Effect of Cu concentration on the photoconductivity properties of ZnS nanoparticles synthesized by co-precipitation method

In the present work, solution based co-precipitation method has been used to prepare Cu-doped ZnS nanoparticles and characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), UV–vis absorption spectroscopy and photoconductivity (PC). XRD analysis shows the cubical zinc blende structure while for higher doping concentration extra peaks of CuS have been observed. The estimated crystallite sizes of Cu-doped ZnS lies in the range of 2–4 nm. SEM micrographs show spherical shape of nanoparticles. UV–vis absorption study shows blue shift of absorption shoulder for un-doped and Cu-doped ZnS NPs as compared to the bulk counterpart. In photoconductivity study, the enhancement of photosensitivity has been observed in 4% Cu-doped sample while the maximum current is found in 1% Cu-doped sample. The substitution of Cu is found to affect the photoconductivity properties owing to the CuS phase. The variation of darkcurrent and photocurrent with applied voltages exhibits super-linear nature (r>1). Negative photoconductivity (NPC) is observed in all the samples in which the photocurrent decreases during steady illumination.     

FGMOS based tunable grounded resistor

This paper proposes a novel floating gate MOSFET (FGMOS) based tunable grounded resistor (FGTGR). The FGTGR has been implemented using a single 3-input FGMOS. In the drain current equation of 3-input FGMOS, the gate voltage is equal to the weighted-sum of the 3 input voltages, namely V _in (input voltage), V _C (control voltage), and V _b (bias voltage). The input gate voltage (V _in ) with appropriate conditions has been used to cancel the nonlinear-term present in the drain current equation of FGMOS operating in the ohmic region. The control voltage V _C has been used to control the resistor value and the bias voltage V _b has been used to realize either a threshold-dependent or a threshold-independent FGTGR. The FGTGR is simple, compact, accurate, and with low power dissipation of 1.63 μW. The workability of the FGTGR and the high pass filter realized by using the same, have been confirmed by SPICE simulations in 0.5 μm CMOS technology.     

Experimental study of the effect of digitizing parameters on digitizing uncertainty with a CMM

Planning of an automated digitization or inspection process takes time and requires experience. The accuracy of digitization and inspection depends directly on the planning of digitization strategies. This paper uses the fractional factorial experimentation approach to investigate the relationship between digitizing (inspection) uncertainty and digitizing (inspection) parameters with a coordinate-measuring machine (CMM). The parameters include travel speeds, pitch, probe angles (part orientations), probe sizes and feature sizes. Robust digitization (inspection) strategies are identified given the part geometry, dimensions and accuracy. Finally, future research directions are highlighted.     

Agent-based design framework for riser and gating system design for sound casting

A multi-agent control framework is proposed that is capable of designing a rising and gating system for a three-dimensional computer-aided design model of a casting. The proposed framework uses autonomous and self-communicating agents to interact with the environment and to extract knowledge from it. Agents are capable of taking the optimal decision related to the various facets of casting design. Information on the computer-aided design model of casting is fed into the system through which a casting agent is generated. Other agents like a riser agent, an ingate agent, a runner agent and a sprue agent are the offshoots emanated from the casting agent. They interact with each other to share detailed information related to the riser and gating system design. The proposed multi-agent framework focuses on autonomous real-time analysis required to generate geometric shapes without much involvement of the user.     

Sn-Doped In2O3 Nanocrystalline Thin Films Deposited by Spray Pyrolysis: Microstructural, Optical, Electrical, and Formaldehyde-Sensing Characteristics

Undoped and Sn-doped (1, 1.5 and 2 at.%) indium oxide (In₂O₃) thin films have been grown by the chemical spray pyrolysis technique on cleaned glass substrates using indium nitrate [In(NO₃)₃] and stannic tetrachloride hydrated (SnCl₄·5H₂O) as the host and dopant precursors, respectively, and deionized water as the solvent. Structural characterization using x-ray diffraction reveals that the films possess cubic structure, with the average crystallite size in the range 10-14 nm. The surface morphology and roughness of the films have been investigated by means of an atomic force microscope. UV-Vis measurements indicate an enhancement in the optical transmittance in the visible region on Sn doping. Further, the doping effect has been found to substantially reduce the electrical resistance to a few orders of magnitude of the undoped In₂O₃ film. We report a simultaneous improvement in both the optical and electrical properties of indium oxide thin film due to the doping of Sn ions. These results indicate that Sn-doped In₂O₃ thin film can be a potential candidate for use in various optoelectronic devices. Among all the films examined, the 1 at.% Sn-doped film shows the maximum response (~91%) at 300 °C for 80 ppm concentration of formaldehyde in air.     

