著者
佐々木 哲也 本田 尚 山口 篤志
出版者
独立行政法人労働安全衛生総合研究所
雑誌
基盤研究(C)
巻号頁・発行日
2012-04-01

ワイヤロープの疲労破壊はこれまで表面素線が先行すると考えられていたが、IWRCロープでは、内部の素線が先行する場合のあることが明らかになっている。そこで、本研究では各種IWRCロープについてS字曲げ疲労試験を行うとともに、ワイヤロープ素線のフレッティング疲労試験を行った。その結果、フィラー形とウォリントンシール型ではどちらも内部の損傷が先行するが、その損傷形態には大きな違いがあることが明らかになった。またフレッティング疲労には、素線に作用する繰返し引張荷重の大きさよりも素線同士の圧縮力の方が大きな影響を及ぼすことが明らかになった。
著者
森下 皓文 森尾 学 山口 篤季 十河 泰弘
出版者
一般社団法人 人工知能学会
雑誌
人工知能学会全国大会論文集 第37回 (2023) (ISSN:27587347)
巻号頁・発行日
pp.2E5GS605, 2023 (Released:2023-07-10)

言語モデルは高い言語理解能力を持つ一方で,論理的な推論は苦手であることが分かってきている.この課題に対して近年,自動で生成した大量の演繹推論事例(演繹コーパス)の学習によって演繹推論能力を強化するアプローチが提案されており,一定の効果が確認されている.一方で,演繹コーパスでの学習が演繹推論能力のどのような側面の強化に寄与しているかについては,未だ明らかでない.「側面」とは例えば,多様な演繹規則の習得・ステップ数の多い演繹の実行,等である.この調査は演繹推論能力向上に向けた今後の方向性を定める上で不可欠である. そこで本研究は,この調査を行う.各側面を切り分けて分析するため,特定の側面のみを強調した調査用のアブレーション・コーパスを(全ての側面について)生成し,そのコーパスでの学習が言語モデルの演繹推論能力を向上させるかどうかを確認する.更に,これら調査結果を基に,各側面強化のための今後の方向性を議論する.最後に,後続研究のためコーパス・ソースコード・学習済みモデルを公開する.
著者
小林 淳希 宮下 洋平 大洞 裕貴 織田 さやか 田中 邦明 松野 孝平 山口 篤 今井 一郎
出版者
Faculty of Fisheries Sciences, Hokkaido University
雑誌
Memoirs of the Faculty of Fisheries Sciences, Hokkaido University (ISSN:24353361)
巻号頁・発行日
vol.60, pp.33-67, 2021-12

