Performance of PAM/PEI gel system for water shut‐off in high temperature reservoirs: Laboratory study

A polymer gel is one of the common remediate methods to either reduce or totally block excessive water production in oilfields. Some systems demonstrated an excellent performance in treating the problem like polyacrylamide tert‐butyl acrylate (PAtBA)/polyethylenimine (PEI). In this study, polyacrylamide (PAM) was introduced as a cheap alternative to PAtBA that can tolerate high salinity reservoirs. The thermal stability of the PAM/PEI polymeric gel in saline water was examined at 150°C (302F). Samples prepared in sea water showed better stability compared with distilled and field water. Dynamic rheology and core‐flooding experiments were used to evaluate the PAM / PEI gel system at high temperatures. NaCl and NH₄Cl were evaluated as a possible retarders for delaying the gelation time in order to achieve a successful placement. NH₄Cl was found to be more effective retarder. Core‐flooding tests were conducted in sandstone and carbonate cores. The subject polymer gel was injected at rates typical of those in field applications. The injectivity of PAM/PEI was tested in Berea sandstone cores with initial permeability of ～45 mD. The post‐treatment of the system showed a permeability reduction of ～94% for a period of two weeks. The injectivity in low permeability carbonate cores required more retardation compared with the injectivity in sandstone cores. The gel reduced the permeability to brine in Indiana limestone core by 99.8% for more than 5 months. Rheology of cured gel samples indicated that the gel strength needs about one day of curing in the core for the strength to stabilize. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41869.     

The lower and upper approximations in a quotient hypermodule with respect to fuzzy sets

This paper provides a continuation of ideas presented by Davvaz and Mahdavipour [B. Davvaz, M. Mahdavipour, Roughness in modules, Inform. Sci. 176 (2006) 3658-3674]. The notion of hypermodule is a generalization of the notion of module. In this paper, we consider the quotient hypermodule M/A and interpret the lower and upper approximations as subsets of the quotient hypermodule M/A. Then, we introduce the concept of quotient rough sub-hypermodule. Also, using the concept of fuzzy sets, we introduce and discuss the concept of fuzzy rough hypermodules and then we obtain the relation between fuzzy rough sub-hypermodules and level rough sets. This relation is characterized as a necessary and sufficient condition.     

Use of multisensor and multitemporal geospatial datasets to extract the foundation characteristics of a large building: a case study

Bulletin of Engineering Geology and the Environment - The assessment of the ground conditions for large buildings is important because the results are sensitive to the ground conditions, especially...     

Maleated high oleic sunflower oil‐treated cellulose fiber‐based styrene butadiene rubber composites

Surface treatment of cellulose fibers was performed with maleated high oleic sunflower oil (MSOHO). The MSOHO‐treated cellulose fibers and unmodified cellulose fibers were dispersed in styrene butadiene rubber (SBR) using a two roll mill. Vapor grown carbon nanofibers (VGCNF) were also incorporated at only one parts per hundred rubber (phr) in unmodified cellulose fibers/SBR composites. The curing characteristics, mechanical properties, and water absorption of the resulting composites were determined. MSOHO‐treated fibers completed curing at much slower rate and also decreased the cure density of composites, compared to unmodified fibers. In contrast, the combination of VGCNF and unmodified cellulose fibers accelerated the SBR curing process, but reduced the cure density. MSOHO treatment improved the dispersion of the fibers in the SBR, which resulted in improved mechanical properties of composites. The composite incorporating 1 phr VGCNF and 15 phr unmodified cellulose fibers showed the greatest increase in tensile strength as compared with neat SBR. POLYM. COMPOS. 37:1113–1121, 2016. © 2014 Society of Plastics Engineers     

Thermodynamic parameters of activation for photodegradation of phenolics

The photocatalytic degradation of three phenolics namely phenol, 4-chlorophenol and 4-nitrophenol were carried out in aerated aqueous suspension of TiO₂ irradiated by ultraviolet light. The influence of temperature at optimized pH and TiO₂ concentration was studied. The degradation kinetics were somewhat accelerated by increase in temperature in the range 25–45 °C and apparent activation energy was calculated to be 9.68–21.44 kJ mol^?1. Thermodynamic parameters of activation were also assessed for the degradation process. Formation of acidic species results in decrease in pH of solution. The appearance and the evolution of main intermediate species like hydroquinone, benzoquinone and catechol during the degradation process were computed by UV–vis spectral analysis.     

