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Improved spatio-temporal alignment measurement method for hull deformation
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作者 XU Dongsheng YU Yuanjin +1 位作者 ZHANG Xiaoli PENG Xiafu 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2024年第2期485-494,共10页
In this paper,an improved spatio-temporal alignment measurement method is presented to address the inertial matching measurement of hull deformation under the coexistence of time delay and large misalignment angle.Lar... In this paper,an improved spatio-temporal alignment measurement method is presented to address the inertial matching measurement of hull deformation under the coexistence of time delay and large misalignment angle.Large misalignment angle and time delay often occur simultaneously and bring great challenges to the accurate measurement of hull deformation in space and time.The proposed method utilizes coarse alignment with large misalignment angle and time delay estimation of inertial measurement unit modeling to establish a brand-new spatiotemporal aligned hull deformation measurement model.In addition,two-step loop control is designed to ensure the accurate description of dynamic deformation angle and static deformation angle by the time-space alignment method of hull deformation.The experiments illustrate that the proposed method can effectively measure the hull deformation angle when time delay and large misalignment angle coexist. 展开更多
关键词 inertial measurement spatio-temporal alignment hull deformation
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An Intelligent Framework for Resilience Recovery of FANETs with Spatio-Temporal Aggregation and Multi-Head Attention Mechanism
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作者 Zhijun Guo Yun Sun +2 位作者 YingWang Chaoqi Fu Jilong Zhong 《Computers, Materials & Continua》 SCIE EI 2024年第5期2375-2398,共24页
Due to the time-varying topology and possible disturbances in a conflict environment,it is still challenging to maintain the mission performance of flying Ad hoc networks(FANET),which limits the application of Unmanne... Due to the time-varying topology and possible disturbances in a conflict environment,it is still challenging to maintain the mission performance of flying Ad hoc networks(FANET),which limits the application of Unmanned Aerial Vehicle(UAV)swarms in harsh environments.This paper proposes an intelligent framework to quickly recover the cooperative coveragemission by aggregating the historical spatio-temporal network with the attention mechanism.The mission resilience metric is introduced in conjunction with connectivity and coverage status information to simplify the optimization model.A spatio-temporal node pooling method is proposed to ensure all node location features can be updated after destruction by capturing the temporal network structure.Combined with the corresponding Laplacian matrix as the hyperparameter,a recovery algorithm based on the multi-head attention graph network is designed to achieve rapid recovery.Simulation results showed that the proposed framework can facilitate rapid recovery of the connectivity and coverage more effectively compared to the existing studies.The results demonstrate that the average connectivity and coverage results is improved by 17.92%and 16.96%,respectively compared with the state-of-the-art model.Furthermore,by the ablation study,the contributions of each different improvement are compared.The proposed model can be used to support resilient network design for real-time mission execution. 展开更多
关键词 RESILIENCE cooperative mission FANET spatio-temporal node pooling multi-head attention graph network
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Spatio-Temporal Change of Dispersal Areas of Greater Kudu (Tragelaphus strepsiceros) in Lake Bogoria Landscape, Kenya
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作者 Beatrice Chepkoech Cheserek George Morara Ogendi Paul Mutua Makenzi 《Open Journal of Ecology》 2024年第3期183-198,共16页
Decline in wildlife populations is manifest globally, regionally and locally. A wildlife decline of 68% has been reported in Kenya’s rangelands with Baringo County experiencing more than 85% wildlife loss in the last... Decline in wildlife populations is manifest globally, regionally and locally. A wildlife decline of 68% has been reported in Kenya’s rangelands with Baringo County experiencing more than 85% wildlife loss in the last four decades. Greater Kudu (Tragelaphus strepsiceros) is endemic to Lake Bogoria landscape in Baringo County and constitutes a major tourist attraction for the region necessitating use of its photo on the County’s logo and thus a flagship species. Tourism plays a central role in Baringo County’s economy and is a major source of potential growth and employment creation. The study was carried out to assess spatio-temporal change of dispersal areas of Greater Kudu (GK) in Lake Bogoria landscape in the last four years for enhanced adaptive management and improved livelihoods. GK population distribution primary data collected in December 2022 and secondary data acquired from Lake Bogoria National Game Reserve (LBNGR) for 2019 and 2020 were digitized using in a Geographic Information System (GIS). Measures of dispersion and point pattern analysis (PPA) were used to analyze dispersal of GK population using GIS. Spatio-temporal change of GK dispersal in LBNR was evident thus the null hypothesis was rejected. It is recommended that anthropogenic activities contributing to GK’s habitat degradation be curbed by providing alternative livelihood sources and promoting community adoption of sustainable technologies for improved livelihoods. 展开更多
