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Slab Ocean Component of the Energy Exascale Earth System model (E3SM): Development, Evaluation, and Application to Understanding Earth System Sensitivity

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JOURNAL OF ADVANCES IN modelING EARTH SYSTEMS 2024年第5期16卷

作者： Garuba, Oluwayemi Rasch, Philip J. Leung, L. Ruby Wang, Hailong Hagos, Samson Singh, Balwinder Pacific NorthWest Natl Lab Richland WA 99354 USA

This work describes the implementation and evaluation of the Slab Ocean model component of the Energy Exascale Earth System model version 2 (E3SMv2-SOM) and its application to understanding the climate sensitivity to ocean heat transports (OHTs) and CO2 forcing. E3SMv2-SOM reproduces the baseline climate and Equilibrium Climate Sensitivity (ECS) of the fully coupled E3SMv2 experiments reasonably well, with a pattern correlation close to 1 and a global mean bias of less than 1% of the fully coupled surface temperature and precipitation. Sea ice extent and volume are also well reproduced in the SOM. Consistent with general model behavior, the ECS estimated from the SOM (4.5 K) exceeds the effective climate sensitivity obtained from extrapolation to equilibrium in the fully coupled model (4.0 K). The E3SMv2 baseline climate also shows a large sensitivity to OHT strengths, with a global surface temperature difference of about 4.0 degrees C between high-/low-OHT experiments with prescribed forcings derived from fully coupled experiments with realistic/weak ocean circulation strengths. Similar to their forcing pattern, the surface temperature response occurs mainly over the subpolar regions in both hemispheres. However, the Southern Ocean shows more surface temperature sensitivity to high/low-OHT forcing due to a positive/negative shortwave cloud radiative effect caused by decreases/increases in mid-latitude marine low-level clouds. This large temperature sensitivity also causes an overcompensation between the prescribed OHTs and atmosphere heat transports. The SOM's ECS estimate is also sensitive to the prescribed OHT and the associated baseline climate it is initialized from;the high-OHT ECS is 0.5 K lower than the low-OHT ECS. The implementation and evaluation of the Slab Ocean model (SOM) in the Energy Exascale Earth System model version 2 (E3SMv2) is described in this study. The SOM is evaluated by comparing its climate simulation to that of the full version of the m

关键词： model verification and validation hierarchical climate modeling global climate models ocean/atmosphere interactions climate sensitivity clouds and cloud feedbacks

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Reduced Three-Dimensional model for Cold Rolling Simulation of Aluminium Alloys 14th

Reduced Three-Dimensional Model for Cold Rolling Simulation ...

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14th International Conference on Numerical Methods in Industrial Forming Processes (NUMIFORM)

作者： Pachnek, Florian Simon, Peter Zeman, Klaus AMAG Rolling GmbH Lamprechtshausener Str 61 A-5282 Ranshofen Austria Johannes Kepler Univ Linz Inst Mechatron Design & Prod Altenberger Str 69 A-4040 Linz Austria

ISBN: (纸本)9783031580086;9783031580062;9783031580055

Mathematical modelling and computational analyses allow to deepen the understanding of manufacturing processes, to ensure high product quality and to reduce experimental efforts for the optimization of product properties and production processes. In order to predict the evolution of flat rolled aluminium product properties and their interdependence with process parameters, virtual representations of the entire process chain including process models of hot rolling, coiling, and cold rolling operations are highly beneficial. Starting from the solid foundation of a comprehensively validated 3D model of the hot rolling process of various aluminium alloys, the present work presents a 3D thermo-mechanical cold rolling simulation model using the commercial finite element code LS-DYNA. The material behaviour is considered by means of a user defined material model according to a modified dislocation density based flow model. The calculated microstructural and deformation history of the hot rolled strip is considered as input for the developed cold rolling model allowing for seamless prediction of product properties. For numerical studies, a modular modelling approach is pursued, comprising tailor-made simplifications depending on actual applications and research problems. For time efficient multi-pass simulations in an industrial environment, a reduced model with plane strain conditions is derived that extends the predictability of product properties and process parameters from hot rolling over coiling to cold rolling. Simulation results and computational costs are compared with detailed 3D models. Strip tensions can be adjusted showing the expected effects on roll separating forces and minimum rolled thickness. To ensure the desired strip tensions in the numerical model, a sensor-based control of strip tensions is implemented. For validation purposes, measured rolling forces from industrial pass schedules for 6xxx series alloys are compared against simulation results.

