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91.
Glasses of the 33.5Li2O-66.5P2O5-xV2O5 (mol. %) system with (0 ≤ x ≤ 5) were prepared by the normal melting and annealing technique. Their physical and spectroscopic properties such as X-ray powder diffraction (XRD), density, infrared spectroscopy and electrical conductivity were investigated. The composition dependent density shows an initial decrease at 0.1 mol.% of V2O5 followed by an increase in density with further addition of the V2O5 content. The structure of these glasses has been studied by recording the Fourier-transform infrared spectroscopy (FTIR) over the range 400–1800 cm?1. Vibrational modes are assigned to different types of phosphate groups in the glass network. The temperature (333–452 K) and composition dependence of direct current (DC) electrical conductivity were measured. The electric conductivity is observed to increase with the first addition of vanadium oxide reflecting the presence of V4+ions that take part within modifying positions in the glass network .Then, the electric conductivity is found to decrease with the further increase in the content of V2O5 up to 5 mol.% reflecting the formation of V5+ions that take part as network forming positions in the glass network. The variations in density and electrical conductivity with V2O5 content are discussed in terms of changes in the glass structure. 相似文献
92.
S. Shamsuddin S. N. Supardan Abdel-Baset M. A. Ibrahim A. K. Yahya 《Journal of Superconductivity and Novel Magnetism》2014,27(5):1229-1234
Sr doping in the charge-ordered compound Nd0.3La0.2Ca0.5?x Sr x MnO3 has been systematically studied to examine its effect on ultrasonic velocity and elastic moduli as well as magnetic and electrical transport properties. DC electrical resistivity, ρ and AC susceptibility, χ′ measurements showed all samples exhibit metal-insulator (MI) behavior accompanied by ferromagnetic-paramagnetic (FM-PM) transition where the MI transition temperature, T MI and FM-PM transition temperature, T C increased with Sr content indicating the enhancement of double-exchange mechanism. Analysis of the resistivity change with respect to temperature, dlnρ/dT ?1 versus T indicates onset of charge-ordering (CO) state where its CO transition temperature, T CO decreased with Sr content indicating weakening of the CO state. On the other hand, both absolute longitudinal and shear velocities as well as elastic moduli measured at 80 K increased significantly with Sr doping indicating improvement in elastic properties, which is suggested to be due to the increase in formation of ferromagnetic domains. A longitudinal velocity anomaly characterized by a slope change around the vicinity of T CO was observed for all samples. The longitudinal elastic anomaly is attributed to the Jahn–Teller (JT) effect of Mn3+ ions where analysis of the anomaly using the mean-field theory suggests involvement of the JT effect in the samples, which transforms from dynamic to static type with decreasing temperature. The elastic anomaly shifted down from 222 K (x=0) to 205 K (x=0.05) indicating that the static JT effect was weakened with Sr content. 相似文献
93.
Abdullah A. AlZahrani Ibrahim Dincer 《International Journal of Hydrogen Energy》2021,46(27):13899-13907
The conventional hydrogen production methods, primarily steam methane reforming and coal gasification, produce massive amounts of greenhouse gas emissions which significantly cause impacts on the environment. An alternative hydrogen production method is high-temperature electrolysis using Solid Oxide Electrolyzer that combines both high conversion efficiency and saleable high purity hydrogen production. The produced hydrogen can feed the various industrial processes at different scales in addition to offering an environmentally friendly storage option. The scope of this paper is to examine the economic feasibility of this technology through the utilization of the exergoeconomic concept, which traces the flow of exergy through the system and price both waste and products. Therefore, a standalone solid oxide electrolyzer of a 1MWe is considered for hydrogen production using renewably generated electricity. Having the detailed exergy analysis conducted in earlier studies, the focus of this article is on the costing of each exergy stream to determine the exergy cost and the potential changes outcomes as a result of the system operating or design parameters optimization. It is found that the cost of hydrogen production through the modular high-temperature electrolyzer varies between $3-$9/kg with an average of about $5.7/kg, respectively. 相似文献
94.
Marwa M. Ibrahim 《中国化学工程学报》2021,40(12):225-236
To preserve the environment for civilization, we should remove the pollutants like toxic dyes by friendly and cost efficacious method. In this study, the effect of surfactants or mixed surfactants on physicochemical, optical and adsorption properties of ternary mixed oxide CeO2-ZrO2-Al2O3 (CZA) are investigated. The ternary mixed oxide CZA was prepared by surfactants or mixed surfactants assisted ultrasonic co-precipitation method. The physicochemical and optical properties are estimated by different techniques like XRD, TEM, EDX, FTIR, SBET and UV–Vis/DR. The CZAT and CZAC have hybrid shapes and high surface area. The adsorption properties of ternary mixed oxides adsorbents were characterized by sono-removing anionic dyes such as Congo red (CR) and Remazol red RB-133 (RR). The different factors like contact time, different dye concentrations and temperatures also studied. The kinetics and isotherms applications showed that, the adsorption process was followed pseudo second order kinetics and the Freundlich isotherm model. Also, the adsorption is spontaneous and endothermic process through the thermodynamic study. Finally, the results showed that the ternary mixed oxide nano-adsorbent (CeO2-ZrO2-Al2O3) is promising and functional materials for anionic dye sweep from wastewater. 相似文献
95.
