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Wave power extraction by a dual OWC chambers over an undulated bottom

Renewable Energy 2023年第1期216卷

作者： Naik, Nikita Gayathri, R. Behera, H. Tsai, Chia-Cheng Department of Mathematics SRM Institute of Science and Technology Tamil Nadu Kattankulathur603203 India Center of Excellence for Ocean Engineering National Taiwan Ocean University Keelung202301 Taiwan Bachelor Degree Program in Ocean Engineering and Technology National Taiwan Ocean University Keelung202301 Taiwan

The impacts of sloping bottom and slanted impenetrable wall on dual oscillating water columns (OWCs) with a slanted front wall are examined. To tackle the physical model, a coupled eigenfunction expansion — boundary element system is employed. The concept is based on employing the anticipated amplification of scattered and reflected wave fields generated by the existence of sloping walls to enhance the absorption of wave power driven by the walls’ wave reflections. The study concludes that 100% efficiency occurs for smaller incident wave angles. It is also observed that compared with short waves, the efficiency of the device is more in the long-wave region. OWCs are observed to be more effective over the undulating bottom and sloping impermeable wall with an increased spacing between the water columns and the second OWC to the impermeable wall. Additionally, the chambers’ width and the sloping bottom angle are vital parameters for higher power extraction from the OWCs. Furthermore, the optimal values of slope bottom and wall inclination may be employed to build and implement an efficient OWC device. Moreover, the proposed model can also be used as a breakwater to protect the coastline. © 2023 Elsevier Ltd

关键词： Boundary element method

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Water wave interaction with ice-sheet of variable geometry in the presence of uniform current

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Physics of Fluids 2024年第4期36卷 042108-042108页

作者： Aggarwal, Akshita Barman, Koushik Kanti Martha, Subash Chandra Tsai, Chia-Cheng Department of Mathematics Indian Institute of Technology Rupnagar Punjab Ropar140001 India Center of Excellence for Ocean Engineering National Taiwan Ocean University Keelung202301 Taiwan Bachelor Degree Program in Ocean Engineering and Technology Center of Excellence for Ocean Engineering National Taiwan Ocean University Keelung202301 Taiwan

We propose an asymptotic method to solve the problem of flexural-gravity wave scattering by an ice sheet of variable geometry in the presence of uniform currents. The significance of the article resides in the development of first and second-order solutions via the use of asymptotic expansion and the Fourier transform technique. We consider two different shape functions for the plate geometry, namely, Gaussian and Gaussian oscillatory. For both shape functions, the first and second-order solutions result in a major impact of depth Froude numbers in hydrodynamic coefficients, emphasizing the crucial function of the higher-order solutions in understanding the current responsiveness. We also observe the occurrence of Bragg resonance for the Gaussian oscillatory shape. The depth Froude number alters the frequency of wave components that are most reflected, and wave action conservation causes a rise in the energy of reflected waves. The depth Froude numbers can induce a unique minimum in reflection coefficient, which is close to 0. An examination of plate deflection reveals that the elevation amplitude is substantially higher near the point where there is a peak of elastic plate's shape. The pressure exerted by the plate is also concentrated near this point, highlighting the significance of the elastic plate's shape. The collective numerical observations for both shapes provide insight into resonance phenomena, the role of plate shape, and the intricate relationship between wave characteristics and varying plate properties. The findings from this study could assist geologists and marine engineers in designing and managing ice sheets, ports, and harbor infrastructure. © 2024 Author(s).

关键词： Gaussian distribution

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Greenhouse gas emissions reduction and energy savings for a dredger at port area using hybrid photovoltaic power system onboard

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Energy for Sustainable Development 2024年 78卷

作者： Wu, Chien-Hsing Wang, Hui-Chiao Chang, Horng-Yi Department of Marine Engineering National Taiwan Ocean University Keelung202301 Taiwan Bachelor Degree Program in Ocean Tourism Management National Taiwan Ocean University Keelung202301 Taiwan

