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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 1,135 records · Page 63
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Technical Oversight of the Nancy Grace Roman Space Telescope Optical Telescope Assembly (OTA) Element Procurement: Opportunities, Challenges, & Lessons Learned (2024 Update)

Nancy Grace Roman Space Telescope Optical Telescope Assembly (OTA) is an out-of-house procurement from L3Harris currently being integrated and tested in Rochester, NY. Building upon L3Harris’s decades of success producing world-class optical systems for government and commercial customers offers NASA a proven partner and a tremendous opportunity for high performance and value. Inheriting significant portions of the telescope (including the primary and secondary mirror, composite metering structures and alignment drives) from a previous program presents the opportunity to save cost and schedule but constrains the design space for the unique challenges of the Roman mission. This seminar will cover a brief description of the OTA and its history, some of the challenges posed by incorporating an established product line and inherited hardware into a Class A mission, and some approaches and lessons learned that may be helpful for those structuring new missions or providing technical oversight of out-of-house procurements.

Joshua Abel↗
NASA NTRSDate not supplied

Challenges in Remote-Sensing of Hail: Examining the Performance and Biases of Satellite Hail Retrievals Using Aqua MODIS Visible/IR and AMSR-E Passive-Microwave Observations

Hail poses threats to myriad aspects of human life and society, infrastructure, and agriculture. Scientifically, hail can often cause large errors in precipitation retrieval and estimation, posing challenges to establishing the current climatology of severe storms and their future trend in a changing Earth system. Fortunately, hailstorms exhibit distinct signatures in spaceborne remote-sensing datasets (e.g. overshooting cloud tops in visible/IR, or brightness temperature depressions in passive-microwave imagery). Approaches that leverage these signatures, however, are not without their pitfalls,: passive-microwave channels have large footprints and exhibit non-uniform beam filling. Visible/IR instruments have fine horizontal resolution but are limited by their insensitivity to processes occurring below cloud top. Large horizontal areas of smaller scatterers may also meaningfully lower the brightness temperatures, especially if they are able to occupy large portions of the footprint. Radiative transfer simulations show that low frequencies such as 19- and 37-GHz can be scattered to extremely low brightness temperatures by high concentrations of smaller (graupel-sized) ice scatterers, especially in larger features that are more likely to occupy the footprint, which may cause climatologies to overestimate the frequency severe hail. To address this, we investigate the nearly simultaneous and colocated MODIS (visible/IR) and AMSR-E (passive-microwave) onboard the Aqua satellite to leverage both datasets together, pairing AMSR-E and MODIS signatures of severe convection with ground-based weather radar, severe weather reports, and environmental parameters defined by the MERRA-2 reanalysis over CONUS, and then explore the performance and challenges of the algorithm when we expand outside the United States into six different geographical regimes throughout the Aqua domain.

Sarah D Bang↗
NASA NTRSDate not supplied

SR-1 Freedom Thermal Architecture Challenges

The SR-1 Freedom mission aims to demonstrate nuclear electric propulsion (NEP) and deliver the Skyfall helicopter payload to Mars. Repurposing the existing Gateway Power and Propulsion Element (PPE) spacecraft and combining it with a 20 kWe-class nuclear power module (NPM) presents a variety of thermal architecture challenges. These include unprecedented waste heat rejection requirements, integration with a spacecraft bus originally designed for a different mission profile, and novel packaging constraints. This presentation will describe the simplified concept of operations as it relates to on-orbit thermal environments, early-phase architecture trades and supporting analyses, and planned forward work. We will also discuss our strategy for integrated thermal modeling of the complete spacecraft and examples of interface challenges necessitated by this ambitious effort.

