Ocean Engineering Commons^™

Parametric Analyses Of The Dynamic Response And Fatigue Life Of A Compliant Vertical Access Riser With Internal Flow, Fuheng Li, Haiyan Guo, Xiaomin Li, Zhen Liu, Honglu Gu, Peng Cui

Journal of Marine Science and Technology–Taiwan

Subsea interventions on wellheads can be directly performed from a platform using a compliant vertical access riser (CVAR), thereby incurring tremendous economic benefits. The dynamic response and the fatigue damage of a CVAR subjected to regular waves are important for assessing its application feasibility. Therefore, a reasonable numerical model is presented for assessing the damage to a CVAR considering the internal flow using the slender rod theory. The finite element method combined with a Newmark-β scheme is employed to discretize the equations and update the time integration. The Palmgren-Miner rule is applied for fatigue life prediction, focusing on the wave-induced …

Using The Inverse Method To Investigate Flow Models For Mixed Convection Of Annular Finned Tube Heat Exchanger, Han-Taw Chen, Cheng-Hui You, Wei-Lun Hsu, Jiang-Ren Chang

Journal of Marine Science and Technology–Taiwan

The inverse heat conduction method (IHCM) and three-dimensional (3D) computational fluid dynamic (CFD) in combination with are used to select the appropriate flow model and near-wall treatment for the mixed convection of the annular finned tube heat exchanger. Thus, the numerical results obtained by all k-ε models and near-wall treatments are yielded for 4 m/s ≤ Va ≤ 5 m/s. First, IHCM combined with is applied to estimate and Q values. The obtained estimates of and Q are used as reference values for CFD. The results show that the Tk and results obtained by the standard (STD) k-ε model with …

Prediction Of Remaining Useful Life Of Wind Turbine Shaft Bearings Using Machine Learning, Jinsiang Shaw, Bingjie Wu

Journal of Marine Science and Technology–Taiwan

Wind turbines are a major trend in the current green energy market. Wind energy is abundant, and if utilized properly, can result in significant reductions in carbon emissions. Therefore, the development of wind power systems is urgently required. However, wind turbines are mainly built in unmanned areas. Regular inspections require substantial manpower and material resources, and doubts regarding the accuracy of the inspected data may occur. Therefore, it is necessary to establish an automatic diagnostic method for determining the remaining useful life (RUL) of a wind turbine to facilitate predictive maintenance. In this study, a multi-class support vector machine (SVM) …

Supply Chain Management For Superyacht Construction In Taiwan, Chun Pong Wong

Journal of Marine Science and Technology–Taiwan

In the last 20 years, Taiwan’s superyacht construction industry has performed well in the global market; however, numerous yacht builders still practice traditional supply chain management (SCM), which is often inefficient and regularly leads to time and cost overruns. This study aimed to answer two research questions: 1) what SCM challenges does the superyacht construction industry face? and 2) what SCM strategies and practices should be adopted to improve the efficacy and profitability of superyacht construction companies?

Numerous studies have explored supply chains (SCs) and SCM, but few have focused on the superyacht construction industry. Superyacht construction projects are highly …

The Impact Of Variable Curing Conditions On The Properties And Microstructures Of Mixtures Of Ground Granulated Blast Furnace Slag And Circulating Q1 Fluidized Bed Combustion Ash, Shao-Heng Hsieh, Wei-Chung Yeih, Ran Huang

Journal of Marine Science and Technology–Taiwan

The use of Portland cement, an important construction material, is encountering growing challenges because of its adverse environmental impacts. In this study, a new hydration system without Portland cement, which blends ground granulated blast furnace slag (GGBFS) and circulating fluidized bed combustion (CFBC) ash, was developed and tested. The variables included the effect of different types of CFBC ash, the mass ratios between CFBC ash and GGBFS, and different curing temperatures. The mortar properties were determined through the compressive strength test, absorption test, shrinkage test, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The main results were as follows: …

