期刊文献+
共找到10,071篇文章
< 1 2 250 >
每页显示 20 50 100
Monitoring Zenithal Total Delays over the three different climatic zones from IGS GPS final products:A comparison between the use of the VMF1 and GMF mapping functions 被引量:4
1
作者 Benachour Labib Jianguo Yan +2 位作者 Jean-Pierre Barriot Fangzhao Zhang Peng Feng 《Geodesy and Geodynamics》 2019年第2期93-99,共7页
The International GNSS Service(IGS) final products(ephemeris and clocks-correction) have made the GNSS an indispensable low-cost tool for scientific research, for example sub-daily atmospheric water vapor monitoring. ... The International GNSS Service(IGS) final products(ephemeris and clocks-correction) have made the GNSS an indispensable low-cost tool for scientific research, for example sub-daily atmospheric water vapor monitoring. In this study, we investigate if there is a systematic difference coming from the choice between the Vienna Mapping Function 1(VMF1) and the Global Mapping Function(GMF) for the modeling of Zenith Total Delay(ZTD) estimates, as well as the Integrated Precipitable Water Vapor(IPWV) estimates that are deduced from them. As ZTD estimates cannot be fully separated from coordinate estimates, we also investigated the coordinate repeatability between subsequent measurements.For this purpose, we monitored twelve GNSS stations on a global scale, for each of the three climatic zones(polar, mid-latitudes and tropical), with four stations on each zone. We used an automated processing based on the Bernese GNSS Software Version 5.2 by applying the Precise Point Positioning(PPP)approach, L3 Ionosphere-free linear combination, 7 cutoff elevation angle and 2 h sampling. We noticed an excellent agreement with the ZTD estimates and coordinate repeatability for all the stations w.r.t to CODE(the Center for Orbit Determination in Europe) and USNO(US Naval Observatory) products, except for the Antarctic station(Davis) which shows systematic biases for the GMF related results. As a final step, we investigated the effect of using two mapping functions(VMF1 and GMF) to estimate the IPWV,w.r.t the IPWV estimates provided by the Integrated Global Radiosonde Archive(IGRA). The GPS-derived IPWV estimates are very close to the radiosonde-derived IPWV estimates, except for one station in the tropics(Tahiti). 展开更多
关键词 International GNSS Service (IGS) VIENNA mapping FUNCTION 1 (VMF1) Global mapping FUNCTION (GMF) Precise Point Positioning (PPP) Zenith TOTAL DELAY (ZTD) Zenith Wet DELAY (ZWD) Integrated Precipitable Water Vapor (IPWV)
原文传递
Mapping theme trends and knowledge structures for human neural stem cells:a quantitative and co-word biclustering analysis for the 2013-2018 period 被引量:5
2
作者 Wen-Juan Wei Bei Shi +3 位作者 Xin Guan Jing-Yun Ma Ya-Chen Wang Jing Liu 《Neural Regeneration Research》 SCIE CAS CSCD 2019年第10期1823-1832,共10页
Neural stem cells,which are capable of multi-potential differentiation and self-renewal,have recently been shown to have clinical potential for repairing central nervous system tissue damage.However,the theme trends a... Neural stem cells,which are capable of multi-potential differentiation and self-renewal,have recently been shown to have clinical potential for repairing central nervous system tissue damage.However,the theme trends and knowledge structures for human neural stem cells have not yet been studied bibliometrically.In this study,we retrieved 2742 articles from the PubMed database from 2013 to 2018 using "Neural Stem Cells" as the retrieval word.Co-word analysis was conducted to statistically quantify the characteristics and popular themes of human neural stem cell-related studies.Bibliographic data matrices were generated with the Bibliographic Item Co-Occurrence Matrix Builder.We identified 78 high-frequency Medical Subject Heading(MeSH)terms.A visual matrix was built with the repeated bisection method in gCLUTO software.A social network analysis network was generated with Ucinet 6.0 software and GraphPad Prism 5 software.The analyses demonstrated that in the 6-year period,hot topics were clustered into five categories.As suggested by the constructed strategic diagram,studies related to cytology and physiology were well-developed,whereas those related to neural stem cell applications,tissue engineering,metabolism and cell signaling,and neural stem cell pathology and virology remained immature.Neural stem cell therapy for stroke and Parkinson’s disease,the genetics of microRNAs and brain neoplasms,as well as neuroprotective agents,Zika virus,Notch receptor,neural crest and embryonic stem cells were identified as emerging hot spots.These undeveloped themes and popular topics are potential points of focus for new studies on human neural stem cells. 展开更多
