Taking hundreds of pieces of hazardous geological maps （1 ： 10 000） of Three Gorges res-ervoir area （3GR） as background, we establish regional three-dimensional （3D） geo-hazard modelusing DEM （digital elevatio...Taking hundreds of pieces of hazardous geological maps （1 ： 10 000） of Three Gorges res-ervoir area （3GR） as background, we establish regional three-dimensional （3D） geo-hazard modelusing DEM （digital elevation model） superposed surface images and geo-hazards elements. Based on landslides and other geo-hazard survey data,using improved B-REP（boundary representa-tion）entity data structure （two-body 3D data structure）, we set up 3D solid models for each hazardous bodies in each hazardous geological maps. Then we integrate the two types of 3D models with different scales from area to point, which are the regional geo-hazard 3D model and the solid models of each disaster body, in order to provide a visual processing and analysis plat-form for danger partition, stability evaluation, disaster prevention and control, early warning and command.展开更多
In this paper we propose a method to model flowers of solid shape. Based on (Ijiri et al., 2005)’s method, we separate individual flower modeling and inflorescence modeling procedures into structure and geometry mode...In this paper we propose a method to model flowers of solid shape. Based on (Ijiri et al., 2005)’s method, we separate individual flower modeling and inflorescence modeling procedures into structure and geometry modeling. We incorporate interactive editing gestures to allow the user to edit structure parameters freely onto structure diagram. Furthermore, we use free-hand sketching techniques to allow users to create and edit 3D geometrical elements freely and easily. The final step is to automatically merge all independent 3D geometrical elements into a single waterproof mesh. Our experiments show that this solid modeling approach is promising. Using our approach, novice users can create vivid flower models easily and freely. The generated flower model is waterproof. It can have applications in visualization, animation, gaming, and toys and decorations if printed out on 3D rapid prototyping devices.展开更多
In allusion to the deficient feature of product information in conceptualdesign, a framework of deficient information modeling for conceptual shape design is put forward,which includes qualitative shape modeling (a qu...In allusion to the deficient feature of product information in conceptualdesign, a framework of deficient information modeling for conceptual shape design is put forward,which includes qualitative shape modeling (a qualitative solid model), uncertain shape modeling (anuncertain relation model) and imprecise shape modeling (an imprecise region model). In theframework, the qualitative solid model is the core, which represents qualitatively (using symbols)the conceptual shapes of mechanical products. The uncertain relation model regarding domainrelations as objects and the imprecise region model regarding domains as objects are used to dealwith the uncertain and imprecise issues respectively, which arise from qualitative shape modeling orexist in product information itself.展开更多
Swept volume solid modeling has been applied to many areas such as NC machining simulation and verification, robot workspace analysis, collision detection, and CAD. But self-intersections continue to be a challenging ...Swept volume solid modeling has been applied to many areas such as NC machining simulation and verification, robot workspace analysis, collision detection, and CAD. But self-intersections continue to be a challenging problem in the boundary representation of swept volume solids. A novel algorithm is presented in this paper to trim self-intersection regions in swept volume solids modeling. This trimming algorithm consists of two major steps: (1) roughly detecting self-intersection regions by checking intersections or overlapping of the envelop profiles; (2) splitting the whole envelop surfaces of the swept volume solid into separate non-self-intersecting patches to trim global self-intersections, and to trim local self-intersections, dividing local self-intersecting regions into patches and replacing self-intersecting patches with non-self-intersecting ones. Examples show that our algorithm is efficient and robust.展开更多
In this study, a new method for conversion of solid finite element solution to beam finite element solution is developed based on the meta-modeling theory which constructs a model consistent with continuum mechanics. ...In this study, a new method for conversion of solid finite element solution to beam finite element solution is developed based on the meta-modeling theory which constructs a model consistent with continuum mechanics. The proposed method is rigorous and efficient compared to a typical conversion method which merely computes surface integration of solid element nodal stresses to obtain cross-sectional forces. The meta-modeling theory ensures the rigorousness of proposed method by defining a proper distance between beam element and solid element solutions in a function space of continuum mechanics. Results of numerical verification test that is conducted with a simple cantilever beam are used to find the proper distance function for this conversion. Time history analysis of the main tunnel structure of a real ramp tunnel is considered as a numerical example for the proposed conversion method. It is shown that cross-sectional forces are readily computed for solid element solution of the main tunnel structure when it is converted to a beam element solution using the proposed method. Further, envelopes of resultant forces which are of primary importance for the purpose of design, are developed for a given ground motion at the end.展开更多
