Synthesis,evolution and hydrogen storage properties of ZnV2O4 glomerulus nano/microspheres: A prospective material for energy storage

We present first study on ZnV₂O₄ glomerulus nano/microspheres synthesize by template free route to expose its hydrogen storage potential. Besides this the evolution of nano/microspheres has been investigated in detail. To reveal possible growth mechanism of these spheres, time-dependent experiments are performed. Reitveld analysis is taken into account for calculation of lattice parameters, crystallite size and strain. From our results, a correlation between lattice parameters and crystallite size is observed. The strain decreases with the increase in reaction time. Hydrogen storage measurement reveals potential of ZnV₂O₄ nanospheres as a prospective material for energy storage applications. These studies can open new avenue of research for hydrogen storage in spinel oxide materials.     

Facile Synthesis as well as Structural,Raman, Dielectric and Antibacterial Characteristics of Cu Doped ZnO Nanoparticles

Here, undoped and Cu doped ZnO nanoparticles(NPs) have been prepared by chemical co-precipitation technique. X-ray diffraction(XRD) results reveal that Cu ions are successfully doped into ZnO matrix without altering its wurtzite phase. The single wurtzite phase of ZnO is retained even for 10 wt% Cu doped ZnO sample. It is observed from the electron microscopy results that higher level of Cu doping varies the morphology of ZnO NPs from spherical to flat NPs. Moreover, the particle size is found to increase with the increase in Cu doping level. Raman spectroscopy results further confirm that Cu dopant has not altered the wurtzite structure of ZnO. Impedance spectroscopy results reveal that the dielectric constant and dielectric loss have increasing trend with Cu doping. Cu doping has been found to slightly decrease the bactericidal potency of ZnO nanoparticles.     

Reaction Time and Film Thickness Effects on Phase Formation and Optical Properties of Solution Processed Cu<Subscript>2</Subscript>ZnSnS<Subscript>4</Subscript> Thin Films

Copper-zinc-tin-sulfide (Cu₂ZnSnS₄ or CZTS) is a promising p-type semiconductor material as absorber layer in thin film solar cells. The sulfides of copper and tin as well as zinc and sulfur powders were dissolved in hydrazine. The effect of chemical reaction between precursor species, at room temperature, was assessed for 6 to 22 h. For 22 h reaction time, the effect of spin coated film thickness on the resulting composition, after annealing under N₂ flow at 500 °C for 1 h, was investigated. The morphology, composition, and optical properties of the annealed films were determined by means of x-ray diffraction, scanning electron microscope, and spectrophotometer studies. It was found that, for less than optimal reaction time of 22 h or film thickness below 1.2 µm, other ternary phases namely Cu₄SnS₄, Cu₅Sn₂S₇, and ZnS co-exist in different proportions besides CZTS. Formation of phase-pure CZTS films also exhibited a tendency to minimize film cracking during annealing. Depending on the processing conditions, the band gap (E _g) values were determined to be in the range of 1.55 to 1.97 eV. For phase-pure annealed CZTS film, an increase in the E _g value may be attributed to quantum confinement effect due to small crystallite size.     

Evaluation of nucleation in A-356 aluminum alloy by thermal analysis

Grain Refinement process is an important stage in production of aluminum castings. There is common question for all producer of aluminum castings that how they can be sure about the quality of nucleation. Thermal analysis is an important tool to answer this question. In this research, different types of inoculants were used to investigation of nucleation in A356 aluminum alloy. The cooling curve of each sample was recorded and by using a special computer program, the first derivative was calculated. By calculating zero curve and analyzing the cooling curve, it is possible to predict the quality of nucleation and calculation fraction of solids, latent heat and other information. The result of this research have shown that if maximum undercooling of nucleation was approximately 4 C, the quality of nucleation process will be more reliable.     

Effective and Comfortable Power Control Model Using Kalman Filter for Building Energy Management

In building environment energy management is a big problem in recent years. Several methods and proposals exist in the literature for energy management, but the trade-off between occupants comfort level and energy usage is still a major challenge and remained unresolved. In this paper, we propose power control model for comfortable and energy saving using fuzzy controller and Kalman filter. We have given focus in two directions simultaneously: first is to maximize the occupants comfort level and second is to control the usage of the power. To achieve these tasks, first we implement fuzzy logic to control the environment and second, we predict the consume power using Kalman filter. The parameters we consider are temperature, illumination and air quality. At the end of the paper we compare the power consumption results in case of prediction and with no prediction. The results proved the effectiveness of the proposed technique in obtaining the solution for the aforementioned problems.     

Efficient Joint Key Authentication Model in E-Healthcare

Many patients have begun to use mobile applications to handle different health needs because they can better access high-speed Internet and smartphones. These devices and mobile applications are now increasingly used and integrated through the medical Internet of Things (mIoT). mIoT is an important part of the digital transformation of healthcare, because it can introduce new business models and allow efficiency improvements, cost control and improve patient experience. In the mIoT system, when migrating from traditional medical services to electronic medical services, patient protection and privacy are the priorities of each stakeholder. Therefore, it is recommended to use different user authentication and authorization methods to improve security and privacy. In this paper, our prosed model involves a shared identity verification process with different situations in the e-health system. We aim to reduce the strict and formal specification of the joint key authentication model. We use the AVISPA tool to verify through the well-known HLPSL specification language to develop user authentication and smart card use cases in a user-friendly environment. Our model has economic and strategic advantages for healthcare organizations and healthcare workers. The medical staff can increase their knowledge and ability to analyze medical data more easily. Our model can continuously track health indicators to automatically manage treatments and monitor health data in real time. Further, it can help customers prevent chronic diseases with the enhanced cognitive functions support. The necessity for efficient identity verification in e-health care is even more crucial for cognitive mitigation because we increasingly rely on mIoT systems.     

