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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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NASA NTRS1972

COMOC: Thermal analysis variant. User's manual

The Thermal Analysis Variant of the COMOC (computational continuum mechanics) computer system solves problems involving transient heat conduction and convection in stationary continua spanning arbitrarily irregular two-dimensional and axisymmetric solution domains. COMOC is based upon a finite element solution algorithm for the energy equation, and solves for the transient nodal temperature distribution using a highly stable and automatic explicit integration procedure. COMOC is extensively user-oriented, requires minimal input, and no a priori knowledge concerning the stability character of the differential equation system. It can readily output computed data in user-specified format fields, that geometrically resemble the solution domain discretization (for rapid engineering evaluation). Complete information is provided for applying COMOC to a specific problem.

Bauer, A. M.↗
NASA NTRS1972

A superconducting time-variant filtering system.

Description of a laboratory test facility for studying the tracking capabilities of a superconducting time-varying filter system. An RF signal from an antenna is amplified and fed to a mixer; the IF signal modulates an optical diode, and the emitted light is directed through an optical system onto a high-purity high-resistance semiconductor terminating a quarter-wavelength stub in a lead-plated superconducting cavity. The resulting perturbation in the cavity resonant frequency is proportional to the signal modulation present in the light beam. The narrow-band superconducting cavity is thereby acting as a time-variant filter that tracks the instantaneous signal modulation. SNR improvement on the order of 25 dB can be obtained due to the noise rejection characteristics of such a modulation tracking filter.

Arndt, G. D.↗
NASA NTRS1974

COMOC: Three dimensional boundary region variant, programmer's manual

The three-dimensional boundary region variant of the COMOC computer program system solves the partial differential equation system governing certain three-dimensional flows of a viscous, heat conducting, multiple-species, compressible fluid including combustion. The solution is established in physical variables, using a finite element algorithm for the boundary value portion of the problem description in combination with an explicit marching technique for the initial value character. The computational lattice may be arbitrarily nonregular, and boundary condition constraints are readily applied. The theoretical foundation of the algorithm, a detailed description on the construction and operation of the program, and instructions on utilization of the many features of the code are presented.

Orzechowski, J. A.↗
NASA NTRS1987

An enzyme immunoassay for rat growth hormone - Applications to the study of growth hormone variants

A sensitive and specific competitive enzyme immunoassay for rat growth hormone (GH) is described and its use in the detection of GH variants is demonstrated. In the present assay, soluble GH and GH adsorbed to a solid-phase support compete for monkey anti-GH antibody binding sites. The immobilized antibody-GH complex is detected and quantified using goat antimonkey immunoglobin G covalently conjugated to horseradish peroxidase. It is noted that the assay can be performed in 27 hours and that sensitivities in the range of 0.19 to 25 ng can be obtained in the region of 10 to 90 percent binding.

Farrington, Marianne A.↗
NASA NTRS1988

Solutions to time variant problems of real-time expert systems

Real-time expert systems for monitoring and control are driven by input data which changes with time. One of the subtle problems of this field is the propagation of time variant problems from rule to rule. This propagation problem is even complicated under a multiprogramming environment where the expert system may issue test commands to the system to get data and to access time consuming devices to retrieve data for concurrent reasoning. Two approaches are used to handle the flood of input data. Snapshots can be taken to freeze the system from time to time. The expert system treats the system as a stationary one and traces changes by comparing consecutive snapshots. In the other approach, when an input is available, the rules associated with it are evaluated. For both approaches, if the premise condition of a fired rule is changed to being false, the downstream rules should be deactivated. If the status change is due to disappearance of a transient problem, actions taken by the fired downstream rules which are no longer true may need to be undone. If a downstream rule is being evaluated, it should not be fired. Three mechanisms for solving this problem are discussed: tracing, backward checking, and censor setting. In the forward tracing mechanism, when the premise conditions of a fired rule become false, the premise conditions of downstream rules which have been fired or are being evaluated due to the firing of that rule are reevaluated. A tree with its root at the rule being deactivated is traversed. In the backward checking mechanism, when a rule is being fired, the expert system checks back on the premise conditions of the upstream rules that result in evaluation of the rule to see whether it should be fired. The root of the tree being traversed is the rule being fired. In the censor setting mechanism, when a rule is to be evaluated, a censor is constructed based on the premise conditions of the upstream rules and the censor is evaluated just before the rule is fired. Unlike the backward checking mechanism, this one does not search the upstream rules. This paper explores the details of implementation of the three mechanisms.

