Speaker identification for security systems usingreinforcement-trained pRAM neural network architectures

Speaker identification may be employed as part of a security system requiring user authentication. In this case, the claimed identity of the user is known from a magnetic card and PIN number, for example, and an utterance is requested to confirm the identity of the user. A fast response is necessary in the confirmation phase and a fast registration process for new users is desirable. The time encoded signal processing and recognition (TESPAR) digital language is used to preprocess the speech signal. A speaker cannot be identified directly from the single TESPAR vector since there is a highly nonlinear relationship between the vector's components such that vectors are not linearly separable. Therefore the vector and its characteristics suggest that classification using a neural network will provide an effective solution. Good classification performance has been achieved using a probabilistic RAM (pRAM) neuron. Four probabilistic pRAM neural network architectures are presented. A performance of approximately 97% correct classifications has been obtained, which is similar to results obtained elsewhere (M. Sharma and R.J. Mammone, 1996), and slightly better than a MLP network. No speech recognition stage was used in obtaining these results, so the performance relates only to identifying a speaker's voice and is therefore independent of the spoken phrase. This has been achieved in a hardware-realizable system which may be incorporated into a smart-card or similar application     

Residual grain-interaction stresses in zirconium alloys

Residual grain-interaction stresses develop during the thermomechanical treatment of Zr alloys due to the anisotropy of the mechanical and thermal properties of the hep lattice. The origin and characteristics of this type of residual stress are described in conjunction with underlying physical principles employed to measure grain-interaction strains by means of neutron diffraction. The effect of thermal treatments, deformation, and irradiation on the evolution of residual grain-interaction strains are reviewed, and the most up-to-date experimental results are presented. The effects of grain-interaction stresses on the plasticity and in-reactor deformation of ZIRCALOY-2 will be discussed. This paper is based on a presentation made in the symposium “Irradiation-Enhanced Materials Science and Engineering” presented as part of the ASM INTERNATIONAL 75th Anniversary celebration at the 1988 World Materials Congress in Chicago, IL, September 25–29, 1988, under the auspices of the Nuclear Materials Committee of TMS-AIME and ASM-MSD.     

Composition and Antioxidant Activity of Olive Leaf Extracts from Greek Olive Cultivars

The olive leaf phenolic composition of the Greek cultivars koroneiki, megaritiki and kalamon was determined using LC/MS. Furthermore, the antioxidant activity of olive leaf extracts from the above three cultivars, using solvents of increasing polarity (petroleum ether, dichloromethane, methanol and methanol/water: 60/40) was evaluated using the stable free radical diphenylpicrylhydrazyl (DPPH) test. Furthermore the oxidative stability index (OSI) was compared to that of the synthetic antioxidant TBHQ and commercial oleoresin (rosemary extract). The ability of phenolic compounds to inhibit the lipoxygenase (LOX) activity was also investigated. The ten main components determined in the olive tree leaf extracts for the cultivars koroneiki and kalamon were: secologanoside, dimethyloleuropein, oleuropein diglucoside, luteolin-7-O-glucoside, rutin, oleuropein, oleuroside, quercetin, ligstroside and verbascoside. Respective compounds for the cultivar megaritiki were: secologanoside, dimethyloleuropein, oleuropein diglucoside, luteolin7-O-glucoside, oleuropein, oleuroside, quercetin and ligstroside. In all three cultivars, oleuropein represented the main phenolic component. The solvent polarity influenced the total amount of the phenolic compounds determined. When methanol/water (60/40) was used, as solvent, more phenolic compounds were determined. The total amounts of phenols determined in the extracts, obtained by successive extractions using the above solvents, were 6,094, 5,579 and 6,196 mg/kg (mg gallic acid/kg dried olive leaves) for the cultivars megaritiki, kalamon and koroneiki, respectively. Among all extracts, methanol/water extracts exhibited the highest antioxidant activity as shown through the application of the DPPH and OSI methods. The OSI antioxidant activity followed the sequence: synthetic antioxidant TBHQ > commercial oleoresin > olive tree leaf extracts > control. Likewise, methanol/water olive leaf extracts significantly inhibited soybean lipoxygenase, although some small differences in the activity among the olive leaf extracts of the different cultivars were observed. The solvent polarity as well as the amount of the extract influenced the inhibitory activity. A positive correlation was shown between the antioxidant activity of leaf extracts and the total phenol content.     

