P-RANSAC: An Integrity Monitoring Approach for GNSS Signal Degraded Scenario

Satellite navigation is critical in signal-degraded environments where signals are corrupted and GNSS systems do not guarantee an accurate and continuous positioning. In particular measurements in urban scenario are strongly affected by gross errors, degrading navigation solution; hence a quality check on the measurements, defined as RAIM, is important. Classical RAIM techniques work properly in case of single outlier but have to be modified to take into account the simultaneous presence of multiple outliers. This work is focused on the implementation of random sample consensus (RANSAC) algorithm, developed for computer vision tasks, in the GNSS context. This method is capable of detecting multiple satellite failures; it calculates position solutions based on subsets of four satellites and compares them with the pseudoranges of all the satellites not contributing to the solution. In this work, a modification to the original RANSAC method is proposed and an analysis of its performance is conducted, processing data collected in a static test

A Galileo IOV Assessment: Measurement and Position Domain

The European GNSS, Galileo, is currently in its In-Orbit Validation (IOV) phase where four satellites are finally available for computing the user position. In this phase, the analysis of the measurements and Position Velocity and Time (PVT) obtained from the IOV satellites can provide insight on the potentialities of the Galileo system. A methodology is suggested for the analysis of the Galileo IOV pseudorange and pseudorange rates collected from the E1 and E5 frequencies. Several days of data were collected and processed to determine figures of merits such as RMS and maximum errors of the Galileo observables. From the analysis, it emerges that Galileo is able to achieve better accuracy with respect to GPS. A thorough analysis of the PVT performance is also achieved using broadcast ephemerides. Galileo and GPS PVTs are compared under similar geometry conditions showing the potential of the Galileo system.JRC.G.5-Security technology assessmen

Automatic recognition of military vehicles with Krawtchouk moments

The challenge of Automatic Target Recognition (ATR) of military targets within a Synthetic Aperture Radar (SAR) scene is addressed in this paper. The proposed approach exploits the discrete defined Krawtchouk moments, that are able to represent a detected extended target with few features, allowing its characterization. The proposed algorithm provides robust performance for target recognition, identification and characterization, with high reliability in presence of noise and reduced sensitivity to discretization errors. The effectiveness of the proposed approach is demonstrated using the MSTAR dataset

High Pressure Assisted Coronary Stent Implantation Accomplished Without Intravascular Ultrasound Guidance and Subsequent Anticoagulation

AbstractObjectives. The purpose of this study was to determine the efficacy of treatment with antiplatelet therapy and no anticoagulation after high pressure assisted coronary stent implantation performed without intravascular ultrasound (IVUS) guidance.Background. Previous studies have shown that during IVUS-guided Palmaz-Schatz coronary stenting, it is safe to withhold anticoagulation when stent expansion has been optimized by high pressure balloon dilation.Methods. Patients that had successful coronary stenting without IVUS guidance were treated with ticlopidine, 500 mg/day, and aspirin, 325 mg/day, for 1 month and then received only aspirin, 325 mg/day, indefinitely. Patients were not treated with warfarin (Coumadin) or heparin after successful stenting. Clinical and angiographic events were assessed at 1 month.Results. A total of 201 intracoronary stents were implanted in 127 patients with 137 lesions. The average number of stents per lesion was 1.4 ± 0.8, and the average number of stents per patient was 1.6 ± 1.1. Stent deployment was performed for elective indications in 79% of procedures and for emergency indications in 21%. There were four stent thrombosis events for a per patient event rate of 3.1% and a per lesion event rate of 2.9%.Conclusions. After high pressure assisted stenting performed without IVUS guidance, there was an acceptable incidence of 3.1% of stent thrombosis with the combination of short-term ticlopidine and aspirin therapy and no anticoagulation. Although the study involved only 127 patients, the results support the relative safety of stenting without IVUS guidance and with antiplatelet therapy only in comparison to historical trials on stenting performed with postprocedure anticoagulation.(J Am Coll Cardiol 1977;29:21–7)

