Search results for "modeling"
showing 10 items of 4489 documents
Detailed modeling of the kraft pulping chemistry : carbohydrate reactions
2020
The article introduces a detailed model for carbohydrate chemistry in kraft pulping. This article is continuation to the modeling work carried out for hot water extraction and chemical pulp bleaching. The model includes galactoglucomannan, xylan, and cellulose acid–base equilibria, in addition to peeling, stopping, and alkaline hydrolysis reactions of the same carbohydrates, as well as hexenuronic acid formation and degradation reactions. The Arrhenius parameters were applied from the literature or regressed against experimental data in the present study. The model is very successful in predicting the experimental data of carbohydrate reactions during kraft pulping. Many features of the pul…
Modeling biomass char gasification kinetics for improving prediction of carbon conversion in a fluidized bed gasifier
2014
Gasification of biomass in a fluidized bed (FB) was modeled based on kinetic data obtained from previously conducted thermo- gravimetic analysis. The thermogravimetric analysis experiments were designed to closely resemble conditions in a real FB gasifier by using high sample heating rates, in situ devolatilization and gas atmospheres of H 2 O / H 2 and CO 2 / CO mixtures. Several char kinetic models were evaluated based on their ability to predict char conversion based on the thermogravimetric data. A modified version of the random pore model was shown to provide good fitting of the char reactivity and suitability for use in a reactor model. An updated FB reactor model which incorporates t…
Exploring Oscillatory Dysconnectivity Networks in Major Depression During Resting State Using Coupled Tensor Decomposition
2022
Dysconnectivity of large-scale brain networks has been linked to major depression disorder (MDD) during resting state. Recent researches show that the temporal evolution of brain networks regulated by oscillations reveals novel mechanisms and neural characteristics of MDD. Our study applied a novel coupled tensor decomposition model to investigate the dysconnectivity networks characterized by spatio-temporal-spectral modes of covariation in MDD using resting electroencephalography. The phase lag index is used to calculate the functional connectivity within each time window at each frequency bin. Then, two adjacency tensors with the dimension of time frequency connectivity subject are constr…
Molecular dynamics simulations of heavy ion induced defects in SiC Schottky diodes
2018
Heavy ion irradiation increases the leakage current in reverse-biased SiC Schottky diodes. This work demonstrates, via molecular dynamics simulations, that a combination of bias and ion-deposited energy is required to produce the degradation peerReviewed
Modelling of rotations by using matrix solutions of nonlinear wave equations
2007
A family of matrix solutions of nonlinear wave equations is extended and its application to modelling is given. It is shown that a similarity transformation, induced by the matrix solution, is equivalent to the rotation. Matrix solutions are used for modelling helical motions and vortex rings, simultaneous rotations and particles collision, mapping contraction and pulsating spheres. Geometrical interpretation of the doubling of rotation angle in each step of sequential mapping contraction is given. First Published Online: 14 Oct 2010
Job Insecurity and Depressive Symptoms in Mothers and Adolescents: A Dyadic Study
2021
AbstractIn this study, we examined whether maternal perceived job insecurity (JI) affected depressive symptoms in their adolescent children. Specifically, we tested a mediator-moderator model in which we hypothesized that maternal JI was related to adolescent depressive symptoms indirectly via maternal depressive symptoms. Most importantly, we also explored whether this indirect path was moderated by two buffering resources, i.e., maternal off-job recovery and adolescent self-esteem. There is little research on the effects of parental JI on adolescent children from the viewpoint of buffering moderators. Due to growing insecurity in the labor markets we need more information about resources …
A coupled discontinuous Galerkin-Finite Volume framework for solving gas dynamics over embedded geometries
2021
Author(s): Gulizzi, Vincenzo; Almgren, Ann S; Bell, John B | Abstract: We present a computational framework for solving the equations of inviscid gas dynamics using structured grids with embedded geometries. The novelty of the proposed approach is the use of high-order discontinuous Galerkin (dG) schemes and a shock-capturing Finite Volume (FV) scheme coupled via an $hp$ adaptive mesh refinement ($hp$-AMR) strategy that offers high-order accurate resolution of the embedded geometries. The $hp$-AMR strategy is based on a multi-level block-structured domain partition in which each level is represented by block-structured Cartesian grids and the embedded geometry is represented implicitly by a…
Mathematical modeling and competencies for biology students
2017
International audience; The research aims at introducing modeling tasks with an ultimate goal to engage students more actively into learning mathematics through tasks that are biologically 'colored'. My focus is on the individual progression (if any) of students' mathematical competencies during a sequence of modeling sessions as part of their first year mathematics. My goal is to explore the nature of progression within the competency profile of participating student, the relation between modeling processes and this progression and what transformations are applied in these sets of competencies.
Why do we enjoy creative tasks? Results from a multigroup randomized controlled study
2016
Previous studies have linked positive emotions with creativity, but it remains unknown why creative activities may enhance positive emotions. We tested how creative tasks influence autonomous self-expression and task absorption, and whether this in turn increases positive emotions. Data from 478 participants were divided into four language samples (English, German, Italian, and Polish) and analyzed in a series of multigroup structural equation models. The indirect effects were replicated in all samples. Creative tasks enhanced positive emotions through an increase in autonomy. However, participants who solved creative tasks also reported lower task absorption, and this has hindered their ex…
Students’ multiple state goals as a function of appraisals, trait goals, and their interactions
2017
Abstract Although many motivational theories have emphasized that person- and situation-based aspects should be recognized simultaneously when explaining actual learning behavior, not much is known about the occurrence of state goals. The model of adaptive learning (Boekaerts & Niemivierta, 2000) proposes that state goals are influenced by trait goals, perceptions of the situation (i.e., appraisals), and interactions between trait goals and appraisals. Nevertheless, empirical evidence for this model is scarce. The present study aimed to overcome this research deficit by integrating trait goals and appraisals as well as their interactions in explaining state goals in authentic learning episo…