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NASA NTRS1987

Introduction to the computational structural mechanics testbed

The Computational Structural Mechanics (CSM) testbed software system based on the SPAR finite element code and the NICE system is described. This software is denoted NICE/SPAR. NICE was developed at Lockheed Palo Alto Research Laboratory and contains data management utilities, a command language interpreter, and a command language definition for integrating engineering computational modules. SPAR is a system of programs used for finite element structural analysis developed for NASA by Lockheed and Engineering Information Systems, Inc. It includes many complementary structural analysis, thermal analysis, utility functions which communicate through a common database. The work on NICE/SPAR was motivated by requirements for a highly modular and flexible structural analysis system to use as a tool in carrying out research in computational methods and exploring computer hardware. Analysis examples are presented which demonstrate the benefits gained from a combination of the NICE command language with a SPAR computational modules.

Lotts, C. G.↗

NASA NTRS1989

Ground data systems resource allocation process

The Ground Data Systems Resource Allocation Process at the Jet Propulsion Laboratory provides medium- and long-range planning for the use of Deep Space Network and Mission Control and Computing Center resources in support of NASA's deep space missions and Earth-based science. Resources consist of radio antenna complexes and associated data processing and control computer networks. A semi-automated system was developed that allows operations personnel to interactively generate, edit, and revise allocation plans spanning periods of up to ten years (as opposed to only two or three weeks under the manual system) based on the relative merit of mission events. It also enhances scientific data return. A software system known as the Resource Allocation and Planning Helper (RALPH) merges the conventional methods of operations research, rule-based knowledge engineering, and advanced data base structures. RALPH employs a generic, highly modular architecture capable of solving a wide variety of scheduling and resource sequencing problems. The rule-based RALPH system has saved significant labor in resource allocation. Its successful use affirms the importance of establishing and applying event priorities based on scientific merit, and the benefit of continuity in planning provided by knowledge-based engineering. The RALPH system exhibits a strong potential for minimizing development cycles of resource and payload planning systems throughout NASA and the private sector.

Berner, Carol A.↗

NASA NTRS1988

Reduced gravity and ground testing of a two-phase thermal management system for large spacecraft

Experiments were performed aboard the NASA-JSC KC-135 aircraft to study the effect of reduced gravity on two-phase (liquid/vapor) flow and condensation. A prototype two-phase thermal management system for a large spacecraft was tested. Both visual observation and photography of the flow regimes were made. Ground test simulations of the KC-135 flight tests were conducted for comparison purposes. Two-phase pressure drops were predictable by the Heat Transfer Research Institute (HTRI) method, or the Friedel correlation.

Hill, D. G.↗

NASA NTRS1990

Effect of tensile mean stress on fatigue behavior of single-crystal and directionally solidified superalloys

Two nickel base superalloys, single crystal PWA 1480 and directionally solidified MAR-M 246 + Hf, were studied in view of the potential usage of the former and usage of the latter as blade materials for the turbomachinery of the space shuttle main engine. The baseline zero mean stress (ZMS) fatigue life (FL) behavior of these superalloys was established, and then the effect of tensile mean stress (TMS) on their FL behavior was characterized. At room temperature these superalloys have lower ductilities and higher strengths than most polycrystalline engineering alloys. The cycle stress-strain response was thus nominally elastic in most of the fatigue tests. Therefore, a stress range based FL prediction approach was used to characterize both the ZMS and TMS fatigue data. In the past, several researchers have developed methods to account for the detrimental effect of tensile mean stress on the FL for polycrystalline engineering alloys. However, the applicability of these methods to single crystal and directionally solidified superalloys has not been established. In this study, these methods were applied to characterize the TMS fatigue data of single crystal PWA 1480 and directionally solidified MAR-M 246 + Hf and were found to be unsatisfactory. Therefore, a method of accounting for the TMS effect on FL, that is based on a technique proposed by Heidmann and Manson was developed to characterize the TMS fatigue data of these superalloys. Details of this method and its relationship to the conventionally used mean stress methods in FL prediction are discussed.

Kalluri, Sreeramesh↗

NASA NTRS1991

NASA workshop on impact damage to composites

A compilation of slides presented at the NASA Workshop on Impact Damage to Composites held on March 19 and 20, 1991, at the Langley Research Center, Hampton, Virginia is given. The objective of the workshop was to review technology for evaluating impact damage tolerance of composite structures and identify deficiencies. Research, development, design methods, and design criteria were addressed. Actions to eliminate technology deficiencies were developed. A list of those actions and a list of attendees are also included.

