Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Energy Profiles”

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 469 records · Page 26

4U 1626-67 - The binary with the smallest known mass function

The pulsing X-ray source 4U 1626-67 is an accreting neutron star in a binary system with a very low mass companion. The source was observed by Exosat continuously for 23 hr on March 30-31, 1986 UT. It is found that, if the orbital inclination angle equals 90 deg, the optical companion star has a mass of less than about 0.002 solar mass; however, it is found that a companion star mass of greater than about 0.06 solar mass is required if gravitational radiation is responsible for driving the mass transfer in this system. Also presented are results on flaring activity in the system on time scales of about 1000 s, the energy-dependent pulse profiles, and the pulse period history over the past decade.

Levine, A.↗

Quasilinear saturation of forced current sheet tearing modes

Numerical studies of tearing modes in a nearly singular forced current sheet equilibrium (Liewer and Payne, 1990) show that the modes saturate quasilinearly when the width of the magnetic island formed by the reconnection is on the order of several times the linear mode width which scales as approximately (kS) exp -2/5, where S is the Lundquist number and k is the wavenumber. The modes saturate quasilinearly by flattening the current profile, converting magnetic energy into plasma energy. The longer wavelength modes, which saturate at higher levels, release the most energy. These modes may, nonlinearly, play a role in coronal heating when sharp current sheets form as a result of global magnetic stresses.

Liewer, Paulett C.↗

A predictor-corrector guidance algorithm for use in high-energy aerobraking system studies

A three-degree-of-freedom predictor-corrector guidance algorithm has been developed specifically for use in high-energy aerobraking performance evaluations. The present study reports on both the development and capabilities of this guidance algorithm to the design of manned Mars aero-braking vehicles. Atmospheric simulations are performed to demonstrate the applicability of this algorithm and to evaluate the effect of atmospheric uncertainties upon the mission requirements. The off-nominal conditions simulated result from atmospheric density and aerodynamic characteristic mispredictions. The guidance algorithm is also used to provide relief from the high deceleration levels typically encountered in a high-energy aerobraking mission profile. Through this analysis, bank-angle modulation is shown to be an effective means of providing deceleration relief. Furthermore, the capability of the guidance algorithm to manage off-nominal vehicle aerodynamic and atmospheric density variations is demonstrated.

Braun, Robert D.↗

Accreting Millisecond Pulsars and Fundamental Physics

X-ray emission from the surfaces of rapidly rotating neutron stars encodes information about their global properties as well as physical conditions locally. Detailed modelling of, for example, the energy dependent pulse profiles observed from accreting millisecond pulsars and thermonuclear burst oscillations can be used to derive constraints on the masses and radii of neutron stars. These measurements provide direct information on the properties of the dense matter equation of state of the supranuclear density matter in their interiors. Study of absorption lines created in the surface layers can also provide measurements of masses and radii, and may be able to probe aspects of relativistic gravity, such as frame dragging. I will discuss the results of recent efforts to carry out such measurements and their implications for the properties of dense matter.

Strohmayer, Tod↗

Peculiar Outburst of A 0535+26 Observed with INTEGRAL, RXTE and Suzaku

A normal outburst of the Be/X-ray binary system A0535+26 has taken place in August 2009. It is the fourth in a series of normal outbursts that have occurred around the periastron passage of the source. but is unusual by starting at an earlier orbital phase and by presenting a peculiar double-peaked light curve. A first "flare" (lasting about 9 days from M.ID 55043 on) reached a flux of 440 mCrab. The flux then decreased to less than 220 mCrab. and increased again reaching 440 mCrab around the periastron at MJD 55057. Target of Opportunity observations have been performed with INTEGRAL. RXTE and Suzaku. First results of these observations are presented. with special emphasis on the cyclotron lines present in the X-ray spectrum of the source. as well as in the pulse period and energy dependent pulse profiles of the source

