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Discrete Choice Analysis of Temporal Factors on Social Network Growth
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作者 Kwok-Wai Cheung Yuk Tai Siu 《Intelligent Information Management》 2024年第1期21-34,共14页
Social networks like Facebook, X (Twitter), and LinkedIn provide an interaction and communication environment for users to generate and share content, allowing for the observation of social behaviours in the digital w... Social networks like Facebook, X (Twitter), and LinkedIn provide an interaction and communication environment for users to generate and share content, allowing for the observation of social behaviours in the digital world. These networks can be viewed as a collection of nodes and edges, where users and their interactions are represented as nodes and the connections between them as edges. Understanding the factors that contribute to the formation of these edges is important for studying network structure and processes. This knowledge can be applied to various areas such as identifying communities, recommending friends, and targeting online advertisements. Several factors, including node popularity and friends-of-friends relationships, influence edge formation and network growth. This research focuses on the temporal activity of nodes and its impact on edge formation. Specifically, the study examines how the minimum age of friends-of-friends edges and the average age of all edges connected to potential target nodes influence the formation of network edges. Discrete choice analysis is used to analyse the combined effect of these temporal factors and other well-known attributes like node degree (i.e., the number of connections a node has) and network distance between nodes. The findings reveal that temporal properties have a similar impact as network proximity in predicting the creation of links. By incorporating temporal features into the models, the accuracy of link prediction can be further improved. 展开更多
关键词 Discrete Choice models temporal Factors Social Network Link Prediction Network Growth
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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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Spatio-temporal Heterogeneity in the Performance of Rural Revitalization in Chifeng City of China:Based on a Range-wide EBM-GML Model
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作者 Jiajing Li Jianing Li Pei Zhang 《Journal of Geographical Research》 2023年第2期15-33,共19页
To solve the problems of rural revitalization performance research,a quantitative model of non-oriented range-wide EBM(Epsilon-Based Measure)-GML(Global-Malmquist)based on VRS(Variable Returns to Scale)conditions incl... To solve the problems of rural revitalization performance research,a quantitative model of non-oriented range-wide EBM(Epsilon-Based Measure)-GML(Global-Malmquist)based on VRS(Variable Returns to Scale)conditions including non-desired outputs is constructed.A comprehensive spatio-temporal heterogeneity research index system of rural revitalization performance is also constructed.Taking the typical rural in Chifeng City as an example,the panel data from 2016-2020 are selected for empirical analysis,the conclusions and countermeasures are suggested as follows:1)In general,the rural revitalization performance of Chifeng City increases significantly during the five-year period,with significant spatio-temporal heterogeneity.The overall analysis shows that the overall performance value of rural revitalization in Chifeng City is 0.683 from 2016 to 2020.The highest performance value is 1 and the lowest performance value is 0.389.The performance growth rate increases year by year,with an average annual growth rate of 4.46%.2)From 2016 to 2020,the GML index of rural revitalization performance in Chifeng City is 1.174,showing an increasing trend.Based on the range of change of GML index,Chifeng City can be classified into three types:Continuous improvement,fluctuating improvement and fluctuating decline.3)Niujiayingzi,Guandongche,Zhaidamu,and Qiangangtai rural have the highest degree of technological progress. 展开更多
关键词 Rural revitalization Performance EBM model GML index Spatio and temporal heterogeneity Chifeng City
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Temporal and spatial distribution characteristics of water resources in Guangdong Province based on a cloud model 被引量:9
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作者 Qi Zhou Wei Wang +2 位作者 Yong Pang Zhi-yong Zhou Hui-ping Luo 《Water Science and Engineering》 EI CAS CSCD 2015年第4期263-272,共10页