关键词 nerve REGENERATION human NEURAL stem cells PubMed bibliometric ANALYSIS biclustering ANALYSIS co-word ANALYSIS strategic diagram ANALYSIS social network ANALYSIS hot research topics mapping THEME TRENDS knowledge structures NEURAL REGENERATION
暂未订购
Application of Different Image Processing Techniques on Aster and ETM+ Images for Exploration of Hydrothermal Alteration Associated with Copper Mineralizations Mapping Kehdolan Area (Eastern Azarbaijan Province-Iran) 被引量:2
3
作者 Golchin Hajibapir Mohammad Lotfi +1 位作者 Afshar Zia Zarifi Nima Nezafati 《Open Journal of Geology》 2014年第11期582-597,共16页
The Kehdolan area is located at 20 kilometers to the?south-east of Dozdozan Town (Eastern Azarbaijan Province). According to structural geology, volconic rocks are situated in Alborz-Azarbyjan zone, and faults?are?obs... The Kehdolan area is located at 20 kilometers to the?south-east of Dozdozan Town (Eastern Azarbaijan Province). According to structural geology, volconic rocks are situated in Alborz-Azarbyjan zone, and faults?are?observed?in?the?same direction to this system with SE-NW trend. The results show that kaolinite alteration trend with Argilic and propylitic veins?is the?same direction with SW-NE faults in this area. Therefore, these faults with these trends can be considered as the mineralization control for determination of the alterations. Different image processing techniques,?such as false color composite?(FCC), band ratios, color ratio composite?(CRC), principal component?analysis?(PCA), Crosta technique, supervised spectral angle mapping?(SAM), are used for?identification of the alteration zones associated with copper mineralization. In this project ASTER?data are process and spectral analysis to fit for recognizing intensity and kind of argillic, propylitic,?philic, and ETM+ data?which?are process and to fit for iron oxide and relation to metal mineralization of the area. For recognizing different alterations of the study area, some chemical and mineralogical analysis data from the samples showed that ASTER data and ETM+ data were?capable of hydrothermal alteration mapping with copper mineralization.?Copper mineralization in the region is in agreement with argillic alteration. SW-NE trending faults controlled the mineralization process. 展开更多
关键词 Kehdolan Area False COLOR COMPOSITE Band Ratios COLOR Ratio COMPOSITE Principal Component Analysis Crosta Technique Supervised Spectral Angle mapping ASTER DATA ETM%PLUS% DATA Alteration
暂未订购
A Seismotectonic Zonation Map of Eastern Siberia: New Principles and Methods of Mapping 被引量:1
4
作者 L. P. Imaeva V. S. Imaev +1 位作者 O. P. Smekalin N. N. Grib 《Open Journal of Earthquake Research》 2015年第4期115-125,共11页
The paper reviews goals and objectives, stages and components of a seismotectonic study conducted in Eastern Siberia, Russia. Based on a comprehensive analysis of geological and geophysical data, our study establishes... The paper reviews goals and objectives, stages and components of a seismotectonic study conducted in Eastern Siberia, Russia. Based on a comprehensive analysis of geological and geophysical data, our study establishes whether the local earthquakes are of tectonic origin and reveals relationships among earthquakes with recent geodynamic processes in the area under study. Seismic hazard assessment and evaluation of tectonic processes are the two major closely interrelated aspects of seismotectonic studies. A seismotectonic study is generally combined with a seismic study and conducted prior to the stage of detailed seismic zonation (DSZ) which is followed by seismic micro-zonation (SMZ). In three stages of the seismotectonic study, we analyze specific geological structures, reveal the regional dynamics of seismotectonic processes, clarify details of potential seismic hazard locations and identify sites of the potential instantaneous deformation of the crust which may take place due to active faulting. Based on results of our longterm studies, a seismotectonic zonation map of Eastern Siberia is compiled. The paper briefly reviews the methods of mapping and refers to data on active faults and neotectonic structures revealed in the area under study, which are closely related to regional earthquake sources. 展开更多
关键词 SEISMOTECTONIC Studies SEISMIC Hazard Active Faults Geological and Geomorphological METHODS TRENCHING SEISMIC Source Zones SEISMIC BELTS SEISMIC Belt Segments SEISMOTECTONIC ZONATION Map of Eastern Siberia
在线阅读 下载PDF
Mapping of moraine dammed glacial lakes and assessment of their areal changes in the central and eastern Himalayas using satellite data 被引量:3
5
作者 Sazeda BEGAM Dhrubajyoti SEN 《Journal of Mountain Science》 SCIE CSCD 2019年第1期77-94,共18页
