Ship and Ocean Industries Randnter

Taipei, Taiwan

Ship and Ocean Industries Randnter

Taipei, Taiwan
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Wu H.-T.,National Taiwan University | Wu H.-T.,Ship and Ocean Industries Randnter | Chen P.-T.,National Taiwan Ocean University
Journal of Marine Science and Technology (Taiwan) | Year: 2017

This paper presents a coupled FEM/BEM for solving fluid/ structure interactions under mono-frequency external loadings. The elastic structure is modeled by finite element method, and the acoustic loading is represented by boundary element method. Firstly, a semi-submerged thin shell sphere is selected as a numerical example. The numerical results are compared with the analytical solutions to verify the present method. And then, an existing vessel is selected to compute the responses of wetted surface acoustic pressures and normal velocities and, consequently, radiated underwater noise caused by the vibrating of hull structure. The results are also compared with measured data under the ship sea-trial and good correlations are obtained.

Chen S.-H.,Ship and Ocean Industries Randnter | Chung Y.-C.,Taipei Chengshih University of Science and Technology | Yang T.-Y.,Taipei Chengshih University of Science and Technology | Chiu Y.-J.,Taipei Chengshih University of Science and Technology | And 2 more authors.
ICSSE 2013 - IEEE International Conference on System Science and Engineering, Proceedings | Year: 2013

System integration is crucial to fuel cells. In addition to considering relative control rules and treatment of the reactants, the design and control of the balance of plant (BOP) are vitally important for a self-sustainable and optimized fuel cell system. In this study, a fuel cell control system is developed by utilizing an instrument-based system integration platform and sensor-less fuel concentration estimation and verification. A control measure is determined by both consumption and concentration change of the fuel. The feasibility of the sensor-less fuel concentration estimation is verified by experimental results. A testing platform, integrating software and hardware, which is used for the direct liquid fuel cell system, has developed in this study. It is an beneficial and flexible tool for developing relative controlling algorithms, evaluating efficiency of cells, or designing BOP of fuel cells. © 2013 IEEE.

Chan H.-C.,Ship and Ocean Industries Randnter | Jeff C.-H.W.,National Taiwan University | Chen C.-F.,National Taiwan University | Wei R.-C.,National Sun Yat - sen University
OCEANS 2013 MTS/IEEE Bergen: The Challenges of the Northern Dimension | Year: 2013

Internal solitary waves greatly impact the ocean environment as well as the underwater acoustic propagation. Most observed internal solitary waves are categorized as mode-1 waves. They could generate the surface wave breaking in the convergence zone and produce ocean noises. These ocean noises would be enhanced in the convergence zone and reduced in the divergence zone due to rough and smooth sea surface conditions, respectively. This study observed the sound source from surface wave breaking affected the high sonic bands between 100 Hz and 10K Hz. The maximum noise was around 10 dB increment at 1.5K Hz and coincided with the maximum convergence (downwelling), which agrees well with the theory. Strong horizontal currents induced by internal solitary waves would produce self-noise in the infra and low sonic bands below 300 Hz. © 2013 IEEE.

Lee Y.-J.,National Taiwan University | Ho C.-Y.,National Taiwan University | Huang Z.-Z.,Ship and Ocean Industries Randnter
Journal of Mechanics | Year: 2014

Floating offshore wind turbines (FOWTs) can be used to exploit the enormous wind energy present over deep waters. Numerous studies have examined the dynamics of FOWTs, but few have focused on validating numerical results with experimental results, particularly for a deep draught FOWT in regions with frequent tropical storms. For this study, we developed a computer code and conducted experiments with a scale model to validate the simulation results. The computer code was first verified by comparing the results with those of the International Energy Agency Wind Task 23. Numerical simulations were implemented in both the frequency domain and the time domain. A comparison of the numerical and experimental results of the scale model in high waves showed good agreement. The flexibility of blades and the tower did not observably affect the motion of the deep draft spar-type FOWT. Therefore, it can be ignored in the preliminary design. The pitch motion of the scale model was within 1°. Therefore, the spar-type FOWT may be an effective power source for regions with frequent tropical storms. Copyright © 2014 The Society of Theoretical and Applied Mechanics, R.O.C.

