Supporting visually impaired children with software agents in a multimodal learning environment

Visually impaired children have a great disadvantage in the modern society since their ability to use modern computer technology is limited due to inappropriate user interfaces. The aim of the work presented in this paper was to develop a multimodal software architecture and applications to support learning of visually impaired children. The software architecture is based on software agents, and has specific support for visual, auditory and haptic interaction. It has been used successfully with different groups of 7-8 year-old and 12 year-old visually impaired children. In this paper we discuss the enabling software technology and interaction techniques aimed to realize our goal and our experiences in the actual use of the system.     

Minimizing Wavelength Conversions in WDM Path Establishment*

This paper studies algorithms for connection establishment in wavelength division multiplexing networks. Although wavelength conversion capabilities are assumed at each node in the network, the goal of this research is to minimize or impose an upper bound on the number of wavelength conversions on the established path. Two types of schemes are investigated and compared. In the first scheme, the wavelengths are selected adaptively during path establishment on a given route, and in the second scheme, both the route and the wavelength assignment are selected optimally based on global information about path costs and wavelength availability in the network. We present two efficient algorithms for globally selecting routes and wavelengths, one finds the least cost route for a maximum number of wavelength conversions, and the other selects from among the shortest routes, the one with a minimum number of wavelength conversions. The results of comparing the two path establishment schemes show that, for dynamically changing traffic, the adaptive selection of wavelengths on a fixed route during path establishment is more beneficial than the optimal selection of the route and wavelengths prior to path establishment.     

Acoustic investigations on PbO-Al2O3-B2O3 glasses doped with certain rare earth ions

Elastic moduli (Y, η), Poisson’s ratio (σ), microhardness (H) and some thermodynamical parameters such as Debye temperature (θ_D), diffusion constant (D _i),latent heat of melting (ΔH _m) etc of PbO-Al₂O₃-B₂O₃ glasses doped with rare earth ions viz. Pr³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺ and Yb³⁺, are studied as functions of temperatures (in the temperature range 30–200°C) by ultrasonic techniques. All these parameters are found to increase with increasing atomic numberZ of the rare earth ions and found to decrease with increasing temperature of measurement. From these results (together with IR spectra of these glasses), an attempt is made to throw some light on the mechanical strength of these glasses.     

Investigation of compatible anode systems for LaNbO4-based electrolyte in novel proton conducting solid oxide fuel cells

In the current manufacturing process of novel LaNbO₄-based proton conducting fuel cells a thin layer of the electrolyte is deposited by wet ceramic coating on NiO-LaNbO₄ based anode and co-sintered at 1200-1300 °C. The chemical compatibility of NiO with acceptor doped LaNbO₄ material is crucial to ensure viability of the cell, so potential effects of other phases resulting from off-stoichiometry in acceptor doped LaNbO₄ should also be explored. Compatibility of NiO with Ca-doped LaNbO₄ and its typical off-set compositions (La₃NbO₇ and LaNb₃O₉) are investigated in this work. It is shown that while NiO does not react with Ca-doped LaNbO₄, fast reaction occurs with La₃NbO₇ or LaNb₃O₉. La₃NbO₇ and NiO form a mixed conducting perovskite phase LaNi_2/3Nb_1/3O₃, while LaNb₃O₉ and NiO form either NiNb₂O₆ or Ni₄Nb₂O₉ depending on the annealing temperature. This implies that manufacturing LaNbO₄-based proton conducting fuel cells requires a strict control of the stoichiometry of the electrolyte.     

Static output‐feedback for Takagi–Sugeno systems with delays

A practical methodology to design controllers for Takagi–Sugeno discrete‐time systems with unknown delays is proposed, based on using Linear Matrix Inequalities. More precisely, the design of discrete‐time output‐feedback stabilizing controllers in the presence of bounded delays is solved, when values of the disturbance attenuation and decay‐rate are imposed. A numerical example is provided to illustrate the proposed approach. Copyright © 2010 John Wiley & Sons, Ltd.     

Performance evaluation of multiuser diversity in multiuser two‐hop cooperative multi‐relay wireless networks using maximal ratio combining over Rayleigh fading channels

Multiuser diversity (MUD) cooperative wireless networks combine the features of the MIMO systems without confronting the physical layer constraints by providing multiple copies of the transmitted signal from the source to the destination with the help of the relay node. Cooperative wireless networks have attracted the full attention in the last few years and are implemented widely in many wireless communication systems to adapt for the fading impairments, provide higher data rates, and improve the performance of the wireless communication systems. In this paper, we present an informative study for the reason of evaluating the performance of the MUD in the multiuser two‐hop cooperative multi‐relay networks using maximal ratio combining. Furthermore, we derive tight closed‐form expressions of outage probability and symbol error probability for the amplify‐and‐forward and fixed decode‐and‐forward protocols with the MUD. Additionally, we conduct a simulation study to show to what extent our analytical and simulation results agree with each other. It is worthy to mention that our analytical and simulation results agree fairly with each other under high average signal‐to‐noise ratio, whereas they show that our proposed system with multiple relays provides significant improvements over those previously proposed systems having only one relay. Copyright © 2013 John Wiley & Sons, Ltd.     

Occurrence of the tdh and trh genes in Vibrio parahaemolyticus isolates from waters and raw shellfish collected in two French coastal areas and from seafood imported into France

The occurrence of the hemolysin genes, tdh and trh, in Vibrio parahaemolyticus strains isolated from environmental samples collected in two French coastal areas, clinical samples, and seafood products imported into France was studied. Polymerase chain reaction (PCR) with two sets of primers was used to detect the hemolysin genes. Most of the clinical isolates (91%) and 1.5% of the isolates from seafood possessed the hemolysin genes. Three and fifteen percent, respectively, of the two groups of environmental strains carried the hemolysin genes depending on the geographic site. The tdh and trh genes play important roles in virulence. Thus, our results indicate that pathogenic V. parahaemolyticus isolates are present in French coastal areas and in seafood imported into France. Furthermore, they may also be present in French seafood products.     

Interferometric measurement of laser heating in praseodymium-doped YAG crystal

Temperature measurement is required for many applications but can be difficult in some cases. Laser heating or cooling studies demand accurate measurements of temperature changes. A Michelson interferometer configuration has been used to investigate laser heating in solids. An analytical formula was derived to estimate the temperature change from the fringe count by taking into account the temperature dependence of the sample length and refractive index. When 115?mW of a focused Ar+ laser beam (488?nm) passes through a Pr(3+)-doped YAG sample, its temperature increased by 11.7±1.0?K along the beam path due to nonradiative relaxation. The power dependence of the fringe count/movement was recorded. The temperature change was estimated by the interferometric method and is in agreement with that measured by a thermocouple.