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All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Trapped-ion quantum simulation of electron transfer models with tunable dissipation

Electron transfer is at the heart of many fundamental physical, chemical, and biochemical processes essential for life. The exact simulation of these reactions is often hindered by the large number of degrees of freedom and by the essential role of quantum effects. Here, we experimentally simulate a paradigmatic model of molecular electron transfer using a multispecies trapped-ion crystal, where the donor-acceptor gap, the electronic and vibronic couplings, and the bath relaxation dynamics can all be controlled independently. By manipulating both the ground-state and optical qubits, we observe the real-time dynamics of the spin excitation, measuring the transfer rate in several regimes of adiabaticity and relaxation dynamics. Our results provide a testing ground for increasingly rich models of molecular excitation transfer processes that are relevant for molecular electronics and light-harvesting systems.

Science & Technology - Other Topics↗
DOE OSTI2026

Optimal Transfer Operators in Algebraic Two-Level Methods for Nonsymmetric and Indefinite Problems

Consider an algebraic two-level method applied to the 𝑛-dimensional linear system 𝐴⁢𝒙 = 𝒃 using fine-space preconditioner (i.e., “relaxation” or “smoother”) 𝑀, with 𝑀 ≈ 𝐴, restriction and interpolation 𝑅 and 𝑃, and algebraic coarse-space operator 𝐴 𝑐 : = 𝑅 ∗ ⁢𝐴⁢𝑃. Then, what are the best possible transfer operators 𝑅 and 𝑃 of a given dimension 𝑛 𝑐 < 𝑛? Brannick et al. [12] showed that when 𝐴 and 𝑀 are Hermitian positive definite (HPD), the optimal interpolation is such that its range contains the 𝑛 𝑐 smallest generalized eigenvectors of the matrix pencil (𝐴, 𝑀). Recently, in Ali et al. [5] we generalized this framework to the non-HPD setting, by considering both right (interpolation) and left (restriction) generalized eigenvectors of (𝐴, 𝑀) and defining corresponding nonsymmetric transfer operators {𝑅#, 𝑃#}. Tight convergence bounds for {𝑅#, 𝑃#} are derived in spectral radius, as well as a proof of pseudo-optimality. Note, {𝑅#, 𝑃#} are typically complex valued, which is not practical for real-valued problems. Here, in this work, we build on [5], first characterizing all inner products in which the coarse-space correction defined by {𝑅#, 𝑃#} is orthogonal. We then develop tight two-level convergence bounds in these norms, and prove that the underlying transfer operators {𝑅#, 𝑃#} are genuinely optimal. As a special case, our theory both recovers and extends the HPD results from [12]. Finally, we show how to construct optimal, real-valued transfer operators in the case of that 𝐴 and 𝑀 are real valued, but are not HPD. Numerical examples arising from a discretized advection-reaction equation, wave-equation, and Stokes equations are used to verify and illustrate the theory.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2016

Synthesis of new transuranium isotopes in multinucleon transfer reactions using a velocity filter

Recently, we reported the observation of several new isotopes with proton numbers Z ≥ 92 in low-energy collisions of 48 Ca + 248 Cm . The peculiarity is that the nuclei were produced in multinucleon transfer reactions, a method which is presently discussed as a possible new way to enter so far unknown regions in the upper part of the Chart of Nuclides. For separation of the transfer products we used a velocity filter, the Separator for Heavy Ion Reaction Products SHIP at GSI. The resulting strong background suppression allowed us to detect nuclei with cross-sections down to the sub-nanobarn scale. Beside the new isotopes we identified about 100 further target-like transfer products and determined their cross-sections. In conclusion, the results together with previous measurements strongly indicate that multinucleon transfer reactions are a viable pathway to the production of new transuranium isotopes.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Shell-model calculations for two-neutron transfer near the $N=20$ island of inversion

