Littérature scientifique sur le sujet « Variance profile »
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Articles de revues sur le sujet "Variance profile"
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Luati, Alessandra, Tommaso Proietti et Marco Reale. « The Variance Profile ». Journal of the American Statistical Association 107, no 498 (juin 2012) : 607–21. http://dx.doi.org/10.1080/01621459.2012.682832.
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Soleimanian, V., et S. R. Aghdaee. « Comparison methods of variance and line profile analysis for the evaluation of microstructures of materials ». Powder Diffraction 23, no 1 (mars 2008) : 41–51. http://dx.doi.org/10.1154/1.2888763.
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A comparison of different methods of X-ray diffraction analysis for the determination of crystallite size and microstrain; namely, line profile analysis, Rietveld refinement, and three approaches based on the variance method, is presented. The analyses have been applied to data collected on a ceria sample prepared by the IUCr Commission on Powder Diffraction. In the variance method, split Pearson VII, the Voigt function, and its approximation pseudo-Voigt function were fitted to X-ray diffraction line profiles. Based on the fitting results, the variances of line profiles were calculated and then the crystallite size and root mean square strain were obtained from variance coefficients. A SS plot of Langford as well as a Fourier analysis and Rietveld refinement have been carried out. The average crystallite size and microstrain were determined. The values of area-weighted domain size determined from the variance method are in agreement with those obtained from line profile analysis within a single (largest) standard uncertainty, and the volume-weighted domain sizes derived from the SS plot, Fourier size distribution, and Rietveld refinement agree within a single standard uncertainty. The results of rms strain calculated from variance and Pearson VII shape function and those from Rietveld refinements fall within a single esd. However, the variance method in conjunction with pseudo-Voigt and Voigt functions produce rms strains substantially larger than those determined from line profile analysis and Rietveld refinements.
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Raymond, Mark R., et Zhehan Jiang. « Indices of Subscore Utility for Individuals and Subgroups Based on Multivariate Generalizability Theory ». Educational and Psychological Measurement 80, no 1 (16 mai 2019) : 67–90. http://dx.doi.org/10.1177/0013164419846936.
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Conventional methods for evaluating the utility of subscores rely on traditional indices of reliability and on correlations among subscores. One limitation of correlational methods is that they do not explicitly consider variation in subtest means. An exception is an index of score profile reliability designated as [Formula: see text], which quantifies the ratio of true score profile variance to observed score profile variance. [Formula: see text] has been shown to be more sensitive than correlational methods to group differences in score profile utility. However, it is a group average, representing the expected value over a population of examinees. Just as score reliability varies across individuals and subgroups, one can expect that the reliability of score profiles will vary across examinees. This article proposes two conditional indices of score profile utility grounded in multivariate generalizability theory. The first is based on the ratio of observed profile variance to the profile variance that can be attributed to random error. The second quantifies the proportion of observed variability in a score profile that can be attributed to true score profile variance. The article describes the indices, illustrates their use with two empirical examples, and evaluates their properties with simulated data. The results suggest that the proposed estimators of profile error variance are consistent with the known error in simulated score profiles and that they provide information beyond that provided by traditional measures of subscore utility. The simulation study suggests that artificially large values of the indices could occur for about 5% to 8% of examinees. The article concludes by suggesting possible applications of the indices and discusses avenues for further research.
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Czaplewski, Raymond L., et David Bruce. « Retransformation bias in a stem profile model ». Canadian Journal of Forest Research 20, no 10 (1 octobre 1990) : 1623–30. http://dx.doi.org/10.1139/x90-215.
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An unbiased profile model, fit to diameter divided by diameter at breast height, overestimated volume of 5.3-m log sections by 0.5 to 3.5%. Another unbiased profile model, fit to squared diameter divided by squared diameter at breast height, underestimated bole diameters by 0.2 to 2.1%. These biases are caused by retransformation of the predicted dependent variable; the degree of retransformation bias depends upon choice of dependent variable in the regression model, variance of its prediction errors, and the bole position of the desired prediction. Retransformation biases were greatest near the merchantable top of large trees. Equations are given that reduce the magnitude of these biases, but accurate variance models are required. Additional biases are identified for more complex transformations of stem profile models.
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Ida, T., S. Shimazaki, H. Hibino et H. Toraya. « Diffraction peak profiles from spherical crystallites with lognormal size distribution ». Journal of Applied Crystallography 36, no 5 (8 septembre 2003) : 1107–15. http://dx.doi.org/10.1107/s0021889803011580.
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An efficient and accurate method to evaluate the theoretical diffraction peak profiles from spherical crystallites with lognormal size distribution (SLN profile) is presented. Precise results can be obtained typically by an eight-term numerical integral for any values of the parameters, by applying an appropriate substitution of the variable to the integral formula. The calculated SLN profiles have been verified by comparison with those calculated by inverse Fourier transform from the exact analytical solution of the Fourier-transformed SLN profile. It has been found that the shape of the SLN profile strongly depends on the variance of size distribution. When the logarithmic standard deviation ω of the size distribution is close to 0.76, the SLN profile becomes close to a Lorentzian profile, and `super-Lorentzian' profiles are predicted for larger values of ω, as has been concluded by Popa & Balzar [J. Appl. Cryst.(2002),35, 338–346]. The intrinsic diffraction peak profiles of an SiC powder sample obtained by deconvolution of the instrumental function have certainly shown `super-Lorentzian' line profiles, and they are well reproduced by the SLN profile for the value ω = 0.93.
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Hays, J. Ray. « WAIS-R Profile Variability of Psychiatric Inpatients ». Psychological Reports 79, no 3_suppl (décembre 1996) : 1154. http://dx.doi.org/10.2466/pr0.1996.79.3f.1154.
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Sparks, Joshua, Srinivasan Balaji et Hosam Mahmoud. « The containment profile of hyper-recursive trees ». Journal of Applied Probability 59, no 1 (17 janvier 2022) : 278–96. http://dx.doi.org/10.1017/jpr.2021.50.
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AbstractWe investigate vertex levels of containment in a random hypergraph grown in the spirit of a recursive tree. We consider a local profile tracking the evolution of the containment of a particular vertex over time, and a global profile concerned with counts of the number of vertices of a particular containment level.For the local containment profile, we obtain the exact mean, variance, and probability distribution in terms of standard combinatorial quantities such as generalized harmonic numbers and Stirling numbers of the first kind. Asymptotically, we observe phases: the early vertices have an asymptotically normal distribution, intermediate vertices have a Poisson distribution, and late vertices have a degenerate distribution.As for the global containment profile, we establish an asymptotically normal distribution for the number of vertices at the smallest containment level as well as their covariances with the number of vertices at the second smallest containment level and the variances of these numbers. The orders in the variance–covariance matrix establish concentration laws.
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Hays, J. Ray, et J. Bryant Shaw. « Wasi Profile Variability in a Sample of Psychiatric Inpatients ». Psychological Reports 92, no 1 (février 2003) : 164–66. http://dx.doi.org/10.2466/pr0.2003.92.1.164.
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This study examined the variability of Wechsler Abbreviated Scale of Intelligence profiles using the subtest range and profile variability index in a sample of 70 psychiatric inpatients. The subtest range and profile variability index were correlated .93 ( p < .001), indicating that either measure may be used to assess profile variance. Comparison of profile variability on this abbreviated scale with other Wechsler intelligence scales in similar populations suggests that variability measures are not comparable across the tests.
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Rahmah Humaeroh, Muhammad Nur Aidi, Bagus Sartono et Nazarina. « Analysis of Multivariate Data Variance Detected Outlier to Determine Factors Influencing Lipid Profile in Diabetes Patients ». International Journal of Scientific Research in Science, Engineering and Technology 11, no 2 (30 mars 2024) : 147–54. http://dx.doi.org/10.32628/ijsrset2411213.
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Diabetes is characterized by high blood glucose levels and can lead to cardiovascular complications. This research, will be investigating he factors influencing lipid profile in diabetes patients and the differences in these profiles under various treatments. The research used the MANOVA test to analyze differences in lipid profile under different treatment and controlled for covariates using Mancova. They also used robust methods to address outliers is minimum covariance determinant. The result suggest that gender is a significant factor influencing lipid profile in diabetes patients. The most effective analytical methods were found to be robust manova and robust mancova, with low RMSE values indicating their accuracy.
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Houison, Ronald J., Andrea Lamont-Mills, Michael Kotiw et Peter C. Terry. « Strike 3 … Out ! Investigating Pre-Game Moods, Performance, and Mental Health of Softball Umpires ». Sports 12, no 2 (2 février 2024) : 50. http://dx.doi.org/10.3390/sports12020050.
