Effect of nitrogen addition on the microstructure and mechanical behavior of 317L and 904L austenitic stainless steel welds

A systematic study of the effect of nitrogen addition on the microstructure and mechanical behavior of two different austenitic stainless steel welds, namely, 317L and 904L was carried out. For this, nitrogen content of the welds was altered by introducing different proportions of nitrogen gas into the argon shielding gas during welding. Nitrogen addition to 317L weld changed solidification mode from primary ferrite to primary austenite. As 904L weld solidify by primary austenitic mode, no change in the solidification mode was found with N addition. The results showed that, with rise in nitrogen content of the welds, various mechanical properties like ultimate tensile strength and ductility had improved significantly and that the welds prepared with 1 vol% N₂ in the shielding gas indeed failed in the base alloy making the weld stronger than the parent metal. It was noticed that the effect of N towards improving the mechanical properties 904L weld was higher than that found in the case of 317L weld.     

Synthesis of spherical Al2O3 and AlN powder from C@Al2O3 composite powder

A novel approach has been taken to produce (1) spherical Al₂O₃ particles by decarbonisation and (2) spherical AlN particles by nitridation and subsequent decarbonisation of C@Al₂O₃ composite particles. C@Al₂O₃ composite particles have been prepared by heterogeneous nucleation and crystallisation of Al(NO₃)₃ on surfactant encapsulated carbon nano particles followed by evaporative decomposition of the nitrate. Overpressure (0.4 MPa) of nitrogen and a temperature range (1723–1873 K) have been used for nitridation. Whiskers as well as spherical particles of AlN have been observed in the final product. The final product has been characterised by X-Ray Diffraction, Scanning Electron Microscope and Carbon–Hydrogen–Nitrogen content analysis by Elemental Analyser and the mechanism of the nitridation reaction has been analysed. The average size of the spherical AlN particles consisting of crystallites in nano-dimensions (30–50 nm) could be varied from 100 nm to 8 μm by changing the composition of the sol.     

Accurate modeling of monolithic inductors using conformal meshing for reduced computation

Accurate component modeling is a key factor to successful wireline and wireless circuit design in Si/SiGe BiCMOS and RF CMOS. This article presents the application of two planar electromagnetic simulation methods for reducing the memory and computation time requirement for accurate simulation of inductors fabricated with thick analog metal layers. First, a conformal subsectioning technique is briefly discussed in the context of reducing the numerical complexity of octagonal and circular spiral inductor analysis. Second, this article discusses a method for determining if more than a two-sheet model of thick metals is needed for accurate inductor simulation. Finally, the conformal mesh is applied to a 3.3-nH inductor fabricated using the IBM 0.13-/spl mu/m RF CMOS process technology. The simulated and measured results are compared.     

Routing on Meshes with Buses

We consider the problem of routing packets on an MIMD mesh-connected array of processors augmented with row and column buses. We give lower bounds and randomized algorithms for the problem of routing k-permutations (where each processor is the source and destination of exactly k packets) on a d-dimensional mesh with buses, which we call the (k,d)-routing problem. We give a general class of ``hard' permutations which we use to prove lower bounds for the (k,d)-routing problem, for all k,d≥ 1. For the (1,1)- and (1,2)-routing problems the worst-case permutations from this class are identical to ones published by other authors, as are the resulting lower bounds. However, we further show that the (1,d)-routing problem requires 0.72 ... n steps for d=3, 0.76 ... n steps for d=4, and slightly more than steps for all d≥ 5. We also obtain new lower bounds for the (k,d)-routing problem for k,d > 1, which improve on the bisection lower bound in some cases. These lower bounds hold for off-line routing as well. We develop efficient algorithms for the (k,1)-routing problem and for the problem of routing k-randomizations (where each processor has k packets initially and each packet is routed to a random destination) on the one-dimensional mesh and use them in a general (k,d)-routing algorithm which improves considerably on previous results. In particular, the routing time for the (1,d)-routing problem is bounded by steps with high probability (whp), whenever for some constant ε > 0, and the routing time for the (k,d)-routing problem is steps whp whenever for some constant ε > 0 and k≥ 3.6 ... d, matching the bisection lower bound. We then present a simple algorithm for the (2,2)-routing problem running in 1.39 ... n+o(n) steps whp. Finally, for the important special case of routing permutations on two-dimensional meshes with buses, the (1,2)-routing problem, we give a more sophisticated algorithm that runs in 0.78 ... n+o(n) steps whp. Received May 18, 1994; revised June 23, 1995.     

