Scientific Review on the Ionospheric Absorption and Research Prospects of a Complex Eikonal Model for One-Layer Ionosphere

The present paper conducts a scientific review on ionospheric absorption, extrapolating the research prospects of a complex eikonal model for one-layer ionosphere. As regards the scientific review, here a quasi-longitudinal (QL) approximation for nondeviative absorption is deduced which is more refined than the corresponding equation reported by Davies (1990). As regards the research prospects, a complex eikonal model for one-layer ionosphere is analyzed in depth here, already discussed by Settimi et al. (2013). A simple formula is deduced for a simplified problem. A flat, layered ionospheric medium is considered, without any horizontal gradient. The authors prove that the QL nondeviative amplitude absorption according to the complex eikonal model is more accurate than Rawer's theory (1976) in the range of middle critical frequencies

Caratterizzazione di Sensori UWB per Radiolocalizzazione

Lo scopo di questa tesi è quello di avvalorare con misure sperimentali, l’idea di OTO Melara di realizzare un innovativo Unmanned air vehicle Automatic Guidance (U.A.G.), cioè un sistema di pilotaggio semi-automatico su brevi distanze di velivoli UAV (Unmanned Aerial Vehicle) ad ala rotante, di piccole dimensioni e peso ridotto, utilizzabili ad esempio per la scoperta di minacce di tipo IED (Improvised Explosively Devices), VBIED (Vehicle-Borne Improvised Explosive Devices, ovvero Auto-bombe), campi minati, ecc. Tale complesso tecnologico deve supportare il sistema di guida e controllo della navigazione della piattaforma robotica, al fine di renderne più facile e precisa la gestione ed aumentarne l’accuratezza in scenari operativi definiti “caldi” in ambito militare ed umanitario. Il sistema proposto, si basa sull’ipotesi di posizionare quattro moduli UWB su un mezzo terrestre, Lince o rover, ed effettuare una radiolocalizzazione a controllo semi-automatico della posizione di un altro sensore UWB, montato sull’UAV. Le misure sperimentali portate avanti per questa tesi, si basano sui dispositivi PulsOn400 Ranging & Communication Module della TimeDomain, sensori capaci di misurare efficientemente la distanza tra un requester posto sull’UAV, e più moduli responder, fornendo l’informazione di distanza necessaria per la localizzazione ad esempio con metodo di multilaterazione. I diversi moduli UWB sono stati studiati svolgendo delle analisi preliminari, che hanno permesso di comprendere il funzionamento dei dispositivi ed ottimizzarne le prestazioni nelle successive fasi di misura; quest’ultime realizzate in ambienti outdoor, indoor ed in camera anecoica. I risultati delle analisi preliminari, dimostrano che l’errore di stima non varia sensibilmente quando il numero di misure ripetute (detto Count), su cui è basata la stima stessa, è maggiore di 80. Inoltre il valor medio del tempo necessario ad effettuare la singola misura (StopWatch Time), risulta essere strettamente legato all’indice d’integrazione degli impulsi (PII), ed indipendente dalla distanza, potenza trasmessa e Count. Infine, considerando un set di più di 40.000 misure, è stato possibile concludere che in media, per i tre scenari considerati ed in condizione di LOS (Line Of Sight), la precisione di stima in distanza, in termini di deviazione standard, è sempre dell’ordine di qualche centimetro; mentre aumenta di un ordine di grandezza quando viene interposto tra i moduli un ostacolo con attenuazione considerevole, come quella di un muro portante di un edificio. I parametri estratti durante le campagne di misura discusse nella tesi, verranno utilizzati per implementare un modello del sistema di pilotaggio semi-automatico basato su sensori UWB, come i P400 RCM della TimeDomain

