{"id":"https://openalex.org/W7157911035","doi":"https://doi.org/10.48550/arxiv.2604.25435","title":"PI-TTA: Physics-Informed Source-Free Test-Time Adaptation for Robust Human Activity Recognition on Mobile Devices","display_name":"PI-TTA: Physics-Informed Source-Free Test-Time Adaptation for Robust Human Activity Recognition on Mobile Devices","publication_year":2026,"publication_date":"2026-04-28","ids":{"openalex":"https://openalex.org/W7157911035","doi":"https://doi.org/10.48550/arxiv.2604.25435"},"language":null,"primary_location":{"id":"doi:10.48550/arxiv.2604.25435","is_oa":true,"landing_page_url":"https://doi.org/10.48550/arxiv.2604.25435","pdf_url":null,"source":{"id":"https://openalex.org/S4306400194","display_name":"arXiv (Cornell University)","issn_l":null,"issn":null,"is_oa":true,"is_in_doaj":false,"is_core":false,"host_organization":"https://openalex.org/I205783295","host_organization_name":"Cornell University","host_organization_lineage":["https://openalex.org/I205783295"],"host_organization_lineage_names":[],"type":"repository"},"license":null,"license_id":null,"version":null,"is_accepted":false,"is_published":false,"raw_source_name":null,"raw_type":"article"},"type":"preprint","indexed_in":["datacite"],"open_access":{"is_oa":true,"oa_status":"green","oa_url":"https://doi.org/10.48550/arxiv.2604.25435","any_repository_has_fulltext":true},"authorships":[{"author_position":"first","author":{"id":"https://openalex.org/A5134856317","display_name":"Changyu Li","orcid":null},"institutions":[],"countries":[],"is_corresponding":true,"raw_author_name":"Li, Changyu","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":"https://openalex.org/A5134849783","display_name":"Lu Wang","orcid":null},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Wang, Lu","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":"https://openalex.org/A5126007061","display_name":"Ming Lei","orcid":null},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Lei, Ming","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":"https://openalex.org/A5134849244","display_name":"Jiashen Liu","orcid":null},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Liu, Jiashen","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":"https://openalex.org/A5134843963","display_name":"Yichen Zhang","orcid":null},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Zhang, Yichen","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":"https://openalex.org/A5134872554","display_name":"Kaishun Wu","orcid":null},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Wu, Kaishun","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"last","author":{"id":"https://openalex.org/A5134842007","display_name":"Fei Luo","orcid":null},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Luo, Fei","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]}],"institutions":[],"countries_distinct_count":0,"institutions_distinct_count":7,"corresponding_author_ids":["https://openalex.org/A5134856317"],"corresponding_institution_ids":[],"apc_list":null,"apc_paid":null,"fwci":null,"has_fulltext":false,"cited_by_count":0,"citation_normalized_percentile":null,"cited_by_percentile_year":null,"biblio":{"volume":null,"issue":null,"first_page":null,"last_page":null},"is_retracted":false,"is_paratext":false,"is_xpac":false,"primary_topic":{"id":"https://openalex.org/T10444","display_name":"Context-Aware Activity Recognition Systems","score":0.8162999749183655,"subfield":{"id":"https://openalex.org/subfields/1707","display_name":"Computer Vision and Pattern Recognition"},"field":{"id":"https://openalex.org/fields/17","display_name":"Computer Science"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},"topics":[{"id":"https://openalex.org/T10444","display_name":"Context-Aware Activity Recognition