Investigating and modeling tool-wear rate in the ultrasonic machining of titanium

Titanium is known as the metal of the future because of its excellent combination of properties such as high specific strength, low thermal conductivity, and high corrosion resistance. There is a critical need for developing and establishing cost-effective methods for the machining of titanium, especially in terms of tool-wear optimization. This paper addresses the application of ultrasonic machining, an impact machining process for the cost-effective machining of commercially pure titanium (ASTM Grade-I) and evaluation of tool-wear rate under the effect of different process parameters. Tool material, abrasive material, slurry concentration, abrasive grit size, and power rating of the ultrasonic machine were included as the input factors in this investigation. The optimal settings of these parameters were determined through experiments planned, conducted, and analyzed using the Taguchi method. The significant parameters contributing most to the variation in tool-wear rate were identified and the results obtained were validated by conducting the confirmation experiments. Thereafter, the outcome of the Taguchi model has been used for developing a micro-model for tool-wear rate (TWR); using Buckingham’s pie theorem. A comparison of the experimental results obtained assists in the validation of the model.     

Ethyl-bis-triazinylpyridine (Et-BTP) for the separation of americium(III) from trivalent lanthanides using solvent extraction and supported liquid membrane methods

The present paper deals with the solvent extraction and supported liquid membrane studies on Ln(III)/An(III) separation using ethyl-bis-triazinylpyridine (Et-BTP) as the extractant. The solvent extraction studies involved evaluation of a) diluents, b) phase modifiers, c) stripping agents and d) role of feed acidity. Though reasonably high separation factor values were obtained when Et-BTP was used along with α-bromo carboxylic acids, the mixtures could not be used for liquid membrane studies due to unsatisfactory stripping. On the other hand, a combination of Et-BTP with chlorinated cobalt dicarbollide (CCD) in nitrobenzene resulted in significant Am(III) mass transfer when used in the solvent extraction as well as SLM studies. Improved transport, membrane stability, and decontamination from lanthanides were observed when the organic phase diluent composition was 60% nitrobenzene + 40% n-dodecane. Using 0.02 M Et-BTP along with 0.005 M CCD in 60% nitrobenzene + 40% n-dodecane, the SLM studies on a mixture of ²⁴¹Am, ¹⁵²Eu and ¹⁴⁷Nd in a feed containing 0.1 M HNO₃, indicated quantitative Am³⁺ transport in 3.5 h with co-transport of about 8% Nd³⁺ and 22% Eu³⁺.     

3-Dimensional numerical modeling of geosynthetic-encased granular columns

In this paper, series of three-dimensional (3-d) numerical modeling of geosynthetic-encased granular columns were performed both in model and prototype scale using FLAC^3D software to understand the lateral load carrying capacity of ordinary and geosynthetic encased granular columns (OGC and EGC). In the first part of the study, numerical modeling of direct shear tests were carried out. The soil in the direct shear box was reinforced with two different diameters of granular columns (50 mm and 100 mm) and three different patterns of arrangement (single, triangular and square) to study the effect of group confinement. The numerical simulations were carried out at four different confining pressures namely 15, 30, 45 and 75 kPa. From the numerical simulations it was observed that higher shear stresses are mobilized inside the granular column due to geosynthetic encasement and the magnitude of shear stress increases with increase in the normal pressure. It was found that the tensile forces in the geosynthetic encasement were mobilized both in circumferential and vertical directions, which helps in mobilizing additional confinement in the granular column. In the second part, the influence of the geosynthetic encasement of granular column treated soft ground was demonstrated through 3-dimensional slope stability analyses.     

Synthesis, Characterization and Catalytic Properties of Vanadium Substituted Hexagonal Mesoporous Aluminophosphate Molecular Sieves

Vanadium substituted hexagonal mesoporous aluminophosphate (VHMA) molecular sieves were synthesized hydrothermally. Various physicochemical studies, viz., XRD, TEM, DRUV–VIS, EPR, N₂ sorption were used to find the location of vanadium ions in the VHMA matrix and to check the mesoporosity of the sample. The catalytic activity of VHMA was evaluated, under mild reaction conditions, for the oxidation of cyclohexane reaction, which mainly gave cyclohexanol and cyclohexanone along with a very small amount of a secondary product, viz., cyclohexyl acetate. A comparative study, with other vanadium containing molecular sieves, viz., VMCM-41, VAPO-5 and VS-1, on the application of VHMA catalyst reveal that the latter exhibits excellent activity, selectivity and stability to leaching for the oxidation reaction of cycloalkanes, including bulkier molecules such as cyclododecane.     

