Engineering Commons^™

Dances And Escape Of The Vortex Quartet, Brandon Behring

Dissertations

This dissertation considers the linear stability of a one-parameter family of periodic solutions of the four-vortex problem known as 'leapfrogging' orbits. These solutions, which consist of two pairs of identical yet oppositely-signed vortices, were known to W. Gröbli (1877) and A. E. H. Love (1883) and can be parameterized by a dimensionless parameter related to the geometry of the initial configuration. Simulations by Acheson and numerical Floquet analysis by Tophøj and Aref both indicate, to many digits, that the bifurcation occurs at a value related to the inverse square of the golen ratio. Acheson observed that, after an initial period …

Experimental And Numerical Investigations On The Hydrodynamic Characteristics Of The Planar Motion Of An Open-Frame Remotely Operated Vehicle, Ying-Fei Zan, Rui-Nan Guo, Li-Hao Yuan, Shi-Peng Wang, Da-Zhong Zhang, Shi-Jing Xu, Zhao-Hui Wu

Journal of Marine Science and Technology

In this study, the longitudinal, sideways, vertical, and sideslip motions of an open-frame remotely operated vehicle (ROV) were experimentally and numerically investigated. The open-frame ROV was designed to be asymmetric in both the longitudinal and vertical directions to achieve special functionalities. A physical ROV model was tested in a towing tank with different velocities and sideslip angles in the horizontal and vertical planes. A numerical simulation was conducted with the same working conditions used in the scaled model tests by using a segregated flow solver based on Reynolds-averaged Navier–Stokes equations. This study investigated the effect of the hydrodynamic forces (moments) …

Vision Based Target Recognition For Cage Aquaculture Detection, Chao-Xun Chen, Jih-Gau Juang

Journal of Marine Science and Technology

This study applies Unmanned Aerial Vehicle (UAV) to netcage fish-farming. The UAV can fly thru cages along a predefined route. At each cage, the UAV can automatically drop sensors to collect the environment data around the cage. However, low cost commercial or assembled drone might not have precise Global Navigation Satellite System (GNSS). Also, there are many uncertain factors cause Global Positional System (GPS) instability, like weather, location…etc. The main idea of this study is using GPS to guide the drone to approximated location of each cage. Then, apply image recognition to obtain the net-cage and UAV relative position. After …

Study On Multi-Dof Search And Salvage Robot In Shallow Water, Jun-Bing Qian, Nan Pan, Xiao-Jue Guo, Yi Liu

Journal of Marine Science and Technology

For underwater robots working in a variety of risky, unpredictable, and complex underwater environments – with factors such as turbulence, vortex, wind, wave, and deep-water pressure – it is necessary to ensure good structural design and handling performance in the process of robot design. Based on the requirements of achieving the stability design, control system, and underwater vision system of the robot, this paper proposes the structural design of a police multipurpose underwater robot power system that realizes both stable and flexible movement. A 6-DOF driving method was designed and its motion analysis was performed. In the vision system, an …

Research On Structural Design And Vision System Of Narrow Shallow Water Multipurpose Underwater Robot, Nan Pan, Xiao-Jue Guo, Jun-Bing Qian, Yong-You Luo, Yi Liu

Journal of Marine Science and Technology

In the narrow shallow water area, the underwater environment is complex and changeable, and the water area is narrow. Because of water body flow, various risks and unpredictable conditions, such as turbulence, vortex, disturbance, and so on exist which could seriously interfere with the motion and control of the underwater vehicle. In this way, the automatic stability and flexibility of multi-dimensional motion under external disturbance becomes the basis and requirement of underwater control and operation. In this paper, the structure design of the main body and power system of the narrow shallow water multi-purpose underwater vehicle was proposed to realize …

An Enhanced Sliding Mode Control Method For Wave Compensation System Of Ship-Mounted Cranes With Roll Motions And Parametric Uncertainties, Hai-Yan Qiang, Si Xie, Zhi-Qiang Xu, You-Gang Sun

Journal of Marine Science and Technology

Ship-mounted cranes are widely used in offshore constructions, resource exploitation and marine salvages, to transfer payloads. Due to serious sea conditions, unexpected motions of the ships caused by the wave will probably pose serious efficiency and security issues. Thus, the wave compensation system has become necessary equipment for the shipmounted crane. But wave-induced motions of the ship, parametric uncertainties and nonlinearities remain challenges for control of wave compensation systems, which needs to be solved urgently. In this paper, the mathematical model of the wave compensation system is established firstly. Then, a sliding mode controller is presented and the stability is …

