Nitroglycerine (NG) Migration to Various Unsaturated Polyesters and Chloropolyesters Used for Inhibition of Rocket Propellants

The kinetics of NG migration has been studied for two groups of resins—Group I: PR-3, FUP-9 and EP-4 and Group II: PAP-1, CPAP-1 and CPAP-2. These unsaturated polyesters and chloropolyesters have been characterized for tensile strength (TS), %-elongation and crosslink density. Further, diffusion coefficient (D), NG migration at infinite time (M_∞) and concentration profiles have also been determined. The data generated on TS, crosslink density, D and M_∞ corroborate the fact that as the crosslink density increases, D as well as M_∞ decrease.     

Algebraic pruning: a fast technique for curve and surface intersection

Computing the intersection of parametric and algebraic curves and surfaces is a fundamental problem in computer graphics and geometric modeling. This problem has been extensively studied in the literature and different techniques based on subdivision, interval analysis and algebraic formulation are known. For low degree curves and surfaces algebraic methods are considered to be the fastest, whereas techniques based on subdivision and Bézier clipping perform better for higher degree intersections. In this paper, we introduce a new technique of algebraic pruning based on the algebraic approaches and eigenvalue formulation of the problem. The resulting algorithm corresponds to computing only selected eigenvalues in the domain of intersection. This is based on matrix formulation of the intersection problem, power iterations and geometric properties of Bézier curves and surfaces. The algorithm prunes the domain and converges to the solutions rapidly. It has been applied to intersection of parametric and algebraic curves, ray tracing and curve-surface intersections. The resulting algorithm compares favorably with earlier methods in terms of performance and accuracy.     

Saturated Sterols (Stanols) in Unhydrogenated and Hydrogenated Edible Vegetable Oils and in Cereal Lipids*

The content of saturated sterols (stanols) was investigated in a small number of samples of hydrogenated fats and oils, and in the ‘free’ and ‘bound’ lipids of various samples of cereals. The sterols, after saponification of the total lipids, were analysed as trimethylsilyl derivatives by GC and identified by GC–MS. Among the hydrogenated fats and oils, coconut oil contained the largest amounts of sitostanol followed by soybean oil (c 80 and 20 g kg⁻¹ of total unsaponifiables, respectively). No sitostanol could be detected in hydrogenated palm oil under the present analytical conditions. Both ‘free’ and ‘bound’ lipids in various samples of wheat, except for wheat germ, contained c 70–120 g kg⁻¹ campestanol and 100–150 g kg⁻¹ sitostanol in total unsaponifiables. In lipids of oats and barley, no campestanol or sitostanol could be detected. Rye total lipids contained 60–90 g kg⁻¹ of campestanol and 100–150 g kg⁻¹ of sitostanol of total unsaponifiables in ‘free’ and ‘bound’ lipids, respectively.     

Thermally stimulated depolarization currents in poly(2,6-dimethyl-1,4-phenylene oxide) films

Electrical properties of poly(2,6- dimethyl-1,4-phenylene oxide) (PPO) have been studied by measuring thermally stimulated discharge currents. Depolarization behavior of poled PPO film exhibits temperature- and time-dependent single relaxation around 468 K which is attributed to dipole reorientation. The peak maxima, however, shifts from 468 K to 484 K with increasing poling temperature. This indicates that the peak has a distribution of relaxation times. The polarization in semicrystalline PPO is found to decay slowly, indicating that the overall dipoles are more stable in comparison to amorphous PPO; hence, crystalline PPO forms comparatively stable electrets. © 1996 John Wiley & Sons, Inc.     

Entropy and improved k-nearest neighbor search based under-sampling (ENU) method to handle class overlap in imbalanced datasets

Many real-world application datasets such as medical diagnostics, fraud detection, biological classification, risk analysis and so forth are facing class imbalance and overlapping problems. It seriously affects the learning of the classification model on these datasets because minority instances are not visible to the learner in the overlapped region and the performance of learners is biased towards the majority. Undersampling-based methods are the most commonly used techniques to handle the above-mentioned problems. The major problem with these methods is excessive elimination and information loss, that is, unable to retain potential informative majority instances. We propose a novel entropy and neighborhood-based undersampling (ENU) that removed only those majority instances from the overlapped region which are having less informativeness (entropy) score than the threshold entropy. Most of such existing methods improved sensitivity scores significantly but not in many other performance contexts. ENU first computes entropy and threshold score for majority instances and, a local density-based improved KNN search is used to identify overlapped majority instances. To tackle the problem effectively ENU defined four improved KNN-based procedures (ENUB, ENUT, ENUC, and ENUR) for effective undersampling. ENU outperformed in sensitivity, G-mean, and F1-score average ranking with reduced information loss as compared to the existing state-of-the-art methods.     

