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All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

2024 Photovoltaic Inverter Reliability Workshop Summary Report & Proceedings

The National Renewable Energy Laboratory (NREL) organized the 2024 Photovoltaic Inverter Reliability Workshop on April 11-12, 2024, hosted at NREL's South Table Mountain campus in Golden, Colorado. The workshop was organized around seven key topics, including the present state of inverter reliability; solutions for reliability challenges; life cycle cost and ownership issues; testing, standards, performance, and reliability metrics; data reporting, analytics, and sharing; and the future of PV inverter reliability research. Participants included inverter manufacturers, national laboratory researchers, academics, independent testing laboratories, and more. Over the course of the two-day workshop, attendees arrived at several key priorities and conclusions. This report summarizes these conclusions and then collects presentations from the workshop into a record of the workshop's proceedings.

14 SOLAR ENERGY↗
DOE OSTI2022

Importance of Standardizing Analytical Characterization Methodology for Improved Reliability of the Nanomedicine Literature

Understanding the interaction between biological structures and nanoscale technologies, dubbed the nano-bio interface, is required for successful development of safe and efficient nanomedicine products. The lack of a universal reporting system and decentralized methodologies for nanomaterial characterization have resulted in a low degree of reliability and reproducibility in the nanomedicine literature. As such, there is a strong need to establish a characterization system to support the reproducibility of nanoscience data particularly for studies seeking clinical translation. Here, we discuss the existing key standards for addressing robust characterization of nanomaterials based on their intended use in medical devices or as pharmaceuticals. We also discuss the challenges surrounding implementation of such standard protocols and their implication for translation of nanotechnology into clinical practice. We, however, emphasize that practical implementation of standard protocols in experimental laboratories requires long-term planning through integration of stakeholders including institutions and funding agencies.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2025

Creating Accurate Methane Emission Inventories through Data-Driven Airborne Survey Strategies

Because natural gas emits less carbon than other fossil fuels, it holds promise as a green energy transition fuel. However, the overall carbon footprint of natural gas is significantly elevated by methane emissions that occur during its production and transmission (Cusworth et al. 2022). Methane “super-emitters,” while comprising only about 1% of sites, are responsible for the majority of oil- and gas-sourced methane emissions, making their detection and mitigation critical in reducing the climate impact of natural gas and in meeting national and global sustainability goals (Sherwin et al. 2024). Yet, despite advancements in detection, significant uncertainties remain regarding the size, frequency, and duration distributions of methane emissions (e.g., Frankenberg et al. 2016, Cusworth et al. 2022, Chen, Sherwin et al. 2022, Conrad et al. 2023, Johnson et al. 2023, Sherwin et al. 2024) underscoring the need for comprehensive emissions inventories segmented by basin across the US. Airborne surveys are well-suited for collecting data to build these comprehensive, basin-level inventories because they allow for extensive spatial coverage, and have the spatial resolution, and the sensitivity to pinpoint individual methane sources. As remote sensing technologies enable rapid basin-scale surveys, it is imperative to establish scientifically and statistically robust standards to generate reliable and actionable emissions inventories. Recent work has shown that differences in airborne sampling strategies, detection technologies, and analysis can lead to large differences between survey conclusions if not correctly accounted for (Chen et al. 2024). This elevates the importance of incorporating proper sampling and analysis techniques when designing a methane emissions monitoring campaign to produce accurate results and facilitate cross-study comparisons. In this paper, we describe a survey strategy designed using the latest conclusions from the literature to align results from different aerial surveys. We identify several sampling and analysis principles, including large sample sizes, balanced sampling across oil and gas production, careful survey area definition, and a unified protocol for analysis, to be vital to producing an unbiased estimate of basin-scale emissions. We present results from a Department of Energy-funded project that deployed this survey strategy in two understudied oil and gas- producing regions in the United States: the Haynesville Basin in Texas and Louisiana, and the Woodford Shale in the Anadarko Basin in Oklahoma.

03 NATURAL GAS↗
NASA NTRS2015

A Vision for Spaceflight Reliability: NASA's Objectives Based Strategy

In defining the direction for a new Reliability and Maintainability standard, OSMA has extracted the essential objectives that our programs need, to undertake a reliable mission. These objectives have been structured to lead mission planning through construction of an objective hierarchy, which defines the critical approaches for achieving high reliability and maintainability (R M). Creating a hierarchy, as a basis for assurance implementation, is a proven approach; yet, it holds the opportunity to enable new directions, as NASA moves forward in tackling the challenges of space exploration.

