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At least 1,099 records · Page 61

Sierra/SolidMechanics 4.46 Example Problems Manual

Presented in this document are tests that exist in the Sierra/SolidMechanics example problem suite, which is a subset of the Sierra/SM regression and performance test suite. These examples showcase common and advanced code capabilities. A wide variety of other regression and verification tests exist in the Sierra/SM test suite that are not included in this manual.

97 MATHEMATICS AND COMPUTING↗

Proceedings of the 7th US/German Workshop on Salt Repository Research, Design, and Operation

The 7th US/German Workshop on Salt Repository Research, Design, and Operation was held in Washington, DC on September 7-9, 2016. Over fifty participants representing governmental agencies, internationally recognized salt research groups, universities, and private companies helped advance the technical basis for salt disposal of radioactive waste. Representatives from several United States federal agencies were able to attend, including the Department of Energy's Office of Environmental Management and Office of Nuclear Energy, the Environmental Protection Agency, the Nuclear Regulatory Commission, and the Nuclear Waste Technical Review Board. A similar representation from the German ministries showcased the covenant established in a Memorandum of Understanding executed between the United States and Germany in 2011. The US/German workshops' results and activities also contribute significantly to the Nuclear Energy Agency Salt Club repository research agenda.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Final Scientific Findings Report- Hydro Research Foundation- Research Awards Program

The Research Awards Program was established in 2014 by the Hydro Research Foundation (Foundation) to support research efforts for the hydropower industry. Using the previously funded Fellowship Program that ran from 2010-2015, the Research Awards Program (RAP or program) captured the lessons learned from the Fellowship program and fine-tuned a nation-wide graduate level research program to support innovation, research and workforce development. The RAP was funded through a $2 million-dollar grant through the Department of Energy’s Water Power Program within the Energy Efficiency and Renewable Energy office (DOE). This award made possible, 33 research projects by 32 students from 21 universities in 11 states. The grant widely engaged the industry by providing the opportunity to work with 25 organizations as well as 63 students and advisors. The funded research focused on a topic list selected by industry and worked to cover a breadth of research needs across many disciplines, basins and types of hydropower issues. The funded work, answered pressing research needs in the fields of the following disciplines; civil engineering, mechanical engineering, environmental engineering, electrical engineering, geography, fisheries, wildlife, water resources, geology, energy science and materials innovation. The Foundation estimates that 116 individuals benefited from this research through either direct mentorship (42), research (32), overseeing the research (31), partnerships (7) and the day-to-day management of the program (4). This investment by DOE showcases how private-public partnerships can leverage limited funds to create a wide range of research products. The project objective was to build on the successful Fellowship Program to develop and execute the RAP on a national level. The program sought to provide competitively awarded hydropower-related graduate-level research awards. The intent of the RAP was to support beneficial, innovative research related to conventional or pumped-storage hydropower. It also sought to stimulate interest among students and universities in this research arena and provide students with a foundation for productive careers within the hydropower industry. The outcome was 33 research findings with 100% of proposed research completed. In addition, 87% of students chose to either join the hydropower industry or continue their hydropower related research at their universities. These research findings advanced the understanding of pressing research topics within the hydropower industry and met the objective of the funding. An ancillary benefit the program identified through this funding was, not only did 63 students and advisors work on hydropower within the academia space, but now there are more professors and students teaching hydropower at the university level. The program saw an addition of 12 new professors, teaching assistants, and graduate researchers continuing to simulate interest in hydropower. Another interesting outcome is that during this grant funding, the program saw alumni of the predecessor program, who are now professors, applying for the RAP with their students. A unique element of this funding is there was significant cost-share provided by host universities, who did not charge facilities and administration overhead to the student’s research awards. In addition, each university provided laboratories, computing capacity and research facilities to support the research which is extraordinarily unique to grant funding at the university level. The total cost share exceeded 30% of the total grant cost. The funding clearly reached many sectors of the industry to provide helpful work and continue building hydropower’s next generation of innovation and workforce. The Foundation has established a broad network of universities interested and engaged in hydropower. The work was supported by the hydropower industry through donations of meeting space, conference registrations, in-kind contributions, mentorship and support of students. The Foundation would recommend finding a vehicle to further advance programs like the graduate level research through competitions, competitively funded awards and student research. It will take many universities to advance hydropower’s most pressing challenges. To let a program like the RAP dwindle away would incapacitate research at universities.

