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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Measuring Fundamental Improvements in Sustainable Urban Mobility: The Mobility-Energy Productivity Metric: Preprint

Recent technological advancements in mobility are creating many options for connecting citizens with employment, goods, and services, particularly in urban areas where modes such as bike and car shares, electric scooters, ridesourcing, and ridesharing are proliferating at a rapid pace. Analysis and tools for overall transportation planning are dominated by urban regional travel demand models whose roots in highway operations poorly reflect the system dynamics in denser areas where parking costs, convenience, and availability - not to mention sustainability concerns and quality of life - are driving people to an ever-greater spectrum of mobility services. In this paper, we present a new paradigm for evaluating mobility options within an urban area. First developed for the U.S. Department of Energy's Energy Efficient Mobility System research program, this metric is termed the Mobility-Energy Productivity (MEP) metric. At its heart, the MEP metric measures accessibility and appropriately weights it with travel time, cost, and energy of modes that provide access to opportunities in any given location. The proposed metric is versatile in that it can be computed from readily available data sources or derived from outputs of regional travel demand models. End times associated with parking, curb access, cost, and reliability and frequency of service need to be carefully considered to obtain an appropriate and accurate perspective when computing the metric. Ultimately, the MEP metric can be used to reflect the impacts of new mobility technologies (transportation network companies, electric scooters), business models (car shares and bike shares), and land-use practices (such as transit-oriented development) on sustainable urban mobility. This paper lays out the need, requirements, and framework for this new metric, and offers it, in collaboration with the American Society for Civil Engineers (ASCE), as a foundational metric for Smart City assessment.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2019

Full in silico DFT characterization of lanthanum and yttrium based oxynitride semiconductors for solar fuels

Finding new solar-energy absorber materials is one of the most significant challenges in artificial photosynthesis. Starting from the experimentally available LaTaON 2 and LaTiO 2 N oxynitrides, we use DFT to propose new sunlight absorbing semiconductors. The synthetically unknown YTaON 2 and YTiO 2 N are semiconductors with indirect band gaps of 2.7 eV and 2.9 eV, respectively. For the first time, we compute within Boltzmann transport theory the DOS-averaged effective mass and mobility of LaTaON 2 , LaTiO 2 N, YTaON 2 and YTiO 2 N. Our first principles calculations indicate that the Y-based materials possess advantageous dielectric (ε r ≥ 47), optical (α ≥ 10 4 cm –1 near band edge), and charge transport properties (m e,h*DOS ≈ 0.2; μ e,h ≈ 10 2 cm 2 V –1 s –1 ) for the conversion of solar energy into storable fuels. Furthermore, our work leads to the complete in silico design of semiconductors for water splitting.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

The Next Stage for Smart Cities: Metrics to Spur an Evolution from Technology for Efficiency to Technology for People's Needs

The Smart Cities movement is about a decade old, energized by the USDOT Smart Cities grant that sparked cities to dream big. Now, 10 years later, and multitudes of conferences and papers later, the biggest question regarding Smart Cities is whether any progress has been made? Smart Cities forums are typically led by the technology sector, either telecommunications, internet access, or most recently artificial intelligence (AI) concerns. Each of these areas have grown and found new applications in the context of Smart Cities, however, these technology applications are just tools toward ends. Do digital communications and assistance enable or foster improved access to real, tactile, non-virtual goods and services such as transportation, food, housing, trash removal, health care, education, social interaction? These and other topics are not 'big tech', but are each critical to quality of life outcomes and are day-to-day necessities, comprising many of the touch points through which citizens interact with municipal agencies. Regarding Smart Cities, relationships have not been fully refined as to how best to merge the emerging generation of technology and related trends with more mundane but essential requirements of tactile services. How should municipal managers and operators bring the range of new technology tools (e.g. on-demand transit, automated vehicles, digital connectivity) to bear to improve functions serving real- physical- non-virtual needs? How do we make cities more efficient in providing access to services and opportunities for improved quality of life? This paper examines the current Smart City movement, emerging trends, and the need to put metrics with respect to the delivery, access, and provision of real-life needs. Using a few case studies of past, present, and projected future scenarios, this paper attempts to bring Smart Cities into the real cities domain, perhaps pushing the moniker away from 'Smart' to 'Efficient' - something that can be measured, counted, and assessed. Through the consideration of the next stage of the evolution of cities from 'Smart' to 'Efficient', the combined efforts and experience of multiple researchers at the NREL and their network of collaborators highlights the need for updates metrics that can be used to start guiding efforts toward productive initiatives to improve quality of life.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
NASA NTRS2001

