Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “task work”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,027 records · Page 57
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

An Application of the SSHAC Level 3 Process to the Probabilistic Seismic Hazard Analysis for Nuclear Facilities at the Hanford Site, Eastern Washington, USA

Under the sponsorship of the US Department of Energy (DOE) and the electric utility Energy Northwest, the Pacific Northwest National Laboratory (PNNL) is conducting a probabilistic seismic hazard analysis (PSHA) within the framework of a SSHAC Level 3 procedure (Senior Seismic Hazard Analysis Committee; Budnitz et al., 1997). Specifically, the project is being conducted following the guidelines and requirements specified in NUREG-2117 (USNRC, 2012b) and consistent with approach given in the American Nuclear Standard ANSI/ANS-2.29-2008 Probabilistic Seismic Hazard Analysis. The collaboration between DOE and Energy Northwest is spawned by the needs of both organizations for an accepted PSHA with high levels of regulatory assurance that can be used for the design and safety evaluation of nuclear facilities. DOE committed to this study after performing a ten-year review of the existing PSHA, as required by DOE Order 420.1C. The study will also be used by Energy Northwest as a basis for fulfilling the NRC’s 10CFR50.54(f) requirement that the western US nuclear power plants conduct PSHAs in conformance with SSHAC Level 3 procedures. The study was planned and is being carried out in conjunction with a project Work Plan, which identifies the purpose of the study, the roles and responsibilities of all participants, tasks and their associated schedules, Quality Assurance (QA) requirements, and project deliverables. New data collection and analysis activities are being conducted as a means of reducing the uncertainties in key inputs to the PSHA. It is anticipated that the results of the study will provide inputs to the site response analyses at multiple nuclear facility sites within the Hanford Site and at the Columbia Generating Station.

Nuclear Facilities↗
DOE OSTI2021

VERIFICATION OF TRISO FUEL BURNUP USING MACHINE LEARNING ALGORITHMS

Pebble Bed Reactors are fueled with fuel pebbles that are circulated multiple times through the reactor vessel before discharge. During the normal operation of a PBR, ejected pebbles are returned to the reactor or discharged depending on the fuel burnup and physical condition of the pebbles. The burnup measurement is usually based on detected radiation signatures of fission products accumulated in the pebble fuel over burnup. Previous research has shown that height of photopeaks of fission products, such as 134Cs, 137Cs, 154Eu, etc., can be used independently or in combination to infer or predict the level of burnup in the fuel. However, it remains challenging to measure such complex sources due to self-shielding effects, strong radiation background and intervening materials. Another operational challenge is the required high throughput of burnup measurement, which necessitates limited measurement time and thus impacts quality of measured gamma-ray spectra. Hence, advanced spectral analysis methods are needed to analyze the noisy gamma spectra and predict the burnup values. We propose to use machine learning (ML) method to interpret gamma-ray spectra and predict the burnup values of the pebbles. ML has achieved widespread success and adoption across a few domains that require pattern recognition and analysis in varied data types. In this work, we apply three proven ML approaches - multilayer perceptrons, convolutional neural networks, and transformers - to the task of predicting fuel burnup from measured gamma spectra, and compile a dataset of simulated spectra for training and validation of the ML models. In this paper, we will discuss the network architecture of these three ML approaches and compare the performance of the simplest of these (MLP) to a standard linear regression.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2012

