Simulation of complex environments:the Fuzzy Cognitive Agent

The world is becoming increasingly competitive by the action of liberalised national and global markets. In parallel these markets have become increasingly complex making it difficult for participants to optimise their trading actions. In response, many differing computer simulation techniques have been investigated to develop either a deeper understanding of these evolving markets or to create effective system support tools. In this paper we report our efforts to develop a novel simulation platform using fuzzy cognitive agents (FCA). Our approach encapsulates fuzzy cognitive maps (FCM) generated on the Matlab Simulink platform within commercially available agent software. We firstly present our implementation of Matlab Simulink FCMs and then show how such FCMs can be integrated within a conceptual FCA architecture. Finally we report on our efforts to realise an FCA by the integration of a Matlab Simulink based FCM with the Jack Intelligent Agent Toolkit

Hyperelastic modelling of nonlinear running surfaces

Accurate, 3-D analyses of running impact require a constitutive model of the running surface that includes the material nonlinearity shown by many modern surfaces. This paper describes a hyperelastic continuum that mimics the experimentally measured response of a particular treadmill surface. The material model sacrifices a little accuracy to admit a robust, low-order hyperelastic strain-energy functional. This helps prevent the premature termination of finite element simulations, due to numerical or material instabilities, that can occur with higher-order functionals. With only two free constants, it is also a more practical design tool. The best fit to the quasi-static response of the treadmill was achieved with an initial shear modulus =2 MPa and a power-stiffening index =25. The paper outlines the method used to derive the material constants for the treadmill, a device that is not amenable to the usual materials laboratory tests and must be reverse-engineered. Finite element analyses were then performed to ensure that the treadmill model interacts with the other components of the multibody running system in a numerically stable and physically realistic manner. The model surface was struck by a rigid heel, cushioned by a hyperfoam material that represents a shoe midsole. The results show that, while the ground reaction force is similar to that obtained with a rigid surface, the maximum principal stress in the shoe is reduced by 15%. Such a reduction, particularly when endured over many load cycles, may have a significant effect on comfort and damage to nearby tissue

A low-power circuit for piezoelectric vibration control by synchronized switching on voltage sources

In the paper, a vibration damping system powered by harvested energy with implementation of the so-called SSDV (synchronized switch damping on voltage source) technique is designed and investigated. In the semi-passive approach, the piezoelectric element is intermittently switched from open-circuit to specific impedance synchronously with the structural vibration. Due to this switching procedure, a phase difference appears between the strain induced by vibration and the resulting voltage, thus creating energy dissipation. By supplying the energy collected from the piezoelectric materials to the switching circuit, a new low-power device using the SSDV technique is proposed. Compared with the original self-powered SSDI (synchronized switch damping on inductor), such a device can significantly improve its performance of vibration control. Its effectiveness in the single-mode resonant damping of a composite beam is validated by the experimental results.Comment: 11 page

Class B greenhouse model with double layer for Nordic European countries

[EN] This paper presents functional and structural possibilities of Class B greenhouses, which has a film covered, for areas with extreme winter temperatures and heavy snow loads, which are typical of a Class A model (glass or rigid film covered). This greenhouse study covers from its analysis in the design phase to its correct operation after construction, breaking patterns set by European standard, due to the structural design of the greenhouse, providing new possibilities for this type B, restricted to a specific geographical area so far.We gratefully acknowledge INVERCA S.A for work and technical assistance, and provide data and information necessary after construction of the greenhouse.Rovira Soler, JA.; Martín Concepcion, PE.; Almerich Chulia, AI.; Molines Cano, JM. (2014). Class B greenhouse model with double layer for Nordic European countries. Advanced Materials Research. 1065-1069:1046-1051. doi:10.4028/www.scientific.net/AMR.1065-1069.1046S104610511065-1069K. Berna. Structural analysis of greenhouse: a case study in Turkey. Building and Environment Vol. 41 (2006), pp.864-871.J. Nebot, J. Rovira, J. Garro, J. Martin, A. Aguado, A. Bonilla, A. Alonso, A. Committee technical CEN nº 284 (1998).J. Bosco. Horticultura. Revista de Hortaliza, Flores y Plantas Ornamentales Vol. 6. (1992).EN13031-1. Greenhouse: Design and construction - Part 1: Commercial production greenhouses (2002).P. Martin. Invernaderos de cubierta flexible: modelización de la acción del viento. Thesis. Editorial UPV (2003).O. Yekutieli, L. Dubinski, I. Kleinmann. Analysis of forces acting due to strong wind loads on structure and cover of walk-in tunnel. International Conference and British-Israeli workshop on greenhouse technologies (1997), pp.53-61.A. Mistriotis, D. Briassoulis. Numerical estimation of the internal and external aerodynamic coefficients of a tunnel greenhouse structure with openings. Computers and Electronics in Agriculture Vol. 34 (2002), pp.191-205.D. Briassoulis. Mechanical design requirements for low tunnel biodegradable and conventional films. Biosystems Engineering Vol. 87 (2) (2004), pp.209-223.A. Robertson, P. Roux, J. Gratraud, G. Scarascia, S. Castellano, M. Dufresne de Virel, P. Palier. Wind pressures on permeably and impermeably-clad structures. Journal of Wind Engineering and Industrial Aerodynamics Vol. 90 (4-5) (2002)

Aided diagnosis of structural pathologies with an expert system

Sustainability and safety are social demands for long-life buildings. Suitable inspection and maintenance tasks on structural elements are needed for keeping buildings safely in service. Any malfunction that causes structural damage could be called pathology by analogy between structural engineering and medicine. Even the easiest evaluation tasks require expensive training periods that may be shortened with a suitable tool. This work presents an expert system (called Doctor House or DH) for diagnosing pathologies of structural elements in buildings. DH differs from other expert systems when it deals with uncertainty in a far easier but still useful way and it is capable of aiding during the initial survey 'in situ', when damage should be detected at a glance. DH is a powerful tool that represents complex knowledge gathered from bibliography and experts. Knowledge codification and uncertainty treatment are the main achievements presented. Finally, DH was tested and validated during real surveys.Peer ReviewedPostprint (author's final draft

Algorithm engineering for optimal alignment of protein structure distance matrices

Protein structural alignment is an important problem in computational biology. In this paper, we present first successes on provably optimal pairwise alignment of protein inter-residue distance matrices, using the popular Dali scoring function. We introduce the structural alignment problem formally, which enables us to express a variety of scoring functions used in previous work as special cases in a unified framework. Further, we propose the first mathematical model for computing optimal structural alignments based on dense inter-residue distance matrices. We therefore reformulate the problem as a special graph problem and give a tight integer linear programming model. We then present algorithm engineering techniques to handle the huge integer linear programs of real-life distance matrix alignment problems. Applying these techniques, we can compute provably optimal Dali alignments for the very first time

Software systems through complex networks science: Review, analysis and applications

Complex software systems are among most sophisticated human-made systems, yet only little is known about the actual structure of 'good' software. We here study different software systems developed in Java from the perspective of network science. The study reveals that network theory can provide a prominent set of techniques for the exploratory analysis of large complex software system. We further identify several applications in software engineering, and propose different network-based quality indicators that address software design, efficiency, reusability, vulnerability, controllability and other. We also highlight various interesting findings, e.g., software systems are highly vulnerable to processes like bug propagation, however, they are not easily controllable