Effect of Lead Addition and Milling on Densification and Mechanical Properties of 6061 Aluminium Alloys

In the present work, one batch of prealloyed 6061Al powder was mixed with different lead compositions (5, 10, 15 vol.%) and another set with same composition was ball-milled for 5 h at 300 rpm. Microstructural features such as lattice constant, crystallite size, particle size and morphology were studied using XRD, particle size analyzer and SEM. Both the as-mixed as well as ball-milled powders were compacted at 300 MPa and sintered under N₂ atmosphere for 1 h in tube furnace at 590 °C. The ball milling of 6061Al alloy powder improved sinter density and densification while lead addition showed negligible influence on these parameters. The microstructure of as-mixed 6061Al–Pb alloys exhibited equiaxial morphology whereas ball-milling resulted in elongated grains with uniform lead distribution. Quasi-static compressive mechanical behavior was investigated for 6061Al–Pb alloys at 1 × 10^?3 s^?1 strain rate. Results indicated that ultimate compressive and yield strength were sensitive to milling and lead volume fraction.     

Influence of quenching methods on martensitic transformation and mechanical properties of P/M processed Cu–Al–Ni–Ti shape memory alloys

The effect of quenching conditions on phase transformation characteristics and microstructural features of Cu–Al–Ni–Ti shape memory alloys (SMAs) have been studied. The alloys were synthesised via conventional powder metallurgy process using elemental metal powders. Four different quenching techniques, such as (a) two-step quenching, first to 100°C and then to 0°C; (b) two-step quenching, initially to 40°C and later to 0°C; (c) direct quenching to 40°C and (d) direct quenching to 0°C, were used. The microstructural features and phase transformations that the alloys had undergone were studied using FE-SEM and XRD techniques. The martensitic phase transformation analyses were carried out by differential scanning calorimeter while the mechanical properties were studied by microhardness and flexural bending tests. The results obtained clearly indicate that the quenching routes followed have a remarkable influence on the properties of Cu-based SMAs.     

Self-assembly and magnetically induced phase transition of three-dimensional colloidal photonic crystals

Charged superparamagnetic colloidal Fe(3)O(4)@SiO(2) core-shell particles were chosen as model dipolar soft spheres to study their crystallization and magnetically induced phase transition in suspensions. The 3D colloidal crystals feature excellent magnetically responsive photonic properties with strong diffraction, fast response and wide tunability.     

Epidemiology and risk management of listeriosis in India

Listeria monocytogenes is a foodborne pathogen that can cause serious invasive illness, mainly in certain well-defined high-risk groups, including elderly and immunocompromised patients, pregnant women, newborns and infants. In India, this pathogen has been isolated from humans, animals and foods. The incidence of Listeria is generally comparable to those reported elsewhere in the world. In humans, maternal/neonatal listeriosis is the most common clinical form reported. Among animal populations, spontaneous abortions, subclinical mastitis, meningoencephalitis and endometritis were the commonest forms reported. The disease largely remains undiagnosed and under reported. From reported analyses of a variety of foods for Listeria, milk and milk products, meat and meat products, seafood and vegetables have been reported to be contaminated in India. The legal framework for microbiological safety of foods against microbes including L. monocytogenes is summarised. The epidemiological studies would help in understanding of the sources of infection and persistence and their risk assessment, routes of transmission, clinical forms and allow for better management of the infection.     

Site-wide low-grade heat recovery with a new cogeneration targeting method

One of the key performance indicators for designing site utility systems is cogeneration potential for the site. A new method has been developed to estimate cogeneration potential of site utility systems by a combination of bottom-up and top-down procedures, which allows systematic optimization of steam levels in the design of site utility configurations. A case study is used to illustrate the usefulness of the new cogeneration targeting method and benefits of optimizing steam levels for reducing the overall energy consumptions for the site. Techno-economic analysis has been carried out to improve heat recovery of low-grade waste heat in process industries, by addressing a wide range of low-grade heat recovery technologies, including heat pumping, organic Rankine cycles, energy recovery from exhaust gases, absorption refrigeration and boiler feed water heating. Simulation models have been built for the evaluation of site-wide impact associated with the introduction of each design option in industrial energy systems in the context of process integration. Integration of heat upgrading technologies within the total site has been demonstrated with a case study for the retrofit scenario.     