Getting Beyond Yucca Mountain - 12305

The U.S. Department of Energy has terminated the Yucca Mountain repository project. The U.S. Nuclear Regulatory Commission has indefinitely suspended the Yucca Mountain licensing proceeding. The presidentially-appointed Blue Ribbon Commission (BRC) on America's Nuclear Future is preparing a report, due in January 2012, to the Secretary of Energy on recommendations for a new national nuclear waste management and disposal program. The BRC Draft Report published in July 2011 provides a compelling critique of the past three decades failed efforts in the United States to site storage and disposal facilities for spent nuclear fuel (SNF) and high-level radioactive waste (HLW). However, the BRC Draft Report fails to provide detailed guidance on how to implement an alternative, successful approach to facility site selection. The comments submitted to the BRC by the State of Nevada Agency for Nuclear Projects provide useful details on how the US national nuclear waste program can get beyond the failed Yucca Mountain repository project. A detailed siting process, consisting of legislative elements, procedural elements, and 'rules' for volunteer sites, could meet the objectives of the BRC and the Western Governors Association (WGA), while promoting and protecting the interests of potential host states. The recent termination of the proposed Yucca Mountain repository provides both an opportunity and a need to re-examine the United States' nuclear waste management program. The BRC Draft Report published in July 2011 provides a compelling critique of the past three decades failed efforts in the United States to site storage and disposal facilities for SNF and HLW. It is anticipated that the BRC Final report in January 2012 will recommend a new general course of action, but there will likely continue to be a need for detailed guidance on how to implement an alternative, successful approach to facility site selection. Getting the nation's nuclear waste program back on track requires, among other things, new principles for siting-principles based on partnership between the federal implementing agency and prospective host states. These principles apply to the task of developing an integrated waste management strategy, to interactions between the federal government and prospective host states for consolidated storage and disposal facilities, and to the logistically and politically complicated task of transportation system design. Lessons from the past 25 years, in combination with fundamental parameters of the nuclear waste management task in the US, suggest new principles for partnership outlined in this paper. These principles will work better if well-grounded and firm guidelines are set out beforehand and if the challenge of maintaining competence, transparency and integrity in the new organization is treated as a problem to be addressed rather than a result to be expected. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2012

Improving DOE Project Performance Using the DOD Integrated Master Plan - 12481

DOE O 413 measures a project's progress to plan by the consumption of funding, the passage of time, and the meeting of milestones. In March of 2003, then Under Secretary, Energy, Science, Card received a memo directing the implementation of Project Management and the Project Management Manual, including the Integrated Master Plan and Integrated Master Schedule. This directive states 'the integrated master plan and schedule tie together all project tasks by showing their logical relationships and any constraints controlling the start or finish of each task. This process results in a hierarchy of related functional and layered schedules derived from the Work Breakdown Structure that can be used for monitoring and controlling project progress'. This paper shows how restoring the IMP/IMS paradigm to DOE program management increases the probability of program success in ways not currently available using DOD O 413 processes alone. Using DOE O 413 series guidance, adding the Integrated Master Plan and Integrated Master Schedule paradigm would provide a hierarchical set of performance measures for each 'package of work,' that provides measurable visibility to the increasing maturity of the project. This measurable maturity provides the mechanism to forecast future performance of cost, schedule, and technical outcomes in ways not available using just the activities in DOE O 413. With this information project managers have another tool available to address the issues identified in GAO-07-336 and GAO-09-406. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

Global inventory and meta-analysis of offshore geologic carbon storage efforts

Poster for presentation at the American Geophysical Union Fall Meeting 2023 detailing work conducted for the Carbon Storage Data Field Work Proposal. This poster presents an inventory and meta-analysis conducted for Carbon Storage Data Task 4, which includes a review of offshore geologic carbon storage projects worldwide including site characterization, resource estimates, and transport information.

Mark-Moser, Mackenzie K.↗
DOE OSTI2018

Sensing and Sampling of Trace Contaminations by a Dexterous Hexrotor UAV at Nuclear Facilities - 18600