关键词 spatio-temporal Change Dispersal Greater Kudu (Tragelaphus Strepsiceros) Point Pattern Analysis (PPA) GIS
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Research on the Spatio-Temporal Evolution and Driving Forces of Green Spaces in the Central Urban Area of Zunyi City
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作者 Juan Du 《Journal of Architectural Research and Development》 2024年第4期8-16,共9页
Green space,as a medium for carrying out urban functions and guiding urban development,is becoming a scarce resource along with the urbanization process and the intensification of environmental problems.In the face of... Green space,as a medium for carrying out urban functions and guiding urban development,is becoming a scarce resource along with the urbanization process and the intensification of environmental problems.In the face of the spatial mismatch between high demand and low supply,it is of great significance to clarify the evolution mechanism of green space to undertake national spatial planning,protect the natural strategic resources in the urban fringe area,and promote the sustainable development of the“three living spaces.”The study focuses on the Zunyi City Center,selecting the 20 years of rapid development following its establishment as a city as the study period.It explores the dynamic evolution of green space and the main driving forces during different periods using remote-sensing image data.The study shows that from 2003 to 2023,the total scale of green space has an obvious decreasing trend along with the expansion of the urban built-up area.A large amount of arable land is being converted to construction land,resulting in a sudden decrease in arable land area.In the past 10 years,the comprehensive land use dynamics have accelerated.Still,the spatial difference has gradually narrowed,indicating that the overall development intensity of Zunyi City’s central urban area has increased.There is a gradual spread of the trend to the hilly areas.The limiting effect of the mountainous natural environment on the city’s development has gradually diminished under the superposition of external factors,such as economic development,industrial technological upgrading,and policy orientation so the importance of the effective protection and rational utilization of urban green space has become more prominent. 展开更多
关键词 Green space spatio-temporal evolution Driving force Zunyi city center
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Leveraging Transfer Learning for Spatio-Temporal Human Activity Recognition from Video Sequences 被引量:1
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作者 Umair Muneer Butt Hadiqa Aman Ullah +3 位作者 Sukumar Letchmunan Iqra Tariq Fadratul Hafinaz Hassan Tieng Wei Koh 《Computers, Materials & Continua》 SCIE EI 2023年第3期5017-5033,共17页
Human Activity Recognition(HAR)is an active research area due to its applications in pervasive computing,human-computer interaction,artificial intelligence,health care,and social sciences.Moreover,dynamic environments... Human Activity Recognition(HAR)is an active research area due to its applications in pervasive computing,human-computer interaction,artificial intelligence,health care,and social sciences.Moreover,dynamic environments and anthropometric differences between individuals make it harder to recognize actions.This study focused on human activity in video sequences acquired with an RGB camera because of its vast range of real-world applications.It uses two-stream ConvNet to extract spatial and temporal information and proposes a fine-tuned deep neural network.Moreover,the transfer learning paradigm is adopted to extract varied and fixed frames while reusing object identification information.Six state-of-the-art pre-trained models are exploited to find the best model for spatial feature extraction.For temporal sequence,this study uses dense optical flow following the two-stream ConvNet and Bidirectional Long Short TermMemory(BiLSTM)to capture longtermdependencies.Two state-of-the-art datasets,UCF101 and HMDB51,are used for evaluation purposes.In addition,seven state-of-the-art optimizers are used to fine-tune the proposed network parameters.Furthermore,this study utilizes an ensemble mechanism to aggregate spatial-temporal features using a four-stream Convolutional Neural Network(CNN),where two streams use RGB data.In contrast,the other uses optical flow images.Finally,the proposed ensemble approach using max hard voting outperforms state-ofthe-art methods with 96.30%and 90.07%accuracies on the UCF101 and HMDB51 datasets. 展开更多
