A symmetric matrix is called copositive if it generates a quadratic form taking no negative values over the nonnegative orthant, and the linear optimization problem over the set of copositive matrices is called the copositive programming problem. Recently, many studies have been done on the copositive programming problem (see, for example, [14, 5]). Among others, several branch and bound type a...

We discuss the computational complexity of several problems concerning subsets of an algebraic structure that generate the structure. We show that the problem of determining whether a given subset X generates an algebra A is P-complete, while determining the size of the smallest generating set is NP-complete. We also consider several questions related to the Frattini subuniverse, Φ(A), of an al...

the kinetic of fischer-tropsch synthesis over a co-precipitated fe-ce catalyst was investigated in a fixed bed micro reactor. experimental conditions were varied as follow: reaction pressure 1-15bar, h¬¬¬2/co feed ratio of 1-3 and space velocity of 3600-5400 h-1 at the temperature range of 270-310°c. 4 models according to the langmuir-hinshelwood-hougen-watson (lhhw) type rate equation were der...

we present a steganalysis scheme for lsb matching steganography based on feature vectors extracted from integer wavelet transform (iwt). in integer wavelet decomposition of an image, the coefficients will be integer, so we can calculate co-occurrence matrix of them without rounding the coefficients. before calculation of co-occurrence matrices, we clip some of the most significant bitplanes of ...

Given an H-polytope P and a V-polytope Q, the decision problem whether P is contained in Q is co-NP-complete. This hardness remains if P is restricted to be a standard cube and Q is restricted to be the affine image of a cross polytope. While this hardness classification by Freund and Orlin dates back to 1985, there seems to be only limited progress on that problem so far. Here, we study the H-...

For a linear code, deep holes are defined to be vectors that are further away from codewords than all other vectors. The problem of deciding whether a received word is a deep hole for generalized ReedSolomon codes is proved to be co-NP-complete [9][5]. For the extended Reed-Solomon codes RSq(Fq, k), a conjecture was made to classify deep holes in [5]. Since then a lot of effort has been made to...

The syntheses of Co(eta3-C3H5)(CO)2PR2R' (R, R' = Ph, Me; R, R' = Me, Ph; R = R' = Ph, Cy, CH2Ph) and Co(eta3-C3H5)(CO)(L) (L = dmpe and dppe) are described, and X-ray structures for Co(eta3-C3H5)(CO)(dppe) and the PPh2Me, PCy3 derivatives reported. The relative ability of Co(eta3-C3H5)(CO)2(PR2R') to exchange phosphine for CO follows the trend PMe2Ph < PPh2Me < PCy3 < P(CH2Ph)3 < PPh3. Reactio...

Optoelectronic properties of hematite (α-Fe2O3) as a photoanode and the required over-potential in photo-assisted water splitting has been improved by presence of Co-Pi on its surface. In order to increase the lifetime of the photogenerated holes and lower the applied bias, cobalt-phosphate (Co-Pi) on nanostructured α-Fe2O3 by electrodeposition was de...

In this work, the dry reforming of methane was studied using a corona and gliding discharge plasma microreactors. A chemical kinetic model was developed to describe the experimental behavior observed. The kinetic model is proposed based on the assumption that the reactant molecules CH4 or CO2 are attacked by active species produced b...

several factors effect on sorption of polycyclic aromatic hydrocarbons (pahs) in soil. co-existence of metals and organic matter of soil are among important affecting factors on sorptive behavior of pahs. this research investigated the effect of organic matter content and heavy metals (lead, nickel and zinc), on sorption of phenanthrene onto kaolinite. for this purpose, sorption of the organic ...