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The Design of Voluntary Agreements in Oligopolistic Markets
Get PDFThis paper analyses the conditions under which a group of firms is incentivised to sign a voluntary agreement (VA) to control polluting emissions even in the presence of free-riding by other firms in the industry. We consider a policy framework in which firms in a given industry decide whether or not to sign a VA proposed by an environmental regulator. We identify the features that a VA should possess in order to incentivize firms to participate in the VA and to enhance its economic and environmental effectiveness. Under very general conditions on the shape of the demand schedule, we obtain the following results. First, a VA does not belong to the equilibrium of the coalition game when benefits from voluntary emission abatement are a pure public good. Second, in the presence of partial spillovers – i.e. when signatories obtain more benefits from the VA than non-signatories – a VA belongs to the equilibrium only if a minimum participation rule is guaranteed. Third, a VA with a minimum participation rule and a minimum mandatory emission abatement may improve welfare (and even industry profits) compared to a VA in which firms are free to set their own profit maximising abatement level
Alcune note sulla geografia umana della Provincia Sardinia
Get PDFAbstract - The recent discovery of some epigraphic artefacts in the countryside of Barumini and Siddi (Sardinia, Italy) is an opportunity to reflect on the Romanization of Sardinia. The new interpretation of CIL X, 7840 from Vallermosa, where the Fifenses are mentioned, and the identification of a new populus, the Barsanes (vel Barsani), allow us to put forward the proposal of a new cartography of Roman Sardinia. The epitaph of a colonus suggests an opportunity of going deeply into the question of Marmilla agrarian organization in the Roman age
---- [ITALIANO] Sommario - Il recente rinvenimento di alcuni manufatti epigrafici in agro di Siddi e Barumini sono l’occasione per una riflessione sulla romanizzazione della Sardegna. La rilettura di CIL X, 7840 da Vallermosa in cui vengono menzionati i Fifenses e l’individuazione di un nuovo populus, i Barsanes (vel Barsani) consentono di poter avanzare la proposta di una nuova cartografia su cui discutere. L’iscrizione di un colonus suggerisce lo spunto per un approfondimento dell’organizzazione agraria della Marmilla in età romana
Interazione dopamina-ossitocina nel controllo centrale della risposta erettile
No full textWe investigated: 1) the effect of a pro-erectile dose of apomorphine, a mixed dopamine receptor agonist, injected into the PVN on the release of dopamine by mesolimbic dopaminergic neurons in the “shell” of the nucleus accumbens; 2) the effect of oxytocin injected into the VTA on penile erection and on the concentration of dopamine into the “shell” of the nucleus accumbens and into the PVN; 3) the mechanism responsible for the pro-erectile effect of oxytocin injection into the VTA, mainly the role of the NO-GMPc system; and 4) the relationship between oxytocinergic fibers/axons, mesolimbic dopaminergic cell bodies, NO synthase and guanylyl cyclase into the VTA.
The results obtained suggest the existence of a neural circuit where dopaminergic and oxytocinergic neurons play a key role in the motivational/rewarding and consummatory aspects of male sexual behavior. When activated, this circuit facilitates not only the copulatory behavior through the activation of paraventricular oxytocinergic neurons projecting to the spinal cord, but also the mechanisms controlling sexual motivation and sexual reward through the activation of paraventricular oxytocinergic neurons projecting to the VTA. Infact, oxytocin released here activates the NO-cGMP system localized into the cell bodies of the mesolimbic dopaminergic neurons and this, in turn, lead to the release of dopamine into the nucleus accumbens.
This neural circuit may play a key role in the integration of the activity of neural pathways controlling the consummatory (erection-ejaculation) and anticipatory (motivation and reward) aspects of the male sexual behavior in physiological contexts
Simulation of delamination in composite materials under static and fatigue loading by cohesive zone models
Get PDFThis thesis is a dissertation focusing on the mechanics of delamination in laminated composites. Delamination, one of the most critical forms of failure in composite materials, may occur as a result of many causes and different types of loading, such as, for example, static or cyclic loading.
This work presents an examination of the potential of cohesive interface elements for the prediction of delamination propagation under quasi-static mode I, mode II and mixed mode (I and II) loading, by a comparison between experimental tests and parametric analyses in order to evaluate the sensitivity of the elements to some parameters. The results of the comparison show that a rather good accordance may be obtained between experimental data and numerical simulations with a proper choice of the main model parameters.
Moreover, a simplified mathematical model for the study of fatigue driven delamination is described. This model is particularly useful for investigating the performance of various formulations of interface elements that are used to simulate delamination under cyclic loading, because of its simplicity and efficiency that allow evaluating a large number of sets of parameter values. The model has been studied with different static constitutive laws and damage definitions, coupled with a particular fatigue degradation strategy. In particular, the sensitivity of the model, with the different proposed constitutive laws, has been evaluated with respect to some its key parameters
They arrive with new information. Tourism flows and production efficiency in the European regions
Get PDFIt is well known that firms productivity is influenced by information spillovers
generated either by other firms located nearby or by direct contacts with final
demand or by foreign demand in the case of traded products.
