SEARCH · Engineering Papers

Results for “path integrals”

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.

SourceResearch connectionFrom yearThrough year

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

At least 1,009 records · Page 56

All sources NASA NTRS DOE OSTI

NASA NTRS1987

Design and analysis of advanced flight planning concepts

The objectives of this continuing effort are to develop and evaluate new algorithms and advanced concepts for flight management and flight planning. This includes the minimization of fuel or direct operating costs, the integration of the airborne flight management and ground-based flight planning processes, and the enhancement of future traffic management systems design. Flight management (FMS) concepts are for on-board profile computation and steering of transport aircraft in the vertical plane between a city pair and along a given horizontal path. Flight planning (FPS) concepts are for the pre-flight ground based computation of the three-dimensional reference trajectory that connects the city pair and specifies the horizontal path, fuel load, and weather profiles for initializing the FMS. As part of these objectives, a new computer program called EFPLAN has been developed and utilized to study advanced flight planning concepts. EFPLAN represents an experimental version of an FPS. It has been developed to generate reference flight plans compatible as input to an FMS and to provide various options for flight planning research. This report describes EFPLAN and the associated research conducted in its development.

Sorensen, John A.↗

NASA NTRS1989

Characterization of quantum well structures using a photocathode electron microscope

Present day integrated circuits pose a challenge to conventional electronic and mechanical test methods. Feature sizes in the submicron and nanometric regime require radical approaches in order to facilitate electrical contact to circuits and devices being tested. In addition, microwave operating frequencies require careful attention to distributed effects when considering the electrical signal paths within and external to the device under test. An alternative testing approach which combines the best of electrical and optical time domain testing is presented, namely photocathode electron microscope quantitative voltage contrast (PEMQVC).

Spencer, Michael G.↗

NASA NTRS1992

Alternative methods to model frictional contact surfaces using NASTRAN

Elongated (slotted) holes have been used extensively for the integration of equipment into Spacelab racks. In the past, this type of interface has been modeled assuming that there is not slippage between contact surfaces, or that there is no load transfer in the direction of the slot. Since the contact surfaces are bolted together, the contact friction provides a load path determined by the normal applied force (bolt preload) and the coefficient of friction. Three alternate methods that utilize spring elements, externally applied couples, and stress dependent elements are examined to model the contacted surfaces. Results of these methods are compared with results obtained from methods that use GAP elements and rigid elements.

Hoang, Joseph↗

NASA NTRS1999

Quantitative Interferometry in the Severe Acoustic Environment of Resonant Supersonic Jets

Understanding fundamental fluidic dynamic and acoustic processes in high-speed jets requires quantitative velocity, density and temperature measurements. In this paper we demonstrate a new, robust Liquid Crystal Point Diffraction Interferometer (LCPDI) that includes phase stepping and can provide accurate data even in the presence of intense acoustic fields. This novel common path interferometer (LCPDI) was developed to overcome difficulties with the Mach Zehnder interferometer in vibratory environments and is applied here to the case of a supersonic shock- containing jet. The environmentally insensitive LCPDI that is easy to align and capable of measuring optical wavefronts with high accuracy is briefly described, then integrated line of sight density data from the LCPDI for two underexpanded jets are presented.

