Inductively coupled channels are based on the electromagnetic induction principle and realize long-distance current signal transmission through seawater.Due to a few difficulties in performing actual experiments,it is...Inductively coupled channels are based on the electromagnetic induction principle and realize long-distance current signal transmission through seawater.Due to a few difficulties in performing actual experiments,it is unclear how the seawater medium affects the frequency selectivity of the current signal.In this paper,a dual dipole model of the inductively coupled seawater transmission channel is established for the traditional short-distance current field transmission mode.The transmission characteristics of electrical signals in seawater are theoretically derived.A platform is used to measure the amplitude-frequency and phase-frequency characteristics of the current signal transmission in seawater with transmission frequencies ranging from 30 kHz to 1 MHz,and transmission distances in the vertical range of 4 m.The COMSOL Multiphysics simulation and practical test analysis are carried out to analyze the frequency selectivity of seawater conductivity.It is proved that the seawater resistance increases as the frequency increases,which is the key problem that affects the current signal.This study provides an important theoretical support and experimental evidence for improving the transmission performance of long-distance underwater current signals.展开更多
In this contribution,we introduce numerical continuation methods and bifurcation theory,techniques which find their roots in the study of dynamical systems,to the problem of tracing the parameter dependence of bound a...In this contribution,we introduce numerical continuation methods and bifurcation theory,techniques which find their roots in the study of dynamical systems,to the problem of tracing the parameter dependence of bound and resonant states of the quantum mechanical Schrodinger equation.We extend previous work on the subject[1]to systems of coupled equations.Bound and resonant states of the Schrodinger equation can be determined through the poles of the S-matrix,a quantity that can be derived from the asymptotic form of the wave function.We introduce a regularization procedure that essentially transforms the S-matrix into its inverse and improves its smoothness properties,thus making it amenable to numerical continuation.This allows us to automate the process of tracking bound and resonant states when parameters in the Schrodinger equation are varied.We have applied this approach to a number of model problems with satisfying results.展开更多
We present a systematic study of 6Li elastic scattering and total reaction cross sections at incident energies around the Coulomb barrier within the continuum discretized coupled-channels(CDCC)framework,where 6Li is t...We present a systematic study of 6Li elastic scattering and total reaction cross sections at incident energies around the Coulomb barrier within the continuum discretized coupled-channels(CDCC)framework,where 6Li is treated in anα+d two-body model.Collisions with 27Al,64Zn,138Ba,and 208Pa are analyzed.The microscopic optical potentials(MOP)based on Skyrme nucleon-nucleon interaction forαand d are adopted in CDCC calculations and satisfactory agreement with the experimental data is obtained without any adjustment on MOPs.For comparison,αand d global phenomenological optical potentials(GOP)are also used in CDCC analysis and a reduction of no less than 50%on the surface imaginary part of deuteron GOP is required for describing the data.In all cases,the 6Li breakup effect is significant and provides repulsive correction to the folding model potential.The reduction on the surface imaginary part of GOP of deuteron reveals a strong suppression of the reaction probability of deuteron as a component of 6Li when compared with that of a free deuteron.Further investigation is performed by considering the d breakup process equivalently within the dynamic polarization potential approach,and the results show that d behaves in a manner similar to a tightly bound nucleus in 6Li induced reactions.展开更多
Based on the importance of fractured rock mass seepage research, in order to analyze seepage flow characteristics of collapse column under the influence of mining, a method by embedding fractured rock mass flow solid ...Based on the importance of fractured rock mass seepage research, in order to analyze seepage flow characteristics of collapse column under the influence of mining, a method by embedding fractured rock mass flow solid coupling relationship into FLAC3D internal flow models is presented according to fluid-solid coupling theory and strength criterion. A calculation model of numerical analysis was established, and the influences of mining pressure and plastic damage to pore water pressure and seepage vector change rule were studied. The results show that collapse column is the main channel of confined water seepage upward. The impact is not big when the workface is away from the collapse column. But when the workface is nearing a collapse column, there will be a seepage channel on a side near the workface, in which seepage vector and head are comparatively large. With workface pushing through collapse column, the seepage channel transfers to the other side of the column. In addition, when the plastic damage area within the collapse column breaks through, a "pipeline flow" will be formed within the column, and seepage field will change remarkably and the possibility of water bursting will be greater.展开更多
