The undeformed chip thickness and grinding force are key parameters for revealing the material removal mechanism in the grinding process.However,they are difficult to be well expressed due to the ununiformed protrusio...The undeformed chip thickness and grinding force are key parameters for revealing the material removal mechanism in the grinding process.However,they are difficult to be well expressed due to the ununiformed protrusion height and random position distribution of abrasive grains on the abrasive wheel surface.This study investigated the distribution of undeformed chip thickness and grinding force considering the non-uniform characteristics of abrasive wheel in the grinding of K4002 nickel-based superalloy.First,a novel grinding force model was established through a kinematic-geometric analysis and a grain-workpiece contact analysis.Then,a series of grinding experiments were conducted for verifying the model.The results indicate that the distribution of undeformed chip thickness is highly consistent with the Gaussian distribution formula.The increase in the grinding depth mainly leads to an increase in the average value of Gaussian distribution.On the contrary,the increase in the workpiece infeed speed or the decrease in the grinding speed mainly increases the standard deviation of Gaussian distribution.The average and maximum errors of the grinding force model are 4.9%and 14.6%respectively,indicating that the model is of high predication accuracy.展开更多
Recent pulsar timing observations using MeerKAT of the eccentric binary millisecond pulsar,PSR J0514−4002E,have unveiled a companion with a mass in the mass gap,ranging from 2.09 M_(⊙)to 2.71 M_(⊙).This challenges c...Recent pulsar timing observations using MeerKAT of the eccentric binary millisecond pulsar,PSR J0514−4002E,have unveiled a companion with a mass in the mass gap,ranging from 2.09 M_(⊙)to 2.71 M_(⊙).This challenges conventional astrophysical scenarios for black hole formation.In this paper,we present an alternative explanation:PSR J0514−4002E could be in a PBH-NS binary,with the companion potentially being a primordial black hole formed during the early Universe’s first-order phase transition.The associated stochastic gravitational-wave background generated during this phase transition can account for the observed signal from the pulsar timing array,and the abundance of primordial black holes is consistent with constraints from LIGO-VirgoKAGRA.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.92160301,92060203,52175415 and 52205475)the Science Center for Gas Turbine Project(Nos.P2022-AB-Ⅳ-002-001 and P2023-B-Ⅳ-003-001)+3 种基金the Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology(No.JSKL2223K01)the Natural Science Foundation of Jiangsu Province(No.BK20210295)the Superior Postdoctoral Project of Jiangsu Province(No.2022ZB215)the Henan Science and Technology Public Relations Project(No.212102210445).
文摘The undeformed chip thickness and grinding force are key parameters for revealing the material removal mechanism in the grinding process.However,they are difficult to be well expressed due to the ununiformed protrusion height and random position distribution of abrasive grains on the abrasive wheel surface.This study investigated the distribution of undeformed chip thickness and grinding force considering the non-uniform characteristics of abrasive wheel in the grinding of K4002 nickel-based superalloy.First,a novel grinding force model was established through a kinematic-geometric analysis and a grain-workpiece contact analysis.Then,a series of grinding experiments were conducted for verifying the model.The results indicate that the distribution of undeformed chip thickness is highly consistent with the Gaussian distribution formula.The increase in the grinding depth mainly leads to an increase in the average value of Gaussian distribution.On the contrary,the increase in the workpiece infeed speed or the decrease in the grinding speed mainly increases the standard deviation of Gaussian distribution.The average and maximum errors of the grinding force model are 4.9%and 14.6%respectively,indicating that the model is of high predication accuracy.
基金supported by the National Natural Science Foundation of China(Grant No.12405056)the innovative research group of Hunan Province(Grant No.2024JJ1006)supported by the National Natural Science Foundation of China(Grant No.12433001).
文摘Recent pulsar timing observations using MeerKAT of the eccentric binary millisecond pulsar,PSR J0514−4002E,have unveiled a companion with a mass in the mass gap,ranging from 2.09 M_(⊙)to 2.71 M_(⊙).This challenges conventional astrophysical scenarios for black hole formation.In this paper,we present an alternative explanation:PSR J0514−4002E could be in a PBH-NS binary,with the companion potentially being a primordial black hole formed during the early Universe’s first-order phase transition.The associated stochastic gravitational-wave background generated during this phase transition can account for the observed signal from the pulsar timing array,and the abundance of primordial black holes is consistent with constraints from LIGO-VirgoKAGRA.
