Analysis of Nanofluids as Cutting Fluid in Grinding EN-31 Steel

Nano-Micro Letters - Grinding requires high specific energy which develops high temperatures at wheel work piece interface. High temperatures impair work piece quality by inducing tensile residual...     

Biodegradation of gelatin–g-poly(ethyl acrylate) copolymers

Gelatin-g-poly(ethyl acrylate) copolymers were prepared in an aqueous medium, using K₂S₂O₈ initiator. The composition of the graft copolymers was dependent upon temperature and duration of the reaction. The number of grafting sites was small and molecular weight of the grafted poly(ethyl acrylate) branches was high. Three copolymer samples with grafting efficiencies of 33.3%, 61.0%, and 84.0%, were tested for their microbial susceptibility in a synthetic medium employing a mixed inoculum of Bacillus subtilis, Pseudomonas aeruginosa, and Serratia marcescens and the percent weight losses were 12%, 10.1%, and 6.0%, respectively, after 6 weeks of incubation. The extent of degradation seems to decrease with increasing grafting efficiency. There was initial rapid weight loss accompanied by the exponential increase in bacterial population and pH of the culture medium during the first week. The nitrogen analysis also showed the utilization of the polymer. A parallel set of experiments, carried out by employing the samples as the only source of both carbon and nitrogen, showed a marginal but definite increase in the utilization of the polymer.     

FT-Raman and FT-IR vibrational spectroscopic studies of nanocrystalline Ba2RESbO6 (RE = Sm, Gd, Dy and Y) perovskites

The nanoparticles of Ba₂RESbO₆ (RE = Sm, Gd, Dy and Y) were synthesized using auto ignition combustion process. The structure and phase purity of the as-prepared nanopowders were examined by X-ray diffraction pattern. A systematic analysis of the structure of the four compounds was carried out for the first time by recording Raman and IR spectra. The four Raman active modes A_1g, E_g and 2F_2g were observed as strong or medium intense bands in the Raman spectra and the IR active F_1u(1) mode is obtained as a strong absorption band around 630 cm⁻¹ in all the four compounds. Hence it is confirmed that the above compounds were crystallized in the cubic symmetry with space group.     

Arching in Soils Applied to Inclined Mine Stopes

Determination of stress distribution, giving due consideration to arching mechanism within minefill stopes, is of great importance because of its influence on the ground stability, ore recovery, and cost effectiveness. Most of the past studies on the stress determination have been applied to vertical stopes, and there is a lack of research study, especially analytical work, on inclined stopes. This study provides an analytical expression for the vertical stress at any depth within the inclined backfilled stopes by incorporating an arching effect within the backfill. Comparatively, the results obtained from this study agree well with other limited analytical and numerical results reported in the literature. A parametric study is undertaken to investigate the effect of various parameters involved in the proposed analytical expression. The results obtained reveal that stope geometry, fill properties, and stope inclination are critical factors in predicting the stress distribution in mine stopes.     

Influence of low-frequency electromagnetic fields on living organisms

Recent research reports appear to indicate a real possibility that the low-frequency electromagnetic field produced by the power transmission and distribution network presents a health problem. A critical assessment of the available information is presented here. The state of knowledge, available evidence and conflicting reports indicate a definite need for interim action by the power industry. New direction for analytical research, possible interim avoidance measures, proper advice to clients and the public are discussed. Detailed mathematical modeling for the linear and nonlinear dynamics of DNA and the chromosome as a whole is suggested.     

Effect of nozzle angle and depth of cut on grinding titanium under cryogenic CO2

Grinding force and grinding energy are the significant factors associated with the grinding process. The higher heat at the contact zone leads to dulling grits and frequent breakage of grit particle resulting in increase of the grinding force. This problem can be met by bringing down the temperature at the contact zone. The oil-based coolant fails to eliminate the heat at the grinding zone. Hence, the approach of cryogenic coolant is required for this problem. In the present study, an experimental work has been made on the grinding Ti-6Al-4V under cryogenic carbon dioxide (CO₂) and conventional coolant condition. Grinding experiments were performed with an electroplated cubic boron nitride (CBN) wheel, with two factors such as nozzle inclination angle and depth of cut (DOC). The output response parameters considered were surface roughness (R_a), tangential force (F_t), normal force (F_n) grinding zone temperature (GT), and specific energy. The effect of CO₂ and wet coolant on the chip morphology and surface modification in grinding Ti-6Al-4V was analyzed. The experimental result indicates when cryogenic CO₂ was used as a coolant the F_t is reduced from 3 to 21% and 2 to 99% in F_n. The R_a was reduced by 333% and GT by 48% over conventional grinding.     