Electroactive polymers as artificial muscles - reality and challenges

For many years, electroactive polymers (EAP) received reIatively little attention due to the small number of available materials and their limited actuation capability. The recent emergence of EAP materials with large displacement response changed the potential capability and paradigms of these materials. The main attractive characteristic of EAP is their operational similarity to biological muscles, particularly their resilience and ability to induce large actuation strains. Even though the actuation force of existing EAP materials and their robustness require further improvement, there has already been a series of reported successes. The successful applications that were demonstrated include catheter steering element, miniature manipulator, dust-wiper, miniature robotic arm, and grippers. Some of the currently considered applications may be difficult to accomplish and it is important to scope the requirements to the level that current materials can address. Using EAP to replace existing actuators may be a difficult challenge and therefore it is highly desirable to identify a niche application where it would not need to compete with existing capabilities. The application of these materials as actuators to drive various manipulation, mobility and robotic devices involves multidiscipline including materials, chemistry, electro-mechanics, computers, electronics, etc. This paper reviews the current efforts and the expectations for the future.

Bar-Cohen, Yoseph↗
DOE OSTI2024

Resolving local ordering and structure in Mn x Ge 1- x Te alloys through thermodynamic ensembles of pair distribution functions

Characterizing local bonding environments in complex materials is essential for understanding and optimizing their properties. Equally as important is the ability to predict local motifs as a function of synthesis conditions, enhancing chemists’ ability to design properties into materials. In this study, we present an approach to leverage statistical mechanics to generate temperature- and energy-informed ensemble averaged pair distribution functions (PDFs). This method, which we have named Thermodynamic Ensemble Averages of PDFs for Ordering and Transformations (TEAPOT), utilizes density functional theory (DFT) to relax supercells while incorporating energetic penalties for local order, enabling accurate and computationally efficient analysis of local structure. We apply this method to the neutron PDF measurements of the pseudobinary MnTe–GeTe (MGT) alloy, demonstrating its capability to resolve complex local distortions and chemical ordering. Our results reveal detailed insights into phase transformations and local distortions driven by Mn substitution. For compositions that globally present as rock salt, our analysis reveals that Ge coordination geometry is heavily impacted by synthesis temperature. We propose that high temperature synthesis conditions promote a lowered Ge polyhedra distortion, promoting high charge carrier mobility due to the alignment of local and global structure. Incorporating statistical mechanics and computation into experimental analysis thus guides synthesis of tailored local structure.

36 MATERIALS SCIENCE↗
NASA NTRS1994

Photogrammetric mobile satellite service prediction

Photographic images of the sky were taken with a camera through a fisheye lens with a 180 deg field-of-view. The images of rural, suburban, and urban scenes were analyzed on a computer to derive quantitative information about the elevation angles at which the sky becomes visible. Such knowledge is needed by designers of mobile and personal satellite communications systems and is desired by customers of these systems. The 90th percentile elevation angle of the skyline was found to be 10 deg, 17 deg, and 51 deg in the three environments. At 8 deg, 75 percent, 75 percent, and 35 percent of the sky was visible, respectively. The elevation autocorrelation fell to zero with a 72 deg lag in the rural and urban environment and a 40 deg lag in the suburb. Mean estimation errors are below 4 deg.