关键词 Human activity recognition deep learning transfer learning neural network ensemble learning spatio-temporal
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Relationship between spatio-temporal evolution of soil pH and geological environment/surface cover in the eastern Nenjiang River Basin of Northeast China during the past 30 years 被引量:2
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作者 Guo-dong Liu Ming-hui Wei +3 位作者 Ze Yang Hong-ye Xiao Yi-he Zhang Na-na Fang 《China Geology》 CAS CSCD 2023年第3期369-382,共14页
To illuminate the spatio-temporal variation characteristics and geochemical driving mechanism of soil pH in the Nenjiang River Basin,the National Multi-objective Regional Geochemical Survey data of topsoil,the Second ... To illuminate the spatio-temporal variation characteristics and geochemical driving mechanism of soil pH in the Nenjiang River Basin,the National Multi-objective Regional Geochemical Survey data of topsoil,the Second National Soil Survey data and Normalized Difference Vegetation Index(NDVI)were analyzed.The areas of neutral and alkaline soil decreased by 21100 km^(2)and 30500 km^(2),respectively,while that of strongly alkaline,extremely alkaline,and strongly acidic soil increased by 19600 km^(2),18200 km^(2),and 15500 km^(2),respectively,during the past 30 years.NDVI decreased with the increase of soil pH when soil pH>8.0,and it was reversed when soil pH<5.0.There were significant differences in soil pH with various surface cover types,which showed an ascending order:Arbor<reed<maize<rice<high and medium-covered meadow<low-covered meadow<Puccinellia.The weathering products of minerals rich in K_(2)O,Na_(2)O,CaO,and MgO entered into the low plain and were enriched in different parts by water transportation and lake deposition,while Fe and Al remained in the low hilly areas,which was the geochemical driving mechanism.The results of this study will provide scientific basis for making scientific and rational decisions on soil acidification and salinization. 展开更多
关键词 Soil pH spatio-temporal variation Surface cover Soybean-maize-rice Woodland-grassland-wetland Saline-alkali land-sandy land Geological environment Land quality geochemical survey engineering Nenjiang River Basin
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LociScan,a tool for screening genetic marker combinations for plant variety discrimination
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作者 Yang Yang Hongli Tian +5 位作者 Hongmei Yi Zi Shi Lu Wang Yaming Fan Fengge Wang Jiuran Zhao 《The Crop Journal》 SCIE CSCD 2024年第2期583-593,共11页
To reduce the cost and increase the efficiency of plant genetic marker fingerprinting for variety discrimination,it is desirable to identify the optimal marker combinations.We describe a marker combination screening m... To reduce the cost and increase the efficiency of plant genetic marker fingerprinting for variety discrimination,it is desirable to identify the optimal marker combinations.We describe a marker combination screening model based on the genetic algorithm(GA)and implemented in a software tool,Loci Scan.Ratio-based variety discrimination power provided the largest optimization space among multiple fitness functions.Among GA parameters,an increase in population size and generation number enlarged optimization depth but also calculation workload.Exhaustive algorithm afforded the same optimization depth as GA but vastly increased calculation time.In comparison with two other software tools,Loci Scan accommodated missing data,reduced calculation time,and offered more fitness functions.In large datasets,the sample size of training data exerted the strongest influence on calculation time,whereas the marker size of training data showed no effect,and target marker number had limited effect on analysis speed. 展开更多
关键词 Plant variety discrimination Genetic marker combination variety discrimination power Genetic algorithm
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Spatio-Temporal Analysis of Drought in the North-Eastern Coastal Region of Vietnam Using the Standardized Precipitation Index (SPI)
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作者 Nguyen Van Tuan Nguyen Van Hieu +5 位作者 Nguyen Khac Bang Pham Hoang Hai Nguyen Khanh Van Le Vinh Ha Tran Thi Hoa Lê Trọng Hiếu 《Atmospheric and Climate Sciences》 CAS 2023年第2期175-200,共26页
