Taking AutoCAD2000 as platform, an algorithm for the reconstruction ofsurface from scattered data points based on VBA is presented. With this core technology customerscan be free from traditional AutoCAD as an electro...Taking AutoCAD2000 as platform, an algorithm for the reconstruction ofsurface from scattered data points based on VBA is presented. With this core technology customerscan be free from traditional AutoCAD as an electronic board and begin to create actual presentationof real-world objects. VBA is not only a very powerful tool of development, but with very simplesyntax. Associating with those solids, objects and commands of AutoCAD 2000, VBA notably simplifiesprevious complex algorithms, graphical presentations and processing, etc. Meanwhile, it can avoidappearance of complex data structure and data format in reverse design with other modeling software.Applying VBA to reverse engineering can greatly improve modeling efficiency and facilitate surfacereconstruction.展开更多
Large,3D curved electronics are a trend of the microelectronic industry due to their unique ability to conformally coexist with complex surfaces while retaining the electronic functions of 2D planar integrated circuit...Large,3D curved electronics are a trend of the microelectronic industry due to their unique ability to conformally coexist with complex surfaces while retaining the electronic functions of 2D planar integrated circuit technologies.However,these curved electronics present great challenges to the fabrication processes.Here,we propose a reconfigurable,mask-free,conformal fabrication strategy with a robot-like system,called robotized‘transfer-and-jet’printing,to assemble diverse electronic devices on complex surfaces.This novel method is a ground-breaking advance with the unique capability to integrate rigid chips,flexible electronics,and conformal circuits on complex surfaces.Critically,each process,including transfer printing,inkjet printing,and plasma treating,are mask-free,digitalized,and programmable.The robotization techniques,including measurement,surface reconstruction and localization,and path programming,break through the fundamental constraints of 2D planar microfabrication in the context of geometric shape and size.The transfer printing begins with the laser lift-off of rigid chips or flexible electronics from donor substrates,which are then transferred onto a curved surface via a dexterous robotic palm.Then the robotic electrohydrodynamic printing directly writes submicrometer structures on the curved surface.Their permutation and combination allow versatile conformal microfabrication.Finally,robotized hybrid printing is utilized to successfully fabricate a conformal heater and antenna on a spherical surface and a flexible smart sensing skin on a winged model,where the curved circuit,flexible capacitive and piezoelectric sensor arrays,and rigid digital–analog conversion chips are assembled.Robotized hybrid printing is an innovative printing technology,enabling additive,noncontact and digital microfabrication for 3D curved electronics.展开更多
Aimed at inner quality controlling for complex surface parts, an ultrasonic testing system for complex surface parts has been developed using ultrasonic NDT(Non-destructive Testing)which has features of strong penetra...Aimed at inner quality controlling for complex surface parts, an ultrasonic testing system for complex surface parts has been developed using ultrasonic NDT(Non-destructive Testing)which has features of strong penetration, well direction, high sensitivity, low cost, and harmless to people and material. The technologies of the computer, NC (Numerical control), precision mechanism, signal analysis and processing were integrated in the testing system. The system includes a PC, system software, ultrasonic data acquisition card, stepper motor drive card and five-axis precision mechanical device, etc. The software was developed using WIN98-based VC++. According to CAD data of the parts and interpolation methods, the scanning programs can be programmed. The five-axis scanning system is driven by the CNC(computer numerical control) system to control the attitude of ultrasonic probes. The system’s automatic scanning for complex surface parts, real-time acquiring ultrasonic data and automatic identifying flaw signal have been realized. This system can be used not only for testing complex surface parts, but for testing random curve parts. With fast testing speed, high sensitivity, high testing precision and high reliability, the system has a wide adaptability.展开更多
Three dimensional-digital image correlation(3 D-DIC) is a widely used optical metrology in the experimental mechanics community because of its reliability, practicality, and flexibility. Although the precision of digi...Three dimensional-digital image correlation(3 D-DIC) is a widely used optical metrology in the experimental mechanics community because of its reliability, practicality, and flexibility. Although the precision of digital image correlation(DIC) has been thoroughly studied theoretically and numerically, verification experiments have seldom been performed, especially for complex surfaces with a small field of view(FOV). In this work, the shape of a 1-yuan coin was measured using 3 D-DIC; the shape was complex due to the presence of many fine details, and the FOV was relatively small because the coin diameter was only 25 mm. During the experiment, a novel strategy for speckle production was developed: white paint was simply sprayed onto the surface. Black paint was not used; instead, taking advantage of the reflective nature of the coin surface, polarized light and a Polaroid filter were introduced, and the polarization direction was carefully adjusted, ensuring that the spray pattern was extremely thin and that high-quality speckle images with significant contrast were captured. The three-dimensional coin shape was also successfully determined for comparison using a stylus profiler. The results demonstrate that 3 D-DIC provides high precision in shape measurement even for complex surfaces with small FOV. The precision of 3 D-DIC can reach 1/7000 of the field of view, corresponding to about 6 μm in this experiment.展开更多
