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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Coordinated Fault Tolerance for High-Performance Computing

Our work to meet our goal of end-to-end fault tolerance has focused on two areas: (1) improving fault tolerance in various software currently available and widely used throughout the HEC domain and (2) using fault information exchange and coordination to achieve holistic, systemwide fault tolerance and understanding how to design and implement interfaces for integrating fault tolerance features for multiple layers of the software stack—from the application, math libraries, and programming language runtime to other common system software such as jobs schedulers, resource managers, and monitoring tools.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS1972

4-D guidance system design with application to STOL air traffic control.

A new guidance technique, referred to as 4-D guidance, is being developed to improve the operation of future STOL aircraft transportation systems. 4-D guidance refers to a technique of synthesizing a complex three-dimensional flight path from simple pilot inputs and flying the aircraft along the path according to an ATC specified time schedule. The two major elements of a 4-D guidance system are the trajectory synthesizer and the control law for flying the aircraft along the synthesized trajectory using the aircraft's autopilot and autothrottle. Inputs to the trajectory synthesizer are the three-dimensional coordinates of waypoints, the turning radius, the speed range, the acceleration limits and the arrival time at time control waypoints. First the three-dimensional trajectory is computed using circular arcs and straight lines. Then the airspeed profile, compensated for wind, is calculated to achieve the desired arrival times. The pilot is informed if the arrival times cannot be achieved. The synthesized trajectory is stored as a time sequence of reference states and controls which the aircraft is forced to track using a linear feedback law.

Erzberger, H.↗
NASA NTRS2000

NASA Goddard Space Flight Center

The NASA SLR Operational Center is responsible for: 1) NASA SLR network control, sustaining engineering, and logistics; 2) ILRS mission operations; and 3) ILRS and NASA SLR data operations. NASA SLR network control and sustaining engineering tasks include technical support, daily system performance monitoring, system scheduling, operator training, station status reporting, system relocation, logistics and support of the ILRS Networks and Engineering Working Group. These activities ensure the NASA SLR systems are meeting ILRS and NASA mission support requirements. ILRS mission operations tasks include mission planning, mission analysis, mission coordination, development of mission support plans, and support of the ILRS Missions Working Group. These activities ensure than new mission and campaign requirements are coordinated with the ILRS. Global Normal Points (NP) data, NASA SLR FullRate (FR) data, and satellite predictions are managed as part of data operations. Part of this operation includes supporting the ILRS Data Formats and Procedures Working Group. Global NP data operations consist of receipt, format and data integrity verification, archiving and merging. This activity culminates in the daily electronic transmission of NP files to the CDDIS. Currently of all these functions are automated. However, to ensure the timely and accurate flow of data, regular monitoring and maintenance of the operational software systems, computer systems and computer networking are performed. Tracking statistics between the stations and the data centers are compared periodically to eliminate lost data. Future activities in this area include sub-daily (i.e., hourly) NP data management, more stringent data integrity tests, and automatic station notification of format and data integrity issues.

Carter, David↗
NASA NTRS2012

A Proposed Strategy for the U.S. to Develop and Maintain a Mainstream Capability Suite ("Warehouse") for Automated/Autonomous Rendezvous and Docking in Low Earth Orbit and Beyond

The ability of space assets to rendezvous and dock/capture/berth is a fundamental enabler for numerous classes of NASA fs missions, and is therefore an essential capability for the future of NASA. Mission classes include: ISS crew rotation, crewed exploration beyond low-Earth-orbit (LEO), on-orbit assembly, ISS cargo supply, crewed satellite servicing, robotic satellite servicing / debris mitigation, robotic sample return, and robotic small body (e.g. near-Earth object, NEO) proximity operations. For a variety of reasons to be described, NASA programs requiring Automated/Autonomous Rendezvous and Docking/Capture/Berthing (AR&D) capabilities are currently spending an order-of-magnitude more than necessary and taking twice as long as necessary to achieve their AR&D capability, "reinventing the wheel" for each program, and have fallen behind all of our foreign counterparts in AR&D technology (especially autonomy) in the process. To ensure future missions' reliability and crew safety (when applicable), to achieve the noted cost and schedule savings by eliminate costs of continually "reinventing the wheel ", the NASA AR&D Community of Practice (CoP) recommends NASA develop an AR&D Warehouse, detailed herein, which does not exist today. The term "warehouse" is used herein to refer to a toolbox or capability suite that has pre-integrated selectable supply-chain hardware and reusable software components that are considered ready-to-fly, low-risk, reliable, versatile, scalable, cost-effective, architecture and destination independent, that can be confidently utilized operationally on human spaceflight and robotic vehicles over a variety of mission classes and design reference missions, especially beyond LEO. The CoP also believes that it is imperative that NASA coordinate and integrate all current and proposed technology development activities into a cohesive cross-Agency strategy to produce and utilize this AR&D warehouse. An initial estimate indicates that if NASA strategically coordinates the development of a robust AR&D capability across the Agency, the cost of implementing AR&D on a spacecraft could be reduced from roughly $70M per mission to as low as $7M per mission, and the associated development time could be reduced from 4 years to 2 years, after the warehouse is completely developed. Table 1 shows the clear long-term benefits to the Agency in term of costs and schedules for various missions. (The methods used to arrive at the Table 1 numbers is presented in Appendices A and B.)