With a focus on the difficulty of quantitatively describing the degree of nonuniformity of temporal and spatial distributions of water resources, quantitative research was carried out on the temporal and spatial distr... With a focus on the difficulty of quantitatively describing the degree of nonuniformity of temporal and spatial distributions of water resources, quantitative research was carried out on the temporal and spatial distribution characteristics of water resources in Guangdong Province from 1956 to 2000 based on a cloud model. The spatial variation of the temporal distribution characteristics and the temporal variation of the spatial distribution characteristics were both analyzed. In addition, the relationships between the numerical characteristics of the cloud model of temporal and spatial distributions of water resources and precipitation were also studied. The results show that, using a cloud model, it is possible to intuitively describe the temporal and spatial distribution characteristics of water resources in cloud images. Water resources in Guangdong Province and their temporal and spatial distribution characteristics are differentiated by their geographic locations. Downstream and coastal areas have a larger amount of water resources with greater uniformity and stronger stability in terms of temporal distribution. Regions with more precipitation possess larger amounts of water resources, and years with more precipitation show greater nonuniformity in the spatial distribution of water resources. The correlation between the nonuniformity of the temporal distribution and local precipitation is small, and no correlation is found between the stability of the nonuniformity of the temporal and spatial distributions of water resources and precipitation. The amount of water resources in Guangdong Province shows an increasing trend from 1956 to 2000, the nonuniformity of the spatial distribution of water resources declines, and the stability of the nonuniformity of the spatial distribution of water resources is enhanced. 展开更多
关键词 Water resources temporal and spatial distribution characteristics Cloud model Guangdong Province
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ISDTM:An Intrusion Signatures Description Temporal Model 被引量:1
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作者 OuYangMing-guang ZhouYang-bo 《Wuhan University Journal of Natural Sciences》 CAS 2003年第02A期373-378,共6页
ISDTM, based on an augmented Allen's interval temporal logic (ITL) and first-order predicate calculus, is a formal temporal model for representing intrusion signatures. It is augmented with some real time extensio... ISDTM, based on an augmented Allen's interval temporal logic (ITL) and first-order predicate calculus, is a formal temporal model for representing intrusion signatures. It is augmented with some real time extensions which enhance the expressivity. Intrusion scenarios usually are the set of events and system states, where- the temporal sequence is their basic relation. Intrusion signatures description, therefore , is to represent such temporal relations in a sense. While representing these signatures, ISDTM decomposes the intrusion process into the sequence of events according to their relevant intervals, and then specifies network states in these Intervals. The uncertain intrusion signatures as well as basic temporal modes of events, which consist of the parallel mode, the sequential mode and the hybrid mode, can be succinctly and naturally represented in ISDTM. Mode chart is the visualization of intrusion signatures in ISDTM, which makes the formulas more readable. The intrusion signatures descriptions in ISDTM have advantages of compact construct, concise syntax, scalability and easy implementation. 展开更多
关键词 ISDTM uncertain intrusion signatures intru-sion detection temporal model
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Spatio-temporal GIS Data Model Based on Event Semantics 被引量:5
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作者 XUZhihong BIANFuling 《Geo-Spatial Information Science》 2003年第3期43-47,共5页
There are mainly four kinds of models to record and deal with historical information. By taking them as reference, the spatio-temporal model based on event semantics is proposed. In this model, according to the way fo... There are mainly four kinds of models to record and deal with historical information. By taking them as reference, the spatio-temporal model based on event semantics is proposed. In this model, according to the way for describing an event, all the information are divided into five domains. This paper describes the model by using the land parcel change in the cadastral information system, and expounds the model by using five tables corresponding to the five domains. With the aid of this model, seven examples are given on historical query, trace back and recurrence. This model can be implemented either in the extended relational database or in the object-oriented database. 展开更多
关键词 GIS 地理信息系统 数字模型 时空模型 遥感技术 RS
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Ensemble Based Temporal Weighting and Pareto Ranking (ETP) Model for Effective Root Cause Analysis 被引量:1
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作者 Naveen Kumar Seerangan S.Vijayaragavan Shanmugam 《Computers, Materials & Continua》 SCIE EI 2021年第10期819-830,共12页