We describe connections between shell-model calculation results and predictions for two-nucleon transfer reactions. Measurements of the 30 Mg(t,p) 32 Mg reaction were used to identify a low-lying shape-coexisting 0 + state in 32 Mg. Interpretations of those early, limited data were based on simple empirical models. The cross sections for two-nucleon transfer are, however, extremely sensitive to the details of the nuclear-structure. Motivated by the possibility of new high-resolution two-nucleon transfer measurements around the N = 20 Island of Inversion, we have performed shell-model calculations wave functions for states in the nuclei 30,32 Mg using the SDPF-M and SDPF-MU interactions, and from those calculations obtain the two-nucleon transfer amplitudes that we use to predict cross sections for the 28,30 Mg(t,p) 30,32 Mg reactions. The combined results show how the nuclear structure properties influence experimental observables for the (t,p) reaction. We compare our results with the existing data.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

The eRHIC spin rotator and the beam optics of the 400 MeV transfer line to RCS

The 400 MeV LINAC 1 of the proposed eRHIC collider 1 is the first acceleration stage of the 18 GeV electron accelerator. The second acceleration stage of the electron accelerator is the Rapid Cycling Synchrotron (RCS), which can increase the energy of the electron bunches to 18 GeV and subsequently extract transfer and inject the 18 GeV electron bunches into the 18 GeV electron Storage Ring (SR) to collide with the hadron bunches of the existing (Relativistic Heavy Ion Collider (RHIC)) accelerator. This paper describes the beam optics of the transfer line between the 400 MeV LINAC and the RCS accelerator (LtRCS). The function of the LtRCS line is twofold, first to transfer the electron beam from the exit of the 400 MeV LINAC to the injection point of the RCS 1 and second to rotate the stable spin direction of the polarized electrons from the longitudinal direction to the vertical. A detailed description of the constraints to be satisfied by the LtRCS transfer line will be given. Finally, a section will also be devoted to discuss the spin rotator 2 .

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

Electrochemical Characterization of Biomolecular Electron Transfer at Conductive Polymer Interfaces

Bio-electrochemical systems (BESs) are promising for renewable energy generation but remain hindered by inefficient electron transfer at electrode surfaces. As the toolbox of bio-anode materials increases, rigorous electrochemical characterization of emerging materials is needed. Here, we holistically characterize the electrochemical interaction of flavin mononucleotide (FMN), an electron shuttle in biological systems and a cofactor for oxidoreductase enzymes, with the bio-inspired mixed conducting polymer poly{3-[6'-(N-methylimidazolium)hexyl]thiophene} (P3HT-Im + ). The behavior of this polymer is compared to the equivalent polymer without the histidine-like imidazolium. We find improved conductivity and charge storage in imidazolium-containing polymers beyond what is explained by differences in the electroactive area. The P3HT-Im + further shows internal charge storage but with negligible faradaic contribution, indicating that charge storage capacity may translate to improved biocatalysis non-intuitive ways. Finally, one-electron transfer is observed between FMN and glassy carbon, while a bio-similar two-electron transfer is observed for the P3HT-Im + . To our knowledge, this is the first example of a concerted two-electron transfer between FMN and an electrode interface, which we attribute to the bio-inspired, histidine-like imidazolium functional groups in the polymer. These studies demonstrate the importance of bio-relevant materials characterization when such materials are deployed in BESs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Understanding the Role of Complexation in the Charge-Transfer Kinetics of the Cu 2+ + e ↔ Cu 1+ Redox Reaction in Ethaline Deep Eutectic Solvent

Deep eutectic solvent (DES) based electrolytes are gaining attention for electrochemical applications. As such, knowledge of the charge transfer kinetics in DES and its dependence on electrolyte composition and temperature is important. Using Cu 2+ + e ↔ Cu 1+ as a model system, we demonstrate that metal redox reactions in chloride-containing DES media suffer from sluggish charge transfer kinetics. The exchange current density, i 0 , displayed a peculiar inverse relationship with the bulk chloride concentration, [Cl – ] b . The i 0 decreased from 7.9 to 3.0 mA/cm 2 when [Cl – ] b increased from 2.8 to 4.6 M at 30°C. Such dependence is shown to originate from Cl – complexation with reactant and product species. Furthermore, i 0 increased with an increase in Cu n + bulk concentration in the 50–200 mM range. Also, increase in temperature elevated i 0 . The charge transfer coefficient α c , however, remained constant (~0.5) and was unaffected by Cu n + or Cl – concentrations or by temperature. To explain how charge transfer kinetics depend on the various system parameters, a model incorporating complexation phenomena was developed and its predictions were compared to experiments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