Short-Term Fatigue Damage Of Tethers Of Long-Span Floating Cable Supported Bridges Under Harsh Waves, Deokhee Won, Keesei Lee, Young-Jong Kang, Seungjun Kim

Journal of Marine Science and Technology

A floating bridge can be effectively used for sea-crossing in deep water. Because the superstructure of the bridge is supported by floating substructures with pontoons, the conventional fixed piers, towers, foundations, and piles are not required. Instead, a rational mooring system can be used to strictly maintain the target position of the floating substructures against environmental loads, including winds, waves, and currents. Recently, long-span cable-supported bridges with floating towers were investigated and found to overcome the limitations of conventional cable-supported bridges, when used as sea-crossing infrastructure. To design the moorings for very large floating structures, the structural safety should be …

Collision Warning System For Small Maritime Autonomous Surface Ships, Won-Sik Kang, Young-Soo Park, Jeong-Bin Yim

Journal of Marine Science and Technology

In this study, wireless communication technologies used in road and marine traffic are compared and analyzed to develop a collision warning system for small maritime autonomous surface ships based on sufficient testing and technologically advanced wireless access in vehicular environment (WAVE) communication technology. Outstanding communication technologies, such as WAVE, have been used as the core technology for the infrastructural development of an intelligent transport system (ITS) as well as autonomous vehicles in many countries and industries. In WAVE communication, information is transmitted in 100-ms intervals. Therefore, it is feasible to maintain control of ships by fully supplementing the update interval …

Identifying High-Collision Potential Vessel-Bridge Pairs In Vessel Traffic Service, Jeong-Bin Yim, Chun-Ki Lee

Journal of Marine Science and Technology

Collision risk assessment for maritime traffic monitoring in vessel traffic service (VTS) is a key technology for ensuring the safety of both vessels and bridges. This study proposes a risk assessment methodology using a single measure of collision risk ratio that could assist in reducing the cognitive load of VTS operators. To explain the proposed method, we first define the semantic and mathematical relationship of vessel– bridge pier collisions; then, we establish the risk assessment framework using the collision risk ratio by combining deviation angle and stopping distance probabilities. To validate the proposed method, we conducted an experiment in the …

Modeling Navigator Errors In Collisions Using Hidden Markov Models, Deuk-Jin Park, Jeong-Bin Yim, Chun-Ki Lee

Journal of Marine Science and Technology

Understanding navigator errors can be used as a basis for preventing collisions. Here, Hidden Markov Models (HMMs) are applied to navigator errors of fishing and merchant ships in collisions. Information on navigator errors providedin accident investigation reports issued by the Korean Maritime Safety Tribunal is surveyed. The surveyed information is converted into data using the framework of slips, lapses, and mistakes proposed in this study. The results of framework data states are inferred using the unsupervised learning of HMMs, with sequences of navigator errors contained in the error data. The expected errors learned using the navigator error models for fishing …

Study On Underwater Navigation For Underwater Track Vehicle, Dae-Hyeong Ji, Hyeung-Sik Choi, Sang-Ki Jeong, Hyun-Joon Cho, Ji-Hyeong Lee, Wen-Hsiang Hsieh

Journal of Marine Science and Technology

In this study, an underwater navigation algorithm was developed to apply a navigation system to an underwater track vehicle (UTV). Generally, a Doppler velocity log (DVL) is used to obtain the velocity information of underwater vehicles. However, a DVL cannot be used in a UTV owing to vehicle vibration and limited sensing distance. Hence, dead reckoning navigation is typically used, which results in severe errors in altitude and position values over long periods of operation. To address these problems, in this study, we developed a new underwater navigation system for a UTV using navigation sensors comprising an inertial navigation system, …

A New Complex Marine Unmanned Platform And Field Test, Jihyeong Lee, Han-Sol Jin, Hyunjoon Cho, Jiafeng Huang, Sang-Ki Jeong, Dae-Hyeong Ji, Hyeung-Sik Choi

Journal of Marine Science and Technology

This paper presents the development of a new complex marine unmanned platform composed of an unmanned surface vehicle (USV) and a remotely operated vehicle (ROV), and the results of a sea test. The platform structure, control system, sensor system, and control algorithm were developed and are introduced. The complex platform collects information of the underwater structures, such as the wall, floor, and piers and harbors. Using a tether cable, the ROV is connected to the USV for power supply and to receive a large amount of underwater data obtained using a sonar scanner or a camera in real time. The …