In this paper we investigate a new channel of efficiency - enhancing information
spillovers: tourism flows. The idea is that tourists, in general, have preferences for
high quality goods and differentiated products which are revealed when they buy
local products in the tourism destinations, thus transmitting relevant information to
the local firms. The latter, in turn, exploit this new information generating a positive
impact on the efficiency level of the local economy.
More specifically we examine the effects of tourist flows on regional total factor
productivity, within a spatial dynamic model, controlling also for other intangible
factors (such as human, social and technological capital) and for the degree of
accessibility. We apply the analysis to 199 European regions belonging to the EU15
member countries, plus Switzerland and Norway.
The econometric results show the positive impact of tourism flows on regional
efficiency levels together with the positive role played by intangible assets,
infrastructures and spatial spillovers
Innovazione unica direzione.
Get PDFLe attività della Direzione
per le Relazioni con il territorio, l'innovazione e lo sviluppo
Predictive control of electrical drives
Get PDFIn this work, the application of the Predictive Control Technique to the electrical drives has been considered and discussed, especially in comparison with the employment of the traditional control techniques. First of all, a predictive control algorithm for the Brushless DC drive is developed with the aim of improving the traditional current commutation as best as possible. Then, a novel predictive control algorithm is proposed by imposing both the reference torque value and the minimum Joule losses condition. Then, several predictive control algorithms are proposed for the Synchronous Reluctance Machine, taking into account the magnetic saturation effects too. They are based either on the traditional control strategy or on optimization criteria, such as the minimum steady state Joule losses condition and the fastest achievement of the reference torque value. Finally, a novel predictive Direct Torque Control algorithm is synthesized for the Asynchronous Machine, by taking into account both voltage saturation and current limitation constraints. The synthesizing procedure adopted is also shown by an interesting graphical representation. The effectiveness of all the proposed algorithms has been properly tested by appropriate simulation studies, performed in the Matlab Simulink environment. The corresponding results have highlighted how the employment of the Predictive Control Technique allows better performances compared to those achievable by the traditional control ones
Donne, informatica ed esclusione. Apprendimento dell'informatica e performance di genere in Sardegna
Get PDFThe main topic of this essay is the articulation of standardized computing applications in several women groups in North Sardinia. The analysis focuses on the translation of technical devices, the place of women in computing and roles of socialization, imitation, learning and membership in this process. The analysis shows the relevance and the difference of the technological ecologies, and the role played by emotions such as the fear of the computer in disciplining marginality of women. This fear, especially among young women, naturalizes their lack of involvement in computing worlds, but can be explained analyzing the ways the technological systems and gender are performed
New design methodologies for microwave oscillators based on negative impedance. Study and development of the solution space concept
Get PDFThe topic of this thesis concern the study of new design methodologies for microwave oscillators based on negative impedance and LC resonant circuits.
For this class of systems, it is not ordinary possibile to predict the stationary behaviour of the circuit without use non linear analysis methodologies, but these are very e complicated and not very helpful for the design. Indeed, for microwave circuits, the design technique is that of reflection parameters "S" that describe with accuracy only linear systems and shaped them in response to small signal conditions.
Therefore the only way to design a good oscillator is through experience and try and error procedures.
By Developping a CAD tool that allows to represent in graphical form all possibile solutions (The Solution Space) for which an amplifier and two passive networks (feedback and loads) are able to give a negative impedance looking by other port, a new design methodology has been presented.
This methodology use only S small signal parameters and allows to guarantee the start-up for a given frequency when the other port is colsed with a proper LC circuit, and moreover is able to predict the behaviour of the system in steady state. Then became easily possibile to design the system in order to maximize the output power and reduce the phase noise.
The proposed methodology is then successfully used in the design of a 38GHz VCO. ------------------------------------------------------------------------------------------------------------------------
L’oggetto di questa tesi è lo studio di nuove metodologie di progetto per oscillatori a microonde costituiti da un blocco di impedenza negativa e un circuito risonante LC.
Per tale classe di sistemi la difficoltà nella procedura di progettazione consiste nel non aver ancora trovato una chiave che permettesse di prevederne il comportamento a regime senza l’utilizzo di metodi di analisi non lineare, notoriamente molto complicati e poco utili per il progetto. Infatti, per i circuiti a microonde, la tecnica universalmente adottata è quella dell’utilizzo dei parametri di riflessione “S” che descrivono con veridicità solamente sistemi lineari e modellati in risposta a condizioni di piccolo segnale.
Non esistono quindi metodologie per gli oscillatori che vengono progettati secondo esperienza procedure del tipo try and error.
