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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 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

NREL Develops New Controls that Proactively Adapt to the Wind [Fact Sheet]

Until now, wind turbine controls that reduce the impacts of wind gusts and turbulence were always reactive—responding to the wind rather than anticipating it. But with today's laser-based sensors that measure wind speed ahead of the turbine, researchers at the National Renewable Energy Laboratory (NREL) and their industry partners are developing more intelligent controls. The world's first field tests of these controls are currently underway at the National Wind Technology Center (NWTC) at NREL, with plans for future commercialization.

17 WIND ENERGY↗
DOE OSTI2012

NREL Uses Computing Power to Investigate Tidal Power (Fact Sheet)

Until now, wind turbine controls that reduce the impacts of wind gusts and turbulence were always reactive - responding to the wind rather than anticipating it. But with today's laser-based sensors that measure wind speed ahead of the turbine, researchers at the National Renewable Energy Laboratory (NREL) and their industry partners are developing more intelligent controls. The world's firstfield tests of these controls are currently underway at the National Wind Technology Center (NWTC) at NREL, with plans for future commercialization.

16 TIDAL AND WAVE POWER↗
DOE OSTI2021

Optical vortex manipulation for topological quantum computation

Topological quantum computation based on Majorana bound states may enable new paths to fault-tolerant quantum computing. Several recent experiments have suggested that the vortex cores of topological superconductors, such as iron-based superconductors, may host Majorana bound states at zero energy. However, quantum computation with these zero-energy vortex bound states requires precise and fast manipulation of individual vortices, which is difficult to do in a scalable manner. To address this issue, in this study we propose a control scheme based on local heating via, for example, scanning optical microscopy to braid vortex-bound Majorana zero modes in a two-dimensional topological superconductor. First, we derive the conditions required for transporting a single vortex between two defects in the superconducting material by trapping it with a hot spot generated by local optical heating. Equipped with critical conditions for the vortex motion, we then establish the ideal material properties for vortex braiding and describe how transition errors resulting from finite speed and/or temperature can be minimized. Our work paves the way toward optical or microscopic control of zero-energy vortex bound states in two-dimensional topological superconductors.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Selective and Scalable Control of Spin Quantum Memories in a Photonic Circuit

A central goal in many quantum information processing applications is a network of quantum memories that can be entangled with each other while being individually controlled and measured with high fidelity. This goal has motivated the development of programmable photonic integrated circuits (PICs) with integrated spin quantum memories using diamond color center spin-photon interfaces. However, this approach introduces a challenge into the microwave control of individual spins within closely packed registers. Here, we present a quantum memory-integrated photonics platform capable of (i) the integration of multiple diamond color center spins into a cryogenically compatible, high-speed programmable PIC platform, (ii) selective manipulation of individual spin qubits addressed via tunable magnetic field gradients, and (iii) simultaneous control of qubits using numerically optimized microwave pulse shaping. The combination of localized optical control, enabled by the PIC platform, together with selective spin manipulation opens the path to scalable quantum networks on intrachip and interchip platforms.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Dynamic control of laser driven proton beams by exploiting self-generated, ultrashort electromagnetic pulses

As part of the ultrafast charge dynamics initiated by high intensity laser irradiations of solid targets, high amplitude EM pulses propagate away from the interaction point and are transported along any stalks and wires attached to the target. The propagation of these high amplitude pulses along a thin wire connected to a laser irradiated target was diagnosed via the proton radiography technique, measuring a pulse duration of ∼20 ps and a pulse velocity close to the speed of light. The strong electric field associated with the EM pulse can be exploited for controlling dynamically the proton beams produced from a laser-driven source. Chromatic divergence control of broadband laser driven protons (upto 75% reduction in divergence of >5 MeV protons) was obtained by winding the supporting wire around the proton beam axis to create a helical coil structure. In addition to providing focussing and energy selection, the technique has the potential to post-accelerate the transiting protons by the longitudinal component of the curved electric field lines produced by the helical coil lens.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Modelling and control coordination scheme of a wind‐to‐hydrogen set for future renewable‐based power systems

New challenges regarding system stability and efficiency arise when power systems operate with a high penetration level of inverter‐based renewable sources (IBRSs) and few synchronous generators. Since IBRSs have been on the rise, to secure the stable operation of future power systems, IBRSs will be required to support systems without having to rely on remaining synchronous generators. Also, to efficiently manage the uncertainty of renewable production, power‐to‐gas technology can provide the required flexibility. This study proposes modelling and a control coordination scheme (CCS) of a wind‐to‐hydrogen (W2H) set to optimise electricity production from a variable‐speed wind turbine generator (WTG) while helping balance between supply and demand in a system. To achieve this, a grid‐forming (GFM) inverter‐based WTG is modelled and a set of electrolyser and fuel cell is integrated at the DC circuit of a GFM‐WTG to be coordinated. Furthermore, the CCS offers an opportunity to reduce the investment cost for deploying a W2H set by utilising the control capabilities of a WTG and reducing the need for an additional device. The performance of the proposed W2H set with the CCS was verified considering the variations in system load and wind speed by using Power System Computer Aided Design (PSCAD)/ElectroMagnetic Transients including Direct Current (EMTDC).

