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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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Observations and Lessons Learned from Testing of the Hanford Waste Treatment Plant Standard High Solids Vessel Design - 18635

The Hanford Waste Treatment and Immobilization Plant (WTP) recently completed qualification testing of the mixing system for the standard high solids vessel design the U.S. Department of Energy (DOE) proposed to replace several vessels in the design of the plant Pretreatment Facility. Testing was split into two phases. The first phase exercised the pulse jet mixer control system to ensure that the control software could accommodate fluids across the complete range of expected densities and viscosities within the vessel for all operational modes. The second phase of testing was focused on the mixing performance of the vessel, specifically, whether mixing was adequate to support the transfer, de-inventory, throughput, and sampling functions of the vessel. Key observations and lessons learned from testing include: - Successful transfer of waste within and beyond the design basis slurry solids concentration; - Successful resuspension and transfer of large, heavy particles; - Effective performance of multi-level bubblers for process control and monitoring; - Effective controls performance; - Reduction of sparger flowrate from nominal design flow; - Liquid blending within about 15 minutes; - Insights into sample representativeness and uniformity of transfers to inform process control strategies. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2021

The Marine and Hydrokinetic ToolKit (MHKiT) for Data Quality Control and Analysis [Slides]

The ability to collect, ingest, condition, reduce, quality control, process, visualize, and store data in a standardized way is critical at all stages of Marine Energy (ME) research and technology/project development. MHKiT is an open-source, standardized suite of ME data processing functions that provides the ability to ingest, condition, reduce, quality control, process, visualize and store ME data. MHKiT is developed in both Python and Matlab.

16 TIDAL AND WAVE POWER↗
DOE OSTI2017

Nonlinear model predictive control for chemical looping process

A control system for optimizing a chemical looping ("CL") plant includes a reduced order mathematical model ("ROM") that is designed by eliminating mathematical terms that have minimal effect on the outcome. A non-linear optimizer provides various inputs to the ROM and monitors the outputs to determine the optimum inputs that are then provided to the CL plant. An estimator estimates the values of various internal state variables of the CL plant. The system has one structure adapted to control a CL plant that only provides pressure measurements in the CL loops A and B, a second structure adapted to a CL plant that provides pressure measurements and solid levels in both loops A, and B, and a third structure adapted to control a CL plant that provides full information on internal state variables. A final structure provides a neural network NMPC controller to control operation of loops A and B.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS1972

Progress in electrochemical storage for battery systems

Efforts to improve electrochemical systems for space use relate to: (1) improvement of conventional systems; (2) development of fuel cells to practical power systems; and (3) a search for new systems that provide gains in energy density but offer comparable life and performance as conventional systems. Improvements in sealed conventional systems resulted in the areas of materials, charge control methods, cell operations and battery control, and specific process controls required during cell manufacture. Fuel-cell systems have been developed for spacecraft but the use of these power plants is limited. For present and planned flights, nickel-cadmium, silver-zinc, and silver-cadmium systems will be used. Improvements in nickel-cadmium batteries have been applied in medical and commercial areas.

Ford, F. E.↗
NASA NTRS1987

Fed-batch control based upon the measurement of intracellular NADH

A series of experiments demonstrating that on-line measurements of intracellular NADH by culture fluorescence can be used to monitor and control the fermentation process are described. A distinct advantage of intercellular NADH measurements over other monitoring techniques such as pH and dissolved oxygen is that it directly measures real time events occurring within the cell rather than changes in the environment. When coupled with other measurement parameters, it can provide a finer degree of sophistication in process control.

Armiger, W. B.↗
NASA NTRS1990

Chemical reaction of atomic oxygen with evaporated films of copper, part 4

Evaporated copper films were exposed to an atomic oxygen flux of 1.4 x 10(exp 17) atoms/sq cm per sec at temperatures in the range 285 to 375 F (140 to 191 C) for time intervals between 2 and 50 minutes. Rutherford backscattering spectroscopy (RBS) was used to determine the thickness of the oxide layers formed and the ratio of the number of copper to oxygen atoms in the layers. Oxide film thicknesses ranged from 50 to 3000 A (0.005 to 0.3 microns, or equivalently, 5 x 10(exp -9) to 3 x 10(exp -7); it was determined that the primary oxide phase was Cu2O. The growth law was found to be parabolic (L(t) varies as t(exp 1/2)), in which the oxide thickness L(t) increases as the square root of the exposure time t. The analysis of the data is consistent with either of the two parabolic growth laws. (The thin-film parabolic growth law is based on the assumption that the process is diffusion controlled, with the space charge within the growing oxide layer being negligible. The thick-film parabolic growth law is also based on a diffusion controlled process, but space-charge neutrality prevails locally within very thick oxides.) In the absence of a voltage measurement across the growing oxide, a distinction between the two mechanisms cannot be made, nor can growth by the diffusion of neutral atomic oxygen be entirely ruled out. The activation energy for the reaction is on the order of 1.1 eV (1.76 x 10(exp -19) joule, or equivalently, 25.3 kcal/mole).

