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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Effects of Heat Release on a Two-Dimensional Reacting Shear Layer

The diffusion controlled binary reaction between initially segregated reactants in a two-dimensional low Mach number mixing layers is studied via numerical simulation. The stoichiometric ratio of the reactants is chosen to be much larger than one, as is typical of hydrocarbon flames in air. This results is a flame that is offset from the main vortical region of the mixing layer. In agreement with experimental observations, the flame remains surprisingly uncontorted during the flow evolution and is not entrained into the mixing layer. The effect of the heat release of the flame on the evolution of the mixing layer is thus similar to the effect of a difference in free-stream density between the two sides of the layer. The resulting baroclinic torque inhibits the familiar rolup and pairing of mixing layer vortices common in constant density flows. This also contributes to the layers inability to entrain the flame. The increase in viscosity caused by the heating of the flame reduces the effective Reynolds number of the flow. But, contrary to what has commonly been suggested, this is not the major reason for the inhibition of the usual large-scale mixing layer structures.

Moser, Robert↗
NASA NTRS2013

Access Control of Web- and Java-Based Applications

Cybersecurity has become a great concern as threats of service interruption, unauthorized access, stealing and altering of information, and spreading of viruses have become more prevalent and serious. Application layer access control of applications is a critical component in the overall security solution that also includes encryption, firewalls, virtual private networks, antivirus, and intrusion detection. An access control solution, based on an open-source access manager augmented with custom software components, was developed to provide protection to both Web-based and Javabased client and server applications. The DISA Security Service (DISA-SS) provides common access control capabilities for AMMOS software applications through a set of application programming interfaces (APIs) and network- accessible security services for authentication, single sign-on, authorization checking, and authorization policy management. The OpenAM access management technology designed for Web applications can be extended to meet the needs of Java thick clients and stand alone servers that are commonly used in the JPL AMMOS environment. The DISA-SS reusable components have greatly reduced the effort for each AMMOS subsystem to develop its own access control strategy. The novelty of this work is that it leverages an open-source access management product that was designed for Webbased applications to provide access control for Java thick clients and Java standalone servers. Thick clients and standalone servers are still commonly used in businesses and government, especially for applications that require rich graphical user interfaces and high-performance visualization that cannot be met by thin clients running on Web browsers

Tso, Kam S.↗
NASA NTRS1973

Lunar powder simulator under lunarlike conditions - Dielectric properties

A powered basalt simulating lunar regolith material was subjected to temperature variations similar to those found in the lunar surface during a lunation. To obtain the dielectric response under simulated lunar conditions, all measurements were made in appropriate vacuums which, in addition, allowed for an evaluation of moisture effects in the powdered sample. It is found that during approximately seven tenths of a lunation the dielectric response of a 5- to 10-cm surface layer should be fairly constant. During the remaining three tenths, it should undergo rapid changes. Changes in the dielectric properties of the surface layer should be controlled by temperature. In the subjacent layers such changes are thought to be controlled by the increasing density of the regolith.

Alvarez, R.↗
NASA NTRS1980

Effects of boundary-layer treatment on cryogenic wind-tunnel controls

Various techniques of realizing the desired boundary layer wall mass removal are considered in order to obtain the desired flow field over the model for various airfoils. The complementary problem of overall thermodynamic equilibrium maintenance created by the side wall boundary layer bleed is also addressed.

Balakrishna, S.↗
NASA NTRS2002

Modelling the effect of diffuse light on canopy photosynthesis in controlled environments

A layered canopy model was used to analyze the effects of diffuse light on canopy gross photosynthesis in controlled environment plant growth chambers, where, in contrast to the field, highly diffuse light can occur at high irradiance. The model suggests that high diffuse light fractions (approximately 0.7) and irradiance (1400 micromoles m-2 s-1) may enhance crop life-cycle canopy gross photosynthesis for hydroponic wheat by about 20% compared to direct light at the same irradiance. Our simulations suggest that high accuracy is not needed in specifying diffuse light fractions in chambers between approximately 0.7 and 1, because simulated photosynthesis for closed canopies plateau in this range. We also examined the effect of leaf angle distribution on canopy photosynthesis under growth chamber conditions, as these distributions determine canopy extinction coefficients for direct and diffuse light. We show that the spherical leaf angle distribution is not suitable for modeling photosynthesis of planophile canopies (e.g., soybean and peanut) in growth chambers. Also, the absorption of the light reflected from the surface below the canopy should generally be included in model simulations, as the corresponding albedo values in the photosynthetically active range may be quite high in growth chambers (e.g., approximately 0.5). In addition to the modeling implications, our results suggest that diffuse light conditions should be considered when drawing conclusions from experiments in controlled environments.