Solid–liquid phase equilibrium data for binary(L-arabinose–water) and(D-xylose–water) systems at temperatures from(269.85–298.05) K and ternary(L-arabinose–D-xylose–water) system at temperatures of 273.85 K,278....Solid–liquid phase equilibrium data for binary(L-arabinose–water) and(D-xylose–water) systems at temperatures from(269.85–298.05) K and ternary(L-arabinose–D-xylose–water) system at temperatures of 273.85 K,278.85 K and 284.45 K were measured at atmospheric pressure.The ternary phase diagrams of the systems were constructed on the base of the measured solubility.Two pure solid phases were formed at given temperatures,including pure L-arabinose and pure D-xylose,which were con firmed and determined by the method of Schreinemakers' wet residue.At the same temperature,the crystallization region of L-arabinose was larger than D-xylose's.The acquired solubility data were then correlated using the NRTL model,Wilson model and Xu model.The calculated solubility with the three models agreed well with the experimental values.展开更多
Based on the new viewpoint of solid and gas interaction mechanics, gas leakage in a double deformable coal seam can be understood. That is, under the action of geophysical fields, the methane flow in a double deformab...Based on the new viewpoint of solid and gas interaction mechanics, gas leakage in a double deformable coal seam can be understood. That is, under the action of geophysical fields, the methane flow in a double deformable coal seam can be essentially considered to be compressible with time dependent and mixed permeation and diffusion through a pore cleat deformable heterogeneous and anisotropy medium. Based on this new viewpoint, a coupled mathematical model for coal seam deformation and gas leakage in a double coal seam was formulated and numerical simulations for gas emission from the coal seam are presented. It is found that coupled models might be closer to reality.展开更多
A polyhedral solid modeler that operates on boundary representations (B-reps) of ob- jects must derive topological information from numerical data.Due to finite precision of the com- puter,unavoidable numerical calcul...A polyhedral solid modeler that operates on boundary representations (B-reps) of ob- jects must derive topological information from numerical data.Due to finite precision of the com- puter,unavoidable numerical calculation errors may result in ambiguous or contradictory decision of topology.These effects cause existing polyhedral modelers to fail when confronted with objects that nearly align or barely intersect. Based on analysing the reasons which cause the failure of Boolean operation to fail,this paper describes an algorithm using solid integrity to carefully design each step of Boolean operation,so that valid polyhedral modeling results may be achieved.展开更多
Solid modeling with precise NURBS boundaries compliant with STEP standard represents the most promising way of designing complicated mechanical products in a CIM environment. In paral- lel to the traditional approach ...Solid modeling with precise NURBS boundaries compliant with STEP standard represents the most promising way of designing complicated mechanical products in a CIM environment. In paral- lel to the traditional approach of putting together volumetric primitives with Boolean operations, an al- ternative way of applying the wireframe and skinning techniques is under development. The latter ap- proach is easy to implement, robust and capable of handling the most sophisticated models, while suf- fers the drawbacks of low efficiency in identifying interactively the boundaries of each surface patch when the line segments are interlaced and located close to each other. This paper describes the essentials of the wireframe and skinning techniques which produce the identical product information model as a solid modeler.展开更多
In conformity with the principle of Design for Manufacture,feature-based design strate- (?)es have been developed.As the“feature”is relevant to the“macro process plan”and“macro NC programs”,obviously,“feature”...In conformity with the principle of Design for Manufacture,feature-based design strate- (?)es have been developed.As the“feature”is relevant to the“macro process plan”and“macro NC programs”,obviously,“feature”is beyond the power of conventional solid modellers.Neverthe- less,substantial breakthrough has not been made in the solid modeling field,except“feature at- taching”or“feature recognizing”methods have been taken on.In this paper,the theory, concepts,system architecture,and algorithm principles of solid modeling tool system have been represented.The practice of Feature Solid Modeling Tool System (FSMTS) developed at Huazhong University has proved that the tool may be a new foundation of Feature-Based Design.展开更多
