521 research outputs found

    Turbine engine Hot Section Technology (HOST) project

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    The Hot Section Technology (HOST) Project is a NASA-sponsored endeavor to improve the durability of advanced gas turbine engines for commercial and military aircraft. Through improvements in the analytical models and life prediction systems, designs for future hot section components , the combustor and turbine, will be more accurately analyzed and will incorporate features required for longer life in the more hostile operating environment of high performance engines

    An introduction to NASA's turbine engine hot section technology (HOST) project

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    An overview of research to develop and improve the accuracy of current analysis methods so that increased durability can be designed into future engines is presented. Emphasis is placed on improved accuracy in life prediction. Component design, including description of the thermal and aerodynamic environments, the material's mechanical response, the interactions between environmental and structural response, and high temperature instrumentation capable of measuring near-engine environment effects are addressed. Component tests, improved modeling of the physical phenomena, and tests to verify the proved models are also discussed

    Markov dynamic models for long-timescale protein motion

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    Molecular dynamics (MD) simulation is a well-established method for studying protein motion at the atomic scale. However, it is computationally intensive and generates massive amounts of data. One way of addressing the dual challenges of computation efficiency and data analysis is to construct simplified models of long-timescale protein motion from MD simulation data. In this direction, we propose to use Markov models with hidden states, in which the Markovian states represent potentially overlapping probabilistic distributions over protein conformations. We also propose a principled criterion for evaluating the quality of a model by its ability to predict long-timescale protein motions. Our method was tested on 2D synthetic energy landscapes and two extensively studied peptides, alanine dipeptide and the villin headpiece subdomain (HP-35 NleNle). One interesting finding is that although a widely accepted model of alanine dipeptide contains six states, a simpler model with only three states is equally good for predicting long-timescale motions. We also used the constructed Markov models to estimate important kinetic and dynamic quantities for protein folding, in particular, mean first-passage time. The results are consistent with available experimental measurements

    On the Trace Anomaly and the Anomaly Puzzle in N=1 Pure Yang-Mills

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    The trace anomaly of the energy-momentum tensor is usually quoted in the form which is proportional to the beta function of the theory. However, there are in general many definitions of gauge couplings depending on renormalization schemes, and hence many beta functions. In particular, N=1 supersymmetric pure Yang-Mills has the holomorphic gauge coupling whose beta function is one-loop exact, and the canonical gauge coupling whose beta function is given by the Novikov-Shifman-Vainshtein-Zakharov beta function. In this paper, we study which beta function should appear in the trace anomaly in N=1 pure Yang-Mills. We calculate the trace anomaly by employing the N=4 regularization of N=1 pure Yang-Mills. It is shown that the trace anomaly is given by one-loop exact form if the composite operator appearing in the trace anomaly is renormalized in a preferred way. This result gives the simplest resolution to the anomaly puzzle in N=1 pure Yang-Mills. The most important point is to examine in which scheme the quantum action principle is valid, which is crucial in the derivation of the trace anomaly.Comment: 25 pages, 1 figure; v2:slight correction in sec.5, minor addition in appendi

    I Rest My Case! The Possibilities and Limitations of Blockchain-Based IP Protection

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    We have identified, mapped and discussed existing research on Blockchain-based solutions for intellectual property (IP) protection, an investigation that emerged from a case in antibody production for scientific and medical applications. To that end, we have performed a systematic literature review and created an instrument that classifies the contributions according to the materiality of the object they protect (from immaterial to physical), the type of protection (authorship notarization or prevention of illegal use) and the type of research (conceptual or empirical). Our results can be used to understand which avenues to pursue in the effort to create a new generation of more effective technology-assisted IP protection systems, a priority for 152 signatory countries of the patent cooperation treaty

    Pomeron in diffractive processes γ(Q2)pρ0p\gamma^*(Q^2)p\to\rho^0 p and γ(Q2)pγ(Q2)p\gamma^*(Q^2)p\to\gamma^*(Q^2) p at large Q^2: the onset of pQCD

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    We study the reactions γ(Q2)pρ0p\gamma^*(Q^2)p\to\rho^0 p and γ(Q2)pγ(Q2)p\gamma^*(Q^2)p\to\gamma^*(Q^2) p at large Q^2 and W2/Q2W^2/Q^2 and small momentum transfer, κ2\kappa^2_\perp, to the nucleon where the pomeron exchange dominates. At large Q^2 the virtual photon selects a hard qqˉq\bar q pair, thus selecting the hard pomeron component (the BFKL pomeron). The amplitudes for both transverse and longitudinal polarizations of the initial photon and outgoing ρ\rho-meson (photon) are calculated in the framework of the BFKL pomeron exchange. Our calculations show that one cannot expect the early onset of the pure perturbative regime in the discussed diffractive processes: the small interquark distances, ρqqˉ<0.2\rho_{q\bar q} <0.2 fm, start to dominate not earlier than at Q2100GeV2,W2/Q2107Q^2 \simeq 100 GeV^2, W^2/Q^2 \simeq 10^7 in γ(Q2)pρ0p\gamma^*(Q^2)p\to\rho^0 p and Q250GeV2,W2/Q2106Q^2 \simeq 50 GeV^2, W^2/Q^2 \simeq 10^6 in γ(Q2)pγ(Q2)p\gamma^*(Q^2)p\to\gamma^*(Q^2) p.Comment: 20 pages, LaTeX, epsfig.st

    Genomic analysis of Pseudomonas putida: genes in a genome island are crucial for nicotine degradation

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    Nicotine is an important chemical compound in nature that has been regarded as an environmental toxicant causing various preventable diseases. Several bacterial species are adapted to decompose this heterocyclic compound, including Pseudomonas and Arthrobacter. Pseudomonas putida S16 is a bacterium that degrades nicotine through the pyrrolidine pathway, similar to that present in animals. The corresponding late steps of the nicotine degradation pathway in P. putida S16 was first proposed and demonstrated to be from 2,5-dihydroxy-pyridine through the intermediates N-formylmaleamic acid, maleamic acid, maleic acid, and fumaric acid. Genomics of strain S16 revealed that genes located in the largest genome island play a major role in nicotine degradation and may originate from other strains, as suggested by the constructed phylogenetic tree and the results of comparative genomic analysis. The deletion of gene hpo showed that this gene is essential for nicotine degradation. This study defines the mechanism of nicotine degradation
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