Spatio-temporal analysis of drought provides valuable information for drought management and damage mitigation. In this study, the Standardized Precipitation Index at the time scale of 6 months (SPI-6) is selected to ... Spatio-temporal analysis of drought provides valuable information for drought management and damage mitigation. In this study, the Standardized Precipitation Index at the time scale of 6 months (SPI-6) is selected to reflect drought conditions in the North-Eastern coastal region of Vietnam. The drought events and their characteristics from 1981 to 2019 are detected at 9 meteorological stations and 10 Chirps rainfall stations. The spatio-temporal variation of drought in the study region is analyzed on the basis of the number, duration, severity, intensity, and peak of the detected drought events at the 19 stations. The results show that from 1981 to 2019 the drought events mainly occurred with 1-season duration and moderate intensity and peak. The number, duration, severity, and peak of the drought events were the greatest in the period 2001-2010 and were the smallest in the period 2011-2019. Among the 19 stations, the drought duration tends to decrease at 11 stations, increase at 7 stations, and has a slight variant at 1 station;the drought severity tends to decrease at 14 stations, increase at 4 stations, and has not a significant trend at 1 station;the drought intensity tends to decrease at 17 stations, increase at 1 station, and has a slight variant at 1 station;and the drought peak tends to decrease at 18 stations and increase at 1 station. 展开更多
关键词 spatio-temporal Analysis of Drought Standardized Precipitation Index (SPI) Drought Characteristics
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Dynamic Spatio-Temporal Modeling in Disease Mapping
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作者 Flavian Awere Otieno Cox Lwaka Tamba +1 位作者 Justin Obwoge Okenye Luke Akong’o Orawo 《Open Journal of Statistics》 2023年第6期893-916,共24页
Spatio-temporal models are valuable tools for disease mapping and understanding the geographical distribution of diseases and temporal dynamics. Spatio-temporal models have been proven empirically to be very complex a... Spatio-temporal models are valuable tools for disease mapping and understanding the geographical distribution of diseases and temporal dynamics. Spatio-temporal models have been proven empirically to be very complex and this complexity has led many to oversimply and model the spatial and temporal dependencies independently. Unlike common practice, this study formulated a new spatio-temporal model in a Bayesian hierarchical framework that accounts for spatial and temporal dependencies jointly. The spatial and temporal dependencies were dynamically modelled via the matern exponential covariance function. The temporal aspect was captured by the parameters of the exponential with a first-order autoregressive structure. Inferences about the parameters were obtained via Markov Chain Monte Carlo (MCMC) techniques and the spatio-temporal maps were obtained by mapping stable posterior means from the specific location and time from the best model that includes the significant risk factors. The model formulated was fitted to both simulation data and Kenya meningitis incidence data from 2013 to 2019 along with two covariates;Gross County Product (GCP) and average rainfall. The study found that both average rainfall and GCP had a significant positive association with meningitis occurrence. Also, regarding geographical distribution, the spatio-temporal maps showed that meningitis is not evenly distributed across the country as some counties reported a high number of cases compared with other counties. 展开更多
关键词 spatio-temporal Model Matern Exponential Covariance Function Spatial and Temporal Dependencies Markov Chain Monte Carlo (MCMC)
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“stppSim”: A Novel Analytical Tool for Creating Synthetic Spatio-Temporal Point Data
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作者 Monsuru Adepeju 《Open Journal of Modelling and Simulation》 2023年第4期99-116,共18页
In crime science, understanding the dynamics and interactions between crime events is crucial for comprehending the underlying factors that drive their occurrences. Nonetheless, gaining access to detailed spatiotempor... In crime science, understanding the dynamics and interactions between crime events is crucial for comprehending the underlying factors that drive their occurrences. Nonetheless, gaining access to detailed spatiotemporal crime records from law enforcement faces significant challenges due to confidentiality concerns. In response to these challenges, this paper introduces an innovative analytical tool named “stppSim,” designed to synthesize fine-grained spatiotemporal point records while safeguarding the privacy of individual locations. By utilizing the open-source R platform, this tool ensures easy accessibility for researchers, facilitating download, re-use, and potential advancements in various research domains beyond crime science. 展开更多
关键词 OPEN-SOURCE Synthetic Data CRIME spatio-temporal Patterns Data Privacy
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Effect of Variety and Plant Spacing on Growth and Yield of Groundnuts (Arachis hypogaea L.)
