F-LEACH: a fuzzy-based data aggregation scheme for healthcare IoT systems

The Journal of Supercomputing - Internet of Things (IoT) is an emerging paradigm that consists of numerous connected and interrelated devices with embedded sensors, exchanging data with each other...     

Ionization coefficient of monolayer graphene nanoribbon

A semi-analytical model for impact ionization coefficient of graphene nanoribbon (GNR) is presented. The model is derived by calculating probability of electrons reaching ionization threshold energy E_t and the distance travelled by electron gaining E_t. In addition, ionization threshold energy is semi-analytically modelled for GNR. During modelling, we justify our assumptions using analytical modelling and comparison with simulation. Furthermore, it is shown that conventional silicon models are not valid for calculation of ionization coefficient of GNR. Finally, the profile of ionization is presented using the proposed models and the results are compared with that of silicon.     

Direct extraction of Mo(VI) from sulfate solution by synergistic extractants in the rotation column

Direct extraction of molybdenum from sulfate solution with synergistic extractants (mixture of D₂EHPA and TBP) was studied in the rotation column. The influence of extractant concentration and initial pH of aqueous phase was studied in the bench scale experiments. The outcomes demonstrated that the synergistic solvent extraction enhances the constancy of the extracted complexes for transfer into the organic phase. In the continuous experiments, the effect of different operating parameters such as speed of agitation, inlet solvent flow rate and inlet aqueous flow rate on the holdup, mean drop size, drop size distribution, slip and characteristic velocities and extraction percentage were examined. Modified correlations were proposed for prediction of hydrodynamic parameters with consideration of reaction extraction condition in the rotation column. Furthermore, these correlations were compared with the experimental data. According to the results, the direct extraction of Mo (VI) from aqueous solution and sulfuric media with extraction efficiency of 90.4% was obtained at higher rotor speed (240 r·min^-1 rpm) in this column.     

Success criteria analysis in support of probabilistic risk assessment for nuclear power plants: application on SGTR accident

Success criteria analysis (SCA) bridges the gap between deterministic and probabilistic approaches for risk assessment of complex systems.To develop a risk model,SCA evaluates systems behaviour in response to postulated accidents using deterministic approach to provide required information for the probabilistic model.A systematic framework is proposed in this article for extracting the front line systems success criteria.In this regard,available approaches are critically reviewed and technical challenges are discussed.Application of the proposed methodology is demonstrated on a typical Westinghouse-type nuclear power plant.Steam generator tube rupture is selected as the postulated accident.The methodology is comprehensive and general;therefore,it can be implemented on the other types of plants and complex systems.     

Removal of iron from milk of lime to produce pure precipitated calcium carbonate

ABSTRACT

Milk of lime (MOL) suspension is widely utilized in many industries; however, in some of the applications, such as the production of precipitated calcium carbonate (PCC), the suspension must be of high purity and quality. In other words, the amounts of iron and magnesium should be so little so that the final PCC product would be of high quality. The effects of initial temperature, quicklime particle size, amount of initial solid present, agitation rate, and time on the recovery of hydrated lime and iron/magnesium reduction efficiency were investigated through a central composite design (CCD) of experiments. The iron reduction efficiency and the weight recovery of hydrated lime were obtained as 91% and 98.5%, respectively. The reduction of magnesium was not significant in this stage. Moreover, approximately the whole existing SiO₂ was eliminated.     

Novel composite nanofibers based on polyamide 66/graphene oxide- grafted aliphatic- aromatic polyamide: preparation and characterization

New polyamide 66/graphene oxide (GO)-grafted aliphatic-aromatic polyamide (polyamide-imide) (PAI) (PA66/GOF) composites nanofibers were successfully prepared via electrospinning method for the first time. An polyamide imide (PAI) was synthesized using polycondensation reaction from a dicarboxylic acid and a diamine based on 4,4′-(4,4′-isopropylidenediphenyl-1,1′-diyldioxy) dianiline, and characterized by ¹HNMR and FTIR. Morphological, structural, thermal and mechanical characteristics of the nanocomposite fibers were investigated by means of SEM, TEM, WAXD, DMTA and TGA techniques. Composites nanofibers of PA66/GO, PA66/PAI and PA66/GOF with smooth surface, uniform structure as well as with diameter ranging from 195 to 784 nm were obtained. The GO incorporation caused a reduction in the nanofibers diameters. The TEM images showed that the GO was well dispersed in the PA66 nanofibers without significant aggregation. An approximately 10 °C temperature increase in the glass transition temperature of PA66 was achieved by addition of 0.5 wt% of PAI, resulting from aliphatic-aromatic structure of PAI. By the TGA results, an increase about 40 °C was observed in the thermal stability of PA66/PAI composite nanofibers in comparison with that of pure PA66 nanofibers.     

Stochastic economic analysis of FACTS devices on contingent transmission networks using hybrid biogeography-based optimization

Electrical Engineering - Flexible AC transmission systems (FACTS) devices have advantages of enhancing AC system controllability and stability, increasing power transfer capability and relieving...     

Soil moisture estimation using land surface temperature and soil temperature at 5 cm depth

Soil Temperature (ST) data, obtained from either field works or satellite imagery, has frequently been studied for Soil Moisture (SM) estimation. However, a combination of ST data at different depths and soil surface temperature, i.e., Surface Radiometric Temperature (SRT) or Land Surface Temperature (LST), has not yet been well investigated for accurate SM prediction. In this study, an empirical model was first developed to estimate SM at 5 cm Depth (SM_5D) over areas with no or sparse vegetation cover using the field SRT and field ST data at 5 cm Depth (ST_5D). A Root Mean Square Error (RMSE) and a correlation coefficient (r) of 0.037 m³ m^?3 and 0.8 were obtained using this model, respectively. Then, the SRT was substituted by the LST obtained from Landsat thermal bands and ST_5D was estimated using the ST data collected at the nearest weather station to the study area by developing a regression equation. The second model demonstrated an RMSE and r of 0.035 m³ m^?3 and 0.71, respectively. Overall, it was concluded that the proposed models had high potential for SM estimation using the ST data at different depths collected in the field or acquired by optical satellites.     

Formation control of VTOL UAV vehicles under switching-directed interaction topologies with disturbance rejection

This paper addresses the adaptive formation control of a group of vertical take-off and landing (VTOL) unmanned aerial vehicles (UAV) with switching-directed interaction topologies. In addition, to tackle the adverse effect of disturbances, a couple of smooth bounded estimators are involved in the procedure design. Exploiting an extraction algorithm, we take advantage of the fully actuated rotational dynamics, to control the translational dynamics of each vehicle. We propose a distributed control scheme such that all vehicles track a desired reference velocity signal while keeping a desired prespecified formation. In this framework, the underlying topology of the agents may switch among several directed graphs, each having a spanning tree. The stability of the overall closed-loop system is proved through Lyapunov function. Finally, simulation results are given to better highlight the effectiveness of the proposed control scheme.     

Study of a Surface Plasmon Resonance Optical Fiber Sensor Based on Periodically Grating and Graphene

Silicon - In this paper an optical fiber sensor based on plasmonic resonance of graphene and periodically grating is designed and investigated. The proposed sensor consists of an optical fiber core...