Complex surfaces are widely used in aerospace,energy,and national defense industries.As one of the major means of manufacturing such as complex surfaces,the multi-axis numerical control(NC)machining technique makes mu...Complex surfaces are widely used in aerospace,energy,and national defense industries.As one of the major means of manufacturing such as complex surfaces,the multi-axis numerical control(NC)machining technique makes much contribution.When the size of complex surfaces is large or the machining space is narrow,the multi-axis NC machining may not be a good choice because of its high cost and low dexterity.Robotic machining is a beneficial supplement to the NC machining.Since it has the advantages of large operating space,good dexterity,and easy to realize parallel machining,it is a promising technique to enhance the capability of traditional NC machining.However,whether it is the multi-axis NC machining or the robotic machining,owing to the complex geometric properties and strict machining requirements,high-efficiency and high-accuracy machining of complex surfaces has always been a great challenge and remains a cutting-edge problem in the current manufacturing field.In this paper,by surveying the machining of complex parts and large complex surfaces,the theory and technology of high-efficiency and high-accuracy machining of complex surfaces are reviewed thoroughly.Then,a series of typical applications are introduced to show the state-of-the-art on the machining of complex surfaces,especially the recently developed industrial software and equipment.Finally,the summary and prospect of the machining of complex surfaces are addressed.To the best of our knowledge,this may be the first attempt to systematically review the machining of complex surfaces by the multiaxis NC and robotic machining techniques,in order to promote the further research in related fields.展开更多
Because of the developed economy and lush vegetation in southern China, the following obstacles or difficulties exist in remote sensing land surface classification: 1) Diverse surface composition types;2) Undulating t...Because of the developed economy and lush vegetation in southern China, the following obstacles or difficulties exist in remote sensing land surface classification: 1) Diverse surface composition types;2) Undulating terrains;3) Small fragmented land;4) Indistinguishable shadows of surface objects. It is our top priority to clarify how to use the concept of big data (Data mining technology) and various new technologies and methods to make complex surface remote sensing information extraction technology develop in the direction of automation, refinement and intelligence. In order to achieve the above research objectives, the paper takes the Gaofen-2 satellite data produced in China as the data source, and takes the complex surface remote sensing information extraction technology as the research object, and intelligently analyzes the remote sensing information of complex surface on the basis of completing the data collection and preprocessing. The specific extraction methods are as follows: 1) extraction research on fractal texture features of Brownian motion;2) extraction research on color features;3) extraction research on vegetation index;4) research on vectors and corresponding classification. In this paper, fractal texture features, color features, vegetation features and spectral features of remote sensing images are combined to form a combination feature vector, which improves the dimension of features, and the feature vector improves the difference of remote sensing features, and it is more conducive to the classification of remote sensing features, and thus it improves the classification accuracy of remote sensing images. It is suitable for remote sensing information extraction of complex surface in southern China. This method can be extended to complex surface area in the future.展开更多
The aim of this study was to investigate the inhibitory effect of heparin/fibronectin (Hep/Fn) complexes on neointimal hyperplasia following endovascular intervention. Hep/Fn complexes were immobilized onto titanium...The aim of this study was to investigate the inhibitory effect of heparin/fibronectin (Hep/Fn) complexes on neointimal hyperplasia following endovascular intervention. Hep/Fn complexes were immobilized onto titanium (Ti) surfaces, with subsequent X-ray photoelectron spectroscopy (XPS), Toluidine Blue 0 (TBO) and immunohistochemistry methods were used to characterize surface properties. Smooth muscle cell (SMC) cultures were used to evaluate the effect of Hep/Fn complexes on SMC proliferation. Results showed that Hep/Fn complexes successfully immobilized onto Ti surfaces and resulted in an inhibition of SMC proliferation. This study suggests that Hep/Fn surface-immobilized biomaterials develop as a new generation of biomaterials to prevent neointimal hyperplasia, particularly for use in cardiovascular implants.展开更多
The crystal structure of one novel Mn(II) complex, [Mn(pmta)_3]_2[Mn(H_2O)_6]·4H_2O(1), is reported(Hpmta = 5-methyl-1-phenyl-1H-1,2,3-triazole-4-carboxylic acid). In the title compound, the asymmetric ...The crystal structure of one novel Mn(II) complex, [Mn(pmta)_3]_2[Mn(H_2O)_6]·4H_2O(1), is reported(Hpmta = 5-methyl-1-phenyl-1H-1,2,3-triazole-4-carboxylic acid). In the title compound, the asymmetric unit consists of a [Mn(pmta_)3]ˉ anion, half [Mn(H_2O)_6]^(2+) counter cation and two lattice H_2O molecules, and the intra- and intermolecular hydrogen bonds connect the complex into a supramolecular structure. The liquid-state fluorescence spectra of complex 1 have been determined. Hirshfeld surface analysis was also studied. The main intermolecular interactions in the complex are O···H and H···H contacts.展开更多
The complexation of phosphates in the quartz-metal ion-H_2O-oleate system was studied. Computer assisted calculations with the aid of the advanced program SOLGASWATER and known equilibrium constants were used to evalu...The complexation of phosphates in the quartz-metal ion-H_2O-oleate system was studied. Computer assisted calculations with the aid of the advanced program SOLGASWATER and known equilibrium constants were used to evaluate the mechanism,The calculation results revealed that in the presence of a certain amount of phosphates, metal ions adsorbed at the quartz-H_2O interface will be transferred into solution.Thus the competi- tion for metal ions between phosphates and the quartz surface leads to surface deactivation and re- duced floatability.Various distribution diagrams clearly demonstrate the change of surface complexation as a function of added phosphate concentration.The deactivation products were also evaluated.展开更多
A novel method for preparing metalllzed film has been studied.The reduction process and properties of the poly(vinyl alcohol)(PVA)were probed by several analytic means.According to the etudies,a mechanism for the poly...A novel method for preparing metalllzed film has been studied.The reduction process and properties of the poly(vinyl alcohol)(PVA)were probed by several analytic means.According to the etudies,a mechanism for the polymer surface reduction metallization was proposed and proved.展开更多
FT IR, Raman microscopy, XRD, 29 Si and 27 Al MAS NMR, were used to investigate changes in surface properties of a natural illite sample after acid base potentiometric titration. The characteristic ...FT IR, Raman microscopy, XRD, 29 Si and 27 Al MAS NMR, were used to investigate changes in surface properties of a natural illite sample after acid base potentiometric titration. The characteristic XRD lines indicated the presence of surface Al Si complexes, preferable to Al(OH) 3 precipitates. In the microscopic Raman spectra, the vibration peaks of Si O and Al O bonds diminished as a result of treatment with acid, then increased after hydroxide back titration. The varied ratio of signal intensity between IV Al and VI Al species in 27 Al MAS NMR spectra, together with the stable BET surface area after acidimetric titration, suggested that edge faces and basal planes in the layer structure of illite participated in dissolution of structural components. The combined spectroscopic evidence demonstrated that the reactions between illite surfaces and acid leaching silicic acid and aluminum ions should be considered in the model description of surface acid base properties of the aqueous illite.展开更多