Systems","score":0.8162999749183655,"subfield":{"id":"https://openalex.org/subfields/1707","display_name":"Computer Vision and Pattern Recognition"},"field":{"id":"https://openalex.org/fields/17","display_name":"Computer Science"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},{"id":"https://openalex.org/T10812","display_name":"Human Pose and Action Recognition","score":0.08919999748468399,"subfield":{"id":"https://openalex.org/subfields/1707","display_name":"Computer Vision and Pattern Recognition"},"field":{"id":"https://openalex.org/fields/17","display_name":"Computer Science"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},{"id":"https://openalex.org/T10273","display_name":"IoT and Edge/Fog Computing","score":0.0066999997943639755,"subfield":{"id":"https://openalex.org/subfields/1705","display_name":"Computer Networks and Communications"},"field":{"id":"https://openalex.org/fields/17","display_name":"Computer Science"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}}],"keywords":[{"id":"https://openalex.org/keywords/adaptation","display_name":"Adaptation (eye)","score":0.6966000199317932},{"id":"https://openalex.org/keywords/activity-recognition","display_name":"Activity recognition","score":0.5676000118255615},{"id":"https://openalex.org/keywords/mobile-device","display_name":"Mobile device","score":0.5676000118255615},{"id":"https://openalex.org/keywords/wearable-computer","display_name":"Wearable computer","score":0.46459999680519104},{"id":"https://openalex.org/keywords/software-deployment","display_name":"Software deployment","score":0.46000000834465027},{"id":"https://openalex.org/keywords/reliability","display_name":"Reliability (semiconductor)","score":0.43970000743865967},{"id":"https://openalex.org/keywords/representation","display_name":"Representation (politics)","score":0.43470001220703125},{"id":"https://openalex.org/keywords/personalization","display_name":"Personalization","score":0.397599995136261},{"id":"https://openalex.org/keywords/wearable-technology","display_name":"Wearable technology","score":0.3783000111579895}],"concepts":[{"id":"https://openalex.org/C41008148","wikidata":"https://www.wikidata.org/wiki/Q21198","display_name":"Computer science","level":0,"score":0.7189000248908997},{"id":"https://openalex.org/C139807058","wikidata":"https://www.wikidata.org/wiki/Q352374","display_name":"Adaptation (eye)","level":2,"score":0.6966000199317932},{"id":"https://openalex.org/C121687571","wikidata":"https://www.wikidata.org/wiki/Q4677630","display_name":"Activity recognition","level":2,"score":0.5676000118255615},{"id":"https://openalex.org/C186967261","wikidata":"https://www.wikidata.org/wiki/Q5082128","display_name":"Mobile device","level":2,"score":0.5676000118255615},{"id":"https://openalex.org/C150594956","wikidata":"https://www.wikidata.org/wiki/Q1334829","display_name":"Wearable computer","level":2,"score":0.46459999680519104},{"id":"https://openalex.org/C79403827","wikidata":"https://www.wikidata.org/wiki/Q3988","display_name":"Real-time computing","level":1,"score":0.46389999985694885},{"id":"https://openalex.org/C105339364","wikidata":"https://www.wikidata.org/wiki/Q2297740","display_name":"Software deployment","level":2,"score":0.46000000834465027},{"id":"https://openalex.org/C43214815","wikidata":"https://www.wikidata.org/wiki/Q7310987","display_name":"Reliability (semiconductor)","level":3,"score":0.43970000743865967},{"id":"https://openalex.org/C2776359362","wikidata":"https://www.wikidata.org/wiki/Q2145286","display_name":"Representation (politics)","level":3,"score":0.43470001220703125},{"id":"https://openalex.org/C183003079","wikidata":"https://www.wikidata.org/wiki/Q1000371","display_name":"Personalization","level":2,"score":0.397599995136261},{"id":"https://openalex.org/C154945302","wikidata":"https://www.wikidata.org/wiki/Q11660","display_name":"Artificial