Wireless Sensor Network Path Optimization Using Sensor Node Coverage Area Calculation Approach

The proposed work is based on the path optimization approach for wireless sensor network (WSN). Path optimization is achieved by using the NSG 2.1 Tool, TCL Script file and NS2 simulator to improve the quality of service (QoS). Path optimization approach finds best suitable path between sensor nodes of WSN. The routing approach is not only the solution to improve the quality but also improves the WSN performance. The node cardinally is taken under consideration using the ad-hoc on demand distance vector routing protocol mechanism. Ad hoc approach emphasize on sensor nodes coverage area performance along with simulation time. NSG 2.1 Tool calculates the sensor node packet data delivery speed which can facilitate inter-node communication successfully. An experimental result verified that the proposed design is the best possible method which can escape from slow network response while covering maximum sensor nodes. It achieves coverage support in sensor node deployment. The result outcomes show best path for transferring packet from one sensor node to another node. The coverage area of sensor node gives the percentage of average coverage ratio of each node with respect to the simulation time.

     

Fabrication and Wear Behavior of Nanostructured Plasma-Sprayed 6061Al-SiCp Composite Coating

6061Al powder with 15 wt.% SiC particulate (SiC_p) reinforcement was mechanically alloyed (MA) in a high-energy attrition mill. The MA powder was then plasma sprayed onto weathering steel (Cor-Ten A242) substrate using an atmospheric plasma spray process. Results of particle size analysis and scanning electron microscopy show that the addition of SiC particles as the reinforcement influences on the matrix grain size and morphology. XRD studies revealed embedment of SiC_p in the MA-processed composite powder, and nanocrystals in the MA powder and the coating. Microstructural studies showed a uniform distribution of reinforced SiC particles in the coating. The porosity level in the coating was as low as 2% while the coating hardness was increased to 232VHN. The adhesion strength of the coatings was high and this was attributed to higher degree of diffusion at the interface. The wear rate in the coatings was evaluated using a pin-on-disk type tribometer and found to decrease by 50% compared to the 6061Al matrix coating. The wear mechanism in the coating was delamination and oxidative type.     

Application of a real-time predictive maintenance system to a production machine system

This paper develops earlier work that established the possibility of the classification of machine system parameters on the basis of motion current signature, using a neural network approach. A neural network requires a large amount of training data, which is impractical to generate using a production machine for real-time predictive maintenance system. Hence, a simulation model, which mapped the system parameters to the motion current signature, was developed. The accuracy of the system, to predict the changes in the value of the machine system parameter, is a direct function of the validity of the simulated data. Thus, the objective validation of the simulation model is important to ascertain that the simulation model is accurate with regards to its purpose.In this paper, the simulation model is validated against an on-line production machine. Various approaches to validate the simulation model are applied and a simulation model is developed.     

A study on thermal behavior of a poly(VDF‐CTFE) copolymers binder for high energy materials

This article describes a study on thermal behavior of poly(vinylidene fluoride‐chlorotrifluoroetheylene) [poly(VDF‐CTFE)] copolymers as polymeric binders of specific interest for high energy materials (HEMs) composites by thermal analytical techniques. The non‐isothermal thermogravimetry (TG) for poly (VDF‐CTFE) copolymers was recorded in air and N₂ atmospheres. The results of TG thermograms show that poly(VDF‐CTFE) copolymers get degrade at lower temperature when in air than in N₂ atmosphere. In the derivative curve, there was single maximum degradation peak (T_max) indicating one‐stage degradation of poly(VDF‐CTFE) copolymers for all the samples. The other thermal properties such as glass transition temperature (T_g) and degradation temperature (T_d) for poly(VDF‐CTFE) copolymers were measured by employing differential scanning calorimeter (DSC) technique. The kinetic parameters related to thermal degradation of poly(VDF‐CTFE) copolymers were investigated through non‐isothermal Kissinger kinetic method using DSC method. The activation energies for thermal degradation of poly(VDF‐CTFE) copolymers were found in a range of 218–278 kJ/mol. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Carboxymethylation of Cassia tora gum