Poe, C. C., Jr.↗

NASA NTRS1992

More Genetic Engineering With Cloned Hemoglobin Genes

Cells modified to enhance growth and production of proteins. Method for enhancing both growth of micro-organisms in vitro and production of various proteins or metalbolites in these micro-organisms provides for incorporation of selected chromosomal or extrachormosomal deoxyribonucleic acid (DNA) sequences into micro-organisms from other cells or from artificial sources. Incorporated DNA includes parts encoding desired product(s) or characteristic(s) of cells and parts that control expression of productor characteristic-encoding parts in response to variations in environment. Extended method enables increased research into growth of organisms in oxygen-poor environments. Industrial applications found in enhancement of processing steps requiring oxygen in fermentation, enzymatic degradation, treatment of wastes containing toxic chemicals, brewing, and some oxidative chemical reactions.

Bailey, James E.↗

NASA NTRS1992

Wavelets and electromagnetics

Wavelets are an exciting new topic in applied mathematics and signal processing. This paper will provide a brief review of wavelets which are also known as families of functions with an emphasis on interpretation rather than rigor. We will derive an indirect use of wavelets for the solution of integral equations based techniques adapted from image processing. Examples for resistive strips will be given illustrating the effect of these techniques as well as their promise in reducing dramatically the requirement in order to solve an integral equation for large bodies. We also will present a direct implementation of wavelets to solve an integral equation. Both methods suggest future research topics and may hold promise for a variety of uses in computational electromagnetics.

Kempel, Leo C.↗

NASA NTRS1993

Imaging Genetic Molecules At Atomic Resolution

Proposed method of imaging informational polymeric biological molecules at atomic resolution enables determination of sequences of component monomers about 10 to the 3rd power to 10 to the 4th power times as fast as conventional methods do. Accelerates research on genetic structures of animals and plants. Also contributes significantly to imaging processes like scanning electron microscopy (SEM), atomic-force microscopy (AFM), and scanning tunneling microscopy (STM) in cases in which necessary to locate or identify small specimens on relatively large backgrounds and subtract background images to obtain images of specimens in isolation. V-grooves on silicon wafer laid out in square pattern, intersections of which marked to identify coordinates. Specimen molecules held in grooves for reproducible positioning and scanning by AFM or STM.

Coles, L. Stephen↗

NASA NTRS1990

High temperature superconductor materials and applications

Research on processing methods leading to a significant enhancement in the critical current densities (Jc) and the critical temperature (Tc) of high temperature superconducting in thin bulk and thin film forms. The fabrication of important devices for NASA unique applications (sensors) is investigated.

Doane, George B., III.↗

NASA NTRS1992

The Proteus Navier-Stokes code

An effort is currently underway at NASA Lewis to develop two- and three-dimensional Navier-Stokes codes, called Proteus, for aerospace propulsion applications. The emphasis in the development of Proteus is not algorithm development or research on numerical methods, but rather the development of the code itself. The objective is to develop codes that are user-oriented, easily-modified, and well-documented. Well-proven, state-of-the-art solution algorithms are being used. Code readability, documentation (both internal and external), and validation are being emphasized. This paper is a status report on the Proteus development effort. The analysis and solution procedure are described briefly, and the various features in the code are summarized. The results from some of the validation cases that have been run are presented for both the two- and three-dimensional codes.

Towne, Charles E.↗

NASA NTRS1992

MODIS algorithm development and data visualization using ACTS

The study of the Earth as a system will require the merger of scientific and data resources on a much larger scale than has been done in the past. New methods of scientific research, particularly in the development of geographically dispersed, interdisciplinary teams, are necessary if we are to understand the complexity of the Earth system. Even the planned satellite missions themselves, such as the Earth Observing System, will require much more interaction between researchers and engineers if they are to produce scientifically useful data products. A key component in these activities is the development of flexible, high bandwidth data networks that can be used to move large amounts of data as well as allow researchers to communicate in new ways, such as through video. The capabilities of the Advanced Communications Technology Satellite (ACTS) will allow the development of such networks. The Pathfinder global AVHRR data set and the upcoming SeaWiFS Earthprobe mission would serve as a testbed in which to develop the tools to share data and information among geographically distributed researchers. Our goal is to develop a 'Distributed Research Environment' that can be used as a model for scientific collaboration in the EOS era. The challenge is to unite the advances in telecommunications with the parallel advances in computing and networking.

Abbott, Mark R.↗

NASA NTRS1993

Video luminescent barometry - The induction period

Video monitoring of oxygen quenching of the photoluminescence of platinum octaethylporphyrin (PtOEP) in silicone polymer resin may be used to measure pressure distribution over an airfoil. A continuous increase of the luminescence intensity of PtOEP on exposure to the exciting light is known as the induction effect. The effect of several factors on PtOEP photoluminescence and the induction effect was investigated. The experimental apparatus is described and results are presented. It was observed that the relative induction amplitude and induction time increase at higher oxygen pressure and with thicker films. These observations may be explained if the singlet oxygen produced by oxygen quenching is consumed by the polymer and is therefore unavailable for further quenching. Researchers using this method for measuring pressure distribution on airfoil surfaces should be aware of the induction effect and its implications.

