Using the constitutive equation of co-rotational derivative type for anisotropic viscoelastic fluid-liquid crystalline(LC),polymer liquids was developed.Two relaxation times are introduced in the equation:λn represen...Using the constitutive equation of co-rotational derivative type for anisotropic viscoelastic fluid-liquid crystalline(LC),polymer liquids was developed.Two relaxation times are introduced in the equation:λn represents relaxation of the normal-symmetric stress components;λs represents relaxation of the shear-unsymmetric stress components.A vibrational rotating flow in gap between cylinders with small amplitudes is studied for the anisotropic viscoelastic fluid-liquid crystalline polymer.The time-dependent constitutive equation are linearized with respect to parameter of small amplitude.For the normal-symmetric part of stress tensor analytical expression of the shear stress is obtained by the constitutive equation.The complex viscosity,complex shear modulus,dynamic and imaginary viscosities,storage modulus and loss modulus are obtained for the normal-symmetric stress case which are defined by the common shear rate.For the shear-unsymmetric stress part,two shear stresses are obtained thus two complex viscosities and two complex shear modulus(i.e.first and second one) are given by the constitutive equation which are defined by rotating shear rate introduced by author.The dynamic and imaginary viscosities,storage modulus and loss modulus are given for each complex viscosities and complex shear modulus.Using the constituive equation the rotating flow with small amplitudes in gap between two coaxial cylinders is studied.展开更多
To enhance the optimization ability of particle swarm algorithm, a novel quantum-inspired particle swarm optimization algorithm is proposed. In this method, the particles are encoded by the probability amplitudes of t...To enhance the optimization ability of particle swarm algorithm, a novel quantum-inspired particle swarm optimization algorithm is proposed. In this method, the particles are encoded by the probability amplitudes of the basic states of the multi-qubits system. The rotation angles of multi-qubits are determined based on the local optimum particle and the global optimal particle, and the multi-qubits rotation gates are employed to update the particles. At each of iteration, updating any qubit can lead to updating all probability amplitudes of the corresponding particle. The experimental results of some benchmark functions optimization show that, although its single step iteration consumes long time, the optimization ability of the proposed method is significantly higher than other similar algorithms.展开更多
An improved measurement method of circularly-polarized (CP) antennas based on linear-component amplitudes is proposed in this paper. By utilizing two sets of orthogonal linear polarization (LP) amplitudes, measurement...An improved measurement method of circularly-polarized (CP) antennas based on linear-component amplitudes is proposed in this paper. By utilizing two sets of orthogonal linear polarization (LP) amplitudes, measurement on axial ratio (AR) of CP antennas can be realized without phase information. However, the rotation sense of the co-polarization cannot be determined due to the absence of the phase information. Above problem is discussed here for the first time, and a solution is presented to determine the rotation sense of the co-polarization by using common auxiliary CP antennas. In addition, there will be some particular cases with large errors in actual measurement. Here a corresponding solution method is given. Finally, co-polarization and cross-polarization patterns can be further obtained from AR results. To verify this improved method, a self-developed CP microstrip array was measured. The measured results are in agreement with the simulated results, which prove this method is correct, effective and practical.展开更多
Low cycle fatigue behavior of extruded AZ80 magnesium alloy was investigated under uniaxial tension-compression at different strain amplitudes and strain rates.The results show that the extruded AZ80 magnesium alloy e...Low cycle fatigue behavior of extruded AZ80 magnesium alloy was investigated under uniaxial tension-compression at different strain amplitudes and strain rates.The results show that the extruded AZ80 magnesium alloy exhibits cyclic hardening at strain amplitudes ranging from 0.4%to 1.0%,the asymmetry of hysteresis loops becomes increasingly obvious when the strain amplitude increases.Higher strain rates correspond to higher stress amplitudes,high mean stresses and short fatigue life.{10–12}extension twins play a role in the cyclic deformation under higher strain amplitudes(0.8%,1.0%).The relationship between total strain energy density and fatigue life can be described by the modified Morrow model.The effect of strain rate on the fatigue life can also be predicted by the model.展开更多
The variations in the wave energy and the amplitude along the energy dispersion paths of the barotropic Rossby waves in zonally symmetric basic flow are studied by solving the wave energy equation,which expresses that...The variations in the wave energy and the amplitude along the energy dispersion paths of the barotropic Rossby waves in zonally symmetric basic flow are studied by solving the wave energy equation,which expresses that the wave energy variability is determined by the divergence of the group velocity and the energy budget from the basic flow.The results suggest that both the wave energy and the amplitude of a leading wave increase significantly in the propagating region that is located south of the jet axis and enclosed by a southern critical line and a northern turning latitude.The leading wave gains the barotropic energy from the basic flow by eddy activities.The amplitude continuously climbs up a peak at the turning latitude due to increasing wave energy and enlarging horizontal scale(shrinking total wavenumber).Both the wave energy and the amplitude eventually decrease when the trailing wave continuously approaches southward to the critical line.The trailing wave decays and its energy is continuously absorbed by the basic flow.Furthermore,both the wave energy and the amplitude oscillate with a limited range in the propagating region that is located near the jet axis and enclosed by two turning latitudes.Both the leading and trailing waves neither develop nor decay significantly.The jet works as a waveguide to allow the waves to propagate a long distance.展开更多
The dynamic frictional behaviors of natural discontinuities(joints,fractures,faults)play an important role in geohazards assessment;however,the mechanisms of the dynamic fault weakening/strengthening are still unclear...The dynamic frictional behaviors of natural discontinuities(joints,fractures,faults)play an important role in geohazards assessment;however,the mechanisms of the dynamic fault weakening/strengthening are still unclear.In this paper,a dynamic shear box was used to perform direct shear tests on saw-cut(planar)and natural(rough)granite fractures,with different normal load oscillation amplitudes.Based on the recorded shear forces and normal displacements,the shear forces,apparent friction coefficients and normal displacements are found to change periodically with oscillated normal loads and are characterized by a series of time shifts.The observed changing patterns are similar for the rough and planar fractures.Compared with the test data under constant normal load(CNL),small/large normal load oscillation amplitude enhances/reduces the peak shear strength,with a critical point.The magnitude of critical normal load oscillation for the rough fractures is smaller than the planer fractures.The results imply that dynamic fault weakening/strengthening can be achieved by both normal load oscillation amplitudes and slip surface topography.The rough fractures with larger normal oscillation amplitude can easily cause frictional weakening under stress disturbance.展开更多
