Novel mixed solar cooker: Experimental,energy, exergy,and economic analysis

This work focuses on the structure, working, and testing of a new mixed solar cooker using a linear Fresnel collector, evacuated tube and box-type cooker. The low-cost components used in the construction of this cooker can help it satisfy the needs of both urban and rural inhabitants who need steady cooking temperatures above 140°C. A family of five can prepare four meals using this modified solar cooker, which costs about $250. The designed solar cooker was tested by conducting no-load and full-load tests. For the no-load test, the maximum temperature of the absorber plate and oil for the new mixed cooker was recorded as 160.26°C and 172.72°C, respectively. The absorber plate of the new mixed cooker and its oil both reached their highest temperatures during the full-load test at 141.14°C and 157°C, respectively. The energy efficiency of the new cooker is 58.776%, while its exergy efficiency is 13%. The heat transfer coefficient increased to 100.16 W/m² °C. This cooker provides an additional time savings of 60 min. An improvement of 27.5% in the highest temperature reached was seen when the developed cooker's performance was compared with those reported in the literature. Additionally, the new cooker's heat-storing capability enables up to 3 h of autonomy. The Levelized Cost of Cooking a Meal for the innovative mixed solar cooker is $0.034 per meal.     

Anomalous ferroelectric and magnetic behavior in BPFO-NZFO multiferroic nano-composites

Multiferroic nano-composites (1-x) Bi_.9Pr_.1FeO₃ (BPFO) –x Ni_.5Zn_.5Fe₂O₄ (NZFO) for x?=?0.0, 0.1, 0.2, 0.3 and 1.0 were synthesized by sol-gel auto-combustion method. Detailed investigations were made on the structural, morphological, ferroelectric, magnetic and dielectric properties of these nano-composites. The X-ray Diffraction pattern confirms the co-existence of perovskite BPFO and spinel NZFO phases without any impurity. The average particle size of as prepared BPFO and NZFO nanoparticles is nearly equal to 110?nm and 35?nm respectively which have been confirmed by the XRD and Transmission Electron Microscopy analysis. Structural and surface morphology are studied by Scanning Electron Microscopy. The dielectric properties of the composites are also studied at room temperature. The magnetic hysteresis loop has been studied to know the magnetic response of samples to the applied magnetic field of ±?1?T at room temperature. The saturation and remnant magnetization are found to increase with increase in NZFO weight percentage in the composite. The saturation magnetization values are 8.57?emu/g, 16.71?emu/g, 24.41?emu/g and remnant magnetization values are 0.78?emu/g, 1.23?emu/g, 1.58?emu/g for BPFO-NZFO 1, 2, 3 composite samples respectively. An anomalous ferroelectric behavior of BPFO-NZFO 1 composite sample was observed which can be understand with the help of observed results in dielectric and morphology of the samples. The incorporation of BPFO and NZFO enhances the multiferroic properties in the present composite materials which are quite promising from application point of view.     

Eye gaze tracking based directional control interface for interactive applications

This paper proposes an unobtrusive and calibration-free framework towards eye gaze tracking based interactive directional control interface for desktop environment using simple webcam under unconstrained settings. The proposed eye gaze tracking involved hybrid approach designed by combining two different techniques based upon both supervised and unsupervised methods wherein the unsupervised image gradients method computes the iris centers over the eye regions extracted by the supervised regression based algorithm. Experiments performed by the proposed hybrid approach to detect eye regions along with iris centers over challenging face image datasets exhibited exciting results. Similar approach for eye gaze tracking worked well in real-time by using a simple web camera. Further, PC based interactive directional control interface based upon iris position has been designed that works without needing any prior calibrations unlike other Infrared illumination based eye trackers.

The proposed work may be useful to the people with full body motor disabilities, who need interactive and unobtrusive eye gaze control based applications to live independently.

     

Support modification to improve the sulphur tolerance of Ag/Al2O3 for SCR of NOx with propene under lean-burn conditions

Ag/Al₂O₃ catalysts with 1 wt% SiO₂ or TiO₂ doping in alumina support have been prepared by wet impregnation method and tested for sulphur tolerance during the selective catalytic reduction (SCR) of NO_x using propene under lean conditions. Ag/Al₂O₃ showed 44% NO_x conversion at 623 K, which was drastically reduced to 21% when exposed to 20 ppm SO₂. When Al₂O₃ support in Ag/Al₂O₃ was doped with 1 wt% SiO₂ or TiO₂ the NO_x conversion remained constant in presence of SO₂ showing the improved sulphur tolerance of these catalysts. Subsequent water addition does not induce significant deactivation. On the contrary, a slight promotional effect on the activity of NO conversion to nitrogen is observed after Si and Ti incorporation. FTIR study showed the sulphation of silver and aluminum sites of Ag/Al₂O₃ catalysts resulting in the decrease in the formation of reactive intermediate species such as –NCO, which in turn decreases NO_x conversion to N₂. In the case of Ag/Al₂O₃ doped with SiO₂ or TiO₂, formation of silver sulphate and aluminum sulphate was drastically reduced, which was evident in FTIR resulting in remarkable improvement in the sulphur tolerance of Ag/Al₂O₃ catalyst. These catalysts before and after the reaction have been characterized with various techniques (XRD, BET surface area, transmittance FTIR and pyridine adsorption) for physico-chemical properties.     