Non-NASA Center↗
NASA NTRS1972

GaAs vapor-grown bipolar transistors.

Discussion of an approach for the fabrication of high-temperature GaAs transistors which is centered on the preparation of n-p-n three-layered structures entirely by a vapor-phase growth technique, as described by Tietjen and Amick (1966). The low growth temperature of approximately 750 C is thought to reduce contamination during crystal growth and to contribute to the reasonably high minority-carrier lifetimes obtained for the vapor-grown p-n junctions. The fact that impurity concentrations and layer thicknesses can be precisely controlled for epitaxial layers as thin as 1 micrometer is an important feature of this growth technique.

Nuese, C. J.↗
DOE OSTI2025

Reactor System Facility Modification to Detect Compromised Human Machine Interfaces

This study focuses on a multi-layered Industrial Control System (ICS)/Operational Technology (OT) security architecture to aid in the discovery and mitigation of compromised Human Machine Interface (HMI)/Instrumentation & Control (I&C) based systems for modifying a prototypical reactor condition test facility called the Flowing Autoclave System (FAS) at Idaho National Laboratory (INL). This is achieved through a three-layered combination of network security solutions, hash-based algorithms, and blockchain technologies. Hash algorithms are mathematical functions used to generate a predetermined set of fixed-length values. They are widely used in computer security to verify the integrity of system information and data, both on a local network and the wider internet. Even small amounts of unauthorized system modification will cause the hash algorithm to output a set of characters that deviate significantly from its original value. Assisting secure hash functions, blockchain technology is a secure and distributed technology used to provide an immutable set of records replicated on all devices within a decentralized network. Blockchain offers a cost-effective solution to detect system compromise by providing a traceable breadcrumb trail of all network activity and data modification happening on a system. If both are used in conjunction with network monitoring tools, the integration of this three-pronged approach can become an asset in detecting suspected system compromises before any real damage can occur.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2026

Embedded EPICS server for PowerPMAC motion controllers

An embedded server layer of Experimental Physics and Industrial Control System (EPICS) for PowerPMAC motion controllers has been developed and deployed at two undulator beamlines of the National Institute of General Medical Sciences and the National Cancer Institute (GM/CA) Structural Biology Facility at the Advanced Photon Source (APS). This compact, open source solution makes the power and versatility of PowerPMAC motion controls directly accessible to distributed EPICS clients. At GM/CA the system controls about 200 servo and stepper motors — both encoded and unencoded — and multiple digital and analog I/O accessories. The server stack comprises two sublayers: a lower-level driver and database that communicates directly with PowerPMAC, and a facility-specific soft sublayer built on top. The paper describes installing EPICS on PowerPMAC, the implementation of both layers and client examples, including on-the-fly scanning.

EPICS↗
DOE OSTI2021

Molecular Layer Deposition of Crosslinked Polymeric Lithicone for Superior Lithium Metal Anodes

In this work, we for the first time developed a novel lithium-containing crosslinked polymeric material, a lithicone that enables excellent protection effects over lithium (Li) metal anodes. This new lithicone was synthesized via an accurately controllable molecular layer deposition (MLD) process, in which lithium tert -butoxide (LTB) and glycerol (GL) were used as precursors. The resultant LiGL lithicone was analyzed using a suite of characterizations. Furthermore, we found that the LiGL thichicone could serve as an exceptional polymeric protection film over Li metal anodes. Our experimental data revealed that the Li electrodes coated by this LiGL lithicone can achieve a superior cycling stability, accounting for an extremely long cyclability of >13,600 Li-stripping/plating cycles and having no failures so far in Li/Li symmetric cells at a current density of 5 mA/cm 2 and an areal capacity of 1 mAh/cm 2 . We found that, with a sufficient protection by this LiGL coating, Li electrodes could realize long-term stable cyclability with little formation of Li dendrites and solid electrolyte interphase. This novel LiGL represents a facile and effective solution to the existing issues of Li anodes and potentially paves a technically feasible route for lithium metal batteries.

