Submarine Detection Research Articles

Biologically inspired piezoresistive MEMS acoustic vector sensor for underwater applications

Underwater acoustics has assumed a pivotal role in the detection, navigation, communication, and target identification of ships and submarines. In recent years, advancements in noise reduction from marine vessels have underscored the significance of underwater acoustic vector sensors. This paper presents a novel approach to the design, fabrication, and characterization of a two-dimensional Micro-Electro Mechanical Systems (MEMS) vector acoustic sensor tailored for underwater environments. Traditional underwater acoustic vector sensors often employ doped polysilicon or silicon/germanium sensing films on rigid silicon substrates. The inflexible nature of silicon substrates necessitates labor-intensive and costly chemical-mechanical polishing processes to achieve submicron thickness, often requiring extended clean-room usage. In contrast, this work proposes a simplified, cost-effective, and scalable alternative. The sensor design utilizes reduced graphene oxide (rGO) as the sensing material and Kapton as the substrate, chosen for their unique properties. rGO exhibits high carrier mobility and low intrinsic noise, ensuring clear signals with minimal external interference, thereby improving measurement accuracy in challenging environments. Kapton provides excellent thermal stability, mechanical strength, and chemical resistance, along with superior insulating properties that reduce electrical noise, enhancing the signal-to-noise ratio. The designed vector sensor leverages the piezoresistive transduction principle, incorporating a thin piezoresistive film of rGO on a flexible Kapton substrate via a straightforward drop-casting method. Inspired by the sensory mechanisms of aquatic life, the two-dimensional vector sensor not only detects pressure associated with acoustic signals but also discerns the direction from which these low and ultralow frequency signals originate. The device's performance characteristics, sensitivity, and directivity are comprehensively evaluated through static, dynamic, and acoustic tests conducted in both air and water mediums. Static tests reveal the piezoresistive behavior of rGO under applied displacement, yielding displacement sensitivities of 0.0279 V/mm and 0.0276 V/mm for axial and radial displacements, respectively. Dynamic and acoustic tests demonstrate the sensor's capability to detect low-frequency signals spanning from 0.25 Hz to 200 Hz, exhibiting a smooth and favorable frequency response. In air, the sensor exhibits receiving sensitivities ranging from −15.18 dB to −19.75 dB (X-channel) and −13.67 dB to −16.67 dB (Y-channel). In the underwater environment, these values range from −134.40 dB to −138.93 dB (X-channel) and −131.83 dB to −136.93 dB (Y-channel). Notably, the variation in receiving sensitivity across channels in both air and water is limited to within 6 dB. Furthermore, the device showcases a symmetrical directivity pattern resembling the shape of an "8," with an approximate sensitivity of −136.66 dB, a significant improvement compared to the −165 dB sensitivity of conventional polysilicon underwater vector sensors. These experimental findings affirm the feasibility of the proposed underwater vector sensor, based on the piezoresistive effect and MEMS technology, highlighting its two-dimensional directivity capabilities.

Spatiotemporal Analysis of Sonar Detection Range in Luzon Strait

Sonar serves as a critical submarine detection apparatus for naval vessels, with its detection range forming the foundation of its overall performance in underwater surveillance. The Luzon Strait, in the eastern part of the South China Sea, presents a complex hydrographic setting that profoundly influences sonar performance, necessitating mastery of the detection range variation for enhanced anti-submarine operational efficiency. This study employs the Bellhop acoustic propagation model to estimate the transmission loss. Subsequently, a detection probability integration approach is applied to determine the sonar detection range in the Luzon Strait from 2019 to 2023, which is then subjected to statistical analysis. The findings indicate the following. (1) During the summer and autumn, the shallow mixed layer fails to generate a surface duct, resulting in shorter detection ranges that are primarily dependent on the water depth. In the Shallow Water Zone (<150 m), frequent interactions between sound waves and the sea boundaries lead to considerable acoustic energy attenuation, maintaining a short detection range. In the Intermediate Depth Zone (150–2500 m), sound rays retain adequate energy post-seabed reflection, extending the sonar detection to 5–8 km. Beyond 2500 m, the diminishing reflective energy restricts the range to 2–5 km. (2) Conversely, in the winter and spring, the formation of a surface duct becomes the predominant determinant of the detection range, capable of exceeding 10 km, overshadowing the influence of the water depth.

