Search results for "Statistical"
showing 10 items of 4960 documents
Multiple Classifiers and Data Fusion for Robust Diagnosis of Gearbox Mixed Faults
2019
Detection and isolation of single and mixed faults in a gearbox are very important to enhance the system reliability, lifetime, and service availability. This paper proposes a hybrid learning algorithm, consisting of multilayer perceptron (MLP)- and convolutional neural network (CNN)-based classifiers, for diagnosis of gearbox mixed faults. Domain knowledge features are required to train the MLP classifier, while the CNN classifier can learn features itself, allowing to reduce the required knowledge features for the counterpart. Vibration data from an experimental setup with gearbox mixed faults is used to validate the effectiveness of the algorithms and compare them with conventional metho…
Comprehensive Strategy for Proton Chemical Shift Prediction: Linear Prediction with Nonlinear Corrections
2014
A fast 3D/4D structure-sensitive procedure was developed and assessed for the chemical shift prediction of protons bonded to sp3carbons, which poses the maybe greatest challenge in the NMR spectral parameter prediction. The LPNC (Linear Prediction with Nonlinear Corrections) approach combines three well-established multivariate methods viz. the principal component regression (PCR), the random forest (RF) algorithm, and the k nearest neighbors (kNN) method. The role of RF is to find nonlinear corrections for the PCR predicted shifts, while kNN is used to take full advantage of similar chemical environments. Two basic molecular models were also compared and discussed: in the MC model the desc…
A comparative molecular dynamics-phase-field modeling approach to brittle fracture
2016
Abstract In this work, a novel comparative method for highly brittle materials such as aragonite crystals is proposed, which provides an efficient and accurate in-sight understanding for multi-scale fracture modeling. In particular, physically-motivated molecular dynamics (MD) simulations are performed to model quasi-static brittle crack propagation on the nano-scale and followingly compared to macroscopic modeling of fracture using the phase-field modeling (PFM) technique. A link between the two modeling schemes is later proposed by deriving PFM parameters from the MD atomistic simulations. Thus, in this combined approach, MD simulations provide a more realistic meaning and physical estima…
Flexible design of multifocal metalenses based on autofocused Airy beams
2018
Extreme miniaturization of on-demand optical devices such as ultrathin lenses is currently leading to significant advancements in manufacturing novel materials and nanotechnologies. Flexibility and tunability of engineered layouts enable efficient integration of complex photonic modules. In this regard, here we propose an autofocused Airy (AFA)-based metalens that operates, depending on the molded phase profile, as a multifocal focusing lens, which to the best of our knowledge has not been reported before. To do this, we call attention to the fact that the two conjugate focal points of an AFA beam can be brought into real space by applying a proper convex lens phase profile. Considering ful…
A study on the statistical properties of double hoyt fading channels
2009
This paper deals with a study on the statistical properties of narrowband amplify-and-forward relay fading channels for Hoyt multipath propagation environments. We consider the basic radio link topology, where only one fixed relay station is used for the amplification. In this case, the envelope of the signal received over the overall multipath channel is modeled by the so-called double Hoyt fading process. Considering this multipath propagation channel model, analytical expressions for the first and second order statistics are provided. Specifically, the mean value, variance, probability density function (PDF), level-crossing rate (LCR), and average duration of fades (ADF) of double Hoyt p…
Automated quality control of next generation sequencing data using machine learning
2019
AbstractControlling quality of next generation sequencing (NGS) data files is a necessary but complex task. To address this problem, we statistically characterized common NGS quality features and developed a novel quality control procedure involving tree-based and deep learning classification algorithms. Predictive models, validated on internal data and external disease diagnostic datasets, are to some extent generalizable to data from unseen species. The derived statistical guidelines and predictive models represent a valuable resource for users of NGS data to better understand quality issues and perform automatic quality control. Our guidelines and software are available at the following …
Alteraciones osteoarticulares en el músico adulto mayor de instrumentos viento-madera
2021
espanolRESUMEN Objetivo: Valorar si existen cambios a nivel bucodental en adultos mayores, instrumentistas de viento-madera por el uso del instrumento a lo largo de mas de 35 anos de profesion y compararlos con un grupo control. Metodologia: Estudio de tipo observacional, descriptivo de corte transversal, entre musicos profesionales, adultos mayores, de 60 anos o mas, con mas de 35 anos de profesion y que toquen instrumentos de "viento-madera". La muestra inicial de estudio estaba formada por 57 musicos. El instrumento de recogida de datos utilizado se ha elaborado de forma exclusiva. El analisis estadistico se llevo a cabo mediante SPSS Statistics 23.0. Resultados: Media de edad 63 ± 1,28 …
Do Firms Share the Same Functional Form of Their Growth Rate Distribution? A New Statistical Test
2011
We propose a hypothesis testing procedure to investigate whether the same growth rate distribution is shared by all the firms in a balanced panel or, more generally, whether they share the same functional form for this distribution, without necessarily sharing the same parameters. We apply the test to panels of US and European Union publicly quoted manufacturing firms, both at the sectoral and at the subsectoral NAICS levels. We consider the following null hypotheses about the growth rate distribution of the individual firms: i) an unknown shape common to all firms, with all the firms sharing also the same parameters, or with the firm variance related to its firm size through a scaling rela…
The University of Valencia’s computerized word pool
1988
This paper presents the University of Valencia’s computerized word pool. This is a database that includes 16,109 Spanish words, together with 11 psychological variables for limited groups of items. The purpose behind the creation of this database was to have available a large quantity of verbal stimuli in a well-controlled system, ready for automatic selection. The description includes a summary of statistics on each of the 11 psychological variables, together with a correlational and factor analysis of them. This statistical analysis produces results close to those obtained for equivalent English material.
A word prediction methodology for automatic sentence completion
2015
Word prediction generally relies on n-grams occurrence statistics, which may have huge data storage requirements and does not take into account the general meaning of the text. We propose an alternative methodology, based on Latent Semantic Analysis, to address these issues. An asymmetric Word-Word frequency matrix is employed to achieve higher scalability with large training datasets than the classic Word-Document approach. We propose a function for scoring candidate terms for the missing word in a sentence. We show how this function approximates the probability of occurrence of a given candidate word. Experimental results show that the proposed approach outperforms non neural network lang…