13 HYDRO ENERGY↗

Development of harmonic balance capability for Charon

We report on the development of a frequency domain method of analysis in the Panzer foundation of Charon. We first present a harmonic balance approach for calculating the frequency-domain response (in its weak form) of a non-linear system of partial differential equations (PDEs). Our approach is anemable to adaptation of Charon's transient PDE models for frequency domain analysis. We make an observation that allows us to analyze either small-signal or large-signal responses with minimal specialization of the algorithm. We conclude by confirming our small- and large-signal analyses of a transient, linear Helmholtz equation by comparing its analytic solution to our results. We include figures from a sequence of non-linear perturbations of this system, showcasing the fact that, when the non-linearities are insignificant, the small- and large-signal analyses obtain similar solutions. On the other hand, we depict the inadequacy of a small-signal analysis to accurately capture the response in the presence of a large non-linearity, and underscore the requirement to employ a large-signal analysis for modelling highly non-linear systems.

97 MATHEMATICS AND COMPUTING↗

Generation and application of multivariate polynomial quadrature rules

The search for multivariate quadrature rules of minimal size with a specified polynomial accuracy has been the topic of many years of research. Finding such a rule allows accurate integration of moments, which play a central role in many aspects of scientific computing with complex models. The contribution of this paper is twofold. First, we provide novel mathematical analysis of the polynomial quadrature problem that provides a lower bound for the minimal possible number of nodes in a polynomial rule with specified accuracy. We give concrete but simplistic multivariate examples where a minimal quadrature rule can be designed that achieves this lower bound, along with situations that showcase when it is not possible to achieve this lower bound. Our second main contribution comes in the formulation of an algorithm that is able to efficiently generate multivariate quadrature rules with positive weights on non-tensorial domains. Our tests show success of this procedure in up to 20 dimensions. We test our method on applications to dimension reduction and chemical kinetics problems, including comparisons against popular alternatives such as sparse grids, Monte Carlo and quasi Monte Carlo sequences, and Stroud rules. The quadrature rules computed in this paper outperform these alternatives in almost all scenarios.

97 MATHEMATICS AND COMPUTING↗

Advanced Research Projects Agency - Energy Annual Report for FY 2014

This report presents a summary of the activities of the Advanced Research Projects Agency-Energy (ARPA-E) during Fiscal Year 2014 (FY2014). In FY2014, ARPA-E issued funding solicitations and selected projects for three new programs covering a broad array of energy technologies, including: 27 million dollars to develop next-generation power switching devices that improve energy efficiency in a wide range of applications; 30 million dollars for hybrid solar energy beyond current photovoltaic (PV) and concentrated solar power (CSP) technologies; and 33 million dollars for electrochemical technologies to enable low-cost distributed power generation. ARPA-E released three additional funding opportunities in FY2014 with project selections that were ultimately announced in FY2015. These programs include: 30 million dollars for localized heating and cooling devices to expand temperature ranges within buildings reducing energy consumption; 30 million dollars for low-cost, high-sensitivity systems to detect and measure methane emissions; and 30 million dollars for low-cost tools to aid in the future development of fusion power. ARPA-E also continued the use of a rolling open solicitation to quickly support innovative applied energy research that has the potential to lead to new focused programs. In addition to these new programs, ARPA-E hosted the fifth annual Energy Innovation Summit from February 24-26, 2014. The Summit brought together leaders from academia, government, and business to discuss the foremost energy issues, showcase the latest technology innovations, and cultivate relationships to help advance cutting-edge technologies to market. The event drew over 2,100 attendees and featured over 120 speakers and keynote addresses. At the Summit, ARPA-E announced at least 24 ARPA-E project teams that have formed new companies and more than 16 ARPA-E projects, which have partnered with other government agencies for further development. Additionally, 22 ARPA-E projects have attracted more than 625 million dollars in private-sector follow-on funding after ARPA-E’s investment of approximately 95 million dollars. Lastly, ARPA-E continued to focus on providing awardees with practical training and critical business information as part of the Agency’s Technology-to-Market program. This support equips projects with a clear understanding of market needs to guide technical development and help projects succeed the marketplace.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Sierra/SolidMechanics 4.54 Example Problems Manual

Presented in this document are tests that exist in the Sierra/SolidMechanics example problem suite, which is a subset of the Sierra/SM regression and performance test suite. These examples showcase common and advanced code capabilities. A wide variety of other regression and verification tests exist in the Sierra/SM test suite that are not included in this manual.