A Study On Hydrodynamic Forces Induced By Liquid Tank Of Lng Carrier In Waves Based On Experiment And Recurrent Neural Network, Van Minh Nguyen, Thi Thanh Diep Nguyen, Hyeon Kyu Yoon

Journal of Marine Science and Technology

The sloshing of liquid in a partially filled tank is of great concern to aerospace vehicles, road vehicles and ships due to complex nonlinear motion involving the free surface of the liquid. Sloshing is a type of violent liquid motion that is created by forces such as an impact and breaking waves. Oscillation of the liquid in the vessel may threaten navigation safety. This paper attempts to predict the hydrodynamic forces induced by the motion of liquid inside a tank based on experiment and Recurrent Neural Network (RNN). The experiment of sloshing test is carried out using the Stewart platform …

Internal Force Evaluation Of A Submerged Floating Pipeline Under Irregular Waves, Deokhee Won, Jihye Seo, Jong Sup Park, Seungjun Kim

Journal of Marine Science and Technology

Generally, submarine pipelines are laid on the seabed to transport water, oil, natural gas, and electricity to the land using submarine cables. However, they are not suitable for all seafloor conditions. There are environmental concerns such as deep seas, irregular seabed features, soft soils, transported materials and so on. To overcome these challenges, a submerged floating pipeline (SFP) concept was proposed. To stay in the middle of the water, the SFP has buoyant modules as floating devices. It is unrestricted under environments such as uneven seabeds, and deep waters, and is suspended to avoid interrupting passing vessels. This SFP model …

Dynamic Behavior Of A Long-Span Cable-Stayed Bridge With Floating Towers After The Sudden Failure Of Tethers And Cables Under Irregular Waves, Minseo Jang, Yunwoo Lee, Seungjun Kim, Young-Jong Kang

Journal of Marine Science and Technology

Cable-supported bridges with floating towers do not require fixed piers at the seabed. Therefore, innovative conceptual models have been continuously developed to overcome the limitations of conventional bridges in deep waters. The main floating tower that supports superstructures using stay cables is balanced by the buoyancy of floaters moored by tethers. The applicability of floating bridges should be verified by evaluating the overall stability considering the tether design. Here, various cases of the sudden failure of tethers and stay cables under the environmental conditions of a 100-year return period are simulated in a time-domain. The floating cable-stayed bridges are subjected …

Remote Sensing Analysis Of Cold Water Temporal And Spatial Variability In The East Sea, Suk Yoon, Hyun Yang

Journal of Marine Science and Technology

In this study, we monitored temporal and spatial variability in summer cold water events in the East Sea of Korea. We defined cold water as seawater that is ≥ 5°C colder than the surrounding area. When cold water expands or changes in propagation direction, the National Institute of Fisheries Science (NIFS) of Korea issues a cold water upwelling warning to prevent aquafarm damage. To understand cold water effects, we analyzed the causes of continuous and strong cold water events, and propagation thereof, using satellite and in situ data for summer to autumn in the period 2011–2019. To investigate the cold …

A Study On An Accurate Underwater Location Of Hybrid Underwater Gliders Using Machine Learning, Sang-Ki Jeong, Hyeung-Sik Choi, Dea-Hyung Ji, Mai The Vu, Joon-Young Kim, Sung Min Hong, Hyun Joon Cho

Journal of Marine Science and Technology

A hybrid underwater glider (HUG) is marine observation equipment that consumes a small amount of energy and offers greater range and navigation times. To achieve reduced energy consumption, however, the HUG uses imprecise navigation sensors, such as mems-type GPS and AHRS, resulting in inaccurate coordination. This study makes a new attempt on the application of machine learning algorithms in a way that complements sensor data errors to improve navigation performance. The proposed algorithm was used to a simulation of the HUG’s navigation and control system, after which the updated heading angle was decided by using the previous position data and …

Dynamic Modelling And Experimental Results Of A Ray-Type Hybrid Underwater Glider With A Dualbuoyancy Engine, Ngoc-Duc Nguyen, Hyeung-Sik Choi, Sung-Wook Lee, Wen-Hsiang Hsieh, Sang-Ki Jeong, Dae-Hyeong Ji

Journal of Marine Science and Technology

For ocean observation and exploration, underwater gliders (UG) have shown their efficient long-range operation with buoyancy propulsion. The current Torpedo-shape UGs have small buoyancy capacity and insufficient space for batteries and sensors. In this paper, a Ray-type hybrid underwater glider (RHUG) is developed with new hull design, dual-buoyancy engine, and thrusters. The control system of the RHUG is constructed for gliding motion. To understand the characteristic of the RHUG, dynamic modelling of the dual-buoyancy engine was established. To verify the proposed dynamics model, a navigation experiment using the developed RHUG platform was carried out. Through comparison between experiment and simulation …