Municipal solid waste generation is strongly linked to rising human population and expanding urban areas, with significant implications on urban metabolism as well as space and place values redefinition. Effective man...Municipal solid waste generation is strongly linked to rising human population and expanding urban areas, with significant implications on urban metabolism as well as space and place values redefinition. Effective management performance of municipal solid waste management underscores the interdisciplinarity strategies. Such knowledge and skills are paramount to uncover the sources of waste generation as well as means of waste storage, collection, recycling, transportation, handling/treatment, disposal, and monitoring. This study was conducted in Dar es Salaam city. Driven by the curiosity model of the solid waste minimization performance at source, study data was collected using focus group discussion techniques to ward-level local government officers, which was triangulated with literature and documentary review. The main themes of the FGD were situational factors (SFA) and local government by-laws (LGBY). In the FGD session, sub-themes of SFA tricked to understand how MSW minimization is related to the presence and effect of services such as land use planning, availability of landfills, solid waste transfer stations, material recovery facilities, incinerators, solid waste collection bins, solid waste trucks, solid waste management budget and solid waste collection agents. Similarly, FGD on LGBY was extended by sub-themes such as contents of the by-law, community awareness of the by-law, and by-law enforcement mechanisms. While data preparation applied an analytical hierarchy process, data analysis applied an ordinary least square (OLS) regression model for sub-criteria that explain SFA and LGBY;and OLS standard residues as variables into geographically weighted regression with a resolution of 241 × 241 meter in ArcMap v10.5. Results showed that situational factors and local government by-laws have a strong relationship with the rate of minimizing solid waste dumping in water bodies (local R square = 0.94).展开更多
In this manuscript,we propose an analytical equivalent linear viscoelastic constitutive model for fiber-reinforced composites,bypassing general computational homogenization.The method is based on the reduced-order hom...In this manuscript,we propose an analytical equivalent linear viscoelastic constitutive model for fiber-reinforced composites,bypassing general computational homogenization.The method is based on the reduced-order homogenization(ROH)approach.The ROH method typically involves solving multiple finite element problems under periodic conditions to evaluate elastic strain and eigenstrain influence functions in an‘off-line’stage,which offers substantial cost savings compared to direct computational homogenization methods.Due to the unique structure of the fibrous unit cell,“off-line”stage calculation can be eliminated by influence functions obtained analytically.Introducing the standard solid model to the ROH method enables the creation of a comprehensive analytical homogeneous viscoelastic constitutive model.This method treats fibrous composite materials as homogeneous,anisotropic viscoelastic materials,significantly reducing computational time due to its analytical nature.This approach also enables precise determination of a homogenized anisotropic relaxation modulus and accurate capture of various viscoelastic responses under different loading conditions.Three sets of numerical examples,including unit cell tests,three-point beam bending tests,and torsion tests,are given to demonstrate the predictive performance of the homogenized viscoelastic model.Furthermore,the model is validated against experimental measurements,confirming its accuracy and reliability.展开更多
In the verification of wire electrical discharge machining （EDM）, the motion and the performance of the wire-EDM system are analyzed. The maximum inclining angle of the wire is calculated. The relevant judgment meth...In the verification of wire electrical discharge machining （EDM）, the motion and the performance of the wire-EDM system are analyzed. The maximum inclining angle of the wire is calculated. The relevant judgment methods are used for the collision between the wire, the fixture, and the machining table. In the wire-EDM simulation, the generated solid model can he used to investigate programming results and to check the machining accuracy. The generation algorithm for the solid model in the simulation is solved based on Boolean operations. The wire swept volume for each cutting step is united to form the entire wire swept volume. Through Boolean subtraction between the stock model and the entire wire swept volume, the solid model in the wire-EDM simulation is generated. The method is also suitable for the wire path intersection occurred in cutting cone-shaped models. Finally, experiments are given to prove the method.展开更多
SUMMARY： Realizing the potential of geothermal energy as a cheap, green, sustainable resource to provide for the planet＇s future energy demands that a key geophysical problem be solved first： how to develop and mai...SUMMARY： Realizing the potential of geothermal energy as a cheap, green, sustainable resource to provide for the planet＇s future energy demands that a key geophysical problem be solved first： how to develop and maintain a network of multiple fluid flow pathways for the time required to deplete the heat within a given region. We present the key components for micro-scale particle-based numerical modeling of hydraulic fracture, and fluid and heat flow in geothermal reservoirs. They are based on the latest developments of ESyS-Particle--the coupling of the lattice sofid model （LSM） to simulate the nonlinear dynamics of complex solids with the lattice Boltzmann method （LBM） applied to the nonlinear dynamics of coupled fluid and heat flow in the complex solid-fluid system. The coupled LSM/LBM can be used to simulate development of fracture systems in discontinuous media, elastic stress release, fluid injection and the consequent slip at joint surfaces, and hydraulic fractur- ing; heat exchange between hot rocks and water within flow pathways created through hydraulic fracturing; and fluid flow through complex, narrow, compact and gouge- or powder-f＇flled fracture and joint systems. We demonstrate the coupled LSM/LBM to simulate the fundamental processes listed above, which are all components for the generation and sustainability of the hot-fractured rock geothermal energy fracture systems required to exploit this new green-energy resource.展开更多
