首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 234 毫秒
1.
The existence of nanographene in cluster form is discussed in organic solvents. Theories are developed based on the columnlet, bundlet and droplet models describing the size-distribution functions. Phenomena present a unified explanation in the columnlet model in which free energy of Cgraphene involved in cluster is combined from a volume part proportional to the number of molecules n in cluster and a constant. The columnlet model enables describing distribution function of Cgraphene clusters by size. From purely geometrical considerations the columnlet (Cgraphene), bundlet (single-wall carbon nanotube), CNT (carbon nanotube), SWNT (single-wall C-nanotube), and carbon nanobud, CNB (carbon nanobud)) and droplet (fullerene) models predict dissimilar behaviours. The interaction-energy parameters of Cgraphene are taken from C60. An CNB behaviour or further is expected. The decay of solubility with rising temperature is smaller for Cgraphene than for SWNT and CNB and, furthermore, than for C60, in agreement with lesser numbers of units in Cgraphene clusters. The discrepancy between the experimental data of the heat of solution of fullerenes, CNTs, CNBs and graphenes is ascribed to the sharp concentration dependence of the heat of solution. The diffusion coefficient drops with temperature result greater for Cgraphene than CNB and SWNT than C60 corresponding to lesser number of units in clusters. The aggregates near (C60)13, SWNT/CNB7 and (Cgraphene)3 could be representative of the droplet, bundlet and columnlet models.  相似文献   

2.
Morelos is the fourth in area cultivated and production volume of avocado. Of the 13 municipalities where it is farmed, Ocuituco represents 43.51% and Tetela del Volain 27.53%. Despite being one of the main fruit species in Morelos, no information related to the fertility of the soil where it is grown, the quality of water available for irrigation and nutritional status of this important fruit for the state. The study was conducted in the municipality of Ocuituco which identified three agro-habitats taking into account climate, landform, soil type and altitude. In each agro-habitat were carried out soil sampling to determine the physical and chemical characteristics based on the Mexican Official Standard NOM-021-SEMARNAT-2000, the chemical quality of water for irrigation as described by Richards (1954) and crop nutrient status of avocado "Hass" according to the methodology described by Maldonado (2002). The soils had different physical and chemical characteristics, as well as the nutritional status of avocado trees in the three agro-habitats. The trees had excessive concentration of CI, Cu and Zn. Indices of optimal percentage deviation expressed different nutritional requirements. The water used for irrigation was of low salinity and sodium content, so it can be used without restrictions.  相似文献   

3.
LWD(logging while drilling) data has been used to explore complex subtle reservoirs by realtime visual interpretation and geo-steering.The method comprises of computer communication,well log data processing,formation recognition,reservoir modeling and model updating in real time.We studied the key technologies related to real-time LWD data visual interpretation and geo-steering and developed computer software with Chinese intellectual property rights covering the following important aspects: 1) real-time computer communication of well site LWD data;2) visualization of geological model and borehole information;3) real-time interpretation of LWD data;4) real-time geological model updating and geo-steering technology.We use field application examples to demonstrate the feasibility and validity of the proposed technologies.  相似文献   

4.
The reservoir volumetric approach represents a widely accepted, but flawed method of petroleum play resource calculation. In this paper, we propose a combination of techniques that can improve the applicability and quality of the resource estimation. These techniques include: 1) the use of the Multivariate Discovery Process model (MDP) to derive unbiased distribution parameters of reservoir volumetric variables and to reveal correlations among the variables; 2) the use of the Geo-anchored method to estimate simultaneously the number of oil and gas pools in the same play; and 3) the crossvalidation of assessment results from different methods. These techniques are illustrated by using an example of crude oil and natural gas resource assessment of the Sverdrup Basin, Canadian Archipelago. The example shows that when direct volumetric measurements of the untested prospects are not available, the MDP model can help derive unbiased estimates of the distribution parameters by using information from the discovered oil and gas accumulations. It also shows that an estimation of the number of oil and gas accumulations and associated size ranges from a discovery process model can provide an alternative and efficient approach when inadequate geological data hinder the estimation. Cross-examination of assessment results derived using different methods allows one to focus on and analyze the causes for the major differences, thus providing a more reliable assessment outcome.  相似文献   