Yeh, Show-Way↗
NASA NTRS1990

A distinct variant of high-titanium mare basalt from the Van Serg core, Apollo 17 landing site

A fragment of basalt picked from the drive tube collected at Van Serg crater at the Apollo 17 landing site has a bulk chemistry more primitive than that of other high-titanium mare basalt groups collected at the site. The sample has a fine-grained olivine phyric, subophitic texture that is distinct from that of other high-titanium basalt samples. The grain size and texture suggest that the sample has a composition close to that of a magma. The crystallization sequence, with appearance of oxide minerals later than in other groups, and other petrographic features such as more-calcic plagioclase and early pigeonite rather than augite, are consistent with this sample representing a distinct variant of Apollo 17 high-titanium basalts. It is not related through closed-system igneous processes to any of the other mare basalt groups identified among Apollo 17 samples. Its characters emphasize the complexity of contemporaneous magma processes on the moon and the heterogeneity of that part of the mantle that was melted.

Ryder, Graham↗
NASA NTRS1991

A look-ahead variant of the Lanczos algorithm and its application to the quasi-minimal residual method for non-Hermitian linear systems

The Lanczos algorithm can be used both for eigenvalue problems and to solve linear systems. However, when applied to non-Hermitian matrices, the classical Lanczos algorithm is susceptible to breakdowns and potential instabilities. In addition, the biconjugate gradient (BCG) algorithm, which is the natural generalization of the conjugate gradient algorithm to non-Hermitian linear systems, has a second source of breakdowns, independent of the Lanczos breakdowns. Here, we present two new results. We propose an implementation of a look-ahead variant of the Lanczos algorithm which overcomes the breakdowns by skipping over those steps where a breakdown or a near-breakdown would occur. The new algorithm can handle look-ahead steps of any length and requires the same number of matrix-vector products and inner products per step as the classical Lanczos algorithm without look-ahead. Based on the proposed look-ahead Lanczos algorithm, we then present a novel BCG-like approach, the quasi-minimal residual (QMR) method, which avoids the second source of breakdowns in the BCG algorithm. We present details of the new method and discuss some of its properties. In particular, we discuss the relationship between QMR and BCG, showing how one can recover the BCG iterates, when they exist, from the QMR iterates. We also present convergence results for QMR, showing the connection between QMR and the generalized minimal residual (GMRES) algorithm, the optimal method in this class of methods. Finally, we give some numerical examples, both for eigenvalue computations and for non-Hermitian linear systems.

Nachtigal, Noel M.↗
NASA NTRS1991

Variant terminology

A system called Variant Terminology Switching (VTS) is set forth that is intended to provide computer-assisted spellings for terms that have American and British versions. VTS is based on the use of brackets, parentheses, and other symbols in conjunction with letters that distinguish American and British spellings. The symbols are used in the systems as indicators of actions such as deleting, adding, and replacing letters as well as replacing entire words and concepts. The system is shown to be useful for the intended purpose and also for the recognition of misspellings and for the standardization of computerized input/output. The VTS system is of interest to the development of international retrieval systems for aerospace and other technical databases that enhance the use by the global scientific community.

Buchan, Ronald L.↗
NASA NTRS2001

Crystallographic Texture and Orientation Variants in Al2O3-Y3Al5O12 Directionally Solidified Eutectic Crystals

Eutectic rods of Al2O3 and Y3Al5O12 were grown by a laser-heated float zone method, and their microstructure and crystallographic texture were studied by scanning electron microscopy, electron backscattered diffraction and x-ray diffraction. The composites were found to be highly textured with two twin-related crystallographic orientation relationships between the phases. Electron backscattered diffraction was employed to determine the spatial distribution of the orientational variants within the samples and to define the crystallographic orientation of various microstructural features.

Frazer, Colleen S.↗
NASA NTRS1996

Cloning and characterization of the murine homolog of the sno proto-oncogene reveals a novel splice variant

The cellular function(s) of the SNO protein remain undefined. To gain a better understanding of possible developmental roles of this cellular proto-oncogene, we have cloned two murine sno cDNAs and have investigated their expression patterns in embryonic and postnatal tissues. A single major transcript of 7.5 kb is detected in multiple tissues by Northern blot. However, reverse transcriptase polymerase chain reaction (RT-PCR) and RNAse protection assays revealed a novel splice variant in every tissue examined. Two isoforms, termed sno N and sno-dE3 (dE3, deletion within exon 3), were identified. The sno-dE3 isoform employs a novel 5' splice site located within the coding region of the third exon and deletes potential kinase recognition motifs. Transcripts of both sno isoforms accumulate ubiquitously but are most abundant in the developing central nervous system. The in situ hybridization patterns of sno expression during murine development suggest potential roles in tissues with a high degree of cellular proliferation. Expression in terminally differentiated tissues such as muscle and neurons indicates that SNO may have multiple functional activities.