Although some short-term follow-up studies have found that individuals recovering from coronavirus disease 2019(COVID-19)exhibit anxiety,depression,and altered brain microstructure,their long-term physical problems,ne...Although some short-term follow-up studies have found that individuals recovering from coronavirus disease 2019(COVID-19)exhibit anxiety,depression,and altered brain microstructure,their long-term physical problems,neuropsychiatric sequelae,and changes in brain function remain unknown.This observational cohort study collected 1-year follow-up data from 22 patients who had been hospitalized with COVID-19(8 males and 11 females,aged 54.2±8.7 years).Fatigue and myalgia were persistent symptoms at the 1-year follow-up.The resting state functional magnetic resonance imaging revealed that compared with 29 healthy controls(7 males and 18 females,aged 50.5±11.6 years),COVID-19 survivors had greatly increased amplitude of low-frequency fluctuation(ALFF)values in the left precentral gyrus,middle frontal gyrus,inferior frontal gyrus of operculum,inferior frontal gyrus of triangle,insula,hippocampus,parahippocampal gyrus,fusiform gyrus,postcentral gyrus,inferior parietal angular gyrus,supramarginal gyrus,angular gyrus,thalamus,middle temporal gyrus,inferior temporal gyrus,caudate,and putamen.ALFF values in the left caudate of the COVID-19 survivors were positively correlated with their Athens Insomnia Scale scores,and those in the left precentral gyrus were positively correlated with neutrophil count during hospitalization.The long-term follow-up results suggest that the ALFF in brain regions related to mood and sleep regulation were altered in COVID-19 survivors.This can help us understand the neurobiological mechanisms of COVID-19-related neuropsychiatric sequelae.This study was approved by the Ethics Committee of the Second Xiangya Hospital of Central South University(approval No.2020 S004)on March 19,2020.展开更多
Variations in wave energy and amplitude for Rossby waves are investigated by solving the wave energy equation for the quasigeostrophic barotropic potential vorticity model.The results suggest that compared with rays i...Variations in wave energy and amplitude for Rossby waves are investigated by solving the wave energy equation for the quasigeostrophic barotropic potential vorticity model.The results suggest that compared with rays in the nondivergent barotropic model,rays in the divergent model can have enhanced meridional and zonal propagation,accompanied by a more dramatic variability in both wave energy and amplitude,which is caused by introducing the divergence effect of the free surface in the quasigeostrophic model.For rays propagating in a region enclosed by a turning latitude and a critical latitude,the wave energy approaches the maximum value inside the region,while the amplitude approaches the maximum at the turning latitude.Waves can develop when both the wave energy and amplitude increase.For rays propagating in a region enclosed by two turning latitudes,the wave energy approaches the minimum value at one turning latitude and the maximum value at the other latitude,while the total wavenumber approaches the maximum value inside the region.The resulting amplitude increases if the total wavenumber decreases or the wave energy increases more significantly and decreases if the total wavenumber increases or the wave energy decreases more significantly.The matched roles of the energy from the basic flow and the divergence of the group velocity contribute to the slightly oscillating wave energy,which causes a slightly oscillating amplitude as well as the slightly oscillating total wavenumber.展开更多
Approaching the distance of 180°, seismic focusing greatly amplifies the normally weak PKIIKP phase(underside reflection from the inner core boundary). Anomalously strong amplitudes of the PKIIKP phase reported p...Approaching the distance of 180°, seismic focusing greatly amplifies the normally weak PKIIKP phase(underside reflection from the inner core boundary). Anomalously strong amplitudes of the PKIIKP phase reported previously at near antipodal distances(at seismic station TAM in North Africa) have been interpreted to infer anomalous structure(s) of the inner core boundary(including a sharp drop of compressional wave speed in the bottommost outer core or a near-zero shear wave speed in the topmost inner core). However,our observations of 12 earthquakes located antipodal to TAM(including the previously cited four events) suggest, for several reasons,that the anomalous PKIIKP energy might be a seismic phase misidentification. The anomalous phase appeared at distances less than 179.6° but not at larger distances(~179.8°). The phase appears consistently from antipode to distances less than 160° and has horizontal slowness similar to the PKIKP phase(going straight through the inner core). Its travel times vary greatly and show a systematic difference between two groups of events at different distances. A simple point scatter provides a good match to the travel times and the systematic variation of the anomalous phase at most stations, suggesting that it could originate from scattering off strong heterogeneities in the mantle wedge above the subducting Tonga slab. The phase misidentification suggests that the previously proposed inner core boundary structure(s) based on the anomalous phase need to be re-evaluated.展开更多
A linear model of three layers plane wall exposed to oscillating temperatures with different amplitudes and frequencies was built by using a physical superposition. A physical superposition of two states was performed...A linear model of three layers plane wall exposed to oscillating temperatures with different amplitudes and frequencies was built by using a physical superposition. A physical superposition of two states was performed, one state is a wall which one surface is exposed to oscillating temperature and the other surface is exposed to zero relative temperature and a second state is a wall which one surface is exposed to relative zero temperature while the other surface is exposed to oscillating temperature with different amplitudes and frequencies. Temperature distributions were introduced for different amplitudes, frequencies and thermal conductivities. It was shown that increasing the frequency value decreases the temperature penetration length, high frequency value leads to extremum temperature values changes on the surface while low frequency value allows gradually temperature changes during the time period. Temperature distribution lines where there are at the same time heat flux entry and heat flux exit were not received for the same constraint frequencies.展开更多
