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Results for “UNIFIED MODEL”
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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Alternative version of chiral color as alternative to the standard model
In a variant of chiral color with the electroweak gauge group generalized to SU(3){sub L}xU(1) anomaly cancellation occurs more readily than in the SU(2){sub L}xU(1) case. Three families are required by anomaly cancellation and the top family appears nonsequentially.
Constitutive modeling for isotropic materials
The unified constitutive theories for application to typical isotropic cast nickel base supperalloys used for air-cooled turbine blades were evaluated. The specific modeling aspects evaluated were: uniaxial, monotonic, cyclic, creep, relaxation, multiaxial, notch, and thermomechanical behavior. Further development of the constitutive theories to model thermal history effects, refinement of the material test procedures, evaluation of coating effects, and verification of the models in an alternate material will be accomplished in a follow-on for this base program.
Boltzmann hierarchy for the cosmic microwave background at second order including photon polarization
Non-Gaussianity and B-mode polarization are particularly interesting features of the cosmic microwave background, as--at least in the standard model of cosmology--their only sources to first order in cosmological perturbation theory are primordial, possibly generated during inflation. If the primordial sources are small, the question arises how large is the non-Gaussianity and B-mode background induced in second order from the initially Gaussian and scalar perturbations. In this paper we derive the Boltzmann hierarchy for the microwave background photon phase-space distributions at second order in cosmological perturbation theory including the complete polarization information, providing the basis for further numerical studies. As an aside we note that the second-order collision term contains new sources of B-mode polarization and that no polarization persists in the tight-coupling limit.
Primordial black holes and a large hidden sector
In this note we point out that primordial black holes could be much shorter lived than usually assumed if there is a large hidden sector of particles that only interacts gravitationally with the particles of the standard model. The observation of the explosion of one of these black holes would severely constrain the energy scale at which gravity becomes strong.
Anatomy of new physics in B-B mixing
We analyze three different new physics scenarios for {Delta}F=2 flavor-changing neutral currents in the quark sector in the light of recent data on neutral-meson mixing. We parametrize generic new physics contributions to B{sub q}-B{sub q} mixing, q=d, s, in terms of one complex quantity {Delta}{sub q}, while three parameters {Delta}{sub K}{sup tt}, {Delta}{sub K}{sup ct}, and {Delta}{sub K}{sup cc} are needed to describe K-K mixing. In scenario I, we consider uncorrelated new physics contributions in the B{sub d}, B{sub s}, and K sectors. In this scenario, it is only possible to constrain the parameters {Delta}{sub d} and {Delta}{sub s} whereas there are no nontrivial constraints on the kaon parameters. In scenario II, we study the case of minimal flavor violation (MFV) and small bottom Yukawa coupling, where {Delta}{identical_to}{Delta}{sub d}={Delta}{sub s}={Delta}{sub K}{sup tt}. We show that {Delta} must then be real, so that no new CP phases can be accommodated, and express the remaining parameters {Delta}{sub K}{sup cc} and {Delta}{sub K}{sup ct} in terms of {Delta} in this scenario. Scenario III is the generic MFV case with large bottom Yukawa couplings. In this case, the kaon sector is uncorrelated to the B{sub d} and B{sub s} sectors. As in the second scenario one has {Delta}{sub d}={Delta}{sub s{identical_to}{Delta}}, however, now with a complex parameter {Delta}. Our quantitative analyses consist of global Cabibbo-Kobayashi-Maskawa (CKM) fits within the Rfit frequentist statistical approach, determining the standard model parameters and the new physics parameters of the studied scenarios simultaneously. We find that the recent measurements indicating discrepancies with the standard model are well accommodated in Scenarios I and III with new mixing phases, with a slight preference for Scenario I that permits different new CP phases in the B{sub d} and B{sub s} systems. Within our statistical framework, we find evidence of new physics in both B{sub d} and B{sub s} systems. The standard model hypothesis {Delta}{sub d}={Delta}{sub s}=1 is disfavored with p-values of 3.6{sigma} and 3.3{sigma} in Scenarios I and III, respectively. We also present an exhaustive list of numerical predictions in each scenario. In particular, we predict the CP phase in B{sub s}{yields}J/{psi}{phi} and the difference between the B{sub s} and B{sub d} semileptonic asymmetries, which will be both measured by the LHCb experiment.