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Mood research in sports typically focuses on athletes, with sports officials being largely overlooked. In the current study, mood profiling was used to determine if softball umpires reported an identifiable and consistent mood profile and if mood was predictive of umpiring performance and/or reflective of positive mental health. Eleven male and five female participants aged 25–68 years (M = 48.5 ± 15.5 years) each completed the Brunel Mood Scale on multiple occasions prior to officiating games at the 2020 U18 National Softball Championships. A total of 185 mood profiles were analysed. Performance was assessed using Softball Australia’s official umpire assessment tool. Overall, participants reported an iceberg mood profile, which tends to be associated with positive mental health and good performance. Umpiring performances (pass/fail) were correctly classified in 75.0% of cases from tension, depression, and confusion scores (p = 0.003). Participant sex explained 25.7% of the variance in mood scores (p < 0.001); age, 25.8% of the variance (p < 0.001); position on the diamond, 10.5% of the variance (p = 0.003); and accreditation level, 14.3% of the variance (p < 0.001). Australian softball umpires typically reported mood profiles associated with positive mental health, and none reported profiles associated with risk of mental ill-health.
Thèses sur le sujet "Variance profile"
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Vaníček, Jakub. « Měření relativní variance optické intenzity ». Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-219091.
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The intention of this master‘s thesis is the measurment of relative variance of optical intensity. In the first place, I have been studied Kolmogorov cascade theory of turbulence and relative variance of optical intensity . In addition, I have been deal with turbulent cells, Gaussian beam, Top Hat beam and influence of the atmospheric turbulences on the intensity profile of the laser beam. Lastly I have been measured determine influence of the atmospheric turbulences on the intensity profile of the laser beam and I have been calculated relative variance of optical intensity. I have suggested the optimum beam profile in the turbulent atmosphere from acquired data.
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Zhang, Yue. « Detection copy number variants profile by multiple constrained optimization ». HKBU Institutional Repository, 2017. https://repository.hkbu.edu.hk/etd_oa/439.
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Copy number variation, causing by the genome rearrangement, generally refers to the copy numbers increased or decreased of large genome segments whose lengths are more than 1kb. Such copy number variations mainly appeared as the sub-microscopic level of deletion and duplication. Copy number variation is an important component of genome structural variation, and is one of pathogenic factors of human diseases. Next generation sequencing technology is a popular CNV detection method and it has been widely used in various fields of life science research. It possesses the advantages of high throughput and low cost. By tailoring NGS technology, it is plausible to sequence individual cells. Such single cell sequencing can reveal the gene expression status and genomic variation profile of a single-cell. Single cell sequencing is promising in the study of tumor, developmental biology, neuroscience and other fields. However, there are two challenging problems encountered in CNV detection for NGS data. The first one is that since single-cell sequencing requires a special genome amplification step to accumulate enough samples, a large number of bias is introduced, making the calling of copy number variants rather challenging. The performances of many popular copy number calling methods, designed for bulk sequencings, are not consistent and cannot be applied on single-cell sequenced data directly. The second one is to simultaneously analyze genome data for multiple samples, thus achieving assembling and subgrouping similar cells accurately and efficiently. The high level of noises in single-cell-sequencing data negatively affects the reliability of sequence reads and leads to inaccurate patterns of variations. To handle the problem of reliably finding CNVs in NGS data, in this thesis, we firstly establish a workflow for analyzing NGS and single-cell sequencing data. The CNVs identification is formulated as a quadratic optimization problem with both constraints of sparsity and smoothness. Tailored from alternating direction minimization (ADM) framework, an efficient numerical solution is designed accordingly. The proposed model was tested extensively to demonstrate its superior performances. It is shown that the proposed approach can successfully reconstruct CNVs especially somatic copy number alteration patterns from raw data. By comparing with existing counterparts, it achieved superior or comparable performances in detection of the CNVs. To tackle this issue of recovering the hidden blocks within multiple single-cell DNA-sequencing samples, we present an permutation based model to rearrange the samples such that similar ones are positioned adjacently. The permutation is guided by the total variational (TV) norm of the recovered copy number profiles, and is continued until the TV-norm is minimized when similar samples are stacked together to reveal block patterns. Accordingly, an efficient numerical scheme for finding this permutation is designed, tailored from the alternating direction method of multipliers. Application of this method to both simulated and real data demonstrates its ability to recover the hidden structures of single-cell DNA sequences.
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Abrhám, Ondřej. « Odhad měsíčních odchylek závodových nákladů dle nákladových skupin - analýza postupu a návrh zlepšení ». Master's thesis, Vysoká škola ekonomická v Praze, 2008. http://www.nusl.cz/ntk/nusl-5252.
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Theory: - Controlling - its function and structure - Costs Analytical part: - Cost variance tracking and evaluation of its monthly prediction - Proposal of best practices for cost variance prediction done on monthly basis
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Oliveira, Madalena Mendes de Almeida Esteves de. « On Robo assessment of risk profiles ». Master's thesis, Instituto Superior de Economia e Gestão, 2020. http://hdl.handle.net/10400.5/20778.
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Mestrado em FinançasNos tempos que correm, o mundo tecnológico tem crescido a um ritmo muito acelerado, o que significa que tem de haver uma rápida adaptação, e as empresas sentem a necessidade de se reinventar. As inovações tecnológicas também alcançaram a indústria de serviços de gestão de ativos com os chamados Robo-Advisors. Estas são as plataformas que fornecem aconselhamento financeiro ou gestão automatizada de investimentos. Os Robo-Advisors coletam informações sobre a situação financeira e os objetivos futuros de seus clientes através de questionários, recomendando carteiras baseadas em ETFs, supostamente adequadas ao perfil de risco do investidor. No entanto, os questionários parecem vagos e os robôs não revelam os métodos usados na alocação de ativos. Este estudo visa contribuir para a compreensão da eficácia dessas plataformas. Baseia-se na teoria da utilidade esperada e, para vários níveis de aversão relativa ao risco, propomos carteiras de média-variância ótimas. Em seguida, comparamos as nossas carteiras com as carteiras propostas pela plataforma Riskalyze, para três tipos diferentes de investidores: conservador, moderado e agressivo. Avaliando o seu desempenho in-sample e out-of-sample. Concluímos que, a longo prazo, a metodologia utilizada pelos robo-portfolios, de acordo com o perfil de risco do investidor, pode ser eficaz para investidores que apresentam um maior nível de aversão ao risco, porém para investidores com aversão ao risco relativamente menor os portfólios de média-variância tendem a ter melhor desempenho.
Nowadays, the technological world has been growing at a very fast rate, which means there has to be a quick adaptation and companies feel the need to reinvent themselves. Technological innovations also reached the asset management service industry with the so-called the Robo-Advisors. These are platforms that provide financial advice or automated investment management. Robo-Advisors collect information about their clients' financial situation and future goals through questionnaires, then recommending ETF based portfolios supposed to fit investor's risk profile. However, questionnaires seem to be vague, and robos do not reveal the methods used in asset allocation. This study aims at contributing to the understanding the effectiveness of these platforms. It relies on expected utility theory, and, for various levels of relative risk aversion we propose optimal mean-variance portfolios. We then compare our portfolios with the portfolios proposed by the Riskalyze platform, for three different types of investors: conservative, moderate and aggressive. By evaluating their in-sample and out-of-sample performance. We conclude, that in the long run, the methodology used by robo-portfolios, according to the investor's risk profile, can be effective for investors who have a higher level of risk aversion, however for investors with relatively lower risk aversion the mean-variance portfolios tend to perform better.
info:eu-repo/semantics/publishedVersion
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Wilson, Benton Wade. « Modeling of performance behavior in gas condensate reservoirs using a variable mobility concept ». Texas A&M University, 2003. http://hdl.handle.net/1969.1/317.
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The proposed work provides a concept for predicting well performance behavior in a gas condensate reservoir using an empirical model for gas mobility. The proposed model predicts the behavior of the gas permeability (or mobility) function in the reservoir as condensate evolves and the gas permeability is reduced in the near-well region due to the "condensate bank". The proposed model is based on observations of simulated reservoir performance and predicts the behavior of the gas permeability over time and radial distance. This model is given by:
The proposed concept has potential applications in the development of a pressure-time-radius solution for gas condensate reservoirs experiencing this type of mobility behavior. We recognize that the proposed concept (i.e., a radially-varying gas permeability) is oversimplified, in particular, it ignores the diffusive effects of the condensate (i.e., the viscosity-compressibility behavior). However, we have effectively validated the proposed model using literature results derived from numerical simulation.
