Non-uniform Partitioning Research Articles

An Improved Algorithm of Keyframe Extraction for Video Summarization

Video segmentation and keyframe extraction are the basis of Content-based Video Retrieval (CBVR), in which keyframe selection plays the central role in CBVR. In this paper, as the initialization of keyframe extraction, we proposed an improved approach of key-frame extraction for video summarization. In our approach, videos were firstly segmented into shots according to video content, by our improved histogram-based method, with the use of histogram intersection and nonuniform partitioning and weighting. Then, within each shot, keyframes were determined with the calculation of image entropy as a reflection of the quantity of image information in HSV color space of every frame. Our simulation results in section 4 prove that extracted key frames with our method are compact and faithful to the original video.

Delay-dependent stability criteria for interval time-varying delay systems with nonuniform delay partitioning approach

This paper investigates the conservatism reduction of Lyapunov-Krasovskii based conditions for the stability of a class of interval time-varying delay systems. The main idea is based on the nonuniform decomposition of the integral terms of the Lyapunov-Krasovskii functional. The delay interval is decomposed into a finite number of nonuniform segments with some scaling parameters. Both differentiable delay case and nondifferentiable delay case and unknown delay derivative bound case are taken into consideration. Sufficient delay-dependent stability criteria are derived in terms of matrix inequalities. Two suboptimal delay fractionation schemes, namely, linearization with cone complementary technique and linearization under additional constraints are introduced in order to find a feasible solution set using LMI solvers with a convex optimization algorithm so that a suboptimal maximum allowable delay upper bound is achieved. It is theoretically demonstrated that the proposed technique has reduced complexity in comparison to some existing delay fractionation methods from the literature. A numerical example with case studies is given to demonstrate the effectiveness of the proposed method with respect to some existing ones from the literature.

A coupled EBSD/EDS method to determine the primary- and secondary-alpha textures in titanium alloys with duplex microstructures

A method for separating the textures of primary alpha (αp) and secondary alpha (αs) in alpha/beta titanium alloys with a duplex microstructure was developed. Utilizing electron backscatter diffraction (EBSD) and energy-dispersive spectroscopy (EDS), the approach relies on the non-uniform partitioning of alloying elements between primary alpha and regions containing secondary-alpha lamellae and residual beta matrix phase. The method was evaluated using samples of Ti–6Al–4V for which vanadium partitions strongly to secondary alpha+beta regions. The technique thus provides a useful tool for quantifying the evolution of deformation texture in the primary alpha and transformation texture in secondary alpha formed via decomposition of the beta matrix following hot working or final heat treatment.

Fluid flow through ramified structures.

We investigate the fluid flow through two-dimensional ramified structures by direct simulation of the Navier-Stokes equations. We show that for trees with n generations, the flow distribution strongly depends on the Reynolds number Re. Specifically, for a tree without loops the flow becomes highly heterogeneous at high Re. For a tree with loops, on the other hand, the flow distribution tends to be more uniform at increased Re conditions. We show that these apparently contradictory behaviors have the same origin, namely, the effect of inertia on the momentum transport in the channels of the ramified geometry. In order to simulate the propagation of the flow imbalance throughout the tree without loops, we develop a simple model that incorporates the basic fluid dynamics features of the system. For large trees, the results of the model indicate that the distribution of flow at the outlet branches can be described by a self-affine landscape. Finally, we argue that the nonuniform partitioning of flow found for the structure without loops may contribute to the morphogenesis and functioning of the bronchial tree.

Experimental factors governing the internal stress state of the intervertebral disc

This paper presents an experimental study of the response of the intervertebral disc to short-term static-axial loading within the conceptual framework of mechanical consolidation as applied to swelling materials. An experimental technique developed previously for articular cartilage was used to load the disc in compression and measure simultaneously the matrix internal excess pore pressure under both radially constrained and radially unconstrained conditions. Specifically the short-term pattern of development of the hydrostatic excess pore pressure was investigated. The average ratio of the maximum excess pore pressure u i to the nominal applied stress for unconstrained loading was approximately 1.9 while for constrained loading it was about 1.4. This behaviour is interpreted in terms of the generation of a pore pressure in the nucleus which reflects a non-uniform partitioning of the applied load across the inhomogeneous structure of the disc. These results provide a quantitative insight into the role that physico-chemically generated swelling plays in determining the internal mechanical response of the disc to an externally applied load and suggest a quantitative means of investigating the important influence of degenerative changes on the internal stress state of the disc without needing to pierce the annular wall in order to insert a pressure sensing device.

A new method for efficient convolution in frequency domain by nonuniform partitioning for adaptive filtering

By using block processing, partitioning, and fast Fourier transforms (FFTs), large filters perform efficiently in the frequency domain. For small processing delay the complexity can still be too large for implementation on a digital signal processor (DSP). A solution is to partition the filter into unequal-length subfilters. Application in adaptive filtering yields the nonuniform partitioned block frequency domain adaptive filter (NU-PBFDAF).

Salt partitioning in Winsor Type II systems

In systems in which an excess aqueous phase is in equilibrium with a micellar solution, so-called microemulsion, i.e., Type II in Winsor's nomenclature, a nonuniform partitioning of sodium chloride has been observed. This partitioning has been investigated under a variety of surfactant and salt concentrations with both nonionic and anionic surfactants. In both cases, the salt concentration in the excess brine phase has been found higher than in the brine contained in the micellar phase. The magnitude of the effect is, however, lower in the case of nonionics. With nonionic surfactants, the results are interpreted by considering that some salt-free water molecules in the micellar phase are devoted to hydrate the surfactant heads; in the remaining water of the micellar phase, the salt concentration is assumed identical to that in the excess aqueous phase. With anionic surfactant, beside the hydration of the polar heads by some salt-free water molecules, the partial surfactant ionization has also to be taken into account through a dissociation constant. For both systems, despite the large variety of experimental conditions, the calculated excess aqueous phase salinities are found to agree well with the experimental results.

Flow partitioning in symmetric cascades of branches.

We have found markedly nonuniform partitioning of flow in idealized models of physiological cascades of branches. Liquids having viscosities of 0.8-7.0 cP were used to investigate this effect systematically in a regime characterizing a limited range of pulmonary flows, comprising inlet flow rates of 500-3,000 ml/min and branch diameters of 1.0 cm ID. Factors that affect the nonuniformity of inspiratory flow include inlet velocity profile and flow rate, cascade aspect (L/D) ratio, exit pressure distribution, and, to a lesser extent, kinematic viscosity (mu/rho). More qualitative observations using sinusoidally oscillating airflow revealed inspiratory and expiratory flow patterns to be quite dissimilar, emphasizing the inadequacy of a resistance model of flow partitioning based on Kirchhoff's law. These results might suggest, in part, why regional ventilation in man is flow or frequency dependent and how bronchial smooth muscle could fine tune regional ventilation.