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.     

Investigation of TiAlN coated roller burnishing on Al-(B4C)p MMC workpiece material

Burnishing avoids the need for super finishing operations after the conventional turning process, to enhance the surface quality. This paper deals with the surface modifications of Al(B₄C)_p Metal Matrix Composites (MMC) workpiece material after burnishing with a TiAlN coated WC roller. The burnishing speed, lubrication type, burnishing passes, and coating were the input parameters. Surface hardness and roughness after the burnishing were studied. It was found that the coating on the WC roller had enhanced the hardness in the workpiece after burnishing in the case of Al-5?wt.% (B₄C)_p, under all conditions. The effect of the coating on the work piece surface hardness was not significant with Al-10?wt.% (B₄C)_p. While burnishing Al-5?wt.% (B₄C)_p, the minimum surface roughness combined with maximum surface hardness was obtained, during the third pass under dry condition using uncoated rollers. The number of passes to achieve the desired surface conditions reduced, on using coated rollers with kerosene as the lubricant.     

Preparation and functional evaluation of agarose derivatives

A facile microwave‐assisted one‐pot synthesis of sodium carboxymethylagarose and calcium carboxymethylagarose from Gracilaria dura agarose (Ag) has been described. The process is user friendly, and the highest degree of substitution was obtained within 15 min compared with the conventional method, which requires more than 3 h. Solubility and gelling behavior of the modified Ag products were found to be dependent on degree of substitution of the products. The characterizations were done by using Fourier transform infrared spectroscopy, ¹H‐ and ¹³C‐nuclear magnetic resonance spectroscopy, thermogravimetric analysis, scanning electron microscopy, Inductively coupled plasma spectrophotometry (ICP), rheology, conductometer analysis, and DNA gel electrophoresis. These agarose derivatives were easily soluble in water and exhibited low thermal hysteresis, improved conductivity, and improved the DNA resolution ability of the parent G. dura Ag hydrogels. These hydrogels may have potential applications in the areas including electrochemical devices, microbiology, biomedical, and pharmaceuticals fields. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40630.     

Dependence of photoluminescence and electrical properties with rapid thermal annealing in nitrogen-implanted ZnO films

Undoped (as-grown) ZnO films grown by pulsed laser deposition on Al₂O₃ (0001) substrates were doped with nitrogen by means of an ion implantation process. Post-implantation annealing behavior in the temperature range between 500 and 700 °C has been studied by photoluminescence and Hall effect measurements. The implanted films show no peak other than the excitonic recombination emission in the as-implanted state, however, after rapid thermal annealing at 700 °C they reveal a nitrogen acceptor related emission at 3.273 eV. The as-implanted ZnO films show more electron concentrations than the as-grown, unimplanted ZnO film. In contrast, after annealing, the electron concentration in the implanted films is significantly reduced, indicating that the incorporated nitrogen becomes activated after the thermal annealing, then produces holes and eventually compensates for certain amount of electrons. The results imply that a proper nitrogen implantation and subsequent annealing may be a way to produce p-type ZnO films.     

Optimum lipid production using agro-industrial wastewater treated microalgae as biofuel substrate

Abundant wastewater discharges from palm oil industries in tropical nations being a valuable resource of biodiesel need proper exploration. Research hinted that such wastewater as economical nutrient source or substrate can support the cultivation of microalgae. In this experiment, we have tested the growth and lipid production of five different microalgal strains in palm oil mill effluent (POME). POME as a biofuel substrate is demonstrated to be lucrative for microalgae-assisted lipids production. POME is rich in macro- and micronutrients can be used as a growth medium for algal growth in order to reduce the growth medium cost and environmental pollutions. Among the five microalgal strains tested, Chlorella sorokiniana revealed optimum biomass and lipid production. The productivity was evaluated in terms of chlorophyll content, growth rate, biomass, and lipid content, which discerned to be 0.099/day, 8.0 mg/L day and 2.68 mg/mg cell dry weight (CDW). Furthermore, in this study, an optimization study was carried out to enhance the microalgae to produce high lipid content using carbon-to-nitrogen ratio and different light/dark periods. The presence of nitrogen combined glucose (with a carbon-to-nitrogen ratio 100:7) as an alternative source to carbon displayed higher lipid production of 2.68 (mg/mg CDW) by C. sorokiniana. This study confirms that 8:16 h light/dark condition at C:TN ratio of 100:7 supported to produce high lipid content of 17 mg lipid/mg CDW. The above results revealed that POME could be a suitable growth media for the alga C. sorokiniana to improve the maximum lipid yield for biofuels production.     

