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22 pages, 18001 KiB

Open AccessArticle

A Triggering Mechanism for Cyber-Attacks in Naval Sensors and Systems

by Walmor Cristino Leite Junior, Claudio Coreixas de Moraes, Carlos E. P. de Albuquerque, Raphael Carlos Santos Machado and Alan Oliveira de Sá

Sensors 2021, 21(9), 3195; https://doi.org/10.3390/s21093195 - 04 May 2021

Cited by 16 | Viewed by 4569

Abstract

In the maritime sector, the integration of radar systems, Automatic Identification System (AIS) and Electronic Chart Display and Information System (ECDIS) through digital technologies enables several benefits to maritime operations, but also make ships prone to cyberattacks. In this context, this work investigates [...] Read more.

In the maritime sector, the integration of radar systems, Automatic Identification System (AIS) and Electronic Chart Display and Information System (ECDIS) through digital technologies enables several benefits to maritime operations, but also make ships prone to cyberattacks. In this context, this work investigates the feasibility of an attacker using a radar system or AIS as open door to remotely send commands to a cyber threat hosted on a ship, even if the ship’s systems are air gapped—i.e., are not connected to other networks. The received commands are intended to trigger a cyber threat located in the ship. Although the literature covers several analyzes on cyber risks and vulnerabilities in naval systems, it lacks exploiting mechanisms capable of acknowledging attack commands received through radar and AIS. To this end, this work proposes a triggering mechanism that uses a template matching technique to detect specific patterns transmitted by the attacker to the ship’s radar or AIS. The results show the effectiveness of the proposed technique as a tool to acknowledge the received attack commands and activate a malicious code previously installed on the ship. In the case of attacks on a radar system, the accuracy achieved by the proposed method is 0.90. In the case of attacks on an AIS/ECDIS setup it presents an accuracy of 0.93. In both cases the proposed mechanism maintains the due safety against accidental attack activations. Full article

(This article belongs to the Special Issue Selected Papers from the 2020 IMEKO TC-19 International Workshop on Metrology for the Sea)

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23 pages, 11574 KiB

Open AccessArticle

Semi-Automated Data Processing and Semi-Supervised Machine Learning for the Detection and Classification of Water-Column Fish Schools and Gas Seeps with a Multibeam Echosounder

by Annalisa Minelli, Anna Nora Tassetti, Briony Hutton, Gerardo N. Pezzuti Cozzolino, Toby Jarvis and Gianna Fabi

Sensors 2021, 21(9), 2999; https://doi.org/10.3390/s21092999 - 24 Apr 2021

Cited by 10 | Viewed by 4450

Abstract

Multibeam echosounders are widely used for 3D bathymetric mapping, and increasingly for water column studies. However, they rapidly collect huge volumes of data, which poses a challenge for water column data processing that is often still manual and time-consuming, or affected by low [...] Read more.

Multibeam echosounders are widely used for 3D bathymetric mapping, and increasingly for water column studies. However, they rapidly collect huge volumes of data, which poses a challenge for water column data processing that is often still manual and time-consuming, or affected by low efficiency and high false detection rates if automated. This research describes a comprehensive and reproducible workflow that improves efficiency and reliability of target detection and classification, by calculating metrics for target cross-sections using a commercial software before feeding into a feature-based semi-supervised machine learning framework. The method is tested with data collected from an uncalibrated multibeam echosounder around an offshore gas platform in the Adriatic Sea. It resulted in more-efficient target detection, and, although uncertainties regarding user labelled training data need to be underlined, an accuracy of 98% in target classification was reached by using a final pre-trained stacking ensemble model. Full article

(This article belongs to the Special Issue Selected Papers from the 2020 IMEKO TC-19 International Workshop on Metrology for the Sea)

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18 pages, 5734 KiB

Open AccessArticle

Investigation on Spectrum Estimation Methods for Bimodal Sea State Conditions

by Giovanni Battista Rossi, Francesco Crenna, Marta Berardengo, Vincenzo Piscopo and Antonio Scamardella

Sensors 2021, 21(9), 2995; https://doi.org/10.3390/s21092995 - 24 Apr 2021

Cited by 12 | Viewed by 1760

Abstract

The reliable monitoring of sea state parameters is a key factor for weather forecasting, as well as for ensuring the safety and navigation of ships. In the current analysis, two spectrum estimation techniques, based on the Welch and Thomson methods, were applied to [...] Read more.

