The fractional Fourier transform (FrFT) provides a valuable tool for the analysis of linear chirp signals. This paper develops two short-time FrFT variants which are suited to multicomponent and nonlinear Outputs have similar properties (STFT) but show improved time-frequency resolution. is parameterized with parameter, a, related rate. implementations differ in how value chosen. In first, global optimization procedure selects one reference entire signal. second, values selected...

This paper proposes a semantic world model framework for hierarchical distributed representation of knowledge in autonomous underwater systems. aims to provide more capable and holistic system, involving interoperability among all involved information sources. will enhance interoperability, independence operation, situation awareness the embedded service-oriented agents platforms. The results obtained specifically affect mission flexibility, robustness, autonomy. presented makes use idea...

This paper uses advanced time-frequency signal analysis techniques to generate new models for bio-inspired sonar signals. The inspiration comes from the of bottlenose dolphin clicks. These pulses are very short duration, between 50 and 80μs, but certain examples we can delineate a double down-chirp structure using fractional Fourier methods. majority clicks have energy distributed two main frequency bands with higher frequencies delayed in time by 5–20μs. Signal syntheses multiple chirp...

The fractional Fourier transform (FrFT) provides an important extension to conventional theory for the analysis and synthesis of linear chirp signals. It is a parameterised which can be used provide extremely compact representations. representation maximally compressed when parameter, α, matched rate input signal. Existing proofs are extended demonstrate that Gaussian function also has support. Furthermore, expressions developed allow calculation spread signal windowed in any domain. Both...

To date most sonars use narrow band pulses and often only the echo envelope is used for object detection classification. This paper considers advantages afforded by bio-inspired sonar identification classification through analysis understanding of broadband structure. Using biomimetic dolphin based system in conjunction with developed from observations bottlenose dolphins performing tasks, results are presented experiments carried out a wave tank harbor. In these responses various targets to...

Multiple-input-multiple-output (MIMO) sonar systems offer new perspectives for target detection and area surveillance. This paper introduces a unified formulation MIMO focuses on the recognition capability of these systems. The multiplication number transmitters receivers not only provides greater variety in terms view angles but also meaningful statistics itself. Assuming that views are independent system is large enough, we demonstrate possible with one snapshot. By studying performance...

Subsea power cables are critical assets for electrical transmission and distribution networks, highly relevant to regional, national, international energy security decarbonization given the growth in offshore renewable generation. Existing condition monitoring techniques restricted constrained online systems that only prioritize internal failure modes, representing 30% of cable mechanisms, has limited capacity provide precursor indicators such failures or damages. To overcome these...

A survey is given covering synchronization techniques for large-capacity time-division multiple-access (TDMA) systems using geosynchronous satellites. Five important classes are identified and compared. Also, several methods of initial acquisition described. The fundamentals multiple access TDMA in particular presented. Summary descriptions comparisions the developed to date experimental, prototype, operational systems. Some related technologies introduced. It concluded that a maturing period.

Abstract The architecture of an advanced fault detection and diagnosis (FDD) system is described applied with Autonomous Underwater Vehicle (AUV). aims to provide a more capable that does not require dedicated sensors for each fault, can diagnose previously unforeseen failures cause‐effect patterns across different subsystems. It also lays the foundations incipient condition‐based maintenance schemes. A model relationships used as ontology describe connected set electrical, mechanical,...

This article demonstrates, through finite element analysis, the possibility to manufacture sub-30 nm polymeric channels using electrostatic induced lithography. Channels with a width of 25 nm, depth 50 and an inter-channel wall 28 can be obtained by this patterning process. The influence operational parameters such as filling factor, aspect ratio master electrode, applied voltage gap between two electrodes initial film thickness has been studied in detail define fabrication limits process...