We present a general method of constructing unfactorizable on-shell amplitudes(amplitude basis) and build up their one-to-one correspondence to the independent and complete operator basis in effective field theory(EFT...We present a general method of constructing unfactorizable on-shell amplitudes(amplitude basis) and build up their one-to-one correspondence to the independent and complete operator basis in effective field theory(EFT).We apply our method to the Standard Model EFT and identify the amplitude basis in dimensions 5 and 6,which correspond to the Weinberg operator and operators in the Warsaw basis,except for some linear combinations.展开更多
Light-cone distribution amplitudes(LCDAs)are essential nonperturbative quantities for theoretical predictions of exclusive highenergy processes in quantum chromodynamics(QCD).We demonstrate the prospect of calculating...Light-cone distribution amplitudes(LCDAs)are essential nonperturbative quantities for theoretical predictions of exclusive highenergy processes in quantum chromodynamics(QCD).We demonstrate the prospect of calculating LCDAs on a quantum computer by applying a recently proposed quantum algorithm,with staggered fermions,to the simulation of the LCDA in the(1+1)-dimensional Nambu-Jona-Lasinio(NJL)model on classical hardware.The agreement between the result from the classical simulation of the quantum algorithm and that from exact diagonalization justifies the proposed quantum algorithm.We find that the resulting LCDA in the NJL model exhibits features shared with the LCDAs obtained from the QCD.展开更多
CP violation may play an important role in baryogenesis in the early universe and should be examined comprehensively at colliders.We study the CP properties of HVV vertexes between Higgs and gauge boson pairs by defin...CP violation may play an important role in baryogenesis in the early universe and should be examined comprehensively at colliders.We study the CP properties of HVV vertexes between Higgs and gauge boson pairs by defining a CP violation phase angle,which indicates the mixture of CP-even and CP-odd Higgs states in HVV in new physics.A series of HVV amplitudes,H→γγ,H-→V→γtt,and H→VV-→4f,with a CP phase angle are studied systematically to explicitly explain why CP violation can only be probed independently in the 4t pro-cess.We obtain a novel amplitude decomposition relation that illustrates that if two preconditions(multilinear mo-mentum dependent vertexes,and the current J_(μ) of V→l^(+)l^(-)is formally proportional to a photon's polarization vec-tor)are satisfied,a higher-point amplitude can be decomposed into a summation of a series of lower-point amp-litudes.As a practical example,the amplitude of the H→γV-→γtt and H→VV→4t processes can be decom-posed into a summation of many H→γγ amplitudes.We calculate these amplitudes in the framework of the on-shell scattering amplitude method,considering both massless and massive vector gauge bosons with the CP viola-tion phase angle.The above two approaches provide consistent results and clearly reveal the CP violation ξ depend-ence in the amplitudes.展开更多
Owing to the significant difference between the experimental measurements and the theoretical predictions of the standard model(SM)for the value of R(D)of the semileptonic decay B→Dtve,researchers speculate that this...Owing to the significant difference between the experimental measurements and the theoretical predictions of the standard model(SM)for the value of R(D)of the semileptonic decay B→Dtve,researchers speculate that this decay may be evidence of new physics beyond the SM.Usually,the D-meson twist-2,3 distribution amplitudes(DAs)Φ2;D(x,μ),d3:D(x,μ),and$g:D(x,μ)are the main error sources when perturbative QCD factorization and light-cone QCD sum rules are used to study B→Dtve.Therefore,it is important to obtain more reasonable and accurate behaviors for these DAs.Motivated by our previous work[Phys.Rev.D 104,no.1,016021(2021)]on pionic leading-twist DA,we revisit D-meson twist-2,3 DAsΦ2:D(x,μ),Φp3:D(x,μ),andΦσ3:D(x,μ).New sum rule formulae for the-moments of these three DAs are suggested for obtaining more accurate values.The light-cone harmonic oscillator models for the DAs are improved,and their parameters are determined by fitting the values of-moments via the least squares method.展开更多
Motivated by the problem of expanding the single-trace tree-level amplitude of Einstein-Yang-Mills theory to the BCJ basis of Yang-Mills amplitudes,we present an alternative expansion formula in gauge invariant vector...Motivated by the problem of expanding the single-trace tree-level amplitude of Einstein-Yang-Mills theory to the BCJ basis of Yang-Mills amplitudes,we present an alternative expansion formula in gauge invariant vector space.Starting from a generic vector space consisting of polynomials of momenta and polarization vectors,we define a new sub-space as a gauge invariant vector space by imposing constraints on the gauge invariant conditions.To characterize this sub-space,we compute its dimension and construct an explicit gauge invariant basis from it.We propose an expansion formula in this gauge invariant basis with expansion coefficients being linear combinations of the Yang-Mills amplitude,manifesting the gauge invariance of both the expansion basis and coefficients.With the help of quivers,we compute the expansion coefficients via differential operators and demonstrate the general expansion algorithm using several examples.展开更多
New techniques for controlling the amplitudes of two orthogonal linearly polarized light are presented. One is based on adjusting the DC voltage into a Mach–Zehnder modulator(MZM) to alter the amplitude of the ligh...New techniques for controlling the amplitudes of two orthogonal linearly polarized light are presented. One is based on adjusting the DC voltage into a Mach–Zehnder modulator(MZM) to alter the amplitude of the light traveling on the slow axis of a fiber into the modulator with little changes in the fast-axis light amplitude.Another is based on adjusting the input DC voltages of a dual-polarization MZM operating in the reverse direction, which enables independent control of the two input orthogonal linearly polarized light amplitudes.Experimental results demonstrate that more than 30 dB difference in slow-and fast-axis light power can be obtained by controlling an MZM input DC voltage, and over 24 dB independent power adjustment for light traveling on the slow and fast axes into a dual-polarization MZM.展开更多
We have theoretically and experimentally studied the dispersive signal of the Rydberg atomic electromagneticallyinduced transparency(EIT)Autler–Townes(AT)splitting spectra obtained using amplitude modulation of the m...We have theoretically and experimentally studied the dispersive signal of the Rydberg atomic electromagneticallyinduced transparency(EIT)Autler–Townes(AT)splitting spectra obtained using amplitude modulation of the microwave(MW)electric field.In addition to the two zero-crossing points interval△f_(zeros),the dispersion signal has two positive maxima with an interval defined as the shoulder interval△f_(sho),which is theoretically expected to be used to measure a much weaker MW electric field.The relationship of the MW field strength E_(MW)and△f_(sho)is experimentally studied at the MW frequencies of 31.6 GHz and 9.2 GHz respectively.The results show that△f_(sho)can be used to characterize the much weaker E_(MW)than that of△f_(zeros)and the traditional EIT–AT splitting interval△f_(m);the minimum E_(MW)measured by△f_(sho)is about 30 times smaller than that by△f_(m).As an example,the minimum E_(MW)at 9.2 GHz that can be characterized by△f_(sho)is 0.056 mV/cm,which is the minimum value characterized by the frequency interval using a vapor cell without adding any auxiliary fields.The proposed method can improve the weak limit and sensitivity of E_(MW)measured by the spectral frequency interval,which is important in the direct measurement of weak E_(MW).展开更多
