. In this article, we describe the characteristics of large-scale modeling of the theme text of this site data and important progress in recent years. Topic modeling approach has attracted wide interest in the world, .... In this article, we describe the characteristics of large-scale modeling of the theme text of this site data and important progress in recent years. Topic modeling approach has attracted wide interest in the world, and promote a number of important data mining, development of computer vision and computational biology applications, including automatic text summaries, information retrieval, information recommendation, topic detection and tracking, natural scene understanding human action recognition and gene expression analysis. The main features of the model and the corresponding theme paper focuses on the text of this site data. Data with dynamic, high-end, multi-channel and distributed structure and the structure of the model is only part of the theme before modeling. The paper discussed in the framework of the unity of the three-dimensional Markov model of four structural features of the text of this site data modeling, and analysis of distributed computing and word combination of three-dimensional modeling topics Markov model and type fuzzy systems the possibility of applications. In addition to structural modeling for this site text data, also we discuss some of the three-dimensional Markov model energy minimization of machine learning algorithms.展开更多
The problems related to agricultural structure engineering for crack simulation and reliability analysis are complicated because its variables contain wide ranges of mean and standard deviation.This paper describes an...The problems related to agricultural structure engineering for crack simulation and reliability analysis are complicated because its variables contain wide ranges of mean and standard deviation.This paper describes an integrated model to perform crack simulation and reliability analysis of a continuum structure.The structure is assumed to be under a two-dimensional plane stress and the deformation is infinitesimal.A truss structure model that has the same behaviour as a continuum structure was developed using irregular triangle truss components where each element consists of two hinges with an axial degree of freedom at both of their ends.A Monte-Carlo simulation(MCS)was adopted for the reliability analysis.If the length of one side of the irregular triangle mesh is shorter than the thickness of the structure,the slenderness associated with compressive failure needs to be examined only for the short column.For that reason,the failure criterion suitable for the equivalent truss structure model was established by checking only axial stresses acting on truss members.Since nodes of the equivalent truss structure model for the structural analysis in this study consist of hinges,development of plastic hinges that occurred during crack propagation were not considered in this model.To simulate the development of crack,truss members over allowable stresses of tension or compression among truss members with the largest amount of stress at each completed structural analysis time step were sequentially removed.Since irregular triangle meshes have an uncertainty in themselves to compare with regular meshes,the equivalent truss structure model could describe crack propagation more realistically.The failure probabilities of structures under various loads and boundary conditions had good agreement with the analytical solutions directly solved from the limit state equations expressed in the form of moments.展开更多
This paper presents a method for structured scene modeling using micro stereo vision system with large field of view. The proposed algorithm includes edge detection with Canny detector, line fitting with principle axi...This paper presents a method for structured scene modeling using micro stereo vision system with large field of view. The proposed algorithm includes edge detection with Canny detector, line fitting with principle axis based approach, finding corresponding lines using feature based matching method, and 3D line depth computation.展开更多
Pore structure is a crucial factor affecting the physical properties of porous materials,and understanding the mechanisms and laws of these effects is of great significance in the fields of geosciences and petroleum e...Pore structure is a crucial factor affecting the physical properties of porous materials,and understanding the mechanisms and laws of these effects is of great significance in the fields of geosciences and petroleum engineering.However,it remains a challenge to accurately understand and quantify the relationship between pore structures and effective properties.This paper improves a workflow to focus on investigating the effect of pore structure on physical properties.First,a hybrid modeling approach combining process-based and morphology-based methods is proposed to reconstruct 3D models with diverse pore structure types.Then,the characteristics and differences in pore structure in these models are compared.Finally,the varia-tion laws and pore-scale mechanisms of the influence of pore structure on physical properties(permeability and elasticity)are discussed based on the reconstructed models.The relationship models between pore structure parameters and perme-ability/elastic parameters in the grain packing model are established.The effect of pore structure evolution on permeability/elasticity and the microscopic mechanism in three types of morphology-based reconstruction models are explored.The influence degree of pore structure on elastic parameters(bulk modulus,shear modulus,P-wave velocity,and S-wave veloc-ity)is quantified,reaching 29.54%,51.40%,18.94%,and 23.18%,respectively.This work forms a workflow for exploring the relationship between pore structures and petrophysical properties at the microscopic scale,providing more ideas and references for understanding the complex physical properties in porous media.展开更多
Coal rock is a type of dual-porosity medium,which is composed of matrix pores and fracture-cutting matrix.They play different roles in the seepage and storage capacity of coal rock.Therefore,constructing the micropore...Coal rock is a type of dual-porosity medium,which is composed of matrix pores and fracture-cutting matrix.They play different roles in the seepage and storage capacity of coal rock.Therefore,constructing the micropore structure of coal rock is very important in the exploration and development of coalbed methane.In this study,we use a coal rock digital core and three-dimensional modeling to study the pore structure of coal rock.First,the micropore structure of coal rock is quantitatively analyzed using a two-dimensional thin-section image,and the quantitative information of the pore and fracture(cleat)structure in the coal rock is extracted.The mean value and standard deviation of the face porosity and pore radius are obtained using statistical analysis.The number of pores is determined using dichotomy and spherical random-packing methods based on compression.By combining with the results of the petrophysical analysis,the single-porosity structure model of the coal rock is obtained using a nonequal-diameter sphere to represent the pores of the coal rock.Then,an ellipsoid with an aspect ratio that is very much lesser than one is used to represent the fracture(cleat)in the coal rock,and a dual-pore structure model of the coal rock is obtained.On this basis,the relationship between the different pore aspect ratios and porosity is explored,and a fitting relationship is obtained.The results show that a nonlinear relationship exists between them.The relationship model can provide a basis for the prediction of coal rock pore structure and the pore structure parameters and provide a reference for understanding the internal structure of coalbed methane reservoirs.展开更多
