Engineering topics

Sherif, Josef S.

Publications and source records attributed to Sherif, Josef S..

4 records

NASA NTRS1995

Object-Oriented Software Metrics for Predicting Reusability and Estimating Size

As object-oriented software development methods come into more widespread use, basic questions of software quality assurance must be reconsidered. We will highlight efforts now underway at NASA's Jet Propulsion Laboratory to both assess the quality of software systems developed using object oriented technology and develop guidelines for future development of such systems. The current focus is on design and code reusability., and system size estimation. A number of metrics are proposed and two software systems measured and analyzed. The preliminary results reported here should be useful to software development and quality assurance personnel working in C++ implementation environment.

Sanderson, D. Peter↗

NASA NTRS1995

An Overview of the Quality Function Deployment (QFD) Technique

QFD is a product planning tool and a process methodology that enables all organizations, departments, and individuals in a business or a project to systematically focus on the critical performance, functions, and/or characteristics of a product that are the most important to the customer. It is part of the Total Quality Management (TQM) concept.. This presentation describes the objectives of QFD, the process for implementing the technique, the benefits derived from proper implementation, the kinds of systems where QFD is best utilized, what the success factors are, how QFD works, some guidelines for selection of a QFD team, and the functional roles of key team members.

Quality Function Deployment QFD customer focus cus↗

NASA NTRS1992

Determining maintenance cost ratios

This paper reports on the wide range of costs involved in maintaining equipment and discusses methods that different industries use to measure and report their maintenance cost. Results are presented of the study of maintenance costs in the NASA Deep Space Network (DSN) and of a comparison of DSN maintenance cost with the maintenance costs of a number of other reports. A comparison of the maintenance costs in terms of the maintenance cost ratio (annual maintenance cost/capital replacement cost) shows that DSN has the lowest maintenance cost ratio of the industries and organizations surveyed.

Remer, Donald S.↗

NASA NTRS1992

Modeling the Deep Space Network costs for future space missions by using major cost drivers

This paper develops a cost model to do long range planning cost estimates for Deep Space Network (DSN) support of future space missions. The model is a function of eight major mission cost drivers such as uplink frequency upgrade, telemetry upgrade, and antenna gain/noise temperature upgrade. This paper focuses on the costs required to modify and/or enhance the DSN to prepare for supporting future space missions. Two models are derived from actual cost data from three space missions: Voyager (Uranus), Voyager (Neptune), and Magellan. Model A makes it possible to estimate the total cost, and Model B makes it possible to estimate the time profile cost and total cost for DSN support of a similar future space mission. The models were back tested against the total cost and the time profile cost for DSN support of the three projects, and gave cost estimates which range from 17 percent below to 19 percent above actual costs for Model A, and 22.5 percent below to 17.5 percent above for Model B. The total cost Model A was also applied to estimate the total costs for DSN support of two other independent projects: Mariner Jupiter/Saturn (MJS later became Voyager), and Viking. This model gave total cost estimates for DSN support which range from 15 percent to 4 percent above actual total costs for MJS and Viking, respectively.

Remer, Donald S.↗