Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Mobile”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 739 records · Page 41

Gecko Mobility Aids for a Common Habitat Architecture

Spacecraft large enough for crew to move around inside them have traditionally used handrails and foot restraints to enable crew mobility. The mass of this hardware can become significant in large spacecraft such as the Common Habitat. Additionally, handrails and foot restraints in a multi-gravity habitat are trip hazards when the habitat is in a gravity environment. Further, ISS crew have noted risks of breaking ankles and wrists when using handrails for translation and have noted places where not enough handrails are present. Robotic gecko-derived grippers developed by JPL to retrieve satellites can be adapted to crew-worn pads that can adhere to surfaces to enable crew translation in microgravity. This technology will help to eliminate the need for handrails and foot restraints for mobility in crewed microgravity spacecraft cabins. It has the potential to achieve significant mass reductions in future space habitats, with application to suborbital flight, LEO, cislunar space, interplanetary space, the Moon, and Mars. Additionally, it can prevent crew injury and discomfort. Project goals and objectives are to prepare gecko uniform prototypes for use in multi-gravity testing and conduct initial investigations into human factors of postures and motions needed for intravehicular activity (IVA) translation and restraint in multiple gravity environments, without the use of handrails or foot restraints. Gecko grippers have been tested for use as robotic end effectors terrestrially, on microgravity aircraft, and aboard the ISS. Using the grippers as a body-mounted system to achieve IVA crew mobility is a new application that has not been pursued outside of this effort. This work will continue paper studies performed by NASA student interns by developing physical prototypes of spacecraft crew uniforms with gecko-derived body-mounted grippers. Clothing prototypes may include long sleeves, short sleeves, long pants, shorts, gloves, and/or booties equipped with gecko gripper pads. Forward work is to test these uniforms in a 1g environment to verify that the design does not introduce obstructions, trip hazards, or other consequences when used in terrestrial gravity. Based on the 1g test results, the uniform prototypes will be refined, and a test plan developed for testing at 0g, (1/6)g, and (3/8)g.

Restraints and Mobility Aids↗

Advancing Air Mobility: Few-Shot Learning in Airspace Research and Development

The advancement of Air Mobility, particularly in the context of Advanced Air Mobility (AAM) and Urban Air Mobility (UAM), represents a transformative shift in aviation's role in modern society. A comprehensive understanding of requirement consistency is paramount for fostering interoperability, standardization, and cost-effectiveness within airspace systems. This paper introduces a novel approach utilizing a pretrained Sentence Transformers model and few-shot learning to address this crucial aspect task of flagging potentially inconsistent requirements. Few-shot learning supports the development of this future through ensuring the accuracy and consistency of identified requirements with little human oversight. This approach offers a promising solution to the challenges of requirement consistency identification in airspace systems. By harnessing the power of advanced NLP techniques with fine-tuned models, stakeholders can enhance efficiency, accuracy, and scalability; ultimately fostering improved interoperability, standardization, and cost-effectiveness in airspace management.

Natural Language Processing↗

Physiological and Subjective Responses of Pilots During Advanced Air Mobility Flight Testing With Automated Systems

Aviation is constantly evolving, mostly due to the integration of automated systems into the National Airspace System. This presents a host of challenges and opportunities. NASA's Advanced Air Mobility (AAM) project has taken a significant leap forward with a research flight test led by the Integration of Automated Systems (IAS) sub-project. This effort focused on assessing automated flight deck algorithms essential for supporting high-density Urban Air Mobility (UAM) operations. Carrying out a two-ship flight test in UAM Maturity Level 4 scenarios, the team evaluated state-of-the-art algorithms, including Hazard Perception and Avoidance (HPA) and flight path management (FPM) systems. This presentation focuses on results of pilots' physiological and subjective responses during the flight scenarios conducted. In collaboration with Lockheed Martin Advanced Technology Laboratories (ATL), we collected and analyzed live-flight biometric data using eye tracking, mobile brain imaging, and heart rate sensors. The data provides insights into pilots' workload and cognitive engagement while navigating automated tools, leveraging both biometric data and post-encounter subjective assessments. The research highlights the interaction between human operators and automated systems, contributing valuable lessons learned about gathering human data in live-flight environments. The knowledge acquired from this endeavor enhances our understanding of human factors in automated flight and informs future studies attempting to undertake similar feats.

