期刊文献+
共找到439篇文章
< 1 2 22 >
每页显示 20 50 100
Framework system and research flow of uncertainty in 3D geological structure models 被引量:7
1
作者 ZHU, Liangfeng ZHUANG, Zhiyi 《Mining Science and Technology》 EI CAS 2010年第2期306-311,共6页
Uncertainty in 3D geological structure models has become a bottleneck that restricts the development and application of 3D geological modeling.In order to solve this problem during periods of accuracy assessment,error... Uncertainty in 3D geological structure models has become a bottleneck that restricts the development and application of 3D geological modeling.In order to solve this problem during periods of accuracy assessment,error detection and dynamic correction in 3D geological structure models,we have reviewed the current situation and development trends in 3D geological modeling.The main context of uncertainty in 3D geological structure models is discussed.Major research issues and a general framework system of uncertainty in 3D geological structure models are proposed.We have described in detail the integration of development practices of 3D geological modeling systems,as well as the implementation process for uncertainty evaluation in 3D geological structure models.This study has laid the basis to build theoretical and methodological systems for accuracy assessment and error correction in 3D geological models and can assist in improving 3D modeling techniques under complex geological conditions. 展开更多
关键词 3D geological structure model model quality UNCERTAINTY 3D geological modeling
在线阅读 下载PDF
Deciphering environmental factors influencing phytoplankton community structure in a polluted urban river 被引量:2
2
作者 Xiaxia Li Kai Chen +7 位作者 Chao Wang Tianyu Zhuo Hongtao Li Yong Wu Xiaohui Lei Ming Li Bin Chen Beibei Chai 《Journal of Environmental Sciences》 2025年第2期375-386,共12页
Tuojiang River Basin is a first-class tributary of the upper reaches of the Yangtze River—which is the longest river in China.As phytoplankton are sensitive indicators of trophic changes inwater bodies,characterizing... Tuojiang River Basin is a first-class tributary of the upper reaches of the Yangtze River—which is the longest river in China.As phytoplankton are sensitive indicators of trophic changes inwater bodies,characterizing phytoplankton communities and their growth influencing factors in polluted urban rivers can provide new ideas for pollution control.Here,we used direct microscopic count and environmental DNA(eDNA)metabarcoding methods to investigate phytoplankton community structure in Tuojiang River Basin(Chengdu,Sichuan Province,China).The association between phytoplankton community structure and water environmental factors was evaluated by Mantel analysis.Additional environmental monitoring data were used to pinpoint major factors that influenced phytoplankton growth based on structural equation modeling.At the phylum level,the dominant phytoplankton taxa identified by the conventional microscopic method mainly belonged to Bacillariophyta,Chlorophyta,and Cyanophyta,in contrast with Chlorophyta,Dinophyceae,and Bacillariophyta identified by eDNA metabarcoding.Inα-diversity analysis,eDNA metabarcoding detected greater species diversity and achieved higher precision than the microscopic method.Phytoplankton growth was largely limited by phosphorus based on the nitrogen-to-phosphorus ratios>16:1 in all water samples.Redundancy analysis and structural equation modeling also confirmed that the nitrogen-to-phosphorus ratio was the principal factor influencing phytoplankton growth.The results could be useful for implementing comprehensive management of the river basin environment.It is recommended to control the discharge of point-and surface-source pollutants and the concentration of dissolved oxygen in areas with excessive nutrients(e.g.,Jianyang-Ziyang).Algae monitoring techniques and removal strategies should be improved in 201 Hospital,Hongrihe Bridge and Colmar Town areas. 展开更多
关键词 Environmental DNA Microscopic count Phytoplankton growth Structural equation modeling Tuojiang River Basin
原文传递
Evaluation of three-dimensional structure modeling of key enzymes in endogenous catabolism of polyamines
3
作者 GUO Baolin XUE Qian +1 位作者 WANG Bing ZHAO Yuan 《化学研究》 2025年第3期268-277,共10页
The acetylpolyamine oxidase(APAO),spermine oxidase(SMO),and spermidine/spermine N1-acetyltransferase(SSAT)are pivotal enzymes in polyamine metabolism,exerting direct influence on polyamine homeostasis regulation.Dysfu... The acetylpolyamine oxidase(APAO),spermine oxidase(SMO),and spermidine/spermine N1-acetyltransferase(SSAT)are pivotal enzymes in polyamine metabolism,exerting direct influence on polyamine homeostasis regulation.Dysfunctions in these enzymes are intricately linked to inflammatory diseases and cancers.Establishing their three-dimensional structures is essential for exploring enzymatic catalytic mechanisms and designing inhibitors at the atomic level.This article primarily assesses the precision of AlphaFold2 and molecular dynamics simulations in determining the three-dimensional structures of these enzymes,utilizing protein conformation rationality assessment,residue correlation matrix,and other techniques.This provides robust models for subsequent polyamine catabolic metabolism calculations and offers valuable insights for modeling proteins that have yet to acquire crystal structures. 展开更多
