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Space truss construction modeling based on on-orbit assembly motion feature 被引量:2
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作者 Changjie ZHAO Weizhong GUO +3 位作者 Meng CHEN Jiaxing HU Youcheng HAN Rongfu LIN 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2024年第3期365-379,共15页
More space truss construction has been planned to develop and utilize space resources.These trusses are designed in the way of large-scale,complex,modular,and on-orbit assembly.To meet the upcoming challenge of large-... More space truss construction has been planned to develop and utilize space resources.These trusses are designed in the way of large-scale,complex,modular,and on-orbit assembly.To meet the upcoming challenge of large-scale space infrastructure construction,it is necessary to study space truss automation design and robotic construction.This paper proposes an ordinal finite screw adjacency matrix model(OFSAMM),focusing on the relationship between assembly motions,to express and compute a space truss structure.In this model,a space truss is abstracted as a set of ordered assembly motions,each of which is recorded as a finite screw as the basic element of the truss and its assembly.The operation of truss transformation is also derived under this model.Therefore,the truss configuration,the assembly sequence,the truss sub-assembly,the truss components,and the on-orbit assembly task can be expressed and calculated in a unified model,which is calculated and stores the truss topology and assembly with the minimum storage cost.At the end of this paper,we introduce how to synthesize and optimize space truss design through two cases.The study will help to improve design efficiency.Furthermore,it provides a theoretical basis for the automatic construction of space truss structures,especially in the next stage. 展开更多
关键词 Adjacency matrix Finite screw On-orbit construction modeling Space applications Space trusses Topology design
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Exploration of the Construction and Path Selection of the Deep Integration Model of Industry-Education in Universities
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作者 Yufei Zhang Chang Yu 《Journal of Contemporary Educational Research》 2024年第3期187-192,共6页
Against the backdrop of continuous development in the field of education,universities are encouraged to innovate their talent cultivation systems and objectives.The deep integration of industry and education has emerg... Against the backdrop of continuous development in the field of education,universities are encouraged to innovate their talent cultivation systems and objectives.The deep integration of industry and education has emerged as an effective strategy,aligning with the basic requirements of the new engineering education initiative and exerting a positive impact on socioeconomic development.However,an analysis of the current state of industry-education integration in universities reveals several issues that require optimization,affecting the ultimate effectiveness of integration.To optimize this phenomenon and achieve high-quality development,universities need to further explore the construction of a deep integration model of industry and education,adhering to corresponding principles to form a comprehensive system.On this basis,pathways for deep industry-education integration can be summarized. 展开更多
关键词 UNIVERSITIES Industry-education integration Deep integration construction model PATHWAYS
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3D Model Construction and Ecological Environment Investigation on a Regional Scale Using UAV Remote Sensing
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作者 Chao Chen Yankun Chen +7 位作者 Haohai Jin Li Chen Zhisong Liu Haozhe Sun Junchi Hong Haonan Wang Shiyu Fang Xin Zhang 《Intelligent Automation & Soft Computing》 SCIE 2023年第8期1655-1672,共18页
The acquisition of digital regional-scale information and ecological environmental data has high requirements for structural texture,spatial res-olution,and multiple parameter categories,which is challenging to achiev... The acquisition of digital regional-scale information and ecological environmental data has high requirements for structural texture,spatial res-olution,and multiple parameter categories,which is challenging to achieve using satellite remote sensing.Considering the convenient,facilitative,and flexible characteristics of UAV(unmanned air vehicle)remote sensing tech-nology,this study selects a campus as a typical research area and uses the Pegasus D2000 equipped with a D-MSPC2000 multi-spectral camera and a CAM3000 aerial camera to acquire oblique images and multi-spectral data.Using professional software,including Context Capture,ENVI,and ArcGIS,a 3D(three-dimensional)campus model,a digital orthophoto map,and multi-spectral remote sensing map drawing are realized,and the geometric accuracy of typical feature selection is evaluated.Based on a quantitative remote sensing model,the campus ecological environment assessment is performed from the perspectives of vegetation and water body.The results presented in this study could be of great significance to the scientific management and sustainable development of regional natural resources. 展开更多
