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Chafin, R. L.

Publications and source records attributed to Chafin, R. L..

7 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

The measurement of operator workload in the Mark IVA DSCC monitor and control subsystem

An operator workload measurement methodology is presented which will be used in support of the Mark IVA operational test and evaluation plan. Three operator workload measures are suggested: operator ratings, primary task work measures, and information processing time measures. A method of validating the workload measures using secondary task work measures is presented. It is expected that operations testing using these measures will assist in establishing the time required to perform essential operational activities and will indicate high risk operations areas due to potential operator overload.

Lemay, M.↗
NASA NTRS1982

Human factors in operations design

The manner in which organizations develop their organizational structure is considered, taking into account an example in which the environment changes for an older organization. In such cases, it would be preferable to have some theoretical foundation on which to base the restructuring of the organization to meet new environmental needs. A description is given of a theoretic foundation based on the principles of Differentiation/Integration and Procedural/Knowledge based operations. The organizational design principle of Differentiation and Integration has been presented by Lawrence and Lorsch (1969). The differentiation/integration processes are related to the organizational structures presented in studies concerning NASA Deep Space Network (DSN) operations. The principles presented provide valuable tools for analyzing operations organization.

Chafin, R. L.↗
NASA NTRS1982

NASA Deep Space Network operations organization

The organization of the NASA Deep Space Network (DSN), a network of tracking station control and data handling facilities, is briefly reviewed. It has been designed, constructed, maintained, and operated by the Jet Propulsion Laboratory at California Institute of Technology in support of NASA lunar and interplanetary flight programs. Some important technological and organizational advances made by DSN since the early development of spacecraft tracking in the 1950s are considered.

Chafin, R. L.↗
NASA NTRS1981

A model for the control mode man-computer interface dialogue

A four stage model is presented for the control mode man-computer interface dialogue. It consists of context development, semantic development syntactic development, and command execution. Each stage is discussed in terms of the operator skill levels (naive, novice, competent, and expert) and pertinent human factors issues. These issues are human problem solving, human memory, and schemata. The execution stage is discussed in terms of the operators typing skills. This model provides an understanding of the human process in command mode activity for computer systems and a foundation for relating system characteristics to operator characteristics.

Chafin, R. L.↗
NASA NTRS1980

DSN human factors project

The project plan was to hold focus groups to identify the factors influencing the ease of use characteristics of software and to bond the problem. A questionnaire survey was conducted to evaluate those factors which were more appropriately measured with that method. The performance oriented factors were analyzed and relationships hypothesized. The hypotheses were put to test in the experimental phase of the project. In summary, the initial analysis indicates that there is an initial performance effect favoring computer controlled dialogue but the advantage fades fast as operators become experienced. The user documentation style is seen to have a significant effect on performance. The menu and prompt command formats are preferred by inexperienced operators. The short form mnemonic is least favored. There is no clear best command format but the short form mnemonic is clearly the worst.

Chafin, R. L.↗
NASA NTRS1980

Simplicity in command and control systems - A human factors consideration

The importance of simplicity in the man computer interface (MCI) is stressed because of the effect it has on the system containing the MCI. Results are used from an MCI study at the Jet Propulsion Laboratory to find an area where the system MCIs can be simplified. The circumstances under which these simplifications are appropriate are listed. The concepts of cognitive simplicity and process simplicity are presented as design alternatives for the MCI. In addition, the concepts of understandability, operation, learnability, level of learning, and usability are presented as tools for the system designer. The use of these concepts in developing a systematic MCI design is discussed.

Chafin, R. L.↗