关键词 AlphaFold2 molecular dynamics simulation polyamine metabolism ENZYME structure modeling
在线阅读 下载PDF
Anomaly Models of Spatial Structures for Copper-Molybdenum Ore Deposits and their Application 被引量:11
4
作者 MA Shengming ZHU Lixin +2 位作者 LIU Chongmin XI Mingjie TANG Shixin 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2013年第3期843-857,共15页
This paper discusses the enrichment and depletion regularities for porphyry coppermolybdenum ore deposits in different regions and varied deposit genetic types in the same area, taking three porphyry copper-molybdenum... This paper discusses the enrichment and depletion regularities for porphyry coppermolybdenum ore deposits in different regions and varied deposit genetic types in the same area, taking three porphyry copper-molybdenum ore deposits (i.e., the Chengmenshan in Jiangxi, Wunugetushan in Inner Mongolia, Baishantang in Gansu) and two copper deposits in Gansu Province (the Huitongshan skarn deposit and Gongpoquan composite deposit) as case studies. The results show that porphyry Cu-Mo deposits or skarn copper deposits include both enrichment of the ore-forming elements and associated elements, and depletion of some lithophile dispersed elements, rare earth elements (REE) and some major elements. And the depleted elements vary with deposits, having generality and their own features. On a deposit scale, the positive anomalies of enriched elements and negative anomalies of depleted elements follow in a sequence to comprise regular anomaly models of spatial structures. The exploration in the Tongchang deposit in Jiangxi and Huitongshan deposit in Gansu suggests that anomaly models play a key role in the identification of mineral occurrences and deposits compared to one single enriched element anomaly. And the anomaly models exert a critical effect on the optimization of prospecting targets and their potential evaluation. 展开更多
关键词 copper-molybdenum deposits enrichment and depletion anomaly models of spatial structures case studies
在线阅读 下载PDF
Drivers of spatial structure in thinned forests 被引量:1
5
作者 Zichun Wang Yaoxiang Li +4 位作者 Guangyu Wang Zheyu Zhang Ya Chen Xiaoli Liu Rundong Peng 《Forest Ecosystems》 SCIE CSCD 2024年第2期202-213,共12页
Background:As is widely known,an increasing number of forest areas were managed to preserve and enhance the health of forest ecosystems.However,previous research on forest management has often overlooked the importanc... Background:As is widely known,an increasing number of forest areas were managed to preserve and enhance the health of forest ecosystems.However,previous research on forest management has often overlooked the importance of structure-based.Aims:Our objectives were to define the direction of structure-based forest management.Subsequently,we investigated the relationships between forest structure and the regeneration,growth,and mortality of trees under different thinning treatments.Ultimately,the drivers of forest structural change were explored.Methods:On the basis of 92 sites selected from northeastern China,with different recovery time (from 1 to 15years) and different thinning intensities (0–59.9%) since the last thinning.Principal component analysis (PCA)identified relationships among factors determining forest spatial structure.The structural equation model (SEM)was used to analyze the driving factors behind the changes in forest spatial structure after thinning.Results:Light thinning (0–20%trees removed) promoted forest regeneration,and heavy thinning (over 35% of trees removed) facilitated forest growth.However,only moderate thinning (20%–35%trees removed) created a reasonable spatial structure.While dead trees were clustered,and they were hardly affected by thinning intensity.Additionally,thinning intensity,recovery time,and altitude indirectly improve the spatial structure of the forest by influencing diameter at breast height (DBH) and canopy area.Conclusion:Creating larger DBH and canopy area through thinning will promote the formation of complex forest structures,which cultivates healthy and stable forests. 展开更多
关键词 THINNING Natural secondary forest Spatial structure Dynamic changes Growth factors Structural equation modeling
在线阅读 下载PDF
Intensive management enhances mycorrhizal respiration but decreases free-living microbial respiration by affecting microbial abundance and community structure in Moso bamboo forest soils 被引量:1
6
作者 Wenhao JIN Jiangfei GE +6 位作者 Shuai SHAO Liyuan PENG Jiajia XING Chenfei LIANG Junhui CHEN Qiufang XU Hua QIN 《Pedosphere》 SCIE CAS CSCD 2024年第2期508-519,共12页