A Marine Gis-Based Alert System To Prevent Vessels Collision With Offshore Platforms, Sheng-Long Kao, Ki-Yin Chang, Tai-Wen Hsu

Journal of Marine Science and Technology–Taiwan

How to effectively use an intelligent aid-to-navigation (AtoN) to prevent ships from accidentally colliding with offshore marine platforms (OMPs) is an important issue for maritime environment. This study proposes a novel collision alert system with three components to process Automatic Identification System (AIS) data in the cloud and broadcast AtoNs to ships in order to avoid collision with OMPs. The first component receives as input fuzzy linguistic variables (vessel size, relative speed, and approach distance) from the AIS data and calculates the radius of the guarding ring. The second component serves a Marine GIS (MGIS), where the system simulates the …

Effectiveness Against White Sharks Of The Rpela Personal Shark Deterrent Device Designed For Surfers, Craig Blount, Dan Pygas, Marcus P. Lincoln Smith, Daryl P. Mcphee, Colby Bignell, Ocean Ramsey

Journal of Marine Science and Technology–Taiwan

Many shark bites to humans, including fatalities, have involved surfers. Various personal shark deterrents are commercially available to surfers, including Rpela v2, which is a battery-powered device fitted to a surfboard. It produces an electric field around the surfer aimed at deterring sharks from approaching or biting by disrupting their electro-reception organs. The device was tested on white sharks (Carcharodon carcharias) at Salisbury Island, Western Australia. In total, 46 trials were done with the Rpela v2 either active or not active to determine the device’s effect on sharks’ response to a floating board with fish bait attached (to tempt a …

Inter-Annual Changes Of Water Temperature In The Southern South China Sea's Continental Shelf: The Influence Of Enso On Malaysian Waters, Afifi Johari, Mohd Fadzil Akhir, Muhammad Naim Satar, Zuraini Zainol, Guo Jingsong

Journal of Marine Science and Technology–Taiwan

An extensive amount of data from the World Ocean Database (WOD) that covers the southern South China Sea (SSCS) were analysed to study the long-term trends and variations of the El-Nino Southern Oscillation (ENSO) event. The WOD data were selected from 1951 to 2010, which included the area within 0–10 °N and 100–117 °E. El-Nino and La-Nina anomaly results showed that the sea surface temperature anomalies (SSTa) trend of SSCS was higher during offset-El-Nino years and lower during offset-La-Nina years. Besides, the inter-annual vertical water temperature profile revealed that the deepening of the warmer water temperature occurred in February and …

The Eumedonine Genera Eumedonus H. Milne Edwards, 1834, And Gonatonotus White, 1847 (Crustacea: Brachyura: Pilumnidae) In Taiwan, Peter K. L Ng, Chia-Wei Lin

Journal of Marine Science and Technology–Taiwan

Two species of eumedonine crabs, Eumedonus zebra Alcock, 1895, and Gonatonotus nasutus Chia & Ng, 2000, are recorded from Taiwan, the former for the first time. Both are also new genera records for the island. Notes on variation are noted and their taxonomy briefly treated. The number of eumedonine species, all of which are obligate symbionts on echinoderms, known from the island is now seven genera and seven species.

An Analysis Of Consumer Evaluations Of The “Tagonoura Shirasu” Certification Under The Japan Geographical Indication Protection System, Yu-Heng Lu, Takahiro Sajiki

Journal of Marine Science and Technology–Taiwan

Over time, the Geographical Indication (GI) protection system has been independently adopted in more than 100 countries worldwide. In Japan, the GI protection system has been operating since 2015 in response to a growing interest in local brands. Therefore, based on a questionnaire survey, we econometrically analyze the consumer evaluation of Shizuoka Prefecture’s Shirasu “Tagonoura Shirasu,” which is registered under the GI protection system. Shirasu is a collective term for long and narrow larvae such as anchovy (Engraulis japonicus), sardine (Sardinops melanostictus), or red-eye round herring (Etrumeus sadina). Based on the contingent valuation method, we clarified that consumers' additional willingness …

