Um die anderen Arten von Veröffentlichungen zu diesem Thema anzuzeigen, folgen Sie diesem Link: The effect of oil on differential characteristics.
Zeitschriftenartikel zum Thema „The effect of oil on differential characteristics“
Geben Sie eine Quelle nach APA, MLA, Chicago, Harvard und anderen Zitierweisen an
Machen Sie sich mit Top-50 Zeitschriftenartikel für die Forschung zum Thema "The effect of oil on differential characteristics" bekannt.
Neben jedem Werk im Literaturverzeichnis ist die Option "Zur Bibliographie hinzufügen" verfügbar. Nutzen Sie sie, wird Ihre bibliographische Angabe des gewählten Werkes nach der nötigen Zitierweise (APA, MLA, Harvard, Chicago, Vancouver usw.) automatisch gestaltet.
Sie können auch den vollen Text der wissenschaftlichen Publikation im PDF-Format herunterladen und eine Online-Annotation der Arbeit lesen, wenn die relevanten Parameter in den Metadaten verfügbar sind.
Sehen Sie die Zeitschriftenartikel für verschiedene Spezialgebieten durch und erstellen Sie Ihre Bibliographie auf korrekte Weise.
1
Shaikhiev, Ildar G., Irina N. Shumkova, Svetlana V. Sverguzova und Zhanna A. Sapronova. „Effect of firing temperature waste from water treatment on sorption characteristics of petroleum products“. RUDN Journal of Ecology and Life Safety 27, Nr. 4 (15.12.2019): 264–74. http://dx.doi.org/10.22363/2313-2310-2019-27-4-264-274.
Der volle Inhalt der QuelleAnnotation:
The article reflects the results of research on the influence of roast temperature of water treatment waste obtained from drinking water generation (at the water treatment plant in Nizhnekamsk, Republic of Tatarstan) for sorption characteristics for native and used oil products - oils 5W40, 15W40 and И-20А. The methods of instrumental and computational means of research are presented. Differential thermal analysis and differential scanning calorimetry of water treatment waste were performed. The graphs of the influence of roast temperature on the aqueous extract pH value, maximum oil capacity and water absorption were constructed. It was found that at high temperatures, the decomposition of organic compounds with formation of carbon black occurs. It increases the maximum oil capacity in dynamic and static conditions in water and water absorption. It is determined that the best adsorption indicators are achieved for a sample of water treatment waste subjected to heat treatment at 600 C.
2
Zullo, Biagi Angelo, und Gino Ciafardini. „Differential Microbial Composition of Monovarietal and Blended Extra Virgin Olive Oils Determines Oil Quality during Storage“. Microorganisms 8, Nr. 3 (13.03.2020): 402. http://dx.doi.org/10.3390/microorganisms8030402.
Der volle Inhalt der QuelleAnnotation:
Extra virgin olive oil (EVOO) contains a biotic fraction, which is characterized by various microorganisms, including yeasts. The colonization of microorganisms in the freshly produced EVOO is determined by the physicochemical characteristics of the product. The production of blended EVOO with balanced taste, which is obtained by blending several monovarietal EVOOs, modifies the original microbiota of each oil due to the differential physico-chemical characteristics of the blended oil. This study aimed to evaluate the effect of microbial composition on the stability of the quality indices of the monovarietal and blended EVOOs derived from Leccino, Peranzana, Coratina, and Ravece olive varieties after six months of storage. The yeasts survived only in the monovarietal EVOOs during six months of storage. Barnettozyma californica, Candida adriatica, Candida diddensiae, and Yamadazyma terventina were the predominant yeast species, whose abundance varied in the four monovarietal EVOOs. However, the number of yeasts markedly decreased during the first three months of storage in all blended EVOOs. Thus, all blended EVOOs were more stable than the monovarietal EVOOs as the abundance and activity of microorganisms were limited during storage.
3
Ferguson, Helen A., S. A. (Raj) Mehta, R. Gordon Moore, Nancy E. Okazawa und Matthew G. Ursenbach. „Oxidation Characteristics of Light Hydrocarbons for Underbalanced Drilling Applications“. Journal of Energy Resources Technology 125, Nr. 3 (29.08.2003): 177–82. http://dx.doi.org/10.1115/1.1586935.
Der volle Inhalt der QuelleAnnotation:
This investigation is directly relevant to various applications associated with the safety aspects of underbalanced drilling operations where de-oxygenated air may be co-injected with oil-based drilling fluid. However, de-oxygenated air often still contains up to 5% oxygen by volume. This residual oxygen can react with oil during the drilling process, thereby forming potentially hazardous oxidized hydrocarbons and compromising the safety of drilling operations. This article examines the conditions and processes by which oxidation reactions occur and may be helpful in reducing risk in drilling operations. This project characterizes the oxidation behavior of several oils and a typical oil-based drilling fluid at atmospheric and elevated pressures using thermogravimetry (TG) and pressurized differential scanning calorimetry (PDSC). Tests performed on mineral matrix (core) from the oil reservoirs showed no reactivity in both inert and oxidizing atmospheres. In an inert atmosphere, tests on all hydrocarbon samples showed only vaporization, no reactivity. In an oxidizing environment, the tests on hydrocarbons showed several oxidation regions. The presence of core had no effect on the behavior of the hydrocarbons tested in an inert atmosphere but accelerated the higher temperature oxidation reactions of the oil samples. The oil-based drilling fluid exhibited the opposite effect—the presence of core material retarded the oxidation reactions. This is perhaps due to the presence of an oxygen scavenger reacting with oxygen-containing clays present in the mineral matrix. In all tests performed on mixtures of hydrocarbon and core in oxidizing atmospheres, elevated pressures resulted in acceleration of the lower and higher temperature reaction regions.
4
Chu, Xin Xing, und Feng Lan Wang. „Analysis of Vibration Characteristics of a Cracked Rotor“. Applied Mechanics and Materials 620 (August 2014): 296–99. http://dx.doi.org/10.4028/www.scientific.net/amm.620.296.
Der volle Inhalt der QuelleAnnotation:
This paper studies the Jeffcott cracked rotor based on level set, considering the oil film oscillation effects on crack rotor, building the stiffness matrix of the cracked rotor in the fixed coordinate system and the moving coordinate, deriving the nonlinear differential equations of coupled vibration of a cracked rotor, and analysis of its dynamic characteristic combined with case. Analysis shows that: crack rotor can produce nonlinear vibration in the crack and Oil film oscillation can be coupled bending and torsional vibration of cracked rotor. The analysis results provides practical basis for diagnosing Resonance of the rotor system fault and the safe operation of rotor.
5
Koochakzaei, Alireza, Hossein Ahmadi und Mohsen Mohammadi Achachlouei. „Performance Evaluation of Dimethyl Silicone Oil as Archaeological Dry Leather Lubricant“. Journal of the American Leather Chemists Association 115, Nr. 4 (01.04.2020): 140–44. http://dx.doi.org/10.34314/jalca.v115i4.3800.
Der volle Inhalt der QuelleAnnotation:
This study aimed to investigate?the treatment effect?of dimethyl silicone oil on archaeological dried leather. Leather samples, without treatment and treated in a vacuum, were submitted to an accelerated aging at 100°C for 72 hours. In order to evaluate the efficacy of treatment, leather characteristics were examined before and after treatment with dimethyl silicone oil and after accelerated aging. Colorimetry, ATR-FTIR spectroscopy, shrinkage temperature measurement and differential scanning calorimetry were used to examine the leather characteristics and the effectiveness and stability of treatment. The results revealed that the dimethyl silicone oil has a suitable performance in the treatment of dry leather. The results also showed that the use of dimethyl silicone oil significantly reduces the changes in leather during accelerated aging. In other words, dimethyl silicone oil treatment improves the leather stability against deterioration.
6
Chantola, Neelam, und S. B. Singh. „The effect of transformer parameters on reliability assessment with the help of health index“. International Journal of Quality & Reliability Management 36, Nr. 6 (03.06.2019): 895–916. http://dx.doi.org/10.1108/ijqrm-08-2018-0215.
Der volle Inhalt der QuelleAnnotation:
Purpose The purpose of this paper is to study various reliability measures like reliability, mean time to failure (MTTF) and sensitivity of transformer including different parameters of insulating oil/paper as health index. Design/methodology/approach The reliability characteristics of transformer incorporating different parameters of insulating oil as well as paper have been evaluated using Markov process incorporating Gumbel–Hougaard copula, Laplace transforms and supplementary variable technique. The parameters taken into consideration are breakdown voltage (BDV) and moisture content (MC) of both insulating oil and paper, and other parameters considered are interfacial tension (IFT), dissipation factor (DF), degree of polymerization (DOP) and furanic content (FC) for insulating oil and paper, respectively. By probability consideration and continuity influence, difference-differential equations have been obtained for the considered model. Findings Transition state probabilities, reliability, MTTF and sensitivity of the transformer corresponding to different parameters of insulating oil and paper have been evaluated with the help of aforementioned technique. Variations of reliability with respect to time along with the variations of MTTF and sensitivity have also been examined. Remarkable points during the study have also been pointed out. Originality/value Reliability characteristics of the transformer have been evaluated including two parameters: insulating oil and paper with the help of supplementary variable technique, considering two different types of repairs incorporating Gumbel–Hougaard family of copula unlike done earlier. Reliability, MTTF and sensitivity of transformer have been analyzed considering the parameters: BDV, MC, IFT and FC of insulating oil, and BDV, MC, DOP, DF of insulating paper.
7
Kortekaas, T. F. M. „Water/Oil Displacement Characteristics in Crossbedded Reservoir Zones“. Society of Petroleum Engineers Journal 25, Nr. 06 (01.12.1985): 917–26. http://dx.doi.org/10.2118/12112-pa.