The relatively rapid recession of glaciers in the Himalayas and formation of moraine dammed glacial lakes(MDGLs) in the recent past have increased the risk of glacier lake outburst floods(GLOF) in the countries of Nep... The relatively rapid recession of glaciers in the Himalayas and formation of moraine dammed glacial lakes(MDGLs) in the recent past have increased the risk of glacier lake outburst floods(GLOF) in the countries of Nepal and Bhutan and in the mountainous territory of Sikkim in India. As a product of climate change and global warming, such a risk has not only raised the level of threats to the habitation and infrastructure of the region, but has also contributed to the worsening of the balance of the unique ecosystem that exists in this domain that sustains several of the highest mountain peaks of the world. This study attempts to present an up to date mapping of the MDGLs in the central and eastern Himalayan regions using remote sensing data, with an objective to analyse their surface area variations with time from 1990 through 2015, disaggregated over six episodes. The study also includes the evaluation for susceptibility of MDGLs to GLOF with the least criteria decision analysis(LCDA). Forty two major MDGLs, each having a lake surface area greater than 0.2 km2, that were identified in the Himalayan ranges of Nepal, Bhutan, and Sikkim, have been categorized according to their surface area expansion rates in space and time. The lakes have been identified as located within the elevation range of 3800 m and6800 m above mean sea level(a msl). With a total surface area of 37.9 km2, these MDGLs as a whole were observed to have expanded by an astonishing 43.6% in area over the 25 year period of this study. A factor is introduced to numerically sort the lakes in terms of their relative yearly expansion rates, based on their interpretation of their surface area extents from satellite imageries. Verification of predicted GLOF events in the past using this factor with the limited field data as reported in literature indicates that the present analysis may be considered a sufficiently reliable and rapid technique for assessing the potential bursting susceptibility of the MDGLs. The analysis also indicates that, as of now, there are eight MDGLs in the region which appear to be in highly vulnerable states and have high chances in causing potential GLOF events anytime in the recent future. 展开更多
关键词 GLACIER RETREAT LAKES mapping MORAINE dammed GLACIAL lake(MDGL) Surface area change of LAKES Landsat imagery data Least criteria decision analysis(LCDA)
原文传递
GIS Based Landslide Susceptibility Mapping with Application of Analytical Hierarchy Process in District Ghizer, Gilgit Baltistan Pakistan 被引量:3
6
作者 Irum Rahim Syeda Maria Ali Maria Aslam 《Journal of Geoscience and Environment Protection》 2018年第2期34-49,共16页
District Ghizer is a rugged mountainous territory which experiences several landslides each year. There are 16 major landslide areas and 53 villages that are at high risk to hazards. Keeping in view the severity of na... District Ghizer is a rugged mountainous territory which experiences several landslides each year. There are 16 major landslide areas and 53 villages that are at high risk to hazards. Keeping in view the severity of natural hazards, the present study was designed to generate landslide susceptibility map based on twelve causative factors viz., slope, aspect, elevation, drainage network, Stream Power Index (SPI), Topographic Wetness Index (TWI), lithological units, fault lines, rainfall, road network, land cover and soil texture. Soil texture was determined by particle size analysis and data for other factors were acquired from freely available sources. Analytical Hierarchy Process (AHP) was employed to identify major landslide causative factors in the district Ghizer. Further, a temporal assessment from 1999 till 2015 was generated to assess the impact of land cover change on landslides. It indicated that the barren soil/ exposed rocks and glaciers have reduced while the vegetation and water classes have shown increment. The total area that lies in moderate to very high landslide susceptible zones was 74.38%, while slope is the main landslide causative factor in the district Ghizer. Validation of the susceptibility map showed 88.1% of the landslides in the study area had occurred in the moderate to very high susceptible zones. 展开更多
关键词 LANDSLIDE SUSCEPTIBILITY mapping (LSM) Analytical HIERARCHY Process (AHP) GEOGRAPHIC Information System (GIS) Weighted Linear Combination (WLC) Remote Sensing (RS)
暂未订购
Mapping novel genetic loci associated with female liver weight variations using Collaborative Cross mice 被引量:4
7
作者 Hanifa J.Abu-Toamih Atamni Maya Botzman +2 位作者 Richard Mott Irit Gat-Viks Fuad A.Iraqi 《Animal Models and Experimental Medicine》 2018年第3期212-220,共9页
