Ocean Engineering Commons^™

Intelligent Formation Control Using Orfbls And Adaptive Backstepping Sliding-Mode Control To Address Uncertain Tilting In Multi-Quadrotors During Wind Gusts, Ching-Chih Tsai, Chun-Fu Mao, Kumail Hussain

Journal of Marine Science and Technology–Taiwan

In terms of aerial robotics, stable and precise formation control is a significant challenge for tilting multi-quadrotors during disturbances. This paper proposes a fixed-time formation control strategy for tilting multi-quadrotors to address the effect of external wind gusts. The observer accurately predicts environmental disturbances and an adaptive backstepping sliding-mode control (ABSMC) method with an output recurrent fuzzy broad learning system (ORFBLS) addresses these disturbances within a finite time. ORFBLS dynamically adjusts its structure through a growing ORFBLS structure to allow nodes to be added as needed. The method's stability is validated using Lyapunov stability theory and ensures the convergence of …

Visually Guided Landing System On Ship Deck For Multicopter, Dong-Lin Li, Shih-Kai Lee, Tzu-Hsiang Chou

Journal of Marine Science and Technology–Taiwan

Traditionally, high-value fish have been located at sea using helicopters. However, with advancements in technology, maritime drones have become increasingly important in recent years. Compared to traditional helicopter-based methods, drones offer significantly lower operational costs, making them cost-effective. However, the challenging sea conditions, including strong winds and the swaying motion of vessels, pose significant challenges for drone landings.

This paper proposes a stable approach for multicopter landing on ships at sea, incorporating improved marker detection, enhanced wind resistance control, and more accurate deck motion prediction. In the marker detection phase, we introduce a method to improve the accuracy of ArUco …

Typology And Spatiotemporal Patterns Of Illegal Fishing Activities In The Philippines: Implications For Fisheries Management, Marlowe O. Acevedo, Tzu-Yun Ching, Chih-Shin Chen

Journal of Marine Science and Technology–Taiwan

Illegal, unreported, and unregulated (IUU) fishing activity is a global threat and continues to undermine the effectiveness of fisheries regulations and management measures. However, the extent of illegal fishing in Philippine waters remains unclear. This study aims to identify the types of illegal fishing in Philippine waters and analyzed their temporal and spatial patterns. Data were obtained from the records of the Philippine Coast Guards (PCG) and Maritime Law Enforcement Agencies from 2015 to 2020. A total of 602 apprehensions were recorded, resulting in 813 violations, of which 630 cases were fishery violations. Most of the watercrafts involved in the …

The Effect Of Chamber Geometry On The Performance Of Oscillating Water Column, Timilehin O. Osunade

College of Graduate Studies: Theses & Dissertations

This thesis investigates the effect of internal chamber geometry on the performance of a piezoelectric oscillating water column (OWC) wave energy harvester. Four acrylic chamber configurations with internal top-surface angles of 0°, 30°, 45°, and 60° were tested under 32 controlled conditions combining synchronous (SYN) and asynchronous (ASC) forcing at input voltages of 4, 6, 8, and 10 V. A 35 mm piezoelectric disc mounted at the chamber roof served as the power take-off element and, subject to the RC-limit caveat disclosed in Section 3.2.1, as a first-order dynamic analogue of the chamber pressure for phase-based compressibility analysis. All test …

Experimental Rate Feedback Control Of A Model-Scale Hourglass-Shaped Heaving Point Absorber, James R. Halverson

Dissertations, Master's Theses and Master's Reports

Buoy geometry greatly affects a point absorber wave energy converter's dynamic response to waves. Finding the optimal buoy shape and control method remains an open research area focused on maximizing the conversion of wave kinetic energy into electricity. This work presents an experimental comparison of closed-loop energy extraction between a cylindrical and a truncated cone buoy, both with the same submerged volume, across various wave frequencies and amplitudes. To ensure a fair comparison, the optimal rate feedback gain is calculated for each buoy at each wave condition. Multiple metrics, including power output, capture width, and actuator force, are used to …

