Journal of Marine Science and Technology-Taiwan

The Ocean Color Imager (OCI) onboard the ROCSAT-1 Satellite was employed to demonstrate its capability in monitoring sandstorm events around Mongolia and northwestern China where they have been occurring in great frequency over these past few years. The OCI measures the radiance from the visible to near infrared regions in six spectral channels. The radiance can be used to calculate the aerosol optical depth (AOD) of the atmosphere through an atmospheric correction algorithm. The variation in the AOD during January and February of 2001 is investigated in this study. A set of OCI images covering the Yellow Sea was selected for analysis. The results showed that the AOD values increased significantly after the sandstorms erupted, where its value was almost four times higher than before.

This study evaluated the impact of climate change on the water supply of the Shihmen reservoir in northern Taiwan. Five downscaled general circulation models that represent the daily meteorological data of 2046-2065 were adopted. The future inflow of the Shihmen reservoir was estimated using the tank model. Subsequently, the water supply risk under the given demand and operating conditions was simulated and assessed. Compared with 2004-2011, the average annual precipitation of the Shihmen watershed in 2046-2065 is lower, particularly during the wet season (May-October). Therefore, the risk to the water supply will increase in the first cropping season (from March to June) in the future. To reduce the risk of water shortage caused by public demand, irrigation fallowing during the cropping season is necessary

In this paper, the performance of a 2000-ton hybrid AIP system submarine is investigated by analyzing the weight, volume and efficiency of its propulsion system. The engine of the investigated AIP system employs a low temperature polymer electrolyte membrane fuel cell which makes use of the hydrogen and oxygen as the reactants. More specifically, the reactants of fuel cell in this study are considered from the combination of three fuel storage systems, methanol (MeOH), liquid hydrogen (LH2) and metal hydride (MH2), and two oxidant storage systems, liquid oxygen (LOX) and compressed oxygen (O2). Based on the assumed various daily propulsion load consumptions, a propulsion system of a 3500 kW diesel generator, a 300 kW fuel cell, and a 7500 kWh energy capacity Li-ion battery bank is determined. With the system installed in the submarine, the maximum designed endurance can reach a total of 26 days for the fuel cell using the combination of reactant LH2 + LOX, and the minimum designed endurance can be up to 10 days for using the reactant MH2 + O2. For submarine cruising at zero speed, the submerged endurance of the AIP system using reactant LH2 + LOX plus battery bank is 22.8 times of that using battery bank alone. This value will increase to 25.0 times for submarine cruising at 7.4 knots. At the cruising speed of 5.5 knots, the maximum submerged range of submarine increases a factor of 24.1 for fuel cell using the reactant of LH2 + LOX as compared with operation on battery bank alone. Therefore, the submerged endurance is substantial enhanced for using the combination of fuel cell and battery. In addition, the indiscretion ratio is zero for the AIP system submarine with a cruising speed below 7.1 knots; this can greatly reduce the submarine vulnerability. Based on the weight and volume analysis of the submarine equipped with a hybrid AIP system, the usage of the reactant LH2 + LOX is well suited for a small- to medium-sized 2000-ton submarine with a fuel cell system. Furthermore, using the reactant MeOH + LOX has the advantage for large-sized LT-PEMFC AIP system submarines.

In this paper, Grashof’s theorem is justified from the perspective of the occurrence of stationary configurations and uncertainty configurations of four-link chains. The link length relations at stationary configurations and uncertainty configurations are examined in detail based on the triangle inequality, and then the conditions for the existence of a crank and a change point are deduced.

A prototype C-band pyramidal horn antenna was fabricated after using High Frequency Structure Simulator (HFSS) software to simulate, analyze, and optimize the design parameters. The pyramidal horn antenna was designed to operate as a key detection component for disaster prevention and warning instruments in the domestic development of water-level radar sensor (WLRS). Experimental measurements showed the horn operating with a bandwidth of ~ 800 MHz from 5.4 GHz to 6.2 GHz with the central frequency at 5.8 GHz. The voltage standing wave ratio (VSWR) in the operating frequency range and the radiation pattern gains were measured to be smaller than 1.2 and larger than 16 dB, respectively. The experimental measurements compared well with the simulated results and met the design requirements.

Recently most maritime countries in the world have fitted automatic identification system (AIS) in vessel traffic services (VTS) in compliance with regulations of International Convention in order to identify ship name and collect ship information. Traditionally VTS operators use automatic radar plotting aids (ARPA) to get ship maneuvering information for preventing ships from navigational faults. Although the two equipments can provide similar functions for VTS, the operational theory of them is quite different. In this study an experimental observation was carried out by means of ARPA radar and AIS fitted in the building of Merchant Marine Department, NTOU. The detected information was analyzed for comparison of their difference on characteristics. Results reveal that AIS can detect target ships with wider area coverage, larger quantity and more voyage information than ARPA radar. The latter can provide an active monitor to detect small ships that can not be done by AIS. Consequently for navigation safety VTS operators must concentrate on ARPA radar in priority and use AIS as supplementary installation for identification of ships.