A magnetic abrasive finishing process using an alternating magnetic field is proposed for the finishing of complex surfaces.In an alternating field,the periodic changes in current will cause the magnetic cluster used ...A magnetic abrasive finishing process using an alternating magnetic field is proposed for the finishing of complex surfaces.In an alternating field,the periodic changes in current will cause the magnetic cluster used as a magnetic brush to fluctuate,which will not only continuously replace the abrasive particles in contact with the workpiece,but also periodically adjust the shape of the magnetic cluster to better fit the surface of the workpiece.In this paper,the influence of a combination of alternating and static magnetic fields on the magnetic field in the finishing area is analyzed.The feasibility of this process for finishing micro-grooves is investigated.Simulations and experimental measurements show that the combination of alternating and static magnetic fields can retain the advantages of the alternating field while increasing the magnetic flux density in the finishing area.The experimental results show that the process is feasible for finishing micro-grooves,with an excellent deburring effect on the groove edges.展开更多
Spaceborne photon-counting LiDAR is significantly affected by noise,and existing denoising algorithms cannot be universally adapted to different surface types and topographies under all observation conditions.Accordin...Spaceborne photon-counting LiDAR is significantly affected by noise,and existing denoising algorithms cannot be universally adapted to different surface types and topographies under all observation conditions.Accordingly,a new denoising method is presented to extract signal photons adaptively.The method includes two steps.First,the local neighborhood radius is calculated according to photons’density,then thefirst-step denoising process is completed via photons’curvature feature based on KNN search and covariance matrix.Second,the local photonfiltering direction and threshold are obtained based on thefirst-step denoising results by RANSAC and elevation frequency histogram,and the local dense noise photons that thefirst-step cannot be identified are further eliminated.The following results are drawn:(1)experimental results on MATLAS with different topographies indicate that the average accuracy of second-step denoising exceeds 0.94,and the accuracy is effectively improves with the number of denoising times;(2)experiments on ICESat-2 under different observation conditions demonstrate that the algorithm can accurately identify signal photons in different surface types and topographies.Overall,the proposed algorithm has good adaptability and robustness for adaptive denoising of large-scale photons,and the denoising results can provide more reasonable and reliable data for sustainable urban development.展开更多
To improve the grinding quality of robotic belt grinding systems for the workpieces with complex shaped surfaces, new concepts of the dexterity grinding point and the dexterity grinding space are proposed and their ma...To improve the grinding quality of robotic belt grinding systems for the workpieces with complex shaped surfaces, new concepts of the dexterity grinding point and the dexterity grinding space are proposed and their mathematical descriptions are defined. Factors influencing the dexterity grinding space are analyzed. And a method to determine the necessary dexterity grinding space is suggested. Based on particle swarm optimization (PSO) method, a strategy to optimize the grinding robot structural dimensions and position with respect to the grinding wheel is put forward to obtain the necessary dexterity grinding space. Finally, to grind an aerial engine blade, a dedicated PPPRRR (P: prismatic R: rotary) grinding robot structural dimensions and position with respect to the grinding wheel are optimized using the above strategy. According to simulation results, if the blade is placed within the dexterity grinding space, only one gripper and one grinding machine are needed to grind its complex shaped surfaces.展开更多
The absorber is known to be vertical axisymmetric for a single-point wave energy converter (WEC). The shape of the wetted surface usually has a great influence on the absorber's hydrodynamic characteristics which a...The absorber is known to be vertical axisymmetric for a single-point wave energy converter (WEC). The shape of the wetted surface usually has a great influence on the absorber's hydrodynamic characteristics which are closely linked with the wave power conversion ability. For complex wetted surface, the hydrodynamic coefficients have been predicted traditionally by hydrodynamic software based on the BEM. However, for a systematic study of various parameters and geometries, they are too multifarious to generate so many models and data grids. This paper examines a semi-analytical method of decomposing the complex axisyrnmetric boundary into several ring-shaped and stepped surfaces based on the boundary discretization method (BDM) which overcomes the previous difficulties. In such case, by using the linear wave theory based on eigenfunction expansion matching method, the expressions of velocity potential in each domain, the added mass, radiation damping and wave excitation forces of the oscillating absorbers are obtained. The good astringency of the hydrodynamic coefficients and wave forces are obtained for various geometries when the discrete number reaches a certain value. The captured wave power for a same given draught and displacement for various geometries are calculated and compared. Numerical results show that the geometrical shape has great effect on the wave conversion performance of the absorber. For absorbers with the same outer radius and draught or displacement, the cylindrical type shows fantastic wave energy conversion ability at some given frequencies, while in the random sea wave, the parabolic and conical ones have better stabilization and applicability in wave power conversion.展开更多