Enhancement of productivity optimization is steadily gaining the priority in mining companies especially in the underground coal mining industry which faces a daunting task to balance marginal profit generation with a...Enhancement of productivity optimization is steadily gaining the priority in mining companies especially in the underground coal mining industry which faces a daunting task to balance marginal profit generation with a comparatively high cost of production, volatile market price and rapid grade variation. This paper is aimed to analyze some of the causal factors both technical and site specific which are directly or indirectly impacting the productivity of the longwall coal mining system such as downtime of equipment system in longwall panel, overloading of conveyors and bin, preventive maintenance, gas management practices and injury severity rate. Structured Equation Modelling (SEM) was used to study the causal relationships between the above-mentioned factors and mine productivity. The equipment considered for analysis included shearer, armored face conveyor, crusher, bridge stage loader, chock supports, main gate drive, gate conveyor, hydraulic pumps and crusher. SEM was applied to relate the correlations existing among these causal variables in order to assess their direct or indirect impact on mining productivity. Based on the data extracted over a period of 10 months which included the extraction of 2 longwall panels, the study revealed a significant negative causal relationship between injury severity rate (p < 0.01) and equipment downtime (p = 0.001), with mine productivity. However, preventive maintenance delay time, gas management delay time and conveyor overloading delay time were found to have an insignificant direct influence on mine productivity but indirectly modify it through a significant mediator relationship with equipment downtime. This information would assist mine management to take proper preventive measures.展开更多
Background:As is widely known,an increasing number of forest areas were managed to preserve and enhance the health of forest ecosystems.However,previous research on forest management has often overlooked the importanc...Background:As is widely known,an increasing number of forest areas were managed to preserve and enhance the health of forest ecosystems.However,previous research on forest management has often overlooked the importance of structure-based.Aims:Our objectives were to define the direction of structure-based forest management.Subsequently,we investigated the relationships between forest structure and the regeneration,growth,and mortality of trees under different thinning treatments.Ultimately,the drivers of forest structural change were explored.Methods:On the basis of 92 sites selected from northeastern China,with different recovery time (from 1 to 15years) and different thinning intensities (0–59.9%) since the last thinning.Principal component analysis (PCA)identified relationships among factors determining forest spatial structure.The structural equation model (SEM)was used to analyze the driving factors behind the changes in forest spatial structure after thinning.Results:Light thinning (0–20%trees removed) promoted forest regeneration,and heavy thinning (over 35% of trees removed) facilitated forest growth.However,only moderate thinning (20%–35%trees removed) created a reasonable spatial structure.While dead trees were clustered,and they were hardly affected by thinning intensity.Additionally,thinning intensity,recovery time,and altitude indirectly improve the spatial structure of the forest by influencing diameter at breast height (DBH) and canopy area.Conclusion:Creating larger DBH and canopy area through thinning will promote the formation of complex forest structures,which cultivates healthy and stable forests.展开更多
Elemental analysis,nuclear magnetic resonance carbon spectroscopy(^(13)C-NMR),X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FTIR)experiments were carried out to determine the existen...Elemental analysis,nuclear magnetic resonance carbon spectroscopy(^(13)C-NMR),X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FTIR)experiments were carried out to determine the existence of aromatic structure,heteroatom structure and fat structure in coal.MS(materials studio)software was used to optimize and construct a 3D molecular structure model of coal.A method for establishing a coal molecular structure model was formed,which was“determination of key structures in coal,construction of planar molecular structure model,and optimization of three-dimensional molecular structure model”.The structural differences were compared and analyzed.The results show that with the increase of coal rank,the dehydrogenation of cycloalkanes in coal is continuously enhanced,and the content of heteroatoms in the aromatic ring decreases.The heteroatoms and branch chains in the coal are reduced,and the structure is more orderly and tight.The stability of the structure is determined by theπ-πinteraction between the aromatic rings in the nonbonding energy EN.Key Stretching Energy The size of EB determines how tight the structure is.The research results provide a method and reference for the study of the molecular structure of medium and high coal ranks.展开更多
Ceramic relief mural is a contemporary landscape art that is carefully designed based on human nature,culture,and architectural wall space,combined with social customs,visual sensibility,and art.It may also become the...Ceramic relief mural is a contemporary landscape art that is carefully designed based on human nature,culture,and architectural wall space,combined with social customs,visual sensibility,and art.It may also become the main axis of ceramic art in the future.Taiwan public ceramic relief murals(PCRM)are most distinctive with the PCRM pioneered by Pan-Hsiung Chu of Meinong Kiln in 1987.In addition to breaking through the limitations of traditional public ceramic murals,Chu leveraged local culture and sensibility.The theme of art gives PCRM its unique style and innovative value throughout the Taiwan region.This study mainly analyzes and understands the design image of public ceramic murals,taking Taiwan PCRM’s design and creation as the scope,and applies STEEP analysis,that is,the social,technological,economic,ecological,and political-legal environments are analyzed as core factors;eight main important factors in the artistic design image of ceramic murals are evaluated.Then,interpretive structural modeling(ISM)is used to establish five levels,analyze the four main problems in the main core factor area and the four main target results in the affected factor area;and analyze the problem points and target points as well as their causal relationships.It is expected to sort out the relationship between these factors,obtain the hierarchical relationship of each factor,and provide a reference basis and research methods.展开更多
