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All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Evaluation of Life History Diversity, Habitat Connectivity, and Survival Benefits Associated with Habitat Restoration Actions in the Lower Columbia River and Estuary, Annual Report 2010

This report describes the 2010 research conducted under the U.S. Army Corps of Engineers (USACE) project EST-P-09-1, titled Evaluation of Life History Diversity, Habitat Connectivity, and Survival Benefits Associated with Habitat Restoration Actions in the Lower Columbia River and Estuary, and known as the 'Salmon Benefits' study. The primary goal of the study is to establish scientific methods to quantify habitat restoration benefits to listed salmon and trout in the lower Columbia River and estuary (LCRE) in three required areas: habitat connectivity, early life history diversity, and survival (Figure ES.1). The general study approach was to first evaluate the state of the science regarding the ability to quantify benefits to listed salmon and trout from habitat restoration actions in the LCRE in the 2009 project year, and then, if feasible, in subsequent project years to develop quantitative indices of habitat connectivity, early life history diversity, and survival. Based on the 2009 literature review, the following definitions are used in this study. Habitat connectivity is defined as a landscape descriptor concerning the ability of organisms to move among habitat patches, including the spatial arrangement of habitats (structural connectivity) and how the perception and behavior of salmon affect the potential for movement among habitats (functional connectivity). Life history is defined as the combination of traits exhibited by an organism throughout its life cycle, and for the purposes of this investigation, a life history strategy refers to the body size and temporal patterns of estuarine usage exhibited by migrating juvenile salmon. Survival is defined as the probability of fish remaining alive over a defined amount of space and/or time. The objectives of the 4-year study are as follows: (1) develop and test a quantitative index of juvenile salmon habitat connectivity in the LCRE incorporating structural, functional, and hydrologic components; (2) develop and test a quantitative index of the early life history diversity of juvenile salmon in the LCRE; (3) assess and, if feasible, develop and test a quantitative index of the survival benefits of tidal wetland habitat restoration (hydrologic reconnection) in the LCRE; and (4) synthesize the results of investigations into the indices for habitat connectivity, early life history diversity, and survival benefits.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1998

This New Ocean: A History of Project Mercury

When Congress created the National Aeronautics and Space Administration (NASA) in 1958, it charged NASA with the responsibility "to contribute materially to . . . the expansion of human knowledge of phenomena in the atmosphere and space" and "provide for the widest practicable and appropriate dissemination of information concerning its activities and the results thereof." NASA wisely interpreted this mandate to include responsibility for documenting the epochal progress of which it is the focus. The result has been the development of a historical program by NASA as unprecedented as the task of extending man's mobility beyond his planet. This volume is not only NASA's accounting of its obligation to disseminate information to our current generation of Americans. It also fulfills, as do all of NASA's future-oriented scientific-technological activities, the further obligation to document the present as the heritage of the future. The wide-ranging NASA history program includes chronicles of day-to-day space activities; specialized studies of particular fields within space science and technology; accounts of NASA's efforts in organization and management, where its innovations, while less known to the public than its more spectacular space shots, have also been of great significance; narratives of the growth and expansion of the space centers throughout the country, which represent in microcosm many aspects of NASA's total effort; program histories, tracing the successes- and failures- of the various projects that mark man's progress into the Space Age; and a history of NASA itself, incorporating in general terms the major problems and challenges, and the responses thereto, of our entire civilian space effort. The volume presented here is a program history, the first in a series telling of NASA's pioneering steps into the Space Age. It deals with the first American manned-spaceflight program: Project Mercury. Although some academicians might protest that this is "official" history, it is official only in the fact that it has been prepared and published with the support and cooperation of NASA. It is not "official" history in the sense of presenting a point of view supposedly that of NASA officialdom-if anyone could determine what the "point of view" of such a complex organism might be. Certainly, the authors were allowed to pursue their task with the fullest freedom and in accordance with the highest scholarly standards of the history profession.

