Analysis of surface reproduction characteristics of different replica materials

Film type replica materials were assessed regarding their suitability for the reproduction of surface characteristics. A detailed statistical analysis of the digitized profile of the original surface and that of replicas made from different materials was made and the results are discussed.     

Effect of SiC particle size and content on strain-based pore closure rate studies on Al–SiC P/M composites during cold upsetting

A series of laboratory-scale powder metallurgical upsetting experiments was conducted during cold upsetting on sintered Al–SiC composites. Aluminium–silicon carbide composites containing 5%, 10%, 15% and 20% SiC of four different particle sizes, namely 50, 65, 120 and 180 μm, were completely investigated. The pore closing rate and the formability strain index value were evaluated and discussed in terms of matrix and geometric work hardenings. Three novel strain-based pore closure rate indices were proposed and analysed for all the above said preforms, and their variations with respect to their relative density were plotted and discussed.     

Preparation,characterization and effect of calcium carbonate and titanium dioxide nano additives on fuel properties of tire oil diesel blend

The present study deals with the preparation, characterization, and effect of and Calcium carbonate (CaCO₃) and Titanium dioxide (TiO₂) Nano additives on the fuel properties in the tire oil–diesel fuel blend. The above said Nanoparticles were prepared by the ball milling method using toluene as the solvent. Tire oil was prepared from scrap tires by pyrolysis process in the temperature range of 400–650°C. The morphology and particle size were determined by means of Scanning Electron Microscope (SEM). From the SEM image, the particle size for CaCO₃ and TiO₂ was found to be 153nm and 99.2nm, respectively, which strongly confirms the particles size in Nano range. Fourier Transform Infrared (FTIR) Spectroscopy was used to study the chemical compounds in the Nanoparticles. The presence of peaks in the wavelength range of 700–500 cm^?1 validates the presence of metallic compounds in the particles. The crystal structure of the Nanoparticles was determined by X-Ray Diffraction (XRD) technique and the Nano crystallite structure was calculated by using Debye-Scherer equation. The diffraction peaks obtained from the XRD patterns were indexed to the pure cubic fluorite structure of CaCO₃ and TiO₂. From the Debye Scherer’s equation the particle size for CaCO₃ and TiO₂ were found to be 24.48nm and 37.86 nm, respectively. Visualisation of the Nanoparticles in three dimensions was carried out by Atomic Force Microscopy (AFM) from which the maximum and minimum size of the particles was determined. The maximum and minimum particle sizes were found to be 99nm and 62nm for CaCO₃ whereas for TiO₂ it is found to be 76nm and 47nm, respectively. Particle size analyzer was used to calculate the average size of the particle. 1000 ppm of the prepared Nanoparticles was added to tire oil-diesel fuel blend (T20) by means of probe sonication and the phase stability of the blends with CaCO₃ and TiO₂ Nanoparticles were found to be ?18.1 mV and ?26.2 mV, respectively. The fuel properties such as viscosity, density, calorific value, flash point, cetane number, cloud point, and pour point were found to align with that of ASTM standards and can be considered as an alternate energy source in a Compression Ignition engine.     

Development of bandwidth-enhanced X–Ku band reflectarray antenna using a novel design strategy

This paper reports the development of a reflectarray (RA) antenna using overlapping tri-resonance phase distribution to produce enhanced bandwidth performance in X/Ku band frequencies. The RA with square aperture (24 cm) operating from 11 to 15.8 GHz is constructed using unit cells with concentric Malta cross and square ring developed on Diclad substrate isolated from the ground through a 2.5-mm air layer. Variation in the concentric element's size along with the length of the delay line connected to the square ring offers a 518° phase range. The distribution of the 529 RA elements is done using the phase variations observed at 12, 13, and 14 GHz. The optimized design of the proposed antenna offers a simulated peak gain of 27.43 dBi at 12 GHz and a 1-dB gain bandwidth of 38%. The experimental validation of the fabricated prototype exhibits a peak gain of 27.4 dBi at 12 GHz with a sidelobe level (SLL), and cross-polarization level less than −15.6 dB, and −28 dB respectively, and a 1-dB gain bandwidth of 37%. The enhanced performance characteristics of the proposed X/Ku wideband reflectarray antenna befit the uplink and downlink operations of fixed satellite services (FSS).     