This new solution is presented graphically in the form of "type curves." We propose that the "time" form of this solution be used for applications in well test analysis. Previous developments used for the analysis of well test data from gas condensate reservoirs consider the radial composite reservoir model, which utilizes a "step change" in permeability at some radial distance away from the wellbore. Using our proposed solution we can visualize the effect of the varying gas permeability in time and radius (a suite of (dimensionless) radius and time format plots are provided). In short, we can visualize the evolution of the condensate zone as it evolves in time and radial distance.
A limitation is the simplified form of the kg profile as a function of radius and time - as well as the dependence/appropriateness of the α-parameter. While we suspect that the α-parameter represents the influence of both fluid and rock properties, we do not examine how such properties can be used to calculate the α-parameter.
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Dabo, Issa-Mbenard. « Applications de la théorie des matrices aléatoires en grandes dimensions et des probabilités libres en apprentissage statistique par réseaux de neurones ». Electronic Thesis or Diss., Bordeaux, 2025. http://www.theses.fr/2025BORD0021.
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Le fonctionnement des algorithmes d’apprentissage automatique repose grandement sur la structure des données qu’ils doivent utiliser. La majorité des travaux de recherche en apprentissage automatique se concentre sur l’étude de données homogènes, souvent modélisées par des variables aléatoires indépendantes et identiquement distribuées. Pourtant, les données apparaissant en pratique sont souvent hétérogènes. Nous proposons dans cette thèse de considérer des données hétérogènes en les dotant d’un profil de variance. Cette notion, issue de la théorie des matrices aléatoires, nous permet notamment d’étudier des données issues de modèles de mélanges. Nous nous intéressons plus particulièrement à la problématique de la régression ridge à travers deux modèles : la régression ridge linéaire (linear ridge model) et la régression ridge à caractéristiques aléatoires (random feature ridge model). Nous étudions dans cette thèse la performance de ces deux modèles dans le cadre de la grande dimension, c’est-à-dire lorsque la taille de l’échantillon d’entraînement et la dimension des données tendent vers l’infini avec des vitesses comparables. Dans cet objectif, nous proposons des équivalents asymptotiques de l’erreur d’entraînement et de l’erreur de test relatives aux modèles d’intérêt. L’obtention de ces équivalents repose grandement sur l’étude spectrale issue de la théorie des matrices aléatoires, des probabilités libres et de la théorie des trafics. En effet, la mesure de la performance de nombreux modèles d’apprentissage dépend de la distribution des valeurs propres de matrices aléatoires. De plus, ces résultats nous ont permis d’observer des phénomènes spécifiques à la grande dimension, comme le phénomène de la double descente. Notre étude théorique s’accompagne d’expériences numériques illustrant la précision des équivalents asymptotiques que nous fournissonsThe functioning of machine learning algorithms relies heavily on the structure of the data they are given to study. Most research work in machine learning focuses on the study of homogeneous data, often modeled by independent and identically distributed random variables. However, data encountered in practice are often heterogeneous. In this thesis, we propose to consider heterogeneous data by endowing them with a variance profile. This notion, derived from random matrix theory, allows us in particular to study data arising from mixture models. We are particularly interested in the problem of ridge regression through two models: the linear ridge model and the random feature ridge model. In this thesis, we study the performance of these two models in the high-dimensional regime, i.e., when the size of the training sample and the dimension of the data tend to infinity at comparable rates. To this end, we propose asymptotic equivalents for the training error and the test error associated with the models of interest. The derivation of these equivalents relies heavily on spectral analysis from random matrix theory, free probability theory, and traffic theory. Indeed, the performance measurement of many learning models depends on the distribution of the eigenvalues of random matrices. Moreover, these results enabled us to observe phenomena specific to the high-dimensional regime, such as the double descent phenomenon. Our theoretical study is accompanied by numerical experiments illustrating the accuracy of the asymptotic equivalents we provide
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Hillwig, Todd C. « Analysis of the radial profile emissivity of accretion disks in cataclysmic variables ». Virtual Press, 1995. http://liblink.bsu.edu/uhtbin/catkey/941346.
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HAUDOT, STEPHANE. « Contribution a l'etude des caracteristiques aerodynamiques d'un profil a polaire variable ». Aix-Marseille 2, 1995. http://www.theses.fr/1995AIX22067.
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Dans le cadre d'une approche numerique, cette etude presente les caracteristiques aerodynamiques et geometriques d'un profil d'aile susceptible de se deformer en fonction du champ de vitesse infinie amont ; l'objectif final etant d'induire des variations significatives de portance et de trainee. La configuration retenue est constituee d'un profil naca traverse par un canal horizontal (deux elements). L'etude est realisee a partir du code de calcul en mecanique des fluides phoenics (methode des volumes finis et schema hybrid) et dans le cadre d'un ecoulement turbulent (modele k-e). Plusieurs types de deplacements sont consideres: une reduction ou une augmentation de la section du canal et une rotation de l'un des elements. Les resultats obtenus revelent que seul un mouvement de rotation conduit a des variations significatives de portance et de trainee: dans l'intervalle considere, une reduction de dix pourcents est obtenue pour le cx et le cz. Une etude experimentale devant etre realisee ulterieurement, une simulation numerique de l'ensemble veine d'essais profil complet a egalement ete realisee ; l'objectif etait d'optimiser la geometrie de l'ensemble veine d'essais profil complet afin de conserver qualitativement les performances aerodynamiques du profil en milieu non-confine
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Lee, Joongsup. « New control charts for monitoring univariate autocorrelated processes and high-dimensional profiles ». Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42711.
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In this thesis, we first investigate the use of automated variance estimators in distribution-free statistical process control (SPC) charts for univariate autocorrelated processes. We introduce two variance estimators---the standardized time series overlapping area estimator and the so-called quick-and-dirty autoregressive estimator---that can be obtained from a training data set and used effectively with distribution-free SPC charts when those charts are applied to processes exhibiting nonnormal responses or correlation between successive responses. In particular, we incorporate the two estimators into DFTC-VE, a new
distribution-free tabular CUSUM chart developed for autocorrelated processes; and we compare its performance with other state-of-the-art distribution-free SPC charts. Using either of the two variance estimators, the DFTC-VE outperforms its competitors in terms of both in-control and
out-of-control average run lengths when all the competing procedures are tested on the same set of independently sampled realizations of selected
autocorrelated processes with normal or nonnormal noise components.
Next, we develop WDFTC, a wavelet-based distribution-free CUSUM chart for detecting shifts in the mean of a high-dimensional profile with noisy components that may exhibit nonnormality, variance heterogeneity, or correlation between profile components. A profile describes the relationship between a selected quality characteristic and an input (design) variable over the experimental region. Exploiting a discrete wavelet transform (DWT) of the mean in-control profile, WDFTC selects a reduced-dimension vector of the associated DWT components from which the mean in-control profile can be
approximated with minimal weighted relative reconstruction error. Based on randomly sampled Phase I (in-control) profiles, the covariance matrix of the corresponding reduced-dimension DWT vectors is estimated using a matrix-regularization method; then the DWT vectors are aggregated (batched) so that the nonoverlapping batch means of the reduced-dimension DWT vectors
have manageable covariances. To monitor shifts in the mean profile during Phase II operation, WDFTC computes a Hotelling's T-square--type statistic from successive nonoverlapping batch means and applies a CUSUM procedure to those statistics, where the associated control limits are evaluated
analytically from the Phase I data. We compare WDFTC with other state-of-the-art profile-monitoring charts using both normal and nonnormal
noise components having homogeneous or heterogenous variances as well as independent or correlated components; and we show that WDFTC performs well, especially for local shifts of small to medium size, in terms of both in-control and out-of-control average run lengths.
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Encarnação, Rui Jorge Junqueiro. « Análise do perfil de ácidos gordos de camarinha, Palaemonetes varians ». Master's thesis, ISA, 2013. http://hdl.handle.net/10400.5/6122.
