Suchergebnisse

The attitude of individuals towards saving, the motivations which lead people to save or not to save, the government-mandated pension and retirement policies have changed dramatically during the past decades. The purpose of this work is to give an in-depth look at these important policy issues and changes happened in four chapters. Chapter one provides some definitions of the main economic variables both at the micro and macro levels and a closer look at the current data on savings and on the complex range of public, private and voluntary retirement plans which are now playing a greater role in pension-provision in many OECD countries. Chapter two is devoted to the most significant theories about the origin and the effects of pension systems, in particular, the "Intertemporal choice model" by Irving Fisher, "The life cycle model" by Franco Modigliani and the "Permanent Income Theory" by Milton Friedman. Chapter three presents a consistent framework which describes the social security systems across OECD countries: replacement rates, financial schemes (Pay-As-You-Go and Fully Funded), contribution systems (defined contribution and defined benefit), the calculation of pension benefits, the effects of the social security system on individual decisions and the problems related to the transition from a Pay-As-You-Go to a Fully Funded program. Finally, chapter four attempts to develop a model whose purpose is to find the optimal mix between the Pay-As-You-Go and Fully Funded programs, and in the last section it also provides some numerical estimates related to the model. A description of the Italian pension system and the most significative steps of the long series of reforms that have affected the social security system in Italy in the last two decades are provided for in Appendix A.

China has the largest construction volume in the world with about 2 billion square meters of new buildings completed annually. Currently about 80% of these are categorized as high-energy buildings and more than 90% of new buildings are considered high life-cycle energy buildings. The speed of construction in China is amazing and it's stimulated even further by the fast rates of urbanization. In order to decrease energy consumption of buildings, there is a need for strong political will and implementation of strict building regulations. China is geographically a vast country and it's impossible to design a single building code for the whole country. Energy consumption per building in China is 2-3 times higher than that of the developed countries with similar climatic conditions, and buildings are less comfortable as a result of poor thermal performance and too little insulation in most of China's buildings. Although the Chinese government has issued many standards and codes in order to improve energy efficiency of buildings, little effect has appeared and less than 6% of newly constructed buildings comply with these standards. China is a large country with a complex climate that in the national standard (GB50176-93) it's divided into five climate zones. Because of the "Qin-Huai line", for severe cold and cold zones, they have central heating system while 14 provinces and nearly half of the population of China is living in the hot summer and cold winter zones (HSCW) where they don't have central heating system. This is the first reason why in these zones heat pump systems play a very important role in heating buildings. Air source heat pump (ASHP) as an optional product has already been widely applied in families and companies. This project reports a novel application of an air source heat pump system for cooling, heating and domestic hot water production in Shanghai for a typical apartment. In winter, the system was aim to solve the central heating problem. The system was combined with a Low-H_2O heat exchanger to decrease the supply water temperature in order to save energy. The heating return water temperature was set at 30 °C, 35 °C and 40 °C for heating in winter which is lower than the conventional air source heat pump system. This system composed by the ASHP and the STDFCU has been tested, from December to February, in an apartment, aiming to the energy saving and the user's comfort. We found, for each experiment, the values of heating capacity and energy consumption and we can say that the heat pump's power is always sufficient to heat the apartment except with the temperature at 40 °C and the internal temperature at 22°C. Moreover, the internal conditions are always good for the users with an internal temperature between 19 and 21 °C. The use of computer software can be useful to simulate the model and to compare results with the experimental's data. That's why we created a model of the whole system and simulated it on EnergyPlus, an energy analysis and thermal load simulation program. Starting with a simplified model, finally we simulated the apartment finding heating capacity of the same order of magnitude that in the experiments.