During the chemical weathering of the uranium mill tailings,released uranium could be immobilized by the newly formed secondary minerals such as oxyhydroxides.A deeper understanding of the interaction between uranium ...During the chemical weathering of the uranium mill tailings,released uranium could be immobilized by the newly formed secondary minerals such as oxyhydroxides.A deeper understanding of the interaction between uranium and common oxyhydroxides under environmental conditions is necessary.In this work,uranium sorption behaviors on Al-,Mn-and Fe-oxyhydroxide minerals(boehmite,manganite,goethite,and lepidocrocite)were investigated by batch experiments.Results showed that the uranium sorption on Al-oxyhydroxide behaved significantly differently from the other three minerals.The sorption edge of the Mn-and Fe-oxyhydroxides located around pH 5,while the sorption edge of boehmite shifted about 1.5 pH unit to near neutral.The sorption isotherms of uranium on manganite,goethite and lepidocrocite at pH 5.0 could be well fitted by the Langmuir model.Instead of surface complexation,sorption on boehmite happened mainly by uranium-bearing carbonates and hydroxides precipitation as illustrated by the characterization results.Both carbonate and phosphate strongly affected the uranium sorption behavior.The removal efficiency of uranium by boehmite exceeded 98%after three sorption-desorption cycles,indicating it may be a potential material for uranium removal and recovery.展开更多
Airborne laser scanning (ALS) is a technique used to obtain Digital Surface Models (DSM) and Digital Terrain Models (DTM) efficiently, and filtering is the key procedure used to derive DTM from point clouds. Gen...Airborne laser scanning (ALS) is a technique used to obtain Digital Surface Models (DSM) and Digital Terrain Models (DTM) efficiently, and filtering is the key procedure used to derive DTM from point clouds. Generating seed points is an initial step for most filtering algorithms, whereas existing algorithms usually define a regular window size to generate seed points. This may lead to an inadequate density of seed points, and further introduce error type I, especially in steep terrain and forested areas. In this study, we propose the use of object- based analysis to derive surface complexity information from ALS datasets, which can then be used to improve seed point generation. We assume that an area is complex if it is composed of many small objects, with no buildings within the area. Using these assumptions, we propose and implement a new segmentation algorithm based on a grid index, which we call the Edge and Slope Restricted Region Growing (ESRGG) algorithm. Surface complexity information is obtained by statistical analysis of the number of objects derived by segmentation in each area. Then, for complex areas, a smaller window size is defined to generate seed points. Experimental results show that the proposed algorithm could greatly improve the filtering results in complex areas, especially in steep terrain and forested areas.展开更多
Based on observation data from urban observation stations in Nanjing and Suzhou at two heights in the roughness sublayer above the canopy and observation data at three heights in the SORPES station at the Xianlin Camp...Based on observation data from urban observation stations in Nanjing and Suzhou at two heights in the roughness sublayer above the canopy and observation data at three heights in the SORPES station at the Xianlin Campus of Nanjing University in a suburban area,the of land-atmosphere turbulent flux exchange and the energy balance over complex underlying surfaces were analyzed.The results indicated that in the roughness sublayer above the canopy,the nearsurface momentum flux,sensible heat flux,and latent heat flux increase with height,and the observation value of the surface albedo increases with height.However,the observation value of the net radiation decreases with height,thus resulting in a change in the urban surface energy budget with height.At the SORPES station in the Xianlin Campus of Nanjing University located in a hilly area,the momentum flux,sensible heat flux,and latent heat flux of the ground observation field significantly differed from those of the two heights on the tower,while the two heights on the tower were extremely close.These results indicate that the flux observation over the complex underlying surface exhibits adequate local only when it is conducted at a higher altitude above the ground.The turbulent flux observation results at a lower altitude in urban areas are underestimated,while the turbulent flux observation results near the surface produce a large deviation over the underlying hilly complex.展开更多
In this study,the surface properties and adsorption properties of the Le An River sedi- ment were modelled via surface complexation approach.The model parameters were determined based on the data of our potentiometric...In this study,the surface properties and adsorption properties of the Le An River sedi- ment were modelled via surface complexation approach.The model parameters were determined based on the data of our potentiometric titration experiments and the metal adsorption experiments with the Le An River sediment samples.Consequently,the surface complexation models for the natural sediment,in our case the Le An River sediments,which can interpret the experimental data very well were successfully established.Three typical surface complexation models that is the con- stant capacitance model,the diffuse layer model and the triple layer model,were considered in this research.This work indicated that the consistency and the interdependency among model parame- ters together with the selection of the surface adsorbed species should be emphasized.展开更多
The correlation between surface complexation at the SiO_(2)H_(2)O interface and quartz notation behavior was studied.Computer assisted calculations,using the programs SOLGASWATER,were adapted in order to con-struct di...The correlation between surface complexation at the SiO_(2)H_(2)O interface and quartz notation behavior was studied.Computer assisted calculations,using the programs SOLGASWATER,were adapted in order to con-struct distribution diagrams of surface speciation in the SiO_(2)-metal ion-H^(+) system in aqueous solutions.Equilib-rium constants for both surface and solution reactions were introduced in the composition matrix.Surface complexation,surface charge as well as notation results were compared and a good agreement was obtained.Furthermore,flotation mechanisms of quartz activation by common metal ions like Ca^(2+),Mg^(2+),Fe^(2+) are quantitatively discussed based on the surface reaction equilibrium constants.展开更多
文摘Taking AutoCAD2000 as platform, an algorithm for the reconstruction ofsurface from scattered data points based on VBA is presented. With this core technology customerscan be free from traditional AutoCAD as an electronic board and begin to create actual presentationof real-world objects. VBA is not only a very powerful tool of development, but with very simplesyntax. Associating with those solids, objects and commands of AutoCAD 2000, VBA notably simplifiesprevious complex algorithms, graphical presentations and processing, etc. Meanwhile, it can avoidappearance of complex data structure and data format in reverse design with other modeling software.Applying VBA to reverse engineering can greatly improve modeling efficiency and facilitate surfacereconstruction.
