Fracture strength of various lay-ups of carbon/epoxy laminates using the modified inherent flaw model

Modifications are made in the inherent flaw model of Waddoups, Eisenman and Kaminski (known as the WEK model) for accurate prediction of notched tensile strength of composite laminates containing a sharp notch. To examine the adequacy of the model, fracture data of center cracked carbon/epoxy composite laminates with various lay-ups are considered. The notched strength estimates are found to be close to the test results.     

A new algorithm for optimum tolerance allocation of complex assemblies with alternative processes selection

Allocating tolerance to sub-components of a complex assembly with alternative processes selection by using Lagrange’s multiplier method is tedious as well as difficult. The present work is aims to solve the problem with simple effort in three stages. In the first stage, the maximum of two processes are selected from the alternative processes of each component and these two processes correspond to the smaller sum of difference in manufacturing cost. A hybrid optimum tolerance allocation method is developed in a second and third stage by combining Tabu search (TS) and heuristic approach. Application of the proposed algorithm is demonstrated on complex tolerancing products like knuckle joint and wheel mounting assembly. For the same manufacturing conditions, compared with tolerance synthesis by Singh method, the proposed method saved nearly $74,880 and $479,520, respectively, per year in manufacturing costs of knuckle joint and wheel mounting assembly.     

Phase study in the Na-Sr-U-O system: Characterization of new phase

In continuation with the earlier work for phase studies of Rb-Sr-U-O and Cs-Sr-U-O systems, the subsolidus phase relations in Na-Sr-U-O quaternary system were determined at 850 °C in air atmosphere. A novel quaternary phase Na₈Sr₂U₆O₂₄ in the Na-Sr-U-O system was synthesized by heating the respective oxides at 850 °C in air. XRD data of Na₈Sr₂U₆O₂₄ was indexed on a cubic system with lattice parameter a = 0.8326 nm and was found isostructural with K₈Sr₂U₆O₂₄ and Rb₈Sr₂U₆O₂₄. A pseudo-ternary phase diagram of Na₂O-SrO-UO₃ was drawn using the new quaternary compound and various phase fields were established by X-ray powder diffraction analysis. The structure of Na₈Sr₂U₆O₂₄ was derived from the powder data and structural parameters were refined by the Rietveld profile method.     

Control of nano-sized interlayer space of lamellar vanadyl benzylphosphate

Nano-sized interlayer space of lamellar vanadyl benzylphosphate was controlled by water content in starting solution. Depending on the water content, three types of lamellar vanadyl benzylphosphate having basal spacings of 1.4 nm, 1.9 nm and 2.3 nm were obtained. It was suggested that the difference in the concentrations of benzyl and hydroxyl groups in the interlayer leads to the variation of the interlayer space.     

Ascorbic Acid-Assisted Eco-friendly Synthesis of NiCo<Subscript>2</Subscript>O<Subscript>4</Subscript> Nanoparticles as an Anode Material for High-Performance Lithium-Ion Batteries

We have synthesized NiCo₂O₄ nanoparticles (NCO NPs) using an ascorbic acid-assisted co-precipitation method for the first time. When NCO NPs are used as an anode material for lithium-ion batteries, the cell exhibits superior lithium storage properties, such as high capacity (700 mA h g^?1 after 300 cycles at 200 mA g^?1), excellent rate capabilities (applied current density range 100–1200 mA g^?1), and impressive cycling stability (at 1200 mA g^?1 up to 650 cycles). The enhanced electrochemical properties of NCO NPs are due to the nanometer dimensions which not only offers a smooth charge-transport pathway and short diffusion paths of the lithium ions but also adequate spaces for volume expansion during Li storage. Hence, this eco-friendly synthesis approach will provide a new strategy for the synthesis of various nanostructured metal oxide compounds, for energy conversion and storage systems applications.     

Easy Access to 1‐Amino and 1‐Carbon Substituted Isoquinolines via Cobalt‐Catalyzed C?H/N?O Bond Activation

A green atom‐economical method for the synthesis of highly functionalized 1‐amino and 1‐carbon substituted isoquinolines from the reaction of N′‐hydroxybenzimidamides and aryl ketoximes, respectively, with alkynes via pentamethylcyclopentadienylcobalt(III)‐catalyzed C H/N O bond activation is described. The external oxidant‐free annulation reaction uses the =NOH moiety in N′‐hydroxybenzimidamides or N‐aromatic ketone oximes as the directing group and internal oxidant. This first row transition metal‐catalyzed annulation serves as an efficient alternative for the synthesis of isoquinolines, as water is the only by‐product and expensive noble metals such as rhodium(III), iridium(III), palladium(II), and ruthenium(II) are not required. The reaction proceeds via C H activation, alkyne insertion, reductive elimination, and N O activation.

