Parts with high-quality freeform surfaces have been widely used in industries,which require strict quality control during the manufacturing process.Among all the industrial inspection methods,contact measurement with ...Parts with high-quality freeform surfaces have been widely used in industries,which require strict quality control during the manufacturing process.Among all the industrial inspection methods,contact measurement with coordinate measuring machines or computer numerical control machine tool is a fundamental technique due to its high accuracy,robustness,and universality.In this paper,the existing research in the contact measurement field is systematically reviewed.First,different configurations of the measuring machines are introduced in detail,which may have influence on the corresponding sampling and inspection path generation criteria.Then,the entire inspection pipeline is divided into two stages,namely the pre-inspection and post-inspection stages.The typical methods of each sub-stage are systematically overviewed and classified,including sampling,accessibility analysis,inspection path generation,probe tip radius compensation,surface reconstruction,and uncertainty analysis.Apart from those classical research,the applications of the emerging deep learning technique in some specific tasks of measurement are introduced.Furthermore,some potential and promising trends are provided for future investigation.展开更多
A new approach based on stereo vision technology is introduced to analyzesheet metal deformation. By measuring the deformed circle grids that are printed on the sheetsurface before forming, the strain distribution of ...A new approach based on stereo vision technology is introduced to analyzesheet metal deformation. By measuring the deformed circle grids that are printed on the sheetsurface before forming, the strain distribution of the workpiece is obtained. The measurement andanalysis results can be used to verify numerical simulation results and guide production. To getgood accuracy, some new techniques are employed: camera calibration based on genetic algorithm,feature abstraction based on self-adaptive technology, image matching based on structure feature andcamera modeling pre-constrains, and parameter calculation based on curve and surface optimization.The experimental values show that the approach proposed is rational and practical, which can providebetter measurement accuracy with less time than the conventional method.展开更多
X-ray photoelectron spectroscopy (XPS) and automatic titrimeter were nsed to study the relation be-tween pH and the transformation of the coordinate forms of P on goethite surfaces. The results showed thatfor a given ...X-ray photoelectron spectroscopy (XPS) and automatic titrimeter were nsed to study the relation be-tween pH and the transformation of the coordinate forms of P on goethite surfaces. The results showed thatfor a given P concentration, increasing the pH of suspension could cause a fast transformation of monodentatecomplexes of phosphate ions on goethite surfaces to binuclear ones. When lowering the PH, additional adsorp-tion of P occurred and the binuclear complexes reverted slowly to the monodentate ones. The dissociationand association of protons of the sorbed P caused by PH changes was considered to be a major reason lewtingto the transformation of the coordinate forms of P on the surfaces. The stability of binuclear surface complexof P was greater than that of monodentate complex. The possible reactions on the interface of goethite andsolutions with pH changes, and the reasons causing the different stabilities of the two coordinate P complexesare discussed in the paper.展开更多
A planar nonlinear weak form quadrature beam element of arbitrary number of axial nodes is proposed on the basis of the absolute nodal coordinate formulation (ANCF). Elastic forces of the element are established throu...A planar nonlinear weak form quadrature beam element of arbitrary number of axial nodes is proposed on the basis of the absolute nodal coordinate formulation (ANCF). Elastic forces of the element are established through geometrically exact beam theory, resulting in good consistency with classical beam theory. Two examples with strong geometrical nonlinearity are presented to verify the effec-tiveness of the formulation.展开更多
The effects of forming damage are analyzed,which occur during hot stamping process,on the load-carrying capacity and failure mode of hot stamped beams.A damage-coupled pre-forming constitutive model was proposed,in wh...The effects of forming damage are analyzed,which occur during hot stamping process,on the load-carrying capacity and failure mode of hot stamped beams.A damage-coupled pre-forming constitutive model was proposed,in which the damage during hot stamping process was introduced into the service response.The constitutive model was applied into the three-point bending simulation of a hot stamped beam,and then the influences of forming damage on the load-carrying capacity and cracks propagation were investigated.The results show that the forming damage reduces the maximum load capacity of the hot stamped beam by 7.5%.It also causes the crack to occur earlier and promotes crack to propagate along the radial direction of the punch.展开更多
Lu:If the tense situations in the Middle East and Northeast Asiabecome relaxed,it would certainly exert great influence on world politi-cal pattern.Can non-traditional security solve the contradictions in thetradition...Lu:If the tense situations in the Middle East and Northeast Asiabecome relaxed,it would certainly exert great influence on world politi-cal pattern.Can non-traditional security solve the contradictions in thetraditional security field?Will the major powers continue to cooperate inthe anti-terrorist campaign?All these issues will face challenges展开更多
