895 resultados para IN-OIL MICROEMULSIONS


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Purpose - The purpose of the paper is to the identify risk factors, which affect oil and gas construction projects in Vietnam and derive risk responses. Design/methodology/approach - Questionnaire survey was conducted with the involvement of project executives of PetroVietnam and statistical analysis was carried out in order to identify the major project risks. Subsequently, mitigating measures were derived using informal interviews with the various levels of management of PetroVietnam. Findings - Bureaucratic government system and long project approval procedures, poor design, incompetence of project team, inadequate tendering practices, and late internal approval processes from the owner were identified as major risks. The executives suggested various strategies to mitigate the identified risks. Reforming the government system, effective partnership with foreign collaborators, training project executives, implementing contractor evaluation using multiple criteria decision-making technique, and enhancing authorities of project people were suggested as viable approaches. Practical implications - The improvement measures as derived in this study would improve chances of project success in the oil and gas industry in Vietnam. Originality/value - There are several risk management studies on managing projects in developing countries. However, as risk factors vary considerably across industry and countries, the study of risk management for successful projects in the oil and gas industry in Vietnam is unique and has tremendous importance for effective project management.

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Operating oil pipelines in an optimum capacity through out its life, effective construction management and failure free operations are considered as critical success factors in oil transportation business. Operating oil pipelines in derated capacity due to deteriorating pipeline health or lack of demand, non-ability of augmenting pipeline capacity despite of demand, non-achievement of time, cost, and quality of pipeline construction projects, and many failures of pipelines despite of huge expenditure in inspection and maintenance are the common phenomena in oil pipelines industry. These not only cause business loss, but also increase stakeholders' concerns for sustainable development. This study addresses the above issues using an analytical framework through stakeholders' involvement. Copyright © 2006 Inderscience Enterprises Ltd.

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The organic matter in five oil shales (three from the Kimmeridge Clay sequence, one from the Oxford Clay sequence and one from the Julia Creek deposits in Australia) has been isolated by acid demineralisation, separated into kerogens and bitumens by solvent extraction and then characterised in some detail by chromatographic, spectroscopic and degradative techniques. Kerogens cannot be characterised as easily as bitumens because of their insolubility, and hence before any detailed molecular information can be obtained from them they must be degraded into lower molecular weight, more soluble components. Unfortunately, the determination of kerogen structures has all too often involved degradations that were far too harsh and which lead to destruction of much of the structural information. For this reason a number of milder more selective degradative procedures have been tested and used to probe the structure of kerogens. These are: 1. Lithium aluminium hydride reduction. - This procedure is commonly used to remove pyrite from kerogens and it may also increase their solubility by reduction of labile functional groups. Although reduction of the kerogens was confirmed, increases in solubility were correlated with pyrite content and not kerogen reduction. 2. O-methylation in the presence of a phase transfer catalyst. - By the removal of hydrogen bond interactions via O-methylation, it was possible to determine the contribution of such secondary interactions to the insolubility of the kerogens. Problems were encountered with the use of the phase transfer catalyst. 3. Stepwise alkaline potassium permanganate oxidation. - Significant kerogen dissolution was achieved using this procedure but uncontrolled oxidation of initial oxidation products proved to be a problem. A comparison with the peroxytrifluoroaceticacid oxidation of these kerogens was made. 4. Peroxytrifluoroacetic acid oxidation. - This was used because it preferentially degrades aromatic rings whilst leaving any benzylic positions intact. Considerable conversion of the kerogens into soluble products was achieved with this procedure. At all stages of degradation the products were fully characterised where possible using a variety of techniques including elemental analysis, solution state 1H and 13C nuclear magnetic resonance, solid state 13C nuclear magnetic resonance, gel-permeationchromatography, gas chromatography-mass spectroscopy, fourier transform infra-red spectroscopy and some ultra violet-visible spectroscopy.

