A Convenient Synthesis of β‐Phenylselenocarbonyl Compounds by In‐TMSCl Promoted Cleavage of Diphenyl Diselenide and Subsequent Michael Addition

A simple and convenient procedure has been developed for the synthesis of β‐phenylselenocarbonyl compounds by a one‐pot reaction of diphenyl diselenide and α,β‐unsaturated ketones, aldehydes, esters and nitriles in the presence of indium metal‐trimethylsilyl chloride under sonication. Presumably, the In‐TMSCl reagent system reacts with diphenyl diselenide to form an intermediate, PhSeSiMe₃, which then undergoes Michael addition with the α,β‐unsaturated carbonyl compounds to produce the products.     

A Mixed Finite Element Method for the Biharmonic Problem Using Biorthogonal or Quasi-Biorthogonal Systems

We consider a finite element method based on biorthogonal or quasi-biorthogonal systems for the biharmonic problem. The method is based on the primal mixed finite element method due to Ciarlet and Raviart for the biharmonic equation. Using different finite element spaces for the stream function and vorticity, this approach leads to a formulation only based on the stream function. We prove optimal a priori estimates for both stream function and vorticity, and present numerical results to demonstrate the efficiency of the approach.     

Structural,thermal, mechanical and dynamic mechanical properties of cenosphere filled polypropylene composites

Polypropylene (PP)/cenosphere based composites were fabricated and characterized for their structural/morphological and mechanical properties such as tensile, flexural, impact and dynamic mechanical properties such as storage and loss moduli as a function of temperature. The morphological attributes were characterized by scanning electron microscopy (SEM) and wide-angle X-ray diffraction (WAXD) while the thermal characterizations were done by conducting differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA). The morphological investigations have revealed a uniformly distributed/dispersed state of the cenosphere in the bulk PP matrix of the composites. The WAXD/DSC studies have revealed a decrease in crystallinity of the composites with increase in cenosphere content. Dynamic mechanical analysis (DMA) revealed an enhancement in the energy dissipation ability of the composite with 10 wt.% of cenosphere and an increase in the storage modulus up to ∼30% in the composites relative to the soft PP-phase. The tensile modulus increased up to ∼43% accompanied by a nominal decrease in tensile strength while the strain at break remained largely unaffected. The impact strength of the composites marginally reduced compared to PP indicating a low-cost material-concept with maximized stiffness–toughness combination. The theoretical modeling of the tensile data revealed appreciable extent of phase-adhesion despite the cenospheres lack any surface modification indicating better extent of mechanical interlocking and surface-compatibility between polymer and filler. Fractured surface morphology indicated that the failure mode of the composites undergoes a switch-over from matrix-controlled shear deformation to filler-controlled quasi-brittle modes above a cenosphere loading of 10 wt.% in the composites.     

Hydrodynamic and heat transfer characteristics of a centrally heated cylindrical enclosure: CFD simulations and experimental measurements

Natural convection in enclosures is of importance in many engineering applications. The stratification arising out of natural convection may be desirable/undesirable depending on applications. In order to control the degree of stratification, understanding of flow pattern and temperature profiles is required. In the present work, transient natural convection in a cylindrical enclosure has been investigated for water with CFD simulations and flow visualization [using particle image velocimetry (PIV) and hot film anemometry (HFA)] over a wide range of parameters namely Rayleigh number (1.08 × 10¹¹ ≤ Ra ≤ 3.76 × 10¹³) and aspect ratio (1 ≤ H/R ≤ 2). The effect of various parameters like pressure, tube diameter and aspect ratio on the extent of stratification has been studied. PIV measurements have been performed to understand the transient flow behavior. Multiple thermocouples were used to measure the temperature profiles. CFD simulations have been performed using SST k–ω model and the results have been compared with the PIV measurements. The CFD simulations have been carried out for 2D axi-symmetric cases and the effect of boundary conditions (free-slip and no-slip) has been investigated. An excellent agreement was found between the CFD predictions and the experimental measurements of flow and temperature patterns. The extent of stratification has been quantified using dimensionless parameters like stratification number and stratification time. The kinetic energy profiles and kinetic energy dissipation profiles show that almost 75% of the enclosure is stratified (after different times depending on Ra number and the aspect ratio). The turbulence parameters were found to weaken with time in the stratified region and these predictions are corroborated with HFA measurements.     