In the last decades a growing awareness emerged of the relevance of corruption as an hidden factor which may negatively affect political and economic decision-making processes. In spite of a lively scientific debate there is no general consensus on a commonly accepted definition of what corruption is. The A. distinguishes three main paradigms, focusing on different (though not irreconcilable) variables. The first is the economic paradigm, which usually takes the principal-agent model of corruption as its founding pillar. In this paradigm corruption is considered the outcome of rational individual choices, and its spread within a certain organization is influenced by the factors defining the structure of expected costs and rewards. A second approach – the cultural paradigm – looks at the differences in cultural traditions, social norms and interiorized values which shape individuals' moral preferences and consideration of his social and institutional role. These are a leading forces that can push a corrupt public or private agent (not) to violate legal norms. A third neo-institutional approach considers also mechanisms which allow the internal regulation of social interactions within corrupt networks, and their effects on individuals' beliefs and preferences. Though the corrupt agreements cannot be enforced with legal sanctions, several informal, non-written rules, contractual provisos and conventions may regulate the corrupt exchange between agent and corruptor. The A. underlines that corruption is the outcome of a multitude of individual and collective choices which change public opinion towards corruption and its diffusion throughout the state, markets and civil society. There is no univocal recipe to deal with anti-bribery measures, since corruption is a complex and multifaceted phenomenon. Reforms aimed at dismantling systemic corruption have to be finely tuned against its hidden governance structures, i.e. its internal regulation of exchanges and relationships. Otherwise, a vicious circle may emerge: the more an anti-corruption policy is needed, because corruption is systemic and enforced by effective third-parties, the less probable its formulation and implementation. Only when official rules are complemented by coherent informal institutions, bottom-up initiatives, they tend to produce the expected outcomes and make anticorruption regulation more effective.

Analitica dedica gran parte del suo decimo volume (2017) all'indagine della teoria e dell'analisi musicale in quanto prassi influenzata da scelte politiche e pragmatiche, e pienamente inserita in specifici contesti ideologici e sociali. Recentemente, infatti, il dibattito sulle motivazioni e gli scopi della musicologia, considerata come pratica sociale, ha portato a una nuova consapevolezza dei presupposti ideologici e politici dell'analisi musicale [Broman-Engebretsen 2007; Buch-Donin-Feneyrou 2013] e a una storicizzazione delle contrapposizioni introdotte dalla New Musicology nell'ultimo ventennio del Novecento [Agawu 2004; MacCutcheon 2014]. Allo stesso tempo, la progressiva convergenza delle metodologie impiegate nei diversi campi degli studi musicali – dalla musica d'arte alle musiche di tradizione orale, dalla popular music alla musica nel contesto della comunicazione audiovisiva, dall'uso del suono nei nuovi media alle culture non-musicali del suono – ha messo in piena evidenza la stretta relazione tra le pratiche dell'analisi musicale e i loro fondamenti epistemologici, che riflettono, in modo più o meno evidente, precise scelte di politica culturale [van den Toorn 1996; Scherzinger 2001; Schuijer 2008, Campos-Donin 2009; Guilbault 2014; Earle 2015].Analitica dedica gran parte del suo decimo volume (2017) all'indagine della teoria e dell'analisi musicale in quanto prassi influenzata da scelte politiche e pragmatiche, e pienamente inserita in specifici contesti ideologici e sociali. Recentemente, infatti, il dibattito sulle motivazioni e gli scopi della musicologia, considerata come pratica sociale, ha portato a una nuova consapevolezza dei presupposti ideologici e politici dell'analisi musicale [Broman-Engebretsen 2007; Buch-Donin-Feneyrou 2013] e a una storicizzazione delle contrapposizioni introdotte dalla New Musicology nell'ultimo ventennio del Novecento [Agawu 2004; MacCutcheon 2014]. Allo stesso tempo, la progressiva convergenza delle metodologie impiegate nei diversi campi degli studi musicali – dalla musica d'arte alle musiche di tradizione orale, dalla popular music alla musica nel contesto della comunicazione audiovisiva, dall'uso del suono nei nuovi media alle culture non-musicali del suono – ha messo in piena evidenza la stretta relazione tra le pratiche dell'analisi musicale e i loro fondamenti epistemologici, che riflettono, in modo più o meno evidente, precise scelte di politica culturale [van den Toorn 1996; Scherzinger 2001; Schuijer 2008, Campos-Donin 2009; Guilbault 2014; Earle 2015].