3D solid models for parts with regular-form surfaces (PRFSs) are effectively generated using traditional parametric design techniques. A new model is obtained by changing some parameters defining the model. The parts ...3D solid models for parts with regular-form surfaces (PRFSs) are effectively generated using traditional parametric design techniques. A new model is obtained by changing some parameters defining the model. The parts with free-form surfaces (PFFSs), however, cannot be defined by several parameters. Usually they are defined by some geometric elements like profile curves. The traditional parametric design approaches have not easily dealt with the PFFSs. A method for generating a solid model and an engineering drawing for PFFSs is proposed in this paper: First, the new profiles are generated from input point data. Second, the profile information is extracted from the existing model. Last, the old profiles are replaced with the new profiles. This method can preserve the associative information of the existing model and automatically generate the drawing including views, dimen- sions, and annotations. The proposed method has been implemented using a commercial CAD/CAM system, Unigraphics, and API functions written in C-language, and were applied to the blades of a turbine generator. Some illustrative examples are pro- vided in order to show the effectiveness of the proposed method.展开更多
A locally resonant viscoelastic mass-spring cell is experimentally realized by a unit cell design fabricated by 3D printing.The standard linear solid model is introduced for the viscoelastic metamaterial.The complex b...A locally resonant viscoelastic mass-spring cell is experimentally realized by a unit cell design fabricated by 3D printing.The standard linear solid model is introduced for the viscoelastic metamaterial.The complex band structures of both viscoelastic unit cell and elastic cases are presented to show the effect of viscoelasticity.Both the harmonic excitation and stochastic excitation are conducted on the finite viscoelastic metamaterial in experiments.Distinct wave attenuation is found in bandgap via sweep frequency response analysis under harmonic excitation.The experiments of the metamaterial under narrow-band noise excitation demonstrate good performance of wave attenuation in bandgap.Finally,the obtained bandgaps via numerical calculation are well consistent with the frequency ranges of wave attenuation from experiments,which confirm the effectiveness of the proposed viscoelastic model.展开更多
This paper creates 3D solid model and assembly of U RJ 92-6 oil tank and analyses its strength by integrated CAD/CAE/CAM software I-D EAS. Through integrated simulation in computer, design efficiency and quality of oi...This paper creates 3D solid model and assembly of U RJ 92-6 oil tank and analyses its strength by integrated CAD/CAE/CAM software I-D EAS. Through integrated simulation in computer, design efficiency and quality of oil tank is greatly improved. Adopting integrated CAD/CAE/CAM software to carry out integrated research to equ ipment and products, we will be able to take overall analysis in aspects of 3-D solid modeling, pre-assembly and strength, etc., to realize non-paper designi ng and parallel designing. Problems can be found and settled during designing, w hich will increase designing efficiency and one-time success rate and realize o ptimum designing for products.展开更多
In order to alleviate unstable factor-caused bifurcation and reduce oscillations in traffic flow,a feedback control with consideration of time delay is designed for the solid angle model(SAM).The stability and bifurca...In order to alleviate unstable factor-caused bifurcation and reduce oscillations in traffic flow,a feedback control with consideration of time delay is designed for the solid angle model(SAM).The stability and bifurcation condition of the new SAM is derived through linear analysis and bifurcation analysis,and then accurate range of stable region is obtained.In order to explore the mechanism of the influence of multiple parameter combinations on the stability of controlled systems,a definite integral stabilization method is provided to determine the stable interval of time delay and feedback gain.Numerical simulations are explored to verify the feasibility and effectiveness of the proposed model,which also demonstrate that feedback gain and delay are two key factors to alleviate traffic congestion in the SAM.展开更多