97 MATHEMATICS AND COMPUTING↗

Smarter Grid Solutions | National Renewable Energy Laboratory: Active Management Integration: June 2015 - November 2016

This report presents the project results for the NREL INTEGRATE demonstration project: Active Network Management (ANM) Integration. Consistent with the INTEGRATE program's objective of increasing the grid's clean energy hosting capacity and providing grid services in a holistic manner, the project demonstrated the use of ANM to enable very high penetrations of solar PV and wind energy systems. Results obtained using a representative North American distribution system showed ANM's autonomous distributed control doubled the interconnected wind and solar systems by managing thermal and voltage constraints in real-time. These generators flexibly interconnected to the grid via ANM's end-to-end control architecture, and were managed and coordinated with other smart distributed energy resources (DER; e.g. EVs, battery ESS, controllable load) to unlock the grid's dynamic hosting capacity. As a smart grid application to standardize grid integration of diverse renewable generation sources, ANM provides the industry with a scalable, cost-effective alternative to traditional transmission and distribution (T&D) reinforcements. This project considered three use cases of the application of ANM: a Smart Home demonstration of ANM control of residential scale devices (PV, EV, and battery ESS); a Smart Campus demonstration of high penetration megawatt-scale DER (PV, EVs, battery ESS, and controllable load) behind a single point-of-common-coupling (PCC), and a Smart Distribution demonstration that combined prior use cases along with additional community/utility-scale DER at very high aggregate penetration levels. The Smart Distribution use case provided an integrated perspective of ANM across all distribution grid DER device scales (incorporating aggregated Smart Homes and the Smart Campus) in order to showcase how these devices can support smart grid services to manage DER related constraints in a safe and reliable manner; and likewise how ANM integrates with grid modernization initiatives. The ANM system was deployed in NREL's Energy Systems Integration Facility (ESIF), and project industry advisors attended an on-site demonstration and a set of workshops in order to review project outcomes and evaluate the relevance of ANM for increasing the grid hosting capacity. The outcomes of this effort include an assessment of opportunities for field deployment of ANM to address existing interconnection challenges, as well as consolidating project advisor suggestions for investment in ANM and potential future pilots for more advanced schemes.

24 POWER TRANSMISSION AND DISTRIBUTION↗

Evaluation of Hydrogen Production Feasibility for a Light Water Reactor in the Midwest

