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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

The Space Station integrated refuse management system

The University of Central Florida's design of an Integrated Refuse Management System for the proposed International Space Station is addressed. Four integratable subsystems capable of handling an estimated Orbiter shortfall of nearly 40,000 lbs of refuse produced annually are discussed. The subsystems investigated were: (1) collection and transfer; (2) recycle and reuse; (3) advanced disposal; and (4) propulsion assist in disposal. Emphasis is placed on the recycling or reuse of those materials ultimately providing a source of Space Station refuse. Special consideration is given to various disposal methods capable of completely removing refuse from close proximity of the Space Station. There is evidence that pyrolysis is the optimal solution for disposal of refuse through employment of a Rocket Jettison Vehicle. Additionally, design considerations and specifications of the Refuse Management System are discussed. Optimal and alternate design solutions for each of the four subsystems are summarized. Finally, the system configuration is described and reviewed.

Source record↗
NASA NTRS1988

Semi-automatic development of Payload Operations Control Center software

This report summarizes the current status of CTA's investigation of methods and tools for automating the software development process in NASA Goddard Space Flight Center, Code 500. The emphasis in this effort has been on methods and tools in support of software reuse. The most recent phase of the effort has been a domain analysis of Payload Operations Control Center (POCC) software. This report summarizes the results of the domain analysis, and proposes an approach to semi-automatic development of POCC Application Processor (AP) software based on these results. The domain analysis enabled us to abstract, from specific systems, the typical components of a POCC AP. We were also able to identify patterns in the way one AP might be different from another. These two perspectives--aspects that tend to change from AP to AP, and aspects that tend to remain the same--suggest an overall approach to the reuse of POCC AP software. We found that different parts of an AP require different development technologies. We propose a hybrid approach that combines constructive and generative technologies. Constructive methods emphasize the assembly of pre-defined reusable components. Generative methods provide for automated generation of software from specifications in a very-high-level language (VHLL).

Ballin, Sidney↗
NASA NTRS1994

Taking advantage of ground data systems attributes to achieve quality results in testing software

During the software development life cycle process, basic testing starts with the development team. At the end of the development process, an acceptance test is performed for the user to ensure that the deliverable is acceptable. Ideally, the delivery is an operational product with zero defects. However, the goal of zero defects is normally not achieved but is successful to various degrees. With the emphasis on building low cost ground support systems while maintaining a quality product, a key element in the test process is simulator capability. This paper reviews the Transportable Payload Operations Control Center (TPOCC) Advanced Spacecraft Simulator (TASS) test tool that is used in the acceptance test process for unmanned satellite operations control centers. The TASS is designed to support the development, test and operational environments of the Goddard Space Flight Center (GSFC) operations control centers. The TASS uses the same basic architecture as the operations control center. This architecture is characterized by its use of distributed processing, industry standards, commercial off-the-shelf (COTS) hardware and software components, and reusable software. The TASS uses much of the same TPOCC architecture and reusable software that the operations control center developer uses. The TASS also makes use of reusable simulator software in the mission specific versions of the TASS. Very little new software needs to be developed, mainly mission specific telemetry communication and command processing software. By taking advantage of the ground data system attributes, successful software reuse for operational systems provides the opportunity to extend the reuse concept into the test area. Consistency in test approach is a major step in achieving quality results.

Sigman, Clayton B.↗
NASA NTRS1994

Transportable Payload Operations Control Center reusable software: Building blocks for quality ground data systems

The Mission Operations Division (MOD) at Goddard Space Flight Center builds Mission Operations Centers which are used by Flight Operations Teams to monitor and control satellites. Reducing system life cycle costs through software reuse has always been a priority of the MOD. The MOD's Transportable Payload Operations Control Center development team established an extensive library of 14 subsystems with over 100,000 delivered source instructions of reusable, generic software components. Nine TPOCC-based control centers to date support 11 satellites and achieved an average software reuse level of more than 75 percent. This paper shares experiences of how the TPOCC building blocks were developed and how building block developer's, mission development teams, and users are all part of the process.

