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921.
Xinru Xu Jingyi Yang Ying Jiang Jinsheng Gao 《Petroleum Science and Technology》2006,24(11):1307-1321
The efficiency of desalting for six crude oils was studied with a SY-1 dynamic simulation experimental installation. The demulsifier DC2 was examined for 1#, 2#, and 4# crude oil and DC4 was used for 3#, 5#, and 6# crude oil. The effects of temperature, electric field gradient, dosage of demulsifier, and washing water on the desalting efficiency of six crude oils were investigated. The results showed that at the optimization process condition after desalting, the desalting efficiency and the salt content of 1# crude oil reached 89.17% and 1.92 mg/L; that of 2# crude oil reached 85.08% and 1.04 mg/L; that of 3# crude oil reached 91.06% and 1.35 mg/L; that of 4# crude oil reached 81.67% and 1.51 mg/L; that of 5# crude oil reached 81.03% and 2.32 mg/L; and that of 6# crude oil reached 86.64% and 2.67 mg/L. Different crude oils have different metal contents. Three assistants, ammonium nitrate (TJ1), nitric acid (TJ3), and polyamine carboxylate (TJ4), were used to improve the efficiencies of desalting and demetalization of six crude oils. TJ4 was more efficient in removing calcium and iron for 1# and 2# crude oil. TJ1 was more efficient in desalting and demetalizing 5# crude oil. The efficiencies for removal of calcium, iron, nickel, and vanadium respectively reached 99.89%, 98.33%, 20.58%, and 43.02%. TJ3 has better efficiency desalting and demetalizing for 6# crude oil. With the concentration of TJ3 increasing from 0 to 80 mg/L, the desalting efficiency increases from 31.22% to 73.54%, and the iron removal efficiency increases from 56.0% to 74.05%. 相似文献
922.
We propose a simulation-based algorithm for inference in stochastic volatility models with possible regime switching in which the regime state is governed by a first-order Markov process. Using auxiliary particle filters we developed a strategy to sequentially learn about states and parameters of the model. The methodology is tested against a synthetic time series and validated with a real financial time series: the IBOVESPA stock index (São Paulo Stock Exchange). 相似文献
923.
Stress analysis of pin-loaded woven-glass fiber reinforced epoxy laminate conveying chain components
The aim of this study is to examine the effects of various loading conditions on the stress of a pin-loaded woven-glass fiber reinforced epoxy laminate conveying chain component. A numerical and experimental study was carried out to determine the stress distribution of composite conveying chain components used to convey loads. For the experimental study, an apparatus was developed to simulate chain components in real motion. Two different working conditions of the chain component were investigated. The first condition represents the movement of the chain components without loading. In the second condition, the chain component touches and moves the load. The commercial finite element package ANSYS was used to perform the numerical analysis using a three dimensional eight-noded layered structural solid elements. Chain tensile forces were loaded through pins and chosen as 250, 500, 750, 1000 and 1250 N for the two conditions of chain components. Experimental and numerical studies were compared and discussed for two conditions and five different tensile forces. A good agreement between experimental results and numerical predictions is obtained. 相似文献
924.
Yangjun Chen 《Information Processing Letters》2006,99(1):19-26
A precise analysis of the retrieval of signature trees is presented. A signature tree is a data structure constructed over a signature file to speed up searching all those signatures, which match a given query signature. The methods used include a detailed study of probabilistic analysis in conjunction with suitable contour integration of complex variabled functions. 相似文献
925.