传统发酵霉豆渣中微生物的分离及其作为豆渣发酵剂的应用

豆渣是大豆加工的副产品,具有产量大但应用不足的特点。为提高豆渣的利用率,开发新型豆渣产品。该实验对湖南邵阳霉豆渣进行微生物分离,旨在得到能利用豆渣营养物质的菌株。共分离33株菌,分别为乳酸菌13株,戊糖乳杆菌（Lactobacillus pentosus）、乳酸片球菌（Pediococcus lolii）、短乳酸杆菌（Lactobacillus brevis）、发酵乳杆菌（Lactobacillus fermentum）、融合魏斯氏（Weissella confusa）;芽孢杆菌7株,枯草芽孢杆菌（Bacillus subtilis）、贝莱斯芽孢杆菌（Bacillus velezensis）;葡萄球菌9株,松鼠葡萄球菌（Staphylococcus sciuri）、克氏葡萄球菌（Staphylococcus kloosii）、鸡葡萄球菌（Staphylococcus gallinarum）、缓慢葡萄球菌（Staphylococcus lentus）;2株酵母菌,库德毕赤酵母（Pichia kudriavzevii）、白地霉（Geotrichum candidum）;2株霉菌,总状横梗霉（Lichtheimia ramosa）和伞房横梗霉（Lichtheimia corymbifera）。用白地霉、总状横梗霉和伞房横梗霉固态发酵豆渣,结果表明,发酵豆渣总酚和抗氧化活性明显高于未发酵的豆渣（p<0.05）,发酵6 d,ABTS清除率和总酚含量达到最高,为92.67%和134.35 mg GAE/10 g,DPPH清除率为79.98%。证实发酵豆渣可提高豆渣营养价值,有助于豆渣在食品及其副产品的应用。     

Sooting tendencies of primary reference fuels in atmospheric laminar diffusion flames burning into vitiated air

In this study, the sooting tendencies of primary reference fuels (PRFs) are measured in term of yield sooting indices (YSIs) in methane diffusion flames doped with the vapors of PRFs. The present paper represents an incremental advance complementing the original methodology prescribed by McEnally and Pfefferle. The influence of both PRF formulation and CO₂ dilution of the coflowing air on the YSIs is also assessed. The diffusion flames burning in a coflowing oxidizer stream are established over the Santoro’s burner and vapor of the liquid fuel to be investigated is injected into the fuel stream. Laser extinction measurements are performed to map the two-dimensional field of soot volume fraction in the flame. For the pure liquid hydrocarbons investigated, i.e., n-hexane, n-heptane, isooctane, and benzene, the YSI reported in the original paper by McEnally and Pfefferle quantitatively predict the sooting propensities, measured here at much higher dopant concentrations. The present study therefore extends the consistency of the YSI methodology on the Santoro’s burner. For blends of n-heptane and isooctane, the sooting tendency of doped flames exhibits regular and monotonic trends and decreases with increasing n-heptane mole fraction or CO₂ dilution. Interestingly, the evolution of YSI with the isooctane mole fraction exhibits a strong similarity for varying CO₂ mole fraction. A quadratic least-squares fit is then derived, providing a phenomenological model of YSI as a function of both isooctane mole fraction in the fuel stream and CO₂ mole fraction in the oxidizer. A non-negligible cross effect of PRF formulation and CO₂ dilution on YSI is revealed. The method elaborated within the framework of the present paper could be extended to surrogate fuels. This would help develop a comprehensive database and empirical correlations that could predict the sooting propensities of different surrogate fuels, therefore their potentially mitigationed soot production through control of fuel composition and/or exhaust gas recirculation. This database would also be useful for the validation of CFD simulations incorporating sophisticated model of soot production.     

Proportional damping approximation using the energy gain and simultaneous perturbation stochastic approximation

The design of vector second-order linear systems for accurate proportional damping approximation is addressed. For this purpose an error system is defined using the difference between the generalized coordinates of the non-proportionally damped system and its proportionally damped approximation in modal space. The accuracy of the approximation is characterized using the energy gain of the error system and the design problem is formulated as selecting parameters of the non-proportionally damped system to ensure that this gain is sufficiently small. An efficient algorithm that combines linear matrix inequalities and simultaneous perturbation stochastic approximation is developed to solve the problem and examples of its application to tensegrity structures design are presented.