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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 811 records · Page 45
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Novel improved PMR polyimides

The development of a class of high-temperature-resistant resins known as PMR polyimides has been reported by Serafini et al. (1972). Serafini and Vannucci (1975) found that the lower formulated molecular weight (FMW) compositions exhibited increased resin flow, but with some sacrifice in elevated temperature thermo-oxidative stability. Vannucci (1977) reported that the resin flow characteristics of the PMR composition having an FMW of 1500 could be varied by controlling the degree of resin advancement or imidization. The current investigation is concerned with an alternative approach to obtain improved flow PMR polyimides without sacrificing the desirable thermo-oxidative characteristics. The new approach is based on the utilization of a chemically compatible flow modifying agent. This agent is N-phenylnadimide (PN). The determination of the processing characteristics and properties of PN modified PMR/Celion 6000 composites is discussed.

Pater, R. H.↗
NASA NTRS1985

Recharging Batteries Chemically

Iron/air batteries recharged chemically by solution of strong base in alcohol or by basic alcohol solution of reducing agent. Although method still experimental, it has potential for batteries in electric automobiles or as energy system in remote applications. Also used in quiet operations where noise or infrared signature of diesel engine is not desired.

Williams, R. M.↗
NASA NTRS1989

Blackboard system generator (BSG) - An alternative distributed problem-solving paradigm

A status review is presented for a generic blackboard-based distributed problem-solving environment in which multiple-agent cooperation can be effected. This environment is organized into a shared information panel, a chairman control panel, and a metaplanning panel. Each panel contains a number of embedded AI techniques that facilitate its operation and that provide heuristics for solving the underlying team-agent decision problem. The status of these panels and heuristics is described along with a number of robustness considerations. The techniques for each of the three panels and for four sets of paradigm-related advances are described, along with selected results from classroom teaching experiments and from three applications.

Silverman, Barry G.↗
NASA NTRS1989

Problems in water recycling for Space Station Freedom and long duration life support

A biologically-enhanced, physical/chemical terminal water treatment testbed for the Space Station Freedom is proposed. Recycled water requirements for human, animal, plant and/or combined crews for long duration space missions are discussed. An effective terminal treatment method for recycled water reclamation systems that is based on using granular activated carbon as the principal active agent and the controls of microbial contamination and growth within recycled water systems are examined. The roles of plants in water recycling within CELSS is studied.

Janik, D. S.↗
NASA NTRS1993

An oxygen pressure sensor using surface acoustic wave devices

Surface acoustic wave (SAW) piezoelectric devices are finding widespread applications in many arenas, particularly in the area of chemical sensing. We have developed an oxygen pressure sensor based on coating a SAW device with an oxygen binding agent which can be tailored to provide variable sensitivity. The coating is prepared by dissolving an oxygen binding agent in a toluene solution of a copolymer which is then sprayed onto the surface of the SAW device. Experimental data shows the feasibility of tailoring sensors to measure the partial pressure of oxygen from 2.6 to 67 KPa (20 to 500 torr). Potential applications of this technology are discussed.

Leighty, Bradley D.↗
NASA NTRS2005

Vapor Transport of ZnO in Closed Ampoules

Vapor transport of ZnO by PVT and CVT using carbon, carbon monoxide, and hydrogen as the transport agents was studied. Theoretical calculations of the mass flux were based on equilibrium thermodynamics and 1-D diffusional mass transport. Experimental results were found to be consistent with theoretical predictions. NO apparent kinetic limitations to sublimation were observed. Slow reaction of carbon with ZnO source was found.

