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Optimization of Nesting Systems in Shipbuilding:A Review 认领 引用
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作者 Sari Wanda Rulita Gunawan Muzhoffar Dimas Angga Fakhri 《哈尔滨工程大学学报（英文版）》 CSCD 2025年第1期152-175,共24页
This review article provides a comprehensive analysis of nesting optimization algorithms in the shipbuilding industry,emphasizing their role in improving material utilization,minimizing waste,and enhancing production ... This review article provides a comprehensive analysis of nesting optimization algorithms in the shipbuilding industry,emphasizing their role in improving material utilization,minimizing waste,and enhancing production efficiency.The shipbuilding process involves the complex cutting and arrangement of steel plates,making the optimization of these operations vital for cost-effectiveness and sustainability.Nesting algorithms are broadly classified into four categories:exact,heuristic,metaheuristic,and hybrid.Exact algorithms ensure optimal solutions but are computationally demanding.In contrast,heuristic algorithms deliver quicker results using practical rules,although they may not consistently achieve optimal outcomes.Metaheuristic algorithms combine multiple heuristics to effectively explore solution spaces,striking a balance between solution quality and computational efficiency.Hybrid algorithms integrate the strengths of different approaches to further enhance performance.This review systematically assesses these algorithms using criteria such as material dimensions,part geometry,component layout,and computational efficiency.The findings highlight the significant potential of advanced nesting techniques to improve material utilization,reduce production costs,and promote sustainable practices in shipbuilding.By adopting suitable nesting solutions,shipbuilders can achieve greater efficiency,optimized resource management,and superior overall performance.Future research directions should focus on integrating machine learning and real-time adaptability to further enhance nesting algorithms,paving the way for smarter,more sustainable manufacturing practices in the shipbuilding industry. 展开更多
关键词 Cutting plate Nesting algorithms Nesting optimization Shipbuilding efficiency Algorithmic optimization
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Two-Dimensional Nesting System Based on Hybrid Genetic Algorithm 认领 引用
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作者 WU Qingming YANG Wei ZHANG Qiang ZHOU Junjie 《Wuhan University Journal of Natural Sciences》 CAS 2009年第1期60-64,共5页
According to the cutting stock problem of 2-dimensional shapes, a nesting system （NS） based on hybrid genetic algorithm （HGA） is established. The system optimizes the sequence and angles of polygons with hybrid Ge... According to the cutting stock problem of 2-dimensional shapes, a nesting system （NS） based on hybrid genetic algorithm （HGA） is established. The system optimizes the sequence and angles of polygons with hybrid Genetic Algorithm to accomplish the superior solution. It nests the irregular shape directly without covering irregular shapes with a rectangle. It also improves the decoding strategy of 2-dimensional shapes nesting based on the classical bottom-left strategy, makes the new strategy be universal to convex polygons, concave polygons and line-circular composted polygons. 展开更多
关键词 nesting system hybrid genetic algorithm （HGA） regular and circular polygon bottom-left strategy
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Characteristics and driving factors of population age structure in China:A study based on the scale nesting theory 认领 引用
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作者 YING Kui HA Lin +1 位作者 DUAN Liancheng DING Jinhong 《Journal of Geographical Sciences》 SCIE CSCD 2026年第5期1278-1298,共21页
China's population age structure(PAS)has already entered a modern phase,with the effects of aging and declining birth rates becoming increasingly severe.These trends pose significant challenges to demographic and ... China's population age structure(PAS)has already entered a modern phase,with the effects of aging and declining birth rates becoming increasingly severe.These trends pose significant challenges to demographic and socioeconomic stability.In this study,the scale nesting theory was used to analyze the population census data for 2000-2020 from prefecture-level cities.Using a multiscale geographically weighted regression model,this study explores the spatial characteristics of China's age structure and quantitatively examines the driving factors within this nested framework.The evolution of PAS in the prefecture-level cities in China exhibited distinct stages,while depicting a rapid transition toward an aging model.In the nested space,single-scale nesting was primarily synchronous,while double-scale nesting was characterized by simultaneous synchronization.The Northeast region exhibited the highest degree of synchronous development in the PAS within the nested space.The regression coefficients indicated that the population system and per capita gross domestic product(GDP)were the primary and secondary factors,respectively.Topographical variation exerted an influence on only the synchronous-advance type,while PM2.5exhibited a significant association with the advance-lag type.This study provides scientific support for high-quality development across regions in the context of heterogeneous population age structures. 展开更多
关键词 age structure spatio-temporal characteristics scale nesting driving factors
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Adapting to the concrete jungle:Urbanization increases the use of anthropogenic nesting materials by Azure-winged Magpies(Cyanopica cyanus) 认领 引用
