Search NASA⌕ Search

SEARCH · Search NASA

Results for “dynamic windows”

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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Recovery Act: Electrochromic Glazing Technology: Improved Performance, Lower Price (Final Report)

The growing dependency of the US on energy imports and anticipated further increases in energy prices reinforce the concerns about meeting the energy demand in the future and one element of a secure energy future is conservation. It is estimated that the buildings sector represents 40% of the US's total energy consumption. And buildings produce as much as one third of the greenhouse gas emissions primarily through fossil fuel usage during their operational phase. A significant fraction of this energy usage is simply due to inefficient window technology. Electrochromic (EC) windows allow electronic control of their optical properties so that the transparency to light can be adjusted from clear to dark. This ability to control the amount of solar energy allowed into the building can be advantageously used to minimize lighting, heating and air conditioning costs. Currently, the penetration of EC windows into the marketplace is extremely small, and consequently there is a huge opportunity for energy savings if this market can be expanded. In order to increase the potential energy savings it is necessary to increase the quantity of EC windows in operation. Additionally, any incremental improvement in the energy performance of each window will add to the potential energy savings. The overall goals of this project were therefore to improve the energy performance and lower the cost of dynamic (EC) smart windows for residential and commercial building applications. This project is obviously of benefit to the public by addressing two major areas: lowering the cost and improving the energy performance of EC glazings. The high level goals for these activities were: (i) to improve the range between the clear and the tinted state, (ii) reduce the price of EC windows by utilizing lower cost materials, (iii) lowering the U-Value, and (iv) ensure the proposed changes have no detrimental effect to the proven durability of the window. SAGE Electrochromics Inc. is the only company in the US which has a track record of producing EC windows, and presently has a small operational factory in Faribault MN which is shipping products throughout the world. There is a much larger factory currently under construction close by. This project was targeted specifically to address the issues outlined above, with a view to implementation on the new high volume manufacturing facility. Each of the Tasks which were addressed in this project is relatively straightforward to implement in this new facility and so the benefits of the work will be realized quickly. The research described here has helped to understand and provide solutions to several interesting and previously unresolved issues of the technology as well as make progress in areas which will have a significant impact on energy saving. In particular several materials improvements have been made, and tasks related to throughput and yield improvements have been completed. All of this has been accomplished without any detrimental effect on the proven durability of the SageGlass EC device. The project was divided into four main areas: 1. Improvement of the Properties of the EC device by material enhancements (Task 2); 2. Reduce the cost of production by improving the efficiency and yields of some key manufacturing processes (Task 3); 3. Further reduce the cost by significant modifications to the structure of the device (Task 4); 4. Ensure the durability of the EC device is not affected by any of the changes resulting from these activities (Task 5). A detailed description of the activities carried out in these areas is given in the following report, along with the aims and goals of the work. We will see that we have completed Tasks 2 and 3 fully, and the durability of the resulting device structure has been unaffected. Some of Task 4 was not carried out because of difficulties with integrating the installation of the required targets into the production coater due to external constraints not related to this project. We will also see that the durability of the devices produced as a result of this work was largely unaffected by the changes made here, and so we can conclude that the objectives of Task 5 have also been fulfilled. As a result, the future production of EC windows has benefited greatly from this work. We anticipate higher volumes and better yields for devices with an improved EC performance from the new high volume manufacturing facility currently under construction at SAGE.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2024

A windowed mean trajectory approximation for condensed phase dynamics

We propose a trajectory-based quasi-classical method for approximating dynamics in condensed phase systems. Building upon the previously developed optimized mean trajectory approximation that has been used to compute linear and nonlinear spectra, we borrow some ideas from filtering trajectory methods to obtain a novel semiclassical method for the dynamical propagation of density matrices. This new approximation is tested rigorously against standard multistate electronic models, spin-boson models, and models of the Fenna–Matthews–Olson complex. For dissipative systems, the current method is significantly better or as good as many other semiclassical methods available, especially at low temperatures and for off-diagonal density matrix elements, whereas for scattering models, the current method bears similar limitations as mean-field propagation schemes. All results are tested against the numerically exact hierarchical equations of motion method. In conclusion, the new method shows excellent agreement across various parameter regimes with numerically exact results, highlighting the robustness and accuracy of our approach.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Use of dMLC for implementation of dynamic respiratory-gated radiation therapy