Background: Liver weight is a complex trait, controlled by polygenic factors and differs within populations. Dissecting the genetic architecture underlying these variations will facilitate the search for key role cand... Background: Liver weight is a complex trait, controlled by polygenic factors and differs within populations. Dissecting the genetic architecture underlying these variations will facilitate the search for key role candidate genes involved directly in the hepatomegaly process and indirectly involved in related diseases etiology.Methods: Liver weight of 506 mice generated from 39 different Collaborative Cross(CC) lines with both sexes at age 20 weeks old was determined using an electronic balance. Genomic DNA of the CC lines was genotyped with high-density single nucleotide polymorphic markers.Results: Statistical analysis revealed a significant(P < 0.05) variation of liver weight between the CC lines, with broad sense heritability(H^2) of 0.32 and genetic coefficient of variation(CV_G) of 0.28. Subsequently, quantitative trait locus(QTL) mapping was performed, and results showed a significant QTL only for females on chromosome 8 at genomic interval 88.61-93.38 Mb(4.77 Mb). Three suggestive QTL were mapped at chromosomes 4, 12 and 13. The four QTL were designated as LWL1-LWL4 referring to liver weight loci 1-4 on chromosomes 8, 4, 12 and 13,respectively.Conclusion: To our knowledge, this report presents, for the first time, the utilization of the CC for mapping QTL associated with baseline liver weight in mice. Our findings demonstrate that liver weight is a complex trait controlled by multiple genetic factors that differ significantly between sexes. 展开更多
关键词 candidate genes COLLABORATIVE CROSS MOUSE model high genetic diverse MOUSE population liver weight quantitative TRAIT locus mapping standard RODENT diet
暂未订购
Mobile Robot Hierarchical Simultaneous Localization and Mapping Using Monocular Vision 被引量:1
8
作者 厉茂海 洪炳熔 罗荣华 《Journal of Shanghai Jiaotong university(Science)》 EI 2007年第6期765-772,共8页
A hierarchical mobile robot simultaneous localization and mapping (SLAM) method that allows us to obtain accurate maps was presented. The local map level is composed of a set of local metric feature maps that are guar... A hierarchical mobile robot simultaneous localization and mapping (SLAM) method that allows us to obtain accurate maps was presented. The local map level is composed of a set of local metric feature maps that are guaranteed to be statistically independent. The global level is a topological graph whose arcs are labeled with the relative location between local maps. An estimation of these relative locations is maintained with local map alignment algorithm, and more accurate estimation is calculated through a global minimization procedure using the loop closure constraint. The local map is built with Rao-Blackwellised particle filter (RBPF), where the particle filter is used to extending the path posterior by sampling new poses. The landmark position estimation and update is implemented through extended Kalman filter (EKF). Monocular vision mounted on the robot tracks the 3D natural point landmarks, which are structured with matching scale invariant feature transform (SIFT) feature pairs. The matching for multi-dimension SIFT features is implemented with a KD-tree in the time cost of O(lbN). Experiment results on Pioneer mobile robot in a real indoor environment show the superior performance of our proposed method. 展开更多
关键词 mobile robot HIERARCHICAL simultaneous localization and mapping (SLAM) Rao-Blackwellised particle filter (RBPF) MONOCULAR vision scale INVARIANT feature TRANSFORM
在线阅读 下载PDF
A Two-step Estimation Method of Troposphere Delay with Consideration of Mapping Function Errors 被引量:13
9
作者 Haopeng FAN Zhongmiao SUN +1 位作者 Liping ZHANG Xiaogang LIU 《Journal of Geodesy and Geoinformation Science》 2020年第1期76-84,共9页
Mapping function errors are usually not taken into consideration, when space geodetic data observed by VLBI, GNSS and some other techniques are utilized to estimate troposphere delay, which could, however, probably br... Mapping function errors are usually not taken into consideration, when space geodetic data observed by VLBI, GNSS and some other techniques are utilized to estimate troposphere delay, which could, however, probably bring non-ignorable errors to solutions. After analyzing the variation of mapping function errors with elevation angles based on several-year meteorological data, this paper constructed a model of this error and then proposed a two-step estimation method of troposphere delay with consideration of mapping function errors. The experimental results indicate that the method put forward by this paper could reduce the slant path delay residuals efficiently and improve the estimation accuracy of wet tropospheric delay to some extent. 展开更多
关键词 TROPOSPHERIC DELAY mapping function ERRORS Very Long BASELINE Interferometry parameter weighted adjustment European CENTRE for Medium-Range Weather Forecasts
