Effect of Temperature on Hydraulic Parameters of Cable-In-Conduit-Conductor of SST-1

Stable operation of superconducting magnets depend critically on the balance of heat deposition rate versus heat extraction rate by the cryo-coolant. Thus, the mass flow rate of the coolant in case of force-flow cooled superconducting magnet with Cable-In-Co-nduit-Conductor (CICC) construction becomes an important factor for optimum stability of magnets. The Toroidal and Poloidal Field magnets of Steady-state Superconducting Tokamak-1 (SST-1) is made of superconducting CICC with a void fraction of 40 %±2 %. For adequate cooling of magnets, supercritical helium at 4 bar and 4.5 K is forced-flown through the voids. Effect of temperature on mass flow rate and pressure drop in SST-1 CICC is studied in a 7 m long piece wound helically. The experimental friction factor of the CICC is also measured at different temperatures and flow rates and is compared with the standard Katheder equation and Tada equation. Also, based on the new findings obtained from the experimental results, the dimensionless Reynolds number has been slightly modified. This new number is used to propose a modified Katheder correlation for the friction factor in CICCs similar to that of SST-1.     

Application of thermophilic temperatures,low hydraulic retention times and high recycling of de-gassed effluent for higher biohydrogen production

This study investigated the external operational factors that would reduce the thermodynamic constrains preventing the simultaneous achievement of high hydrogen productivities (HPs) and hydrogen yields (HYs) in the bioreactor. At hydraulic retention time (HRT) of 1, the maximum HPs and HYs achieved was 35 L H₂/h and 3.91 mol H₂/mol glucose, respectively. At this stage, the bacterial granules occupied approximately 75% of the bioreactor and consisted of the settled biomass density of 40.6 g/L (settled granule bed height = 13.8 cm). The formation of bacterial granules improved the bioreactor performance and resulted in higher substrate conversion efficiency (95%), nutrient influent (7.5 L/h) and de-gassed effluent recycle rates (3.5 L/min). In conclusion, this study demonstrated that high nutrient influent and high de-gassed effluent recycle rates reduced the thermodynamic constrains preventing the achievement of higher H₂ productivities in the bioreactor system.     

Studies of dielectric and electrical properties of a new type of complex tungsten bronze electroceramics

A polycrystalline ceramic with a new type of complex tungsten-bronze type structure, having a general formula K₂Ba₂Nd₂Ti₄Nb₄W₂O₃₀ has been prepared using a high temperature solid-state reaction route after optimizing the calcinations conditions on the basis of thermal analysis results. The material has been characterized by different experimental techniques. The formation of the compound has been confirmed using X-ray diffraction analysis. Dielectric properties (ε_r and tanδ) of the compound as a function of temperature at different frequencies have been carried out. Temperature dependence of dielectric constant indicates the presence of ferroelectric phase transition well above the room temperature. Complex impedance spectroscopic analysis has been carried out as a function of frequency at different temperatures to establish some correlation between the microstructure and electrical properties of the material. The nature of frequency dependence of ac conductivity obeys the Jonscher’s power law. The dc conductivity calculated from the ac conductivity spectrum shows the negative temperature coefficient of resistance behavior like a semiconductor.     

Influence of iron deficiency on electric and magnetic behavior of Ho doped BiFeO3 electroceramic

The effect of iron deficiency for the improvement of multiferroic properties of Ho doped BiFeO₃ ceramics (BiHo_XFe_1?XO₃ for x = 0, 0.05, 0.1 and 0.15) prepared by conventional solid state reaction route were investigated carefully. As pure BiFeO₃ exhibited antiferromagnetism, lossy ferroelectric (P–E) hysteresis loop and low dielectric constant value so, device integration is significantly hindered due to the presence of impurity phases associated with it. However, suitable variation of metal ion concentration in Ho doped BiFeO₃ significantly enhanced both ferroelectric and ferromagnetic properties of the samples. Therefore, increase of Ho concentration certainly favors for suppression of impurity phases in rhombohedral (R3c) structure of BiFeO₃ along with no structural transformation. On the other hand, increase of iron deficiency may suppress transformation of Fe from Fe³⁺ to Fe²⁺ as a result, the dielectric constant value of the sample increases along with large reduction of leakage current behavior.     