Caballero, I.↗

X-ray Proper Motions and Shock Speeds along the Northwest Rim of SN1006

We report the results of an X-ray proper motion measurement for the NW rim of SN 1006, carried out by comparing Chandra observations from 2001 and 2012. The NW limb has predominantly thermal X-ray emission, and it is the only location in SN 1006 with signi cant optical emission: a thin, Balmer-dominated lament. For most of the NW rim, the proper motion is approximately equal to 0.30"yr(exp -1), essentially the same as has been measured from the H alpha lament. Isolated regions of the NW limb are dominated by nonthermal emission, and here the proper motion is much higher, 0:49"yr(exp -1), close to the value measured in X-rays along the much brighter NE limb, where the X-rays are overwhelmingly nonthermal. At the 2.2 kpc distance to SN 1006, the proper motions imply shock velocities of approximately 3000 kms(exp -1) and approximately 5000 kms(exp -1) in the thermal and nonthermal regions, respectively. A lower velocity behind the H alpha filament is consistent with the picture that SN 1006 is encountering denser gas in the NW, as is also suggested by its overall morphology. In the thermally-dominated portion of the X-ray shell, we also see an o set in the radial profiles at different energies; the 0.5-0.6 keV peak dominated by O VII is closer to the shock front than that of the 0.8-3 keV emission|due to the longer times for heavier elements to reach ionization states where they produce strong X-ray emission.

Katsuda, Satoru↗

NASA's Space Launch System: Building a New Capability for Discovery

Designed to enable human space exploration missions, including eventually landings on Mars, NASA's Space Launch System (SLS) represents a unique launch capability with a wide range of utilization opportunities, from delivering habitation systems into the lunar vicinity to high-energy transits through the outer solar system. Substantial progress has been made toward the first launch of the initial configuration of SLS, which will be able to deliver more than 70 metric tons of payload into low Earth orbit (LEO). The vehicle will then be evolved into more powerful configurations, culminating with the capability to deliver more than 130 metric tons to LEO. The initial configuration will be able to deliver greater mass to orbit than any contemporary launch vehicle, and the evolved configuration will have greater performance than the Saturn V rocket that enabled human landings on the moon. SLS will also be able to carry larger payload fairings than any contemporary launch vehicle, and will offer opportunities for co-manifested and secondary payloads. Because of its substantial mass-lift capability, SLS will also offer unrivaled departure energy, enabling mission profiles currently not possible. The basic capabilities of SLS have been driven by studies on the requirements of human deep-space exploration missions, and continue to be validated by maturing analysis of Mars mission options. Early collaboration with science teams planning future decadal-class missions have contributed to a greater understanding of the vehicle's potential range of utilization. As this paper will explain, SLS is making measurable progress toward becoming a global infrastructure asset for robotic and human scouts of all nations by providing the robust space launch capability to deliver sustainable solutions for exploration.

Creech, Stephen D.↗

NASA's Space Launch System: An Evolving Capability for Exploration

Designed to enable human space exploration missions, including eventually landings on Mars, NASA's Space Launch System (SLS) represents a unique launch capability with a wide range of utilization opportunities, from delivering habitation systems into the "proving ground" of lunar-vicinity space to enabling high-energy transits through the outer solar system. Substantial progress has been made toward the first launch of the initial configuration of SLS, which will be able to deliver more than 70 metric tons of payload into low Earth orbit (LEO). Preparations are also underway to evolve the vehicle into more powerful configurations, culminating with the capability to deliver more than 130 metric tons to LEO. Even the initial configuration of SLS will be able to deliver greater mass to orbit than any contemporary launch vehicle, and the evolved configuration will have greater performance than the Saturn V rocket that enabled human landings on the moon. SLS will also be able to carry larger payload fairings than any contemporary launch vehicle, and will offer opportunities for co-manifested and secondary payloads. Because of its substantial mass-lift capability, SLS will also offer unrivaled departure energy, enabling mission profiles currently not possible. The basic capabilities of SLS have been driven by studies on the requirements of human deep-space exploration missions, and continue to be validated by maturing analysis of Mars mission options, including the Global Exploration Roadmap. Early collaboration with science teams planning future decadal-class missions have contributed to a greater understanding of the vehicle's potential range of utilization. As SLS draws closer to its first launch, the Program is maturing concepts for future capability upgrades, which could begin being available within a decade. These upgrades, from multiple unique payload accommodations to an upper stage providing more power for inspace propulsion, have ramifications for a variety of missions, from human exploration to robotic science.

