The high pressure waves generated due to muzzle blast flow of tank gun during firing is a critical issue to examine. The impulsive noise from the gun has various negative effects such as damage of human bodies, damage...The high pressure waves generated due to muzzle blast flow of tank gun during firing is a critical issue to examine. The impulsive noise from the gun has various negative effects such as damage of human bodies, damage of structures, creating an environmental, social problem and also military problems such as exposure of location of troops. This high pressure impulsive sound, generated during the blast flow, was studied and attenuated. An axisymmetric computational domain was constructed by employing Spalart Allmaras turbulence model. Approximately 90% of pressure and 20 dB of sound level are reduced due to the use of the three baffle silencer at the muzzle end of the gun barrel, in comparison with the tank gun without silencer. Also, the sound pressure level at different points in the ambient region shows the same attenuation in results. This study will be helpful to understand the blast wave characteristics and also to get a good idea to design silencer for large caliber weapon system.展开更多
Residual stress continues to be important issues in shipbuilding. This paper demonstrates how the heat affected zone that results from welding could be identified nondestructively using MBN （magnetic Barkhausen noise...Residual stress continues to be important issues in shipbuilding. This paper demonstrates how the heat affected zone that results from welding could be identified nondestructively using MBN （magnetic Barkhausen noise） technique. A stress concentration region was created by placing a weld bead on a marine steel plate used in ship construction. MBN measurements were made on the back surface of the welded plate along the weld direction and perpendicular to it in a line that crosses the weld bead. The stress distribution as deduced from the MBN measurements was found to be anisotropic in the material of the heat affected zone. The heat induced anisotropy was completely eliminated by shot peening the HAZ material as revealed by MBN intensity. It was concluded that the directional MBN measurements could be used to characterize the induced anisotropy and hence assess the thermal residual stresses distribution near a localized stresses concentration regions imposed by welding.展开更多
The speed of sound in quark matter is an important physical quantity for studying the properties and the spacetime evolution of quark-gluon plasma(QGP).The behavior of the speed of sound with respect to temperature an...The speed of sound in quark matter is an important physical quantity for studying the properties and the spacetime evolution of quark-gluon plasma(QGP).The behavior of the speed of sound with respect to temperature and density can reveal to some extent the equation of state and the phase structure of QGP.Building upon the previous studies on the speed of sound in symmetric quark matter,the formulae for calculating the speed of sound in asymmetric quark matter in the temperature-density space are further derived.The PNJL model is then used to calculate the dependence of the speed of sound on isospin asymmetry.Furthermore,the relationship between the magnitude of the speed of sound and the QCD phase structure is discussed,and the regions where the acoustic equation fails are indicated under different physical conditions.It is found that the boundary of vanishing sound speed in asymmetric quark matter is smaller than that in symmetric quark matter,meaning that the range where the acoustic wave equation fails in asymmetric quark matter is smaller than that in symmetric quark matter.The results also indicate that in most of the stable phase,the speed of sound in asymmetric quark matter is slightly larger than that in symmetric quark matter.展开更多
The crustal S-velocity structure and radial anisotropy along a dense linear portable seismic array with 64 broadband seismic stations were investigated from ambient noise tomography with about one-year-long ambient no...The crustal S-velocity structure and radial anisotropy along a dense linear portable seismic array with 64 broadband seismic stations were investigated from ambient noise tomography with about one-year-long ambient noise recordings. The array transverses the southern part of the central North China Craton(CNCC) and western NCC(WNCC) from east to west and reaches the adjacent Qilian Orogenic Belt(QOB). The phase velocity structures of Rayleigh waves at 5–35 s and Love waves at 5–30 s were measured. The crustal S-velocity structures(Vsv and Vsh) were constructed from the dispersion data(Rayleigh and Love waves,respectively) from point-wise linear inversion with prior information of the Moho depth and average crustal Vp/Vs ratio. The radial anisotropy along the profile was calculated based on the discrepancies between Vsv and Vsh as 2×(Vsh.Vsv)/(Vsh+Vsv). The results show distinct structural variations in the three major tectonic units. The crustal architecture in the southern CNCC is complicated and featured with wide-distributed low-velocity zones(LVZs), which may be a reflection of crustal modification resulting from Mesozoic-Cenozoic tectonics and magmatic activities. The pronounced positive radial anisotropy in the lower-lowermost crust beneath the Shanxi-Shaanxi Rift and the neighboring areas could be attributed to the underplating of mantle mafic-ultramafic materials during the Mesozoic-Cenozoic tectonic activation. In southern Ordos, the overall weak lateral velocity variations, relative high velocity and large-scale positive radial anisotropy in mid-lower crust probably suggest that the current crustal structure has preserved its Precambrian tectonic characteristics. The low-velocity westward-dipping sedimentary strata in the Ordos Block could be attributed to the Phanerozoic whole-basin tilting and the uneven erosion since late Cretaceous. Integrated with previous studies, the systematic comparison of crustal architecture was made between the southern and northern part of CNCC-WNCC. The similarities and differences may have a relation with the tectonic events and deformation histories experienced before and after the Paleoproterozoic amalgamation of the NCC. The nearly flat mid-crustal LVZ beneath the southern QOB weakens gradually as it extends to the east, which is a feature probably associated with crustal vertical superpositionand ductile shear deformation under the intensive compressional regime due to the northeastward growth and expansion of the Tibetan Plateau.展开更多