NUMA-Aware Thread Scheduling for Big Data Transfers over Terabits Network Infrastructure

The evergrowing trend of big data has led scientists to share and transfer the simulation and analytical data across the geodistributed research and computing facilities. However, the existing data transfer frameworks used for data sharing lack the capability to adopt the attributes of the underlying parallel file systems (PFS). LADS (Layout-Aware Data Scheduling) is an end-to-end data transfer tool optimized for terabit network using a layout-aware data scheduling via PFS. However, it does not consider the NUMA (Nonuniform Memory Access) architecture. In this paper, we propose a NUMA-aware thread and resource scheduling for optimized data transfer in terabit network. First, we propose distributed RMA buffers to reduce memory controller contention in CPU sockets and then schedule the threads based on CPU socket and NUMA nodes inside CPU socket to reduce memory access latency. We design and implement the proposed resource and thread scheduling in the existing LADS framework. Experimental results showed from 21.7% to 44% improvement with memory-level optimizations in the LADS framework as compared to the baseline without any optimization.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2022

A Right Transfer Access Control Model of Internet of Things Based on Smart Contract

Sensor nodes play a crucial role in the promotion of development of Internet of Things (IoT). Through this transaction, RO defines access control policies in script form based on ABAC's access control model to grant access right. The identity of all users in the model is identified by address. This paper builds a more flexible right transfer access control model by means of combining the Attribute-Based Access Control model (ABAC) and blockchain technology. Owing to the characteristics of ABAC’s attributes and right association, the massive problems of some sensor nodes can be solved. At the same time, for the sake of addressing the dynamic problems such as node access and right transfer, right transfer contract (TS) and access control contract (CS) are employed on the chain to ensure efficient and safe transmission of rights. To solve on-chain storage problems and ensure transparency of the operation, the idea of Rollup in Ethereum expansion is used to upload the final state of protocol policy and right exchange to the chain. Any user can know the policy and current right transfer status at any time. Finally, comparative and security analysis show that the model presented here can solve IoT devices’ massive and dynamic problems more effectively and it is more secure than the traditional models.

Wang, Jiuru↗
DOE OSTI2018

Improvement of the Simulation of Cloud Longwave Scattering in Broadband Radiative Transfer Models

Abstract Cloud longwave scattering is generally neglected in general circulation models (GCMs), but it plays a significant and highly uncertain role in the atmospheric energy budget as demonstrated in recent studies. To reduce the errors caused by neglecting cloud longwave scattering, two new radiance adjustment methods are developed that retain the computational efficiency of broadband radiative transfer simulations. In particular, two existing scaling methods and the two new adjustment methods are implemented in the Rapid Radiative Transfer Model (RRTM). The results are then compared with those based on the Discrete Ordinate Radiative Transfer model (DISORT) that explicitly accounts for multiple scattering by clouds. The two scaling methods are shown to improve the accuracy of radiative transfer simulations for optically thin clouds but not effectively for optically thick clouds. However, the adjustment methods reduce computational errors over a wide range, from optically thin to thick clouds. With the adjustment methods, the errors resulting from neglecting cloud longwave scattering are reduced to less than 2 W m−2 for the upward irradiance at the top of the atmosphere and less than 0.5 W m−2 for the surface downward irradiance. The adjustment schemes prove to be more accurate and efficient than a four-stream approximation that explicitly accounts for multiple scattering. The neglect of cloud longwave scattering results in an underestimate of the surface downward irradiance (cooling effect), but the errors are almost eliminated by the adjustment methods (warming effect).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Progressive transfer learning for low-frequency data prediction in full waveform inversion