Benefits of a Unified LaSRS++ Simulation for NAS-Wide and High-Fidelity Modeling
The LaSRS++ high-fidelity vehicle simulation was extended in 2012 to support a NAS-wide simulation mode. Since the initial proof-of-concept, the LaSRS++ NAS-wide simulation is maturing into a research-ready tool. A primary benefit of this new capability is the consolidation of the two modeling paradigms under a single framework to save cost, facilitate iterative concept testing between the two tools, and to promote communication and model sharing between user communities at Langley. Specific benefits of each type of modeling are discussed along with the expected benefits of the unified framework. Current capability details of the LaSRS++ NAS-wide simulations are provided, including the visualization tool, live data interface, trajectory generators, terminal routing for arrivals and departures, maneuvering, re-routing, navigation, winds, and turbulence. The plan for future development is also described.
A proposed framework for the development and qualitative evaluation of West Nile virus models and their application to local public health decision-making
West Nile virus (WNV) is a globally distributed mosquito-borne virus of great public health concern. The number of WNV human cases and mosquito infection patterns vary in space and time. Many statistical models have been developed to understand and predict WNV geographic and temporal dynamics. However, these modeling efforts have been disjointed with little model comparison and inconsistent validation. In this paper, we describe a framework to unify and standardize WNV modeling efforts nationwide. WNV risk, detection, or warning models for this review were solicited from active research groups working in different regions of the United States. A total of 13 models were selected and described. The spatial and temporal scales of each model were compared to guide the timing and the locations for mosquito and virus surveillance, to support mosquito vector control decisions, and to assist in conducting public health outreach campaigns at multiple scales of decision-making. Our overarching goal is to bridge the existing gap between model development, which is usually conducted as an academic exercise, and practical model applications, which occur at state, tribal, local, or territorial public health and mosquito control agency levels. The proposed model assessment and comparison framework helps clarify the value of individual models for decision-making and identifies the appropriate temporal and spatial scope of each model. This qualitative evaluation clearly identifies gaps in linking models to applied decisions and sets the stage for a quantitative comparison of models. Specifically, whereas many coarse-grained models (county resolution or greater) have been developed, the greatest need is for fine-grained, short-term planning models (m–km, days–weeks) that remain scarce. We further recommend quantifying the value of information for each decision to identify decisions that would benefit most from model input.
A Flexible Atmospheric Modeling Framework for the CESM
We have created two global dynamical cores based on the unified system of equations and Z-grid staggering on an icosahedral grid, which are collectively called UZIM (Unified Z-grid Icosahedral Model). The z-coordinate version (UZIM-height) can be run in hydrostatic and nonhydrostatic modes. The sigma-coordinate version (UZIM-sigma) runs in only hydrostatic mode. The super-parameterization has been included as a physics option in both models. The UZIM versions with the super-parameterization are called SUZI. With SUZI-height, we have completed aquaplanet runs. With SUZI-sigma, we are making aquaplanet runs and realistic climate simulations. SUZI-sigma includes realistic topography and a SiB3 model to parameterize the land-surface processes.
The NuTeV anomaly: solved?
The NuTeV extraction of the Weinberg angle is reported to differ by 3{sigma} from measurements at the Z pole. We review various effects within the Standard Model, and conclude that corrections from these effects bring the NuTeV measurement within 1{sigma} of the expected result.
