Search results for " Mathematica"
showing 10 items of 689 documents
Meaningful learning and new technologies: e-learning and mathematical surfaces
2014
E-learning is undoubtedly a unique and exciting opportunity for interaction between the traditional teaching-methodological framework and the new technologies. It gives the opportunity for each student to build their own personal path of interpretation and ease the reticulated structure of knowledge. The learning process assumes, in this way, a fundamental creative-ideational dimension. Multimedia and interactivity have, in fact, reason to exist and meaning in the cortical structure and in the reticular human thought. The media ducation (and e-learning in particular) lies then in a scenario in which human relationships and communication at all levels are no arbitrary situations, assigned to…
Urban segregation and unemployment: A case study of the urban area of Marseille – Aix-en-Provence (France)
2018
International audience; In this paper, we study the effects of the spatial organization of the urban area of Marseille – Aix-en-Provence on unemployment there. More specifically, differences in the characteristics of the residential population induce urban stratification with the result that urban structure may affect the probability of employment. In order to evaluate the effects of spatial structure on unemployment, we implement a spatial probit model to reveal the employment probabilities of young adults still living with their parents. Our results support the hypothesis that living in or near a deprived neighborhood decreases the probability of employment.
RENT CREATION AND RENT SHARING: NEW MEASURES AND IMPACTS ON TOTAL FACTOR PRODUCTIVITY
2019
International audience; This analysis proposes new measures of rent creation and rent sharing and assesses their impact on productivity on cross-country-industry panel data. We find first that: (1) anticompetitive product market regulations positively affect rent creation and (2) employment protection legislation boosts hourly wages, particularly for low-skill workers. However, we find no significant impact of this employment legislation on rent sharing, as the hourly wage increases are offset by a negative impact on hours worked. Second, using regulation indicators as instruments, we find that rent creation and rent sharing both have a substantial negative impact on total factor productivi…
"Facta non verba" : an experiment on pledging and giving
2015
International audience; We design an experiment to investigate whether asking people to state how much they will donate to a charity (i.e., to pledge) increases their actual donation. Individuals’ endowment is either certain or a random variable. We study different types of pledges, namely, private, public and irrevocable, which differ in terms of the cost to the individual for not keeping the promise. We show that in absence of endowment uncertainty, private and public pledges are associated with lower donations as compared to donations in the no-pledge case: private pledges slightly reduce donations and public pledges reduce them more significantly. Donations increase with uncertainty (in…
Environmental expenditure interactions among OECD countries, 1995-2017
2021
International audience; How do countries respond to other countries when setting the level of their environmental expenditures? Using data from 1995-2017 on a sample of 28 OECD countries, we examine the nature and extent of strategic interactions in environmental expenditures among OECD countries using a spatial Durbin model including economic and political control variables and both economic and spatial weight matrices reflecting several interaction mechanisms. The results show the existence of significant positive spatial dependence in environmental spending suggesting that OECD countries consider their neighbors' behavior when making policy choices related to environmental expenditures. …
Quantum Concepts in the Social, Ecological and Biological Sciences
2019
This is a book of applications of quantum techniques to modelization in various areas.
The renormalized electron mass in non-relativistic quantum electrodynamics
2007
This work addresses the problem of infrared mass renormalization for a scalar electron in a translation-invariant model of non-relativistic QED. We assume that the interaction of the electron with the quantized electromagnetic field comprises a fixed ultraviolet regularization and an infrared regularization parametrized by $\sigma>0$. For the value $p=0$ of the conserved total momentum of electron and photon field, bounds on the renormalized mass are established which are uniform in $\sigma\to0$, and the existence of a ground state is proved. For $|p|>0$ sufficiently small, bounds on the renormalized mass are derived for any fixed $\sigma>0$. A key ingredient of our proofs is the operator-t…
Experimental validation of a general model for three phase inverters operating in healthy and faulty modes
2012
The paper presents the experimental verification of a general mathematical model of Voltage Source Inverters (VSI) able to simulate fault conditions and which is also useful for the simulation of fault-tolerant systems for different applications. In general, in the past, the problem of faulty inverters modeling has been addressed specifically by considering faults on the different phases as separate cases. Furthermore, traditional models include only the faulty mode and not the healthy mode, so resulting then not able to predict transient phenomena. The model hereafter presented overcomes this drawback. It was formulated by introducing the concept of “healthy leg binary variables”. Such var…
Mathematical Model of a PM Brushless Motor with Different Stator-Rotor Pole Pairs Number
2013
The paper presents a mathematical model of Permanent Magnet AC brushless machines (PMSM) having a number of stator poles-obtained via the distribution of the three-phase winding- different from the rotor one, realized by the displacement of the permanent magnets. For these so- called ‘Fractional-Slot’ motors (where few total slots generate high equivalent number of poles) the available mathematical models appear partial and/or incomplete, despite of numerous designing considerations made in literature. In this paper an analytical approach is developed to point out an instantaneous- values mathematical model with concentrated parameters, that can be suitable for control architecture systems …
Optimum Performance of Permanent Magnet Synchronous Generators Coupled to Wind Turbines
2007
In this paper a control algorithm for the efficiency improvement of permanent magnet synchronous generators (PMSG) is presented. The proposed algorithm reduces the losses of the generator without affecting its performances. In details, after a description of a dynamic model of the PMSG, which has been purposely modified in order to take into account the iron losses, the basic equations and the constraints to obtain the loss minimization are presented and discussed. Some simulations of a specific PMSG employing the proposed algorithm are performed. The results of these simulations show that enhancement of the efficiency up to 3% can be reached in comparison to a PMSG using a traditional cont…