In order to forecast the distribution of crest amplitudes and the occurrence of freak waves in a short crested coastal sea,a novel transformed linear simulation method is initially proposed in this paper.A Hermite tra...In order to forecast the distribution of crest amplitudes and the occurrence of freak waves in a short crested coastal sea,a novel transformed linear simulation method is initially proposed in this paper.A Hermite transformation model expressed as a monotonic cubic polynomial serves as the foundation for the novel simulation technique.The wave crest amplitude exceedance probabilities of two sea states-one with a directional wave spectrum based on the measured wave elevation data at the Yura coast and the other with a typical directional JONSWAP wave spectrum-have been predicted using the novel simulation method that has been proposed.The likelihood that a particular critical wave crest amplitude will be exceeded is directly correlated with the probability that freak waves will occur.It is shown that the novel simulation approach suggested can provide predictions that are more precise than those obtained from the Rayleigh crest amplitude distribution model,the Jahns and Wheeler crest amplitude distribution model,or the conventional linear simulation method.This study also demonstrated that the nonlinear simulation method is less effective than the novel simulation method in terms of efficiency.展开更多
Cold Metal Transfer-Based Wire Arc Directed Energy Deposition(CMT-WA-DED)presents a promising avenue for the rapid fabrication of components crucial to automotive,shipbuilding,and aerospace industries.However,the susc...Cold Metal Transfer-Based Wire Arc Directed Energy Deposition(CMT-WA-DED)presents a promising avenue for the rapid fabrication of components crucial to automotive,shipbuilding,and aerospace industries.However,the susceptibility to fatigue of CMT-WA-DED-produced AZ31 Mg alloy components has impeded their widespread adoption for critical load-bearing applications.In this study,a comprehensive investigation into the fatigue behaviour of WA-DED-fabricated AZ31 Mg alloy has been carried out and compared to commercially available wrought AZ31 alloy.Our findings indicate that the as-deposited parts exhibit a lower fatigue life than wrought Mg alloy,primarily due to poor surface finish,tensile residual stress,porosity,and coarse grain microstructure inherent in the WA-DED process.Low Plasticity Burnishing(LPB)treatment is applied to mitigate these issues,which induce significant plastic deformation on the surface.This treatment resulted in a remarkable improvement of fatigue life by 42%,accompanied by a reduction in surface roughness,grain refinement and enhancement of compressive residual stress levels.Furthermore,during cyclic deformation,WA-DED specimens exhibited higher plasticity and dislocation density compared to both wrought and WA-DED+LPB specimens.A higher fraction of Low Angle Grain Boundaries(LAGBs)in WA-DED specimens contributed to multiple crack initiation sites and convoluted crack paths,ultimately leading to premature failure.In contrast,wrought and WA-DED+LPB specimens displayed a higher percentage of High Angle Grain Boundaries(HAGBs),which hindered dislocation movement and resulted in fewer crack initiation sites and less complex crack paths,thereby extending fatigue life.These findings underscore the effectiveness of LPB as a post-processing technique to enhance the fatigue performance of WA-DED-fabricated AZ31 Mg alloy components.Our study highlights the importance of LPB surface treatment on AZ31 Mg components produced by CMT-WA-DED to remove surface defects,enabling their widespread use in load-bearing applications.展开更多
In order to reduce the intrinsic interference of the filter bank multicarrier-quadrature amplitude modulation(FBMC-QAM)system,a novel filter optimization scheme based on discrete prolate spheroidal sequences(DPSS)is p...In order to reduce the intrinsic interference of the filter bank multicarrier-quadrature amplitude modulation(FBMC-QAM)system,a novel filter optimization scheme based on discrete prolate spheroidal sequences(DPSS)is proposed.Firstly,a prototype filter function based on DPSS is designed,since the eigenvalue can be used as an indicator of the energy concentration of DPSS,so a threshold is set,and the sequence with the most concentrated energy is selected under the threshold,that is,the sequence with the eigenvalue higher than the threshold,and the prototype filter function is rewritten as a weighted sum function of multiple eigenvectors.Under the energy constraints of the filter,the relationship between the eigenvectors and the intrinsic interference function is established,and the function problem is transformed into an optimization problem for the weighted coefficients.Through the interior point method,the most suitable weight is found to obtain the minimum intrinsic interference result.Theoretical analysis and simulation results show that compared with the prototype filters such as Type1 and CaseC,the DPSS filter applying the proposed optimization algorithm can effectively suppress the intrinsic interference of the system and obtain a better bit error rate(BER)performance.展开更多
基金Project(10772177) supported by the National Natural Science Foundation of China
文摘Using the constitutive equation of co-rotational derivative type for anisotropic viscoelastic fluid-liquid crystalline(LC),polymer liquids was developed.Two relaxation times are introduced in the equation:λn represents relaxation of the normal-symmetric stress components;λs represents relaxation of the shear-unsymmetric stress components.A vibrational rotating flow in gap between cylinders with small amplitudes is studied for the anisotropic viscoelastic fluid-liquid crystalline polymer.The time-dependent constitutive equation are linearized with respect to parameter of small amplitude.For the normal-symmetric part of stress tensor analytical expression of the shear stress is obtained by the constitutive equation.The complex viscosity,complex shear modulus,dynamic and imaginary viscosities,storage modulus and loss modulus are obtained for the normal-symmetric stress case which are defined by the common shear rate.For the shear-unsymmetric stress part,two shear stresses are obtained thus two complex viscosities and two complex shear modulus(i.e.first and second one) are given by the constitutive equation which are defined by rotating shear rate introduced by author.The dynamic and imaginary viscosities,storage modulus and loss modulus are given for each complex viscosities and complex shear modulus.Using the constituive equation the rotating flow with small amplitudes in gap between two coaxial cylinders is studied.
