A Spin - 3/2 Ising Model on a Square Lattice

The spin - 3/2 Ising model on a square lattice is investigated. It is shown that this model is reducible to an eight - vertex model on a surface in the parameter space spanned by coupling constants J, K, L and M. It is shown that this model is equivalent to an exactly solvable free fermion model along two lines in the parameter space.Comment: LaTeX, 7 pages, 1 figure upon request; JETP Letters, in pres

A Class of Exact Solutions of the Wheeler -- De Witt Equation

After carefully regularizing the Wheeler -- De Witt operator, which is the Hamiltonian operator of canonical quantum gravity, we find a class of exact solutions of the Wheeler -- De Witt equation.Comment: 9 pages, Latex, (one reference and one conclusion added, minor corrections in the formulae

Exact location of the multicritical point for finite-dimensional spin glasses: A conjecture

We present a conjecture on the exact location of the multicritical point in the phase diagram of spin glass models in finite dimensions. By generalizing our previous work, we combine duality and gauge symmetry for replicated random systems to derive formulas which make it possible to understand all the relevant available numerical results in a unified way. The method applies to non-self-dual lattices as well as to self dual cases, in the former case of which we derive a relation for a pair of values of multicritical points for mutually dual lattices. The examples include the +-J and Gaussian Ising spin glasses on the square, hexagonal and triangular lattices, the Potts and Z_q models with chiral randomness on these lattices, and the three-dimensional +-J Ising spin glass and the random plaquette gauge model.Comment: 27 pages, 3 figure

Critical phase of a magnetic hard hexagon model on triangular lattice

We introduce a magnetic hard hexagon model with two-body restrictions for configurations of hard hexagons and investigate its critical behavior by using Monte Carlo simulations and a finite size scaling method for discreate values of activity. It turns out that the restrictions bring about a critical phase which the usual hard hexagon model does not have. An upper and a lower critical value of the discrete activity for the critical phase of the newly proposed model are estimated as 4 and 6, respectively.Comment: 11 pages, 8 Postscript figures, uses revtex.st

Yield and Quality of Sugarcane as Affected by Phosphate Applied Cation on Soils of Various Phosphorus Levels

Effects of phosphate application on the growth, yield and quality of sugarcane (Saccharum officinarum L.) were studied on the soils having various phosphorus levels. Superphosphate was applied to bring the available soil P at 5, 15, 25 and 35 mg P2O5 100 g-1 designated as A, B, C and D levels, respectively. Leaf area index (LAI) and dry matter increased on the higher P plots over the lower P plots. The highest cane yield (74 t ha-1) and sugar yield (10.2 t ha- 1) were obtained from the B plot and the lowest cane yield (51 t ha-1) and sugar yield (6.9 t ha-1) were from the A plot. The D plot failed to give the highest cane and sugar yield due to lower millable canes accompanied with poor juice quality. Heavy P application showed bad effects on leaf quality by decreasing N, K, Zn and Cu contents

Linear Embedding-based High-dimensional Batch Bayesian Optimization without Reconstruction Mappings

The optimization of high-dimensional black-box functions is a challenging problem. When a low-dimensional linear embedding structure can be assumed, existing Bayesian optimization (BO) methods often transform the original problem into optimization in a low-dimensional space. They exploit the low-dimensional structure and reduce the computational burden. However, we reveal that this approach could be limited or inefficient in exploring the high-dimensional space mainly due to the biased reconstruction of the high-dimensional queries from the low-dimensional queries. In this paper, we investigate a simple alternative approach: tackling the problem in the original high-dimensional space using the information from the learned low-dimensional structure. We provide a theoretical analysis of the exploration ability. Furthermore, we show that our method is applicable to batch optimization problems with thousands of dimensions without any computational difficulty. We demonstrate the effectiveness of our method on high-dimensional benchmarks and a real-world function

Development of a New Type Personal Dosemeter with Silicon Detector

開始ページ、終了ページ: 冊子体のページ付

Naive mean field approximation for image restoration

We attempt image restoration in the framework of the Baysian inference. Recently, it has been shown that under a certain criterion the MAP (Maximum A Posterior) estimate, which corresponds to the minimization of energy, can be outperformed by the MPM (Maximizer of the Posterior Marginals) estimate, which is equivalent to a finite-temperature decoding method. Since a lot of computational time is needed for the MPM estimate to calculate the thermal averages, the mean field method, which is a deterministic algorithm, is often utilized to avoid this difficulty. We present a statistical-mechanical analysis of naive mean field approximation in the framework of image restoration. We compare our theoretical results with those of computer simulation, and investigate the potential of naive mean field approximation.Comment: 9 pages, 11 figure

Global Bethe lattice consideration of the spin-1 Ising model

The spin-1 Ising model with bilinear and biquadratic exchange interactions and single-ion crystal field is solved on the Bethe lattice using exact recursion equations. The general procedure of critical properties investigation is discussed and full set of phase diagrams are constructed for both positive and negative biquadratic couplings. In latter case we observe all remarkable features of the model, uncluding doubly-reentrant behavior and ferrimagnetic phase. A comparison with the results of other approximation schemes is done.Comment: Latex, 11 pages, 13 ps figures available upon reques

Monte Carlo Study of the Anisotropic Heisenberg Antiferromagnet on the Triangular Lattice

We report a Monte Carlo study of the classical antiferromagnetic Heisenberg model with easy axis anisotropy on the triangular lattice. Both the free energy cost for long wavelength spin waves as well as for the formation of free vortices are obtained from the spin stiffness and vorticity modulus respectively. Evidence for two distinct Kosterlitz-Thouless types of defect-mediated phase transitions at finite temperatures is presented.Comment: 8 pages, 10 figure