Kim, Jinho↗
DOE OSTI2012

NREL Develops New Controls that Proactively Adapt to the Wind (Fact Sheet)

Until now, wind turbine controls that reduce the impacts of wind gusts and turbulence were always reactive-responding to the wind rather than anticipating it. But with today's laser-based sensors that measure wind speed ahead of the turbine, researchers at the National Renewable Energy Laboratory (NREL) and their industry partners are developing more intelligent controls. The world's first field tests of these controls are currently underway at the National Wind Technology Center (NWTC) at NREL, with plans for future commercialization.

17 WIND ENERGY↗
DOE OSTI2023

Deep generative models for vehicle speed trajectories

Generating realistic vehicle speed trajectories is a crucial component in evaluating vehicle fuel economy and in predictive control of self-driving cars. Traditional generative models rely on Markov chain methods and can produce accurate synthetic trajectories but are subject to the curse of dimensionality. They do not allow to include conditional input variables into the generation process. In this paper, we show how extensions to deep generative models allow accurate and scalable generation. Proposed architectures involve recurrent and feed-forward layers and are trained using adversarial techniques. Our models are shown to perform well on generating vehicle trajectories using a model trained on GPS data from Chicago metropolitan area.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2017

Evaluation of the Inertial Response of Variable-Speed Wind Turbines Using Advanced Simulation: Preprint

In this paper, we focus on the temporary frequency support effect provided by wind turbine generators (WTGs) through the inertial response. With the implemented inertial control methods, the WTG is capable of increasing its active power output by releasing parts of the stored kinetic energy when the frequency excursion occurs. The active power can be boosted temporarily above the maximum power points, but the rotor speed deceleration follows and an active power output deficiency occurs during the restoration of rotor kinetic energy. In this paper, we evaluate and compare the inertial response induced by two distinct inertial control methods using advanced simulation. In the first stage, the proposed inertial control methods are analyzed in offline simulation. Using an advanced wind turbine simulation program, FAST with TurbSim, the response of the researched wind turbine is comprehensively evaluated under turbulent wind conditions, and the impact on the turbine mechanical components are assessed. In the second stage, the inertial control is deployed on a real 600-kW wind turbine, the three-bladed Controls Advanced Research Turbine, which further verifies the inertial control through a hardware-in-the-loop simulation. Various inertial control methods can be effectively evaluated based on the proposed two-stage simulation platform, which combines the offline simulation and real-time hardware-in-the-loop simulation. The simulation results also provide insights in designing inertial control for WTGs.

17 WIND ENERGY↗
DOE OSTI2018

Mechanical Properties and Wear Behavior of AA5182/WC Nanocomposite Fabricated by Friction Stir Welding at Different Tool Traverse Speeds

Grain growth inhibition at the heat-affected zone, improved weld strength and superior tribological properties of welds are desirable attributes of modern manufacturing. With the focused on these attributes, tungsten carbide (WC) nanoparticles were employed as reinforcements for the friction stir welding of 5-mm-thick AA5182 aluminum alloy by varying tool traverse speeds. The microstructure, microhardness, ultimate tensile strength, fracture and wear behavior of the resultant WC-reinforced welds were investigated, while unreinforced AA5182 welds were employed as controls for the study. The result shows that the addition of WC nanoparticles causes substantial grain refinement within the weld nugget. A decrease in traverse speed caused additional particle fragmentation, improved hardness value and enhanced weld strength in the reinforced welds. Improved wear rate and friction coefficient of welds were attained at a reduced traverse speed of 100 mm/min in the WC-reinforced welds. This improvement is attributed to the effects of reduced grain size/grain fragmentation and homogeneous dispersion of WC nanoparticles within the WC-reinforced weld nugget.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Perturbed Physics Ensemble Simulations of Cirrus on the Cloud System-resolving Scale

