In the present paper, the establishment of a systematic multi-barycenter mechanics is based on the multi-particle mechanics. The new theory perfects the basic theoretical system of classical mechanics, which finds the...In the present paper, the establishment of a systematic multi-barycenter mechanics is based on the multi-particle mechanics. The new theory perfects the basic theoretical system of classical mechanics, which finds the law of mutual interaction between particle groups, reveals the limitations of Newton’s third law, discovers the principle of the intrinsic relationship between gravity and tidal force, reasonably interprets the origin and change laws for the rotation angular momentum of galaxies and stars and so on. By applying new theory, the multi-body problem can be transformed into a special two-body problem and for which an approximate solution method is proposed, the motion law of each particle can be roughly obtained.展开更多
The tidal interactions of planets affect the stellar evolutionary status and the constraint of their physical parameters by gyrochronology.In this work,we incorporate the tidal interaction and magnetic braking of the ...The tidal interactions of planets affect the stellar evolutionary status and the constraint of their physical parameters by gyrochronology.In this work,we incorporate the tidal interaction and magnetic braking of the stellar wind into MESA and calculate a large grid of 25,000 models,covering planets with masses of 0.1–13.0MJ with different orbital distances that orbit late-type stars of different metallicities.We also explore the effect of different stellar initial rotations on the tidal interactions.Our results show that in the case of tidal inward migration,the stellar rotation periods are always lower than that of the star without planet before the planet is engulfed and the difference in the rotation period of its host star always increases with time.After the planet is engulfed,the stellar rotation periods are still lower than that of star without planet,but the difference of periods can be quickly eliminated if the star has a thick convective envelope(smaller mass and larger metallicity),regardless of the mass of the planet and the initial rotation period of the star.In the case of stars with thinner convective envelopes(larger mass and smaller metallicity),the stars will be spun up and remain the faster rotation in a long time.Meanwhile,the planet is easily swallowed and the period differences are large if the initial rotation period of its host star is higher.Finally,we also study the evolution of WASP-19 and estimate the range of tidal quality parameter Q_(*)^(')=(4.6±0.9)×10^(6)and the initial semimajor axis as(0.035±0.004)au.展开更多
Blade rubbing faults cause detrimental impact on the operation of aeroengines. Most of the existing studies on blade rubbing in the shaft-disk-blade-casing(SDBC) system have overlooked the elastic deformation of the b...Blade rubbing faults cause detrimental impact on the operation of aeroengines. Most of the existing studies on blade rubbing in the shaft-disk-blade-casing(SDBC) system have overlooked the elastic deformation of the blade, while some only consider the whirl of the rotor, neglecting its spin. To address these limitations, this paper proposes a dynamic model with large rotation for the SDBC system. The model incorporates the spin and whirl of the rotor, enabling the realistic reproduction of multiblade rubbing faults. To verify the accuracy of the SDBC model with large rotation and demonstrate its capability to effectively consider the rotational effects such as the centrifugal stiffening and gyroscopic effects, the natural characteristics and dynamic responses of the proposed model are compared with those obtained from reported research and experimental results. Furthermore, the effects of the rotating speed, contact stiffness,and blade number on the dynamic characteristics of the SDBC system with multi-blade rubbing are investigated. The results indicate that the phase angle between the rotor deflection and the unbalance excitation force increases with the increasing rotating speed,which significantly influences the rubbing penetration of each blade. The natural frequency of the SDBC system with rubbing constrain can be observed in the acceleration response of the casing and the torsional response of the shaft, and the frequency is related to the contact stiffness. Moreover, the vibration amplitude increases significantly with the product of the blade number under rubbing, and the rotating frequency approaches the natural frequency of the SDBC system. The proposed model can provide valuable insight for the fault diagnosis of rubbing in bladed rotating machinery.展开更多
Strangeon stars,which are proposed to describe the nature of pulsar-like compact stars,have passed various observational tests.The maximum mass of a non-rotating strangeon star could be high,which implies that the rem...Strangeon stars,which are proposed to describe the nature of pulsar-like compact stars,have passed various observational tests.The maximum mass of a non-rotating strangeon star could be high,which implies that the remnants of binary strangeon star mergers could even be long-lived massive strangeon stars.We study rigidly rotating strangeon stars in the slowly rotating approximation,using the Lennard-Jones model for the equation of state.Rotation can significantly increase the maximum mass of strangeon stars with unchanged baryon numbers,enlarging the mass-range of long-lived strangeon stars.During spin-down after merger,the decrease of radius of the remnant will lead to the release of gravitational energy.Taking into account the efficiency of converting the gravitational energy luminosity to the observed X-ray luminosity,we find that the gravitational energy could provide an alternative energy source for the plateau emission of X-ray afterglow.The fitting results of X-ray plateau emission of some short gamma-ray bursts suggest that the magnetic dipole field strength of the remnants can be much smaller than that of expected when the plateau emission is powered only by spin-down luminosity of magnetars.展开更多
During the long term evolution of globular clusters(GCs), some member stars are lost to the field. The recently found nitrogen-rich(N-rich) metal-poor field stars are promising candidates of these GC escapees, since N...During the long term evolution of globular clusters(GCs), some member stars are lost to the field. The recently found nitrogen-rich(N-rich) metal-poor field stars are promising candidates of these GC escapees, since N enhancement is the fingerprint of chemically enhanced populations in GCs. In this work, we discuss the possibility of identifying N-rich metal-poor field stars with the upcoming Chinese Space Station Telescope(CSST). We focus on the main survey camera with NUV, u, g, r, i, z, y filters and slitless spectrograph with a resolution about 200.The combination of UV sensitive equipment and prominent N-related molecular lines in the UV band bodes well for the identification: the color–color diagram of(u-g) versus(g-r) is capable of separating N-rich field stars from normal halo stars, if metallicity can be estimated without using the information on u-band photometry.Besides, the synthetic spectra show that a signal-to-noise ratio of 10 is sufficient to identify N-rich field stars. In the near future, a large sample of N-rich field stars found by CSST, combined with state-of-the-art N-body simulations will be crucial to deciphering GC-Galaxy co-evolution.展开更多
Can pulsar-like compact objects release further huge free energy besides the kinematic energy of rotation?This is actually relevant to the equation of state of cold supra-nuclear matter,which is still under hot debate...Can pulsar-like compact objects release further huge free energy besides the kinematic energy of rotation?This is actually relevant to the equation of state of cold supra-nuclear matter,which is still under hot debate.Enormous energy is surely needed to understand various observations,such asγ-ray bursts,fast radio bursts and softγ-ray repeaters.In this paper,the elastic/gravitational free energy of solid strangeon stars is revisited for strangeon stars,with two anisotropic models to calculate in general relativity.It is found that huge free energy(>10^(46)erg)could be released via starquakes,given an extremely small anisotropy((p_(t)-p_(r))/p_(r)~10^(-4),with pt/pr the tangential/radial pressure),implying that pulsar-like stars could have great potential of free energy release without extremely strong magnetic fields in the solid strangeon star model.展开更多