With the continuous advancement of education informatization,Technological Pedagogical Content Knowledge(TPACK),as a new theoretical framework,provides a novel method for measuring teachers’informatization teaching a...With the continuous advancement of education informatization,Technological Pedagogical Content Knowledge(TPACK),as a new theoretical framework,provides a novel method for measuring teachers’informatization teaching ability.This study takes normal students of English majors from three ethnic universities as the research object,collects relevant data through questionnaires,and uses structural equation modeling to conduct data analysis and empirical research to investigate the differences in the TPACK levels of these students at different grades and the structural relationships among the elements in the TPACK structure.The technological pedagogical knowledge element of the TPACK structure was not obtained by exploratory factors analysis but through path analysis and structural equation modeling,the results show that the one-dimensional core knowledge of technological knowledge(TK),content knowledge(CK),and pedagogical knowledge(PK)have a positive effect on the two-dimensional interaction knowledge of technological content knowledge(TCK)and pedagogical content knowledge(PCK);furthermore,TCK and PCK have a positive effect on TPACK;and TK,CK,and PK indirectly affect TPACK through TCK and PCK.On this basis,suggestions are provided to ethnic colleges and universities to develop the TPACK knowledge competence of normal students of English majors.展开更多
To design the control system for some homing missile so that the autopilot can transfer guidance command correctly and be robust to disturbances, such as the measurement noises and parameter variation caused by areody...To design the control system for some homing missile so that the autopilot can transfer guidance command correctly and be robust to disturbances, such as the measurement noises and parameter variation caused by areodynamic floating. The model reference adaptive control was combined with the variable structure control to design a model reference variable structure (MRVS) control system whose control structure is simple and can be realized easily. The simulation results indicate that MRVS can complete the task of transferring guidance command and suppress the distrubances effectively.展开更多
Rice metallothionein-like protein (rgMT) shows characteristics of a three-section pattern composed of two highly conserved cysteine rich (CR) domains in the terminals and a spacer without cysteine (cys) residues in th...Rice metallothionein-like protein (rgMT) shows characteristics of a three-section pattern composed of two highly conserved cysteine rich (CR) domains in the terminals and a spacer without cysteine (cys) residues in the center of the molecule. In this paper, the two CR domains and the spacer region were modeled by the distance geometry and homology methods separately. For the CR domains, twenty random models were generated for each cys combination based on the constraint conditions of CXC (C represents cys, X represents any amino acid other than cys), and CXXC motifs and a metal-sulfur chelating cluster. Four models for the N-terminal and two for C-terminal CR domain containing metal chelating structures formed by different combinations of cys were selected from 900 possible conformations. The GOR method was used to predict the secondary structure of the spacer region and its model was built by the homology method. After three parts of the protein were modeled, they were connected to form a three-dimensional structure model of rgMT. The whole conformation showed that rgMT could form two independent metal-sulfur chelating structures connected by a spacer peptide, without a structural or energy barrier for them to form two independent metal-chelating clusters just as mammalian metallothionein (MT) proteins. As all plant metallothionein-like (MT-L) proteins have the same primary structural characteristic, two CR domains connected by a spacer region, and many have the same cys arrangement pattern as rgMT, the three-dimensional structure model of rgMT will provide an important reference for the structural study of other plant MT-L proteins.展开更多
Rapid increases in Carbon dioxide(CO_(2))levels could trigger unpredictable climate change.The assessment of spatiotempor-al variation and influencing factors of CO_(2) concentration are helpful in understanding the s...Rapid increases in Carbon dioxide(CO_(2))levels could trigger unpredictable climate change.The assessment of spatiotempor-al variation and influencing factors of CO_(2) concentration are helpful in understanding the source/sink balance and supporting the formu-lation of climate policy.In this study,Greenhouse Gases Observing Satellite(GOSAT)data were used to explore the variability of CO_(2) concentrations in China from 2009 to 2020.Meteorological parameters,vegetation cover,and anthropogenic activities were combined to explain the increase in CO_(2) concentration,using pixel-based correlations and Covariance Based Structural Equation Modeling(CB-SEM)analysis.The results showed that the influence of vertical CO_(2) transport diminished with altitude,with a distinct inter-annual in-crease in CO_(2) concentrations at 17 vertical levels.Spatially,the highest values were observed in East China,whereas the lowest were observed in Northwest China.There were significant seasonal variations in CO_(2) concentration,with maximum and minimum values in spring(April)and summer(August),respectively.According to the pixel-based correlation analysis,the near-surface CO_(2) concentration was positively correlated with population(r=0.99,P<0.001),Leaf Area Index(LAI,r=0.95,P<0.001),emissions(r=0.91,P<0.001),temperature(r=0.60,P<0.05),precipitation(r=0.34,P>0.05),soil water(r=0.29,P>0.05),nightlight(r=0.28,P>0.05);and negatively correlated with wind speed(r=−0.58,P<0.05).CB-SEM analysis revealed that LAI was the most important con-trolling factor explaining CO_(2) concentration variation(total effect of 0.66),followed by emissions(0.58),temperature(0.45),precipita-tion(0.30),wind speed(−0.28),and soil water(−0.07).The model explained 93% of the increase in CO_(2) concentration.Our results provide crucial information on the patterns of CO_(2) concentrations and their driving mechanisms,which are particularly significant in the context of climate change.展开更多
As the core content of pragmatic translation teaching research,pragmatic translation skill is closely correlated with translation technique and operation field.Viewed from the current English teaching situation in col...As the core content of pragmatic translation teaching research,pragmatic translation skill is closely correlated with translation technique and operation field.Viewed from the current English teaching situation in colleges and universities,translation skill is not cultivated as an independent language competence.Moreover,its research is insufficient.On account of this,the author first gives an introduction to pragmatic translation skill and pragmatic translation skill structure model in this paper.On this basis,the author also analyzes the application of pragmatic translation skill structure model in translation teaching.展开更多
A morphologically structured model is proposed to describe the batch fermentation of lovastatin according to the growth kinetics of filamentous microorganisms. Three kinds of hyphae are considered in the model: active...A morphologically structured model is proposed to describe the batch fermentation of lovastatin according to the growth kinetics of filamentous microorganisms. Three kinds of hyphae are considered in the model: actively growing hyphae, non-growing hyphae and deactivated hyphae. Furthermore, actively growing hyphae consist of three morphological compartments: apical compartment which gives rise to hyphal tip extension; subapical compartment which is related to hyphal branching; and hyphal compartment which is only responsible for secondary metabolite formation. The kinetics of mycelial growth mechanism is summarized and applied in modeling lovastatin fermentation. A Michaelis-Menten kinetic model with substrate inhibition is proposed for product formation. As expected, the model simulations fit well with experimental data obtained either from a laboratory scale 10L fer-menter or from a pilot-plant scale fermenter.展开更多