Intensive management is known to markedly alter soil carbon(C)storage and turnover in Moso bamboo forests compared with extensive management.However,the effects of intensive management on soil respiration(RS)component... Intensive management is known to markedly alter soil carbon(C)storage and turnover in Moso bamboo forests compared with extensive management.However,the effects of intensive management on soil respiration(RS)components remain unclear.This study aimed to evaluate the changes in different RScomponents(root,mycorrhizal,and free-living microorganism respiration)in Moso bamboo forests under extensive and intensive management practices.A1-year in-situ microcosm experiment was conducted to quantify the RScomponents in Moso bamboo forests under the two management practices using mesh screens of varying sizes.The results showed that the total RSand its components exhibited similar seasonal variability between the two management practices.Compared with extensive management,intensive management significantly increased cumulative respiration from mycorrhizal fungi by 36.73%,while decreased cumulative respiration from free-living soil microorganisms by 8.97%.Moreover,the abundance of arbuscular mycorrhizal fungi(AMF)increased by 43.38%,but bacterial and fungal abundances decreased by 21.65%and 33.30%,respectively,under intensive management.Both management practices significantly changed the bacterial community composition,which could be mainly explained by soil pH and available potassium.Mycorrhizal fungi and intensive management affected the interrelationships between bacterial members.Structural equation modeling indicated that intensive management changed the cumulative RSby elevating AMF abundance and lowering bacterial abundance.We concluded that intensive management reduced the microbial respiration-derived C loss,but increased mycorrhizal respiration-derived C loss. 展开更多
关键词 arbuscular mycorrhizal fungi extensive management microbial co-occurrence network root respiration soil organic C soil respiration structural equation model
原文传递
Modeling and petrophysical properties of digital rock models with various pore structure types: An improved workflow
7
作者 Xiaobin Li Wei Wei +2 位作者 Yuxuan Xia Lei Wang Jianchao Cai 《International Journal of Coal Science & Technology》 EI CAS CSCD 2023年第5期38-56,共19页
Pore structure is a crucial factor affecting the physical properties of porous materials,and understanding the mechanisms and laws of these effects is of great significance in the fields of geosciences and petroleum e... Pore structure is a crucial factor affecting the physical properties of porous materials,and understanding the mechanisms and laws of these effects is of great significance in the fields of geosciences and petroleum engineering.However,it remains a challenge to accurately understand and quantify the relationship between pore structures and effective properties.This paper improves a workflow to focus on investigating the effect of pore structure on physical properties.First,a hybrid modeling approach combining process-based and morphology-based methods is proposed to reconstruct 3D models with diverse pore structure types.Then,the characteristics and differences in pore structure in these models are compared.Finally,the varia-tion laws and pore-scale mechanisms of the influence of pore structure on physical properties(permeability and elasticity)are discussed based on the reconstructed models.The relationship models between pore structure parameters and perme-ability/elastic parameters in the grain packing model are established.The effect of pore structure evolution on permeability/elasticity and the microscopic mechanism in three types of morphology-based reconstruction models are explored.The influence degree of pore structure on elastic parameters(bulk modulus,shear modulus,P-wave velocity,and S-wave veloc-ity)is quantified,reaching 29.54%,51.40%,18.94%,and 23.18%,respectively.This work forms a workflow for exploring the relationship between pore structures and petrophysical properties at the microscopic scale,providing more ideas and references for understanding the complex physical properties in porous media. 展开更多
关键词 Hybrid modeling Pore structure Petrophysical properties Microscopic mechanism
在线阅读 下载PDF
Three-dimensional structural models,evolution and petroleum geological significances of transtensional faults in the Ziyang area,central Sichuan Basin,SW China
8
作者 TIAN Fanglei GUO Tonglou +6 位作者 HE Dengfa GU Zhanyu MENG Xianwu WANG Renfu WANG Ying ZHANG Weikang LU Guo 《Petroleum Exploration and Development》 SCIE 2024年第3期604-620,共17页
With drilling and seismic data of Transtensional(strike-slip)Fault System in the Ziyang area of the central Sichuan Basin,SW China plane-section integrated structural interpretation,3-D fault framework model building,... With drilling and seismic data of Transtensional(strike-slip)Fault System in the Ziyang area of the central Sichuan Basin,SW China plane-section integrated structural interpretation,3-D fault framework model building,fault throw analyzing,and balanced profile restoration,it is pointed out that the transtensional fault system in the Ziyang 3-D seismic survey consists of the northeast-trending F_(I)19 and F_(I)20 fault zones dominated by extensional deformation,as well as 3 sets of northwest-trending en echelon normal faults experienced dextral shear deformation.Among them,the F_(I)19 and F_(I)20 fault zones cut through the Neoproterozoic to Lower Triassic Jialingjiang Formation,presenting a 3-D structure of an“S”-shaped ribbon.And before Permian and during the Early Triassic,the F_(I)19 and F_(I)20 fault zones underwent at least two periods of structural superimposition.Besides,the 3 sets of northwest-trending en echelon normal faults are composed of small normal faults arranged in pairs,with opposite dip directions and partially left-stepped arrangement.And before Permian,they had formed almost,restricting the eastward growth and propagation of the F_(I)19 fault zone.The F_(I)19 and F_(I)20 fault zones communicate multiple sets of source rocks and reservoirs from deep to shallow,and the timing of fault activity matches well with oil and gas generation peaks.If there were favorable Cambrian-Triassic sedimentary facies and reservoirs developing on the local anticlinal belts of both sides of the F_(I)19 and F_(I)20 fault zones,the major reservoirs in this area are expected to achieve breakthroughs in oil and gas exploration. 展开更多