The latest progress made in the field of radioactive ion beam physics is outlined and the key problems still under investigation are indicated. The focal points are the limit of nuclear existence, shell evolution and ...The latest progress made in the field of radioactive ion beam physics is outlined and the key problems still under investigation are indicated. The focal points are the limit of nuclear existence, shell evolution and new magic numbers, halo and cluster structures, new excitation modes, and strong coupling between reaction channels. This field is still at a starting phase and much more new outcomes are foreseen.展开更多
Controversies exist among experiments and theories on the S^(*)factor of the astrophysical important reaction ^(12)C+^(12)C for energies below 3 MeV.Only frequentist approaches have been used so far for data analysis,...Controversies exist among experiments and theories on the S^(*)factor of the astrophysical important reaction ^(12)C+^(12)C for energies below 3 MeV.Only frequentist approaches have been used so far for data analysis,and the confidence levels or theoretical errors are not available from previous theoretical predictions.In this study,the Bayesian method is employed to provide theoretical predictions and its 1σconfidence level based on all the currently available experimental data for the first time.The improved coupled-channels model CCFULL-FEM implemented with the finite element method as well as the Markov chain Monte Carlo approach emcee are adopted to analyze the non-resonant behavior of this reaction.The posterior distribution of the Woods-Saxon potential parameters is investigated.Compared with the widely used frequentist method MIGRAD within the Minuit minimization program,the Bayesian method has a significant advantage for exploring the potential parameter space.When the existing experimental data measured down to subbarrier energies are considered,the potential parameters are constrained to a very narrow range,and the predictions of the S^(*) factor showed no sharp decrease in the low-energy region.展开更多
This article analyzes the fusion dynamics of loosely bound and stable projectiles with Zr-target isotopes within the context of the coupled channel approach and the energy-dependent Woods-Saxon potential model （EDWSP...This article analyzes the fusion dynamics of loosely bound and stable projectiles with Zr-target isotopes within the context of the coupled channel approach and the energy-dependent Woods-Saxon potential model （EDWSP model）. In the case of the 2SSi＋90Zr reaction, the coupling to the inelastic surface excitations results in an adequate description of the observed fusion dynamics while in case of the 2Ssi ＋ 94Zr reaction, the coupling to collective surface vibrational states as well as the neutron （multi-neutron） transfer channel is necessary in the coupled channel calculations to reproduce the below-barrier fusion data. However, the EDWSP model calculation provides an accurate explanation of the fusion data of 2Ssi＋ 90,94Zr reactions in the domain of the Coulomb barrier. In the fusion of the 6Li＋90Zr reaction, the inclusion of the nuclear structure degrees of freedom recovers the observed sub-barrier fusion enhancement but results in suppression of the above barrier fusion data by 34% with respect to the coupled channel calculations. Using EDWSP model calculations, this suppression factor is reduced by 14% and consequently, the above-barrier fusion data of 6Li＋90Zr reaction is suppressed by 20% with reference to the EDWSP model calculations. Such fusion suppression at above-barrier energies can be correlated with the breakupof the projectile （6Li） before reaching the fusion barrier, as a consequence of low binding energy.展开更多
To obtain the neutron spectroscopic amplitudes for 90-96Zx overlaps experimental data of elastic scatter-ing with small experimental errors and precise optical potentals were anary exin othe hiohpyecision o3D magnetic...To obtain the neutron spectroscopic amplitudes for 90-96Zx overlaps experimental data of elastic scatter-ing with small experimental errors and precise optical potentals were anary exin othe hiohpyecision o3D magneticangular distributions of^12,^13C+^AZr(A=90,91,92,94,96)were measured using the high-precision Q3D magnetic spectrometer in the Tandem accelerator.The Sao Paulo potential was used for the optical potential.The optical mod-el and coupled channel calculations were compared with the experimental data.The theoretical results were found tobe very close to the experimental data.In addition,the possible effects of the couplings to the inelastic channels of the^AZr targets and 12,13^C projectiles on the elastic scattering were studied.It was observed that the couplings to the in-elastic channels of the^12,^13C projectiles could improve the agreement with the experimental data,while the inelasticcouplings to the target states are of minor importance.The effect of the one-neutron stripping in the^13C+^AZr elasticscattering was also studied.The one-neutron stripping channel in^13C+^AZr was found to be not relevant and did notaffect the elastic scattering angular distributions.Our results also show that in the reactions with the considered zir-conium isotopes,the presence of the extra neutron in^13C does not influence the reaction mechanism,which is gov-erned by the collective excitation of the^12C core.展开更多
