An enhanced symbiosis organisms search algorithm: an empirical study

Many nature-inspired optimization algorithms have recently been proposed to solve difficult optimization problems where the mathematical gradient-based approaches could not be used. However, those approaches were often not tested on a proper set of problems. Moreover, statistical tests are sometimes not used to validate the conclusions. Therefore, empirical analyses of such approaches are needed. In this paper, a very recent nature-inspired approach, symbiosis organisms search (SOS), is investigated. A set of unbiased and characteristically different problems are used to study the performance of SOS. In addition, a comparison with some recent optimization methods is conducted. Then, the effect of SOS only parameter, eco_size, is studied, and the use of different random distributions is also explored. Finally, three simple SOS variants are proposed and compared to the original SOS. Conclusions are validated using nonparametric statistical tests.

     

Microscopic details of asphaltenes aggregation onset during waterflooding

We report detailed microscopic studies of asphaltenes aggregation onset during waterflooding of petroleum reservoirs. To achieve this objective, a series of simulations are performed on asphaltenic-oil miscibilized with water at high pressure and temperature through molecular dynamics. Results of this simulation onset are applicable to asphaltenes behavior in real crude oils. Our simulation results illustrate that the aggregation onset in waterflooding generally follows three sequential steps: (i) Asphaltene-water interaction; (ii) Water bridging; (iii) Face-to-face stacking. Then, asphaltene-water and water-water hydrogen-bonding network surround every aggregate boosting the intensity of aggregation onset. We intend to utilize such understanding of these details in our predictive and preventive measures of arterial blockage in oil reservoirs during waterflooding.     

Theoretical calculation simulation studies of ABV nuclear reactor coupled with desalination system

In this paper, research has been conducted on the floating type nuclear power plant named as ABV reactor which is designed for district heating, power, and sea water desalination by OKBM facility at Russia. This reactor was tested under different thermal loads during the designing phase, and three modules have been investigated. Theoretical calculations and simulation studies have been performed on these three modules having specifications as ABV‐6M with 47MW_th, ABV‐6 with 38MW_th, and ABV‐3 with 18MW_th.The results obtained from these modules have been calculated mathematically and verified by simulation. We have compared the originally derived data of ABV desalination system with our theoretical and simulation analysis. The results from two desalination techniques including RO and RO + MED have been calculated and are presented in this paper with details. The results obtained from both analysis show that the efficiency of ABV nuclear reactor desalination system increases with the decrease in corresponding water cost ratio. Copyright © 2015 John Wiley & Sons, Ltd.     

Theoretical investigation of plasma dynamical behavior and halo current analysis

In this paper, a novel system has been developed for plasma disruption conditions followed by downward vertical displacement. During the disruption, size and orientation of plasma decreases, which gives the halo current circulated around each contacting point in radial as well as in poloidal directions. Therefore, a new mathematical model has been developed, which gives the interaction forces of halo current, vertical, and radial plasma dynamical behavior (linear and nonlinear). This theoretical approach showed that the tokamak plasma has two connecting points in order to distinguish between the stable and unstable position. This model can particularly give the magnetic field change points and changing of flux, which are more convenient in order to discuss the static and tilting position of plasma behavior. Numerical techniques have been calculated in terms of plasma dynamical behavior, that is, Electromagnetic/plasma, Vertical Displacement Event (VDE) stages, and initial interaction between the forces under specific time interval. The objective of the research is to developed theoretical and computational model in order to investigate the dynamical behavior of plasma under disruption conditions. This is the novel method, and no work has been reported so far. Copyright © 2015 John Wiley & Sons, Ltd.     

Energy management of a hybrid photovoltaic system

This work describes a new control strategy for active energy flow in a hybrid photovoltaic (PV) system. The method introduces an online energy management by a hierarchical fuzzy controller between energy sources that consist of a photovoltaic panel (PVP), the battery and the load. The fuzzy logic controller has been developed for power splitting between PVP and battery, and it makes decision to choose the switching chain rules and corresponding controller. Simulation test results illustrate improvement in the operation's efficiency of online state of the switches and the battery's state of charge (SOC) has been maintained at a reasonable level. Copyright © 2010 John Wiley & Sons, Ltd.     