A Study On The Analysis Of Minimum Speed Control Effect Using Queue Model Focused On Busan Port, Sangwon Park, Won-Sik Kang, Young-Soo Park

Journal of Marine Science and Technology

VTS aims to increase the efficiency of maritime traffic in two ways. The first is a decrease in marine accidents, and the second is an increase in the utilization rate of infrastructure such as waterways and port facilities. This means that, if safety is guaranteed, efficiency must also be considered in the VTS. The purpose of this study is to quantitatively analyze the effects of speed regulation under safe conditions for an efficient use of waterways. A model was developed using a queue approach, and the effect of the waiting time according to the minimum speed proposal was analyzed through …

Development Of Collision Avoidance Algorithm Based On Consciousness Of Ship Operator, Eunkyu Lee, Young-Soo Park, Minjeong Park, Myoung-Ki Lee, Eunbi Park, In-Young Gong

Journal of Marine Science and Technology

Several collision avoidance algorithms employing various methods have been developed to date. In this paper, a collision avoidance algorithm is proposed based on the potential assessment of risk (PARK) model, which is a maritime traffic risk assessment model based on the characteristics of the Korean coastal regions and the consciousness of a ship’s operator. The proposed collision avoidance algorithm is intended to be used in the transition period during which autonomous and human-operated ships sail simultaneously. The algorithm avoids collisions using the PARK model that reflects the International Regulations for Preventing Collisions at Sea. Situations such as head-on, crossing, overtaking, …

Design And Control Techniques Of The Open-Circuit Subsonic Wind Tunnel With Closed Testing Section, Jamshid Yakhshilikov, Jamshid Inoyatkhodjaev

Acta of Turin Polytechnic University in Tashkent

This paper will describe the design and control techniques of the open-circuit subsonic wind tunnel with closed testing section (WT) for study purpose. The goal is to design a WT that can be tested at a wind speed of 30 m/s, where the desired cross-sectional area of the test chamber is 0.5x0.5 m. The pressure drop inside the WT has been calculated in order to select one of the available axial fans from the manufacturer’s catalog, and computational fluid dynamics (CFD) was performed to check the result. In order to obtain a smooth airflow in the test section, a proportional …

Considerations For The Design Optimization Of Floating Offshore Wind Turbine Blades, Evan M. Gaertner

Doctoral Dissertations

Floating offshore wind turbines are an immature technology with relatively high costs and risk associated with deployment. Of the few floating wind turbine prototypes and demonstration projects deployed in real metocean conditions, all have used standard turbines design for onshore or offshore fixed bottom conditions. This neglects the unique unsteady aerodynamics brought on by floating support structure motion. While the floating platform has been designed and optimized for a given rotor, the global system is suboptimal due to the rotor operating in conditions outside of which it was design for. If the potential offered by floating wind turbines is to …

The Design And Validation Of A Uav Propeller Intended For Extremely Low Reynolds Number Environments, Benjamin Hebert

Electronic Theses and Dissertations

Mars exploration and UAV development have both advanced significantly over the past century, and are now being considered in tandem. Currently needed are UAV propellers that can operate in the Martian atmosphere. Flow will be in the range of Re < 20,000, creating extreme conditions not typically examined. A Blade Element Momentum Theory (BEMT) algorithm is developed using a variety of corrections designed specifically for low Reynolds number and rotational flows. Due to both the simplicity of the basic BEMT formulation, corrections are easy to put in place and often necessary to achieve accurate estimates. Aerodynamic coefficients are determined from XFOIL code, and have questionable accuracy in this regime. To account for this, a correction model is developed by comparing XFOIL results to experimental results of airfoils at low Re. This is all tested against a previous low Re propeller experiment. The results of this comparison are used to adjust the values in the correction, to produce more accurate results for theoretical design.