This study investigated the formation mechanism of new grains due to twin–twin intersections in a coarse-grained Mg–6Al–3Sn–2Zn alloy during different strain rates of an isothermal compression.The results of elect...This study investigated the formation mechanism of new grains due to twin–twin intersections in a coarse-grained Mg–6Al–3Sn–2Zn alloy during different strain rates of an isothermal compression.The results of electron backscattered diffraction investigations showed that the activated twins were primarily{1012}tension twins,and 60°<1010>boundaries formed due to twin–twin intersections under different strain rates.Isolated twin variants with 60°<1010>boundaries transformed into new grains through lattice rotations at a low strain rate(0.01 s^(−1)).At a high strain rate(10 s^(−1)),the regions surrounded by subgrain boundaries through high-density dislocation arrangement and the 60°<1010>boundaries transformed into new grains via dynamic recrystallization.展开更多
The Gaia DR3 parallax approach was used to estimate the absolute parameters of 2375δScuti stars from the ASAS catalog.The selected stars have a variety of observational characteristics,with a higher than 80%probabili...The Gaia DR3 parallax approach was used to estimate the absolute parameters of 2375δScuti stars from the ASAS catalog.The selected stars have a variety of observational characteristics,with a higher than 80%probability of beingδScuti stars.We have displayed all the stars in the Hertzsprung-Russell diagram along with theδScuti instability strip,the Zero Age Main Sequence and the Terminal Age Main Sequence.Then,we determined which fundamental and overtone modes each star belongs to using pulsation constant(Q)calculations.In addition,we evaluated the parameters in the Q calculation equation using three machine learning methods,which showed that surface gravity and temperature have the greatest effect on its calculation.The Period-Luminosity(P-L)relationship of theδScuti stars was also revisited.Eventually,using least squares linear regression,we made four linear fits for fundamental and overtone modes and updated their relationships.展开更多
Recent research in cross-domain intelligence fault diagnosis of machinery still has some problems,such as relatively ideal speed conditions and sample conditions.In engineering practice,the rotational speed of the mac...Recent research in cross-domain intelligence fault diagnosis of machinery still has some problems,such as relatively ideal speed conditions and sample conditions.In engineering practice,the rotational speed of the machine is often transient and time-varying,which makes the sample annotation increasingly expensive.Meanwhile,the number of samples collected from different health states is often unbalanced.To deal with the above challenges,a complementary-label(CL)adversarial domain adaptation fault diagnosis network(CLADAN)is proposed under time-varying rotational speed and weakly-supervised conditions.In the weakly supervised learning condition,machine prior information is used for sample annotation via cost-friendly complementary label learning.A diagnosticmodel learning strategywith discretized category probabilities is designed to avoidmulti-peak distribution of prediction results.In adversarial training process,we developed virtual adversarial regularization(VAR)strategy,which further enhances the robustness of the model by adding adversarial perturbations in the target domain.Comparative experiments on two case studies validated the superior performance of the proposed method.展开更多
Open clusters are the basic building blocks that serve as a laboratory for the study of young stellar populations in the Milky Way.Variable stars in open clusters provide a unique way to accurately probe the internal ...Open clusters are the basic building blocks that serve as a laboratory for the study of young stellar populations in the Milky Way.Variable stars in open clusters provide a unique way to accurately probe the internal structure,temporal and dynamical evolutionary stages of individual stars and the host cluster.The most powerful tool for such studies is time-domain photometric observations.This paper follows the route of our previous work,concentrating on a photometric search for variable stars in NGC 884.The target cluster is the companion of NGC869,forming the well-known double cluster system that is gravitationally bound.From the observation run in 2016 November,a total of 9247 B-band CCD images and 8218Ⅴ-band CCD images were obtained.We detected a total of 15 stars with variability in visual brightness,including five Be stars,three eclipsing binaries,and seven of unknown types.Two new variable stars were discovered in this work.We also compared the variable star content of NGC 884 with its companion NGC 869.展开更多
Additive friction stir deposition(AFSD)is a novel structural repair and manufacturing technology has become a research hotspot at home and abroad in the past five years.In this work,the microstructural evolution and m...Additive friction stir deposition(AFSD)is a novel structural repair and manufacturing technology has become a research hotspot at home and abroad in the past five years.In this work,the microstructural evolution and mechanical performance of the Al-Mg-Si alloy plate repaired by the preheating-assisted AFSD process were investigated.To evaluate the tool rotation speed and substrate preheating for repair quality,the AFSD technique was used to additively repair 5 mm depth blind holes on 6061 aluminum alloy substrates.The results showed that preheat-assisted AFSD repair significantly improved joint bonding and joint strength compared to the control non-preheat substrate condition.Moreover,increasing rotation speed was also beneficial to improve the metallurgical bonding of the interface and avoid volume defects.Under preheating conditions,the UTS and elongation were positively correlated with rotation speed.Under the process parameters of preheated substrate and tool rotation speed of 1000 r/min,defect-free specimens could be obtained accompanied by tensile fracture occurring in the substrate rather than the repaired zone.The UTS and elongation reached the maximum values of 164.2MPa and 13.4%,which are equivalent to 99.4%and 140%of the heated substrate,respectively.展开更多
A concept of ensemble averaged stellar reactors is developed to study the dynamics of processes occurring in stars, allocated in the ~200 pc solar neighborhood. According to the effective temperature value, four stell...A concept of ensemble averaged stellar reactors is developed to study the dynamics of processes occurring in stars, allocated in the ~200 pc solar neighborhood. According to the effective temperature value, four stellar classes are identified, for which the correlation coefficients and standard deviation are counted. The theory of the buoyancy terrestial elements is generalized to stellar systems. It was suggested that stars are over-heated due to the shift parameters of the nuclear processes occurring inside the stars, which leads to the synthesis of transuranium elements until the achievement of a critical nuclear mass and star explosion. The heavy transuranium elements sink downward and are concentrated in the stellar depth layers. The physical explanation of the existence of the critical Chandrasekhar star limit has been offered. Based on the spatial analysis of overheated stars, it was suggested that the withdrawal of the stellar reactor from the equilibrium state is a consequence of extragalactic compression inside the galaxy arm due to the arm spirality (not to be confused with the spirality of the galaxy itself).展开更多
