5,171 research outputs found
Child labor, school attendance and access to health care services by children: evidence from Ghana
The paper develops a simple two-period model relating child labor, child school attendance and child health care access in LDCs showing that child labor is positively correlated to access to health care services. In fact, higher medical expenditure generates better health and, therefore, higher child productivity. Accumulation of human capital, which generates higher future utility, comes at the expense of current productivity and consumption. The optimal choice of child labor is such that the marginal benefit of schooling is equal to the marginal productivity of child labor, which is enhanced by additional medical expenditure. Under this theoretical set-up we expect medical expenditure and child labor to be positively correlated, with parents caring more for their children if they contribute to household income. We explore these relationships using a micro data set from Ghana LSS for the year 1999. Empirical results confirm the model theoretical predictions.Child labor; Health care demand; Human capital; Latent variables; multivariate Probit; Unobserved heterogeneity; LDCs
Progettazione e Analisi di Dispositivi di Riscaldamento Attivo per Ridurre le Emissioni Inquinanti da Avviamento a Freddo di Motori a Combustione interna a Benzina
La crescente preoccupazione ambientale in molti paesi del mondo, ha spinto le istituzioni a introdurre legislazioni sempre piuÌ restrittive sulle emissioni inquinanti nel settore automobilistico. CioÌ ha portato a una progressiva revisione dei limiti sulle emissioni e, allo stesso tempo, delle procedure di test.
L'ottimizzazione della combustione del motore, sebbene fondamentale per ridurre le emissioni in uscita dal motore, non eÌ sufficiente per rispettare tali limiti; sono necessarie efficienze di conversione molto elevate da parte dei dispositivi di post-trattamento dei gas di scarico fin dall'avvio del motore.
La ricerca condotta in questo studio, riguarda la definizione e lâanalisi di dispositivi di riscaldamento attivo, per migliorare le prestazioni dei sistemi di post-trattamento dei gas di scarico, in particolare durante la fase critica di avviamento a freddo. Questa fase eÌ essenziale per il controllo delle emissioni, difatti, l'efficienza del sistema di post-trattamento si riduce significativamente quando il motore e il sistema di scarico sono freddi. Lo studio si eÌ concentrato su due tecnologie principali: il bruciatore di combustibile e il catalizzatore riscaldato elettricamente (EHC), entrambi testati e analizzati attraverso una combinazione di simulazioni numeriche e test sperimentali.
Il bruciatore di combustibile, un dispositivo progettato per introdurre una fiamma controllata direttamente allâinterno della linea di scarico (al fine di aumentare rapidamente la temperatura del post-trattamento), eÌ stato in una prima fase valutato attraverso simulazioni numeriche. Queste simulazioni (condotte in ambiente sia 1D che 3D) sono servite per prevedere il comportamento del bruciatore in diverse condizioni di utilizzo. La geometria della connessione tra il bruciatore e la linea di scarico eÌ stata anchâessa ottimizzata mediante simulazioni per garantire un efficiente trasferimento di calore dal bruciatore al post-trattamento dei gas di scarico.
Inoltre, le simulazioni hanno permesso di investigare gli effetti della variazione della durata del preriscaldamento (quanto tempo il bruciatore eÌ in funzione prima dell'avvio del motore) sulle emissioni allo scarico
Per validare queste simulazioni, sono state condotte prove sperimentali su un prototipo di bruciatore. Il funzionamento del bruciatore eÌ stato ottimizzato per ottenere un avviamento ripetibile, minimizzare le emissioni durante il funzionamento del bruciatore stesso (emissioni del bruciatore) e massimizzare l'output termico diretto verso il post-trattamento.
I risultati di questi esperimenti hanno dimostrato che il bruciatore puoÌ ridurre significativamente le emissioni allo scarico rispetto a strategie di riscaldamento passivo.
Parallelamente all'indagine sul bruciatore, la ricerca si eÌ concentrata anche sull'EHC, che utilizza energia elettrica per riscaldare il post-trattamento dei gas di scarico.
Analogamente al bruciatore, l'EHC eÌ stato valutato mediante simulazioni CFD sia 1D che 3D. Queste simulazioni hanno permesso di prevedere quanto efficacemente l'EHC po aumentare la temperatura del sistema di post-trattamento fino ad arrivare alla sua temperatura di attivazione. I modelli hanno preso in considerazione vari fattori, come ad esempio l'energia e la potenza elettrica impiegate.
