A study on siro,solo, compact,and conventional ring-spun yarns. Part III: modeling fiber migration using modular adaptive neuro-fuzzy inference system

The importance of fiber migration in spun yarns as a means of securing cohesion and strength has been emphasized in the literature. However, analyzing migration behavior of fibers is a time-consuming and tedious task. A three-stage hybrid model was developed to estimate yarn migratory properties based on some physical and mechanical properties of spun yarns. Achieving the objectives of this research, general physical, mechanical, and structural properties of spun yarns together with existing standards were thoroughly studied. At the first stage, using stepwise regression analysis, key variables were selected. At the second stage, data-set was clustered into subpopulations by means of K-means in order to decrease effects of noise, rebate complexity of the patterns, and develop a modular model. At the third stage, using adaptive neuro-fuzzy inference system, the target value was predicted. Finally, evaluation of the proposed model was carried out by applying it on the test set.     

An efficient heuristic versus a robust hybrid meta-heuristic for general framework of serial–parallel redundancy problem

We present a heuristic approach to solve a general framework of serial–parallel redundancy problem where the reliability of the system is maximized subject to some general linear constraints. The complexity of the redundancy problem is generally considered to be NP-Hard and the optimal solution is not normally available. Therefore, to evaluate the performance of the proposed method, a hybrid genetic algorithm is also implemented whose parameters are calibrated via Taguchi's robust design method. Then, various test problems are solved and the computational results indicate that the proposed heuristic approach could provide us some promising reliabilities, which are fairly close to optimal solutions in a reasonable amount of time.     

Measurement and prediction of the rate of deposition of flocculated asphaltene particles from oil

Asphaltene deposition is one of the unresolved problems in oil industries. Little information is available on the critical question of “how fast” the flocculated asphaltene particles deposit across the production wells from the flowing oil. In this study, the mechanisms of deposition of flocculated asphaltene particles from oil have been studied experimentally and theoretically under forced convective conditions using an accurate thermal approach. The effects of oil velocity, flocculated asphaltene concentration and temperature on the rate of asphaltene deposition are investigated. It is observed that during the first few weeks the deposition mechanism is dominant and the erosion of the deposit is almost negligible. The rate of asphaltene deposition increases with increasing flocculated asphaltene concentration and temperature while it decreases with increasing oil velocity. After clarification of the effects of operating parameters on the deposition process, the results of the experiments are used to develop a mechanistic model for the prediction of the rate of asphaltene deposit formation under forced convective conditions. The predictions of the suggested model for the deposition rate of asphaltene are compared with measured data. Quantitative and qualitative agreement between measured and predicted asphaltene deposition rates is good.     

A laboratory study of hot WAG injection into fractured and conventional sand packs

Gas injection is the second largest enhanced oil recovery process,next only to the thermal method used in heavy oil fields.To increase the extent of the reservoir contacted by the injected gas,the gas is generally injected intermittently with water.This mode of injection is called water-alternating-gas(WAG).This study deals with a new immiscible water alternating gas(IWAG) EOR technique,"hot IWAG" which includes combination of thermal,solvent and sweep techniques.In the proposed method CO2 will be superheated above the reservoir temperature and instead of normal temperature water,hot water will be used.Hot CO2 and hot water will be alternatively injected into the sand packs.A laboratory test was conducted on the fractured and conventional sand packs.Slugs of water and CO2 with a low and constant rate were injected into the sand packs alternatively;slug size was 0.05 PV.Recovery from each sand pack was monitored and after that hot water and hot CO2 were injected alternatively under the same conditions and increased oil recovery from each sand pack and breakthrough were measured.Experimental results showed that the injection of hot WAG could significantly recover residual oil after WAG injection in conventional and fractured sand packs.     

Evaluation of the Effects of Cucumis sativus Seed Extract on Serum Lipids in Adult Hyperlipidemic Patients: A Randomized Double‐Blind Placebo‐Controlled Clinical Trial

Hyperlipidemia is associated with increased risk of atherosclerosis; therefore, control of this risk factor is very important in preventing atherosclerosis. Cucumber (Cucumis sativus) seed is used traditionally as a lipid‐lowering nutritional supplement. The aim of this study was to evaluate the effect of cucumber seed extract on serum lipid profile in adult patients with mild hyperlipidemia. In a randomized double‐blind placebo‐controlled clinical trial, hyperlipidemic patients with inclusion criteria were randomly and equally assigned to either Cucumis or placebo groups and used one medicinal or placebo capsule, respectively, once daily with food for 6 wk. Body mass index (BMI) as well as fasting serum levels of total cholesterol, triglycerides (TG), low‐density lipoprotein (LDL‐C), and high‐density lipoprotein (HDL‐C) were measured for all patients pre‐ and post‐intervention and finally the changes were compared between the groups. Twenty‐four patients in Cucumis group and 23 patients in placebo group completed the study. Cucumis seed extract resulted in significant reduction of total cholesterol (P = 0.016), LDL‐C (P < 0.001), TG (P < 0.001), and BMI (P < 0.001) as well as significant increase of HDL‐C (P = 0.012) compared to placebo. In conclusion, the consumption of C. sativus seed extract with daily dose of 500 mg results in desirable effects on serum lipid profile in adult hyperlipidemic patients. Therefore, cucumber seed could be considered as a food supplement for treatment of dyslipidemia.     

