We show that the Wigner function (an ensemble average of the density operator ρ, Δ is the Wigner operator) can be expressed as a matrix element of ρ in the entangled pure states. In doing so, converting from quant...We show that the Wigner function (an ensemble average of the density operator ρ, Δ is the Wigner operator) can be expressed as a matrix element of ρ in the entangled pure states. In doing so, converting from quantum master equations to time-evolution equation of the Wigner functions seems direct and concise. The entangled states are defined in the enlarged Fock space with a fictitious freedom.展开更多
The analytical expressions of the matrix elements for physical quantities are obtained for the Dirac oscillator in two and three spatial dimensions. Their behaviour for the case, of operator's square is discussed ...The analytical expressions of the matrix elements for physical quantities are obtained for the Dirac oscillator in two and three spatial dimensions. Their behaviour for the case, of operator's square is discussed in details. The two-dimensional Dirac oscillator has similar behavior to that for three-dimensional one.展开更多
Making use of the transformation relation among usual, normal, and antinormal ordering for the multimode boson exponential quadratic polynomial operators （BEQPO＇s）I we present the analytic expression of arbitrary m...Making use of the transformation relation among usual, normal, and antinormal ordering for the multimode boson exponential quadratic polynomial operators （BEQPO＇s）I we present the analytic expression of arbitrary matrix elements for BEQPO＇s. As a preliminary application, we obtain the exact expressions of partition function about the boson quadratic polynomial system, matrix elements in particle-number, coordinate, and momentum representation, and P representation for the BEQPO＇s.展开更多
We present analytical method to calculate single particle matrix elements used in atomic and nuclear physics. We show seven different formulas of matrix elements of the operator f(r)d_r^m where f(r) = r~μ, r~μjJ(qr)...We present analytical method to calculate single particle matrix elements used in atomic and nuclear physics. We show seven different formulas of matrix elements of the operator f(r)d_r^m where f(r) = r~μ, r~μjJ(qr), V(r)corresponding to the Gaussian and the Yukawa potentials used in nuclear shell models and nuclear structure. In addition,we take into account a general integral formula of the matrix element 〈 n′ l′|f(r) d_r^(m) |n l〉 that covers all seven matrix elements obtained analytically.展开更多
In this paper, the general calculation formulas of radial matrix elements for relativistic n-dimensional hydrogen atom of spin S=0 are obtained, and the recurrence relation of different power order radial matrix eleme...In this paper, the general calculation formulas of radial matrix elements for relativistic n-dimensional hydrogen atom of spin S=0 are obtained, and the recurrence relation of different power order radial matrix elements are also derived.展开更多
We present an analysis of a recent approach for determining the average pairing matrix elements within a specified interval of single-particle(sp)states around the Fermi level,denoted asλ.This method,known as the uni...We present an analysis of a recent approach for determining the average pairing matrix elements within a specified interval of single-particle(sp)states around the Fermi level,denoted asλ.This method,known as the uniform gap method(UGM),highlights the critical importance of the averaged sp level density.The pairing matrix elements within the UGM approach are deduced from microscopically calculated values of and gaps obtained from analytical formulae of a semi-classical nature.Two effects generally ignored in similar fits are addressed:(a)a correction for a systematic bias introduced by fitting pairing gaps corresponding to equilibrium deformation solutions,as discussed by Möller and Nix[Nucl.Phys.A 476,1(1992)],and(b)a correction for a systematic spurious enhancement of for protons in the vicinity ofλ,caused by the local Slater approximation commonly employed in treating Coulomb exchange terms(e.g.,[Phys.Rev.C 84,014310(2011)]).This approach has demonstrated significant efficiency when applied to Hartree-Fock+Bardeen-Cooper-Schrieffer(BCS)calculations(including the seniority force and self-consistent blocking for odd nuclei)of a large sample of well and rigidly deformed even-even rare-earth nuclei.The experimental moments of inertia for these nuclei were reproduced with an accuracy comparable to that achieved through direct fitting of the data[Phys.Rev.C 99,064306(2019)].In this study,we extended the evaluation of our method to the reproduction of three-point odd-even mass differences centered on odd-N or odd-Z nuclei in the same region.The agreement with experimental data was found to be comparable to that obtained through direct fitting,as reported in[Phys.Rev.C 99,064306(2019)].展开更多
