Athabasca油砂沥青焦化蜡油中富氮组分的分离与表征_英文_
Petroleum Science
2004 V ol.1 No.3
Separation and Characterization of Nitrogen-Rich Components
in Coker Gas Oils from Athabasca Bitumen
Xu Zhiming1, Zhao Suoqi1, J. R. Woods2, L. S. Kotlyar2 and K. H. Chung3
(1 State Key Lab. of Heavy Oil Processing, University of Petroleum, Beijing 102200, China)
(2 Institute for Chemical Process and Environmental Technology of NRC, Canada, K1A 0R6)
(3 Edmonton Research Centre, Syncrude Canada Ltd., Canada, T6N 1)
Received November 20, 2003
Abstract: It is well known that gas oils from oilsands bitumen are difficult to hydrotreat. In order to develop the most
appropriate flow sheet and operating conditions, a thorough knowledge of the molecular structure and behaviour of
bitumen and its gas oil products is needed. In this work, the gas oil samples are fractionated in an attempt to isolate and
identify the problematic molecular species for hydrotreating. It is found that the major nitrogen sources in coker gas oils
are associated with relatively small pentane insoluble species and an even smaller, highly polar, hexane insoluble species.
Structural information obtained for these fractions indicates that they are formed during the cracking of resin molecules.
Nitrogen speciation shows that the pyrroles are the primary nitrogen type, with pyridines also being an important species.
Both nitrogen species are undesirable in the hydrotreating process. Pyrroles in particular are subject to polymerisation,
producing gums and sediments that foul filters and other equipment while pyridines can directly deactivate the
hydrotreating catalyst.
Key words: Coker gas oil, pentane insoluble, hexane insoluble, separation, characterization
1. Introduction
The primary products from Athabasca bitumen coking are light and heavy gas oils. Although significant amounts of metals, sulfur and nitrogen are removed during coking, the heteroatom content of gas oils is unacceptably high and must be lowered in subsequent processing. It is well known that gas oils from bitumen are difficult to hydrotreat. Conventional catalysts in particular are degraded much more than expected owing to poisoning and difficulty of coking to hydrogenate nitrogen-bearing components. Nitrogen heterocycles may also contribute to processing problems through the formation of insoluble sediments and gums (Mushrush and Speight, 1995). Consequently, the amount and role of nitrogen-bearing components are of a special interest in the design of bitumen upgrading processes.
Gas oils are first treated with pentane to remove pentane insolubles quantitatively from each sample. A high performance liquid chromatography (HPLC) allows a further fractionation based on molecular polarity. Each fraction is characterized by several complementary analytical techniques and compared with similar data for other bitumen upgrading streams. Benchmarking samples include the insoluble end-cuts from Supercritical Fractionation & Extraction (SFE) of virgin bitumen pitch and fluid coking pitch ( Zhao, et al., 2001A; 2001B) together with the solubility class fractions (SARA) of the front-cuts derived from these pitch samples. The results are discussed in terms of the role played by nitrogen-rich components during bitumen upgrading.
2. Experimental
2.1 Samples
The samples used in this work were obtained from the bitumen upgrading plant at Syncrude Canada Ltd. Table 1 summarizes the source and identification for each sample.
Bitumen pitches are produced as the bottom fractions from atmospheric and vacuum distillation towers. Together, these pitches provide feedstock to a fluid coker. In this work, the Atmospheric-distillation Tower Bottom (ATB) fraction is used. In a one-time test, a coker is run in a once-through mode. The slurry formed during vapour washing in the coker is removed immediately instead of being recycled. After removal of volatiles the heaviest fraction from this operation is identified as Once-Through-Slurry-Bottom (OTSB). The major coker products are light and heavy gas oils that are blended to produce coker combined gas oil. Combined gas oils are mixed with vacuum heavy gas
Separation and Characterization of Nitrogen-Rich Components
73
V ol.1 No.3 oil and stored in a surge tank before passing through a Pall mesh filter (25 μm), just prior to hydrotreating. Since the syncrude upgrading process configuration was changed in 1999, these filters have been subject to severe plugging or fouling by gummy residues.
Table 1 Sample description and identification list
Streams Description IDs for
Separated
Fractions
Coker Heavy Gas Oil (GO-1) PI-1 Hydrotreater feed before filter (GO-2)
PI-2
Hydrotreater feed after filter (GO-3) PI-3
Coker Combined Gas Oil from Coker 1 (GO-4)
PI-4
Coker Gas Oils Coker Combined Gas Oil from Coker 2 (GO-5)
PI-5
Coking Pitch Fluid coking pitch from once through slurry mode (OTSB) OTSB-EC
Bottom fractions from atmospheric and distillation tower (A TB) ATB-EC SARA fractions: Saturates Aromatics Bitumen Pitch Resins 2.2 Sample separation
Pentane insolubles (PI) contents of gas oils were measured by dissolving the samples in equal volumes of toluene, followed by dilution with 40 volumes of n -pentane. This procedure is conducted at room temperature over a period of 8 hours. Precipitates are separated by filtration and the collected solids washed repeatedly with fresh pentane until the filtrates are colourless. Any toluene insoluble, or inorganic matter, is removed from the PI samples by a procedure described elsewhere ( Xu, et al .). The separated PI material amounts to only 0.2 to 0.4wt% of the parent gas oil samples.
The insolubles, or end-cut fractions from SFE of ATB and OTSB (Chung, et al ., 1997; Chung and Xu, 2001) are designated as ATB-EC and OTSB-EC. The inorganic minerals usually associated with these heavy fractions are quantitatively separated by an ultra- centrifugation procedure also described elsewhere (Kotlyar, et al., 1999). The soluble front-cuts from SFE are divided into saturates, aromatics and resins (SARA) by means of adsorption chromatography on alumina (The asphaltene fraction has been removed during SFE). HPLC group separation is carried out on the GO-1 using a preparative column (20mm ×250mm NH 2, from
Waters Ltd.) at a temperature of 40°C with hexane (5
mL/min) as the mobile phase. After 25 minutes, methyltertiarybutylether is introduced as a second solvent. The photodiode array detector collects UV signal data for wavelengths ranging from 240 to 400nm. Retention times for aromatic group separation are estimated from the chromatograph of a standard mixture containing each of the saturate, monoaromatic, diaromatic and polyaromatic compounds. It becomes apparent that, apart from saturates, mono- and diaromatics, the HPLC separation is based on molecular polarity rather than the number of aromatic rings.