Analytical And Data-Driven Modeling And Control Of Nonlinear Point Absorber Wave Energy Converters With Application To Cone–Cone Buoy Geometries, Houssein Yassin

Dissertations, Master's Theses and Master's Reports

This dissertation develops analytical modeling, numerical simulation, experimental validation, and data driven control methods for nonlinear point absorber wave energy converters, with particular emphasis on cone--cone buoy geometries. Geometry dependent nonlinear force models are first derived using pressure field and displaced volume formulations. These models show how buoy geometry produces nonlinear Froude--Krylov and restoring forces, including the dominant cubic behavior of cone--cone geometries.

The derived models are incorporated into a feedback linearization framework that compensates selected nonlinear dynamics while retaining the incident wave terms. An analytical optimal control formulation is also developed to maximize harvested energy in nonlinear, nonautonomous systems …

Application Of Reactive Power Theory To Wave Energy Converters Under Multi-Frequency Excitation: Analysis And Experimentation, Mckenna R. Collins

Dissertations, Master's Theses and Master's Reports

There is abundant energy surging in the oceans across the globe. However, there have been technological challenges in extracting that energy for use. Wave energy converter (WEC) technology is being developed to find innovative ways to convert wave kinetic energy into electricity, but there are still efficiency obstacles that inhibit large-scale use. Focusing on heave-point absorber control theory, this thesis continues the work to improve the efficiency of WECs. This is done by leveraging a superposition of linear mass-spring-damper models to analyze a WEC under multi-frequency excitation and applying proportional-derivative gains to each linear model. However, to analyze this system, …

A Quantitative Analysis Of Burrowing And Subterranean Locomotion In The Sand Lance Using A Transparent Sediment, Issei Fujita, Makoto Tomiyasu, Jun Yamamoto, Yasuzumi Fujimori

Journal of Marine Science and Technology–Taiwan

Sand lances (Ammodytes spp.) rely on rapid burrowing into sediment for predator avoidance. Although their sediment grain-size preferences are well documented, the biomechanics underlying burrowing success remain unclear because natural substrates are opaque. Using a transparent-sediment system, we directly visualized and quantified burrowing kinematics to: (1) test the effect of body size (total length, TL) on burrowing success; (2) examine entry mechanisms (e.g., swimming speed, entry angle); and (3) describe locomotion within sediment. Logistic regression on the full dataset (N = 28 fish) identified TL as the primary determinant of success, with larger individuals exhibiting significantly higher success …

Cruise Network Design Under Sequential Duopolistic Entry, Ta-Hui Yang, Ching-Hui Tang, Wan-Tien O

Journal of Marine Science and Technology–Taiwan

This study addresses the network design for international cruise services in a duopolistic market, where carriers enter and make decisions sequentially. The leader, who makes the first move, makes decisions as there is no competitor in the market. The follower, who makes decisions later, has to design their network considering the existing leader’s network. The leader’s model is a mixed integer linear problem while the follower’s model is a mixed integer nonlinear problem. Therefore, a heuristic is proposed to solve the problem. The commercially available general algebraic modeling system is used in conjunction with its different solvers to solve the …

Effect Of Heat Treatment On The Corrosion And Wear Behavior Of 17-4 Ph Stainless Steel For Marine Applications, Syuan Tai, I-Kon Lee, Ming-Yuan Lin, Kang-Yu Liao, Chin-Chun Chang, Hung-Bin Lee

Journal of Marine Science and Technology–Taiwan

This study explores the tribocorrosion behavior of conventionally cast 17-4 PH stainless steel under real seawater conditions, focusing on the effects of three heat treatments (Solution, H900, H1100). Electrochemical tests, tribocorrosion experiments, SEM, XPS, and quantitative analysis were used to establish a three-stage tribocorrosion mechanism. Results show that H900 exhibits superior corrosion and wear resistance, while H1100 suffers increased material loss and surface cracking at high potentials. Elemental analysis revealed NbC migration forming third-body particles, which, although briefly reducing friction, induced local stress concentration and crack initiation. The findings highlight the critical influence of microstructure, passive film stability, and third-body …