关键词： Multi-pass rolling of aluminium alloys Hot and cold rolling simulation model verification and validation

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Critical Comparison of Phase-Field, Peridynamics, and Crack Band model M7 in Light of Gap Test and Classical Fracture Tests

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JOURNAL OF APPLIED MECHANICS-TRANSACTIONS OF THE ASME 2022年第6期89卷 061008页

作者： Bazant, Zdenek P. Nguyen, Hoang T. Donmez, A. Abdullah Northwestern Univ Civil & Mech Engn & Mat Sci Evanston IL 60208 USA Northwestern Univ Evanston IL 60208 USA Istanbul Tech Univ Dept Civil Engn TR-34467 Istanbul Turkey

The recently conceived gap test and its simulation revealed that the fracture energy G(f) (or K-c, J(cr)) of concrete, plastic-hardening metals, composites, and probably most materials can change by +/- 100%, depending on the crack-parallel stresses sigma(xx), sigma(zz), and their history. Therefore, one must consider not only a finite length but also a finite width of the fracture process zone, along with its tensorial damage behavior. The data from this test, along with ten other classical tests important for fracture problems (nine on concrete, one on sandstone), are optimally fitted to evaluate the performance of the state-of-art phase-field, peridynamic, and crack band models. Thanks to its realistic boundary and crack face conditions as well as its tensorial nature, the crack band model, combined with the micro-plane damage constitutive law in its latest version M7, is found to fit all data well. On the contrary, the phase-field models perform poorly. Peridynamic models (both bond based and state based) perform even worse. The recent correction in the bond-associated deformation gradient helps to improve the predictions in some experiments, but not all. This confirms the previous strictly theoretical critique (JAM 2016), which showed that peridynamics of all kinds suffers from several conceptual faults: (1) It implies a lattice microstructure;(2) its particle-skipping interactions are a fiction;(4) it ignores shear-resisted particle rotations (which are what lends the lattice discrete particle model (LDPM) its superior performance);(3) its representation of the boundaries, especially the crack and fracture process zone faces, is physically unrealistic;and (5) it cannot reproduce the transitional size effect-a quintessential characteristic of quasibrittleness. The misleading practice of "verifying" a model with only one or two simple tests matchable by many different models, or showcasing an ad hoc improvement for one type of test while ignoring misfits of othe

关键词： computational mechanics constitutive modeling of materials model verification and validation structural failure fracture mechanics boundary conditions modes I, II, and III size effect quasibrittle materials concrete fracture tests vertex effect peridynamics phase-field model microplane model

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Interactively Assessing Disentanglement in GANs

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COMPUTER GRAPHICS FORUM 2022年第3期41卷 85-95页

作者： Jeong, Sangwon Liu, Shusen Berger, Matthew Vanderbilt Univ 221 Kirkland Hall Nashville TN 37235 USA Lawrence Livermore Natl Lab Livermore CA 94550 USA

Generative adversarial networks (GAN) have witnessed tremendous growth in recent years, demonstrating wide applicability in many domains. However, GANs remain notoriously difficult for people to interpret, particularly for modern GANs capable of generating photo-realistic imagery. In this work we contribute a visual analytics approach for GAN interpretability, where we focus on the analysis and visualization of GAN disentanglement. Disentanglement is concerned with the ability to control content produced by a GAN along a small number of distinct, yet semantic, factors of variation. The goal of our approach is to shed insight on GAN disentanglement, above and beyond coarse summaries, instead permitting a deeper analysis of the data distribution modeled by a GAN. Our visualization allows one to assess a single factor of variation in terms of groupings and trends in the data distribution, where our analysis seeks to relate the learned representation space of GANs with attribute-based semantic scoring of images produced by GANs. Through use-cases, we show that our visualization is effective in assessing disentanglement, allowing one to quickly recognize a factor of variation and its overall quality. In addition, we show how our approach can highlight potential dataset biases learned by GANs.

关键词： CCS Concepts • Computing methodologies → Artificial intelligence model verification and validation

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modelling crystallization: When the normal growth velocity depends on the supersaturation

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JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS 2023年 181卷

作者： Ivanov, V. V. Tielemann, C. Avramova, K. Reinsch, S. Tonchev, V. Sofia Univ Fac Phys Sofia 1164 Bulgaria ASML Berlin GmbH D-12347 Berlin Germany Bundesanstalt Materialforsch & Prufung BAM D-12205 Berlin Germany Bulgarian Acad Sci Inst Phys Chem Sofia 1113 Bulgaria

The crystallization proceeds by the advance of the crystal faces into the disordered phase at the expense of the material excess, the supersaturation. Using a conservation constraint for the transformation ratio & alpha;& ISIN;[0,1] as complementing the rescaled supersaturation to 1 and a kinetic law for the normal growth velocity as function of the supersaturation raised to power g, the growth order, we derive an equation for the rate of transformation d & alpha;/ dt. We integrate it for the six combinations of the three spatial dimensions D = 1, 2, 3 and the two canonical values of g = 1, 2 towards obtaining expressions for & alpha;Dg. The same equation, with g = 1 and D = n (n is the so called Avrami exponent) is obtained when taking only the linear in & alpha;term from the Taylor's expansion around & alpha;= 0 of the model equation of Johnson-Mehl-Avrami-Kolmogorov (JMAK). We verify our model by fitting datasets of & alpha;21 and & alpha;31 (from & alpha;= 0 to & alpha;upper = 0.999) with JMAK to obtain from the fit n = 1.725, 2.43, resp. We show further how the values of n depend on the value of & alpha;upper to which the fit is performed starting always from 0. Towards building a validation protocol, we start with validating & alpha;21 with published results.

