An improved model for the acoustic radiation impedance of the mouth based on an equivalent electrical network

This paper proposes a model for acoustic radiation impedance of the mouth in the form of the equivalent electrical network. Five known models of radiation impedance are compared: radiation of a circular piston set in a spherical baffle: radiation of a circular piston set in an infinite baffle, the Flanagan model, the Wakita and Fant model, and the Stevens, Kasowski and Fant model. The proposed model most accurately approximates the radiation impedance of a circular piston set in a spherical baffle. Differences between the acoustic resistance and reactance calculated by the proposed model and the piston set in a spherical baffle of 9 cm radius are relatively small in the kr < 2 region. The deviations in calculated values of the acoustic resistance and the reactance are within ±0.023 × ρc/A_m and ±0.008 × ρc/A_m, respectively, where A_m denotes the area of the mouth aperture. The accuracy of the proposed model is demonstrated by vowel formant frequency calculations. Differences in formant frequencies calculated by applying the proposed model and the piston set in a spherical baffle model are less than 0.3%.     

The structure of the odd-A nuclei withA≈130 and the problem ofγ-softness

The negative parity states in the^{123, 125, 131}Cs and the¹³¹La nuclei are described in the framework of the particle-core coupling model. In order to study the problem of gamma softness, the following two core models are used:(1) the rigid triaxial rotor model, and(2) theγ-unstable model withγ-dependent inertial functions. The properties of the odd-A nuclei with rigid and soft cores are compared with the experimental data. The results do not allow to draw a definite conclusion about the softness. When seeking properties which could help to distinguish between soft and rigid nuclei it has been found that some spectroscopic factors for the proton stripping reaction are sensitive to the gamma softness.     

On the volume dependence of the total energy and the equation of state for copper

The total energy of metallic copper as a function of the atomic radius is calculated. The model assumes that in copper one has nearly free s-electrons in OPW states and d-electrons localized at the ions in atomic-like orbitals. The coulomb interactions in the energy are calculated by using the model of neutral spheres, while the kinetic and exchange contributions to the S²-energy are approximated by the exchange charge model. Instead of the familiar Born-Mayer repulsion, which was found to lead to controversies in the case of copper, the d-type interaction energy shows a more complex behaviour having a minimum near the equilibrium atomic radius. The prediction for the cohesive energy and the equation of state is reasonable, the calculated value for the Ashcroft radius for s-electrons agrees remarkably with the ab initio estimate. The atomic-like orbitals minimizing the total energy are somewhat more extended than the real atomic wave-functions.     

Spontaneous CP violation in the left-right model and the kaon system

A left-right model with spontaneous CP breakdown, consistent with the particle physics phenomenology, is presented. Constraints on free parameters of the model: mass of the new righthanded gauge boson M₂ and ratio r of the two vacuum expectation valuesof the bidoublet, are found from the measurement of ϵ in the kaon system. For most of the parameter space, M₂ is restricted to be below 10 TeV Higher masses can be achieved only by fine tuning of Kobayashi-Maskawa matrix elements, quark masses, r and the phase α which is the unique source of CP violation in the model. Large number of combinations of signs of quark masses, which are observables of the model, are found to be not allowed since they contradict with data. The range of ϵ'/ϵ the model predicts is around 10⁻⁴ in magnitude.     

One-pion exchange currents effect on the allowed beta-decays in the 1p shell nuclei

A calculation is performed of theft- values for beta-decay allowed transitions in theA=6 ?14 nuclei. The 1p-shell model and the one-pion exchange model are used. It is found that the mesonic corrections are state dependent and may take large values when logft>4.0.     

Hadroproduction of hyperons in the framework of the quark-parton model

TheSU (6)×O(3) classification of baryons is applied to the hyperon production in the framework of the quark-diquark fusion model. The model predictions are compared with the data measured inpp interactions at various energies. The contribution of the decay of the high-lying hyperon resonances to the observed spectra is estimated and found essential.     

