[en] Dye-sensitized solar cells (DSSCs) based on gel polymer electrolytes is a promising photovoltaic application which has been developed to solve the problem of liquid electrolyte leakage and improving the stability of the DSSCs. With the aim of replacing these liquid electrolytes for the applications of DSSCs, in this research we have prepared and optimized gel polymer electrolytes (GPE) consisting of poly[1-vinylpyrrolidone-co-vinyl acetate] (P[VP-co-VAc]), potassium iodide (KI), iodine (I_2), ethylene carbonate (EC), propylene carbonate (PC) and 1-methyl-3-propylimidazolium iodide (MPIm"+I"−) ionic liquid. The highest ionic conductivity obtained for this system is 3.13 × 10"−"3 S cm"−"1 at room temperature. Fourier transform infrared (FTIR) studies confirmed the complexation of the P(VP-co-VAc)-based gel polymer electrolytes. These GPEs were then assembled into DSSCs with the configuration of glass/FTO/TiO_2/N3 dye/electrolyte/Pt/FTO/glass. The resultant DSSCs from P(VP-co-VAc)-based conducting gel electrolytes display power conversion efficiencies of 4.67% with maximum short circuit current density (j_s_c) of 11.98 mA cm"−"2, open circuit voltage (V_o_c) of 0.59 V and fill factor of 66% at 15 wt.% of 1-methyl-3-propylimidazolium iodide under standard light intensity of 100 mW cm"−"2 irradiation of AM 1.5 sunlight. Electrochemical impedance studies of the DSSCs were conducted and results indicate that the addition of MPIm"+I"− increases the recombination process of the excited electron with I_3"− in the electrolyte which leads to shortening of the electron lifetime of the DSSCs. The electrocatalytic activity of the DSSC has also been investigated using Tafel polarization studies

[en] Highlights: • A 62.7 kW PV plant is modelled for a demand of 175 kWh/d with 1% annual load growth. • The plant’s yield and losses are 1723 kWh/kW and 502 kWh/kW, respectively. • The plant’s maximum monthly mean efficiency is 13.85%. • Availability of 98.91–99.56% is achieved over the year. • The plant’s estimated life cycle emission rate is 50 gCO_2/kWh. - Abstract: This study presents detailed techno-economic and environmental impact assessment of a photovoltaic power system (PPS) for a small off-grid community. The PPS is designed to meet a community’s load demand of ∼63,900 kWh, with an annual load growth of 1% over a 25-year project lifespan. Its performance is assessed in terms of the power output, energy production, yield and losses, and the efficiency. Furthermore, detailed battery state of charge (SoC) and reliability analysis is presented. The paper uses the life cycle evaluation technique to analyse the system’s economic and environmental performances, using Bununu community in Bauchi State, Nigeria as a case study. Results show that the loss of energy probability and the availability of 0.44–1.09% and 98.91–99.56%, respectively, can be achieved with PPS sizes of 50–62.7 kW. In addition, the proposed PPS’s life cycle costs range from ∼48 to 49.5% of the values obtained for the diesel plant. The PPS’s life cycle emission rate is 50 gCO_2-eq/kWh, which is ∼7.9–8.7% of the diesel plant’s emission rates. The proposed PPS’s GWP ranges from 4307 to 5400 kgCO_2-eq. These outputs are evaluated by comparing them with some existing results in the literature, and can be useful for planning stand-alone PPS for remote locations around the world.

[en] Mononuclear gold complexes in zeolite NaY were synthesized from initially physisorbed Au(CH₃)₂(C₅H₇O₂) and characterized by X-ray absorption and infrared spectra recorded as the samples were exposed to flowing CO. X-ray absorption spectra demonstrate the formation of zero-valent gold nanoparticles during the CO treatment. Three new ν_CO bands grew in during this treatment, at 2070, 2033, and 2000 cm^-1, characteristic of carbonyls of Au⁰. Because the relative intensities of these bands decreased monotonically when the flow of CO was replaced by flowing He, it is inferred that they correspond to a single Au⁰(CO)₃ species, on low-coordinated Au atoms. This is the first example of an Au⁰(CO)₃ species

[en] Nondestructuve testing of P/M products is a promising field. Besides defectoscopy, the advantage of nondestructive measurements in porous media lies in a rapid and accurate evaluation of physical and mechanical properties, such as point-to-point porosity, degree of interparticle metallic contact, modulus of elasticity, ultimate tensile strength and anisotropy. On the basis of inline experimental results obtained on tungsten and molybdenum products, a working system of quality control has been evolved at Mishra Dhatu Nigam Limited, Hyderabad. (auth.)

