Pulsations of Three Rapidly Oscillating Ap Stars TIC 96315731,TIC72392575,and TIC 318007796

We analyze the frequencies of three known roAp stars,TIC 96315731,TIC 72392575,and TIC 318007796,using the light curves from the Transiting Exoplanet Survey Satellite.For TIC 96315731,the rotational and pulsational frequencies are 0.1498360 day^(-1)and 165.2609 day^(-1),respectively.In the case of TIC 72392575,the rotational frequency is 0.25551 day^(-1).We detect a quintuplet of pulsation frequencies with a center frequency of135.9233 day^(-1),along with two signals within the second pair of rotational sidelobes of the quintuplet separated by the rotation frequency.These two signals may correspond to the frequencies of a dipole mode.In TIC318007796,the rotational and pulsational frequencies are 0.2475021 day^(-1),192.73995 day^(-1),and196.33065 day^(-1),respectively.Based on the oblique pulsator model,we calculate the rotation inclination(i)and magnetic obliquity angle(b)for the stars,which provide the geometry of the pulsation modes.Combining the phases of the frequency quintuplets,the pulsation amplitude and phase modulation curves,and the results of spherical harmonic decomposition,we conclude that the pulsation modes of frequency quintuplets in TIC96315731,TIC 72392575,and TIC 318007796 correspond to distorted dipole mode,distorted quadrupole mode,and distorted dipole mode,respectively.

The characteristics of Pi2 pulsations at Zhongshan Station ofAntarctica

In this paper Pi2 pulsations at Zhongshan Station of Antarctica are analyzed from October 1 - 31, 1996. Their characteristics e. g. occurrence frequency,frequency, and polarization are studied. The characteristics of Pi2 pulsations are summerized as follows: (1 ) Pi2 pulsations at Zhongshan Station usually take place from 2000 MLT to 0200 MLT; the main frequencies are between 6. 79 mHz and 13. 58mHZ; (2 ) Pi2 pulsations with low frequencies are dominent. The range of main frequencies becomes narrow at midnight; (3) The Polarization of Pi2 pulsations are almost linear; (4) About the orientation of major axes the NW-SE direction is dominent before 2200 MLT and NE-SW is dominent after 2200 MLT. The generation mechanism of Pi2 pulsations at Zhongshan Station is discussed theoretically.

Characteristics of Pc3 pulsations at Great Wall Station,Antarctica

In this paper Pc3 pulsations at Great Wall Station of Antarctica are analyzed statistically from August 16 to November 20,1990.The occurrence frequency,frequency and polarization are studied for Pc3 pulsation events.The mechanisms of excitation and propagation of Pc3 pulsations at Great Wall Station are discussed theoretically.

The characteristics of Pi2 pulsations at Great Wall Station,Antarctica

In this paper Pi2 pulsation events at Great Wall Station of Antarctica are analyzed from August 16,1990 to November 20,1990.Their main characteristics e. g.occurrence frequency, frequency,and polarizations are recognize. The mechanism of excitation for Pi2 pulsations at Great Wall Station is here discussed theoretically.

Vibration analysis of large bulb tubular pump house under pressure pulsations

A 3D finite element model of the Huaiyin third pumping station of the Eastern Route of the South-to-North Water Transfer is described in this paper. Two methods were used in the calculation and vibration analysis of the pumping station in both the time domain and the frequency domain. The pressure pulsation field of the whole flow passage was structured on the basis of pressure pulsations recorded at some locations of the physical model test. Dynamic time-history analysis of the pump house under pressure pulsations was carried out. At the same time, according to spectrum characteristics of the pressure pulsations at measuring points and results of free vibration characteristics analysis of the pump house, the spectrum analysis method of random vibration was used to calculate dynamic responses of the pump house. Results from both methods are consistent, which indicates that they are both reasonable. The results can be used for reference in anti-vibration safety evaluation of the Huaiyin third pumping station.