Palosz, Witold↗
NASA NTRS2011

Standardization of Spore Inactivation Method for PMA-PhyloChip Analysis

In compliance with the Committee on Space Research (COSPAR) planetary protection policy, National Aeronautics and Space Administration (NASA) monitors the total microbial burden of spacecraft as a means for minimizing the inadvertent transfer of viable contaminant microorganisms to extraterrestrial environments (forward contamination). NASA standard assay-based counts are used both as a proxy for relative surface cleanliness and to estimate overall microbial burden as well as to assess whether forward planetary protection risk criteria are met for a given mission, which vary by the planetary body to be explored and whether or not life detection missions are present. Despite efforts to reduce presence of microorganisms from spacecraft prior to launch, microbes have been isolated from spacecraft and associated surfaces within the extreme conditions of clean room facilities using state of the art molecular technologies. Development of a more sensitive method that will better enumerate all viable microorganisms from spacecraft and associated surfaces could support future life detection missions. Current culture-based (NASA standard spore assay) and nucleic-acid-based polymerase chain reaction (PCR) methods have significant shortcomings in this type of analysis. The overall goal of this project is to evaluate and validate a new molecular method based on the use of a deoxyribonucleic acid (DNA) intercalating agent propidium monoazide (PMA). This is used in combination with DNA microarray (PhyloChip) which has been shown to identify very low levels of organisms on spacecraft associated surfaces. PMA can only penetrate the membrane of dead cells. Once penetrated, it intercalates the DNA and, upon photolysis using visible light it produces stable DNA monoadducts. This allows DNA to be unavailable for further PCR analysis. The specific aim of this study is to standardize the spore inactivation method for PMA-PhyloChip analysis. We have used the bacterial spores Bacillus subtilis 168 (standard laboratory isolate) as a test organism.

spore inactivation↗
DOE OSTI2022

A Hybrid Reinforcement Learning-MPC Approach for Distribution System Critical Load Restoration: Preprint

This paper proposes a hybrid control approach for distribution system critical load restoration, combining deep reinforcement learning (RL) and model predictive control (MPC) aiming at maximizing total restored load following an extreme event. RL determines a policy for quantifying operating reserve requirements, thereby hedging against uncertainty, while MPC models grid operations incorporating RL policy actions, i.e., the reserve requirement, renewable (wind and solar) power predictions, and load demand forecasts. We formulate the reserve requirement determination problem as a sequential decision making problem based on the Markov Decision Process (MDP) and design an RL learning environment based on the OpenAI Gym framework and MPC. The RL agent reward and MPC objective function aim to maximize and monotonically increase total restored load and minimize load shedding and renewable power curtailment. The RL algorithm is trained off-line using historical forecast of renewable generation and load demand. The method is tested using a modified IEEE 13-bus distribution test feeder containing wind turbine, photovoltaic, microturbine and battery. Case studies demonstrated that the proposed method outperforms other operating reserve determination methods.

distribution system↗
DOE OSTI2022

Vanadium metal-organic framework for selective adsorption

A permanently porous vanadium(II)-containing metal-organic framework (MOF) with vanadium(II) centers and methods for synthesis of such MOF frameworks are provided. Methods for using such compounds to selectively react with N2 over CH4 are provided. In the synthetic methods, a vanadium source, such as VY2(tmeda)2, where Y is a halogen and tmeda is N,N,N′,N′-tetramethylethane-1,2-diamine and a H2(ligand) are reacted in the presence of acid in a solvent at between 110° C. and 130° C. to form an intermediate product. The intermediate product is collected and washed with a washing agent, such as DMF and acetonitrile, and the vanadium(II) based MOF is activated by heating the washed intermediate product to at least 160° C. under dynamic vacuum.

Long, Jeffrey R.↗
NASA NTRS2013

Aviation Safety: Modeling and Analyzing Complex Interactions between Humans and Automated Systems

The on-going transformation from the current US Air Traffic System (ATS) to the Next Generation Air Traffic System (NextGen) will force the introduction of new automated systems and most likely will cause automation to migrate from ground to air. This will yield new function allocations between humans and automation and therefore change the roles and responsibilities in the ATS. Yet, safety in NextGen is required to be at least as good as in the current system. We therefore need techniques to evaluate the safety of the interactions between humans and automation. We think that current human factor studies and simulation-based techniques will fall short in front of the ATS complexity, and that we need to add more automated techniques to simulations, such as model checking, which offers exhaustive coverage of the non-deterministic behaviors in nominal and off-nominal scenarios. In this work, we present a verification approach based both on simulations and on model checking for evaluating the roles and responsibilities of humans and automation. Models are created using Brahms (a multi-agent framework) and we show that the traditional Brahms simulations can be integrated with automated exploration techniques based on model checking, thus offering a complete exploration of the behavioral space of the scenario. Our formal analysis supports the notion of beliefs and probabilities to reason about human behavior. We demonstrate the technique with the Ueberligen accident since it exemplifies authority problems when receiving conflicting advices from human and automated systems.

