日本財団 図書館

共通ヘッダを読みとばす


Top > 産業 > 運輸.交通 > 成果物情報

Conference Proceedings Vol. I, II, III

 事業名 海事シミュレーションと船舶操縦に関する国際会議の開催
 団体名 日本船舶海洋工学会 注目度注目度5


5. FAULT TREE ANALYSIS ABOUT UNSAFE NAVIGATION IN EXTRAORDINARY SITUATION
 We utilized Fault Tree Analysis to consider the rationality about the agreement between achievement level of functions before the trouble and 3 behaviour patterns after the trouble.
 
5.1 Construct the Fault Tree
 
 Shown as Fig. 5, we constructed the Fault Tree about the extraordinary situation in Fig. 4.
 The top phenomenon is "unsafe navigation in extraordinary situation". Under this phenomenon, 3 kinds of phenomena follow with OR gate. If one, of these phenomena happened, the situation would grow up to "unsafe navigation in extraordinary situation".
 "Insufficient Extraordinary Reaction" under the top phenomenon would come,, if "Occurrence of trouble" and "Insufficient time for reaction" came at the same time. On this Fault Tree, there is plural "Occurrence of trouble" at different places. Other phenomena are the same. Thus Fault Tree can be constructed.
 "Insufficient Positioning" under the top phenomenon would come, if both "Insufficient Positioning after trouble" and "Insufficient Positioning before trouble" happened. Then again, "Insufficient Positioning after trouble" would come, if either "No Positioning after trouble" or "Positioning after trouble is impossible" happened. Still more, "Positioning after trouble is impossible" would come if both "No time for Positioning because of Extraordinary Reaction" and "No time / No speed reduction" happened.
 "Insufficient recognition on other ships" under the top phenomenon can be constructed m the same way as "Insufficient Positioning". Under this phenomena, phenomena concerned Lookout follows.
 
Fig.5 Fault Tree about unsafe navigation in extraordinary situation
 
5.2 Analysis on the Fault Tree
 
 We analyzed unsafe navigation in extraordinary situation based on the Fault Tree.
 
5.2.1 Fundamental phenomenon
 
 This Fault Tree has 8 fundamental phenomena. These are bottom phenomena on this tree. These fundamental phenomena are defined as following from x1 to x8.
 
x1: Occurrence of trouble
x2: Insufficient time for reaction
x3: Insufficient Positioning before trouble
x4: No Positioning after trouble
x5: No time / No speed reduction
x6: Insufficient Lookout before trouble
x7: No Lookout after trouble
x8: Insufficient recognition because of no Communication
 
5.2.2 Minimal Cut Set and Structure Function
 
 Minimal cut set is the set of fundamental phenomenon, which is necessary and sufficient for occurrence of top phenomenon.
 The minimal cut sets of this Fault Tree are 5 kinds as following.
 
1) {x6, x7}
2) {x3, x4}
3) {x1, x2}
4) {x1, x6, x8}
5) {x1, x3, x5}
 
 From these minimal cut set, we could obtain the structure function, Ö(x) formula, to calculate the fault tree structure importance.
 
Ö(x) = 1 - {1-x6*x7} {1-x3*x4} {1-x1*x2} {1-x1*x6*x8} {1-x1*x3*x5} (1)
 
 We can obtain each fault tree importance of these fundamental phenomena using formula (1).
 
5.2.3 Occurrence Rate of Top Phenomenon
 
 If we defined each occurrence rate of phenomena as following, we could obtain the g function, g formula, to calculate the occurrence rate of top phenomenon.
 
q1: occurrence rate of x1
q2: occurrence rate of x2
q3: occurrence rate of x3
q4: occurrence rate of x4
q5: occurrence rate of x5
q6: occurrence rate of x6
q7: occurrence rate of x7
q8: occurrence rate of x8
 
g = 1-{1-q6*q7} {1-q3*q4} {1-q1*q2} {1-q1*q6*q8}{1-q1*q3*q5} (2)
 
 Therefore, if we could obtain the concrete value for these, rates, we can calculate the occurrence rate of top phenomenon.
 