Engineering spin propagation across a hybrid organic/inorganic interface using a polar layer

Spintronics has shown a remarkable and rapid development, for example from the initial discovery of giant magnetoresistance in spin valves to their ubiquity in hard-disk read heads in a relatively short time. However, the ability to fully harness electron spin as another degree of freedom in semiconductor devices has been slower to take off. One future avenue that may expand the spintronic technology base is to take advantage of the flexibility intrinsic to organic semiconductors (OSCs), where it is possible to engineer and control their electronic properties and tailor them to obtain new device concepts. Here we show that we can control the spin polarization of extracted charge carriers from an OSC by the inclusion of a thin interfacial layer of polar material. The electric dipole moment brought about by this layer shifts the OSC highest occupied molecular orbital with respect to the Fermi energy of the ferromagnetic contact. This approach allows us full control of the spin band appropriate for charge-carrier extraction, opening up new spintronic device concepts for future exploitation.     

Attainable regions of reactive distillation—Part III. Complex reaction scheme: Van de Vusse reaction

The main underlying principle behind the application of reactive distillation (RD) for selectivity enhancement is to facilitate the separation of selected components and favorably manipulate the composition profiles in the reactive zone to expedite the desired reaction. In this paper, a geometric approach of attainable region (AR), which is already developed for conventional reactor network, is extended further to include few representative RD configurations. We define new RD building blocks and the corresponding composition vectors that indicate a need of networking of RD units among themselves and with conventional reactors to enlarge the set of attainable compositions. A model reaction scheme of van de Vusse type ) is studied as an illustrative example and an algorithm is developed to obtain the attainable region for the given kinetics, feed composition and relative volatilities. In almost all the different cases, which are studied by varying the kinetics and volatility pattern, network consisting of RD units performs better than the conventional reactor network.     

Study of effect of binders and loading pressures on the performance of the time delay pyrotechnic compositions

ABSTRACT

An experimental investigation was carried out to determine the effect of binders and loading pressures on burning performance of B/BaCrO₄ and Si/PbO/Pb₃O₄ delay compositions. The consolidated density and percent theoretical maximum density (%TMD) of these compositions were also studied with different binders and at multiple loading pressures. Carboxyl methyl cellulose (CMC), dextrin, and fish glue with varying wt. % were used as binders. It was observed that the burning rate of these delay compositions was inversely proportional to the binder content. The burning rate of B/BaCrO₄ delay composition was 71.0 mm/s without binder. The burning rate decreased to 38.1 mm/s by adding 3.0 % fish glue. When 1.0 % CMC was added to the mixture, the burning rate decreased to 61.8 mm/s. By adding 3.0 % dextrin to the delay composition, the burning rate decreased to 38.2 mm/s. The burning rate of Si/PbO/Pb₃O₄ delay mixture was 38.6 mm/s without binder. The burning of this mixture decreased to 16.4 mm/s by adding 1.0 % fish glue. The loading pressures were varied from 103 to 414 MPa. The effect of loading pressures on the burning rate of both the delay compositions was marginal. The burning rate of B/BaCrO₄ delay mixture decreased with the increase in loading pressure. On contrary, the change in burning rate of Si/PbO/Pb₃O₄ pyrotechnic delay composition was minimal by varying the loading pressures. Results also revealed that loading pressures of 345 and 348 MPa produced the minimum standard deviation in burning rate of B/BaCrO₄ and Si/PbO/Pb₃O₄ compositions. The consolidated density and %TMD of both mixtures increased by adding binders and increasing the loading pressures.     

Ranking of software engineering metrics by fuzzy‐based matrix methodology

This research paper presents a framework for ranking of software engineering metrics based on expert opinion elicitation and fuzzy‐based matrix methodology. The proposed methodology is able to accommodate the imprecise and inexact data involved in the problem of ranking of software engineering metrics, vagueness and ambiguity occurring during expert (human) decision making and to depart from the complexity of formulation of the objective and the constraint function. The matrices lend themselves to mechanical manipulations and are useful for analyzing and deriving systems functions expeditiously to meet the objectives. The current research is based on software engineering metrics identified in an earlier study conducted by Lawrence Livermore National Laboratory. A set of ranking criteria were identified. Software engineering metrics are then ranked in ascending order using experts' opinion in accordance with the value of Permanent function on their criteria matrix. The proposed methodology has also been compared with other known methodologies. Copyright © 2011 John Wiley & Sons, Ltd.