Ibrahim I. T. Attallah K. H. Elsaid M. Fahmy M. H. Abo Zaid L. A. 《Radiochemistry》2019,61(2):220-225
Radiochemistry - Aspirin, one of nonsteroidal anti-inflammatory analgesic drugs, was labeled with 125I with a labeling yield of 85.5% under the following conditions: pH 9, 100 mg of the substrate,... 相似文献
96.
Abbas Syed Zeeshan Ibrahim Haroon Khan Majid 《Multimedia Tools and Applications》2021,80(17):26069-26091
Multimedia Tools and Applications - In this article, we have designed a new information confidentiality mechanism based on the combination of Blowfish encryption algorithm along with Henon and Chen... 相似文献
97.
In recent years, the interests of disassembly line have increased owing to economic reasons and the increase of environmental awareness. Effective line can provide many advantages in terms of economic aspect and it facilitates competition the companies with others. This study contributes to the relevant literature by a branch, bound and remember algorithm for disassembly line balancing problem with AND/OR precedence. The proposed exact solution method employs the memory-based dominance rule to eliminate the reduplicated sub-problems by storing all the searched sub-problems and to utilise cyclic best-first search strategy to obtain high-quality complete solutions fast. In this paper, minimising the number of stations is taken as the performance measure. The proposed methodology is tested on a set of 260 instances and compared with the mathematical model using CPLEX solver and five well-known metaheuristics. Computational results show that the proposed method is capable of obtaining the optimal solutions for all the tested instances with less than 0.1?seconds on average. Additionally, comparative study demonstrates that the proposed method is the state-of-the-art algorithm and outperforms the CPLEX solver and metaheuristics in terms of both solution quality and search speed aspects. 相似文献
98.
99.
In the current study, a solar tower–based energy system integrated with a thermal energy storage option is offered to supply both the electricity and freshwater through distillation and reverse osmosis technologies. A high‐temperature thermal energy storage subsystem using molten salt is considered for the effective and efficient operation of the integrated system. The molten salt is heated up to 565°C through passing the solar tower. The thermal energy storage tanks are designed to store heat up to 12 hours. The temperature variations in the storage tanks are studied and compared accordingly for evaluation. The effect of operating temperatures on the freshwater production and overall system efficiency is determined. About 24.46 MW electricity is generated in the steam turbine under sunny conditions. Furthermore, the storage subsystem stores heat during sunny hours to utilize later in cloudy hours and night time. The produced power decreases to 20.17 MW in discharging hours due to temperature decrease in the tank. The electricity generated by the system is then used to produce freshwater through the reverse osmosis units and also to supply electricity for the residential use. A total flowrate of 240.02 kg/s freshwater is obtained by distillation and reverse osmosis subsystems. 相似文献
100.
Medhat A. Nemitallah Ahmed A. Abdelhafez Asif Ali Ibrahim Mansir Mohamed A. Habib 《国际能源研究杂志》2019,43(14):7790-7822
The use of fossil fuel is expected to increase significantly by midcentury because of the large rise in the world energy demand despite the effective integration of renewable energies in the energy production sector. This increase, alongside with the development of stricter emission regulations, forced the manufacturers of combustion systems, especially gas turbines, to develop novel combustion techniques for the control of NOx and CO2 emissions, the latter being a greenhouse gas responsible for more than 60% to the global warming problem. The present review addresses different burner designs and combustion techniques for clean power production in gas turbines. Combustion and emission characteristics, flame instabilities, and solution techniques are presented, such as lean premixed air‐fuel (LPM) and premixed oxy‐fuel combustion techniques, and the combustor performance is compared for both cases. The fuel flexibility approach is also reviewed, as one of the combustion techniques for controlling emissions and reducing flame instabilities, focusing on the hydrogen‐enrichment and the integrated fuel‐flexible premixed oxy‐combustion approaches. State‐of‐the‐art burner designs for gas turbine combustion applications are reviewed in this study, including stagnation point reverse flow (SPRF) burner, dry low NOx (DLN) and dry low‐emission (DLE) burners, EnVironmental burners (including EV, AEV, and SEV burners), perforated plate (PP) burner, and micromixer (MM) burner. Special emphasis is made on the MM combustor technology, as one of the most recent advances in gas turbines for stable premixed flame operation with wide turndown and effective control of NOx emissions. Since the generation of pure oxygen is prerequisite to oxy‐combustion, oxygen‐separation membranes became of immense importance either for air separation for clean oxy‐combustion applications or for conversion/splitting of the effluent CO2 into useful chemical and energy products. The different carbon‐capture technologies, along with the most recent carbon‐utilization approaches towards CO2 emissions control, are also reviewed. 相似文献