intelligence","level":1,"score":0.39739999175071716},{"id":"https://openalex.org/C54290928","wikidata":"https://www.wikidata.org/wiki/Q4845080","display_name":"Wearable technology","level":3,"score":0.3783000111579895},{"id":"https://openalex.org/C2778755073","wikidata":"https://www.wikidata.org/wiki/Q10858537","display_name":"Scale (ratio)","level":2,"score":0.37540000677108765},{"id":"https://openalex.org/C26517878","wikidata":"https://www.wikidata.org/wiki/Q228039","display_name":"Key (lock)","level":2,"score":0.37439998984336853},{"id":"https://openalex.org/C2988656282","wikidata":"https://www.wikidata.org/wiki/Q4677630","display_name":"Activity detection","level":2,"score":0.3734999895095825},{"id":"https://openalex.org/C89198739","wikidata":"https://www.wikidata.org/wiki/Q3079880","display_name":"Data stream mining","level":2,"score":0.36390000581741333},{"id":"https://openalex.org/C144543869","wikidata":"https://www.wikidata.org/wiki/Q2738570","display_name":"Mobile computing","level":2,"score":0.35249999165534973},{"id":"https://openalex.org/C79061980","wikidata":"https://www.wikidata.org/wiki/Q941680","display_name":"Inertial measurement unit","level":2,"score":0.3422999978065491},{"id":"https://openalex.org/C2780598303","wikidata":"https://www.wikidata.org/wiki/Q65921492","display_name":"Flexibility (engineering)","level":2,"score":0.3345000147819519},{"id":"https://openalex.org/C124101348","wikidata":"https://www.wikidata.org/wiki/Q172491","display_name":"Data mining","level":1,"score":0.3334999978542328},{"id":"https://openalex.org/C2779679103","wikidata":"https://www.wikidata.org/wiki/Q5251805","display_name":"Degradation (telecommunications)","level":2,"score":0.3246999979019165},{"id":"https://openalex.org/C119857082","wikidata":"https://www.wikidata.org/wiki/Q2539","display_name":"Machine learning","level":1,"score":0.3018999993801117},{"id":"https://openalex.org/C89805583","wikidata":"https://www.wikidata.org/wiki/Q192940","display_name":"Accelerometer","level":2,"score":0.2973000109195709},{"id":"https://openalex.org/C120314980","wikidata":"https://www.wikidata.org/wiki/Q180634","display_name":"Distributed computing","level":1,"score":0.29260000586509705},{"id":"https://openalex.org/C48044578","wikidata":"https://www.wikidata.org/wiki/Q727490","display_name":"Scalability","level":2,"score":0.28940001130104065},{"id":"https://openalex.org/C107457646","wikidata":"https://www.wikidata.org/wiki/Q207434","display_name":"Human\u2013computer interaction","level":1,"score":0.27810001373291016},{"id":"https://openalex.org/C63479239","wikidata":"https://www.wikidata.org/wiki/Q7353546","display_name":"Robustness (evolution)","level":3,"score":0.273499995470047},{"id":"https://openalex.org/C95491727","wikidata":"https://www.wikidata.org/wiki/Q992968","display_name":"Mobile telephony","level":3,"score":0.271699994802475},{"id":"https://openalex.org/C82876162","wikidata":"https://www.wikidata.org/wiki/Q17096504","display_name":"Latency (audio)","level":2,"score":0.2549999952316284},{"id":"https://openalex.org/C2779585090","wikidata":"https://www.wikidata.org/wiki/Q3457762","display_name":"Resilience (materials science)","level":2,"score":0.25450000166893005}],"mesh":[],"locations_count":1,"locations":[{"id":"doi:10.48550/arxiv.2604.25435","is_oa":true,"landing_page_url":"https://doi.org/10.48550/arxiv.2604.25435","pdf_url":null,"source":{"id":"https://openalex.org/S4306400194","display_name":"arXiv (Cornell University)","issn_l":null,"issn":null,"is_oa":true,"is_in_doaj":false,"is_core":false,"host_organization":"https://openalex.org/I205783295","host_organization_name":"Cornell University","host_organization_lineage":["https://openalex.org/I205783295"],"host_organization_lineage_names":[],"type":"repository"},"license":null,"license_id":null,"version":null,"is_accepted":false,"is_published":null,"raw_source_name":null,"raw_type":"article"}],"best_oa_location":{"id":"doi:10.48550/arxiv.2604.25435","is_oa":true,"landing_page_url":"https://doi.org/10.48550/arxiv.2604.25435","pdf_url":null,"source":{"id":"https://openalex.org/S4306400194","display_name":"arXiv (Cornell University)","issn_l":null,"issn":null,"is_oa":true,"is_in_doaj":false,"is_core":false,"host_organization":"https://openalex.org/I205783295","host_organization_name":"Cornell University","host_organization_lineage":["https://openalex.org/I205783295"],"host_organization_lineage_names":[],"type":"repository"},"license":null,"license_id":null,"version":null,"is_accepted":false,"is_published":false,"raw_source_name":null,"raw_type":"article"},"sustainable_development_goals":[{"display_name":"Peace, Justice and strong institutions","id":"https://metadata.un.org/sdg/16","score":0.4167467951774597}],"awards":[],"funders":[],"has_content":{"grobid_xml":false,"pdf":false},"content_urls":null,"referenced_works_count":0,"referenced_works":[],"related_works":[],"abstract_inverted_index":{"Source-free":[0],"test-time":[1],"adaptation":[2,88,156,189],"(TTA)":[3],"is":[4],"appealing":[5],"for":[6,125,197],"mobile":[7,199],"and":[8,46,57,79,103,117,132,138,153,169,176,181,194],"wearable":[9],"sensing":[10,200],"because":[11],"it":[12,123],"enables":[13],"on-device":[14,126],"personalization":[15],"from":[16],"unlabeled":[17],"test":[18],"streams":[19,42],"without":[20],"centralizing":[21],"private":[22],"data.":[23],"However,":[24],"sensor-based":[25],"human":[26],"activity":[27],"recognition":[28],"(HAR)":[29],"poses":[30],"challenges":[31],"that":[32,90,143,187],"are":[33,43],"less":[34],"pronounced":[35],"in":[36,150],"standard":[37],"vision":[38],"benchmarks:":[39],"behavioral":[40],"inertial":[41],"temporally":[44],"correlated":[45],"often":[47],"exhibit":[48],"within-session":[49],"shifts":[50],"caused":[51],"by":[52,165,173],"sensor":[53],"rotation,":[54],"placement":[55],"change,":[56],"sampling-rate":[58],"drift.":[59],"Under":[60],"this":[61],"streaming":[62,159],"non-i.i.d.":[63],"setting,":[64],"widely":[65],"used":[66],"vision-style":[67],"TTA":[68],"objectives":[69],"can":[70,190],"become":[71],"unstable,":[72],"leading":[73],"to":[74,167],"overconfident":[75],"errors,":[76],"representation":[77],"collapse,":[78],"catastrophic":[80],"forgetting.":[81],"We":[82],"propose":[83],"PI-TTA,":[84],"a":[85],"lightweight":[86],"source-free":[87,115],"framework":[89],"stabilizes":[91],"online":[92],"updates":[93,107],"through":[94],"three":[95],"physics-consistent":[96],"constraints:":[97],"gravity":[98],"consistency,":[99],"short-horizon":[100],"temporal":[101],"continuity,":[102],"spectral":[104],"stability.":[105],"PI-TTA":[106,144],"the":[108,146],"same":[109],"small":[110],"parameter":[111],"subset":[112],"as":[113],"strong":[114],"baselines":[116,152],"incurs":[118],"only":[119],"modest":[120],"overhead,":[121],"making":[122],"suitable":[124],"deployment.":[127],"Experiments":[128],"on":[129,178],"USCHAD,":[130,179],"PAMAP2,":[131,180],"mHealth":[133],"under":[134,157],"long-sequence":[135,163],"stress":[136],"tests":[137],"factorized":[139],"shift":[140],"protocols":[141],"show":[142],"mitigates":[145],"severe":[147],"degradation":[148],"observed":[149],"confidence-driven":[151],"preserves":[154],"stable":[155],"sustained":[158],"conditions.":[160],"It":[161],"improves":[162],"accuracy":[164],"up":[166],"9.13%":[168],"reduces":[170],"physical-violation":[171],"rates":[172],"27.5%,":[174],"24.1%,":[175],"45.4%":[177],"mHealth,":[182],"respectively.":[183],"These":[184],"results":[185],"demonstrate":[186],"physics-informed":[188],"improve":[191],"accuracy,":[192],"stability,":[193],"deployment":[195],"reliability":[196],"real-world":[198],"systems.":[201]},"counts_by_year":[],"updated_date":"2026-04-30T06:11:10.768123","created_date":"2026-04-30T00:00:00"}