Analysis and Experiment of Self-Powered,Pulse-Based Energy Harvester Using 400 V FEP-Based Segmented Triboelectric Nanogenerators and 98.2% Tracking Efficient Power Management IC for Multi-Functional IoT Applications

A self-powered system for the Internet of Things (IoT) is demonstrated for efficient energy harvesting of naturally available mechanical energy. In this system, new contact-separation mode triboelectric nanogenerators (TENGs), based on fluorinated ethylene propylene, are investigated using the segmented multi-TENG configuration to reduce the effect of parasitic capacitance. The TENG extraction is optimized using a unit step excitation involved with the Dawson function to achieve a high voltage (400 V) and a high current (26.6 µA). To fully extract the power of the TENGs, the power management integrated circuit (PMIC) specially designed for adaptively controlled, high-voltage (HV) maximum power point tracking (MPPT) is proposed. The PMIC implemented in a bipolar CMOS-DMOS 180 nm process can handle a wide input range (5–70 V) by consuming 420 nW. The MPPT control allows a wide range of impedance matching from 10 to 300 MΩ, achieving a tracking efficiency of up to 98.2%. The end-to-end efficiency of 88% demonstrates state-of-the-art performance. To supply a higher instantaneous power than that available from the TENGs, a duty-cycling technique is successfully demonstrated. The proposed energy harvesting system provides a promising approach to realizing sustainable and autonomous energy sources for various IoT applications.     

Elastic-plastic J and COD estimation schemes for throughwall circumferentially cracked elbow under in-plane closing moment

Leak-before-break (LBB) assessment of primary heat transport piping of nuclear reactors involves detailed fracture assessment of pipes and elbows with postulated throughwall cracks. Fracture assessment requires the calculation of elastic-plastic J-integral and crack opening displacement (COD)¹ for these piping components. Analytical estimation schemes to evaluate elastic-plastic J-integral and COD simplify the calculations. These types of estimation schemes are available for pipes with various crack configurations subjected to different types of loading. However, no such schemes are available for throughwall circumferentially cracked elbow (or pipe bend), an important component for LBB analysis. In this paper, simple J and COD estimation schemes are proposed for throughwall circumferentially cracked elbow subjected to closing bending moment. The ovalisation of elbow cross-section has a significant bearing on its fracture behavior. Therefore, unlike conventional deformation theory plasticity analysis, incremental flow theory is adopted considering both material and geometric non-linearities in the development of the proposed estimation schemes. Although it violates Ilyushin’s theorem, it has been shown that the resulting estimation schemes is still reasonably accurate for engineering purposes. Finally, experimental/numerical validation has been provided by comparing the J-integral and COD between numerical/test data and predictions of the proposed estimation schemes.     

An investigation of neuro-fuzzy systems in psychosomatic disorders

A neuro-fuzzy model for diagnosis of psychosomatic disorders is proposed in this paper. The symptoms and signs are collected from the patients through oral interview. For the linguistic nature of patient's inputs, an artificial domain is created and fuzzy membership values are defined. The fuzzy values are fed as inputs to feedforward multilayer neural network. The network is trained using Backpropagation training algorithm. The trained model is tested with new patient's symptoms and signs. Further, the performance of the diagnosing capability is compared with medical expert. The performance of the model is also compared with probability model based on Bayesian Belief Network and statistical model using Linear Discriminant analysis     

Bending strength of composite laminates with an elliptical hole

Great efforts have been made in analyzing the strength of notched laminates under in-plane loadings. However, no work has been reported on notched laminates under bending, because of the complexity of theoretical stress analysis. In this study, a simplified approach has been used to analyze the notched strength of laminated composites with an elliptical hole under bending. This approach combines notched sample experiments and finite element results. Based upon the consideration that not only the stress distribution at one ply, but also the stress variation across the laminate thickness, should be taken into account, two failure models are presented: a modified point stress model and a modified average stress model. Two characteristic parameters are presented to evaluate the notched strength of the laminated plates.     

Effect of various concentrations of lead nitrate on the induction of micronuclei in mouse bone marrow

The frequency of micronuclei was evaluated in the bone marrow of mice of either sex administered with 0, 0.625, 1.25, 2.5, 5, 10, 20, 40 and 80 mg/kg b.wt of lead nitrate at 12, 24 and 36 h post-treatment. The frequency of micronucleated polychromatic erythrocytes (MPCE) and micronucleated normochromatic erythrocytes (MNCE) increased significantly at 12, 24 and 36 h after treatment with lead nitrate compared to non-drug treated controls. The frequency of micronuclei did not show a dose related increase and the elevation in the frequency of micronuclei was fluctuating type. One important observation which emerged from this study was that the male mice were more sensitive to the induction of micronuclei compared to female mice. This was evidenced by higher frequencies of MPCE in males than females at all the doses for all the post-treatment time periods. The lead nitrate treatment resulted in a spurt in the erythropoiesis as is evidenced by a significant increase in the ratios of polychromatic to normochromatic erythrocytes (P/N ratio) compared to non-drug treated controls at 12, 24 and 36 h post-treatment. The P/N ratio was significantly higher in females than males at 12 and 24 h post-treatment.     