Purpose: To present a protocol of a dual-field rotational (DFR) total skin electron therapy (TSET) and to provide an assessment of clinical implementation, dosimetry properties, and skin dose evaluation. Methods and M...Purpose: To present a protocol of a dual-field rotational (DFR) total skin electron therapy (TSET) and to provide an assessment of clinical implementation, dosimetry properties, and skin dose evaluation. Methods and Materials: The DFR-TSET combined the Stanford 6-field and McGill rotational methods. Dual 6 MeV electron beams in high dose total skin electron mode were used for DFR-TSET on a commercial linac. Beam profiles and dosimetric properties were measured using solid phantoms. The dose rate at expanded source-to-surface distance (SSD) was a combination of static rate and rotational rate. In vivo dosimetry of patient skin was performed on patients’ skin using film, metal oxide semiconductor field-effect transistors (MOSFET), and optically stimulated luminescent dosimeters (OSLD). Results: Dual field rotational total skin electron therapy exhibited good (≤±10%) uniformity in the beam profiles in the vertical direction at an extended SSD of 332 cm with a gantry angulation of ±20˚ deviated from the horizontal direction. In-vivo measurements confirmed acceptable uniformity of the patients’ total body surfaces and revealed anatomically self-blocked or shielded areas where underdosing occurred. Conclusions: The clinical implementation of DFR-TSET effectively utilizes the special mode on a linac. This technique provides short beam-on times, uniform dose distribution, large treatment field, and reduced dose of x-ray contamination to the patients. In-vivo measurements indicate satisfactory delivery and dose uniformity of the prescribed dose. Electron boost fields are recommended at normal SSDs to address underdosed areas.展开更多
The effects of equilibrium toroidal rotation during edge-localized mode(ELM)mitigated by resonant magnetic perturbation(RMP)are studied with the experimental equilibria of the EAST tokamak based on the four-field mode...The effects of equilibrium toroidal rotation during edge-localized mode(ELM)mitigated by resonant magnetic perturbation(RMP)are studied with the experimental equilibria of the EAST tokamak based on the four-field model in the BOUT++code.As the two main parameters to determine the toroidal rotation profiles,the rotation shear and magnitudes were separately scanned to investigate their roles in the impact of RMPs on peeling-ballooning(P-B)modes.On one hand,the results show that strong toroidal rotation shear is favorable for the enhancement of the self-generated E×B shearing rate<ω_(E×B)>with RMPs,leading to significant ELM mitigation with RMP in the stronger toroidal rotation shear region.On the other hand,toroidal rotation magnitudes may affect ELM mitigation by changing the penetration of the RMPs,more precisely the resonant components.RMPs can lead to a reduction in the pedestal energy loss by enhancing the multimode coupling in the turbulence transport phase.The shielding effects on RMPs increase with the toroidal rotation magnitude,leading to the enhancement of the multimode coupling with RMPs to be significantly weakened.Hence,the reduction in pedestal energy loss by RMPs decreased with the rotation magnitude.In brief,the results show that toroidal rotation plays a dual role in ELM mitigation with RMP by changing the shielding effects of plasma by rotation magnitude and affecting<ω_(E×B)>by rotation shear.In the high toroidal rotation region,toroidal rotation shear is usually strong and hence plays a dominant role in the influence of RMP on P-B modes,whereas in the low rotation region,toroidal rotation shear is weak and has negligible impact on P-B modes,and the rotation magnitude plays a dominant role in the influence of RMPs on the P-B modes by changing the field penetration.Therefore,the dual role of toroidal rotation leads to stronger ELM mitigation with RMP,which may be achieved both in the low toroidal rotation region and the relatively high rotation region that has strong rotational shear.展开更多
The origin of intermediate helium (He)-rich hot subdwarfs is still unclear.Previous studies have suggested that some surviving Type Ia supernovae (SNe Ia) companions from the white dwarf+main-sequence (WD+MS)channel m...The origin of intermediate helium (He)-rich hot subdwarfs is still unclear.Previous studies have suggested that some surviving Type Ia supernovae (SNe Ia) companions from the white dwarf+main-sequence (WD+MS)channel may contribute to the intermediate He-rich hot subdwarfs.However,previous studies ignored the impact of atomic diffusion on the post-explosion evolution of surviving companion stars of SNe Ia,leading to the aspect that they could not explain the observed surface He abundance of intermediate He-rich hot subdwarfs.In this work,by taking the atomic diffusion and stellar wind into account,we trace the surviving companions of SNe Ia from the WD+MS channel using the one-dimensional stellar evolution code MESA until they evolve into hot subdwarfs.We find that the surface He-abundances of our surviving companion models during their core He-burning phases are in a range of-1■log(N_(He) N_(H))■0,which are consistent with those observed in intermediate He-rich hot subdwarfs.This seems to further support the notion that it is possible for surviving companions of SNe Ia in the WD+MS channel to form some intermediate He-rich hot subdwarfs.展开更多
Purpose-Under the high-speed operating conditions,the effects of wheelset elastic deformation on the wheel rail dynamic forces will become more notable compared to the low-speed condition.In order to meet different an...Purpose-Under the high-speed operating conditions,the effects of wheelset elastic deformation on the wheel rail dynamic forces will become more notable compared to the low-speed condition.In order to meet different analysis requirements and selecting appropriate models to analyzing the wheel rail interaction,it is crucial to understand the influence of wheelset flexibility on the wheel-rail dynamics under different speeds and track excitations condition.Design/methodology/approach-The wheel rail contact points solving method and vehicle dynamics equations considering wheelset flexibility in the trajectory body coordinate system were investigated in this paper.As for the wheel-rail contact forces,which is a particular force element in vehicle multibody system,a method for calculating the Jacobian matrix of the wheel-rail contact force is proposed to better couple the wheel-rail contact force calculation with the vehicle dynamics response calculation.Based on the flexible wheelset modeling approach in this paper,two vehicle dynamic models considering the wheelset as both elastic and rigid bodies are established,two kinds of track excitations,namely normal measured track irregularities and short-wave irregularities are used,wheel-rail geometric contact characteristic and wheel-rail contact forces in both time and frequency domains are compared with the two models in order to study the influence of flexible wheelset rotation effect on wheel rail contact force.Findings-Under normal track irregularity excitations,the amplitudes of vertical,longitudinal and lateral forces computed by the flexible wheelset model are smaller than those of the rigid wheelset model,and the virtual penetration and equivalent contact patch are also slightly smaller.For the flexible wheelset model,the wheel rail longitudinal and lateral creepages will also decrease.The higher the vehicle speed,the larger the differences in wheel-rail forces computed by the flexible and rigid wheelset model.Under track short-wave irregularity excitations,the vertical force amplitude computed by the flexible wheelset is also smaller than that of the rigid wheelset.However,unlike the excitation case of measured track irregularity,under short-wave excitations,for the speed within the range of 200 to 350 km/h,the difference in the amplitude of the vertical force between the flexible and rigid wheelset models gradually decreases as the speed increase.This is partly due to the contribution of wheelset's elastic vibration under short-wave excitations.For low-frequency wheel-rail force analysis problems at speeds of 350 km/h and above,as well as high-frequency wheel-rail interaction analysis problems under various speed conditions,the flexible wheelset model will give results agrees better with the reality.Originality/value-This study provides reference for the modeling method of the flexible wheelset and the coupling method of wheel-rail contact force to the vehicle multibody dynamics system.Furthermore,by comparative research,the influence of wheelset flexibility and rotation on wheel-rail dynamic behavior are obtained,which is useful to the application scope of rigid and flexible wheelset models.展开更多