Der volle Inhalt der QuelleAnnotation:
Kortekaas, T.F.M., SPE, Shell Research B.V. Abstract Festoon crossbedding is a typical sedimentary structure in sandstone reservoirs. It is especially common in fluvial deposits. The important elements are the foreset laminae, which vary in permeability, and the bottomsets of lower permeability. To understand the complex, direction-dependent displacement characteristics of a crossbedded reservoir zone, we first conducted numerical simulations on a centimeter scale in a small part of a water-wet crossbedded reservoir zone. The simulations indicate that, during water/oil displacement, considerable amounts of movable oil initially are left behind in the higher-permeability foreset laminae with fluid flow perpendicular to the foreset laminae, while with flow parallel to the foreset laminae the displacement efficiency is good. To describe the displacement characteristics on a reservoir scale, we developed a procedure for calculating direction-dependent pseudo relative-permeability and capillary-pressure curves to be used as input for the simulations of water/oil displacement in a crossbedded reservoir zone. On a reservoir scale, the displacement characteristics in a water-wet crossbedded reservoir zone are slightly more favorable with the main fluid flow perpendicular to the foreset laminae. perpendicular to the foreset laminae. In addition, the sensitivity of the displacement characteristics to moderate reductions in interfacial tensions (IFT's) and to increases in water viscosity was investigated, both on a centimeter scale and on a reservoir scale. The simulations indicate the potential for substantial improvement in recovery from crossbedded reservoir zones if diluted surfactant or polymer is added to the drive water. Introduction Detailed studies of the effect of reservoir heterogeneities on water/oil displacement characteristics have been conducted on a well-to-well (layering) scale and on a pore scale, but few studies on an intermediate scale have been done. Therefore, we embarked on a study of the effect of centimeter-scale heterogeneities on water/oil displacement characteristics. We studied festoon crossbedding, one of the typical sedimentary structures in sandstone reservoirs, particularly common in fluvial deposits. A schematic particularly common in fluvial deposits. A schematic representation of a small part of a crossbedded reservoir zone is given in Fig. 1A. The important elements are the foreset laminae, which vary in permeability, and the bottom-sets, which are of lower permeability. The width of the foreset laminae is exaggerated in Fig. 1A; typically it is a few centimeters. First, we will discuss a mathematical simulation study in a very limited area of a water-wet crossbedded reservoir zone (1.97 × 26.2 × 0.66 ft [0.6 × 8 × O.2 m]). After a brief discussion of the water/oil displacement characteristics near a single permeability transition, we present the water/oil displacement characteristics in some cross sections of a simplified model (Fig. 1B) of a small part of a crossbedded reservoir zone. In addition, their sensitivity to moderate reductions in IFT's and increases in water viscosity are discussed. Second, we describe the effect of crossbedding on water/oil displacement characteristics on a reservoir scale, discuss a procedure for calculating dynamic, direction-dependent pseudo relative-permeability and capillary-pressure curves, and present the results of a reservoir-scale mathematical simulation study, including the pseudo-properties. Also, the sensitivity of the results to changes pseudo-properties. Also, the sensitivity of the results to changes in IFT and water viscosity is discussed. One-Dimensional Water/Oil Displacement Characteristics Near an Abrupt Permeability Transition Permeability Transition suppose we have a one-dimensional (1D) system consisting of two zones with different absolute, but identical relative, permeabilities. Furthermore, the system is horizontal and contains oil and connate water. The Buckley-Leverett first-order partial differential equation describes the water/oil displacement in each zone.In the absence of capillary and gravitational forces, the water fractional flow Fwo) is given byEq. 1, together with Eq. 2, usually leads to a sharp shock front: at each location, water saturation will instantaneously jump from connate water to shock-front saturation when the water arrives. SPEJ p. 917
8
Kok, M. V., und C. O. Karacan. „Behavior and Effect of SARA Fractions of Oil During Combustion“. SPE Reservoir Evaluation & Engineering 3, Nr. 05 (01.10.2000): 380–85. http://dx.doi.org/10.2118/66021-pa.
Der volle Inhalt der QuelleAnnotation:
Summary In this study, saturate, aromatic, resin, and asphaltene fractions of two Turkish crude oils (medium and heavy) were separated by column chromatographic techniques. Combustion experiments were performed on whole oils and fractions by a thermogravimetric analyzer (TG/DTG) and differential scanning calorimeter (DSC) by using air and a 10°C/min heating rate. TG and DSC data were analyzed for the determination of weight loss due to possible reactions, and for reaction enthalpies of individual fractions, which have to be known for in-situ combustion technology utilization. Introduction In-situ combustion is a process of recovering oil thermally, by igniting the oil to create a combustion front that is propagated through the reservoir by continuous air injection. Success of such a process depends mainly on the crude oil properties and rock properties as well as operational conditions. In-situ combustion is considered as an effective process not only for heavy oil reserves but also for depleted light and medium oil reservoirs. Unfortunately, the lack of better understanding of the process variables in terms of the conversion of oil during combustion and reservoir characteristics, as well as the costs, limits the more effective application of this technology. In combustion, three different reaction regions were identified, known as low-temperature oxidation, fuel deposition, and high-temperature oxidation. In low-temperature oxidation (LTO), mainly small and weak chains of hydrocarbons are broken and pyrolyzed and oxidized to give ketones, alcohols, etc. In fuel deposition or middle-temperature oxidation, products of low-temperature oxidation are transformed to heavier hydrocarbons to be combusted at higher temperatures. High-temperature oxidation (HTO) is the main combustion region where hydrocarbons are fully oxidized by air. During the course of these processes, hydrocarbons are continuously converted to other types of hydrocarbons, which makes the combustion process very complicated. Heat values and reaction parameters of crude oils are also obtained from differential scanning calorimeter (DSC) thermogravimetry (TG/DTG) experiments. Many studies have been conducted on different phases of the in-situ combustion process, mainly on the fluid and rock interactions during combustion of the fluid phase. Vossoughi et al.1 concluded that the addition of clay to porous media significantly affected the combustion of crude oil. Bae2 investigated the thermo-oxidative behavior and fuel forming properties of various crude oils. The results indicated that oils could be classified according to their oxidation characteristics. Vossoughi3 has used TG/DTG and DSC techniques to study the effect of clay and surface area on the combustion of selected oil samples. The results indicate that there was a significant reduction in the activation energy of the combustion reaction regardless of the chemical composition of additives. Vossoughi and Bartlett4 have developed a kinetic model of the in-situ combustion process from thermogravimetry and differential scanning calorimeter. They used the kinetic model to predict fuel deposition and combustion rate in a combustion tube. Kok5 characterized the combustion properties of two heavy crude oils by DSC and TG/DTG. Individual fractions of the crude oils have been studied before in a variety of purposes in different reactions. Ciajolo and Barbella6 used thermogravimetric techniques to investigate the pyrolysis and oxidation of some heavy fuel oils and their separate paraffinic, aromatic, polar, and asphaltene fractions. The thermal behavior of fuel oil can be interpreted in terms of the low-temperature phase in which the polar and asphaltene fractions pyrolyze and leave a particular carbon residue. Ranjbar and Pusch7 studied the effect of oil composition, characterized on the basis of light hydrocarbons, resin, and asphaltene contents, on the pyrolysis kinetics of the oil. The results indicate that the colloidal composition of oil, as well as the transferability and heat transfer characteristics of the pyrolysis medium, has a pronounced influence on the fuel formation and composition. Karacan and Kok8 studied the pyrolysis behavior of crude oil saturate, aromatic, resin, and asphaltene (SARA) fractions to determine the effect of each constituent to the overall pyrolysis behavior of oils. Several authors, such as Geffen,9 Iyoho,10 and Chu11 have conducted feasibility studies for the in-situ combustion process. Yannimaras and Tiffin12 applied the accelerating rate calorimetry to screen crude oils for applicability of the air-injection/in-situ combustion process. Testing was performed at reservoir conditions for four medium and high gravity oils and results were compared with the combustion tube and air-injection/in-situ combustion process on the basis of continuity of the resulting plot in the region between the LTO and HTO reactions. Although combustion studies on both oil samples and oil-rock mixtures had been conducted, studies on the behavior of crude oil SARA fractions under an oxidizing environment and the investigations on the effects of each of these fractions to the whole oil combustion process have been scarce. This research was conducted to fulfill this partial need in the field of crude oil combustion. The results are aimed to serve for better understanding and accurate modeling of in-situ combustion by using the effects of individual fractions on whole oil combustion. This enables the operators to adapt the changes in the compositional properties of oil during combustion and fine tune the operational parameters.
9
Agarwal, A. K. „Experimental investigations of the effect of biodiesel utilization on lubricating oil tribology in diesel engines“. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 219, Nr. 5 (01.05.2005): 703–13. http://dx.doi.org/10.1243/095440705x11239.
Der volle Inhalt der QuelleAnnotation:
Biodiesel is an alternative fuel derived from vegetable oils by modifying their molecular structure through a transesterification process. Linseed oil methyl ester (LOME) was prepared using methanol in the presence of potassium hydroxide as a catalyst. The use of LOME in compression ignition engines was found to develop a very compatible engine-fuel system with lower emission characteristics. Two identical engines were subjected to long-term endurance tests, fuelled by an optimum biodiesel blend (20 per cent LOME) and diesel oil, respectively. Various tribological studies on lubricating oil samples drawn at regular intervals from both engines were conducted in order to correlate the comparative performance of the two fuels and the effect of fuel chemistry on lubricating oil performance and life. A number of tests were conducted in order to evaluate the comparative performances of the two fuels such as density measurement, viscosity measurements, Flashpoint determination, moisture content determination, pentane and benzene insolubles, thin layer chromatography, differential scanning calorimetry, etc. All these tests were used for an indirect interpretation of the comparative performance of these fuels. The performance of biodiesel fuel is found to be superior to that of diesel oil and the lubricating oil life is found to be longer while operating the engine on biodiesel
10
Różańska, Maria Barbara, Przemysław Łukasz Kowalczewski, Jolanta Tomaszewska-Gras, Krzysztof Dwiecki und Sylwia Mildner-Szkudlarz. „Seed-Roasting Process Affects Oxidative Stability of Cold-Pressed Oils“. Antioxidants 8, Nr. 8 (16.08.2019): 313. http://dx.doi.org/10.3390/antiox8080313.
Der volle Inhalt der QuelleAnnotation:
The oxidative stability of vegetable oils mainly depends on their fatty acid composition, their degree of unsaturation, and the presence of compounds with antioxidant activity. This paper reports on the effects of the process of roasting oil seeds, prior to pressing them, on the basic characteristics of the oils produced and their oxidative stability. The differential scanning calorimetry (DSC) technique was used to study the process of oxidation of the oil samples in an oxygen-flow cell. Chromatographic analysis revealed that roasting the seeds increased the levels of chlorophyll and β-carotene in all the cold-pressed oils. Similar results were observed for the oil’s antioxidant activity, measured by the scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical method. Our results also indicated that roasting seeds prior to pressing them for oil had a positive effect on the oil’s stability, as determined by the DSC method. This manifested in both the extension of oxidation induction time and the final oxidation time.
11
Yuan, Hemin, De-Hua Han, Luanxiao Zhao, Qi Huang und Weimin Zhang. „Attenuation analysis of heavy oil sands based on laboratory measurements“. GEOPHYSICS 84, Nr. 5 (01.09.2019): B299—B309. http://dx.doi.org/10.1190/geo2018-0171.1.
Der volle Inhalt der QuelleAnnotation:
Analyzing elastic and attenuation characteristics of heavy oil sand is critical for understanding and interpreting sonic and seismic data for their use in exploration and reservoir monitoring. The attenuation characteristic of oil sands is inherently complicated because of its loose frame, large porosity, and highly temperature-dependent viscosity of heavy oil. During thermal production, the attenuation of heavy oil sands undergoes significant changes due to the effects of pressure, temperature, and gas. Therefore, we have performed laboratory measurements of heavy oil sands under different physical conditions. By applying spectral-ratio method on the recorded wave signals, we are able to investigate the attenuation of the oil sands under different pressure and temperature conditions. For the measured sample, the [Formula: see text] decreases from 0.083 to 0.043 for a differential pressure increasing from 1.38 to 9.65 MPa. A peak of [Formula: see text] occurs at the middle temperature (approximately 60°C) for the wet sample, whereas the weakest [Formula: see text] occurs at the low temperature. Comparisons between the as-is (partially saturated) and wet (fully saturated) samples suggest that attenuation ([Formula: see text]) of the oil sands can be significantly affected by the presence of gas at a high temperature (greater than 60°C). In the end, the Havriliak-Negami model is used to capture the temperature-dependent attenuation characteristics of fully saturated oil sands. Although the measurements are conducted at ultrasonic frequency, the presented results indicate some implications for field-reservoir monitoring and also offer insights into applying attenuation attribute to characterize heavy oil reservoir during thermal production.
12
Ma, Qi Qi, und Yan Chun Wang. „The Research of Forward Modeling about Seismic Attributes in Rich Oil Reservoir Segment of Enping Sag“. Advanced Materials Research 1065-1069 (Dezember 2014): 1547–50. http://dx.doi.org/10.4028/www.scientific.net/amr.1065-1069.1547.