The matrix elements along the reduction chain Sp(12,R)⊃SU(1,1)⊗SO(6)⊃U(1)⊗SUpn(3)⊗SO(2)⊃SO(3)of the proton-neutron symplectic model(PNSM)are considered.Closed analytical expressions are obtained for the matrix element...The matrix elements along the reduction chain Sp(12,R)⊃SU(1,1)⊗SO(6)⊃U(1)⊗SUpn(3)⊗SO(2)⊃SO(3)of the proton-neutron symplectic model(PNSM)are considered.Closed analytical expressions are obtained for the matrix elements of the basic building blocks of the PNSM and the Sp(12,R)symplectic generators,allowing the computation of matrix elements of other physical operators as well.The computational technique developed in the present study generally provides us with the required algebraic tool for performing realistic symplectic-based shell-model calculations of nuclear collective excitations.Utilizing two simple examples,we illustrate the application of the theory.展开更多
As a successive work of our previous paper, 1 the electron transfer matrix element (V rp) in the oxidation of the simplified model molecule of α-amino carbon-centered radical by O 2 has been investigated wi...As a successive work of our previous paper, 1 the electron transfer matrix element (V rp) in the oxidation of the simplified model molecule of α-amino carbon-centered radical by O 2 has been investigated with ab initio calculation at the level of UHF/6-31++G**. Based on the optimized geometries of the reactant and the ion-pair complex obtained previously, the reaction heat and the inner reorganization energy have been obtained by constructing the potential energy curves of reactant and product states considering the solvent effect with the conductor-like screening model (COSMO). The solvent reorganization energy has been estimated using Lippert-Mataga relationship. The calculated results show that the value of V rp is several times larger than that of RT, which means that the model reaction is an adiabatic one. Theoretical investigation indicates that the solvent effect on the direct electron transfer (ET) process of oxidation of α-amino carbon-centered radical by oxygen is remarkable.展开更多
In this work,the characteristics of 2νββ decays for six nuclei(36Ar,46Ca,48Ca,50Cr,70Zn,and 136Xe)in a mass range from A=36 to A=136 are studied within the nuclear shell model(NSM)framework.Calculations are present...In this work,the characteristics of 2νββ decays for six nuclei(36Ar,46Ca,48Ca,50Cr,70Zn,and 136Xe)in a mass range from A=36 to A=136 are studied within the nuclear shell model(NSM)framework.Calculations are presented for the half-lives,nuclear matrix elements(NMEs),phase space factors(G2ν),and convergence of the NMEs.The theoretical results agree well with the experimental data.In addition,we predict the half-lives of 2νββ decays for four nuclei.We focus on the convergence of the NMEs by analyzing the number of contributing intermediate 1+states(NC)for the nuclei of interest.We assume that NC is safely determined when the accumulated NMEs saturate 99.7%of the final calculated magnitude.From the calculations of the involved nuclei,we discover a connection between NC and the total number of intermediate 1+states(NT).According to the least squares fit,we conclude that the correlation is NC=(10.8±1.2)×N(0.29±0.02)T.展开更多
On the basis of the common feature among the electron transfer process and the ion hydration process as well as the relevant experimental kinetic data of electron trader reaction, a new accurate hydration potential fu...On the basis of the common feature among the electron transfer process and the ion hydration process as well as the relevant experimental kinetic data of electron trader reaction, a new accurate hydration potential function scheme for the determination of electron transfer coupling matrix element is presented. The coupling matrix element between two hydrated ions of the reacting system in solution is calculated. The results and the applicability of this scheme are discussed.展开更多
Due to the non-stationary characteristics of vibration signals acquired from rolling element bearing fault, thc time-frequency analysis is often applied to describe the local information of these unstable signals smar...Due to the non-stationary characteristics of vibration signals acquired from rolling element bearing fault, thc time-frequency analysis is often applied to describe the local information of these unstable signals smartly. However, it is difficult to classitythe high dimensional feature matrix directly because of too large dimensions for many classifiers. This paper combines the concepts of time-frequency distribution（TFD） with non-negative matrix factorization（NMF）, and proposes a novel TFD matrix factorization method to enhance representation and identification of bearing fault. Throughout this method, the TFD of a vibration signal is firstly accomplished to describe the localized faults with short-time Fourier transform（STFT）. Then, the supervised NMF mapping is adopted to extract the fault features from TFD. Meanwhile, the fault samples can be clustered and recognized automatically by using the clustering property of NMF. The proposed method takes advantages of the NMF in the parts-based representation and the adaptive clustering. The localized fault features of interest can be extracted as well. To evaluate the performance of the proposed method, the 9 kinds of the bearing fault on a test bench is performed. The proposed method can effectively identify the fault severity and different fault types. Moreover, in comparison with the artificial neural network（ANN）, NMF yields 99.3% mean accuracy which is much superior to ANN. This research presents a simple and practical resolution for the fault diagnosis problem of rolling element bearing in high dimensional feature space.展开更多