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Some of the problems arising from the inherent instability of emulsions are discussed. Aspects of emulsion stability are described and particular attention is given to the influence of the chemical nature of the dispersed phase on adsorbed film structure and stability, Emulsion stability has been measured by a photomicrographic technique. Electrophoresis, interfacial tension and droplet rest-time data were also obtained. Emulsions were prepared using a range of oils, including aliphatic and aromatic hydrocarbons, dispersed In a solution of sodium dodecyl sulphate. In some cases a small amount of alkane or alkanol was incorporated into the oil phase. In general the findings agree with the classical view that the stability of oil-in-water emulsions is favoured by a closely packed interfacial film and appreciable electric charge on the droplets. The inclusion of non-ionic alcohol leads to enhanced stability, presumably owing to the formation of a "mixed" interfacial film which is more closely packed and probably more coherent than that of the anionic surfactant alone. In some instances differences in stability cannot he accounted for simply by differences in interfacial adsorption or droplet charge. Alternative explanations are discussed and it is postulated that the coarsening of emulsions may occur not only hy coalescence but also through the migration of oil from small droplets to larger ones by molecular diffusion. The viability of using the coalescence rates of droplets at a plane interface as a guide to emulsion stability has been researched. The construction of a suitable apparatus and the development of a standard testing procedure are described. Coalescence-time distributions may be correlated by equations similar to those presented by other workers, or by an analysis based upon the log-normal function. Stability parameters for a range of oils are discussed in terms of differences in film drainage and the natl1re of the interfacial film. Despite some broad correlations there is generally poor agreement between droplet and emulsion stabilities. It is concluded that hydrodynamic factors largely determine droplet stability in the systems studied. Consequently droplet rest-time measurements do not provide a sensible indication of emulsion stability,

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This survey is devoted to some fractional extensions of the incomplete lumped formulation, the lumped formulation and the formulation of Lauwerier of the temperature field problem in oil strata. The method of integral transforms is used to solve the corresponding boundary value problems for the fractional heat equation. By using Caputo’s differintegration operator and the Laplace transform, new integral forms of the solutions are obtained. In each of the different cases the integrands are expressed in terms of a convolution of two special functions of Wright’s type.

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General note: Title and date provided by Bettye Lane.

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By proposing a numerical based method on PCA-ANFIS(Adaptive Neuro-Fuzzy Inference System), this paper is focusing on solving the problem of uncertain cycle of water injection in the oilfield. As the dimension of original data is reduced by PCA, ANFIS can be applied for training and testing the new data proposed by this paper. The correctness of PCA-ANFIS models are verified by the injection statistics data collected from 116 wells inside an oilfield, the average absolute error of testing is 1.80 months. With comparison by non-PCA based models which average error is 4.33 months largely ahead of PCA-ANFIS based models, it shows that the testing accuracy has been greatly enhanced by our approach. With the conclusion of the above testing, the PCA-ANFIS method is robust in predicting the effectiveness cycle of water injection which helps oilfield developers to design the water injection scheme.

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Purpose: To formulate the water in oil (W/O) emulsion of corn silk (CS) extract and to evaluate its stability at various storage conditions. Methods: Ethanol CS extract was prepared using maceration (cold) technique. A 4 % CS emulsion was prepared using varying concentrations of liquid paraffin, ABIL EM90 and water. The formulations were kept at 40 oC for 28 days and to screen out the less stable formulations. The remaining formulations were further stressed at 50 oC to choose the most stable formulation. The optimized formulation was evaluated for physical characteristics including phase separation, rheology and mean droplet size. The physical stability of the formulation was evaluated by monitoring these parameters over a period of 12 weeks at 8, 25, 40 and 40 oC, and 75 % RH. Results: The chosen formulation showed good resistance to phase separation on centrifugation under all storage conditions. Rheological behavior followed non-Newtonian pseudoplastic pattern at various storage conditions. Mean droplet size of freshly prepared formulation was 2.98 ± 1.32 µm and did not show significant (p < 0.05) changes at normal storage conditions (8 and 25 oC). Conclusion: The findings indicate that the developed CS extract W/O emulsion is stable and therefore may be suitable for topical use on skin as an antioxidant preparation.

