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Preservation of Previously Unsampled Primordial Isotopic Components in Ryugu and Bennu Samples

Ivuna-type (CI) carbonaceous chondrites are primitive meteorites whose relative elemental abundances closely match the solar photosphere 1 , making them critical benchmarks for the bulk chemical and isotopic composition of the planet-forming disk. Recent sample-return missions to Ryugu 2 and Bennu 3 have enabled direct laboratory analysis of these rubble-pile CI-like asteroids 4 , formed from the reaccumulated fragments of once-larger parent bodies. As such, they may retain a broader spectrum of primordial nucleosynthetic components than is preserved in known meteorites. Here, we report the nucleosynthetic compositions of silicon (μ 30 Si), magnesium (μ 26 Mg*), and iron (μ 54 Fe), three of the four most abundant planet-building elements, in samples from Ryugu and Bennu, along with the newly discovered Oued Chebeika 002 CI chondrite 5 . In contrast to the isotopic homogeneity of CI chondrites, Ryugu and Bennu preserve resolvable μ 26 Mg* and μ 30 Si heterogeneity, revealing μ 26 Mg*- and μ 30 Si-rich nucleosynthetic components not sampled in meteorites. These components may reflect the preservation of previously unsampled primordial isotopic signals, prior to thermal processing 6,7 and late infall of primordial molecular cloud material to the outer disk 8,9 . Additionally, Ryugu particle C0002 exhibits a μ 26 Mg*-poor and μ 54 Cr-rich signature, consistent with incorporation of presolar material from massive supernovae 10,11 . Ryugu and Bennu samples define one end of a μ 54 Fe–μ 30 Si array among carbonaceous asteroid materials 9 , suggesting that the isotopic compositions of these asteroidal materials reflect mixing between early disk isotopic components identified in this study and material derived from the outermost disk 9 . This observation demonstrates that materials with solar chemical abundances can nonetheless exhibit markedly distinct nucleosynthetic signatures. Thus, Ryugu and Bennu samples are critical records of nucleosynthetic diversity among carbonaceous asteroids and underscore the value of sample-return missions in accessing primitive isotopic signatures absent from meteorite collections.

Martin Bizzarro↗

DOE OSTI2015

Baseline scheme for polarization preservation and control in the MEIC ion complex

The scheme for preservation and control of the ion polarization in the Medium-energy Electron-Ion Collider (MEIC) has been under active development in recent years. The figure-8 configuration of the ion rings provides a unique capability to control the polarization of any ion species including deuterons by means of "weak" solenoids rotating the particle spins by small angles. Insertion of "weak" solenoids into the magnetic lattices of the booster and collider rings solves the problem of polarization preservation during acceleration of the ion beam. Universal 3D spin rotators designed on the basis of "weak" solenoids allow one to obtain any polarization orientation at an interaction point of MEIC. This paper presents the baseline scheme for polarization preservation and control in the MEIC ion complex.

43 PARTICLE ACCELERATORS↗

DOE OSTI2017

Reduced-Order Structure-Preserving Model for Parallel-Connected Three-Phase Grid-Tied Inverters: Preprint

Given that next-generation infrastructures will contain large numbers of grid-connected inverters and these interfaces will be satisfying a growing fraction of system load, it is imperative to analyze the impacts of power electronics on such systems. However, since each inverter model has a relatively large number of dynamic states, it would be impractical to execute complex system models where the full dynamics of each inverter are retained. To address this challenge, we derive a reduced-order structure-preserving model for parallel-connected grid-tied three-phase inverters. Here, each inverter in the system is assumed to have a full-bridge topology, LCL filter at the point of common coupling, and the control architecture for each inverter includes a current controller, a power controller, and a phase-locked loop for grid synchronization. We outline a structure-preserving reduced-order inverter model for the setting where the parallel inverters are each designed such that the filter components and controller gains scale linearly with the power rating. By structure preserving, we mean that the reduced-order three-phase inverter model is also composed of an LCL filter, a power controller, current controller, and PLL. That is, we show that the system of parallel inverters can be modeled exactly as one aggregated inverter unit and this equivalent model has the same number of dynamical states as an individual inverter in the paralleled system. Numerical simulations validate the reduced-order models.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE OSTI2022