The consolidation process of SiC<sub>f</sub>/Ti-6Al-4V composites by matrix-coated fiber (MCF) method via hot pressing was investigated using finite element modeling (FEM). By analyzing the elastic–plasti...The consolidation process of SiC<sub>f</sub>/Ti-6Al-4V composites by matrix-coated fiber (MCF) method via hot pressing was investigated using finite element modeling (FEM). By analyzing the elastic–plastic contact deformation of the representative aligned coated fibers, the consolidation maps delineating the time–temperature–pressure relationship for full densification were constructed. Both the flow coefficient and the contact area coefficient used to describe the contact deformation were calculated according to the model. In addition, the effect of fiber content on matrix stress distribution was analyzed. The results show that fiber content is a significant factor that influences the densification process. Higher fiber content will lower the consolidation rate.展开更多
Based on the interphase layer model and the spring layer model, an improved interface model was developed to evaluate the interfacial shear strength of Titanium matrix composites(TMCs) and to analyze the effects of va...Based on the interphase layer model and the spring layer model, an improved interface model was developed to evaluate the interfacial shear strength of Titanium matrix composites(TMCs) and to analyze the effects of various parameters on the interfacial properties. The results showed that the improved interface model is more suitable for calculating the interfacial properties of SiC fiber reinforced titanium matrix composites. The interfacial shear strength of SiC/Timetal-834 predicted is 500 MPa. In addition, in order to better understand the interfacial properties of composites, some push out phenomenon were analyzed.展开更多
Ⅰ. INTRODUCTIONRecently, Zheng suggested a new model potential to describe the electronic motion in a multi-electron atom or ion in his serial papers. Applying this new version of model po-
Nuclear matrix elements(NME) and phase space factors(PSF) entering the half-life formulas of the double-beta decay(DBD) process are two key quantities whose accurate computation still represents a challenge. In this s...Nuclear matrix elements(NME) and phase space factors(PSF) entering the half-life formulas of the double-beta decay(DBD) process are two key quantities whose accurate computation still represents a challenge. In this study, we propose a new approach of calculating these, namely the direct computation of their product as an unique formula. This procedure allows a more coherent treatment of the nuclear approximations and input parameters appearing in both quantities and avoids possible confusion in the interpretation of DBD data due to different individual expressions adopted for PSF and NME(and consequently their reporting in different units) by different authors. Our calculations are performed for both two neutrino(2 vββ) and neutrinoless(0 vββ) decay modes, for five nuclei of the most experimental interest. Further, using the most recent experimental limits for 0νββ decay half-lives,we provide new constraints on the light mass neutrino parameter. Finally, by separating the factor representing the axial-vector constant to the forth power in the half-life formulas, we advance suggestions on how to reduce the errors introduced in the calculation by the uncertain value of this constant, exploiting the DBD data obtained from different isotopes and/or decay modes.展开更多
Element stiffness equation is very important in structural analysis, and directly influences the accuracy of the results. At present, derivation method of element stiffness equation is relatively mature under ambient ...Element stiffness equation is very important in structural analysis, and directly influences the accuracy of the results. At present, derivation method of element stiffness equation is relatively mature under ambient temperature, and the elastic phrase of material stress-strain curve is generally adopted as physical equation in derivation. However, the material stress-strain relationship is very complicated at elevated temperature, and its form is not unique, which brings great difficulty to the derivation of element stiffness equation. Referring to the derivation method of element stiffness equation at ambient temperature, by using the continuous function of stress-strain-temperature at elevated temperature, and based on the principle of virtual work, the stiffness equation of space beam element and the formulas of stiffness matrix are derived in this paper, which provide basis for finite element analysis on structures at elevated temperature.展开更多