Robinson, Kimberly F.↗

NASA's Space Launch System Mission Capabilities for Exploration

Designed to enable human space exploration missions, including eventual landings on Mars, NASA's Space Launch System (SLS) represents a unique launch capability with a wide range of utilization opportunities, from delivering habitation systems into the lunar vicinity to high-energy transits through the outer solar system. Developed with the goals of safety, affordability and sustainability in mind, SLS is a foundational capability for NASA's future plans for exploration, along with the Orion crew vehicle and upgraded ground systems at the agency's Kennedy Space Center. Substantial progress has been made toward the first launch of the initial configuration of SLS, which will be able to deliver more than 70 metric tons of payload into low Earth orbit (LEO), greater mass-to-orbit capability than any contemporary launch vehicle. The vehicle will then be evolved into more powerful configurations, culminating with the capability to deliver more than 130 metric tons to LEO, greater even than the Saturn V rocket that enabled human landings on the moon. SLS will also be able to carry larger payload fairings than any contemporary launch vehicle, and will offer opportunities for co-manifested and secondary payloads. Because of its substantial mass-lift capability, SLS will also offer unrivaled departure energy, enabling mission profiles currently not possible. Early collaboration with science teams planning future decadal-class missions have contributed to a greater understanding of the vehicle's potential range of utilization. This presentation will discuss the potential opportunities this vehicle poses for the planetary sciences community, relating the vehicle's evolution to practical implications for mission capture. As this paper will explain, SLS will be a global launch infrastructure asset, employing sustainable solutions and technological innovations to deliver capabilities for space exploration to power human and robotic systems beyond our Moon and in to deep space.

Creech, Stephen D.↗

NASA'S Space Launch System Mission Capabilities for Exploration

Designed to enable human space exploration missions, including eventual landings on Mars, NASA’s Space Launch System (SLS) represents a unique launch capability with a wide range of utilization opportunities, from delivering habitation systems into the lunar vicinity to high-energy transits through the outer solar system. Developed with the goals of safety, affordability and sustainability in mind, SLS is a foundational capability for NASA’s future plans for exploration, along with the Orion crew vehicle and upgraded ground systems at the agency’s Kennedy Space Center. Substantial progress has been made toward the first launch of the initial configuration of SLS, which will be able to deliver more than 70 metric tons of payload into low Earth orbit (LEO), greater mass-to-orbit capability than any contemporary launch vehicle. The vehicle will then be evolved into more powerful configurations, culminating with the capability to deliver more than 130 metric tons to LEO, greater even than the Saturn V rocket that enabled human landings on the moon. SLS will also be able to carry larger payload fairings than any contemporary launch vehicle, and will offer opportunities for co-manifested and secondary payloads. Because of its substantial mass-lift capability, SLS will also offer unrivaled departure energy, enabling mission profiles currently not possible. Early collaboration with science teams planning future decadal-class missions have contributed to a greater understanding of the vehicle’s potential range of utilization. This presentation will discuss the potential opportunities this vehicle poses for the planetary sciences community, relating the vehicle’s evolution to practical implications for mission capture. As this paper will explain, SLS will be a global launch infrastructure asset, employing sustainable solutions and technological innovations to deliver capabilities for space exploration to power human and robotic systems beyond our Moon and in to deep space.

Creech, Stephen D.↗

Physical Models for Accreting Pulsars at High Luminosity

A new window for better understanding the accretion onto strongly magnetized neutron stars in X-ray binaries is opening. In these systems the accreted material follows the magnetic field lines as it approaches the neutron star, forming accretion columns above the magnetic poles. The plasma falls toward the neutron star surface at near-relativistic speeds, losing energy by emitting X-rays. The X-ray spectral continua are commonly described using phenomenological models, i.e., power laws with different types of curved cut-offs at higher energies. Here we consider high luminosity pulsars. In these systems the mass transfer rate is high enough that the accreting plasma is thought to be decelerated in a radiation-dominated radiative shock in the accretion columns. While the theory of the emission from such shocks had already been developed by 2007, a model for direct comparison with X-ray continuum spectra in xspec or isis has only recently become available. Here we analyze the broadband X-ray spectra of the accreting pulsars Centaurus X-3 and 4U1626-67 obtained withNuSTAR. We present results from traditional empirical modeling as well as successfully apply the radiation-dominated radiative shock model. We also fit the energy-dependent pulse profiles of 4U 1626-67 using a new relativistic light bending model.