2.3 Analyses Bulk elemental concentrations (carbon, hydrogen, nitrogen and sulfur) are determined with a CHNS analyser. A LECO VTF-900 analyser attachment provides oxygen contents. Gel Permeation Chromatography (GPC) provides number (MW n ) and weight (MW w ) average molecular weights based on calibration with polystyrene standards. Heteroatom
speciations (sulfur and nitrogen) are provided by X-ray
Photo-Electron Spectroscopy (XPS). Structural analysis data are obtained from Proton Nuclear Magnetic Resonance (1H-NMR) measurements. The average structural parameters are calculated
from the results of 1H-NMR, molecular weight and elemental analyses based on methods described elsewhere (Zhao, et al ., 2001A).
3. Results and discussion
Elemental analyses for the coker gas oils, ATB and OTSB are summarised in Table 2. The results for the five gas oil samples are similar and cover relatively narrow ranges. Compared with bitumen pitches, the gas oils have lower heteroatom contents but higher H/C ratios.
Table 2 Elemental analysis of gas oils and pitch samples Composition (w/w%)
Streams
C H N S
H/C
GO-1 84.71 11.26 0.53 4.45 1.60GO-2 82.59 10.39 0.34 4.19 1.51GO-3 80.72 11.05 0.36 4.02 1.64GO-4 81.15 10.10 0.33 4.23 1.49GO-5 82.76 10.18 0.39 3.97 1.48OTSB 83.90 8.40 0.80 5.60 1.20ATB 80.40 9.30 0.90 6.50 1.39
Petroleum Science
2004
74 3.1 Bitumen pitch fractions
The molecular weights, elemental analyses and average structural parameters for ATB-EC and SARA fractions from bitumen pitch are presented in Table 3. In terms of weight (MW w ) and number (MW n ) average molecular weights, the values for the aromatic and resin classes are similar. The resin fractions have slightly lower H/C atomic ratios but higher f a values; a comparison of the H au /C A ratios for the class members indicates that the resin samples are somewhat more condensed than the aromatics. Also, the δ parameter values show that aromatic rings in the resins are less substituted than those in the corresponding aromatic fractions. For both resins and aromatics the number of repeating units (n) in each molecule falls in the range of 1 to 1.4. On the other hand, the resins have a slightly higher number of aromatic rings (R a ) per unit than the corresponding aromatic fractions.
Table 3 Yield and characteristics of end-cut and SARA
fractions from bitumen pitch
In terms of heteroatoms, the aromatic fractions have higher sulfur contents than the corresponding resin class; in each case, thiophenic sulfur is the dominant type (see Table 3). A significant difference is that the nitrogen contents for the resin components are much higher than those found in the corresponding aromatic fractions. Only trace amounts of nitrogen are present in saturates.
The molecular units, or core structures, in the SARA fractions and ATB-EC show major differences in molecular weight, the number of repeating units (n), the number of aromatic rings (R a ) and the degree of aromatic ring condensation (H au /C A ). For the ATB-EC, these same parameters are significantly higher than those found in any of the SARA fractions. The ATB-EC, representing 40wt% of bitumen pitch, also accumulates most of the heteroatoms, i.e., 55wt% of nitrogen and 47wt% of sulfur, respectively. Another important observation is that the nitrogen concentrations in the resin class are even greater than those determined for the end-cut. In fact, the resins, representing only 18wt% of the original pitch, account for more than 30wt% of the total nitrogen.
3.2 Coker streams fractions
The results given in Table 4 demonstrate that there is little difference in MW n , MW w and H/C values for the pentane insolubles from five coker gas oils. Also, the
values for nitrogen and sulfur are similar, falling within the ranges of 1.7 to 2.4wt% and 5 to 5.7wt%,
respectively. These samples also have similar aromaticities (f a = 0.5 to 0.52) and are best represented by a single primary unit (n = 1). Each molecule in the
pentane insoluble (PI) fractions comprises approximately two naphthenic and three aromatic rings with a similar degree of ring condensation (H au /C A ).
The δ parameter values for these samples also show that
the aromatic rings are substituted to a similar extent by alkyl groups with comparable chain lengths (L).
Table 4 Characteristics of pentane insolubles separated
from coker streams
Pentane insolubles from coker gas oil Sample characteristics OTS
B-EC PI-1 PI-2 PI-3PI-4PI-5MW w 2328
660 802 753917925MW n 1014
384 425 398459479H/C 0.79
1.15 1.14 1.02 1.18
1.17N (wt%) 1.00 1.85
2.00 2.4 1.65 1.76O (wt%) 4.11
3.17 3.73 3.87 3.28 3.81Total S (wt%) 6.50
4.98
5.49 5.56 5.28
5.65Thiophenic sulfur (wt%)
6.0 3.3 3.8 3.6
3.7
4.0f a 0.670.51 0.51 0.520.50.52H au /C A 0.380.7 0.68 0.70.650.71δ 0.500.45 0.47 0.470.47
0.47
n 1 1 1 1 1 1
R a 15.4
3 3.3 3 3.7 2.8
Rn 4.3 2.4 2.5 2.5 2.4
1.9
L 3.7 3.3 3.6 3 4 4.3
SARA fractions from ATB front-cuts Sample
characteristics
Saturates Aromatics Resins
A TB-EC Overall yields (% of original
pitch)
6 36 18 40
M w 827 601-1720 587-1855 10890 M n 745 512-1079 493-1065 3137 H/C (atomic) 1.80 1.37-1.48 1.30-1.34 1.22 N (w%) 0.02 0.26-0.36 1.30-1.70 1.10 N (% of total N in pitch) <0.5 13 32 55 S (w%)
0.30 5.56-7.72 3.70 -5.98 7.2
S (% of total S in pitch) <0.5 39 14
47
Thiophenic sulfur (w%)
0.28 3.23-4.66 2.42-4.27 5.1
f a 0.11
0.31-0.37 0.39-0.41 0.45 H au
/C A
1.03 0.62-0.78 0.6-0.7 0.45 δ 0.87 0.52-0.62 0.52-0.54 0.55
n 1 1-1.4 1-1.4 2.9
R a 0 2.2-4.2 3-4.7 10.0 R n 3.4 2.4-2.7 2.5 3.1 L 4.1 4.3-6.1 4.3-5.8 6.3
Separation and Characterization of Nitrogen-Rich Components
75
V ol.1 No.3 There are obvious differences between bitumen pitch end-cut (ATB-EC) and coking pitch end-cut (OTSB-EC), when Tables 3 is compared with Table 4. The latter has a lower molecular weight, H/C atomic ratio and number of repeating units (n) per molecule. Compared with ATB-EC, the repeating units in OTSB-EC have a greater number (R a >15) of highly condensed (lower H au /C A ) aromatic rings with shorter alkyl substituents (lower L).