Modeling and theoretical exploration of free surface manifestation of submarines in presence and absence of ocean waves

Maritime surveillance using remote-sensing images is one of the emerging technologies. Because of the inaccessibility of real-time remote-sensing images, it is imperative to model them. The main intention of this study is to investigate the factors influencing the detection of submarines, irrespective of the imaging sensors. In the present work, submarine wakes (Bernoulli hump and Kelvin wake) are modeled and integrated with the sea surface to examine the key features of the submarine. Here, the sea surface is simulated by linear Airy theory using the Elfouhaily spectrum, and novel submarine position projection in imaging coordinate (SPPIC) technique is introduced to generate synthetic free surface wakes in different orientations. Besides, Computational Fluid Dynamics (CFD) technology is utilized to assess and endorse the SPPIC-based simulated wake models. The Beaufort scale is used to validate the modeled sea surface, and the root mean square error of the model is 0.314 m. Then, the simulated submarine wakes are verified by analyzing its essential features and extracting the significant parameters of submarine, such as moving velocity, heading angle, and diving depth. Further, the current research explores these significant characteristics in the context of ocean waves. The Fourier transform technique is employed to retrieve the heading angle and velocity of the submarine. The introduction of variance distribution in the Radon transform method resolves the 180⁰ ambiguity problem in heading angle calculation. Additionally, negative exponential relation is established between the diving depth of the submarine and the height of the Bernoulli hump. From this empirical equation, one can fetch the diving depth of the submarine. The discrete wavelet transform approach enhances the edges of the wedge Kelvin wake in the presence of sea waves and is demonstrated with real-time synthetic aperture radar images. Moreover, primary wake features are investigated and evaluated for different classes of submarines.

An improvised optimization algorithm for submarine detection in underwater wireless sensor networks

An improvised optimization algorithm for submarine detection in underwater wireless sensor networks

Optimization method of passive omnidirectional buoy array in on-call anti-submarine search based on improved NSGA-II

Passive omni-directional sonar buoys are extensively used as submarine detection devices in anti-submarine UAVs. Studying the problem of optimizing their deployment can effectively enhance their submarine detection capabilities, facilitating further anti-submarine operations. To maximize the search efficiency against quiet submarines during on-call submarine search, an optimization method based on an improved NSGA-II is proposed. First, considering the scenario in which the submarine's speed and approximate heading are known, the initial and postmaneuver position distribution are established. Second, the search efficiency models for a single sonar buoy and for a buoy array are established by the grid method. The effective positioning probability model is established by the LOFIX method. Third, the optimization model of buoy array deployment based on the improved NSGA-II is established with optimization objectives to maximize the submarine search probability and the effective positioning probability and minimize the delivery amount of the buoys. By introducing a probability selection operator, a hybrid crossover operator and an improved elite preservation strategy to enhance the NSGA-II, the global search capability of the algorithm is improved. Finally, the experimental results show that the improved NSGA-II can obtain effective optimal deployment solutions for the buoy array, and the optimal delivery amount and search probability change with changes in the scenario parameters.

Meshfree Interpolation of Multidimensional Time-Varying Scattered Data

Interpolating and approximating scattered scalar and vector data is fundamental in resolving numerous engineering challenges. These methodologies predominantly rely on establishing a triangulated structure within the data domain, typically constrained to the dimensions of 2D or 3D. Subsequently, an interpolation or approximation technique is employed to yield a smooth and coherent outcome. This contribution introduces a meshless methodology founded upon radial basis functions (RBFs). This approach exhibits a nearly dimensionless character, facilitating the interpolation of data evolving over time. Specifically, it enables the interpolation of dispersed spatio-temporally varying data, allowing for interpolation within the space-time domain devoid of the conventional “time-frames”. Meshless methodologies tailored for scattered spatio-temporal data hold applicability across a spectrum of domains, encompassing the interpolation, approximation, and assessment of data originating from various sources, such as buoys, sensor networks, tsunami monitoring instruments, chemical and radiation detectors, vessel and submarine detection systems, weather forecasting models, as well as the compression and visualization of 3D vector fields, among others.