基金The authors acknowledge support from the National Nat-ural Science Foundation of China(51635007,51925503,51705179)Natural Science Foundation of Hubei Province of China(2020CFA028).
文摘Large,3D curved electronics are a trend of the microelectronic industry due to their unique ability to conformally coexist with complex surfaces while retaining the electronic functions of 2D planar integrated circuit technologies.However,these curved electronics present great challenges to the fabrication processes.Here,we propose a reconfigurable,mask-free,conformal fabrication strategy with a robot-like system,called robotized‘transfer-and-jet’printing,to assemble diverse electronic devices on complex surfaces.This novel method is a ground-breaking advance with the unique capability to integrate rigid chips,flexible electronics,and conformal circuits on complex surfaces.Critically,each process,including transfer printing,inkjet printing,and plasma treating,are mask-free,digitalized,and programmable.The robotization techniques,including measurement,surface reconstruction and localization,and path programming,break through the fundamental constraints of 2D planar microfabrication in the context of geometric shape and size.The transfer printing begins with the laser lift-off of rigid chips or flexible electronics from donor substrates,which are then transferred onto a curved surface via a dexterous robotic palm.Then the robotic electrohydrodynamic printing directly writes submicrometer structures on the curved surface.Their permutation and combination allow versatile conformal microfabrication.Finally,robotized hybrid printing is utilized to successfully fabricate a conformal heater and antenna on a spherical surface and a flexible smart sensing skin on a winged model,where the curved circuit,flexible capacitive and piezoelectric sensor arrays,and rigid digital–analog conversion chips are assembled.Robotized hybrid printing is an innovative printing technology,enabling additive,noncontact and digital microfabrication for 3D curved electronics.
文摘Aimed at inner quality controlling for complex surface parts, an ultrasonic testing system for complex surface parts has been developed using ultrasonic NDT(Non-destructive Testing)which has features of strong penetration, well direction, high sensitivity, low cost, and harmless to people and material. The technologies of the computer, NC (Numerical control), precision mechanism, signal analysis and processing were integrated in the testing system. The system includes a PC, system software, ultrasonic data acquisition card, stepper motor drive card and five-axis precision mechanical device, etc. The software was developed using WIN98-based VC++. According to CAD data of the parts and interpolation methods, the scanning programs can be programmed. The five-axis scanning system is driven by the CNC(computer numerical control) system to control the attitude of ultrasonic probes. The system’s automatic scanning for complex surface parts, real-time acquiring ultrasonic data and automatic identifying flaw signal have been realized. This system can be used not only for testing complex surface parts, but for testing random curve parts. With fast testing speed, high sensitivity, high testing precision and high reliability, the system has a wide adaptability.
基金supported by the National Natural Science Foundation of China(Grant Nos.11332010,51271174,11372300,11127201,11472266&11428206)
文摘Three dimensional-digital image correlation(3 D-DIC) is a widely used optical metrology in the experimental mechanics community because of its reliability, practicality, and flexibility. Although the precision of digital image correlation(DIC) has been thoroughly studied theoretically and numerically, verification experiments have seldom been performed, especially for complex surfaces with a small field of view(FOV). In this work, the shape of a 1-yuan coin was measured using 3 D-DIC; the shape was complex due to the presence of many fine details, and the FOV was relatively small because the coin diameter was only 25 mm. During the experiment, a novel strategy for speckle production was developed: white paint was simply sprayed onto the surface. Black paint was not used; instead, taking advantage of the reflective nature of the coin surface, polarized light and a Polaroid filter were introduced, and the polarization direction was carefully adjusted, ensuring that the spray pattern was extremely thin and that high-quality speckle images with significant contrast were captured. The three-dimensional coin shape was also successfully determined for comparison using a stylus profiler. The results demonstrate that 3 D-DIC provides high precision in shape measurement even for complex surfaces with small FOV. The precision of 3 D-DIC can reach 1/7000 of the field of view, corresponding to about 6 μm in this experiment.