Although human beings have come to understand and utilize coal for a very long history, no theoretical breakthrough in the study of coal structure has been made, which still needs continuous efforts of coal chemical w...Although human beings have come to understand and utilize coal for a very long history, no theoretical breakthrough in the study of coal structure has been made, which still needs continuous efforts of coal chemical workers. Based on the viewpoint of ‘vague/clear', the species classification and accurate analysis on coal were conducted by using the natural clustering all-component separation method. A more systematic and detailed coal embedded structure model theory which is suitable for coal of all ranks was developed from the previous one and a more complete theoretical system about the component and structure of coal was constructed. The whole establishment process of the theory was summarized and some of the main support data and analysis test results, including TEM, AFM, FTIR, GC/MS, MALDI/TOF/MS, DART/MSD, fractal analysis and so on were provided. The coal embedded structure theory fully considers both the identity and the particularity of all-rank coal, reflects the coal component and structure in the full range of coal rank, solves the systematic cognitive problem of coal component and structure on macro and micro level, and provides a valuable and meaningful theoretical approach for the coal processing and conversion technology.展开更多
A unified structural model for high-aspect-ratio composite wing with arbitrary cross-section is developed. Two types of lay-ups of the composite wing, namely, circumferentially uniform stiffness (CUS) configuration ...A unified structural model for high-aspect-ratio composite wing with arbitrary cross-section is developed. Two types of lay-ups of the composite wing, namely, circumferentially uniform stiffness (CUS) configuration and circumferentially asymmetric stiffness (CAS) configuration, are investigated. The present structural modeling method is validated through ANSYS FEM software for the case of a composite box beam. Then, the case of a single-cell composite wing with NACA0012 airfoil shape is considered. To investigate the aeroelastic problem of high-aspect-ratio composite wings, the linear ONERA aerodynamic model is used to model the unsteady aerodynamic loads under the case of small angle of attack. Finally, flutter speeds of the high-aspect-ratio wing with various composite ply angles are determined by using U-g method.展开更多
Faults and fractures of multiple scales are frequently induced and generated in compressional structural system. Comprehensive identification of these potential faults and fractures that cannot be distinguished direct...Faults and fractures of multiple scales are frequently induced and generated in compressional structural system. Comprehensive identification of these potential faults and fractures that cannot be distinguished directly from seismic profile of the complex structures is still an unanswered problem. Based on the compressional structural geometry and kinematics theories as well as the structural interpretation from seismic data, a set of techniques is established for the identification of potential faults and fractures in compressional structures. Firstly, three-dimensional(3D) patterns and characteristics of the faults directly interpreted from seismic profile were illustrated by 3D structural model. Then, the unfolding index maps, the principal structural curvature maps, and tectonic stress field maps were obtained from structural restoration. Moreover, potential faults and fractures in compressional structures were quantitatively identified relying on comprehensive analysis of these three maps. Successful identification of the potential faults and fractures in Mishrif limestone formation and in Asmari dolomite formation of Buzurgan anticline in Iraq demonstrates the applicability and reliability of these techniques.展开更多
Field geological work, field engineering monitoring, laboratory experiments and numerical simulation were used to study the development characteristics of pore-fracture system and hydraulic fracture of No.3 coal reser...Field geological work, field engineering monitoring, laboratory experiments and numerical simulation were used to study the development characteristics of pore-fracture system and hydraulic fracture of No.3 coal reservoir in Southern Qinshui Basin. Flow patterns of methane and water in pore-fracture system and hydraulic fracture were discussed by using limit method and average method. Based on the structure model and flow pattern of post-fracturing high-rank coal reservoir, flow patterns of methane and water were established. Results show that seepage pattern of methane in pore-fracture system is linked with pore diameter, fracture width, coal bed pressure and flow velocity. While in hydraulic fracture, it is controlled by fracture height, pressure and flow velocity. Seepage pattern of water in pore-fracture system is linked with pore diameter, fracture width and flow velocity. While in hydraulic fracture, it is controlled by fracture height and flow velocity. Pores and fractures in different sizes are linked up by ultramicroscopic fissures, micro-fissures and hydraulic fracture. In post-fracturing high-rank coal reservoir, methane has level-three flow and gets through triple medium to the wellbore; and water passes mainly through double medium to the wellbore which is level-two flow.展开更多
Uncertainty in 3D geological structure models has become a bottleneck that restricts the development and application of 3D geological modeling.In order to solve this problem during periods of accuracy assessment,error...Uncertainty in 3D geological structure models has become a bottleneck that restricts the development and application of 3D geological modeling.In order to solve this problem during periods of accuracy assessment,error detection and dynamic correction in 3D geological structure models,we have reviewed the current situation and development trends in 3D geological modeling.The main context of uncertainty in 3D geological structure models is discussed.Major research issues and a general framework system of uncertainty in 3D geological structure models are proposed.We have described in detail the integration of development practices of 3D geological modeling systems,as well as the implementation process for uncertainty evaluation in 3D geological structure models.This study has laid the basis to build theoretical and methodological systems for accuracy assessment and error correction in 3D geological models and can assist in improving 3D modeling techniques under complex geological conditions.展开更多
文摘. In this article, we describe the characteristics of large-scale modeling of the theme text of this site data and important progress in recent years. Topic modeling approach has attracted wide interest in the world, and promote a number of important data mining, development of computer vision and computational biology applications, including automatic text summaries, information retrieval, information recommendation, topic detection and tracking, natural scene understanding human action recognition and gene expression analysis. The main features of the model and the corresponding theme paper focuses on the text of this site data. Data with dynamic, high-end, multi-channel and distributed structure and the structure of the model is only part of the theme before modeling. The paper discussed in the framework of the unity of the three-dimensional Markov model of four structural features of the text of this site data modeling, and analysis of distributed computing and word combination of three-dimensional modeling topics Markov model and type fuzzy systems the possibility of applications. In addition to structural modeling for this site text data, also we discuss some of the three-dimensional Markov model energy minimization of machine learning algorithms.