Root-cause identification plays a vital role in business decision making by providing effective future directions for the organizations.Aspect extraction and sentiment extraction plays a vital role in identifying the ... Root-cause identification plays a vital role in business decision making by providing effective future directions for the organizations.Aspect extraction and sentiment extraction plays a vital role in identifying the rootcauses.This paper proposes the Ensemble based temporal weighting and pareto ranking(ETP)model for Root-cause identification.Aspect extraction is performed based on rules and is followed by opinion identification using the proposed boosted ensemble model.The obtained aspects are validated and ranked using the proposed aspect weighing scheme.Pareto-rule based aspect selection is performed as the final selection mechanism and the results are presented for business decision making.Experiments were performed with the standard five product benchmark dataset.Performances on all five product reviews indicate the effective performance of the proposed model.Comparisons are performed using three standard state-of-the-art models and effectiveness is measured in terms of F-Measure and Detection rates.The results indicate improved performances exhibited by the proposed model with an increase in F-Measure levels at 1%–15%and detection rates at 4%–24%compared to the state-of-the-art models. 展开更多
关键词 Root cause analysis sentiment analysis aspect extraction ensemble modelling temporal weighting pareto ranking
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WHU-Grace01s:A new temporal gravity field model recovered from GRACE KBRR data alone 被引量:2
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作者 Zhou Hao Luo Zhicai Zhong Bo 《Geodesy and Geodynamics》 2015年第5期316-323,共8页
A new temporal gravity field model called WHU-Grace01s solely recovered from Gravity Recovery and Climate Experiment (GRACE) K-Band Range Rate (KBRR) data based on dynamic integral approach is presented in this pa... A new temporal gravity field model called WHU-Grace01s solely recovered from Gravity Recovery and Climate Experiment (GRACE) K-Band Range Rate (KBRR) data based on dynamic integral approach is presented in this paper. After meticulously preprocessing of the GRACE KBRR data, the root mean square of its post residuals is about 0.2 micrometers per second, and seventy-two monthly temporal solutions truncated to degree and order 60 are computed for the period from January 2003 to December 2008. After applying the combi- nation filter in WHU-Grace01s, the global temporal signals show obvious periodical change rules in the large-scale fiver basins. In terms of the degree variance, our solution is smaller at high degrees, and shows a good consistency at the rest of degrees with the Release 05 models from Center for Space Research (CSR), GeoForschungsZentrum Potsdam (GFZ) and Jet Pro- pulsion Laboratory 0PL). Compared with other published models in terms of equivalent water height distribution, our solution is consistent with those published by CSR, GFZ, JPL, Delft institute of Earth Observation and Space system (DEOS), Tongji University (Tongji), Institute of Theoretical Geodesy (ITG), Astronomical Institute in University of Bern (AIUB) and Groupe de Recherche de Geodesie Spatiale (GRGS}, which indicates that the accuracy of WHU-Grace01s has a good consistency with the previously published GRACE solutions. 展开更多
关键词 temporal gravity field model Gravity Recovery and Climate Experiment (GRACE) Dynamic integral approach K-Band Range Rate (KBRR) Satellite gravity Spherical harmonics Equivalent water height Geopotential determination
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DEVELOPMENT OF A GIS DATA MODEL WITH SPATIAL,TEMPORAL AND ATTRIBUTE COMPONENTS BASED ON OBJECT-ORIENTED APPROACH 被引量:2
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作者 SHI Wenzhong ZHANG Minwen 《Geo-Spatial Information Science》 2000年第1期17-23,共7页
This paper presents a conceptual data model, the STA-model, for handling spatial, temporal and attribute aspects of objects in GIS. The model is developed on the basis of object-oriented modeling approach. This model ... This paper presents a conceptual data model, the STA-model, for handling spatial, temporal and attribute aspects of objects in GIS. The model is developed on the basis of object-oriented modeling approach. This model includes two major parts: (a) modeling the signal objects by STA-object elements, and (b) modeling relationships between STA-objects. As an example, the STA-model is applied for modeling land cover change data with spatial, temporal and attribute components. 展开更多
关键词 目标取向 GIS 数据建模 空间 时间并且属性模型
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Effects of temporal variability on HBV model calibration
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作者 Steven Reinaldo Rusli Doddi Yudianto Jin-tao Liu 《Water Science and Engineering》 EI CAS CSCD 2015年第4期291-300,共10页
