{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,29]],"date-time":"2026-04-29T15:12:52Z","timestamp":1777475572473,"version":"3.51.4"},"reference-count":35,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2015,3,18]],"date-time":"2015-03-18T00:00:00Z","timestamp":1426636800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>As the number of elderly people has increased worldwide, there has been a surge of research into assistive technologies to provide them with better care by recognizing their normal and abnormal activities. However, existing abnormal activity recognition (AAR) algorithms rarely consider sub-activity relations when recognizing abnormal activities. This paper presents an application of the Hidden State Conditional Random Field (HCRF) method to detect and assess abnormal activities that often occur in elderly persons\u2019 homes. Based on HCRF, this paper designs two AAR algorithms, and validates them by comparing them with a feature vector distance based algorithm in two experiments. The results demonstrate that the proposed algorithms favorably outperform the competitor, especially when abnormal activities have same sensor type and sensor number as normal activities.<\/jats:p>","DOI":"10.3390\/e17031358","type":"journal-article","created":{"date-parts":[[2015,3,18]],"date-time":"2015-03-18T14:09:08Z","timestamp":1426687748000},"page":"1358-1378","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":18,"title":["Hidden State Conditional Random Field for Abnormal Activity Recognition in Smart Homes"],"prefix":"10.3390","volume":"17","author":[{"given":"Yu","family":"Tong","sequence":"first","affiliation":[{"name":"College of Information Science and Technology, Dalian Maritime University, Dalian 116026, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5848-6398","authenticated-orcid":false,"given":"Rong","family":"Chen","sequence":"additional","affiliation":[{"name":"College of Information Science and Technology, Dalian Maritime University, Dalian 116026, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jian","family":"Gao","sequence":"additional","affiliation":[{"name":"College of Information Science and Technology, Dalian Maritime University, Dalian 116026, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2015,3,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1","DOI":"10.2298\/CSIS0701001A","article-title":"Ambient intelligence: Concepts and applications","volume":"4","author":"Augusto","year":"2007","journal-title":"Comput. 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