An automatic generation method of geological cross-sections in dredging engineering based on 3D geological solid models is presented.The 3D geological models are built applying the non-uniform rational B-splines(NURBS...An automatic generation method of geological cross-sections in dredging engineering based on 3D geological solid models is presented.The 3D geological models are built applying the non-uniform rational B-splines(NURBS) technique,and a 2D profile can be calculated and generated automatically through Boolean operation to meet the demands of dredging projects.Moreover,an automatic marking method for geological attributes is put forward based on database technology,and the geological attributes include the profile name,scale,horizontal and vertical relative coordinates,geological lithology,and 2D standard lithology legend.At the same time,the automatic marking method can also provide an interactive mode for geological engineers to edit and modify the profile in the modeling system.Practical engineering applications show that the automatic generation method is a simple,flexible,fast and precise visual graphics rendering process that can create 2D standard profiles automatically and efficiently.This method also provides a convenient support tool for geological engineering digital analysis.展开更多
基金supported by the 3D Model Library of Geo-hazards in the 3GR (No. SXJC-3ZH1A7)the software development of 3D area disaster geology map in the 3GR (No. SXJC-3ZH1A6)+1 种基金survey data acquisition and geologic map CAD system in the 3GR (No. SXKY4-02)985 Platform Projects,3D modeling and space analysis system of geo-hazards and the National Natural Science Foundation of China (No. 41172300)
文摘Taking hundreds of pieces of hazardous geological maps （1 ： 10 000） of Three Gorges res-ervoir area （3GR） as background, we establish regional three-dimensional （3D） geo-hazard modelusing DEM （digital elevation model） superposed surface images and geo-hazards elements. Based on landslides and other geo-hazard survey data,using improved B-REP（boundary representa-tion）entity data structure （two-body 3D data structure）, we set up 3D solid models for each hazardous bodies in each hazardous geological maps. Then we integrate the two types of 3D models with different scales from area to point, which are the regional geo-hazard 3D model and the solid models of each disaster body, in order to provide a visual processing and analysis plat-form for danger partition, stability evaluation, disaster prevention and control, early warning and command.
基金Project supported by the Hi-Tech Research and Development Pro-gram (863) of China (Nos. 2007AA01Z311 and 2007AA04Z1A5)the Postdoctoral Science Foundation of China (No. 20070421185)the National Research Foundation for the Doctoral Program of Higher Education of China (No. 20060335114)
文摘In this paper we propose a method to model flowers of solid shape. Based on (Ijiri et al., 2005)’s method, we separate individual flower modeling and inflorescence modeling procedures into structure and geometry modeling. We incorporate interactive editing gestures to allow the user to edit structure parameters freely onto structure diagram. Furthermore, we use free-hand sketching techniques to allow users to create and edit 3D geometrical elements freely and easily. The final step is to automatically merge all independent 3D geometrical elements into a single waterproof mesh. Our experiments show that this solid modeling approach is promising. Using our approach, novice users can create vivid flower models easily and freely. The generated flower model is waterproof. It can have applications in visualization, animation, gaming, and toys and decorations if printed out on 3D rapid prototyping devices.
基金National Natural Science Foundation of China (No.59990470)
文摘In allusion to the deficient feature of product information in conceptualdesign, a framework of deficient information modeling for conceptual shape design is put forward,which includes qualitative shape modeling (a qualitative solid model), uncertain shape modeling (anuncertain relation model) and imprecise shape modeling (an imprecise region model). In theframework, the qualitative solid model is the core, which represents qualitatively (using symbols)the conceptual shapes of mechanical products. The uncertain relation model regarding domainrelations as objects and the imprecise region model regarding domains as objects are used to dealwith the uncertain and imprecise issues respectively, which arise from qualitative shape modeling orexist in product information itself.
基金Project supported by the National Natural Science Foundation of China (No. 60473106)the Hi-Tech Research and Development Program (863) of China (Nos. 2007AA01Z311 and 2007AA04Z1A5)the National Research Foundation for the Doctoral Program of Higher Education of China (No. 20060335114)
文摘Swept volume solid modeling has been applied to many areas such as NC machining simulation and verification, robot workspace analysis, collision detection, and CAD. But self-intersections continue to be a challenging problem in the boundary representation of swept volume solids. A novel algorithm is presented in this paper to trim self-intersection regions in swept volume solids modeling. This trimming algorithm consists of two major steps: (1) roughly detecting self-intersection regions by checking intersections or overlapping of the envelop profiles; (2) splitting the whole envelop surfaces of the swept volume solid into separate non-self-intersecting patches to trim global self-intersections, and to trim local self-intersections, dividing local self-intersecting regions into patches and replacing self-intersecting patches with non-self-intersecting ones. Examples show that our algorithm is efficient and robust.
