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Recent studies have started to explore coupled data assimilation (CDA) in coupled ocean-atmosphere models because of the great potential of CDA to improve climate analysis and seamless weather-climate prediction on weekly-to-decad...
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Recent studies have started to explore coupled data assimilation (CDA) in coupled ocean-atmosphere models because of the great potential of CDA to improve climate analysis and seamless weather-climate prediction on weekly-to-decadal time scales in advanced high-resolution coupled models. In this review article, we briefly introduce the concept of CDA before outlining its potential for producing balanced and coherent weather-climate reanalysis and minimizing initial coupling shocks. We then describe approaches to the implementation of CDA and review progress in the development of various CDA methods, notably weakly and strongly coupled data assimilation. We introduce the method of coupled model parameter estimation (PE) within the CDA framework and summarize recent progress. After summarizing the current status of the research and applications of CDA-PE, we discuss the challenges and opportunities in high-resolution CDA-PE and nonlinear CDA-PE methods. Finally, potential solutions are laid out.
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Received for publication 27 April 2007. Coupling physical and geochemical processes within one integrated numerical simulator provides a process-based tool for investigating the mobility of contaminants as affected by changing hyd...
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Received for publication 27 April 2007. Coupling physical and geochemical processes within one integrated numerical simulator provides a process-based tool for investigating the mobility of contaminants as affected by changing hydrologic regimes and geochemical conditions. We review interactions between physical and biogeochemical processes in the vadose zone, and then present a case study demonstrating these complex interactions. A hypothetical application is presented of the HP1 multicomponent transport simulator to predict the transport of two major elements (Ca and P) and one trace element (U) applied annually for 200 yr to a field soil in the form of an inorganic P fertilizer. Interactions of Ca, P, and U with the solid phase are described using cation exchange and surface complexation reactions. Simulations assuming steady-state or transient flow conditions were analyzed in terms of temporal variations of the linear distribution coefficient, Kd, which depends strongly on pH and the composition of the aqueous phase. If the composition of the aqueous phase is constant, adsorption of Ca and U increases with increasing pH. Due to the annual addition of Ca, P, and U, and competition between P and U for sorption sites, the Kd of these elements decreased with time near the soil surface. Deeper in the soil, the Kd of U followed the pH increase because of a lack of competition from P. Because of the combined effects of changing hydrologic and geochemical conditions, the Ca and U distribution coefficients and solute fluxes during the transient simulation exhibited large short-time variations of up to three orders of magnitude.
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This study describes a 29-yr (1981-2009) global ocean surface gravity wave simulation generated by a coupled atmosphere-wave model using NOAA/GFDL's High-Resolution Atmosphere Model (HiRAM) and the WAVEWATCH III surface wave model...
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This study describes a 29-yr (1981-2009) global ocean surface gravity wave simulation generated by a coupled atmosphere-wave model using NOAA/GFDL's High-Resolution Atmosphere Model (HiRAM) and the WAVEWATCH III surface wave model developed and used operationally at NOAA/NCEP. Extensive evaluation of monthly mean significant wave height (SWH) against in situ buoys, satellite altimeter measurements, and the 40-yr ECMWF Re-Analysis (ERA-40) show very good agreements in terms of magnitude, spatial distribution, and scatter. The comparisons with satellite altimeter measurements indicate that the SWH low bias in ERA-40 reanalysis has been improved in these model simulations. The model fields show a strong response to the North Atlantic Oscillation (NAO) in the North Atlantic and the Southern Oscillation index (SOI) in the Pacific Ocean that are well connected with the atmospheric responses. For the NAO in winter, the strongest subpolar wave responses are found near the northern Europe coast and the coast of Labrador rather than in the central-northern Atlantic where the wind response is strongest. Similarly, for the SOI in the Pacific Ocean, the wave responses are strongest in the northern Bering Sea and the Antarctic coast.
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A brief review of the importance of simulation-based engineering and science (including social sciences) is followed by a historic perspective of model-based simulation. Section 2 is on declarative modeling of component systems as...