The reliable monitoring of sea state parameters is a key factor for weather forecasting, as well as for ensuring the safety and navigation of ships. In the current analysis, two spectrum estimation techniques, based on the Welch and Thomson methods, were applied to a set of random wave signals generated from a theoretical wave spectrum obtained by combining wind sea and swell components with the same prevailing direction but different combinations of significant wave heights, peak periods, and peak enhancement factors. A wide benchmark study was performed to systematically apply and compare the two spectrum estimation methods. In this respect, different combinations of wind sea spectra, corresponding to four grades of the Douglas Scale, were combined with three swell spectra corresponding to different swell categories. The main aim of the benchmark study was to systematically investigate the effectiveness of the Welch and Thomson methods in terms of spectrum restitution and the assessment of sea state parameters. The spectrum estimation methods were applied to random wave signals with different durations, namely 600 s (short) and 3600 s (long), to investigate how the record length affected the assembled sea state parameters, which, in turn, were assessed by the nonlinear least square method. Finally, based on the main outcomes of the benchmark study, some suggestions are provided to select the most suitable spectrum reconstruction method and increase the effectiveness of the assembled sea state parameters. Full article

(This article belongs to the Special Issue Selected Papers from the 2020 IMEKO TC-19 International Workshop on Metrology for the Sea)

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18 pages, 8772 KiB

Open AccessArticle

A Synergic Integration of AIS Data and SAR Imagery to Monitor Fisheries and Detect Suspicious Activities

by Alessandro Galdelli, Adriano Mancini, Carmen Ferrà and Anna Nora Tassetti

Sensors 2021, 21(8), 2756; https://doi.org/10.3390/s21082756 - 13 Apr 2021

Cited by 16 | Viewed by 4456

Abstract

Maritime traffic and fishing activities have accelerated considerably over the last decade, with a consequent impact on the environment and marine resources. Meanwhile, a growing number of ship-reporting technologies and remote-sensing systems are generating an overwhelming amount of spatio-temporal and geographically distributed data [...] Read more.

Maritime traffic and fishing activities have accelerated considerably over the last decade, with a consequent impact on the environment and marine resources. Meanwhile, a growing number of ship-reporting technologies and remote-sensing systems are generating an overwhelming amount of spatio-temporal and geographically distributed data related to large-scale vessels and their movements. Individual technologies have distinct limitations but, when combined, can provide a better view of what is happening at sea, lead to effectively monitor fishing activities, and help tackle the investigations of suspicious behaviors in close proximity of managed areas. The paper integrates non-cooperative Synthetic Aperture Radar (SAR) Sentinel-1 images and cooperative Automatic Identification System (AIS) data, by proposing two types of associations: (i) point-to-point and (ii) point-to-line. They allow the fusion of ship positions and highlight “suspicious” AIS data gaps in close proximity of managed areas that can be further investigated only once the vessel—and the gear it adopts—is known. This is addressed by a machine-learning approach based on the Fast Fourier Transform that classifies single sea trips. The approach is tested on a case study in the central Adriatic Sea, automatically reporting AIS-SAR associations and seeking ships that are not broadcasting their positions (intentionally or not). Results allow the discrimination of collaborative and non-collaborative ships, playing a key role in detecting potential suspect behaviors especially in close proximity of managed areas. Full article

(This article belongs to the Special Issue Selected Papers from the 2020 IMEKO TC-19 International Workshop on Metrology for the Sea)

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19 pages, 6520 KiB

Open AccessArticle

Observation Quality Assessment and Performance of GNSS Standalone Positioning with Code Pseudoranges of Dual-Frequency Android Smartphones

by Umberto Robustelli, Jacek Paziewski and Giovanni Pugliano

Sensors 2021, 21(6), 2125; https://doi.org/10.3390/s21062125 - 18 Mar 2021

Cited by 35 | Viewed by 3809

Abstract

The new generation of Android smartphones is equipped with GNSS chips capable of tracking multi-frequency and multi-constellation data. In this work, we evaluate the positioning performance and analyze the quality of observations collected by three recent smartphones, namely Xiaomi Mi 8, Xiaomi Mi [...] Read more.

The new generation of Android smartphones is equipped with GNSS chips capable of tracking multi-frequency and multi-constellation data. In this work, we evaluate the positioning performance and analyze the quality of observations collected by three recent smartphones, namely Xiaomi Mi 8, Xiaomi Mi 9, and Huawei P30 pro that take advantage of such chips. The analysis of the GNSS observation quality implies that the commonly employed elevation-dependent function is not optimal for smartphone GNSS observation weighting and suggests an application of the

C / N_{0}

-dependent one. Regarding smartphone code signals on L5 and E5a frequency bands, we found that they are characterized with noticeably lower noise as compared to E1 and L1 ones. The single point positioning results confirm an improvement in the performance when the weights are a function of the

C / N_{0}

-rather than those dependent on the satellite elevation and that a smartphone positioning with E5a code observations significantly outperforms that with E1 signals. The latter is expressed by a drop of the horizontal RMS from 8.44 m to 3.17 m for Galileo E1 and E5a solutions of Xiaomi Mi 9 P30, respectively. The best positioning accuracy of multi-GNSS single-frequency (L1/E1/B1/G1) solution was obtained by Huawei P30 with a horizontal RMS of 3.24 m. Xiaomi Mi 8 and Xiaomi Mi 9 show a horizontal RMS error of 4.14 m and 4.90 m, respectively. Full article

