Pervasive Personal Computing in an Internet Suspend/Resume System

The Internet suspend/resume model of mobile computing cuts the tight binding between PC state and PC hardware. By layering a virtual machine on distributed storage, ISR lets the VM encapsulate execution and user customization state; distributed storage then transports that state across space and time. This article explores the implications of ISR for an infrastructure-based approach to mobile computing. It reports on experiences with three versions of ISR and describes work in progress toward the OpenISR version     

TARA: Topology-Aware Resource Adaptation to Alleviate Congestion in Sensor Networks

Network congestion can be alleviated either by reducing demand (traffic control) or by increasing capacity (resource control). Unlike in traditional wired or other wireless counterparts, sensor network deployments provide elastic resource availability for satisfying the fidelity level required by applications. In many cases, using traffic control can violate fidelity requirements. Hence, we propose the use of resource control: increasing capacity by enabling more nodes to become active during periods of congestion. However, a naive approach to increase resources without a careful consideration of the type of congestion, traffic pattern, and network topology make the situation worse. In this paper, we present TARA, a topology-aware resource adaptation strategy to alleviate congestion. The core of TARA is our capacity analysis model, which can be used to estimate capacity of various topologies. Detailed performance results show that TARA can achieve data delivery rate and energy consumption that is close to an ideal offline resource control algorithm.     

Superconducting State Parameters of 5d-Transition Metals Based Binary Alloys

The theoretical study of the superconducting state parameters (SSP) viz. electron–phonon coupling strength λ, Coulomb pseudopotential μ ^*, transition temperature T _C , isotope effect exponent α and effective interaction strength N _O V of 5d-transition metals based binary alloys have been made extensively in the present work using a model potential for the first time. A considerable influence of various exchange and correlation functions on λ and μ ^* is found from the present study. The present results of the SSP are found in qualitative agreement with the available experimental data wherever it exists.     

On simultaneous on-line state and parameter estimation in non-linear state-space models

On-line estimation plays an important role in process control and monitoring. Obtaining a theoretical solution to the simultaneous state-parameter estimation problem for non-linear stochastic systems involves solving complex multi-dimensional integrals that are not amenable to analytical solution. While basic sequential Monte-Carlo (SMC) or particle filtering (PF) algorithms for simultaneous estimation exist, it is well recognized that there is a need for making these on-line algorithms non-degenerate, fast and applicable to processes with missing measurements. To overcome the deficiencies in traditional algorithms, this work proposes a Bayesian approach to on-line state and parameter estimation. Its extension to handle missing data in real-time is also provided. The simultaneous estimation is performed by filtering an extended vector of states and parameters using an adaptive sequential-importance-resampling (SIR) filter with a kernel density estimation method. The approach uses an on-line optimization algorithm based on Kullback–Leibler (KL) divergence to allow adaptation of the SIR filter for combined state-parameter estimation. An optimal tuning rule to control the width of the kernel and the variance of the artificial noise added to the parameters is also proposed. The approach is illustrated through numerical examples.     

Above ground standing biomass and carbon storage in village bamboos in North East India

Bamboo forms an important component in the traditional landscape of North East India. For biomass estimation of village bamboos of Barak Valley, North East India, allometric relationships were developed by harvest method describing leaf, branch and culm biomass with DBH as an independent variable using a log linear model. The culm density of the stand was 8950 culms ha⁻¹ during 2005 of which 67% of growing stock was represented by Bambusa cacharensis, 17.88% by Bambusa vulgaris and 15.12% by Bambusa balcooa. Above ground stand biomass was 121.51 t ha⁻¹ of which 86% was contributed by culm component followed by branch (10%) and leaf (4%). With respect to species, B. cacharensis made up to 46% of total stand biomass followed by B. vulgaris (28%) and B. balcooa (26%). Carbon storage in the above ground biomass was 61.05 t ha⁻¹. Allocation of C was more in culm components (53.05 t ha⁻¹) than in branch (5.81 t ha⁻¹) and leaf (2.19 t ha⁻¹). Carbon storage in the litter floor mass was 2.40 t ha⁻¹, of which leaf litter made up the highest amount (1.37 t ha⁻¹) followed by sheath (0.86 t ha⁻¹) and branch (0.17 t ha⁻¹). Carbon stock in the soil up to 30 cm depth was 57.3 t ha⁻¹. Gross C stock in the plantation was estimated to be 120.75 t ha⁻¹. Carbon storage estimated in the bamboo stand of present study offers insights into the opportunity of village bamboos in the rural landscape for carbon storage through carbon sequestration. Management and utilization of village bamboos as a potential source of carbon sink by smallholder farmers are discussed in the context of their livelihood security and the Millennium Development Goals of the United Nations.     

An electronically tunable microstrip bandpass filter using thin-film Barium-Strontium-Titanate (BST) varactors

A tunable third-order combline bandpass filter using thin-film barium-strontium-titanate varactors and fabricated on a sapphire substrate is reported. Application of 0-200-V bias varied the center frequency of the filter from 2.44 to 2.88 GHz (16% tuning) while achieving a 1-dB bandwidth of 400 MHz. The insertion loss varied from 5.1 dB at zero bias to 3.3 dB at full bias, while the return loss exceeded 13 dB over the range. The third-order intercept of the filter was found to be 41 dBm.     

Evaluation of Thermocyclic Oxidation Behavior of HVOF-Sprayed NiCrFeSiB Coatings on Boiler Tube Steels

High velocity oxy-fuel (HVOF) spray process has grown into a well-accepted industrial technology for obtaining coatings resistant to significant surface degradation processes. In the present study, HVOF process was used to deposit Ni-based hardfacing NiCrFeSiB alloy powder on kinds of boiler tube steels designated as SA210 grade-A1, SA213-T11, and SA213-T22. The microstructures and several properties of the as-sprayed coatings have been investigated. Thermocyclic oxidation studies were performed in static air at 900 °C. NiCrFeSiB-coated steels showed slow oxidation kinetics and considerably lower weight gains than that of uncoated steels. The superior performance of NiCrFeSiB coatings can be attributed to continuous and protective thin oxide scale of amorphous SiO₂ and Cr₂O₃ formed on the surface of the oxidized coatings. The combined technique of x-ray diffraction, scanning electron microscopy, energy dispersive x-ray analysis, and electron probe microanalysis are used to characterize reaction products of the oxidized surfaces.