Search results for "Linear"
showing 10 items of 7165 documents
Tasks for enriching the understanding of the concept of linear span
2018
International audience; The concept of linear span is one of the first abstract notions that students encounter in a course on Linear Algebra. Using the theoretical construct of concept image and concept definition (Tall & Vinner, 1981) along with observations about teaching and learning Linear Algebra, we present two tasks designed to enrich students' concept image regarding linear span. These tasks could be included in a problem workshop of an introductory university course on Linear Algebra. Each task is carefully created and/or selected so as to foster the ground for potential conflict factors to arise and be confronted. A preliminary evaluation shows that the tasks are well received by…
Preservice teachers implementing a nonlinear physical education pedagogy
2019
Background\ud In recent years, there has been considerable interest in the evolution of physical education teaching practice from a traditional teacher-centred approach to a student-centred approach. Consequently, research has focused on questions about the changing conceptions of the teaching and learning process, that is, from how ‘we’ teach to how ‘they’ learn. A contemporary theoretical model of the teaching and learning process could underpin learning design and delivery adopted in physical education. The constraints-led approach (CLA) is a viable alternative as its practice design and delivery is grounded in the contemporary motor learning theory of ecological dynamics within a nonlin…
Non-Linear Inductors Characterization in Real Operating Conditions for Power Density Optimization in SMPS
2021
The exploitation of power inductors outside their linear region in switching converters can be achieved by raising the current until a decreasing of the inductance can be noticed. It allows using a smaller magnetic core increasing the power density of the converter. On the other hand, a detailed description of the magnetization curve including the temperature is required. Since this information is often not included in the inductor’s datasheets, this paper shows how to identify the behavior of an inductor when it is operated up to saturation and its temperature rises. In order to characterize the inductor in real operating conditions, a dedicated measurement rig has been developed. It consi…
A Data-Driven Approach for Studying the Influence of Carbides on Work Hardening of Steel
2022
This study proposes a new approach to determine phenomenological or physical relations between microstructure features and the mechanical behavior of metals bridging advanced statistics and materials science in a study of the effect of hard precipitates on the hardening of metal alloys. Synthetic microstructures were created using multi-level Voronoi diagrams in order to control microstructure variability and then were used as samples for virtual tensile tests in a full-field crystal plasticity solver. A data-driven model based on Functional Principal Component Analysis (FPCA) was confronted with the classical Voce law for the description of uniaxial tensile curves of synthetic AISI 420 ste…
High-precision mass measurement of $^{168}$Yb for verification of nonlinear isotope shift
2020
The absolute mass value of $^{168}$Yb has been directly determined with the JYFLTRAP Penning trap mass spectrometer at the Ion Guide Isotope Separator On-Line (IGISOL) facility. A more precise value of the mass of $^{168}$Yb is needed to extract possible signatures of beyond standard model physics from high-precision isotope shift measurements of Yb atomic transition frequencies. The measured mass-excess value, ME($^{168}$Yb) = $-$61579.846(94) keV, is 12 times more precise and deviates from the Atomic Mass Evaluation 2016 value by 1.7$\sigma$. The impact on precision isotope shift studies of the stable Yb isotopes is discussed.
Learning non-linear time-scales with kernel -filters
2009
A family of kernel methods, based on the @c-filter structure, is presented for non-linear system identification and time series prediction. The kernel trick allows us to develop the natural non-linear extension of the (linear) support vector machine (SVM) @c-filter [G. Camps-Valls, M. Martinez-Ramon, J.L. Rojo-Alvarez, E. Soria-Olivas, Robust @c-filter using support vector machines, Neurocomput. J. 62(12) (2004) 493-499.], but this approach yields a rigid system model without non-linear cross relation between time-scales. Several functional analysis properties allow us to develop a full, principled family of kernel @c-filters. The improved performance in several application examples suggest…
Análisis de métodos de validación cruzada para la obtención robusta de parámetros biofísicos
2015
[EN] Non-parametric regression methods are powerful statistical methods to retrieve biophysical parameters from remote sensing measurements. However, their performance can be affected by what has been presented during the training phase. To ensure robust retrievals, various cross-validation sub-sampling methods are often used, which allow to evaluate the model with subsets of the field dataset. Here, two types of cross-validation techniques were analyzed in the development of non-parametric regression models: hold-out and k-fold. Selected non-parametric linear regression methods were least squares Linear Regression (LR) and Partial Least Squares Regression (PLSR), and nonlinear methods were…
Association of basal forebrain volumes and cognition in normal aging.
2013
The basal forebrain cholinergic system (BFCS) is known to undergo moderate neurodegenerative alterations during normal aging and severe atrophy in Alzheimer's disease (AD). It has been suggested that functional and structural alterations of the BFCS mediate cognitive performance in normal aging and AD. But, it is still unclear to what extend age-associated cognitive decline can be related to BFCS in normal aging. We analyzed the relationship between BFCS volume and cognition using MRI and a comprehensive neuropsychological test battery in a cohort of 43 healthy elderly subjects spanning the age range from 60 to 85 years. Most notably, we found significant associations between general intell…
A model of oil burnout from glass fabric
1997
A mathematical model is proposed for the process of the removal (by burning) of oil contained in a glass fibre insulation fabric manufactured in Latvia. The small aspect ratio of the fabric allows simplifications to the modelling which reduce the problem to a single nonlinear ordinary differential equation. When the effects of reflected radiation are also included, the differential equation is supplemented by two integral equations. Predictions of the position of the ‘burning zone’ accord well with observations made at the factory. The effect of the inclusion of extra heating chambers is also examined, and it is found that the temperature gradient in the fabric may be greatly decreased in t…
The influence of climate change on the soil organic carbon content in Italy from 1961 to 2008
2011
Abstract Soils are the biggest carbon store in the world (1500 Gt, e.g. 1.5 × 10 21 g). The European Commission indicates the accounting of soil organic carbon (SOC) variations in space and time as the first step in the strategy for soil protection. It is indeed necessary in evaluating the risk of soil organic matter decline and soil biodiversity decline, and when evaluating the role played by soils in global CO 2 accounting. Previous maps of SOC variations in Italy did not consider the direct effect of climate. There is a marked inter-dependence between SOC and climate. SOC increases with the increase in precipitations and decreases with a rise in temperatures. It is also known that land …