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作者 Fudong Zhou Hong Wang Jianping Liu 《Avian Research》 SCIE CAS CSCD 2026年第3期578-586,共9页
Rapid urbanization has resulted in a substantial decrease in natural habitats,posing considerable challenges to bird survival.Bird nests,which are temporary structures used for breeding,reflect adaptation strategies b... Rapid urbanization has resulted in a substantial decrease in natural habitats,posing considerable challenges to bird survival.Bird nests,which are temporary structures used for breeding,reflect adaptation strategies based on their material composition.However,how urban expansion influences the selection of nest materials—particularly the incorporation of anthropogenic nesting materials—remains poorly understood,limiting our understanding of species'adaptive strategies in human-dominated landscapes.To address this knowledge gap,this study examined the nest material characteristics of 432 Azure-winged Magpie(Cyanopica cyanus)nests in Wuhan,Hubei Province,China,to assess the influence of urbanization on nest material selection.Azure-winged Magpies utilized diverse nest materials,mainly branches,moss,soil,polyester fibers,and plastics.Furthermore,nest weight markedly varied among the urban centers,outskirts,and rural areas,with nests in urban centers and outskirts being substantially lighter than those in rural areas.Particularly,the weight of natural nest materials(NNMs)in urban centers and outskirts was considerably lower than that in rural areas,whereas the weight of anthropogenic nesting materials(ANMs)in urban centers did not markedly differ from that in rural areas but was notably higher than that in the outskirts.Across all the three areas,the NNM proportion was substantially higher than that of ANMs.Among ANMs,polyester fibers and plastics constituted relatively high proportions.Furthermore,the weight of ANMs reduced as the distance between the nests and buildings increased.Thus,urbanization may affect the nest material selection of Azure-winged Magpies,showing their behavioral adjustments to urbanization pressures and ecological strategies for using local resources.This study provides a scientific basis for urban biodiversity conservation. 展开更多
关键词 Anthropogenic nesting materials Azure-winged Magpie Natural nest materials Nest material selection Urbanization
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Modelling the nesting-habitat of threatened vulture species in the caucasus:An ecosystem approach to formalising environmental factors in species distribution models 认领 引用 被引量：2
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作者 Rustam Pshegusov Victoria Chadaeva 《Avian Research》 SCIE CSCD 2023年第4期572-585,共14页
Abiotic factors play an important role in species localisation,but biotic and anthropogenic predictors must also be considered in distribution modelling for models to be biologically meaningful.In this study,we formal... Abiotic factors play an important role in species localisation,but biotic and anthropogenic predictors must also be considered in distribution modelling for models to be biologically meaningful.In this study,we formalised the biotic predictors of nesting sites for four threatened Caucasian vultures by including species distribution models(wild ungulates,nesting tree species)as biotic layers in the vulture Maxent models.Maxent was applied in the R dismo package and the best set of the model parameters were defined in the R ENMeval package.Performance metrics were continuous Boyce index,Akaike's information criterion,the area under receiver operating curve and true skill statistics.We also calculated and evaluated the null models.Kernel density estimation method was applied to assess the overlap of vulture ecological niches in the environmental space.The accessibility of anthropogenic food resources was estimated using the Path Distance measure that considers elevation gradient.The availability of pine forests(Scots Pine)and wild ungulates(Alpine Chamois and Caucasian Goat)contributed the most(29.6%and 34.3%)to Cinereous Vulture(Aegypius monachus)nesting site model.Wild ungulate distribution also contributed significantly(about 46%)to the Bearded Vulture(Gypaetus barbatus)model.This scavenger nests in the highlands of the Caucasus at a minimum distance of 5–10 km from anthropogenic facilities.In contrast,livestock as a food source was most important in colony distribution of Griffon Vulture(Gyps fulvus).The contribution of distances to settlements and agricultural facilities to the model was 45%.The optimal distance from Egyptian Vulture(Neophron percnopterus)nesting sites to settlements was only 3–10 km,to livestock facilities no more than 15 km with the factor contribution of about 57%.Excluding the wild ungulate availability,the ecological niches of studied vultures overlapped significantly.Despite similar foraging and nesting requirements,Caucasian vultures are not pronounced nesting and trophic competitors due to the abundance of nesting sites,anthropogenic food sources and successful niche sharing. 展开更多
关键词 Caucasian vultures Ecological niche differentiation Maxent Nesting sites Species distribution models
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Erratum: Fermi Surface Nesting with Heavy Quasiparticlesin the Locally Noncentrosymmetric Superconductor CeRh2As2 认领 引用
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作者 Yi Wu Yongjun Zhang +15 位作者 Sailong Ju Yong Hu Yanen Huang Yanan Zhang Huali Zhang Hao Zheng Guowei Yang Evrard-Ouicem Eljaouhari Baopeng Song Nicholas CPlumb Frank Steglich Ming Shi Gertrud Zwicknagl Chao Cao Huiqiu Yuan Yang Liu 《Chinese Physics Letters》 SCIE EI CAS CSCD 2025年第4期188-188,共1页
In the acknowledgements,[1]the first acknowledged grant number(2022YFA140220)is incorrect and should be changed to 2022YFA1402200.
