Image quality assessment metrics by using directional projection

Objective image quality mcasure, which is a fundamental and challenging job in image processing, evaluates the image quality consistently with human perception automatically. On the assumption that any image distortion could be modeled as the difference between the directional projection-based maps of reference and distortion images, wc propose a new objective quality assessment method based on directional projection for full reference model. Experimental results show that the proposed metrics are well consistent with the subjective quality score.     

Generation of 40 GHz and 60 GHz Optical Pulses by Repetition Rate Multiplying with Comb-like Filter

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｇｅｎｅｒａｔｉｏｎｏｆｏｐｔｉｃａｌ ｐｕｌｓｅｓｗｉｔｈｈｉｇｈｒｅｐｅｔｉｔｉｏｎｒａｔｅｉｓｏｎｅｏｆｔｈｅｋｅｙｔｅｃｈｎｏｌｏｇｉｅｓｉｎｔｈｅｆｕｔｕｒｅｕｌｔｒａ ｈｉｇｈｓｐｅｅｄｏｐｔｉｃａｌｎｅｔｗｏｒｋｓ[1] .Ｉｔｉｓａｌｓｏｕｓｅｆｕｌｆｏｒｇｅｎｅｒａｔｉｏｎｏｆｏｐｔｉｃａｌｌｙ ｆｅｄｍｉｌｌｉｍｅｔｅｒｗａｖｅｉｎｆｉｂｅｒ ｒａｄｉｏｔｒａｎｓｍｉｓｓｉｏｎ[2～ 4] .Ａｌｔｈｏｕｇｈｔｈｅｂａｎｄｗｉｄｔｈｏｆｅｌｅｃｔｒｏｎｉｃａｎ…     

FIR Photonic Microwave Filter Design Employing Simulated Annealing Algorithm

Photonic microwave filters are important parts of fiberoptic microwave/millimeter wave processing systems. In this paper, the synthesis problem of fiberoptic FIR microwave filters is addressed and a novel method for designing photonic microwave filter employing a simulated annealing (SA) algorithm is proposed. The design problem of photonic microwave filter can be reduced to be a multivariable function optimization problem, which can be solved by a simulated annealingbased algorithm. As an illustration of the application of SA to photonic microwave filter design, the synthesis of an optimizedFBGbased photonic microwave filter is discussed. Numerical results show that the global minimum finding capability of SA makes it be an efficient way to design the photonic microwave filter. Numerical results also demonstrate that the proposed method can be applied to design different filtering systems with different constraints.     

Design of Header Recognition Filter for Binary Phase Shift Keying in Header Recognition Unit using Time-Space Conversion

Optical header recognition is one key function that enables ultrafast optical routing in photonic packet-switched networks. Especially, optical header recognition based on optical correlation processing has attracted much attention. Header signals using optical codes are decoded using optical correlation processing. We improve the decoding method for Binary Phase Shift Keying (BPSK) header signals in order to suppress crosstalk caused by matched filtering in the header recognition unit. We design a header recognition filter using the technique of a multiple-object discriminant filter (MODF). Results of preliminary experiments show that the designed header recognition filter can suppress crosstalk. The intensity ratio of correlation signals of a target header signal to non-target ones is higher than 1.95 : 1 in case of 4-bits BPSK header signals.     

Separation of Optical Modes in a Coupler on the Basis of the Bragg One-Dimensional Grating

An integrated narrow-band filter for a wavelength of 1.5 m based on the Bragg Si/SiO₂ one-dimensional grating coupled to a standard waveguide has been designed. Vector simulation of the dispersion properties and calculation of the operational characteristics of the filter using the method of matching in conjugation with the theory of supermodes were carried out. The full width at the half-maximum level (FWHM) of the transmission spectrum gives the subnanometer range at a filter length of about 1 mm.     

Optimal value functions of generalized semi-infinite min-max programming on a noncompact set

In this paper, we study optimal value functions of generalized semi-infinite min-max programming problems on a noncompact set. Directional derivatives and subd-ifferential characterizations of optimal value functions are given. Using these properties, we establish first order optimality conditions for unconstrained generalized semi-infinite programming problems.     

Algebraic description of spin 3/2 dynamics in NMR experiments

The dynamics of spin 3/2 systems is analyzed using the density matrix theory of relaxation. By using the superoperator formalism, an algebraic formulation of the density matrix's evolution is obtained, in which the contributions from free relaxation and RF application are easily factored out. As an intermediate step, an exact form for the propagator of the density matrix for a spin 3/2 system, in the presence of static quadrupolar coupling, inhomogeneous static magnetic field, and relaxation is demonstrated. Using this algebraic formulation, exact expressions for the behavior of the density matrix in the classical one-, two-, and three-pulse experiments are derived. These theoretical formulas are then used to illustrate the bias introduced on the measured relaxation parameters by the presence of large spatial variations in the B0 and B1 fields. The theoretical predictions are easily evaluated through simple matrix algebra and the results agree very well with the experimental observations. This approach could prove useful for the characterization of the spatial variations of the signal intensity in multiple quantum-filtered sodium MRI experiments.     

Triple-quantum-filtered imaging of sodium in presence of B(0) inhomogeneities

Triple quantum filtered sodium MRI techniques have been recently demonstrated in vivo. These techniques have been previously advocated as a means to separate the sodium NMR signal from different physiological compartments based on the differences between their relaxation rates. Among the different triple quantum coherence transfer filters, the three-pulse coherence transfer filter has been demonstrated to be better suited for human imaging than the traditional four-pulse implementation. While the three-pulse structure has distinct advantages in terms of RF efficiency, the lack of a refocusing pulse in the filter introduces an increased dependence on the main magnetic field inhomogeneities, which can sometimes lead to significant signal loss. In this paper, we characterize these dependencies and introduce a method for their compensation through the acquisition of a B(0) map and the use of a modified phase cycling scheme.     

Regularization of the two-dimensional filter diagonalization method: FDM2K

We outline an important advance in the problem of obtaining a two-dimensional (2D) line list of the most prominent features in a 2D high-resolution NMR spectrum in the presence of noise, when using the Filter Diagonalization Method (FDM) to sidestep limitations of conventional FFT processing. Although respectable absorption-mode spectra have been obtained previously by the artifice of “averaging” several FDM calculations, no 2D line list could be directly obtained from the averaged spectrum, and each calculation produced numerical artifacts that were demonstrably inconsistent with the measured data, but which could not be removed a posteriori. By regularizing the intrinsically ill-defined generalized eigenvalue problem that FDM poses, in a particular quite plausible way, features that are weak or stem from numerical problems are attenuated, allowing better characterization of the dominant spectral features. We call the new algorithm FDM2K.     

The Theory of Local Homology for Artinian Modules

In this paper, the theory of local homology for Artinian modules is developed, which in some aspect is similar to the theory of local cohomology. There are given some criteria for local homology modules to be good and dual of the ideal transform functor is studied.AMS Subject Classification (1991): 13E10 13D45