Copper recovery and simultaneous COD removal from copper phthalocyanine dye effluent using bipolar disc reactor

Electrochemical treatment of real acidic effluent of copper phthalocyanine dye manufacturing plant with a view to explore the feasibility of the simultaneous removal of copper and phthalocyanine using a bipolar disc electrochemical reactor has been investigated. Experiments were conducted in a bipolar capillary gap disc stack electrochemical reactor under batch recirculation mode. Electrodes were RuO₂ and IrO₂ coated on titanium as anode and titanium as cathode. Effects of current density, electrolysis time and effluent flow rate on copper recovery and simultaneous COD removal and energy consumption were critically examined. The current density of 2.5 A dm⁻² and flow rate of 20 L h⁻¹ achieved 91.1% COD removal and 90.1% copper recovery with the energy consumption of 50.86 kWh kg⁻¹ for COD removal and simultaneous recovery of copper in a bipolar disc stack reactor.     

CuInxGa1−xSe2 thin films prepared by electron beam evaporation

CuIn_xGa_1−xSe₂ bulk compound of three different compositions x=0.75, 0.80 and 0.85 have been prepared using individual elements of copper, indium, gallium and selenium. Thin films of CuIn_xGa_1−xSe₂ have been deposited using the prepared bulk by electron beam evaporation method. The structural studies carried on the deposited films revealed that films annealed at 400 °C are crystalline in nature exhibiting chalcopyrite phase. The position of the (1 1 2) peak in the X-ray diffractogram corresponding to the chalcopyrite phase has been found to be dependent on the percentage of gallium in the films. The composition of the prepared bulk and thin films has been identified using energy dispersive X-ray analysis. The photoluminescence spectra of the CuIn_xGa_1−xSe₂ films exhibited sharp luminescence peaks corresponding to the band gap of the material.     

The effect of deterministic spatial variations in retrograde wellimplants on shallow trench isolation for sub-0.18 μm CMOS technology

The high energy retrograde well implants for sub-0.18 microns CMOS are done at a normal or near normal incidence to minimize the shadowing due to the thick photoresist edges. The endstation geometry in a high energy implanter results in an incident angle variation across the wafer, which causes strong spatial variations in the well profile and can negatively impact device performance. We show that the spatial variations can have significant impact on shallow trench isolation (STI), by causing in a deterministic pattern the failure of STI devices on a wafer. These spatial variations are important and need to be taken into consideration for STI design     

Quantification of Porosity in Ceramic Matrix Composites Using Thermography

Thermography is one of the Non-Destructive Evaluation methods used to qualitatively estimate the amount of porosity in as-manufactured ceramic matrix composite (CMC) parts. Through-transmission (TT) thermography allows for comparison of thermal diffusivity caused by differences in material density and porosity at different locations in the part. In this study, volume fraction of pores and its distribution in CMC samples containing different amounts of porosity was quantified using optical microscopy and X-ray computed tomography scans. TT thermography was done on the same specimens and images were analyzed to determine the distribution of thermal diffusivity. Comparison of porosity measurements and thermal diffusivity images shows an inverse correlation. A simple two-phase analytical model describing this relationship is derived for composites and its solution is shown to compare favorably with experimental data. In the absence of porosity data, the model can be used to estimate porosity directly from thermal diffusivity data.     