Research on the fluid dynamics interaction between submarine sand waves and seawater by seismic oceanography

IntroductionThe seafloor is an important interface between the lithosphere and the hydrosphere, where processes related to circulation and energy exchange happen along with various marine processes widely developed in the water column near the seafloor. These processes are still not yet completely understood as there are constraints of submarine detection technology and the interdisciplinary nature of these complex environments. Seismic reflection data have been a preferable tool to study and image these processes due to their characteristics in terms of spatial resolution. In seismic reflection data, submarine sand waves show hair-like reflection configurations with low continuity and wearing-hair style, appearing with an angle with the seafloor. Investigation of the relationship between the characteristics of submarine sand waves induced hair-like reflection configuration and hydrodynamics is crucial for understanding hair-like reflection configuration generation and spatiotemporal evolution. MethodsThis study combines fluid dynamics numerical simulation and seismic oceanography to discuss the seismic response characteristics and formation mechanisms of the hair-like reflection configuration. First, we create a seawater time-variant fluid-dynamical model followed by the numerical simulation of seismic oceanography data. This procedure results in seismic oceanography numerical simulation sections with hair-like reflection configurations for different constant flow conditions forced on the boundary. Optimal matching method is then applied to interpret field seismic reflection sections given the results obtained with the numerical experiments. Results and discussionAs consequence, the fluid dynamic explanation for the formation mechanism of the hair-like reflection configuration due to differences in seawater thermohaline is proposed. The study provides additional comprehension and further insights into the dynamic process of submarine sand waves induced hair-like reflection configuration using the seismic oceanography method.

Underwater Formation System Design and Implement for Small Spherical Robots

Aiming at the difficulty of communication and positioning of the existing underwater robot system, this article combines the vision system with a closed leader–follower formation structure to realize the underwater formation of three underwater robots. On account of the long-standing tracking requirements during vision-based formation process, an antiloss and redetecting strategy is fused in the proposed detecting and tracking algorithm and the binocular vision system can achieve real-time positioning underwater and calculate the 3-D coordinate so as to complete the follower's follow-up to the leader. An artificial submarine detection experiment and an antiloss redetection experiment are applied to demonstrate the robustness of the algorithm. And the underwater formation experiment is implemented so that the effectiveness of the proposed vision-based formation strategy is proved, which also provides a new solution for expanded formation system and multilevel cooperation.

Key Technologies and Evaluation of a MiniSAR Experimental System for Unmanned Underwater Vehicle Detection

Synthetic aperture radar (SAR) imaging has important application potential in sea environments research, such as submarine detection. It has become one of the most significant research topics in the current SAR imaging field. In order to promote the development and application of SAR imaging technology, a MiniSAR experiment system is designed and developed, which provides a platform for related technology investigation and verification. A flight experiment is then conducted to detect the movement of an unmanned underwater vehicle (UUV) through the wake, which can be captured by SAR. This paper introduces the basic structure and the performance of the experimental system. The key technologies for Doppler frequency estimation and motion compensation, the implementation of the flight experiment, and the image data processing results are given. The imaging performances are evaluated, and the imaging capabilities of the system are verified. The system provides a good experimental verification platform to construct the follow-up SAR imaging dataset of UUV wake and investigate related digital signal processing algorithms.

Langevin's Ultrasonic Metrology.

This article proposes that Paul Langevin should be considered the originator of ultrasonic metrology. He established the theoretical foundation for the use of radiation pressure for the measurement of acoustic power, by considering the energy density at a target in a beam. This approach was used for calibrating the ultrasonic transducers he helped to develop for submarine detection and underwater communications during the First World War (WWI). Within a decade, he developed two calibrated devices to measure acoustic power and average intensity, a torsion balance, and the first electronic power meter. He patented a piezoelectric non-resonant quartz hydrophone and a quartz probe to explore transducer surface vibration. Design criteria for the instruments included a rugged design that could allow measurements to be carried out not only in the laboratory but also at sea. Langevin was also influential in establishing an ultrasonics transducer laboratory in Toulon in 1923 where these instruments were used. New quartz pulse-echo transducer designs were developed and evaluated there, and performance certification was provided for manufactured transducers for both naval and civil systems. Early workers in ultrasonics recognized Langevin's original and pioneering contributions, which were the enabling technology for modern ultrasonic metrology.

An Improved Wake Vortex-Based Inversion Method for Submarine Maneuvering State.

