‘Doing the right problem’ <Emphasis Type="Italic">versus</Emphasis> ‘doing the problem right’: problem structuring within a Land Force environment

The essential first step of any OR investigation is to ensure that the ‘right problem’ is studied. Our approach is to propose a set of six ‘rights’ or questions whereby achievement against particular aspects of a problem space is made and these provide the basis for scoping the context, understanding the system, and proposing sound options to the decision-maker. This style of problem structuring is an essential element of the Defence problem domain, and especially so for the Land Force, where there exist multiple degrees of freedom for poorly defined problems in an environment of uncertainty and ambiguity. Central to this is performing conceptual rather than analytical modelling, as perturbations then provide a basis for exploring a space, rather than solving a problem.     

Correlation between luminescent properties and structure organization in AlGaN/GaN superlattices annealed after erbium ion implantation

The evolution of the structure organization of MOCVD-grown AlGaN/GaN superlattices subjected to erbium ion implantation with an energy of 1 MeV and dose of 3 × 10¹⁵ cm^?2 and subsequent annealing is correlated with their photoluminescent properties. The structure organization is quantitatively estimated using parameter Δ (degree of violation of local symmetry), which is found via multifractal analysis of surface morphology patterns obtained with atomic force microscopy. It is shown that the implantation not only causes Ga segregation on the surface, but also changes the structure organization, which shows up in the finer grain structure compared with the starting one and disordering, as well as in an increase in Δ. As the annealing temperature rises from 700 to 800°C, Δ declines, indicating that the structure organization is improved, and the intensity of the dominating photoluminescence peak due to Er³⁺ ions (1.542 μm) grows. With a further increase in the annealing temperature to 1050°C, the structure organization degrades, domains get larger, voids 100–200 nm deep form, and the photoluminescence intensity drops. The formation of voids during high-temperature annealing is also substantiated by data for 230-keV proton scattering. It is thus established that the improvement of the superlattice structure organization activates erbium and causes the erbium-ion-related luminescence intensity to grow.     

Electrodeposition of molybdenum oxide and its structural characteristics

The cathodic processes in electroplating of compact molybdenum oxide coatings onto supports made of 12Cr18Ni9Ti steel and aluminum are considered along with the physicochemical characteristics determining their service properties.     

Bis(2-hydroxyacetophenone)ethylenediimine as a neutral carrier in a coated-wire membrane electrode for lead(II).

A coated-wire ion-selective electrode (CWISE), based on a Schiff base as a neutral carrier, was successfully developed for the detection of Pb(II) in aqueous solution. CWISE exhibited a linear response with a Nernstian slope of 29.4 +/- 0.5 mV/decade within the concentration range of 1.0 x 10(-5) - 1.0 x 10(-1) M lead ion. CWISE has shown detection limits of 5.0 x 10(-6) M. The electrode exhibited good selectivity over a number of alkali, alkaline earth, transition and heavy metal ions. This sensor yielded a steady potential within 10 to 20 s at a linear dynamic range. The electrode was suitable for use in aqueous solutions in a pH range of 2.0 to 5.0. Applications of this electrode for the determination of lead in real samples and as indicator electrode for potentiometric titration of Pb2+ ion using K2CrO4 are reported.     

Synthetic modeling of the active site of native metalloenzymes by trimethylacetatozinc complexes

Synthetic approaches are discussed to a preparation of binuclear trimethylacetatozinc complexes containing an M₂(μ-OOCR)₂L₄ binuclear fragment, which is found in the active site of native metalloenzymes.     

The standard enthalpies of formation of nitro compounds with small rings

The energies of combustion and standard enthalpies of formation of 1-nitrospiro[2.3]hexane, 7-nitrodispiro[3.0.3.1]nonane, and 1,1-dinitrocyclopropane were determined experimentally.     

Leggett-Williams norm-type theorems for coincidences

We study the existence of positive solutions to the operator equation Lx = Nx, where L is a linear Fredholm mapping of index zero and N is a nonlinear operator. Using the properties of cones in Banach spaces and Leray-Schauder degree for completely continuous operators, k-set contractions and condensing mappings, we obtain some refinements of the results established in [3] and [14]. Received: 9 July 2005; revised: 12 January 2006     

On Intersection Problem for Perfect Binary Codes

The main result is that to any even integer q in the interval 0 ≤ q ≤ 2^{n+1-2log(n+1)}, there are two perfect codes C₁ and C₂ of length n = 2^m − 1, m ≥ 4, such that |C₁ ∩ C₂| = q.     

Positive Steady States of a Prey-predator Model with Diffusion and Non-monotone Conversion Rate

In this paper, we study the positive steady states of a prey-predator model with diffusion throughout and a non-monotone conversion rate under the homogeneous Dirichlet boundary condition. We obtain some results of the existence and non-existence of positive steady states. The stability and uniqueness of positive steady states are also discussed.