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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 829 records · Page 46
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Dynamic Data-Driven SAR Image Reconstruction Using Multiple GPUs

According to the article, the reconstruction of nxn-pixel synthetic aperture radar (SAR) imagery using a backprojection algorithm incurs O(n 2 · m) cost, where m is the number of pulses. This paper presents dynamic data-driven multiresolution algorithms to speed up SAR backprojection on multiple graphics processing units (GPUs). A critical part of this spatially variant reconstruction process is load balancing, which circumvents asymmetric work assignment. Fine-tuned algorithms for GPUs are presented as a part of improving running time. Communication between processors is overlapped with GPU calculation to reduce communication time.

Engineering↗
DOE OSTI2015

Damage characterization in glass Fiber/Epoxy laminates using electronic speckle pattern interferometry

The degradation of the elastic properties of composite laminates with intralaminar cracks is caused by reduced stress in the damaged layer which is mainly due to two parameters: the crack opening displacement (COD) and the crack sliding displacement (CSD). In this paper these parameters are measured experimentally, providing laminate stiffness reduction models with valuable information for validation of used assumptions and for defining limits of their application. In particular, the displacement field on the edges of a [0/ +70{sub 4}/ −70{sub 4}]{sub s} glass fiber/epoxy laminate specimens with multiple intralaminar cracks is studied, and the COD and CSD dependence on the applied mechanical load is measured. The specimen full-field displacement measurement is carried out using ESPI (electronic speckle pattern interferometry). By studying the displacement discontinuities, the crack face displacements were measured. A comparison between the COD and the CSD (for the same crack) is performed.

36 MATERIALS SCIENCE↗
DOE OSTI2021

pnnl/grid_prediction

Two datadriven predictive approaches, namely, {\em Koopman Operator Theoretic (KOT)-based} model and {\em Graph Neural Network (GNN)-based model}, to enable effective power system state predictions. The KOT-based approaches (Robust DMD, deepDMD) capture the power system evolution as a linear dynamical system on an abstract space. The GNNs model the spatio-temporal correlations using graph convolutional network and are called Spatio-Temporal Graph Convolutional Network (STGCN). These predictive models are trained, tested and compared rigorously based on their predictions of frequencies in the IEEE 68 bus system when subjected to a disturbance. GridSTAGE framework developed at Pacific Northwest National Laboratory is leveraged to generate multiple datasets (in the form of PMU measurements) for training and testing by strategically creating load changes across the spatial locations of the network

Nandanoor, Sai Pushpak↗
DOE OSTI2025

A Scalable Hardware-and-Human-in-the-Loop Grid-interactive Efficient Building Equipment Performance Dataset

This project developed a publicly available, high-fidelity dataset about the interactions among humans, homes, and heat pumps supporting grid interactive efficient buildings to balance demand on the grid with comfort for occupants. Laboratory measurements and simulations of the hardware capture the second-scale electric power dynamics of heat pumps providing grid services like load shifting and load shedding. Field measurements, behavior tracking, and qualitative surveys of people in their homes over multiple years—including experimentally adjusting the heating and cooling system to provide grid services—to capture the reciprocal effect of human behavior on grid services, and grid services on human comfort. Taken together, these data capture the complete Hardware and Human in the loop system for residential heat pumps, reducing large uncertainties in simulation for design, and models for control of heat pumps, and grid-interactive buildings.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2023

Control of iodine and tellurium for use in domestic molybdenum-99 production efforts

Three initial proof-of-concept experiments were performed to test the removal of I and Te from solutions containing Mo for potential abatement during chemical processing to purify 99 Mo. All three proof-of-concept experiments produced results indicating that further optimization could provide methods for I and/or Te abatement from multiple matrices. Decamp and Happel (2013) describe the use of CL resin from Eichrom Technologies loaded with Ag + combined with Amberlite XAD-4 in the chromatographic separation of irradiated fission products in 1 M HNO 3 to separate iodine species where iodide and iodate react with Ag + and I2 adheres to the Amberlite resin. The method worked well under processing conditions in a medical isotope facility although many separation methods use higher concentrations of HNO 3 which could adversely impact the Ag + loading. The experiment performed here used a roughly 2 mL column of CL resin loaded with Ag + and Amberlite XAD-4 to separate µg quantities of I, Te, and Mo in 3 M HNO 3 .

