Investigation of Spatial Distribution of Hydrogen and Argon Ions and Effects of them on Aluminum Samples in a 2.5 kJ Mater Type Plasma Focus Device

In this work the effects of Hydrogen and Argon ions on Aluminum samples and the spatial distribution of the ions in 2.5 kJ SBUPF1 Mather type plasma focus device in different distance from the anode top have been investigated. For each gas the pressure and operation voltage have been determined to have maximum ion density. Aluminum samples were placed at different distances above the anode. Irradiated samples have been analyzed with SEM technique for morphological and surface study of samples. Melting and surface evaporation effects and generation of cracks were seen in these samples. The result of ions patterns on these samples can be used to determine ions spatial distribution on top of the anode region. The EDX spectroscopy and the SRIM calculations have been done to determine the composition of samples and the penetration depth of the ions in the samples respectively.     

A discrete model for prediction of radon flux from fractured rocks

Prediction of radon flux from the fractured zone of a propagating cave mine is basically associated with uncertainty and complexity. For instance, there is restricted access to these zones for field measurements, and it is quite difficult to replicate the complex nature of both natural and induced fractures in these zones in laboratory studies. Hence, a technique for predicting radon flux from a fractured rock using a discrete fracture network (DFN) model is developed to address these difficulties. This model quantifies the contribution of fractures to the total radon flux, and estimates the fracture density from a measured radon flux considering the effects of advection, diffusion, as well as radon generation and decay. Radon generation and decay are classified as reaction processes. Therefore, the equation solved is termed as the advection-diffusion-reaction equation (ADRE). Peclet number (Pe), a conventional dimensionless parameter that indicates the ratio of mass transport by advection to diffusion, is used to classify the transport regimes. The results show that the proposed model effectively predicts radon flux from a fractured rock. An increase in fracture density for a rock sample with uniformly distributed radon generation rate can elevate radon flux significantly compared with another rock sample with an equivalent increase in radon generation rate. In addition to Pe, two other independent dimensionless parameters (derived for radon transport through fractures) significantly affect radon dimensionless flux. Findings provide insight into radon transport through fractured rocks and can be used to improve radon control measures for proactive mitigation.     

Applying of LSSVM approach as a novel tool for accurate prediction of asphaltene inhibition efficiency

Asphaltene precipitation is one of critical problems for petroleum industries. There are different methods for inhibition of asphaltene precipitation. One of the common and effective methods for inhibition of asphaltene precipitation is utilizing asphaltene inhibitors. In this work, Least squares support vector machine (LSSVM) algorithm was coupled with simplex optimizer to create a novel and accurate tool for estimation of effect of inhibitors on asphaltene precipitation as function of concentration and structure of inhibitors and crude oil properties. To this end a total number of 75 measured data was extracted from the literature for training and testing of predicting model. The average absolute relative deviation (AARD), the coefficient of determination (R²) and root mean square error (RMSE) of total data for prediction algorithm were determined as 1.1479, 0.99406 and 0.61039. According to these parameters and graphical comparisons the LSSVM algorithm has potential to predict asphaltene precipitation in high degree of accuracy.     

Prediction of dynamic viscosity of n-alkanes at high pressures using a rigorous approach

An adaptive neuro-fuzzy interference system has been developed for estimating the dynamic viscosity of n-alkanes in a wide range of operating conditions. In this study, for the first time, a simple predictive model is proposed for viscosity prediction of n-pentane, n-octane, n-nonane, n-decane and dodecane at various pressures and temperatures, especially at high pressures, without needing to measurement or estimation of density. This tool predicts the dynamic viscosity of the n-alkanes as function of pressure, temperature and n-alkanes' molecular weight. The obtained results of the model were in an excellent agreement with experimental data with an acceptable coefficient of determination of 0.999 for both training and testing datasets. Moreover, the validity of the proposed model for viscosity trends prediction at various conditions was demonstrated and it showed a very good match with actual data. This model is simple to use and can be of massive evaluation for better understanding the behavior of fluids under reservoir conditions.     

ESIV: an end-to-end secure internet voting system

Nowadays, with the growing popularity of e-Government services, security of client platforms and violation of citizen e-rights are of great concerns. Since Internet-voting protocols have no control over voter-side platforms, bribery/coercion and breaching vote’s privacy and voter’s anonymity are feasible. In fact, the voter-side platform (voter’s PC) is easily vulnerable to malicious software (cyber-attacks) and can totally breach security of the entire voting protocol. We have proposed ESIV: an end-to-end secure internet-voting system that highly guarantees: voter and server-side platform’s security, verifiability, fairness, resistance to bribery/coercion and voting authorities collusion besides simultaneous election support while preserving eligibility, anonymity, privacy and trust. In addition, we utilize Java Card 3 technology as an independent secure web-server which is connected directly to network in order to send/receive HTTP(S) requests using high-speed interfaces. This technology brings about independence from utilizing any trusted device at voter-side and provides end-to-end security. Finally, an implementation of ESIV is presented and ESIV security features are evaluated.     