Safe and efficient cleanups are a priority for decontamination and decommissioning of nuclear facilities. The contaminations of byproducts and wastes in such nuclear facilities pose a serious problems while decommissioning, to both the operators and public. Sensing these contaminations and cleaning them is an essential part of the safety procedures. The contaminations might range from low-energy to high-energy byproducts. Sensing these byproducts would require contact based or non-contact based sensing, based on its energy levels. Byproducts such as americium, are low-energy which makes it difficult to sense and sample without contact. Therefore, the workers need to physically swab the surfaces to collect the samples of these contaminations. These tasks pose a great danger for the safety of the human workers which includes the risk to reach greater heights, exposure to the radiation and sampling the entire building. A robotic solution is much more desirable in these cases, where the worker can safely handle the contaminations from a safe area. Use of robotic technologies inside these hazardous environments ensures the safety and enhances the performance. The more suitable robotic solution for reaching great heights and covering large areas of nuclear facilities, are aerial vehicles. Multi-rotor unmanned aerial vehicle (UAV) are chosen for their ability to hover at a position and also fly around in confined spaces. Quadrotors are a common choice of multi-rotor UAVs both research and industry because of its ease to fly and commercial availability. For the applications during the cleanups we need the UAV to not only hover and fly in confined spaces, but also interact with the physical world. Despite of quadrotor's advantages, they are not a best suit as they can't interact with the physical world. The tasks involving physical interactions would require the UAV to apply arbitrary forces and torques in all six degrees of freedom (DOF). As quadrotors are under-actuated and non-holonomic in motion, they cannot exert all the required forces. At Collaborative Robotics Lab, Purdue University, we developed a novel multi-rotor UAV solution, Dexterous Hexrotor, which can exert arbitrary forces and torques in all six DOF, independently and instantaneously. This enables the UAV platform to quickly respond to the external disturbances and precisely hold its position during the mission. The Dexterous Hexrotor serves as a robotic tool for the workers to perform sensing and sampling during the cleanups. Workers can operate Dexterous Hexrotor manually and/or semi-autonomously with human intervention. Manual control requires the worker to fly the Dexterous Hexrotor using a remote control. So the workers should possess knowledge on flying the UAV and to perform physical interaction. A semiautonomous Dexterous Hexrotor requires human input to some extent and requires very less knowledge of flying. The autonomy is designed to operate in flight mode and sampling mode. In flight mode, Dexterous Hexrotor takes off from a 'safe' area, reaches the desired altitude, and fly autonomously towards a sampling point. This sampling point is the target position specified on the 2D reference map. This mode also includes navigation towards the sampling point, avoiding the obstacles in the constrained environment. After reaching a stopping point, Dexterous Hexrotor waits for the human input for a target location to swab and collect samples. The Dexterous Hexrotor is now in sampling mode and waits for the human input. The human operator selects the swabbing location through the live streaming video from onboard camera. Through visual servoing, aided by the map, the UAV will move closer towards the target position. It then transitions to the impact control scheme to perform physical interaction with the wall and collects samples. Once the sample is collected, it autonomously returns back to the takeoff position in 'safe' area for the analysis by mass spectrometry. In this paper, we majorly focus on the physical interaction strategy and the required components which enables the autonomy. Decommissioning of nuclear facilities requires decontamination inside the entire buildings. Decontamination of nuclear facilities involves sensing and sampling the huge buildings, long shafts, etc. Sampling the entire facility is not possible due to the limitation in Dexterous Hexrotor's flight time. But this can be achieved by using a swarm of Dexterous Hexrotors to cover larger areas. The onboard robotic arm can be designed based on the applications such as cleaning, applying sealants, etc. The modularity of the design allows us to switch components as per the requirements of the task. These kind of robotic solutions functioning as tools for the workers, aims to make the work environment safer and playful. (authors)

42 ENGINEERING↗
DOE OSTI2020

The Evaluation of Chemical Decontamination for Contaminated Carbon Steel Scrap by Multiphase Treatment Process - 20249

