In-plane compression porometry of battery separators

We have designed equipment that measures, by means of capillary flow porometry, the pore structure of sheet materials. The equipment measures the influence of superimposed compressive stress on pore structure as well. The bubble point pressure, mean flow pressure, and flow distribution of a battery separator have been measured, and the influence of compressive stresses on these parameters have been observed. Our results demonstrate that the pore structure for in-plane flow is considerably different from that for flow in the perpendicular direction, and the effect of superimposed compressive stress is appreciable.     

Impact strength and dynamic mechanical properties correlation in elastomer‐modified polypropylene

This article describes the impact and dynamic mechanical properties of rubber‐modified binary blends of polypropylene (PP). Two conventional elastomers [viz. ethylene vinyl acetate copolymer (EVA) and ethylene propylene diene terpolymer (EPDM)] were used as an impact modifier for PP. It is clearly indicated by the results that EPDM is better than EVA as an impact modifier of PP. Analysis of data of dynamic mechanical properties and impact properties at various compositions of the blends revealed a direct correlation between impact properties and dynamic mechanical loss tangent. The energy dissipation due to viscoelastic relaxation is therefore suggested as a mechanism of impact toughening of PP, in addition to the other commonly known mechanisms of toughening (viz. shear yielding and crazing induced by deformation of rubber‐phase domains). © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 962–971, 2000     

Energy harvesting-enabled energy-efficient routing using spotted hyena optimization in wireless sensor network

With the continuous proliferation of sensing technology, it has become possible to utilize energy harvesting (EH)-enabled sensor nodes for a variety of applications. However, conventional wireless sensor networks (WSNs), that is, those without EH-enabled nodes, still have limited applicability due to their limited battery resources. Further, the utilization of EH-enabled nodes in the network not only imposes a financial burden on the user but also limits its performance due to its dependence on environmental conditions. To address this concern, in this paper, we propose the EH-enabled energy-efficient routing (EHEER) technique for green communication in WSN. The predominant concern being addressed in this paper is the selection of cluster head (CH), which helps in gathering, aggregating and forwarding the data from the cluster-based routing paradigm. We use the spotted hyena optimizer (SHO) algorithm for optimizing the fitness parameters for CH selection, namely, energy ratio, distance considerations, node density, load balancing and the network's average energy. We use EH-enabled nodes in the network strategically so as to keep control over the costs incurred in the network. The simulation outcomes empirically prove the efficacy of the proposed work, as it effectively increases the network stability and operational period by a huge margin as compared to the existing techniques.     

Synthesis and characterization of polysiloxanes for controlled release of 2-pyridine aldoxime–chloride

A number of polysiloxanes and their copolymers were synthesized by hydrolytic polycondensation of dialkyl (ary) dichlorosilane or their mixtures in a saturated solution of NaCl in water at low temperature (0–5°C). These polysiloxanes were characterized by intrinsic viscosity, infrared and nuclear magnetic resonance spectroscopy. 2-Pyridine aldoxime–chloride (PAM–Cl) was incorporated into these polysiloxanes, followed by crosslinking with tetraethoxysilane using dibutyltindilaurate as catalyst. The effect of pH on in vitro release rate of PAM–Cl from polysiloxane matrices was investigated in phosphate buffer of pH 3.0, 7.4, and 10.0 at 37°C using an ultraviolet spectrophotometer. Transport parameters like the order of release and diffusion coefficients for these systems (polysiloxane—PAM–Cl) were also calculated. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1837–1846, 1998     

Reaction rate enhancement during swollen-state polymerization of poly(ethylene terephthalate)

Experimental data are obtained for the extent of swelling and progress of the step-growth swollen-state polymerization (SwSP) of polyethylene terephthalate (PET). The SwSP is carried out in biphenyl and diphenyl ether mixture (26 : 74 w/w) solvent under appropriate conditions designed to understand the factors responsible for enhanced reaction rates. The kinetics rate constants, evaluated in terms of simple model, are found to be 2.5–5 times higher for SwSP as compared to the solid-state polymerization (SSP). As the diffusional/mass transfer effects are eliminated in our experiments, this increase in rate constants can be attributed to increased mobility of reactive chain ends. Polymerization rate is found to be further enhanced by addition of a polycondensation catalyst (Sb₂O₃) to the solvent during SwSP. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1589–1595, 1998     

Recent trends in design and analysis of Rotman-type lens for multiple beamforming

Modified geometries for a Rotman-type bootlace lens have been proposed. The effects of design parameters on the shape of the lens and on the path length error have been investigated. The proposed geometries have been analyzed by the contour integral approach. Results obtained for the proposed lenses have been compared. © 1998 John Wiley & Sons, Inc. Int J RF and Microwave CAE 8: 321–338, 1998.     

Poly (2-hydroxyethyl methacrylate)-based hydrogels for slow release of pralidoxime chloride

Pralidoxime chloride (PAM-Cl)-loaded poly (2-hydroxyethyl methacrylate) (PHEMA)-based hydrogels were prepared by bulk copolymerization of 2-hydroxyethyl methacrylate (HEMA) with different mol fractions (0.02–0.10) of trimethylsilyl methacrylate. Characterization of the gels was done by dynamic swelling measurements. It was found that copolymerization does not alter the swelling mechanism of PHEMA and it essentially remains Fickian in nature. In vitro drug-release studies show the increase in release time from 6 to 12 h on incorporation of a 0.1 mol fraction of trimethylsilyl methacrylate on the PHEMA backbone. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 267–270, 1997     

Octree-based hierarchical distance maps for collision detection

Discretized distance maps have been used in robotics for path planning and efficient collision detection applications in static environments.¹ However, they have been used at the finest level of resolution, thereby making them memory intensive. In this article, we propose an octree-based hierarchical representation for discretized distance maps, called Octree Distance Maps (ODM), and show its use in efficient collision detection. To the best of our knowledge, ours is the first work to consider the use of hierarchical distance maps for collision detection. ODM representation achieves an advantageous compromise between array-based distance maps and ordinary octrees. Compared to the former, ODM requires a fraction of the memory at the expense of somewhat slower collision detection. Compared to the latter, ODM requires slightly more memory but provides a significant improvement in collision detection. ODM is similar to the quadtree distance transforms used in image representation² but differs significantly in various aspects of distance representation and its use in collision detection since the main motivation behind ODM is efficient collision detection instead of image representation. We then present algorithms for (1) creating an ODM from an octree, and (2) for efficient collision detection based on an ODM. Extensive experiments are then presented and compared with octree-based collision detection. Our experimental results quantify the advantageous compromise achieved by ODM representation. © 1997 John Wiley & Sons, Inc.