Fault tolerance in wireless sensor network using hand-off and dynamic power adjustment approach

Wireless Sensor Network (WSN) is deployed to monitor physical conditions in various places such as geographical regions, agriculture lands, office buildings, industrial plants and battlefields. WSNs are prone to different types of failures due to various environmental hazards like interference and internal failures (such as battery failure, processor failure, transceiver failure, etc). In such a situation, the sensed data cannot be transmitted correctly to the data center and the very purpose of deploying WSNs is not effective. Since it is difficult to monitor the network continuously through a manual operator, the nodes in WSN need to be capable of overcoming the failures and transmit the sensed data in proper order to the data center. Sensor network should be designed such that it should be able to identify the faulty nodes, try to rectify the fault and be able to transmit the sensed data to data center under faulty condition of a network and thereby make the network fault-free and thus enhance the fault tolerant capability.In this paper, we propose a novel idea of an Active node based Fault Tolerance using Battery power and Interference model (AFTBI) in WSN to identify the faulty nodes using battery power model and interference model. Fault tolerance against low battery power is designed through hand-off mechanism where in the faulty node selects the neighboring node having highest power and transfers all the services that are to be performed by the faulty node to the selected neighboring node. Fault tolerance against interference is provided by dynamic power level adjustment mechanism by allocating the time slot to all the neighboring nodes. If a particular node wishes to transmit the sensed data, it enters active status and transmits the packet with maximum power; otherwise it enters into sleep status having minimum power that is sufficient to receive hello messages and to maintain the connectivity. The performance evaluation is tested through simulation for packet delivery ratio, control overhead, memory overhead and fault recovery delay. We compared our results with Fault Detection in Wireless Sensor Networks (FDWSNs) for various performance measures and found that AFTBI outperforms compared to the results of FDWSN.     

An algorithm for the kinetics of tire pyrolysis under different heating rates

Tires exhibit different kinetic behaviors when pyrolyzed under different heating rates. A new algorithm has been developed to investigate pyrolysis behavior of scrap tires. The algorithm includes heat and mass transfer equations to account for the different extents of thermal lag as the tire is heated at different heating rates. The algorithm uses an iterative approach to fit model equations to experimental data to obtain quantitative values of kinetic parameters. These parameters describe the pyrolysis process well, with good agreement (r² > 0.96) between the model and experimental data when the model is applied to three different brands of automobile tires heated under five different heating rates in a pure nitrogen atmosphere. The model agrees with other researchers’ results that frequencies factors increased and time constants decreased with increasing heating rates. The model also shows the change in the behavior of individual tire components when the heating rates are increased above 30 K min⁻¹. This result indicates that heating rates, rather than temperature, can significantly affect pyrolysis reactions. This algorithm is simple in structure and yet accurate in describing tire pyrolysis under a wide range of heating rates (10–50 K min⁻¹). It improves our understanding of the tire pyrolysis process by showing the relationship between the heating rate and the many components in a tire that depolymerize as parallel reactions.     

Studies on physico-mechanical properties of some new light weight engineering materials

Industrial, agricultural, and naturally occurring waste materials in conjunction with liquid epoxy resin, silica and asbestos were employed to make light weight engineering composite materials. To bring down the cost of the expensive resin, additives such as linseed oil and urea formaldehyde were added to replace the bulk of epoxy resin. Various physico-mechanical properties of these composites were studied. In comparison with ordinary cement concrete, properties such as water absorption and fire resistance improved substantially for the majority of mixes, whereas other physico-mechanical properties did not improve greatly in many cases. Such composites, which are similar to (and in some cases better than) ordinary cement concrete can be of use in building technology because of substantially lower prices.     

Complex impedance studies of low temperature synthesized fine grain PZT/CeO2 nanocomposites

Fine grain nanocomposites of (100 ? x) PbZr_0.52Ti_0.48O₃ ? (x) CeO₂ with x = 0.5, 1 and 2 wt%, were prepared and characterized for structural and microstructural changes. Addition of ceria nanoparticles resulted into a fine grain microstructure with average grain size ranging from 600 nm to 440 nm and a significant decrease in sintering temperature (～200 °C). Size distribution profile, as analyzed by lognormal distribution function suggests a very narrow size distribution. X-ray diffraction analyses of sintered samples reveal that fine grain PZT/CeO₂ nanocomposite could retain distorted tetragonal structure even with grain size as low as 440 nm. Further, complex impedance spectroscopy studies were performed to illustrate the electrical properties of bulk and grain boundary phases in fine grain ceramics. Two electrical processes in the impedance spectra at temperatures above 350 °C were attributed to bulk and grain boundary phase. Magnitude of grain boundary capacitance and corresponding transition was found to be strongly dependent on grain size of the system. Both bulk and grain boundary relaxation processes follows Arrhenius law.     