Propagation characteristics of the Pc3 frequency range pulsations in the cusp latitudes

Two induction magnetometers have been installed at Zhongshan Station and Davis Station, Antarctica respectively. We adopt with cross-spectral analysis technique to analyze the data of the two induction magnetometers, in June, September,December 1996 and March 1997. to investigate the Pc3 frequency range pulsation occurrence and propagation characteristics in the cusp latitudes. The results are summarized as following:At Zhongshan-Davis Stations, the Pc3 frequency range pulsations occur mainly around the local noon/ local magnetic noon and local magnetic midnight respectively. In daytime, the pulsations have a seasonal variation in amplitude, occurrence and temporal range, all of them are sma1lest in winter. But in nighttime, the pulsations have no such a variation. The pu1sation amplitude in nighttime is much larger than the one in daytime all oveI the year. The pulsation propagating direction is mainly western in daytime and irregularly in nighttime. It can be thought that the different sources of the pulsation and the ionospheric electric conductivity are mainly responsible for these characteristics.

Polarization characteristics of Pc3 pulsations at Zhongshan Station of Antarctica

In this paper the data of geomagnetic pulsations at Zhongshan Station from February 3 to Novernber 30 in 1996 are analyzed in ordcr to study polarization characteristics of Zhongshan Station Pc3 pulsations which comprises the cusp Pc3 pulsation and the nightside Pc3 pulsation. For the cusp Pc3 pulsation. the right-handed polarization is always dominant. But their orientation of major axes of polarizations changes with season, NW-SE is dominant in summer and NE-SW in winter. For the nightside Pc3 pulsation,the right-handed with NE-SW is always dominant before midnight. But the left-handed with the mixing orientation of major axes is dominant in summer and the NE-SW with the mixing polarization sense is dominant in winter after midnight. It means that the two types of Zongshan Station Pc3 pulsations have different sources.

Critical analysis of the ULF power depression as a possible Tohoku earthquake precursor

Among electromagnetic methods of short-term earthquake prediction,an approach is being actively developed based on the phenomenon of magnetic ultra-low-frequency(ULF)power depression occurring a few days before an earthquake.In particular,a nighttime geomagnetic power depression in the band 0.03-0.05 Hz was observed approximately 5 days before the catastrophic Tohoku 2011 earthquake.To verify the reliability of this method,we performed an extended analysis using data from magnetometer arrays JMA,MAGDAS,PWING,and INTERMAGNET.The selected stations included sites close to the epicenter(<300 km)and remote points(~10000 km).The band-integrated spectral power of nighttime magnetic noise decreased significantly from March 6-9,several days before the earthquake.However,such variations occur simultaneously not only at nearby stations but also at distant stations.During this event,the ULF power depression was caused by low global geomagnetic activity,as evidenced by the planetary index SME.Thus,the depression of geomagnetic ULF noise cannot be considered a reliable short-term precursor.

Multipoint observations of Pi2 pulsations and correlation with dynamic processes in the near-Earth magnetotail on March 18,2009

Simultaneous measurements from THEMIS spacecraft, GOES11 and ground stations （Canadian Array for Realtime Investiga tions of Magnetic Activity or CARISMA, and 210 magnetic meridian or MM） on March 18, 2009 allow the study of dynamic processes in the nearEarth magnetotail and corresponding Pi2 pulsations on the ground in great detail. Fast earthward flows along with traveling Alfv6n waves and fast mode waves in the Pi2 band were observed by three Time History of Events and Macroscale Interactions during Substorms （THEM/S） probes （P3, P4 and P5） in the nearEarth plasmasbeet. At the mid to highlatitude nightside, the CARISMA stations located near the foot points of the three probes recorded Pi2s with two periods, about 80 s after the earthward fast flows observed by the P4 probe. The longperiod Pi2 （140-150 s） belongs to the transient response Pi2 （TR Pi2）, since the travel time of the Alfv6n waves between the plasma sheet and CARISMA stations is very close to half the period of the longperiod Pi2. The shortperiod Pi2 （60-80 s） has the same period band as the perpendicular velocity of the fast flows, which indicates that it may relate to the inertial current caused by periodic braking of the earthward fast flows. The 210 MM stations located at the lowlatitude duskside also observed Pi2s with the same start time, waveform and frequency, about 120 s after the earthward fast flows. Strong poloidal oscillations are shown by GOES11 （23 MLT） and the compressional component （Bb） is highly correlated with H components of the 210 MM stations, whereas the other two components （Br and Be） are not. These results confirm that the lowlatitude Pi2s are generated by cavity mode resonance, which is driven by an impulsive broadband source in the nearEarth magnetotail.