Der volle Inhalt der QuelleAnnotation:
Enping sag is located in the west of Zhu 1 sag of Pearl River Mouth Basin. In order to verify the reservoir spreading of Enping sag in Pearl River Mouth Basin and provide the reliable basis for reserves prediction. In this paper, according to the actual seismic data extracting the theoretical seismic model, applying spectral method to construct the acoustic wave equation, and then, deducing the partial differential equation resolution of absorbing boundary condition. Through the forward modeling summarized the seismic response characteristics of oil layer, and making a forward modeling with actual parameters of wells model. Finally obtained the expected effect.
13
Zhao, Jiawen, Kening Jiang, Yixuan Chen, Juan Chen, Yangfan Zheng, Huilin Yu und Jiajin Zhu. „Preparation and Characterization of Microemulsions Based on Antarctic Krill Oil“. Marine Drugs 18, Nr. 10 (25.09.2020): 492. http://dx.doi.org/10.3390/md18100492.
Der volle Inhalt der QuelleAnnotation:
Antarctic krill oil is high in nutritional value and has biological functions like anti-inflammation and hypolipidemic effects. But it has and unpleasant smell, and unsaturated fatty acids are prone to oxidative deterioration. Its high viscosity and low solubility in water make it difficult for processing. Microemulsion can be a new promising route for development of krill oil product. We determined a formula of krill oil-in-water microemulsion with krill oil: isopropyl myristate = 1:3 as oil phase, Tween 80:Span 80 = 8:2 as surfactant, ethanol as co-surfactant and the mass ratio of surfactant to co-surfactant of 3:1. After screening the formula, we researched several characteristics of the prepared oil-in-water microemulsion, including electrical conductivity, microstructure by transmission electron microscope and cryogenic transmission electron microscope, droplet size analysis, rheological properties, thermal behavior by differential scanning calorimeter and stability against pH, salinity, and storage time.
14
Zhang, Penggao, Boqin Gu, Jianfeng Zhou und Long Wei. „On hydrodynamic lubrication characteristics of ferrofluid film in a spiral groove mechanical seal“. Industrial Lubrication and Tribology 70, Nr. 9 (19.11.2018): 1783–97. http://dx.doi.org/10.1108/ilt-07-2017-0186.
Der volle Inhalt der QuelleAnnotation:
Purpose The purpose of this study is to investigate the hydrodynamic lubrication characteristics of ferrofluid film for spiral groove mechanical seal in external electromagnetic field and to analyze the effects of the volume fraction of ferrofluid, parameters of the electromagnetic field, operating parameters and geometrical parameters of mechanical seal on the characteristics of ferrofluid film. Design/methodology/approach The relationship between the ferrofluid viscosity and the intensity of external electromagnetic field was established. Based on the Muijderman narrow groove theory, the pressure distribution was calculated with the trial method by trapezoid formula. Findings It was found that pressure, average viscosity, average density and opening force of ferrofluid between end faces increase with the increase in intensity of current, volume fraction of ferrofluid, rotating speed, pressure differential and spiral angle; decrease with the increase in temperature; and increase at first and then decrease with the increase in the ratio of groove width to weir and the groove length. All of them reach the maximum value when the ratio of width of groove to weir is 0.7 and the ratio of groove length is 0.6. Leakage of ferrofluid increases with an increase in intensity of current, volume fraction of ferrofluid, rotating speed, pressure differential, spiral angle and ratio of groove length; decreases with an increase in temperature; and increases at first and then decreases with the increase in the ratio of groove width to weir. The tendencies of characteristics of silicone oil are consistent with those of ferrofluid, and the characteristics of silicone oil are smaller than those of ferrofluid under the same condition. Originality/value The volume fraction of ferrofluid, rotating speed, spiral angle, ratio of groove width to weir, groove length and temperature have a significant influence on the characteristics of ferrofluid film; however, intensity of current and the pressure differential have slight influence on the characteristics of ferrofluid film. An analytical method for analyzing hydrodynamic lubrication characteristics of ferrofluid film in a spiral groove mechanical seal was proposed based on the Muijderman narrow groove theory.
15
Yang, Jian Jun, Wei Sheng Guai und Hong Rong Che. „Study on Thermogravimetry and Pyrolysis Dynamics of Tung Oil“. Advanced Materials Research 524-527 (Mai 2012): 1719–22. http://dx.doi.org/10.4028/www.scientific.net/amr.524-527.1719.
Der volle Inhalt der QuelleAnnotation:
In this paper, Tung oil from the south of Shaanxi province was assayed, and the behavior of its thermal decomposition was investigated by thermogravimetry. The pyrolysis characteristics of Tung oil experimentally studied using thermo-gravimetric analyzer (TGA).The TG curves and DTG curves were examined under different operating conditions such as heating rate and different atmospheres. The mechanism equation of pyrolysis reaction, activation energy (E) and frequency factor (A) were obtained by using differential method to fit experimental data. The experimental results shown that there are two temperature ranges in the organic matter pyrolysis period: 350-420°C and 420-500°C in air, but 350-450°C in nitrogen. The effects on Tung oil pyrolysis of different heating rates were indistinct. The activation energy in the first period was more than that in the second period.
16
Zhang, Shi Min. „The Experimental Research of the Restricting Factors of Water Invasion of Yulou Reservoir in Jin 45 Block“. Advanced Materials Research 838-841 (November 2013): 1655–58. http://dx.doi.org/10.4028/www.scientific.net/amr.838-841.1655.
Der volle Inhalt der QuelleAnnotation:
Jin 45 block has entered the later period of cyclic steam, Transforming the development mode is imminent,there is a big technical risks in the development of cyclic steam of edge and bottom water of heavy oil when it turns to steam flooding development, it is needed to understand the characteristics of Edge-bottom water which invades in reservoir and master the restricting factors of invasion of the edge-bottom water,to avoid the risk of steam flooding development reasonably and effectively. The experiment uses the three layers of inhomogeneous Artificial core which has high permeability transition zone of simulative edge water on the edge. Analysis the factors of differential pressure, temperature and distance of the water and bottom water to the effect of Edge-bottom water encroachment sensitivity. The results show that: Among many factors of water encroachment sensitivity, the effect of differential pressure to the regularity of water invasion is most obvious, at the stage of Connection of water invasion, the differential pressure has a little effect on the Instantaneous water influx, After the channel of water encroachment has formed,Instantaneous water rate and differential pressure is index function relation, in the late of water invasion, the instantaneous water rate is stable. The result provides the basis for the heavy waterflooded area turn to steam flooding.
17
Liu, Wu, Mingcai Shu, Yongyao Sun und Yuanbo Fan. „Flow Field Numerical Simulation and Performance Analysis of Progressing Cavity Pump“. SPE Production & Operations 36, Nr. 02 (24.03.2021): 343–58. http://dx.doi.org/10.2118/205359-pa.
Der volle Inhalt der QuelleAnnotation:
Summary Progressing cavity pump (PCP) is the essential booster equipment in oil–gas mixing delivery. Changes in relevant parameters in PCP operations directly affect the working performance and service life of the pump. On the basis of computational fluid dynamics (CFD) in this study, we apply dynamic grid technology to establish a 3D flow field numerical calculation model for the CQ11-2.4J PCP, which is used in the field of the Hounan Operation Area in Changqing oil field, China. The effects of several operating parameters, such as oil viscosity, pump rotation speed, differential pump pressure, and void fraction of oil, on the pressure and the velocity distribution of the PCP flow field are examined. Various performance parameters in the transport of the oil–gas two-phase mixture are used in the analysis, including volumetric flow rate, slippage, shaft power, volumetric efficiency, and system efficiency. The results show that the pressure and speed distribution in the pump chamber of the PCP is relatively homogenous under different working conditions, whereas the pressure and speed exhibited sharp changes at the stator and rotor sealing line and adjacent areas in the pump chamber. Increasing the viscosity of the oil and the speed of the rotor can effectively improve the flow characteristics of the PCP, but extremely high pump rotation speed would cause a decline in system efficiency. Increasing the differential pressure and the void fraction of oil would result in a decrease in the volumetric flow rate and efficiency of the PCP. Considering the variation law of the PCP's performance parameters, the optimal interval for each operating parameter of the PCP is as follows: Oil viscosity at 50–100 mPa·s, pump rotation speed at 200–300 rev/min, differential pressure at 0.2–0.3 MPa, and the void fraction of oil not more than 50%. This research can provide technical support for the optimization of the working conditions of the PCP on site.
18
Setiawan, Iwan, Diah Indira und Angsoka Yorintha Paundralingga. „PEMBAYARAN PINJAMAN LUAR NEGERI KORPORASI DAN PERGERAKAN RUPIAH“. Buletin Ekonomi Moneter dan Perbankan 9, Nr. 3 (03.08.2007): 31–72. http://dx.doi.org/10.21098/bemp.v9i3.208.
Der volle Inhalt der QuelleAnnotation:
The shifting of the exchange rate regime toward the free floating system in Indonesia, have changed the nature of the Indonesian Rupiah fluctuation, both in its magnitude and direction. Public opinion tends to believe that the high corporate demand on foreign exchange to fulfill their foreign debt repayment is one of the major depreciating factors of the Rupiah against the US dollar.This paper analyzes the response of public opinion by analyzing the effect of corporate foreign debt repayments and their general behavior on the foreign exchange demand and supply. This paper also analyzes the impact of the non-oil and gas imports, the international oil price, the interest rate differential, and the country risk.Based on the survey of selected highly leverage corporates in Indonesia, the result shows a unique dependency of the corporate»s foreign exchange demand and supply on the corporate»s earning characteristics and its business sector orientation. The fact that corporations are virtually in the position of excess demand for foreign exchange have prompted persistent pressure on the Rupiah. Furthermore, using the Johansen Cointegration Test and the Error Correction Model verifies that the corporate foreign debt service merely affects the Rupiah exchange rate in the long-run. In the short-run, the movement of Rupiah is highly affected by other factors such us the global oil price, interest rate differentials, and country risks.Keyword: Debt Service, exchange rate, cointegration, Error Correction Model, Indonesia.JEL Classification: JEL Classification: F31, F34, H63
19
Rahman, Mohammad M., und Mohammed M. Al-Hatmi. „Hydromagnetic Boundary Layer Flow and Heat Transfer Characteristics of a Nanofluid over an Inclined Stretching Surface in the Presence of a Convective Surface: A Comprehensive Study“. Sultan Qaboos University Journal for Science [SQUJS] 19, Nr. 2 (01.02.2015): 53. http://dx.doi.org/10.24200/squjs.vol19iss2pp53-76.
Der volle Inhalt der QuelleAnnotation:
In this paper we investigate numerically the hydromagnetic boundary layer flow and heat transfer characteristics of a nanofluid using three types of nanoparticles (copper, aluminium oxide and titanium dioxide) having various shapes (spherical, cylindrical, arbitrary, etc) by considering three kinds of base fluids (water, ethylene glycol and engine oil) over a nonlinear inclined stretching surface, taking into account the effect of convective surface condition. Using similarity transformations, the governing nonlinear partial differential equations of the physical model are transformed into non-dimensional ordinary differential equations which are solved for local similar solutions using the very robust computer algebra software, Maple 13. The numerical simulation is carried out to investigate the role of the pertinent parameters on the flow and temperature fields as well as on the rate of heat transfer and on the rate of shear stress. The results show that the addition of nanoparticles to the base fluid may not always increase the rate of heat transfer. It depends significantly on the surface convection, type of base fluid and nanoparticles. The finding of this study will open a gate for better understanding of nanofluid characteristics.