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
NASA NTRS1979

Technical assistance for law-enforcement communications: Case study report

Methods developed to improve police communications systems are described. Use of queueing analysis shows several ways of improving time of response to inquiries made from the field for license plate checks and for information on current wants and warrants, through a state multiple switcher network. Design criteria for more efficient centralized switching equipment are developed. A message load problem experienced in a dispatch center is analyzed, showing that communications could be improved by adding communications channels, not by adding people.

Reilly, N. B.↗
NASA NTRS1994

Computational predictive methods for fracture and fatigue

The damage-tolerant design philosophy as used by aircraft industries enables aircraft components and aircraft structures to operate safely with minor damage, small cracks, and flaws. Maintenance and inspection procedures insure that damages developed during service remain below design values. When damage is found, repairs or design modifications are implemented and flight is resumed. Design and redesign guidelines, such as military specifications MIL-A-83444, have successfully reduced the incidence of damage and cracks. However, fatigue cracks continue to appear in aircraft well before the design life has expired. The F16 airplane, for instance, developed small cracks in the engine mount, wing support, bulk heads, the fuselage upper skin, the fuel shelf joints, and along the upper wings. Some cracks were found after 600 hours of the 8000 hour design service life and design modifications were required. Tests on the F16 plane showed that the design loading conditions were close to the predicted loading conditions. Improvements to analytic methods for predicting fatigue crack growth adjacent to holes, when multiple damage sites are present, and in corrosive environments would result in more cost-effective designs, fewer repairs, and fewer redesigns. The overall objective of the research described in this paper is to develop, verify, and extend the computational efficiency of analysis procedures necessary for damage tolerant design. This paper describes an elastic/plastic fracture method and an associated fatigue analysis method for damage tolerant design. Both methods are unique in that material parameters such as fracture toughness, R-curve data, and fatigue constants are not required. The methods are implemented with a general-purpose finite element package. Several proof-of-concept examples are given. With further development, the methods could be extended for analysis of multi-site damage, creep-fatigue, and corrosion fatigue problems.

Cordes, J.↗
NASA NTRS2001

A Unique Power System For The ISS Fluids And Combustion Facility

Unique power control technology has been incorporated into an electrical power control unit (EPCU) for the Fluids and Combustion Facility (FCF). The objective is to maximize science throughput by providing a flexible power system that is easily reconfigured by the science payload. Electrical power is at a premium on the International Space Station (ISS). The EPCU utilizes advanced power management techniques to maximize the power available to the FCF experiments. The EPCU architecture enables dynamic allocation of power from two ISS power channels for experiments. Because of the unique flexible remote power controller (FRPC) design, power channels can be paralleled while maintaining balanced load sharing between the channels. With an integrated and redundant architecture, the EPCU can tolerate multiple faults and still maintain FCF operation. It is important to take full advantage of the EPCU functionality. The EPCU acts as a buffer between the experimenter and the ISS power system with all its complex requirements. However, FCF science payload developers will still need to follow guidelines when designing the FCF payload power system. This is necessary to ensure power system stability, fault coordination, electromagnetic compatibility, and maximum use of available power for gathering scientific data.