This study aimed to investigate the effects of temporal variability on the optimization of the Hydrologiska ByrS.ns Vattenbalansavedlning (HBV) model, as well as the calibration performance using manual optimization... This study aimed to investigate the effects of temporal variability on the optimization of the Hydrologiska ByrS.ns Vattenbalansavedlning (HBV) model, as well as the calibration performance using manual optimization and average parameter values. By applying the HBV model to the Jiangwan Catchment, whose geological features include lots of cracks and gaps, simulations under various schemes were developed: short, medium-length, and long temporal calibrations. The results show that, with long temporal calibration, the objective function values of the Nash- Sutcliffe efficiency coefficient (NSE), relative error (RE), root mean square error (RMSE), and high flow ratio generally deliver a preferable simulation. Although NSE and RMSE are relatively stable with different temporal scales, significant improvements to RE and the high flow ratio are seen with longer temporal calibration. It is also noted that use of average parameter values does not lead to better simulation results compared with manual optimization. With medium-length temporal calibration, manual optimization delivers the best simulation results, with NSE, RE, RMSE, and the high flow ratio being 0.563 6, 0.122 3, 0.978 8, and 0.854 7, respectively; and calibration using average parameter values delivers NSE, RE, RMSE, and the high flow ratio of 0.481 1, 0.467 6, 1.021 0, and 2.784 0, respectively. Similar behavior is found with long temporal calibration, when NSE, RE, RMSE, and the high flow ratio using manual optimization are 0.525 3, -0.069 2, 1.058 0, and 0.980 0, respectively, as compared with 0.490 3, 0.224 8, 1.096 2, and 0.547 9, respectively, using average parameter values. This study shows that selection of longer periods of temooral calibration in hvdrolouical analysis delivers better simulation in general for water balance analysis. 展开更多
关键词 HBV model model calibration Jiangwan Catchment temporal variability
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Spatiotemporal model of open-pit based on 3-D deposit model
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作者 XIA Chun-lin1, ZHOU Hui1, LI Qing-yuan2, MA Zhen-li3 1. School of Geomatics, Liaoning Technical University, Fuxin 123000, China 2. State Key Laboratory for GIS Engineering, Chinese Academy of Surveying and Mapping, Beijing 100830, China 3. Yinchuan College, China University of Mining and Technology, Yinchuan 750011, China 《中国有色金属学会会刊:英文版》 CSCD 2011年第S3期616-620,共5页
A new method was put forward to make up the three-dimensional deposit model, and the spatiotemporal models of open-pit with temporal dynamics were also studied combined with the corrected models of multilevel ground s... A new method was put forward to make up the three-dimensional deposit model, and the spatiotemporal models of open-pit with temporal dynamics were also studied combined with the corrected models of multilevel ground states so as to bring the three-dimensional open-pit model at different time and its model serial formed from the evolvement into the management of temporal dimension in order to realize the spatial three-dimension and temporal dynamic for the mining management in open-pits,which makes this model easy to query and analyze 3-D information, also help surface mining replaying and stope evolution forecasting. Finally, the time-spatial model was established to show the dynamic mining on some open-pit under the windows XP and VC++ environment. 展开更多
关键词 3D model of DEPOSIT three-dimensional model MIXED model temporal model open-pit
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Long Short-Term Memory Recurrent Neural Network-Based Acoustic Model Using Connectionist Temporal Classification on a Large-Scale Training Corpus 被引量:8
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作者 Donghyun Lee Minkyu Lim +4 位作者 Hosung Park Yoseb Kang Jeong-Sik Park Gil-Jin Jang Ji-Hwan Kim 《China Communications》 SCIE CSCD 2017年第9期23-31,共9页
A Long Short-Term Memory(LSTM) Recurrent Neural Network(RNN) has driven tremendous improvements on an acoustic model based on Gaussian Mixture Model(GMM). However, these models based on a hybrid method require a force... A Long Short-Term Memory(LSTM) Recurrent Neural Network(RNN) has driven tremendous improvements on an acoustic model based on Gaussian Mixture Model(GMM). However, these models based on a hybrid method require a forced aligned Hidden Markov Model(HMM) state sequence obtained from the GMM-based acoustic model. Therefore, it requires a long computation time for training both the GMM-based acoustic model and a deep learning-based acoustic model. In order to solve this problem, an acoustic model using CTC algorithm is proposed. CTC algorithm does not require the GMM-based acoustic model because it does not use the forced aligned HMM state sequence. However, previous works on a LSTM RNN-based acoustic model using CTC used a small-scale training corpus. In this paper, the LSTM RNN-based acoustic model using CTC is trained on a large-scale training corpus and its performance is evaluated. The implemented acoustic model has a performance of 6.18% and 15.01% in terms of Word Error Rate(WER) for clean speech and noisy speech, respectively. This is similar to a performance of the acoustic model based on the hybrid method. 展开更多