The electromagnetic transition between the nucleon and excited baryons has long been recognized as an important source of information for understanding strong interactions in the domain of quark confinement. We study ...The electromagnetic transition between the nucleon and excited baryons has long been recognized as an important source of information for understanding strong interactions in the domain of quark confinement. We study the electromagnetic properties of the excitation of the negative parity the N~*(1535) resonances in the nonrelativistic constituent quark model at large momentum transfers and have performed a calculation the longitudinal and transverse helicity amplitudes. Since the helicity amplitudes depend strongly on the quark wave function in this paper, we consider the baryon as a simple, non-relativistically three-body quark model and also consider a hypercentral potential scheme for the internal baryon structure, which makes three-body forces among three quarks. Since the hyper central potential depends only on the hyper radius, therefore, the Cornell potential which is a combination of the Coulombic-like term plus a linear confining term is considered as the potential for interaction between quarks. In our work, in solving the Schrodinger equation with the Cornell potential, the Nikiforov–Uvarov method employed, and the analytic eigen-energies and eigen-functions obtained. By using the obtained eigen-functions, the transition amplitudes calculated. We show that our results in the range Q^2> 2GeV^2 lead to an overall better agreement with the experimental data in comparison with the other three non-relativistic quark models.展开更多
In this paper an investigation into dust acoustic sofitary waves （DASWs） in the presence of superthermM electrons and ions in a magnetized plasma with cold dust gains and trapped electrons is discussed. The dynamic ...In this paper an investigation into dust acoustic sofitary waves （DASWs） in the presence of superthermM electrons and ions in a magnetized plasma with cold dust gains and trapped electrons is discussed. The dynamic of both electrons and ions is simulated by the generalized Lorentzian （κ） distribution function （DF）. The dust grains are cold and their dynamics are studied by hydrodynamic equations. The basic set of fluid equations is reduced to modified Korteweg-de Vries （mKdV） equation using Reductive Perturbation Theory （RPT）. Two types of solitary waves, fast and slow dust acoustic soliton （DAS） exist in this plasma. Caiculations reveal that compressive solitary structures are possibly propagated in the plasma where dust grains are negatively （or positively） charged. The properties of DASs are also investigated numerically.展开更多
Objective：To observe the curative effect of acupuncture plus medicine in treating ovulatory dysfunctional infertility.Method：All 36 cases with anovulatory infertility were randomly allocated into a control group （1...Objective：To observe the curative effect of acupuncture plus medicine in treating ovulatory dysfunctional infertility.Method：All 36 cases with anovulatory infertility were randomly allocated into a control group （19 cases） and an observation group （17 cases）.The cases in the control group were treated with 50 mg of oral administration Clomiphene once a day for 5 d,and 50 menstrual cycles were observed.The cases in the observation group were treated with combined acupuncture and the same medication as those in the control group and 45 menstrual cycles were observed.During the treatment sessions,the follicular development,ovulation,thickness of the endometrium,cervical mucus and pelvic fluid were observed and recorded.Results：The cases in the observation group showed significantly higher ovulation and pregnancy rates,along with thickening of the endometrium.In addition,no luteinized unruptured follicle syndrome （LUFS） occurred in the observation group.Conclusion：Acupuncture coupled with oral administration Clomiphene can obtain higher ovulation and conception rates than oral Clomiphene alone.展开更多
Influence induced by Raman effect on the noise characteristics of a depleted and lossy dual pump fiber optical parametric amplifier （FOPA） is investigated. Taking the Raman effect into account, the modified coupled ...Influence induced by Raman effect on the noise characteristics of a depleted and lossy dual pump fiber optical parametric amplifier （FOPA） is investigated. Taking the Raman effect into account, the modified coupled amplitude equations are fh-stly built, then the influences of Raman effect on the Stokes and anti-Stokes wavelengths with different initial signal powers are further analyzed. Besides, the effect on the FOPA gain is also shown with the same initial signal power and constant noise figure （NF）.展开更多
基金Project(NRF-2010-013-D00007) supported by the National Research Foundation of KoreaProject supported by 2010 Year Research Professor Fund of Gyeongsang National University, Korea and NIIED Korea
