Magnetic measurements,Raman and infrared spectra of metal–ligand complex derived from $$\hbox {CoCl}_{2}\cdot \hbox {6H}_{2}\hbox {O}$$ and 2-benzoyl pyridine

Nanocrystalline complex of \(\hbox {CoCl}_{2}\cdot 6\hbox {H}_{2}\hbox {O}{-}2\)-benzoyl pyridine is prepared by chemical route. Each component of the desired complex is identified by analysing the X-ray diffractograms. Energy-dispersive X-ray analysis (EDX) data confirmed the presence of the desired elements of the sample. Theoretical optimized structure of the complex was derived using ab initio density functional level of theory (DFT) method of calculation. The average nanocrystallite size estimated from the XRD data is \(\sim \)43 nm. Static magnetic property of the complex is studied in the temperature range from 300 K down to 14 K. The estimated magnetic moment of the complex is high when compared to that of the free ion magnetic moment of \(\hbox {Co}^{2+}\) and this is attributed to the less effect of the crystal field acting on the ion in the organic complex due to which orbital moments are not fully quenched. The magnetic property of the complex is also remarkably enhanced compared to that of the diamagnetic 2-benzoyl pyridine which may be suitable for applications in devices. FTIR and Raman spectra of the ligand, 2-benzoyl pyridine and the synthesized complex are recorded at room temperature, which not only confirm the presence of each phase in the complex, but some interesting results are also extracted from the analyses of different Raman active modes of the complex.     

Surface morphology and composition of films grown by size-selected Cu nanoclusters

We report the investigation of morphology and composition of copper nanocluster films deposited on Si substrates. The nanoclusters are formed in an aggregation tube at room temperature and magnetron sputtering source is used to get negatively charged Cu-clusters' beam which is subsequently mass-filtered to get size-selected cluster on the substrates as soft-landing process of deposition. For composition of the films, X-ray photoelectron spectroscopy (XPS) technique is used. For morphological changes of the films both scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses are carried out. Additionally, Energy Dispersive X-ray (EDX) spectra support the compositional and structural informations of the film. The analysis of Cu nanoclusters' films reveals that initial nucleation of Cu clusters takes place in the form of isolated islands and the arrival of subsequent Cu clusters onto Si substrates has preferential aggregation around the preceding clusters forming a mound structure.     

Stochastic response of articulated leg platform in probability domain

The probability density function (PDF) of the nonlinear response of an articulated leg platform (ALP) is obtained using stochastic averaging procedure together with weighted residual error minimization technique. Since stochastic averaging procedure is strictly applicable for weak (small size) excitations and damping functions, the error minimization technique has been employed to take into account the size effect which arises in practical problems like ALP. The application of the method to articulated leg platform also requires relative velocity squared drag force to be expressed in a manner which allows stochastic averaging procedure to be used. The procedure uses random Van-der-Pol transformation, FPK equation and Itoˆs equation of limiting diffusion process assuming the response to be slowly converging to diffusive Markov process. The computation scheme is developed using FFT to obtain the averaged drift and diffusion coefficients of the Itoˆs equation. An articulated tower with variable buoyancy chamber in a water depth of 141 m is analyzed for a random sea state represented by the Pierson–Morkowitz (P–M) spectrum having 16 and 8 m significant wave heights. The tower is idealized as a SDOF system with the rotation (φ) of the tower at the base hinge as unknown. The PDF of the angular rotation (φ) and the joint PDF are obtained and compared with those derived from the simulation analysis. A 20 min sea state corresponding to the P–M spectrum is simulated for this purpose. It is shown that the procedure provides results which compare very well with those obtained from the simulation analysis     

Development of autonomous mobile robot with manipulator for manufacturing environment

This paper describes the developmental effort involved in prototyping the first indigenous autonomous mobile robot, AMR, with a manipulator for carrying out tasks related to manufacturing. The objective is to design and develop a vehicle that can navigate autonomously and transport jobs and tools in a manufacturing environment. Proprioceptive and exteroceptive sensors are mounted on AMR for navigation. Among the exteroceptive sensors, a stereovision camera is mounted in front of AMR for mobile robot perception of the environment. Using the widely supported JPEG image file format, full high-resolution color images are transmitted frame by frame from the mobile robot to multiple viewers located within the robot work area, where fast reconstruction of these images enables remote viewing. A CMOS camera mounted on the manipulator identifies jobs for pick-and-place operation. A variation of correlation based adaptive predictive search (CAPS) method, a fast search algorithm in template matching, is used for job identification. The CAPS method justifiably selects a set of search steps rather than consecutive point-to-point search for faster job identification. Search steps, i.e., either coarse search or fine search, are selected by calculating the correlation coefficient between template and the image. Adaptive thresholding is used for image segmentation for parametric calculations required for proper gripping of the object. Communication with the external world allowing remote operation is maintained through wireless connectivity. It is shown that autonomous navigation requires synchronization of different processes in a distributed architecture, while concurrently maintaining the integrity of the network.     