In this study, the effect of uncertainties in the parameterization of ice microphysical processes and initial conditions on the variability of cirrus microphysical and radiative properties are investigated in a series of cloud system-resolving perturbed physics ensemble (PPE) and initial condition ensemble (ICE) simulations. Three cirrus cases representative of mid-latitude, subtropical and tropical cirrus are examined. It is found that the variability in cirrus properties induced by perturbing uncertain parameters in ice microphysics parameterizations outweighs the variability induced by perturbing the initial conditions in midlatitude and subtropical cirrus. However, in tropical anvil cirrus the variability in the PPE and ICE simulations is about the same order of magnitude. The cirrus properties showing the largest sensitivity are ice water content (IWC) and cloud thickness whereas the averaged high cloud cover is only marginally affected. Changes in cirrus ice water path and outgoing longwave radiation are controlled primarily by changes in IWC and cloud thickness but not by changes is the averaged high cloud cover. The change in the vertical distribution of cloud fraction and cloud thickness is caused by changes in cirrus cloud base whereas cloud top is not sensitive to either perturbed physics or perturbed initial conditions. In all cirrus cases, the top three parameters controlling the microphysical variability and radiative impact of cirrus clouds are ice fall speeds, ice autoconversion size thresholds and heterogeneous ice nucleation. Changes in the ice deposition coefficient do not affect the ice water path and outgoing longwave radiation. Similarly, changes in the number concentration of aerosols available for homogeneous freezing have virtually no effect on the microphysical and radiative properties of midlatitude and subtropical cirrus but only little impact on tropical anvil cirrus. Overall, the sensitivity of cirrus microphysical and radiative properties to uncertainties in ice microphysics is largest for midlatitude cirrus and smallest for tropical anvil cirrus.

cirrus↗
DOE OSTI2023

Self‐Propelling Macroscale Sheets Powered by Enzyme Pumps

Abstract Nanoscale enzymes anchored to surfaces act as chemical pumps by converting chemical energy released from enzymatic reactions into spontaneous fluid flow that propels entrained nano‐ and microparticles. Enzymatic pumps are biocompatible, highly selective, and display unique substrate specificity. Utilizing these pumps to trigger self‐propelled motion on the macroscale has, however, constituted a significant challenge and thus prevented their adaptation in macroscopic fluidic devices and soft robotics. Using experiments and simulations, we herein show that enzymatic pumps can drive centimeter‐scale polymer sheets along directed linear paths and rotational trajectories. In these studies, the sheets are confined to the air/water interface. With the addition of appropriate substrate, the asymmetric enzymatic coating on the sheets induces chemically driven, buoyancy flows that controllably propel the sheet's motion on the air/water interface. The directionality and speed of the motion can be tailored by changing the pattern of the enzymatic coating, type of enzyme, and nature and concentration of the substrate. This work highlights the utility of biocompatible enzymes for generating motion in macroscale fluidic devices and robotics and indicates their potential utility for in vivo applications.

Song, Jiaqi↗
DOE OSTI2023

Self‐Propelling Macroscale Sheets Powered by Enzyme Pumps

Nanoscale enzymes anchored to surfaces act as chemical pumps by converting chemical energy released from enzymatic reactions into spontaneous fluid flow that propels entrained nano‐ and microparticles. Enzymatic pumps are biocompatible, highly selective, and display unique substrate specificity. Utilizing these pumps to trigger self‐propelled motion on the macroscale has, however, constituted a significant challenge and thus prevented their adaptation in macroscopic fluidic devices and soft robotics. Using experiments and simulations, we herein show that enzymatic pumps can drive centimeter‐scale polymer sheets along directed linear paths and rotational trajectories. In these studies, the sheets are confined to the air/water interface. With the addition of appropriate substrate, the asymmetric enzymatic coating on the sheets induces chemically driven, buoyancy flows that controllably propel the sheet's motion on the air/water interface. The directionality and speed of the motion can be tailored by changing the pattern of the enzymatic coating, type of enzyme, and nature and concentration of the substrate. This work highlights the utility of biocompatible enzymes for generating motion in macroscale fluidic devices and robotics and indicates their potential utility for in vivo applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Narrowing transient testing pulse widths to enhance LWR RIA experiment design in the TREAT facility

The Transient Reactor Test (TREAT) Facility provided thousands of transient irradiations and plays a crucial role in nuclear-heated safety research. The facility’s flexible design and multi-mission nature saw historic experiments for numerous reactor fuels and transient types but was never specifically adapted to address very-brief pulse transients akin to postulated Light Water Reactor (LWR) Reactivity Initiated Accidents (RIA). Since the behaviors of fuel under these conditions depends strongly on energy input duration and resulting cladding time/temperature response under pellet cladding mechanical interactions, this three-year project was conceived to investigate new pulse-narrowing capabilities. Kinetic models showed incremental improvements for minor facility enhancements including increased reactivity step insertions (to initiate the power pulse) and slightly-increased transient rod drive speed for pulse termination (“clipping”). Replacing peak fuel assemblies, repositioning non-transient control rods to hold down the “hot side” of the core, and balancing against required excess reactivity needs, the limiting fuel assembly power can be reduced by ~20 %. Furthermore, this is a remarkable discovery of latent capability in TREAT, not only in enabling the subject capabilities for reduced pulse widths, but also significantly “uprating” the core’s transient energy capacity. Incremental improvements can likely enhance TREAT’s capability into BWR-relevant missions; briefer PWR pulse shapes can only be achieved with an advanced clipping system. Helium-3 ( 3 He) was found to offer the greatest benefits for clipping design and overall performance. A unique concept showed great promise for enabling a 3 He-based system with a reasonable cost; this design concept will likely become the focal point of future work.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2021