文摘The high pressure waves generated due to muzzle blast flow of tank gun during firing is a critical issue to examine. The impulsive noise from the gun has various negative effects such as damage of human bodies, damage of structures, creating an environmental, social problem and also military problems such as exposure of location of troops. This high pressure impulsive sound, generated during the blast flow, was studied and attenuated. An axisymmetric computational domain was constructed by employing Spalart Allmaras turbulence model. Approximately 90% of pressure and 20 dB of sound level are reduced due to the use of the three baffle silencer at the muzzle end of the gun barrel, in comparison with the tank gun without silencer. Also, the sound pressure level at different points in the ambient region shows the same attenuation in results. This study will be helpful to understand the blast wave characteristics and also to get a good idea to design silencer for large caliber weapon system.
文摘Residual stress continues to be important issues in shipbuilding. This paper demonstrates how the heat affected zone that results from welding could be identified nondestructively using MBN （magnetic Barkhausen noise） technique. A stress concentration region was created by placing a weld bead on a marine steel plate used in ship construction. MBN measurements were made on the back surface of the welded plate along the weld direction and perpendicular to it in a line that crosses the weld bead. The stress distribution as deduced from the MBN measurements was found to be anisotropic in the material of the heat affected zone. The heat induced anisotropy was completely eliminated by shot peening the HAZ material as revealed by MBN intensity. It was concluded that the directional MBN measurements could be used to characterize the induced anisotropy and hence assess the thermal residual stresses distribution near a localized stresses concentration regions imposed by welding.
文摘The speed of sound in quark matter is an important physical quantity for studying the properties and the spacetime evolution of quark-gluon plasma(QGP).The behavior of the speed of sound with respect to temperature and density can reveal to some extent the equation of state and the phase structure of QGP.Building upon the previous studies on the speed of sound in symmetric quark matter,the formulae for calculating the speed of sound in asymmetric quark matter in the temperature-density space are further derived.The PNJL model is then used to calculate the dependence of the speed of sound on isospin asymmetry.Furthermore,the relationship between the magnitude of the speed of sound and the QCD phase structure is discussed,and the regions where the acoustic equation fails are indicated under different physical conditions.It is found that the boundary of vanishing sound speed in asymmetric quark matter is smaller than that in symmetric quark matter,meaning that the range where the acoustic wave equation fails in asymmetric quark matter is smaller than that in symmetric quark matter.The results also indicate that in most of the stable phase,the speed of sound in asymmetric quark matter is slightly larger than that in symmetric quark matter.
基金supported by the National Natural Science Foundation of China(Grant Nos.41225016,91414301&41688103)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB03010802)
文摘The crustal S-velocity structure and radial anisotropy along a dense linear portable seismic array with 64 broadband seismic stations were investigated from ambient noise tomography with about one-year-long ambient noise recordings. The array transverses the southern part of the central North China Craton(CNCC) and western NCC(WNCC) from east to west and reaches the adjacent Qilian Orogenic Belt(QOB). The phase velocity structures of Rayleigh waves at 5–35 s and Love waves at 5–30 s were measured. The crustal S-velocity structures(Vsv and Vsh) were constructed from the dispersion data(Rayleigh and Love waves,respectively) from point-wise linear inversion with prior information of the Moho depth and average crustal Vp/Vs ratio. The radial anisotropy along the profile was calculated based on the discrepancies between Vsv and Vsh as 2×(Vsh.Vsv)/(Vsh+Vsv). The results show distinct structural variations in the three major tectonic units. The crustal architecture in the southern CNCC is complicated and featured with wide-distributed low-velocity zones(LVZs), which may be a reflection of crustal modification resulting from Mesozoic-Cenozoic tectonics and magmatic activities. The pronounced positive radial anisotropy in the lower-lowermost crust beneath the Shanxi-Shaanxi Rift and the neighboring areas could be attributed to the underplating of mantle mafic-ultramafic materials during the Mesozoic-Cenozoic tectonic activation. In southern Ordos, the overall weak lateral velocity variations, relative high velocity and large-scale positive radial anisotropy in mid-lower crust probably suggest that the current crustal structure has preserved its Precambrian tectonic characteristics. The low-velocity westward-dipping sedimentary strata in the Ordos Block could be attributed to the Phanerozoic whole-basin tilting and the uneven erosion since late Cretaceous. Integrated with previous studies, the systematic comparison of crustal architecture was made between the southern and northern part of CNCC-WNCC. The similarities and differences may have a relation with the tectonic events and deformation histories experienced before and after the Paleoproterozoic amalgamation of the NCC. The nearly flat mid-crustal LVZ beneath the southern QOB weakens gradually as it extends to the east, which is a feature probably associated with crustal vertical superpositionand ductile shear deformation under the intensive compressional regime due to the northeastward growth and expansion of the Tibetan Plateau.