文摘In this study, a new method for conversion of solid finite element solution to beam finite element solution is developed based on the meta-modeling theory which constructs a model consistent with continuum mechanics. The proposed method is rigorous and efficient compared to a typical conversion method which merely computes surface integration of solid element nodal stresses to obtain cross-sectional forces. The meta-modeling theory ensures the rigorousness of proposed method by defining a proper distance between beam element and solid element solutions in a function space of continuum mechanics. Results of numerical verification test that is conducted with a simple cantilever beam are used to find the proper distance function for this conversion. Time history analysis of the main tunnel structure of a real ramp tunnel is considered as a numerical example for the proposed conversion method. It is shown that cross-sectional forces are readily computed for solid element solution of the main tunnel structure when it is converted to a beam element solution using the proposed method. Further, envelopes of resultant forces which are of primary importance for the purpose of design, are developed for a given ground motion at the end.
基金Supported by the National Natural Science Foundation of China(21376231)
文摘Solid–liquid phase equilibrium data for binary(L-arabinose–water) and(D-xylose–water) systems at temperatures from(269.85–298.05) K and ternary(L-arabinose–D-xylose–water) system at temperatures of 273.85 K,278.85 K and 284.45 K were measured at atmospheric pressure.The ternary phase diagrams of the systems were constructed on the base of the measured solubility.Two pure solid phases were formed at given temperatures,including pure L-arabinose and pure D-xylose,which were con firmed and determined by the method of Schreinemakers' wet residue.At the same temperature,the crystallization region of L-arabinose was larger than D-xylose's.The acquired solubility data were then correlated using the NRTL model,Wilson model and Xu model.The calculated solubility with the three models agreed well with the experimental values.
文摘Based on the new viewpoint of solid and gas interaction mechanics, gas leakage in a double deformable coal seam can be understood. That is, under the action of geophysical fields, the methane flow in a double deformable coal seam can be essentially considered to be compressible with time dependent and mixed permeation and diffusion through a pore cleat deformable heterogeneous and anisotropy medium. Based on this new viewpoint, a coupled mathematical model for coal seam deformation and gas leakage in a double coal seam was formulated and numerical simulations for gas emission from the coal seam are presented. It is found that coupled models might be closer to reality.
文摘A polyhedral solid modeler that operates on boundary representations (B-reps) of ob- jects must derive topological information from numerical data.Due to finite precision of the com- puter,unavoidable numerical calculation errors may result in ambiguous or contradictory decision of topology.These effects cause existing polyhedral modelers to fail when confronted with objects that nearly align or barely intersect. Based on analysing the reasons which cause the failure of Boolean operation to fail,this paper describes an algorithm using solid integrity to carefully design each step of Boolean operation,so that valid polyhedral modeling results may be achieved.
文摘Solid modeling with precise NURBS boundaries compliant with STEP standard represents the most promising way of designing complicated mechanical products in a CIM environment. In paral- lel to the traditional approach of putting together volumetric primitives with Boolean operations, an al- ternative way of applying the wireframe and skinning techniques is under development. The latter ap- proach is easy to implement, robust and capable of handling the most sophisticated models, while suf- fers the drawbacks of low efficiency in identifying interactively the boundaries of each surface patch when the line segments are interlaced and located close to each other. This paper describes the essentials of the wireframe and skinning techniques which produce the identical product information model as a solid modeler.
文摘In conformity with the principle of Design for Manufacture,feature-based design strate- (?)es have been developed.As the“feature”is relevant to the“macro process plan”and“macro NC programs”,obviously,“feature”is beyond the power of conventional solid modellers.Neverthe- less,substantial breakthrough has not been made in the solid modeling field,except“feature at- taching”or“feature recognizing”methods have been taken on.In this paper,the theory, concepts,system architecture,and algorithm principles of solid modeling tool system have been represented.The practice of Feature Solid Modeling Tool System (FSMTS) developed at Huazhong University has proved that the tool may be a new foundation of Feature-Based Design.
