Underwater Cables Research Articles

Making Underwater Cables SMART with Sensors

Future cables that stretch across the ocean, transmitting cat videos and financial transactions, could also contain temperature, pressure, and seismic sensors that would allow scientists to spy on the seafloor.

Analytical modeling of cross-ply cylindrical composite submersible shell with elastic buckling using first order shear deformation theory

The main objective of this study is to design composite shells i.e. long, short, thin and thick for the different underwater applications. These shells can be a part of pressure hulls, underwater vehicles, pressurized tanks, underwater cables and underwater pipelines etc. This paper presents comprehensive procedures for the mathematical modeling of elastic buckling for submersible composite shells under hydrostatic pressure. First order shear deformation theory (FOSDT) was used for modeling. FOSDT theory was mathematically derived under hydrostatic pressure for composite shells, and it can be used for all types of submersible shells. After the derivation of the theory, mathematical code was formed on MATLAB for this modeling. From the given formulation one can design the shell structure according to his needs on different environment conditions. Different types of composite shells, including moderately thick, thick, long, and short, are investigated for the FOSDT formulation to check the accuracy range. The results were compared with previous studies and finite element analysis FEA. Three types of materials, Carbon/Epoxy, Glass/Epoxy, and Boron/Epoxy, were used with different cross-ply symmetric and unsymmetrical angle configurations. The layups used for the analysis were [0/90/0]s [90/0/90/0]s [02/902]s [90/02/90]s [0/902/0]s [0/0/0/90]s [90/90/90/0]s and [0/90].

MiniLab - Agile underwater platform with integrated sensors for environmental and visual applications

The Fraunhofer “Smart Ocean Technologies” (SOT) research team extends its range of services towards underwater technology by developing new internal infrastructure. To test sensor technology and materials, empirical underwater data is required to evaluate new technology within realistic conditions. Various external factors like swell, wind, and the underwater environment itself complicate stable framework conditions during the measurements. For this purpose, a test platform called MiniLab was developed which can be extended by modules with respect to common interfaces. It serves as a base frame for internal as well as external projects. The MiniLab consists of an underwater unit and an on-ground unit. Both are connected via a hybrid underwater cable. In addition to the environmental conditions, camera live streams can be transmitted. The MiniLab service platform is currently being used in the Warnow River and in the Digital Ocean Lab (DOL) in the Baltic Sea. However, it is available for observations in other waters (Fraunhofer, 2021a).

Multicriteria Decision Approach to the Design of Floating Wind Farm Export Cables

This paper addresses subsea electric cable routing using the application of decision support systems combined with the experts’ knowledge. The methodology is successfully applied to a case study on the Spanish coast. The ranking method calculates the multiple criteria weights, and the weighted product method determines the most suitable space. The environmental criteria, with a weight of 61.4%, exceed the significance of other essential criteria in the study based on experts’ considerations. These rankings are input into the model to extract the suitable spaces to deploy the underwater cable. The final result accurately highlights an optimal route in alignment with the experts’ preferences.

On-line status monitoring and surrounding environment perception of an underwater cable based on the phase-locked Φ-OTDR sensing system.

A newly designed phase-locked (PL) Φ-OTDR system was proposed and instrumented. Field tests of water impact, anchor damage towing and tide diagnosing were carried out in a natural freshwater lake as well as the East China Sea. Personnel movement trajectory monitoring and ship flow monitoring were carried out by a buried cable along the floodplain of the Yangtze River. It proved that the proposed system can monitor the real-time status and sense the surrounding environment of existing underwater communication cables, which could be helpful for the maintenance of the cable itself as well as underwater information collection.