在线阅读 下载PDF
Mapping editorial identity and thematic evolution in the Journal of Psychology in Africa(2008-2024):A meta-editorial framework analysis
10
作者 Joon-ho Kim 《Journal of Psychology in Africa》 2026年第1期117-130,共14页
This study presents a reflective bibliometric review of 1457 peer-reviewed articles published in the Journal of Psychology in Africa(2008-2024,17 years),using a Meta-Editorial Mapping Framework(MEMF)analysis.The MEMF ... This study presents a reflective bibliometric review of 1457 peer-reviewed articles published in the Journal of Psychology in Africa(2008-2024,17 years),using a Meta-Editorial Mapping Framework(MEMF)analysis.The MEMF integrates citation metrics,keyword novelty ratios,TF-IDF weighting,and cluster-based topic modeling to trace long-term thematic trends and editorial evolution.Findings reveal sustained attention to foundational domains such as mental health,education,and identity,alongside a gradual integration of emergent themes including digital well-being,organizational behavior,and post-pandemic adaptation.Articles with moderate topical novelty(40%-60% new keywords)achieved the highest citation and usage metrics,suggesting that integrative innovation enhances scholarly impact.Clustering analyses indicate that the journal’s content forms overlapping conceptual domains rather than isolated silos.These insights contribute to editorial strategy,authorial positioning,and the future design of regional academic platforms.Moreover,the findings provide evidence supporting the use of the MEMF as a replicable tool for meta-editorial analysis across disciplinary and geographic boundaries. 展开更多
关键词 meta-editorial mapping framework(MEMF) topic evolution keyword novelty bibliometric analysis editorial strategy scholarly engagement Journal of Psychology in Africa
在线阅读 下载PDF
Mapping epistasis and environment × QTX interaction based on four-omics genotypes for the detected QTX loci controlling complex traits in tobacco 被引量:4
11
作者 Liyuan Zhou Ruiyuan Li +6 位作者 Longjiang Fan Yuewei Shi Zhihong Wang Shengdong Xie Yijie Gui Xueliang Ren Jun Zhu 《The Crop Journal》 SCIE CAS 2013年第2期151-159,共9页
Using newly developed methods and software, association mapping was conducted for chromium content and total sugar in tobacco leaf, based on four-omics datasets. Our objective was to collect data on genotype and pheno... Using newly developed methods and software, association mapping was conducted for chromium content and total sugar in tobacco leaf, based on four-omics datasets. Our objective was to collect data on genotype and phenotype for 60 leaf samples at four developmental stages, from three plant architectural positions and for three cultivars that were grown in two locations. Association mapping was conducted to detect genetic variants at quantitative trait SNP(QTS) loci, quantitative trait transcript(QTT) differences,quantitative trait protein(QTP) variability, and quantitative trait metabolite(QTM) changes,which can be summarized as QTX locus variation. The total heritabilities of the four-omics loci for both traits tested were 23.60% for epistasis and 15.26% for treatment interaction.Epistasis and environment × treatment interaction had important impacts on complex traits at all-omics levels. For decreasing chromium content and increasing total sugar in tobacco leaf, six methylated loci can be directly used for marker-assisted selection, and expression of ten QTTs, seven QTPs and six QTMs can be modified by selection or cultivation. 展开更多
关键词 Association mapping study Complex trait analysis EPISTASIS effects ENVIRONMENT × treatment INTERACTION Plant architecture control QTX locus mapping
在线阅读 下载PDF
Utilization of Open Source Spatial Data for Landslide Susceptibility Mapping at Chittagong District of Bangladesh—An Appraisal for Disaster Risk Reduction and Mitigation Approach
12
作者 Md. Ashraful Islam Sanzida Murshed +4 位作者 S. M. Mainul Kabir Atikul Haque Farazi Md. Yousuf Gazi Israt Jahan Syed Humayun Akhter 《International Journal of Geosciences》 2017年第4期577-598,共22页
Since creation of spatial data is a costly and time consuming process, researchers, in this domain, in most of the cases rely on open source spatial attributes for their specific purpose. Likewise, the present researc... Since creation of spatial data is a costly and time consuming process, researchers, in this domain, in most of the cases rely on open source spatial attributes for their specific purpose. Likewise, the present research aims at mapping landslide susceptibility at the metropolitan area of Chittagong district of Bangladesh utilizing obtainable open source spatial data from various web portals. In this regard, we targeted a study region where rainfall induced landslides reportedly causes causalities as well as property damage