In this work, Rotation model and rotation vibration coupled channel optical model (CCOM) were first used to carry out systematic calculation of neutron direct inelastic scattering cross section (DISCS) for the reacti...In this work, Rotation model and rotation vibration coupled channel optical model (CCOM) were first used to carry out systematic calculation of neutron direct inelastic scattering cross section (DISCS) for the reaction 238 U (n,n′) with an incident energy from 0 01 MeV to 20 0 MeV . The number of coupled energy levels involved in this calculation increased to eight at the first time, namely 0 +, 2 +, 4 +, 6 +, 8 + in the ground rotation band of 238 U and 1 -, 3 -, 5 - in the octupole vibration band with K=0 -. Some physical problems, such as how to get the optical model parameters of deformed nuclei and phonon amplitudes, are discussed.展开更多
The dynamic coupling effects on fusion cross sections for reactions^(32)S + ^(94,96)Zr and ^(40)Ca + ^(94,96)Zr are studied with the universal fusion function formalism and an empirical coupled channel(ECC) model. An ...The dynamic coupling effects on fusion cross sections for reactions^(32)S + ^(94,96)Zr and ^(40)Ca + ^(94,96)Zr are studied with the universal fusion function formalism and an empirical coupled channel(ECC) model. An examination of the reduced fusion functions shows that the total effect of couplings to inelastic excitations and neutron transfer channels on fusion in ^(32)S +^(94)Zr(^(40)Ca +^(94)Zr) is almost the same as that in ^(32)S +^(96)Zr(^(40)Ca +^(96)Zr). The enhancements of the fusion cross section at sub-barrier energies due to inelastic channel coupling and neutron transfer channel coupling are evaluated separately by using the ECC model. The results show that effect of couplings to inelastic excitations channels in the reactions with94 Zr as target should be similar as that in the reactions with ^(96) Zr as target. This implies that the quadrupole deformation parameters β_2of ^(94)Zr and^(96) Zr should be similar to each other.However, β_2 's predicted from the finite-range droplet model, which are used in the ECC model, are quite different. Experiments on^(48) Ca +^(94)Zr or^(36) S +^(94)Zr are suggested to solve the puzzling issue concerning β_2for^(94)Zr.展开更多
文摘Inductively coupled channels are based on the electromagnetic induction principle and realize long-distance current signal transmission through seawater.Due to a few difficulties in performing actual experiments,it is unclear how the seawater medium affects the frequency selectivity of the current signal.In this paper,a dual dipole model of the inductively coupled seawater transmission channel is established for the traditional short-distance current field transmission mode.The transmission characteristics of electrical signals in seawater are theoretically derived.A platform is used to measure the amplitude-frequency and phase-frequency characteristics of the current signal transmission in seawater with transmission frequencies ranging from 30 kHz to 1 MHz,and transmission distances in the vertical range of 4 m.The COMSOL Multiphysics simulation and practical test analysis are carried out to analyze the frequency selectivity of seawater conductivity.It is proved that the seawater resistance increases as the frequency increases,which is the key problem that affects the current signal.This study provides an important theoretical support and experimental evidence for improving the transmission performance of long-distance underwater current signals.
文摘In this contribution,we introduce numerical continuation methods and bifurcation theory,techniques which find their roots in the study of dynamical systems,to the problem of tracing the parameter dependence of bound and resonant states of the quantum mechanical Schrodinger equation.We extend previous work on the subject[1]to systems of coupled equations.Bound and resonant states of the Schrodinger equation can be determined through the poles of the S-matrix,a quantity that can be derived from the asymptotic form of the wave function.We introduce a regularization procedure that essentially transforms the S-matrix into its inverse and improves its smoothness properties,thus making it amenable to numerical continuation.This allows us to automate the process of tracking bound and resonant states when parameters in the Schrodinger equation are varied.We have applied this approach to a number of model problems with satisfying results.