Mercer, Carolyn R.↗

NASA NTRS2011

Launch Vehicle Demonstrator Using Shuttle Assets

The Marshall Space Flight Center Advanced Concepts Office (ACO) has the leading role for NASA s preliminary conceptual launch vehicle design and performance analysis. Over the past several years the ACO Earth-to-Orbit Team has evaluated thousands of launch vehicle concept variations for a multitude of studies including agency-wide efforts such as the Exploration Systems Architecture Study (ESAS), Constellation, Heavy Lift Launch Vehicle (HLLV), Heavy Lift Propulsion Technology (HLPT), Human Exploration Framework Team (HEFT), and Space Launch System (SLS). NASA plans to continue human space exploration and space station utilization. Launch vehicles used for heavy lift cargo and crew will be needed. One of the current leading concepts for future heavy lift capability is an inline one and a half stage concept using solid rocket boosters (SRB) and based on current Shuttle technology and elements. Potentially, the quickest and most cost-effective path towards an operational vehicle of this configuration is to make use of a demonstrator vehicle fabricated from existing shuttle assets and relying upon the existing STS launch infrastructure. Such a demonstrator would yield valuable proof-of-concept data and would provide a working test platform allowing for validated systems integration. Using shuttle hardware such as existing RS-25D engines and partial MPS, propellant tanks derived from the External Tank (ET) design and tooling, and four-segment SRB s could reduce the associated upfront development costs and schedule when compared to a concept that would rely on new propulsion technology and engine designs. There are potentially several other additional benefits to this demonstrator concept. Since a concept of this type would be based on man-rated flight proven hardware components, this demonstrator has the potential to evolve into the first iteration of heavy lift crew or cargo and serve as a baseline for block upgrades. This vehicle could also serve as a demonstration and test platform for the Orion Program. Critical spacecraft systems, re-entry and recovery systems, and launch abort systems of Orion could also be demonstrated in early test flights of the launch vehicle demo. Furthermore, an early demonstrator of this type would provide a stop-gap for retaining critical human capital and infrastructure while affording the current emerging generation of young engineers opportunity to work with and capture lessons learned from existing STS program offices and personnel, who were integral in the design and development of the Space Shuttle before these resources are no longer available. The objective of this study is to define candidate launch vehicle demonstration concepts that are based on Space Shuttle assets and determine their performance capabilities and how these demonstration vehicles could evolve to a heavy lift capability to low earth orbit.

Threet, Grady E., Jr.↗

NASA NTRS2016

Solar System Exploration Research Virtual Institute: Year Three Annual Report 2016

NASA's Solar System Exploration Research Virtual Institute (SSERVI) is pleased to present the 2016 Annual Report. Each year brings new scientific discoveries, technological breakthroughs, and collaborations. The integration of basic research and development, industry and academic partnerships, plus the leveraging of existing technologies, has further opened a scientific window into human exploration. SSERVI sponsorship by the NASA Science Mission Directorate (SMD) and Human Exploration and Operations Mission Directorate (HEOMD) continues to enable the exchange of insights between the human exploration and space science communities, paving a clearer path for future space exploration. SSERVI provides a unique environment for scientists and engineers to interact within multidisciplinary research teams. As a virtual institute, the best teaming arrangements can be made irrespective of the geographical location of individuals or laboratory facilities. The interdisciplinary science that ensues from virtual and in-person interactions, both within the teams and across team lines, provides answers to questions that many times cannot be foreseen. Much of this research would not be accomplished except for the catalyzing, collaborative environment enabled by SSERVI. The SSERVI Central Office, located at NASA Ames Research Center in Silicon Valley, California, provides the leadership, guidance and technical support that steers the virtual institute. At the start of 2016, our institute had nine U.S. teams, each mid-way through their five-year funding cycle, plus nine international partnerships. However, by the end of the year we were well into the selection of four new domestic teams, selected through NASA's Cooperative Agreement Notice (CAN) process, and a new international partnership. Understanding that human and robotic exploration is most successful as an international endeavor, international partnerships collaborate with SSERVI domestic teams on a no-exchange of funds basis, but they bring a richness to the institute that is priceless. The international partner teams interact with the domestic teams in a number of ways, including sharing students, scientific insights, and access to facilities. We are proud to introduce our newest partnership with the Astrophysics and Planetology Research Institute (IRAP) in Toulouse, France. In 2016, Principal Investigator Dr. Patrick Pinet assembled a group of French researchers who will contribute scientific and technological expertise related to SSERVI research. SSERVI's domestic teams compete for five-year funding opportunities through proposals to a NASA CAN every few years. Having overlapping proposal selection cycles allows SSERVI to be more responsive to any change in direction NASA might experience, while providing operational continuity for the institute. Allowing new teams to blend with the more seasoned teams preserves corporate memory and expands the realm of collaborative possibilities. A key component of SSERVI's mission is to grow and maintain an integrated research community focused on questions related to the Moon, Near-Earth asteroids, and the moons of Mars. The strong community response to CAN-2 demonstrated the health of that effort. NASA Headquarters conducted the peer-review of 22 proposals early in 2017 and, based on recommendations from the SSERVI Central Office and NASA SSERVI program officers, the NASA selecting officials determined the new teams in the spring of 2017. We are pleased to welcome the CAN-2 teams into the institute, and look forward to the collaborations that will develop with the current teams. The new teams are: The Network for Exploration and Space Science (NESS) team (Principal Investigator (PI) Prof. Jack Burns/U. Colorado); the Exploration Science Pathfinder Research for Enhancing Solar System Observations (ESPRESSO) team (PI Dr. Alex Parker/Southwest Research Institute); the Toolbox for Research and Exploration (TREX) team (PI Dr. Amanda Hendrix/ Planetary Science Institute); and the Radiation Effects on Volatiles and Exploration of Asteroids & Lunar Surfaces (REVEALS) team (PI Prof. Thomas Orlando/ Georgia Institute of Technology). In this report, you will find an overview of the 2016 leadership activities of the SSERVI Central Office, reports prepared by the U.S. teams from CAN-1, and achievements from several of the SSERVI international partners. Reflecting on the past year's discoveries and advancements serves as a potent reminder that there is still a great deal to learn about NASA's target destinations. Innovation in the way we access, sample, measure, visualize, and assess our target destinations is needed for further discovery. At the same time, let us celebrate how far we have come, and strongly encourage a new generation that will make the most of future opportunities.

