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240 nm AlGaN-based deep ultraviolet micro-LEDs:size effect versus edge effect

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Journal of Semiconductors 2024年第1期45卷 55-62页

作者： Shunpeng Lu Jiangxiao Bai Hongbo Li Ke Jiang Jianwei Ben Shanli Zhang Zi-Hui Zhang Xiaojuan Sun Dabing Li State Key Laboratory of Luminescence and Applications Changchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Key Laboratory of Electronic Materials and Devices of Tianjin School of Electronics and Information EngineeringHebei University of TechnologyTianjin 300401China

240 nm AlGaN-based micro-LEDs with different sizes are designed and ***,the external quantum efficiency(EQE)and light extraction efficiency(LEE)are systematically investigated by comparing size and edge ***,it is revealed that the peak optical output power increases by 81.83%with the size shrinking from 50.0 to 25.0μ***,the LEE increases by 26.21%and the LEE enhancement mainly comes from the sidewall light *** notably,transversemagnetic(TM)mode light intensifies faster as the size shrinks due to the tilted mesa side-wall and Al reflector ***,when it turns to 12.5μm sized micro-LEDs,the output power is lower than 25.0μm sized *** underlying mechanism is that even though protected by SiO2 passivation,the edge effect which leads to current leakage and Shockley-Read-Hall(SRH)recombination deteriorates rapidly with the size further ***,the ratio of the p-contact area to mesa area is much lower,which deteriorates the p-type current spreading at the mesa *** findings show a role of thumb for the design of high efficiency micro-LEDs with wavelength below 250 nm,which will pave the way for wide applications of deep ultraviolet(DUV)micro-LEDs.

关键词： AlGaN deep ultraviolet micro-LEDs light extraction efficiency size effect edge effect

Analytical solutions to edge effect of composite laminates based on symplectic dual system

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Applied Mathematics and Mechanics(English Edition) 2011年第9期32卷 1091-1100页

作者：姚伟岸聂臆瞩肖锋 State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Department of Computer Science Dalian Medical University

In the symplectic space composed of the original variables,displacements,and their dual variables,stresses,the symplectic solution for the composite laminates based on the Pipes-Pagano model is established in this *** contrast to the traditional technique using only one kind of variables,the symplectic dual variables include displacement components as well as stress ***,the compatibility conditions of displacement and stress at interfaces can be formulated *** being introduced into the symplectic dual system,the uniform schemes,such as the separation of variables and symplectic eigenfunction expansion method,can be implemented conveniently to analyze composite laminate *** analytical solution for the free edge effect of composite laminates is obtained,showing the effectiveness of the symplectic dual method in analyzing composite laminates.

关键词： composite laminates edge effect Pipes-Pagano model interlaminar stresses symplectic dual system

A PRELIMINARY STUDY ON FOREST edge effect AND APPLICATION

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Journal of Northeast Forestry University 1991年第1期2卷 17-23页

作者： Ding Baoyong Chen Xiangwei Wang Lu Liu QiangNortheast Forestry UniversityXiao JieMudanjiang Forestry Management Bureau of Heilongjiang Province Northeast Forestry University China Mudanjiang Forestry Management Bureau of Heilongjiang Province China

Researches and analyses were carried on the mechanism of forest edge effect by the classification of its types in forest ecosystem. Two kinds of practical models were put forward to extricate forestry from 'Two Crisises' and increase the utilization efficiency of solar energy and the net primary productivity on unit area by combination forest edge effect theory with forestry production. 1. Cultivating fast growth and rich yield plantation directionally in optimal community structure by use of forest edge effect theory. 2. Establishing artificial-natural compound forest community by openning up effect belts in natural secondary forest.

关键词： Forest ecosystem edge effect Classification Application

Study on the edge effect of Orthopteran Community in Ningxia Helan Mountain

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Agricultural Science & Technology 2010年第2期11卷 113-116,145页

作者：贺海明杨贵军何立荣王新谱宁夏大学科技处宁夏银川750021 宁夏大学生命科学学院宁夏银川750021 宁夏大学农学院宁夏银川750021 宁夏大学西北退化生态系统恢复与重建省部共建教育部重点实验室宁夏银川750021

[Objective] The study aimed to discuss the influences of edge effect on orthopteran community in east slope of Helan Mountain.[Method] Samples are collected by using sample zone *** different species of orthopterans in different habitats are recorded.[Result] The percentage of Oedipodidae,Catantopidae and Pamphgidae in total are 42.65%,29.15% and 12.76% *** scattered grassland interior to edge and then to desert grassland,abundance increase in turn,but diversity in the edge is the highe...