Shape, wear & mechanical properties of spray formed hypoeutectic Al-Si alloys

Manufacturing process through spray forming leads to give near-net-shape and fine grain microstructure. In this process Si particles, which are not distributed uniformly in conventional casting process, are distributed uniformly throughout the casting. In the present study disc shape spray form castings were made of Al-6.91Si and Al-10.1Si alloys, and then their shape, wear and mechanical properties were studied. The shape of the deposit was observed to be the most uniform at 30o inclination angle of the substrate. The hardness and tensile strength value of spray formed alloys shows the increment in the mechanical property in contrast to as cast alloys. The wearing properties of Al-10.1Si alloy were found to be better than that of the Al-6.91Si alloy.     

Ionomeric poly(urethane semicarbazides) with azobenzene groups in the main chain – studies on photoswitching behaviour and mechanical properties

Poly(urethane semicarbazide) anionomers containing azobenzene chromophores in the main chain were prepared by chain extending the isocyanate terminated prepolymers with chromophoric dihydrazide. Variations were done with respect to the hard segment content and the nature of the diisocyanate and the effect of the variations on the thermal, mechanical properties and wettability were studied. The polymers in solution showed reversible photoisomerization behaviour evinced by UV/vis spectroscopy in which irradiation of polymer solutions with UV light was observed as a decrease in intensity of absorbance corresponding to trans-form and increase in the absorbance of cis-form. The back relaxation took place in the presence of visible light. Photoswitching or the wettability of the films induced by the reversible cis–trans isomerization of the azobenzene chromophores was experimentally shown from water contact angle measurements. Irradiation of the films with 365 nm light effected a decrease in the water contact angle. X-ray diffraction results indicated dense arrangement of crystallized hard segments in compositions containing higher hard segment content. Thermal stability up to 300 °C was exhibited by the polymers as shown by thermogravimetric analysis and the phase separated morphology was confirmed by dynamic mechanical analysis. Tensile strength measurements showed that the films with increasing hard segment content exhibited increasing tensile strength and modulus but decreasing values of elongation.     

Catalyst‐Free Synthesis and Characterization of Metastable Boron Carbide Nanowires

Catalyst‐free growth of boron carbide nanowires is achieved by pyrolysis of diborane and methane at 650–750 °C and around 500 mTorr in a quartz tube furnace. Electron‐diffraction analysis using a novel diffraction‐scanning transmission electron microscopy (D‐STEM) technique indicates that the crystalline nanowires are single‐crystal orthorhombic boron carbide. TEM images show that the nanowires are covered by a 1–3 nm thick amorphous layer of carbon. Elemental analysis by electron energy loss spectroscopy (EELS) shows only boron and carbon while energy‐dispersive X‐ray spectroscopy (EDX) and X‐ray photoelectron spectroscopy (XPS) show the presence of oxygen as well as boron and carbon.     

Evaluation of flyash-filled and aramid fibre reinforced hybrid polymer matrix composites (PMC) for friction braking applications

Flyash-filled and aramid fibre reinforced phenolic based hybrid polymer matrix composites (PMC) were fabricated followed by their characterization and tribo-evaluation. The friction-fade and friction-recovery behaviour has been rigorously evaluated as a function of in situ braking induced temperature rise in the disc at the braking interface on a Krauss friction testing machine as per the ECE regulations. The fade behaviour has been observed to be highly dependent on the weight fraction of resin i.e. followed a consistent decrease with the decrease in the flyash content, whereas the frictional fluctuations (μ_max − μ_min) has been observed to decrease with the increase in flyash content. A higher recovery response is registered when the flyash content is 80 wt.%. The analysis of friction performance has revealed that the fade and static friction response are the major determinants of overall frictional response. Wear analysis has revealed that material integrity and temperature rise of the disc decide the wear behaviour. Worn surface morphology investigation using SEM has revealed that the dynamics of formation–destruction of contact-patches (friction-layers) and topographical attributes largely influence the friction and wear performance of such composite brake-pads.     

Modified solution combustion route for the preparation of plasma sprayable ceria powder

Plasma sprayable grade ceria powder was prepared by the solution combustion method. This is the first report on the application of solution combustion for the synthesis of plasma sprayable grade oxide powders. The fuels and fuel ratios used in the solution combustion were modified to achieve adequate flowability. It was found that when a mixture of fuels like glycine and ammonium acetate was used, the combustion process yielded larger agglomerates. Phase purity of the powders was confirmed by powder XRD. The morphology of the particles was determined by scanning electron microscopy.