关键词 fermi surface nesting locally noncentrosymmetric superconductor cerh heavy quasiparticles
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Pressure-Induced Novel bcc Crystal Structure with High Tc in Nb-Ti System 认领 引用
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作者 Mengxin Yang Jiajin Chen +7 位作者 Bohan Cao Xiaoqian Gai Yugang Su Xinwei Wang Shi Chen Liang Guo Defang Duan Fubo Tian 《Chinese Physics Letters》 SCIE EI CAS CSCD 2025年第6期239-254,共16页
The high-pressure phase diagram of the Nb-Ti binary system at 0 K is explored by systematic crystal structure prediction.The results highlight a novel niobium-rich bcc phase,Nb7Ti,which is the only dynamically stab... The high-pressure phase diagram of the Nb-Ti binary system at 0 K is explored by systematic crystal structure prediction.The results highlight a novel niobium-rich bcc phase,Nb7Ti,which is the only dynamically stable ordered Nb-Ti compound under ambient pressure.Extensive first-principles calculations have provided insights into the electronic structure,bonding and superconducting properties of Nb7Ti.The superconducting transition temperature(Tc)for Nb7Ti at ambient pressure is estimated within the framework of BCS theory to be about 17.5 K,which is significantly higher—nearly double—that of the widely utilized NbTi alloy.Furthermore,the results unveil that the high Tc is mainly attributed to the unique ordered lattice along with the strong electron-phonon coupling driven by interatomic interactions at mid-frequency and phonon softening induced by low-frequency Fermi surface nesting.Valuable insights are provided for the subsequent synthesis of application-oriented superconductors at low pressure. 展开更多
关键词 fermi surface nesting nb ti superconducting transition temperature electron phonon coupling systematic crystal structure predictionthe ambient pressure pressure induced bcc phase low frequency phonon softening
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Nesting and Berth Allocation by an Expert System Using Heuristic Search 认领 引用
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作者 Dongmok Sheen Yoonho Seo 《Journal of Software Engineering and Applications》 2017年第4期311-323,共13页
Nesting is a common problem in industries such as shipbuilding, auto-maker, clothing, shoe-making, and furniture, in which various parts are cut off from a stock or stocks while minimizing the wastes or maximizing the... Nesting is a common problem in industries such as shipbuilding, auto-maker, clothing, shoe-making, and furniture, in which various parts are cut off from a stock or stocks while minimizing the wastes or maximizing the utilization of the stock. Berth allocation at seaside is also considered one form of two dimensional nesting problems, in which a ship is assigned a location for service during a certain time slot. This paper presents an expert system using a heuristic search method for nesting problems. The parts and stocks are represented by pixels with which utility function is used to evaluate current state in search tree. The system is developed in CLIPS, an expert system shell and applied to various example problems with different constraints and to a berth allocation example to illustrate its applicability under different conditions. 展开更多
关键词 Nesting Berth Allocation Heuristic Search CLIPS
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Precisely targeting host activity for parasitism by Common Cuckoos 认领 引用
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作者 Guo Zhong Guixia Wan +1 位作者 Longwu Wang Wei Liang 《Avian Research》 SCIE CAS CSCD 2026年第2期347-353,共7页
The evolution of parasitic strategies through tracking host life-history patterns represents a key adaptive trait in avian brood parasites.However,when hosts successfully exploit human-modiffiified environments—such ... The evolution of parasitic strategies through tracking host life-history patterns represents a key adaptive trait in avian brood parasites.However,when hosts successfully exploit human-modiffiified environments—such as diverse and concealed nesting sites—the mechanisms enabling cuckoos(Cuculus spp.)to accurately locate and parasitize such nests remains unclear.The Daurian Redstart(Phoenicurus auroreus),a human-commensal secondary cavitynester,often breeds in diverse artiffiificial structures—leading to variable and concealed nest locations—making it an ideal system to study this question.Using long-term ffiifield monitoring and a nestbox attraction experiment,we investigated how Common Cuckoos(Cuculus canorus)locate and parasitize such concealed nests.Our results show no signiffiificant variation in Common Cuckoo parasitism rates across different natural nesting sites.However,nestboxes that were more exposed experienced higher parasitism rates than natural nests.Furthermore,cuckoos targeted exclusively those boxes with active host attendance,rather than boxes occupied by other species.This study provides the ffiifirst evidence of cuckoo parasitism on a human-associated host nesting indoors,underscoring the key role of host activity cues and suggesting that cuckoos,like their hosts,are also adapting to anthropogenic refuges. 展开更多