To effectively overcome the cycle-skipping issue in full waveform inversion (FWI), we developed a deep neural network (DNN) approach to predict the absent low-frequency components by exploiting the hidden physical relation connecting the low- and the high-frequency data. To efficiently solve this challenging nonlinear regression problem, two novel strategies were proposed to design the DNN architecture and to optimize the learning process: (1) dual data feed structure; (2) progressive transfer learning. With the dual data feed structure, not only the high-frequency data, but also the corresponding beat tone data are fed into the DNN to relieve the burden of feature extraction. The second strategy, progressive transfer learning, enables us to train the DNN using a single evolving training dataset. Within the framework of the progressive transfer learning, the training dataset continuously evolves in an iterative manner by gradually retrieving the subsurface information through the physics-based inversion module, progressively enhancing the prediction accuracy of the DNN and propelling the inversion process out of the local minima. Here, the synthetic numerical experiments suggest that, without any a priori geological information, the low-frequency data predicted by the progressive transfer learning are sufficiently accurate for an FWI engine to produce reliable subsurface velocity models free of cycle-skipping artifacts.

02 PETROLEUM↗
DOE OSTI2015

Numerical Analysis of Coolant Flow and Heat Transfer in ITER Diagnostic First Wall

We performed numerical simulations of the ITER Diagnostic First Wall (DFW) using ANSYS workbench. During operation DFW will include solid main body as well as liquid coolant. Thus thermal and hydraulic analysis of the DFW was performed using conjugated heat transfer approach, in which heat transfer was resolved in both solid and liquid parts, and simultaneously fluid dynamics analysis was performed only in the liquid part. This approach includes interface between solid and liquid part of the systemAnalysis was performed using ANSYS CFX software. CFX software allows solution of heat transfer equations in solid and liquid part, and solution of the flow equations in the liquid part. Coolant flow in the DFW was assumed turbulent and was resolved using Reynolds averaged Navier-Stokes equations with Shear Stress Transport turbulence model. Meshing was performed using CFX method available within ANSYS. The data cloud for thermal loading consisting of volumetric heating and surface heating was imported into CFX Volumetric heating source was generated using Attila software. Surface heating was obtained using radiation heat transfer analysis. Our results allowed us to identify areas of excessive heating. Proposals for cooling channel relocation were made. Additional suggestions were made to improve hydraulic performance of the cooling system.

42 ENGINEERING↗
DOE OSTI2024

Optimizing spectral phase transfer in four-wave mixing with gas-filled capillaries

Four-wave mixing (FWM) in gas-filled hollow-core capillaries, a nonlinear optical process that mixes signal and pump photon frequencies to generate idler frequency photons, offers a method for precise spectral phase transfer from signal to idler at ultrashort timescales and extreme powers. However, this regime is challenged by competing linear and nonlinear dynamics, leading to significant trade-offs between spectral phase transfer and conversion efficiency. Our computational investigation focuses on the upconversion of femtosecond pulses from the infrared (IR) to the ultraviolet (UV), a range notoriously difficult to manipulate. We explore an intermediate energy regime that strikes an optimal balance between FWM-mediated phase-transfer fidelity and nonlinear conversion efficiency. By adjusting the energy ratios and spectral phase profiles of the input signal, we achieve conversion efficiencies of approximately 5-15% while maintaining an effective quasi-linear spectral phase transfer. These findings will contribute to establishing first-principles and scaling laws essential for applications such as high-precision imaging, spectroscopy, quantum transduction, and distributed entangled interconnects, facilitating advanced control of ultrafast photonic and electronic wavepackets in quantum materials with unprecedented spatial and temporal precision.