With the proliferation of social media, textual emotion analysis is becoming increasingly important. Sentiment Analysis and Emotion Detection can be useful to track several applications. They can be used, for instance, in Customer Relationship Management to track sentiments towards companies and their services, or in Government Intelligence, to collect people's emotions and points of views about government decisions. It is clear that tracking reputation and opinions without appropriate text mining tools is simple infeasible. Most of these tools are based on sentiment and emotion lexicons, in which lemmas are associated with the sentiment and/or emotions they evoke. However, almost all languages but English lack high-coverage inventories of this sort. This thesis presents several sentiment analysis tasks to illustrate challenges and opportunities in this research area. We review different state-of-the-art methods for sentiment analysis and emotion detection and describe how we modeled a framework to build emotive resources, that can be effectively exploited for text affective computing. One of the main outcome of the work presented in this thesis is ItEM, which is a high-coverage Italian EMotive lexicon created by exploiting distributional methods.It has been built with a three stage process including the collection of a set of highly emotive words, their distributional expansion and the validation of the system. Since corpus-based methods reflect the type of the corpus from which they are build, in order to create a reliable lexicon we collected a new Italian corpus, namely FB-NEWS15. This collection has been created by crawling the Facebook pages of the most important Italian newspapers, which typically include a small number of posts written by the journalists and a very high number of comments inspired by long discussions among readers about such news. Finally, we describe some experiments on the sentiment polarity classification of tweets. We started from a system based on supervised learning that was originally developed for the Evalita 2014 SENTIment POLarity Classification task (Basile et al., 2014) and subsequently explored the possibility to enrich this system by exploiting lexical emotive features derived from social media texts.

In the last years, FPGAs have been heavily used in many different critical applications, such as spatial and military ones, where these devices operate in harsh environments. For this reason, research studies about faults (detection, recovery, modelling etc.) in FPGA technology are of primary concern. The main objective of this thesis is the development of an integrated environment for the analysis of fault effects in FPGA routing. The integrated environment has been developed as a Python library, named PyXEL, that integrates Xilinx Software, such as Vivado and ISE tools, and exploits a strong know-how to carry out experiments on routing faults in FPGAs in an automated way. In particular, PyXEL provides an easy way to execute design manipulation, fault injection, bitstreams manipulation, collection and analysis of results. Furthermore, PyXEL has been used for the analysis of fault effects in the interconnection network of the Xilinx Artix-7 XC7A100T FPGA. Routing faults such as conflicts and opens have been injected in the FPGA using randomly chosen Programmable- Interconnect-Points (PIPs). The experiments conducted show that it is possible to use PyXEL in order to gain insights into the real behaviours of fault effects in FPGA routing.