文摘The electromagnetic transition between the nucleon and excited baryons has long been recognized as an important source of information for understanding strong interactions in the domain of quark confinement. We study the electromagnetic properties of the excitation of the negative parity the N~*(1535) resonances in the nonrelativistic constituent quark model at large momentum transfers and have performed a calculation the longitudinal and transverse helicity amplitudes. Since the helicity amplitudes depend strongly on the quark wave function in this paper, we consider the baryon as a simple, non-relativistically three-body quark model and also consider a hypercentral potential scheme for the internal baryon structure, which makes three-body forces among three quarks. Since the hyper central potential depends only on the hyper radius, therefore, the Cornell potential which is a combination of the Coulombic-like term plus a linear confining term is considered as the potential for interaction between quarks. In our work, in solving the Schrodinger equation with the Cornell potential, the Nikiforov–Uvarov method employed, and the analytic eigen-energies and eigen-functions obtained. By using the obtained eigen-functions, the transition amplitudes calculated. We show that our results in the range Q^2> 2GeV^2 lead to an overall better agreement with the experimental data in comparison with the other three non-relativistic quark models.
文摘In this paper an investigation into dust acoustic sofitary waves （DASWs） in the presence of superthermM electrons and ions in a magnetized plasma with cold dust gains and trapped electrons is discussed. The dynamic of both electrons and ions is simulated by the generalized Lorentzian （κ） distribution function （DF）. The dust grains are cold and their dynamics are studied by hydrodynamic equations. The basic set of fluid equations is reduced to modified Korteweg-de Vries （mKdV） equation using Reductive Perturbation Theory （RPT）. Two types of solitary waves, fast and slow dust acoustic soliton （DAS） exist in this plasma. Caiculations reveal that compressive solitary structures are possibly propagated in the plasma where dust grains are negatively （or positively） charged. The properties of DASs are also investigated numerically.
文摘Objective：To observe the curative effect of acupuncture plus medicine in treating ovulatory dysfunctional infertility.Method：All 36 cases with anovulatory infertility were randomly allocated into a control group （19 cases） and an observation group （17 cases）.The cases in the control group were treated with 50 mg of oral administration Clomiphene once a day for 5 d,and 50 menstrual cycles were observed.The cases in the observation group were treated with combined acupuncture and the same medication as those in the control group and 45 menstrual cycles were observed.During the treatment sessions,the follicular development,ovulation,thickness of the endometrium,cervical mucus and pelvic fluid were observed and recorded.Results：The cases in the observation group showed significantly higher ovulation and pregnancy rates,along with thickening of the endometrium.In addition,no luteinized unruptured follicle syndrome （LUFS） occurred in the observation group.Conclusion：Acupuncture coupled with oral administration Clomiphene can obtain higher ovulation and conception rates than oral Clomiphene alone.
基金supported by the National Basic Research Program of China (973 Program) (No.2010CB328304)
文摘Influence induced by Raman effect on the noise characteristics of a depleted and lossy dual pump fiber optical parametric amplifier （FOPA） is investigated. Taking the Raman effect into account, the modified coupled amplitude equations are fh-stly built, then the influences of Raman effect on the Stokes and anti-Stokes wavelengths with different initial signal powers are further analyzed. Besides, the effect on the FOPA gain is also shown with the same initial signal power and constant noise figure （NF）.