Zhang, Hao↗
DOE OSTI2023

Ceramide-1-phosphate transfer protein enhances lipid transport by disrupting hydrophobic lipid–membrane contacts

Cellular distributions of the sphingolipid ceramide-1-phosphate (C1P) impact essential biological processes. C1P levels are spatiotemporally regulated by ceramide-1-phosphate transfer protein (CPTP), which efficiently shuttles C1P between organelle membranes. Yet, how CPTP rapidly extracts and inserts C1P into a membrane remains unknown. Here, we devise a multiscale simulation approach to elucidate biophysical details of CPTP-mediated C1P transport. We find that CPTP binds a membrane poised to extract and insert C1P and that membrane binding promotes conformational changes in CPTP that facilitate C1P uptake and release. By significantly disrupting a lipid’s local hydrophobic environment in the membrane, CPTP lowers the activation free energy barrier for passive C1P desorption and enhances C1P extraction from the membrane. Upon uptake of C1P, further conformational changes may aid membrane unbinding in a manner reminiscent of the electrostatic switching mechanism used by other lipid transfer proteins. Insertion of C1P into an acceptor membrane, eased by a decrease in membrane order by CPTP, restarts the transfer cycle. Most notably, we provide molecular evidence for CPTP’s ability to catalyze C1P extraction by breaking hydrophobic C1P–membrane contacts with compensatory hydrophobic lipid–protein contacts. Our work, thus, provides biophysical insights into how CPTP efficiently traffics C1P between membranes to maintain sphingolipid homeostasis and, additionally, presents a simulation method aptly suited for uncovering the catalytic mechanisms of other lipid transfer proteins.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2014

RELAP5-3D Modeling of Heat Transfer Components (Intermediate Heat Exchanger and Helical-Coil Steam Generator) for NGNP Application

The Next Generation Nuclear Plant project is aimed at the research and development of a helium-cooled high-temperature gas reactor that could generate both electricity and process heat for the production of hydrogen. The heat from the high-temperature primary loop must be transferred via an intermediate heat exchanger to a secondary loop. Using RELAP5-3D, a model was developed for two of the heat exchanger options a printed-circuit heat exchanger and a helical-coil steam generator. The RELAP5-3D models were used to simulate an exponential decrease in pressure over a 20 second period. The results of this loss of coolant analysis indicate that heat is initially transferred from the primary loop to the secondary loop, but after the decrease in pressure in the primary loop the heat is transferred from the secondary loop to the primary loop. A high-temperature gas reactor model should be developed and connected to the heat transfer component to simulate other transients.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2024

Transfer learning for metamaterial design and simulation

Abstract We demonstrate transfer learning as a tool to improve the efficacy of training deep learning models based on residual neural networks (ResNets). Specifically, we examine its use for study of multi-scale electrically large metasurface arrays under open boundary conditions in electromagnetic metamaterials. Our aim is to assess the efficiency of transfer learning across a range of problem domains that vary in their resemblance to the original base problem for which the ResNet model was initially trained. We use a quasi-analytical discrete dipole approximation (DDA) method to simulate electrically large metasurface arrays to obtain ground truth data for training and testing of our deep neural network. Our approach can save significant time for examining novel metasurface designs by harnessing the power of transfer learning, as it effectively mitigates the pervasive data bottleneck issue commonly encountered in deep learning. We demonstrate that for the best case when the transfer task is sufficiently similar to the target task, a new task can be effectively trained using only a few data points yet still achieve a test mean absolute relative error of 3 % with a pre-trained neural network, realizing data reduction by a factor of 1000.

Peng, Rixi↗
DOE OSTI2024

A NUMERICAL STUDY OF HEAT TRANSFER IN THE FUEL CELL OF A SOLID OXIDE FUEL CELL-COMBUSTOR

A Solid Oxide Fuel Cell-Combustor (SOFC-C) concept was proposed to address many challenges a traditional fuel cell-gas turbine hybrid system (FC-GT) will have in aerospace applications. By taking advantage of the temperature rise during compression and the combustion of anode off-gas, the SOFC-C eliminates the recuperating heat exchanger usually required for cathode flows, greatly reducing the size and weight (thermal mass) of the system. The fuel cell is one of the key parts of the SOFC-C, so it is desired to understand the heat transfer in the fuel cell. In present work, a computational fluid dynamic (CFD) model was developed to reveal the gas flow and heat transfer in the fuel cell of the SOFC-C. The model includes not only convection heat transfer, but also includes the radiation heat transfer. The modeling results help to optimize the SOFC-C design.