Krishnakumar, Kalmanje S.↗
NASA NTRS2010

Plans for the Meter Class Autonomous Telescope and Potential Coordinated Measurements with Kwajalein Radars

The National Aeronautics and Space Administration's (NASA) Orbital Debris Program Office is teaming with the US Air Force Research Laboratory's (AFRL) Maui Optical Site to deploy a moderate field-of-view, 1.3 m aperture, optical telescope for orbital debris applications. The telescope will be located on the island of Legan in the Kwajalein Atoll and is scheduled for completion in the Spring of 2011. The telescope is intended to sample both low inclination/high eccentricity orbits and near geosynchronous orbits. The telescope will have a 1 deg diagonal field-of-view on a 4K x 4K CCD. The telescope is expected to be able to detect 10-cm diameter debris at geosynchronous altitudes (5 sec exposure assuming a spherical specular phase function w/ albedo =0.13). Once operational, the telescope has the potential of conducting simultaneous observations with radars operated by the US Army at Kwajalein Atoll (USAKA) and located on the island of Roi-Namur, approximately 55 km to the north of Legan. Four radars, representing 6 frequency bands, are available for use: ALTAIR (ARPA-Long Range Tracking and Instrumentation Radar) operating at VHF & UHF, TRADEX (Target Resolution and Discrimination Experiment) operating at L-band and S-band, ALCOR (ARPA-Lincoln C-band Observables Radar) operating at S-band, and MMW (Millimeter Wave) Radar operating at Ka-band. Also potentially available is the X-band GBRP (Ground Based Radar-Prototype located 25 km to the southeast of Legan on the main island of Kwajalein.

Stansberry, Gene↗
NASA NTRS1987

Results of using the global positioning system to maintain the time and frequency synchronization in the Deep Space Network

There are two hydrogen maser clocks located at each signal processing center (SPC) in the DSN. Close coordination of the time and frequency of the SPC clocks is needed to navigate spacecraft to the outer planets. A recent example was the Voyager spacecraft's encounter with Uranus in January 1986. The clocks were adjusted with the goal of minimizing time and frequency offsets between the SPCs at encounter. How time and frequency at each SPC is estimated using data acquired from the Global Positioning System Timing Receivers operating on the NBS-BIH (National Bureau of Standards-Bureau International de l'Heure) tracking schedule is described. These data are combined with other available timing receiver data to calculate the time offset estimates. The adjustment of the clocks is described. It was determined that long range hydrogen maser drift is quite predictable and adjustable within limits. This enables one to minimize time and frequency differences between the three SPCs for many months by matching the drift rates of the three standards. Data acquisition and processing techniques using a Kalman filter to make estimates of time and frequency offsets between the clocks at the SPCs and UTC(NBS) (Coordinated Universal Time realized at NBS) are described.

Clements, P. A.↗
NASA NTRS1993

A typical pointed observation in IRAS designed to fit into a 15 minute window

A typical pointed observation in the Infrared Astronomical Satellite (IRAS) was designed to fit into a 15 minute window. Observing constraints, however, did not always permit targets from the scientific program to be observed on exactly 15 minute centers and a few months into the mission it was realized that the automatic scheduling program left times when no observations were being made. In order to use this potentially wasted observing time, a mode of pointed observations, the 'filler' mode, with shorter observation duration was initiated. Locations were picked on an arbitrary grid, spaced relatively uniformly in ecliptic coordinates, and the telescope was pointed to one of these sites whenever a gap potentially occurred. One of us (GXN) was the coordinator of this effort (the FL sub-group). There are a total of 22 FL fields, 13 of which have more than 50 component observations. These 13 fields cover about 30 square degrees. It was proposed to concentrate on one filler field, FL29, a field with 53 coverages which thus had among the deepest coverage of those observed in this mode. This field was also observed extensively at various non-infrared wavelengths by a variety of techniques. Because the IRAS observations of FL29 were made at the limits of the survey sensitivity and at different twist angles it was necessary to make significant technical advances in the methods used in the processing and analyzing the data. In particular, if normal IRAS coaddition procedures were used, the noise resulting from coaddition of the multiple frames did not decrease in the manner expected once significantly different twist angles were included in the coaddition. The technical effort needed to reduce the observations of FL29 was completed and now the noise behavior is understood and well behaved. The reduction of the field FL29 observations is done.