Influence of mould design on the solidification of heavy forging ingots of low alloy steels by numerical simulation

Ingot casting of a 6-ton, heat-treatable Cr–Mo low alloy steel was simulated using finite element method in three dimensions. Effects of casting parameters including bottom pouring rate, mould slenderness ratio, mould slope, and height and shape of the hot top isolate on solidification behaviour and crack susceptibility during subsequent hot forging of the ingot were investigated. The simulation model was validated against experimental data of two different ingot mould designs. Influences of the casting parameters on the riser efficiency and possible crack formation in the intersection of hot top and ingot body during subsequent open-die forging of the cast steel ingots were discussed. Results showed that pouring the melt under a constant rate, reducing the mould slenderness ratio, and using a proper design for the hot top isolate would all improve the riser efficiency and thereby possibly reduce crack susceptibility during subsequent hot forging.     

Heat Treatment of Closed-Cell A356 + 4 wt.%Cu + 2 wt.%Ca Foam and Its Effect on the Foam Mechanical Behavior

In this investigation, aluminum-silicon alloy foam is developed by adding certain amounts of copper and calcium elements in A356 alloy. Addition of 4 wt.%Cu + 2 wt.%Ca to the melt changed bubbles morphology from ellipsoid to spherical by decreasing Reynolds number and increasing Bond number. Compression behavior and energy absorption of the foams are assessed before and after aging. Solid solution treatment and aging lead to the best mechanical properties with 170% enhancement in yield strength and 185% improvement in energy absorption capacity as compared to non-heat-treated foams. The metallographic observations showed that bubbles geometry and structure in the A356 + 4wt.% Cu + 2 wt.%Ca foam are more homogeneous than the A356 foam.     

Fatty acid and hydroxy acid adaptation in three gram-negative hydrocarbon-degrading bacteria in relation to carbon source

The lipids of three gram-negative bacteria, Acineto-bacter calcoaceticus, Marinobacter aquaeolei, and Pseudomonas oleovorans grown on mineral media supplemented with ammonium acetate or hydrocarbons, were isolated, purified, and their structures determined. Three pools of lipids were isolated according to a sequential procedure: unbound lipids extracted with organic solvents, comprising metabolic lipids and the main part of membrane lipids, OH⁻-labile lipids (mainly ester-bound in the lipopolysaccharides, LPS) and H⁺-labile lipids (mainly amidebound in the LPS). Unsaturated FA composition gave evidence for an aerobic desaturation pathway for the synthesis of these acids in A. calcoaceticus and M. aquaeolei, a nonclassic route in gram-negative bacteria. Surprisingly, both aerobic and anaerobic pathways are operating in the studied strain of P. oleovorans. The increase of the proportion of saturated FA observed for the strain of P. oleovorans grown on light hydrocarbons would increase the temperature transition of the lipids for maintaining the inner membrane fluidity. An opposite phenomenon occurs in A. calcoaceticus and M. aquaeolei grown on solid or highly viscous C₁₉ hydrocarbons. The increases of FA<C₁₈ when the bacteria were grown on n-nonadecane, or of iso-FA in cultures on iso-nonadecane would decrease the transition temperature of the lipids, to maintain the fluidity of the inner membranes. Moreover, P. oleovorans grown on hydrocarbons greatly decreases the proportion of β-hydroxy acids of LPS, thus likely maintaining the physical properties of the outer membrane. By contrast, no dramatic change in hydroxy acid composition occurred in the other two bacteria.     

A novel porous nanocomposite of aminated silica MCM‐41 and nylon‐6: Isotherm,kinetic, and thermodynamic studies on adsorption of Cu(II) and Cd(II)

Porous amine‐modified MCM‐41/Nylon‐6 nanocomposite (NH₂‐MCM‐41/NY6 NC) was synthesized by a facile solution casting protocol, which was used as an effective adsorbent for the removal of Cu(II) and Cd(II) from aqueous media. The physicochemical properties of NH₂‐MCM‐41/NY6 NC were studied by scanning and transmission electron microscopies, thermogravimetric analysis, etc. The influence of pH, adsorbent dose, contact time and initial concentration on adsorption performance were investigated in detail. Kinetic and isotherm parameters were evaluated and the data fitted well to the pseudo‐second order and Freundlich isotherm model, respectively. The maximum adsorption capacities of Cu(II) and Cd(II) were about 35.84 and 27.5 mg·g^?1, respectively. The K_d of NH₂‐MCM‐41/NY6 NC for Cu(II) (> ) and Cd(II) (> ) ions uptake in aqueous solution, showed very good values. Thermodynamic parameters suggest that the adsorption is a spontaneous process with an endothermic nature. According to the results obtained, we conclude that this novel porous NH₂‐MCM‐41/NY6 NC could be used for the removal of heavy metal ions from an aqueous solution. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45383.