Generation of endurance time excitation functions using spectral representation method

In this study,application of the spectral representation method for generation of endurance time excitation functions is introduced.Using this method,the intensifying acceleration time series is generated so that its acceleration response spectrum in any desired time duration is compatible with a time-scaled predefined acceleration response spectrum.For this purpose,simulated stationary acceleration time series is multiplied by the time dependent linear modulation function,then using a simple iterative scheme,it is forced to match a target acceleration response spectrum.It is shown that the generated samples have excellent conformity in low frequency,which is useful for nonlinear endurance time analysis.In the second part of this study,it is shown that this procedure can be extended to generate a set of spatially correlated endurance time excitation functions.This makes it possible to assess the performance of long structures under multi-support seismic excitation using endurance time analysis.

Application of Excitation Function to the Prediction of RI Level Caused by Corona Discharge

Radio interference （RI）, as an aftereffect of corona discharge, is an important research topic in the field of electromagnetic compatibility, where excitation function is applied broadly to the prediction of RI level. This paper presents the theory of excitation function method used in the RI level prediction. Then, some practical problems related to this method are discussed. The propagation procedure of corona current is solved by the phase-modal transformation, and the impedance matrix of multi transmission lines is calculated by a double logarithmic approximate model of Carson＇s Ground-Return impedance. At the same time, in order to calculate the RI level when total line corona is assumed, an analytical formula is deduced for integral operation. Based on the above solutions, an algorithm is presented and applied to the prediction of RI level of a practical overhead transmission line. Comparison of prediction and measurement results indicates that the algorithm proposed in this paper is effective and feasible.

Langevin analysis of fission excitation functions induced by protons

The stochastic Langevin approach to fission is applied to analyze fission excitation functions measured in p＋206Pb and p＋209Bi systems. A presaddle friction strength of （3 5） ×1021 s -1 is extracted by comparing theoretical predictions with experimental data. Furthermore, the small distortion of the formed compound nuclei with respect to the spherical shape under the condition of low angular momentum suggests that experimentally, populating an excited compound system via light-ion induced reactions favors a more accurate determination of presaddle friction with a fission cross section.

Cross-section measurements of(n,2n)and(n,p)reactions on ^(124,126,128,130,131,132)Xe in the 14 MeV region and theoretical calculations of their excitation functions

The reaction cross-sections of ^(124)Xe(n,2n)^(123)Xe,^(126)Xe(n,2n)^(125)Xe,^(128)Xe(n,2n)^(127)Xe,^(130)Xe(n,2n)^(129)mXe,^(132)Xe(n,2n)^(131)mXe,^(130)Xe(n,p)^(130)I,^(131)Xe(n,p)^(131)I,and ^(132)Xe(n,p)^(132)I were measured at the 13.5,13.8,14.1,14.4,and 14.8 MeV neutron energies.The monoenergetic neutrons were generated via the ^(3)H(d,n)^(4)He reaction at the China Academy of Engineering Physics using the K-400 Neutron Generator with a solid ^(3)H-Ti target.A high-purity germanium detector was employed to measure the activities of the product.The reactions ^(93)Nb(n,2n)^(92m)Nb and ^(27)Al(n,α)^(24)Na were adopted for neutron flux calibration.The cross sections of the(n,2n)and(n,p)reactions of the xenon isotopes were obtained within the 13-15 MeV neutron energy range.These cross-sections were then compared with the IAEA-exchange format(EXFOR)database-derived experimental data,together with the evaluation results of the CENDL-3,ENDF/B-Ⅷ.0,JENDL-4.0,RUSFOND,and JEFF-3.3 data libraries,as well as the theoretical excitation function obtained using the TALYS-1.95 code.The cross-sections of the reactions(except for the ^(124)Xe(n,2n)^(123)Xe and ^(132)Xe(n,p)^(132)I)at 13.5,13.8,and 14.1 MeV are reported for the first time in this study.The obtained results are beneficial in providing better cross-section constraints for the reactions in the 13-15 MeV region,thus improving the quality of the corresponding database.Meanwhile,these data can also be used for the verification of relevant nuclear reaction model parameters.

