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At least 1,027 records · Page 57

A survey of payload integration methods

Several full-scale and short-cut methods for analyzing a booster/payload system are presented. Two full-scale techniques are considered: (1) a technique that uses a restrained payload together with a free-booster model, the latter being augmented with residual mass and stiffness correction and (2) a technique that uses a restrained payload and booster model. Both techniques determine the 'modal modes', which require the solution of a system eigenvalue problem; the loads usually are then determined via an acceleration approach. A brief description is given of a number of short-cut methods which are of special interest to Shuttle payload design: structural modification, base drive, and interface impedance methods. Directions for further research and development are suggested.

Engels, R. C.↗

A study of the very high order natural user language (with AI capabilities) for the NASA space station common module

The requirements are identified for a very high order natural language to be used by crew members on board the Space Station. The hardware facilities, databases, realtime processes, and software support are discussed. The operations and capabilities that will be required in both normal (routine) and abnormal (nonroutine) situations are evaluated. A structure and syntax for an interface (front-end) language to satisfy the above requirements are recommended.

Gill, E. N.↗

Crystalline-silicon photovoltaics summary module design and reliability

The evolution of the design and reliability of solar modules was described. Design requirements involved 14 different considerations, including residential building and material electrical codes, wind-loading, hail impact, operating temperature levels, module flammability, and interfaces for both the array structure and the operation of the system. Reliability research involved in diverse investigations including glass-fracture strength, soiling levels, electrochemical corrosion, and bypass-diode qualification tests. Based on these internationally recognized studies, performance assessments, and failure analyses, the Flat-plate Solar Array Project in its 11-year duration served to nuture the development of 45 different solar module designs from 15 PV manufacturers.

Ross, R. G., Jr.↗

Shuttle orbit flight control design lessons - Direction for Space Station

The Space Shuttle orbit flight control system, which operates during all exo-atmospheric flight phases, has successfully met operational requirements. Many design integration and operational issues that required resolution during development and testing provide an experience base that will benefit the development of future space systems, particularly the Space Station. To this end, the applicable Shuttle and Space Station hardware/software is reviewed with some perspective provided on how current design groundrules were derived and how issues that affected the Shuttle orbit control system design are a pathway for the Space Station. Some of the most significant lessons learned from the Shuttle are summarized, with a discussion of the effect of performance and design of hardware, including the data processing system on software structures and usage procedures. Crew interface issues and important results from man-in-the-loop tests are summarized. Problems resulting from trying to meet difficult orbital operational objectives, including some sophisticated payload operations are characterized. Several proposed Shuttle flight control design improvements, developed in response to some of the lessons learned so far, are identified. Potential application of the Shuttle design lessons and new control technologies to the Space Station are discussed.

Cox, Kenneth J.↗

Toward a mathematical formalism of performance, task difficulty, and activation

The rudiments of a mathematical formalism for handling operational, physiological, and psychological concepts are developed for use by the man-machine system design engineer. The formalism provides a framework for developing a structured, systematic approach to the interface design problem, using existing mathematical tools, and simplifying the problem of telling a machine how to measure and use performance.

Samaras, George M.↗

QUEST/Ada (Query Utility Environment for Software Testing) of Ada: The development of a program analysis environment for Ada

A history of the Query Utility Environment for Software Testing (QUEST)/Ada is presented. A fairly comprehensive literature review which is targeted toward issues of Ada testing is given. The definition of the system structure and the high level interfaces are then presented. The design of the three major components is described. The QUEST/Ada IORL System Specifications to this point in time are included in the Appendix. A paper is also included in the appendix which gives statistical evidence of the validity of the test case generation approach which is being integrated into QUEST/Ada.

Brown, David B.↗

On-orbit operations of the Space Station Freedom attached payloads accommodations equipment

The Space Station Freedom which will serve as a base of operations for instruments performing space science is discussed. The Attached Payload Accommodation Equipment (APAE) will be a set of equipment designed to provide standard structural, power, data and thermal interfaces between payloads and the space station. The APAE is designed to minimize and simplify the on-orbit operations required for payload installation, replacement, and servicing. In addition, the APAE supplies launch support for small payloads and attitude control for payloads that required it.

