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NASA NTRS1995

Dynamic properties of the human vestibulo-ocular reflex during head rotations in roll

We investigated the dynamic properties of the human vestibulo-ocular reflex (VOR) during roll head rotations in three human subjects using the magnetic search coil technique. In the first of two experiments, we quantify the behavior of the ocular motor plant in the torsional plane. The subject's eye was mechanically displaced into intorsion, extorsion or abduction, and the dynamic course of return of the eye to its resting position was measured. The mean predominant time constants of return were 210 msec from intorsion, 83 msec from extorsion, and 217 msec from abduction, although there was considerable variability of results from different trials and subjects. In the second experiment, we quantify the efficacy of velocity-to-position integration of the vestibular signal. Position-step stimuli were used to test the torsional or horizontal VOR, being applied with subjects heads erect or supine. After a torsional position-step, the eye drifted back to its resting position, but after a horizontal position-step the eye held its new horizontal position. To interpret these responses we used a simple model of the VOR with parameters of the ocular motor plant set to values determined during Exp 1. The time constant of the velocity-to-position neural integrator was smaller (typically 2 sec) in the torsional plane than in the horizontal plane (> 20 sec). No disconjugacy of torsional eye movements was observed. Thus, the dynamic properties of the VOR in roll differ significantly from those of the VOR in yaw, reflecting different visual demands placed on this reflex in these two planes.

NASA Discipline Neuroscience↗

DOE OSTI2022

Dynamic response of photorespiration in fluctuating light environments

Abstract Photorespiration is a dynamic process that is intimately linked to photosynthetic carbon assimilation. There is a growing interest in understanding carbon assimilation during dynamic conditions, but the role of photorespiration under such conditions is unclear. In this review, we discuss recent work relevant to the function of photorespiration under dynamic conditions, with a special focus on light transients. This work reveals that photorespiration is a fundamental component of the light induction of assimilation where variable diffusive processes limit CO2 exchange with the atmosphere. Additionally, metabolic interactions between photorespiration and the C3 cycle may help balance fluxes under dynamic light conditions. We further discuss how the energy demands of photorespiration present special challenges to energy balancing during dynamic conditions. We finish the review with an overview of why regulation of photorespiration may be important under dynamic conditions to maintain appropriate fluxes through metabolic pathways related to photorespiration such as nitrogen and one-carbon metabolism.

Plant Sciences↗

DOE OSTI2020

DAQExpert the service to increase CMS data-taking efficiency

The Data Acquisition (DAQ) system of the Compact Muon Solenoid (CMS) experiment at the LHC is a complex system responsible for the data readout, event building and recording of accepted events. Its proper functioning plays a critical role in the data-taking efficiency of the CMS experiment. In order to ensure high availability and recover promptly in the event of hardware or software failure of the subsystems, an expert system, the DAQ Expert, has been developed. It aims at improving the data taking efficiency, reducing the human error in the operations and minimising the on-call expert demand. Introduced in the beginning of 2017, it assists the shift crew and the system experts in recovering from operational faults, streamlining the post mortem analysis and, at the end of Run 2, triggering fully automatic recovery without human intervention. DAQ Expert analyses the real-time monitoring data originating from the DAQ components and the high-level trigger updated every few seconds. It pinpoints data flow problems, and recovers them automatically or after given operator approval. We analyse the CMS downtime in the 2018 run focusing on what was improved with the introduction of automated recovery; present challenges and design of encoding the expert knowledge into automated recovery jobs. Furthermore, we demonstrate the web-based, ReactJS interfaces that ensure an effective cooperation between the human operators in the control room and the automated recovery system. We report on the operational experience with automated recovery.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2021

SYMBIOSYS: A Methodology for Performance Analysis of Composable HPC Data Services

