Synthesis,Characterization, Solution Behavior,and Density Functional Theory Analysis of Some Pyridinium‐Based Ionic Liquids

Some picolinium ionic liquids (IL) [α/γ‐PicC _n][Br/NO₃] (n = 3, 5, 7) were synthesized and characterized by ¹H NMR data. The surface tension and density of all the IL were determined. The aggregation behavior of these IL in aqueous medium and in dichloromethane was assessed from the variation of electrical conductivity in these media. The critical aggregation concentrations of these IL in aqueous medium were found to decrease significantly by the addition of cetyltrimethylammonium bromide. The structural features and the conformation of these IL were further investigated by using density functional theory calculations. The bromide ion was found to be inclined asymmetrically to one side of the pyridinium nucleus, while the nitrogen of the nitrate group lies close to the nitronium ion of the pyridinium nucleus.     

Model of inertial spreading and imbibition of a liquid drop on a capillary plate

We outline a low‐order Lagrangian model for the inertial dynamics of spreading and imbibition of a spherical liquid cap on a plane featuring independent cylindrical capillaries without gravity. The analysis predicts the relative roles of radial and axial kinetic energy, reveals the critical Laplace number beyond which the drop oscillates, and attributes the exponent of the initial power‐law for contact patch radius vs. time to the form of capillary potential energy just after the liquid sphere touches the plate. © 2017 American Institute of Chemical Engineers AIChE J, 63: 5474–5481, 2017     

Effect of Volume Fraction of Primary Alpha Phase on Solid Particle Erosion Behavior of Ti-6Al-4V Alloy

The present article evaluates the influence of independent control factors such as percentage of primary alpha phase, impact velocity, impingement angle, and erodent size on solid particle erosion behavior of Ti-6Al-4V alloy using a statistical approach. Microstructural variation in terms of different percentage of primary alpha phase of investigated alloy has been introduced by solution annealing it at different temperatures followed by thermal aging. Solid particle erosion tests have been carried out using a sand blast–type test rig following an experimental schedule based on Taguchi's orthogonal arrays. It is observed that erosion rate and the value of percentage elongation decreased with an increase in the content of primary alpha phase from 10 to 20% and then increased for the value corresponding to the content of 30% primary alpha phase in this alloy. We observed that the solid particle erosion behavior of the investigated alloy consisting of various percentages of primary alpha phase is related to their ductility. Among all four control factors, impact velocity of the erodent has been found to be the most significant control factor influencing the solid particle erosion behavior of this alloy followed by impingement angle, percentage of primary alpha phase, and erodent size. Impact velocity has greatest static influence of 91.35%, impingement angle has an influence of 4.69%, percentage of primary alpha phase has an influence of 2.28%, and erodent size has an influence of 0.42% on solid particle erosion having R² = 0.99. Material loss during solid particle erosion of this alloy was found to be ductile in nature. Ploughing or pile-up leading to platelet formation is the primary mechanism of material loss during erosion of the alloy.     

An Efficient Channel Allocation Technique for Multiple Videos-on-Demand

There are several broadcasting protocols for video-on-demand (VOD). Most of these protocols are tailored to handle the distribution of single video for a specific range of request arrival rates. In order to distribute multiple videos, broadcasting protocols like fast broadcasting (FB), new pagoda broadcasting (NPB) and universal distribution (UD) require more channels that are proportional to the number of hot videos to be broadcast. We present here an efficient broadcasting protocol in which, channel numbers can be reduced when multiple videos are broadcast either simultaneously or asynchronously. During the low to moderate request rates, our protocol performs best as similar to other reactive protocols and saves bandwidth and requires lesser number of channels as compared to other proactive or reactive protocols.     

Ferroelectric, dielectric and piezoelectric properties of Pb1?xCex(Zr0.60Ti0.40)O3, 0?≤?x?≤?0.08

The ferroelectric, dielectric and piezoelectric properties of compositions Pb_1−x Ce _x (Zr_0.60Ti_0.40)O₃, (x = 0.0, 0.01, 0.02, 0.04, 0.06 and 0.08) are studied. The above compositions are prepared from their constituent oxides, calcined at 900 °C for 4 h and various phases present are characterized by X-ray diffraction (XRD) technique. The above powders are uniaxially pressed into circular compacts, sintered at 1,250 °C for 2 h, electroded, poled at 2 kV/mm D.C. voltage and their electrical properties are measured. The XRD analysis shows the presence of rhombohedral phase up to 2 mol% ceria while tetragonal phase found at higher concentrations. It is observed that the ferroelectric, dielectric and piezoelectric properties increase with the addition of ceria with a maximum at 2 mol% and then decreases. The higher piezo properties associated with low ceria concentration are attributed to rhombohedral phase.     

