Open Access Collection of International and Scholarly Papers
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2022/2023 Annual Cruise Report of the T/V Umitaka Maru Voyage : 【UM-22-04】 Cruise Report
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AIによる状況認識システム構築に向けた画像処理の効果検証
Get PDF東京海洋大学修士(工学)東京海洋大学修士学位論文 2023年度(2024年3月) 海洋システム工学 修士 第4338号指導教員: 清水悦郎全文公表年月日: 2024-05-28master thesi
酸化カーボンナノチューブ固定化ろ紙電極を用いた新規コルチゾールバイオセンサの開発
Get PDF東京海洋大学修士(工学)東京海洋大学修士学位論文 2023年度(2024年3月) 海洋システム工学 修士 第4355号指導教員: 大貫等全文公表年月日: 2024-05-28master thesi
遼東湾沖オイルプラットフォームからの重油流出による環境リスク評価
Get PDF東京海洋大学修士(海洋科学)東京海洋大学修士学位論文 2024年度(2024年9月) 海洋資源環境学 修士 第4399号指導教員: 長井健容全文公表年月日: 2024-02-12master thesi
海洋無脊椎動物におけるマイクロプラスチック汚染に関する研究: 東京湾とケニア沿岸との比較
Get PDF東京海洋大学博士(海洋科学)東京海洋大学博士学位論文 2024年度(2024年9月) 応用環境システム学 課程博士 甲第708号指導教員: 荒川久幸全文公表年月日: 2025-02-12doctoral thesi
A Study on the Prediction of LNG Ship Spot Freight Rates using Artificial Intelligence
No full textNatural gas is considered an environmentally friendly energy source, and its demand is continuously increasing. Consequently, the volatility of freight rates for Liquefied Natural Gas (LNG) carriers is also rising. Given this high volatility, there is a need for research to predict freight rates in advance, aiding the decision-making processes of shipping companies. While numerous studies have focused on freight rate prediction for various types of ships, research specifically targeting LNG carriers remains limited. This study exclusively utilizes freight data from 160K LNG carriers and employs the Long Short-Term Memory (LSTM) model, enhanced through hyperparameter tuning, to predict spot freight rates. Additionally, the study compares the predictive performance of the LSTM model with that of the Auto-Regressive Integrated Moving Average (ARIMA) and SARIMA models, which are well-established in time series analysis. The prediction experiments reveal that the LSTM-based model, in terms of Mean Absolute Percentage Error (MAPE) and Root Mean Square Error (RMSE), outperforms the others, offering the most accurate freight rate predictions. However, the hyperparameter-tuned model shows proficiency in predicting sudden increases in freight rates. This study suggests that using time series data alone can enhance the objectivity of freight rate predictions. Future research involving comparative analyses and experiments across various predictive models in high-performance computing environments is expected to improve prediction performance further. Such advancements would be valuable for forecasting shipping market conditions more effectively.公開日: 2024-07-0123K2101521H01564journal articl
Development of Seafarers’ Performance Evaluation Method Based on Eye-tracking Data
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Nitrogen isotope homogenization of dissolved ammonium with depth and 15N enrichment of ammonium during incorporation into expandable layer silicates in organic-rich marine sediment from Guaymas Basin, Gulf of California
No full textSedimentary nitrogen isotopic ratios are used as a proxy for ancient biogeochemical cycles on Earth's surface. It is generally accepted that sediment hole tops record primary signatures because organic nitrogen (ON) is predominant in this part of the hole. In contrast to such early to middle diagenetic stages, it is well known that heavier nitrogen isotope 15N tends to enrich in sedimentary rocks during later diagenetic and metamorphic stages. However, there are some critical gaps in our understanding of nitrogen isotopic alteration associated with abiotic processes during early-middle diagenesis. In this study, we examined the isotope ratios of ammonium nitrogen in interstitial water (IW) and total nitrogen (TN), including exchangeable ammonium and mineral nitrogen, in the solid-phase of organic-rich-sediment recovered by International Ocean Discovery Program (IODP) Expedition 385 cores drilled in the Guaymas Basin, Gulf of California, that contained ammonium-rich IW. The isotopic ratios (δ15N value) of TN are the most variable with depth compared to any other type of nitrogen. This variation can be interpreted as reflecting changes in the water mass environment in the basin caused by glacial–interglacial climate changes, modifying the δ15N values of the marine primary producers. Thus, the δ15N value of TN is a proxy for environmental change in the basin, while each component of TN shows different trends. The δ15N values of IW and exchangeable ammonium did not exhibit significant changes with depth, but the latter values are about 3 ‰ enriched in 15N. This may be due to advective transport of solute into adjacent layers followed by the formation of an isotopic equilibrium between IW and exchangeable ammonium in the case of fast sediment accumulation rate. The δ15N value of exchangeable ammonium is the highest among the other types of nitrogen with one exception, where the δ15N value of TN is the highest. The calculated δ15N values of ON based on mass balance are almost the same as those of associated TN in the shallow sediment layers (< 150 m below seafloor), but the difference in the δ15N values of TN and ON are significant in the deeper layers, where proportions of ON contents are <50%. In particular, in the layer where the δ15N value of TN is the highest, that of ON shows an even higher value and the difference reaches 3.5 ‰. The δ15N values of mineral nitrogen are similar to that of IW ammonium except the surface layers. Under such conditions, when δ15N value of TN is intermediate between those of mineral nitrogen and exchangeable ammonium, calculated δ15N value of ON is close to that of TN. On the other hand, if δ15N value of TN is out of the range between mineral nitrogen and exchangeable ammonium, it causes further difference in δ15N value of ON. It means that the fluctuation of δ15N values of TN is reduced relative to those of ON through depth. It has been considered that δ15N value of TN in sediment is similar to that of ON, and changes in the δ15N value of TN due to diagenesis are limited, but in such environment ON fluctuations over depth may be slightly underestimated.公開日: 2024-10-1918K0375621H0159021H01172journal articl
ケルセチン豊富なタマネギエキスがパンガシウスPangasius hypophthalmusすり身のゲル形成能に及ぼす影響
Get PDF東京海洋大学博士(海洋科学)東京海洋大学博士学位論文 2024年度(2024年9月) 応用生命科学 課程博士 甲第703号指導教員: 大迫一史doctoral thesi
アイゴ Siganus fuscescensの網羅的ゲノム研究：ミトゲノム、全ゲノム、および腸内メタゲノム解析
Get PDF東京海洋大学博士(海洋科学)東京海洋大学博士学位論文 2024年度(2024年9月) 応用生命科学 課程博士 甲第704号指導教員: 近藤秀裕doctoral thesi