Non-NASA Center↗
NASA NTRS2005

Comparison of Elevated Temperature Tensile Properties and Fatigue Behavior of Two Variants of a Woven SiC/SiC Composite

Tensile properties (elastic modulus, proportional limit strength, in-plane tensile strength, and strain at failure) of two variants of a woven SiC/SiC composite, manufactured during two separate time periods (9/99 and 1/01), were determined at 1038 and 1204 C by conducting tensile tests on specimens machined from plates. Continuous cycling fatigue tests (R = 0.05) and 20 cpm) were also conducted at the same two temperatures on specimens from both composites. In this study, average tensile properties, 95% confidence intervals associated with the tensile properties, and geometric mean fatigue lives of both composite materials are compared. The observed similarities and differences in the tensile properties are highlighted and an attempt is made to understand the relationship, if any, between the tensile properties and the fatigue behaviors of the two woven composites.

Kalluri, Sreeramesh↗
NASA NTRS2020

Development of Concept Illustration Variants of the JUMP Lander

The Artemis program is committed to landing humans on the Moon in the 2020s leading to a sustainable lunar presence by the end of the decade. It is challenging to deliver heavy payloads to the lunar surface in support of these goals given currently available Earth launch systems. The payload capacity of the launch systems limits the size of the lunar landers, thereby limiting their cargo capacity. Fortunately, lander cargo capacity can be significantly increased if multiple landers are joined together in space. This concept has been previously introduced as the Joinable Undercarriage to Maximize Payload (JUMP) Lander. Utilizing a JUMP Lander system will increase options and make it easier to comply with directives issued by senior White House leadership to initiate long duration human activity on the Moon. Such activity, by definition, implies extensive habitation, mobility, research, and resource development capability that in turn calls for significant mass delivery to the lunar surface. This paper develops three concept illustration variants of the JUMP Lander. These concepts explore hypergolic, hydrogen, and methane propellant options, as well as the power and thermal rejection systems necessary to enable such lander concepts. The paper also estimates masses for the necessary avionics, structures, and mechanical subsystems. The paper documents the resulting configurations and recommends a JUMP Lander to carry forward in further development.

Lunar Lander↗
NASA NTRSDate not supplied

Developing a Genetic Variant Calling Pipeline for Quantifying the Complex Mutagenic Load Accumulated in BioNutrients-1 Production Pack Samples

Microorganisms hold great promise for on demand production of labile nutrients and pharmaceuticals as well recycling and in situ resource utilization. The utilization of microorganisms for such tasks on space missions is hindered by the limited data on how microbes respond to spaceflight. For example, the genetic stability of microorganisms, and the genomic engineered traits added to deliver desired functions, over long-term storage in the spacecraft environment is poorly understood. The BioNutrients-1 (BN-1) mission conducted a 5-year study of desiccated storage in Low Earth Orbit (LEO) to evaluate the suitability of eight synthetic biology chassis organisms for long-duration space missions. We are employing high-depth, whole genome sequencing (WGS) to determine the mutagenic load that accumulated during long-term storage. Mutation analysis pipelines are well established for homogenous culture grown from a single colony, but the mutational landscape of the BN-1 samples present a unique analysis challenge, as every cell in the BN-1 samples had a unique genetic journey of DNA damage and repair. Consequently, sequence variants are expected at low allele frequency within samples. To address this genetic complexity, we apply two distinct computational approaches to identify mutations in pre-existing WGS data collected from populations of Chlamydomonas reinhardtii that were exposed to UV mutagenesis and growth in LEO. For reference genome free mutation detection, we utilized DiscoSNP++, which is a de Bruijn graph approach. For reference genome-based mutation detection we utilize GATK for Microbes, which is a Bayesian probabilistic approach. We will benchmark these approaches against the mutations originally identified using CRISP, a method optimized for pooled samples. Ultimately, quantifying the mutation load imposed by storage or growth on the ISS will help identify chassis organisms with both high levels of genome stability and viability, which are desirable traits for implementation of bioproduction in long-duration missions.

SNP↗
NASA NTRS1962

Investigation of the Damping of Liquids in Right-Circular Cylindrical Tanks, Including the Effects of a Time-Variant Liquid Depth

An experimental investigation was conducted to determine the effects of several basic variables upon the damping of the fundamental antisymmetric mode of liquids in right-circular cylindrical tanks without baffles. The variables examined include liquid depth, efflux rate, liquid amplitude, kinematic viscosity, and tank size. The data are presented in dimensionless form and compared with available theory. For the range of variables examined, variations of efflux rate and liquid amplitude were found to have no significant effects on the liquid damping. The following theoretical relationship was found to be adequate for the prediction of the variation of damping with liquid depth, kinematic viscosity, and tank size: [for equation see full text] where v is the kinematic viscosity, R is the cylinder radius, g is the acceleration due to gravity, and h is the liquid depth. However, the constant K was experimentally found in this investigation to have the value 5.23, which is 50 percent higher than the theoretically predicted value.

TANK↗