Analysis on Heavy Quarkonia Transitions with Pion Emission in Terms of the QCD Multipole Expansion and Determination of Mass Spectra of Hybrids

One of the most important tasks in high energy physics is search for the exotic states, such as glueball, hybrid and multi-quark states. The transitions $\psi(ns)\to \psi(ms)+\pi\pi$ and $\Upsilon(ns)\to \Upsilon(ms)+\pi\pi$ attract great attentions because they may reveal characteristics of hybrids. In this work, we analyze those transition modes in terms of the theoretical framework established by Yan and Kuang. It is interesting to notice that the intermediate states between the two gluon-emissions are hybrids, therefore by fitting the data, we are able to determine the mass spectra of hybrids. The ground hybrid states are predicted as 4.23 GeV (for charmonium) and 10.79 GeV (for bottonium) which do not correspond to any states measured in recent experiments, thus it may imply that very possibly, hybrids mix with regular quarkonia to constitute physical states. Comprehensive comparisons of the potentials for hybrids whose parameters are obtained in this scenario with the lattice results are presented.Comment: 16 pages, 2 figur

Stability of Multi-Dimensional Switched Systems with an Application to Open Multi-Agent Systems

Extended from the classic switched system, themulti-dimensional switched system (MDSS) allows for subsystems(switching modes) with different state dimensions. In this work,we study the stability problem of the MDSS, whose state transi-tion at each switching instant is characterized by the dimensionvariation and the state jump, without extra constraint imposed.Based on the proposed transition-dependent average dwell time(TDADT) and the piecewise TDADT methods, along with the pro-posed parametric multiple Lyapunov functions (MLFs), sufficientconditions for the practical and the asymptotical stabilities of theMDSS are respectively derived for the MDSS in the presenceof unstable subsystems. The stability results for the MDSS areapplied to the consensus problem of the open multi-agent system(MAS) which exhibits dynamic circulation behaviors. It is shownthat the (practical) consensus of the open MAS with disconnectedswitching topologies can be ensured by (practically) stabilizingthe corresponding MDSS with unstable switching modes via theproposed TDADT and parametric MLF methods.Comment: 12 pages, 9 figure

Aeroacoustic noise reduction design of a landing gear structure based on wind tunnel experiment and simulation

In the process of aircraft landing, the aerodynamic noise of the landing gear constitutes an appreciable part of the airframe noise. Therefore it is important to dedicate research efforts to study of aerodynamic noise of landing gear and its structural parts. Acoustic wind tunnel test on landing gear is designed to measure aerodynamic noise of structural parts of landing gear such as pillar and torque arm. Aerodynamic noise spectrum characteristic and radiation directive characteristic of structural parts in different velocities are established. The effect of flow velocity to noise is analyzed. Two noise reduction designs are proposed in the paper. The effect of the relative position of pillar and torque arm to structural noise is considered based on simulations and testing. Simulation method to assess the noise reduction effect of torque arm shape modification is adopted. The results demonstrate that structural noise can be appreciably reduced by placing torque arm behind the pillar as well as by modifying the shape of the torque arm. In total, the study holds reference value to the ongoing research activities on aerodynamic noise of landing gear and design method for low noise operation of the gear

Static test rig development and application for an airliner’s hyperstatic aero-engine pylon structure

A set of test system, which is suitable for static test of a hyperstatic aero-engine pylon structure of a certain aircraft, was designed according to the requirements of static structure test. This test technology solved some key problems such as support stiffness simulation of hyperstatic engine pylon and aero-engine loading simulation. Based on these experimental techniques, the static test on a hyperstatic aero-engine pylon of a certain aircraft has been completed in the paper. The test results testified to the stable and reliable working performance of the test system. And the aero-engine pylon, the test specimen, didn’t produce any crack or harmful large deformation under all work conditions, indicating that it has met the design requirements on both static strength and stiffness. The test technology can be applied in static tests of similar hyperstatic test specimen. The test data can serve as a basis for structural static strength and stiffness property evaluation of the aero-engine pylon

Self-adaptive parameter and strategy based particle swarm optimization for large-scale feature selection problems with multiple classifiers

This work was partially supported by the National Natural Science Foundation of China (61403206, 61876089,61876185), the Natural Science Foundation of Jiangsu Province (BK20141005), the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (14KJB520025), the Engineering Research Center of Digital Forensics, Ministry of Education, and the Priority Academic Program Development of Jiangsu Higher Education Institutions.Peer reviewedPostprin

Neutrino decay as a possible interpretation to the MiniBooNE observation with unparticle scenario

In a new measurement on neutrino oscillation $\nu_{\mu}\to\nu_e$, the MiniBooNE Collaboration observes an excess of electron-like events at low energy and the phenomenon may demand an explanation which obviously is beyond the oscillation picuture. We propose that heavier neutrino $\nu_2$ decaying into a lighter one $\nu_1$ via the transition process $\nu_{\mu}\to \nu_e+X$ where $X$ denotes any light products, could be a natural mechanism. The theoretical model we employ here is the unparticle scenario established by Georgi. We have studied two particular modes \nu_\mu\to \nu_e+\Un and $\nu_\mu\to \nu_e+\bar\nu_e+\nu_e$. Unfortunately, the number coming out from the computation is too small to explain the observation. Moreover, our results are consistent with the cosmology constraint on the neutrino lifetime and the theoretical estimation made by other groups, therefore we can conclude that even though neutrino decay seems plausible in this case, it indeed cannot be the source of the peak at lower energy observed by the MiniBooNE collaboration and there should be other mechanisms responsible for the phenomenon.Comment: 14 pages, conclusions are changed; published version for EPJ