Results 11 to 20 of about 1,136,657 (134)

Auto-focus technology and its application based on image processing [PDF]

open access: yes, 2009
Auto-focusing technique is an important method to improve the precision,intelligentization,automatization for the indentation diameter measurement.The paper introduces an auto-focus method of indentation diameter measurement based on image processing ...
Chen, Xiaomei, Yang, Tao, Zuo, Yong
core   +3 more sources

不稳定腔的本征值与本征函数

open access: yes, 1979
本文证明了不稳定谐振腔的本征值与本征函数的存在性,并证明了不稳定腔的本征值与本征函数组成可数的无穷序列;同时,指出了文献[1]所提出的ε近似本征值与δ近似本征函数的概念并不能真实反映实际不稳定谐振腔的损失与场分布 ...
陈嗣熊
core   +2 more sources

卡门涡街的慢不稳定性

open access: yes, 1996
引进慢不稳定性概念,对卡门涡街的稳定性问题,进行了比较全面和细致的数值研究.首先用点涡模型做数值模拟,证实了早年卡门的线性稳定性分析结果,数值模拟卡门涡街的非线性稳定性却表明,卡门涡街对有限大小的扰动,表现出慢不稳定现象.然后用伪谱方法对涡街的形成进行直接数值模拟 ...
唐少杰, 忻鼎定, 庄逢甘
core   +2 more sources

Context‐Dependent Effects of Beavers (Castor spp.) on Freshwater Pearl Mussels (Margaritifera margaritifera) in European Rivers 河狸对欧洲河流中的淡水珍珠贝 (Margaritifera margaritifera) 存在情境依赖性影响

open access: yesWildlife Letters, EarlyView.
The study explores how beavers (Castor spp.) affect endangered freshwater pearl mussels (Margaritifera margaritifera) in European rivers. Beaver dams can harm small, fragmented mussel populations by reducing flow, increasing sediment, and potentially limiting host fish movement, while larger populations may benefit from improved bed stability and ...
Louise Lavictoire   +2 more
wiley   +1 more source

Methodology to identify ecologically matching areas and its applications in conservation planning

open access: yesConservation Biology, EarlyView.
Abstract Identifying ecologically matching areas is both challenging and critical for understanding spatial patterns of biodiversity and advancing conservation planning. However, existing approaches often lack spatial flexibility, overlook shape and size constraints, or rely on limited environmental parameters, reducing their effectiveness in real ...
Pietro Milanesi   +7 more
wiley   +1 more source

Scientists’ warning on the global destruction of rock outcrop ecosystems

open access: yesConservation Biology, Volume 40, Issue 5, October 2026.
Abstract Rock outcrops are geological formations that harbor a highly specialized biota adapted to harsh environmental conditions that differ from their surrounding landscapes. They are globally distributed, especially in old, highly weathered landscapes, and can function as habitat islands containing high levels of endemism and distinct evolutionary ...
Luiza F. A. de Paula   +19 more
wiley   +1 more source

激波稳定性(Ⅱ)

open access: yes, 1989
本文用D′yakov的normal mocle方法讨论任意状态方程介质中的平面定常激波在二维小扰动下的稳定性,用直接的数学方法和新的物理考虑导出激波稳定性与参数i~2(dv/dp)_H在不同流场条件下的关系,结果表明此关系比较复杂,而过去的D yakov-Erpenbeck不稳定条件只是一个极端情形。尤其是发现在参数i~2(dv/dp)_H的两个稳定区域之间还存在不稳定区域,而这正对应于Griffiths等的实验中所观察到的不稳定激波,将结果用于完全气体激波时发现当绝热指数r>5/3时激波可能不稳定 ...
黄迎雷
core   +2 more sources

Poverty, Inequality, and Social Security During the COVID‐19 Pandemic: Evidence From Linked Swiss Tax Data

open access: yesPoverty &Public Policy, Volume 18, Issue 3, September 2026.
ABSTRACT This paper examines the impact of the COVID‐19 pandemic on income and wealth inequality in Switzerland, with a particular focus on poverty dynamics and the role of the social security system. Using newly linked administrative tax data for four large cantons covering over a third of the Swiss population, we track changes in household income and
Oliver Hümbelin   +2 more
wiley   +1 more source

Policy Networks and Policy Entrepreneurship in the EU: Explaining Structural Policy Change in Pharmaceutical Innovation Incentives and Health Technology Assessment

open access: yesEuropean Policy Analysis, Volume 12, Issue 4, Fall 2026.
ABSTRACT Policy process research has excelled in explaining structural policy change within national settings, but extensions and applications to the EU level have long proven challenging for scholars. Given that the EU is currently experiencing its longest period of Treaty stability since the 1980s—having evolved into a sui generis political system ...
Vassilis Karokis‐Mavrikos
wiley   +1 more source

Wafer‐Scale Amorphous g‐C3N4 With Broadly Tunable Dielectric Properties for 2D Electronics

open access: yesRare Metals, Volume 45, Issue 7, July 2026.
ABSTRACT Two‐dimensional (2D) semiconductors are regarded as promising candidates for next‐generation electronics due to their superior electrostatic control; however, their performance is severely constrained by the lack of suitable dielectric materials.
Binyin Gao   +13 more
wiley   +1 more source

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