5.
Phosphorus is known to poison the exhaust gas catalysts used to control emissions in modem gasoline - fueled passenger car vehicles. Phosphorus volatility has been studied by others as a potential issue related to the compatibility of modem engine oils with exhaust gas catalysts using a modified version of the ASTM D5800 (Noack) test as well as the Sequence lllG engine test (ASTM D7320). The level of phosphorus volatility in these tests has been shown to be strongly affected by the chemistry of the zinc dialkyldithiophosphate (ZDDP) used in the engine oil for- mulation. The TEOST MHT - 4 test (ASTM D7097) is a high temperature deposit test currently included in the IL- SAC GF - 4 specification. This bench test simulates the oxidation and deposit - forming characteristics of engine oils in the hot zones of modem high - performance engines and, therefore, was chosen by the author(s) as a tool to investigate differences in phosphorus volatility of modem engine oils. Our investigations demonstrate that the TEOST MHT - 4 test is capable of measuring phosphorus volatility of engine oils with very good discrimination and preci- sion; it may be considered for use in future ILSAC standards (e.g. GF- 5).  相似文献   

6.
Edible insects, escamoles ant eggs of the Formicidae family are consumed by cultural tradition at rural communities and by sensory characteristics at high class restaurants of Mexico; however, people ignore the importance of insect consumption in the nutrition of humans. Laboratory spectroscopy methods in food analysis represent benefits in time and precision. The aim of this study is to assess macronutrients and micronutrients of escamoles and eggs by spectroscopic methods to inform population the benefits they provide in health and to mention the advantage in the use of these techniques at laboratory work. Samples were gather the second week of March and April 2012, at Hidalgo State and analyze moisture and macronutrients by AOAC (Association of Official Analytical Chemistry) methods, amino acids by cation exchange chromatography, tryptophan was determined by a colorimeter method, fatty acids by GC (gas chromatography) using helium as a carrier (AOAC), fat soluble vitamins A, D and E by HPLC (high performance liquid chromatography), and minerals by atomic absorption spectrophotometers and phosphorus by colorimeter (AOAC). Data showed high amount in proteins, lipids and minerals; low in fiber and soluble carbohydrates; contained all essential amino acids. Fatty acids contain monounsaturated and polyunsaturated. Fat soluble vitamins A, D and E. Minerals: sodium, phosphorus, potassium, magnesium, calcium and manganese. Escamoles ant eggs include polyunsaturated fatty acids essential for mental development, vitamin A to prevent eye diseases, vitamin E as antioxidant and vitamin D involved in calcium absorption that low intake, impair grow and bone health. Iron and zinc contained anemia. Regarding the laboratory benefits, needs less expensive chemicals, testing is clean, rapid and easy results of multiple samples, but it is required to handle by qualified chemists. In conclusion, data may change according to biotic and abiotic conditions of the environment; however, escamoles have all nutrients in adequate balance to improve human health; and provide faster and precise results.  相似文献   

7.
We analyze the excess area and depth to detachment method developed by Epard and Groshong (1993), and apply it to the sand box model of Ge et al (2004) to illustrate that inadequate consideration will affect the calculation of true depth to detachment. Using the data of Yu et al (2006) to fit linear regression lines, we obtain the depths to detachment of Kela-2, Misikantage anticline and Dongqiu-8 structures, 115.74km, 14.17km, and 75.48km below the reference level (Cretaceous bottom) respectively with the excess area intercept equal to zero. However, the calculation results of depth to detachment in Yu et al (2006) are based on excess area intercept unequal to zero.  相似文献   