文摘To enhance the optimization ability of particle swarm algorithm, a novel quantum-inspired particle swarm optimization algorithm is proposed. In this method, the particles are encoded by the probability amplitudes of the basic states of the multi-qubits system. The rotation angles of multi-qubits are determined based on the local optimum particle and the global optimal particle, and the multi-qubits rotation gates are employed to update the particles. At each of iteration, updating any qubit can lead to updating all probability amplitudes of the corresponding particle. The experimental results of some benchmark functions optimization show that, although its single step iteration consumes long time, the optimization ability of the proposed method is significantly higher than other similar algorithms.
文摘An improved measurement method of circularly-polarized (CP) antennas based on linear-component amplitudes is proposed in this paper. By utilizing two sets of orthogonal linear polarization (LP) amplitudes, measurement on axial ratio (AR) of CP antennas can be realized without phase information. However, the rotation sense of the co-polarization cannot be determined due to the absence of the phase information. Above problem is discussed here for the first time, and a solution is presented to determine the rotation sense of the co-polarization by using common auxiliary CP antennas. In addition, there will be some particular cases with large errors in actual measurement. Here a corresponding solution method is given. Finally, co-polarization and cross-polarization patterns can be further obtained from AR results. To verify this improved method, a self-developed CP microstrip array was measured. The measured results are in agreement with the simulated results, which prove this method is correct, effective and practical.
基金the National Basic Research Program of China(No.2013CB632205).
文摘Low cycle fatigue behavior of extruded AZ80 magnesium alloy was investigated under uniaxial tension-compression at different strain amplitudes and strain rates.The results show that the extruded AZ80 magnesium alloy exhibits cyclic hardening at strain amplitudes ranging from 0.4%to 1.0%,the asymmetry of hysteresis loops becomes increasingly obvious when the strain amplitude increases.Higher strain rates correspond to higher stress amplitudes,high mean stresses and short fatigue life.{10–12}extension twins play a role in the cyclic deformation under higher strain amplitudes(0.8%,1.0%).The relationship between total strain energy density and fatigue life can be described by the modified Morrow model.The effect of strain rate on the fatigue life can also be predicted by the model.
基金This study was jointly funded by the National Natural Science Foundation of China(Grant Nos.41505042 and 41805041)the National Program on Global Change and Air−Sea Interaction(Grant No.GASI-IPOVAI-03)+1 种基金the National Basic Research Program of China(Grant Nos.2015CB953601 and 2014CB953903)the Fundamental Research Funds for the Central Universities.
文摘The variations in the wave energy and the amplitude along the energy dispersion paths of the barotropic Rossby waves in zonally symmetric basic flow are studied by solving the wave energy equation,which expresses that the wave energy variability is determined by the divergence of the group velocity and the energy budget from the basic flow.The results suggest that both the wave energy and the amplitude of a leading wave increase significantly in the propagating region that is located south of the jet axis and enclosed by a southern critical line and a northern turning latitude.The leading wave gains the barotropic energy from the basic flow by eddy activities.The amplitude continuously climbs up a peak at the turning latitude due to increasing wave energy and enlarging horizontal scale(shrinking total wavenumber).Both the wave energy and the amplitude eventually decrease when the trailing wave continuously approaches southward to the critical line.The trailing wave decays and its energy is continuously absorbed by the basic flow.Furthermore,both the wave energy and the amplitude oscillate with a limited range in the propagating region that is located near the jet axis and enclosed by two turning latitudes.Both the leading and trailing waves neither develop nor decay significantly.The jet works as a waveguide to allow the waves to propagate a long distance.
基金the funding support from the National Natural Science Foundation of China (Grant No. 51904359)the Guangdong Provincial Department of Science and Technology (Grant No. 2019ZT08G090)the Open Research Fund of the State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology (CUMT) (Grant No. SKLCRSM20KF002)
文摘The dynamic frictional behaviors of natural discontinuities(joints,fractures,faults)play an important role in geohazards assessment;however,the mechanisms of the dynamic fault weakening/strengthening are still unclear.In this paper,a dynamic shear box was used to perform direct shear tests on saw-cut(planar)and natural(rough)granite fractures,with different normal load oscillation amplitudes.Based on the recorded shear forces and normal displacements,the shear forces,apparent friction coefficients and normal displacements are found to change periodically with oscillated normal loads and are characterized by a series of time shifts.The observed changing patterns are similar for the rough and planar fractures.Compared with the test data under constant normal load(CNL),small/large normal load oscillation amplitude enhances/reduces the peak shear strength,with a critical point.The magnitude of critical normal load oscillation for the rough fractures is smaller than the planer fractures.The results imply that dynamic fault weakening/strengthening can be achieved by both normal load oscillation amplitudes and slip surface topography.The rough fractures with larger normal oscillation amplitude can easily cause frictional weakening under stress disturbance.
