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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 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
DOE OSTI2010

Computing contingency statistics in parallel : design trade-offs and limiting cases.

Statistical analysis is typically used to reduce the dimensionality of and infer meaning from data. A key challenge of any statistical analysis package aimed at large-scale, distributed data is to address the orthogonal issues of parallel scalability and numerical stability. Many statistical techniques, e.g., descriptive statistics or principal component analysis, are based on moments and co-moments and, using robust online update formulas, can be computed in an embarrassingly parallel manner, amenable to a map-reduce style implementation. In this paper we focus on contingency tables, through which numerous derived statistics such as joint and marginal probability, point-wise mutual information, information entropy, and {chi}{sup 2} independence statistics can be directly obtained. However, contingency tables can become large as data size increases, requiring a correspondingly large amount of communication between processors. This potential increase in communication prevents optimal parallel speedup and is the main difference with moment-based statistics (which we discussed in [1]) where the amount of inter-processor communication is independent of data size. Here we present the design trade-offs which we made to implement the computation of contingency tables in parallel. We also study the parallel speedup and scalability properties of our open source implementation. In particular, we observe optimal speed-up and scalability when the contingency statistics are used in their appropriate context, namely, when the data input is not quasi-diffuse.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2013

An Analysis Framework for Investigating the Trade-offs Between System Performance and Energy Consumption in a Heterogeneous Computing Environment

Rising costs of energy consumption and an ongoing effort for increases in computing performance are leading to a significant need for energy-efficient computing. Before systems such as supercomputers, servers, and datacenters can begin operating in an energy-efficient manner, the energy consumption and performance characteristics of the system must be analyzed. In this paper, we provide an analysis framework that will allow a system administrator to investigate the tradeoffs between system energy consumption and utility earned by a system (as a measure of system performance). We model these trade-offs as a bi-objective resource allocation problem. We use a popular multi-objective genetic algorithm to construct Pareto fronts to illustrate how different resource allocations can cause a system to consume significantly different amounts of energy and earn different amounts of utility. We demonstrate our analysis framework using real data collected from online benchmarks, and further provide a method to create larger data sets that exhibit similar heterogeneity characteristics to real data sets. This analysis framework can provide system administrators with insight to make intelligent scheduling decisions based on the energy and utility needs of their systems.

Friese, Ryan↗
DOE OSTI2016

Local, Regional, and Global Trade-Offs of Hydropower Relicensing Decisions An Analysis of Electric Generation, Revenue, Electricity Market, Greenhouse Gas Emissions, and Local Environmental Impacts

Large hydropower systems incur various impacts on society and the environment, but the manner in which these systems are operated can determine the severity of these impacts. The federal hydropower relicensing process – which occurs only once every 30-50 years – examines a number of potential impacts, but disregards others. This paper identifies some of the local, regional, and global trade-offs that should be examined more explicitly in relicensing proceedings. These include higher-resolution analyses of impacts on generation and revenue (including ancillary services) and the potential greenhouse gas impacts of different hydropower operating regimes. Any reduction of low-carbon generation may result in global environmental and social harms if it is replaced by fossil fuel generation. Although rarely quantified in the hydropower relicensing process, this is an important value in understanding the range of costs and benefits of different operating proposals. Using a case study of the Yuba River Development Project, this study finds that an environmentally protective operating regime reduces electric generation by 6.1% but increases ancillary services provision by 1.9% on average. The reduced hydropower generation is replaced by natural gas generation, resulting in an increase in CO2 emissions with a global social cost of about $1 million annually.