The preparation of carboxymethyl (CM)–Cassia tora gum (CTG) with monochloroacetic acid and sodium hydroxide was investigated under different reaction conditions. The carboxymethylation reaction was studied with respect to the degree of substitution of CM–CTG. The variables studied were the concentration of reactants, methanol–water ratio (solvent), reaction time, and reaction temperature. Carboxymethylation of CTG increased its solubility in cold water and the stability of its paste to microorganisms. Regardless of the degree of substitution of these products, their aqueous solutions were characterized by non‐Newtonian pseudoplastic behavior. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3216–3219, 2003     

In situ entrapment of α‐chymotrypsin in the network of acrylamide and 2‐hydroxyethyl methacrylate copolymers

A mild and reproducible method has been developed for the entrapment of α‐chymotrypsin into a crosslinked copolymer. A porous copolymer was synthesized at 293 K by solution copolymerization of acrylamide and 2‐hydroxyethyl methacrylate. α‐Chymotrypsin was entrapped during copolymerization at different polymerization stages. The effect of crosslinking on enzyme loading and retention of its activity was examined. Copolymer with 2% crosslinking could entrap >90% of the enzyme. The activity of free and immobilized α‐chymotrypsin was determined by using N‐benzoyl‐L ‐tyrosine ethyl ester and casein as low and high molecular weight substrates respectively. Storage as well as thermal stability of the immobilized enzyme was superior to that of the free one. Effect of calcium and heavy metal ions was studied on immobilized enzyme activity. The immobilized enzyme showed little variation in activity with pH and retained 50% activity after nine cycles. The Michaelis constant K_m of the free and immobilized enzyme was estimated to be 2.7 and 4.2 × 10⁻³ mM, respectively, indicating no conformational changes during entrapment. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2996–3002, 2000     

Optical properties of nano-silicon

We investigated the optical properties of silicon clusters and Si nanocrystallites using photolumine-scence (PL) and Raman scattering technique. Broad luminescence band in the red region was observed from Si-doped SiO₂ thin films deposited by co-sputtering of Si and SiO₂ onp-type Si (100) substrates, annealed in Ar and O₂ atmosphere. Nanocrystalline Si particles fabricated by pulsed plasma processing technique showed infrared luminescence from as grown film at room temperature. Raman spectra from these films consisted of broad band superimposed on a sharp line near 516 cm⁻¹ whose intensity, frequency, and width depend on the particle sizes arising from the phonon confinement in the nanocrystalline silicon. We also performed PL, Raman and resonantly excited PL measurements on porous silicon film to compare the optical properties of Si nanostructures grown by different techniques. An extensive computer simulation using empirical pseudo-potential method was carried out for 5–18 atoms Si clusters and the calculated gap energies were close to our PL data. Paper presented at the 5th IUMRS ICA98, October 1998, Bangalore.     

Finite element crash simulations of the human body: Passive and active muscle modelling

Conventional dummy based testing procedures suffer from known limitations. This report addresses issues in finite element human body models in evaluating pedestrian and occupant crash safety measures. A review of material properties of soft tissues and characterization methods show a scarcity of material properties for characterizing soft tissues in dynamic loading. Experiments imparting impacts to tissues and subsequent inverse finite element mapping to extract material properties are described. The effect of muscle activation due to voluntary and non-voluntary reflexes on injuries has been investigated through finite element modelling.     

Effects of anisotropy and annealing on microhardness of In x Bi2−x Te3 (x=0·1 to 0·5) single crystals

The crystals of In _x Bi_2−x Te₃ (x=0·1 to 0·5) have been grown by zone-melting method. In order to study anisotropy exhibited by the (0001) plane of the crystals, the directional hardness was determined by producing indentations at various azimuthal orientations of the indentor with respect to the surface over a range 0–180°. The crystal was rotated about the indentor axis in steps of 15° while keeping applied load and loading time constant at 50 g and 20 sec, respectively. For annealing study, the sample was kept at a temperature of 375°C. It was observed that softening of crystal takes place and the hardness decreases to a considerable extent.