Results 111 to 120 of about 12,988 (195)
How much biotic nativeness matters across human demographic groups
Conservation Biology, EarlyView.Abstract Many central concepts of conservation biology—such as nativeness—are structured by ecological and social factors. However, the social consequences of using these concepts to make conservation decisions remain inadequately understood. Some researchers argue that nativeness, rather than acting as an objective proxy for important ecological ...
Harold N. Eyster, Rachelle K. Gould
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Jixie chuandong, 2004 基于遗传算法提出了的高齿弧齿锥齿轮的优化设计。设计变量是齿顶高系数和变位系数（非零变位 ） ,约束条件为齿顶变尖、根切、刀具条件限制、强度限制等 ,目标函数为重合度最大。本文编制的优化设计程序经实例计算达到了重合度的设计目标。
曹雪梅, 周彦伟, 邓效忠, 张华
doaj
, 2018 在工程结构的可靠性优化过程中,求解的效率和精度是优化方法的关键。该文提出一种针对解耦优化的融合策略。所提方法在优化迭代解耦所用的失效概率函数为前几次迭代设计点构建的局部失效概率函数的加权融合形式。在对原可靠性优化问题进行解耦后,结合序列近似优化方法进行迭代求解。相比于常规的仅使用当次局部建立的失效概率函数而言,所提融合策略最大限度利用了各次迭代中产生的信息用于优化解耦求解,能够提高失效概率函数的近似精度,从而间接达到减少迭代次数和计算量的目的。最后给出了屋架和十杆结构的可靠性优化算例 ...
张保强, 朱海燕, 袁修开
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Comprehensive framework for assessing and optimizing existing research networks
Conservation Biology, EarlyView.Abstract Conservation, monitoring, and research networks, or collections of ecological research sites unified under a common mission of data collection or a research mission, are essential infrastructure for understanding large landscapes. However, most networks developed opportunistically over decades rather than through systematic design, creating ...
Alyson East +2 more
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Gaoya dianqi, 2011 针对电力变压器铁心柱截面优化问题,提出了一种新型优化设计方案。该新方案具有有效截面积更优、优化效果更好、利用率更高、铁心制造成本更低、减少能量损耗更多的优点,且考虑到散热性,对其进行了油道设计,实用性更强。
蒋雪峰 +5 more
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An Analysis of GAT′s Optimal Designing [PDF]
, 2001 【中文摘要】 通过作者最近建立的关于电力半导体器件 GAT的集电结耗尽层电位分布和电场分布的二维解析模型即《GAT栅屏蔽效应二维解析模型》、《GAT实现高频率与高基区穿通电压兼容特性分析》以及《GAT实现高电流增益与高雪崩击穿电压兼容特性分析》,定量研究了优化设计 GAT的材料参数和结构参数的关系。 【英文摘要】 By the aid of the two dimensional analytical model of the electric potential and field ...
庄宝煌 +3 more
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Geographic risks to functional groups of mammals and birds from habitat loss in Mexico
Conservation Biology, EarlyView.Abstract There is a need to quantify the impact of habitat loss due to anthropogenic factors on different aspects of biodiversity, such as functional trait diversity represented by functional groups (FGs). We developed a metric to assess the weighted risk of loss of habitat for 33 FGs of mammals and 36 FGs of birds in Mexico based on potential ...
Fernando Mayani‐Parás +4 more
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Gaoya dianqi, 1991 采用数学优化方法,对GIS用电流互感器的铁心尺寸进行优化设计,在给定条件下,以铁心和导线材料的成本为主要目标寻找既满足技术性能要求,又具有最佳经济效果的优化设计方案。
罗干平
doaj
Research on Travel Agency Business Model Innovation Based on the Media Integration——Xiamen Wenguang International Travel Agency as Sample [PDF]
, 2016 旅行社作为旅游产业关键要素之一，在旅游业发展中起着重要的支撑作用；而商务模式则主导着旅行社发展战略、具体经营管理以及品牌建设等，决定了旅行社的发展壮大。我国旅行社产业存在着分工重叠、模式类同、竞争优势/资源匹配不足等问题，极大压缩了旅行社的发展空间。因此，加强对旅行社商务模式的分析、优化创新，对于旅行社发展具有重要意义。 国内外已经对媒介、商务模式、整合营销、旅行社经营管理等进行了大量研究，并取得了媒介整合、旅行社商务模式创新、管理优化等研究成果。通过文献梳理，发现对于中小旅行社，基于优势资源来选用 ...
张仙娥
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Attainment Pairing Effects on Cognitive Conflict in Technology‐enhanced EFL Cooperative Tasks
International Journal of Applied Linguistics, EarlyView.ABSTRACT This study examines how attainment pairing (high‐high versus high‐low versus low‐low attainment) impacts English as a Foreign Language (EFL) learner engagement during technology‐enhanced cooperative writing tasks. Seventy‐eight Chinese university learners formed 39 dyads (13 pairs per group) via Tencent Meeting.
Ying Liu, Allen Thurston
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