Preparative, chromatographic separation of GO-1 produces saturate and aromatic fractions plus three highly polar sub-fractions (POL-1, POL-2 and POL-3), where POL-2 and POL-3 are insoluble in hexane when separated from the parent sample. The yields, molecular weights and elemental analyses for these fractions are given in Table 5.
Table 5 Yields and analyses for HPLC fractions
HPLC fractions
Polars
Properties
Saturates Aromatics
POL-1 POL-2POL-3
Yield, wt% 23.5 40.2 22.5 11.5 2.3MW w 450 315 254 261 266MW n 330 216 187 212 226
H/C (atomic) 1.8 1.43 1.15 1.18 1.17
N (wt %) 0.1 0.12 0.64 2.22 2.95N (% of total N in pitch) 4 9 26 48 13 Pyrrolic nitrogen
(w%)
b.d.l. b.d.l. 0.3 1.9 2.4Pyridinic nitrogen (w%)
b.d.l. b.d.l. 0.3 0.2 0.2O (wt%) 0.4 0.6 1.0 2.5 2.9
O (% of total O in pitch) 8 27 25 32 8 S total (wt%) 0.20 4.12 7.60 5.00 4.48S (% of total S in pitch)
1 41 41 15 2
Thiophenic sulfur (wt%) b.d.l. 3.1 5.9 3.3 2.9b.d.l. = below detection limit
Here, we see that the saturate and aromatic fractions are associated with insignificant amounts of heteroatoms (nitrogen, oxygen and sulfur). However, both nitrogen and oxygen contents increase rapidly for samples POL-1 through POL-3. In fact, the combined POL-2 and POL-3 samples, representing only 14wt% of the parent gas oil, contain more than 60wt% of the total nitrogen and 40wt% of the oxygen. Results from XPS measurements on these samples point to pyrroles as the primary nitrogen species with pyridines also being significant. In each case, sulfur is mostly thiophenic in nature; the first polar sub-fraction (POL-1) had the highest sulfur content.
A comparison of the polar sub-fractions from coker heavy gas oil shows only marginal differences in molecular weights and average structural parameters (see Tables 5 and 6). In essence, each of the molecules has an average of two aromatic rings (R a ) with virtually the same aromaticity (f a ) and H/C atomic ratio. Also, the aliphatic chain lengths (L), the degree of aromatic ring substitution (δ) and condensation (H au /C a ) are similar.
Table 6 Average structural parameters for HPLC fractions HPLC fractions from KHGO Polars
Molecular parameter
Aromatics
POL-1 POL-2 + POL-3
f a 0.36 0.55 0.53 H au /C A 0.91 0.86 0.87
δ
0.57 0.47 0.48 n 1 1 1
R a 1.3 1.6 1.6 Rn 2 1.7 1.7 L 4.5 3.4 3.7
4. Origin of the nitrogen-rich components and their roles during bitumen upgrading It is well known that the pentane insoluble, or end-cut fraction, is the most problematic component of Athabasca bitumen pitch. This fraction is the major source for coke formation under thermal cracking conditions. Carry-over of this component from the coker may also be partly responsible for fast catalyst deactivation during hydrotreating. An average molecule in the end-cut fraction comprises polyaromatic “core” structures and associated heteroatoms (N, thiophenic S) in three repeating units. Aliphatic sulfides, n-alkanes or metals act as bridges between these units (Speight, 1991). Pentane soluble resin material, with a high nitrogen content, is another potentially troublesome fraction present in bitumen pitch. Compared with molecules in the end-cut
fraction, resins are smaller and contain fewer repeating units, each with less condensed aromatic rings. Although the results of structural analysis point to a high degree of aromatic ring condensation, especially for end-cut molecules, a more open structure, visualized as a collection of interconnected smaller units, cannot be ruled out (Speight, 1991). The thermal reactions occurring during coking involve the cracking of side chains, bridges and sulfide linkages together with an aromatisation of aliphatic structures. Although the aromatic rings are fairly stable at moderate cracking temperatures (350-500oC), condensed aromatics
Petroleum Science 2004 76
may undergo ring destruction (Speight, 1991). Thermolysis of aryl-alkyl bonds can be enhanced by the presence of nickel, vanadium, heterocyclic nitrogen and other heteroatoms. Free radical formation during the cracking is accompanied by condensation reactions. When such reactions involve the heavy “core” molecules in a pitch, like A TB-EC, the result is coke formation.This view is consistent with the observed accumulation of nitrogen and sulfur species in bitumen coke.Even though some condensation products are still soluble in toluene, they remain with the residue. An example is the highly aromatic, single-unit, OTSB-EC material.
Under thermal cracking conditions, the majority of cracked resin molecules report the product stream, i.e., as a coker gas oil component. The thermal reactions, including fragmentation of polyaromatic structures, cause a decrease in overall molecular weight and size, average number of aromatic rings and chain length of aliphatic substituents. These reactions produce a concomitant increase in aromaticity. Because nitrogen functional groups tend to be more stable to thermolysis, the nitrogen content of the cracked molecules increases, compared to the parent resin molecules. Based on this logic, the resin fraction must be the primary source of the pentane insoluble and hexane insoluble, polar HPLC fractions (POL-2 and POL-3). The most remarkable feature of these fractions is their high nitrogen content. For example, POL-2 and POL-3 constitute only 14wt% of the gas oil but are associated with more than 60wt% of the total nitrogen.
The presence of nitrogen-rich species in gas oil has important implications for industrial processes. Pyrroles may be the key factor in the formation of insoluble sediments and gums in coker gas oils during downstream processing (Mushrush and Speight, 1995). The solubility of this polar material may be further decreased by adsorption onto a small amount of iron and clay minerals also present in gas oil. These minerals are known for their ability to interact with polar crude oil components (Wang, et al., 1998; Cosultchi, et al., 2001). This combination of polar nitrogen-rich species and mineral solids is believed to be the problematic foulant observed on filters and other equipment during hydrotreating. In addition to the problems associated with neutral pyrroles, the presence of basic pyridines will deactivate the hydrotreating catalyst by neutralizing acid sites.