There is a significant growth in the field of decommissioning of nuclear facilities due the fact that for a lot of them their end of life is nearing. In Taiwan, the government plans to steadily reduce the dependence on nuclear power and moves gradually towards a nuclear-free homeland. Therefore, the development of decommissioning technology becomes the significant issue for the next coming years. The decommissioning of a nuclear power plant is a long process and practical work including radiological surveys, decontamination, dismantling, and the subsequent waste management. Chemical decontamination is an important task in the decommissioning of nuclear power plants and is usually performed by circulating the chemical solution in selected systems or full systems in order to reduce dose levels. However, the decontamination of segmented metal parts is also considered to reduce the contamination to such levels that they may be disposed of at a lower classification or be unconditionally released, and it helps to achieve the goal of waste minimization and provide a more economical cost for disposal management. Chemical decontamination technology is used to remove the contaminated oxides deposited on the surface of metals by dissolving them with chemical mechanisms, such as chelation, acidic or alkaline dissolution, redox reaction and so on. Carbon steel is the major material used in systems and pipelines in the nuclear power plant, thus it is also commonly selected as the target to be decontaminated in the decommissioning process. In this study, the effectiveness of chemical decontamination is evaluated by using multiphase treatment process including the reduction and the oxidation steps. In the step of redox reaction, the oxidation state of the substance is very important. Especially metals of some oxidation states show solubility in water, which has a decisive influence on the chemical decontamination. The experiment of decontamination of metal scraps is carried out by the immersion method within a chemical solution. The relative operation parameters such as temperature, pH, and concentration of the chemical solution are recorded to demonstrate the effect of the decontamination process. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Assessment on Transport of Radioactive Species from Nuclear Facilities - 17079

It is generally recognized that radioactive nuclides are most hazardous fission products that could be released in the event of reactor accidents. The reactor coolant system of a pressurized water reactor (PWR) nuclear plant exhibits radioactivity from various sources. These radiation sources consist of the fission products from fuel element and activated products from corrosion products. The complex infrastructure of the processes does not allow detailed measurement of activity until after the reactor is shutdown. All of the components that require dismantling will be radioactive which was caused by neutron activation during operation, contamination by corrosion products, contamination by damaged by fuel rods and leaks by equipment. Due mainly to the various operation modes and their aging, there are the increasing needs to carry out repair works that are not sufficiently provided for by the original design. Many difficulties are involved in these tasks, namely, high radiation doses, cramped areas, hard to reach components, coupled with stringent quality conditions. The need to simulate the behavior of corrosion products in a nuclear power plant environment has attracted many researchers' attention. It has performed the in-depth reviews of the various theories and physics associated with the corrosion products transportation, the laboratory loop testing, and the field measurements in operating plants. Before we start the decommissioning of nuclear power plants, workers, the public and the environment shall be properly protected from radiation hazards. For this purpose, a safety assessment should be carried out relating to the potential hazards that may occur during the decommissioning. The radiological hazards involved in the decommissioning activities also should be identified, and be taken into account in the safety assessment. The radiation conditions of the primary circuit are determined by the activity of corrosion and fission products that have accumulated on the internal surfaces of the components. Therefore the estimation of contamination on the components is very important and, may be the first step in the reactor operation and decommissioning of components. The predominant radionuclide in the PWR primary coolant is Co-60, although Co-58 contributes significantly to radioactivity level at the early stage of a reactor operation. Since Co-60 is produced from the in-core Co-58, which is the source of cobalt in a reactor coolant system, many researchers have investigated its transmutation in the core, its transport around the system, and its subsequent deposition on surfaces. The major parameter influencing the behavior of radioactivity, such as Co-60 in the coolant, is the corrosion product oxides. The objective of this work is to analyze the corrosion product activity transported in the primary circuit by using a multi-region model. This model, which is incorporated with the mass and activity transport between the dissolved corrosion products in the coolant and the surface, describes the specific activity of corrosion products in coolant and on the surfaces according to the operation modes as well as decommissioning stage. In order to evaluate the analysis of the corrosion products in an integral type reactor, a multi-region mass balance model is applied. The specific activities of the various species on the surface of core and steam generator throughout the effective full power hours, 15,000 hours, are simulated for the various modes of operations. As a result, the specific activities of corrosion products from the surface of primary circuit were shown as very low compared to those of other commercial nuclear power plants. In this simulated reactor, a significant reduction of specific activities from the activated corrosion products is obtained due to the introduction of titanium alloy to the steam generator tube and the avoidance of boric acid induced corrosion. From this result we conclude that we are able to predict the level of radioactive nuclides generated by corrosion products in a primary circuit according to the various modes of operations by using multi-region model. In this point of view it is concluded that this multi-region model can be used as an engineering tool for analysis of the corrosion products within the primary coolant for the nuclear power plants. It is also considered that it is possible to extend to a calculation tool for estimating the radiological hazards involved in the decommissioning activities in terms of safety assessment. (authors)