关键词 transtensional(strike-slip)fault three-dimensional structural model structural evolution petroleum geological significance Ziyang area Sichuan Basin
在线阅读 下载PDF
Molecular structure characterization of middle-high rank coal via^(13)C NMR,XPS,and FTIR spectroscopy
9
作者 Xiao-ming Ni Jing-shuo Zhang +1 位作者 Xiao-kai Xu Bao-yu Wang 《China Geology》 CAS CSCD 2024年第4期702-713,共12页
Elemental analysis,nuclear magnetic resonance carbon spectroscopy(^(13)C-NMR),X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FTIR)experiments were carried out to determine the existen... Elemental analysis,nuclear magnetic resonance carbon spectroscopy(^(13)C-NMR),X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FTIR)experiments were carried out to determine the existence of aromatic structure,heteroatom structure and fat structure in coal.MS(materials studio)software was used to optimize and construct a 3D molecular structure model of coal.A method for establishing a coal molecular structure model was formed,which was“determination of key structures in coal,construction of planar molecular structure model,and optimization of three-dimensional molecular structure model”.The structural differences were compared and analyzed.The results show that with the increase of coal rank,the dehydrogenation of cycloalkanes in coal is continuously enhanced,and the content of heteroatoms in the aromatic ring decreases.The heteroatoms and branch chains in the coal are reduced,and the structure is more orderly and tight.The stability of the structure is determined by theπ-πinteraction between the aromatic rings in the nonbonding energy EN.Key Stretching Energy The size of EB determines how tight the structure is.The research results provide a method and reference for the study of the molecular structure of medium and high coal ranks. 展开更多
关键词 Molecular structure model Carbon-13 nuclear magnetic resonance(NMR) X-ray photoelectron spectroscopy(XPS) Fourier transform infrared spectroscopy(FTIR) COAL
在线阅读 下载PDF
Evaluating tree branch angle measurements of European beech using terrestrial laser scanning
10
作者 Xi Peng Kim Calders +1 位作者 Louise Terryn Hans Verbeeck 《Forest Ecosystems》 2025年第2期220-230,共11页
Branch angles are an important plant morphological trait affecting light interception within forest canopies.However,studies on branch angles have been limited due to the time-consuming nature of manual measurements u... Branch angles are an important plant morphological trait affecting light interception within forest canopies.However,studies on branch angles have been limited due to the time-consuming nature of manual measurements using a protractor.Terrestrial laser scanning(TLS),however,provides new opportunities to measure branch angles more efficiently.Despite this potential,studies validating branch angle measurements from TLS have been limited.Here,our aim is to evaluate both manual and automatic branch angle measurements of European beech from TLS data using traditional field-measurements with a protractor as a reference.We evaluated the accuracy of branch angle measurements based on four automated algorithms(aRchiQSM,TreeQSM,Laplacian,SemanticLaplacian)from TLS data.Additionally,we assessed different ways of manual branch angle measurements in the field.Our study was based on a dataset comprising 124 branch angles measured from six European beech in a European deciduous forest.Our results show that manual branch angle measurements from TLS data are in high agreement with the reference(root-mean-squared error,RMSE:[3.57°-4.18°],concordance correlation coefficient,CCC:[0.950.97])across different branch length positions.Automated algorithms also are in high agreement with the reference although RMSE is approximately twice as large compared to manual branch angle measurements from TLS(RMSE:[9.29°-10.55°],CCC:[0.830.86])with manual leaf points removal.When applying the automatic wood-leaf separation algorithm,the performance of the four methods declined significantly,with only approximately 20 branch angles successfully identified.Moreover,it is important to note that there is no influence of the measurement position(branch surface versus center)for branch angle measurements.However,for curved branches,the selection of branch measurement length significantly impacts the branch angle measurement.This study provides a comprehensive understanding of branch angle measurements in forests.We show that automated measurement methods based on TLS data of branch angles are a valuable tool to quantify branch angles at larger scales. 展开更多
关键词 Branch angle Measurement methods Quantitative structure models LAPLACIAN Semantic-laplacian Terrestrial laser scanning
在线阅读 下载PDF
Effects of local neighbourhood diversity on crown structure and productivity of individual trees in mature mixed-species forests 被引量:1
