Real-time and distributed applications for dictionary-based data compression

The greedy approach to dictionary-based static text compression can be executed by a finite state machine. When it is applied in parallel to different blocks of data independently, there is no lack of robustness even on standard large scale distributed systems with input files of arbitrary size. Beyond standard large scale, a negative effect on the compression effectiveness is caused by the very small size of the data blocks. A robust approach for extreme distributed systems is presented in this paper, where this problem is fixed by overlapping adjacent blocks and preprocessing the neighborhoods of the boundaries. Moreover, we introduce the notion of pseudo-prefix dictionary, which allows optimal compression by means of a real-time semi-greedy procedure and a slight improvement on the compression ratio obtained by the distributed implementations

What effect does network size have on NRTK positioning?

The Network Real Time Kinematic (NRTK) positioning is nowadays a very common practice not only in academia but also in the professional world. To support the users several networks of Continuous Operating Reference Stations (CORSs) were born. These networks offer real-time services for NRTK positioning, providing a centimetric positioning accuracy with an average distance of 25-35 kms between the reference stations. But what is the effective distance between reference stations that allows to achieve the precision required for real-time positioning, using both geodetic and GIS receivers? How the positional accuracy changes with increasing distances between CORS? Can a service of geostationary satellites, such as the European EGNOS, be an alternative to the network positioning for medium-low cost receivers? These are only some of the questions that the Authors try to answer in this articl

Stability, Flying Qualities and Parameter Estimation of a Twin-Engine CS23/FAR23 Certified Light Aircraft

This paper presents some results of the flight test campaign conducted on the Tecnam P2006T aircraft, on the occasion of its certification process. This twin-engine propeller airplane is certified in the category CS23/FAR23. Many preliminary flight tests on a prototype of this light aircraft were aimed at optimizing performances and flight qualities. These experiences led to the application of two winglets to the original wing. The final configuration was extensively tested for the purpose of CS23 certification achievement. At the same time the airplane model, through a dedicated set of flight maneuvers, has been characterized by means of parameter estimation studies. The longitudinal and lateral-directional response mode were assessed and quantified. All the aircraft stability derivatives have been estimated from the acquired flight data using the well-known Maximum Likelihood Method (MLM). Some estimated stability derivatives have been also compared with the corresponding values extracted from leveled flight tests and from wind-tunnel tests performed on a scaled model of the aircraft

Circadian Rhythm Abnormalities in Parkinson's Disease from Humans to Flies and Back

Clinical and research studies have suggested a link between Parkinson\u2019s disease (PD) and alterations in the circadian clock. Drosophila melanogaster may represent a useful model to study the relationship between the circadian clock and PD. Apart from the conservation of many genes, cellular mechanisms, signaling pathways, and neuronal processes, Drosophila shows an organized central nervous system and well-characterized complex behavioral phenotypes. In fact, Drosophila has been successfully used in the dissection of the circadian system and as a model for neurodegenerative disorders, including PD. Here, we describe the fly circadian and dopaminergic systems and report recent studies which indicate the presence of circadian abnormalities in some fly PD genetic models. We discuss the use of Drosophila to investigate whether, in adults, the disruption of the circadian system might be causative of brain neurodegeneration. We also consider approaches using Drosophila, which might provide new information on the link between PD and the circadian clock. As a corollary, since PD develops its symptomatology over a large part of the organism\u2019s lifespan and given the relatively short lifespan of fruit flies, we suggest that genetic models of PD could be used to perform lifelong screens for drug-modulators of general and/or circadian-related PD traits

Search for new physics contributions entering the tWb electroweak vertex at 13 TeV with the CMS experiment

