Search results for "modeling"

A graph colouring model for assigning a heterogeneous workforce to a given schedule

1996

Abstract We analyze a heterogeneous workforce assignment problem in which the minimum number of workers required to carry out a machine load plan is calculated. The problem is formulated as a restricted vertex colouring problem and a branch and bound algorithm is presented. The special characteristics of the graph to be coloured allow an efficient implementation of the branch and bound. Computational results show that the algorithm can solve problems of 50 activities, 5, 10 and 15 machines and between 2 to 15 different types of workers in just a few seconds.

2019

Abstract. The cumulative occurrence of heavy precipitation and flood events during recent years in various Central European locations emphasises the urgent need to improve extreme rainfall observations and forecasts. Precipitation gauges based on a weighing system allow the recording of intense short-term precipitation events with a very high temporal resolution (down to 1 min). In this study, observational data that were collected during the period 2000 to 2016 for 126 stations of two corresponding measuring networks in the Central German state of Hesse were investigated for the first time to answer the following questions: (1) Are the recorded high-resolution precipitation data plausible …

SARS-CoV-2 RNA in wastewater anticipated COVID-19 occurrence in a low prevalence area

2020

Preprint disponible en http://hdl.handle.net/10261/209125

Neural network-based models for a vibration suppression system equipped with MR brake

2012

This paper is devoted to the modeling and simulation of a full-scale commercially available magnetorheological (MR) brake installed in a semi-active suspension (SAS) system. The analysis of the Bouc-Wen and Dahl mathematical models of MR damper is presented. Influence of their parameters on the response is explored. Subsequently, by using the neural networks, the parameters characterizing each model are estimated. This makes it possible to perform the comparative analysis of the suggested damper models responses with the measured experimental results. The novelty of the presented methodology is the application of artificial intelligence methods to estimate model parameters of a MR brake uti…

Stochastic dynamic analysis of structures with fractional viscoelastic constitutive laws

The main purpose of this thesis is to provide a new way to correctly perform stochastic analysis of structures with viscoelastic constitutive law. The reason for this kind of problem relates the fact that structures with viscoelastic materials are built in many areas of mechanical, civil and aerospace engineering. To perform this kind of stochastic analysis there are two fundamental problems. That is, the mechanical description of the viscoelastic phenomenon, and the correct representation of the external loads. Both of these problems are addressed and solved by the proposed modeling that involves some advanced mathematical tools. The reason to describe materials as viscoelastic is given by…

Three dimensional numerical simulation of wind driven flows in closed channels and basins

2008

In the paper, a fully 3D finite-volume numerical model is developed and employed for the prediction of wind-induced flows in a regular channel and in a square basin with a complex bathymetry. Numerical results are compared with laboratory experiments.Numerical tests are then performed to investigate whether simplifying assumptions about the pressure distribution and the turbulente stresses representation can be employed in the simulation of wind-driven flows. The hydrostatic pressure assumption, resulting in the use of “quasi-3D” models, proved to be reasonably acceptable in order to obtain the vertical profile of the streamwise velocity component away from the boundaries. The quasi-3D mode…

Is Age Just a Number? Cognitive Reserve as a Predictor of Divergent Thinking in Late Adulthood

2016

The purpose of the study was to test a model of causal relationships among cognitive reserve (CR), personality variables such as Neuroticism and Openness to experience, and divergent thinking (DT), independently evaluating performance in different domains (verbal and graphic). It was hypothesized that CR, Openness, and Neuroticism would each directly influence verbal and graphic DT. A total of 135 subjects between 55 and 84 years old participated in the study and were interviewed in individual sessions. For a correct fit Neuroticism was eliminated from the measurement model. The goodness-of-fit indexes of the measurement model, the adequate composite reliability index and the discriminant v…

Towards an Ontology for Information Systems Development—A Contextual Approach

2007

This chapter presents an ISD ontology, which aims to provide an integrated conceptualization of ISD through anchoring it upon a contextual approach. The ISD ontology is composed of concepts, relationships, and constraints referring to purposes, actors, actions, and objects of ISD. It is presented as a vocabulary with explicit definitions and in meta models in a UML-based ontology representation language. We believe that although not complete the ISD ontology can promote the achievement of a shared understanding of contextual aspects in ISD. It can be used to analyze and compare existing frameworks and meta models and as a groundwork for engineering new ISD methods, and parts thereof. IGI PU…

The Early Years Home Learning Environment – Associations With Parent-Child-Course Attendance and Children’s Vocabulary at Age 3

2020

Although many studies investigated the effects of the home learning environment (HLE) in the preschool years, the constructs that underlie the HLE in the years before the age of three and its effects on language development are still poorly understood. This study therefore investigated the dimensionality of the HLE at age two, its relation to the attendance of low threshold parent-child-courses, and its importance for children's vocabulary development between age 2 and 3 years against the background of differing family background characteristics. Using data from 1,013 children and their families of the Newborn Cohort of the German National Educational Panel Study, structural equation modeli…

Numerical Analysis of Word Frequencies in Artificial and Natural Language Texts

1997

We perform a numerical study of the statistical properties of natural texts written in English and of two types of artificial texts. As statistical tools we use the conventional Zipf analysis of the distribution of words and the inverse Zipf analysis of the distribution of frequencies of words, the analysis of vocabulary growth, the Shannon entropy and a quantity which is a nonlinear function of frequencies of words, the frequency "entropy". Our numerical results, obtained by investigation of eight complete books and sixteen related artificial texts, suggest that, among these analyses, the analysis of vocabulary growth shows the most striking difference between natural and artificial texts…