Preservation of strain in iron nitride magnet

A permanent magnet may include a Fe 16 N 2 phase in a strained state. In some examples, strain may be preserved within the permanent magnet by a technique that includes etching an iron nitride-containing workpiece including Fe 16 N 2 to introduce texture, straining the workpiece, and annealing the workpiece. In some examples, strain may be preserved within the permanent magnet by a technique that includes applying at a first temperature a layer of material to an iron nitride-containing workpiece including Fe 16 N 2 , and bringing the layer of material and the iron nitride-containing workpiece to a second temperature, where the material has a different coefficient of thermal expansion than the iron nitride-containing workpiece. A permanent magnet including an Fe 16 N 2 phase with preserved strain also is disclosed.

Wang, Jian-Ping↗

DOE OSTI2023

Preservation of strain in iron nitride magnet

Wang, Jian-Ping↗

DOE OSTI2017

The Evolution of Community Engagement Through Ongoing Services Provided by the Fernald Preserve Visitors Center - 17402

The Fernald Preserve is located on the site of a former uranium-processing plant that underwent extensive environmental remediation followed by comprehensive ecological restoration. It is managed by the US Department of Energy Office of Legacy Management and is located approximately 29 kilometers (km) (18 miles) northwest of Cincinnati, Ohio. Remedial activities and subsequent ecological restoration have converted the site from an industrial production facility to an undeveloped park, encompassing a series of wetlands, prairies, and forested communities. Although the remediation of buildings and soil contamination was completed in 2006, site aquifer remediation is ongoing and remains a topic of interest to the community. Much of the site is open to the public, with approximately 11 km (7 miles) of year-round walking trails within the 425-hectare (1050-acre) site. The Fernald Preserve Visitors Center is open Wednesdays through Saturdays and site staff are available to accommodate program requests as needed. The Visitors Center was originally requested by stakeholders involved in developing recommendations for the site's final land use. Stakeholders requested a 'multi-use educational facility' that would recognize the site's history, serve as a source of site information, and recognize the contributions of energy workers during the Cold War. This building was converted from a warehouse built to support site cleanup and was ultimately awarded a Platinum rating by the U.S. Green Building Council. The Visitors Center was designed to accommodate site history exhibits, free meeting space for nonprofit groups, and public interpretive programs. It was opened to the public in 2008, and today's ongoing visitor services are continually adapted to meet the needs of current stakeholders. Over time, the interpretive services have evolved to include more diverse onsite cultural and natural history public programs, events, and activities. Today's community engagement efforts include public and private onsite programs and exhibits, public and private offsite programs and displays, meeting space, and regular open hours for the Visitors Center. This paper presents the various methods used to engage the greater Cincinnati community at the Fernald Preserve. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2019

Preserving the Mound Laboratory Legacy-The Mound Cold War Discovery Center - 19550