From here, a design philosophy for the propeller is developed using established methods and previous experimental data. High thrust is prioritized, with efficiency being a secondary concern. A hard mach limit of 0.7 is set to avoid major drag penalties, limiting the usable ranges of RPM and radius. Airfoil designs are then examined, based on previous designs, theoretical intuition, and …

The Earliest Drawings Of Dogs, Myles Bradley

Fall Student Research Symposium 2020

The oldest depictions of dogs ever found are over 8,000 years old, found carved into a cliff in the desert of Saudi Arabia. Studies show, however, that dogs are found coexisting with humans as far back as 30,000 years ago. If this is the case, "Why does it take so long for dogs to appear in human artwork?" Dogs have certainly been an integral part of human society for almost as long as they've been around, so what do these early images reveal about the ancient relationship between dogs and man? This paper explores possible answers to both of these …

Static Heat Exchanger For The Wireless Charging Of Electric Vehicles, James Mullen

Fall Student Research Symposium 2020

The USU College of Engineering partnered with the Aspire NSF Engineering Research Center to develop wireless charging pads for electric vehicles. These concrete pads, when placed in roadways, charge the batteries of electric vehicles that pass over them. As the pads charge vehicles, they produce excessive thermal energy (heat), which dissipates slowly through the surrounding concrete. This excess heat reduces the efficiency of the charging apparatus and can damage the imbedded electrical components. To manage the pad temperatures, the USU Nanoscale Thermal Energy Lab proposed to submerge the heat-generating elements in a Phase Change Material (PCM). As a solid, a …

The Dog As A Trend In Art, Whitney Stewart

Fall Student Research Symposium 2020

I have always believed that art is one of the biggest forms of communication and signs of cultural assimilation and it has been throughout history. I choose to explore the role that dogs play in this theme. From changes in the symbolism of the dog and the ethics of breeding, art reveals a lot about our furry friends. While I learn much about dogs by themselves, the way we represent them also says a lot about our society. Do we see animals as more than us in some way and less in others? Is a dog painting really about the …

Centro Cultural Morab Wera, Deisy Natalia Rojas Corso, Alicia Fernanda Tinjacá Del Castillo

Arquitectura

Este proyecto de grado busca como ejercicio proponer un centro cultural productivo en el contexto del barrio La Ladera de la comuna 8 en Medellín, la intervención busca generar un espacio para resignificar la cultura de la comunidad Embera Katío que viene desplazada desde el alto de Andágueda en el Choco y actualmente vive en hacinamiento en el casco urbano. La investigación se genera desde el análisis de las comunidades indígenas en Colombia y su contexto habitacional en su territorio, luego nos enfocamos en la problemática de desplazamiento y sus condiciones habitacionales en Medellín para de esta forma proponer un …

Entrainment Processes For A Jet In Cross-Flow: The Quantification Of Turbulent Contributions And Their Importance On Accurate Modeling, Graham Asher Freedland

Dissertations and Theses

A jet in cross flow (JICF) is examined experimentally by injecting a stream of air into crossing fluid with an aim into quantifying entrainment process and downstream evolution. The behavior of JICF is important to fields ranging from turbine-blade cooling to smokestack pollution and volcanic eruption dynamics. Existing simplified volcanic plume models are tested; most importantly, the near-field contributions of complex interconnected vortex systems, which present significant uncertainties because they assume negligible turbulence. While jets in irrotational cross-flow have been investigated, this analysis has focused on the interaction between a turbulent jet in low and highly turbulent cross-flow created by …

Very Light Jet Trainer (Vlj) - Phoenix Iv, Saxton Robinson, Eric Gentry, Daniyel Holmes, Navee Cheng

Senior Design Project For Engineers

This project was pursued to bring another possible solution to a major problem within the pilot training industry. When it comes to pilots training with aircraft, they must often use repurposed older aircraft to log their training hours. With few options when it comes to aircraft that are designed specifically for training, we have researched, modeled, and simulated tests for our own trainer jet to add to the market. The aircraft was designed to seat 4-8 people (1-2 for crew and 2-6 for passengers), weigh less than 10,000 lbs., have a range of about 1195.5 nautical miles, have a max …

Experimental And Numerical Study Of Drag Reduction On Elliptical Cylinders Using Surface Grooves, Michael T. Brocker, David J. Mcdonell, Drake L. Pensworth, Joshua J. Swimm

Channels: Where Disciplines Meet

Drag reduction on an object subject to external flow remains a topic of interest due to a wide range of applications. Previous studies showed that grooves on the surface of a circular cylinder lead to drag reduction, which had thus been applied to save energy in various implementations. In the present study, the effects of longitudinal surface grooves with respect to drag reduction on circular and elliptical cylinders were experimentally explored through resin additive manufacturing and a wind tunnel. Significant drag reduction originated by surface grooves was observed. In conjunction with experimental investigations, numerical analyses were performed with computational fluid …