20
Kayukova, Galina P., Anastasiya N. Mikhailova, Igor P. Kosachev, Dmitry A. Emelyanov, Mikhail A. Varfolomeev, Boris V. Uspensky und Alexey V. Vakhin. „The Oil-Bearing Strata of Permian Deposits of the Ashal’cha Oil Field Depending on the Content, Composition, and Thermal Effects of Organic Matter Oxidation in the Rocks“. Geofluids 2020 (24.02.2020): 1–19. http://dx.doi.org/10.1155/2020/6304547.
Der volle Inhalt der QuelleAnnotation:
The features of the oil-bearing capacity of the productive strata of Permian deposits in the interval of 117.5-188.6 m along the section of individual wells of the Ashal’cha field of heavy superviscous oil (Tatarstan) were revealed depending on the content, composition, and thermal effects of organic matter (OM) oxidation in the rocks. It is shown that the rocks are very heterogeneous in their mineral composition and in the content of both free hydrocarbons by extraction with organic solvents and insoluble OM closely associated with the rock. The total content of OM in rocks varies from 1.72 to 9.12%. The features of group and hydrocarbon composition of extracts from rocks are revealed depending on their mineral composition and the content of organic matter in them. According to the molecular mass distribution of alkanes of normal and isoprenoid structure, extracts from rocks are differentiated according to three chemical types of oil: type A1, in which n-alkanes of composition C14 and above are present, and types A2 and B2, in which n-alkanes are destroyed to varying degrees by processes microbial destruction, which indicates a different intensity of biochemical processes in productive strata of Permian sediments. These processes lead to a decrease in the amount of OM in the rocks and an increase in the content of resins and asphaltenes in the oil extracted from them, as well as an increase in the viscosity of the oil. Using the method of differential scanning calorimetry of high pressure, it was found that the studied rock samples differ from each other in quantitative characteristics of exothermic effects in both low-temperature (LTO) 200-350°С and high-temperature (HTO) 350-600°С zones of OM oxidation. The total thermal effect of destruction processes of OM depends on the content of OM in the rocks and its composition. The research results show that when heavy oil is extracted using thermal technologies, the Permian productive strata with both low and high OM contents will be involved in the development, and the general thermal effect of the oxidation of which will contribute to increased oil recovery.
21
Karthik, T. S., K. Loganathan, A. N. Shankar, M. Jemimah Carmichael, Anand Mohan, Mohammed K. A. Kaabar und Safak Kayikci. „Zero and Nonzero Mass Flux Effects of Bioconvective Viscoelastic Nanofluid over a 3D Riga Surface with the Swimming of Gyrotactic Microorganisms“. Advances in Mathematical Physics 2021 (16.07.2021): 1–13. http://dx.doi.org/10.1155/2021/9914134.
Der volle Inhalt der QuelleAnnotation:
This work addresses 3D bioconvective viscoelastic nanofluid flow across a heated Riga surface with nonlinear radiation, swimming microorganisms, and nanoparticles. The nanoparticles are tested with zero (passive) and nonzero (active) mass flux states along with the effect of thermophoresis and Brownian motion. The physical system is visualized via high linearity PDE systems and nondimensionalized to high linearity ordinary differential systems. The converted ordinary differential systems are solved with the aid of the homotopy analytic method (HAM). Several valuable and appropriate characteristics of related profiles are presented graphically and discussed in detail. Results of interest such as the modified Hartmann number, mixed convection parameter, bioconvection Rayleigh number, and Brownian motion parameter are discussed in terms of various profiles. The numerical coding is validated with earlier reports, and excellent agreement is observed. The microorganisms are utilized to improve the thermal conductivity of nanofluid, and this mechanism has more utilization in the oil refinery process.
22
Aiduganov, Dmitrii, Dinar Balkaev, Mikhail Varfolomeev und Dmitrii Emelianov. „Effect of formation water and hydrochloric acid on the physical and chemical properties of polymer materials of high pressure pipelines used for transportation of crude oil“. E3S Web of Conferences 121 (2019): 04001. http://dx.doi.org/10.1051/e3sconf/201912104001.
Der volle Inhalt der QuelleAnnotation:
The purpose of the work is to conduct a comparative analysis of the stability of two types of polymer coatings to the effects of formation water and hydrochloric acid based on the analysis of mechanical properties, thermal stability and surface morphology. To accomplish the task, modern physical-chemical methods were used: differential scanning calorimetry, microscopy, an electromechanical universal testing machine, a dilatometer. Simulation of the effect of water at elevated temperatures and pressures on the polymer coating samples was carried out in an autoclave-reactor, the study of the effect of acid was carried out in a glass beaker. On the basis of the work carried out, results were obtained that show similarities and differences in the behavior of the polymer samples studied. The change of the dynamic modulus of elasticity and the coefficient of linear thermal expansion with increasing temperature is investigated. In general, it has been shown that PE-RT polymer has better characteristics than PE polymer. However, both of them are stable to the exposure of formation water and hydrochloric acid and can protect corrosion of high pressure pipes connections.
23
Shahverdi, H., und M. Sohrabi. „Relative Permeability Characterization for Water-Alternating-Gas Injection in Oil Reservoirs“. SPE Journal 21, Nr. 03 (15.06.2016): 0799–808. http://dx.doi.org/10.2118/166650-pa.
Der volle Inhalt der QuelleAnnotation:
Summary Large quantities of oil usually remain in oil reservoirs after conventional waterfloods. A significant part of this remaining oil can still be economically recovered by water-alternating-gas (WAG) injection. WAG injection involves drainage and imbibition processes taking place sequentially; therefore, the numerical simulation of the WAG process requires reliable knowledge of three-phase relative permeability (kr) accounting for cyclic-hysteresis effects. In this study, the results of a series of unsteady-state two-phase displacements and WAG coreflood experiments were used to investigate the behavior of three-phase kr and hysteresis effects in the WAG process. The experiments were performed on two different cores with different characteristics and wettability conditions. An in-house coreflood simulator was developed to obtain three-phase relative permeability values directly from unsteady-state WAG experiments by history matching the measured recovery and differential-pressure profiles. The results show that three-phase gas relative permeability is reduced in consecutive gas-injection cycles and consequently the gas mobility and injectivity drop significantly with successive gas injections during the WAG process, under different rock conditions. The trend of hysteresis in the relative permeabilty of gas (krg) partly contradicts the existing hysteresis models available in the literature. The three-phase water relative permeability (krw) of the water-wet (WW) core does not exhibit considerable hysteresis effect during different water injections, whereas the mixed-wet (MW) core shows slight cyclic hysteresis. This may indicate a slight increase of the water injectivity in the subsequent water injections in the WAG process under MW conditions. Insignificant hysteresis is observed in the oil relative permeability (kro) during different gas-injection cycles for both WW and MW rocks. However, a considerable cyclic-hysteresis effect in kro is observed during water-injection cycles of WAG, which is attributed to the reduction of the residual oil saturation (ROS) during successive water injections. The kro of the WW core exhibits much-more cyclic-hysteresis effect than that of the MW core. No models currently exist in reservoir simulators that can capture the observed cyclic-hysteresis effect in oil relative permeability for the WAG process. Investigation of relative permeability data obtained from these displacement tests at different rock conditions revealed that there is a significant discrepancy between two-phase and three-phase relative permeability of all fluids. This highlights that not only the three-phase relative permeability of the intermediate phase (oil), but also the three-phase kr of the wetting phase (water) and nonwetting phase (gas) are functions of two independent saturations.
24
Zhu, Jianhong, Junbin Chen, Xiaoming Wang, Lingyi Fan und Xiangrong Nie. „Experimental Investigation on the Characteristic Mobilization and Remaining Oil Distribution under CO2 Huff-n-Puff of Chang 7 Continental Shale Oil“. Energies 14, Nr. 10 (12.05.2021): 2782. http://dx.doi.org/10.3390/en14102782.
Der volle Inhalt der QuelleAnnotation:
The Chang 7 continental shale oil reservoir is tight. The recovery factor is extremely low, the remaining oil is very high, and injecting water to improve oil recovery effectiveness is too hard. Therefore, in this paper, physical simulation experiments of CO2 huff-n-puff shale oil and NMR tests were conducted to study the cycle numbers and permeability on the recovery degree, as well as the characteristics of shale oil mobilization and the remaining oil micro distribution. The results showed that the cumulative oil recovery factors (ORFs) gradually increased in the natural logarithmic form, the single cycle ORFs decreased rapidly in exponential form with the huff-n-puff cycle number, and the biggest economic cycle numbers were between approximately 3 and 5. Furthermore, the higher the permeability, the higher the ORF, but the difference of ORF decreased between the two experimental samples with the cycles. In addition, the gap of production and recovery degree was large between the different scale pores, the ORF of macropores was 6–8 times that of micropores, and the final remaining oil was mainly distributed in the micropores, accounting for 82.29% of the total amount; meanwhile, the macropores comprised less than 0.5%. In the process of huff-n-puff, CO2 flowed into macropores, mesopores, and smallpores under the pressure differential effect, but a small amount of CO2 slowly diffused into micropores, resulting in the ORF of the former with more free oil being higher and the ORF of micropores with more adsorbed oil being lower. Therefore, promoting a better contact and reaction between CO2 and shale oil of micropores is one of the key ways to effectively develop the Chang 7 continental shale oil and enhance oil recovery.
25
Ahmed, Zeeshan, Junhe Liu, Ejaz Ahmad Waraich, Yan Yan, Zhiming Qi, Dongwei Gui, Fanjiang Zeng et al. „Differential physio-biochemical and yield responses of Camelina sativa L. under varying irrigation water regimes in semi-arid climatic conditions“. PLOS ONE 15, Nr. 12 (02.12.2020): e0242441. http://dx.doi.org/10.1371/journal.pone.0242441.
Der volle Inhalt der QuelleAnnotation:
Camelina sativa L. is an oilseed crop with wide nutritional and industrial applications. Because of favorable agronomic characteristics of C. sativa in a water-limiting environment interest in its production has increased worldwide. In this study the effect of different irrigation regimes (I0 = three irrigations, I1 = two irrigations, I2 = one irrigation and I3 = one irrigation) on physio-biochemical responses and seed yield attributes of two C. sativa genotypes was explored under semi-arid conditions. Results indicated that maximum physio-biochemical activity, seed yield and oil contents appeared in genotype 7126 with three irrigations (I0). In contrast water deficit stress created by withholding irrigation (I1, I2 and I3) at different growth stages significantly reduced the physio-biochemical activity as well as yield responses in both C. sativa genotypes. Nonetheless the highest reduction in physio-biochemical and yield attributes were observed in genotype 8046 when irrigation was skipped at vegetative and flowering stages of crop (I3). In genotypic comparison, C. sativa genotype 7126 performed better than 8046 under all I1, I2 and I3 irrigation treatments. Because 7126 exhibited better maintenance of tissue water content, leaf gas exchange traits and chlorophyll pigment production, resulting in better seed yield and oil production. Findings of this study suggest that to achieve maximum yield potential in camelina three irrigations are needed under semi-arid conditions, however application of two irrigations one at flowering and second at silique development stage can ensure an economic seed yield and oil contents. Furthermore, genotype 7126 should be adopted for cultivation under water limited arid and semi-arid regions due to its better adaptability.
26
Kim, Hyeongmin, Sukkyun Jung, Sooho Yeo, Dohyun Kim, Young Chae Na, Gyiae Yun und Jaehwi Lee. „Characteristics of Skin Deposition of Itraconazole Solubilized in Cream Formulation“. Pharmaceutics 11, Nr. 4 (22.04.2019): 195. http://dx.doi.org/10.3390/pharmaceutics11040195.