Qualitative Analysis for Rheodynamic Model of Cardiac Pressure Pulsations

In this paper, we give a rigorous mathematical and complete parameter analysis for the rheodynamic model of cardiac and obtain the conditions and parameter region for global existence and uniqueness of limit cycle and the global bifurcation diagram of limit cycles. We also discuss the resonance phenomenons of the perturbed system.

Numerical study of flow and thermal characteristics of pulsed impinging jet on a dimpled surface

This research comprehensively investigates the flow and thermal characteristics of a pulsating impinging jet over a dimpled surface.It analyzes the impact of key parameters(e.g.,inlet velocity pulsation functions,pulsation frequency,amplitude,dimple pitch,dimple depth,Reynolds number)on flow patterns and heat transfer.Validated computational fluid dynamics and the Re-normalization group turbulence model are employed to accurately simulate complex turbulent flow behavior.Local and average heat transfer coefficients are calculated and compared to steady impingement cases,revealing the potential benefits of pulsation for heat transfer enhancement.The study also examines how pulsation-induced flow modulation and thermal mixing affect heat transfer mechanisms.Results indicate that combining fluctuating flow with a dimpled surface can improve heat transfer rates.In summary,increasing pulsation amplitude consistently enhances heat transfer,while the effect of frequency varies between impinging and wall jet zones.

Nonlinear dynamics of a circular curved cantilevered pipe conveying pulsating fluid based on the geometrically exact model

Due to the novel applications of flexible pipes conveying fluid in the field of soft robotics and biomedicine,the investigations on the mechanical responses of the pipes have attracted considerable attention.The fluid-structure interaction(FSI)between the pipe with a curved shape and the time-varying internal fluid flow brings a great challenge to the revelation of the dynamical behaviors of flexible pipes,especially when the pipe is highly flexible and usually undergoes large deformations.In this work,the geometrically exact model(GEM)for a curved cantilevered pipe conveying pulsating fluid is developed based on the extended Hamilton's principle.The stability of the curved pipe with three different subtended angles is examined with the consideration of steady fluid flow.Specific attention is concentrated on the large-deformation resonance of circular pipes conveying pulsating fluid,which is often encountered in practical engineering.By constructing bifurcation diagrams,oscillating shapes,phase portraits,time traces,and Poincarémaps,the dynamic responses of the curved pipe under various system parameters are revealed.The mean flow velocity of the pulsating fluid is chosen to be either subcritical or supercritical.The numerical results show that the curved pipe conveying pulsating fluid can exhibit rich dynamical behaviors,including periodic and quasi-periodic motions.It is also found that the preferred instability type of a cantilevered curved pipe conveying steady fluid is mainly in the flutter of the second mode.For a moderate value of the mass ratio,however,a third-mode flutter may occur,which is quite different from that of a straight pipe system.

Damping of Pressure Pulsations in Mobile Hydraulic Applications by the Use of Closed Cell Cellular Rubbers Integrated into a Vane Pump

The present study evaluates the potential of a bio-inspired pulsation damper in a vane pump used in mobile hydraulic ap- plications. Pressure pulsations caused by such positive displacement pumps can lead to malfunctions and noise in a hydraulic system. A common measure to reduce pressure pulsations is the integration of pressure pulsation dampers downstream of the pump. This type of damping measure can also be found in biology as e.g. in the human blood circulatory system. Such working principles found in living organisms offer a high potential for a biomimetic transfer into technical applications. The newly developed bio-inspired damper consists of cellular rubbers with non-linear viscoelastic material properties. In order to evaluate the new damping method, pressure pulsations were measured at two different back pressures and at a wide engine speed range of the vane pump. For further assessment, different setups, varying the stiffness of the cellular rubber materials and the damper volume, were tested. Within the tested back pressures, the pressure pulsations could be reduced by up to 40%. The developed integrated pulsation damper offers a high potential to dampen pressure pulsations of positive displacement pumps used in mobile hydraulic applications ooeratin~ below 10 bar.