Microservices are a powerful new way of building, customizing, and deploying distributed services owing to their flexibility and maintainability. Several large-scale distributed platforms have emerged to serve the growing needs of data-centric workloads and services in commercial computing. Concurrently, high-performance computing (HPC) systems and software are rapidly evolving to meet the demands of diversified applications and heterogeneity. The interplay of hardware factors, software configuration parameters, and the flexibility offered with a microservice architecture makes it nontrivial to estimate the optimal service instantiation for a given application workload. Further, this problem is exacerbated when considering that these services operate in a dynamic and heterogeneous HPC environment. An optimally integrated service can be vastly more performant than a haphazardly integrated one. Existing performance tools for HPC either fail to understand the request-response model of communication inherent to microservices or they operate within a narrow scope, limiting the insight that can be gleaned from employing them in isolation. We propose a methodology for integrated performance analysis of HPC microservices frameworks and applications called SYMBIOSYS. We describe its design and implementation within the context of the Mochi framework. This integration is achieved by combining distributed callpath profiling and tracing with a performance data exchange strategy that collects fine-grained, low-level metrics from the RPC communication library and network layers. The result is a portable, low-overhead performance analysis setup that provides a holistic profile of the dependencies among microservices and how they interact with the Mochi RPC software stack. Using HEPnOS, a production-quality Mochi data service, we demonstrate the low-overhead operation of SYMBIOSYS at scale and use it to identify the root causes of poorly performing service configurations.

microservices↗

NASA NTRSDate not supplied

TPS Technology Status on Enabling New Frontiers Sample Return Missions from Moon, Asteroids and Comets and Probe Missions to Saturn and Uranus

STMD and SMD investment in TPS technology development such as Heatshield for Extreme Entry Environment (HEEET), 3-D woven Mid-Density Carbon Phenolic (3MDCP) and Conformal PICA over the past decade in response the the Decadal Committee Recommendation (2012). 3MDCP, a variant of HEEET, is baselined as the TPS for MSR, HEEET is enabling the Rocket Lab mission to Venus and Conformal PICA enabled VARDA as the heat shield TPS for their sample return capsule Winnebago-1. In the meantime, PICA, the TPS that enabled Stardust and OSIRIS-REx has atrophied. While these are success stories, upcoming NF-5/6 AO is anticipated to have multiple proposals that may be more demanding for sample return missions from Moon, Asteroids and Comets, and in addition probe missions to Saturn and UOP . This poster will address the state-of-the-art TPS for NF-5/6 in-situ and sample return missions, and for the UOP flagship mission. The poster will focus on steps that need to be taken to both advance and sustain NASA developed TPS and be ready to enable NF-5/6 and Flagship missions.

Todd White↗

DOE OSTI2021

Nonlinear dynamics of topological Dirac fermions in 2D spin-orbit coupled materials

Abstract The graphene family materials are two-dimensional staggered monolayers with a gapped energy band structure due to intrinsic spin-orbit coupling. The mass gaps in these materials can be manipulated on-demand via biasing with a static electric field, an off-resonance circularly polarized laser, or an exchange interaction field, allowing the monolayer to be driven through a multitude of topological phase transitions. We investigate the dynamics of spin-orbit coupled graphene family materials to unveil topological phase transition fingerprints embedded in the nonlinear regime and show how these signatures manifest in the nonlinear Kerr effect and in third-harmonic generation processes. We show that the resonant nonlinear spectral response of topological fermions can be traced to specific Dirac cones in these materials, enabling characterization of topological invariants in any phase by detecting the cross-polarized component of the electromagnetic field. By shedding light on the unique processes involved in harmonic generation via topological phenomena our findings open an encouraging path towards the development of novel nonlinear systems based on two-dimensional semiconductors of the graphene family.

36 MATERIALS SCIENCE↗

NASA NTRS1972

Seventeen Ketogenic steroids excretion in crewmen in a 90-day manned test of an advanced regenerative life support system

Seventeen KGS (17-Ketogenic steroids) and Na/K were determined in 19 urine specimens collected by each of 4 crewmen during the 90-day test. The specimens represented 10% aliquots of 24-hour collections stored frozen onboard the simulator until passthrough. Electrolytes were analyzed immediately after sample passthrough while the steroids were determined post-test on aliquots of the original sample held at 203 K. Steroid data was corrected for body weight and also for analytical variation in the laboratory urine pool control. Long-term nonspecific responses to low-level stress appear to be reflected by the individual and group mean 17-KGS excretion patterns. The first 39 and the last 20 days of the test were significantly different--and presumably more stressful to the crew--than the period from days 39 to 67. Reduction of adrenocortical function during the mid-test phase is attributed to either an adaptation to chronic or intermittent stress or was the result of an actual reduction in the operational demands of the test during this time. Most remarkable of the metabolic findings is the prevalance of high Na/K ratios and an abrupt peak on day 74 for all 4 crewmen.

