During Nielsen's tenure at Kirkwood, enrollment grew to more than 15,000, and the institution was continually recognized as a leading community college in the nation. Nielsen also proved to be instrumental in creating a partnership with Mount Mercy to ease accessibility for transfer students who wished to continue their education.
Nielsen has earned numerous awards and distinctions for his work in the educational community. In 1995 he received the Iowa State University's Laureate Award for prestigious service, education leadership and personal commitment to the teaching profession. He is also the recipient of the Henry Olson Distinguished Service Award. In 2001, the Association of Community College Trustees named Dr. Nielsen as the Central Region Chief Executive Officer and honored him with the Mary Y. Martin Chief Executive Officer of the Year award, which is the nation's most prestigious national community leadership award for Innovation in the Community College.
On the state and national levels, Nielsen has participated as a board member of Iowa Economic Development, Workforce Development Council, Iowa Student Loan Corporation (president), Iowa Association of Community College Presidents, American Association of Community Colleges, League for Innovation in the Community College (past president), and Community College for International Development. Nielsen also serves on the Executive Advisory Board of CampusWorks, a higher education IT evaluation firm.
Nielsen holds advanced degrees from Iowa State University and the University of Iowa.