A new degradation function of the friction coefficient is used.Based on the double shear-lag model and Paris formula,the interracial damage of coated- fiber-reinforced composites under tension-tension cyclic loading i...A new degradation function of the friction coefficient is used.Based on the double shear-lag model and Paris formula,the interracial damage of coated- fiber-reinforced composites under tension-tension cyclic loading is studied.The effects of strength and thickness of the coating materials on the debond stress,debond rate as well as debond length are simulated.展开更多
A linear response history analysis method is used to determine the influence of three factors:geometric incoherency,wave-passage,and local site characteristics on the response of lnulti-support structures subjected to...A linear response history analysis method is used to determine the influence of three factors:geometric incoherency,wave-passage,and local site characteristics on the response of lnulti-support structures subjected to differential ground motions.A one-span frame and a reduced model of a 24-span bridge,located in Las Vegas,Nevada are studied,in which the influence of each of the three factors and their combinations are analyzed.It is revealed that the incoherency of earthquake ground motion can have a dramatic influence on structural response by modifying the dynamics response to uniform excitation and inducing pseudo-static response,which does not exist in structures subjected to uniform excitation.The total response when all three sources of ground motion incoherency are included is generally larger than that of uniform excitation.展开更多
With the help of Complex Function Mapping studied results, the analysis function of Conformal Mapping is set up. Since the complicated three dimension’s deformation problems are transferred into two dimension problem...With the help of Complex Function Mapping studied results, the analysis function of Conformal Mapping is set up. Since the complicated three dimension’s deformation problems are transferred into two dimension problems, both the stream function and strain ratio field are analyzed in the metal plastic deformation. Using the upper-bound principles, the theory of metal deformation and die cavity optimized modeling is established for random special-shaped product extrusion. As a result, this enables the realization of intelligent technique target in the die cavity of CAD/CAM integration.展开更多
The slurry of Al-20Sn alloy was prepared using electromagnetic-mechanical stirring method. The bonding of steel/mushy Al-20Sn was conducted using casting rolling technique. The bonding parameters were 505 ℃ for prehe...The slurry of Al-20Sn alloy was prepared using electromagnetic-mechanical stirring method. The bonding of steel/mushy Al-20Sn was conducted using casting rolling technique. The bonding parameters were 505 ℃ for preheat temperature of steel plate and 10 mm/s for rolling speed. The interfacial mechanical property and structure of steel/mushy Al-20Sn bonding plate were studied. The results show that the relationship between solid fraction of Al-20Sn slurry and interfacial shear strength of bonding plate is S=52.9+0.998φ s-0.014 4φ 2 s (where S is interfacial shear strength, φ s is solid fraction). The largest interfacial shear strength is 70.2 MPa when solid fraction is 34.6%. The interface of bonding plate is made up of Fe-Al compound and Fe-Al solid solution alternatively.展开更多
Rare earth ternary complexes Tb1-xEux（TTA）3Phen（x=0,0.25,0.5,0.75,1.0）were synthesized and characterized by DTA-TG,XRD and infrared（IR）.The photophysical properties of these complexes were studied in detail usin...Rare earth ternary complexes Tb1-xEux（TTA）3Phen（x=0,0.25,0.5,0.75,1.0）were synthesized and characterized by DTA-TG,XRD and infrared（IR）.The photophysical properties of these complexes were studied in detail using ultraviolet absorption spectra and fluorescent spectra.Ultraviolet absorption showed that the energy absorption of the complexes mostly came from ligands.Infrared spectra of Tb1-xEux（TTA）3Phen complexes were similar to the pure complexes.TG curves proved that the complexes were stable.Tb3＋ emission was almost quenched and the Eu3＋ emission was enhanced by codoping the complexes.The Tb3＋ ion acted as an energy transfer bridge that helped energy transfer from poly（N-vinylcar-bazole（PVK）to Eu3＋.In addition,their PL and EL properties were systematically studied.展开更多
