Prediction of critical total drawdown in sand production from gas wells: Machine learning approach

Sand production is a critical issue in petroleum wells. The critical total drawdown (CTD) is an essential indicator of the onset of sand production. Although some models are available for CTD prediction, most of them are proven to lack accuracy or use commercial software. Furthermore, the previous correlations have not studied the trend analysis to verify the correct relationships between the parameters. Therefore, this study aims to build accurate and robust models for predicting CTD using response surface methodology (RSM) and support vector machine (SVM). The RSM is utilized to obtain the equation without using any software. The SVM model is an alternative method to predict the CTD with higher accuracy. This study used 23 datasets to develop the proposed models. The CTD is a strong function of the total vertical depth, cohesive strength, effective overburden vertical stress, and transit time with correlation coefficients (R) of 0.968, 0.963, 0.918, and −0.813. Different statistical methods, that is, analysis of variance (ANOVA), F-statistics test, fit statistics, and diagnostics plots, have shown that the RSM correlation has high accuracy and is more robust than correlations reported in the literature. Moreover, trend analysis has proven that the proposed models ideally follow the correct trend. The RSM correlation decreased the average absolute percent relative error (AAPRE) by 12.7% compared to all published correlations' AAPRE of 22.6%–30.4%. The SVM model has shown the lowest AAPRE of 6.1%, with the highest R of 0.995. The effects of all independent variables on the CTD are displayed in three-dimensional plots and showed significant interactions.     

Tocotrienols for normalisation of hepatic echogenic response in nonalcoholic fatty liver: a randomised placebo-controlled clinical trial

Background

Increased density of fast food restaurants is associated with increased prevalence of obesity in developed countries. However, less is known about this relationship in developing countries undergoing rapid urbanization and how differences in neighbourhood income affect the patronage of fast food outlets. The purpose of the study is to explore the differences in fast food preferences, perceptions, and patronage between Indians living in high- and low-income neighbourhoods.

Methods

This cross-sectional study recruited 204 men and women (35 to 65 years in age) from high- and low-income neighbourhoods who completed a questionnaire on fast food consumption. The questionnaire asked participants to define fast food and to provide reasons for and frequency of visits to fast food restaurants. The differences were analyzed using Chi square and t-tests for categorical and continuous variables, respectively.

Results

Participants from a high-income neighbourhood were more likely to perceive Western -style fast food as fast food, while people from the low-income neighbourhood were more likely to identify food sold by street vendors as fast food (p <0.001). Furthermore, compared to participants from the high-income neighbourhood, people from the low-income neighbourhood were more likely to report buying food from street vendors while less likely to dine out at both fast food and non-fast food restaurants (p<0.001). Although the high-income neighbourhood group was more likely to report enjoying eating at fast food restaurants than their low-income neighbourhood counterparts, there were no significant differences in the reasons for visiting fast food restaurants (convenience, price, social enjoyment, and quality of meals) between the two groups. Both groups preferred home cooked over restaurant meals, and they recognized that home cooked food was healthier.

Conclusions

Overall, consumption of fast food was low. People from a high-income neighbourhood dined out more frequently and were more likely to perceive Western-style food as fast food compared to their counterparts from the low-income neighbourhood.     

Indole Alkaloids of Alstonia angustifolia var. latifolia as Green Inhibitor for Mild Steel Corrosion in 1 M HCl Media

The inhibition effect of mild steel (MS) corrosion in 1 M HCl was studied by the addition of indole alkaloids (crude) isolated from Alstonia angustifolia var. latifolia (A. latifolia) leaves at 303 K. Potentiodynamic polarization, impedance spectroscopy, scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) analyses were used for this study. Results show that the isolated alkaloid extract of A. latifolia is a good inhibitor and exhibited maximum inhibition efficiency (above 80%) at concentrations between 3 and 5 mg/L. Polarization measurements indicated that the inhibitor does not alter the mechanism of either anodic or cathodic reactions and acted as mixed-type inhibitor. The inhibition efficiencies of both electrochemical techniques are found to be in good agreement and adsorption of inhibitor follows Langmuir isotherm. Adsorption of inhibitor over metal surface was well supported by the SEM studies, while FTIR studies evidenced the presence of indole alkaloids as green inhibitor that reduces the rate of corrosion.     