On the recombination mechanism of quarks into a baryon in proton fragmentation

The similarity and difference between our quark cascade model with recombination mechanism and Van Hove's quark fragmentation-recombination model are discussed. Van Hove's fragmentation-recombination model is extended to the model which describesx-dependence of the hadron spectra as well as the baryon multiplicities by using our diffusion equation. The recombination probability in Van Hove's model can be related with the recombination factor λ′ in our diffusion equation. Thex-dependence of the hadron spectra causes another restriction on the recombination probability in Van Hove's model. The inclusive spectra of mesons, proton andΔ ⁺⁺ in proton fragmentation and baryon multiplicities except∑ ^? multiplicity are explained by both our model with recombination mechanism and the model with recombination mechanism a la Van Hove. But the ration(∑ ^?)/n(∑ ^+;) may not be explained by naive quark-parton model with recombination mechanism without considering quark spin.     

On the reaction pp → ppη near the threshold

The reaction pp → ppη near the kinematical threshold is considered in the framework of the model, which includes the pp final states interaction (FSI). The Coulomb and strong effects of the pp FSI are calculated correctly in the model “Coulomb + Yamaguchi potential”. The pp FSI is shown to provide the main contribution to the energy dependence of the total cross section of the pp → ppη reaction close to threshold. The energy behavior of the total cross section is predicted in agreement with the data in the excess energy region < 15MeV. The predictions for different spectra are also performed.     

RPA description of the electric polarizability of the nucleon

Excited states of the nucleon are described as RPA configurations on a mean-field ground state taken from the MIT bag model. A residual interaction of a structure as in the Nambu-Jona-Lasinio model is used. The particlehole states are coupled to good total angular momentum and isospin. Valence excitations of particle-hole type and quark-antiquark (q $\bar q$ ) states from the Dirac-sea are included. The dependence of the baryon spectrum and multipole response functions on the coupling constantG is studied. At critical values ofG the 3q-ground state becomes degenerate with strongly collectiveq99-2 modes. The model is used to calculate the averaged electric polarizability of the neutron and the protonα. Without residual interactionα=7·10^?4 fm ³ is found. With residual interaction the value increases toα=(?11)·10^?4 fm ³. The measured value ofα is reproduced within experimental error bars.     

A continuum calculation for the giant dipole resonance in28Si including the effect of collective correlations

Continuum shell model calculations for the giant dipole resonance in²⁸Si based on both the 1p 1h model and the collective correlation model are described and the results compared with experiment. The eigenchannel theory of nuclear reactions has been used to include the effect of the particle continuum.     

Generalized Landau-Lifshitz models on the interval

We study the classical generalized gln Landau-Lifshitz (L-L) model with special boundary conditions that preserve integrability. We explicitly derive the first non-trivial local integral of motion, which corresponds to the boundary Hamiltonian for the sl₂ L-L model. Novel expressions of the modified Lax pairs associated to the integrals of motion are also extracted. The relevant equations of motion with the corresponding boundary conditions are determined. Dynamical integrable boundary conditions are also examined within this spirit. Then the generalized isotropic and anisotropic gln Landau-Lifshitz models are considered, and novel expressions of the boundary Hamiltonians and the relevant equations of motion and boundary conditions are derived.     

Variational calculations on the energy levels of graphene quantum antidots

The critical properties of the two-dimensional Ising and Blume-Capel model on directedsmall-world lattices with quenched connectivity disorder are investigated. The disordered system is simulated by applying the Monte Carlo method with heat bath update algorithm and histogram re-weighting techniques. The critical temperature, as well as the critical exponents are obtained. For both models the critical parameters have been obtained for several values of the rewiring probability p. It is found that these disorder systems do not belong to the same universality class as two-dimensional ferromagnetic model on regular lattices. In particular, the Blume-Capel model, with zero crystal field interaction, on a directedsmall-world lattice presents a second-order phase transition for p < p _c , and a first-order phase transition for p > p _c , where p _c  ≈ 0.25. The critical exponents for p < p _c are different from those of the same model on a regular lattice, but are identical to the exponents of the Ising model on directedsmall-world lattice.     

Random Ising model in the magnetic field at T = 0: I. The distribution of the effective fields

The integral equation for the distribution function of the effective fields in the random Ising model in the finite external field is solved exactly at zero temperature in the one-dimensional case for 1) dilute ferromagnet, 2) dilute antiferromagnet and 3) ±J model. The ground state characteristics of these systems are obtained. In particular the effective fields in the ±J model are shown to have a triangular distribution in the zero external field limit.     