Akturan, Riza↗
NASA NTRS2021

Atoms to Aircraft to Spacecraft

The next generation of aerospace systems requires materials and structures that combine high performance at high utilization in short missions with the possibility of high rate production, without excessive non-recurring cost, to allow for rate flexibility and shorter structural life cycles. The development of materials and structures that offer this flexibility in rate without negatively influencing performance and economic viability will require a matching and overlapping experimental and computational design approach. The objective is to go from Atom to Airframe to Spaceframe for thermoplastic unidirectional tape based fastener-free assemblies. Thermoplastic composites are chosen as the focus because these materials allow for reversible fusion bonding in every stage of their life cycle after synthesis. Our strategy is to combine multi-scale computational approaches with multi-scale experimental activities to develop an understanding of and capabilities to manufacture custom unidirectional thermoplastic tape. This tape will be the basis for our high-rate multiple-technology manufacturing approach validated by the production of two representative demonstrators for urban air mobility vehicle structures. The multi-disciplinary team will work in an integrated manner to effectively combine computational approaches with experimental approaches at each stage of characteristic manufacturing flows. The team aims for tools and technology to quantify the thermo-rheological aspects of unidirectional tape-based production and assembly of aerospace quality thermoplastic components as well as for validated tools for unidirectional tape-based thermoplastic preform and part design and manufacture. The work will be used to design and build two demonstration structural parts characteristic for urban air mobility vehicles.

Paul Ziehl↗
DOE OSTI2019

Evaluating Time Varying Connectivities and System Throughput in Opportunistic Networks for Smart Grid Applications

With increasing proliferation of smart phones, there is an opportunity to employ mobile ad hoc networks to connect to distributed energy assets located in remote areas. With embedded intelligence and edge computing capabilities, autonomous ‘edge control nodes’ can enable a decentralized energy nexus, without the need for on-demand communications. Authors have developed an opportunistic networking framework using Bluetooth Low Energy and a specialized mobile phone application that enables delay tolerant networking for the above framework. Here, this paper presents the analysis of time varying graph connectivity for such an opportunistic mobile ad hoc network. Dependence of connectivity on different network parameters such as radio characteristics, the mobility of data mules and parameters governing how connections are established are explored. Simulation results showing the variation of above trends have been presented.

Bluetooth↗
DOE OSTI2024

Seasonal Patterns in Mobile Colistin Resistance Gene Variants in Wastewater Bioaerosols and Liquid Sludge

To address the growing threat of global antimicrobial resistance, a one-health approach is needed to understand the complex socioecological cycling of antibiotic resistance genes. In this study, a metagenomics approach using DNA shotgun sequencing, metagenome assembly, and antibiotic resistance gene (ARG) annotation was used to examine seasonal patterns in the abundance of mobile colistin resistance (mcr) gene variants in bioaerosols and liquid sludge in three wastewater treatment plants (WWTPs). ARGs represented 0.2–0.8 and 0.1–0.2% of the bioaerosol and liquid sludge metagenomes, respectively, while mcr genes represented 0–0.3 and 0–0.5% of the identified ARGs in bioaerosol and liquid sludge metagenomes. Seven of the ten known mcr variants were detected in wastewater bioaerosol and liquid samples, with mcr-5 and mcr-8 being the most prevalent across all seasons and sites. Furthermore, additional functional and taxonomic annotation of mcr-containing metagenomic contigs showed that mcr genes were often located on contigs with other co-occurring ARGs and mobile genetic elements and may be harbored by opportunistic human pathogens and other bacterial taxa not previously associated with mcr genes. Atmospheric dispersion modeling showed that mcr-containing bioaerosols can be transported kilometers away from the WWTPs, resulting in the possible dissemination of these ARGs into surrounding environments and communities.

Antimicrobial agents↗
NASA NTRS1992

Crustal dynamics project data analysis, 1991: VLBI geodetic results, 1979 - 1990

The Goddard VLBI group reports the results of analyzing 1412 Mark II data sets acquired from fixed and mobile observing sites through the end of 1990 and available to the Crustal Dynamics Project. Three large solutions were used to obtain Earth rotation parameters, nutation offsets, global source positions, site velocities, and baseline evolution. Site positions are tabulated on a yearly basis from 1979 through 1992. Site velocities are presented in both geocentric Cartesian coordinates and topocentric coordinates. Baseline evolution is plotted for 175 baselines. Rates are computed for earth rotation and nutation parameters. Included are 104 sources, 88 fixed stations and mobile sites, and 688 baselines.