Investigation of Co-Substituted Nanosized Mn2Y-Hexaferrites Synthesized by Sol-Gel Autocombustion Method

The structural and electrical properties of Co-substituted and nano-sized Y-type hexagonal ferrites have been investigated in the present work. The samples with chemical composition Ba₂Co _x Mn_2?x Fe₁₂O₂₂ (x = 0.0, 0.5, 1.0, 1.5, 2.0) were prepared by sol-gel autocombustion method. The powdered samples and pellets were sintered simultaneously at 1000 °C for 5 h and characterized by means of DTA/TGA, FTIR spectroscopy, x-ray diffraction (XRD), field emission gun scanning electron microscopy, and energy dispersive x-ray spectroscopy. The XRD analysis confirms that the investigated ferrites have single phased Y-type hexagonal structure without showing any impurity phase. Lattice constants (a and c), cell volume (V), crystallite size (D), and x-ray density (ρ _x ) have also been calculated from the XRD data. DC electrical resistivity is measured within the temperature range of 30-100 °C for each sample and is observed to increase with increasing Co-substitution. The dielectric constant (∈) has also been measured which is observed to decrease with Co-substitution. Thus, high electrical resistivity and low dielectric constant make these materials suitable for multi-layer chip inductors and also for RF components and circuits.     

Synthesis and characterization of novel comb-type amphiphilic graft copolymers containing polypropylene and polyethylene glycol

Amphiphilic comb-type graft copolymers containing polypropylene (PP) and polyethylene glycol (PEG) have been prepared. Polypropylene-g-polyethylene glycol comb-type thermoplastic amphiphilic copolymers were synthesized by the reaction between chlorinated polypropylene and polyethylene glycol in the presence of a base via a “grafting to” technique. A series of graft copolymers containing PEGs with molecular weights of 600 and 2,000 Da in the range of 4–34 mol% PEG were obtained. The amphiphilic graft copolymers with PEG segments in range between 20 and 30 mol% PEG displayed good film properties with elongation at break 275–440%. The hydrophilicity of the amphiphilic copolymers increases with the increasing PEG content in the copolymer while the mechanical properties decrease. Therefore, PP-g-PEG2000 with PEG contents in the range of 20–30 mol% PEG should be useful for medical and industrial applications where good film properties are needed.     

One-step preparation of poly(NIPAM-pyrrole) electroconductive composite hydrogel and its dielectric properties

Conductive polymers and hydrogels are two of the hot prospect polymer types that are used for new stimuli responsive materials. In this study, one-step preparation of electroconductive composite hydrogels containing polypyrrole (PPy) and N-isopropylacrylamide (NIPAM) using free radical polymerization technique was achieved with N,N-methylenebisacrylamide as a crosslinker and ammonium peroxy disulphate (APS) as initiator, in mixture of water/isopropyl alcohol. The equilibrium swelling degree of the poly(NIPAM)-pyrrole) electroconductive composite hydrogel was 9.88 g of H₂O/g dry polymer. According to TGA results, the thermal stability of the prepared composite poly(NIPAM-PPy) conductive hydrogel (700°C) hydrogel is higher than that of pure poly(NIPAM) hydrogel (600°C). Furthermore, prepared samples were characterized by FTIR, and SEM analyzes. Later, the samples were pressured into pellets so that electrical impedance spectroscopy (EIS) measurements were taken between 10 and 10 MHz at room temperature. The dielectric constant value of composite poly(NIPAM-PPy) hydrogel at 10 Hz is almost 10 times higher than that of poly(NIPAM) hydrogel. Both samples' real and imaginary parts of dielectric constant decreased with increased frequency. Samples exhibited non-Debye relaxation since experimental data fit into dielectric model of Havriliak-Negami. Moreover, low frequency data yielded d.c. conductivity of the pure and composite samples as 3.74 × 10⁻¹¹ and 1.02 × 10⁻⁸ S/cm, respectively. Real part of impedance at low frequencies also points out ~10³ times lower resistance values at 10 Hz for composite poly(NIPAM-PPy) hydrogel. Therefore, EIS results support that electroconductive composite hydrogel fabrication was achieved using free radical polymerization technique.     

