Is the Discouraged Worker Effect Time-Varying?

This study investigates the relationship between the female labour force participation and the female employment rate in Italy by adopting non-linear econometric modelling. In our specification we are unable to reject a nonlinear relationship. This implies that the discouraged worker effect is timevarying.Discouraged Workers, Non-linearity

ON THE NON-LINEAR DYNAMICS BETWEEN EMPLOYMENT AND LABOUR FORCE PARTICIPATION

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Designing the Optimal Length of Working Time

How many hours per week should workers in the United States and Germany spend at their paying jobs? The present paper addresses this question by constructing policymakers’ reaction functions capable of modelling the optimal length of working time as a function of the relevant labour market variables. The empirical analysis is based on the optimal control algorithm. Given a policymaker’s loss function and a structural model of the labour market we define alternative specifications of reaction functions where the response coefficients indicate how policymakers should react to any news in the labour market in order to stabilize employment and wages. We also perform a comparative analysis on the ability of the rules to correspond to historical working-time records. The results suggest that simple rules perform quite well and that the advantages obtained from adopting an optimal control-based rule are not so great. Moreover, the analysis emphasizes the success of the wage-based rule and of the employment based rule in the US and Germany, respectively. Finally, we propose a policy rule to capture the dynamics of the weekly working hours. According to our rule the length of the workweek is an inverse function of the deviation between the actual and potential employment level.Policy Rule, Working-time, Dynamic Optimization

Processing and characterization of layered UHTCMCs reinforced with continuous or discontinuous carbon fibers

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ORARIO DI LAVORO E OCCUPAZIONE IN UN CONTESTO ECONOMICO BISETTORIALE

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EMPLOYMENT, CAPITAL OPERATING TIME AND EFFICIENCY WAGES HYPOTHESIS: IS THERE ANY ROOM FOR WORKSHARING?

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Influence of SiC on the oxidation resistance of carbon fibre reinforced UHTCMCsAntonio Vinci

Ultra-High-Temperature-Ceramics (UHTCs) are a novel class of refractory materials characterized by melting points exceeding 3000°C and very good thermo-mechanical properties [1]. In particular, ZrB2 composites have been extensively investigated as potential candidates for the fabrication of reusable Thermal Protection Systems (TPS) for aerospace applications due to their relatively low density and high thermal conductivity. The main drawbacks are the low oxidation resistance of ZrB2 above 1000°C, due to the formation of a porous ZrO2 scale and evaporation of B2O3, and low fracture toughness. Silicon carbide has been found to increase its oxidation resistance up to 1650 owing to the formation of a protective, viscous borosilicate scale [2][3]. However, their low fracture toughness and thermal shock resistance remain major obstacles for their application [4][5]. For this purpose, continuous carbon fibres (~45 vol.%) were used as reinforcement in order to increase their fracture toughness and thermal shock resistance. The resulting materials were labeled “UHTCMCs” (Ultra High Temperature Ceramic Matrix Composites). In the present work, the oxidation resistance of carbon fibre reinforced ZrB2/SiC composites was studied. Composites with SiC amounts ranging from 5-20 vol.% were fabricated by slurry infiltration and hot pressing at 1900°C and 40 MPa. Oxidation tests were carried out on cut specimen (2 x 2.5 x 12 mm3) in a bottom-up loading furnace at 1500°C and 1650°C. The resulting microstructures were analysed by SEM-EDS and X-ray diffraction analysis. Weight loss per surface area was recorded after each test. Results show that the formation of a viscous borosilicate glass phase is essential for the protection of carbon fibres from oxidation; low amounts of SiC do not provide enough protection against fibre degradation, but with increasing the SiC amount there is an increase in the thickness of the protective layer and a decrease in weight loss. References [1] W.G. Fahrenholtz, G.E. Hilmas, I.G. Talmy, J.A. Zaykoski, Refractory diborides of zirconium and hafnium, J. Am. Ceram. Soc. 90 (2007) 1347–1364. doi:10.1111/j.1551-2916.2007.01583.x. [2] L. Zhang, K. Kurokawa, Effect of SiC Addition on Oxidation Behavior of ZrB2 at 1273??K and 1473??K, Oxid. Met. 85 (2016) 311–320. doi:10.1007/s11085-015-9585-9. [3] J. He, Y. Wang, L. Luo, L. An, Oxidation behaviour of ZrB2–SiC (Al/Y) ceramics at 1700°C, J. Eur. Ceram. Soc. (2016). doi:10.1016/j.jeurceramsoc.2016.02.037. [4] R. Zhang, X. Cheng, D. Fang, L. Ke, Y. Wang, Ultra-high-temperature tensile properties and fracture behavior of ZrB2-based ceramics in air above 1500??C, Mater. Des. 52 (2013) 17–22. doi:10.1016/j.matdes.2013.05.045. [5] E. Zapata-Solvas, D.D. Jayaseelan, H.T. Lin, P. Brown, W.E. Lee, Mechanical properties of ZrB2- and HfB2-based ultra-high temperature ceramics fabricated by spark plasma sintering, J. Eur. Ceram. Soc. 33 (2013) 1373–1386. doi:10.1016/j.jeurceramsoc.2012.12.009

CAPITALE UMANO, ORARIO DI LAVORO, SALARI DI EFFICIENZA E COT IN UN MODELLO DI SVILUPPO DUALISTICO

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Studio e progetto del circuito di polarizzazione in un sistema optoelettronico per misura distribuita di temperatura

La presente tesi è il resoconto di un lavoro sperimentale di progettazione di un circuito per il controllo e la polarizzazione di un fotorivelatore di tipo APD (avalanche photo diode). Il lavoro è stato realizzato nell'ambito di un progetto di un sistema optoelettronico per la misura distribuita di temperatura tramite tecniche di riflettometria ottica nel dominio del tempo. Come introduzione al progetto viene quindi illustrata la tecnica della riflettometria ottica nel dominio del tempo, la sua applicazione per la realizzazione di un sensore distribuito di temperatura, e la struttura generale del sistema elettronico. Vengono poi affrontate le problematiche progettuali specifiche per il circuito di polarizzaziome, riguardanti sia l'aspetto elettronico che quello software, queste ultime in stretta relazione con l'intero sistema elettronico di misura. Infine, sono riportati i risultati del collaudo e la caratterizzazione del circuito di polarizzazione

REDUCING WORKING TIME IN AN EFFICIENCY WAGE ECONOMY WITH A DUAL LABOUR MARKET

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