The Mound Cold War Discovery Center (MCWDC) opened at the former DOE Mound Laboratory in Miamisburg, Ohio, on April 23, 2018, approximately three years after the US Department of Energy (DOE) Office of Legacy Management, Dayton History, the Mound Science and EnergyMuseum Association (MSEMA), and the Mound Development Corporation signed the Mound Educational Center Memorandum of Agreement (MOA). This MOA designated each party's responsibilities for the facility and laid the groundwork for DOE to enter into a Cooperative Agreement with Dayton History to design, build, and perform initial operations of the educational center. Dayton History is a nonprofit organization that operates several historical facilities in Montgomery County, Ohio. The Mound Development Corporation is the nonprofit organization that operates the Mound Business Park, privately owned property previously associated with the former DOE Mound Laboratory. The US Atomic Energy Commission began operations at the Mound Laboratory in 1948 as an integrated research, development, and production facility that supported the nation's weapons and energy programs. In October 2015, DOE entered into a five-year Cooperative Agreement with Dayton History to preserve, protect, and make accessible legacy records and information about the history of the Mound site through the development of an educational center. Years One and Two were for design and construction, respectively. Years Three through Five were for operation of the new center. The new center, located in a building owned by the Mound Development Corporation, would carry on the mission started by the MSEMA, a nonprofit organization started by former Mound site employees more than 15 years ago after DOE mission work ended at the site. As part of the cooperative agreement, Dayton History is responsible for creating interactive displays and exhibits to draw, entertain, and educate the public on the Mound site's significant contributions to the protection of the nation; developing educational programs; and initiating marketing strategies for the long-term sustainability of the educational center. In 2016, parties to the MOA officially named the facility the Mound Cold War Discovery Center. The MCWDC was designed to preserve the history of the Mound site through effective, entertaining, and efficient communication of the history of the Mound Laboratory; the site's legacy to the US weapons production complex and space exploration program; and promote understanding of what has happened at the site since DOE mission work ended, including environmental cleanup under the Comprehensive Environmental Response, Compensation, and Liability Act and the regulator-approved end state of industrial/commercial land use with associated institutional controls. The cooperative agreement requires Dayton History to develop and implement marketing strategies to support the long-term sustainability of the MCWDC at the Mound site. Dayton History will submit a report after the first year of operation and every year thereafter during the period of the cooperative agreement. These reports will describe and status efforts to obtain sustainability and offer for consideration any operational changes, corrections, or suggestions that may improve the potential for sustainability. Prior to the end of the cooperative agreement, a sustainability assessment decision will be made by DOE to determine whether the MCWDC has enough community interest to financially sustain itself at the Mound site. The status of the MCWDC Legacy Fund established by Dayton History will be considered in DoE's assessment determination. If DOE determines that the MCWDC is not sustainable at the Mound site, the exhibits will be relocated to Carillon Historical Park in Dayton, with the five key exhibits that were predetermined in the MOA to be placed on permanent display, thereby maintaining the legacy of the Mound site. Dayton History is required to submit a final closeout report at the end of Year Five of the cooperative agreement. The report will describe all activities completed under the agreement, provide an assessment of how project goals were achieved or not achieved, and describe how the legacy of the site will be preserved. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2019

Successful Implementation of a Natural Resource Restoration Plan at the Fernald Preserve - 19568

The Fernald Preserve, Ohio, Site is a former uranium-processing plant that underwent extensive remediation pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). It is situated on a 425-hectare (ha) (1050-acre) tract of land, approximately 29 kilometers (km) (18 miles) northwest of Cincinnati, Ohio. The US Department of Energy (DOE) Office of Legacy Management is responsible for management of the site. Site remediation and subsequent ecological restoration have converted the site from an industrial production facility to an undeveloped park, encompassing a series of wetlands, prairies, and forested communities. The remediation of buildings and contaminated soil was completed in 2006, but aquifer remediation is ongoing. Portions of the site are open to the public, including approximately 11 km (7 miles) of walking trails that are open year-round and a Fernald Preserve Visitors Center open four days a week. Stakeholders were instrumental in providing recommendations for final land use of the site as an undeveloped park with an emphasis on wildlife. Final land use decisions were also instrumental in the resolution of a CERCLA natural resource damage claim. The State of Ohio sued DOE in 1986 for damages to state natural resources under Section 107 of CERCLA. The suit was stayed until completion of all Records of Decision (RODs) for the site. The last ROD was signed in 1996. DOE, which was both a Natural Resource Trustee (NRT) and a potentially responsible party (PRP) under CERCLA, initiated consultation with other site NRTs in 1993. A Trustee Council was formed that included DOE, Ohio Environmental Protection Agency (representing the State of Ohio), and the US Fish and Wildlife Service (representing the US Department of the Interior). The NRTs agreed collectively to conduct sitewide ecological restoration, consistent with the stakeholder vision of final land use. A conceptual restoration plan was drafted in 1998. This Natural Resource Restoration Plan (NRRP) developed goals for site restoration, as well as provisions for monitoring and maintenance of restored areas. The NRTs signed a Memorandum of Understanding in 2001, and DOE integrated ecological restoration design and construction into remediation and closure activities for the site. The NRT relationship became contentious in the following years as a result of a disagreement over monitoring commitments and compensation for groundwater injury. Final settlement was reached in 2008. As part of the settlement, DOE paid $13.75 million into the NRT fund as compensation for natural resource damages. In addition, the NRRP was finalized, and long-term commitments for monitoring and maintenance of ecologically restored areas were put in place. An Environmental Covenant was established and recorded with Hamilton and Butler Counties that ensures site activity and use limitations remain in place. The NRTs used a portion of the settlement funds to initiate the Paddys Run Conservation Project. This effort is a means to secure development rights and conservation easements within the Paddys Run watershed. Paddys Run is a third-order stream located on the western side of the Fernald Preserve. The NRTs partnered with Three Valley Conservation Trust to obtain assistance with land acquisition and conservation easement management, and since the program's inception in the Fall of 2012, more than 1820 ha (4500 acres) have been permanently protected via easement or purchase. Future decisions by the NRTs regarding monitoring and maintenance of restored areas will be negotiated in 2020. The site Restored Area Maintenance Plan (RAMP) was developed in 2010. The RAMP is a requirement within the NRRP and is scheduled for review following 10 years of implementation. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2025