Room temperature multiferroic properties of BiFeO3–MnFe2O4 nanocomposites

The novel functionalities of multiferroic magneto-electric nanocomposites have spawned substantial scope for fast-paced memory devices and sensor applications. Following this, herein we report the development of nanocomposites with soft ferromagnetic MnFe₂O₄ and ferroelectric BiFeO₃ to fabricate a system with engineered multiferroic properties. A modified sol-gel route called Pechini method is demonstrated for the preparation of the (1-x) BiFeO₃-x MnFe₂O₄ (x = 10%, 30%, 50%, 70%) nanocomposites. The crystallographic phase, structure, and morphology are characterized by XRD, FESEM, and HRTEM. The accurate crystallite size and lattice strain are determined by Williamson-Hall plot method and a comparative study with Scherer's equation is carried out. TEM image evidences the interface between BiFeO₃ and MnFe₂O₄ nanoparticles in the composite. The room temperature magnetic response reveals the strong dependence of magnetic saturation, remanent magnetization, and coercivity of the nanocomposites on MnFe₂O₄ addition. The dielectric response and impedance analysis of the prepared nanocomposites are observed. The electrical performance of the composite is affected by grain, grain boundaries, and oxygen vacancies. The unsaturated P-E loops exhibit the leaky ferroelectric behavior for the nanocomposite. The intrinsic magnetoelectric coupling between ferroelectric BiFeO₃ and ferromagnetic MnFe₂O₄ has been determined by varying H_dc/H_ac and its maximum coupling coefficient (α) is found to be 25.39 mV/cmOe for 70% BiFeO₃ -30% MnFe₂O₄ nanocomposite. These distinctive and achievable characteristics of the nanocomposite would enable the designing of magnetic field sensors, spintronic devices, and multiferroic memory devices.     

A 1-V programmable DSP for wireless communications [CMOS]

In an effort to extend battery life, the manufacturers of portable consumer electronics are continually driving down the supply voltages of their systems. For example, next-generation cellular phones are expected to utilize a 1-V power supply for their digital component. To address this market, an energy-efficient, programmable digital signal processing (DSP) chip that operates from a 1-V supply has been designed, fabricated, and tested. The DSP features an instruction set and micro-architecture that are specifically targeted at wireless communication applications and that have been carefully optimized to minimize power consumption without sacrificing performance. The design utilizes a 0.35-μm dual-V_t technology with 0.25-μm minimum gate lengths that enables good performance at 1 V. Specifically, the chip dissipates 17 mW at 1 V, achieving 63-MHz operation with a power-performance metric of 0.21 mW/MHz     

Mixed convection heat transfer in porous media in the non-darcy regime

In this study mixed convection heat transfer in a homogeneous porous duct of square cross section in a horizontal orientation is examined. Results from a generalized Forchheimer model are compared with that from the Darcy model. The heat transfer rate and the flow behavior depend on the following parameters: Grashof number, Gr = Q'gβKa/kv², an axial flow pressure drop parameter, ζ = (aK/vμ)dp'/dz', an inertial parameter ξ = mK/a, appearing in the Forccheimer model and the Prandtl number, Pr = C_pμ/k. In the Darcy limit, ξ → 0, the role of the axial flow parameter, λ is reduced to a mere scale factor and the flow behavior is determined by a single parameter, λ = Gr · Pr. Both the Darcy and the Forchheimer models exhibit dual solutions and a hysteresis behavior over a certain range of Gr. Such parametric dependence can be used as an additional tool along with carefully designed experiments to determine the importance of inertial and Prandtl number effects on convective heat transfer in porous media.     

Simultaneous determination of size and wavelength-dependent refractive indices of thin-layered droplets from optical resonances

A technique for determining the size and wavelength-dependent refractive indices of a droplet coated with a thin layer is presented. The existence of a layer on the droplet is identified by a procedure that involves separate alignments of independently measured TE- and TM-mode resonances with computed homogeneous-sphere resonances. The procedure also yields the mode and the order numbers associated with the measured resonances. The observed resonances are then aligned with layered-sphere resonances of the same mode and order numbers to determine the core radius, layer thickness, and constants of core and shell dispersion formulas that minimize the difference between the observed and the calculated positions of resonances. The technique has been tested with synthetic data with various levels of random errors as well as with experimental data from two droplets under identical conditions. The results show that the core radius, layer thickness, and core and layer refractive indices can be determined with relative errors of 3.5 × 10(-4), 4.5 × 10(-2), 2.3 × 10(-4), and 4.4 × 10(-3), respectively, with the technique.     

Efficient Spectrum Handoff Using Hybrid Priority Queuing Model in Cognitive Radio Networks

Wireless Personal Communications - Cognitive radio networks can achieve high spectrum efficiency through dynamic spectrum allocation to the secondary users (SU) by way of using primary user (PU)...