Equilibrium adsorption studies on removal of diclofenac sodium from aqueous solution using sawdust–polyaniline (SD–PAn) composites

In this work, equilibrium adsorption studies were carried out for the removal of antiinflamatory drug diclofenac sodium (DS) from aqueous solutions using sawdust–polyaniline(SD-PAn) composite as a potential sorbent at 20, 30, and 40°C. The composite sorbent was characterized by FTIR and SEM analysis. The particles exhibited porous and rough surface. The equilibrium uptake data was interpreted by the Langmuir, the Freundlic, the Temkin, and the Dubinin–Redushkevich (D -R) isotherm models. The maximum adsorption capacity was found to decrease with increase in temperature, thus indicating exothermic nature of the adsorption process. The thermodynamic parameters were evaluated using Langmuir, Flory–Huggins, Frumkin, and modified-Frumkin models. The negative values of ΔG_ads⁰ and ΔH⁰ indicated spontaneous and exothermic nature of the adsorption process, respectively. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci 125:1382–1390, 2012     

Development of bimetal-grown multi-scale carbon micro-nanofibers as an immobilizing matrix for enzymes in biosensor applications

This study describes the development of a novel bimetal (Fe and Cu)-grown hierarchical web of carbon micro-nanofiber-based electrode for biosensor applications, in particular to detect glucose in liquids. Carbon nanofibers (CNFs) are grown on activated carbon microfibers (ACFs) by chemical vapor deposition (CVD) using Cu and Fe as the metal catalysts. The transition metal-fiber composite is used as the working electrode of a biosensor applied to detect glucose in liquids. In such a bi-nanometal-grown multi-scale web of ACF/CNF, Cu nanoparticles adhere to the ACF-surface, whereas Fe nanoparticles used to catalyze the growth of nanofibers attach to the CNF tips. By ultrasonication, Fe nanoparticles are dislodged from the tips of the CNFs. Glucose oxidase (GOx) is subsequently immobilized on the tips by adsorption. The dispersion of Cu nanoparticles at the substrate surface results in increased conductivity, facilitating electron transfer from the glucose solution to the ACF surface during the enzymatic reaction with glucose. The prepared Cu-ACF/CNF/GOx electrode is characterized for various surface and physicochemical properties by different analytical techniques, including scanning electron microscopy (SEM), electron dispersive X-ray analysis (EDX), Fourier-transform infrared spectroscopy (FTIR), BET surface area analysis, and transmission electron microscopy (TEM). The electrochemical tests show that the prepared electrode has fast response current, electrochemical stability, and high electron transfer rate, corroborated by CV and calibration curves. The prepared transition metal-based carbon electrode in this study is cost-effective, simple to develop, and has a stable immobilization matrix for enzymes.     

Differentiation of big-six non-O157 Shiga-toxin producing Escherichia coli (STEC) on spread plates of mixed cultures using hyperspectral imaging

There have been considerable recent advances in the technology for rapidly detecting foodborne pathogens. However, a traditional culture method is still the “gold standard” for presumptive-positive pathogen screening although it is labor-intensive, ineffective in testing large amount of food samples, and cannot completely prevent unwanted background microflora from growing together with target microorganisms on agar media. We have developed multivariate classification models based on visible and near-infrared hyperspectral imaging for rapid presumptive-positive screening of six representative non-O157 Shiga-toxin producing Escherichia coli (STEC) serogroups (O26, O45, O103, O111, O121, and O145) on agar plates of pure and mixed cultures. The classification models were developed with spread plates of pure cultures. In this study, we evaluated the performance of the classification models with independent validation samples of mixed cultures that were not used during training and found the best classification model for differentiating non-O157 STEC colonies on spread plates of mixed cultures. A validation protocol appropriate to hyperspectral imaging of mixed cultures was developed. An additional independent validation set of 12 spread plates with pure cultures was used as positive controls to help the validation process with the mixed cultures and to affirm the model performance. One imaging experiment with colonies obtained from two serial dilutions was performed. A total of six agar plates of mixed cultures were prepared, where O45, O111 and O121 serogroups that were relatively easy to differentiate were inoculated into all six plates and then each of O26, O103 and O145 serogroups was added into the mixture of the three common bacterial cultures. The number of mixed colonies grown after 24-h incubation was 331 and the number of pixels associated with the grown colonies was 16,379. The best model found from this validation study was based on pre-processing with standard normal variate and detrending, first derivative, spectral smoothing, and k-nearest neighbor classification (kNN, k = 3) of scores in the principal component subspace spanned by 12 principal components. The results showed 95 % overall detection accuracy at pixel level and 97 % at colony level. The developed model was proven to be still valid even for the independent validation samples although the size of a validation set was small and only one experiment was performed. This study was an important first step in validating and updating multivariate classification models for rapid screening of ground beef samples contaminated by non-O157 STEC pathogens using hyperspectral imaging.     

Performance analysis of dynamic voltage restorer using improved PSO technique

ABSTRACT

This paper has discussed the study of the performance of dynamic voltage restorer (DVR) taking different voltage sag conditions in the supply voltage of the distribution system for linear and non-linear load. DVR is employed to mitigate the voltage sag. Proportional and integral (PI) controller is used for the control of DVR to mitigate the voltage sag. Synchronous reference frame theorybased control algorithm has been implemented for generating reference voltages. In this paper, an efficient improved particle swarm optimisation technique for optimizing the gain parameters of the PI controller has been proposed. The performance and suitability of DVR is validated through MATLAB simulation results and use of Sim Power Systems Blocksets. Integral squared error is implemented to check the performance and suitability of DVR. Extensive results of the proposed method are presented and compared with conventional Ziegler Nichols and genetic algorithm methods of tuning gain parameters of PI controllers.