关键词： Crystallization Supersaturation Growth kinetics Growth rate model verification and validation Johnson-Mehl-Avrami-Kolmogorov (JMAK) model Dimensional analysis (DA)

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verification and validation of software process simulation models: A systematic mapping study

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JOURNAL OF SOFTWARE-EVOLUTION AND PROCESS 2023年第6期36卷

作者： Li, Yue Zhang, He Liu, Bohan Dong, Liming Gong, Haojie Rong, Guoping Nanjing Univ Software Inst State Key Lab Novel Software Technol Nanjing Jiangsu Peoples R China

Software process simulation models (SPSMs) that are based on descriptive process models offer the executability that can demonstrate dynamic changes of software processes over time. verification and validation (V&V) is critical in SPSMs for guaranteeing the quality and reliability of models. V&V of dynamic software process models is more complex and challenging than for static software process models. This work systematically summarizes and maps V&V studies in SPSM to provide guidelines for future research and practice. Specifically, this study aims at identifying the focus of research on V&V, the methods used for V&V, and how to implement V&V of SPSMs in software engineering research. We conducted a systematic mapping study on studies of SPSMs that report on their V&V activities. Under the guidance of a V&V meta-model for SPSMs, we study four research questions about V&V process. We identified 107 primary studies from a pool of 313 papers on SPSMs until 2021. There are two main results of our study. The first one presents the relationship between quality aspects of SPSMs and the V&V methods to assure them. The second result reveals the relationships among the modeling process, three modeling steps, five quality aspects, and 10 V&V methods. Generally, researchers do not pay sufficient attention to V&V, as 65.8% ( (313-107)/313$$ \left(313-107\right)/313 $$) failed to mention or elaborate on their V&V process. We systematically summarize and map the state-of-the-art V&V research in software process modeling field to support modelers' practice and improve their V&V process.

关键词： model verification and validation process simulation software process modeling systematic mapping study

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Impact of consistency between modeling detail and physical uncertainties on severe accident predictions

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NUCLEAR ENGINEERING AND DESIGN 2021年 384卷

作者： Podowski, Michael Z. Podowski, Raf M. Kim, Dong Ha Bae, Jun Ho Son, Dong Gun Rensselaer Polytech Inst Troy NY 12180 USA Podowski Engn Consulting Clifton Pk NY USA Hanyang Univ Seoul South Korea Korea Atom Energy Res Inst Daejeon South Korea

The complexity of phenomena occurring during severe accidents in nuclear reactors, combined with a limited amount of experimental evidence, do not allow for formulating detailed reliable models or making highly accurate predictions of accident progression. Thus, the modeling consistency and a proper understanding of the uncertainties associated with the results of any computer simulations, including those caused by the imperfection and inherent limitations of the available experimental data used in model validation, are critical for improving accident mitigation capabilities and for enhancing the safety of current and future generations of nuclear reactors. The objective of this paper is to give an overview of selected issues illustrating the importance of: (a) identifying the dominant phenomena governing the progression of core meltdown accidents, and (b) formulating models which are consistent with our understanding of the underlying physics and chemistry and of the increasing level of randomness as the accident progresses. The results used as examples, in particular those pertaining to the research performed by the authors and their collaborators, have been obtained over past several years and documented in a several reports (in particular, in the USNRC NUREG series), but have never been included in copy-righted publications. The sources of any other experimental data used in the discussion of specific coupled experimental/modeling issues (typically, also reports of various agencies or labs) are clearly identified in the text. Since some of the examples include recent unpublished results of computer simulations performed using updated versions of the models which have already been published in other journals, only brief information about such models is presently shown, assuming that the reader can find details in the corresponding references.