Boronic acid functionalized superparamagnetic iron oxide nanoparticle as a novel tool for adsorption of sugar

Synthesis of boronic acid functionalized superparamagnetic iron oxide nanoparticles has been reported. Magnetite nanoparticles were prepared by simple co-precipitation from Fe²⁺ and Fe³⁺ solution. m-Aminophenyl boronic acid was attached to iron oxide particles through 3,4-dihydroxy benzaldehyde through CN bond. X-ray diffraction and selected area electron diffraction have shown the formation of inverse spinel phase magnetite of both as prepared and functionalized magnetite particles. FTIR shows attachment of boronic acid-imine onto iron oxide surface through enediol group. Transmission electron microscopy shows well dispersion of boronic acid functionalized particles of size 8 ± 2 nm. Vibration sample magnetometry shows both the particles are superparamagnetic at room temperature having saturation magnetization (Ms) 52 emu/g. In this work the affinity of these boronic acid functionalized particles towards sugar binding was studied taking dextrose sugar as a model. The influence of pH and sugar concentration has been extensively investigated. The results show that such boronic acid modified superparamagnetic particles are efficient support for sugar separation having maximum sugar loading capacity (60 µg/50 µl) at pH 8.     

Recent advances and evolution of WLAN and WMAN standards [guest editorial]

Standardization of wireless technologies is a continuous process, and even established standards are updated and modified in response to changes in the technology and the marketplace. One such example is the successful IEEE 802.11 standard for wireless local area networks (WLANs), which was originally designed for 1 and 2 Mb/s traffic, and is now being upgraded to support 600 Mb/s in 802.11n and being considered as a high-throughput (up to 1 Gb/s) wireless interface for the nomadic scenarios of the next generation of wireless systems. Similarly, enhancements to the IEEE 802.16 standard for wireless metropolitan area networks (WMANs) are being considered to develop a mobile air interface with support for up to 100 Mb/s in high mobility scenarios. This continuous evolution of the IEEE 802.11 WLAN and 802.16 WMAN standards is made possible with new innovation and contribution from both academia and industry. Given the rapid growth of these technologies, it is important to understand what new application scenarios have triggered the recent developments within WLAN and WMAN standards, how they are evolving, the technological challenges they face, and the opportunities for both the industry and research communities. In this issue, from a large number of submissions, we have selected five key articles for inclusion, which provide the reader with ongoing developments in these standards, technology roadmaps, current research challenges, and comprehensive evolution of these technologies, as well as deployment experience and application requirements.     

Synthesis of hydroxyapatite/poly(vinyl alcohol phosphate) nanocomposite and its characterization

Hydroxyapatite (HAp)/poly(vinyl alcohol phosphate) (PVAP) nanocomposite has been prepared using a solution‐based method varying HAp from 10 to 60% (w/w). X‐ray diffraction, Fourier transform infrared absorption spectra (FTIR), and thermal analysis have indicated the presence of bonding between HAp particles and PVAP matrix. Transmission electron microscope analysis shows the needle‐like crystals of HAp powder having a diameter of 6–10 nm and a length of 26–38 nm. The surface roughness and the homogeneous dispersion of HAp particles in the polymer matrix have been observed by scanning electron microscopy. Particle size distribution analysis shows the narrow distribution of hydrodynamic particles in the polymer matrix. The tensile stress–strain curves show the improvement in mechanical properties of the composites with increase in amount of HAp particles loading. The composites along with polymer are highly hemocompatible. The use of PVAP promotes the homogeneous distribution of particles on the polymer matrix along with strong particle–polymer interfacial bonding, which has supported the improvement in mechanical properties of the composites. The prepared HAp/PVAP composite with uniform microstructure would be effective to act as a potential biomaterial. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Scheduling of wireless control networks based on IEEE 802.15.4 networks: Mixed traffic environment

This paper describes a scheduling method of wireless control networks for factory automation using IEEE 802.15.4 networks. The superframe of IEEE 802.15.4 is used for the transmission of real-time mixed data for wireless control systems. The schedulability of real-time data is defined, and scheduling algorithms are proposed for the efficient transmission of real-time mixed traffic. Simulation results show enhancements in the average network utilization and packet drop rate for real-time data.