Since the production of scallop aquaculture in Japan has increased largely, the automatic drilling machines has been used by the almost aquaculture bodies. Because of shell shape varying on size by growth and non automatic control mechanism built in drilling machines, severe problem has occurred that the machines always can not succeed to make a hole in the ear portion on a shell as expected. In this paper, the three respectable drilling areas were defined near by the byssal notch and by the ligament on the anterior ear of a shell. After confirmed of these parts obeying allometric growth, the successful rate (P) to drilling was estimated by some geometrical non-dimensioned parameters based on the vertical shell height (VH). The results of simulation were revealed as follows. 1) Near by the byssal notch : P was over 70% in case of VH over 60mm with 1.4-2.0 mm diameter of a drill chip (d), and P became up to 92% with VH=70mm and d = 1.6mm as normal use. 2) On the anterior ear : P reached to over 99. 6% with VH=40-55mm and d=1. 5- 2.0mm, also P showed to 99. 9% with VH=50mm and d=1.6mm for nomal use. 3) By the ligament : P was ranged from 30 to 77%, especially, P=70% under the nomal operation as same as 2). To locate the center of a drill chip according to the vertical shell height would rise up the successful rate to drilling through the ear part on a shell more higher than now.

抄録全体を表示

In the field of aviation, it is argued the necessity of the wide area DGPS that is a new system demanding highly precise positioning accuracy. This new system has the available range of over 1000-km around the reference station, and practical use begins to be investigated. It is expected that an idea of this wide area DGPS that will be applied to the sea and the ground in the future. In this study, We paid attention to influence caused to the position accuracy of DGPS in the wide area. The influence could be made clear in the simulation and the experiment. The simulation confirmed the delay of the correction value confirmed to influence the positioning accuracy. The positioning accuracy was found a tendency to deteriorate in a ratio of 0.0031m/sec2 according to the delay time. In the observation, several medium frequency beacon DGPS station data were used. The results of these observation, the distance between the reference station and users (it is called base line length) was confirmed to influence the effect of DGPS positioning. It became clear that the position error increases in proportion to the base line length at the rate of only a few 0.12m/100km. These results show the effectiveness of the wide area DGPS.

抄録全体を表示

本論文は油と水からなる二層流体の刃型堰越流に関する研究である。これはまた,越流堰を備えたタンクで海面に流出した油を回収する際,堰を越流してタンクに流入する油と海水の流量を推算するための基礎的研究である。ここでは,油のみが堰を越流する場合について,エネルギー式に基づく解析解と運動量式に基づく解析解を求め,実験値と比較した。後者が前者に比べ,実験結果をよりよく再現することができた。また,油と水の堰付着面に働く表面張力は油面低下による水面の上昇高に影響することが示唆された。

抄録全体を表示

135GT型まき網漁船の操業時における網船の鐶締めワイヤー張力の勤的制御を行うための第一段階とし て,ワイヤー張力が最も大きく,船体横傾斜も大きいと言われる鐶が閉まる前後状態において,その入出力 関係に対し非線形な応答関係を想定し,ニューラルネットワークモデルを用いて張力の推定を行った場合の 有効性について模型実験(ワイヤーの巻き上げスピードは無し)を行い検討した。その結果,線形モデルで は推定が難しいとされる波がうねる様な状況においても,ワイヤー張力変動を良く推定しており,非線形性 の強い横波状態におけるまき網漁船の鐶締めワイヤー張力の応答系に,ニューラルネットワークモデルを適 用することの有効性が確認された。

抄録全体を表示

The purpose of this study is to investigate cause of engine trouble conceming valve-seizure occurred on main engine of Tokyo university of fisheries, the research and training vessel Shinyo Maru. For this purpose, an experimental measurement of the valve stem clearance had been carried out when the valve stem guide was inserted into the cylinder cover. The results showed that the mean value of valve stem clearance reduction was 0.008 mm. The valve stem clearance of measurement value has lowered than the minimum value (0.06.mm) of maker recommendation. It was confirmed that valve-seizure in main engine could cause a dangerous operation. By taking point of view to prevent the engine trouble, these results lead to the suggestion that the valve stem guide should be finished accurately to the desired inside diameter with hand reamer, when the valve stem guide was changed.

抄録全体を表示

Numerical experiments were conducted to estimate the change of flow condition and the distribution of phytoplankton and nutrient by a submerged structure for upwelling in vertically 2-D steady flow field, using a coupled physical-biological model with changing parameters which are inflow velocity and turbulent diffusion coefficient. Nutrient uptake and the loss of phytoplankton including physiological death, exudation of organic substances and predation by zooplankton are considered as biological terms in the goveming equations. The computational domain is 2km long and 50.5m deep. The structure with 10m height is set lkm downstream from the inflow boundary. As increasing the inflow velocity, the phytoplankton decreases in the upper and middle layers and, on the contrary, nutrients increases. However, they reaches certain values when the inflow velocity is over 0.3m/s. Biological tems are dominant in the surface layer. On the other hand, the physical terms (advection and diffusion) are dominant in the bottom layer. In the middle layer, the increment by nutrient uptake balances with decrease by advection, diffusion and the loss.

抄録全体を表示

The authors investigated inboard lighting-one of residential environment elements-of the fisheries training ship. The reflective properties of the ceiling and wall decrease year by year. As the average age of the crew members rises, there is an increased desire for better lighting. The lighting problem tends to be neglected in favor of environmental factors such as noise and vibration. Nonetheless, it is necessary to set a recommended level of illumination for the ship which will offer a comfortable and adequate inboard environment. Authors regard that lighting equipment should be upgraded within 10 years of construction, if economically possible, in order to maintain a positive inboard environment.

抄録全体を表示

練習船北星丸によって, CPP翼角およびプロペラ回転数による船速の制御に関する一連の実船試験を実施 した。これら翼角および回転数の組み合わせを変えた条件の下で航走試験を行い,その時の船速および主機 関の燃料消費量を計測した。これらのデータから,翼角と船速の関係を燃料消費量と回転数をパラメータと して定め,本研究では特にこの関係を等船速線として表した。これより,減速することなく主機関の燃料消 費量を減ずるための,翼角最適制御方法について検討した。本研究の方法により同一船速において約8%の 燃料節約が可能である事が分かった。

抄録全体を表示

Deep sea water has been tried to be used actively in fisheries for increasing basic production of sea area. It is requested that the deep sea water must be lifted up to photic zone. This paper presents the theory and the numerical calculation program about buoyant jets in quiescent Stratified ambient fluids. As the operative example, assuming a jet spouted out river water from a pipe at sea bottom, the rising height and discharge of the jet are calculated by the program.

抄録全体を表示