Two Higgs doublet model of type II facing flavor physics data
We discuss tests of the charged Higgs sector of the two Higgs doublet model (2HDM) of type II in the light of recent flavor physics data. Particular attention is paid to recent measurement of purely leptonic decays of heavy-light mesons, which depart more or less significantly from the standard model (SM) predictions. We derive constraints on the parameters of the 2HDM type II from leptonic and semileptonic {Delta}F=1 decays as well as loop processes (b{yields}s{gamma}, BB mixing, or Z{yields}bb) sensitive to charged Higgs contributions. The outcome of this work is that while 2HDM type II can fit the individual observable through fine-tuning schemes, in a combined analysis it does not perform better than the standard model by favoring a decoupling solution. Assuming that 2HDM type II is realized in nature, constraints on its parameters (m{sub H}{sup +} and tan{beta}) are derived. A limit on the charged Higgs mass m{sub H}{sup +}>316 GeV at 95% CL is obtained irrespective of the value of tan{beta}. This limit is dominated by the b{yields}s{gamma} branching ratio measurement. All results have been obtained with the CKMfitter analysis package, featuring the frequentist statistical approach Rfit to handle theoretical uncertainties.
Tight connection between direct and indirect detection of dark matter through Higgs portal couplings to a hidden sector
We present a hidden Abelian extension of the standard model including a complex scalar as a dark matter candidate and a light scalar acting as a long range force carrier between dark matter particles. The Sommerfeld enhanced annihilation cross section of the dark matter explains the observed cosmic ray excesses. The light scalar field also gives rise to potentially large cross sections of dark matter on the nucleon, therefore providing an interesting way to probe this model simultaneously at direct and indirect dark matter search experiments. We constrain the parameter space of the model by taking into account the CDMS-II exclusion limit as well as PAMELA and Fermi LAT data.
2017 Algae Harmonization Study: Evaluating the Potential for Future Algal Biofuel Costs, Sustainability, and Resource Assessment from Harmonized Modeling
To present a more unified picture of the long-term future potential for algal biofuels and the goals that must be met to reach that potential, four algae modeling groups collaborated to harmonize respective models for resource assessment (Pacific Northwest National Laboratory), techno-economic analysis (National Renewable Energy Laboratory and Pacific Northwest National Laboratory), and life-cycle analysis (Argonne National Laboratory) of algal biomass production and conversion processes. In contrast to prior harmonization studies that this group has previously conducted, which focused on establishing benchmarks attributed to current performance at the time, the primary intent of the present harmonization study was to project these models to forward-looking targets that must be achieved to reduce fuel costs and greenhouse gas emission profiles to Bioenergy Technologies Office target levels, subject to specific location constraints imposed by resource assessment modeling and thus national-scale fuel output potential (i.e., billion gallons gasoline equivalent per year, or BGGE/yr). In all, while based on a number of aspirational goals not yet demonstrated but plausible to achieve over coming years, the harmonized outputs indicate promising potential for algal biofuels to make a significant contribution to the U.S. fuels market, based on substantial quantities of biomass (104-235 MM tons/yr) projected to be available at costs below 700/ton (generally below 500/ton for freshwater cultivation). While these costs are still significantly higher than terrestrial biomass cost targets, the propensity for capturing high fuel yields and/or high-value tailored coproducts from algal biomass is shown here to provide plausible paths to achieve future targets for cost and sustainability metrics at meaningful volumes.
Shepherding Metadata Through the Building Lifecycle
Many different digital representations of a building are produced over the course of its lifecycle. These representations contain the metadata required to support different stages of the building, from initial planning and design, to construction and commissioning, through operations, audits, retrofits and maintenance. However, because of differences in the semantics, structure and syntax of these representations, the metadata they contain is not interoperable. We present a novel method for leveraging these representations to create a unified, authoritative Brick metadata model for a building that can be continually maintained over the course of the building lifecycle. A simple synchronization protocol relays inferred Brick metadata from existing metadata sources such as gbXML, BuildingSync, Project Haystack and Modelica to a central integration server, which merges the metadata into a valid Brick model.
