1 Introduction

The introduction of an English research paper is the core of academic English teaching and research, and its structure and function have received widespread attention. Research typically analyzes introductions from the perspectives of discourse structure, meta discourse, or language features. The CARS model is a pioneering work in introduction analysis, describing the three main language steps of the introduction. Subsequent research explored the differences in language steps and levels of introductions across different disciplines, as well as the meta discourse functions and language features. This study focuses on the field of materials science, using a large amount of text and multiple feature types for multidimensional and cluster analysis, aiming to reveal the communicative function and knowledge construction methods of introductions.

2 Multidimensional Analysis Methods

The Multidimensional Analysis (MDA) method was proposed by Biber (1988) to study the intrinsic variation of oral and written language styles. This method reveals the relativity and multidimensionality of linguistic variation by integrating multiple language features. MDA combines quantitative and qualitative analysis to reveal the dynamic relationship between language features, communicative functions, and language styles. This method has been widely applied to explore more detailed linguistic variations, with an increasing number and types of language features being examined. MDA has expanded to include synchronic comparison and diachronic evolution of oral and written language styles, as well as internal differences in academic discourse, business discourse, research paper chapters, and other language styles. The language features have expanded from 67 to over 150 and 163. This study is based on previous literature and constructs over 160 features and their automatic extraction methods covering vocabulary grammar, phrases, syntax, semantics, and pragmatics, in order to comprehensively examine the multidimensional characteristics of the research paper introduction.

3. Research corpus and methods

Introduced the sources and analysis methods of the research corpus. The corpus comes from the Materials Science sub library of the Academic English Corpus of Beijing Foreign Studies University, which includes 3105 research paper introductions with a total word count of 2275846. The analysis methods include multidimensional analysis, cluster analysis, etc., aiming to explore the language features and communicative functions of the introduction. The specific steps include: using the CLAWS tool to assign part of speech codes, extracting language features and standardizing them, filtering features through R scripts, conducting factor analysis and cluster analysis, and ultimately summarizing the communicative function of the introduction.

4 Results and Discussion

Factor analysis reveals four main communicative functional dimensions in the introduction section of English research papers, each of which is associated with specific language features. These dimensions include "evaluative stance" and "clear reference", "interpretation of knowledge concepts" and "description of process steps", "expansion of epistemic modality", and "overview of specific research". In the dimensions of "evaluative stance" and "clear reference", positive load features such as attributive adjectives, enhancers, attitude adverbs, and non factual adverbs that evaluate or express emotions highlight the evaluative stance, while load features such as participle phrases as postpositive modifiers and prepositional phrases highlight the clarity of reference. In the dimensions of "knowledge concept interpretation" and "process step description", present tense, first person pronoun, and that relative clause are used to interpret knowledge concepts, while passive and past tense are used to describe the research process. The dimension of "expanding the understanding of modal meaning" is mainly expressed through the use of "be" as the main verb, predicate adjective, and pronoun "it". The dimension of "summarizing specific research" summarizes specific research through present participle adverbial clauses and past participle adverbial clauses.

5 Conclusion

This study analyzed a large number of English research paper introductions, revealing the language features and communicative functions in the introductions. It was found that the introductions mainly construct knowledge around four functional dimensions: evaluating stance and clarifying reference, interpreting knowledge concepts and describing process steps, expanding understanding modal meanings, and summarizing specific research. Cluster analysis shows that there are two interactive combinations of these dimensions, reflecting different ways of knowledge construction. The research results have enlightening significance for improving the systematic and targeted teaching of academic English and promoting the cultivation of students' academic communication skills.