The SI system of units in rotational mechanics yields correct numerical results, but it produces physically incorrect units of measure in many cases. SI units also violate the principle of general covariance—the gene...The SI system of units in rotational mechanics yields correct numerical results, but it produces physically incorrect units of measure in many cases. SI units also violate the principle of general covariance—the general rule for defining continuous coordinates and units in mathematics and mathematical physics. After 30+ years of wrestling with these problems, the ultimate authority on units of measure has declared that Newton–meter and Joule are not equivalent in rotational mechanics, as they are in the rest of physics. This article proposes a simple modification to SI units called “Nonstandard International units” (“NI units”) until a better name is agreed upon. NI units yield correct numerical results and physically correct units of measure, and they satisfy the principle of general covariance. The main obstacle to the adoption of NI units is the consensus among users that the radius of rotation should have the unit meter because the radius can be measured with a ruler. NI units assigned to radius should have units meter/radian because the radius is a conversion factor between angular size and circumferential length, as in arclength = rθ. To manage the social consensus behind SI units, the author recommends retaining SI units as they are, and informing users who want correct units that NI units solve the technical problems of SI units.展开更多
Objective:To analyze the enduring rotational steadiness of AcrySof IQ Toric intraocular lens(IOL)in cataract patients suffering from myopia in a long-term study.Methods:A retrospective study was conducted on a case se...Objective:To analyze the enduring rotational steadiness of AcrySof IQ Toric intraocular lens(IOL)in cataract patients suffering from myopia in a long-term study.Methods:A retrospective study was conducted on a case series involving 78 patients.A total of 120 eyes with an axial length(AL)ranging from 24-30 mm and corneal astigmatism≥1.50 D underwent implantation of AcrySof IQ Toric IOL guided by the version navigation system.The eyes were divided into two groups based on AL.Group A included 60 eyes with high myopia(AL≥26 mm),while Group B consisted of eyes with low to moderate myopia(24 mm≤AL<26 mm).Data on the preoperative AL were collected.Measurements were taken for residual astigmatism,the best corrected visual acuity(BCDVA),corneal astigmatism,and IOL rotation occurring between 24-and 48-months post-surgery.The percentage of eyes with an IOL rotation of under 5°and 10°was analyzed.Results:The mean length of follow-up times was recorded as 34.27±4.98,and the average rotation was 2.73±1.29°.Group A exhibited a slightly higher average rotation of 2.87±1.31°,compared to the rotation of 2.59±1.27°observed in Group B.At both the 24-36 month and 26-48 month post-operation marks,the degree of IOL rotation did not show a statistically significant difference between the two groups,with none of the patients experiencing a rotation exceeding 10°(P>0.05).The percentage of rotation degrees under 5°was recorded as 98.22%.After the procedure,the BCDVA was 0.1322±0.03 LogMAR.There was a substantial increase in theχvalue after the operation as compared to the pre-operativeχ^(2) value(χ^(2)=76.79).The standard deviation of preoperative corneal astigmatism was statistically significant(P<0.05)at 2.17±1.08 D.Following the surgical procedure,the remaining astigmatism was measured at 0.41±0.26 D.The data showed a notable gap in statistical significance(t=4.281,P<0.05).Conclusion:The AcrySof Toric IOL was a reliable solution for managing corneal astigmatism in cataract patients with myopia,demonstrating excellent long-term rotational stability.展开更多
In a second-order r-mode theory, Sa and Tome found that the r-mode oscillation in neutron stars (NSs) could induce stellar differential rotation, which naturally leads to a saturated state of the oscillation. Based ...In a second-order r-mode theory, Sa and Tome found that the r-mode oscillation in neutron stars (NSs) could induce stellar differential rotation, which naturally leads to a saturated state of the oscillation. Based on a consideration of the coupling of the r-modes and the stellar spin and thermal evolution, we carefully investigate the influences of the differential rotation on the long-term evolution of isolated NSs and NSs in low-mass X-ray binaries, where the viscous damping of the r-modes and its resultant effects are taken into account. The numerical results show that, for both kinds of NSs, the differential rotation can significantly prolong the duration of the r-modes. As a result, the stars can keep nearly a constant temperature and constant angular velocity for over a thousand years. Moreover, the persistent radiation of a quasi-monochromatic gravitational wave would also be predicted due to the long-term steady r-mode oscillation and stellar rotation. This increases the detectability of gravitational waves from both young isolated and old accreting NSs.展开更多
In our previous work, we developed a model to study the effects of rotation and/or tidal distortions on anharmonic radial oscillations and hence on the radial velocity curves of the polytropic models of pulsating vari...In our previous work, we developed a model to study the effects of rotation and/or tidal distortions on anharmonic radial oscillations and hence on the radial velocity curves of the polytropic models of pulsating variable stars.We considered the first three modes(fundamental and the next two higher modes) for the polytropic models of index 1.5 and 3.0 in that work.In the present paper, we are further extending our previous work to study the effect of the interaction of various modes on anharmonic radial oscillations and hence on radial velocity curves of the rotationally and/or tidally distorted polytropic models of pulsating variable stars.For this purpose, we have considered the following cases:(i) fundamental mode(ii) fundamental and the first mode,(iii) fundamental and the next two modes and finally(iv) fundamental and the next three higher modes of pulsation in our study.The objective of this paper is also to investigate whether the interaction of various modes affects the results of our previous study or not.The results of this study show that the interaction of the fundamental mode with higher modes appreciably changes the shape of the radial velocity curve of rotationally distorted and rotationally and tidally distorted polytropic models of pulsating variable stars.展开更多
文摘In the present paper, the establishment of a systematic multi-barycenter mechanics is based on the multi-particle mechanics. The new theory perfects the basic theoretical system of classical mechanics, which finds the law of mutual interaction between particle groups, reveals the limitations of Newton’s third law, discovers the principle of the intrinsic relationship between gravity and tidal force, reasonably interprets the origin and change laws for the rotation angular momentum of galaxies and stars and so on. By applying new theory, the multi-body problem can be transformed into a special two-body problem and for which an approximate solution method is proposed, the motion law of each particle can be roughly obtained.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences, grant No. XDB41000000the National Natural Science Foundation of China (No. 11973082)the National Key R&D Program of China, grant Nos. 2021YFA1600400/2021YFA1600402.
