Image sensing model and computer simulation for CCD camera systems

A computational model and a computer simulation system are presented for image sensing in a typical CCD camera system. The computational model makes explicit the sequence of transformations that the light incident on the camera system undergoes before being sensed and recorded. The model is based on a precise definition of input to the camera system that decouples the photometric properties of a scene from the geometric properties of the scene. Based on this model, an interactive research software, the Image Defocus Simulator, has been developed. Application of this software in machine vision research and development is described with examples.     

Are there alternative avian influenza viruses for generation of stable attenuated avian-human influenza A reassortant viruses?

The present study evaluated gull influenza A viruses as donors of attenuating genes for the production of live, attenuated influenza A H1N1 and H3N2 avian-human (ah) reassortant viruses for use as vaccines to prevent disease due to influenza A viruses in humans. The previously evaluated duck influenza A viruses were abandoned as donors of attenuating avian influenza virus genes because clinical evaluation of H1N1 and H3N2 ah reassortant virus vaccines derived from duck viruses documented residual virulence of H1N1 reassortants for seronegative infants and young children. Gull influenza A viruses occupy an independent ecologic niche and are rarely isolated from species other than gulls. The possibility of using gull influenza A viruses as donors of internal gene segments in ah reassortant viruses was evaluated in the present study using three different gull viruses and three human influenza A viruses. Gull-human H3N2 reassortant influenza A viruses with the desired 6-2 genotype (six internal avian influenza virus genes and the two human influenza virus surface glycoprotein genes) were readily generated and were found to be attenuated for squirrel monkeys and chimpanzees. However, ah reassortant viruses with gull and human influenza A H1N1 genes were difficult to generate, and reassortants that had the desired genotype of six gull virus genes with human influenza A H1 and N1 genes were not isolated despite repeated attempts. The gull PB2, NP and NS genes were not present in any of the gull-human H1N1 reassortants generated. The under-representation of these three gene segments suggests that reassortants bearing one or more of these three gene segments might have reduced viability indicative of a functional incompatibility in their gene products. The difficulties encountered in the generation of a 6-2 gull-human H1N1 reassortant virus are sufficient to conclude that the gull influenza A viruses tested would not be useful as donors of sets of six internal genes to attenuate human influenza A viruses. This study also identifies influenza virus gene segments that appear to be incompatible for generation of reassortants. Elucidation of the molecular basis of this restriction may provide information on intergenic interactions involved in virion assembly or packaging.     

Compact Coplanar Waveguide-fed Planar Antenna for Ultra-wideband and WLAN Applications

A novel compact planar antenna is presented for Ultra-wideband (UWB) applications in this paper. The proposed antenna has rectangle-like slot and it is fed by coplanar waveguide. The antenna is printed on FR4 substrate and it has compact size of $28 \times 31 \times 0.8 \,\,\text{ mm}^{3}$ . Parametric study is performed on the antenna by investigating the effect of various geometrical parameters on the frequency characteristics. The antenna is fabricated and measured. It has better return loss response and stable gain over the entire UWB band. The antenna has stable radiation pattern and good impedance matching over entire ultra-wide bandwidth of 3–10.6 GHz. The results show that there is good agreement between measured and simulated results. Various features such as compactness, simple configuration and low fabrication cost make the antenna suitable for UWB and wireless local area network systems.     

Assessment of Extreme Precipitation in Future through Time-Invariant and Time-Varying Downscaling Approaches

Skill of a time-varying downscaling approach, namely Time-Varying Downscaling Model (TVDM), against time-invariant Statistical Downscaling Model (SDSM) approach for the assessment of precipitation extremes in the future is explored. The downscaled precipitation is also compared with a Regional Climate Model (RCM) product obtained from Coordinated Regional Climate Downscaling Experiment (CORDEX). The potential of downscaling the extreme events is assessed considering Bhadra basin in India as the study area through different models (SDSM, TVDM and RCM) during historical period (calibration: 1951–2005, testing: 2006–2012). Next, the changes in precipitation extremes during future period (2006–2035) have been assessed with respect to the observed baseline period (1971–2000), for different Representative Concentration Pathway (RCP) scenarios. All the models indicate an increasing trend in the precipitation, for the monsoon months and maximum increase is noticed using RCP8.5. The annual precipitation during the future period (RCP8.5) is likely to increase by 7.6% (TVDM) and 4.2% (SDSM) in the study basin. An increase in magnitude and number of extreme events during the future period is also noticed. Such events are expected to be doubled in number in the first quarter of the year (January–March). Moreover, the time-invariant relationship (in SDSM) between causal-target variables is needed to be switched with time-varying (TVDM). This study proves that the time-varying property in TVDM is more beneficial since its performance is better than SDSM and RCM outputs in identifying the extreme events during model calibration and testing periods. Thus, the TVDM is a better tool for assessing the extreme events.

