The use of the chatter mode in self-adaptive systems

Chatter mode is used advantageously if the ideal model dynamics is described by a switching function, the chatter mode is reached quickly and then sustained, the chatter frequency is reduced, and any zero in the plant transfer function is cancelled

Studying Diquark Structure of Heavy Baryons in Relativistic Heavy Ion Collisions

We propose the enhancement of $\Lambda_c$ yield in heavy ion collisions at RHIC and LHC as a novel signal for the existence of diquarks in the strongly coupled quark-gluon plasma produced in these collisions as well as in the $\Lambda_c$. Assuming that stable bound diquarks can exist in the quark-gluon plasma, we argue that the yield of $\Lambda_c$ would be increased by two-body collisions between $ud$ diquarks and $c$ quarks, in addition to normal three-body collisions among $u$, $d$ and $c$ quarks. A quantitative study of this effect based on the coalescence model shows that including the contribution of diquarks to $\Lambda_c$ production indeed leads to a substantial enhancement of the $\Lambda_c/D$ ratio in heavy ion collisions.Comment: Prepared for Chiral Symmetry in Hadron and Nuclear Physics (Chiral07), Nov. 13-16, 2007, Osaka, Japa

Exotic mesons with hidden charm and bottom near thresholds

We study heavy hadron spectroscopy near heavy meson thresholds. We employ heavy pseudoscalar meson P and heavy vector meson P* as effective degrees of freedom and consider meson exchange potentials between them. All possible composite states which can be constructed from the P and P* mesons are studied up to the total angular momentum J <= 2. We consider, as exotic states, isosinglet states with exotic J^{PC} quantum numbers and isotriplet states. We solve numerically the Schr\"odinger equation with channel-couplings for each state. We found B(*)barB(*) molecule states for I^G(J^{PC}) = 1^+(1^{+-}) correspond to the masses of twin resonances Zb(10610) and Zb(10650). We predict several possible B(*)barB(*) bound and/or resonant states in other channels. On the other hand, there are no B(*)barB(*) bound and/or resonant states whose quantum numbers are exotic.Comment: 10 pages, 1 figure, to appear in the proceedings of The 5th International Workshop on Charm Physics (Charm 2012

Effects of quark matter and color superconductivity in compact stars

The equation of state for quark matter is derived for a nonlocal, chiral quark model within the mean field approximation. We investigate the effects of a variation of the form factors of the interaction on the phase diagram of quark matter under the condition of beta-equilibrium and charge neutrality. Special emphasis is on the occurrence of a diquark condensate which signals a phase transition to color superconductivity and its effects on the equation of state. We calculate the quark star configurations by solving the Tolman- Oppenheimer- Volkoff equations and obtain for the transition from a hot, normal quark matter core of a protoneutron star to a cool diquark condensed one a release of binding energy of the order of Delta M c^2 ~ 10^{53} erg. We study the consequences of antineutrino trapping in hot quark matter for quark star configurations with possible diquark condensation and discuss the claim that this energy could serve as an engine for explosive phenomena. A "phase diagram" for rotating compact stars (angular velocity-baryon mass plane) is suggested as a heuristic tool for obtaining constraints on the equation of state of QCD at high densities. It has a critical line dividing hadronic from quark core stars which is correlated with a local maximum of the moment of inertia and can thus be subject to experimental verification by observation of the rotational behavior of accreting compact stars.Comment: 14 pages, 12 figures, Talk given at 2nd International Workshop on Hadron Physics: Effective Theories of Low-Energy QCD, Coimbra, Portugal, 25-29 Sep 200

FE analysis on tube hydroforming of small diametr ZM21 magnesium alloy tube

Tube hydroforming (THF) is one of the plasticity processing methods. Tubular parts, for instance automotive components are expanded by forces such as internal pressure and axial compression in order to deform an objective shape. THF has less restriction on shape and size of workpieces owing to adopting the liquid tool. The demand of a small diameter magnesium alloy tubular parts have been increased for applying small medical and electronic devices. In this study, it was investigated that influence of process conditions such as processing temperature, internal pressure and axial feeding amount on formability of small diameter ZM21 magnesium alloy tube with outer diameter of 2.0mm and thickness of 0.20mm. Furthermore, the processing conditions for improving the formability of material in THF were examined. For prior evaluation of deformation characteristics in the warm THF of small diameter ZM21 magnesium alloy tube, a finite element (FE) simulation was conducted. The FE method (FEM) code was used LS-DYNA 3D for analysis of the FE model of the tube and the dies. The material characteristics were obtained by tensile test and fracture test. From FE analysis results, it was elucidated that effect of the processing temperature, the variable internal pressure and the axial feeding amount on deformation behavior. The formability of ZM21 magnesium alloy tube was improved by processing at 250 C. The difference of deformation characteristic between FE results and experimental results was compared. As the results, the processing condition which could improve the formability of ZM21 tube was clarified using this FE model. The effect of adding the straightening stage in the loading path after the preform on formability was investigated. The thinning of the wall thickness of the tube was inhibited by calibration after the axial feeding

Chiral symmetry breaking and stability of quark droplets

We discuss the stability of strangelets -- quark droplets with strangeness -- in the Nambu--Jona-Lasinio model supplemented by a boundary condition for quark confinement. Effects of dynamical chiral symmetry breaking are considered properly inside quark droplets of arbitrary baryon number. We obtain the energy per baryon number of quark droplets with baryon number from one to thousands. It is shown that strangelets are not the ground states as compared with nuclei, though they can be locally stable