Mahmot, Ron↗
NASA NTRS1994

Chemical recycling of scrap composites

There are no well-developed technologies for recycling composite materials other than grinding to produce fillers. New approaches are needed to reclaim these valuable resources. Chemical or tertiary recycling, conversion of polymers into low molecular weight hydrocarbons for reuse as chemicals or fuels, is emerging as the most practical means for obtaining value from waste plastics and composites. Adherent Technologies is exploring a low-temperature catalytic process for recycling plastics and composites. Laboratory results show that all types of plastics, thermosets as well as thermoplastics, can be converted in high yields to valuable hydrocarbon products. This novel catalytic process runs at 200 C, conversion times are rapid, the process is closed and, thus, nonpolluting, and no highly toxic gas or liquid products have been observed so no negative environmental impact will result from its implementation. Tests on reclamation of composite materials show that epoxy, imide, and engineering thermoplastic matrices can be converted to low molecular weight hydrocarbons leaving behind the reinforcing fibers for reuse as composite reinforcements in secondary, lower-performance applications. Chemical recycling is also a means to dispose of sensitive or classified organic materials without incineration and provides a means to eliminate or reduce mixed hazardous wastes containing organic materials.

Allred, Ronald E.↗
NASA NTRS1995

A software bus for thread objects

The authors have implemented a software bus for lightweight threads in an object-oriented programming environment that allows for rapid reconfiguration and reuse of thread objects in discrete-event simulation experiments. While previous research in object-oriented, parallel programming environments has focused on direct communication between threads, our lightweight software bus, called the MiniBus, provides a means to isolate threads from their contexts of execution by restricting communications between threads to message-passing via their local ports only. The software bus maintains a topology of connections between these ports. It routes, queues, and delivers messages according to this topology. This approach allows for rapid reconfiguration and reuse of thread objects in other systems without making changes to the specifications or source code. A layered approach that provides the needed transparency to developers is presented. Examples of using the MiniBus are given, and the value of bus architectures in building and conducting simulations of discrete-event systems is discussed.

Callahan, John R.↗
NASA NTRS1995

The foundations of reusability: Successful experience and important conclusions from planning and scheduling of space operations

NASA's Office of Space Communications is sponsoring a combined technical and management initiative to dramatically decrease the cost of preparing for and conducting space operations. The authors present their successful experience and important conclusions from producing generalized and readily reusable solutions and systems for planning and scheduling applications. While generality by itself should enable reuse, generality alone may not produce the desired cost savings. Generality achieved by accumulating numerous special cases within a software system often increases the complexity of the software to the extent that maintenance costs overtake development savings. Because of this phenomenon, the authors have insisted on simplicity, as well as generality, to achieve cost-effective operation reusability. Simplicity and generality can be accomplished simultaneously when the basic 'Building Blocks' for a problem domain, in this paper, planning and scheduling, are discovered and implemented with reuse in mind. The Building Blocks for planning and scheduling are described. The authors also present examples of how these Building Blocks have accommodated various scenarios that were previously treated as mission-peculiar. Two case histories are presented to demonstrate operational reusability and cost effectiveness.

Hornstein, Rhoda Shaller↗
NASA NTRS1993

Management of Knowledge Representation Standards Activities

Ever since the mid-seventies, researchers have recognized that capturing knowledge is the key to building large and powerful AI systems. In the years since, we have also found that representing knowledge is difficult and time consuming. In spite of the tools developed to help with knowledge acquisition, knowledge base construction remains one of the major costs in building an Al system: For almost every system we build, a new knowledge base must be constructed from scratch. As a result, most systems remain small to medium in size. Even if we build several systems within a general area, such as medicine or electronics diagnosis, significant portions of the domain must be represented for every system we create. The cost of this duplication of effort has been high and will become prohibitive as we attempt to build larger and larger systems. To overcome this barrier we must find ways of preserving existing knowledge bases and of sharing, re-using, and building on them. This report describes the efforts undertaken over the last two years to identify the issues underlying the current difficulties in sharing and reuse, and a community wide initiative to overcome them. First, we discuss four bottlenecks to sharing and reuse, present a vision of a future in which these bottlenecks have been ameliorated, and describe the efforts of the initiative's four working groups to address these bottlenecks. We then address the supporting technology and infrastructure that is critical to enabling the vision of the future. Finally, we consider topics of longer-range interest by reviewing some of the research issues raised by our vision.

Patil, Ramesh S.↗
NASA NTRS1991

Some Interactive Aspects of a Software Design Schema Acquisition Tool

This paper describes a design schema acquisition tool which forms an important component of a hybrid software design system for reuse. The hybrid system incorporates both schema-based approaches in supporting software design reuse activities and is realized by extensions to the IDeA system. The paper also examines some of the interactive aspects that the tool requires with the domain analyst to accomplish its acquisition task.

