Geometrical Formulation of 3-D Space-Time Finite Integration Method

A geometrical formulation of a space-time finite-integration (FI) method is studied for application in electromagnetic-wave propagation calculations. Based on the Hodge duality and Lorentzian metric, a modified relation is derived between the incidence matrices of space-time primal and dual grids. A systematic method to construct the Maxwell grid equations on the space-time primal and dual grids is developed. The geometrical formulation is implemented on a simple space-time grid, which is proven equivalent to an explicit time-marching scheme of the space-time FI method

Analytical model for reduction of deep levels in SiC by thermal oxidation

Two trap-reduction processes, thermal oxidation and C+ implantation followed by Ar annealing, have been discovered, being effective ways for reducing the Z[1/2] center (EC – 0.67 eV), which is a lifetime killer in n-type 4H-SiC. In this study, it is shown that new deep levels are generated by the trap-reduction processes in parallel with the reduction of the Z[1/2] center. A comparison of defect behaviors (reduction, generation, and change of the depth profile) for the two trap-reduction processes shows that the reduction of deep levels by thermal oxidation can be explained by an interstitial diffusion model. Prediction of the defect distributions after oxidation was achieved by a numerical calculation based on a diffusion equation, in which interstitials generated at the SiO2/SiC interface diffuse to the SiC bulk and occupy vacancies related to the origin of the Z[1/2] center. The prediction based on the proposed analytical model is mostly valid for SiC after oxidation at any temperature, for any oxidation time, and any initial Z[1/2]-concentration. Based on the results, the authors experimentally achieved the elimination of the Z[1/2] center to a depth of about 90 μm in the sample with a relatively high initial-Z[1/2]-concentration of 10[13] cm[−3] by thermal oxidation at 1400 °C for 16.5 h. Furthermore, prediction of carrier lifetimes in SiC from the Z[1/2] profiles was realized through calculation based on a diffusion equation, which considers excited-carrier diffusion and recombination in the epilayer, in the substrate, and at the surface

Enumerating Graph Partitions Without Too Small Connected Components Using Zero-suppressed Binary and Ternary Decision Diagrams

Partitioning a graph into balanced components is important for several applications. For multi-objective problems, it is useful not only to find one solution but also to enumerate all the solutions with good values of objectives. However, there are a vast number of graph partitions in a graph, and thus it is difficult to enumerate desired graph partitions efficiently. In this paper, an algorithm to enumerate all the graph partitions such that all the weights of the connected components are at least a specified value is proposed. To deal with a large search space, we use zero-suppressed binary decision diagrams (ZDDs) to represent sets of graph partitions and we design a new algorithm based on frontier-based search, which is a framework to directly construct a ZDD. Our algorithm utilizes not only ZDDs but also ternary decision diagrams (TDDs) and realizes an operation which seems difficult to be designed only by ZDDs. Experimental results show that the proposed algorithm runs up to tens of times faster than an existing state-of-the-art algorithm

High temperature expansion in supersymmetric matrix quantum mechanics

We formulate the high temperature expansion in supersymmetric matrix quantum mechanics with 4, 8 and 16 supercharges. The models can be obtained by dimensionally reducing N=1 U(N) super Yang-Mills theory in D=4,6,10 to 1 dimension, respectively. While the non-zero frequency modes become weakly coupled at high temperature, the zero modes remain strongly coupled. We find, however, that the integration over the zero modes that remains after integrating out all the non-zero modes perturbatively, reduces to the evaluation of connected Green's functions in the bosonic IKKT model. We perform Monte Carlo simulation to compute these Green's functions, which are then used to obtain the coefficients of the high temperature expansion for various quantities up to the next-leading order. Our results nicely reproduce the asymptotic behaviors of the recent simulation results at finite temperature. In particular, the fermionic matrices, which decouple at the leading order, give rise to substantial effects at the next-leading order, reflecting finite temperature behaviors qualitatively different from the corresponding models without fermions.Comment: 17 pages, 13 figures, (v2) some typos correcte

Діалогічне педагогічне спілкування як основа суб’єкт-суб’єктної взаємодії

(uk) У статті автор характеризує процес педагогічного спілкування з позицій діалогічності, визначаючи це як умову забезпечення суб’єкт-суб’єктних стосунків.(ru) В статье автор характеризует процесс педагогического общения из позиций диалогичности, определяя это как условие обеспечения субъект-субъектных отношений