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Mestrado em Engenharia Zootécnica - Produção Animal - Instituto Superior de Agronomia / Faculdade de Medicina VeterináriaOne of the benefits associated with the consumption of fishery products is their fatty acid composition. In this dissertation we analyze the fatty acids profile of Atlantic ditch shrimp Palaemonetes varians, determined by gas chromatography. For this, 16 samples were collected in the Sado estuary area and examined. This study identified the majority of the P. varians fatty acids. In terms of highest quantity, we had the palmitic acid in SFA group, the oleic acid in MUFA and finally EPA in PUFA. Higher n-3/n-6 and PUFA/SFA ratios were also noticed. Related outcomes were found in studies associated to several other species of crustaceans. In July, the P. varians exhibited lower levels of MUFA, higher SFA values and higher n-3/n-6 ratio in comparison with the values registered in November (p<0,001). Comparing adult and juvenile P. varians, and despite not having significant variations in PUFA, it is noted the higher concentration of MUFA and lower SFA in adults (p<0,05). Few significant differences were observed between wild and not wild P. varians. A higher concentration of palmitic acid was found in not wild P. varians.These differences may be explained mainly by the food ingested by P. varians.
Livres sur le sujet "Variance profile"
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Fraser, D. A. S. Adjustments to profile likelihood. Toronto : University of Toronto, Dept. of Statistics, 1988.
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Engle, R. F. Valuation of variance forecasts with simulated option markets. Cambridge, MA : National Bureau of Economic Research, 1990.
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(Firm), Elsevier Advanced Technology, dir. Profile of the European motors and drives industry : Market forecasts to 1999. Oxford : Elsevier Advanced Technology, 1994.
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Raskalinos, Valeriya. Pedagogical skills. ru : INFRA-M Academic Publishing LLC., 2024. http://dx.doi.org/10.12737/1865677.
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The educational manual presents educational materials on the general professional discipline “Pedagogical Excellence” (a variable part of the training program for mid-level specialists). Aimed at developing students' professional individuality through the integration of experience, theoretical knowledge and practical skills. Meets the requirements of the latest generation of federal state educational standards for secondary education. For students of secondary specialized educational institutions with a pedagogical profile, as well as teachers of pedagogical colleges working with students studying in the specialty “Preschool Education”.
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Shishkin, Andrey. Introduction to the axiomatic theory of elementary functions. ru : INFRA-M Academic Publishing LLC., 2021. http://dx.doi.org/10.12737/1209581.
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Contains an exposition of the basic concepts and theorems of the axiomatic theory of the basic elementary functions of real and complex variables. The textbook is written on the basis of lectures given by the author for a number of years at the Armavir State Pedagogical University, at the Slavyansk-on-Kuban State Pedagogical Institute and at the branch of the Kuban State University in Slavyansk-on-Kuban. It is intended for students of natural-mathematical profiles of preparation of the direction "Pedagogical education". It can be used in the study of mathematical analysis, the theory of functions of a real variable, the theory of functions of a complex variable, etc.
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Kuz'mina, Tat'yana. Self-awareness and personal adaptive potential in normal and impaired development. ru : INFRA-M Academic Publishing LLC., 2021. http://dx.doi.org/10.12737/1086621.
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The monograph presents the generalized results of the author's scientific activity related to the diagnosis and phenomenological description of the state of self-consciousness and the Self-concept of persons with developmental disorders, in particular with mild mental retardation. The variants of self-awareness diagnostics and a comprehensive assessment of the personal adaptive potential of subjects of different ages with intellectual disabilities are presented and methodologically justified. The presented methods allow us to form an individual adaptive profile based on a quantitative assessment of qualitative indicators of adaptability/maladaptivity. The content aspects of the formation of the antisocial potential of a person with mild mental retardation, in particular, the problems of suggestibility, indoctrination and the participation of persons with intellectual disabilities in criminal communities, are separately identified.
It will be useful for students, postgraduates, researchers and practitioners in the field of pedagogy, psychology, law.
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Lemeshko, Boris, et Irina Veretel'nikova. Criteria for testing hypotheses about randomness and the absence of a trend. Application Guide. ru : INFRA-M Academic Publishing LLC., 2021. http://dx.doi.org/10.12737/1587437.
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The monograph discusses the application of statistical criteria aimed at testing hypotheses about the absence of a trend in the analyzed samples. The rejection of such a hypothesis gives grounds to consider the analyzed data as samples of independent equally distributed random variables. We consider a set of special criteria aimed at testing such hypotheses, as well as a set of criteria for the uniformity of laws, the uniformity of averages and the uniformity of variances, which can also be used for these purposes. The disadvantages and advantages of various criteria are emphasized, the application of criteria in conditions of violation of standard assumptions is considered. Estimates of the power of the criteria are given, which allows you to navigate when choosing the most preferred criteria. Following the recommendations will ensure the correctness and increase the validity of statistical conclusions when analyzing data.
It is intended for specialists who are interested in the application of statistical methods for the analysis of various aspects and trends of the surrounding reality and who are in contact with the processing of experimental results, the need for data analysis in their activities. It will be useful for engineers, researchers, specialists of various profiles (doctors, biologists, sociologists, economists, etc.) who face the need for statistical analysis of experimental results in their activities. It will also be useful for university teachers, graduate students and students.
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Barr, Ronny. Ronny Bar Profiles - Spitfire the Merlin Variants. Mortons Media Group, 2024.
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Cheng, Russell. Standard Asymptotic Theory. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198505044.003.0003.
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This book relies on maximum likelihood (ML) estimation of parameters. Asymptotic theory assumes regularity conditions hold when the ML estimator is consistent. Typically an additional third derivative condition is assumed to ensure that the ML estimator is also asymptotically normally distributed. Standard asymptotic results that then hold are summarized in this chapter; for example, the asymptotic variance of the ML estimator is then given by the Fisher information formula, and the log-likelihood ratio, the Wald and the score statistics for testing the statistical significance of parameter estimates are all asymptotically equivalent. Also, the useful profile log-likelihood then behaves exactly as a standard log-likelihood only in a parameter space of just one dimension. Further, the model can be reparametrized to make it locally orthogonal in the neighbourhood of the true parameter value. The large exponential family of models is briefly reviewed where a unified set of regular conditions can be obtained.
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Griehl, Manfred. Siebel Fh 104/Si 204 : And License Variants (Luftwaffe Profile Series , No 11). Schiffer Publishing, 1998.
Trouver le texte intégralChapitres de livres sur le sujet "Variance profile"
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Stamm, Aymeric, Jolene Singh, Onur Afacan et Simon K. Warfield. « Analytic Quantification of Bias and Variance of Coil Sensitivity Profile Estimators for Improved Image Reconstruction in MRI ». Dans Lecture Notes in Computer Science, 684–91. Cham : Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-24571-3_82.
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Osaki, Yoji. « Nonradial Modes in Line-Profile Variable Stars ». Dans Seismology of the Sun and the Distant Stars, 453–63. Dordrecht : Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4608-8_47.
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van Ruitenbeek, Floris, Boi Okken et Wesley Roozing. « Variable Stiffness Mechanism Using a Cam Profile ». Dans Springer Proceedings in Advanced Robotics, 76–80. Cham : Springer Nature Switzerland, 2024. https://doi.org/10.1007/978-3-031-76424-0_14.
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Silva-Corvalán, Carmen. « The social profile of a syntactico-semantic variable ». Dans Diversity and Diachrony, 279. Amsterdam : John Benjamins Publishing Company, 1986. http://dx.doi.org/10.1075/cilt.53.24sil.
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Mathai, Arak M., Serge B. Provost et Hans J. Haubold. « Profile Analysis and Growth Curves ». Dans Multivariate Statistical Analysis in the Real and Complex Domains, 813–44. Cham : Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-95864-0_14.
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AbstractWe will utilize the same notations as in the previous chapters. Lower-case letters x, y, … will denote real scalar variables, whether mathematical or random. Capital letters X, Y, … will be used to denote real matrix-variate mathematical or random variables, whether square or rectangular matrices are involved. A tilde will be placed on top of letters such as $$\tilde {x},\tilde {y},\tilde {X},\tilde {Y}$$ x ~ , y ~ , X ~ , Y ~ to denote variables in the complex domain. Constant matrices will for instance be denoted by A, B, C. A tilde will not be used on constant matrices unless the point is to be stressed that the matrix is in the complex domain.
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Zerbi, Filippo M. « Simultaneous Light Curve, Color Curve and Line Profile Fitting for Pulsating Stars ». Dans Variable Stars as Essential Astrophysical Tools, 293–312. Dordrecht : Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-011-4299-1_11.
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Tribedi, Apurba. « Variable Modulus of Subgrade Reaction - Settlement Profile Convergence Method ». Dans Advanced Research on Shallow Foundations, 162–84. Cham : Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-01923-5_13.