Increased electricity production from renewable energy resources coupled with low natural gas prices has caused existing light-water reactor (LWRs) to experience ever diminishing returns from the electricity market. Via partnership among Idaho National Laboratory (INL), The National Renewable Energy Laboratory (NREL), Argonne National Laboratory (ANL), Exelon, and Fuel Cell Energy a techno-economic analysis on the viability of retrofitting existing pressurized water reactors (PWRs) to produce hydrogen (H2) via high temperature steam electrolysis (HTSE) has been conducted. Such integration would allow nuclear facilities to expand into additional markets that may be more profitable in the long-term. To accommodate such an integration, a detailed analysis of HTSE process operation, requirements, and flexibility was conducted. Technical analysis includes proposed nuclear system control scheme modifications to allow dynamic operation of the HTSE via both thermal and electrical connection to the nuclear plant. High fidelity Modelica simulations showcase the viability of such control schemes. However, due to limited knowledge of solid oxide fuel cell (SOFC) stack degradation due to thermal gradients; thermal cycling of the HTSE was not included. Therefore, the control schemes proposed are only utilized to re-distribute steam at startup and only the portion of electricity utilized in the electrolyzers is cycled. From the detailed analysis of the nuclear integration and the HTSE process design, a comprehensive cost estimation was conducted in the APEA and H2A models to elucidate capital and operational costs associated with the production, compression, and distribution of hydrogen from a nuclear facility. Alongside this costing analysis, market analyses were conducted by NREL and ANL on the electric and hydrogen markets respectively in the PJM interconnect. Utilizing the electricity data market projections in the PJM interconnect from NREL and hydrogen demand/pricing projections from ANL a five variable sweep over component capacities, discount rates, and hydrogen pricing was completed using the stochastic framework RAVEN (Risk Analysis Virtual ENVironment) through its resource dispatch plugin HERON (Heuristic Energy Resource Optimization Network). Each combination of variables was evaluated stochastically four times over a seventeen year timespan from 2026-2042 (inclusive) to determine the most economically advantageous solution. Following the five variable sweep an optimization was conducted about the best sweep point to determine optimal component sizing and setpoints. Results suggest positive gain is achievable at all projected hydrogen market pricing levels and at all discount rates. However, exact component sizing and net returns vary based on these values and if incorrect sizing is selected; major net losses can occur. The optimal result occurred with set points as follows: high hydrogen prices, the largest possible HTSE unit in the sweep set at 7.47 kg/sec [645.4 tpd], a contractual hydrogen market agreement 7.29 kg/sec [629.8 tpd], and a hydrogen storage size 115,188 kg. The analysis suggested that with a discount rate of 8%, a ΔNPV = 1.2 billion over the seventeen year span can be achieved. The results illuminate that by operating in multiple markets the nuclear facility is capable of avoiding sale of electricity during times of low electricity market pricing, while maintaining the ability to capitalize on the high electricity market pricing. It should be noted that the analysis conducted in this report is a differential cash flow analysis and as such does not present profit levels. Instead it highlights the net benefit between building and competing in the hydrogen market utilizing nuclear facilities and conducting business as usual in the electricity markets. Additionally, results presented in this report exhibit conservatism due to four key assumptions: Given the limited knowledge on SOFC stack degradation due to thermal gradients the high temperature steam electrolysis plant is not allowed to thermally cycle. This limitation decreases electricity generation capacity in the nuclear plant, reducing capacity payments and the maximum output to the electrical grid. This analysis considers building a separate hydrogen pipeline for use in the nuclear facility. Research is currently being conducted to determine if existing natural gas pipelines can accommodate direct hydrogen injection. If hydrogen can be integrated into existing natural gas pipelines then a capital savings of ~$19,000,000 per kg/sec [1 kg/sec = 86.4 tpd] of installed HTSE capacity could be realized. Fast transients in the electric grid are typically served by flywheels and electric batteries. With electrolysis only operation the nuclear plant can flex its electricity just as quickly. However, for this analysis, the ancillary services market has been neglected. Should the nuclear plant have the ability to operate in the ancillary services market during periods when it is producing hydrogen, an additional substantial income stream that would increase overall system profitability could be considered. Subsidies for non-emitting generation technologies are not introduced in the cash flow analysis, but instead are completed assuming zero subsidies. Profitability is based solely on electricity pricing. Electric pricing is assumed to never go negative. Instead, it is assumed overall system curtailment by the Independent System Operator (ISO) will occur in such a manner that pricing remains at or above zero. This assumption inflates the “business as usual” scenario, thus decreasing the ΔNPV calculated. If negative pricing scenarios continue to occur as they do today, one would expect a further increase in ΔNPV. Overall, results advocate that, through market diversification, nuclear power plants have the potential to substantially increase current profit margins, increase market penetration, and ultimately solidify their place as a mainstay in energy production.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Entrepreneurial Community Feedback on the National Laboratory Accelerator Pitch Competition

Twelve DOE National Labs came together for a Pitch Event as the culmination of the National Lab Accelerator Program. The event was a showcase of Department of Energy innovation where National Laboratory scientists pitched to seasoned investors in an exciting completion. Approximately 60 people attended the September 25th event, bringing together National Lab researchers, technology transfer professionals and the business investment community for a day of technology and business model evaluation and valuable networking.

99 GENERAL AND MISCELLANEOUS↗

Photovoltaic Inverter Reliability Assessment

As the price of PV modules drops, the price of power electronics become more important. Power electronics now constitute 8%-12% of the total lifetime PV cost. As of 2010, the inverter and associated power conditioning components accounted for $\$0.25$/W, well above the DOE benchmark of $\$0.12$/W by 2020. As efforts to reduce PV module costs yield diminishing returns, the importance of understanding and reducing inverter costs becomes an increasingly critical and cost-effective investment toward achieving the DOE SunShot goals. With this in view, this report showcases and describes an approach to help assess and predict the reliability of photovoltaic (PV) inverters. To predict the reliability, thermal cycling is considered as a prominent stressor in the inverter system. To evaluate the impacts of thermal cycling, a detailed linearized model of the PV inverter is developed along with controllers. This research also develops models and methods to compute the losses of the power electronics switches and other components in a PV inverter. The losses are then used to estimate the junction and heat sink temperature. The model is verified by developing an in-house inverter. Additionally, to assess the scalability of the research, the hardware inverter is placed inside a thermal chamber to verify the losses for different ambient temperatures. After the verification of the model, a reduced-order model of the inverter is implemented to translate the profile of ambient temperature and solar irradiance into the profile of junction temperatures of the switches. The estimated junction temperature data are used to identify inverter reliability indices and predict the useful lifetime of the inverter system. After developing the models to predict the useful lifetime of the system, the impact of reactive power on the overall reliability of the system will be studied. The first chapter involves the motivation behind the research on assessing the reliability of PV inverters. The inverter power stage and controller design of the power converter used in this research is also explained in detail in this chapter. The second chapter presents the various losses of the power converter system and the translation of power loss into temperature increase with thermal modeling. The results of the loss modeling and the thermal modeling are also explained in detail in this chapter. The third chapter involves implementing the reduced-order model to translate the mission profile of ambient temperature and solar irradiance into profile of the junction temperatures of the switches. The final chapter involves identifying reliability indices, which are of interest for this system to predict the remaining useful life of the system, and concludes with the impact of reactive power on the overall reliability of the inverter system.