A seguito delle simulazioni, eÌ stata condotta una campagna sperimentale dedicata. Gli esperimenti hanno convalidato l'accuratezza dei modelli di simulazione e hanno fornito dati reali sulle prestazioni dell'EHC.
Inoltre, sono state studiate diverse strategie di preriscaldamento per l'EHC, analizzando come l'attivazione del dispositivo prima dell'avvio del motore influenzasse l'efficienza complessiva del sistema di post-trattamento.
La ricerca ha dimostrato che l'EHC puoÌ migliorare la conversione degli inquinanti durante le fasi iniziali di avviamento a freddo, superando in efficacia le strategie di riscaldamento passivo del catalizzatore.In the last two decades, the increasing environmental concern in many countries worldwide has pushed the regulators to introduce more and more restrictive legislation on pollutant emissions for the automotive sector. This has led to a progressive revision of the emission limits and, at the same time, of the testing procedures.
Under these challenging boundary conditions, engine combustion optimization, although fundamental to lower specific engine-out emissions, is not enough; very high after-treatment conversion efficiencies from the engine start-up onwards are necessary.
The research undertaken in this work was a systematic exploration of the potential of active heating devices to improve the performance of exhaust after-treatment systems, particularly during the critical light-off phase. This phase is essential for emissions control, as the efficiency of the after-treatment system is significantly reduced when the engine and exhaust system are cold. The study focused on two main technologies: the fuel burner and the electrically heated catalyst (EHC), both of which were tested and analyzed through a combination of numerical simulations and experimental validation.
The fuel burner, a device designed to introduce a controlled flame directly into the exhaust line to rapidly increase the after-treatment temperature, was first assessed through numerical simulations. These simulations were crucial in predicting how the burner would perform under various conditions and were conducted in both 1D and 3D CFD configurations to provide a comprehensive understanding of its operation. The geometry of the connection between the burner and the exhaust line was also optimized by means of simulations to ensure efficient heat transfer and minimal heat loss.
Moreover, the simulations allowed to investigate the effects of varying the pre-heating duration (how long the burner operated before the engine was started) on the tail pipe emissions output.
To validate these simulations, experimental trials were conducted on a prototype fuel burner. The fuel burner operation was optimized to achieve a repeatable start-up, to minimize emissions during the burner operation (burner-out emissions), and to maximize the thermal output.
The results from these experiments were crucial, demonstrating that the fuel burner could significantly reduce the cumulative tailpipe emissions when compared to passive heating strategies.
Parallel to the fuel burner investigation, the research also concentrated on the EHC, which uses electrical energy to heat the after-treatment.
Similar to the fuel burner, the EHC was evaluated using both 1D and 3D CFD simulations. These simulations were designed to predict how effectively the EHC could raise the temperature of the after-treatment system to its light-off temperature. The models took into account various factors, such as the electrical energy and power input, and the heat transfer characteristics of the after-treatment system.
Following the simulations, a dedicated experimental campaign took place. The experiments were critical for two main reasons: they validated the accuracy of the simulation models and provided real-world data on the performance of the EHC.
Moreover, pre-heating strategies for the EHC were investigated, analyzing how activating the device before the engine start-up affected the overall efficiency of the after-treatment system.
The research demonstrated that EHC could improve the conversion of pollutants during the initial cold start phases, outperforming passive catalyst heating strategies.
The comparative analysis between the fuel burner and the EHC highlighted that both technologies could significantly reduce cumulative tailpipe gaseous emissions during engine cold starts
Memory for prices and the euro cash changeover: An analysis for cinema prices in Italy
The question addressed by this study is whether consumers remember past prices correctly. We test Italian citizensĂâ memory for cinema prices with questionnaires distributed to moviegoers. The analysis concentrates on the memory of pre-euro prices, but the recall for a more recent period is also investigated. The results show that only a small percentage of respondents recalled the correct price, and that the average prices recalled were much lower than the actual pre-euro prices and dated back to years before the changeover. Price recall is less accurate for the respondents who perceive higher and more persistent inflation; it is also worse for the older respondents and for the less frequent movie-goers.prices, memory, perceptions, euro
A New Real Time Shape Acquisition with a Laser Scanner: First Test Results
Abstract
The first results of a new method for real-time shape acquisition with a laser scanner are presented. The new method is essentially based on the use of a laser beam and a web-cam. A digital filter parameters identification was studied for the laser line detection in the image. After this, a model for the reconstruction in real-time of the laser line in the space was developed. The firsttest rig was just conceived to validate the method; hence, no high resolution cameras were adopted. Nevertheless, the tests have showed encouraging results.
