英文科研论文写作技巧

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英文科研论文写作简介

1. 引言

英文论文写作的前提是有创新研究成果,创新研究成果的关键是选题。“An acceptable primary

scientific publication” must be “the first disclosure”. 科研论文写作常出现的一个误区是:以为好论

文是“写”出来的,只要会写,论文总能被接受发表。其实,论文被发表只是结果,这个结果是和一系列科研环节密切相关的,论文写作只是其最后一个环节。在选择科研课题和工作切入点时,就需特别注意,一定要有创新内容,科学研究的灵魂是创新,重复别人的工作,从科研的角度来说,是没有意义的。值得注意的是,阅读有关英文科技论文,不仅可以了解研究进展和动态,而且,可以学会科技英文表达。同样,选题很好,研究工作做得不够细致、深入,也难有说服力,难以成为有价值的研究工作。由于本书只介绍英文科研论文的写作,不讲如何做研究,因此只介绍有了好的研究成果后如何写成合格的科研文章。

The goal of scientific research is publication. Scientists, starting as graduate students, are measured primarily not by their dexterity in laboratory manipulations, not by their innate knowledge of either broad or narrow scientific subjects, and certainly not by their wit or charm; they are measured, and become known (or remain unknown) by their publications.

A scientific experiment, no matter how spectacular the results, is not completed until the results are published.

Thus, the scientists must not only “do” the science but must “write” science. Bad writing can and often does prevent or delay the publication of good science.

2. 科研论文的一般格式。

科研论文,不象散文、小说那样形式可以千姿百态,而具有较为固定的格式。从某种意义上说,科研论文是“八股文”。

The IMRAD format.

What question (problem) was studied? The answer is the Introduction. How was the problem studied? The answer is the Methods. What were the findings? The answer is the Results. What do these findings mean? The answer is the Discussion.

其通常的组成和每部分的特点见表1。

表1 科研论文格式及其特点 组成部分名称 (按文章顺序) 题目 Title 特点或简要说明 10-20 words 简明,不必求全。 Brief. A complete sentence is not necessary. 作者信息 姓名 通讯作者:往往是固定研究人员或项目负责人。 单位地址 联系方式:E-mail地址、 传真、电话。 Authorship Corresponding author: Faculty member or principal Names of authors Affiliation E-mail address and telephone and fax numbers for corresponding author, if possible. 摘要 Abstract investigator. 150-200 英文词,说明研究目的、方法、结果、结论和意义。可以写一些定量结果。不仅对读者,而且对文献检索者都有帮助。 150-200 words to give purpose, methods or procedures, new results and their significance, and conclusions. Write for literature searchers as well as Journal readers. Include major quantitative data if they can be stated briefly, but do not include background material. 3-5个关键词,作为论文检索用,使读者可用关键词方便检索到此论文,并对论文按内容分类。 3-5 key words which can be regarded as index words. 说明文章中符号表示的量的意义,单位。尽量用国际单位制。 Use SI units as much as possible. 篇幅:全文的10-20 %。 说明所研究问题的重要性;相关研究回顾与综述:指出已有研究的不足和局限,但语气应友善而含蓄。说明本论文的目的和重要性。 Introduce the importance of the problem studied. Review of previous work. State the limitations or shortcomings of the previous work. Clearly state the purpose and significance of the present work. Notice: Do not attempt to survey the literature completely. If a recent article has a survey on the subject, cite that article without repeating its individual citations. In general, the Introduction should be no more than 3 double-spaced word-processed pages with no figures and tables. 篇幅:全文的20-30%。 介绍为简化问题所作的必要且合理的假设; 对问题进行数学描述:列方程、边界条件和初始条件;

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关键词 Key words 符号表 Nomenclature, Notation or Symbols 引言 Introduction 研究或实验方法 Research approach Theoretical section Experimental section 问题求解; 或介绍实验仪器、条件和步骤:使读者阅读后可重复实验。 Make necessary assumptions. or Describe the problem in mathematical equations together with relating boundary and initial conditions. Obtain the solution. Let the research can be reproduced. -Describe the apparatus and instruments. -Describe pertinent and critical factors involved in the experimental work. 结果和讨论 Results and discussion 篇幅:全文的40%左右。 研究结果介绍,数据的必要解释,新发现讨论,与其它相关结果的比较。 结果和讨论也可分开。 结果:直接的发现;讨论:间接的发现。 此部分内容安排要特别注意逻辑性。 Present the results. Discuss new findings. Provide explanations for data. Elucidate models. Compare the results with other related works. Results and Discussion may be separated. Results: direct findings. Discussion: indirect findings. 结论 Conclusions 致谢 Acknowledgements 参考文献 References Notice: please logically arrange the contents. 介绍研究工作的主要结论。力求简明。 Summarize conclusions of the work. 说明本工作受到的资助及得到的帮助。 Information regarding the supporter (s) (e.g., financial support) is included here. 对于一般科研论文,参考文献为10-20篇;对于综述性论文,参考文献为60-100篇。 10-20 references for research paper and 60-100 references for review paper. 一些公式的详细推导等内容可放在附录部分,以便使论文更紧凑。 Some detailed derivation of equations etc. could be placed in this part. 附录 Appendix

