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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 955 records · Page 53
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Helping IT and OT Defenders Collaborate

Cyber-physical systems, especially in critical infrastructures, have become primary hacking targets in international conflicts and diplomacy. However, cyber-physical systems present unique challenges to defenders, starting with an inability to communicate. This paper outlines the results of our interviews with information technology (IT) defenders and operational technology (OT) operators and seeks to address lessons learned from them in the structure of our notional solutions. We pre-sent two problems in this paper: (1) the difficulty of coordinat-ing detection and response between defenders who work on the cyber/IT and physical/OT sides of cyber-physical infrastruc-tures, and (2) the difficulty of estimating the safety state of a cyber-physical system while an intrusion is underway but be-fore damage can be effected by the attacker. To meet these chal-lenges, we propose two solutions: (1) a visualization that will enable communication between IT defenders and OT operators, and (2) a machine-learning approach that will estimate the distance from normal the physical system is operating and send information to the visualization.

Cyber Physical Systems, internet of things, visual↗
DOE OSTI2018

Setting the Smart Solar Standard: Collaborations Between Hawaiian Electric and the National Renewable Energy Laboratory

Driving through many neighborhoods of Hawai'i, it is hard to miss the nearly ubiquitous rooftop solar photovoltaic (PV) systems that have popped up during the past eight years or so. Relatively high electricity costs associated with island grids, coupled with various incentives, have made it cost-effective to install solar over the last eight years, as evidenced by the PV-deployment chart in Figure 1. On the most populous island, O'ahu, the PV nameplate acgenerating capacity of 502 MW totals nearly half of the annual peak load for the entire island, which is 1.1 GW . Of that 502 MW of PVs, 54% is from private rooftop solar-nearly 50,000 residences or roughly one of every three single family homes. But Hawaiian Electric, the local utility, has no way to monitor or control the PV generation, even for most nonresidential systems. This means that on sunny days, up to approximately half of the PV generation is outside of the utility's control. This poses many challenges for utility planners and operators-challenges that Hawaiian Electric has been working diligently to address, along with various partners, notably the U.S. Department of Energy (DOE), the National Renewable Energy Laboratory (NREL), and its Energy System's Integration Facility (ESIF). This article describes how Hawaiian Electric has worked with engineers in NREL's Power Systems Engineering Center to improve the way its grid operates with very high levels of distributed PVs, largely by changing the way the PV inverters are operated.

14 SOLAR ENERGY↗
DOE OSTI2025

Physics-Informed Graph Neural Networks for Collaborative Dynamic Reconfiguration and Voltage Regulation in Unbalanced Distribution Systems

Network reconfiguration has long been employed as a strategic approach to minimize power distribution system losses and effectively regulate voltage levels. Tap-changing voltage regulators are also critical for controlling bus voltages, especially in accommodating the increasing integration of distributed energy resources (DERs) with intermittent outputs. This paper introduces novel methodologies to address the challenges of dynamic reconfiguration and optimal tap setting in unbalanced three-phase distribution systems. We propose an approximated mixed-integer quadratically constrained program (MIQCP) to model dynamic reconfiguration, along with a pioneering formulation for voltage regulator (VR) tap-setting based on Special Ordered Set type 1 (SOS1). To mitigate computational complexity, we propose a physics-informed spatial-temporal graph convolutional network (STGCN) with an integrated link classifier. The proposed approach enables efficient solution generation by fixing specific variables in the MIQCP instance and solving the simplified sub-MIP using an MIP solver. Numerical studies demonstrate the superior prediction accuracy of our STGCN model compared to baseline neural network models, resulting in reduced DER curtailment and voltage deviation with shorter computation time.

dynamic reconfiguration↗
DOE OSTI2020

Improving collaborations between empiricists and modelers to advance grassland community dynamics in ecosystem models