Pendleton, Yvonne↗

NASA NTRS1989

HERMIES-3: A step toward autonomous mobility, manipulation, and perception

HERMIES-III is an autonomous robot comprised of a seven degree-of-freedom (DOF) manipulator designed for human scale tasks, a laser range finder, a sonar array, an omni-directional wheel-driven chassis, multiple cameras, and a dual computer system containing a 16-node hypercube expandable to 128 nodes. The current experimental program involves performance of human-scale tasks (e.g., valve manipulation, use of tools), integration of a dexterous manipulator and platform motion in geometrically complex environments, and effective use of multiple cooperating robots (HERMIES-IIB and HERMIES-III). The environment in which the robots operate has been designed to include multiple valves, pipes, meters, obstacles on the floor, valves occluded from view, and multiple paths of differing navigation complexity. The ongoing research program supports the development of autonomous capability for HERMIES-IIB and III to perform complex navigation and manipulation under time constraints, while dealing with imprecise sensory information.

Weisbin, C. R.↗

NASA NTRS2001

Achieving End-to-End QoS in the Next Generation Internet: Integrated Services Over Differentiated Service Networks

Currently there are two approaches to provide Quality of Service (QoS) in the next generation Internet: An early one is the Integrated Services (IntServ) with the goal of allowing end-to-end QoS to be provided to applications; the other one is the Differentiated Services (DiffServ) architecture providing QoS in the backbone. In this context, a DiffServ network may be viewed as a network element in the total end-to-end path. The objective of this paper is to investigate the possibility of providing end-to-end QoS when IntServ runs over DiffServ backbone in the next generation Internet. Our results show that the QoS requirements of IntServ applications can be successfully achieved when IntServ traffic is mapped to the DiffServ domain in next generation Internet.

Bai, Haowei↗

NASA NTRS2000

Next Generation CTAS Tools

The FAA's Free Flight Phase 1 Office is in the process of deploying the current generation of CTAS tools, which are the Traffic Management Advisor (TMA) and the passive Final Approach Spacing Tool (pFAST), at selected centers and airports. Research at NASA is now focussed on extending the CTAS software and computer human interfaces to provide more advanced capabilities. The Multi-center TMA (McTMA) is designed to operate at airports where arrival flows originate from two or more centers whose boundaries are in close proximity to the TRACON boundary. McTMA will also include techniques for routing arrival flows away from congested airspace and around airspace reserved for arrivals into other hub airports. NASA is working with FAA and MITRE to build a prototype McTMA for the Philadelphia airport. The active Final Approach Spacing Tool (aFAST) provides speed and heading advisories to help controllers achieve accurate spacing between aircraft on final approach. These advisories will be integrated with those in the existing pFAST to provide a set of comprehensive advisories for controlling arrival traffic from the TRACON boundary to touchdown at complex, high-capacity airports. A research prototype of aFAST, designed for the Dallas-Fort Worth is in an advanced stage of development. The Expedite Departure Path (EDP) and Direct-To tools are designed to help controllers guide departing aircraft out of the TRACON airspace and to climb to cruise altitude along the most efficient routes.