13 HYDRO ENERGY↗
DOE OSTI2021

DOME Trade Study Package

Package summarizes all trade studies done up to conceptual design. Intended audience is DOE.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2018

Retooling a Trade Association in a Challenged Industry: The Nuclear Energy Institute Story - 18503

The U.S. Nuclear industry is facing significant challenges to maintain economic competitiveness in an electricity supply sector where advances in natural gas, wind, and solar technologies are reshaping the marketplace. As clean and reliable baseload generation, nuclear still has a valuable role to play. But in order for the power of the atom to remain available for meeting the nation's energy, environmental, and national security needs, it will be imperative that industry leadership innovate and become more efficient at a pace that matches the competition. Industry leaders rely, to a large extent, on their trade association - the Nuclear Energy Institute (NEI) - to be the prime mover in championing initiatives that will enable a successful future. NEI realized that, in the face of an increasingly difficult economic situation, it must become both leaner and more forward looking - it would have to extend its reach and influence while at the same time reigning in costs to its membership. Therefore, on January 17, 2017 NEI completed a restructuring to improve member value and organizational effectiveness. This restructuring was designed in recognition that the nuclear industry is at a pivotal time, and NEI had a unique opportunity to change its trajectory and underline the importance of nuclear energy's role in the nation's critical infrastructure. NEI is now better positioned to support the existing reactor fleet, promote commercialization of advanced reactors, and drive American leadership in commercial nuclear exports and technology around the world. NEI began this restructuring in the fall of 2016 when it consolidated Government Affairs, Communications, Policy and Public Affairs under a new External Affairs function. The January 2017 action extended that effort across the remainder of the organization, ensuring that the organization is highly aligned, member-focused and results driven. The new NEI takes pride in the fact that it is comprised of talented employees who are passionate about nuclear energy and can make a difference for our membership. With this team in place, NEI looks forward to advancing the interests of the nuclear industry while contributing to a safer, cleaner and more productive world. This paper will examine the details of how this new organization was constructed, provide an overview of the National Nuclear Energy Strategy it developed to guide its efforts, examine the trials and tribulations that come along with disruptive change, and reflect on what has been accomplished in the retooled organizations first year. (authors)

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2025

Key Design Trades for a Near-term Lunar Fission Surface Power System

NASA and DOE have been developing concepts for lunar and Mars Fission Surface Power (FSP) systems for decades and have considered many different technologies and system variations. In 2023, three contractor teams completed Phase 1 conceptual design studies on a 40 kWe lunar FSP system in response to a modest set of NASA requirements and goals. A government team consisting of NASA Glenn Research Center (GRC), Los Alamos National Laboratory (LANL), and Idaho National Laboratory (INL) was formed to develop an independent design approach that adhered to the same requirements and goals posed to the contractor teams. GRC provided expertise, analysis, and design decisions for the power conversion, heat rejection, power management & distribution (PMAD), and mission integration. LANL and INL provided expertise, analysis, and design decisions for the reactor and shielding. The goal of the government study was to develop representative concepts that could be used in NASA architecture studies, guide government technology investments, and inform Phase 2 requirements definition. This paper provides a summary of the key technology options, system-level trades, and mission-level concept-of-operations.

99 - GENERAL AND MISCELLANEOUS↗
DOE OSTI2023

Python codes for the paper - "Trade-offs in the latent representation of microstructure evolution"

SAND2024-00946O Python codes used in "Trade-offs in the latent representation of microstructure evolution," a manuscript accepted for publication in Acta Materialia, are part of a repository. The code was developed to perform analysis of microstructure evolution. The repository consists of two main directories: models, which train and test models such as autoencoders and diffusion maps, and analysis, which analyzes microstructures. Source code is used to perform dimensionality reduction of microstructure data for analysis of its evolution in time. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

Dingreville, Remi↗
DOE OSTI2023

Hybrid Monomer Design Synergizing Property Trade‐offs in Developing Polymers for Circularity and Performance

Abstract Current search for more sustainable plastics seeks to redesign polymers possessing both chemical recyclability to monomer for a circular plastics economy and desirable performance that can rival or even exceed today's non‐recyclable or hard‐to‐recycle petroleum‐based incumbents. However, within a traditional monomer framework it is challenging to optimize, concurrently , contrasting polymerizability/depolymerizability and recyclability/performance properties. Here, we highlight the emerging hybrid monomer design strategy to develop intrinsically circular polymers with tunable performance properties, aiming to unify desired, but otherwise conflicting, properties in a single monomer. Conceptually, this design hybridizes parent monomer pairs of contrasting, mismatching, or matching properties into offspring monomers that not only unify the above‐described conflicting properties but also radically alter the resultant polymer properties far beyond the limits of what either parent homopolymers or their copolymers can achieve.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Trade can buffer climate-induced risks and volatilities in crop supply