DEVELOPMENT OF AUTONOMOUS UNDERWATER VEHICLE (AUV) BASED ON ROBOTIC OPERATING SYSTEM FOR FOLLOWING UNDERWATER CABLE

In addition to satellites, the Marine Cable Communication Channel (SKKL) which is located under the sea is also one of the backbones of the communication network to connect from one island to another. However, there are often irresponsible parties who damage or commit acts of vandalism. This action resulted in the disruption of the communication process on the submarine cable network. So, it is necessary to periodically check the condition of the underwater communication network cables. Regular checking of underwater cables is very risky, so we propose an underwater robot to handle it. This paper presents the development of Autonomous Underwater Vehicle (AUV) based on Robotic Operating System (ROS) for Following Underwater Cable to monitor the condition of the cables automatically. The AUV is equipped with a camera, Nvidia Jetson Nano, Arduino, Flight Controller, ESC, and brushless DC motors that used to assist the tracking process on the cable. The camera is used as the main visual sensor. Visual image processing methods are carried out using thresholding and contours detection methods, then the obtained data are processed to drive the motors on the AUV so that they can move on the direction of the cable. The experiment results show that the object detection method can be used under conditions with light intensity more than 25 lux. It works optimally at speeds of 0.27 m/s to 0.42 m/s. In the horizontal motion control test, the overshoot parameter value is ±60%, rise time is 2s, settling time is 16s, and steady state error is ±20%. The AUV can track on a straight and winding path of 2 meters with a bright light intensity of ±493 lux, a dim light of ±107 lux and a dark light intensity of ±25 lux with the help of an LED beam with a light intensity of ±773 lux. The percentage of success of scoping experiments on a straight track and a winding track with three trials is 75%. This performance shows that the developed AUV works well to follow underwater cable.

SHALLOW WATERS DEPTH ESTIMATION USING EMPIRICAL SATELLITE DERIVED BATHYMETRY AND SENTINEL-2 DATA, CASE STUDY: EAST COASTAL WATERS OF JAVA ISLAND

Abstract. Hydrographic survey is an activity to provide spatial information in the marine sector. To produce accurate data, hydrographic surveys require very large costs. With the vast sea area in Indonesia, this becomes a very big challenge. In addition, there are some areas that cannot be reached by survey vessels (limited to a depth of > 25 m). Therefore, an alternative method is needed to provide bathymetry data in Indonesia. There is a new technique that is being developed and does not require high costs to obtain water depth data, by using remote sensing technology, especially by using passive sensor image technology. This technique or method is known as Satellite Derived Bathymetry (SDB) which can estimate depths of up to 30 meters. The SDB technique which is often used is empirical SDB. The empirical SDB has the principle of connecting the spectral value of the image with the measured depth. With the use of Sentinel-2 satellite imagery which has high temporal and spatial resolution, the SDB capability is expected to be improved. East coastal waters of Java Island are in the Bali Strait. This strait separates the island of Java from the island of Bali. In the Bali Strait there is a busy ferry shipping lane and there are also underwater cables used to supply electricity to Bali Island from Java Island. On the Java side, there are also many beaches and underwater tourism that must be preserved. Therefore, it is very important to be able to know the hydrographic data such as bathymetry data in the east coastal waters of Java Island. The objective of this work is thus to estimate shallow water depths using empirical SDB and Sentinel-2 images in the east coastal waters of Java Island. With two band combinations applied in the algorithm, best combination to produce the best depth map for the study area can be obtained. Comparing with reference data, the results show Band 1&3 combination give the better correlation and RMSE (0.76 and 0.026) than Band 2&3 combination (0.64 and 0.075).

Interconnections between International and National Criminal Law Relevant to Energy Security

Interconnections between International and National Criminal Law Relevant to Energy Security

Fault diagnosis of the constant current remote power supply system in CUINs based on the improved water cycle algorithm

Cabled Underwater Information Networks (CUINs) is an important platform for ocean observation where the Constant Current Remote Power Supply System (CCRPSS) guarantees the safe and normal operation of CUINs. The CCRPSS is mainly composed of the main node and underwater cables which require frequent fault diagnosis but how to improve the fault diagnosis rate is a difficult problem. This paper proposed a fault diagnosis method for the CCRPSS based on the Improved Water Cycle Algorithm (IWCA) and the multi-classifier group based on the Least Squares Support Vector Machine (LSSVM). Firstly, the multi-feature extraction method is used to obtain the characteristic information in the time and frequency domain; secondly, IWCA is established by combining the traditional Water Cycle Algorithm (WCA) with the chaotic mutation strategy, the elite memory strategy and the population reconstruction strategy. By applying 13 typical test functions to performance test, it can be found that the IWCA can effectively improve the global search ability and balance of the WCA algorithm. At last, IWCA is used to optimize the parameters of the LSSVM classifier and improve the classification efficiency. The comparisons of simulated results with traditional methods show that the proposed diagnostic model can not only obtain complete fault feature information, but also obtain the optimal classification parameters of LSSVM faster. Therefore, the proposed diagnostic method is verified to be suitable for the fault diagnosis of the constant current remote power supply system in CUINs.