关键词 Anthropogenic refuges Host active cue Nest concealment Parasitic adaption
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Synergetic catalysis between ZnZrOₓ and silanol nest‑enriched silicalite‑1 in CO₂ hydrogenation coupled with toluene alkylation 认领 引用
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作者 Yuhang Guo Weichao Qin +3 位作者 Ruiwen Cao Linfeng Zhang Tingjun Fu Zhong Li 《ENGINEERING Chemical Engineering》 SCIE EI CAS CSCD 2026年第7期83-100,共18页
CO₂ hydrogenation coupled with toluene alky‑lation is a promising route for application in greenhouse gas utilization and para‑xylene(PX)production;however,the strong Brønsted acid sites of the conventional ZSM‑5... CO₂ hydrogenation coupled with toluene alky‑lation is a promising route for application in greenhouse gas utilization and para‑xylene(PX)production;however,the strong Brønsted acid sites of the conventional ZSM‑5 catalyst lead to uncontrollable(de)alkylation and xylene isomerization.In this study,a silanol nest‑enriched silica‑lite‑1 zeolite(AS‑1)with a moderate acidity was employed as an alkylation catalyst to suppress side reactions.Dealkylation and xylene isomerization were significantly suppressed compared to those observed using ZSM‑5,which reduced the benzene selectivity from 6.04%to 0.5%and increased the PX selectivity from 23.6%to 33%.An epitaxial silicalite‑1 shell was introduced to passivate the external sites to enhance the shape‑selective effect of AS‑1,thus improving the PX selectivity from 36.2%to 44.4%.The intimate contact established by optimizing the spatial distribution facilitated the conversion of the methanol intermediates,increasing the toluene conversion to 16.3%.A deposition‑precipitation strategy was adopted to load ZnZrOₓ particles onto silicalite‑1 zeolite‑coated AS‑1,which increased the ZnZrOₓ dispersion and minimized the transfer distance for the methanol intermediates.Consequently,considerable levels of toluene conversion and a high PX selectivity of 15%and 42.7%,respectively,were maintained,while the CO₂ conversion significantly increased from 5.9%to 9.5%.Additionally,ammonium hexafluorosilicate treatment generated small mesopores within the AS‑1 zeolite,which enhanced diffusion and further increased the toluene conversion to 20.9%.This study provides novel insights into the design of bifunctional catalysts comprising silanol nest‑enriched silicalite‑1 and ZnZrOₓ for use in CO₂ hydrogenation coupled with toluene alkylation. 展开更多
关键词 silanol nest CO₂hydrogenation bifunctional catalysts silicalite‑1
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Optimization of ecological networks considering watershed constraints and cross-domain synergies:A case study of Wuhan 认领 引用
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作者 Jinting Zhang Shan Liao +4 位作者 Kui Yang Senpeng Wang Yaoxuan Zhang Xiu Wu Lizhi Peng 《Ecological Frontiers》 CSCD 2026年第2期744-758,共15页
Landscape fragmentation,habitat loss,and blocked ecological corridors threaten regional ecological security and sus-tainable development.Ecological networks(ENs)are vital for addressing these challenges,but most studi... Landscape fragmentation,habitat loss,and blocked ecological corridors threaten regional ecological security and sus-tainable development.Ecological networks(ENs)are vital for addressing these challenges,but most studies focus on single administrative regions,overlooking landscape continuity and cross-domain synergies.This study takes Wuhan as an example,contrasting watershed buffers and distance buffers to construct multi-magnitude ecological net-works,analyzing their nesting and coordination characteristics with the city's ecological network,and exploring opti-mization paths for cross-district ecological networks.The research uses habitat quality evaluation,the least cumulative resistance model,and circuit theory to extract ecological elements,and assesses coordination and mismatch through the Spatial Mismatch Index(SMI)and Network Nested Index(NNI).Results show that the