Erzberger, Heinz↗

NASA NTRS2001

Achieving End-to-End QoS in the Next Generation Internet: Integrated Services over Differentiated Service Networks

Bai, Haowei↗

NASA NTRS2015

Germinating the 2050 Cis-Lunar Econosphere

In early 2013, Marshall Space Flight Center's upper management chartered a diverse team for a six-week 'sprint' to speculate (in a disciplined manner) and paint (with broad brush strokes) a picture of how earth, space, and public/private entities might be operating and relating to each other... in the year 2100. Two 12-person groups of civil servants, one with members having 15 years or less of NASA experience and the other with more senior members, worked independently and then compared and integrated their conclusions. In 2014, the 'Space 2100' team, with some new team members and different group boundaries, ran a longer sprint to a) develop more detailed estimates of the operations and economics of space activities in the vicinity of the Earth and Moon in the 2050 time frame, b) identify evolutionary paths, barriers, and opportunities, and c) suggest actions and philosophies to enable and invigorate progress towards the vision. This paper explores Space 2100's first two sprints and their projections of NASA's role in what will likely be a highly networked, international space industry and cis-lunar infrastructure.

Scott, David W.↗

NASA NTRSDate not supplied

A Distributed Approach to High-Rate Delay Tolerant Networking Within a Virtualized Environment

The High-Rate Delay Tolerant Networking (HDTN) project has taken a distributed service-based approach to the development of a highly efficient delay tolerant networking (DTN) implementation. Through the analysis of many DTN implementations, system and mission requirements as well as the DTN protocol specifications, HDTN has worked to infuse modern computing technologies into the NASA approach to interplanetary networking. The initial use case of the HDTN software runs on a hypervisor representative of the International Space Station (ISS) DTN Gateway. In this scenario, multiple emulated payloads will send science data through HDTN to a mission operations center. HDTN will provide store and forward capability as well as network flow management. This paper discusses the infusion path of cognitive networking technologies in the NASA Space Communications and Navigation (SCaN) networks using the DTN architecture and protocols as the basis for cognitive routing and network management capabilities. HDTN has been developing the Bundle Protocol encoding and decoding mechanisms and messaging framework that can be used as the basis for integrating DTN with various learning and decision-making processes. The concepts of distributed computing, network virtualization, software defined networking and delay tolerant networking are basic building blocks which will further the development of cognitive networking. In addition to discussion of the HDTN software development and testing, this paper examines the role that each of these technologies play in the evolution of the current state of space networking into an intelligent network of networks.

Rachel Mary Dudukovich↗

NASA NTRS2021

Ambient Performance Testing of the CubeSat Infrared Atmospheric Sounder (CIRAS)

Hyperspectral infrared measurements of Earth’s atmosphere from space have proven their value for weather forecasting, climate science and atmospheric composition. The CubeSat Infrared Atmospheric Sounder (CIRAS) instrument will demonstrate a fully functional infrared temperature, water vapor and carbon monoxide sounder in a CubeSat sized volume for at least an order of magnitude lower cost than legacy systems. Design for a CubeSat significantly reduces cost of access to space and enables flight in a constellation to reduce revisit time and enable new measurements including 3D winds. A technology demonstration of CIRAS is currently under development at JPL. The effort has completed integration and ambient testing of a high fidelity brassboard, complete with the flight configured optics assembly developed by Ball Aerospace with a JPL Immersion Grating and Black Silicon Entrance Slit. The brassboard includes a flight-configured High Operating Temperature Barrier Infrared Detector (HOT-BIRD) mounted in an Integrated Dewar Cryocooler Assembly (IDCA), enabling testing in the ambient environment. Ambient testing included radiometric testing of the system to characterize the instrument operability and NEdT. Spatial testing was performed to characterize the system line spread function (LSF) in two axes and report FWHM of the LSF. Spectral testing involved an air path test to characterize the spectral/spatial transformation matrix, and an etalon was used to measure the Spectral Response Functions (SRFs). Results of the testing show the CIRAS performs exceptionally well and meets the key performance required of the system. The end result of testing is the CIRAS instrument now meets TRL 4 with confidence in a brassboard configuration ready for thermal vacuum (TVac) testing necessary to achieve TRL 5 for the system.