3D Localization and Tracking Methods for Multi-Platform Radar Networks

Multi-platform radar networks (MPRNs) are an emerging sensing technology due to their ability to provide improved surveillance capabilities over plain monostatic and bistatic systems. The design of advanced detection, localization, and tracking algorithms for efficient fusion of information obtained through multiple receivers has attracted much attention. However, considerable challenges remain. This article provides an overview on recent unconstrained and constrained localization techniques as well as multitarget tracking (MTT) algorithms tailored to MPRNs. In particular, two data-processing methods are illustrated and explored in detail, one aimed at accomplishing localization tasks the other tracking functions. As to the former, assuming a MPRN with one transmitter and multiple receivers, the angular and range constrained estimator (ARCE) algorithm capitalizes on the knowledge of the transmitter antenna beamwidth. As to the latter, the scalable sum-product algorithm (SPA) based MTT technique is presented. Additionally, a solution to combine ARCE and SPA-based MTT is investigated in order to boost the accuracy of the overall surveillance system. Simulated experiments show the benefit of the combined algorithm in comparison with the conventional baseline SPA-based MTT and the stand-alone ARCE localization, in a 3D sensing scenario

Identification of Walker Identity Using Smartphone Sensors: An Experiment Using Ensemble Learning

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Insights into the interaction of the N-terminal amyloidogenic polypeptide of ApoA-I with model cellular membranes

BACKGROUND: About twenty variants of apolipoprotein A-I (ApoA-I) are associated to hereditary systemic amyloidoses. Although the molecular bases of this disease are still largely unknown, it has been hypothesized that ApoA-I proteolysis is a key event in pathogenesis, since it triggers the release of an N-terminal fragment (80-100 residue long) that misfolds to form amyloid deposits in peripheral organs and tissues. It is also known that cell membrane lipids play a key role in the fibrillogenic pathway. In the case of ApoA-I related amyloidosis caused by L174S mutation, the 93-residue N-terminal fragment of ApoA-I ([1-93]ApoA-I) was found to be the major constituent of ex vivo fibrils. METHODS: With the main goal to investigate the interaction of either [1-93]ApoA-I and ApoA-I with biomimetic membranes, we set-up an experimental system based on the Raman Tweezers methodology. We tested GUVs composed by two types of zwitterionic lipids with a different fluidity degree, i.e. dioleoylphosphatidylcholine (DOPC) and dipalmitoylphosphatidylcholine (DPPC). RESULTS: We found that [1-93]ApoA-I induces conformational disorder in an ordered lipid bilayer. When interacting with fluid phases, instead, the fragment was found to be able to penetrate the membrane bilayer inducing an alignment of lipid chains. CONCLUSIONS: The interaction features of [1-93]ApoA-I with biomimetic membranes strongly depend on the lipid phase. Full-length ApoA-I was found to have similar effects, even if significantly less pronounced. GENERAL SIGNIFICANCE: Our observations shed light on still largely unknown molecular bases of ApoA-I fibrillogenic domain interaction with membranes

On model, algorithms and experiment for micro-doppler based recognition of ballistic targets

The ability to discriminate between Ballistic Missile warheads and confusing objects is an important topic from different points of view. In particular, the high cost of the interceptors with respect to tactical missiles may lead to an ammunition problem. Moreover, since the time interval in which the defence system can intercept the missile is very short with respect to target velocities, it is fundamental to minimise the number of shoots per kill. For this reason a reliable technique to classify warheads and confusing objects is required. In the efficient warhead classification system presented in this paper a model and a robust framework is developed, which incorporates different microDoppler based classification techniques. The reliability of the proposed framework is tested on both simulated and real dat

Space-based Global Maritime Surveillance. Part I: Satellite Technologies

Maritime surveillance (MS) is crucial for search and rescue operations, fishery monitoring, pollution control, law enforcement, migration monitoring, and national security policies. Since the early days of seafaring, MS has been a critical task for providing security in human coexistence. Several generations of sensors providing detailed maritime information have become available for large offshore areas in real time: maritime radar sensors in the 1950s and the automatic identification system (AIS) in the 1990s among them. However, ground-based maritime radars and AIS data do not always provide a comprehensive and seamless coverage of the entire maritime space. Therefore, the exploitation of space-based sensor technologies installed on satellites orbiting around the Earth, such as satellite AIS data, synthetic aperture radar, optical sensors, and global navigation satellite systems reflectometry, becomes crucial for MS and to complement the existing terrestrial technologies. In the first part of this work, we provide an overview of the main available space-based sensors technologies and present the advantages and limitations of each technology in the scope of MS. The second part, related to artificial intelligence, signal processing and data fusion techniques, is provided in a companion paper, titled: "Space-based Global Maritime Surveillance. Part II: Artificial Intelligence and Data Fusion Techniques" [1].Comment: This paper has been submitted to IEEE Aerospace and Electronic Systems Magazin