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作者 Abukari Iddrisu Eric Adjei +3 位作者 Samuel Kwesi Asomaning Kwadwo Gyasi Santo Adu Poku Isaac Alexander Danson-Anokye 《Agricultural Sciences》 2024年第1期54-70,共17页
A field experiment was carried out to determine the effect of variety and plant spacing on yield and growth of groundnuts. The field experiment was laid in a 3 × 3 factorial experiment in a Randomized Complete Bl... A field experiment was carried out to determine the effect of variety and plant spacing on yield and growth of groundnuts. The field experiment was laid in a 3 × 3 factorial experiment in a Randomized Complete Block Design (RCBD) with three (3) replications. The factor A included three (3) groundnut varieties (Nkatie Sari, Sum Nutt 22 and Yenyawoso) and Factor B was the three (3) spacing of 30 cm × 15 cm, 30 cm × 30 cm and 30 cm × 40 cm. All recommended agronomic practices were followed. Data was collected from eight (8) tagged plants. Growth data were recorded on plant height, number of branches, number of leaves, and the number of flowers while yield data were collected on the number of flowers, number of pods per plant, 100 seeds weight and the pod yield (kg/ha). The plant spacing significantly influenced (P < 0.05) the growth and yield parameters. Groundnut grown at a spacing of 30 cm × 15 cm produced the maximum plant height, whereas the maximum number of leaves, number of branches and number of flowers were produced from 30 cm × 40 cm. Yenyawoso variety with a wider plant spacing performed better vegetatively among all the varieties. The Yenyawoso variety produced the highest number of pods, 100 seeds weight and pod yield as compared to the other varieties. Also, Yenyawoso at 30 cm × 40 cm spacing and Nkatie Sari at 30 cm × 15 cm spacing produced the maximum pod yield. 展开更多
关键词 GROUNDNUT variety YIELD SPACING Plant Height
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Subplanes of PG( 2, q 3 ) and the Ruled Varieties V 2 5 of PG( 6,q )
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作者 Rita Vincenti 《Open Journal of Discrete Mathematics》 2024年第2期16-27,共12页
In this note we study subplanes of order q of the projective plane Π=PG( 2, q 3 ) and the ruled varieties V 2 5 of Σ=PG( 6,q ) using the spatial representation of Π in Σ, by fixing a hyperplane Σ ′ with a regula... In this note we study subplanes of order q of the projective plane Π=PG( 2, q 3 ) and the ruled varieties V 2 5 of Σ=PG( 6,q ) using the spatial representation of Π in Σ, by fixing a hyperplane Σ ′ with a regular spread of planes. First are shown some configurations of the affine q-subplanes. Then to prove that a variety V 2 5 of Σ represents a non-affine subplane of order q of Π, after having shown basic incidence properties of it, such a variety V 2 5 is constructed by choosing appropriately the two directrix curves in two complementary subspaces of Σ. The result can be translated into further incidence properties of the affine points of V 2 5 . Then a maximal bundle of varieties V 2 5 having in common one directrix cubic curve is constructed. 展开更多
关键词 Finite Geometry Translation Planes SPREADS VARIETIES
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Construction of apricot variety search engine based on deep learning
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作者 Chen Chen Lin Wang +8 位作者 Huimin Liu Jing Liu Wanyu Xu Mengzhen Huang Ningning Gou Chu Wang Haikun Bai Gengjie Jia Tana Wuyun 《Horticultural Plant Journal》 SCIE CAS CSCD 2024年第2期387-397,共11页
Apricot has a long history of cultivation and has many varieties and types. The traditional variety identification methods are timeconsuming and labor-consuming, posing grand challenges to apricot resource management.... Apricot has a long history of cultivation and has many varieties and types. The traditional variety identification methods are timeconsuming and labor-consuming, posing grand challenges to apricot resource management. Tool development in this regard will help researchers quickly identify variety information. This study photographed apricot fruits outdoors and indoors and constructed a dataset that can precisely classify the fruits using a U-net model (F-score:99%), which helps to obtain the fruit's size, shape, and color features. Meanwhile, a variety search engine was constructed, which can search and identify variety from the database according to the above features. Besides, a mobile and web application (ApricotView) was developed, and the construction mode can be also applied to other varieties of fruit trees.Additionally, we have collected four difficult-to-identify seed datasets and used the VGG16 model for training, with an accuracy of 97%, which provided an important basis for ApricotView. To address the difficulties in data collection bottlenecking apricot phenomics research, we developed the first apricot database platform of its kind (ApricotDIAP, http://apricotdiap.com/) to accumulate, manage, and publicize scientific data of apricot. 展开更多