以上为英文科技论文的一般要求,不同期刊风格和要求会有所不同。

练习1。

2. 科技论文的写作步骤

步骤及注意事项如同绘画。绘画要构思、画轮廓、再描绘、收拾。科技论文的写作步骤见表2。

表2 英文科技论文写作步骤

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准备材料 确定题目 写提纲 安排和调整材料 写论文草稿 认真检查:内容、炼字、炼句 请指导教师修改

和指导老师讨论。 和指导老师讨论。 在有条件的情况下请Native English speaker 修改英文。 值得注意的是,论文最好在研究工作进行中就开始酝酿,这样对研究本身的完整性会有帮助,而且,写作过程中也往往会发现一些问题,由于实验装置尚在,实验还可进行,这些问题还可方便解决。

练习2。

3. 各部分写作的注意事项 3.0 如何写论文题目

First impressions are strong impressions; a title ought therefore to be well studied, and to give, so far as its limit permit, a definite and concise indication of what is to come.

----T. Cliffort Allburt

What is good title? I define it as the fewest possible words that adequately describe the context of the paper.

3.1 如何写英文摘要

英文摘要是全文的浓缩,一般包括研究目的、研究方法、研究结果和结论。摘要是全文的摘要,因此论文从引言(Introduction)、论文展开(Approach),结果(Results)和讨论(Discussion)以及结论部分的要点在引言中都应有反映。摘要部分应尽可能简明,一般不超过300个词,摘要比论文具有更广泛的读者,因此,尽量用通俗和易懂的词汇(这些词汇无需通过阅读全文或查相关文献后就可明白),且风格、时态等应统一。在英文摘要中,时态可以是一般现在时,一般过去时和现在完成时,具体用何种时态,应根据表达的内容而定,但一般多用被动语态。请看下面的例1-例7。注意,摘要中别忘了写出论文的主要发现或结论。

一般情况下,摘要中不列参考文献,不含图表。英文摘要内容完整,可独立存在。摘要虽在最前面,但实际上,它往往最后写。等全文完成后,再根据全文的内容提炼和推敲。当然,有些国际会议,开始只需要提交摘要,这时,摘要常常先写。

下面列举了几篇国际期刊论文的英文摘要,供读者参考。同时注意缩写字的使用。 摘要例1

Abstract: Interactions between volatile organic compounds (VOCs) and vinyl flooring (VF), a relatively homogenous, diffusion-controlled building material, were characterized. The sorption/desorption behavior of VF was investigated using single-component and binary systems of seven common VOCs ranging in molecular weight from n-butanol to n-pentadecane. The simultaneous sorption of VOCs and water vapor by VF was also investigated. Rapid determination of the material/air partition coefficient (K) and the material-phase diffusion coefficient (D) for each VOC was achieved by placing thin VF slabs in a dynamic microbalance and subjecting them to controlled sorption/desorption cycles. K and D are shown to be independent of concentration for all of the VOCs and water vapor. For the four alkane VOCs studied, K correlates well with vapor pressure and D correlates well with molecular weight, providing a means to estimate these parameters for other alkane VOCs. While the simultaneous sorption of a binary mixture of VOCs is non-competitive, the presence of water vapor increases the uptake of VOCs by VF. This approach can be applied to other diffusion-controlled materials and should facilitate the prediction of their source/sink behavior using physically-based models.