Oblique ionograms automatic scaling and eikonal based ray tracing

A method for automatic scaling of oblique ionograms has been introduced. This method also provides a rejection procedure for ionograms that are considered to lack sufficient information, depicting a very good success rate. Observing the Kp index of each autoscaled ionogram, can be noticed that the behavior of the autoscaling program does not depend on geomagnetic conditions. The comparison between the values of the MUF provided by the presented software and those obtained by an experienced operator indicate that the procedure developed for detecting the nose of oblique ionogram traces is sufficiently efficient and becomes much more efficient as the quality of the ionograms improves. These results demonstrate the program allows the real-time evaluation of MUF values associated with a particular radio link through an oblique radio sounding. The automatic recognition of a part of the trace allows determine for certain frequencies, the time taken by the radio wave to travel the path between the transmitter and receiver. The reconstruction of the ionogram traces, suggests the possibility of estimating the electron density between the transmitter and the receiver, from an oblique ionogram. The showed results have been obtained with a ray-tracing procedure based on the integration of the eikonal equation and using an analytical ionospheric model with free parameters. This indicates the possibility of applying an adaptive model and a ray-tracing algorithm to estimate the electron density in the ionosphere between the transmitter and the receiver An additional study has been conducted on a high quality ionospheric soundings data set and another algorithm has been designed for the conversion of an oblique ionogram into a vertical one, using Martyn's theorem. This allows a further analysis of oblique soundings, throw the use of the INGV Autoscala program for the automatic scaling of vertical ionograms

Enhancing the dimensional accuracy of a low-cost 3D printer

3D printing is widely used in the entertainment industry by filmmakers, effect studios and game designers to easily and fast fabricate characters or objects that are first virtually modelled through Computer Graphics. There are several commercial proposals in the field of low-cost 3D printers, with prices starting from a few hundred euros for kits that the users should assemble by themselves. However, their performances in terms of part accuracy are quite limited and are basically the consequence of a lack of optimization both in mechanical terms as in software. Starting from these considerations, an optimization project was assigned to the students of the Specializing Master in Industrial Automation of the Politecnico di Torino. The Master is developed in collaboration with COMAU S.p.a., a company worldwide leader in automation expecially for the automotive sector. The task of enhancing the performances of the 3D printer Prusa i3, that is supplied in the assembly box, was assigned to sixteen engineers attending the Master who were divided into 4 groups. The activities have led to the birth of four new 3D printers: Fluo, Ghost, Metallica and Print-Doh. In order to assess and validate the improvements, a benchmarking activity was carried out to evaluate the dimensional accuracy of the four printers. The benchmarking was based on the manufacturing of an innovative reference artifact whose geometrical features are designed to fit within different ISO basic sizes. Each group printed a replica of the reference part with their own new printer and then the replicas were measured by means of a coordinate measuring machine (CMM). Measures were used to compare the performances of the four printers and the results of the benchmarking considers the dimensional accuracy of the replicas in terms of ISO IT grades, but also the form errors of the geometrical features through GD&T tolerances

Burnout in cardiac anesthesiologists. results from a national survey in italy

Objective: There is increasing burnout incidence among medical disciplines, and physicians working in emergency settings seem at higher risk. Cardiac anesthesiology is a stressful anesthesiology subspecialty dealing with high-risk patients. The authors hypothesized a high risk of burnout in cardiac anesthesiologists. Design: National survey conducted on burnout Setting: Italian cardiac centers. Participants: Cardiac anesthesiologists. Interventions: The authors administered via email an anonymous questionnaire divided into 3 parts. The first 2 parts evaluated workload and private life. The third part consisted of the Maslach Burnout Inventory test with its 3 constituents: high emotional exhaustion, high depersonalization, and low personal accomplishment. Measurements and Main Results: The authors measured the prevalence and risk of burnout through the Maslach Burnout Inventory questionnaire and analyzed factors influencing burnout. Among 670 contacts from 71 centers, 382 cardiac anesthesiologists completed the survey (57%). The authors found the following mean Maslach Burnout Inventory values: 14.5 ± 9.7 (emotional exhaustion), 9.1 ± 7.1 (depersonalization), and 33.7 ± 8.9 (personal accomplishment). A rate of 34%, 54%, and 66% of respondents scored in “high” or “moderate-high” risk of burnout (emotional exhaustion, depersonalization, and personal accomplishment, respectively). The authors found that, if offered to change subspecialty, 76% of respondents would prefer to remain in cardiac anesthesiology. This preference and parenthood were the only 2 investigated factors with a protective effect against all components of burnout. Significantly lower burnout scores were found in more experienced anesthesiologists. Conclusion: A relatively high incidence of burnout was found in cardiac anesthesiologists, especially regarding high depersonalization and low personal accomplishment. Nonetheless, most of the respondents would choose to remain in cardiac anesthesiology

Surgical treatment of central grade 1 chondrosarcoma of the appendicular skeleton.

Diagnosis and treatment of low-grade chondrosarcoma remain controversial. We performed a review of a single-center series with the aims of assessing the oncologic outcome of these patients, verifying if intralesional curettage can be adequate treatment, and defining clinical criteria to support the surgeon and the oncologist in decision-making for surgery and subsequent follow-up