air mobility↗

Urban Air Mobility Traffic Analysis Tool for Airspace Involving Vertiport Hub Operations to Examine Simulated Conflicts

Presented herein are details of the development of an Urban Air Mobility Traffic Analysis Tool (UAM TAT), designed to analyze the traffic of Vertical Take-off and Landing (VTOL) air-craft in urban agglomerations to enable the Urban Air Mobility(UAM) operations. The tool aims to address challenges of UAM operations in a simulated airspace by testing different scenarios and methods for air traffic management. It emphasizes the need for effective risk management practices and methodologies to ensure the safety of operations, given the increasing use of highly automated aircraft (i.e., Advanced Air Mobility (AAM))in urban environments. The tool is modular and allows for the simulation of various families of VTOLs and different air traffic rules, making it suitable for defining and estimating airspace and vertiports capacity, determining VTOL requirements, and testing and comparing air traffic management methods. The results of five different simulations are presented that show the capabilities and functionalities of the tool. The simulations present the impact of vertiport hub operations and various ATM approach on the VTOLs’ conflicts.

Urban Air Mobility↗

Scanning Mobility Particle Sizer-Portable Optical Particle Spectrometer Intercomparison Field Campaign Report

A portable optical particle spectrometer (POPS) has recently been acquired by the United Kingdom Meteorological (UK Met) Office with the intention of mounting it on an unmanned aerial vehicle (UAV) for atmospheric aerosol research. Before conducting research with the new instrument, an intercomparison has been conducted to test the performance of the POPS against a scanning mobility particle sizer (SMPS) — a veteran and well-characterized particle sizer. As part of the Cloud-Aerosol-Radiation Interactions and Forcing (CLARIFY) campaign, the POPS was installed at the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility mobile site on Ascension Island in the South Atlantic Ocean, alongside an ARM-operated SMPS. Both instruments sampled continuously from 20 August to 9 September, 2017. The SMPS and the POPS were connected to a common aerosol inlet; however, in the case of the SMPS, the sample air was dried before it entered the instrument. The POPS is a miniaturized optical particle counter designed specifically for use in balloon and UAV applications. The instrument is fully described in Goa et al. (2016) and so is only briefly described here. The POPS samples particles by drawing air through an inlet tube into an optical chamber, where it is illuminated by a 405nm laser. A sheath air flow is used to focus the sample air into the center of the laser beam, and the sample flow is maintained at a near-constant rate by an onboard pump. Side-scattered laser light is reflected into a photomultiplier tube by a hemispherical mirror, and the signal amplitude recorded by a data logger. Individual particle sizes are then inferred by comparing the recorded signal amplitudes to scattering amplitudes calculated using Mie theory. In common with other optical particle counters, the POPS size distributions are influenced by the refractive index used in the Mie calculations. The POPS is calibrated by the manufacturers (Handix Scientific) using latex spheres, with a refractive index (RI) of 1.615+0.001i. Sampling aerosols with a different refractive index, particularly if they are strongly absorbing, will result in significant uncertainties/errors in the particle size distributions (PSDs). We have therefore used scattering amplitude curves (calculated by Handix) for more absorbing aerosols, with an RI of 1.54+0.027i, which is expected to be more representative of the biomass-burning aerosol particles sampled at the ARM site during the CLARIFY campaign. In contrast to the POPS, the SMPS measures particle size using the differential mobility technique after applying an electrical charge to aerosol particles. The method is independent of the refractive index (Ruzer 2013).