基金Supported by the National Natural Science Foundation of China(U2067205)。
文摘We present a systematic study of 6Li elastic scattering and total reaction cross sections at incident energies around the Coulomb barrier within the continuum discretized coupled-channels(CDCC)framework,where 6Li is treated in anα+d two-body model.Collisions with 27Al,64Zn,138Ba,and 208Pa are analyzed.The microscopic optical potentials(MOP)based on Skyrme nucleon-nucleon interaction forαand d are adopted in CDCC calculations and satisfactory agreement with the experimental data is obtained without any adjustment on MOPs.For comparison,αand d global phenomenological optical potentials(GOP)are also used in CDCC analysis and a reduction of no less than 50%on the surface imaginary part of deuteron GOP is required for describing the data.In all cases,the 6Li breakup effect is significant and provides repulsive correction to the folding model potential.The reduction on the surface imaginary part of GOP of deuteron reveals a strong suppression of the reaction probability of deuteron as a component of 6Li when compared with that of a free deuteron.Further investigation is performed by considering the d breakup process equivalently within the dynamic polarization potential approach,and the results show that d behaves in a manner similar to a tightly bound nucleus in 6Li induced reactions.
基金the financial support for this work by the National Key Basic Research and Development Program of China (No. 2010CB226805)the National Natural Science Foundation of China (No. 0874103)the Natural Science Foundation of Jiangsu Province (No. BK2008135)
文摘Based on the importance of fractured rock mass seepage research, in order to analyze seepage flow characteristics of collapse column under the influence of mining, a method by embedding fractured rock mass flow solid coupling relationship into FLAC3D internal flow models is presented according to fluid-solid coupling theory and strength criterion. A calculation model of numerical analysis was established, and the influences of mining pressure and plastic damage to pore water pressure and seepage vector change rule were studied. The results show that collapse column is the main channel of confined water seepage upward. The impact is not big when the workface is away from the collapse column. But when the workface is nearing a collapse column, there will be a seepage channel on a side near the workface, in which seepage vector and head are comparatively large. With workface pushing through collapse column, the seepage channel transfers to the other side of the column. In addition, when the plastic damage area within the collapse column breaks through, a "pipeline flow" will be formed within the column, and seepage field will change remarkably and the possibility of water bursting will be greater.
基金supported by National Basic Research Program of China (No.2007CB815002)National Natural Science Foundation of China(Nos.11035001,10775003,10827505,10821140159)
文摘The latest progress made in the field of radioactive ion beam physics is outlined and the key problems still under investigation are indicated. The focal points are the limit of nuclear existence, shell evolution and new magic numbers, halo and cluster structures, new excitation modes, and strong coupling between reaction channels. This field is still at a starting phase and much more new outcomes are foreseen.
基金Supported by the National Natural Science Foundation of China(11635015,11805280,U1732145,11705285,U1867212,11961131012)the Continuous Basic Scientific Research Project(WDJC-2019-13)+1 种基金the Young Talent Development Foundation(YC212212000101)the Leading Innovation Project(LC192209000701,LC202309000201)。
文摘Controversies exist among experiments and theories on the S^(*)factor of the astrophysical important reaction ^(12)C+^(12)C for energies below 3 MeV.Only frequentist approaches have been used so far for data analysis,and the confidence levels or theoretical errors are not available from previous theoretical predictions.In this study,the Bayesian method is employed to provide theoretical predictions and its 1σconfidence level based on all the currently available experimental data for the first time.The improved coupled-channels model CCFULL-FEM implemented with the finite element method as well as the Markov chain Monte Carlo approach emcee are adopted to analyze the non-resonant behavior of this reaction.The posterior distribution of the Woods-Saxon potential parameters is investigated.Compared with the widely used frequentist method MIGRAD within the Minuit minimization program,the Bayesian method has a significant advantage for exploring the potential parameter space.When the existing experimental data measured down to subbarrier energies are considered,the potential parameters are constrained to a very narrow range,and the predictions of the S^(*) factor showed no sharp decrease in the low-energy region.
基金Supported by Dr.D.S.Kothari Post-Doctoral Fellowship Scheme sponsored by University Grants Commission(UGC),New Delhi,India
文摘This article analyzes the fusion dynamics of loosely bound and stable projectiles with Zr-target isotopes within the context of the coupled channel approach and the energy-dependent Woods-Saxon potential model （EDWSP model）. In the case of the 2SSi＋90Zr reaction, the coupling to the inelastic surface excitations results in an adequate description of the observed fusion dynamics while in case of the 2Ssi ＋ 94Zr reaction, the coupling to collective surface vibrational states as well as the neutron （multi-neutron） transfer channel is necessary in the coupled channel calculations to reproduce the below-barrier fusion data. However, the EDWSP model calculation provides an accurate explanation of the fusion data of 2Ssi＋ 90,94Zr reactions in the domain of the Coulomb barrier. In the fusion of the 6Li＋90Zr reaction, the inclusion of the nuclear structure degrees of freedom recovers the observed sub-barrier fusion enhancement but results in suppression of the above barrier fusion data by 34% with respect to the coupled channel calculations. Using EDWSP model calculations, this suppression factor is reduced by 14% and consequently, the above-barrier fusion data of 6Li＋90Zr reaction is suppressed by 20% with reference to the EDWSP model calculations. Such fusion suppression at above-barrier energies can be correlated with the breakupof the projectile （6Li） before reaching the fusion barrier, as a consequence of low binding energy.