     

Fast pyrolysis kinetics of expanded polystyrene foam

Fast pyrolysis of polymers, biomass and other substances is of great interest in various applications. For example, in the lost foam casting process, kinetic information about expandable polystyrene (EPS) decomposition under extremely high‐heating rate conditions is essential for further process development. A simple laboratory‐scale fast pyrolysis technique has been developed and demonstrated for elucidation of EPS decomposition kinetics. Pyrolysis experiments were performed at different reaction temperatures. The cumulative gaseous yields were determined using a flame ionization detector (FID) connected in series with the fast pyrolysis reactor. The governing equations for a semibatch reactor type were modified and applied to obtain kinetic parameters (activation energies and the pre‐exponential rate constants) for the EPS decomposition process. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

Photocatalytic degradation of phenol in a rotating annular reactor

Batch photocatalytic degradation studies of phenol were conducted in an annular slurry reactor, to evaluate its performance under different operating and design conditions. The reactor had two concentric cylinders with the inner one rotating at specified revolutions per minute. The reactor also had provisions for aerating the slurry present in the annular gap. The inner cylinder housed the UV-lamps. The effects of catalyst loading (0–8 g/L), inner cylinder rotation speed (0–50 rpm), annular gap-width (7.5, 17.5 and 32.5 mm), initial pollutant concentration (10–50 mg/L) and mode of illumination (continuous or periodic) were studied. Light intensity received by the slurry was measured using Actinometry. Depending on the catalyst loading, annular gap-width and number of illuminated lamps the intensity values ranged from 0.58×10^?4 to 6.4×10^?4 Einsteins/L min. Under well mixed conditions, the reactor performance was found to increase with increase in catalyst loading. At low/medium annular gap width configurations, agitation induced by continuous aeration was found to provide sufficient mixing even when the inner cylinder was stationary. Rotation of the inner cylinder was required only in the high gap width configuration at high catalyst loadings. Scale-up of the reactor was investigated by increasing the gap-width of the annulus and hence increasing the quantity of feed processed. Controlled periodic illumination created by Taylor vortices did not show any improved performance over the regular continuous illumination. Modeling of reaction kinetics was investigated with different approaches and their efficacy in fitting the concentration–time trends of both the primary pollutant and the intermediates are discussed.     

Highly sensitive electrochemical determination of nitric oxide using fused spherical gold nanoparticles modified ITO electrode

This paper describes the highly sensitive electrochemical determination of nitric oxide (NO) using the fused spherical gold nanoparticles (FAuNPs) modified ITO electrode. The FAuNPs were self-assembled on a (3-mercaptopropyl)-trimethoxysilane (MPTS) sol-gel film, which was preassembled on ITO electrode. The attachment of FAuNPs on MPTS sol-gel film was confirmed by UV-vis absorption spectroscopy, atomic force microscopy (AFM) and cyclic voltammetry (CV). The AFM image shows that the AuNPs retain their fused morphology after immobilized on MPTS sol-gel film. The FAuNPs modified ITO electrode shows an excellent electrocatalytic activity towards the oxidation of NO. Using FAuNPs modified electrode, the detection of 12 nM NO was achieved for the first time by amperometry method. Further, the current response was increased linearly with increasing NO concentration in the range of 1.2 × 10⁻⁸ to 7 × 10⁻⁴ M and the detection limit was found to be 3.1 × 10⁻¹⁰ M (S/N = 3). The FAuNPs modified ITO electrode displays an excellent selectivity towards the determination of 12 nM NO even in the presence of 1000-fold excess common interfering agents.     

Development and Integration of Sub-hourly Rainfall–Runoff Modeling Capability Within a Watershed Model

Increasing urbanization changes runoff patterns to be flashy and instantaneous with decreased base flow. A model with the ability to simulate sub-daily rainfall–runoff processes and continuous simulation capability is required to realistically capture the long-term flow and water quality trends in watersheds that are experiencing urbanization. Soil and Water Assessment Tool (SWAT) has been widely used in hydrologic and nonpoint sources modeling. However, its subdaily modeling capability is limited to hourly flow simulation. This paper presents the development and testing of a sub-hourly rainfall–runoff model in SWAT. SWAT algorithms for infiltration, surface runoff, flow routing, impoundments, and lagging of surface runoff have been modified to allow flow simulations with a sub-hourly time interval as small as one minute. Evapotranspiration, soil water contents, base flow, and lateral flow are estimated on a daily basis and distributed equally for each time step. The sub-hourly routines were tested on a 1.9 km² watershed (70% undeveloped) near Lost Creek in Austin Texas USA. Sensitivity analysis shows that channel flow parameters are more sensitive in sub-hourly simulations (Δt = 15 min) while base flow parameters are more important in daily simulations (Δt = 1 day). A case study shows that the sub-hourly SWAT model reasonably reproduces stream flow hydrograph under multiple storm events. Calibrated stream flow for 1 year period with 15 min simulation (R ² = 0.93) shows better performance compared to daily simulation for the same period (R ² = 0.72). A statistical analysis shows that the improvement in the model performance with sub-hourly time interval is mostly due to the improvement in predicting high flows. The sub-hourly version of SWAT is a promising tool for hydrology and non-point source pollution assessment studies, although more development on water quality modeling is still needed.