Climate change is intensifying the frequency and severity of extreme events, posing challenges to food security. Corn, a staple crop for billions, is particularly vulnerable to heat stress, a primary driver of yield variability. While many studies have examined climate impact on average corn yields, little attention has been given to the climate impact on production volatility. This study investigates the future volatility and risks associated with global corn supply under climate change, evaluating the potential benefits of two key adaptation strategies: irrigation and market integration. A statistical model is employed to estimate corn yield response to heat stress and utilize NEX-GDDP-CMIP6 climate data to project future production volatility and risks of substantial yield losses. Three metrics are introduced to quantify these risks: Sigma (σ), the standard deviation of year-on-year yield change, which reflects overall yield volatility; Rho (ρ), the risk of substantial loss, defined as the probability of yield falling below a critical threshold; and Beta (β), a relative risk coefficient that captures the volatility of a region's corn production compared to the globally integrated market. The analysis reveals a concerning trend of increasing year-on-year yield volatility (σ) across most regions and climate models. This volatility increase is significant for key corn-producing regions like Brazil and the United States. While irrigated corn production exhibits a smaller rise in volatility, suggesting irrigation as a potential buffer against climate change impacts, it is not a sustainable option as it can cause groundwater depletion. On the other hand, global market integration reduces overall volatility and market risks significantly with less sustainability concerns. Furthermore, these findings highlight the importance of a multidimensional approach to adaptation in the food sector. While irrigation can benefit individual farmers, promoting global market integration offers a broader solution for fostering resilience and sustainability across the entire food system.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2016

Solving the Optimal Trading Trajectory Problem Using a Quantum Annealer

We solve a multi-period portfolio optimization problem using D-Wave Systems' quantum annealer. We derive a formulation of the problem, discuss several possible integer encoding schemes, and present numerical examples that show high success rates. The formulation incorporates transaction costs (including permanent and temporary market impact), and, significantly, the solution does not require the inversion of a covariance matrix. The discrete multi-period portfolio optimization problem we solve is significantly harder than the continuous variable problem. We present insight into how results may be improved using suitable software enhancements and why current quantum annealing technology limits the size of problem that can be successfully solved today. Here, the formulation presented is specifically designed to be scalable, with the expectation that as quantum annealing technology improves, larger problems will be solvable using the same techniques.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2023

Assessing hybrid vigour using the thermal sensitivity of physiological trade-offs in tiger salamanders

Hybridization between species affects biodiversity and population sustainability in numerous ways, many of which depend on the fitness of the hybrid relative to the parental species. Hybrids can exhibit fitter phenotypes compared to the parental lineages, and this ‘hybrid vigour’ can then lead to the extinction of one or both parental lines. In this study, we analysed the relationship between water loss and gas exchange to compare physiological performance among three tiger salamander genotypes—the native California tiger salamander (CTS), the invasive barred tiger salamanders (BTS) and CTS × BTS hybrids across multiple temperatures (13.5°C, 20.5°C and 23.5°C). We developed a new index of performance, the water-gas exchange ratio (WGER), which we define as the ratio of gas exchange to evaporative water loss (μL V O 2 /μL H 2 O). The ratio describes the ability of an organism to support energetically costly activities with high levels of gas exchange while simultaneously limiting water loss to lower desiccation risk. We used flow through respirometry to measure the thermal sensitivity of metabolic rate and resistance to water loss of each salamander genotype to compare indices of physiological performance. We found that temperature had a significant effect on metabolic rate and resistance to water loss, with both traits increasing as temperatures warmed. Across genotypes, we found that hybrids have a higher WGER than the native CTS, owing to a higher metabolic rate despite having a lower resistance to water loss. These results provide a greater insight into the physiological mechanisms driving hybrid vigour and offer a potential explanation for the rapid spread of salamander hybrids. More broadly, our introduction of the WGER may allow for species- or lineage-wide comparisons of physiological performance across changing environmental conditions, highlighting the insight that can be gleaned from multitrait analysis of organism performance.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS2003

MSL project trades model

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trades modeling rapid system engineering↗