Uibel, Rory H.↗

NASA NTRS1992

Cognitive competencies - Products of genes, experience, and technology

The paper examines methods used in studying cognitive competency in primates. Citing experiments on teaching language skills to chimpanzees, it is shown that some methods used for inquiry might lead to the cultivation and generation of new competencies, and specifically to the development of observational and relational learning skills. It is noted that methods can also limit the generality of conclusions; erroneous conclusions may be made based on certain generally accepted methods, whereby the research might be treatments that profoundly determine the assessment of dependent variables. Particular attention is given to the role of age in learning, showing that young primates can be taught the meaning of lexigrams and many specific tasks in much shorter time than adults; on the basis of these experiments, it was concluded that cultural gains did evolve primarily as a consequence of context within which infants were growing.

Rumbaugh, Duane M.↗

NASA NTRS1992

Learning about primates' learning, language, and cognition

Results are presented of many years of research on the methods of teaching primates the language and cognitive skills which were long considered to be unteachable to particular species of primates. It was found that chimpanzee subjects could not only learn a number of 'stock sentences' but to use them in variations and several combinations for the purpose of solving various problems. Apes placed in different rooms could be taught to communicate via computer, and collaborate with each other on doing specific tasks. Contrary to expectations, young rhesus monkeys proved to be able to learn as much as the chimpanzee species.

Rumbaugh, Duane M.↗

NASA NTRS1992

Effect of tensile mean stress on fatigue behavior of single-crystal and directionally solidified superalloys

Two nickel base superalloys, single crystal PWA 1480 and directionally solidified MAR-M 246 + Hf, were studied in view of the potential usage of the former and usage of the latter as blade materials for the turbomachinery of the Space Shuttle main engine. The baseline zero mean stress (ZMS) fatigue life (FL) behavior of these superalloys was established, and then the effect of tensile mean stress (TMS) on their FL behavior was characterized. A stress range based FL prediction approach was used to characterize both the ZMS and TMS fatigue data. In the past, several researchers have developed methods to account for the detrimental effect of tensile mean stress on the FL for polycrystalline engineering alloys. These methods were applied to characterize the TMS fatigue data of single crystal PWA 1480 and directionally solidified MAR-M 246 + Hf and were found to be unsatisfactory. Therefore, a method of accounting for the TMS effect on FL, that is based on a technique proposed by Heidmann and Manson was developed to characterize the TMS fatigue data of these superalloys. Details of this method and its relationship to the conventionally used mean stress methods in FL prediction are discussed.

Kalluri, Sreeramesh↗

NASA NTRS1990

Animal models in motion sickness research

Practical information on candidate animal models for motion sickness research and on methods used to elicit and detect motion sickness in these models is provided. Four good potential models for use in motion sickness experiments include the dog, cat, squirrel monkey, and rat. It is concluded that the appropriate use of the animal models, combined with exploitation of state-of-the-art biomedical techniques, should generate a great step forward in the understanding of motion sickness mechanisms and in the development of efficient and effective approaches to its prevention and treatment in humans.

Daunton, Nancy G.↗

NASA NTRS1920

Soaring flight in Guinea

The term soaring is applied here to the flight of certain large birds which maneuver in the air without moving their wings. The author explains the methods of his research and here gives approximate figures for the soaring flight of the Egyptian Vulture and the African White backed Vulture. Figures are given in tabular form for relative air speed per foot per second, air velocity per foot per second, lift/drag ratio, and selected coefficients. The author argues that although the figures given were taken from a very limited series of observations, they have nevertheless thrown some light on the use by birds of the internal energy of the air.

Idrac, P↗

NASA NTRS1947

Application of the Analogy Between Water Flow with a Free Surface and Two-dimensional Compressible Gas Flow

The theory of hydraulic analogy, that is, the analogy between water flow with a free surface and two-dimensional compressible gas flow and the limitations and conditions of the analogy are discussed. A test run was made using the hydraulic analogy as applied to the flow about circular cylinders at various diameters at subsonic velocities extending to the super critical range. The apparatus and techniques used in this application are described and criticized. Reasonably satisfactory agreement of pressure distributions and flow fields existed between water and airflow about corresponding bodies. This agreement indicated the possibility of extending experimental compressibility research by new methods.

Orlin, W James↗