Synthesis,structure and optical properties of x(CuO)/(1−x)Ni(OH)2 [x=0, 0.1 and 0.3] nanocomposites

The x(CuO)/(1−x)Ni(OH)₂ [x=0, 0.1 and 0.3] nanocomposites were prepared by the hydrothermal method in the presence of the surfactant polyethylenglycol-10000 (PEG-10000). X-ray diffraction (XRD), infrared (IR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the as-prepared samples. The increase of the CuO content led to the increase of the crystallite size of both, the β-Ni(OH)₂ and the CuO. The increase in the crystallite size greatly affects the band gap energy of the as-prepared nanocomposites. The band gap energies of the x(CuO)/(1−x)Ni(OH)₂ nanocomposites were estimated by UV–vis spectroscopic method. UV–vis spectroscopic results showed an apparent decrease in the direct band gap energies. The x(CuO)/(1−x)Ni(OH)₂ [x=0, 0.1 and 0.3] nanocomposites show low band gap energies compared to the Ni(OH)₂ bulk materials. The enhanced optical properties lead to their possible use in photocatalytic and photovoltaic applications.     

Detection of pathogenic Escherichia coli strains in groundwater in the Yaoundé region (Cameroon,Central Africa)

This study was aimed at assessing the prevalence of pathogenic Escherichia coli strains, relative to the total count of E. coli, faecal coliforms and other heterotrophic mesophilic aerobic bacteria (HMAB) isolated in groundwater in the equatorial region of Cameroon (Central Africa). Bacteria were isolated using standard methods. Pathogenic E. coli strains were then identified using haemagglutination and antisera tests. The maximum abundance of HMAB, faecal coliforms and E. coli strains were 4.9 × 10⁶, 5.6 × 10³ and 1 × 10³ colony‐forming units (CFU)/100 mL, respectively. The count of pathogenic E. coli strains reached 3 CFU/100 mL. The counts of commensal and pathogenic E. coli strains underwent temporal and spatial fluctuations. In 21% of sampling sites, the abundance of faecal coliforms was significantly correlated to that of E. coli (P < 0.05). However, the isolated bacterial count was not significantly correlated to that of the pathogenic E. coli strains (P > 0.05). The bacteria abundance dynamics may be impacted by many interacting factors.     

An advanced VHDL‐AMS PiN diode model: towards simulation‐based design of power converters

This paper focuses on the modeling of a power PiN diode. The focal point basis is the dependence on temperature. The PiN diode remains a difficult device to model mainly during switching transients. An advanced PiN diode temperature‐dependent model is developed and implemented in VHDL‐AMS. Heterogeneous simulation scheme including the circuit wiring parasitic components, the probe effects and the dependent diode models is successfully simulated using SIMPLORER simulator. Experimental data of several commercial PiN diodes are compared to simulation results at different temperature levels. A good rate of consistency is found. Copyright © 2014 John Wiley & Sons, Ltd.     

Experimentally validated analytical modeling of diesel engine power and in-cylinder gas speed dynamics

Supercharged diesel engines are a key element in diesel powertrains that have been extensively modelled yet often without explainable mathematical trends. The present paper demonstrates the analytical modelling of in-cylinder gas speed dynamics and engine brake power. These analytical models provide explainable mathematical trends. In addition, they provide gear-shifting-based modeling because the model parameters can be adjusted to reflect different driving conditions without the need for gathering field data. An unprecedented sensitivity analysis was conducted on these developed models for simplifying them. They were validated using experimental data and the relative error of the developed model of the in-cylinder gas speed dynamics was 9.8%. The study demonstrates with 73% coefficient of determination that the average percentage of deviation of the simulated results from the corresponding field data on the engine brake power is 6.9%. The relative error of the developed model of the engine brake power is 7%. These values of relative error are an order of magnitude of deviation that is less than that of widely recognized models in the field of vehicle powertrain modeling such as the CMEM and GT-Power. These analytically developed models serve as widely valid models. Having addressed and corrected flaws in the corresponding models, such as the model of the in-cylinder gas speed dynamics presented in a key reference in this research area, these developed models can help in better analyzing and assessing the performance of diesel engines.