关键词： Core meltdown accidents Experimental and modeling uncertainties model verification and validation Importance of modeling consistency Accident mitigation

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Adapting the MPAS Dynamical Core for Applications Extending Into the Thermosphere

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JOURNAL OF ADVANCES IN modelING EARTH SYSTEMS 2021年第9期13卷

作者： Klemp, J. B. Skamarock, W. C. Natl Ctr Atmospher Res POB 3000 Boulder CO 80307 USA

To extend the nonhydrostatic global model for Prediction Across Scales (MPAS) for deep-atmosphere (geospace) applications, we have modified the model equations and numerics to include variable atmospheric composition and (potentially large) molecular viscosity and thermal conductivity. The split-explicit numerical integration techniques in MPAS remain stable in idealized test cases for atmospheric domains extending into the upper thermosphere and continue to provide an efficient numerical framework for nonhydrostatic simulations. Variations in the atmospheric constituents influence the dynamical equations by altering the heat capacity and ideal gas constants. These feedbacks require little alteration of the dynamical equations although our testing reveals that the amplitude of disturbances may be sensitive to even small variations in the thermodynamic coefficients. Although the potential temperature is no longer formally conserved for adiabatic flow, it remains effective as a prognostic thermodynamic variable in the model equations. Molecular viscosity and thermal conductivity are dominant influences in the upper thermosphere and are represented implicitly in the model numerics. Because of the large magnitude of these terms, their treatment, though stable, may significantly under represent the true magnitude of their damping effects. Further consideration of these deep-atmosphere extensions to MPAS will be explored in more realistic simulations of thermospheric dynamics.

关键词： idealized model modeling model verification and validation numerical solutions numerical approximations and analyses

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Advanced Hazard Analysis and Risk Assessment in the ISO 26262 Functional Safety Standard Using Rigorous Simulation 9th

Advanced Hazard Analysis and Risk Assessment in the ISO 2626...

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9th International Workshop on model-Based Design of Cyber Physical Systems (CyPhy) / 15th International Workshop on Embedded and Cyber-Physical Systems Education (WESE)

作者： Duracz, Adam Aljarbouh, Ayman Bartha, Ferenc A. Masood, Jawad Philippsen, Roland Eriksson, Henrik Duracz, Jan Xu, Fei Zeng, Yingfu Grante, Christian Univ Grenoble Alpes GIPSA Lab Grenoble INP Grenoble France Halmstad Univ Sch Informat Technol Halmstad Sweden Rice Univ Dept Comp Sci Houston TX USA SP Tech Res Inst Sweden Dependable Syst Boras Sweden AB Volvo Grp Trucks Technol Gothenburg Sweden

ISBN: (纸本)9783030411312;9783030411305

With the increasing level of automation in road vehicles, the traditional workhorse of safety assessment, namely, physical testing, is no longer adequate as the sole means of ensuring safety. A standard safety assessment benchmark is to evaluate the behavior of a new design in the context of a risk-exposing test scenario. Manual or computerized analysis of the behavior of such systems is challenging because of the presence of non-linear physical dynamics, computational components, and impacts. In this paper, we study the utility of a new technology called rigorous simulation for addressing this problem. Rigorous simulation aims to combine some of the benefits of traditional simulation methods with those of traditional analytical methods such as symbolic algebra. We develop and analyze in detail a case study involving an Intersection Collision Avoidance (ICA) test scenario using the hazard analysis techniques prescribed in the ISO 26262 functional safety standard. We show that it is possible to formally model and rigorously simulate the test scenario to produce informative results about the severity of collisions. The work presented in this paper demonstrates that rigorous simulation can handle models of non-trivial complexity. The work also highlights the practical challenges encountered in using it.

关键词： Rigorous simulation model verification and validation Domain specific languages ISO 26262 hazard analysis Validated numerics Interval arithmetic Safety testing model-based testing

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A discrete source model of powder bed fusion additive manufacturing thermal history

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ADDITIVE MANUFACTURING 2019年 25卷 485-498页

作者： Schwalbach, Edwin J. Donegan, Sean P. Chapman, Michael G. Chaput, Kevin J. Groeber, Michael A. US Air Force Res Lab Mat & Mfg Directorate Wright Patterson AFB OH 45433 USA UES Inc Beavercreek OH 45432 USA Ohio State Univ Dept Integrated Syst Engn Columbus OH 43210 USA

Significant attention has been focused on modeling of metallic additive manufacturing (AM) processes, with the initial aim of predicting local thermal history, and ultimately structure and properties. Existing models range greatly in physical complexity and computational cost, and the implications of various simplifying assumption often go unassessed. In the present work, we first formulate a fast acting Discrete Source model (DSM) capable of handling the complex processing often encountered in metal powder bed fusion AM. We then assess implications of the source representation, details of the numeric implementation, as well as effects of boundary conditions and thermophysical parameters. We verify the DSM implementation against simple numerical thermal predictions, calibrate it with single track deposit experiments, validate outputs against multitrack deposits, and finally quantify the scaling performance. The DSM is an effective means of quickly generating an estimate of the local thermal history induced by complex scan strategies when combined with arbitrary component geometry. While a number of approximations limit its quantitative accuracy, the inexpensive nature and ability to treat complex processing plans suggests it will be useful for screening and identification of regions experiencing anomalous thermal history. Such a capability is necessary to direct usage of higher fidelity, more expensive models and experimental resources.

关键词： Selective laser melting Powder bed fusion Thermal modeling model verification and validation

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