Thermal↗
DOE OSTI2014

Physics challenges for advanced fuel cycle assessment

Advanced fuel cycles and associated optimized reactor designs will require substantial improvements in key research area to meet new and more challenging requirements. The present paper reviews challenges and issues in the field of reactor and fuel cycle physics. Typical examples are discussed with, in some cases, original results.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2015

MaRIE 1.0: The Matter-Radiation Interactions in Extremes Project, and the Challenge of Dynamic Mesoscale Imaging

The Matter-Radiation Interactions in Extremes project will build the experimental facility for the time-dependent control of dynamic material performance. An x-ray free electron laser at up to 42-keV fundamental energy and with photon pulses down to sub-nanosecond spacing, MaRIE 1.0 is designed to meet the challenges of time-dependent mesoscale materials science. Those challenges will be outlined, the techniques of coherent diffractive imaging and dynamic polycrystalline diffraction described, and the resulting requirements defined for a coherent x-ray source. The talk concludes with the role of the MaRIE project and science in the future.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Quantifying Scheduling Challenges for Exascale System Software

The move towards high-performance computing (HPC) ap- plications comprised of coupled codes and the need to dra- matically reduce data movement is leading to a reexami- nation of time-sharing vs. space-sharing in HPC systems. In this paper, we discuss and begin to quantify the perfor- mance impact of a move away from strict space-sharing of nodes for HPC applications. Specifically, we examine the po- tential performance cost of time-sharing nodes between ap- plication components, we determine whether a simple coor- dinated scheduling mechanism can address these problems, and we research how suitable simple constraint-based opti- mization techniques are for solving scheduling challenges in this regime. Our results demonstrate that current general- purpose HPC system software scheduling and resource al- location systems are subject to significant performance de- ciencies which we quantify for six representative applica- tions. Based on these results, we discuss areas in which ad- ditional research is needed to meet the scheduling challenges of next-generation HPC systems.

C.1.2 [Multiprocessors]: Parallel Processors↗
DOE OSTI2016

Rating Correlations Between Customs Codes and Export Control Lists: Assessing the Needs and Challenges

Correlation tables are the linchpins between the customs codes used to classify commodities in international trade and the control lists used for strategic trade control (STC) purposes. While understanding the customs classification system can help the STC community better understand strategic trade flows, better identify which trade operations require permits, and more effectively detect illegal exports, the two systems are different in scope, philosophy, content, and objectives. Many indications point to the limitations of these correlation tables, and it is important to understand the nature of the limitations and the complex underlying reasons to conceive possible improvements. As part of its Strategic Trade and Supply Chain Analytics Initiative, Argonne National Laboratory supported a study of a subset of the European Union’s TARIC correlation table. The study included development of a methodology and an approach to rating the quality and relevance of individual correlations. The study was intended as a first step to engage the STC community in deflections and initiatives to improve the conception and use of correlations, and its conclusions illustrate the scope and complex nature of the challenges to overcome. This paper presents the two classification systems, analyzes the needs for correlation tables and the complex challenges associated with them, summarizes key findings, and proposes possible ways forward.

commodity classification↗
DOE OSTI2015

Challenge Online Time Series Clustering For Demand Response A Theory to Break the ‘Curse of Dimensionality'

The advent of smart meters and advanced communication infrastructures catalyzes numerous smart grid applications such as dynamic demand response, and paves the way to solve challenging research problems in sustainable energy consumption. The space of solution possibilities are restricted primarily by the huge amount of generated data requiring considerable computational resources and efficient algorithms. To overcome this Big Data challenge, data clustering techniques have been proposed. Current approaches however do not scale in the face of the “increasing dimensionality” problem where a cluster point is represented by the entire customer consumption time series. To overcome this aspect we first rethink the way cluster points are created and designed, and then design an efficient online clustering technique for demand response (DR) in order to analyze high volume, high dimensional energy consumption time series data at scale, and on the fly. Our online algorithm is randomized in nature, and provides optimal performance guarantees in a computationally efficient manner. Unlike prior work we (i) study the consumption properties of the whole population simultaneously rather than developing individual models for each customer separately, claiming it to be a ‘killer’ approach that breaks the “curse of dimensionality” in online time series clustering, and (ii) provide tight performance guarantees in theory to validate our approach. Our insights are driven by the field of sociology, where collective behavior often emerges as the result of individual patterns and lifestyles.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2017

