Synthesis and characterization of SnS nanosheets through simple chemical route

Tin Sulfide (SnS) nanosheets were synthesized by wet chemical route using ethylene glycol (EG) and without using any surfactant. Structural and phase purity were confirmed by powder X-ray diffraction pattern which shows the orthorhombic structure of SnS. The sheets like morphology and particle size of the synthesized product were identified by using analytical transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM). Agglomeration of SnS nanoparticles was found to lead to the formation of nanosheets. UV-VIS-NIR absorption spectrum of SnS nanosheets shows the direct transition at 1.88 eV. Compared to bulk band gap a blue shift of 0.58 eV has been observed for direct transition. This is due to the quantum confinement effect. Room temperature photoluminescence spectrum of SnS nanosheets shows two emission bands at 1.75 and 1.57 eV respectively which are assigned to band gap and defect level transitions.     

A comparative study of solar irradiation models on various inclined surfaces for India

This paper presents a statistical approach for the estimation of the diffuse/global irradiation on various inclined surfaces from the measured data of horizontal surface. In fact diffuse solar radiation on an inclined plane consists of two components: sky diffuse radiation and reflected radiation from the ground. For analyzing estimation of the daily tilted sky diffuse component from the daily horizontal diffuse irradiance, we have considered six models Badescu, Circumsolar, Skartveit and Olseth, Hay, Klucher and Liu and Jordan (Isotropic). All these models except Badescu adopted the same methodology for estimating the ground-reflected radiation component, therefore, only sky diffuse component was analyzed at Lucknow (latitude 26.75°, longitude 80.50°), India location. Statistical analysis showed that the Skartveit and Olseth model gives good prediction for the low inclination angle however; Klucher model gave better performance for highly inclined south-facing surfaces. The Root Mean Square Errors (% RMSE) value varies from 3.45% to 24.15% except for Badescu and Circumsolar model which predict worse results. In general, Klucher’s model provides close agreement with the measurements.     

Thermodynamic analysis of hydrogen rich synthetic gas generation from fluidized bed gasification of rice husk

In the present work, the generation of hydrogen rich synthetic gas from fluidized bed steam gasification of rice husk has been studied. An equilibrium model based on equilibrium constant and material balance has been developed to predict the gas compositions. The equilibrium gas compositions are compared with the experimental data of the present group as well as of available literature. The energy and exergy analysis of the process have been carried out by varying steam to biomass ratio (ψ) within the range between 0.1-1.5 and gasification temperature from 600 °C to 900 °C. It is observed that both the energy and exergy efficiencies are maximum at the CBP (carbon boundary point) though the hydrogen production increases beyond the CBP. The HHV (higher heating value) and the external energy input both continuously increase with ψ. However, the hydrogen production initially increases with increase in temperature up to 800 °C and then becomes nearly asymptotic. The HHV decreases rapidly with increase in temperature and energy input increases. Therefore, gasification in lower temperature region is observed to be economical in terms of a trade off between external energy input and HHV of the product gas.     

An efficient contrast-enhancement method using the analog to digital converter

The study presents a hybrid method of contrast enhancement using the analog to digital converter (ADC) for use in high-speed industrial applications. The proposed framework processes the digitized image in efficient steps to generate the low and high offsets of the ADC. These offsets are used to modify the analog image signal by an affine transform, such that the digitization of the transformed signalis the enhanced image. Since the signal transformation is mostly done in the analog domain, the method is efficient, and its implementation is inexpensive. As an example, the enhancement method is used in applications where, given images of varying initial contrast, we can obtain an user-specified contrast for all images. These images are then segmented by a simpler image-processing algorithm. The method is a generalization of existing ADC-based enhancement methods and is compared experimentally to the digital domain techniques. An application of the method is given for the enhancement of laser-etched characters on industrial parts.     

Heterogeneous Catalytic Oxidative Bromination and Oxidation of Thioethers By Vanadium(IV) Oxido Complex of Benzoylacetone and Effect of Solid Supports

Vanadium(IV) oxido complex of 1-Phenyl-1,3-butanedione [V^IVO(bzac)₂] (1) was prepared, characterized, and heterogenized onto APTMS modified graphene oxide, as well as imidazole modified polystyrene beads. Graphene oxide supported complex GO-APTMS-[V^IVO(bzac)₂] (2) and polymer anchored complex PS-im-[V^IVO(bzac)₂] (3) were used for the oxidative bromination of a number of small organic molecules and oxidation of a series of thioethers. Both 2 and 3 evolve as excellent heterogeneous catalysts. The nature of solid support does not impact substrate conversion (%) during the oxidative bromination of salicylaldehyde, phenol, or styrene, whereas it influences the substrate conversion (%) as well as the product selectivity (%) during the oxidation of thioethers.

Graphic Abstract

     

A note on diffuse solar radiation on a tilted surface

We are presenting a note on comparative study of diffuse component of solar radiation on tilted surface with different angle of inclination. The monthly mean daily diffuse radiation have been calculated on inclined surfaces from the data of horizontal surface using the Circumsolar and Isotropic model and the anisotropic model of Klucher and Hay at Lucknow (Latitude 26.75°, Longitude 80.85°), Uttar Pradesh, India. These calculated results are compared with our measured value. The comparison shows that Klucher model who considered the effect of cloudy sky conditions gives comparatively good estimations particularly at low inclination angles.     

A simple nonlinear PD controller for integrating processes

Many industrial processes are found to be integrating in nature, for which widely used Ziegler–Nichols tuned PID controllers usually fail to provide satisfactory performance due to excessive overshoot with large settling time. Although, IMC (Internal Model Control) based PID controllers are capable to reduce the overshoot, but little improvement is found in the load disturbance response. Here, we propose an auto-tuning proportional-derivative controller (APD) where a nonlinear gain updating factor α continuously adjusts the proportional and derivative gains to achieve an overall improved performance during set point change as well as load disturbance. The value of α is obtained by a simple relation based on the instantaneous values of normalized error (e_N) and change of error (Δe_N) of the controlled variable. Performance of the proposed nonlinear PD controller (APD) is tested and compared with other PD and PID tuning rules for pure integrating plus delay (IPD) and first-order integrating plus delay (FOIPD) processes. Effectiveness of the proposed scheme is verified on a laboratory scale servo position control system.     

Synthesis and Structural Characterization of V–4Ti–4Cr Alloy

V–(4–10)Ti–(4–5)Cr alloys are the potential candidate materials for the high performance structural applications in fusion power systems due to their favorable mechanical and physical properties. In the present study, the alloy design has been attempted through model based approach for pre mentioned composition range. Thermodynamic calculations have been carried out through Miedema model for this alloy system. The enthalpy difference—composition plot for the ternary V–Ti–Cr system indicate the stability of the solid solution phase in this composition range, which is also in agreement with the atomic size variation which is well within the 15 % size variation limit. Based on these plots, an alloy with a composition of V–4Ti–4Cr is considered as the reference composition for our study. The alloys have been prepared by melting the desired compositions of highly pure metals in a water cooled vacuum arc melting unit. For structural information, X-ray diffraction experiment has been carried out. The XRD pattern does not contain any signature for the secondary phase formation. The structure is bcc structure with small variation in lattice parameter from that of pure vanadium. Transmission electron microscopy characterization has also been carried out, which confirms the absence of fine secondary phases and the crystal structure as b.c.c.