each year. In this study, however, we employed multi-criteria evaluation (MCE) technique i.e., heuristic, a knowledge driven approach based on expert opinions from various discipline for landslide susceptibility mapping combining nine causative factors—geomorphology, geology, land use/land cover (LULC), slope, aspect, plan curvature, drainage distance, relative relief and vegetation in geographic information system (GIS) environment. The final susceptibility map was devised into five hazard classes viz., very low, low, moderate, high, and very high, representing 22 km2 (13%), 90 km2 (53%);24 km2 (15%);22 km2 (13%) and 10 km2 (6%) areas respectively. This particular study might be beneficial to the local authorities and other stake-holders, concerned in disaster risk reduction and mitigation activities. Moreover this study can also be advantageous for risk sensitive land use planning in the study area. 展开更多
关键词 Susceptibility mapping Open Source Spatial Data Heuristic Model Chittagong METROPOLITAN Area GEOGRAPHIC Information System (GIS) Disaster Risk Reduction
暂未订购
A Comprehensive Literature Review of AI-Driven Application Mapping and Scheduling Techniques for Network-on-Chip Systems
13
作者 Naveed Ahmad Muhammad Kaleem +5 位作者 Mourad Elloumi Muhammad Azhar Mushtaq Ahlem Fatnassi Mohd Fazil Anas Bilal Abdulbasit A.Darem 《Computer Modeling in Engineering & Sciences》 2026年第1期118-155,共38页
Network-on-Chip(NoC)systems are progressively deployed in connecting massively parallel megacore systems in the new computing architecture.As a result,application mapping has become an important aspect of performance ... Network-on-Chip(NoC)systems are progressively deployed in connecting massively parallel megacore systems in the new computing architecture.As a result,application mapping has become an important aspect of performance and scalability,as current trends require the distribution of computation across network nodes/points.In this paper,we survey a large number of mapping and scheduling techniques designed for NoC architectures.This time,we concentrated on 3D systems.We take a systematic literature review approach to analyze existing methods across static,dynamic,hybrid,and machine-learning-based approaches,alongside preliminary AI-based dynamic models in recent works.We classify them into several main aspects covering power-aware mapping,fault tolerance,load-balancing,and adaptive for dynamic workloads.Also,we assess the efficacy of each method against performance parameters,such as latency,throughput,response time,and error rate.Key challenges,including energy efficiency,real-time adaptability,and reinforcement learning integration,are highlighted as well.To the best of our knowledge,this is one of the recent reviews that identifies both traditional and AI-based algorithms for mapping over a modern NoC,and opens research challenges.Finally,we provide directions for future work toward improved adaptability and scalability via lightweight learned models and hierarchical mapping frameworks. 展开更多
关键词 Application mapping mapping techniques NETWORK-ON-CHIP system on chip optimisation
在线阅读 下载PDF
RNPC-net:Automatic recognition and mapping of weathering degree and groundwater condition of tunnel faces
14
作者 Xiang Wu Fengyan Wang +4 位作者 Jianping Chen Mingchang Wang Lina Cheng Chengyao Zhang Junke Xu 《Journal of Rock Mechanics and Geotechnical Engineering》 2026年第2期1138-1159,共22页
Accurate and rapid recognition of weathering degree(WD)and groundwater condition(GC)is essential for evaluating rock mass quality and conducting stability analyses in underground engineering.Conventional WD and GC rec... Accurate and rapid recognition of weathering degree(WD)and groundwater condition(GC)is essential for evaluating rock mass quality and conducting stability analyses in underground engineering.Conventional WD and GC recognition methods often rely on subjective evaluation by field experts,supplemented by field sampling and laboratory testing.These methods are frequently complex and timeconsuming,making it challenging to meet the rapidly evolving demands of underground engineering.Therefore,this study proposes a rock non-geometric parameter classification network(RNPC-net)to rapidly achieve the recognition and mapping ofWD and GC of tunnel faces.The hybrid feature extraction module(HFEM)in RNPC-net can fully extract,fuse,and utilize multi-scale features of images,enhancing the network's classification performance.Moreover,the designed adaptive weighting auxiliary classifier(AC)helps the network learn features more efficiently.Experimental results show that RNPC-net achieved classification accuracies of 0.8756 and 0.8710 for WD and GC,respectively,representing an improvement of approximately 2%e10%compared to other methods.Both quantitative and qualitative experiments confirm the effectiveness and superiority of RNPC-net.Furthermore,for WD and GC mapping,RNPC-net outperformed other methods by achieving the highest mean intersection over union(mIOU)across most tunnel faces.The mapping results closely align with measurements provided by field experts.The application of WD and GC mapping results to the rock mass rating(RMR)system achieved a transition from conventional qualitative to quantitative evaluation.This advancement enables more accurate and reliable rock mass quality evaluations,particularly under critical conditions of RMR. 展开更多