文摘The problems related to agricultural structure engineering for crack simulation and reliability analysis are complicated because its variables contain wide ranges of mean and standard deviation.This paper describes an integrated model to perform crack simulation and reliability analysis of a continuum structure.The structure is assumed to be under a two-dimensional plane stress and the deformation is infinitesimal.A truss structure model that has the same behaviour as a continuum structure was developed using irregular triangle truss components where each element consists of two hinges with an axial degree of freedom at both of their ends.A Monte-Carlo simulation(MCS)was adopted for the reliability analysis.If the length of one side of the irregular triangle mesh is shorter than the thickness of the structure,the slenderness associated with compressive failure needs to be examined only for the short column.For that reason,the failure criterion suitable for the equivalent truss structure model was established by checking only axial stresses acting on truss members.Since nodes of the equivalent truss structure model for the structural analysis in this study consist of hinges,development of plastic hinges that occurred during crack propagation were not considered in this model.To simulate the development of crack,truss members over allowable stresses of tension or compression among truss members with the largest amount of stress at each completed structural analysis time step were sequentially removed.Since irregular triangle meshes have an uncertainty in themselves to compare with regular meshes,the equivalent truss structure model could describe crack propagation more realistically.The failure probabilities of structures under various loads and boundary conditions had good agreement with the analytical solutions directly solved from the limit state equations expressed in the form of moments.
文摘This paper presents a method for structured scene modeling using micro stereo vision system with large field of view. The proposed algorithm includes edge detection with Canny detector, line fitting with principle axis based approach, finding corresponding lines using feature based matching method, and 3D line depth computation.
基金supported by the National Natural Science Foundation of China(42004086,42172159)the Shale Gas Evaluation and Exploitation Key Laboratory of Sichuan Province(YSK2023007).
文摘Pore structure is a crucial factor affecting the physical properties of porous materials,and understanding the mechanisms and laws of these effects is of great significance in the fields of geosciences and petroleum engineering.However,it remains a challenge to accurately understand and quantify the relationship between pore structures and effective properties.This paper improves a workflow to focus on investigating the effect of pore structure on physical properties.First,a hybrid modeling approach combining process-based and morphology-based methods is proposed to reconstruct 3D models with diverse pore structure types.Then,the characteristics and differences in pore structure in these models are compared.Finally,the varia-tion laws and pore-scale mechanisms of the influence of pore structure on physical properties(permeability and elasticity)are discussed based on the reconstructed models.The relationship models between pore structure parameters and perme-ability/elastic parameters in the grain packing model are established.The effect of pore structure evolution on permeability/elasticity and the microscopic mechanism in three types of morphology-based reconstruction models are explored.The influence degree of pore structure on elastic parameters(bulk modulus,shear modulus,P-wave velocity,and S-wave veloc-ity)is quantified,reaching 29.54%,51.40%,18.94%,and 23.18%,respectively.This work forms a workflow for exploring the relationship between pore structures and petrophysical properties at the microscopic scale,providing more ideas and references for understanding the complex physical properties in porous media.
基金sponsored by the National Natural Science Foundation of China(No.41274129)National Science and Technology Major Project(No.2016ZX05026001-004)+2 种基金Key Research and Development Program of Sichuan Province(No.2020YFG0157)the 2018 Central Supporting Local Coconstruction Fund(No.80000-18Z0140504)the Construction and Development of Universities in 2019-Joint Support for Geophysics(Double First-Class center,80000-19Z0204).
文摘Coal rock is a type of dual-porosity medium,which is composed of matrix pores and fracture-cutting matrix.They play different roles in the seepage and storage capacity of coal rock.Therefore,constructing the micropore structure of coal rock is very important in the exploration and development of coalbed methane.In this study,we use a coal rock digital core and three-dimensional modeling to study the pore structure of coal rock.First,the micropore structure of coal rock is quantitatively analyzed using a two-dimensional thin-section image,and the quantitative information of the pore and fracture(cleat)structure in the coal rock is extracted.The mean value and standard deviation of the face porosity and pore radius are obtained using statistical analysis.The number of pores is determined using dichotomy and spherical random-packing methods based on compression.By combining with the results of the petrophysical analysis,the single-porosity structure model of the coal rock is obtained using a nonequal-diameter sphere to represent the pores of the coal rock.Then,an ellipsoid with an aspect ratio that is very much lesser than one is used to represent the fracture(cleat)in the coal rock,and a dual-pore structure model of the coal rock is obtained.On this basis,the relationship between the different pore aspect ratios and porosity is explored,and a fitting relationship is obtained.The results show that a nonlinear relationship exists between them.The relationship model can provide a basis for the prediction of coal rock pore structure and the pore structure parameters and provide a reference for understanding the internal structure of coalbed methane reservoirs.