Der volle Inhalt der QuelleAnnotation:
Itraconazole (ITZ) is an anti-fungal agent generally used to treat cutaneous mycoses. For efficient delivery of ITZ to the skin tissues, an oil-in-water (O/W) cream formulation was developed. The O/W cream base was designed based on the solubility measurement of ITZ in various excipients. A physical mixture of the O/W cream base and ITZ was also prepared as a control formulation to evaluate the effects of the solubilized state of ITZ in cream base on the in vitro skin deposition behavior of ITZ. Polarized light microscopy and differential scanning calorimetry demonstrated that ITZ was fully solubilized in the O/W cream formulation. The O/W cream formulation exhibited considerably enhanced deposition of ITZ in the stratum corneum, epidermis, and dermis compared with that of the physical mixture, largely owing to its high solubilization capacity for ITZ. Therefore, the O/W cream formulation of ITZ developed in this study is promising for the treatment of cutaneous mycoses caused by fungi such as dermatophytes and yeasts.
27
Nooripoor, Vahid, und Abdolnabi Hashemi. „Effect of a modified nano clay and nano graphene on rheology, stability of water-in-oil emulsion, and filtration control ability of oil-based drilling fluids: a comparative experimental approach“. Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles 75 (2020): 40. http://dx.doi.org/10.2516/ogst/2020032.
Der volle Inhalt der QuelleAnnotation:
During the past decade, researchers have used different Nano-Particles (NPs) due to their unique characteristics for improving formulation of Oil-Based Drilling Fluids (OBDFs). This study is the first research that investigates the effect of a Modified Nano Clay (MNC), namely CLOISITE 5 and non-functionalized Nano Graphene (NG) on rheology, electrical/emulsion stability, and filtration control ability, as the main properties of OBDFs. Initially, five concentrations of both NPs (0.25, 0.5, 1, 1.5, and 2 wt%) were added separately into an NP-free OBDF (the base fluid). Then, rheological properties and electrical stability of all prepared fluids were measured at three 90, 140, and 180 °F temperatures. Moreover, filtration test was carried out under 500 psi (3447 kPa) differential pressure and exposed to 300 °F temperature for all fluids. Since experimentally measured shear stresses followed well both Herschel Bulkley (shear-thinning) and Bingham Plastic models, effects of temperature and the NPs concentration on both model parameters are investigated more deeply in the paper. Activation energies calculated from Arrhenius model showed that MNC is more effective than NG on reducing the dependency of apparent and plastic viscosities of the base fluid on temperature. MNC, due to its amphiphilic structure, significantly stabilizes water-in-oil emulsion at all temperatures and concentrations, but NG with high electrical conductivity reduces the emulsion stability. The nanofluids containing 0.5 wt% MNC and 0.25 wt% NG which have respectively 32.6% and 43.5% fewer filtrate volumes than the base fluid, were considered as the optimal nanofluids from controlling filtration into formation aspect. Finally, MNC is applicable to enhance the formulation of the OBDF through supporting its commercial viscosifier, emulsifiers, and fluid loss control agent, but the negative effect of NG on emulsion stability limits its application.
28
Andrade-Ochoa, Sergio, Karla Fabiola Chacón-Vargas, Luvia Enid Sánchez-Torres, Blanca Estela Rivera-Chavira, Benjamín Nogueda-Torres und Guadalupe Virginia Nevárez-Moorillón. „Differential Antimicrobial Effect of Essential Oils and Their Main Components: Insights Based on the Cell Membrane and External Structure“. Membranes 11, Nr. 6 (28.05.2021): 405. http://dx.doi.org/10.3390/membranes11060405.
Der volle Inhalt der QuelleAnnotation:
The biological activity of essential oils and their major components is well documented. Essential oils such as oregano and cinnamon are known for their effect against bacteria, fungi, and even viruses. The mechanism of action is proposed to be related to membrane and external cell structures, including cell walls. This study aimed to evaluate the biological activity of seven essential oils and eight of their major components against Gram-negative and Gram-positive bacteria, filamentous fungi, and protozoans. The antimicrobial activity was evaluated by determination of the Minimal Inhibitory Concentration for Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, Salmonella Typhimurium, Shigella sonnei, Aspergillus niger, Aspergillus ochraceus, Alternaria alternata, and Fusarium oxysporium, the half-maximal inhibitory concentration (IC50) for Trypanosoma cruzi and Leishmania mexicana, and the median lethal dose (LD50) for Giardia lamblia. Results showed that oregano essential oil showed the best antibacterial activity (66–100 µg/mL), while cinnamon essential oil had the best fungicidal activity (66–116 µg/mL), and both showed excellent antiprotozoal activity (22–108 µg/mL). Regarding the major components, thymol and carvacrol were also good antimicrobials (23–200 µg/mL), and cinnamaldehyde was an antifungal compound (41–75 µg/mL). The major components were grouped according to their chemical structure as phenylpropanoids, terpenoids, and terpinenes. The statistical analysis of the grouped data demonstrated that protozoans were more susceptible to the essential oils, followed by fungi, Gram-positive bacteria, and Gram-negative bacteria. The analysis for the major components showed that the most resistant microbial group was fungi, which was followed by bacteria, and protozoans were also more susceptible. Principal Component Analysis for the essential oils demonstrated the relationship between the biological activity and the microbial group tested, with the first three components explaining 94.3% of the data variability. The chemical structure of the major components was also related to the biological activity presented against the microbial groups tested, where the three first principal components accounted for 91.9% of the variability. The external structures and the characteristics of the cell membranes in the different microbial groups are determinant for their susceptibility to essential oils and their major components
29
Yu, Guang, und Boyang Yu. „The Effect of the Cooling Process on the Crystalline Morphology and Dielectric Properties of Polythene“. Materials 13, Nr. 12 (20.06.2020): 2791. http://dx.doi.org/10.3390/ma13122791.
Der volle Inhalt der QuelleAnnotation:
In this study, LDPE samples were prepared by melt blending with different cooling processes, which were natural air cooling, rapid air cooling, water cooling and oil cooling, respectively. According to polarization microscope (PLM) and differential scanning calorimeter (DSC) tests of these four low-density polyethylene (LDPE) samples, the effect of different cooling processes on polythene crystalline morphology could be studied. According to conductivity, dielectric frequency spectra and space charge tests, the effect of crystalline morphology on dielectric macroscopic properties could be explored. The microstructure characteristic results indicated the cooling medium significantly affected polythene crystalline morphology. When the samples were produced with natural air cooling, the crystalline grain size was large. On the other hand, after rapid air cooling, water cooling and oil cooling processes, the samples’ crystalline grain dispersed uniformly, and the grain sizes were lower. The space charge testing results indicate the samples produced with water cooling and oil cooling processes restrained the electrode injection in the process of pressurization. During short-circuits, the rates of charge release of these two samples were fast, and the remaining space charges were fewer. The conductivity and dielectric frequency spectra testing results indicated the conductivities of samples produced with water cooling and oil cooling processes were both less than those of samples produced with a natural air cooling process. Besides, with increasing experimental frequency, the relative dielectric constants of all testing samples decreased. Among them, the relative dielectric constant of the LDPE sample with the natural air cooling process was the largest. However, the crystalline structures of samples produced with rapid air cooling and water cooling processes were close, which restrained the movement of polymer macromolecule chains. Thus, the dielectric constants were lower. Additionally, because of the influence of relaxation polarization and dipole polarization, the dielectric losses of LDPE with water cooling and oil cooling processes increased to varying degrees.
30
González-Reza, Ricardo M., Humberto Hernández-Sánchez, Maria L. Zambrano-Zaragoza, Gustavo F. Gutiérrez-López, Alicia Del-Real, David Quintanar-Guerrero und Benjamín Velasco-Bejarano. „Influence of Stabilizing and Encapsulating Polymers on Antioxidant Capacity, Stability, and Kinetic Release of Thyme Essential Oil Nanocapsules“. Foods 9, Nr. 12 (17.12.2020): 1884. http://dx.doi.org/10.3390/foods9121884.
Der volle Inhalt der QuelleAnnotation:
The release kinetics, stability, and antioxidant capacity of thyme essential oil polymeric nanocapsules as a function of encapsulating (poly-ε-caprolactone and ethylcellulose) and stabilizing (polyvinyl alcohol and Pluronic® F-127) polymers were established. Samples were evaluated in terms of particle size, zeta potential, release kinetics, calorimetry, infrared spectra, antioxidant capacity, and diffuse reflectance. The particle size obtained was below 500 nm in all cases, ensuring nanometric size. Zeta potential as a function of the stabilizing polymer. Encapsulation efficiency was higher in the samples that contained ethyl cellulose (around 70%), associated with its affinity for the molecules contained in the essential oil. Differential scanning calorimetry revealed a strong dependence on the encapsulating polymers as a function of the melting temperatures obtained. Infrared spectra confirmed that the polymeric nanocapsules had the typical bands of the aromatic groups of thyme essential oil. The antioxidant capacity evaluated is a function exclusively of the active content in the nucleolus of the nanocapsules. Nanoencapsulation was not a significant factor. Diffuse reflectance revealed high physical stability of the dispersions related directly to the particle size and zeta potential obtained (either by ionic or steric effect). These findings confirm favorable characteristics that allow proposing these systems for potential applications in food processing and preservation.
31
Mena, Carmen, Alejandra Z. González, Raúl Olivero-David und María Ángeles Pérez-Jiménez. „Characterization of ‘Castellana’ Virgin Olive Oils with Regard to Olive Ripening“. HortTechnology 28, Nr. 1 (Februar 2018): 48–57. http://dx.doi.org/10.21273/horttech03845-17.
Der volle Inhalt der QuelleAnnotation:
The production of high-quality virgin olive oil from traditional olive (Olea europaea L.) varieties with peculiar and differential characteristics is of great interest for the olive oil market. ‘Castellana’ is an autochthonous variety mainly located in the center of Spain. The aims of this study were 1) the characterization of ‘Castellana’ virgin olive oils and 2) the evaluation of the influence of fruit ripening degree on the oil quality to establish an optimum harvest time for ‘Castellana’ olives. A wide range of physicochemical and sensorial quality parameters were assayed in oils produced at four harvest times during three crop seasons. ‘Castellana’ oils could be classified into the extra virgin category at all ripening degrees studied. This variety provides well-balanced oils from the sensorial point of view with an optimum chemical composition. Nevertheless, fruit maturation had a strong effect in various quality parameters, especially total phenol content, total tocopherol content, sensorial quality, and to a lesser extent in fatty acid composition. Loss of antioxidants and decrease in sensorial quality take place during olive ripening, reducing the nutritional, sensorial, and commercial quality of virgin olives oils as the harvest is delayed. Results suggest that the production of optimal extra virgin olive oil requires that ‘Castellana’ olives should be harvested from the middle of November to the middle of December, coinciding with a ripening index between 3.1 and 4.1. These results are of great importance to the olive oil industry for improving the quality of virgin olive oils produced from ‘Castellana’.
32
Duan, Huiming, Guang Rong Lei und Kailiang Shao. „Forecasting Crude Oil Consumption in China Using a Grey Prediction Model with an Optimal Fractional-Order Accumulating Operator“. Complexity 2018 (01.08.2018): 1–12. http://dx.doi.org/10.1155/2018/3869619.