5. Conclusions
Coker gas oils contain a significant amount of nitrogen-rich material with a relatively low molecular weight. Structural information indicates that these molecules are formed in the cracking of the resin fraction originally present in bitumen. Nitrogen speciation shows that pyrroles are the primary nitrogen species followed by pyridines. Both of these nitrogen species are undesirable in hydrotreating processes. Pyrroles in particular, polymerize to produce filter-fouling gums and sediments while pyridines may directly deactivate the hydrotreating catalyst. References
Chung, K., Xu, C. and Hu, Y. (1997) “Super-critical Fluid Extraction Reveals Resid Properties ”, Oil and Gas Journal, 95(3): 66
Chung, K. H. and Xu, C. (2001) “Narrow-cut Characterization Reveals Resid Process Chemistry”, Fuel, 80, 1165 Cosultchi, A., Garciafigueroa, E., Carcia-Borquez, A., Reguera, E., Y ee-Madeira, H., Lara, V. H., Bosch, P. (2001) “Petroleum Solid Adherence on Tubing Surface”, Fuel, 80, 1963-1968
Kotlyar, L. S., Sparks, B. D., Woods, J. R. and Chung, K. H.
(1999) “Solids Associated with the Asphaltene Fraction of Oilsands Bitumen”, Energy and Fuels, 13, 346-350 Mushrush, G. W. and Speight, J. G. ( 1995 ) “Petroleum Products: Instability and Incompatibility(Applied Energy Technology Series)”, Tailor & Francis, Washington
Speight, J. G. (1991) “The Chemistry and Technology of Petroleum”. Marcel Dekker Inc., New York
Wang, S., Chung, K. H., Masliyah, J. H. and Gray, M. R. (1998) “Toluene-insoluble Fraction from Thermal Cracking of Athabasca Gas Oil: Formation of a Liquid-in-oil Emulsion That Wets Hydrophobic Dispersed Solids”, Fuel, 77(14), 1647-1653
Xu, Z., Wang, Z., Kung, J., Woods, J. R., Chung, K. H., Kotlyar, L.
S., Sparks, B. D. and Wu, X., “Separation and Identification of Suspended Solids in Coker Gas Oil from Athabasca Bitumen”, Fuel, submitted
Zhao, S., Kotlyar, L. S., Woods, J. R., Sparks, B. D. and Chung, K.
H. (2001A) Effect of Thermal and Hydrocatalytic Treatment on
the Molecular Chemistry of Narrow Fractions of Athabasca Bitumen Pitch, Energy and Fuels, 15(1), 113-119
Zhao, S., Kotlyar, L. S., Woods, J. R., Sparks, B. D., Hardacre, K. and Chung, K. H. (2001B) “Molecular Transformation of Athabasca Bitumen End-cuts During Coking and Hydrocracking”, Fuel, 80, 1155-1163
About the first author
Xu Zhiming, male, born in 1969, is
an associate professor at the State Key
Laboratory of Heavy Oil Processing in
the University of Petroleum (Beijing).
He received his MS degree in chemical
engineering from the University of
Petroleum in 1994. His major research interests cover heavy oil processing and supercritical fluid technology. E-mail address: scf@https://www.wendangku.net/doc/0116858381.html,
(Edited by Zhu Xiuqin)
Separation and Characterization of Nitrogen- Rich Components 77 V ol.1 No.3
Athabasca油砂沥青焦化蜡油中富氮组分的分离与表征
许志明1赵锁奇1 J.R. Woods 2 L.S. Kotlyar2 K.H Chung 3
（1 石油大学重质油国家重点实验室, 中国北京昌平 102200）
（2 加拿大国家研究院化工过程与环境技术研究所, 加拿大渥太华K1A 0R6）
（3 加拿大合成油公司埃德蒙顿研究中心，加拿大埃德蒙顿 T6N 1H4）
摘要：油砂沥青焦化蜡油的加氢处理是比较困难的，为了选择合适的加工流程和操作条件，有必
要对油砂沥青及其焦化蜡油的分子结构有更全面的认识。本研究尝试分离和鉴别焦化蜡油中对加
氢过程不利的组分。研究发现，焦化蜡油中主要的富氮组分是较小分子的戊烷不溶物，或者是更
小分子、极性较强的己烷不溶物。组分的结构信息表明它们是由胶质分子裂化反应后形成的。吡
咯类化合物是主要的氮化物类型，其次是吡啶类化合物。这两类氮化物都对加氢过程不利，如吡
咯类化合物容易聚合产生胶质和沉淀，堵塞过滤器和其它设施；而吡啶类物质能直接导致加氢催
化剂失活。
关键词：焦化蜡油戊烷不溶物己烷不溶物分离表征
（continued from page 48）
定量描述非均质油藏化学驱波及效率和驱替效率的作用
沈平平袁士义邓宝荣宋杰沈奎友
（中国石油勘探开发研究院，中国北京 100083）
摘要：本文利用我国自行研制的ASP数值模拟软件,采用正韵律二维剖面地质模型，分别模拟
了水驱、聚合物驱、三元复合驱的驱油过程，分层计算了采收率、剩余油饱和度、波及效率
和驱替效率，进行了指标对比。通过研究表明对于非均质严重的油藏，不同层段的波及效率
和驱替效率所起的作用不同。高渗层以提高驱替效率为主，低渗层以提高波及效率为主，中
等渗透层提高波及效率和提高驱替效率相当。由于水驱后，剩余油大部分集中在上部，低渗
透层是提高采收率主要潜力所在，提高上部低渗透层的波及效率对于提高总体采收率具有重
要的作用。对于非均质严重的油藏，先调剖再注三元复合体系段塞是提高化学驱油效果的重
要途径。
关键词：化学驱驱替效率波及效率提高采收率非均质油藏
数据库信息管理系统简介外文翻译