Climate change, increasing atmospheric CO 2 , and land use change have altered biogeochemical and hydrologic cycles world-wide, with grassland systems being particularly vulnerable to resulting vegetation shifts (Komatsu et al., 2019). Therefore, incorporating plant community dynamics into ecosystem models is critical for accurate forecasting of ecosystem responses to global change (Levine, 2016). Process-based ecosystem models, which simulate the biogeochemical transfers of mass and energy among biota, the subsurface, and atmosphere, require representation of dynamic composition of organisms within ecosystems. For example, these models simulate leaf and plant-level characteristics, such as electron transport rate and allometry of carbon (C) allocation, to predict how net primary productivity and other ecosystem processes respond to abiotic drivers. These models are particularly useful in scaling from organismal to ecosystem levels but are still underdeveloped in their ability to capture community change, especially in grassland ecosystems. To represent compositional changes, these models must simulate competition, mortality, establishment, and reproduction of plant populations within communities. Yet, current ecosystem modeling approaches to forecast plant community change have derived from studies of forested systems and are either too coarse to capture fine-scale community dynamics (e.g. dynamic global vegetation models (DGVMs)) or too complex to be used at large spatial scales (e.g. forest gap models).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2014

Poster — Thur Eve — 52: A Web-based Platform for Collaborative Document Management in Radiotherapy

We describe DepDocs, a web-based platform that we have developed to manage the committee meetings, policies, procedures and other documents within our otherwise paperless radiotherapy clinic. DepDocs is essentially a document management system based on the popular Drupal content management software. For security and confidentiality, it is hosted on a linux server internal to our hospital network such that documents are never sent to the cloud or outside of the hospital firewall. We used Drupal's in-built role-based user rights management system to assign a role, and associated document editing rights, to each user. Documents are accessed for viewing using either a simple Google-like search or by generating a list of related documents from a taxonomy of categorization terms. Our system provides document revision tracking and an document review and approval mechanism for all official policies and procedures. Committee meeting schedules, agendas and minutes are maintained by committee chairs and are restricted to committee members. DepDocs has been operational within our department for over six months and has already 45 unique users and an archive of over 1000 documents, mostly policies and procedures. Documents are easily retrievable from the system using any web browser within our hospital's network.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2015

SU-C-BRD-01: Multi-Centre Collaborative Quality Assurance Program for IMRT Planning and Delivery: Year 3 Results

Purpose: A multi-centre quality assurance program was developed to enable quality improvement by coupling measurement of intensity modulated radiotherapy (IMRT) planning and delivery performance for site-specific planning exercises with diagnostic testing. The third year of the program specifically assessed the quality of spine stereotactic body radiotherapy (SBRT) planning and delivery amongst the participating centres. Methods: A spine SBRT planning exercise (24 Gy in 2 fractions) was created and completed by participants prior to an on-site visit. The delivery portion of the on-site visit included spine SBRT plan delivery and diagnostic testing, which included portal image acquisition for quantification of phantom positioning error and multi-leaf collimator (MLC) calibration accuracy. The measured dose was compared to that calculated in the treatment planning system (TPS) using 3%/2mm composite analysis and 3%/3mm gamma analysis. Results: Fourteen institutions participated, creating 17 spine SBRT plans (15 VMAT and 2 IMRT). Three different TPS, two beam energies (6 MV and 6 MV FFF), and four MLC designs from two linac vendors were tested. Large variation in total monitor units (MU) per plan (2494–6462 MU) and dose-volume parameters was observed. The maximum point dose in the plans ranged from 116–149% and was dependent upon the TPS used. Pass rates for measured to planned dose comparison ranged from 89.4–100% and 97.3–100% for 3%/2mm and 3%/3mm criteria respectively. The largest measured MLC error did Result in one of the poorer pass rates. No direct correlation between phantom positioning error and pass rates overall. Conclusion: Significant differences were observed in the planning exercise for some plan and dose-volume parameters based on the TPS used. Standard evaluation criteria showed good agreement between planned and measured dose for all participants, however on an individual plan basis, diagnostic tests were able to identify contributing factors for poorer results, when using more stringent evaluation criteria. Funding from Cancer Care Ontario is acknowledged.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Results from the CMS collaboration on the search of heavy dilepton and diphoton resonances

A survey of the results on the search of new heavy resonances decaying into muon, electron, or photon pairs in the CMS experiment at proton beams of the LHC in the run of 2015 for the total center of mass energy √ s = 13 TeV is presented. The limits for heavy resonance production cross sections are set. Excess of diphoton events in the region of mass spectra near 750 GeV with a local statistical significance of 3.4 σ and a global statistical significance of 1.6 σ is observed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