Observation of colloidal growth in coal-derived liquids

Heavy direct coal liquefaction products are known to exhibit rapidly increasing viscosities upon prolonged exposure to oxygen. Small-angle X-ray scattering has been used to monitor changes in the colloidal structure of a coal liquid subjected to accelerated aging under an oxygen atmosphere for a total period of 54 days. The data are consistent with an agglomeration model for the formation of large colloidal-size scattering centres which are partially responsible for the rapidly increasing viscosity of the coal liquid.     

Tweet-scan-post: a system for analysis of sensitive private data disclosure in online social media

Knowledge and Information Systems - The social media technologies are open to users who are intended in creating a community and publishing their opinions of recent incidents. The participants of...     

Low Dielectric Loss Polytetrafluoroethylene/TeO2 Polymer Ceramic Composites

TeO₂ particle-filled PTFE composites were prepared by the powder processing technique. The structure and microstructure of the composites were investigated by X-ray diffraction and scanning electron microscopic methods. The effect of the ceramic content (0–0.6 volume fraction) of TeO₂ on the dielectric properties of the composites was studied at 1 MHz and 7 GHz. The dielectric constant and dielectric loss increased with an increase in the TeO₂ content. For 60 vol% of TeO₂, the composite has a dielectric constant of 5.4 and a loss tangent of 0.006 at 7 GHz. The measured dielectric constant (ɛ_r) is compared with the effective dielectric constant calculated using different theoretical models. The observed dielectric constants are in agreement with that calculated using effective medium theory. The coefficient of thermal expansion of the composites decreases with the TeO₂ content, reaching a minimum of 32 ppm/°C for 60 vol% loading.     

Synthesis, spectroscopic characterization, and thermal decomposition kinetics of some lanthanide(Ⅲ) nitrate complexes of 2-(N-o-hydroxyacetophenone) amino-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene

Complexes of La(Ⅲ), Ce(Ⅲ), Pr(Ⅲ), Nd(Ⅲ), Sm(Ⅲ), Eu(Ⅲ), Gd(Ⅲ), Dy(Ⅲ), Yb(Ⅲ), and Lu(Ⅲ) with 2-(N-o- hydroxyacetophenone)amino-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene (HAAT) formed by the condensation of o-hydroxyacetophenone and 2-amino-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene were synthesized and characterized on the basis of elemental analyses, molar conductance measurements, magnetic susceptibility data, UV-Visible, IR, and NMR spectral studies. The spectral data revealed that the ligand acted as a neutral tridentate coordinating to the metal ion through ONO donor sequence. A coordination number nine was proposed for the complexes. Thermal decomposition studies of the ligand and lanthanum(Ⅲ) complex were carried out and kinetic parameters were calculated using Coats-Redfern equation. The decomposition reactions followed random nucleation mechanism with one nucleus on each particle.     

Epoch Extraction by Phase Modelling of Speech Signals

Epochs are instants of significant excitation of vocal-tract system in speech production process. In this paper, we attempt to extract information about epochs from phase spectra of speech signals. The phase spectrum of speech is modelled as the response of an allpass (AP) filter, and the resulting error signal is used for epoch extraction. The parameters of AP model are estimated by imposing sparsity constraints on the error signal. The error signal, thus obtained, exhibits prominent peaks at epoch locations. The epochal candidates obtained from the error signal are refined using a dynamic programming algorithm. The performance of the proposed method is consistent across genders and is comparable with the state-of-the-art methods.     

Compact wideband Koch fractal printed slot antenna

A compact wideband printed slot antenna, suitable for wireless local area network (WLAN) and satisfying the worldwide interoperability for microwave access (WiMAX) applications, is proposed here. The antenna is microstrip-fed and its structure is based on Koch fractal geometry where the resonance frequency of a conventional triangular slot antenna is lowered by applying Koch iterations. The antenna size inclusive of the ground plane is compact and has a wide operating bandwidth. The proposed second iteration Koch slot antenna operates from 2.33 to 6.19 GHz covering the 2.4/5.2/5.8 GHz WLAN bands and 2.5/3.5/5.5 GHz WiMAX bands. The antenna exhibits omnidirectional radiation coverage with a gain better than 2.0 dBi in the entire operating band. Design equations for the proposed antenna are developed and their validity is confirmed on different substrates and for different slot sizes.     

A Comparative Study of Digital Self-interference Cancellation Techniques in In-Band Full-Duplex OFDM Systems

Wireless Personal Communications - In-Band Full-Duplex is a powerful technique which theoretically doubles the spectral efficiency. It significantly contributes to the ever-increasing demand for...     

Compact planar multiband antenna for GPS, DCS, 2.4/5.8 GHz WLAN applications

A compact single-feed multiband planar antenna configuration suitable for GPS, DCS, 2.4/5.8 GHz WLAN applications is presented. The antenna has dimensions 38/spl times/3/spl times/1.6 mm and offers good radiation and reflection characteristics in the above frequency bands. The antenna has a simple geometry and can be easily fed using a 50 /spl Omega/ coaxial probe.