VEDA: a web-based virtual environment for dynamic atomic force microscopy

We describe here the theory and applications of virtual environment dynamic atomic force microscopy (VEDA), a suite of state-of-the-art simulation tools deployed on nanoHUB (www.nanohub.org) for the accurate simulation of tip motion in dynamic atomic force microscopy (dAFM) over organic and inorganic samples. VEDA takes advantage of nanoHUB's cyberinfrastructure to run high-fidelity dAFM tip dynamics computations on local clusters and the teragrid. Consequently, these tools are freely accessible and the dAFM simulations are run using standard web-based browsers without requiring additional software. A wide range of issues in dAFM ranging from optimal probe choice, probe stability, and tip-sample interaction forces, power dissipation, to material property extraction and scanning dynamics over hetereogeneous samples can be addressed.     

A multi-item transportation problem with fuzzy tolerance

This paper presents the recently introduced modified subgradient method for optimization and its effectiveness in a fuzzy transportation model. Here a multi-item balanced transportation problem (MIBTP) is formulated where unit transportation costs are imprecise. Also available spaces and budgets at destinations are limited but imprecise. The objective is to find a shipment schedule for the items that minimizes the total cost subjected to imprecise warehouse and budget constraints at destinations. The proposed model is reduced to a multi-objective optimization problem using tolerances, then to a crisp single-objective one using fuzzy non-linear programming (FNLP) technique and Zimmermann's method. The above fuzzy MIBTP is also reduced to another form of deterministic one using modified sub-gradient method (MSM). These two crisp optimization problems are solved by Genetic Algorithm (GA). As an extension, fuzzy multi-item balanced solid transportation problems (STPs) with and without restrictions on some routes and items are formulated and reduced to deterministic ones following FNLP and Zimmermann's methods. These models are also solved by GA. Models are illustrated numerically, optimum results of fuzzy MIBTP from two deductions are compared. Results are also presented for different GA parameters.     

Electrospun MgO/Nylon 6 Hybrid Nanofibers for Protective Clothing

Nano-Micro Letters - Magnesia (MgO) nanoparticles were produced from magnesite ore (MgCO3) using ball mill. The crystalline size, morphology and specific SSA were characterized by X-ray diffraction...     

In vitro corrosion behaviour of plasma nitrided Ti–6Al–7Nb orthopaedic alloy in Hanks solution

Titanium alloy (Ti–6Al–7Nb) used for orthopaedic applications was nitrided using a conventional dc plasmatechnique. Load-dependent microhardness measurements exhibit a hardness of 2087 H_v at 25 g load for the alloy nitrided at 900 8C for 8 h. Cyclic polarization measurement in Hanks solution show maximum corrosion rate and minimum areaof repassivation for the alloy nitrided for 8 h at 900 8C. Electrochemical impedance measurements show an increase in charge transfer resistance and decrease in double layer capacitance when compared to untreated alloy.     

CryptoCT: towards privacy preserving color transfer and storage over cloud

Multimedia Tools and Applications - Current trend toward cloud computing coupled with emerging technologies such as high definition images/videos and 360-degree videos, has led the requirement of...     

Chemical‐looping combustion — an overview and application of the recirculating fluidized bed reactor for improvement

This paper propose recirculating fluidized bed (RCFB) reactor for chemical‐looping combustion (CLC) to overcome some of the issues associated with the existing interconnected reactors arrangements like low residence time of bed material in the air reactor, high attrition of bed material in the cyclone separator, cluster formation in the air reactor, complex operation involving loop seals and high heat losses. RCFB has high solid circulation rate, long residence time, efficient fuel–oxygen carrier contact, low heat losses and low gas leak in between the reactors, as compared to the existing reactor configurations. A cold model study was performed on a Perspex made, semicircular, transparent RCFB reactor. A single RCFB reactor was operated in the alternate oxidation and fuel burning cycles to simulate the interconnected reactors arrangement for CLC. The generated experimental data has been used to predict the optimal RCFB reactor configuration for a RCFB‐based CLC power plant. Copyright © 2014 John Wiley & Sons, Ltd.