Strategy↗
NASA NTRS2015

Spaceflight Reliability: An Objectives-Based Strategy

In defining the direction for a new Reliability and Maintainability standard, OSMA has extracted the essential objectives that our programs need, to undertake a reliable mission. These objectives have been structured to lead mission planning through construction of an objective hierarchy, which defines the critical approaches for achieving high reliability and maintainability (R M). Creating a hierarchy, as a basis for assurance implementation, is a proven approach; yet, it holds the opportunity to enable new directions, as NASA moves forward in tackling the challenges of space exploration.

Reliability and Maintainability↗
DOE OSTI2017

PCOR Partnership Best Practices Manual for Subsurface Technical Risk Assessment of Geologic CO 2 Storage Projects

In 2003, the U.S. Department of Energy established the Regional Carbon Sequestration Partnerships (RCSP) Initiative to help develop technology, infrastructure, and regulations needed to facilitate large-scale carbon dioxide (CO 2 ) geologic storage (herein “storage”) and support deployment of commercial carbon capture and storage projects. The Plains CO 2 Reduction (PCOR) Partnership, led by the Energy & Environmental Research Center (EERC), is one of seven partnerships created by this program. The PCOR Partnership is publishing a series of best practices manuals for each of the four PCOR Partnership-defined primary technical elements of a storage site: site characterization; modeling and simulation; risk assessment; and monitoring, verification, and accounting. This document describes the risk assessment process for evaluating subsurface technical risks associated with a CO 2 storage project. This best practices manual identifies the key elements comprising a risk assessment for a CO 2 storage complex and defines important risk management terminology and technical factors that are unique to the geologic storage of CO 2 . It also provides best practices for implementing a risk assessment based on lessons learned from conducting risk assessments for storage complexes within the PCOR Partnership region. Case studies of these real-world examples, which highlight key aspects of applying the risk assessment process to storage projects, are provided to support the proposed best practices. The development of a best practice requires the execution of multiple projects where the knowledge gained and lessons learned are accumulated over time and integrated to yield a best practice. This development progression is an adaptive management process whereby best practices constantly evolve over time in response to knowledge gained and lessons learned. This document encompasses the current body-of-knowledge and best practices for applying a standardized risk assessment approach within risk management for storage projects. Application of these best practices will provide reliable and consistent standards for identifying project-related risks, analyzing the probabilities and potential impacts of these risks, evaluating which risks require treatment, and determining priority for treatment implementation. These best practices will continue to evolve and be refined over time as commercialization of the CO 2 storage industry proceeds.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Precision and accuracy of magnetic resonance imaging for lobar classification of benign prostatic hyperplasia

Purpose: To validate the application of a magnetic resonance imaging (MRI)-based lobar classification of benign prostatic hyperplasia (BPH) for use in research and clinical management. Methods: Two radiologists with 5 and 11 years post-fellowship experience were trained in the lobar classification of BPH using an internally developed atlas of prostate anatomy with example MRI images edited by a third senior radiologist designated as the “administrator” of the study. A study population of 140 patients referred to a tertiary academic medical center with known or suspected prostate cancer was selected by the administrator to test the interrater reliability (IRR; precision) of the classification as well as accuracy of the two readers compared to the administrator as the “gold” standard. The intrarater reliability of repeat readings of the administrator was also examined. Percentage of agreement, proportion of agreement, and Cohen’s κ were applied. This was a retrospective IRB-approved study. Results: IRR (precision) between the two interpreting radiologists was 64% agreement, corresponding to unweighted κ of 0.52. Composite proportion of agreement across all BPH types (categories) for interpreting radiologists was 0.67. Observer accuracy was 62% agreement, unweighted κ 0.49, for observer 1 and 67%, unweighted κ 0.58, for observer 2. Intrarater reliability for the administrator was 87% agreement, unweighted κ 0.81 with composite proportion of agreement across all categories of 0.87. Conclusions: MRI lobar classification of BPH is a reproducible and reliable tool for research and clinical applications.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2022