Pottschmidt, Katja↗

Single-mode Fiber and Few-Mode Fiber Photonic Lanterns Performance Evaluated for Use in a Scalable Real-Time Photon Counting Ground Receiver

Photonic lanterns provide an efficient way of coupling light from a single large-core fiber to multiple small-core fibers. This capability is of interest for space to ground communication applications. In these applications, the optical ground receivers require high-efficiency coupling from an atmospherically distorted focus spot to multiple fiber coupled single pixel super-conducting nanowire detectors. This paper will explore the use of photonic lanterns in a real-time ground receiver that is scalable and constructed with commercial parts. The number of small-core fibers that make a photonic lantern determines the number of spatial modes that they couple. For instance, lanterns made with n number of single-mode fibers can couple n number of spatial modes. Although the laser transmitted from a spacecraft originates as a Gaussian shape, the atmosphere distorts the beam profile by scattering energy into higher-order spatial modes. Therefore, if a ground receiver is sized for a target data rate with n number of detectors, the corresponding lantern made with single-mode fibers will couple n number of spatial modes. The energy of the transmitted beam scattered into spatial modes higher than n will be lost. This paper shows this loss may be reduced by making lanterns with few-mode fibers instead of single-mode fibers, increasing the number of spatial modes that can be coupled and therefore increasing the coupling efficiency to single pixel, single photon detectors. The free space to fiber coupling efficiency of these two types of photonic lanterns are compared over a range of the free-space coupling numerical apertures and mode field diameters. Results indicate the few mode fiber lantern has higher coupling efficiency for telescopes with longer focal lengths under higher turbulent conditions. Also presented is analysis of the jitter added to the system by the lanterns, showing the few-mode fiber photonic lantern adds more jitter than the single-mode fiber lantern, but less than a multimode fiber.

photon counting↗

Space Launch System Payload Stage Capability for Ultra-High Characteristic Energy Missions

The Space Launch System (SLS) vehicle is NASA’s cornerstone capability for a new era of human and robotic exploration of deep space. The unrivalled performance of SLS provides the capability to launch the first woman and next man to walk on the lunar surface and to support development of a sustained human presence in cislunar space, and ultimately human missions to Mars. As an evolvable capability with unique launch performance, the opportunities enabled by SLS also include game-changing benefits for science missions, including probes to the outer solar system and beyond. For the last two years, the SLS Program has worked with the Interstellar Probe team at the Johns Hopkins University Applied Physics Laboratory(APL) to provide data that describe how SLS could support a mission that would break through the boundary of the heliosphere and into pristine interstellar space only a decade after launch, enabling earlier science return and greatly increasing spacecraft life in the interstellar medium. In record-breaking time, the ISP as launched on SLS may answer questions raised by the extended mission of NASA’s Voyager spacecraft. While SLS and its efficient Exploration Upper Stage (EUS) offer benefits for exploration of the outer planets, adding one or more additional stages to this architecture makes it even more capable for missions beyond our solar system, offering more realistically appealing flight times that would allow the mission scientists to reap the rewards of exploration. During the time the SLS Program has been working with the Interstellar Probe team, it has identified an expedited path to the Block 2 capability planned for the Interstellar Probe mission, and further matured performance numbers for diverse multi-stage configurations using a combination of commercially available liquid hydrogen (LH2)/liquid oxygen (LOX) upper stages and solid motor kick stages. That work has demonstrated the SLS payload stage capability provides significant benefits and opens trade space for multiple missions in consideration during planning for the next Planetary Science and Astrobiology Decadal Survey. This presentation details the significant benefits SLS can provides for very high characteristic (C3) energy missions by coupling the capabilities of SLS to current commercial rocket propulsion stage systems. These capabilities are explored specifically in the context of an Interstellar Probe architecture in which a small, capable science probe, coupled with carefully tailored mission design trajectories, could be used to explore the outer solar system and the interstellar medium. The presentation will also address the operational logistics of integrating such a mission, explaining the options available for “non-standard” SLS payloads, including processing those with radioisotope power generators or additional propulsion stages. An SLS system overview and capabilities will be presented, along with vehicle configuration and orbit performance capability studies, explaining how SLS is enabling for a variety of high-energy science mission profiles, including launching an exploratory probe bound for interstellar space only a decade after launch.

Rob Stough↗

Timing of the Accreting Millisecond Pulsar IGR J17591-2342: Evidence of Spin-down during Accretion

We report on the phase-coherent timing analysis of the accreting millisecond X-ray pulsar IGR J17591–2342, using Neutron Star Interior Composition Explorer (NICER) data taken during the outburst of the source between 2018 August 15 and 2018 October 17. We obtain an updated orbital solution of the binary system. We investigate the evolution of the neutron star spin frequency during the outburst, reporting a refined estimate of the spin frequency and the first estimate of the spin frequency derivative ( ˙ν ∼ −7 × 10−14 Hz s−1), confirmed independently from the modelling of the fundamental frequency and its first harmonic. We further investigate the evolution of the X-ray pulse phases adopting a physical model that accounts for the accretion material torque as well as the magnetic threading of the accretion disc in regions where the Keplerian velocity is slower than the magnetosphere velocity. From this analysis we estimate the neutron star magnetic field Beq = 2.8(3) × 108 G. Finally, we investigate the pulse profile dependence on energy finding that the observed behaviour of the pulse fractional amplitude and lags as a function of energy is compatible with the down-scattering of hard X-ray photons in the disc or the neutron star surface.