基金supported by the National Natural Science Foundation of China(Grant Nos.52188102,52090054 and 52075205)。
文摘Complex surfaces are widely used in aerospace,energy,and national defense industries.As one of the major means of manufacturing such as complex surfaces,the multi-axis numerical control(NC)machining technique makes much contribution.When the size of complex surfaces is large or the machining space is narrow,the multi-axis NC machining may not be a good choice because of its high cost and low dexterity.Robotic machining is a beneficial supplement to the NC machining.Since it has the advantages of large operating space,good dexterity,and easy to realize parallel machining,it is a promising technique to enhance the capability of traditional NC machining.However,whether it is the multi-axis NC machining or the robotic machining,owing to the complex geometric properties and strict machining requirements,high-efficiency and high-accuracy machining of complex surfaces has always been a great challenge and remains a cutting-edge problem in the current manufacturing field.In this paper,by surveying the machining of complex parts and large complex surfaces,the theory and technology of high-efficiency and high-accuracy machining of complex surfaces are reviewed thoroughly.Then,a series of typical applications are introduced to show the state-of-the-art on the machining of complex surfaces,especially the recently developed industrial software and equipment.Finally,the summary and prospect of the machining of complex surfaces are addressed.To the best of our knowledge,this may be the first attempt to systematically review the machining of complex surfaces by the multiaxis NC and robotic machining techniques,in order to promote the further research in related fields.
文摘Because of the developed economy and lush vegetation in southern China, the following obstacles or difficulties exist in remote sensing land surface classification: 1) Diverse surface composition types;2) Undulating terrains;3) Small fragmented land;4) Indistinguishable shadows of surface objects. It is our top priority to clarify how to use the concept of big data (Data mining technology) and various new technologies and methods to make complex surface remote sensing information extraction technology develop in the direction of automation, refinement and intelligence. In order to achieve the above research objectives, the paper takes the Gaofen-2 satellite data produced in China as the data source, and takes the complex surface remote sensing information extraction technology as the research object, and intelligently analyzes the remote sensing information of complex surface on the basis of completing the data collection and preprocessing. The specific extraction methods are as follows: 1) extraction research on fractal texture features of Brownian motion;2) extraction research on color features;3) extraction research on vegetation index;4) research on vectors and corresponding classification. In this paper, fractal texture features, color features, vegetation features and spectral features of remote sensing images are combined to form a combination feature vector, which improves the dimension of features, and the feature vector improves the difference of remote sensing features, and it is more conducive to the classification of remote sensing features, and thus it improves the classification accuracy of remote sensing images. It is suitable for remote sensing information extraction of complex surface in southern China. This method can be extended to complex surface area in the future.
基金supported by the financial support of Natural Science Research Program of Jiangsu Education Department(No.13KJB310014)Natural Science Foundation of Jiangsu Province(BK20140429)the Natural Science Foundation of Nantong University(No.14ZY015,No.13R23)
文摘The aim of this study was to investigate the inhibitory effect of heparin/fibronectin (Hep/Fn) complexes on neointimal hyperplasia following endovascular intervention. Hep/Fn complexes were immobilized onto titanium (Ti) surfaces, with subsequent X-ray photoelectron spectroscopy (XPS), Toluidine Blue 0 (TBO) and immunohistochemistry methods were used to characterize surface properties. Smooth muscle cell (SMC) cultures were used to evaluate the effect of Hep/Fn complexes on SMC proliferation. Results showed that Hep/Fn complexes successfully immobilized onto Ti surfaces and resulted in an inhibition of SMC proliferation. This study suggests that Hep/Fn surface-immobilized biomaterials develop as a new generation of biomaterials to prevent neointimal hyperplasia, particularly for use in cardiovascular implants.
基金supported by the National Natural Science Foundation of China(No.20801012)New Energy Technology Co.Ltd.of Ai Naji of Jiangsu Province(No.8507040091)
文摘The crystal structure of one novel Mn(II) complex, [Mn(pmta)_3]_2[Mn(H_2O)_6]·4H_2O(1), is reported(Hpmta = 5-methyl-1-phenyl-1H-1,2,3-triazole-4-carboxylic acid). In the title compound, the asymmetric unit consists of a [Mn(pmta_)3]ˉ anion, half [Mn(H_2O)_6]^(2+) counter cation and two lattice H_2O molecules, and the intra- and intermolecular hydrogen bonds connect the complex into a supramolecular structure. The liquid-state fluorescence spectra of complex 1 have been determined. Hirshfeld surface analysis was also studied. The main intermolecular interactions in the complex are O···H and H···H contacts.
文摘The complexation of phosphates in the quartz-metal ion-H_2O-oleate system was studied. Computer assisted calculations with the aid of the advanced program SOLGASWATER and known equilibrium constants were used to evaluate the mechanism,The calculation results revealed that in the presence of a certain amount of phosphates, metal ions adsorbed at the quartz-H_2O interface will be transferred into solution.Thus the competi- tion for metal ions between phosphates and the quartz surface leads to surface deactivation and re- duced floatability.Various distribution diagrams clearly demonstrate the change of surface complexation as a function of added phosphate concentration.The deactivation products were also evaluated.
基金The project surported by State"863"PlanNational Natural science fund.
文摘A novel method for preparing metalllzed film has been studied.The reduction process and properties of the poly(vinyl alcohol)(PVA)were probed by several analytic means.According to the etudies,a mechanism for the polymer surface reduction metallization was proposed and proved.