Neugebauer, G.↗
NASA NTRS2011

Role of the Controller in an Integrated Pilot-Controller Study for Parallel Approaches

Closely spaced parallel runway operations have been found to increase capacity within the National Airspace System but poor visibility conditions reduce the use of these operations [1]. Previous research examined the concepts and procedures related to parallel runways [2][4][5]. However, there has been no investigation of the procedures associated with the strategic and tactical pairing of aircraft for these operations. This study developed and examined the pilot s and controller s procedures and information requirements for creating aircraft pairs for closely spaced parallel runway operations. The goal was to achieve aircraft pairing with a temporal separation of 15s (+/- 10s error) at a coupling point that was 12 nmi from the runway threshold. In this paper, the role of the controller, as examined in an integrated study of controllers and pilots, is presented. The controllers utilized a pairing scheduler and new pairing interfaces to help create and maintain aircraft pairs, in a high-fidelity, human-in-the loop simulation experiment. Results show that the controllers worked as a team to achieve pairing between aircraft and the level of inter-controller coordination increased when the aircraft in the pair belonged to different sectors. Controller feedback did not reveal over reliance on the automation nor complacency with the pairing automation or pairing procedures.

Verma, Savvy↗
DOE OSTI2012

Lessons Learned from a Complex FUSRAP Site - Sylvania Corning FUSRAP Site - 12269

Since its addition to the Formerly Utilized Sites Remedial Action Program (FUSRAP) in 2005, the Sylvania Corning FUSRAP Site (the Site) in Hicksville, New York, has provided challenges and opportunities from which to gain lessons learned for conducting investigation work at a complex multi-contaminant FUSRAP Site. The United States Army Corps of Engineers (USACE) and its contractors conducted a Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) Remedial Investigation (RI) and are currently in the Feasibility Study (FS) phase at the Site. This paper presents the planning, execution, and reporting lessons learned by USACE during the RI/FS. The Site, operated from 1952 to 1967 for the research, development, and fabrication of nuclear elements under the Atomic Energy Commission, and other government and commercial contracts. Previous investigations performed by the New York State Department of Environmental Conservation (NYSDEC) and the current property owner have identified uranium, thorium, nickel, and chlorinated solvents, as Site contaminants [1]. The property owner is currently under two separate voluntary agreements with NYSDEC to investigate and remediate the Site. USACE's work at the site has been independent of this voluntary agreement and has moved on a parallel path with any work the property owner has completed. The project at the Site is complex because of the radiological and chemical concerns in both soils and groundwater, high hydraulically conductive soils, lack of a shallow aquiclude/aquitard, and a principal water table aquifer underlying the site. Contaminants are migrating from the Site and may potentially impact local drinking water supplies (municipal wells). During the RI/FS process the project team has encountered many issues and has thus developed many resolutions. The issues are organized into three categories: Planning and Contracting, Execution, and Reporting. Planning and Contracting lessons learned include: how to incorporate an overwhelming volume of historical data; how to manage a complex team of three prime contractors innovatively, and how to implement a project under an Award Fee task order. Execution lessons learned include: characterization of investigation derived wastes, and proper approach to radiological scanning of direct-push borings and soil cores. Reporting lessons learned include: coordinating multiple phase (iterative) reporting, large dataset presentation, and the National Priorities List (NPL) designation. The goal of this paper is to provide a resource for other project delivery teams that encounter similar situations on their projects to optimize cost savings, realization of efficiency, shorten schedules, or simply ensure higher quality deliverables. Each FUSRAP project is unique but there are many lessons we can apply to each site to gain efficiency and work more effectively. The Sylvania Corning FUSRAP site is a complex site with both soils and groundwater contamination, contamination to depths of 182 meters, and a highly politically charged environment of PRP involvement. Many of the lessons the project team has learned during the life of the project to date are being shared with others as well as being applied back to this project for future work. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2010

Analyzing of Balancing Authorities Cooperation Methods with High Variable Generation Penetration

