Search results for " modelling"

Physico-chemical evolution of low-pH cements : influence of the temperature and the retention mechanisme of alkalins

2010

Because of their high alkalinity, Portland cement (OPC)-based materials may have deleterious effects in an underground waste repository. A solution would be to use low-alkalinity cements (also referred as low-pH cements) generating interstitial solutions with a reduced pH (11 instead of 13.5 for OPC), and thus showing an improved chemical compatibility with the repository environment. In this work, the investigated formulations were based on binary (OPC / silica fume) or ternary (OPC / silica fume / slag or fly ash) blends, with high substitution levels of CEM I (from 30% to 80%). This research project met two main objectives: (i) study the chemical evolution of low-pH cements at 50°C or 80…

Perceived Value in Tourism: A PLSPM Approach

2015

This paper examines the concept of perceived value in rural tourism referred to the specific context of Sicilian holiday farms. Herein main dimensions composing the rural tourist perceived value (RTPV) are discussed. Using Partial Least Squares Path Modelling (PLSPM) –a statistical technique especially suitable for exploratory purposes with small samples – a theoretical structural model of the multidimensional structure of RTPV is tested and the causal relationships among RTPV and its dimensions (Functional, Convenience, Emotional and Educational) and among RTPV and tourists’ satisfaction and loyalty are explored. Results from a field survey on 350 tourists give a contribution in terms of i…

How upper secondary students solve algebraic word problems in the area of mathematical modelling : A case study of one group of Norwegian students

2019

Masteroppgave matematikkdidaktikk MA500 - Universitetet i Agder 2019 For å imøtekomme nye utfordringer på skolen, i jobb og i livet, kan elever ha behov for åtilpasse og utvide den matematikken de kan. Dette krever at elever evner, i noen grad, åsette skolematematikken i forbindelse med hverdagslige kontekster og motsatt. Matema-tisk modellering er en av de hensiktsmessige mediene for å støtte sammenhengen mellomskolematematikken og virkeligheten. Forskning har vist at det er en sterk tilbøyelighet ipensumet mot matematisk modellering og at i stedet høynivå matematikk er ansett somviktig, mest på videregående nivå. Igjen, forskning viser at elever har større utfordringermed abstrakte (fakta…

Statistical models and inference for spatial point patterns with intensity-dependent marks

2009

Molecular Modelling on Leptin and the Ob Receptor as anti-obesity target

2012

Obesity is a chronic pathology with multi-factorial aetiology, characterized by extreme body weight due to storing of fat in the adipose tissue, caused by an increase of caloric income, decrease of energetic intake, or both. The body weight control is a mechanism finely regulated by several hormonal, metabolic, and nervous pathways. Recessive homozygous mutations in the ob/ob and db/db mouse strain cause extreme obesity. The products of the ob and db genes are leptin and its receptor, respectively (1,2). The leptin receptor is critical for energy homeostasis and regulation of food uptake. Leptin is a 16 kDa hormone that is mainly secreted by fat cells into the bloodstream. Under normal circ…

Slope Failures and MTDs along a Cretaceous Escarpment in Western Sicily (Italy)

2018

In the last decades, many contributions have examined the Mass Transport Deposits (MTDs) in both modern and ancient examples for the comprehension of the sedimentary dynamics along the carbonate escarpments. Such sedimentary bodies have a great economic significance, since they are widely considered prone to the development of petroleum systems. In particular, MTDs from Cretaceous escarpments are well known from many regions of the world, since they are typically rich in rudists aragonite fragments determining high percentages of porosity. In these respect the deep knowledge on the facies architecture of these depositional systems is of broad interest as can offer examples for the predictio…

A simple model of income, aggregate demand and the process of credit creation by private banks

2013

This paper presents a small macroeconomic model describing the main mechanisms of the process of creation by the private banking system. The model is composed of a core unit-where the dynamics of income, credit and aggregate demand are determined-and a set of sectoral accounts that ensure its stock-flow consistency. In order to grasp the role of credit and banks on the functioning of the economic system we make an explicit distinction between planned and realized variables, thanks to which, while maintaining the ex-post accounting consistency, we are able to introduce an ex-ante wedge between current aggregate income and planned expenditure. Private banks are the only economic agents capabl…

Modelling and Identification of Mg(OH)2 precipitation kinetics from highly concentrated Mg2+ solutions

Identification of Mg(OH)2 precipitation kinetics with population balances and CFD

Magnesium silicate hydrate (M-S-H) characterization : temperature, calcium, aluminium and alkali

2017

The various options to store radioactive wastes in deep geological strata considered in France or Switzerland include the use of large volumes of cementitious materials for infrastructure in contact with argillaceous rocks. So-called low-pH binders were developed to minimize disruption to the surrounding rock by the alkaline plume. Studies conducted on the interaction zone between concrete and clay systematically highlighted the formation of magnesium silicate phases including magnesium silicate hydrate (M-S-H) at the interfaces, which can presently be modeled only partially due to incomplete thermodynamic data. The purpose of this study was to characterize these phases in temperature, alum…