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Wyszukujesz frazę "Hirayama, K." wg kryterium: Autor


Wyświetlanie 1-3 z 3
Tytuł:
Ship Collision Avoidance by Distributed Tabu Search
Autorzy:
Kim, D.
Hirayama, K.
Okimoto, M.
Powiązania:
https://bibliotekanauki.pl/articles/116919.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
Safety of Navigation
Collision Avoidance
Distributed Tabu Search Algorithm (DTSA)
Distributed Local Search Algorithm (DLSA)
Quasi-Local Minimum (QLM)
Tabu Search Algorithm
Local Search Algorithm
Distributed Tabu Search
Opis:
More than 90% of world trade is transported by sea. The size and speed of ships is rapidly increasing in order to boost economic efficiency. If ships collide, the damage and cost can be astronomical. It is very difficult for officers to ascertain routes that will avoid collisions, especially when multiple ships travel the same waters. There are several ways to prevent ship collisions, such as lookouts, radar, and VHF radio. More advanced methodologies, such as ship domain, fuzzy theory, and genetic algorithm, have been proposed. These methods work well in one-on-one situations, but are more difficult to apply in multiple-ship situations. Therefore, we proposed the Distributed Local Search Algorithm (DLSA) to avoid ship collisions as a precedent study. DLSA is a distributed algorithm in which multiple ships communicate with each other within a certain area. DLSA computes collision risk based on the information received from neighboring ships. However, DLSA suffers from Quasi-Local Minimum (QLM), which prevents a ship from changing course even when a collision risk arises. In our study, we developed the Distributed Tabu Search Algorithm (DTSA). DTSA uses a tabu list to escape from QLM that also exploits a modified cost function and enlarged domain of next-intended courses to increase its efficiency. We conducted experiments to compare the performance of DLSA and DTSA. The results showed that DTSA outperformed DLSA.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2015, 9, 1; 23-29
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
DSSA+: distributed collision avoidance algorithm in an environment where both course and speed changes are allowed
Autorzy:
Hirayama, K.
Miyake, K.
Shiotani, T.
Okimoto, T.
Powiązania:
https://bibliotekanauki.pl/articles/116483.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
collision avoidance
collision avoidance algorithm
vessel course changes
vessel speed changes
Distributed Stochastic Search Algorithm (DSSA)
colregs
ARPA
Distributed Constraint Optimization Problem (DCOP)
Opis:
Distributed Stochastic Search Algorithm (DSSA) is one of state-of-the-art distributed algorithms for the ship collision avoidance problem. In DSSA, whenever a ship encounters with any number of other ships (neighboring ships), she will select her course with a minimum cost after coordinating their decisions with her neighboring ships. The original DSSA assumes that ships can change only their courses while keeping their speed considering kinematic properties of ships in general. However, considering future possibilities to address more complex situations that may cause ship collision or to deal with collision of other vehicles (such as mobile robots or drones), the options of speed changes are necessary for DSSA to make itself more flexible and extensive. In this paper, we present DSSA+, as a generalization of DSSA, in which speed change are naturally incorporated as decision variables in the original DSSA. Experimental evaluations are provided to show how powerful this generalization is.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2019, 13, 1; 117-123
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Activation of Retrotransposon in Red Alga by Underwater Pulsed Discharge
Autorzy:
Hirayama, K.
Wang, D.
Matsuda, M.
Lin, X.
Namihira, T.
Takano, H.
Takio, S.
Akiyama, H.
Powiązania:
https://bibliotekanauki.pl/articles/1807936.pdf
Data publikacji:
2009-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.80.Wq
Opis:
Retrotransposons are mobile genetic elements that accomplish transposition via an RNA intermediate. These elements can be transcriptionally activated by stress factors, such as UV light, ozone, pathogens, wounding and drought. A red alga, Porphyra yezoensis has recently been recognized as a model plant for fundamental and applied study in marine biological science. In this paper, pulsed streamer-like discharge in liquid was used as a new stress condition, and the transcriptional levels of retrotransposon and functional genes of a red alga, Porphyra yezoensis was investigated. From the results of reverse transcription-polymerase chain reaction (RT-PCR) experiments, it is clear that the transcriptions of retrotransposon and functional genes were activated by applying pulsed streamer-like discharge.
Źródło:
Acta Physica Polonica A; 2009, 115, 6; 1110-1111
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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