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Richter, Michael, et Ariel Rubinstein. « 2. The Permissible and the Forbidden ». Dans No Prices No Games !, 37–64. 2e éd. Cambridge, UK : Open Book Publishers, 2024. http://dx.doi.org/10.11647/obp.0438.02.
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Following Richter and Rubinstein (2020), we analyze an equilibrium concept based upon social norms: the Y-equilibrium. A Y-equilibrium is a set of permissible alternatives and a profile of choices, one for each agent, such that: (i) each agent's choice is optimal from among the permissible alternatives; (ii) the profile of choices is feasible; and (iii) the set of permissible alternatives is maximal in the sense that there is no superset of permissible alternatives from which a profile satisfying (i) and (ii) can be found. By this definition, two forces make a permissible set unstable: The first modifies the permissible set in the case that the profile of (intended) choices is not feasible, while the second loosens restrictions on the permissible set as long as a new profile of optimal choices is feasible. We also consider a variant of this concept where we require that the permissible set is convex. We study the Y-equilibria of a variety of examples and prove existence theorems, “welfare” theorems and a structure theorem when the set of alternatives is Euclidean.
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Richter, Michael, et Ariel Rubinstein. « 2. The Permissible and the Forbidden ». Dans No Prices No Games !, 37–64. Cambridge, UK : Open Book Publishers, 2024. http://dx.doi.org/10.11647/obp.0404.02.
Texte intégralRésumé :
Following Richter and Rubinstein (2020), we analyze an equilibrium concept based upon social norms: the Y-equilibrium. A Y-equilibrium is a set of permissible alternatives and a profile of choices, one for each agent, such that: (i) each agent's choice is optimal from among the permissible alternatives; (ii) the profile of choices is feasible; and (iii) the set of permissible alternatives is maximal in the sense that there is no superset of permissible alternatives from which a profile satisfying (i) and (ii) can be found. By this definition, two forces make a permissible set unstable: The first modifies the permissible set in the case that the profile of (intended) choices is not feasible, while the second loosens restrictions on the permissible set as long as a new profile of optimal choices is feasible. We also consider a variant of this concept where we require that the permissible set is convex. We study the Y-equilibria of a variety of examples and prove existence theorems, “welfare” theorems and a structure theorem when the set of alternatives is Euclidean.
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Wu, Hanji, Yongsheng Xu et Zhen Zhong. « Single-Profile Choice Functions and Variable Societies : Characterizing Approval Voting ». Dans Studies in Choice and Welfare, 143–48. Berlin, Heidelberg : Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-46439-7_9.
Texte intégralActes de conférences sur le sujet "Variance profile"
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Dordova, Lucie, et Otakar Wilfert. « Distribution of optical intensity relative variance in laser beam profile ». Dans 2010 15th Conference on Microwave Techniques (COMITE 2010). IEEE, 2010. http://dx.doi.org/10.1109/comite.2010.5481540.
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Rejivas, V. A., A. Praveen et T. Ajitha. « Determination of Collinearity Developed in the CMB Model with the Concepts of Multi Linear Regression Analysis ». Dans 2nd International Conference on Modern Trends in Engineering Technology and Management. AIJR Publisher, 2023. http://dx.doi.org/10.21467/proceedings.160.12.
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The Chemical Mass Balance model (CMB) gives an accurate source apportionment for the contribution of the sources with the input data of the source profile and receptor data collected. The source profiles for different sources should have a unique and specific species characterization for getting accurate source apportionment results. But due to the mixing of sources, the species characterization source profile may not have unique and specific species characterization due to the non-availability of the exact representation of particular sources and culminates collinearity of species during the CMB analysis. It leads to negative source apportionment results in the CMB analysis. Multi Linear Regression analysis that addresses in the study can effectively be used to identify the collinearity contributing sources. The Multi Linear Regression parameters such as tolerance, variance inflation factor (VIF), condition index, and variance decomposition proportions developed with the source profile variables (source profiles for soil, paved road dust, biomass, and traffic) are used for identifying the collinear sources. The tolerance value for the soil and paved road dust sources are obtained as 0.001 each and the variance inflation factor (VIF) for both are obtained as 204.2 and 208.8 respectively. It indicates the collinearity between soil and paved road dust. Collinearity diagnostics of the regression equations showed that the condition index and the variance decomposition proportion obtained for the soil and paved road dust were greater than 30 (104.09) and 90% (100%) respectively. Therefore, the presence of strong collinearity between soil and paved road dust can be understood.
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Jeans, Gus, Liam Harrington-Missin, Andrew Watson et Jon Upton. « The Use of Empirical Orthogonal Functions for Deriving Response Based Extreme Current Profiles ». Dans ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-83052.
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Coherent extreme current profiles are derived to reduce the over-conservatism associated with the traditional assumption that extreme currents occur at all depths through the water column simultaneously. Empirical Orthogonal Function (EOF) analysis has proven effective for derivation of coherent extreme current profiles in regions where it effectively captures the dominant characteristics of the flow regime. This is despite the questionable suitability of EOF for Current Profile Characterisation, which reduces a large current profile data set into a much smaller set of profiles for riser fatigue studies. EOF Mode 1 and 2 are used to represent six years of in-situ current profiles accounting for 97.75% of the original variance. With the assumption that depth integrated speed squared is proportional to drag on a simple riser, three sets of extreme current profiles were derived. A) Profiles associated with extreme near surface current speeds, B) Profiles associated with extreme mid-depth current speeds and C) Profiles associated with extreme drag on a riser.
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Prots, Andriy, Lukas Schlüter, Matthias Voigt, Marcus Meyer et Ronald Mailach. « Sensitivity Analysis of Performance Parameters of a Compressor Blade With Correlated Profile Parameters ». Dans ASME Turbo Expo 2023 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/gt2023-102442.
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Abstract Sensitivity analysis is a commonly used method in engineering applications to identify the input variables whose variance has the largest impact on the variance of a model output. Two major difficulties are often encountered. First, many computationally intensive model evaluations are required to obtain sensitivity indices with high statistical confidence. Second, input variables are often correlated, which cannot be handled unambiguously by most sensitivity analysis methods. Shapley values are a promising sensitivity measure for problems with correlations between input variables, as interaction effects are distributed evenly among the respective input parameters. However, Shapley values are affected by spurious correlations with input variables that have no functional influence. In this case, the Shapley value is dispersed and its significance is reduced. Therefore, a sensitivity measure that detects input variables without functional influence is desirable. This paper analyzes the behavior of different sensitivity measures with respect to correlated input variables. It is shown that first-order and total-effect Sobol sensitivity indices, and Shapley values alone do not fully detect input variables without functional influence. Therefore, the modified coefficient of importance is introduced to detect such input variables. In the final part of this paper, a sensitivity analysis for a compressor blade subject to manufacturing variability and wear is performed using the aforementioned sensitivity measures. The blade variation is described by profile parameters. First, the sensitivity analysis is performed, which allows to identify profile parameters that have no functional influence on the isentropic efficiency. Then, the sensitivity analysis is repeated with appropriately grouped profile parameters. It is found that the profile parameters describing the blade thickness have the greatest influence on the variance of the efficiency. With the proposed approach, it is therefore possible to identify the most important profile parameters, even if they are correlated.
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Sundaresan, S., K. Ishii et D. R. Houser. « A Procedure Using Manufacturing Variance to Design Gears With Minimum Transmission Error ». Dans ASME 1989 Design Technical Conferences. American Society of Mechanical Engineers, 1989. http://dx.doi.org/10.1115/detc1989-0084.
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Abstract This paper deals with the design of spur gears that have minimum transmission error and are insensitive to manufacturing variance. We address two stages of design: 1) generation of candidate designs (selection of number of teeth, pressure angle, etc.), and 2) tooth profile modification. The first stage involves a search of discrete combinations of design variables, while the second stage utilizes numerical optimization techniques. The key research issue is finding a candidate design and its profile modification that not only has low transmission error, but is insensitive to variations in the design values caused by the manufacturing process. To achieve this goal, the procedure applies Taguchi’s concept of parameter design. In this paper, we consider a design problem with a set specification: fixed center distance, speed ratio, and transmission torque. We seek to find a limited number of candidate designs by applying conventional design generation techniques and some design heuristics. For each candidate design, the procedure determines the optimum profile modification (linear tip relief) by linking the Load Distribution Program (LDP) for gears with an optimization program package (OPTPAK). From the resulting peak optimum, we further seek the statistical optimum using an algorithm developed in this paper. The statistical optimum shows a nominal increase in the transmission error, but is quite insensitive to typical process error associated with gear manufacturing. The developed algorithm readily applies to other gear designs as well as other types of machine elements. In particular, we foresee our procedure to be particularly effective for helical gears. We hope to further our method by developing a means to add statistical heuristics to the discrete design generation stage.