For reducing greenhouse gas (GHG) emission and saving energy, a hybrid photovoltaic (PV) energy system comprised of grid-connect and off-grid modes was utilized on a dredger at emission control area (ECA) such as a port area. The experiments on this hybrid PV power system were carried out to evaluate the electric energy consumption of each equipment onboard in three operation modes (dredging, rest and idle) of dredger and to analyze the contribution of such a PV power system. The PV array had charging batteries in grid-connect mode and converted the PV power to alternating current (AC) directly during daytime period. At nighttime, the batteries could supply the electric power in off-grid mode. Even this dredger is no large free deck area for installing PV arrays onboard, the power conversion for PV array can offer about 1.0 % of total demand electric energy yearly. After evaluating the electric power consumption of each equipment onboard at different dredger operation mode, the proposed hybrid PV power system can offer 4.0 % (3.9 kWh by 96.8 kWh) of energy demand in grid-connect at rest mode and supply 100 % (29.85 kWh by 29.85 kWh) energy for dredger equipment in off-grid without diesel generator running at idle mode. This hybrid PV power system on the dredger has not only saved marine diesel oil (MDO) 2094.2 kg/year, reduced GHG of CO2 about 6455 kg/year, SOx about 3.942 kg/year and particulate matter (PM) around 1.97 kg/year but also reduced the diesel generator maintenance cost from stop running for 15 h/day and saved the cost of fuel (MDO) about USD 2128.5/year. The hybrid PV power system exhibited very effective efficiency of PV array and optimized the installation of batteries bank in ship with limited deck space at ECA and port area with high solar radiation density zone. © 2023 International Energy Initiative

关键词： Emission control

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Spermidine Carbon Quantum Dotsas an Alternative Antimicrobial Agent for Hatcheries Rearing Pacific White Shrimp (Litopenaeus Vannamei)

SSRN

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SSRN 2025年

作者： Lin, Hung-Yun Lin, Han-Tso Chiang, Yun-Ru Lu, Ya-Yun Pan, James Chen, Ming-Hsien Chuang, Jie-Cheng Lin, Hou-Ju Kuo, Wan-Ching Lin, Han-Jia Lin, John Han-You Bachelor Degree Program in Marine Biotechnology National Taiwan Ocean University Keelung City Taiwan Center of Excellence for the Oceans National Taiwan Ocean University Keelung City Taiwan Department of Biotechnology Ming Chuan University Taoyuan City Taiwan School of Veterinary Medicine National Taiwan University Taipei City Taiwan Department of Bilingual Taipei Fuhsing Private School Taipei City Taiwan Sheng Long Bio-tech International Company Long An Province Viet Nam Giant Bio Technology Incorporated New Taipei City Taiwan Department of Bioscience and Biotechnology National Taiwan Ocean University Keelung City Taiwan

Bacterial infections often constrain shrimp production in aquaculture installations. This study assessed the efficacy of a novel antibacterial agent, spermidine carbon quantum dots (spd-CQDs), in promoting the survival of Pacific white shrimp (Litopenaeus vannamei) during the hatching phase and early larval stages;in vitro assessments involved determining the bacteriostatic activity of spd-CQDs against Vibrio strains isolated form shrimps farm in Vietnam and Taiwan. An in vivo challenge was conducted by exposing shrimp larvae to the pathogenic Vibrio parahaemolyticus that causes acute hepatopancreatic necrosis disease (VpAHPND), with or without the inclusion of spd-CQDs in their pellet diet. Results indicate that the application of spd-CQDs significantly reduces Vibrio loads in shrimp hatcheries and enhances the survival rate of larvae in the challenge test. The subsequent analysis assessed the effects of administering spd-CQDs in live feed for broodstock, powder feed for shrimp larvae, and in the rearing water, which can maintain aqua environment quality, demonstrating its ability to maintain the quality of the aquaculture environment. Overall, spd-CQDs significantly reduced Vibrio loads and enhanced the larvae survival rate. This suggests that spd-CQDs could be an alternative to conventional antibiotics, paving the way for sustainable shrimp farming. Future research should address its long-term effects and broader applicability across aquaculture systems. © 2025, The Authors. All rights reserved.

关键词： Bactericides

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Study on the Application of Typhoon Experience Parameter Analysis in Taiwan’s Offshore Wind Farms

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Water (Switzerland) 2023年第14期15卷 2575页

作者： Fang, Hui-Ming Hsu, Hao-Teng Wang, Hsing-Yu Bachelor Degree Program in Ocean Engineering and Technology National Taiwan Ocean University Keelung20224 Taiwan Ship and Ocean Industries R&D Center Taipei251401 Taiwan Department of Shipping Technology National Kaohsiung University of Science and Technology Kaohsiung805301 Taiwan