关键词 APRICOT variety Convolutional neural network Deep learning Database platform Mobile application Image retrieval
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Variety Selection and Green Cultivation Technology of Courtyard Ornamental and Edible Peppers
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作者 Xilu ZHANG Shengying JI +2 位作者 Yinglin YE Xingzhi DING Juan CHEN 《Plant Diseases and Pests》 2024年第3期26-30,共5页
In order to comply with the development trend of the multifunctional use of peppers,we conducted an investigation into the characteristics and features of varieties,potting management techniques,and the methods of ext... In order to comply with the development trend of the multifunctional use of peppers,we conducted an investigation into the characteristics and features of varieties,potting management techniques,and the methods of extending the fruit ornamental period and other aspects of courtyard ornamental and edible peppers.A set of cultivation techniques suitable for courtyard ornamental and edible peppers has been developed,including timely sowing and seedling,nutrient soil preparation,water and fertilizer management,trimming and pruning,preservation of flowers and fruits,green prevention and control of diseases and pests,harvesting,and so on. 展开更多
关键词 Ornamental and edible pepper Courtyard gardening variety characteristics Cultivation technique
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An Application of Machine Learning Methods to Detect Mango Varieties
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作者 Abou Bakary Ballo Moustapha Diaby Adama Coulibaly 《Open Journal of Applied Sciences》 2024年第7期1666-1690,共25页
The mango, a fruit of immense economic and dietary significance in numerous tropical and subtropical regions, plays a pivotal role in our agricultural landscape. Accurate identification is not just a necessity, but a ... The mango, a fruit of immense economic and dietary significance in numerous tropical and subtropical regions, plays a pivotal role in our agricultural landscape. Accurate identification is not just a necessity, but a crucial step for effective classification, sorting, and marketing. This study delves into the potential of machine learning for this task, comparing the performance of four models: MobileNetV2, Xception, VGG16, and ResNet50V2. These models were trained on a dataset of annotated mango images, and their performance was evaluated using precision, accuracy, F1 score, and recall, which are standard metrics for image classification. The Xception model, with its exceptional performance, outshone the other models on all performance indicators. It achieved a staggering accuracy of 99.47%, an F1 score of 99.43%, and a recall of 99.43%, showcasing its remarkable ability to accurately identify mango varieties. MobileNetV2 followed closely with performances of 98.95% accuracy, 98.85% F1 score, and 98.86% recall. ResNet50V2 also delivered satisfactory results with 97.39% accuracy, 97.08% F1 score, and 97.17% recall. VGG16, however, was the least effective, with a precision rate of 83.25%, an F1 score of 83.25%, and a recall of 85.47%. These results confirm the superiority of the Xception model in detecting mango varieties. Its advanced architecture allows it to capture more distinguishing features of mango images, leading to greater precision and reliability. Xception’s robustness in identifying true positives is another advantage, minimizing false positives and contributing to more accurate classification. This study highlights the promising potential of machine learning, particularly the Xception model, for accurately identifying mango varieties. 展开更多
关键词 Machine Learning Recognition Mango Varieties ALGORITHMS Feature Extraction CONVOLUTION TRAINING Classification
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Spatio-temporal GIS和GPS优化集成在城市交通管制中的应用研究 被引量:1
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作者 朱洪军 郑方艳 《国土资源信息化》 2007年第4期33-37,共5页