Wilson, Robert C.↗

NASA NTRS1991

Direct glass bonded high specific power silicon solar cells for space applications

A lightweight, radiation hard, high performance, ultra-thin silicon solar cell is described that incorporates light trapping and a cover glass as an integral part of the device. The manufacturing feasibility of high specific power, radiation insensitive, thin silicon solar cells was demonstrated experimentally and with a model. Ultra-thin, light trapping structures were fabricated and the light trapping demonstrated experimentally. The design uses a micro-machined, grooved back surface to increase the optical path length by a factor of 20. This silicon solar cell will be highly tolerant to radiation because the base width is less than 25 microns making it insensitive to reduction in minority carrier lifetime. Since the silicon is bonded without silicone adhesives, this solar cell will also be insensitive to UV degradation. These solar cells are designed as a form, fit, and function replacement for existing state of the art silicon solar cells with the effect of simultaneously increasing specific power, power/area, and power supply life. Using a 3-mil thick cover glass and a 0.3 g/sq cm supporting Al honeycomb, a specific power for the solar cell plus cover glass and honeycomb of 80.2 W/Kg is projected. The development of this technology can result in a revolutionary improvement in high survivability silicon solar cell products for space with the potential to displace all existing solar cell technologies for single junction space applications.

Dinetta, L. C.↗

NASA NTRS1999

Hardware and Methods of the Optical End-to-End Test of the Far Ultraviolet Spectroscopic Explorer (FUSE)

The Far Ultraviolet Spectroscopic Explorer (FUSE), currently being tested and scheduled for a 1999 launch, is an astrophysics satellite designed to provide high spectral resolving power (Lambda/(Delta)Lambda = 24,000-30,000) over the interval 90.5-118.7 nm. The FUSE optical path consists of four co-aligned, normal incidence, off-axis parabolic, primary mirrors which illuminate separate Rowland circle spectrograph channels equipped with holographic gratings and delay line microchannel plate detectors. We describe the hardware and methods used for the optical end-to-end test of the FUSE instrument during satellite integration and test. Cost and schedule constraints forced us to devise a simplified version of the planned optical test which occurred in parallel with satellite thermal-vacuum testing. The optical test employed a collimator assembly which consisted of four co-aligned, 15" Cassegrain telescopes which were positioned above the FUSE instrument, providing a collimated beam for each optical channel. A windowed UV light source, remotely adjustable in three axes, was mounted at the focal plane of each collimator. Problems with the UV light sources, including high F-number and window failures, were the only major difficulties encountered during the test. The test succeeded in uncovering a significant problem with the secondary structure used for the instrument closeout cavity and, furthermore, showed that the mechanical solution was successful. The hardware was also used extensively for simulations of science observations, providing both UV light for spectra and visible light for the fine error sensor camera.