关键词 Tunnel face Weathering degree Groundwater condition RNPC-net Hybrid feature extraction module Recognition and mapping
在线阅读 下载PDF
5G Oriented Exponential Effective Signal to Interference plus Noise Ratio Mapping Algorithm Based on Channel Classification
15
作者 WU Haoran YE Jianfang 《Journal of Donghua University(English Edition)》 EI CAS 2018年第2期160-162,共3页
In the future the fifth generation( 5 G) communication systems,channel models may be very complicated and it is difficult to calculate equivalent signal to interference plus noise ratio( SINR)of a random fading channe... In the future the fifth generation( 5 G) communication systems,channel models may be very complicated and it is difficult to calculate equivalent signal to interference plus noise ratio( SINR)of a random fading channel. Therefore,methods for the calculation of equivalent SINR of a random fading channel are very necessary.In this paper,an enhanced algorithm on the exponential effective SINR mapping( EESM) model for random fading channels was proposed. First, the optimal adjustment parameters of typical channel fading models including extended pedestrian A( EPA)model,extended vehicular A( EVA) model and extended typical urban( ETU) model were obtained by simulation. Then the proposed solution was used to actualize channel classification according to the maximum multipath delay and the average power of the random channel. The solution can determine the typical channel closest to random channel for obtaining the optimal adjustment value of EESM. The evaluation results indicate that the proposed one can improve the whole system throughput significantly and meanwhile the accuracy of the link prediction algorithm is also guaranteed. 展开更多
关键词 the fifth generation (5G) SIGNAL to INTERFERENCE PLUS noiseratio (SINR) EXPONENTIAL EFFECTIVE SINR mapping (EESM) channel classification
在线阅读 下载PDF
Integration of Landsat and MODIS Imagery for Mapping 30-m Cotton Cultivation Areas in Xinjiang,China from 2000 to 2020
16
作者 TAN Zhuting TAN Zhenyu +1 位作者 DUAN Hongtao ZHANG Kaili 《Chinese Geographical Science》 2026年第1期97-108,I0001,共13页
Cotton is an important global cash crops that serve as the primary source of natural fiber for textiles.A thorough understand-ing of the long-term variations in cotton cultivation is vital for optimizing cotton cultiv... Cotton is an important global cash crops that serve as the primary source of natural fiber for textiles.A thorough understand-ing of the long-term variations in cotton cultivation is vital for optimizing cotton cultivation management and promoting the sustainable development of the cotton industry.Xinjiang is the primary cotton-producing region in China.However,long-term data of cotton cultiv-ation areas with high spatial resolution are unavailable for Xinjiang,China.Therefore,this study aimed to identify and map an accurate 30-m cotton cultivation area dataset in Xinjiang from 2000 to 2020 by applying a Random Forest(RF)-based method that integrates Landsat and Moderate Resolution Imaging Spectroradiometer(MODIS)images,and validated the applicability and accuracy of dataset at a large spatial scale.Then,this study analyzed the spatiotemporal variations and influencing factors of cotton cultivation in the study period.The results showed that a high classification accuracy was achieved(overall accuracy>85%,F1>0.80),strongly agreeing with county-level agricultural statistical yearbook data(R2>0.72).Significant spatiotemporal variation in the cotton cultivation areas was found in Xinjiang,with a total increase of 1131.26 kha from 2000 to 2020.Notably,cotton cultivation area in southern Xinjiang expan-ded substantially,with that in Aksu increasing from 20.10%in 2000 to 28.17%in 2020,representing an expansion of 374.29 kha.In northern Xinjiang,the cotton areas in the Tacheng region also exhibited significant increased by almost ten percentage points in the same period.In contrast,cotton cultivation in eastern Xinjiang declined,decreasing from 2.22%in 2000 to merely 0.24%in 2020.Standard deviation ellipse analysis revealed a‘northeast-southwest’spatial distribution,with the centroid consistently located in Aksu and shifting 102.96 km over the 20-yr period.Pearson correlation analysis indicated that socioeconomic factors had a stronger influence on cotton cultivation than climatic factors,with effective irrigation area(r=0.963,P<0.05)and total agricultural machinery power(r=0.823)showing significant positive correlations,whereas climatic variables exhibiting weak associations(r<0.200).These results provide valuable scientific data for informed agricultural management,sustainable development,and policymaking. 展开更多