基金supported by Key Emergency Project of Pneumonia Epidemic of Novel Coronavirus Infection of China,No.2020SK3006(to JL)Clinical Research Center for Medical Imaging in Hunan Province of China,No.2020SK4001(to JL)the Innovative Major Emergency Project Funding against the New Coronavirus Pneumonia in Hunan Province of China,No.2020SK3014(to JYL)。
文摘Although some short-term follow-up studies have found that individuals recovering from coronavirus disease 2019(COVID-19)exhibit anxiety,depression,and altered brain microstructure,their long-term physical problems,neuropsychiatric sequelae,and changes in brain function remain unknown.This observational cohort study collected 1-year follow-up data from 22 patients who had been hospitalized with COVID-19(8 males and 11 females,aged 54.2±8.7 years).Fatigue and myalgia were persistent symptoms at the 1-year follow-up.The resting state functional magnetic resonance imaging revealed that compared with 29 healthy controls(7 males and 18 females,aged 50.5±11.6 years),COVID-19 survivors had greatly increased amplitude of low-frequency fluctuation(ALFF)values in the left precentral gyrus,middle frontal gyrus,inferior frontal gyrus of operculum,inferior frontal gyrus of triangle,insula,hippocampus,parahippocampal gyrus,fusiform gyrus,postcentral gyrus,inferior parietal angular gyrus,supramarginal gyrus,angular gyrus,thalamus,middle temporal gyrus,inferior temporal gyrus,caudate,and putamen.ALFF values in the left caudate of the COVID-19 survivors were positively correlated with their Athens Insomnia Scale scores,and those in the left precentral gyrus were positively correlated with neutrophil count during hospitalization.The long-term follow-up results suggest that the ALFF in brain regions related to mood and sleep regulation were altered in COVID-19 survivors.This can help us understand the neurobiological mechanisms of COVID-19-related neuropsychiatric sequelae.This study was approved by the Ethics Committee of the Second Xiangya Hospital of Central South University(approval No.2020 S004)on March 19,2020.
基金This study was jointly funded by the National Natural Science Foundation of China(Grant Nos.41805041 and 41505042)the National Program on Global Change and Air-Sea Interaction(GASI-IPOVAI-03)+1 种基金the National Basis Research Program of China(2015CB953601 and 2014CB953903)the Fundamental Research Funds for the Central Universities.
文摘Variations in wave energy and amplitude for Rossby waves are investigated by solving the wave energy equation for the quasigeostrophic barotropic potential vorticity model.The results suggest that compared with rays in the nondivergent barotropic model,rays in the divergent model can have enhanced meridional and zonal propagation,accompanied by a more dramatic variability in both wave energy and amplitude,which is caused by introducing the divergence effect of the free surface in the quasigeostrophic model.For rays propagating in a region enclosed by a turning latitude and a critical latitude,the wave energy approaches the maximum value inside the region,while the amplitude approaches the maximum at the turning latitude.Waves can develop when both the wave energy and amplitude increase.For rays propagating in a region enclosed by two turning latitudes,the wave energy approaches the minimum value at one turning latitude and the maximum value at the other latitude,while the total wavenumber approaches the maximum value inside the region.The resulting amplitude increases if the total wavenumber decreases or the wave energy increases more significantly and decreases if the total wavenumber increases or the wave energy decreases more significantly.The matched roles of the energy from the basic flow and the divergence of the group velocity contribute to the slightly oscillating wave energy,which causes a slightly oscillating amplitude as well as the slightly oscillating total wavenumber.
基金supported by National Science Foundation of China(41774056)the US Nationa Science Foundation(EAR 1620595)
文摘Approaching the distance of 180°, seismic focusing greatly amplifies the normally weak PKIIKP phase(underside reflection from the inner core boundary). Anomalously strong amplitudes of the PKIIKP phase reported previously at near antipodal distances(at seismic station TAM in North Africa) have been interpreted to infer anomalous structure(s) of the inner core boundary(including a sharp drop of compressional wave speed in the bottommost outer core or a near-zero shear wave speed in the topmost inner core). However,our observations of 12 earthquakes located antipodal to TAM(including the previously cited four events) suggest, for several reasons,that the anomalous PKIIKP energy might be a seismic phase misidentification. The anomalous phase appeared at distances less than 179.6° but not at larger distances(~179.8°). The phase appears consistently from antipode to distances less than 160° and has horizontal slowness similar to the PKIKP phase(going straight through the inner core). Its travel times vary greatly and show a systematic difference between two groups of events at different distances. A simple point scatter provides a good match to the travel times and the systematic variation of the anomalous phase at most stations, suggesting that it could originate from scattering off strong heterogeneities in the mantle wedge above the subducting Tonga slab. The phase misidentification suggests that the previously proposed inner core boundary structure(s) based on the anomalous phase need to be re-evaluated.
文摘A linear model of three layers plane wall exposed to oscillating temperatures with different amplitudes and frequencies was built by using a physical superposition. A physical superposition of two states was performed, one state is a wall which one surface is exposed to oscillating temperature and the other surface is exposed to zero relative temperature and a second state is a wall which one surface is exposed to relative zero temperature while the other surface is exposed to oscillating temperature with different amplitudes and frequencies. Temperature distributions were introduced for different amplitudes, frequencies and thermal conductivities. It was shown that increasing the frequency value decreases the temperature penetration length, high frequency value leads to extremum temperature values changes on the surface while low frequency value allows gradually temperature changes during the time period. Temperature distribution lines where there are at the same time heat flux entry and heat flux exit were not received for the same constraint frequencies.
基金supported in part by a project (Y6Y2581B11) funded by 2016 National Postdoctoral Program for Innovative Talentssupported by the National Nat-ural Science Foundation of China (NSFC)(11847612,11690022,11851302,11675243,11761141011)+1 种基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB21010200,XDB23000000)supported by the 2019 International Postdoctoral Exchange Fellowship Program。
文摘We present a general method of constructing unfactorizable on-shell amplitudes(amplitude basis) and build up their one-to-one correspondence to the independent and complete operator basis in effective field theory(EFT).We apply our method to the Standard Model EFT and identify the amplitude basis in dimensions 5 and 6,which correspond to the Weinberg operator and operators in the Warsaw basis,except for some linear combinations.