11
作者 Louis Georgi Matthias Kunz +4 位作者 Andreas Fichtner Karl Friedrich Reich Anne Bienert Hans-Gerd Maas Goddert von Oheimb 《Forest Ecosystems》 SCIE CSCD 2021年第2期345-356,共12页
Background:Species-specific genotypic features,local neighbourhood interactions and resource supply strongly influence the tree stature and growth rate.In mixed-species forests,diversity-mediated biomass allocation ha... Background:Species-specific genotypic features,local neighbourhood interactions and resource supply strongly influence the tree stature and growth rate.In mixed-species forests,diversity-mediated biomass allocation has been suggested to be a fundamental mechanism underlying the positive biodiversity-productivity relationships.Empirical evidence,however,is rare about the impact of local neighbourhood diversity on tree characteristics analysed at a very high level of detail.To address this issue we analysed these effects on the individual-tree crown architecture and tree productivity in a mature mixed forest in northern Germany.Methods:Our analysis considers multiple target tree species across a local neighbourhood species richness gradient ranging from 1 to 4.We applied terrestrial laser scanning to quantify a large number of individual mature trees(N=920)at very high accuracy.We evaluated two different neighbour inclusion approaches by analysing both a fixed radius selection procedure and a selection based on overlapping crowns.Results and conclusions:We show that local neighbourhood species diversity significantly increases crown dimension and wood volume of target trees.Moreover,we found a size-dependency of diversity effects on tree productivity(basal area and wood volume increment)with positive effects for large-sized trees(diameter at breast height(DBH)>40 cm)and negative effects for small-sized(DBH<40 cm)trees.In our analysis,the neighbour inclusion approach has a significant impact on the outcome.For scientific studies and the validation of growth models we recommend a neighbour selection by overlapping crowns,because this seems to be the relevant scale at which local neighbourhood interactions occur.Because local neighbourhood diversity promotes individual-tree productivity in mature European mixed-species forests,we conclude that a small-scale species mixture should be considered in management plans. 展开更多
关键词 BIODIVERSITY Tree growth Crown architecture Quantitative structure models Terrestrial laser scanning Neighbour classification
在线阅读 下载PDF
The Impact of Chinese Teachers’ Career Calling on Job Burnout: A Dual Path Model of Career Adaptability and Work Engagement 被引量:1
12
作者 Huaruo Chen Wanru Song +3 位作者 Jian Xie Huadi Wang Feifei Zheng Ya Wen 《International Journal of Mental Health Promotion》 2025年第3期379-400,共22页
Objectives:Teachers are facing unprecedented new challenges leading them to face an increasing number of tasks that are not part of their job,as well as having to cope with the additional skills acquisition that comes... Objectives:Teachers are facing unprecedented new challenges leading them to face an increasing number of tasks that are not part of their job,as well as having to cope with the additional skills acquisition that comes with non-traditional forms of teaching and learning,and increased work pressure leading to an increase in the rate of teachers leaving the profession.Therefore,this study aims to explore the mechanism of the career calling on job burnout through career adaptability and work engagement.Methods:This study conducted a cross-sectional survey of 465 primary and secondary school teachers(PSST)in China's Mainland from the perspective of work adjustment and used structural equation modeling(SEM)to examine the mediating roles of career adaptability and work engagement in the relationship between teachers’career calling and job burnout.Results:The results show that PSSTs are above average in career calling,career adaptability,and work engagement,while job burnout is below average.A significant positive or negative correlation exists between career calling,career adaptability,work engagement,and job burnout.The result of path analysis indicates that career adaptability and work engagement exert an indirect influence on the job burnout of PSST through three paths:namely,the independent intermediary role of career adaptability(EV=−0.144),the independent intermediary role of work engagement(EV=0.172)and the chain intermediary role of the two(EV=0.176).Conclusion:This study emphasizes the importance of career adaptability and work engagement in teacher development in regulating career calling and job burnout.Therefore,on the one hand,we think that if managers want to reduce teachers’job burnout,they need to pay more attention to teachers’career adaptability and work engagement,rather than relying solely on teachers’career calling.On the other hand,it is to remind teachers not to rely on their adjustment to adapt to the work,but also to need outside help as much as possible. 展开更多
关键词 Career calling job burnout career adaptability work engagement structural equation model(SEM)
在线阅读 下载PDF
Influence pathways of vanadium stress to microbial community in soil-tailings-groundwater systems 被引量:1
13
作者 Dan Zhou Yonglian Xia +2 位作者 Chao Li Mingzheng Huang Yi Huang 《Journal of Environmental Sciences》 2025年第8期264-276,共13页