Enhancing Underwater Imagery And Organism Detection Using Reinforcement Learning, K. Arul Deepa, P. Ramya, Karpaga Vinodha, Dharmaraja C

Journal of Marine Science and Technology–Taiwan

Underwater environments pose significant challenges in assessing image quality and organism detection due to light scattering and absorption, which limits visibility and color fidelity. Existing solutions often fail to effectively address these challenges, resulting in suboptimal image quality and hindering organism identification. This paper examines the problem through a dual-focused approach: enhancing underwater images and detecting organisms using the Underwater Image Enhancement Benchmark (UIEB) dataset. The first step introduces a state-of-the-art method for image enhancement by applying reinforcement learning (RL) principles. By formulating the enhancement process as a Markov Decision Process (MDP)—where states are represented by image features and actions …

Hydrodynamics Of Perforated Heave Plates, Muhammad Usman

All Dissertations

Ocean waves are a clean and renewable energy source that can help reduce dependence on fossil fuels and combat climate change. To capture this energy, researchers have developed devices known as wave energy converters (WECs). One common type, called a two-body point absorber WEC, uses a buoy floating on the ocean surface connected to a submerged reaction plate, known as the heave plate, which lies underwater. The relative up-and-down motion between the buoy and the heave plate, driven by ocean waves, generates usable power via a power take-off (PTO) system. Traditionally, these submerged heave plates are solid structures. However, this …

Development Of New Design Criteria For Coastal Highway Embankment Under Wave-Induced Loading, Udaya Bilas Panta

Master's Theses

In the face of intensifying hurricanes and rising sea levels, Louisiana’s coastal highways, lifelines for communities and commerce, stand increasingly vulnerable. This thesis introduces a pioneering methodology for designing geosynthetic-reinforced highway embankments capable of withstanding wave-induced loading and rapid drawdown scenarios, the most critical failure condition identified in coastal environments. By integrating statistical wave modeling, advanced numerical simulations using SEEP/W and SLOPE/W, and a comprehensive parametric analysis, the study develops a novel hybrid regression formula that accurately predicts optimal reinforcement lengths based on site-specific geotechnical and hydraulic parameters. Validated against Hurricane Katrina data and real-world soil profiles from Cameron Parish, …

User Interface And Watchstation Improvements Required For Multi-Vehicle Usv Operations, Val Schmidt, Joshua Bergeron

Faculty Publications

In October 2024, the University of New Hampshire and NOAA’s Uncrewed Systems Office embarked on a mapping mission in the Gulf of Maine, simultaneously operating two DriX Un-crewed Surface Vehicles. Goals of the project were focused on testing hypotheses related to concepts of operation, including the safety of operations, cognitive loading of operators, management of vehicle endurance, vehicle logistics, maintenance and field support, refueling and a host of others.

Development Of Green Port Index : A Tool For Assessing Ports Based On Implementation Of Ghg Emission Reduction Measures, Mamadou Lamin Bajo

World Maritime University Dissertations

No abstract provided.

Feasibility Of Adopting Reformed Methanol–High Temperature Proton Exchange Membrane Fuel Cell Technology For The Propulsion Of Seagoingvessel, Toochukwu Patricia Obasi

World Maritime University Dissertations

No abstract provided.

Exploring Challenges And Opportunities For Green Shipbuilding In South Africa : A Maritime Energy Management Perspective, Masego Mmamolobye Lucia Mosupye

World Maritime University Dissertations

No abstract provided.

An Analysis Of Renewable Energy Capture Utilization For Mpulungu Harbour, Dorica Nayame

World Maritime University Dissertations

No abstract provided.

Examining The Perception Of Maritime Instructors In Upskilling And Reskilling Seafarers Towards Decarbonization, Michelle Margallo

World Maritime University Dissertations

No abstract provided.

Enhancing Seafarer Competence In Nigeria : Challenges And Opportunities, Alexander Chike Melifonwu

World Maritime University Dissertations

No abstract provided.