RESEARCH & DESIGN OF 60 kW SOFT-SWITCHING PLASMA CONVERTER

A novel 60 kW plasma converter with full range soft-switch by utilizing magnetizing inductance, leakage inductance and distributed inductance is introduced. The current injection phase-shifting technique is introduced into the research of soft-switching plasma converter successfully. The magnetic bias of transformer and the protection of switching parts are solved. The tests state that the power supply has excellent characteristics and higher efficiency and can meet the demand of large power plasma process well.

Tread Wear and Footprint Geometrical Characters of Truck Bus Radial Tires

Wear and mileage performance are the foremost performances for truck bus radial (TBR) tires. There are a lot of researches about the tire wear performance as well as the contact patch phenomenon by using finite element analysis (FEA) method or testing. But there is little published data on the correlations between the footprint geometry and the tread wear performance of tires. In this paper, an experiment on tire-ground performance of TBR tires is carried out by using Tekscan. The real-time changes of contact-area pressure distribution that occurred during the process of continuous load and unload are recorded. Three types of tires that act differently in behavior under normal usage are analyzed. A new method of researching in tire tread wear, which focuses on the geometrical characters of the footprint, is put forward. The experimental results of the three tires are described by using footprint geometrical characters. On the basis of studying the changing laws of footprint geometrical characters during the loading process and considering consumer survey and factory feedback information, the correlations between the geometrical character of footprints and tread destruction form are built. The analyzed results show that a greater contact area coefficient and a steady coefficient of contact result in a better wear performance for TBR tires. The footprint-shape coefficient changing laws in the process of loading are found to have a very good coincidence with the tread wear of the three types of tires. Tires with a smaller footprint-shape coefficient are likely to have an average tread wear while avoiding the shoulder wear first. The proposed research provides a new solution to predict tire-ground performance at the point of footprint and several useful references for improving tire design.

Principle and Control of Active Engine Mount Based on Magnetostrictive Actuator

Engine mount system affects the automobile NVH performance.Active mounts would achieve excellent vibration isolation and relative displacement control performance in a broad frequency bandwidth by outputting controlled force to the mounting system.The actuator and control method of the active mounts determine the system performance.In this paper,an active mount based on the smart material,i.e.,Terfenol-D rod,is proposed,which mainly includes three parts:rubber spring,magnetostrictive actuator(MA),and hydraulic amplification mechanism(HAM).Dynamic model of the active mount is correspondingly established.A state feedback control method based on x-LMS(Least-Mean-Square)algorithm is proposed as well.Specifically,with the consideration of the unmeasurable state parameters in the active mounting system,an x-LMS state feedback controller with the system state as the reference signal is constructed by employing Sage-Husa Kalman filter to realize the state estimation of the active mounting system.Then a detailed analysis of the proposed control method is conducted,with deriving iterative formula of tap-weight vector.Sequentially,the problem of the dependence on the excitation signal in the x-LMS algorithm is addressed.The feasibility and capability of the proposed control method are verified and evaluated by simulation of a two-degree-offreedom active mounting system.

Unripe Fruit Extracts of <i>Mangifera indica L.</i>Protect against AGEs Formation, Melanogenesis and UVA-Induced Cell Damage

In this study, we explored the effects of unripe fruit extracts of Mangifera indica L. on the anti-aging activity in skin cells. Mangifera indica L. is a popular economical and medicinal plant with numerous health-beneficial properties. The aqueous extracts of unripe fruit of Mangifera indica L. were obtained and subjected to HPLC and NMR analyses for the identification of bioactive compounds. The anti-glycation effect of Mango unripe fruit extracts was monitored by in vitro model system of AGEs (Advanced glycation end products) formation. Mango unripe fruit extracts significantly inhibited the AGEs formation in a dose-dependent manner. Meanwhile, Mango unripe fruit extracts possessed a comparable efficiency to commercialized Kojic acids in the inhibition of melanogenesis in B16-F10 melanoma cells. The UVA-induced cell damages can be prevented and repaired by Mango unripe fruit extracts in skin fibroblast CCD-966SK. Compared to the untreated control, Mango unripe fruit extracts significantly increased the cell viability while being applied before (36%) or after (43%) UVA irradiation. These results verified the potential application of Mango unripe fruit extracts in the skin protection and recovery from UVA irradiation, as well as the suppression of AGEs formation and melanogenesis.

