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一种新颖的多实例学习算法与应用
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作者 侯勇 陈章宝 张傲林 《蚌埠学院学报》 2021年第2期44-51,共8页
多实例学习(MIL)作为一种半监督学习形式,其中训练数据标签上只有不完整的知识。具体而言,标签被分配在这些包上,包中实例的标签未知。在MIL算法中,如果包中至少有一个实例为正,则包被标记为正;如果包中的所有实例均为负,则包标记为负。... 多实例学习(MIL)作为一种半监督学习形式,其中训练数据标签上只有不完整的知识。具体而言,标签被分配在这些包上,包中实例的标签未知。在MIL算法中,如果包中至少有一个实例为正,则包被标记为正;如果包中的所有实例均为负,则包标记为负。MIL算法的目标是通过学习一个分类函数,预测测试数据中包或实例的标签。同时,MIL的性质使其可应用于多种应用,从药品活动预测到文本或多媒体信息检索。对多样化密度算法的缺陷进行了改进,提出了一种新颖的多实例学习算法。最后,在图像分类/检索问题数据集-Corel数据库上,将提出的算法与其他算法,进行了性能对比评估。 展开更多
关键词 图像检索 多实例学习算法 多样化密度 密度 Corel图像库
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Mesocosm Hatcheries Using Semi-intensive Methodologies and Species Diversification in Aquaculture
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作者 Carlos Andrade Natacha Nogueira +2 位作者 Paula Silva Maria Teresa Dinis Luis Narciso 《Journal of Agricultural Science and Technology(B)》 2012年第4期428-437,共10页
Mesocosm hatcheries using semi-intensive culture methodologies are characterized by large tanks (40 m3) for fish larvae production at low densities (2-8 larvae/L), with live prey production within the tank supplem... Mesocosm hatcheries using semi-intensive culture methodologies are characterized by large tanks (40 m3) for fish larvae production at low densities (2-8 larvae/L), with live prey production within the tank supplemented by exogenous sources of feed. Due to the high biological quality of larvae produced and low level of technological input, these methodologies are regarded as an interesting option to meet the increasing fry demand from the aquaculture industry. This study aimed to describe the experience at Centro de Maricultura da Calheta, Madeira Island, Portugal, with the establishment of a mesocosm hatchery for the production of marine fish larvae. Production trials were initiated with gilthead seabream Sparus aurata. This larval species presented faster growth in total body length (TL) per day (TL = 3.7516e~ ~293day, R2 = 0.9404), higher survival rate (SR = 31.9%) and comparable swimbladder inflation rates (SB = 90%) to those of larvae reared with intensive methodologies. High larval performance was obtained with two candidate species for aquaculture: the red porgy Pagruspagrus (TL = 3.212e~~39day, R2 = 0.995; SR = 15.3%; SB = 95.7%) and the white seabream Diplodus sargus (TL = 3.6355e~~413day, R2= 0.9824; SR = 25%; SB --- 100%). Testing ofa 110 m3 mesocosm rearing tank with white seabream larvae revealed limitations associated to larger tanks namely, the amount and quality of live feed required daily. First trials with striped jack (Pseudocararoc dentex) larvae resulted in low larval survival (0.04%), but the use of a white tank avoided culture management constraints related to positive phototropism. The present results suggest that a mesocosm using semi-intensive methodologies may contribute to species diversification and consequently, to the sustainable development of aquaculture. 展开更多
关键词 Mesocosm hatchery fish larvae performance Sparus aurata Pagrus pagrus Diplodus sargus Pseudocarartx dentex.
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问题驱动式学习的实施策略初探——以“制作密度秤”教学为例
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作者 张莉芳 《物理教学》 北大核心 2022年第10期37-40,32,共5页
本文以2021年四川省遂宁市中考物理试卷第20题为例,以问题驱动为指引,探讨改装密度秤的多样化应用策略,进而培养科学思维,从而为提升学科核心素养作出应有的贡献。
关键词 问题驱动 密度多样化 问题评价
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