Based on the Boltzmann’s superposition principles of linear viscoelastic materials and the von K*-rm*-n’s hypotheses of thin plates with large deflections, a mathematical model for quasi-static problems of viscoelas...Based on the Boltzmann’s superposition principles of linear viscoelastic materials and the von K*-rm*-n’s hypotheses of thin plates with large deflections, a mathematical model for quasi-static problems of viscoelastic thin plates was given. By the Galerkin method in spatial domain, the original integro-partial-differential system could be transformed into an integral system. The latter further was reduced to a differential system by using the new method for temporal domain presented in this paper. Numerical results show that compared with the ordinary finite difference method, the new method in this paper is simpler to operate and has some advantages, such as, no storage and quicker computational speed etc.展开更多
Studying and understanding of the surface topography variation are the basis for analyzing tribological problems,and characterization of worn surface is necessary.Fractal geometry offers a more accurate description fo...Studying and understanding of the surface topography variation are the basis for analyzing tribological problems,and characterization of worn surface is necessary.Fractal geometry offers a more accurate description for surface roughness that topographic surfaces are statistically self-similar and can be quantitatively evaluated by fractal parameters.The change regularity of worn surface topography is one of the most important aspects of running-in study.However,the existing research normally adopts only one friction matching pair to explore the surface topography change,which interrupts the running-in wear process and makes the experimental result lack authenticity and objectivity.In this paper,to investigate the change regularity of surface topography during the real running-in process,a series of running-in tests by changing friction pairs under the same operating conditions are conducted on UMT-II Universal Multifunction Tester.The surface profile data are acquired by MiaoXAM2.5X-50X Ultrahigh Precision Surface 3D Profiler and analyzed using fractal dimension D,scale coefficient C and characteristic roughness Ra ＊based on root mean square（RMS） method.The characterization effects of the three parameters are discussed and compared.The results obtained show that there exists remarkable fractal feature of surface topography during running-in process,both D and Ra ＊increase gradually,while C decreases slowly as the wear-in process goes on,and all parameters tend to be stable when the wear process steps into the normal wear process.Ra ＊illustrates higher sensitivity for rough surface characterization compared with the other two parameters.In addition,the running-in test carried with a set of identical surface properties is more scientific and reasonable than the traditional one.The proposed research further indicates that the fractal method can quantitatively measure the rough surface,which also provides an evidence for running-in process identification and tribology design.展开更多
The Modified Recursive Fourier Meth(MRFM) is presented here and applied to DISA series integrated substation automation systems for AC measurement comparing with the other measure methods used in RTUs. The application...The Modified Recursive Fourier Meth(MRFM) is presented here and applied to DISA series integrated substation automation systems for AC measurement comparing with the other measure methods used in RTUs. The application shows its high accuracy, good real time response. And it can measure harmonic in real bine.展开更多
Approximate analytical bound-state solutions of the Dirac particle in the fields of attractive and repulsive Rosen–Morse （RM） potentials including the Coulomb-like tensor （CLT） potential are obtained for arbitrar...Approximate analytical bound-state solutions of the Dirac particle in the fields of attractive and repulsive Rosen–Morse （RM） potentials including the Coulomb-like tensor （CLT） potential are obtained for arbitrary spin–orbit quantum number κ. The Pekeris approximation is used to deal with the spin–orbit coupling terms κ（κ ± 1）r 2 . In the presence of exact spin and pseudospin （p-spin） symmetries, the energy eigenvalues and the corresponding normalized two-component wave functions are found by using the parametric generalization of the Nikiforov–Uvarov （NU） method. The numerical results show that the CLT interaction removes degeneracies between the spin and p-spin state doublets.展开更多
文摘Based on the Boltzmann’s superposition principles of linear viscoelastic materials and the von K*-rm*-n’s hypotheses of thin plates with large deflections, a mathematical model for quasi-static problems of viscoelastic thin plates was given. By the Galerkin method in spatial domain, the original integro-partial-differential system could be transformed into an integral system. The latter further was reduced to a differential system by using the new method for temporal domain presented in this paper. Numerical results show that compared with the ordinary finite difference method, the new method in this paper is simpler to operate and has some advantages, such as, no storage and quicker computational speed etc.
基金supported by National Natural Science Foundation of China (Grant No.50975276,Grant No.50475164)National Basic Research Program of China (973 Program,Grant No.2007CB607605)Doctoral Programs Foundation of Ministry of Education of China (Grant No.200802900513)
文摘Studying and understanding of the surface topography variation are the basis for analyzing tribological problems,and characterization of worn surface is necessary.Fractal geometry offers a more accurate description for surface roughness that topographic surfaces are statistically self-similar and can be quantitatively evaluated by fractal parameters.The change regularity of worn surface topography is one of the most important aspects of running-in study.However,the existing research normally adopts only one friction matching pair to explore the surface topography change,which interrupts the running-in wear process and makes the experimental result lack authenticity and objectivity.In this paper,to investigate the change regularity of surface topography during the real running-in process,a series of running-in tests by changing friction pairs under the same operating conditions are conducted on UMT-II Universal Multifunction Tester.The surface profile data are acquired by MiaoXAM2.5X-50X Ultrahigh Precision Surface 3D Profiler and analyzed using fractal dimension D,scale coefficient C and characteristic roughness Ra ＊based on root mean square（RMS） method.The characterization effects of the three parameters are discussed and compared.The results obtained show that there exists remarkable fractal feature of surface topography during running-in process,both D and Ra ＊increase gradually,while C decreases slowly as the wear-in process goes on,and all parameters tend to be stable when the wear process steps into the normal wear process.Ra ＊illustrates higher sensitivity for rough surface characterization compared with the other two parameters.In addition,the running-in test carried with a set of identical surface properties is more scientific and reasonable than the traditional one.The proposed research further indicates that the fractal method can quantitatively measure the rough surface,which also provides an evidence for running-in process identification and tribology design.
文摘The Modified Recursive Fourier Meth(MRFM) is presented here and applied to DISA series integrated substation automation systems for AC measurement comparing with the other measure methods used in RTUs. The application shows its high accuracy, good real time response. And it can measure harmonic in real bine.
基金Project partially supported by the Scientific and Technological Research Council of Turkey (Grant No. TBíTAK)
文摘Approximate analytical bound-state solutions of the Dirac particle in the fields of attractive and repulsive Rosen–Morse （RM） potentials including the Coulomb-like tensor （CLT） potential are obtained for arbitrary spin–orbit quantum number κ. The Pekeris approximation is used to deal with the spin–orbit coupling terms κ（κ ± 1）r 2 . In the presence of exact spin and pseudospin （p-spin） symmetries, the energy eigenvalues and the corresponding normalized two-component wave functions are found by using the parametric generalization of the Nikiforov–Uvarov （NU） method. The numerical results show that the CLT interaction removes degeneracies between the spin and p-spin state doublets.