Lee, Hing-Yan↗
NASA NTRS1993

Management of Knowledge Representation Standards Activities

This report describes the efforts undertaken over the last two years to identify the issues underlying the current difficulties in sharing and reuse, and a community wide initiative to overcome them. First, we discuss four bottlenecks to sharing and reuse, present a vision of a future in which these bottlenecks have been ameliorated, and describe the efforts of the initiative's four working groups to address these bottlenecks. We then address the supporting technology and infrastructure that is critical to enabling the vision of the future. Finally, we consider topics of longer-range interest by reviewing some of the research issues raised by our vision.

Patil, Ramesh S.↗
NASA NTRS1996

Distribution of a Generic Mission Planning and Scheduling Toolkit for Astronomical Spacecraft

Work is progressing as outlined in the proposal for this contract. A working planning and scheduling system has been documented and packaged and made available to the WIRE Small Explorer group at JPL, the FUSE group at JHU, the NASA/GSFC Laboratory for Astronomy and Solar Physics and the Advanced Planning and Scheduling Branch at STScI. The package is running successfully on the WIRE computer system. It is expected that the WIRE will reuse significant portions of the SWAS code in its system. This scheduling system itself was tested successfully against the spacecraft hardware in December 1995. A fully automatic scheduling module has been developed and is being added to the toolkit. In order to maximize reuse, the code is being reorganized during the current build into object-oriented class libraries. A paper describing the toolkit has been written and is included in the software distribution. We have experienced interference between the export and production versions of the toolkit. We will be requesting permission to reprogram funds in order to purchase a standalone PC onto which to offload the export version.

Kleiner, Steven C.↗
NASA NTRS1998

Vehicle and Mission Design Options for the Human Exploration of Mars/Phobos Using "Bimodal" NTR and LANTR Propulsion

The nuclear thermal rocket (NTR) is one of the leading propulsion options for future human missions to Mars because of its high specific impulse (Isp-850-1000 s) capability and its attractive engine thrust-to-weight ratio (approximately equal 3-10). To stay within the available mass and payload volume limits of a "Magnum" heavy lift vehicle, a high performance propulsion system is required for trans-Mars injection (TMI). An expendable TMI stage, powered by three 15 thousand pounds force (klbf) NTR engines is currently under consideration by NASA for its Design Reference Mission (DRM). However, because of the miniscule burnup of enriched uranium-235 during the Earth departure phase (approximately 10 grams out of 33 kilograms in each NTR core), disposal of the TMI stage and its engines after a single use is a costly and inefficient use of this high performance stage. By reconfiguring the engines for both propulsive thrust and modest power generation (referred to as "bimodal" operation), a robust, multiple burn, "power-rich" stage with propulsive Mars capture and reuse capability is possible, A family of modular "bimodal" NTR (BNTR) vehicles are described which utilize a common "core" stage powered by three 15 klbf BNTRs that produce 50 kWe of total electrical power for crew life support, an active refrigeration / reliquification system for long term, "zero-boiloff" liquid hydrogen (LH 2 ) storage, and high data rate communications. An innovative, spine-like "saddle truss" design connects the core stage and payload element and is open underneath to allow supplemental "in-line" propellant tanks and contingency crew consumables to be easily jettisoned to improve vehicle performance. A "modified" DRM using BNTR transfer vehicles requires fewer transportation system elements, reduces IMLEO and mission risk, and simplifies space operations. By taking the next logical step--use of the BNTR for propulsive capture of all payload elements into Mars orbit--the power available in Mars orbit grows to 150 kWe compared to 30 kWe for the DRM. Propulsive capture also eliminates the complex, higher risk aerobraking and capture maneuver which is replaced by a simpler reentry using a standardized, lower mass "aerodescent" shell. The attractiveness of the "all BNTR" option is further increased by the substitution of the lightweight, inflatable "TransHab" module in place of the heavier, hard-shell hab module. Use of TransHab introduces the potential for propulsive recovery and reuse of the BNTR/ERV. It also allows the crew to travel to and from Mar on the same BNTR transfer vehicle thereby cutting the duration of the ERV mission in half--from approximately 4.7 to 2.5 years. Finally, for difficult Mars options, such as Phobos rendezvous and sample return missions, volume (not mass) constraints limit the performance of the "all LH 2 " BNTR stage. The use of "LOX-augmented" NTR (LANTR) engines, operating at a modest oxygen-to-hydrogen mixutre ratio (MR) of 0.5, helps to increase "bulk" propellant density and total thrust during the TMI burn. On all subsequent burns, the bimodal LANTR engines operate on LH 2 only (MR=0) to maximize vehicle performance while staying within the lift capability of two Magnum launches.

