Conducting composites of polythiophene and polyfuran with acetylene black

Conducting composites of polythiophene (PTP) and polyfuran (PF) with acetylene black (AB) were prepared via chemical oxidative polymerization of thiophene and furan in a suspension of AB in CHCl₃ at room temperature using anhydrous FeCl₃ as the oxidant. Formation of PTP and PF and their subsequent incorporation in PTP–AB and PF–AB composite systems were confirmed by FTIR analysis. Scanning electron microscope analysis showed the presence of compact clusters of particles in both composites. Transmission electron micrographs of PTP–AB and PF–AB composites showed formation of globular polymer encapsulated AB particles with average diameters of the order of ～100 nm in both systems. Thermogravimetric analysis revealed that the overall thermal stability varied in the order: AB > PTP–AB > PTP and AB > PF–AB > PF. DC conductivity values for the PTP–AB and PF–AB composites were of the order of 10^?2 and 10^?3 S cm^?1, respectively. Copyright © 2004 Society of Chemical Industry     

Initiation of air core in a swirl nozzle using time-independent power-law fluids

Summary Theoretical and experimental analyses have been carried out for determining the injection condition below which the formation of air core does not take place in the course of flow of a time-independent power-law fluid through a swirl nozzle. Analytical solution lends one distinct value of generalized Reynolds number at the inlet to a nozzle below which the air core is not formed. Experiments reveal that there exist two limiting values of such generalized Reynolds number regarding the formation of air core in a nozzle. One value being the upper limit below which steady flow occurs without air core, the other one is the lower limit above which steady flow with fully developed air core persists. In between these two limiting values, there prevails a transition zone through which fully developed air core is set up within the nozzle. For all the nozzles, theoretical results are in fair agreement with the experimental values of upper limit of generalized Reynolds numbers with respect to steady flow without air core. Amongst all the pertinent independent geometrical parameters of a nozzle, the orifice-to-swirl chamber-diameter ratio has the remarkable influence on generalized Reynolds number describing the initiation of air core.Nomenclature D ₁ Swirl chamber diameter - D ₂ Orifice diameter - D _s Diameter of tangential entry ports - E A non-dimensional parameter defined by Eq. (9) - E _R A non-dimensional parameter defined by Eq. (25) - K Flow consistency index - L ₁ Length of the swirl chamber - n Flow behaviour index - P Static pressure inside the nozzle - P _b Back-pressure of the nozzle - Q Volume flow rate - R Radius vector or longitudinal coordinate with respect to spherical coordinate system (Fig. 3) - R ₁ Radius of the swirl chamber - R ₂ Radius of the orifice - Generalized Reynolds number at the inlet to the nozzle - Limiting value of generalized Reynolds number describing initiation of air core - R _z Radius at any section - r Radial distance from the nozzle axis - r _a Air core radius - u Longitudinal component of velocity with respect to spherical coordinate system (Fig. 3) - V _r Radial velocity component - V _z Axial velocity component - V Tangential velocity component - Tangential velocity at inlet to the nozzle - v Component of velocity in the axial plane perpendicular toR (Fig. 3) - w Component of velocity perpendicular to axial plane with respect to the spherical coordinate system (Fig. 3) - z Distance along the nozzle axis from its inlet plane - Half of the spin chamber angle - Boundary layer thickness measured perpendicularly from the nozzle wall - ₂ Boundary layer thickness at the orifice - Angle, which a radius vector makes with the nozzle axis, in spherical coordinate system (Fig. 3) - Density of the fluid - Running coordinate in the azimuthal direction with respect to the cylindrical polar coordinate system as shown in Fig. 3 - Circulation constant With 8 Figures     

Electrical properties of vanadium pentoxide doped with lithium and sodium in the α-phase range

The electrical conductivity and Seebeck coefficients have been measured from room temperature to 500° C for polycrystalline V₂O₅ and V₂O₅ doped with lithium and sodium in the -phase range. The conductivity increases with doping and the energy of activation decreases. The Seebeck coefficient indicates that electrons are the majority carriers. The results have been discussed in terms of the two-level hopping model.     