Rechargeable Lithium Metal Batteries with an In-Built Solid-State Polymer Electrolyte and a High Voltage/Loading Ni-Rich Layered Cathode

Solid-state batteries enabled by solid-state polymer electrolytes (SPEs) are under active consideration for their promise as cost-effective platforms that simultaneously support high-energy and safe electrochemical energy storage. The limited oxidative stability and poor interfacial charge transport in conventional polymer electrolytes are well known, but difficult challenges must be addressed if high-voltage intercalating cathodes are to be used in such batteries. Here, ether-based electrolytes are in situ polymerized by a ring-opening reaction in the presence of aluminum fluoride (AlF₃) to create SPEs inside LiNi_0.6Co_0.2 Mn_0.2O₂ (NCM) || Li batteries that are able to overcome both challenges. AlF₃ plays a dual role as a Lewis acid catalyst and for the building of fluoridized cathode–electrolyte interphases, protecting both the electrolyte and aluminum current collector from degradation reactions. The solid-state NCM || Li metal batteries exhibit enhanced specific capacity of 153 mAh g⁻¹ under high areal capacity of 3.0 mAh cm⁻². This work offers an important pathway toward solid-state polymer electrolytes for high-voltage solid-state batteries.     

Cloud Security Service for Identifying Unauthorized User Behaviour

Recently, an innovative trend like cloud computing has progressed quickly in Information Technology. For a background of distributed networks, the extensive sprawl of internet resources on the Web and the increasing number of service providers helped cloud computing technologies grow into a substantial scaled Information Technology service model. The cloud computing environment extracts the execution details of services and systems from end-users and developers. Additionally, through the system’s virtualization accomplished using resource pooling, cloud computing resources become more accessible. The attempt to design and develop a solution that assures reliable and protected authentication and authorization service in such cloud environments is described in this paper. With the help of multi-agents, we attempt to represent Open-Identity (ID) design to find a solution that would offer trustworthy and secured authentication and authorization services to software services based on the cloud. This research aims to determine how authentication and authorization services were provided in an agreeable and preventive manner. Based on attack-oriented threat model security, the evaluation works. By considering security for both authentication and authorization systems, possible security threats are analyzed by the proposed security systems.     

Optimum tolerance synthesis for complex assembly with alternative process selection using Lagrange multiplier method

Any part cannot be manufactured to the required nominal dimensions due to inherent variations in workmanship, material, and machine. The specification of tolerance on part dimensions plays a major role on performance, quality, and cost of the product. Distribution of tolerance among the components of an assembly is known as tolerance allocation. The selection of alternative processes for tolerance allocation also plays a vital role in reducing manufacturing cost. Near-optimal allocated tolerances are obtained using nontraditional optimization techniques in which the solutions are achieved randomly. Also, there is a chance for omitting the better process for allocation. The results of successive run of the program based on these techniques will not yield consistent results. An attempt has been made in this work to solve the above problem using Lagrange multiplier method for complex assemblies with univariate search method. The methodology has been demonstrated on wheel mounting assembly. The example product after implementing the proposed method would yield 1.4% savings in manufacturing cost as compared with the cost obtained by Singh.     

Determination of Amylose Content in Different Starches Using Modulated Differential Scanning Calorimetry

A simple calorimetric method for determination of amylose content in starch is reported. Starches were heated in the presence of two common surfactants, viz., sodium dodecyl sulphate (SDS) and cetyltrimethylammonium bromide (CTAB), and the enthalpies of melting of the amylose‐surfactant complexes were determined using Modulated Differential Scanning Calorimetry (MDSC). A large number of native starches including cereal, root and pea starches were examined. The results were compared with those obtained by iodimetry and gel permeation chromatography (GPC) for all the starches. There was a good correlation between the values from iodimetry and GPC with those obtained using the surfactants. Both surfactants seemed to work equally well, even for those starches with about 40% amylose content. However, in case of SDS higher standard deviations were usually obtained than for CTAB in the determination of transition enthalpies.