Nuclear thermal rocket↗
NASA NTRS1995

The Experience Factory: Strategy and Practice

The quality movement, that has had in recent years a dramatic impact on all industrial sectors, has recently reached the system and software industry. Although some concepts of quality management, originally developed for other product types, can be applied to software, its specificity as a product which is developed and not produced requires a special approach. This paper introduces a quality paradigm specifically tailored on the problem of the systems and software industry. Reuse of products, processes and experiences originating from the system life cycle is seen today as a feasible solution to the problem of developing higher quality systems at a lower cost. In fact, quality improvement is very often achieved by defining and developing an appropriate set of strategic capabilities and core competencies to support them. A strategic capability is, in this context, a corporate goal defined by the business position of the organization and implemented by key business processes. Strategic capabilities are supported by core competencies, which are aggregate technologies tailored to the specific needs of the organization in performing the needed business processes. Core competencies are non-transitional, have a consistent evolution, and are typically fueled by multiple technologies. Their selection and development requires commitment, investment and leadership. The paradigm introduced in this paper for developing core competencies is the Quality Improvement Paradigm which consists of six steps: (1) Characterize the environment, (2) Set the goals, (3) Choose the process, (4) Execute the process, (5) Analyze the process data, and (6) Package experience. The process must be supported by a goal oriented approach to measurement and control, and an organizational infrastructure, called Experience Factory. The Experience Factory is a logical and physical organization distinct from the project organizations it supports. Its goal is development and support of core competencies through capitalization and reuse of its cycle experience and products. The paper introduces the major concepts of the proposed approach, discusses their relationship with other approaches used in the industry, and presents a case in which those concepts have been successfully applied.

Basili, Victor R.↗
NASA NTRS2000

System Design Techniques for Reducing the Power Requirements of Advanced life Support Systems

The high power requirement associated with overall operation of regenerative life support systems is a critical Z:p technological challenge. Optimization of individual processors alone will not be sufficient to produce an optimized system. System studies must be used in order to improve the overall efficiency of life support systems. Current research efforts at NASA Ames Research Center are aimed at developing approaches for reducing system power and energy usage in advanced life support systems. System energy integration and energy reuse techniques are being applied to advanced life support, in addition to advanced control methods for efficient distribution of power and thermal resources. An overview of current results of this work will be presented. The development of integrated system designs that reuse waste heat from sources such as crop lighting and solid waste processing systems will reduce overall power and cooling requirements. Using an energy integration technique known as Pinch analysis, system heat exchange designs are being developed that match hot and cold streams according to specific design principles. For various designs, the potential savings for power, heating and cooling are being identified and quantified. The use of state-of-the-art control methods for distribution of resources, such as system cooling water or electrical power, will also reduce overall power and cooling requirements. Control algorithms are being developed which dynamically adjust the use of system resources by the various subsystems and components in order to achieve an overall goal, such as smoothing of power usage and/or heat rejection profiles, while maintaining adequate reserves of food, water, oxygen, and other consumables, and preventing excessive build-up of waste materials. Reductions in the peak loading of the power and thermal systems will lead to lower overall requirements. Computer simulation models are being used to test various control system designs.

Finn, Cory↗
NASA NTRS2000

Ground Data System Risk Mitigation Techniques for Faster, Better, Cheaper Missions

With the advent of faster, cheaper, and better missions, NASA Projects acknowledged that a higher level of risk was inherent and accepted with this approach. It was incumbent however upon each component of the Project whether spacecraft, payload, launch vehicle, or ground data system to ensure that the mission would nevertheless be an unqualified success. The Small Explorer (SMEX) program's ground data system (GDS) team developed risk mitigation techniques to achieve these goals starting in 1989. These techniques have evolved through the SMEX series of missions and are practiced today under the Triana program. These techniques are: (1) Mission Team Organization--empowerment of a closeknit ground data system team comprising system engineering, software engineering, testing, and flight operations personnel; (2) Common Spacecraft Test and Operational Control System--utilization of the pre-launch spacecraft integration system as the post-launch ground data system on-orbit command and control system; (3) Utilization of operations personnel in pre-launch testing--making the flight operations team an integrated member of the spacecraft testing activities at the beginning of the spacecraft fabrication phase; (4) Consolidated Test Team--combined system, mission readiness and operations testing to optimize test opportunities with the ground system and spacecraft; and (5). Reuse of Spacecraft, Systems and People--reuse of people, software and on-orbit spacecraft throughout the SMEX mission series. The SMEX ground system development approach for faster, cheaper, better missions has been very successful. This paper will discuss these risk management techniques in the areas of ground data system design, implementation, test, and operational readiness.