Challenges and Opportunities of Gas Engine Driven Heat Pumps: Two Case Studies

Gas engine driven heat pumps (GHP) currently hold a small market share. This share is considerably smaller than what the full potential of GHP technology can realize. Of the main benefits of the GHP technology is their better primary energy utilization mainly due to the ability to recover the engine heat. However, development and market penetration of GHP technology have been challenged by various market and technical barriers. The main barriers are the high initial cost, low awareness of the technology, and poor perception. On the other hand, several opportunities arise that the GHP technology can take advantage of to increase its market share. The most direct opportunity is the abundance of cheap natural gas. This translates directly into monetary savings and higher ROI. GHPs offer the advantage of reducing the peak demand by 80% compared to electric counterpart. From the point of view of utilities, this eliminates the need for lower-efficiency peaking power plants and over-expansion only to cover maximum peak times. From the point of view of renewable customers, GHPs eliminate the need to buy power from the grid at a high price. This is especially important in hot climates with high cooling loads. When built and operated as distributed generation, GHPs can improve the reliability of power delivery to consumers. The paper discusses the challenges and opportunities as seen during the development and commercialization of two different GHP products; a 10-ton packaged unit and 5-ton split unit.

Abu-Heiba, Ahmad↗
DOE OSTI2016

hapter 10 - Challenges and Opportunities for the Mobilisation of Forest Bioenergy in the Boreal and Temperate Biomes. In the book Mobilisation of Forest Bioenergy in the Boreal and Temperate Biomes.

This book identifies opportunities and challenges for the mobilisation of sustainable forest biomass from supply chains operating in the boreal and temperate biomes. The respective feedstock plays a critical role in meeting global deployment levels for bioenergy, which in turn are necessary to stabilize global greenhouse gas emissions and atmospheric carbon levels. Many aspects of bioenergy supply chains (e.g., logistics and trade, supply chain variability, technology learning and transfer, governance, organizational structures) present both challenges and opportunities, and relate to all three dimensions of sustainability. Energy and forest systems can be integrated across landscapes and organizations to establish attractive solutions guided by good governance of forest management and biomass use (e.g., policies, regulations, standards and certification systems). Nevertheless, substantial gains in forest bioenergy mobilisation can only be achieved with an important increase in forest management intensity causing a larger appropriation of forest net primary production (NPP). Such an intensification would likely require fundamental shifts in the forest systems and considerable societal change in some countries. A multifaceted policy effort to support a broad array of technological, structural, and behavioral changes is needed to enable energy and industrial transitions and the development of supply chains that deliver feedstock to a range of conversion and utilization routes.

09 BIOMASS FUELS↗
DOE OSTI2018

Market Opportunities and Challenges for Pumped Hydro in an Evolving Power Grid: Preprint

The paper explores several market opportunities and challenges for pumped storage hydropower (PSH) related to ongoing changes in the electric power grid. Two PSH technologies are investigated - single-speed pump/turbine and variable-speed pump/turbine units - under three variable generation penetration scenarios. The results provide a way to do relative comparisons of the opportunities and challenges that pumped storage hydro faces as the variable generation in a system increases.

13 HYDRO ENERGY↗
DOE OSTI2016

Safety Analysis Challenges With Restart of the Idaho National Laboratory (INL) Transient Reactor Test (TREAT) Facility

