{"id":333,"date":"2021-12-07T11:18:52","date_gmt":"2021-12-07T10:18:52","guid":{"rendered":"https:\/\/project.inria.fr\/tcypher\/?page_id=333"},"modified":"2021-12-07T11:18:52","modified_gmt":"2021-12-07T10:18:52","slug":"machine-failure","status":"publish","type":"page","link":"https:\/\/project.inria.fr\/tcypher\/machine-failure\/","title":{"rendered":"Machine failure"},"content":{"rendered":"

Machine failure.<\/strong> Return the duration between the last maintenance of a machine and its failure before a given date.<\/p>\n

T-Cypher query:<\/h5>\n

LEFT_SLICE<\/strong> 2019-01-01T08:00:00Z<\/p>\n

MATCH <\/strong>(employee) \u2013[m:maintains]-> (machine)<\/p>\n

<-[c:connectsTo]-(s:sensor)<\/p>\n

WHERE <\/strong>s.meas@T AFTER <\/strong>m@T AND <\/strong>s.meas>4<\/p>\n

RETURN <\/strong>ELAPSED_TIME(m@T, <\/b>s.meas@T)<\/p>\n

\n
Cypher query:<\/h5>\n

MATCH (n0:`employee`)-[m:`maintains`]->(n1:`machine`)<-[c:`connectsTo`]-(s:`sensor`), (s)-[:`hasProperty`]->(smeas:`meas`) WHERE (s.tEnd < smeas.tStart AND smeas.value > 4 AND n0.tStart <= 1546329600000 AND n1.tStart <= 1546329600000 AND s.tStart <= 1546329600000 AND m.tStart <= 1546329600000 AND c.tStart <= 1546329600000 AND smeas.tStart <= 1546329600000) RETURN myFunctions.elapsed_time([m.tStart, m.tEnd], [smeas.tStart, smeas.tEnd]) AS `ELAPSED_TIME(m@T,s.meas)`<\/p>\n

\n
Interpretation:<\/h5>\n

The left slice indicates that the time interval of each query variable should start before the given time instant 2019-01-01T08:00:00Z. Now the s.meas@T<\/b> AFTER <\/b>m@T<\/b> filters the measurements that are recorded by the sensor after the occurrence of the relationship i indicating the maitenance of the machine.\u00a0 The machine’s failure translates to s.meas>4 indicating that the recorded value by the sensor exceeds a given threshold value (4 e.g.).\u00a0 Finally, the elapsed time between the maintenance of the machine and its failure is applied to the time intervals of the relationship m@T referring to the maintenance of the machine and the time interval when the value exceeded the threshold.<\/p>\n","protected":false},"excerpt":{"rendered":"

Machine failure. Return the duration between the last maintenance of a machine and its failure before a given date. T-Cypher query: LEFT_SLICE 2019-01-01T08:00:00Z MATCH (employee) \u2013[m:maintains]-> (machine) <-[c:connectsTo]-(s:sensor) WHERE s.meas@T AFTER m@T AND s.meas>4 RETURN ELAPSED_TIME(m@T, s.meas@T) Cypher query: MATCH (n0:`employee`)-[m:`maintains`]->(n1:`machine`)<-[c:`connectsTo`]-(s:`sensor`), (s)-[:`hasProperty`]->(smeas:`meas`) WHERE (s.tEnd < smeas.tStart AND smeas.value > 4\u2026<\/p>\n

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