SO-CPP: Sailfish optimization-based controller placement in IoT-enabled software-defined wireless sensor networks

One of the expanding network topologies that is frequently utilized to improve network development by successfully separating the control plane and data plane is software-defined networking (SDN). In order to function inside complex sensor networks, the SDWSN system frequently relies on centralized controller logic that pulls global network information. In wireless sensor networks (WSNs), using several SDN controllers is known as a promising strategy due to reliability and performance considerations. However, using numerous controllers increases the synchronization overhead between the controllers. Consequently, it is a difficult research challenge to discover the best placement of SDN controllers to enhance the performance of a WSN, subject to the maximum number of controllers calculated based on the synchronization overhead. This research introduces a novel technique to overcome the controller placement problem (CPP) by optimizing multi-constraints within the sensor networks. For selecting the optimal controllers and placing them in an optimal location, a novel sailfish optimization (SO) strategy is introduced that can enhance the search space and maintain optimal global values throughout the iteration. Then, node clustering is performed using the fuzzy-C-means (FCM) clustering technique, which can reduce energy consumption and path delay within the network. The overall latency obtained by the proposed method is about 0.51 and 0.56 ms, and a total run time of 4 ms for both single sink and multi-sink, respectively. The proposed method is implemented in the MATLAB platform, and different performance metrics are analyzed and compared with existing techniques.     

Air bubble migration through a cast solution of poly(methyl methacrylate)

Transport of air (with solvent vapor) bubbles that sometimes appear in a polymer/solvent liquid are followed in the process of solvent casting the polymer. The concentration profile of the solvent in the developing casting is found to be the primary controller of bubble rise velocity. This velocity dependence on concentration is developed through experiment over the range of conditions in the casting [∼90 to 0% methylene chloride in poly(methyl methacrylate), molecular weight 300,000, and Tg 110°C]. Assumptions of quasi steady-state and penetration type theories are used to generate this simplest model, qualitatively (and semi-quantitatively) correct in predicting the skin layer/bubble layer/bulk layer structure in solid polymer pieces produced by the solvent casting process.     

Recent advancements in condensers to enhance the performance of solar still: A review

Pure drinking water sources are continuously decreasing day by day in the world and in contrast requirement is continuously increasing. Solar still is a device, which converts the saline water into pure form at a lower cost and is useful in the remote areas. But its less productivity and low efficiency is a significant issue to use it as potable water provider. Solar still productivity can be increased by using flat plate collectors, fins, evacuated tubes, different absorbing, and nanomaterials, but the major problem on its productivity is heat loss from glass cover to the ambient. Condenser reduces the temperature of the water vapor and maintain the condensation to enhance the productivity. This review shows different modification in the design of condenser attached with solar still to enhance the yield. At last the future work on the condenser is also discussed here.     

Some quality characteristics of solar-dried cocoa beans in St Lucia

A field comparison of solar drying and open-air sun-drying of cocoa (Theobroma cocoa L) beans was carried out in St Lucia. Four methods of drying (indirect solar drier, direct solar drier, open air/perforated steel surface and open air/non-perforated wooden surface) were examined at three loading rates: 13·7, 26·9 and 40·4 kg m⁻². Beans from the open air had a higher incidence of external mould and poorer external appearance, though differences were minor. Beans dried at the lower rate of 13 kg m⁻² showed the best colour, but the highest titratable acidity. Conversely, beans dried at the higher loading rate of 40·4 kg m⁻² showed significantly lower titratable acidity, but poorer colour. Differences in cut-test score, colour, pH and titratable acidity between the open air and closed driers were small or not significant. While not significant, the indirect drier did show the highest cut-test score and the direct drier the poorest. Beans from the indirect drier were darker and more purple, while those from the direct drier were lighter coloured and less purple. The beans from the direct drier, dried to 6% moisture (WB) were, though not significantly so, more brittle and higher in titratable acidity than those from either the open air or indirect drier. Overall the beans from the indirect drier showed the highest quality and those from the direct drier the poorest. Whether the modest improvement of the indirect drier over the open air driers is sufficient to warrant investment in such a drier is unclear. © 1998 SCI.     

Green Synthesis of Zinc Oxide Nanoparticles (ZnO NPs) for Effective Degradation of Dye,Polyethylene and Antibacterial Performance in Waste Water Treatment

At present, there is a vital need for river water purification by developing new approaches to eliminate bacterial biofilms, textile dyes, and Low-Density Polyethylene (LDPE) plastics that pose severe threats to human and environmental health. The current work put forward the construction of an eco-friendly green strategy to synthesize zinc oxide nanoparticles (ZnO NPs) using areca nut (Areca catechu) extract and their application to tackle the challenges in water purification. Prepared biogenic NPs were characterized by X-ray diffraction analysis (XRD), Fourier Transform Infra-Red (FT-IR), Energy Diffraction Spectroscopy (EDS), Scanning Electronic Microscopy (SEM), Transmission Electron Microscopy (TEM) analysis, confirmed the spherical shape in 20 nm and UV–vis spectroscopy. The characteristic absorption band exhibited at 326 nm confirmed the formation of ZnO NPs using UV–vis spectroscopy. Among all the tested bacterial pathogens, the E. coli at 50 µg/mL concentration showed the highest inhibition of biofilm activity, followed by the highest growth curve, cellular leakage, and potassium ion efflux. The ZnO NPs observed with photo-degradation of Rhodamine-B (Rh-B), Methylene Blue (MB), and Nigrosine dyes under sunlight irradiation at different time intervals. Finally, the photocatalytic activity of LDPE-ZnO NPs nanocomposite film showed the highest degradation under solar light irradiation were confirmed through photo-induced weight loss, SEM, FTIR, and MALDI-TOF analysis. This study demonstrates ZnO NPs exhibit efficacy against biofilm formation, degradation of photocatalytic textile dyes, and low-density LDPE film under solar light irradiation, which can be a step forward in water purification.