     

Chromium dioxide - synthesis and morphology

Chromium dioxide was synthesized by a sealed tube reaction starting from CrO₃ and CaCl₂.2H₂O. Yields of CrO₂ upto 90 percent could be obtained with 7 mole percent of CaCl₂.2H₂O at 360°C for 24 hrs. An ambient pressure of about 30 atm is estimated to be produced by the gases and vapours emitted during the reaction. Under certain conditions, acicular particles with length to width ratio of～10 (constituting～75 percent of the particles) were produced by this procedure.     

Isobaric ternary vapour-liquid equilibria system: Benzene-cyclohexane-n-butanol

Vapour/liquid equilibrium data for the system, benzene-cyclohexane-n-butanol, were obtained at 760 ± 1 mm Hg pressure using a modified Colburn equilibrium still. No ternary azeotrope was observed. The experimental activity coefficient data were correlated with Wohl's three-suffix symmetrical and three-suffix Margules equations with and without using a ternary constant. From an estimate of the average errors in Y¹, Y², and Y³, Wohl's three-suffix Margules equations seem to fit the data fairly well using a ternary constant, C = ?0.1042. From the equilibrium curve drawn for the ternary system on a n-butanol-free basis with percent, n-butanol as parameter, it was found that the azeotrope disappeared at 90–95% n-butanol.     

Analysis of Ethylene Oxide Adducts of Cardanol and 3-Pentadecylphenol by Nuclear Magnetic Resonance and Thin-Layer Chromatography Procedures

Cardanol, a meta-substituted n-long chain (C₁₅) unsaturated alkylphenol derived from cashewnut shell liquid and 3-pentadecylphenol (hydrogenated cardanol) were oxyethylated to various degrees with ethylene oxide under base-catalysed conditions. NMR was used for a rapid determination of the average number of ethoxy groups in the adducts. Homologous adducts of some lower ethoxylates of 3-pentadecylphenol were separated by silica gel thin-layer chromatography and their homogeneity was determined by NMR. The data obtained on 1.2 and 1.7 mole adducts using thin-layer chromatography and NMR showed that the base-catalysed oxyethylation of these alkylphenols proceeded by the formation of the alkylphenoxy ethanol.     

High pressure splitting of castor oil

The effects of variations in pressure (20–40 kg/cm²), oil-to-water ratio (1:0.4–1:1, w/w) and time (0–8 hr) on the extent of hydrolysis of castor oil were studied. Higher pressure, lower oil-to-water ratio and longer duration gave higher percentage splits. At 40 kg/cm² pressure and an oil-to-water ratio of 1:1, ca. 92% split was obtained in 8 hr. When the oil was hydrolyzed in 2 stages at 20 kg/cm² with an oil-to-water ratio of 1:0.4, ca. 96% split was obtained in a total period of 10 hr. Splitting at 20 kg/cm² gave minimal amounts of dienoic acids because of the decomposition of estolides.     

Electrical conductivity of pure and CaO-doped ThO2 ceramics

The a. c. total conductivity (σ) of pure and CaO-doped thoria samples has been measured in air in the temperature range of 600 to 1400°C. For each sample, the activation energy for conduction has been calculated from a plot of σ T vs. 1/T, where T is absolute temperature. The present results have been compared with those existing on both ThO₂-CaO and ThO₂-YO_1.5 ceramics.     

A multiview 3D modeling system based on stereo vision techniques

This paper introduces a stereo vision system to automatically generate 3D models of real objects. 3D model generation is based on the merging of multiview range images obtained from a digital stereo camera. Stereo images obtained from the camera are rectified, and a correlation-based stereo matching technique reconstructs range images from them. A turntable stage is also employed to obtain multiple range images of the objects. To register range images into a common coordinate system automatically, we introduce and calibrate a turntable coordinate system with respect to the camera coordinate system. After the registration of multiview range images, a 3D model is reconstructed using a volumetric integration technique. Error analysis on turntable calibration and 3D model reconstruction shows the accuracy of our 3D modeling system.Received: 2 August 2003, Accepted: 20 September 2004, Published online: 25 February 2005 Correspondence to: S.Y. Park