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%.

抄録全体を表示

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]

抄録全体を表示

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.

抄録全体を表示

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.

抄録全体を表示

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.

抄録全体を表示

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.

抄録全体を表示

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.

抄録全体を表示

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.

抄録全体を表示

回流水槽は船舶試験のみならず,漁具の設計や開発,沿岸域造成等の研究に広く利用されてきた。東京海洋大学海洋科学部に国内初の水平循環型回流水槽が水圏科学フィールド教育研究センター・館山ステーション(旧館山実習場)に設置されたのは1951年である。その後, 1978年にベルト回転式移動底付きの回流水槽が作られ, 2年後の1980年には底面境界層吸込装置付きの大型回流水槽が建造された。また,田内の漁網の模型比較則が公表された翌年の1935年に旧東京水産大学前身の水産講習所に流水式試験水槽が設置され, 1945年の米軍による接収とともに廃棄されるまで漁具の模型試験に活用されていた。ここでは,昨年3月に建造された本学海洋科学部における4代目の新しい回流水槽の概要と主な特徴を述べるとともに,測定部の流速分布と自由表面の平滑性,表面および底面の加速装置による流速分布の改善効果,加速度流および往復振動流などの計測結果について論ずる。

抄録全体を表示

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.

抄録全体を表示