As the noise reduction performance of submarines continues to improve, it is difficult to detect and track submarines through acoustic detection techniques. Therefore, nonacoustic submarine detection techniques are becoming more and more important. The submarine movement will leave a wake vortex, and the information of the wake vortex can be used to invert the maneuvering state of the submarine. However, the wake vortex is constantly dissipated in the evolution process, and the strength of the wake vortex is constantly reduced, resulting in the gradual weakening of the characteristics of the wake vortex, which makes the inversion of submarine operating state difficult and less accurate. In order to solve the above problems, this paper proposes an improved wake vortex-based inversion method for submarine maneuvering state. Firstly, a random finite set of submarine wake vortex observation features is established to obtain the feature with the highest correlation degree with submarine maneuvering state in the random finite set. Secondly, the multiscale fusion module and attention mechanism are used to re-encode the weak features of the wake vortex image, and the salient features of the wake vortex image are extracted. Finally, the manipulation state of the wake vortex image is retrieved by the extracted salient features. The experimental results show that the average inversion accuracy of the proposed algorithm is improved by 1.27% in terms of manipulating state inversion of weak feature wake vortex images. The algorithm in this paper can realize the inversion of submarine maneuvering state in the case of weak submarine wake vortex image features and incomplete feature information. It provides the basis for the detection technology based on the submarine wake characteristics.

Guest Editorial: Emerging Trends and Challenges in Internet-of-Underwater-Things

Internet-of-Underwater-Things (IoUT) is a network of smart interconnected underwater objects. Recently, IoUT has shown its applicability in numerous scenarios such as marine life monitoring, off-shore exploration, underwater lost-treasure discovery, sports, assisted navigation, location awareness, environmental monitoring (e.g., monitoring of water quality, water pollution, water pressure or water temperature), water-based disasters (e.g., tsunami or nuclear accident), defense systems (e.g., surveillance systems or submarine detection) and several other applications. Even though IoUT systems are key enabler in underwater communication, they face challenges due to unreliable transmission medium, unstable radio signals, limited range, low bandwidth, inborn noise, low transmission rate, slow propagation speed, node mobility, lower resources and limited battery capacity. These challenges cause issues in channel modeling, optimal routing, security, privacy, communication overhead, congestion control, packet error rate, packet latency, energy consumption etc. In this respect, this Special Issue (SI) aims to address some of the aforementioned challenges.

Opportunity Based Energy Efficient Routing Algorithm for Underwater Wireless Sensor Network for Submarine Detection

The submarine detection is the most significant research area of Under Water Acoustic (UWA) environment with extensive application in commercial and navy domains. The environmental complexity and variable nature of the UWA makes Underwater Wireless Sensor Network (UWSN) to exhibit fluidity, sparse deployment, time unpredictability, frequency selectivity, limited accessible bandwidth and energy constraints pose problems in the underwater positioning technology. Thus, an adaptable, scalable, and highly efficient UWA is required for the submarine routing systems. The depth-based routing has received lots of interest as it is capable of delivering effective operation without requiring full-dimensional position information of nodes. However, it has issues of vacant regions and detouring forwards. To delineate the aforementioned problems, this paper proposes an Opportunity-based Distance Vector Routing (ODVR) technique. The distance vectors, which have lowest hop counts in the direction of sink for underwater sensor nodes are determined by ODVR through a query method. Depending on the distance vectors, a dynamic routing is created to manage the packet forwarding. In the opportunistic forwarding, the ODVR has a minimal signaling cost and minimum energy consumption with the potential of eliminating the long detours issues. The outcomes of simulations demonstrate that the ODVR outperforms the conventional routing algorithms.

BDREA Betta and Dolphin Pods Routing via Energy Scarcity Aware Protocol for Underwater Acoustic Wireless Sensor Networks (UAWSNs)