关键词 Unmanned air vehicle multi-spectral camera oblique photography 3D model construction ecological environment investigation regional scale
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Large-scale complex physical modeling and precisionanalysis 被引量:6
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作者 吴满生 狄帮让 +4 位作者 魏建新 梁向豪 周翼 刘依谋 孔昭举 《Applied Geophysics》 SCIE CSCD 2014年第2期245-251,255,共8页
Large-scale 3D physical models of complex structures can be used to simulate hydrocarbon exploration areas. The high-fidelity simulation of actual structures poses challenges to model building and quality control. Suc... Large-scale 3D physical models of complex structures can be used to simulate hydrocarbon exploration areas. The high-fidelity simulation of actual structures poses challenges to model building and quality control. Such models can be used to collect wideazimuth, multi-azimuth, and full-azimuth seismic data that can be used to verify various 3D processing and interpretation methods. Faced with nonideal imaging problems owing to the extensive complex surface conditions and subsurface structures in the oil-rich foreland basins of western China, we designed and built the KS physical model based on the complex subsurface structure. This is the largest and most complex 3D physical model built to date. The physical modeling technology advancements mainly involve 1) the model design method, 2) the model casting flow, and 3) data acquisition. A 3D velocity model of the physical model was obtained for the first time, and the model building precision was quantitatively analyzed. The absolute error was less than 3 mm, which satisfies the experimental requirements. The 3D velocity model obtained from 3D measurements of the model layers is the basis for testing various imaging methods. Furthermore, the model is considered a standard in seismic physical modeling technology. 展开更多
关键词 complex structure seismic physical modeling modeling construction ACQUISITION
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Near-surface velocity model construction based on a Monte-Carlo scheme 被引量:2
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作者 杨锴 李辉 刘玉柱 《Applied Geophysics》 SCIE CSCD 2012年第4期475-482,497,共9页
In tomographic statics seismic data processing, it 1s crucial to cletermme an optimum base for a near-surface model. In this paper, we consider near-surface model base determination as a global optimum problem. Given ... In tomographic statics seismic data processing, it 1s crucial to cletermme an optimum base for a near-surface model. In this paper, we consider near-surface model base determination as a global optimum problem. Given information from uphole shooting and the first-arrival times from a surface seismic survey, we present a near-surface velocity model construction method based on a Monte-Carlo sampling scheme using a layered equivalent medium assumption. Compared with traditional least-squares first-arrival tomography, this scheme can delineate a clearer, weathering-layer base, resulting in a better implementation of damming correction. Examples using synthetic and field data are used to demonstrate the effectiveness of the proposed scheme. 展开更多
关键词 Monte Carlo sampling scheme construction of near-surface velocity model priorinformation poster probability distribution simulate annealing algorithm
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Construction of Risk Assessment Application Model of Epidemic Disease in Large-scale Pig Farms 被引量:1
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作者 谭业平 刘强 +3 位作者 胡肄农 郁达威 何孔旺 陆昌华 《Agricultural Science & Technology》 CAS 2016年第9期2124-2126,共3页
The application model of epidemic disease assessment technology for Web-based large-scale pig farm was expounded from the identification of epidemic disease risk factors, construction of risk assessment model and deve... The application model of epidemic disease assessment technology for Web-based large-scale pig farm was expounded from the identification of epidemic disease risk factors, construction of risk assessment model and development of risk assessment system. The assessed pig farm uploaded the epidemic disease risk data information through on-line answering evaluating questionnaire to get the immediate evaluation report. The model could enhance the risk communication between pig farm veterinarian, manager and veterinary experts to help farm system understand and find disease risk factors, assess and report the potential high risk items of the pig farm in the three systems of engineering epidemic disease prevention technology, biological safety and immune monitoring, and promote the improvement and perfection of epidemic disease prevention and control measures. 展开更多
关键词 Large-scale pig farm Risk assessment of epidemic disease Model construction
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Modeling of optimal control for urban freeway corridor under incident conditions 被引量:3
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作者 Jianhu ZHENG Decun DONG 《控制理论与应用(英文版)》 EI 2006年第3期252-256,共5页