[en] In recent years, Chemical-looping combustion (CLC) is increasingly being considered as a promising technology to increase the efficiency of carbon capture in coal-fired power plants and for reducing CO_2 emissions into the atmosphere. The char gasification step required in the CLC process when using solid fuels such as coal is slow and often incomplete, which limits the rate of fuel conversion. The concept of multi-staged fuel reaction is proposed as an improvement to the original CLC concept to address this issue. System-level simulations of the single-stage, two-stage and four-stage CLC processes are conducted in Aspen Plus using a plug flow reactor model for the gasification step to incorporate the reaction kinetics into the simulation. By varying the reactor size and examining the char conversion and net energy output, the optimum reactor size for each multi-stage configuration is determined. The effect of multi-staging on the exhaust composition is also investigated. The results of the simulations show that multi-staging allows the use of multiple smaller reactors with the same total volume without incurring any penalty on the net energy output. - Highlights: • Concept of multi-staged CLC is proposed to enhance char gasification in CLC. • A plug flow reactor model is used to incorporate the reaction kinetics. • Optimum reactor size for multi-stage CLC is determined. • The effect of multi-staging on the exhaust composition is investigated. • Multi-staging allows use of smaller reactors without penalty on net energy output.

No abstract available

[en] Pilgering is the critical operation in production of zircaloy fuel tubes. The in-going tube is required for feeding in pilgering and the outgoing pilger tube length is measured and is cut into required lengths and transferred to storage tank before sending for degreasing. The paper deals with the automation of the above operation carried out on the pilger mills of New Zircaloy Fabrication Plant (NZFP). This has helped in improving the quality of the pilgered tubes and productivity of the mill besides eliminating manual handling and cutting operations

[en] The incorporation of two different type of iodide salts in the quasi-solid polymer electrolyte (QSPE) has been reported previously to have the ability to enhance the electrical performance of the QSPE and photovoltaic performance in the application of dye-sensitized solar cells (DSSCs). In this research, potassium iodide (KI) and tetrapropylammonium iodide (Pr₄NI) salts were used as the mobile ions providers for the poly(1-vinylpyrrolidone-co-vinyl acetate) (P(VP-co-VAc)) based quasi-solid polymer electrolytes (QSPEs). Dual salt system utilizing these two different salts will show improvement in the performance of the QSPE since they have different size and other characteristics. The resultant QSPEs with the dual iodide salts system in this research show better ionic conductivity compared to the QSPE with a single type of salt. The QSPE samples were sandwiched between a mesoporous nanocrystalline TiO₂ coated fluorine-doped tin oxide (FTO) glass which works as the photoelectrode and a platinum (Pt) coated FTO as the counter electrode in order to form a functional P(VP-co-VAc)-based QSPE DSSC. Cells with either KI or Pr₄NI, with identical QSPE compositions, were able to reach efficiencies of only 2.11% and 1.71% respectively. Interestingly, the cell with the dual iodide salts system under certain composition could display power conversion efficiency (PCE) of 5.53% with maximum short circuit density (J_sc) of 14.07 mA cm⁻², open circuit voltage (V_oc) of 0.60 V and a fill factor of 65% under standard light intensity of 100 mW cm⁻² irradiation of AM 1.5 sunlight. The cells have also been studied under different illumination condition and it was found that the overall photocurrent density of the cells is not only limited by the charge diffusion inside the QSPE samples. Electrochemical impedance studies of these cells have been studied to understand more on the electrical properties of the DSSCs. Tafel measurements which were carried out with two symmetrical Pt electrode has also been studied and shows that the dual salt system has higher electrocatalytic activity.

[en] Recent studies have indicated that the occurrence of the maxima of coronal mass ejection (CME) rate and sunspot number (SSN) were nearly two years apart. We find that the two-year lag of CME rate manifests only when the SSN index is considered and the lag is minimal (two-three months) when the sunspot area is considered. CMEs with speeds greater than the average speed follow the sunspot cycle much better than the entire population of CMEs. Analysis of the linear speeds of CMEs further indicates that during the descending phase of the solar cycle the loss of magnetic flux is through more frequent and less energetic CMEs. We emphasize that the magnetic field attaining the nonpotentiality that represents the free energy content, rather than the flux content as measured by the area of the active region, plays an important role in producing CMEs.

[en] Novel gel polymer electrolytes (GPEs) are prepared using poly(vinylidene fluoride-co-hexafluoro propylene) copolymer (PVdF-HFP) and polyethylene oxide (PEO) in presence of fumed silica nanofiller with the designated system of PVdF-HFP:PEO:EC:PC:NaI:SiO₂:I₂. GPEs are examined using electrochemical impedance spectroscopy (EIS) and the highest ionic conductivity of 8.84 mS cm⁻¹ is achieved after incorporation of 13 wt.% of fumed silica (SiO₂). Temperature-dependent ionic conductivity study confirms that GPE system follows Arrhenius thermal activated model. GPEs are characterized for structural studies using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. GPEs are used to fabricate dye-sensitized solar cells (DSSCs) and tested under 1 Sun irradiation, obtaining the highest energy conversion efficiency of 9.44% after the incorporation of 13 wt.% fumed silica. Cyclic voltammetry has been performed to analyse electrochemical properties of gel polymer electrolytes.