Laser beam weld-metal microstructure in a yttrium modified directionally solidified Ni3Al-base alloy

The microstructure of laser beam weld-metal of an yttrium doped directionally solidified alloy IC 6A, with chemical composition Ni–16Al–8.5Mo–0.12B–0.05C–0.03Y (at.%) was studied. The dendritic microsegregation observed within the fusion zone indicated that dendrite cores were slightly depleted in molybdenum and aluminum and the interdendritic regions were also considerably enriched in yttrium. Severe cracking in the weld-metal was observed and was found to be closely associated with interdendritic eutectic-type microconstituents identified as consisting of γ, γ′ and Ni–Mo phases. An yttrium-rich phase (Ni₃Y) was observed in some interdendritic regions containing the eutectic γ, γ′ and Ni–Mo products. Their formation was discussed in relation to plausible microsegregation induced alteration of primary solidification path during cooling from welding temperatures.     

Changes in differently processed soya bean (Glycine max.) and lima bean (Phaseolus lunatus) with particular reference to their chemical composition and their mineral and some inherent anti-nutritional constituents

The effects of 3 processing techniques: cooking, roasting and autoclaving on the proximate chemical composition, the mineral content and some inherent toxic factors of soya and lima beans were investigated. The processing techniques generally reduced the crude fibre levels and enhanced the extractable fat in the soya and lima beans. The coefficients of variability for crude fibre and ether extract due to the processing techniques of soya and lima beans were 20.9%, 16.0% and 22.3%, 38.1%, respectively. In parallel with decreased ash content in the cooked bean samples, there was a decrease in the K, Mg, Na and P levels relative to the raw bean and also relative to the other processing techniques. Mineral contents of the autoclaved bean samples were generally similar to those of the raw (unprocessed) samples. Under the processing conditions, roasting caused the highest reduction in thioglucoside content (59%) in soya bean while cooking caused the highest reduction in lima bean (78%). Trypsin inhibitor activity (TIA) ranged between 0.59 mg/g sample in the cooked soya bean and 11.6 mg/g sample in the raw bean while the corresponding values for lima bean ranged between 0.59 and 6.3 mg/g sample. Cooking and roasting caused over 90% reduction of TIA, while autoclaving caused 64-69% reduction in both bean samples. Under the assay conditions, haemagglutinating activity was not detected in the cooked and autoclaved soya and lima beans. The need to prevent both functional and nutritional damage to food proteins and other nutrients, resulting from excessive heating, was discussed.     

Dynamic analysis of LLCC parallel resonant converter under pulse-width modulation control

Contents The large and small signal dynamic analysis of LLCC-type parallel resonant converter operating in continous-conduction mode under fixed frequency, variable duty-ratio (pulse-width modulation) control is presented in this paper. The nonlinear and small-signal equations of the converter including the supply and output rectifiers are derived. The influence of the converter operation on the supply input power factor and how the input rectifier affects the small-signal dynamics of the converter are discussed.

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Dynamische Analyse von LLCC Parallel-Resonanz-Umrichtern bei Puls-Weiten-Modulation

Übersicht Die dynamische Groß- und Kleinsignalanalyse von LLCC Parallel-Resonanz-Umrichtern im nicht lückenden Betrieb bei fester Frequenz und Puls-Weiten-Modulation wird dargestellt. Die Gleichungen für nichtlineares und Kleinsignalverhalten des Umrichters unter Berücksichtigung der Eingangs- und Ausgangsgleichrichter werden abgeleitet. Der Einfluß des Umrichters auf den Leistungsfaktor am Eingang und die Wirkung des Eingangsgleichrichters auf die Kleinsignaldynamik des Umrichters werden diskutiert.

     

Influence of Solid-State Diffusion during Equilibration on Microstructure and Fatigue Life of Superalloy Wide-Gap Brazements

The influence of solid-state diffusion-controlled solute-loss into additive powder particles (APPs), as determined by particles size, during the equilibration stage of wide-gap brazing, on microstructure and fatigue behavior of a brazed aerospace superalloy was studied. The results, which experimentally confirm previously reported numerical model simulation results, show that, in order to avoid degradation of fatigue life of wide-gap brazement, adequate solute-loss into the APPs, which is necessary to prevent their complete melting, but has not been generally considered, is imperative.     

An analysis of single-phase self-excited induction generators:model development and steady-state calculations

The modeling and steady-state performance of single-phase induction generators based on the principles of harmonic balance is set forth in this paper. Magnetizing flux linkage saturation and flux dependent core loss resistances are included. Experimental results are provided to justify the analytical approach and steady-state calculations     

Analysis of Rain-Induced Attenuation at Ku-V Band Using Gamma Drop Size Distribution Model Over a Tropical Region

Wireless Personal Communications - In this paper, modeling of rain drop size distribution (DSD) and analysis of rain-induced attenuation are analyzed based on Gamma DSD model in a tropical...     

Remediation of oil spill polluted water from Niger Delta Nigeria by sorption onto ammonium sulfate modified Dialium guineense seed husk

The abstraction of crude oil molecules from aqueous solution (produced water) and from real petroleum polluted water (collected from River State, Nigeria) by Dialium guineense Seed Husk (DGSH) and its ammonium sulfate functionalized form (AS-DGSH) was studied using a batch technique. The sorbents were characterized using Fourier transform infrared (FTIR), BET surface area analysis and the Scanning electron microscopy (SEM). Crude oil characterization revealed a light crude oil based on the API gravity of 35.6⁰. The Langmuir and Freundlich models gave good fits for crude oil sorption on DGSH and AS-DGSH respectively. The sorbents were found to remove over 50% of crude oil from the real polluted water at the natural pH of 6.1 and showed increase in removal with increase in sorbent dose. The potential of DGSH and its ammonium sulfate modified derivative as effective low cost sorbents for oil spill treatment was established.     

Effect of thickness: a case study of electrodeposited CdS in CdS/CdTe based photovoltaic devices

The effect of electrodeposition technique on CdS thickness incorporated in CdS/CdTe-based solar cell has been investigated using all-electrodeposited g/FTO/n-CdS/n-CdTe/p-CdTe multilayer device configuration. The optical, morphological and structural properties of the electroplated CdS were investigated for CdS thicknesses between 50 and 200 nm. The observed CdS bandgap ranges between 2.42 and 2.46 eV. The morphological analysis shows full coverage of underlying g/FTO substrate for all CdS thicknesses except for the 50 nm which shows the presence of gap in-between grains. The structural analysis shows a preferred orientation of H(101) for all the CdS thicknesses except the 50 nm thick CdS which shows either a weak crystallinity or an amorphous nature. The fabricated solar cell shows a maximum conversion efficiency of ~11 % using CdS thickness ranging between 100 and 150 nm. These results show that although low CdS thickness is desirable for photovoltaic application, the effect of nucleation mechanism of deposition technique should be taken into consideration.