NNI stabilizes when the wa-tershed buffer reaches the fourth tier or the distance buffer extends to 75 km,identifying these as optimal thresholds.The watershed area of 4.17418×102km2overlaps with Wuhan's ecological sources,forming a key protection zone,with six optimization corridors and 19 nodes critical for cross-domain connectivity.Watershed units emphasize natu-ral integrity and cross-boundary connections,while administrative units ensure adaptability and operational feasibil-ity.Combining both approaches enhances cross-boundary coordination.This study proposes an"Overlay retention-key infil-global integration"framework for multi-scale ecological network optimization.This framework provides a methodological reference for balancing ecological security and urban development in water-rich cities,offering action-able insights for similar regions. 展开更多
关键词 Multilevel ecological networks Watershed units Cross-domain synergies Magnitude effects Nested indices
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Spatiotemporal variation and driving mechanisms of nest predation on Spotted Doves along an urbanization gradient 认领 引用
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作者 Qingxin Fang Wanyou Li +4 位作者 Junpeng Bai Fengxi Hu Zhen Zhang Long Ma Luzhang Ruan 《Avian Research》 SCIE CAS CSCD 2026年第1期22-34,共13页
Nest predation is a critical driver of avian reproductive success,yet its response to urbanization remains controversial.Using infrared camera traps to monitor 133 artificial nests and 32 natural nests of the Spotted ... Nest predation is a critical driver of avian reproductive success,yet its response to urbanization remains controversial.Using infrared camera traps to monitor 133 artificial nests and 32 natural nests of the Spotted Dove(Spilopelia chinensis) along an urbanization gradient in Nanchang and Shangrao,China,from 2021 to 2023,we examined spatiotemporal variation in predation pressure.We deconstructed predation pressure into risk(nest fate and survival time) and pattern(predation frequency,predator size,and predator-nest interaction duration).We found that higher urbanization and better nest concealment significantly reduced predation risk.The composition of the predator community did not change along the urbanization gradient,suggesting that the reduced nest predation risk in cities is likely driven by behavioral factors,such as the availability of alternative food or human shield effect,rather than by the filtering of predator species.In contrast,predation patterns were primarily moderated by season.The off-peak breeding season was char acterized by more frequent but less severe predation events involving smaller predators and had shorter predator-nest interaction durations compared to the peak season.This seasonal shift opens a breeding window during the off-peak season,when lethal nest predation risk is reduced.The Spotted Dove's unique life-history traits enable it to capitalize on this opportunity by balancing environmental costs,enhancing its reproductive success and facilitating its colonization of urban environments. 展开更多
关键词 Artificial nest Camera trapping Life-history trade-offs Predator community Seasonal dynamics
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NestLipGNN:A Hierarchical Graph Neural Network Framework with Nested Multi-Granularity Learning for Robust Visual Speech Recognition 认领 引用
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作者 Vinh Truong Hoang Nghia Dinh +5 位作者 Luu Quang Phuong Kiet Tran-Trung Ha Duong Thi Hong Bay Nguyen Van Hau Nguyen Trung Thien Ho Huong 《Computers, Materials & Continua》 SCIE EI 2026年第7期1287-1310,共24页
Visual speech recognition(VSR)aims to infer spoken content from visual observations of articulatory movements.Despite significant progress,it remains a challenging task in computer vision and speech processing.Its dif... Visual speech recognition(VSR)aims to infer spoken content from visual observations of articulatory movements.Despite significant progress,it remains a challenging task in computer vision and speech processing.Its difficulty arises from pronounced speaker-to-speaker variability,the presence of homophenes(phonemes that are visually indistinguishable),changes in illumination,and the intrinsically high-dimensional nature of spatiotemporal lip dynamics.In this work,we propose NestLipGNN,a graph-based framework that integrates Graph Neural Networks(GNNs)with a nested multi-granularity learning strategy for visual speech recognition.We construct dynamic lip graphs from facial landmarks to model both spatial relationships