8.
Effects of nitrogen-contained biodegradation enhancers: methyl diethanolamine oleate (MDEAO) and oleic diethanolamide (ODEA) on the adsorption behavior of n-hexadecane in soil were studied by laboratory batch experiments. The effect of two biodegradation enhancers on the partition coefficient (Kd values) and normalized to organic matter (Koc values) were determined. The adsorption isotherm curve of n-hexadecane in soil-water system were plotted. The measured results demonstrated that Koc values changed in the soil-water system with different enhancers but are relatively invariant for the same site soil. The Kd values rose with the increase of the organic matter content in different soil. The average values of Koc in soil-water system with MDEAO, ODEA and blank soil were 0.412, 0.252 and 0.309, respectively. The critical micelle concentration of ODEA and MDEAO were 0.7 mg/L and 1.9 mg/L, respectively, which means the solubilization capacity of ODEA is much stronger than MDEAO in soil-water system. Consequently, adsorption of MDEAO onto the solid surface increases the organic matter content in soil and makes it more effective in enhancing n-hexadecane adsorption. Oppositely, ODEA inhibits the adsorption of n-hexadecane due to less adsorption onto the soil particle surface and higher concentration in the soil-water system. According to the correlation coefficients, it was found that both Henry linear and Freundlich nonlinear isotherm sorption models were fitted to the data very well but the Freundlich model was better.  相似文献   

9.
Associating fluids containing water and alkanols show a strong non-ideal behaviour on thermodynamic properties Simple cubic equations of state (EOS). such as the Peng-Robinson (PR) equation, with conventional mixing rules are popular lbr its simplicity and eas3' implementation. However it is incapable of reliably representing the phase behaviour of associating mixtures. An effort has been made in this study to develop a new model in which the non-densit3'-dependent mixing rules are applied to the PR EOS to represent the phase behaviour of associating fluids. The proposed model takes into account of the polarity in the attractive term of the EOS by including both the conventional random mixing term and the asymmetric interaction term. The proposed model has been successfully applied to the calculation of the vapor-liquid equilibrium (VLE) and liquid-liquid equilibrium (LLE) of fluids containing water, alkanols, acid gases, and hydrocarbons. A satisfactory agreement between the predictions of the proposed model and the experimental data in the literature is reached.  相似文献   

10.
11.
Delayed coking is an important process used to convert heave oils to light products. Energy consumption and fight oil yield are important factors for evaluating the delayed coking process. This paper analyzes the energy consumption and product yields of delayed coking units in China. The average energy consumption shows a decreasing trend in recent years. The energy consumption of different refineries varies greatly, with the average value of the highest energy consumption approximately twice that of the lowest energy consumption. The factors affecting both energy consumption and product yields were analyzed, and correlation models of energy consumption and product yields were established using a quadratic polynomial. The model coefficients were calculated through least square regression of collected industrial data of delayed coking units. Both models showed good calculation accuracy. The average absolute error of the energy consumption model was approximately 85 MJ/t, and that of the product yield model ranged from 1 wt% to 2.3 wt%. The model prediction showed that a large annual processing capacity and high load rate will result in a reduction in energy consumption.  相似文献   

12.
The equilibrium constant (K0), change in free energy (△G), enthalpy (△H) and entropy (△S) of ammonium adsorption by a Cuban natural zeolite were estimated at the temperatures of 25, 35, 45 and 55℃ using extensively used approaches. Equilibrium data were obtained in the concentration range 50-1,200 mg·L-1 of ammonium and used in the estimation of thermodynamic parameters. Freundlich's isotherm model was found as with the best adjustment to equilibrium data at 25, 45 and 55℃, whereas, Redlich-Peterson's model had a better performance at 35 ℃. A discontinuous and unusual behavior was observed on adsorption capacity of the zeolite, with an increase from 25 ℃ to 35 ℃ followed by a decrease from 35℃ to 55 ℃. K0 values presented differences that reached up to 105 from one methodology to other. Depending on the method considered, AS results indicated both increase or decrease in system degree of disorder and △G indicated both physisorption or chemisorption process, proving the poor correlation between the estimation proceedings of such important data. The results from Gaines and Thomas method were recognized as the most correlated to calorimetric studies, as well as to equilibrium data and observations related to system entropy.  相似文献   