Swenson, Loyd S., Jr.↗
NASA NTRS2000

The Geologic History of Mars: An Astrobiology Perspective

Fourteen SNC meteorites contain information which must be incorporated with recent spaceflight data for developing Mars' geologic history. SNCs have crystallization ages of 4500 to 160 m.y. Tle oldest meteorite ALH84001 contains information on the Noachian period of Mars' history. There are no meteorites from the Hesperian period and the remaining 13 meteorites fall into two age groups within the Amazonian: The nakhlites around 1300 m.y. and the shergottites between 800-160 m.y. Oxygen isotopic analysis of Martian samples shows two distinct O2 reservoirs throughout Martian history indicating late additions of volatiles and a lack of plate tectonics prior to 3.9 Gy. Evidence for percolation of aqueous brines through impact-produced fractures in the rocky surface is contained in the 3.9 Gy-old ALH84001 carbonate deposits. These carbonates precipitated at approx. 100 C. At this time life had already evolved on Earth. Early Mars could have hosted life similar to the bacteria that inhabited early Earth. Potential microorganisms could have been transported into fractures by carbonate-bearing waters and their remains could have become incorporated into the precipitated carbonate. Since Mars had a weak magnetic field at this time, it can be hypothesized that some of the Martian microorganisms may have been similar to terrestrial magnetotactic bacteria. Over geologic time episodic cratering, and tectonic events have occurred on Mars along with the periodic release of subsurface waters which may have produced clays within SNC meteorites. The geochemical data contained within SNC meteorites complements previous observational data and the recent Mars Global Surveyor data to provide a geological and environmental history which spans almost the entire lifespan on Mars. One of the outstanding features of this model is the possible creation of an early (about 4 Gy) volatile reservoir distinct from the outgassed Mars volatiles, and the persistence of this reservoir throughout most, if not all of subsequent Mars' history. Within the framework of this history a potential scenario for a possible record of living organisms is provided by suggestive structures and organic signatures trapped within secondary mineral deposits and alteration features of some SNC meteorites. Tracing the differences in oxygen isotopic compositions within Martian components allows us to gain insight in the history of Mars.

Gibson, Everett K.↗
NASA NTRS2002

KSC History Project

The 2002 NASA/ASEE KSC History Project focused on a series of seven history initiatives designed to acquire, preserve, and interpret the history of Kennedy Space Center. These seven projects included the co-authoring of Voices From the Cape, historical work with NASA historian Roger Launius, the completion of a series of oral histories with key KSC personnel, a monograph on Public Affairs, the development of a Historical Concept Map (CMap) for history knowledge preservation, advice on KSC history database and web interface capabilities, the development of a KSC oral history program and guidelines of training and collection, and the development of collaborative relationships between Kennedy Space Center, the University of West Florida, and the University of Central Florida.

Moore, Patrick K.↗
NASA NTRS2003

KSC History Project

The 2003 NASA/ASEE KSC History Project focused on a series of six history initiatives designed to acquire, preserve, and interpret the history of Kennedy Space Center. These six projects included the completion of Voices From the Cape, historical work co-authored with NASA historian Roger Launius, the completion of a series of oral histories with key KSC personnel, expansion of monograph on Public Affairs into two comprehensive pieces on KSC press operations and KSC visitor operations, the expansion of KSC Historical Concept Maps (Cmap) for history knowledge preservation, the expansion of the KSC oral history program through the administration of an oral history workshop for KSC-based practitioners, and the continued collaborative relationships between Kennedy Space Center, the University of West Florida, the University of Central Florida and other institutions including the University of Louisiana at Lafayette.

Moore, Patrick K.↗
NASA NTRS2010

The Formation and Evolution of Tessera and Insights into the Beginning of Recorded History on Venus: Geology of the Fortuna Tessera Quadrangle (V-2)

Today, and throughout its recorded history, Venus can be classified as a "one-plate planet." The observable geological record of the planet comprises only the last 1/4 or less of its overall geologic history. As shown by many authors, it started with intensive deformation in broad regions to form tessera [1-6] during the Fortunian period of history [7]. The period of tessera formation quickly changed to numerous zonal deformational belts of ridges and grooves that were followed by emplacement of vast volcanic plains (shield plains, regional plains) [7,8]. During the final epoch of the geologic history of Venus, large but isolated centers of volcanism formed extensive fields of lavas, with tectonics concentrated within fewer very prominent rift zones [8,9]. The observable changes in intensity and character of volcanism and tectonics suggest progressive changes from thin lithosphere early in the geologic history to thick lithosphere during later epochs [6,10]. We have little idea of the character of the first 3/4 of Venus' history. So, what does the earliest period of recorded history tell us about the transition from the Pre-Fortunian to the Fortunian period and what insight does this give us into this earlier period?