Characteristics of p-Ge/N-GaAs heterojunctions grown by molecular beam epitaxy

Reports the nearly ideal electrical characteristics of p-Ge/N-GaAs heterojunction diodes grown by molecular beam epitaxy. The temperature and device size dependencies of the current-voltage characteristics have been investigated. At room temperature, unity ideality factor has been demonstrated over almost six decades of current.<>     

The cluster scanning system

Users with severe physical impairment often use computers with one or two switches using a scanning system. Scanning is a technique of successively highlighting portions of screen. This paper presents a new scanning system that works through clustering screen objects. The system is initially calibrated through simulation and later validated through a user trial. Results show that it outperforms existing block scanning systems.     

Effect of dysprosia doping on structural and electrical property of stabilized zirconia for intermediate- temperature SOFCs

Present work deals with structural, micro-structural and electrical properties of dysprosia stabilized zirconia electrolyte, which have been evaluated by means of X-ray diffraction (XRD) and scanning (SEM), and complex impedance analysis respectively. The amount of dysprosia was varied from 2 to 12 mol% in zirconia. The addition of dysprosia (8-12 mol%) stabilized the cubic zirconia phase, which was analyzed from XRD analysis. SEM micrographs clearly showed the improvement in sinterability with increase in dysprosia concentration up to 6 mol% disprosia. Complex impedance analysis was performed in the temperature range from 250 to 600 °C. The results indicated a gradual decrease in impedance of both bulk and grain boundary and increase in conductivity with dysprosia doping up to 6 mol% and thereafter showing a reverse trend. The activation energies for oxygen ion migration were also found to decrease with increase in dysprosia doping which was in the range of 0.99 ? 1.28 eV. The average thermal expansion coefficient increases linearly.     

Intercarrier bandwidth exchange: an engineering framework

A mismatch between demand and supply for bandwidth is common in transport carrier networks. This mismatch is generally a result of the disparity between a carrier's capacity buildout and its anticipated customer demand. A carrier with temporary bandwidth deficit or lack of presence in a geographical region and a carrier with surplus capacity in the right locations can be brought together by the emerging bandwidth exchange technology. Bandwidth exchange offers a win-win solution, in which the carrier with a deficit avoids losing revenue by buying capacity from the carrier with surplus, and the latter makes additional revenue by retail sale of its excess capacity. While the concept of real-time purchase and exchange of bandwidth has attracted a lot of attention, many technical challenges stand in the way of making it a reality. The purpose of this article is to provide an engineering framework for enabling real-time bandwidth exchange with committed quality of service and service level agreement among transport carriers. Special emphasis is given to identifying the architectural requirements and the enabling infrastructure necessary for building a viable bandwidth exchange that can be used for creating revenue out of surplus stranded capacity. Indepth analysis of cross-carrier service level agreement specification, capacity publication, route design, and service provisioning are also provided in the article.     

An automated patient monitoring using discrete‐time wireless sensor networks

In recent years, Internet of Things (IoT) devices are used for remote health monitoring. For remotely monitoring a patient, only the health information at different time points are not sufficient; predicted values of biomarkers (for some future time points) are also important. In this article, we propose a powerful statistical model for an efficient dynamic patient monitoring using wireless sensor nodes through Bayesian Learning (BL). We consider the setting where a set of correlated biomarkers are measured from a patient through wireless sensors, but the sensors only report the ordinal outcomes (say, good, fair, high, or very high) to the sink based on some prefixed thresholds. The challenge is to use the ordinal outcomes for monitoring and predicting the health status of the patient under consideration. We propose a linear mixed model where interbiomarker correlations and intrabiomarker dependence are modeled simultaneously. The estimated and the predicted values of the biomarkers are transferred over the internet so that health care providers and the family members of the patient can remotely monitor the patient. Extensive simulation studies are performed to assess practical usefulness of our proposed joint model, and the performance of the proposed joint model is compared to that of some other traditional models used in the literature.