Effects of rare earth element La on the microstructure of Cumatrix diamond tools were researched under the conditions of variousmaterials components and the process parameters in order to improvematerials properties. ...Effects of rare earth element La on the microstructure of Cumatrix diamond tools were researched under the conditions of variousmaterials components and the process parameters in order to improvematerials properties. SEM, XPS and X-ray were used to investigate thefracture section, microstructure and the element valence inmaterials. The Results shown that the combination of rare earthelement La and transition element Ti is advantageous to the bondingstate Between diamond particles and matrix, so it can improve thematerials properties. Suitable sintering temperature is 790 deg. C.展开更多
The dynamic deformation of harmonic vibration is used as the shape functions of the finite annular plate element, and sonic integration difficulties related to the Bessel's functions are solved in this paper. Then...The dynamic deformation of harmonic vibration is used as the shape functions of the finite annular plate element, and sonic integration difficulties related to the Bessel's functions are solved in this paper. Then the dynamic stiffness matrix of the finite annular plate element is established in closed form and checked by the direct stiffness method. The paper has given wide convcrage for decomposing the dynamic matrix into the power series of frequency square. By utilizing the axial symmetry of annular elements, the modes with different numbers of nodal diameters at s separately treated. Thus some terse and complete results are obtained as the foundation of structural characteristic analysis and dynamic response compulation.展开更多
The influence of the shape and spatial distribution of reinforced particles on strength and damage of metal matrix composite （MMC） is investigated through finite element method under uniaxial tensile, simple shear, ...The influence of the shape and spatial distribution of reinforced particles on strength and damage of metal matrix composite （MMC） is investigated through finite element method under uniaxial tensile, simple shear, biaxial tensile, as well as combined tensile/shear loadings. The particle shapes change randomly from circular to regular n-sided polygon （3 ≤ n ≤ 10）; the particle alignments are determined through a sequentially random number stream and the particle locations are defined through the random sequential adsorption algorithm. The ductile failure in metal matrix and brittle failure in particles are described through damage models based on the stress triaxial indicator and maximum principal stress criterion, respectively, while the debonding behavior of interface between particles and matrix is simulated through cohesive elements. The simulation results show that, under different loadings, interface debonding is the dominated failure mechanism in MMCs and plastic deformation and ductile failure of matrix also play very important roles on the failure of MMCs.展开更多
Using Stricklin Melhod￣[5],we have this paper has derived the formulas for the ge-neration of non-linear element stiffness matrix of a triangle element when considering both the bending and the in-plane membrane forc...Using Stricklin Melhod￣[5],we have this paper has derived the formulas for the ge-neration of non-linear element stiffness matrix of a triangle element when considering both the bending and the in-plane membrane forces. A computer programme for the calculation of large deflection and inner forces of shallow shells is designed on theseformulas. The central deflection curve computed by this programme is compared with other pertaining results.展开更多
文摘We show that the Wigner function (an ensemble average of the density operator ρ, Δ is the Wigner operator) can be expressed as a matrix element of ρ in the entangled pure states. In doing so, converting from quantum master equations to time-evolution equation of the Wigner functions seems direct and concise. The entangled states are defined in the enlarged Fock space with a fictitious freedom.
基金The project supported by the Research Fund for the Doctorial Program of Higher Education of China under Grant No.20010284036+2 种基金National Natural Science Foundation of China under Grant No.10125521the 973 State Basic Key Research and Development of China under Grant No.G20000077400
文摘The analytical expressions of the matrix elements for physical quantities are obtained for the Dirac oscillator in two and three spatial dimensions. Their behaviour for the case, of operator's square is discussed in details. The two-dimensional Dirac oscillator has similar behavior to that for three-dimensional one.
基金The authors would like to thank Prof. Y.D. Zhang for selfless helps and valuable discussions.
