Dissecting Ponzi schemes on Ethereum: identification, analysis, and impact

Ponzi schemes are financial frauds which lure users under the promise of high profits. Actually, users are repaid only with the investments of new users joining the scheme: consequently, a Ponzi scheme implodes soon after users stop joining it. Originated in the offline world 150 years ago, Ponzi schemes have since then migrated to the digital world, approaching first the Web, and more recently hanging over cryptocurrencies like Bitcoin. Smart contract platforms like Ethereum have provided a new opportunity for scammers, who have now the possibility of creating "trustworthy" frauds that still make users lose money, but at least are guaranteed to execute "correctly". We present a comprehensive survey of Ponzi schemes on Ethereum, analysing their behaviour and their impact from various viewpoints

Experimental determination of the particle dynamics into a rotating tube

This paper reports the procedure for analysing the biomass powder bed characteristics realized in an experimental pyrolysis reactor. The reaction apparatus is made of a quartz tube which can rotate, horizontally or slightly inclined, with different speeds. Depending on the tube inclination and rotation, different motion conditions (regime, hold-up, residence time and advancing rate) are possible; also the particle characteristics (nature, shape and size, humidity) and the flow rate affect the bed behaviour. After taking some pictures of the bed from the discharge side, they can be analysed by means of the geometry rules; this procedure is here described. In this way the bed profile can be obtained, and this information can be used to calculate the parameters of a proper model, already developed. The methodology here presented will be used in the future to find data to be used in the development of a whole pyrolysis process model including also heat exchange, gas fluid dynamics and pyrolysis reaction kinetics

Kinetic modelling of the gas-phase water oxidation of light hydrocarbons

The conversion of solid and liquid fuels to gas, whenever possible, is an important way for improving the efficiency and cleanness of processes. This paper presents the kinetic modelling of the water oxidation of light hydrocarbons in the gas phase at 500 °C with mixtures of heptane and water in different amounts. The aim of the work was to find information about kinetics of the homogeneous chemical reactions which take place in the gas phase during the biomass processing, particularly pyrolysis, performed with water steam as the oxidizing reactant. The experimental data here used were obtained by a continuous stainless steel reactor placed inside a heated muffle oven and maintained at a constant temperature. The gaseous product, after separation of the condensable components, was analysed by an in-line gas chromatograph. The apparatus showed to be effective for future operations with different experimental conditions (temperature and feed). The obtained data will be integrated with those coming from parallel studies about the biomass wet pyrolysis for gas production

Popularity Does Not Always Mean Triviality: Introduction of Popularity Criteria to Improve the Accuracy of a Recommender System

n/

Enhancing workplace safety: A flexible approach for personal protective equipment monitoring

Workplace safety is a prominent concern, motivating researchers across diverse disciplines to investigate valuable ways to address its challenges. However, creating an efficient system to address this issue remains a significant challenge. Since many accidents happen due to improper usage or complete removal of Personal Protective Equipment (PPE), one straightforward method for enhancing workplace security involves monitoring their usage This paper introduces an Operator Area Network (OAN) system which improves the existing solutions by increasing portability across different users and environments, non-intrusiveness and privacy. To enhance robustness in detecting the situations in which PPEs are not used correctly, we take advantage of Machine Learning to analyse the received signal strength indicator (RSSI) between PPEs in the same OAN The novelty of this work is that it does not exploit RSSI as a proxy of the distance but instead recognizes a signature of the correct wearing of the PPE By employing this system, employers can effectively ensure the proper usage of PPE devices at their worksites while also minimizing any adverse effects on workers’ comfort and reducing the setup burden for employers. The system runs a Support Vector Machine (SVM) model several times per second and employs a post-processing algorithm to enhance its initial accuracy further As a result, the system effectively reduces false positives by about 80% and swiftly detects instances of improper usage of the worker’s PPE, raising the alarm in less than seven seconds. Moreover, the post-processing algorithm can be customized to meet the specific needs of different use cases, allowing for a flexible trade-off between the detection time interval and the overall accuracy of the detection system

Studio di alcune caratteristiche compositive di oli extra vergini di oliva sardi in relazione all'origine geografica