Due to the rapid development of computers, researchers have made efforts since the 1990s to develop typhoon forecasting models and stochastic typhoon simulation models to assess typhoon disasters and risks. Typhoon forecasting models are primarily used to predict and track the movement of typhoons and provide warning information to the general public before landfall. Stochastic typhoon simulation models can assess extreme wind speeds and compensate for the limitations of current observations and simulation data length. Taiwan experiences approximately three to four typhoons yearly, of varying intensities and paths. Whether the marine meteorological data includes events of strong typhoon centers passing through will affect the results of frequency analysis. The development of offshore wind power in Taiwan is closely related to the unique marine meteorological conditions throughout the lifecycle stages, including wind farm site selection, feasibility studies, planning and design, construction and installation, operation and maintenance, and decommissioning. This study references relevant research and analyzes sixty-three scenarios using nine types of maximum storm wind speed radii and seven Holland-B parameters. The data from Japan Meteorological Agency Best Track Data (JMA BTD) is utilized, explicitly selecting 20 typhoon events after 2000 for wind speed simulation using a typhoon wind speed model. After validating the typhoon wind speeds with observation data from the Central Weather Bureau (CWB) in Hsinchu and the Longdong buoy, the technique of Monte Carlo simulation is utilized to generate synthetic typhoons randomly. The average of the relative absolute errors for the simulated maximum wind speeds is calculated, and through comprehensive evaluation, optimal parameter combinations ((Formula presented.), (Formula presented.)) are obtained. © 2023 by the authors.

关键词： Stochastic systems

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Application of Rogue Waves Simulation for Reef Coasts Risk Assessment

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SSRN 2023年

作者： Tseng, I-Fan Hsu, Chih-Hung Department of Marine Environment and Engineering National Sun Yat-sen University Kaohsiung80424 Taiwan Bachelor Degree Program in Ocean Engineering and Technology National Taiwan Ocean University Keelung202301 Taiwan

Coastal regions are crucial for human settlements, and comprehending the risks they pose is imperative. This study introduces a comprehensive risk assessment framework employing numerical simulations of rogue waves for reef coasts in Taiwan. This methodology integrates bathymetric data, wave conditions, and the FLOW-3D computational fluid dynamics model to replicate wave patterns and their evolution in nearshore areas. Such integration permits the assessment of rogue wave occurrence probability and associated hazard level ratings for designated reef coast sites in Taiwan. The study analyzed 30 reef coast locations, focusing specifically on the likelihood and hazard scores of rogue waves. An evaluation of historical wave data and simulation results revealed that zones with elevated rogue wave occurrence probabilities align with previous incident patterns. This framework offers invaluable insights into latent risks, thereby enhancing coastal safety and benefiting engineering strategies. © 2023, The Authors. All rights reserved.

关键词： Numerical models

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Bragg scattering of gravity waves by a sea bed of varying depth in the presence of uniform current covered by a floating membrane

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Physics of Fluids 2024年第1期36卷 012118-012118页

作者： Barman, Koushik Kanti Chanda, Ayan Tsai, Chia-Cheng Hsu, Tai-Wen Center of Excellence for Ocean Engineering National Taiwan Ocean University Keelung Taiwan Department of Ocean Engineering and Naval Architecture Indian Institute of Technology Kharagpur West Bengal Kharagpur India Bachelor Degree Program in Ocean Engineering and Technology National Taiwan Ocean University Keelung Taiwan Department of Harbor and River Engineering National Taiwan Ocean University Keelung202301 Taiwan

We present an asymptotic approach to solving the water wave scattering by undulating bottom topography in the presence of uniform currents where a flexible membrane covers the upper surface. The interest in this problem lies in the development of asymptotic solutions using the Fourier transform under the action of uniform currents. The method allows the physical processes involved in the sea-bed topography and membrane-covered surface and wave interactions to be studied. In particular, we identify the existence of Bragg resonance between gravity waves and the bottom ripples, which are associated with the reflection of incident wave energy. We consider the impacts of uniform current, and we highlight the central role of the asymptotic expansion method in the evolution of the response of current. For depth Froude number in the range of 0.4-0.7, the effects of bottom topography on Bragg resonance dominate. The current shifts the frequency of the most reflected wave components, and wave action conservation results in amplified reflected wave energies for the following currents. The theory developed in the frequency domain is illustrated in the time domain using discrete Fourier transform with the Joint North Sea Wave Observation Project (JONSWAP) spectrum [Hasselmann et al., J. Phys. oceanogr. 10, 1264 (1980)] to analyze wave propagation through the whole system. © 2024 Author(s).