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Suzuki, Hiroki, Kouji Nagata, Yasuhiko Sakai et Ryota Ukai. « An Experimental Study on Turbulent Mixing of High-Schmidt-Number Scalar in Grid Turbulence by Means of PIV and PLIF ». Dans ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-21013.
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Turbulent mixing of high-Schmidt-number passive scalar in shear-free grid turbulence is experimentally investigated using a water channel. The Reynolds number based on the mesh size of the grid and cross-sectionally averaged mean velocity is 2,500. Rhodamine B (fluorescent dye) was used as a high-Schmidt-number passive scalar. The Schmidt number is about 2,100. The time-resolved particle image velocimetry (PIV) and the planar laser induced fluorescence (PLIF) technique were used to measure instantaneous two-component velocities and nondimensional concentration. Our PLIF algorithm corrects the following errors: spatiotemporal variation of local excitation intensity due to an inhomogeneous concentration field along the light path, time variation of fluorescence quantum yield, and spatiotemporal variation of incident laser intensity. The results show that the vertical profile of mean scalar can be well approximated by the error function. In contrast, the profile of scalar variance in outer region of the mixing layer cannot be approximated by the Gaussian profile. In addition, the half width of mean scalar is larger than that of the scalar variance profile.
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Amiri, Amirhossein, Reza Ghashghaei et Peyman Khosravi. « A self-starting control chart for simultaneous monitoring of mean and variance of autocorrelated simple linear profile ». Dans 2016 IEEE International Conference on Industrial Engineering and Engineering Management (IEEM). IEEE, 2016. http://dx.doi.org/10.1109/ieem.2016.7797866.
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Mohiuddin, Sheik, et Junjian Qi. « Droop-Free Distributed Control for AC Microgrids with Precisely Regulated Voltage Variance and Admissible Voltage Profile Guarantees ». Dans 2020 IEEE Power & Energy Society General Meeting (PESGM). IEEE, 2020. http://dx.doi.org/10.1109/pesgm41954.2020.9281584.
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PEREIRA, A. F. G. « Influence of the sheet thickness variability on the deep drawing of a cylindrical cup ». Dans Material Forming. Materials Research Forum LLC, 2024. http://dx.doi.org/10.21741/9781644903131-202.
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Abstract. Sheet metal forming processes are widely used in industry. The quality of formed parts can be significantly affected by various sources of uncertainty inevitably associated with the forming process. The objective of this work is to quantify the influence of thickness variability on the forming process of a cylindrical cup. Using numerical simulation, the influence of the sheet thickness variance on the evolution of the punch force versus displacement, the equivalent plastic strain distribution, the earing profile and the thickness around the cup is studied for a given cup height. Four thickness distributions with different variance values and the same average thickness value were studied. It was concluded that an increase in variance leads to an increase in thickness dispersion (at the base and curvature of the cup) and an increase in equivalent strain dispersion along the cup. The earing profile of the cup is also affected by the thickness variability, but to a lesser extent. On the other hand, the development of the punch force is not affected by the thickness variability.
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Hasan, Mubashir, Farshad Biglari, Asad Nadeem, Mazen M. Othayq, Siamack A. Shirazi et Soroor Karimi. « Uncertainty Analysis in Solid Particle Erosion Through Validation and Refinement of Experimental Data and Comparison With CFD ». Dans ASME 2024 Fluids Engineering Division Summer Meeting collocated with the ASME 2024 Heat Transfer Summer Conference and the ASME 2024 18th International Conference on Energy Sustainability. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/fedsm2024-131389.
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Abstract In the present work, gas-sand erosion experiments selected from the literature are repeated to study data validation. A standard 3-inch (76.2 mm) stainless steel elbow with a bend radius to pipe diameter ratio (r/D) equal to 1.5 is used. Wall thickness loss is measured using fixed-mounted Ultrasonic Transducers (UT) at 6 different locations on the outer wall of the investigated elbow. The flow conditions are gas-sand with 15, 23, and 31 m/s gas velocities and 75 and 300-μm sand particle sizes. A statistical approach of 99 percent confidence interval is utilized to find and remove the outliers in the data sets. Upper and lower bounds of erosion are presented to visualize the confidence of erosion data around the average profile. Moreover, additional experimental cases are studied to expand the range of data. These experimental conditions include 39 and 47 m/s gas velocities with 75 and 300-μm sand particle sizes. In the next step, the erosion data variance is calculated at different angles on the outer wall of the elbows before and after applying the uncertainty analysis. It is seen that by applying the uncertainty analysis, the variance of the experimental erosion values is reduced by a range of 20 to 99 %. The experimental erosion profiles along the outer wall of the elbow are compared with erosion profiles obtained from CFD (Computational Fluid Dynamics) performed for similar conditions. CFD contours of erosion are in agreement with the average erosion profile obtained from the experimental data.
Rapports d'organisations sur le sujet "Variance profile"
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SPECT Dopamine Transporters, Consensus QIBA Profile. Chair John Dickson et John Seibyl. Radiological Society of North America (RSNA)/Quantitative Imaging Biomarkers Alliance (QIBA), octobre 2019. https://doi.org/10.1148/qiba/20191015.
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Parkinsonism is a major health problem. Distinguishing neurodegenerative causes of parkinsonism from non-degenerative movement disorders that can mimic Parkinson’s disease (PD) has important implications for prognosis and clinical management. The goal of this QIBA Profile is to optimize the performance of Iodine-123 (123I) ioflupane single photon emission computed tomography (SPECT) for quantifying the concentration of regional cerebral dopamine transporters (DaT) in patients with movement disorders. The Claim (Section 2): This profile claims that conformance with its specifications will provide test-retest technical variance of less than 15% COV. In clinical use this might permit the ability to distinguish true biological change from measurement noise in clinical trials of participants who will be studied cross— sectionally, to aid accurate cohort recruitment and longitudinally with 123I-ioflupane. The claim is founded on observations that neurodegenerative disorders, such as idiopathic PD and Diffuse Lewy Body Dementia (DLBD), are associated with dopaminergic neuronal degeneration, which can be particularly pronounced in the substantia nigra. The degeneration of the axonal projections from the substania nigra to the basal ganglia is manifested as a loss of DaT activity. In most clinical imaging contexts where the question is about a neurodegenerative disorder, the loss is first observed in the most posterior aspect of the putamen, and then seems to march anteriorly, with left and right sides showing asymmetric changes. As a result, quantifying DaT can distinguish normal and abnormal states. The Activities (Section 3) describe what needs to be done to make measurements that reliably distinguish patients from controls with confidence. Requirements are placed on the Actors who participate in those activities as necessary to achieve the Claim. The Assessment Procedures (Section 4) for evaluating specific requirements are defined as needed. This QIBA Profile, “Quantifying Dopamine Transporters with 123Iodine Labeled Ioflupane in Neurodegenerative Disease”, addresses quantitative SPECT imaging, which is often used as a diagnostic, as well as a longitudinal biomarker of disease progression or response to treatment. It places requirements on Acquisition Devices, Technologists, Radiologists, Reconstruction Software and Image Analysis Tools involved in Subject Handling, Image Data Acquisition, Image Data Reconstruction, Image QA and Image Analysis. The requirements are focused on achieving sufficient accuracy and avoiding technical variability of the DaT measurements to distinguish neurodegenerative causes of parkinsonism from non-degenerative causes. The clinical performance target is to achieve a 95% confidence interval for the striatal binding ratio with both a reproducibility and a repeatability of +/- 15%. This document is intended to help clinicians basing decisions on this biomarker, imaging staff generating this biomarker, vendor staff developing related products, purchasers of such products, and investigators designing trials with imaging endpoints. Note that this document only states requirements to achieve the claim, not “requirements on standard of care”. Conformance to this Profile is secondary to properly caring for the patient. This QIBA Profile, and others like it addressing CT, MRI, PET and ultrasound can be found at www.qibawiki.rsna.org.
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Ultrasound Measurement of Shear Wave Speed for Estimation Liver Fibrosis, Clinically Feasible Profile. Chair David Fetzer, Stephen McAleavey et Stephen Rosenzweig. Radiological Society of North America (RSNA) / Quantitative Imaging Biomarkers Alliance (QIBA), janvier 2024. http://dx.doi.org/10.1148/qiba/20240115.