Negative ion beam extraction in ROBIN

The RF based single driver ?ve ion source experiment test bed ROBIN (Replica Of BATMAN like source in INDIA) has been set up at Institute for Plasma Research (IPR), India in a technical collaboration with IPP, Garching, Germany. A hydrogen plasma of density 5 × 10¹² cm^?3 is expected in driver region of ROBIN by launching 100 kW RF power into the driver by 1 MHz RF generator. The cesiated source is expected to deliver a hydrogen negative ion beam of 10 A at 35 kV with a current density of 35 mA/cm² as observed in BATMAN.In first phase operation of the ROBIN ion source, a hydrogen plasma has been successfully generated (without extraction system) by coupling 80 kW RF input power through a matching network with high power factor (cos θ > 0.8) and different plasma parameters have been measured using Langmuir probes and emission spectroscopy. The plasma density of 2.5 × 10¹¹ cm^?3 has been measured in the extraction region of ROBIN. For negative hydrogen ion beam extraction in second phase operation, extraction system has been assembled and installed with ion source on the vacuum vessel. The source shall be first operated in volume mode for negative ion beam extraction. The commissioning of the source with high voltage power supply has been initiated.     

SYNTHESIS OF COPPER METAL/SALTS FROM COPPER BLEED SOLUTION OF A COPPER PLANT

Copper bleed solution (CBS) generated during the electrorefining of anode copper contains 40 g/L Cu, 10–20 g/L Ni, and 170–200 g/L H₂SO₄, along with other impurities in different quantities. In order to get the valuable metals from this CBS, studies have been carried out to crystallize and recover metal salts on bench scale with/without partial decopperization from the point of view of reuse and the recycling of the sulphate salts and the acid recovered back to the system. Studies showed the possibility of recovering copper sulphate salt without affecting its purity with respect to nickel by controlling the extent of evaporation. In an alternative approach, a part of copper metal of purity 99.85% produced during partial decopperization of copper from 39.8 to 9.64 g/L Cu without affecting the current efficiency at a current density of 100 A/m². Subsequently, mixed salt containing 9.80% Cu and 13.19% Ni has also been produced from the partially decopperized solution. The mixed salt could be processed for metal recovery by solvent extraction. The mother and wash liquor could be recycled in the electrorefining plant for acid and copper make-up.     

Frequency Regulation in Hybrid Power System Using Iterative Proportional-Integral-Derivative H ∞ Controller

This study considers frequency regulation in a hybrid power system consisting of conventional and distributed generation resources. The performance of two controllers—an H _∞ design via linear matrix inequalities and an iterative proportional-integral-derivative H _∞ via linear matrix inequalities—is assessed to maintain frequency deviation profile in acceptable limits. In the latter control design, the iterative linear matrix inequality approach is used to tune proportional-integral-derivative controller parameters subjected to H_∞ constraints in terms of the iterative linear matrix inequality. The efficacy of the control law and disturbance accommodation properties is shown. The robustness of these controllers is demonstrated in the hybrid power system with different load disturbance conditions, wind power, and parameter variations. Controller performance is compared with a suboptimal controller to demonstrate its superiority. It is found that the second controller design has satisfactory disturbance rejection properties and robustness against parameter variations over a wide range of conditions.     

Interaction Study of Yttria‐Based Glasses with High‐Temperature Electrolyte for SOFC

The chemical interaction study of AO–SiO₂–B₂O₃–Y₂O₃ (A = Ba, Sr) (BaY, SrY) glass with high‐temperature electrolyte yttria‐stabilized zirconia (YSZ 8 mol%) is reported as a function of different heat treatment durations. The as‐prepared glass with 10 mol% of yttria shows limited amount of crystallization at 800 °C. Due to this yttria‐based glasses BaY and SrY have been chosen to make diffusion couples with high‐temperature electrolyte and interconnect material. These diffusion couples have been heat treated at 850 °C, for 100, 200, and 500 h. The heat‐treated diffusion couples have been characterized using X‐ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). Microstructural analysis of diffusion couples shows absence of any undesired oxides and detrimental reaction products at the interface. The glass has shown good bonding characteristics and absence of cracks, pores, or any kind of delamination from YSZ. Apart from this, SrY and BaY glass seals have also shown good adhesion characteristics with Crofer 22 APU, even after 500 h at 850 °C. The morphology and microstructure of the glass matrix suggest limited amount of devitrification in the glass.     

Experimental investigation on deformation and wear of WC tool during friction stir welding (FSW) of stainless steel

In this paper, the effect of friction stir welding (FSW) parameters on wear and deformation behavior of tungsten carbide (WC) tool employed in the welding of AISI 304 austenitic stainless steel (SS) is reported. In addition, the wear and deformation of the tool are also characterized. Three FSW parameters, namely shoulder diameter, tool rpm, and traverse speed each at three levels were considered. Experiments were performed as per Taguchi’s L₉ orthogonal array to investigate the effect of these parameters on wear and plastic deformation of the tool. Wear at the pin root and bottom face of the pin attributed to diffusion and attrition mechanisms, respectively, were observed. Significant deformation of the tool was also observed during welding which caused bulging of the shoulder with an increased cone angle of the pin.