Application of ameliorated Harris Hawks optimizer for designing of low-power signed floating-point MAC architecture

Neural Computing and Applications - Recently established Harris Hawks optimization (HHO) has natural behaviour for finding an optimum solution in global search space without getting trapped in...     

Analysis of variance in spectroscopic imaging data from human tissues

The analysis of cell types and disease using Fourier transform infrared (FT-IR) spectroscopic imaging is promising. The approach lacks an appreciation of the limits of performance for the technology, however, which limits both researcher efforts in improving the approach and acceptance by practitioners. One factor limiting performance is the variance in data arising from biological diversity, measurement noise or from other sources. Here we identify the sources of variation by first employing a high throughout sampling platform of tissue microarrays (TMAs) to record a sufficiently large and diverse set data. Next, a comprehensive set of analysis of variance (ANOVA) models is employed to analyze the data. Estimating the portions of explained variation, we quantify the primary sources of variation, find the most discriminating spectral metrics, and recognize the aspects of the technology to improve. The study provides a framework for the development of protocols for clinical translation and provides guidelines to design statistically valid studies in the spectroscopic analysis of tissue.     

Highly stable and active Ni-mesoporous alumina catalysts for dry reforming of methane

Nanostructured Ni-incorporated mesoporous alumina (MAl) materials with different Ni loading (7, 10 and 15 wt %) were prepared by a template assisted hydrothermal synthesis method and tested as catalysts for CO₂ reforming of methane under different conditions (nickel loading, gas hourly space velocity (GHSV), reaction temperature and time-on-stream (TOS)). The most active catalyst tested (Ni(10 wt%)-MAl) showed a very high stability over 200 h compared to a Ni(10 wt%)/γ-Al₂O₃ prepared using a co-precipitation method which had a significant loss in activity after only ∼4 h of testing. The high stability of the Ni-MAl materials prepared by the template assisted method was due to the Ni nanoparticles in these catalysts being highly stable towards migration/sintering under the reaction conditions used (800 °C, 52,000 mL h⁻¹ g⁻¹). The low susceptibility of the Ni nanoparticles in these catalysts to migration/sintering was most likely due to a strong Ni-support interaction and/or active metal particles being confined to the mesoporous channels of the support. The Ni-MAl catalysts also had significantly lower amounts of carbon deposited compared to the catalyst prepared using the co-precipitation method.     

Influence of Texture on Mechanical Behavior of Friction-Stir-Processed Magnesium Alloy

Friction stir processing (FSP) improves the mechanical properties of metallic materials. In this study, a magnesium alloy AZ31B was friction stir processed by using single and multiple pass. The friction-stir-processed magnesium alloy exhibits higher tensile strength and ductility in the transverse direction (TD) compared to the longitudinal direction (LD). Both single pass and multiple (two) pass friction-stir-processed material show similar anisotropy in tensile properties, but the multiple pass friction-stir-processed material shows fine-grained microstructure with higher tensile strength and ductility. The tensile anisotropy in the friction-stir-processed AZ31B originated from the textured microstructure that evolved during FSP.     

Selection of optimal feed flow sequence for a multiple effect evaporator system

A nonlinear model is developed for a SEFFFE system employed for concentrating weak black liquor in an Indian Kraft Paper Mill. The system incorporates different operating strategies such as condensate-, feed- and product-flashing, and steam- and feed-splitting. This model is capable of simulating a MEE system by accounting variations in τ, U, Q_loss, physico-thermal properties of the liquor, F and operating strategies.The developed model is used to analyze six different F including backward as well as mixed flow sequences. For these F, the effects of variations of input parameters, T₀ and F, on output parameters such as SC and SE have been studied to select the optimal F for the complete range of operating parameters. Thus, this model is used as a screening tool for the selection of an optimal F amongst the different F.An advantage of the present model is that a F is represented using an input Boolean matrix and to change the F this input matrix needs to be changed rather than modifying the complete set of model equations for each F. It is found that for the SEFFFE system, backward feed flow sequence is the best as far as SE is concerned.     

Effect of weather conditions on concentration of calcium,manganese, zinc,copper and iron in green tea (Camellia sinensis (L) O kuntze) leaves of North-Western India

Variations of calcium, manganese, zinc, copper and iron contents in green tea leaves due to weather conditions were studied for three cropping seasons with a view to provide information on nutritional requirements to boost productivity. The concentrations of these micronutrients were related to the uptake capability of tea plants as affected by different weather parameters. High temperature and high atmospheric evaporative demand assisted calcium uptake whereas high humidity and high rainfall reduced it. Low temperature and high humidity reduced manganese uptake. High weekly evaporation, weekly relative humidity and accumulated rainfall depressed the uptake of zinc, copper and iron in green tea shoots.     