A non contact three dimensional measurement method is presented in this paper.This system consists of a laser triangulation probe,a probe head and a coordinate measuring machine (CMM).The measurement principle of th...A non contact three dimensional measurement method is presented in this paper.This system consists of a laser triangulation probe,a probe head and a coordinate measuring machine (CMM).The measurement principle of the system is discussed,and a system calibration method employing a reference ball is proposed.The geometric model involving four frames is established to calculate the data points based on the reading of the laser probe and position information from the CMM.A measuring experiment for gesso free form surface using this system is carried out.展开更多
Various transforms of the indeterminate forms are presented in this part, which include simplification in spherical coordinates, origin translation, axis alteration, transformation of limit conservation and applicatio...Various transforms of the indeterminate forms are presented in this part, which include simplification in spherical coordinates, origin translation, axis alteration, transformation of limit conservation and application of Xh?K0. Fundamental factors for numerical simplification are provided respectively for bi-variable indeterminate forms, tri-variable indeterminate forms and the universal extending multiplier.展开更多
以静止无功发生器(static var generator,SVG)为例,针对构网型逆变器和SVG并联系统的电压稳定性问题,提出构网型逆变器与SVG并联系统无功功率协调控制策略。将并联系统的运行状态总结为四种工况,通过工况识别、无功补偿量计算、无功功...以静止无功发生器(static var generator,SVG)为例,针对构网型逆变器和SVG并联系统的电压稳定性问题,提出构网型逆变器与SVG并联系统无功功率协调控制策略。将并联系统的运行状态总结为四种工况,通过工况识别、无功补偿量计算、无功功率分配策略、工况切换,来协调不同工况下构网型逆变器与SVG注入公共耦合点的无功功率,使并联系统在各种情况下均可稳定可靠工作。在MATLAB中搭建模型并进行仿真,结果表明所提控制策略可以实现工况的快速识别与切换、无功补偿量的计算、无功功率的分配,以及对公共耦合点电压的快速支撑。展开更多
The constant stress patch test condition has widely been studied in terms of Cartesian coordinates. However, such kind of conditions cannot be used for curvilinear coordinates. In this paper, certain forms of the patc...The constant stress patch test condition has widely been studied in terms of Cartesian coordinates. However, such kind of conditions cannot be used for curvilinear coordinates. In this paper, certain forms of the patch test are established in terms of the general and the orthogonal curvilinear systems respectively. For the axisymmetric problem, the related patch test condition is formulated and used to construct an axisymmetric incompatible element. In addition, some new approaches to avoid spurious shear stress are presented.展开更多
A new form of geodetic coordinate system based on geodesic coordinates instead of geodetic longitude and latitude was proposed.The vertical and horizontal geodesic coordinates measured with length were defined as coor...A new form of geodetic coordinate system based on geodesic coordinates instead of geodetic longitude and latitude was proposed.The vertical and horizontal geodesic coordinates measured with length were defined as coordinate parameters,but the two families of coordinate curves were still meridians and parallel circles.The first fundamental form on the ellipsoidal surface and its three coefficients were deduced by the geodesic coordinate.The formula for the latitudinal scale factor of length for geodetic parallel lines was derived,by which the obtained result conformed to that standard value calculated from geodetic latitude,and it is applicable in the range of 400 km from north to south.Therefore,it lays the foundation for establishing the differential equation and differential relationship based on this type of coordinate parameters;and consequently,it is convenient and accurate enough to operate on the ellipsoidal surface in this new form of geodetic coordinate system.展开更多
基金partially supported by the Natural Science Foundation of Shanghai(Grant No.22ZR1435200)the National Natural Science Foundation of China(Grant No.52075337)the Open Research Fund of State Key Laboratory of Digital Manufacturing and Equipment Technology,HUST(Grant No.DMETKF2022010)。
文摘Parts with high-quality freeform surfaces have been widely used in industries,which require strict quality control during the manufacturing process.Among all the industrial inspection methods,contact measurement with coordinate measuring machines or computer numerical control machine tool is a fundamental technique due to its high accuracy,robustness,and universality.In this paper,the existing research in the contact measurement field is systematically reviewed.First,different configurations of the measuring machines are introduced in detail,which may have influence on the corresponding sampling and inspection path generation criteria.Then,the entire inspection pipeline is divided into two stages,namely the pre-inspection and post-inspection stages.The typical methods of each sub-stage are systematically overviewed and classified,including sampling,accessibility analysis,inspection path generation,probe tip radius compensation,surface reconstruction,and uncertainty analysis.Apart from those classical research,the applications of the emerging deep learning technique in some specific tasks of measurement are introduced.Furthermore,some potential and promising trends are provided for future investigation.
文摘A new approach based on stereo vision technology is introduced to analyzesheet metal deformation. By measuring the deformed circle grids that are printed on the sheetsurface before forming, the strain distribution of the workpiece is obtained. The measurement andanalysis results can be used to verify numerical simulation results and guide production. To getgood accuracy, some new techniques are employed: camera calibration based on genetic algorithm,feature abstraction based on self-adaptive technology, image matching based on structure feature andcamera modeling pre-constrains, and parameter calculation based on curve and surface optimization.The experimental values show that the approach proposed is rational and practical, which can providebetter measurement accuracy with less time than the conventional method.