Methods—A Practical Approach to the Reversible Hydrogen Electrode Scale

Accurately quantifying applied potential is important to ensuring the comparability, accuracy, and precision of electrochemical studies. Reference electrodes (REs) enable knowledge/determination of the applied potential at electrodes in electrochemical systems. Ultimately, the choice of RE will depend on the particular requirements of a given electrochemical system, however, we note it is imperative to ensure the accuracy of the RE potential and its proper translation to a standardized scale. In this work, we highlight that while there are many commercially available REs, these must be experimentally calibrated to a reliable and practical standard potential scale, for instance the reversible hydrogen electrode (RHE) scale for aqueous systems. With representative data, we provide streamlined instructions on how to calibrate any RE to the RHE scale. We also provide guidance to mitigate and/or avoid possible electrolyte contamination issues arising from REs. Moreover, we offer a step-by-step guide on how to build a practical RHE RE, which may be a suitable and desirable option in certain applications. Our work emphasizes the need for the continuous adoption of standardized reference potential scales and demonstrates the versatility of the RHE scale, particularly in aqueous electrochemistry.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1991

An Outlook for the Twenty First Century as to Launch Operations, Facilities, and Systems

A discussion of launch systems for the 21st century is presented. The following launch systems are mentioned: the European Ariane family; the Japanese H-1 and H-2; the U.S.'s Titan, Delta, Atlas, and Space Shuttle; the Chinese Long March 4; and the USSR's Mir, Proton, and Zenit. Systems currently under investigation, including the Assured Crew Return Vehicle, Personnel Launch Systems, and Single Stage to Orbit (SSTO), are discussed. Automated operations, low Earth orbit, and reliability are addressed. Standards that were acceptable for ballistic missiles will not be acceptable for future launch vehicles. The achievement of significantly higher levels of reliability is seen as the challenge.

Loftus, Joseph P., Jr.↗
NASA NTRS2016

ASTM Committee C28: International Standards for Properties and Performance of Advanced Ceramics, Three Decades of High-quality, Technically-rigorous Normalization

Physical and mechanical properties and performance of advanced ceramics and glasses are difficult to measure correctly without the proper techniques. For over three decades, ASTM Committee C28 on Advanced Ceramics, has developed high quality, rigorous, full-consensus standards (e.g., test methods, practices, guides, terminology) to measure properties and performance of monolithic and composite ceramics that may be applied to glasses in some cases. These standards testing particulars for many mechanical, physical, thermal, properties and performance of these materials. As a result these standards provide accurate, reliable, repeatable and complete data. Within Committee C28 users, producers, researchers, designers, academicians, etc. have written, continually updated, and validated through round-robin test programs, nearly 50 standards since the Committees founding in 1986. This paper provides a retrospective review of the 30 years of ASTM Committee C28 including a graphical pictogram listing of C28 standards along with examples of the tangible benefits of advanced ceramics standards to demonstrate their practical applications.

properties↗
NASA NTRS2016

International Standards for Properties and Performance of Advanced Ceramics - 30 years of Excellence

Mechanical and physical properties/performance of brittle bodies (e.g., advanced ceramics and glasses) can be difficult to measure correctly unless the proper techniques are used. For three decades, ASTM Committee C28 on Advanced Ceramics, has developed numerous full-consensus standards (e.g., test methods, practices, guides, terminology) to measure various properties and performance of a monolithic and composite ceramics and coatings that, in some cases, may be applicable to glasses. These standards give the "what, how, how not, why, why not, etc." for many mechanical, physical, thermal, properties and performance of advanced ceramics. Use of these standards provides accurate, reliable, repeatable and complete data. Involvement in ASTM Committee C28 has included users, producers, researchers, designers, academicians, etc. who write, continually update, and validate through round robin test programmes, more than 45 standards in the 30 years since the Committee's inception in 1986. Included in this poster is a pictogram of the ASTM Committee C28 standards and how to obtain them either as i) individual copies with full details or ii) a complete collection in one volume. A listing of other ASTM committees of interest is included. In addition, some examples of the tangible benefits of standards for advanced ceramics are employed to demonstrate their practical application.

composites↗
NASA NTRS2003

Optimization Based Efficiencies in First Order Reliability Analysis

This paper develops a method for updating the gradient vector of the limit state function in reliability analysis using Broyden's rank one updating technique. In problems that use commercial code as a black box, the gradient calculations are usually done using a finite difference approach, which becomes very expensive for large system models. The proposed method replaces the finite difference gradient calculations in a standard first order reliability method (FORM) with Broyden's Quasi-Newton technique. The resulting algorithm of Broyden updates within a FORM framework (BFORM) is used to run several example problems, and the results compared to standard FORM results. It is found that BFORM typically requires fewer functional evaluations that FORM to converge to the same answer.