文摘The tidal interactions of planets affect the stellar evolutionary status and the constraint of their physical parameters by gyrochronology.In this work,we incorporate the tidal interaction and magnetic braking of the stellar wind into MESA and calculate a large grid of 25,000 models,covering planets with masses of 0.1–13.0MJ with different orbital distances that orbit late-type stars of different metallicities.We also explore the effect of different stellar initial rotations on the tidal interactions.Our results show that in the case of tidal inward migration,the stellar rotation periods are always lower than that of the star without planet before the planet is engulfed and the difference in the rotation period of its host star always increases with time.After the planet is engulfed,the stellar rotation periods are still lower than that of star without planet,but the difference of periods can be quickly eliminated if the star has a thick convective envelope(smaller mass and larger metallicity),regardless of the mass of the planet and the initial rotation period of the star.In the case of stars with thinner convective envelopes(larger mass and smaller metallicity),the stars will be spun up and remain the faster rotation in a long time.Meanwhile,the planet is easily swallowed and the period differences are large if the initial rotation period of its host star is higher.Finally,we also study the evolution of WASP-19 and estimate the range of tidal quality parameter Q_(*)^(')=(4.6±0.9)×10^(6)and the initial semimajor axis as(0.035±0.004)au.
基金Project supported by the National Science and Technology Major Project of China (No. 2017-V-0009)the National Natural Science Foundation of China (Nos. 12032015 and 12121002)the National Funding Program for Postdoctoral Researchers of China (No. GZC20231586)。
文摘Blade rubbing faults cause detrimental impact on the operation of aeroengines. Most of the existing studies on blade rubbing in the shaft-disk-blade-casing(SDBC) system have overlooked the elastic deformation of the blade, while some only consider the whirl of the rotor, neglecting its spin. To address these limitations, this paper proposes a dynamic model with large rotation for the SDBC system. The model incorporates the spin and whirl of the rotor, enabling the realistic reproduction of multiblade rubbing faults. To verify the accuracy of the SDBC model with large rotation and demonstrate its capability to effectively consider the rotational effects such as the centrifugal stiffening and gyroscopic effects, the natural characteristics and dynamic responses of the proposed model are compared with those obtained from reported research and experimental results. Furthermore, the effects of the rotating speed, contact stiffness,and blade number on the dynamic characteristics of the SDBC system with multi-blade rubbing are investigated. The results indicate that the phase angle between the rotor deflection and the unbalance excitation force increases with the increasing rotating speed,which significantly influences the rubbing penetration of each blade. The natural frequency of the SDBC system with rubbing constrain can be observed in the acceleration response of the casing and the torsional response of the shaft, and the frequency is related to the contact stiffness. Moreover, the vibration amplitude increases significantly with the product of the blade number under rubbing, and the rotating frequency approaches the natural frequency of the SDBC system. The proposed model can provide valuable insight for the fault diagnosis of rubbing in bladed rotating machinery.
基金supported by the National SKA Program of China(Nos.2020SKA0120300,2020SKA0120100)the Outstanding Young and Middle-aged Science and Technology Innovation Teams from Hubei colleges and universities(No.T2021026)the Young Top-notch Talent Cultivation Program of Hubei Province,and the Key Laboratory Opening Fund(MOE)of China(grant No.QLPL2021P01)。
文摘Strangeon stars,which are proposed to describe the nature of pulsar-like compact stars,have passed various observational tests.The maximum mass of a non-rotating strangeon star could be high,which implies that the remnants of binary strangeon star mergers could even be long-lived massive strangeon stars.We study rigidly rotating strangeon stars in the slowly rotating approximation,using the Lennard-Jones model for the equation of state.Rotation can significantly increase the maximum mass of strangeon stars with unchanged baryon numbers,enlarging the mass-range of long-lived strangeon stars.During spin-down after merger,the decrease of radius of the remnant will lead to the release of gravitational energy.Taking into account the efficiency of converting the gravitational energy luminosity to the observed X-ray luminosity,we find that the gravitational energy could provide an alternative energy source for the plateau emission of X-ray afterglow.The fitting results of X-ray plateau emission of some short gamma-ray bursts suggest that the magnetic dipole field strength of the remnants can be much smaller than that of expected when the plateau emission is powered only by spin-down luminosity of magnetars.
基金support from the China Manned Space Project Nos. CMS-CSST-2021-B03,CMS-CSST-2021-A08, and________the National Natural Science Foundation of China under grant No. 12233013,12073090+8 种基金the Natural Science Foundation of Guangdong Province under grant No. 2022A1515010732grant support provided by Proyecto Fondecyt Iniciación No. 11220340ANID Concurso de Fomento a la Vinculación Internacional para Instituciones de Investigación Regionales (Modalidad corta duración) Proyecto No. FOVI210020Joint Committee ESO-Government of Chile 2021 (ORP 023/2021)Becas Santander Movilidad Internacional Profesores 2022, Banco Santander Chilesupport from the National Natural Science Foundation of China through grant 21BAA00619the one-hundred-talent project of Sun Yat-sen Universitythe Fundamental Research Funds for the Central UniversitiesSun Yat-sen University (22hytd09)。
文摘During the long term evolution of globular clusters(GCs), some member stars are lost to the field. The recently found nitrogen-rich(N-rich) metal-poor field stars are promising candidates of these GC escapees, since N enhancement is the fingerprint of chemically enhanced populations in GCs. In this work, we discuss the possibility of identifying N-rich metal-poor field stars with the upcoming Chinese Space Station Telescope(CSST). We focus on the main survey camera with NUV, u, g, r, i, z, y filters and slitless spectrograph with a resolution about 200.The combination of UV sensitive equipment and prominent N-related molecular lines in the UV band bodes well for the identification: the color–color diagram of(u-g) versus(g-r) is capable of separating N-rich field stars from normal halo stars, if metallicity can be estimated without using the information on u-band photometry.Besides, the synthetic spectra show that a signal-to-noise ratio of 10 is sufficient to identify N-rich field stars. In the near future, a large sample of N-rich field stars found by CSST, combined with state-of-the-art N-body simulations will be crucial to deciphering GC-Galaxy co-evolution.