Ma, C.↗
NASA NTRS2011

FPGA Implementation of Stereo Disparity with High Throughput for Mobility Applications

High speed stereo vision can allow unmanned robotic systems to navigate safely in unstructured terrain, but the computational cost can exceed the capacity of typical embedded CPUs. In this paper, we describe an end-to-end stereo computation co-processing system optimized for fast throughput that has been implemented on a single Virtex 4 LX160 FPGA. This system is capable of operating on images from a 1024 x 768 3CCD (true RGB) camera pair at 15 Hz. Data enters the FPGA directly from the cameras via Camera Link and is rectified, pre-filtered and converted into a disparity image all within the FPGA, incurring no CPU load. Once complete, a rectified image and the final disparity image are read out over the PCI bus, for a bandwidth cost of 68 MB/sec. Within the FPGA there are 4 distinct algorithms: Camera Link capture, Bilinear rectification, Bilateral subtraction pre-filtering and the Sum of Absolute Difference (SAD) disparity. Each module will be described in brief along with the data flow and control logic for the system. The system has been successfully fielded upon the Carnegie Mellon University's National Robotics Engineering Center (NREC) Crusher system during extensive field trials in 2007 and 2008 and is being implemented for other surface mobility systems at JPL.

Random access memory↗
NASA NTRSDate not supplied

Refined Analysis of CO2 Emissions in Urban Air Mobility Networks

In this study, we examine the environmental impact of Urban Air Mobility (UAM) operations as measured via carbon dioxide (CO2) emissions by leveraging a computational model from previous studies that has been refined and expanded. Several scenarios are examined in which total transportation emissions for a representative day in a metro area are distributed differently among vehicle types and transportation modes. Specifically, we investigate the use of electric air vehicles in a UAM network; the increasing presence of electric ground vehicles for ground transportation; the impacts from implementing ridesharing in the UAM mode; and the effects of varying the electricity grid emissions. Results for a case study in the Chicago, IL metro area indicate that incorporating electric ground vehicles and UAM ridesharing can both lead to reduced CO2 emissions. These preliminary results indicate that carbon emissions from a UAM system leveraging ridesharing and all-electric aircraft may not be a practical operational limit on UAM, though further improvements to the modeling are warranted.

advanced air mobility↗
NASA NTRSDate not supplied

Refined Analysis of CO2 Emissions in Urban Air Mobility Networks

In this study, we examine the environmental impact of Urban Air Mobility (UAM) operations as measured via carbon dioxide (CO2) emissions by leveraging a computational model from previous studies that has been refined and expanded. Several scenarios are examined in which total transportation emissions for a representative day in a metro area are distributed differently among vehicle types and transportation modes. Specifically, we investigate the use of electric air vehicles in a UAM network; the increasing presence of electric ground vehicles for ground transportation; the impacts from implementing ridesharing in the UAM mode; and the effects of varying the electricity grid emissions. Results for a case study in the Chicago, IL metro area indicate that incorporating electric ground vehicles and UAM ridesharing can both lead to reduced CO2 emissions. These preliminary results indicate that carbon emissions from a UAM system leveraging ridesharing and all-electric aircraft may not be a practical operational limit on UAM, though further improvements to the modeling are warranted.

advanced air mobility↗
DOE OSTI2021

The Role of Mobility Data Hubs in an Integrated Decarbonized Transportation Future