Traffic control and management are effective measures to solve the problem of traffic congestion. The optimal control model for freeway corridor is developed under incident conditions, which is in the form of minimiza... Traffic control and management are effective measures to solve the problem of traffic congestion. The optimal control model for freeway corridor is developed under incident conditions, which is in the form of minimization of the sum of the square of the difference between traffic demand and capacity at each intersection and on the freeway bottleneck section. The model optimizes control parameters of phase splits at arterial intersections, off-ramp diversion rates at upstream off-ramps and on-ramp diversion rates at downstream on ramps. Finally, the objective function is discussed and it is showed that the optimal control model is simple and practical. 展开更多
关键词 FREEWAY Optimal control Model construction Traffic corridor Traffic incident
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Geometry model construction in infrared image theory simulation of buildings 被引量:1
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作者 谢鸣 李玉秀 +1 位作者 徐辉 谈和平 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2004年第3期270-274,共5页
Geometric model construction is the basis of infrared image theory simulation. Taking the construction of the geometric model of one building in Harbin as an example, this paper analyzes the theoretical groundings of ... Geometric model construction is the basis of infrared image theory simulation. Taking the construction of the geometric model of one building in Harbin as an example, this paper analyzes the theoretical groundings of simplification and principles of geometric model construction of buildings. It then discusses some particular treatment methods in calculating the radiation transfer coefficient in geometric model construction using the Monte Carlo Method. 展开更多
关键词 geometric model construction infrared image theory radiation transfer coefficient Monte Carlo Method
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Model Construct Based Enterprise Model Architecture and Its Modeling Approach
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作者 乔非 Wu +2 位作者 Qidi YAN Junwei 《High Technology Letters》 EI CAS 2002年第1期46-53,共8页
In order to support enterprise integration, a kind of model construct based enterprise model architecture and its modeling approach are studied in this paper. First, the structural makeup and internal relationships of... In order to support enterprise integration, a kind of model construct based enterprise model architecture and its modeling approach are studied in this paper. First, the structural makeup and internal relationships of enterprise model architecture are discussed. Then, the concept of reusable model construct (MC) which belongs to the control view and can help to derive other views is proposed. The modeling approach based on model construct consists of three steps, reference model architecture synthesis, enterprise model customization, system design and implementation. According to MC based modeling approach a case study with the background of one-kind-product machinery manufacturing enterprises is illustrated. It is shown that proposal model construct based enterprise model architecture and modeling approach are practical and efficient. 展开更多
关键词 Enterprise model architecture modeling Model construct Reference model
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Research on Main Problems and Solutions of Construction Model of China's “Broadband Village”
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作者 Xuefeng YUE Yunsheng WANG 《Asian Agricultural Research》 2017年第12期68-71,74,共5页
Broadband network plays an increasingly important strategic role in the development of new rural economy,society and culture.Based on the analysis of the construction of rural agricultural informatization and existing... Broadband network plays an increasingly important strategic role in the development of new rural economy,society and culture.Based on the analysis of the construction of rural agricultural informatization and existing problems in our country,this paper gives the path selection and measures of " broadband village" combined with regional characteristics to select the construction path of " broadband village",it needs to build the long term mechanism of " broadband village" investment and financing,determine the goal of the regional construction of " broadband village" and focus on promoting the development of rural informatization services. 展开更多
关键词 Broadband Village ICT Infrastructure construction model
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Countermeasures for Solving the Environmental Problems and Accelerating the Model City Construction of Xi'an
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作者 Liu Zhenxiang Song Ting Ma Longbao 《Meteorological and Environmental Research》 CAS 2014年第2期55-58,62,共5页