With the rapidly growing penetration level of wind and solar generation, the challenges of managing variability and the uncertainty of intermittent renewable generation become more and more significant. The problem of power variability and uncertainty gets exacerbated when each balancing authority (BA) works locally and separately to balance its own subsystem. The virtual BA concept is based on various forms of collaboration between individual BAs to manage power variability and uncertainty. The virtual BA will have a wide area control capability in managing its operational balancing requirements in different time frames. This coordination results in the improvement of efficiency and reliability of power system operation while facilitating the high level integration of green, intermittent energy resources. Several strategies for virtual BA implementation, such as Area Control Error (ACE) diversity interchange (ADI), variable generation only BA, BA consolidation, dynamic scheduling, and regulation and load following sharing are discussed in this paper. The objective of such strategies is to allow individual BAs within a large power grid to help each other dealing with power variability. Innovative methods have been developed to simulate the balancing operation of BAs. These methods evaluate the BA operation through a number of metrics such as capacity, ramp rate, ramp duration, energy and cycling requirements to evaluate the performance of different virtual BA strategies.

17 WIND ENERGY↗
NASA NTRS2016

Methods for Determining Aircraft Surface State at Lesser-Equipped Airports

Tactical departure scheduling within a terminal airspace must accommodate a wide spectrum of surveillance and communication capabilities at multiple airports. The success of such a scheduler is highly dependent upon the knowledge of a departure's state while it is still on the surface. Airports within a common Terminal RAdar CONtrol (TRACON) airspace possess varying levels of surface surveillance infrastructure which directly impacts uncertainties in wheels-off times. Large airports have access to surface surveillance data, which is shared with the TRACON, while lesser-equipped airports still rely solely on controllers in Air Traffic Control Towers (Towers). Coordination between TRACON and Towers can be greatly enhanced when the TRACON controller has access to the surface surveillance and the associated decision-support tools at well-equipped airports. Similar coordination at lesser-equipped airports is still based on verbal communications. This paper investigates possible methods to reduce the uncertainty in wheels-off time predictions at the lesser-equipped airports through the novel use of Over-the-Air (OTA) data transmissions. We also discuss the methods and equipment used to collect sample data at lesser-equipped airports within a large US TRACON, as well as the data evaluation to determine if meaningful information can be extracted from it.

departure scheduling↗
DOE OSTI2021

Deep Reinforcement Learning Enabled Physical-Model-Free Two-Timescale Voltage Control Method for Active Distribution Systems

Active distribution networks are being challenged by frequent and rapid voltage violations due to renewable energy integration. Conventional model-based voltage control methods rely on accurate parameters of the distribution networks, which are difficult to achieve in practice. This paper proposes a novel physical-model-free two-timescale voltage control framework for active distribution systems. To achieve fast control of PV inverters, the whole network is first partitioned into several subnetworks using voltage-reactive power sensitivity. Then, the scheduling of PV inverters in the multiple sub-networks is formulated as Markov games and solved by a multi-agent soft actor-critic (MASAC) algorithm, where each subnetwork is modeled as an intelligent agent. All agents are trained in a centralized manner to learn a coordinated strategy while being executed based on only local information for fast response. For the slower time-scale control, OLTCs and switched capacitors are coordinated by a single agent-based SAC algorithm using the global information with considering control behaviors of the inverters. Particularly, the two-level agents are trained concurrently with information exchange according to the reward signal calculated from the data-driven surrogate model. Comparative tests with different benchmark methods on IEEE 33-and 123-bus systems and 342-node low voltage distribution system demonstrate that the proposed method can effectively mitigate the fast voltage violations and achieve systematical coordination of different voltage regulation assets without the knowledge of accurate system model.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2013

Final Harvest of Above-Ground Biomass and Allometric Analysis of the Aspen FACE Experiment

The Aspen FACE experiment, located at the US Forest Service Harshaw Research Facility in Oneida County, Wisconsin, exposes the intact canopies of model trembling aspen forests to increased concentrations of atmospheric CO 2 and O 3 . The first full year of treatments was 1998 and final year of elevated CO 2 and O 3 treatments is scheduled for 2009. This proposal is to conduct an intensive, analytical harvest of the above-ground parts of 24 trees from each of the 12, 30 m diameter treatment plots (total of 288 trees) during June, July & August 2009. This above-ground harvest will be carefully coordinated with the below-ground harvest proposed by D.F. Karnosky et al. (2008 proposal to DOE). We propose to dissect harvested trees according to annual height growth increment and organ (main stem, branch orders, and leaves) for calculation of above-ground biomass production and allometric comparisons among aspen clones, species, and treatments. Additionally, we will collect fine root samples for DNA fingerprinting to quantify biomass production of individual aspen clones. This work will produce a thorough characterization of above-ground tree and stand growth and allocation above ground, and, in conjunction with the below ground harvest, total tree and stand biomass production, allocation, and allometry.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS2008