关键词 cotton cultivation mapping long-term series LANDSAT Moderate Resolution Imaging Spectroradiometer(MODIS) remote sensing Xinjiang China
在线阅读 下载PDF
Native T1 mapping值显著延长心脏纤维瘤一例
17
作者 文涛 张辉 +3 位作者 甘铁军 胡万均 李世兰 张静 《磁共振成像》 北大核心 2026年第1期120-122,共3页
本研究为回顾性研究,遵守《赫尔辛基宣言》,并经兰州大学第二医院伦理委员会审核批准,免除受试者知情同意,批准文号:2025A-547。患儿,女,2月8天,因“发现心脏肿瘤2月”于2024年11月就诊于我院,患儿于2个月前出生后外院检查提示左心室肿... 本研究为回顾性研究,遵守《赫尔辛基宣言》,并经兰州大学第二医院伦理委员会审核批准,免除受试者知情同意,批准文号:2025A-547。患儿,女,2月8天,因“发现心脏肿瘤2月”于2024年11月就诊于我院,患儿于2个月前出生后外院检查提示左心室肿瘤,未予特殊诊治,现为进一步明确诊治收住我院心脏外科。患儿足月(38+6周)、顺产、无心脏肿瘤家族史。查体:心前区无隆起,心界不大,心音有力、律齐,胸骨左缘第2~3肋间可闻及3/6及吹风样杂音,静息血氧饱和度100%。 展开更多
关键词 Native T1 mapping
暂未订购
Rubber Tree Distribution Mapping in Northeast Thailand 被引量:2
18
作者 Zhe Li Jefferson M. Fox 《International Journal of Geosciences》 2011年第4期573-584,共12页
In many parts of mainland Southeast Asia rubber plantations are expanding rapidly in areas where the crop was not historically found. Monitoring and mapping the distribution of rubber trees in the region is necessary ... In many parts of mainland Southeast Asia rubber plantations are expanding rapidly in areas where the crop was not historically found. Monitoring and mapping the distribution of rubber trees in the region is necessary for developing a better understanding of the consequences of land-cover and land-use change on carbon and water cycles. In this study, we conducted rubber tree growth mapping in Northeast Thailand using Landsat 5 TM data. A Mahalanobis typicality method was used to identify different age rubber trees. Landsat 5 TM 30 m non-thermal reflective bands, NDVI and tasseled cap transformation components were selected as the model input metrics. The validation was carried out using provincial level agricultural statistical data on the rubber tree growth area. At regional (Northeast Thailand) and provincial scales, the estimates of mature and middle-age rubber stands produced from 30 m Landsat 5 TM data compared well (high statistical significance) with the provincial rubber tree growth statistical data. 展开更多
关键词 NORTHEAST Thailand Rubber Tree mapping Land-Use and LAND-COVER Change Mahalanobis TYPICALITY Kauth-Thomas Transformation LANDSAT 5 TM
暂未订购
T2 Mapping联合DWI序列评估直肠癌脉管侵犯价值研究
19
作者 李茜玮 陈安良 +2 位作者 王楠 林良杰 刘爱连 《中国CT和MRI杂志》 2026年第1期149-152,共4页
目的探讨T2 mapping与DWI序列预测直肠癌脉管侵犯的价值。方法回顾性分析经本院行3.0T MRI扫描且经术后病理证实的直肠癌脉管侵犯13例,脉管非侵犯20例,2名观察者分别于瘤体显示最大层面参考增强动脉期图像及DWI图像于T2 mapping及ADC图... 目的探讨T2 mapping与DWI序列预测直肠癌脉管侵犯的价值。方法回顾性分析经本院行3.0T MRI扫描且经术后病理证实的直肠癌脉管侵犯13例,脉管非侵犯20例,2名观察者分别于瘤体显示最大层面参考增强动脉期图像及DWI图像于T2 mapping及ADC图像上测量病灶T2值及ADC值。采用组内相关系数(intraclass correlation cofficient,ICC)评估两名观察者测量参数值的一致性。采用独立样本t检验或Mann-Whitney U检验分析两组病例各参数的差异。采用Logistic回归计算有统计学差异的参数联合评估直肠癌LVI的预测值。采用ROC曲线评估有差异参数单独或联合的诊断效能,并利用De-Long检验比较各ROC曲线间的差异。采用Pearson相关性检验分析两参数值的相关性。结果2名观察者测量T2值及ADC值一致性好(ICC>0.75)。脉管侵犯组的T2值及ADC值低于非脉管侵犯组(77.15±6.95ms、0.69±0.15mm^(2)/s vs 87.04±7.75ms、0.90±0.21 mm^(2)/s,P<0.05)。ADC值与ADC-T2联合鉴别两组疾病的AUC值比较差异具有统计学意义(P=0.036)。结论T2 mapping和DWI序列可预测直肠癌脉管侵犯,两序列联合效能提升,因此T2值与ADC值联合可为临床诊疗直肠癌脉管侵犯提供参考信息。 展开更多
关键词 T2 mapping成像
暂未订购
A Quantum Representation of the Homogeneous 5D Manifold and the Perelman Mappings of 5D onto Non-Homogeneous Lorentz 4D Manifolds 被引量:2
20
作者 Kai Wai Wong Peter Chin Wan Fung Wan Ki Chow 《Journal of Modern Physics》 2019年第5期557-575,共19页
The expression of the Maxwell magnetic monopole was employed to correlate the space to space projection that gives rise to the Gell-Mann standard model, and space to time projection which gives the leptons;and how doe... The expression of the Maxwell magnetic monopole was employed to correlate the space to space projection that gives rise to the Gell-Mann standard model, and space to time projection which gives the leptons;and how does it correlate to the Perelman mappings from the homogeneous 5D manifold to the Lorentz 4D manifold, together with correlating the physical consequences caused by the breaking of the Diagonal Long Range Order [DLRO] of the monopoles quantum states affected by the motion of massive particles in the Lorentz 4D boundary of the 5D manifold, which leads to gravitons and the gravity field via the General Relativity covariant Riemannian 4D curvatures metric equation. 展开更多
关键词 5D HOMOGENEOUS MANIFOLD Perelman mappingS Magnetic MONOPOLES Space Projections and Topological Symmetries COVARIANT RIEMANNIAN Curvature and Gravity
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部