{"created":"2022-01-27T02:46:19.884399+00:00","id":2003031,"links":{},"metadata":{"_buckets":{"deposit":"61c2fe92-95c1-4ea9-8dc7-f41aebabeb0e"},"_deposit":{"id":"2003031","owners":[1],"pid":{"revision_id":0,"type":"depid","value":"2003031"},"status":"published"},"_oai":{"id":"oai:u-ryukyu.repo.nii.ac.jp:02003031","sets":["1642837622505:1642837905044:1642837913657","1642838403551:1642838407312"]},"author_link":[],"item_1617186331708":{"attribute_name":"Title","attribute_value_mlt":[{"subitem_1551255647225":"苗マットの弾塑性学的研究(農業工学科)","subitem_1551255648112":"ja"},{"subitem_1551255647225":"Elasto-plastic Studies on Rice Seedling Mat (Department of Agricultural Engineering)","subitem_1551255648112":"en"}]},"item_1617186419668":{"attribute_name":"Creator","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"上野, 正実","creatorNameLang":"ja"}]},{"creatorNames":[{"creatorName":"Ueno, Masami","creatorNameLang":"en"}]}]},"item_1617186476635":{"attribute_name":"Access Rights","attribute_value_mlt":[{"subitem_1522299639480":"open access","subitem_1600958577026":"http://purl.org/coar/access_right/c_abf2"}]},"item_1617186626617":{"attribute_name":"Description","attribute_value_mlt":[{"subitem_description":"我国独自の技術で開発された土付苗用田植機は1967年の市販開始後, 急速に普及し, 現在では普及台数約189万台, 水稲全作付け面積の90%およそ220万haの植付け作業に使用されている。土付苗用田植機は今後とも田植機の主流であると考えられるが, 機械の性能はすでに一定水準に達しており, 現在ではさらに進んだ高性能化を活発に進める段階に入っている。土付苗用田植機において作業能率および植付け精度に関する高性能化を図るためには, 多条化に加えて, 苗補給の円滑化が必要である。これにはその基礎資料となる苗マットの力学的性質を明らかにしておかねばならない。また, 機械移植に適した力学的性質を持つ苗マットの確保が重要である。一方, 土付苗用田植機の普及によって年間約200万ton(推定)以上の大量の苗マットが使用されており, これに伴って苗マット用床土の消費量は急激に増加し, 近年では「人工床土」と称する床土も流通している。中には粘着力や付着力が強すぎたり逆に弱すぎて, 移植作業に支障をきたす床土も見受けられる。このような床土の質の多様化および量の増加が苗マットの物理的性質にいかなる影響を与えるかを機械移植の観点から明確にする必要がある。ところで, 苗マットは床土中に互いに絡み合った根群が混在した構造を持ち, 一種の複合材料と見なしうる。すなわち, 母材である床土の力学的性質が根によって強化された材料である。従来からの数多くの研究にもかかわらず, 未解決の問題が少なくない土の力学的性質に比べて, 苗マットのそれは根の影響があるために土よりさらに複雑である。苗マットの物理性に関連する従来の研究は少なく, 特に変形性および強度に関する基本的な力学的分析はほとんど行われていなかった。そこで, 本研究では苗マットの力学的性質をまず実験的に解明し, 次に, その結果を整理して弾塑性学的な観点より分析を試み, 最終的に具体的な弾塑性構成式を導いた。第II章では, 実験結果より苗マットのたわみ特性, 分離特性, 引張特性, 圧縮特性およびせん断特性について検討を行い, 各々の特性だけでなくこれらの相互関係を明らかにした。これらの試験に供試した苗マットは育苗条件や床土などを多様に変えて育苗したので, 以下に述べる諸特性値は実際に使用されている稚苗苗マットの力学的性質を十分に表現するものと考える。さらに苗マットの力学的性質に対する土と根の影響を分析した。","subitem_description_type":"Other"},{"subitem_description":"たわみ試験では苗マットを短辺に平行な線上において160mmスパンで両辺支持し, 自重および集中荷重の段階的な載荷によるたわみ量の変化を測定した。たわみの経時変化は非常に小さく, 実用上は無視しても差し支えないことがわかった。2.0kgf載荷時の中央部のたわみ量は8&acd;23mmで, 一旦除荷すると回復変形量は1&acd;6mmしかなく, 苗マットのたわみは塑性変形が顕著であることを明らかにした。荷重-たわみ曲線は勾配が漸増する形状で, 除荷・再負荷過程におけるそれは顕著なヒステリシス・ループを描いた後に単純載荷過程における曲線に収束した。5.0kgf程度の集中荷重では大半の苗マットは破壊しなかった。苗マットのたわみ特性に関しては床土の種類, 播種量などが主要な因子であり, また根の分布状態を表わす測度の1つとして根重を考えると, 根重が大きい苗マットほどたわみに対する抵抗は大きくなる傾向が見られた。土付苗用田植機の国営検査において苗条件を調査する方法として定められている 5・6本苗の分離試験法では苗マットの力学的性質を適切に測定しえないことが判明した。そこで広い断面で苗マットを分離する方法を用いたところ, 精度の良いデータが得られたので, これを苗マットの改良分離試験法として提案した。新しい試験法によって得られた分離力-変位曲線より分離抵抗などのいくつかの特性値を導入して分離特性の分析を行った。分離抵抗すなわち破断抵抗は0.10&acd;0.14kgf/(cm)^2であった。分離特性は播種量, 根重, 含水比あるいは床土の種類などに大きな影響を受けることを明らかにした。引張試験は苗マット試験片の支持方式などに問題が多く, 試験法を確立するまでには多くの検討を要した。最終的に70×280mmの矩形試験片を水平に置き, 両端を各々2枚の板ではさんで支持する試験装置を用いた。引張における応力-ひずみ曲線はおおまかにσ=a√<ε>(σ : 応力(kgf/(cm)^2), ε : ひずみ)で近似しえた。係数aの値は0.1&acd;0.4kgf/(cm)^2であった。最大引張応力すなわち引張強度は0.02& acd;0.17kgf/(cm)^2,この時のひずみ量は0.03&acd;0.32であった。応力-ひずみ曲線の初期勾配を見かけの縦弾性係数とすると0.31&acd;8.90kgf/(cm)^2であった。