Search NASA⌕ Search

SEARCH · Search NASA

Results for “mobile applications”

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 271 records · Page 15

Command and Control Concepts for an Lift Plus Cruise Electric Vertical Takeoff and Landing Vehicle

Electric Vertical Takeoff and Landing (eVTOL) vehicles have the potential to enable cost effective Urban Air Mobility (UAM) applications. Many of these vehicle concepts will takeoff vertically like a helicopter, transition to fly like an airplane, and then transition back to land vertically like a helicopter. However, these concepts may also pose several challenging handling and control problems, which must be addressed prior to safe and reliable urban operations. This study investigates some of these challenges by evaluating different command and control concepts for a conceptual Lift Plus Cruise vehicle designed by NASA’s Revolutionary Vertical Lift Technology (RVLT) project. Four different command concepts with increasing levels of automation are developed. The command and control architecture for these concepts is presented along with findings from the evaluation of these concepts in a series of three piloted studies in the Vertical Motion Simulator at NASA Ames Research Center, where pilots flew operationally relevant flight test maneuvers specifically designed to expose potential deficiencies. The higher-level control systems and the associated pilot interfaces were shown to improve performance and handling in many cases, especially for higher precision and lower to moderate aggression maneuvers. The benefits were limited for higher aggression tasks in environmentally stressing conditions, due to the slower response of the automation and inherent limitations of the vehicle design, which highlights the potential need for tradeoffs between concept of operations and vehicle capabilities

Thomas Lombaerts↗

Simplified Vehicle Control Concept for a Lift Plus Cruise eVTOL Vehicle

Electric Vertical Takeoff and Landing (eVTOL) vehicles have the potential to enable cost effective Urban Air Mobility (UAM) applications. These concepts may also pose several challenging handling and control problems, which must be addressed prior to safe and efficient urban operations. This paper investigates a simplified vehicle control concept that is designed to address some of these challenges for a conceptual Lift Plus Cruise vehicle. This concept also includes several variations of a transition-to-hover function, designed to assist pilots in capturing and maintaining a stabilized hover prior to landing. The different simplified control architectures for this concept are presented along with preliminary findings. Preliminary results show that the simplified control concept can be effective in assisting pilots to achieve safe and reliable hover landings, and that transition-to-hover functions have the potential of reducing workload while increasing accuracy. A follow on evaluation will be performed in the Vertical Motion Simulator (VMS) at NASA Ames Research Center. The planned tests will focus on more operationally representative scenarios, while building upon these operations with additional test cases exploring variations in glidepath angles and wind conditions.

simplified vehicle control↗

Rapid Laser Reactive Sintering of Garnet Li 6.1 La 3 Zr 2 Al 0.3 O 12 Solid-State Electrolyte

All solid-state lithium-ion batteries (ASSLIBs) have gained significant interest in recent years due to their wide range of applications, including mobile devices, electric vehicles, and grid storage. Garnet-type Li 7 La 3 Zr 2 O 12 (LLZO) solid-state electrolyte (SSE) continues to be a significant player in the fabrication of ASSLIBs with excellent ionic conductivity on the order of 10 -3 S•cm -1 with the integration of dopants and sintering aids to assist conductivity and structural evolution during the sintering procedure. Traditional sintering techniques, such as solid-state sintering (SSS), have been proven to yield desirable crystal structures. However, the low ionic conductivity results from inferior microstructure, and lithium loss is a significant challenge. Recently, a relatively novel sintering process called rapid laser reactive sintering (RLRS) has shown great potential for achieving fully dense solid oxide electrolytes with less surface element loss, resulted in high ionic conductivity. Here, we applied the same RLRS method to fabricate LLZO dense electrolyte with different amounts of aluminum dopants. We hope the rapid high-temperature sintering can densify the electrolyte and avoid the lithium loss for achieving high lithium-ion conductivity. In this work, we optimized multiple combinations of laser parameters (speed, power, and defocus distance), initial precursor composition, and controlled atmospheres to discover the optimal conditions for reaching the efficacious crystal structure, microstructure, and ionic conductivity.