Voltammetric behavior of nicotine at pencil graphite electrode and its enhancement determination in the presence of anionic surfactant

The electrochemical oxidation of nicotine was studied in aqueous as well as micellar media at a pencil graphite electrode using cyclic, differential pulse and square-wave voltammetric techniques. The compound was oxidized irreversibly at low positive potentials in one (in acidic and neutral media) or two (in alkaline media) oxidation steps. The response was evaluated with respect to pH, scan rate, addition of surfactant and other variables. For analytical purposes, very resolved voltammetric peaks at +0.84 V (versus Ag/AgCl) were obtained in phosphate buffer at pH 7.0 containing 2 mM sodium dodecylsulfate using square-wave mode. The process could be used to determine nicotine concentrations in the range of 7.6–107.5 μM with a detection limit of 2.0 μM (0.33 mg L⁻¹). The proposed method was applied to the determination of nicotine in different brands of commercial cigarettes.     

Specific concerns of Pakistan in the context of energy security issues and geopolitics of the region

The global and regional energy security in future is not likely to be threatened as much by the shortage of resources as it is likely to be endangered by the disruption of supplies and availability of tradable resources: threatened by growing terrorism and geopolitical conflicts. Pakistan's geo-strategic position and its importance act to both influence and undermine its energy security issues. It has the potential to provide a corridor for regional energy trade but it is ranked among the top nations exposed to potential threat of terrorist attacks because of the consequences of its role in the major geopolitical expeditions of the recent past. The paper examines the concerns of Pakistan emanating from the regional and global geopolitics of energy from Pakistan's viewpoint.     

Synthesis of yttrium and cerium doped ZnO nanoparticles as highly inexpensive and stable photocatalysts for hydrogen evolution

Yttrium and cerium co-doped ZnO nanoparticles were synthesized by combustion route and characterized using X-ray diffraction(XRD),scanning electron microscopy(SEM),Brunauer-Emmett-Teller(BET),energy dispersive spectroscopy(EDS),X-ray photoelectron spectroscopy(XPS),UV-visible diffuse reflectance spectroscopy(UV-vis DRS),photoluminescence(PL)and electrochemical impedance spectroscopy(EIS)techniques.The introduction of yttrium ions has efficiently increased the relative percentage of Ce³⁺ions in ZnO.Yttrium and cerium co-doped ZnO shows efficient photo activity for hydrogen evolution(10.61 mmol/((g·h))higher than previously reported optimal value for rare earth codoped ZnO photocatalysts.This remarkably increased hydrogen evolution can be ascribed to the synergy between electronic anchoring effect of Y³⁺/Y²⁺and Ce⁴⁺/Ce³⁺redox couples.This report presents new idea for the synthesis of efficient photocatalyst using economical route and ion anchoring effect.The hydrogen evolution was also tested using Na₂S and Na₂SO₃as electron donors under visible light illumination.The synthesized photocatalysts also exhibit high stability.     

Are specific emotions narrated differently?

Two studies test the assertion that anger, sadness, fear, pride, and happiness are typically narrated in different ways. Everyday events eliciting these 5 emotions were narrated by young women (Study 1) and 5- and 8-year-old girls (Study 2). Negative narratives were expected to engender more effort to process the event, be longer, more grammatically complex, more often have a complication section, and use more specific emotion labels than global evaluations. Narratives of Hogan’s (2003) juncture emotions anger and fear were expected to focus more on action and to contain more core narrative sections of orientation, complication, and resolution than narratives of the outcome emotions sadness and happiness. Hypotheses were confirmed for adults except for syntactic complexity, whereas children showed only some of these differences. Hogan’s theory that juncture emotions are restricted to the complication section was not confirmed. Finally, in adults, indirect speech was more frequent in anger narratives and internal monologue in fear narratives. It is concluded that different emotions should be studied in how they are narrated, and that narratives should be analyzed according to qualitatively different emotions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)