On the role of image forces in chemisorption theory

The Extended Anderson Hamiltonian is used to study the effect of fluctuations of an adatom charge Q on the ionic part of the chemisorption energy. It is shown that dynamical effects essentially modify the classical expression E = ? ?Q² for the energy of interaction between a static charge Q and a metal (? is the interaction energy for a unit charge). The exact solution for the one-electron two-level model as well as a variational solution for the Extended Anderson Hamiltonian model are given. Validity conditions for a variety of approximate schemes are studied. The results are presented for the Extended Anderson Hamiltonian model parameterized so as to describe some aspects of the Li/W and Li/Mo chemisorption systems.     

Composite nucleon approach to the deuteron problem

A composite model is suggested for the nucleons by assuming a longrange strong gluon force between a diquark boson B and a quark A. In the proton, A is trapped inside B in an oscillator potential and, in the neutron, A is on the surface of B in a hydrogenlike state. Nucleon form factors are obtained in agreement with experiments. The model contains a mechanism for a large effective mass of the quark A. When B is identified with π and A with μ, one can fix the gluon charge value and obtain the magnetic moments of the proton and neutron. The (πμ) atomic model for the nucleon can be used to construct the deuteron on a hydrogen molecule model. It leads to values for the binding energy, electric quadrupole moment, and form factors of the deuteron that are in agreement with experiments.     

Reflection asymmetry in the calculations of nuclear mass parameters in terms of the modified oscillator model

The cranking model has been adapted to the four dimentional (?₂, ?₃, ?₄, ?₅) nuclear shape parametrization of the Nilsson model. Some advantages of the nuclear shape parametrization in terms of Legendre polynomials are pointed out. The most characteristic properties of the mass parameters and their dependence upon the shell structure are illustrated and discussed for some actinide nuclei.     

Prediction of heat storage coefficient of some loose granular materials on the basis of structure and packing of the grains

A theoretical expression is presented to predict the heat storage coefficient (HSC) of two-phase granular systems from the values of HSC of the constituent phases and their volume fractions. Particles are assumed to be a simple cube, arranged in a regular manner in a cubic geometry. Theoretical calculations of the HSC of loose granular materials using the proposed model have been carried out. The HSCs of the materials have been determined experimentally by using a plane heat source. The values obtained are predicted by the proposed model. The model is also tested on other reported values of the HSC. A close agreement has been found between predicted and experimental values.     

Theory of the radial distribution functions in α-AgI

The three partial radial distribution functions g_Ag-Ag(r), g_Ag-I(r) and g_I-I(r) in α-AgI are calculated on the basis of the fact that I-ions form a bcc lattice and Ag-ions are randomly distributed over the 12(d) sites. The short-range order between the Ag-ions is described in terms of the microcrystalline model which has been recently divised by the present author on the occasion of the study on the superionic transition in CuI. The calculated results are in good agreement with those of the computer simulation of Vashishta and Rahman. We have an evidence that the Ag-ions are correlated in order to decrease the Coulomb interaction between them (not core-core repulsion) and the microcrystalline model is suitable to represent the correlated region. We discuss the relation between the microcrystalline model and the caterpillar mechanism.     

Dynamic phase transitions in the kinetic spin-1 Blume-Capel model on the Bethe lattice

The stationary states of the kinetic spin-1 Blume-Capel (BC) model on the Bethe lattice are analyzed in detail in terms of recursion relations. The model is described using a Glauber-type stochastic dynamics in the presence of a time-dependent oscillating external magnetic field (h) and crystal field (D) interactions. The dynamic order parameter, the hysteresis loop area and the dynamic correlation are calculated. It is found that the magnetization oscillates around nonzero values at low temperatures (T) for the ferromagnetic (F) phase while it only oscillates around zero values at high temperatures for the paramagnetic (P) phase. There are regions of the phase space where the two solutions coexist. The dynamic phase diagrams are obtained on the (kT/J,h/J) and (kT/J,D/J) planes for the coordination number q=4. In addition to second-order and first-order phase transitions, dynamical tricritical points and triple points are also observed.