Through careful study, it found that the key and difficult points of affecting and restricting Xi'an to reach the model city construction standards in provincial and national levels were "urban air environment quali... Through careful study, it found that the key and difficult points of affecting and restricting Xi'an to reach the model city construction standards in provincial and national levels were "urban air environment quality standards" and "water qualification rate of urban water environment function area". In order to tackle with the weak links, highlight the important points and focus on the difficult points to strengthen scientific and technological innovation, we actively explored new ideas and ways to resolve the dilemma in meeting the two standards of model city construction, and we managed to put forward the countermeasures to resolve the dilemma through innovating system and mechanism. "Place master system" should be carded out quickly to meet the "urban air environment quality standards", while "river master system" should be implemented as soon as possible to reach the "water qualification rate of urban water environment function area". The aim of this study was to enhance the qualification rates of the indicators for model city construction to make Xi'an successfully pass the provincial and national assessment of model city construction through dealing with the weak links to accelerate the realization of becoming model environmental protection city. 展开更多
关键词 Model environmental protection city construction COUNTERMEASURES Environmental problems China
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Construction of a model of autologous blood intracerebral hemorrhage in rats with a double injection and double needle withdrawal and the characteristics of the operative technique
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作者 Siyi Yin Zhenhui Jiang 《Neural Regeneration Research》 SCIE CAS CSCD 2006年第4期355-357,共3页
BACKGROUND : Experimental animal models of intracerebral hemorrhag (ICH) are greatly needed, so the process of establishment should be ideal in hematoma formation and easy to operate. OBJECTIVE : To construct mode... BACKGROUND : Experimental animal models of intracerebral hemorrhag (ICH) are greatly needed, so the process of establishment should be ideal in hematoma formation and easy to operate. OBJECTIVE : To construct model of ICH in rats with double injection of autologous blood taken from the cut tail cut and double withdrawal of the needle (shortened as two-step injection model), and compare with those induced by single and double injections. DESIGN : A randomized controlled tria SETTING: Department of Neurology, General Hospital of Military Area Command of Chinese PLA. MATERIALS: Thirty male Wistar rats of 10 to 12 months, weighing (400±25) g, provided by the Experimental Center of Medical Animals, General Hospital of Shenyang Military Area Command of Chinese PLA, were divided randomly into 3 groups with 10 rats in each group: two-step injection group, single injection group, double injection group. METHODS : The experiment was carried out in the Department of Neurology, General Hospital of Military Area Command of Chinese PLA from March to June in 2004. Autologous blood ICH model in rats were established as follows: In the two-step injection group, 50 μL unclotted autologous blood was taken from the rat tail cut, then injected with microsyringe into the caudate nucleus, 10 μL injected at first, paused for 2 minutes, and then the rest 40 μL injected slowly and continuously within 2 minutes. After the injection, the needle was kept immovable for about 4 minutes, withdrawn 2.0 mm, again kept immovable for about 4 minute, and then removed wholly at a slow speed. In the single injection group, 50 μL unclotted tail blood was injected slowly and continuously all within 2 minutes and the needle was slowly removed;(4) In the double injection group, 10 mL blood was injected at first, paused for 2 minutes, the rest 40 μL injected evenly within 2 minutes, and then the needle was withdrawn slowly and uninterruptedly. Neurologic findings were scored in accordance with Longa's five-point scale (0-4 scores, the higher the score, the severer the neurological dysfunction). The rats were killed to remove and sections were prepared, the morphological features of hematomas were grossly observed, the maximal diameter and size of hematomas in each slice were measured with the imaging analytical system, and the volume was calculated. Meanwhile, the conveniences of the techniques were compared. MAIN OUTCOME MEASURES: The morphological features and volume of hematomas, neurologic deficit score (NDS), and the convenience of the techniques were compared. RESULTS: All the 30 rats were involved in the analysis of results without deletion. (1) Results of the morphological observation of volume of hematoma: In the two-step injection group, hematomas located in the right caudate nucleus area regularly in circular or analogously circular shape in each slice. The formation rate of hematomas in the single injection group and double injection group were lower than those in the two-step injection group [60% (6/10), 80% (8/10), 100% (10/10), P〈 0.01, 0.05]. The volume of hematomas in the single injection group and double injection group were smaller than those in the two-step injection group [(28.5±14.8), (33.4±7.4), (41.6±3.9) mm3, P〈 0.01, 0.05]. (2) NDS results: The NDS scores in the single injection group and double injection group were smaller than that in the two-step injection group (0.90±0.83, 1.30±0.78, 1.90±0.57, P〈 0.05). (3)Comparison of the convenience of the techniques: The double injection method allowed generating reproducible hematomas in rats with shortcomings that it needed autologous arterial blood from femoral artery, and precision instruments such as microinfusion pump. The two-step injection injected fresh unclotting blood taken directly from the tail cut with microsyringe into the rat brain, and it has the advantages of easy operation, no influence on the activity of thrombase, shorter duration for model establishment, and higher rate of hematoma formation, which could generate ideal and economical models of ICH. The two-step injection induced hemotoma regularly in circular or analogously circular shape in each slice, but those induced by single and double injections were mostly in strip or fusiform shapes and extending along the needle tracks or into the ventricle or subarachnoid space. CONCLUSION : The autologous blood ICH model induced by the two-step injection method is a reproducible and reliable one in regular shape, which is better than those induced by double and single injections. 展开更多
