Abstract
The development of an intelligent wheel chair (IW) platform that may be easily adapted to any commercial electric powered wheelchair and aid any person with special mobility needs is the main objective of the IntellWheels project. To be able to achieve this main objective, three distinct control methods were implemented in the IW: manual, shared and automatic. Several algorithms were developed for each of these control methods. This paper presents three of the most significant of those algorithms with emphasis on the shared control method. Experiments were performed by users suffering from cerebral palsy, using a realistic simulator, in order to validate the approach. The experiments revealed the importance of using shared (aided) controls for users with severe disabilities. The patients still felt having complete control over the wheelchair movement when using a shared control at a 50 % level and thus this control type was very well accepted. Thus it may be used in intelligent wheelchairs since it is able to correct the direction in case of involuntary movements of the user but still gives him a sense of complete control over the IW movement.

Abstract
Educational Modelling Languages (EML) are conceptual and technical tools that allow enhancing e-learning through the representation of educational processes and their transformation into operable products to Learning Management Systems (LMS). Through visual notations it's possible to do reviews and adjustments of represented learning objects (LO). IMS-Learning Design (IMS-LD) is a LO specification language. One of its major strengths is the interoperability of specification products. Its use by non-technical users isn't a simple task, and limitations are pointed out. Intermediate software have been developed to facilitate the specification, authoring tools called graphic editors as Reload LD Editor, GLM, Collage and CADMOS, among others. Graphic editors can be used as educational planning tools in the context of e-learning. Planning a LO is drawing a structure of tasks, describing all aspects that frame the learning activities that can be generated to achieve the outlined goals (e.g. participants, tasks, resources, targets and risks to be considered). Despite being a complex activity, it's essential for teachers. In this work we focused on CADMOS, because it's devoted to create specifications for Moodle, one of the most used LMS by teachers. The main goal is study CADMOS, trying to identify its potentialities and limitations as planning tool capable of represent all aspects of a LO. Therefore the research questions are: Is it possible specify all aspects that characterize the LO using CADMOS? Do the limitations in specification influence the automatic operationalization of the LO in LMS? Tests done with CADMOS were divided in two parts: 1) Specification of a LO, consisting of a task module on a specific theme, that took place in LMS Moodle of a Portuguese higher education institution, as part of a course in a program of Computer Engineering. 2) Specification result has been converted into an interoperable data packet, which was imported to the LMS. After the automatic creation of the LO were analysed the similarities with the original LO. Results showed that there were differences between the two LO. A primitive structure of LO is created in LMS, but extra work performed by the teacher is required to complete the configuration of the activities. Additional points were found: a) When specifying there isn't the possibility to configure all required aspects of a Moodle activity (e.g. wiki). Teacher has to do it manually directly in the LMS. b) Limitations in the automation process of operationalization of the LO in LMS, related to the specification process were found. Is necessary consider the representation structure adopted in LO specification with CADMOS. It offers different functions to do it, which are used or not depending on the way user conceives the LO. This leads to different representations in LMS. As planning tool CADMOS can be useful and has advantages, as the possibility of having different views of the process (conceptual model/ flow model), and chance to save, change, reuse and share several times a specification product. Its major weakness is in automatic creation of the LO in LMS. Thus, we believe that CADMOS and other graphic editors are likely to be important planning tools for teachers. However, more tests with different LO and improvements are needed to achieve faithful automating creation of LO in LMS, allowing teachers to be focused on central aspects of teaching.

Abstract
This paper analyses the relationship among marginal costs per power plant, fossil fuel prices and electricity bidding quantities in the Spanish electricity market. The results of the panel cointegration and Granger causality methods clearly indicate a differential impact of fossil fuel prices on power plants marginal costs, with a positive effect for gas power plants. The biggest negative impact on marginal costs is seen for coal technology. As a consequence of the characteristics of different production technologies, the set of marginal costs across the sample is based on coal power plants, although Endesa and Iberdrola's marginal costs are predominantly based on gas power plants. Operating costs for hydroelectric power plants are very low when compared to the thermal power plants, which is the base technology used by Endesa, since this technology is strongly dependent on the volatility of commodity markets and on the supply chain and production costs management. Copyright © 2015 Inderscience Enterprises Ltd.

Abstract

Abstract

Abstract
In this paper, we present the numerical and the experimental results of a new low cost surface plasmon resonance sensor configuration. It is based on a plasmonic sensor platform and an efficient higher order modes filtering in plastic multimode fibers, exploiting a tapered plastic optical fiber at the output of the sensor system. The experimental results have demonstrated that the tapered filter positioned after the sensor system improves the performances in terms of refractive index range and depth of the resonance curve. The results are in agreement with the numerical simulations.