KEY TECHNIQUES OF MULTI-BODY MODELING OF OCCUPANT RESTRAINT SYSTEM OF VEHICLE SIDE IMPACT

Based on multi-body dynamics, the simulation models of auto-side structures and occupant＇s dynamic responses are set up, using the occupant injury simulation software MADYMO3D. These models include auto-body structure, impact barrier, seat and dummy. Definitions of multi-body and joints and dynamics properties of joints based on FE combination models, of model setup are introduced. Kelvin element of MADYMO is introduced to show the force action between non-adjoining rigid bodies, too. Then all examples of the methods mentioned are given. By the comparison of simulation and real test, the contract curves between simulation and real test for main structures and biology mechanics properties of dummy are obtained. The result shows the accuracy and validity of the models.

Novel self-consistent mean field approximation and its application in strong interaction phase transitions

We propose a novel self-consistent mean field approximation method by means of a Fierz transformation,taking the Nambu-Jona-Lasinio model as an example.This new self-consistent mean field approximation introduces a new free parameter a to be determined experimentally.When a assumes the value of 0.5,the approximation reduces to the mean field calculation commonly used in the past.Subsequently,we study the influence of the undetermined parameter a on the phase diagram of the two-flavor strong interaction matter.The value of a plays a crucial role in the strong interaction phase diagram,as it not only changes the position of the phase transition point of strong interaction matter,but also affects the order of the phase transition.For example,when a is greater than the critical valueαc = 0.71,then the strong interaction matter phase diagram no longer has a critical end point.In addition,in the case of zero temperature and finite density,we found that when a>1.044,the pseudo-critical chemical potential corresponds to ～4-5 times the saturation density of the nuclear matter,which agrees with the expected results from the picture of the hadrons degree of freedom.The resulting equations of state of strong interaction matter at low temperatures and high densities will have an important impact on studies concerning the mass radius relationship of neutron stars and the merging process of binary neutron stars.

Self-consistent mean field approximation and application in three-flavor NJL model

In this study,we apply a self-consistent mean field approximation of the three-flavor Nambu–Jona-Lasinio(NJL)model and compare it with the two-flavor NJL model.The self-consistent mean field approximation introduces a new parameter,α,that cannot be fixed in advance by the mean field approach itself.Due to the lack of experimental data,the parameter,α,is undetermined.Hence,it is regarded as a free parameter and its influence on the chiral phase transition of strong interaction matter is studied based on this self-consistent mean field approximation.αaffects numerous properties of the chiral phase transitions,such as the position of the phase transition point and the order of phase transition.Additionally,increasingαwill decrease the number densities of different quarks and increase the chemical potential at which the number density of the strange quark is non-zero.Finally,we observed thatαaffects the equation of state(EOS)of the quark matter,and the sound velocity can be calculated to determine the stiffness of the EOS,which provides a good basis for studying the neutron star mass-radius relationship.

Transverse Ward-Takahashi identities and full vertex functions in different representations of QED3

We derive the transverse Ward-Takahashi identities(WTI)of N-dimensional quantum electrodynamics by means of the canonical quantization method and the path integration method,and subsequently attempt to prove that QED3 is solvable based on the transverse and longitudinal WTI,indicating that the full vector and tensor vertices functions can be expressed in terms of the fermion propagators in QED3.Further,we discuss the effect of differentγmatrix representations on the full vertex function.