Fromhold, A. T.↗
NASA NTRS1993

Fundamental rocket injector/spray programs at the Phillips Laboratory

The performance and stability of liquid rocket engines is determined to a large degree by atomization, mixing, and combustion processes. Control over these processes is exerted through the design of the injector. Injectors in liquid rocket engines are called upon to perform many functions. They must first of all mix the propellants to provide suitable performance in the shortest possible length. For main injectors, this is driven by the tradeoff between the combustion chamber performance, stability, efficiency, and its weight and cost. In gas generators and preburners, however, it is also driven by the possibility of damage to downstream components, for example piping and turbine blades. This can occur if unburned fuel and oxidant later react to create hot spots. Weight and cost considerations require that the injector design be simple and lightweight. For reusable engines, the injectors must also be durable and easily maintained. Suitable atomization and mixing must be produced with as small a pressure drop as possible, so that the size and weight of pressure vessels and turbomachinery can be minimized. However, the pressure drop must not be so small as to promote feed system coupled instabilities. Another important function of the injectors is to ensure that the injector face plate and the chamber and nozzle walls are not damaged. Typically this requires reducing the heat transfer to an acceptable level and also keeping unburned oxygen from chemically attacking the walls, particularly in reusable engines. Therefore the mixing distribution is often tailored to be fuel-rich near the walls. Wall heat transfer can become catastrophically damaging in the presence of acoustic instabilities, so the injector must prevent these from occurring at all costs. In addition to acoustic stability (but coupled with it), injectors must also be kinetically stable. That is, the flame itself must maintain ignition in the combustion chamber. This is not typically a problem with main injectors, but can be a consideration in preburners, where the desire to keep turbine inlet temperatures as cool as possible can make it advantageous for the preburners to operate as far from stoichiometry as can be tolerated. For some missions such as single stage to orbit, all of the above requirements must be maintained over a throttleable range, for example 5:1 to 10:1. Finally, the injectors must be ignitable during startup where pressures and temperatures are far from design conditions, and ignition transients must be minimized in order to avoid damage to engine components. In order to satisfy these various constraints, the injector designer must be able to perform design tradeoff studies, and it is important that this be done with minimal time and costs. In fact, it can easily be argued that reducing engine development time and costs is essential to maintaining U.S. competitiveness in space. The Propulsion Directorate of the Phillips Laboratory has invested in a number of programs to advance liquid rocket engine technology, and several of these are directed at improving design tools for liquid rocket injectors. The purpose of the presentation will be to describe some of these latter programs.

Talley, D. G.↗
NASA NTRS2016

B33C-0612: Evaluation of Simulated Biospheric Carbon Dioxide Fluxes and Atmospheric Concentrations Using Global in Situ Observations

Atmospheric mixing ratios of carbon dioxide (CO2) are largely controlled by anthropogenic emission sources and biospheric sources/sinks. Global biospheric fluxes of CO2 are controlled by complex processes facilitating the exchange of carbon between terrestrial ecosystems and the atmosphere. These processes which play a key role in these terrestrial ecosystem-atmosphere carbon exchanges are currently not fully understood, resulting in large uncertainties in the quantification of biospheric CO2 fluxes. Current models with these inherent deficiencies have difficulties simulating the global carbon cycle with high accuracy. We are developing a new modeling platform, GEOS-Chem-CASA by integrating the year-specific NASA-CASA (National Aeronautics and Space Administration - Carnegie Ames Stanford Approach) biosphere model with the GEOS-Chem (Goddard Earth Observation System-Chemistry) chemical transport model to improve the simulation of atmosphere-terrestrial ecosystem carbon exchange. We use NASA-CASA to explicitly represent the exchange of CO2 between terrestrial ecosystem and atmosphere by replacing the baseline GEOS-Chem land net CO2 flux and forest biomass burning CO2 emissions. We will present the estimation and evaluation of these "bottom-up" land CO2 fluxes, simulated atmospheric mixing ratios, and forest disturbance changes over the last decade. In addition, we will present our initial comparison of atmospheric column-mean dry air mole fraction of CO2 predicted by the model and those retrieved from NASA's OCO-2 (Orbiting Carbon Observatory-2) satellite instrument and model-predicted surface CO2 mixing ratios with global in situ observations. This evaluation is the first step necessary for our future work planned to constrain the estimates of biospheric carbon fluxes through "top-down" inverse modeling, which will improve our understanding of the processes controlling atmosphere-terrestrial ecosystem greenhouse gas exchanges, especially over regions which lack in situ observations.