Fox, David A.↗
NASA NTRS2003

Application of Circulation Control Technology to Airframe Noise Reduction

This report is a summary of the work performed by Georgia Tech Research Institute (GTRI) under NASA Langley Grant NAG-1-2146, which was awarded as a part of NASA's Breakthrough Innovative Technologies (BIT) initiative. This was a three-year program, with a one-year no-cost extension. Each year's study has been an integrated effort consisting of computational fluid dynamics, experimental aerodynamics, and detailed noise and flow measurements. Year I effort examined the feasibility of reducing airframe noise by replacing the conventional wing systems with a Circulation Control Wing (CCW), where steady blowing was used through the trailing edge of the wing over a Coanda surface. It was shown that the wing lift increases with CCW blowing and indeed for the same lift, a CCW wing was shown to produce less noise. Year 2 effort dealt with a similar study on the role of pulsed blowing on airframe noise. The main objective of this portion of the study was to assess whether pulse blowing from the trailing edge of a CCW resulted in more, less, or the same amount of radiated noise to the farfield. Results show that a reduction in farfield noise of up to 5 dB is measured when pulse flow is compared with steady flow for an equivalent lift configuration. This reduction is in the spectral region associated with the trailing edge jet noise. This result is due to the unique advantage that pulsed flow has over steady flow. For a range of frequencies, more lift is experienced with the same mass flow as the steady case. Thus, for an equivalent lift and slot height, the pulsed system can operate at lower jet velocities, and hence lower jet noise. The computational analysis showed that for a given time-averaged mass flow rate, pulsed jets give a higher value of C(sub l) and a higher L/D than equivalent steady jets. This benefit is attributable to higher instantaneous jet velocities, and higher instantaneous C(sub mu) values for the pulsed jet. Pulsed jet benefits increase at higher frequencies. However, these advantages are somewhat offset by the unsteadiness in the loads, which will cause structural vibrations and fatigue. Additional studies must be done, perhaps with multiple jets on the upper and lower surfaces, to smooth out the fluctuations in lift while retaining the benefits. The rest of the effort was devoted to examining ways of reducing flap edge noise by blowing air through a Coanda nozzle over a rounded tip of the flap. In this case, we were successful in moving the tip vortex away from the tip, but the device producing the blowing was noisy and we were unable to examine the noise benefits, although we believe that the movement of the tip vortex far from the tip should provide noise benefits. It should be noted that in an effort to understand the fluid dynamics and the aeroacoustics of a jet blowing over a Coanda surface, we also carried out a very extensive study of the high aspect ratio slot jets. A first-ever set of far-field noise spectra were measured for jets exhausting from slots with aspect ratios in the range 100 to 3000. Parallel measurements of velocity profiles, length scales and convection velocities were measured to understand the noise generation of high aspect ratio jets. Attempts were also made to develop jet noise prediction schemes for such jets. Much of the work done under this effort has been described in five conference papers and two doctoral theses. The first year s work on the use of steady blowing was described in two AIAA papers presented at the 2001 AIAA Aerospace Sciences Meeting in Reno. Subsequent work was presented at the 9th AIMCEAS Aeroacoustics Conference and Exhibit held at Hilton Head May 12-13. Another paper is to be presented at the 2004 AIAA Aerospace Sciences Meeting in Reno in January 2004. All six papers are included with this report as Appendices. The bulk of the experimental work done in an effort to produce a pulsed flow that is free of upstream noise is also attached as an Appendix.

Ahuja, K. K.↗
NASA NTRS2005

Multi-Kilowatt Power Module for High-Power Hall Thrusters

Future NASA missions will require high-performance electric propulsion systems. Hall thrusters are being developed at NASA Glenn for high-power, high-specific impulse operation. These thrusters operate at power levels up to 50 kW of power and discharge voltages in excess of 600 V. A parallel effort is being conducted to develop power electronics for these thrusters that push the technology beyond the 5kW state-of-the-art power level. A 10 kW power module was designed to produce an output of 500 V and 20 A from a nominal 100 V input. Resistive load tests revealed efficiencies in excess of 96 percent. Load current share and phase synchronization circuits were designed and tested that will allow connecting multiple modules in parallel to process higher power.

Pinero, Luis R.↗
NASA NTRS1997

Stress Intensity Factor Solutions for Multiple Edge Cracks in Ceramic Matrix Composites

NASA Lewis Research Center conducted a study to determine the stress intensity factor solutions for periodic arrays of bridged cracks for various crack spacings and crack lengths. Initially, the stress intensity factor of an array of unbridged multiple edge cracks was determined under constant global displacement as well as at a point load along the crack wake. These solutions are expected to contribute toward the development of a damage-based life-prediction methodology for CMC engine components.

Ghosn, Louis↗
NASA NTRS2008

Impacts of the IBM Cell Processor to Support Climate Models

NASA is interested in the performance and cost benefits for adapting its applications to the IBM Cell processor. However, its 256KB local memory per SPE and the new communication mechanism, make it very challenging to port an application. We selected the solar radiation component of the NASA GEOS-5 climate model, which: (1) is representative of column physics (approximately 50% computational time), (2) has a high computational load relative to transferring data from and to main memory, (3) performs independent calculations across multiple columns. We converted the baseline code (single-precision, Fortran) to C and ported it with manually SIMDizing 4 independent columns and found that a Cell with 8 SPEs can process 2274 columns per second. Compared with the baseline results, the Cell is approximately 5.2X, approximately 8.2X, approximately 15.1X faster than a core on Intel Woodcrest, Dempsey, and Itanium2, respectively. We believe this dramatic performance improvement makes a hybrid cluster with Cell and traditional nodes competitive.