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2017

Towards Cooperative Control of Humanoid Robots for Handling High-Consequence Materials in Gloveboxes - 17291

In this paper, we describe our ongoing work with NASA's Valkyrie humanoid robot and present preliminary results on cooperative control of Valkyrie's hands for performing dexterous manipulation tasks inside gloveboxes commonly found in many nuclear facilities. First, we discuss our human-supervised robot control framework which is based on optimization-based whole-body motion and manipulation controllers. A key aspect of this approach is perception based grasping. We develop a grasping control module for realizing the grasps corresponding to sample tasks such as power, ball, key, pinch, and open palm grasps and their variations. Next, we introduce the notion of motion template library in order to develop generalizable robot grasping and manipulation. Motion template library stores the constraint setting information for the constrained motion planning methods and a framework which can implement the motion template library on different types of robots for accomplishing similar tasks. Motion templates are defined only based on the task requirements. As a result, they can be easily ported to different robot platforms. Lastly, we discuss our multi-modal interfaces designs which include a visual display for improved situational awareness as well as a tactile glove for robot hand control and feedback. Our goal is for the person tele-operating the Valkyrie robot to have better sensing and control than what he or she would have if actually standing at the glovebox doing the work. This improved sensing is comprised of the ability to 'see through' the robot's arms and hands in the gloves and to have an improved sense of touch. The paper concludes with a discussion of our validation strategy. Our success metrics are derived from the completion of a relatively complex experiment to be performed in the glovebox. We evaluate various realistic experiments and use them for task validation and demonstration with Valkyrie. We use speed, time of completion, accuracy, repeatability and reliability rates as success metrics by designing replicable experiments. (authors)

42 ENGINEERING↗
DOE OSTI2019

Ultra Efficient Light Duty Powertrain with Gasoline Low Temperature Combustion (Final Report)

This document details the work completed during Project DE-EE0006839 ‘Ultra Efficient Light Duty Powertrain with Gasoline Low Temperature Combustion’. All tasks from the project’s Statement of Project Objectives are discussed. Final demonstration data is also presented and discussed. Further project details can be found in the Quarterly Technicial Reports that were submitted during the course of the project and are stored on the EERE Project Management Center Website. The goal of this project was to develop, implement and demonstrate a low temperature combustion approach called Gasoline Direct Injection Compression Ignition (GDCI) that provides high thermal efficiency with low NOx and PM emissions. The project target was to demonstrate a 35% fuel economy improvement over the baseline vehicle while meeting Tier 3 emissions levels. At the start of this project, GDCI was a moderately mature combustion technology, due in large part to advances made during a Delphi Technologies program funded through an earlier Department of Energy Advanced Technology Powertrains (ATP) opportunity; under that earlier contract, DE-EE0003258, Delphi Technologies assembled a team with complementary industrial and academic experience, and led this team to advance the technology from the original fundamental work to the state of art embodied by a first-generation (Gen 1) multi-cylinder GDCI engine. Key activities during that project centered on engine and combustion chamber design, and development of fuel injection equipment, valvetrain and advanced controls. Performance results with the Gen 1 engine in a development vehicle demonstrated that GDCI had the capability to operate using Low Temperature Combustion (LTC) over a broad speed-load range. Based on benchmarking work, efficiency for the Gen 1 GDCI engine compared favorably overall to production light-duty diesel engines. The second DOE funded project, DE-EE0006839, focused on a number of technical risks and issues that were left to be resolved for GDCI to become a production-viable technology. These risks were:GDCI combustion system refinement to achieve near-ideal air/fuel mixture preparation for high efficiency and low HC and CO emissions; Transient control development for low temperature combustion with high EGR levels during real-world transient driving maneuvers and over a broader range of ambient conditions; Aftertreatment system design that is effective in dealing with the low-temperature challenges of a highly efficient engine. The project was executed in two phases. Phase 1 leveraged the development vehicle from the Advanced Technologies Powertrain 1 (ATP1) project, DE-EE0003258. That vehicle was used as an initial test bed in the development of a high performance low temperature exhaust aftertreatment system. The vehicle was also used to develop calibration refinements for improved exhaust emissions and fuel efficiency. Samples of a new GDCI development level engine, called Gen2 GDCI (and developed outside of the first DOE funded project), were also used during Phase 1 to develop refined controller hardware and control algorithms, as well as improved sensors and actuators. The Gen2 engine was then retrofitted into the development vehicle from the ATP1 project and used for controls refinement and calibration of GDCI to achieve improved cold start, drivability and robustness to real world environments and fuel variations. During Phase 2 of the project, Gen3 versions of the GDCI engine were designed and built specifically for this project based on experience from the earlier engines. These engines were designed to be production-like in construction and, when combined with refined control systems and project specific low temperature exhaust aftertreatment, were intended to support the goal of meeting Tier 3 emissions levels at a vehicle level. Though great progress had been made advancing the GDCI combustion process, and despite extensive presentations of our work on the technology at various conferences and in direct meetings with automotive companies, none of the US domestic automotive OEMs had shown an interest in adopting this combustion process as part of their technology planning as the project approached the Go/No-Go point at the end of Budget Period 3. As a result of this low-level of interest both the US Department of Energy and Delphi Technologies received in this technology from domestic auto manufactures, Delphi Technologies elected a ‘No-Go’ status for the gate between Budget Period 3 and Budget Period 4 which terminated the project without spending any Budget Period 4 funds. The project team concluded that the dynamometer mapping of the most recent level of hardware, combined with the vehicle level simulation by Argonne National Laboratory, was sufficient to document the capabilities and potential of the combustion process without spending the time and money to do the controls development and full calibration necessary for a demonstration vehicle.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2024

