Optimal approximation of asymmetric type fractional-order bandpass Butterworth filter using decomposition technique

In this letter, the optimal rational approximation of fractional-order bandpass Butterworth filter (FOBBF) is presented. The transfer function of the FOBBF is decomposed into a multiplication of first-order and second-order terms. As a result, the design stability conditions can be easily satisfied using only the variable boundary constraints. The proposed technique generalizes the symmetric fractional-order roll-off characteristic as only a special case of the asymmetric one. Several examples are presented to validate the modeling efficacy.     

The changes of chemical composition of microencapsulated roselle (Hibiscus sabdariffa L.) seed oil by co-extrusion during accelerated storage

Roselle seed oil (RSO) is an underutilised seed oil, which is having beneficial properties to humans. Microencapsulation of vegetables and seed oil is an alternative to preserve these properties and deliver them to the human diet. In this study, microencapsulation of RSO was performed using co-extrusion technology and 1.5% w/w sodium alginate solution with 1.5% w/w high methoxyl pectin as the wall materials. Results showed that the microencapsulation efficiency was high (95.68 ± 1.95%) and the microencapsulation indeed preserved the content of unsaturated fatty acids, phytosterols, and tocopherols. During an accelerated storage condition at 65 °C for 24 days, most of these properties remained high for the first six storage days, including tocopherol which preserved high γ-tocopherol. Worth noting that the microencapsulated RSO (MRSO) was particularly effective in preserving the total unsaturated fatty acids (especially C18:1 and C18:2), even during the 24th day of storage. The total unsaturated fatty acids retained by MRSO were significantly (P < 0.05) higher (70 ± 0.4%) than the RSO (65.6 ± 1.6%). In short, microencapsulation was effective in preserving the RSO properties.     

Surface-tailoring chlorine resistant materials and strategies for polyamide thin film composite reverse osmosis membranes

Polyamide thin film composite membranes have dominated current reverse osmosis market on account of their excellent separation performances compared to the integrally skinned counterparts. Despite their very promising separation performance, chlorine-induced degradation resulted from the susceptibility of polyamide toward chlorine attack has been regarded as the Achilles’s heel of polyamide thin film composite. The free chlorine species present during chlorine treatment can impair membrane performance through chlorination and depolymerization of the polyamide selective layer. From material point of view, a chemically stable membrane is crucial for the sustainable application of membrane separation process as it warrants a longer membrane lifespan and reduces the cost involved in membrane replacement. Various strategies, particularly those involved membrane material optimization and surface modifications, have been established to address this issue. This review discusses membrane degradation by free chlorine attack and its correlation with the surface chemistry of polyamide. The advancement in the development of chlorine resistant polyamide thin film composite membranes is reviewed based on the state-of-the-art surface modifications and tailoring approaches which include the in situ and post-fabrication membrane modifications using a broad range of functional materials. The challenges and future directions in this field are also highlighted.     

Analysis of Fatty Acid and Lignan Composition of Indian Germplasm of Sesame to Evaluate Their Nutritional Merits

An attempt was made to individually analyze a germplasm collection of 54 indigenous Indian sesame cultivars for fatty acid and lignan composition of their seed oil by gas chromatography and high performance liquid chromatography, respectively. The entries varied in their fatty acid and lignan composition. The mean percentage contents of palmitic, stearic, oleic, linoleic and α‐linolenic acids ranged between 10–22, 5–10, 38–50, 18–43 and less than 1 whereas sesamol, sesamin and sesamolin scored between 3–37, 27–67, 20–59 of the total percentage of lignan, respectively. The highest percentage of α‐linolenic acid (ALA) was obtained in Var‐9 (1.3 % of the total fatty acids). Among the lignans, high sesamin content is considered to be significant, particularly in terms of long shelf life and nutraceutical value of sesame seed oil. The study has broadened our understanding related to differential biochemical composition of the rich sesame germplasms, thereby providing us with a useful groundwork for identifying potential targets and suitable cultivars for genetic engineering approaches to be undertaken in order to improve the nutritional quality of sesame oil, which in turn would be beneficial towards human health.     