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The goal of a QIBA Profile is to help achieve a useful level of performance for a given biomarker. Profile development is an evolutionary, phased process; this Profile is in the “Clinically Feasible” (formerly “Technically Confirmed") stage. The performance claims represent expert consensus and will be empirically demonstrated at a subsequent stage. Several sites have performed the profile, found it to be practical, and expect it to achieve the claimed performance. Users of this Profile are encouraged to refer to the following site to understand the document’s context: http://qibawiki.rsna.org/index.php/QIBA_Profile_Stages. The Claim (Section 2) describes the biomarker performance. The Activities (Section 3) contribute to generating the biomarker. Requirements are placed on the Actors that participate in those activities as necessary to achieve the Claim. Assessment Procedures (Section 4) for evaluating specific requirements are defined as needed. Conformance (Section 5) regroups Section 3 requirements by Actor to conveniently check Conformance. This QIBA Profile (Ultrasound Measurement of Shear Wave Speed for Estimation of Liver Fibrosis) addresses estimation of liver fibrosis, which is often used to determine when and how to treat patients with diffuse liver disease, and also monitor progression or response to treatment. It places requirements on ultrasound scanners (acquisition devices), Scanner Manufacturer/Vendor, Technologists/Sonographers, QA (Quality Assurance) Manager, Radiologists, and Image Analysis Tools involved in pre-delivery steps, scanner installation, periodic QA procedures, subject selection and handling, SWS image acquisition, image QA, and image analysis. The requirements are focused on achieving sufficient accuracy and avoiding unnecessary variability of the estimation of liver fibrosis. Estimates of liver fibrosis are based on a measurement of shear wave speed (SWS) in the tissue using ultrasound, which in turn is based on the stiffness of the liver tissue. The clinical performance target is to achieve SWS measurements with a bias of the mean value of ≤ 5% and an overall coefficient of variation (SD/mean) of ≤ 5%. The standard against which to measure bias has not yet been fully defined, so currently there is no bias claim. At the present time, bias is determined by comparison to the measured SWS and stiffness using a Verasonics ultrasound system in a calibrated QIBA SWS phantom. Currently bias and precision depend on the magnitude of measured SWS (as determined in phantom studies) so bias and variance claims are given for three ranges of measured SWS values. Also, bias and precision depend on the conditions under which the measurements are made. Bias and precision claims are therefore also given for various measurement conditions. This document is intended to help clinicians basing decisions on this biomarker, imaging staff generating this biomarker, vendor staff developing related products, purchasers of such products, and investigators designing trials with imaging endpoints. Note that this document only states requirements to achieve the claim, not “requirements on standard of care.” Conformance to this Profile is secondary to properly caring for the patient. QIBA Profiles addressing other imaging biomarkers using CT, MRI, PET and Ultrasound can be found at https://qibawiki.rsna.org/index.php/Main_Page
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99mTc SPECT-CT, Consensus QIBA Profile. Chair Yuni Dewaraja et Robert Miyaoka. Radiological Society of North America (RSNA)/Quantitative Imaging Biomarkers Alliance (QIBA), octobre 2019. https://doi.org/10.1148/qiba/20191021.
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The quantification of 99mTc labeled biomarkers can add unique value in many different settings, ranging from clinical trials of investigation new drugs to the treatment of individual patients with marketed therapeutics. For example, goals of precision medicine include using companion radiopharmaceutical diagnostics as just-in-time, predictive biomarkers for selecting patients to receive targeted treatments, customizing doses of internally administered radiotherapeutics, and assessing responses to treatment. This Profile describes quantitative outcome measures that represent proxies of target concentration or target mass in topographically specific volumes of interest (VOIs). These outcome measures are usually expressed as the percent injected dose (i.e., radioactivity) per mL of tissue (%ID/mL), a standard uptake value ratio (SUVr), or a target-to-background ratio (TBR). In this profile, targeting is not limited to any single mechanism of action. Targeting can be based on interaction with a cell surface protein, an intracellular complex after diffusion, protein-mediated transport, endocytosis, or mechanical trapping in a capillary bed, as in the case of transarterial administration of embolic microspheres. Regardless, the profile focuses on quantification in well-defined volumes of interest. Technetium-99m based dopamine transporter imaging agents, such as TRODAT, are nearly direct links with some aspects of the predecessor profile on 123I-ioflupane for neurodegenerative disorders. (See www.qibawiki.rsna.org ) Cancer is often a base case of convenience for new material in this profile, but the intent is to create methods that can be useful in other therapeutic areas where the diseases are characterized by spatially-limited anatomical volumes, such as lung segments, or multifocal aggregations of targets, such as white blood cell surface receptors on pulmonary nodules in patients with sarcoidosis. Neoplastic masses that can be measured with x-ray computed tomography (CT) or magnetic resonance imaging (MRI) are the starting point. However, the intent is to create a profile that can be extrapolated to diseases in other therapeutic areas that are also associated with focal, or multi-focal pathology, such as pulmonary granulomatous diseases of autoimmune or infectious etiology, non-oncological diseases of organs such as polycystic kidney disease, and the like. The criteria for measurability are based on the current resolution of most SPECT-CT systems in clinical practice, and are independent of criteria for measurability in other contexts. For this SPECT profile, conformance requires that a “small” VOI must be greater than 30 mL to be measurable. It is understood that much smaller VOIs can sometimes exhibit high conspicuity on SPECT, but these use cases are beyond the scope of this profile and will not be tested for conformance in this version. It is left to individual stakeholders to show the extent to which they can achieve conformance when measuring VOIs less than 30 mL. The detection of smaller changes during clinical trials of large groups can be achieved by referring to the QIBA companion guidance on powering trials. The Claims (Section 2) asserts that compliance with the specifications described in this Profile will produce cross sectional estimates of the concentration of radioactivity [kBq/mL] in a volume of interest (VOI) or a target-to-background ratio (TBR) within a defined confidence interval (CI), and distinguish true biological change from system variance (i.e., measurement error) in individual patients or clinical trials of many patients who will be studied longitudinally with 99mTc SPECT agents. Both claims are founded on observations that target density varies between patients with the same disease as well as within patients with multi-focal disease. The Activities (Section 3) describes the requirements that are placed on the Actors who need to achieve the Claim. Section 3 specifies what the actors must do in order to estimate the amount of radioactivity in a volume of interest, expressed in kBq/mL (ideal) or as a TBR (acceptable) within a 95% CI surrounding the true value. Measurands such as %ID/mL are targets for nonclinical studies in animal models that use terminal sacrifice to establish ground truth for imaging studies. TBRs can be precarious, as the assumptions that depend on the physiology of the background regions matching the volume of interest can be hard to accept sometimes. It is up to each individual stakeholder to qualify the background regions used in their own use case. This profile qualifies only a few in some very limited contexts as examples. The Assessment Procedures (Section 4) for evaluating specific requirements are defined as needed. The requirements are focused on achieving sufficient accuracy and avoiding unnecessary variability of the measurements. The clinical performance target is to achieve a 95% confidence interval for concentration in units of kBq/mL (kilobequerels per milliliter) or %ID/mL (percent injected dose per milliliter) or TBR with both a reproducibility and a repeatability of +/- 8% within a single individual under zero-biological-change conditions. This document is intended to help clinicians basing decisions on these biomarkers, imaging staffs generating measurements of these biomarkers, vendors who are developing related products, purchasers of such products, and investigators designing trials. Note that this document only states requirements to achieve the claims, not “requirements on standard of care” nor compliance with any particular protocol for treating participants in clinical trial settings. Conformance to this Profile is secondary to properly caring for patients or adhering to the requirements of a protocol. QIBA Profiles addressing other imaging biomarkers using CT, MRI, PET and Ultrasound can be found at www.qibawiki.rsna.org.
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Ziegler, Nancy, Nicholas Webb, Adrian Chappell et Sandra LeGrand. Scale invariance of albedo-based wind friction velocity. Engineer Research and Development Center (U.S.), mai 2021. http://dx.doi.org/10.21079/11681/40499.