文摘X-ray photoelectron spectroscopy (XPS) and automatic titrimeter were nsed to study the relation be-tween pH and the transformation of the coordinate forms of P on goethite surfaces. The results showed thatfor a given P concentration, increasing the pH of suspension could cause a fast transformation of monodentatecomplexes of phosphate ions on goethite surfaces to binuclear ones. When lowering the PH, additional adsorp-tion of P occurred and the binuclear complexes reverted slowly to the monodentate ones. The dissociationand association of protons of the sorbed P caused by PH changes was considered to be a major reason lewtingto the transformation of the coordinate forms of P on the surfaces. The stability of binuclear surface complexof P was greater than that of monodentate complex. The possible reactions on the interface of goethite andsolutions with pH changes, and the reasons causing the different stabilities of the two coordinate P complexesare discussed in the paper.
文摘A planar nonlinear weak form quadrature beam element of arbitrary number of axial nodes is proposed on the basis of the absolute nodal coordinate formulation (ANCF). Elastic forces of the element are established through geometrically exact beam theory, resulting in good consistency with classical beam theory. Two examples with strong geometrical nonlinearity are presented to verify the effec-tiveness of the formulation.
基金Supported by the National Natural Science Foundation of China(5137520151775227)。
文摘The effects of forming damage are analyzed,which occur during hot stamping process,on the load-carrying capacity and failure mode of hot stamped beams.A damage-coupled pre-forming constitutive model was proposed,in which the damage during hot stamping process was introduced into the service response.The constitutive model was applied into the three-point bending simulation of a hot stamped beam,and then the influences of forming damage on the load-carrying capacity and cracks propagation were investigated.The results show that the forming damage reduces the maximum load capacity of the hot stamped beam by 7.5%.It also causes the crack to occur earlier and promotes crack to propagate along the radial direction of the punch.
文摘Lu:If the tense situations in the Middle East and Northeast Asiabecome relaxed,it would certainly exert great influence on world politi-cal pattern.Can non-traditional security solve the contradictions in thetraditional security field?Will the major powers continue to cooperate inthe anti-terrorist campaign?All these issues will face challenges
基金Supported by"863"High Technology Development Comittee ofChina (No."863"- 51 1 - 942 - 0 2 4 ) National Natural Science Foun-dation of China (No.50 0 750 64)
文摘A non contact three dimensional measurement method is presented in this paper.This system consists of a laser triangulation probe,a probe head and a coordinate measuring machine (CMM).The measurement principle of the system is discussed,and a system calibration method employing a reference ball is proposed.The geometric model involving four frames is established to calculate the data points based on the reading of the laser probe and position information from the CMM.A measuring experiment for gesso free form surface using this system is carried out.
文摘Various transforms of the indeterminate forms are presented in this part, which include simplification in spherical coordinates, origin translation, axis alteration, transformation of limit conservation and application of Xh?K0. Fundamental factors for numerical simplification are provided respectively for bi-variable indeterminate forms, tri-variable indeterminate forms and the universal extending multiplier.
文摘以静止无功发生器(static var generator,SVG)为例,针对构网型逆变器和SVG并联系统的电压稳定性问题,提出构网型逆变器与SVG并联系统无功功率协调控制策略。将并联系统的运行状态总结为四种工况,通过工况识别、无功补偿量计算、无功功率分配策略、工况切换,来协调不同工况下构网型逆变器与SVG注入公共耦合点的无功功率,使并联系统在各种情况下均可稳定可靠工作。在MATLAB中搭建模型并进行仿真,结果表明所提控制策略可以实现工况的快速识别与切换、无功补偿量的计算、无功功率的分配,以及对公共耦合点电压的快速支撑。
文摘The constant stress patch test condition has widely been studied in terms of Cartesian coordinates. However, such kind of conditions cannot be used for curvilinear coordinates. In this paper, certain forms of the patch test are established in terms of the general and the orthogonal curvilinear systems respectively. For the axisymmetric problem, the related patch test condition is formulated and used to construct an axisymmetric incompatible element. In addition, some new approaches to avoid spurious shear stress are presented.
基金supported by the National Natural Science Foundation of China(Grant No.40471114).
文摘A new form of geodetic coordinate system based on geodesic coordinates instead of geodetic longitude and latitude was proposed.The vertical and horizontal geodesic coordinates measured with length were defined as coordinate parameters,but the two families of coordinate curves were still meridians and parallel circles.The first fundamental form on the ellipsoidal surface and its three coefficients were deduced by the geodesic coordinate.The formula for the latitudinal scale factor of length for geodetic parallel lines was derived,by which the obtained result conformed to that standard value calculated from geodetic latitude,and it is applicable in the range of 400 km from north to south.Therefore,it lays the foundation for establishing the differential equation and differential relationship based on this type of coordinate parameters;and consequently,it is convenient and accurate enough to operate on the ellipsoidal surface in this new form of geodetic coordinate system.