文摘Municipal solid waste generation is strongly linked to rising human population and expanding urban areas, with significant implications on urban metabolism as well as space and place values redefinition. Effective management performance of municipal solid waste management underscores the interdisciplinarity strategies. Such knowledge and skills are paramount to uncover the sources of waste generation as well as means of waste storage, collection, recycling, transportation, handling/treatment, disposal, and monitoring. This study was conducted in Dar es Salaam city. Driven by the curiosity model of the solid waste minimization performance at source, study data was collected using focus group discussion techniques to ward-level local government officers, which was triangulated with literature and documentary review. The main themes of the FGD were situational factors (SFA) and local government by-laws (LGBY). In the FGD session, sub-themes of SFA tricked to understand how MSW minimization is related to the presence and effect of services such as land use planning, availability of landfills, solid waste transfer stations, material recovery facilities, incinerators, solid waste collection bins, solid waste trucks, solid waste management budget and solid waste collection agents. Similarly, FGD on LGBY was extended by sub-themes such as contents of the by-law, community awareness of the by-law, and by-law enforcement mechanisms. While data preparation applied an analytical hierarchy process, data analysis applied an ordinary least square (OLS) regression model for sub-criteria that explain SFA and LGBY;and OLS standard residues as variables into geographically weighted regression with a resolution of 241 × 241 meter in ArcMap v10.5. Results showed that situational factors and local government by-laws have a strong relationship with the rate of minimizing solid waste dumping in water bodies (local R square = 0.94).
基金support by the National Key R&D Program of China(Grant No.2023YFA1008901)the National Natural Science Foundation of China(Grant Nos.11988102,12172009)is gratefully acknowledged.
文摘In this manuscript,we propose an analytical equivalent linear viscoelastic constitutive model for fiber-reinforced composites,bypassing general computational homogenization.The method is based on the reduced-order homogenization(ROH)approach.The ROH method typically involves solving multiple finite element problems under periodic conditions to evaluate elastic strain and eigenstrain influence functions in an‘off-line’stage,which offers substantial cost savings compared to direct computational homogenization methods.Due to the unique structure of the fibrous unit cell,“off-line”stage calculation can be eliminated by influence functions obtained analytically.Introducing the standard solid model to the ROH method enables the creation of a comprehensive analytical homogeneous viscoelastic constitutive model.This method treats fibrous composite materials as homogeneous,anisotropic viscoelastic materials,significantly reducing computational time due to its analytical nature.This approach also enables precise determination of a homogenized anisotropic relaxation modulus and accurate capture of various viscoelastic responses under different loading conditions.Three sets of numerical examples,including unit cell tests,three-point beam bending tests,and torsion tests,are given to demonstrate the predictive performance of the homogenized viscoelastic model.Furthermore,the model is validated against experimental measurements,confirming its accuracy and reliability.
文摘In the verification of wire electrical discharge machining （EDM）, the motion and the performance of the wire-EDM system are analyzed. The maximum inclining angle of the wire is calculated. The relevant judgment methods are used for the collision between the wire, the fixture, and the machining table. In the wire-EDM simulation, the generated solid model can he used to investigate programming results and to check the machining accuracy. The generation algorithm for the solid model in the simulation is solved based on Boolean operations. The wire swept volume for each cutting step is united to form the entire wire swept volume. Through Boolean subtraction between the stock model and the entire wire swept volume, the solid model in the wire-EDM simulation is generated. The method is also suitable for the wire path intersection occurred in cutting cone-shaped models. Finally, experiments are given to prove the method.
文摘SUMMARY： Realizing the potential of geothermal energy as a cheap, green, sustainable resource to provide for the planet＇s future energy demands that a key geophysical problem be solved first： how to develop and maintain a network of multiple fluid flow pathways for the time required to deplete the heat within a given region. We present the key components for micro-scale particle-based numerical modeling of hydraulic fracture, and fluid and heat flow in geothermal reservoirs. They are based on the latest developments of ESyS-Particle--the coupling of the lattice sofid model （LSM） to simulate the nonlinear dynamics of complex solids with the lattice Boltzmann method （LBM） applied to the nonlinear dynamics of coupled fluid and heat flow in the complex solid-fluid system. The coupled LSM/LBM can be used to simulate development of fracture systems in discontinuous media, elastic stress release, fluid injection and the consequent slip at joint surfaces, and hydraulic fractur- ing; heat exchange between hot rocks and water within flow pathways created through hydraulic fracturing; and fluid flow through complex, narrow, compact and gouge- or powder-f＇flled fracture and joint systems. We demonstrate the coupled LSM/LBM to simulate the fundamental processes listed above, which are all components for the generation and sustainability of the hot-fractured rock geothermal energy fracture systems required to exploit this new green-energy resource.