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Keywords: Building material; Emission; Indoor air; Microbalance; Sink; Sorption 摘要例2[2]

Abstract: Desiccant systems have been proposed as energy saving alternatives to vapor compression air

conditioning for handling the latent load. Use of liquid desiccants offers several design and performance advantages over solid desiccants, especially when solar energy is used for regeneration. For liquid-gas contact, packed towers with low pressure drop provide good heat and mass transfer characteristics for compact designs. This paper presents the results from a study of the performance of a packed tower absorber and regenerator for an aqueous lithium chloride desiccant dehumidification system. The rates of dehumidification and regeneration, as well as the effectiveness of the dehumidification and regeneration processes were assessed under the effects of variables such as air and desiccant flow rates, air temperature and humidity, and desiccant temperature and concentration. A variation of the ?berg and Goswami Mathematical model was used to predict the experimental findings giving satisfactory results.

摘要例3[3]

Abstract: This paper presents a performance evaluation of two passive cooling strategies, daytime

ventilation and night cooling, for a generic, six-story suburban apartment building in Beijing and Shanghai. The investigation uses a coupled, transient simulation approach to model heat transfer and airflow in the apartments. Wind-driven ventilation is simulated using computational fluid dynamics (CFD). Occupant thermal comfort is accessed using Fanger?s comfort model. The results show that night cooling is superior to daytime ventilation. Night cooling may replace air-conditioning systems for a significant part of the cooling season in Beijing, but with a high condensation risk. For Shanghai, neither of the two passive cooling strategies can be considered successful.

摘要例4[4]

ABSTRACT: This paper presents the results of a computer program developed for solving 2- and 3-D

ventilation problems. The program solves, in finite difference form, the steady-state conservation equations of mass, momentum and thermal energy. Presentation of the fluctuating velocity components is made using the k-ε turbulence model. Predicted results of air velocity and temperature distribution in a room are corroborated by experimental measurements. The numerical solution is extended to other room ventilation problems of practical interest.

3.2 如何写引言

中国有句俗话:好的开头等于成功的一半。英文中有句名言:“A bad beginning makes a bad ending”。两者表达方式不同,意思却相近:开头对很多事非常重要,对写文章也不例外。引言即是文章的开头。 写作之前,心中需对阅读对象有所了解和估计,这样在行文时对遣词造句就会有把握,既避免过于专业,使读者难以理解,又不致过于平白,让读者索然无味。

引言一般用一般现在时写,如前所述,引言中应介绍以下几方面的内容:

(1) 介绍讨论的问题、介绍研究的背景,说明讨论的范围及解决问题的重要性。读者往往通过浏览

论文题目、摘要、引言、图标和结论决定是否仔细阅读全文。因此,在引言中应开门见山,说明要讨论的问题及其重要性。

(2) 相关研究回顾与综述。对已有研究的评价要实事求是,对前人工作的精彩和可参考之处应简要说明,对已有研究的不足和局限,也应指出,但语气应友善而含蓄。

(3) 说明本研究的目的和特别之处。有了前面2部分的铺垫,现在就要具体说明本研究要解决什么问题,在解决思路、方法、手段等上有什么新颖或改进之处。

(4) 说明一下文章安排。是全部论文的导读。就像领人去一个地方游览或参观,先介绍一下游览的

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活动安排并给一张游览地的地图。在这部分,下面的表述可供参考: This paper is divided into five major sections as follows… Section one of this paper opens with…

Section three develops the second hypothesis on…

Section four shows (introduces, reveals, treats, develops, deals with, etc.)… The result of … is given in the last section. (5) 介绍一下主要结论。

(4) 和 (5) 的安排比较灵活,有时可不同时出现,甚至不出现,只介绍 (3) -本论文的目的或主要贡献及其重要性。

关于引言的功能,Raleigh Nelson有一段形象的介绍:“(it) may be thought of as a preliminary conference in which the writer and prospective reader ?go into a huddle? and agree in advance on the exact limits of the subject, the terms in which to discuss it, the angle from which to approach it, and the plan of treatment that will be most convenient to both.”

引言部分逻辑性很强。首先当然是点出问题,并使读者一下被吸引。这就必须交代为什么你选择该问题,该问题的解决状况如何,还有那些问题需要研究,你如何解决这些问题,得到了哪些有意义的结果。这些环节联系紧密、环环相扣。

引言中要引用已发表的相关文献,一般有两种引出方式:按所引文献出现的先后顺序标注,按所引文献作者的姓名的字母顺序标注。具体方式,视所投期刊要求而定。

下面通过一些例子对上面的介绍加以说明。

例1: INTRODUCTION

A variety of building materials (e.g., adhesives, sealants, paints, stains, carpets, vinyl flooring, and engineered woods) can act as indoor sources of volatile organic compounds (VOCs). Following their installation or application, these materials typically contain residual quantities of VOCs that are then emitted over time. Once installed and depending upon their properties, these materials may also interact with airborne VOCs through alternating sorption and desorption cycles (Zhao et al., 1999b, 2001). Consequently, building materials can have a significant impact on indoor air quality both as sources of and sinks for volatile compounds.