本文基于城市交通日益恶化现状和3S集成的迅速发展,表述了Spatio-temporal GIS的定义、时空路径、人类活动的四种时空关系及其坐标系统模型的建立;并根据GPS空间定位、空间导航的原理和模型,将Spatio-temporal GIS和GPS的功能优化集成,... 本文基于城市交通日益恶化现状和3S集成的迅速发展,表述了Spatio-temporal GIS的定义、时空路径、人类活动的四种时空关系及其坐标系统模型的建立;并根据GPS空间定位、空间导航的原理和模型,将Spatio-temporal GIS和GPS的功能优化集成,阐述了其对城市交通信息的收集、分析、显示等功能;最后论述了Spatio-temporal GIS和GPS的集成对城市交通预警、报警、协调等管制作用。 展开更多
关键词 spatio-temporal GIS GPS 城市交通
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Characteristics,Processes,and Causes of the Spatio-temporal Variabilities of the East Asian Monsoon System 被引量:69
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作者 黄荣辉 陈际龙 +1 位作者 王林 林中达 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2012年第5期910-942,共33页
Recent advances in the study of the characteristics, processes, and causes of spatio-temporal variabilities of the East Asian monsoon (EAM) system are reviewed in this paper. The understanding of the EAM system has ... Recent advances in the study of the characteristics, processes, and causes of spatio-temporal variabilities of the East Asian monsoon (EAM) system are reviewed in this paper. The understanding of the EAM system has improved in many aspects: the basic characteristics of horizontal and vertical structures, the annual cycle of the East Asian summer monsoon (EASM) system and the East Asian winter monsoon (EAWM) system, the characteristics of the spatio-temporal variabilities of the EASM system and the EAWM system, and especially the multiple modes of the EAM system and their spatio-temporal variabilities. Some new results have also been achieved in understanding the atmosphere-ocean interaction and atmosphere-land interaction processes that affect the variability of the EAM system. Based on recent studies, the EAM system can be seen as more than a circulation system, it can be viewed as an atmosphere-ocean-land coupled system, namely, the EAM climate system. In addition, further progress has been made in diagnosing the internal physical mechanisms of EAM climate system variability, especially regarding the characteristics and properties of the East Asia-Pacific (EAP) teleconnection over East Asia and the North Pacific, the "Silk Road" teleconnection along the westerly jet stream in the upper troposphere over the Asian continent, and the dynamical effects of quasi-stationary planetary wave activity on EAM system variability. At the end of the paper, some scientific problems regarding understanding the EAM system variability are proposed for further study. 展开更多
关键词 East Asian monsoon system spatio-temporal variations climate system EAP teleconnection
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Spatio-temporal Variability of Northern Hemipheric Sea Level Pressure(SLP)and Precipitation over the Mid-to-Low Reaches of the Yangtze River 被引量:13
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作者 韩雪 魏凤英 +1 位作者 Yves M.TOURRE 董文杰 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2008年第3期458-466,共9页
The spatio-temporal variability of Northern Hemisphere Sea Level Pressure (SLP) and precipitation over the mid-to-low reaches of the Yangtze River (PMLY) is analyzed jointly using the multi-taper/singular value de... The spatio-temporal variability of Northern Hemisphere Sea Level Pressure (SLP) and precipitation over the mid-to-low reaches of the Yangtze River (PMLY) is analyzed jointly using the multi-taper/singular value decomposition method (MTM-SVD). Statistically significant narrow frequency bands are obtained from the local fractional variance (LFV) spectrum. Significant interdecadal (i.e., 16-to-18-year periods) and interannual (i.e., 3-to-6-year periods) signals are identified. Moreover, a significant quasi-biennial signal is identified but only for PMLY data. The spatial joint evolution of patterns obtained for peaks in the LFV spectrum sheds light on relationships between SLP and PMLY: the Arctic Oscillation (AO) modulates the variability of the PMLY while the interannual variability of PMLY is in phase with the Northern Atlantic Oscillation (NAO) and the Northern Pacific Oscillation (NPO). 展开更多
关键词 MTM-SVD coupled spatio-temporal characteristics
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Spatio-Temporal Changes in the Rice Planting Area and Their Relationship to Climate Change in Northeast China: A Model-Based Analysis 被引量:14
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作者 XIA Tian WU Wen-bin +5 位作者 ZHOU Qing-bo YU Qiang-yi Peter H Verburg YANG Peng LU Zhong-jun TANG Hua-jun 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2014年第7期1575-1585,共11页