Texte intégralRésumé :
Obtaining reliable estimates of aerodynamic roughness is necessary to interpret and accurately predict aeolian sediment transport dynamics. However, inherent uncertainties in field measurements and models of surface aerodynamic properties continue to undermine aeolian research, monitoring, and dust modeling. A new relation between aerodynamic shelter and land surface shadow has been established at the wind tunnel scale, enabling the potential for estimates of wind erosion and dust emission to be obtained across scales from albedo data. Here, we compare estimates of wind friction velocity (u*) derived from traditional methods (wind speed profiles) with those derived from the albedo model at two separate scales using bare soil patch (via net radiometers) and landscape (via MODIS 500 m) datasets. Results show that profile-derived estimates of u* are highly variable in anisotropic surface roughness due to changes in wind direction and fetch. Wind speed profiles poorly estimate soil surface (bed) wind friction velocities necessary for aeolian sediment transport research and modeling. Albedo-based estimates of u* at both scales have small variability because the estimate is integrated over a defined, fixed area and resolves the partition of wind momentum be-tween roughness elements and the soil surface. We demonstrate that the wind tunnel-based calibration of albedo for predicting wind friction velocities at the soil surface (us*) is applicable across scales. The albedo-based approach enables consistent and reliable drag partition correction across scales for model and field estimates of us* necessary for wind erosion and dust emission modeling.
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Phelan, Thomas M. On the Optimality of Differential Asset Taxation. Federal Reserve Bank of Cleveland, février 2025. https://doi.org/10.26509/frbc-wp-201917r2.
Texte intégralRésumé :
In this paper I study the optimality of differential asset taxation in an environment with entrepreneurs and workers in which output is stochastic and entrepreneurs can misreport profits and abscond with capital. I show that a stationary efficient allocation may be implemented as an equilibrium with endogenous collateral constraints, transfers to newborns, and linear taxes on profits, investment, and interest. Further, these taxes differ from one another and serve distinct purposes. The profits tax shares risk and depends solely on the severity of the misreporting friction, while the remaining instruments determine the efficient mean and variance of entrepreneurs' consumption growth.
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Tran, Thi Hong Van, Bartłomiej Woś, Tomasz Wanic, Marcin Pietrzykowski et Agnieszka Józefowska. Impact of charcoal and tree species on forest soil recovery after fire disturbance Dataset. Publishing House of the University of Agriculture in Krakow, 2025. https://doi.org/10.15576/repourk/2025.1.1.
Texte intégralRésumé :
This dataset examines the impact of charcoal and tree species on forest soil recovery post-fire, encompassing soil profile characteristics, particle size distribution (granulometry), and chemical properties. It includes measurements from eight variants, considering four tree species and two land preparation methods for regeneration: with and without charcoal removal. The methodology and study location are described in the publication.
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MR (Diffusion-Weighted Imaging (DWI) of the Apparent Diffusion Coefficient (ADC), Clinically Feasible Profile. Chair Michael Boss, Dariya Malyarenko et Daniel Margolis. Radiological Society of North America (RSNA) / Quantitative Imaging Biomarkers Alliance (QIBA), décembre 2022. http://dx.doi.org/10.1148/qiba/20221215.
Texte intégralRésumé :
The goal of a QIBA Profile is to help achieve a useful level of performance for a given biomarker. The Claim (Section 2) describes the biomarker performance and is derived from the body of scientific literature meeting specific requirements, in particular test-retest studies. The Activities (Section 3) contribute to generating the biomarker. Requirements are placed on the Actors that participate in those activities as necessary to achieve the Claim. Assessment Procedures (Section 4) for evaluating specific requirements are defined as needed to ensure acceptable performance. Diffusion-Weighted Imaging (DWI) and the Apparent Diffusion Coefficient (ADC) are being used clinically as qualitative (DWI) and quantitative (ADC) indicators of disease presence, progression or response to treatment. Use of ADC as a robust quantitative biomarker with finite confidence intervals places additional requirements on Sites, Acquisition Devices and Protocols, Field Engineers, Scanner Operators (MR Technologists, Radiologists, Physicists and other Scientists), Image Analysts, Reconstruction Software and Image Analysis Tools. Additionally, due to the intrinsic dependence of measured ADC values on biophysical tissue properties, both the Profile Claims and the associated scan protocols (Section 3.6.2) are organ-specific. All of these are considered Actors involved in Activities of Acquisition Device Pre-delivery and Installation, Subject Handling, Image Data Acquisition, Reconstruction, Registration, ADC map generation, Quality Assurance (QA), Distribution, Analysis, and Interpretation. The requirements addressed in this Profile are focused on achieving ADC values with minimal systematic bias and measurement variability. DISCLAIMER: Technical performance of the MRI system can be assessed using a phantom having known diffusion properties, such as the QIBA DWI phantom. The clinical performance target is to achieve a 95% confidence interval for measurement of ADC with a variable precision depending on the organ being imaged and assuming adequate technical performance requirements are met. While in vivo DWI/ADC measurements have been performed throughout the human body, this Profile focused on four organ systems, namely brain, liver, prostate, and breast as having high clinical utilization of ADC with a sufficient level of statistical evidence to support the Profile Claims derived from the current peer-reviewed literature. In due time, new DWI technologies with proven greater performance levels, as well as more organ systems will be incorporated in future Profiles. This document is intended to help a variety of users: clinicians using this biomarker to aid patient management; imaging staff generating this biomarker; MRI system architects developing related products; purchasers of such products; and investigators designing clinical trials utilizing quantitative diffusion-based imaging endpoints. Note that this document only states requirements specific to DWI to achieve the claim, not requirements that pertain to clinical standard of care. Conforming to this Profile is secondary to proper patient care.
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Pineda-Mendez, Raul, Qiming Guo, Noshin Ahmad, Mario A. Romero et Andrew P. Tarko. Incorporating Time-Dependent Data for Proactive Safety Management. Purdue University, 2024. http://dx.doi.org/10.5703/1288284317700.
Texte intégralRésumé :
This study proposed a risk-based safety management framework to supplement the current crash-based safety management system. The proposed tool considers time-dependent factors (e.g., hourly traffic, speed features, weather conditions, signal controls) to help justify operational measures for safety improvements (e.g., variable message signs, variable speed limits, warnings). These selected temporal factors subsequently were included in the developed sequential logit models; and those models, applied hour by hour, were then used to estimate the crash probability and severity level. Two typical roadway elements, rural freeway segments and signalized intersections, were also included in the analysis. The obtained crash risk profiles can be used to predict the expected number of crashes in periods when the operational safety countermeasures are expected to be active based on certain triggering conditions (e.g., traffic, weather, nighttime). These results, together with crash modification factors, may be used in the benefit and cost analysis process to justify the application of specific countermeasures.
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Azar, Pablo, Adrian Casillas et Maryam Farboodi. Information and Market Power in DeFi Intermediation. Federal Reserve Bank of New York, mai 2024. http://dx.doi.org/10.59576/sr.1102.
Texte intégralRésumé :
The decentralized nature of blockchain markets has given rise to a complex and highly heterogeneous market structure, gaining increasing importance as traditional and decentralized (DeFi) finance become more interconnected. This paper introduces the DeFi intermediation chain and provides theoretical and empirical evidence for private information as a key determinant of intermediation rents. We propose a repeated bargaining model that predicts that profit share of Ethereum market participants is positively correlated with their private information, and employ a novel instrumental variable approach to show that a 1 percent increase in the value of intermediaries’ private information leads to a 1.4 percent increase in their profit share.
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Thomas, Tucker et Cowell. PR-283-10204-R01 Prevent Variable Guide Vane Lock-up - Solar Gas Turbines with Intermittent Operation. Chantilly, Virginia : Pipeline Research Council International, Inc. (PRCI), janvier 2016. http://dx.doi.org/10.55274/r0010856.
Texte intégralRésumé :
A study was completed to demonstrate that a guide vane field refurbishment process and improved maintenance practices are effective at preventing corrosion and lock-up of the guide vanes of Solar�s Taurus 60-7802S gas turbine operated in intermittent duty. A Taurus 60 engine located at Dominion�s Crayne compressor station was refurbished and operated over a five year period using maintenance practices to slow the build-up of corrosion. The visible condition of the VGV assembly on this Test Unit was monitored and the guide vane actuator force measured to assess if corrosion build-up was occurring. A second co-located Taurus 60 served as a Control Unit to validate that the environment and operating profile were conducive to corrosion build-up. The Control Unit was not modified with the exception that electric actuators were installed on both units so that the VGV actuator force could be measured. The engines logged over 18,000 hours of operation during the test period after which, both units were pulled for overhaul. A detailed inspection and assessment was completed with extensive photographic documentation of the condition of the hardware. The actuator force measured during the start sequence for each of the engines was compared. The Test Unit actuator force varied from 180 to 265 lbf, while the Control Unit had a considerably larger variation of 170 to 315 lbf. The Control Unit suffered a guide vane lock-up event in June of 2014.