Current methods for characterizing the source/sink behavior of building materials typically involve chamber studies. This approach can b time-consuming and costly, and is subject to several limitations (Little and Hodgson, 1996). For those indoor sources and sinks that are controlled by internal diffusion processes, physically-based diffusion models hold considerable promise for prediction emission characteristics when compared to empirical methods (Cox et al., 2000b, 2001b).

The key parameters for physically-based models are the material/air partition coefficient (K), the material-phase diffusion coefficient (D), and, in the case of a source, the initial concentration of VOC in the material (C0). Rapid and reliable determination of these key parameters by direct measurements or by estimations based on readily available VOC/building material properties should greatly facilitate the development and use of mechanistic models for characterizing the source/sink behavior of diffusion-controlled materials (Zhao et al., 1999a; Cox et al., 2000a, 2001a).

Several procedures have been used to measure D and K of volatile compounds in building materials. D and K have been inferred from experimental data obtained in chamber studies (Little et al., 1994). A procedure using a two-compartment chamber has also been used for D and K measurement. A specimen of building material is installed between the two compartments. A concentration of a particular compound if introduced into the gas-phase of one compartment while the gas-phase concentration in the other compartment is measured over time. D and K are then indirectly estimated from gas-phase concentration data (Bodalal et al., 2000;

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Meininghaus et al., 2000). A complicating feature of this method is that VOC transport between chambers may occur by gas-phase diffusion through pores in the building material in addition to solid-phase Fickian diffusion, confounding estimates of the mass transport characteristics of the solid material.

A procedure based on a European Committee for Standardization (CEN) method has also been used to estimate D. A building material sample is tightly fastened to the open end of a cup containing a liquid VOC. As the VOC diffuses from the saturated gas-phase through the building material sample, cup weight over time is recorded. Weight change data can be used to estimate D. (kirchner et al., 1999). A significant drawback of this method is that D has been shown to become concentration dependent in polymers at concentrations approaching saturation (Park et al., 1989).

In accordance with a previously proposed strategy for characterizing homogeneous, diffusion-controlled, indoor sources and sinks (Little and Hodgson, 1996), the objectives of this study were to (1) develop a simple and rapid experimental method for directly measuring the key equilibrium and kinetic parameters, (2) examine the validity of several primary assumptions upon which the previously mentioned physically-based models are founded and (3) develop correlations between the O and K, and readily available properties of VOCs.

例2[2]: 1. Introduction

Liquid desiccant cooling systems have been proposed as alternatives to the conventional vapor compression cooling systems to control air humidity, especially in hot and humid areas. Research has shown that a liquid desiccant cooling system can reduce the overall energy consumption, as well as shift the energy use away from electricity and toward renewable and cheaper fuels (Oberg and Goswami, 1998a). Burns et al. (1985) found that utilizing desiccant cooling in a supermarket reduced the energy cost of air conditioning by 60% as compared to conventional cooling. Oberg and Goswami (1998a) modeled a hybrid solar cooling system obtaining an electrical energy savings of 80%, and Chengchao and Ketao (1997) showed by computer simulation that solar liquid desiccant air conditioning has advantages over vapor compression air conditioning system in its suitability for hot and humid areas and high air flow rates.

Use of liquid desiccants offers several design and performance advantages over solid desiccants, especially when solar energy is used for regeneration (Oberg and Goswami, 1998c). Several liquid desiccants are commercially available: triethylene glycol, diethylene glycol, ethylene glycol, and brines such as calcium chloride, lithium chloride, lithium bromide, and calcium bromide which are used singly or in combination. The usefulness of a particular liquid desiccant depends upon the application. At the University of Florida, Oberg and Goswami (1998a,b) conducted a study of a hybrid solar liquid desiccant cooling system using triethylene glycol (TEG) as the desiccant. Their experimental work concluded that glycol works well as a desiccant. However, pure triethylene glycol does have a small vapor pressure which causes some of the glycol to evaporate into the air. Although triethylene glycol in nontoxic, any evaporation into the supply air stream makes it unacceptable for use in air conditioning of an occupied building. Therefore, there is a need to evaluate other liquid desiccants for hybrid solar desiccant cooling systems. Lithium chloride (LiCl) is a good candidate material since it has good desiccant characteristics and does not vaporize in air at ambient conditions. A disadvantage with LiCl is that it is corrosive. This paper presents an experimental and theoretical study of aqueous lithium chloride as a desiccant for a solar hybrid cooling system, using a packed bed dehumidifier and regenerator.