Space debris have been generated in the last 60 years as the by-product of the exploration and exploitation of the circumterrestrial space. Due to the dramatic growth of the number of debris in space, the active intervention by the scientific community has become necessary. Indeed, an uncontrolled increase of debris in the circumterrestrial space can provoke both environmental damages and possible risks of collision for active missions. In 2007, the United Nations General Assembly has developed a set of guidelines to limit the amount of debris generated by space launches and to minimize the possibility of later fragmentations. In this context, the Revolutionary Design of Spacecraft through Holistic Integration of Future Technologies project (ReDSHIFT) was funded by the European Union. The main idea is to approach the debris mitigation issues from different perspectives, prone to suggest innovative solutions to this pressing problem, having always in mind, beyond the specific mission requirements, the minimization of the environmental impact of the spacecraft. The first step toward this direction is to understand if the dynamical perturbations in the circumterrestrial space can drive the spacecraft toward a natural re-entry. Indeed, perturbations acting on the spacecraft can induce periodical variations in the orbital eccentricity and inclination, which can potentially be exploited. Passive solutions of this kind would be preferred if they result to be affordable for the space operators and not risky for the space environment. In the present work, we will focus on the Low Earth Orbit (LEO) region, which constitutes the most densely populated orbital environment, and on the dynamical effects caused by three different perturbations: the high-degree zonal harmonics of the geopotential, the lunisolar gravitational attraction, and the solar radiation pressure (SRP). At specific values of inclination, these perturbations can foster the orbital decay inducing a quick increase of the eccentricity, if a well-defined resonance condition is satisfied. Following the work of Schettino et al. [2017, 2019], we make a deep analysis of the role of the resonances which act on the spacecraft dynamics in LEO. By means of a numerical computation of the Fourier transform, we characterize the evolution of the eccentricity of a dense set of orbits in terms of the main spectral components. In particular, we choose a suitable set of initial conditions for quasi-circular orbits spanning the LEO region for different values of semi-major axis a, from a=R⊕+800km up to a=R⊕+1600km, where R⊕ =6378.1363km is the radius of the Earth, and inclination i, from i = 0°up to i = 90°. Moreover, we selected two different values of the area-to-mass ratio of the object, in order to understand how natural perturbations, in particular SRP, can influence the orbit dynamics, depending on the A/m value. The aim of the spectral analysis described in this thesis is to clearly link each frequency signature found in the eccentricity spectrum to the dynamical effect which generates it, in order to build a frequency cartography of the LEO region. Indeed, the detailed analysis of the principal spectral components turns out to be a powerful tool to enable a better understanding of the relative importance of each gravitational and non-gravitational perturbation in the LEO region as a function of the initial semi-major axis, eccentricity and inclination of the object. In particular, the amplitude of the spectral signature produced by a perturbation on a given orbit gives an estimate of the corresponding eccentricity variation; this quantity can be compared with the numerical results in the time domain and the analytical expressions provided by theory, in order to give a comprehensive and more robust picture of the eccentricity evolution. Together with the dynamical maps in the time domain, performed in the framework of ReDSHIFT (see, e.g., Alessi et al. [2017, 2018]), our analysis can be exploited to identify the orbits where a significant growth of eccentricity, led by one or more perturbations, can assist the passive disposal of objects at their end-of-life or to optimize the design of low-cost manoeuvres, aimed at re-entering. Indeed, for some orbits, the frequency cartography is capable to disclose effects which do not show up as clearly in the temporal maps. This thesis is organized as follows: in Chapter 1 we briefly present the issue of space debris and the recommended mitigation strategies, focusing, in particular, on the aims of the ReDSHIFT project. In Chapter 2 we describe the dynamical model adopted for the numerical propagation in the time domain. We recall the analytical developments of the natural perturbations acting on objects in LEO, and, by means of the Lagrange planetary equations, we describe the main effects on the orbital elements due to each perturbation. Furthermore, after having defined what we mean by resonant condition, we analyse different kinds of resonances, due to one or more perturbations. In particular, we focus on their effect on the eccentricity evolution, in order to compare, later in Chapter 4, our results with the analytical findings. In Chapter 3 we extensively explain the simulation scenario and the mathematical tools exploited in our study. We describe the Fourier transform and the method we used to identify the main frequency signatures, which characterize the eccentricity evolution of the orbits. Finally, in Chapter 4, we outline the numerical results of our analysis. This will be done, in turn, by describing some exemplificative cases. We provide a full description of the frequency charts, obtained with our method, comparing the results in the frequency domain with the findings in the time domain. Finally, we draw some conclusions on possible practical applications of the frequency cartography.

Nowadays, more than ever, digital forensics activities are involved in any criminal, civil or military investigation and represent a fundamental tool to support cyber-security. Investigators use a variety of techniques and proprietary software forensic applications to examine the copy of digital devices, searching hidden, deleted, encrypted, or damaged files or folders. Any evidence found is carefully analysed and documented in a "finding report" in preparation for legal proceedings that involve discovery, depositions, or actual litigation. The aim is to discover and analyse patterns of fraudulent activities. In this work, a new methodology is proposed to support investigators during the analysis process, correlating evidences found through different forensic tools. The methodology was implemented through a system able to add semantic assertion to data generated by forensics tools during extraction processes. These assertions enable more effective access to relevant information and enhanced retrieval and reasoning capabilities.