基金supported by the National SKA Program of China(2020SKA0120100)supported by NSFC grant No.12203017。
文摘Can pulsar-like compact objects release further huge free energy besides the kinematic energy of rotation?This is actually relevant to the equation of state of cold supra-nuclear matter,which is still under hot debate.Enormous energy is surely needed to understand various observations,such asγ-ray bursts,fast radio bursts and softγ-ray repeaters.In this paper,the elastic/gravitational free energy of solid strangeon stars is revisited for strangeon stars,with two anisotropic models to calculate in general relativity.It is found that huge free energy(>10^(46)erg)could be released via starquakes,given an extremely small anisotropy((p_(t)-p_(r))/p_(r)~10^(-4),with pt/pr the tangential/radial pressure),implying that pulsar-like stars could have great potential of free energy release without extremely strong magnetic fields in the solid strangeon star model.
基金support from the Key Technology Research and Development Program of Shandong Province(Project No.2019GGX102060).
文摘This study investigated the formation mechanism of new grains due to twin–twin intersections in a coarse-grained Mg–6Al–3Sn–2Zn alloy during different strain rates of an isothermal compression.The results of electron backscattered diffraction investigations showed that the activated twins were primarily{1012}tension twins,and 60°<1010>boundaries formed due to twin–twin intersections under different strain rates.Isolated twin variants with 60°<1010>boundaries transformed into new grains through lattice rotations at a low strain rate(0.01 s^(−1)).At a high strain rate(10 s^(−1)),the regions surrounded by subgrain boundaries through high-density dislocation arrangement and the 60°<1010>boundaries transformed into new grains via dynamic recrystallization.
文摘The Gaia DR3 parallax approach was used to estimate the absolute parameters of 2375δScuti stars from the ASAS catalog.The selected stars have a variety of observational characteristics,with a higher than 80%probability of beingδScuti stars.We have displayed all the stars in the Hertzsprung-Russell diagram along with theδScuti instability strip,the Zero Age Main Sequence and the Terminal Age Main Sequence.Then,we determined which fundamental and overtone modes each star belongs to using pulsation constant(Q)calculations.In addition,we evaluated the parameters in the Q calculation equation using three machine learning methods,which showed that surface gravity and temperature have the greatest effect on its calculation.The Period-Luminosity(P-L)relationship of theδScuti stars was also revisited.Eventually,using least squares linear regression,we made four linear fits for fundamental and overtone modes and updated their relationships.
基金Shanxi Scholarship Council of China(2022-141)Fundamental Research Program of Shanxi Province(202203021211096).
文摘Recent research in cross-domain intelligence fault diagnosis of machinery still has some problems,such as relatively ideal speed conditions and sample conditions.In engineering practice,the rotational speed of the machine is often transient and time-varying,which makes the sample annotation increasingly expensive.Meanwhile,the number of samples collected from different health states is often unbalanced.To deal with the above challenges,a complementary-label(CL)adversarial domain adaptation fault diagnosis network(CLADAN)is proposed under time-varying rotational speed and weakly-supervised conditions.In the weakly supervised learning condition,machine prior information is used for sample annotation via cost-friendly complementary label learning.A diagnosticmodel learning strategywith discretized category probabilities is designed to avoidmulti-peak distribution of prediction results.In adversarial training process,we developed virtual adversarial regularization(VAR)strategy,which further enhances the robustness of the model by adding adversarial perturbations in the target domain.Comparative experiments on two case studies validated the superior performance of the proposed method.
基金the National Natural Science Foundation of China(NSFC)through grants 12003022,12373035,12233009 and 12173047support from the Youth Innovation Promotion Association of the CAS(grant No.2022055)。
文摘Open clusters are the basic building blocks that serve as a laboratory for the study of young stellar populations in the Milky Way.Variable stars in open clusters provide a unique way to accurately probe the internal structure,temporal and dynamical evolutionary stages of individual stars and the host cluster.The most powerful tool for such studies is time-domain photometric observations.This paper follows the route of our previous work,concentrating on a photometric search for variable stars in NGC 884.The target cluster is the companion of NGC869,forming the well-known double cluster system that is gravitationally bound.From the observation run in 2016 November,a total of 9247 B-band CCD images and 8218Ⅴ-band CCD images were obtained.We detected a total of 15 stars with variability in visual brightness,including five Be stars,three eclipsing binaries,and seven of unknown types.Two new variable stars were discovered in this work.We also compared the variable star content of NGC 884 with its companion NGC 869.
基金financially supported by Science and Technology Major Project of Changsha,China(No.kh2401034)the Fundamental Research Funds for the Central Universities of Central South University(No.CX20230182)the National Key Research and Development Project of China(No.2019YFA0709002)。
文摘Additive friction stir deposition(AFSD)is a novel structural repair and manufacturing technology has become a research hotspot at home and abroad in the past five years.In this work,the microstructural evolution and mechanical performance of the Al-Mg-Si alloy plate repaired by the preheating-assisted AFSD process were investigated.To evaluate the tool rotation speed and substrate preheating for repair quality,the AFSD technique was used to additively repair 5 mm depth blind holes on 6061 aluminum alloy substrates.The results showed that preheat-assisted AFSD repair significantly improved joint bonding and joint strength compared to the control non-preheat substrate condition.Moreover,increasing rotation speed was also beneficial to improve the metallurgical bonding of the interface and avoid volume defects.Under preheating conditions,the UTS and elongation were positively correlated with rotation speed.Under the process parameters of preheated substrate and tool rotation speed of 1000 r/min,defect-free specimens could be obtained accompanied by tensile fracture occurring in the substrate rather than the repaired zone.The UTS and elongation reached the maximum values of 164.2MPa and 13.4%,which are equivalent to 99.4%and 140%of the heated substrate,respectively.
文摘A concept of ensemble averaged stellar reactors is developed to study the dynamics of processes occurring in stars, allocated in the ~200 pc solar neighborhood. According to the effective temperature value, four stellar classes are identified, for which the correlation coefficients and standard deviation are counted. The theory of the buoyancy terrestial elements is generalized to stellar systems. It was suggested that stars are over-heated due to the shift parameters of the nuclear processes occurring inside the stars, which leads to the synthesis of transuranium elements until the achievement of a critical nuclear mass and star explosion. The heavy transuranium elements sink downward and are concentrated in the stellar depth layers. The physical explanation of the existence of the critical Chandrasekhar star limit has been offered. Based on the spatial analysis of overheated stars, it was suggested that the withdrawal of the stellar reactor from the equilibrium state is a consequence of extragalactic compression inside the galaxy arm due to the arm spirality (not to be confused with the spirality of the galaxy itself).