The SrAl 2O 4∶Eu 2+ , Nd 3+ and SrAl 2O 4∶Eu 2+ , Dy 3+ long afterglow phosphor were synthesized. Their excitation and emission spectra at different excitation and afterglow characteristics wer...The SrAl 2O 4∶Eu 2+ , Nd 3+ and SrAl 2O 4∶Eu 2+ , Dy 3+ long afterglow phosphor were synthesized. Their excitation and emission spectra at different excitation and afterglow characteristics were analyzed after the excitation power was taken off. The effects of Eu 2+ , Dy 3+ , Nd 3+ mole concentrations on phosphorescence characteristics were also discussed. It is crucial to have trapping levels located at a suitable depth related to the thermal release rate at room temperature. The incorporation of Nd 3+ ions as an auxiliary activator into the SrAl 2O 4∶Eu 2+ system causes very intense and long phosphorescence. The response time of SrAl 2O 4∶Eu 2+ , Dy 3+ phosphors is quicker than that of SrAl 2O 4∶Eu 2+ , Nd 3+ . Phosphorescence characteristics of SrAl 2O 4∶Eu 2+, Nd 3+ is much better than those of SrAl 2O 4∶Eu 2+ , Dy 3+ . The integrate area of the excitation spectrum of SrAl 2O 4∶Eu 2+ , Nd 3+ phosphor is larger than that of SrAl 2O 4∶Eu 2+ , Dy 3+ phosphor within the range of 250～360 nm. For phosphorescence characteristics to the system of SrAl 2O 4∶Eu 2+ , Nd 3+ phosphor, the optimum concentration of Nd 3+ trivalent rare earth ions is 0.05 mol.展开更多
Using the inverse method, the analytical solution of a simply supported piezoelectric beam subjected to a uniformly distributed loading has been studied.First,the polynomials of stress function and induction function ...Using the inverse method, the analytical solution of a simply supported piezoelectric beam subjected to a uniformly distributed loading has been studied.First,the polynomials of stress function and induction function are given.Then, considering the gradient properties of the elastic parameter and the potential funciton as well as the piezoelectric parameter,the analytical solution of a simply supported beam subjected to a uniformly distributed loading is obtained and discussed.展开更多
Hybrid Electric Vehicle (HEV) becomes a popular research project all over the world because of its high efficiency and low emissions. HEV is driven by Internal Combustion (IC) engine and electric motor, and its powert...Hybrid Electric Vehicle (HEV) becomes a popular research project all over the world because of its high efficiency and low emissions. HEV is driven by Internal Combustion (IC) engine and electric motor, and its powertrain is more complex than conventional vehicle. Therefore, the complexity of a HEV powertrain demands a reliable control strategy be developed to guarantee stable and consistent operation. In this paper, EACS is proposed which takes IC engine as a main power unit and the electric motor as an assistant one. Because the fuel consumption of HEV mainly depends on IC engine, EACS restricts the IC engine to operate under the condition with favorable fuel economy. In the paper several control parameters are described such as the maximum torque, the lowest and highest desired battery state of charge (SOC), whose values will affect the performance of HEV remarkably. In addition, the test models of power units for HEV, mathematical models of transmission and vehicle dynamics for HEV are established. A forward-facing simulation software (i.e. driver-to-wheel) based on MATLAB/Simulink is developed to test the performance of EACS and determine the proper value of the control parameters. The simulation results and conclusion are also shown in the paper.展开更多
The use of α-power chirped fiber Bragg gratings for dispersion Cancellation in an optical fiber link is discussed.Numerical and theoretical investigation of recompressing the dispersion-broadened pulse by usingα-pow...The use of α-power chirped fiber Bragg gratings for dispersion Cancellation in an optical fiber link is discussed.Numerical and theoretical investigation of recompressing the dispersion-broadened pulse by usingα-power chirped gratings is made,which shows that,the dispersion-broadened Gaussian pulse after l00km standard fiber(with zero dispersion atλ=1.3μm)trnasmission atλ=1.55μm with initial width of T_(FWHM)=33ps(full width at half maximum)can be perfectly recompressed with the peak reflectivity of 82%by using a 30mm longα-power chirped fiber grating with properαvalue and optimal grating parameters.展开更多