Muti-agent System↗
NASA NTRSDate not supplied

Inertial Transfer: Concept and Multi-Agent Approach

Research and development of cost saving technologies is vital to the success of NASA’s strategic goal to extend human presence deeper into space and to the moon for sustainable long-term exploration and utilization. Reduction of mass has long been a method of reducing space mission costs. In this submission, Inertial Transfer, a new approach to mass transfer in space, is presented. A Multi-Agent System solution to the problem space is discussed. A scaled base-line simulator is constructed and demonstrated which will enable the development of AI capabilities necessary to perform Inertial Transfer. Finally, future work and key challenges are discussed.

Multi-Agent↗
NASA NTRS2001

Sensitivity Studies for Space-Based Global Measurements of Atmospheric Carbon Dioxide

Carbon dioxide (CO2) is well known as the primary forcing agent of global warming. Although the climate forcing due to CO2 is well known, the sources and sinks of CO2 are not well understood. Currently the lack of global atmospheric CO2 observations limits our ability to diagnose the global carbon budget (e.g., finding the so-called "missing sink") and thus limits our ability to understand past climate change and predict future climate response. Space-based techniques are being developed to make high-resolution and high-precision global column CO2 measurements. One of the proposed techniques utilizes the passive remote sensing of Earth's reflected solar radiation at the weaker vibration-rotation band of CO2 in the near infrared (approx. 1.57 micron). We use a line-by-line radiative transfer model to explore the potential of this method. Results of sensitivity studies for CO2 concentration variation and geophysical conditions (i.e., atmospheric temperature, surface reflectivity, solar zenith angle, aerosol, and cirrus cloud) will be presented. We will also present sensitivity results for an O2 A-band (approx. 0.76 micron) sensor that will be needed along with CO2 to make surface pressure and cloud height measurements.

Mao, Jian-Ping↗
DOE OSTI2022

Tangent gradient concentration material for battery, digital gradient concentration material for battery

The invention provides a cathode active material having a discrete change in concentrations of a first base region and a second pulse region. Also provided is a method for preparing a cathode active material, the method having the steps: supplying chelating agent, aqueous basic solution and a first aqueous metal salt solution to a reactor to create a base region; supplying a second aqueous metal-salt solution to a reactor to form a pulse region, wherein the second aqueous metal-salt solution is intermittently or continuously added during or after the creation of the base region; thermally treating the base region and the pulse region to create active metal precursors; mixing the precursors with lithium salt to produce a mixture; and thermally treating the mixture.

Shin, YoungHo↗
DOE OSTI2023

Effect of Dual Environment Aging on Flexible Polyurethane Based Adhesive

Abstract Environmental degradation of adhesives naturally increases with the intensity of the ambient weathering agents involved. During service life, these materials are never subjected to a constant environmental loading. Real-time applications expose the material to multiple weather conditions, ranging from dry to humid or fully wet conditions. While some understanding exists about aging environments in isolation, we intend to investigate the effect of multiple environments on the constitutive behavior of the materials in question. The extent of damage can be accessed by analyzing the changes in constitutive behavior and toughness of aged material. Therefore, this aging experiment was designed around two-way aging regimes involving combinations of thermo-oxidation, hydrolytic and hygrothermal aging environments. We selected a polyurethane based flexible adhesive which is commonly used in the automotive industry as a glass sealant. The aged specimens were subjected to uniaxial tensile tests, and variation in material toughness and constitutive behavior was analyzed to ascertain the mechanics involved in the case of each environmental exposure. We outlined how different environments affect the material in isolation and how they interact with other weathering conditions. This study will help better understand and model the damage mechanics involved in exposure to multiple environmental conditions.