Peck, Jeffrey A.↗
DOE OSTI2015

Framework for Modeling High-Impact, Low-Frequency Power Grid Events to Support Risk-Informed Decisions

Natural and man-made hazardous events resulting in loss of grid infrastructure assets challenge the electric power grid’s security and resilience. However, the planning and allocation of appropriate contingency resources for such events requires an understanding of their likelihood and the extent of their potential impact. Where these events are of low likelihood, a risk-informed perspective on planning can be problematic as there exists an insufficient statistical basis to directly estimate the probabilities and consequences of their occurrence. Since risk-informed decisions rely on such knowledge, a basis for modeling the risk associated with high-impact low frequency events (HILFs) is essential. Insights from such a model can inform where resources are most rationally and effectively expended. The present effort is focused on development of a HILF risk assessment framework. Such a framework is intended to provide the conceptual and overarching technical basis for the development of HILF risk models that can inform decision makers across numerous stakeholder sectors. The North American Electric Reliability Corporation (NERC) 2014 Standard TPL-001-4 considers severe events for transmission reliability planning, but does not address events of such severity that they have the potential to fail a substantial fraction of grid assets over a region, such as geomagnetic disturbances (GMD), extreme seismic events, and coordinated cyber-physical attacks. These are beyond current planning guidelines. As noted, the risks associated with such events cannot be statistically estimated based on historic experience; however, there does exist a stable of risk modeling techniques for rare events that have proven of value across a wide range of engineering application domains. There is an active and growing interest in evaluating the value of risk management techniques in the State transmission planning and emergency response communities, some of this interest in the context of grid modernization activities. The availability of a grid HILF risk model, integrated across multi-hazard domains which, when interrogated, can support transparent, defensible and effective decisions, is an attractive prospect among these communities. In this report, we document an integrated HILF risk framework intended to inform the development of risk models. These models would be based on the systematic and comprehensive (to within scope) characterization of hazards to the level of detail required for modeling risk, identification of the stressors associated with the hazards (i.e., the means of impacting grid and supporting infrastructure), characterization of the vulnerability of assets to these stressors and the probabilities of asset compromise, the grid’s dynamic response to the asset failures, and assessment of subsequent severities of consequence with respect to selected impact metrics, such as power outage duration and geographic reach. Specifically, the current framework is being developed to;1. Provide the conceptual and overarching technical paradigms for the development of risk models; 2. Identify the classes of models required to implement the framework - providing examples of existing models, and also identifying where modeling gaps exist; 3. Identify the types of data required, addressing circumstances under which data are sparse and the formal elicitation of informed judgment might be required; and 4. Identify means by which the resultant risk models might be interrogated to form the necessary basis for risk management.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS2003

Overview of the SAE G-11 RMSL (Reliability, Maintainability, Supportability, and Logistics) Division Activities and Technical Projects

The SAE G-11 RMSL (Reliability, Maintainability, Supportability, and Logistics) Division activities include identification and fulfillment of joint industry, government, and academia needs for development and implementation of RMSL technologies. Four Projects in the Probabilistic Methods area and two in the area of RMSL have been identified. These are: (1) Evaluation of Probabilistic Technology - progress has been made toward the selection of probabilistic application cases. Future effort will focus on assessment of multiple probabilistic softwares in solving selected engineering problems using probabilistic methods. Relevance to Industry & Government - Case studies of typical problems encountering uncertainties, results of solutions to these problems run by different codes, and recommendations on which code is applicable for what problems; (2) Probabilistic Input Preparation - progress has been made in identifying problem cases such as those with no data, little data and sufficient data. Future effort will focus on developing guidelines for preparing input for probabilistic analysis, especially with no or little data. Relevance to Industry & Government - Too often, we get bogged down thinking we need a lot of data before we can quantify uncertainties. Not True. There are ways to do credible probabilistic analysis with little data; (3) Probabilistic Reliability - probabilistic reliability literature search has been completed along with what differentiates it from statistical reliability. Work on computation of reliability based on quantification of uncertainties in primitive variables is in progress. Relevance to Industry & Government - Correct reliability computations both at the component and system level are needed so one can design an item based on its expected usage and life span; (4) Real World Applications of Probabilistic Methods (PM) - A draft of volume 1 comprising aerospace applications has been released. Volume 2, a compilation of real world applications of probabilistic methods with essential information demonstrating application type and timehost savings by the use of probabilistic methods for generic applications is in progress. Relevance to Industry & Government - Too often, we say, 'The Proof is in the Pudding'. With help from many contributors, we hope to produce such a document. Problem is - not too many people are coming forward due to proprietary nature. So, we are asking to document only minimum information including problem description, what method used, did it result in any savings, and how much?; (5) Software Reliability - software reliability concept, program, implementation, guidelines, and standards are being documented. Relevance to Industry & Government - software reliability is a complex issue that must be understood & addressed in all facets of business in industry, government, and other institutions. We address issues, concepts, ways to implement solutions, and guidelines for maximizing software reliability; (6) Maintainability Standards - maintainability/serviceability industry standard/guidelines and industry best practices and methodologies used in performing maintainability/ serviceability tasks are being documented. Relevance to Industry & Government - Any industry or government process, project, and/or tool must be maintained and serviced to realize the life and performance it was designed for. We address issues and develop guidelines for optimum performance & life.