基金supported by the National Natural Science Foundation of China(Grant Nos.12022512,12035007,12175016,12005065,12074180)the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2020B0301030008)+3 种基金the Key-Area Research and Development Program of Guangdong Province(Grant No.2019B030330001)the Guangdong Basic and Applied Basic Research Fund(Grant No.2021A1515010317)the Key Project of Science and Technology of Guangzhou(Grant No.2019050001)the National Special Support Program for High-level Talents。
文摘Light-cone distribution amplitudes(LCDAs)are essential nonperturbative quantities for theoretical predictions of exclusive highenergy processes in quantum chromodynamics(QCD).We demonstrate the prospect of calculating LCDAs on a quantum computer by applying a recently proposed quantum algorithm,with staggered fermions,to the simulation of the LCDA in the(1+1)-dimensional Nambu-Jona-Lasinio(NJL)model on classical hardware.The agreement between the result from the classical simulation of the quantum algorithm and that from exact diagonalization justifies the proposed quantum algorithm.We find that the resulting LCDA in the NJL model exhibits features shared with the LCDAs obtained from the QCD.
基金Supported by the National Natural Science Foundation of China(11847168)the Fundamental Research Funds for the Central Universities of China(GK202003018)the Natural Science Foundation of Shannxi Province,China(2019JM-431,2019JQ-739)。
文摘CP violation may play an important role in baryogenesis in the early universe and should be examined comprehensively at colliders.We study the CP properties of HVV vertexes between Higgs and gauge boson pairs by defining a CP violation phase angle,which indicates the mixture of CP-even and CP-odd Higgs states in HVV in new physics.A series of HVV amplitudes,H→γγ,H-→V→γtt,and H→VV-→4f,with a CP phase angle are studied systematically to explicitly explain why CP violation can only be probed independently in the 4t pro-cess.We obtain a novel amplitude decomposition relation that illustrates that if two preconditions(multilinear mo-mentum dependent vertexes,and the current J_(μ) of V→l^(+)l^(-)is formally proportional to a photon's polarization vec-tor)are satisfied,a higher-point amplitude can be decomposed into a summation of a series of lower-point amp-litudes.As a practical example,the amplitude of the H→γV-→γtt and H→VV→4t processes can be decom-posed into a summation of many H→γγ amplitudes.We calculate these amplitudes in the framework of the on-shell scattering amplitude method,considering both massless and massive vector gauge bosons with the CP viola-tion phase angle.The above two approaches provide consistent results and clearly reveal the CP violation ξ depend-ence in the amplitudes.
基金Supported in part by the National Natural Science Foundation of China(12265009,12265010)the Project of Guizhou Provincial Department of Science and Technology(ZK[2021]024,ZK[2023]142)+1 种基金the Project of Guizhou Provincial Department of Education(KY[2021]030)the Chongqing Graduate Research and Innovation Foundation(ydstd1912)。
文摘Owing to the significant difference between the experimental measurements and the theoretical predictions of the standard model(SM)for the value of R(D)of the semileptonic decay B→Dtve,researchers speculate that this decay may be evidence of new physics beyond the SM.Usually,the D-meson twist-2,3 distribution amplitudes(DAs)Φ2;D(x,μ),d3:D(x,μ),and$g:D(x,μ)are the main error sources when perturbative QCD factorization and light-cone QCD sum rules are used to study B→Dtve.Therefore,it is important to obtain more reasonable and accurate behaviors for these DAs.Motivated by our previous work[Phys.Rev.D 104,no.1,016021(2021)]on pionic leading-twist DA,we revisit D-meson twist-2,3 DAsΦ2:D(x,μ),Φp3:D(x,μ),andΦσ3:D(x,μ).New sum rule formulae for the-moments of these three DAs are suggested for obtaining more accurate values.The light-cone harmonic oscillator models for the DAs are improved,and their parameters are determined by fitting the values of-moments via the least squares method.
基金B.F.is supported by Qiu-Shi Funding and the National Natural Science Foundation of China(NSFC)(11935013,11575156)R.H.is supported by the National Natural Science Foundation of China(NSFC)(11805102),Natural Science Foundation of Jiangsu Province(BK20180724)ShuangChuang Talent Program of Jiangsu Province。
文摘Motivated by the problem of expanding the single-trace tree-level amplitude of Einstein-Yang-Mills theory to the BCJ basis of Yang-Mills amplitudes,we present an alternative expansion formula in gauge invariant vector space.Starting from a generic vector space consisting of polynomials of momenta and polarization vectors,we define a new sub-space as a gauge invariant vector space by imposing constraints on the gauge invariant conditions.To characterize this sub-space,we compute its dimension and construct an explicit gauge invariant basis from it.We propose an expansion formula in this gauge invariant basis with expansion coefficients being linear combinations of the Yang-Mills amplitude,manifesting the gauge invariance of both the expansion basis and coefficients.With the help of quivers,we compute the expansion coefficients via differential operators and demonstrate the general expansion algorithm using several examples.
文摘New techniques for controlling the amplitudes of two orthogonal linearly polarized light are presented. One is based on adjusting the DC voltage into a Mach–Zehnder modulator(MZM) to alter the amplitude of the light traveling on the slow axis of a fiber into the modulator with little changes in the fast-axis light amplitude.Another is based on adjusting the input DC voltages of a dual-polarization MZM operating in the reverse direction, which enables independent control of the two input orthogonal linearly polarized light amplitudes.Experimental results demonstrate that more than 30 dB difference in slow-and fast-axis light power can be obtained by controlling an MZM input DC voltage, and over 24 dB independent power adjustment for light traveling on the slow and fast axes into a dual-polarization MZM.