Simultaneous HPLC quantification of total cholesterol,tocopherols and β-carotene in Barrosã-PDO veal 总被引:1,自引:0,他引:1
José A. Mestre Prates Mário A. Gonçalves Quaresma Rui J. Branquinho Bessa Carlos M.G. Andrade Fontes Cristina M.P. Mateus Alfaia 《Food chemistry》2006
A simple, rapid and sensitive procedure for the simultaneous determination of total cholesterol, tocopherols and β-carotene in meat is described. The method involves a direct saponification of the meat, a single n-hexane extraction and the analysis of the extracted compounds by normal-phase HPLC, using fluorescence (tocopherols) and UV–Vis photodiode array (cholesterol and β-carotene) detections in tandem. Rates of recovery of spiked meat samples were 93% for cholesterol, 83–86% for (α-, β- and -γ) tocopherols and 89% for β-carotene. Repeatabilities were high (CV < 6%) for all determined compounds, except for δ-tocopherol. This tocopherol, which is not usually present in meat, showed a much lower recovery percentage (73%) and repeatability (12.8%). This methodology was applied for the quantification of total cholesterol, tocopherols and β-carotene in three muscles (longissimus thoracis, longissimus lumborum and semitendinosus) of the Portuguese traditional Barrosã-PDO veal, obtained from autochthonous calves fed extensively during summer (with the least abundant green pastures) and slaughtered in early autumn (October). Barrosã-PDO veal showed median contents of total cholesterol (0.50–0.56 mg/g) and, depending on the analysed muscle, moderate to high contents of α-tocopherol (3.3–3.9 μg/g) and β-carotene (0.07–0.09 μg/g), suggesting an high sensorial and hygienic quality. 相似文献
926.
高坝风险分析的事件树法 总被引:2,自引:0,他引:2
新世纪一批高坝将要在我国开工建设,这对我国的水电能源及国民经济的发展有着不可估量的作用,而高坝建设中,安全性是需要首先保证的。目前对高坝的风险分析方法有主观概率法、客观概率法等。从系统工程的角度出发,采用事件树方法对高坝的风险进行了探索研究,并给出了算例以说明该方法的有效性和实用性。 相似文献
927.
928.
Jinsheng Que Qing Wang Jianping Chen Bingfei Shi Qinghui Meng 《Bulletin of Engineering Geology and the Environment》2008,67(4):479-483
The paper describes some geotechnical properties of the soft soils in Guangzhou College City, China, which are difficult to
both sample and test. Laboratory and in situ tests were carried out to assess the physical and mechanical indices of the soils.
The data were statistically analyzed and linear regression undertaken such that equations could be developed by which the
geotechnical properties of the soft soils can be predicted. The statistical validity of the degree of correlation confirmed
that using these equations, the mechanical indices can be estimated from physical indices determined by routine testing.
相似文献
929.
S. Sarkani T.A. Mazzuchi D. Lewandowski D.P. Kihl 《Engineering Fracture Mechanics》2007,74(18):2971-2980
Those individual tests in a series of experiments that are not completed or must be suspended are known as “censored points,” or “runouts”. Inclusion of runouts in data analysis can be problematic, and such ad hoc approaches as ignoring the runout observation or treating it as a failure can significantly affect estimation. The methodology offered here alleviates the handling of runouts and censored data by using the maximum likelihood estimation (MLE) method to incorporate the censored data properly. The methodology is illustrated with an example problem using actual data and the affects of ad hoc approaches are illustrated. 相似文献
930.
Tong Fang Mohsen A. Jafari Stephen C. Danforth Ahmad Safari 《Machine Vision and Applications》2003,15(2):63-75
This paper presents the concept of a process signature for the use of online signature analysis and defect detection in the layered manufacturing (LM) of ceramic sensors and actuators. To achieve the high quality of parts built by the fused deposition of ceramics (FDC), an online process-monitoring system is implemented to detect the processing defects. Using a process signature extracted from the image of a layer captured by the monitoring system, an ideal image is created that is then compared to the original image to detect and identify the defects. Some results of signature analysis and defect detection for single-material and multi-material parts are also presented.Received: 22 July 1999, Accepted: 21 October 2001, Published online: 29 October 2003
Correspondence to: Mohsen A. JafariThis work was supported by the Office of Naval Research under grant # N-0014-96-1-1175. Ref. US Patent # S-5738817, April 14, 1998. 相似文献