On the use of genuine-impostor statistical information for score fusion in multimodal biometrics/sur l’usage de l’information statistioue client-imposteur pour la fusion des scores en biométrie multimodale

Matching score level fusion techniques in multimodal person verification conventionally use global score statistics in the normalization and fusion stages. In this paper, novel normalization and fusion methods are presented to take advantage of the separate statistics of the monomodal scores in order to reduce the genuine and impostor pdf lobe overlapping and improve the verification rate. Joint mean normalization is an affine transformation that normalizes the mean of the monomodal biometrics scores separately for the genuine and impostor individuals. Histogram equalization is used to align the statistical distribution of the monomodal scores and make the whole separate statistics comparable. The presented weighting fusion methods have been designed to minimize the variances of the separate multimodal statistics and reduce the multimodal pdf lobe overlapping. The results obtained in speech and face scores fusion upon polycost and xm2vts databases show that the proposed techniques provide better results than the conventional methods.     

Materials development for intermediate-temperature solid oxide electrochemical devices

One of the major challenges in developing electrochemical devices for energy generation has been the identification and development of materials with outstanding performance at reduced (intermediate) temperatures (500–700 °C), increasing the durability and lowering the cost of the device. A solid-state electrochemical cell is in outline a simple device consisting of three components: anode, electrolyte and cathode. The function of each component is critical to cell performance, and as interest in fuel cells and electrolysers has gathered pace, many materials have been evaluated as functional components of these cells. Typically, the requirement for new materials development has been the drive to lower operation temperature, overcoming sluggish reaction kinetics in existing materials. Novel materials for the functional components of both electrolysers and fuel cells are introduced, with emphasis placed on the air electrode and electrolyte, with the potential of new classes of materials discussed, including layered materials, defect fluorites and tetrahedrally coordinated phases. Furthermore, the opportunity presented by thin film deposition to characterize anisotropic transport in materials and develop devices based on thin films is discussed.     

Polyethylene terephthalate/low density polyethylene/titanium dioxide blend nanocomposites: Morphology,crystallinity, rheology,and transport properties

Physical features of polyethylene terephthalate (PET)/low density polyethylene (LDPE) immiscible blends, rich in PET, with and without titanium dioxide (TiO₂) nanoparticles are studied. These materials are of industrial interest, because they can be obtained by recycling PET bottles containing TiO₂ with their corresponding polyethylene made caps. Their potential application in packaging is investigated. Droplet-matrix morphology is observed by scanning electron microscopy; coalescence occurs during compression molding. Transmission electron microscopy results show that TiO₂ nanoparticles are located at the interface between PET and LDPE, forming a physical barrier that favors development of smaller droplets. Thermal analysis results are compatible with the morphology of the blends and the location of the TiO₂ nanoparticles. Viscosity obtained by extrusion continuous flow and oscillatory flow measurements in the linear regime show that some of the blends have viscoplastic behavior. Permeability results reveal that 80PET/20LDPE/TiO₂ blend nanocomposite shows a balanced barrier character to both oxygen and water vapor. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46986.     

A 0.6 V and 0.395 pJ/bit nonius TDC for a passive RFID pressure sensor tag

This work presents a nonius time to digital converter (TDC) adapted to a passive RF identification (RFID) pressure sensor tag. The proposed converter exploits the characteristics of time-based sensor interfaces and allows reducing voltage supply and power consumption while maintaining resolution and conversion efficiency. The nonius TDC has been designed and fabricated using the TSMC 90 nm standard CMOS technology. The main blocks of the converter are described and both the resolution adjustment and measurement processes are explained in detail. Measurement results show 10.49 bits of effective resolution for an input time range from 28.19 to 42.93 μs. With a sampling rate of 19 KS/s the converter has a conversion efficiency of 0.395 pJ/bit with a voltage supply of only 0.6 V. This characteristics in the proposed nonius TDC enables an increased reading range of the passive RFID pressure sensor tag.     

Effect of H12MDI isomer composition on mechanical and physico-chemical properties of polyurethanes based on amorphous and semicrystalline soft segments

Two series of segmented thermoplastic polyurethanes were synthesized having 33 wt % hard segment based on 4,4′-dicyclohexyl methane diisocyanate with different trans–trans isomer contents and 1,3-propanediol chain extender. The soft segments were based on poly(hexamethylene–pentamethylene carbonate)diol and poly(butylene sebacate)diol, amorphous and semicrystalline polyol, respectively. 4,4′-Dicyclohexyl methane diisocyanate with different trans–trans isomer contents were obtained by fractional crystallization of commercial diisocyanate and were characterized by differential scanning calorimetry and nuclear magnetic resonance spectroscopy. 4,4′-Dicyclohexyl methane diisocyanate trans–trans isomer lead to some interesting properties in the synthesized polyurethanes, due to the more ordered hard domains formed by packing of trans–trans 4,4′-dicyclohexyl methane diisocyanate. Thereby, as 4,4′-dicyclohexyl methane diisocyanate trans–trans isomer content increased, a better phase separated structure was observed.     

The Formation of Performance Enhancing Pseudo‐Composites in the Highly Active La1–xCaxFe0.8Ni0.2O3 System for IT‐SOFC Application

The La_1–xCa_xFe_0.8Ni_0.2O_3–δ (0 ≤ x ≤ 0.9) system is investigated for potential application as a cathode material for intermediate temperature solid oxide fuel cells (IT‐SOFCs). A broad range of experimental techniques have been utilized in order to elucidate the characteristics of the entire compositional range. Low A‐site Ca content compositions (x ≤ 0.4) feature a single perovskite solid solution. Compositions with 40% Ca content (x = 0.4) exhibit the highest electrical and ionic conductivities of these single phase materials (250 and 1.9 × 10^?3 S cm^?1 at 800 °C, respectively), a level competitive with state‐of‐the‐art (La,Sr)(Fe,Co)O₃. Between 40 and 50% Ca content (0.4 > x > 0.5) a solubility limit is reached and a secondary, brownmillerite‐type phase appears for all higher Ca content compositions (0.5 ≤ x ≤ 0.9). While typically seen as detrimental to electrochemical performance in cathode materials, this phase brings with it ionic conductivity at operational temperatures. This gives rise to the effective formation of pseudo‐composite materials which feature significantly enhanced performance characteristics, while also providing the closest match in thermal expansion behavior to typical electrolyte materials. This all comes with the advantage of being produced through a simple, single‐step, low‐cost production route without the issues associated with typical composite materials. The highest performing pseudo‐composite material (x = 0.5) exhibits electronic conductivity of 300–350 S cm^?1 in the 600–800 °C temperature range while the best polarisation resistance (R_p) values of approximately 0.2 Ω cm² are found in the 0.5 ≤ x ≤ 0.7 range.     

Improving the barrier character of poly(caprolactone): Transport properties and free volume of immiscible blends

In this work, the barrier character of poly(caprolactone) is improved with the addition of a poly(hydroxy amino ether). The analysis by means of thermal, thermomechanical, and morphology characterization reveals that the blends are partially miscible. The characterization of the morphology has revealed that the blends show a droplet matrix morphology. The free volume of the samples has been characterized by positron annihilation lifetime spectroscopy observing a decrease in the free volume as the poly(hydroxyamino ether) (PHAE) content increases. The barrier character to water vapor and carbon dioxide is greatly improved with the addition of PHAE. However, the observed improvement does not arise only from the reduced free volume, playing the interactions between penetrants and polymers a major role. Overall, this work aims to provide a further insight on the factors affecting the improvement of the barrier character of biodegradable polymers, which would allow developing new materials for packaging applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48018.