Zhou, Shujia↗
NASA NTRS2004

Heat Control via Torque Control in Friction Stir Welding

In a proposed advance in friction stir welding, the torque exerted on the workpiece by the friction stir pin would be measured and controlled in an effort to measure and control the total heat input to the workpiece. The total heat input to the workpiece is an important parameter of any welding process (fusion or friction stir welding). In fusion welding, measurement and control of heat input is a difficult problem. However, in friction stir welding, the basic principle of operation affords the potential of a straightforward solution: Neglecting thermal losses through the pin and the spindle that supports it, the rate of heat input to the workpiece is the product of the torque and the speed of rotation of the friction stir weld pin and, hence, of the spindle. Therefore, if one acquires and suitably processes data on torque and rotation and controls the torque, the rotation, or both, one should be able to control the heat input into the workpiece. In conventional practice in friction stir welding, one uses feedback control of the spindle motor to maintain a constant speed of rotation. According to the proposal, one would not maintain a constant speed of rotation: Instead, one would use feedback control to maintain a constant torque and would measure the speed of rotation while allowing it to vary. The torque exerted on the workpiece would be estimated as the product of (1) the torque-multiplication ratio of the spindle belt and/or gear drive, (2) the force measured by a load cell mechanically coupled to the spindle motor, and (3) the moment arm of the load cell. Hence, the output of the load cell would be used as a feedback signal for controlling the torque (see figure).

Venable, Richard↗
NASA NTRS2013

RS-34 (Peacekeeper Post Boost Propulsion System) Orbital Debris Application Concept Study

The Advanced Concepts Office (ACO) at the NASA Marshall Space Flight Center (MSFC) lead a study to evaluate the Rocketdyne produced RS-34 propulsion system as it applies to an orbital debris removal design reference mission. The existing RS-34 propulsion system is a remaining asset from the de-commissioned United States Air Force Peacekeeper ICBM program; specifically the pressure-fed storable bi-propellant Stage IV Post Boost Propulsion System. MSFC gained experience with the RS-34 propulsion system on the successful Ares I-X flight test program flown in the Ares I-X Roll control system (RoCS). The heritage hardware proved extremely robust and reliable and sparked interest for further utilization on other potential in-space applications. Subsequently, MSFC is working closely with the USAF to obtain all the remaining RS-34 stages for re-use opportunities. Prior to pursuit of securing the hardware, MSFC commissioned the Advanced Concepts Office to understand the capability and potential applications for the RS-34 Phoenix stage as it benefits NASA, DoD, and commercial industry. Originally designed, the RS-34 Phoenix provided in-space six-degrees-of freedom operational maneuvering to deploy multiple payloads at various orbital locations. The RS-34 Concept Study, preceded by a utilization study to understand how the unique capabilities of the RS-34 Phoenix and its application to six candidate missions, sought to further understand application for an orbital debris design reference mission as the orbital debris removal mission was found to closely mimic the heritage RS-34 mission. The RS-34 Orbital Debris Application Concept Study sought to identify multiple configurations varying the degree of modification to trade for dry mass optimization and propellant load for overall capability and evaluation of several candidate missions. The results of the RS-34 Phoenix Utilization Study show that the system is technically sufficient to successfully support all of the missions analyzed. The results and benefits of the RS-34 Orbital Debris Application Concept Study are presented in this paper.

Esther, Elizabeth A.↗
NASA NTRS2015

NASA CPAS Drogue Textile Riser Feasibility Study

Steel cable was chosen for the lower end of the drogue and main parachute risers on NASA's Orion Multi Purpose Crew Vehicle Parachute Assembly System (CPAS) to protect the risers from extreme temperatures and abrasion should they contact the crew module during deployment, as was done for Apollo. Due to the weight and deployment complexity inherent in steel, there was significant interest in the possibility of substituting textile for steel for the drogue and main parachute risers. However, textile risers could be damaged when subjected to high temperature and abrasion. Investigations were consequently performed by a subset of the authors to determine whether sacrificial, non-load-bearing textile riser covers could be developed to mitigate the thermal and abrasion concerns. Multiple material combinations were tested, resulting in a cover design capable of protecting the riser against severe riser/crew module contact interactions. A feasibility study was then conducted to evaluate the performance of the textile drogue riser cover in relevant abrasive environments. This paper describes the testing performed and documents the results of this feasibility study.