Application of image processing technology in cable detection of underwater robot

Manual inspection of underwater cables has many problems, such as heavy labor intensity, high operation difficulty and low work efficiency. It is more effective to use underwater camera to capture images of underwater cables than manual inspection. The addition of subsea detection and construction equipment raises bottom sediment in the water and causes the water to become turbid and cloudy, it also reduces the contrast of the underwater image and adds irrelevant background information. Therefore, a method of cable location in turbid waters based on image processing is proposed. The method firstly applies the dark channel prior dehazing algorithm. An adaptive histogram equalization algorithm is used to improve the light distribution of underwater image after defogging. Then, we use the local adaptive dynamic threshold segmentation method to achieve the rough segmentation, and the fine segmentation of cable image is carried out by selecting each connected domain region. Finally, the cable pixel coordinates are obtained by the method of center line extraction and frequency domain transformation. Experimental result shows that the proposed algorithm has good effects in terms of clarity.

Maritime Asymmetric Warfare in Archipelagic States; The Indonesian Phenomena

Defending sovereignty within an island nation is relatively more complex than doing so for a continental state. The number of scattered islands makes straits and seas more penetrable, vulnerable points and targets of asymmetric threats at sea. The aim of this research is to illustrate threats at sea and provide solutions in guarding and monitoring Indonesian coastal borders, which currently require more ships and radar technology as well as other sensing equipment due to longer beaches. The results reveal that firstly, potential asymmetrical threats at sea include former WWII mines, underwater fibre cables, and nuclear submarines belonging to foreign countries such as America, Russia and China. Secondly, problems related to welfare include theft of natural resources like coral reefs and fish, and drug smuggling activities, all which add to the burden and duties of various parties. Thirdly, asymmetrical Narcoterrorism is very prominent in Colombia where drugs from Cannabis plants are sold to buy weapons. This is also happening in the Philippines and in Aceh, Indonesia. Narcotic activities are also increasingly worrying – particularly their effects on younger generations. Lastly, coordination by affiliated parties that help guard the sea is highly expected. Adequate maritime border patrol management must be carried out so that together, different marine security institutions can maintain the sovereignty of the state. Therefore, the following are recommended: a) regional diplomatic cooperation within ASEAN, b) ensuring of military capability, power, and readiness for placement, and c) the utilization of unmanned technology to aid in securing the archipelagic state.

Analytical and numerical study on underwater towing cable dynamics under different flow velocities based on experimental corrections

A relatively simple and fast mathematical analysis method is proposed to determine the position and posture of underwater towing cable under steady-state. The lumped mass method is used to discretize the towing cable into a series of finite segment elements connected by nodes. Based on the static analysis of Morrison equation and finite segment of the towing cable, the analytical formulas of the steady-state control equation of the underwater towing cable are obtained and solved. The numerical simulations and experiments are carried out for verification. As the drag coefficients have a great influence on the accuracy of the results of the mathematical analysis and numerical simulation, the influences of normal drag coefficient and tangential drag coefficient on the calculation result are discussed. The normal drag coefficient is corrected through the experiment to further improve the accuracy of mathematical analysis and numerical simulation, which is significant for the depth control of underwater towing system.