文摘Making use of the transformation relation among usual, normal, and antinormal ordering for the multimode boson exponential quadratic polynomial operators （BEQPO＇s）I we present the analytic expression of arbitrary matrix elements for BEQPO＇s. As a preliminary application, we obtain the exact expressions of partition function about the boson quadratic polynomial system, matrix elements in particle-number, coordinate, and momentum representation, and P representation for the BEQPO＇s.
文摘We present analytical method to calculate single particle matrix elements used in atomic and nuclear physics. We show seven different formulas of matrix elements of the operator f(r)d_r^m where f(r) = r~μ, r~μjJ(qr), V(r)corresponding to the Gaussian and the Yukawa potentials used in nuclear shell models and nuclear structure. In addition,we take into account a general integral formula of the matrix element 〈 n′ l′|f(r) d_r^(m) |n l〉 that covers all seven matrix elements obtained analytically.
文摘In this paper, the general calculation formulas of radial matrix elements for relativistic n-dimensional hydrogen atom of spin S=0 are obtained, and the recurrence relation of different power order radial matrix elements are also derived.
基金support by the Hue University under the Core Research Program,(NCM.DHH.2018.09)Universiti Teknologi Malaysia for its UTMShine grant(Q.J130000.2454.09G96)。
文摘We present an analysis of a recent approach for determining the average pairing matrix elements within a specified interval of single-particle(sp)states around the Fermi level,denoted asλ.This method,known as the uniform gap method(UGM),highlights the critical importance of the averaged sp level density.The pairing matrix elements within the UGM approach are deduced from microscopically calculated values of and gaps obtained from analytical formulae of a semi-classical nature.Two effects generally ignored in similar fits are addressed:(a)a correction for a systematic bias introduced by fitting pairing gaps corresponding to equilibrium deformation solutions,as discussed by Möller and Nix[Nucl.Phys.A 476,1(1992)],and(b)a correction for a systematic spurious enhancement of for protons in the vicinity ofλ,caused by the local Slater approximation commonly employed in treating Coulomb exchange terms(e.g.,[Phys.Rev.C 84,014310(2011)]).This approach has demonstrated significant efficiency when applied to Hartree-Fock+Bardeen-Cooper-Schrieffer(BCS)calculations(including the seniority force and self-consistent blocking for odd nuclei)of a large sample of well and rigidly deformed even-even rare-earth nuclei.The experimental moments of inertia for these nuclei were reproduced with an accuracy comparable to that achieved through direct fitting of the data[Phys.Rev.C 99,064306(2019)].In this study,we extended the evaluation of our method to the reproduction of three-point odd-even mass differences centered on odd-N or odd-Z nuclei in the same region.The agreement with experimental data was found to be comparable to that obtained through direct fitting,as reported in[Phys.Rev.C 99,064306(2019)].
文摘The matrix elements along the reduction chain Sp(12,R)⊃SU(1,1)⊗SO(6)⊃U(1)⊗SUpn(3)⊗SO(2)⊃SO(3)of the proton-neutron symplectic model(PNSM)are considered.Closed analytical expressions are obtained for the matrix elements of the basic building blocks of the PNSM and the Sp(12,R)symplectic generators,allowing the computation of matrix elements of other physical operators as well.The computational technique developed in the present study generally provides us with the required algebraic tool for performing realistic symplectic-based shell-model calculations of nuclear collective excitations.Utilizing two simple examples,we illustrate the application of the theory.
文摘As a successive work of our previous paper, 1 the electron transfer matrix element (V rp) in the oxidation of the simplified model molecule of α-amino carbon-centered radical by O 2 has been investigated with ab initio calculation at the level of UHF/6-31++G**. Based on the optimized geometries of the reactant and the ion-pair complex obtained previously, the reaction heat and the inner reorganization energy have been obtained by constructing the potential energy curves of reactant and product states considering the solvent effect with the conductor-like screening model (COSMO). The solvent reorganization energy has been estimated using Lippert-Mataga relationship. The calculated results show that the value of V rp is several times larger than that of RT, which means that the model reaction is an adiabatic one. Theoretical investigation indicates that the solvent effect on the direct electron transfer (ET) process of oxidation of α-amino carbon-centered radical by oxygen is remarkable.
