A Sharp Interface Model of Intermediate-Phase Growth Under the Influence of Electromigration

A sharp interface model has been developed to model intermediate-phase growth under the influence of electromigration in a binary system. Simulation results show that the phase growth rate depends on both the magnitude and the direction of the applied current. With the current density fixed, at early times, there is a parabolic growth behavior for the intermediate phase, while at longer times, there is a linear phase growth behavior when the electron flow aids diffusion of atoms; however, a limiting thickness is found when the electron flow hinders diffusion. Qualitative analysis shows that the longer time behavior also holds in a binary system with multiple intermediate phases present.     

Studies on Conducting Polypyrrole/Graphene Oxide Composites as Supercapacitor Electrode

An electrode material based on polypyrrole (PPy) doped with graphene oxide (GO) sheets was synthesized via in situ polymerization of pyrrole in the presence of GO in various proportions (5% and 10%). The synthesized samples were characterized by Fourier-transform infrared (FTIR) spectroscopy, ultraviolet–visible (UV–vis) absorption spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), x-ray diffraction (XRD) analysis, and electrical conductivity measurements. FTIR spectroscopy and XRD revealed the interaction between GO and PPy. The direct-current (DC) electrical conductivity (75.8 S/cm) of the prepared composites was dramatically enhanced compared with pure PPy (1.18 S/cm). High specific capacitance of PPy/GO composite of 421.4 F/g was obtained in the potential range from 0 V to 0.50 V at 2 mA compared with 237.2 F/g for pure PPy by galvanostatic charge–discharge analysis. Incorporation of GO into the PPy matrix has a pronounced effect on the electrical conductivity and electrochemical capacitance performance of PPy/GO nanocomposites.     

Microstructure and Thermoelectric Properties of Dense YB<Subscript>22</Subscript>C<Subscript>2</Subscript>N Samples Fabricated Through Spark Plasma Sintering

Dense samples of the higher boride YB₂₂C₂N have been fabricated through the spark plasma sintering (SPS) method with different sintering aids. YB₂₂C₂N is a representative of a series of newly discovered rare-earth borocarbonitrides, which may be the long-awaited n-type counterpart of boron carbide, “B₄C.” The effect of Si, SiC, Al, and TiC additions on the sintering process of YB₂₂C₂N has been studied. The best sintered bodies with densities higher than 90% of theoretical density were obtained by means of SPS at 1700°C. We show that the additive choice and pressure have an effect on grain size and density. An investigation of the effect of atmosphere on the sintering behavior has also been carried out. It was found that sinterability is enhanced under nitrogen atmosphere. Thermoelectric properties of the materials sintered with additives have been evaluated, and we discuss their dependences on the fabrication process route.     

Aqueous-Develop,Photosensitive Polynorbornene Dielectric: Optimization of Mechanical and Electrical Properties

The impact of thermal cure conditions on the mechanical and electrical properties of an epoxy cross-linked network incorporating a polynorbornene (PNB) dielectric polymer was studied. The cross-linking of the dielectric composition was achieved by an acid-catalyzed cationic cure reaction initiated by either thermal or photolytic activation of a photoacid generator. It is proposed that the observed mechanical and electrical properties of the fully cured polymer composition are the result of the development of a three-dimensional cross-linked network tying together the PNB polymer and multifunctional epoxy additives. The epoxy ring-opening reaction was measured using Fourier-transform infrared spectroscopy. The reduced modulus, internal film stress, dielectric constant, and swelling behavior of cross-linked films were studied as a function of curing temperature. Trends in the observed properties are explained by formation of a three-dimensional cross-linked network and degradation of the cross-links between the multifunctional epoxy additives at high temperature. It was also found that exposure of the film to aqueous base plays a role in the cure process and has a positive effect on the final properties. The optimum values of modulus, dielectric constant, residual stress, and moisture content were found for films cured at 160°C for 1 h. This relatively low cure temperature is potentially advantageous in device assembly and processing.     

A Java Framework to Specify Faultloads for Fault Injection Campaigns

In an operational environment, the identification and reproduction of faults may be hard to be done, specially in complex systems. Use of fault injection accelerates this process, improving the test of fault tolerance mechanisms. However, there are a significant amount of fault injectors available, using several different approaches. This diversity of tools, each one with different methods to describe faultloads for fault injection campaigns, imposes severe obstacles to the efficient use of such fault injectors. In this context, this paper presents jFaultload, which applies Java for the specification of faultloads and translates them to specific formats that are appropriate to each available fault injector. Fault injectors for communication systems were integrated in the environment and completes the test scenario. The service under test used to demonstrate the usability and expressiveness of our solution is a video streaming session using RTP Protocol.     

The gray level aura matrices for textured image segmentation

Inspired by an intuitive analogy that exists between the gray level textures and the miscibility in the multiphase fluids, the aura concept was developed from set theory tools in order to modeling the texture image. The gray level aura matrix (GLAM) has been then proposed to generalize the gray level cooccurrence matrix (GLCM) which remains very popular in the texture analysis. The GLAM indicates how much each gray level is present in the neighborhood of each other gray level. The neighborhood is defined by a structuring element as one used in mathematical morphology. The GLAM is mainly used and studied in synthesis and classification of textures framework but very few works are devoted to the segmentation. The aim of this paper is to exploit the GLAM for the segmentation of textured images. Experiments results over synthetic and real images show the efficiency of the GLAM. The influence of the shape and the size of the structuring element on the segmentation results are also studied.     

A low-noise front-end for multiplexed ENG recording using CMOS technology

Multi-electrode cuffs have been proposed as a means for the parallel recording of naturally-occurring neural signals. Compared to a conventional tripole cuff providing a single channel signal, additional information about the velocity and direction of nerve signals can be extracted from the multi-electrode recordings. Moreover, interference suppression is improved and overall power consumption reduced, as the analysis shows. In this paper a new recording system is proposed, each channel of which consists of a low-noise preamplifier employing lateral bipolar transistors to provide an impedance match to the tissue and a path to ground for the switching currents of a single high-gain amplifier, which is multiplexed between the channels. The proposed system provides low-noise, low-power operation and practically identical channel gains and is suitable for integration in a larger CMOS-based system.