关键词 construction of a model of autologous blood intracerebral hemorrhage in rats with a double injection and double needle withdrawal and the characteristics of the operative technique ICH
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On the Construction and Development of Strategies to Stimulate Learners' Motivation Concept and Evaluation Model
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作者 Na LI Yang GAO 《International Journal of Technology Management》 2015年第3期22-24,共3页
This paper starts from the theoretical basis of constructivism and development evaluation study that learns the principles of communication, the use of educational psychology and other disciplines of knowledge. It is ... This paper starts from the theoretical basis of constructivism and development evaluation study that learns the principles of communication, the use of educational psychology and other disciplines of knowledge. It is to build a developmental evaluation and characteristics for the idea to the attention of the relevant confidence to meet and the evaluator' s expectations as of the five elements to stimulate learning motivation, build developmental evaluation principles to stimulate learning motivation of process model. Seven strategies are to stimulate and sustain the motivation of college students, while emphasizing mentor in the process of converting role as learner and developmental evaluation. Related strategies are used in the actual teaching of "Mechanical Engineering Materials" , "Graduation Design" , "Engineer Training" course, and it achieved satisfactory teaching effect, playing a role in promoting real learning and comprehensive evaluation of the development of college students. 展开更多
关键词 Developmental Evaluation Learning Motivation Model construction STRATEGY
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Knowledge Economy: Model Construction and Development Trend of Online Education
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作者 Junjie Liu Maxim Chernyaev 《Journal of Contemporary Educational Research》 2022年第1期40-46,共7页
In regard to knowledge economy,the current concept in the model construction of online education,including distance education and online learning,generally refers to a kind of network-based learning behavior,similar t... In regard to knowledge economy,the current concept in the model construction of online education,including distance education and online learning,generally refers to a kind of network-based learning behavior,similar to the concept of online training.Compared with traditional offline education methods,through the application of information technology and internet technology for content dissemination and rapid learning,online education has the characteristics of high efficiency,convenience,low threshold,and rich teaching resources.Online education covers a wide range of people,different forms of learning,and its classification methods are more diverse.Online education services are the fastest growing field of education informatization.At the moment,the most pressing problems include effectively integrating educational resources with internet technology,launching online education services and products that are highly interactive and would encourage personalized learning,increasing user stickiness,as well as avoiding trend-following and conceptualized investment. 展开更多
关键词 Knowledge economy Model construction Online education SOLOMO MOOC INTERNATIONALIZATION
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Study on Ground Deformation during Shield Tunnel Construction
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作者 Zhongkun Zhang 《Journal of Construction Research》 2021年第2期19-26,共8页
Through the systematic analysis of the ground settlement generated by the process of shield tunneling,the relationships between ground deformation and construction parameters are studied in this paper.Based on the ass... Through the systematic analysis of the ground settlement generated by the process of shield tunneling,the relationships between ground deformation and construction parameters are studied in this paper.Based on the assumption of linear small deformation,a mathematical model of the relationship between ground deformation and construction parameters is set up.The principle and method of optimization for estimating ground deformation is studied.The actual measured data are compared with the results of theoretical analysis in a case.Considering different ground formations in different construction sites with different adverse effects on surface and underground structures,the ground surface deformations caused by shield tunneling is an aimed topic in this paper.The contributions and research implications are the revealed relationships between the ground deformation and the shield tunneling parameters during construction. 展开更多
