Diassociativity in Conjugacy Closed Loops

Let Q be a conjugacy closed loop, and N(Q) its nucleus. Then Z(N(Q)) contains all associators of elements of Q. If in addition Q is diassociative (i.e., an extra loop), then all these associators have order 2. If Q is power-associative and |Q| is finite and relatively prime to 6, then Q is a group. If Q is a finite non-associative extra loop, then 16 ∣ |Q|.

Efficient Simulation of Freak Waves in Random Oceanic Sea States

Numerical simulations of freak wave generation are studied in random oceanic sea states described by JONSWAP spectrum. The evolution of initial random wave trains is numerically carried out within the framework of the modified four-order nonlinear Schroedinger equation (mNLSE), and some involved influence factors are also discussed. Results show that if the sideband instability is satisfied, a random wave train may evolve into a freak wave train, and simultaneously the setting of the Phillips parameter and enhancement coefficient of JONSWAP spectrum and initial random phases is very important for the formation of freak waves. The way to increase the generation efficiency of freak waves though changing the involved parameters is also presented.

Mossbauer spectroscopy and chemical bonds in BaFe12O19 hexaferrite

Barium hexaferrite was synthesized by chemical co-precipitation. Its Mossbauer spectra were obtained. A semi-empirical model, based on the Phillips theory of bonding, has been developed for quantitative explanation of the Mossbauer isomer shifts of Fe ions in BaFe12O19 crystals. The results show that, using the relationship between isomer shifts and covalency, the site assignments in hexaferrites will be resolved easily. This paper provides a powerful tool for studying other members of the hexagonal ferrimagnetic oxides family.

The influence of bond valence on bond covalency in RMn2O5 (R=La, Pr, Nd, Sm, Eu)

The relationship between bond valence and bond covalency in RMn2O5 (R = La, Pr, Nd, Sm, Eu) has been investigated by a semiempirical method. This method is the generalization of the dielectric description theory of Phillips, Van Vechten, Levine and Tanaka scheme. The results indicate that larger valences usually result in higher bond covalencies, in good agreement with the point that the excess charge in the bonding region is the origin of formation of bond covalency. Other factors, such as oxidation state of elements, only make a small contribution to bond covalency.

Bond covalencies in R2BaCuO5 (R = Sm, Gd, Dy, Ho, Y, Er, Tm, Yb, Lu)

Bond covalencies in R2BaCuO5 (R = Sm, Gd, Dy, Ho, Y, Er, Tm, Yb, Lu) were calculated by means of a semiempirical method. This method is the generalization of the dielectric description theory of Phillips-Van Vechten-Levine-Tanaka scheme. The present paper presents the formula concerning the decomposing of complex crystals which are usually anisotropic systems into the sum of binary crystals which are isotropic systems. It can be seen that although the bond covalency is related to many physical quantities, it is mainly influenced by bond valence or bond charge, and a higher bond valence will produce higher bond covalency.

Semiempirical method for the evaluation of bond covalency in complex crystals

We report a semiempirical method for the evaluation of bond covalency in complex crystals. This method is the extension of the dielectric description theory delivered by Phillips, Van Vechten, Levine, and Tanaka (PVLT) which is mainly suitable for binary crystals. Our method offers the advantage of applicability to a broad class of complex materials. The simplicity of the approach allows a broader class of researchers to access the method easily and to calculate not only the bond covalency but also other useful. properties such as bulk modulus. For a series study, a useful trend can be illustrated and often the prediction of the properties of the-missing one(s) among the series can be possible. Finally, examples are given to show how the method is applied and the procedure is transferable to other complex crystals.

Calculation of chemical bond parameters in La1-xCaxCrO3 (0.0 <= x <= 0.3)

The chemical bond parameters, that is, bond covalency, bond susceptibility, and macroscopic linear susceptibility of La1-xCaxCrO3 (x = 0.0, 0.1, 0.2, 0.3) has been calculated using a semiempirical method. This method is the generalization of the dielectric description theory proposed by Phillips, Van Vechten, Levine, and Tanaka (PVLT). In the calculation of bond valence, two schemes were adopted. One is the bond valence sums (BVS) scheme, and the other is the equal-valence scheme. Both schemes suggest that for the title compounds bond covalency and bond susceptibility are mainly influenced by bond valence and are insensitive to the Ca doping level or structural change. Larger bond valences usually result in higher bond covalency and bond susceptibility. The macroscopic linear susceptibility increases (only slightly for BVS scheme) with the increasing Ca doping level. (C) 1999 John Wiley & Sons, Inc.

Influence of bond valence on bond covalency in calcium doped lanthanum chromite

The influence of bond valence on bond covalency in La1-xCaxCrO3(x =0.0, 0.1, 0.2, 0.3) has been studied by using semiempirical method. This method is the extension of the dielectric description theory proposed by Phillips, Van Vechten, levine and Tanaka (PVLT). In the calculation of bond valence, two schemes were adopted. The first is the equal-valence scheme, and the second is Bond Valence Sums (BVS) scheme. Both schemes suggest that for the title compound bond covalency be mainly influenced by bond valence, and insensitive to the Ca doping level. Generally speaking, larger bond valences usually result in higher bond covalencies.