关键词： Gravity waves

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Sizing the navy's strategic reserve of ozone-depleting substances

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NAVAL ENGINEERS JOURNAL 2000年第6期112卷 17-25页

作者： Breslin, DA Smith, DE Toms, GS [?]1David A. Breslin P.E. is the Director of Technical Operations for the Naval Surface Warfare Center and is the Chairperson of ASNE'S Committee on Environmental Engineering. He received a master of science degree in aerospace engineering from Virginia Polytechnic Institute (VPI) a master of engineering administration degree in industrial and systems engineering from VPI and a bachelor of engineering degree in mechanical engineering from Stevens Institute of Technology. From 1993 to 1997 he was the program manager of the Naval Sea Systems Command'S CFC & Halon Elimination Program and played a critical role in establishing the Navy'S strategic reserve of ozone-depleting substances. Because of his many efforts he received a Stratospheric Ozone Protection Award in 1995 from the U.S. Environmental Protection Agency in recognition of “exceptional contributions to global environmental protection”.

The domestic production of the most powerful Ozone-Depleting Substances (ODSs) has permanently ceased and the abundant supplies of a number of refrigerants, fire-fighting agents, and solvents, once taken for granted, are now a thing of the past. ne Navy has adopted a successful strategy for addressing the threat posed by the unavailability of ODSs. That strategy includes relying on a strategic reserve of ODSs. Considering that the strategic reserve will play a critical role in sustained fleet operations well into the next century, it is important to record the history of the reserve and to document lessons learned in order to educate future generations that may be faced with similar challenges. This is the second of three papers that will cover all aspects of the Navy's strategic reserve of ODSs. The first paper documented the history of the Navy's effort to size, establish, and monitor a reserve designed to support fleet operations until-the middle of the next century (1). This paper addresses in detail the process used to estimate the required size of the reserve, including the survey method, statistical analyses, and sizing algorithms. The third paper will discuss the development of the plan for monitoring the reserve including the control mechanisms, regression methods, and statistical-process-control techniques (2).

关键词： Survey Methodology Fleet management Refrigerants Ozone depleting substances strategic reserves

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Effects of aluminum content on oxidation behavior of W-Al nanolayer coatings

Effects of aluminum content on oxidation behavior of W-Al na...

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International Conference on engineering Tribology technology, ICETT 2014

作者： Sun-Hui, Yao Shang-Hsien, Hung Yen-Liang, Su Wen-Hsien, Kao Yueh-Feng, Lin Bachelor Degree Program in Technology Management Chang Jung Christian University Kway Jen Tainan71101 Taiwan Department of Mechanical Engineering National Chen Kung University Tainan70101 Taiwan Institute of Mechatronoptic System Chienkuo Technology University Zhanghua50094 Taiwan

ISBN: (纸本)9783038354581

A series of W-Al nanolayer coatings were deposited with varying content of aluminum from 0 at.% to 65 at.% by a unbalanced magnetron (UBM) sputtering system. The as-deposited coatings were investigated first. Then, the coatings were oxidized aiming to study their oxidation behavior. SEM, TEM, XRD, GDOS and nano-hardness tester were used. The results showed that the Al content had a significant effect on the performance of W-Al coatings. The hardness of as-deposited and oxidized coatings decreased with increasing Al content. The pure W coating was heavily oxidized. As the Al content increased, the oxidation decreased fast and then remained stable as the Al content was higher than 45at.%. The effects of formed oxides on hardness were discussed. © 2015 Trans Tech Publications, Switzerland.

关键词： Hardness

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Application of Unmanned Aerial VehicleeBased Infrared Images in Determining Characteristics of Sea Surface Temperature Distribution

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Journal of Marine Science and technology (Taiwan) 2023年第1期31卷 13-25页

作者： Wang, Hsing-Yu Fang, Hui-Ming Chiang, Yun-Chih Department of Shipping Technology College of Maritime National Kaohsiung University of Science and Technology Taiwan Bachelor Degree Program in Ocean Engineering and Technology National Taiwan Ocean University Taiwan Center for General Education Tzu Chi University Taiwan

This study investigated the temperature field of a body of water by using rotary-wing unmanned aerial vehicles (DJI Mavic 2 Enterprise Dual) comprising visible light and infrared cameras to determine sea temperature distribution. With a flight height of 150 metres, image overlap of 80%, and image resolution of 4.75 cm/pixel, the proposed method was more effective than the conventional portable conductivityetemperatureedepth device in rapidly measuring sea surface temperature and determining sea temperature distribution. The discharged heated water of the Hoping Power Plant traveled 100e330 metres from the wastewater outfall and then gradually diffused in the range of 100e490 metres before reaching a similar temperature to the background sea temperature. The diffusion of the thermal plume was mainly affected by regional marine meteorological conditions. © 2023 National Taiwan ocean University.

关键词： Unmanned aerial vehicles (UAV)

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