Results 41 to 50 of about 18,698 (136)
Conservation Biology, EarlyView.Abstract Consumer demand for ivory perpetuates the unsustainable and illegal killing of African elephants and other wildlife species. Interventions that aim to change consumer behavior are increasingly recognized as a crucial element of demand management. However, poor design and implementation have limited their effectiveness.
Molly R. C. Brown +2 more
wiley +1 more source
Computational and theoretical analysis of supervised dimensionality reduction(监督降维算法的计算和理论分析)
Zhejiang Daxue xuebao. Lixue ban, 2009 在小样本条件下,由于离散矩阵的奇异性,作为监督降维的传统线性鉴别分析(LDA)并不能直接计算.许多扩展算法被提出以克服此问题,一般可分为3类：基于类内离散矩阵零空间的方法、基于总体离散矩阵列空间的方法和基于其它子空间的方法.为了深入了解前2类算法的特性,作了计算和理论分析,并得出结论：在满足一定条件下（小样本高维数据一般都满足）,基于类内离散矩阵零空间和基于总体离散矩阵列空间的方法具有等价关系,仅最优矢量集的约束条件和实现途径有所区别.在人脸数据库ORL和YALE上的比较实验结果亦证实了上述结论.
ZHAOWu-feng(赵武锋) +2 more
doaj +1 more source
, 2012 将基本解方法推广到二阶和四阶椭圆型偏微分方程的对称问题,在边界上不需要处理奇异积分.通过坐标变换,将一般二阶和四阶椭圆型偏微分方程化为目前研究较为成熟的调和或双调和方程.再根据镜像法构造出适合对称条件的基本解函数,简化了计算,且不影响计算的精度.通过数值计算结果可以看出,利用镜像技术构造出的基本解,前期准备数据少,可保持精度 ...
周志东, 蒋泉, 魏海娥
core
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
wiley +1 more source
Representation of obligate groundwater‐dwelling copepod diversity in European protected areas
Conservation Biology, EarlyView.Abstract Groundwaters sustain diverse surface ecosystems and are populated by metazoan species, mostly invertebrates, that provide fundamental ecological functions and are often of prominent conservation value due to narrow endemism and high phylogenetic rarity.
Francesco Cerasoli +7 more
wiley +1 more source
Conservation Biology, EarlyView.Abstract In the western United States, conservation practitioners are increasingly working with private landowners to restore habitat for North American beavers (Castor canadensis) and to use nonlethal mitigation techniques when beavers damage crops and infrastructure.
Brian D. Erickson, Megan S. Jones
wiley +1 more source
Gaoya dianqi, 2018 为了进一步提高基于油中溶解气分析的变压器故障诊断准确率,提出了一种基于模糊聚类和主成分分析的故障诊断方法。该方法首先利用模糊C均值聚类方法对搜集的DGA样本集进行聚类分析,将聚类中心矩阵作为标准故障谱。然后采用改进型主成分分析方法精简样本矩阵信息,通过计算样本主成分间欧拉距离确定故障类型。通过实例验证证明本文方法能有效识别故障类型,且较IEC比值法、改良三比值法等具有更高的准确率。该方法为变压器故障诊断提供了新思路,具有一定的实际应用价值。
覃煜, 黄慧红, 方健, 陈雁
doaj
Zhejiang Daxue xuebao. Lixue ban, 2017 第二类柯西奇异积分方程因涉及复奇异因子往往造成求解困难，而适用第一类奇异积分方程的高效数值方法并不能推广至第二类奇异积分方程，即便是第二类奇异积分方程，其数值解法仍是一个难题.为此提出了构造第二类奇异积分方程解析解的一种新方法.通过分解柯西奇异项，并利用雅克比多项式的正交性，推导针对右端载荷项为单项式(monomial)的递推解析解，进而借助级数展开的方法推广至一般的载荷问题.提出的基于递推的解析解构造方案，能完美地结合maple软件编程，从而提供一种方便、快捷、有效的算法.由给出的算例可见 ...
JINXiaoqing(金晓清) +5 more
doaj +1 more source
International Journal of Applied Linguistics, EarlyView.ABSTRACT Research on English‐Medium‐Instruction (EMI) highlights inadequate support for students transitioning from L1‐medium‐instruction to EMI. To date, little research has focused on how L2 students’ adaptation to an EMI environment influences their L2 learning motivation (LLM).
Kevin W. H. Tai
wiley +1 more source
Dizhen xuebao, 2019 本文提出了一种基于L1范数正则化的基线校正新方法，即以拟合速度时程误差最小为目标，以基线漂移本身尽可能小为约束条件，经过凸优化多次迭代自动求解出满足条件的基线漂移，避免了人为选取基线漂移分段次数和基线漂移起止时刻的主观干扰；随后利用该方法对多组加入了基线漂移噪声模型的强震动加速度记录进行验证。结果表明：本文方法对于识别和处理单段式、两段式和多段式的基线漂移噪声具有普适性，能敏锐地捕捉到速度时程发生漂移的趋势（斜率变化），无需预先设定加速度基线漂移模型也可有效地识别出多种基线漂移噪声的起止位置和漂移程度 ...
Zhenghui Xiong +3 more
doaj +1 more source