hr-Adaptivity for nonconforming high-order meshes with the target matrix optimization paradigm

Engineering with Computers - We present an $$hr$$ -adaptivity framework for optimization of high-order meshes. This work extends the r-adaptivity method by Dobrev et al. (Comput Fluids, 2020),...     

A comparative study of wavelet families for EEG signal classification

Over the past two decades, wavelet theory has been used for the processing of biomedical signals for feature extraction, compression and de-noising applications. However the question as to which wavelet family is the most suitable for analysis of non-stationary bio-signals is still prevalent among researchers. This paper attempts to find the most useful wavelet function among the existing members of the wavelet families for electroencephalogram signal (EEG) analysis. The EEGs considered for this study belong to both normal as well as abnormal signals like epileptic EEG. Important features such as energy, entropy and standard deviation at different sub-bands were computed using the wavelet functions—Haar, Daubechies (orders 2-10), Coiflets (orders 1-10), and Biorthogonal (orders 1.1, 2.4, 3.5, and 4.4). Feature vectors were used to model and train the Probabilistic Neural Network (PNN) and the classification accuracies were evaluated for each case. The results obtained from PNN classifier were compared with Support Vector Machine (SVM) classifier. From the statistical analysis, it was found that Coiflets 1 is the most suitable candidate among the wavelet families considered in this study for accurate classification of the EEG signals. In this work, we have attempted to improve the computing efficiency as it selects the most suitable wavelet function that can be used for EEG signal processing efficiently and accurately with lesser computational time.     

An Evolutionary Normalization Algorithm for Signed Floating-Point Multiply-Accumulate Operation

In the era of digital signal processing, like graphics and computation systems, multiplication-accumulation is one of the prime operations. A MAC unit is a vital component of a digital system, like different Fast Fourier Transform (FFT) algorithms, convolution, image processing algorithms, etcetera. In the domain of digital signal processing, the use of normalization architecture is very vast. The main objective of using normalization is to perform comparison and shift operations. In this research paper, an evolutionary approach for designing an optimized normalization algorithm is proposed using basic logical blocks such as Multiplexer, Adder etc. The proposed normalization algorithm is further used in designing an 8 × 8 bit Signed Floating-Point Multiply-Accumulate (SFMAC) architecture. Since the SFMAC can accept an 8-bit significand and a 3-bit exponent, the input to thesaid architecture can be somewhere between −(7.96872)₁₀ to + (7.96872)₁₀. The proposed architecture is designed and implemented using the Cadence Virtuoso using 90 and 130 nm technologies (in Generic Process Design Kit (GPDK) and Taiwan Semiconductor Manufacturing Company (TSMC), respectively). To reduce the power consumption of the proposed normalization architecture, techniques such as “block enabling” and “clock gating” are used rigorously. According to the analysis done on Cadence, the proposed architecture uses the least amount of power compared to its current predecessors.     

Solubilization,micellar transition and biocidal assay of loaded antioxidants in Tetronic® 1304 micelles

The current study scrutinizes the solubilization behaviour of pharmaceutically active antioxidants, namely hydrocinnamic acid (HCA), cinnamic acid (CA) and phenyl propiolic acid (PPA), in the micelles of polyethylene oxide‐polypropylene oxide (PEO‐PPO) based star‐block copolymer: Tetronic® 1304 (T1304). A correlation between the molecular orbital energy levels of PEO‐PPO units of T1304 and the active parts of the antioxidants are well explained using a simulation study. The antioxidants modulate core–shell micelles of T1304 with enhanced solubilization dependent on their unsaturation and hydrophobicity, as depicted from UV–visible spectroscopy. Antioxidants as an additive induce micellization in 5% w/v T1304 thereby modulating the phase behaviour, as indicated by the decrease in the cloud point. The cloud point results are well complemented by steady state fluorescence spectroscopy findings, depicting a decrease in critical micelle temperature due to the solubilization of antioxidants into the T1304 micelles. A significant difference between the hydrodynamic diameter (D_h) of unloaded and loaded polymer micelles with antioxidants is observed from dynamic light scattering, ensuring the solubilization of the antioxidants in T1304 micelles. These results can apparently be attributed to the interaction and the charge induced by the antioxidants on non‐ionic T1304 micelles which increase the micellar size. Furthermore, the role of unsaturation and hydrophobicity of the employed antioxidants in 5% T1304 demonstrates the solution viscosity (η) change as a function of temperature. In addition, small‐angle neutron scattering depicts the shape transition (spherical to ellipsoidal to polymersomes) with temperature. The antioxidant loaded 5% T1304 micellar systems exhibit brilliant biocidal activity against the tested microbes, suggesting their antimicrobial application. © 2019 Society of Chemical Industry     

Modification of tung oil–based polyurethane foam by anhydrides and inorganic content through esterification process

In this study, we have reported the synthesis of modified polyol from tung oil. The synthesis involves three steps: first, conversion of tung oil to hydroxylated tung oil by hydroxylation; second, alcoholysis with triethanolamine; and finally, the esterification of polyester polyol when reacted with phthalic anhydride (PA) or maleic anhydride (MA). Boric acid is also introduced into the polyol by chemical modification, which enhances the thermal properties of polyurethane foam (PUF). PUF is formulated by the reaction between polyol and isocyanate. A systematic comparison of flame retardancy and mechanical and thermal properties of modified PUF has been examined. The structural properties of modified polyol were characterized by Fourier transform infrared spectroscopy, proton NMR spectroscopy, and gel permeation chromatography, while the thermal and mechanical properties of the formulated PUF were studied by scanning electron microscopy, limiting oxygen index, differential scanning calorimetry, Izod impact, and flexural and compression strength. Thus PUF prepared from modified polyol with a proper distribution of soft and hard segments possesses better mechanical and thermal properties. The PA‐modified foams show better properties compared to unmodified and MA‐modified foams due to the aromaticity and crosslinking behavior of PA. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45786.     