The Project Manager Who Saved His Country

George Meade defeated Robert E. Lee, one of the greatest military leaders of all time. How did he do it? By using the skills he had learned as a project manager and outperforming Lee in all aspects of project management. Most project managers are familiar with the Project Management Institute's "Guide to the Project Management Body of Knowledge" (PMBOK), which identifies the skills and knowledge crucial to successful project management. Project managers need to make sure that all the elements of a project work together. They must develop and execute plans and coordinate changes to those plans. A project manager must define the scope of the work, break it into manageable pieces, verify and control what work is being done, and make sure that the work being done is essential to the project. Every project manager knows the challenges of schedule and the value of schedule slack. Project managers must get the resources they need and use them effectively. Project managers get the people they need and use their talents to achieve mission success. Projects generate huge amounts of information. A key to project success is getting sufficient and accurate information to the people who need it when they need it. Project managers must identify and quantify the risks that jeopardize project success and make plans for dealing with them. Studying Meade and Lee's performances at Gettysburg can help modern project managers appreciate, develop, and use the skills they need to be good project managers. The circumstances may be different, but the basic principles are the same. This dramatic event in American history shows how the skills of project management can be used in almost any situation. Former project manager George Meade used those skills to change the tide of the Civil War.

Baniszewski, John↗
DOE OSTI2022

Robust Scheduling of Networked Microgrids for Economics and Resilience Improvement

The benefits of networked microgrids in terms of economics and resilience are investigated and validated in this work. Considering the stochastic unintentional islanding conditions and conventional forecast errors of both renewable generation and loads, a two-stage adaptive robust optimization is proposed to minimize the total operating cost of networked microgrids in the worst scenario of the modeled uncertainties. By coordinating the dispatch of distributed energy resources (DERs) and responsive demand among networked microgrids, the total operating cost is minimized, which includes the start-up and shut-down cost of distributed generators (DGs), the operation and maintenance (O&M) cost of DGs, the cost of buying/selling power from/to the utility grid, the degradation cost of energy storage systems (ESSs), and the cost associated with load shedding. The proposed optimization is solved with the column and constraint generation (C&CG) algorithm. The results of case studies demonstrate the advantages of networked microgrids over independent microgrids in terms of reducing total operating cost and improving the resilience of power supply.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2024

Synthesis of Correct Digital Controller Models from Specifications by Model Transformation (21-0320)

The design of high consequence controllers (in weapons systems, autonomy, etc.) that do what they are supposed to do is a significant challenge. Testing simply does not come close to meeting the requirements for assurance. Today circuit designers at Sandia (and elsewhere) typically capture the core behavior of their components using state models in tools such as STATEFLOW. They then check that their models meet certain requirements (e.g. “The system bus must not deadlock” or “both traffic lights at an intersection must not be green at the same time”) using tools called model checkers. If the model checker returns “yes” then the property is guaranteed to be satisfied by the model. However, there are several drawbacks to this industry practice: (1) there is a lot of detail to get right, this is particularly challenging when there are multiple components requiring complex coordination (2) any errors returned by the model checker have to be traced back through the design and fixed, necessitating rework, (3) there are severe scalability problems with this approach, particularly when dealing with concurrency. All this places high demands on the designers who now face not only an accelerated schedule but also controllers of increasing complexity. This report describes a new and fundamentally different approach to the construction of safety-critical digital controllers. Instead of directly constructing a complete model and then trying to verify it, the designer can start with an initial abstract (think “sketch”) model plus the requirements, from which a correct concrete model is automatically synthesized. There is no need for post-hoc verification of required functional properties. Having tool to carry this out will significantly impact the nation’s ability to ensure the safety of high-consequence digital systems. The approach has been implemented in a prototype tool, along with a suite of examples, including ones that reflect actual problems faced by designers. Our approach operates on a variant of Statecharts developed at Sandia called Qspecs. Statecharts are a widely used formalism for developing concurrent reactive systems, supporting scalability through allowing state models containing composite states, which are the serial or parallel composition of substates which can themselves contain statecharts. Statecharts enable an incremental style of development, in which states are progressively refined to incorporate greater detail in an incremental model of software development. Our approach formulates a set of constraints from the structure of the models and the requirements and propagates these constraints to a fixpoint. The solution to the constraints is an inductive invariant along with guards on the transitions. We also show how our approach extends to implementation refinement, decomposition, composition, and elaboration. We currently handle safety requirements written in LTL (Linear Temporal Logic)

42 ENGINEERING↗