Cost-effective reliable transmission service for Internet of Flying Things

High-speed quality Internet provision for aircraft passengers is thought to be one of the major unresolved challenges for ubiquitous Internet provision. This article aims to resolve the problem of airborne Internet access with high quality of service for modern Internet of things devices. Large remote regions in the ocean along the busy air routes (e.g. Atlantic Ocean) require high-speed, reliable, and low-cost airborne Internet (i.e. Internet provision to the aircraft) to manage various delay- and throughput-sensitive applications. Conventional satellite-based solutions can be an alternate for Internet provision in such far-flung areas; but, such solutions are lacking quality of service (with longer delays and low bandwidth) and are significantly costly. Fortunately, the underwater optical fiber cables deployed across the oceans pass along the same busy air routes. This infrastructure of underwater optical fiber cables can be exploited for Internet backbone providing high quality of service for wireless Internet provision to the commercial aircraft. Dedicated stationary ships deployed along these underwater optical fiber cables can be utilized for Internet provision, navigation, and security to ships and aircraft. This article not only proposes the networking infrastructure of the submarine cable-based airborne Internet access architecture but also presents a novel routing scheme for airborne ad hoc networks. Also, we analyze quality of service provision as compared to other existing techniques. Our simulation results show that our proposed solution outperforms other existing schemes for airborne Internet service provision, in the presence of high mobility and dynamic topology changes.

Integration of marine spatial objects management to support toward sustainable maritime policy development

Utilization of land and marine potential is an absolute right mandated in Article 33 of the 1945 Constitution. One of the efforts to manage land and marine potential includes the integration of the management of land and marine space objects in the context of sustainable maritime development. However, the implementation of management of marine space objects is overlapping in legal, technical, and institution aspects. Based on ownership of rights and their use, marine space objects are not only limited to the fishery and tourism, but also marine structures, cultivation, underwater treasures, underwater cables and pipes, conservation, customary culture, garbage disposal, shipping, energy and mineral resources, renewable resources, and military. This study will determine maritime policy that can provide assurance of legal, technical, and institutional aspects of management especially for marine space objects. It regulates rights, boundaries, management and an integrated maritime information system. The policy includes management of ownership, use and economic value of marine space. Marine space ownership data consists of the subject and marine space objects. Data on the use of marine space consists of characteristics of marine space, marine spatial use planning and monitoring and evaluation of the implementation of marine space utilization. Meanwhile, data on the economic value of marine space includes information related to the marine space assessment system as well as taxation related to marine space.

Real-time estimation of riser's deformed shape using inclinometers and Extended Kalman Filter

The real-time monitoring of underwater risers, cables, and mooring lines by multiple sensors is in great demand but still very challenging. In this study, a new real-time riser monitoring method based on an Extended Kalman Filter (EKF) is proposed. It estimates the overall shape of riser in real-time utilizing the measured signals from multiple bi-axial (inclination and heading) inclinometers along the riser. The novel EKF algorithm is shown to be robust against sensor noises and successfully reproduces the actual riser profiles at each time step, which has been verified by multiple tests through numerical simulations. For verification, a turret-moored FPSO (Floating Production Storage and Offloading) with a SCR (Steel Catenary Riser) is employed in four different random waves and currents. Subsequent algorithms are also developed so that the corresponding bending and axial stresses along the riser can also be estimated in real time from the obtained riser shape, which can further be used for the real-time estimation of fatigue-damage accumulation.

Infrastructure Study for Solving Connectivity Problems Through the Nile River

Fiber optics cables present various benefits over regular cables when used as a data transportation medium in today’s communication networks. It is noted that there are significant challenges in the connectivity of inner cities that are located far inland away from the coastal areas. Most of the networks developed in Africa, especially in Egypt, are connected via submarine cables flowing across coastal areas. Very few connections are constructed to connect inner cities by crossing the Nile. The Nile River is characterized by a wide area, offering a natural path for underwater cables’ laying areas. In this study, the analysis and evaluation of the laying of these cables along the bed of the Nile River in Egypt, rather than crossing it, is investigated. There are many issues with laying fiber optic cables across the Nile River. Some of these are the requirement of using more than one node over fiber optic cable for each. When the number of nodes increases, the cost of installation and drilling effort increases with each node. The fiber optic cable path along the Nile River is simulated with a numerical model (Delft-3D). Two different scenarios for laying cables were applied and analyzed to evaluate the effect of the predicted water surface and sediment profiles on the fiber optic cable path. Based on the results obtained, the fiber-optic network infrastructure is proposed to solve connectivity problems by laying fiber optic cables along the Nile River.