Shaafaey, Mamoon↗
NASA NTRS2004

Verifying Multi-Agent Systems via Unbounded Model Checking

We present an approach to the problem of verification of epistemic properties in multi-agent systems by means of symbolic model checking. In particular, it is shown how to extend the technique of unbounded model checking from a purely temporal setting to a temporal-epistemic one. In order to achieve this, we base our discussion on interpreted systems semantics, a popular semantics used in multi-agent systems literature. We give details of the technique and show how it can be applied to the well known train, gate and controller problem. Keywords: model checking, unbounded model checking, multi-agent systems

Kacprzak, M.↗
DOE OSTI2019

A novel targeted plugging and fracture‐adaptable gel used as a diverting agent in fracturing

Abstract Diverting agents that could plug a targeted location and fill different shapes of fractures have attracted an increasing attention in the field of fracturing. In this study, a series of novel diverting agents were prepared by mixing aldehyde sodium alginate (ASA) and amino gelatin (AG) through a Schiff base reaction to form a primary network, polylactic acid (PLA) fibers were added to produce a 3D network, and Ca 2+ was mixed in as an ionic cross‐linking agent to strengthen the cross‐linking points. It was found that gelation time, swelling behavior, and mechanical performance could be controlled by varying the content of aldehyde groups and amino groups. Gelation time could be controlled in 1‐10 minutes. Plugging behavior and degradation tests demonstrated that the hydrogel could suit fractures with various shapes and plug effectively under high temperatures and pressures, and it could eventually become acidic fluid to help clean the wellbore. This novel ASA/AG/PLA hydrogel constitutes a promising environmentally friendly diverting agent in the application of diversion fracturing.

Zhang, Yuyuan↗
DOE OSTI2024

Deep Multi-Agent Reinforcement Learning for Real-World Signalized Traffic Corridor Control

Signalized traffic control problem has been addressed recently with deep Reinforcement Learning (RL) approaches involving diverse state, action, and reward structures. While significant progress has been noted in the literature, open challenges still remain in the areas of adaptive signal phase timing, coordination in a multi-intersection corridor setting, and consideration of real-world traffic conditions. In the context of deep RL-based problem framing, extensions are needed that enable adaptive signal phase timings in an intersection agent's action space, computationally efficient information sharing among neighboring signalized intersection agents along a corridor, and experimentation in realistic simulation environments. In this paper, we develop a deep Advantage Actor Critic (A2C) multi-agent RL (MARL) approach capturing the research extensions above and apply it within a real-world calibrated Aimsun Next traffic corridor simulation model based on traffic data from the City of Coral Gables, Florida. For a multi-intersection corridor control setting, our numerical simulation experiments with a decentralized A2C MARL algorithm applied at different time periods led to a total average corridor travel delay reduction (expressed in seconds/mile averaged over vehicles) from 4.9% to 19.9% compared to state-of-the-art actuated control.

Shuvo, Salman S. [BATTELLE (PACIFIC NW LAB)]↗
NASA NTRS1991

The AI Bus architecture for distributed knowledge-based systems

The AI Bus architecture is layered, distributed object oriented framework developed to support the requirements of advanced technology programs for an order of magnitude improvement in software costs. The consequent need for highly autonomous computer systems, adaptable to new technology advances over a long lifespan, led to the design of an open architecture and toolbox for building large scale, robust, production quality systems. The AI Bus accommodates a mix of knowledge based and conventional components, running on heterogeneous, distributed real world and testbed environment. The concepts and design is described of the AI Bus architecture and its current implementation status as a Unix C++ library or reusable objects. Each high level semiautonomous agent process consists of a number of knowledge sources together with interagent communication mechanisms based on shared blackboards and message passing acquaintances. Standard interfaces and protocols are followed for combining and validating subsystems. Dynamic probes or demons provide an event driven means for providing active objects with shared access to resources, and each other, while not violating their security.

Schultz, Roger D.↗