A number of experimental studies have been carried out on packed bed dehumidifiers using salt solutions as desiccants. Chung et al. (1992, 1993), and Chen et al. (1989) used lithium chloride (LiCl); Ullah et al. (1998), Kinsara et al. (1998) and Lazzarin et al. (1999) used calcium chloride (CaCl2); while Ahmed et al. (1997) and Patnaik et al. (1990) used lithium bromide (LiBr). Other experiments for absorbers using LiCl were carried out by Kessling et al. (1998), Kim et al. (1997) and Scalabrin and Scaltriti (1990).

The moisture that transfers from the air to the liquid desiccant in the dehumidifier causes a dilution of the

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desiccant resulting in a reduction in its ability to absorb more water. Therefore, the desiccant must bee regenerated to its original concentration. The regeneration process requires heat which can be obtained from a low temperature source, for which solar energy and waste energy from other processes are suitable. Different ways to regenerate liquid desiccants have been proposed. Hollands (1963) presented results from the regeneration of lithium chloride in a solar still. Hollands focused his study on the still efficiency, concluding that lithium chloride can be regenerated in a solar still with a daily efficiency of 5 to 20% depending on the insolation and the concentration of the desiccant. Ahmed Khalid et al. (1998) presented an exergy analysis of a partly closed solar generator to compare it with the solar collector reported previously. Ahmed et al. (1997) simulated a hybrid cycle with a partly closed-open solar regenerator for regeneration the weak solution. They found that the system COP is about 50% higher than that of a conventional vapor absorption machine. Leboeuf and Lof (1980) presented an analysis of a lithium chloride open cycle absorption air conditioner which utilizes a packed bed for regeneration of the desiccant solution driven by solar heated air. In this case, the air temperature ranged from 65 to 96oC while the desiccant temperature ranged from 40 to 55 oC. Lof et al. (1984) conducted experimental and theoretical studies of regeneration of aqueous lithium chloride solution with solar heated air in a packed column. In this case, air at a temperature of 82 to 109 oC was used to regenerate the desiccant at an average temperature of 36 oC.

In any thermodynamic system, the conditions of the working fluids and parameters of the physical equipment define the overall performance of the system. In a liquid desiccant cooling system, variables such as air and desiccant flow rate, air temperature and humidity, desiccant temperature and concentration are of great interest for the performance of the dehumidifier. The mass ratio of air to desiccant solution MR=mair/msol is an important factor for absorber efficiency and system capacity. Previous studies have reported the performance of packed bed absorbers and regenerators with MR between 1.3 and 3.3. The range of MR varies with the type of absorber/regenerator, but in general better results are obtained for small MR.

For simulation purposes, validated models are required for modeling the absorber in a liquid desiccant system. Models using lithium chloride have been descried by Khan and Martinez (1998), Ahmed et al. (1997) and Kavasogullare et al. (1991). Due to the complexity of the dehumidification process, theoretical modeling relies heavily upon experimental data. Oberg and Goswami (1998b) developed a model for a packed bed liquid desiccant air dehumidifier and regenerator with triethylene glycol as liquid desiccant which was validated satisfactorily by the experimental data. The present study uses a modified version of the mathematical model developed by Oberg and Goswami to compare the experimental results of a packed bed dehumidifier and regenerator using lithium chloride as a desiccant.

例3[4]

Introduction

The measure of success of an air conditioning system design is normally assessed by the thermal conditions provided by the system in the occupied zones of a building. Although the thermal condition of the air supply may be finely tuned at the plant to offset the sensible and latent heat loads of the rooms, the thermal condition in the room is ultimately determined by the method of distributing the air into the room. Fanger and Pedersen [1] have shown that the thermal comfort in a room is not only affected by how uniform the air temperature and air velocity are in the occupied zone (the lower part of a room to a height 2m) but also by the turbulence intensity of the air motion and the dominant frequency of the flow fluctuations. There environmental parameters which have profound influence on comfort, are influenced by the method used to diffuse the air into the room. In addition to the supply air velocity and temperature, the size and position of the diffuser in the room have a major influence on the thermal condition in the occupied zone [2].

