Antipodal random sequences with prescribed second-order statistics: application to Compressive Sensing and UWB system based on DS-CDMA

It is usual to hear a strange short sentence: «Random is better than...». Why is randomness a good solution to a certain engineering problem? There are many possible answers, and all of them are related to the considered topic. In this thesis I will discuss about two crucial topics that take advantage by randomizing some waveforms involved in signals manipulations. In particular, advantages are guaranteed by shaping the second order statistic of antipodal sequences involved in an intermediate signal processing stages. The first topic is in the area of analog-to-digital conversion, and it is named Compressive Sensing (CS). CS is a novel paradigm in signal processing that tries to merge signal acquisition and compression at the same time. Consequently it allows to direct acquire a signal in a compressed form. In this thesis, after an ample description of the CS methodology and its related architectures, I will present a new approach that tries to achieve high compression by design the second order statistics of a set of additional waveforms involved in the signal acquisition/compression stage. The second topic addressed in this thesis is in the area of communication system, in particular I focused the attention on ultra-wideband (UWB) systems. An option to produce and decode UWB signals is direct-sequence spreading with multiple access based on code division (DS-CDMA). Focusing on this methodology, I will address the coexistence of a DS-CDMA system with a narrowband interferer. To do so, I minimize the joint effect of both multiple access (MAI) and narrowband (NBI) interference on a simple matched filter receiver. I will show that, when spreading sequence statistical properties are suitably designed, performance improvements are possible with respect to a system exploiting chaos-based sequences minimizing MAI only.

Drugstore Bologna. Una lettura del rapporto tra la città e la droga

The main task of this research is to investigate the situation of drugs in the city of Bologna. A first discussion pertains the method to adopt studying an ethical question as drug actually is. In fact it is widely known that drugs problem involves many political and religious considerations which are misleading in a scientific point of view. After a methodological chapter supposed to show the purpose of this research, it is discussed a logical definition of drugs. There it is examined an aristotelian definition of drugs with semantic instruments from philosophy of the language to fulfil meaning of terms. The following chapter discusses personal stories of different people involved in drug in the city, who actually represent the main characters of drug subculture. Afterwards the official statistics concerning drug enforcement is discussed and compared with a specific police action which allows to criticize that data, and to make some hypothesis about drug quantities circulating in town. Next step is investigating drugs addicted in town, with a validation technique of data base queries. The result is a statistics of users in which there is evidence of main presence of foreigners and not resident Italians who use to practice drugs in this city. Demographic analysis of identified people shows that drug addiction is widely diffused among all range of age and mainly pertains males, with an increasing trend. Then is examined the geographic distribution of users residence and use places, showing that drugs abuse is spread among all classes of population, while drugs squares are located in some points of town which realise a kind of drug area with a concentration of dealers not organised together. With some detailed queries in police reports statistics is studied some specific subject on nowadays drug abuse, the phenomenon of multi-use, the relation between drug and crime, the relation between drug and mental disease, recording some evidence in such topics. Finally a survey on city media along last two years shows the interest about this topic and gives an idea of public opinion’s information about drugs. The study refers to the city of Bologna only, and pertains data recorded along last ten years by the local metropolitan police corp.

"Making Sense of Figures": Statistics, Computing and Information Technologies in Agriculture and Biology in Britain, 1920s-1960s

Throughout the twentieth century statistical methods have increasingly become part of experimental research. In particular, statistics has made quantification processes meaningful in the soft sciences, which had traditionally relied on activities such as collecting and describing diversity rather than timing variation. The thesis explores this change in relation to agriculture and biology, focusing on analysis of variance and experimental design, the statistical methods developed by the mathematician and geneticist Ronald Aylmer Fisher during the 1920s. The role that Fisher’s methods acquired as tools of scientific research, side by side with the laboratory equipment and the field practices adopted by research workers, is here investigated bottom-up, beginning with the computing instruments and the information technologies that were the tools of the trade for statisticians. Four case studies show under several perspectives the interaction of statistics, computing and information technologies, giving on the one hand an overview of the main tools – mechanical calculators, statistical tables, punched and index cards, standardised forms, digital computers – adopted in the period, and on the other pointing out how these tools complemented each other and were instrumental for the development and dissemination of analysis of variance and experimental design. The period considered is the half-century from the early 1920s to the late 1960s, the institutions investigated are Rothamsted Experimental Station and the Galton Laboratory, and the statisticians examined are Ronald Fisher and Frank Yates.