Unified Wind-Wave Growth and Spectrum Functions for All Water Depths: Field Observations and Model Results
Abstract Wind-wave development is governed by the fetch- or duration-limited growth principle that is expressed as a pair of similarity functions relating the dimensionless elevation variance (wave energy) and spectral peak frequency to fetch or duration. Combining the pair of similarity functions, the fetch or duration variable can be removed to form a dimensionless function of elevation variance and spectral peak frequency, which is interpreted as the wave energy evolution with wave age. The relationship is initially developed for quasi-neural stability and quasi-steady wind forcing conditions. Further analyses show that the same fetch, duration, and wave-age similarity functions are applicable to unsteady wind forcing conditions, including rapidly accelerating and decelerating mountain gap wind episodes and tropical cyclone (TC) wind fields. Here it is shown that with the dimensionless frequency converted to dimensionless wavenumber using the surface wave dispersion relationship, the same similarity function is applicable in all water depths. Field data collected in shallow to deep waters and mild to TC wind conditions and synthetic data generated by spectrum model computations are assembled to illustrate the applicability. For the simulation work, the finite-depth wind-wave spectrum model and its shoaling function are formulated for variable spectral slopes. Given wind speed, wave age, and water depth, the measured and spectrum-computed significant wave heights and the associated growth parameters are in good agreement in forcing conditions from mild to TC winds and in all depths from deep ocean to shallow lake. Significance Statement This paper presents a growth function and spectrum model to describe wind-wave development in all water depths. Their applicability covers a wide range of wind forcing conditions including steady, accelerating, decelerating, and tropical cyclone events. Support for the unified spectrum model and growth function is presented with field observations and numerical computations.
Virtual Synchronous Machine Grid-Forming Inverter Model Specification (REGFM_B1)
This report describes a generic virtual synchronous machine (VSM) grid-forming inverter (GFM) model - REGFM_B1. The initial model specification was proposed by Pacific Northwest National Laboratory (PNNL), General Electric (GE), and Electric Power Research Institute (EPRI). Siemens Gamesa Renewable Energy (SGRE) also provided inputs to the specification. The model specification has been revised multiple times based on the discussions between all the contributors listed in this report. This work was funded by the Universal Interoperability for Grid-Forming Inverters (UNIFI) Consortium. This generic model is developed to help the utility industry understand the concept of VSM GFMs. The model could be used to represent equipment for long-term planning studies where vendor-specific models are not available. As equipment mature and improve, generic models will be updated to capture the new functionalities of GFMs. It is not intended that these models will always remain representative of all future GFM technologies.
Large loop effects of extra supersymmetric Higgs doublets to CP violation in B{sup 0} mixing
We consider more than one pair of SU(2){sub L} doublet Higgs supermultiplets in a generic supersymmetric extension of the standard model, and calculate their one-loop contributions to the soft mass insertions {delta}{sub LL} etc. We find that, if large supersymmetry breaking in this sector is realized, the loop effects can give rise to large contributions to the soft mass insertions, meaning that they can generate large flavor-changing neutral currents and CP violations. We apply our result to a recently proposed model based on the discrete Q{sub 6} family group, and calculate the nondiagonal matrix element M{sub 12} of the neutral meson systems. We focus our attention on the extra phases {phi}{sub d,s}{sup {Delta}}in B{sub d,s} mixing and flavor-specific CP asymmetries a{sub sl}{sup d,s} in neutral B decays and obtain values that can be about 1 order of magnitude larger than the standard model predictions. Our final results are comparable with the recent experimental observations at D0 and CDF, but they are still about a factor of 5 smaller than the recently measured dimuon asymmetry from D0.
A CLC-ec1 mutant reveals global conformational change and suggests a unifying mechanism for the CLC Cl–/H+ transport cycle
Among coupled exchangers, CLCs uniquely catalyze the exchange of oppositely charged ions (Cl– for H+). Transport-cycle models to describe and explain this unusual mechanism have been proposed based on known CLC structures. While the proposed models harmonize with many experimental findings, gaps and inconsistencies in our understanding have remained. One limitation has been that global conformational change – which occurs in all conventional transporter mechanisms – has not been observed in any high-resolution structure. Here, we describe the 2.6 Å structure of a CLC mutant designed to mimic the fully H+-loaded transporter. This structure reveals a global conformational change to improve accessibility for the Cl– substrate from the extracellular side and new conformations for two key glutamate residues. Together with DEER measurements, MD simulations, and functional studies, this new structure provides evidence for a unified model of H+/Cl– transport that reconciles existing data on all CLC-type proteins.