Model simulation of parametrically excited ship rolling

Two different models for simulating the ship motion in longitudinal or oblique seas are presented and studied in detail. Particular attention is devoted to the parametrically induced rolling which may be established by means of the nonlinear coupling between both heave-roll and/or pitch-roll motions. It is proved that the phenomenon is likely to occur with this mechanism when the roll frequency is subharmonic of the encounter wave frequency and when the vertical motions become resonant.     

Linear bound on extremal functions of some forbidden patterns in 0-1 matrices

In this note by saying that a 0-1 matrix A avoids a pattern P given as a 0-1 matrix we mean that no submatrix of A either equals P or can be transformed into P by replacing some 1 entries with 0 entries. We present a new method for estimating the maximal number of the 1 entries in a matrix that avoids a certain pattern. Applying this method we give a linear bound on the maximal number of the 1 entries in an n by n matrix avoiding pattern L₁ and thereby we answer the question that was asked by Gábor Tardos. Furthermore, we use our approach on patterns related to L₁.     

Simultaneous effect of silica fume,metakaolin and ground granulated blast-furnace slag on the hydration of multicomponent cementitious binders

Portland cement was partially replaced by metakaolin (MK), silica fume (SF) and ground granulated blast-furnace slag (BFS). Globally, two amounts of SF (5 and 10 mass%) and total substitution level of 35 mass% were used to prepare blended samples. Their early and 28 days hydration was studied by means of isothermal calorimetry and thermal analysis. Developed phase composition was assessed using compressive strength measurements. Acceleration of cement hydration in early times was proved and reflected higher amounts of finer additives. Despite dilution effect, the presence of more reactive SF and MK resulted in pozzolanic reactions manifesting already before 2 days of curing and contributing to the formation of strength possessing phases. The influence of BFS addition showed later and thanks to the synergic effect of all the used additives; it was possible to increase its content up to 25 mass% by keeping the compressive strength values near that of referential one.

     

Asymmetric reduction of ketones with recombinant E. coli whole cells in neat substrates

The asymmetric reduction of ketones is performed by using lyophilized whole cells in neat substrates with defined water activity (a(w)). Ketones and alcohols prone to be unstable in aqueous media can now be converted via biocatalysis.     

Diameter bounds for planar graphs

The inverse degree of a graph is the sum of the reciprocals of the degrees of its vertices. We prove that in any connected planar graph, the diameter is at most 5/2 times the inverse degree, and that this ratio is tight. To develop a crucial surgery method, we begin by proving the simpler related upper bounds (4(|V|−1)−|E|)/3 and 4|V|²/3|E| on the diameter (for connected planar graphs), which are also tight.     

Distance bounds for algebraic geometric codes

Various methods have been used to obtain improvements of the Goppa lower bound for the minimum distance of an algebraic geometric code. The main methods divide into two categories, and all but a few of the known bounds are special cases of either the Lundell-McCullough floor bound or the Beelen order bound. The exceptions are recent improvements of the floor bound by Güneri, Stichtenoth, and Taskin, and by Duursma and Park, and of the order bound by Duursma and Park, and by Duursma and Kirov. In this paper, we provide short proofs for all floor bounds and most order bounds in the setting of the van Lint and Wilson AB method. Moreover, we formulate unifying theorems for order bounds and formulate the DP and DK order bounds as natural but different generalizations of the Feng-Rao bound for one-point codes.     

Torsion and Ortho-Slender Classes

This paper generalizes a number of results obtained by Dimitrić in (Glas. Mat. 21(41):327–329, 1986; Proceedings of Hobart Conference on Rings, Modules and Radicals 1987, 204:41–50, Gordon and Breach, 1989) and Dimitrić and Goldsmith in (Glas. Mat. 23(43):241–246, 1988). The original papers were restricted to the category of Abelian groups and orthogonality was to the group of integers ℤ. Here, we are in a general Abelian category with products and coproducts, with applications to module categories and further to modules over PID’s. Another generalization is in replacing ℤ by an entire class of subobjects of the underlying category. We examine properties of the torsion class , Hom(T,C)=0} in relation to purity, direct summands and indecomposability as well as commutation with direct products, for example. Of special interest are members of this class when is a class of slender objects in the ground category; in this case, members of are called ortho-slender objects. In a sense, ortho-slenderness represents complementary, if not dual, notion to slenderness.      

Study of the Calix[4]resorcinarene--dopamine interactions in monolayers by measurement of pressure--area isotherms and Maxwell displacement currents

The mechanisms of interactions between calix[4]resorcinarene and dopamine in monolayers formed at the air-water interface were studied by analyzing their mechanical, thermodynamic, and electrical properties evaluated from measurements of pressure-area isotherms and Maxwell displacement currents (MDCs). An increased concentration of dopamine in the water subphase resulted in an increase in the area per calix[4]resorcinarene molecule, an increase in the collapse pressure, and a shift in the monolayer phase transitions from the gaseous to the liquid state and from the liquid to the solid state toward higher molecular areas. A contactless method of recording MDCs enabled the monitoring of changes in the charge state of the monolayer-constituting molecules and the determination of a relationship between the phase state of the monolayer and the structural transitions of calix[4]resorcinarene. The changes of the MDC recordings started already in the gaseous state of the monolayer. On the basis of MDC values, we determined the normal component of the dipole moment of calix[4]resorcinarene, as well as that of its complex with dopamine. The dipole moment reached a maximum value of 1040 mD in the region of the phase transition from the liquid to the solid state of the monolayer. The results obtained suggest that the binding of dopamine with calix[4]resorcinarene depends on the orientation of the calixarene molecules in the monolayer. The calix[4]resorcinarene-dopamine interactions were also quantified in terms of the excess of Gibbs free energy, thereby allowing the evaluation of the energy of the calix [4]resorcinarene-dopamine bond, which was in the range from 1.95 to 8.54 kJ/mol depending on the surface pressure. This value implies weak interactions between these molecules.     

Synthesis and characterization of platinum monolayer oxygen-reduction electrocatalysts with Co–Pd core–shell nanoparticle supports

We synthesized Pt monolayer electrocatalysts for oxygen-reduction using a new method to obtain the supporting core–shell nanoparticles. They consist of a Pt monolayer deposited on carbon-supported Co–Pd core–shell nanoparticles with the diameter of 3–4 nm. The nanoparticles were made using a redox-transmetalation (electroless deposition) method involving the oxidation of Co by Pd cations, yielding a Pd shell around the Co core. The quality of the thus-formed core–shell structure was verified using transmission electron microscopy and X-ray absorption spectroscopy, while cyclic voltammetry was employed to confirm the lack of Co oxidation (dissolution). A Pt monolayer was deposited on the Co–Pd core–shell nanoparticles by the galvanic displacement of a Cu monolayer obtained by underpotential deposition. The total noble metal mass-specific activity of this Pt monolayer electrocatalyst was ca. 3-fold higher than that of commercial Pt/C electrocatalysts.