in situ observations↗
DOE OSTI2016

TU-FG-201-09: Predicting Accelerator Dysfunction

Purpose: To develop an integrated statistical process control (SPC) framework using digital performance and component data accumulated within the accelerator system that can detect dysfunction prior to unscheduled downtime. Methods: Seven digital accelerators were monitored for twelve to 18 months. The accelerators were operated in a ‘run to failure mode’ with the individual institutions determining when service would be initiated. Institutions were required to submit detailed service reports. Trajectory and text log files resulting from a robust daily VMAT QA delivery were decoded and evaluated using Individual and Moving Range (I/MR) control charts. The SPC evaluation was presented in a customized dashboard interface that allows the user to review 525 monitored parameters (480 MLC parameters). Chart limits were calculated using a hybrid technique that includes the standard SPC 3σ limits and an empirical factor based on the parameter/system specification. The individual (I) grand mean values and control limit ranges of the I/MR charts of all accelerators were compared using statistical (ranked analysis of variance (ANOVA)) and graphical analyses to determine consistency of operating parameters. Results: When an alarm or warning was directly connected to field service, process control charts predicted dysfunction consistently on beam generation related parameters (BGP)– RF Driver Voltage, Gun Grid Voltage, and Forward Power (W); beam uniformity parameters – angle and position steering coil currents; and Gantry position accuracy parameter: cross correlation max-value. Control charts for individual MLC – cross correlation max-value/position detected 50% to 60% of MLCs serviced prior to dysfunction or failure. In general, non-random changes were detected 5 to 80 days prior to a service intervention. The ANOVA comparison of BGP determined that each accelerator parameter operated at a distinct value. Conclusion: The SPC framework shows promise. Long term monitoring coordinated with service will be required to definitively determine the effectiveness of the model. Varian Medical System, Inc. provided funding in support of the research presented.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

Maintenance Plan for the Performance Assessments and Composite Analyses for the Area 3 and Area 5 Radioactive Waste Management Sites at the Nevada National Security Site (Rev.3)

U.S. Department of Energy (DOE) Order 435.1, Radioactive Waste Management, requires that performance assessments (PAs) and composite analyses (CAs) for low-level radioactive waste (LLW) disposal facilities be maintained by the responsible field office. This plan describes the activities performed to maintain the PA and the CA for the Area 3 and Area 5 Radioactive Waste Management Sites (RWMSs) at the Nevada National Security Site (NNSS). The plan is based on DOE Order 435.1 Radioactive Waste Management (DOE 2007), DOE Manual 435.1-1, Radioactive Waste Management Manual (DOE 2011), and DOE Standard DOE-STD-5002-2017, Disposal Authorization Statement and Tank Closure Documentation (DOE 2017). The facility’s Disposal Authorization Statement (DAS) specifies conditions for the continuing operation of a LLW facility. The DAS is issued based on a review of the facility's PA, CA, the maintenance plan, preliminary closure plan, and preliminary monitoring plan. The DAS specifies the limits and conditions on construction, design, operations, and closure of the low-level waste facility based on these reviews. The Maintenance Plan uses an Unreviewed Disposal Question (UDQ)/Unreviewed Composite Analysis Question (UCAQ) change control process to identify, evaluate, and control planned or discovered changes affecting the PA, CA, DAS, or other documents composing the Radioactive Waste Management Basis (RWMB). The UDQ/UCAQ process uses the PA and CA GoldSim models to calculate updated results, assess the significance of changes, and to assess the need to revise the PA, CA, or DAS. In addition to the change control process, the Maintenance Plan requires an annual review of all changes and an annual assessment of the need to revise RWMB documents, plans, and programs. The cumulative effect of all changes is assessed annually by preparing a revised PA and CA baseline model that is used to update PA and CA results. The updated results are used to assess compliance with the PA performance objectives and the CA dose constraint, and to assess the need to revise the PAs, CAs, and other documents, plans, and programs supporting the RWMB. An Annual Summary Report documenting the results and conclusions of the annual review is prepared and submitted to DOE.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1984