Stereological characterization of crack path transitions in ceramic matrix composites

All ceramic composites involve a mismatch in physical properties the extent of which differs from one composite to another. Mismatch in thermal expansion (Δα) and elastic modulus (ΔE) is known to produce stresses that influence the path of a propagating crack. Thus, the relative effect of thermal and elastic mismatch on the crack path is expected to change with change in stress intensity. We propose that the crack path in ceramic composites should undergo a transition with the crack being strongly influenced by the thermal mismatch stresses at low stress intensity and elastic mismatch stresses at high stress intensities. Thus, a material in use under different applications each with its own loading conditions is expected to exhibit different crack propagation tendencies which may be reflected in the υ-K characteristics of the composite material. In the present work several model composites with different combinations of thermal and elastic mismatch have been considered. Cracks propagating at different sub-critical stress intensities (velocities) were generated by a novel indentation technique. Each indentation was performed at a constant displacement rate and a peak load. A range of displacement rates were used to produce cracks propagating at different velocities. The indentations were made using a Vickers indentor fitted in a universal mechanical testing machine. The crack paths in composites were quantified by stereological technique and the proposed theory was verified.     

Equal-gain diversity receiver performance in wireless channels

Performance analysis of equal-gain combining (EGC) diversity systems is notoriously difficult only more so given that the closed-form probability density function (PDF) of the EGC output is only available for dual-diversity combining in Rayleigh fading. A powerful frequency-domain approach is therefore developed in which the average error-rate integral is transformed into the frequency domain, using Parseval's theorem. Such a transformation eliminates the need for computing (or approximating) the EGC output PDF (which is unknown), but instead requires the knowledge of the corresponding characteristic function (which is readily available). The frequency-domain method also circumvents the need to perform multiple-fold convolution integral operations, usually encountered in the calculation of the PDF of the sum of the received signal amplitudes. We then derive integral expressions for the average symbol-error rate of an arbitrary two-dimensional signaling scheme, with EGC reception in Rayleigh, Rician, Nakagami-m (1960), and Nakagami-q fading channels. For practically important cases of second- and third-order diversity systems in Nakagami fading, both coherent and noncoherent detection methods for binary signaling are analyzed using the Appell hypergeometric function. A number of closed-form solutions are derived in which the results put forward by Zhang (see ibid., vol.45, p.270-73, 1997) are shown to be special cases.     

Implementation of the Decorrelating Receiver for Asynchronous DS-CDMA Systems over Multipath Fading Channels

This paper presents a decorrelating detector for DS-CDMAasynchronous systems over multipath fading channels. The decorrelatingreceiver applies the inverse correlation matrix of signature waveformsto detect the received signal. A procedure for finding such an inversematrix is developed. This procedure employs the reciprocal basis,derived from the basis of normalized user signatures, to cancelsimultaneously both the multiuser and the intersymbolinterference. The proposed multiuser detector operates over a finitedetection window, and the only restriction imposed on the set of signaturesis that the signatures must be independent at the receiver end. If the channelis slowly variant, the detectorcan be very efficient for high bit rate transmissions. Theoreticalbounds for the multiuser interference are obtained. Simulationresults, in which both binary and non-binary sequences are used,reveal that the behaviour of the detector approaches the single userbound when an adequate set of signatures is employed. The reducedcomplexity of this detector indicates that it could be a good candidatefor practical implementation.     

Processing and properties of nano‐ and macro‐hydroxyapatite/poly(ethylene‐co‐acrylic acid) composites

Hydroxyapatite (HAp)/poly(ethylene‐co‐acrylic acid) composites have been synthesized by a solution‐based method, using nanosized (n‐HAp) and coarse hydroxyapatite (c‐HAp) particles, respectively. X‐ray diffraction study has indicated the development of compressive and tensile stresses in composites because of the thermal expansion mismatch between the particles and polymer matrix. Fourier transform infrared absorption spectra and thermal analysis have showed the presence of strong interfacial bonding between the particles and polymer. The surface roughness and the homogeneous dispersion of HAp particles in the polymer matrix have been observed by scanning electron microscopy. A comparison in mechanical properties between composites prepared with n‐HAp and c‐HAp particles, respectively, has been studied. Nanosized particles contribute excellent improvement of mechanical properties of the composites rather than the coarse particles. The uniform dispersion of HAp particles, followed by the improvement in mechanical properties of the composite, provides a means of preparing HAp/polymer composites for low load‐bearing implant applications. POLYM. COMPOS., 27:633–641, 2006. © 2006 Society of Plastics Engineers