The landscape for connected mobility ecosystems is evolving rapidly as information and communication technologies lower the cost and complexity of connecting people to places, integrating transportation modes and collecting data regarding such movements. These developments have been key to unlocking new business opportunities, particularly through mobility services. While the mechanisms for data collection, processing, and transfer have made significant advances in the past decade, the broader landscape of mobility data architectures and data users remains largely unresolved. It is unclear as to whether the result will converge towards a framework that resembles a coherent quilt or a disjointed patchwork of competing visions. Initial approaches to mobility data collection and provisioning have been largely siloed - by mode or software - or held for exclusive use, however several key players are quickly realizing the need and opportunities enabled through integrated mobility data eco-systems, or mobility data hubs as referred to in this paper. As the business case for hosting mobility data hubs evolves, there is great uncertainty regarding their impact to either advance or exacerbate sustainable mobility (e.g., seamless connectivity across modes, decreased energy consumption and greenhouse gas emissions, etc.). Groups such as the United Nations and World Bank have identified data platforms as a key enabler of realizing environmental and social benefits. If designed with decarbonization in mind, we hypothesize that enhanced observability provided by these ever-expanding mobility data hubs can facilitate energy and emissions reductions that are otherwise limited by transactional barriers and knowledge asymmetry that is inherent to a more siloed approach. In this sense, integration of mobility data can help to create a competitive playing field where value is not determined by exclusivity of data, but rather the quality and uniqueness of a given service. The goals of this paper are to 1) identify key players and data architectures that are emerging in a service-based mobility market, 2) explore several use cases where mobility data hubs have enabled greater sustainability outcomes, and 3) discuss key issues that will need to be resolved to fully leverage emerging mobility data hubs towards a sustainable transportation future.

ADVANCED PROPULSION SYSTEMS,MATHEMATICS AND COMPUT↗
DOE OSTI2019

Computational Studies of Photocatalysis with Metal–Organic Frameworks

Metal–organic frameworks (MOFs) as photocatalysts and photocatalyst supports combine several advantages of homogeneous and heterogeneous catalyses, including stability, post-reaction separation, catalyst reusability, and tunability, and they have been intensively studied for photocatalytic applications. There are several reviews that focus mainly or even entirely on experimental work. The present review is intended to complement those reviews by focusing on computational work that can provide a further understanding of the photocatalytic properties of MOF photocatalysts. We first present a summary of computational methods, including density functional theory, combined quantum mechanical and molecular mechanical methods, and force fields for MOFs. Then, computational investigations on MOF-based photocatalysis are briefly discussed. The discussions focus on the electronic structure, photoexcitation, charge mobility, and photoredox catalysis of MOFs, especially the widely studied UiO-66-based MOFs.

36 MATERIALS SCIENCE↗
NASA NTRS2018

Dynamic Adjustment of Simulation Parameters for Efficient Vehicle Prognostics

Model-based diagnostics and prognostics rely on state estimation and uncertainty management algorithms to produce useful information for system operators and maintainers. This information enables more informed operational decisions, condition-based maintenance, and overall mission safety assurance. Typically, uncertainty is associated with vehicle state-of-health estimation and prediction results because of modeling errors, internal or external sources of noise, and sensor inaccuracy. Probabilistic uncertainty management methods including Sequential Monte Carlo simulation are commonly used to reason about state-of-health estimates and predictions in the presence of these sources of uncertainty. However, such algorithms can be computationally expensive as they require a very large number of samples to obtain a sufficiently accurate quantification of the end of life probability distribution. As a result, highly mobile autonomous systems that leverage the prognostic results for mission-level replanning are often constrained in their processing capability because of these computationally expensive simulation approaches. Therefore, in this paper, we investigate algorithmic methods for dynamically adjusting simulation time step as well as number of samples to achieve highly efficient prognostic results while maintaining results accuracy. Results obtained from simulated flight experiments of an electric unmanned aerial vehicle are presented to verify the efficacy of such algorithms.

Prognostics↗
NASA NTRS2022

Planning for a Martian Road Trip – The Mars2020 Mobility Systems Design

The Perseverance rover landed in Jezero Crateron Mars on February 18, 2021, marking the beginning of anepic road trip across Mars. The guiding principle of thePerseverance rover design was to replicate Curiosity, exceptfor when the new mission objectives mandated a change.The scientific objectives require that Perseverance drivemore quickly and more efficiently through more complexterrain than its predecessors. The mobility system forPerseverance exemplifies this, in that key portions areidentical, yet others have had major upgrades. Key upgradesinclude more tractive and more robust tires, newengineering cameras, a new computer dedicated for imageprocessing, and a more efficient AutoNav software suite.This paper will follow how the scientific objectives led tothe key and driving mobility requirements and how theserequirements were decomposed at the different subsystems.

Stragier, Michael M.↗