Head, J. W.↗
DOE OSTI2020

Reinforcement learning based automated history matching for improved hydrocarbon production forecast

History matching aims to find a numerical reservoir model that can be used to predict the reservoir performance. An engineer and model calibration (data inversion) method are required to adjust various parameters/properties of the numerical model in order to match the reservoir production history. In this study, we develop deep neural networks within the reinforcement learning framework to achieve automated history matching that will reduce engineers’ efforts, human bias, automatically and intelligently explore the parameter space, and remove the need of large set of labeled training data. To that end, a fast-marching-based reservoir simulator is encapsulated as an environment for the proposed reinforcement learning. The deep neural-network-based learning agent interacts with the reservoir simulator within reinforcement learning framework to achieve the automated history matching. Reinforcement learning techniques, such as discrete Deep Q Network and continuous Deep Deterministic Policy Gradients, are used toth, used to train the learning agents. The continuous actions enable the Deep Deterministic Policy Gradients to explore more states at each iteration in a a learning episode; consequently, a better history matching is achieved using this algorithm as compared to Deep Q Network. For simplified dual-target composite reservoir models, the best history-matching performances of the discrete and continuous learning methods in terms of normalized root mean square errors are 0.0447 and 0.0038, respectively. Furthermore, our study shows that continuous action space achieved by the deep deterministic policy gradient drastically outperforms deep Q network.

42 ENGINEERING↗
DOE OSTI2016

THE HISTORY OF TIDAL DISRUPTION EVENTS IN GALACTIC NUCLEI

The tidal disruption of a star by a massive black hole (MBH) is thought to produce a transient luminous event. Such tidal disruption events (TDEs) may play an important role in the detection and characterization of MBHs, and in probing the properties and dynamics of their nuclear stellar cluster (NSC) hosts. Previous studies estimated the recent rates of TDEs in the local universe. However, the long-term evolution of the rates throughout the history of the universe has been little explored. Here we consider TDE history, using evolutionary models for the evolution of galactic nuclei. We use a 1D Fokker–Planck approach to explore the evolution of MBH-hosting NSCs, and obtain the disruption rates of stars during their evolution. We complement these with an analysis of TDE history based on N -body simulation data, and find them to be comparable. We consider NSCs that are built up from close-in star formation (SF) or from far-out SF/cluster-dispersal, a few pc from the MBH. We also explore cases where primordial NSCs exist and later evolve through additional SF/cluster-dispersal processes. We study the dependence of the TDE history on the type of galaxy, as well as the dependence on the MBH mass. These provide several scenarios, with a continuous increase of the TDE rates over time for cases of far-out SF and a more complex behavior for the close-in SF cases. Finally, we integrate the TDE histories of the various scenarios to provide a total TDE history of the universe, which can be potentially probed with future large surveys (e.g., LSST).

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1989

Fatigue loading history reconstruction based on the rain-flow technique

Methods are considered for reducing a non-random fatigue loading history to a concise description and then for reconstructing a time history similar to the original. In particular, three methods of reconstruction based on a rain-flow cycle counting matrix are presented. A rain-flow matrix consists of the numbers of cycles at various peak and valley combinations. Two methods are based on a two dimensional rain-flow matrix, and the third on a three dimensional rain-flow matrix. Histories reconstructed by any of these methods produce a rain-flow matrix identical to that of the original history, and as a result the resulting time history is expected to produce a fatigue life similar to that for the original. The procedures described allow lengthy loading histories to be stored in compact form.

Khosrovaneh, A. K.↗
NASA NTRS1990

Fatigue loading history reconstruction based on the rainflow technique

Methods are considered of reducing a non-random fatigue loading history to a concise description and then of reconstructing a time history similar to the original. In particular, three methods of reconstruction based on a rainflow cycle counting matrix are presented. A rainflow matrix consists of the numbers of cycles at various peak and valley combinations. Two methods are based on a two-dimensional rainflow matrix, and the third on a three-dimensional rainflow matrix. Histories reconstructed by any of these methods produce a rainflow matrix identical to that of the original history, and the resulting time history is expected to produce a fatigue life similar to that for the original. The procedures described allow lengthy loading histories to be stored in compact form.