文摘Purpose: To present a protocol of a dual-field rotational (DFR) total skin electron therapy (TSET) and to provide an assessment of clinical implementation, dosimetry properties, and skin dose evaluation. Methods and Materials: The DFR-TSET combined the Stanford 6-field and McGill rotational methods. Dual 6 MeV electron beams in high dose total skin electron mode were used for DFR-TSET on a commercial linac. Beam profiles and dosimetric properties were measured using solid phantoms. The dose rate at expanded source-to-surface distance (SSD) was a combination of static rate and rotational rate. In vivo dosimetry of patient skin was performed on patients’ skin using film, metal oxide semiconductor field-effect transistors (MOSFET), and optically stimulated luminescent dosimeters (OSLD). Results: Dual field rotational total skin electron therapy exhibited good (≤±10%) uniformity in the beam profiles in the vertical direction at an extended SSD of 332 cm with a gantry angulation of ±20˚ deviated from the horizontal direction. In-vivo measurements confirmed acceptable uniformity of the patients’ total body surfaces and revealed anatomically self-blocked or shielded areas where underdosing occurred. Conclusions: The clinical implementation of DFR-TSET effectively utilizes the special mode on a linac. This technique provides short beam-on times, uniform dose distribution, large treatment field, and reduced dose of x-ray contamination to the patients. In-vivo measurements indicate satisfactory delivery and dose uniformity of the prescribed dose. Electron boost fields are recommended at normal SSDs to address underdosed areas.
基金supported by the National MCF Energy R&D Program of China(Nos.2019YFE03090400 and 2019YFE03030004)National Natural Science Foundation of China(Nos.12375222 and 11775154)National Key R&D Program of China(Nos.2017YFE0301203 and 2017YFE0301101)。
文摘The effects of equilibrium toroidal rotation during edge-localized mode(ELM)mitigated by resonant magnetic perturbation(RMP)are studied with the experimental equilibria of the EAST tokamak based on the four-field model in the BOUT++code.As the two main parameters to determine the toroidal rotation profiles,the rotation shear and magnitudes were separately scanned to investigate their roles in the impact of RMPs on peeling-ballooning(P-B)modes.On one hand,the results show that strong toroidal rotation shear is favorable for the enhancement of the self-generated E×B shearing rate<ω_(E×B)>with RMPs,leading to significant ELM mitigation with RMP in the stronger toroidal rotation shear region.On the other hand,toroidal rotation magnitudes may affect ELM mitigation by changing the penetration of the RMPs,more precisely the resonant components.RMPs can lead to a reduction in the pedestal energy loss by enhancing the multimode coupling in the turbulence transport phase.The shielding effects on RMPs increase with the toroidal rotation magnitude,leading to the enhancement of the multimode coupling with RMPs to be significantly weakened.Hence,the reduction in pedestal energy loss by RMPs decreased with the rotation magnitude.In brief,the results show that toroidal rotation plays a dual role in ELM mitigation with RMP by changing the shielding effects of plasma by rotation magnitude and affecting<ω_(E×B)>by rotation shear.In the high toroidal rotation region,toroidal rotation shear is usually strong and hence plays a dominant role in the influence of RMP on P-B modes,whereas in the low rotation region,toroidal rotation shear is weak and has negligible impact on P-B modes,and the rotation magnitude plays a dominant role in the influence of RMPs on the P-B modes by changing the field penetration.Therefore,the dual role of toroidal rotation leads to stronger ELM mitigation with RMP,which may be achieved both in the low toroidal rotation region and the relatively high rotation region that has strong rotational shear.
基金supported by the National Natural Science Foundation of China(NSFC.Grant Nos.12288102 and 12333008)the National Key R&D Program of China(No.2021YFA1600403)+5 种基金support from the Yunnan Ten Thousand Talents Plan-Young&Elite Talents Projectthe CAS“Light of West China”Programsupport from International Centre of Supernovae,Yunnan Key Laboratory(No.202302AN360001)the Yunnan Revitalization Talent Support Program-Science&Technology Champion Project(NO.202305AB350003)Yunnan Fundamental Research Projects(NOs.202401BC070007,202201BC070003)the science research grants from the China Manned Space Project。
文摘The origin of intermediate helium (He)-rich hot subdwarfs is still unclear.Previous studies have suggested that some surviving Type Ia supernovae (SNe Ia) companions from the white dwarf+main-sequence (WD+MS)channel may contribute to the intermediate He-rich hot subdwarfs.However,previous studies ignored the impact of atomic diffusion on the post-explosion evolution of surviving companion stars of SNe Ia,leading to the aspect that they could not explain the observed surface He abundance of intermediate He-rich hot subdwarfs.In this work,by taking the atomic diffusion and stellar wind into account,we trace the surviving companions of SNe Ia from the WD+MS channel using the one-dimensional stellar evolution code MESA until they evolve into hot subdwarfs.We find that the surface He-abundances of our surviving companion models during their core He-burning phases are in a range of-1■log(N_(He) N_(H))■0,which are consistent with those observed in intermediate He-rich hot subdwarfs.This seems to further support the notion that it is possible for surviving companions of SNe Ia in the WD+MS channel to form some intermediate He-rich hot subdwarfs.
基金China National Railway Group Science and Technology Program(N2022J009)China Academy of Railway Sciences Group Co.,Ltd.Program(2021YJ036).