关键词 Shield tunnel Ground settlement construction parameters Mathematical model Maximum estimation Shield tunnel Ground settlement construction parameters Mathematical model Maximum estimation
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Marketing Model Analysis of Fashion Communication Based on the Visual Analysis of Neutrosophic Systems
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作者 Fangyu Ye Xiaoshu Xu +2 位作者 Yunfeng Zhang Yan Ye Jingyu Dai 《Intelligent Automation & Soft Computing》 SCIE 2023年第8期1257-1274,共18页
In order to Improvement the Neutrosophic sets as effective tools to deal with uncertain and inconsistent information.The research takes method-ology of combined single-valued neutrosophic rough set and multi-scale dec... In order to Improvement the Neutrosophic sets as effective tools to deal with uncertain and inconsistent information.The research takes method-ology of combined single-valued neutrosophic rough set and multi-scale deci-sion systems.This paper proposes the optimal scale selection and reduction algorithms based on multi-scale single-valued neutrosophic dominance rough set model.User requirements were analyzed using KJ method to construct a hierarchical model.According to the statistics of representative studies from China and the West,we found that,on the one hand,classical theory has been expanded and supplemented in fashion culture communication and market-ing.The topics are more micro-diverse,and the research methods are inspired by other disciplines;on the other hand,Chinese practice and Chinese cultural perspective need to fill the gap.The fashion content in the new fashion,however,needs to broaden its boundaries,and in addition to integrating with cultural theory and sociology,it needs to be integrated with fashion products,including product design,visual communication,image design and so on.Aesthetic communication needs to be taken into account as an important connotation,with visual communication and the communication of images as important research elements.On the whole,this research abroad inspires the development of domestic fashion culture communication and marketing research. 展开更多
关键词 Interval valued neutrosophic AHP fashion culture fashion marketing model construction
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The 5C Model of Linguistic Creativity:Construction Grammar as a Cognitive Theory of Verbal Creativity
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作者 Thomas HOFFMANN 《Journal of Foreign Languages and Cultures》 2024年第1期139-154,共16页
Creativity is a design feature of human language.This paper presents a cognitive model of verbal creativity that draws on insights from the psychological research into creativity-particularly Glaveanu's 5A model t... Creativity is a design feature of human language.This paper presents a cognitive model of verbal creativity that draws on insights from the psychological research into creativity-particularly Glaveanu's 5A model that distinguishes five crucial perspectives on a creative act(actors,audience,artefacts,actions and affordances).The paper will outline a linguistic version of this model that adopts Construction Grammar as its theoretical foundation.The resulting"5C model of constructional creativity"argues that the central elements of linguistic creativity are constructors,co-constructors,constructs,constructional blending and the constructional network. 展开更多
关键词 CREATIVITY construction grammar cognitive linguistics BLENDING 5C model of constructional creativity COGNITION constructional networks
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Data-driven modeling of power system dynamics:Challenges,state of the art,and future work
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作者 Heqing Huang Yuzhang Lin +3 位作者 Yifan Zhou Yue Zhao Peng Zhang Lingling Fan 《iEnergy》 2023年第3期200-221,共22页
With the continual deployment of power-electronics-interfaced renewable energy resources,increasing privacy concerns due to deregulation of electricity markets,and the diversification of demand-side activities,traditi... With the continual deployment of power-electronics-interfaced renewable energy resources,increasing privacy concerns due to deregulation of electricity markets,and the diversification of demand-side activities,traditional knowledge-based power system dynamic modeling methods are faced with unprecedented challenges.Data-driven modeling has been increasingly studied in recent years because of its lesser need for prior knowledge,higher capability of handling large-scale systems,and better adaptability to variations of system operating conditions.This paper discusses about the motivations and the generalized process of datadriven modeling,and provides a comprehensive overview of various state-of-the-art techniques and applications.It also comparatively presents the advantages and disadvantages of these methods and provides insight into outstanding challenges and possible research directions for the future. 展开更多
关键词 Data-driven modeling machine learning model construction parameter identification power system dynamics system identification