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A brief review of the importance of simulation-based engineering and science (including social sciences) is followed by a historic perspective of model-based simulation. Section 2 is on declarative modeling of component systems as well as its advantages for self-documentation and for computer-aided checks and coupling. As an example for declarative modeling, General System Theory (GEST) implementor is given. In Sec. 3, basic concepts for coupling of component models, and rules for computer-assisted coupling specification are explained. Section 4 is devoted to possible computerized checks in couplings of declarative models such as: (1) automatic unit checking to avoid meaningless input/output matching at the time of coupling specification, (2) automatic threshold checking to provide warnings and/or to avoid disasters, and (3) automatic unit conversion for convenience of using library models. Section 5 is about several layers of nested couplings for modeling systems of systems. In Sec. 6, two types of variable couplings are discussed: (1) couplings with variable connections (to allow input/output relations of models to depend on time or state conditions) and (2) coupling with variable component models (to allow component (or coupled) models to be switched based on time or state conditions). Section 7 is on the use of multimodels as component models in couplings. Section 8 is on types of inputs and their use in couplings as well as on external inputs to simulation studies. In Sec. 9, conclusions and future work for complex systems are outlined. Especially, the values of simulation systems engineering as well as understanding and avoidance of misunderstanding in cognitive and emotive simulations are stressed. Appendix A is a list of almost 50 types of couplings and Appendix B lists over 50 terms related with couplings in modeling and simulation. To show the richness of "input" concept which is important in specification of input/output relations of component models, Appendix C lists almost 150 types of inputs. Information shared in this article may be useful in developing advanced modeling and simulation software, tools and environments.
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The physical effects used to guide system design are becoming increasingly multidisciplinary. As a result, the undesired design coupling represented by undesired multidisciplinary physical effects is an intrinsic problem of great ...
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The physical effects used to guide system design are becoming increasingly multidisciplinary. As a result, the undesired design coupling represented by undesired multidisciplinary physical effects is an intrinsic problem of great complexity in mechatronics design. However, little attention has been paid to address this issue. In this study, an efficient recognition method is proposed to obtain the undesired physical effects. In view of the importance of flows for the analysis of technical systems and technical processes, a flow-based representation is proposed to model both physical effects and components. Meanwhile, physical semantics is specified by various constraints applied on input/output flows to support physics-based reasoning. According to the representation, the output flows of components can be calculated to obtain flow distributions in the local influence area (LIA) based on interval-based logic to improve the computational efficiency. Within LIAs, undesired physical effects can be recognised by checking the related triggering conditions specified in physical effect knowledge base. A hairdryer example is used to academically demonstrate the proposed method.
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This study explores several types of macroscopic models, by modifying Multiple-Vertical-Line-Element-Model (MVLEM), to represent the coupled concrete shear wall, with different ways of connection to simulate coupling beam. For thi...
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This study explores several types of macroscopic models, by modifying Multiple-Vertical-Line-Element-Model (MVLEM), to represent the coupled concrete shear wall, with different ways of connection to simulate coupling beam. For this purpose, an existing shear wall in which several openings are symmetrically embedded was studied. The wall was analyzed by the microscopic Finite-Element Method (FEM) in ABAQUS. In order to investigate the macroscopic modelling of the mentioned wall, three different macroscopic coupled shear walls, composed of several nonlinear springs, representing flexural and shear behaviors were studied. The main difference among the three walls is in the type of the coupling beam connection used. Hence, three connections were proposed with different stiffnesses. Unlike the connection, the macroscopic coupling beams for the three models were identical based on moment distribution. In order to model the coupling beam, two separate shear walls were considered which were connected to each other from the uppermost part. Responses of the walls under cyclic, monotonic, and dynamic loadings were compared with those of the verified FEM model. The results indicate that the macroscopic wall with moderate connection stiffness has acceptable consistency in terms of static and dynamic responses of the microscopic model.
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The Model Coupling Toolkit (MCT) is a software library for constructing parallel coupled models from individual parallel models. MCT was created to address the challenges of creating a parallel coupler for the Community Climate Sy...
