EPR study of Cu2+ in Na2O-NaF-B2O3-Bi2O3 glasses

Electron paramagnetic resonance (EPR) studies have been performed on the glass system (30–x) NaF-xNa₂O-50B₂O₃-20Bi₂O₃ doped with CuO as a paramagnetic probe. The calculated g values indicate that Cu²⁺ is in a tetragonally elongated octahedral co-ordination, and the Jahn-Teller character gives rise to anisotropic hyperfine structure. The spin-Hamiltonian parameters and -bonding parameter, ², are calculated. Varying the fluoride ion concentration and its effect on these parameters is also discussed.     

EPR, IR and DC conductivity studies ofxCuO-(100-x) Bi2O3 glasses

Glass systemxCuO-(100-x) Bi₂O₃ in the composition range 30–60 mol% of CuO is prepared by melt-quenching technique. The ESR spectra show no hyperfine splittings in parallel part but the peak to peak field width is found to vary with CuO content. The observedg effective values are found to vary with copper oxide. The absence of hyperfine splittings is due to inhomogeneous broadening. The observed IR spectra suggest the presence of Bi-O bonds. The structure is changing from [BiO₆] octahedral to [BiO₃] pyramidal units with increasing CuO concentration. D.C. electrical conductivity results indicate that the conduction is electron in nature and arises out of adiabatic hopping of polarons. The activation energy is found to be concentration and temperature dependent.     

Spectroscopic and transport studies of Cu2+ ion doped in (40 —x)Li2O—xLiF—60Bi2O3 glasses

The preparation of (40-x)Li₂O-xLiF-60Bi₂O₃ glassy system and spectroscopic and transport studies of this system are reported. IR results show that this glass consists of [BiO₃] units and indicate formation of Bi-F bonds with the addition of LiF. From the ESR spectra of Cu²⁺ ion, the effectiveg values are found to vary slightly with increasing concentration of fluorine ion. The optical absorption peak corresponding to Cu²⁺ increased linearly with increasing concentration of LiF between 620 nm and 728 nm except at 2.5 mole% of LiF where its value is 729 nm. This peculiar behaviour is attributed to the varying structural coordination of fluorine as the concentration of lithium fluoride is increased. The ionic conductivity measurements indicate that the conduction is due to adiabatic hopping of polarons and the activation energies are found to be temperature and concentration dependent     

Hierarchical fuzzy-based Quality of Experience (QoE)-aware application placement in fog nodes

Fog computing or a fog network is a decentralized network placed in between data source and the cloud to minimize the network latency issues and thus support in-time service delivery, of Internet of Things (IoT) applications. However, placing computational tasks of IoT applications in fog infrastructure is a challenging task. State of the art focuses on quality of service and quality of experience (QoE) based application placement. In this article, we design hierarchical fuzzy based QoE-aware application placement strategy for mapping IoT applications with compatible instances in the fog network. The proposed method considers user application expectation parameters and metrics of available fog instances, and assigns the priority of applications using hierarchical fuzzy logic. The method later uses Hungarian maximization assignment algorithm to map applications with compatible instances. The simulation results of the proposed policy show better performance over the existing baseline algorithms in terms of resource gain (RG), processing time reduction ratio (PTRR), and similarly network relaxation ratio. When considering 10 applications in the fog network, our proposed method simulation results show 70.00%, 22.44%, 37.83% improvement in RG, and 28.46%, 37.5%, 23.07% improvement in PTRR, when compared with QoE-aware, randomized, FIFO algorithms, respectively.