The excitation functions of ^(187)Re(n,2n)^(186m,g)Re reactions

A new value for the emission probability of 137.144 keV γ-rays from 186gRe decay is recommended to be （9.47±0.03）/%. Using this value the measured cross sections for 187Re（n,2n）186mRe and 187Re（n,2n）186gRe reactions around 14 MeV are analyzed, and the cross section for187Ke（n,2n）186m＋gRe reaction at 14.g MeV is （2213=k116） mb. The UNF code was adopted to calculate the cross sections for the 187Re（n,2n）186m＋gRe reaction below 20 MeV, fitting to the value （2213±116） mb at 14.8 MeV using a set of optimum neutron optical potential parameters which were obtained based on the relevant experimental data of rhenium. The isomeric cross section ratio for the 187Re（n,2n）186m,gRe reaction was analyzed using the V-H method based on nuclear statistical theory. Combining these calculated results, the excitation functions for the 187Re（n,2n）lS6mRe and 187Re（n,2n）186gRe reactions were obtained. The obtained results are in good agreement with the available experimental data.

Excitation of Annual Polar Motion by the Pacific,Atlantic and Indian Oceans

The global oceans play important roles in exciting the annual polar motion besides the atmosphere. However, it is still unclear about how large the regional oceans contribute to the annual polar motion. We investigate systemically the contributions of the Pacific, Atlantic and Indian Oceans to the excitation of the annual polar motion, based on the output data of ocean current velocity field and ocean bottom pressure field from ＂Estimating the Circulation and Climate of the Ocean （ECCO）＂ ocean circulation model over the period 1993-2005. The result shows that due to its particular location and shape, the Atlantic Ocean makes a less significant contribution to the x-component of the annual polar motion excitation than the Pacific and Indian Oceans, while all these three oceans contribute to the y-component of the annual polar motion excitation to some extent.

Frequency Analysis of Heavy Tamping Vibration

Heavy tamping is one of the important methods for ground treatment. But the vibration is often a problem that restricts the application during heavy tamping. On the other hand, as an instant impact load with controllable energy, heavy tamping is a good test in situ for the study of soil dynamics. With the analysis in the field of frequency, deductive method for medium effecting function and excitation function of heavy tamping is put forward in this paper.

Measurement of the(n,2n)reaction cross-sections of iodine and cesium induced by D-T neutrons with covariance analysis

The cross-sections of the 127I(n,2n)126I and 133Cs(n,2n)132Cs reactions at neutron energies of 13.83±0.05,14.33±0.10,and 14.79±0.10 MeV were measured relative to the 93Nb(n,2n)92mNb reaction using the activation technique in combination with off-lineγ-ray spectrometry.A neutron beam was generated from the T(d,n)4He reaction using the K-400 neutron generator at the China Academy of Engineering Physics.Considering the correlations between different attributes,detailed uncertainty propagation was performed using covariance analysis,and the cross-sections were reported with their uncertainties and correlation matrix.The uncertainty of the measurement cross-sections ranged from 4.84 to 5.90%,which is lower than previous experimental data.Furthermore,the theoretical excitation functions of the 127I(n,2n)126I and 133Cs(n,2n)132Cs reactions were calculated using the TALYS-1.95 and EMPIRE-3.2.3 codes.Then,the experimentally determined cross-sections were analyzed by comparing them with literature data available in the EXFOR database and evaluated nuclear data in the ENDF/B-VIII.0,JEFF-3.3,JENDL-5,BROND-3.1,CENDL-3.2,and TENDL-2021 databases.Compared with the values previously reported in the 13.8-14.8 MeV energy region,the precision of the results obtained in this study was greatly improved.The current experimental results with thorough uncertainties and covariance information are critical for verifying the reliability of the theoretical model and improving the quality of the nuclear database.

Simulation and analysis of ～(13)N+p elastic resonance scattering

The ^13 N＋p elastic resonance scattering has been studied at the secondary radioactive beam facility of CIAE in inverse kinematics via a thick-target method. The excitation function for the ^13N（p,p） scattering was obtained in the energy interval of Ecru ≈0.5-3.2 MeV with a ^13 N secondary beam of （47.8±1.5） MeV. Careful analysis of the secondary beam components and extensive Monte-Carlo simulations enable the resolution of the experimental proton spectra. The resonance parameters for five low-lying levels in ^14 O were deduced by Rmatrix fitting calculations with MULTI7 and SAMMY-M6-BETA. The present results show general agreement with those from a recent similar work, and thus confirm the observation of a new 0^- level at 5.7 MeV in 140 with an improved width of 400（45） keV.

