Classification of ductile cast iron specimens: A machine learning approach

In this paper an automatic procedure based on a machine learning approach is proposed to classify ductile cast iron specimens according to the American Society for Testing and Materials guidelines. The mechanical properties of a specimen are strongly influenced by the peculiar morphology of their graphite elements and useful characteristics, the features, are extracted from the specimens’ images; these characteristics examine the shape, the distribution and the size of the graphite particle in the specimen, the nodularity and the nodule count. The principal components analysis are used to provide a more efficient representation of these data. Support vector machines are trained to obtain a classification of the data by yielding sequential binary classification steps. Numerical analysis is performed on a significant number of images providing robust results, also in presence of dust, scratches and measurement noise

Consumption, House Prices and Collateral Constraints: a Structural Econometric Analysis

If borrowing capacity of indebted households is tied to the value of their home, house prices should enter a correctly specified aggregate Euler equation for consumption. I develop a simple two-agent, dynamic general equilibrium model in which home (collateral) values affect debt capacity and consumption possibilities for a fraction of the households. I then derive and estimate an aggregate consumption Euler equation, and estimate its structural parameters. The results provide robust support for housing prices as a driving force of consumption fluctuations.Housing, consumption, collateral constraints

Household Debt and Income Inequality, 1963-2003

I construct a heterogeneous agents economy that mimics the time-series behavior of the US earnings distribution from 1963 to 2003. Agents face aggregate and idiosyncratic shocks and accumulate real and financial assets. I estimate the shocks driving the model using data on income inequality, on aggregate income and on measures of financial liberalization. I show how the model economy can replicate two empirical facts: the trend and cyclical behavior of household debt, and the diverging patterns in consumption and wealth inequality over time. In particular, I show that, while short-run changes in household debt can be accounted for by aggregate fluctuations, the rise in household debt of the 1980s and the 1990s can be quantitatively explained only by the concurrent increase in income inequalityHousehold Debt, Income Inequality, Incomplete Markets, Borrowing Constraints

House prices and the macroeconomy in Europe: Results from a structural var analysis

A structural vector autoregressive (SVAR) approach is used to identify the forces driving house prices fluctuations in France, Germany, Italy, Spain, Sweden and the UK over the period 1970-1998. Quarterly time series for real house prices, GDP, money, inflation and interest rates are characterised by a multivariate process driven by supply, nominal, monetary, inflationary and demand shocks. It is found that: (1) tight money leads to a concomitant fall in house prices and GDP; (2) the house price responses to a monetary shock can be partly justified by the different housing and financial market institutions across countries; (3) monetary and demand shocks drive most of the short-run house price volatility. The paper also interprets the main house price cycles and their links with the real economy in light of the estimates shocks. JEL Classification: C32, E32, E52, R21

Private Debt and Idiosyncratic Volatility: A Business Cycle Analysis

Debt, durables, volatility, borrowing constraints, housing

Optimal Control to Limit the Propagation Effect of a Virus Outbreak on a Network

The aim of this paper is to propose an optimal control strategy to face the propagation effects of a virus outbreak on a network; a recently proposed model is integrated and analysed. Depending on the specific model caracteristics, the epidemic spread could be more or less dangerous leading to a virus free or to a virus equilibrium. Two possible controls are introduced: a test on the computers connected in a network and the antivirus. In a condition of limited resources the best allocation strategy should allow to reduce the spread of the virus as soon as possible

State Feedback Optimal Control with Singular Solution for a Class of Nonlinear Dynamics

The paper studies the problem of determining the optimal control when singular arcs are present in the solution. In the general classical approach the expressions obtained depend on the state and the costate variables at the same time, so requiring a forward-backward integration for the computation of the control. In this paper, sufficient conditions on the dynamics structure are provided and discussed in order to have both the control and the switching function depending on the state only, so simplifying the computation avoiding the necessity of the backward integration. The approach has been validated on a classical SIR epidemic model

Analysis, Simulation and Control of a New Measles Epidemic Model

In this paper the problem of modeling and controlling the measles epidemic spread is faced. A new model is proposed and analysed; besides the categories usually considered in measles modeling, the susceptible, the exposed, the infected, the removed and, less frequently, the quarantine individuals, two new categories are herein introduced: the immunosuppressed subjects, that can not be vaccinated, and the patients with an additional complication, not risky by itself but dangerous if caught togeter with the measles. These two novelties are taken into account in designing and scheduling suitably control actions such as vaccination, whenever possible, prevention, quarantine and treatment, when limited resources are available. An analysis of the model is developed and the optimal control strategies are compared with other not optimized actions. By using the Pontryagin principle, it is shown the prevailing role of the vaccination in guaranteeing the protection to immunosuppressed individuals, as well as the importance of a prompt response of the society when an epidemic spread occurs, such as the quarantine intervention

The Credit Channel of Monetary Policy and Housing Markets: International Empirical Evidence

This paper tests for the presence of a credit channel (particularly a bank-lending sub-channel) for monetary policy in the housing market. We argue that the importance of this channel for investment in residential housing is highly dependent on the structural features, and particularly the efficiency and institutional organization, of housing finance. We employ a VAR methodology to analyse this issue with respect to the housing markets of four European countries (Finland, Germany, Norway and the United Kingdom), which differ greatly in terms of structural features. Our results are generally consistent with the existence of a broad credit channel, whereas the bank-lending channel seems to be operational only under certain conditions. More importantly, our results are consistent with previous analyses of housing market efficiency, which strongly suggests the existence of a clear relationship between the presence of a credit (bank lending) channel, the efficiency level of housing finance, and the type of institutions that are active in mortgage provision.monetary transmission; bank lending channel; house prices; vector autoregressions

An Improvement in a Local Observer Design for Optimal State Feedback Control: The Case Study of HIV/AIDS Diffusion

The paper addresses the problem of an observer design for a nonlinear system for which a preliminary linear state feedback is designed but the full state is not measurable. Since a linear control assures the fulfilment of local approximated conditions, usually a linear observer is designed in these cases to estimate the state with estimation error locally convergent to zero. The case in which the control contains an external reference, like in regulations problems, is studied, showing that the solution obtained working with the linear approximation to get local solutions produces non consistent results in terms of local regions of convergence for the system and for the observer. A solution to this problem is provided, proposing a different choice for the observer design which allows to obtain all conditions locally satisfied on the same local region in the neighbourhood of a new equilibrium point. The case study of an epidemic spread control is used to show the effectiveness of the procedure. The linear control with regulation term is present in this case because the problem is reconducted to a Linear Quadratic Regulation problem. Simulation results show the differences between the two approaches and the effectiveness of the proposed on