Development and Assessment of Deployed Sensors and Technologies Supporting Molten Salt Loop Operations

During FY24, Argonne conducted a variety of activities to develop and assess new monitoring and control technologies towards enabling long-duration operations of molten salt reactor systems. The first objective of the work completed this year was to deploy technologies capable of reliably and rapidly monitoring the operational health of a molten salt loop. To achieve this, the project focused on specific tasks, including: (1) electroanalytical technique development for use in deployed sensors, and (2) operations of sensors on the Facility to Alleviate Salt Technology Risks (FASTR) loop at Oak Ridge National Laboratory. The second objective of the work this year focused on creating a pumped actinide flow loop to enable long-duration salt chemistry and corrosion studies using uranium-bearing fuel salts. Toward that end, we designed and procured a loop capable of being installed into a radiological glovebox at Argonne. A corrosion control system was also designed for integration into this loop. These combined systems will enable the feasibility of corrosion control and management systems to be investigated with complex chloride fuel salt mixtures.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2020

Automated Design of Neuromorphic Networks for Scientific Applications at the Edge

Designing spiking neural networks for neuromorphic deployment is a non-trivial task. It is further complicated when there are resource constraints for the neuromorphic implementation, such as size or power constraints, that may be present in edge applications. In this work, we utilize a previously presented approach, EONS, to design spiking neural networks for a memristive neuromorphic implementation for scientific data applications. We specifically use a multi-objective approach in EONS to maximize network accuracy on the scientific data application task, but also to minimize network size and energy. We illustrate that EONS determines both the network structure and the parameters, removing the burden from the user on determining the appropriate spiking neural network structure, and we show that the resulting networks are very different from the layered structure of typical neural networks. Finally, we show that the multi-objective approach produces smaller, more energy efficient networks than the original EONS approach and produces comparable accuracy to a back-propagation style training approach.