Zhang, Mingkan↗
DOE OSTI2015

Targeted Technology Transfer to US Independents

The Petroleum Technology Transfer Council (PTTC) is a unique not-for-profit network that focuses on transferring Exploration and Production (E&P) technology to the domestic oil and natural gas producing industry. PTTC connects producers, technology providers and innovators, academia, research and development (R&D) consortiums and governments. Local affordable workshops delivered by Regional Lead Organizations (RLOs), which are typically a university or geological survey, are a primary tool. PTTC also maintains a website network, issues a national newsletter, provides a column in a major trade publication, and exhibits at major industry events. It also encourages industry to ask technology-related questions, striving to find relevant answers that will save questioners significant time. Working since late 1993, the PTTC network has a proven track record of providing industry with technology insights they can apply. Volunteers at the regional and national level provide key guidance regarding where to focus technical effort and help connect PTTC with industry. At historical funding levels, PTTC had been able to hold well more than 100 workshops per year, drawing 6,000+ attendees. As funding decreased in the early 2000s, the level of activity decreased and PTTC sought a merger with the American Association of Petroleum Geologists (AAPG), becoming an AAPG-managed organization at the start of FY08. This relationship with AAPG was terminated by mutual consent in May 2011 and PTTC once again operates independently. Chris Hall, California continued to serve as Chairman of the Board of Directors until December 2013. At the time PTTC reorganized into a RLO led organization with Mary Carr and Jeremy Viscomi as co-Executive Directors. Jerry Anderson became the Chairman of the PTTC Board of Directors and Chris Hall continues to serve on the Board. Workshop activity stabilized at 55-65 workshops per year averaging 3,100 attendees. FY14 represented the fifth year in a multi-year contract with the Department of Energy (DOE) for providing technology transfer services. This report summarizes activity and results during for five years, FY10 through FY14. In FY12 changes occurred in responsibilities of consultants serving HQ, because funding was reduced below the threshold level of $500,000 audits were no longer required and consultant time was reduced on the primary contract. Contracts for Permian Carbon Capture Utilization and Storage (CCUS) training, and providing tech transfer services to the Research Partnership to Secure Energy for America (RPSEA) provided work that enabled HQ to retain services of regular consultants. Both CCUS and RPSEA were five year contracts with PTTC, and providing services for these DOE funded contracts provided synergy for PTTC and the oil and gas industry. With further decreases in DOE funding the regions conducted workshops with no PTTC funding starting in June FY11. Since 2011 the number of workshops has declined from 79 in FY10 and FY11 to 49 in FY12, and risen to 54 in FY13 and 63 in FY14. The attendee's numbers dipped slightly below 3,000 per year in FY 10, FY12, and FY13, but rose to over 3,800 in FY 11 and 3105 in FY14. Quantitative accomplishments: PTTC has maintained its unique structure of a national organization working through Regional Lead Organizations (RLOs) to deliver local, affordable workshops. During the contract period PTTC consolidated from 10 to five regions to increase efficiency, and because no active RLO's would be maintained in the Central and Eastern Gulf Coast regions. RLO's for the regions are located at: Eastern - West Virginia University, (Illinois Geol. Survey., W. Michigan Univ. FY10-12); Midwest created in FY13 - Illinois Geological Survey, W. Michigan University; Midcontinent - University of Kansas, expanded to Houston, TX (2013-14); Rocky Mountain - Colorado School of Mines; Texas/SE New Mexico (FY10-FY11) - Bureau of Economic Geology, Univ. of Texas at Austin; West Coast - Conservation Committee of California O&G Producers.

02 PETROLEUM↗