In air distribution practice, ceilings and walls are very common surfaces which are used for diffusing the air jet so that when this penetrates the occupied zone its velocity would have decayed substantially. Thus the

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occurrence of draughts is minimized. The region between the ceiling and the occupied zone serves as an entrainment region for the jet which causes a decay of the main jet velocity as a result of the increase in the mass flow rate of the jet.

There are sufficient information and design guides [3, 4] which may be applied for predicting room conditions produced by conventional air distribution methods. However, where non-conventional methods of air supply are employed or where surface protrusions or rough surfaces are used in a wall-jet supply, the design data is scarce. The air distribution system designer has to rely on data obtained from a physical model of the proposed air distribution method. Modifications to these models are then made until the desired conditions are achieved. Apart from being costly and time consuming, physical models are not always possible to construct at full scale. Air distribution studies for the design of atria, theatres, indoor stadiums etc. can only be feasibly conducted with reduced scale models. However, tests carried out in a model should be made with dynamic and thermal similarity if they are to be directly applied to the full scale. This normally requires the equality of the Reynolds number, Re, and the Archimedes number, Ar, [5, 6] which is not possible to achieve in the model concurrently.

The other problem which is often encountered in air distribution design is the interference to the jet from rough surfaces and surface-mounted obstacles such as structural beams, light fittings etc. Previous studies [7, 8] have shown that surface-mounted obstacles cause a faster decay of the jet velocity and when the distance of an obstacle from the air supply is less than a certain value called “the critical distance”, a deflection of the jet into the occupied zone takes place. This phenomenon renders the air distribution in the room ineffective in removing the heat load and, as a result, the thermal comfort in the occupied zone deteriorates. Here again there is a scarcity of design data, particularly for non-isothermal air jets.

Air distribution problems, such as those discussed here, are most suitable for numerical solutions which, by their nature, are good design optimization tools. Since most air distribution methods are unique to a particular building a rule of thumb approach is not often a good design practice. For this reason, a mock-up evaluation has so far been the safest design procedure. Therefore, numerical solutions are most suitable for air distribution system design as results can b readily obtained and modifications can be made as required within a short space of time. Because of the complexity of the air flow and heat transfer processes in a room, the numerical solutions to these flow problems use iterative procedures that require large computing time and memory. Therefore, rigorous validation of these solutions is needed before they can be applied to wide ranging air distribution problems.

In this paper a review is given of published work on numerical solutions as applied to room ventilation. The finite volume solution procedure which has been widely used in the past is briefly described and the equations used in the k-ε turbulence model are presented. Numerical solutions are given for two- and three-dimensional flows and, where possible, comparison is made with experimental data. The boundary conditions used in these solutions are also described.

3.3 如何写论文的展开部分(Approach), 结果和讨论(Results and Discussion)

3.3.1 材料和方法部分

对于以实验为主的研究论文,该部分往往位于论文展开部分的前面。

对于实验,描述应尽可能详细。详细的程度应使别的研究者可以重复你的实验,对难以重复的实验可评价你的实验。

这一部分经常采用小标题,如:subjects, apparatus, experimental design, and chemical synthesis。 在这一部分,你应当说明:(1) 你所用的材料和化学药品的名称;(2)实验条件;(3)实验仪器;(4)实验方法和步骤。

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3.3.2 原理和理论模型部分

对于理论分析和数值计算为主的研究论文,该部分往往位于论文展开部分的前面。

一般首先用数学方法描述所讨论的问题,如列出控制方程、边界条件和初始条件。为简化问题并突出问题本质,常需对问题进行合理假设。这部分会引入一些方程、格式、边界条件和初始条件,下面通过一些例子说明其经常采用的表达方式。

例1[5]

DEVELOPMENT OF MODEL

The model assumes that VOCs are emitted out of a single uniform layer of material slab with VOC-impermeable backing material, and a schematic of the idealized building material slab placed in atmosphere is shown in Fig.1. The governing equation describing the transient diffusion through the slab is

?C(x,t)?t?D?C(x,t)?x22 (1)

where C(x,t) is the concentration of the contaminant in the building material slab, t is time, and x is the linear distance. For given contaminant, the mass diffusion coefficient D is assumed to be constant. The initial condition assumes that the compound of interest is uniformly distributed throughout the building material slab, i.e.,

C(x,t)?C0for0?x?L, t=0 (2)

where L is the thickness of the slab, and C0 is the initial contaminant concentration. Since the slab is resting on a VOC-impermeable surface, the boundary condition of the lower surface of the slab is

?C(x,t)?t?0,t?0,x?0 (3)

A third boundary condition is imposed on the upper surface of the slab (Fig.1)