Energy and Angular Distributions of High-Energy Nitrogen Ion of Plasma Focus Device SBUMTPF1 by Aluminum Filters Coated on Polycarbonate Nuclear Track Detector

The main objective of this study is to determine energy distribution and angular distribution of nitrogen ions produced in plasma focus device SBUMTPF1 measured with polycarbonate nuclear track detector. To achieve this goal, the detectors were covered by different thicknesses of aluminum filters, using physical vapor deposition method and by coated films the anisotropic distribution of nitrogen ions was investigated. For determination of nitrogen ion energy distribution, the detectors were settled in the distance of 21.5 cm and in 0° angle to the end of anode and for determination of angular distribution of ions, 1,200 nm aluminum coated detectors in 10 cm distance and at angles of 0°, 15°, 30°, 45° and 60° with respect to the anode were used. For better ion detection, a pinhole of 200 μ was used for energy distribution measurement and a pinhole of 500 μ was used for angular distribution measurement. In all experiments electrical discharges were done in the voltage of 23 ± 0.5 kV and nitrogen with the pressure of 0.5 mbar was used as working gas. By using SRIM code, the ranges of nitrogen ions were measured in aluminum. SBUMTPF1 angular distribution curve show a peak at a 30° angle against the anode axis. Besides, the suitable thickness range of aluminum filter for data registration was from 1,240 to 2,620 nm.     

Experimental investigation the effect of nanoparticles on micellization behavior of a surfactant: Application to EOR

Chemical stimulation such as surfactant flooding in petroleum reservoirs makes efforts to produce remained oil and improve sweep efficiency by means of different phenomena such as lowering interfacial tension and wettability alteration of reservoir rock. Implementing concentration of surfactant through surfactant flooding is one of the big challenges while interfacial tension between surfactant solution and oil after certain concentration involves little changes such as critical micelle concentration (CMC). This article highlights the effect of nanosilica on CMC of Zyziphus Spina Christi, as sugar-based surfactant, in aqueous solutions for enhanced oil recovery and reservoir stimulation purposes. A conductivity approach was selected to assess the CMC of the introduced surfactant in aqueous solution at 25°C. The influence of nanosilica concentrations on CMC variation of introduced surfactant is considered. It is found that CMC of introduced surfactant decreased while the concentration of the nanosilica increased. Results from this study can aim in optimum condition selection of surfactant flooding as an enhanced oil recovery ends.     

Five-leg converter topology for wind energy conversion system with doubly fed induction generator

In this paper, application of a five-leg converter in Doubly Fed Induction Generator (DFIG) for Wind Energy Conversion Systems (WECS) is investigated. The five-leg structure and its PWM control are studied and performances are compared with the classical six-leg topology. The main drawback of five-leg converter with respect to the six-leg back-to-back converter is the need to increase the dc-link voltage for the same operation point, i.e. the same powers in case of WECS. So, different methods for the reduction of the required dc-link voltage in the five-leg case are studied. The five-leg converter is used to replace the conventional six-leg one, with the same ability. For the performance evaluation of this structure and its fully digital controller in a more realistic and experimental manner, Hardware in the Loop experiments is carried out. It is shown that efficient control of active and reactive powers and dc-link voltage is performed. Hardware in the Loop results demonstrate the high performance of the proposed fully digital control which is implemented on an Altera FPGA target.     

Evaluation of effective parameters for the synthesis of poly(propylene fumarate) by response surface methodology

Poly(propylene fumarate) (PPF) is an unsaturated linear polyester, which was synthesized for potential applications in filling skeletal defects. The synthesis was carried out according to a two‐step polymerization reaction. In this research, a functional relationship among three reaction factors [temperature, reaction time, and stoichiometry of the monomers] in the PPF synthesis was established by responses of the surface methodology/central composite design (CCD). After that, on the basis of the responses of CCD [increasing intensity ratio of the C? H/O? H peaks in Fourier transform infrared (FTIR) spectra], designed substances were synthesized and analyzed by FTIR spectroscopy. The synthesized PPF, based on the optimized synthesis conditions from CCD, had a high molecular weight, low hydroxyl group content, and optimum viscosity. According to the CCD response, the best product was obtained through with a molar ratio of diethyl fumarate/propylene glycol/ZnCl₂/hydroquinone of 1:3.5:0.01:0.002 and a 17‐h reaction time at 140°C. Eventually, the synthesized PPF was characterized by FTIR spectroscopy, NMR, and gel permeation chromatography analyses. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40932.