Purpose: To simulate and evaluate the use of dynamic multileaf collimators (dMLC) in respiratory gating to compensate for baseline drift.Methods: Tumor motion tracking data from 30 lung tumors over 322 treatment fractions was analyzed with the finite state model. A dynamic respiratory gating window was established in real-time by determining the average positions during the previous two end-of-expiration breathing phases and centering the dMLC aperture on a weighted average of these positions. A simulated dMLC with physical motion constraints was used in dynamic gating treatment simulations. Fluence maps were created to provide a statistical description of radiation delivery for each fraction. Duty cycle was also calculated for each fraction.Results: The average duty cycle was 2.3% greater under dynamic gating conditions. Dynamic gating also showed higher fluences and less tumor obstruction. Additionally, dynamic gating required fewer beam toggles and each delivery period was longer on average than with static gating.Conclusions: The use of dynamic gating showed better performance than static gating and the physical constraints of a dMLC were shown to not be an impediment to dynamic gating.

61 RADIATION PROTECTION AND DOSIMETRY↗
NASA NTRS1991

Predicting chaos for infinite dimensional dynamical systems: The Kuramoto-Sivashinsky equation, a case study

The results of extensive computations are presented in order to accurately characterize transitions to chaos for the Kuramoto-Sivashinsky equation. In particular, the oscillatory dynamics in a window that supports a complete sequence of period doubling bifurcations preceding chaos is followed. As many as thirteen period doublings are followed and used to compute the Feigenbaum number for the cascade and so enable, for the first time, an accurate numerical evaluation of the theory of universal behavior of nonlinear systems, for an infinite dimensional dynamical system. Furthermore, the dynamics at the threshold of chaos exhibit a fractal behavior which is demonstrated and used to compute a universal scaling factor that enables the self-similar continuation of the solution into a chaotic regime.

Smyrlis, Yiorgos S.↗
DOE OSTI2015

WE-D-BRA-03: Four-Dimensional Dose Reconstruction Through Retrospective Phase Determination Using Cine Images of Electronic Portal Imaging Device

Purpose: To test a method to reconstruct a four-dimensional (4D) dose distribution using the correlation of pre-calculated 4D electronic portal imaging device (EPID) images and measured cine-EPID images. Methods: 1. A phantom designed to simulate a tumor in lung (a polystyrene block with 3.0 cm diameter embedded in cork) was placed on a sinusoidally moving platform with 2 cm amplitude and 4 sec/cycle. Ten-phase 4D CT images were acquired for treatment planning and dose reconstruction. A 6MV photon beam was irradiated on the phantom with static (field size=5×8.5 cm{sup 2}) and dynamic fields (sliding windows, 10×10 cm{sup 2}, X1 MLC closing in parallel with the tumor movement). 2. 4D and 3D doses were calculated forwardly on PTV (1 cm margin). 3. Dose images on EPID under the fields were calculated for 10 phases. 4. Cine EPID images were acquired during irradiation. 5. Their acquisition times were correlated to the phases of the phantom at which irradiation occurred by inter-comparing calculated “reference” EPID images with measured images (2D gamma comparison). For the dynamic beam, the tumor was hidden under MLCs during a portion of irradiation time; the correlation performed when the tumor was visible was extrapolated. 6. Dose for each phase was reconstructed on the 4D CT images and summed over all phases. The summation was compared with forwardly calculated 4D and 3D dose distributions. Monte Carlo methods were used for all calculations. Results: For the open and dynamic beams, the 4D reconstructed doses showed the pass rates of 92.7 % and 100 %, respectively, at the isocenter plane given 3% / 3 mm criteria. The better agreement of the dynamic beam was from its dose gradient which blurred the otherwise sharp difference between forward and reconstructed doses. This also contributed slightly better agreement in DVH of PTV. Conclusion: The feasibility of 4D reconstruction was demonstrated.

60 APPLIED LIFE SCIENCES↗
NASA NTRS2013

Investigation of Control Inceptor Dynamics and Effect on Human Subject Performance

The control inceptor used in a vehicle simulation is an important part of adequately representing the dynamics of the vehicle. The inceptor characteristics are typically based on a second order spring mass damper system with damping, force gradient, breakout force, and natural frequency parameters. Changing these parameters can have a great effect on pilot control of the vehicle. A quasi transfer of training experiment was performed employing a high fidelity and a low fidelity control inceptor. A disturbance compensatory task was employed which involved a simple horizon line disturbed in roll by a sum of sinusoids presented in an out-the-window display. Vehicle dynamics were modeled as 1/s and 1/s2. The task was to maintain level flight. Twenty subjects were divided between the high and the low fidelity training groups. Each group was trained to a performance asymptote, and then transferred to the high fidelity simulation. RMS tracking error, a PSD analysis, and a workload analysis were performed to quantify the transfer of training effect. Quantitative results of the experiments show that there is no significant difference between the high and low fidelity training groups for 1/s plant dynamics. For 1/s2 plant dynamics there is a greater difference in tracking performance and PSD; and the subjects are less correlated with the input disturbance function