25 ENERGY STORAGE↗

Development of Shielding Benchmarks Using the Godiva IV Assembly

The Nuclear Criticality Safety Program (NCSP) is developing a shielding benchmark using the Godiva IV assembly as a source. Its present status is reviewed herein. Even eight decades into the nuclear era, substantial work remains to develop a database of shielding benchmarks to support future nuclear development. A nuclear simulation is only as good as its supporting data, inputs, and validation basis. Uncertainty in these areas is addressed using conservatism, which adds margin and, occasionally, cost. In many shielding situations, high accuracy is not necessary because additional material is not particularly expensive. After all, 1–2 cm of lead often reduces the gamma ray dose substantially. However, in certain areas, conservatism can add unnecessary cost. These areas include mobile shielding applications such as casks, ships, microreactors, and spacecraft, where weight and, thus, margin is expensive. Although these characteristics are side benefits for NCSP shielding benchmark development, the main driver is enabling more reliable placement of criticality accident alarm systems (CAASs) in nuclear material facilities, such as those dedicated to the production of advanced reactor fuels. CAAS placement relies on more than accurate data and code validation. It also relies on sufficiently accurate materials specifications, geometry specifications, and a well-defined, alarm-producing baseline accident. All these things require tacit knowledge and understanding of the problem being evaluated. Benchmarks can help ensure this understanding.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Design Studies on Mechanically Geared, Magnetically Geared, and Direct Drive Drivetrains for UAM Applications

Urban air mobility vehicles require high reliability and high performance electric motor drive trains. In this paper, a design optimization study is carried out to compare mechanically geared, magnetically geared, and direct drive motor drivetrain topology achievable performance in a 100 kW hover power quad rotor propulsor application. Design studies are carried out accounting for a nominal mission profile. Studies are carried out assuming constant propulsor rotor RPMs of 400, 1000, 2000, and 3000 RPM. Results show that mechanically geared drives are the lightest at all RPMs but their weight benefit over direct drive and magnetically geared decays with increased rotor RPM. Direct drive is shown to always achieve the highest efficiency due to its lower motor speed resulting in low electrical frequencies. Magnetically geared drivetrains are shown to need some requirement refinement or technology improvement to provide significant benefit over direct drive drivetrains.

Thomas Tallerico↗

Design Studies on Mechanically Geared, Magnetically Geared, and Direct Drive Drivetrains for UAM Applications

Urban air mobility vehicles require high reliability and high performance electric motor drive trains. In this paper, a design optimization study is carried out to compare mechanically geared, magnetically geared, and direct drive motor drivetrain topology achievable performance in a 100 kW hover power quad rotor propulsor application. Design studies are carried out accounting for a nominal mission profile. Studies are carried out assuming constant propulsor rotor RPMs of 400, 1000, 2000, and 3000 RPM. Results show that mechanically geared drives are the lightest at all RPMs but their weight benefit over direct drive and magnetically geared decays with increased rotor RPM. Direct drive is shown to always achieve the highest efficiency due to its lower motor speed resulting in low electrical frequencies. Magnetically geared drivetrains are shown to need some requirement refinement or technology improvement to provide significant benefit over direct drive drivetrains.

Thomas Tallerico↗

Aeronautical mobile satellite service: Air traffic control applications

Canada's history both in aviation and in satellite communications development spans several decades. The introduction of aeronautical mobile satellite communications will serve our requirements for airspace management in areas not served by line-of-sight radio and radar facilities. The ensuing improvements in air safety and operating efficiency are eagerly awaited by the aviation community.

Sim, Dave↗

Mobile satellite service communications tests using a NASA satellite

Emerging applications of commercial mobile satellite communications include satellite delivery of compact disc (CD) quality radio to car drivers who can select their favorite programming as they drive any distance; transmission of current air traffic data to aircraft; and handheld communication of data and images from any remote corner of the world. Experiments with the enabling technologies and tests and demonstrations of these concepts are being conducted before the first satellite is launched by utilizing an existing NASA spacecraft.