Recommendations for Best Practices for Data Preservation and Open Science in HEP

These recommendations are the result of reflections by scientists and experts who are, or have been, involved in the preservation of high-energy physics data. The work has been done under the umbrella of the Data Lifecycle panel of the International Committee of Future Accelerators (ICFA), drawing on the expertise of a wide range of stakeholders. A key indicator of success in the data preservation efforts is the long-term usability of the data. Experience shows that achieving this requires providing a rich set of information in various forms, which can only be effectively collected and preserved during the period of active data use. The recommendations are intended to be actionable by the indicated actors and specific to the particle physics domain. They cover a wide range of actions, many of which are interdependent. These dependencies are indicated within the recommendations and can be used as a road map to guide implementation efforts. These recommendations are best accessed and viewed through the web application, see https://icfa-data-best-practices.app.cern.ch/

Campana, Simone [CERN]↗

DOE OSTI2019

A Positive Asymptotic-Preserving Scheme for Linear Kinetic Transport Equations

We present a positive- and asymptotic-preserving numerical scheme for solving linear kinetic transport equations that relax to a diffusive equation in the limit of infinite scattering. The proposed scheme is developed using a standard spectral angular discretization and a classical micro-macro decomposition. The three main ingredients are a semi-implicit temporal discretization, a dedicated finite difference spatial discretization, and realizability limiters in the angular discretization. Under mild assumptions, the scheme becomes a consistent numerical discretization for the limiting diffusion equation when the scattering cross-section tends to infinity. The scheme also preserves positivity of the particle concentration on the space-time mesh and therefore fixes a common defect of spectral angular discretizations. The scheme is tested on the well-known line source benchmark problem with the usual uniform material medium as well as a medium composed of different materials that are arranged in a checkerboard pattern. We also tested the scheme on a Riemann problem with a nonuniform material medium. The observed order of space-time accuracy of the proposed scheme is reported.

nite difference methods↗

DOE OSTI2025

Best Practices for Nuclear Experiment Data Preservation at Idaho National Laboratory: A Guide for Researchers and Reactor Operators

Preserving experimental data is essential for supporting advancements in nuclear science and ensuring the longevity of Idaho National Laboratory's contributions to reactor technology and safety. This report provides a comprehensive guide to best practices for experimental data management and preservation, focusing on standardized data formats, redundancy in storage, metadata documentation, and alignment with international standards. By following these recommendations, experimentalists and reactor operators can enhance the accessibility, reproducibility, and utility of critical datasets for regulatory review, validation computational methods, and future research.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DOE OSTI2015

