The purpose of this research is to obtain the optimum sampling period for evaluating solar photovoltaic generation beforehand. For this purpose, the solar radiation was measured over 1 year at the once per a week. The effect of the sampling period on the integral error of amount of solar radiation was analyzed, and the fractal analysis of the solar radiation was carried out. As a result, the following issues were clarified. Er=0.0117t and t=0.00201Qa+1.934 were obtained as a relational expressions of the sampling period (t) and the integral error (Er) in amount of solar radiation, and of the amount of solar radiation (Qa) and the sampling period (t). Upper limit in the optimum sampling period was the 236 seconds, when allowed integral error of amount of solar radiation was 3%.

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Estimating Nagasaki Maru's whirling motion at single anchor is very important for the Captain and deck officers. In order to prevent accidents such as direct contact with other ships and obstacles on the sea floor, we continuously observed the whirling motion at a single anchor by using the DGPS. The results are as follow. 1) At a Beaufort's wind scale (wind force henceforth) of 2 and under, the wind directed against the anchor chain side and a slow whirling of the bow was observed. 2) At a wind force between 3 and 4, a regular elliptic motion was observed. 3) At a wind force 5, a distorted figure 8 movement forming unequal lobes was observed. 4) At a wind force 6, an amplified movement during wind force 5 was observed. 5) At a wind force 7, the relative heading angle formed in both the right and left sides with respect to the wind direction became equal, and a maximum whirling-breadth of 82 meters was measured. 6) When Nagasaki Maru is anchored on a single chain, the following equation for the average distance of transverse movement "d" and degree of whirling "a" with respect to wind speed "v" was determined. Moreover, the maximum distance of transverse movement was determined as approximately 1.5 times the value of "d". d=k1_v a=k_2v+5 d : the average distance of transverse movement (m) k_1 : 2.0 [1/knot] v : wind speed (knot) a : degree of whirling (°) k_2 : 1.0 [1/knot]

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Some methods to quantify complexities of time series data are introduced in this paper to analyse roll motion of small fishing boats in irregular waves. This paper describes the resemblance between the chaotic time series data and the time series data of roll motion of small fishing boat in irregular waves which is the narrow-band random process.

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The evaluation of positioning accuracy by MF-DGPS in the high seas is described. The data for accuracy analysis were collected by training and research ships of Tokyo University of Marine Science and Technology. The analysis revealed that the propagation distance of pseudo range correction data depends on the transmitter output power of the DGPS station and the ionospheric condition with time. As regards the effective range of DGPS in the high seas, the baseline length was computed to be 700 to 1000 km.

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Recently, the heading device using the interference wave measurement of GPS, which is called "GPS compass" or "Satellite compass", was developed as a new application of GPS (Global Positioning System). In this study, two types of GPS compasses were compared with the ring laser gyrocompass (RLG compass) in order to evaluate the heading accuracy of GPS compass. Moreover, the heading ability experiment of GPS compass was performed by comparison with a gyrocompass on a small fishing boat. As a result of these experiments, it was clarified that GPS compass has sufficient heading accuracy equal to the gyrocompass.

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The objective of this study was to clarify the difference of light environmental condition between seaweed beds dominated by Sargassum horneri, Sargassum macrocarpum and Ecklonia kurome. Light irradiance inside and outside of the seaweed beds were measured at Hashira-jima island, in Hiroshima Bay, on November 29, 2002. To define the relationship between light environmental condition and biomass, the structure of S. horneri and S. macrocarpum beds were investigated. Light environmental conditions were compared by relative light irradiance normalized surface irradiance. The biomass of E. kurome was largest and S. horneri was smallest among the investigated species in this study. The attenuation of relative light irradiance outside of seaweed beds was exponential and attenuation coefficient ranged between 0.2m^<-1>1 to 0.28m^<-1>. Relative light irradiance in the S. horneri and S. macrocarpum beds also reduced exponentially from top to bottom surface of seaweed beds. The attenuation was clearer in S. horneri than S. macrocarpum. Relative light irradiance at the bottom of E. kurome bed normalized to the irradiance at the top of bed was 3.8%. Relative light irradiance at the bottom surface normalized to the irradiance of top of the S. horneri and S. macrocarpum beds were 9.5% and 13.6%, respectively and larger in S. horneri bed even though the biomass was smaller than S. macrocarpum bed. The attenuation and reduction of light irradiance by macroalgae closely agreed.

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The purpose of this study is to evaluate the characteristic of LED lighting system because the LED is assumed as the lighting system for the fishery in next generation. For this purpose, the spherical and the plane lighting system using high luminance LED were produced, and measurement of the luminous flux and the emitting heat quantity, lighting experiment under the low temperature were carried out. As a result, the following issues were clarified. Total lumen of the spherical lighting system of the 100mm diameter which installed 296 LEDs on the surface was correspondent to that of 36W incandescent lamp. The emitting heat quantity of the LED was 15% of the energy consumption, while that of 100W incandescent lamp was 68%. The luminance of the LED at -58 degrees C decreased 83% in comparison with that in the normal temperature.

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Aquatic conditions of shrimp ponds developed in a mangrove area in the Mekong delta of Vietnam are investigated and the physical mechanisms that form their aquatic environments are discussed. The mangrove canopies play an important role in the stabilization of water temperature in the shrimp ponds through day and night At night, the dissolved oxygen concentration in the shrimp ponds is reduced to the survival limit for shrimps, but it recovers owing to the photosynthesis of phytoplankton in the shrimp ponds. On the other hand, the opening of a sluice gate supplies a lot of oxygen to the shrimp ponds from a tidal creek which connects to the open sea. Furthermore, the aquatic environment of the shrimp ponds depends on hydraulic processes such as the density flow which is formed by saline water supplied from the tidal creek and the water mixing which is caused by the compound configuration of the shrimp ponds developed in the mangrove area.

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A new circulating water channel was constructed in Tokyo University of Marine Science and Technology in March, 2003. This circulating channel is a horizontal type one with a working section of 9.0m in length, 2.2m in width and 1.95m in deep. Flow velocity through the channel can be varied from 0.1 to 2.0m/s, and acceleration flow of 1.0-5.0cm/s^2. and reciprocating oscillation flow of velocity amplitude ±0.5m/s with 20 sec frequency can be obtained. Computer system is applied automatically to drive this channel, to control equipments and to analyze the measured data. The measurements of velocity distribution on the working section including near surface and bottom showed the deviation of velocity obtained in each measurement points was within ±2.0% to the mean velocity, besides within ±1.0% on the near center part. Moreover, uniform acceleration flow and reciprocating oscillation flow could be automatically controlled with input of only an objective velocity and an operating time. Steady wave height and water level fluctuation on free surface were no more than 1.5 mm and 2.0 mm in 1.5m/s of flow velocity, respectively. These higher hydrodynamic performances would enable precise model experiments for fishing nets, fishing boats and underwater structures in flow.

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It is well known that the precipitation and the temperature during the spawning season of sweetfish affect the catch in the next year. There should be the favourable precipitation for the catch as well as the favourable water temperature for sweetfish. The method evaluates the catch from the precipitation and the temperature during the spawning season of sweetfish considering these phenomena. This method is also an excellent prediction method of the catch of sweetfish, because the precipitation and the temperature can be easily obtained.

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