Global Optimization with Higher Order Inclusion Function Forms Part 1: A Combined Taylor-Bernstein Form

Recently, two versions of the so-called Taylor-Bernstein (TB) form having the property of higher order convergence were proposed in [5] and [10]. However, in many application problems, both these TB forms encounter difficulties in computing the range enclosures for some domain widths, due to excessive memory and/or time requirements. In this paper, we present a combined TB form that is more successful in computing the range enclosures as the domain shrinks from large to small widths. We test and compare the performance of the proposed form with those of the existing TB forms, the Taylor model of Berz et al. [1], and the simple natural inclusion function form. For the testing, we consider six benchmark examples with dimensions varying from 1 to 6. The results of the tests show that the proposed combined TB form is indeed more effective than the existing TB forms and the Taylor model, over the entire range of domain widths considered. This revised version was published online in June 2006 with corrections to the Cover Date.     

Solubilisation study of water‐insoluble dye in cationic single/dimeric surfactant micelles: effect of headgroup,non‐polar tail,and spacer chain in aqueous and salt solution

The solubilisation of hydrophobic azo dye Orange OT in aqueous/salt solution in several cationic surfactant micelles was studied using UV‐vis spectroscopy. An attempt was made to correlate dye solubilising strength with adsorption/micellar characteristics. In our experiments we determined the change in solubilisation of hydrophobic dye when added to an aqueous solution of oppositely charged quaternary‐salt‐based cationic surfactants (conventional and gemini) and remarked on the probable location of the solubilised dye in the surfactant micelle. Results highlight the onset of dye solubilisation around the critical micelle concentration of each surfactant, which is influenced by the non‐polar tail, spacer, and polar headgroup, while no dye could be solubilised at concentrations below the critical micelle concentration. Orange OT solubilised almost linearly with increase in surfactant concentration at and above the critical micelle concentration. The change in colour intensity of the dye (darker below the critical micelle concentration, lighter at and above the critical micelle concentration) could be attributed to dye–surfactant interactions. Further dye solubilisation was observed in the presence of salt.     

Dynamic economic load dispatch using hybrid swarm intelligence based harmony search algorithm

This paper presents the hybrid harmony search algorithm with swarm intelligence (HHS) to solve the dynamic economic load dispatch problem. Harmony Search (HS) is a recently developed derivative-free, meta-heuristic optimization algorithm, which draws inspiration from the musical process of searching for a perfect state of harmony. This work is an attempt to hybridize the HS algorithm with the powerful population based algorithm PSO for a better convergence of the proposed algorithm. The main aim of dynamic economic load dispatch problem is to find out the optimal generation schedule of the generators corresponding to the most economical operating point of the system over the considered timing horizon. The proposed algorithm also takes care of different constraints like power balance, ramp rate limits and generation limits by using penalty function method. Simulations were performed over various standard test systems with 5 units, 10 units and 30 units and a comparative study is carried out with other recently reported results. The findings affirmed the robustness and proficiency of the proposed methodology over other existing techniques.     

Formation and Growth of Micelles in Dilute Aqueous CTAB Solutions in the Presence of NaNO<Subscript>3</Subscript> and NaClO<Subscript>3</Subscript>

Self-assembly of cetyltrimethylammonium bromide (CTAB) in aqueous solution, in the presence of two inorganic salts viz, NaNO₃ and NaClO₃ was investigated by steady-state fluorescence, electrical conductance, surface tension, viscosity, dynamic light scattering (DLS) and cryogenic transmission microscopy (cryo-TEM). The counterions located at short enough distances to CTA⁺ micellar surface experience a very strong electrostatic attraction and thus become condensed. This counterion condensation plays a significant role in deciding the effective charge on the micelle, their screening interaction and structural transition of the micelles. In the present work, the probable mechanism of the salts' action in aqueous solution of CTAB is explained. The critical micelle concentration (CMC), area per molecule (Ų), micelle hydrodynamic diameter (D _h ), and aggregation number (N _agg) of CTAB micelles in the absence and presence of the salts are reported. The addition of both salts followed the lyotropic series and showed a remarkable decrease in CMC. A detailed investigation of the structural transitions from spherical to rod or even to entangled wormlike structures is presented from cryoTEM.     

ZnS-PANI nanocomposite with enhanced electrochemical performances for lithium-ion batteries

A simple two-step method of coprecipitation followed by polymerization successfully yielded ZnS-PANI nanocomposite. This composite was characterized using XRD, FTIR, SEM, BET, and XPS. The results indicate that the morphology of the ZnS-PANI nanocomposite possesses a uniform spherical shape. The ZnS-PANI electrode shows an excellent initial discharge capacity of 1182.1 mAh/g, a high discharge capacity of 693.5 mAh/g at a current rate of 0.1 °C after 500 cycles, good cycling stability, and an excellent rate capability of 673 mAh/g at 2.0 °C, when used as anode materials for lithium-ion batteries (LIBs). The excellent electrochemical performances make the nanosized ZnS-PANI nanocomposite a promising candidate for the LIBs.