Deployment of Wi‐Fi network as an emergency survival communication network in Wakkanai,Hokkaido

Networks must be safeguarded against disasters. From the network‐management viewpoint, safeguards should be considered during the network design phase. In this study, we surveyed the potential of establishing redundant Wi‐Fi networks in schools in the Soya region of Hokkaido to proactively create a bypass communication network that can be used if a natural disaster occurs. During emergency situations such as earthquakes, tsunamis, and floods, a traditional disaster response may not be able to provide adequate communication services to emergency‐management teams. To explore the potential of establishing an emergency survival communication network in Wakkanai, Hokkaido, we conducted a medium‐scale trace‐driven study of redundant networks to determine how to decrease the disaster risk. We set up wireless nodes at four network locations of different sizes, including an access link between the Wakkanai city office and Wakkanai Hokusei Gakuen University networks. Furthermore, we model the optimal redundant topology and discuss the simulation result. By proactively establishing a redundant wireless network as a detour emergency route using our approach, an organization can rapidly reduce disaster risk. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Autonomous Ex Novo Chemical Assembly with Blebbing and Division of Functional Polymer Vesicles from a “Homogeneous Mixture”

The chemical energy and radicals from an oscillating chemical reaction are used to synthesize a polymer vesicle from a homogeneous solution of monomeric units. Periodically formed radicals from the Belousov–Zhabotinsky (B–Z) reaction initiate radical polymerization between a polyethylene glycol based chain transfer agent (PEG‐CTA) and hydrophilic acrylonitrile monomers in water. The growth of a hydrophobic chain on the hydrophilic PEG chain induces self‐assembly of polymeric amphiphiles to form micrometer‐sized vesicles entrapping an active oscillating B–Z reaction. In our experimental conditions, the different chemical environments inside and outside the vesicles contribute to enlarge the area and diameter of the resulting self‐assembled vesicles and, in some cases, promote blebbing and division.     

Speed enhancement of a class of digital phase locked loops (DPLLs) by dynamic gain control technique

A dynamic gain modification algorithm of a class of digital phase locked loops (DPLLs) has been proposed. It has been shown analytically that the modified DPLL based on the proposed algorithm can be designed to have a faster transient response besides having steady-state response and frequency acquisition range same as that of a conventional DPLL. Numerical simulation results have been given to support the analytical predictions.     

Kinetic Modeling of Liquid Phase Oxidation of Cyclohexane

A kinetic model for the liquid phase oxidation (LPO) of cyclohexane has been derived using a reaction network based on a consistent free radical mechanism. It was demonstrated that on embedding this rate model within the overall model of a semi‐batch gas‐liquid reactor (SBR) one can predict the time variation of the dissolved oxygen concentration and the rate of oxygen absorption which compare fairly closely with some well regarded published experimental data. The model is distinguished by easy extendibility and modularity whereby it could be tailored to predict, in the context of a SBR, cyclohexane conversion and ketone‐alcohol (K‐A) product selectivity levels as observed in commercial plants and in the published data on pilot plant experimentation. The model is expected to be of use in the design and scale‐up of LPO reactors.     

Method to determine the optical properties of turbid media

A novel method to determine the optical properties, namely, absorption coefficient, scattering coefficient, and anisotropy factor of turbid solutions, single constituent or multiconstituent, is presented. Turbid solutions of milk, ink, and a mixture of both were illuminated by a laser beam and measurements were carried out in scattered light. Experimental results were matched to the corresponding results of Monte Carlo simulation to obtain the optical properties of the turbid media.     

Development of Refractory Material from Water Quenched Granulated Ferrochromium Slag

High temperature refractory materials of refractoriness above 1665°C having refractory phases such as forsterite (Mg₂SiO₄), periclase (MgO) and spinel can be developed from the water granulated spongy ferrochromium slag granules (90% particle) of size below 3100 micron by MgO enrichment. MgO enrichment in ferrochrome slag can be achieved by a method comprises of grinding of granulated ferrochrome slag in presence of magnesite raw material followed by compaction and sintering. The ratio of MgO/SiO₂ > 2.2 and MgO/(Al₂O₃ + Cr₂O₃) > 1.71 in the final composition ensures the refractoriness above 1665°C.