关键词： Orthoptera edge effect Diversity Scattered grassland-desert grassland Ecosystem Helan Mountain

edge effects on plant diversity in tropical forest ecosystems at Periyar Wildlife sanctuary in the Western Ghats of India

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Journal of Forestry Research 2013年第3期24卷 403-418页

作者： Somaiah Sundarapandian Pascal J. Karoor Department of Ecology and Environmental Sciences School of Life Sciences Pondicherry UniversityPuducherry India

Forest resource conservation has been widely accepted as a key to sustain the local and regional economic development. The forest edges are affected by anthropogenic activities including deforestation, forest fragmentation, selective logging, extraction of non-timber forest products, collection of medicinal plants, recreations, hydroelectric pro- jects and its associated developmental activities, which alter the biodiver- sity. The present study intends to evaluate the edge effect on vegetation structure and species compositions in the tropical forest ecosystems at Periyar Wildlife Sanctuary in the Western Ghats. High species richness （number of species） and Shannon＇s diversity indices were observed in the site IlI （completely undisturbed forest） compared to site I （adjacent to the village/edge of the forest, which is next to the teal（ plantation, severely disturbed forest） and site II （in between the undisturbed forest and mod- erately disturbed forest） while density of tree species showed greater value in site II. Single species such as Tectona grandis （IVI of 80） and Terminaliapaniculata （IVI of 112） were the dominant tree species in site I and site II, respectively, whereas, in site III Terminalia bellirica, Bishofia javanica and Syzgium gardneri shared the dominance. Perturba- tion leads to alien plant invasion particularly Lantana camara, Eupato- rium odoratum and Ageratum conizoides. Site II is at forest transition level because the site is dominated by both natural species as well as plantation species such as Tectona grandis. This site seems to be a buffer zone on natural forest and plantations. Further studies are required to analyse the real patterns of regeneration and dynamic change due to human impact by long term monitoring with the establishment of perma- nent plots.

关键词： anthropogenic disturbance biodiversity edge effect tropi-cal forest Western Ghats

Electronic structures and edge effects of Ga_2S_2 nanoribbons

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Chinese Physics B 2016年第10期25卷 308-313页

作者：王宝基李晓华张利伟王国东柯三黄 School of Physics and Electronic Information Engineering Henan Polytechnic University MOE Key Labortoray of Microstructured Materials School of Physics Science and Engineering Tongji University Beijing Computational Science Research Center

Ab initio density functional theory calculations are carried out to predict the electronic properties and relative stability of gallium sulfide nanoribbons(Ga2S2-NRs) with either zigzag- or armchair-terminated edges. It is found that the electronic properties of the nanoribbons are very sensitive to the edge structure. The zigzag nanoribbons(Ga2S2-ZNRs)are ferromagnetic(FM) metallic with spin-polarized edge states regardless of the H-passivation, whereas the bare armchair ones(Ga2S2-ANRs) are semiconducting with an indirect band gap. This band gap exhibits an oscillation behavior as the width increases and finally converges to a constant value. Similar behavior is also found in H-saturated Ga2S2-ANRs,although the band gap converges to a larger value. The relative stabilities of the bare ANRs and ZNRs are investigated by calculating their binding energies. It is found that for a similar width the ANRs are more stable than the ZNRs, and both are more stable than some Ga2S2nanoclusters with stable configurations.

关键词： density functional theory Ga_2S_2 nanoribbon electronic structure edge effect

Urbanization strengthens the edge effects on species diversity and composition of woody plants in remnant forests

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Forest Ecosystems 2022年第5期9卷 657-665页

作者： Zijin Wang Jingyi Yang College of Forestry Guizhou UniversityGuiyang550025China