文摘Enhancement of productivity optimization is steadily gaining the priority in mining companies especially in the underground coal mining industry which faces a daunting task to balance marginal profit generation with a comparatively high cost of production, volatile market price and rapid grade variation. This paper is aimed to analyze some of the causal factors both technical and site specific which are directly or indirectly impacting the productivity of the longwall coal mining system such as downtime of equipment system in longwall panel, overloading of conveyors and bin, preventive maintenance, gas management practices and injury severity rate. Structured Equation Modelling (SEM) was used to study the causal relationships between the above-mentioned factors and mine productivity. The equipment considered for analysis included shearer, armored face conveyor, crusher, bridge stage loader, chock supports, main gate drive, gate conveyor, hydraulic pumps and crusher. SEM was applied to relate the correlations existing among these causal variables in order to assess their direct or indirect impact on mining productivity. Based on the data extracted over a period of 10 months which included the extraction of 2 longwall panels, the study revealed a significant negative causal relationship between injury severity rate (p < 0.01) and equipment downtime (p = 0.001), with mine productivity. However, preventive maintenance delay time, gas management delay time and conveyor overloading delay time were found to have an insignificant direct influence on mine productivity but indirectly modify it through a significant mediator relationship with equipment downtime. This information would assist mine management to take proper preventive measures.
基金financially supported by the Innovation Foundation for Doctoral Program of Forestry Engineering of Northeast Forestry University,grant number:LYGC202117the China Scholarship Council(CSC),grant number:202306600046+1 种基金the Research and Development Plan of Applied Technology in Heilongjiang Province of China,grant number:GA19C006Research and Demonstration on Functional Improvement Technology of Forest Ecological Security Barrier in Heilongjiang Province,grant number:GA21C030。
文摘Background:As is widely known,an increasing number of forest areas were managed to preserve and enhance the health of forest ecosystems.However,previous research on forest management has often overlooked the importance of structure-based.Aims:Our objectives were to define the direction of structure-based forest management.Subsequently,we investigated the relationships between forest structure and the regeneration,growth,and mortality of trees under different thinning treatments.Ultimately,the drivers of forest structural change were explored.Methods:On the basis of 92 sites selected from northeastern China,with different recovery time (from 1 to 15years) and different thinning intensities (0–59.9%) since the last thinning.Principal component analysis (PCA)identified relationships among factors determining forest spatial structure.The structural equation model (SEM)was used to analyze the driving factors behind the changes in forest spatial structure after thinning.Results:Light thinning (0–20%trees removed) promoted forest regeneration,and heavy thinning (over 35% of trees removed) facilitated forest growth.However,only moderate thinning (20%–35%trees removed) created a reasonable spatial structure.While dead trees were clustered,and they were hardly affected by thinning intensity.Additionally,thinning intensity,recovery time,and altitude indirectly improve the spatial structure of the forest by influencing diameter at breast height (DBH) and canopy area.Conclusion:Creating larger DBH and canopy area through thinning will promote the formation of complex forest structures,which cultivates healthy and stable forests.
基金supported by the National Natural Science Foundation of China(41872174 and 42072189)the Program for Innovative Research Team(in Science and Technology)in the Universities of Henan Province,China(21IRTSTHN007)the Program for Innovative Research Team(in Science and Technology)of Henan Polytechnic University(T2020-4)。
文摘Elemental analysis,nuclear magnetic resonance carbon spectroscopy(^(13)C-NMR),X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FTIR)experiments were carried out to determine the existence of aromatic structure,heteroatom structure and fat structure in coal.MS(materials studio)software was used to optimize and construct a 3D molecular structure model of coal.A method for establishing a coal molecular structure model was formed,which was“determination of key structures in coal,construction of planar molecular structure model,and optimization of three-dimensional molecular structure model”.The structural differences were compared and analyzed.The results show that with the increase of coal rank,the dehydrogenation of cycloalkanes in coal is continuously enhanced,and the content of heteroatoms in the aromatic ring decreases.The heteroatoms and branch chains in the coal are reduced,and the structure is more orderly and tight.The stability of the structure is determined by theπ-πinteraction between the aromatic rings in the nonbonding energy EN.Key Stretching Energy The size of EB determines how tight the structure is.The research results provide a method and reference for the study of the molecular structure of medium and high coal ranks.
文摘Ceramic relief mural is a contemporary landscape art that is carefully designed based on human nature,culture,and architectural wall space,combined with social customs,visual sensibility,and art.It may also become the main axis of ceramic art in the future.Taiwan public ceramic relief murals(PCRM)are most distinctive with the PCRM pioneered by Pan-Hsiung Chu of Meinong Kiln in 1987.In addition to breaking through the limitations of traditional public ceramic murals,Chu leveraged local culture and sensibility.The theme of art gives PCRM its unique style and innovative value throughout the Taiwan region.This study mainly analyzes and understands the design image of public ceramic murals,taking Taiwan PCRM’s design and creation as the scope,and applies STEEP analysis,that is,the social,technological,economic,ecological,and political-legal environments are analyzed as core factors;eight main important factors in the artistic design image of ceramic murals are evaluated.Then,interpretive structural modeling(ISM)is used to establish five levels,analyze the four main problems in the main core factor area and the four main target results in the affected factor area;and analyze the problem points and target points as well as their causal relationships.It is expected to sort out the relationship between these factors,obtain the hierarchical relationship of each factor,and provide a reference basis and research methods.