A Two-Stage Approach To Integrate Vessel Geo-Tracking Data And Logbooks For Monitoring Fishing Activity Of Coastal Fisheries In Waters Off Northwestern Taiwan, Yi-Jou Lee, Nan-Jay Su, Cheng-Hsin Liao, Wei-Chuan Chiang, Chun-Huei Li

Journal of Marine Science and Technology–Taiwan

Catch and fishing effort data are fundamental information to stock assessment and fisheries management, but difficult to obtain without the support of administration and sound fishery data collection system. This study integrated various sources of data from a simplified vessel geo-tracking system and logbooks from interviews with captains of coastal gillnet fisheries. We developed a two-step approach based on hierarchical cluster analysis to characterize the operation patterns and infer the fishing activities of the fishery. Results showed that the fishing effort in terms of operation duration could be estimated precisely for various vessel sizes, with catch composition and harvest information …

Effect Of Chlorine Dioxide On The Removal Of Sulfadimethoxine And Sulfamethoxazole In Freshwater And Seawater, Zhen-Hao Liao, Dai-Chee Ng, Yu-Sheng Wu, Fan Hua Nan

Journal of Marine Science and Technology–Taiwan

This study aimed to understand the fate of sulfonamides (SAs) under dark condition in a laboratory-scale aquatic system, and evaluate the removal of SAs by using Chlorine dioxide. Based on the mass spectrometry quantification, our results have shown that two sulfonamides were transformed at very slow rate in the dark. The 180 day degradation efficiencies (%) of sulfadimethoxine (SDM) in freshwater and seawater were 6.37 ± 2.56 and 4.38 ± 3.43, respectively, while those of sulfamethoxazole (SMX) in freshwater and seawater were 7.81 ± 2.15 and 6.60 ± 2.69, respectively. In the treatment of Chlorine dioxide for the removal of …

Long-Term Observations Of Interannual And Decadal Variation Of Sea Surface Temperature In The Taiwan Strait, Ming-An Lee, Wei-Po Huang, Yi-Lo Shen, Jinn-Shing Weng, Bambang Semedi, Yi-Chen Wang, Jui-Wen Chan

Journal of Marine Science and Technology–Taiwan

Long-term observations of interannual and decadal variation of sea surface temperature (SST) in the Taiwan Strait (TS) were studied for the period 1870–2018; the climatology data were obtained from the Met Office Hadley Centre, UK. In the study period, the highest annual mean and lowest SST observed were 25.3°C in 1998 and 22.4°C in 1919, respectively. Six distinct regimes were identified. The first regime of fairly stable or slightly cooling SST lasted through the 1920s. The two regime shifts of 1919 to 1945 and 1976–1977 to 1998 led to the two fast warming trends of 2.0°C in 26 years, from …

Experimental Investigation And Modeling Of The Response Surface Methodology For The Optimization Of A Multiloop Heat Pipe, Dar-Sun Liou

Journal of Marine Science and Technology–Taiwan

Considering thermohydrodynamic instabilities in the design of cooling systems has become a trend, which has led to the evolution of thermal management. However, such instabilities, which cause flow perturbations, are difficult to explain by using physical theories. The aim of this study was to use a parameter-based modeling technique, namely the response surface methodology (RSM), to characterize the dynamics of multiloop heat pipes (MLHPs) under various heat loads. The RSM, which is based on statistics, was used to determine the relationship between the design parameters and thermal responses of MLHPs, which are represented using polynomials. Th aim of our RSM …

Supply Chain Inventory Model With Markov Chain Demand, Zhi-Ping Lin, Su-Ping Ho

Journal of Marine Science and Technology–Taiwan

This study aims to develop a new one-vendor multiple-buyers integrated inventory model. We believe that our proposed model can forecast the demand of all buyers in the coming future by using data that have already existed and to minimize the total cost-for both buyers and vendors. In recent days, the Markov chain approach has played one of the critical methods of demand forecasting in the Supply Chain Management (SCM) field. The proposed model of this study is to analysis the demand of all buyers in one specific season that was impacted by the demand in the same season from last …