Hennings, Elsa J.↗
NASA NTRS2018

The SPACE Computer Code for Analyzing the International Space Station Electrical Power System: Past, Present, and Future

The System Power Analysis for Capability Evaluation (SPACE) computer code was initially developed by NASA in 1988 to assess the Space Station Freedom electric power system and later adapted to support contractor electrical power system capability analyses for the International Space Station (ISS). Over time, the code has supported many efforts such as ISS redesign activities in the early 1990s, assessment of time-phased loads against power system operating limits for future ISS assembly flights (including Certification of Flight Readiness reviews by the ISS program office), and determining the optimum solar array gimbal positions while respecting keep-out zones which minimize both solar array contamination and structural loads. The code has been validated by comparisons with ISS on-orbit data in multiple validation episodes. Recent updates to the code include the incorporation of a Lithium-Ion battery model in addition to the Nickel Hydrogen battery model and modifications to the solar array degradation model to better match on-orbit test results. SPACE has also been extended beyond the ISS to include modeling of the Orion Multi-Purpose Crew Vehicle electrical power system (SPACE-MPCV) and Mars Surface Electrical Power Systems (MSEPS). Portions of SPACE were integrated with a trajectory code to form a Solar Electric Propulsion Simulation (SEPSim), which can be used for analyzing solar electric propulsion missions. In addition, SPACE methods and subroutines have been adapted to a multitude of other projects. This paper summarizes the initial code development and subsequent code utilization in the context of the overall ISS program development and on-orbit operations. Recent updates and results from the code are discussed, including preliminary analyses for the Orion power system.

Electrical Power System↗
NASA NTRS2019

Propeller-Wing Integration on the Parallel Electric-Gas Architecture with Synergistic Utilization Scheme (PEGASUS) Aircraft

Electrically powered aircraft show promise for reducing emissions and energy consumption, but many of the opportunities surrounding electric propulsion have yet to be explored. One opportunity is the use of multiple propulsors or distributed propulsion for improved propulsion airframe integration. However, the size, power, location, and optimum number of propulsors has not been thoroughly vetted. This paper describes the use of FlightStream, a surface vorticity solver, to investigate the aerodynamic-propulsion integration of four propulsors across the leading edge of a wing, two inboard and two at the wingtips, as proposed in the NASA Parallel Electric-Gas Architecture with Synergistic Utilization Scheme (PEGASUS) concept. FlightStream was used to determine the minimum power required for cruise for the PEGASUS aircraft. The study found that tip propellers are effective at lowering both viscous and induced drag when compared to inboard propellers alone or inboard propellers combined with tip propellers. Despite this drag savings, the propulsive efficiency was reduced when a single propeller class was used, resulting in a higher system power consumption when compared with using multiple propeller classes. Reductions in propeller efficiency are related to increases in disc and blade loading of the propeller; thus, larger propellers or higher tip speeds are seen as possible means of to improve system performance.

Blaesser, Nathaniel J.↗
DOE OSTI2023

Investigating Multi-Microgrid Black Start Methods Using Grid-Forming Inverters: Preprint

This paper examines state-of-the-art microgrid (MG) black-start technologies with high IBR penetrations and proposes black-start and interconnection methods for 100% grid-forming (GFM) inverter-based MGs. A multiple-microgrid approach is proposed and compared to the existing methods in a 4-bus, 12-GFM inverter simulation test setup. This investigation involves intelligent synchronization units called "synchrobreakers," which enable the synchronization of multiple MGs based on their terminal measurements. MGs in this setup are held at different loading levels and comprise averaged models of GFM inverters with ideal voltage sources. The results of the black-start techniques are compared, and conclusions are drawn to better prepare MG planners and DSOs for the next-generation GFM inverter-based multi-MG black-start procedures.

black start↗