Chambers, Katherine H.↗

A Unified Approach to Motion Control of Motion Robots

This paper presents a simple on-line approach for motion control of mobile robots made up of a manipulator arm mounted on a mobile base. The proposed approach is equally applicable to nonholonomic mobile robots, such as rover-mounted manipulators and to holonomic mobile robots such as tracked robots or compound manipulators. The computational efficiency of the proposed control scheme makes it particularly suitable for real-time implementation.

motion control↗

Microsystems, Space Qualified Electronics and Mobile Sensor Platforms for Harsh Environment Applications and Planetary Exploration

NASA Glenn Research Center is presently developing and applying a range of sensor and electronic technologies that can enable future planetary missions. These include space qualified instruments and electronics, high temperature sensors for Venus missions, mobile sensor platforms, and Microsystems for detection of a range of chemical species and particulates. A discussion of each technology area and its level of maturity is given. It is concluded that there is a strong need for low power devices which can be mobile and provide substantial characterization of the planetary environment where and when needed. While a given mission will require tailoring of the technology for the application, basic tools which can enable new planetary missions are being developed.

Hunter, Gary W.↗

Design and performance of mobile terminal for North American MSAT network

The mobile terminal (MT), which can be selected for various applications, i.e. land mobile, transportable, fixed site, and maritime use, has been developed. Medium gain and high gain antennas are available. The MT can support circuit switched voice and data service. Additionally, cellular roaming service, net radio, and Group 3 facsimile services are optionally provided. A Mitsubishi handheld portable phone can be used as a stand-alone portable cellular-only phone or it can provide MSAT voice service when connected to MT. The MT which operates in L-band (1.5 GHz/1.6 GHz) satisfies equivalent isotropically radiated power (EIRP) of 12.5 dBW minimum and G/T of -16 dB/K minimum for medium gain system and -12 dB/K for high gain system. The excellent performance of transmit phase noise and bit error rate is achieved by using new technologies.

Fuji, Tsuyoshi↗

Proof Compression and the Mobius PCC Architecture for Embedded Devices

The EU Mobius project has been concerned with the security of Java applications, and of mobile devices such as smart phones that execute such applications. In this talk, I'll give a brief overview of the results obtained on on-device checking of various security-related program properties. I'll then describe in more detail how the concept of certified abstract interpretation and abstraction-carrying code can be applied to polyhedral-based analysis of Java byte code in order to verify properties pertaining to the usage of resources of a down-loaded application. Particular emphasis has been on finding ways of reducing the size of the certificates that accompany a piece of code.

Jensen, Thomas↗

Creating a Prototype Web Application for Spacecraft Real-Time Data Visualization on Mobile Devices

Mobile devices (smart phones, tablets) have become commonplace among almost all sectors of the workforce, especially in the technical and scientific communities. These devices provide individuals the ability to be constantly connected to any area of interest they may have, whenever and wherever they are located. The Huntsville Operations Support Center (HOSC) is attempting to take advantage of this constant connectivity to extend the data visualization component of the Payload Operations and Integration Center (POIC) to a person's mobile device. POIC users currently have a rather unique capability to create custom user interfaces in order to view International Space Station (ISS) payload health and status telemetry. These displays are used at various console positions within the POIC. The Software Engineering team has created a Mobile Display capability that will allow authenticated users to view the same displays created for the console positions on the mobile device of their choice. Utilizing modern technologies including ASP.net, JavaScript, and HTML5, we have created a web application that renders the user's displays in any modern desktop or mobile web browser, regardless of the operating system on the device. Additionally, the application is device aware which enables it to render its configuration and selection menus with themes that correspond to the particular device. The Mobile Display application uses a communication mechanism known as signalR to push updates to the web client. This communication mechanism automatically detects the best communication protocol between the client and server and also manages disconnections and reconnections of the client to the server. One benefit of this application is that the user can monitor important telemetry even while away from their console position. If expanded to the scientific community, this application would allow a scientist to view a snapshot of the state of their particular experiment at any time or place. Because the web application renders the displays that can currently be created with the POIC ground system, the user can tailor their displays for a particular device using tools that they are already trained to use.

Lang, Jeremy S.↗

A Multi-Region SEIR Model Incorporating Inter-County Mobility and Time-Dependent Transmission Dynamics: Application to COVID-19 Disease Outbreak Data in North Carolina.

