited effect compared with other factors. The transport model proposed in this study brings insights to the prediction of the service life of alkali-activated reinforced concrete structures.
•A multi-phase, multi-species model is developed to investigate the chloride transport behaviour in the binary AAFS system.•The proposed model considers the porosity of concrete, chloride binding and electrochemical coupling between multi-species.•The influence mechanism of relevant factors on both chloride penetration and reinforcement corrosion onset is discussed.•Slag content is proved to be the most important influencing factor on chloride transport in AAFS concretes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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