between lip regions and their temporal motion during speech articulation.The proposed nested learning architecture supports hierarchical feature extraction across several levels of linguistic abstraction,spanning phoneme-level articulatory units,viseme-level visual speech categories,and word-level semantic representations.We further introduce a Temporal Graph Attention mechanism(T-GAT)that adaptively reweights the importance of distinct lip regions over time.We also introduce a graph-based contrastive learning objective to improve the discrimination of visually similar speech patterns,directly confronting the challenge of homophene resolution.Experiments on the LRW,LRS2,LRS3,and GRID datasets show that NestLipGNN improves recognition accuracy compared with existing methods,obtaining 92.3%word-level accuracy on LRW and delivering a 2.1%absolute performance gain over prior methods.Comprehensive ablation analyses confirm the contribution of each architectural component. 展开更多
关键词 Visual speech recognition graph neural networks nested optimization hierarchical representation learning spatiotemporal modeling contrastive learning lip reading
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Nesting season,nest age,and disturbance,but not habitat characteristics,affect nest survival of Chinese grouse 认领 引用 被引量：6
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作者 Jin-Ming ZHAO Chen YANG +3 位作者 Ying-Qiang LOU Mei SHI Yun FANG Yue-Hua SUN 《Current Zoology》 SCIE CAS CSCD 2020年第1期29-37,共9页
Nest survival is a vital component of breeding success,and affects population dynamics,as the loss of nests is the main cause of reproductive failure in birds.To identify key factors for the conservation of Chinese gr... Nest survival is a vital component of breeding success,and affects population dynamics,as the loss of nests is the main cause of reproductive failure in birds.To identify key factors for the conservation of Chinese grouse Tetrastes sewerzowi,we tested the effects of nest concealment,nest age,nesting season,and habitat edge on nest daily survival rate(DSR)of Chinese grouse using 54 nests found at Lianhuashan Nature Reserve,Gansu,China,2009-2012.Moreover,we controlled for the effect of research activity by testing the effect of nest checks on DSR.Overall,mammal predation caused 93%of nest failures.DSR was 0.986±0.0038 in the constant model and the probability of a nest with a full clutch of 6 eggs surviving the entire 40-day nesting period was 0.526±0.090.DSR decreased with nest age and nesting season(from 19 May to 3 July).Mammals instead of avian predators being responsible for most nest failures suggest that nest sites might be selected to avoid visual avian predators,but not olfactory mammalian predators,and the decreasing trend of DSR with nest age and nesting season could attribute to an additive exposure effect.Moreover,nest checks conducted by investigators significantly lowered nest DSR,especially during the late period of nesting season and for older nests.Mammalian predators might locate the nest site by following the investigator's odor.Based on our results,we suggest that the late incubation stage is a particularly vulnerable period for nest survival of Chinese grouse and those researchers should adjust their activities around nests to balance the need of acquiring accurate data and decreasing nest predation risk. 展开更多
关键词 nest age nest check nesting season nest survival program MARK Tetrastes sewerzowi
基于混合Nested Logit模型的用户需求估计 认领 引用
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作者 罗陈斌 薛巍立 张莲民 《管理工程学报》 CSSCI CSCD 北大核心 2026年第2期270-283,共14页
收益管理中,估计用户需求是产品品类管理、产品定价等后续优化工作的首要任务。准确地对用户的选择行为进行刻画和建模,可以帮助企业提升运营管理决策效果。在线零售环境下,用户的产品点击、购买、离开等行为都会被准确地记录下来。然而... 收益管理中,估计用户需求是产品品类管理、产品定价等后续优化工作的首要任务。准确地对用户的选择行为进行刻画和建模,可以帮助企业提升运营管理决策效果。在线零售环境下,用户的产品点击、购买、离开等行为都会被准确地记录下来。然而,很少有研究对用户购买前的离散行为进行刻画。并且,现有方法多使用单一模型分析所有用户的选择,忽略了用户选择行为的异质性。因此,本文提出混合Nested Logit模型,在考虑用户异质性的基础上,对用户两阶段选择行为进行刻画,将用户分类和类内选择构建在同一框架内。为同时估计选择模型参数并识别用户类型,本文使用EM算法求解模型参数。结果显示,EM算法能有效提升估计效率,并且保证结果的收敛性。本文使用京东移动应用程序(App)的零售数据进行实证研究。结果显示,在数据稀疏程度较高的情况下,本文模型的预测准确度平均比基准模型高13.71%,说明考虑用户异质性和多阶段选择能更准确地刻画用户选择行为;进一步将需求估计结果应用于产品品类管理策略制定上,结果显示,本文模型生成的产品品类所带来的收益平均比基准模型高5.11%,这进一步说明,在线环境中不准确的用户行为刻画会导致次优的运营决策。 展开更多
关键词 离散选择模型 混合Nested Logit模型 需求估计 EM算法
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Anthropogenic nesting materials and reproductive performance of Chinese Bulbuls(Pycnonotus sinensis)along the urbanization gradient in Hangzhou,China 认领 引用 被引量：8
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作者 Xingmin Chen Qin Zhang +3 位作者 Sisi Lan Qin Huang Shuihua Chen Yanping Wang 《Avian Research》 SCIE CSCD 2024年第4期431-437,共7页
