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  • 1
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    Publication Date: 2011-08-24
    Description: GMAS was designed as a general control framework to satisfy multiple applications in a core-limited and optionally interactive environment. During execution, the system uses and releases memory as needed to provide the user with a system that is only as large or small as the problem demands. Although GMAS was designed for trajectory-related spacecraft mission analysis specifications, the organization of the system software makes GMAS applicable to many computational functions. Any large computer program that can be separated into independent functional areas (load modules) can probably be implemented under GMAS. Because of the program's modular nature, the GMAS system offers software development time savings, core savings and efficiency, stability, and flexibility. The major components of GMAS are the executive module, the dynamic load modules, the dynamic arrays, and the automatic sequence. The GMAS executive module is primarily responsible for interpretation of user control directives and data management. The executive passes control to user-designated dynamic load modules after having prepared user-specified and default data for the utilities. The executive also controls the dynamic assignment and release of core-space for user-specified modules and data areas. The dynamic load modules contain the applications software to be used in specific problem solutions. These load modules may consist of the GMAS library of standard routines along with user developed libraries of routines. Each dynamic load module is a separate group of subroutines which, when loading during GMAS execution, can be executed to solve part of the user problem then deleted from core. Dynamic load module input and output can be transferred through out-of-core files or through user-specified dynamic arrays located in a core area separate from the executive and any dynamic load modules. The dynamic arrays are the primary communications link between load modules. The GMAS automatic sequence allows the user to control the other 3 components. The user creates the automatic sequence, or application program, by using a simple control language which has been created especially for GMAS. The automatic sequence contains the names of executive modules and utility load modules; data for these modules; and logical operation directives. GMAS capabilities include simulation of satellite orbits, shadow and station coverage studies, targeting and optimization capability, a Monte Carlo error analysis package, and a graphing capability that can be used to generate comparison graphs of selected orbital parameters of two satellites. Interactive graphics are provided for in the form of tabular, plot, and message display capabilities for the IBM 3250 and 2250 display devices. GMAS includes a very comprehensive set of over 600 orbital calculation routines which handle a variety of functions, including: performing impulsive maneuvers while controlling the altitude of the spacecraft; providing acquisition tables for ground station and tracking and data relay satellite coverage; estimating the effects of spacecraft thrust on the orbit; developing maneuver commands by modeling the hydrazine propulsion system of the spacecraft; sequentially summing the gravitational effects for each perturbing body using an independent two body model; generating plots of combinations of dynamic arrays on a Cartesian grid; and determining visibility status and pointing angles from the view of the spacecraft. GMAS is written in FORTRAN (75%), JCL (17%), and Assembler (8%) for implementation on the IBM 370 series under the IBM 370 MVS Operating System running under VM and under the IBM VM/SP CMS Operating System. The executive component, which is always resident in core, has a central memory requirement of approximately 220K. GMAS was developed in 1977 and last updated in 1988.