In this paper, a new globally convergent algorithm for nonlinear optimization problems with equality and inequality constraints is presented. The new algorithm is of SQP type which determines a search direction by sol...In this paper, a new globally convergent algorithm for nonlinear optimization problems with equality and inequality constraints is presented. The new algorithm is of SQP type which determines a search direction by solving a quadratic programming subproblem per iteration. Some revisions on the quadratic programming subproblem have been made in such a way that the associated constraint region is nonempty for each point x generated by the algorithm, i.e. , the subproblems always have optimal solutions. The new algorithm has two important properties. The computation of revision parameter for guaranteeing the consistency of quadratic subproblem and the computation of the second order correction step for superlinear convergence use the same inverse of a matrix per iteration, so the computation amount of the new algorithm will not be increased much more than other SQP type algorithms; Another is that the new algorithm can give automatically a feasible point as a starting point for the quadratic subproblems per iteration, this will obivously simplify the computation procedure of the subproblems. Some numerical results are reported.展开更多
An apparent wave velocity varying with the frequency of seismic wave was adopted rather than an arbitrary one. The phase difference spectrum was introduced to consider the non-stationary properties of frequency conten...An apparent wave velocity varying with the frequency of seismic wave was adopted rather than an arbitrary one. The phase difference spectrum was introduced to consider the non-stationary properties of frequency contents in simulating artificial random field. The non-stationary random field on hard site considering the temporal-spatial variation was simulated by the way of spectral representation method. This random field can be used as the input of earthquake ground motion of the seismic response analysis of large-span spatial structures considering the effect of multi-supported excitation.展开更多
The synthesis, characterization and electroluminescence performance of a new type of conjugatedpolymer, poly(2,5-diphenyl-1,3,4-thiadiazolyl)-4,4'-vinylene (TPPV) are presented. A light-emitting diodeconsisted of ...The synthesis, characterization and electroluminescence performance of a new type of conjugatedpolymer, poly(2,5-diphenyl-1,3,4-thiadiazolyl)-4,4'-vinylene (TPPV) are presented. A light-emitting diodeconsisted of ITO/TPPV/Al is driven at about 4.0 V and has a peak emission wavelength of 485 nm. Thisblue-shift of the peak is due to the decrease of conjugate degree of TPPV compared to PPV. This result is inaccord with that determined by XPS and theoretical model of MNDO/3展开更多
A new nonlinear prediction technique is proposed by feedforward neural network, the learning algorithmfor network is a chaotic one. A timc-delay embedding is used to reconstruct the underlying attractor, the predictio...A new nonlinear prediction technique is proposed by feedforward neural network, the learning algorithmfor network is a chaotic one. A timc-delay embedding is used to reconstruct the underlying attractor, the predictionmodel is based on the time evolution of the topological neighboring in the phase space, the spatial neighbors are chosenby the rate of exponential divergence of close trajectory. The model is tested for the Mackey-Glass delay equation andLorentz equations, good results are obtained for the prediction.展开更多
基金The subject supported by the National Natural Science Foundation of China(No.59778034)Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institutions of MOEChina and The Hong Kong Polytechnic University(G-S737)
文摘A new degradation function of the friction coefficient is used.Based on the double shear-lag model and Paris formula,the interracial damage of coated- fiber-reinforced composites under tension-tension cyclic loading is studied.The effects of strength and thickness of the coating materials on the debond stress,debond rate as well as debond length are simulated.
基金the China Scholarship Council and the Teaching and Research Award Program for Outstanding Young Teachers (TRAPOYT) in Higher Education Institutions of MOE,PRC.
文摘A linear response history analysis method is used to determine the influence of three factors:geometric incoherency,wave-passage,and local site characteristics on the response of lnulti-support structures subjected to differential ground motions.A one-span frame and a reduced model of a 24-span bridge,located in Las Vegas,Nevada are studied,in which the influence of each of the three factors and their combinations are analyzed.It is revealed that the incoherency of earthquake ground motion can have a dramatic influence on structural response by modifying the dynamics response to uniform excitation and inducing pseudo-static response,which does not exist in structures subjected to uniform excitation.The total response when all three sources of ground motion incoherency are included is generally larger than that of uniform excitation.
