A 500-W coupled-cavity TWT for Ka-band communication

Worldwide demand for high-power amplifiers for digital satellite communication at Ka-band frequencies between 27 and 31 GHz is steadily increasing (2003). Communication and Power Industries (CPI) has developed a 500-W periodic permanent magnet focused coupled-cavity traveling wave tube (TWT) for conduction-cooled amplifier systems, which is being introduced into the commercial satellite communication market. The TWT is capable of greater than 500-MHz instantaneous bandwidth and is cathode voltage tunable from 28.3 to 30 GHz. The TWT may be operated saturated at the 500-W output power level or backed off from saturation in the linear mode. CPI's Satcom Division has integrated the TWT into a conduction-cooled transmitter box suitable for antenna hub-mount applications. The amplifier uses predistortion networks to provide a high degree of linear response when operated in output power back-off mode.     

Modeling methyl methacrylate free radical polymerization: Reaction in hydrophilic nanopores

In previous work, we developed a simplified model for the diffusion controlled bulk polymerization of methyl methacrylate and extended the model to capture the reaction under nanoconfinement. The calorimetric conversion versus time data in bulk and in silanized hydrophobic nanopores was well captured by the model. Here we further extend the model to capture the reaction in native hydrophilic controlled pore glass (CPG) nanopores accounting for catalysis by surface silanol groups. The ability of the model to describe experimental data is tested. In order to fit the data, the parameters describing monomer and active chain diffusion differ from that in hydrophobic pores.     

Joint learning and weighting of visual vocabulary for bag-of-feature based tissue classification

Automated classification of tissue types of Region of Interest (ROI) in medical images has been an important application in Computer-Aided Diagnosis (CAD). Recently, bag-of-feature methods which treat each ROI as a set of local features have shown their power in this field. Two important issues of bag-of-feature strategy for tissue classification are investigated in this paper: the visual vocabulary learning and weighting, which are always considered independently in traditional methods by neglecting the inner relationship between the visual words and their weights. To overcome this problem, we develop a novel algorithm, Joint-ViVo, which learns the vocabulary and visual word weights jointly. A unified objective function based on large margin is defined for learning of both visual vocabulary and visual word weights, and optimized alternately in the iterative algorithm. We test our algorithm on three tissue classification tasks: classifying breast tissue density in mammograms, classifying lung tissue in High-Resolution Computed Tomography (HRCT) images, and identifying brain tissue type in Magnetic Resonance Imaging (MRI). The results show that Joint-ViVo outperforms the state-of-art methods on tissue classification problems.     

Computation of Structural,Mechanical, Thermal,and Magnetic Characteristics of Newly Designed Quaternary Heusler Alloys CoNbCrZ (Z = Al,Ga, Si,Ge)

Journal of Superconductivity and Novel Magnetism - First-principles calculations accomplished to investigate structural, mechanical, thermal and magnetic properties of newly designed CoNbCrZ...     

Source identification of fine particles in Washington, DC, by expanded factor analysis modeling

An expanded factor analysis model (ME-2) that is capable of taking into account the influence of independent variables such as wind speed, wind direction, time of year and other variables of the measured fine particle matter (PM2.5) concentration data was utilized for identifying sources of airborne pollutants and providing quantitative estimations of the contribution of each source. The chemical composition data used in this study were obtained from PM2.5 samples collected using the Interagency Monitoring of Protected Visual Environments samplers from August 1999 to December 2001 at an urban monitoring site in Washington, DC. The expanded model has been applied to two different data sets based on the particulate carbon variables. Such an approach had been successfully applied previously and provided improved source resolution in simulated and ambient concentration data. Initially, total OC and EC were used in the expanded model and were compared to the results using conventional positive matrix factorization that had been done previously using the individual carbon fractions data. In the other expanded model analysis, the eight carbon fractions were used during the modeling in order to ascertain if additional source information could be extracted from the data. In both cases, it was possible to separate diesel from spark-ignition vehicles. The use of the individual carbon fractions in the model provides information on what appears to be secondary organic aerosol formation.     

Timed activity studies for assessing the energy expenditure of women from an urban slum in south India

Time-disposition studies are necessary for computing energy requirements of populations. This study captures the rich information on the timed activity pattern of adult women from poor households engaged in home-based work. We studied 34 women beedimakers (cigarette makers), 21 tailors, and 34 homemakers. Data were collected by direct observation of the women's activities on a typical day. Time spent on related activities was pooled and classified as sleep, household work, child care, occupational work, and residual work. These were further categorized on the basis of our published work on the energy cost of women's activities and the World Health Organization (WHO) classification of occupational activities as sedentary, moderate, and heavy. Most of the household activities could be classified as moderate to heavy (> 2.2 times basal metabolic rate [BMR]). Childcare activities were distributed on a scale from sedentary to heavy, whereas occupational activities, such as beedimaking and tailoring, were sedentary (< 2.2 BMR). Homemakers spent significantly more time on moderate to heavy work (p < .05) than beedimakers and tailors. Women working for income spent only four to six hours on occupational work, which was possible because they reduced the time spent on heavy work (i.e., housework), and reduced the time on personal care. Still, more than 80% of women could not put in eight hours of paid work. Thus, women in the home-based sector constantly negotiate among time spent on heavy household work, child care, and occupational work in order to continue in the labor market.     

Synthesis of molybdenum (IV) sulphide: Part II. Reaction of molybdenum (VI) oxide with (a) zinc sulphide and (b) cadmium sulphide in the presence of ammonium chloride

Reactions of molybdenum (VI) oxide with (a) zinc sulphide and (b) cadmium sulphide were studied in the temperature range 723–973 K. Small amounts of mixtures of molybdenum (IV) sulphide and molybdenum (IV) oxide, which are difficult to separate, were produced. When ammonium chloride was added to the reactants, 89.1% pure MoS₂ at 773 K and 96.17% pure MoS₂ at 798 K were produced in the case of zinc sulphide and cadmium sulphide respectively.     

Sesame seed as an alternative plant protein source: A comprehensive physicochemical characterisation study for alkaline,salt and enzyme-assisted extracted samples

Sesame seed is mostly utilised for its oil but also the waste of the oil processing; the seed meal has also significant potential to be used as an alternative protein source. In this study, the goal is to produce sesame seed protein by using three different techniques; alkaline, salt and enzyme-assisted extraction. A comprehensive physicochemical characterisation of the extracts was performed. Total and soluble protein contents, emulsification activity & emulsion stability, FTIR spectroscopy, hydration behaviour and gelling ability experiments by TD-NMR were conducted for all extracted proteins. Also, SDS-PAGE experiments were performed to observe the effect of extraction conditions on protein folding. Overall, the aqueous phase of enzyme-assisted extracted proteins (E-ACP) had the highest protein content and solubility, which resulted in other improved physicochemical properties. Salt extracted samples were ‘salted-out’, therefore, had poor physicochemical properties. TD-NMR experiments further confirmed the solubility and gelling ability results by measuring the change in the T₂ spin relaxation times. Additionally, FTIR spectroscopy confirmed the most critical peaks for the proteins; Amide I (C=O stretching) and Amide II (N–H bending). In summary, depending on the physicochemical property of interest, different extraction methods yielded proteins with different properties.