14 SOLAR ENERGY↗

Drag Coefficient Analysis of Arbitrary Fragment Geometry with Emphasis on Meshing Sensitivity Studies.

This report characterizes Mach number effects in the hypersonic range from Mach 3 to Mach 7 for an arbitrary, computationally generated fragment. Force and moment coefficients in the x, y, z direction were successfully obtained and resulting trends were compared with theoretical expectations. Three orientations were tested in the form of unit vectors: [1,0,0], [0,1,0], and [0,0,1]; these represent the i, j, k principle axes. The final results ultimately showcased a trend very similar to that shown in previous literature — drag coefficients for a given orientation decreased with increasing Mach number by a very small amount in the hypersonic range. It was therefore concluded that the aerodynamic quantities used to obtain the fragment trajectory at low hypersonic Mach numbers (such as Mach 3) can be used to characterize the aerodynamic qualities at higher hypersonic Mach numbers (Mach 5, 7) with a reasonably small margin. A sensitivity study was also conducted which ultimately defined drag effects as a result of changing grid spacing and normal extrusion parameters for the unstructured tetrahedral mesh used in the simulation. Further work can be done in the form of experimental validation, specifically with regards to wind tunnels and ballistic range testing. Error can be reduced by testing more mesh variabilities and capturing a larger amount of fragment orientations. The results for force and moment characteristics dependent on meshing parameters and high Mach numbers are satisfactory and consistent with expected trends.

42 ENGINEERING↗

Sierra/SolidMechanics 4.46 Example Problems Manual

Presented in this document are tests that exist in the Sierra Solid Mechanics example problem suite. The purpose of these examples is to showcase common and advanced code capabilities. Note that many other regression and verification tests exist in the Sierra/SM test suite that have not been included in this manual.

97 MATHEMATICS AND COMPUTING↗

Magnetic Microcalorimeter (MMC) Gamma-Ray Detectors with Ultra-High Energy Resolution. Comprehensive Technology Readiness Assessment

Magnetic Microcalorimeter (MMC) gamma ray detectors have demonstrated very high energy resolution of 38 eV FWHM for gamma ray energies below 100 keV. This is an order or magnitude better than conventional HPGe detector and can remove most line-overlap problems in NDA by gamma spectroscopy below ~130 keV. Unlike superconducting transition edge sensors (TESs), MMCs have a reproducible and almost perfectly linear response, which greatly simplifies adding spectra from different detector pixels and reduces systematic errors in quantitative assays. The instrument is currently at TRL-5 but could advance to TRL-6 by improving the signal processing software and using the system for the quantitative analysis of a safeguards sample provided by e.g. the IAEA. Making MMC detectors commercially viable and used more widely then depends on making the technology more reliable, specifically by increasing the device uniformity and yield, and by developing commercial software. This situation is often only half-jokingly referred to as the “valley of death” and could be addressed though the SBIR program. Our collaborators at STAR Cryoelectronics LLC are well qualified to further advance MMC development, and XIA LLC is well-positioned to develop the data acquisition system and write the software for MMC readout. In addition, the advance to TRL-6 would be desirable to increase the visibility and showcase the value of MMC spectrometers, e.g. by placing one of them into the Safeguards Analytical Laboratory (SAL) at the IAEA, whose NDA experts have recently started to show interest in cryogenic detector technology. As a result of this LCP, we also now have an instrument at LLNL that we will use for various applications of MMCs in nuclear safeguards and science. We are confident that as the number of high-profile results increases, so will the interest in and commercial viability of this technology.