13.
Highly efficient synthesis methods have been developed and characteristics of nanometallocarbosilanes molecular structure were studied by the research team of GNIIChTEOS (State Research Institute for Chemistry and Technology of Organoelement Compounds). Nanometallocarbosilanes were synthesized by thermal co-condensation of oligocarbosilanes and alkyl amides of refractory metals. Initial, intermediate and final products of side reactions were characterized by 1H, 13C, 29Si NMR (nuclear magnetic resonance), IR (infra-red) spectroscopy, GPC (gel-penetrating chromatography), TGA (thermal gravimetric analysis), TEM (transmission electron microscopy), SEM (scanning electron microscopy), RES (X-ray phase analysis) and elemental analysis. The proposed synthesis method of nanometallocarbosilanes was lbund to produce fusable soluble organosilicon oligomers with homogeneous distribution of nanoscale (10-20 nm) metal particles in the oligomer matrix. A computational model of the group and elemental composition of nanometallocarbosilanes was developed; it was shown that they are molecular globules of near-spherical shape and rigid polycyclic structure. Thermochemical treatment of nanometallocarbosilanes leads to SiC-nanoceramics (a high yield of up to 75-80 mass%) modified by metal nanoparticles (20-30 nm) contributing to its stabilization. The application of preceramic oxygen-free nanometallocarbosilanes will make it possible to advance in solving the problem of ceramic composite materials with long-term resistance at temperatures above 1,500 ℃ in oxidizing environments.  相似文献   

14.
Acquisition footprint is a new concept to describe the seismic noise in three-dimensional seismic exploration and it is closely related to geometry and observation shuttering. At present, the study on acquisition footprints has become a hot spot. In partnership with the Dagang Oilfield, we used the channel sand body seismic physical model to study the characteristics of wide/narrow azimuth acquisition footprints and analyzed and compared the two types of footprints and their effects on target imaging. In addition, the footprints caused by data processing of the normal moveout offset (NMO) stretching aberration were discussed. These footprints are located only in the shallow or middle layer in the time slice, and possibly affect the imaging of shallow target layers, and have no influence on deep target imaging. Seismic physical modeling has its advantages in the study of acquisition footprints.  相似文献   

15.
The engine oil specifications of ILSAC GF - 4 ( implemented 2004 ) and GF - 5 ( expected 2010 ) have in common three important OEM needs: (1) improved fuel economy and its retention, (2) emissions system compatibility (related to phosphorus and sulfur content), and (3) improved oil robustness for extended oil life capability (e. g., reduced high temperature deposits and engine sludge, improved oxidative stability, and better valve train wear protec- tion). For emission systems compatibility, there is a trend towards lower phosphorus and sulfur content in engine oils while maintaining high anti - oxidation and anti - wear performances. In this paper, the friction - reducing, antiwear and antioxidant properties of a sulfurfree and phosphorusfree molybdate ester compound as lubricant additive are discussed. The investigation showed that the molybdate ester enables good frictionreducing ability of the lubricant, and maintains low friction coefficients even after period of severe oil oxidation, which indicates the potential for excellent fuel economy retention in passenger car vehicles. For other organomolybdenum additives, the investigation showed their frictionreducing ability decreased greatly after oxidation of the oil, although the performance appeared to be very good with the fresh oil before aging. In addition, the molybdate ester demonstrated a synergistic effect in anti - wear protection with zinc dialkyl dithiophosphate (ZDDP), a well- known commonly used additive in engine oils; this suggests that excellent wear protection is possible for an engine oil with reduced sulfur and phosphorus content. Moreover, the molybdate ester is also a strong synergist with arylamine antioxidants, which can retard its depletion in oxidized oil, extend its oxidative induction time, and reduce its high temperature deposit - forming tendency. Thus, this type of sulfur - free and phosphorus - free organo- molybdenum lubricant additive truly provides multifunctional performances, reducing friction, wear, and oxidation of an engine oil when combined with other suitable additives. Due to its phosphorus - free, sulfur- free and multifunctional properties, the molybdate ester compound can be extremely useful in formulat- ing modem engine oils with low phosphorus and sulfur content.  相似文献   

