How can I get to Nansha Central Hospital from Shiqiao
because power (kw) = torque (nm) × Speed (RPM) / 9549, so the output torque (nm) = 9549 x η X input power (kw) / speed (RPM).
the specific numerical calculation should be supplemented.
friction angle = arctan μ μ It is friction factor)
friction factor is related to contact line, lubricating oil, sliding speed, material matching, processing, installation accuracy, heat treatment, etc., which is difficult to determine, only recommended value
you can refer to the manual, for example, when the sliding speed is 0.1m/s, the friction factor is 0.08, and the friction angle is 4 ° 34'
bus line: Metro Line 7 → Metro Line 4, the whole journey is about 51.9 km
1. Take Metro Line 7 from Guangzhou south station, pass 8 stops, and reach University City South Station
2. Take Metro Line 4, pass 9 stops, and reach Jinzhou station
3. Walk about 1.0 km to Nansha central hospital
ETL is the abbreviation of English extract transform load, which is used to describe the process of extracting, transforming and loading data from the source to the destination. ETL is commonly used in data warehouse, but its object is not limited to data warehouse
Generally, ETL or ELT (extract load transform) are used in the process described by ETL. Generally, the larger the amount of data, the more complex the conversion logic, and the database with strong computing power at the destination, the more apt is used to make use of the parallel processing power of the database at the destination 
extended data
ETL has several characteristics:
one is data synchronization, which is not a one-time data pull, it is a regular activity, according to a fixed cycle, and even now some people put forward the concept of real-time ETL
The second is the amount of data, which is generally huge. It is worth splitting the data flow process into e, t and L<source: Internet ETL
The typical representatives of ETL tools are: Informatica, Datastage, OWB, Microsoft DTS, beeload, kettle, Jiuqi ETL...
the open source tools are eclipse ETL plug-in: cloveretl
Data Integration: fast implementation of ETL
the quality problems of ETL are manifested in correctness, integrity, consistency, completeness, effectiveness, timeliness and accessibility. There are many reasons that affect the quality of the system. The main reasons caused by the system integration and historical data include: the data model of the business system is inconsistent in different periods of time; The business process of business system changes in different periods; The old system mole is inconsistent in operation, personnel, finance, office system and other related information; The inconsistency caused by incomplete data integration of legacy system, new business and management system
to implement ETL, the first step is to implement the ETL conversion process. It can be reflected in the following aspects:
1. Null value processing: it can capture the null value of the field, load or replace it with other meaningful data, and load it to different target databases according to the null value of the field
2. Standardized data format: the definition of field format constraints can be realized, and the loading format can be customized for time, value, character and other data in the data source
3. Split data: fields can be broken down according to business requirements. For example, the calling number is 861082585313-8148, which can be decomposed into area code and telephone number
4. Verify the correctness of the data: you can use the lookup and split functions to verify the data. For example, after the calling number 861082585313-8148 is decomposed into area code and telephone number, lookup can be used to return the calling area recorded by the calling gateway or switch for data verification
5. Data replacement: e to business factors, invalid data and missing data can be replaced
6. Lookup: find the missing data. Lookup implements sub query and returns the missing fields obtained by other means to ensure the integrity of the fields
7. Set up the primary and foreign key constraints of ETL process: for the non dependent illegal data, it can be replaced or exported to the error data file to ensure the loading of the unique record of the primary key
Laptop means:
n; Notebook computer; læ ptɒ p] Beauty [&; læ pt ɑ&# 720; p] The laptop is three times more expensive than that desktop
(3) vocabulary usage / Collocation:laptop computer; Laptop computer...
extended data:
synonym: computer
1. Meaning: n. computer; Computer
2. Pronunciation: English [K & # 601; m' pjuː tə( r)] Beauty [K & # 601; m' pjuː tə r] (3) examples:
I & # 39; M getting a new computer for birthday present
The basic meaning of computer is "computer", which can also be translated as "computer" Computer is a countable noun