マリンエンジニアリング
Online ISSN : 1884-3778
Print ISSN : 1346-1427
ISSN-L : 1346-1427
52 巻 , 1 号
選択された号の論文の23件中1~23を表示しています
巻頭言
特集 船底塗料と海洋環境に関する最新の話題
随想
技術資料
  • 加戸 隆介
    2017 年 52 巻 1 号 p. 3-8
    発行日: 2017/01/01
    公開日: 2018/03/14
    ジャーナル フリー

    Balanus grandula and Perforatus perforatus, two alien barnacles, have very recently extended their geographical ranges into northern Japan, part of the Far East. B. glandula is a cold water species inhabiting Alaska and Baja California, and P. perforatus is a warm water species living in coastal areas in the Mediterranean and the eastern Atlantic ranging from south-west Wales through West Africa. At the time of their discovery, the two species were already in high densities and dominant species in littoral and infralittoral zones in northern Japan. B. glandula and P. perforatus have extended their geographical distribution into north-eastern Hokkaido and the Pacific side of north-eastern Honshu respectively. Although barnacles are one of the most important marine fouling organisms, only little public attention is being given to these creatures. Therefore, this paper intends to provide morphological and geographical information about the two new alien species so that it will lead to a greater understanding of the present state of their invasions in Japan.

解説
技術資料
  • 室﨑 喬之, 野方 靖行
    2017 年 52 巻 1 号 p. 14-18
    発行日: 2017/01/01
    公開日: 2018/03/14
    ジャーナル フリー

      Recently, antifouling activities of micro-structured surfaces against marine sessile organisms have been reported. However, antifouling mechanisms of micro-structured surfaces have remained unclear until now. During their pre-settlement stage, cypris larvae of barnacles, which are popular marine sessile organisms, explore substrates with their two sensory organs. It is considered that the exploring behavior is intended to determine the most suitable substrate for their settlement.

      In this study, we investigated pre-settlement larval behavior of barnacle on micro-structured surfaces. The results found no settled cypris on self-assembled honeycomb-structured porous films. Furthermore, most of non-settled cypris quitted their exploration on the honeycomb-structured surface at an early stage.

解説
技術資料
  • 山下 桂司, 神谷 享子, 肖 瑛閣, 村野 大輔, 山根 和行
    2017 年 52 巻 1 号 p. 25-32
    発行日: 2017/01/01
    公開日: 2018/03/14
    ジャーナル フリー

    The effects of Kureha’s PGA (polyglycolic acid) resin on the settlement of the marine sessile organisms (actinulae of the hydroid, barnacle cyprids and epiphytic diatoms) were examined in the laboratory. For this settlement assay, larvae or diatoms were placed on PGA resin plates in the polystyrene test vessels containing filtered sea water, and their behaviors was observed through various microscopes. The results showed that the PGA resin plates clearly inhibited larval attachment, and diatoms’ settlement and surface-gliding behavior without causing toxic effects. The settlement-inhibitory effects of PGA were counterbalanced by higher Ca2+ conditions. Lower Ca2+ environments and the microstructural changes with hydrolytic degradation in near-surface regions of the substrata may play important roles in settlement-inhibitory effects of PGA resin.

解説
特集 船内の電力系統機器
随想
解説
解説
論文
  • 藤野 俊和, 岩本 勝美, 阿部 雅二朗, 田中 健太郎
    2017 年 52 巻 1 号 p. 92-100
    発行日: 2017/01/01
    公開日: 2018/01/16
    ジャーナル フリー

    When a manufacture error occurs, the actual size of a hydrodynamic journal bearing can differ from its basic dimension. In this case, it is considered that the characteristics of the hydrodynamic journal bearing may also be different from what has been expected, due to changes in oil film pressure distribution between the bearing and journal. The purpose of this study is to elucidate effects of manufacturing errors on the static and dynamic characteristics of multi-lobe hydrodynamic journal bearings, whose structures are relatively simple and whose oscillation stability in the rotor shaft-bearing system is relatively high. The study is also intended to come up with a proposal for guidelines about the optimized design for multi-lobe hydrodynamic journal bearings. As the first step to accomplish these purposes, this paper analyzed and examined changes in the static characteristics of a four-lobe hydrodynamic journal bearing, such as oil film pressure distribution, journal center locus, minimum oil film thickness and friction coefficient between the bearing and journal, when the position of the bottom lobe at the sliding surface is shifted from where it should be due to manufacturing errors. The results of the study show that when the position of the lobe is moved inside or outside of the bearing from the original location due to manufacturing errors, minimum oil film thickness may become smaller in comparison with the situation in which the lobe stays at the original location. The results also show that friction coefficient between the bearing and journal does not change significantly irrespective of manufacturing errors.

  • 藤野 俊和, 岩本 勝美, 阿部 雅二朗, 田中 健太郎
    2017 年 52 巻 1 号 p. 101-110
    発行日: 2017/01/01
    公開日: 2018/01/16
    ジャーナル フリー

    The purpose of this study is to elucidate effects of manufacturing errors on the static and dynamic characteristics of multi-lobe hydrodynamic journal bearings, whose structures are relatively simple and whose oscillation stability in the rotor shaft-bearing system is relatively high. The study is also intended to come up with a proposal for guidelines about the optimized design for multi-lobe hydrodynamic journal bearings. This paper analyzed and examined changes in the static characteristics of a four-lobe hydrodynamic journal bearing, such as oil film pressure distribution, journal center locus, minimum oil film thickness and friction coefficient between the bearing and journal, when the position of the side lobe at the sliding surface is shifted from where it should be due to manufacturing errors. And then, design guidelines for four-lobe hydrodynamic journal bearings were discussed based on the results of the analysis. The results of the study show that when the position of the lobe is moved inside of the bearing from the original location due to manufacturing errors, minimum oil film thickness becomes smaller in comparison with the situation in which the lobe stays at the original location. The results also show that in this case, friction coefficient between the bearing and journal becomes slightly higher when it is compared with the situation in which the side lobe is shifted inside of the bearing from the original location with higher bearing load. If arithmetic average roughness Ra of the sliding surface of the journal and lobe is below 0.2, a shift up to 0.2 times as large as machined clearance cp in the inner or outer direction of the bearing at the sliding surface near the side and bottom lobes will be tolerable.

報告
研究室紹介
シニアサロン
feedback
Top