附录A Introduction to database information management system The database is stored together a collection of the relevant data, the data is structured, non-harmful or unnecessary redundancy, and for a variety of application services, data storage independent of the use of its procedures, insert new data on the database, revised, and the original data can be retrieved by a common and can be controlled manner. When a system in the structure of a number of entirely separate from the database, the system includes a "database collection". Database management system is a manipulation and large-scale database management software is being used to set up, use and maintenance of the database. Its unified database management and control so as to ensure database security and integrity. Database management system users access data in the database, the database administrator through Database management system database maintenance work. It provides a variety of functions, allows multiple applications and users use different methods at the same time or different time to build, modify, and asked whether the database. It allows users to easily manipulate data definition and maintenance of data security and integrity, as well as the multi-user concurrency control and the restoration of the database. Using the database can bring many benefits: such as reducing data redundancy, thus saving the data storage space; to achieve full sharing of data resources, and so on. In addition, the database technology also provides users with a very simple means to enable users to easily use the preparation of the database applications. Especially in recent years introduced micro-computer relational database management system , intuitive operation, the use of flexible, convenient programming environment to extensive (generally 16 machine, such as IBM / PC / XT, China Great Wall 0520, and other species can run software), data-processing capacity strong. Database in our country are being more and more widely used, will be a powerful tool of economic management. The database is through the database management system (DBMS-DATA BASE
(完整版)数据库重要术语(中英文)
单词汇总(数据库专业一点的词汇其实主要就是每章后面review items的内容，在这里简单列一 下，如果你实在没时间看书，至少这些单词要认识。)： 1. 数据库系统：database system(DS),database ma nageme nt system(DBMS) 2. 数据库系统(DS)，数据库管理系统(DBMS) 3. 关系和关系数据库table= relation，column = attribute 属性，domain, atomic domain, row= tuple ， relati onal database, relati on schema, relati on in sta nee, database schema, database in sta nee; 4. 表=关系，列=属性属性，域，原子域，排=元组，关系型数据库，关系模式，关系实例，数 据库模式，数据库实例； 1. key 们：super key, can didate key, primary key, foreig n key, referencing relati on, referen ced relati on; 2. 超码，候选码，主码，外码，参照关系，被参照关系 5. 关系代数(relational algebra): selection, project, natural join, Cartesian product, set operations, union, in tersect, set differe nee ( except\m in us), Ren ame, assig nment, outer join, group ing, tuple relati on calculus 6. (关系代数)：选择，项目，自然连接，笛卡尔积，集合运算，集，交集，集合差(除负)， 重命名，分配，外连接，分组，元组关系演算 7. sql组成： DDL :数据库模式定义语言，关键字：create DML :数据操纵语言，关键字：Insert、delete、update DCL :数据库控制语言，关键字：grant、remove DQL :数据库查询语言，关键字：select 8. 3. SQL 语言：DDL，DML，DCL，QL，sql query structure, aggregate functions, nested subqueries, exists(as an operator), uni que(as an operator), scalar subquery, asserti on, in dex(i ndices), catalogs, authorization, all privileges, granting, revoking , grant option, trigger, stored procedure, stored fun cti on 4. SQL语言：DDL，DML，DCL，QL，SQL查询结构，聚合函数，嵌套子查询，存在(如运 营商)，独特的(如运营商)，标量子查询，断言指数(指数) ，目录，授权，所有权限，授 予，撤销，GRANT OPTION，触发器，存储过程，存储函数 8. 表结构相关：Integrity constraints, domain constraints, referential integrity constraints 9. 完整性约束，域名约束，参照完整性约束 5. 数据库设计(ER 模型)：Entity-Relationship data model, ER diagram, composite attribute, sin gle-valued and multivalued attribute, derived attribute, binary relati on ship set, degree of relati on ship set, mapp ing card in ality, 1-1, 1-m, m-n relati on ship set (one to one, one to many, many to many), participati on, partial or total participati on, weak en tity sets, discrim in ator attributes, specialization and generalization 6. 实体关系数据模型，ER图，复合属性，单值和多值属性，派生属性，二元关系集，关系集， 映射基数的程度，1-1，1-米，MN关系集合(一对一，一对多，多对多) ，参与部分或全部参与，弱实体集，分辨符属性，特化和概化 10. 函数依赖理论：functional dependence, normalization, lossless join (or lossless) decomposition, First Normal Form (1NF), the third normal form (3NF), Boyce-codd normal form (BCNF), R satisfies F, F
我国高校图书馆外文电子图书数据库建设现状及发展对策研究
我国高校图书馆外文电子图书数据库建设现状及发展对策研究 （作者:___________单位: ___________邮编: ___________） [摘要] 利用网络对我国高校图书馆外文电子图书数据库的建设情况展开调查,并依据调查结果分析了外文电子图书数据库的建设现状及存在的问题,最后提出了优化我国高校图书馆外文电子图书数据库建设的对策。 [关键词]外文电子图书; 数据库;高校图书馆 人类文化已步入以数字技术为依托的数字化出版时代,电子图书的出现是信息时代文献信息技术发展的必然产物。随着高等教育的快速发展,为了进一步满足广大读者对文献信息资源的多元化、高层次需求,越来越多的高校开始重视电子图书数据库的建设。外文图书是国外最新科学技术研究成果的总结,具有较高的理论水平和学术价值,能迅速反映国外各领域的最新理论成果,尤其是对于高校师生的教学科研工作具有极高的参考价值。近年来,由于各高校图书馆的购书经费相对短缺以及外文原版图书订购费用高、利用率低