Der volle Inhalt der QuelleAnnotation:
Crude oil, which is an important part of energy consumption, can drive or hinder economic development based on its production and consumption. Reasonable predictions of crude oil consumption in China are meaningful. In this paper, we study the grey-extended SIGM model, which is directly estimated with differential equations. This model has high simulation and prediction accuracies and is one of the important models in grey theory. However, to achieve the desired modeling effect, the raw data must conform to a class ratio check. Unfortunately, the characteristics of the Chinese crude oil consumption data are not suitable for SIGM modeling. Therefore, in this paper, we use a least squares estimation to study the parametric operation properties of the SIGM model, and the gamma function is used to extend the integer order accumulation sequence to the fractional-order accumulation generation sequence. The first-order SIGM model is extended to the fractional-order FSIGM model. According to the particle swarm optimization (PSO) mechanism and the properties of the gamma function of the fractional-order cumulative generation operator, the optimal fractional-order particle swarm optimization algorithm of the FSIGM model is obtained. Finally, the data concerning China’s crude oil consumption from 2002 to 2014 are used as experimental data. The results are better than those of the classical grey GM, DGM, and NDGM models as well as those of the grey-extended SIGM model. At the same time, according to the FSIGM model, this paper predicts China’s crude oil consumption for 2015–2020.
33
Milosan, Ioan, Gilles Flamant, Ionelia Voiculescu, Victor Geanta, Daniel Munteanu, Tibor Bedo, Mihai Alin Pop et al. „Comparative Study of Heat Treatment Effects Performed with Solar Energy and Electric Furnace on EN 1.4848 Stainless Steel Alloyed with Co, W, Cu and Mo“. Revista de Chimie 69, Nr. 5 (15.06.2018): 1050–54. http://dx.doi.org/10.37358/rc.18.5.6259.
Der volle Inhalt der QuelleAnnotation:
This paper presents a comparative study of the microstructure characteristics resulted from heat treatments performed with solar energy and with electric resistance furnace of EN 1.4848 steel alloyed with Co-W-Cu-Mo. In order to increase the hardness characteristics, mechanical strength and fatigue, this steel was previously alloyed with 6.15 wt% Co, 1.8 wt% W, 0.3 wt% Cu and 0.2 wt% Mo. The alloying with Co and W aimed at increasing the hardness, while Cu was added to improve the tensile strength and Mo to increase the fatigue strength. The thermal treatment of EN 1.4848 austenitic stainless steel alloyed with Co-W-Cu-Mo consisted in solid solution quenching in liquid, after heating the samples at 1050�C, maintaining the plateau temperature for about 10 min and subsequently cooling in water or oil. The purpose of this treatment was to dissolve the compounds possibly formed during the production of steel, if any, and to form supersaturated solid solutions, stable at low temperatures and in corrosive environments. The microstructural aspects, microhardness, and Differential Scanning Calorimetry (DSC) results were highlighted, in order to emphasize the solid phase transformations, on both heat treatment variants. The microstructure consists of high-alloy austenite, supersaturated with carbon, with small proportions of delta ferrite with interdendritic precipitations and various intermetallic compounds, very stable and without showing phase transformations up to negative temperatures (- 75 C). Comparing the solar quenched samples to the electric-quenched one, regarding to the differential scanning calorimetry (DSC) analysis, showed that independently of the applied cooling process (in water or oil) the phase transformation temperature is lower for the solar-quenched samples compared to the electric-quenched ones.
34
Zhang, Jun Hong, Zhen Peng He, Wen Peng Ma, Liang Ma und Gui Chang Zhang. „Coupled Bending-Torsional Vibration Analysis of Rotor System with Two Asymmetric Disks“. Applied Mechanics and Materials 130-134 (Oktober 2011): 2335–39. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.2335.
Der volle Inhalt der QuelleAnnotation:
The dynamic equations derived based on the actual rotor system with two asymmetric disks. In the analysis, the eccentric, rubbing fault characteristics and internal damping effects is considered, and all the analysis is established based on nonlinear oil film force model and coupled bending-torsional differential equations. The Rugge-Kutta method is used to solve numerical model, the torsional displacement response, torsion angle and Poincare map are obtained. The results show torsion amplitudes with initial phase difference π / 2 is larger than initial phase difference of π and 0. In order to eliminate the rigid rolling component the relative torsional angle must be considered.
35
PORTILLO-RUIZ, MARTHA CRISTINA, SABINA VIRAMONTES-RAMOS, LAILA NAYZZEL MUÑOZ-CASTELLANOS, MARÍA GUADALUPE GASTÉLUM-FRANCO und GUADALUPE VIRGINIA NEVÁREZ-MOORILLÓN. „Antifungal Activity of Mexican Oregano (Lippia berlandieri Shauer)“. Journal of Food Protection 68, Nr. 12 (01.12.2005): 2713–17. http://dx.doi.org/10.4315/0362-028x-68.12.2713.
Der volle Inhalt der QuelleAnnotation:
Antifungal and sensorial properties of spices have been recognized for years. The antifungal compounds are products of the plant's secondary metabolism, and the action of those compounds could be used to inhibit the growth of spoilage and pathogenic microorganisms in food. Mexican oregano (Lippia berlandieri) grows wildly in the desert zone of Mexico and is usually added to regional foods. The goal of this study was to evaluate the antifungal activity of Mexican oregano versus food-contaminant fungi. Fungi were isolated from spoiled fruit and vegetables and identified according to morphological characteristics. The antifungal activity of oregano was evaluated by radial growth measurement on potato dextrose agar added with dried oregano (0.25 to 4.0%). The essential oil antifungal activity of oregano was also evaluated by the diffusion well test. Twenty-one fungal strains were isolated, which included Penicillium, Geotrichum, Aspergillus, and Bipolaris. In seven of the 21 strains, no inhibitory effect was observed at either concentration of oregano. An increase in growth at the lower or higher concentrations of oregano, when compared to the control, was observed in two fungal strains; in 12 strains, a strong inhibitory effect of oregano was evident. The oregano essential oil was inhibitory to all fungal strains, but there were differences in the extent of the effect. Although the antifungal effect of oregano is strongly established, there was a differential effect with the fungal strains studied. Besides pathogenic fungi and bacteria, microbial spoilage flora should be considered when the addition of spices for food preservation is proposed.
36
Shagapov, V. Sh, und Z. M. Nagaeva. „On elastic regime of filtration in hydraulic fracture“. Proceedings of the Mavlyutov Institute of Mechanics 11, Nr. 2 (2016): 156–66. http://dx.doi.org/10.21662/uim2016.2.023.
Der volle Inhalt der QuelleAnnotation:
Fluid recovery from a well in the modes of constant pressure drop and constant flow rate is considered basing on a theoretical model of filtration in a hydraulic fracture. Exact analytical solutions are obtained that allowed analyzing the effect of the reservoir and fracture properties (such as porosity, permeability and crack width) as well as the rheological properties of the saturating fluid upon: pressure evolution in the fracture, well flow rate at constant pressure drop, and pressure evolution in the wellbore. On the basis of theoretical models describing the filtration for a crack in an oil or gas reservoirs, the considered problem on the selection of fluids from the well in modes constant differential pressure and constant flow. For the considered tasks are received exact analytical solutions, based on which we analyzed the influence of reservoir characteristics of the formation and fractures (for example, their porosity, permeability and width of cracks) and the rheological properties of the saturating fluid on the evolution of the pressure in the fracture, the production rate at a constant differential to the dynamics of the pressure in the well.
37
Masalmeh, Shehadeh K., Issa M. Abu-Shiekah und Xudong Jing. „Improved Characterization and Modeling of Capillary Transition Zones in Carbonate Reservoirs“. SPE Reservoir Evaluation & Engineering 10, Nr. 02 (01.04.2007): 191–204. http://dx.doi.org/10.2118/109094-pa.
Der volle Inhalt der QuelleAnnotation:
Summary An oil/water capillary transition zone often contains a sizable portion of a field's initial oil in place, especially for those carbonate reservoirs with low matrix permeability. The field-development plan and ultimate recovery may be influenced heavily by how much oil can be recovered from the transition zone. This in turn depends on a number of geological and petrophysical properties that influence the distribution of initial oil saturation (Sor) against depth, and on the rock and fluid interactions that control the residual oil saturation (Sor), capillary pressure, and relative permeability characteristics as a function of initial oil saturation. Because of the general lack of relevant experimental data and the insufficient physical understanding of the characteristics of the transition zone, modeling both the static and dynamic properties of carbonate fields with large transition zones remains an ongoing challenge. In this paper, we first review the transition-zone definition and the current limitations in modeling transition zones. We describe the methodology recently developed, based on extensive experimental measurements and numerical simulation, for modeling both static and dynamic properties in capillary transition zones. We then address how to calculate initial-oil-saturation distribution in the carbonate fields by reconciling log and core data and taking into account the effect of reservoir wettability and its impact on petrophysical interpretations. The effects of relative permeability and imbibition capillary pressure curves on oil recovery in heterogeneous reservoirs with large transition zones are assessed. It is shown that a proper description of relative permeability and capillary pressure curves including hysteresis, based on experimental special-core-analysis (SCAL) data, has a significant impact on the field-performance predictions, especially for heterogeneous reservoirs with transition zones. Introduction The reservoir interval from the oil/water contact (OWC) to a level at which water saturation reaches irreducible is referred to as the capillary transition zone. Fig. 1 illustrates a typical capillary transition zone in a homogeneous reservoir interval within which both the oil and water phases are mobile. The balance of capillary and buoyancy forces controls this so-called capillary transition zone during the primary-drainage process of oil migrating into an initially water-filled reservoir trap. Because the water-filled rock is originally water-wet, a certain threshold pressure must be reached before the capillary pressure in the largest pore can be overcome and the oil can start to enter the pore. Hence, the largest pore throat determines the minimum capillary rise above the free-water level (FWL). As shown schematically in Fig. 2, close to the OWC, the oil/water pressure differential (i.e., capillary pressure) is small; therefore, only the large pores can be filled with oil. As the distance above the OWC increases, an increasing proportion of smaller pores are entered by oil owing to the increasing capillary pressure with height above the FWL. The height of the transition zone and its saturation distribution is determined by the range and distribution of pore sizes within the rock, as well as the interfacial-force and density difference between the two immiscible fluids.
38
Cheng, Li, Chang Jinfeng, Liu Zhao, Fan Shangchun und Ding Tianhuai. „Characteristics Analysis of Joint Acoustic Echo and Noise Suppression in Periodic Drillstring Waveguide“. Shock and Vibration 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/741314.
Der volle Inhalt der QuelleAnnotation:
A new method of wireless data telemetry used by oil industry uses compressional acoustic waves to transmit downhole information from the bottom hole to the surface. Unfortunately, acoustic echoes and drilling vibration noises in periodic drillstring are a major issue in transmission performance. A combined acoustic echo and noise suppression method based on wave motion characteristic in drillstring is adopted to enhance an upward-going transmitted acoustic signal. The presented scheme consists of a primary acoustic echo canceller using an array of two accelerometers for dealing with the downward-going noises and a secondary acoustic insulation structure for restraining the upward-going vibration noises. Furthermore, the secondary acoustic insulation structure exhibits a banded and dispersive spectral structure because of periodic groove configuration. By using a finite-differential algorithm for the one-dimensional propagation of longitudinal waves, acoustic receiving characteristics of transmitted signals are simulated with additive Gaussian noise in a periodic pipe structure of limited length to investigate the effects on transmission performance optimization. The results reveal that the proposed scheme can achieve a much lower error bit ratio over a specified acoustic isolation frequency range with a 30–40 dB reduction in the average noise level compared to traditional single-receiver scheme.