There exist numerous applications for deploying Underwater Wireless Sensor Networks (UWSNs), including submarine detection, disaster prevention, oil and gas monitoring, off-shore exploration, and military target tracking. The acoustic sensor nodes are deployed to monitor the underwater environment, considering the area under observation. This research work proposes an energy scarcity-aware routing protocol for energy efficient UWSNs. Moreover, it aims to find the feasible region on the basis of the objective function, in order to minimize the energy tax and extend the network life. There are three different sensors nodes in the network environment, i.e., anchor nodes, relay nodes, and the centralized station. Anchor nodes originate data packets, while relay nodes process them and broadcast between each other until the packets reach the centralized station. The underline base scheme Weighting Depth and Forwarding Area Division Depth-Based Routing (WDFAD-DBR) for routing is based on the depth differences of the first- and second-hop nodes of the source node. The propose work, Betta and Dolphin Pods Routing via Energy Scarcity Aware protocol (BDREA) for packet forwarding from the forwarding nodes considers the first and second hops of the source node, i.e., the packet advancement, the network traffic, the distance to the centralized station, and the inverse normalized energy of the forwarding zone. It is observed that the proposed work improves the performance parameters by approximately 50% in terms of energy efficiency, and prolongs the network life compared to Dolphin and Whale Pod (DOW-PR) protocols. Furthermore, the energy efficiency directly relates to the other parameters, and its enhancement can be seen in terms of an 18.02% reduction in end-to-end delay when compared with the Weighting Depth and Forwarding Area Division Depth-Based Routing (WDFAD-DBR) protocol. Furthermore, BDREA improves the Packet Delivery Ratio (PDR) by approximately 8.71%, compared to DOW-PR, and by 10% compared with the benchmark, WDFAD-DBR, the energy tax by 50% in comparison to DOW-PR, the end-to-end delay by 18%, and the APD by 5% in comparison to WDFAD-DBR.

Free surface features of submarines moving underwater: Study of Bernoulli Hump

Submarines are known to produce certain surface manifestations, primary among them being a feature known as Bernoulli Hump (BH). BH is a rise and fall of sea surface height above the submarine, when the vessel cruises close to surface. This feature has been noted by many researchers but scant information is publically available on the same due to the classified nature of the data. A major part of the Wide Area Surveillance program for submarines of the world navies uses the detection of this BH. In this work, our objective is to detect and establish the presence of BH characteristics. After calibrating a known CFD code using experimental data, we make model simulations which clearly depict the BH and its features. We then show the path ahead for submarine detection using BH from observations of sea surface heights. Value of BH height for a submarine at 10m depth moving at 5 knots is about 20cm which falls within the 2 cm vertical resolution of altimeters. Though most of the studies were for calm waters, an introduction to the presence of regular wind waves is given at the end.

Theoretical Investigation on the Linear Location Algorithm of the Magnetic Gradient Tensor Ranging by Use of Cuboid Triaxial Magnetometer Array

The passive magnetic detection and localization technology of the magnetic field has the advantages of good concealment, continuous detection, high efficiency, reliable use, and rapid response. It has important application in the detection and localization of submarines and mines. The conventional location algorithm needs magnetic gradient tensor system moving to other points, we propose a kind of linear location algorithm with a unique solution based on a single measurement of the cuboid tri-axial magnetometer array. The magnetic gradient tensor of the magnetic target is first calculated at the center points of the six rectangles of the cuboid array, and then the distance between the magnetic target and the rectangle center of the cuboid array is calculated. Finally, according to the square difference of the distances of the three pairs of parallel rectangles, a linear equation set about the position coordinates of the magnetic dipole is formed and then these position coordinates are calculated fast. We derive an analytical formula of the location error for the linear location algorithm. The simulation shows that the position of the target can be calculated accurately and the relative error of the position is <1%, and the location errors are positively correlated with the noise standard deviation of the three-axis magnetometer, and more they are proportional to the non-orthogonality between every two axes, sensitivity deviation and bias of the three-axis magnetometer. The location errors of the linear location algorithm through numerical simulations are consistent with the location errors calculated by the analytical formula.

Submarine Cable Detection Method Based on Multisensor Communication

Submarine cable is widely used in today’s oil industry, and it is a much hidden large‐scale industrial facility, which vigorously promotes the development of people’s lives. With the widespread use of submarine cables based on multisensor communication, as far as the current situation is concerned, this paper makes a report and summary on the research of submarine cable detection method in shallow sea area (sea area within 200 m). According to the implementation of the project and the way of controlling variables, the current common detection modes are planned, fault prediction, fault diagnosis, fault analysis and summary, and experimental data comparison, and then, we can use Brillouin radio frequency to prevent the occurrence of submarine cable fault, and when the fault occurs, we can detect the fault at the first time. The feedback value range of TTSL electromagnetic detection is very stable, and the Brillouin scattering frequency is within the normal fluctuation range. In deep‐sea exploration, TTSL electromagnetic detection can detect faults for submarine cables and will not affect the fault in all aspects of waveform and wavelength. Finally, the best path and future development trend of submarine cable detection method are obtained by analyzing and summarizing the detection data, and a complete scheme plan such as some preventive measures and repair technology is put forward.