文摘With the help of Complex Function Mapping studied results, the analysis function of Conformal Mapping is set up. Since the complicated three dimension’s deformation problems are transferred into two dimension problems, both the stream function and strain ratio field are analyzed in the metal plastic deformation. Using the upper-bound principles, the theory of metal deformation and die cavity optimized modeling is established for random special-shaped product extrusion. As a result, this enables the realization of intelligent technique target in the die cavity of CAD/CAM integration.
文摘The slurry of Al-20Sn alloy was prepared using electromagnetic-mechanical stirring method. The bonding of steel/mushy Al-20Sn was conducted using casting rolling technique. The bonding parameters were 505 ℃ for preheat temperature of steel plate and 10 mm/s for rolling speed. The interfacial mechanical property and structure of steel/mushy Al-20Sn bonding plate were studied. The results show that the relationship between solid fraction of Al-20Sn slurry and interfacial shear strength of bonding plate is S=52.9+0.998φ s-0.014 4φ 2 s (where S is interfacial shear strength, φ s is solid fraction). The largest interfacial shear strength is 70.2 MPa when solid fraction is 34.6%. The interface of bonding plate is made up of Fe-Al compound and Fe-Al solid solution alternatively.
基金Project supported by the Research Fund for the Doctoral Program of Higher Education(20050010014)the National Development Project of High Technology(Project863)(2006AA03Z412)
文摘Rare earth ternary complexes Tb1-xEux（TTA）3Phen（x=0,0.25,0.5,0.75,1.0）were synthesized and characterized by DTA-TG,XRD and infrared（IR）.The photophysical properties of these complexes were studied in detail using ultraviolet absorption spectra and fluorescent spectra.Ultraviolet absorption showed that the energy absorption of the complexes mostly came from ligands.Infrared spectra of Tb1-xEux（TTA）3Phen complexes were similar to the pure complexes.TG curves proved that the complexes were stable.Tb3＋ emission was almost quenched and the Eu3＋ emission was enhanced by codoping the complexes.The Tb3＋ ion acted as an energy transfer bridge that helped energy transfer from poly（N-vinylcar-bazole（PVK）to Eu3＋.In addition,their PL and EL properties were systematically studied.
文摘The SrAl 2O 4∶Eu 2+ , Nd 3+ and SrAl 2O 4∶Eu 2+ , Dy 3+ long afterglow phosphor were synthesized. Their excitation and emission spectra at different excitation and afterglow characteristics were analyzed after the excitation power was taken off. The effects of Eu 2+ , Dy 3+ , Nd 3+ mole concentrations on phosphorescence characteristics were also discussed. It is crucial to have trapping levels located at a suitable depth related to the thermal release rate at room temperature. The incorporation of Nd 3+ ions as an auxiliary activator into the SrAl 2O 4∶Eu 2+ system causes very intense and long phosphorescence. The response time of SrAl 2O 4∶Eu 2+ , Dy 3+ phosphors is quicker than that of SrAl 2O 4∶Eu 2+ , Nd 3+ . Phosphorescence characteristics of SrAl 2O 4∶Eu 2+, Nd 3+ is much better than those of SrAl 2O 4∶Eu 2+ , Dy 3+ . The integrate area of the excitation spectrum of SrAl 2O 4∶Eu 2+ , Nd 3+ phosphor is larger than that of SrAl 2O 4∶Eu 2+ , Dy 3+ phosphor within the range of 250～360 nm. For phosphorescence characteristics to the system of SrAl 2O 4∶Eu 2+ , Nd 3+ phosphor, the optimum concentration of Nd 3+ trivalent rare earth ions is 0.05 mol.
文摘Using the inverse method, the analytical solution of a simply supported piezoelectric beam subjected to a uniformly distributed loading has been studied.First,the polynomials of stress function and induction function are given.Then, considering the gradient properties of the elastic parameter and the potential funciton as well as the piezoelectric parameter,the analytical solution of a simply supported beam subjected to a uniformly distributed loading is obtained and discussed.