Preparation,structural, and characterizations of SnO2-coated TiNb2O7 anode materials for lithium-ion batteries

SnO₂-coated TiNb₂O₇ powders were synthesized via the solution coating method in the present research. The SnO₂ layers with a thickness of 3–5 nm were homogeneously coated on the surface of TiNb₂O₇ particles. TiNb₂O₇ coated with SnO₂ of 5 mol% with high Li⁺ diffusion coefficient delivered the discharge capacity of 319.5 mAh/g, which was 6.6% higher than that of the non-coated samples. The enhancement of capacity for the coated TiNb₂O₇ was owing to the low charge-transfer resistance of 17.5 Ω in contrary to the non-coated TiNb₂O₇ (27.8 Ω). SnO₂-coated TiNb₂O₇ possessed an improved capacity retention of 85.2% at 5 C after 100 cycles, superior to the non-coated TiNb₂O₇ (79.8%). On the other hand, the excessive amounts of SnO₂ coating led to the reduction in the capacity of the prepared samples. The excessive amounts of SnO₂ layers suppressed the Li⁺ diffusion and increased the charge-transfer resistance. The obtained results in this study indicated that coating of TiNb₂O₇ with appropriate amounts of SnO₂ significantly improved the electrochemical performance of TiNb₂O₇.     

Electrical behavior of dual‐morphology polyaniline

An attempt was taken to synthesize two types of polyaniline (PANI) with and without solvent followed by drying in air and vacuum oven conditions resulting different morphologies. The PANIs were prepared by chemical oxidative polymerization and studied with respect to their morphological features. Scanning electron microscopy, thermogravimetric analysis, X‐ray diffractometry, Fourier transform infrared spectroscopy, and ultraviolet–visible spectroscopy techniques were used for the characterization studies. The PANI synthesized with a solvent had a mixed morphology (fibrillar and granular), whereas PANI synthesized without a solvent had only a granular morphology. The direct‐current electrical conductivities of the samples were evaluated with an electrometer. We observed that the PANIs with mixed morphology (with solvent) were more electrically conducting than those with a single morphology (without solvent). On drying in vacuo, the conductivity of PANI decreased from 3.3 × 10^?2 to 0.3 × 10^?2 S/cm with solvent treatment, whereas it decreased from 0.1 × 10^?2 to 0.3 × 10^?3 S/cm without solvent treatment. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44091.     

Microstructure of rapidly-quenched ZrO2-SiO2 glass-ceramics fabricated by container-less aerodynamic levitation technology

In this work, an aerodynamic levitation technology (ALT) was utilized to prepare ZrO₂-SiO₂ glass-ceramics with two different ZrO₂ contents, that is, 35 mol% and 50 mol%. The glass-ceramics were partially melted at ∼2000°C or fully melted at ∼3000°C by ALT, followed by rapid quenching to obtain spherical glass-ceramic beads. The phase compositions and microstructures of the glass-ceramics were characterized. Crystallization of ZrO₂ occurred during the solidification process and ZrO₂ content, processing temperature, and the addition of yttrium (3 mol%) affected the crystalline phase of ZrO₂. No ZrSiO₄ or crystalline SiO₂ were formed during the solidification process and the glass-ceramics were away from thermodynamic equilibrium due to rapid quenching. The glass-ceramics showed a microstructure of irregular-shaped ZrO₂ micro-aggregates embedded in an amorphous SiO₂ matrix, with lamellar twins and lattice defects formed within ZrO₂ crystals. For samples prepared at ∼3000°C, a liquid-liquid phase separation occurred in the melt, which eventually resulted in the formation of large and irregular-shaped ZrO₂ aggregates. In comparison, for samples prepared at ∼2000°C, pre-existed ZrO₂ crystals formed during heating acted as nucleation sites during the cooling process, followed by grain growth to form large ZrO₂ aggregates. Solidification and microstructure formation mechanisms were proposed to elucidate the solidification process during rapid cooling and the microstructure of the glass-ceramics obtained.     

Opposition Based Artificial Flora Algorithm for Load Balancing in LTE Network

In recent years, telecommunication is progressed due to the development of Long-Term Evolution (LTE) standards. This LTE network provides high-speed wireless communication for mobile devices and satisfies the requirements of customers from multi-cells. However, due to the congestion of mobile devices, each cell in the network may get overloaded. So, load balancing is the main challenge to the LTE network for reducing congestion or load in the cell. For load balancing, the optimal cell selection method is presented in this paper. Initially, the load factor of each cell is estimated. Then the load factor is compared with the predefined threshold load value. After the comparison, the heavy loaded cell handover the users to the optimal cell or cell with minimum load. This optimal cell is selected with the Opposition Based Artificial Flora (OAF) algorithm. Simulation results show that the proposed approach decreases 6% of the call blocking ratio (CBR) and 14% of Call Dropping Ratio (CDR) than the previous approaches.