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The Model Coupling Toolkit (MCT) is a software library for constructing parallel coupled models from individual parallel models. MCT was created to address the challenges of creating a parallel coupler for the Community Climate System Model (CCSM). Each of the submodels that make up CCSM is a separate parallel application with its own domain decomposition, running on its own set of processors. This application contains multiple instances of the M x N problem, the problem of transferring data between two parallel programs running on disjoint sets of processors. CCSM also requires efficient data transfer to facilitate its interpolation algorithms. MCT was created as a generalized solution to handle these and other common functions in parallel coupled models. Here we describe MCT's implementation of the data transfer infrastructure needed for a parallel coupled model. The performance of MCT scales satisfactorily as processors are added to the system. However, the types of decompositions used in the submodels can affect performance. MCT's infrastructure provides a flexible and high-performing set of tools for enabling interoperability between parallel applications.
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Coupled modelling is increasingly necessary to make progress in understanding the science of complex physical phenomena and a number of bespoke ('custom') coupled solutions to specific scientific challenges have emerged in recent ...
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Coupled modelling is increasingly necessary to make progress in understanding the science of complex physical phenomena and a number of bespoke ('custom') coupled solutions to specific scientific challenges have emerged in recent years. These coupled models generally consist of some framework code in which individual models are embedded. The framework code promotes the required interoperation of the models to solve the larger problem being addressed. Bespoke solutions limit the ability of scientists to share models and to couple them together flexibly to produce (efficient) implementations to address new problems. This paper presents an approach, GCF, which addresses several of these limitations. Individual model sharing and flexibility in composition and deployment is achieved by imposing some lightweight development rules for single models and capturing information relating to the models themselves, to their composition into coupled models and to their deployment onto computational resources as machine-readable metadata. These metadata can be processed to support the generation of an implementation of the coupled model required by the developer. For example, lean and efficient framework code for the specific coupled model and deployment described by the developer can be generated. Alternatively, GCF-compliant models can be automatically adapted for use within other, existing frameworks. This paper presents the design and implementation of a bespoke framework generator to achieve the former, and the flexibility in the composition of GCF-compliant models is demonstrated.
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The present study investigated nonlinear modeling parameters for reinforced concrete coupling beams. Based on a review of the existing test results of 79 coupling beams, modeling parameters of varying aspect ratios and transverse ...
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The present study investigated nonlinear modeling parameters for reinforced concrete coupling beams. Based on a review of the existing test results of 79 coupling beams, modeling parameters of varying aspect ratios and transverse reinforcement ratios were proposed. First, the effective stiffness and yield deformation were formulated as functions of aspect ratio. Second, the deformation capacity varying with reinforcement details was examined, and its design equation was defined as a function of transverse reinforcement ratio. Third, the energy dissipation ratio to define hysteresis loop under cyclic loading was suggested as a function of aspect ratio and reinforcement details. For verification, the modeling results of load-deformation relations were compared with the existing test results. The predicted load-deformation relations showed good agreement with the test results. Finally, practical applications to computer modeling are discussed.
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Concrete manufactured with desalinated sea sand undergoes carbonation. Consequently, pH decreases and chloride ion (Cl~-) is redistributed, interactively impacting the safety of embedded reinforcements. In this study, a physical m...
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Concrete manufactured with desalinated sea sand undergoes carbonation. Consequently, pH decreases and chloride ion (Cl~-) is redistributed, interactively impacting the safety of embedded reinforcements. In this study, a physical model considering the processes of cement hydration, pore structure formation, substances transport, and chemical reactions is established. Six key indicators, including the characteristics of carbonation degrees and Cl~- distribution, prove the model’s high accuracy. Subsequently, durability-related design suggestions, such as avoiding reinforcement corrosion under the combined impact of carbonation and premixed Cl~- , are implemented. The allowable Cl~- in desalinated sea sand must be not more than 1/3 of the present allowable values. To ensure a 50-year service life of a concrete with a 50-mm-thick reinforcement cover, the water-cement ratios under the influence of the coupling interaction and single carbonation must not exceed 0.28 and 0.36, respectively.
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