Onuma and Konuma are belonging to the Onuma Quasi-National Park and are located in southern Hokkaido. The fisheries and tourism are important industries in this lake area. Eutrophication has progressed in these lakes since the 1980s, and nuisance blooms of cyanobacteria have occurred every summer to autumn. The outbreaks of cyanobacterial blooms substantially destroy the ecosystem due to the production of cyanobacterial toxins, and effective countermeasures are urgently needed. However, in the lakes of Oshima Onuma, there is a paucity of knowledge about the appearance trends of phytoplankton including cyanobacteria. Therefore, seasonal monitorings were carried out on the phytoplankton community in the water column and the relatioships were discussed between dynamics of phytoplankton communities and changes in environmental factors in the lakes of Oshima Onuma. The survey was conducted once a month as a rule at Stns. 1-5 (Stn. 1 is the northeastern end of Onuma, only Stn. 5 is in Konuma) and at Stn. OP and Stn. OC along the shore of the Lake Onuma during the period of May-November 2015 and April- October 2016. The parameters of hydraulic environments were measured about water temperature, pH, transparency, dissolved oxygen, nutrient concentrations (NO3-N, NO2-N, NH4-N, PO4-P, SiO2-Si), chlorophyll a concentration, and pheophytin. The chlorophyll a concentration of the surface water showed a single-peak type fluctuation with the maximum value (28.7 μg L-1 at Stn. 2) in August at all stations in 2015. In 2016, the largest single-peak type fluctuation was observed in September- October with the exception of Stn. 3. Concerning the seasonal variation of the phytoplankton species, the proportion of Uroglena volvox (Chrysophyceae) was high at Stn. 5 in May, but the pennate diatoms Fragilaria crotonensis and Asterionella formosa, and the centric diatoms Aulacoseira spp. at other stations other than Stn. 5. As for cyanobacteria in August 2015, Dolichospermum planctonicum, possessing an ability of nitrogen-fixation, dominated (maximum 4.4×104 cells mL-1) at all the stations under the severe nitrogen-deficient conditions (N/P < 16). In the following year 2016, the cell densities of Dolichospermum spp. were low, and Microcystis spp. dominated at all the stations (up to 5.6×104 cells mL-1) with the enough nitrogen conditions. It is hence thought that the N / P ratio determined the dominant species of cyanobacteria in the summer season. In September and thereafter, the number of phytoplankton cells decreased on the whole in both years, and the centric diatoms Aulacoseira spp., Cyclotella spp. and the cryptophyte Cryptmonas spp. tended to increase. Considering the occurrence mechanisms of cyanobacterial blooms based on the fluctuation trends of cyanobacteria in the water columns, it is found that the supply of Microcystis aeruginosa from the lake bottom sediment to the water column (water temperature of 10-15ºC is required) is progressing at all stations in April-June. Since Onuma and Konuma are shallow with an average depth of 4.7 m, wind-inducing resuspension of bottom sediments probably contribute to the supply of cyanobacteria to water columns. In addition, since cyanobacterial cells tend to float and accumulate in surface water, it is needed to take physical factors such as wind and flow into consideration regarding the distribution of the blooms of cyanobacteria.
著者
大塚 攻 山口 篤 花村 幸生
出版者
日本プランクトン学会
雑誌
日本プランクトン学会報 (ISSN:03878961)
巻号頁・発行日
vol.58, no.1, pp.87-93, 2011-02-26

本稿では,動物プランク卜ンとして重要なカイアシ類,アミ類に共生する繊毛虫の生活史,生態,生態的機能について概説する。なお,「共生」に関する厳密な定義は困難である場合があるが(Bush et al. 2001), ここでは相利共生,片利共生,寄生,捕食寄生,便乗なども含む広義の意味で「共生」という言葉を使用し,宿主と共生生物との種間関係が明確でない場合も「共生」という言葉を使用する。通常,宿主が共生生物より体サイズが大きく,宿主と共生生物間に食関係か成立していて宿主になんらかの悪影響がある場合を「寄生」,宿主を確実に死に至らしめる場合を「捕食寄生」と呼ぶこととする。
著者
山口 篤
出版者
Faculty of Fisheries Sciences, Hokkaido University
雑誌
Memoirs of the Faculty of Fisheries Sciences, Hokkaido University (ISSN:21861927)
巻号頁・発行日
vol.53, no.2, pp.13-18, 2011-06

Recent advances in studies on zooplankton ecology in the Oyashio region were reviewed. In this review, the following three topics were argued : i) ecosystem structure in the region, ii) inter-annual changes in zooplankton biomass and iii) optical analysis on zooplankton samples. Annual mean biomass in the Oyashio region was estimated to be 23 g C m-2 and was dominated by mesozooplankton (34%), followed by phytoplankton (28%), heterotrophic bacteria (15%) and microzooplankton (14%). Within the mesozooplankton, large grazing copepods (i.e. Neocalanus spp., Eucalanus bungii and Metridia spp.) were the most important taxa to govern the seasonal and inter-annual variability. Through the analysis on zooplankton samples collected during 1950’s to present, inter-annual variability in mesozooplankton biomass was revealed to be related with the Pacific Decadal Oscillation (PDO) and climate regime shift. While the zooplankton size is important to determine the food quality for pelagic fishes and the mass flux to the deep ocean, detailed analysis on their size distribution is not made for most of the samples, because of the difficult and time consuming analysis involved. The recently advanced optical plankton counter (OPC) can measure the particle (=plankton) with detailed size distribution (4096 size unit between 0.25 mm and 20 mm) within a short period, therefore the application of OPC on zooplankton samples may solve the problem in future.