Последние тенденции в развитии подводной беспроводной сенсорной сети: систематический обзор литературы

Underwater Wireless Sensor Networks (UWSNs) is an emerging technology for the monitoring of aquatic assets and frequently applied in several domains like underwater information gathering, ocean sampling network, anonymous vehicles, disaster prevention and submarine detection. Recently, UWSNs have been getting significant attention of researchers from both academia and industry. As a result, several studies have been carried out to perform certain improvements in UWSNs techniques, tools, protocols and architectures. In this regard, there is a dire need to investigate and summarize the modern UWSNs trends altogether within a single study. To achieve this, a Systematic Literature Review (SLR) is performed in this article to comprehensively analyze the latest developments in UWSNs. Particularly, 34 research studies published during 2012-2020 have been selected and examined in the area of UWSNs. This leads to the identification of 21 modern routing protocols and 11 tools. Furthermore, 5 different architecture types and 3 communication media technologies are presented in the context of UWSNs. Finally, a comparative analysis of routing protocols is done on the basis of important evaluation metrics. It has been concluded that there exist adequate approaches, protocols and tools for the monitoring of UWSNs. However, the design verification capabilities of existing approaches are insufficient to meet the growing demands of UWSNs. The findings of this article provide solid platform to enhance the current UWSNs tools and techniques for large and complex networks.

Recent Trends in Underwater Wireless Sensor Networks (UWSNs) – A Systematic Literature Review

Underwater Wireless Sensor Networks (UWSNs) is an emerging technology for the monitoring of aquatic assets and frequently applied in several domains like underwater information gathering, ocean sampling network, anonymous vehicles, disaster prevention and submarine detection. Recently, UWSNs have been getting significant attention of researchers from both academia and industry. As a result, several studies have been carried out to perform certain improvements in UWSNs techniques, tools, protocols and architectures. In this regard, there is a dire need to investigate and summarize the modern UWSNs trends altogether within a single study. To achieve this, a Systematic Literature Review (SLR) is performed in this article to comprehensively analyze the latest developments in UWSNs. Particularly, 34 research studies published during 2012-2020 have been selected and examined in the area of UWSNs. This leads to the identification of 21 modern routing protocols and 11 tools. Furthermore, 5 different architecture types and 3 communication media technologies are presented in the context of UWSNs. Finally, a comparative analysis of routing protocols is done on the basis of important evaluation metrics. It has been concluded that there exist adequate approaches, protocols and tools for the monitoring of UWSNs. However, the design verification capabilities of existing approaches are insufficient to meet the growing demands of UWSNs. In this context, the findings of this article provide solid platform to enhance the current UWSNs tools and techniques for large and complex networks.

Acoustically measured transmission loss improves effectiveness of sonar search

The Sonar Equation is the heart of the process for predicting the effectiveness of an Antisubmarine Warfare (ASW) ship's sonar in the underwater detection of submarines. The equation's determination of Ranges associated with probabilities of detection and false alarms is the fundamental input for the selection of the most effective sonar modes in an individual ship and, at the broader tactical scale, in the selection of ASW search plans. The Sonar Equation's predictions of sonar performance, however, are subject to considerable error when employed tactically at sea in ASW operations. A major source of the error is the input, Transmission Loss, usually derived from XBT “snapshots” of temperature versus water depth. The resulting predictions of sonar performance are projected uniformly over space and time, leading to predictions that are stale and inaccurate. Accuracy of the Sonar Equation's output, however, can be improved by measuring Transmission Loss acoustically and continuously. A stream of pulses, periodically broadcast from a specially designed expendable sound source, is measured at the front end of the ship's sonar. A large population of Transmission Loss values is built up from which strong statistical inferences regarding detection can be drawn. The power of a continuously updated population of Transmission Loss values leads to more accurate inferences of the local acoustic environment.