Rice is one of the most important grain crops in Northeast China (NEC) and its cultivation is sensitive to climate change. This study aimed to explore the spatio-temporal changes in the NEC rice planting area over t... Rice is one of the most important grain crops in Northeast China (NEC) and its cultivation is sensitive to climate change. This study aimed to explore the spatio-temporal changes in the NEC rice planting area over the period of 1980-2010 and to analyze their relationship to climate change. To do so, the CLUE-S (conversion of land use and its effects at small region extent) model was ifrst updated and used to simulate dynamic changes in the rice planting area in NEC to understand spatio-temporal change trends during three periods: 1980-1990, 1990-2000 and 2000-2010. The changing results in individual periods were then linked to climatic variables to investigate the climatic drivers of these changes. Results showed that the NEC rice planting area expanded quickly and increased by nearly 4.5 times during 1980-2010. The concentration of newly planted rice areas in NEC constantly moved northward and the changes were strongly dependent on latitude. This conifrmed that climate change, increases in temperature in particular, greatly inlfuenced the shift in the rice planting area. The shift in the north limit of the NEC rice planting area generally followed a 1&#176;C isoline migration pattern, but with an obvious time-lag effect. These ifndings can help policy makers and crop producers take proper adaptation measures even when exposed to the global warming situation in NEC. 展开更多
关键词 spatio-temporal change rice planting area climate change Northeast China
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Spatio-temporal patterns of drought in North Xinjiang, China, 1961–2012 based on meteorological drought index 被引量:8
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作者 WU Yanfeng Batur BAKE +1 位作者 ZHANG Jusong Hamid RASULOV 《Journal of Arid Land》 SCIE CSCD 2015年第4期527-543,共17页
Drought, which is one of the most frequently occurring severe hazards with long time scales and cov- ering wide geographical areas, is a natural phenomenon resulting in significant economic losses in agriculture and i... Drought, which is one of the most frequently occurring severe hazards with long time scales and cov- ering wide geographical areas, is a natural phenomenon resulting in significant economic losses in agriculture and industry. Drought is caused by an imbalance between the inputs of and the demand for water which is insufficient to meet the demands of human activities and the eco-environment. As a major arid and semi-arid area and an important agricultural region in Northwest China, North Xinjiang (NX) shows great vulnerability to drought. In this paper, the characteristics of inter-annual and seasonal drought were analyzed in terms of drought occurrence and drought coverage, by using the composite index of meteorological drought and the data of daily precipitation, air temperature, wind speed, relative humidity and sunshine duration from 38 meteorological stations during the period 1961-2012. Trend analysis, wavelet analysis and empirical orthogonal function were also applied to investigate change trend, period and regional characteristics, respectively. In NX, annual and seasonal drought occurrence and drought coverage all showed a decreasing trend that was most significant in winter (with rates of-0.26 month/10a and -15.46%, respectively), and drought occurrence in spring and summer were more frequent than that in autumn and winter. Spatially, drought was severe in eastern regions but mild in western regions of NX. Annual and seasonal drought occurrence at 38 meteorological stations displayed decreasing trends and were most significant in "Shi- hezi-Urumqi-Changji", which can help to alleviate severe drought hazards for local agricultural production and improve human livelihood. NX can be approximately classified into three sub-regions (severe drought region, moder- ate drought region and mild drought region), which were calculated from annual drought frequencies. The cross wavelet transform suggested that SOl (Southern Oscillation Index), AOI (Arctic Oscillation Index), AAOI (Antarctic Oscillation Index), PAOI (Pacific/North American Oscillation Index) and NAOI (North Atlantic Oscillation Index) have significant correlation with the variation of drought occurrence in NX. To prevent and mitigate the occurrence of drought disasters in NX, agricultural and government managers should pay more attention to those drought events that occur in spring and summer. 展开更多
关键词 DROUGHT spatio-temporal pattern drought indices North Xinjiang
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