Lane, Jean Folse↗

Sensor fusion: Spatial reasoning and scene interpretation; Proceedings of the Meeting, Cambridge, MA, Nov. 7-9, 1988

The present conference discusses topics in the fusion of active and passive sensors, object estimation and verification, three-dimensional representation and knowledge integration, three-dimensional perception from multisensor data, the representation of uncertainty in multisensor fusion, and sensor calibration and registration. Also discussed are the areas of multisensor target detection and classification, multisensor processing architectures, knowledge structures and spatial reasoning, sensory interfaces to telerobotic systems, and navigation with spatial data bases.

Schenker, Paul S.↗

A spectral multi-domain technique applied to high-speed chemically reacting flows

The first applications of a spectral multidomain method for viscous compressible flow is presented. The method imposes a global flux balance condition at the interface so that high-order continuity of the solution is preserved. The global flux balance is imposed in terms of a spectral integral of the discrete equations across adjoining domains. Since the discretized equations interior to each domain solved are uncoupled from each other, and since the interface relation has a block structure, the solution scheme can be adapted to the particular requirements of each subdomain. The spectral multidomain technique presented is well-suited for the multiple scales associated with the chemically reacting and transition flows in hypersonic research. A nonstaggered multidomain discretization is used for the chemically reacting flow calculation, and the first implementation of a staggered multidomain mesh is presented for accurately solving the stability equation for a viscous compressible fluid.

Macaraeg, Michele G.↗

Two pass method and radiation interchange processing when applied to thermal-structural analysis of large space truss structures

A method of efficient and automated thermal-structural processing of very large space structures is presented. The method interfaces the finite element and finite difference techniques. It also results in a pronounced reduction of the quantity of computations, computer resources and manpower required for the task, while assuring the desired accuracy of the results.

Warren, Andrew H.↗

Cryogenic propellant thermal control system design considerations, analyses, and concepts applied to a Mars human exploration mission

This paper analyzes, defines, and sizes cryogenic storage thermal control systems that meet the requirements of future NASA Mars human exploration missions. The design issues of this system include the projection of the existing Multilayer Insulation data base for cryogenic storage to much thicker (10 cm or more) insulation systems, the unknown heat leak from mechanical interfaces, and the thermal and structural performance effects of the large tank sizes required for a Mars mission. Acknowledging these unknown effects, heat loss projections are made based on extrapolation of the existing data base. The results indicate that hydrogen, methane, and oxygen are feasible propellants, and that the best suited thermal control sytems are 'thick' MLI, thermodynamic vent sytems, cryocoolers, and vacuum jackets.

Plachta, David W.↗

Hybrid silicon focal plane arrays

Applications were demonstrated for hybrid silicon infrared CCD arrays in both ground and space based astronomical instrumentation. The primary goal was to provide a point of departure for both instrument designs and further development of the device. The test device is an indium doped silicon (Si:In) version of the 32 x 32 Rockwell 30331 surface channel hybrid silicon IRCCD. The device structure and a typical instrument interface are shown. The motivation for further study is presented along with a discussion in detail of some of the issues.

Pommerrenig, D.↗

An analysis of fiber-matrix interface failure stresses for a range of ply stress states

A graphite/bismaleimide laminate was prepared without the usual fiber treatment and was tested over a wide range of stress states to measure its ply cracking strength. These tests were conducted using off-axis flexure specimens and produced fiber-matrix interface failure data over a correspondingly wide range of interface stress states. The absence of fiber treatment, weakened the fiber-matrix interfaces and allowed these tests to be conducted at load levels that did not yield the matrix. An elastic micromechanics computer code was used to calculate the fiber-matrix interface stresses at failure. Two different fiber-array models (square and diamond) were used in these calculations to analyze the effects of fiber arrangement as well as stress state on the critical interface stresses at failure. This study showed that both fiber-array models were needed to analyze interface stresses over the range of stress states. A linear equation provided a close fit to these critical stress combinations and, thereby, provided a fiber-matrix interface failure criterion. These results suggest that prediction procedures for laminate ply cracking can be based on micromechanics stress analyses and appropriate fiber-matrix interface failure criteria. However, typical structural laminates may require elastoplastic stress analysis procedures that account for matrix yielding, especially for shear-dominated ply stress states.