Research Progress of LipiFlow Therapy for Meibomian Gland Dysfunction

Meibomian gland dysfunction(MGD)is a common ocular surface disease,and the pathogenesis of MGD is closely related to the alteration of meibomian gland morphology and(or)function.At present,the treatment strategy for MGD consists of physical therapy,artificial lubricants,topical and systemic antibiotics and antiinflammatory agents,topical steroids andΩ-3 dietary supplementation.Recently,the thermal pulsation system(LipiFlow)has been used clinically,which allows heat to be applied to the palpebral surfaces of the upper and lower eyelids directly over the meibomian glands,while simultaneously applying pulsatile pressure to the outer eyelid surfaces.Due to its specific design,the cornea and eyeball can successfully avoid the potential damage from overheating and improper expression,which will greatly improve the safety during the clinical application and patients'compliance.Studies have showed that the effectiveness of LipiFlow when treating MGD is at least as well as twice-daily lid warming and massage for 3 months,which displays a broad application prospect.At present,the application of LipiFlow in China has not been fully developed,and only some hospitals have experimental applications.This paper summarizes the research progress of LipiFlow treatment in MGD.

Propagation Dynamics of Forced Pulsating Waves for a Time Periodic Lotka-Volterra Cooperative System with Nonlocal Effects in Shifting Habitats

In this paper, we will concern the existence, asymptotic behaviors and stability of forced pulsating waves for a Lotka-Volterra cooperative system with nonlocal effects under shifting habitats. By using the alternatively-coupling upper-lower solution method, we establish the existence of forced pulsating waves, as long as the shifting speed falls in a finite interval where the endpoints are obtained from KPP-Fisher speeds. The asymptotic behaviors of the forced pulsating waves are derived. Finally, with proper initial, the stability of the forced pulsating waves is studied by the squeezing technique based on the comparison principle.

Effect of the volute tongue cut on pressure pulsations of a low specific speed centrifugal pump

The volute tongue,as the crucial component inducing rotor-stator interaction,is detrimental to unsteady pressure pulsations of centrifugal pumps.In the present paper,to investigate the effect of the volute tongue cut on pressure pulsations of a low specific speed centrifugal pump,three volute tongues are obtained through twice cuts,named cases 1,2,3.Twenty measuring points are evenly mounted on periphery of the volute casing to obtain unsteady pressure signals using high response transducers.Pressure amplitudes at the blade passing frequency fBPF and root mean square(rms)values in 0 Hz-500 Hz frequency band are applied to evaluate the cutting effect.Results show that pressure spectrum is significantly affected by the volute tongue cut,especially for the component at fBPF.For different measuring points,influences of the volute tongue cut on three cases are not identical.From nns values,it is evident that cutting the volute tongue will lead to pressure energy increasing for most of the concerned measuring points,especially for the points at the far away region from the volute tongue.Finally,from comparison with the original shape case 1,the averaged increment of the twenty points is more than 20%.So it is concluded that for this type centrifugal pump,cutting the volute tongue is not reasonable considering low pressure pulsation requirement.