等原因,外文图书的采购量呈逐年下滑趋势,而高校读者对外文资料的需求却在日益上升。[1]因此,通过网络调查分析我国高校图书馆外文电子图书数据库建设的现状,找出存在的问题,并提出相应的发展对策,具有重要的意义。 1 我国高校图书馆外文电子图书数据库建设现状 1.1 研究方法 笔者于2009年6月10—15日,根据中国教育和科研计算机网(www. edu. cn)提供的全国普通高校名单,采取直接登录网站网页的方式,依据学校办学能力及性质相似的原则,筛选出全国各省市60所有代表性的高校,其中“211高校”30所、省属二本以上高校30所。本论文主要利用网络调查的方法对外文电子图书数据库的建设现状进行调查,并利用统计学知识对数据进行分析。[LL] 1.2研究结果 1.2.1 外文电子图书数据库的来源分析。在被调查的60所高校图书馆中,71.67%的图书馆收藏有外文电子图书资源。这些资源主要来自以下5个渠道:第一是电子书商。这是最主要、最重要的来源,电子书商通过其商业化的运作模式,往往在提供的图书数量上占绝对优势,其提供的检索软件功能也比较全面,如NetLibrary专为图书馆定制的TitleSelect和TitleDirect功能模块,可以在网上提交订单,这些功能使电子图书的订购过程更加流畅。第二,单独一家出版社或几家出版社联合组建的电子图书公司。它们往往无法在图书数
数据库管理系统中英文对照
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数据库英文版第六版课后答案 (45)
C H A P T E R24 Advanced Application Development Exercises 24.6Find out all performance information your favorite database system pro- vides.Look for at least the following:what queries are currently executing or executed recently,what resources each of them consumed(CPU and I/O),what fraction of page requests resulted in buffer misses(for each query,if available),and what locks have a high degree of contention.You may also be able to get information about CPU and I/O utilization from the operating system. Answer: ?Postgresql:The E XP L AI N command lets us see what query plan the system creates for any query.The numbers that are currently quoted by E XP L AI N are: a.Estimated start-up cost b.Estimated total cost c.Estimated number of rows output by this plan node d.Estimated average width of rows ?SQL:There is a Microsoft tool called SQL Pro f iler.The data is logged, and then the performance can be monitored.The following perfor- mance counters can be logged. a.Memory b.Physical Disk c.Process d.Processor e.SQLServer:Access Methods f.SQLServer:Buffer Manager g.SQLServer:Cache Manager 191
数据库工程师专业英文整理
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国内外常用数据库介绍
国内外常用数据库介绍 一、中国 1、中国知网(CNKI) 中国知识基础设施工程（China National Knowledge Infrastructure,CNKI）是由清华同方光盘股份有限公司、清华大学中国学术期刊电子杂志社、光盘国家工程研究中心联合建设的综合性文献数据库,于1999年6月在CERNET上开通了中心网站(),在CHINANET上开通了第二中心网站(),并且在许多图书馆和情报单位建立了镜像站点。目前CNKI已建成了中国期刊全文数据库、优秀博硕士学位论文数据库、中国重要报纸全文数据库、重要会议论文全文数据库、科学文献计量评价数据库系列光盘等大型数据库产品，中国期刊全文数据库为其主要产品之一。 CNKI中国期刊全文数据库（Chinese Journal Full-text Database，CJFD）收录了1994年至今的6600种核心期刊与专业特色期刊的全文,积累全文文献618万篇，分为理工A（数理化天地生）、理工B（化学化工能源与材料）、理工C（工业技术）、农业、医药卫生、文史哲、经济政治与法律、教育与社会科学、电子技术与信息科学9个专辑,126个专题文献数据库。网站及数据库交换服务中心每日更新,各镜像站点通过互联网或光盘来实现更新。（免费帐号及密码） 2、中文科技期刊数据库/维普数据库（VIP） 由科技部西南信息中心直属的重庆维普资讯公司开发，收录1989年以来8000余种中文期刊的830余万篇文献，并以每年150万篇的速度递增。维普数据库按照《中国图书馆图书分类法》进行分类，所有文献被分为7个专辑：自然科学、工程技术、农业科学、医药卫生、经济管理、教育科学和图书情报,7大专辑又进一步细分为27个专题。（免费帐号及密码） 3、万方数据知识服务平台（wanfangdata） 万方数据股份有限公司是国内第一家以信息服务为核心的股份制高新技术企业，是在互联网领域，集信息资源产品、信息增值服务和信息处理方案为一体的综合信息服务商。它集纳了涉及各个学科的期刊、学位、会议、外文期刊、外文会议等类型的学术论文，法律法规，科技成果，专利、标准和地方志。期刊论文：全文资源。收录自1998年以来国内出版的各类期刊6千余种，其中核心期刊2500余种，论文总数量达1千余万篇，每年约增加200万篇，每周两次更新。（免费帐号及密码） 4、中国科学引文数据库(CSCD) 中国科学引文数据库（Chinese Science Citation Database,CSCD）创建于1989年，1999年起作为中国科学文献计量评价系列数据库（ASPT）的A辑，由中国科学院文献情报中心与中国学术期刊电子杂志社联合主办，并由清华同方光盘电子出版社正式出版，是我国最大、最具权威的科学引文索引数据库—中国的SCI,为我国科学文献计量和引文分析研究提供了强大的工具。 CSCD收录了国内数学、物理、化学、天文学、地学、生物学、家林科学、医药卫生、工程技术、环境科学和管理科学等领域的中英文科技核心期刊和优秀期刊，其中核心库来源期刊为650种。 5、全国中西日俄文期刊联合目录数据库 是全国性的连续出版物联合目录数据库。数据库报道国内400多家图书情报单位收藏的中西日俄文期刊10万余种，收录的单位遍及中国科学院全院和北京地区各大图书情报单位以及国内一些大的图书情报单位。如中科院文献情报中心、中信所、北京大学图书馆、清华大学图书馆、国防科工委情报所、医科院图书馆、农科院图书馆等。从2000年起，数据库在国内率先对网络期刊进行系统的收集与编目，目前数据库收录网络西文期刊5194种，
数据库重要术语(中英文)
单词汇总（数据库专业一点的词汇其实主要就是每章后面review items的内容，在这里简单列一下，如果你实在没时间看书，至少这些单词要认识。）： 1.数据库系统：database system(DS),database management system(DBMS) 2.数据库系统（DS），数据库管理系统（DBMS） 3.关系和关系数据库table= relation，column = attribute属性，domain, atomic domain, row= tuple， relational database, relation schema, relation instance, database schema, database instance; 4.表=关系，列=属性属性，域，原子域，排=元组，关系型数据库，关系模式，关系实例，数 据库模式，数据库实例; 1.key们: super key, candidate key, primary key, foreign key, referencing relation, referenced relation; 2.超码，候选码，主码，外码，参照关系，被参照关系 5.关系代数(relational algebra)：selection, project, natural join, Cartesian product, set operations, union, intersect, set difference ( except\minus), Rename, assignment, outer join, grouping, tuple relation calculus 6.