The large-scale exploitation of vanadium(Ⅴ) bearing minerals has led to a massive accumulation of Ⅴ tailings, of which Ⅴ pollution poses severe ecological risks. Although the mechanisms of Ⅴ stress to the microbia... The large-scale exploitation of vanadium(Ⅴ) bearing minerals has led to a massive accumulation of Ⅴ tailings, of which Ⅴ pollution poses severe ecological risks. Although the mechanisms of Ⅴ stress to the microbial community have been reported, the influential pathways in a multi-medium-containing system, for example, the soil-tailings-groundwater system,are unknown. The dynamic redox conditions and substance exchange within the system exhibited complex Ⅴ stress on the local microbial communities. In this study, the influence pathways of Ⅴ stress to the microbial community in the soil-tailings-groundwater system were first investigated. High Ⅴ contents were observed in groundwater(139.2 ± 0.15 μg/L) and soil(98.0–323.8 ± 0.02 mg/kg), respectively. Distinct microbial composition was observed for soil and groundwater, where soil showed the highest level of diversity and richness. Firmicutes, Proteobacteria, Actinobacteria, and Acidobacteria were dominant in soil and groundwater with a sum relative abundance of around 80 %. Based on redundancy analysis and structural equation models, Ⅴ was one of the vital driving factors affecting microbial communities. Groundwater microbial communities were influenced by Ⅴ via Cr, dissolved oxygen, and total nitrogen, while Fe, Mn, and total phosphorus were the key mediators for Ⅴ to affect soil microbial communities. Ⅴ affected the microbial community via metabolic pathways related to carbonaceous matter, which was involved in the establishment of survival strategies for metal stress. This study provides novel insights into the influence pathways of Ⅴ on the microorganisms in tailings reservoir for pollution bioremediation. 展开更多
关键词 Vanadium(V)stress Microbial community Structural equation models Influence pathways
原文传递
Model Reference Variable Structure Autopilot Design for Homing Missile 被引量:1
14
作者 宋建梅 《Journal of Beijing Institute of Technology》 EI CAS 2001年第4期364-369,共6页
To design the control system for some homing missile so that the autopilot can transfer guidance command correctly and be robust to disturbances, such as the measurement noises and parameter variation caused by areody... To design the control system for some homing missile so that the autopilot can transfer guidance command correctly and be robust to disturbances, such as the measurement noises and parameter variation caused by areodynamic floating. The model reference adaptive control was combined with the variable structure control to design a model reference variable structure (MRVS) control system whose control structure is simple and can be realized easily. The simulation results indicate that MRVS can complete the task of transferring guidance command and suppress the distrubances effectively. 展开更多
关键词 model reference variable structure variable structure control AUTOPILOT
在线阅读 下载PDF
Research Status of High-Entropy Alloys Based on Artificial Intelligence Technology
15
作者 YU Zhiqi ZHAO Yanchun +5 位作者 XUE Baorui DANG Wenxia MA Huwen SU Yu LAN Yunbo FENG Li 《有色金属(中英文)》 北大核心 2025年第5期735-747,共13页
High-Entropy Alloys(HEAs)exhibit significant potential across multiple domains due to their unique properties.However,conventional research methodologies face limitations in composition design,property prediction,and ... High-Entropy Alloys(HEAs)exhibit significant potential across multiple domains due to their unique properties.However,conventional research methodologies face limitations in composition design,property prediction,and process optimization,characterized by low efficiency and high costs.The integration of Artificial Intelligence(AI)technologies has provided innovative solutions for HEAs research.This review presented a detailed overview of recent advancements in AI applications for structural modeling and mechanical property prediction of HEAs.Furthermore,it discussed the advantages of big data analytics in facilitating alloy composition design and screening,quality control,and defect prediction,as well as the construction and sharing of specialized material databases.The paper also addressed the existing challenges in current AI-driven HEAs research,including issues related to data quality,model interpretability,and cross-domain knowledge integration.Additionally,it proposed prospects for the synergistic development of AI-enhanced computational materials science and experimental validation systems. 展开更多
关键词 high-entropy alloys artificial intelligence structural modeling mechanical property big data
在线阅读 下载PDF
Experimental and analytical investigations of the dynamic characteristics of a mold transformer with rotary friction dampers based on shaking table tests
16
作者 Seung-Jae Lee Ji-Eon Lee +1 位作者 Ngoc Hieu Dinh Kyoung-Kyu Choi 《Earthquake Engineering and Engineering Vibration》 2025年第2期451-472,共22页