Khosrovaneh, A. K.↗
DOE OSTI2015

On the influence of the power plant operational history on the inventory and the uncertainties of radionuclides relevant for the final disposal of PWR spent fuel - 15149

A mandatory requisite for official granting safe final disposal approval of SNF is the comprehensive specification and declaration of the nuclear inventory in SNF by the NPP-operators. The whole radiochemical characterization of each spent fuel assembly hides many difficulties such as very high radiation burden, destruction method, the inhomogeneous burn-up of fuel assembly, very high cost. Thus, non-destructive characterization is usually applied on industrial scale. In this case only several nuclides can be measured, and the rest is calculated using simulations and typical irradiation history. Like any other German rad-waste acceptance requirements all these declarations will have to be checked and verified by an independent inspector. In this verification process not only values of radionuclide (RN) activities are important, but also their uncertainties. The simple simulation using burn-up calculations based on typical and generic reactor operational parameters do not answer the question about possible uncertainties observed in real reactor operations. At the same time, the details of irradiation history are often unknown, which complicates the assessment of declared RN inventories. Therefore, the development of dedicated generic proof tools, which can be applied to different types of waste, often of unknown origin and history is worth a serious consideration. Here, we have compiled a set of burn-up calculations considering the operational history of 339 published or anonymized real PWR fuel assemblies. This gives us the possibility to calculate the realistic variation or spectrum of RN inventories. These histories were used as a basis for 'SRP analysis', to provide information about the range of the values of the associated secondary reactor parameters (SRP's), i.e. initial enrichment (IE), specific power (SP), irradiation time (IT), downtime (DT), boric acid concentration (BA), moderator and fuel density (MD and FD) and temperatures (MT and MT) used as input parameters for the simulation models. Then, burn-up calculation codes provide the anticipated results for the entire nuclear inventory such as characteristic activity values and the corresponding minimum and maximum limits as a function of the fuel burn-up. These results are being validated with the experimental data from various publications and the online database - SFCOMPO and subsequently transferred and summarized into our own database. Ultimately, this database will provide the basis of proof tools for the operator independent verification of the declared nuclear inventories for the quality and safety assessment of a radioactive waste compound and bounding values for certain RN as a function of burn-up. The RN inventory can hence be verified without taking credit of the whole of the operational history of the SNF. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

Prevalence of Americans reporting a family history of cancer indicative of increased cancer risk: Estimates from the 2015 National Health Interview Survey

The collection and evaluation of family health history in a clinical setting presents an opportunity to discuss cancer risk, tailor cancer screening recommendations, and identify people with an increased risk of carrying a pathogenic variant who may benefit from referral to genetic counseling and testing. National recommendations for breast and colorectal cancer screening indicate that men and women who have a first-degree relative affected with these types of cancers may benefit from talking to a healthcare provider about starting screening at an earlier age and other options for cancer prevention. The prevalence of reporting a first-degree relative who had cancer was assessed among adult respondents of the 2015 National Health Interview Survey who had never had cancer themselves (n = 27,999). We found 35.6% of adults reported having at least one first-degree relative with cancer at any site. Significant differences in reporting a family history of cancer were observed by sex, age, race/ethnicity, educational attainment, and census region. Nearly 5% of women under age 50 and 2.5% of adults under age 50 had at least one first-degree relative with breast cancer or colorectal cancer, respectively. We estimated that 5.8% of women had a family history of breast or ovarian cancer that may indicate increased genetic risk. A third of U.S. adults who have never had cancer report a family history of cancer in a first-degree relative. Furthermore, this finding underscores the importance of using family history to inform discussions about cancer risk and screening options between healthcare providers and their patients.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Life history strategies among soil bacteria—dichotomy for few, continuum for many

