Results 41 to 50 of about 11,348 (173)
, 2018 在模糊控制的实际应用中,隶属函数的选取往往依靠专家经验设定。这使得模糊控制由于隶属函数设定复杂,加大了实际应用的难度,往往达不到较好的控制效果。本文从RBF神经网络的特点出发,使用差分进化算法分成两个部分来优化RBF神经网络的参数,使之可以自动设置模糊控制的隶属函数。再通过模糊控制实时调整的PID控制器的三个参数,并分别对二阶系统和倒立摆系统进行仿真模拟。简化了模糊控制的设置方法,提高了进化算法在优化神经网络参数过程中的计算效率,取得了较好的控制效果。福建省高校产学合作项目 ...
何俊杰, 刘畅, 肖可, 陈松岩
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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
wiley +1 more source
Shuitu Baochi Xuebao, 2011 通过对荒漠草原4种典型植物群落(蒙古冰草群落、甘草群落、赖草群落、沙蒿群落)枯落物蓄积量的调查,结合室内持水试验,运用数理统计的方法分别得到4种典型植物群落枯落物的蓄积量、最大持水量、吸水速率等水文特征参数。结果表明:荒漠草原不同植物群落枯落物蓄积量在50.8～396.2g/m2,其蓄积量由大到小为蒙古冰草群落>甘草群落>赖草群落>沙蒿群落,与植物群落地上生物量变化是一致的;4种植物群落枯落物最大持水量存在一定差异,蒙古冰草群落、甘草群落、赖草群落、沙蒿群落枯落物最大持水量分别相当于0.934,0 ...
李学斌 +6 more
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The biotoxic effect of ZnO nanoparticles on three zooplankton [PDF]
, 2017 纳米氧化锌（ZnO-NPs）因其特殊的理化性质而在化妆品、医学抗菌、工业涂料等领域被广泛应用。其通过工业生产、商品使用、空气沉降、运输泄露、地表水径流等途径直接或间接汇入海洋环境，对海洋的生态系统构成潜在威胁。海洋中的浮游动物可以通过摄食影响或控制初级生产力，同时它们的种群动态变化又影响许多鱼类和其他动物资源群体的生物量。开展纳米氧化锌对浮游动物的毒性效应研究，对于了解纳米材料在水体中行为、评价浮游动物对纳米材料的响应、实现纳米材料环境危害性的合理评估具有十分重要的意义 ...
余东林
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Conservation Biology, EarlyView.Abstract The design of experiments to investigate the combined effects of multiple stressors requires exposing target organisms to multiple combinations of stressor doses. Concurrent manipulation of stressors is often infeasible with wildlife, but long‐lasting health effects allow individual health to be used as an integrator of prior stressor exposure.
Enrico Pirotta +24 more
wiley +1 more source
Shuitu Baochi Xuebao, 2007 植被恢复是退化生态系统重建的重要途径，植被恢复过程中物种多样性的变化反映了植被的恢复程度，通过群落调查，研究了太行山片麻岩区植被恢复过程中群落物种多样性特征及其与土壤含水量之间的关系，结果表明：物种多样性指数天然灌木群落〉人工乔木群落。乔木和灌木群落各指数大小为封禁20年〉封禁10年〉封禁5年。6种群落其土壤含水量均偏低，随着封禁时间的加长，含水量略为增加，但天然灌木群落平均含水量稍大于人工群落。不同封禁时间群落土壤含水贯与均匀度指数成正相关，多样性指数与含水量先呈正相关，在封禁20年时，呈负相关 ...
徐学华 +4 more
doaj
, 2007 通过线粒体Cytb基因全序列分析,探讨了青海湖裸鲤和花斑裸鲤的起源关系及其进化模式.系统发育分析进一步支持了青海湖裸鲤和花斑裸鲤3个mtDNA谱系的划分.形态上具有高鳃耙变异的个体未形成特有的进化枝,证明了第一鳃弓外鳃耙变异并不具有系统发育意义.对青海湖裸鲤和花斑裸鲤进化枝扩散模式的网络分析表明,黄河独有的单倍型A1是一个创立者单倍型,全部青海湖裸鲤的样品来自于它的辐射,而青海湖裸鲤可能仅仅起源于黄河花斑裸鲤两个主要支系中的一个 ...
何舜平 +5 more
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Conservation Biology, EarlyView.Abstract Constructed value of information (CVoI) is an expert elicitation decision‐analytic tool used to prioritize sources of uncertainty based on their potential to improve decision outcomes if resolved. Despite increased application of CVoI, the robustness of CVoI prioritization of sources of uncertainty relative to differences in expert elicitation
Kristin P. Davis +7 more
wiley +1 more source
, 2012 利用泥鳅(Misgurnus anguillicaudatus)的微卫星引物跨种扩增大鳞副泥鳅(Paramisgurnus dabryanus),通过家系扩增、PCR产物测序筛选出6个座位,用于大鳞副泥鳅7个野生群体的遗传结构分析。结果显示,群体的平均等位基因数在3.167～4.833,平均观测杂合度(Ho)在0.248～0.417,平均期望杂合度(He)在0.379～0.505,多个座位存在零等位基因、杂合子缺失现象,显示大鳞副泥鳅种群遗传多样性较低。采用UPGMA法对7个群体基于DA遗传距离进行聚类,
俞小牧, 游翠红, 童金苟
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Biodiversity‐driven spatial conservation planning to delineate temporally stable regions
Conservation Biology, EarlyView.Abstract The accelerating loss of biodiversity underscores the critical need for effective conservation strategies, particularly in the face of climate change and anthropogenic pressures. We devised a conservation planning framework that adopts a temporal stacking approach to species distribution models and landscape connectivity analyses. These models
Mattia Iannella +5 more
wiley +1 more source