基金Supported by National Natural Science Foundation of China(U1832130,11975040 and 11475013)National Key R&D Program of China(2017YFF0106501)Brazilian financial support from CNPq,CAPES and FAPERJ and from INCT-FNA(Instituto Nacional de Ciência e Tecnologia-Física Nuclear e Aplicações)(464898/2014-5)。
文摘To obtain the neutron spectroscopic amplitudes for 90-96Zx overlaps experimental data of elastic scatter-ing with small experimental errors and precise optical potentals were anary exin othe hiohpyecision o3D magneticangular distributions of^12,^13C+^AZr(A=90,91,92,94,96)were measured using the high-precision Q3D magnetic spectrometer in the Tandem accelerator.The Sao Paulo potential was used for the optical potential.The optical mod-el and coupled channel calculations were compared with the experimental data.The theoretical results were found tobe very close to the experimental data.In addition,the possible effects of the couplings to the inelastic channels of the^AZr targets and 12,13^C projectiles on the elastic scattering were studied.It was observed that the couplings to the in-elastic channels of the^12,^13C projectiles could improve the agreement with the experimental data,while the inelasticcouplings to the target states are of minor importance.The effect of the one-neutron stripping in the^13C+^AZr elasticscattering was also studied.The one-neutron stripping channel in^13C+^AZr was found to be not relevant and did notaffect the elastic scattering angular distributions.Our results also show that in the reactions with the considered zir-conium isotopes,the presence of the extra neutron in^13C does not influence the reaction mechanism,which is gov-erned by the collective excitation of the^12C core.
文摘In this work, Rotation model and rotation vibration coupled channel optical model (CCOM) were first used to carry out systematic calculation of neutron direct inelastic scattering cross section (DISCS) for the reaction 238 U (n,n′) with an incident energy from 0 01 MeV to 20 0 MeV . The number of coupled energy levels involved in this calculation increased to eight at the first time, namely 0 +, 2 +, 4 +, 6 +, 8 + in the ground rotation band of 238 U and 1 -, 3 -, 5 - in the octupole vibration band with K=0 -. Some physical problems, such as how to get the optical model parameters of deformed nuclei and phonon amplitudes, are discussed.
基金supported by the National Key Basic Research Program of China(Grant No.2013CB834400)the National Natural Science Foundation of China(Grant Nos.11175252+4 种基金111201010051127524811475115and 11525524)the Knowledge Innovation Project of the Chinese Academy of Sciences(Grant No.KJCX2-EW-N01)
文摘The dynamic coupling effects on fusion cross sections for reactions^(32)S + ^(94,96)Zr and ^(40)Ca + ^(94,96)Zr are studied with the universal fusion function formalism and an empirical coupled channel(ECC) model. An examination of the reduced fusion functions shows that the total effect of couplings to inelastic excitations and neutron transfer channels on fusion in ^(32)S +^(94)Zr(^(40)Ca +^(94)Zr) is almost the same as that in ^(32)S +^(96)Zr(^(40)Ca +^(96)Zr). The enhancements of the fusion cross section at sub-barrier energies due to inelastic channel coupling and neutron transfer channel coupling are evaluated separately by using the ECC model. The results show that effect of couplings to inelastic excitations channels in the reactions with94 Zr as target should be similar as that in the reactions with ^(96) Zr as target. This implies that the quadrupole deformation parameters β_2of ^(94)Zr and^(96) Zr should be similar to each other.However, β_2 's predicted from the finite-range droplet model, which are used in the ECC model, are quite different. Experiments on^(48) Ca +^(94)Zr or^(36) S +^(94)Zr are suggested to solve the puzzling issue concerning β_2for^(94)Zr.