CLARIFY, portable optical particle spectrometer, s↗

Mobility Behavioral Responses to Transportation Network Companies

This research investigates how a disruptive force -- Transportation Network Companies (TNCs) -- is impacting energy consumption in transportation. It also helps better understand specific areas that encourage energy efficiency increases in mobility. It also helps to better understand specific areas that encourage energy efficiency increases in mobility. There are limited data sources and research to understand the energy implications of TNC ride-hailing services. This task is gathering data and conducting analysis related to TNCs from a variety of sources. Results will start to fill a gap in the energy implications induced by the mobility behavior responses to TNCs. Effect analysis of TNC date of entry on vehicle registrations may indicate extent to which travellers value existing vehicles, and how makeup of the on-road fleet is changing due to TNCs. Preliminary analysis of RideAustin data suggests that nearly half of all TNC miles traveled are without a rider. Results can be used as inputs to BEAM and POLARIS to forecast system energy use under different TNC scenarios.

33 ADVANCED PROPULSION SYSTEMS↗

Sustainability, Scalability and Resiliency of the Town of Innisfil Mobility-on-Demand Experiment: Preliminary Results, Analyses, and Lessons Learned: Preprint

In 2017, the Town of Innisfil, Ontario launched Innisfil Transit in partnership with Uber, a transportation network company, to provide a subsidized on-demand public mobility service as an alternative to investing in a new fixed-route bus service. The performance of Innisfil Transit is documented in a 2021 Ryerson University report which shows greater cost effectiveness of the mobility provided over the proposed bus alternative (Sweet, Mitra, and Benaroya 2021). This paper expands on those findings by assessing Innisfil Transit with respect to sustainability, scalability, and resiliency. First, we quantify the energy and emissions of this program relative to traditional transit and driving alone across varying powertrains. We then characterize a conservative first-order estimate of the percentage of US communities that fall within a similar spatial-demographic tier as Innisfil. Replicability also hinges on service cost and performance in comparison to average values for low-density transit in the US. Lastly, most transit agencies experienced a significant drop in demand (as much as 90%) with slowly rebounding ridership since the onset of the COVID-19 pandemic. The resiliency of the Innisfil program to the pressures induced by the pandemic is examined in comparison to other transit operations. The lessons learned across these three dimensions complement prior work to better understand the efficiency and sustainability of on-demand public mobility service for low-density communities like Innisfil.

ADVANCED PROPULSION SYSTEMS↗

Automated Mobility Platforms: A Framework for Versatile, Energy-Efficient Urban Transportation for the 21st Century: Preprint

This paper presents automated mobility platforms (AMPs) as a framework to deliver high-quality urban mobility. AMPs leverage advances in sensing technology developed from automated roadway vehicles to provide opportunities for efficient movement of people and goods in dense urban environments, campuses, and large facilities like airports. In this paper, we layout the concept of AMPs and how they can serve the mobility needs of the population by providing service at the intersection of micromobility (services such as electric scooters or bikes), personal rapid transit, and moving walkways. Several key attributes and justification for the AMPs concept are described, including improvements to accessibility (inherent in design) covering both socioeconomic and disability equity, safety, energy efficiency, cost-effectiveness, urban land and space management, and scalability. We summarize the results from an ongoing national laboratory-sponsored, faculty-supported, student-led investigation into AMPs that includes stakeholder engagement and technical feasibility assessment.

