[{"data":[{"time":"1998-08-31T03","sv":{"05":{"13":0,"14":1}}},{"time":"1998-08-31T03","sv":{"05":{"13":0,"14":1}}}]}]

db.collection.aggregate([{$project:{data:{$reduce:{input:"$data",initialValue:[],in:{$concatArrays:["$$value",{$map:{input:{$objectToArray:"$$this.sv"},as:"s",in:{$map:{input:{$objectToArray:"$$s.v"},as:"s1",in:{$arrayToObject:[[{k:{$concat:["$$this.time",":","$$s.k",":","$$s1.k","Z"]},v:"$$s1.v"}]]}}}}}]}}}}},{$project:{data:{$reduce:{input:"$data",initialValue:{},in:{$mergeObjects:["$$value",{$reduce:{input:"$$this",initialValue:{},in:{$mergeObjects:["$$value","$$this"]}}}]}}}}}])