NASA guidelines for assuring the adequacy and appropriateness of security safeguards in sensitive applications

The Office of Management and Budget (OMB) Circular A-71, transmittal Memorandum No. 1, requires that each agency establish a management control process to assure that appropriate administrative, physical and technical safeguards are incorporated into all new computer applications. In addition to security specifications, the management control process should assure that the safeguards are adequate for the application. The security activities that should be integral to the system development process are examined. The software quality assurance process to assure that adequate and appropriate controls are incorporated into sensitive applications is also examined. Security for software packages is also discussed.

Tompkins, F. G.↗
NASA NTRS1988

Testing and checkout experiences in the National Transonic Facility since becoming operational

The U.S. National Transonic Facility, constructed by NASA to meet the national needs for High Reynolds Number Testing, has been operational in a checkout and test mode since the operational readiness review (ORR) in late 1984. During this time, there have been problems centered around the effect of large temperature excursions on the mechanical movement of large components, the reliable performance of instrumentation systems, and an unexpected moisture problem with dry insulation. The more significant efforts since the ORR are reviewed and NTF status concerning hardware, instrumentation and process controls systems, operating constraints imposed by the cryogenic environment, and data quality and process controls is summarized.

Bruce, W. E., Jr.↗
NASA NTRS1966

Product traceability for NASA space systems

Identification as a specific point in a quality publication revealed in the year 1962, that it was a somewhat controversial subject with something lacking in groundrule definitions. The basic key to 'traceability' is establishment of proper identification numbers. These are: (1) serial numbers for control of individual articles, assemblies or equipment; (2) lot numbers for control of materials, articles and/or assemblies produced in homogeneous groups or through a controlled process; (3) date codes on articles or materials made by a continuous or controlled process and on such items subject to variations or degradation with age; or (4) combinations of the above.

Dyer, Morris K.↗
DOE OSTI2016

Processing temperature control of a diketopyrrolopyrrole- alt -thieno[2,3- b ]thiophene polymer for high-mobility thin-film transistors and polymer solar cells with high open-circuit voltages

Here, we synthesized a planar pDPPTTi-OD polymer based on diketopyrrolopyrrole (DPP) and thieno [2,3- b ] thiophene (TTi) and investigated the electrical properties of the pDPPTTi-OD polymer. pDPPTTi-OD films displayed a low optical bandgap of 1.57 eV, and HOMO and LUMO levels of –5.40 and –3.74 eV, respectively. The 150°C-annealed pDPPTTi-OD films showed a high hole mobility of 0.16 cm 2 V –1 s –1 in organic thin-film transistor (OTFT) devices. The photovoltaic properties of polymer solar cells (PSCs) incorporating the pDPPTTi-OD were also measured. A pDPPTTi-OD:PC 71 BM blend film was spin-coated at 25, 70 and 90 °C. High-temperature processing significantly improved the power conversion efficiency of PSCs by effectively reducing the PC 71 BM domain sizes, which improved the miscibility between pDPPTTi-OD and PC 71 BM. Furthermore, this work demonstrated that the TTi moiety is a useful donor building block for high-performance D–A type polymers in OTFTs and PSCs, and that processing temperatures should be controlled to fully realize the materials' beneficial intrinsic properties.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Testing of the Defense Waste Processing Facility Cold Chemical Dissolution Method in Sludge Batch 9 Qualification