ADVANCED PROPULSION SYSTEMS↗

A Mobility Energy Productivity Evaluation of On-Demand Transit: A Case Study in Arlington, Texas

On-demand transit (ODT) systems are increasing in number and size. In order to evaluate and quantify outcomes, we use the Mobility Energy Productivity (MEP) metric, a holistic tool to analyze, quantify, and compare the mobility and accessibility of various transportation modes in a specific area. In this paper, we apply the MEP tool to the ODT system in Arlington, Texas, and compare the results among four existing transportation modes (drive, transportation network company, transit, and bike) and five additional ODT scenarios. We focus our analysis on the opportunities that an ODT system presents such as serving disadvantages communities. While the results in Arlington show the typical U.S. pattern of driving receiving the highest MEP score, the ODT system best serves those in disadvantaged communities, helping with an equity design goal. ODT improved the average MEP score across the service area by 100% when considering only non-private vehicle modes (bike, transit, and ODT). For the ODT scenarios, decreasing the wait time 50% compared to the baseline scenario led to a nearly 160% increase in MEP score, while increasing the ODT travel speed by 21% led to an 80% improvement in MEP score. The decreased wait time scenario had the highest MEP score out of the six ODT scenarios. This paper demonstrates how ODT can enhance mobility, particularly for disadvantaged communities. The results of a MEP analysis can be used by researchers and transit agencies to compare transportation modes and improve the effectiveness of transportation systems in subareas across a service area.

accessibility↗

A Proposed Taxonomy for Advanced Air Mobility

There has been a large growth in interest of utilizing new technologies—most notably electrified propulsion and automation—as well as new business models to bring aviation services into the daily lives of a greater segment of society. Generally, these services are envisioned to augment existing ground modes of transportation or to enable new operating capabilities for shorter-range aviation missions. These services, which have become known as advanced air mobility (AAM), include passenger transportation, cargo transportation, and aerial work missions, such as aerial photography. In this paper we describe advanced air mobility and provide a framework based on demand and supply concepts that can be used for developing a taxonomy for AAM with a focus on passenger applications. This taxonomy is intended to facilitate the nascent AAM stakeholder community in adopting a common terminology and to enable better coordination among disparate AAM research and development activities.

advanced air mobility↗

A fast integrated mobility spectrometer for rapid measurement of sub-micrometer aerosol size distribution, Part II: Experimental characterization

A Fast Integrated Mobility Spectrometer (FIMS) with a wide dynamic size range has been developed for rapid aerosol size distribution measurements. The design and model evaluation of the FIMS are presented in the preceding paper (Paper I), and this paper focuses on the experimental characterization of the FIMS. Monodisperse aerosol with diameter ranging from 8 to 600 nm was generated using Differential Mobility Analyzer (DMA), and was measured by the FIMS in parallel with a Condensation Particle Counter (CPC). The mean particle diameter measured by the FIMS is in good agreement with the DMA centroid diameter. Comparison of the particle concentrations measured by the FIMS and CPC indicates the FIMS detection efficiency is essentially 100% for particles with diameters of 8 nm or larger. For particles smaller than 20 nm or larger than 200 nm, FIMS transfer function and resolution can be well represented by the calculated ones based on simulated particle trajectories in the FIMS. For particles between 20 and 200 nm, the FIMS transfer function is boarder than the calculated, likely due to non-ideality of the electric field, including edge effects near the end of the electrode, which are not represented by the 2-D electric field used to simulate particle trajectories.

54 ENVIRONMENTAL SCIENCES↗

Synopsis of NREL's Automated Mobility District (AMD) Research Program and Associated Publications

An automated mobility district (AMD) envisions a system of integrated mobility options that serves major activity centers such as campuses, central business districts, and large medical facilities. The National Renewable Energy Laboratory (NREL) has been investigating the implementation prospects for fully automated passenger transport systems that are deployed to operate within dense urban settings. This document provides a synopsis of findings revealed over the last three phases of work, which have yielded insights into the creation and management of AMDs anticipated to use automated vehicle (AV) technology over the next decade. Phase I and Phase II tracked the deployment and lessons learned from 10 early-stage demonstrations of automated shuttle deployments, and their associated insights into the challenges for automated driving systems to achieve safe operations within district-scale deployments. Phase III began in-depth investigations of critical subsystem components, as automation, electrification, and on-demand service continue to converge within initial AMD operations. These directed studies focus on elements of electrification, curbfront/station management, the role of infrastructure sensing, and overall integration of AMD safety management in central, simultaneous coordination of multiple AMD fleets. Future research in AMDs includes systems engineering methodology (more frequently referred to as "digital twins") for planning, design, testing, and ongoing operation of AMDs; location (or co-location) of management functions; and human supervision and passenger communications for safety and security in unattended vehicles. The synopsis references the foundational research products (papers and presentations) that have been published through conference proceedings, journal articles, and NREL reports.

