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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 1,045 records · Page 58
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Preservation of the High Quality Factor and Accelerating Gradient of Nb3Sn-coated Cavity During Pair Assembly

Two CEBAF 5-cell accelerator cavities have been coated with Nb3Sn film using the vapor diffusion technique. One cavity was coated in the Jefferson Lab Nb3Sn cavity coating system, and the other in the Fermilab Nb3Sn coating system. Both cavities were measured at 4 K and 2 K in the vertical dewar test in each lab and then assembled into a cavity pair at Jefferson Lab. Previous attempts to assemble Nb3Sn cavities into a cavity pair degraded the superconducting properties of Nb3Sn-coated cavities. This contribution discusses the efforts to identify and mitigate the pair assembly challenges and will present the results of the vertical tests before and after pair assembly. Notably, one of the cavities reached the highest gradient above 80 mT in the vertical test after the pair assembly.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

A Privacy Preserving Distributed Model Identification Algorithm for Power Distribution Systems: Preprint

Distributed control/optimization is a promising approach for network systems due to its advantages over centralized schemes, such as robustness, cost-effectiveness, and improved privacy. However, distributed methods can have drawbacks, such as slower convergence rates due to limited knowledge of the overall network model. Additionally, ensuring privacy in the communication of sensitive information can pose implementation challenges. To address this issue, we propose a distributed model identification algorithm that enables each agent to identify the sub-model that characterizes the relationship between its local control and the overall system outputs. The proposed algorithm maintains the privacy of local agents by only communicating through dummy variables. We demonstrate the efficacy of our algorithm in the context of power distribution systems by applying it to the voltage regulation of a modified IEEE distribution system. The proposed algorithm is well-suited to the needs of power distribution controls and offers an effective solution to the challenges of distributed model identification in network systems.

data-driven modeling↗
DOE OSTI2024

Privacy-Preserving Control of Partitioned Energy Resources

Distributed energy resources are an increasingly important part of the electric grid. We examine the problem of partitioning a distributed energy resource among many users while providing privacy to them. In this model, clients can send requests to a server, the server can verify that the requests are valid and aggregate them, but it cannot see the actual values in the requests. Without privacy, each user is forced to reveal their daily schedule or energy use. Energy resources add a novel challenge that prior systems do not address: they require verifying limits on private power (a rate over time) and energy (a sum) values. Furthermore, the cryptographic mechanisms must run on embedded energy control systems. We describe Weft, a novel cryptographic system that verifies both power (rate) and energy (integral) constraints on private client values and aggregates them. The key insight behind the approach is to rely on additively homomorphic secret shares, which allows servers to compute sums from rates. We present 3 cryptographic proof systems with different system trade-off for embedded systems: bit-splitting proofs minimize memory use, sorting proofs minimize computation, and commitment proofs minimize network communication. Using bit-splitting proofs, it takes an IoT client using a CortexM microcontroller 4 minutes of compute time to privately control its share of an energy resource for a day at 20s granularity.

Laufer, Evan↗
DOE OSTI2013

Back from the Brink with Something for Everyone - The Final Executed Memorandum of Agreement for Interpretation of the East Tennessee Technology Park and the K-25 Building - 13370

When the Environmental Management (EM) Program at the Oak Ridge Office of the Department of Energy (DOE) began its major decontamination and decommissioning (D and D) program activities in the mid-1990's, it was understood that the work to demolish the gaseous diffusion process buildings at the K-25 Site, as it was then known, would be challenging. Nothing of that size and breadth had ever been done within the DOE complex and the job brought about a full menu of unique attributes: radiological contamination with enriched materials entrained in certain areas of the system, a facility that was never designed not to operate but had been shut down since 1964, and a loyal following of individuals and organizations who were committed to the physical preservation of at least some portion of the historic Manhattan Project property. DOE was able to solve and resolve the issues related to nuclear materials management, contamination control, and determining the best way to safely and efficiently deconstruct the massive building. However, for a variety of reasons, resolution of the historic preservation questions - what and how much to preserve, how to preserve it, where to preserve it, how to interpret it, how much to spend on preservation, and by and for whom preservation should occur - remained open to debate for over a decade. After a dozen years, countless meetings, phone calls, discussions and other exchanges, and four National Historic Preservation Act (NHPA) [1] Memoranda of Agreement (MOA), a final MOA [2] has been executed. The final executed MOA's measures are robust, creative, substantive, and will be effective. They include a multi-story replica of a portion of the K-25 Building, the dedication of the K-25 Building footprint for preservation purposes, an equipment building to house authentic Manhattan Project and Cold War equipment, a virtual museum, an on-site history center, a grant to preserve a historically-significant Manhattan Project-era hotel in Oak Ridge, and more. The MOA was designed to offer something for everyone. The MOA for the K- 25 Building and interpretation of the East Tennessee Technology Park (ETTP; formerly the K-25 Site) was executed by all of the signatory parties on August 7, 2012 - almost 67 years to-the-day after the 'product' of the K-25 process building became known to more than just a small group of scientists and engineers working on a secret project for the Army Corps of Engineers Manhattan District. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1972

Thermal scale modeling of radiation-conduction-convection systems.

Investigation of thermal scale modeling applied to radiation-conduction-convection systems with particular emphasis on the spacecraft cabin atmosphere/cabin wall thermal interface. The 'modified material preservation,' 'temperature preservation,' 'scaling compromises,' and 'Nusselt number preservation' scale modeling techniques and their inherent limitations and problem areas are described. The compromised scaling techniques of mass flux preservation and heat transfer coefficient preservation show promise of giving adequate thermal similitude while preserving both gas and temperature in the scale model. The use of these compromised scaling techniques was experimentally demonstrated in tests of full scale and 1/4 scale models. Correlation of test results for free and forced convection under various test conditions shows the effectiveness of these scaling techniques. It is concluded that either mass flux or heat transfer coefficient preservation may result in adequate thermal similitude depending on the system to be modeled. Heat transfer coefficient preservation should give good thermal similitude for manned spacecraft scale modeling applications.

Shannon, R. L.↗