39
Liu, Qi-guo, You-jie Xu, Long-xin Li und An-zhao Ji. „Rate Decline Behavior of Selectively Completed Horizontal Wells in Naturally Fractured Oil Reservoirs“. Mathematical Problems in Engineering 2019 (18.04.2019): 1–13. http://dx.doi.org/10.1155/2019/7281090.
Der volle Inhalt der QuelleAnnotation:
Selectively completed horizontal wells (SCHWs) can significantly reduce cost of completing wells and delay water breakthrough and prevent wellbore collapse in weak formations. Thus, SCHWs have been widely used in petroleum development industry. SCHWs can shorten the effective length of horizontal wells and thus have a vital effect on production. It is significant for SCHWs to study their rate decline and flux distribution in naturally fractured reservoirs. In this paper, by employing motion equation, state equation, and mass conservation equation, three-dimension seepage differential equation is established and corresponding analytical solution is obtained by Laplace transform and finite cosine Fourier transform. According to the relationship of constant production and wellbore pressure in Laplace domain, dimensionless rate solution is gotten under constant wellbore pressure in Laplace domain. Dimensionless pressure and pressure derivate curves and rate decline curves are drawn in log-log plot and seven flow regimes are identified by Stehfest numerical inversion. We compared the simplified results of this paper with the results calculated by Saphir for horizontal wells in naturally fractured reservoirs. The results showed excellent agreement. Some parameters, such as outer boundary radius, storativity ratio, cross-flow coefficient, number and length of open segments, can obviously affect the rate integral and rate integral derivative log-log curves of the SCHWs. The proposed model in this paper can help better understand the flow regime characteristics of the SCHWs and provide more accurate rate decline analysis of the SCHWs data to evaluate formation.
40
de Almeida Magalhães, Thalita Sévia Soares, Pollyana Cristina de Oliveira Macedo, Stephany Yumi Kawashima Pacheco, Sofia Santos da Silva, Euzébio Guimarães Barbosa, Rayanne Rocha Pereira, Roseane Maria Ribeiro Costa et al. „Development and Evaluation of Antimicrobial and Modulatory Activity of Inclusion Complex of Euterpe oleracea Mart Oil and β-Cyclodextrin or HP-β-Cyclodextrin“. International Journal of Molecular Sciences 21, Nr. 3 (31.01.2020): 942. http://dx.doi.org/10.3390/ijms21030942.
Der volle Inhalt der QuelleAnnotation:
The development of inclusion complexes is used to encapsulate nonpolar compounds and improve their physicochemical characteristics. This study aims to develop complexes made up of Euterpe oleracea Mart oil (EOO) and β-cyclodextrin (β-CD) or hydroxypropyl-β-cyclodextrin (HP-β-CD) by either kneading (KND) or slurry (SL). Complexes were analyzed by molecular modeling, Fourier-transform infrared spectroscopy, scanning electron microscopy, powder X-ray diffraction, thermogravimetry analysis and differential scanning calorimetry. The antibacterial activity was expressed as Minimum Inhibitory Concentration (MIC), and the antibiotic resistance modulatory activity as subinhibitory concentration (MIC/8) against Escherichia coli, Streptomyces aureus, Pseudomonas aeruginosa and Enterococcus faecalis. Inclusion complexes with β-CD and HP-β-CD were confirmed, and efficiency was proven by an interaction energy between oleic acid and β-CD of −41.28 ± 0.57 kJ/mol. MIC values revealed higher antibacterial activity of complexes compared to the isolated oil. The modulatory response of EOO and EOO-β-CD prepared by KND as well as of EOO-β-CD and EOO-HP-β-CD prepared by SL showed a synergistic effect with ampicillin against E. coli, whereas it was not significant with the other drugs tested, maintaining the biological response of antibiotics. The antimicrobial response exhibited by the complexes is of great significance because it subsidizes studies for the development of new pharmaceutical forms.
41
Liang, Feng, Xiao-Dong Yang, Wei Zhang und Ying-Jing Qian. „Nonlinear Free Vibration of Spinning Viscoelastic Pipes Conveying Fluid“. International Journal of Applied Mechanics 10, Nr. 07 (August 2018): 1850076. http://dx.doi.org/10.1142/s175882511850076x.
Der volle Inhalt der QuelleAnnotation:
Drill strings are one of the most significant rotor components employed in oil and gas exploitation. In this paper, an improved dynamical model of drill-string-like pipes conveying fluid is developed by taking into account the axial spin, fluid–structure interaction (FSI), damping as well as curvature and inertia nonlinearities. The partial differential equations of motion are derived by two sequential Euler angles and the Hamilton principle and then directly handled by the multiple scales method. The nonlinear amplitudes, frequencies and whirling mode shapes are all investigated towards various system parameters to display the nonlinear dynamical characteristics of such a special rotor system coupled with FSI. It is revealed that the nonlinear amplitudes and frequencies are explicitly dependent on the spinning speed, while the flowing fluid mainly contributes to the linear frequencies, and consequently influences the nonlinear amplitudes and frequencies. The FSI effect and axial spin can both improve the forward procession mode and suppress the backward one, while both procession modes will be suppressed by the viscoelastic damping. The pipe will ultimately present a forward as well as decayed whirling motion for the fundamental mode.
42
Liu, Fawang, Tahir Ali und Zhong Liu. „Comparative Transcriptomic Analysis Reveals the Effects of Drought on the Biosynthesis of Methyleugenol in Asarum sieboldii Miq.“ Biomolecules 11, Nr. 8 (18.08.2021): 1233. http://dx.doi.org/10.3390/biom11081233.
Der volle Inhalt der QuelleAnnotation:
Asarum sieboldii Miq., a perennial herb in the family Aristolochiaceae, is widely used to treat colds, fever, headache and toothache in China. However, little is known about the drought-tolerance characteristics of A. sieboldii. In this study, to elucidate the molecular–genetic mechanisms of drought-stress tolerance of A. sieboldii, RNA-seq was conducted. In total, 53,344 unigenes were assembled, and 28,715 unigenes were annotated. A total of 6444 differential-expression unigenes (DEGs) were found, which were mainly enriched in phenylpropanoid, starch and sucrose metabolic pathways. Drought stress revealed significant up-regulation of the unigenes encoding PAL, C4H, HCT, C3H, CCR and IGS in the methyleugenol-biosynthesis pathway. Under the condition of maintaining drought for 15 days and 30 days, drought stress reduced the biosynthesis of volatile oil by 24% and 38%, respectively, while the production of key medicinal ingredients (such as methyl eugenol) was increased. These results provide valuable information about the diverse mechanisms of drought resistance in the A. sieboldii, and the changes in the expression of the genes involved in methyleugenol biosynthesis in response to drought stress.
43
Kong, Lingfei, Han Niu, Xiaoli Hou und Qingfeng Wang. „Whirling vibration of drilling shaft in minimal quantity lubrication deep hole drilling using theoretical and experimental investigation“. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 229, Nr. 13 (18.11.2014): 2433–42. http://dx.doi.org/10.1177/0954406214559110.
Der volle Inhalt der QuelleAnnotation:
Under the concept of safety, improving efficiency, or reducing costs in deep hole drilling, the effect of minimal quantity lubrication (MQL) on the dynamic characteristics of drilling shaft is analyzed. A model is presented to describe the pressure function of MQL cutting fluid during drilling process. This model is based on the compressible Reynolds equation in air/oil feature with nonlinearity, and the differential transformation theory is introduced to solve the time-dependent pressure equation satisfied with MQL cutting fluid. Further, with an emphasis on model development, experiments are performed to validate the correctness and effectiveness of the above methods. A series of experimental investigations are carried out on the whirling characteristics of drilling shaft when the rotational speed and drilling depth are changed. Additionally, the vibration trajectories of drilling shaft and the surface roughness of hole are detected under different experimental conditions such as MQL drilling or traditional drilling. The results show that the whirling trajectory of drilling shaft decreases significantly in MQL deep hole drilling but the surface roughness of machined hole is worse due to surface scratches or scales. Nevertheless, there exists an optimal rotational speed of drilling shaft to improve machining precision of hole surface. These results indicate that the MQL method has shown potential to be even more productive as compared to traditional drilling and that the proposed method in this paper can lay a foundation for investigating the dynamic stability of drilling shaft in MQL drilling.
44
Calver, Teri, Marty Yarmuch, Alexandra J. Conway und Katherine Stewart. „Strong legacy effect of peat composition on physicochemical properties of reclamation coversoil“. Canadian Journal of Soil Science 99, Nr. 3 (01.09.2019): 244–53. http://dx.doi.org/10.1139/cjss-2018-0160.
Der volle Inhalt der QuelleAnnotation:
Incorporation of salvaged peat in soil cover designs for oil sands mine reclamation is a common practice. However, current peat salvage practices do not differentiate between peatland types or the botanical composition of peat. In this study, we characterized the botanical composition of natural peat and coversoil on reclaimed sites and examined the influence of botanical composition on the physicochemical characteristics of reclaimed coversoil. Peat samples were collected from 15 natural peatlands (bog, poor fen, and rich fen) and peat coversoils were sampled from six reclaimed sites in the Athabasca oils sands region. The botanical compositions (Sphagnum, wood Sphagnum, woody, and woody/moss herbaceous) of all samples were determined. We found that natural peatland types had different physicochemical properties, primarily driven by Sphagnum-dominated samples with a high carbon:nitrogen (C:N) ratio and low total exchange capacity (TEC) when compared with samples dominated by more woody/moss herbaceous material. Similarly, we found that coversoil with Sphagnum-dominated peat compared with woody/moss herbaceous peat had lower TEC, pH, and total nitrogen values and higher C:N ratios (∼40 vs. 20 for Sphagnum and woody/moss herbaceous, respectively). Our results indicate that physicochemical properties driven by botanical composition remain in coversoil 5 yr after placement.
45
Moolsin, Supat, Nattawud Saksayamkul und Adul Na Wichien. „Natural rubber grafted poly(methyl methacrylate) as compatibilizer in 50/50 natural rubber/nitrile rubber blend“. Journal of Elastomers & Plastics 49, Nr. 5 (07.10.2016): 422–39. http://dx.doi.org/10.1177/0095244316671021.
Der volle Inhalt der QuelleAnnotation:
The effects of graft copolymers applied as compatibilizers for natural rubber/nitrile rubber (NR/NBR) blends at 50/50 (w/w) on cure characteristics, mechanical properties, thermal properties, oil resistance, and morphology were investigated. The graft copolymers of methyl methacrylate (MMA) onto NR initiated by benzoyl peroxide (NR- g-PMMA<BPO>) and by potassium persulfate (NR- g-PMMA<PPS>) under emulsion polymerization were synthesized and used to compatibilize the blends. The structures of the copolymers were characterized by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. NR was blended with NBR via a two-roll mill at 70°C under the compatibilizer loading ranging from 0 to 10 parts per hundred of rubber (phr). The results showed that the tensile property and tear strength of the blends increased with the increasing amount of NR- g-PMMA<BPO> as a compatibilizer. Thermal aging determined in terms of tensile properties exhibited the smaller difference between before and after aging in an oven with the increasing compatibilizer loading. The morphology of the compatibilized NR/NBR vulcanizates was investigated by scanning electron microscopy of the tensile fracture surfaces, which exhibited the improvement of interfacial adhesion between the two rubber phases. The thermal properties of compatibilized NR/NBR vulcanizates were reported in terms of a glass transition temperature under differential scanning calorimetry and dynamic mechanical analysis. The incorporation of an appropriate amount of the compatibilizer into the blends apparently improved the oil resistance of NR. Among them, the blend filled with 7.5 phr of NR- g-PMMA<BPO> showed the lowest volume change in IRM 903 oil.