Sviluppando al calcolatore un tool che permette la rappresentazione grafica dell’insieme delle soluzioni (Spazio delle Soluzioni) per cui un sistema costituito da amplificatore e reti passive di reazione e di carico possono generare una resistenza negativa ad una porta si è messa appunto una metodologia che non solo garantisce le condizioni di innesco del sistema quando la restante porta viene chiusa da un opportuno circuito risonante, di cui è possibile estrarre le caratteristiche, ma anche di prevedere unicamente utilizzando i parametri a piccolo segnale, il comportamento del sistema a largo segnale e di progettare l’oscillatore in maniera scientifica secondo le specifiche desiderate. La metodologia proposta viene quindi applicata con successo al progetto di un VCO a 38GHz
Essays in New Economic Geography
Get PDFThe recent Nobel Prize assigned to Paul Krugman "for his analysis of trade patterns and location of economic activity" witnesses the important role that the scienti�c community gives to the insights of the so-called New Economic Geography (NEG) literature. This field of economic analysis has always been particularly appealing to policy makers, given the direct link between its results
and regional policy rules. For the same reason it is useful to deepen the analysis of its most important outputs by testing the theoretical robustness of some of
its more relevant statements. This thesis tries to o¤er a contribution in this direction by focusing on a particular sub-field of NEG literature, the so-called
New Economic Geography and Growth (NEGG) literature, having in Baldwin and Martin (2004) and Baldwin et. al (2004) the most important theoretical syntheses. These two surveys collect and present in an uni�ed framework the
works by Baldwin, Martin and Ottaviano (2001), where capital is immobile and spillovers are localized, Martin and Ottaviano (1999) where spillovers are global
and capital is mobile. Other related papers are Baldwin (1999) which introduces forward looking expectations in the so-called Footloose capital model developed
by Martin and Rogers (1995); Baldwin and Forslid (1999) which introduces endogenous growth by means of a q-theory approach; Baldwin and Forslid (2000)
where spillovers are localized, capital is immobile and migration is allowed.
Some more recent developments in the NEGG literature can be distinguished in two main strands. One takes into consideration factor price differences in
order to discuss the possibility of a monotonic relation between agglomeration and integration (Bellone and Maupertuis (2003) and Andres (2007)). The other
one assumes firms heterogeneity in productivity (first introduced by Eaton and Kortum (2002) and Melitz (2003)) in order to analyse the relationship between
growth and the spatial selection e¤ect leading the most productive firms to move to larger markets (see Baldwin and Okubo (2006) and Baldwin and Robert-Nicoud (2008). These recent developments are related to our work in introducing some relevant departures from the standard model. Indeed this thesis develops
and extends the theoretical framework of New Economic Geography theory along several routes.
In the third chapter of the thesis we develop a New Economic Geography and Growth model which, by using a CES utility function in the second-stage
optimization problem, allows for expenditure shares in industrial goods to be endogenously determined. The implications of our generalization are quite rel-evant. In particular, we obtain the following novel results: 1) catastrophic
agglomeration may always take place, whatever the degree of market integration, provided that the traditional and the industrial goods are su¢ ciently good
substitutes; 2) the regional rate of growth is affected by the interregional allocation of economic activities even in the absence of localized spillovers, so that
geography always matters for growth and 3) the regional rate of growth is af-
fected by the degree of market openness: in particular, depending on whether
the traditional and the industrial goods are good or poor substitutes, economic
integration may be respectively growth-enhancing or growth-detrimental.
In the fourth chapter of the thesis we build a New Economic Geography
and Growth model based on Baldwin, Martin and Ottaviano (2001) with an
additional sector producing Non-tradable goods (services). By assuming intersectoral and localized knowledge spillovers from the innovation sector to the
service sector, we show that firms'allocation affects regional real growth. More
precisely we assume that the unit labour requirements (and thereby the prices)
in the service production are a negative function of the output of innovation, i.e.
the stock of knowledge capital. Due to this new specification, real growth rates
in the two regions always diverge when the firms allocation pattern differs from
the symmetric one. This result is a novelty in the standard theoretical NEGG literature where regional gap in real growth rate is always zero. Moreover, this result has strong policy implications because it suggests that concentrating in-
dustries in only one region may also bring a dynamic loss for the periphery.
By analyzing the trade-o¤ between the dynamic gains of agglomeration (due to localized intertemporal spillovers) and the dynamic loss of agglomeration (due to localized intersectoral spillovers), we also discuss different notions of optimal
level of agglomeration.
The thesis will proceed as follows: in the chapters one and two we describe the state of the art in New Economic Geography and its further developments such as the New Economic Geography and Growth, the possibility of a monotonic relation between agglomeration and integration, and finally the firms heterogeneity in New Economic Geography models. Instead in chapters
three and four we present our original contribution to the theory, i.e. the analysis of endogenous expenditure shares and intersectoral knowledge spillovers on the agglomeration patterns and economic growth