Levels in ^(13)N examined by ^(12)C+p elastic resonancescattering with thick target

The elastic resonance scattering of ^12C＋p has been studied in inverse kinematics via a novel thicktarget method at GIRAFFE facility of HI-13 tandem accelerator laboratory, Beijing. The recoil protons weremeasured by a AE-E counter telescope based on a large area double-sided silicon strip detector at laboratoryangles around θ0 = 15^o. The excitation function for ^12C（p,p） elastic scattering has been obtained over a wideenergy range of Ec.m. =0.31-3.45 MeV, which was explained quite well by the R-matrix calculation with known resonance parameters of the first three levels in ^13N nucleus. Thus it is demonstrated that the present setup can be directly applied to the study of elastic resonance scattering with secondary radioactive beams.

Nuclear data for the cyclotron production of ^(117)Sb and ^(90)Nb

This presented study is to make comparison of cross sections to produce 117Sb and 90Nb via different reactions with particle incident energy up to 70 MeV as a part of systematic studies on particle-induced activations on enriched Sn, Y2O3 and ZrO2 targets, theoretical calculation of production yield, calculation of required thickness of target and suggestion of optimum reaction to produce Antimony-117 and Niobium-90.

Relationship between polar motion and key hydrological elements at multiple scales

Changes in the elements of the Earth system are closely related.Finding the key factors linked with hydrological changes is significant for in-depth analysis of hydrological changes.This study chooses polar motion,which is the movement of the Earth’s rotational axis relative to its crust,as a key factor in the investigation of the physical processes of its interaction with several hydrological elements.First,the statistical relationships between polar motion and multi-hydrological elements(i.e.,precipitation,evaporation,runoff,and terrestrial water storage)are investigated,using trend analysis,mutation analysis,cycle analysis,and correlation analysis methods,from basinal to global and from intra-annual to inter-annual scales.Second,their interactions are explored.The study quantifies the effect of hydrological changes on polar motion using the excitation function.It explores the effect of polar motion on hydrological changes based on the theory of equilibrium tides and atmospheric dynamics.The results show that they are significantly correlated and abruptly changed at a similar time.First,regional to global hydrological changes can significantly excite polar motion.From April 2002 to June 2020,the global terrestrial water storage decreased significantly(by approximately−4.68 mm yr^(−1)),which significantly drove polar motion towards the direction of the Greenwich Meridian(by approximately 4.32 mas yr^(−1)).Changes in regional terrestrial water storage also contributed significantly to directional changes in polar motion around 2005 and 2012.Second,polar motion can perturb the Earth’s centrifugal force system and generate equilibrium tides,and thus further cause changes in sea-level pressure,wind,and water vapor transport.Results show that polar motion-induced water vapor flux divergences correlate significantly with actual precipitation and terrestrial water storage changes in the Yangtze River and the Pearl River basins.Their correlations are also significant when trends are removed,and the polar motion-induced changes are 4 to 14 months earlier.This study further demonstrates the relationship between polar motion and hydrological changes and helps to understand the related factors of hydrological changes in other Earth systems.

Cross-sections for(n,2n),(n,α),(n,p),(n,d),and(n,t)reactions on molybdenum isotopes in the neutron energy range of 13 to 15 MeV

Given the insufficient cross-sectional data regarding the 14-MeV-neutron experiment of molybdenum,the vital fusion reactor structural material,and the significant heterogeneities among the reported values,this study examined the(n,2n),(n,α),(n,p),(n,d),and(n,t)reaction cross sections in molybdenum isotopes based on the neutrons produced via a T(d,n)4He reaction carried out in the Pd-300 Neutron Generator at the China Academy of Engineering Physics(CAEP).A high-resolution gamma-ray spectrometer,which was equipped with a coaxial high-purity germanium detector,was used to measure the product nuclear gamma activities.In addition,27Al(n,α)24Na and 93Nb(n,2n)92mNb reactions were utilized as the neutron fluence standards.The experimental 92Mo(n,2n)91Mo,94Mo(n,2n)93mMo,100Mo(n,2n)99Mo,98Mo(n,α)95Zr,100Mo(n,α)97Zr,92Mo(n,p)92mNb,96Mo(n,p)96Nb,97Mo(n,p)97Nb,98Mo(n,p)98mNb,92Mo(n,d)91mNb,and 92Mo(n,t)90Nb reaction cross sections were acquired within the 13-15 MeV neutron energy range.Thereafter,we compared and analyzed these obtained cross sections based on the existing IAEA-EXFOR database-derived experimental data,together with evaluation results corresponding to ENDF/B-Ⅷ.0,JEFF-3.3,BROND-3.1,and CENDL-3.1 and the theoretical outcomes acquired through TALYS-1.95 and EMPIRE-3.2.3(nuclear-reaction modeling tools).