46
Zhang, Jinya, Yongjiang Li, K. Vafai und Yongxue Zhang. „An investigation of the flow characteristics of multistage multiphase pumps“. International Journal of Numerical Methods for Heat & Fluid Flow 28, Nr. 3 (05.03.2018): 763–84. http://dx.doi.org/10.1108/hff-06-2017-0252.
Der volle Inhalt der QuelleAnnotation:
Purpose Numerical simulations of a multistage multiphase pump at different operating conditions were performed to study the variational characteristics of flow parameters for each impeller. The simulation results were verified against the experimented results. Because of the compressibility of the gas, inlet volume flow rate qi and inlet flow angle ßi for each impeller decrease gradually from the first to the last stage. The volume flow rate at the entrance of the pump q, rotational speed n and inlet gas volume fraction (IGVF) affect the characteristics of qi and ßi. Design/methodology/approach The hydraulic design features of the impellers in the multistage multiphase pump are obtained based on the flow parameter characteristics of the pump. Using the hydraulic setup features, stage-by-stage design of the multistage multiphase pump for a nominal IGVF has been conducted. Findings The numerical simulation results show that hydraulic loss in impellers of the optimized pump is substantially reduced. Furthermore, the hydraulic efficiency of the optimized pump increases by 3.29 per cent, which verifies the validation of the method of stage-by-stage design. Practical implications Under various operating conditions, qi and ßi decrease gradually from the first to the fifth stage because of the compressibility of the gas. For this characteristic, the fluid behavior varies at each stage of the pump. As such, it is necessary to design impellers stage by stage in a multistage rotodynamic multiphase pump. Social implications These results will have substantial effect on various practical operations in the industry. For example, in the development of subsea oilfields, the conventional conveying equipment, which contains liquid-phase pumps, compressors and separators, is replaced by multiphase pumps. Multiphase pumps directly transport the mixture of oil, gas and water from subsea oilwells through a single pipeline, which can simplify equipment usage, decrease backpressure of the wellhead and save capital costs. Originality/value Characteristics of a multistage multiphase pump under different operating conditions were investigated along with features of the inlet flow parameters for every impeller at each compression stage. Our simulation results have established that the change in the inlet flow parameters of every impeller is mainly because of the compressibility of the gas. The operational parameters q, n and IGVF all affect the characteristics of qi and ßi. However, the IGVF has the most prominent effect. Lower values of IGVF have an insignificant effect on the gas compressibility. Higher values of IGVF have a significant effect on the gas compressibility. All these characteristics affect the hydraulic design of the impellers for a multistage multiphase pump. In addition, the machining precision should also be considered. Considering all these factors, when IGVF is lower than 10 per cent, all the impellers in the pump can be designed uniformly. When IGVF varies from 10 to 30 per cent, the first two stages should be designed separately, and the latter stages are uniform starting with the second stage. When IGVF varies from 30 to 50 per cent, the first three stages should be designed separately, and the latter stages are going to be similar to the third stage. An additional increase in IGVF results in degeneration of the differential pressure of the pump, which will reduce the compressibility of the gas. As such, it can be deduced that only the first three stages should be designed separately, and the latter stages will be similar to the third stage. In addition, for the pump working under a lower volume flow rate than 25 m3/h, the first three stages should be designed individually while keeping the geometrical structure of the subsequent stages the same as the third stage.
47
Vladimir, Sokolov, Igor` Razov und Andrey Dmitriev. „Influence of the length parameter of an underground oil pipeline on the frequency of free oscillation“. E3S Web of Conferences 164 (2020): 03024. http://dx.doi.org/10.1051/e3sconf/202016403024.
Der volle Inhalt der QuelleAnnotation:
The problem of finding the natural frequencies of thin-walled underground oil pipelines is solved, based on the application of a semi-momentless theory of cylindrical shells of medium bending, in which bending moments in the longitudinal direction are not taken into account in view of their smallness compared with moments acting in the transverse direction. The solution to this approach is a fourth-order homogeneous differential equation satisfying the boundary conditions of articulation at each end. This equation includes the parameters of the length, internal pressure, thinness of the pipeline, as well as the values of the coefficient of elastic resistance of the soil, the attached mass of the soil and the attached mass of the flowing oil. Based on the data obtained by the derived formulas, the frequency characteristics of large-diameter thin-walled underground oil pipelines are determined depending on the length of the element, as well as on the soil conditions. It has been established that the minimum frequencies are realized for shell modes of vibration with a length parameter of the pipeline section (the ratio of the length of the section to the radius) not exceeding 13. A formula is derived that allows one to determine the boundary between the use of the rod and shell theory for calculating pipelines for dynamic effects. Using the dynamic stability criterion, in which the frequency of natural oscillations vanishes, expressions are derived that allow one to determine the external critical pressure on the wall of the pipeline, which takes into account the length of the pipeline, as well as the number of half waves in the transverse and longitudinal directions, in which the pipeline goes into emergency condition.
48
Zheng, Nan, Jie Liu und Wenge Li. „TO/TMMP-TMTGE Double-Healing Composite Containing a Transesterification Reversible Matrix and Tung Oil-Loaded Microcapsules for Active Self-Healing“. Polymers 11, Nr. 7 (02.07.2019): 1127. http://dx.doi.org/10.3390/polym11071127.
Der volle Inhalt der QuelleAnnotation:
Thermoset epoxies are widely used due to their excellent properties, but conventional epoxies require a complicated and time-consuming curing process, and they cannot self-healed, which limits their applications in self-healing materials. Extrinsic and intrinsic self-healing materials are applied in various fields due to their respective characteristics, but there is a lack of comparison between the two types of healing systems. Based on this, a thiol-epoxide click reaction catalyzed by an organic base was introduced to achieve the efficient preparation of thiol-epoxy. Furthermore, tung oil (TO)-loaded microcapsules were introduced into the thiol-epoxy matrix of dynamic transesterification to obtain a TO/TMMP-TMTGE self-healing composite with an intrinsic–extrinsic double-healing system. For comparison, a TMMP-TMTGE self-healing material with an intrinsic healing system was also prepared, which contained only thiol and epoxy curing chemistries. The effect of the core/shell ratio on the morphology, average particle size, and core content of TO-loaded microcapsules was studied. It was found that when the core/shell ratio was 3:1, the average particle size of the microcapsules was about 99.8 μm, and the microcapsules showed good monodispersity, as well as a core content of about 58.91%. The differential scanning calorimetry (DSC) results showed that the TO core was successfully encapsulated and remained effective after encapsulation. Furthermore, scanning electron microscopy (SEM), atomic force microscopy (AFM), tensile tests, and electrochemical tests were carried out for the two types of self-healing materials. The results showed that the TO/TMMP-TMTGE composite and TMMP-TMTGE material both had self-healing properties. In addition, the TO/TMMP-TMTGE composite was superior to the TMMP-TMTGE material due to its better self-healing performance, mechanical strength, and corrosion protection performance.
49
Bhattacharya, S., J. D. Belgrave, D. G. Mallory, R. G. Moore, M. G. Ursenbach und S. A. Mehta. „Investigation of Thermal Fingerprint in Accelerating-Rate Calorimetry for Air-Injection Enhanced-Oil-Recovery Processes“. SPE Journal 22, Nr. 02 (10.10.2016): 548–61. http://dx.doi.org/10.2118/178095-pa.
Der volle Inhalt der QuelleAnnotation:
Summary The accelerating-rate calorimeter (ARC) is unique for its exceptional adiabaticity, its sensitivity, and its sample universality. Accelerating Rate Calorimetry is one of the screening tests used to determine the suitability for air-injection enhanced oil recovery (EOR). These tests show oil reactivity and exothermicity over a broad range of temperatures: low-temperature range (LTR), negative-temperature-gradient region (NTGR), and high-temperature range (HTR). An experimental and simulation study was carried out to expand understanding and interpretation of the data derived from high-pressure closed-ARC tests. Athabasca bitumen was used for the experimental study in a closed ARC at 13.89 MPag (2000 psig) to identify the temperature ranges over which the oil reacts with oxygen in the injected air. Self-heat rate from accelerating-rate calorimetry and mass-loss rates from the differential thermogravimetric analysis show the influence of mass transfer of oxygen within bitumen in the LTR and HTR. A numerical model was developed to integrate the concept of mass transfer with a reaction-kinetic model. The model incorporates solubility of oxygen with partition equilibrium coefficient (K-value) as a medium to introduce oxygen into the bitumen layer, which later transfers throughout oil layer by diffusion. This model considers both low- and high-temperature oxidation (LTO and HTO), and thermal-cracking reactions, as described in traditional reaction-kinetic models of in-situ-combustion (ISC) processes. Results show that formation of an asphaltenes film in the LTR caused by oxidation of maltenes obstructs oxygen (mass-transfer restriction) penetration into the bitumen layer. The simulated result shows that, by integrating mass transfer with the kinetic model, it is possible to predict the NTGR. Viscosity and temperature dependence on the mass transfer of oxygen is linear. As time passes and chemical reaction becomes more important with increasing temperature, the relationship deviates from linearity. With increasing temperature, the influence of chemical interaction on the oxygen distribution becomes greater, and this results in a shorter initial stage of mass transfer of oxygen within the bitumen film at low temperatures. This implies that the ARC can be a useful tool for understanding the effect of mass transfer on the oxidation characteristic for predicting LTR, NTGR, and HTR.
50
Leroy, Jef L., Deanna K. Olney, Noé Nduwabike und Marie T. Ruel. „Tubaramure, a Food-Assisted Integrated Health and Nutrition Program, Reduces Child Wasting in Burundi: A Cluster-Randomized Controlled Intervention Trial“. Journal of Nutrition 151, Nr. 1 (26.11.2020): 197–205. http://dx.doi.org/10.1093/jn/nxaa330.
Der volle Inhalt der QuelleAnnotation:
ABSTRACT Background Little is known about the impact of food-assisted maternal and child health programs (FA-MCHN) on child wasting. Objectives We assessed the impact of Tubaramure, a FA-MCHN program in Burundi, on child (0 to 24 months) wasting and the differential impacts by socio-economic characteristics and age. The program targeted women and their children during the first 1000 days and included 1) food rations, 2) strengthening and promotion of use of health services, and 3) behavior change communication (BCC). Methods We conducted a 4-arm, cluster-randomized, controlled trial (2010–2012). Clusters were defined as “collines” (communities). Impact was estimated using repeated cross-sectional data (n = ∼2620 children in each round). Treatment arms received household and individual (mother or child in the first 1000 days) food rations (corn-soy blend and micronutrient-fortified vegetable oil) from pregnancy to 24 months (T24 arm), from pregnancy to 18 months (T18), or from birth to 24 months (TNFP). All beneficiaries received the same BCC for the first 1000 days. The control arm received no rations or BCC. Results Wasting (weight-for-length Z-score <2 SD) increased from baseline to follow-up in the control group (from 6.5% to 8%), but Tubaramure had a significant (P < 0.05) protective effect on wasting [treatment arms combined, −3.3 percentage points (pp); T18, −4.5 pp] and on the weight-for-length z-score (treatment arms combined, +0.15; T24, +0.20; T18, +0.17). The effects were limited to children whose mother and household head had no education, and who lived in the poorest households. The largest effect was found in children 6 to 12 months of age: the group with the highest wasting prevalence. Conclusions FA-MCHN programs in highly food-insecure regions can protect the most disadvantaged children from wasting. These findings are particularly relevant in the context of the economic crisis due to the coronavirus disease 2019 pandemic, which is expected to dramatically increase child wasting.