For each sludge batch that is processed in the Defense Waste Processing Facility (DWPF), the Savannah River National Laboratory (SRNL) tests the applicability of the digestion methods used by the DWPF Laboratory for elemental analysis of Sludge Receipt and Adjustment Tank (SRAT) Receipt samples and SRAT Product process control samples. DWPF SRAT samples are typically dissolved using a method referred to as the DWPF Cold Chemical or Cold Chem Method (CC), (see DWPF Procedure SW4- 15.201). Testing indicates that the CC method produced mixed results. The CC method did not result in complete dissolution of either the SRAT Receipt or SRAT Product with some fine, dark solids remaining. However, elemental analyses did not reveal extreme biases for the major elements in the sludge when compared with analyses obtained following dissolution by hot aqua regia (AR) or sodium peroxide fusion (PF) methods. The CC elemental analyses agreed with the AR and PF methods well enough that it should be adequate for routine process control analyses in the DWPF after much more extensive side-by-side tests of the CC method and the PF method are performed on the first 10 SRAT cycles of the Sludge Batch 9 (SB9) campaign. The DWPF Laboratory should continue with their plans for further tests of the CC method during these 10 SRAT cycles.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

Towards in-situ certification of additively manufactured parts: the vital roles of physics-based and data-driven models

Certifying additively manufactured (AM) parts in-situ at the completion of a build is an enticing prospect, as it can help reduce the high costs associated with post-build testing and evaluation. However, achieving this goal presents significant challenges that may keep it aspirational for the foreseeable future. Nonetheless, incremental progress can pave the way forward. A critical aspect of in-situ certification involves continuous quality checking due to the random nature of the AM process and the difficulties in detecting defects or anomalies once layers are built over. While real-time in-situ monitoring strategies assisted by machine learning (ML) play a pivotal role in auditing part quality, they must ideally be supported by real-time (or near real-time) adaptive process control enabled by ML-assisted decision-making. By analyzing in-situ monitoring data in real-time (or near real- time) to dynamically adjust manufacturing parameters, such intervention can ensure AM parts are built to meet stringent certification standards. This can be achieved virtually by using high-fidelity performance models for the physical testing and evaluation tasks. In this short editorial, we discuss the key contributions made by data-driven and physics-based models in providing intelligence to the monitoring and process control tasks underpinning in-situ certification and in the simulation of the build’s performance under test and service conditions. While our focus lies in metal AM, the concepts discussed here are also relevant to other AM processes.

: In-situ monitoring↗
DOE OSTI2016

SU-G-TeP4-07: Automatic EPID-Based 2D Measurement of MLC Leaf Offset as a Quality Control Tool

Purpose: The MLC dosimetric leaf gap (DLG) and transmission are measured parameters which impact the dosimetric accuracy of IMRT and VMAT plans. This investigation aims to develop an efficient and accurate routine constancy check of the physical DLG in two dimensions. Methods: The manufacturer’s recommended DLG measurement method was modified by using 5 fields instead of 11 and by utilizing the Electronic Portal Imaging Device (EPID). Validations were accomplished using an ion chamber (IC) in solid water and a 2D IC array. EPID data was collected for 6 months on multiple TrueBeam linacs using both Millennium and HD MLCs at 5 different clinics in an international consortium. Matlab code was written to automatically analyze the images and calculate the 2D results. Sensitivity was investigated by introducing deliberate leaf position errors. MLC calibration and initialization history was recorded to allow quantification of their impact. Results were analyzed using statistical process control (SPC). Results: The EPID method took approximately 5 minutes. Due to detector response, the EPID measured DLG and transmission differed from the IC values but were reproducible and consistent with changes measured using the ICs. For the Millennium MLC, the EPID measured DLG and transmission were both consistently lower than IC results. The EPID method was implemented as leaf offset and transmission constancy tests (LOC and TC). Based on 6 months of measurements, the initial leaf-specific action thresholds for changes from baseline were set to 0.1 mm. Upper and lower control limits for variation were developed for each machine. Conclusion: Leaf offset and transmission constancy tests were implemented on Varian HD and Millennium MLCs using an EPID and found to be efficient and accurate. The test is effective for monitoring MLC performance using dynamic delivery and performing process control on the DLG in 2D, thus enhancing dosimetric accuracy. This work was supported by a grant from Varian Medical Systems.

61 RADIATION PROTECTION AND DOSIMETRY↗
NASA NTRS1990

Tolerating failures of continuous-valued sensors

One aspect of fault tolerance in process control programs is the ability to tolerate sensor failure. A methodology for transforming a process control program that cannot tolerate sensor failures onto one that can is presented. Issues addressed include modifying specifications in order to accommodate uncertainty in sensor values and averaging sensor values in a fault tolerant manner. In addition, a hierarchy of sensor failure models is identified, and both the attainable accuracy and the run-time complexity of sensor averaging with respect to this hierarchy is discussed.

Marzullo, Keith↗