これらの引張特性値を比較すると互いに相関関係が見られ, 変形抵抗の大きい苗マットは大きな強度を示した。","subitem_description_type":"Other"},{"subitem_description":"Japanese-type rice transplanter have been spread so widely since 1967 putting on sale. About 1.9 million machines are used in about 2.2 million hectares paddy fields, in 1981. The performance of this machine already reached enough level. But there are two problems relating to this machine. One is to develop the automatic self-feeder of rice seedling mats for advanced performance. The other is to keep and standardize the physical properties of rice seedling mats and bed soils. Achieving this high performance or solving this problem, it may be necessary to make clear the mechanical properties of rice seedling mats. The main purpose of this paper is to make clear the mechanical properties of rice seedling mats from the following five points of view. (a) The mechanical test methods are examined and settled. (b) The strength and deformation properties to the deflection, dividing, extension, compression and shear are examined experimentally. (c) The interrelationships of those test results are investigated to grasp the mechanical properties as a whole. (d) The factors influenced to those properties are analyzed regarding as a composite material of roots and soil. (e) The elasto-plastic behaviours of rice seedling mats are discussed theoretically by assuming an elasto-plastic model like soil's one. Deflection properties of rice seedling mats was grasped by use of a creep test under the dead load and a continuous loading test under the concentrated load at the center of 160mm span. The kinds of bed soil, the planting density and the days for raising of seedling were regarded as experimental factors and were changed to several levels to vary qualities of mats provided for tests.","subitem_description_type":"Other"},{"subitem_description":"(1) The two types of deflection test, one of them was simply supported at the opposite ends of a mat with the dead load, and the other was fixed at the opposite ends of a mat with the concentrated load at the center, were treated as easy methods to estimate the mechanical strength of rice seedling mats by the comparison with the deflection at the center of span. It seemed that the latter test gave an accurate estimation to the mechanical strength. (2) The deflection of mats had little change in the measuring duration (with in three minutes) either above-mentioned method. (3) The deflection of mats was remakably plastic. (4) The deflection of mats was influenced by the conditions for raising of seedling, i. e. the kinds of bed soil, the planting density, the days for raising of seedling, the weight of roots, the water content of mat and so on. In the present National Test for Agricultural Machinery related to the Japanese-type rice transplanter, only one estimation to the mechanical strength of mats is treated by the measurement of dividing resistance to five or six rice seedlings from a mat. It was viewed that this test was the most suitable method and how to represent the dividing properties of mats. (5) At first, the dividing test according to the method by pulling five or six seedlings apart from their own mat was done. The experimental results showed that this test didn't give an