Toward a Highly Accurate Classification of Underwater Cable Images via Deep Convolutional Neural Network

Underwater cables or pipelines are commonly utilized elements in ocean research, marine engineering, power transmission, and communication-based activities. Their performance necessitates regularly conducted inspection for maintenance purposes. A vision system is commonly used by autonomous underwater vehicles (AUVs) to track and search for underwater cable. Its traditional methods are characteristically applicable in AUVs, wherein they are equipped with handcrafted features and shallow trainable architectures. However, such methods are subpar or even incapable of tracking underwater cable in fast-changing and complex underwater conditions. In contrast to this, the deep learning method is linked with the capacity to learn semantic, high-level, and deeper features, thus rendering it recommended for performing underwater cable tracking. In this study, several deep Convolutional Neural Network (CNN) models were proposed to classify underwater cable images obtained from a set of underwater images, whereby transfer learning and data augmentation were applied to enhance the classification accuracy. Following a comparison and discussion regarding the performance of these models, MobileNetV2 outperformed among other models and yielded lower computational time and the highest accuracy for classifying underwater cable images at 93.5%. Hence, the main contribution of this study is geared toward developing a deep learning method for underwater cable image classification.

Study for Operation Method of Underwater Cable and Pipeline Burying ROV Trencher using Barge and Its Application in Real Construction

Study for Operation Method of Underwater Cable and Pipeline Burying ROV Trencher using Barge and Its Application in Real Construction

Dynamics Modeling and Motion Simulation of USV/UUV with Linked Underwater Cable

This paper describes a study on the dynamic modeling and the motion simulation of an unmanned ocean platform to overcome the limitations of existing unmanned ocean platforms for ocean exploration. The proposed unmanned ocean vehicle combines an unmanned surface vehicle and unmanned underwater vehicle with an underwater cable. This platform is connected by underwater cable, and the forces generated in each platform can influence each other’s dynamic motion. Therefore, before developing and operating an unmanned ocean platform, it is necessary to derive a dynamic equation and analyze dynamic behavior using it. In this paper, Newton’s second law and lumped-mass method are used to derive the equations of motion of unmanned surface vehicle, unmanned underwater vehicle, and underwater cable. As the underwater cable among the components of the unmanned ocean platform is expected to affect the motion of unmanned surface vehicle and unmanned underwater vehicle, the similarity of modeling is described by comparing with the cable modeling results and the experimental data. Finally, we constructed a dynamic simulator using Matlab and Simulink, and analyzed the dynamic behavior of the unmanned ocean platform through open-loop simulation.

Sensors to Increase the Security of Underwater Communication Cables: A Review of Underwater Monitoring Sensors.

Underwater communication cables transport large amounts of sensitive information between countries. This fact converts these cables into a critical infrastructure that must be protected. Monitoring the underwater cable environment is rare and any intervention is usually driven by cable faults. In the last few years, several reports raised issues about possible future malicious attacks on such cables. The main objective of this operational research and analysis (ORA) paper is to present an overview of different commercial and already available marine sensor technologies (acoustic, optic, magnetic and oceanographic) that could be used for autonomous monitoring of the underwater cable environment. These sensors could be mounted on different autonomous platforms, such as unmanned surface vehicles (USVs) or autonomous underwater vehicles (AUVs). This paper analyses a multi-threat sabotage scenario where surveying a transatlantic cable of 13,000 km, (reaching water depths up to 4000 m) is necessary. The potential underwater threats identified for such a scenario are: divers, anchors, fishing trawls, submarines, remotely operated vehicles (ROVs) and AUVs. The paper discusses the capabilities of the identified sensors to detect such identified threats for the scenario under study. It also presents ideas on the construction of periodic and permanent surveillance networks. Research study and results are focused on providing useful information to decision-makers in charge of designing surveillance capabilities to secure underwater communication cables.