Convolutional Neural Networks (CNNs) are a popular choice for estimating Direction of Arrival (DoA) without explicitly delays between multiple microphones. The CNN method first optimises unknown filter weights (of CNN) by using observations and ground-truth directional information. This trained is then used to predict incident directions given test observations. Most existing methods train spectrally-flat random signals speech. In this paper, which focuses on single source DoA estimation, we...

New generations of sonars appeared in the last decade. The major interest SAS systems and high frequency is improvement sonar resolution reduction noise level. Sonar images are distance-images but at they tends to appear visually as optical images. Usually algorithms developed for sidescan were specific due poor essentially. With sonars, image processing field natural became applicable. In this paper we present a real-time realistic simulator, test image-based classification (such PCA...

This work introduces a low-cost energy measurement method and proposes simple linear model to estimate the vehicle consumption when navigating given trajectory. Experimental results on Nessie VII AUV show that developed system can be used measure during vehicle's operations with good confidence level. Moreover proposed estimation trained using calibration procedure each time environmental conditions change or configuration is altered. The solution suited real-time use low-power embedded...

The need for embedding fault diagnosis into goal-orientated autonomous robotic vehicles increased mission robustness is described. RECOVERY system, a method increasing the diagnostic capability by integrating commonly available heterogeneous knowledge presented. Initial real-water results using Ocean Systems Laboratory's RAUVER vehicle are given.

The Ocean Systems Laboratory is developing bio-inspired wideband acoustic sensing methods for underwater target detection and tracking. sensors themselves are based on bottlenose dolphin sonar, covering a frequency band from around 30kHz to 150kHz having dependent beamwidth considerably larger than conventional imaging sonars. entire system relatively compact suitable mounting variety of platforms including small scale autonomous vehicles (AUVs). In this paper we overview recent efforts...

This paper presents classification of spherical objects with different physical properties. The is based on the energy distribution in wideband pulses that have been scattered from objects. echo represented Time-Frequency Domain (TFD), using Short Time Fourier Transform (STFT) window lengths, and fed into a Convolution Neural Network (CNN) for classification. results lengths are analysed to study influence time frequency resolution CNN performs best accuracy (98.44 ± 0.8)% over 5 object...

Recent developments in defining ontologies for a domain provide significant potential model design, able to encapsulate the essence of diagnostic semantic into concepts and describe key relationships between components system being diagnosed. In this paper, framework based on knowledge space is developed guide fault detection process better automated discovery improve diagnostics. The approach applied pneumatic door rolling stock vehicle. This article describes capabilities proposed...

Marine mammals have developed highly effective sonar systems for detecting, identifying, and following underwater objects. In this paper we demonstrate that bio-inspired wideband offers great capability tracking cables on the seafloor. The analysis of biological signals, including dolphin clicks, suggests two approaches. first is to use a signal, integrating response an object over many frequencies. For simple forms, known give access shape material information. second idea intelligent...

The sonar of dolphins has developed over millions years evolution and achieved excellent performance levels. Using the as an inspiration, bio-inspired wideband acoustic sensing methods for underwater target detection tracking are being developed. In this study authors explore what they expect to gain from such a sonar. systems sensors based on bottlenose sonar, covering frequency band around 30 150 kHz having dependent beamwidth considerably larger than that conventional imaging sonars....

Inspection of masonry buildings, typically railway bridges, for crack detection is currently performed by humans under tedious and sometimes dangerous working conditions. Over the past years, computer vision based techniques have been developed to automate structure visual inspections. These could be integrated with (semi) autonomous drone surveillance collect images assets full automation simultaneous inspection in bridges. In this study we adopted architecture Faster R-CNN object detectors...

This paper is focused on improving the self-awareness of autonomous underwater vehicles (AUVs) operating in unknown environments. A runtime estimation framework introduced to derive energy usage and navigation performance metrics presence external disturbances, such as slowly varying sea currents. These are calculated by a state-of-the-art nonlinear regression algorithm (LWPR) using measurements commonly available on-board modern AUVs without relying sensors or priori knowledge about...