Urbanization induced by human activities presents both challenges and adaptive opportunities for wildlife.One notable impact of urban sprawl is the vast amount of waste it produces,which has discernible effects on wil... Urbanization induced by human activities presents both challenges and adaptive opportunities for wildlife.One notable impact of urban sprawl is the vast amount of waste it produces,which has discernible effects on wildlife.Interestingly,an emerging trend has been observed that birds are incorporating anthropogenic materials into their nests.However,the relationship between anthropogenic nesting materials(ANMs)and the reproductive performance of urban birds is unclear.In this study,we investigated the relationship between the incorporation of ANMs into nests and the reproductive performance of Chinese Bulbuls(Pycnonotus sinensis)by monitoring and collecting data on 136 breeding nests in Hangzhou,China.We gathered data on seven reproductive traits of Chinese Bulbuls,including laying date,incubation period,nestling period,clutch size,egg volume,hatching success rate,and fledging success rate.We then calculated the urbanization synthetic index as a measure of the level of urbanization and examined its relationship with the proportion and weight of ANMs.Through examination of nest components,we observed significant increase in the proportion and weight of ANMs with the urbanization synthetic index.Notably,we found a higher hatching success rate of Chinese Bulbuls with an increasing proportion of ANMs.However,the inclusion of ANMs in nests was not correlated with other reproductive traits of Chinese Bulbuls.Overall,the use of ANMs by Chinese Bulbuls is consistent with the adaptive hypothesis and the availability hypothesis.Further studies should use controlled experiments to investigate the impact of ANMs on avian reproductive success. 展开更多
关键词 Adaptive hypothesis Anthropogenic nesting materials Availability hypothesis Hatching success Reproductive traits Urbanization
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Influences of muzzle jets of aircraft guns on aerodynamic performance of wings 认领 引用
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作者 Zijie Li Hao Wang 《Defence Technology（防务技术）》 SCIE EI CAS CSCD 2026年第1期52-63,共12页
The core components of an aircraft and the source of its lift are its wings,but lift generation is disrupted by the high temperature and pressure generated on the wing surface when an aircraft gun is fired.Here,to inv... The core components of an aircraft and the source of its lift are its wings,but lift generation is disrupted by the high temperature and pressure generated on the wing surface when an aircraft gun is fired.Here,to investigate how this process influences the aerodynamic parameters of aircraft wings,the k-ωshearstress-transport turbulence model and the nested dynamic grid technique are used to analyze numerically the transient process of the muzzle jet of a 30-mm small-caliber aircraft gun in highaltitude(10 km)flight with an incoming Mach number of Ma=0.8.For comparison,two other models are established,one with no projectile and the other with no wing.The results indicate that when the aircraft gun is fired,the muzzle jet acts on the wing,creating a pressure field thereon.The uneven distribution of high pressure greatly reduces the lift of the aircraft,causing oscillations in its drag and disrupting its dynamic balance,thereby affecting its flight speed and attitude.Meanwhile,the muzzle jet is obstructed by the wing,and its flow field is distorted and deformed,developing upward toward the wing.Because of the influence of the incoming flow,the shockwave front of the projectile changes from a smooth spherical shape to an irregular one,and the motion parameters of the projectile are also greatly affected by oscillations.The present results provide an important theoretical basis for how the guns of fighter aircraft influence the aerodynamic performance of the wings. 展开更多
关键词 Aircraft gun Wing Muzzle jet Aerodynamic performance Nested moving mesh
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Common blackbirds Turdus merula use anthropogenic structures as nesting sites in an urbanized landscape 认领 引用 被引量：9
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作者 YanDingWANG Qin HUANG +2 位作者 Sisi LAN Qin ZHANG Shuihua CHEN 《Current Zoology》 SCIE CAS CSCD 2015年第3期435-443,共9页
