Results 41 to 50 of about 32,954 (259)
地矿测绘, 2019 本文首先分析了测量上的函数误差模型,针对常用的非线性模型,研究了其常用的参数估计方法,并采用实例验算,论证了模型参数估计的正确性。
素贞 陈
semanticscholar +1 more source
Effect of uneven tolerance to human disturbance on dominance interactions of top predators
Conservation Biology, Volume 39, Issue 2, April 2025.Abstract Anthropogenic activities may alter felid assemblage structure, facilitating the persistence of tolerant species (commonly mesopredators), excluding ecologically demanding ones (top predators) and, consequently, changing coexistence rules. We aimed to determine how human activities influence intraguild relationships among top predators and ...
Pablo Villalva +2 more
wiley +1 more source
Pid controller for humidity control by modular air conditioning unit [PDF]
, 2015 组合式空调机组是烟草工业的重要动力设备，用以实现温湿度控制。本论文以厦门烟草工业有限责任公司的组合式空调机组为对象，针对湿度控制问题，研究PID控制的非线性改进及其算法与实现。文中首先介绍了组合式空调机组及其控制现状，并阐述了PID控制器的原理、控制算法以及几种常用参数整定方法；在此基础上，提出PID控制器的非线性改进及其算法；在实际的生产过程中，采用阶跃信号激励，获得了模型辨识的现场数据，并运用MATLAB软件进行参数辨识，从而获得了组合式空调机组湿度控制的数学模型；最后通过该模型进行数值仿真 ...
陈必辉
core
Forecasting stock returns with artificial neural networks(基于神经网络的股票收益率预测研究)
Zhejiang Daxue xuebao. Lixue ban, 2019 在金融领域的资产定价模型修正过程中，股市的非线性现象往往被选择性忽视，未纳入模型框架，现有模型亦无法刻画因子之间的非线性定价结构。为解决上述问题，引入了机器学习领域中的神经网络模型，以捕获市场组合收益率、市值、账面市值比三因子间的非线性定价结构，并对股票收益率进行预测。将该模型与经典 Fama-French 三因子模型在样本外拟合优度、多空策略业绩表现上做了对比，结果表明：神经网络模型能精准捕获市场组合收益率、市值、账面市值比3 个因子之间的非线性关系，且在样本外拟合优度 ...
PANShuiyang(潘水洋) +2 more
doaj +1 more source
Conservation Biology, Volume 39, Issue 2, April 2025.Abstract Emerging infectious diseases are increasingly recognized as a significant threat to global biodiversity conservation. Elucidating the relationship between pathogens and the host microbiome could lead to novel approaches for mitigating disease impacts.
Alexander S. Romer +25 more
wiley +1 more source
A systematic approach in analyzing sustained oscillations in an NF-kB signal transduction pathway system [PDF]
, 2010 Oscillation phenomenon is very common in biological systems. It is crucial to study oscillatory behaviors to understand gene regulation functions.
Lu, B. +2 more
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Social science integration at state and federal fish and wildlife organizations in the United States
Conservation Biology, Volume 39, Issue 2, April 2025.Abstract Increasingly, conservation professionals and scholars recognize the need for more holistic integration of social science in fish and wildlife management. This call is often framed around the complexity of 21st century conservation challenges and changing societal values toward fish and wildlife and its management.
Michael R. Quartuch +7 more
wiley +1 more source
Study on Characteristics of Quantum Dot Fiber laser and Photonic Crystal Fiber Nonlinear Lasers [PDF]
, 2015 光纤激光器因具备结构紧凑、光束质量好、高效率、高功率、高可靠性等优点被认为是最具潜力的激光源。本文对三种光纤激光光源做了系统的研究：基于纳米晶体量子点光纤激光器、基于光子晶体光纤四波混频效应的参量振荡器、以及光子晶体光纤非线性效应超连续谱光源。相对于传统的量子点随机激光器糟糕的激光模式和糟糕的输出激光方向，首先介绍了一种新型的量子点/光纤激光器，该激光器获得了光强分布集中的平顶模式的光束特性，对量子点激光器的集成化有重要的意义。随后在目前获得的基于光子晶体光纤四波混频的中红外转换效率非常低的背景下 ...
程辉辉
core
Guangtongxin yanjiu, 2015 设计了一种结构简单的高非线性低限制损耗PCF（光子晶体光纤）,其空气孔直径d=0.2μm,孔间距Λ=1.8μm。数值计算结果表明,通过在包层区域引入独特的四孔单元结构,在波长1.55μm处,非线性系数可达83.3W-1km-1,限制损耗低于10-9 dB/m,有效模场面积仅为1.46μm2,该PCF的高非线性效应与低限制损耗特性可以应用于超连续谱产生、非线性光学和光通信系统等领域。
张清淼, 谢丹, 熊磊
doaj