In this paper, the generator set of R 〈 x1,x2 〉G is obtained in according to the group G = Gl（n,R）. The conditions of G = Gl（n, R） -equivalence of a pair of curves are found in terms of G = Gl（n, R）-invariants...In this paper, the generator set of R 〈 x1,x2 〉G is obtained in according to the group G = Gl（n,R）. The conditions of G = Gl（n, R） -equivalence of a pair of curves are found in terms of G = Gl（n, R）-invariants. And the independence of GL（n, R） -invariants is shown.展开更多
Combining wavelet transforms with conventional log differential curves is used to identify fractured sections is a new idea.In this paper,we first compute the mother wavelet transform of conventional logs and the wave...Combining wavelet transforms with conventional log differential curves is used to identify fractured sections is a new idea.In this paper,we first compute the mother wavelet transform of conventional logs and the wavelet decomposed signals are compared with fractures identified from image logs to determine the fracture-matched mother wavelet.Then the mother wavelet-based decomposed signal combined with the differential curves of conventional well logs create a fracture indicator curve,identifying the fractured zone.Finally the fracture density can be precisely evaluated by the linear relationship of the indicator curve and image log fracture density.This method has been successfully used to evaluate igneous reservoir fractures in the southern Songnan basin and the calculated density from the indicator curve and density from image logs are both basically consistent.展开更多
Lifetimes of the 2_(1)^(+),4_(1)^(+),7_(2)^(-),10_(2)^(+),12_(2)^(+),and 14_(1)^(+) states in 138 Nd populated via the 123 Sb(19 F,4n)138 Nd fusion–evaporation reaction were measured with the recoil distance Doppler ...Lifetimes of the 2_(1)^(+),4_(1)^(+),7_(2)^(-),10_(2)^(+),12_(2)^(+),and 14_(1)^(+) states in 138 Nd populated via the 123 Sb(19 F,4n)138 Nd fusion–evaporation reaction were measured with the recoil distance Doppler shift technique in combination with the differential decay curve method.The B(E2;2_(1)^(+)→0_(1)^(+))value fit well with the systematic trend in the Nd isotope chain and Grodzins rule,which proved that 138Nd is a transitional nucleus.展开更多
In this paper, we present a constructive proof of Luroth's theorem in differential case. We also give a method to find the inversion maps for general differential rational parametric equations. As a consequence, w...In this paper, we present a constructive proof of Luroth's theorem in differential case. We also give a method to find the inversion maps for general differential rational parametric equations. As a consequence, we prove that a differential rational curve always has a set of proper parametric equations.展开更多
The influences of pre-ageing temperature and natural ageing time on subsequent artificial age hardening behavior and precipitation sequence of new type Al-1.01Mg-0.O8Si-l.78Cu alloy were investigated by hardness test,...The influences of pre-ageing temperature and natural ageing time on subsequent artificial age hardening behavior and precipitation sequence of new type Al-1.01Mg-0.O8Si-l.78Cu alloy were investigated by hardness test, differential scanning calorimetry （DSC） test and transmission electronic microscopy （TEM） observations. When pre-ageing temperature is 20℃ （natural ageing）, the peak hardness of subsequent artificial aged alloy is lower than that of T6 treated alloy （negative effect）, while a positive effect appears when pre-ageing temperature is above 80℃. The size of needlelike /3-precipitate in subsequent artificial aged alloy is much coarser when pre-ageing temperature is 20℃, which causes a decrease in peak-hardness. The positive effect occurs again when natural ageing time is longer than 3 weeks. There are seven exothermic peaks in DSC curve of as-quenched alloy, while the number and height of exothermic peak decrease with increasing pre-ageing temperature and natural ageing time.展开更多
The lifetime of the 2^+1 state in ^106Cd populated via the ^94Zr(^16O,4n)^106Cd reaction has been measured with the Recoil Distance Doppler Shift technique in combination with the Differential Decay Curve Method.By su...The lifetime of the 2^+1 state in ^106Cd populated via the ^94Zr(^16O,4n)^106Cd reaction has been measured with the Recoil Distance Doppler Shift technique in combination with the Differential Decay Curve Method.By subtracting the contamination in the data,the mean lifetime of the I^π=2^+1633 keV state was determined as 9.9(12)ps.The B(E2)value calculated in this study is in good agreement with the experimental systematics and was compared to the shell model calculations.展开更多
This paper develops a novel approach and some main results on the varying-speed missile guided by pure proportional navigation(PPN)against a stationary target in the planar interception problem.The missile kinematic e...This paper develops a novel approach and some main results on the varying-speed missile guided by pure proportional navigation(PPN)against a stationary target in the planar interception problem.The missile kinematic equation is established in the arc-length domain based on the differential geometry theory,which eliminates the influence of time-varying missile speed.Then,the closed-form solutions of line-of-sight(LOS)rate,leading angle,closing speed,and curvature command are derived in the arc-length domain.The performance of the varyingspeed missile is analyzed,including the maximum relative distance,maximum curvature command,accurate path-to-go,and curvature increment.Additionally,the capture region is obtained considering the missile maneuvering acceleration limit.These new theoretical results could be extended to improve the performance of existing guidance laws designed under the constant-speed assumption.展开更多
文摘In this paper, the generator set of R 〈 x1,x2 〉G is obtained in according to the group G = Gl（n,R）. The conditions of G = Gl（n, R） -equivalence of a pair of curves are found in terms of G = Gl（n, R）-invariants. And the independence of GL（n, R） -invariants is shown.
