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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

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. Source

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

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. Source

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

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. Source

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

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. Source

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

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. Source

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