Crews, J. H.↗

Solid Modeling Aerospace Research Tool (SMART) user's guide, version 2.0

The Solid Modeling Aerospace Research Tool (SMART) software package is used in the conceptual design of aerospace vehicles. It provides a highly interactive and dynamic capability for generating geometries with Bezier cubic patches. Features include automatic generation of commonly used aerospace constructs (e.g., wings and multilobed tanks); cross-section skinning; wireframe and shaded presentation; area, volume, inertia, and center-of-gravity calculations; and interfaces to various aerodynamic and structural analysis programs. A comprehensive description of SMART and how to use it is provided.

Mcmillin, Mark L.↗

Instrumented Bolt Measures Load In Two Ways

Bolt instrumented to allow both ultrasonic and strain-gauge measurements of tensile load in bolt during installation and use of bolt in structure. Bolt head design allows interface for ultrasonic transducer installed, while shallow chamfered circumferential groove on bolt shank contains four strain gauges at equal angular intervals wired as a full-bridge transducer.

Smith, D. E.↗

Application of linear array imaging techniques to the real-time inspection of airframe structures and substructures

Development and application of linear array imaging technologies to address specific aging-aircraft inspection issues is described. Real-time video-taped images were obtained from an unmodified commercial linear-array medical scanner of specimens constructed to simulate typical types of flaws encountered in the inspection of aircraft structures. Results suggest that information regarding the characteristics, location, and interface properties of specific types of flaws in materials and structures may be obtained from the images acquired with a linear array. Furthermore, linear array imaging may offer the advantage of being able to compare 'good' regions with 'flawed' regions simultaneously, and in real time. Real-time imaging permits the inspector to obtain image information from various views and provides the opportunity for observing the effects of introducing specific interventions. Observation of an image in real-time can offer the operator the ability to 'interact' with the inspection process, thus providing new capabilities, and perhaps, new approaches to nondestructive inspections.

Miller, James G.↗

Magnetic Field Experiment Data Analysis System

The Johns Hopkins University Applied Physics Laboratory (JHU/APL) Magnetic Field Experiment Data Analysis System (MFEDAS) has been developed to process and analyze satellite magnetic field experiment data from the TRIAD, MAGSAT, AMPTE/CCE, Viking, Polar BEAR, DMSP, HILAT, UARS, and Freja satellites. The MFEDAS provides extensive data management and analysis capabilities. The system is based on standard data structures and a standard user interface. The MFEDAS has two major elements: (1) a set of satellite unique telemetry processing programs for uniform and rapid conversion of the raw data to a standard format and (2) the program Magplot which has file handling, data analysis, and data display sections. This system is an example of software reuse, allowing new data sets and software extensions to be added in a cost effective and timely manner. Future additions to the system will include the addition of standard format file import routines, modification of the display routines to use a commercial graphics package based on X-Window protocols, and a generic utility for telemetry data access and conversion.

Holland, D. B.↗

Experiment 2: Vapor Transport Crystal Growth of Mercury Cadmium Telluride in Microgravity- USML-2

The new epitaxial growth experiments of Hg(l-x)Cd(x)Te on (100) CdTe substrates by chemical vapor transport (CVT), using HgI2 as a transport agent, were performed in the transient growth regime of this ternary, heteroepitaxial system at normal and reduced gravity during the USML-2 flight. The surface and interface morphology, the compositional and structural uniformity, and carrier mobility of the epitaxial layer and islands grown in microgravity are measurably improved relative to ground specimens. These observations demonstrate the effects of convective flow on the transport, deposition, and growth processes of this solid-vapor system even in the transient growth regime. The properties of the Hg(l-x)Cd(x)Te layer grown in a microgravity environment compare quite favorably to those of layers obtained by other techniques.

Wiedemeier, H.↗