Estimating Internet Users' Demand Characteristics

We investigate two parametric approaches and one non-parametric approach toestimating Internet users' value-of-time, an important characteristic ofdemand for Internet services. The advantages of these approaches are madeclear and their limitations discussed. The models are tested with datagenerated from our similation model of the Internet economy. Given thecharacteristics of the data, we investigate parametric count-data modelsfirst. While reasonably good results are obtained on all medium- andlarge-sized jobs, the method fails on small-sized ones. Second, we develop anonparametric quasi-Bayesian update algorithm for retrieving the underlyingdistribution function of Internet users' value-of-time purely fromobservations on their choices. Compared with the parametric count-data models,good results are obtained in every case.     

Schmelzen und Behandeln von Metallen und Legierungen im Vakuum

The growing demands for better quality of metallic materials can only be met by the application of vacuum during the production of these metals and alloys and their field of application.     

Influence of Interfacial LSMO Nanoparticles/Layer on the Vortex Pinning Properties of YBCO Thin Film

YBa₂Cu₃O_7?δ (YBCO) thin films have been deposited on bare and La_0.67Sr_0.33MnO₃ (LSMO) modified single crystal SrTiO₃ (STO) substrates. The effect of randomly distributed ferromagnetic LSMO nanoparticles and a complete LSMO layer, present at STO/YBCO interface, on the superconducting properties of YBCO thin films has been investigated by temperature dependent magnetization studies. The YBCO thin film on LSMO nanoparticles decorated STO substrate shows significant improvement in the critical current density and pinning force density as compared to the YBCO thin film deposited on bare STO substrate and this improvement is more significant at higher applied magnetic field. However, the LSMO/YBCO bilayer showed the improved flux pinning properties only up to a magnetic field of 1.5 T above which it deteriorates. In the case of LSMO/YBCO bilayer, the underlying LSMO layer gives rise to magnetic inhomogeneities due to domain structure, which leads to improved flux pinning properties limited to lower field. However, in the case of LSMO nanoparticles decorated substrate, the presence of LSMO nanoparticles at YBCO/STO interface seems to introduce magnetic inhomogeneities as well as structural defects, which might be acting as correlated pinning sites leading to improved flux pinning properties of the YBCO thin film over a wide range of applied magnetic field.     

High power and low cross‐polarization microstrip patch array antenna at S‐band

This article reports the design and development of high power, low cross‐polarization, and high efficiency circularly polarized microstrip patch array antenna at S‐band, proposed for Indian Regional Navigation Satellite System payload. A novel feeding mechanism for truncated corner square patch based on square coaxial line for broadband impedance matching is discussed. Sequential rotation scheme for axial ratio improvement in an array is implemented. High power handling margins in critical regions of square coaxial line for multipaction breakdown is brought out. Measured 19 dB return loss bandwidth of array antenna is 15.6%. Axial ratio of 0.78 dB over global coverage is achieved in the desired frequency band of operation. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012.     

Retention and Distribution of 1-Naphthol and Naphthol Polymerization Products on Surface Soils

Sorption and extractability of naphthol and naphthol polymerization products (NPP) were evaluated in two surface soils. NPP were generated by the addition of horseradish peroxidase and H2O2 to naphthol solutions in contact with the surface soils. While NPP retention on the forest soil was lower compared to the parent naphthol, no difference in sorption of naphthol and NPP was observed in the agricultural soil. The agricultural soil retained more naphthol and NPP than the forest soil. The NPP sorption behavior noted in this study was in contrast to that of phenol polymerization products observed by other researchers. The presence of phenol and 2,4-dichlorophenol as cosolutes had no significant impact on naphthol or NPP retention on the two soils, and naphthol was more easily extracted from both soils whenever phenol was present as a cosolute. Characterization of the naphthol polymerization products using reverse-phase high-pressure liquid chromatography and octanol-water partitioning indicated that significant fractions of the water-soluble and insoluble NPP were comprised of oligomers that were more polar than the parent 1-naphthol. This decrease in polarity upon polymerization is believed to have been responsible for the NPP retention and binding behavior observed in this study.     

Reactive ion etching of trenches in 6H-SiC

In this paper, we report the reactive ion etching (RIE) of trenches in 6H-silicon carbide using SF₆/O₂. The plasma parameters: etchant composition, gas flow rate, chamber pressure, and radio frequency power were optimized to obtain a maximum etch rate of 360Å/min. The etch rate of SiC was found to exhibit a direct correlation with the dc self bias except when the O₂ percentage was varied. Trenches were fabricated using the optimized conditions. It was found that the trench surface was extremely rough due to the aluminum micromasking effect. To overcome this effect, a Teflon^TM sheet was used to cover the cathode during the experiment. The trenches fabricated using this modification were found to have smooth etched surfaces and sidewalls. The angle of anisotropy of these trenches was approximately 80° which is suitable for device applications.     

De-agglomeration of thorium oxalate - a method for the synthesis of sinteractive thoria

Thorium oxalate was obtained by precipitation in water and in non-aqueous solvents and de-agglomerated by ultrasonication in both aqueous as well as non-aqueous media. Sinteractive thoria (crystallite size 6-20 nm) obtained from the de-agglomerated thorium oxalate was characterised for residual carbon, crystallite size, specific surface area, particle size distribution and bulk density. Microstructure of the precursor and the product was studied using TEM and HRTEM. The morphology of the sintered pellets was studied using SEM. The reactivity of the calcined powders was determined by measuring the density of the sintered compacts. The solvent used for de-agglomeration was found to have significant influence on the microstructure of the powders. Thoria derived through aqueous precipitation route could be sintered to a density of 9.7 Mg m⁻³ at 1673 K. It was demonstrated that ultrasonic de-agglomeration could be a useful method for obtaining sinteractive thoria.     

Biomass and energy production in Casuarina equisetifolia plantation stands in the degraded dry tropics of the Vindhyan plateau, India

Two age groups of Casuarina equisetifolia (Forst.) plantation stands in the Renukoot forest division of the Vindhyan plateau were investigated over the span of three years for total and component biomass, annual net primary production, energy storage and annual net energy fixation. A high range of biomass (44–81 t ha⁻¹) was recorded in a densely populated stand at ages 5–7 years in comparison to a sparsely populated stand at ages 8–10 years. The contribution of the hole component gradually increased with increasing diameter class while foliage and branch components had a large proportion of biomass in the lower diameter classes. Maximum litterfall occurred in May and foliage litter contributed 87–95% of total litterfall. The energy content and storage in component parts were higher than some other promising tree species for energy plantation in the dry tropics. Production estimates of 19–29 t ha⁻¹ yr⁻¹ showed that the performance of Casuarina is good for dry tropical conditions. The biomass accumulation ratio and production efficiency showed a significant positive and negative (logarithmic) relationship, respectively with plantation age. The energy conserving efficiency of the 5-year old stand was more than twice that of the 8-year old stand.