A performance evaluation of three multiagent platforms

In the last few years, many researchers have focused on testing the performance of Multiagent Platforms. Results obtained show a lack of performance and scalability on current Multiagent Platforms, but the existing research does not tackle poor efficiency causes. This article is aimed not only at testing the performance of Multiagent Platforms but also the discovery of Multiagent Platform design decisions that can lead to these deficiencies. Therefore, we are able to understand to what extent the internal design of a Multiagent Platform affects its performance. The experiments performed are focused on the features involved in agent communication.     

A design-oriented method to build correct hypermedia documents

Over the years, different approaches to identify temporal and spatial conflicts in hypermedia applications has been proposed. Most of them are based on formal verification techniques and impose to the designers to follow a formal model or language to ensure application’s functional correctness. Furthermore, the error diagnose is hard to be interpreted by a non-specialist in this domain. In this paper, we present an approach which supports formal verification for documents written in markup languages. We proposed a method and built a verification toolchain that helps designers to verify time and spatial constraints in hypermedia applications. The input language is the designer language. Its translation towards the input of toolchain is automatic and transparent for the application designer. The errors scenarios provided by the verification tool are presented in a timeline way, easily understandable by the designer. The method and toolchain support different markup languages translated in the same intermediary language in order to facilitate the use of different verification tools in the same environment.

     

Dispersion and reaction sintering of alumina–titania mixtures

Alumina–aluminium titanate (A–AT) composites are typically produced either by mixing the alumina matrix powder with already formed aluminium titanate or by reaction sintering of alumina and titania powders. Reaction-sintered materials usually exhibit limited final density and extensive microcracking. This paper describes the preparation of A–AT nanocomposites by slip casting and reaction sintering, using aqueous suspensions of submicrometre-sized alumina and nanometre-sized titania at a respective weight ratio of 87:13, which is typical for plasma-sprayed coatings. The colloidal stability of aqueous suspensions of the two individual powders and of their respective mixtures was determined first, measuring zeta potential and rheological behaviour as a function of deflocculant content and sonication time. The bimodal distribution yielded green relative densities of up to 70% of theoretical density. Dynamic and static sintering studies showed that aluminium titanate had already formed at 1400 °C.     

Triterpene alcohols, 4-methylsterols and 4-desmethylsterols of sal and illipe butters

Four 4-desmethylsterols, four 4-methylsterols and eight triterpene alcohols were isolated from sal and illipe butters and identified by¹H nuclear magnetic resonance and mass spectrometry. In addition to some components which had been shown to be present in these fats, several triterpene alcohols and one 4-methylsterol are described for the first time in these fats. An analytical method for detection of sal or illipe butters in foodstuffs is suggested.     

Diffusion of General Data on Non-Flat Manifolds via Harmonic Maps Theory: The Direction Diffusion Case

In a number of disciplines, directional data provides a fundamental source of information. A novel framework for isotropic and anisotropic diffusion of directions is presented in this paper. The framework can be applied both to denoise directional data and to obtain multiscale representations of it. The basic idea is to apply and extend results from the theory of harmonic maps, and in particular, harmonic maps in liquid crystals. This theory deals with the regularization of vectorial data, while satisfying the intrinsic unit norm constraint of directional data. We show the corresponding variational and partial differential equations formulations for isotropic diffusion, obtained from an L₂ norm, and edge preserving diffusion, obtained from an L norm in general and an L₁ norm in particular. In contrast with previous approaches, the framework is valid for directions in any dimensions, supports non-smooth data, and gives both isotropic and anisotropic formulations. In addition, the framework of harmonic maps here described can be used to diffuse and analyze general image data defined on general non-flat manifolds, that is, functions between two general manifolds. We present a number of theoretical results, open questions, and examples for gradient vectors, optical flow, and color images.     

Science, politics and image in Valencia: a review of urban discourse in the Spanish City

In the urban sphere, discourse is fundamental to the social and political construction of urban reality. The urban landscape is, in part, a result of those discourses. It is, as Richard Schein suggests, a discourse materialized. The production of these discourses throughout urban history both represented and constructed urban reality at any given time. For much of history, the written word was central to such discursive representations, literary formulations and even biological metaphors that sought to interpret the city both for local inhabitants and outsiders. Today, the photographic image has usurped the former dominance of the word. This article uses archival research to trace historical representations of Valencia, Spain, a European Mediterranean city with a strong medieval tradition. Beginning with a focus on the Fourteenth and Fifteenth Century, when Valencia was economic ‘head’ of the Kingdom of Aragon, this paper will follow how the city developed in concert with evolving intellectual and political representations of it. In doing so, I highlight the important and enduring role of the organic metaphor as a device which framed intellectual and political discourse, and ultimately planning and governing strategies, into urbanism of the Nineteenth and Twentieth Centuries (as reflected in the writings of Patrick Geddes). Throughout Valencia’s history, urban discourse has availed itself of biological and medical metaphors, even metaphors drawn from the field of physics, in order to construct a generally agreed-upon image of the urban society at particular historical moment. Analysing the role of such metaphors in urban discourse is fundamental to any full understanding of development in the Mediterranean city, historical or contemporary.     

Biological nitrogen removal of high-strength ammonium industrial wastewater with two-sludge system

The biological nitrogen removal (BNR) process is the most common method for removing low quantities of ammonium from wastewater, but this is not the usual treatment for high-strength ammonium wastewater. The capacity to biologically remove the nitrogen content of a real industrial wastewater with a concentration of 5000 g N-NH(4)(+) L(-1) is demonstrated in this work. The experimental system used is based on a two-sludge system, with a nitrifying activated sludge and a denitrifying activated sludge. This system treated real industrial wastewater for 450 days, and during this period, it showed the capacity for oxidizing all the ammonium at average nitrification rates between 0.11 and 0.18 g N-NH(4)(+)g VSS(-1)d(-1). Two key process parameters were evaluated: the maximum nitrification rate (MNR) and the maximum denitrification rate (MDR). MNR was determined in continuous operation at three different temperatures: 15 degrees C, 20 degrees C and 25 degrees C, obtaining values of 0.10, 0.21 and 0.37 g N-NH(4)(+) g VSS(-1)d(-1), respectively. Complete denitrification was achieved using two different industrial carbon sources, one containing mainly ethanol and the other one methanol. The MDR reached with ethanol (0.64 g N-NO(x)(-) g VSS(-1)d(-1)) was about 6 times higher than the MDR reached with methanol (0.11g N-NO(x)(-)g VSS(-1)d(-1)).