42 ENGINEERING↗

Magnetic Microcalorimeter (MMC) Gamma-Ray Detectors with Ultra-High Energy Resolution. Comprehensive Technology Readiness Assessment

Magnetic Microcalorimeter (MMC) gamma ray detectors have demonstrated very high energy resolution of 38 eV FWHM for gamma ray energies below 100 keV. This is an order or magnitude better than conventional HPGe detector and can remove most line-overlap problems in NDA by gamma spectroscopy below ~130 keV. Unlike superconducting transition edge sensors (TESs), MMCs have a reproducible and almost perfectly linear response, which greatly simplifies adding spectra from different detector pixels and reduces systematic errors in quantitative assays. The instrument is currently at TRL-5 but could advance to TRL-6 by improving the signal processing software and using the system for the quantitative analysis of a safeguards sample provided by e.g. the IAEA. Making MMC detectors commercially viable and used more widely then depends on making the technology more reliable, specifically by increasing the device uniformity and yield, and by developing commercial software. This situation is often only half-jokingly referred to as the “valley of death” and could be addressed though the SBIR program. Our collaborators at STAR Cryoelectronics LLC are well qualified to further advance MMC development, and XIA LLC is well-positioned to develop the data acquisition system and write the software for MMC readout. In addition, the advance to TRL-6 would be desirable to increase the visibility and showcase the value of MMC spectrometers, e.g. by placing one of them into the Safeguards Analytical Laboratory (SAL) at the IAEA, whose NDA experts have recently started to show interest in cryogenic detector technology. As a result of this LCP, we also now have an instrument at LLNL that we will use for various applications of MMCs in nuclear safeguards and science. We are confident that as the number of high-profile results increases, so will the interest in and commercial viability of this technology.

42 ENGINEERING↗

Contingency Contractor Optimization Tool Prototype (Phase 3 Extension- Analyst Tutorial)

This tutorial walks the user through analysis examples using the Contingency Contractor Optimization Tool Prototype. The examples are designed to showcase key capabilities of the tool. The main goal of this tutorial is to provide examples of how to use the tool to perform analyses to those users acting in the analyst role. All examples and locations used in the prototype are fictional, but are intended to be realistic. Users reading this manual are expected to have a basic understanding and familiarity with the Contingency Contractor Optimization Tool Prototype. This tutorial includes scenarios for the occurrence of two wars, Prussia and New Granada.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗

Women in Environmental Science

Despite the prominent role that women have traditionally played in environmental activism and initiatives to promote environmental justice, women’s representation in most environmental science fields remains low. The first environmental laws in the U.S., established in the 60’s and 70’s, were propelled by movements evolved out of male dominated scientific professions, mainly engineering. To this day, environmental fields are still perceived as not open to women. Yet the field being so broad, it offers many opportunities for women scientists to contribute to the advancement of science and technology needed to address the most pressing environmental issues. To this end, the Society for Industrial Microbiology and Biotechonology organized a session at its 2019 General Meeting entitled Women in Environmental Science that showcased the work of women leading efforts in environmental fields. The session was convened by Dr. Gemma Reguera (Michigan State University) and Dr. Arpita Bose (Washington University in St. Louis) and included 4 additional speakers whose work spans basic and applied environmental research yet impacts discovery-driven science, technology development, science policy and communication, in addition to environmental advocacy and stewardship. The talks highlighted the career path of women-led teams whose research and professional activities are contributing to the development of “biobased solutions to DOE mission challenges in energy and environment”.

54 ENVIRONMENTAL SCIENCES↗

Report on local data recovery approaches suitable for weather and climate prediction (Deliverable 1.3) (V.1.0)

Numerical weather and climate prediction rates as one of the scientific applications whose accuracy improvements greatly depend on the growth of the available computing power. As the number of cores in top computing facilities pushes into the millions, increasing average frequency of hardware and software failures forces users to review their algorithms and systems in order to protect simulations from breakdown. This report surveys approaches for fault-tolerance in numerical algorithms and system resilience in parallel simulations from the perspective of numerical weather and climate prediction systems. A selection of existing strategies is analyzed, featuring interpolation-restart and compressed checkpointing for the numerics, in-memory checkpointing, user-level failure mitigation-based and backup-based methods for the systems. Numerical examples showcase the performance of the techniques in addressing faults, with particular emphasis on iterative solvers for linear systems, a staple of atmospheric fluid flow solvers. The potential impact of these strategies is discussed in relation to current development of numerical weather prediction algorithms and systems towards the exascale. Trade-offs between performance, efficiency and effectiveness of resiliency strategies are analyzed and some recommendations outlined for future developments.

97 MATHEMATICS AND COMPUTING↗