In this study, shaking table tests were performed to investigate the dynamic characteristics of a mold transformer. Based on the test results, rotary friction dampers were developed to mitigate the excessive lateral d... In this study, shaking table tests were performed to investigate the dynamic characteristics of a mold transformer. Based on the test results, rotary friction dampers were developed to mitigate the excessive lateral displacement that occurred along the direction of the weak stiffness axis of the mold transformer. In addition, shaking table tests were performed by attaching friction dampers to both sides of the mold transformer. Based on the shaking table test results, the natural frequency, mode vector, and damping ratio of the mold transformer were derived using the transfer function and half-power bandwidth. The test results indicated that the use of friction dampers can decrease the displacement and acceleration response of the mold transformer. Finally, dynamic structural models were established considering the component connectivity and mass distribution of the mold transformer. In addition, a numerical strategy was proposed to calibrate the stiffness coefficients of the mold transformer, thereby facilitating the relationship between generalized mass and stiffness. The results indicated that the analytical model based on the calibration strategy of stiffness coefficients can reasonably simulate the dynamic behavior of the mold transformer using friction dampers with regard to transfer function, displacement, and acceleration response. 展开更多
关键词 mold transformer dynamic characteristics shaking table test rotary friction dampers dynamic structural model stiffness calibration
在线阅读 下载PDF
Analysis of factors infl uencing microseismic detection and location in shale gas extraction areas of western Hubei
17
作者 Hao Wan-peng Zhang Li-fen +3 位作者 Zhao Yan-nan Zheng Rong-ying Qin Wei-bing and Li Jing-gang 《Applied Geophysics》 2025年第2期523-534,561,共13页
The study area is rich in shale gas resources and has reached the stage of comprehensive development. Shale gas extraction poses risks such as induced seismicity and well closure, compounded by the limited availabilit... The study area is rich in shale gas resources and has reached the stage of comprehensive development. Shale gas extraction poses risks such as induced seismicity and well closure, compounded by the limited availability of fi xed seismic monitoring stations nearby. To address these challenges, a dense observation array was developed within the study area to monitor and analyze microseismic activity during hydraulic fracturing. Microseismic events generated by hydraulic fracturing typically exhibit low amplitude and signal-to-noise ratio, rendering traditional manual analysis methods impractical. To overcome these limitations, an innovative artifi cial intelligence method combining picking-association-location (PAL) and match-expand- shift-stack (MESS) techniques (PALM) has been utilized for automated seismic detection. Numerous factors influence the accuracy of microseismic detection and localization. To evaluate these factors, the effects of various velocity structure models, instrument types, and station distributions on seismic location were analyzed and compared. The results indicate that the PALM method significantly mitigates the influence of velocity structure models on seismic location accuracy. Additionally, the use of broadband seismic instruments and a uniform station distribution enhances the precision of seismic location results. Furthermore, by integrating data from diff erent types of observation instruments, a comprehensive seismic catalog for the study area was established. These fi ndings not only enhance seismic location accuracy but also provide valuable guidance for optimizing regional seismic monitoring network design and improving seismic risk assessment. 展开更多
关键词 earthquake location velocity structure model station distribution PALM shale gas
在线阅读 下载PDF
Porosity prediction based on improved structural modeling deep learning method guided by petrophysical information
18
作者 Bo-Cheng Tao Huai-Lai Zhou +3 位作者 Wen-Yue Wu Gan Zhang Bing Liu Xing-Ye Liu 《Petroleum Science》 2025年第6期2325-2338,共14页
Porosity is an important attribute for evaluating the petrophysical properties of reservoirs, and has guiding significance for the exploration and development of oil and gas. The seismic inversion is a key method for ... Porosity is an important attribute for evaluating the petrophysical properties of reservoirs, and has guiding significance for the exploration and development of oil and gas. The seismic inversion is a key method for comprehensively obtaining the porosity. Deep learning methods provide an intelligent approach to suppress the ambiguity of the conventional inversion method. However, under the trace-bytrace inversion strategy, there is a lack of constraints from geological structural information, resulting in poor lateral continuity of prediction results. In addition, the heterogeneity and the sedimentary variability of subsurface media also lead to uncertainty in intelligent prediction. To achieve fine prediction of porosity, we consider the lateral continuity and variability and propose an improved structural modeling deep learning porosity prediction method. First, we combine well data, waveform attributes, and structural information as constraints to model geophysical parameters, constructing a high-quality training dataset with sedimentary facies-controlled significance. Subsequently, we introduce a gated axial attention mechanism to enhance the features of dataset and design a bidirectional closed-loop network system constrained by inversion and forward processes. The constraint coefficient is adaptively adjusted by the petrophysical information contained between the porosity and impedance in the study area. We demonstrate the effectiveness of the adaptive coefficient through numerical experiments.Finally, we compare the performance differences between the proposed method and conventional deep learning methods using data from two study areas. The proposed method achieves better consistency with the logging porosity, demonstrating the superiority of the proposed method. 展开更多