Pulse Reverse Electrodeposition of Cu-SiC Nanocomposite Coating: Effects of Surfactants and Deposition Parameters

Cu-SiC nanocomposite coatings have been deposited from an aqueous sulfate electrolyte using the technique of pulse reverse electrodeposition both in the absence and presence of three different types of surfactants, anionic, cationic, or nonionic. The effects of different electrodeposition parameters on some properties of the coatings have been studied. In all cases, it has been observed that the surface roughness, hardness, and resistivity increase with the increase in cathodic current density. However, they have been observed to decrease with the increase in anodic current density and the anodic current time. The variation in the amount of incorporated reinforcement with different deposition parameters has been observed to be dependent on the nature of the surfactant used. In the presence of cationic and nonionic surfactant, a noticeable increase in the amount of incorporated reinforcement and hardness has been observed. Samples prepared under higher anodic current density have been observed to possess lower stress, but intense texture. An increase in cathodic current density has been observed to decrease the extent of texturing.     

Recent advances in indium metallurgy: A review

The by-products of zinc refineries are used as the primary mineral resources for the commercial production of indium. The discarded LCDs containing adequate amount of indium is rather worth as its secondary resources compared to the by-products of zinc refineries. Mining and recycling rates of indium, respectively from minerals and waste LCDs are in progress to meet its huge demand. Recycling of the LCDs has been dominating over mining, as presently 480t of indium are produced annually from mining, however, that of 650t annually from recycling. Different aspects of the extractive metallurgy of indium are summarized in this review paper.     

Mechanistic study of Al electrodeposition from EMIC–AlCl3 and BMIC–AlCl3 electrolytes at low temperature

Aluminum was electrodeposited from two different ionic liquid electrolytes namely; 1-ethyl-3-methylimidazolicum chloride and AlCl₃ (EMIC–AlCl₃) and 1-butyl-3-methylimidazolium chloride (BMIC–AlCl₃) at 90 ± 2 °C. Nodular morphology of aluminum was obtained at the copper substrate. To evaluate the reaction mechanism, chronoamperometric study was adopted. From the chronoamperometric analysis, it was observed that the reaction was controlled by instantaneous three-dimensional diffusion process. The diffusion coefficient (D) of Al₂C₇⁻ was found to be 5.2–6.6 × 10⁻¹¹ m² s⁻¹ and 2.2 × 10⁻¹¹ m² s⁻¹ for EMIC–AlCl₃ and BMIC–AlCl₃ ionic liquid electrolytes, respectively. The nuclei density of electrodeposited aluminum on the copper was also confirmed by scanning electron microscope wherein uniformly distributed aluminum nodules were observed.     

Delay-discretization-based sliding mode $$H_{\infty }$$ load frequency control scheme considering actuator saturation of wind-integrated power system

This paper investigates the combined effect of actuator saturation and time-delay on load frequency control (LFC) of a wind-integrated power system (WIPS). Actuator saturation is represented in two different approaches such as polytopic and sector bounding. Delay-discretization-based sliding mode \(H_{\infty }\) control approach is proposed to design a novel LFC scheme. The proposed control scheme requires present as well as delayed states information as input to the controller. This requirement of control scheme is fulfilled by adopting a finite known delay. This finite known delay used in controller design is discretized into delay intervals. Lyapunov–Krasovskii functional is defined for each delay interval, and \(H_{\infty }\) stabilization criteria for the closed loop WIPS are derived in linear matrix inequality framework using Wirtinger-based inequality. The proposed control scheme is tested by considering a numerical example of two-area WIPS.