The simulation of magnetorheological elastomers adaptive tuned dynamic vibration absorber for automobile engine vibration control

The aim of this article is to investigate the use of a Dynamic Vibration Absorber to control vibration of engine by using simulation. Traditional means of vibration control have involved the use of passive and more recently, active methods. This study is different in that it involves an adaptive component in the design of vibration absorber using magnetorheological elastomers (MREs) as the adaptive spring. MREs are kind of novel smart material whose shear modulus can be controlled by applied magnetic field. In this paper, the vibration mode of a simple model of automobile engine is simulated by Finite Element Method (FEM) analysis. Based on the analysis, the MREs Adaptive Tuned Dynamic Vibration Absorber (ATDVA) is presented to reduce the vibration of the engine. Simulation result indicate that the control frequency of ATDVA can be changed by modifing the shear modulus of MREs and the vibraion reduction efficiency of ATDVA are also evaluated by FEM analysis

Kinetic energy and spin-orbit splitting in nuclei near neutron drip line

Two important ingredients of nuclear shell-structure, kinetic energy and spin-orbit splitting, are studied as a function of orbital angular momenta \ell and binding energies, when binding energies of neutrons decrease towards zero. If we use the standard parameters of the Woods-Saxon potential in \beta stable nuclei and approach the limit of zero binding energy from 10 MeV, the spin-orbit splitting for n=1 orbitals decreases considerably for \ell=1, while for \ell > 2 little decreasing is observed in the limit. In contrast, the kinetic energy decreases considerably for \ell \simleq 3. The smaller the \ell values of orbitals, the larger the decreasing rate of both kinetic energy and spin-orbit splitting. The dependence of the above bservation on the diffuseness of potentials is studied.Comment: 12 pages, 3 figures, submitted to Nucl. Phy

Design of Robust Fuzzy Sliding-Mode Controller for a Class of Uncertain Takagi-Sugeno Nonlinear Systems

This paper presents the fuzzy design of sliding mode control (SMC) for nonlinear systems with uncertainties, which can be represented by a Takagi-Sugeno (T-S) model. There exist the parameter uncertainties in both state and input matrices, as well as the matched external disturbance. The key feature of this work is the great ability of the controller to deal with systems without assuming that the control matrices of each local T-S model to be same and knowing the priori information of the upper norm-bounds of uncertainties. A sufficient condition for the existence of the desired fuzzy SMC is obtained by solving a set of linear matrix inequalities (LMIs). The reachability of the specified sliding surface is proven. A numerical example is illustrated in order to show the validity of the proposed scheme

Effect of Tensor Correlations on Gamow-Teller States in 90Zr and 208Pb

The tensor terms of the Skyrme effective interaction are included in the self-consistent Hartree-Fock plus Random Phase Approximation (HF+RPA) model. The Gamow-Teller (GT) strength function of 90Zr and 208Pb are calculated with and without the tensor terms. The main peaks are moved downwards by about 2 MeV when including the tensor contribution. About 10% of the non-energy weighted sum rule is shifted to the excitation energy region above 30 MeV by the RPA tensor correlations. The contribution of the tensor terms to the energy weighted sum rule is given analytically, and compared to the outcome of RPA.Comment: 13 pages, 2 figures,2 table

Spin-isospin excitations as quantitative constraints for the tensor force

Gamow-Teller (GT) and charge-exchange spin-dipole (SD) excitation energies in 90Zr and 208Pb are systematically studied to determine the appropriate magnitude of the tensor terms of the Skyrme interactions. We have found that the centroid energies of GT and SD excitations are sensitive to the adopted strengths of the triplet-even and triplet-odd tensor interactions. Especially, the 1- SD state plays a crucial role in constraining the triplet-even part while the triplet-odd part is related rather to the GT peaks. Among the 36 TIJ parameter sets that include nonperturbatively the tensor terms, the four sets, T21, T32, T43, and T54, give reasonable results for the centroid energies in comparison with the experimental data. The sign and magnitude of the tensor terms are also discussed when these terms are added to the existing Skyrme interactions SGII and SLy5. The triplet-even strength can be constrained in a narrow range by using the available experimental data while further empirical data are needed to set a constraint on the triplet-odd term

Three-Particle Correlations from Parton Cascades in Au+Au Collisions

We present a study of three-particle correlations among a trigger particle and two associated particles in Au + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV using a multi-phase transport model (AMPT) with both partonic and hadronic interactions. We found that three-particle correlation densities in different angular directions with respect to the triggered particle (`center', `cone', `deflected', `near' and `near-away') increase with the number of participants. The ratio of `deflected' to `cone' density approaches to 1.0 with the increasing of number of participants, which indicates that partonic Mach-like shock waves can be produced by strong parton cascades in central Au+Au collisions.Comment: 9 pages, 6 figures; Final version to appear in Physics Letters

New mechanism to cross the phantom divide

Recently, type Ia supernovae data appear to support a dark energy whose equation of state $w$ crosses -1, which is a much more amazing problem than the acceleration of the universe. We show that it is possible for the equation of state to cross the phantom divide by a scalar field in the gravity with an additional inverse power-law term of Ricci scalar in the Lagrangian. The necessary and sufficient condition for a universe in which the dark energy can cross the phantom divide is obtained. Some analytical solutions with $w<-1$ or $w>-1$ are obtained. A minimal coupled scalar with different potentials, including quadratic, cubic, quantic, exponential and logarithmic potentials are investigated via numerical methods, respectively. All these potentials lead to the crossing behavior. We show that it is a robust result which is hardly dependent on the concrete form of the potential of the scalar.Comment: 11 pages, 5 figs, v3: several references added, to match the published versio