Evaluation of Pd Nanoparticle-Decorated CeO<Subscript>2</Subscript>-MWCNT Nanocomposite as an Electrocatalyst for Formic Acid Fuel Cells

In this work, CeO₂-modified Pd/CeO₂-carbon nanotube (CNT) electrocatalyst for the electro-oxidation of formic acid has been investigated. The support CNT was first modified with different amounts (5–30 wt.%) of CeO₂ using a precipitation-deposition method. The electrocatalysts were developed by dispersing Pd on the CeO₂-CNT supports using the borohydride reduction method. The synthesized electrocatalysts were analyzed for composition, morphology and electronic structure using x-ray diffraction (XRD), scanning electron microscopy with energy-dispersive x-ray spectroscopy (SEM/EDX), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA) techniques. The formation of Pd nanoparticles on the CeO₂-CNT support was confirmed using TEM. The activity of Pd/CeO₂-CNT and of Pd-CNT samples upon oxidation of formic acid was evaluated by using carbon monoxide stripping voltammetry, cyclic voltammetry, and chronoamperometry. The addition of moderate amounts of cerium oxide (up to 10 wt.%) significantly improved the activity of Pd/CeO₂-CNT compared to the unmodified Pd-CNT. Pd/10 wt.% CeO₂-CNT showed a current density of 2 A mg^?1, which is ten times higher than that of the unmodified Pd-CNT (0.2 A mg^?1). Similarly, the power density obtained for Pd/10 wt.% CeO₂-CNT in an air-breathing formic acid fuel cell was 6.8 mW/cm² which is two times higher than Pd-CNT (3.2 mW/cm²), thus exhibiting the promotional effects of CeO₂ to Pd/CeO₂-CNT. A plausible justification for the improved catalytic performance and stability is provided in the light of the physical characterization results.     

Multiobjective optimization of microalgae (Chlorella sp.) growth in a photobioreactor using Box‐Behnken design approach

This study investigates a parameter optimization approach to maximize the specific growth rate of the Chlorella vulgaris microalgae species, its biomass productivity, and CO₂ capture rate. For this purpose, the Box‐Behnken experimental design technique is applied with temperature, nitrogen to phosphorus ratio, and light‐dark cycle per day, as the growth controlling parameters. For each response, a quadratic model is developed separately describing the algal specific growth rate, biomass productivity, and CO₂ capture rate, respectively. The maximum specific growth rate of 0.84 d^?1 is obtained at 25 °C, with a nitrogen to phosphorus ratio of 3.4:1, and light‐dark cycles of 24/0 h. Maximum biomass productivity of 147.3 mg L^?1 d^?1 is found at 30 °C, with a nitrogen to phosphorus ratio of 3:1, and light‐dark cycles of 12/12 h. In addition, the maximum CO₂ capture rate of 159.5 mg L^?1 d^?1 is also obtained at 30 °C, with a nitrogen to phosphorus ratio of 4:1, and light‐dark cycles of 23/1 h. Finally, a multi‐response optimization method is applied to maximize the specific growth rate, biomass productivity, and CO₂ capture rate, simultaneously. The optimal set of 30 °C, a nitrogen to phosphorus ratio 3:1, and light‐dark cycles 16/8 h, provide the maximum specific growth rate of 0.66 per day, biomass productivity of 147.6 mg L^?1 d^?1, and CO₂ capture rate of 141.7 mg L^?1 d^?1.

     

CFD simulation of chemical reaction between sulfur dioxide and water in a venturi scrubber

ABSTRACT

The use of fossil fuel, i.e., coal, was first initiated in 1880s for electricity generation. It was used extensively worldwide due to its cheap rate. Consequently, there is an adverse effect on the environment that results in a climate change. Many industries were working on cleaning flue gases emitted from coal power plants according to Environmental Protection Agency (EPA) standards by using different scrubbing technologies and venturi scrubber is one of them having ability to remove particulates and toxic gases simultaneously. Industries were using computational fluid dynamics (CFD) techniques to fully understand the gases behavior inside scrubbing technologies prior employed in the project. This research represents CFD simulation to study abatement process of sulfur dioxide through chemical reaction with water in a venturi scrubber. Parameters such as mass concentration of sulfurous acid formation, sulfur dioxide and water mass content distribution inside venturi scrubber were analyzed. The sulfur dioxide removal efficiency was also investigated. The results show that water mass content distribution was greatly influenced by sulfur dioxide mass flow rates. Desulfurization efficiency depreciates with an increase in sulfur dioxide mass flow rate, whereas efficiency increases with accession in liquid to gas ratio. Maximum sulfur dioxide removal was observed at lower sulfur dioxide concentration comparatively to higher concentration of sulfur dioxide.