Catena, John J.↗
NASA NTRS1994

SIGMA: A Knowledge-Based Simulation Tool Applied to Ecosystem Modeling

The need for better technology to facilitate building, sharing and reusing models is generally recognized within the ecosystem modeling community. The Scientists' Intelligent Graphical Modelling Assistant (SIGMA) creates an environment for model building, sharing and reuse which provides an alternative to more conventional approaches which too often yield poorly documented, awkwardly structured model code. The SIGMA interface presents the user a list of model quantities which can be selected for computation. Equations to calculate the model quantities may be chosen from an existing library of ecosystem modeling equations, or built using a specialized equation editor. Inputs for dim equations may be supplied by data or by calculation from other equations. Each variable and equation is expressed using ecological terminology and scientific units, and is documented with explanatory descriptions and optional literature citations. Automatic scientific unit conversion is supported and only physically-consistent equations are accepted by the system. The system uses knowledge-based semantic conditions to decide which equations in its library make sense to apply in a given situation, and supplies these to the user for selection. "Me equations and variables are graphically represented as a flow diagram which provides a complete summary of the model. Forest-BGC, a stand-level model that simulates photosynthesis and evapo-transpiration for conifer canopies, was originally implemented in Fortran and subsequenty re-implemented using SIGMA. The SIGMA version reproduces daily results and also provides a knowledge base which greatly facilitates inspection, modification and extension of Forest-BGC.

Dungan, Jennifer L.↗
NASA NTRS1994

A Formal Approach to Domain-Oriented Software Design Environments

This paper describes a formal approach to domain-oriented software design environments, based on declarative domain theories, formal specifications, and deductive program synthesis. A declarative domain theory defines the semantics of a domain-oriented specification language and its relationship to implementation-level subroutines. Formal specification development and reuse is made accessible to end-users through an intuitive graphical interface that guides them in creating diagrams denoting formal specifications. The diagrams also serve to document the specifications. Deductive program synthesis ensures that end-user specifications are correctly implemented. AMPHION has been applied to the domain of solar system kinematics through the development of a declarative domain theory, which includes an axiomatization of JPL's SPICELIB subroutine library. Testing over six months with planetary scientists indicates that AMPHION's interactive specification acquisition paradigm enables users to develop, modify, and reuse specifications at least an order of magnitude more rapidly than manual program development. Furthermore, AMPHION synthesizes one to two page programs consisting of calls to SPICELIB subroutines from these specifications in just a few minutes. Test results obtained by metering AMPHION's deductive program synthesis component are examined. AMPHION has been installed at JPL and is currently undergoing further refinement in preparation for distribution to hundreds of SPICELIB users worldwide. Current work to support end-user customization of AMPHION's specification acquisition subsystem is briefly discussed, as well as future work to enable domain-expert creation of new AMPHION applications through development of suitable domain theories.

Lowry, Michael↗
NASA NTRS1994

User Interface Technology for Formal Specification Development

Formal specification development and modification are an essential component of the knowledge-based software life cycle. User interface technology is needed to empower end-users to create their own formal specifications. This paper describes the advanced user interface for AMPHION1 a knowledge-based software engineering system that targets scientific subroutine libraries. AMPHION is a generic, domain-independent architecture that is specialized to an application domain through a declarative domain theory. Formal specification development and reuse is made accessible to end-users through an intuitive graphical interface that provides semantic guidance in creating diagrams denoting formal specifications in an application domain. The diagrams also serve to document the specifications. Automatic deductive program synthesis ensures that end-user specifications are correctly implemented. The tables that drive AMPHION's user interface are automatically compiled from a domain theory; portions of the interface can be customized by the end-user. The user interface facilitates formal specification development by hiding syntactic details, such as logical notation. It also turns some of the barriers for end-user specification development associated with strongly typed formal languages into active sources of guidance, without restricting advanced users. The interface is especially suited for specification modification. AMPHION has been applied to the domain of solar system kinematics through the development of a declarative domain theory. Testing over six months with planetary scientists indicates that AMPHION's interactive specification acquisition paradigm enables users to develop, modify, and reuse specifications at least an order of magnitude more rapidly than manual program development.

Lowry, Michael↗