Meng, Xiangbo↗
NASA NTRS2003

Control of Thermal Convection in Layered Fluids Using Magnetic fields

Immiscible fluid layers are found in a host of applications ranging from materials processing, for example the use of encapsulants in float zone crystal growth technique and a buffer layer in industrial Czochralski growth of crystals to prevent Marangoni convection, to heat transfer phenomena in day-to-day processes like the presence of air pockets in heat exchangers. In the microgravity and space processing realm, the exploration of other planets requires the development of enabling technologies in several fronts. The reduction in the gravity level poses unique challenges for fluid handling and heat transfer applications. The present work investigates the efficacy of controlling thermal convective flow using magnetic fluids and magnetic fields. The setup is a two-layer immiscible liquids system with one of the fluids being a diluted ferrofluid (super paramagnetic nano particles dispersed in carrier fluid). Using an external magnetic field one can essentially dial in a volumetric force - gravity level, on the magnetic fluid and thereby affect the system thermo-fluid behavior. The paper will describe the experimental and numerical modeling approach to the problem and discuss results obtained to date.

Ramachandran, N.↗
DOE OSTI2024

Steam‐Assisted Selective CO 2 Hydrogenation to Ethanol over Ru−In Catalysts

Abstract Multicomponent catalysts can be designed to synergistically combine reaction intermediates at interfacial active sites, but restructuring makes systematic control and understanding of such dynamics challenging. We here unveil how reducibility and mobility of indium oxide species in Ru‐based catalysts crucially control the direct, selective conversion of CO 2 to ethanol. When uncontrolled, reduced indium oxide species occupy the Ru surface, leading to deactivation. With the addition of steam as a mild oxidant and using porous polymer layers to control In mobility, Ru−In 2 O 3 interface sites are stabilized, and ethanol can be produced with superior overall selectivity (70 %, rest CO). Our work highlights how engineering of bifunctional active ensembles enables cooperativity and synergy at tailored interfaces, which unlocks unprecedented performance in heterogeneous catalysts.

Zhou, Chengshuang↗
DOE OSTI2024

Steam-Assisted Selective CO 2 Hydrogenation to Ethanol over Ru–In Catalysts

Multicomponent catalysts can be designed to synergistically combine reaction intermediates at interfacial active sites, but restructuring makes systematic control and understanding of such dynamics challenging. In this work, we unveil how reducibility and mobility of indium oxide species in Ru-based catalysts crucially control the direct, selective conversion of CO 2 to ethanol. When uncontrolled, reduced indium oxide species occupy the Ru surface, leading to deactivation. With the addition of steam as a mild oxidant and using porous polymer layers to control In mobility, Ru–In 2 O 3 interface sites are stabilized, and ethanol can be produced with superior overall selectivity (70 %, rest CO). Our work highlights how engineering of bifunctional active ensembles enables cooperativity and synergy at tailored interfaces, which unlocks unprecedented performance in heterogeneous catalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Atomically engineered cobaltite layers for robust ferromagnetism

Emergent phenomena at heterointerfaces are directly associated with the bonding geometry of adjacent layers. Effective control of accessible parameters, such as the bond length and bonding angles, offers an elegant method to tailor competing energies of the electronic and magnetic ground states. In this study, we construct unit-thick syntactic layers of cobaltites within a strongly tilted octahedral matrix via atomically precise synthesis. The octahedral tilt patterns of adjacent layers propagate into cobaltites, leading to a continuation of octahedral tilting while maintaining substantial misfit tensile strain. These effects induce severe rumpling within an atomic plane of neighboring layers, further triggering the electronic reconstruction between the splitting orbitals. First-principles calculations reveal that the cobalt ions transit to a higher spin state level upon octahedral tilting, resulting in robust ferromagnetism in ultrathin cobaltites. This work demonstrates a design methodology for fine-tuning the lattice and spin degrees of freedom in correlated quantum heterostructures by exploiting epitaxial geometric engineering.