Evidence from the ancient world on long-term preservation of artifacts - 15442

As a cradle and crossroads of civilizations, a bridge between the ancient political and cultural centers of Mesopotamia and Egypt, and home to three major religions, the land of Israel is rich with archaeological artifacts. Dating back thousands of years, many such artifacts have been preserved in remarkable condition - enduring the tumultuous test of time, environment, and regional turmoil. The study of these artifacts can undoubtedly serve as an analogue for a modern, permanent marker system for a geologic nuclear waste repository, shedding light on how a marker can endure man-made and natural disasters over thousands of years. Indeed, these artifacts, and our ability to decipher their various messages, not only provide us with a rich knowledge of our ancestors from the past, but they likewise provide insight into the techniques and conditions needed for long-term preservation and endurance of man-made items over time. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2019

Strong Stability Preserving Integrating Factor Two-Step Runge-Kutta Methods

In this report, problems with components that feature significantly different time scales, where the stiff time-step restriction comes from a linear component, implicit-explicit (IMEX) methods alleviate this restriction if the concern is linear stability. However, when nonlinear non-inner-product stability properties are of interest, such as in the evolution of hyperbolic partial differential equations with shocks or sharp gradients, linear inner-product stability is no longer sufficient for convergence, and so strong stability preserving (SSP) methods are often needed. Where the SSP property is needed, IMEX SSP Runge-Kutta (SSP-IMEX) methods have very restrictive time-steps. An alternative to SSP-IMEX schemes is to adopt an integrating factor approach to handle the linear component exactly and step the transformed problem forward using some time-evolution method. The strong stability properties of integrating factor Runge-Kutta methods were established in Isherwood et al. (SIAM J Numer Anal 56(6):3276–3307, 2018), where it was shown that it is possible to define explicit integrating factor Runge-Kutta methods that preserve strong stability properties satisfied by each of the two components when coupled with forward Euler time-stepping. It was proved that the solution will be SSP if the transformed problem is stepped forward with an explicit SSP Runge-Kutta method that has non-decreasing abscissas. However, explicit SSP Runge-Kutta methods have an order barrier of p=4, and sometimes higher order is desired. In this work we consider explicit SSP two-step Runge-Kutta integrating factor methods to raise the order. We show that strong stability is ensured if the two-step Runge-Kutta method used to evolve the transformed problem is SSP and has non-decreasing abscissas. We find such methods up to eighth order and present their SSP coefficients. Adding a step allows us to break the fourth order barrier on explicit SSP Runge-Kutta methods; furthermore, our explicit SSP two-step Runge-Kutta methods with non-decreasing abscissas typically have larger SSP coefficients than the corresponding one-step methods. A selection of our methods are tested for convergence and demonstrate the design order. We also show, for selected methods, that the SSP time-step predicted by the theory is a lower bound of the allowable time-step for linear and nonlinear problems that satisfy the total variation diminishing (TVD) condition. We compare some of the non-decreasing abscissa SSP two-step Runge-Kutta methods to previously found methods that do not satisfy this criterion on linear and nonlinear TVD test cases to show that this non-decreasing abscissa condition is indeed necessary in practice as well as theory. We also compare these results to our SSP integrating factor Runge-Kutta methods designed in Isherwood et al. (2018).

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2026

A sweeping positivity-preserving high-order finite difference WENO scheme for Euler equations

We develop a simple, high-order, conservative and robust positivity-preserving sweeping procedure for the density and the nonlinear pressure function in the compressible Euler equations. Using the scaling limiter in Zhang and Shu (J Comput Phys 229:3091–3120, 2010), we obtain a non-trivial extension of the scalar sweeping technique in Liu et al. (J Sci Comput 73:1028–1071, 2017) for the positivity of pressure. The sweeping procedure developed in this paper is a post-processing technique, which can be applied to any concave functions of the conserved variables in hyperbolic conservation law systems. Thus, it has applications beyond the Euler equations. This procedure preserves positivity and conservation of physical quantities without destroying the accuracy of the underlying scheme. The algorithm works for general schemes including finite difference, finite volume and discontinuous Galerkin methods; however, in this paper we focus on finite difference weighted essentially non-oscillatory (WENO) methods. As a result, we provide numerical tests of the fifth-order finite difference WENO scheme to demonstrate the accuracy and robustness of the technique.