Chang A.,National Taiwan University | Cheng Y.-C.,National Taiwan University | Chen C.-F.,National Taiwan University | Chan H.-C.,Ship and Ocean Industries Randnter | Lin S.-F.,Industrial Technology Research Institute of Taiwan
2013 IEEE International Underwater Technology Symposium, UT 2013 | Year: 2013

State-of-the-Art noise prediction has been used to model noise emissions from industrial facilities, shipping activity in underwater environment to estimate noise level contours beyond the source area, and to determine specific impacts at potentially sensitive receptors, including marine mammals, etc. This paper presents the ambient noise modeling using adiabatic mode theory as acoustic propagation model to evaluate the noise statistics including temporal coherence and spatial variability offshore western Taiwan. In this model, the ocean model (Taiwan Coastal Ocean Nowcast/Forecast System, TCONFS, formulated on the basis of the Princeton Ocean Model) generating time varying/spatial dependent temperature profiles for water column variability, and geo-acoustic database are used as environmental inputs to this model. The modeling results demonstrate the temporal/spatial variability induced by time varying ocean model output, manifested by measured data. (This work is supported by National Science Council of Taiwan). © 2013 IEEE.

Fang C.C.,National Taiwan Ocean University | Wu H.T.,National Taiwan University | Wu H.T.,Ship and Ocean Industries Randnter
Journal of Taiwan Society of Naval Architects and Marine Engineers | Year: 2013

This paper demonstrates the results on the combination of 3D ship motion and wave loads program(HSC-3D) with finite element strength analysis of ship hull structures. The ship motion responses and wave loads of a large container ship in oblique waves have been calculated and compared by using three computer programs which are based on 2D strip method, 3D pulsating source distribution technique (3DP) and 3D translating-pulsating source distribution technique (3DT) respectively. An interface program has been developed to transfer the hydrodynamic pressures obtained from 3D Green function method to structural finite element model. Based on the linearised theory, this interface program transfers the hydrodynamic pressures on the wetted hull surface to the finite element model and converts to the nodal forces smoothly. The discrepancies between the total resultant hydrodynamic forces and inertia forces for the large container ship in waves have been discussed. Some comparison results and examples of structural analysis based on the hydrodynamic pressures calculated by 3DP and 3DT techniques have been shown and discussed in this study.

Lin T.-H.,National Taiwan University | Chou L.-S.,National Taiwan University | Chou L.-S.,Japan Science and Technology Agency | Akamatsu T.,Japan National Research Institute of Fisheries Engineering | And 2 more authors.
Journal of the Acoustical Society of America | Year: 2013

Most studies on tonal sounds extract contour parameters from fundamental frequencies. The presence of harmonics and the frequency distribution of multiple tonal sounds have not been well researched. To investigate the occurrence and frequency modulation of cetacean tonal sounds, the procedure of detecting the instantaneous frequency bandwidth of tonal spectral peaks was integrated within the local-max detector to extract adopted frequencies. The adopted frequencies, considered the representative frequencies of tonal sounds, are used to find the presence of harmonics and overlapping tonal sounds. The utility and detection performance are demonstrated on acoustic recordings of five species from two databases. The recordings of humpback dolphins showed a 75% detection rate with a 5% false detection rate, and recordings from the MobySound archive showed an 85% detection rate with a 5% false detection rate. These detections were achieved in signal-to-noise ratios of -12 to 21 dB. The parameters that measured the distribution of adopted frequency, as well as the prominence of harmonics and overlaps, indicate that the modulation of tonal sounds varied among different species and behaviors. This algorithm can be applied to studies on cetacean communication signals and long-term passive acoustic monitoring. © 2013 Acoustical Society of America.

Chan H.-C.,Ship and Ocean Industries Randnter | Chang M.-H.,Ship and Ocean Industries Randnter | Liu A.-T.,Ship and Ocean Industries Randnter | Chung C.-H.,Ship and Ocean Industries Randnter | And 2 more authors.
2013 IEEE International Underwater Technology Symposium, UT 2013 | Year: 2013