?D?C(x,t)?x?hm(Cs(t)?C?(t)),t?0,x?L. (4)

where hm is the convective mass transfer coefficient, m/s;Cs(t) is the concentration of VOC in the air adjacent to the interface; mg m-3; C?(t) is the VOC concentration in atmosphere, mg m-3. It should be mentioned that almost all the physically based models in the literature assumed Cs(t)= C?(t), i.e. implied that hm is infinite, (Dunn, 1987; Clausen et al., 1991; Little et al., 1994). Obviously, the case assumed is a special case of equation (4). Besides, equilibrium exists between the contaminant concentrations in the surface layer of the slab and the ambient air, or (Little et al., 1994)

C(x,t)?KCs(t),t?0,x?L. (5)

where K is the so-called partition coefficient.

x C?(t) Cs(t) C(L,t) C(x,t) building material ?m(t)air interface L

9

Fig.1 Schematic shown of a building material slab in atmosphere.

The solutions to equations (1)-(5) derived by us are as follows

where H?hmKD?C(x,t) ?(t ) ?? ?cos(?x)? KC ? ? 2 2 m (6)

?L(??H)?Hm?1mmsin(?mL)2(?m?H)22[(C0?KC?(0))e?D?mt2??t0e?D?m(t??)2?KdC?(?)], βm (m=1,2,…) are the positive roots of

?m?tan(?mL)?H (7)

Equation (6) gives the contaminant concentration in the building material slab as a function of distance from the base of the slab, and also of time.

?Thus, VOC emission rate per unit area at instant t m(t) and VOC mass emitted from per unit area of the building material slab before instant t m(t) can be respectively expressed as follows

?m(t)??D??C(x,t)?xx?L??D??sin(?mL)?m?122(?m?H)L(?2m22?H)?H2?

[(C0?KC?(0))em(t)???D?0t?D?mt2??t0t0e??D?m(t??)2?KdC?(?)] (8)

2(?m?H)22?C(x,t)?x?D?mt2x?Ldt?D?t?sinm?12(?mL)?L(?2m?H)?H2?

[(C0?KC?(0))e??0e?D?m(t??)2?KdC?(?)] dt (9)

下面是引出公式的一些例句、句型: Plugging these values into.... It yields following inequality:

From Eqs. (1), (2) and (5) it follows that A may be expressed as

Equation (1) relates A and B.

Then the solution to equation (1) is

Combining equations (1) and (2) gives

Using the boundary conditions (3) and (4), eq.(1) can be written as:

Considering the boundary conditions (3), (4) and (5), the temperature distribution is:

Assuming a relationship between A and B of the form

Expression (1) is applicable only for angles from 0 to θ, whereθsatisfies the condition …

Assuming steady-state conditions, governing equations are: …

这里需要注意的是,对公式中出现的符号有两种解释方式,其一是在公式下,用where引出解释,其二是在论文中(一般在引言前)用符号表(Nomenclature , Notation, Symbols)说明。 一般当符号比较多时采用后者。需注意的是一旦采用后者,公式中出现的符号可不再解释,避免重复。后者的例子如下:

例1[2]

Nomenclature

10

?t specific surface area of packing (m/m)

23

?w wetted surface area of packing (m/m)

cp specific heat (kJ/kg C)

o

23

D diffusivity (m/s)

Dp nominal size of packing (m)

2

FG gas phase mass transfer coefficient (kmol/m s)

2

FL liquid phase mass transfer coefficient (kmol/m s) G superficial air (gas) flow rate (kg/m s)

2

2

2

g acceleration of gravity (m/s)

hG gas side heat transfer coefficient (kJ/m s) kG gas phase mass transfer coefficient (kmol/m s Pa)

2

2

kL liquid phase mass transfer coefficient (m/s) L superficial desiccant flow rate (kg/m s) LiCl lithium chloride

2

M molar mass (kg/kmol) m flow rate (g/s) or (kg/s)

P total pressure (Pa) Pr Prandtl number pv vapor pressure (Pa) Sc Schmidt number

T temperature (C)

o

X desiccant concentration (kgLiCl/kgsolution) x desiccant mole fraction (kmolLiCl/kmolsolution)

xSM logarithmic mean solvent mole fraction difference between the bulk liquid and interface values

(kmolLiCl/kmolsolution)

Y air humidity ration (kg water/kg dry air) y water mole fraction (kmol water/kmol air)

Z tower height (m)

Greek letters

? surface tension (N/m) ? effectiveness

? latent heat of condensation (kJ/kg)