Stanco, Anthony A.↗
DOE OSTI2019

Heterogeneous local dynamics revealed by classification analysis of spatially disaggregated time series data

Time series data provide a crucial window into infectious disease dynamics, yet their utility is often limited by the spatially aggregated form in which they are presented. When working with time series data, violating the implicit assumption of homogeneous dynamics below the scale of spatial aggregation could bias inferences about underlying processes. We tested this assumption in the context of the 2015–2016 Zika epidemic in Colombia, where time series of weekly case reports were available at national, departmental, and municipal scales. First, we performed a descriptive analysis, which showed that the timing of departmental-level epidemic peaks varied by three months and that departmental-level estimates of the time-varying reproduction number, R(t), showed patterns that were distinct from a national-level estimate. Second, we applied a classification algorithm to six features of proportional cumulative incidence curves, which showed that variability in epidemic duration, the length of the epidemic tail, and consistency with a cumulative normal density curve made the greatest contributions to distinguishing groups. Third, we applied this classification algorithm to data simulated with a stochastic transmission model, which showed that group assignments were consistent with simulated differences in the basic reproduction number, R0. This result, along with associations between spatial drivers of transmission and group assignments based on observed data, suggests that the classification algorithm is capable of detecting differences in temporal patterns that are associated with differences in underlying drivers of incidence patterns. Overall, this diversity of temporal patterns at local scales underscores the value of spatially disaggregated time series data.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2024

Crescendo beyond the horizon: More gravitational waves from domain walls bounded by inflated cosmic strings

Gravitational-wave (GW) signals offer a unique window into the dynamics of the early universe. GWs may be generated by the topological defects produced in the early universe, which contain information on the symmetry of UV physics. We consider the case in which a two-step phase transition produces a network of domain walls bounded by cosmic strings. Specifically, we focus on the case in which there is a hierarchy in the symmetry-breaking scales, and a period of inflation pushes the cosmic string generated in the first phase transition outside the horizon before the second phase transition. We show that the GW signal from the evolution and collapse of this string-wall network has a unique spectrum, and the resulting signal strength can be sizeable. In particular, depending on the model parameters, the resulting signal can show up in a broad range of frequencies and can be discovered by a multitude of future probes, including the pulsar timing arrays and space- and ground-based GW observatories. As an example that naturally gives rise to this scenario, we present a model with the first phase transition followed by a brief period of thermal inflation driven by the field responsible for the second stage of symmetry breaking. Here, the model can be embedded into a supersymmetric setup, which provides a natural realization of this scenario. In this case, the successful detection of the peak of the GW spectrum probes the soft supersymmetry breaking scale and the wall tension.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Development of intelligent control module for the J-TEXT electron cyclotron emission imaging system

An Electron Cyclotron Emission Imaging (ECEI) system has been developed on the J-TEXT tokamak and employed for the multi-dimensional electron temperature fluctuation imaging measurement in 2019 campaign. The intelligent control module has been developed and been used to flexibly setup the 256-channel ECEI system configurations for different plasma scenarios. The adjustments of key parameters are merged in this module including size and position of the geometric observation window, and the dynamic range of the signal and image resolution. The user-friendly interface is also developed for the tokamak operator to set the ECEI system focusing on physics interested region. Furthermore, this module is installed close to the diagnostic system around the J-TEXT tokamak, which can be remotely controlled by authorized operators in the control room. It significantly improves ECEI flexibility and stability, and also keeps the operation technician away from the harsh radiation environment.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2012

Excited light meson spectroscopy from lattice QCD

I report on recent progress in calculating excited meson spectra using lattice QCD, emphasizing results and phenomenology. With novel techniques we can now extract extensive spectra of excited mesons with high statistical precision, including spin-four states and those with exotic quantum numbers. As well as isovector meson spectra, I will present new calculations of the spectrum of excited light isoscalar mesons, something that has up to now been a challenge for lattice QCD. I show determinations of the flavor content of these mesons, including the eta-eta' mixing angle, providing a window on annihilation dynamics in QCD. I will also discuss recent work on using lattice QCD to map out the energy-dependent phase shift in pi-pi scattering and future applications of the methodology to the study of resonances and decays.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2021

Lasergate: A windowless gas target for enhanced laser preheat in magnetized liner inertial fusion