Myers, D. J.↗

NASA NTRS1993

Magellan attitude control mission operations

From the Martin Marietta Astronautics Group base in Denver, Colorado, spacecraft engineers have been operating the Magellan spacecraft for the past three and one half years, along with the Jet Propulsion Laboratory, for NASA. The spacecraft team in Denver is responsible for the health of the vehicle, from command generation to evaluation of engineering telemetry. Operation of the spacecraft's Attitude and Articulation Control Subsystem (AACS) has specifically posed several in-flight challenges. This system must provide accurate pointing of the spacecraft throughout each 3.2 hour orbit which typically consists of 5 - 9 discrete maneuvers. Preparation of bi-weekly command sequences, monitoring execution, and trending of subsystem performance is of paramount importance, but in-flight anomalies have also demanded the attention of AACS engineers. Anomalies are often very interesting and challenging aspects of a project, and the Magellan mission was no exception. From the first unsuccessful attempts to perform a starscan, to spacecraft safing events, much has been experienced to add to the `lessons learned' from this mission. Many of Magellan's in-flight experiences, anomalies, and their resolutions are highlighted in this paper.

Dukes, Eileen M.↗

DOE OSTI2026

Computational capacity in hydrodynamic real-time hybrid simulation applied to simulate the dynamic response of floating offshore wind turbines

Real-time hybrid simulation (RTHS) mitigates similitude distortions in model-scale tests of floating offshore wind turbines (FOWTs) by coupling physical experiments with numerical models in real time. The coupling requires faster-than-real-time numerical computations to satisfy temporal similitude with the physical experiment, presenting a bottleneck for using more complex numerical models in RTHS. This paper presents a hydrodynamic-RTHS (hydro-RTHS) framework for FOWTs that simulates the hydrodynamics physically and the aerodynamics numerically with sensor feedback from the physical testing. The framework adapts the three-loop hardware architecture to leverage greater computational resources and mitigate strict temporal requirements, enabling more computationally demanding numerical analyses in hydro-RTHS. The three-loop hardware architecture integrates multiple machines, each dedicated to either numerical analysis or RTHS controls, with a rate-transition algorithm to synchronize the tasks executed across the different machine processors. Virtual and physical tests verified and validated the hydro-RTHS framework, respectively. The ”virtual” tests, which approximates the physical domain numerically, verified the RTHS framework with respect to a numerical full-scale complete FOWT model simulated in the open-source software, OpenFAST. The virtual tests were able to maintain comparable control signals while enabling greater computational resources for the numerical calculations. Real-world physical tests demonstrated that the hydro-RTHS framework computes aerodynamic forces similar to the complete OpenFAST model, validating the hydro-RTHS framework using the three-loop hardware architecture. Findings show that the hydro-RTHS framework with the three-loop hardware architecture is computationally efficient, with reserve capacity to simulate more complex problems due to the customized software, hardware, and rate-transition algorithm.

17 WIND ENERGY↗

DOE OSTI2025

Autonomous phase mapping of gold nanoparticles synthesis with differentiable models of spectral shape

Autonomous experimentation–or self-driving labs–offers a systematic approach to accelerate materials discovery by integrating automated synthesis, characterization, and data-driven decision-making. We present a closed-loop workflow for the on-demand synthesis and structural characterization of colloidal gold nanoparticles, enabling direct mapping from composition to nanoscale structure. Our framework leverages differentiable models of spectral shape to address two central tasks in self-driving labs: (a) phase mapping, or identifying compositional regions with distinct structural behavior; and (b) material retrosynthesis, or optimizing compositions for target structure. Using functional data analysis, we develop a data-driven model with generative pre-training, active learning, and high-throughput experiments to predict spectral responses across composition space. We demonstrate the approach on seed-mediated growth of gold nanoparticles, showcasing its ability to extract design rules, reveal secondary interactions, and efficiently navigate morphology space. Gradient-based optimization of the models enables inverse design, making this a unified platform.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Temporal dynamics of free‐living nitrogen fixation in the switchgrass rhizosphere