Abstract Study of life history strategies may help predict the performance of microorganisms in nature by organizing the complexity of microbial communities into groups of organisms with similar strategies. Here, we tested the extent that one common application of life history theory, the copiotroph-oligotroph framework, could predict the relative population growth rate of bacterial taxa in soils from four different ecosystems. We measured the change of in situ relative growth rate to added glucose and ammonium using both 18O–H2O and 13C quantitative stable isotope probing to test whether bacterial taxa sorted into copiotrophic and oligotrophic groups. We saw considerable overlap in nutrient responses across most bacteria regardless of phyla, with many taxa growing slowly and few taxa that grew quickly. To define plausible life history boundaries based on in situ relative growth rates, we applied Gaussian mixture models to organisms’ joint 18O–13C signatures and found that across experimental replicates, few taxa could consistently be assigned as copiotrophs, despite their potential for fast growth. When life history classifications were assigned based on average relative growth rate at varying taxonomic levels, finer resolutions (e.g., genus level) were significantly more effective in capturing changes in nutrient response than broad taxonomic resolution (e.g., phylum level). Our results demonstrate the difficulty in generalizing bacterial life history strategies to broad lineages, and even to single organisms across a range of soils and experimental conditions. We conclude that there is a continued need for the direct measurement of microbial communities in soil to advance ecologically realistic frameworks.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Effects of incomplete residential histories on studies of environmental exposure with application to childhood leukaemia and background radiation

Highlights: • Residential exposures are most important for many environmental carcinogens. • Direct measurement in all occupied homes is the gold standard but may be impractical. • About half of cases of childhood cancer have not moved between birth and diagnosis. • Most house movements are short-range; exposures in successive houses are correlated. • Analyses using exposure estimation from a single address are informative. When evaluating environmental exposures, residential exposures are often most relevant. In most countries, it is impossible to establish full residential histories. In recent publications, childhood leukaemia and background radiation have been studied with and without full residential histories. This paper investigates the consequences of lacking such full data. Data from a nationwide Finnish Case-Control study of Childhood Leukaemia and gamma rays were analysed. This included 1093 children diagnosed with leukaemia in Finland in 1990–2011. Each case was matched by gender and year of birth to three controls. Full residential histories were available. The dose estimates were based on outdoor background radiation measurements. The indoor dose rates were obtained with a dwelling type specific conversion coefficient and the individual time-weighted mean red bone marrow dose rates were calculated using age-specific indoor occupancy and the age and gender of the child. Radiation from Chernobyl fallout was included and a 2-year latency period assumed. The median separation between successive dwellings was 3.4 km and median difference in red bone marrow dose 2.9 nSv/h. The Pearson correlation between the indoor red bone marrow dose rates of successive dwellings was 0.62 (95% CI 0.60, 0.64). The odds ratio for a 10 nSv/h increase in dose rate with full residential histories was 1.01 (95% CI 0.97, 1.05). Similar odds ratios were calculated with dose rates based on only the first dwelling (1.02, 95% CI 0.99, 1.05) and only the last dwelling (1.00, 95% CI 0.98, 1.03) and for subjects who had lived only in a single dwelling (1.05, 95% CI 0.98, 1.10). Knowledge of full residential histories would always be the option of choice. However, due to the strong correlation between exposure estimates in successive dwellings and the uncertainty about the most relevant exposure period, estimation of overall exposure level from a single address is also informative. Error in dose estimation is likely to cause some degree of classical measurement error resulting in bias towards the null.

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTAN↗
DOE OSTI2021

A note on thermal history kernel for unsteady heat transfer of a spherical particle

When a particle is subjected to an unsteady ambient flow, in terms of either time-dependent relative velocity or time-dependent temperature difference, the net heat transfer from the particle cannot be calculated based on the quasi-steady heat transfer correlation alone. Due to unsteady evolution of the thermal boundary layer, there is also a history contribution to heat transfer. The history contribution to heat transfer is expressed as a convolution integral of past evolution of temperature difference between the particle and the surrounding. While Basset history force and its finite Reynolds number extension have been well studied, similar understanding of unsteady heat transfer and thermal history kernel is lacking. Here, we use existing particle-resolved simulation results to develop a finite Peclet number thermal history kernel, which when used with the convolution integral is demonstrated to accurately predict unsteady heat transfer over a range of Peclet numbers and particle-to-fluid heat capacity ratio.