关键词 acoustic model connectionisttemporal classification LARGE-SCALE trainingcorpus LONG SHORT-TERM memory recurrentneural network
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Temporal Models for Multimedia Synchronization
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作者 李明禄 《High Technology Letters》 EI CAS 1997年第2期37-41,共5页
This paper provides a survey of selection of most common existing temporal models for multimedia synchronization, which are based on CSP, CCS, path expressions, and Petri net. Multimedia refers to the integrated gener... This paper provides a survey of selection of most common existing temporal models for multimedia synchronization, which are based on CSP, CCS, path expressions, and Petri net. Multimedia refers to the integrated generation, representation, processing, storage, and dissemination of information expressed in multiple time dependent and time independent media such as data, text, graphics, images, audio, and video. Synchronization assures a temporal order of events, which is a well-studied topic in the area of operating systems, parallel programming languages, and database technology. 展开更多
关键词 MULTIMEDIA SYNCHRONIZATION temporal modelS CONCURRENT THEORY
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Enhancing Software Effort Estimation:A Hybrid Model Combining LSTM and Random Forest
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作者 Badana Mahesh Mandava Kranthi Kiran 《Journal of Harbin Institute of Technology(New Series)》 CAS 2024年第4期42-51,共10页
Effort estimation plays a crucial role in software development projects,aiding in resource allocation,project planning,and risk management.Traditional estimation techniques often struggle to provide accurate estimates... Effort estimation plays a crucial role in software development projects,aiding in resource allocation,project planning,and risk management.Traditional estimation techniques often struggle to provide accurate estimates due to the complex nature of software projects.In recent years,machine learning approaches have shown promise in improving the accuracy of effort estimation models.This study proposes a hybrid model that combines Long Short-Term Memory(LSTM)and Random Forest(RF)algorithms to enhance software effort estimation.The proposed hybrid model takes advantage of the strengths of both LSTM and RF algorithms.To evaluate the performance of the hybrid model,an extensive set of software development projects is used as the experimental dataset.The experimental results demonstrate that the proposed hybrid model outperforms traditional estimation techniques in terms of accuracy and reliability.The integration of LSTM and RF enables the model to efficiently capture temporal dependencies and non-linear interactions in the software development data.The hybrid model enhances estimation accuracy,enabling project managers and stakeholders to make more precise predictions of effort needed for upcoming software projects. 展开更多
关键词 software effort estimation hybrid model ensemble learning LSTM temporal dependencies non⁃linear relationships
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Spatial and temporal transferability of Degree-Day Model and Simplified Energy Balance Model:a case study
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作者 HuiLin Li 《Research in Cold and Arid Regions》 CSCD 2020年第2期95-103,共9页
Glacier mass balance, the difference between accumulation and ablation at the glacier surface, is the direct reflection of the local climate regime. Under global warming, the simulation of glacier mass balance at the ... Glacier mass balance, the difference between accumulation and ablation at the glacier surface, is the direct reflection of the local climate regime. Under global warming, the simulation of glacier mass balance at the regional scale has attracted increasing interests. This study selects Urumqi Glacier No. 1 as the testbed for examining the transferability in space and time of two commonly used glacier mass balance simulation models: i.e., the Degree-Day Model(DDM) and the simplified Energy Balance Model(s EBM). Four experiments were carried out for assessing both models’ temporal and spatial transferability. The results show that the spatial transferability of both the DDM and s EBM is strong, whereas the temporal transferability of the DDM is relatively weak. For all four experiments, the overall simulation effect of the s EBM is better than that of the DDM. At the zone around Equilibrium Line Altitude(ELA), the DDM performed better than the s EBM.Also, the accuracy of parameters, including the lapse rate of air temperature and vertical gradient of precipitation at the glacier surface, is of great significance for improving the spatial transferability of both models. 展开更多
关键词 DEGREE-DAY model Simplified ENERGY Balance model temporal and spatical transferability URUMQI GLACIER No.1
