We consider preconditioned Krylov subspace methods for solving large sparse linear systems under the assumption that the coefficient matrix is a (possibly singular) M -matrix. The matrices are partitioned into 2×2 block form using graph partitioning. Approximations to the Schur complement are used to produce various preconditioners of block triangular and block diagonal type. A few properties o...

An orange carotenoid from Micrococcus roseus was purified by solvent partitioning followed by column and thin-layer chromatography. Absorption spectra, chromatographic mobility, and partition coefficient suggested that the pigment was echinenone (4-keto-beta-carotene). Reduction yielded a pigment with the spectral and polar properties of isocryptoxanthin (4-hydroxy-beta-carotene), the expected ...

Among all wavelet transform and zero-tree quantization based image coding algorithms, set partitioning in hierarchical trees (SPIHT) is well known for its simplicity and efficiency. But theoretical analysis and experimental results have shown there are still some key points need to be further improved. This paper proposes a coefficient Statistic based Modified SPIHT Lossless Image Compression A...

We investigate the usage of Ant Colony Optimization to detect balanced graph cuts. In order to do so we develop an algorithm based on competing ant colonies. We use a heuristic from social network analysis called the edge clustering coefficient, which greatly helps our colonies in local search. The algorithm is able to detect cuts that correspond very well to known cuts on small real-world netw...

Abstract— In this paper the Hopfield neural networks are adopted to solve the quadratic assignment problem, which is a generalization of the traveling salesman’s problem (TSP), the graph-partitioning problem (GPP), and the matching problem. When the Hopfield neural network was applied alone, a sub-optimal solution was obtained. By adding the 2exchange we obtained a solution very close to the op...

Iterative solver with preconditioning is the most powerful choice for large-scale scientific computation, especially for the parallel computing. In nonlinear problems such as contact simulations for geophysics, the condition numbers of the coefficient matrices are usually large due to special constraint conditions. The result is slow convergence of the iterative solver. In this study, a new pre...

is said to be of order n and weight &1+&2+ • • • + a n . Since ax* = x*+ • • • +^ 4 , to ^ terms, a form of weight w is equal to a sum of w biquadrates. But 79 is not a sum of fewer than nineteen biquadrates. Hence 19 is the minimum weight of a form (1) which represents all positive integers. Let ƒ be a form (1) which represents p, and let ai = r+s. The form g = (r, s, a2, • • • , an) shall be ...

This paper provides new delay-range-dependent stability criteria in the forms of LMIs for systems with interval time-varying delays. Two cases concerning whether the derivative of the time delay is known are studied. A new estimation method is developed to estimate the nonlinear time-varying coefficients derived from Jenson’s integral inequality more tightly than the existing ones. Along with c...

The following paper introduces a low bitrate video coding method on the basis of 3D motion compensated wavelet transform and SPIHT algorithm. In contrast to the conventional algorithms applying motion compensation and differential coding, here wavelet transform is used to exploit the opportunities of time redundancy. For coefficient collection, the 3D version of SPIHT algorithm was selected fro...