基金Project supported by Beijing Natural Science Foundation(Grant No.1212014)the National Key Research and Development Program of China(Grant Nos.2017YFA0304900 and 2017YFA0402300)+4 种基金the National Natural Science Foundation of China(Grant Nos.11604334,11604177,and U2031125)the Key Research Program of the Chinese Academy of Sciences(Grant No.XDPB08-3)the Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics(Grant No.KF201807)the Fundamental Research Funds for the Central UniversitiesYouth Innovation Promotion Association CAS。
文摘We have theoretically and experimentally studied the dispersive signal of the Rydberg atomic electromagneticallyinduced transparency(EIT)Autler–Townes(AT)splitting spectra obtained using amplitude modulation of the microwave(MW)electric field.In addition to the two zero-crossing points interval△f_(zeros),the dispersion signal has two positive maxima with an interval defined as the shoulder interval△f_(sho),which is theoretically expected to be used to measure a much weaker MW electric field.The relationship of the MW field strength E_(MW)and△f_(sho)is experimentally studied at the MW frequencies of 31.6 GHz and 9.2 GHz respectively.The results show that△f_(sho)can be used to characterize the much weaker E_(MW)than that of△f_(zeros)and the traditional EIT–AT splitting interval△f_(m);the minimum E_(MW)measured by△f_(sho)is about 30 times smaller than that by△f_(m).As an example,the minimum E_(MW)at 9.2 GHz that can be characterized by△f_(sho)is 0.056 mV/cm,which is the minimum value characterized by the frequency interval using a vapor cell without adding any auxiliary fields.The proposed method can improve the weak limit and sensitivity of E_(MW)measured by the spectral frequency interval,which is important in the direct measurement of weak E_(MW).
基金financially supported by the Chinese State Key Laboratory of Ocean Engineering(Grant No.GKZD010068/084).
文摘In order to forecast the distribution of crest amplitudes and the occurrence of freak waves in a short crested coastal sea,a novel transformed linear simulation method is initially proposed in this paper.A Hermite transformation model expressed as a monotonic cubic polynomial serves as the foundation for the novel simulation technique.The wave crest amplitude exceedance probabilities of two sea states-one with a directional wave spectrum based on the measured wave elevation data at the Yura coast and the other with a typical directional JONSWAP wave spectrum-have been predicted using the novel simulation method that has been proposed.The likelihood that a particular critical wave crest amplitude will be exceeded is directly correlated with the probability that freak waves will occur.It is shown that the novel simulation approach suggested can provide predictions that are more precise than those obtained from the Rayleigh crest amplitude distribution model,the Jahns and Wheeler crest amplitude distribution model,or the conventional linear simulation method.This study also demonstrated that the nonlinear simulation method is less effective than the novel simulation method in terms of efficiency.
基金supported by the Department of Science and Technology Government of India,grant number SP/YO2019/1287(G)supported by Fronius India Solutions&Skill Centre,Bengaluru and CRF NITK Surathkal.
文摘Cold Metal Transfer-Based Wire Arc Directed Energy Deposition(CMT-WA-DED)presents a promising avenue for the rapid fabrication of components crucial to automotive,shipbuilding,and aerospace industries.However,the susceptibility to fatigue of CMT-WA-DED-produced AZ31 Mg alloy components has impeded their widespread adoption for critical load-bearing applications.In this study,a comprehensive investigation into the fatigue behaviour of WA-DED-fabricated AZ31 Mg alloy has been carried out and compared to commercially available wrought AZ31 alloy.Our findings indicate that the as-deposited parts exhibit a lower fatigue life than wrought Mg alloy,primarily due to poor surface finish,tensile residual stress,porosity,and coarse grain microstructure inherent in the WA-DED process.Low Plasticity Burnishing(LPB)treatment is applied to mitigate these issues,which induce significant plastic deformation on the surface.This treatment resulted in a remarkable improvement of fatigue life by 42%,accompanied by a reduction in surface roughness,grain refinement and enhancement of compressive residual stress levels.Furthermore,during cyclic deformation,WA-DED specimens exhibited higher plasticity and dislocation density compared to both wrought and WA-DED+LPB specimens.A higher fraction of Low Angle Grain Boundaries(LAGBs)in WA-DED specimens contributed to multiple crack initiation sites and convoluted crack paths,ultimately leading to premature failure.In contrast,wrought and WA-DED+LPB specimens displayed a higher percentage of High Angle Grain Boundaries(HAGBs),which hindered dislocation movement and resulted in fewer crack initiation sites and less complex crack paths,thereby extending fatigue life.These findings underscore the effectiveness of LPB as a post-processing technique to enhance the fatigue performance of WA-DED-fabricated AZ31 Mg alloy components.Our study highlights the importance of LPB surface treatment on AZ31 Mg components produced by CMT-WA-DED to remove surface defects,enabling their widespread use in load-bearing applications.
基金the National Natural Science Foundation of China(No.61601296,61201244)the Science and Technology Innovation Action Plan Project of Shanghai Science and Technology Commission(No.20511103500)the Talent Program of Shanghai University of Engineering Science(No.2018RC43)。
文摘In order to reduce the intrinsic interference of the filter bank multicarrier-quadrature amplitude modulation(FBMC-QAM)system,a novel filter optimization scheme based on discrete prolate spheroidal sequences(DPSS)is proposed.Firstly,a prototype filter function based on DPSS is designed,since the eigenvalue can be used as an indicator of the energy concentration of DPSS,so a threshold is set,and the sequence with the most concentrated energy is selected under the threshold,that is,the sequence with the eigenvalue higher than the threshold,and the prototype filter function is rewritten as a weighted sum function of multiple eigenvectors.Under the energy constraints of the filter,the relationship between the eigenvectors and the intrinsic interference function is established,and the function problem is transformed into an optimization problem for the weighted coefficients.Through the interior point method,the most suitable weight is found to obtain the minimum intrinsic interference result.Theoretical analysis and simulation results show that compared with the prototype filters such as Type1 and CaseC,the DPSS filter applying the proposed optimization algorithm can effectively suppress the intrinsic interference of the system and obtain a better bit error rate(BER)performance.