A multisource energy harvesting utilizing highly efficient ferroelectric PMN-PT single crystal

This paper demonstrates a multi-source energy harvester that is able to utilize simultaneously both piezoelectric and pyroelectric effects in lead magnesium niobate-lead titanate (PMN-PT) single crystal. The paper presents a study of PMN-PT single crystal with a (67:33) composition grown in our laboratory via a vertical gradient freeze method without any flux. The performance of the piezoelectric and pyroelectric energy harvester using unimorph device structure was evaluated via modeling and experiment. The theoretical study was implemented based on a distributed parameter electromechanical model and the modelling procedure was approximated using finite element analysis to predict the electromechanical behavior of the harvester. The maximum power density at a resonance frequency of 50 Hz and optimum resistance of 2 MΩ was 16.7 nW/(g² cm³) under a 1 g acceleration of vibration. The measured values of electrical output parameters were in good agreement with theoretical and modelling results using MATLAB and COMSOL Multiphysics, respectively. By using the pyroelectric effect along with the piezoelectric effect, the output voltage of the energy harvester was found to be enhanced at the optimum resistance and specific frequency values. It was noticed that the output voltage was increased monotonically with temperature-difference (ΔT) and reaches up to 180 % of its original value under temperature difference of 1.7 °C at a frequency value of 49 Hz.     

Image coding based on maximum entropy partitioning for identifying improbable intensities related to facial expressions

In this paper we investigate information-theoretic image coding techniques that assign longer codes to improbable, imprecise and non-distinct intensities in the image. The variable length coding techniques when applied to cropped facial images of subjects with different facial expressions, highlight the set of low probability intensities that characterize the facial expression such as the creases in the forehead, the widening of the eyes and the opening and closing of the mouth. A new coding scheme based on maximum entropy partitioning is proposed in our work, particularly to identify the improbable intensities related to different emotions. The improbable intensities when used as a mask decode the facial expression correctly, providing an effective platform for future emotion categorization experiments.     

Impedance studies of polycrystalline tin oxide

Polycrystalline SnO₂ samples prepared in the laboratory were irradiated with 2 MeV He ions having doses of 3.62 × 10¹⁵ ion/cm². The ac small-signal electrical data acquired for the polycrystalline SnO₂ in the frequency (f) range 100 Hz ≤ f ≤ 1 MHz and temperature (T) range 26°C ≤ T ≤ 100°C revealed one semicircular relaxation in the impedance plane for the He implanted sample. However, two semicircular relaxations were obtained in the same plane for the samples without He implantation. The He implantation indicated enhancement in the donor density in the polycrystalline SnO₂ as depicted via terminal conductance (or resistance). An erratum to this article can be found at     

Thermo-optic coefficient of barium gallogermanate glass

Barium gallogermanate (BGG) glasses are currently being explored as a viable low cost material for numerous U.S. defense and commercial visible-infrared window applications. These glasses are transparent from 0.4 mum to beyond 5.0 mum and can be easily made in large optics and complex shapes with high index homogeneity. For high-energy laser (HEL) applications, knowledge of the thermo-optic coefficient (dn/dT) of the window material is important in determining the optical path distortion. The dn/dT measurements were made on BGG glass at 633 and 3390 nm and compared with the values for multispectral ZnS. The dn/dT for BGG glass was approximately 1/5 the value for multispectral ZnS, giving BGG glass a clear advantage for HEL applications.     

The component acids of kamala oil (Mallotus Philippinensis,Muell. Arg.)

Summary Kamala oil has been found to contain about 60% of kamlolenic acid as the only major component with minor proportions of common linoleic, oleic, and saturated acids and probably some conjugated diethenoid acid. The saturated components consist mostly of myristic and palmitic acids. Consecutive extraction of kamala seeds with petroleum ether and ethyl ether yields two fractions of the oil, containing about 40% and 80% of kamlolenic acid, respectively. During storage a portion of the unsaturated glycerides seems to undergo polymerization within the seed itself and appears as an insoluble gelatinous mass during saponification of the oil.     

Reliability estimation for probabilistic switching circuits

A simple technique for the reliability estimation of switching circuits is developed. A Table is prepared for reliability expressions of basic logic modules. These expressions are then used for the reliability evaluation of complex switching circuits.     

Structure and properties of microcomposites and macrocomposites from block polymers

The incorporation of a rubber phase in glassy polymers, as is well known in the case of high impact polystyrene, leads-to an increase in their impact strength. Block polymers offer three principal approaches for obtaining multiphase glassy polymers in which an elastorner phase is present in the matrix of the glassy polymer. They are: (1) control ofblock polymer composition, (2) blending of block polymer with homopolymers, and (3) polymerization of a solution.of a block polymer in the monomer corresponding to one of the blocks. The observed properties, such as impact strength, modulus, and heat distortion temperature, desired in rubber modified glassy polymers are discussed for block polymer systems prepared using the above approaches.