1. 对于一般的涡流检测，检测深度与检测灵敏度总是不能兼得，加大激励信号的频率，检

测灵敏度是加大了，但是渗透深度就减小了。

2. 根据傅里叶级数变换原理，脉冲可以分解成多种频率的信号之和，所以能二者兼得，从

而脉冲涡流检测技术得到了很大的重视。

3. 由于材料磁导率非线性特点的存在， 加大激励电流并不一定能提高检测灵敏度。

4. 磁导率 英文名称：magnetic permeability 表征磁介质磁性的物理量。表示在空间或在

磁芯空间中的线圈流过电流后、产生磁通的阻力、或者是其在磁场中导通磁力线的能力、其公式u=B/H 、其中H=磁场强度、B=磁感应强度，常用符号μ表示，μ为介质的磁导率，或称绝对磁导率

5. 单位正点磁荷在磁场中所受的力被称为磁场强度H。

6. 实际检测过程中， 激励电流的大小将直接影响检测效果， 因此， 将相对磁导率视为

常数进行仿真分析， 必将带来较大分析误差。为此， 在磁导率非线性条件下， 针对不同激励电流对接收线圈中感应电动势的衰减情况， 以及对油套管检测效果的影响进行仿真研究是十分必要的。

7. 解 决 带 包 覆 层 钢 腐 蚀 检 测 的 技 术 难 题 ，根 据 脉 冲 涡 流 检 测 原

理 ，研 制 出 一 套 脉 冲 涡流 钢 腐 蚀 检 测 仪 。

第二篇：论文结论

This paper focuses on the comparative analysis of Obama’s inaugural address and his commencement speech at Barnard College from the perspective of three metafunctions in Systemic-Functional Grammar to explore how Obama adjusts his language to meet the theme of these two speeches and his different intentions in these two speeches.

The addresser of these two speeches in the same: President Barack Obama. The background, the audience, the aims of the speaker and the relationship of the speaker with the audience differ in these two speeches. The audience in the inaugural address is the American people or people all over the world who watch his address through TV or radio. In this inaugural address, Obama aims to get trust and support of American people and convince them that his government can lead them out of the economic crisis. The audience in the commencement speech at Barnard College is the graduating students. In this speech, Obama aims to encourage them to bravely face the future and shoulder their responsibilities. As the themes of these two speeches differ, Obama adopts language features to meet his according aims in these two speeches, which can be revealed in the three matafunctions of these two speeches. The following is a summary of the analysis of these two speeches.

Ideational function is mainly realized by transitivity system and voice system. Transitivity system is made up of six processes-material process, relational process, mental process, behavioral process, verbal process, and existential process. In these two speeches, material process, mental process and relational process play a dominant role, of which material process takes the highest proportion, which reveals the objectivity of political speeches and shows the vigor and vitality of the speaker. The different sequence of six processes reveals different choice of words Obama explores to meet his different aims in these two speeches. In the voice system, more passive voice is adopted in the inaugural address than in the commencement speech, which reflects Obama’s hidden intentions in the inaugural address.

Interpersonal function is mainly realized by mood system, modality system and personal pronouns. In the mood system, declarative mood, which is mainly used to give information, plays a dominant role in these two speeches. There also appears imperatives in these two speeches which attract the audience’s attention and shows Obama’s authoritative position while no interrogatives appear in the inaugural address. In the inaugural address, Obama uses a lot of “let’s-structures” to mitigate power and establishes a kind relationship with the audience while in the commencement speech, Obama uses imperatives more directly to call for the actions of the students. In the modality system, Obama uses more modal operators with median and low value in the inaugural address, which shows his willing and ability but in the commencement speech, modal operators with median and high value are adopted, which strengthens the persuasive function of the speech. As the audience and the aims Obama wants to achieve are different, Obama in these two speeches adopt different sequence of personal pronouns. In the inaugural address, the first plural personal pronoun occurs most frequently, while in the commencement speech, the second personal pronoun and the first person singular pronoun play a dominant role.

Textual function is mainly realized by thematic system, thematic progression and cohesive devices. In the thematic system, the percentage of unmarked themes is higher than that of marked themes in these two speeches, but in the inaugural address, more marked themes are used than in the commencement speech. In thematic progression, simple linear progression is most frequently used in these two speeches, but the sequence of five thematic progression patterns is different. In cohesive system, various cohesive devices including grammatical operators and lexical operators

are adopted that make these two speeches logically and coherently linked.

To summarize, Obama give these two speeches with different audience, with different background and with different aims. He adopts different language features to meet the theme of these two speeches and his different intentions. It can be concluded that language is a system of choices among which language users should make to meet the function of language and the intentions of language users.

Based on the comparative study of Obama’s inaugural address and his commencement speech at Barnard College, some implications are presented in the following.

Firstly, Systemic-Functional Grammar presents a functional approach to study language features, which helps the audience better understand the theme of the discourse and grasp the intentions of the speaker. Besides, Systemic-Functional Grammar gives a clear explanation of the close relationship between language and context, which aids in cultivating cultivating the cultural awareness of the audience.

In addition, this thesis throws lights on language teaching. In language teaching, teachers can help students analyze the connection of the features of a discourse and the theme of the discourse, provide related background information and direct the students to analyze the discourse in a certain context. Besides, teachers can cultivate students’ cultural awareness of the target language.

Although a relatively detailed comparative analysis is conducted in this thesis, some limitations still exist. Firstly, because of time and space, the analysis is only limited to two speeches, the amount of which is not enough. Secondly, in interpersonal function, there is no discussion of modal adjuncts in modality system and tense is excluded in interpersonal function. Some improvements should be made to make this thesis more convincing.