As an AI language model, I do not have access to the specific database or website where research articles on ETPU machines are located. However, in general, research articles on ETPU machines can be found through various sources such as academic journals, conferences, and online databases.

Academic journals such as "Journal of Engineering and Technology for Process Utilization (ETPU)" may publish research articles related to ETPU machines. These journals often require authors to submit their work for review before publication, which can take several months.

Conferences and workshops organized by organizations that focus on process utilization technology (PTT) can also provide opportunities to present and discuss research findings related to ETPU machines. These events typically attract experts in the field and offer a platform for sharing knowledge and ideas.

Online databases such as Google Scholar, PubMed, and Scopus can also be used to search for research articles on ETPU machines. These databases allow users to search for keywords, authors, institutions, and other criteria to find relevant results.

In conclusion, research articles on ETPU machines can be found through academic journals, conferences, and online databases. It is recommended to check with the specific journal's guidelines and requirements to ensure compliance before submitting your article.