（关系代数）：选择，项目，自然连接，笛卡尔积，集合运算，集，交集，集合差（除\负）， 重命名，分配，外连接，分组，元组关系演算 7. sql组成： DDL：数据库模式定义语言，关键字：create DML：数据操纵语言，关键字：Insert、delete、update DCL：数据库控制语言，关键字：grant、remove DQL：数据库查询语言，关键字：select 8. 3.SQL语言：DDL，DML，DCL，QL，sql query structure, aggregate functions, nested subqueries, exists(as an operator), unique(as an operator), scalar subquery, assertion, index(indices), catalogs, authorization, all privileges, granting, revoking, grant option, trigger, stored procedure, stored function 4.SQL语言：DDL，DML，DCL，QL，SQL查询结构，聚合函数，嵌套子查询，存在（如运 营商），独特的（如运营商），标量子查询，断言指数（指数），目录，授权，所有权限，授予，撤销，GRANT OPTION，触发器，存储过程，存储函数 9.表结构相关：Integrity constraints, domain constraints, referential integrity constraints 10.完整性约束，域名约束，参照完整性约束 5.数据库设计(ER 模型)：Entity-Relationship data model, ER diagram, composite attribute, single-valued and multivalued attribute, derived attribute,binary relationship set, degree of relationship set, mapping cardinality,1-1, 1-m, m-n relationship set (one to one, one to many, many to many), participation, partial or total participation, weak entity sets, discriminator attributes, specialization and generalization 6.实体关系数据模型，ER图，复合属性，单值和多值属性，派生属性，二元关系集，关系集， 映射基数的程度，1-1，1-米，MN关系集合（一对一，一对多，多对多），参与部分或全部参与，弱实体集，分辨符属性，特化和概化 11.函数依赖理论：functional dependence, normalization, lossless join (or lossless) decomposition, First Normal Form (1NF), the third normal form (3NF), Boyce-codd normal form (BCNF), R satisfies F, F holds on R, Dependency preservation保持依赖, Trivial, closure of a set of functional dependencies函数依赖集的闭包, closure of a set of attributes属性集闭包,
【计算机专业文献翻译】数据库构建
数据库构建 从用户界面要素构建数据库应用，描述数据库为信息的组成部分(数据集)，以及连结这些对彼此和对数据库信息的来源的组成部分。你怎样组织这些片，就是你的数据库应用的结构。 当有很多清楚的方法在数据库应用中组织组成部分时，大多数遵循用下列数字说明的一般的计划： 1．用户界面形式 在形式上把它完全与其余应用分开的隔离用户界面是一种好想法。这有几个优势。通过把用户界面从描述数据库信息的组成部分本身隔离开，你把一种更大的灵活性引入你的设计：转换成你管理数据库信息的方式，不要求你重写你的用户界面；换成用户界面不要求你兑换与数据库合作的你应用的部分。另外，这类隔离让你发展你能在多应用之间分享的普通形式，因此提供一个一致的用户界面。通过储存与类库方面的精心设计的形式的联系，你和其他开发者能在现有的基础而不是为每项新工程从头开始建造。分享形式也使你得以发展应用接口的共同的标准。关于在数据库应用中创建用户界面的更多信息，参见用户界面的设计。 2．数据控件 如果你已经隔离你的用户界面进它自己的形式，你可以使用一个数据模件存放描述数据库信息的零部件( 数据集)，以及把这些数据集和你的应用的其它部分连结起来的组成部分。像用户界面形式一样，你在类库中能分享数据控件，以便他们可能在应用中被重新使用或者共享。 3．数据源 在数据模件里的第一条是一个数据源。在用户界面和从数据库那里描述信息的一数据集之间，数据源担任一导管。几个意识到数据的关于一个形式的控制能分享一个单个的数据源，在这种情况下在每个控制过程中的展示能够协调以便用户卷轴通过记录，在当前所记的领域的相应价值中被在每个控制过程中展示。 4.数据集 你的数据库应用的核心是数据集。这个组成部分在基础的数据库中代表一套记录。这些记录可能是来自一份单数据库表，来自一张表多个领域或多个记录，或来自于多个表的视图。在使用数据集时，你应用逻辑是在数据库缓存内重建的物理表。当基础的数据库改变时，你可能需要改变数据集控制的数据的方式，但是你的其余应用能继续工作而没有改变。欲了解关于数据集的共同特性和方法的更多的信息，参见理解数据集 5. 数据链接
数据库系统概念英文第六版所有的建表语句和插入的数据
CREATE DATABASE IF NOT EXISTS `university` /*!40100 DEFAULT CHARACTER SET gbk */; USE `university`; -- MySQL dump 10.13 Distrib 5.6.13, for Win32 (x86) -- -- Host: localhost Database: university -- ------------------------------------------------------ -- Server version 5.7.4-m14 /*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */; /*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */; /*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */; /*!40101 SET NAMES utf8 */; /*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */; /*!40103 SET TIME_ZONE='+00:00' */; /*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */; /*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */; /*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */; /*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */; -- -- Table structure for table `advisor` -- DROP TABLE IF EXISTS `advisor`; /*!40101 SET @saved_cs_client = @@character_set_client */; /*!40101 SET character_set_client = utf8 */; CREATE TABLE `advisor` ( `s_ID` varchar(5) NOT NULL, `i_ID` varchar(5) DEFAULT NULL, PRIMARY KEY (`s_ID`), KEY `i_ID` (`i_ID`), CONSTRAINT `advisor_ibfk_1` FOREIGN KEY (`i_ID`) REFERENCES `instructor` (`ID`) ON DELETE SET NULL, CONSTRAINT `advisor_ibfk_2` FOREIGN KEY (`s_ID`) REFERENCES `student` (`ID`) ON DELETE CASCADE ) ENGINE=InnoDB DEFAULT CHARSET=gbk; /*!40101 SET character_set_client = @saved_cs_client */; -- -- Dumping data for table `advisor` -- LOCK TABLES `advisor` WRITE;
中英文数据库