文摘FT IR, Raman microscopy, XRD, 29 Si and 27 Al MAS NMR, were used to investigate changes in surface properties of a natural illite sample after acid base potentiometric titration. The characteristic XRD lines indicated the presence of surface Al Si complexes, preferable to Al(OH) 3 precipitates. In the microscopic Raman spectra, the vibration peaks of Si O and Al O bonds diminished as a result of treatment with acid, then increased after hydroxide back titration. The varied ratio of signal intensity between IV Al and VI Al species in 27 Al MAS NMR spectra, together with the stable BET surface area after acidimetric titration, suggested that edge faces and basal planes in the layer structure of illite participated in dissolution of structural components. The combined spectroscopic evidence demonstrated that the reactions between illite surfaces and acid leaching silicic acid and aluminum ions should be considered in the model description of surface acid base properties of the aqueous illite.
文摘A magnetic abrasive finishing process using an alternating magnetic field is proposed for the finishing of complex surfaces.In an alternating field,the periodic changes in current will cause the magnetic cluster used as a magnetic brush to fluctuate,which will not only continuously replace the abrasive particles in contact with the workpiece,but also periodically adjust the shape of the magnetic cluster to better fit the surface of the workpiece.In this paper,the influence of a combination of alternating and static magnetic fields on the magnetic field in the finishing area is analyzed.The feasibility of this process for finishing micro-grooves is investigated.Simulations and experimental measurements show that the combination of alternating and static magnetic fields can retain the advantages of the alternating field while increasing the magnetic flux density in the finishing area.The experimental results show that the process is feasible for finishing micro-grooves,with an excellent deburring effect on the groove edges.
基金supported by the National Key R&D Program of China under[grant number 2021YFF0704600]the National Natural Science Foundation of China under[grant number 42171352,42271365,U22A20566]the High-Level Talent Aggregation Project in Hunan Province,China-Innovation Team under[grant number 2019RS1060].
文摘Spaceborne photon-counting LiDAR is significantly affected by noise,and existing denoising algorithms cannot be universally adapted to different surface types and topographies under all observation conditions.Accordingly,a new denoising method is presented to extract signal photons adaptively.The method includes two steps.First,the local neighborhood radius is calculated according to photons’density,then thefirst-step denoising process is completed via photons’curvature feature based on KNN search and covariance matrix.Second,the local photonfiltering direction and threshold are obtained based on thefirst-step denoising results by RANSAC and elevation frequency histogram,and the local dense noise photons that thefirst-step cannot be identified are further eliminated.The following results are drawn:(1)experimental results on MATLAS with different topographies indicate that the average accuracy of second-step denoising exceeds 0.94,and the accuracy is effectively improves with the number of denoising times;(2)experiments on ICESat-2 under different observation conditions demonstrate that the algorithm can accurately identify signal photons in different surface types and topographies.Overall,the proposed algorithm has good adaptability and robustness for adaptive denoising of large-scale photons,and the denoising results can provide more reasonable and reliable data for sustainable urban development.
基金National Natural Science Foundation of China (51075013) Beijing Natural Science Foundation (4102035)+1 种基金 Fundamental Research Funds for the Central Universities (YWF-10-01-A09) Research Foundation of State Key Laboratory for Manufacturing Systems Engineering (Xi'an Jiaotong University)
文摘To improve the grinding quality of robotic belt grinding systems for the workpieces with complex shaped surfaces, new concepts of the dexterity grinding point and the dexterity grinding space are proposed and their mathematical descriptions are defined. Factors influencing the dexterity grinding space are analyzed. And a method to determine the necessary dexterity grinding space is suggested. Based on particle swarm optimization (PSO) method, a strategy to optimize the grinding robot structural dimensions and position with respect to the grinding wheel is put forward to obtain the necessary dexterity grinding space. Finally, to grind an aerial engine blade, a dedicated PPPRRR (P: prismatic R: rotary) grinding robot structural dimensions and position with respect to the grinding wheel are optimized using the above strategy. According to simulation results, if the blade is placed within the dexterity grinding space, only one gripper and one grinding machine are needed to grind its complex shaped surfaces.
基金supported by the National Natural Science Foundation of China(Grant Nos.11572094,51579055 and 51509048)
文摘The absorber is known to be vertical axisymmetric for a single-point wave energy converter (WEC). The shape of the wetted surface usually has a great influence on the absorber's hydrodynamic characteristics which are closely linked with the wave power conversion ability. For complex wetted surface, the hydrodynamic coefficients have been predicted traditionally by hydrodynamic software based on the BEM. However, for a systematic study of various parameters and geometries, they are too multifarious to generate so many models and data grids. This paper examines a semi-analytical method of decomposing the complex axisyrnmetric boundary into several ring-shaped and stepped surfaces based on the boundary discretization method (BDM) which overcomes the previous difficulties. In such case, by using the linear wave theory based on eigenfunction expansion matching method, the expressions of velocity potential in each domain, the added mass, radiation damping and wave excitation forces of the oscillating absorbers are obtained. The good astringency of the hydrodynamic coefficients and wave forces are obtained for various geometries when the discrete number reaches a certain value. The captured wave power for a same given draught and displacement for various geometries are calculated and compared. Numerical results show that the geometrical shape has great effect on the wave conversion performance of the absorber. For absorbers with the same outer radius and draught or displacement, the cylindrical type shows fantastic wave energy conversion ability at some given frequencies, while in the random sea wave, the parabolic and conical ones have better stabilization and applicability in wave power conversion.