33 ADVANCED PROPULSION SYSTEMS↗

Envisioning Tomorrow's Sustainable Mobility Systems

In the race to achieve efficient, accessible, affordable, and decarbonized transportation, which mobility solutions and strategies will get us to the finish line? Thought leaders from government, industry, and academia convened in mid-2023 at the National Renewable Energy Laboratory (NREL) to propose answers to this question. They worked to determine the research, development, and deployment challenges and opportunities that should be prioritized to create tomorrow's sustainable mobility systems. This fact sheet outlines cross-cutting themes and key findings from the workshop.

ADVANCED PROPULSION SYSTEMS,ENERGY PLANNING, POLIC↗

Large Modulation of Charge Carrier Mobility in Doped Nanoporous Organic Transistors

Molecular doping of organic electronics has shown promise to sensitively modulate important device metrics. One critical challenge is the disruption of structure order upon doping of highly crystalline organic semiconductors, which significantly reduces the charge carrier mobility. This paper demonstrates a new method to achieve large modulation of charge carrier mobility via channel doping without disrupting the molecular ordering. Central to the method is the introduction of nanopores into the organic semiconductor thin films via a simple and robust templated meniscus-guided coating method. Using this method, the charge carrier mobility of C 8 -benzothieno[3,2-b]benzothiophene transistors is boosted by almost sevenfold. This paper further demonstrates enhanced electron transport by close to an order of magnitude in a diketopyrrolopyrrole-based donor–acceptor polymer. Combining spectroscopic measurements, density functional theory calculations, and electrical characterizations, the doping mechanism is identified as partial-charge-transfer induced trap filling. The nanopores serve to enhance the dopant/organic semiconductor charge transfer reaction by exposing the π-electrons to the pore wall.

36 MATERIALS SCIENCE↗

On the mobilization of metals by CO 2 leakage into shallow aquifers: exploring release mechanisms by modeling field and laboratory experiments

The dissolution of CO 2 in water leads to a pH decrease and a carbonate content increase in affected groundwater, which in turn can drive the mobilization of metals from sediments. The mechanisms of metal release postulated in various field and laboratory studies often differ. Drawing primarily on previously published results, we examine contrasting metal mobilization behaviors at two field tests and in one laboratory study, to investigate whether the same mechanisms could explain metal releases in these different experiments. Numerical modeling of the two field tests reveals that fast Ca-driven cation exchange (from calcite dissolution) can explain the release of most major and trace metal cations at both sites, and their parallel concentration trends. The dissolution of other minerals reacting more slowly (superimposed on cation exchange) also contributes to metal release over longer time frames, but can be masked by fast ambient groundwater velocities. Therefore, the magnitude and extent of mobilization depends not only on metal-mineral associations and sediment pH buffering characteristics, but also on groundwater flow rates, thus on the residence time of CO 2 -impacted groundwater relative to the rates of metal-release reactions. Sequential leaching laboratory tests modeled using the same metal-release concept as postulated from field experiments show that both field and laboratory data can be explained by the same processes. Finally, the reversibility of metal release upon CO 2 degassing by de-pressurization is also explored using simple geochemical models, and shows that the sequestration of metals by resorption and re-precipitation upon CO 2 exsolution is quite plausible and may warrant further attention.