2

? viscosity (N/m)

? density (kg/m)

11

3

Subscripts A air

C critical

cond water condensation equ equivalent

evap water evaporation G gas phase IN inlet i interface

L desiccant or liquid phase OUT outlet

o reference state

12

例2

NOTATION

A emission area of building material (m2)

-3

C concentration of compound in building material (mg m)

C0(x) initial concentration of compound in building material (mg m-3) Cs(t) concentration of compound in the air adjacent to the interface (mg m-3) C?(t) concentration of compound in atmosphere or in chamber (mg m) D mass diffusion coefficient for compound in building material (m2 s-1) hm convective mass transfer coefficient (m/s)

K partition coefficient between building material and air (dimensionless) L thickness of building material slab (m)

M total mass per unit area of VOC emitted from building material (mg m-2) m(t) total mass per unit area of VOC emitted from building material before time

t (mg m-2)

?[6]

-3

m(t) emission rate per unit area of VOC from building material at time t

(mg m-2s-1)

PB particleboard

3-1

Q volumetric air flow rate through chamber (m s) t time (s)

tc the critical time (h)

TVOC total volatile organic compound V volume of air in chamber (m3) VOC volatile organic compound x linear distance (m)

3.3.3 结果和讨论部分

研究的发现和结果根据其性质不同,有不同的英文表述:Results, experimental results, experimental observations, computer results, numerical results, solutions 和results of analysis。研究结果往往用图表表示。

下面的例子说明如何在文中引出图表。

(1) The size and shape of the asci, ascospores and conidia from all specimens examined (Table 1) were essentially identical.

(2) The calculated 37GHz (horizontal polarization) brightness temperatures for dry snow over frozen grounds (Fig.8) show the effect of the changing thickness of the depth of the hoar layer.

(3) Figure 2 shows the relationship between A and B. (4) Curve A in Figure 4 illustrates equation (1).

(5) Table 1 summarizes property data for altitudes to 10,000m. (6) The principle of the method may be easily followed from Figure 6. (7) … is sketched in Fig.1.

(8) … is depicted in Fig.2.

描述观测、测试和实验时,常用一般过去时;讨论数据、图和表时,常用一般现在时。 Results部分一般介绍的是显而易见的结论;Discussion部分介绍的是并不显而易见但通

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过分析和推理可得出的结论,可以对结果进行检验、比较、解释和分析等,并说明结果的意义。

下述表达在该部分会经常使用:

it seems note that it is noted that it appears that this indicates it suggests that it shows that it provides that it gives that it presents that it summarizes that it illustrates that it reveals that it displays that it displays that it demonstrates that 上述动词英文中称为Indicative or Informative Verbs。 例句:

Table 5 shows the most common modes of infection.

Table 5 shows that the most common source of infection is disks brought from home. Table 5 provides infection-source percentages.

Inspection of this equation shows that...

The study consists of three parts. The first deals with ..., and shows that.... The second part covers..., and concludes that.... The third part treats with the ..., and demonstrates that....

在结果和讨论表达中,As 从句也经常被使用。

As shown in Table 5, home disks are the most frequent sources of infection. As can be seen in Fig.8, infant mortality is still high in urban areas. 此外,还需注意动词后介词的使用:

As revealed by the graph, the defect rate has declined. As can be seen from the data in Tab.1, …

As shown by the data in Tab.1, … As described on page 24, …

注意,这里的As 从句中一般采用被动语态,从句中无主语! 练习4。

表示计算或理论分析结果与实验结果相符时,经常采用以下表达: agree well with, be validate with, be in agreement with, compared favorably with 例句:

(1) The analytical results compared favorably with the numerical solution.

(2) A closed-form solution, which could be obtained via a theoretical analysis of the melting

process, shows excellent agreement with the experimental results.

3.3.4 结论部分

结论部分是全文的重要部分,反映了全文的主要发现和结论,表述力求简明。下面是一些例子。

例1[1]: Conclusions

The gravimetric method for directly measuring K and D in VF is simple and effective and can be applied to other indoor materials that can be accommodated in a microbalance. For the compounds and concentration ranges studied, K and D do not depend on concentration. This concentration independence should hold at the lower concentrations typically associated with gas and material-phases in the indoor environment, confirming two of the key assumptions on which the previously developed source/sink diffusion models are based (Little et al., 1994; Little and Hodgsom, 1996; Cox et al., 2000b, 2001b). the observed partition and diffusion coefficients for a

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