Pulsation Analysis of High-AmplitudeδScuti Stars with TESS

In this work,the pulsation analysis is performed on 83 high-amplitudeδScuti stars(HADS),which have been observed by the Transiting Exoplanet Survey Satellite.The results show that 49 of these HADS show single-mode pulsation,27 of them show radial double-modes pulsation(in which 22 of them pulsate with the fundamental and first overtone modes and five of them pulsate with the first and second overtone modes),and seven of them show radial triple-modes pulsation(three of which are newly confirmed triple-mode HADS).The histogram of the fundamental periods and the ratios between the fundamental and first overtone periods show bimodal structures,which might be caused by the stellar evolution in this specific phase.Most of the radial triple-mode HADS have a fundamental amplitude of 41-54 mmag,and 50%of them have similar amplitudes of the fundamental and first overtone pulsation modes.All these hints require further confirmation not only in observations with more HADS samples,but also in theoretical models with suitable treatments of stellar evolution and pulsation.

材料特性对输送脉动流体的粘弹性轴向功能梯度管非线性动力行为的影响

The nonlinear dynamic behaviors of viscoelastic axially functionally graded material(AFG)pipes conveying pulsating internal flow are very complex.And the dynamic behavior will induce the failure of the pipes,and research of vibration and stability of pipes becomes a major concern.Considering that the elastic modulus,density,and coefficient of viscoelastic damping of the pipe material vary along the axial direction,the transverse vibration equation of the viscoelastic AFG pipe conveying pulsating fluid is established based on the Euler-Bernoulli beam theory.The generalized integral transform technique(GITT)is used to transform the governing fourth-order partial differential equation into a nonlinear system of fourth-order ordinary differential equations in time.The time domain diagram,phase portraits,Poincarémap and power spectra diagram at different dimensionless pulsation frequencies,are discussed in detail,showing the characteristics of chaotic,periodic,and quasi-periodic motion.The results show that the distributions of the elastic modulus,density,and coefficient of viscoelastic damping have significant effects on the nonlinear dynamic behavior of the viscoelastic AFG pipes.With the increase of the material property coefficient k,the transition between chaotic,periodic,and quasi-periodic motion occurs,especially in the high-frequency region of the flow pulsation.

Analysis of periodic pulsating nanofluid flow and heat transfer through a parallel-plate channel in the presence of magnetic field

In this paper,we focus on the two-dimensional pulsating nanofluid flow through a parallel-plate channel in the presence of a magnetic field.The pulsating flow is produced by an applied pressure gradient that fluctuates with a small amplitude.A kind of proper transformation is used so that the governing equations describing the momentum and thermal energy are reduced to a set of non-dimensional equations.The analytical expressions of the pulsating velocity,temperature,and Nusselt number of nanofluids are obtained by the perturbation technique.In the present study,the effects of the Cu-H2O and Al_(2)O_(3)-H2O nanofluids on the flow and heat transfer in pulsating flow are compared and analyzed.The results show that the convective heat transfer effect of Cu-H2O nanofluids is better than that of Al_(2)O_(3)-H2O nanofluids.Also,the effects of the Hartmann number and pulsation amplitude on the velocity,temperature,and Nusselt number are examined and discussed in detail.The present work indicates that increasing the Hartmann number and pulsation amplitude can enhance the heat transfer of the pulsating flow.In addition,selecting an optimal pulsation frequency can maximize the convective heat transfer of the pulsating flow.Therefore,improved understanding of these fundamental mechanisms is conducive to the optimal design of thermal systems.

Comprehensive analysis of pure-quartic soliton dynamics in a passively mode-locked fiber laser

The understanding of soliton dynamics promotes the development of ultrafast laser technology. High-energy purequartic solitons(PQSs) have gradually become a hotspot in recent years. Herein, we numerically study the influence of the gain bandwidth, saturation power, small-signal gain, and output coupler on PQS dynamics in passively mode-locked fiber lasers. The results show that the above four parameters can affect PQS dynamics. Pulsating PQSs occur as we alter the other three parameters when the gain bandwidth is 50 nm. Meanwhile, PQSs evolve from pulsating to erupting and then to splitting as the other three parameters are altered when the gain bandwidth is 10 nm, which can be attributed to the existence of the spectral filtering effect and intra-cavity fourth-order dispersion. These findings provide new insights into PQS dynamics in passively mode-locked fiber lasers.