中英文数据库信息检索策略比较的案例分析 【摘要】：随着网络信息资源的迅猛增长,使人们获得有用信息越来越困难,网络检索工具应运而生,本文主要针对三大中文数据库，即中国知网、维普、万方，和两个英文数据库，即Springerlink和Elservier，的检索策略做出比较分析。【关键词】：数据库中英文检索策略对比注册会计师 The analysis of the cases about comparing retrieval strategies of database information in Chinese with that in English Zhang Bingjie 【Abstract】:With the rapid growth of network information resource, people acquiring useful information is becoming more and more difficult.The network retrieval tools came into being.This paper focuses on analyzing the comparison between the retrieval strategy of three big Chinese databases, namely CNKI, VIP, WANFANG DATA, and two English databases, namely Springerlink and Elservier. 【Keywords】:Database Chinese English Retrieval strategies Compare Springerlink 一、CNKI中国知网数据库
中外文数据库简介(部分)
中文数据库 （1）中国国家图书馆 中国国家图书馆馆藏宏富，品类齐全，古今中外，集精撷萃。截止2003年底，馆藏文献已达2411万册（件），居世界国家图书馆第五位，并以每年60-70万册（件）的速度增长。国家图书馆的藏书可上溯到700多年前的南宋皇家缉熙殿藏书，最早的典藏可以远溯到3000多年前的殷墟甲骨。国家图书馆的珍品特藏包括善本古籍、金石拓片、古代舆图、敦煌遗书、少数民族图籍、名人手稿、革命历史文献、家谱、地方志和普通古籍等260多万册（件）。外文善本中最早的版本为1473－1477年间印刷的欧洲“摇篮本”。这部分藏品极为珍贵，闻名遐迩，世界瞩目。 国家图书馆全面入藏国内正式出版物，是世界上入藏中文文献最多的图书馆。同时重视国内非正式出版物的收藏，是国务院学位委员会指定的博士论文收藏馆，图书馆学专业资料集中收藏地，全国年鉴资料收藏中心，并特辟香港、台湾、澳门地区出版物专室。 （2）中国科学院国家图书馆 中国科学院国家科学图书馆于2006年3月由中国科学院所属的文献情报中心、资源环境科学信息中心、成都文献情报中心和武汉文献情报中心四个机构整合而成，实行理事会领导下的馆长负责制。是我国的国家级科技文献情报机构，拥有藏书1140万册，中外期刊1.6万种。总馆设在北京，下设兰州、成都、武汉三个二级法人分馆，并依托若干研究所（校）建立特色分馆。全馆现有员工470余人，馆舍建筑面积8万平方米，依托网络提供高速、便捷的科技信息服务。 （3）国家科技图书文献中心 国家科技图书文献中心（NSTL）是根据国务院领导的批示于2000年6月12日组建的一个虚拟的科技文献信息服务机构，成员单位包括中国科学院文献情报中心、工程技术图书馆（中国科学技术信息研究所、机械工业信息研究院、冶金工业信息标准研究院、中国化工信息中心）、中国农业科学院图书馆、中国医学科学院图书馆。目前拥有3大类21个数据库，包括期刊论文、会议文献、学位论文、科技报告、专利文献、标准文献、计量检定规程等，文种涉及中、西、俄、日。 （4）中国高等教育文献保障系统 中国高等教育文献保障系统（China Academic Library & Information System,简称CALIS），是经国务院批准的我国高等教育“211工程”“九五”“十五”总体规划中三个公共服务体系之一。CALIS的宗旨是,在教育部的领导下，把国家的投资、现代图书馆理念、先进的技术手段、高校丰富的文献资源和人力资源整合起来，建设以中国高等教育数字图书馆为核心的教育文献联合保障体系，实现信息资源共建、共知、共享，以发挥最大的社会效益和经济效益，为中国的高等教育服务。CALIS管理中心设在北京大学，下设了文理、工程、农学、医学四个全国文献信息服务中心，华东北、华东南、华中、华南、西北、西南、东北七个地区文献信息服务中心和一个东北地区国防文献信息服务中心。 (5)读秀 读秀学术搜索是目前全世界最完整的文献搜索及获取服务平台，其后台建构在由北京世纪超星有限责任公司在18年来所数字化的215万种图书元数据组成的超大型数据库基础上。以9亿页中文资料为基础，为读者提供深入内容的章
期刊英文Ei数据库要求
文件3 《工程力学》中英文摘要参考准则(简称“英文准则”) ———自《Ei数据库文摘要求》摘编 一、总则 文摘是沟通国内外学者之间学术交流的桥梁，主要功能是提供信息，反映作者的原创性工作。文摘是一篇有内容的、完全独立的文章，读者不看正文和参考文献，只看文章摘要就能大致了解作者的工作。因此，文摘用语要通俗、简练、准确，客观、清晰地反映论文的基本内容和研究成果，即作者作了什么，怎么作的，结果是什么。 二、如何写好中英文摘要 1.文摘应包含正文的要点，一般来说应包含研究对象（目的），研究方法（所用的设备、材料），结果和结论。不能因为某些内容不好翻译就弃掉要点。 2.尽量简短，不介绍课题研究的背景信息(Background Information)，文摘中不能出现图号、表号、方程号及参考文献号。 3.文摘中尽量不出现数据，必要时应该是最重要、最关键的数据。 4.不用谦虚词，不用“据我所知”之类的不肯定词，直接说作了什么。对自己的工作不作评价。 5.文摘不能出现正文中没有的内容，不能对原文进行补充和修改。 6.文摘中的缩写名称在第一次出现时用括号写明全称。 7.中英文摘要内容要一致。 三、英文摘要行文原则 (一) 明确而简洁 1、尽量用短句。使用简短且词义清楚并为人所熟知词汇，不得使用行话和俗语，避免多姿多态的文学性描述。 2、取消不必要的词语：如“It is reported…”“Extensive investigations show that…”，“The author discusses…”“After careful comparison of…”以及文摘开头的“In this paper, ”。对一些不必要的修饰词，如“in detail”、“briefly”、“here”、“new”、“mainly”也尽量不要。 3、只叙述新情况，新内容，过去的研究细节及未来计划均不应列入； 4、不说无用的话，如“本文所谈的有关研究工作是对过去老工艺的一个极大的改进”等； 5、尽量简化用辞，删繁就简。参看右表。 6、文摘第一句应避免与题目(Title)重复。 (二) 采用正确的英语文体风格 1、用过去时态叙述作者做过的实验工作、实验过程 或曾经用过的技术，用过去时叙述的工作往往是不在文 章中详细叙述其过程的。推荐作者用现在时态叙述作者 文章中的内容(如理论依据、推导方法等)和文章结论：如 “The results of experiments for the natural frequencies and tension of a cable corresponding to a scale model of a guy wire for a 380m tall radio navigation tower are compared to the theoretical predictions. For the theoretical determination of natural frequencies, alternate methods of using curvature are presented. The first 10 natural frequencies of the cable were measured at a number of different wire tension levels and were found to differ from the theoretical values by an average of only 0.6%. The experimental results for the frequencies show clear evidence of…” 2、能用名词做定语的不用动名词做定语，能用形容词做定语的不用名词做定语。 例如：用measurement accuracy 不用measuring accuracy ; 用experimental results 不用experiment results 可直接用名词或名词短语作定语的情况下，不用或少用of句型。 例如：用measurement accuracy 不用accuracy of measurement ; 用equipment structure 不用structure of equipment 3、可用动词的情况尽量避免用动词的名词形式； 例如：用Thickness of plastic sheets was measured 不用Measurement of thickness of plastic sheet was made; 4、避免使用一长串形容词或名词来修饰名词。 如应用The pre-stressed concrete beams reinforced with short carbon fiber 代替The short carbon fiber reinforced pre-stressed concrete beams 5、中英文摘要保持基本一致，但中英文有不同的表达方法，不要简单地直译中文摘要。例如，不要用“××are analyzed and studied (discussed)”来直译“分析研究(讨论)”这一中文概念，用“××are analyzed”就可以了。尽量不要使用not only…but also直译中文“不但”…“而且”这一概念，用and就行了。 6、文摘中不得使用特殊字符及由特殊字符组成的数学表达式。对那些已经为大众熟悉的缩写词，如CAD、CPU、laser、NASA、radar等，可以在文中出现。其它缩写词即便是某些领域的常用缩写词，如FEM (有限元法)、MTMD (多重调谐质量阻尼器)等，也不宜采用，而应用全称。 (三) 图名、表名及中、日、韩的参考文献必须 ．．给出英译，要求与(一)、(二)同。