关键词 Porosity prediction Deep learning Improved structural modeling Petrophysical information
原文传递
Impact of perceived severity on depression, anxiety, and insomnia among Chinese community residents during the COVID-19 lockdown
19
作者 Jia-Xi Peng Tian Huang +3 位作者 Lei Wang Yang Yu Jia-Xi Zhang Jin Wang 《World Journal of Psychiatry》 2025年第5期173-183,共11页
BACKGROUND Depression,anxiety,and insomnia were found out that were significant relevance to the mental health impact of the coronavirus disease 2019(COVID-19)lock-down.AIM To examine the interrelationships among perc... BACKGROUND Depression,anxiety,and insomnia were found out that were significant relevance to the mental health impact of the coronavirus disease 2019(COVID-19)lock-down.AIM To examine the interrelationships among perceived severity,anxiety,depression,insomnia,and sense of security in Chinese community residents during the COVID-19 lockdown period.METHODS Participants were selected using simple random sampling from four large gated communities in Chengdu,China.All participants were invited to complete a survey that included the Perceived Severity Questionnaire,Security Question-naire,Patient Health Questionnaire-9,Generalized Anxiety Disorder 7-item,and Insomnia Severity Index-7.In total,568 valid questionnaires were gathered.Co-rrelation analysis and structural equation models were used to explore the rela-RESULTS The observed prevalence rates of anxiety,depression,and insomnia among residents during lockdown were 27.5%,17.6%,and 16.0%,respectively.Correlation analysis showed that both perceived severity and sense of security were positively correlated with anxiety,depression,and insomnia[Pearson’s r was perceived severity and anxiety r=0.44(P<0.01);with depression r=0.48(P<0.01);with insomnia r=0.43(P<0.01);security with anxiety r=-0.65(P<0.01);with depression r=-0.65(P<0.01);with insomnia r=-0.53(P<0.01)].Structural equation modeling and bootstrap tests revealed that sense of security acted as a significant mediator in the relationship between perceived severity and emotional and sleep disorders(anxiety,depression,and insomnia).CONCLUSION This study demonstrates that sense of security is a significant predictor of emotional and sleep disorders(namely,depression,anxiety,and insomnia)among residents during the COVID-19 lockdown,with sense of security acting as a mediating factor.These findings suggest that mental health interventions for Chinese community residents during lockdowns may benefit from developing community-based educational programs to reduce perceived severity and ensuring the stable supply of essential resources and promoting social support networks to enhance the sense of security. 展开更多
关键词 Perceived severity Sense of security DEPRESSION ANXIETY INSOMNIA Structural equation modeling COVID-19
暂未订购
How Labor Values Affect Adolescent Resilience?——Analysis Based on the Perspective of Emotion Regulation Theory
20
作者 Xiaomei Chao Zhuo Yang Yanhui Xiang 《International Journal of Mental Health Promotion》 2025年第4期577-590,共14页
Background:Understanding the factors that influence adolescent psychological resilience is critical for promoting mental health.This study explores the impact and mechanism of labor values on adolescent psychological ... Background:Understanding the factors that influence adolescent psychological resilience is critical for promoting mental health.This study explores the impact and mechanism of labor values on adolescent psychological resilience from the perspective of emotion regulation theory.Methods:This study conducted an in-depth analysis using the Labor Value Scale on 2691 elementary school upper-grade students,middle school students,and high school students.Results:The results show that:(1)labor values can positively predict adolescents’mental resilience;(2)cognitive reappraisal and expression inhibition play a partial mediating role in the relationship between labor values and adolescents’psychological resilience.Among them,labor values can positively predict adolescents’mental resilience through positive cognitive reappraisal,and labor values can also predict adolescents’mental resilience through expression inhibition.Conclusion:Based on the theory of emotion regulation,this study explores the direct effect of labor values on mental resilience and the mediating effect of different strategies of emotion regulation.The results of this study provide a theoretical basis for improving the mental resilience of adolescents. 展开更多
关键词 ADOLESCENT labor values RESILIENCE emotional regulation structural equation model
在线阅读 下载PDF
上一页 1 2 22 下一页 到第
使用帮助 返回顶部