At the Z Facility at Sandia National Laboratories, the magnetized liner inertial fusion (MagLIF) program aims to study the inertial confinement fusion in deuterium-filled gas cells by implementing a three-step process on the fuel: premagnetization, laser preheat, and Z-pinch compression. In the laser preheat stage, the Z-Beamlet laser focuses through a thin polyimide window to enter the gas cell and heat the fusion fuel. However, it is known that the presence of the few μm thick window reduces the amount of laser energy that enters the gas and causes window material to mix into the fuel. These effects are detrimental to achieving fusion; therefore, a windowless target is desired. The Lasergate concept is designed to accomplish this by “cutting” the window and allowing the interior gas pressure to push the window material out of the beam path just before the heating laser arrives. In this work, we present the proof-of-principle experiments to evaluate a laser-cutting approach to Lasergate and explore the subsequent window and gas dynamics. Further, an experimental comparison of gas preheat with and without Lasergate gives clear indications of an energy deposition advantage using the Lasergate concept, as well as other observed and hypothesized benefits. While Lasergate was conceived with MagLIF in mind, the method is applicable to any laser or diagnostic application requiring direct line of sight to the interior of gas cell targets.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

Achievable noise performance of spectroscopic prototype DEPFET detectors

A new generation of spectroscopic X-ray DEPFET detectors has been produced here in the course of the detector development for the Wide Field Imager (WFI) of Athena. These devices served to perform a detailed analysis of the noise composition, which was enabled by the development of appropriate test algorithms. A result of the analysis is the distinction of different components, which sum up to the total noise. In particular the contribution of shot noise, white noise and 1/f noise to the readout noise is determined as well as the signal noise caused by the generation of charge carriers. The resulting parametrization enables the adaptation and optimization of operation modes to given purposes. The studied prototype detectors included 64×64 pixels with a linear gate design and provided an excellent noise, below 1.6 e - ENC at a readout time faster than 10 μs/pixel and a temperature of -80 °C in rolling-shutter operation. This performance is enabled by an extended signal integration time. A further noise reduction is prevented by the signal noise, caused by charge carrier generation. In order to demonstrate the low noise properties of the DEPFET transistor, the measurement conditions were adapted and a noise of 0.95 e - ENC was measured at the expense of the sensor size—by operating only parts of the sensor in window mode—and dynamic range—by using the Al Kα line at about 1.49 keV for calibration.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

Shock-induced melting of [100] lithium fluoride: Sound speed and Hugoniot measurements to 230 GPa

Although [100] lithium flouride (LiF) is the most widely used optical window material in dynamic compression experiments, its high stress (>100 GPa) shock compression response, including melting, is not well understood. To address this need, we measured wave profiles in plate impact experiments to determine the Hugoniot states and longitudinal sound speeds in [100] LiF crystals shock compressed to 231 GPa. The measured peak states are fitted well by a linear shock velocity-particle velocity relation, providing an accurate determination of the LiF Hugoniot curve to significantly higher stresses than previous experiments. The longitudinal sound speeds show a near linear increase with density compression to 182 GPa. Between 182 GPa and 195 GPa, the sound speed and the longitudinal modulus decrease abruptly, due to shock-induced melting. The increasing sound speeds and moduli at higher stresses suggest that shock compressed LiF is fully liquid at 195 GPa and above, allowing determination of the Gruneisen parameter for liquid LiF. Here, the melt stress determined here differs from that predicted by current multiphase equations of state for LiF. Our results provide important insight into the high stress solid and liquid states of shock compressed LiF and point to the need for an improved multiphase equation of state at high pressures and high temperatures.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Melting and transport properties of Al 2⁢ O 3 at extreme conditions

The high-pressure, temperature phase diagram and transport properties of materials are of broad interest to planetary sciences and high-energy-density sciences and applications. Alumina (Al 2 O 3 ) or its various forms (e.g., solutions with other oxides or silicates) are important constituents in Earth’s and super-Earths’ mantles, common window materials in dynamic compression experiments, and standard pressure calibrators in diamond-anvil-cell experiments. Its structures and transport properties are of particular importance but have not been well studied at above 100 GPa pressures. Based on extensive first-principles molecular dynamics calculations, we obtain atomic level insights on structural differences and accurate results on electrical conductivity (σ dc ), thermal conductivity (κ), and reflectivity of Al 2 O 3 in several phases at pressures of ~130–1300 GPa and temperatures of 4000–20,000 K. We find the solid-to-liquid state changes of Al 2 O 3 are accompanied by an insulator-to-semimetal transition with enhanced σ dc and κ, which is similar to other silicates and oxides and can facilitate magnetic field generation in deep interiors of rocky planets. We also find the solid-to-solid transition (from Rh 2 O 3 (II) to CaIrO 3 ) is accompanied by negligible changes in σ dc and κ at 160 GPa, contrary to previous expectations, whereas another higher pressure phase transition (CaIrO 3 to U 2 S 3 at 450 GPa) is associated with increases in σ dc and κ. Furthermore, we show the transport properties can be enhanced by oxygen vacancy in Al 2 O 3 , but are not significantly affected by forming solutions with MgSiO 3 , particularly when in the solid states.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Ab initiomany-body Green's function calculations of optical properties of LiF at high pressures