基金sponsored by National Science and Technology Major Project of China (No. 2008 ZX 05009-001)
文摘Combining wavelet transforms with conventional log differential curves is used to identify fractured sections is a new idea.In this paper,we first compute the mother wavelet transform of conventional logs and the wavelet decomposed signals are compared with fractures identified from image logs to determine the fracture-matched mother wavelet.Then the mother wavelet-based decomposed signal combined with the differential curves of conventional well logs create a fracture indicator curve,identifying the fractured zone.Finally the fracture density can be precisely evaluated by the linear relationship of the indicator curve and image log fracture density.This method has been successfully used to evaluate igneous reservoir fractures in the southern Songnan basin and the calculated density from the indicator curve and density from image logs are both basically consistent.
基金This work was supported by the National Natural Science Foundation of China(Nos.U1932209,11975315,U1867210,and 11905134)the Leading Innovation Project(Nos.LC192209000701 and LC202309000201)+1 种基金the Continuous Basic Scientific Research Project(Nos.BJ20002501 and WDJC-2019-13)the China National Nuclear Corporation(No.FA18000201).
文摘Lifetimes of the 2_(1)^(+),4_(1)^(+),7_(2)^(-),10_(2)^(+),12_(2)^(+),and 14_(1)^(+) states in 138 Nd populated via the 123 Sb(19 F,4n)138 Nd fusion–evaporation reaction were measured with the recoil distance Doppler shift technique in combination with the differential decay curve method.The B(E2;2_(1)^(+)→0_(1)^(+))value fit well with the systematic trend in the Nd isotope chain and Grodzins rule,which proved that 138Nd is a transitional nucleus.
基金This research is supported in part by CNSF under an Outstanding Youth Grant(No. 69725002) by a "973" Project.
文摘In this paper, we present a constructive proof of Luroth's theorem in differential case. We also give a method to find the inversion maps for general differential rational parametric equations. As a consequence, we prove that a differential rational curve always has a set of proper parametric equations.
基金supported by the National Key Technology R&D Program of China under grant No.2007BAE38B01
文摘The influences of pre-ageing temperature and natural ageing time on subsequent artificial age hardening behavior and precipitation sequence of new type Al-1.01Mg-0.O8Si-l.78Cu alloy were investigated by hardness test, differential scanning calorimetry （DSC） test and transmission electronic microscopy （TEM） observations. When pre-ageing temperature is 20℃ （natural ageing）, the peak hardness of subsequent artificial aged alloy is lower than that of T6 treated alloy （negative effect）, while a positive effect appears when pre-ageing temperature is above 80℃. The size of needlelike /3-precipitate in subsequent artificial aged alloy is much coarser when pre-ageing temperature is 20℃, which causes a decrease in peak-hardness. The positive effect occurs again when natural ageing time is longer than 3 weeks. There are seven exothermic peaks in DSC curve of as-quenched alloy, while the number and height of exothermic peak decrease with increasing pre-ageing temperature and natural ageing time.
基金Supported by National Key Research and Development Program of China(2017YFF0106501)National Natural Science Foundation of China(11905134,11975315,U1932209,11575118,11605114)+3 种基金NSFC-CNNC Joint Project for Nuclear Technology Innovation(U1867210)Continuous Basic Scientific Research Project(WDJC-2019-13)Project funded by China Post-doctoral Science Foundation(2019M652999)and National Natural Science Foundation of Guangdong China(2016A030310042)。
文摘The lifetime of the 2^+1 state in ^106Cd populated via the ^94Zr(^16O,4n)^106Cd reaction has been measured with the Recoil Distance Doppler Shift technique in combination with the Differential Decay Curve Method.By subtracting the contamination in the data,the mean lifetime of the I^π=2^+1633 keV state was determined as 9.9(12)ps.The B(E2)value calculated in this study is in good agreement with the experimental systematics and was compared to the shell model calculations.
基金supported by the National Natural Science Foundation of China(Grant No.12002370).
文摘This paper develops a novel approach and some main results on the varying-speed missile guided by pure proportional navigation(PPN)against a stationary target in the planar interception problem.The missile kinematic equation is established in the arc-length domain based on the differential geometry theory,which eliminates the influence of time-varying missile speed.Then,the closed-form solutions of line-of-sight(LOS)rate,leading angle,closing speed,and curvature command are derived in the arc-length domain.The performance of the varyingspeed missile is analyzed,including the maximum relative distance,maximum curvature command,accurate path-to-go,and curvature increment.Additionally,the capture region is obtained considering the missile maneuvering acceleration limit.These new theoretical results could be extended to improve the performance of existing guidance laws designed under the constant-speed assumption.
