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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 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
NASA NTRS2005

Mars Express OMEGA Observations over Terra Meridiani

The OMEGA hyperspectral imager (0.35 to 5.08 micrometers) covered the hematite-bearing plains and underlying etched terrains of Terra Meridiani during several orbits with spatial resolutions ranging from several hundred meters to approximately 2 km. We extracted and analyzed surface reflectance spectra from OMEGA data for the approximately 864,000 square kilometers surrounding the Opportunity site. In this paper we focus on analysis of OMEGA orbit 485 data for the plains and etched terrains located to the northeast of the Opportunity landing site.

Arvidson, R. E.↗
NASA NTRS2005

Mars Express HRSC View of Western Olympus Mons: Evidence for Ice-bearing Deposit and High-Altitude Glaciation

This study is based on the geological analysis of the HRSC images taken on the orbit 0143 (12 m/px in nadir channel). The study area includes the western segment of Olympus Mons and the adjacent lowland plains (Fig. 1). Part of the volcano above the scarp is rather flat and is called "summit plateau" below. What is often called the volcano scarp is a slope classified into three morphologic types: Type 1 (S1 in Fig.1) is the steepest and dominated by ravines in its upper part and by talus beneath; Type 2 (S2) is intermediate in steepness and dominated by downslope trending linear depressions, part of which have channel-like morphology; and Type 3 (S3), is the most gentle and covered by lava flows, continuing from the summit plateau down to the lowland plains.

Basilevsky, A. T.↗
NASA NTRS2005

Polynomial Expressions for Estimating Elastic Constants From the Resonance of Circular Plates

Two approaches were taken to make convenient spread sheet calculations of elastic constants from resonance data and the tables in ASTM C1259 and E1876: polynomials were fit to the tables; and an automated spread sheet interpolation routine was generated. To compare the approaches, the resonant frequencies of circular plates made of glass, hardened maraging steel, alpha silicon carbide, silicon nitride, tungsten carbide, tape cast NiO-YSZ, and zinc selenide were measured. The elastic constants, as calculated via the polynomials and linear interpolation of the tabular data in ASTM C1259 and E1876, were found comparable for engineering purposes, with the differences typically being less than 0.5 percent. Calculation of additional v values at t/R between 0 and 0.2 would allow better curve fits. This is not necessary for common engineering purposes, however, it might benefit the testing of emerging thin structures such as fuel cell electrolytes, gas conversion membranes, and coatings when Poisson s ratio is less than 0.15 and high precision is needed.

Salem, Jonathan A.↗
NASA NTRS1996

Pluto Express: Mission to Pluto

Pluto is the smallest, outermost and last-discovered planet in the Solar System and the only one that has never been visited by a spacecraft from Earth. Pluto and its relatively large satellite Charon are the destinations of a proposed spacecraft mission for the next decade, being developed for NASA by scientists and engineers at NASA's Jet Propulsion Laboratory.

Pluto mission to Pluto Charon Pluto's atmosphere s↗
NASA NTRS1994

Vegetation Species Composition and Canopy Architecture Information Expressed in Leaf Water Absorption Measured in the 1000nm and 2200 nm Spectral Region by an Imaging Spectometer

Plant species composition and plant architectural attributes are critical parameters required for the measuring, monitoring and modeling of terrestrial ecosystems. Remote sensing is commonly cited as an important tool for deriving vegetation properties at an appropriate scale for ecosystem studies, ranging from local, to regional and even synoptic scales (e.g. Wessman 1992).

ecosystem Normalized Difference Vegetation Index (↗
NASA NTRS1997

How to Express C++ Concepts in Fortran90

r summarizes techniques for emulating in Fortran90 the most important object-oriented concepts of C++ classes (including abstract data types, encapsulation and function overloading), inheritance and dynamic dispatching.

Fortran90↗
NASA NTRS2005

DD-PREF: a language for expressing preferences over sets

We present a representation language, DD-PREF (for Diversity and Depth PREFrences), for specifying the desired diversity and depth of sets of objects where each object is represented as a vector of feature values.

user preferences↗
NASA NTRS2007

Cooperative Effects of Corticosteroids and Catecholamines upon Immune Deviation of the Type-1/Type-2 Cytokine Balance in Favor of Type-2 Expression in Human Peripheral Blood Mononuclear Cells

A growing number of studies show strong associations between stress and altered immune function. In vivo studies of chronic and acute stress have demonstrated that cognitive stressors are strongly correlated with high levels of catecholamines (CT) and corticosteroids (CS). Although both CS and CT individually can inhibit the production of T-helper 1 (TH1, type-1 like) cytokines and simultaneously promote the production of T-helper 2 (TH2, type-2 like) cytokines in antigen-specific and mitogen stimulated human leukocyte cultures in vitro, little attention has been focused on the effects of combination CT and CS in immune responses that may be more physiologically relevant. We therefore investigated the combined effects of in vitro CT and CS upon the type-1/type-2 cytokine balance of human peripheral blood mononuclear cells (PBMC) as a model to study the immunomodulatory effects of superimposed acute and chronic stress. Results demonstrated a significant decrease in type-1 cytokine production (IFN-gamma) and a significant increase in type-2 cytokine production (IL-4, IL-10) in our CS+CT incubated cultures when compared to either CT or CS agents alone. Furthermore, variable enhancement of type-1/type-2 immune deviation occurred depending upon when the CT was added. The data suggest that CS can increase the sensitivity of PBMC to the immunomodulatory effects of CT and establishes an in vitro model to study the combined effects of in vivo type-1/type-2 cytokine alterations observed in acute and chronic stress.

Salicru, A. N.↗
NASA NTRS2007

Dramatic Expression in Opera, and Its Implications for Conversational Agents

This article has discussed principles, techniques, and methods of dramatic portrayal in opera, and their application to the development of embodied conversational agents. Investigations such as this complement studies of natural human behavior, and offer insights as to how to make such behavior understandable and interesting when adapted for use by embodied conversational agents. However, one should use caution in applying such lessons. The unique characteristics of computer-based media are still being identified and explored. In any case, one must always be careful about applying principles blindly to any artistic form. Such principles are post-hoc analysis of the intuitive skill of great artists; this was as true in Aristotle's day as it is today. We should not let structural principles stand in the way of injecting creativity into the design of ECAs. Opera at its best possesses an element of magic that is difficult to describe, much less analytically reconstruct. We can only hope to achieve a similar result with conversational agents.

Johnson, W. Lewis↗
NASA NTRS2007

Time-Varying Expression of the Formation Flying along Circular Trajectories

Usually, the formation flying associated with circular orbits is discussed through the well-known Hill s or C-W equations of motion. This paper dares to present and discuss the coordinates that may contain time-varying coefficients. The discussion presents how the controller s performance is affected by the selection of coordinates, and also looks at the special coordinate suitable for designating a target bin to which each spacecraft in the formation has only to be guided. It is revealed that the latter strategy may incorporate the J2 disturbance automatically.

Kawaguchi, Jun'ichiro↗