Bonding behaviour of chemically modified wood particles for board production

The objective of this paper was to evaluate the bonding behaviour of chemically modified wood particles towards an isocyanate resin system, as determined from internal bond strength of the board, and to determine which resin system, isocyanate or formaldehyde is suitable for use in boards made from modified raw material. It was found that chemical modification of wood chips and strands did not significantly affect the bonding efficiency of isocyanate resin, but the bonding efficiency of formaldehyde resins was strongly influenced. This behaviour can be a consequence of the usage of a less pH dependent resin that is fully cured during hot pressing in combination with the high mobility of the resin which causes penetration to considerable depth into compressed particles repairing weak zones, which are created during the modification process as chips are exposed to elevated temperatures, by sticking them together. It is suggested therefore, that the isocyanate resin system is more suitable for use in boards made from modified raw material than the formaldehyde resin system.     

Ubiquitous Agents for Ambient Ecologies

The cost of state-of-the-art devices and robots is critical for the uptake of Ambient Intelligence (AmI). One way to utilize low-cost hardware for both devices and robots is to run smart software remotely as agents deployed on computationally rich environments. In this context, the devices and the robots can be seen as the Avatars of agents, while the way devices and agents are related may be considered as an Ambient Ecology. We show how the application of a middleware platform called EVATAR realizes this vision by exemplifying the main issues with a multi-robot and a smart-home scenarios.     

Experimental determination of the stability of retained austenite in low alloy TRIP steels

The stability of retained austenite is the most important parameter controlling the transformation plasticity effects in multiphase low alloy TRIP steels. In this work the thermodynamic stability of the retained austenite has been determined experimentally by measuring the M^σ_s temperature as a function of bainite isothermal transformation (BIT) temperature and time in two low alloy TRIP steels. A single-specimen temperature-variable tension test technique (SS-TV-TT) has been employed, which allowed to link the appearance of yield points in the stress-strain curve with the mechanically-induced martensitic transformation of the retained austenite. The results indicated that the M^σ_S temperature varies with BIT temperature and time. Higher austenite stability is associated with a BIT temperature of 400°C rather than 375°C. In addition, the chemical stabilization of the retained austenite associated with carbon enrichment from the growing bainite is lowered at short BIT times. This stability drop is due to carbide precipitation and comes earlier in the Nb-containing steel. At longer BIT times the retained austenite dispersion becomes finer and its stability rises due to size stabilization. The experimental results are in good agreement with model predictions within the range of anticipated carbon enrichment of the retained austenite and measured austenite particle size.     

A mathematical model to study the effect of the air jet in the film blowing process

The aerodynamic effect of the air jet that supports the polymeric films produced in the film blowing process is studied theoretically. The nonlinear coupling between the air and the polymer is examined by assuming steady, axisymmetric, and isothermal flow for both phases. The governing equations for the polymer are simplified by following the thin‐film approximation and the corresponding ones for the air are derived by applying a boundary‐layer type analysis. The latter are solved analytically by first applying the Mangler transformation that reduces the boundary layer equations for the axisymmetric case to those for a plane boundary layer. Then a similarity solution is obtained, allowing the shear stress and the pressure on the outer polymer/air interface to be evaluated in terms of the film shape only. The final set of ordinary differential equations for the film is solved numerically using finite differences. The results show that the force caused by the airflow has a significant effect on the film shape and the characteristics of the final product. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Planar Spatial Arrangement of Precipitates in 0.3C-30Ni 18Cr-0.9Ti Austenitic Cast Steel Aged at 600 °C for 10 h

A method to determine the basic parameters describing planar two-dimensional (2D) spatial arrangements of precipitates is presented. It is based on the observation that the total number of particles (precipitates), the total area, and total perimeter length of features examined in the microstructure at each step of dilation/erosion transformation uniquely depend on their initial 2D geometry (size, shape, and mutual spatial arrangements). These parameters have a clear physical interpretation such as the distribution of distances between precipitate boundaries that are measured along the shortest pathway between them. It is also argued that the network of the shortest pathway represents the dendrite and sub-grain boundaries. On this basis, the width distributions of the dendrites and sub-grains were determined.