Abstract Free‐living nitrogen fixation (FLNF) represents an important terrestrial N source and is gaining interest for its potential to contribute plant available N to bioenergy cropping systems. Switchgrass, a cellulosic bioenergy crop, may be particularly reliant on FLNF when grown on low N systems, like marginal lands. However, the potential contributions of FLNF to switchgrass as well as the controls on this process are not well understood. In this study, we evaluated drivers of FLNF rates and N‐fixing microbial (diazotrophic) community composition in field‐grown switchgrass systems over two growing seasons with high temporal sampling. We found that climate variables are strong drivers of FLNF rates in switchgrass systems, compared to other environmental and biological factors including soil nutrients and diazotrophic community composition. Increased soil moisture availability generally promoted FLNF rates, but extreme rainfall events were detrimental. These climate‐related responses suggest a potential for loss of FLNF‐derived N contributions under projected climate shifts. We found a significant, but weak correlation between diazotrophic community composition and FLNF rates. We also observed a significant shift in the diazotrophic community composition between 2017 and 2018 and similarly measured a significant difference in FLNF rates between growing seasons. Lastly, we found that seasonal FLNF N contributions, based on measurement with high temporal resolution, has the potential to meet up to 80% of switchgrass N demands suggesting that FLNF measurements extrapolated from fewer time points or locations may underestimate these potential N contributions.

59 BASIC BIOLOGICAL SCIENCES↗

NASA NTRS1976

Definition of performance specifications for automated Analytical Electrophoresis Facility (AAEF)

In order to provide specifications for the automated Analytical Electrophoresis Facility (AAEF) that would satisfy the broadest variety of demands of a future user community, a survey was carried out of all those people who were identified as having published papers on cell electrophoresis in the past four years. A computer search was conducted of the relevant literature from which a list of 87 investigators was derived and defined as the user community for purposes of the mailing. A questionnaire was developed covering the areas of performance which required definition which was subsequently circulated to the user community. Based on the response to this survey performance specifications were assembled.

Brooks, D. E.↗

NASA NTRS1987

Dynamic stability and handling qualities tests on a highly augmented, statically unstable airplane

Initial envelope clearance and subsequent flight testing of a new, fully augmented airplane with an extremely high degree of static instability can place unusual demands on the flight test approach. Previous flight test experience with these kinds of airplanes is very limited or nonexistent. The safe and efficient flight testing may be further complicated by a multiplicity of control effectors that may be present on this class of airplanes. This paper describes some novel flight test and analysis techniques in the flight dynamics and handling qualities area. These techniques were utilized during the initial flight envelope clearance of the X-29A aircraft and were largely responsible for the completion of the flight controls clearance program without any incidents or significant delays.

Gera, Joseph↗

NASA NTRS2006

Analytical, Numerical, and Experimental Investigation on a Non-Contact Method for the Measurements of Creep Properties of Ultra-High-Temperature Materials

Responsive access to space requires re-use of components such as rocket nozzles that operate at extremely high temperatures. For such applications, new ultra-hightemperature materials that can operate over 2,000 C are required. At the temperatures higher than the fifty percent of the melting temperature, the characterization of creep properties is indispensable. Since conventional methods for the measurement of creep is limited below 1,700 C, a new technique that can be applied at higher temperatures is strongly demanded. This research develops a non-contact method for the measurement of creep at the temperatures over 2,300 C. Using the electrostatic levitator in NASA MSFC, a spherical sample was rotated to cause creep deformation by centrifugal acceleration. The deforming sample was captured with a digital camera and analyzed to measure creep deformation. Numerical and analytical analyses have also been conducted to compare the experimental results. Analytical, numerical, and experimental results showed a good agreement with one another.

Lee, Jonghyun↗

DOE OSTI2020

PV-Fed Smart Inverters for Mitigation of Voltage and Frequency Fluctuations in Islanded Microgrids

The presence of low-inertia distributed generation (DG) units makes islanded microgrids vulnerable to voltage and frequency variations. Besides, the considerable difference between the inertia of synchronous-based and inverter-based DGs results in a power imbalance between supply and demand during abnormal conditions. As a result, both voltage and frequency of microgrid ac-bus start oscillating which might have severe consequences such as blackouts. This paper deploys the traditional controller of photovoltaic (PV) units to improve the dynamic behavior of islanded microgrids by suppressing the voltage and frequency fluctuations. To this end, an adaptive piecewise droop (APD) characteristic is proposed and employed in PV units to attain a faster balance between generation and consumption during transients, leading to an enhanced frequency response. Besides, the reactive-power control loop is equipped with a droop characteristic which enables the PV units to inject/absorb reactive power during transients and participate in voltage-profile enhancement of the system. Case study results are presented using PSCAD/EMTDC to confirm the validity of proposed method in improving the dynamics of islanded microgrids.