Safety Analysis Challenges With Restart of the Idaho National Laboratory Transient Reactor Test (TREAT) Facility Dr. James Parry David Broussard Anthony LaPorta Douglas Gerstner Battelle Energy Alliance Idaho National Laboratory P.O. Box 1625/MS6194 Idaho Falls, ID 83415 The Transient Reactor Test Facility, commonly referred to as TREAT, is an air-cooled, thermal spectrum test reactor facility designed to: • Induce intense fission heating in the nuclear fuel being tested. • Test nuclear reactor fuels under severe reactor-accident conditions. • Study fuel meltdowns, metal-water reactions, interactions between overheated fuel and coolant, and the transient behavior of fuels for high-temperature systems. • Provide nondestructive test data through neutron radiography of fuel samples. • Allow for the detailed monitoring of the experiments during the test. TREAT was specifically designed to test prototypic-sized reactor fuel pins and bundles under transient power conditions. During its 35 year operating history, it conducted thousands of transient experiments. Today, these capabilities are required for predicting safety margins for next generation fuels and advanced reactor design safety. Even though TREAT has not operated since 1994, return to operable conditions and resumption of testing will occur in FY 2018. This paper discusses the unique challenges with performing and documenting the safety analyses that demonstrate that the TREAT restart may be performed safely. This includes a discussion of 1) the TREAT capability, design, and operations, 2) identification of the format and content of the required safety basis document changes, and 3) demonstration that the consequences of potential accidents during TREAT operations meet the consequence guidelines.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2019

Evaluation and Validation Approaches for Simulation of Social Behavior: Challenges and Opportunities

While models of social systems have grown in scope to represent increasingly complex phenomena, efforts to validate these models against observations suffer from a number of challenges that include the lack of shared approaches, the use of single-dimensional evaluation criteria, and the difficulty in evaluating causal mechanisms. Moreover, current evaluation approaches suffer from sensitivity of the existing measurements to initial conditions and model assumptions, and failure to account for uncertainty. These effects lead to the lack of generalizability to new contexts, inability to replicate the validation approach for new models, and difficulties in interpretation of validation results. These challenges can be addressed by building a set of diverse and robust evaluation metrics and by developing best practices for comparative, reproducible validation of varied social simulation approaches against real-world data. Herein, we outline several best practices for data-drive model validation, such as defining evaluation strategies consistent with the intended use case and defining broad comparison criteria to highlight both model strengths and weaknesses. Leveraging common validation practices will enable robust analysis of simulation performance across diverse social scenarios and modeling approaches.

Saldanha, Emily G.↗
DOE OSTI2019

Getting Data Out of the Ground: Modern Data Challenges Facing EGS Collab, the DOE Geothermal Data Repository, and the Geothermal Industry

The amount of data being generated by the geothermal industry is increasing exponentially. Advanced tools, higher resolution sensors, and digitally integrated equipment are providing valuable insight into geothermal exploration and operational efficiencies, but the volumes of data they generate and the unique properties of Enhanced Geothermal System (EGS) projects are creating challenges of their own. This paper explores those challenges and the steps the U.S. Department of Energy (DOE) is taking to address them through comprehensive data management strategies, improvements to DOE's Geothermal Data Repository (GDR), and the development of a secure data collaboration tool for DOE's Frontier Observatory for Research in Geothermal Energy (FORGE) and EGS Collab projects.

15 GEOTHERMAL ENERGY↗
DOE OSTI2019

Data Management Challenges of Exascale Scientific Simulations: A Case Study with the Gyrokinetic Toroidal Code and ADIOS

The push towards exascale computing and the recent introduction of multi-petascale supercomputers have enabled science applications to run complex simulations. However, the gap between compute and I/O has grown wider, even as applications seek to generate and persist increasing amounts of data. Optimizing I/O is challenging and remains a bottleneck at scale. In this paper, we present initial I/O performance results of running Gyrokinetic Toroidal Code (GTC) on Summit, a 200 Petaflop system at Oak Ridge National Laboratory. To manage the complex data in GTC, we use ADIOS, an I/O and data management middleware that provides a rich set of APIs to manage and interact with scientific data. We discuss optimizations performed to obtain improvements in I/O performance and identify a set of challenges that will drive the design and development of next generation data management libraries.