基金National Natural Science Foundation of China(NSFC,No.11475008)。
文摘During the chemical weathering of the uranium mill tailings,released uranium could be immobilized by the newly formed secondary minerals such as oxyhydroxides.A deeper understanding of the interaction between uranium and common oxyhydroxides under environmental conditions is necessary.In this work,uranium sorption behaviors on Al-,Mn-and Fe-oxyhydroxide minerals(boehmite,manganite,goethite,and lepidocrocite)were investigated by batch experiments.Results showed that the uranium sorption on Al-oxyhydroxide behaved significantly differently from the other three minerals.The sorption edge of the Mn-and Fe-oxyhydroxides located around pH 5,while the sorption edge of boehmite shifted about 1.5 pH unit to near neutral.The sorption isotherms of uranium on manganite,goethite and lepidocrocite at pH 5.0 could be well fitted by the Langmuir model.Instead of surface complexation,sorption on boehmite happened mainly by uranium-bearing carbonates and hydroxides precipitation as illustrated by the characterization results.Both carbonate and phosphate strongly affected the uranium sorption behavior.The removal efficiency of uranium by boehmite exceeded 98%after three sorption-desorption cycles,indicating it may be a potential material for uranium removal and recovery.
基金Acknowledgements The authors would like m thank the anonymous reviewers for providing comments to improve the quality of this paper, and iSPACE of Research Studios Austria FG (RSA) (http://ispace.researchstudio. at/) for providing the ALS datasets. The study described in this paper is funded by the National Natural Science Foundation of China (Grant No. 41301493), the High Resolution Earth Observation Science Foundation of China (GFZX04060103-5-17), and Special Fund for Surveying and Mapping Scientific Research in the Public Interest (201412007).
文摘Airborne laser scanning (ALS) is a technique used to obtain Digital Surface Models (DSM) and Digital Terrain Models (DTM) efficiently, and filtering is the key procedure used to derive DTM from point clouds. Generating seed points is an initial step for most filtering algorithms, whereas existing algorithms usually define a regular window size to generate seed points. This may lead to an inadequate density of seed points, and further introduce error type I, especially in steep terrain and forested areas. In this study, we propose the use of object- based analysis to derive surface complexity information from ALS datasets, which can then be used to improve seed point generation. We assume that an area is complex if it is composed of many small objects, with no buildings within the area. Using these assumptions, we propose and implement a new segmentation algorithm based on a grid index, which we call the Edge and Slope Restricted Region Growing (ESRGG) algorithm. Surface complexity information is obtained by statistical analysis of the number of objects derived by segmentation in each area. Then, for complex areas, a smaller window size is defined to generate seed points. Experimental results show that the proposed algorithm could greatly improve the filtering results in complex areas, especially in steep terrain and forested areas.
基金supported by the National Key R&D Program of China(Grant No.2016YFC0200500)the Youth Project of National Natural Science Foundation of China(Grant No.41805007)。
文摘Based on observation data from urban observation stations in Nanjing and Suzhou at two heights in the roughness sublayer above the canopy and observation data at three heights in the SORPES station at the Xianlin Campus of Nanjing University in a suburban area,the of land-atmosphere turbulent flux exchange and the energy balance over complex underlying surfaces were analyzed.The results indicated that in the roughness sublayer above the canopy,the nearsurface momentum flux,sensible heat flux,and latent heat flux increase with height,and the observation value of the surface albedo increases with height.However,the observation value of the net radiation decreases with height,thus resulting in a change in the urban surface energy budget with height.At the SORPES station in the Xianlin Campus of Nanjing University located in a hilly area,the momentum flux,sensible heat flux,and latent heat flux of the ground observation field significantly differed from those of the two heights on the tower,while the two heights on the tower were extremely close.These results indicate that the flux observation over the complex underlying surface exhibits adequate local only when it is conducted at a higher altitude above the ground.The turbulent flux observation results at a lower altitude in urban areas are underestimated,while the turbulent flux observation results near the surface produce a large deviation over the underlying hilly complex.
基金This work was supported by the National Natural Science Foundation of China.
文摘In this study,the surface properties and adsorption properties of the Le An River sedi- ment were modelled via surface complexation approach.The model parameters were determined based on the data of our potentiometric titration experiments and the metal adsorption experiments with the Le An River sediment samples.Consequently,the surface complexation models for the natural sediment,in our case the Le An River sediments,which can interpret the experimental data very well were successfully established.Three typical surface complexation models that is the con- stant capacitance model,the diffuse layer model and the triple layer model,were considered in this research.This work indicated that the consistency and the interdependency among model parame- ters together with the selection of the surface adsorbed species should be emphasized.
文摘The correlation between surface complexation at the SiO_(2)H_(2)O interface and quartz notation behavior was studied.Computer assisted calculations,using the programs SOLGASWATER,were adapted in order to con-struct distribution diagrams of surface speciation in the SiO_(2)-metal ion-H^(+) system in aqueous solutions.Equilib-rium constants for both surface and solution reactions were introduced in the composition matrix.Surface complexation,surface charge as well as notation results were compared and a good agreement was obtained.Furthermore,flotation mechanisms of quartz activation by common metal ions like Ca^(2+),Mg^(2+),Fe^(2+) are quantitatively discussed based on the surface reaction equilibrium constants.