The Standard Model (SM) of Particles Physics is the current framework in which the electromagnetic, weak, and strong interactions successfully find an explanation. The SM is verified with high precision for most processes it describes, and all particles it predicted have been now been observed, after the discoveries of the Higgs boson at the LHC in 2012 and of the top quark at the TeVatron in 1994. Since then, intense studies have been performed to measure the features and the properties of such particles and their couplings. The top quark in particular holds a special place in the Standard Model, as it is the most massive elementary particle ever discovered. As a consequence of its mass, it is also characterised by a very short lifetime: the decay occurs before it can hadronise, implying that most of the top quark properties can be directly inferred from the its decay products, as if it was a free particle. Another notable feature of top quark physics is that a distinct hierarchy can be identified in top quark decays: it almost exclusively decays in a W boson and a b quark. Decay modes in a W boson and a d or s quarks are allowed, but they are strongly suppressed, so much that up to now they have never been studied directly. This feature stems from the fact that there is a distinct preference of top quarks for couplings with b quarks via electroweak charged current interactions. The mixing among families is regulated in the SM by a matrix of fundamental parameters named the Cabibbo-Kobayashi-Maskawa (CKM) matrix. Through the study of top quark decays and electroweak couplings it is possible to extract the magnitude of the CKM matrix elements related to the third row, which, according to constraints from low energy measurements, should exhibit a remarkable hierarchical structure. Such hierarchical structure might also be an indication of a new more fundamental underlying physics model. In order to precisely study this sector of the SM, the best tool currently available is the Large Hadron Collider (LHC). The LHC is a circular accelerator designed to provide proton-proton collisions with a luminosity of 10$^{34}$ cm$^{−2}$s$^{−1}$ and a centre-of-mass energy of sqrt(s) = 14 TeV. The LHC is equipped with four main experiments: ALICE, ATLAS, CMS, and LHCb. The aim of LHC is to provide further proof on the validity of the SM and to give clues of new physics at the TeV scale. The first goal of the present thesis work is the first direct measurement of the CKM matrix elements |Vtb|,|Vts| and |Vtd| in events where single top quarks are produced via electroweak charged-current interactions. The main mechanisms for electroweak charged current production of single top quarks is the t−channel. The data analysed correspond to an integrated luminosity of 35.9 fb$^{−1}$ of proton-proton collisions at a centre-of-mass energy of sqrt(s) = 13 TeV collected with the CMS experiment at the LHC during 2016. The performed analysis explicitly probes in great detail the left-handed only interactions at the tWb vertex at energy regimes around the electroweak scale. New physics might rise in right-handed couplings, or manifest at higher energy regimes, both indirectly or directly via new resonances. There is experimental evidence, both in particle physics and in astrophysics observations, suggesting that the SM in not the ultimate fundamental theory. Many physics models have been proposed to extend it in a more general picture, so to provide an explanation to such phenomena, and several of them predict new particles that could have a mass larger than the one of the top quark. The top quark could therefore have a privileged relationship with new physics particles and play a crucial role in their discovery. The LHC is the perfect tool to perform direct searches for new particles thanks to the high-energy collisions and the large number of top quark produced. In the present work a search for a beyond the SM W′ boson decaying in tb quarks in leptonic final states is presented. Data from proton-proton collisions with a centre-of-mass energy of sqrt(s) = 13 TeV, corresponding to 137.2 fb$^{−1}$, collected by the CMS experiment at the LHC from 2016 to 2018 are analysed. An upgrade of the LHC accelerator complex in the next years will allow to significantly increase the collision rate, further improving the results obtained so far and effectively extending the physics reach of the machine. The CMS experiment foresees a series of detector upgrades to cope with the new challenging conditions. Part of this work documents the testing and validation of the Gas Electron Multiplier chambers that are part of the Muon System upgrade

P-complete problems in data compression

AbstractIn this paper we study the parallel computational complexity of some methods for compressing data via textual substitution. We show that the Ziv-Lempel algorithm and two standard variations are P-complete. Hence an efficient parallelization of these algorithms is not possible unless P = NC

Lempel-Ziv Data Compression on Parallel and Distributed Systems

We present a survey of results concerning Lempel-Ziv data compression on parallel and distributed systems, starting from the theoretical approach to parallel time complexity to conclude with the practical goal of designing distributed algorithms with low communication cost. An extension by Storer to image compression is also discussed

Flow curvature effects on dynamic behaviour of a novel vertical axis tidal current turbine: numerical and experimental analysis

The paper deals with performances analysis of vertical axis turbine to exploit tidal marine currents. Flow curvature effects on performences of a novel vertical axis turbine have been investuigated. It has been shown that the flow curvature effect allows to design properly an accurate airfoil shape to increase turbine performances

Earthquake forecasting: a possible solution considering the GPS ionospheric delay

Abstract. The recent earthquakes in L'Aquila (Italy) and in Japan have dramatically emphasized the problem of natural disasters and their correct forecasting. One of the aims of the research community is to find a possible and reliable forecasting method, considering all the available technologies and tools. Starting from the recently developed research concerning this topic and considering that the number of GPS reference stations around the world is continuously increasing, this study is an attempt to investigate whether it is possible to use GPS data in order to enhance earthquake forecasting. In some cases, ionospheric activity level increases just before to an earthquake event and shows a different behaviour 5–10 days before the event, when the seismic event has a magnitude greater than 4–4.5 degrees. Considering the GPS data from the reference stations located around the L'Aquila area (Italy), an analysis of the daily variations of the ionospheric signal delay has been carried out in order to evaluate a possible correlation between seismic events and unexpected variations of ionospheric activities. Many different scenarios have been tested, in particular considering the elevation angles, the visibility lengths and the time of day (morning, afternoon or night) of the satellites. In this paper, the contribution of the ionospheric impact has been shown: a realistic correlation between ionospheric delay and earthquake can be seen about one week before the seismic event