The common blackbird Turdus merula is one of the most highly urbanized bird species. However, to date, the use of anthropogenic structures as nesting sites in the common blackbird is rarely documented, and the factors... The common blackbird Turdus merula is one of the most highly urbanized bird species. However, to date, the use of anthropogenic structures as nesting sites in the common blackbird is rarely documented, and the factors influencing its use of the anthropogenic structures as nesting sites remain unclear. In this study, we systematically quantified and determined the factors in- fluencing the use of anthropogenie structures as nesting sites in common blackbirds in a highly urbanized city of Hangzhou, Chi- na. We searched for nests of common blackbirds during four breeding seasons from 2010 to 2013. Among the 60 nests found, 34 nests were in anthropogenic structures such as wall ledges, air condition mounts, window canopies, cable poles, guardrails, eaves, balcony frames, flowerpots and flower shelves on balconies. We found that the available anthropogenic nest sites and the availa- ble nesting trees were main factors determining the use of anthropogenic structures as nesting sites in common blackbirds. In ur- ban environments, the amount of available anthropogenic nesting sites increased significantly, whereas the number of natural nesting sites reduced greatly. Our results suggest that common blackbirds can adjust their nest sites in response to urbanization and such nesting behavior shifts may aid them to colonize urban environments. From a management viewpoint, our results indi- cate that behavioral flexibility should be taken into account for effective urban wildlife management and conservation 展开更多
关键词 Adaptation Anthropogenic nest Behavioral flexibility Colonization Urbanization
Does nest sanitation elicit egg rejection in an open-cup nesting cuckoo host rejecter? 认领 引用 被引量：5
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作者 Tongping Su Chanchao Yang +1 位作者 Shuihua Chen Wei Liang 《Avian Research》 SCIE CSCD 2018年第4期294-298,共5页
Background: Nest sanitation behavior is one of the most important means to ensure high reproductive efficiency. In avian brood parasitism, nest sanitation behavior may be a pre-adaptation of host birds that allows the... Background: Nest sanitation behavior is one of the most important means to ensure high reproductive efficiency. In avian brood parasitism, nest sanitation behavior may be a pre-adaptation of host birds that allows them to identify the parasitic eggs, so that egg discrimination behavior may have evolved from nest sanitation behavior. However, whether nest sanitation behavior could improve egg rejection in cuckoo hosts was inconclusive.Methods: In this study, we investigated the relationship between nest sanitation and egg discrimination behavior in a potential cuckoo host, the Brown-breasted Bulbul(Pycnonotus xanthorrhous) with two experimental groups. In the first group, we added a blue, non-mimetic egg to the nest of the host, while in the second group we added a blue, non-mimetic egg and a peanut half-shell.Results: The results showed that in the first group, the probability of rejecting the non-mimetic eggs was 53.8%(n = 26 nests). In comparison, all of the Brown-breasted Bulbuls in the second group were able to rapidly remove the peanut shells from the nest, but only 52.6%(n = 19 nests) rejected the non-mimetic eggs. The rejection rates of the non-mimetic eggs in both experimental groups were not significantly different.Conclusions: Our study indicated that nest sanitation behavior of Brown-breasted Bulbuls did not influence their egg recognition and that egg discrimination ability of Brown-breasted Bulbuls was not directly related to nest sanitation behavior. 展开更多
关键词 Brood parasitism Brown-breasted Bulbul Egg discrimination Nest sanitation behavior Cuckoo host
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机器人型钢等离子/激光切割生产线设计及关键技术分析 认领 引用
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作者 汪永刚 于浩楠 +4 位作者 李乃健 熊斌 王智新 高健 王凯旋 《焊接》 2026年第1期66-75,共10页
【目的】针对传统型钢切割工艺效率低下、精度不足等问题,文中设计了一种机器人型钢自动切割生产线,并对其关键技术进行了深入研究。【方法】该生产线采用等离子切割工艺,兼具激光切割功能,能够实现型钢的快速切断、开孔划线、端部坡口... 【目的】针对传统型钢切割工艺效率低下、精度不足等问题,文中设计了一种机器人型钢自动切割生产线,并对其关键技术进行了深入研究。【方法】该生产线采用等离子切割工艺,兼具激光切割功能,能够实现型钢的快速切断、开孔划线、端部坡口切割等多种加工任务,并具备自动喷印划线功能。生产线通过多个功能单元的协同作业,实现了从上料、输送、夹持、切割到出料的全流程自动化。系统设计中引入了激光检测装置,能够对原材料的变形进行三维检测,并自动修正切割轨迹,确保加工精度。此外,通过三维型材套料软件和机器人参数标定与补偿技术,进一步优化了切割路径和机器人运动精度。【结果】试验结果表明,该生产线在切割效率和精度方面均满足技术要求,能够高效完成多种规格型钢的切割任务,具有良好的运动平稳性和广泛的型材兼容性。【结论】该研究为海洋工程、钢结构建筑等领域型钢加工的智能化提供了技术支持,具有重要的现实意义。 展开更多
关键词 等离子/激光切割 机器人型钢切割生产线 激光检测 Shape Nest套料软件 近净成形精密切割
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