文摘Purpose-Under the high-speed operating conditions,the effects of wheelset elastic deformation on the wheel rail dynamic forces will become more notable compared to the low-speed condition.In order to meet different analysis requirements and selecting appropriate models to analyzing the wheel rail interaction,it is crucial to understand the influence of wheelset flexibility on the wheel-rail dynamics under different speeds and track excitations condition.Design/methodology/approach-The wheel rail contact points solving method and vehicle dynamics equations considering wheelset flexibility in the trajectory body coordinate system were investigated in this paper.As for the wheel-rail contact forces,which is a particular force element in vehicle multibody system,a method for calculating the Jacobian matrix of the wheel-rail contact force is proposed to better couple the wheel-rail contact force calculation with the vehicle dynamics response calculation.Based on the flexible wheelset modeling approach in this paper,two vehicle dynamic models considering the wheelset as both elastic and rigid bodies are established,two kinds of track excitations,namely normal measured track irregularities and short-wave irregularities are used,wheel-rail geometric contact characteristic and wheel-rail contact forces in both time and frequency domains are compared with the two models in order to study the influence of flexible wheelset rotation effect on wheel rail contact force.Findings-Under normal track irregularity excitations,the amplitudes of vertical,longitudinal and lateral forces computed by the flexible wheelset model are smaller than those of the rigid wheelset model,and the virtual penetration and equivalent contact patch are also slightly smaller.For the flexible wheelset model,the wheel rail longitudinal and lateral creepages will also decrease.The higher the vehicle speed,the larger the differences in wheel-rail forces computed by the flexible and rigid wheelset model.Under track short-wave irregularity excitations,the vertical force amplitude computed by the flexible wheelset is also smaller than that of the rigid wheelset.However,unlike the excitation case of measured track irregularity,under short-wave excitations,for the speed within the range of 200 to 350 km/h,the difference in the amplitude of the vertical force between the flexible and rigid wheelset models gradually decreases as the speed increase.This is partly due to the contribution of wheelset's elastic vibration under short-wave excitations.For low-frequency wheel-rail force analysis problems at speeds of 350 km/h and above,as well as high-frequency wheel-rail interaction analysis problems under various speed conditions,the flexible wheelset model will give results agrees better with the reality.Originality/value-This study provides reference for the modeling method of the flexible wheelset and the coupling method of wheel-rail contact force to the vehicle multibody dynamics system.Furthermore,by comparative research,the influence of wheelset flexibility and rotation on wheel-rail dynamic behavior are obtained,which is useful to the application scope of rigid and flexible wheelset models.
文摘The SI system of units in rotational mechanics yields correct numerical results, but it produces physically incorrect units of measure in many cases. SI units also violate the principle of general covariance—the general rule for defining continuous coordinates and units in mathematics and mathematical physics. After 30+ years of wrestling with these problems, the ultimate authority on units of measure has declared that Newton–meter and Joule are not equivalent in rotational mechanics, as they are in the rest of physics. This article proposes a simple modification to SI units called “Nonstandard International units” (“NI units”) until a better name is agreed upon. NI units yield correct numerical results and physically correct units of measure, and they satisfy the principle of general covariance. The main obstacle to the adoption of NI units is the consensus among users that the radius of rotation should have the unit meter because the radius can be measured with a ruler. NI units assigned to radius should have units meter/radian because the radius is a conversion factor between angular size and circumferential length, as in arclength = rθ. To manage the social consensus behind SI units, the author recommends retaining SI units as they are, and informing users who want correct units that NI units solve the technical problems of SI units.
基金This study was funded by a research grant from Alcon(IIT#68022037)Subject of Medical and Health Research in Heilongjiang Province(20230707020332).
文摘Objective:To analyze the enduring rotational steadiness of AcrySof IQ Toric intraocular lens(IOL)in cataract patients suffering from myopia in a long-term study.Methods:A retrospective study was conducted on a case series involving 78 patients.A total of 120 eyes with an axial length(AL)ranging from 24-30 mm and corneal astigmatism≥1.50 D underwent implantation of AcrySof IQ Toric IOL guided by the version navigation system.The eyes were divided into two groups based on AL.Group A included 60 eyes with high myopia(AL≥26 mm),while Group B consisted of eyes with low to moderate myopia(24 mm≤AL<26 mm).Data on the preoperative AL were collected.Measurements were taken for residual astigmatism,the best corrected visual acuity(BCDVA),corneal astigmatism,and IOL rotation occurring between 24-and 48-months post-surgery.The percentage of eyes with an IOL rotation of under 5°and 10°was analyzed.Results:The mean length of follow-up times was recorded as 34.27±4.98,and the average rotation was 2.73±1.29°.Group A exhibited a slightly higher average rotation of 2.87±1.31°,compared to the rotation of 2.59±1.27°observed in Group B.At both the 24-36 month and 26-48 month post-operation marks,the degree of IOL rotation did not show a statistically significant difference between the two groups,with none of the patients experiencing a rotation exceeding 10°(P>0.05).The percentage of rotation degrees under 5°was recorded as 98.22%.After the procedure,the BCDVA was 0.1322±0.03 LogMAR.There was a substantial increase in theχvalue after the operation as compared to the pre-operativeχ^(2) value(χ^(2)=76.79).The standard deviation of preoperative corneal astigmatism was statistically significant(P<0.05)at 2.17±1.08 D.Following the surgical procedure,the remaining astigmatism was measured at 0.41±0.26 D.The data showed a notable gap in statistical significance(t=4.281,P<0.05).Conclusion:The AcrySof Toric IOL was a reliable solution for managing corneal astigmatism in cataract patients with myopia,demonstrating excellent long-term rotational stability.
基金Supported by the National Natural Science Foundation of China(Grant Nos.10603002 and 10773004)
文摘In a second-order r-mode theory, Sa and Tome found that the r-mode oscillation in neutron stars (NSs) could induce stellar differential rotation, which naturally leads to a saturated state of the oscillation. Based on a consideration of the coupling of the r-modes and the stellar spin and thermal evolution, we carefully investigate the influences of the differential rotation on the long-term evolution of isolated NSs and NSs in low-mass X-ray binaries, where the viscous damping of the r-modes and its resultant effects are taken into account. The numerical results show that, for both kinds of NSs, the differential rotation can significantly prolong the duration of the r-modes. As a result, the stars can keep nearly a constant temperature and constant angular velocity for over a thousand years. Moreover, the persistent radiation of a quasi-monochromatic gravitational wave would also be predicted due to the long-term steady r-mode oscillation and stellar rotation. This increases the detectability of gravitational waves from both young isolated and old accreting NSs.
基金the Council of Scientific and Industrial Research (CSIR) for the financial support
文摘In our previous work, we developed a model to study the effects of rotation and/or tidal distortions on anharmonic radial oscillations and hence on the radial velocity curves of the polytropic models of pulsating variable stars.We considered the first three modes(fundamental and the next two higher modes) for the polytropic models of index 1.5 and 3.0 in that work.In the present paper, we are further extending our previous work to study the effect of the interaction of various modes on anharmonic radial oscillations and hence on radial velocity curves of the rotationally and/or tidally distorted polytropic models of pulsating variable stars.For this purpose, we have considered the following cases:(i) fundamental mode(ii) fundamental and the first mode,(iii) fundamental and the next two modes and finally(iv) fundamental and the next three higher modes of pulsation in our study.The objective of this paper is also to investigate whether the interaction of various modes affects the results of our previous study or not.The results of this study show that the interaction of the fundamental mode with higher modes appreciably changes the shape of the radial velocity curve of rotationally distorted and rotationally and tidally distorted polytropic models of pulsating variable stars.