Background:Urban remnant forests are embedded in urban areas and are threatened directly and indirectly by *** direct effects(e.g.,loss of area)have been well ***,knowledge about the indirect influence of urbanization through edge effects on the biodiversity in remnant forests is ***:In this study,we surveyed woody plant species in 72 plots in nine remnant forest patches in Guiyang,*** examined the influences of urbanization and edge effects on the species diversity and composition of woody plants in remnant *** compared alpha diversities and quantified compositional dissimilarities in interior and edge sites at different levels of *** also measured the niche width of the recorded plant species and assessed whether high levels of urbanization and edge effects increased the number of generalist *** and conclusions:The Shannon index,the Simpson index and the Pielou index of adult trees were lowest in the edge habitat under high levels of *** differences in the Shannon index and the Simpson index of sapling/seedling were detected between interior and edge sites under low *** edge effects on the species composition of adult trees were intensified by high levels of *** plant species with wide niche widths were more abundant at edge sites under high levels of ***,we recommend that urban expansion surrounding remnant patches should be strictly controlled to alleviate edge effects on biodiversity.

关键词： Remnant forest Urbanization edge effect Species diversity and composition Niche width Guiyang

Natural vegetation cover in the landscape and edge effects： differential responses of insect orders in a fragmented forest

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Insect Science 2017年第5期24卷 891-901页

作者： Ezequiel Gonzalez Adriana Salvo Graciela Valladares Centro de Investigaciones Entomologicas de Cordoba IMBIV UNC CONICET FCEFyN Av. Velez Sarfield 1611 Cordoba CordobaX5000GMC Argentina

Human activities have led to global simplification of ecosystems, among which Neotropical dry forests are some of the most threatened. Habitat loss as well as edge effects may affect insect communities. Here, we analyzed insects sampled with pan traps in 9 landscapes （at 5 scales, in 100-500 m diameter circles） comprising cultivated fields and Chaco Serrano forests, at overall community and taxonomic order level. In total 7043 specimens and 456 species of hexapods were captured, with abundance and richness being directly related to forest cover at 500 m and higher at edges in comparison with forest interior. Community composition also varied with forest cover and edge^interior location. Different responses were detected among the 8 dominant orders. Collembola, Hemiptera, and Orthoptera richness and^or abundance were positively related to forest cover at the larger scale, while Thysanoptera abundance increased with forest cover only at the edge. Hymenoptera abundance and richness were negatively related to forest cover at 100 m. Coleoptera, Diptera, and Hymenoptera were more diverse and abundant at the forest edge. The generally negative influence of forest loss on insect communities could have functional consequences for both natural and cultivated systems, and highlights the relevance of forest conservation. Higher diversity at the edges could result from the simultaneous presence of forest and matrix species, although ＂resource mapping＂ might be involved for orders that were richer and more abundant at edges. Adjacent crops could benefit from forest proximity since natural enemies and pollinators are well represented in the orders showing nositive edge effects.

关键词： Chaco Serrano edge effect forest cover habitat loss insects orders

Arthropods on plants in a fragmented Neotropical dry forest： A functional analysis of area loss and edge effects

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Insect Science 2015年第1期22卷 129-138页

作者： Ezequiel Gonzalez Adriana Salvo Graciela Valladares Centro de Investigaciones Entomol6gicas de C6rdoba (IMBIV - CONICET) and Universidad Nacional de C6rdoba C6rdoba Argentina

Loss and fragmentation of natural ecosystems are widely recognized as the most important threats to biodiversity conservation, with Neotropical dry forests among the most endangered ecosystems. Area and edge effects are major factors in fragmented landscapes. Here, we examine area and edge effects and their interaction, on ensembles of arthropods associated to native vegetation in a fragmented Chaco Serrano forest. We analyzed family richness and community composition of herbivores, predators, and parasitoids on three native plant species in 12 fragments of varying size and at edge/interior positions. We also looked for indicator families by using Indicator Species Analysis. Loss of family richness with the reduction of forest fragment area was observed for the three functional groups, with sirnilar magnitude. Herbivores were richer at the edges without interaction between edge and area effects, whereas predators were not affected by edge/interior position and parasitoid richness showed an interaction between area and position, with a steeper area slope at the edges. Family composition of herbivore, predator, and parasitoid assemblages was also affected by forest area and/or edge/interior situation. We found three indicator families for large remnants and five for edges. Our results support the key role of forest area for conservation of arthropods taxonomic and functional diversity in a highly threatened region, and emphasize the need to understand the interactions between area and edge effects on such diversity.

关键词： area loss Chaco Serrano edge effect forest arthropods functional groups habitat fragmentation