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Improved ecological development model for lower Yellow River floodplain,China 被引量:4
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作者 Jin-liang Zhang Yi-zi Shang +2 位作者 Ji-xiang Liu Jian Fu Meng Cui 《Water Science and Engineering》 EI CAS CSCD 2020年第4期275-285,共11页
In this study,a model for the development of the wide floodplain in the lower Yellow River Basin,in China was developed.This model includes flood control schemes using grading criteria,enables sediment deposition in p... In this study,a model for the development of the wide floodplain in the lower Yellow River Basin,in China was developed.This model includes flood control schemes using grading criteria,enables sediment deposition in partitioned zones,and allows free exchange between channel runoff and sediment.The wide floodplain located between the main channel and levees is divided into three typical regions:the tender,low,and high floodplains.Different ecological models should be applied when these floodplains are constructed.This paper describes the associated research ideas and methodology,and clarifies several key issues,including sediment prediction and regulation,land planning,land use,and a multi-dimensional framework of safeguard measures for industries on the lower Yellow River floodplain.A refined ecological development model is proposed for the lower Yellow River floodplain,and future work on ecological and sustainable development of the lower floodplain is suggested.To establish a comprehensive system integrating runoff and sediment resource regulation in the Yellow River Basin,future work should focus on runoff and sediment exchange mechanisms in the wandering lower reaches.Furthermore,it is necessary to improve theories on floodplain planning and ecological construction,and these theories should be integrated with the research findings on land development across the lower Yellow River floodplain.©2020 Hohai University.Production and hosting by Elsevier B.V.This is an open access article under the CC BY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/4.0/). 展开更多
关键词 Ecological development Lower Yellow River FLOODPLAIN SEDIMENT Eco-friendly construction model
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A new model for predicting the total tree height for stems cut-to-length by harvesters in Pinus radiata plantations 被引量:2
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作者 Chenxi Shan Huiquan Bi +3 位作者 Duncan Watt Yun Li Martin Strandgard Mohammad Reza Ghaff ariyan 《Journal of Forestry Research》 SCIE CAS CSCD 2021年第1期21-41,共21页
A new model for predicting the total tree height for harvested stems from cut-to-length(CTL)harvester data was constructed for Pinus radiata(D.Don)following a conceptual analysis of relative stem profi les,comparisons... A new model for predicting the total tree height for harvested stems from cut-to-length(CTL)harvester data was constructed for Pinus radiata(D.Don)following a conceptual analysis of relative stem profi les,comparisons of candidate models forms and extensive selections of predictor variables.Stem profi les of more than 3000 trees in a taper data set were each processed 6 times through simulated log cutting to generate the data required for this purpose.The CTL simulations not only mimicked but also covered the full range of cutting patterns of nearly 0.45×106 stems harvested during both thinning and harvesting operations.The single-equation model was estimated through the multipleequation generalized method of moments estimator to obtain effi cient and consistent parameter estimates in the presence of error correlation and heteroscedasticity that were inherent to the systematic structure of the data.The predictive performances of our new model in its linear and nonlinear form were evaluated through a leave-one-tree-out cross validation process and compared against that of the only such existing model.The evaluations and comparisons were made through benchmarking statistics both globally over the entire data space and locally within specifi c subdivisions of the data space.These statistics indicated that the nonlinear form of our model was the best and its linear form ranked second.The prediction accuracy of our nonlinear model improved when the total log length represented more than 20%of the total tree height.The poorer performance of the existing model was partly attributed to the high degree of multicollinearity among its predictor variables,which led to highly variable and unstable parameter estimates.Our new model will facilitate and widen the utilization of harvester data far beyond the current limited use for monitoring and reporting log productions in P.radiata plantations.It will also facilitate the estimation of bark thickness and help make harvester data a potential source of taper data to reduce the intensity and cost of the conventional destructive taper sampling in the fi eld.Although developed for P.radiata,the mathematical form of our new model will be applicable to other tree species for which CTL harvester data are routinely captured during thinning and harvesting operations. 展开更多
关键词 Stem profi les Cut-to-length simulations Harvester data Model construction Nonlinear multipleequation GMM estimation Benchmarking prediction accuracy
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