Classical infectious disease compartmental models typically do not incorporate spatial heterogeneity or mobility. We develop a multi-region susceptible-exposed-infected-recovered (SEIR) model in which disease dynamics are coupled via inter-region mobility and the transmission rate is both region and time dependent. We calibrate the model using rolling averages of daily COVID-19 data in all 100 North Carolina counties. Mobility parameters are prescribed using daily inter-county commuter data. The number of transmission rate parameters is substantially reduced by hypothesizing that the dynamics correlate with county-level population density. Parameter estimation is carried out using several objective functions with error terms at different scales. An additive combination of least squares error at the county-level and the state-level, along with a quadratic transmission rate polynomial, yields the lowest overall error at both spatial scales. The calibrated model is used to simulate regional effects of perturbing disease transmission rates in adjacent counties and to illustrate effects of the state’s mobility infrastructure on disease dynamics and spread for a new disease outbreak.

COVID-19 modeling↗

4800 B/S speech compression techniques for mobile satellite systems

This paper will discuss three 4800 bps digital speech compression techniques currently being investigated for application in the mobile satellite service. These three techniques, vector adaptive predictive coding, vector excitation coding, and the self excited vocoder, are the most promising among a number of techniques being developed to possibly provide near-toll-quality speech compression while still keeping the bit-rate low enough for a power and bandwidth limited satellite service.

Townes, S. A.↗

Propagation-related AMT design aspects and supporting experiments

The ACTS Mobile Terminal (AMT) is presently being developed with the goal of significantly extending commercial satellite applications and their user base. A thorough knowledge of the Ka-band channel characteristics is essential to the proper design of a commercially viable system that efficiently utilizes the valuable resources. To date, only limited tests have been performed to characterize the Ka-band channel, and they have focused on the needs of fixed terminals. As part of the value of the AMT as a Ka-band test bed is its function as a vehicle through which tests specifically applicable to the mobile satellite communications can be performed. The exact propagation environment with the proper set of elevation angles, vehicle antenna gains and patterns, roadside shadowing, rain, and Doppler is encountered. The ability to measure all of the above, as well as correlate their effects with observed communication system performance, creates an invaluable opportunity to understand in depth Ka-band's potential in supporting mobile and personal communications. This paper discusses the propagation information required for system design, the setup with ACTS that will enable obtaining this information, and finally the types of experiments to be performed and data to be gathered by the AMT to meet this objective.

Dessouky, Khaled↗

Modems for emerging digital cellular-mobile radio system

Digital modem techniques for emerging digital cellular telecommunications-mobile radio system applications are described and analyzed. In particular, theoretical performance, experimental results, principles of operation, and various architectures of pi/4-QPSK (pi/4-shifted coherent or differential QPSK) modems for second-generation US digital cellular radio system applications are presented. The spectral/power efficiency and performance of the pi/4-QPSK modems (American and Japanese digital cellular emerging standards) are studied and briefly compared to GMSK (Gaussian minimum-shift keying) modems (proposed for European DECT and GSM cellular standards). Improved filtering strategies and digital pilot-aided (digital channel sounding) techniques are also considered for pi/4-QPSK and other digital modems. These techniques could significantly improve the performance of digital cellular and other digital land mobile and satellite mobile radio systems. More spectrally efficient modem trends for future cellular/mobile (land mobile) and satellite communication systems applications are also highlighted.

Feher, Kamilo↗

Motion Trajectories for Wide-area Surveying with a Rover-based Distributed Spectrometer

A mobile ground survey application that employs remote sensing as a primary means of area coverage is highlighted. It is distinguished from mobile robotic area coverage problems that employ contact or proximity-based sensing. The focus is on a specific concept for performing mobile surveys in search of biogenic gases on planetary surfaces using a distributed spectrometer -- a rover-based instrument designed for wide measurement coverage of promising search areas. Navigation algorithms for executing circular and spiral survey trajectories are presented for widearea distributed spectroscopy and evaluated based on area covered and distance traveled.

mobile robots↗