Electrical,mechanical, and thermal properties of exfoliated graphite/phenolic resin composite bipolar plate for polymer electrolyte membrane fuel cell

Exfoliated graphite (EG) was synthesized from natural flake graphite by acid treatment followed by microwave irradiation. A maximum expanded volume of 560 mL/g was achieved for this exfoliation of graphite. EG/phenolic resin composite bipolar plates for polymer electrolyte membrane fuel cell were fabricated with a high loading of EG by compression molding. The composites possess low density, high electrical conductivity, high thermal stability, and high compressive strength. The composite bipolar plates were also characterized by X‐ray diffraction, scanning electron microscopy, thermogravimetric analysis, and so on. The composite prepared with 50 wt% of EG has shown the desired properties for bipolar plate as per the US Department of Energy (DOE‐2015) targets. As a result, the EG–resin composites can be used as bipolar plates for polymer electrolyte membrane fuel cell applications. POLYM. ENG. SCI., 55:917–923, 2015. © 2014 Society of Plastics Engineers     

Sinterability of Forsterite Prepared via Solid‐State Reaction

In this work, the sinterability of forsterite powder synthesized via solid‐state reaction was investigated. X‐ray diffraction (XRD) analyses indicate that the synthesized powder possessed peaks that correspond to stoichiometric forsterite. Scanning electron micrographs revealed that the powders were formed agglomerates, which were made up of loosely packed fine particles. Subsequently, the forsterite powders were cold isostatically pressed into a disk shape under 200 MPa and sintered in air at temperature ranging from 1200°C to 1500°C (interval of 50°C) with ramp rate of 10°C/min and dwelling time of 2 h. The sinterability of each sintered samples was examined in terms of phase stability, relative density, Vickers hardness, fracture toughness, and microstructural examination. XRD examination on all the sintered samples exhibited pure forsterite, in which the generated peaks were found to be in a good agreement with JCPDS card no. 34‐0189. The densification of forsterite progressed to reach a maximum relative density of ~91% at 1500°C. This study also revealed that high‐strength forsterite ceramic can be synthesized via solid‐state reaction as forsterite attained favorable mechanical properties, having fracture toughness of 4.88 MPam^1/2 and hardness of 7.11 GPa at 1400°C.     

Soft computing‐based approach for optimal design of on‐chip comparator and folded‐cascode op‐amp using colliding bodies optimization

This paper presents an efficient approach for the optimal designs of two analog circuits, namely complementary metal oxide semiconductor) two‐stage comparator with p‐channel metal oxide semiconductor input driver and n‐channel input and folded‐cascode operational amplifier using a recently proposed meta‐heuristic‐based optimization algorithm named as colliding bodies optimization (CBO). It is a multi‐agent algorithm that does not depend upon any internal control parameter, making the algorithm extremely simple. The main objective of this paper is to optimize the metal oxide semiconductor (MOS) transistors' sizes using CBO in order to reduce the areas occupied by the circuits and to get better performance parameters of the circuits. Simulation Program with Integrated Circuit Emphasis simulation has been carried out by using the optimal values of MOS transistors' sizes and other design parameters to validate that CBO‐based design is satisfying the desired specifications. Simulation results demonstrate that the design specifications are closely met and the required functionalities are achieved. The simulation results also confirm that the CBO‐based approach is superior to the other algorithms in terms of MOS area and performance parameters like gain, power dissipation, etc., for the examples considered. Copyright © 2016 John Wiley & Sons, Ltd.     

Synergistic Effects of Carbon Fillers of Phenolic Resin Based Composite Bipolar Plates on the Performance of PEM Fuel Cell

The most essential and costly component of polymer electrolyte membrane fuel cells is the bipolar plate. The production of suitable composite bipolar plates for polymer electrolyte membrane fuel cell with good mechanical properties and high electrical conductivity is scientifically and technically very challenging. This paper reports the development of composite bipolar plates using exfoliated graphite, carbon black, and graphite powder in resole‐typed phenol formaldehyde. The exfoliated graphite with maximum exfoliated volume of 570 ± 10 mL g⁻¹ used in this study was prepared by microwave irradiation of chemically intercalated natural flake graphite in a few minutes. The composite plates were prepared by varying exfoliated graphite content from 10 to 35 wt.% in phenolic resin along with fixed weight percentage of carbon black (5 wt.%) and graphite powder (3 wt.%) by compression molding. The composite plates with filler weight percentage of 35/5/3/exfoliated graphite/carbon black/graphite powder offer in‐plane and trough‐plane electrical conductivities of 374.42 and 97.32 S cm⁻¹, bulk density 1.58 g cm⁻³, compressive strength 70.43 MPa, flexural strength 61.82 MPa, storage modulus 10.25 GPa, microhardness 73.23 HV and water absorption 0.22%. Further, I–V characteristics notify that exfoliated graphite/carbon black/graphite powder/resin composite bipolar plates in unit fuel cell shows better cell performance compared exfoliated graphite/resin composite bipolar plates. The composite plates own desired mechanical properties with low bulk density, high electrical conductivity, and good thermal stability as per the U.S. department of energy targets at low filler concentration and can be used as bipolar plates for proton exchange membrane fuel cells.