Offshore wind farm is a renewable energy that has been commercially operated in Europe over 3.8 GW capacities in 2011 and will be targeted upon 150 GW in 2030. Taiwan also plans to install 3 GW offshore wind farms in 2030. Thus, a number of condition assessments and engineering designs are being studied, such as the site selection, the wind turbines layout, the environmental impact assessment, the maritime engineering, the installation and maintenance fleets. In this paper, we carried out the winds and waves as the critical conditions of sea status for the installation of offshore wind turbines. The winds and waves data were collected by a data buoy which was deployed near the entrance of Taichung Harbor. The wind speeds were measured at 15 m above the sea surface. In the case study, we assumed a jack-up vessel will be used for installation of wind turbines. Then, some benchmarking conditions are filled into the assessment. For example, the conditions for operated criteria were suggested as wind speeds below 15 m/s and significant wave heights below 1.5 m in a water depth of 30 m. Moreover, a continuous working duration is considered as 15 hours for installation of a wind turbine from a tower, a nacelle, and blades. Eventually, the yearly available days for the wind turbine installation were assessed about 175 days. Different working modes, such as piling, cable laying, and maintenance, were discussed those yearly available days as well. From the operation and maintenance (O&M) supporting vessels working days (260 days), an offshore wind farm owned 50 wind turbines and each needs maintenance of 260 hours every year that was a benchmark scenario. The supporting vessels require 6 at least that had been estimated. © 2013 IEEE.

Chan H.-C.,Ship and Ocean Industries Randnter | Fang M.-E.,Ship and Ocean Industries Randnter | Chen S.-H.,Ship and Ocean Industries Randnter | Lin C.-H.,Ship and Ocean Industries Randnter | And 2 more authors.
OCEANS 2013 MTS/IEEE Bergen: The Challenges of the Northern Dimension | Year: 2013

The offshore wind energy is more economic than the otherwise renewable energy. Therefore, many countries have already owned the offshore wind farms or planned to develop in recent years. Taiwan is going to build the demonstration project including offshore wind turbines and meteorological masts in the western sea of Taiwan. Before installation of wind turbines, site selection and condition survey are request. However, monitoring of wind turbines and ambient environments are also needed to collect data for the operation and the maintenance in the offshore wind farms. We know that Taiwan is a high-risk area with frequent natural disasters, such as typhoons, earthquakes, and monsoon. While the foundation and infrastructure of wind farms are designed and manufactured by higher safety factors to reduce the damage, the environmental impact might increase as well. Generally, the meteorological masts are the main part of environmental monitoring in the offshore wind farms. According to the demonstration project of offshore wind farms in Taiwan, the meteorological masts need some instruments for ocean environmental observations, which are tidal levels, sea surface waves, sea currents, seawater temperatures, salinities, and densities. Most of specifications in those instruments are followed by the IEC International Standard 61400-12-1. Moreover, the demonstration project requests the developers, who are in charge of the meteorological masts have to provide a long term data of 5 years at least. Because those instruments need retrieved and calibrated every 6-12 months. For lower capital expense, we design a seabed-mounted junction box to connect all underwater instruments and reserved an extensive capability for a monitoring network in the future. Moreover, we also integrate more underwater instruments, such as hydrophone for underwater noise measurement and seismometer. Although most of the planned wind farms in Taiwan have avoided away the habitats of the Chinese White Dolphins (Sousa chinensis), the noise impacts are still concerned. Thus, the underwater noises include the piling noise, the shipping noises, the cable laying noises, and the wind turbine operation noises, all of which are highly emphasized in the strategy for environmental impact assessments and monitoring plans. The power supply for those instruments is designed to depend on the rechargeable batteries at the meteorological masts, so those subsystems are designed using low power consumptions. A fiber-optic cable is used for the power and data transmission between the junction box and the meteorological mast. All collected data would be preliminarily processed in the meteorological mast and then transmit via the wireless transmission system to the land station for the owners and end-users. In addition, an offsite back of archive data is planned as well. © 2013 IEEE.

Hsu K.-P.,Ship and Ocean Industries Randnter | Lin H.-H.,Ship and Ocean Industries Randnter | Chen S.-H.,Ship and Ocean Industries Randnter | Hsu H.-Y.,Ship and Ocean Industries Randnter | Chan H.-C.,Ship and Ocean Industries Randnter
Proceedings of the International Offshore and Polar Engineering Conference | Year: 2014

Marine and meteorological disasters are the real challenges that add the risks and costs on maritime engineering. More demands of marine observatory are increasing with the development of offshore wind farm and ocean energy. For issues of underwater environmental monitoring, the general sensors are included ADCP, CTD, wave gauge, hydrophone, seismometer, scouring detector, camera, and so on, all of which are considered as very utility monitoring. However, the marine observatory needs underwater junction boxes to integrate with sensors connection and power supply. This paper presents a technique on the adaptive power supply to be realizable in a junction box. This junction box is designed for connection with the environmental monitoring tower (met mast) in the offshore wind farm, and the deploy depths are over 30 meters. Copyright © 2014 by the International Society of Offshore and Polar Engineers (ISOPE).

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