36 MATERIALS SCIENCE↗
NASA NTRS1975

Evaluation of some control-volume techniques for analysis of shock-boundary layer interactions in supersonic inlets

Various control-volume models used to analyze the shock boundary layer bleed interaction were investigated. The bleed assumptions of the models and their influence on the analytical solutions are discussed. The results of the analysis using these models are compared with experimental boundary-layer data taken in a supersonic inlet. The experimental Mach number upstream of the interaction was 1.66, and the oblique-shock pressure ratio was 1.33. The boundary layer data included bleed flow rates up to approximately 0.6 of the upstream boundary layer mass flow rate. The first model assumed the bleed was removed from the control volume with a momentum that was characterized by a pressure intermediate between the upstream and downstream pressures. The second model assumed the control volume was bounded by a streamline dividing the bleed and residual flows and eliminated the need to specify the momentum of the bleed flow. Comparison of the results using the models showed that specifying the bleed pressure in one model was equivalent to specifying the pressure along the dividing streamline in the other.

Hingst, W. R.↗
NASA NTRS2017

Numerical Experiments in Error Control for Sound Propagation Using a Damping Layer Boundary Treatment

This paper presents results from numerical experiments for controlling the error caused by a damping layer boundary treatment when simulating the propagation of an acoustic signal from a continuous pressure source. The computations are with the 2D Linearized Euler Equations (LEE) for both a uniform mean flow and a steady parallel jet. The numerical experiments are with algorithms that are third, fifth, seventh and ninth order accurate in space and time. The numerical domain is enclosed in a damping layer boundary treatment. The damping is implemented in a time accurate manner, with simple polynomial damping profiles of second, fourth, sixth and eighth power. At the outer boundaries of the damping layer the propagating solution is uniformly set to zero. The complete boundary treatment is remarkably simple and intrinsically independant from the dimension of the spatial domain. The reported results show the relative effect on the error from the boundary treatment by varying the damping layer width, damping profile power, damping amplitude, propagtion time, grid resolution and algorithm order. The issue that is being addressed is not the accuracy of the numerical solution when compared to a mathematical solution, but the effect of the complete boundary treatment on the numerical solution, and to what degree the error in the numerical solution from the complete boundary treatment can be controlled. We report maximum relative absolute errors from just the boundary treatment that range from O[10-2] to O[10-7].

Algorithm↗
NASA NTRS2017

Numerical Experiments in Error Control for Sound Propagation Using a Damping Layer Boundary Treatment

This paper presents results from numerical experiments for controlling the error caused by a damping layer boundary treatment when simulating the propagation of an acoustic signal from a continuous pressure source. The computations are with the 2D Linearized Euler Equations (LEE) for both a uniform mean flow and a steady parallel jet. The numerical experiments are with algorithms that are third, fifth, seventh and ninth order accurate in space and time. The numerical domain is enclosed in a damping layer boundary treatment. The damping is implemented in a time accurate manner, with simple polynomial damping profiles of second, fourth, sixth and eighth power. At the outer boundaries of the damping layer the propagating solution is uniformly set to zero. The complete boundary treatment is remarkably simple and intrinsically independant from the dimension of the spatial domain. The reported results show the relative effect on the error from the boundary treatment by varying the damping layer width, damping profile power, damping amplitude, propagtion time, grid resolution and algorithm order. The issue that is being addressed is not the accuracy of the numerical solution when compared to a mathematical solution, but the effect of the complete boundary treatment on the numerical solution, and to what degree the error in the numerical solution from the complete boundary treatment can be controlled. We report maximum relative absolute errors from just the boundary treatment that range from O[10-2] to O[10-7].

Computational Aeroacoustics↗
DOE OSTI2026

Engineering Controls Database

Cyber-Informed Engineering (CIE) addresses the reality that cyber attacks on engineered systems can have consequences far beyond data loss or disruption of digital networks. When control systems are compromised, safety, reliability, and performance of the physical process itself may be threatened. This database is meant to establish clear examples and guidance for defining and applying engineered controls in CIE. It explains what engineered controls are, how they differ from information security measures, and how they are integrated into system design. The goal is to ensure that resilience is engineered into systems from the outset. Unlike cybersecurity protections that defend the digital layer, engineered controls act directly at the physical and algorithmic levels to guarantee that unacceptable consequences are prevented or limited. CIE keeps the consequences of a cyber attack from impacting the safety, reliability, and performance of engineered systems.

Source record↗