A Cluster-Based Quad-Tree Partitioning for Scheduling the Mobile Element in Wireless Sensor Networks

In Wireless Sensor Networks, collection of data from the sensor nodes without data loss is a major challenge of great concern. Nodes are deployed statically and will relay the data to the base station which lead to the problem of energy-drain to the nodes near the base station since these nodes have to constantly relay data to the base station. Data collection from the sensor nodes by the mobile node or element without data loss is termed as the scheduling of the Mobile Element (ME). The proposed problem can be classified into three phases. In the initial phase, the nodes are clustered according to their geographical region in a hierarchical fashion. In the second phase, the nodes within each cluster which are in the active state are only visited by the mobile element. Quad-tree based partitioning is performed in order to schedule the visit by ME to the nodes in the active state within each cluster. In the third phase, the ME visits only the boundary-near nodes and the speed of the ME is varied based on the simplex method such that the data loss is minimized.     

Effect of various stress ratio parameters on cold upset forging of irregular shaped billets using graphite as lubricant under plane and triaxial stress state conditions

This paper examines the effect of various stress ratio parameters on cold upset forging of commercially pure aluminium solid billets of irregular shaped billets, using graphite mixed with oil as lubricant applied on both sides under plane and triaxial stress state conditions. Billets with three different aspect ratios (ratio of height to diameter) namely, 0.5, 0.75 and 1.0, with different ‘b/a’ ratios (ratio of minor to major diameter) namely, 0.6 and 0.7 were prepared and cold forged. Cold deformation on samples were subjected to an incremental deformation steps of 3 metric tones load and at the end of each step, dimensions such as height, contact and bulged diameters being measured. The calculations were made with the assumption that the radius of curvature of the barrel followed the form of a circular arc. Analysis of the experimental data showed that there exist a relationship between the measured barrel radius and various stress ratio parameters namely, (σ_θ/σ_z), (σ_m/σ_z), (σ_eff/σ_z) and (σ_m/σ_eff) developed under plane and triaxial stress conditions. An attempt has also been made to relate the percentage height reduction with respect to the stress ratio parameters namely, (σ_θ/σ_z), (σ_m/σ_z), (σ_eff/σ_z) and (σ_m/σ_eff) developed under plane and triaxial stress conditions and found to have an increasing trend and a straight line trend with enhanced level of deformation irrespective of aspect ratios and b/a ratios tested or selected.     

Surface replication studies of small bores

Replication is one of the best methods available for studying the surface characteristics of small bores of diameter 3 mm or less. This paper deals with the detailed statistical analysis of the digitised profile of the original surface and its film replicas. Analysis shows that this method can be successfully used for the assessment of small bores of medium coarse surfaces     

Strain Limit of Extra Galvannealed InterstitialFree and Bake Hardened Steel Sheets Under Different Stress Conditions

The formability of bake hardened steel （thickness 0.82 mm）, and the extra galvannealed IF steel （thickness 0.82 mm） have been studied. The suitability of the above steels for forming applications has been critically examined. The microstructure, tensile properties, and formability parameters of the above sheet metals were determined. The manufacturing process of the steels and the significance with reference to its formability were studied.     

Thermomagnetic studies of (Co0.93Fe0.07)75−x Cr x Si15B10 metglas

Thermomagnetization measurements have been carried out on the Co-Fe-Cr-Si-B metglas up to 7.5 at% Cr. For the Co₇₀Fe₅Si₁₅Si₁₀ metglas, application of magnetic field has been found to influence the process of crystallization. Thermal annealing of this alloy at temperaturesT _c<T _a<T _cr leads to a decrease in the value ofT _c due to chemical short-range ordering (CSRO) and topological short-range ordering (TSRO). Introduction of chromium into the above alloy reduces the saturation magnetization and Curie temperature of the alloy at the rate of 5.55 emu gm^–1 and 41 K per at% Cr, respectively. These are explained due to the antiparallel coupling of the 3 d electrons of iron and cobalt atoms with those of chromium and to a deterioration in the strength of ferromagnetic exchange interactions between Co-Co, Co-Fe and Fe-Fe magnetic pairs.