Pilehvar, Mohsen S.↗

DOE OSTI2024

A Review of the Multiple-Readout Concept and Its Application in an Integrally Active Calorimeter

A comprehensive multi-jet physics program is anticipated for experiments at future colliders. Key physics processes necessitate detectors that can distinguish signals from W and Z bosons and the Higgs boson. Typical examples include channels with or pairs and processes involving new physics in those cases where neutral particles must be disentangled from charged ones due to the presence of W or Z bosons in their final states. Such a physics program demands calorimetric energy resolution at or beyond the limits of traditional calorimetric techniques. Multiple-readout calorimetry, which aims to reduce fluctuations in energy measurements of hadronic showers, is a promising approach. The first part of this article reviews dual- and triple-readout calorimetry within a mathematical framework describing the underlying compensating mechanism. The second part proposes a potential implementation using an integrally active and total absorption detector. This model serves as the basis for several Monte Carlo studies, illustrating how the response of a multiple-readout calorimeter depends on construction parameters. Among the layouts considered, one configuration operating in triple-readout mode shows the potential to achieve an energy resolution approaching .

47 OTHER INSTRUMENTATION↗

NASA NTRS2014

Global Warming and 21st Century Drying

Global warming is expected to increase the frequency and intensity of droughts in the twenty-first century, but the relative contributions from changes in moisture supply (precipitation) versus evaporative demand (potential evapotranspiration; PET) have not been comprehensively assessed. Using output from a suite of general circulation model (GCM) simulations from phase 5 of the Coupled Model Intercomparison Project, projected twentyfirst century drying and wetting trends are investigated using two offline indices of surface moisture balance: the Palmer Drought Severity Index (PDSI) and the Standardized Precipitation Evapotranspiration Index (SPEI). PDSI and SPEI projections using precipitation and Penman- Monteith based PET changes from the GCMs generally agree, showing robust cross-model drying in western North America, Central America, the Mediterranean, southern Africa, and the Amazon and robust wetting occurring in the Northern Hemisphere high latitudes and east Africa (PDSI only). The SPEI is more sensitive to PET changes than the PDSI, especially in arid regions such as the Sahara and Middle East. Regional drying and wetting patterns largely mirror the spatially heterogeneous response of precipitation in the models, although drying in the PDSI and SPEI calculations extends beyond the regions of reduced precipitation. This expansion of drying areas is attributed to globally widespread increases in PET, caused by increases in surface net radiation and the vapor pressure deficit. Increased PET not only intensifies drying in areas where precipitation is already reduced, it also drives areas into drought that would otherwise experience little drying or even wetting from precipitation trends alone. This PET amplification effect is largest in the Northern Hemisphere mid-latitudes, and is especially pronounced in western North America, Europe, and southeast China. Compared to PDSI projections using precipitation changes only, the projections incorporating both precipitation and PET changes increase the percentage of global land area projected to experience at least moderate drying (PDSI standard deviation of < or = -1) by the end of the twenty-first century from 12 to 30 %. PET induced moderate drying is even more severe in the SPEI projections (SPEI standard deviation of > or = -1; 11 to 44 %), although this is likely less meaningful because much of the PET induced drying in the SPEI occurs in the aforementioned arid regions. Integrated accounting of both the supply and demand sides of the surface moisture balance is therefore critical for characterizing the full range of projected drought risks tied to increasing greenhouse gases and associated warming of the climate system.

moisture↗

DOE OSTI2024

The hydrogen economy can reduce costs of climate change mitigation by up to 22%

In response to the urgent need to mitigate climate change via net-zero targets, many nations are renewing their interest in clean hydrogen as a net-zero energy carrier. Although clean hydrogen can be directly used in various sectors for deep decarbonization, the relatively low energy density and high production costs have raised doubts as to whether clean hydrogen development is worthwhile. Here, we improve on the GCAM model by including a more comprehensive and detailed representation of clean hydrogen production, distribution, and demand in all sectors of the global economy and simulate 25 scenarios to explore the cost-effectiveness of integrating clean hydrogen into the global energy system. We show that, due to costly technical obstacles, clean hydrogen can only provide 3%–9% of the 2050 global final energy use. Nevertheless, clean hydrogen deployment can reduce overall energy decarbonization costs by 15%–22%, mainly via powering “hard-to-electrify” sectors that would otherwise face high decarbonization expenditures. Our work provides practical references for cost-effective clean hydrogen planning.

08 HYDROGEN↗