Percent trygliceride composition, total carotenoids and chlorophylles and the main quality parameters of 110 extra-virgin oils of the five most important Sardinian production places have been inspected. Statistical analysis of data revealed that some of the above cited components can serve as discriminant factors to exactly define the origin of the oil, while others do not. In particular, it has been found that an exact identification of the place of origin is easily achieved for zones 2 (south Sardinia) and 3 (north-west Sardinia), because they show the significantly highest content of POL triglyceride and palmitoleic acid or SOO triglyceride and stearic acid, respectively. Moreover, zones 2 and 3 have the significant lowest content of OOO and PSO triglycerides, respectively. A cross comparison of parameters allows the place of origin identification for the remaining zones as well. Su 110 oli vergini d'oliva provenienti dalle cinque principali zone olivicole della Sardegna sono stati determinati: composizione percentuale in trigliceridi ed in acidi grassi, contenuto di caroteni e clorofille totali e alcuni parametri primari della qualita. L'elaborazione statistica dei risultati ottenuti ha permesso di individuare la presenza di alcuni componenti, che fungono da discriminanti in funzione della zona di provenienza degli oli. Altri componenti, invece, risultano omogenei tra l'intera produzione sarda. In particolare, si è visto che è possibile discriminare agevolmente gli oli della zona 2 (Sardegna meridionale) e 3 (Sardegna nordoccidentale) perchè presentano il più alto contenuto dal punto di vista statistico (P<0,001) del trigliceride POL e di acido palmitoleico o della SOO e dell'acido stearico, rispettivamente. Contemporaneamente, inoltre, hanno il più basso contenuto dei trigliceridi 000 (zona 2) e PSO (zona 3). Per le altre zone, invece, è possibile, tramite il controllo di più parametri, risalire alia provenienza

Multi-scale deep learning ensemble for segmentation of endometriotic lesions

Ultrasound is a readily available, non-invasive and low-cost screening for the identification of endometriosis lesions, but its diagnostic specificity strongly depends on the experience of the operator. For this reason, computer-aided diagnosis tools based on Artificial Intelligence techniques can provide significant help to the clinical staff, both in terms of workload reduction and in increasing the overall accuracy of this type of examination and its outcome. However, although these techniques are spreading rapidly in a variety of domains, their application to endometriosis is still very limited. To fill this gap, we propose and evaluate a novel multi-scale ensemble approach for the automatic segmentation of endometriosis lesions from transvaginal ultrasounds. The peculiarity of the method lies in its high discrimination capability, obtained by combining, in a fusion fashion, multiple Convolutional Neural Networks trained on data at different granularity. The experimental validation carried out shows that: (i) the proposed method allows to significantly improve the performance of the individual neural networks, even in the presence of a limited training set; (ii) with a Dice coefficient of 82%, it represents a valid solution to increase the diagnostic efficacy of the ultrasound examination against such a pathology

A Tool to Analyze the Reading Behavior of the Users in a Mobile Digital Publishing Platform

Abstract. In their daily activities, users interact multiple times with mobile applications. This generates huge amounts of data related to these interactions that, when filtered and analyzed, would give insights on the behavior of the users while using an application. In this paper, we consider a real-world mobile digital publishing platform, named Viewerplus, which enables a digital, augmented fruition of content from traditional magazines. The objective is to develop a tool that allows the human editors to analyze the reading behavior of the users, by providing analytics that show how the users read magazine issues (i.e., how they browse an issue and move inside the app, which portions of an issue are most frequently read and which frequency, and which topics are of interest for the users during a reading session). The tool has been developed by employing a dataset extracted from the reading sessions of a magazine of an important international publisher. In this work we also employ the dataset to present a preliminary study of the user reading behavior

Flexible In-Ga-Zn-O based circuits with two and three metal layers: simulation and fabrication study

The quest for high-performance flexible circuits call for scaling of the minimum feature size in Thin-Film Transistors (TFTs). Although reduced channel lengths can guarantee an improvement in the electrical properties of the devices, proper design rules also play a crucial role to minimize parasitics when designing fast circuits. In this letter, systematic Computer-Aided Design (CAD) simulations have guided the fabrication of highperformance flexible operational amplifiers (opamps) and logic circuits based on Indium-Gallium-Zinc-Oxide (IGZO) TFTs. In particular, the performance improvements due to the use of an additional third metal layer for the interconnections has been estimated for the first time. Encouraged by the simulated enhancements resulting by the decreased parasitic resistances and capacitances, both TFTs and circuits have been realized on a free-standing 50μm thick polymide foil using three metal layers. Despite the thicker layer stack, the TFTs have shown mechanical stability down to 5mm bending radii. Moreover, the opamps and the logic circuits have yielded improved electrical performance with respect to the architecture with two metal layers: gainbandwidth- product (GBWP) increased by 16:9%, for the first one, and propagation delay (tpd) decreased by 43%, for the latter one