Compressible Euler equations↗

DOE OSTI2022

Embedded pairs for optimal explicit strong stability preserving Runge–Kutta methods

We construct a family of embedded pairs for optimal explicit strong stability preserving Runge–Kutta methods of order 2 ≤ p ≤ 4 to be used to obtain numerical solution of spatially discretized hyperbolic PDEs. In this construction, the goals include non-defective property, large stability region, and small error values as defined in Dekker and Verwer (1984) and Kennedy et al. (2000). The new family of embedded pairs offer the ability for strong stability preserving (SSP) methods to adapt by varying the step-size. Through several numerical experiments, we assess the overall effectiveness in terms of work versus precision while also taking into consideration accuracy and stability.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2022

Physics-informed regularization and structure preservation for learning stable reduced models from data with operator inference

Operator inference learns low-dimensional dynamical-system models with polynomial nonlinear terms from trajectories of high-dimensional physical systems (non-intrusive model reduction). Here, this work focuses on the large class of physical systems that can be well described by models with quadratic and cubic nonlinear terms and proposes a regularizer for operator inference that induces a stability bias onto learned models. The proposed regularizer is physics informed in the sense that it penalizes higher-order terms with large norms and so explicitly leverages the polynomial model form that is given by the underlying physics. This means that the proposed approach judiciously learns from data and physical insights combined, rather than from either data or physics alone. Additionally, a formulation of operator inference is proposed that enforces model constraints for preserving structure such as symmetry and definiteness in linear terms. Numerical results demonstrate that models learned with operator inference and the proposed regularizer and structure preservation are accurate and stable even in cases where using no regularization and Tikhonov regularization leads to models that are unstable.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2021

Slow manifolds of classical Pauli particle enable structure-preserving geometric algorithms for guiding center dynamics

Since variational symplectic integrators for the guiding center was proposed, structure-preserving geometric algorithms have become an active research field in plasma physics. We found that the slow manifolds of the classical Pauli particle enable a family of structure-preserving geometric algorithms for guiding center dynamics with long-term stability and accuracy. This discovery overcomes the difficulty associated with the unstable parasitic modes for variational symplectic integrators when applied to the degenerate guiding center Lagrangian. It is a pleasant surprise that Pauli's Hamiltonian for electrons, which predated the Dirac equation and marks the beginning of particle physics, reappears in classical physics as an effective algorithm for solving an important plasma physics problem. This technique is applicable to other degenerate Lagrangians reduced from regular Lagrangians.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2018

Local bounds preserving stabilization for continuous Galerkin discretization of hyperbolic systems

The objective of this paper is to present a local bounds preserving stabilized finite element scheme for hyperbolic systems on unstructured meshes based on continuous Galerkin (CG) discretization in space. A CG semi-discrete scheme with low order artificial dissipation that satisfies the local extremum diminishing (LED) condition for systems is used to discretize a system of conservation equations in space. The low order artificial diffusion is based on approximate Riemann solvers for hyperbolic conservation laws. In this case we consider both Rusanov and Roe artificial diffusion operators. In the Rusanov case, two designs are considered, a nodal based diffusion operator and a local projection stabilization operator. The result is a discretization that is LED and has first order convergence behavior. To achieve high resolution, limited antidiffusion is added back to the semi-discrete form where the limiter is constructed from a linearity preserving local projection stabilization operator. The procedure follows the algebraic flux correction procedure usually used in flux corrected transport algorithms. To further deal with phase errors (or terracing) common in FCT type methods, high order background dissipation is added to the antidiffusive correction. The resulting stabilized semi-discrete scheme can be discretized in time using a wide variety of time integrators. Numerical examples involving nonlinear scalar Burgers equation, and several shock hydrodynamics simulations for the Euler system are considered to demonstrate the performance of the method. In conclusion, for time discretization, Crank–Nicolson scheme and backward Euler scheme are utilized.

97 MATHEMATICS AND COMPUTING↗