Web-based systems design: a study of contemporary practices and an explanatory framework based on “method-in-action”

This paper reports the findings of a detailed study of Web-based systems design (WBSD) practices in Ireland based on data collected over a 3-year period (2002–2005), the objectives of which were to (1) contribute towards a richer understanding of the current “real-world” context of WBSD by characterising the profile of a typical project (team size, timeframe, nature of requirements, etc.) and identifying the key challenges, constraints, and imperatives (i.e. “mediating factors”) faced by Web-based system designers, and (2) understand how those contextual parameters and mediating factors influence the activity of WBSD as regards the selection and enactment of whatever design practices are therefore engaged (i.e. the use of methods, procedures, etc.). Data was gathered through a survey which yielded 165 usable responses, and later through a series of semi-structured qualitative interviews. Using grounded theory, an explanatory conceptual framework is derived, based on an extension of the “method-in-action” model, the application of which to WBSD has not been previously investigated in depth. It is proposed that this framework of WBSD issues is valuable in a number of ways to educators, researchers, practitioners, and method engineers.     

Rheology in Processing of in Situ Composites of Polypropylene and Low Melting Poing Metals

The low melting point metallic tin powder or alloy of tin and lead was blended with polypropy-lene. A kind of in situ composite has been prepared. The variations of torque were studied when the composites were mixed in Haake torque rheogeniometer. By way of capillary extrusion, effects upon rheology of the in situ com-posites of the low melting point metals (LMPM) and coupling agent for their different variety and content, were investigated. From flow curves, the results indicate that in situ composites mixed with the LMPM are a kind of pseudoplastic fluid. If the LMPM were melted, the higher the content of the LMPM , the lower apparent viscosity of composites. Meanwhile, when the coupling agent is added into composites, the viscosity of composite will go up first and drop then. This shows that the LMPM have a promoter flow action on the polypropylene.     

Equivalent Conditions for Convergence of Splittings of Non-Hermitian Indefinite Matrices

We present some sufficient and necessary conditions for convergent splitting of a non-Hermitian indefinite matrix. Some sufficient conditions to determinate a matrix with a (strongly) dominant symmetric part for a class of boundary value problem are also obtained. These results are applicable to identify the convergence of iterative methods for solving large sparse systems of linear equations.     

Oxidation of Fe (II) in sulfuric acid solutions with dissolved molecular oxygen

The oxidation of Fe(II) with dissolved molecular oxygen was studied in sulfuric acid solutions containing 0.2 mol . dm^-3 FeSO₄ at temperatures ranging from 343 to 363 K. In solutions of sulfuric acid above 0.4 mol . dm^-3, the oxidation of Fe (II) was found to proceed through two parallel paths. In one path the reaction rate was proportional to both [Fe²⁺]² and po₂, exhibiting an activation energy of 51.6 . kJ mol^-1. In another path the reaction rate was proportional to [Fe²⁺]², [SO_4-], and po₂ with an activation energy of 144.6 kJ . mol^-1. A reaction mechanism in which the SO_4- ions play an important role was proposed for the oxidation of Fe(II). In dilute solutions of sulfuric acid below 0.4 mol . dm^-3, the rate of the oxidation reaction was found to be proportional to both [Fe(II)]² and Po₂, and was also affected by [H⁺] and [SO_2- ⁴]. The decrease in [H⁺] resulted in the increase of reaction rate. The discussion was further extended to the effect of Fe (III) on the oxidation reaction of Fe (II).     

The prospects of non-volatile phase-change RAM

Phase-change read-and-write memory (PRAM) is a promising memory that can solve the problems of conventional memory—scalability, read/write speed, and reliability. We will review the opportunities and technical challenges of PRAM. The most important challenge of PRAM is the reduction of the writing current. Various approaches to reduce the writing current will be reviewed and the prospects of PRAM are discussed.