Singhal, Surendra N.↗
NASA NTRS2008

Low-Light-Shift Cesium Fountain without Mechanical Shutters

A new technique for reducing errors in a laser-cooled cesium fountain frequency standard provides for strong suppression of the light shift without need for mechanical shutters. Because mechanical shutters are typically susceptible to failure after operating times of the order of months, the elimination of mechanical shutters could contribute significantly to the reliability of frequency standards that are required to function continuously for longer time intervals. With respect to the operation of an atomic-fountain frequency standard, the term "light shift" denotes an undesired relative shift in the two energy levels of the atoms (in this case, cesium atoms) in the atomic fountain during interrogation by microwaves. The shift in energy levels translates to a frequency shift that reduces the precision and possibly accuracy of the frequency standard. For reasons too complex to describe within the space available for this article, the light shift is caused by any laser light that reaches the atoms during the microwave- interrogation period, but is strongest for near-resonance light. In the absence of any mitigating design feature, the light shift, expressed as a fraction of the standard fs frequency, could be as large as approx. 2 x 10(exp -11), the largest error in the standard. In a typical prior design, to suppress light shift, the intensity of laser light is reduced during the interrogation period by using a single-pass acoustooptic modulator to deflect the majority of light away from the main optical path. Mechanical shutters are used to block the remaining undeflected light to ensure complete attenuation. Without shutters, this remaining undeflected light could cause a light shift of as much as .10.15, which is unacceptably large in some applications. The new technique implemented here involves additionally shifting the laser wavelength off resonance by a relatively large amount (typically of the order of nanometers) during microwave interrogation. In this design, when microwave interrogation is not underway, the atoms are illuminated by a slave laser locked to the lasing frequency of a lower power master laser.

Enzer, Daphna↗
NASA NTRS1982

Lamp reliability studies for improved satellite rubidium frequency standard

In response to the premature failure of Rb lamps used in Rb atomic clocks onboard NAVSTAR GPS satellites experimental and theoretical investigations into their failure mechanism were initiated. The primary goal of these studies is the development of an accelerated life test for future GPS lamps. The primary failure mechanism was identified as consumption of the lamp's Rb charge via direct interaction between Rb and the lamp's glass surface. The most effective parameters to accelerate the interaction between the Rb and the glass are felt to be RF excitation power and lamp temperature. Differential scanning calorimetry is used to monitor the consumption of Rb within a lamp as a function of operation time. This technique yielded base line Rb consumption data for GPS lamps operating under normal conditions.

Frueholz, R. P.↗
NASA NTRS2003

Overview of Probabilistic Methods for SAE G-11 Meeting for Reliability and Uncertainty Quantification for DoD TACOM Initiative with SAE G-11 Division

The SAE G-11 RMSL Division and Probabilistic Methods Committee meeting during October 6-8 at the Best Western Sterling Inn, Sterling Heights (Detroit), Michigan is co-sponsored by US Army Tank-automotive & Armaments Command (TACOM). The meeting will provide an industry/government/academia forum to review RMSL technology; reliability and probabilistic technology; reliability-based design methods; software reliability; and maintainability standards. With over 100 members including members with national/international standing, the mission of the G-11's Probabilistic Methods Committee is to "enable/facilitate rapid deployment of probabilistic technology to enhance the competitiveness of our industries by better, faster, greener, smarter, affordable and reliable product development."

Singhal, Surendra N.↗