Sub-Sampled Imaging for STEM: Maximising Image Speed, Resolution and Precision Through Reconstruction Parameter Refinement

Sub-sampling during image acquisition in scanning transmission electron microscopy (STEM) has been shown to provide a means to increase the overall speed of acquisition while at the same time providing an efficient means to control the dose, dose rate and dose overlap delivered to the sample. In this paper, we discuss specifically the parameters used to reconstruct sub-sampled images and highlight their effect on inpainting using the beta-process factor analysis (BPFA) methodology. The selection of the main control parameters can have a significant effect on the resolution, precision and sensitivity of the final inpainted images, and here we demonstrate a method by which these parameters can be optimised for any image in STEM. As part of this paper, we also provide a link to open source code and a tutorial on its use, whereby these parameters can be tested for any datasets. When coupled with the hardware necessary to rapidly sub-sample images in STEM, this approach can have significant implications for imaging beam sensitive materials and dynamic processes.

47 OTHER INSTRUMENTATION↗
DOE OSTI2016

Combustion chemistry of ethanol: Ignition and speciation studies in a rapid compression facility [On the combustion chemistry of ethanol: Ignition and speciation studies in a rapid compression facility]

Here, ethanol remains the most important alternative fuel for the transportation sector. This work presents new experimental data on ethanol ignition, including stable species measurements, obtained with the University of Michigan rapid compression facility. Ignition delay times were determined from pressure histories of ignition experiments with stoichiometric ethanol–air mixtures at pressures of ~3–10 atm. Temperatures (880–1150 K) were controlled by varying buffer gas composition (Ar, N 2 , CO 2 ). High-speed imaging was used to record chemiluminescence during the experiments, which showed homogeneous ignition events. The results for ignition delay time agreed well with trends on the basis of previous experimental measurements. Speciation experiments were performed using fast gas sampling and gas chromatography to identify and quantify ethanol and 11 stable intermediate species formed during the ignition delay period. Simulations were carried out using a chemical kinetic mechanism available in the literature, and the agreement with the experimental results for ignition delay time and the intermediate species measured was excellent for the majority of the conditions studied. From the simulation results, ethanol + HO 2 was identified as an important reaction at the experimental conditions for both the ignition delay time and intermediate species measurements. Further studies to improve the accuracy of the rate coefficient for ethanol + HO 2 would improve the predictive understanding of intermediate and low-temperature ethanol combustion.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2020

Enhancing the distribution grid resilience using cyber-physical oriented islanding strategy

The increasing penetration of distributed generations enables an innovative operation paradigm that allows islanded operation to enhance the resilience of the distribution grid. In this study, a cyber-physical oriented islanding strategy is proposed by coordinating centralised and distributed control to achieve seamless islanding transition and operational flexibility in emergency conditions. A cyber-physical control structure is developed to mitigate various disturbances (e.g. emergencies or fluctuations) according to different operation conditions. Specifically, the distributed fault isolation and seamless islanding transition are coordinated to mitigate the outage caused by unplanned islanding, while a secondary control is proposed to support primary control by reducing the power fluctuations during islanded operation. With a rapid response speed, the local cyber-physical devices are coordinated to accomplish islanding separation by selecting a feasible islanded area even under an unplanned islanding situation. A field test was conducted on a practical distribution network in China, and the results demonstrated the effectiveness and feasibility of the proposed islanding strategy.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2024

Microgrid to Microgrid Synchronization with Grid-Forming Inverters: Challenges and Solution

Research on network microgrids has primarily focused on control and optimization. However, application aspects such as microgrid-to-microgrid synchronization have not been fully addressed in existing literature. This paper first addresses the challenges of networking microgrids with grid-forming inverter in droop control. Then, it proposes a pre-synchronization algorithm to improves the synchronization speed and transient stability. To improve the speed, the phase difference between adjacent microgrids is minimized. Transients such as inrush current and oscillations are effectively mitigated by increasing the virtual impedance during interconnection. The proposed strategy allows smooth transitions when reconfiguration of the microgrids is needed. The applicability of this strategy to today’s microgrid systems is demonstrated through a validation in a 480V three-phase network microgrid testbed with commercial-grade inverters, protective devices, and switchgear.

Ferrari Maglia, Max↗