[en] Controlling chaos and chaotification using delayed continuous feedback is studied in this paper. The effects of time delay parameters on the dynamics of the Chen-Lee system were numerically studied. The system displays comprehensive dynamic behaviors, such as fixed points, periodic motion, and chaotic motion. The maximum Lyapunov exponent, time histories, and phase trajectories all indicated that chaotic motion could successfully be controlled. Period doubling routes to chaos and inverse period doubling phenomena were also found in the Chen-Lee system. This paper points out that the time delay parameters are good switch keys. The dynamics of this system can be controlled under appropriate feedback gains and delay times. This study showed that the delayed control feedback (DCF) method is very straightforward, and that it is easy to switch from a chaotic trajectory to a regular periodic orbit while simultaneously improving the system's properties

[en] We report on STAR measurements of global polarization for vector mesons K*⁰(892) and φ(1020) at midrapidity from noncentral Au+Au collisions at √s_NN= 200 GeV. The measured diagonal spin density matrix elements for particles up to a transverse momentum 5 GeV/c are ρ₀₀ = 0.36 ± 0.02 (stat) ± 0.13 (sys) for K*⁰(892) and ρ₀₀ = 0.38 ± 0.01 (stat) ± 0.04 (sys) for φ(1020) with respect to the reaction plane, where 1/3 is the value for no polarization. With respect to the vector mesons' production planes, ρ₀₀ for K*⁰(892) and φ(1020) in Au+Au and for φ(1020) mesons in p+p collisions at √s_NN= 200 GeV is also presented. There is no significant difference for the measured spin alignment between Au+Au and p+p collisions with our data sample. We have also obtained an upper limit |P_Λ,Λ_-bar < 0.02 for Λ(Λ-bar) global polarization

[en] The Lee model was introduced in the 1950s as an elementary quantum field theory in which mass, wave function, and charge renormalization could be carried out exactly. In early studies of this model it was found that there is a critical value of g², the square of the renormalized coupling constant, above which g₀², the square of the unrenormalized coupling constant, is negative. Thus, for g² larger than this critical value, the Hamiltonian of the Lee model becomes non-Hermitian. It was also discovered that in this non-Hermitian regime a new state appears whose norm is negative. This state is called a ghost state. It has always been assumed that in this ghost regime the Lee model is an unacceptable quantum theory because unitarity appears to be violated. However, in this regime while the Hamiltonian is not Hermitian, it does possess PT symmetry. It has recently been discovered that a non-Hermitian Hamiltonian having PT symmetry may define a quantum theory that is unitary. The proof of unitarity requires the construction of a new time-independent operator called C. In terms of C one can define a new inner product with respect to which the norms of the states in the Hilbert space are positive. Furthermore, it has been shown that time evolution in such a theory is unitary. In this paper the C operator for the Lee model in the ghost regime is constructed in the V/Nθ sector. It is then shown that the ghost state has a positive norm and that the Lee model is an acceptable unitary quantum field theory for all values of g²

[en] The dimensional analysis technique is used to formulate a correlation between ozone generation rate and various parameters that are important in the design and operation of positive wire-to-plate corona discharges in indoor air. The dimensionless relation is determined by linear regression analysis based on the results from 36 laboratory-scale experiments. The derived equation is validated by experimental data and a numerical model published in the literature. Applications of such derived equation are illustrated through an example selection of the appropriate set of operating conditions in the design/operation of a photocopier to follow the federal regulations of ozone emission. Finally, a new current-voltage characteristic equation is proposed for positive wire-to-plate corona discharges based on the derived dimensionless equation.

[en] A non-Hermitian Hamiltonian has a real positive spectrum and exhibits unitary time evolution if the Hamiltonian possesses an unbroken PT (space-time reflection) symmetry. The proof of unitarity requires the construction of a linear operator called C. It is shown here that C is the complex extension of the intrinsic parity operator and that the C operator transforms under the Lorentz group as a scalar

[en] New results on φ-meson elliptic flow ν2 and nuclear modification factor RCP measurement from RHIC 2004 run (Run-IV) have been reviewed. Knowledge about these results are discussed

[en] In seesaw models with more than one generation of light and heavy neutrinos, ν and N, respectively, it is possible to have sizable mixing between them for heavy-neutrino masses of order 100 GeV or less. We explore this possibility further, taking into account current experimental constraints, and study its effect on Higgs-boson decays in the contexts of seesaw models of types I and III. We find that in the type-I case the Higgs decay into a pair of light and heavy neutrinos, h→νN, could increase the total Higgs width in the standard model by up to almost 30% for a relatively light Higgs-boson, which would significantly affect Higgs searches at the LHC. The subsequent prompt decay of N into three light fermions makes this Higgs decay effectively a four-body decay. We further find that, in the presence of the large light-heavy mixing, these four-body Higgs decays can have rates a few times larger than their standard-model counterparts and therefore could provide a potentially important window to reveal the underlying seesaw mechanism.

[en] Advances in high-performance computational capabilities enable scientific simulations with increasingly realistic physical representations. This situation is especially true of turbulent combustion involving multiscale interactions between turbulent flow, complex chemical reaction, and scalar transport. A fundamental understanding of combustion processes is crucial to the development and optimization of next-generation combustion technologies operating with alternative fuels, at higher pressures, and under less stable operating conditions, such as highly dilute, stratified mixtures. Direct numerical simulations (DNS) of turbulent combustion resolving all flow and chemical features in canonical configurations are used to improve fundamental understanding of complex flow processes and to provide a database for the development and validation of combustion models. A description of the DNS solver and its optimization for use in massively parallel simulations is presented. Recent DNS results from a series of three combustion configurations are presented: soot formation and transport in a nonpremixed ethylene jet flame, the effect of fuel stratification in methane Bunsen flames, and extinction and reignition processes in nonpremixed ethylene jet flames

[en] The notch sensitivity of tensile specimens of TiAl and K418 alloys has been investigated, and the notch strength has been quantitatively analyzed. The fracture surface of the specimens has also been observed and analyzed by scanning electron microscopy (JEOL-6700F). By comparing notch rod tensile specimens and special notch rod tensile specimens, it was found that the basic nature, fracture driving force, and fracture criteria of the brittle TiAl alloy and the ductile K418 alloy are different. The final fracture of the K418 alloy is controlled by strain and not by stress, and the specimens do not exhibit notch sensitivity. However, the final fracture of the TiAl alloy is controlled by stress, and the specimens exhibit small notch sensitivity. For the special notch rod tensile specimens, the K418 specimens do not exhibit notch sensitivity. However, for the TiAl alloy, when the notch depth reaches 10% of the specimen diameter, the tensile strength decreases, and when the notch depth reaches 20% of the specimen diameters, the tensile strength sharply decreases.

[en] The crystallization kinetics of a-Ge thin film induced by a thin Ni layer under thermal annealing and pulsed laser irradiation has been studied. Under thermal annealing, the crystallization temperature and activation energy for crystallization of a-Ge in the a-Ge/Ni bilayer recording film were significantly reduced to 385 deg. C and 2.4 eV, respectively, due to the fast Ge diffusion in the already formed germanide phases. The reaction exponent m of ∼1.7 for the a-Ge/Ni bilayer corresponds to a crystallization process in which grain growth occurs with nucleation and the nucleation rate decreases with the progress of the grain growth process. Under pulsed laser irradiation, the maximum data-transfer rates of 22, 56, 74, and 112 Mbits/s can be achieved in the write-once blue-ray disk at the recording powers of 3, 4, 5, and 6 mW, respectively.