42 ENGINEERING↗
DOE OSTI2024

Nondestructive geochemical characterization of fossil hominin taphonomy and burial history

To date, only three Homo habilis specimens have been discovered that have associated craniodental and postcranial elements, providing a limited fossil record of the ontogeny and morphology of early members of the genus Homo. Recently, a nearly complete dentition, likely attributable to H. habilis, was discovered and excavated from early Pleistocene-age fluvial-lacustrine sediments of the upper Burgi Member of the Koobi Fora Formation at site F25787 in Area 13, near Ileret, Kenya. On the surface less than 15 m away, at site F25966, postcranial elements were found, which, if from the same individual as the nearby dentition, would represent the fourth associated craniodental and postcranial assemblage of this species. We developed a geochemical taphonomic history of these ca. 2 Ma hominin fossils using nondestructive X-ray based microanalytical tools (synchrotron and benchtop X-ray fluorescence chemical imaging and micro- and nano-computed tomography volumetric reconstruction), bulk analyses of sediments and paleosols at the excavation sites, and sedimentologic and stratigraphic observations. We integrate the chemical and physical taphonomic histories to test whether teeth (excavated in situ) and postcranial bones (eroded onto the outcrop surface) derive from a single individual. Minor differences in taphonomic history are attributable to the different biomineral properties of the dental and osseous components and to differences in physical damage during early post-mortem scavenging, dispersal, and burial in adjacent depositional settings. Microscale geochemical mapping enabled the temporal ordination of chemical and physical events in the specimens’ chemical taphonomic histories. Specifically, authigenic Fe- and K-bearing clays and Y, U, and Sr uptake occurred in post-burial fractures in bones and were also incorporated pervasively throughout dentin in teeth. Barite mineralization occurred along the latest fractures in both materials, and as a coating on tooth roots. The stratigraphic, taphonomic, and geochemical evidence supports the interpretation that the hominin fossils represent a single individual. Finally, successful application of these nondestructive sample characterization methods demonstrates capabilities for thorough interrogation of the taphonomic histories of other potential hominin fossil associations, enabling more robust and accurate palaeontologic constraints using those relationships.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Life history strategies of soil bacterial communities across global terrestrial biomes

The life history strategies of soil microbes determine their metabolic potential and their response to environmental changes. Yet these strategies remain poorly understood. Here we use shotgun metagenomes from terrestrial biomes to characterize overarching covariations of the genomic traits that capture dominant life history strategies in bacterial communities. The emerging patterns show a triangle of life history strategies shaped by two trait dimensions, supporting previous theoretical and isolate-based studies. The first dimension ranges from streamlined genomes with simple metabolisms to larger genomes and expanded metabolic capacities. As metabolic capacities expand, bacterial communities increasingly differentiate along a second dimension that reflects a trade-off between increasing capacities for environmental responsiveness or for nutrient recycling. Random forest analyses show that soil pH, C:N ratio and precipitation patterns together drive the dominant life history strategy of soil bacterial communities and their biogeographic distribution. Finally, our findings provide a trait-based framework to compare life history strategies of soil bacteria.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Machine-Learning-Based Multiscale Methods for 3D Modelling of Granular Materials by Incorporating History-Dependent State Variables

Over the past decades, the prevalence of machine learning (ML) methods has made the development of ML-based constitutive models for granular materials undoubtedly a popular subject. Numerous studies have been made to feature the loading path or history-dependent stress-strain response of granular media using neural networks. In this work, a novel finite element method (FEM)–ML multiscale approach was developed by incorporating internal variables to improve the simulation accuracy of 3D history-dependent granular materials for the first time. To this end, a surrogate constitutive model based on the single-step-based multi-layer perceptron (MLP) neural network was used to replace representative volume element (RVE) simulations conducted by the discrete element method (DEM) in the multiscale FEM–DEM approach. Although the prediction principle of the MLP aligns with the FEM algorithm, artificially added internal variables are required to differentiate the loading history. To address this issue, history variables associated with the Frobenius norm are proposed to be fed into the MLP coupled with the strain tensor to extract the history-dependent behaviour of granular assemblies. The developed FEM–ML approach was demonstrated in 3D conventional triaxial compression (CTC) simulations. Compared to the multiscale FEM–DEM approach, the proposed FEM–ML method exhibits a significantly improved computational efficiency.

granular materials↗