54 ENVIRONMENTAL SCIENCES↗

Low‐Loss Tunable Infrared Plasmons in the High‐Mobility Perovskite (Ba,La)SnO 3

Abstract BaSnO 3 exhibits the highest carrier mobility among perovskite oxides, making it ideal for oxide electronics. Collective charge carrier oscillations known as plasmons are expected to arise in this material, thus providing a tool to control the nanoscale optical field for optoelectronics applications. Here, the existence of relatively long‐lived plasmons supported by high‐mobility charge carriers in La‐doped BaSnO 3 (BLSO) is demonstrated. By exploiting the high spatial and energy resolution of electron energy‐loss spectroscopy with a focused beam in a scanning transmission electron microscope, the dispersion, confinement ratio, and damping of infrared localized surface plasmons (LSPs) in BLSO nanoparticles are systematically investigated. It is found that LSPs in BLSO exhibit a high degree of spatial confinement compared to those sustained by noble metals and have relatively low losses and high quality factors with respect to other doped oxides. Further analysis clarifies the relation between plasmon damping and carrier mobility in BLSO. The results support the use of nanostructured degenerate semiconductors for plasmonic applications in the infrared region and establish a solid alternative to more traditional plasmonic materials.

36 MATERIALS SCIENCE↗

Resilient distributed state estimation with mobile agents: overcoming Byzantine adversaries, communication losses, and intermittent measurements

Applications in environmental monitoring, surveillance and patrolling typically require a network of mobile agents to collectively gain information regarding the state of a static or dynamical process evolving over a region. However, these networks of mobile agents also introduce various challenges, including intermittent observations of the dynamical process, loss of communication links due to mobility and packet drops, and the potential for malicious or faulty behavior by some of the agents. The main contribution of this paper is the development of resilient, fully-distributed, and provably correct state estimation algorithms that simultaneously account for each of the above considerations, and in turn, offer a general framework for reasoning about state estimation problems in dynamic, failure-prone and adversarial environments. Specifically, we develop a simple switched linear observer for dealing with the issue of time-varying measurement models, and resilient filtering techniques for dealing with worst-case adversarial behavior subject to time-varying communication patterns among the agents. Here, our approach considers both communication patterns that recur in a deterministic manner, and patterns that are induced by random packet drops. For each scenario, we identify conditions on the dynamical system, the patrols, the nominal communication network topology, and the failure models that guarantee applicability of our proposed techniques. Finally, we complement our theoretical results with detailed simulations that illustrate the efficacy of our algorithms in the presence of the technical challenges described above.

42 ENGINEERING↗

Mobilization of mercury from contaminated creekbank soils

The industrial use of mercury (Hg) led to the contamination of numerous watersheds worldwide, including the East Fork Poplar Creek (EFPC) in Tennessee, USA. Mercury can accumulate in creek banks and floodplain soils and is mobilized into downstream environments due to erosion from precipitation and flooding. Here, this study aimed to evaluate the geochemical conditions contributing to the release of Hg from contaminated soils in this watershed. Bank soil samples from the EFPC watershed with total Hg concentrations ranging from 27.2 to 1,425 mg·kg −1 were used in a series of batch experiments with artificial creek water at a solid-to-solution ratio of 1:30 to assess Hg release. Additional experiments examined Hg release across different soil size fractions and solid-to-solution ratios, as well as the effect of dissolved organic matter and time on Hg mobilization. Mercury release ranged from 0.011 to 0.17% of the total soil Hg and is correlated with total Hg concentrations. Variations in release among size fractions suggested heterogeneous distribution of labile Hg species. Results indicated two distinct solubility regimes depending on solid-to-solution ratios. Dissolved organic matter enhanced Hg release, and time-dependent experiments showed that changes in mercury speciation could decrease dissolved Hg concentrations over time. Identifying conditions that promote Hg mobilization from contaminated soils improves our understanding of Hg fluxes into downstream environments. Key factors influencing mercury release include soil characteristics, water chemistry, and temporal changes in mercury speciation.

54 ENVIRONMENTAL SCIENCES↗