Conard, Steven J.↗

NASA NTRS2009

Low-Pressure, Field-Ionizing Mass Spectrometer

A small mass spectrometer utilizing a miniature field ionization source is now undergoing development. It is designed for use in a variety of applications in which there are requirements for a lightweight, low-power-consumption instrument that can analyze the masses of a wide variety of molecules and ions. The device can operate without need for a high-vacuum, carrier-gas feed radioactive ionizing source, or thermal ionizer. This mass spectrometer can operate either in the natural vacuum of outer space or on Earth at any ambient pressure below 50 torr (below about 6.7 kPa) - a partial vacuum that can easily be reached by use of a small sampling pump. This mass spectrometer also has a large dynamic range - from singly charged small gas ions to deoxyribonucleic acid (DNA) fragments larger than 104 atomic mass units - with sensitivity adequate for detecting some molecules and ions at relative abundances of less than one part per billion. This instrument (see figure) includes a field ionizer integrated with a rotating-field mass spectrometer (RFMS). The field ionizer effects ionization of a type characterized as "soft" in the art because it does not fragment molecules or initiate avalanche arcing. What makes the "soft" ionization mode possible is that the distance between the ionizing electrodes is less than mean free path for ions at the maximum anticipated operating pressure, so that the ionizer always operates on the non-breakdown side of the applicable Paschen curve (a standard plot of breakdown potential on the ordinate and pressure electrode separation on the abscissa). The field ionizer in this instrument is fabricated by micromachining a submicron-thick membrane out of an electrically nonconductive substrate, coating the membrane on both sides to form electrodes, then micromachining small holes through the electrodes and membrane. Because of the submicron electrode separation, even a potential of only 1 V applied between the electrodes gives rise to an electric field with a strength of in excess of a megavolt per meter strong enough to ionize any gas molecules passing through the holes. An accelerator grid and an electrostatic deflector focus the ions from the field ionizer into the rotating-field cell of the RFMS. The potentials applied to the electrodes of the cell to generate the rotating electric field typically range from 1 to 13 V. The ions travel in well-defined helices within this cell, after which they are collected in a Faraday cup. The mass of most of the molecules reaching the Faraday cup decreases with increasing frequency of rotation of the electric field in the cell. Therefore, the frequency of rotation of the electric field is made to vary in order to scan through a desired range of ion masses: For example, lightweight gas molecules are scanned at frequencies in the megahertz range, while DNA and other large organic molecules are scanned at kilohertz frequencies.

Hartley, Frank↗

NASA NTRSDate not supplied

Gateway: Humanity’s Next Utilization Platform

The National Aeronautics and Space Administration’s (NASA) Gateway Program is an international collaboration to establish humanity’s first space station in lunar orbit. Gateway is a critical element of the Artemis missions that will create a sustained human presence on and around the Moon and chart a path for human missions to Mars. As a platform for science, Gateway builds on decades of success on the International Space Station by extending utilization capabilities from low-Earth orbit to deep space to leverage opportunities specific to the deep space lunar environment. NASA leads the Gateway Program and serves as the integrator of spaceflight capabilities and contributions of U.S. commercial and international partners, including the European Space Agency (ESA), Japanese Aerospace Exploration Agency (JAXA) and the Canadian Space Agency (CSA), to develop Gateway and leverage unique opportunities presented by its location in deep space. This paper provides: Gateway spacecraft overview, internal and external accommodations, resources for utilization, and vantage point for Earth, Sun, and Moon observations. Three utilization payloads have already been selected to fly on Gateway as part of the initial modules, the Habitation and Logistics Outpost (HALO) and Power and Propulsion Element (PPE): European Radiation Sensors Array (ERSA), Heliophysics Environmental and Radiation Measurement Experiment Suite (HERMES), and Internal Dosimeter Array (IDA). This paper will provide a short summary of each payload, the value behind conducting each payload, and share an overview of future utilization goals of Gateway.

Stephanie Buskirk Dudley↗

NASA NTRS1979

Procedure for noise prediction and optimization of advanced technology propellers

The sound field due to a propeller operating at supersonic tip speed in a uniform flow was investigated. Using the fact that the wave front in a uniform stream is a convected sphere, the fundamental solution to the convected wave equation was easily obtained. The Fourier coefficients of the pressure signature were obtained by a far field approximation, and are expressed as an integral over the blade platform. It is shown that cones of silence exist fore and aft the propeller plane. The semiapex angles are shown. These angles are independent of the individual Mach components such as the flight Mach number and the rotation Mach number. The result is confirmed by the computation of the ray path of the emitted Mach waves. The Doppler amplification factor strengthens the signal behind the propeller while it weakens that upstream.

Jou, W. H.↗