A Sanna↗

A Physical Model Enhanced Data Driven Method for High-Resolution Residential Load Profile Generation

Residential buildings account for significant energy consumption, creating opportunities to offer grid services. As electric utilities seek to implement effective system operation strategies, understanding residential energy consumption patterns becomes essential; However, the time intervals of load profiles measured by utilities' smart meters are typically from 15 minutes to 60 minutes. The low-resolution data make it hard to extract appliance-level load information, which is critical for providing grid services. This paper presents a load profile generator designed to produce synthetic load profiles for residential buildings that emphasizes the importance of accurate representations of realistic energy consumption patterns. The generator takes realistic low-resolution residential load measurements and weather data as inputs, producing 1-minute interval profiles that match the characteristics of the original profiles. Further, this generator can be used to populate load profiles in areas where actual measurements are limited to improve the ability of utilities to analyze their distribution systems. By providing more high-resolution residential building load profiles, this tool supports electric utilities to enhance their residential building load control strategies and improve overall grid stability.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Design and engineering challenges of a multi-energy hard x-ray camera for long-pulse profile measurements at WEST tokamak

The WEST tokamak has recently been prepared for long pulse operation with a water-cooled full first wall. Heating is provided by radiofrequency systems, including Lower Hybrid Current Drive (LHCD). The Princeton Plasma Physics Laboratory has developed a multi-energy hard x-ray camera for profile measurements at WEST. The camera is based on a new generation of 2D pixel array detectors that allow the energy threshold to be independently set for each pixel. The diagnostic will provide spatial, temporal and energy resolved measurements of the hard x-ray emission from the full plasma cross-section, investigating several physical quantities such as the electron temperature from continuum emission, the fast electron tail density produced by radiofrequency current drive and runaway electrons, as well as characteristic tungsten x-rays due to beam-target emission at the edge. Overall, this work describes the engineering challenges that the WEST long pulse scenario poses for this diagnostic and how the design addresses and solves them. Vacuum, thermal stress and heat transfer calculations are presented and discussed.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Roles of Hydrogen Bonds and Alignment in Oriented Attachment of Gibbsite Nanoparticles: Insights from Molecular Dynamics

Oriented attachment (OA) of nanoparticles is an important crystal growth pathway in the synthesis of hierarchical structures. Although a significant understanding of OA has been made, the effect of atomistic misalignment and the roles of solvent/particle and particle/particle interactions on the structure–energy relationship during an OA remain elusive. In this study, we perform molecular dynamics simulations to calculate the potential of mean force (PMF) profile for gibbsite particle translation on a gibbsite slab with 1 or 2 intervening water layers (1W or 2W). The structures of the gibbsite surfaces and the confined water are analyzed to determine how the number and type of hydrogen bonds (H-bonds) influence the free energy profile during the translation. The PMF profile exhibits a periodicity of length 5.078 Å, consistent with the gibbsite unit cell size along the translation direction. The changes in the surface–water and water–water hydrogen bond network and water and surface OH groups’ orientations during the translation are strongly coupled with the changes in the PMF profile in the 1W case. However, when increasing the number of intervening water layers from 1W to 2W, the particle/slab misalignment becomes a dominant factor controlling the behavior of the PMF profile. We also establish a method to quantify misalignment between the particle and the slab, which exhibits a strong correlation with the free energy for the 2W case. These results shed more light into the roles of particle/slab misalignment and hydrogen bond network in the OA of mineral particles in aqueous solution.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Energy Snapshot - Commonwealth of the Northern Mariana Islands

This profile provides a snapshot of the energy landscape of the Commonwealth of the Northern Mariana Islands (CNMI), a commonwealth in political union with the United States that is located in the northern Pacific Ocean. CNMI's electricity rates for residential customers range from $0.21 to $0.35 U.S. dollars (USD) per kilowatt-hour (kWh), above the average U.S. residential rate of $0.13 USD/kWh.

44 EE - Strategic Programs, Energy Transition Init↗