文摘Hybrid Electric Vehicle (HEV) becomes a popular research project all over the world because of its high efficiency and low emissions. HEV is driven by Internal Combustion (IC) engine and electric motor, and its powertrain is more complex than conventional vehicle. Therefore, the complexity of a HEV powertrain demands a reliable control strategy be developed to guarantee stable and consistent operation. In this paper, EACS is proposed which takes IC engine as a main power unit and the electric motor as an assistant one. Because the fuel consumption of HEV mainly depends on IC engine, EACS restricts the IC engine to operate under the condition with favorable fuel economy. In the paper several control parameters are described such as the maximum torque, the lowest and highest desired battery state of charge (SOC), whose values will affect the performance of HEV remarkably. In addition, the test models of power units for HEV, mathematical models of transmission and vehicle dynamics for HEV are established. A forward-facing simulation software (i.e. driver-to-wheel) based on MATLAB/Simulink is developed to test the performance of EACS and determine the proper value of the control parameters. The simulation results and conclusion are also shown in the paper.
基金Supported by the National Natural Science Foundation of China.
文摘The use of α-power chirped fiber Bragg gratings for dispersion Cancellation in an optical fiber link is discussed.Numerical and theoretical investigation of recompressing the dispersion-broadened pulse by usingα-power chirped gratings is made,which shows that,the dispersion-broadened Gaussian pulse after l00km standard fiber(with zero dispersion atλ=1.3μm)trnasmission atλ=1.55μm with initial width of T_(FWHM)=33ps(full width at half maximum)can be perfectly recompressed with the peak reflectivity of 82%by using a 30mm longα-power chirped fiber grating with properαvalue and optimal grating parameters.
基金This research was supported by the National Natural Science Foundation of China and the Natural Science Foundation of Shandong Province.
文摘In this paper, a new globally convergent algorithm for nonlinear optimization problems with equality and inequality constraints is presented. The new algorithm is of SQP type which determines a search direction by solving a quadratic programming subproblem per iteration. Some revisions on the quadratic programming subproblem have been made in such a way that the associated constraint region is nonempty for each point x generated by the algorithm, i.e. , the subproblems always have optimal solutions. The new algorithm has two important properties. The computation of revision parameter for guaranteeing the consistency of quadratic subproblem and the computation of the second order correction step for superlinear convergence use the same inverse of a matrix per iteration, so the computation amount of the new algorithm will not be increased much more than other SQP type algorithms; Another is that the new algorithm can give automatically a feasible point as a starting point for the quadratic subproblems per iteration, this will obivously simplify the computation procedure of the subproblems. Some numerical results are reported.
文摘An apparent wave velocity varying with the frequency of seismic wave was adopted rather than an arbitrary one. The phase difference spectrum was introduced to consider the non-stationary properties of frequency contents in simulating artificial random field. The non-stationary random field on hard site considering the temporal-spatial variation was simulated by the way of spectral representation method. This random field can be used as the input of earthquake ground motion of the seismic response analysis of large-span spatial structures considering the effect of multi-supported excitation.
基金Project supported by the National Natural Science Foundation of China(No.29992530).
文摘The synthesis, characterization and electroluminescence performance of a new type of conjugatedpolymer, poly(2,5-diphenyl-1,3,4-thiadiazolyl)-4,4'-vinylene (TPPV) are presented. A light-emitting diodeconsisted of ITO/TPPV/Al is driven at about 4.0 V and has a peak emission wavelength of 485 nm. Thisblue-shift of the peak is due to the decrease of conjugate degree of TPPV compared to PPV. This result is inaccord with that determined by XPS and theoretical model of MNDO/3
基金The project supported by National Basic Research Project "Nonlinear Science" and National Natural Science Foundation of China under Grant No. 60074020
文摘A new nonlinear prediction technique is proposed by feedforward neural network, the learning algorithmfor network is a chaotic one. A timc-delay embedding is used to reconstruct the underlying attractor, the predictionmodel is based on the time evolution of the topological neighboring in the phase space, the spatial neighbors are chosenby the rate of exponential divergence of close trajectory. The model is tested for the Mackey-Glass delay equation andLorentz equations, good results are obtained for the prediction.
