Investigation of the safety evaluation method of piping system

Journal of Mechanical Science and Technology - Plumbing is necessary for boilers and heat exchangers and in buildings and power plants, including those that produce green energy. Further, among all...     

Blockchain Network Based Topic Mining Process for Cognitive Manufacturing

Wireless Personal Communications - Cognitive manufacturing has brought about an innovative change to the 4th industrial revolution based technology in combination with blockchain distributed...     

Associative Feature Information Extraction Using Text Mining from Health Big Data

Wireless Personal Communications - With the development of big data computing technology, most documents in various areas, including politics, economics, society, culture, life, and public health,...     

Dual Catalytic and Self-Assembled Growth of Two-Dimensional Transition Metal Dichalcogenides Through Simultaneous Predeposition Process

The recent introduction of alkali metal halide catalysts for chemical vapor deposition (CVD) of transition metal dichalcogenides (TMDs) has enabled remarkable two-dimensional (2D) growth. However, the process development and growth mechanism require further exploration to enhance the effects of salts and understand the principles. Herein, simultaneous predeposition of a metal source (MoO₃) and salt (NaCl) by thermal evaporation is adopted. As a result, remarkable growth behaviors such as promoted 2D growth, easy patterning, and potential diversity of target materials can be achieved. Step-by-step spectroscopy combined with morphological analyses reveals a reaction path for MoS₂ growth in which NaCl reacts separately with S and MoO₃ to form Na₂SO₄ and Na₂Mo₂O₇ intermediates, respectively. These intermediates provide a favorable environment for 2D growth, including an enhanced source supply and liquid medium. Consequently, large grains of monolayer MoS₂ are formed by self-assembly, indicating the merging of small equilateral triangular grains on the liquid intermediates. This study is expected to serve as an ideal reference for understanding the principles of salt catalysis and evolution of CVD in the preparation of 2D TMDs.     

Production of high porosity nanoparticles of cerium oxide in clay

Cerium oxide nanoparticles modified montmorillonite was obtained by interaction of a clay with (NH₄)₂Ce(NO₃)₆. The mean size of cerium oxide nanoparticles in clay was at 3.5 nm. The product was an amorphous solid and showed high permanent porosity and stability at high temperatures. The amorphous structure of the sample was proven by X-ray diffraction and electronic diffraction. The porous structure was studied by means of chemisorption and it was shown that samples calcined at 550 °C had S_BET = 239 m²/g; micropore volume = 0.1839 cm³/g; average pore diameter = 3.07 nm.     

Information Processing and Wireless Energy Harvesting in Interference-Aware Public Safety Networks

In a public safety environment, user equipments (UEs) located within the coverage area of evolved NodeB, relay network services to out-of-coverage UEs. However, relay UEs in public safety environments are typically energy constrained and cannot operate indefinitely without recharging. Radio frequency energy harvesting has been proposed as a solution for recharging wireless UEs. In this paper, we propose a scheme for extending the lifetime of a public safety network by wirelessly charging relay UEs. In addition, we propose a relay selection method considering the battery status of relay UEs. The proposed relay selection is defined as a bipartite graph matching problem and the optimal relay is obtained through matching games technique. The proposed scheme not only improves the network lifetime but also extend the network coverage. We also conduct system level simulations to evaluate the performance of the proposed scheme. Simulation results show that the overall performance of the system is improved in terms of achievable throughput and network lifetime.     

Dielectric loss in porous TiO2

The dielectric loss behavior of TiO₂ was characterized on samples of variable porosity and variable pore size. Pores were formed by two methods: varying the sintering temperature and by the addition of a spherical carbon porogen. Porosities varied from 5.9% to 59.3%. Dielectric loss increased with increasing pore volume in each case. However, dielectric loss increased at a slower rate for porogen induced pores. At equivalent pore volumes, pore surface area volumes were higher than those induced using the porogen. Dielectric loss behavior was shown to vary linearly with pore surface area. Our work demonstrates that large pores reduce free surface area and decrease dielectric loss when compared to similar samples with smaller pores. A new model of porous dielectric loss is proposed that characterizes materials based on generalized free surface area instead of porosity alone. Based on this model, we show that the relative loss of porous dielectrics depends critically on the pore surface area and the loss tangent of the parent dielectric.     

Characterisation and properties of geopolymer composites. Part 2: Role of cordierite-mullite reinforcement

Our previous research paper on geopolymer-mullite composites showed promising results on compressive strength and fire resistance. However, no improvement in thermal shock resistance was observed in the afore mentioned study. In this study, further attempts to improve thermal shock resistance of the geopolymer were explored. The research was performed by compositing a fly ash-based geopolymer with cordierite-mullite at 20, 40 and 60 wt% replacement. X-ray diffraction (XRD) of the cured geopolymer composite specimens showed the existence of cordierite, mullite, quartz, cancrinite and lazurite. It was found that compressive strength and strength retention after thermal exposure at 400 °C were improved in the geopolymer composite specimens, especially those with 20–40 wt% replacement. Upon further heating to 600 °C, all geopolymer specimens showed insignificant differences in compressive strength. Fire resistance was found to improve with increasing proportion of replacement contents.