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R. T. Cheng

Publications and source records attributed to R. T. Cheng.

61 records · Page 4Linked to original sources
USGS1979

A microcomputer based system for current-meter data acquisition

The U.S. Geological Survey is conducting current measurements as part of an interdisciplinary study of the San Francisco Bay estuarine system. The current meters used in the study record current speed, direction, temperature, and conductivity in digital codes on magnetic tape cartridges. Upon recovery of the current meters, the data tapes are translated by a tape reader into computer codes for further analyses. Quite often the importance of the data processing phase of a current-measurement program is underestimated and downplayed. In this paper a data-processing system which performs the complete data processing and analyses is described. The system, which is configured around an LSI-11 microcomputer, has been assembled to provide the capabilities of data translation, reduction, and tabulation and graphical display immediately following recovery of current meters. The flexibility inherent in a microcomputer has made it available to perform many other research functions which would normally be done on an institutional computer.

Conference Paper↗
USGS1978

Comparison of a few recording current meters in San Francisco Bay, CA

A team of research scientists in the U.S. Geological Survey uses San Francisco Bay, California, as an outdoor laboratory to study complicated interactions of physical, chemical, and biological processes which take place in an estuarine environment. A current meter comparison study was conceived because of the need to select a suitable current meter to meet field requirements for current measurements in the Bay. The study took place in south San Francisco Bay, California, in the spring of 1977. An instrument tower which was designed to support instruments free from the conventional mooring line motions was constructed and emplaced in south San Francisco Bay. During a period of two months, four types of recording current meters have been used in the tests. The four types were: (1) Aanderaa, (2) tethered shroud-impeller, (3) drag-inclinometer, and (4) electromagnetic current meters. With the exception of the electromagnetic current meter, one of each type was mounted on the instrument tower, and one of each type was deployed on moorings near the instrument tower. In addition, a wind anemometer and a recording tide gauge were also installed on the tower. This paper discusses the characteristics of each instrument and the accuracy that each instrument can provide when used in an estuarine environment. We pay special attention to our experiences in the field operation with respect to handling of the instruments and to our experiences working up the raw data in the post-deployment data analysis.

California↗