Schuman, Catherine↗
DOE OSTI2017

Pseudo-Spectral Methods for the Laplace-Beltrami Equation and the Hodge Decomposition on Surfaces of Genus One

The inversion of the Laplace-Beltrami operator and the computation of the Hodge decomposition of a tangential vector field on smooth surfaces arise as computational tasks in many areas of science, from computer graphics to machine learning to computational physics. In this work, we present a high-order accurate pseudo-spectral approach, applicable to closed surfaces of genus one in three-dimensional space, with a view toward applications in plasma physics and fluid dynamics.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

Entanglement estimation in non-optimal qubit states

Highlights: • Quantum Fisher Information. • Entanglement Estimation. • Squeezed States. • Husimi Function. - Abstract: In the last years, a relationship has been established between the quantum Fisher information (QFI) and quantum entanglement. In the case of two-qubit systems, all pure entangled states can be made useful for sub-shot-noise interferometry while their QFI meets a necessary and sufficient condition (Hyllus et al., 2010). In M-qubit systems, the QFI provides just a sufficient condition in the task of detecting the degree of entanglement of a generic state (Pezzé and Smerzi, 2009). In our work, we show analytically that, for a large class of one-parameter non-optimal two-qubit states, the maximally entangled states are associated with stationary points of the QFI, as a function of such parameter. We show, via numerical simulations, that this scenario is maintained for the generalisation of this class of states to a generic M-qubit system. Furthermore, we suggest a scheme for an interferometer able to detect the entanglement in a large class of two-spin states.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Energy-saving opportunities of direct-DC loads in buildings

Despite the recent interest in direct current (DC) power distribution in buildings, the market for DC-ready loads remains small. The existing DC loads in various products or research test beds are not always designed to efficiently leverage the benefits of DC. This work addresses a pressing need for a study into the development of efficient DC loads. In particular, it focuses on documenting and demonstrating how to best leverage a DC input to eliminate or improve conversion stages in a load's power converter. This work identifies how typical building loads can benefit from DC input, including bath fans, refrigerators, wall adapters, task lights, and zone lighting. It then details the development of several prototypes that demonstrate efficiency savings with DC. The most efficient direct-DC loads are explicitly designed for DC from the ground up, rather than from an AC modification.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2019

EDRIXS: An open source toolkit for simulating spectra of resonant inelastic x-ray scattering

Resonant inelastic x-ray scattering (RIXS) has become a very powerful experimental technique to probe a broad range of intrinsic elementary excitations, for example, from low energy phonons and (bi-)magnons to high energy d-d, charge-transfer and plasmon excitations in strongly correlated electronic systems. Due to the complexity of the RIXS cross-section and strong core-hole effects, theoretical simulation of the experimental RIXS spectra is still a difficult task which hampers the understanding of RIXS spectra and the development of the RIXS technique. In this work, we present an open source toolkit (dubbed EDRIXS) to facilitate the simulations of RIXS spectra of strongly correlated materials based on exact diagonalization (ED) of certain model Hamiltonians. The model Hamiltonian can be from a single atom, small cluster or Anderson impurity model, with model parameters from density functional theory plus Wannier90 or dynamical mean-field theory calculations. The spectra of x-ray absorption spectroscopy (XAS) and RIXS are then calculated using Krylov subspace techniques. This toolkit contains highly efficient ED, XAS and RIXS solvers written in modern Fortran 90 language and a convenient Python library used to prepare inputs and set up calculations. We first give a short introduction to RIXS spectroscopy, and then we discuss the implementation details of this toolkit. Lastly, we show three examples to demonstrate its usage.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Physics-informed neural networks: A deep learning framework for solving forward and inverse problems involving nonlinear partial differential equations

Hejre, we introduce physics-informed neural networks – neural networks that are trained to solve supervised learning tasks while respecting any given laws of physics described by general nonlinear partial differential equations. In this work, we present our developments in the context of solving two main classes of problems: data-driven solution and data-driven discovery of partial differential equations. Depending on the nature and arrangement of the available data, we devise two distinct types of algorithms, namely continuous time and discrete time models. The first type of models forms a new family of data-efficient spatio-temporal function approximators, while the latter type allows the use of arbitrarily accurate implicit Runge–Kutta time stepping schemes with unlimited number of stages. Moreover, the effectiveness of the proposed framework is demonstrated through a collection of classical problems in fluids, quantum mechanics, reaction–diffusion systems, and the propagation of nonlinear shallow-water waves.

97 MATHEMATICS AND COMPUTING↗