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Constructing a raster-based spatio-temporal hierarchical data model for marine fisheries application 被引量:2
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作者 SU Fenzhen ZHOU Chenhu ZHANG Tianyu 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2006年第1期57-63,共7页
Marine information has been increasing quickly. The traditional database technologies have disadvantages in manipulating large amounts of marine information which relates to the position in 3-D with the time. Recently... Marine information has been increasing quickly. The traditional database technologies have disadvantages in manipulating large amounts of marine information which relates to the position in 3-D with the time. Recently, greater emphasis has been placed on GIS (geographical information system)to deal with the marine information. The GIS has shown great success for terrestrial applications in the last decades, but its use in marine fields has been far more restricted. One of the main reasons is that most of the GIS systems or their data models are designed for land applications. They cannot do well with the nature of the marine environment and for the marine information. And this becomes a fundamental challenge to the traditional GIS and its data structure. This work designed a data model, the raster-based spatio-temporal hierarchical data model (RSHDM), for the marine information system, or for the knowledge discovery fi'om spatio-temporal data, which bases itself on the nature of the marine data and overcomes the shortages of the current spatio-temporal models when they are used in the field. As an experiment, the marine fishery data warehouse (FDW) for marine fishery management was set up, which was based on the RSHDM. The experiment proved that the RSHDM can do well with the data and can extract easily the aggregations that the management needs at different levels. 展开更多
关键词 marine geographical information system spatio-temporal data model knowledge discovery fishery management data warehouse
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Effect of Spatial and Temporal Scales on Habitat Suitability Modeling:A Case Study of Ommastrephes bartramii in the Northwest Pacific Ocean 被引量:2
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作者 GONG Caixia CHEN Xinjun +1 位作者 GAO Feng TIAN Siquan 《Journal of Ocean University of China》 SCIE CAS 2014年第6期1043-1053,共11页
Temporal and spatial scales play important roles in fishery ecology, and an inappropriate spatio-temporal scale may result in large errors in modeling fish distribution. The objective of this study is to evaluate the ... Temporal and spatial scales play important roles in fishery ecology, and an inappropriate spatio-temporal scale may result in large errors in modeling fish distribution. The objective of this study is to evaluate the roles of spatio-temporal scales in habitat suitability modeling, with the western stock of winter-spring cohort of neon flying squid(Ommastrephes bartramii) in the northwest Pacific Ocean as an example. In this study, the fishery-dependent data from the Chinese Mainland Squid Jigging Technical Group and sea surface temperature(SST) from remote sensing during August to October of 2003–2008 were used. We evaluated the differences in a habitat suitability index model resulting from aggregating data with 36 different spatial scales with a combination of three latitude scales(0.5°, 1° and 2°), four longitude scales(0.5°, 1°, 2° and 4°), and three temporal scales(week, fortnight, and month). The coefficients of variation(CV) of the weekly, biweekly and monthly suitability index(SI) were compared to determine which temporal and spatial scales of SI model are more precise. This study shows that the optimal temporal and spatial scales with the lowest CV are month, and 0.5° latitude and 0.5° longitude for O. bartramii in the northwest Pacific Ocean. This suitability index model developed with an optimal scale can be cost-effective in improving forecasting fishing ground and requires no excessive sampling efforts. We suggest that the uncertainty associated with spatial and temporal scales used in data aggregations needs to be considered in habitat suitability modeling. 展开更多
关键词 西北太平洋 时间尺度 空间尺度 栖息地 建模 指数模型 时空尺度 太平洋海域
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A Methodology for Estimating Leaf Area Index by Assimilating Remote Sensing Data into Crop Model Based on Temporal and Spatial Knowledge 被引量:1
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作者 ZHU Xiaohua ZHAO Yingshi FENG Xiaoming 《Chinese Geographical Science》 SCIE CSCD 2013年第5期550-561,共12页