accurate dividing resistance of mat, with about thirty times repetations of measurement, because the confidence interval of data with confidence coefficient 95% was so large. (6) After many methods and devices on the dividing test were examined, one method that a mat was divided into two parts at the parallel cross section to short edges of mat was chosen in this study. In spite of a few rcpetations of measurement (only four times) to a mat, the confidence interval for the dividing resistance with confidence coefficient 95% became smaller than that of abovementioned test. So, this test might be able to estimate more accurately the dividing resistance. (7) The four characteristic values to represent the dividing curves (load-displacement relationship), namely the dividing resistance, the dividing secant modulus, the initial secant modulus and the half-value width, were available to","subitem_description_type":"Other"},{"subitem_description":"紀要論文","subitem_description_type":"Other"}]},"item_1617186643794":{"attribute_name":"Publisher","attribute_value_mlt":[{"subitem_1522300295150":"ja","subitem_1522300316516":"琉球大学農学部"}]},"item_1617186702042":{"attribute_name":"Language","attribute_value_mlt":[{"subitem_1551255818386":"jpn"}]},"item_1617186783814":{"attribute_name":"Identifier","attribute_value_mlt":[{"subitem_identifier_type":"HDL","subitem_identifier_uri":"http://hdl.handle.net/20.500.12000/4002"}]},"item_1617186920753":{"attribute_name":"Source Identifier","attribute_value_mlt":[{"subitem_1522646500366":"ISSN","subitem_1522646572813":"0370-4246"},{"subitem_1522646500366":"NCID","subitem_1522646572813":"AN00250548"}]},"item_1617186941041":{"attribute_name":"Source Title","attribute_value_mlt":[{"subitem_1522650068558":"ja","subitem_1522650091861":"琉球大学農学部学術報告"},{"subitem_1522650068558":"en","subitem_1522650091861":"The Science Bulletin of the Faculty of Agriculture. University of the Ryukyus"}]},"item_1617187056579":{"attribute_name":"Bibliographic Information","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"1983-11-19","bibliographicIssueDateType":"Issued"},"bibliographicIssueNumber":"30","bibliographicPageEnd":"366","bibliographicPageStart":"255"}]},"item_1617258105262":{"attribute_name":"Resource Type","attribute_value_mlt":[{"resourcetype":"departmental bulletin paper","resourceuri":"http://purl.org/coar/resource_type/c_6501"}]},"item_1617265215918":{"attribute_name":"Version Type","attribute_value_mlt":[{"subitem_1522305645492":"VoR","subitem_1600292170262":"http://purl.org/coar/version/c_970fb48d4fbd8a85"}]},"item_1617605131499":{"attribute_name":"File","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_access","filename":"KJ00000162176.pdf","mimetype":"application/pdf","url":{"objectType":"fulltext","url":"https://u-ryukyu.repo.nii.ac.jp/record/2003031/files/KJ00000162176.pdf"},"version_id":"8ef08fce-56c4-462a-a1f8-1e12b1e34986"}]},"item_title":"苗マットの弾塑性学的研究(農業工学科)","item_type_id":"15","owner":"1","path":["1642837913657","1642838407312"],"pubdate":{"attribute_name":"PubDate","attribute_value":"2008-02-14"},"publish_date":"2008-02-14","publish_status":"0","recid":"2003031","relation_version_is_last":true,"title":["苗マットの弾塑性学的研究(農業工学科)"],"weko_creator_id":"1","weko_shared_id":-1},"updated":"2022-10-31T01:14:00.543228+00:00"}