Performance Analysis Over Unified Generalized Composite Fading Model

With the deep study of the Hamming distances of orthogonal arrays (OAs), the application of OAs has penetrated into many fields, one of which is to construct the key predistribution schemes (KPSs) for distributed sensor networks.In this paper, we define the Hamming distance distribution (HDD) of an OA and its uniqueness. Furthermore, we present some OAs with unique HDD. In KPSs based on these OAs, the calculations of metrics for evaluating connectivity and resilience can be simplified. We also illustrate that KPSs based on them have a wider application and better connectivity and resilience than the existing ones.

     

Estimation of Mine Water Quantity: Development of Guidelines for Indian Mines

Mine Water and the Environment - There are no available guidelines in India for estimating the quantity of mine water in an operational mining pit. Based on multiple case studies, procedures to...     

Finite element implementation of Maxwell's equations for image reconstruction in electrical impedance tomography

Traditionally, image reconstruction in electrical impedance tomography (EIT) has been based on Laplace's equation. However, at high frequencies the coupling between electric and magnetic fields requires solution of the full Maxwell equations. In this paper, a formulation is presented in terms of the Maxwell equations expressed in scalar and vector potentials. The approach leads to boundary conditions that naturally align with the quantities measured by EIT instrumentation. A two-dimensional implementation for image reconstruction from EIT data is realized. The effect of frequency on the field distribution is illustrated using the high-frequency model and is compared with Laplace solutions. Numerical simulations and experimental results are also presented to illustrate image reconstruction over a range of frequencies using the new implementation. The results show that scalar/vector potential reconstruction produces images which are essentially indistinguishable from a Laplace algorithm for frequencies below 1 MHz but superior at frequencies reaching 10 MHz.     

Peptides Containing meso-Oxa-Diaminopimelic Acid as Substrates for the Cell-Shape-Determining Proteases Csd6 and Pgp2

The enzymes Csd6 and Pgp2 are peptidoglycan (PG) proteases found in the pathogenic bacteria Helicobacter pylori and Campylobacter jejuni, respectively. These enzymes are involved in the trimming of non-crosslinked PG sidechains and catalyze the cleavage of the bond between meso-diaminopimelic acid (meso-Dap) and d -alanine, thus converting a PG tetrapeptide into a PG tripeptide. They are known to be cell-shape-determining enzymes, because deletion of the corresponding genes results in mutant strains that have lost the normal helical phenotype and instead possess a straight-rod morphology. In this work, we report two approaches directed towards the synthesis of the tripeptide substrate Ac-iso-d -Glu-meso-oxa-Dap-d -Ala, which serves as a mimic of the terminus of an non-crosslinked PG tetrapeptide substrate. The isosteric analogue meso-oxa-Dap was utilized in place of meso-Dap to simplify the synthetic procedure. The more efficient synthesis involved ring opening of a peptide-embedded aziridine by a serine-based nucleophile. A branched tetrapeptide was also prepared as a mimic of the terminus of a crosslinked PG tetrapeptide. We used MS analysis to demonstrate that the tripeptide serves as a substrate for both Csd6 and Pgp2 and that the branched tetrapeptide serves as a substrate for Pgp2, albeit at a significantly slower rate.     

Electro-Discharge Machining of Inconel 825 Super alloy: Effects of Tool Material and Dielectric Flushing

Aspects of machinability of Inconel 825 super alloy during electro-discharge machining was attempted in this work. The extent of machinability was investigated in purview of process performance (i.e. material removal rate), surface integrity (morphology as well as topography) of the EDMed work surface including surface roughness, surface crack density, white layer thickness, and micro-indentation hardness. Effects of variation of tool material (graphite, tungsten, brass and copper) were analyzed in this work. Metallurgical characteristics of the EDMed work surface were studied in view of phase information (matrix and precipitates), grain refinement (crystallite size, micro-strain and dislocation density) etc. Results were further interpreted in support of EDS, and micro-hardness test data. Additionally, effects of flushing condition (with and without flushing) of the dielectric medium were examined on influencing EDM performance on Inconel 825 work material. Moreover, effects of peak discharge current on EDM responses were discussed.

     

Carboxymethylation of cellulosic material (average degree of polymerization 2600) isolated from cotton (Gossypium) linters with respect to degree of substitution and rheological behavior

Carboxymethylation of cellulosic material (average degree of polymerization 2600) containing 76.5% cellulose and 23.6% xylose isolated from cotton (Gossypium) linters was studied under varying reaction conditions with respect to maximum degree of substitution (DS). The influence of reaction conditions on the apparent viscosity of the prepared derivatives was also studied. The conditions optimized were sodium hydroxide concentration 3.75M, monochloroacetic acid concentration 2.05 mol/AGU, carboxymethylation time 3.5 h, and temperature 55°C, to yield carboxymethyl cellulose of DS 0.77. Rheological studies of 1 and 2% solutions of the optimized product revealed their non‐Newtonian pseudoplastic behavior. Repeating units of the optimized product were also determined by HPLC after complete depolymerization of the polymer. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1477–1482, 2005