Use of tanninsulfonic acid in the synthesis of water‐dispersible polyaniline

Polyaniline was synthesized in the presence of tanninsulfonic acid to yield a product tanninsulfonic acid‐doped polyaniline (TANI‐PANI) that is water‐dispersible. Several samples ranging from 0 to 70% tanninsulfonate (TS) were prepared. These samples were then evaluated for differences in dispersibility, particle size, and conductivity. As the percent of TS in the samples was increased, the water‐dispersibility of the TANI‐PANI also increased. The particle size of the samples as well as the conductivity of the samples decreased with increasing percentages of TS in the samples. After extensive washings, however, the conductivity remained fairly constant (～0.5 S/cm) regardless of the amount of TS in the samples. Additionally, elemental analysis, TGA, and IR data were used to demonstrate that the TS may be grafted to polyaniline during the synthesis of TANI‐PANI. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2113–2119, 2007     

Thermal decomposition as route for silver nanoparticles

Single crystalline silver nanoparticles have been synthesized by thermal decomposition of silver oxalate in water and in ethylene glycol. Polyvinyl alcohol (PVA) was employed as a capping agent. The particles were spherical in shape with size below 10 nm. The chemical reduction of silver oxalate by PVA was also observed. Increase of the polymer concentration led to a decrease in the size of Ag particles. Ag nanoparticle was not formed in the absence of PVA. Antibacterial activity of the Ag colloid was studied by disc diffusion method.     

Alkylation of naphthalene with alcohols over mesoporous MCM-41

Mesoporous MCM-41 is found to promote alkylation of naphthalene by alcohols. In addition to the preferred branched side chain productsn-alkylated product is also observed in the case of propylation of naphthalene.     

Vibration of antisymmetric angle-ply composite annular plates of variable thickness

Journal of Mechanical Science and Technology - Based on first order shear deformation theory, free vibrational behaviour of antisymmetric angle-ply composite annular plate is investigated. The...     

Parallelization of a dynamic SVD clustering algorithm and its application in information retrieval

We describe an implementation of a parallel document clustering scheme based on latent semantic indexing, which uses singular value decomposition. Given a set of documents, the clustering algorithm is dynamic in the sense that it automatically infers the number of clusters to be output. The parallel version has been implemented on a LAN and on a dual‐core system. Experimental evaluation of the algorithm shows an average speed‐up of 6.22 for the LAN implementation and an average speed‐up of 3.71 for the dual‐core implementation, while still maintaining a precision and recall in the range [0.85, 1]. To put these implementations in the context of information retrieval, we use the parallel clustering algorithm and develop a document similarity search system. The similarity search system shows good performance in terms of precision and recall. Copyright © 2010 John Wiley & Sons, Ltd.     

Impact of Channel Errors on Decentralized Detection Performance of Wireless Sensor Networks: A Study of Binary Modulations, Rayleigh-Fading and Nonfading Channels, and Fusion-Combiners

We provide new results on the performance of wireless sensor networks in which a number of identical sensor nodes transmit their binary decisions, regarding a binary hypothesis, to a fusion center (FC) by means of a modulation scheme. Each link between a sensor and the fusion center is modeled independent and identically distibuted (i.i.d.) either as slow Rayleigh-fading or as nonfading. The FC employs a counting rule (CR) or another combining scheme to make a final decision. Main results obtained are the following: 1) in slow fading, a) the correctness of using an average bit error rate of a link, averaged with respect to the fading distribution, for assessing the performance of a CR and b) with proper choice of threshold, on/off keying (OOK), in addition to energy saving, exhibits asymptotic (large number of sensors) performance comparable to that of FSK; and 2) for a large number of sensors, a) for slow fading and a counting rule, given a minimum sensor-to-fusion link SNR, we determine a minimum sensor decision quality, in order to achieve zero asymptotic errors and b) for Rayleigh-fading and nonfading channels and PSK (FSK) modulation, using a large deviation theory, we derive asymptotic error exponents of counting rule, maximal ratio (square law), and equal gain combiners.     

A Low-Supply-Voltage CMOS Sub-Bandgap Reference

A low-power (21 $muhbox{W}$ ) bandgap reference source that is operable from a nominal supply voltage of 1.4 V is described. The circuit provides an output voltage equal to the bandgap voltage having a low output resistance and allows resistive loading. It does not use resistors or operational amplifiers. Thus, the design is suitable for fabrication in any digital CMOS technology. The circuit uses a current conveyor and current mirrors to convert the proportional to absolute temperature voltage into a current using a MOSFET. The current is converted back to a voltage by using the functional inverse of the FET $v-i$ characteristics. This makes the voltage gain linear and temperature independent. The absence of back-gate bias is the reason for achieving the low supply voltage of operation. Simulation results using the transistor models for the 0.18-$mu$m TSMC process show that the voltage-variation over the temperature range 0 to 100 $^{circ} {hbox {C}}$ is $≪$1 mV.      

An Artificial-Neural-Network-Based Integrated Regional Model for Rain Retrieval Over Land and Ocean

An integrated regional model is proposed for rain-rate retrievals over land/ocean from the brightness temperature (Tb) values of the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI). The polarization-corrected temperature calculated from the 85.5-GHz channels is also considered as one of the inputs along with the nine channel Tb values. This model is applicable over the region between and . For this purpose, an artificial neural network is utilized. The collocated precipitation radar (PR) near-surface rain rates as given by a 2A25 data product is considered as a target value. The methodology consists of the separation of land and ocean pixels, the separation of stratiform and convective pixels over land/ocean, and the selection of important features (inputs) for the multilayer perceptron network by the feature selection technique for each group. For the separation of land/ocean pixels, the Tb values of the 10.65-GHz vertical channel are utilized. The values are utilized to separate the stratiform and convective pixels both over land and ocean. The rain retrieval from the developed model is validated with TRMM PR. Overall result shows the better agreement of the model-retrieved rain rate with the PR observation compared to the TMI (2A12) rain rate particularly over land. The rain retrieved from the developed model is further validated with Doppler weather radar. A reasonably good agreement is observed between these two estimations.     

Ion beam and thermally-induced interface reaction between highT c superconductor thin film and metal overlayer

Ion beam and thermally-induced interface reactions between highT _c superconducting thin film of Y₁Ba₂Cu₃O_7−x and metal overlayer of Ag are studied with a view to control the interfacial property of contact resistance. The interface reaction is induced by 100 keV Ar⁺ ion beam with different ion dose values ranging from 5 × 10¹³ to 3×10¹⁴ ions/cm². The YBaCuO film-metal interface is characterized by using the small angle XRD to study the structural properties of the interfacial phases. The electrical property of the interface, specifically contact resistance, has been investigated for different dose values and thermal treatments. Three-probe vs four-probe configuration has been adopted to measure the contact resistance.