The short-time Dynamics of the Critical Potts Model

The universal behaviour of the short-time dynamics of the three state Potts model in two dimensions at criticality is investigated with Monte Carlo methods. The initial increase of the order is observed. The new dynamic exponent $\theta$ as well as exponent $z$ and $\beta/\nu$ are determined. The measurements are carried out in the very beginning of the time evolution. The spatial correlation length is found to be very short compared with the lattice size.Comment: 6 pages, 3 figure

Determination of the Critical Point and Exponents from short-time Dynamics

The dynamic process for the two dimensional three state Potts model in the critical domain is simulated by the Monte Carlo method. It is shown that the critical point can rigorously be located from the universal short-time behaviour. This makes it possible to investigate critical dynamics independently of the equilibrium state. From the power law behaviour of the magnetization the exponents $\beta / (\nu z)$ and $1/ (\nu z)$ are determined.Comment: 6 pages, 4 figure

Estimation of depth fields suitable for video compression using 3-D structures and motion of objects

Cataloged from PDF version of article.Intensity prediction along motion trajectories removes temporal redundancy considerably in video compression algorithms. In threedimensional (3-D) object-based video coding, both 3-D motion and depth values are required for temporal prediction. The required 3-D motion parameters for each object are found by the correspondence-based Ematrix method. The estimation of the correspondences—two-dimensional (2-D) motion field—between the frames and segmentation of the scene into objects are achieved simultaneously by minimizing a Gibbs energy. The depth field is estimated by jointly minimizing a defined distortion and bitrate criterion using the 3-D motion parameters. The resulting depth field is efficient in the rate-distortion sense. Bit-rate values corresponding to the lossless encoding of the resultant depth fields are obtained using predictive coding; prediction errors are encoded by a Lempel–Ziv algorithm. The results are satisfactory for real-life video scenes

3-D motion estimation of rigid objects for video coding applications using an improved iterative version of the E-matrix method

Cataloged from PDF version of article.As an alternative to current two-dimensional (2-D) motion models, a robust three-dimensional (3-D) motion estimation method is proposed to be utilized in object-based video coding applications. Since the popular E-matrix method is well known for its susceptibility to input errors, a performance indicator, which tests the validity of the estimated 3-D motion parameters both explicitly and implicitly, is defined. This indicator is utilized within the RANSAC method to obtain a robust set of 2-D motion correspondences which leads to better 3-D motion parameters for each object. The experimental results support the superiority of the proposed method over direct application of the E-matrix method

Infrared and Raman Spectroscopic Characterization of Porphyrin and its Derivatives

Density functional theory (DFT) was employed to investigate protonation, deuteration, and substitution effects on the vibrational spectra of porphyrin molecules. The results of the calculations were compared with experimental data. The calculations show that meso‐substitutions produced a substantial shift in frequencies when the meso‐carbons within the parent porphine are involved in the vibrational motion of molecules, while protonation of the N atoms leads to a significant blue shift when the H atoms covalent bonded to the N atoms that are substantially involved in the vibrational motion. Deuteration of N atoms at the porphyrin core is found to result not only in a red shift in the frequencies of the corresponding peaks below 1600 cm-1, but also to generate new Raman bands of frequencies in the range of 2565–2595 cm-1, resulting from N‐D bond stretching. Also, the deuteration of O atoms within the sulfonato groups (‐SO3-) results in a new peak at near 2642 cm-1 due to O‐D bond stretching. Calculated IR spectra of the compounds studied here showed similar differences. Finally, we discuss solvent effects on the IR spectrum of TSPP

Isotropic three-dimensional left-handed meta-materials

We investigate three-dimensional left-handed and related meta-materials based on a fully symmetric multi-gap single-ring SRR design and crossing continuous wires. We demonstrate isotropic transmission properties of a SRR-only meta-material and the corresponding left-handed material which possesses a negative effective index of refraction due to simultaneously negative effective permeability and permittivity. Minor deviations from complete isotropy are due to the finite thickness of the meta-material.Comment: 4 pages, 6 figure

Geometric and Electronic Properties of Porphyrin and its Derivatives

In this chapter, we discuss protonation and substitution effects on the absorption spectra of porphyrin molecules based on density functional theory (DFT) and time-dependent DFT calculations. The results of the calculations are compared with experimental data. The calculations show that protonation of core nitrogen atoms of porphyrin and meso-substituted porphyrins produces a substantial shift in Soret and Q-absorption bands, relative to their positions in corresponding nonprotonated and nonsubstituted chromophores. A relaxed potential energy surface (RPES) scan has been utilized to calculate ground and excited state potential energy surface (PES) curves as functions of the rotation of one of the meso-substituted sulfonatophenyl groups about dihedral angles θ (corresponding to Cα─Cm─Cϕ─C) ranging from 40 to 130°, using 10° increments. The ground state RPES curve indicates that when the molecule transitions from the lowest ground state to a local state, the calculated highest potential energy barrier at the dihedral angle of 90° is only 177 cm−1. This finding suggests that the meso-sulfonatophenyl substitution groups are able to rotate around Cm─Cϕ bond at room temperature because the thermal energy (kBT) at 298 K is 207.2 cm−1. Furthermore, the calculations show that the geometric structure of the porphyrin is strongly dependent on protonation and the nature of the meso-substituted functional groups