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The aim of this study was to investigate the effects of the emulsifying conditions and emulsifier type on production of water-in-oil (W/O) emulsions encapsulating ascorbic acid derivatives by microchannel (MC) emulsification. The ascorbic acid derivatives added in a dispersed aqueous phase are calcium ascorbate (AA-Ca) and ascorbic acid 2-glucoside (AA-2G). The continuous phase used was decane, soybean oil or their mixture, containing 5% (w/w) tetraglycerin monolaurate condensed ricinoleic acid ester or sorbitan trioleate. A hydrophobized silicon MC array plate (model: MS407) with a channel depth of 7μm was used for MC emulsification. The use of MC emulsification enabled successful encapsulation of AA-Ca and AA-2G in monodisperse W/O emulsion droplets with coefficients of variation (CV) less than 7%. Their average droplet diameter (dav) increased with increasing the continuous-phase viscosity that is similar or higher than the dispersed-phase viscosity. The dav and CV of the resultant monodisperse W/O emulsions were unaffected by the dispersed-phase flow rate below critical values of 1.2-1.6mLh-1 when using decane as the continuous-phase medium.

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This study sought to encapsulate a high concentration of L-ascorbic acid, up to 30% (w/v), in the inner aqueous phase of water-in-oil-water (W/O/W) emulsions with soybean oil as the oil phase. Two-step homogenization was conducted to prepare W/O/W emulsions stabilized by a hydrophobic emulsifier and 30% (v/v) of W/O droplets stabilized by a hydrophilic emulsifier. First-step homogenization prepared W/O emulsions with an average aqueous droplet diameter of 2.0 to 3.0 μm. Second-step homogenization prepared W/O/W emulsions with an average W/O droplet diameter of 14 to 18 μm and coefficients of variation (CVs) of 18% to 25%. The results indicated that stable W/O/W emulsions containing a high concentration of L-ascorbic acid were obtained by adding gelatin and magnesium sulfate in the inner aqueous phase and glucose in both aqueous phases. L-Ascorbic acid retention in the W/O/W emulsions was 40% on day 30 and followed first-order kinetics.

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The present study was conducted to encapsulate higher concentration of l-ascorbic acid up to (30 g 100 mL-1) in the dispersed phase of water-in-oil (W/O) emulsions. Their continuous phase contained refined soybean oil or Moringa oleifera oil and a food-grade hydrophobic emulsifier. The volume fraction of the dispersed phase was fixed as to 30%. W/O emulsions with l-ascorbic acid retention greater than 95% were prepared using rotor-stator homogenizer at 7000 rpm for 5 min. The prepared W/O emulsions under this operating conditions had average droplet diameter of 2.0-3.0 μm and coefficients of variation of 13%-22%. All the W/O emulsions were stable for more than 30 days at 4 °C or 25 °C with slight increase in average droplet diameter and without phase separation. Their l-ascorbic acid retentions were 50 g 100 g-1 at 4 °C and 30 g 100 g-1 at 25 °C after 30 days of storage. l-ascorbic acid retention ratio of the prepared W/O emulsions followed first-order kinetics with a good fit.

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This thesis examines the relationship between oil prices and economic activity, and it attempts to address the question: do increases in oil prices (oil shocks) precede U.S. recessions? This paper also applied macroeconomics, either through the direct use of a macroeconomic point of view or using a combination of mathematical and statistical models. Two mathematical and statistical models are used to determine the ability of oil prices to predict recessions in the United States. First, using the binary cyclical (Bry-Boschan method) indicator procedure to test the turning point of oil prices compared with turning points in GDP finds that oil prices almost always turn five month before a recession, suggesting that an oil shock might occur before a recession. Second, the Granger causality test shows that oil prices change do Granger cause U.S. recessions, indicating that oil prices are a useful signal to indicate a U.S. recession. Finally, combining this analysis with the literature, there are several potential explanations that the spike in oil prices result in slower GDP growth and are a contributing factor to U.S. recessions.

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This research focuses on polymer stabilized high internal phase emulsions for oil spill recovery and oil safety.

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CeF3 and lutetium-doped CeF3 nanoparticles with the dopant concentration of 17, 25, 30, 42 and 50 mol% (molar ratio, Lu/Ce) were synthesized. XRD patterns were indexed to a pure CeF3 hexagonal phase even under the dopant concentration of 50 mol%. Environmental scanning electron microscopy-field emission gun (ESEM-FEG) was used to characterize the morphology of the final products. From the luminescence spectra of the products, we can get a broad emission ranging from 290 to 400 nm with peak at 325 nm. Lutetium-doping increases the luminescence intensity. We got. the most intense luminescence at the dopant concentration of 30 mol%.