5.2.4 Fault Tree Structure Importance
 
 The Fault Tree structure importance indicates how much each phenomenon influences on the top phenomenon. This Fault Tree has 8 fundamental phenomena. Table 2 shows the results for each fundamental phenomenon.
 
Table 2 Fault Tree Structure Importance about each fundamental phenomenon
  Fundamental Phenomenon value
1 Occurrence of trouble 0.367
2 Insufficient time for reaction 0.195
3 Insufficient Positioning before trouble 0.304
4 No Positioning after trouble 0.226
5 No time / No speed reduction 0.039
6 Insufficient Lookout before trouble 0.304
7 No Lookout after trouble 0.226
8 Insufficient recognition because of no Communication 0.039
 
 The higher the value of Fault Tree structure importance is, the more the fundamental phenomenon influences on the top phenomenon occur.
 
 Shown as table 2, there is a large difference between 8 fundamental phenomena from 0.039 to 0.367.
 
 The highest importance is "occurrence of trouble", it is a matter of course.
 
 The following high importance, O.304, was indicated at two phenomena, "Insufficient Positioning before trouble" and "Insufficient Lookout before trouble". These are the highest importance except "occurrence of trouble". It means that these phenomena influence on "Unsafe navigation in extraordinary situation" largely. There calculation results of Fault Tree structure importance shows that Positioning before trouble and Lookout before trouble are important. Positioning and Lookout should be always kept doing in ordinary situation. A decline of these functions causes unsafe navigation in extraordinary situation.
 Therefore this result can become a reason for the agreement between achievement level of Positioning and Lookout functions before the trouble and 3 behaviour patterns after the trouble.
 
 "No Positioning after trouble" and "No lookout after trouble" follow with 0.226. In consideration of the importance of "Insufficient Positioning before trouble" and "Insufficient Lookout before trouble", the influence of both Positioning and Lookout after trouble does not change. But then again, it is thought that this is no more than adding fuel for the acceleration up to more unsuitable situation, because of the phenomenon after trouble. It is also thought that both "Insufficient Positioning before trouble" and "Insufficient Lookout before trouble" cause unsuitable situation after trouble.
 
 phenomena concerned with Positioning and Lookout.
 Compared with above-mentioned phenomena, "No time by speed reduction" and "Insufficient recognition because of no communication" brings nothing but a little influence.
 
5.3 A Sign of Fault Tree Structure Importance on Behaviour
 
 We considered these influences of fundamental phenomena on 6 cases of simulator experiments.
 Fig.6 shows the comparison about frequency in use of 6 categories among 3 behaviour patterns. Case A is from behaviour pattern 1, case C is from behaviour pattern 2, case E is from behaviour pattern 3.
 
Fig. 6 Comparison about frequency in use of 6 categories among 3 behaviour patterns







サイトに関するご意見・ご質問・お問合せ   サイトマップ   個人情報保護

日本財団会長笹川陽平ブログはこちら



ランキング
注目度とは?
成果物アクセスランキング
123位
(31,818成果物中)

成果物アクセス数
105,648

集計期間:成果物公開〜現在
更新日: 2020年3月21日

関連する他の成果物

1.MARSIM'03 開催報告
2.本会議及びワークショップ開催状況写真
3.九州における離島住民からみた交通バリアフリー化に関する調査研究?鹿児島県をモデルケースとして? 報告書
  [ 同じカテゴリの成果物 ]


アンケートにご協力
御願いします

この成果物は
お役に立ちましたか?


とても役に立った
まあまあ
普通
いまいち
全く役に立たなかった


この成果物をどのような
目的でご覧になりましたか?


レポート等の作成の
参考資料として
研究の一助として
関係者として参照した
興味があったので
間違って辿り着いただけ


ご意見・ご感想

ここで入力されたご質問・資料請求には、ご回答できません。






その他・お問い合わせ
ご質問は こちら から