基金Supported by National Natural Science Foundation of China(11647086,11647085)Shanxi Province Science Foundation for Youths(201901D211252)+1 种基金Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(2019L0554,2019L0505)the Natural Science Research Fund of North University of China(XJJ201811)。
文摘In this work,the characteristics of 2νββ decays for six nuclei(36Ar,46Ca,48Ca,50Cr,70Zn,and 136Xe)in a mass range from A=36 to A=136 are studied within the nuclear shell model(NSM)framework.Calculations are presented for the half-lives,nuclear matrix elements(NMEs),phase space factors(G2ν),and convergence of the NMEs.The theoretical results agree well with the experimental data.In addition,we predict the half-lives of 2νββ decays for four nuclei.We focus on the convergence of the NMEs by analyzing the number of contributing intermediate 1+states(NC)for the nuclei of interest.We assume that NC is safely determined when the accumulated NMEs saturate 99.7%of the final calculated magnitude.From the calculations of the involved nuclei,we discover a connection between NC and the total number of intermediate 1+states(NT).According to the least squares fit,we conclude that the correlation is NC=(10.8±1.2)×N(0.29±0.02)T.
基金Project (No. 29673025) supported by the National Natural Science Foundation of China
文摘On the basis of the common feature among the electron transfer process and the ion hydration process as well as the relevant experimental kinetic data of electron trader reaction, a new accurate hydration potential function scheme for the determination of electron transfer coupling matrix element is presented. The coupling matrix element between two hydrated ions of the reacting system in solution is calculated. The results and the applicability of this scheme are discussed.
基金Supported by Shaanxi Provincial Overall Innovation Project of Science and Technology,China(Grant No.2013KTCQ01-06)
文摘Due to the non-stationary characteristics of vibration signals acquired from rolling element bearing fault, thc time-frequency analysis is often applied to describe the local information of these unstable signals smartly. However, it is difficult to classitythe high dimensional feature matrix directly because of too large dimensions for many classifiers. This paper combines the concepts of time-frequency distribution（TFD） with non-negative matrix factorization（NMF）, and proposes a novel TFD matrix factorization method to enhance representation and identification of bearing fault. Throughout this method, the TFD of a vibration signal is firstly accomplished to describe the localized faults with short-time Fourier transform（STFT）. Then, the supervised NMF mapping is adopted to extract the fault features from TFD. Meanwhile, the fault samples can be clustered and recognized automatically by using the clustering property of NMF. The proposed method takes advantages of the NMF in the parts-based representation and the adaptive clustering. The localized fault features of interest can be extracted as well. To evaluate the performance of the proposed method, the 9 kinds of the bearing fault on a test bench is performed. The proposed method can effectively identify the fault severity and different fault types. Moreover, in comparison with the artificial neural network（ANN）, NMF yields 99.3% mean accuracy which is much superior to ANN. This research presents a simple and practical resolution for the fault diagnosis problem of rolling element bearing in high dimensional feature space.
基金financially supported by the National Natural Science Foundation of China(Nos.51071122 and51271147)
文摘The consolidation process of SiC<sub>f</sub>/Ti-6Al-4V composites by matrix-coated fiber (MCF) method via hot pressing was investigated using finite element modeling (FEM). By analyzing the elastic–plastic contact deformation of the representative aligned coated fibers, the consolidation maps delineating the time–temperature–pressure relationship for full densification were constructed. Both the flow coefficient and the contact area coefficient used to describe the contact deformation were calculated according to the model. In addition, the effect of fiber content on matrix stress distribution was analyzed. The results show that fiber content is a significant factor that influences the densification process. Higher fiber content will lower the consolidation rate.
基金Supported by the Natural Science Foundation of Chinathe Aviation Science Foundation of Chinathe Doctoral Innovation Foundation of Northwestern Polytechnical University
文摘Based on the interphase layer model and the spring layer model, an improved interface model was developed to evaluate the interfacial shear strength of Titanium matrix composites(TMCs) and to analyze the effects of various parameters on the interfacial properties. The results showed that the improved interface model is more suitable for calculating the interfacial properties of SiC fiber reinforced titanium matrix composites. The interfacial shear strength of SiC/Timetal-834 predicted is 500 MPa. In addition, in order to better understand the interfacial properties of composites, some push out phenomenon were analyzed.