Volume Conservation Controversy of the Variable Parameter Muskingum–Cunge Method

The study analyzes the volume conservation problem of the variable parameter Muskingum–Cunge (VPMC) method for which some remedial solutions have been advocated in recent literature. The limitation of the VPMC method to conserve volume is brought out by conducting a total of 6,400 routing experiments. These experiments consist of routing a set of given hypothetical discharge hydrographs for a specified reach length in uniform rectangular and trapezoidal channels using the VPMC method, and comparing the routed solutions with the corresponding benchmark solutions obtained using the full Saint-Venant equations. The study consisted of 3,200 routing experiments carried out each in uniform rectangular and trapezoidal channel reaches. Each experiment was characterized by a unique set of channel bed slope, Manning’s roughness coefficient, peak discharge, inflow hydrograph shape factor, and time to peak. A parallel study was carried out using an alternate physically based variable parameter Muskingum discharge hydrograph (VPMD) routing method proposed by Perumal in 1994 under the same routing conditions, and the ability of both the VPMC and VPMD methods to reproduce the benchmark solutions was studied. It is brought out that within its applicability limits, the VPMD method is able to conserve mass more accurately than the VPMC method. The reason for the better performance of the former over the latter method is attributed to the physical basis of its development. It is argued that adoption of artificial remedial measures to overcome the volume conservation problem makes the VPMC method semiempirical in nature, thereby losing the fully physically based characteristics of the method. The paper also dwells on the problems of negative initial outflow or dip in the beginning of the Muskingum solution, and the negative value of the Muskingum weighting parameter. Besides, the effect of incorporating the inertial terms in the estimation of Muskingum parameters and their impact on the overall Muskingum routing solutions is addressed by conducting another set of 6,400 numerical experiments using both the VPMC and VPMD methods.     

Ultrasonic and viscometric investigations of a poly(vinyl alcohol)–dextran mixture in aqueous solution

Ultrasonic spectroscopy provided a powerful, efficient, and reliable tool for a number of investigations, including those of polymer solution dynamics, molecular interaction, and the miscibility and compatibility of biopolymers in aqueous solutions. Ultrasonic velocity and related acoustic parameters were measured as a function of the concentration of poly(vinyl alcohol) (PVA), dextran, and a PVA–dextran mixture in water with the resonance method at a frequency of 3 MHz over a temperature range of 20–50°C. From the comparative results of sound velocity, density, adiabatic compressibility, acoustic impedance, and viscosity relaxation time as a function of temperature and concentration, the mode of interaction and the compatibility and miscibility between the two biologically active macromolecules were probed and were considerable at all concentrations and temperatures because of crosslinking via hydrogen bonding involving the hydroxyl groups of both of the biomacromolecules. The interpretations of the acoustic results were confirmed by the intrinsic viscosities of the ternary systems. The significant interaction and compatibility of these biopolymers should lead to the development of pharmaceutically active molecules. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3196–3201, 2003     

Synthesis and biodegradability of starch-g-ethyl methacrylate/sodium acrylate/sodium silicate superabsorbing composite

A new superabsorbent composite polymer (SAP) has been prepared by graft copolymerization reaction using starch, ethyl methacrylate (EMA), benzoyl peroxide (BPO) as initiator and sodium acrylate as crosslinking agent. Further, it is observed that the composite doped with sodium silicate exhibits higher waterabsorbency as the silicate can well disperse in the water and enter into the network structure of the composite, thereby increasing the porosity of the composite. Sodium acrylate plays an important role as the crosslinker forming a network structure of the superabsorbent composite. The composite was characterized by IR, TGA, and XRD methods. The biodegradability of these valuable novel materials was evaluated for their industrial and commercial importance. The surface morphology was compared by scanning electron microscopy (SEM) before and after biodegradation of the composite.     

Evaluation on Effectiveness of CVD and PVD Coated Tools during Dry Machining of Incoloy 825

With wide applications of nickel-based superalloys in strategic fields, it has become increasingly necessary to evaluate the performance of different advanced cutting tools for machining such alloys. With a view to recommend a suitable cutting tool, the present work investigated various machinability characteristics of Incoloy 825 using an uncoated tool, chemical vapor deposition (CVD) of a bilayer of TiCN/Al₂O₃, and physical vapor deposition (PVD) of alternate layers of TiAlN/TiN-coated tools under varying machining conditions. The influence of cutting speed (51, 84, and 124 m/min) as well as feed (0.08, 0.14, and 0.2 mm/rev) was comparatively evaluated on surface roughness, cutting temperature, cutting force, coefficient of friction, chip thickness, and tool wear using different cutting tools. Although the CVD-coated tool was not useful in decreasing surface roughness and temperature, a significant reduction in cutting force and tool wear could be achieved with the same coated tool under a high cutting speed of 124 m/min. On the other hand, the PVD-coated tool outperformed the other tools in terms of machinability characteristics. This might be attributed to the excellent antifriction and antisticking property of TiN and good toughness due to the multilayer configuration in combination with a thermally resistant TiAlN phase. Adhesion, abrasion, edge chipping, and nose wear were the prominent wear mechanisms of the uncoated tool, followed by the CVD-coated tool. However, remarkable resistance to such wear was evident with the PVD TiAlN/TiN multilayer-coated tool.