文摘3D solid models for parts with regular-form surfaces (PRFSs) are effectively generated using traditional parametric design techniques. A new model is obtained by changing some parameters defining the model. The parts with free-form surfaces (PFFSs), however, cannot be defined by several parameters. Usually they are defined by some geometric elements like profile curves. The traditional parametric design approaches have not easily dealt with the PFFSs. A method for generating a solid model and an engineering drawing for PFFSs is proposed in this paper: First, the new profiles are generated from input point data. Second, the profile information is extracted from the existing model. Last, the old profiles are replaced with the new profiles. This method can preserve the associative information of the existing model and automatically generate the drawing including views, dimen- sions, and annotations. The proposed method has been implemented using a commercial CAD/CAM system, Unigraphics, and API functions written in C-language, and were applied to the blades of a turbine generator. Some illustrative examples are pro- vided in order to show the effectiveness of the proposed method.
基金This work is supported in part by the National Natural Science Foundation of China under Grant Nos.11632003 and 51921003in part by the National Science Fund for Distinguished Young Scholars under Grant No.11925205.
文摘A locally resonant viscoelastic mass-spring cell is experimentally realized by a unit cell design fabricated by 3D printing.The standard linear solid model is introduced for the viscoelastic metamaterial.The complex band structures of both viscoelastic unit cell and elastic cases are presented to show the effect of viscoelasticity.Both the harmonic excitation and stochastic excitation are conducted on the finite viscoelastic metamaterial in experiments.Distinct wave attenuation is found in bandgap via sweep frequency response analysis under harmonic excitation.The experiments of the metamaterial under narrow-band noise excitation demonstrate good performance of wave attenuation in bandgap.Finally,the obtained bandgaps via numerical calculation are well consistent with the frequency ranges of wave attenuation from experiments,which confirm the effectiveness of the proposed viscoelastic model.
文摘This paper creates 3D solid model and assembly of U RJ 92-6 oil tank and analyses its strength by integrated CAD/CAE/CAM software I-D EAS. Through integrated simulation in computer, design efficiency and quality of oil tank is greatly improved. Adopting integrated CAD/CAE/CAM software to carry out integrated research to equ ipment and products, we will be able to take overall analysis in aspects of 3-D solid modeling, pre-assembly and strength, etc., to realize non-paper designi ng and parallel designing. Problems can be found and settled during designing, w hich will increase designing efficiency and one-time success rate and realize o ptimum designing for products.
基金supported by the National Key Research and Development Program of China(No.2017YFE9134700)the Natural Science Foundation of Zhejiang Province,China(No.LY22G010001)+3 种基金the Program of Humanities and Social Science of Education Ministry of China(No.20YJA630008)the Ningbo Natural Science Foundation of China(Nos.2021J235 and 2021J111)the Fund of Healthy&Intelligent Kitchen Engineering Research Center of Zhejiang Provincethe K.C.Wong Magna Fund in Ningbo University,China.
文摘In order to alleviate unstable factor-caused bifurcation and reduce oscillations in traffic flow,a feedback control with consideration of time delay is designed for the solid angle model(SAM).The stability and bifurcation condition of the new SAM is derived through linear analysis and bifurcation analysis,and then accurate range of stable region is obtained.In order to explore the mechanism of the influence of multiple parameter combinations on the stability of controlled systems,a definite integral stabilization method is provided to determine the stable interval of time delay and feedback gain.Numerical simulations are explored to verify the feasibility and effectiveness of the proposed model,which also demonstrate that feedback gain and delay are two key factors to alleviate traffic congestion in the SAM.
基金Supported by the Science Fund for Creative Research Groups of National Natural Science Foundation of China(No.51021004)Tianjin Research Program of Application Foundation and Advanced Technology(No.12JCZDJC29200)National Key Technology R and D Program in the 12th Five-Year Plan of China(No.2011BAB10B06)
文摘An automatic generation method of geological cross-sections in dredging engineering based on 3D geological solid models is presented.The 3D geological models are built applying the non-uniform rational B-splines(NURBS) technique,and a 2D profile can be calculated and generated automatically through Boolean operation to meet the demands of dredging projects.Moreover,an automatic marking method for geological attributes is put forward based on database technology,and the geological attributes include the profile name,scale,horizontal and vertical relative coordinates,geological lithology,and 2D standard lithology legend.At the same time,the automatic marking method can also provide an interactive mode for geological engineers to edit and modify the profile in the modeling system.Practical engineering applications show that the automatic generation method is a simple,flexible,fast and precise visual graphics rendering process that can create 2D standard profiles automatically and efficiently.This method also provides a convenient support tool for geological engineering digital analysis.