Development of nano-structured Al2O3-TiB2-TiN coatings by combined SHS and laser surface alloying

A powder mixture of aluminium (Al), titania (TiO₂) and hexa-boron nitride (h-BN) was laser-triggered to undergo SHS (self-propagating high temperature synthesis) and was subsequently laser alloyed onto a mild steel substrate surface. A nano-structured coating was formed with high microhardness (～3000 HV_0.05 at the cross-section and ～2600 HV_0.2 on the top surface). X-ray diffraction (XRD) identified the presence of aluminium oxide (Al₂O₃), titanium di-boride (TiB₂), titanium nitride (TiN), iron (Fe) and its borides (FeB, Fe₂B) in the coating. Scanning electron microscopy (SEM) and high resolution transmission electron microscopic (HRTEM) analysis of the coating revealed nano-fibrous titanium-rich reinforcements in a matrix of nano-crystalline alumina. The thickness of titanium di-boride nano-fibres was an order of magnitude higher than the size of nano-alumina crystallites.     

Slag recycling in submerged arc welding and its influence on weld quality leading to parametric optimization

Slag generated during conventional submerged arc welding (SAW) has been recycled by mixing varying percentages of crushed slag with fresh flux to use in subsequent runs. The influence of using flux-slag mixture on various aspects of SAW weld parameters of bead geometry have been investigated in a quantitative basis. Slag has been reprocessed and reused in submerged arc welding to produce bead-on-plate weld on mild steel plates. Apart from conventional process parameters: voltage (OCV), wire feed rate, nozzle to plate distance (stick-out) and traverse speed, welding has been carried out using various percentages of flux-slag mixture; the % of fused flux in the mixture has been treated as a process parameter. Various bead geometry parameters viz. bead width; reinforcement, depth of penetration and depth of HAZ have been measured for each of weld prepared in the study. Using experimental data, a grey-based Taguchi approach has been applied for parametric optimization of this non-conventional SAW process. The aim was to reveal the optimal amount of slag-mix%, which could be applied in SAW process without imposing any adverse effect on features of bead geometry and HAZ. Optimal result has been checked through confirmatory test.     

Solving multi-criteria optimization problem in submerged arc welding consuming a mixture of fresh flux and fused slag

In the present work, application of the Taguchi method in combination with grey relational analysis has been applied for solving multiple criteria (objective) optimization problem in submerged arc welding (SAW). A grey relational grade evaluated with grey relational analysis has been adopted to reveal an optimal parameter combination in order to obtain acceptable features of weld quality characteristics in submerged arc bead-on-plate welding. The idea of slag utilization, in subsequent runs, after mixing it with fresh unmelted flux, has been introduced. The parentage of slag in the mixture of fresh flux and fused flux (slag) has been denoted as slag-mix%. Apart from two conventional process parameters: welding current and flux basicity index, the study aimed at using varying percentages of slag-mix, treated as another process variable, to show the extent of acceptability of using slag-mix in conventional SAW processes, without sacrificing any characteristic features of weld bead geometry and HAZ, within the experimental domain. The quality characteristics associated with bead geometry and HAZ were bead width, reinforcement, depth of penetration and HAZ width. Using grey relational grade as performance index, we have performed parametric optimization yielding the desired features of bead geometry and HAZ. Predicted results have been verified with confirmatory experiments, showing good agreement. This proves the utility of the proposed method for quality improvement in SAW process and provides the maximum (optimum) amount of slag-mix that can be consumed in the SAW process without any negative effect on characteristic features of the quality of the weldment in terms of bead geometry.     

Thermal stresses during freezing of a two-layer food

Thermal stresses during freezing of a two-layer material, that can contribute to crack formation, are studied. A 3D numerical model of a two-layer food with food analog Tylose^® and chocolate is presented. An apparent specific heat formulation was used to model the heat transfer with phase change over a temperature range. The mechanics model considered viscoelasticity in Tylose^®; thermal strains were imposed due to the increase in volume from ice formation in Tylose^® and the decrease in volume from freezing of the chocolate. Results show that complex evolution of stresses, that include compressive and tensile values, occur during freezing. Sensitivity analysis showed that the Poisson's ratio was a very important parameter that affects the magnitude of stress. Variations in calculated stresses were found to be proportional to variations in Young's modulus. Knowing the stresses, the possibilities of undesired cracking of a chocolate coating applied onto another material such as ice cream could be evaluated.     

Functionalized carbon nanotubes for detecting viral proteins

We investigated the biocompatibility, specificity, and activity of a ligand-receptor-protein system covalently bound to oxidized single-walled carbon nanotubes (SWNTs) as a model proof-of-concept for employing such SWNTs as biosensors. SWNTs were functionalized under ambient conditions with either the Knob protein domain from adenovirus serotype 12 (Ad 12 Knob) or its human cellular receptor, the CAR protein, via diimide-activated amidation. We confirmed the biological activity of Knob protein immobilized on the nanotube surfaces by using its labeled conjugate antibody and evaluated the activity and specificity of bound CAR on SWNTs, first, in the presence of fluorescently labeled Knob, which interacts specifically with CAR, and second, with a negative control protein, YieF, which is not recognized by biologically active CAR proteins. In addition, current-gate voltage (I-V(g)) measurements on a dozen nanotube devices explored the effect of protein binding on the intrinsic electronic properties of the SWNTs, and also demonstrated the devices' high sensitivity in detecting protein activity. All data showed that both Knob and CAR immobilized on SWNT surfaces fully retained their biological activities, suggesting that SWNT-CAR complexes can serve as biosensors for detecting environmental adenoviruses.