We present density functional theory (DFT) + quasiparticle self-energy (G 0 W 0 )+ Bethe-Salpeter calculations of the real and imaginary parts of the long-wavelength dielectric function of LiF between ambient pressure and P=5 Mbars. While the optical absorption spectrum is predicted to show dramatic pressure-dependent features above the optical gap, the index of refraction well below the gap is shown to exhibit the same trends as that seen in both DFT calculations and experiment: a roughly linear increase with density. This increase does not result from a decrease in the band gap, but rather follows from the increase in oscillator strength which counteracts a smaller increase in band gap with P. Our calculations also suggest that the index of refraction (for visible and near-UV light) of the higher-T B 2 phase should be quite close to that of the B 1 (ambient crystalline) phase. These findings may be of interest to researchers who use LiF as a window material in dynamic compression experiments.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

Light new physics in B → K ( * ) ν ν ¯ ?

The study of the rare decays B → K ( * ) ν ν ¯ offers a window into the dynamics operating at the electroweak scale, allowing studies of the Standard Model and searches for heavy new physics. However, the analysis of these decays is also potentially sensitive to the on shell production of new light bosons X through the process B → K ( * ) X . In particular, Belle II has recently measured B + → K + ν ν ¯ , finding a 2.8 σ excess under the assumption of heavy new physics. Since this excess is rather localized in the kaon energy, a fit that includes the decay mode B + → K + X to the kinematic distributions prefers m X ≈ 2 GeV with branching fraction Br [ B → K X ] = ( 8.8 ± 2.5 ) × 10 − 6 and a significance of ≈ 3.6 σ . However, no excess was found in the measurements of B → K ( * ) ν ν ¯ , and a global analysis of the Belle II and data leads to Br [ B → K X ] = ( 5.1 ± 2.1 ) × 10 − 6 with a reduced significance of ≈ 2.4 σ . We then study various simplified dark-flavored models and present a possible UV completion based on a gauged B 3 − L 3 symmetry, highlighting the discovery potential of dedicated searches for B → K ( * ) X at Belle II. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2022

Postquantum Quench Growth of Renyi Entropies in Low-Dimensional Continuum Bosonic Systems

The growth of Renyi entropies after the injection of energy into a correlated system provides a window upon the dynamics of its entanglement properties. Here we develop a simulation scheme by which this growth can be determined in Luttinger liquids systems with arbitrary interactions, even those introducing gaps into the liquid. We apply this scheme to an experimentally relevant quench in the sine-Gordon field theory. While for short times we provide analytic expressions for the growth of the second and third Renyi entropy, to access longer times, we combine our scheme with truncated spectrum methods.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Untargeted Exometabolomics Provides a Powerful Approach to Investigate Biogeochemical Hotspots with Vegetation and Polygon Type in Arctic Tundra Soils

Rising temperatures in the Arctic have led to the thawing of tundra soils, which is rapidly changing terrain, hydrology, and plant and microbial communities, causing hotspots of biogeochemical activity across the landscape. Despite this, little is known about how nutrient-rich low molecular weight dissolved organic matter (LMW DOM) varies within and across tundra ecosystems. Using a high-resolution nano-liquid chromatography-mass spectrometry (LC/MS) approach, we characterized the composition and availability of LMW DOM from high-centered polygons (HCP) and low-centered polygons (LCP) with Eriophorum angustifolium or Carex aquatilis as the dominant vegetation. Over 3000 unique features (i.e., discrete mass/charge ions) were detected; 521 were identified as differentially abundant between polygonal types and 217 were putatively annotated using high mass accuracy MS data. While polygon type was a strong predictor of LMW DOM composition and availability, vegetation and soil depth were also important drivers. Extensive evidence was found for enhanced microbial processing at the LCP sites, which were dominated by Carex plant species. We detected significant differences between polygon types with varying aboveground landscape features or properties, and hotspots of biogeochemical activity, indicating LMW DOM, as quantified by untargeted exometabolomics, provides a window into the dynamic complex interactions between landscape topography, vegetation, and organic matter cycling in Arctic polygonal tundra soils.

58 GEOSCIENCES↗