文摘With the continuous advancement of education informatization,Technological Pedagogical Content Knowledge(TPACK),as a new theoretical framework,provides a novel method for measuring teachers’informatization teaching ability.This study takes normal students of English majors from three ethnic universities as the research object,collects relevant data through questionnaires,and uses structural equation modeling to conduct data analysis and empirical research to investigate the differences in the TPACK levels of these students at different grades and the structural relationships among the elements in the TPACK structure.The technological pedagogical knowledge element of the TPACK structure was not obtained by exploratory factors analysis but through path analysis and structural equation modeling,the results show that the one-dimensional core knowledge of technological knowledge(TK),content knowledge(CK),and pedagogical knowledge(PK)have a positive effect on the two-dimensional interaction knowledge of technological content knowledge(TCK)and pedagogical content knowledge(PCK);furthermore,TCK and PCK have a positive effect on TPACK;and TK,CK,and PK indirectly affect TPACK through TCK and PCK.On this basis,suggestions are provided to ethnic colleges and universities to develop the TPACK knowledge competence of normal students of English majors.
文摘To design the control system for some homing missile so that the autopilot can transfer guidance command correctly and be robust to disturbances, such as the measurement noises and parameter variation caused by areodynamic floating. The model reference adaptive control was combined with the variable structure control to design a model reference variable structure (MRVS) control system whose control structure is simple and can be realized easily. The simulation results indicate that MRVS can complete the task of transferring guidance command and suppress the distrubances effectively.
文摘Rice metallothionein-like protein (rgMT) shows characteristics of a three-section pattern composed of two highly conserved cysteine rich (CR) domains in the terminals and a spacer without cysteine (cys) residues in the center of the molecule. In this paper, the two CR domains and the spacer region were modeled by the distance geometry and homology methods separately. For the CR domains, twenty random models were generated for each cys combination based on the constraint conditions of CXC (C represents cys, X represents any amino acid other than cys), and CXXC motifs and a metal-sulfur chelating cluster. Four models for the N-terminal and two for C-terminal CR domain containing metal chelating structures formed by different combinations of cys were selected from 900 possible conformations. The GOR method was used to predict the secondary structure of the spacer region and its model was built by the homology method. After three parts of the protein were modeled, they were connected to form a three-dimensional structure model of rgMT. The whole conformation showed that rgMT could form two independent metal-sulfur chelating structures connected by a spacer peptide, without a structural or energy barrier for them to form two independent metal-chelating clusters just as mammalian metallothionein (MT) proteins. As all plant metallothionein-like (MT-L) proteins have the same primary structural characteristic, two CR domains connected by a spacer region, and many have the same cys arrangement pattern as rgMT, the three-dimensional structure model of rgMT will provide an important reference for the structural study of other plant MT-L proteins.
基金Under the auspices of National Natural Science Foundation of China(No.41871193,U1910207)Program for the Philosophy and Social Science of Shanxi Province(No.2023YJ107)。
文摘Rapid increases in Carbon dioxide(CO_(2))levels could trigger unpredictable climate change.The assessment of spatiotempor-al variation and influencing factors of CO_(2) concentration are helpful in understanding the source/sink balance and supporting the formu-lation of climate policy.In this study,Greenhouse Gases Observing Satellite(GOSAT)data were used to explore the variability of CO_(2) concentrations in China from 2009 to 2020.Meteorological parameters,vegetation cover,and anthropogenic activities were combined to explain the increase in CO_(2) concentration,using pixel-based correlations and Covariance Based Structural Equation Modeling(CB-SEM)analysis.The results showed that the influence of vertical CO_(2) transport diminished with altitude,with a distinct inter-annual in-crease in CO_(2) concentrations at 17 vertical levels.Spatially,the highest values were observed in East China,whereas the lowest were observed in Northwest China.There were significant seasonal variations in CO_(2) concentration,with maximum and minimum values in spring(April)and summer(August),respectively.According to the pixel-based correlation analysis,the near-surface CO_(2) concentration was positively correlated with population(r=0.99,P<0.001),Leaf Area Index(LAI,r=0.95,P<0.001),emissions(r=0.91,P<0.001),temperature(r=0.60,P<0.05),precipitation(r=0.34,P>0.05),soil water(r=0.29,P>0.05),nightlight(r=0.28,P>0.05);and negatively correlated with wind speed(r=−0.58,P<0.05).CB-SEM analysis revealed that LAI was the most important con-trolling factor explaining CO_(2) concentration variation(total effect of 0.66),followed by emissions(0.58),temperature(0.45),precipita-tion(0.30),wind speed(−0.28),and soil water(−0.07).The model explained 93% of the increase in CO_(2) concentration.Our results provide crucial information on the patterns of CO_(2) concentrations and their driving mechanisms,which are particularly significant in the context of climate change.
文摘As the core content of pragmatic translation teaching research,pragmatic translation skill is closely correlated with translation technique and operation field.Viewed from the current English teaching situation in colleges and universities,translation skill is not cultivated as an independent language competence.Moreover,its research is insufficient.On account of this,the author first gives an introduction to pragmatic translation skill and pragmatic translation skill structure model in this paper.On this basis,the author also analyzes the application of pragmatic translation skill structure model in translation teaching.