In this paper,a methodology for Leaf Area Index(LAI) estimating was proposed by assimilating remote sensed data into crop model based on temporal and spatial knowledge.Firstly,sensitive parameters of crop model were c... In this paper,a methodology for Leaf Area Index(LAI) estimating was proposed by assimilating remote sensed data into crop model based on temporal and spatial knowledge.Firstly,sensitive parameters of crop model were calibrated by Shuffled Complex Evolution method developed at the University of Arizona(SCE-UA) optimization method based on phenological information,which is called temporal knowledge.The calibrated crop model will be used as the forecast operator.Then,the Taylor′s mean value theorem was applied to extracting spatial information from the Moderate Resolution Imaging Spectroradiometer(MODIS) multi-scale data,which was used to calibrate the LAI inversion results by A two-layer Canopy Reflectance Model(ACRM) model.The calibrated LAI result was used as the observation operator.Finally,an Ensemble Kalman Filter(EnKF) was used to assimilate MODIS data into crop model.The results showed that the method could significantly improve the estimation accuracy of LAI and the simulated curves of LAI more conform to the crop growth situation closely comparing with MODIS LAI products.The root mean square error(RMSE) of LAI calculated by assimilation is 0.9185 which is reduced by 58.7% compared with that by simulation(0.3795),and before and after assimilation the mean error is reduced by 92.6% which is from 0.3563 to 0.0265.All these experiments indicated that the methodology proposed in this paper is reasonable and accurate for estimating crop LAI. 展开更多
关键词 叶面积指数 作物模型 遥感数据 空间知识 同化 估算 MODIS数据 中分辨率成像光谱仪
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Research of storage technique for C-Temporal Relation Data Model
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作者 (Dept. of Computer & Engineering, Guangxi University of Technology, Guangxi Liuzhou 645006, China) WANG Zhi-wen (Mechanical Engineering College, Guangxi University, 530004, NanNin China )CAI Qi-xian, Wang Hu-Qi 《微计算机信息》 北大核心 2008年第9期273-275,共3页
As there is datum redundancy in tradition database and temporal database in existence and the quantities of temporal database are increasing fleetly. We put forward compress storage tactics for temporal datum which co... As there is datum redundancy in tradition database and temporal database in existence and the quantities of temporal database are increasing fleetly. We put forward compress storage tactics for temporal datum which combine compress technology in existence in order to settle datum redundancy in the course of temporal datum storage and temporal datum of slow acting domain and momentary acting domain are accessed by using each from independence clock method and mutual clock method .We also bring forward strategy of gridding storage to resolve the problems of temporal datum rising rapidly. 展开更多
关键词 temporal Relation Data model Datum redundancy Compress storage Independence clock method Mutual clock method Gridding Storage
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A Spatio-temporal Data Model for Road Network in Data Center Based on Incremental Updating in Vehicle Navigation System 被引量:1
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作者 WU Huisheng LIU Zhaoli +1 位作者 ZHANG Shuwen ZUO Xiuling 《Chinese Geographical Science》 SCIE CSCD 2011年第3期346-353,共8页
The technique of incremental updating,which can better guarantee the real-time situation of navigational map,is the developing orientation of navigational road network updating.The data center of vehicle navigation sy... The technique of incremental updating,which can better guarantee the real-time situation of navigational map,is the developing orientation of navigational road network updating.The data center of vehicle navigation system is in charge of storing incremental data,and the spatio-temporal data model for storing incremental data does affect the efficiency of the response of the data center to the requirements of incremental data from the vehicle terminal.According to the analysis on the shortcomings of several typical spatio-temporal data models used in the data center and based on the base map with overlay model,the reverse map with overlay model (RMOM) was put forward for the data center to make rapid response to incremental data request.RMOM supports the data center to store not only the current complete road network data,but also the overlays of incremental data from the time when each road network changed to the current moment.Moreover,the storage mechanism and index structure of the incremental data were designed,and the implementation algorithm of RMOM was developed.Taking navigational road network in Guangzhou City as an example,the simulation test was conducted to validate the efficiency of RMOM.Results show that the navigation database in the data center can response to the requirements of incremental data by only one query with RMOM,and costs less time.Compared with the base map with overlay model,the data center does not need to temporarily overlay incremental data with RMOM,so time-consuming of response is significantly reduced.RMOM greatly improves the efficiency of response and provides strong support for the real-time situation of navigational road network. 展开更多
关键词 时空数据模型 车辆导航系统 数据中心 道路网络 增量更新 增量数据 覆盖模型 存储机制
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