Wan, Lipeng↗
DOE OSTI2019

An Overview of the United States Department of Energy's Nuclear Criticality Safety Program and Future Challenges

The United States (US) Department of Energy (DOE)/National Nuclear Security Administration (NNSA) Nuclear Criticality Safety Program (NCSP) was formally established in January 1998 as part of the Defense Nuclear Facility Safety Board (DNFSB) Recommendation 97-2 implementation plan. The NCSP was initially focused on seven NCSP tasks: Critical Experiments, Benchmarking, Analytical Methods, Nuclear Data, Training and Qualification, Information Preservation and Dissemination, and Applicable Ranges of Bounding Curves and Data. The first NCSP 5-year plan was published in August 1999. Now, more than 20 years later, NCSP continues to serve the United States and the nuclear criticality safety (NCS) community around five technical program elements (TPEs): Analytical Methods, Information Preservation and Dissemination, Integral Experiments, Nuclear Data, and Training and Education. NCSP has three chartered support groups, the Criticality Safety Support Group, the Nuclear Data Advisory Group, and the DOE Criticality Safety Coordinating Team, all of which provide technical advisement to the NCS community, to DOE, and to the NCSP manager. NCSP has a comprehensive mission and vision document that provides technical and budget priorities for TPE attributes and goals to ensure that the needs of the NCS community and DOE NCS are prioritized appropriately to meet the goals defined by the 1998 DNFSB recommendation. Like any DOE/NNSA program, NCSP faces significant challenges in the future that involves program funding, rising nuclear facility costs, aging critical assembly infrastructure, knowledge retention, and other issues. This paper discusses NCSP and provides some insights into these and other challenges moving into the future.

Bowen, Douglas G.↗
DOE OSTI2019

Practical Challenges and Failure Modes During Fabrication of Haynes 230 Micro-Pin Solar Receivers for High Temperature Supercritical Carbon Dioxide Operation

Printed circuit heat exchangers (PCHX) fabricated from high nickel alloys have shown promise as primary heat exchangers, recuperators, and solar receivers for high temperature and pressure supercritical carbon dioxide power cycles. There are numerous challenges in fabricating these devices including forming channel features, joining via diffusion or transient liquid phase bonding, and brazing/welding of headers. Commercial entities are understandably hesitant to share propriety best practices, and both commercial and non-commercial entities working on these components tend not to publically share failures and mistakes. However, sharing of this information could prevent similar costly errors and further the understanding of the coupled manufacturing, materials and mechanics issues in creating these components. Thus, in this paper, we document the challenges, failures, and mitigation methods uncovered in fabrication of prototype micro-pin based solar thermal receivers constructed of Haynes 230 and fabricated through a combination of photochemical machining (PCM), wire electrical discharge machining (EDM), transient liquid phase (TLP) bonding, vacuum brazing, and gas tungsten arc welding (GTAW). The receiver is designed to absorb concentrated solar fluxes greater than 140 W cm-2, while heating supercritical carbon dioxide from 550 °C to 720 °C at a pressure of 20 MPa to 25 MPa. The prototype receiver consists of a thin (~ 450 µm), Haynes 230 coversheet bonded to a 15 cm × 15 cm Haynes 230 micro-pin plate. The pieces are joined using a TLP bonding process with a nickel-phosphorus interlayer. Prior to bonding, micro-pins with height ~150 µm and diameter 300 µm are fabricated using PCM in the plate, and through slot features are made using wire EDM. Finally, flow headers are joined to the microchannel plate through a combination of vacuum brazing and GTAW. During hydrostatic proof testing, the prototype device failed when the coversheet delaminated from the pin array at a pressure of 290 bar. A failure analysis including scanning electron microscopy (SEM) to view failure sites and energy-dispersive X-ray spectroscopy (EDS) to evaluate elemental analysis of the failed areas was conducted. The failure modes can be broadly categorized as (1) failures potentially relating to reliquification of the transient liquid phase bonds between the micro-pins plate and coversheet during post-processing, (2) failures related to manufacturing defects, and (3) failures attributed to design.

14 SOLAR ENERGY↗