apsis-book/content/flows/time-scale-conversion.json

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{
"id": "time-scale-conversion",
"title": "Time scale conversion",
"summary": "How an instant enters the model, is stored on one uniform scale, and is read back on any supported scale.",
"nodes": [
{
"id": "input",
"label": "Calendar fields or an MJD, with a scale",
"kind": "data",
"group": "input",
"summary": "The caller states which scale the number is on. A calendar date is also accepted.",
"label_zh": "日历字段或 MJD,附尺度",
"summary_zh": "调用方说明该数值所在尺度。也接受日历日期。"
},
{
"id": "valid",
"label": "Fields a valid date?",
"kind": "decision",
"group": "validate",
"summary": "The month and day must exist in that year, including the leap year rule.",
"label_zh": "字段是有效日期?",
"summary_zh": "月与日必须在该年中存在,包括闰年规则。"
},
{
"id": "invalid",
"label": "Rejected",
"kind": "terminal",
"group": "error",
"summary": "The fields do not form a valid calendar date, or the request is outside the leap second table.",
"label_zh": "已拒绝",
"summary_zh": "字段不构成有效日历日期,或请求超出闰秒表范围。"
},
{
"id": "to_mjd",
"label": "Convert to a day number",
"kind": "step",
"group": "convert",
"summary": "A calendar date becomes a Modified Julian Date on the stated scale.",
"api": "mjd_from_ymd",
"label_zh": "转换为日编号",
"summary_zh": "日历日期变为指定尺度上的约化儒略日。"
},
{
"id": "scale",
"label": "Which scale?",
"kind": "decision",
"group": "convert",
"summary": "TAI, TT, and GPS convert by a constant offset; UTC converts through the leap second table.",
"label_zh": "哪个尺度?",
"summary_zh": "TAI、TT 与 GPS 按常数偏移转换;UTC 通过闰秒表转换。"
},
{
"id": "constant",
"label": "Apply the constant offset",
"kind": "step",
"group": "convert",
"summary": "TT minus TAI is 32.184 seconds and TAI minus GPS is 19 seconds.",
"api": "Epoch",
"label_zh": "施加常数偏移",
"summary_zh": "TT 减 TAI 为 32.184 秒,TAI 减 GPS 为 19 秒。"
},
{
"id": "leap",
"label": "Look up the leap second offset",
"kind": "step",
"group": "convert",
"summary": "Search the embedded table for the interval that contains the instant.",
"api": "Epoch",
"label_zh": "查找闰秒偏移",
"summary_zh": "在内嵌表中查找包含该时刻的区间。"
},
{
"id": "covered",
"label": "Covered by the table?",
"kind": "decision",
"group": "convert",
"summary": "The table starts at the beginning of 1972.",
"label_zh": "表覆盖该时刻?",
"summary_zh": "表起始于 1972 年初。"
},
{
"id": "tai",
"label": "Epoch on the TAI scale",
"kind": "data",
"group": "store",
"summary": "The instant is stored as a Modified Julian Date on TAI, so the difference between two instants is exact elapsed time.",
"label_zh": "TAI 尺度上的 Epoch",
"summary_zh": "时刻以 TAI 上的约化儒略日存储,因此两个时刻之差恰为经过时间。"
},
{
"id": "read",
"label": "Read back on the requested scale",
"kind": "step",
"group": "convert",
"summary": "The inverse of the entry conversion, producing an MJD and a calendar value.",
"api": "Epoch",
"label_zh": "按要求尺度读回",
"summary_zh": "入口转换的逆变换,产生 MJD 与日历值。"
},
{
"id": "output",
"label": "MJD and calendar on every scale",
"kind": "terminal",
"group": "output",
"summary": "The result reports UTC, TAI, TT, and GPS together with the offset at that instant.",
"label_zh": "各尺度上的 MJD 与日历",
"summary_zh": "结果同时报告 UTC、TAI、TT 与 GPS,以及该时刻的偏移。"
}
],
"edges": [
{
"source": "input",
"target": "valid",
"kind": "flow",
"label": null
},
{
"source": "valid",
"target": "invalid",
"kind": "branch",
"label": "no"
},
{
"source": "valid",
"target": "to_mjd",
"kind": "branch",
"label": "yes"
},
{
"source": "to_mjd",
"target": "scale",
"kind": "flow",
"label": null
},
{
"source": "scale",
"target": "constant",
"kind": "branch",
"label": "TAI, TT, or GPS"
},
{
"source": "scale",
"target": "leap",
"kind": "branch",
"label": "UTC"
},
{
"source": "leap",
"target": "covered",
"kind": "flow",
"label": null
},
{
"source": "covered",
"target": "invalid",
"kind": "branch",
"label": "no"
},
{
"source": "covered",
"target": "tai",
"kind": "branch",
"label": "yes"
},
{
"source": "constant",
"target": "tai",
"kind": "flow",
"label": null
},
{
"source": "tai",
"target": "read",
"kind": "flow",
"label": null
},
{
"source": "read",
"target": "output",
"kind": "flow",
"label": null
}
],
"title_zh": "时间尺度转换",
"summary_zh": "时刻如何进入模型、以单一均匀尺度存储,并以任意支持的尺度读回。"
}