(This article belongs to the Special Issue Selected Papers from the 2020 IMEKO TC-19 International Workshop on Metrology for the Sea)

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18 pages, 5302 KiB

Open AccessArticle

Design and Performance Evaluation of a “Fixed-Point” Spar Buoy Equipped with a Piezoelectric Energy Harvesting Unit for Floating Near-Shore Applications

by Damiano Alizzio, Marco Bonfanti, Nicola Donato, Carla Faraci, Giovanni Maria Grasso, Fabio Lo Savio, Roberto Montanini and Antonino Quattrocchi

Sensors 2021, 21(5), 1912; https://doi.org/10.3390/s21051912 - 09 Mar 2021

Cited by 5 | Viewed by 2263

Abstract

In the present work, a spar-buoy scaled model was designed and built through a “Lab-on-Sea” unit, equipped with an energy harvesting system. Such a system is based on deformable bands, which are loyal to the unit, to convert wave motion energy into electricity [...] Read more.

In the present work, a spar-buoy scaled model was designed and built through a “Lab-on-Sea” unit, equipped with an energy harvesting system. Such a system is based on deformable bands, which are loyal to the unit, to convert wave motion energy into electricity by means of piezo patch transducers. In a preliminary stage, the scaled model, suitable for tests in a controlled ripples-type wave motion channel, was tested in order to verify the “fixed-point” assumption in pitch and roll motions and, consequently, to optimize energy harvesting. A special type of structure was designed, numerically simulated, and experimentally verified. The proposed solution represents an advantageous compromise between the lightness of the used materials and the amount of recoverable energy. The energy, which was obtained from the piezo patch transducers during the simulations in the laboratory, was found to be enough to self-sustain the feasible on-board sensors and the remote data transmission system. Full article

(This article belongs to the Special Issue Selected Papers from the 2020 IMEKO TC-19 International Workshop on Metrology for the Sea)

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19 pages, 7196 KiB

Open AccessArticle

Preliminary Study for AUV: Longitudinal Stabilization Method Based on Takagi-Sugeno Fuzzy Inference System

by Enrico Petritoli, Cipriano Bartoletti and Fabio Leccese

Sensors 2021, 21(5), 1866; https://doi.org/10.3390/s21051866 - 07 Mar 2021

Cited by 6 | Viewed by 1753

Abstract

The paper shows the steps for the preliminary studies of an AUV for shallow water: the first part illustrates the vehicle architecture and the philosophy that permeates the various design choices. In the second part illustrates an innovative method for increasing longitudinal stability [...] Read more.

The paper shows the steps for the preliminary studies of an AUV for shallow water: the first part illustrates the vehicle architecture and the philosophy that permeates the various design choices. In the second part illustrates an innovative method for increasing longitudinal stability based on Takagi-Sugeno (T-S) Fuzzy Inference System: it saves a lot of computational time and, by simplifying the calculation, it is also suitable for remarkably simple computers such as Arduino. in the third part is simulated the behavior of the AUV: thanks to the data taken from the previous hydrodynamic simulation, we can establish the behavior of its longitudinal stability and the computational savings due to the T-S method. Full article

(This article belongs to the Special Issue Selected Papers from the 2020 IMEKO TC-19 International Workshop on Metrology for the Sea)

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20 pages, 4711 KiB

Open AccessArticle

DANAE⁺⁺: A Smart Approach for Denoising Underwater Attitude Estimation

by Paolo Russo, Fabiana Di Ciaccio and Salvatore Troisi

Sensors 2021, 21(4), 1526; https://doi.org/10.3390/s21041526 - 22 Feb 2021

Cited by 4 | Viewed by 2513

Abstract

One of the main issues for the navigation of underwater robots consists in accurate vehicle positioning, which heavily depends on the orientation estimation phase. The systems employed to this end are affected by different noise typologies, mainly related to the sensors and to [...] Read more.

One of the main issues for the navigation of underwater robots consists in accurate vehicle positioning, which heavily depends on the orientation estimation phase. The systems employed to this end are affected by different noise typologies, mainly related to the sensors and to the irregular noise of the underwater environment. Filtering algorithms can reduce their effect if opportunely configured, but this process usually requires fine techniques and time. This paper presents DANAE

^{+ +}

, an improved denoising autoencoder based on DANAE (deep Denoising AutoeNcoder for Attitude Estimation), which is able to recover Kalman Filter (KF) IMU/AHRS orientation estimations from any kind of noise, independently of its nature. This deep learning-based architecture already proved to be robust and reliable, but in its enhanced implementation significant improvements are obtained in terms of both results and performance. In fact, DANAE

^{+ +}

is able to denoise the three angles describing the attitude at the same time, and that is verified also using the estimations provided by an extended KF. Further tests could make this method suitable for real-time applications in navigation tasks. Full article

(This article belongs to the Special Issue Selected Papers from the 2020 IMEKO TC-19 International Workshop on Metrology for the Sea)

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