    Keywords: ASTRODYNAMICS
    Type: GSC-12392
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  • 2
    Publication Date: 2006-02-14
    Description: It has been estimated that NASA expends anywhere from 6 to 10 percent of its annual budget on the acquisition, implementation and maintenance of computer software. Although researchers have produced numerous software engineering approaches over the past 5-10 years; each claiming to be more effective than the other, there is very limited quantitative information verifying the measurable impact htat any of these technologies may have in a production environment. At NASA/GSFC, an extended research effort aimed at identifying and measuring software techniques that favorably impact productivity of software development, has been active over the past 8 years. Specific, measurable, software development technologies have been applied and measured in a production environment. Resulting software development approaches have been shown to be effective in both improving quality as well as productivity in this one environment.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: NASA. Johnson (Lyndon B.) Space Center R and D Productivity: New Challenges for the US Space Program; p 249-263
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  • 3
    Publication Date: 2016-06-07
    Description: The Software Engineering Laboratory (SEL) is an organization created nearly 10 years ago for the purpose of identifying, measuring and applying quality software engineering techniques in a production environment. The members of the SEL include NASA/Goddard Space Flight Center (GSFC, the sponsor and organizer), University of Maryland, and Computer Sciences Corporation. Since its inception the SEL has conducted numerous experiments, and has evaluated a wide range of software technologies. This paper describes several of the more recent experiments as well as some of the general conclusions to which the SEL has arrived.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: Proceedings of Tenth Annual Software Engineering Workshop; 37 p
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  • 4
    Publication Date: 2013-08-31
    Description: Results are reported from a series of investigations into the effectiveness of various methods and tools used in a software production environment. The basis for the analysis is a project data base, built through extensive data collection and process instrumentation. The project profiles become an organizational memory, serving as a reference point for an active program of measurement and experimentation on software technology.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: Collected Software Engineering Papers, Volume 2; 5 p
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  • 5
    Publication Date: 2019-06-28
    Description: The strategies of code reading, functional testing, and structural testing are compared in three aspects of software testing: fault detection effectiveness, fault detection cost, and classes of faults detected. The major results are the following: (1) Code readers detected more faults than did those using the other techniques, while functional tester detected more faults than did structural testers; (2) Code readers had a higher fault detection rate than did those using the other methods, while there was no difference between functional testers and structural testers; (3) Subjects testing the abstract data type detected the most faults and had the highest fault detection rate, while individuals testing the database maintainer found the fewest faults and spent the most effort testing; (4) Subjects of intermediate and junior expertise were not different in number or percentage of faults found, fault detection rate, or fault detection effort; (5) subjects of advanced expertise found a greater number of faults than did the others, found a greater percentage of faults than did just those of junior expertise, and were not different from the others in either fault detection rate or effort; and (6) Code readers and functional testers both detected more omission faults and more control faults than did structural testers, while code readers detected more interface faults than did those using the other methods.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: Proceedings of the Ninth Annual Software Engineering Workshop; p 42-64
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  • 6
    Publication Date: 2016-06-07
    Description: Software engineering research is reported. Data acquisition is reported.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: Proc. of the 7th Ann. Software Eng. Workshop; 34 p
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  • 7
    Publication Date: 2019-06-28
    Description: Multipurpose programs, routines and operating systems are described. Data conversion and character string comparison subroutine are included. Graphics packages, and file maintenance programs are also included.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: NASA-TM-84799 , STL-81-003 , NAS 1.15:84799
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  • 8
    Publication Date: 2019-06-28
    Description: A guide is presented for National Aeronautics and Space Administration management personnel who stand to benefit from the lessons learned in developing microprocessor-based flight dynamics software systems. The essential functional characteristics of microprocessors are presented. The relevant areas of system support software are examined, as are the distinguishing characteristics of flight dynamics software. Design examples are provided to illustrate the major points presented, and actual development experience obtained in this area is provided as evidence to support the conclusions reached.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: NASA-TM-84794 , STL-80-001 , NAS 1.15:84794
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  • 9
    Publication Date: 2019-06-28
    Description: A system description of, and user's guide for, the Configuration Analysis Tool (CAT) are presented. As a configuration management tool, CAT enhances the control of large software systems by providing a repository for information describing the current status of a project. CAT provides an editing capability to update the information and a reporting capability to present the information. CAT is an interactive program available in versions for the PDP-11/70 and VAX-11/780 computers.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: NASA-TM-85398 , SEL-80-104-REV , NAS 1.15:85398 , CSC/SD-82/6125-REV
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  • 10
    Publication Date: 2019-06-28
    Description: The structure of the Software Engineering Laboratory (SEL) data base is described. It defines each data base file in detail and provides information about how to access and use the data for programmers and other users. Several data base reporting programs are described also.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: NASA-TM-85397 , SEL-81-102-REV , NAS 1.15:85397 , CSC/SD-83/6012-REV
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