文摘A morphologically structured model is proposed to describe the batch fermentation of lovastatin according to the growth kinetics of filamentous microorganisms. Three kinds of hyphae are considered in the model: actively growing hyphae, non-growing hyphae and deactivated hyphae. Furthermore, actively growing hyphae consist of three morphological compartments: apical compartment which gives rise to hyphal tip extension; subapical compartment which is related to hyphal branching; and hyphal compartment which is only responsible for secondary metabolite formation. The kinetics of mycelial growth mechanism is summarized and applied in modeling lovastatin fermentation. A Michaelis-Menten kinetic model with substrate inhibition is proposed for product formation. As expected, the model simulations fit well with experimental data obtained either from a laboratory scale 10L fer-menter or from a pilot-plant scale fermenter.
基金financial provided by the National Natural Science Foundation of China (Nos. 50474066, 50874108, 51274201, and 51674260)the Coal Joint Fund from National Natural Science Foundation of China and Shenhua Group Corporation Limited (No. U1361116)the National Basic Research Program of China (No. 2012CB214900)
文摘Although human beings have come to understand and utilize coal for a very long history, no theoretical breakthrough in the study of coal structure has been made, which still needs continuous efforts of coal chemical workers. Based on the viewpoint of ‘vague/clear', the species classification and accurate analysis on coal were conducted by using the natural clustering all-component separation method. A more systematic and detailed coal embedded structure model theory which is suitable for coal of all ranks was developed from the previous one and a more complete theoretical system about the component and structure of coal was constructed. The whole establishment process of the theory was summarized and some of the main support data and analysis test results, including TEM, AFM, FTIR, GC/MS, MALDI/TOF/MS, DART/MSD, fractal analysis and so on were provided. The coal embedded structure theory fully considers both the identity and the particularity of all-rank coal, reflects the coal component and structure in the full range of coal rank, solves the systematic cognitive problem of coal component and structure on macro and micro level, and provides a valuable and meaningful theoretical approach for the coal processing and conversion technology.
文摘A unified structural model for high-aspect-ratio composite wing with arbitrary cross-section is developed. Two types of lay-ups of the composite wing, namely, circumferentially uniform stiffness (CUS) configuration and circumferentially asymmetric stiffness (CAS) configuration, are investigated. The present structural modeling method is validated through ANSYS FEM software for the case of a composite box beam. Then, the case of a single-cell composite wing with NACA0012 airfoil shape is considered. To investigate the aeroelastic problem of high-aspect-ratio composite wings, the linear ONERA aerodynamic model is used to model the unsteady aerodynamic loads under the case of small angle of attack. Finally, flutter speeds of the high-aspect-ratio wing with various composite ply angles are determined by using U-g method.
基金Project(2014CB239205)supported by the National Basic Research Program of ChinaProject(20011ZX05030-005-003)supported by the National Science and Technology Major Project of China
文摘Faults and fractures of multiple scales are frequently induced and generated in compressional structural system. Comprehensive identification of these potential faults and fractures that cannot be distinguished directly from seismic profile of the complex structures is still an unanswered problem. Based on the compressional structural geometry and kinematics theories as well as the structural interpretation from seismic data, a set of techniques is established for the identification of potential faults and fractures in compressional structures. Firstly, three-dimensional(3D) patterns and characteristics of the faults directly interpreted from seismic profile were illustrated by 3D structural model. Then, the unfolding index maps, the principal structural curvature maps, and tectonic stress field maps were obtained from structural restoration. Moreover, potential faults and fractures in compressional structures were quantitatively identified relying on comprehensive analysis of these three maps. Successful identification of the potential faults and fractures in Mishrif limestone formation and in Asmari dolomite formation of Buzurgan anticline in Iraq demonstrates the applicability and reliability of these techniques.
基金Projects(41330638,41272154)supported by the National Natural Science Foundation of ChinaProject supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),ChinaProject(2014M551705)supported by the China Postdoctoral Science Foundation
文摘Field geological work, field engineering monitoring, laboratory experiments and numerical simulation were used to study the development characteristics of pore-fracture system and hydraulic fracture of No.3 coal reservoir in Southern Qinshui Basin. Flow patterns of methane and water in pore-fracture system and hydraulic fracture were discussed by using limit method and average method. Based on the structure model and flow pattern of post-fracturing high-rank coal reservoir, flow patterns of methane and water were established. Results show that seepage pattern of methane in pore-fracture system is linked with pore diameter, fracture width, coal bed pressure and flow velocity. While in hydraulic fracture, it is controlled by fracture height, pressure and flow velocity. Seepage pattern of water in pore-fracture system is linked with pore diameter, fracture width and flow velocity. While in hydraulic fracture, it is controlled by fracture height and flow velocity. Pores and fractures in different sizes are linked up by ultramicroscopic fissures, micro-fissures and hydraulic fracture. In post-fracturing high-rank coal reservoir, methane has level-three flow and gets through triple medium to the wellbore; and water passes mainly through double medium to the wellbore which is level-two flow.
基金provided by the Talent Training Project of the National Natural Science Foundation of China (No.J0730534)the National Natural Science Foundation of China (No.40902093)+1 种基金the Morning Light Plan of the Shanghai Educational Development Foundation (No.2007CG34)the Open Foundation of the Shanghai Key Laboratory of Urbanization and Ecological Restoration (No.200803)
文摘Uncertainty in 3D geological structure models has become a bottleneck that restricts the development and application of 3D geological modeling.In order to solve this problem during periods of accuracy assessment,error detection and dynamic correction in 3D geological structure models,we have reviewed the current situation and development trends in 3D geological modeling.The main context of uncertainty in 3D geological structure models is discussed.Major research issues and a general framework system of uncertainty in 3D geological structure models are proposed.We have described in detail the integration of development practices of 3D geological modeling systems,as well as the implementation process for uncertainty evaluation in 3D geological structure models.This study has laid the basis to build theoretical and methodological systems for accuracy assessment and error correction in 3D geological models and can assist in improving 3D modeling techniques under complex geological conditions.