Detection and identification of genetically modified EE‐1 brinjal (Solanum melongena) by single,multiplex and SYBR® real‐time PCR

BACKGROUND: Brinjal is an important vegetable crop. Major crop loss of brinjal is due to insect attack. Insect‐resistant EE‐1 brinjal has been developed and is awaiting approval for commercial release. Consumer health concerns and implementation of international labelling legislation demand reliable analytical detection methods for genetically modified (GM) varieties. RESULTS: End‐point and real‐time polymerase chain reaction (PCR) methods were used to detect EE‐1 brinjal. In end‐point PCR, primer pairs specific to 35S CaMV promoter, NOS terminator and nptII gene common to other GM crops were used. Based on the revealed 3′ transgene integration sequence, primers specific for the event EE‐1 brinjal were designed. These primers were used for end‐point single, multiplex and SYBR‐based real‐time PCR. End‐point single PCR showed that the designed primers were highly specific to event EE‐1 with a sensitivity of 20 pg of genomic DNA, corresponding to 20 copies of haploid EE‐1 brinjal genomic DNA. The limits of detection and quantification for SYBR‐based real‐time PCR assay were 10 and 100 copies respectively. CONCLUSION: The prior development of detection methods for this important vegetable crop will facilitate compliance with any forthcoming labelling regulations. Copyright © 2012 Society of Chemical Industry     

The onset of double diffusive convection in a sparsely packed porous layer using a thermal non-equilibrium model

We examine the effect of local thermal non-equilibrium on double diffusive convection in a fluid-saturated sparsely packed porous layer heated from below and cooled from above, using both linear and nonlinear stability analyses. The Brinkman model is employed as the momentum equation. A two-field model that represents the fluid and solid phase temperature fields separately is used for the energy equation. The onset criterion for stationary, oscillatory and finite amplitude convection is derived analytically. It is found that a small inter-phase heat transfer coefficient has significant effect on the stability of the system. There is a competition between the processes of thermal and solute diffusion that causes the convection to set in through either oscillatory or finite amplitude mode rather than stationary. The effect of solute Rayleigh number, porosity modified conductivity ratio, Lewis number, ratio of diffusivities, Vadasz number and Darcy number on the stability of the system is investigated. The nonlinear theory based on the truncated representation of Fourier series method predicts the occurrence of subcritical instability in the form of finite amplitude motions. The effect of thermal non-equilibrium on heat and mass transfer is also brought out.     

Surface roughness effects on curved pivoted slider bearings with couple stress fluid

In this paper the effect of surface roughness on the performance of curved pivoted slider bearings is studied. A more general type of surface roughness is mathematically modelled by a stochastic random variable with nonzero mean, variance and skewness. The averaged modified Reynolds type equation is derived on the basis of Stokes microcontinuum theory for couple stress fluids. The closed‐form expressions for the mean pressure, load‐carrying capacity, frictional force and the centre of pressure are obtained. Numerical computations show that the performance of the slider bearing is improved by the use of lubricants with additives (couple stress fluid) as compared to Newtonian lubricants. Further, it is observed that the negatively skewed surface roughness increases the load‐carrying capacity and frictional force and reduces the coefficient of friction, whereas the positively skewed surface roughness on the bearing surface adversely affects the performance of the pivoted slider bearings. Copyright © 2006 John Wiley & Sons, Ltd.     

Assessment of DNA degradation induced by thermal and UV radiation processing: Implications for quantification of genetically modified organisms

DNA quality is an important parameter for the detection and quantification of genetically modified organisms (GMO’s) using the polymerase chain reaction (PCR). Food processing leads to degradation of DNA, which may impair GMO detection and quantification. This study evaluated the effect of various processing treatments such as heating, baking, microwaving, autoclaving and ultraviolet (UV) irradiation on the relative transgenic content of MON 810 maize using pRSETMON-02, a dual target plasmid as a model system. Amongst all the processing treatments examined, autoclaving and UV irradiation resulted in the least recovery of the transgenic (CaMV 35S promoter) and taxon-specific (zein) target DNA sequences. Although a profound impact on DNA degradation was seen during the processing, DNA could still be reliably quantified by Real-time PCR. The measured mean DNA copy number ratios of the processed samples were in agreement with the expected values. Our study confirms the premise that the final analytical value assigned to a particular sample is independent of the degree of DNA degradation since the transgenic and the taxon-specific target sequences possessing approximately similar lengths degrade in parallel. The results of our study demonstrate that food processing does not alter the relative quantification of the transgenic content provided the quantitative assays target shorter amplicons and the difference in the amplicon size between the transgenic and taxon-specific genes is minimal.