文摘Ⅰ. INTRODUCTIONRecently, Zheng suggested a new model potential to describe the electronic motion in a multi-electron atom or ion in his serial papers. Applying this new version of model po-
基金Supported by Ministry of Research and Innovation through UEFISCDI,project PCE-2016-0078,contract 198/2017
文摘Nuclear matrix elements(NME) and phase space factors(PSF) entering the half-life formulas of the double-beta decay(DBD) process are two key quantities whose accurate computation still represents a challenge. In this study, we propose a new approach of calculating these, namely the direct computation of their product as an unique formula. This procedure allows a more coherent treatment of the nuclear approximations and input parameters appearing in both quantities and avoids possible confusion in the interpretation of DBD data due to different individual expressions adopted for PSF and NME(and consequently their reporting in different units) by different authors. Our calculations are performed for both two neutrino(2 vββ) and neutrinoless(0 vββ) decay modes, for five nuclei of the most experimental interest. Further, using the most recent experimental limits for 0νββ decay half-lives,we provide new constraints on the light mass neutrino parameter. Finally, by separating the factor representing the axial-vector constant to the forth power in the half-life formulas, we advance suggestions on how to reduce the errors introduced in the calculation by the uncertain value of this constant, exploiting the DBD data obtained from different isotopes and/or decay modes.
基金the National Natural Science Foundation of China(No.50578093)
文摘Element stiffness equation is very important in structural analysis, and directly influences the accuracy of the results. At present, derivation method of element stiffness equation is relatively mature under ambient temperature, and the elastic phrase of material stress-strain curve is generally adopted as physical equation in derivation. However, the material stress-strain relationship is very complicated at elevated temperature, and its form is not unique, which brings great difficulty to the derivation of element stiffness equation. Referring to the derivation method of element stiffness equation at ambient temperature, by using the continuous function of stress-strain-temperature at elevated temperature, and based on the principle of virtual work, the stiffness equation of space beam element and the formulas of stiffness matrix are derived in this paper, which provide basis for finite element analysis on structures at elevated temperature.
文摘Effects of rare earth element La on the microstructure of Cumatrix diamond tools were researched under the conditions of variousmaterials components and the process parameters in order to improvematerials properties. SEM, XPS and X-ray were used to investigate thefracture section, microstructure and the element valence inmaterials. The Results shown that the combination of rare earthelement La and transition element Ti is advantageous to the bondingstate Between diamond particles and matrix, so it can improve thematerials properties. Suitable sintering temperature is 790 deg. C.
文摘The dynamic deformation of harmonic vibration is used as the shape functions of the finite annular plate element, and sonic integration difficulties related to the Bessel's functions are solved in this paper. Then the dynamic stiffness matrix of the finite annular plate element is established in closed form and checked by the direct stiffness method. The paper has given wide convcrage for decomposing the dynamic matrix into the power series of frequency square. By utilizing the axial symmetry of annular elements, the modes with different numbers of nodal diameters at s separately treated. Thus some terse and complete results are obtained as the foundation of structural characteristic analysis and dynamic response compulation.
基金financially supported by the Fundamental Research Funds for the Central Universities (No.NE2014401)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘The influence of the shape and spatial distribution of reinforced particles on strength and damage of metal matrix composite （MMC） is investigated through finite element method under uniaxial tensile, simple shear, biaxial tensile, as well as combined tensile/shear loadings. The particle shapes change randomly from circular to regular n-sided polygon （3 ≤ n ≤ 10）; the particle alignments are determined through a sequentially random number stream and the particle locations are defined through the random sequential adsorption algorithm. The ductile failure in metal matrix and brittle failure in particles are described through damage models based on the stress triaxial indicator and maximum principal stress criterion, respectively, while the debonding behavior of interface between particles and matrix is simulated through cohesive elements. The simulation results show that, under different loadings, interface debonding is the dominated failure mechanism in MMCs and plastic deformation and ductile failure of matrix also play very important roles on the failure of MMCs.
文摘Using Stricklin Melhod￣[5],we have this paper has derived the formulas for the ge-neration of non-linear element stiffness matrix of a triangle element when considering both the bending and the in-plane membrane forces. A computer programme for the calculation of large deflection and inner forces of shallow shells is designed on theseformulas. The central deflection curve computed by this programme is compared with other pertaining results.