Fire Resistance Of Steel Connectors Of Precast Lightweight Concrete Walls, Jen-Hao Chi, Maochieh Chi, Yue-Lin Huang

Journal of Marine Science and Technology–Taiwan

In this study the fire test was performed to investigate the mechanic behaviors and failure patterns of precast normal weight concrete (NWC) and lightweight concrete (LWC) walls with three types of commonly used steel connectors, namely dry (61), wet (81), and bearing (56E) connectors. For the LWC wall specimens, on lateral application of tension, the cracking load values of the dry, wet, and bearing-type connectors were 95.1%, 86.3%, and 83.0%, respectively, of the original loads, and their ultimate load values were 81.6%, 90.7%, and 85.0%, respectively, of the original. In the shearing test after the fire resistance test, the cracking …

Differential Evolution Algorithm For Ship Path Planning In Open Waters, Yu-Tao Kang, Wei-Jiong Chen, Jin-Hui Wang

Journal of Marine Science and Technology–Taiwan

A general approach to the derivation of simple yet accurate formulas for identifying bandpass nonlinear channels in or-thogonal frequency-division multiplexing (OFDM) systems is proposed in this paper. The OFDM is an widely adopted tech-nique for wideband communication applications. An OFDM signal could be highly vulnerable to nonlinearities in a com-munication link. This makes proper estimation of the nonlin-ear channel essential for an OFDM system. A nonlinear bandpass communication channel is commonly described by a complex Voletrra series, in which the task of nonlinear channel identification is to determine the Volterra kernels. This task can become very difficult when the order …

Integrated Simulation Of Virtual Prototypes And Control Algorithms Of Unmanned Surface Vehicles Based On A Robot Operating System, Hye-Won Lee, Joo-Hyun Woo, Myung-Il Roh, Seung-Ho Ham, Luman Zhao, Sol Ha, Nak-Wan Kim, Chan-Woo Yu

Journal of Marine Science and Technology–Taiwan

Unmanned surface vehicles (USVs) require autonomous software with a high level of liberalization and automation to complete various missions. Therefore, experimental verification and validation of this software at the initial design stage are essential. However, such experiments are impossible before the actual hardware is developed, and the creation of an external environment for the mission requires substantial cost and time. In this study, virtual prototypes of the mission environment and hardware for the USV are developed. Then, a simulation environment for testing the control algorithms in the autonomous software is constructed. Data communication with the USV hardware is necessary for …

Identification Of Nonlinear Channels In Bandpass Communication Systems With Ofdm Inputs, Jen-Ho Cheng, Ching-Hsiang Tseng

Journal of Marine Science and Technology–Taiwan

A general approach to the derivation of simple yet accurate formulas for identifying bandpass nonlinear channels in or-thogonal frequency-division multiplexing (OFDM) systems is proposed in this paper. The OFDM is an widely adopted tech-nique for wideband communication applications. An OFDM signal could be highly vulnerable to nonlinearities in a com-munication link. This makes proper estimation of the nonlin-ear channel essential for an OFDM system. A nonlinear bandpass communication channel is commonly described by a complex Voletrra series, in which the task of nonlinear channel identification is to determine the Volterra kernels. This task can become very difficult when the order …

Comparison Of Concrete And Steel Jacket Methods For Reinforcing A Concrete Bridge Pier By Numerical And Experimental Studies, Hadi Faghihmaleki

Makara Journal of Technology

Various rehabilitation and strengthening procedures have been developed in recent decades. A study to determine which methods can be implemented to increase the useful life of the bridge before strengthening must be performed. In this study, the seismic behavior of a reinforced concrete bridge pier with dimension 3.5 × 3.5 m, which was reinforced by two steel and a concrete jacket, was investigated. Nonlinear geometric models and materials were analyzed to estimate the seismic parameters of the pier. Results show an increase in energy absorption, ultimate strength, and ductility for the steel jacket, as well as a greater increase in …