16.
The current applicable release & dispersion models are reviewed. A typical model is developed on the basis of LPG storage conditions in China and the authors' research. The study is focused on the relationship between LPG composition and release rate, and on the influence of buildings or structures located in the surrounding area on the dispersion of gas plume. The established model is compared with existing models by the use of published field test data.  相似文献   

17.
The finite volume method has been successfully applied in several engineering fields and has shown outstanding performance in fluid dynamics simulation. In this paper, the general framework for the simulation of near-wellbore systems using the finite volume method is described. The mathematical model and the numerical model developed by the authors are presented and discussed. A radial geometry in the vertical plane was implemented so as to thoroughly describe near-wellbore phenomena. The model was then used to simulate injection tests in an oil reservoir through a horizontal well and proved very powerful to correctly reproduce the transient pressure behavior. The reason for this is the robustness of the method, which is independent of the gridding options because the discretization is performed in the physical space. The model is able to describe the phenomena taking place in the reservoir even in complex situations, i.e. in the presence of heterogeneities and permeability barriers, demonstrating the flexibility of the finite volume method when simulating non-conventional tests. The results are presented in comparison with those obtained with the finite difference numerical approach and with analytical methods, if possible.  相似文献   

18.
Currently the catalytic reforming units are playing an increasingly important role for gasoline quality upgrading, increased production of high add-value aromatic compounds and supply of cheap hydrogen resources. The high proportion of FCC gasoline in China's automotive gasoline pool has led to a quite significant gap in gasoline quality as compared to the demand of World Fuel Charter and even to the new Chinese standards for unleaded automotive gasoline. According to the statistical data, the ratio of FCC naphtha in the gasoline pool is 35% in the US and 27% in EU, whereas that number is 75% in China's gasoline pool. The share of reformate and other high-quality gasoline components in the gasoline pool is 65% in the US and 73% in EU, whereas that number is merely 14% in China's gasoline pool along with a definite share of low-octane (straight-run) gasoline.  相似文献   

19.
Heavy oil upgrading is one of the mostimportanttopics in refining.Although there are a number ofnew heavy oil conversion processes available to the refiner,in today s economic climate,the mostimpor-tantfactor considered in choosing the right technology for heavy oil upgrading is to maximize the use ofthe existing processing units to minimize the investment cost.By making best use of the low value by-product and properly combining and renovating existing units,several heavy oil upgrading proces…  相似文献   

20.
According to the process features and the reaction mechanism of FDFCC technology, its two reaction subsystems, one for heavy oil riser reactor, the other for gasoline riser reactor, were respectively studied. Correspondingly, a 12-lump kinetic model for heavy oil FCC and a 9-lump kinetic model for gasoline catalytic upgrading were presented. Based on this work, mathematical correlation of the lumps in the feeds and products involved in the reaction subsystems and those of the overall reaction system were analyzed in detail. Then, a combined kinetic model for FDFCC, which was based on the data recovered from a commercial unit, was put forward. The reaction performance embodied by the kinetic constants for the combined model of FDFCC was in accordance with catalytic cracking reaction mechanism. The model-calculated values were close to the data obtained in commercial scale. The model was easy to be applied in practice and could also provide some theoretical groundwork for further research on kinetic model for FDFCC.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号