Tests were made on both plane and non-plane surfaces. First of all, it was confirmed that it is possible to calibrate the intrinsic parameters of the video system, the position of the image plane and the laser plane in a given frame, all in the same time. Moreover the surface shapes were recognized and recorded with an appreciable accuracy. The tests also showed that the proposed method can be used for robotic applications, such as robotic kinematic calibration and 3D surfaces recognition and recording. For this last purpose, the test rig is fitted on a robot arm that permits to the scanner device to âobserveâ the 3D object from different and known positions
Memory for symmetry and perceptual binding in patients with schizophrenia
The present study investigated the use of perceptual binding processes in schizophrenic (SC) patients and matched healthy controls, by examining their performance on the recall of symmetrical (vertical, horizontal and diagonal) and asymmetrical patterns varying in length between 2 and 9 items. The results showed that, although SC patients were less accurate than controls in all conditions, both groups recalled symmetrical patterns better than asymmetrical ones. The impairment of SC patients was magnified with supra-span symmetrical arrays, and they were more likely to reproduce symmetrical patterns as asymmetrical, particularly at medium and high length levels. Hierarchical regression analyses further indicated that the between-group differences in the recall of supra-span vertical and horizontal arrays, which require a greater involvement of visual pattern processes, remained significant after removing the variance associated with performance on asymmetrical patterns, which primarily reflects intrafigural spatial processes. It is proposed that schizophrenia may be associated with a specific deficit in the formation and retrieval of the global visual images of studied patterns and in the use of the on-line information about the type of symmetry being tested to guide retrieval processes. © 2013 Elsevier B.V
Robot Assisted 3D Shape Acquisition Optical Systems
In this chapter, a short description of the basic concepts about optical methods for the
acquisition of three-dimensional shapes is first presented. Then two applications of the
surface reconstruction are presented: the passive technique Shape from Silhouettes and the
active technique Laser Triangolation. With both these techniques the sensors (telecameras
and laser beam) were moved and oriented by means of a robot arm. In fact, for complex
objects, it is important that the measuring device can move along arbitrary paths and make
its measurements from suitable directions. This chapter shows how a standard industrial
robot with a laser profile scanner can be used to achieve the desired d-o-f.
Finally some experimental results of shape acquisition by means of the Laser Triangolation
technique are reported
Precautionary saving and health risk evidence from the Italian households using a time series of cross sections
In this paper we analyse the importance of precautionary saving in Italy. In contrast to previous studies, we focus on two contemporaneous sources of uncertainty, income and health expenditures, to explain the presence of precautionary saving. The major changes occurred in public health care policies from 1985 to 1996 have caused households to pay a larger share of their out-of-the-pocket medical expenditures. These
events have caused households to face both a higher expected mean and a larger variance of health expenditures. Moreover, the economic recession occurred in the early â90s and the Maastricht requirements led to general worsening of future expectations of income. We therefore expect consumers to react to this uncertainty by generating precautionary saving. We test this prediction using an Euler equation augmented with the presence of the variance of income and health expenditure shocks. By using a time series of cross sections from the ISTAT household budget survey, we find strong support for
precautionary saving as a response to health uncertainty
How the Energy Price Variability in Italy Affects the Cost of Building Heating: A Trnsys-Guided Comparison between Air-Source Heat Pumps and Gas Boilers
The paper investigates the variation in building thermal energy demand for different
indoor air set-point temperature and presents an economic analysis comparing the cost of a heating generation system based on an air-to-water heat pump and a gas boiler. Dynamic simulations were performed considering three different residential building characteristics of the Italian building stock placed in different Italian municipalities: Milan, Rome and Naples. An economic analysis was carried
out considering the gas and electricity prices related to the years 2019â2022 provided by Italian Regulatory Authority for Energy, Networks and Environment (ARERA). The analysis showed the competitiveness of the heat pump compared with the gas boiler as a heating generation system in terms of annual costs for heating in almost all the scenarios considered and also showed an important reduction in building thermal energy demand if the set-point temperature was reduced, even by 1 âŠC
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