Chiral symmetry restoration and properties of Goldstone bosons at finite temperature

We study chiral symmetry restoration by analyzing thermal properties of QCD's(pseudo-)Goldstone bo-sons,especially the pion.The meson properties are obtained from the spectral densities of mesonic imaginary-time correlation functions.To obtain the correlation functions,we solve the Dyson-Schwinger equations and the inhomo-geneous Bethe-Salpeter equations in the leading symmetry-preserving rainbow-ladder approximation.In chiral limit,the pion and its partner sigma degenerate at the critical temperature T_(c).At T≥T_(c),it was found that the pion rapidly dissociates,which signals deconfinement phase transition.Beyond the chiral limit,the pion dissociation temperature can be used to define the pseudo-critical temperature of the chiral phase crossover,which is consistent with that ob-tained by the maximum point of chiral susceptibility.A parallel analysis for kaon and pseudoscalar ss suggests that heavymesons maysurviveabove T_(c).

QCD phase diagram at finite isospin and baryon chemical potentials with the self-consistent mean field approximation

The self-consistent mean field approximation of the two-flavor NJL model,with a free parameter a to reflect the competition between the"direct"channel and the"exchange"channel,is employed to study the QCD phase structure at finite isospin chemical potentialμr,finite baryon chemical potentialμB and finite temperature T,and especially to study the location of the QCD critical point.Our results show that in order to match the corres-ponding lttice results of isospin density and energy density,the contributions of the"exchange"channel need to be considered in the framework of the NJL model,and a weighting factorα=0.5 should be taken.It is also found that for fixed isospin chemical potentials,the lower temperature of the phase transition is obtained with increasing a in the T-μplane,and the largest difference of the phase transition temperature with differentα's appears atμ1~1.5mm.Atμ=0 the temperature of the QCD critical end point(CEP)decreases with increasing r,while the critical baryon chemical potential increases.At high isospin chemical potential(μr=500 MeV),the temperature of the QCD tricritical point(TCP)increases with increasing a,and in the low temperature regions the system will.transition from the pion superfluidity phase to the normal phase asμB increases.At low density,the critical temperature of the QCD phase transition with differentα's rapidly increases withμ1 at the beginning,and then increases smoothly aroundμ1>300 MeV.In the high baryon density region,the increase of the isospin chemical potential will raise the critical baryon chemical potential of the phase transition.

On-shell mediator dark matter models and the Xenon1T excess

We present a dark matter model to explain the excess events in the electron recoil data recently reported by the Xenon1 T experiment. In our model, dark matter χ annihilates into a pair of on-shell particles Φ, which subsequently decay into the ψψ final state;ψ interacts with electrons to generate the observed excess events. Because of the mass hierarchy, the velocity of ψ can be rather large and can have an extended distribution, providing a good fit to the electron recoil energy spectrum. We estimate the flux of ψ from dark matter annihilations in the galaxy and further determine the interaction cross section, which is sizable but sufficiently small to allow ψ to penetrate the rocks to reach the underground labs.

Multi-agent mobile networking observation experiment at the air-sea interface of ocean eddy

Current climate forecasting has advanced to the stage of investigating mesoscale air-sea interactions. Recent studies have identified significant structural differences between the cores and edges of mesoscale eddies;however, the effects of these structural variations on air-sea fluxes and the Marine Atmospheric Boundary Layer(MABL) remain underexplored. Traditional observations often fail to capture the detailed structures of eddies, necessitating enhanced observations at high spatiotemporal resolution for mesoscale eddies. To address this, efforts have been made to develop multi-agent platforms and expendable air-sea interface observation technologies. A task-oriented observation scheme was developed to monitor the spatial characteristics of mesoscale eddies. The South China Sea(SCS) is rich in mesoscale eddies with rapid motion changes, requiring enhanced observations of the air-sea interface using multi-agent mobile networking. An anticyclonic eddy was observed in the eastern region of the Xisha Islands in the SCS, and we examined variations in air-sea fluxes across different regions within the eddy.